No description available.

No description available.

In the period immediately following the implantation of a cochlear implant electrode array within the cochlear environment, the power required to stimulate the auditory nerve at preset current levels increases. This rise is due to increases in electrode impedance which in turn is suggested to be a result of tissue growth around the electrode array. The foreign body response initiated by the immune system encapsulates the array in a matrix of fibrous tissue, separating the electrode array from the rest of the body. A second change in electrode impedance occurs with the onset of electrical stimulation. A transitory reduction in impedance has been recorded in animals and humans after stimulation of electrodes. Impedance returns to pre-stimulation levels following the cessation of stimulation. It was suggested that these changes in impedance with stimulation were also related to the tissue growth around the electrode array. A more thorough understanding of the interface was required to ascertain these concepts.

<p>In this study, the main objective was to investigate the tolerance of platinum based binary anode catalysts for CO poisoning from 10ppm up to1000ppm and to identify the<br /> best anode catalysts for PEMFCs that tolerates the CO fed with reformed hydrogen.</p>

In this study, conductive particles will spray- coated onto the surface of the MPL to function as micro pillar structures that has been proved to be able to significantly increase the performance of a PEMFC. Contrast with the previously used nano imprint technology , the new method is cheap,fast, and especially suitable for the fabrication of large-area electrodes. The results show that a 30% increase in performance can be acquired by using 20um graphite particles. An increase of 57%, max power of 737mW/cm2 , may be achieved with irregular graphite flakes. The understanding of the distribution and the development of the produced water inside the cathode are essential to associate the performance increase with the microstructures. The electrode is dried gradually until a sharp increase in its impedance appeared, which indicates that the surface of the PEM begins to lose water. Then, i-v performance is measured through a cyclic test, i.e. , form a small load current to a large one and, then, buck to the small again. The performance improved with each cycle, because more and more water is produced along the test. A large performance ¡§jump¡¨ appearded at the 4th cycle only for the electrodes with the microstructure that indicates that the major reaction sites have shifted to the location of microstructures. It is concluded that, along with other evidence, a general water ¡§surface¡¨ exists and migrates form PEM towards MPL.

In this research, a static electric contact tester with a vacuum system is used to inverstigate the efedts of experimental parameters, such as air pressure, input voltage and current, contact material, and the gap between the contacts, on the electric-arc characteristics and the erosion debris type for the electric contacts of silver (Ag). The experiments are conducted under various experiment parameters, and the erosion debris is collected. After each experiment, the erosion debris will be calculated and observed to investigate the difference between erosion particles under various experiment conditions. Moreover, according to the results of the metallic phase and gaseous phase arc duration and the erosion particle type under various air pressures and the gaps, the electric-arc criterion and the erosion mechanism of DC electrical contacts will be established to provide the domestic electrical contact manufacture in improving the research and development technique of electrical contacts, and the design reference of super precision environment¡Xclean room

The use of XPS and AFS technique has been explored in the stLrly of the surface chemistry of a whole electrode surface (XPS) and the surface chemistry of natural pits (AFS). EDXA and to a snall extend SIMS were also used in the investigation of the individual pits. A high resolution Auger electron microscope which has an analytical resolution as snall as 0.1 .un enables a nevly formed pit of less than 2 .un in diameter to be investigated. By using a Cl/Mg ratio an attempt had been made to correlate the surface chemistry of whole electrodes exposed at different potentials in 1M MgCl2 solution to the surface chemistry of individual pits naturally produced qy means of a simulated metal to metal crevice made of cammercial stainless steels (SS316 and SS304) immersed in 1M MgCl2 solution. '!he correlation was fomd to be good and within the expected limit of the data produced by XPS and AFS. The estimated val ue of potentials of the surface of pit and its immediate vicinity was based on a theoretical model of variation of potential aromd a pit by Melville and also on the potential-current curve of the steel sample in the test sol ution. The Q/Mg ratio was shown to be useful in determining the activity of pits. In repassivated pits in the crevice mouth zone magnesiun was a dominant species relative to chlorine, this is in contrast to the pits in the central part of the crevice which were (ii) engulfed in general corrosion. Active pits in the area between the two regions have higher value of Cl./Mg ratio in their surface than that in the surface in their immediate vicinity. The role of chraniun in pitting corrosion is suggested to counter the pitting attack by the fonnation of chramiun oxide and oxy-chloride on the surface of pit. Molybdenun when present, also concentrates on the surface of pit. The type of corrosion attacks on sulphide inclusions in stainless steel depend on the copper content of the inclusions. Pitting will be likely to take place on pure MnS incl usions but not on copper enriched-MnS inclusions. The fonnation of copper sulphide is suggested to be important in reducing the amount of active species of sulphur on the corroded inclusions.

<p>In this study, the main objective was to investigate the tolerance of platinum based binary anode catalysts for CO poisoning from 10ppm up to1000ppm and to identify the<br /> best anode catalysts for PEMFCs that tolerates the CO fed with reformed hydrogen.</p>

No description available.

In the period immediately following the implantation of a cochlear implant electrode array within the cochlear environment, the power required to stimulate the auditory nerve at preset current levels increases. This rise is due to increases in electrode impedance which in turn is suggested to be a result of tissue growth around the electrode array. The foreign body response initiated by the immune system encapsulates the array in a matrix of fibrous tissue, separating the electrode array from the rest of the body. A second change in electrode impedance occurs with the onset of electrical stimulation. A transitory reduction in impedance has been recorded in animals and humans after stimulation of electrodes. Impedance returns to pre-stimulation levels following the cessation of stimulation. It was suggested that these changes in impedance with stimulation were also related to the tissue growth around the electrode array. A more thorough understanding of the interface was required to ascertain these concepts.