Electron Energy Loss Spectroscopy
Mostrando 13-24 de 29 artigos, teses e dissertações.
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13. Obtaining magnesium and vanadium catalysts supported on activated carbon for the production of styrene. / Obtenção de catalisadores de vanádio e magnésio suportados em carvão ativado para a produção de estireno.
The main route industrially used for styrene production is the ethylbenzene catalytic dehydrogenation, responsible for more than 90% of its worldwide capacity. The industrial process is performed at the temperature range of 550-700 C with an excess of heated steam over potassium and chromium-promoted iron oxide catalysts, which are toxic and have 2-year life
Publicado em: 2008
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14. Modificação das propriedades superficiais de materiais através da implantação de cromo por recoil por meio de implantação iônica por imersão em plasma de nitrogênio / Modification of surface properties of materials by chromium recoil implantation using nitrogen plasma immersion ion implantation
The objective of this work is the modification of the surface properties of conductive materials (carbon steel) and semiconductors (silicon) using the implantation of chromium atoms, deposited on the surface of materials as thin films, using plasma immersion ion implantation. In this study we seek to understand the basic process of recoil implantation (using
Publicado em: 2007
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15. Rubber-brass adhesion to tire steel cords- the influence of cobalt, the HMMM (Hexamethoxymethylmelamine)-resorcinol system and the temperature at the interface. / Adesão borracha-latão: a influência do cobalto, do sistema HMMM (hexametoximetilmelamina)-resorcinol e da temperatura na interface.
Using a blank compound as reference and brass coated steel tire cords with 64 and 68.2 % of cooper content, it was studied the effect of the ingredients cobalt and the HMMM-resorcinol system, and the vulcanization temperature on the rubber-brass adhesion. Samples were studied as new (original), aged in oven, steam and humidity environments. Mechanical proper
Publicado em: 2006
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16. Implantação ionica em filmes finos depositados por PECVD
This work reports the influence of the ion implantation on the properties of thin plasma polymer films deposited from radiofrequency (40 MHz, 70 W) plasmas of two organic compounds (acetylene and benzene) and from their mixtures with noble gases. The irradiations were performed with an ion implanter, using He+, N+ and Ar+ ions, in the fluence and energy rang
Publicado em: 1999
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17. Adsorção e ordenamento moleculares sobre paladio (111) : um estudo por HREELS e LEED
Monocamadas de oxigênio coadsorvido com acetileno e etileno em uma superfície de Pd(111) foram estudadas por Espectroscopia de Alta Resolução por Perdas Energéticas de Elétrons ( "High Resolution Electron Energy Loss Spectroscopy" -HREELS) e Difração de Elétrons de Baixa Energia ("Low Energy Electron Diffraction" -LEED) a temperaturas de 150 a 320 K
Publicado em: 1991
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18. Phosphorylation and subunit organization of axonal neurofilaments determined by scanning transmission electron microscopy
Phosphorylation plays a critical role in controlling the function of cytoskeletal assemblies but no direct method yet exists to measure the phosphorylation state of proteins at the level of individual molecules and assemblies. Herein, we apply scanning transmission electron microscopy in combination with electron energy loss spectroscopy to measure the distr
National Academy of Sciences.
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19. High resolution ultrastructural mapping of total calcium: electron spectroscopic imaging/electron energy loss spectroscopy analysis of a physically/chemically processed nerve-muscle preparation.
We report on a procedure for tissue preparation that combines thoroughly controlled physical and chemical treatments: quick-freezing and freeze-drying followed by fixation with OsO4 vapors and embedding by direct resin infiltration. Specimens of frog cutaneous pectoris muscle thus prepared were analyzed for total calcium using electron spectroscopic imaging/
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20. Electron microscopic study of the effect of zinc on Tritrichomonas foetus.
At concentrations of 3.1 to 24 mM, zinc inhibits the multiplication of and kills the pathogenic protozoan Tritrichomonas foetus. Transmission electron microscopy showed that the hydrogenosome, a organelle which is involved in the metabolism of pyruvate and the site of formation of molecular hydrogen, constitutes the main site of the initial effect of zinc. T
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21. Growth of Polychlorinated-Biphenyl-Degrading Bacteria in the Presence of Biphenyl and Chlorobiphenyls Generates Oxidative Stress and Massive Accumulation of Inorganic Polyphosphate
Inorganic polyphosphate (polyP) plays a significant role in increasing bacterial cell resistance to unfavorable environmental conditions and in regulating different biochemical processes. Using transmission electron microscopy of the polychlorinated biphenyl (PCB)-degrading bacterium Pseudomonas sp. strain B4 grown in defined medium with biphenyl as the sole
American Society for Microbiology.
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22. A “midinfrared” scenario for cuprate superconductivity
I conjecture that the mechanism of superconductivity in the cuprates is a saving, due to the improved screening resulting from Cooper pair formation, of the part of the Coulomb energy associated with long wavelengths and midinfrared frequencies. This scenario is shown to provide a plausible explanation of the trend of transition temperature with layerin
The National Academy of Sciences.
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23. Electron probe analysis, X-ray mapping, and electron energy-loss spectroscopy of calcium, magnesium, and monovalent ions in log-phase and in dividing Escherichia coli B cells.
The elemental composition of individual cells of rapidly frozen and cryosectioned Escherichia coli B was measured with electron optical microanalytic methods. The Ca content was high (26.2 mmol/kg) in a 10-nm-wide region of the cell envelope. Amounts of cytoplasmic Ca in actively dividing cells were significantly higher (32.6 mmol/kg [dry weight]) than in th
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24. High-resolution calcium mapping of the endoplasmic reticulum-Golgi-exocytic membrane system. Electron energy loss imaging analysis of quick frozen-freeze dried PC12 cells.
The calcium pools segregated within the endoplasmic reticulum, Golgi complex, exocytic, and other organelles are believed to participate in the regulation of a variety of cell functions. Until now, however, the precise intracellular distribution of the element had not been established. Here, we report about the first high-resolution calcium mapping obtained