The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
C Mary - One of the best experts on this subject based on the ideXlab platform.
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pressure and temperature effects on fretting wear damage of a cu ni in Plasma Coating versus ti17 titanium alloy contact
Wear, 2011Co-Authors: C Mary, S Fouvry, J M Martin, B BonnetAbstract:Abstract Fretting wear is a surface degradation process induced by small-amplitude oscillatory movements between contacting bodies. It may result in critical wear, especially in the blade/disk contact of aero-engines. To focus on this industrial issue, an experimental layout was designed to perform fretting wear tests up to 500 °C. A representative punch (Ti17)/plane (CuNiIn Plasma Coating) interface was investigated under air conditions. Wear regimes were identified regarding variations of parameters such as pressure, sliding amplitude and temperature. Chemical analyses (EDS, XRD, XPS) performed on fretting scars enabled the characterization of degradation mechanisms. A quantitative description based on an energy wear approach is introduced to predict the wear kinetics as a function of contact loading parameters. It is shown that temperature plays a minor role. By contrast, the mean pressure appears as a key factor, modifying the interface structure and consequently the wear kinetics: the higher the mean pressure, the higher the wear rate. Surface investigations show that above a threshold mean pressure ( p _th), Ti transfer from the punch toward the CuNiIn Plasma Coating is activated. The punch interface is then characterized by a composite structure displaying a central nitrided TTS layer, surrounded by an oxidized rim. The activation of the nitrided TTS structure is shown to be function of the mean contact pressure and the contact geometry. Indeed, the “nitriding process” which is induced by an over plastic strain accumulation, depends on the local concentration of oxygen within the interface. When most of the oxygen of the air is consumed in the lateral rim of the interface (oxided third body), the “contact nitriding process” takes place. Hence the global wear kinetics is greatly modified depending on whether the pressure is below or above the pressure threshold. However it is shown that considering a local energy wear approach and taking into account the Ti transfer layer on the CuNiIn surface, the global wear rate obtained under high pressure conditions (i.e. p > p _th) can be predicted using the energy wear rates identified under low pressure conditions ( p p _th).
B Bonnet - One of the best experts on this subject based on the ideXlab platform.
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pressure and temperature effects on fretting wear damage of a cu ni in Plasma Coating versus ti17 titanium alloy contact
Wear, 2011Co-Authors: C Mary, S Fouvry, J M Martin, B BonnetAbstract:Abstract Fretting wear is a surface degradation process induced by small-amplitude oscillatory movements between contacting bodies. It may result in critical wear, especially in the blade/disk contact of aero-engines. To focus on this industrial issue, an experimental layout was designed to perform fretting wear tests up to 500 °C. A representative punch (Ti17)/plane (CuNiIn Plasma Coating) interface was investigated under air conditions. Wear regimes were identified regarding variations of parameters such as pressure, sliding amplitude and temperature. Chemical analyses (EDS, XRD, XPS) performed on fretting scars enabled the characterization of degradation mechanisms. A quantitative description based on an energy wear approach is introduced to predict the wear kinetics as a function of contact loading parameters. It is shown that temperature plays a minor role. By contrast, the mean pressure appears as a key factor, modifying the interface structure and consequently the wear kinetics: the higher the mean pressure, the higher the wear rate. Surface investigations show that above a threshold mean pressure ( p _th), Ti transfer from the punch toward the CuNiIn Plasma Coating is activated. The punch interface is then characterized by a composite structure displaying a central nitrided TTS layer, surrounded by an oxidized rim. The activation of the nitrided TTS structure is shown to be function of the mean contact pressure and the contact geometry. Indeed, the “nitriding process” which is induced by an over plastic strain accumulation, depends on the local concentration of oxygen within the interface. When most of the oxygen of the air is consumed in the lateral rim of the interface (oxided third body), the “contact nitriding process” takes place. Hence the global wear kinetics is greatly modified depending on whether the pressure is below or above the pressure threshold. However it is shown that considering a local energy wear approach and taking into account the Ti transfer layer on the CuNiIn surface, the global wear rate obtained under high pressure conditions (i.e. p > p _th) can be predicted using the energy wear rates identified under low pressure conditions ( p p _th).
Hongmin Sun - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of Staphylococcus epidermidis biofilm by trimethylsilane Plasma Coating
Antimicrobial Agents and Chemotherapy, 2012Co-Authors: Yibao Ma, John E Jones, Andy Charles Ritts, Qingsong Yu, Meng Chen, Hongmin SunAbstract:Biofilm formation on implantable medical devices is a major impediment to the treatment of nosocomial infections and promotes local progressive tissue destruction. Staphylococcus epidermidis infections are the leading cause of biofilm formation on indwelling devices. Bacteria in biofilms are highly resistant to antibiotic treatment, which in combination with the increasing prevalence of antibiotic resistance among human pathogens further complicates treatment of biofilm-related device infections. We have developed a novel Plasma Coating technology. Trimethylsilane (TMS) was used as a monomer to coat the surfaces of 316L stainless steel and grade 5 titanium alloy, which are widely used in implantable medical devices. The results of biofilm assays demonstrated that this TMS Coating markedly decreased S. epidermidis biofilm formation by inhibiting the attachment of bacterial cells to the TMS-coated surfaces during the early phase of biofilm development. We also discovered that bacterial cells on the TMS-coated surfaces were more susceptible to antibiotic treatment than their counterparts in biofilms on uncoated surfaces. These findings suggested that TMS Coating could result in a surface that is resistant to biofilm development and also in a bacterial community that is more sensitive to antibiotic therapy than typical biofilms.
E Suzuki - One of the best experts on this subject based on the ideXlab platform.
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high resolution scanning electron microscopy of immunogold labelled cells by the use of thin Plasma Coating of osmium
Journal of Microscopy, 2002Co-Authors: E SuzukiAbstract:Summary The feasibility of Plasma Coating of a thin osmium layer for high-resolution immuno-scanning electron microscopy of cell surfaces was tested, using Drosophila embryonic motor neurones as a model system. The neuro-muscular preparations were fixed with formaldehyde and labelled with a neurone-specific antibody and 10 or 5 nm colloidal gold-conjugated secondary antibodies. The specimens were post-fixed with osmium tetroxide and freeze-dried. Then they were coated with a 1–2 nm thick layer of osmium using a hollow cathode Plasma coater. The thin and continuous Coating of amorphous osmium gave good signals of gold particles and fine surface structures of neurites in backscattered electron images simultaneously. This method makes it possible to visualize the antigen distribution and the three-dimensionally complex surface structures of cellular processes with a resolution of several nanometres.
Yibao Ma - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of Staphylococcus epidermidis biofilm by trimethylsilane Plasma Coating
Antimicrobial Agents and Chemotherapy, 2012Co-Authors: Yibao Ma, John E Jones, Andy Charles Ritts, Qingsong Yu, Meng Chen, Hongmin SunAbstract:Biofilm formation on implantable medical devices is a major impediment to the treatment of nosocomial infections and promotes local progressive tissue destruction. Staphylococcus epidermidis infections are the leading cause of biofilm formation on indwelling devices. Bacteria in biofilms are highly resistant to antibiotic treatment, which in combination with the increasing prevalence of antibiotic resistance among human pathogens further complicates treatment of biofilm-related device infections. We have developed a novel Plasma Coating technology. Trimethylsilane (TMS) was used as a monomer to coat the surfaces of 316L stainless steel and grade 5 titanium alloy, which are widely used in implantable medical devices. The results of biofilm assays demonstrated that this TMS Coating markedly decreased S. epidermidis biofilm formation by inhibiting the attachment of bacterial cells to the TMS-coated surfaces during the early phase of biofilm development. We also discovered that bacterial cells on the TMS-coated surfaces were more susceptible to antibiotic treatment than their counterparts in biofilms on uncoated surfaces. These findings suggested that TMS Coating could result in a surface that is resistant to biofilm development and also in a bacterial community that is more sensitive to antibiotic therapy than typical biofilms.