Caracterização do óleo de pinhão-manso (Jatropha curcas L.).

O pinhão manso (Jatropha curcas L.), pertencente a familia Euphorbiaceae, e uma planta nativa da America tropical, naturalizada em partes tropicais e subtropicais da Africa e Asia. Sua distribuição geografica e bastante vasta devido a sua rusticidade, resistencia a longas estiagens, bem como a pragas e doencas, sendo adaptavel a condicoes edafoclimaticas muito variaveis. O fruto de J.curcas contem oleo viscoso que pode ser usado na industria de cosmeticos, como substituto do querosene, e na fabricacao de sabao e combustivel para motores diesel. Este trabalho tem como objetivo caracterizar o oleo de pinhao manso segundo sua composicao quimica e parâmetros fisico-quimicos, tendo em vista sua utilizacao para a producao de biocombustivel..

Invasion Percolation Between two Sites

We investigate the process of invasion percolation between two sites (injection and extraction sites) separated by a distance r in two-dimensional lattices of size L. Our results for the non-trapping invasion percolation model indicate that the statistics of the mass of invaded clusters is significantly dependent on the local occupation probability (pressure) Pe at the extraction site. For Pe=0, we show that the mass distribution of invaded clusters P(M) follows a power-law P(M) ~ M^{-\alpha} for intermediate values of the mass M, with an exponent \alpha=1.39. When the local pressure is set to Pe=Pc, where Pc corresponds to the site percolation threshold of the lattice topology, the distribution P(M) still displays a scaling region, but with an exponent \alpha=1.02. This last behavior is consistent with previous results for the cluster statistics in standard percolation. In spite of these discrepancies, the results of our simulations indicate that the fractal dimension of the invaded cluster does not depends significantly on the local pressure Pe and it is consistent with the fractal dimension values reported for standard invasion percolation. Finally, we perform extensive numerical simulations to determine the effect of the lattice borders on the statistics of the invaded clusters and also to characterize the self-organized critical behavior of the invasion percolation process.Comment: 7 pages, 11 figures, submited for PR

Screening effects in flow through rough channels

A surprising similarity is found between the distribution of hydrodynamic stress on the wall of an irregular channel and the distribution of flux from a purely Laplacian field on the same geometry. This finding is a direct outcome from numerical simulations of the Navier-Stokes equations for flow at low Reynolds numbers in two-dimensional channels with rough walls presenting either deterministic or random self-similar geometries. For high Reynolds numbers, when inertial effects become relevant, the distribution of wall stresses on deterministic and random fractal rough channels becomes substantially dependent on the microscopic details of the walls geometry. In addition, we find that, while the permeability of the random channel follows the usual decrease with Reynolds, our results indicate an unexpected permeability increase for the deterministic case, i.e., ``the rougher the better''. We show that this complex behavior is closely related with the presence and relative intensity of recirculation zones in the reentrant regions of the rough channel.Comment: 4 pages, 5 figure

Gravity with extra dimensions and dark matter interpretation: Phenomenological example via Miyamoto-Nagai galaxy

A configuration whose density profile coincides with the Newtonian potential for spiral galaxies is constructed from a 4D isotropic metric plus extra dimensional components. A Miyamoto-Nagai ansatz is used to solve Einstein equations. The stable rotation curves of such system are computed and, without fitting techniques, we recover with accuracy the observational data for flat or not asymptotically flat galaxy rotation curves. The density profiles are reconstructed and compared to that obtained from the Newtonian potential.Comment: 10 pages, 10 figures, submitted to Brazilian Journal of Physic

Soil microbial properties and temporal stability in degraded and restored lands of Northeast Brazil.

Human activities, such as land use change, cause severe land degradation in many ecosystems around the globe with potential impacts on soil processes. Restoration practices aim at reverting such impacts and reconstituting the biotic composition and functioning of an ecosystem to its initial condition. The aim of this study was to monitor soil microbial properties in degraded lands in Northeast Brazil and to compare those with land under restoration. Soil samplings were conducted in 2009, 2010 and 2011 in two different seasons (wet and dry season) at sites differing in degradation status: native vegetation (NAT), moderately degraded land (MDL), highly degraded land (HDL), and land under restoration for four years (RES). Soil microbial properties showed pronounced fluctuations between seasons with higher levels of functioning in the wet than in the dry season. Soil microbial biomass and enzymes had significantly higher values under native vegetation than in degraded land, while restored land mostly corresponded to native vegetation. Soil microbial biomass, respiratory quotient and enzyme activities were more strongly affected by land degradation than soil chemical properties

Avaliação do rendimento de raízes de diferentes genótipos de mandioca brava (Manihot esculenta, Crantz).

O potencial de capacidade de produção máximo de mandioca é estimado em condições ótimas, através de modelos matemáticos de crescimento, preveem que bons genótipos possam produzir até 90 t/ha/ano de raízes ou 30 t/ha/ano de matéria seca. As cascas constituem cerca de 20-35% do peso do tubérculo, especialmente no caso da má descamação (Obadina, 2006). Os teores de matéria seca nas raízes são altamente correlacionados com os teores de amido ou fécula, dependendo da variedade do local onde se cultiva, sua idade e época de colheita. Assim, objetivou-se avaliar o rendimento de polpa fresca, de amido total, massa seca de amido e umidade de 15 genótipos de mandioca brava (Manihot esculenta, Crantz), pertencente ao banco ativo de germoplasma (BAG) da Embrapa Amazônia Oriental localizada em Belém do Pará. A média percentual dos genótipos de mandioca para polpa fresca variou de (62,39% a 83,95%), do amido total extraído variou de (8,80% a 33,17%) e da massa seca do amido foi de (66,83% a 91,20%). Portanto, as caracterizações de os materiais genéticos auxiliarão ao programa de melhoramento genético da Embrapa Amazônia Oriental

Parâmetros genéticos da produção de leite em búfalos (Bubalus bubalis) por regressão aleatória de acordo com a ordem dos partos na Amazônia Oriental.

ZOOTEC 2009