Amorphous Oxides
Mostrando 13-22 de 22 artigos, teses e dissertações.
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13. Determinação de cobre, alumínio e ferro em solos derivados do basalto através de extrações seqüenciais
Copper, aluminum and iron concentrations were determined in four geochemical fractions of three different basaltic soils from the northwest region of the Parana State, Brazil. The fractions examined were the reducible manganese dioxide and amorphous iron oxide, crystaline iron oxide, organic and residual. Metal concentrations were determined in the extracts
Química Nova. Publicado em: 2002-07
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14. Preparation and Characterization of Hydrous Zirconium Oxide Formed by Homogeneous Precipitation
This paper reports on the preparation, characterization and study of the ion exchange behavior of hydrous zirconium oxides formed by homogeneous precipitation from zirconium oxychloride. The precipitants used were obtained by thermal decomposition of urea, sodium nitrite or ammonium carbonate. Seven compounds were prepared and characterized by thermal analys
Materials Research. Publicado em: 2002-06
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15. Análise por difração de raios x de filmes de óxidos cerâmicos compostos por IrO2/TiO2/CeO2
Independent of the sample form (powder or film), XRD analysis of Ir0,3Ti(0,7-x)Ce xO2, (nominal) mixtures, for x=0, shows the formation of a solid solution phase between IrO2 and TiO2, as well as the rutile phases of IrO2 and TiO2. The presence of the anatase phase of TiO2 is also confirmed. The introduction of 30 mol% CeO2 in the mixture reveals the presenc
Química Nova. Publicado em: 2000-10
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16. Hibridos lamelares e hexagonais envolvendo silicio, aluminio, zirconio e titanio
By using tetraethylortosilicate, amorphous silica-gel, tetrabutoxyde of aluminium, zirconium and titanium, as well as n-alkyldiamnines as precursors, a series of twenty nine inorganic-organic hybrid materiais, with lamellar or hexagonal structures were synthesized. Is shown that lamellar silica samples can be sucessfully used as sequestrating agents for tran
Publicado em: 2000
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17. Electrical conductivity of borate, silicate and silica-sulphate glasses of alkaline ions. / Condutividade elétrica de vidros de boratos, silicatos e sílico-sulfatos de íons alcalinos.
Conducting glasses based on borates, silicates and silica-sulfates of alkali metals have been prepared from an appropriate mixture of powder of oxides, carbonates and sulfates. They were produced by fusion in a silicon carbide furnace up to 1400ºC and then by fast cooling. These materials have been analyzed with techniques of DC conductivity and Impedan
Publicado em: 2000
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18. Acoplamento oxidativo de metano sobre catalisadores Li-Mn/MgO-SiO2
Oxidative coupling of methane is an alternative route for the conversion of methane to hydrocarbons of higher molecular mass and higher boiling points. This reaction has received considerable scientific and industrial attention over the past 20 years. In this work 17 samples of Li-Mn/MgO-Si O IND. 2 were prepared and tested in the oxidative coupling of metha
Publicado em: 1999
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19. Neutrophilic Fe-Oxidizing Bacteria Are Abundant at the Loihi Seamount Hydrothermal Vents and Play a Major Role in Fe Oxide Deposition
A number of hydrothermal vent sites exist on the summit of the Loihi Seamount, a shield volcano that is part of the Hawaiian archipelago. The vents are 1,100 to 1,325 m below the surface and range in temperature from slightly above ambient (10°C) to high temperature (167°C). The vent fluid is characterized by high concentrations of CO2 (up to 17 mM) and Fe
American Society for Microbiology.
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20. Production of Biogenic Mn Oxides by Leptothrix discophora SS-1 in a Chemically Defined Growth Medium and Evaluation of Their Pb Adsorption Characteristics
Biogenic Mn oxides were produced by the bacterium Leptothrix discophora SS-1 (= ATCC 3182) in a chemically defined mineral salts medium, and the Pb binding and specific surface area of these oxides were characterized. Growth of SS-1 in the defined medium with pyruvate as a carbon and energy source required the addition of vitamin B12. Complete oxidation of M
American Society for Microbiology.
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21. Evidence for microbial iron reduction in a landfill leachate-polluted aquifer (Vejen, Denmark).
Aquifer sediment samples obtained from the anaerobic part of a landfill leachate plume in Vejen, Denmark, were suspended in groundwater or in an artificial medium and incubated. The strictly anaerobic suspensions were tested for reduction of ferric iron [Fe(III)] oxides, which was measured as an increase in the concentration of dissolved Fe(II). Iron reducti
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22. Diversion of Electron Flow from Methanogenesis to Crystalline Fe(III) Oxide Reduction in Carbon-Limited Cultures of Wetland Sediment Microorganisms
Electron flow in acetate-limited cultures of wetland sediment microorganisms was diverted from methane production to Fe(III) reduction in the presence of crystalline Fe(III) oxides at surface area loadings equivalent to that of amorphous Fe(III) oxide. The results indicate that inferences regarding the ability of microbial Fe(III) oxide reduction to compete
American Society for Microbiology.