990 resultados para degradation processes
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Thermal behavior of pyrazolyl complexes [PdCl2(HPz)2] (1), [PdCl2(HdmPz)2] (2), [Pd(SCN)2(HPz) 2] (3), [Pd(SCN)2(HdmPz)2] (4), [Pd(N 3)2(HdmPz)2] (5), [Pd(PzNHCO)2] (6) and [Pd(dmPzNHCO)2] (7) (HPz=pyrazole, HdmPz=3,5-dimethylpyrazole) has been studied by TG and DTA. In general, the thermal stability of [PdX 2(HL)2] (HL=HPz, HdmPz) compounds varies in the following order: HdmPz>HPz as well, according to the trends X=Cl ->SOT->NNN-. Except for 5, the [PdX 2(HL)2] complexes showed higher thermal stability than the 6 and 7 chelates. No stable intermediates were isolated during the thermal decompositions because of the overlapping degradation processes. The final products of the thermal decompositions were identified as metallic palladium by X-ray powder diffraction. © 2005 Akadémiai Kiadó, Budapest.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Engenharia Civil - FEIS
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Engenharia Civil - FEIS
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Since the Seventies, there has been a growing degradation of concrete structures in Brazil. For that reason, much research has been made on the durability of those structures, aiming at contributing towards quality improvement and reduction of maintenance and repair costs. This study evaluates the behavior of the durability of high-performance concrete with additions, replacing part of the cement and aggregates with rice husk ash and tire rubber, respectively. Durability tests were carried out in which concrete was subjected to several degradation processes, such as the action of water, temperature, salts and acid solution. The results indicated that the addition of active silica or rice husk ash, both with tire rubber did not worsen the durability of concrete. In fact, rubber proved to be very effective in preventing the action of chemical agents, high temperatures and the penetration of water. Rice husk ash, despite the larger diameter of particles, had similar results to that of the active silica.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The present study was concerned with checking the water quality, the recovery of the riparian vegetation and vegetation around the springhead of stream Bandeirantes, such as the inadequate disposal of waste along this stream, which is located in Rio Claro, SP, in the period from March to July of 2010. Aiming to propose mitigation measures to reverse the degradation processes and develop activities to help a better awareness of the population directly related to this water resource. The water quality was analyzed by performing monthly sampling in three different points along the stream. The first point of sampling is in the spring of the stream, the second at the region called estradão and the third near its mouth, when it flows into the Ribeirão Claro, a tributary of the right bank of the Corumbataí river. It was calculated from the Water Quality Index (WQI) developed by Cetesb. The results were compared with current law. The riparian vegetation, which is responsible for the protection of rivers and streams, was observed and examined during the field work. The results indicated the stream as class 2 and the WQI has been classified, in the most of the analysis, such as a water of good quality. However, some parameters showed a worrying situation and highlighted the current situation, with waste deposits, furniture and animal waste into the pit of the stream studied
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Compounds released into the environment can induce genetic alterations in living organisms. A group of chemicals that shows proven toxicity is the pesticides, and the insecticides are the most harmful. The insecticides of the family phenylpyrazole have wide application both in agriculture and in homes. Fipronil, an insecticide of this chemical group, is widely used in various cultures and in homes, mainly for fighting fleas and ticks on dogs and cats. The use of fipronil may represent a risk to man and the environmental health, since this pesticide can potentially induce cell death, regardless of cell type. Fipronil, when in contact with the environment, can undergo various degradation processes, including photodegradation. The toxic effect of one of its metabolites derived from photodegradation, sulfone-fipronil, is approximately 20 fold as great as fipronil itself. The A. cepa test system was used to evaluate cytotoxic, genotoxicity and mutagenic effects of fipronil before and after phptodegradation. Seeds of Allium cepa were subjected to solutions of fipronil, pre-exposed or not exposed to degradation by sunlight. The germination tests were conducted both under the effect of light and in the dark. We evaluated the cumulative potential of this insecticide using 48 and 72-hours recovery tests. The results showed that when fipronil was previously exposed to the sun, it presented a greater genotoxic and mutagenic potential, showing that the metabolites formed by photodegradation can show more harmfull effects
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Glycogen functions as a carbohydrate reserve in a variety of organisms and its metabolism is highly regulated. The activities of glycogen synthase and glycogen phosphorylase, the rate-limiting enzymes of the synthesis and degradation processes, respectively, are regulated by allosteric modulation and reversible phosphorylation. To identify the protein kinases affecting glycogen metabolism in Neurospora crassa, we performed a screen of 84 serine/threonine kinase knockout strains. We identified multiple kinases that have already been described as controlling glycogen metabolism in different organisms, such as NcSNF1, NcPHO85, NcGSK3, NcPKA, PSK2 homologue and NcATG1. In addition, many hypothetical kinases have been implicated in the control of glycogen metabolism. Two kinases, NcIME-2 and NcNIMA, already functionally characterized but with no functions related to glycogen metabolism regulation, were also identified. Among the kinases identified, it is important to mention the role of NcSNF1. We showed in the present study that this kinase was implicated in glycogen synthase phosphorylation, as demonstrated by the higher levels of glycogen accumulated during growth, along with a higher glycogen synthase (GSN) ±glucose 6-phosphate activity ratio and a lesser set of phosphorylated GSN isoforms in strain Ncsnf1KO, when compared with the wild-type strain. The results led us to conclude that, in N. crassa, this kinase promotes phosphorylation of glycogen synthase either directly or indirectly, which is the opposite of what is described for Saccharomyces cerevisiae. The kinases also play a role in gene expression regulation, in that gdn, the gene encoding the debranching enzyme, was down-regulated by the proteins identified in the screen. Some kinases affected growth and development, suggesting a connection linking glycogen metabolism with cell growth and development.
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Pós-graduação em Agronomia (Ciência do Solo) - FCAV