1000 resultados para Toxic emissions


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BACKGROUND. The present report was carried out to determine whether alcohol intake could induce prostate lesions.METHODS. We tested male rats for 300 days. Animals were divided into three groups: controls received only tap water as liquid diet; the chronic alcohol intake group received only ethanol solution in semivoluntary research; and the withdrawal group received the same treatment as chronic alcohol intake until 240 days, after which they reverted to drinking water.RESULTS. Chronic alcohol intake increased lipoperoxide concentrations and acid phosphatase activities. Cu-Zn superoxide dismutase (SOD) was decreased at 60 days, but approached controls values at 300 days following treatment. The serum increased alkaline phosphatase, and alanine transaminase activities reflected the chronic toxic effect of ethanol.CONCLUSIONS. Since SOD activity was unable to scavenge superoxide radical and lipoperoxide formation, we can conclude that superoxide is an important intermediate in prostate damage of chronic alcohol intake. (C) 1997 Wiley-Liss, Inc.

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Determining the variability of carbon dioxide emission from soils is an important task as soils are among the largest sources of carbon in biosphere. In this work the temporal variability of bare soil CO2 emissions was measured over a 3-week period. Temporal changes in soil CO2 emission were modelled in terms of the changes that occurred in solar radiation (SR), air temperature (T-air), air humidity (AR), evaporation (EVAP) and atmospheric pressure (ATM) registered during the time period that the experiment was conducted. The multiple regression analysis (backward elimination procedure) includes almost all the meteorological variables and their interactions into the final model (R-2 = 0.98), but solar radiation showed to be the one of the most relevant variables. The present study indicates that meteorological data could be taken into account as the main forces driving the temporal variability of carbon dioxide emission from bare soils, where microbial activity is the sole source of carbon dioxide emitted. (C) 2003 Elsevier B.V. All rights reserved.

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A combined experimental and theoretical study was conducted to analyze the photoluminescence (PL) properties of ordered and disordered CaWO4 (CW) and CaMoO4 (CM) powders. Two mechanisms were found to be responsible for photoluminescence emission in CW and CM powders. The first one, in the disordered powders, was caused by oxygen complex vacancies [MO3 center dot V-O(x)], [MO3 center dot V-O(center dot)] and [MO3 center dot V-O(center dot center dot)], where M=W or Mo, which leads to additional levels in the band gap. The second mechanism, in ordered powders, was caused by an intrinsic slight distortion of the [WO4] or [MoO4] tetrahedral in the short range. (c) 2007 American Institute of Physics.

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Toxic megacolon occurs in colitis of differing aetiology. This report describes 15 patients with chagasic megacolon with this complication. The clinical signs and symptoms in all patients were pain and progressive abdominal distension accompanied by fever, severe toxaemia and shock. Seven patients developed this clinical pattern after manual removal of faeces. The remaining patients had pain and abdominal distension followed by signs of severe toxaemia when first examined. Nine patients underwent total colectomy with ileostomy (one death), four partial colectomy (all died) and two received medical treatment (both died). At autopsy, three of the four patients undergoing partial colectomy had residual colitis and enteritis. The surgical procedure of choice for this complication of chagasic megacolon is total colectomy.

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Pollution, industrial solvents, concentrations of metals and other environmental agents are widely related to biochemicals values which are used in disease diagnosis of environmental toxicity. A rat bioassay validated for the identification of toxic effects of eutrophication revealed increased serum activities of amylase, alanine transaminase (BLT) and alkaline phosphatase (ALP) in rats that received algae, filtered water and nickel or cadmium from drinking water. Serum Cu-Zn superoxide dismutase activity decreased from its basal level of 40.8 +/- 2.3 to 26.4 U/mg protein, at 7 days of algae and at 48 hr of nickel and cadmium water ingestion. The observation that lipoperoxide concentration was not altered in rats treated with filtered water, while amylase, ALT and ALP were increased in these rats and in those treated with nickel or cadmium, indicated that pancreatic, hepatic and osteogenic lesions by eutrophication were not related to superoxide radicals, and might be due to a novel toxic environmental agent found in filtered and non-filtered algae water.

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In this work, Eu(III) and Eu(II) doped gadolinium silicates has been obtained as compact tubes starting from spherical gadolinium hydroxide carbonate using the pores of silica matrix as support and its surface as reagent. Eu(III) doped gadolinium silicate with hexagonal phase shows an interesting visible shifted charge transfer band when compared to disilicate with orthorhombic phase that was also obtained. Eu(II) gadolinium silicate has been prepared using CO atmosphere presenting an intense blue emission. The divalent europium system shows a potential application as an UV-blue converter. The samples were characterized by scanning electron microscopy (SEM), X-ray powder diffractometry (XRD) and photoluminescence spectroscopy. (C) 2002 Elsevier B.V. B.V. All rights reserved.

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We report here on the application of a compact ultraviolet spectrometer to measurement of NO2 emissions from sugar cane field burns in São Paulo, Brazil, the time-resolved NO2 emission from a 10 ha plot peaked at about 240 g (NO2) s(-1), and amounted to a total yield of approximately 50 kg of N, or about 0.5 g (N) m(-2). Emission of N as NOx (i.e., NO + NO2) was estimated at 2.5 g (N) in 2, equivalent to 30% of applied fertilizer nitrogen. The corresponding annual emission of NOx nitrogen from São Paulo State sugar cane burning was >45 Gg N. In contrast to mechanized harvesting, which does not require prior burning of the crop, manual harvesting with burning acts to recycle nitrogen into surface soils and ecosystems.

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In this work, the spatial variability model of CO2 emissions and soil properties of a Brazilian bare soil were investigated. Carbon dioxide emissions were measured on three different days at contrasted soil temperature and soil moisture conditions, and soil properties were investigated at the same points where emissions were measured. One spatial variability model of soil CO2 emissions was found for each measurement day, and these models are similar to the ones of soil properties studied in an area of 100 x 100 m. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

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

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A pon stimulation by contralateral, ipsilateral or bilateral noise, the medial olivocochlear efferent tract changes the amplitude of otoacoustic emissions relative to the tested ear, reducing or removing it; this resulted in a reduction/suppression effect of otoacoustic emissions. Differences in patterns of elimination/reduction of otoacoustic emissions between ears have been documented worldwide; there are, however, no Brazilian studies investigating the effect of lateral dominance.Aims: To compare the effect of the presence of deletion/reduction of otoacoustic emissions and their amplitude relative to lateral dominance in normal hearing adults.Methods: A clinical and experimental study. The sample comprised 75 individuals. The methodology was conventional - linear click intensity of 60 dB SPL; white noise was contralateral stimulation at 60 dB SPL.Description of results: There were no statistically significant differences between right and left ear results, in terms of asymmetry of the degree of otoacoustic emissions and the presence of suppression/reduction.Conclusion: There is no lateral dominance in the degree of otoacoustic emissions in the presence of suppression/reduction in the study population.

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The pulsating combustion process has attracted interest in current research because its application in energy generation can offer several advantages, such as fuel economy, reduced pollutants formation, increased rate of convective heat transfer and reduced investment, when compared with other new techniques of combustion. An experimental study has been conducted with the objective of investigating the effects of combustion driven acoustic oscillations in the emission rates of combustion gases, especially carbon monoxide and nitrogen oxides, and soot presence in partial premixed flames in confined partially premixed liquefied petroleum gas flames. The results basically showed that a more uniform fuel/air mixture due to the presence of an acoustic field increases the NOx emissions in operations close to stoichiometric equivalence ratios and the frequency is the most important parameter. Carbon monoxide and soot reduced significantly.

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The generation expansion planning (GEP) problem consists in determining the type of technology, size, location and time at which new generation units must be integrated to the system, over a given planning horizon, to satisfy the forecasted energy demand. Over the past few years, due to an increasing awareness of environmental issues, different approaches to solve the GEP problem have included some sort of environmental policy, typically based on emission constraints. This paper presents a linear model in a dynamic version to solve the GEP problem. The main difference between the proposed model and most of the works presented in the specialized literature is the way the environmental policy is envisaged. Such policy includes: i) the taxation of CO(2) emissions, ii) an annual Emissions Reduction Rate (ERR) in the overall system, and iii) the gradual retirement of old inefficient generation plants. The proposed model is applied in an 11-region to design the most cost-effective and sustainable 10-technology US energy portfolio for the next 20 years.