907 resultados para Reacções de redução


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Pós-graduação em Química - IQ

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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O sociólogo brasileiro Alberto Guerreiro Ramos elaborou, no final da década de 1950, uma construção metodológica voltada para a recepção crítica das idéias importadas que apontava para a criação de uma sociologia nacional, projeto singular e confluente ao do desenvolvimentismo de um capitalismo nacional no Brasil.

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Descrito como o presente Privilégio de Invenção, refere-se a um processo para a desinfecção de superfícies condutoras ou semicondutoras, evitando a formação ou eliminando biofilmes preexistentes, para tanto, o presente processo é realizado por meio da aplicação de um potencial ou corrente elétricos sobre as referidas superfícies sendo vantajosa por dispensar o uso de agentes biocidas, bem como não necessitar do uso de materiais ou produtos abrasivos, ou seja, com a tecnologia proposta no presente processo é possível controlar ou eliminar a presença de biofilmes em sistema industriais sem adição de substâncias ao sistema, pois no presente processo o reagente é o elétron ou o campo elétrico formado por ele.

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Contamination of Brazilian sugar-cane rum by ethyl carbamate, a potentially carcinogenic substance, is considered an obstacle to export of the beverage. Copper is involved in ethyl-carbamate-formation reactions, and the replacement thereof by stainless steel in distillation equipment, with the aim of preventing the formation of said compound, results in a beverage of poor sensory quality owing to the presence of dimethyl sulphide. A reduction in the concentration of sulphurated compounds in the final product may be achieved by the placing of a copper device (Patent No. 8206688) inside the dome of a stainless-steel alembic. It is therefore appropriate to verify the efficiency of using other forms of catalysts that, in addition to reducing ethyl-carbamate levels, are able, likewise, to trigger other catalytic actions that allow the production of a distillate of good sensory quality. Silver is the noble metal most used in industry and, on account of the catalytic properties thereof, it is ideal for use as a catalyst in oxidation reactions. The subject matter of the present invention comprises a method involving the use of silver in the distillation of alcoholic beverages, such as sugar-cane rum, which reduces ethyl-carbamate contamination of the end-product.

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The chemical control of the causal agent of citrus black spot (CBS) has been highlighted for the excessive required number of sprayings, considerably increasing citrus production costs. Improvements in the spray efficiency and reductions in the quantity of phytosanitary products have already been searched, but the results of that practice are not consistent yet for its use at commercial scale. Thus, the aim of the present study was to evaluate the interference of reduced spray volumes in black spot control in citrus fruits. The experiment was carried out in commercial citrus orchard with 16-year-old plants of 'Valencia' variety, during 2007 agricultural season. Treatments consisted of three spray volumes: 3.5; 4.5 and 8.5 liters.plant-1, applied with Arbus 2000/Export airblast sprayer with special manifold of hydraulic nozzles, using fungicides and periods recommended for the disease control, totaling four sprayings plus a control treatment (without spray). The disease incidence and severity were evaluated by visual diagrammatic scale of notes in two different periods (preharvest and harvest), at three plant heights (low, middle and top) and three horizontal sections (entrance, frontal and exit) in two sides of the plant. The fallen fruits were counted every fifteen days, for previously selected plants, from the beginning of maturation to harvest, and the production was quantified (kg.plant-1). The disease incidence and severity were significantly lower when sprayings were done with 8.5 liters.plant-1 in the first evaluation period (pre-harvest), but in the harvest period there were not differences between the same parameters when 4.5 or 8.5 liters.plant-1 were sprayed. None of those treatments reduced the disease on the top section of plants, compared to control. The plant sections with fruits more exposed to sun rays, top and right side of the plant, demonstrated higher disease incidence and severity. The volume reduction from 8.5 to 4.5 liters.plant-1 can be adopted for citrus orchards without damaging the CBS control level.

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Pós-graduação em Aquicultura - FCAV

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Pós-graduação em Biotecnologia - IQ

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Engenharia Elétrica - FEIS