929 resultados para Contamination for lead


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Purpose - The purpose of this paper is to provide information on lubricant contamination by biodiesel using vibration and neural network.Design/methodology/approach - The possible contamination of lubricants is verified by analyzing the vibration and neural network of a bench test under determinated conditions.Findings - Results have shown that classical signal analysis methods could not reveal any correlation between the signal and the presence of contamination, or contamination grade. on other hand, the use of probabilistic neural network (PNN) was very successful in the identification and classification of contamination and its grade.Research limitations/implications - This study was done for some specific kinds of biodiesel. Other types of biodiesel could be analyzed.Practical implications Contamination information is presented in the vibration signal, even if it is not evident by classical vibration analysis. In addition, the use of PNN gives a relatively simple and easy-to-use detection tool with good confidence. The training process is fast, and allows implementation of an adaptive training algorithm.Originality/value - This research could be extended to an internal combustion engine in order to verify a possible contamination by biodiesel.

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Composite made of Lead Zirconate Titranate (PZT) ceramic powder and castor oil based polyurethane (PU) were prepared in the thin film form with 0-3 connectivity by spin coating. The composite films were obtained in the thickness range of 100 mum to 300 mum using 33-vol.% of ceramic. The samples mechanical resistance. The material was characterised by dielectric spectroscopy, thermally stimulated discharge current (TSDC), hysteresis measurements and laser-intensity-modulation method (LIMM). The pyroelectric coefficient at 343 K was 7x10(-5) C.m(-2) K-1 for the sample poled with 10 MV/m at 373 K for Ih. The results show that this new composite can be used as suitable piezo and pyroelectric sensors.

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

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

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

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

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This study is conducted in the estuary of the rivers Jundiaí and Potengi, one of the most important estuaries of Rio Grande do Norte, which suffers a strong anthropogenic influence from neighboring cities. According to Resolution 344/2005 environments that have high concentrations of metals such as arsenic, cadmium, lead and mercury need ecotoxicological tests. This study aims to evaluate the heavy metals contamination in the estuary through analysis of sediment collected at four points distributed from Macaíba to Natal city, and in the crab Uçá, Ucides cordatus. The study aims also to evaluate the effects of sediment toxicity in the tests organisms Leptocheirus plumulosus. To obtain data about the concentrations of heavy metals in the environment, sediments were collected in January and May 2011 and crab Uçá was collected in June 2011. On the other hand the monitoring was carried out through toxicological tests with sediment collected from July to October 2011. During the collection of sediment samples the physico-chemical parameters of water (dissolved oxygen, pH, chloride, turbidity, conductivity and temperature) were measured by using multi-parametric probe (TROLL 9500). It was possible to identify contamination by metals such as lead, cadmium, arsenic and copper both in the sediment and in the Uçá crab, which characterizes that the consumption of this crustacean may be a risk to human health. Once the concentrations of metals were identified, toxicology tests were performed and revealed toxic effect to organisms in at least one of the four months studied. Point 2 was classified as toxic in three of the four months studied . The heavy metal contamination is a risk to the environment, to aquatic organisms and to the community which survives of resources taken from the environment

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Quilombo communities remaining are groups marked by insufficient public assistance and characterized by living in rural and conducting economic activities such as agriculture. The development on a sustainable basis is important to ensure strategies for economic growth and environmental preservation. This work aims to study the remaining Quilombo Capoeira Black community, located in the municipality of Macaíba, Rio Grande do Norte, considering the principles of sustainable development. Attempt to respond to what level such community can be considered sustainable from an analysis of their social practices. The methodological procedures used consisted of a literature review and documentary, questionnaires, conducting semi-structured interviews and direct observation. The final results show that the family farm has characteristics that approximate the principles of sustainable development, including the diversification of labor, food production with less environmental damage and strengthening the rural environment, and indicate that the main economic activities practiced in Capoeira dos Negros community are agriculture, manufacturing of cassava flour and brick manufacturing, which, in turn, are linked to negative environmental impacts, such as sedimentation pond, groundwater contamination, air pollution and soil erosion. What lead to the conclusion that the social practices of the community are not in line with the dimensions of sustainable development. It is hoped that the survey results provide subsidies for development and implementation of public policies

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O presente trabalho estudou a intoxicação acidental por arsênico em um lote de 24 vacas Girolando, as quais tiveram acesso a pasto pulverizado com herbicida à base de metano arsonato ácido monossódico (MSMA). Os bovinos apresentaram apatia, anorexia e diarreia profusa. Foram necropsiados na fazenda dois animais de 14 que morreram. Os principais achados macroscópicos foram úlceras abomasais e congestão renal. No exame microscópico, as principais lesões observadas foram abomasite e omasite necro-hemorrágica multifocal acentuada e, nos rins, necrose tubular difusa. As concentrações médias de arsênico em vacas com sinais clínicos foram 1,19±0,40, 10,52±2,16 e 76,06±48,37ppm no sangue, leite e fezes, respectivamente. Os níveis de arsênico encontrados em dois animais necropsiados foram 25,58 e 23,85ppm em fígado, e 28,71 e 35,94ppm em rins, respectivamente. No feto de uma vaca necropsiada, os níveis de arsênico mensurados no fígado e rim foram 9,0 e 8,92ppm, respectivamente. A concentração de arsênico no capim do piquete pulverizado foi 111,58ppm. No Brasil, o uso MSMA na composição de pesticidas e herbicidas é permitido somente para uso agrícola, mas não pecuário. A utilização desse ou de outros produtos à base de arsênico na pecuária pode causar altos índices de mortalidade no rebanho, além de diminuição da produção e contaminação de produtos de origem animal.

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Tradicionalmente, os limites de tolerância biológica são utilizados exclusivamente para a promoção e a preservação da saúde dos trabalhadores, não sendo aplicados com fins diagnósticos. Entretanto, com relação a algumas intoxicações profissionais, o assunto é polêmico. Neste artigo, defende-se a utilização do limite de tolerância aplicado atualmente no Brasil à plumbemia como um critério importante para a realização do diagnóstico da intoxicação profissional pelo chumbo. Argumenta-se que, em oposição ao tradicional critério clínico, deve-se abordar o problema do diagnóstico da intoxicação pelo chumbo sob um ponto de vista epidemiológico, utilizando-se o atual valor do limite de tolerância para a plumbemia como um marcador de risco relativo significativamente aumentado.

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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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Oxidative stress is considered a possible molecular mechanism involved in Pb neurotoxicity. Considering the vulnerability of the developing brain to Pb neurotoxicity, this study was carried out to investigate the effects of low-level developmental Pb exposure on brain regions antioxidant enzymes activities. Wister dams were exposed to 500 ppm of Pb, as Pb acetate, or to 660 ppm Na acetate in the drinking water during pregnancy and lactation. The activities of superoxide dismutase (SOD), glutathione peroxidase and glutathione reductase were determined in the hypothalamus, hippocampus and striatum of male pups at 23 (weaned) or 70 days (adult) of age. In the Pb-exposed 23-day-old pups, the activity of SOD was decreased in the hypothalamus. Regarding adults, there was no significant treatment effect in any of the enzymes and regions evaluated. Based on the present results, it seems that oxidative stress due to decreased antioxidant function may occur in weaned rats but it is suggested that this should not be the main mechanism involved in the neurotoxicity of low-level Pb exposure. (C) 2001 Elsevier B.V. Ireland Ltd. All rights reserved.

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Perinatal Pb exposure may modulate arterial tone through nitric oxide (NO) and cyclooxygenase products. To investigate this, Wistar dams received 1000 ppm of Pb or sodium acetate (control) in drinking water during pregnancy and lactation. Curves were constructed in phenylephrine-precontracted intact and/or denuded rings of thoracic aortas of weaned (23-day-old) male pups from their responses to N-omega-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor) and ACh in the absence or presence of indomethacin (10(-5)M, cyclooxygenase inhibitor) or L-NAME (3 x 10(-7)M and 3 x 10(-4)M). Blood lead concentration and systolic blood pressure (SBP) were higher in intoxicated than control pups (blood lead mu g/dl: control < 3.0, Pb 58.7 +/- 6.5*; SBP mmHg: control 111.4 +/- 2.3, Pb 135.5 +/- 2.4*). In L-NAME-treated rings maximal responses increased in Pb-exposed rats, and were higher in intact than in denuded aortas (contraction [% of phenylephrine] intact: control 184.3 +/- 23.7, Pb 289.1 +/- 18.3*; denuded: control 125.1 +/- 4.5, Pb 154.8 +/- 13.3*). ACh-induced relaxation in intact aortas from Pb-exposed rats presented rightward shift in L-NAME presence (EC50 x 10(-7)M: control 1.32 [0.33-5.18], Pb 4.88 [3.56-6.69]*) but moved left under indomethacin (EC50 x 10(-7)M: control 8.95 [3.47-23.07], Pb 0.97 [0.38-2.43]*). *p < 0.05 significant relative to the respective control; N = 7-9. Endothelium removal abolished ACh-induced relaxation. Perinatal Pb exposure caused hypertension associated with alterations in the production and/or release of basal and stimulated endothelium-derived relaxing factors-NO and constricting cyclooxygenase products. These findings may help explain the contribution of NO and cyclooxygenase products to the etiology and/or maintenance of Pb-induced hypertension and could ultimately lead to therapeutic advantages in plumbism.