ORCID Profile
0000-0002-2476-1301
Current Organisation
University of Sydney
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Materials Engineering | Plasmas And Electrical Discharges | Biomaterials | Functional Materials | Biomedical Engineering | Materials Engineering Not Elsewhere Classified | Atomic, Molecular, Nuclear, Particle and Plasma Physics | Condensed Matter Physics—Structural Properties | Colloid And Surface Chemistry | Instruments And Techniques | Polymers and Plastics | Composite and Hybrid Materials | Plasma Physics; Fusion Plasmas; Electrical Discharges | Nanotechnology | Condensed Matter Physics—Electronic And Magnetic Properties; | Medical Devices | Condensed Matter Physics | Glass | Nanotechnology | Elemental Semiconductors | Biosensor Technologies | Metals and Alloy Materials | Nanoscale Characterisation | Other Physical Sciences | Composite Materials | Biomaterials | Environmental Technologies | Physical Chemistry (Incl. Structural) | Electronic and Magnetic Properties of Condensed Matter; Superconductivity | Quantum Physics | Chemical Spectroscopy | Classical Physics | Physical Chemistry Of Macromolecules | Macromolecular and materials chemistry | Complex Physical Systems | Optical Physics Not Elsewhere Classified | Functional materials | Biological Physics | Biophysics | Agricultural Biotechnology | Communications Technologies | Integrated Circuits | Fermentation, Biotechnology And Industrial Microbiology | Optics And Opto-Electronic Physics | Quantum Optics And Lasers | Bioinorganic Chemistry | Solid State Chemistry | Mathematical Physics | Radiation And Matter | Optical And Photonic Systems | Environmental Engineering | Electrical and Electronic Engineering | Nanomaterials | Nanomedicine | Theoretical And Computational Chemistry Not Elsewhere Classified | Interdisciplinary Engineering Not Elsewhere Classified | Sustainable Agricultural Development | Membrane And Separation Technologies | Dental Materials and Equipment | Quantum Optics | Quantum Information, Computation and Communication | Nanoelectronics | Physical Sciences Not Elsewhere Classified | Structural properties of condensed matter | Biological And Medical Chemistry | Microelectronics and Integrated Circuits | Photodetectors, Optical Sensors and Solar Cells | Radiotherapy And Nuclear Medicine | Manufacturing Engineering Not Elsewhere Classified | Polymers | Alloy Materials | Manufacturing Processes and Technologies (excl. Textiles) | Theoretical Physics | Data Security | Condensed Matter Physics—Other | Building Science and Techniques | Theory and design of materials | Cardiology (Incl. Cardiovascular Diseases) | Theoretical and Computational Chemistry | Environmental Technologies | Classical Physics Not Elsewhere Classified | Diagnostic Applications | Pharmacology and Pharmaceutical Sciences not elsewhere classified | Soft Condensed Matter
ANZSRC Socio-Economic Objective (SEO)
Other | Diagnostic methods | Expanding Knowledge in Engineering | Integrated circuits and devices | Polymeric materials (e.g. paints) | Chemical sciences | Manufactured products not elsewhere classified | Expanding Knowledge in the Physical Sciences | Structural Glass and Glass Products | Metals (composites, coatings, bonding, etc.) | Cardiovascular system and diseases | Energy Conservation and Efficiency not elsewhere classified | Materials performance and processes | Diagnostics | Treatments (e.g. chemicals, antibiotics) | Hearing, Vision, Speech and Their Disorders | Medical instrumentation | Expanding Knowledge in Technology | Diagnostic Methods | Machinery and equipment not elsewhere classified | Information processing services | Residential and commercial | Environmentally Sustainable Manufacturing not elsewhere classified | National Security | Other road transport | Appliances and Electrical Machinery and Equipment | Fabricated metal products not elsewhere classified | Ceramics | Structural glass and glass products | Preventive Medicine | Infectious diseases | Cancer and related disorders | Solar-Photovoltaic Energy | Medical Instruments | Public health not elsewhere classified | Telecommunications | Solar-photoelectric | Skeletal System and Disorders (incl. Arthritis) | Industrial machinery and equipment | Other non-ferrous metals (e.g. copper,zinc) | Biological sciences | Rehabilitation of degraded farmland | Physical sciences | Other | Ceramics, glass and industrial mineral products not elsewhere classified | Renewable energy not elsewhere classified (e.g. geothermal) | Construction Materials Performance and Processes not elsewhere classified | Integrated Circuits and Devices | Skeletal system and disorders (incl. arthritis) | Climate Change Mitigation Strategies | Renewable energy | Structural metal products | Other | Health policy evaluation | Machined products | Residential Energy Conservation and Efficiency | Network Infrastructure Equipment | Expanding Knowledge in the Biological Sciences |
Related Links
Publications
Protein immobilization capacity and covalent binding coverage of pulsed plasma polymer surfaces
Publisher: Elsevier BV
Date: 06-2010
Linker-free covalent thermophilic β-glucosidase functionalized polymeric surfaces
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1JM13376D
Titanium nitride/vanadium nitride alloy coatings: Mechanical properties and adhesion characteristics
Publisher: Elsevier BV
Date: 03-2006
Enhancement of absorptance of selective coatings with colloidal films
Publisher: Elsevier BV
Date: 11-1981
Semiconductor properties and redox responses at a-C:N thin film electrochemical electrodes
Publisher: Elsevier BV
Date: 10-2009
Elastic properties of a material composed of alternating layers of negative and positive Poisson's ratio
Publisher: Elsevier BV
Date: 04-2009
Covalent immobilization of enzymes and yeast: Towards a continuous simultaneous saccharification and fermentation process for cellulosic ethanol
Publisher: Elsevier BV
Date: 10-2015
Mechanical Properties of Plasma Immersion Ion Implanted PEEK for Bioactivation of Medical Devices
Publisher: American Chemical Society (ACS)
Date: 07-10-2015
Abstract: Plasma immersion ion implantation (PIII) is used to modify the surface properties of polyether ether ketone for biomedical applications. Modifications to the mechanical and chemical properties are characterized as a function of ion fluence (treatment time) to determine the suitability of the treated surfaces for biological applications. Young's modulus and elastic recovery were found to increase with respect to treatment time at the surface from 4.4 to 5.2 MPa and from 0.49 to 0.68, respectively. The mechanical properties varied continuously with depth, forming a graded layer where the mechanical properties returned to untreated values deep within the layer. The treated surface layer exhibited cracking under cyclical loads, associated with an increased modulus due to dehydrogenation and cross-linking however, it did not show any sign of delamination, indicating that the modified layer is well integrated with the substrate, a critical factor for bioactive surface coatings. The oxygen concentration remained unchanged at the surface however, in contrast to ion implanted polymers containing only carbon and hydrogen, the oxygen concentration within the treated layer was found to decrease. This effect is attributed to UV exposure and suggests that PIII treatments can modify the surface to far greater depths than previously reported. Protein immobilization on PIII treated surfaces was found to be independent of treatment time, indicating that the surface mechanical properties can be tuned for specific applications without affecting the protein coverage. Our findings on the mechanical properties demonstrate such treatments render PEEK well suited for use in orthopedic implantable devices.
A thruster using magnetic reconnection to create a high-speed plasma jet
Publisher: EDP Sciences
Date: 11-2018
Abstract: Plasma thrusters propel spacecraft by the application of Lorentz forces to ionized propellants. Despite evidence that Lorentz forces resulting from magnetic reconnection in solar flares and Earth's magnetopause produce jets of energetic particles, magnetic reconnection has only recently been considered as a means of accelerating plasma in a thruster. Based on theoretical principles, a pulsed magnetic reconnection thruster consisting of two parallel-connected slit coaxial tubes was constructed. The thruster was operated in argon plasma produced by RF energy at 13.56 MHz. A 1.0 ms current pulse of up to 1500 A was applied to the tubes. Three results provide evidence for magnetic reconnection. (1) The production of high-energy electrons resembling the outflow that is observed in the reconnection of field lines in solar flares and in laboratory experiments. (2) The high-energy electron current coincided with the rise of the magnetic field in the thruster and was followed by a large ion current. (3) In accordance with known physics of magnetic reconnection, ion currents were found to increase as the plasma became less collisional. The Alfvén speed of the outflowing ions was calculated to be 8.48 × 10 3 m s − 1 corresponding to an I sp of 860 s.
Plastic scintillation dosimetry: comparison of three solutions for the Cerenkov challenge
Publisher: IOP Publishing
Date: 16-08-2011
DOI: 10.1088/0031-9155/56/18/003
Abstract: In scintillation dosimetry, a Cerenkov background signal is generated when a conventional fibre optic is exposed to radiation produced by a megavoltage linear accelerator. Three methods of measuring dose in the presence of Cerenkov background are compared. In the first method, a second background fibre is used to estimate the Cerenkov signal in the signal fibre. In the second method, a colour camera is used to measure the combined scintillation and Cerenkov light in two wavelength ranges and a mathematical process is used to extract the scintillation signal. In the third method, a hollow air core light guide is used to carry the scintillation signal through the primary radiation field. In this paper, the strengths and weaknesses of each dosimetry system are identified and recommendations for the optimum method for common clinical dosimetry situations are made.
Voltage dependence of cluster size in carbon films using plasma immersion ion implantation
Publisher: Elsevier BV
Date: 05-2003
The radiobiological effect of intra-fraction dose-rate modulation in intensity modulated radiation therapy (IMRT)
Publisher: IOP Publishing
Date: 17-06-2008
DOI: 10.1088/0031-9155/53/13/012
Abstract: Intensity-modulated radiation therapy (IMRT) achieves optimal dose conformity to the tumor through the use of spatially and temporally modulated radiation fields. In particular, average dose rate and instantaneous dose rate (pulse litude) are highly variable within a single IMRT fraction. In this study we isolate these variables and determine their impact on cell survival. Survival was assessed using a clonogenic assay. Two cell lines of differing radiosensitivity were examined: melanoma (MM576) and non-small cell lung cancer (NCI-H460). The survival fraction was observed to be independent of instantaneous dose rate. A statistically significant trend to increased survival was observed as the average dose rate was decreased, for a constant total dose. The results are relevant to IMRT practice, where average treatment times can be significantly extended to allow for movement of the multi-leaf collimator (MLC). Our in vitro study adds to the pool of theoretical evidence for the consequences of protracted treatments. We find that extended delivery times can substantially increase the cell survival. This also suggests that regional variation in the dose-rate history across a tumor, which is inherent to IMRT, will affect radiation dose efficacy.
Free radical functionalization of surfaces to prevent adverse responses to biomedical devices
Publisher: Proceedings of the National Academy of Sciences
Date: 15-08-2011
Abstract: Immobilizing a protein, that is fully compatible with the patient, on the surface of a biomedical device should make it possible to avoid adverse responses such as inflammation, rejection, or excessive fibrosis. A surface that strongly binds and does not denature the compatible protein is required. Hydrophilic surfaces do not induce denaturation of immobilized protein but exhibit a low binding affinity for protein. Here, we describe an energetic ion-assisted plasma process that can make any surface hydrophilic and at the same time enable it to covalently immobilize functional biological molecules. We show that the modification creates free radicals that migrate to the surface from a reservoir beneath. When they reach the surface, the radicals form covalent bonds with biomolecules. The kinetics and number densities of protein molecules in solution and free radicals in the reservoir control the time required to form a full protein monolayer that is covalently bound. The shelf life of the covalent binding capability is governed by the initial density of free radicals and the depth of the reservoir. We show that the high reactivity of the radicals renders the binding universal across all biological macromolecules. Because the free radical reservoir can be created on any solid material, this approach can be used in medical applications ranging from cardiovascular stents to heart-lung machines.
Analytic analysis on asymmetrical micro arcing in high plasma potential RF plasma systems
Publisher: IOP Publishing
Date: 16-01-2006
Optical properties and microstructure of thin silver films
Publisher: Elsevier BV
Date: 08-1991
In situ deposition of high Tc materials using vacuum arc ablation with macroparticle filter
Publisher: Elsevier BV
Date: 10-1925
Cycling effects in nitrogen doped tetrahedral amorphous carbon non-volatile memory cells
Publisher: Elsevier BV
Date: 09-2000
Reply to the comment on: ‘Plastic scintillation dosimetry: comparison of three solutions for the Cerenkov challenge’
Publisher: IOP Publishing
Date: 18-05-2012
Wannier function analysis for understanding disordered structures generated using car-parrinello molecular dynamics
Publisher: Informa UK Limited
Date: 10-2002
Free Radicals Generated by Ion Bombardment of a Semi‐Crystalline PEEK Surface
Publisher: Wiley
Date: 17-10-2011
Apparatus for exposing cell membranes to rapid temperature transients
Publisher: Springer Science and Business Media LLC
Date: 24-09-2003
DOI: 10.1007/S00249-003-0352-5
Abstract: We seek to determine whether cell membranes contain sensors that trigger a downstream response to temperature excursions. To do this, we have developed a novel apparatus for exposing a cell membrane to an extremely rapid temperature excursion in the nanosecond range. Cells are plated on a gold surface that is back-heated by a pulsed laser and cooled by conduction of heat into the glass substrate and the liquid medium. Analysis using the heat diffusion equation shows that the greatest temperature rise is localized within a region tens of nanometres thick, suitable for specifically heating a cell membrane without heating the remainder of a cell. We refer to this device as a nanosecond hotplate.
Smooth thin film C/diamond membranes with controllable optical band gaps
Publisher: Elsevier BV
Date: 04-1992
The origins of self-bias on dielectric substrates in RF plasma processing
Publisher: Elsevier BV
Date: 03-2006
Changes in lung tumor shape during respiration
Publisher: IOP Publishing
Date: 31-01-2012
DOI: 10.1088/0031-9155/57/4/919
Abstract: Evidence that some lung tumors change shape during respiration is derived from respiratory gated CT data by statistical shape modeling and image manipulation. Some tumors behave as rigid objects while others show systematic shape changes. Two views of lung motion are presented to allow analysis of the results. In the first, lung motion is viewed as a wave motion in which inertial effects arising from mass are present and in the second it is a quasistatic motion in which the mass of the lung tissues is neglected. In the first scenario, the extremes of tumor compression and expansion are expected to correlate with maximum upward and downward velocity of the tumor, respectively. In the second, they should occur at end exhale and end inhale, respectively. An observed correlation between tumor strain and tumor velocity provides more support for the first view of lung motion and may explain why previous attempts at observing tumor shape changes during respiration have largely failed. The implications for the optimum gating of radiation therapy are discussed.
Characterisation of titanium nitride thin films prepared using PVD and a plasma immersion ion implantation system
Publisher: Elsevier BV
Date: 05-2002
Free radical kinetics in a plasma immersion ion implanted polystyrene: Theory and experiment
Publisher: Elsevier BV
Date: 06-2012
Growth dynamics of aluminum nitride and aluminum oxide thin films synthesized by ion-assisted deposition
Publisher: AIP Publishing
Date: 02-1988
DOI: 10.1063/1.340068
Abstract: Some aspects of the dynamics of thin-film synthesis of aluminum nitride and aluminum oxide produced by ion-assisted deposition have been deduced from in situ measurements by ellipsometry, photometry, and ion scattering spectroscopy. Measurements obtained during the etching of aluminum films by nitrogen and oxygen ion beams have established the thickness of the synthesized layer and the rate of compound formation. Some of these measurements have been compared with a theoretical model which predicts the time evolution of the synthesized surface layer as well as the steady-state layer thickness. The breakdown voltage and variation of capacitance with applied voltage of aluminum oxide films prepared by ion-assisted deposition are also presented. Furthermore, the optical properties of ion-assisted AlN and Al2O3 in the visible region are given.
Cellular response to modulated radiation fields
Publisher: IOP Publishing
Date: 31-08-2007
DOI: 10.1088/0031-9155/52/18/001
Abstract: Cell survival following exposure to spatially modulated beams, as created by intensity-modulated radiotherapy (IMRT), is investigated. In vitro experiments were performed using malignant melanoma cells (MM576) exposed to a therapeutic megavoltage photon beam. We compared cell survival in modulated fields with cell survival in uniform control fields. Three different spatial modulations of the field were used: a control 'uniform' field in which all cells in a flask were uniformly exposed a 'quarter' field in which 25% of cells at one end of the flask were exposed and a 'striped' field in which 25% of cells were exposed in three parallel stripes. The cell survival in both the shielded and unshielded regions of the modulated fields, as determined by a clonogenic assay, were compared to the cell survival in the uniform field. We have distinguished three ways in which cell survival is influenced by the fate of neighbouring cells. The first of these (type I effect) is the previously reported classical Bystander effect, where cell survival is reduced when communicating with irradiated cells. We find two new types of Bystander effect. The type II effect is an observed increase in cell survival when nearby cells receive a lethal dose. The type III effect is an increase in the survival of cells receiving a high dose of radiation, when nearby cells receive a low dose. These observations of the Bystander effects emphasize the need for improved radiobiological models, which include communicated effects and account for the effects of modulated dose distribution.
MD simulations of Ag film growth using the Lennard-Jones potential
Publisher: IOP Publishing
Date: 04-11-1996
Welding methods for joining thermoplastic polymers for the hermetic enclosure of medical devices
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.MEDENGPHY.2010.04.011
Abstract: New high performance polymers have been developed that challenge traditional encapsulation materials for permanent active medical implants. The gold standard for hermetic encapsulation for implants is a titanium enclosure which is sealed using laser welding. Polymers may be an alternative encapsulation material. Although many polymers are biocompatible, and permeability of polymers may be reduced to acceptable levels, the ability to create a hermetic join with an extended life remains the barrier to widespread acceptance of polymers for this application. This article provides an overview of the current techniques used for direct bonding of polymers, with a focus on thermoplastics. Thermal bonding methods are feasible, but some take too long and/or require two stage processing. Some methods are not suitable because of excessive heat load which may be delivered to sensitive components within the capsule. Laser welding is presented as the method of choice however the establishment of suitable laser process parameters will require significant research.
Properties of hydrogenated carbon films produced by reactive magnetron sputtering
Publisher: Elsevier BV
Date: 11-1981
Bio-Activation of Polyether Ether Ketone Using Plasma Immersion Ion Implantation: A Kinetic Model
Publisher: Wiley
Date: 28-12-2014
Ohmic contact to nitrogen doped amorphous carbon films
Publisher: Elsevier BV
Date: 08-2005
Magnetic and spin properties of tetrahedral amorphous carbon
Publisher: Elsevier BV
Date: 05-1995
Breakdown mechanism of Al2O3 based metal-to-metal antifuses
Publisher: Elsevier BV
Date: 09-2000
Patterns of energy dissipation in three-dimensional face-centred cubic lattices after ion impact
Publisher: IOP Publishing
Date: 09-06-1997
In vivo dosimeters for HDR brachytherapy: A comparison of a diamond detector, MOSFET, TLD, and scintillation detector
Publisher: Wiley
Date: 25-04-2007
DOI: 10.1118/1.2727248
Abstract: The large dose gradients in brachytherapy necessitate a detector with a small active volume for accurate dosimetry. The dosimetric performance of a novel scintillation detector (BrachyFOD) is evaluated and compared to three commercially available detectors, a diamond detector, a MOSFET, and LiF TLDs. An 192Ir HDR brachytherapy source is used to measure the depth dependence, angular dependence, and temperature dependence of the detectors. Of the commercially available detectors, the diamond detector was found to be the most accurate, but has a large physical size. The TLDs cannot provide real time readings and have depth dependent sensitivity. The MOSFET used in this study was accurate to within 5% for distances of 20 to 50 mm from the 192Ir source in water but gave errors of 30%-40% for distances greater than 50 mm from the source. The BrachyFOD was found to be accurate to within 3% for distances of 10 to 100 mm from an HDR 192Ir brachytherapy source in water. It has an angular dependence of less than 2% and the background signal created by Cerenkov radiation and fluorescence of the plastic optical fiber is insignificant compared to the signal generated in the scintillator. Of the four detectors compared in this study the BrachyFOD has the most favorable combination of characteristics for dosimetry in HDR brachytherapy.
Acetylene plasma polymerized surfaces for covalent immobilization of dense bioactive protein monolayers
Publisher: Elsevier BV
Date: 02-2009
Resistive switching and transport characteristics of an all-carbon memristor
Publisher: Elsevier BV
Date: 09-2018
Observation and characterization of memristive silver filaments in amorphous zinc-tin-oxide
Publisher: Springer Science and Business Media LLC
Date: 13-08-2018
DOI: 10.1557/MRC.2018.156
Unifying the optical and electrical properties of amorphous carbon: application to hopping photoconductivity and memristance
Publisher: AIP Publishing
Date: 03-12-2020
DOI: 10.1063/5.0024224
Abstract: Amorphous carbon films with an intermediate content of sp3 atoms are finding applications as resistive switches in devices for bio-sensing and for neuromorphic pattern recognition. To understand resistive switching and photoconductivity in amorphous semiconductors dominated by hopping conduction, we present a theory that unifies the optical and electronic properties. The theory considers all of the states to be localized to various extents instead of being extended electronic states. The electronic density of states (eDOS) is modeled with Gaussian functions, symmetric in energy around the Fermi energy. A “hopping mobility” between localized states that is explicitly both energy and temperature dependent is introduced. We describe an ex le application to amorphous carbon films prepared by using high power impulse magnetron sputtering that have a range of sp3 hybridization fractions of the carbon atoms. The electronic bandgaps of the films are observed to correlate with their optical bandgaps. The eDOS is benchmarked against optical property measurements made by ellipsometry. The theory explains the temperature dependence of the resistivity and predicts that the films should show a temperature dependent hopping photoconductivity. Measurements confirm the presence of the photoconductivity and reveal its spectral dependence. A link is made between persistent hopping photoconductivity and resistive switching.
Plasma immersion ion implantation of poly(tetrafluoroethylene)
Publisher: Elsevier BV
Date: 2004
Carbon diffusion in alumina from carbon and Ti2AlC thin films
Publisher: AIP Publishing
Date: 15-04-2011
DOI: 10.1063/1.3573490
A pulsed cathodic arc spacecraft propulsion system
Publisher: IOP Publishing
Date: 31-07-2009
Plasma‐Treated Polyethylene Surfaces for Improved Binding of Active Protein
Publisher: Wiley
Date: 23-07-2007
Optimizing filter efficiency in pulsed cathodic vacuum arcs operating at high currents
Publisher: IOP Publishing
Date: 31-07-2009
Fuel Selection for Pulsed Cathodic Arc Thrusters
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 2012
DOI: 10.2514/1.B34336
Cell Adhesion to PEEK Treated by Plasma Immersion Ion Implantation and Deposition for Active Medical Implants
Publisher: Wiley
Date: 17-02-2012
Phosphine dissociation on the Si(001) surface
Publisher: American Physical Society (APS)
Date: 23-11-2004
Amorphous diamond-Si semiconductor heterojunctions
Publisher: AIP Publishing
Date: 07-1991
DOI: 10.1063/1.105525
Abstract: Tetrahedrally co-ordinated amorphous carbon (amorphous diamond) deposited from the plasma stream of a vacuum arc on a graphite cathode is demonstrated as having semiconductor properties. The material is shown to form a heterojunction with both p- and n-type Si. A band gap of 2.9 eV is proposed for the a-diamond, based on the observed I-V characteristics of the heterojunction diodes. The material has a measured electrical breakdown strength of 109 V/m, which is comparable to that of high quality insulators such as SiO2 and Si3N4. Gas phase doping using B2H6, PH3, and N2 has been attempted.
Temperature sensitivity and short-term memory in electroforming-free low power carbon memristors
Publisher: AIP Publishing
Date: 22-04-2019
DOI: 10.1063/1.5094652
Abstract: We report temperature dependent electrical characteristics of two-terminal Ag/a-COx/ta-C/Pt memristors. In these asymmetric devices, defects at the Ag/a-COx interface are passivated by oxygen. This alleviates Fermi level pinning and hence increases the height of the Schottky barrier formed at the interface. Electric-field-induced detrapping of electrons from sp2-related defects in the ta-C causes the observed resistive switching. This occurs entirely in the insulating regime, i.e., with conductance ≪ 2e2/h, enabling ultralow power resistive switching (∼6 nW). Nonlinear temperature dependent ON/OFF ratios and short-term memory characteristics (governed by thermal detrapping kinetics) suggest suitability for temporal neuromorphic computing and sensing applications.
Hidden stressors in the clonogenic assay used in radiobiology experiments
Publisher: Springer Science and Business Media LLC
Date: 21-06-2011
DOI: 10.1007/S13246-011-0082-4
Abstract: While clonogenic assays are extensively used in radiobiology, there is no widely accepted procedure for choosing the composition of the cell culture media. Cell line suppliers recommend a specific culture medium for each cell line, however a researcher will frequently customize this aspect of the protocol by supplementing the recommended support medium with additives. For ex le, many researchers add antibiotics, in order to avoid contamination of cells and the consequent loss of data, with little discussion of the influence of the antibiotics on the clonogenic survival of the cells. It is assumed that the effect of any variables in the growth medium on cell survival is taken into consideration by comparing the survival fraction relative to that of controls grown under the same conditions. In the search for better cancer treatment, the effect of various stressors on clonogenic cell survival is under investigation. This study seeks to identify and test potential stressors commonly introduced into the cell culture medium, which may confound the response to radiation.
External magnetic field guiding in HiPIMS to control sp3 fraction of tetrahedral amorphous carbon films
Publisher: IOP Publishing
Date: 04-11-2020
Abstract: Amorphous carbon films have many applications that require control over their sp 3 fraction to customise the electrical, optical and mechanical properties. Ex les of these applications include coatings for machine parts, biomedical and microelectromechanical devices. In this work, we demonstrate the use of a magnetic field with a high-power impulse magnetron sputtering (HiPIMS) source as a simple, new approach to give control over the sp 3 fraction. We provide evidence that this strategy enhances the deposition rate by focusing the flux, giving films with high tetrahedral bonding at the centre of the deposition field and lower sp 3 fractions further from the centre. Resistive switching appears in films with intermediate sp 3 fractions. The production of thin amorphous carbon films with selected properties without the need for electrical bias opens up applications where insulating substrates are required. For ex le, deposition of sp 3 rich films on polymers for wear resistant coatings as well as fabrication of resistive switching devices for neuromorphic technologies that require tuning of the sp 3 fraction on insulating substrates are now possible.
Plasma immersion ion implantation treatment of polyethylene for enhanced binding of active horseradish peroxidase
Publisher: Wiley
Date: 05-09-2007
DOI: 10.1002/JBM.A.31612
Abstract: Robust attachment of active proteins to synthetic surfaces underpins the development of biosensors and protein arrays. This paper presents the results of experiments in which energetic ions, extracted from an inductively coupled nitrogen plasma, are used to modify the surface of ultrahigh molecular weight polyethylene (UHMWPE). The ability of the surface to bind active horseradish peroxidase (HRP) is significantly enhanced by the plasma treatment. The amide signal in infrared spectroscopy indicates an increased quantity of surface-attached protein on the modified surface. The activity of the bound HRP remains high compared with that of protein attached to the untreated surface, after repeated washing in buffer solution. Although Tween 20 was an effective blocking agent for the unmodified polyethylene surface, binding of HRP to the modified surface is not inhibited by its presence. We propose that the treatment produces new binding sites on the surface and that the function of the HRP is retained because the treated surface is substantially more hydrophilic.
Electronic structure models of phosphorusδ
Publisher: American Physical Society (APS)
Date: 29-01-2009
Quantifying plasma immersion ion implantation of insulating surfaces in a dielectric barrier discharge: how to control the dose
Publisher: The Royal Society
Date: 07-2018
Abstract: The plasma physics of dielectric barrier discharges (DBD) for carrying out ion implantation in insulators is investigated. A hollow cathode DBD excited by high-voltage pulses is suitable for ion bombardment of the surfaces of insulating tubing, porous material, particles and sheets. Plasma immersion ion implantation of insulating surfaces is useful for many applications in medicine and engineering. The ion bombardment of glass is useful for cleaning and surface modification. The ion implantation of polymers creates radicals that are able to bind molecules to their surfaces for applications in medical procedures and diagnostics. A wire diagnostic probe and optical emission spectroscopy are used for experimental work. A theory based on mutual capacitance is developed to convert data from the probe to give implanted charge as a function of pressure, voltage and pulse duration. We find the operating conditions that allow for charge to be implanted and those that achieve the highest implanted charge.
Argon plasma immersion ion implantation of polystyrene films
Publisher: Elsevier BV
Date: 04-2008
Antireflection coating of barriers to enhance electron tunnelling: Exploring the matter wave analogy of superluminal optical phase velocity
Publisher: Springer Science and Business Media LLC
Date: 06-10-2017
DOI: 10.1038/S41598-017-13028-5
Abstract: The tunnelling of electrons through barriers is important in field emission sources and in interconnects within electronic devices. Here we use the analogy between the electromagnetic wave equation and the Schrodinger equation to find potential barriers that, when added before an existing barrier, increase the transmission probability. A single pre-barrier of negative potential behaves as a dielectric “antireflection coating”, as previously reported. However, we obtain an unexpected and much greater enhancement of transmission when the pre-barrier has a positive potential of height smaller than the energy of the incident electron, an unfamiliar optical case, corresponding to media with superluminal phase velocities as in dilute free electron media and anomalous dispersion at X-ray frequencies. We use a finite difference time domain algorithm to evaluate the transmission through a triangular field emission barrier with a pre-barrier that meets the new condition. We show that the transmission is enhanced for an incident wavepacket, producing a larger field emission current than for an uncoated barrier. Ex les are given of available materials to enhance transmission in practical applications. The results are significant for showing how to increase electron transmission in field emission and at interconnects between dissimilar materials in all types of electronic devices.
Phosphorus δ-doped silicon: mixed-atom pseudopotentials and dopant disorder effects
Publisher: IOP Publishing
Date: 07-01-2011
DOI: 10.1088/0957-4484/22/6/065701
Abstract: Within a full density functional theory framework we calculate the band structure and doping potential for phosphorus δ-doped silicon. We compare two different representations of the dopant plane pseudo-atoms in which the nuclear charge is fractional between silicon and phosphorus, and explicit arrangements employing distinct silicon and phosphorus atoms. While the pseudo-atom approach offers several computational advantages, the explicit model calculations differ in a number of key points, including the valley splitting, the Fermi level and the width of the doping potential. These findings have implications for parameters used in device modelling.
Soft ferromagnetic materials based on iron/carbon multilayers
Publisher: Elsevier BV
Date: 05-2007
Analysis of carbon content and distribution in a-Si1−xCx:H films by resonant scattering
Publisher: Elsevier BV
Date: 04-1986
Disturbance of a Langmuir Probe at the Steady-State Sheath Boundary in a Drifting Plasma
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2004
Quantifying Moisture Penetration in Encapsulated Devices by Heavy Water Mass Spectrometry: A Standard Moisture Leak Using Poly(ether-ether-ketone)
Publisher: American Chemical Society (ACS)
Date: 10-03-2021
Electric field effects on adsorption/desorption of proteins and colloidal particles on a gold film observed using surface plasmon resonance
Publisher: Elsevier BV
Date: 05-2007
Gas chromatography–mass spectrometry analyses of encapsulated stable perovskite solar cells
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-06-2020
Abstract: Solar cells are subject to heating when operating in sunlight, and the organic components of hybrid perovskite solar cells, especially the commonly used methylammonium cation, can undergo thermal decomposition. Encapsulation can limit decomposition by bringing such reactions to equilibrium and can prevent exposure to damaging ambient moisture. Shi et al. examined several encapsulation schemes for perovskite films and devices by probing volatile products with gas chromatography–mass spectrometry (see the Perspective by Juarez-Perez and Haro). Pressure-tight polymer/glass stack encapsulation was effective in suppressing gas transfer and allowed solar cells containing methylammonium to pass harsh moisture and thermal cycling tests. Science , this issue p. eaba2412 see also p. 1309
Single hydrogen atoms on the Si(001) surface
Publisher: American Physical Society (APS)
Date: 02-10-2007
Physical and psychophysical measures of the distinctiveness of Australian banknotes
Publisher: Informa UK Limited
Date: 2002
Transport properties of arrays of intersecting cylinders
Publisher: Springer Science and Business Media LLC
Date: 05-1981
DOI: 10.1007/BF00935387
Tin oxide artificial synapses for low power temporal information processing
Publisher: IOP Publishing
Date: 08-05-2019
Abstract: Lateral memristors configured with inert Pt contacts and mixed phase tin oxide layers have exhibited immediate, forming-free, low-power bidirectional resistance switching. Activity dependent conductance and relaxation in the low resistance state resembled short term potentiation in biological synapses. After scanning probe microscopy, x-ray photoelectron spectroscopy and electrical measurements, the device characteristics were attributed to Joule heating induced decomposition of the minority SnO phase and formation of a SnO
Effect of Combination l -Citrulline and Metformin Treatment on Motor Function in Patients With Duchenne Muscular Dystrophy
Publisher: American Medical Association (AMA)
Date: 30-10-2019
Erratum: “Time-dependent electrical double layer with blocking electrode” [Appl. Phys. Lett. 94, 043118 (2009)]
Publisher: AIP Publishing
Date: 16-02-2009
DOI: 10.1063/1.3086874
Light-gated amorphous carbon memristors with indium-free transparent electrodes
Publisher: Elsevier BV
Date: 11-2019
Ion implantation in tetrahedral amorphous carbon
Publisher: American Physical Society (APS)
Date: 07-1995
Microstructural investigation supporting an abrupt stress induced transformation in amorphous carbon films
Publisher: AIP Publishing
Date: 15-04-2009
DOI: 10.1063/1.3075867
Abstract: The intrinsic stress of carbon thin films deposited by filtered cathodic arc was investigated as a function of ion energy and Ar background gas pressure. The microstructure of the films was analyzed using transmission electron microscopy, electron energy loss spectroscopy, and Raman spectroscopy. The stress at given substrate bias was reduced by the presence of an Ar background gas and by the presence of a Cu underlayer deposited onto the substrate prior to deposition. Auger electron spectroscopy depth profiles showed no evidence of Ar incorporation into the films. A sharp transition from a sp2 to sp3 rich phase was found to occur at a stress of 6.5±1.5 GPa, independent of the deposition conditions. The structural transition at this value of stress is consistent with available data taken from the literature and also with the expected value of biaxial stress at the phase boundary between graphite and diamond at room temperature. The microstructure of films with stress in the transition region near 6.5 GPa was consistent with a mixture of sp2 and sp3 rich structures.
Trends in optical parameters and band structure with increasing hydrogenation of amorphous silicon
Publisher: Elsevier BV
Date: 10-1983
A fibre optic dosimeter customised for brachytherapy
Publisher: Elsevier BV
Date: 04-2007
Effect of B and the Si/C ratio on high-temperature stability of Si–B–C–N materials
Publisher: IOP Publishing
Date: 11-2006
Breathing as a low frequency wave propagation in nonlinear elastic permeable medium
Publisher: Elsevier BV
Date: 05-2007
PBII deposition of thick carbon coatings from a cathodic arc plasma
Publisher: No publisher found
Date: 2002
Depth-Resolved Structural and Compositional Characterization of Ion-Implanted Polystyrene that Enables Direct Covalent Immobilization of Biomolecules
Publisher: American Chemical Society (ACS)
Date: 15-07-2015
Electron energy-loss study of bonding in amorphous silicon-carbon alloy films prepared with hydrogen dilution
Publisher: AIP Publishing
Date: 05-12-1988
DOI: 10.1063/1.100254
Abstract: Electron energy-loss spectroscopy was used to study the nature of chemical bonding in a-Si1−xCx:H films produced by rf glow discharge decomposition of SiH4/CH4 mixtures with hydrogen dilution. The low-loss region, the Si L edge, and the C K edge were studied. It was found that near stoichiometric films have a high degree of Si to C bonding and that substoichiometric films show some C to C sp2 bonding. A free-electron model was used to interpret the variation of plasmon energy of these films with composition.
Ion-assisted deposition of mixed TiO2-SiO2 films
Publisher: AIP Publishing
Date: 15-08-1989
DOI: 10.1063/1.344352
Abstract: Mixed thin films of TiO2 and SiO2 were produced by coevaporation from separate electron-beam sources and simultaneous bombardment of the growing film with oxygen ions. The optical properties of the films were determined during growth by in situ ellipsometry and the surface composition of the deposited films studied by in situ ion scattering spectroscopy, ex situ x-ray photoelectron spectroscopy, and energy filtered electron diffraction. The correlation between the optical and surface characterization is presented. There is evidence of local variations in the relative concentrations of TiO2 and SiO2. The position of the Si 2p binding energy depends on the TiO2 content in the film, indicating the possible formation of an intimate mixture.
Properties of powders deposited by silane/hydrogen and silane/methane plasmas
Publisher: Elsevier BV
Date: 06-1989
A fibre optic dosimeter for prostate cancer therapy
Publisher: IEEE
Date: 07-2006
Use of in situ ellipsometry to observe phase transitions during boron nitride thin film deposition
Publisher: Elsevier BV
Date: 05-1996
External magnetic field increases both plasma generation and deposition rate in HiPIMS
Publisher: Elsevier BV
Date: 10-2018
Nanoscale Capillary Flows in Alumina: Testing the Limits of Classical Theory
Publisher: American Chemical Society (ACS)
Date: 29-06-2016
DOI: 10.1021/ACS.JPCLETT.6B01021
Abstract: Anodic aluminum oxide (AAO) membranes have well-formed cylindrical channels, as small as 10 nm in diameter, in a close packed hexagonal array. The channels in AAO membranes simulate very small leaks that may be present for ex le in an aluminum oxide device encapsulation. The 10 nm alumina channel is the smallest that has been studied to date for its moisture flow properties and provides a stringent test of classical capillary theory. We measure the rate at which moisture penetrates channels with diameters in the range of 10 to 120 nm with moist air present at 1 atm on one side and dry air at the same total pressure on the other. We extend classical theory for water leak rates at high humidities by allowing for variable meniscus curvature at the entrance and show that the extended theory explains why the flow increases greatly when capillary filling occurs and enables the contact angle to be determined. At low humidities our measurements for air-filled channels agree well with theory for the interdiffusive flow of water vapor in air. The flow rate of water-filled channels is one order of magnitude less than expected from classical capillary filling theory and is coincidentally equal to the helium flow rate, validating the use of helium leak testing for evaluating moisture flows in aluminum oxide leaks.
Molecular dynamics simulations of ion implantation for the fabrication of a solid-state quantum computer
Publisher: Elsevier BV
Date: 2004
Neutron scattering studies of the structure of a highly tetrahedral form of amorphous carbon
Publisher: Elsevier BV
Date: 11-1992
Plasmon dispersion measurements in the electron microscope: Application to carbon solids
Publisher: Elsevier BV
Date: 02-1998
Thickness-dependent stress in sputtered carbon films
Publisher: American Vacuum Society
Date: 05-1994
DOI: 10.1116/1.578814
Abstract: The intrinsic compressive stress in thin carbon films up to 350 nm in thickness, deposited on Si(100) substrates via dc magnetron sputtering, has been measured using ex situ optical interferometry. A plateau value in compressive stress (∼1.5×109 Pa) is observed for carbon films thicker than 85 nm, but an anomalously large stress (up to 50% increase) occurs for film thicknesses between 18 and 85 nm. The carbon film stress data are interpreted in terms of a simple structural model in which the average film density influences the macroscopic stress. Ultrathin carbon films (& nm) in the initial stages of growth were further investigated by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). AFM images of ∼1-nm-thick carbon films and uncoated substrates reveal topographic features with average heights of 4 and 1.5 Å, respectively, but no obvious island film growth structures. XPS measurements, in which the native SiO2 peak is used as a marker of exposed substrate area, suggest that films of ≤2 nm thickness are not continuous. The reported enhanced film stresses are therefore associated with a continuous film structure.
Mechanisms for the behavior of carbon films during annealing
Publisher: American Physical Society (APS)
Date: 08-2004
Plasma-based ion implantation utilising a cathodic arc plasma
Publisher: Elsevier BV
Date: 07-2002
Plasma ion implantation enabled bio-functionalization of PEEK improves osteoblastic activity
Publisher: AIP Publishing
Date: 06-2018
DOI: 10.1063/1.5010346
Abstract: Slow appositional growth of bone in vivo is a major problem associated with polyether ether ketone (PEEK) based orthopaedic implants. Early stage promotion of osteoblast activity, particularly bone nodule formation, would help to improve contact between PEEK implantable materials and the surrounding bone tissue. To improve interactions with bone cells, we explored here the use of plasma immersion ion implantation (PIII) treatment of PEEK to covalently immobilize biomolecules to the surface. In this study, a single step process was used to covalently immobilize tropoelastin on the surface of PIII modified PEEK through reactions with radicals generated by the treatment. Improved bioactivity was observed using the human osteoblast-like cell line, SAOS-2. Cells on surfaces that were PIII-treated or tropoelastin-coated exhibited improved attachment, spreading, proliferation, and bone nodule formation compared to cells on untreated s les. Surfaces that were both PIII-treated and tropoelastin-coated triggered the most favorable osteoblast-like responses. Surface treatment or tropoelastin coating did not alter alkaline phosphatase gene expression and activity of bound cells but did influence the expression of other bone markers including osteocalcin, osteonectin, and collagen I. We conclude that the surface modification of PEEK improves osteoblast interactions, particularly with respect to bone apposition, and enhances the orthopedic utility of PEEK.
Time dependent plasma properties during microarcing in radio frequency plasmas
Publisher: AIP Publishing
Date: 05-11-2007
DOI: 10.1063/1.2806186
Abstract: We report experimental results for time dependent plasma properties during microarcing in a rf plasma system. A cutoff discriminator bias voltage can be defined as a parameter representing plasma potential. The cutoff voltage during the microarcing does not exactly follow the dependence of floating potential. The plasma/ion density increases significantly after microarc initiation and then reduces slowly. We propose that a significant number of electrons enter the plasma in the initial period of the microarc and gain very high energy. These high energy electrons lose their energy through a relatively slower process of collisions while generating a significantly higher plasma density.
A model for stress generation and stress relief mechanisms applied to as-deposited filtered cathodic vacuum arc amorphous carbon films
Publisher: Elsevier BV
Date: 06-2005
Effects of layer patterns on magnetic and other properties of single and multilayered Fe–C films
Publisher: AIP Publishing
Date: 02-2007
DOI: 10.1063/1.2432882
Abstract: The structure and magnetic properties of Fe–C films synthesized using dual cathodes and coaxial cathodes in a filtered high current pulsed cathodic vacuum arc were studied. By altering the experimental parameters such as the trigger sequence, period, and pulse length, a series of single and multilayered Fe–C films were deposited. X-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy were utilized to study the composition and microstructure of the films. The magnetic properties were studied using a superconducting quantum interference device magnetometer. The hysteresis loops show that the magnetic properties are controlled by the pattern of the layers and Fe concentration in the films. The reduction in the coercive field when Fe layers are mixed with ta-C layers is a key result and confirms that magnetically soft materials can be created by the multilayer method. The relationship between the magnetic properties and the structure of single and multilayered Fe–C films is discussed.
Graphitization of Glassy Carbon after Compression at Room Temperature
Publisher: American Physical Society (APS)
Date: 23-05-2018
Correlation between stress and hardness in pulsed cathodic arc deposited titanium/vanadium nitride alloys
Publisher: IOP Publishing
Date: 30-10-2004
Enhanced Water Vapor Flow in Silica Microchannels: The Effect of Adsorbed Water on Tangential Momentum Accommodation
Publisher: American Chemical Society (ACS)
Date: 15-09-2015
Ion-implanted polytetrafluoroethylene enhances Saccharomyces cerevisiae biofilm formation for improved immobilization
Publisher: The Royal Society
Date: 13-06-2012
Abstract: The surface of polytetrafluoroethylene (PTFE) was modified using plasma immersion ion implantation (PIII) with the aim of improving its ability to immobilize yeast. The density of immobilized cells on PIII-treated and -untreated PTFE was compared as a function of incubation time over 24 h. Rehydrated yeast cells attached to the PIII-treated PTFE surface more rapidly, with higher density, and greater attachment strength than on the untreated surface. The immobilized yeast cells were removed mechanically or chemically with sodium hydroxide and the residues left on the surfaces were analysed with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). The results revealed that the mechanism of cell attachment on both surfaces differs and a model is presented for each. Rapid attachment on the PIII-treated surface occurs through covalent bonds of cell wall proteins and the radicals on the treated surface. In contrast, on the untreated surface, only physisorbed molecules were found in the residue and lipids were more highly concentrated than proteins. The presence of lipids in the residue was found to be a consequence of damage to the plasma membrane during the rehydration process and the increased cell stress was also apparent by the amount of Hsp12 in the protein residue. The immobilized yeast cells on PIII-treated PTFE were found to be as active as yeast cells in suspension.
Numerical simulation of metal plasma-immersion ion implantation and deposition on a cone
Publisher: AIP Publishing
Date: 22-11-2004
DOI: 10.1063/1.1808919
Abstract: A two-dimensional particle-in-cell simulation in r-z cylindrical co-ordinates is used to model metal plasma-immersion ion implantation and deposition on a cone. We show that a sharp cone mounted on a plane or stage exhibits an ion-focusing effect, such that an increased ion dose at the sides of conical features will occur during the application of high negative voltage plasma-immersion ion implantation pulses. This focusing effect is due to the shape of the equilibrium sheath and is strongly enhanced by sharper cones. The focusing effect increases for sharper cones and the ion trajectories bend more sharply. However, this deflection of the trajectories is not strong enough to direct the ions normal to the cone surface. Consequently, sharper cones exhibit a more oblique incident angle for the implanted ions.
A combinatorial comparison of DC and high power impulse magnetron sputtered Cr2AlC
Publisher: Elsevier BV
Date: 11-2014
Raman spectra of partially oriented sp2 carbon films: Experimental and modelled
Publisher: Elsevier BV
Date: 08-2006
Cathodic arc co-deposition of highly oriented hexagonal Ti and Ti2AlC MAX phase thin films
Publisher: Elsevier BV
Date: 11-2010
Production of dense and oriented structures including titanium nitride by energetic condensation from plasmas
Publisher: Elsevier BV
Date: 06-1996
Orientation and conformation of anti-CD34 antibody immobilised on untreated and plasma treated polycarbonate
Publisher: Elsevier BV
Date: 04-0006
DOI: 10.1016/J.ACTBIO.2015.02.027
Abstract: The conformation and orientation of proteins immobilised on synthetic materials determine their ability to bind their antigens and thereby the sensitivity of the microarrays and biosensors employing them. Plasma immersion ion implantation (PIII) of polymers significantly increases both their wettability and protein binding capacity. This paper addresses the hypothesis that a PIII treated polymer surface modifies the native protein conformation less significantly than a more hydrophobic untreated surface and that the differences in surface properties also affect the protein orientation. To prove this, the orientation and conformation of rat anti-mouse CD34 antibody immobilized on untreated and PIII treated polycarbonate (PC) were investigated using ToF-SIMS and FTIR-ATR spectroscopy. Analysis of the primary structure of anti-CD34 antibody and principal component analysis of ToF-SIMS data were applied to detect the difference in the orientation of the antibody attached to untreated and PIII treated PC. The difference in the antibody conformation was analysed using deconvolution of the Amide I peak (in FTIR-ATR spectra) and curve-fitting. It was found that compared to the PIII treated s le, the antibody immobilized on the untreated PC s le has a secondary structure with a lower fraction of β-sheets and a higher fraction of α-helices and disordered fragments. Also, it was found that anti-CD34 antibody has a higher tendency to occur in the inactive 'tail-up' orientation when immobilized on an untreated PC surface than on a PIII treated surface. These findings confirm the above hypothesis.
A novel method for thickness profile control in RF PECVD deposition on large area substrates
Publisher: Elsevier BV
Date: 04-2006
Non-Thermal effects in the microwave induced unfolding of proteins observed by chaperone binding
Publisher: Wiley
Date: 2008
DOI: 10.1002/BEM.20382
Abstract: We study the effect of microwaves at 2,450 MHz on protein unfolding using surface plasmon resonance sensing. Our experimental method makes use of the fact that unfolding proteins tend to bind to chaperones on their unfolding pathway and this attachment is readily monitored by surface plasmon resonance. We use the protein citrate synthase (CS) for this study as it shows strong binding to the chaperone alpha crystallin when stressed by exposure to excess temperature. The results of microwave heating are compared with the effect of ambient heating and a combination of ambient and microwave heating to the same final temperature. We study the temperature distributions during the heating process. We show that microwaves cause a significantly higher degree of unfolding than conventional thermal stress for protein solutions heated to the same maximum temperature.
Science of Water Leaks: Validated Theory for Moisture Flow in Microchannels and Nanochannels
Publisher: American Chemical Society (ACS)
Date: 15-10-2015
DOI: 10.1021/ACS.LANGMUIR.5B02183
Abstract: Water is ubiquitous the science of its transport in micro- and nanochannels has applications in electronics, medicine, filtration, packaging, and earth and planetary science. Validated theory for water vapor and two-phase water flows is a "missing link" completing it enables us to define and quantify flow in a set of four standard leak configurations with dimensions from the nanoscale to the microscale. Here we report the first measurements of water vapor flow rates through four silica microchannels as a function of humidity, including under conditions when air is present as a background gas. An important finding is that the tangential momentum accommodation coefficient (TMAC) is strongly modified by surface layers of adsorbed water molecules, in agreement with previous work on the TMAC for nitrogen molecules impacting a silica surface in the presence of moisture. We measure enhanced flow rates for two-phase flows in silica microchannels driven by capillary filling. For the measurement of flows in nanochannels we use heavy water mass spectrometry. We construct the theory for the flow rates of the dominant modes of water transport through each of the four standard configurations and benchmark it against our new measurements in silica and against previously reported measurements for nanochannels in carbon nanotubes, carbon nanopipes, and porous alumina. The findings show that all behavior can be described by the four standard leak configurations and that measurements of leak behavior made using other molecules, such as helium, are not reliable. Single-phase water vapor flow is overestimated by a helium measurement, while two-phase flows are greatly underestimated for channels larger than 100 nm or for all channels when boundary slip applies, to an extent that depends on the slip length for the liquid-phase flows.
Atomistic simulation of energy and temperature effects in the deposition and implantation of amorphous carbon thin films
Publisher: Elsevier BV
Date: 10-2003
P2 dimer implantation in silicon: A molecular dynamics study
Publisher: Elsevier BV
Date: 10-2006
Reply to 'Comments on cellular response to modulated radiation fields'
Publisher: IOP Publishing
Date: 10-02-2009
Pulsed external magnetic fields increase the deposition rate in reactive HiPIMS while preserving stoichiometry: An application to amorphous HfO2
Publisher: AIP Publishing
Date: 08-09-2016
DOI: 10.1063/1.4961730
Abstract: We compare the use of externally applied pulsed and steady magnetic fields for the enhancement of deposition rate in reactive High Power Impulse Magnetron Sputtering (HiPIMS), using the deposition of amorphous hafnium oxide (a-HfO2) on Si as an ex le. The external magnetic fields were applied by a solenoidal coil, placed above the magnetron target. In the case of a steady magnetic field, a higher voltage was required to initiate the HiPIMS discharge, a longer delay time was observed for current onset, and the films became substoichiometric. For the pulsed magnetic field, film stoichiometry was maintained under all applied external magnetic field strengths. Varying the duration and delay times of the magnetic field after the application of HiPIMS voltage pulse revealed that the afterglow of the plasma between HiPIMS pulses was actively quenched by the presence of the magnetic field. Therefore, the optimum operation with the highest plasma density was obtained by applying the external magnetic field only when the plasma was established and removing it at the end of the HiPIMS pulse. A model to explain the findings is presented in which the target poisoning by oxide formation is determined by the conditions in the afterglow. We describe an approach to achieve maximum deposition rate while maintaining film stoichiometry and high film quality. Amorphous HfO2 films with leakage current through the film of less than 5 × 10−5 A/cm2 at 0.1 MV/cm were obtained at the maximum deposition rate. The refractive index, at a wavelength of 500 nm, of the film prepared with pulsed magnetic field was 2.05 with a very low extinction coefficient of 8 × 10−5.
Electron-diffraction study of chemical ordering in glow-dischargea-
Publisher:
American Physical Society (APS)
Date:
15-05-1988
Publisher: American Physical Society (APS)
Date: 15-05-1988
A high-current pulsed cathodic vacuum arc plasma source
Publisher: AIP Publishing
Date: 28-10-2003
DOI: 10.1063/1.1614851
Abstract: Cathodic vacuum arcs (CVAs) are well established as a method for producing metal plasmas for thin film deposition and as a source of metal ions. Fundamental differences exist between direct current (dc) and pulsed CVAs. We present here results of our investigations into the design and construction of a high-current center-triggered pulsed CVA. Power supply design based on electrolytic capacitors is discussed and optimized based on obtaining the most effective utilization of the cathode material. Anode configuration is also discussed with respect to the optimization of the electron collection capability. Type I and II cathode spots are observed and discussed with respect to cathode surface contamination. An unfiltered deposition rate of 1.7 nm per pulse, at a distance of 100 mm from the source, has been demonstrated. Instantaneous plasma densities in excess of 1×1019 m−3 are observed after magnetic filtering. Time averaged densities an order of magnitude greater than common dc arc densities have been demonstrated, limited by pulse repetition rate and filter efficiency.
New developments in processing cathodic arc plasmas
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 1997
DOI: 10.1109/27.640680
Water on silicon (001): C defects and initial steps of surface oxidation
Publisher: American Physical Society (APS)
Date: 22-05-2008
A novel pin-on-apparatus
Publisher: Elsevier BV
Date: 2003
Relation of optical and electrical properties to the microstructure of intrinsic transparent conducting ZnO thin films
Publisher: SPIE
Date: 20-05-2009
DOI: 10.1117/12.821629
Oxygen incorporation in Ti2AlC: Tuning of anisotropic conductivity
Publisher: AIP Publishing
Date: 16-08-2010
DOI: 10.1063/1.3472280
Abstract: The substitution of oxygen for carbon in Ti2AlC M(n+1)AXn (MAX) phase, forming Ti2AlC1−xOx, has recently been reported. In this paper we simulate the effect of oxygen incorporation on mechanical and electronic properties using ab initio calculations. While the mechanical properties are not sensitive to the change in composition, the electronic properties can be tuned by varying the oxygen concentration. As the concentration increases, the conduction changes from in plane, typical of MAX phases, to conduction also in the c-direction. The conduction along c passes from insulating to n-type and then finally to p-type. These findings reveal an anisotropic semiconducting material.
Plasma Activation and Self Bonding of PEEK for the Use in the Encapsulation of Medical Implants
Publisher: Wiley
Date: 20-09-2010
Abstract: Polyether ether ketone (PEEK) and its composites have emerged as one of the main candidate materials for replacing titanium and its alloys for the encapsulating components of medical implants. PEEK, however, is a difficult material to bond without the use of adhesion promoting agents. Experiments based on the central composite rotatable design (CCRD) were used to find an optimum plasma surface modification treatment. X‐ray photoelectron spectrometry (XPS), contact angle measurements and scanning electron microscopy (SEM) were used to provide surface molecular and thermodynamic information. Higher self bond strength of PEEK was found to correlate with higher relative oxygen concentration and total surface energy. Mechanisms for the autohesive bond formation were developed based on the oxidation of the surface. magnified image
Plasma transport and optical flares in high-density plasmas produced from a pulsed cathodic arc
Publisher: Elsevier BV
Date: 08-2004
Plasma immersion ion implantation using polymeric substrates with a sacrificial conductive surface layer
Publisher: Elsevier BV
Date: 07-2002
An integrated solution for rapid biosensing with robust linker free covalent bindingsurfaces
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.BIOS.2012.11.015
Abstract: A novel integrated biosensor methodology is proposed and demonstrated. The methodology utilizes a nitrogen-containing plasma polymer to achieve linker-free binding of a layer of biorecognition molecules. The sensor surface has been shown to maintain its performance after freeze-drying providing a long shelf life under ambient conditions. The sensor is configured for single wavelength ellipsometric detection providing a low cost, versatile, and rapid sensing and diagnosis platform suitable for a wide range of applications and end-users. The merits of the methodology are demonstrated using three antigen-antibody pairs.
Influence of gas flow rate and entry point on ion charge, ion counts and ion energy distribution in a filtered cathodic arc
Publisher: Elsevier BV
Date: 07-2002
Applications of tetrahedral amorphous carbon in limited volatility memory and in field programmable gate arrays
Publisher: Elsevier BV
Date: 02-2001
Optical and electronic properties of amorphous diamond
Publisher: Elsevier BV
Date: 04-1993
High pressure phases produced by low energy ion implantation with reference to cubic boron nitride
Publisher: Elsevier BV
Date: 12-1995
An omics approach to delineating the molecular mechanisms that underlie the biological effects of physical plasma
Publisher: AIP Publishing
Date: 03-2023
DOI: 10.1063/5.0089831
Abstract: The use of physical plasma to treat cancer is an emerging field, and interest in its applications in oncology is increasing rapidly. Physical plasma can be used directly by aiming the plasma jet onto cells or tissue, or indirectly, where a plasma-treated solution is applied. A key scientific question is the mechanism by which physical plasma achieves selective killing of cancer over normal cells. Many studies have focused on specific pathways and mechanisms, such as apoptosis and oxidative stress, and the role of redox biology. However, over the past two decades, there has been a rise in omics, the systematic analysis of entire collections of molecules in a biological entity, enabling the discovery of the so-called “unknown unknowns.” For ex le, transcriptomics, epigenomics, proteomics, and metabolomics have helped to uncover molecular mechanisms behind the action of physical plasma, revealing critical pathways beyond those traditionally associated with cancer treatments. This review showcases a selection of omics and then summarizes the insights gained from these studies toward understanding the biological pathways and molecular mechanisms implicated in physical plasma treatment. Omics studies have revealed how reactive species generated by plasma treatment preferentially affect several critical cellular pathways in cancer cells, resulting in epigenetic, transcriptional, and post-translational changes that promote cell death. Finally, this review considers the outlook for omics in uncovering both synergies and antagonisms with other common cancer therapies, as well as in overcoming challenges in the clinical translation of physical plasma.
Plasma Polymer Surfaces Compatible with a CMOS Process for Direct Covalent Enzyme Immobilization
Publisher: Wiley
Date: 10-01-2009
Evaluation of corrosion resistance and cytocompatibility of graded metal carbon film on Ti and NiTi prepared by hybrid cathodic arc/glow discharge plasma-assisted chemical vapor deposition
Publisher: Elsevier BV
Date: 08-2015
Native oxides and their effect on electrochemical characteristics of ta-C:N films
Publisher: Elsevier BV
Date: 08-2013
Linker-protein G mediated functionalization of polystyrene-encapsulated upconversion nanoparticles for rapid gene assay using convective PCR.
Publisher: Springer Science and Business Media LLC
Date: 11-05-2019
DOI: 10.1007/S00604-019-3466-X
Abstract: The authors report on a simplified approach to encapsulate upconversion nanoparticles (UCNPs) in polystyrene spheres by mini-emulsion polymerisation. The resulting particles (PS-UCNP) are hydrophilic, stable and suitable for biomolecular recognition and biosensing applications. Also, a strategy was developed for bioconjugation of antibodies onto the surface of the PS-UCNPs by using the bifunctional fusion protein linker-protein G (LPG). LPG mediates the functionalisation of PS-UCNPs with antibodies against digoxigenin allowing for specific labelling of convective PCR (cPCR) licons. Lambda DNA was lified using cPCR on a heat block for 30 min using the digoxigenin labelled forward and biotin labelled reverse primers. The antibody functionalised PS-UCNPs bind to the digoxigenin end of the cPCR licons. Finally, the streptavidin labelled magnetic beads were used to selectively capture the PS-UCNP-labelled cPCR licons and the upconversion signal was detected at 537 nm under 980 nm excitation. This sandwich approach enables direct recognition of the target lambda DNA with a detection limit of 10
Time-dependent electrical double layer with blocking electrode
Publisher: AIP Publishing
Date: 26-01-2009
DOI: 10.1063/1.3077605
Abstract: This paper deals with the experimental observation of time-dependent electrical double layer (EDL) in electrolyte. A potential-distance diagram is used to fully understand different stages in the formation of EDL. The influence of the thickness of the blocking layer and the ionic strength to the formation of EDL is discussed based on the equivalent circuit. With this simple method, it is found that in addition to Debye screening length, the frequency has to be considered if an alternating electric field is used to control the movement of charged biomolecules inside EDL.
The mechanism of light reflectance in silverfish
Publisher: The Royal Society
Date: 08-03-2001
Cathodic arc ablation as a new method of high-Tc superconductor deposition
Publisher: Elsevier BV
Date: 07-1992
Effects of pulse voltage and deposition time on the adhesion strength of graded metal/carbon films deposited on bendable stainless steel foils by hybrid cathodic arc – glow discharge plasma assisted c
Publisher: Elsevier BV
Date: 03-2016
Cell surface antigen profiling using a novel type of antibody array immobilised to plasma ion-implanted polycarbonate
Publisher: Springer Science and Business Media LLC
Date: 13-03-2014
DOI: 10.1007/S00018-014-1595-2
Abstract: To identify and sort out subpopulations of cells from more complex and heterogeneous assemblies of cells is important for many biomedical applications, and the development of cost- and labour-efficient techniques to accomplish this is warranted. In this report, we have developed a novel array-based platform to discriminate cellular populations based on differences in cell surface antigen expressions. These cell capture microarrays were produced through covalent immobilisation of CD antibodies to plasma ion immersion implantation-treated polycarbonate (PIII-PC), which offers the advantage of a transparent matrix, allowing direct light microscopy visualisation of captured cells. The functionality of the PIII-PC array was validated using several cell types, resulting in unique surface antigen expression profiles. PIII-PC results were compatible with flow cytometry, nitrocellulose cell capture arrays and immunofluorescent staining, indicating that the technique is robust. We report on the use of this PIII-PC cluster of differentiation (CD) antibody array to gain new insights into neural differentiation of mouse embryonic stem (ES) cells and into the consequences of genetic targeting of the Notch signalling pathway, a key signalling mechanism for most cellular differentiation processes. Specifically, we identify CD98 as a novel marker for neural precursors and polarised expression of CD9 in the apical domain of ES cell-derived neural rosettes. We further identify expression of CD9 in hitherto uncharacterised non-neural cells and enrichment of CD49e- and CD117-positive cells in Notch signalling-deficient ES cell differentiations. In conclusion, this work demonstrates that covalent immobilisation of antibody arrays to the PIII-PC surface provides faithful cell surface antigen data in a cost- and labour-efficient manner. This may be used to facilitate high throughput identification and standardisation of more precise marker profiles during stem cell differentiation and in various genetic and disease contexts.
Investigation of cytocompatibility of surface-treated cellulose nitrate films by using plasma immersion ion implantation
Publisher: Elsevier BV
Date: 04-2007
Fundamentals of siRNA and miRNA therapeutics and a review of targeted nanoparticle delivery systems in breast cancer
Publisher: Springer Science and Business Media LLC
Date: 11-01-2018
Phosphine dissociation and diffusion on Si(001) observed at the atomic scale
Publisher: American Chemical Society (ACS)
Date: 02-2006
DOI: 10.1021/JP054646V
Abstract: A detailed atomic-resolution scanning tunneling microscopy (STM) and density functional theory study of the adsorption, dissociation, and surface diffusion of phosphine (PH(3)) on Si(001) is presented. Adsorbate coverages from approximately 0.01 monolayer to saturation are investigated, and adsorption is performed at room temperature and 120 K. It is shown that PH(3) dissociates upon adsorption to Si(001) at room temperature to produce both PH(2) + H and PH + 2H. These appear in atomic-resolution STM images as features asymmetric-about and centered-upon the dimer rows, respectively. The ratio of PH(2) to PH is a function of both dose rate and temperature, and the dissociation of PH(2) to PH occurs on a time scale of minutes at room temperature. Time-resolved in situ STM observations of these adsorbates show the surface diffusion of PH(2) adsorbates (mediated by its lone pair electrons) and the dissociation of PH(2) to PH. The surface diffusion of PH(2) results in the formation of hemihydride dimers on low-dosed Si(001) surfaces and the ordering of PH molecules along dimer rows at saturation coverages. The observations presented here have important implications for the fabrication of atomic-scale P dopant structures in Si, and the methodology is applicable to other emerging areas of nanotechnology, such as molecular electronics, where unambiguous molecular identification using STM is necessary.
Accurate determination of optical and electronic properties of ultra-thin silver films for biosensor applications
Publisher: Elsevier BV
Date: 08-2005
An efficientab initiocalculation of powder diffraction intensity using Debye's equation
Publisher: International Union of Crystallography (IUCr)
Date: 26-10-2001
DOI: 10.1107/S0108767301012624
Abstract: The Debye equation gives the spherically averaged diffracted intensity from a group of atoms and is exact under the first Born, or kinematic, approximation. Algebraic simplifications are developed for calculating multiplicities in the double summation and are used in a new algorithm for implementing this equation. The results for cubic, body-centred cubic and face-centred cubic systems agree exactly with previous methods while achieving substantial computational advantage.
Percolation threshold in ultrathin titanium films determined byin situspectroscopic ellipsometry
Publisher: American Physical Society (APS)
Date: 08-11-2004
Defect-induced dimer pinning on the Si(001) surface
Publisher: Elsevier BV
Date: 08-2005
Microarcing instability in RF PECVD plasma system
Publisher: Elsevier BV
Date: 08-2005
Synthesis and in-situ ellipsometric monitoring of Ti/C nanostructured multilayers using a high-current, dual source pulsed cathodic arc
Publisher: Elsevier BV
Date: 06-2005
Flat-topped broadband rugate filters
Publisher: Optica Publishing Group
Date: 20-10-2006
DOI: 10.1364/AO.45.007841
Abstract: A method of creating rugate interference filters that have flat-topped reflectance across an extended spectral region is presented. The method applies known relations from the classical coupled wave theory to develop a set of equations that gives the spatial frequency distribution of rugate cycles to achieve constant reflectance across a given spectral region. Two ex les of the application of this method are discussed: a highly reflective coating for eye protection against harmful laser radiation incident from normal to 45 degrees , and a spectral beam splitter for efficient solar power conversion.
Etching and structural changes of polystyrene films during plasma immersion ion implantation from argon plasma
Publisher: Elsevier BV
Date: 10-2006
Design of shallow acceptors in ZnO through early transition metals codoped with N acceptors
Publisher: American Physical Society (APS)
Date: 10-02-2011
In situ analysis of the structural transformation of glassy carbon under compression at room temperature
Publisher: American Physical Society (APS)
Date: 30-01-2019
Comparison on protein adsorption properties of diamond-like carbon and nitrogen-containing plasma polymer surfaces
Publisher: Elsevier BV
Date: 2012
Dark field microscopy for diffraction analysis of non crystalline materials
Publisher: Oxford University Press (OUP)
Date: 08-2004
DOI: 10.1017/S1431927604886379
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.
Optical resonances of three-phase composites and anomalies in transmission
Publisher: Elsevier BV
Date: 05-1995
Relation between microstructure and stress in titanium nitride films grown by plasma immersion ion implantation
Publisher: AIP Publishing
Date: 21-03-2003
DOI: 10.1063/1.1558995
Abstract: Polycrystalline and microcrystalline materials grown as thin films often exhibit a preferred crystallographic orientation. The mechanism by which this preferred orientation develops has been the subject of some debate. In this article we present the results of electron microscopy and diffraction experiments examining preferred orientation in titanium–nitride (TiN) films deposited by physical vapor deposition with bombardment energies up to 18 keV using plasma immersion ion implantation. We show that as the bombardment energy increases the intrinsic stress is reduced. For ex le, at 3 kV more than a 50% reduction in stress is achieved. The results are consistent with a model in which the preferred orientation is the result of minimizing the energy, which includes both surface energy and bulk strain energy terms.
Correlation of film structure and molecular oxygen reduction at nitrogen doped amorphous carbon thin film electrochemical electrodes
Publisher: Elsevier BV
Date: 09-2009
Neutron-scattering studies of the structure of highly tetrahedral amorphous diamondlike carbon
Publisher: American Physical Society (APS)
Date: 02-09-1991
Production of highly ionized species in high-current pulsed cathodic arcs
Publisher: AIP Publishing
Date: 31-05-2010
DOI: 10.1063/1.3442509
Abstract: Time resolved optical diagnostic techniques were used to study the production of highly ionized species in aluminum plasma produced by a centered-triggered high-current pulsed cathodic arc. Controlling the spacing between cathode spots enabled a correlation between a reduction in the mean charge state and an increase in the spacing of cathode spots to be observed. As the cathode current was increased, the distances between spots were reduced and these charge states were produced for longer times. Strong cathode spot coupling is proposed as a mechanism for the production of high charge states.
Reducing Water Permeability while Maintaining Transparency of PET: A Plasma Immersion Ion Implantation Study
Publisher: Wiley
Date: 06-11-2008
Large Core Fibers for Short-Distance Communication in Radiation Fields
Publisher: IEEE
Date: 06-2007
Doping of highly tetrahedral amorphous carbon
Publisher: Elsevier BV
Date: 12-1993
New plasma-assisted deposition technique using helicon activated reactive evaporation
Publisher: AIP Publishing
Date: 04-1995
DOI: 10.1063/1.1145576
Abstract: The helicon assisted reactive evaporation is a new plasma assisted reactive evaporation device that combines an evaporation source (electron-beam evaporator) and a high density plasma source (helicon plasma source), in a coaxial configuration where the evaporant material is transported through the plasma source. Evaporating silicon into an oxygen plasma yields a deposition rate of silica onto a 100-mm-diam substrate of 200 nm/min, with a refractive index identical to that of thermal silicon dioxide (1.46). This configuration is expected to have advantages over both plasma enhanced chemical vapor deposition and ion assisted deposition techniques, without exhibiting the serious drawback of requiring the handling of hazardous chemical precursors. Initial results show that the electron beam can be run in conjunction with the high density helicon plasma (1012 cm−3).
Electronic conductance of ion implanted and plasma modified polymers
Publisher: AIP Publishing
Date: 30-07-2007
DOI: 10.1063/1.2761233
Abstract: The authors used the plasma immersion ion implantation and deposition technique to modify polyethylene terephthalate (PET) and by using conductive atomic force microscope, the spatial distribution of ∼10nm size titanium nanoclusters embedded in PET matrices were observed. The I-V plots showed typical metal-semiconductor junction conductivity between the conductive tip and the surface. In addition, the authors also measured the temperature dependent conductivity and fitted it well to the Mott law, which implied that the conductance arose from electron hopping process. Such technique to create the surface structure of metal olymer nanocomposites may open an alternative way for plastic nanoelectronics.
The physics of confined flow and its application to water leaks, water permeation and water nanoflows: a review
Publisher: IOP Publishing
Date: 02-2016
DOI: 10.1088/0034-4885/79/2/025901
Abstract: This review assesses the current state of understanding of the calculation of the rate of flow of gases, vapours and liquids confined in channels, in porous media and in permeable materials with an emphasis on the flow of water and its vapour. One motivation is to investigate the relation between the permeation rate of moisture and that of a noncondensable test gas such as helium, another is to assist in unifying theory and experiment across disparate fields. Available theories of single component ideal gas flows in channels of defined geometry (cylindrical, rectangular and elliptical) are described and their predictions compared with measurement over a wide range of conditions defined by the Knudsen number. Theory for two phase flows is assembled in order to understand the behaviour of four standard water leak configurations: vapour, slug, Washburn and liquid flow, distinguished by the number and location of phase boundaries (menisci). Air may or may not be present as a background gas. Slip length is an important parameter that greatly affects leak rates. Measurements of water vapour flows confirm that water vapour shows ideal gas behaviour. Results on carbon nanotubes show that smooth walls may lead to anomalously high slip lengths arising from the properties of 'confined' water. In porous media, behaviour can be matched to the four standard leaks. Traditional membrane permeation models consider that the permeant dissolves, diffuses and evaporates at the outlet side, ideas we align with those from channel flow. Recent results on graphite oxide membranes show ex les where helium which does not permeate while at the same time moisture is almost unimpeded, again a result of confined water. We conclude that while there is no a priori relation between a noncondensable gas flow and a moisture flow, measurements using helium will give results within two orders of magnitude of the moisture flow rate, except in the case where there is anomalous slip or confined water, when moisture specific measurements are essential.
Mutations in DCC cause isolated agenesis of the corpus callosum with incomplete penetrance
Publisher: Springer Science and Business Media LLC
Date: 27-02-2017
DOI: 10.1038/NG.3794
Detecting and exploring partially unfolded states of proteins using a sensor with chaperone bound to its surface
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.BIOS.2008.07.076
Abstract: We have developed a sensor concept capable of discriminating environments that induce proteins to enter unfolding intermediate states. Such a sensor detects the presence of environmental stressors such as chemical agents in aqueous media, thermal stress or the presence of ionizing or non-ionizing radiation by monitoring the conformation state of a "sensor protein". In this paper, we demonstrate the concept by using surface plasmon resonance to monitor binding of thermally and chemically stressed sensor proteins to a chaperone, alpha-crystallin, bound to the sensor surface. Citrate synthase and insulin were used as ex le sensor proteins to detect the presence of thermal stress and chemical stress, respectively. It was shown that alpha-crystallin retained its chaperone action after immobilization on the Biacore sensor chip. The binding of early and late unfolding intermediates of citrate synthase was discriminated using the association and dissociation behaviour of the binding. The sensor is therefore capable of assessing the severity of an environmental stress.
Cathode-Spot Dynamics in a High-Current Pulsed Arc: A Noise Study
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2009
The gray body approximation for radiative heat transfer in evacuated tube solar collectors: Effects of envelope infrared transparency
Publisher: AIP Publishing
Date: 24-03-2022
DOI: 10.1063/5.0085363
Abstract: A theoretical and experimental analysis is carried out of radiative heat transfer in the coaxial geometry of evacuated tube solar collectors. The gray body approximation implicit in the use of an effective emissivity does not strictly apply to evacuated tube solar collectors due to selective absorber coating and partially transmitting outer glass in the thermal infrared, especially when constructed from borosilicate. We develop analytic expressions for the heat transfer through the outer envelope and show the equations no longer follow a simple form where an effective emissivity for the system can be defined. To test all approximations in practice, an experiment is performed using an evacuated solar collector manufactured in the 1980s by the Nitto Kohki company in Japan using the effective emissivity approximation to determine the typical heat transfer characteristics using net radiative heat flows in both directions. This method enabled a good fit to temperature–time data for cooling and heating of the inner tube for temperatures between 10 and 85 °C. The results confirm that the effective emittance method can be used in situations with typical glass wall thickness and temperatures. At temperatures greater 100 °C, the spectral distribution of the emitted radiation falls significantly within the transmitting region of the outer glass and can no longer be neglected. The work has verified the stability of the vacuum in this type of collector as the tube still functions well, maintaining a low emissivity and good vacuum after approximately 40 years in storage conditions.
Binding of the cell adhesive protein tropoelastin to PTFE through plasma immersion ion implantation treatment
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.BIOMATERIALS.2011.03.079
Abstract: The interaction of proteins and cells with polymers is critical to their use in scientific and medical applications. In this study, plasma immersion ion implantation (PIII) was used to modify the surface of polytetrafluorethylene (PTFE), enabling the covalent binding of a cell adhesive protein, tropoelastin, without employing chemical linking molecules. Tropoelastin coating of untreated or PIII treated PFTE simultaneously promoted and blocked cell interactions respectively, i.e. PIII treatment of the PTFE surface completely inverses the cell interactive properties of bound tropoelastin. This activity persisted over long term storage of the PIII treated surfaces. The integrin binding C-terminus of tropoelastin was markedly less solvent exposed when bound to PIII treated PTFE than untreated PTFE, accounting for the modulation of cell adhesive activity. This presents a new methodology to specifically modulate cell behavior on a polymer surface using a simple one step treatment process, by adjusting the adhesive activity of a single extracellular matrix protein.
Molecular adsorption on silicon (001): A systematic evaluation of size effects in slab and cluster models
Publisher: AIP Publishing
Date: 04-2013
DOI: 10.1063/1.4802837
Abstract: First-principles calculations are in wide use today to describe chemical processes occurring on the silicon (001) surface. The number of atoms that can be explicitly treated is limited and hence size-constraints are invariably required this applies to both cluster and periodic slab approaches. Using a trial set of seven molecular adsorbateconfigurations, we examine the dependence of calculated adsorption energies on several size parameters, namely thickness and in-plane unit cell size for slab models, as well as thickness, length, and width for cluster models. Size-converged adsorption energies are estimated by extrapolation, and are used to assess the accuracy of the more typically-sized slabs and clusters in common use today. Use of a DFT method that can be applied to both slabs and clusters allows us to assess the performance of these two approaches on an equal footing.
Optimal process parameters for thermoplastic polyetheretherketone joints fabricated using transmission laser welding and Lumogen® IR absorptive pigment
Publisher: Laser Institute of America
Date: 02-2011
DOI: 10.2351/1.3552972
Abstract: This study investigates the effects of the process parameters (laser power and irradiation time) on the bond quality of transmission laser welded polyetheretherketone. Commercially available Lumogen® IR pigment was added to the bulk of the polymer for laser absorption. Quasisimultaneous beam configuration was used to weld injection molded s les of 0.7 mm thickness in a lap joint configuration. Combinations of laser power (40–80 W) and irradiation times (10–50 s) were investigated. The laser power was found to have the most effect on weld strength, while irradiation time did not have a marked effect on weld strength. At optimal process conditions, the weld strength ranged from 20 to 45 MPa. High variability in weld strength was seen within groups with identical process parameters and was attributed to the variability in material morphology as a result of injection molding. X-ray tomography was utilized to view intact weld interfaces. A significant finding was the presence of voids (up to 0.5 mm diameter) at the weld interface.
Long term performance of evacuated tubular solar water heaters in Sydney, Australia
Publisher: Elsevier BV
Date: 1984
The role of pulse length in target poisoning during reactive HiPIMS: application to amorphous HfO2
Publisher: IOP Publishing
Date: 26-05-2015
Autohesion of semi-crystalline PEEK near and under the glass transition temperature
Publisher: Elsevier BV
Date: 10-2013
Plasma treatments of dressings for wound healing: a review
Publisher: Springer Science and Business Media LLC
Date: 02-10-2017
Comment on Transformation of C-type defects on Si(100)-2 x 1 surface at room temperature STM/STS study [Surf, Sci. 602 (2008) 2835]
Publisher: Elsevier BV
Date: 2010
Gap states, doping and bonding in tetrahedral amorphous carbon
Publisher: Elsevier BV
Date: 05-1995
Electrostatic and optical resonances of arrays of cylinders
Publisher: Springer Science and Business Media LLC
Date: 11-1980
DOI: 10.1007/BF00914904
Evolution of target condition in reactive HiPIMS as a function of duty cycle: An opportunity for refractive index grading
Publisher: AIP Publishing
Date: 07-03-2017
DOI: 10.1063/1.4977824
Abstract: Competition between target erosion and compound layer formation during pulse cycles in reactive HiPIMS opens up the possibility of tuning discharge conditions and the properties of deposited films by varying the duty cycle in situ without altering the reactive gas mixture. Three different reactive systems, hafnium in oxygen, tungsten in oxygen, and tungsten in oxygen/nitrogen, are studied in which amorphous films of hafnium oxide (HfO2), tungsten oxide (WO3), and tungsten oxynitride (WOxNy) are deposited. We show that the cyclic evolution of the target surface composition depends on the properties of the target including its affinity for the reactive gas mix and the compound layer melting point and volatility. We find that pulse length variations modulate the target compound layer and hence the discharge chemistry and properties of the films deposited. The refractive indices of HfO2 and WO3 were progressively reduced with the duty cycle, whereas that of WOxNy increased. These variations were found to be due to changes in the chemical composition and/or densification. We present and validate a phenomenological model that explains these findings in terms of a compound layer on the target surface that undergoes evolution during each pulse resulting in a cyclic equilibrium. The end points of the composition of the target surface depend on the duty cycle. Tuning the pulse characteristics holds great promise for the fabrication of multilayer films with through thickness graded properties.
Using ELNES with parallel EELS for differentiating between a-Si:X thin films
Publisher: Elsevier BV
Date: 10-1989
Structural Analysis and Protein Functionalization of Electroconductive Polypyrrole Films Modified by Plasma Immersion Ion Implantation
Publisher: American Chemical Society (ACS)
Date: 30-08-2017
Dosimetric consequences of gold nanoparticle clustering during photon irradiation
Publisher: Wiley
Date: 06-11-2017
DOI: 10.1002/MP.12620
Abstract: The radiation dose enhancement caused by introducing gold nanoparticles (GNP) into cells can increase the dose locally absorbed. A disconnect between experimentally determined survival and dose enhancements predicted by Monte Carlo simulations on macroscopic scales, suggests small-scale energy deposition patterns play an important role in GNP dose enhancement. Clustering of the GNPs could potentially alter small-scale energy deposition patterns. Here we use Monte Carlo simulations to quantify energy deposition patterns in the presence of clustered GNPs and address the question of whether clustering of the nanoparticles affects the energy deposition patterns and ultimately cellular response. Using the PENELOPE Monte Carlo code, we examine the absorption of energy in the environment of a single irradiated GNP following its interaction with a set of primary monoenergetic photon beams. We introduce successive GNPs to form a cluster about the particle in which the primary photon interactions occur and report on the energy deposited locally (within a 500 nm radius) and nonlocally (beyond 500 nm) in the surrounding water-equivalent medium as a function of the number of additional GNPs and the packing geometry they assume. When additional GNPs cluster in tightly packed formations about a GNP in which an incident photon interacts, both the energy deposited locally and released nonlocally are reduced relative to the case where other GNPs are not present. The degree of the reduction depends on incident photon energy, the number of GNPs added to the cluster, and the packing geometry. With 90 additional GNPs in a hexagonal close packing (HCP) cluster about a directly irradiated test particle, the local energy deposition was reduced to 29% (of the value in the absence of neighbors) in the most extreme monoenergetic case. Energy released into the nonlocal volume was most affected by the cluster for low-incident photon energies (< 40 keV), where reductions to 26% of the value in the absence of a cluster were shown. The packing geometry mitigated these results. When the irradiated GNP was on the periphery of the HCP cluster, or when the cluster was confined to a plane, the observed effects were weaker and when an equal number of GNPs were uniformly distributed in the local volume, the changes were trivial (less than 2%). The findings provide grounds for reconciling the observations of cell survival with Monte Carlo predictions of GNP dose enhancement. This work is significant because it demonstrates that GNP clustering needs to be understood and accounted to optimize local dose enhancement.
HiPIMS carbon coatings show covalent protein binding that imparts enhanced hemocompatibility
Publisher: Elsevier BV
Date: 11-2018
Dark field microscopy for diffraction analysis of amorphous carbon solids
Publisher: Elsevier BV
Date: 03-2005
Molecular dynamics simulation of the thermal spike in amorphous carbon thin films
Publisher: Elsevier BV
Date: 03-2005
Electric probe measurements of high-voltage sheath collapse in cathodic arc plasmas due to surface charging of insulators
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2003
The mechanical properties of energetically deposited non-crystalline carbon thin films
Publisher: Elsevier BV
Date: 03-2016
Control of stress and microstructure in cathodic arc deposited films
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2003
Corrections to Graham’s Law of Effusion for Predicting Leak Rates Through Hermetic Seals
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2017
Controlled glow to arc transition in sputtering for high rate deposition of carbon films
Publisher: Elsevier BV
Date: 02-2011
Extraction of structural information from measured transport properties of composites
Publisher: Springer Science and Business Media LLC
Date: 09-1982
DOI: 10.1007/BF00618111
Mobile phones, heat shock proteins and cancer
Publisher: Elsevier BV
Date: 06-2001
DOI: 10.1046/J.1432-0436.2001.670401.X
Abstract: There are several reports which indicate that electromagnetic radiation (such as from mobile phones) at non-thermal levels may elicit a biological effect in target cells or tissues. Whether or not these biological effects lead to adverse health effects, including cancer, is unclear. To date there is limited scientific evidence of health issues, and no mechanism by which mobile phone radiation could influence cancer development. In this paper, we develop a theoretical mechanism by which radiofrequency radiation from mobile phones could induce cancer, via the chronic activation of the heat shock response. Upregulation of heat shock proteins (Hsps) is a normal defence response to a cellular stress. However, chronic expression of Hsps is known to induce or promote oncogenesis, metastasis and/or resistance to anticancer drugs. We propose that repeated exposure to mobile phone radiation acts as a repetitive stress leading to continuous expression of Hsps in exposed cells and tissues, which in turn affects their normal regulation, and cancer results. This hypothesis provides the possibility of a direct association between mobile phone use and cancer, and thus provides an important focus for future experimentation.
Thermodynamic Interpretation of the Meyer-Neldel Rule Explains Temperature Dependence of Ion Diffusion in Silicate Glass
Publisher: American Physical Society (APS)
Date: 21-10-2022
The effect of plasma immersion ion implantation on the contact pressure and composition of titanium nitride thin films
Publisher: Elsevier BV
Date: 09-2006
Nanosecond Responses of Proteins to Ultra-High Temperature Pulses
Publisher: Elsevier BV
Date: 09-2006
Dynamic modeling of lung tumor motion during respiration
Publisher: IOP Publishing
Date: 20-04-2011
DOI: 10.1088/0031-9155/56/10/007
Abstract: A dynamic finite element model of the lung that incorporates a simplified geometry with realistic lung material properties has been developed. Observations of lung motion from respiratory-gated computed tomography were used to provide a database against which the predictions of the model are assessed. Data from six patients presenting with lung tumors were processed to give sagittal sections of the lung containing the tumor as a function of the breathing phase. Statistical shape modeling was used to outline the diaphragm, the tumor volume and the thoracic wall at each breathing phase. The motion of the tumor in the superior-inferior direction was plotted against the diaphragm displacement. The finite element model employed a simplified geometry in which the lung material fills a rectangular volume enabling two-dimensional coordinates to be used. The diaphragm is represented as a piston, driving the motion. Plots of lung displacement against diaphragm displacement form hysteresis loops that are a sensitive indicator of the characteristics of the motion. The key parameters of lung material that determine the motion are the density and elastic properties of lung material and the airway permeability. The model predictions of the hysteresis behavior agreed well with observation only when lung material is modeled as viscoelastic. The key material parameters are suggested for use as prognostic indicators of the progression of disease and of changes arising from the response of the lung to radiation treatment.
Determination of the equilibrium ion sheath in the drifting plasma by numerical simulation
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2003
Wannier function analysis of silicon carbon alloys
Publisher: IOP Publishing
Date: 18-12-2002
Influence of pH on yeast immobilization on polystyrene surfaces modified by energetic ion bombardment
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.COLSURFB.2012.11.029
Abstract: Plasma immersion ion implantation (PIII) treatment is a novel method for immobilizing yeast on polymer surfaces by covalent linkage. This study of the immobilization of Saccharomyces cerevisiae in both rehydrated and cultured forms showed that the density of cell attachment on PIII treated polystyrene (PS) was strongly dependent on the pH of the incubation medium and was higher for rehydrated yeast. A study of the surface charge was undertaken to explain this result. A high density of cell attachment occurs in acidic conditions (pH 3-5) and a significantly reduced cell density occurs in neutral and alkaline buffers (pH 6-10) for both types of yeast. Force measurements using atomic force microscopy show that a negative charge is present on polystyrene after PIII treatment. The charge is close to zero at pH 3 to pH 5 and increasingly negative from pH 6 to pH 10. Both rehydrated yeast and cultured yeast have negative electrophoretic mobility in the pH range studied. The repulsive forces are weak in acidic buffers and stronger in neutral and alkaline buffers, in good agreement with the cell densities observed. Rehydrated yeast cells are found to be more hydrophobic than cultured yeasts in the same buffer. The higher hydrophobicity explains the higher attachment of rehydrated yeast compared to cultured yeast.
Comparison of density-functional, tight-binding, and empirical methods for the simulation of amorphous carbon
Publisher: American Physical Society (APS)
Date: 25-01-2002
Use of low energy and high frequency PBII during thin film deposition to achieve relief of intrinsic stress and microstructural changes
Publisher: Elsevier BV
Date: 08-2004
A New Surface for Immobilizing and Maintaining the Function of Enzymes in a Freeze-Dried State
Publisher: American Chemical Society (ACS)
Date: 30-07-2009
DOI: 10.1021/BM900523M
Abstract: We describe a new surface produced by plasma treatment for immobilizing proteins in the dry state. The need for surfaces suitable for immobilizing proteins is increasing because of demand for microarray diagnostic services, biosensors, and chemical processing. Storage of surface attached proteins in the dry state offers benefits of long shelf life, protection from proteases, easier transportation and convenient storage. In this work, we produced plasma-modified polyethylene surfaces and tested them using two important enzymes for which convenient functional assays are available, namely, horseradish peroxidase and catalase. Over 80% of the function of horseradish peroxidase is retained after freeze-drying, and this function is unaltered after 4 months of storage at 4 degrees C on the treated polyethylene surface. The factors important for maintenance of surface attached enzyme stability were (1) plasma immersion ion implantation (PIII) treatment of the surface, (2) freeze-drying with sucrose in the buffer solution, (3) dry storage with desiccant, and (4) maintaining the freeze-dried protein at a reduced temperature. Other than sucrose, no other additives are needed.
The structure and properties of ion-beam-synthesized boron nitride films
Publisher: AIP Publishing
Date: 15-10-1988
DOI: 10.1063/1.341357
Abstract: Films containing boron and nitrogen were prepared by electron-beam evaporation of boron and bombardment of the growing film with nitrogen ions of energy up to 1500 eV. Hard films of high transparency (extinction coefficient & .01) were prepared with nitrogen-to-boron atomic arrival ratios greater than one. The optical constants in the visible part of the spectrum were determined as a function of B-to-N atomic ratio in the film and substrate temperature using optical photometry. Measurements of the optical constants were extended to 40 eV using a Kramers–Kronig analysis of electron-energy-loss spectra. Boron-to-nitrogen atomic arrival rates were determined and show that as ion energy and substrate temperature are increased ion flux must be increased to achieve the same stoichiometry. Film structure was imaged using high-resolution electron microscopy, and the radial distribution function (RDF) was determined. The RDF of stoichiometric films showed that high substrate temperatures increased the size of the ordered regions. The RDF and high-resolution imaging of all films were consistent with the presence of the hexagonal form of BN with substoichiometric films containing amorphous boron as the other constituent. This conclusion is consistent with the analysis derived from the sum rule obtained from the optical constants. No evidence could be found for the cubic form of BN.
Ab initio studies of amorphous carbon films
Publisher: Elsevier BV
Date: 08-2005
Intrinsic stress induced by substrate bias in amorphous hydrogenated silicon thin films
Publisher: Elsevier BV
Date: 08-2005
Sensory gating in bilayer amorphous carbon memristors
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8NR05328F
Abstract: Paired pulse inhibition is observed using amorphous carbon memristors, which enables their use for sensory gating.
Direct Determination of Total Hemispherical Emittance of Perovskite and Silicon Solar Cells
Publisher: Elsevier BV
Date: 2020
The structure and annealing properties of multilayer carbon films
Publisher: Elsevier BV
Date: 08-2005
A combinatorial investigation of sputtered Ta–Al–C thin films
Publisher: Elsevier BV
Date: 05-2014
Optimal coupling of light from a cylindrical scintillator into an optical fiber
Publisher: Optica Publishing Group
Date: 04-01-2007
DOI: 10.1364/AO.46.000397
Abstract: Radiation dose measurements based on scintillator detection are conveniently made by coupling the light from the scintillator into an optical fiber. The low light levels involved typically require sensitive photodetectors, so it is advantageous to increase the available signal by optimizing the optical coupling efficiency between the scintillator and optical fiber. We model this process using geometric optics and finite-element ray tracing to determine the features that maximize the amount of light coupled to an optical fiber from a cylindrical scintillator. We also address whether the coupling can be improved by using an intermediate optical element such as a lens, and we provide a means for calculating its required optical properties for a given geometry.
A mathematical framework for separating the direct and bystander components of cellular radiation response
Publisher: Informa UK Limited
Date: 28-05-2010
On the use of test gases of various radii to investigate molecular sieving in leak channels
Publisher: IEEE
Date: 08-2015
Gold, silver, chromium, and copper cermet selective surfaces for evacuated solar collectors
Publisher: AIP Publishing
Date: 1979
DOI: 10.1063/1.90585
Abstract: Cermet solar selective surfaces of absorptance over 0.90 and emittance less than 0.05 have been prepared by vacuum coevaporation of alumina and spinel with gold, silver, chromium, and copper. Grading of commposition was employed to enhance the absorptance. The effect of heat treatment in vacuum up to 500 °C was studied and the chromium-alumina cermet shown to be the best candidate for vacuum-insulated collectors.
Control of stress and delamination in single and multi-layer carbon thin films prepared by cathodic arc and RF plasma deposition and implantation
Publisher: Elsevier BV
Date: 06-2006
Comment on ‘Shear stiffness in nanolaminar Ti3SiC2challengesab initiocalculations’
Publisher: IOP Publishing
Date: 13-06-2011
DOI: 10.1088/0953-8984/23/26/268001
Abstract: In a recent publication by Kisi et al (2010 J. Phys.: Condens. Matter 22 162202) the authors present experimentally measured elastic constants for the M(n + 1)AX(n) (MAX) phase, Ti(3)SiC(2), that differ from density functional theory calculations. They then conclude that 'prediction [by ab initio calculation] of the full elasticity tensor for Ti(3)SiC(2) has not been successful'. However the authors do not compare with previous experimental work in which Finkel et al measure the elastic moduli (Finkel et al 2000 J. Appl. Phys. 87 1701). The predictions of ab initio calculations (Yu et al 2005 J. Mater. Res. 20 1180) agree with the measurements of Finkel et al as well as with most other experimentally measured elastic moduli for MAX phases (Cover et al 2008 10 935 Cover et al 2009 J. Phys.: Condens. Matter 21 305403). The unrealistically high value of the C(44) constant obtained by Kisi et al, which would mean that Ti(3)SiC(2) is almost as resistant to shear as diamond, undermines confidence in their results.
Surface adsorption and wetting properties of amorphous diamond-like carbon thin films for biomedical applications
Publisher: Elsevier BV
Date: 06-2008
Cell patterning via linker-free protein functionalization of an organic conducting polymer (polypyrrole) electrode
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.ACTBIO.2012.03.023
Abstract: The interaction of proteins and cells with polymers is critical to their use in scientific and medical applications. In this study, plasma immersion ion implantation (PIII) was used to modify the surface of the conducting polymer, polypyrrole, which possesses electrical properties. PIII treatment enabled persistent, covalent binding of the cell adhesive protein, tropoelastin, without employing chemical linking molecules. In contrast tropoelastin was readily eluted from the untreated surface. Through this differential persistence of binding, surface bound tropoelastin supported cell adhesion and spreading on the PIII treated but not the untreated polypyrrole surface. The application of a steel shadow mask during PIII treatment allowed for spatial definition of tropoelastin exclusively to PIII treated regions. The general applicability of this approach to other extracellular matrix proteins was illustrated using collagen I, which displayed similar results to tropoelastin but required extended washing conditions. This approach allowed fine patterning of cell adhesion and spreading to tropoelastin and collagen, specifically on PIII treated polypyrrole regions. We therefore present a methodology to alter the functionality of polypyrrole surfaces, generating surfaces that can spatially control cellular interactions through protein functionalization with the potential for electrical stimulation.
Ellipsometry analysis of conformational change of immobilized protein monolayer on plasma polymer surfaces
Publisher: Elsevier BV
Date: 02-2011
Real-time monitoring and diagnosis of scintillation dosimeters using an ultraviolet light emitting diode
Publisher: IOP Publishing
Date: 09-04-2008
DOI: 10.1088/0031-9155/53/9/007
Abstract: Plastic scintillator fibre optic dosimeters (FODs) have advantages for both brachytherapy and external beam radiotherapy applications. Convenient real-time monitoring and diagnosis of such dosimeters are desirable because of changes in the optical circuit that may arise in use. In this paper, we propose and demonstrate a real-time method using ultraviolet light emitting diodes (LED) to stimulate the scintillator and to diagnose failures of FODs. Key aspects of the LED FOD dosimetry design are investigated, enabling the design of a stable and accurate real-time monitoring dosimetry system. We demonstrate experimentally that the real-time monitoring FOD system is convenient to be used to monitor FOD dosimeters and to diagnose their failures resulted from different mechanisms.
Recent progress and future prospects of perovskite tandem solar cells
Publisher: AIP Publishing
Date: 15-10-2021
DOI: 10.1063/5.0061483
Abstract: Organic–inorganic metal halide perovskite solar cells represent the fastest advancing solar cell technology in terms of energy conversion efficiency improvement, as seen in the last decade. This has become a promising technology for next-generation, low-cost, high-efficiency photovoltaics including multi-junction tandem cell concepts. Double-junction tandem cells have much higher efficiency limits of 45%, beyond the Shockley–Queisser limits for a single-junction solar cell. In this review, recent progress with the perovskite tandem solar cells is highlighted, in particular, with 2-terminal perovskite–Si, perovskite–CIGS [where CIGS = Cu(In,Ga)(S,Se)2], perovskite–organic photovoltaic, perovskite–perovskite, and 3-junction-perovskite tandems. The opportunity and challenges of two-terminal monolithic perovskite tandems are discussed including a roadmap of strategies for further improving their efficiencies.
Bonding statistics and electronic structure of novel Si–B–C–N materials: Ab initio calculations and experimental verification
Publisher: American Vacuum Society
Date: 08-2007
DOI: 10.1116/1.2764081
Abstract: Amorphous silicon-boron-carbon-nitrogen alloys were deposited by reactive magnetron sputtering, and their bonding statistics and electronic structure were investigated using a combined approach of experiment and molecular dynamics simulations. The authors show a difference between Si-based and C-based Si–B–C–N networks, and investigate coordination numbers and behavior of in idual atom types. Furthermore, the authors calculate electronic structure and photoconductivity of the materials. The authors find that both a higher Si∕C ratio and an addition of hydrogen increase a band gap of the materials.
Energetic deposition of carbon in a cathodic vacuum arc with a biased mesh
Publisher: AIP Publishing
Date: 04-2011
DOI: 10.1063/1.3562165
Abstract: Carbon films were deposited in a filtered cathodic vacuum arc with a bias potential applied to a conducting mesh mounted in the plasma stream between the source and the substrate. We determined the stress and microstructural properties of the resulting carbon films and compared the results with those obtained using direct substrate bias with no mesh. Since the relationship between deposition energy and the stress, sp2 fraction and density of carbon are well known, measuring these film properties enabled us to investigate the effect of the mesh on the energy and composition of the depositing flux. When a mesh was used, the film stress showed a monotonic decrease for negative mesh bias voltages greater than 400V, even though the floating potential of the substrate did not vary. We explain this result by the neutralization of some ions when they are near to or passing through the negatively biased mesh. The microstructure of the films showed a change from amorphous to glassy carbonlike with increasing bias. Potential applications for this method include the deposition of carbon films with controlled stress on low conductivity substrates to form rectifying or ohmic contacts.
Cathode spot phenomena in titanium vacuum arcs
Publisher: AIP Publishing
Date: 15-07-1989
DOI: 10.1063/1.343566
Abstract: Investigations of cathode spot behavior on a titanium cathode in the presence of a variable magnetic field are presented. The cathode spot velocity as a function of magnetic field strength, arc current, and gas pressure has been determined using an optical technique, and the results have been compared with a number of available theories. The cathode spots have been investigated using a magnetic probe coil, and using both high-speed and conventional photography. The observations show that the motion of the spots is consistent with the presence of a positive space charge at the spot.
Temperature Activated Diffusion of Radicals through Ion Implanted Polymers
Publisher: American Chemical Society (ACS)
Date: 19-11-2015
Abstract: Plasma immersion ion implantation (PIII) is a promising technique for immobilizing biomolecules on the surface of polymers. Radicals generated in a subsurface layer by PIII treatment diffuse throughout the substrate, forming covalent bonds to molecules when they reach the surface. Understanding and controlling the diffusion of radicals through this layer will enable efficient optimization of this technique. We develop a model based on site to site diffusion according to Fick's second law with temperature activation according to the Arrhenius relation. Using our model, the Arrhenius exponential prefactor (for barrierless diffusion), D0, and activation energy, EA, for a radical to diffuse from one position to another are found to be 3.11 × 10(-17) m(2) s(-1) and 0.31 eV, respectively. The model fits experimental data with a high degree of accuracy and allows for accurate prediction of radical diffusion to the surface. The model makes useful predictions for the lifetime over which the surface is sufficiently active to covalently immobilize biomolecules and it can be used to determine radical fluence during biomolecule incubation for a range of storage and incubation temperatures so facilitating selection of the most appropriate parameters.
High dose-rate brachytherapy source localization: Positional resolution using a diamond detector
Publisher: IOP Publishing
Date: 02-07-2003
DOI: 10.1088/0031-9155/48/14/307
Abstract: A potential real-time source position verification process for high dose-rate (HDR) brachytherapy treatment is described. This process is intended to provide immediate confirmation that a treatment is proceeding according to plan, so that corrective action can be taken if necessary. We show that three dosimeters are in principle sufficient and demonstrate the feasibility of the process using a diamond detector and an Ir-192 source. An error analysis including all identified sources of error shows that this detector is capable of locating the distance to the source to within 2 mm for distances up to 12 cm. This positional accuracy is less than the diameter of typical HDR catheters indicating that a diamond detector can be used to accurately determine the distance to the source. The uncertainty in the distance is found to increase with distance.
Transmission laser welding of amorphous and semi-crystalline poly-ether–ether–ketone for applications in the medical device industry
Publisher: Elsevier BV
Date: 12-2010
Deposition of a-C:N films and evaluation of their robustness in electrochemical applications
Publisher: Elsevier BV
Date: 06-2008
The importance of bias pulse rise time for determining shallow implanted dose in plasma immersion ion implantation
Publisher: AIP Publishing
Date: 18-03-2003
DOI: 10.1063/1.1563063
Abstract: The composition of the low-energy ions arising from the rise and fall time periods of the voltage pulse in plasma immersion ion implantation (PIII) are simulated by particle-in-cell (PIC) modeling. It is shown that more than 70% of the low-energy ions with an energy corresponding to less than half of the applied voltage come from the short rise time period. Although the fall time period is typically 30 times longer than the rise time, less than 25% of the low-energy ions originate from it. Based on the PIC results, the depth profile of the implanted ions is derived using the Monte-Carlo code SRIM2000 [J. F. Ziegler, The Stopping and Range of Ions in Solids (Pergamon, New York, 1985)]. The low-energy ions are found to be implanted to a much shallower depth than ions introduced during the fall time period the concentration profile which decays more sharply into the bulk. These results indicate that the most effective way to reduce or increase the surface concentration is by adjusting the rise time of the PIII voltage pulse. This will require a power supply capable of fast rise times and good matching between power supply and load.
A method to remove residual signals in fibre optic luminescence dosimeters
Publisher: IOP Publishing
Date: 15-02-2013
DOI: 10.1088/0031-9155/58/5/1581
Abstract: Whenever a fibre optic is used to convey a light signal through a radiation field, it is likely that an unwanted background signal will arise from Cerenkov or fluorescent light which will contaminate the signal. In luminescence dosimetry of high energy beams, when a fibre optic is used to convey the signal from the radiation field to the detector, Cerenkov light is the dominant contributor to the background signal and must be corrected for. In this work, a novel method is demonstrated to separate the signal from the unwanted background. A remotely operated shutter is used to block the signal, allowing the residual background in the fibre optic to be quantified. This background is subtracted from the total measurement acquired in a subsequent irradiation, enabling the luminescence signal to be extracted. Two types of shutter mechanism are considered: an electro-mechanical device to intercept the light path and an LCD device to block the light by cross-polarization. Both shutters were characterized and incorporated into a fibre optic dosimetry system used to measure the radiation dose produced by external beam radiation linear accelerators. The dosimeter using each of the shutters in turn was exposed to a 6 MV photon beam to determine their performance, including the measurement of field size dependent output factors. The mechanical shutter determined the output factors to within 0.29% of those measured with an ionization chamber, whereas the LCD shutter gave results that deviated by up to 2.4%. The switching precision of both shutters was good with standard deviations of less than 0.25% and both were able to completely block the light signal when closed. The use of shutters could therefore be applied to any fibre optic based system to quantify and remove a reproducible background arising from any source including ambient, fluorescent and Cerenkov light.
Microstructure of zi rcon is films deposited with ion assistance
Publisher: Springer Science and Business Media LLC
Date: 10-1987
DOI: 10.1007/BF01161485
Stress relief and texture formation in aluminium nitride by plasma immersion ion implantation
Publisher: IOP Publishing
Date: 03-2004
Erratum: Electronic structure models of phosphorusδ
Publisher: American Physical Society (APS)
Date: 02-07-2009
Monte Carlo calculation of the thermalization of atoms sputtered from the cathode of a sputtering discharge
Publisher: AIP Publishing
Date: 05-1989
DOI: 10.1063/1.342593
Abstract: The Monte Carlo technique has been used to simulate the thermalization of sputtered atoms in the filling or background gas within a planar sputtering discharge. The model uses Thompson’s theoretical distribution of the energy of atoms sputtered from the cathode surface together with an approximation to the 6–12 Lennard–Jones potential to describe collisions between sputtered atoms and background gas atoms. The diffusion of the thermalized atoms is included explicitly in the Monte Carlo calculations. The velocity distribution of sputtered atoms between the cathode and substrate is calculated, from which their average kinetic energy is determined as a function of the product Pd, where P is the background gas pressure and d is the distance from the cathode. Because of the effect of the finite cathode-substrate separation on back diffusion, it was found that PD, where D is the cathode-to-substrate separation, is an important parameter in describing thermalization and, consequently, the average energy of sputtered atoms throughout the discharge. These calculations are compared with theoretical analyses of other workers and show good agreement with experimental results.
Optimisation of exposure conditions for in vitro radiobiology experiments
Publisher: Springer Science and Business Media LLC
Date: 28-03-2012
DOI: 10.1007/S13246-012-0132-6
Abstract: Despite the long history of using cell cultures in vitro for radiobiological studies, there is to date no study specifically addressing the dosimetric implications of flask selection and exposure environment in clonogenic assays. The consequent variability in dosimetry between laboratories impedes the comparison of results. In this study we compare the dose to cells adherent to the base of three types of commonly used culture flasks or plates. The cells are exposed to a 6MV clinical photon beam using either an open or a half blocked field. The depth of medium in each flask is varied with the medium surrounding the flask either water or air. The results show that the dose to the cells is more affected by the scattering conditions surrounding the flasks than by the level of filling within the flask. It is recommended that water or a water equivalent phantom material is used to surround the flasks or plates to approximate full scatter conditions at the cell layer. However for modulated fields, surrounding the 24 well plates with water-equivalent material is inadequate because of the large volume of air surrounding in idual wells. Our results stress the importance of measuring the dose for new experimental configurations.
The design of broadband, wide-angle interference filters for solar concentrating systems
Publisher: Elsevier BV
Date: 07-2006
Grid therapy using high definition multileaf collimators: realizing benefits of the bystander effect
Publisher: Informa UK Limited
Date: 17-03-2017
Optimization of temporal dose modulation: Comparison of theory and experiment
Publisher: Wiley
Date: 17-05-2012
DOI: 10.1118/1.4712223
Abstract: To compare theoretical predictions and experimental measurements of cell survival after exposure to two different temporally modulated radiation dose patterns that deliver the same dose in the same overall time. The authors derived an analytic expression for the dose protraction factor G in the Lea-Catcheside formalism for cell survival for "triangle" and "V" temporal modulation of dose. These temporal dose patterns were used in experimental clonogenic studies of a melanoma cell line (MM576) and a nonsmall-cell lung cancer line (NCI-H460) that have different alpha, beta, and repair parameters. The overall treatment time and total dose were kept constant. The analytic expressions for G for the two temporal modulations are presented as a function of a single variable, the product of the exposure time, and the repair constant, enabling G to be evaluated for any exposure time and for any cell line. G for the triangle delivery pattern is always the larger. For the MM576 cell line, following a large dose of 6 Gy, a larger survival fraction was found for the V delivery pattern. No difference in survival was observed for lower doses or for the NCI-H460 cell line at any dose. These results are predicted by our theory, using published values of alpha, beta, and repair time within the limits of experimental uncertainty. The study provides evidence to confirm that cell lines having large beta values exhibit a response that is sensitive to the pattern of dose delivery when the delivery time is comparable with the repair time. It is recommended that the dose delivery pattern be considered in hypofractionated treatments.
Characterization of a large area scanning PECVD deposition system with small size RF electrodes
Publisher: Elsevier BV
Date: 09-2006
Optimization of solar selectivity in colloidally produced solar selective coatings
Publisher: Elsevier BV
Date: 11-1981
Thermal dissociation and desorption of PH3 on Si(001): A reinterpretation of spectroscopic data
Publisher: American Physical Society (APS)
Date: 08-11-2006
Automated cell colony counting and analysis using the circular Hough image transform algorithm (CHiTA)
Publisher: IOP Publishing
Date: 03-10-2008
DOI: 10.1088/0031-9155/53/21/007
Abstract: We present an automated cell colony counting method that is flexible, robust and capable of providing more in-depth clonogenic analysis than existing manual and automated approaches. The full form of the Hough transform without approximation has been implemented, for the first time. Improvements in computing speed have facilitated this approach. Colony identification was achieved by pre-processing the raw images of the colonies in situ in the flask, including images of the flask edges, by erosion, dilation and Gaussian smoothing processes. Colony edges were then identified by intensity gradient field discrimination. Our technique eliminates the need for specialized hardware for image capture and enables the use of a standard desktop scanner for distortion-free image acquisition. Additional parameters evaluated included regional colony counts, average colony area, nearest neighbour distances and radial distribution. This spatial and qualitative information extends the utility of the clonogenic assay, allowing analysis of spatially-variant cytotoxic effects. To test the automated system, two flask types and three cell lines with different morphology, cell size and plating density were examined. A novel Monte Carlo method of simulating cell colony images, as well as manual counting, were used to quantify algorithm accuracy. The method was able to identify colonies with unusual morphology, to successfully resolve merged colonies and to correctly count colonies adjacent to flask edges.
An energy landscape for carbon network solids
Publisher: Elsevier BV
Date: 11-2013
Clinical trials of a urethral dose measurement system in brachytherapy using scintillation detectors
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.IJROBP.2010.03.030
Abstract: To report on the clinical feasibility of a novel scintillation detector system with fiberoptic readout that measures the urethral dose during high-dose-rate brachytherapy treatment of the prostate. The clinical trial enrolled 24 patients receiving high-dose-rate brachytherapy treatment to the prostate. After the first 14 patients, three improvements were made to the dosimeter system design to improve clinical reliability: a dosimeter self-checking facility a radiopaque marker to determine the position of the dosimeter, and a more robust optical extension fiber. Improvements to the system design allowed for accurate dose measurements to be made in vivo. A maximum measured dose departure of 9% from the calculated dose was observed after dosimeter design improvements. Departures of the measured from the calculated dose, after improvements to the dosimetry system, arise primarily from small changes in patient anatomy. Therefore, we recommend that patient response be correlated with the measured in vivo dose rather than with the calculated dose.
Elastic properties of Tin+1AlCnand Tin+1AlNnMAX phases
Publisher: Wiley
Date: 10-2008
Diffusion pathways of phosphorus atoms on silicon (001)
Publisher: American Physical Society (APS)
Date: 15-04-2009
Electron optical characterization of cubic boron nitride thin films prepared by reactive ion plating
Publisher: AIP Publishing
Date: 15-09-1991
DOI: 10.1063/1.349330
Abstract: Boron nitride films prepared by reactive ion plating from a boron evaporation source were characterized structurally using three independent electron optical techniques: energy filtered electron diffraction with radial distribution function analysis electron energy-loss spectroscopy of the near-edge structure of the boron K edge and spectroscopy of the plasmon region of the energy-loss spectrum. Both specimens had a graded BNx layer between the BN layer and the silicon substrate and in addition one specimen had a titanium bonding layer underneath the BNx layer. The presence of c-BN in both specimens was confirmed by all techniques. The specimen with the titanium bonding layer was examined in cross section and showed essentially pure c-BN on the surface. A model for the formation of c-BN assisted by the compressive stress generated during deposition is proposed.
A simulation of gas flow: The dependence of the tangential momentum accommodation coefficient on molecular mass
Publisher: AIP Publishing
Date: 09-2016
DOI: 10.1063/1.4963102
Abstract: The tangential momentum accommodation coefficient (TMAC) influences the rate of pressure driven flow of a gas in a channel. The manner in which TMAC depends on the molecular mass is of importance as it influences the extent to which gas flow rates are affected by their mass, but there are conflicting opinions in the literature concerning the extent and even the sign of this dependence. We simulate the flow of the noble gases He, Ne, Ar, Kr, and Xe using molecular dynamics with Lennard-Jones potentials. The interaction with the wall is made realistic by simulating five layers of mobile atoms and allowing for adsorbed gas on the wall. With increasing mass of the gas, the TMAC exhibits asymptotic behaviour in approaching the value assumed to apply for an entrapped atom. Either increasing or decreasing TMAC with respect to an increasing molecular mass is produced, depending on the assumed TMAC of an entrapped atom. This resolves a conflict in the literature, where both increasing and decreasing trends are observed with mass.
Direct current reactive sputtering Cr–Cr2O3 cermet solar selective surfaces for solar hot water applications
Publisher: Elsevier BV
Date: 2009
Combined deposition and implantation in the cathodic arc for thick film preparation
Publisher: Elsevier BV
Date: 02-2001
Functional attachment of horse radish peroxidase to plasma-treated surfaces
Publisher: SPIE
Date: 16-02-2004
DOI: 10.1117/12.582373
Applications of the near-edge and low-loss fine structure in the analysis of diamond
Publisher: Elsevier BV
Date: 04-1989
Signal versus noise in fiber-coupled radiation dosimeters for medical applications
Publisher: SPIE
Date: 10-06-2004
DOI: 10.1117/12.540735
Combined influences of mechanical properties and surface roughness on the tribological properties of amorphous carbon coatings
Publisher: Elsevier BV
Date: 2006
Control of defects in optical fibers-a study using cathodoluminescence spectroscopy
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 1993
DOI: 10.1109/50.251176
New technology for PACVD
Publisher: Elsevier BV
Date: 08-1996
Hydrogen-free amorphous carbon preparation and properties
Publisher: Elsevier BV
Date: 04-1994
Effect of intrinsic stress on preferred orientation in AlN thin films
Publisher: AIP Publishing
Date: 30-01-2004
DOI: 10.1063/1.1640462
Abstract: We examine the effect of ion impact energy on the intrinsic stress and microstructure of aluminum nitride thin films deposited using a filtered cathodic arc. The dependence of intrinsic stress on ion impact energy is studied over the range from 0 to 350 V using dc bias and up to several kV for a fraction of the ions using pulse bias. For dc bias, the stress reaches a maximum at 200 V and decreases with further increase in ion bias. The preferred orientation of the crystallites was studied by cross-section transmission electron microscopy and diffraction. We found that there is a preference for the c crystallographic axis to lie in the plane of the film under high intrinsic stress conditions (4 GPa), whereas a c-axis orientation perpendicular to the plane of the film was observed for low intrinsic stress (0.25 GPa). We carried out calculations of the expected distribution of intensity in cross-sectional electron diffraction patterns to predict the effect of rotation freedom of crystallites with the c axis pinned. The calculated patterns agreed well with experiment.
Structure and hardness of diamond-like carbon films prepared by arc evaporation
Publisher: Springer Science and Business Media LLC
Date: 04-1988
DOI: 10.1007/BF01730760
Chemical toughening of glass by potassium diffusion: How non-bridging oxygen and a surface calcium barrier limit the process
Publisher: No publisher found
Date: 2019
Cluster of differentiation antibody microarrays on plasma immersion ion implanted polycarbonate
Publisher: Elsevier BV
Date: 02-2014
DOI: 10.1016/J.MSEC.2013.11.034
Abstract: Plasma immersion ion implantation (PIII) modifies the surface properties of polymers, enabling them to covalently immobilize proteins without using linker chemistry. We describe the use of PIII treated polycarbonate (PC) slides as a novel platform for producing microarrays of cluster of differentiation (CD) antibodies. We compare their performance to identical antibody microarrays printed on nitrocellulose-coated glass slides that are currently the industry standard. Populations of leukocytes are applied to the CD microarrays and unbound cells are removed revealing patterns of differentially immobilized cells that are detected in a simple label-free approach by scanning the slides with visible light. Intra-slide and inter-slide reproducibility, densities of bound cells, and limits of detection were determined. Compared to the nitrocellulose-coated glass slides, PIII treated PC slides have a lower background noise, better sensitivity, and comparable or better reproducibility. They require three-fold lower antibody concentrations to yield equivalent signal strength, resulting in significant reductions in production cost. The improved transparency of PIII treated PC in the near-UV and visible wavelengths combined with superior immobilization of biomolecules makes them an attractive platform for a wide range of microarray applications.
A centre-triggered magnesium fuelled cathodic arc thruster uses sublimation to deliver a record high specific impulse
Publisher: AIP Publishing
Date: 29-08-2016
DOI: 10.1063/1.4962124
Abstract: The cathodic arc is a high current, low voltage discharge that operates in vacuum and provides a stream of highly ionised plasma from a solid conducting cathode. The high ion velocities, together with the high ionisation fraction and the quasineutrality of the exhaust stream, make the cathodic arc an attractive plasma source for spacecraft propulsion applications. The specific impulse of the cathodic arc thruster is substantially increased when the emission of neutral species is reduced. Here, we demonstrate a reduction of neutral emission by exploiting sublimation in cathode spots and enhanced ionisation of the plasma in short, high-current pulses. This, combined with the enhanced directionality due to the efficient erosion profiles created by centre-triggering, substantially increases the specific impulse. We present experimentally measured specific impulses and jet power efficiencies for titanium and magnesium fuels. Our Mg fuelled source provides the highest reported specific impulse for a gridless ion thruster and is competitive with all flight rated ion thrusters. We present a model based on cathode sublimation and melting at the cathodic arc spot explaining the outstanding performance of the Mg fuelled source. A further significant advantage of an Mg-fuelled thruster is the abundance of Mg in asteroidal material and in space junk, providing an opportunity for utilising these resources in space.
Acetylene plasma coated surfaces for covalent immobilization of proteins
Publisher: Elsevier BV
Date: 07-2009
Reaction paths of phosphine dissociation on silicon (001)
Publisher: AIP Publishing
Date: 07-01-2016
DOI: 10.1063/1.4939124
Abstract: Using density functional theory and guided by extensive scanning tunneling microscopy (STM) image data, we formulate a detailed mechanism for the dissociation of phosphine (PH3) molecules on the Si(001) surface at room temperature. We distinguish between a main sequence of dissociation that involves PH2+H, PH+2H, and P+3H as observable intermediates, and a secondary sequence that gives rise to PH+H, P+2H, and isolated phosphorus adatoms. The latter sequence arises because PH2 fragments are surprisingly mobile on Si(001) and can diffuse away from the third hydrogen atom that makes up the PH3 stoichiometry. Our calculated activation energies describe the competition between diffusion and dissociation pathways and hence provide a comprehensive model for the numerous adsorbate species observed in STM experiments.
van der Pauw method for measuring resistivity of a plane sample with distant boundaries
Publisher: AIP Publishing
Date: 07-2009
DOI: 10.1063/1.3183503
Abstract: In the paper, we derive an algorithm which follows from the original van der Pauw’s technique for measuring resistivity with the added advantage of allowing contacts to be positioned a distance away from the boundary. For a large s le area, we show that the resistivity calculated by our algorithm is equivalent to the resistivity calculated by the original van der Pauw’s method. In practice, this configuration is easier to achieve and can eliminate errors associated with contacts that are not placed exactly at the edge.
Neuromorphic sensing of biomolecules covalently immobilised on polydimethyl glutarimide
Publisher: Elsevier BV
Date: 10-2023
Surface structure and sputtering in amorphous carbon thin films: a tight-binding study of film deposition
Publisher: IOP Publishing
Date: 18-01-2002
Nonequilibrium Route to Nanodiamond with Astrophysical Implications
Publisher: American Physical Society (APS)
Date: 17-02-2012
Optical properties of dense regular cermets with relevance to selective solar absorbers
Publisher: Elsevier BV
Date: 03-1979
¿erenkov Radiation in Optical Fiber Communication
Publisher: IEEE
Date: 03-2007
Plasma immersion ion implantation of a two-phase blend of polysulfone and polyvinylpyrrolidone
Publisher: Elsevier BV
Date: 05-2016
A self‐checking fiber optic dosimeter for monitoring common errors in brachytherapy applications
Publisher: Wiley
Date: 09-06-2009
DOI: 10.1118/1.3132406
Abstract: Scintillation dosimetry with optical fiber readout [fiber optic dosimetry (FOD)] requires accurate measurement of light intensity. It is therefore vulnerable to loss of calibration if any changes occur in the efficiency of the optical pathway between the scintillator and the light detector. The authors show in this article that common types of errors that arise during clinical use for brachytherapy applications can be quantified using a light emitting diode to stimulate the scintillator, the so-called LED-FOD method, in an integrated and easy-to-use control unit that incorporates a compact peripheral component interconnect extension for instrumentation. Common sources of error include bending and mechanical compression of the fiber optic components and changes in the temperature of the scintillator. The authors show that the method can detect all the common errors studied in this work and that different types of errors can result in different correlations between the LED stimulated signal and the brachytherapy source signal. For a single-type error the LED-FOD can be used easily for system diagnosis and validation with the possibility to correct the dosimeter reading if the correlation between the LED stimulated signal and the brachytherapy source signal can be defined. For more complex errors, resulting from two or more errors occurring simultaneously, the LED-FOD method can also allow the clinician to make a judgment on the reliability of the dosimeter reading. This self-checking method can enhance the clinical robustness of the FOD for achieving accurate dose control.
Optical constants and microstructure of stainless steel-carbon films prepared by reactive magnetron sputtering
Publisher: Elsevier BV
Date: 05-1982
A comparison of the strength of autohesion of plasma treated amorphous and semi‐crystalline PEEK films
Publisher: Wiley
Date: 23-11-2011
DOI: 10.1002/PAT.1791
Effect of sputtering-gas pressure on properties of silicon nitride films produced by helicon plasma sputtering
Publisher: Elsevier BV
Date: 03-2001
Atomic layer deposition of Al2O3 and Al2O3/TiO2 barrier coatings to reduce the water vapour permeability of polyetheretherketone
Publisher: Elsevier BV
Date: 09-2015
Electrodeless plasma thrusters for spacecraft: a review
Publisher: IOP Publishing
Date: 20-06-2017
Tropoelastin Switch and Modulated Endothelial Cell Binding to PTFE
Publisher: Springer Science and Business Media LLC
Date: 27-10-2011
Tetrahedral amorphous carbon properties and applications
Publisher: Elsevier BV
Date: 12-1993
Can small field diode correction factors be applied universally?
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.RADONC.2014.08.009
Abstract: Diode detectors are commonly used in dosimetry, but have been reported to over-respond in small fields. Diode correction factors have been reported in the literature. The purpose of this study is to determine whether correction factors for a given diode type can be universally applied over a range of irradiation conditions including beams of different qualities. A mathematical relation of diode over-response as a function of the field size was developed using previously published experimental data in which diodes were compared to an air core scintillation dosimeter. Correction factors calculated from the mathematical relation were then compared those available in the literature. The mathematical relation established between diode over-response and the field size was found to predict the measured diode correction factors for fields between 5 and 30 mm in width. The average deviation between measured and predicted over-response was 0.32% for IBA SFD and PTW Type E diodes. Diode over-response was found to be not strongly dependent on the type of linac, the method of collimation or the measurement depth. The mathematical relation was found to agree with published diode correction factors derived from Monte Carlo simulations and measurements, indicating that correction factors are robust in their transportability between different radiation beams.
Influence of dc bias voltage on the refractive index and stress of carbon-diamond films deposited from a CH4/Ar rf plasma
Publisher: AIP Publishing
Date: 15-11-1991
DOI: 10.1063/1.350219
Abstract: The dc self bias voltage developed during CH4/Ar radio frequency plasma-enhanced vapor deposition of thin films containing polycrystalline diamond grains within an a:C matrix (carbon-diamond) is found to influence the optical and mechanical properties of the films. In particular it is shown that there is a simultaneous etch deposition process which takes place, and that the dc bias can be used to control this etch rate, and hence the net film growth rate. When a balance between etching and deposition is achieved, the films show increased residual stress and optical density with exposure to Ar+ bombardment in the plasma. In addition to the measured dc bias the local electric field developed around the substrate is also found to significantly influence the energy with which ions impinge upon the growing film.
Exact modelling of cubic lattice permittivity and conductivity
Publisher: Springer Science and Business Media LLC
Date: 1977
DOI: 10.1038/265128A0
Mechanisms for Covalent Immobilization of Horseradish Peroxidase on Ion-Beam-Treated Polyethylene
Publisher: Hindawi Limited
Date: 2012
DOI: 10.6064/2012/126170
Abstract: The surface of polyethylene was modified by plasma immersion ion implantation. Structure changes including carbonization and oxidation were observed. High surface energy of the modified polyethylene was attributed to the presence of free radicals on the surface. The surface energy decay with storage time after treatment was explained by a decay of the free radical concentration while the concentration of oxygen-containing groups increased with storage time. Horseradish peroxidase was covalently attached onto the modified surface by the reaction with free radicals. Appropriate blocking agents can block this reaction. All aminoacid residues can take part in the covalent attachment process, providing a universal mechanism of attachment for all proteins. The native conformation of attached protein is retained due to hydrophilic interactions in the interface region. The enzymatic activity of covalently attached protein remained high. The long-term activity of the modified layer to attach protein is explained by stabilisation of unpaired electrons in sp 2 carbon structures. A high concentration of free radicals can give multiple covalent bonds to the protein molecule and destroy the native conformation and with it the catalytic activity. The universal mechanism of protein attachment to free radicals could be extended to various methods of radiation damage of polymers.
On the measurement of dose in-air for small radiation fields: Choice of mini-phantom material
Publisher: IOP Publishing
Date: 26-02-2015
DOI: 10.1088/0031-9155/60/6/2391
Abstract: The purpose of this work was to determine the effect of choice of mini-phantom material on the measurement and calculation of in-air output factors (Sc) in small fields. Monte Carlo simulations in conjunction with a theoretical determination of Sc were used to validate previously reported measurements. Options for alternative mini-phantom materials were compared. A 6 MV beam from a Varian Novalis linear accelerator operating in stereotactic (SRS) mode was modelled. Phase-space data were used to determine the theoretical value of Sc. To validate previously reported Sc measurements the data were used to model the fibre-optic detector and brass mini-phantom. The impact of mini-phantom material was investigated by comparing the energy spectra of electrons entering the detector volume as a function of field size, and comparing the simulated Sc-measurement to the theoretical calculation. In order to determine factors leading to changes in Sc with field size, the origins of particles in the beam as incident on the mini-phantom were determined. Sc values derived from simulated measurements using a brass mini-phantom on a fibre-optic detector agreed with the measured Sc to within 0.7%. For simulation of measurement for all other mini-phantom materials, Sc values agreed with the theoretically calculated values to within 0.6%. The dominant processes responsible for a decrease in Sc with field size is occlusion of the focal and primary collimator contributions, while the secondary scatter, from the flattening filter and cone collimators, has minimal effect. The secondary electron spectrum is affected by the choice of mini-phantom material, but is almost independent of field size. For cone-collimated small fields in the Novalis beam (<30 mm), the decrease in Sc with field size is primarily due to collimation of the focal radiation beam and scatter from the primary collimator. A fibre optic detector with either a brass, gold or lead mini-phantom with at least d(max) equivalent height is suited to measure Sc for small SRS fields. The use of materials with higher electron hysical density can be used to reduce the size of the mini-phantom and reduce spatial averaging.
Oxygen incorporation in Ti2AlC thin films
Publisher: AIP Publishing
Date: 11-02-2008
DOI: 10.1063/1.2838456
Abstract: Thin films of Ti2AlC MAX phase have been deposited using a multiple cathode pulsed cathodic arc. Evidence for substantial oxygen incorporation in the MAX phase is presented, likely originating from residual gas present in the vacuum chamber during deposition. The characteristic MAX phase crystal structure is maintained, in agreement with ab initio calculations, supporting substitutional O in C lattice positions. On the basis of these results, we propose the existence of a MAX phase-like material with material properties tuned by the incorporation of oxygen. Additionally, possible unintentional O incorporation in previously reported MAX phase materials is suggested.
Publisher's Note: “The gray body approximation for radiative heat transfer in evacuated tube solar collectors: Effects of envelope infrared transparency” [J. Appl. Phys. 131, 125001 (2022)]
Publisher: AIP Publishing
Date: 11-05-2022
DOI: 10.1063/5.0097289
Depth profiles of hydrogen and oxygen in hydrogenated amorphous silicon thin films
Publisher: Elsevier BV
Date: 04-1986
Substrate orientation effects on the nucleation and growth of the Mn+1AXn phase Ti2AlC
Publisher: AIP Publishing
Date: 2011
DOI: 10.1063/1.3527960
Abstract: The Mn+1AXn (MAX) phases are ternary compounds comprising alternating layers of a transition metal carbide or nitride and a third “A-group” element. The effect of substrate orientation on the growth of Ti2AlC MAX phase films was investigated by studying pulsed cathodic arc deposited s les grown on sapphire cut along the (0001), (101¯0), and (11¯02) crystallographic planes. Characterization of these s les was by x-ray diffraction, atomic force microscopy, and cross-sectional transmission electron microscopy. On the (101¯0) substrate, tilted (101¯8) growth of Ti2AlC was found, such that the TiC octahedra of the MAX phase structure have the same orientation as a spontaneously formed epitaxial TiC sublayer, preserving the typical TiC–Ti2AlC epitaxial relationship and confirming the importance of this relationship in determining MAX phase film orientation. An additional component of Ti2AlC with tilted fiber texture was observed in this s le tilted fiber texture, or axiotaxy, has not previously been seen in MAX phase films.
Cerenkov light spectrum in an optical fiber exposed to a photon or electron radiation therapy beam
Publisher: Optica Publishing Group
Date: 10-06-2009
DOI: 10.1364/AO.48.003362
Abstract: A Cerenkov signal is generated when energetic charged particles enter the core of an optical fiber. The Cerenkov intensity can be large enough to interfere with signals transmitted through the fiber. We determine the spectrum of the Cerenkov background signal generated in a poly(methyl methacrylate) optical fiber exposed to photon and electron therapeutic beams from a linear accelerator. This spectral measurement is relevant to discrimination of the signal from the background, as in scintillation dosimetry using optical fiber readouts. We find that the spectrum is approximated by the theoretical curve after correction for the wavelength dependent attenuation of the fiber. The spectrum does not depend significantly on the angle between the radiation beam and the axis of the fiber optic but is dependent on the depth in water at which the fiber is exposed to the beam.
Impact of a composite metal-glass system; A study using high-speed imaging
Publisher: SPIE
Date: 28-11-2009
DOI: 10.1117/12.822476
Micro‐CT Analysis of Implanted Poly‐Ether‐Ether‐Ketone Scaffolds: Plasma Immersion Ion Implantation Increases Osteoconduction
Publisher: Wiley
Date: 18-01-2023
Abstract: Poly‐ether‐ether‐ketone (PEEK) is a biocompatible, high‐strength polymer with biomechanical properties similar to soft bone that has been proposed as an alternative to titanium for orthopedic implants. Herein, micro‐CT imaging of a 3D printed PEEK scaffold treated with plasma immersion ion implantation (PIII) to assess the degree of osteoconduction relative to an identical untreated structure, by implantation in the scapula of sheep, is performed. To overcome the lack of contrast between soft tissue and PEEK, a customized apparatus and alignment technique is designed and constructed. Principal component analysis is used to accurately locate the boundaries of the implant in the 3D dataset, with respect to reference coordinates. It is found that, within the interior volume of the scaffold, the PIII treated PEEK contains bone that is both more dense and in higher amounts than for untreated PEEK. The untreated PEEK shows more bone immediately outside the boundaries of the scaffold, indicating a lower affinity of the untreated scaffold for in‐diffusion of osteocytes and associated mineralization. The greater osteoconduction of the PIII treated scaffold is attributed to the improvement in hydrophilicity and the provision of protein covalent binding.
Abrupt Stress Induced Transformation in Amorphous Carbon Films with a Highly Conductive Transition Phase
Publisher: American Physical Society (APS)
Date: 28-04-2008
Biocompatibility of calcium and phosphorus doped diamond-like carbon thin films synthesized by plasma immersion ion implantation and deposition
Publisher: Elsevier BV
Date: 04-2006
Transmission of Čerenkov radiation in optical fibers
Publisher: Optica Publishing Group
Date: 17-04-2007
DOI: 10.1364/OL.32.001205
Abstract: Cerenkov radiation is generated as an unwanted background when optical fibers carrying signals pass through radiation fields. The angular dependence of the intensity of ? Cerenkov radiation transmitted in silica-core fibers was measured using 6 and 12 MeV electron beams from a Varian Clinic accelerator. These confirmed theoretical predictions that the angular variation of ? Cerenkov radiation transmitted along optical fibers depends only on the refractive index difference Dn between the core and the cladding, and that the peak intensity is proportional to the cube of the fiber core radius.
Doping and STM tip-induced changes to single dangling bonds on Si(001)
Publisher: Elsevier BV
Date: 09-2007
Multilayered carbon films for tribological applications
Publisher: Elsevier BV
Date: 02-2003
Small field in-air output factors: The role of miniphantom design and dosimeter type
Publisher: Wiley
Date: 24-01-2014
DOI: 10.1118/1.4861710
Abstract: The commissioning of treatment planning systems and beam modeling requires measured input parameters. The measurement of relative output in-air, Sc is particularly difficult for small fields. The purpose of this study was to investigate the influence of miniphantom design and detector selection on measured Sc values for small fields and to validate the measurements against Monte Carlo simulations. Measurements were performed using brass caps (with sidewalls) or tops (no sidewalls) of varying heights and widths. The performance of two unshielded diodes (60012 and SFD), EBT2 radiochromic film, and a fiber optic dosimeter (FOD) were compared for fields defined by MLCs (5-100 mm) and SRS cones (4-30 mm) on a Varian Novalis linear accelerator. Monte Carlo simulations were performed to theoretically predict Sc as measured by the FOD. For all detectors, Sc agreed to within 1% for fields larger than 10 mm and to within 2.3% for smaller fields. Monte Carlo simulation matched the FOD measurements for all size of cone defined fields to within 0.5%. Miniphantom design is the most important variable for reproducible and accurate measurements of the in-air output ratio, S(c), in small photon fields (less than 30 mm). Sidewalls are not required for fields ≤ 30 mm and tops are therefore preferred over the larger caps. Unlike output measurements in water, S(cp), the selection of detector type for Sc is not critical, provided the active dosimeter volume is small relative to the field size.
Magnetised and unmagnetized axisymmetric particle-in-cell simulations of ion energy distributions in cathodic vacuum arcs
Publisher: IOP Publishing
Date: 08-2022
Abstract: Cathodic arcs are electrical discharges consisting of a succession of discrete pulses of energetic plasma travelling from the surface of a cathode toward an anode. Currently, there are no vacuum arc simulations where spots are continuously generated with a set frequency, including the far-field plasma jet, with the inclusion of kinetic behaviour for both ions and electrons. The VSim 11 particle-in-cell software was used to simulate specific vacuum arcs as axisymmetric, electrostatic, and fully kinetic, from the initial generation of each cathode spot to the streaming plasma discharge at a far field, validating the predictions against experimental data. The models were configured to match the experimental arc gun of Zohrer et al and the Mevva V experiment with the cathode materials Al and Nb. The ion and electron velocity data were collected at the far edge of the simulation domain, analogous to a physical energy detector. The simulations successfully predicted the evolution of ion charge state energy distributions, showing peak unmagnetized ion energies that agree with prior experimental data, resulting in a mean error of 3% for Al and Nb. A peak in the electrostatic potential is observed above the cathode surface, supporting the potential hump theory as the cause of the higher-than-expected ion energies observed in cathodic arc discharges. Lower than expected relative energies between ion charge states are observed, matching prior experimental results, with this coupling of ion charge states attributed to non-stationary electrostatic wave–particle interactions, as the use of collisionless simulations rules out Coulombic ion friction. Magnetised simulations incorporated a statically powered short solenoid equivalent to the coil used in the Mevva V experiment to create a erging magnetic nozzle. The magnetised simulation results demonstrate an annular jet of magnetically confined plasma and indicate an increase in nonstationary electrostatic effects including wave–particle interactions.
The Neurodevelopmental Hypothesis of Schizophrenia Convergent Clues from Epidemiology and Neuropathology
Publisher: Elsevier BV
Date: 09-2012
Current and future perspectives on biomaterials for segmental mandibular defect repair
Publisher: Informa UK Limited
Date: 28-03-2023
Directed cell attachment by tropoelastin on masked plasma immersion ion implantation treated PTFE
Publisher: Elsevier BV
Date: 10-2011
DOI: 10.1016/J.BIOMATERIALS.2011.05.060
Abstract: The ability to generate cell patterns on polymer surfaces is critical for the detailed study of cellular biology, the fabrication of cell-based biosensors, cell separation techniques and for tissue engineering. In this study contact tape masking and steel shadow masks were used to exclude plasma immersion ion implantation (PIII) treatment from defined areas of polytetrafluoroethylene (PTFE) surfaces. This process enabled patterned covalent binding of the cell adhesive protein, tropoelastin, without employing chemical linking molecules. Tropoelastin coating rendered the untreated regions cell adhesive and the PIII-treated area non-adhesive, allowing very fine patterning of cell adhesion to PTFE surfaces. A blocking step, such as with BSA or PEG, was not required to prevent cell binding to the underlying PIII-treated regions as tropoelastin coating alone performed this blocking function. Although tropoelastin coated the entire PTFE surface, the cell binding C-terminus of tropoelastin was markedly less solvent exposed on the PIII-treated, hydrophilic regions. The differential exposure of the C-terminus correlated with the patterned distribution of tropoelastin-mediated cell adhesion. This new methodology specifically enables directed cell behavior on a polymer surface using a simple one-step treatment process, by modulating the adhesive activity of a single extracellular matrix protein.
Etching and structural changes in nitrogen plasma immersion ion implanted polystyrene films
Publisher: Elsevier BV
Date: 06-2006
Photoresponse characteristics of n-type tetrahedral amorphous carbon/p-type Si heterojunction diodes
Publisher: AIP Publishing
Date: 25-04-1994
DOI: 10.1063/1.111649
Abstract: The photovoltaic behavior and spectral response of n-type (nitrogen-doped) tetrahedral amorphous carbon (ta-C) -type crystalline silicon heterojunction photodiodes are reported. Abrupt step junction type characteristics are observed with ta-C films ranging in thickness from 40 to 160 nm. The photovoltage increases and the prominent peak in responsivity shifts from 800 nm to longer wavelengths of 1000 nm as the doping in the ta-C films is increased, indicative of a widening of the depletion region in the Si. Use of the responsivity vs wavelength data with the Donnelly and Milnes model for an abrupt heterojunction is successful in predicting the depletion width in the Si and the doping level in the higher doped ta-C. The latter value coupled with the x-ray photoemission spectroscopy derived N concentration in the ta-C films enables an estimation of the doping efficiency. Secondary ion mass spectroscopy studies also confirm the abrupt nature of the junctions.
Optimizing the triggering mode for stable operation of a pulsed cathodic arc deposition system
Publisher: IOP Publishing
Date: 12-08-2003
Optical properties of chemically ordered a-Si1−xCx:H alloys
Publisher: AIP Publishing
Date: 15-02-1989
DOI: 10.1063/1.342940
Abstract: The optical properties (n,k,ε,neff) of chemically ordered a-Si1−xCx:H alloys have been measured and then analyzed with the effective-medium theory. Included is the first experimental result for an amorphous binary semiconductor that is known to be almost fully chemically ordered, and represented by the formula a-SiC0.64:H. Chemical order is induced by heavy dilution of the plasma with hydrogen. Chemical ordering shifts absorption to shorter wavelengths. Analysis using a scaling theory to define optical constants of different tetrahedron components leads to serious errors in the a-Si1−xCx:H series.
Accuracy of optical data derived from electron energy loss spectra by kramers-krönig analysis
Publisher: Elsevier BV
Date: 1987
Effect of scatter material on diode detector performance forin vivodosimetry
Publisher: IOP Publishing
Date: 13-12-2007
DOI: 10.1088/0031-9155/53/1/006
Abstract: The accuracy of Scanditronix EDE, EDP10 and EDP20 diodes for entrance dosimetry of complex fields has been assessed using static and dynamic multileaf collimator test fields on phantoms. Specifically, surrounding scatter material size and composition have been investigated. The EDP10 and EDP20 diodes incorporate steel build-up caps. The effect of varying the diameter of the wax scatter discs on the dosimeter response showed a systematic detector under-response for the smaller discs with errors up to 4.1% relative to full scatter conditions. In static fields, all diodes over-respond at a field size of 1 x 1 cm(2). Diodes with non-water-equivalent build-up material exhibit over-response of up to 10.8%. In dynamic fields, diodes over-respond when there is an increased contribution from phantom scatter and under-respond in shielded regions due to low dose rate and beam hardening. For high dose regions, all diodes over-respond with the greatest over-response of 3.8% observed with a 6 mm sliding window field. The EDE diode with a 6 cm scatter disc correlated best with the reference dosimeter. A diode design with minimal non-water-equivalent components and the addition of a 6 cm diameter water-equivalent disc for scatter material is recommended for the in vivo dosimetry of 6 MV complex fields.
Pathways for thermal phosphorus desorption from the silicon (001) surface
Publisher: American Physical Society (APS)
Date: 10-12-2010
Simulation of a semitransparent conducting mesh electrode for plasma immersion ion implantation
Publisher: AIP Publishing
Date: 09-2005
DOI: 10.1063/1.2039527
Abstract: Particle-in-cell simulations of plasma evolution in the vicinity of a mesh electrode that is semitransparent to ions are presented. Space-charge accumulation and ion focusing have an important effect on the ion trajectories and ion energy distribution inside the mesh. The results indicate that when such an electrode is used to assist plasma immersion ion implantation of insulating targets, the initial plasma conditions and mesh geometry are key factors in achieving optimum dose uniformity and implanted ion energy.
The time-dependent development of electric double-layers in pure water at metal electrodes: the effect of an applied voltage on the local pH
Publisher: The Royal Society
Date: 10-08-2011
Abstract: Water maintains a pH value of 7 owing to a balance between dissociation into hydronium (H 3 O + ) and hydroxide (OH − ) ions and their recombination. An examination is made of the effect of applying voltages from 0.1 to 0.82 V on these ions between metal electrodes which act as blocking electrodes. The movement of hydronium ions away from and hydroxide ions towards the anode is followed. This movement results in the formation of an ion double-layer with a steeply rising electric field and a maximum pH of approximately 12. At the cathode, the opposite occurs and the pH reaches a minimum of approximately 1.7. The time constant for double-layer formation is found to increase exponentially with voltage, and the pH at each electrode varies linearly with voltage thus, the pH can be controlled systematically at each electrode. The dimensions of the double-layers are such that large biomolecules at the electrodes will be immersed in a pH environment close to the extreme values at the electrode. This means that the charge on the molecules may be controlled as they adsorb onto the electrode this may prove valuable for the operation of biosensors.
A plastic scintillation dosimeter for high dose rate brachytherapy
Publisher: IOP Publishing
Date: 09-10-2006
DOI: 10.1088/0031-9155/51/21/008
Abstract: In vivo dose verification in brachytherapy requires a small insertable dosimeter with a real-time readout capability. Fibre optic scintillation dosimeters, consisting of a plastic scintillator coupled to an optical fibre, are one of the most promising dosimeters for this application. We have developed two sizes of the BrachyFOD scintillation dosimeter which have external diameters of 2.2 mm and 1 mm and have determined their important dosimetric characteristics (depth dose relation, angular dependence, temperature dependence, energy dependence). We have shown that the background signal created by Cerenkov and fibre fluorescence does not significantly affect the performance in most clinical geometries using an (192)Ir source from an HDR brachytherapy unit. The dosimeter design enables readout at less than 0.5 s intervals. The BrachyFOD satisfies the need for a real-time in vivo brachytherapy dosimeter.
Enhancement of microarcing at a grounded chamber wall by nonvanishing ion sheath in a radio-frequency capacitive discharged plasma
Publisher: AIP Publishing
Date: 27-10-2005
DOI: 10.1063/1.2126126
Abstract: One-dimensional hybrid particle-in-cell simulations in cylindrical r coordinate, with particle ions and Boltzmann’s distribution of electrons, are used to investigate the arcing effect in radio-frequency (rf) capacitively coupled discharged plasma. The simulation shows that the arcing at the chamber wall is enhanced by the nonvanishing ion sheath at the surface, such that the emission electrons current will last for several tens of rf cycles. On the other hand, at the inner electrode, the electron emission occurs only during certain phases of the rf cycle and does not promote arc growth.
Preferred orientation in carbon films induced by energetic condensation
Publisher: Elsevier BV
Date: 12-1996
A general approach to generate random variates for multivariate copulae
Publisher: Wiley
Date: 03-2018
DOI: 10.1111/ANZS.12209
Raman spectroscopy study of DLC films prepared by RF plasma and filtered cathodic arc
Publisher: Elsevier BV
Date: 04-2007
Co-deposition of band-gap tuned Zn1−xMgxO using high impulse power- and dc-magnetron sputtering
Publisher: IOP Publishing
Date: 11-03-2015
Electron optical techniques for microstructural andcompositional analysis of thin films
Publisher: Elsevier BV
Date: 1990
Benzene and Pyridine on Silicon (001): A Trial Ground for Long-Range Corrections in Density Functional Theory
Publisher: American Chemical Society (ACS)
Date: 05-05-2017
Single P and As dopants in the Si(001) surface
Publisher: AIP Publishing
Date: 13-11-2007
DOI: 10.1063/1.2786991
Abstract: Using first-principles density functional theory, we discuss doping of the Si(001) surface by a single substitutional phosphorus or arsenic atom. We show that there are two competing atomic structures for isolated Si–P and Si–As heterodimers, and that the donor electron is delocalized over the surface. We also show that the Si atom dangling bond of one of these heterodimer structures can be progressively charged by additional electrons. It is predicted that surface charge accumulation as a result of tip-induced band bending leads to structural and electronic changes of the Si–P and Si–As heterodimers which could be observed experimentally. Scanning tunneling microscopy (STM) measurements of the Si–P heterodimer on a n-type Si(001) surface reveal structural characteristics and a bias-voltage dependent appearance, consistent with these predictions. STM measurements for the As:Si(001) system are predicted to exhibit similar behavior to P:Si(001).
Tetrahedral bonding in amorphous carbon
Publisher: IOP Publishing
Date: 12-1996
Neutron and Raman study of the lattice dynamics of deuterated thiourea
Publisher: IOP Publishing
Date: 07-07-1975
Dielectric properties and ferroelectric transitions of thiourea
Publisher: IOP Publishing
Date: 28-02-1973
Memristor and selector devices fabricated from HfO2−xNx
Publisher: AIP Publishing
Date: 04-04-2016
DOI: 10.1063/1.4945727
Abstract: Monoclinic HfO2−xNx has been incorporated into two-terminal devices exhibiting either memristor or selector operation depending on the controlled inclusion/suppression of mobile oxygen vacancies. In HfO2 memristors containing oxygen vacancies, gradual conductance modulation, short-term plasticity, and long-term potentiation were observed using appropriate voltage-spike stimulation, suggesting suitability for artificial neural networks. Passivation of oxygen vacancies, confirmed by X-ray absorption spectroscopy, was achieved in HfO2−xNx films by the addition of nitrogen during growth. Selector devices formed on these films exhibited threshold switching and current controlled negative differential resistance consistent with thermally driven insulator to metal transitions.
Cracking of titanium nitride films grown on polycarbonate
Publisher: Elsevier BV
Date: 02-2007
Radiation responses of cancer and normal cells to split dose fractions with uniform and grid fields: increasing the therapeutic ratio.
Publisher: Informa UK Limited
Date: 24-03-2022
DOI: 10.1080/09553002.2022.2047826
Abstract: Radiation treatment of cancer is usually delivered in a prescribed sequence of dose fractions within which the dependence of dose on time is determined by the treatment plan. New techniques, such as stereotactic body radiation therapy (SBRT) and image guided radiation therapy (IGRT) have been introduced with the motivation of improving therapeutic outcomes, with the consequence that the time dependence of the dose within a fraction is modified. Here, we test whether an increased toxicity to cancer cells arises when a radiation treatment fraction is delivered in two equal parts, allowing time for the expression of factors, for ex le, RONS and cytokines, in response to the first dose which may sensitize cells to the second dose. A medium time delay between 15 and 60 minutes is proposed to allow factors to be expressed before repair takes place. A grid field is used to enhance diffusion of the factors. The cell lines used in the study were two prostate cancers (LNCaP and DU 145), a normal prostate (PNT1A), a non-small cell lung cancer (NCI-H460), and a glioma (Hs 683). Uniform or spatially modulated grid fields, delivering the same mean dose, were used. The results for the clonogenic survival fractions were grouped into a 'short' delay (under 10 minutes) and a 'medium' delay (between 15 and 60 minutes). The medium delay with a grid field yielded a significant increase in toxicity for the four cancer cell lines. The medium delay with a uniform field gave a significant increase in toxicity for the two prostate cancer cell lines. A highly significant increase was found in the therapeutic ratio, defined as the ratio of the survival of prostate normal to prostate cancer cells. The findings show that the intra-fractional dose schedule with medium time delay offers an opportunity to increase the toxicity of radiation to cancer cells, relative to a single radiation delivery. For all cancer cell lines, a grid field gives a greater toxic effect than a uniform field. The split dose treatment offers an increase in cancer toxicity while preserving normal cells, improving the outcomes of a treatment.
Correlation between film structures and potential limits for hydrogen and oxygen evolutions at a-C:N film electrochemical electrodes
Publisher: Elsevier BV
Date: 04-2008
The effect of argon on the structure of amorphous SiBCN materials: an experimental andab initiostudy
Publisher: IOP Publishing
Date: 03-02-2006
Quantification of dose in plasma immersion ion implantation of polymer bone scaffolds: Probe diagnostics of a pulsed dielectric barrier discharge
Publisher: Wiley
Date: 16-08-2020
Plasma modified surfaces for covalent immobilization of functional biomolecules in the absence of chemical linkers: towards better biosensors and a new generation of medical implants
Publisher: Springer Science and Business Media LLC
Date: 23-02-2010
Lattice dynamics of urea
Publisher: IOP Publishing
Date: 28-10-1971
Bonding in a-Si1−xCx: H films studied by electron energy loss near edge structure
Publisher: Elsevier BV
Date: 08-1986
Dose mapping of the rectal wall during brachytherapy with an array of scintillation dosimeters
Publisher: Wiley
Date: 28-04-2010
DOI: 10.1118/1.3397446
Abstract: In pelvic brachytherapy treatments, the rectum is an organ at risk. The authors have developed an array of scintillation dosimeters suitable for in vivo use that enables quality assurance of the treatment delivery and provides an alert to potential radiation accidents. Ultimately, this will provide evidence to direct treatment planning and dose escalation and correlate dose with the rectal response. An array of 16 scintillation dosimeters in an insertable applicator has been developed. The dosimeters were calibrated simultaneously in a custom designed circular jig before use. Each dosimeter is optically interfaced to a set of pixels on a CCD camera located outside the treatment bunker. A customized software converts pixel values into dose rate and accumulates dose for presentation during treatment delivery. The performance of the array is tested by simulating brachytherapy treatments in a water phantom. The treatment plans were designed to deliver a known dose distribution on the surface of the rectal applicator, assumed to represent the dose to the rectal wall. The measured doses were compared to those predicted by the treatment plan and found to be in agreement to within the uncertainty in measurement, usually within 3%. The array was also used to track the progression of the source as it moved along the catheter. The measured position was found to agree with the position reported by the afterloader to within the measurement uncertainty, usually within 2 mm. This array is capable of measuring the actual dose received by each region of the rectal wall during brachytherapy treatments. It will provide real time monitoring of treatment delivery and raise an alert to a potential radiation accident. Real time dose mapping in the clinical environment will give the clinician additional confidence to carry out dose escalation to the tumor volume while avoiding rectal side effects.
All particle simulations of cathodic arc plasmas
Publisher: AIP Publishing
Date: 05-2006
DOI: 10.1063/1.2197032
Abstract: The early stages of the expansion of fully ionized cathode spot cathodic arc plasmas from a localized initial volume are simulated by an all particle molecular dynamics model. The particles are given an initial temperature and interact by Coulomb forces. Although there are limits on the number of particles and the starting density, the model is relevant in describing processes occurring in cells that are the smallest structures of a cathodic arc. Our model predicts that a cell undergoes an explosive expansion leading to a halo of electrons surrounding an ion-rich core. The ion kinetic energies are lower than experimental observation but may be consistent with them after extrapolation to higher initial densities. For mixed charge state plasmas, the ion kinetic energy increases with ion charge state.
Real-time verification of HDR brachytherapy source location: implementation of detector redundancy
Publisher: IOP Publishing
Date: 07-01-2005
DOI: 10.1088/0031-9155/50/2/010
Abstract: Independent treatment verification for high dose rate (HDR) brachytherapy is needed to ensure that the treatment proceeds as prescribed. In this paper, we investigate the feasibility of a proposed real-time source position verification process. This process provides immediate confirmation of the source position during the treatment, so that the treatment can be aborted and modified if necessary. We show that an array of dosimeters placed on the patient's skin can independently verify the position in three dimensions. This verification was demonstrated by using a diamond detector placed in several locations on the surface of an anthropomorphic phantom. A mathematical algorithm was constructed to estimate the location of the source given a measured data set in the presence of tissue heterogeneity. The accuracy of the source localization was found to increase with the number of detectors used to compute the estimation of the source position. The resolution to which the 12 detectors can identify the location of the source was within 3 mm.
Electron tomography and computer visualisation of a three-dimensional ‘photonic’ crystal in a butterfly wing-scale
Publisher: Elsevier BV
Date: 2002
DOI: 10.1016/S0968-4328(01)00044-0
Abstract: A combination of transmission electron tomography and computer modelling has been used to determine the three-dimensional structure of the photonic crystals found in the wing-scales of the Kaiser-I-Hind butterfly (Teinopalpus imperialis). These scales presented challenges for electron microscopy because the periodicity of the structure was comparable to the thickness of a section and because of the complex connectivity of the object. The structure obtained has been confirmed by taking slices of the three-dimensional computer model constructed from the tomography and comparing these with transmission electron microscope (TEM) images of microtomed sections of the actual scale. The crystal was found to have chiral tetrahedral repeating units packed in a triclinic lattice.
Carbon films deposited by mixed-mode high power impulse magnetron sputtering for high wear resistance: The role of argon incorporation
Publisher: Elsevier BV
Date: 10-2019
Plasma immersion ion‐implanted 3D‐printed PEEK bone implants: In vivo sheep study shows strong osseointegration
Publisher: Wiley
Date: 23-02-2022
Abstract: Adhesion of regenerating bone tissue to orthopaedic implants is critical to their long‐term success. Titanium has excess rigidity, interferes with imaging, and complicates radiation treatment. Poly(ether‐ether‐ketone) (PEEK) is a preferred material, but is limited by biological inertness. We show that plasma immersion ion implantation (PIII) imparts osteoadhesion on 3D printed PEEK using in vitro pull‐off tests and in vivo torque tests in a sheep scapula model. PIII‐PEEK prints incubated with bone cells in vitro show 9–14 times higher pull‐off strength, compared to untreated implants. Treated implants in vivo require seven times higher torque for release from the sheep scapula. We propose PIII‐PEEK as a scaffold material with tensile properties analogous to collagen, the fibrillar component of bone, to produce fracture‐tough fully integrating scaffolds.
Optical properties of plasma‐treated PEEK: Monitoring colour and crystallinity for applications in medicine and dentistry using ellipsometry
Publisher: Wiley
Date: 10-02-2022
Abstract: Poly‐ether‐ether‐ketone (PEEK) is a widely used and versatile polymer. Here, we use ellipsometry to determine the wavelength‐dependent optical properties of PEEK before and after the surface is modified by plasma immersion ion implantation (PIII), a technique that renders the surface hydrophilic and bio‐active. Lorentz and Gaussian oscillator models are used to fit the data for extraction of the optical constants and the dielectric function. The effect of PIII, even for short treatment times, changes the optical properties of PEEK, indicative of an amorphisation of the initial semicrystalline structure that broadens the electronic density of states distribution. The progressive changes in the optical properties with treatment time allow assessment of colour changes and estimation of ion dose in the PIII process.
Increasing binding density of yeast cells by control of surface charge with allylamine grafting to ion modified polymer surfaces
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.COLSURFB.2014.07.026
Abstract: Plasma immersion ion implantation (PIII) treatment of polymers creates a biointerface capable of direct covalent immobilization of biomolecules. The immobilization of protein molecules is achieved by covalent bonds formed between embedded radicals on the treated surface and amino acid side chains and cells can be immobilized through cell-wall proteins. The attachment density of negatively charged entities on a PIII treated surface is inhibited by its negative surface charge at neutral pH. To reduce the negative charge of PIII treated surfaces in phosphate buffer (pH 7.4, 11mM), we develop an effective approach of grafting allylamine monomers onto the treated surface. The results reveal reactions between allylamine and radicals on the PIII treated surface. One of these triggers polymerization, increasing the number of amine groups grafted. As a consequence, the PIII treated polystyrene surface after allylamine exposure becomes more hydrophobic and less negatively charged in phosphate buffer. Using yeast cells as an ex le, we have shown a significant improvement (6-15 times) of cell density immobilized on the PIII treated surface after exposure to allylamine.
Development of the nanotiter plate for use in antibody and cell array technologies
Publisher: SPIE
Date: 16-02-2005
DOI: 10.1117/12.582580
The angular dependence and effective point of measurement of a cylindrical scintillation dosimeter with and without a radio-opaque marker for brachytherapy
Publisher: IOP Publishing
Date: 17-03-2009
DOI: 10.1088/0031-9155/54/7/024
Abstract: Fibre optic scintillation dosimeters, consisting of a plastic scintillator coupled to an optical fibre, are a promising dosimeter in brachytherapy applications. The combination of tissue equivalence, real-time readout and small spatial size makes them especially attractive for in vivo verification of patient treatments. Given that the orientation of the dosimeter with respect to the radioactive source changes during brachytherapy treatment, the angular dependence of the dosimeter is important. We derived the dependence of the response of a cylindrical dosimeter to a point radiation source as a function of distance along its axis and along a radius. Using the results, the effective point of measurement of a cylindrical scintillator was located for two points in the angular response curve as a function of distance between the source and dosimeter. We measured the angular response experimentally for a cylindrical scintillation dosimeter, when the source was located at a distance of 50 mm from the centre of the scintillator. A refinement of the design, in which a radio-opaque marker is incorporated into the tip for accurate localization in the patient, modifies the angular response of the dosimeter. For this new dosimeter design, we show that the dosimeter response decreases by 20% when the source is located on the axis of the scintillator, due to absorption by the marker. The dosimeter response becomes almost angle independent at 10 degrees away from the axis. Excluding this cone, a cylindrical scintillation dosimeter which incorporates a radio-opaque marker was found to be angle independent to within 2%. In most clinical brachytherapy applications, this design has an acceptable angular dependence.
Adherent carbon film deposition by cathodic arc with implantation
Publisher: American Vacuum Society
Date: 03-1995
DOI: 10.1116/1.579372
Abstract: A method of improving the adhesion of carbon thin films deposited using a cathodic vacuum arc by the use of implantation at energies up to 20 keV is described. A detailed analysis of carbon films deposited onto silicon in this way is carried out using complementary techniques of transmission electron microscopy and x-ray photoelectron spectroscopy (XPS) is presented. This analysis shows that an amorphous mixing layer consisting of carbon and silicon is formed between the grown pure carbon film and the crystalline silicon substrate. In the mixing layer, it is shown that some chemical bonding occurs between carbon and silicon. Damage to the underlying crystalline silicon substrate is observed and believed to be caused by interstitial implanted carbon atoms which XPS shows are not bonded to the silicon. The effectiveness of this technique is confirmed by scratch testing and by analysis with scanning electron microscopy which shows failure of the silicon substrate occurs before delamination of the carbon film.
Properties of ZrN x prepared by ion-assisted deposition
Publisher: Springer Science and Business Media LLC
Date: 08-1990
DOI: 10.1007/BF00722192
Formation of theM A X
Publisher:
American Physical Society (APS)
Date:
15-09-2009
Publisher: American Physical Society (APS)
Date: 15-09-2009
Twisted pair of optic fibers for background removal in radiation fields
Publisher: The Optical Society
Date: 30-07-2013
DOI: 10.1364/AO.52.005500
In vivo biocompatibility of a plasma-activated, coronary stent coating
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.BIOMATERIALS.2012.07.059
Abstract: Bare metal and drug-eluting coronary stents suffer an inherent lack of vascular cell and blood compatibility resulting in adverse patient responses. We have developed a plasma-activated coating (PAC) for metallic coronary stents that is durable, withstands crimping and expansion, has low thrombogenicity and can covalently bind proteins, linker-free. This has been shown to enhance endothelial cell interactions in vitro and has the potential to promote biointegration of stents. Using the rabbit denuded iliac artery model, we show for the first time that PAC is a feasible coating for coronary stents in vivo. The coating integrity of PAC was maintained following implantation and expansion. The rate of endothelialization, strut coverage, neointimal response and the initial immune response were equivalent to bare metal stents. Furthermore, the initial thrombogenicity caused by the PAC stents showed a reduced trend compared to bare metal stents. This work demonstrates a robust, durable, non-cytotoxic plasma-based coating technology that has the ability to covalently immobilize bioactive molecules for surface modification of coronary stents. Improvements in the clinical performance of implantable cardiovascular devices could be achieved by the immobilization of proteins or peptides that trigger desirable cellular responses.
An mHealth intervention to improve nurses' atrial fibrillation and anticoagulation knowledge and practice: the EVICOAG study
Publisher: Oxford University Press (OUP)
Date: 08-2019
Abstract: There is a need to improve cardiovascular nurses’ knowledge and practices related to stroke prevention, atrial fibrillation and anticoagulation therapy. The aim of this study was to evaluate the efficacy of EVICOAG – a novel mHealth, smartphone-based, spaced-learning intervention on nurses’ knowledge of atrial fibrillation and anticoagulation. Nurses employed in four clinical specialties (neuroscience, stroke, rehabilitation, cardiology) across three hospitals were invited to participate. In this quasi-experimental study, 12 case-based atrial fibrillation and anticoagulation learning scenarios (hosted by an mHealth platform) were delivered to participants’ smartphones over a 6-week period (July–December 2016) using a spaced timing algorithm. Electronic surveys to assess awareness and knowledge were administered pre (T1) and post (T2) intervention. From 74 participants recruited to T1, 40 completed T2. There was a 54% mean improvement in knowledge levels post-intervention. The largest improvement was achieved in domains related to medication interaction and stroke and bleeding risk assessment. Post-intervention, those who completed T2 were significantly more likely to use CHA 2 DS 2 -VASc (2.5% vs. 37.5%) and HAS-BLED (2.5% vs. 35%) tools to assess stroke and bleeding risk, respectively ( P .01). The EVICOAG intervention improved nurses’ knowledge of atrial fibrillation and anticoagulation, and influenced their uptake and use of stroke and bleeding risk assessment tools in clinical practice. Future research should focus on whether a similar intervention might improve patient-centred outcomes such as patients’ knowledge of their condition and therapies, medication adherence, time in the therapeutic range and quality of life.
Scintillation dosimeter arrays using air core light guides: simulation and experiment
Publisher: IOP Publishing
Date: 26-05-2010
DOI: 10.1088/0031-9155/55/12/009
Abstract: The performance of a scintillation dosimeter that uses a silvered air core light guide is examined by Monte Carlo (MC) simulations and by experiment to determine its suitability for array dosimetry in external beam radiotherapy. The air core light guide avoids the generation of the Cerenkov background that is produced in a conventional optical fibre. MC simulations using a 6 MV photon beam showed that silver thicknesses of less than 1 microm compensated for the effects of the other material components, to give the dosimeter water equivalence within 0.5%. A second dosimeter located adjacent to the primary dosimeter in any direction affected the dose measurement by less than 1.5%, when the centre-to-centre spacing was 1.3 mm or greater. When the dosimeter array is located perpendicular to the beam central axis, with a spacing of 2.5 mm, the calculated deviation from the dose deposited in water was less than 2%. When the dosimeter array is located parallel to the beam central axis with a spacing of 10 mm, the calculated dose readings deviated from water by less than 2.5%. The simulation results were confirmed with experiment for two neighbouring dosimeters and a small densely packed array. No proximity effects were measured within the experimental error of +/-1.5%. These results confirm the dosimetric accuracy of the air core dosimeter design without the need for correction factors. The dosimeter has excellent potential for use in arrays.
Models for the bystander effect in gradient radiation fields: Range and signalling type
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.JTBI.2018.06.027
Abstract: Bystander responses to radiation are responsible for a significant fraction of cell death, but are not included in the conventional linear-quadratic (LQ) radiobiological model. Strong dose gradients in radiation fields affect the distribution of bystander signals and can be used to decrease the survival of cancer cells. Predictive models incorporating bystander effects are needed to design the dose gradients in modulated fields to improve cancer treatments. Fundamental questions concern the nature and range of bystander signalling. Some authors propose bystander signals are carried by diffusing molecular factors expressed into the extracellular medium and that strong dose gradients drive their diffusion. Others propose bystander effects occur between neighbouring cells through gap-junctions, leaving no universal agreement. Here we test three assumptions concerning the effective range of bystander signals using both average and local measures of survival. Model 1 assumes short range signalling (e.g. gap-junction mediated) proportional to the local dose gradient, without relying on diffusion across the extracellular medium Model 2 assumes metabolite diffusion governed by Fick's second law with either negative or both signs of bystander effect Model 3 assumes that the extent of signal production is dependent on the average of the dose gradient over the field and that the signals have long range distribution. A single bystander parameter for each model was fitted to observed average survival of cancer cells in uniform and modulated fields. All models gave better fits than the classical LQ model. Model 2 fitted best with one sign of bystander effect on survival. Model 3 gave the best overall fit of average survival. The models were then used to predict local survival and survival as a function of dose in modulated fields, using independent datasets, without changing the bystander parameter. Model 3 gave the best overall prediction. This study demonstrates that the bystander effect can be controlled by design of the radiation field modulation.
Effect of implanted argon on hardness of novel magnetron sputtered Si–B–C–N materials: experiments andab initiosimulations
Publisher: IOP Publishing
Date: 25-04-2007
Codoping of aluminum and gallium with nitrogen in ZnO: A comparative first-principles investigation
Publisher: American Physical Society (APS)
Date: 23-06-2009
Covalent immobilisation of tropoelastin on a plasma deposited interface for enhancement of endothelialisation on metal surfaces
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.BIOMATERIALS.2008.11.009
Abstract: Currently available endovascular metallic implants such as stents exhibit suboptimal biocompatibility in that they re-endothelialise poorly leaving them susceptible to thrombosis. To improve the interaction of these implants with endothelial cells we developed a surface coating technology, enabling the covalent attachment of biomolecules to previously inert metal surfaces. Using horseradish peroxidase as a probe, we demonstrate that the polymerised surface can retain the presentation and activity of an immobilised protein. We further demonstrated the attachment of tropoelastin, an extracellular matrix protein critical to the correct arrangement and function of vasculature. Not only it is structurally important, but it plays a major role in supporting endothelial cell growth, while modulating smooth muscle cell infiltration. Tropoelastin was shown to bind to the surface in a covalent monolayer, supplemented with additional physisorbed multilayers on extended incubation. The physisorbed tropoelastin layers can be washed away in buffer or SDS while the first layer of tropoelastin remains tightly bound. The plasma coated stainless steel surface with immobilised tropoelastin was subsequently found to have improved biocompatibility by promoting endothelial cell attachment and proliferation relative to uncoated stainless steel controls. Tropoelastin coatings applied to otherwise inert substrates using this technology could thus have broad applications to a range of non-polymeric vascular devices.
Optical fiber design and the trapping of Cerenkov radiation
Publisher: Optica Publishing Group
Date: 20-12-2006
DOI: 10.1364/AO.45.009151
Abstract: Cerenkov radiation is generated in optical fibers immersed in radiation fields and can interfere with signal transmission. We develop a theory for predicting the intensity of Cerenkov radiation generated within the core of a multimode optical fiber by using a ray optic approach and use it to make predictions of the intensity of radiation transmitted down the fiber in propagating modes. The intensity transmitted down the fiber is found to be dominated by bound rays with a contribution from tunneling rays. It is confirmed that for relativistic particles the intensity of the radiation that is transmitted along the fiber is a function of the angle between the particle beam and the fiber axis. The angle of peak intensity is found to be a function of the fiber refractive index difference as well as the core refractive index, with larger refractive index differences shifting the peak significantly toward lower angles. The angular range of the distribution is also significantly increased in both directions by increasing the fiber refractive index difference. The intensity of the radiation is found to be proportional to the cube of the fiber core radius in addition to its dependence on refractive index difference. As the particle energy is reduced into the nonrelativistic range the entire distribution is shifted toward lower angles. Recommendations on minimizing the quantity of Cerenkov light transmitted in the fiber optic system in a radiation field are given.
Characteristics of phosphorus-doped diamond-like carbon films synthesized by plasma immersion ion implantation and deposition (PIII and D)
Publisher: Elsevier BV
Date: 04-2007
Linker-free covalent attachment of the extracellular matrix protein tropoelastin to a polymer surface for directed cell spreading
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.ACTBIO.2009.05.016
Abstract: Polymers are used for the fabrication of many prosthetic implants. It is desirable for these polymers to promote biological function by promoting the adhesion, differentiation and viability of cells. Here we have used plasma immersion ion implantation (PIII) treatment of polystyrene to modify the polymer surface, and so modulate the binding of the extracellular matrix protein tropoelastin. PIII treated, but not untreated polystyrene, bound tropoelastin in a sodium dodecyl sulfate (SDS)-resistant manner, consistent with previous enzyme-binding data that demonstrated the capability of these surfaces to covalently attach proteins without employing chemical linking molecules. Furthermore sulfo-NHS acetate (SNA) blocking of tropoelastin lysine side chains eliminated the SDS-resistant binding of tropoelastin to PIII-treated polystyrene. This implies tropoelastin is covalently attached to the PIII-treated surface via its lysine side chains. Cell spreading was only observed on tropoelastin coated, PIII-treated polystyrene surfaces, indicating that tropoelastin was more biologically active on the PIII-treated surface compared to the untreated surface. A contact mask was used to pattern the PIII treatment. Following tropoelastin attachment, cells spread preferentially on the PIII-treated sections of the polystyrene surface. This demonstrates that PIII treatment of polystyrene improves the polymer's tropoelastin binding properties, with advantages for tissue engineering and prosthetic design.
Electrical conductivity as a measure of the continuity of titanium and vanadium thin films
Publisher: Elsevier BV
Date: 03-2005
Application of the heat equation to the calculation of temperature rises from pulsed microwave exposure
Publisher: Elsevier BV
Date: 06-2003
Production of solar absorbing cermet films by dual cathode d.c. magnetron sputtering
Publisher: Elsevier BV
Date: 10-1979
Amorphous and crystalline phases in thermal quench simulations of alumina
Publisher: AIP Publishing
Date: 27-04-2009
DOI: 10.1063/1.2739538
Abstract: The authors report molecular dynamics simulations of alumina (Al2O3) during crystallization from the melt. Using liquid quench methods, they investigate the effect of cooling rate on the structural evolution of the α, κ, and the bixbyite phases. A critical temperature window is identified, where the time spent in this window is crucial in determining the extent to which the systems approach crystallinity. A strong dependence is observed between the final structure and the quench rate, which is most pronounced for the α phase and to lesser extent for the other phases. The results show that the different phases have different tendencies to crystallize that are determined by energetics, complexity of crystal structure, and the number of metastable states.
Enhanced water vapour flow in silica microchannels and interdiffusive water vapour flow through anodic aluminium oxide (AAO) membranes
Publisher: SPIE
Date: 22-12-2015
DOI: 10.1117/12.2202469
The linker-free covalent attachment of collagen to plasma immersion ion implantation treated polytetrafluoroethylene and subsequent cell-binding activity
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.BIOMATERIALS.2009.12.009
Abstract: It is desirable that polymers used for the fabrication of prosthetic implants promote biological functions such as cellular adhesion, differentiation and viability. In this study, we have used plasma immersion ion implantation (PIII) to modify the surface of polytetrafluoroethylene (PTFE), thereby modulating the binding mechanism of collagen. The amount of collagen bound to the polymer surface following PIII-treatment was similar to that bound by non-covalent physisorption. In a manner consistent with previous enzyme and tropoelastin binding data, the collagen bound to the PIII-treated PTFE surface was resistant to sodium dodecyl sulfate (SDS) elution whilst collagen bound to the untreated surface was fully removed. This demonstrates the capability of PIII-treated surfaces to covalently attach collagen without employing chemical linking molecules. Only the collagen bound to the PIII-treated PTFE surface supported human dermal fibroblast attachment and spreading. This indicates that collagen on the PIII-treated surface possesses increased adhesive activity as compared to that on the untreated surface. Cell adhesion was inhibited by EDTA when the collagen was bound to PIII-treated PTFE, as expected for integrin involvement. Additionally this adhesion was sensitive to the conformation of the bound collagen. Increased actin cytoskeletal assembly was observed on cells spreading onto collagen-coated PIII-treated PTFE compared to the collagen-coated untreated PTFE. These data demonstrate the retention of collagen's biological properties following its attachment to PIII-treated PTFE, suggesting advantages for tissue engineering and prosthetic design.
The Vroman effect: Competitive protein exchange with dynamic multilayer protein aggregates
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.COLSURFB.2012.10.039
Abstract: The surface immobilization of proteins is an emerging field with applications in a wide range of important areas: biomedical devices, disease diagnosis, biosensing, food processing, biofouling, and bioreactors. Proteins, in Nature, often work synergistically, as in the important enzyme mixture, cellulase. It is necessary to preserve these synergies when utilizing surface immobilized proteins. However, the competitive displacement of earlier adsorbed proteins by other proteins with stronger binding affinities (the "Vroman effect") results in undesired layer instabilities that are difficult to control. Although this nanoscale phenomenon has been extensively studied over the last 40 years, the process through which this competitive exchange occurs is not well understood. This paper uses atomic force microscopy, QCM-D, TOF-SIMS, and in-solution TOF-MS to show that this competitive exchange process can occur through the turning of multilayer protein aggregates. This dynamic process is consistent with earlier postulated "transient complex" models, in which the exchange occurs in three stages: an initial layer adsorbs, another protein layer then embeds itself into the initial layer, forming a "transient complex " the complex "turns," exposing the first layer to solution proteins from the first layer desorb resulting in a final adsorbed protein composition that is enriched in proteins from the second layer.
13C NMR and FTIR study of thermal annealing of amorphous hydrogenated carbon
Publisher: Elsevier BV
Date: 1993
Enhancing the hardness of Al/W nanostructured coatings
Publisher: IOP Publishing
Date: 16-12-2009
DOI: 10.1088/0953-8984/21/5/055003
Abstract: Two-component multilayer thin films frequently show hardness enhancements at specific repeat periods above that of the constituent layers. This study of hardness enhancements in W/Al nanostructured coatings provides strong new evidence that hardness enhancements in this system arise not only from the presence of a layered structure, but also from the presence of defects introduced by changing the deposition conditions. S les with well defined layers of W and Al were produced by sputtering to cover a wide range of periods from 10 to 200 nm. No evidence of enhanced hardness in these films was found by nanoindentation. On the other hand, s les deposited from cathodic arc sources showed strong hardness enhancement above that of pure W. However, the s les of highest hardness did not contain Al layers for much of their thickness. The hardening mechanism therefore could not be attributed to the presence of a multilayer structure. Examination of the microstructure showed that the interruptions to the W deposition caused by operation of the Al source introduced defects which acted as pinning sites for dislocations. The nanoindentation hardness data were well described using a modified Hall-Petch relation.
Reaction pathways for pyridine adsorption on silicon (0 0 1)
Publisher: IOP Publishing
Date: 21-11-2014
DOI: 10.1088/0953-8984/27/5/054001
Abstract: Density functional theory is used to describe the reactions of chemisorption of pyridine on the silicon (0 0 1) surface. Adsorption energies of six relevant structures, and the activation energies between them are reported. We consider in detail the dative to tight-bridge transition for which conflicting results have been reported in the literature, and provide a description of the formation of inter-row chains observed in high-coverage experiments. We demonstrate that the choice of DFT functional has a considerable effect on the relative energetics and of the four DFT functionals considered, we find that the range-separated hybrid ωB97X-D functional with empirical dispersion provides the most consistent description of the experiment data.
The composition, structure and properties of four different glassy carbons
Publisher: Elsevier BV
Date: 10-2019
The structure of boron-, phosphorus- and nitrogen-doped tetrahedral amorphous carbon deposited by cathodic arc
Publisher: Elsevier BV
Date: 05-1994
The attachment of catalase and poly-l-lysine to plasma immersion ion implantation-treated polyethylene
Publisher: Elsevier BV
Date: 09-2007
DOI: 10.1016/J.ACTBIO.2007.02.005
Abstract: Plasma immersion ion implantation (PIII) treatment of polyethylene increased the functional attachment of catalase and increased the retention of enzyme activity in comparison to untreated controls. The attached protein was not removed by SDS or NaOH, while that on the untreated surfaces was easily removed. Poly-l-lysine was found to attach in a similar way to the treated surface and could not be removed by NaOH, while it did not attach to the untreated surface. This indicates that a new binding mechanism, covalent in nature, is introduced by the plasma treatment. Surfaces treated with PIII maintained the catalase activity more effectively than surfaces plasma treated without PIII. The PIII-treated surface was hydrophilic compared to the untreated surface and retained its hydrophilic character better than surfaces subjected to a conventional plasma treatment process. The strong modification of a deeper region of the polymer than for conventional plasma treatments is believed to be responsible for both the enhanced hydrophilic character and for the increase in functional lifetime of the attached protein. The results show that PIII treatment of polymers increases their usefulness for protein microarrays.
Cathodic arc deposition of solar thermal selective surfaces
Publisher: Elsevier BV
Date: 10-1996
Hemocompatibility and anti-bacterial properties of silver doped diamond-like carbon prepared by pulsed filtered cathodic vacuum arc deposition
Publisher: Elsevier BV
Date: 04-2007
A HiPIMS plasma source with a magnetic nozzle that accelerates ions: application in a thruster
Publisher: EDP Sciences
Date: 12-2016
Mechanisms for the behaviour of amorphous carbon films during annealing
Publisher: Oxford University Press (OUP)
Date: 08-2004
DOI: 10.1017/S1431927604886100
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.
Micro-arcing in radio frequency plasmas
Publisher: IOP Publishing
Date: 30-09-2004
A plasma ion bombardment process enabling reagent-free covalent binding of multiple functional molecules onto magnetic particles
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.MSEC.2018.12.106
Abstract: We report a plasma immersion ion implantation process for functionalizing polymer coated magnetic particles, converting them into a universal covalent binding platform for the simultaneous binding of multiple molecular agents without the need for specialised chemical linking groups. As an ex le, we demonstrate the improvement of wettability and the control of surface charge of polystyrene coated magnetic particles, enhancing biomolecule attachment density with strong covalent binding. We demonstrate the preparation of multifunctional magnetic particles where two or more types of molecule are co-immobilized. This enables a platform technology with simultaneous multiple covalent binding of molecules drawn from oligonucleotides, antibodies and enzymes suitable for targeted nanoparticle diagnostic and therapies.
Small field diode correction factors derived using an air core fibre optic scintillation dosimeter and EBT2 film
Publisher: IOP Publishing
Date: 13-04-2012
DOI: 10.1088/0031-9155/57/9/2587
Abstract: There is no commercially available real-time dosimeter that can accurately measure output factors for field sizes down to 4 mm without the use of correction factors. Silicon diode detectors are commonly used but are not dosimetrically water equivalent, resulting in energy dependence and fluence perturbation. In contrast, plastic scintillators are nearly dosimetrically water equivalent. A fibre optic dosimeter (FOD) with a 0.8 mm(3) plastic scintillator coupled to an air core light guide was used to measure the output factors for Novalis/BrainLab stereotactic cones of diameter 4-30 mm and Novalis MLC fields of width 5-100 mm. The FOD data matched the output factors measured by a 0.125 cm(3) Semiflex ion chamber for the MLC fields above 30 mm and those measured with the EBT2 radiochromic film for the cones and MLC fields below 30 mm. Relative detector readings were obtained with four diode types (IBA SFD, EFD, PFD, PTW 60012) for the same fields. Empirical diode correction factors were determined by taking the ratio of FOD output factors to diode relative detector readings. The diodes were found to over-respond by 3%-16% for the smallest field. There was good agreement between different diodes of the same model number.
Ion energy measurements during plasma immersion ion implantation of an insulator
Publisher: IOP Publishing
Date: 11-06-2010
Study of adhesion of TiN grown on a polymer substrate
Publisher: Elsevier BV
Date: 04-2007
Ion implanted, radical-rich surfaces for the rapid covalent immobilization of active biomolecules
Publisher: AIP
Date: 2013
DOI: 10.1063/1.4802352
Far-infrared transmission spectrum of thiourea
Publisher: Elsevier BV
Date: 12-1970
Light propagation in multimoded square hollow waveguides
Publisher: IOP Publishing
Date: 28-09-2012
Conducting carbon films with covalent binding sites for biomolecule attachment
Publisher: AIP Publishing
Date: 15-02-2019
DOI: 10.1063/1.5066565
Abstract: We report an electrically conductive carbon film with controllable hydrophilic properties that offers a covalent binding surface containing radicals for biomolecule attachment without using chemical linkers. Films were deposited from an acetylene-containing plasma using plasma immersion ion implantation during growth and subsequently annealed under vacuum. Electrical conductivity, spin density, contact angle, surface energy, surface composition, and covalent binding capability were studied as a function of annealing temperature, revealing three distinct regions. In the first region, surface energy is dominated by polar groups. In the second region, the polar groups are expelled, creating unpaired electrons that dominate the polar component of the surface energy. In the third region, the electrical conductivity rises and the polar component of surface energy falls as the unpaired electrons recombine, leading to an optimum combination of surface energy, spin density, and electrical conductivity for biological applications. It is proposed that persistent radicals are responsible for both high wettability and covalent binding properties. Covalently attached enzyme molecules on the C film can resist stringent washing with detergents. The C films offer the functions of conducting polymers, but with the added features of controllable wettability and a covalent binding capability.
Real‐time scintillation array dosimetry for radiotherapy: The advantages of photomultiplier detectors
Publisher: Wiley
Date: 08-03-2012
DOI: 10.1118/1.3690465
Abstract: In this paper, a photomultiplier tube (PMT) array dosimetry system has been developed and tested for the real-time readout of multiple scintillation signals from fiber optic dosimeters. It provides array dosimetry with the advantages in sensitivity provided by a PMT, but without the need for a separate PMT for each detector element. The PMT array system consisted of a multianode PMT, a multichannel data acquisition system, housing and optic fiber connections suitable for clinical use. The reproducibility, channel uniformity, channel crosstalk, acquisition speed, and sensitivity of the PMT array were quantified using a constant light source. Its performance was compared to other readout systems used in scintillation dosimetry. An in vivo HDR brachytherapy treatment was used as an ex le of a clinical application of the dosimetry system to the measurement of dose at multiple sites in the rectum. The PMT array system was also tested in the pulsed beam of a linear accelerator to test its response speed and its application with two separate methods of Cerenkov background removal. The PMT array dosimetry system was highly reproducible with a measurement uncertainty of 0.13% for a 10 s acquisition period. Optical crosstalk between neighboring channels was accounted for by omitting every second channel. A mathematical procedure was used to account for the crosstalk in next-neighbor channels. The speed and sensitivity of the PMT array system were found be superior to CCD cameras, allowing for measurement of more rapid changes in dose rate. This was further demonstrated by measuring the dose delivered by in idual photon pulses of a linear accelerator beam. The PMT array system has advantages over CCD camera-based systems for the readout of scintillation light. It provided a more sensitive, more accurate, and faster response to meet the demands of future developments in treatment delivery.
A review of in vitro experimental evidence for the effect of spatial and temporal modulation of radiation dose on response
Publisher: Informa UK Limited
Date: 16-06-2010
Plasma-Activated Substrate with a Tropoelastin Anchor for the Maintenance and Delivery of Multipotent Adult Progenitor Cells
Publisher: Wiley
Date: 25-09-2018
Abstract: Conventional wound therapy utilizes wound coverage to prevent infection, trauma, and fluid and thermal loss. However, this approach is often inadequate for large and/or chronic wounds, which require active intervention via therapeutic cells to promote healing. To address this need, a patch which delivers multipotent adult progenitor cells (MAPCs) is developed. Medical-grade polyurethane (PU) films are modified using plasma immersion ion implantation (PIII), which creates a radical-rich layer capable of rapidly and covalently attaching biomolecules. It is demonstrated that a short treatment duration of 400 s maximizes surface activation and wettability, minimizes reduction in gas permeability, and preserves the hydrolytic resistance of the PU film. The reactivity of PIII-treated PU is utilized to immobilize the extracellular matrix protein tropoelastin in a functional conformation that stably withstands medical-grade ethylene oxide sterilization. The PIII-treated tropoelastin-functionalized patch significantly promotes MAPC adhesion and proliferation over standard PU, while fully maintaining cell phenotype. Topical application of the MAPC-seeded patch transfers cells to a human skin model, while undelivered MAPCs repopulate the patch surface for subsequent cell transfer. The potential of this new wound patch as a reservoir for the sustained delivery of therapeutic MAPCs and cell-secreted factors for large and/or non-healing wounds is indicated in the findings.
Gas permeability reduction in PEEK film: Comparison of tetrahedral amorphous carbon and titanium nanofilm coatings
Publisher: Elsevier BV
Date: 08-2011
Energetic deposition of carbon clusters with preferred orientation using a new mixed mode cathodic arc – Sputtering process
Publisher: Elsevier BV
Date: 03-2010
The origin of preferred orientation during carbon film growth
Publisher: IOP Publishing
Date: 22-04-2009
DOI: 10.1088/0953-8984/21/22/225003
Abstract: Carbon films were prepared using a filtered cathodic vacuum arc deposition system operated with a substrate bias varying linearly with time during growth. Ion energies were in the range between 95 and 620 eV. Alternating dark, high density (sp(3) rich) bands and light, low density (sp(2) rich) bands were observed using cross-sectional transmission electron microscopy, corresponding to abrupt transitions between materials with densities of approximately 3.1 and 2.6 g cm(-3). No intermediate densities were observed in the s les. The low density bands show strong preferred orientation with graphitic sheets aligned normal to the film. After annealing, the low density bands became more oriented and the thinner high density layers were converted to low density material. In molecular dynamics modelling of film growth, temperature activated structural rearrangements occurring over long timescales ([Formula: see text] ps) caused the transition from sp(3) rich to oriented sp(2) rich structure. Once this oriented growth was initiated, the sputtering yield decreased and channelling was observed. However, we conclude that sputtering and channelling events, while they occur, are not the cause of the transition to the oriented structure.
Experimental investigation of plasma-immersion ion implantation treatment for biocompatible polyurethane implants production
Publisher: IOP Publishing
Date: 04-2016
Effect of ion modification of commonly used orthopedic materials on the attachment of human bone-derived cells
Publisher: Wiley
Date: 15-06-1999
DOI: 10.1002/(SICI)1097-4636(19990615)45:4<345::AID-JBM9>3.0.CO;2-J
Abstract: Biomaterials which combine optimum properties of strength and biocompatibility are desirable in improving the long-term performance of implantable medical devices. Our study is aimed at developing technology designed to alter the outer atomic layers of a material to give the desired compatibility with the tissue while retaining the properties of the bulk substratum. Materials used in this study were titanium vanadium alloy (Ti-6Al-4V) and cobalt chromium molybdenum alloy (Co-Cr). Soda lime glass discs and polyethylene terephthalate (PET) acted as controls. A cathode of either Ti-6Al-4V or Co-Cr was used to simultaneously deposit and implant identified substrata. The attachment of human bone-derived cells (HBDC) to various materials was determined using radiolabeling or colorimetric assays. Results show that HBDC adhere preferentially to the unmodified surfaces of Ti-6Al-4V and Ti-6Al-4V on glass compared to the unmodified Co-Cr surfaces and to that of the Co-Cr on glass. Depositing Ti-6Al-4V on Co-Cr gives significantly better attachment of HBDC than when depositing Co-Cr onto Ti-6Al-4V. While cellular attachment to the created surfaces reflects that of the cathodic materials, it is not identical to these materials. Ion deposition/implantation is capable of creating permanent surfaces which reflect the adhesion of source materials not bulk substrata.
Revisiting Maxwell’s accommodation coefficient: A study of nitrogen flow in a silica microtube across all flow regimes
Publisher: Elsevier BV
Date: 12-2014
Importance of charging in atomic resolution scanning tunneling microscopy: Study of a single phosphorus atom in a Si(001) surface
Publisher: American Physical Society (APS)
Date: 27-09-2006
Modelling of the mechanical behavior of a polyurethane finger interphalangeal joint endoprosthesis after surface modification by ion implantation
Publisher: IOP Publishing
Date: 04-2016
Mixed-mode high-power impulse magnetron sputter deposition of tetrahedral amorphous carbon with pulse-length control of ionization
Publisher: AIP Publishing
Date: 21-04-2016
DOI: 10.1063/1.4946841
Abstract: High-power impulse magnetron sputtering (HiPIMS) is used to deposit amorphous carbon thin films with sp3 fractions of 13% to 82%. Increasing the pulse length results in a transition from conventional HiPIMS deposition to a “mixed-mode” in which an arc triggers on the target surface, resulting in a large flux of carbon ions. The films are characterized using X-ray photoelectron spectroscopy, Raman spectroscopy, ellipsometry, nanoindentation, elastic recoil detection analysis, and measurements of stress and contact angle. All properties vary in a consistent manner, showing a high tetrahedral character only for long pulses, demonstrating that mixed-mode deposition is the source of the high carbon ion flux. Varying the substrate bias reveals an “energy window” effect, where the sp3 fraction of the films is greatest for a substrate bias around −100 V and decreases for higher or lower bias values. In the absence of bias, the films' properties show little dependence on the pulse length, showing that energetic ions are the origin of the highly tetrahedral character.
Enhanced Autohesive Bonding of Polyetheretherketone (PEEK) for Biomedical Applications Using a Methane/Oxygen Plasma Treatment
Publisher: Wiley
Date: 22-11-2010
Scintillators for 3D and 4D dosimetry: current status and future potential for clinical translation
Publisher: IOP Publishing
Date: 26-06-2013
A study of filter transport mechanisms in filtered cathodic vacuum arcs
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-1996
DOI: 10.1109/27.533126
A solid phase reaction between TiCx thin films and Al2O3 substrates
Publisher: AIP Publishing
Date: 15-03-2008
DOI: 10.1063/1.2896637
Abstract: Ti C x thin films were deposited on Al2O3 substrates at 900°C by using a multiple cathode high current pulsed cathodic arc. The Ti:C pulse ratio and, hence, the composition was varied from C rich to Ti rich. It is found that the Al2O3 substrate is decomposed and reacts with the TiCx film to incorporate significant amounts of O and Al in the growing film. When the stoichiometry is suitable, epitaxially oriented Ti2AlC MAX phase with significant O incorporated is formed. The results indicate that Al2O3 is not an ideal substrate material for the growth of transition metal carbides and MAX phase thin films.
The microstructure and stability of Al/AlN multilayered films
Publisher: AIP Publishing
Date: 07-2006
DOI: 10.1063/1.2204816
Abstract: Al ∕ Al N multilayers with bilayer thicknesses ranging from 10to50nm were fabricated using a filtered cathodic arc deposition system. The effects on the microstructure of using two different deposition rates and applying an 8kV pulsed voltage (plasma immersion ion implantation or PIII) to the substrate were explored. The microstructure was found to undergo a transition in which the Al transformed from layers to an aggregated phase under some conditions. This behavior is explained by a model in which the aggregation process is limited by diffusion. High deposition rates and the application of PIII were both found to encourage the transition by increasing diffusion. The model defines a phase diagram which predicts whether a multilayer or an aggregated structure will occur. A maximum in intrinsic stress was found to occur when the average feature size was 15nm for both layers and aggregates.
Čerenkov radiation in optical fibres
Publisher: IEEE
Date: 07-2006
Optical properties and oxidation of carbonized and cross-linked structures formed in polycarbonate by plasma immersion ion implantation
Publisher: Elsevier BV
Date: 06-2014
Laser fabrication of electrical feedthroughs in polymer encapsulations for active implantable medical devices
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.MEDENGPHY.2017.01.010
Abstract: Hermetic electrical feedthroughs are essential for safe and functional active implantable biomedical devices and for a wide range of other applications such as batteries, supercapacitors, OLEDs and solar cells. Ceramics and metals have previously been the materials of choice for encapsulations, while polymers have advantages of ease of mass production and end user compatibility. We demonstrate a laser sealing technology that gives hermetic, mechanically strong feedthroughs with low electrical resistance in a polyetheretherketone (PEEK) encapsulation. The conductive pathways are wires and sputtered thin films. The water vapor transmission rate through the fabricated encapsulations is comparable to that of PEEK itself.
NMR evidence for strained carbon bonding in tetrahedral amorphous carbon
Publisher: Elsevier BV
Date: 04-1995
Ion implantation treatment of beads for covalent binding of molecules: Application to bioethanol production using thermophilic beta-glucosidase
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.ENZMICTEC.2013.09.012
Abstract: We have achieved plasma immersion ion implantation (PIII) treatment of beads and powders using a specially designed plasma treatment system. This simple one-step production of functionalized beads provides an attractive alternative to current commercial functional beads, for which proteins must be chemically attached using linkers. Using the enzyme beta-glucosidase as an ex le we show that PIII treatment of polyethylene beads enables covalent binding with increased activity of the enzyme compared to the untreated beads. Covalent binding was confirmed using detergent washing. The covalently immobilized enzyme has a broader pH range over which it has high activity than the enzyme in solution. The stability of the immobilized molecules was examined using reaction rate as a function of temperature and was shown to be significantly higher on the PIII treated beads compared to untreated beads. We attribute the increased enzyme activity on PIII treated beads to increased protein binding density and better retention of conformation. The results of this work are of significance in the production of ethanol using a flow process. Covalent binding to beads allows more robust attachment for high flow rates, high activity, large surface area and a broad operating pH range. Treatment could be easily adapted for a range of applications such as linking drugs, dyes and proteins to particles of an appropriate size.
n-type doping of highly tetrahedral diamond-like amorphous carbon
Publisher: IOP Publishing
Date: 29-03-1993
Direct Evidence of Covalent Immobilisation of Microperoxidase‐11 on Plasma Polymer Surfaces
Publisher: Wiley
Date: 30-06-2010
Biological Effects of Electromagnetic Fields—Mechanisms for the Effects of Pulsed Microwave Radiation on Protein Conformation
Publisher: Elsevier BV
Date: 09-2000
The distribution and depth of ion doses implanted into wedges by plasma immersion ion implantation in drifting and stationary plasmas
Publisher: IOP Publishing
Date: 27-04-2006
Properties of tetrahedral amorphous carbon prepared by vacuum arc deposition
Publisher: Elsevier BV
Date: 08-1991
Nanocrystalline hexagonal diamond formed from glassy carbon
Publisher: Springer Science and Business Media LLC
Date: 29-11-2016
DOI: 10.1038/SREP37232
Abstract: Carbon exhibits a large number of allotropes and its phase behaviour is still subject to significant uncertainty and intensive research. The hexagonal form of diamond, also known as lonsdaleite, was discovered in the Canyon Diablo meteorite where its formation was attributed to the extreme conditions experienced during the impact. However, it has recently been claimed that lonsdaleite does not exist as a well-defined material but is instead defective cubic diamond formed under high pressure and high temperature conditions. Here we report the synthesis of almost pure lonsdaleite in a diamond anvil cell at 100 GPa and 400 °C. The nanocrystalline material was recovered at ambient and analysed using diffraction and high resolution electron microscopy. We propose that the transformation is the result of intense radial plastic flow under compression in the diamond anvil cell, which lowers the energy barrier by “locking in” favourable stackings of graphene sheets. This strain induced transformation of the graphitic planes of the precursor to hexagonal diamond is supported by first principles calculations of transformation pathways and explains why the new phase is found in an annular region. Our findings establish that high purity lonsdaleite is readily formed under strain and hence does not require meteoritic impacts.
Interactions of the directed plasma from a cathodic arc with electrodes and magnetic fields
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 1996
DOI: 10.1109/27.538803
A comprehensive model of stress generation and relief processes in thin films deposited with energetic ions
Publisher: Elsevier BV
Date: 04-2006
Analysis of films prepared by plasma polymerization of acetylene in a D.C. magnetron
Publisher: Elsevier BV
Date: 10-1983
Profiling of the secretome of human cancer cells: Preparation of supernatant for proteomic analysis
Publisher: Wiley
Date: 28-07-2014
Abstract: Secretomic analysis requires removal of serum proteins from cell-culture media. We evaluate the proteins washed from cells prepared in bovine serum-supplemented medium. PBS and serum-free-medium (SFM) were the washing solutions. A Bradford assay was used for total protein concentration and a 1D gel and LC-MS/MS, to assign the protein to human or bovine origin. For both wash solutions, all bovine protein had been removed by the third wash, without compromising the number of living cells. Further washes reduced the number of living cells, especially when using PBS. Proteomic analysis of wash supernatant showed that SFM induced greater lysis of dead cells. Three washes were sufficient to minimize the effects on cell viability, while still removing serum proteins. Washing in SFM resulted in contamination of the wash supernatant with lysed dead cell proteins. Washed cells were incubated in SFM and exposed to ionizing radiation. Analysis of the supernatant showed an increase in human cytoplasmic, plasma membrane, and nuclear protein following irradiation. Secreted proteins were also detected, but in smaller quantities. The significance of these findings extend to in vitro studies of bystander phenomena, since the proteins of lysed dead cells may participate in driving bystander responses.
Covalent linker-free immobilization of conjugatable oligonucleotides on polypropylene surfaces
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA16034D
Abstract: A novel plasma treatment method was used to activate a polymer surface for oligonucleotide immobilization.
Carbon coating of Ti-6Al-4V for reduced wear in combined impact and sliding applications
Publisher: Elsevier BV
Date: 12-2003
Characteristics of titanium arc evaporation processes
Publisher: Elsevier BV
Date: 10-1987
Production of amorphous carbon by plasma immersion ion implantation of polymers
Publisher: Elsevier BV
Date: 10-2005
Properties of indium tin oxide films prepared by ion-assisted deposition
Publisher: Elsevier BV
Date: 03-1986
Electronic structure of two interacting phosphorusδ
Publisher: American Physical Society (APS)
Date: 11-01-2013
Compressive-stress-induced formation of thin-film tetrahedral amorphous carbon
Publisher: American Physical Society (APS)
Date: 05-08-1991
Analysis of graded metal-carbon films produced by dual-cathode sputtering
Publisher: Elsevier BV
Date: 05-1982
Spatial variations in the stoichiometry of sputtered YBaCuO thin films: theory and experiment
Publisher: Elsevier BV
Date: 10-1990
A prototype scintillation dosimeter customized for small and dynamic megavoltage radiation fields
Publisher: IOP Publishing
Date: 28-01-2010
DOI: 10.1088/0031-9155/55/4/014
Abstract: A prototype plastic scintillation dosimeter has been developed with a small sensitive volume, rapid response and good dosimetric performance. The novelty of this design is the use of an air core light guide to transport the scintillation signal out of the primary radiation field. The significance of this innovation is that it eliminates the Cerenkov background signal that is generated in conventional optical fibres. The dosimeter performance was compared to existing commercial dosimeters in 6 MV and 18 MV photon beams and 6 MeV and 20 MeV electron beams, in both static and dynamic fields. The dosimeter was tested in small static fields and in dynamically delivered fields where the detector volume is shielded, while the stem is irradiated. The depth dose measurements for the photon beams agreed with ionization chamber measurements to within 1.6%, except in the build-up region due to positional uncertainty. For the 6 MeV and 20 MeV electron beams, the percentage depth dose measurements agreed with the ionization chamber measurements to within 3.6% and 4.5%, respectively. For field sizes of 1 cm x 1 cm and greater, the air core dosimeter readings agreed with diamond detector readings to within 1.2%. The air core dosimeter was accurate in dynamically delivered fields and had no measurable stem effect. The air core dosimeter was accurate over a range of field sizes, energies and dose rates, confirming that it is a sensitive and accurate dosimeter with high spatial resolution suitable for use in megavoltage photon and electron beams.
Array of square waveguides for scintillation dosimetry in external radiotherapy
Publisher: IOP Publishing
Date: 26-06-2013
Dielectric substrate self-bias and plasma confinement in two-dimensional scanning radio frequency plasma-enhanced chemical vapour deposition
Publisher: Elsevier BV
Date: 11-2006
Minimisation of intrinsic stress in titanium nitride using a cathodic arc with plasma immersion ion implantation
Publisher: Elsevier BV
Date: 09-2003
Molecular dynamics and experimental studies of preferred orientation induced by compressive stress
Publisher: Elsevier BV
Date: 12-1995
Ion implantation induced phase transformation in carbon and boron nitride thin films
Publisher: Elsevier BV
Date: 08-2005
Raman characterisation of PIII multilayer carbon films
Publisher: Elsevier BV
Date: 04-2004
Thermodynamic theory for preferred orientation in materials prepared by energetic condensation
Publisher: Elsevier BV
Date: 02-2001
The role of energetic ions from plasma in the creation of nanostructured materials and stable polymer surface treatments
Publisher: Elsevier BV
Date: 2006
The structure and electronic properties of tetrahedrally bonded hydrogenated amorphous carbon
Publisher: AIP Publishing
Date: 05-2023
DOI: 10.1063/5.0147494
Abstract: We have synthesized hydrogenated and deuterated amorphous carbon materials that have a density, 2.7 ± 0.1 g/cm3, consistent with almost entirely tetrahedral bonding. In hydrogen-free tetrahedral amorphous carbon, the presence of a minority of sp2 bonded atoms leads to localized states that could be passivated with hydrogen by analogy with hydrogenated amorphous silicon. Neutron diffraction analysis demonstrated that the local bonding environment is consistent with ab initio models of high density hydrogenated tetrahedral amorphous carbon and with the related tetrahedral molecular structure neopentane. The optical bandgap of our material, 4.5 eV, is close to the bandgap in the density of states determined by scanning tunneling spectroscopy (4.3 eV). This bandgap is considerably larger than that of hydrogen-free tetrahedral amorphous carbon, confirming that passivation of sp2 associated tail-states has occurred. Both the structural and electronic measurements are consistent with a model in which the tetrahedrally bonded carbon regions are terminated by hydrogen, causing hopping conductivity to dominate.
The mechanical response of glassy carbon recovered from high pressure
Publisher: AIP Publishing
Date: 14-04-2020
DOI: 10.1063/1.5142309
Abstract: Glassy carbon (GC) is usually considered the prototypical super-elastic material, which can almost fully recover its shape after compression of several gigapascals (GPa). In this work, nanoindentation is used to study the mechanical response of GC, which was subjected to a range of high pressures using a diamond anvil cell (DAC). We show that GC starts to lose its elasticity after compression to 6 GPa and becomes clearly mechanically anisotropic after being compressed beyond ∼30 GPa. Molecular dynamics (MD) simulations are used to calculate Young's modulus before and after compression. Through our experimental results and MD simulations, we show that the elasticity of GC is at a minimum around 30 GPa but recovers after compression to higher pressures along the DAC compression axis.
Ab initiosimulations of nitrogen evolution in quenchedC
Publisher:
American Physical Society (APS)
Date:
15-08-2005
Publisher: American Physical Society (APS)
Date: 15-08-2005
Autohesion of plasma treated semi-crystalline PEEK: Comparative study of argon, nitrogen and oxygen treatments
Publisher: Elsevier BV
Date: 2011
Synthesis of highly tetrahedral amorphous carbon by mixed-mode HiPIMS sputtering
Publisher: IOP Publishing
Date: 09-10-2015
Mechanisms for surface energy changes observed in plasma immersion ion implanted polyethylene: The roles of free radicals and oxygen-containing groups
Publisher: Elsevier BV
Date: 04-2009
The immobilization of recombinant human tropoelastin on metals using a plasma-activated coating to improve the biocompatibility of coronary stents
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.BIOMATERIALS.2010.07.062
Abstract: Current endovascular stents have sub-optimal biocompatibility reducing their clinical efficacy. We previously demonstrated a plasma-activated coating (PAC) that covalently bound recombinant human tropoelastin (TE), a major regulator of vascular cells in vivo, to enhance endothelial cell interactions. We sought to develop this coating to enhance its mechanical properties and hemocompatibility for application onto coronary stents. The plasma vapor composition was altered by incorporating argon, nitrogen, hydrogen or oxygen to modulate coating properties. Coatings were characterized for 1) surface properties, 2) mechanical durability, 3) covalent protein binding, 4) endothelial cell interactions and 5) thrombogenicity. The N(2)/Ar PAC had optimal mechanical properties and did not delaminate after stent expansion. The N(2)/Ar PAC was mildly hydrophilic and covalently bound the highest proportion of TE, which enhanced endothelial cell proliferation. Acute thrombogenicity was assessed in a modified Chandler loop using human blood. Strikingly, the N(2)/Ar PAC alone reduced thrombus weight by ten-fold compared to 316L SS, a finding unaltered with immobilized TE. Serum soluble P-selectin was reduced on N(2)/Ar PAC and N(2)/Ar PAC + TE (p < 0.05), consistent with reduced platelet activation. We have demonstrated a coating for metal alloys with multifaceted biocompatibility that resists delamination and is non-thrombogenic, with implications for improving coronary stent efficacy.
Intrafractional motion during proton beam scanning
Publisher: IOP Publishing
Date: 04-10-2005
DOI: 10.1088/0031-9155/50/20/008
Abstract: Patient and internal organ motion during treatment with a scanned proton beam can introduce unplanned heterogeneities in the dose distribution throughout the irradiated volume. With static beam techniques, a margin around the target volume is added to compensate for patient and organ motion. This margin may not provide the solution with dynamic beam scanning. Intrafractional motion parallel and perpendicular to the beam axis is studied using two different scanning methods on a cubic water phantom. The direction of motion relative to the beam scanning direction as well as the method of scanning the proton beam across the target has a significant effect on the resulting dose distribution within the target volume. In the extreme cases studied here up to 100% of the target receives a dose outside the recommended limits, with a minimum dose as low as 34% of the prescribed dose.
Characterization of cathodic arc deposited titanium aluminium nitride films prepared using plasma immersion ion implantation
Publisher: IOP Publishing
Date: 15-04-2005
A post Gurney quantum mechanical perspective on the electrolysis of water: ion neutralization in solution
Publisher: The Royal Society
Date: 11-2017
Abstract: Electron fluxes crossing the interface between a metallic conductor and an aqueous environment are important in many fields hydrogen production, environmental scanning tunnelling microscopy, scanning electrochemical microscopy being some of them. Gurney (Gurney 1931 Proc. R. Soc. Lond. 134 , 137 (doi:10.1098/rspa.1931.0187)) provided in 1931 a scheme for tunnelling during electrolysis and outlined conditions for it to occur. We measure the low-voltage current flows between gold electrodes in pure water and use the time-dependent behaviour at voltage switch-on and switch-off to evaluate the relative contribution to the steady current arising from tunnelling of electrons between the electrodes and ions in solution and from the neutralization of ions adsorbed onto the electrode surface. We ascribe the larger current contribution to quantum tunnelling of electrons to and from ions in solution near the electrodes. We refine Gurney's barrier scheme to include solvated electron states and quantify energy differences using updated information. We show that Gurney's conditions would prevent the current flow at low voltages we observe but outline how the ideas of Marcus (Marcus 1956 J. Chem. Phys. 24 , 966–978 (doi:10.1063/1.1742723)) concerning solvation fluctuations enable the condition to be relaxed. We derive an average barrier tunnelling model and a multiple pathways tunnelling model and compare predictions with measurements of the steady-state current–voltage relation. The tunnelling barrier was found to be wide and low in agreement with other experimental studies. Applications as a biosensing mechanism are discussed that exploit the fast tunnelling pathways along molecules in solution.
Initial growth of conducting island-like structure on insulating polymer substrate
Publisher: IEEE
Date: 2008
Plasma processing of PDMS based spinal implants for covalent protein immobilization, cell attachment and spreading
Publisher: Springer Science and Business Media LLC
Date: 30-11-2018
DOI: 10.1007/S10856-018-6181-Y
Abstract: PDMS is widely used for prosthetic device manufacture. Conventional ion implantation is not a suitable treatment to enhance the biocompatibility of poly dimethyl siloxane (PDMS) due to its propensity to generate a brittle silicon oxide surface layer which cracks and delaminates. To overcome this limitation, we have developed new plasma based processes to balance the etching of carbon with implantation of carbon from the plasma source. When this carbon was implanted from the plasma phase it resulted in a surface that was structurally similar and intermixed with the underlying PDMS material and not susceptible to delamination. The enrichment in surface carbon allowed the formation of carbon based radicals that are not present in conventional plasma ion immersion implantation (PIII) treated PDMS. This imparts the PDMS surfaces with covalent protein binding capacity that is not observed on PIII treated PDMS. The change in surface energy preserved the function of bound biomolecules and enhanced the attachment of MG63 osteosarcoma cells compared to the native surface. The attached cells, an osteoblast interaction model, showed increased spreading on the treated over untreated surfaces. The carbon-dependency for these beneficial covalent protein and cell linkage properties was tested by incorporating carbon from a different source. To this end, a second surface was produced where carbon etching was balanced against implantation from a thin carbon-based polymer coating. This had similar protein and cell-binding properties to the surfaces generated with carbon inclusion in the plasma phase, thus highlighting the importance of balancing carbon etching and deposition. Additionally, the two effects of protein linkage and bioactivity could be combined where the cell response was further enhanced by covalently tethering a biomolecule coating, as exemplified here with the cell adhesive protein tropoelastin. Providing a balanced carbon source in the plasma phase is applicable to prosthetic device fabrication as illustrated using a 3-dimensional PDMS balloon prosthesis for spinal implant applications. Consequently, this study lays the groundwork for effective treatments of PDMS to selectively recruit cells to implantable PDMS fabricated biodevices.
Sticky nano-thin films for the adhesion of polymers
Publisher: Elsevier BV
Date: 11-2013
Anomalous voltage-current characteristics in the sputtering of YBaCuO
Publisher: Elsevier BV
Date: 11-1991
Gold black and gold cermet absorbing surfaces
Publisher: Springer Science and Business Media LLC
Date: 06-1978
DOI: 10.1007/BF03215450
The orientation dependence of elastic strain energy in cubic crystals and its application to the preferred orientation in titanium nitride thin films
Publisher: IOP Publishing
Date: 05-08-1996
Surface plasma modification and tropoelastin coating of a polyurethane co-polymer for enhanced cell attachment and reduced thrombogenicity
Publisher: Elsevier BV
Date: 08-2014
DOI: 10.1016/J.BIOMATERIALS.2014.04.082
Abstract: Polymers currently utilized for dermal and vascular applications possess sub-optimal biocompatibility which reduces their efficacy. Improving the cell-binding and blood-contacting properties of these polymers would substantially improve their clinical utility. Tropoelastin is a highly extensible extracellular matrix protein with beneficial cell interactive and low thrombogenic properties. We transferred these benefits to the polyurethane block copolymer Elast-Eon E2A through a specific combination of surface plasma modifications and coating with human tropoelastin. The cell-binding activity of bound tropoelastin was modulated by ion implantation of the underlying polymer, and correlated with surface hydrophobicity, carbon and oxygen content. This combined treatment enhanced human dermal fibroblast (HDF) and human umbilical vein endothelial cell (HUVEC) attachment, cytoskeletal assembly and viability, combined with elevated PECAM-1 staining of HUVEC cell junctions. The thrombogenicity of the polymer was ameliorated by tropoelastin coating. We propose that a combination of metered plasma treatment and tropoelastin coating of Elast-Eon can serve to improve the biological performance of implantable devices such as vascular conduits.
Small field detector correction factors: effects of the flattening filter for Elekta and Varian linear accelerators
Publisher: Wiley
Date: 05-2016
The shear-driven transformation mechanism from glassy carbon to hexagonal diamond
Publisher: Elsevier BV
Date: 02-2019
Nanoindentation response of PEEK modified by mesh-assisted plasma immersion ion implantation
Publisher: Elsevier BV
Date: 06-2007
Wannier function analysis of tetrahedral amorphous networks
Publisher: Elsevier BV
Date: 10-2003
N-type doping of germanium from phosphine: Early stages resolved at the atomic level
Publisher: American Physical Society (APS)
Date: 13-08-2012
Optical properties of thin amorphous silicon and amorphous hydrogenated silicon films produced by ion beam techniques
Publisher: Elsevier BV
Date: 02-1983
The structural phases of non-crystalline carbon prepared by physical vapour deposition
Publisher: Elsevier BV
Date: 11-2009
Plasma deposited high surface area‐activated carbon coatings: Theory combining particle generation, aggregation and deposition explains microstructure
Publisher: Wiley
Date: 15-04-2022
Abstract: High surface area carbon coatings are produced by plasma‐enhanced chemical vapour deposition using a high‐voltage dielectric barrier discharge under conditions where aggregates are formed in the plasma and the growing coating is subjected to plasma immersion ion implantation. We extend the Smoluchowski aggregation theory to include the continuous production of monomers to explain the observed microstructure of the coatings as a function of the pressure of deposition. The larger particles show evidence of the accretion of monomers on their surfaces with characteristic voids resulting from island growth. The coatings are subjected to plasma immersion ion implantation using high‐voltage pulses that create radicals for binding biomolecules. The increased surface area by the presence of the aggregated particles binds a significantly higher amount of protein than smooth coatings, making them potentially useful for electrodes, biosensing and drug delivery.
Synthesis, structure and applications of amorphous diamond
Publisher: Elsevier BV
Date: 12-1991
Molecular dynamics study of ion impact phenomena
Publisher: IOP Publishing
Date: 19-09-1994
Codeposition of amorphous zinc tin oxide using high power impulse magnetron sputtering: characterisation and doping
Publisher: IOP Publishing
Date: 21-03-2017
Small field correction factors for the IBA Razor
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.EJMP.2016.07.004
Abstract: The IBA Razor diode supersedes the IBA SFD and is intended for use in small fields. However, its behaviour in small fields has not yet been quantified. In this work, we examine the response of the Razor diode against the air core scintillation dosimeter (FOD) and Gafchromic film in photon beams from three Varian linac beams. Fields between 4mm and 30mm in width were measured, both with and without a flattening filter and at two energies. The Razor exhibited an over-response of up to 4.5% for MLC collimated fields and 7.1% for stereotactic cone collimated fields. The presence of the flattening filter altered the over-response by up to 1.5%. The small field correction factors are tabulated and agree with the mathematical relation of Liu et al. (2014). Four s les of the Razor were used, two having received a significant prior dose. The correction factors for the four s les differed and may depend on their dose history.
An electron diffraction study of amorphous hydrogenated germanium-carbon thin films
Publisher: AIP Publishing
Date: 10-1990
DOI: 10.1063/1.346369
Abstract: The structure of a-Ge1−xCx:H films produced by glow-discharge decomposition of germane and methane gases has been studied by electron diffraction. The reduced density function of five films for different values of x shows evidence that germanium and carbon form a bond in the amorphous solid state. The structure does not correspond to the tetrahedrally bonded network of the amorphous silicon-carbon analogue but consists of molecular fragments and has a low stability.
Influence of gas entry point on plasma chemistry, ion energy and deposited alumina thin films in filtered cathodic arc
Publisher: Springer Science and Business Media LLC
Date: 03-07-2007
Over-response of synthetic microDiamond detectors in small radiation fields
Publisher: IOP Publishing
Date: 11-09-2014
DOI: 10.1088/0031-9155/59/19/5873
Abstract: The recently commercialized PTW microDiamond detector (T60019) has been designed for use in small radiation fields. Here we report on the measurement of relative output ratios for small fields using five microDiamond detectors. All of the microDiamond detectors over-responded in fields smaller than 20 mm, by up to 9.3% for a 4 mm field. The over-response was independent of accelerator type and choice of collimation. The over-response was slightly larger than that observed in silicon diodes. Since all five microDiamond detectors showed the same over-response the corrections presented here should be transferable to other ex les of the microDiamond detector, provided that the detector meets the manufacturing specifications and the beam characteristics are comparable.
Kinetics of post-treatment structural transformations of nitrogen plasma ion immersion implanted polystyrene
Publisher: Elsevier BV
Date: 06-2013
A Comparison of Covalent Immobilization and Physical Adsorption of a Cellulase Enzyme Mixture
Publisher: American Chemical Society (ACS)
Date: 12-08-2010
DOI: 10.1021/LA1019845
Abstract: This paper reports the first use of a linker-free covalent approach for immobilizing an enzyme mixture. Adsorption from a mixture is difficult to control due to varying kinetics of adsorption, variations in the degree of unfolding and competitive binding effects. We show that surface activation by plasma immersion ion implantation (PIII) produces a mildly hydrophilic surface that covalently couples to protein molecules and avoids these issues, allowing the attachment of a uniform monolayer from a cellulase enzyme mixture. Atomic force microscopy (AFM) showed that the surface layer of the physically adsorbed cellulase layer on the mildly hydrophobic surface (without PIII) consisted of aggregated enzymes that changed conformation with incubation time. The evolution observed is consistent with the existence of transient complexes previously postulated to explain the long time constants for competitive displacement effects in adsorption from enzyme mixtures. AFM indicated that the covalently coupled bound layer to the PIII-treated surface consisted of a stable monolayer without enzyme aggregates, and became a double layer at longer incubation times. Light scattering analysis showed no indication of aggregates in the solution at room temperature, which indicates that the surface without PIII-treatment induced enzyme aggregation. A model for the attachment process of a protein mixture that includes the adsorption kinetics for both surfaces is presented.
The influence of deposition rate on the stress and microstructure of AlN films deposited from a filtered cathodic vacuum arc
Publisher: Elsevier BV
Date: 03-2011
Phosphine adsorption and dissociation on the Si(001) surface: An ab initio survey of structures
Publisher: American Physical Society (APS)
Date: 19-09-2005
dc magnetron production of amorphous silicon solar cells
Publisher: AIP Publishing
Date: 15-10-1984
DOI: 10.1063/1.334274
Abstract: The operation of a dc cylindrical magnetron with a stainless-steel cathode in silane gas was investigated. Coating rates up to 0.15 μm/min were obtained for hydrogenated amorphous silicon (a-Si:H). The photoconductivity of the films was slightly dependent on coating rate. The optical properties of the films were investigated and found to be an indicator of film quality. The infrared spectra and photoconductive properties of doped films were also studied. Solar cells of the p-n type in which the p layer is either a-Si:H or a-SixC1−x:H were made and their performance studied. It was concluded that the dc magnetron is capable of producing good cells with higher deposition rates than previously obtainable.
Characterization of small-field stereotactic radiosurgery beams with modern detectors
Publisher: IOP Publishing
Date: 10-10-2013
DOI: 10.1088/0031-9155/58/21/7595
Abstract: To derive accurate beam models for stereotactic radiosurgery (SRS) planning it is necessary to characterize the beam with dosimetric measurements. The aim of this study is to identify the best detectors for each task in the characterization process. Output ratios, beam profiles and percentage depth doses were measured for SRS cone diameters of 5-45 mm. Commercially available and emerging detectors were used: Gafchromic EBT2 film, an air-core fibre optic dosimeter (FOD) (developed at Royal Prince Alfred Hospital, Sydney), an IBA stereotactic field diode, a PTW 60012 electron diode and an IBA cc01 small volume thimble ion chamber. Analysis of the measured data supported by baseline Monte Carlo simulation data, led to the following recommendations: (1) water-equivalent detectors (Gafchromic EBT2 film or FOD) are the preferred choice for SRS dosimetry, (2) ion chambers (including small volume chambers with high-density central electrodes) should be avoided due to volume averaging effects and energy dependence, (3) if diodes are used, corrections must be made to account for their over-response in small fields.
CelB and β-glucosidase immobilization for carboxymethyl cellulose hydrolysis
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3RA43666G
A comprehensive survey of M2AX phase elastic properties
Publisher: IOP Publishing
Date: 08-07-2009
DOI: 10.1088/0953-8984/21/30/305403
Abstract: M(2)AX phases are a family of nanolaminate, ternary alloys that are composed of slabs of transition metal carbide or nitride (M(2)X) separated by single atomic layers of a main group element. In this combination, they manifest many of the beneficial properties of both ceramic and metallic compounds, making them attractive for many technological applications. We report here the results of a large scale computational survey of the elastic properties of all 240 elemental combinations using first-principles density functional theory calculations. We found correlations revealing the governing role of the A element and its interaction with the M element on the c axis compressibility and shearability of the material. The role of the X element is relatively minor, with the strongest effect seen in the in-plane constants C(11) and C(12). We identify several elemental compositions with extremal properties such as W(2)SnC, which has by far the lowest value of C(44), suggesting potential applications as a high-temperature dry lubricant.
Characterization of a filtered high current pulsed cathodic vacuum arc plasma source: Plasma transport analysis
Publisher: AIP
Date: 2008
DOI: 10.1063/1.2909142
Plasma activated liquid synergistically enhances response to radiation for improved cancer therapy
Publisher: Wiley
Date: 29-05-2022
Abstract: Plasma activated liquid (PAL) is an emerging cancer treatment. Two prostate cell lines and one melanoma cell line were used in clonogenic assays to assess the cytotoxicity of PAL and radiation in idually and in combination, using the multiplicative survival method to quantify interactions between the treatments. PAL applied before a dose of radiation synergistically increases cytotoxicity in cancer cells, while in immortalized normal cells, the combined treatment was found to be antagonistic. These results demonstrate the potential to improve the therapeutic window of cancer treatment, giving a higher cancer response rate with less toxicity.
Electromagnetic radiation at 835 MHz changes the morphology and inhibits proliferation of a human astrocytoma cell line
Publisher: Elsevier BV
Date: 06-1997
Prediction of reflectance of metal carbon solar absorbing films for their enhancement by annealing
Publisher: Elsevier BV
Date: 07-1982
Free radicals created by plasmas cause autohesive bonding in polymers
Publisher: AIP Publishing
Date: 23-05-2011
DOI: 10.1063/1.3592259
Abstract: We find that plasma immersion ion implantation of polymer surfaces enhances their autohesive bond strength when pressed together by more than a factor of five. Both polymerising (CH4/O2) and nonpolymerising (Ar) plasmas are effective. There is currently no satisfactory theory for predicting this remarkable phenomenon. We propose that free radicals created by the plasma treatment process diffuse to the interface and cause covalent bonds to form. This theory predicts the dependence of bond strength on plasma bias voltage, treatment time, and autohesive process conditions.
Tomographic interferometry of a filtered high-current vacuum arc plasma
Publisher: AIP Publishing
Date: 04-2007
DOI: 10.1063/1.2714677
Abstract: Tomography of a plasma enables the distribution of electron density to be visualized. We report on the design of two tomographic interferometer systems used to measure plasma electron density distributions in a high-current pulsed cathodic vacuum arc. The method is shown to be capable of microsecond time resolution. The spatial resolution of the quasioptical interferometer operating at 2 mm wavelength is 20 mm and the spatial resolution of the waveguide-based interferometer operating at 8 mm wavelength is 50 mm. In both cases the resolution achieved depends on the launching and receiving geometries. We developed criteria for assessing the tomogram for artifacts arising from limited s ling. First results of the spatial and temporal history of plasma in a high-current vacuum arc guided by a curved magnetic filter are presented and indicate poloidal field fluctuations reminiscent of magnetohydrodynamic instabilities in pinches. The applicability of the tomographic interferometry method to optimize plasma transport through the filter is also demonstrated.
Covalently bound biomimetic layers on plasma polymers with graded metallic interfaces for in vivo implants
Publisher: Wiley
Date: 13-10-2009
Cerenkov-free scintillation dosimetry in external beam radiotherapy with an air core light guide
Publisher: IOP Publishing
Date: 19-05-2008
DOI: 10.1088/0031-9155/53/11/021
Abstract: Plastic scintillators have many advantages for dosimetry in external beam radiotherapy. The current method of transmitting the scintillation light to a remote detector is through a solid core optical fibre. When exposed in a high energy therapeutic radiotherapy beam this fibre is subject to an unwanted background signal from Cerenkov light which can exceed the scintillation signal at characteristic angles. We have constructed a plastic scintillation dosimeter that uses an air core light guide to transport the light from the scintillator to the light detector. We show that there is sufficient signal propagation in the air core light guide to allow the scintillator signal to be carried outside the primary beam of a radiotherapy linear accelerator and for a dosimeter to be constructed using a scintillator inserted into the end of the light guide. Studies of the background light generated in the air core light guide, as a function of the angle between the beam and the fibre axis, show that there is no characteristic Cerenkov peak generated in the air core. Depth dose measurements using the air core scintillation dosimeter with no correction for Cerenkov are compared to ionization chamber measurements for a 6 MV photon beam and a 9 MeV electron beam.
Bio-functionalisation of polyether ether ketone using plasma immersion ion implantation
Publisher: SPIE
Date: 22-12-2015
DOI: 10.1117/12.2202506
A technique for microsecond heating and cooling of a thin (submicron) biological sample
Publisher: Springer Science and Business Media LLC
Date: 08-2002
DOI: 10.1007/S00249-002-0228-0
Abstract: Temperature excursions of short duration are useful in exploring the effects of stress on biological systems. Stress will affect the conformation of biological molecules such as proteins, which will lead to an effect on their function. The feasibility of generating such temperature excursions is demonstrated by solving the heat diffusion equation for an aqueous layer on a silicon wafer. The silicon is rapidly heated by a laser pulse and also acts as a heat sink to quench the temperature rise. An oxide layer was used to limit the maximum temperature attained by the s le. We show that exposures above a 50 degrees C benchmark can be confined to times less than 5 micros.
Atomic-scale observation and control of the reaction of phosphine with silicon
Publisher: Surface Science Society Japan
Date: 2006
Single Phosphorus Atoms in Si(001): Doping-Induced Charge Transfer into Isolated Si Dangling Bonds
Publisher: American Chemical Society (ACS)
Date: 07-04-2007
DOI: 10.1021/JP068834C
The antiferroelectric transition in thiourea studied by thermal neutron scattering
Publisher: IOP Publishing
Date: 07-06-1975
An interferometric investigation of the thermalization of copper atoms in a magnetron sputtering discharge
Publisher: AIP Publishing
Date: 02-1986
DOI: 10.1063/1.336589
Abstract: The average kinetic energy of the atoms sputtered from the copper cathode of a magnetron sputtering discharge has been deduced from the shapes of their Doppler-broadened emission lines, which were measured with a high-resolution scanning Fabry–Perot interferometer. At a fixed distance from the cathode the energy decreased with increasing sputtering gas pressure, as expected. The experimental points fell between the theoretical curves of Westwood [J. Vac. Sci. Technol. 15, 1 (1978)], and Meyer, Schuller, and Falco [J. Appl. Phys. 52, 5803 (1981)] lying somewhat closer to the former than to the latter.
A comparative study of the on-off switching behavior of metal-insulator-metal antifuses
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2000
DOI: 10.1109/55.843155
The time-dependent development of electric double-layers in saline solutions
Publisher: IOP Publishing
Date: 17-02-2006
DC magnetron glow discharge amorphous silicon
Publisher: Elsevier BV
Date: 10-1984
Fizeau interferometer system for fast high resolution studies of spectral line shapes
Publisher: AIP Publishing
Date: 02-2011
DOI: 10.1063/1.3525102
Abstract: A monochromator/Fizeau interferometer/intensified CCD camera system is described that was developed for the measurement of the shape of spectral lines that are rapidly time varying. The most important operating parameter that determines the performance of the instrument is the size of the entrance aperture as this determines both the light throughput and the effective interferometer wavelength resolution. This paper discusses, both theoretically and experimentally, the effect of the finite source area on the instrumental resolution to assist in optimizing the choice of this parameter. A second effect that often produces a practical limit to the quality of the spectra is drift of the interferometer plates. Measurements of the shapes of spectral lines of ions and atoms ejected from the cathode spot of continuous and pulsed cathodic arcs are presented to demonstrate the utility of this instrument.
Compressive stress induced formation of cubic boron nitride
Publisher: Elsevier BV
Date: 04-1993
Electron spin resonance study of amorphous hydrogenated carbon films
Publisher: Elsevier BV
Date: 10-1983
Mental Health Following Acquisition of Disability in Adulthood—The Impact of Wealth
Publisher: Public Library of Science (PLoS)
Date: 07-10-2015
Oriented graphite layer formation in Ti/C and TiC/C multilayers deposited by high current pulsed cathodic arc
Publisher: AIP Publishing
Date: 10-2008
DOI: 10.1063/1.2959835
Abstract: Ti/C and TiC/C multilayers with periods ranging from 2 to 18 nm were grown by filtered high current pulsed cathodic arc. The growth was monitored in situ by ellipsometry and cantilever stress measurements. The ellipsometry results reveal that the optical properties of the carbon vary as a function of thickness. Correspondingly, the stress in each carbon layer as measured in situ exhibits two well defined values: initially the stress is low and then takes on a higher value for the remainder of the layer. Transmission electron microscopy shows that the initial growth of carbon on Ti or TiC layer is oriented with graphitic basal planes aligned parallel to the interface. After 2–4 nm of growth, the graphitic structure transforms to amorphous carbon. Electron energy loss spectroscopy shows that the carbon layer simultaneously undergoes a transition from sp2 rich to sp3 rich material.
Electronic structure of phosphorus and arsenicδ
Publisher: American Physical Society (APS)
Date: 06-09-2013
Electric field assisted ion exchange of silver in soda-lime glass: A study of ion depletion layers and interactions with potassium
Publisher: AIP Publishing
Date: 05-2019
DOI: 10.1063/1.5092545
Abstract: The introduction of silver ions into glass by diffusion from an external source is of interest in modifying the optical and electrical properties of glass for device applications. Silver is introduced to fabricate in-glass waveguides, while potassium ions are introduced to pattern the silver diffusion by locally impeding the diffusion. Electric fields assist the silver diffusion, leading to faster diffusion rates of ions and allowing greater concentrations of silver without a metallic cluster formation. However, ion depletion layers are formed in the glass as a result of the application of electric field. Here, we study the nature of these depletion layers using depth profiles of composition after electric field diffusion, using cross-sectional energy dispersive x-ray spectroscopy analysis and infrared spectroscopy (Fourier transform infrared attenuated total reflection spectroscopy). We confirm the accelerated diffusion of silver by an electric field and show that potassium impedes the diffusion of silver even when a field is present. We find that an ion depletion layer is formed below the glass surface by the applied electric field which leads to a thermal relaxation and depolarization process when the s les are reheated. Observation of this process enables activation energies and threshold temperatures for the diffusion of Ag, K, and Na to be evaluated and compared with values obtained by composition profiles. Potassium was found to increase the initially low temperature threshold for silver diffusion, increase the activation energy, and also impede sodium diffusion.
The effect of phase difference between powered electrodes on RF plasmas
Publisher: IOP Publishing
Date: 10-05-2005
Selective absorber design
Publisher: Elsevier BV
Date: 07-1980
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