453 resultados para Metais - Fundição
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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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Alloy Al-7%Si-0,3Mg (AA356), having an excellent combination of properties such as low solidification shrinkage and good fluidity, good weldability, high wear resistance, high strength to weight particularly in the automotive and aerospace engineering. The refinement of the structure aluminum silicon eutectic alloy is a fairly common practice in the casting, through the treatment knows as modification. You can get the modification for the addition of chemicals and rare earths, these have the ability to modify the structure of the eutectic, but only sodium and strontium produce a strong action modifier when used in low concentrations. The modifying effect of silicon grain turns into a fibrous form branched and enveloped by the metal matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. This work will be obtained AA356 alloy ingots using two different types of molds: metal mold and sand mold. Macrographs will be made in ingots obtained for observation of the macrostructures obtained in both types of ingots. Will be sampled at strategic locations of the ingots to correlate microstructure and cooling rate. The results showed that the material of the ingot has a strong influence on the resulting micro-andmacrostructure
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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
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The industry produces rolled, starting to and passing through casting forming processes, for example, in the case in question the rolling. A large portion of rolled products are flat, these have specific characteristics during their production and properties after finished that must be analyzed. For this a study of these properties must be made in materials samples, in order to be able to first know the material in question or provide new properties to the material through the process of rolling flat products. In this way is interesting that the students of mechanical engineering have knowledge of rolling trials, and from this can better understand the behavior of rolled. With this purpose the project of a benchtop rolling mill for the rolling of flat is needed, this work is the project of a sizing of one rolling mill non-ferrous materials
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A espécie Eichhornia crassipes (Pontederiaceae) é uma macrófita aquática conhecida popularmente como aguapé. É utilizada na descontaminação de ambientes aquáticos poluídos, pois possui alta capacidade de absorver e tolerar elevadas quantidades de íons metálicos. Segundo estudos, o cádmio é um dos metais mais absorvidos por essa espécie, que apresenta maior acúmulo em raízes em relação às partes aéreas. O objetivo desse trabalho foi verificar se a produção de antocianinas do aguapé é alterada pela presença de íons Cd(II) nos tecidos. Foram realizados experimentos in vivo submetendo os espécimes à solução nutritiva contendo ou não íons cádmio. Os extratos metanólicos acidificados com HCl das raízes foram analisados por CLAE-UV e fracionados por CC (C18 e Sephadex), seguidos por CLAE semipreparativa. Após as análises por CLAE-DAD-EM foi possível propor a estrutura de duas antocianidinas: delfinidina e delfinidina substituída por um grupo metoxílico (C16H13O8, 333,0609)
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This study aims to determine the most suitable type of heat exchanger to be applied to the water cooling the mold of a continuous casting process. Basically been studied four types of heat exchangers: shell and tube operating in counterflow, shell and tube operating in parallel flow, plate type and operating counterflow and plates operating in parallel flow. Initially is displayed design of heat exchangers for the conditions of the proposed application. With the heat exchangers dimensioned comparisons were made in order to set the heat exchanger more suitable for application. In the study, one comes to the conclusion that the plate type heat exchangers operating shows counterflow major advantage for this application
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O impacto das atividades antropogênicas sobre o meio ambiente é um tema de grande relevância atualmente, atraindo a atenção da comunidade científica em geral, visto que essas atividades têm causado alterações significativas na qualidade da água, do solo e do ar. Dentre a ampla gama de poluentes resultantes das atividades humanas, merece destaque a classe dos metais pesados, os quais possuem propriedades tóxicas e genotóxicas, constituindo fatores de risco para o desenvolvimento de desordens neurodegenerativas, artrite e câncer nas populações expostas a estes contaminantes, bem como alterações nos ecossistemas contaminados. Neste sentido, o presente trabalho teve por objetivo avaliar o potencial citotóxico, genotóxico e mutagênico do níquel como contaminante, utilizando Allium cepa (Liliaceae) como organismo-teste, a fim de detectar possíveis efeitos deletérios em seu material genético. Estas avaliações foram feitas por meio da exposição de sementes de A. cepa a três soluções, com diferentes concentrações de níquel. Os resultados obtidos no primeiro biensaio e na repetição estão apresentados na forma de artigo científico, a ser submetido para revista especializada. O estudo dos efeitos do níquel em A. cepa foram importantes, uma vez que os dados da avaliação dos danos induzidos neste organismo modelo podem ser utilizados para a comparação com modelos animais, sendo possível assim, a inferência dos perigos aos ecossistemas e à população que está exposta a esse contaminante
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Measurement units are used almost automatically nowadays, but few people know the origin of the units of length (meter), mass (kilogram) and time (second). And do not care to know what were anciently units of which our ancestors used, the difficulties that existed to make a set of measures. The aim of this work is to make a historical approach, through various units of measure. They are old, unusual to others that have been forgotten since the standardization of meters, and is also discussed about the metric system Englih (Once and foot), AV system (eg pound grain) that are still used in some countries like United States and England, the Troy system consisting of units of measure for precious stones and metals (eg gold and diamond) are also cited some physical concepts as reference: inertial, non-inertial; mass: gravity, relativistic, inertial
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Solid-state compounds of general formula LnL3.nH2O, in wich Ln represents lanthanum, lanthanides and yttrium, L is ketoprofen, and n = 0,5 (Pr, Sm, Tb), 1 (La, Eu, Dy, Ho, Er, Tm, Lu) e 1,5 (Ce, Nd, Gd, Yb, Y) were synthesized. Simultaneous thermogravimetry-differential analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy and EDTA complexometry were employed to characterize these compounds. The TG-DTA and DSC curves provided information concerning the thermal behaviour and thermal decomposition of synthesized compounds. The experimental and theoretical infrared spectroscopic data suggested that ketoprofen acts as a bidentate ligand towards trivalent lanthanides and yttrium (III)