Características agronômicas, botânicas, e fenológicas de genótipos de arroz-vermelho.

O objetivo deste trabalho foi apresentar algumas informações sobre os genótipos de arroz-vermelho coletados em regiões brasileiras

Caracterização morfoagronômica e fenológica de acessos da coleção de arroz da Embrapa Arroz e Feijão.

O objetivo deste trabalho foi estudar as características morfoagronômicas e fenológicas de acessos de arroz-cateto coletados em regiões de cultivo no país

Atividades do banco ativo de germoplasma de feijoeiro comum (Phaseolus vulgaris L.) da Embrapa.

O Banco Ativo de Germoplasma de Feijão, em parceria com a Embrapa Recursos Genéticos e Biotecnologia, tem contribuído com a comunidade científica através do enriquecimento da variabilidade genética, disponibilizando mais de 14.000 acessos, com mais de 29.000 amostras distribuídas entre a comunidade científica em geral, o que evidencia a preocupação com problemas como a fome e o desenvolvimento de uma agricultura sustentável

Características do germoplasma de feijão (Phaseolus vulgaris L.) coletado na região litorânea do Rio Grande do Sul.

O objetivo desse trabalho foi apresentar informações sobre cor, tamanho e brilho das sementes das variedades usadas pelos agricultores da região litorânea do Rio Grande do Sul

Mineral content in French type bread with sodium replacement using fluorescence spectrometry X-rays by energy dispersive

The present study aimed to determine the mineral composition of the French type bread with partial replacement of sodium chloride by potassium chloride using the technique of X-ray fluorescence energy dispersive. The excitation energy used was 50 keV and detector operation at -176°C. The detected variations were from 10.16 to 613.69 mg 100 g-1 for sodium and from 211.58 to 958.96 mg 100 g-1 for potassium. The concentrations of iron, magnesium, phosphorus and calcium ranged from 10.62 to 21.45, 16.59 to 30.78, 92.53 to 125.77 and from 16.54 to 100.88 mg 100 g-1, respectively. The use of this simple technique proved to be reliable on detecting the variations imposed on the French type bread formulation. The results of this study indicate that, at the levels studied, the addition of potassium chloride assisted in getting French type bread with lower levels of sodium and proved the technological feasibility of producing French type bread with 43% salt reduction (1.0% in the commercial formulation) with 0.5% potassium chloride, which provide bread with the amount of sodium proposed to meet the set limits (174.09 mg.50 g-1), related to the salt standard formulation of 1.88% (306.5 mg.50 g-1).Key words: French bread, replacement, sodium chloride, potassium chloride, food analysis, minerals, energy dispersive

Electronic and phononic states of the Holstein-Hubbard dimer of variable length

We consider a model Hamiltonian for a dimer including all the electronic one- and two-body terms consistent with a single orbital per site, a free Einstein phonon term, and an electron-phonon coupling of the Holstein type. The bare electronic interaction parameters were evaluated in terms of Wannier functions built from Gaussian atomic orbitals. An effective polaronic Hamiltonian was obtained by an unrestricted displaced-oscillator transformation, followed by evaluation of the phononic terms over a squeezed-phonon variational wave function. For the cases of quarter-filled and half-filled orbital, and over a range of dimer length values, the ground state was identified by simultaneously and independently optimizing the orbital shape, the phonon displacement and the squeezing effect strength. As the dimer length varies, we generally find discontinuous changes of both electronic and phononic states, accompanied by an appreciable renormalization of the effective electronic interactions across the transitions, due to the equilibrium shape of the wave functions strongly depending on the phononic regime and on the type of ground state.Comment: 11 pages, RevTeX, 10 PostScript figures; to appear in Phys. Rev.

Effect of band filling in the Kondo lattice: A mean-field approach

The usual Kondo-lattice, including an antiferromagnetic exchange interaction between nearest-neighboring localized spins, is treated here in a mean-field scheme that introduces two mean-field parameters: one associated with the local Kondo effect, and the other related to the magnetic correlations between localized spins. Phases with short-range magnetic correlations or coexistence between those and the Kondo effect are obtained. By varying the number of electrons in the conduction band, we notice that the Kondo effect tends to be suppressed away from half filling, while magnetic correlations can survive if the Heisenberg coupling is strong enough. An enhanced linear coefficient of the specific heat is obtained at low temperatures in the metallic state.Comment: 7 pages, ReVTeX two-column, 7 figure