Saturação em CO2 e regulação metabólica do bacterioplancton em ecossistemas aquáticos de baixa latitude

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Short-term temporal changes of soil carbon losses after tillage described by a first-order decay model

Tillage stimulates soil carbon (C) losses by increasing aeration, changing temperature and moisture conditions, and thus favoring microbial decomposition. In addition, soil aggregate disruption by tillage exposes once protected organic matter to decomposition. We propose a model to explain carbon dioxide (CO2) emission after tillage as a function of the no-till emission plus a correction due to the tillage disturbance. The model assumes that C in the readily decomposable organic matter follows a first-order reaction kinetics equation as: dC(sail)(t)/dt = -kC(soil)(t) and that soil C-CO2 emission is proportional to the C decay rate in soil, where C-soil(t) is the available labile soil C (g m(-2)) at any time (t). Emissions are modeled in terms soil C available to decomposition in the tilled and non-tilled plots, and a relationship is derived between no-till (F-NT) and tilled (F-Gamma) fluxes, which is: F-T = a1F(NT)e(-a2t), where t is time after tillage. Predicted and observed fluxes showed good agreement based on determination coefficient (R-2), index of agreement and model efficiency, with R-2 as high as 0.97. The two parameters included in the model are related to the difference between the decay constant (k factor) of tilled and no-till plots (a(2)) and also to the amount of labile carbon added to the readily decomposable soil organic matter due to tillage (a,). These two parameters were estimated in the model ranging from 1.27 and 2.60 (a(1)) and - 1.52 x 10(-2) and 2.2 x 10(-2) day(-1) (a(2)). The advantage is that temporal variability of tillage-induced emissions can be described by only one analytical function that includes the no-till emission plus an exponential term modulated by tillage and environmentally dependent parameters. (C) 2008 Elsevier B.V. All rights reserved.

Short-term temporal changes of bare soil CO2 fluxes after tillage described by first-order decay models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of insulin-like growth factor-1 during in vitro oocyte maturation and in vitro culture of bovine embryos

Avaliaram-se o efeito do IGF-I na maturação in vitro (MIV) (experimento I) e no desenvolvimento embrionário (DE) (experimento II) de oócitos bovinos fecundados in vitro, quanto às taxas de clivagem (TC), de blastocistos (TB) e de eclosão (TE). Para MIV, complexos cumulus-oócitos imaturos foram cultivados em meio TCM-199 suplementado com HEPES, bicarbonato e piruvato de sódio, aditivos, soro fetal bovino (meio B-199) e gonadotrofinas 14U/ml de PMSG e 7U/ml de hCG). Para o desenvolvimento embrionário, os oócitos/zigotos foram cultivados em meio B-199 com células epiteliais do oviduto bovino em suspensão sob óleo de silicone. As condições de cultivo in vitro para ambos os experimentos seguiram os tratamentos: 1- meio B-199 + 200 ng/ml IGF-I; 2- B-199 + 100 ng/ml IGF-I; 3- B-199 + 50 ng/ml IGF-I; 4- B-199 + 10 ng/ml IGF-I; 5- B-199 + 0 ng/ml IGF-I. Todas as culturas foram realizadas a 38,5° C em atmosfera com 5% de CO2 e os dados foram analisados pelo teste do qui-quadrado. No experimento I, não houve diferença (P>0,05) entre os tratamentos quanto às TC, TB e TE, quando o meio de MIV foi suplementado com IGF-I. No experimento II, a adição de IGF-I ao meio de DE resultou em aumento na TC (P<0,05) mas não influenciou a TB e a TE. A adição de 200 ng/ml de IGF-I ao meio DE melhorou a TC (71,1%) quando comparada com a TC dos grupos de 100 ng/ml de IGF-I (57,6%) ou controle (56,7%), entretanto não houve diferença quando comparada com a dos grupos de 50 ng/ml (69,4%) ou 10 ng/ml (73,1%) de IGF-I. Não houve efeito benéfico na adição de 10 a 200 ng/ml de IGF-I nos meios de MIV e de DE com relação ao desenvolvimento de embriões produzidos a partir de oócitos maturados e fecundados in vitro.

Locus coeruleus is a central chemoreceptive site in toads

The locus coeruleus (LC) has been suggested as a CO2 chemoreceptor site in mammals. This nucleus is a mesencephalic structure of the amphibian brain and is probably homologous to the LC in mammals. There are no data available for the role of LC in the central chemoreception of amphibians. Thus the present study was designed to investigate whether LC of toads (Bufo schneideri) is a CO2/H+ chemoreceptor site. Fos immunoreactivity was used to verify whether the nucleus is activated by hypercarbia (5% CO2 in air). In addition, we assessed the role of noradrenergic LC neurons on respiratory and cardiovascular responses to hypercarbia by using 6-hydroxydopamine lesion. To further explore the role of LC in central chemosensitivity, we examined the effects of microinjection of solutions with different pH values (7.2, 7.4, 7.6, 7.8, and 8.0) into the nucleus. Our main findings were that 1) a marked increase in c-fos-positive cells in the LC was induced after 3 h of breathing a hypercarbic gas mixture; 2) chemical lesions in the LC attenuated the increase of the ventilatory response to hypercarbia but did not affect ventilation under resting conditions; and 3) microinjection with acid solutions (pH = 7.2, 7.4, and 7.6) into the LC elicited an increased ventilation, indicating that the LC of toads participates in the central chemoreception.

Enhanced solubilization of iron and calcium phosphates by Aspergillus niger by the addition of alcohols

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Soil CO2 emission of sugarcane fields as affected by topography

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lactate sequestration by osteoderms of the broad-nose caiman, Caiman latirostris, following capture and forced submergence

Lactate accumulation in osteoderms; of the broad-nose caiman, Caiman latirostris, was determined following capture and surgery and after a period of forced submergence and related to concurrent values in blood. Control samples of bone and blood were taken after recovery from surgery and before submergence. In addition, samples of osteoderm were incubated in a lactate solution to determine equilibrium concentration, and additional samples were analyzed for elemental and CO2 concentrations. The composition of the osteoderms closely resembles that of typical vertebrate bone, with a high concentration of calcium and phosphate. Plasma and osteoderm lactate concentrations were both elevated following surgery and decreased significantly after 1 day of recovery. Submergence produced a typical lactate pattern in the plasma, with only a modest increase during the dive and then a sharp increase during recovery to a peak of 31.2 +/- 1.9 mumol ml(-1) after 1 h. When caimans were anesthetized 2 h after submergence, osteoderm lactate in the same animals was significantly increased to 14.8 mumol g(-1) wet mass. The ratio of the osteoderm: plasma lactate concentration after submergence was similar to the ratio observed in the incubated samples, suggesting that osteoderm lactate concentrations in vivo were equilibrated with circulating plasma levels. We conclude that caiman osteoderms sequester lactate during lactic acidosis and that the time course is fast enough to have benefit to these animals following normal anaerobic burst activity.

Corn and soybean meal metabolizable energy with the addition of exogenous enzymes for poultry

Two metabolism assays were carried out to determine corn and soybean meal metabolizable energy when enzymes were added. In the first trial, 35 cockerels per studied feedstuff (corn and soybean meal) were distributed in a completely randomized experimental design with four treatments of seven replicates of one bird each. The evaluated treatments were: ingredient (corn and soybean meal) with no enzyme addition, with the addition of an enzyme complex (xylanase, amylase, protease - XAP), xylanase, or phytase. Precise feeding method was used to determine true metabolizable energy corrected for nitrogen balance (TMEn). The use of enzymes did not result in any differences (p>0.05) in soybean meal TMEn, but phytase improved corn TMEn in 2.3% (p=0.004). In the second trial, 280 seven-day-old broiler chicks were distributed in a completely randomized experimental design with seven treatments of five replicates of eight birds each. Treatments consisted of corn with no enzyme addition or with the addition of amylase, xylanase, phytase, XAP complex, XAP+phytase combination, or xylanase/ pectinase/β-glucanase complex (XPBG). Corn was supplemented with macro and trace minerals. Total excreta collection was used to determine apparent metabolizable energy corrected for nitrogen balance (AMEn). Differences were observed (p=0.08) in AMEn and dry matter metabolizability coefficient (p=0.03). The combination of the XAP complex with phytase promoted a 2.11% increase in corn AMEn values, and the remaining enzymes allowed increased between 0.86% and 1.66%.

Adição de geomanta e tecido não tecido de polipropileno em cimentos geopoliméricos de pega rápida

Geopolymers are cementing materials that depict a number of advantages compared to Portland cement. Contrary to the latter, geopolymers are synthesized at room temperature, thus significantly reducing the emission of CO2 to the atmosphere. Moreover, the composition and synthesis reactions can be tailored to adjust the setting time of the material as well as its compressive mechanical strength. It is then possible to produce geopolymeric cements with short setting times and high compressive strength, although relatively brittle. The objective of the present study was to produce and characterize composite materials by reinforcing fastsetting geopolymeric matrixes with polypropylene geosynthetics (geomats and geotextiles) in an attempt to improve the toughness and tensile strength of the cementing material. Geosynthetics have been increasingly used to reinforce engineering structures, providing higher strength and better toughness. In particular, polypropylene nonwoven and geomats depict other attractive properties such as low density, durability, impact absorption and resistance to abrasion. Fast-setting geopolymers were then synthesized and reinforced with polypropylene nonwoven and geomats. The mechanical strength of the materials, reinforced or not, was characterized. The results showed that relatively short setting times and adequate flowing behavior were achieved by adjusting the composition of the geopolymer. In addition, it is possible to improve the fracture resistance of geopolymeric cements by adding polypropylene geosynthetics. The best results were achieved by reinforcing geopolymer with polypropylene TNT

Deposição de calda de pulverização sobre plantas de salvínia em função de pontas de pulverização e arranjos populacionais entre plantas de Aguapé e Alface-D'Água

Este trabalho teve como objetivo avaliar o depósito de calda pulverizada por dois tipos de pontas de pulverização sobre plantas de Salvinia auriculata dispostas em diferentes arranjos populacionais com plantas de Eichhornia crassipes e Pistia stratiotes. Um experimento foi conduzido em condições de caixas-d'água em delineamento inteiramente casualizado, com quatro repetições. Os tratamentos foram dispostos em esquema fatorial 2 x 8, sendo dois tipos de pontas de pulverização (ConeJet TXVK-8 e TeeJet DG 11002 VS) e oito proporções entre as plantas aquáticas, a saber: dominância total da área de cobertura da caixa-d'água pelas plantas de salvínia (100%); e as proporções entre plantas de salvínia e de aguapé ou alface-d'água a 75%:25%, 50%:50% e 25%:75%. Também foi utilizada uma densidade tripla, na qual as três espécies estiveram igualmente dispostas na proporção de 33%. Soluções dos corantes Amarelo Tartrasina FDC-5 a 3.500 ppm e Azul Brilhante FDC-1 a 1.000 ppm foram utilizadas como traçadores para as pontas TXVK-8 e DG 11002VS, respectivamente. A pulverização das soluções foi efetuada na mesma unidade experimental, com intervalo de 30 minutos entre si, com auxílio de um pulverizador costal pressurizado com CO2, calibrado de modo que proporcionasse volume de aplicação aproximado de 200 L ha-1. Não foram observadas diferenças estatísticas entre os tipos de pontas de pulverização nas diferentes proporções estudadas, exceto para depósitos totais de calda de pulverização nas plantas na condição de dominância total da salvínia, uma vez que a ponta ConeJet TXVK-8 foi superior à TeeJet DG 11002 VS. Os valores dos depósitos diminuíram com o aumento da proporção de plantas de aguapé na associação e foram na condição em que 25% de plantas de salvínia estiveram associadas a 75% de plantas de aguapé. A presença da espécie alface-d'água não influenciou a deposição de gotas sobre as folhas de salvínia.

Desgaste corrosivo-cavitativo-erosivo de um aço-carbono em meio aquoso com frações de sal (NaCl), CO2 e particulados sólidos (SiO2)

A batch of eighty-four coupons of low carbon steel were investigated at laboratory conditions under a corrosive, cavitative-corrosive (CO2) and corrosive-erosive (SiO2 + CO2) in an aqueous salt solution and two levels of temperature. The following measurements were made on Vickers (HV0,05, HV0,10, HV0,20) Microhardness tests at three levels of subsurface layer. A turbulent flow collided on the cylindrical sample, with and without mechanical stirring and gas bubbling, with and without fluid contamination by solid particles of SiO2, at two temperatures. Surface Roughness and Waviness, under two conditions "as received, after machining" and "after worn out", as well as gravimetric and electrochemical parameter were measured on the two opposite generatrices of each cylindrical sample, on the flow upstream (0°) and downstream (180°) by Profilometry, Mass Variation and Linear Polarization Resistance (LPR). The results of the Microhardness and Surface Texture of all coupons were subjected to statistical comparison, using the software Statgraphics® Centurion XVI, 95% statistical certainty, and significant differences were observed in some arrays of measurements. The corrosive wear rate measured by LPR and mass variation shown to be sensitive to the presence of bubbles and hydrodynamic fluctuations inside the cell, considering the temperature and contamination of corrosive fluid by solid particles. The main results of visual inspection relative to some topologies of the surface damages involving different mechanisms that were seen to give explanation for some fluctuations in wear rates of the steel experimentally investigated

Influência da formação de pozolanas com adição de metacaulim em concreto de alta resistência

The need to build durable structures and resistant to harsh environments enabled the development of high strength concrete, these activities generate a high cement consumption, which implies factor in CO2 emissions. Often the desired strength is not achieved using only the cement composition. This study aims to evaluate the influence of pozzolans with the addition of metakaolin on the physical mechanics of high strength concrete comparing them with the standard formulation. Assays were performed to characterize the aggregates according to NBR 7211, evaluation of cement and coarse aggregate through the trials of petrography (NBR 15577-3/08) and alkali-aggregate reaction (NBR 15577-05/08). Specimens were fabricated according to NBR 5738-1/04 with additions of 0%, 4%, 6%, 8% and 10% of metakaolin for cement mortars CP V in the formulations. For evaluation of the concrete hardened in fresh state and scattering assays were performed and compressive strength in accordance with the NBR 7223/1992 and NBR 5739-8/94 respectively. The results of the characterization of aggregates showed good characteristics regarding size analysis and petrography, as well as potentially innocuous as the alkali-aggregate reaction. As to the test of resistance to compression, all the formulations with the addition of metakaolin showed higher value at 28 days of disruption compared with the standard formulation. These results present an alternative to reduce CO2 emissions, and improvements in the quality and durability of concrete, because the fine particle size of metakaolin provides an optimal compression of the mass directly influencing the strength and rheology of the dough

Avaliação da decomposição de plantas aquáticas no solo através da liberação de CO2

O objetivo deste trabalho foi avaliar a decomposição de três espécies de plantas aquáticas imersas, incorporadas ao solo, provenientes do controle mecânico, em reservatórios de usinas hidrelétricas. O estudo foi realizado em casa de vegetação, localizada no Núcleo de Pesquisas Avançadas em Matologia (NUPAM) da FCA/Unesp-Botucatu. A avaliação foi conduzida em vasos contendo 14 kg de solo, com três incorporações de 50 e 100 t MF de plantas ha-1, sob duas condições de solo: seco e úmido. Com a simulação de descarte da biomassa coletada e incorporada ao solo, pôde-se conhecer, através da liberação de CO2, a degradação de três espécies de macrófitas aquáticas submersas. Para quantificação do CO2 liberado, em cada vaso foi acondicionado um frasco com solução de NaOH, sendo, logo após, lacrados e incubados por 24 horas; em seguida, foram titulados com HCl. Para ajuste e interpolação dos dados, estes foram analisados seguindo modelo de Mitscherlich, com algumas modificações. As liberações acumuladas em solo úmido foram de 1.294 e 1.582 kg CO2 ha-1, sendo 6,2 e 5,6 vezes superiores ao ocorrido em solo seco, para 50 e 100 t MF ha-1, respectivamente, observando-se que cerca de 55% da liberação de CO2 ocorreu nos primeiros 30 dias. Pode-se concluir que o solo seco é a melhor condição para descarte e incorporação da biomassa, porém deverá existir um sistema de irrigação para que o processo de degradação da biomassa incorporada seja acelerado.