Relação entre temperatura de pirólise e a porosidade do mesocarpo de frutos da castanheira-do-Brasil.

A casca dos frutos de castanhado-Brasil (Bertholletia excelsa) é um resíduo abundante, mas praticamente sem aproveitamento nas regiões extrativistas da Amazônia. Sendo assim, trata-se de uma matéria-prima com potencial para a produção de carvão para uso agronômico. Neste trabalho, avalia-se por meio de imagens de microscopia eletrônica de varredura o desenvolvimento da porosidade em carvões obtidos a partir das cascas dos frutos de castanheira-do-Brasil pirolisadas a 350, 450 e 550°C. Devido às particularidades morfológicas deste tecido vegetal, a porosidade do carvão aumenta com a temperatura, independente da fração granulométrica analisada

Relação entre temperatura de pirólise e a porosidade do mesocarpo de frutos da castanheira-do-Brasil.

A casca dos frutos de castanhado-Brasil (Bertholletia excelsa) é um resíduo abundante, mas praticamente sem aproveitamento nas regiões extrativistas da Amazônia. Sendo assim, trata-se de uma matéria-prima com potencial para a produção de carvão para uso agronômico. Neste trabalho, avalia-se por meio de imagens de microscopia eletrônica de varredura o desenvolvimento da porosidade em carvões obtidos a partir das cascas dos frutos de castanheira-do-Brasil pirolisadas a 350, 450 e 550°C. Devido às particularidades morfológicas deste tecido vegetal, a porosidade do carvão aumenta com a temperatura, independente da fração granulométrica analisada

Integrated soil degradation analysis of tierra de Barros region (Badajoz, Spain).

This study assesses the soil degradalion in Tierra de Barros region (Badajoz province, Spain (280.900 ha). The sludy emphasizes on lhe soil susceptibilily to sealing and crusting, compactation and soilloss by water erosion

Random amplified polymorphic DNA analysis of effective Rhizobium sp. associated with beans cultivated in Brazilian cerrado soils.

Efficient bean nodulating Rhizobium strains, isolated from different Brazilian cerrado soils, were characterized by RAPD. This study showed great genetic heterogeneity among R. tropici and R. leguminosarum bv. phaseoli strains and allowed the constitution of genetic clusters, besides indicating the most suitable primers for this characterization. The groups of genetically distinct strains can be used in competitiveness studies to select appropriate Rhizobium strains for bean inoculation in cerrado soils

Estrutura genética do pirarucu (Arapaima gigas) na região de Santarém, PA, Brasil.

O pirarucu (Arapaima gigas) é um peixe encontrado na Bacia Amazônica e Araguaia/Tocantins que possui grande importância econômica para populações locais. Estudos para avaliação da estrutura genética das populações naturais de pirarucu são necessários a fim de prover informações para o manejo da espécie em seu habitat natural. Desta forma, este trabalho analisou quatro comunidades próximas à região de Santarém-PA (N=99) por meio do sequenciamento de 1059 pb do gene mitocondrial ATPase. Os resultados sugerem que a variabilidade genética encontrada é similar a encontrada em estudos de maior abrangência geográfica. A rede de haplótipos gerada, mostrou dois haplogrupos dentro dos quais estão distribuídos cinco haplótipos (H) referentes a este estudo distribuídos de forma semelhante à rede haplotípica disponibilizada na literatura

Ab initio study on the magneto-structural properties of MnAs

The magnetic and structural properties of MnAs are studied with ab initio methods, and by mapping total energies onto a Heisenberg model. The stability of the different phases is found to depend mainly on the volume and on the amount of magnetic order, confirming previous experimental findings and phenomenological models. It is generally found that for large lattice constants the ferromagnetic state is favored, whereas for small lattice constants different antiferromagnetic states can be stabilized. In the ferromagnetic state the structure with minimal energy is always hexagonal, whereas it becomes orthorhombically distorted if there is an antiferromagnetic component in the hexagonal plane. For the paramagnetic state the stable cell is found to be orthorhombic up to a critical lattice constant of about 3.7 Angstrom, above which it remains hexagonal. This leads to the second order structural phase transition between paramagnetic states at about 400 K, where the lattice parameter increases above this critical value with rising temperature due to the thermal expansion. For the paramagnetic state an analytic approximation for the magnitude of the orthorhombic distortion as a function of the lattice constant is given. Within the mean field approximation the dependence of the Curie temperature on the volume and on the orthorhombic distortion is calculated. For orthorhombically distorted cells the Curie temperature is much smaller than for hexagonal cells. This is mainly due to the fact that some of the exchange coupling constants in the hexagonal plane become negative for distorted cells. With these results a description of the susceptibility as function of temperature is given

Fertbrasil: an innovative network for the development of tropical soils fertilizers.

This paper aims to present the FertBrasil network, a network leaded by the Brazilian Agricultural Research Corporation ? Embrapa, that includes more than three hundreds of researchers in more than fifty institutions, among public agents, universities and private companies. First, we introduce the subject of network innovation and a little background on tropical fertilizers. Then, we present the FertBrasil network, since its creation, passing by its leadership, partners and the products the network intends to develop. After, a little is discussed about the innovative control mechanism of the network and the product development flow, as well as the interaction between FertBrasil and other governmental initiatives or public policies about the same subject. At least, we discuss about the results of the network until now, in terms of products, technologies and political impacts and mobilization in fertilizers research for tropical regions. Then, we conclude presenting some challenges for FertBrasil network as well as reinforcing the important role assumed by this network in contributing to Brazil keeps its high position in agricultural production and productivity