[en] In the present work it has been studied the microstructure and the mechanical behaviour of a materials produced by rheocasting, a new semisolid industrial process which introduces important improvements in comparison to conventional routes. the microstructure of the A357 hypoeutectic Al-Si alloys has been analysed before and after material injection. In both cases the microstructure was fine and homogeneous. Tensile tests have been done with specimens machined from real rheocasted components in two conditions, without any heat treatment and after T5 heat treatment. The results were found to be better than those obtained for this alloy when produced by conventional means. (Author) 20 refs

[en] A 15-year-old girl with a limp and weakness and wasting of the left leg, was found to have a large chondromyxoid fibroma of the sacrum. The lesion presented difficulties in diagnosis because of its unusual site, neurological presentation, large size and extensive extension into the soft tissues of the pelvis and buttock. (orig.)

[en] The imaging findings of a 3 year old girl with a mild form of holoprosencephaly is presented. axial and sagittal magnetic resonance imaging demonstrated several abnormalities including the absence of interhemispheric fissure and fusion between cerebral hemispheres. 34 refs., 1 fig

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[en] The objective of this work is to study the environment contamination by mercury in the current sediments and alluvial plain sediments in the course of Muriaé River (between towns of Patrocinio de Muriaé (MG) – Itaperuna (RJ)) in Minas Gerais and Rio de Janeiro States where occurred the extraction of gold using the process of amalgamation by mercury during eighties and the beginning of the nineties. The methodology used was based in total and sequential extraction. The results in parts per billion (ng.g-1) showed that the total mercury ranged from 222,9 to 761,9 ng.g-1 in the current sediments et 233,6 to 2131,9 ng.g-1 in the alluvial plain sediments. Comparing theses values with the background of region (170 ng.g-1 to 365 ng.g-1) only two of the samples showed results according to this background. The others showed results above this interval. It was observed that when it comes to the availability of mercury to the aquatic environment and biota, 1% to 26,2% of the total mercury is in the exchangeable phase, easily available for the environment, 52,3% to 90,4 % is potentially available (in the oxidizable phase) and 0,2 % to 40 % is inert, imprisoned in the mineral's structure of the sediments ( residual phase)

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[en] Graphene oxide (GO) is one of the main precursors for the production of graphene and other graphene-based materials. We report a simple, safe, and fast synthesis method to obtain graphene oxide as a functional material for battery-type electrodes. Washing and lyophilization processes were performed to evaluate their effects on exfoliation and removal of functional groups from graphene sheets. Sample GO1 consisted of a 10-layer stack of oxidized graphene, while sample GO2 had 8 stacked layers. The difference between them was an extra washing and lyophilization process in the GO2 sample. The electrochemical performance of graphene oxide-based electrodes, classified as battery-type, indicated an improved specific capacity of 10.15 C.g^-1 for O1 against 4.55 C.g^-1 for GO2 at a specific current of 0.5 A.g^-1. This superior battery-type behavior of the GO1 electrode, also confirmed by electrochemical impedance spectroscopy, was most likely due to a higher degree of oxygenated groups on its surface, as shown by energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) studies. (author)

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[en] Full text. As alternatives to black holes, gravastars have received some attention recently, partially due to the tight connection between the cosmological constant and a currently accelerating universe. Here we constructed some dynamical models of prototype gravastars, in which an infinitely thin spherical shell of a perfect fluid with the equation of state p = (1 - γ)σ divides the whole spacetime into two regions, the internal region is filled with a dark energy fluid, characterized by a positive cosmological constant, as in the original Mazur and Motolla model, or by a more general anisotropic dark energy fluid, and tthe external Schwarzschild region. We analyse the possibilities of formation of a stable structure and it was found that, for both inner fluids, in some cases the models represent the 'bounded excursion' stable gravastars, where the thin shell is oscillating between two finite radii, while in other cases they collapse until the formation of black holes or normal stars. In the phase space, the region for the 'bounded excursion' gravastars is very small in comparison to that of black holes, but not empty. Therefore, although the existence of gravastars can not be completely excluded from current analysis, the opposite is not possible either, that is, even if gravastars exist, they do not exclude the existence of black holes. (author)