Soil CO2 emission as related to incorporation of sugarcane crop residues and aggregate breaking after rotary tiller

O preparo do solo é um dos processos que aceleram a decomposição da matéria orgânica, transferindo carbono para atmosfera, principalmente na forma de CO2. Neste trabalho, investigou-se o efeito do preparo com enxada rotativa sobre as emissões de CO2 do solo durante 02 semanas após o preparo do solo, incluindo-se a presença de resíduos vegetais sobre a superfície. As emissões foram avaliadas por 15 dias após preparo em 3 parcelas: 1) sem preparo e sem palha superficial (SPs); 2) preparo com enxada rotativa sem a presença de palha na superfície (ERs), e 3) preparo com enxada rotativa com a presença de palha superficial (ERc). As emissões provenientes da ERc foram superiores às demais (0,777 g CO2 m-2 h-1), sendo as menores emissões registradas na parcela SPs (0,414 g CO2 m-2 h-1). As emissões totais indicaram que a diferença de C-CO2 emitida à atmosfera corresponde a 3% do total de carbono adicional presente na palha, na parcela ERc, quando comparado à parcela ERs. O aumento da emissão da parcela SPs para ERs foi acompanhado de uma modificação na distribuição do tamanho de agregados, especialmente aqueles com diâmetro médio inferior a 2 mm. O aumento da emissão da parcela ERs para ERc esteve relacionado a uma diminuição da massa de palha na superfície, com fragmentação e incorporação da mesma no interior do solo. Quando se analisa a correlação linear entre emissão de CO2 versus temperatura e umidade do solo, somente a emissão da ERc foi significativamente correlacionada (p<0,05) à umidade do solo.

Log smoldering after an Amazonian deforestation fire

The characteristics of log smoldering after an Amazonian deforestation fire are described. The experiment was carried out in 2001 at the Caiabi farm, near the city of Alta Floresta, state of Mato Grosso, Brazil, as part of a set of tests that have been performed in the same area since 1997. A 200 x 200m(2) test area was slashed in the beginning of June and burned on 20 August. The area contained 507 logs with diameter at breast height (DBH) higher than 10 cm, per hectare. In the day following the main burn 59 logs were found to remain smoldering, a number that corresponds to 2.9% of the total in the area. We chose 11 of the 59 logs to have their smoldering process monitored. Their diameter, moisture content and CHN dry biomass composition after the plot burn and before smoldering were determined. Other parameters such as temperature distribution while smoldering, porosity, density and mass volatilized during thermogravimetric test were also determined. Average smoldering speeds were in the range from 0.8 to 1.5 cm h(-1) for logs that smoldered without transition to the flaming regime. The average speed increased to 2.1 cm h(-1) for those logs that oscillated between smoldering and flaming. The speeds were lower overnight as compared to values determined during daytime for the same log. Higher log moisture contents were found to produce decreased speeds. Micro-porous biomass was not observed in the set of the 11 selected logs. Smoldering was observed to occur at substantial intensity in crossing of logs, with no longitudinal propagation. (C) 2003 Elsevier Ltd. All rights reserved.

O poder e as injustiças nas pesquisas em seres humanos

Após considerações gerais sobre a ética na pesquisa envolvendo seres humanos, focaliza-se a possibilidade de ocorrências de injustiças, sob a égide de diversas formas de poder. Exemplificam-se situações concretas. Enfatiza-se a análise das possíveis injustiças à luz da Bioética, com destaque para multi e transdisciplinaridade. O autor se posiciona quanto às características atuais da Bioética, cuja ótica levou à elaboração das Diretrizes éticas para a pesquisa envolvendo seres humanos, no Brasil (Resolução 196/96 e complementares do Conselho Nacional de Saúde). Descreve-se a sistemática das atividades do Grupo Executivo de Trabalho - GET, designado pelo Conselho Nacional de Saúde (órgão de controle social na área da saúde), para elaborar as Diretrizes. É dado destaque à participação dos diversos segmentos da sociedade, evidenciando multi e transdiciplinaridade, sob a coordenação do GET, do qual o autor foi Presidente. Comentam-se os principais tópicos das Diretrizes brasileiras, enfocando-se a sua relação com o tema de poder e injustiça. Salienta-se o papel dos Comitês de Ética em Pesquisa - CEP e da Comissão Nacional de Ética em Pesquisa - CONEP.

Electrochemical reduction and determination of Cibacron Blue F3GA at poly-L-lysine modified glassy carbon electrode

The oxidation of a reactive dye, Cibacron Blue F3GA, CB, (C.I. 61211), widely used in the textile industries to color natural fibers, was studied by electrochemical techniques. The oxidation on glassy carbon electrode occurs in two steps at 2.0 < pH < 10 involving one electron transfer each to the amine group leading to the imide derivative. Stable films of poly-L-lysine (PLL) in the presence of glutaraldehyde (GA) 97.5%:2.5% on glassy carbon electrode can be used to detect low levels of dye using its oxidation peak at +0.75V by voltammetry. Linear calibration graphs were obtained for the CB reactive dye, from 1.0 X 10(-6) to 1.0 X 10(-5) mol L-1 in B-R buffer, pH 2.0, using a pre-concentration off-line during 10 min. The detection limit (3 sigma/slope) was calculated to be 4.5 X 10(-8) mol L-1. Films of PLL can readily be applied for the determination of CB dye bearing aminoanthraquinone as chromophore and chlorotriazinyl as reactive group at concentrations at least 100 times lesser than using a glassy carbon electrode without modification. The method described was applied for the determination of CB dye in tap water and raw water collected from the municipal treatment plant with a recovery of 89.2% +/- 5.4 and 88.0% +/- 6.5, respectively. (c) 2005 Elsevier Ltd. All rights reserved.

Anaerobic digestion of stillage to produce bioenergy in the sugarcane-to-ethanol industry

Stillage is the main wastewater from ethanol production, containing a high chemical oxygen demand in addition to acidic and corrosive characteristics. Though stillage may be used as a soil fertilizer, its land application may be considered problematic due its high polluting potential. Anaerobic digestion represents an effective alternative treatment to reduce the pollution load of stillage. In addition, the methane gas produced within the process may be converted to energy, which can be directly applied to the treatment plant. The objective of this paper was to investigate the energetic potential of anaerobic digestion applied to stillage in the sugarcane ethanol industry. An overall analysis of the results indicates energy recovery capacity (ERC) values for methane ranging from 3.5% to 10%, respectively, for sugarcane juice and molasses. The processes employed to obtain the fermentable broth, as well as the distillation step, represent the main limiting factors to the energetic potential feasibility. Considering financial aspects the annual savings could reach up to US$ 30 million due to anaerobic digestion of stillage in relatively large-scale distilleries (365,000 m3 of ethanol per year). The best scenarios were verified for the association between anaerobic digestion of stillage and combustion of bagasse. In this case, the fossil fuels consumption in distilleries could be fully ceased, such the ERC of methane could reach values ranging from 140% to 890%. © 2013 Taylor & Francis.

Influência do local de seguimento da mola hidatiforme no prognóstico e tratamento da neoplasia trofoblástica gestacional pós-molar

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A transição de contextos: inter relação entre instituição de educação infantil e família de criança de três anos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)