Group theory for structural analysis and lattice vibrations in phosphorene systems

Group theory analysis for two-dimensional elemental systems related to phosphorene is presented, including (i) graphene, silicene, germanene and stanene, (ii) dependence on the number of layers and (iii) two stacking arrangements. Departing from the most symmetric $D_{6h}^{1}$ graphene space group, the structures are found to have a group-subgroup relation, and analysis of the irreducible representations of their lattice vibrations makes it possible to distinguish between the different allotropes. The analysis can be used to study the effect of strain, to understand structural phase transitions, to characterize the number of layers, crystallographic orientation and nonlinear phenomena.Comment: 24 pages, 3 figure

Multiplicação de sequóia (Sequoia sempervirens L.) em meio de cultura esterelizado com hipoclorito de sódio.

O objetivo desta pesquisa foi comparar a eficiência deste protocolo com o protocolo convencional, que utiliza a autoclavagem como método de esterilização, bem como analisar o comportamento de plantas de sequóia em meio de cultura esterilizado com hipoclorito de sódio.Suplemento. Edição dos Resumos do XVI Congresso Brasileiro de Floricultura e Plantas Ornamentais; III Congresso Brasileiro de Cultura de Tecidos e Plantas; I Simpósio de Plantas Ornamentais Nativas, Goiânia, set. 2007

On the dynamics of bubbles in boiling water

We investigate the dynamics of many interacting bubbles in boiling water by using a laser scattering experiment. Specifically, we analyze the temporal variations of a laser intensity signal which passed through a sample of boiling water. Our empirical results indicate that the return interval distribution of the laser signal does not follow an exponential distribution; contrariwise, a heavy-tailed distribution has been found. Additionally, we compare the experimental results with those obtained from a minimalist phenomenological model, finding a good agreement.Comment: Accepted for publication in Chaos, Solitons & Fractal

Simulation of biomass gasification in circulating fluidized bed reactor by aspen plus

Biomass is the fourth largest source of energy in the world. Many consider it to be the best option, with the greatest potential as an alternative energy supply which meets energy requiremen ts, for ensuring future fuel supply. Biomass energy resources are potentially the world's largest and most sustainable energy source, a renewable resource comprising 220 billion oven-dry tons (about 4500 EJ) of annual primary production [1]. lt is currently assumed that 5% of this energy could be mobilized to produce energy, i.e. a total of 225 EJ representing an energy equivalent ofmore than 5 billion tons ofoil equivalent, accounting for almost 50% ofthe world's total primary energy demand at present [2]. Hydrogen production is one of the most promising alternative energy technologies . The majority of experts consider that hydrogen has a significant role to play as an important energy carrier in the future energy sector [3]. Howe ver, it is a secondary form of energy that, like electricity, must be manufactured. A promising way to generate hydrogen is by thermochemical conversion of biom ass to synthe sis gas , consisting of a mixture of H2, CO, C0 2, CH.i, 0 2, N2 and tar. ln order to maximize H2 yield, an Or steam circulating fluidized bed (CFB) gasification process was proposed. For this purpose a computer simulation model was developed using the commercial chemical process simulator ASPEN Plus.N/

Desempenho produtivo de oito clones de cajueiro anão precoce cultivados no semi-árido piauiense sob regime de sequeiro.

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Comportamento produtivo de oito clones de cajueiro-anão-precoce em cultivo de terceiro ano sob regime de sequeiro.

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Avaliação de clones de cajueiro-anão-precoce em cultivo de terceiro ano no semi-árido piauiense.

O objetivo deste trabalho foi avaliar o desempenho produtivo de oito clones de cajueiro anão precoce no semi-árido piauiense, visando identificar os mais promissores para a produção de castanha e caju para mesa..

Avaliação de clones de cajueiro-anão-precoce no cerrado do sul maranhense.

Avaliação de Clones de Cajueiro-Anão-Precoce no Cerrado do Sul Maranhense; Introdução; Desenvolvimento; Biometria; Produtividade; Características do fruto; Aptidão comercial; Distribuição média mensal da produção de castanha; Características agroeconômicas; Comercialização da produção; Comparativos econômicos.bitstream/item/37219/1/Doc145.pd