Beam loading in the nonlinear regime of plasma-based acceleration

A theory that describes how to load negative charge into a nonlinear, three-dimensional plasma wakefield is presented. In this regime, a laser or an electron beam blows out the plasma electrons and creates a nearly spherical ion channel, which is modified by the presence of the beam load. Analytical solutions for the fields and the shape of the ion channel are derived. It is shown that very high beam-loading efficiency can be achieved, while the energy spread of the bunch is conserved. The theoretical results are verified with the Particle-In-Cell code OSIRIS.Comment: 5 pages, 2 figures, to appear in Physical Review Letter

Treatment of chromium(VI) solutions in a pilot-scale bioreactor through a biofilm of arthrobacter viscosus supported on GAC

The aim of this work is to evaluate the applicability of a biofilm to the removal of chromium in solution, at a pilot scale. The effect of the initial concentration of metal on the biosorption behavior of an Arthrobacter viscosus biofilm supported on granular activated carbon, in batch and column essays was also analyzed. Six isotherm equations have been tested in the present study. The best fit was obtained with the Freundlich model. It was observed that as the initial chromium concentration increases, the uptake increases too, but the removal percentage decreases, with values between 95.20% (C0 = 5 mg/l) and 38.28% (C0 = 1000 mg/l). The batch adsorption studies were used to develop a pilot bioreactor able to remove chromium from aqueous solutions. Data obtained in a pilot-scale reactor showed an average removal percentage of 99.9%, during the first 30 days, for the initial concentration of 10 mg/l and an average removal percentage of 72%, for the same period and for the initial concentration of 100 mg/l. Uptake values of 11.35 mg/g and 14.55 mg/g were obtained, respectively, for the initial concentration of 10 and 100 mg/l. The results obtained are very promising and encourage the utilization of this biofilm in environmental applications.FEDERFundação para a Ciência e a Tecnologia (FCT

Coleta de germoplasma do feijoeiro comum (Phaseolus vulgaris L.) no litoral médio e sul do Rio Grande do Sul.

O objetivo deste trabalho é apresentar informações sobre a coleta de feijão realizada em municípios da região do Litoral Médio e Sul do Rio Grande do Sul, sua colonização, métodos de cultivo, metodologia de coleta, tipos de acessos coletados e futuras avaliações para utilização do germoplasma coletado.bitstream/CNPAF/26497/1/doc_201.pd

Application of an E. coli biofilm supported on Kaolin to the removal of Cd(II), Cr(VI), Fe(III) and Ni(II) from aqueous solutions

The pollution caused by heavy metals is one the major environmental problems that is imperative to be solved. New technologies, easy to implement and to adapt to any system, deserve special attention and are the focus of this presentation. This paper aims to investigate the biosorption behaviour of a biofilm of E. coli supported on kaolin clay for the treatment of cadmium, iron, nickel and chromium aqueous solutions. The effect of metals initial concentrations were studied and the relationship between pH and removal efficiency were analysed. Adsorption characteristics of a biosorbent can be depicted by an adsorption isotherm. Langmuir, Redlich-Peterson and Sips are commonly used for the description of adsorption data and were applied to the experimental results described by this report. The presence of functional groups in the suspended biomass that may have a role in biosorption process was confirmed by FTIR. It was demonstrated that a biofilm of E. coli supported on kaolin is able to remove Cr (VI), Cd (II), Ni (II) and Fe (III) from aqueous solutions. The isotherms were fitted and the best fit for chromium and nickel was obtained with the Redlich-Peterson model isotherm and for cadmium the best fit was the obtained with the Sips model. In terms of removal percentage, the results showed 100% of removal for iron for the whole range of concentrations tested. For cadmium, the removal percentage remains around 70% for all the initial concentrations tested (between 67.1% and 78.9%) and is higher than the obtained for nickel and chromium. The analyses by FTIR showed that functional groups on the biomass, such as hydroxyl, carboxyl and phosphate groups, may be the main binding sites for biosorption of the studied heavy metals by E. coli. Finally, the metal affinity to the biofilm was found to follow the sequence Fe > Cd > Ni > Cr and the preference of a sorbent for a metal may be explained on the basis of electronegativity of the metal ions and on the basis of the cation/anion state.Fundação para a Ciência e a Tecnologia (FCT)FEDERMinas de Barqueiros, S.A

One-to-one full scale simulations of laser wakefield acceleration using QuickPIC

We use the quasi-static particle-in-cell code QuickPIC to perform full-scale, one-to-one LWFA numerical experiments, with parameters that closely follow current experimental conditions. The propagation of state-of-the-art laser pulses in both preformed and uniform plasma channels is examined. We show that the presence of the channel is important whenever the laser self-modulations do not dominate the propagation. We examine the acceleration of an externally injected electron beam in the wake generated by 10 J laser pulses, showing that by using ten-centimeter-scale plasma channels it is possible to accelerate electrons to more than 4 GeV. A comparison between QuickPIC and 2D OSIRIS is provided. Good qualitative agreement between the two codes is found, but the 2D full PIC simulations fail to predict the correct laser and wakefield amplitudes.Comment: 5 pages, 5 figures, accepted for publication IEEE TPS, Special Issue - Laser & Plasma Accelerators - 8/200

Distribuição ecogeográfica de acessos tradicionais de feijoeiro comum.

O objetivo deste trabalho foi caracterizar a distribuição ecogeográfica em 2903 acessos tradicionais de feijoeiro comum oriundos de coletas realizadas pala Embrapa Arroz e Feijão.bitstream/CNPAF-2009-09/27690/1/comt_153.pd

Core collection brasileira de Phaseolus vulgaris L.

O estabelecimento de uma coleção nuclear contribui significativamente para que um programa de melhoramento tenha acesso a uma grande variabilidade genética para melhor utilização dos recursos genéticos, financeiros e humanos. Diante disso o objetivo do presente trabalho foi avaliar e indicar metodologias e estratégias de amostragem que melhor se adequem ao estabelecimento de uma coleção nuclear.Palestra - CONAFE

Parecença entre acessos tradicionais de feijão carioca utilizando o método de Ward.

O objetivo deste trabalho foi caracterizar a parecença em 126 acessos tradicionais de feijão do grupo comercial carioca, reunindo-os em grupos de similaridade por meio da técnica de agrupamento de Ward aplicada a caracteres morfogeográficos