The Experts below are selected from a list of 279000 Experts worldwide ranked by ideXlab platform
Herhsiung Huang - One of the best experts on this subject based on the ideXlab platform.
-
Surface Characterization of passive film on nicr based dental casting alloys
2003Co-Authors: Herhsiung HuangAbstract:Abstract Surface Characterization of passive film formed on different NiCr-based dental casting alloys in an acidic artificial saliva was investigated by using electrochemical impedance spectroscopy (EIS) measurement and potential decay test. The polarization resistance ( R p ), which is inversely proportional to corrosion rate, of passive film was obtained from the EIS data. The stable passive current density, passivating rate, and passivity decay rate of passive film were evaluated by potential decay test. Surface chemical analyses of passive film were performed by using X-ray photoelectron spectrometer and Auger electron spectrometer. Results showed that the R p , stable passive current density, passivating rate, and passivity decay rate, respectively, were significantly different among the various NiCr-based alloys ( p 2 O 3 ) and Mo (maximum 10–11 at%; mainly as MoO 3 ) contents in the passive film led to a higher R p , lower stable passive current density, faster passivating rate, and lower passivity decay rate. The presence of Be (>20 at%; mainly as BeO) in the passive film was detrimental to both the corrosion resistance and the stability of passive film. The presence of small amount of Ti ( 2 ) in the passive film did not show any influence on the Characterization of passive film.
-
Surface Characterization of passive film on nicr based dental casting alloys
2003Co-Authors: Herhsiung HuangAbstract:Abstract Surface Characterization of passive film formed on different NiCr-based dental casting alloys in an acidic artificial saliva was investigated by using electrochemical impedance spectroscopy (EIS) measurement and potential decay test. The polarization resistance ( R p ), which is inversely proportional to corrosion rate, of passive film was obtained from the EIS data. The stable passive current density, passivating rate, and passivity decay rate of passive film were evaluated by potential decay test. Surface chemical analyses of passive film were performed by using X-ray photoelectron spectrometer and Auger electron spectrometer. Results showed that the R p , stable passive current density, passivating rate, and passivity decay rate, respectively, were significantly different among the various NiCr-based alloys ( p 2 O 3 ) and Mo (maximum 10–11 at%; mainly as MoO 3 ) contents in the passive film led to a higher R p , lower stable passive current density, faster passivating rate, and lower passivity decay rate. The presence of Be (>20 at%; mainly as BeO) in the passive film was detrimental to both the corrosion resistance and the stability of passive film. The presence of small amount of Ti ( 2 ) in the passive film did not show any influence on the Characterization of passive film.
David G Castner - One of the best experts on this subject based on the ideXlab platform.
-
Surface Characterization of extracellular matrix scaffolds
2010Co-Authors: Bryan N Brown, David G Castner, Buddy D Ratner, Chris Barnes, Rena T Kasick, Roger Michel, Thomas W Gilbert, Donna Beerstolz, Stephen F BadylakAbstract:Extracellular matrix (ECM) scaffolds prepared from different tissue sources or using different methods have been demonstrated to have distinctive effects upon cell adhesion patterns and the ability to support and maintain differentiated phenotypes. It is unknown whether the molecular composition or the ultrastructure of the ECM plays a greater role in determining the phenotype of the cells with which it comes into contact. However, when implanted, the topology and ligand landscape of the material will determine the host molecules that bind and the type and behavior of cells that mediate the host response. Therefore, a comprehensive understanding of Surface characteristics is essential in the design of scaffolds for specific clinical applications. The Surface characteristics of ECM scaffolds derived from porcine urinary bladder, small intestine, and liver as well as the effects of two commonly used methods of chemical cross-linking upon UBM were investigated. Electron microscopy and time of flight secondary ion mass spectroscopy were used to examine the Surface characteristics of the scaffolds. The results show that ECM scaffolds have unique morphologic and structural properties which are dependant on the organ or tissue from which the scaffold is harvested. Furthermore, the results show that the Surface characteristics of an ECM scaffold are changed through chemical cross-linking.
-
Surface Characterization of the extracellular matrix remaining after cell detachment from a thermoresponsive polymer
2005Co-Authors: Heather E Canavan, Daniel J Graham, Xuanhong Cheng, Buddy D Ratner, David G CastnerAbstract:The temperature-responsive behavior of poly(N-isopropyl acrylamide) (pNIPAM) directly affects the attachment and detachment of cells cultured on these Surfaces. At culture temperatures, cells behave similarly to those on tissue culture polystyrene (TCPS), while at room temperature, cells cultured on pNIPAM spontaneously detach as a confluent sheet. In comparison, cells grown on TCPS remain attached indefinitely after the temperature drop, requiring enzymatic or mechanical removal. In this work, we present an examination of the response of bovine aortic endothelial cells (BAECs) and extracellular matrix (ECM) proteins to plasma polymerized NIPAM (ppNIPAM) Surfaces using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and immunostaining. Immunoassay results reveal that, although fibronectin, laminin, and collagen closely associate with the cell sheet, some collagen may be associated with the Surface, as well. Our XPS results indicate that ppNIPAM Surfaces after cell liftoff differ from their blank counterparts, the primary distinction being the presence of amide and alcohol species on ppNIPAM Surfaces used for cell culture, possibly owing to the presence of a proteinaceous film. Finally, a comparison between ppNIPAM-treated Surfaces used for cell culture versus control Surfaces by principal component analysis of the ToF-SIMS data confirms that the Surfaces differ; the presence of molecular ion fragments from amino acids (e.g., alanine, glycine, and proline) is the chief reason for this difference. Therefore, from our Surface Characterization of ppNIPAM-coated TCPS after cell liftoff, we conclude that although low-temperature liftoff of the BAEC monolayer is accompanied by the majority of the components of the ECM, some of the ECM proteins still remain at the Surface.
-
time of flight secondary ion mass spectrometry techniques and applications for the Characterization of biomaterial Surfaces
2003Co-Authors: Anna M. Belu, Daniel J Graham, David G CastnerAbstract:The Surface of a biomaterial plays a critical role in the success of an implant. Much effort is currently being focused on controlling the chemistry at biomaterial Surfaces to ensure favorable results in vivo. The successful tailoring of the Surface chemistry will require a detailed Surface Characterization to verify that the desired changes have been made. This will include the ability to determine the composition, structure, orientation, and spatial distribution, of the molecules and chemical structures on the Surface. TOF-SIMS is a powerful Surface Characterization technique that is able to address these requirements through both spectral analysis and direct chemical state imaging. The flexibility of the TOF-SIMS technique, and the wealth of data produced have generated much interest in its use for biomaterial Characterization. This review discusses the strengths, weaknesses, and challenges of static TOF-SIMS for biomaterial Surface Characterization. First the basic principles of TOF-SIMS are introduced, giving an overview of the technique. Next, sample type, and other sample considerations are discussed. Then data interpretation is overviewed using examples from both spectral and imaging data. Finally, quantitative SIMS analysis is discussed and an outlook for TOF-SIMS analysis of biomaterials will be given.
Maria Manca C De Nadra - One of the best experts on this subject based on the ideXlab platform.
-
flocculation and cell Surface Characterization of kloeckera apiculata from wine
2003Co-Authors: M E Farias, Maria Manca C De NadraAbstract:AIMS: To characterize and analyze the flocculation phenomenon of Kloeckera apiculata mc1 from Argentinian wine to understand the cell-cell interaction pattern. METHODS AND RESULTS: Kloeckera apiculata mc1 possess intense cell-cell interactions in MYPG medium (0.5% malt extract, 1% yeast extract, 2% glucose, 2% peptone), pH 5.5 by shaking at 25 degrees C. Optimum flocculation is observed at pH 4.5 in the presence of 3 mmol l-1 Ca2+. The flocculation is induced by peptone and malt extract and not by yeast extract and is reversed by 50 mmol l-1 galactose or lactose. The flocculation is highly susceptible to pronase, chymotrypsine and proteases types IV and XXVII and is partially resistant to trypsin. The electronic microscopy shows that the cells are attached to each other along their sides by fine hair-like threads. CONCLUSIONS: The mechanism of flocculation of K. apiculata mc1 is mediated by protein-carbohydrate interaction, stabilized by Ca2+. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of selected pure yeast inocula of known ability is preferred to wine elaboration, therefore the indigenous flora must be avoided and the flocculation of K. apiculata could be an economic method to do it.
-
flocculation and cell Surface Characterization of kloeckera apiculata from wine
2003Co-Authors: Maria Manca C De Nadra, M E FariasAbstract:Aims: To characterize and analyze the flocculation phenomenon of Kloeckera apiculata mc1 from Agentinian wine to understand the cell–cell interaction pattern. Methods and Results:Kloeckera apiculata mc1 possess intense cell–cell interactions in MYPG medium (0·5% malt extract, 1% yeast extract, 2% glucose, 2% peptone), pH 5·5 by shaking at 25°C. Optimum flocculation is observed at pH 4·5 in the presence of 3 mmol l−1 Ca2+. The flocculation is induced by peptone and malt extract and not by yeast extract and is reversed by 50 mmol l−1 galactose or lactose. The flocculation is highly susceptible to pronase, chymotrypsine and proteases types IV and XXVII and is partially resistant to trypsin. The electronic microscopy shows that the cells are attached to each other along their sides by fine hair-like threads. Conclusions: The mechanism of flocculation of K. apiculata mc1 is mediated by protein–carbohydrate interaction, stabilized by Ca2+. Significance and Impact of the Study: The use of selected pure yeast inocula of known ability is preferred to wine elaboration, therefore the indigenous flora must be avoided and the flocculation of K. apiculata could be an economic method to do it.
Xianming Wang - One of the best experts on this subject based on the ideXlab platform.
-
electrode structure analysis and Surface Characterization for lithium ion cells simulated low earth orbit satellite operation ii electrode Surface Characterization
2007Co-Authors: Xianming Wang, Toshiya Hironaka, Eiji Hayashi, Chisa Yamada, Hitoshi Naito, Go Segami, Yoko Sakiyama, Yoshikazu Takahashi, Koichi KibeAbstract:Abstract As a sequence work to investigate the performance-degradation mechanism of an aged commercial laminated lithium-ion cell experiencing 4350-cycle charge–discharge in a simulated low-Earth-orbit (LEO) satellite operation, we performed the Surface Characterization of LiCoO 2 cathode and graphite anode by Fourier transform infrared-Attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analysis in this work. Overall, the graphite anode had a larger change in Surface chemistry than that of the LiCoO 2 cathode. Except the common Surface components, we detected Co metal at the aged graphite Surface in the first time. This Co metal deposition was believed to originate from Co 2+ dissolution from LiCoO 2 cathode during prolonged cycling, and detrimental to structure stability of LiCoO 2 cathode which was a main cause of cell capacity loss. The amount of Surface-film component was also estimated by FTIR analysis. Though the total amount of Surface film increased, the organic (inorganic) Surface film decreased (increased) with prolonged cycling.
-
electrode structure analysis and Surface Characterization for lithium ion cells simulated low earth orbit satellite operation i electrochemical behavior and structure analysis
2007Co-Authors: Xianming Wang, Toshiya Hironaka, Eiji Hayashi, Chisa Yamada, Hitoshi Naito, Go Segami, Yoko Sakiyama, Yoshikazu Takahashi, Kouichi KibeAbstract:Abstract Lithium-ion cells for satellite applications operate under a special condition, and are expected to behave differently from those for commercial purposes. To understand the performance-degradation mechanism of lithium-ion cells experienced cycle-life testing in a simulated low-Earth-orbit (LEO) satellite operation, we conducted the structure analysis and Surface Characterization of the aged LiCoO 2 cathode and graphite anode obtained from a lithium-ion cell with 4350-cycle LEO simulation experience. The analysis results were compared with a fresh cell which served as control. This paper provides a review of testing results on electrochemical and structure analysis. The capacity-verification and impedance measure results indicated that the LiCoO 2 cathode, rather than graphite anode, was responsible for the performance degradation of the aged cell. This conclusion was confirmed by the structure analysis. The qualitative analysis of the XRD spectra disclosed that the aged cathode exhibited a much larger structure change than the aged anode. We also detected the lithium ions that were irreversibly reserved in graphite anode in XRD and 7 Li nuclear magnetic resonance (NMR) analysis of aged graphite anode. These results lead us to deduce that the serious structure change in LiCoO 2 cathode was primarily responsible for the performance degradation of the aged cell.
Kouichi Kibe - One of the best experts on this subject based on the ideXlab platform.
-
electrode structure analysis and Surface Characterization for lithium ion cells simulated low earth orbit satellite operation i electrochemical behavior and structure analysis
2007Co-Authors: Xianming Wang, Toshiya Hironaka, Eiji Hayashi, Chisa Yamada, Hitoshi Naito, Go Segami, Yoko Sakiyama, Yoshikazu Takahashi, Kouichi KibeAbstract:Abstract Lithium-ion cells for satellite applications operate under a special condition, and are expected to behave differently from those for commercial purposes. To understand the performance-degradation mechanism of lithium-ion cells experienced cycle-life testing in a simulated low-Earth-orbit (LEO) satellite operation, we conducted the structure analysis and Surface Characterization of the aged LiCoO 2 cathode and graphite anode obtained from a lithium-ion cell with 4350-cycle LEO simulation experience. The analysis results were compared with a fresh cell which served as control. This paper provides a review of testing results on electrochemical and structure analysis. The capacity-verification and impedance measure results indicated that the LiCoO 2 cathode, rather than graphite anode, was responsible for the performance degradation of the aged cell. This conclusion was confirmed by the structure analysis. The qualitative analysis of the XRD spectra disclosed that the aged cathode exhibited a much larger structure change than the aged anode. We also detected the lithium ions that were irreversibly reserved in graphite anode in XRD and 7 Li nuclear magnetic resonance (NMR) analysis of aged graphite anode. These results lead us to deduce that the serious structure change in LiCoO 2 cathode was primarily responsible for the performance degradation of the aged cell.
