ORCID Profile
0000-0001-6504-0503
Current Organisations
Politecnico di Torino
,
La Trobe University
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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)
Electrical and Electronic Engineering | Structural Biology (incl. Macromolecular Modelling) | Biological Physics | Nanotechnology | Photonics, Optoelectronics and Optical Communications | Photonics and Electro-Optical Engineering (excl. Communications) | Biochemistry and Cell Biology | Condensed Matter Physics | Microelectronics and Integrated Circuits | Synchrotrons; Accelerators; Instruments and Techniques | Proteins and Peptides | Nanometrology | Nanotechnology | Signal Transduction | Nanoscale Characterisation | Functional materials | Photonics optoelectronics and optical communications | Nanomanufacturing | Nanoscale characterisation | Proteomics and Intermolecular Interactions (excl. Medical Proteomics) | Other Physical Sciences | Functional Materials | Surfaces and Structural Properties of Condensed Matter | Nonlinear Optics and Spectroscopy | Electronic and Magnetic Properties of Condensed Matter; Superconductivity | Condensed Matter Imaging
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in the Biological Sciences | Expanding Knowledge in Technology | Manufacturing not elsewhere classified | Expanding Knowledge in the Medical and Health Sciences | Resourcing of Education and Training Systems | Expanding Knowledge in the Chemical Sciences | Medical Instruments | Scientific Instruments | Integrated Circuits and Devices |
Related Links
Publications
3D lattice distortions and defect structures in ion-implanted nano-crystals
Publisher: Springer Science and Business Media LLC
Date: 06-04-2017
DOI: 10.1038/SREP45993
Abstract: Focussed Ion Beam (FIB) milling is a mainstay of nano-scale machining. By manipulating a tightly focussed beam of energetic ions, often gallium (Ga + ), FIB can sculpt nanostructures via localised sputtering. This ability to cut solid matter on the nano-scale revolutionised s le preparation across the life, earth and materials sciences. Despite its widespread usage, detailed understanding of the FIB-induced structural damage, intrinsic to the technique, remains elusive. Here we examine the defects caused by FIB in initially pristine objects. Using Bragg Coherent X-ray Diffraction Imaging (BCDI), we are able to spatially-resolve the full lattice strain tensor in FIB-milled gold nano-crystals. We find that every use of FIB causes large lattice distortions. Even very low ion doses, typical of FIB imaging and previously thought negligible, have a dramatic effect. Our results are consistent with a damage microstructure dominated by vacancies, highlighting the importance of free-surfaces in determining which defects are retained. At larger ion fluences, used during FIB-milling, we observe an extended dislocation network that causes stresses far beyond the bulk tensile strength of gold. These observations provide new fundamental insight into the nature of the damage created and the defects that lead to a surprisingly inhomogeneous morphology.
Strain tomography of polycrystalline zirconia dental prostheses by synchrotron X-ray diffraction
Publisher: Elsevier BV
Date: 04-2011
Diffraction imaging: The limits of partial coherence
Publisher: American Physical Society (APS)
Date: 03-12-2012
An in-vacuum x-ray diffraction microscope for use in the 0.7-2.9 keV range
Publisher: AIP Publishing
Date: 03-2012
DOI: 10.1063/1.3688655
Abstract: A dedicated in-vacuum coherent x-ray diffraction microscope was installed at the 2-ID-B beamline of the Advanced Photon Source for use with 0.7–2.9 keV x-rays. The instrument can accommodate three common implementations of diffractive imaging plane wave illumination defocused-probe (Fresnel diffractive imaging) and scanning (ptychography) using either a pinhole, focused or defocused probe. The microscope design includes active feedback to limit motion of the optics with respect to the s le. Upper bounds on the relative optics-to-s le displacement have been measured to be 5.8 nm(v) and 4.4 nm(h) rms/h using capacitance micrometry and 27 nm/h using x-ray point projection imaging. The stability of the measurement platform and in-vacuum operation allows for long exposure times, high signal-to-noise and large dynamic range two-dimensional intensity measurements to be acquired. Finally, we illustrate the microscope's stability with a recent experimental result.
Simultaneous X-ray fluorescence and scanning X-ray diffraction microscopy at the Australian Synchrotron XFM beamline
Publisher: International Union of Crystallography (IUCr)
Date: 11-08-2016
DOI: 10.1107/S1600577516011917
Abstract: Owing to its extreme sensitivity, quantitative mapping of elemental distributions via X-ray fluorescence microscopy (XFM) has become a key microanalytical technique. The recent realisation of scanning X-ray diffraction microscopy (SXDM) meanwhile provides an avenue for quantitative super-resolved ultra-structural visualization. The similarity of their experimental geometries indicates excellent prospects for simultaneous acquisition. Here, in both step- and fly-scanning modes, robust, simultaneous XFM-SXDM is demonstrated.
Optical ptychographic microscopy for quantitative anisotropic phase imaging
Publisher: SPIE
Date: 09-12-2016
DOI: 10.1117/12.2242942
Imaging shock wave dynamics at the nanometer scale with an X-ray free electron laser
Publisher: OSA
Date: 2016
Observations of phase changes in monoolein during high viscous injection
Publisher: International Union of Crystallography (IUCr)
Date: 21-03-2022
DOI: 10.1107/S1600577522001862
Abstract: Serial crystallography of membrane proteins often employs high-viscosity injectors (HVIs) to deliver micrometre-sized crystals to the X-ray beam. Typically, the carrier medium is a lipidic cubic phase (LCP) media, which can also be used to nucleate and grow the crystals. However, despite the fact that the LCP is widely used with HVIs, the potential impact of the injection process on the LCP structure has not been reported and hence is not yet well understood. The self-assembled structure of the LCP can be affected by pressure, dehydration and temperature changes, all of which occur during continuous flow injection. These changes to the LCP structure may in turn impact the results of X-ray diffraction measurements from membrane protein crystals. To investigate the influence of HVIs on the structure of the LCP we conducted a study of the phase changes in monoolein/water and monoolein/buffer mixtures during continuous flow injection, at both atmospheric pressure and under vacuum. The reservoir pressure in the HVI was tracked to determine if there is any correlation with the phase behaviour of the LCP. The results indicated that, even though the reservoir pressure underwent (at times) significant variation, this did not appear to correlate with observed phase changes in the s le stream or correspond to shifts in the LCP lattice parameter. During vacuum injection, there was a three-way coexistence of the gyroid cubic phase, diamond cubic phase and lamellar phase. During injection at atmospheric pressure, the coexistence of a cubic phase and lamellar phase in the monoolein/water mixtures was also observed. The degree to which the lamellar phase is formed was found to be strongly dependent on the co-flowing gas conditions used to stabilize the LCP stream. A combination of laboratory-based optical polarization microscopy and simulation studies was used to investigate these observations.
Roadmap on Label-Free Super-Resolution Imaging
Publisher: Wiley
Date: 30-10-2023
A review of recent in situ deformation studies using synchrotron X-ray (Micro) beams
Publisher: Bentham Science Publishers Ltd.
Date: 05-2012
Evaluation of serial crystallographic structure determination within megahertz pulse trains
Publisher: AIP Publishing
Date: 11-2019
DOI: 10.1063/1.5124387
Abstract: The new European X-ray Free-Electron Laser (European XFEL) is the first X-ray free-electron laser capable of delivering intense X-ray pulses with a megahertz interpulse spacing in a wavelength range suitable for atomic resolution structure determination. An outstanding but crucial question is whether the use of a pulse repetition rate nearly four orders of magnitude higher than previously possible results in unwanted structural changes due to either radiation damage or systematic effects on data quality. Here, separate structures from the first and subsequent pulses in the European XFEL pulse train were determined, showing that there is essentially no difference between structures determined from different pulses under currently available operating conditions at the European XFEL.
Imaging of grain-level orientation and strain in thicker metallic polycrystals by high energy transmission micro-beam Laue (HETL) diffraction techniques
Publisher: Walter de Gruyter GmbH
Date: 02-2012
DOI: 10.3139/146.110660
Abstract: For high performance, safety-critical applications, such as aerospace components, in-depth understanding of the material's response to complex loading conditions is essential. Moreover, it is vital to know how the material behaviour may be modified as a consequence of fatigue loading and how its eventual failure occurs. Unlike bulk properties, such as stiffness, yield stress, etc. that depend on the average response of the grains in a polycrystal, material failure is determined by “weakest link” type mechanisms. These depend strongly on grain-level deformation behaviour and grain-to-grain interactions. Micro-beam Laue diffraction is a powerful tool to probe these phenomena. However, the classical setup is limited to the study of s le surface regions or thin sections, due to the limited penetration into the s le at photon energies of 5 – 25 keV. A much more useful tool for the material scientist and engineer would allow the probing of grain-level orientation and stress in thicker sections of engineering components. To this end, we have developed the high energy transmission Laue (HETL) technique, an extension of the micro-beam Laue technique to significantly higher photon energies (50 – 150 keV). For the imaging of lattice orientation and elastic strain in three dimensions, we propose two alternative approaches: Laue orientation tomography (LOT) and high energy differential aperture X-ray microscopy (HEDAXM). In this paper an overview of the recent progress in HETL, LOT and HEDAXM measurements will be given and some first results illustrating the potential of these techniques presented.
A universal measure for coherence requirements in diffractive imaging
Publisher: SPIE
Date: 26-09-2013
DOI: 10.1117/12.2027269
Nanoscale probing of cholesterol-rich domains in single bilayer dimyristoyl-phosphocholine membranes using near-field spectroscopic imaging
Publisher: American Chemical Society (ACS)
Date: 27-10-2020
Protein crystal screening and characterization for serial femtosecond nanocrystallography
Publisher: Springer Science and Business Media LLC
Date: 03-05-2016
DOI: 10.1038/SREP25345
Abstract: The recent development of X-ray free electron lasers (XFELs) has spurred the development of serial femtosecond nanocrystallography (SFX) which, for the first time, is enabling structure retrieval from sub-micron protein crystals. Although there are already a growing number of structures published using SFX, the technology is still very new and presents a number of unique challenges as well as opportunities for structural biologists. One of the biggest barriers to the success of SFX experiments is the preparation and selection of suitable protein crystal s les. Here we outline a protocol for preparing and screening for suitable XFEL targets.
High-energy transmission Laue micro-beam X-ray diffraction: A probe for intra-granular lattice orientation and elastic strain in thicker samples
Publisher: International Union of Crystallography (IUCr)
Date: 16-03-2012
Rapid microfluidic mixing and liquid jets for studying biomolecular chemical dynamics
Publisher: SPIE
Date: 02-01-2017
DOI: 10.1117/12.2283381
A peak-finding algorithm based on robust statistical analysis in serial crystallography
Publisher: International Union of Crystallography (IUCr)
Date: 03-11-2017
DOI: 10.1107/S1600576717014340
Abstract: The recent development of serial crystallography at synchrotron and X-ray free-electron laser (XFEL) sources is producing crystallographic datasets of ever increasing volume. The size of these datasets is such that fast and efficient analysis presents a range of challenges that have to be overcome to enable real-time data analysis, which is essential for the effective management of XFEL experiments. Among the blocks which constitute the analysis pipeline, one major bottleneck is `peak finding', whose goal is to identify the Bragg peaks within (often) noisy diffraction patterns. Development of faster and more reliable peak-finding algorithms will allow for efficient processing and storage of the incoming data, as well as the optimal use of diffraction data for structure determination. This paper addresses the problem of peak finding and, by extension, `hit finding' in crystallographic XFEL datasets, by exploiting recent developments in robust statistical analysis. The approach described here involves two basic steps: (1) the identification of pixels which contain potential peaks and (2) modeling of the local background in the vicinity of these potential peaks. The presented framework can be generalized to include both complex background models and alternative models for the Bragg peaks.
On-chip photonic Fourier transform with surface plasmon polaritons
Publisher: Springer Science and Business Media LLC
Date: 26-02-2016
DOI: 10.1038/LSA.2016.34
Abstract: The Fourier transform (FT), a cornerstone of optical processing, enables rapid evaluation of fundamental mathematical operations, such as derivatives and integrals. Conventionally, a converging lens performs an optical FT in free space when light passes through it. The speed of the transformation is limited by the thickness and the focal length of the lens. By using the wave nature of surface plasmon polaritons (SPPs), here we demonstrate that the FT can be implemented in a planar configuration with a minimal propagation distance of around 10 μm, resulting in an increase of speed by four to five orders of magnitude. The photonic FT was tested by synthesizing intricate SPP waves with their Fourier components. The reduced dimensionality in the minuscule device allows the future development of an ultrafast on-chip photonic information processing platform for large-scale optical computing.
Analysis of multi-hit crystals in serial synchrotron crystallography experiments using high-viscosity injectors
Publisher: MDPI AG
Date: 09-01-2021
Abstract: Serial Synchrotron Crystallography (SSX) is rapidly emerging as a promising technique for collecting data for time-resolved structural studies or for performing room temperature micro-crystallography measurements using micro-focused beamlines. SSX is often performed using high frame rate detectors in combination with continuous s le scanning or high-viscosity or liquid jet injectors. When performed using ultra-bright X-ray Free Electron Laser (XFEL) sources serial crystallography typically involves a process known as ’diffract-and-destroy’ where each crystal is measured just once before it is destroyed by the intense XFEL pulse. In SSX, however, particularly when using high-viscosity injectors (HVIs) such as Lipidico, the crystal can be intercepted multiple times by the X-ray beam prior to exiting the interaction region. This has a number of important consequences for SSX including whether these multiple-hits can be incorporated into the data analysis or whether they need to be excluded due to the potential impact of radiation damage. Here, we investigate the occurrence and characteristics of multiple hits on single crystals using SSX with lipidico. SSX data are collected from crystals as they tumble within a high viscous stream of silicone grease flowing through a micro-focused X-ray beam. We confirmed that, using the Eiger 16M, we are able to collect up to 42 frames of data from the same single crystal prior to it leaving the X-ray interaction region. The frequency and occurrence of multiple hits may be controlled by varying the s le flow rate and X-ray beam size. Calculations of the absorbed dose confirm that these crystals are likely to undergo radiation damage but that nonetheless incorporating multiple hits into damage-free data should lead to a significant reduction in the number of crystals required for structural analysis when compared to just looking at a single diffraction pattern from each crystal.
Erratum: X-ray micro-beam characterization of lattice rotations and distortions due to an individual dislocation
Publisher: Springer Science and Business Media LLC
Date: 31-01-2014
DOI: 10.1038/NCOMMS4253
The soft x-ray instrument for materials studies at the linac coherent light source x-ray free-electron laser
Publisher: AIP Publishing
Date: 04-2012
DOI: 10.1063/1.3698294
Abstract: The soft x-ray materials science instrument is the second operational beamline at the linac coherent light source x-ray free electron laser. The instrument operates with a photon energy range of 480–2000 eV and features a grating monochromator as well as bendable refocusing mirrors. A broad range of experimental stations may be installed to study erse scientific topics such as: ultrafast chemistry, surface science, highly correlated electron systems, matter under extreme conditions, and laboratory astrophysics. Preliminary commissioning results are presented including the first soft x-ray single-shot energy spectrum from a free electron laser.
Data reduction for serial crystallography using a robust peak finder
Publisher: International Union of Crystallography (IUCr)
Date: 13-09-2021
DOI: 10.1107/S1600576721007317
Abstract: A peak-finding algorithm for serial crystallography (SX) data analysis based on the principle of `robust statistics' has been developed. Methods which are statistically robust are generally more insensitive to any departures from model assumptions and are particularly effective when analysing mixtures of probability distributions. For ex le, these methods enable the discretization of data into a group comprising inliers ( i.e. the background noise) and another group comprising outliers ( i.e. Bragg peaks). Our robust statistics algorithm has two key advantages, which are demonstrated through testing using multiple SX data sets. First, it is relatively insensitive to the exact value of the input parameters and hence requires minimal optimization. This is critical for the algorithm to be able to run unsupervised, allowing for automated selection or `vetoing' of SX diffraction data. Secondly, the processing of in idual diffraction patterns can be easily parallelized. This means that it can analyse data from multiple detector modules simultaneously, making it ideally suited to real-time data processing. These characteristics mean that the robust peak finder (RPF) algorithm will be particularly beneficial for the new class of MHz X-ray free-electron laser sources, which generate large amounts of data in a short period of time.
Reconstruction of axisymmetric strain distributions via neutron strain tomography
Publisher: Elsevier BV
Date: 2012
Optical barcoding using polarisation sensitive plasmonic biosensors for the detection of self-assembled monolayers
Publisher: Springer Science and Business Media LLC
Date: 29-07-2022
DOI: 10.1038/S41598-022-16804-0
Abstract: Periodic subwavelength apertures have the ability to passively detect variations in the dielectric properties of the local s le environment through modification of the plasmon resonances associated with these structures. The resulting resonance peak can effectively provide a ‘fingerprint’ indicative of the dielectric properties of the medium within the near-surface region. Here we report on the use of bimodal silver-based plasmonic colour filters for molecular sensing. Firstly, by exploring the optical output of these devices as a function of the incident polarisation for a range of different analytes of known refractive index, we were able to both maximise and quantify their sensitivity. We then apply this concept to the real-time monitoring of the formation of self-assembled monolayers based on detection of the optical output using a spectrometer. This highlights the potential for bimodal plasmonic devices to be able to dynamically monitor variations in the local environment down to the level of single molecules without the need for specific functionalisation or labelling. Advantages of using this technique include the ability for these devices to be miniaturised and to dynamically tailor their optical output permitting the analysis of very small s le volumes and maximise their dynamic range for a specific analyte.
Phase-diverse Fresnel coherent diffractive imaging of malaria parasite-infected red blood cells in the water window
Publisher: The Optical Society
Date: 18-12-2013
DOI: 10.1364/OE.21.032151
Elemental contrast imaging with a polychromatic laboratory x-ray source using energy-discriminating detectors
Publisher: SPIE
Date: 24-11-2016
DOI: 10.1117/12.2243011
Characterisation of residual stress due to fillet rolling on bolts made of a nickel base superalloy
Publisher: Trans Tech Publications, Ltd.
Date: 08-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.996.670
Abstract: This paper investigates residual stress due to fillet rolling on bolts made of ATI 718Plus® superalloy. Incremental hole drilling, neutron diffraction and neutron transmission have been used to assess residual stress near the bolt head fillet. A compressive residual stress field was identified in the first 0.5 mm from the surface. Post fillet rolling solution anneal can relieve the residual stress at the fillet.
Application and validity of the Radon transform applied to axisymmetric neutron strain imaging
Publisher: Elsevier BV
Date: 12-2019
Competition between strain-induced and temperature-controlled nucleation of InAs/GaAs quantum dots
Publisher: AIP Publishing
Date: 02-03-2004
DOI: 10.1063/1.1645637
Abstract: Atomic force microscopy and photoluminescence spectroscopy (PL) have been used to study asymmetric bilayer InAs quantum dot (QD) structures grown by molecular-beam epitaxy on GaAs(001) substrates. The two QD layers were separated by a GaAs spacer layer (SL) of varying thickness and were grown at different substrate temperatures. Grown independently, these two layers would exhibit a widely different QD number density, and this technique therefore enables us to assess the influence of the strain fields created by the dots in the first layer on the second-layer QD nucleation and characteristics. For very large SLs (& nm), total strain relief causes the QD nucleation to be controlled exclusively by the substrate temperature, which influences the migration of In adatoms. In this case, the optical and morphological properties of the second QD layer are identical to a structure with a single QD layer grown at the same temperature. In structures with a much smaller SL, strain effects dominate over the effect of temperature in controlling the nucleation of the QDs, thereby fixing the second-layer QD number density to that of the first (templating effect). There is also evidence that strain relaxation is present in the QDs of the second layer and that this is crucial for extending their emission wavelength. The optimum SL thickness is shown to be 11 nm, for which low-temperature PL emission peaks at 1.26 μm, with a full width at half-maximum of only 15 meV. Intermediate SL thicknesses exhibit broad QD size distributions, with strain effects only partly influencing the QD growth in the second layer.
Neutron strain tomography using Bragg-edge transmission
Publisher: Walter de Gruyter GmbH
Date: 02-2012
DOI: 10.3139/146.110674
Abstract: Predicting the fatigue lifetime of components relies on a knowledge of the residual elastic strain present throughout the bulk of the material. Non-destructively mapping the complete strain distribution throughout large volumes presents significant practical challenges. Recently a technique known as Bragg-edge neutron transmission has been developed as a means of non-destructive bulk elastic strain evaluation. Whilst conventional radiography measures the integral absorption, Bragg-edge neutron transmission probes the average strain along the incident beam direction. A “strain radiogram” is thus a two-dimensional average projection of the strain within the s le. Here we demonstrate how strain radiograms can be used for “neutron strain tomography” and we present and contrast two different approaches to the problem of characterising spatially resolved elastic strains.
High-tech composites to ancient metals
Publisher: Elsevier BV
Date: 07-2009
A review of automated sleep disorder detection
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.COMPBIOMED.2022.106100
Abstract: Automated sleep disorder detection is challenging because physiological symptoms can vary widely. These variations make it difficult to create effective sleep disorder detection models which support hu-man experts during diagnosis and treatment monitoring. From 2010 to 2021, authors of 95 scientific papers have taken up the challenge of automating sleep disorder detection. This paper provides an expert review of this work. We investigated whether digital technology and Artificial Intelligence (AI) can provide automated diagnosis support for sleep disorders. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines during the content discovery phase. We compared the performance of proposed sleep disorder detection methods, involving differ-ent datasets or signals. During the review, we found eight sleep disorders, of which sleep apnea and insomnia were the most studied. These disorders can be diagnosed using several kinds of biomedical signals, such as Electrocardiogram (ECG), Polysomnography (PSG), Electroencephalogram (EEG), Electromyogram (EMG), and snore sound. Subsequently, we established areas of commonality and distinctiveness. Common to all reviewed papers was that AI models were trained and tested with labelled physiological signals. Looking deeper, we discovered that 24 distinct algorithms were used for the detection task. The nature of these algorithms evolved, before 2017 only traditional Machine Learning (ML) was used. From 2018 onward, both ML and Deep Learning (DL) methods were used for sleep disorder detection. The strong emergence of DL algorithms has considerable implications for future detection systems because these algorithms demand significantly more data for training and testing when compared with ML. Based on our review results, we suggest that both type and amount of labelled data is crucial for the design of future sleep disorder detection systems because this will steer the choice of AI algorithm which establishes the desired decision support. As a guiding principle, more labelled data will help to represent the variations in symptoms. DL algorithms can extract information from these larger data quantities more effectively, therefore we predict that the role of these algorithms will continue to expand.
Partial coherence and the influence of overlap and curvature in ptychography
Publisher: SPIE
Date: 02-01-2017
DOI: 10.1117/12.2283395
Large-Scale Fabrication of Optically Active Plasmonic Arrays via Displacement Talbot Lithography
Publisher: IOP Publishing
Date: 02-2020
DOI: 10.1088/1742-6596/1455/1/012005
Abstract: Periodic nanoapertures fabricated in thin metal films exhibit a range of interesting properties in the presence of electromagnetic waves including phenomena such as extraordinary optical transmission (EOT). Fundamentally, these effects are mediated by plasmons and have been shown to have a vast range of applications, including, colour filtering, chemical sensing, and as components in solar cells. In the majority of cases, the high spatial resolution required for precise fabrication of these structures is limited to direct writing techniques such as Focused Ion Beam (FIB) and Electron beam lithography (EBL), which only cover relatively small, micron-sized, areas. In this article, we describe and demonstrate the fabrication of plasmonically active devices in the visible range using Displacement Talbot Lithography (DTL). This method allows nanometre-resolution photolithography to be performed over very large areas (whole wafers) without any significant degradation in quality. We present experimental results for a range of different structures including periodic, aperiodic and hexagonal configurations in silver films.
Synchrotron X-ray analysis of microstructure and microdeformation in a recast AA6063 aluminium alloy
Publisher: SAGE Publications
Date: 28-12-2010
Abstract: Aluminium alloy AA6063 has been processed by re-casting to produce polycrystalline ingots containing large grains. The microstructure and deformation behaviour of this material was studied by different techniques, including scanning electron microscopy, synchrotron X-ray micro-tomography, and synchrotron X-ray diffraction. The relationship between the dislocation cell-wall structure and reciprocal space maps obtained by diffraction was explored with the help of a dislocation model. The combination of different methods provides improved insight into the relationship between microstructure and deformation.
Analysis of the internal structure and lattice (mis)orientation in individual grains of deformed CP nickel polycrystals by synchrotron X-ray micro-diffraction and microscopy
Publisher: Elsevier BV
Date: 09-2012
RICH TOMOGRAPHY TECHNIQUES FOR THE ANALYSIS OF MICROSTRUCTURE AND DEFORMATION
Publisher: World Scientific Pub Co Pte Lt
Date: 06-2014
DOI: 10.1142/S0219876213430068
Abstract: Until very recently, the three-dimensionality of the material world presented numerous challenges in terms of characterization, data handling, visualization, and modeling. For this reason, 2D representation of sections, projections, or surfaces remained the mainstay of most popular imaging techniques, such as optical and electron microscopy and X-ray radiography. However, the advent of faster computers with greater memory capacity ensured that large 3D matrices can now not only be stored and manipulated efficiently, but also that advanced algorithms such as algebraic reconstruction techniques (ART) can be used to interpret redundant datasets containing multiple projections or averages across the object obtained by some suitable analytical measurement technique. These tools open up unprecedented opportunities for numerical simulation. Model formulation can be accomplished semi-automatically on the basis of microstructurally-informed 3D imaging, while model validation can be achieved by direct comparison of 3D maps of complex quantities, such as displacement vectors or strain tensor components. In this paper, we review several modalities of what can be referred to as "rich" tomography: strain tomography in the bulk of a load bearing structural component Laue orientation tomography for nondestructive mapping of grain orientation within a polycrystal, and the use of sequences of tomographic reconstructions for digital volume correlation (DVC) analysis of in situ deformation.
Bimodal Plasmonic Color Filters Enable Direct Optical Imaging of Ion Implantation in Thin Films
Publisher: Wiley
Date: 04-02-2022
Abstract: Optical metamaterials offer precise control over the properties and interactions of light at the nanoscale, attracting interest in many new fields of research including chemical and molecular sensing, magnetic antennas, and photovoltaic elements. By utilizing the phenomenon of extraordinary optical transmission (EOT) plasmonic devices enable the detection of minute changes in the local, near‐surface, dielectric properties of materials, opening up a wide range of different applications. Characterization of the optoelectronic properties of ultra‐thin films is of paramount importance for a wide range of electronic applications including integrated circuit production. However, it is often extremely difficult to achieve using conventional imaging techniques. Here, it is demonstrated that plasmonic color filters can be used for the direct optical imaging and characterization of ion implantation in thin films. A model system consisting of variable doses of gallium ions implanted within titanium oxide thin films is used. It is observed that the ion implantation dose leads to a variation in the measured plasmon resonance spectra, which can be further enhanced through the use of bimodal nanopixel arrays. Using Monte Carlo simulations and the Maxwell‐Garnett relation, the observed plasmon resonance spectra in terms of the gallium ion implantation dose is quantitatively interpreted.
Ptychographic imaging of NaD1 induced yeast cell death
Publisher: The Optical Society
Date: 06-09-0026
Microfluidic mixing and jetting devices based on SU8 and glass for time-resolved molecular imaging experiments
Publisher: SPIE
Date: 04-03-2019
DOI: 10.1117/12.2508437
Evaluation of the overload effect on fatigue crack growth with the help of synchrotron XRD strain mapping
Publisher: Elsevier BV
Date: 11-2010
Investigation of the effect of helium ion (He+) irradiation on the fluorescence properties of microdiamonds grown by chemical vapour deposition
Publisher: Oxford University Press (OUP)
Date: 30-07-2021
Energy-resolved neutron imaging options at a small angle neutron scattering instrument at the Australian Center for Neutron Scattering
Publisher: AIP Publishing
Date: 03-2019
DOI: 10.1063/1.5081909
Abstract: Energy-resolved neutron imaging experiments conducted on the Small Angle Neutron Scattering (SANS) instrument, Bilby, demonstrate how the capabilities of this instrument can be enhanced by a relatively simple addition of a compact neutron counting detector. Together with possible SANS s le surveying and location of the region of interest, this instrument is attractive for many imaging applications. In particular, the combination of the cold spectrum of the neutron beam and its pulsed nature enables unique non-destructive studies of the internal structure for s les that are opaque to other more traditional techniques. In addition to conventional white beam neutron radiography, we conducted energy-resolved imaging experiments capable of resolving features related to microstructure in crystalline materials with a spatial resolution down to ∼0.1 mm. The optimized settings for the beamline configuration were determined for the imaging modality, where the compromise between the beam intensity and the achievable spatial resolution is of key concern.
Nanocrystallography measurements of early stage synthetic malaria pigment
Publisher: International Union of Crystallography (IUCr)
Date: 28-09-2017
DOI: 10.1107/S1600576717012663
Abstract: The recent availability of extremely intense, femtosecond X-ray free-electron laser (XFEL) sources has spurred the development of serial femtosecond nanocrystallography (SFX). Here, SFX is used to analyze nanoscale crystals of β-hematin, the synthetic form of hemozoin which is a waste by-product of the malaria parasite. This analysis reveals significant differences in β-hematin data collected during SFX and synchrotron crystallography experiments. To interpret these differences two possibilities are considered: structural differences between the nanocrystal and larger crystalline forms of β-hematin, and radiation damage. Simulation studies show that structural inhomogeneity appears at present to provide a better fit to the experimental data. If confirmed, these observations will have implications for designing compounds that inhibit hemozoin formation and suggest that, for some systems at least, additional information may be gained by comparing structures obtained from nanocrystals and macroscopic crystals of the same molecule.
Local regularization of tilt projections reduces artifacts in electron tomography
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.JSB.2014.03.009
Abstract: Electron tomography produces very high resolution 3D image volumes useful for investigating the structure and function of cellular components. Unfortunately, unavoidable discontinuities and physical constraints in the acquisition geometry lead to a range of artifacts that can affect the reconstructed image. In particular, highly electron dense regions, such as gold nanoparticles, can hide proximal biological structures and degrade the overall quality of the reconstructed tomograms. In this work we introduce a pre-reconstruction non-conservative non-linear isotropic diffusion (NID) filter that automatically identifies and reduces local irregularities in the tilt projections. We illustrate the improvement in quality obtained using this approach for reconstructed tomograms generated from s les of malaria parasite-infected red blood cells. A quantitative and qualitative evaluation for our approach on both simulated and real data is provided.
Sub-Millisecond Integrated Mix-and-Inject Microfluidic Sample Delivery Devices
Publisher: MDPI AG
Date: 08-02-2021
DOI: 10.20944/PREPRINTS202102.0199.V1
Abstract: Microfluidic devices which integrate both rapid mixing and liquid jetting for s le delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for s le delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.
Fresnel coherent diffraction tomography
Publisher: The Optical Society
Date: 19-05-2010
DOI: 10.1364/OE.18.011746
Measurements of long-range electronic correlations during femtosecond diffraction experiments performed on nanocrystals of buckminsterfullerene
Publisher: MyJove Corporation
Date: 22-08-2017
DOI: 10.3791/56296
Whole-cell phase contrast imaging at the nanoscale using Fresnel Coherent Diffractive Imaging Tomography
Publisher: Springer Science and Business Media LLC
Date: 26-07-2013
DOI: 10.1038/SREP02288
Radiation damage in a micron-sized protein crystal studied via reciprocal space mapping and Bragg coherent diffractive imaging
Publisher: AIP Publishing
Date: 29-04-2015
DOI: 10.1063/1.4919641
Abstract: For laboratory and synchrotron based X-ray sources, radiation damage has posed a significant barrier to obtaining high-resolution structural data from biological macromolecules. The problem is particularly acute for micron-sized crystals where the weaker signal often necessitates the use of higher intensity beams to obtain the relevant data. Here, we employ a combination of techniques, including Bragg coherent diffractive imaging to characterise the radiation induced damage in a micron-sized protein crystal over time. The approach we adopt here could help screen for potential protein crystal candidates for measurement at X-ray free election laser sources.
Lab-based x-ray tomography of a cochlear implant using energy discriminating detectors for metal artefact reduction
Publisher: SPIE
Date: 02-01-2017
DOI: 10.1117/12.2283320
Polarisation and rheology characterisation of monoolein/water liquid crystal dynamical behaviour during high-viscosity injector extrusion
Publisher: Elsevier BV
Date: 2024
A phenomenological model of the X-ray pulse statistics of a high-repetition-rate X-ray free-electron laser.
Publisher: International Union of Crystallography (IUCr)
Date: 03-10-2023
Polycrystal deformation analysis by high energy synchrotron X-ray diffraction on the I12 JEEP beamline at Diamond Light Source
Publisher: Elsevier BV
Date: 08-2010
Temporal cross-correlation of x-ray free electron and optical lasers using soft x-ray pulse induced transient reflectivity
Publisher: The Optical Society
Date: 03-05-2012
DOI: 10.1364/OE.20.011396
Simultaneous X-ray diffraction, crystallography and fluorescence mapping using the Maia detector
Publisher: Elsevier BV
Date: 02-2018
High resolution imaging and analysis of residual elastic strain in an additively manufactured turbine blade
Publisher: Inderscience Publishers
Date: 2017
Imaging Lattice dynamics in individual nanocrystals
Publisher: OSA
Date: 2014
Megahertz pulse trains enable multi-hit serial femtosecond crystallography experiments at X-ray free electron lasers
Publisher: Springer Science and Business Media LLC
Date: 11-08-2022
DOI: 10.1038/S41467-022-32434-6
Abstract: The European X-ray Free Electron Laser (XFEL) and Linac Coherent Light Source (LCLS) II are extremely intense sources of X-rays capable of generating Serial Femtosecond Crystallography (SFX) data at megahertz (MHz) repetition rates. Previous work has shown that it is possible to use consecutive X-ray pulses to collect diffraction patterns from in idual crystals. Here, we exploit the MHz pulse structure of the European XFEL to obtain two complete datasets from the same lysozyme crystal, first hit and the second hit, before it exits the beam. The two datasets, separated by µs, yield up to 2.1 Å resolution structures. Comparisons between the two structures reveal no indications of radiation damage or significant changes within the active site, consistent with the calculated dose estimates. This demonstrates MHz SFX can be used as a tool for tracking sub-microsecond structural changes in in idual single crystals, a technique we refer to as multi-hit SFX.
Coherence properties of individual femtosecond pulses of an x-ray free-electron laser
Publisher: American Physical Society (APS)
Date: 30-09-2011
Recent Advances and Future Perspectives on Microfluidic Mix-and-Jet Sample Delivery Devices
Publisher: MDPI AG
Date: 07-05-2021
DOI: 10.3390/MI12050531
Abstract: The integration of the Gas Dynamic Virtual Nozzle (GDVN) and microfluidic technologies has proven to be a promising s le delivery solution for biomolecular imaging studies and has the potential to be transformative for a range of applications in physics, biology, and chemistry. Here, we review the recent advances in the emerging field of microfluidic mix-and-jet s le delivery devices for the study of biomolecular reaction dynamics. First, we introduce the key parameters and dimensionless numbers involved in their design and characterisation. Then we critically review the techniques used to fabricate these integrated devices and discuss their advantages and disadvantages. We then summarise the most common experimental methods used for the characterisation of both the mixing and jetting components. Finally, we discuss future perspectives on the emerging field of microfluidic mix-and-jet s le delivery devices. In summary, this review aims to introduce this exciting new topic to the wider microfluidics community and to help guide future research in the field.
Mapping the dislocation sub-structure of deformed polycrystalline Ni by scanning microbeam diffraction topography
Publisher: Elsevier BV
Date: 05-2011
Using coherent X-ray ptychography to probe medium-range order
Publisher: The Optical Society
Date: 07-11-2013
DOI: 10.1364/OE.21.028019
Strengthening mechanisms in an Al-Fe-Cr-Ti nano-quasicrystalline alloy and composites
Publisher: Elsevier BV
Date: 08-2016
Feasibility study of neutron strain tomography
Publisher: Elsevier BV
Date: 07-2009
Probing intra-granular deformation by micro-beam Laue diffraction
Publisher: Elsevier BV
Date: 07-2009
Visualization and measurement of the local absorption coefficients of single bilayer phospholipid membranes using scanning near-field optical microscopy
Publisher: The Optical Society
Date: 27-11-2019
Stability, flow alignment and a phase transition of the lipidic cubic phase during continuous flow injection
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.JCIS.2021.12.110
Abstract: Continuous flow injection is a key technology for serial crystallography measurements of protein crystals suspended in the lipidic cubic phase (LCP). To date, there has been little discussion in the literature regarding the impact of the injection process itself on the structure of the lipidic phase. This is despite the fact that the phase of the injection matrix is critical for the flow properties of the stream and potentially for s le stability. Here we report small-angle X-ray scattering measurements of a monoolein:water mixture during continuous delivery using a high viscosity injector. We observe both an alignment and modification of the LCP as a direct result of the injection process. The orientation of the cubic lattice with respect to the beam was estimated based on the anisotropy of the diffraction pattern and does not correspond to a single low order zone axis. The solvent fraction was also observed to impact the stability of the cubic phase during injection. In addition, depending on the distance traveled by the lipid after exiting the needle, the phase is observed to transition from a pure diamond phase (Pn3m) to a mixture containing both gyriod (Ia3d) and lamellar (L
Nanoscale mapping of the three-dimensional deformation field within commercial nanodiamonds
Publisher: Inderscience Publishers
Date: 2017
Electron-beam induced diamond-like-carbon passivation of plasmonic devices
Publisher: SPIE
Date: 22-12-2015
DOI: 10.1117/12.2202567
Lensless imaging using broadband X-ray sources
Publisher: Springer Science and Business Media LLC
Date: 26-06-2011
The serial millisecond crystallography instrument at the Australian Synchrotron incorporating the “Lipidico” injector
Publisher: AIP Publishing
Date: 08-2019
DOI: 10.1063/1.5104298
Abstract: A serial millisecond crystallography (SMX) facility has recently been implemented at the macromolecular crystallography beamline, MX2 at the Australian Synchrotron. The setup utilizes a combination of an EIGER X 16M detector system and an in-house developed high-viscosity injector, “Lipidico.” Lipidico uses a syringe needle to extrude the microcrystal-containing viscous media and it is compatible with commercially available syringes. The combination of s le delivery via protein crystals suspended in a viscous mixture and a millisecond frame rate detector enables high-throughput serial crystallography at the Australian Synchrotron. A hit-finding algorithm, based on the principles of “robust-statistics,” is employed to rapidly process the data. Here we present the first SMX experimental results with a detector frame rate of 100 Hz (10 ms exposures) and the Lipidico injector using a mixture of lysozyme microcrystals embedded in high vacuum silicon grease. Details of the experimental setup, s le injector, and data analysis pipeline are designed and developed as part of the Australian Synchrotron SMX instrument and are reviewed here.
Structure-film thickness relationship study of sputtered NiO/Ni bilayers using depth profiling and atomic force microscopy techniques
Publisher: AIP Publishing
Date: 15-06-2006
DOI: 10.1063/1.2205556
Abstract: Ni O ∕ Ni thin film bilayers have been grown on Si (100) substrates using low temperature dc reactive magnetron sputtering. The s les were grown under identical process conditions but with different amounts of NiO deposited in order to determine film quality as a function of thickness. In order to investigate the structural properties of the NiO overlayers a synchrotron detector has been developed to make energy-resolved electron yield x-ray absorption spectroscopy measurements at ambient pressure. From these studies we have been able to construct a complete depth profile of the NiO∕Ni bilayers and, by modeling of the electron multiplication ropagation processes within the films, extract quantitative information about them. In combination with atomic force microscopy measurements we have determined that there exists a clear variation in the structural and morphological properties of the NiO thin films as a function of thickness. The densest overlayers with the most conformal surface are observed for film thicknesses & nm and & nm. We rationalize these results in terms of the underlying morphology of the Ni film and the effects of misfit strain between the layers.
Ultrafast three-dimensional imaging of lattice dynamics in individual gold nanocrystals
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-07-2013
Abstract: Nanoparticles have found many applications in modern technology however, the full characterization of in idual particles is challenging. One of the most interesting mechanical properties is the particle's response to lattice distortion. This property has been probed for ensembles of nanoparticles, but the required averaging may distort the results. Clark et al. (p. 56 , published online 23 May see the Perspective by Hartland and Lo ) were able to image the generation and subsequent evolution of coherent acoustic phonons from an in idual perturbed gold nanocrystal on the picosecond time scale.
Mixing and jetting analysis using continuous flow microfluidic sample delivery devices
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0RA00232A
Abstract: Design schematics of microfluidic mix- and-jet devices for serial femtosecond crystallography (SFX) at X-ray free electron lasers (XFELs).
Rapid, low dose X-ray diffractive imaging of the malaria parasite Plasmodium falciparum
Publisher: Elsevier BV
Date: 08-2014
DOI: 10.1016/J.ULTRAMIC.2013.09.003
Abstract: Phase- erse X-ray coherent diffractive imaging (CDI) provides a route to high sensitivity and spatial resolution with moderate radiation dose. It also provides a robust solution to the well-known phase-problem, making on-line image reconstruction feasible. Here we apply phase- erse CDI to a cellular s le, obtaining images of an erythrocyte infected by the sexual stage of the malaria parasite, Plasmodium falciparum, with a radiation dose significantly lower than the lowest dose previously reported for cellular imaging using CDI. The high sensitivity and resolution allow key biological features to be identified within intact cells, providing complementary information to optical and electron microscopy. This high throughput method could be used for fast tomographic imaging, or to generate multiple replicates in two-dimensions of hydrated biological systems without freezing or fixing. This work demonstrates that phase- erse CDI is a valuable complementary imaging method for the biological sciences and ready for immediate application.
Keyhole coherent diffractive imaging
Publisher: Springer Science and Business Media LLC
Date: 09-03-2008
DOI: 10.1038/NPHYS896
Propagation‐based X‐ray phase‐contrast tomography of mastectomy samples using synchrotron radiation
Publisher: Wiley
Date: 20-10-2019
DOI: 10.1002/MP.13842
Abstract: Propagation-based phase-contrast computed tomography (PB-CT) is a method for three-dimensional x-ray imaging that utilizes refraction, as well as absorption, of x rays in the tissues to increase the signal-to-noise ratio (SNR) in the resultant images, in comparison with equivalent conventional absorption-only x-ray tomography (CT). Importantly, the higher SNR is achieved without sacrificing spatial resolution or increasing the radiation dose delivered to the imaged tissues. The present work has been carried out in the context of the current development of a breast CT imaging facility at the Australian Synchrotron. Seven unfixed complete mastectomy s les with and without breast cancer lesions have been imaged using absorption-only CT and PB-CT techniques under controlled experimental conditions. The radiation doses delivered to the mastectomy s les during the scans were comparable to those approved for mammographic screening. Physical characteristics of the reconstructed images, such as spatial resolution and SNR, have been measured and compared with the results of the radiological quality assessment of the complete absorption CT and PB-CT image stacks. Despite the presence of some image artefacts, the PB-CT images have outperformed comparable absorption CT images collected at the same radiation dose, in terms of both the measured objective image characteristics and the radiological image scores. The outcomes of these experiments are shown to be consistent with predictions of the theory of PB-CT imaging and previous reported experimental studies of this imaging modality. The results presented in this paper demonstrate that PB-CT holds a high potential for improving on the quality and diagnostic value of images obtained using existing medical x-ray technologies, such as mammography and digital breast tomosynthesis (DBT). If implemented at suitable synchrotron imaging facilities, PB-CT can be used to complement existing imaging modalities, leading to more accurate breast cancer diagnosis.
Brain tumor detection and screening using artificial intelligence techniques: Current trends and future perspectives
Publisher: Elsevier BV
Date: 09-2023
Multiple wavelength diffractive imaging
Publisher: American Physical Society (APS)
Date: 06-02-2009
Three-dimensional reconstruction of the size and shape of protein microcrystals using Bragg coherent diffractive imaging
Publisher: IOP Publishing
Date: 14-03-2016
Micro-beam Laue alignment of multi-reflection Bragg coherent diffraction imaging measurements
Publisher: International Union of Crystallography (IUCr)
Date: 08-08-2017
DOI: 10.1107/S1600577517009183
Abstract: Multi-reflection Bragg coherent diffraction imaging has the potential to allow three-dimensional (3D) resolved measurements of the full lattice strain tensor in specific micro-crystals. Until now such measurements were h ered by the need for laborious, time-intensive alignment procedures. Here a different approach is demonstrated, using micro-beam Laue X-ray diffraction to first determine the lattice orientation of the micro-crystal. This information is then used to rapidly align coherent diffraction measurements of three or more reflections from the crystal. Based on these, 3D strain and stress fields in the crystal are successfully determined. This approach is demonstrated on a focused ion beam milled micro-crystal from which six reflections could be measured. Since information from more than three independent reflections is available, the reliability of the phases retrieved from the coherent diffraction data can be assessed. Our results show that rapid, reliable 3D coherent diffraction measurements of the full lattice strain tensor in specific micro-crystals are now feasible and can be successfully carried out even in heavily distorted s les.
Imaging transient melting of a nanocrystal using an X-ray laser
Publisher: Proceedings of the National Academy of Sciences
Date: 06-2015
Abstract: Despite phase transitions, such as melting, being ubiquitous in nature, understanding what occurs at the nanoscale (such as in nanocrystals) has so far remained challenging. With ensemble studies of nanocrystals it is often difficult to discriminate between intrinsic size-dependent properties and effects due to s le size and shape dispersity. Here, using an X-ray free electron laser we image the reversible melting of an in idual nanocrystal induced by an ultrashort laser. It is revealed that the melting occurs transiently, repeatably, and inhomogeneously. This is consistent with a core-shell model where the exterior is melted and a solid core remains. These findings reveal, unambiguously, that core-shell melting occurs, which has important implications for understanding nanoscale phenomena.
Preferred orientation and its effects on intensity-correlation measurements
Publisher: International Union of Crystallography (IUCr)
Date: 21-01-2022
DOI: 10.1107/S2052252521012422
Abstract: Intensity-correlation measurements allow access to nanostructural information on a range of ordered and disordered materials beyond traditional pair-correlation methods. In real space, this information can be expressed in terms of a pair-angle distribution function (PADF) which encodes three- and four-body distances and angles. To date, correlation-based techniques have not been applied to the analysis of microstructural effects, such as preferred orientation, which are typically investigated by texture analysis. Preferred orientation is regarded as a potential source of error in intensity-correlation experiments and complicates interpretation of the results. Here, the theory of preferred orientation in intensity-correlation techniques is developed, connecting it to the established theory of texture analysis. The preferred-orientation effect is found to scale with the number of crystalline domains in the beam, surpassing the nanostructural signal when the number of domains becomes large. Experimental demonstrations are presented of the orientation-dominant and nanostructure-dominant cases using PADF analysis. The results show that even minor deviations from uniform orientation produce the strongest angular correlation signals when the number of crystalline domains in the beam is large.
Towards real-time analysis of liquid jet alignment in serial femtosecond crystallography
Publisher: International Union of Crystallography (IUCr)
Date: 08-2022
DOI: 10.1107/S1600576722005891
Abstract: Liquid s le delivery systems are used extensively for serial femtosecond crystallography at X-ray free-electron lasers (XFELs). However, misalignment of the liquid jet and the XFEL beam leads to the X-rays either partially or completely missing the s le, resulting in s le wastage and a loss of experiment time. Implemented here is an algorithm to analyse optical images using machine vision to determine whether there is overlap of the X-ray beam and liquid jet. The long-term goal is to use the output from this algorithm to implement an automated feedback mechanism to maintain constant alignment of the X-ray beam and liquid jet. The key elements of this jet alignment algorithm are discussed and its performance is characterized by comparing the results with a manual analysis of the optical image data. The success rate of the algorithm for correctly identifying hits is quantified via a similarity metric, the Dice coefficient. In total four different nozzle designs were used in this study, yielding an overall Dice coefficient of 0.98.
High-resolution X-ray imaging of Plasmodium falciparum-infected red blood cells
Publisher: Wiley
Date: 10-2008
DOI: 10.1002/CYTO.A.20616
Abstract: Methods for imaging cellular architecture and ultimately macromolecular complexes and in idual proteins, within a cellular environment, are an important goal for cell and molecular biology. Coherent diffractive imaging (CDI) is a method of lensless imaging that can be applied to any in idual finite object. A diffraction pattern from a single biological structure is recorded and an iterative Fourier transform between real space and reciprocal space is used to reconstruct information about the architecture of the s le to high resolution. As a test system for cellular imaging, we have applied CDI to an important human pathogen, the malaria parasite, Plasmodium falciparum. We have employed a novel CDI approach, known as Fresnel CDI, which uses illumination with a curved incident wavefront, to image red blood cells infected with malaria parasites. We have examined the intrinsic X-ray absorption contrast of these cells and compared them with cells contrasted with heavy metal stains or immunogold labeling. We compare CDI images with data obtained from the same cells using scanning electron microscopy, light microscopy, and scanning X-ray fluorescence microscopy. We show that CDI can offer new information both within and at the surface of complex biological specimens at a spatial resolution of better than 40 nm. and we demonstrate an imaging modality that conveniently combines scanning X-ray fluorescence microscopy with CDI. The data provide independent confirmation of the validity of the coherent diffractive image and demonstrate that CDI offers the potential to become an important and reliable new high-resolution imaging modality for cell biology. CDI can detect features at high resolution within unsectioned cells.
Local Structural Damage Evaluation of a C/C-SiC Ceramic Matrix Composite
Publisher: Oxford University Press (OUP)
Date: 24-04-2017
DOI: 10.1017/S1431927617000459
Abstract: Ceramic matrix composites (CMCs) are structural materials, which have useful properties that combine high strength at high temperatures with moderate toughness. Carbon fibers within a matrix of carbon and silicon carbide, called C/C–SiC, are a particular class of CMC noted for their high oxidation resistance. Here we use a combination of four-point bending and X-ray radiography, to study the mechanical failure of C/C-SiC CMCs. Correlating X-ray radiographic and load/displacement curve data reveals that the fiber bundles act to slow down crack propagation during four-point bending tests. We attribute this to the fact that strain energy is expended in breaking these fibers and in pulling fiber bundles out of the surrounding matrix material. In addition, we find that the local distribution and concentration of SiC plays an important role in reducing the toughness of the material.
Bragg coherent diffraction imaging and metrics for radiation damage in protein micro-crystallography
Publisher: International Union of Crystallography (IUCr)
Date: 2017
DOI: 10.1107/S1600577516017525
Abstract: The proliferation of extremely intense synchrotron sources has enabled ever higher-resolution structures to be obtained using data collected from smaller and often more imperfect biological crystals (Helliwell, 1984). Synchrotron beamlines now exist that are capable of measuring data from single crystals that are just a few micrometres in size. This provides renewed motivation to study and understand the radiation damage behaviour of small protein crystals. Reciprocal-space mapping and Bragg coherent diffractive imaging experiments have been performed on cryo-cooled microcrystals of hen egg-white lysozyme as they undergo radiation damage. Several well established metrics, such as intensity-loss and lattice expansion, are applied to the diffraction data and the results are compared with several new metrics that can be extracted from the coherent imaging experiments. In idually some of these metrics are inconclusive. However, combining metrics, the results suggest that radiation damage behaviour in protein micro-crystals differs from that of larger protein crystals and may allow them to continue to diffract for longer. A possible mechanism to account for these observations is proposed.
Ross filter pairs for metal artefact reduction in x-ray tomography: A case study based on imaging and segmentation of metallic implants
Publisher: SPIE
Date: 02-01-2017
DOI: 10.1117/12.2282937
Broadband chirality-coded meta-aperture for photon-spin resolving
Publisher: Springer Science and Business Media LLC
Date: 02-12-2015
DOI: 10.1038/NCOMMS10051
Abstract: The behaviour of light transmitted through an in idual subwavelength aperture becomes counterintuitive in the presence of surrounding ‘decoration’, a phenomenon known as the extraordinary optical transmission. Despite being polarization-sensitive, such an in idual nano-aperture, however, often cannot differentiate between the two distinct spin-states of photons because of the loss of photon information on light-aperture interaction. This creates a ‘blind-spot’ for the aperture with respect to the helicity of chiral light. Here we report the development of a subwavelength aperture embedded with metasurfaces dubbed a ‘meta-aperture’, which breaks this spin degeneracy. By exploiting the phase-shaping capabilities of metasurfaces, we are able to create specific meta-apertures in which the pair of circularly polarized light spin-states produces opposite transmission spectra over a broad spectral range. The concept incorporating metasurfaces with nano-apertures provides a venue for exploring new physics on spin-aperture interaction and potentially has a broad range of applications in spin-optoelectronics and chiral sensing.
Strain-interactions between InAs/GaAs quantum dot layers
Publisher: Elsevier BV
Date: 10-2004
Diffraction data from aerosolized Coliphage PR772 virus particles imaged with the Linac Coherent Light Source
Publisher: Springer Science and Business Media LLC
Date: 19-11-2020
DOI: 10.1038/S41597-020-00745-2
Abstract: Single Particle Imaging (SPI) with intense coherent X-ray pulses from X-ray free-electron lasers (XFELs) has the potential to produce molecular structures without the need for crystallization or freezing. Here we present a dataset of 285,944 diffraction patterns from aerosolized Coliphage PR772 virus particles injected into the femtosecond X-ray pulses of the Linac Coherent Light Source (LCLS). Additional exposures with background information are also deposited. The diffraction data were collected at the Atomic, Molecular and Optical Science Instrument (AMO) of the LCLS in 4 experimental beam times during a period of four years. The photon energy was either 1.2 or 1.7 keV and the pulse energy was between 2 and 4 mJ in a focal spot of about 1.3 μ m x 1.7 μ m full width at half maximum (FWHM). The X-ray laser pulses captured the particles in random orientations. The data offer insight into aerosolised virus particles in the gas phase, contain information relevant to improving experimental parameters, and provide a basis for developing algorithms for image analysis and reconstruction.
Elemental Contrast X-ray Tomography Using Ross Filter Pairs with a Polychromatic Laboratory Source
Publisher: Springer Science and Business Media LLC
Date: 16-03-2017
DOI: 10.1038/S41598-017-00304-7
Abstract: The majority of current laboratory based X-ray sources are polychromatic and are not tuneable. This lack of monochromaticity limits the range of applications for these sources and in particular it reduces the elemental specificity of laboratory based X-ray imaging experiments. Here we present a solution to this problem based on the use of Ross filter pairs. Although such Ross filter arrangements have been applied in proof-of-principle spectroscopy experiments, to date there have been no reports of this approach used for full-field X-ray imaging. Here we report on the experimental demonstration of Ross filter pairs being used for quasi-monochromatic, full-field imaging. This arrangement has several important benefits for laboratory based X-ray imaging including, as we demonstrate, elemental contrast enhancement. The method is demonstrated both for two-dimensional radiography and for three-dimensional X-ray tomography.
Broadband X-ray ptychography
Publisher: AIP Publishing LLC
Date: 2016
DOI: 10.1063/1.4937542
Quantitative coherent diffractive imaging of an integrated circuit at a spatial resolution of 20 nm
Publisher: AIP Publishing
Date: 24-11-2008
DOI: 10.1063/1.3025819
Abstract: The complex transmission function of an integrated circuit is reconstructed at 20 nm spatial resolution using coherent diffractive imaging. A quantitative map is made of the exit surface wave emerging from void defects within the circuit interconnect. Assuming a known index of refraction for the substrate allows the volume of these voids to be estimated from the phase retardation in this region. S le scanning and tomography of extended objects using coherent diffractive imaging is demonstrated.
High energy transmission micro-beam Laue synchrotron X-ray diffraction
Publisher: Elsevier BV
Date: 06-1970
From grain boundaries to single defects: A review of coherent methods for materials imaging in the X-ray sciences
Publisher: Springer Science and Business Media LLC
Date: 06-08-2013
Mapping of domain structure in Barium Titanate single crystals by synchrotron x-ray topography
Publisher: SPIE
Date: 25-03-2010
DOI: 10.1117/12.845837
Synchrotron X-ray tomographic investigation of internal structure of individual flax fibres
Publisher: Springer Berlin Heidelberg
Date: 2010
Megahertz serial crystallography
Publisher: Springer Science and Business Media LLC
Date: 02-10-2018
DOI: 10.1038/S41467-018-06156-7
Abstract: The new European X-ray Free-Electron Laser is the first X-ray free-electron laser capable of delivering X-ray pulses with a megahertz inter-pulse spacing, more than four orders of magnitude higher than previously possible. However, to date, it has been unclear whether it would indeed be possible to measure high-quality diffraction data at megahertz pulse repetition rates. Here, we show that high-quality structures can indeed be obtained using currently available operating conditions at the European XFEL. We present two complete data sets, one from the well-known model system lysozyme and the other from a so far unknown complex of a β-lactamase from K. pneumoniae involved in antibiotic resistance. This result opens up megahertz serial femtosecond crystallography (SFX) as a tool for reliable structure determination, substrate screening and the efficient measurement of the evolution and dynamics of molecular structures using megahertz repetition rate pulses available at this new class of X-ray laser source.
Monte Carlo study of variations in the surface sensitivity of energy-resolved x-ray absorption spectra from Ni/NiO thin-film bilayers
Publisher: American Physical Society (APS)
Date: 07-12-2006
Ptychographic fresnel coherent diffractive imaging
Publisher: American Physical Society (APS)
Date: 08-12-2009
Nanoscale Fresnel Coherent diffraction imaging tomography using ptychography
Publisher: The Optical Society
Date: 12-10-2012
DOI: 10.1364/OE.20.024678
The influence of photoelectron escape in radiation damage simulations of protein micro-crystallography
Publisher: MDPI AG
Date: 27-06-2018
DOI: 10.3390/CRYST8070267
Abstract: Radiation damage represents a fundamental limit in the determination of protein structures via macromolecular crystallography (MX) at third-generation synchrotron sources. Over the past decade, improvements in both source and detector technology have led to MX experiments being performed with smaller and smaller crystals (on the order of a few microns), often using microfocus beams. Under these conditions, photoelectrons (PEs), the primary agents of radiation-damage in MX, may escape the diffraction volume prior to depositing all of their energy. The impact of PE escape is more significant at higher beam energies ( keV) as the electron inelastic mean free path (IMFP) is longer, allowing the electrons to deposit their energy over a larger area, extending further from their point of origin. Software such as RADDOSE-3D has been used extensively to predict the dose (energy absorbed per unit mass) that a crystal will absorb under a given set of experimental parameters and is an important component in planning a successful MX experiment. At the time this study was undertaken, dose predictions made using RADDOSE-3D were spatially-resolved, but did not yet account for the propagation of PEs through the diffraction volume. Hence, in the case of microfocus crystallography, it is anticipated that deviations may occur between the predicted and actual dose absorbed due to the influence of PEs. To explore this effect, we conducted a series of simulations of the dose absorbed by micron-sized crystals during microfocus MX experiments. Our simulations spanned beam and crystal sizes ranging from 1μm to 5μm for beam energies between 9 keV and 30 keV. Our simulations were spatially and temporarily resolved and accounted for the escape of PEs from the diffraction volume. The spatially-resolved dose maps produced by these simulations were used to predict the rate of intensity loss in a Bragg spot, a key metric for tracking global radiation damage. Our results were compared to predictions obtained using a recent version of RADDOSE-3D that did not account for PE escape the predicted crystal lifetimes are shown to differ significantly for the smallest crystals and for high-energy beams, when PE escape is included in the simulations.
Plasmon-induced enhancement of ptychographic phase microscopy via sub-surface nanoaperture arrays
Publisher: Springer Science and Business Media LLC
Date: 25-01-2021
Colorimetric histology using plasmonically active microscope slides
Publisher: Springer Science and Business Media LLC
Date: 06-10-2021
Partial coherence: A route to performing faster coherent diffraction imaging
Publisher: IOP Publishing
Date: 25-10-2013
Genomic and Phenotypic Biomarkers for Precision Medicine Guidance in Advanced Prostate Cancer
Publisher: Springer Science and Business Media LLC
Date: 10-08-2023
DOI: 10.1007/S11864-023-01121-Z
Abstract: Prostate cancer (PCa) is the second most diagnosed malignant neoplasm and is one of the leading causes of cancer-related death in men worldwide. Despite significant advances in screening and treatment of PCa, given the heterogeneity of this disease, optimal personalized therapeutic strategies remain limited. However, emerging predictive and prognostic biomarkers based on in idual patient profiles in combination with computer-assisted diagnostics have the potential to guide precision medicine, where patients may benefit from therapeutic approaches optimally suited to their disease. Also, the integration of genotypic and phenotypic diagnostic methods is supporting better informed treatment decisions. Focusing on advanced PCa, this review discusses polygenic risk scores for screening of PCa and common genomic aberrations in androgen receptor (AR), PTEN-PI3K-AKT, and DNA damage response (DDR) pathways, considering clinical implications for diagnosis, prognosis, and treatment prediction. Furthermore, we evaluate liquid biopsy, protein biomarkers such as serum testosterone levels, SLFN11 expression, total alkaline phosphatase (tALP), neutrophil-to-lymphocyte ratio (NLR), tissue biopsy, and advanced imaging tools, summarizing current phenotypic biomarkers and envisaging more effective utilization of diagnostic and prognostic biomarkers in advanced PCa. We conclude that prognostic and treatment predictive biomarker discovery can improve the management of patients, especially in metastatic stages of advanced PCa. This will result in decreased mortality and enhanced quality of life and help design a personalized treatment regimen.
X-ray micro-beam characterization of lattice rotations and distortions due to an individual dislocation
Publisher: Springer Science and Business Media LLC
Date: 12-11-2013
DOI: 10.1038/NCOMMS3774
Abstract: Understanding and controlling the behaviour of dislocations is crucial for a wide range of applications, from nano-electronics and solar cells to structural engineering alloys. Quantitative X-ray diffraction measurements of the strain fields due to in idual dislocations, particularly in the bulk, however, have thus far remained elusive. Here we report the first characterization of a single dislocation in a freestanding GaAs/In0.2Ga0.8As/GaAs membrane by synchrotron X-ray micro-beam Laue diffraction. Our experimental X-ray data agrees closely with textbook anisotropic elasticity solutions for dislocations, providing one of few experimental validations of this fundamental theory. On the basis of the experimental uncertainty in our measurements, we predict the X-ray beam size required for three-dimensional measurements of lattice strains and rotations due to in idual dislocations in the material bulk. These findings have important implications for the in situ study of dislocation structure formation, self-organization and evolution in the bulk.
Polycrystalline materials analysis using the Maia pixelated energy-dispersive X-ray area detector
Publisher: Cambridge University Press (CUP)
Date: 26-09-2017
DOI: 10.1017/S0885715617000768
Abstract: Elemental, chemical, and structural analysis of polycrystalline materials at the micron scale is frequently carried out using microfocused synchrotron X-ray beams, sometimes on multiple instruments. The Maia pixelated energy-dispersive X-ray area detector enables the simultaneous collection of X-ray fluorescence (XRF) and diffraction because of the relatively large solid angle and number of pixels when compared with other systems. The large solid angle also permits extraction of surface topography because of changes in self-absorption. This work demonstrates the capability of the Maia detector for simultaneous measurement of XRF and diffraction for mapping the short- and long-range order across the grain structure in a Ni polycrystalline foil.
MyD88 TIR domain higher-order assembly interactions revealed by microcrystal electron diffraction and serial femtosecond crystallography
Publisher: Springer Science and Business Media LLC
Date: 10-05-2021
DOI: 10.1038/S41467-021-22590-6
Abstract: MyD88 and MAL are Toll-like receptor (TLR) adaptors that signal to induce pro-inflammatory cytokine production. We previously observed that the TIR domain of MAL (MAL TIR ) forms filaments in vitro and induces formation of crystalline higher-order assemblies of the MyD88 TIR domain (MyD88 TIR ). These crystals are too small for conventional X-ray crystallography, but are ideally suited to structure determination by microcrystal electron diffraction (MicroED) and serial femtosecond crystallography (SFX). Here, we present MicroED and SFX structures of the MyD88 TIR assembly, which reveal a two-stranded higher-order assembly arrangement of TIR domains analogous to that seen previously for MAL TIR . We demonstrate via mutagenesis that the MyD88 TIR assembly interfaces are critical for TLR4 signaling in vivo, and we show that MAL promotes unidirectional assembly of MyD88 TIR . Collectively, our studies provide structural and mechanistic insight into TLR signal transduction and allow a direct comparison of the MicroED and SFX techniques.
Lipidico injection protocol for serial crystallography measurements at the australian synchrotron
Publisher: MyJove Corporation
Date: 23-09-2020
DOI: 10.3791/61650
Computational simulation of the effects of interfacial tension in microfluidic flow focusing droplet generators
Publisher: Frontiers Media SA
Date: 09-02-2023
DOI: 10.3389/FPHY.2023.1060780
Abstract: We present simulations of a square flow focusing droplet generator device exploring its performance characteristics over a range of interfacial surface tension values and varying neck width. Droplet generators have a wide range of applications from drug delivery to X-ray diffraction experiments. Matching the droplet frequency and volume to the experimental parameters is critical for maximising the data quality and minimising s le waste. Whilst varying the interfacial surface tension we observed that the lowest frequency of droplets is generated for surface tensions matching those typically reported for water-oil mixtures (around 40 mN/M). Decreasing or increasing the interfacial surface tension, for ex le by adding surfactant, results in an increase in droplet frequency. We also find that under the conditions simulated here, droplets are generated with much lower capillary numbers and higher Weber numbers than have typically been reported in the literature. The high ratio of flowrate-to-cross-section used here resulted in a velocity which was larger than has previously been reported for flow focusing devices and consequently we observe particularly large associated Reynolds numbers. However, in general, the simulated flow behaviour characteristics most closely match those typically observed for the jetting and tip-streaming regimes. The highest frequency of droplets achieved in our simulated devices was 36 kHz and 56 kHz corresponding to square neck channel widths of 12.5 and 25 µm respectively, an interfacial surface tension of 118.75 mN/m. We also examined the effect of varying neck width geometry for a fixed interfacial surface tension of 52 mN/m. We observed that the highest frequency droplet generation, 61 kHz, corresponded to a neck width of 37.5 µm with a corresponding droplet diameter of 22 µm. The high frequency, high monodispersity, and small droplet size predicted to occur through modification of the interfacial surface tension will have implications for the future design and optimisation of droplet-on-demand microfluidic devices.
Fresnel coherent diffractive imaging tomography of whole cells in capillaries
Publisher: IOP Publishing
Date: 05-09-2014
Neutron Strain Tomography using the Radon Transform
Publisher: Elsevier BV
Date: 2015
A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs
Publisher: MDPI AG
Date: 10-04-2021
DOI: 10.3390/APP11083404
Abstract: Microfluidic devices which integrate both rapid mixing and liquid jetting for s le delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for s le delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.
X-ray laser–induced electron dynamics observed by femtosecond diffraction from nanocrystals of Buckminsterfullerene
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-09-2016
Abstract: Coherent electron dynamics in a periodic array of C 60 molecular targets driven by intense x-ray pulses of femtosecond duration.
Role of Four-Chamber Heart Ultrasound Images in Automatic Assessment of Fetal Heart: A Systematic Understanding
Publisher: MDPI AG
Date: 18-04-2022
DOI: 10.3390/INFORMATICS9020034
Abstract: The fetal echocardiogram is useful for monitoring and diagnosing cardiovascular diseases in the fetus in utero. Importantly, it can be used for assessing prenatal congenital heart disease, for which timely intervention can improve the unborn child’s outcomes. In this regard, artificial intelligence (AI) can be used for the automatic analysis of fetal heart ultrasound images. This study reviews nondeep and deep learning approaches for assessing the fetal heart using standard four-chamber ultrasound images. The state-of-the-art techniques in the field are described and discussed. The compendium demonstrates the capability of automatic assessment of the fetal heart using AI technology. This work can serve as a resource for research in the field.
Dual pitch plasmonic devices for polarization enhanced colour based sensing
Publisher: SPIE
Date: 09-12-2016
DOI: 10.1117/12.2242975
Optimisation of polarization controlled colour tuning using nanoscale cross-shaped apertures in silver films
Publisher: SPIE
Date: 09-12-2016
DOI: 10.1117/12.2242974
Shot-to-shot two-dimensional photon intensity diagnostics within megahertz pulse-trains at the European XFEL
Publisher: International Union of Crystallography (IUCr)
Date: 08-06-2022
DOI: 10.1107/S1600577522005720
Abstract: Characterizing the properties of X-ray free-electron laser (XFEL) sources is a critical step for optimization of performance and experiment planning. The recent availability of MHz XFELs has opened up a range of new opportunities for novel experiments but also highlighted the need for systematic measurements of the source properties. Here, MHz-enabled beam imaging diagnostics developed for the SPB/SFX instrument at the European XFEL are exploited to measure the shot-to-shot intensity statistics of X-ray pulses. The ability to record pulse-integrated two-dimensional transverse intensity measurements at multiple planes along an XFEL beamline at MHz rates yields an improved understanding of the shot-to-shot photon beam intensity variations. These variations can play a critical role, for ex le, in determining the outcome of single-particle imaging experiments and other experiments that are sensitive to the transverse profile of the incident beam. It is observed that shot-to-shot variations in the statistical properties of a recorded ensemble of radiant intensity distributions are sensitive to changes in electron beam current density. These changes typically occur during pulse-distribution to the instrument and are currently not accounted for by the existing suite of imaging diagnostics. Modulations of the electron beam orbit in the accelerator are observed to induce a time-dependence in the statistics of in idual pulses – this is demonstrated by applying radio-frequency trajectory tilts to electron bunch-trains delivered to the instrument. We discuss how these modifications of the beam trajectory might be used to modify the statistical properties of the source and potential future applications.
Ptychographic fresnel coherent diffraction tomography at the nanoscale
Publisher: Walter de Gruyter GmbH
Date: 14-07-2014
DOI: 10.3139/146.111065
Abstract: The spatial resolution of diffractive imaging techniques depends upon the numerical aperture of the detected scatter rather than any image forming optics. Fresnel coherent diffractive imaging has been developed over the past decade as a means for examining regions of interest within continuous s les and for overcoming many of the stagnation issues traditionally associated with coherent diffractive imaging. Ptychography meanwhile has been developed independently as a method of reconstructing the transmission function of extended objects from diffraction data recorded using a sequence of multiple overlapping probes on the s le. The relatively recent combination of these two methods has been found to provide substantial benefits over either of the two techniques when applied separately. The experimental requirements and basic principles of ptychographic Fresnel diffraction tomography are reviewed in this paper.
Intragranular lattice misorientation mapping by synchrotron x-ray micro-beams: Laue vs energy-resolved laue vs monochromatic reciprocal space analysis
Publisher: World Scientific Pub Co Pte Lt
Date: 20-01-2010
DOI: 10.1142/S0217979210064216
Abstract: Laue diffraction, energy scanning and reciprocal space mapping are three micro-beam synchrotron X-ray diffraction techniques allowing the investigation of local misorientation induced by the dislocation substructure. In this paper a comparison between the three methods is presented, based on the mapping of a single 311 reflection from a grain within a Ni polycrystal specimen deformed to a tensile plastic strain of ~9%. Qualitatively it is observed that the maps obtained by different techniques all share the same features, although some deviations exist due to experimental limitations associated with each of the measurement techniques.
A Direct Approach to In-Plane Stress Separation using Photoelastic Ptychography
Publisher: Springer Science and Business Media LLC
Date: 04-08-2016
DOI: 10.1038/SREP30541
Abstract: The elastic properties of materials, either under external load or in a relaxed state, influence their mechanical behaviour. Conventional optical approaches based on techniques such as photoelasticity or thermoelasticity can be used for full-field analysis of the stress distribution within a specimen. The circular polariscope in combination with holographic photoelasticity allows the sum and difference of principal stress components to be determined by exploiting the temporary birefringent properties of materials under load. Phase stepping and interferometric techniques have been proposed as a method for separating the in-plane stress components in two-dimensional photoelasticity experiments. In this paper we describe and demonstrate an alternative approach based on photoelastic ptychography which is able to obtain quantitative stress information from far fewer measurements than is required for interferometric based approaches. The complex light intensity equations based on Jones calculus for this setup are derived. We then apply this approach to the problem of a disc under diametrical compression. The experimental results are validated against the analytical solution derived by Hertz for the theoretical displacement fields for an elastic disc subject to point loading.
Continuously Tunable, Polarization Controlled, Colour Palette Produced from Nanoscale Plasmonic Pixels
Publisher: Springer Science and Business Media LLC
Date: 17-06-2016
DOI: 10.1038/SREP28062
Abstract: Colour filters based on nano-apertures in thin metallic films have been widely studied due to their extraordinary optical transmission and small size. These properties make them prime candidates for use in high-resolution colour displays and high accuracy bio-sensors. The inclusion of polarization sensitive plasmonic features in such devices allow additional control over the electromagnetic field distribution, critical for investigations of polarization induced phenomena. Here we demonstrate that cross-shaped nano-apertures can be used for polarization controlled color tuning in the visible range and apply fundamental theoretical models to interpret key features of the transmitted spectrum. Full color transmission was achieved by fine-tuning the periodicity of the apertures, whilst keeping the geometry of in idual apertures constant. We demonstrate this effect for both transverse electric and magnetic fields. Furthermore we have been able to demonstrate the same polarization sensitivity even for nano-size, sub-wavelength sets of arrays, which is paramount for ultra-high resolution compact colour displays.
Simultaneous nanostructure and chemical imaging of intact whole nematodes
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8CC09664C
Abstract: Accurately locating biologically relevant elements at high resolution: simultaneous ptychography and fluorescence imaging of large specimens comes of age.
Optical Chemical Barcoding Based on Polarization Controlled Plasmonic Nanopixels
Publisher: Wiley
Date: 04-12-2018
Soft-tissue differentiation and bone densitometry via energy-discriminating X-ray microCT
Publisher: The Optical Society
Date: 09-11-2022
DOI: 10.1364/OE.25.029328
X-ray Phase-Contrast Computed Tomography for Soft Tissue Imaging at the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron
Publisher: MDPI AG
Date: 03-04-2021
DOI: 10.3390/APP11094120
Abstract: The Imaging and Medical Beamline (IMBL) is a superconducting multipole wiggler-based beamline at the 3 GeV Australian Synchrotron operated by the Australian Nuclear Science and Technology Organisation (ANSTO). The beamline delivers hard X-rays in the 25–120 keV energy range and offers the potential for a range of biomedical X-ray applications, including radiotherapy and medical imaging experiments. One of the imaging modalities available at IMBL is propagation-based X-ray phase-contrast computed tomography (PCT). PCT produces superior results when imaging low-density materials such as soft tissue (e.g., breast mastectomies) and has the potential to be developed into a valuable medical imaging tool. We anticipate that PCT will be utilized for medical breast imaging in the near future with the advantage that it could provide better contrast than conventional X-ray absorption imaging. The unique properties of synchrotron X-ray sources such as high coherence, energy tunability, and high brightness are particularly well-suited for generating PCT data using very short exposure times on the order of less than 1 min. The coherence of synchrotron radiation allows for phase-contrast imaging with superior sensitivity to small differences in soft-tissue density. Here we also compare the results of PCT using two different detectors, as these unique source characteristics need to be complemented with a highly efficient detector. Moreover, the application of phase retrieval for PCT image reconstruction enables the use of noisier images, potentially significantly reducing the total dose received by patients during acquisition. This work is part of ongoing research into innovative tomographic methods aimed at the introduction of 3D X-ray medical imaging at the IMBL to improve the detection and diagnosis of breast cancer. Major progress in this area at the IMBL includes the characterization of a large number of mastectomy s les, both normal and cancerous, which have been scanned at clinically acceptable radiation dose levels and evaluated by expert radiologists with respect to both image quality and cancer diagnosis.
Materials Separation via the Matrix Method Employing Energy-Discriminating X-ray Detection
Publisher: MDPI AG
Date: 21-03-2022
DOI: 10.3390/APP12063198
Abstract: The majority of lab-based X-ray sources are polychromatic and are not easily tunable, which can make the 3D quantitative analysis of multi-component s les challenging. The lack of effective materials separation when using conventional X-ray tube sources has motivated the development of a number of potential solutions including the application of dual-energy X-ray computed tomography (CT) as well as the use of X-ray filters. Here, we demonstrate the simultaneous decomposition of two low-density materials via inversion of the linear attenuation matrices using data from the energy-discriminating PiXirad detector. A key application for this method is soft-tissue differentiation which is widely used in biological and medical imaging. We assess the effectiveness of this approach using both simulation and experiment noting that none of the materials investigated here incorporate any contrast enhancing agents. By exploiting the energy discriminating properties of the detector, narrow energy bands are created resulting in multiple quasi-monochromatic images being formed using a broadband polychromatic source. Optimization of the key parameters for materials separation is first demonstrated in simulation followed by experimental validation using a phantom test s le in 2D and a small-animal model in 3D.
Fluctuation X-ray diffraction reveals three-dimensional nanostructure and disorder in self-assembled lipid phases
Publisher: Springer Science and Business Media LLC
Date: 10-07-2020
DOI: 10.1038/S43246-020-0044-Z
Abstract: Emergent nanoscale order in materials such as self-assembled lipid phases, colloidal materials and metal-organic frameworks is often characterized by small-angle X-ray scattering (SAXS). Frequently, residual disorder in these materials prevents high-resolution 3D structural characterization. Here we demonstrate that angular intensity variations in SAXS patterns can provide previously inaccessible information about local 3D structure via a rich, real-space distribution of three- and four-body statistics. We present the many-body characterisation of a monoolein-based hexagonal phase doped with a phospholipid, revealing non-uniform curvature in the lipid channels, likely due to phase separation of the lipids in the membrane. Our many-body technique has general applicability to nanomaterials with order in the range 10 nm −1 μm currently targeted by synchrotron SAXS and has the potential to impact erse research areas within chemistry, biology and materials science.
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Related Funding Activities
ARC Future Fellowships - Grant ID: FT130101797
Start Date: 02-2014
End Date: 11-2018
Amount: $645,705.00
Funder: Australian Research Council
View Funded ActivityARC Centres Of Excellence - Grant ID: CE140100011
Start Date: 06-2014
End Date: 03-2021
Amount: $27,999,996.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP220103679
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End Date: 07-2025
Amount: $274,673.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE130100128
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End Date: 06-2015
Amount: $670,000.00
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View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE230100113
Start Date: 2023
End Date: 12-2023
Amount: $970,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE150100163
Start Date: 2015
End Date: 12-2016
Amount: $560,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE190100116
Start Date: 06-2019
End Date: 12-2021
Amount: $809,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE200100174
Start Date: 11-2020
End Date: 12-2022
Amount: $425,000.00
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View Funded Activity