ORCID Profile
0000-0002-2598-7193
Current Organisation
James Cook University
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Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2004
Publisher: Springer Science and Business Media LLC
Date: 30-03-2017
DOI: 10.1038/SREP45599
Abstract: Optically transparent, smooth, defect-free, chemically inert and with good adhesion to a variety of substrates, plasma polymers from plant-derived secondary metabolites have been identified as promising encapsulating materials for organic electronics and photovoltaics. Here, we demonstrate that an encapsulating layer of plasma polymerized γ-terpinene reduces degradation-related loss in conversion efficiency in PCPDTBT:PC 70 BM solar cells under ambient operating conditions. The stability of γ-terpinene films was then investigated under extreme UV irradiation conditions as a function of deposition power. When exposed to ambient air, prolonged exposure to UV–A and UV–B light led to notable ageing of the polymer. Photooxidation was identified as the main mechanism of degradation, confirmed by significantly slower ageing when oxygen was restricted through the use of a quartz cover. Under unnatural high-energy UV–C irradiation, significant photochemical degradation and oxidation occurred even in an oxygen-poor environment.
Publisher: IOP Publishing
Date: 29-01-2003
Publisher: Springer Science and Business Media LLC
Date: 12-2005
Publisher: Wiley
Date: 14-04-2010
Publisher: Elsevier BV
Date: 05-2013
Publisher: American Scientific Publishers
Date: 10-2014
Publisher: MDPI AG
Date: 30-09-2014
Publisher: MDPI AG
Date: 13-01-2017
DOI: 10.3390/NANO7010011
Publisher: Bentham Science Publishers Ltd.
Date: 22-04-2016
Publisher: Elsevier BV
Date: 03-2021
Publisher: American Chemical Society (ACS)
Date: 13-08-2015
DOI: 10.1021/ACS.NANOLETT.5B01363
Abstract: Details of a fast and sustainable bottom-up process to grow large area high quality graphene films without the aid of any catalyst are reported in this paper. We used Melaleuca alternifolia, a volatile natural extract from tea tree plant as the precursor. The as-fabricated graphene films yielded a stable contact angle of 135°, indicating their potential application in very high hydrophobic coatings. The electronic devices formed by sandwiching pentacene between graphene and aluminum films demonstrated memristive behavior, and hence, these graphene films could find use in nonvolatile memory devices also.
Publisher: Elsevier BV
Date: 10-2022
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2003
Publisher: American Chemical Society (ACS)
Date: 30-12-2016
DOI: 10.1021/ACS.CHEMREV.5B00566
Abstract: Sustainable societal and economic development relies on novel nanotechnologies that offer maximum efficiency at minimal environmental cost. Yet, it is very challenging to apply green chemistry approaches across the entire life cycle of nanotech products, from design and nanomaterial synthesis to utilization and disposal. Recently, novel, efficient methods based on nonequilibrium reactive plasma chemistries that minimize the process steps and dramatically reduce the use of expensive and hazardous reagents have been applied to low-cost natural and waste sources to produce value-added nanomaterials with a wide range of applications. This review discusses the distinctive effects of nonequilibrium reactive chemistries and how these effects can aid and advance the integration of sustainable chemistry into each stage of nanotech product life. Ex les of the use of enabling plasma-based technologies in sustainable production and degradation of nanotech products are discussed-from selection of precursors derived from natural resources and their conversion into functional building units, to methods for green synthesis of useful naturally degradable carbon-based nanomaterials, to device operation and eventual disintegration into naturally degradable yet potentially reusable byproducts.
Publisher: IEEE
Date: 2006
Publisher: Wiley
Date: 29-09-2016
Publisher: MDPI AG
Date: 25-11-2021
DOI: 10.3390/MOLECULES26237133
Abstract: Plasma polymer coatings fabricated from Melaleuca alternifolia essential oil and its derivatives have been previously shown to reduce the extent of microbial adhesion on titanium, polymers, and other implantable materials used in dentistry. Previous studies have shown these coatings to maintain their performance under standard operating conditions however, when used in e.g., a dental implant, these coatings may inadvertently become subject to in situ cleaning treatments, such as those using an atmospheric pressure plasma jet, a promising tool for the effective in situ removal of biofilms from tissues and implant surfaces. Here, we investigated the effect of such an exposure on the antimicrobial performance of the Melaleuca alternifolia polymer coating. It was found that direct exposure of the polymer coating surface to the jet for periods less than 60 s was sufficient to induce changes in its surface chemistry and topography, affecting its ability to retard subsequent microbial attachment. The exact effect of the jet exposure depended on the chemistry of the polymer coating, the length of plasma treatment, cell type, and incubation conditions. The change in the antimicrobial activity for polymer coatings fabricated at powers of 20–30 W was not statistically significant due to their limited baseline bioactivity. Interestingly, the bioactivity of polymer coatings fabricated at 10 and 15 W against Staphylococcus aureus cells was temporarily improved after the treatment, which could be attributed to the generation of loosely attached bioactive fragments on the treated surface, resulting in an increase in the dose of the bioactive agents being eluted by the surface. Attachment and proliferation of Pseudomonas aeruginosa cells and mixed cultures were less affected by changes in the bioactivity profile of the surface. The sensitivity of the cells to the change imparted by the jet treatment was also found to be dependent on their origin culture, with mature biofilm-derived P. aeruginosa bacterial cells showing a greater ability to colonize the surface when compared to its planktonic broth-grown counterpart. The presence of plasma-generated reactive oxygen and nitrogen species in the culture media was also found to enhance the bioactivity of polymer coatings fabricated at power levels of 10 and 15 W, due to a synergistic effect arising from simultaneous exposure of cells to reactive oxygen and nitrogen species (RONS) and eluted bioactive fragments. These results suggest that it is important to consider the possible implications of inadvertent changes in the properties and performance of plasma polymer coatings as a result of exposure to in situ decontamination, to both prevent suboptimal performance and to exploit possible synergies that may arise for some polymer coating-surface treatment combinations.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1MH01103K
Abstract: This review outlines recent progress and strategies for highly efficient, environmentally-friendly marine antifouling technology based on nanomaterials and nanocomposites, as well as synergistic and biomimetic approaches.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Wiley
Date: 09-2009
DOI: 10.1002/APP.30916
Publisher: Elsevier BV
Date: 11-2023
Publisher: IOP Publishing
Date: 20-07-2007
Publisher: IOP Publishing
Date: 13-01-2004
Publisher: Springer Science and Business Media LLC
Date: 17-01-2023
DOI: 10.1007/S42768-022-00120-4
Abstract: Developing applications for the by-products obtained from waste processing is vital for resource recovery. The synthesis of ZnCl 2 -activated biochar with high electrocatalytic activity was carried out by the microwave-assisted pyrolysis of pineapple peel and subsequent chemical activation process. Activated biochar is employed in the electrochemical sensing of nitrite by drop casting in a glassy carbon electrode (GCE). The activated biochar exhibited a stacked carbon sheet, 254 m 2 g −1 Brunauer, Emmett and Teller (BET) surface area, 0.076 cm 3 g −1 pore volume, 189.53 m 2 g −1 micropore area and oxygen-containing functional groups. The electrochemical impedance spectroscopy of the modified GCE showed a reduced charge transfer resistance of 61%. This is crucial to determine the electrochemical properties of biochar. The sensor showed a significant current response and an excellent limit of detection of 0.97 µmol L −1 . The modified-activated biochar electrochemical sensor demonstrated high selectivity, reproducibility (RSD=2.4%), and stability (RSD=2.6%). Graphical abstract
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2006
Publisher: Springer Science and Business Media LLC
Date: 30-03-2011
DOI: 10.1557/JMR.2011.23
Publisher: Elsevier BV
Date: 02-2017
Publisher: BMJ
Date: 12-2021
DOI: 10.1136/BMJOPEN-2021-052156
Abstract: To investigate the additional programme cost and cost-effectiveness of ‘right@home’ Nurse Home Visiting (NHV) programme in relation to improving maternal and child outcomes at child age 3 years compared with usual care. A cost–utility analysis from a government-as-payer perspective alongside a randomised trial of NHV over 3-year period. Costs and quality-adjusted life-years (QALYs) were discounted at 5%. Analysis used an intention-to-treat approach with multiple imputation. The right@home was implemented from 2013 in Victoria and Tasmania states of Australia, as a primary care service for pregnant women, delivered until child age 2 years. 722 pregnant Australian women experiencing adversity received NHV (n=363) or usual care (clinic visits) (n=359). First, a cost–consequences analysis to compare the additional costs of NHV over usual care, accounting for any reduced costs of service use, and impacts on all maternal and child outcomes assessed at 3 years. Second, cost–utility analysis from a government-as-payer perspective compared additional costs to maternal QALYs to express cost-effectiveness in terms of additional cost per additional QALY gained. When compared with usual care at child age 3 years, the right@home intervention cost $A7685 extra per woman (95% CI $A7006 to $A8364) and generated 0.01 more QALYs (95% CI −0.01 to 0.02). The probability of right@home being cost-effective by child age 3 years is less than 20%, at a willingness-to-pay threshold of $A50 000 per QALY. Benefits of NHV to parenting at 2 years and maternal health and well-being at 3 years translate into marginal maternal QALY gains. Like previous cost-effectiveness results for NHV programmes, right@home is not cost-effective at 3 years. Given the relatively high up-front costs of NHV, long-term follow-up is needed to assess the accrual of health and economic benefits over time. ISRCTN89962120 .
Publisher: Elsevier BV
Date: 07-2006
Publisher: Springer Science and Business Media LLC
Date: 12-04-2019
DOI: 10.1038/S41598-019-42211-Z
Abstract: Nanocomposites offer attractive and cost-effective thin layers with superior properties for antimicrobial, drug delivery and microelectronic applications. This work reports single-step plasma-enabled synthesis of polymer/zinc nanocomposite thin films via co-deposition of renewable geranium essential oil-derived polymer and zinc nanoparticles produced by thermal decomposition of zinc acetylacetonate. The chemical composition, surfaces characteristics and antimicrobial performance of the designed nanocomposite were systematically investigated. XPS survey proved the presence of ZnO in the matrix of formed polymers at 10 W and 50 W. SEM images verified that the average size of a ZnO nanoparticle slightly increased with an increase in the power of deposition, from approximately 60 nm at 10 W to approximately 80 nm at 50 W. Confocal scanning laser microscopy images showed that viability of S. aureus and E.coli cells significantly reduced on surfaces of ZnO olymer composites compared to pristine polymers. SEM observations further demonstrated that bacterial cells incubated on Zn/Ge 10 W and Zn/Ge 50 W had deteriorated cell walls, compared to pristine polymers and glass control. The release of ZnO nanoparticles from the composite thin films was confirmed using ICP measurements, and can be further controlled by coating the film with a thin polymeric layer. These eco-friendly nanocomposite films could be employed as encapsulation coatings to protect relevant surfaces of medical devices from microbial adhesion and colonization.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1TA10608B
Abstract: Radio frequency (RF) plasma polymerization of plant extracts offers an effective large scale encapsulation method for organic photovoltaics (OPVs).
Publisher: Elsevier BV
Date: 07-2022
Publisher: IEEE
Date: 12-2007
Publisher: Informa UK Limited
Date: 2014
Publisher: Springer Science and Business Media LLC
Date: 2003
Publisher: IEEE
Date: 2005
Publisher: Wiley
Date: 07-01-2015
DOI: 10.1002/APP.41866
Publisher: Elsevier BV
Date: 10-2006
Publisher: Elsevier BV
Date: 05-2013
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.ACTBIO.2010.12.024
Abstract: Despite many synthetic biomaterials having physical properties that are comparable or even superior to those of natural body tissues, they frequently fail due to the adverse physiological reactions they cause within the human body, such as infection and inflammation. The surface modification of biomaterials is an economical and effective method by which biocompatibility and biofunctionality can be achieved while preserving the favorable bulk characteristics of the biomaterial, such as strength and inertness. Amongst the numerous surface modification techniques available, plasma surface modification affords device manufacturers a flexible and environmentally friendly process that enables tailoring of the surface morphology, structure, composition, and properties of the material to a specific need. There are a vast range of possible applications of plasma modification in biomaterial applications, however, the focus of this review paper is on processes that can be used to develop surface morphologies and chemical structures for the prevention of adhesion and proliferation of pathogenic bacteria on the surfaces of in-dwelling medical devices. As such, the fundamental principles of bacterial cell attachment and biofilm formation are also discussed. Functional organic plasma polymerised coatings are also discussed for their potential as biosensitive interfaces, connecting inorganic/metallic electronic devices with their physiological environments.
Publisher: Springer Science and Business Media LLC
Date: 11-06-2011
Publisher: Portland Press Ltd.
Date: 11-2001
DOI: 10.1042/CS20010085
Publisher: Elsevier BV
Date: 2003
Publisher: MDPI AG
Date: 06-09-2023
DOI: 10.3390/EN16186438
Publisher: Wiley
Date: 02-05-2015
DOI: 10.1002/APP.42318
Publisher: Trans Tech Publications, Ltd.
Date: 06-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.654-656.2261
Abstract: Terpinen-4-ol is the main constituent of Melaleuca alternifolia essential oil known for its biocidal and anti-inflammatory properties. The possibility of fabricating polymer thin films from terpinen-4-ol using radio frequency (RF) plasma polymerisation for the prevention of the growth of Pseudomonas aeruginosa was investigated, and the properties of the resultant films compared against their biologically active precursor. Films fabricated at 10 W prevented bacterial attachment and EPS secretion, whilst polyterpenol films deposited at 25 W demonstrated no biocidal activity against the pathogen.
Publisher: Elsevier BV
Date: 10-2015
Publisher: IEEE
Date: 05-2007
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2001
DOI: 10.1109/22.971627
Publisher: Elsevier BV
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 04-11-2011
DOI: 10.1557/JMR.2011.349
Publisher: Elsevier BV
Date: 06-2010
Publisher: Elsevier BV
Date: 11-2013
Publisher: IEEE
Date: 11-2007
Publisher: Springer Science and Business Media LLC
Date: 12-11-2022
DOI: 10.1007/S41614-022-00102-3
Abstract: Graphene is a highly sought-after material for a wide range of applications, particularly in areas such as energy harvesting and storage, electronics, electrochemical sensors, biomedical, composites, and coatings. The synthesis of high-quality graphene is a precondition for its real-time application. However, conventional synthesis methods have certain drawbacks including laborious procedures and structural defects in graphene nanosheets. Plasma-based synthesis techniques such as plasma-enhanced chemical vapor deposition and atmospheric pressure microwave plasma are high-tech synthesis practices that can produce graphene without any solvents in a few seconds. This article reviews these state-of-the-art techniques emphasizing mainly their process parameters for the synthesis of high-grade graphene, which is defect-free, and comprises mono to few layers, great carrier mobility, and high purity. The applications of as-synthesized graphene in various fields are also provided. Moreover, the potential breakthroughs and the prospect of these techniques are also discussed in this work.
Publisher: Springer Science and Business Media LLC
Date: 09-12-2016
DOI: 10.1038/SREP38571
Abstract: This article presents low-temperature, one-step dry synthesis of optically transparent thermally-stable, biocompatible cis−β−ocimene-based thin films for applications as interlayer dielectric and encapsulating layer for flexible electronic devices, e.g. OLEDs. Morphological analysis of thin films shows uniform, very smooth ( R q 1 nm) and defect-free moderately hydrophilic surfaces. The films are optically transparent, with a refractive index of ~1.58 at 600 nm, an optical band gap of ~2.85 eV, and dielectric constant of 3.5−3.6 at 1 kHz. Upon heating, thin films are chemically and optically stable up to at least 200 °C, where thermal stability increases for films manufactured at higher RF power as well as for films deposited away from the plasma glow. Heating of the s le increases the dielectric constant, from 3.7 (25 °C) to 4.7 (120 °C) at 1 kHz for polymer fabricated at 25 W. Polymers are biocompatible with non-adherent THP–1 cells and adherent mouse macrophage cells, including LPS-stimulated macrophages, and maintain their material properties after 48 h of immersion into simulated body fluid. The versatile nature of the films fabricated in this study may be exploited in next-generation consumer electronics and energy technologies.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2002
DOI: 10.1109/22.982226
Publisher: Walter de Gruyter GmbH
Date: 07-2011
Abstract: In the fields of organic electronics and biotechnology, applications for organic polymer thin films fabricated using low-temperature non-equilibrium plasma techniques are gaining significant attention because of the physical and chemical stability of thin films and the low cost of production. Polymer thin films were fabricated from non-synthetic terpinen-4-ol using radiofrequency polymerization (13.56 MHz) on low loss dielectric substrates and their permittivity properties were ascertained to determine potential applications for these organic films. Real and imaginary parts of permittivity as a function of frequency were measured using the variable angle spectroscopic ellipsometer. The real part of permittivity (k) was found to be between 2.34 and 2.65 in the wavelength region of 400–1100 nm, indicating a potential low-k material. These permittivity values were confirmed at microwave frequencies. Dielectric properties of polyterpenol films were measured by means of split post dielectric resonators (SPDRs) operating at frequencies of 10 GHz and 20 GHz. Permittivity increased for s les deposited at higher RF energy – from 2.65 (25 W) to 2.83 (75 W) measured by a 20-GHz SPDR and from 2.32 (25 W) to 2.53 (100 W) obtained using a 10-GHz SPDR. The error in permittivity measurement was predominantly attributed to the uncertainty in film thickness measurement.
Publisher: Informa UK Limited
Date: 2007
Publisher: Elsevier BV
Date: 08-2010
Publisher: Wiley
Date: 26-09-2018
DOI: 10.1002/APP.45771
Publisher: IEEE
Date: 11-2007
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2005
Publisher: IEEE
Date: 2005
Publisher: American Scientific Publishers
Date: 10-2014
Abstract: Clinical utility of biodegradable magnesium implants is undermined by the untimely degradation of these materials in vivo. Their high corrosion rate leads to loss of mechanical integrity, peri-implant alkalization and localised accumulation of hydrogen gas. Biodegradable coatings were produced on pure magnesium using RF plasma polymerisation. A monoterpene alcohol with known anti-inflammatory and antibacterial properties was used as a polymer precursor. The addition of the polymeric layer was found to reduce the degradation rate of magnesium in simulated body fluid. The in vitro studies indicated good cytocompatibility of non-adherent THP-1 cells and mouse macrophage cells with the polymer, and the polymer coated s le. The viability of THP-1 cells was significantly improved when in contact with polymer encapsulated magnesium compared to unmodified s les. Collectively, these results suggest plasma enhanced polymer encapsulation of magnesium as a suitable method to control degradation kinetics of this biomaterial.
Publisher: Elsevier BV
Date: 04-2009
Publisher: SPIE
Date: 07-04-2004
DOI: 10.1117/12.560676
Publisher: IEEE
Date: 05-2006
Publisher: Elsevier BV
Date: 03-2012
Publisher: Wiley
Date: 2006
DOI: 10.1002/MOP.21705
Publisher: AIP Publishing
Date: 11-2005
DOI: 10.1063/1.2127124
Abstract: The effect of dopants with different valencies and ionic radii on the densification, structural ordering, and microwave dielectric properties of Ba(Mg1∕3Ta2∕3)O3 (BMT) is investigated. It is found that dopants such as Sb2O5, MnO, ZrO2, WO3, and ZnO improve the microwave dielectric properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic radii of the dopant has been established. The variation of the dielectric properties of pure and doped BMT at cryogenic temperatures is also discussed.
Publisher: American Chemical Society (ACS)
Date: 05-06-2828
Abstract: Graphene and its derivatives have acquired substantial research attention in recent years because of their wide range of potential applications. Implementing sustainable technologies for fabricating these functional nanomaterials is becoming increasingly apparent, and therefore, a wide spectrum of naturally derived precursors has been identified and reformed through various established techniques for the purpose. Nevertheless, most of these methods could only be considered partially sustainable because of their complexity as well as high energy, time, and resource requirements. Here, we report the fabrication of carbon nano-onion-interspersed vertically oriented multilayer graphene nanosheets through a single-step, environmentally benign radio frequency plasma-enhanced chemical vapor deposition process from a low-cost carbon feedstock, the oil from the peel of
Publisher: Wiley
Date: 03-03-2023
Abstract: Atmospheric pressure microwave plasma has the lead in synthesizing freestanding and scalable graphene within seconds without the need for high vacuum and temperature. However, the process is limited in utilizing chemical sources for synthesis, such as methane and ethanol. Herein, the usage of an extract of a sustainable precursor, that is, Melaleuca alternifolia , commonly known as tea tree, is for the first time reported to synthesize graphene nanosheets in atmospheric pressure microwave plasma. The synthesis is carried out in a single step at a remarkably low microwave power of 200 W. The morphology, structure, and electrochemical properties of graphene are studied using state‐of‐the‐art characterization techniques such as Raman spectroscopy, X‐ray diffraction, transmission electron microscopy (TEM) and electrochemical impedance spectroscopy. The TEM images reveal the presence of a combination of nanostructures such as nano‐horns, nano‐rods, or nano‐onions consisting of multi‐layer graphitic architectures. An excellent sensing capability of as‐synthesized graphene is demonstrated through the detection of diuron herbicide. A commendable linear range of 20 µ m to 1 m m and a limit of detection of 5 µ m of diuron is recorded.
Publisher: Elsevier BV
Date: 08-2002
Publisher: Springer Science and Business Media LLC
Date: 07-12-2006
DOI: 10.1007/S00204-006-0149-2
Abstract: Ingestion of non-steroidal anti-inflammatory drugs (NSAIDs) causes an enteropathy. The pathogenesis involves biochemical initiation of intestinal mucosal damage due to NSAID-induced inhibition of cyclooxygenase and the topical effects of these drugs. These effects lead to increased intestinal permeability and inflammation. Luminal bile acids play a controversial role in the damage produced by these drugs. The aim of this study was to determine the role of bile in producing the enteropathy caused by indomethacin, an NSAID commonly used in toxicity studies. Sprague-Dawley rats were subjected to bile duct ligation. Twenty-four hours later, they were dosed with indomethacin. Intestinal permeability ((51)Cr-EDTA) and inflammation (faecal calprotectin) were measured in the animals at various time periods after the dose. Intestinal permeability was significantly higher in rats 1-6 h after dosing with indomethacin, but not at 24-29 h or day 4, when compared with corresponding values for control animals. Excretion of faecal calprotectin was elevated in the indomethacin-treated rats. The drug-treated animals showed no evidence of ulceration when they were sacrificed 29 h or a week after the dose of indomethacin. Bile acids per se did not affect intestinal permeability or faecal excretion of calprotectin, when given along with indomethacin or its vehicle. We conclude that macroscopic small bowel damage does not occur with indomethacin if bile is excluded, despite the induction of permeability and inflammation. This study highlights the importance of luminal factors, such as bile, in producing indomethacin-induced ulceration in the rat small intestine.
Publisher: Elsevier BV
Date: 04-2008
Publisher: Elsevier BV
Date: 11-2015
Publisher: MDPI AG
Date: 23-04-2014
Publisher: MDPI AG
Date: 05-04-2018
DOI: 10.20944/PREPRINTS201804.0060.V1
Abstract: The persistent issue of bacterial and fungal colonization of artificial implantable materials and decreasing efficacy of conventional systemic antibiotics used to treat implant-associated infections has led to the development of a wide range of antifouling and antibacterial strategies. This article reviews one such strategy where inherently biologically active renewable resources, i.e. secondary plant metabolites (SPMs) and their naturally occurring combinations (i.e. essential oils) are used for surface functionalization and synthesis of polymer thin films. With a distinct mode of antibacterial activity, broad spectrum of action and ersity of available chemistries, secondary plant metabolites present an attractive alternative to conventional antibiotics. However, their conversion from liquid to solid phase without significant loss of activity is not trivial. Using select ex les, this article shows how plasma techniques provide a sufficiently flexible and chemically reactive environment to enable the synthesis of biologically-active polymer-coatings from volatile renewable resources.
Publisher: Elsevier BV
Date: 02-2011
Publisher: Springer Science and Business Media LLC
Date: 23-03-2013
Publisher: Elsevier BV
Date: 02-2014
Publisher: MDPI AG
Date: 10-05-2018
Publisher: Elsevier BV
Date: 2003
Publisher: MDPI AG
Date: 23-09-2019
DOI: 10.3390/MA12193099
Abstract: In this report, the electrical properties of plasma polymer films functionalized with ZnO nanoparticles were investigated with respect to their potential applications in biomaterials and microelectronics fields. The nanocomposite films were produced using a single-step method that combines simultaneous plasma polymerization of renewable geranium essential oil with thermal decomposition of zinc acetylacetonate Zn(acac)2. The input power used for the deposition of composites were 10 W and 50 W, and the resulting composite structures were abbreviated as Zn/Ge 10 W and Zn/Ge 50 W, respectively. The electrical properties of pristine polymers and Zn olymer composite films were studied in metal–insulator–metal structures. At a quantity of ZnO of around ~1%, it was found that ZnO had a small influence on the capacitance and dielectric constants of thus-fabricated films. The dielectric constant of films with smaller-sized nanoparticles exhibited the highest value, whereas, with the increase in ZnO particle size, the dielectric constant decreases. The conductivity of the composites was calculated to be in the in the range of 10−14–10−15 Ω−1 m−1, significantly greater than that for the pristine polymer, the latter estimated to be in the range of 10−16–10−17 Ω−1 m−1.
Publisher: Elsevier BV
Date: 02-2012
Publisher: IEEE
Date: 12-2028
Publisher: World Scientific Pub Co Pte Lt
Date: 10-07-2009
DOI: 10.1142/S0217979209063122
Abstract: The microwave properties of some of the low cost materials which can be used in high frequency applications with low transmission losses are investigated in this paper. One of the most accurate microwave characterization techniques, Split Post Dielectric Resonator technique (SPDR) is used for the experimental investigation. The dielectric constants of the 3 materials scrutinized at room temperature and at 10K are 3.65, 2.42, 3.61 and 3.58, 2.48, 3.59 respectively. The corresponding loss tangent values are 0.00370, 0.0015, 0.0042 and 0.0025, 0.0009, 0.0025. The high frequency transmission losses are comparable with many of the conventional materials used in low temperature electronics and hence these materials could be implemented in such applications.
Publisher: Trans Tech Publications, Ltd.
Date: 08-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.123-125.323
Abstract: Poly(linalool) thin films were fabricated using RF plasma polymerisation. All films were found to be smooth, defect-free surfaces with average roughness of 0.44 nm. The FTIR analysis of the polymer showed a notable reduction in –OH moiety and complete dissociation of C=C unsaturation compared to the monomer, and presence of a ketone band absent from the spectrum of the monomer. Poly(linalool) were characterised by chain branching and a large quantity of short polymer chains. Films were optically transparent, with refractive index and extinction coefficient of 1.55 and 0.001 (at 500 nm) respectively, indicating a potential application as an encapsulating (protective) coating for circuit boards. The optical band gap was calculated to be 2.82 eV, which is in the semiconducting energy gap region.
Publisher: American Chemical Society (ACS)
Date: 19-01-2022
Abstract: Single-step, single-precursor synthesis of nitrogen-doped graphene oxide (N-GO) was demonstrated in this work. By choosing aniline as the sole source of carbon and nitrogen, N-GO films were fabricated using microwave plasma at a power as low as 80 W in atmospheric conditions. The aniline vapor dissociated under plasma formed islands of N-GO nanosheets on the substrates or walls of the quartz deposition chamber. The interplanar spacing in the pristine N-GO films was observed to be lower than that of GO films, which indicated a lower concentration of oxygen and other species present in the space between the N-GO layers. The as-fabricated N-GO demonstrated superior antiscaling and algicidal properties that are deemed imperative for water purification applications.
Publisher: MDPI AG
Date: 28-01-2011
DOI: 10.3390/POLYM3010388
Publisher: Wiley
Date: 05-2007
Publisher: MDPI AG
Date: 21-12-2012
Publisher: IEEE
Date: 12-2006
Publisher: Springer Science and Business Media LLC
Date: 06-2008
Abstract: MgTe 2 O 5 ceramics were prepared by solid-state route. These materials were sintered in the temperature range of 640–720 °C. The structure and microstructure of the compound was investigated using x-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM) techniques. The dielectric properties of the ceramics were studied in the frequency range 4–6 GHz. The MgTe 2 O 5 ceramics have a dielectric constant (ϵ r ) of 10.5, quality factors ( Q u × f ) of 61000 at 5.3 GHz, and temperature coefficient of resonant frequency (τ f ) of −45 ppm/°C at the optimized sintering temperature of 700 °C. The microwave dielectric properties of these materials at cryogenic temperatures were also investigated.
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 06-2023
Publisher: Wiley
Date: 25-10-2002
DOI: 10.1002/MOP.10607
Publisher: Wiley
Date: 09-2009
Abstract: Polymer thin films derived from the essential oil of Lavandula angustifolia (LA) are fabricated using plasma polymerization, and their surface and chemical characteristics investigated. The surface morphology of the polyLA films is examined using an atomic force microscope (AFM). The polymer is found to be uniform and pinhole free, and the average roughness of the films is found to be less than a nanometer and independent of the RF power employed during fabrication. Fourier transform infrared (FTIR) spectroscopy analysis of the polyLA film is performed. Comparison of the FTIR spectra for polyLA film with that of the starting monomer demonstrates that many of the original functional groups are retained during the polymerization process. Bands assigned to CC stretching are lost due to their participation in the polymerization reactions. With increased RF power employed during fabrication, a decrease in intensity of most of the remaining bands in the FTIR spectra for the polyLA films is found. This is attributed to reactions such as dehydration of hydroxyl, cyclization, and aromatization associated with alkenes. In addition, it is found that the duration of exposure to UV irradiation and ion bombardment has an insignificant effect on the chemical structure of the polyLA film. Nuclear magnetic resonance (NMR) spectra of the polymer fabricated at low RF power reveals the presence of aromatics in the chemical structure. Water contact angle measurements demonstrate that the polyLA films range from mildly hydrophilic to mildly hydrophobic, and are stable while in contact with water.
Publisher: American Vacuum Society
Date: 11-2000
DOI: 10.1116/1.1314394
Abstract: Ultraviolet (UV)-transparent silicon nitride films were deposited in a plasma enhanced chemical vapor deposition reactor. The dependence of the film properties on process parameters has been studied. UV transmittance, refractive index, hydrogen content, and step coverage were compared to UV-opaque films. A significant difference in film growth between UV-opaque and UV-transparent SiNx layers has been detected. When film properties shift to an increased UV transparency, step coverage worsens significantly. This phenomenon is suggested to be caused by a strong reduction to Si–Si bonds for films below stoichiometric composition at low SiH4/NH3 gas flow ratios.
Publisher: IOP Publishing
Date: 17-11-2004
Publisher: MDPI AG
Date: 06-08-2021
DOI: 10.3390/MOLECULES26164762
Abstract: If plasma polymer thin films are to be synthesised from sustainable and natural precursors of chemically heterogeneous composition, it is important to understand the extent to which this composition influences the mechanism of polymerisation. To this end, a well-studied monoterpene alcohol, terpinen-4-ol, has been targeted for a comparative study with the naturally occurring mix of terpenes (viz. Melaleuca alternifolia oil) from which it is commonly distilled. Positive ion mode mass spectra of both terpinen-4-ol and M. alternifolia oil showed a decrease in disparities between the type and abundance of cationic species formed in their respective plasma environments as applied plasma power was increased. Supplementary biological assay revealed the antibacterial action of both terpinen-4-ol and M. alternifolia derived coatings with respect to S. aureus bacteria, whilst cytocompatibility was demonstrated by comparable eukaryotic cell adhesion to both coatings. Elucidating the processes occurring within the reactive plasmas can enhance the economics of plasma polymer deposition by permitting use of the minimum power, time and precursor pre-processing required to control the extent of monomer fragmentation and fabricate a film of the desired thickness and functionality.
Publisher: IOP Publishing
Date: 13-03-2009
Publisher: American Scientific Publishers
Date: 12-2012
Publisher: Trans Tech Publications, Ltd.
Date: 06-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.654-656.1764
Abstract: This study presents the effect of iodine doping on optical and surface properties of polyterpenol thin films deposited from non-synthetic precursor by means of plasma polymerisation. Spectroscopic ellipsometry studies showed iodine doping reduced the optical band gap from 2.82 eV to 1.50 eV for pristine and doped s les respectively. Higher levels of doping notably reduced the transparency of films, an issue if material is considered for applications that require high transparency. Contact angle studies demonstrated higher hydrophilicity for films deposited at increased doping levels, results confirmed by XPS Spectroscopy and FTIR. Doping had no significant effect on the surface profile or roughness of the film.
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.JENVMAN.2017.02.080
Abstract: The amount of biosolids increases every year, and social and environmental concerns are also rising due to heavy metals and pathogen contamination. Even though biosolids are considered as a waste material, they could be used as a precursor in several applications, especially in agriculture due to the presence of essential nutrients. Microwave assisted pyrolysis (MWAP) is a promising technology to safely manage biosolids, while producing value-added products, such as biochar, that can be used to improve soil fertility. This study examined the impact of pyrolysis temperature between 300 °C and 800 °C on the chemical and physical properties of biochar obtained from biosolids via MWAP. Preliminary phosphorus adsorption tests were carried out with the biochar produced from biosolids. This research demonstrated that pyrolysis temperature affects biochar specific surface area, ash and volatiles content, but does not impact heavily on the pH, chemical composition and crystalline phases of the resultant biochar. Biochar yield decreases as the pyrolysis temperature increases. Phosphorus adsorption capacity of biochar was approximately around 15 mg/g of biochar. Biochar resulting from MWAP is a potential candidate for land application with an important role in water and nutrient retention, due to the high surface area.
Publisher: Springer Science and Business Media LLC
Date: 18-05-2012
DOI: 10.1007/S00253-012-4144-7
Abstract: Biomaterials play a fundamental role in disease management and the improvement of health care. In recent years, there has been a significant growth in the ersity, function, and number of biomaterials used worldwide. Yet, attachment of pathogenic microorganisms onto biomaterial surfaces remains a significant challenge that substantially undermines their clinical applicability, limiting the advancement of these systems. The emergence and escalating pervasiveness of antibiotic-resistant bacterial strains makes the management of biomaterial-associated nosocomial infections increasingly difficult. The conventional post-operative treatment of implant-caused infections using systemic antibiotics is often marginally effective, further accelerating the extent of antimicrobial resistance. Methods by which the initial stages of bacterial attachment and biofilm formation can be restricted or prevented are therefore sought. The surface modification of biomaterials has the potential to alleviate pathogenic biofouling, therefore preventing the need for conventional antibiotics to be applied.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Springer Science and Business Media LLC
Date: 03-2007
Publisher: Elsevier BV
Date: 03-2010
Publisher: Informa UK Limited
Date: 30-09-2009
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.JENVMAN.2017.07.071
Abstract: The contamination of water with silver has increased due to the widespread applications of products with silver employed as antimicrobial agent. Adsorption is a cost-effective method for silver removal from aqueous solution. In this study biochar, produced from the microwave assisted pyrolysis of biosolids, was used for silver removal from an aqueous solution. The adsorption kinetics, isotherms and thermodynamics were investigated to better understand the silver removal process by biochar. X-ray diffraction results demonstrated that silver removal was a combination two consecutive mechanisms, reduction and physical adsorption. The Langmuir model fitted the experimental data well, showing that silver removal was predominantly a surface mechanism. The thermodynamic investigation demonstrated that silver removal by biochar was an exothermic process. The final nanocomposite Ag-biochar (biochar plus silver) was used for methylene blue adsorption and photodegradation. This study showed the potential of using biochar produced from biosolids for silver removal as a promising solution to mitigate water pollution and an environmentally sustainable approach for biosolids management and re-use.
Publisher: MDPI AG
Date: 27-01-2020
DOI: 10.3390/MA13030586
Abstract: Surface modification of thin films is often performed to enhance their properties. In this work, in situ modification of Terpinen-4-ol (T4) plasma polymer is carried out via simultaneous surface functionalization and nanoparticle immobilization. Terpinen-4-ol plasma polymers surface were decorated with a layer of ZnO nanoparticles in an oxygen plasma environment immediately after polymer deposition. A combination of hydrophilic modification and ZnO nanoparticle functionalization of the T4 polymer surface led to an enhancement in antibacterial properties by factor of 3 (from 0.75 to 0.25 CFU.mm−2). In addition, ZnO nanoparticle-modified coatings demonstrated improved UV absorbing characteristics in the region of 300–400 nm by 60% relative to unmodified coatings. The ZnO modified coatings were transparent in the visible region of 400–700 nm. The finding points towards the potential use of ZnO nanoparticle-modified T4 plasma polymers as optically transparent UV absorbing coatings.
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 2011
Publisher: IEEE
Date: 12-2008
Publisher: American Chemical Society (ACS)
Date: 24-10-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4RA17244B
Abstract: This article reviews antibacterial surface strategies based on reactive plasma chemistry, focusing on how plasma-assisted processing of natural antimicrobial agents can produce antifouling and antibacterial materials for biomedical devices.
Publisher: Wiley
Date: 03-04-2015
Publisher: MDPI AG
Date: 11-09-2017
DOI: 10.3390/MA10091066
Publisher: Wiley
Date: 06-11-2001
DOI: 10.1046/J.1365-2036.2001.01095.X
Abstract: A part of the mechanism of the gastrointestinal toxicity exhibited by non-steroidal anti-inflammatory drugs is believed to involve the uncoupling of mitochondrial oxidative phosphorylation. Most previous uncoupling studies have used rat liver mitochondria. There is little information on the effects of the drugs on mitochondria from other species. To study the effect of indometacin on isolated liver mitochondria from rats, mice and humans. We studied the effects of indometacin on respiration and adenosine triphosphate synthesis by isolated liver mitochondria from rats, mice and humans. Its effects were compared with those of dinitrophenol, a classical uncoupler. Indometacin uncoupled oxidative phosphorylation at low concentrations (P < 0.05) and inhibited respiration at high concentrations (P < 0.01) in all three species. Adenosine triphosphate synthesis was, however, more sensitive to dinitrophenol or indometacin at lower concentrations in mouse and human compared to rat liver mitochondria (P < 0.05). The current study shows that indometacin acts as an inhibitory uncoupler in human mitochondria. It also demonstrates that the responses of rat, mouse and human mitochondria to indometacin are broadly similar.
Publisher: IOP Publishing
Date: 11-1998
Publisher: Informa UK Limited
Date: 2005
Publisher: MDPI AG
Date: 13-09-2017
DOI: 10.3390/NANO7090270
Publisher: IEEE
Date: 2005
Publisher: Elsevier BV
Date: 06-2009
Publisher: Wiley
Date: 29-03-2022
Abstract: Bacterial infection of chronic wounds is a major healthcare problem that affects the quality of life of millions of patients worldwide and leads to a substantial healthcare cost burden. This project focused on the manufacture of a potential wound healing agent. Plasma polymers from oregano secondary metabolites (PP‐OSMs) were fabricated by radiofrequency plasma‐enhanced chemical vapor deposition (RF‐PECVD) in continuous and pulse plasma modes at room temperature. The surface, biocompatibility, and antibacterial properties of the PP‐OSMs were investigated. Polymers fabricated by RF‐PECVD retained the functional groups of OSMs, promoted human dermal fibroblast adhesion, inhibited Staphylococcus aureus attachment, and eliminated Pseudomonas aeruginosa . The PP‐OSM coatings are potential candidates for use in medical applications where cell biocompatibility and antibacterial properties are required.
Publisher: Elsevier BV
Date: 2011
Publisher: Springer Science and Business Media LLC
Date: 16-05-2012
Publisher: Elsevier BV
Date: 11-2013
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2005
Publisher: Springer Science and Business Media LLC
Date: 11-10-2006
No related grants have been discovered for Mohan Jacob.