971 resultados para mistura polimérica
Resumo:
The use of pesticides in Brazil has intensified over the years. And since 2009 it was ranked as the largest market for pesticides worldwide. The consequential diffuse contamination of the environment is therefore due to the increasing number of chemicals of different classes, origins and modes of action. Little is known about the action of pesticides on human health in situations of co-exposure. Possible toxic effects are not restricted to agricultural and industrial workers, but also the general population that may be exposed continuously to its residues in food and water. Although these pesticides are mostly present in the environment at low doses, it must be considered that possible cumulative or synergistic effects may occur when there are concurrent or sustained exposure for two or more of these agents, which can lead to late manifestation of subclinical damages, sometimes irreversible. Thus, the specific objective of this study was to assess the effect of carcinogenesis promotion of a mixture of pesticides at low doses and analyze the phenomena of cell proliferation and apoptosis in rat liver. A total of 50 male Lewis rats was separated into 5 groups for 8 weeks in a medium term hepatocarcinogenesis model. The three different classes of pesticides (dieldrin, dicofol, endosulfan, dichlorvos and permethrin), whose residues were detected by ANVISA during the period from 2001 to 2005 in tomatoes cultures, were added to the feed of rats initiated to hepatocarcinogenesis with diethylnitrosamine (DEN- 200mg/kg ip). We used two different mixtures, one with no toxic effects at doses (MEX1) referring to the NOEL (no-observed-effect level) and another at doses LOEL / LEL / LOAEL (Lowest-observed-effect level / Lowest-effect level / Lowest -observed-adverse-effect level), to the installation of adverse effects (MEX2), derived from chronic studies. All animals ...(Complete abstract click electronic access below)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Pós-graduação em Engenharia Mecânica - FEG
Resumo:
Pós-graduação em Engenharia Mecânica - FEG
Resumo:
Pós-graduação em Engenharia Civil - FEIS
Resumo:
Pós-graduação em Biofísica Molecular - IBILCE
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Despite the great development of organic and polymeric electroluminescent materials, the large scale commercial application of devices made with these materials seems conditioned to specific cases, mainly due to the high cost and the low durability, in compared to conventional technologies. In this study was produced electroluminescent devices by a process simple, drop casting. Were produced electroluminescent films containing Zn2SiO4:Mn immersed in a conductive polymer blend with different thicknesses. The morphological characteristics of these films were studied by scanning electronic microscopy. These films were used in the manufacture of electroluminescent devices, in which the light emission properties of the developed material were evaluated. The blend was composed of the conductive polymer Poly(o-methoxyaniline), doped with p-toluene sulfonic acid, and an insulating polymer, Poly(vinylidene fluoride) and its copolymer Poly(vinylidene fluoride-cotrifluoroethylene). To this blend was added Zn2SiO4:Mn, thereby forming the composite. A first set of devices was obtained using composites with different weight fraction of polymeric and inorganic phases, which were deposited by drop casting over ITO substrates. Upper electrodes of aluminum were deposited by thermal evaporation. The resulting device architecture was a sandwich type structure ITO/ composite/ Al. A second set of devices was obtained as self-sustaining films using the best composite composition obtained for the device of the first set. ITO electrodes were deposited by RF-Sputtering, in both faces of these films. The AC electrical characterization of the devices was made with impedance spectroscopy measurements, and the DC electrical characterization was performed using a source/ meter unit Keithley 2410. The devices light emission was measured using a photodiode coupled to a digital electrometer, Keithley 6517A. The devices electrooptical characterization showed that the...
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
Pós-graduação em Agronomia (Produção Vegetal) - FCAV
Resumo:
Pós-graduação em Física - IFT