11,084 research outputs found
Microbial communities shifts in dark fermentative H2 production at mesophilic, thermophylic and hyperthermophylic conditions
Hydrogen is foreseen as a viable CO2-neutral alternative to fossil fuels for generation of energy.
Production of H2 from wastes/wastewaters is possible as this is one of the main products resulting from
anaerobic fermentation of organic compounds. If hydrogenotrophic methanogens are suppressed, H2-rich
biogas can be recovered from anaerobic reactors. In order to optimize and improve H2 production, it is
essential to get more insight into the composition and structure of the microbial communities involved in
the process. In this study microbial community shifts in expanded granular sludge blanket (EGSB)
reactors producing H2 at different temperatures and organic loading rates (OLR) were studied using PCRDGGE
fingerprinting analysis. The aim was to get more insight into the microbiology of dark
fermentative hydrogen production at mesophilic, thermophilic and hyperthermophilic temperatures. Three
EGSB reactors were inoculated with granular biomass previously treated with heat to suppress
methanogens. Reactors were operated at 37, 55 and 70 ºC with 5gCOD L-1of a mixture containing glucose
and L-arabinose (1:1); pH was kept at 5.5. OLR applied varied from 5 to 16. PCR amplification of the
16S rRNA gene and subsequent DGGE analysis of sludge samples collected from the reactors at different
operational times showed different profiling, mainly correlated with differences in temperature. Bacterial
diversity (measured as the number of bands) in sludge samples from reactors operating at 55 ºC and 70ºC
was remarkably lower than in sludges growing at 37ºC. No significant changes on DGGE profiles
diversity were observed with the increase of OLR over time
Bacterial community structure of biohydrogen production process in extreme thermophilic conditions (70ºC)
Resistência de linhagens genitoras e híbridos simples de sorgo a Colletotrichum sublineolum, agente causal da antracnose.
Foi avaliada a reação de resistência de dez híbrido s simples de sorgo (Sorghum bicolor) e 14 linhagens genitoras destes híbridos ao patógeno Colletotrichum sublineolum, agente causal da antracnose. Em casa de vegetação, os genótipos foram inoculados se paradamente com 20 isolados monospóricos obtidos de diferentes regiões produtoras do país. A avaliação foi realizada aos dez dias após a inoculação, utilizando-se escala de notas. Nenhum genótipo de sorgo foi resistente a todos os isolados inoculados. A linhagem CMSXS657 foi resistente a 95%; a linhagem ATF14, a 90%; ATF08, a 85% e CMSXS210, a 70% dos isolados. Dentre os híbridos, destacou-se o BRS305 (CMSX S210A X BR012R), resistente a 75% dos isolados; 9920045 (ATF14A X CMSXS180R), a 65% dos isolados; BRS308 (CMSXS233A X BR012R), a 60% dos isolados e BRS650 (CMSXS222A X CMSXS657R), a 55% dos isolados. As linhagens BR001 e CMSXS222 foram suscetíveis a 90% dos isolados. A frequência de resistência dos híbridos foi igual ou inferior às linhagens genitoras. Exceção faz-se ao híbrido BRS305 (CMSXS2 10A X BR012R), que foi resistente a um maior número de isolados que seus genitores. Nenhum dos isolados testados foi virulento a todos os genótipos. Os isolados de Campo Novo dos Parecis (MT) foram os mais virulentos enquanto os isolados de Jardinópolis (SP) foram os menos virulentos
Microbial community structure of biohydrogen production process in extreme thermophilic conditions
Fundação para a Ciência e a Tecnologia (FCT
New features of the phase transition to superconducting state in thin films
The Halperin-Lubensky-Ma (HLM) effect of a fluctuation-induced change of the
order of phase transition in thin films of type I superconductors with
relatively small Ginzburg-Landau number is considered. Numerical data
for the free energy, the order parameter jump, the latent heat, and the
specific heat of W, Al and In are presented to reveal the influence of film
thickness and material parameters on the properties of the phase transition. We
demonstrate for the first time that in contrast to the usual notion the HLM
effect occurs in the most distinct way in superconducting films with high
critical magnetic field rather than in materials with small .
The possibility for an experimental observation of the fluctuation change of
the order of superconducting phase transition in superconducting films is
discussed.Comment: 11 pages, MikTexTeX, 3 fig, 2 Tables, corrected some typos, Submitted
J.Phys:Cond Ma
Extreme thermophilic biohydrogen production from arabinose and glucose
Continuous hydrogen production rate from arabinose was significantly higher than from glucose,
when higher organic loading rate was used. This fact was associated to higher lactate production in
the reactor fed with glucose. The higher concentration of lactate was not a consequence of bacterial
community shift, and is likely related to changes in the main metabolic pathways of glucose
catabolism
Teste de condutividade elétrica em sementes de jequitibá-rosa (Cariniana legalis) O. Kuntze.
Resumo
Teste bioquímico em embriões de pinheiro-brasileiro (Araucaria angustifolia) Bert. O. Kuntze.
Resumo
Cortina amarela e azul, programas de luz quase contínuo e intermitente, na produção de frangos de corte.
Projeto/Plano de Ação: 06.06.02.359-02
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