999 resultados para Óxido nítrico sintase Teses
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Ps-graduao em Educao para a Cincia - FC
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Coordenao de Aperfeioamento de Pessoal de Nvel Superior (CAPES)
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Coordenao de Aperfeioamento de Pessoal de Nvel Superior (CAPES)
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Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Cientfico e Tecnolgico (CNPq)
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Ps-graduao em Cincia e Tecnologia de Materiais - FC
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Ps-graduao em Biotecnologia - IQ
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Coordenao de Aperfeioamento de Pessoal de Nvel Superior (CAPES)
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Coordenao de Aperfeioamento de Pessoal de Nvel Superior (CAPES)
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Coordenao de Aperfeioamento de Pessoal de Nvel Superior (CAPES)
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Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)
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Fuel cells powered directly with ethanol (Direct Ethanol Fuel Cell-DEFC) are very attractive for the possibility of using a renewable fuel in the generation of clean energy. However, it is still necessary to deepen the understanding of catalytic processes and their dependence on the catalytic properties. This work proposes to study the catalytic activity of ethanol oxidation in an alkaline medium of Pd nanoparticles supported in carbon oxide hybrids using various transition metal oxides (MoO3, TiO2, WO3 and ZrO2). The materials prepared were characterized by techniques such as X-ray diffraction, transmission electron microscopy (TEM) and X-ray dispersive spectroscopy (EDX) to verify the structure, the distribution of particles in the supports and the presence of Pd on particles oxide. Experiments of X-rays absorption spectroscopy were carried out using soft X-rays (SXS) to evaluate the changes in the electronic properties of the Pd particles caused by interactions with different oxides. Measurements of cyclic voltammetry and potential sweeps of adsorbed CO oxidation allowed evaluating general aspects of the catalysts' electrochemical behavior and determining the electrochemically active area thereof. The catalytic performances of ethanol oxidation in alkaline medium were evaluated by electrochemical techniques (potential scan and chronoamperometry), and showed an improvement in activity with the addition of oxides in material containing only carbon, which was most pronounced for the catalyst containing TiO2. This improvement was predominantly associated with the electronic effects caused by the interaction of Pd on the support, causing a vacancy in the 4d band of Pd which, in turn, produces variations in adsorption energies of the species...
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Levando em conta o modelo de desenvolvimento vigente, consideramos o momento atual, de crise ambiental, como fruto do estabelecimento de uma postura antropocntrica frente natureza. Assim, a EA vem sendo apontada como uma das possibilidades de mudana deste cenrio. A EA que propomos se apoia em trs dimenses, estabelecidas por Carvalho (1989), com especial enfoque na dimenso valorativa. Dentre os recursos potencialmente relevantes para o desenvolvimento da EA, destacamos o cinema ficcional e documentrio. Possuidor de uma linguagem prpria, o cinema pode e deve ser utilizado, visto que sua presena na sociedade atual intensa. Dentre as inmeras qualidades que este recurso possui, consideramos que ele apresenta imenso poder de atrair a ateno dos alunos, uma vez que possui por si s tcnicas nicas para tal finalidade. O uso do cinema em sala de aula, entretanto, exige alguns cuidados e preparativos por parte de quem se prope a utiliz-lo com este fim, ou corre-se o risco de recair em um uso corriqueiro, a fins de entretenimento, e portanto sem qualquer finalidade educativa. As perguntas que permeiam o presente trabalho so: este assunto tem sido abordado em teses e dissertaes voltadas a pesquisas envolvendo a EA? Se sim, quais fundamentaes tericas abarcam, e o que est sendo levando em considerao para sua execuo? Que aspectos significativos tm sido apontados sobre esses recursos, que podem subsidiar os trabalhos de EA? Para a coleta das teses de interesse, recorreremos ao banco de dissertaes e teses de educao ambiental desenvolvido pelo projeto de pesquisa interinstitucional denominado Educao ambiental no Brasil: anlise da produo acadmica (teses e dissertaes) - EArte. Verificamos que, apesar de muitos trabalhos apontarem o uso de filmes em suas pesquisas, este uso ainda feito de maneira superficial e tido apenas como mais um recurso de apoio. Existe uma...
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Used as catalysts even in organic and inorganic molecules, as additives on catalysts, electrochromic films on smart windows the tungsten trioxide have been largely studied on the lasts decades, but there is just a few about it's luminescence. Using as precursors nitric acid and sodium tungstate the tungsten trioxide were been prepared thru wet process then treating on thermic and hydrothermal treatments. Where been evaluated the effects of methodology, nitric acid concentration, duration and temperature of treatments. The samples were characterized by X-ray diffraction (XRD), Raman scattering spectroscopy (RSS), Fourier transformed infrared spectroscopy, photoluminescence spectroscopy (PLS) and X-ray excited optical luminescence (XEOL). Hydrated phases of tungsten trioxide were obtained through hydrothermal treatments and the non-hydrated phases occur with thermic treatments. The acid concentration has the ability to determine the major phase formed as well the temperature determine the hydratation of the product. With lower temperatures dihydrate phase were preferable formed and with the rise of temperature, the water molecules were lost up to the fractionary hydratation and then the non-hydrated phase with higher temperatures depending on the atmosphere used on the thermal treatment. Doping the system with europium ions even substituting tungsten or in the interstices of the matrix were not been successful, as well the XEOL spectroscopy intensity were null and quite low for ultraviolet and visible excitation photoluminescence because of oxygen defect levels localized into the prohibited band.