Tungsten Oxide
Mostrando 13-24 de 24 artigos, teses e dissertações.
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13. Preparation, structural and electrochemical properties of V2O5-WO3 xerogel composite / Obtenção, caracterização e estudos das propriedades de compósitos formados por xerogéis de pentóxido de vanádio e óxido de tungstênio
Vanadium pentoxide xerogel has a bi-dimensional structure which is suitable for intercalation of a variety of ions, organic compounds, and even polymeric species. In addition, when associated with other metal oxides such as WO3 and MoO3, it presents an important role in catalysis, since the resulting oxides act as promoters in catalytic reduction of the NOx
Publicado em: 2007
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14. Desenvolvimento de catalisadores bifuncionais de óxido de zircônio modificado por óxidos de tungstênio e molibdênio contendo platina para a reação de isomerização de n-parafinas / Development of bifunctional catalysts on zircon oxide modify by tungsten and molybdenum oxides contain platinum for nparaffin isomerization
Bifunctional catalysts based on zircon oxide modified by tungsten (W = 10, 15 and 20 %) and by molybdenum oxide (Mo= 10, 15 e 20 %) containg platinum (Pt = 1%) were prepared by the polymeric precursor method. For comparison, catalysts the tungsten base was also prepared by the impregnation method. After calcinations at 600, 700 and 800 C, the catalysts were
Publicado em: 2007
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15. Avaliação de diversos métodos para remoção da resina remanescente após descolagem de bráquetes ortodônticos.
The purpose of this study was to evaluate the alterations on enamel surface after the use of 5 different techniques to remove remnant resin after bracket debonding. The sample was constituted of 50 human premolars, extracted for orthodontic and periodontal purposes, whose vestibular faces were submitted to surface rugosimetric analysis, carried out at 3 dist
Publicado em: 2006
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16. Modified Electrodes with Tungsten Oxide: Preparation Methods and Analytic Applications / Eletrodos modificados por óxido de tungstênio: Métodos de preparação e aplicações analíticas
Thin films of non-stoichiometric tungsten oxides have been deposited onto glassy carbon surfaces by electrodeposition from acidic W (VI) solutions. At these modified surfaces, rotating disc electrode voltammetric experiments indicated that iodate is electrocatalytically reduced in a mass-transport controlled process. The influence of the film thickness on th
Publicado em: 2006
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17. Caracterização por XPS de filmes passivos formados sobre aços de baixa liga em meio de bicarbonato
Passive films formed in bicarbonate solutions on carbon steel, chromium steel and high speed steel have been characterized by XPS. The passive films formed on chromium and high speed steels showed superior protective properties than those formed on carbon steel. It was confirmed by XPS that the steel composition influences the passive film composition. Chrom
Química Nova. Publicado em: 2005-03
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18. SOLID-SOLID INTERACTIONS STUDY OF MOO3 AND ALUMINAS AND OF WO3 AND ZRO2 / ESTUDO DA REAÇÃO EM ESTADO SÓLIDO ENTRE MOO3 E ALUMINAS E ENTRE WO3 E ZRO2
Mo/Al2O3 and W/ZrO2 systems have been studied in order to verify if the WO3+ZrO2 reaction occurs in solid state, and if the MoO3+Al2O3 reaction also occurs with porous alumina in the solid state. These mixtures were prepared using two Mo and W loadings: 5 and 10 µmolMo/m2 of support alumina and 10 and 16 µmolW/m2 of support zirconia, and they were calcined
Publicado em: 2004
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19. Fotocromismo em filmes finos de óxidos de tungstênio de diferentes composições
Tungsten oxide thin films with three different compositions were deposited by reactive sputtering in an oxygen-argon plasma. In a system composed of a home made photochemical reactor coupled with an optic fiber spectrophotometer, the photochromic effect was studied in these oxide films as function of UV irradiation time, in ethanol, methanol and formaldehyde
Química Nova. Publicado em: 2003-08
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20. Estudo do processo de deposição e propriedades de filmes de oxido de tungstenio obtidos por uma nova tecnicas de deposição / Study of the deposition process of tungsten oxide films obtained by a new deposition technique
This work describes a novel technique for the deposition of tungsten oxide thin films and reports an investigation on their deposition process and properties. The films were obtained in a vacuum deposition chamber fitted with a tungsten filament heated by an ac power supply. Oxygen was admitted into the chamber using mass flow meters. The films were formed o
Publicado em: 2003
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21. Transição de Fase Difusa e Propriedades Dielétricas de Cerâmicas Ferroelétricas de (Pb, Ba)Nb2O6
Tungsten bonze structured lead barium niobate (Pb1-xBa xNb2O6) ferroelectric ceramics were prepared by the conventional mixed oxide method and their dielectric properties were carefully investigated. All studied samples presented elevated values of maximum dielectric constant (epsilon'm) and its corresponding temperature of maximum (Tm) in comparison with pe
Materials Research. Publicado em: 2002-03
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22. DECOMPOSITION OF HYDRAZINE BY TUNGSTEN OXYCARBIDES: THE INFLUENCE OF MACROPOROSITY AND MECHANICAL STRENGTH ON A 2 N MICROTHRUSTER ENGINE
The aim of this work was to prepare tungsten oxycarbides by Temperature Programmed Reaction (TPR), starting with previously molded macroporous tungsten oxide (WO3). The tungsten oxycarbides were prepared by one of two different methods: direct carburization with CH4/H2 to obtain WC or preliminary formation of nitrides with NH3 to obtain W2N, followed by carb
Brazilian Journal of Chemical Engineering. Publicado em: 2001-12
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23. Study of electrical characterization of 2-methyl-9, 10-di(2-naphthyl)anthracene doped with tungsten oxide as hole-transport layer
An efficient p-doped transport layer composed of an ambipolar material, 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) and tungsten oxide (WO3) has been developed. The admittance spectroscopy studies show that the incorporation of WO3 into MADN can greatly improve the hole injection and the conductivity of the device. Moreover, when this p-doped layer was inc
American Institute of Physics.
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24. Lateral interactions at direction-selective striate neurones in the cat demonstrated by local cortical inactivation.
1. Single neurones were recorded with glass-coated tungsten electrodes from area 17 of the cat's visual cortex. The cats were anaesthetized and artificially respirated with a mixture of halothane, nitrous oxide and oxygen. 2. For local cortical inactivation a multibarrel pipette was placed 0.5-2.5 mm posterior (or anterior) to the recording site, at a depth