963 resultados para Metais


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Because of the great metallurgical advances, the welded tubes by HF / ERW (High Frequency / Electrical Resistance Welding) have played a more active role in the oil and gas, gradually replacing tubes produced by other processes (UOE, SAW, and others) to deep water applications, in high and extremely low temperatures, highpressure conditions and in highly corrosive environments. However, studies have revealed that defects in the welded joints are in one of main causes of failures in pipelines. Associated with damage external and the stringent requirements of this sector, the welded joints become particularly critical for his toughness and the determination of this particular property is fundamental. This study aims to evaluate the toughness of the HF / ERW pipes in HSLA steel API X70 class, used in pipelines transport systems of gas and oil from data obtained with CTOD tests (Crack Tip Opening Displacement). The main objectives of this project are: mechanical and microstructural characterization of steels API X70 manufactured in Brazil; and evaluation of the toughness of weld process by HF / ERW steel API X70 national. After having the tests done, mechanical, chemical and metallurgical, we have the conclusion that those pipe are in agreement to API 5L 42ª edition for X70MO and the toughness behaves like the expected

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Aluminum alloys are widely used in industry, because they combine different mechanical properties according to the alloying elements used in addition to thermal and mechanical treatments performed, resulting in materials with good weight/resistance relation. The 7XXX series alloys are worked heat treatable alloys commonly used in the aerospace industry, especially due to their high mechanical properties obtained after aging heat treatment, which increases the interest around 7075 alloy. Some studies with alloys which can be aged show that it is possible that cold word processes affect the results of aging. Thus, this study was intended to verify the influence of the aging process of AA 7075 alloy. There were three routes of aging with specimens previously treated thermally. In the first route T6 treatment was performed with a annealed specimen and other in solid solution. The second was the natural aging in a annealed specimen. In the last route was done aging by steps with a annealed specimen and other in solid solution with the intention to reduce the effects of natural aging. The results show that the routes 1 and 3 had similar hardness for all the samples, showing that the validity of Route 3 as an alternative and also the hardening did not affect the hardness at the end of the process, significantly reducing the time required for the highest hardness. Finally, natural aging was less effective in increasing hardness

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A contaminação de rios com metais pesados vêm aumentando nas últimas décadas em resposta ao crescimento do setor industrial e seus dejetos, que frequentemente são despejados no ambiente sem que o tratamento adequado seja realizado. As implicações ambientais da contaminação dos ecossistemas naturais de água doce com níquel ainda são mal compreendidas, entretanto, a demanda global por este metal e as descargas antrópicas provenientes do setor industrial só aumentam. Embora o níquel não seja considerado altamente tóxico como outros metais, ele tem a capacidade de ser bioacumulativo e é, portanto, potencialmente perigoso para os peixes. Assim, é importante que seja desenvolvida uma compreensão mais profunda da fisiologia básica do níquel em peixes, tanto como um nutriente essencial quanto como um agente tóxico. Desse modo, o presente estudo teve como objetivo a análise do potencial genotóxico e mutagênico do níquel em peixes da espécie Oreochromis niloticus (Cichlidae), e a comparação das concentrações utilizadas deste metal nos bioensaios com a concentração limite, estabelecida pelo Conselho Nacional do Meio Ambiente (CONAMA). A resolução 357/05 do CONAMA, para controlar e taxar os limites máximos de contaminantes na água define que o limite máximo da concentração total de níquel permitida em corpos de água doce é de 0,025 mg/L Ni. Assim, os organismos-teste foram expostos a três diferentes concentrações de cloreto de níquel diluído, sendo que, a primeira concentração foi de 0,0125 mg/L, ou seja, metade da concentração máxima definida pelo CONAMA. A segunda concentração utilizada, 0,025 mg/L é o próprio limite de concentração estabelecido pela resolução. Por fim, a terceira concentração utilizada foi de 0,050 mg/L, que consiste no dobro da concentração máxima total de níquel permitida em corpos de água doce... (Resumo completo, clicar acesso eletrônico abaixo)

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This work consists of preparation and characterization of glasses containing transition noble metals and the study of optical properties of such materials. The glasses were prepared by quenching of the glass melt followed by heat treatment and polishing of the monoliths. The structural characterization of glasses was made using differential thermal analysis, X-ray, Raman and infrared spectroscopies, while the optical properties were studied by UV-Vis and M-Lines spectroscopies. Preliminary results have shown that the color of the glasses is dependent on both concentration of silver and the melting temperature of the melt. Controlled heat treatments have been used to induce the crystallization of Ag nanoparticles within the glass. The study of crystallization was accompanied by electron microscopy and UV-Vis spectroscopy. Data from electron diffraction, as well as chemical analysis, EDX, were obtained using a transmission electron microscope. EDX data have shown that the atomic percentage of Ag is higher on the nanoparticle. X-ray diffraction was used in order to characterize the composition of the crystals and cubic AgCl was identified as the main crystallized nanophase obtained after annealing

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The mining research is a complex activity, which should preferably involve the combination of direct and indirect techniques of geological research. The increasing demand for base metals in domestic and international markets provide the revaluation of mineral occurrences, which can be converted into deposits and mines. This paper presents the results of the application of geophysical methods of electric resistivity and induced polarization in main foliation parallel to the arrangement of the area, in a deposit of oxides and hydroxides in massive and disseminated ores, docked in gneisses and quartzites, located in the municipality of Itapira, in the North of the State of São Paulo in Brazil. Inversion models indicate the predominance of high cargabilidade that partially coincide with low resistivity values. Integration of geophysical data made possible the drafting of sections of electric walking with cross-checking distance x depth, for detailing your target. The integrated analysis of geophysical and geological structural data leads to the conclusion that the primary mining suffers structural control with the regional foliation in ores

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Atualmente, é grande a quantidade de cursos d’água continentais que se encontram contaminados por poluentes, tais como produtos químicos, metais, esgoto e detergentes biodegradáveis. Tendo em vista o fato de a musculatura possuir um papel fundamental na realização do nado em peixes, sua importância se reflete em atividades como caça, fuga, procura pelo alimento, defesa, migração, etc. Alterações na estrutura muscular de peixes, que possam vir a ocorrer devido à presença de poluentes na água trarão sérias implicações para o modo de vida destes, especialmente no caso de Astyanax altiparanae que é uma espécie pelágica e nadadora ativa. Consequentemente, tem havido uma crescente preocupação em relação aos poluentes e os efeitos que estes podem ter sobre as populações de peixes que habitam esses ambientes aquáticos poluídos, uma vez que estes constituem uma das fontes de alimento mais importantes para certas populações humanas assim como a principal fonte de renda para comunidades pesqueiras. Sendo assim, pretendeu-se por meio do presente estudo, analisar e identificar possíveis alterações na estrutura morfológica da musculatura peitoral e caudal em peixes de pequeno porte como Astyanax altiparanae, bem como analisar a ocorrência de um possível envelhecimento precoce destas, que possam ter sido causados pelos poluentes contidos na água com detergente diluído, na água do Lago Azul, Rio Claro, SP, em comparação com a água pura do poço artesiano da UNESP – Campus Rio Claro que foi clorada de acordo com o modelo requerido pela SABESP e constituiu o grupo controle. A análise foi feita com base na comparação do grupo controle com aqueles expostos aos poluentes e foram utilizadas técnicas de histologia, histoquímica e fluorescência

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Contamination of rivers and lakes, waste disposed by infiltration into the soil as fertilizer, for example, has been highlighted around the world, since such compounds can contain toxic elements, causing changes in aquatic and/or terrestrial ecosystem. Due to the possible presence of these elements in these wastes, it is possible assess damage to organisms exposed through breaks in genetic material and mutations. In this sense, this work aimed at exploring the cytotoxic, mutagenic and genotoxic vinasse pontential, residue used as fertilizer, from the processing of sugar cane into alcohol, using fish (Oreochromis niloticus - Cichlidae) as a test organism. The individuals were exposed to different dilutions of vinasse in the water and later carried out analysis of their erythrocytes using the micronucleus test and nuclear abnormalities associated and the comet assay. In the first bioassay, tilapia exhibited 5% and 10% vinasse concentrations died after 48h. The number of micronucleated erythrocytes was statistically significant for the 1% vinasse concentration and also for nuclear abnormalities such as broken-egg and nuclear bud, when compared with negative and positive controls; were also significant lobed type erythrocytes, when compared to the negative control. The test results of the comet assay were not significant for 1% vinasse when compared to the negative control, due to the high rate of comets with damage control, which is unusual. The same was observed for changes as notched and blebbed type. In the second chemical analyzes conducted, the detection of heavy metals in the vinasse sample, charged only the presence of copper and chromium, the latter with a concentration 89 times higher than in the first test. Differentially the first bioassay, fish exposed to dilution of 5% did not die... (Complete abstract click electronic access below)

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When exhausted, the batteries are classified as hazardous waste because it has potentially toxic heavy metals and bio-accumulators, such as mercury, cadmium and lead in their internal composition functional. Due to the high level of danger, such waste should be properly designed to not allow theses chemical components to cause significant impacts on the environment. Thus, the recycling of waste in question is the best destination. In this context, was wanted to know, through a questionnaire in interview format, how the graduates of the Universidade Estadual Paulista Julio de Mesquita Filho of Rio Claro / SP are involved with this environmental issue. Since then, has been developed and implemented an environmental management for internal batteries

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The concentration of metal pollutants such as lead (Pb), has grown and developed in populated areas due to pollution and other human activities. Consequently, the potential for achieve this element food chain has also increased. Lead is very toxic to humans, especially to children, and exposure to lead can cause adverse health effects mainly on human nervous system, bone marrow and kidneys, interfering with chromosomal or genetic processes. This paper presents an overview of the main aspects related to environmental contamination by lead from battery plants. The assessment of an area contaminated by lead in Bauru-SP next a battery factory was reported in this work as well as the entire history of monitoring, classification and application of processes applied by CETESB since 2002. Analyzing the issue in its economic aspects, we found that the degradation of the environment is directly related to the development model adopted by the capitalist system, which is based on the law of supply and demand for products and services. The data presented indicate that Brazil still needs a broader policy where government agencies, industries and population through awareness can be united for the same purpose: to preserve life

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The lubricant oil used in engines of internal combustion must be, periodically, changed. Its mainly function in the engines is to reduce the friction between the pieces, but its presence also promotes the cleanness and the refrigeration of the equipment. These attributions, at the end of some cycles of operation, make the oil to be dirty, that is, full of contaminating substances such as water, gasoline, diesel, additives, oxidized hydro-carbons and rests of metals, not being recommended, therefore, its discarding in the environment. Thus, all the used lubricant oil that leaves the automobiles engine has been thrust, waiting for a solution. The pollution generated by the discarding of a ton of used oil per day in the soil or in the rivers is equivalent to a domestic sewer of 40 thousand of people. The indiscriminate burning of the used lubricant oil generates significant emissions of metallic oxides, besides other toxic gases, like the dioxin and sulphur oxides. In this context, the mean objective of this essay was to effectuate the rerrefine of the used lubricant oil, aiming the increase of its life cycle and consequently contributing for the reduction of the environmental pollution. According to the used process, it was possible to get a rerrefine oil, of good quality, which physicistchemistries properties are in compliance with the norms of NBR and ASTM

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The dating of sediments in lakes, estuaries and rivers through radionuclides, when applied in association with other analitic methods (heavy metals, organic contaminants, etc.) allows analyses of the anthropogenic interference in the environment along the years. A geochronology of a sediment core from Untersee in Lake Constance, one of the most important hydric resources of Europe, was established through the Pb-210 method and adopting the CRS parameter (Constant Rate of Supply). The Cs-137 was successfully used to give basis to the results, as its additional input occurred in Chernobyl’s accident can be used as a marker to the year 1986. Associating the dating with the cores depth, the average mass accumulation rate and the sedimentation rate for the site were assessed (0,14 g/cm²/year and 4 mm/year respectively).

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Um dos caminhos para identificar os contaminantes e seus efeitos em ecossistemas aquáticos é examinar a resposta de alguns organismos considerados bioindicadores. O presente projeto teve por objetivo avaliar a bioconcentração de cádmio e cobre pelo peixe de água doce Oreochromis niloticus (tilapia), visando, principalmente, estabelecer seu potencial bioindicador de contaminação destes metais em ambientes fluviais.Dentre os vários metais pesados passíveis de contaminação ambiental, o cobre um elemento essencial e o cádmio um elemento não essencial, são altamente tóxicos, mesmo em níveis de concentrações muito baixos e podem se elevar quanto maior for o nível trófico do organismo, podendo chegar ao homem em teores magnificados. Em condições laboratoriais, foram determinadas as toxicidades aguda de Cu, de Cd, e de Cu+Cd em tilápias em períodos de 24 á 96 horas de exposição. A partir dos resultados obtidos nos testes de toxicidade aguda, foi estabelecida a dose letal que levou a óbito metade da população (CL50). Os valores encontrados para o presente estudo foram: CL50-96h para cobre – 3,53 mg/L;CL50-96h pra cádmio – 20,13 mg/L;CL50-96h para cobre combinado ao cádmio – 1,36 mg/L. Foram avaliadas as concentrações dos referidos metais nos fígados e nas brânquias. O presente estudo mostra que em linhas gerais o fígado acumulou mais metal do que as brânquias, e que o processo de absorção do cobre é mais rápido do que o do cádmio para a espécie de peixe testada. Os resultados obtidos mostraram que o cobre foi mais tóxico do que o que o cádmio, entretanto, a combinação de ambos metais apresentou maior toxicidade