33 resultados para gold film electrode
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J Biol Inorg Chem (2007) 12:691–698 DOI 10.1007/s00775-007-0219-9
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Understanding how the brain works will require tools capable of measuring neuron elec-trical activity at a network scale. However, considerable progress is still necessary to reliably increase the number of neurons that are recorded and identified simultaneously with existing mi-croelectrode arrays. This project aims to evaluate how different materials can modify the effi-ciency of signal transfer from the neural tissue to the electrode. Therefore, various coating materials (gold, PEDOT, tungsten oxide and carbon nano-tubes) are characterized in terms of their underlying electrochemical processes and recording ef-ficacy. Iridium electrodes (177-706 μm2) are coated using galvanostatic deposition under different charge densities. By performing electrochemical impedance spectroscopy in phosphate buffered saline it is determined that the impedance modulus at 1 kHz depends on the coating material and decreased up to a maximum of two orders of magnitude for PEDOT (from 1 MΩ to 25 kΩ). The electrodes are furthermore characterized by cyclic voltammetry showing that charge storage capacity is im-proved by one order of magnitude reaching a maximum of 84.1 mC/cm2 for the PEDOT: gold nanoparticles composite (38 times the capacity of the pristine). Neural recording of spontaneous activity within the cortex was performed in anesthetized rodents to evaluate electrode coating performance.
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Eur. J. Biochem. 271, 1329–1338 (2004)
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Journal of Electroanalytical Chemistry 541 (2003) 153-162
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Advanced Materials, Vol. 17, nº 5
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Thin Solid Films, vol. 427, nº 1-2
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Applied Physics Letters, 89
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Quimica Nova, Vol. 32, Nº2
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The Mondunguara copper mines are situated in mountainous terrain in west-central Mozambique. The mineralization consists of chalcopyrite, pyrrhotite, common pcntlandite, cobaltpentlandite, pyrite and several minor oxides and sulphides in tabular ore bodies deeping steep to the north. Gold was known to occur in small quantities but no systematic sampling and analysis for precious clements was ever done. Mineralogical and geological evidence has shown that the ores are magmatic in origin and were derived from gabbro-peridotitic magma dykes saturated in sulphides when intruded. The ore bodies show a clear zonation. Platinum group elements as well as pure gold are associated with high temperature hexagonal pyrrhotite. This pyrrhotite being of no use is generally discarded to the tailing dumps. Late hydrothermal phases are enriched in native silver, silver tellurides as well as electrum.
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In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Nanotechnologies and Nanosciences by Universidade Nova de Lisboa Faculdade de Ciências e Tecnologia
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Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina
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Dissertação para obtenção do Grau de Mestre em Biotecnologia
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Thesis for the Master degree in Structural and Functional Biochemistry
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Dissertação para obtenção do Grau de Mestre em Biotecnologia
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Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica