Influência do sistema de produção sobre a formação de osteodermos no couro em jacaré do Pantanal (Caiman yacare, Daudin).

Com o objetivo de identificar a influência do sistema de criação na acumulação de cálcio no interior do couro de jacaré do Pantanal, foram obtidos dez animais de cada um dos criatórios situados em Cáceres, MT: Coocrijapan, Jacarepan e Aguacerito. Após o abate e a esfola, as peles foram conservadas por salmouragem e salga, embaladas em sacos de polipropileno e armazenadas em refrigerador a zero grau Celcius. O curtimento foi realizado após o alvejamento e abrandamento dos osteodermos. Foram retiradas amostras do centro da região dorsal dos couros e preparadas para análise em microscopia eletrônica de varredura. As eletromicrografias indicaram remanescentes de estruturas ósseas atacadas por produtos químicos descalcificantes, apresentando vários espaços vazios. Tais estruturas encontram-se envoltas por rede de feixes de fibras de colágeno, formando a derme superior e inferior, e ocupam, aproximadamente, metade da espessura total do couro. Os osteodermos das peles dos animais do criatório Coocrijapan foram mais facilmente atacados quimicamente e resultaram em couros mais macios quando comparados com os couros dos animais dos criatórios Jacarepan e Aguacerito. O sistema de criação adotado pelos criatórios comerciais interfere na formação de cálcio no interior das peles, resultando em peles com osteodermos mais ou menos suscetíveis ao ataque químico e, conseqüentemente, couros com diferentes graus de maciez

Dispersion force for materials relevant for micro and nanodevices fabrication

The dispersion (van der Waals and Casimir) force between two semi-spaces are calculated using the Lifshitz theory for different materials relevant for micro and nanodevices fabrication, namely, gold, silicon, gallium arsenide, diamond and two types of diamond-like carbon (DLC), silicon carbide, silicon nitride and silicon dioxide. The calculations were performed using recent experimental optical data available in the literature, usually ranging from the far infrared up to the extreme ultraviolet bands of the electromagnetic spectrum. The results are presented in the form of a correction factor to the Casimir force predicted between perfect conductors, for the separation between the semi-spaces varying from 1 nanometre up to 1 micrometre. The relative importance of the contributions to the dispersion force of the optical properties in different spectral ranges is analyzed. The role of the temperature for semiconductors and insulators is also addressed. The results are meant to be useful for the estimation of the impact of the Casimir and van der Waals forces on the operational parameters of micro and nanodevices

Avaliação de genótipos de feijão-caupi de porte ereto e semi-ereto em Aquidauana, MS.

O objetivo do trabalho foi o de identificar aqueles com potencial para serem recomendados para cultivo na região..

Gel beads from novel ionic polysaccharides

Stable gelling systems were obtained by mixing polyanion solutions with solutions containing suitable polycations. Carboxymethyl cellulose was chosen as the polyanion, whilst a number of polycations, with different molecular weights and charge densities, were tested. In particular, both low molecular weight polyamines and new synthetically aminated polysaccharides, derived from pullulan and scleroglucan, were used. Stable gels, in the absence of phase separation, were obtained only with flexible polycationic species. The morphological characterisation of the gel beads obtained were studied by scanning electron microscopy and NMR microscopy

Influence of water on the physical properties of fluoride glass

Several physical properties of ZBLAN glass, including their characteristic transformation temperatures, density, refractive index and ultrasonic velocity, were studied as a function of their residual water content. A series of samples with OH concentrations up to ∼ 0.0043 mol dm-3 was prepared. The OH content was determined for the partially hydrated glasses from FTIR measurements, using a known molar extinction coefficient value for the 2.9 μm band, assigned to fundamental OH stretching vibrations in Zr{single bond}OH species. Molecular H2O was not found at the present levels of water concentration. The preliminary results obtained indicate that an increase in the OH concentration causes a decrease of the density and refractive index values, similar to what has been observed in v-SiO2, as opposed to the case of silicate glasses. This behavior was not expected, since ZBLAN glass has a complex structure closer to that of modified silicates than to v-SiO2. The effect of the OH concentration on the other physical properties was generally found to coincide with known trends for silicate glasses. © 1992 Elsevier Science Publishers B.V. All rights reserved