875 resultados para Rosal, Miguel Angel


Relevância:

80.00% 80.00%

Publicador:

Resumo:

Incluye Bibliografía

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This paper introduces an indirect estimate for the coefficients of distribution, hydrodynamic dispersion and retardation for contaminants commonly encountered in sanitary landfills and their liners, such as Cu2+ and K+; this estimate is based on the relationship between concentration and certain physical characteristics of typical Brazilian soils. The results of previous studies investigating the migration of contaminants were used to develop mathematical expressions from multiple non-linear regressions. Using minimal squares regression, this transport was linked to various combinations of contaminant concentration and both structural and textural characteristics of the porous medium. Various combinations of characteristics and concentrations were investigated, with a mathematical expression obtained for each. The relationship between percentage of clay and the contaminant content proved to be the most closely correlated with actual transport parameters, with coefficients close to one.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Incluye Bibliografía

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Incluye Bibliografía

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Includes bibliography

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The effect of seed addition on the microstructure and non-ohmic properties of the SnO2 + 1%CoO + 0.05%Nb2O5 ceramic-based system was analyzed. Two classes of seeds were prepared: 99% SnO2 + 1%CuO and 99% SnO2 + 1%CoO (mol%); both classes were added to the ceramic-based system in the amount of 1%, 5%, and 10%. The two systems containing 1% of seeds resulted in a larger grain size and a lower breakdown voltage. The addition of 1% copper seeds produces a breakdown voltage (V b) of ∼ 37 V and a leakage current (fic) of 29 μA. On the other hand, the addition of 1% cobalt seeds produced a breakdown voltage of 57 V and a leakage current of 70 μA. Both systems are of great technological interest for low voltage varistor applications, by means of appropriate strategies to reduce the leakage current. Using larger amounts of seeds was not effective since the values of breakdown voltage in both cases are close to a system without seeds. To our knowledge, there are no reports in the literature regarding the use of seeds in the SnO2 system for low voltage applications. A potential barrier model which illustrates the formation of oxygen species (O′2(ads), O′ads, and O″ads) at the expense of clusters near the interface between grains is proposed. © 2012 The American Ceramic Society.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The Copaiba oil has been used as an auxiliary treatment of inflammations, skin disorders and stomach ulcers, however, in dentistry, this alternative medicine has not been investigated yet. The purpose of this study was to evaluate the influence of topic and systemic administration of copaiba oil on the alveolar wound healing after tooth extraction. Twenty-eight wistar male rats had their lower first molar teeth extracted. Subsequently, they were divided in four groups, according to the treatment performed: (a) alveolar socket irrigation with copaiba oil; (b) alveolar socket irrigation with physiological serum; (c) daily gavage with copaiba oil or (d) daily gavage with physiological serum. After the sacrifice, the mandibles were removed and processed in order to obtain decalcified histological sections. The results demonstrated high level of epithelial migration, small number of inflammatory cells and vascular enhancement in the animals which received systemic administration of copaiba oil. The rats treated with topic administration of copaiba oil presented ulcerations and large number of inflammatory cells. An increased bone neoformation was observed in both groups treated with copaiba oil when compared with placebo group. It could be concluded that topic or systemic administration of copaiba oil leads to a better alveolar bone healing, however the topic application on connective tissue should be carefully considered, regarding the whole socket wound healing. © Medicina Oral S. L. C.I.F. B 96689336 - eISSN: 1989-5488.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Incluye Bibliografía

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Incluye Bibliografía

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Incluye Bibliografía

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Incluye Bibliografía

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Incluye Bibliografía