963 resultados para Metais


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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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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)

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A Geografia da Saúde é um eixo temático dentro da ciência geográfica preocupada com as questões pertinentes à saúde ambiental e a saúde do coletivo. As contribuições dos geógrafos para o estudo da Saúde tem sido de grande valia, indo para além da análise espacial das práticas em saúde como também investigando e analisando os fatores determinantes ao risco a saúde e, inversamente, ao bem estar-estar do social e ambiental. Dentro deste contexto, esta monografia se propõe a uma investigação confirmatória a cerca de uma contaminação ao meio ambiente por metais pesados, neste caso, a contaminação por chumbo por uma extinta fábrica de lingotes de chumbo situada no município de Caçapava, SP. O chumbo é um metal que não possui função fisiológica conhecida ao corpo humano. Devido a características físicas e químicas favoráveis, esse metal foi largamente explorado pelo setor industrial e hoje, no mundo todo, temos exemplos de casos de contaminação tanto da população e do ambientel, por ser altamente tóxico. Caçapava possui mais um infeliz exemplo de contaminação ambiental por metais pesados, decorrente de uma fábrica que produzia o chumbo secundário e que atualmente está fechada por ordem judicial, abandonada e com toneladas de escória de chumbo armazenada de modo irregular, fato que está colaborando para uma contaminação residual naquele ambiente... (Resumo completo, clicar acesso eletrônico abaixo)

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This Final Paper had as it main goal to make a thermoanalytical study of lighter trivalent lanthanides (Lanthanum, Cerium, Praseodymium, Neodymium, Samarium and Europium) with the Ibuprofen ligand (nonsteroidal anti-inflammatory) that have a general formula LnL3.nH2O, on solid state, where Ln are the Lanthanides, L is the Ibuprofen ligand and n = number of water molecules of hydration that went from 1,0 to all the compounds. In order to characterize this compounds, it has been used the thermoanalytical techniques TG-DTA (thermogravimetry - Diferential Thermal Analysis) and DSC (Diferential Scanning Calorimetry), Fourier transformed infrared spectroscopy (FTIR) and complexometric titration with EDTA. Through the TG-DTA technique, it has been possible to set the thermal stability of the compounds, the number of thermal decomposition steps and temperatures that ocurred that also provided stoichiometry to the synthesized compounds. The DSC technique has shown the enthalpy of dehydration of the samarium and europium compounds, it was not possible to see it in the other compounds due to a endothermic peak on the DSC curve not being formed. In the case of neodymium, a thermal event ocurred, in which it could be a oxidative decarboxylation right after the dehydration. The infrared was utilised to study the carboxilate groups streches, and so, suggest a ligand metals compound coordination, that to this present paper has been a bidentade bridged coordenation. At last, the complexometric tritation was used to very the ammount of metal present in each compound, and so, verify if the proposed stoichiometry was according to the theory

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The treatment of domestic and industrial effluents through Wastewater Treatment Plants (WTPs) generates a residue termed sewage sludge, rich in organic matter, high-volume, occasionally containing pathogens and heavy metals. The sludge generation can minimize the benefits brought by the treatment of sewage, because this residue does not always receive appropriate treatment before final disposal. The disposal is another problem related to sludge. Landfills generally does not have physical space and alternatives such as the use in agriculture requires an intense treatment that could be in many cases operational or economic unfeasible. The objective of this work is the theoretical research about the processes of stabilization of the sludge by anaerobic digestion and the methanogenic activity during the process. Through analysis of each step and contemplating each relevant factor in anaerobic digestion process in order to optimize them, we proposed a theoretical model of reactors capable of stabilize the sludge, reduce its volume and eliminate pathogens. The obtained configuration consists of two anaerobic reactors connected in series. The first one operates in the range mesophilic temperature (35 ° C) and has higher hydraulic retention time (25 days) working primarily in the stabilization of organic matter present in the sludge and producing biogas, whereas the second one operates in the thermophilic range (55 ° C) in order to eliminate pathogens, and to reduce the volume. The hydraulic retention time in the second reactor is lower (10 days). Both mesophilic and thermophilic processes were efficient in what was proposed, promoting the stabilization of organic matter present in the sludge and significant reduction of pathogens. As a final step with the sludge previously digested, it is indicated a final dehydration... (Complete abstract click electronic access below)

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The macrostructure of an alloy solidification in the raw state is of utmost importance due to its influence on mechanical properties. A structure showing columnar grains is generally undesirable in most applications of cast products and grain refining aims to suppress the formation of these grains and get a fine-grained equiaxed structure that improves the supply of liquid metal and the mechanical properties, as yield strength and tensile strength limit, as well as the tendency of formation of hot cracks. The type and size of grains formed are determined by chemical composition, cooling rate and the use of inoculum for grain refining. Titanium and boron are the major refiners in the aluminum industry and can be added to the molten metal in the form of alloys such as Al-Ti, Al-Ti-B or Al-B. In this paper we will discuss the information obtained from cooling curves and first derivative of the cooling curve to obtain the thermal parameters that influence the process of grain refining alloy AA 356.0

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In order to to research, the region of Perau, base metal mineralization, Grupo Votorantim Metals conducted a soil sampling on targets predetermined holding its chemical analysis. These reviews have been provided by the company for this work was to evaluate the potential use of these data pedogeochemical multi-element for refinement of the work of geological mapping. We selected six targets: Varginha, Salvador, Guararema Taquara Lisa and Coffin of Mendes, in the municipalities of Adrianople, Cerro Azul and Tunas do Paraná, located in Vale do Ribeira (PR). Both have about 10 km2 and situated in the geological context of the Fold Belt Terrane and the Massif de Joinville. The main rock types are present metasedimentary rocks of low to medium grade metamorphic, interspersed the amphibolites ortoderivados, both belonging to the Complex Perau, gneisses and migmatitic Complex. Applied to the geochemical data descriptive statistical techniques (variogram, kriging and histogram). From the correlation between the distributions of elements with the geological data, we could assess the potential of the proposed methodology.

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Fuel cells are a very promising solution to the problems of power generation and emission of pollutant to the environment, excellent to be used in stationary application and mobile application too. The high cost of production of these devices, mainly due to the use of noble metals as anode, is a major obstacle to massive production and deployment of this technology, however the use of intermetallic phases of platinum combined with other metals less noble has been evaluated as electrodes in order to minimize production costs and still being able to significantly improve the catalytic performance of the anode. The study of intermetallic phases, exclusively done by experimental techniques is not complete and demand that other methods need to be applied to a deeper understanding of the behavior geometric properties and the electronic structure of the material, to this end the use of computer simulation methods, which have proved appropriate for a broader understanding of the geometric and electronic properties of the materials involved, so far not so well understood.. The use of computational methods provides answers to explain the behavior of the materials and allows assessing whether the intermetallic may be a good electrode. In this research project was used the Quantum-ESPRESSO package, based on the DFT theory, which provides the self-consistent field calculations with great precision, calculations of the periodic systems interatomic force, and other post-processing calculations that points to a knowledge of the geometric and electronic properties of materials, which may be related to other properties of them, even the electrocatalytic. The electronic structure is determined from the optimized geometric structure of materials by analyzing the density of states (DOS) projected onto atomic orbital, which determines the influence of the electrocatalytic properties of the material... (Complete abstract click electronic access below)

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

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Located in Apiaí, Vale do Ribeira, southern region of São Paulo state, the Usina do Calabouço areas (CIEM / CPRM) and Morro do Ouro (Parque Municipal do Morro do Ouro), were targeted for stud ies due to its old buildings, respectively a foundry in lead ore, called Experimental de Chumbo e Prata (Usina Calabouço), and a gold mine with processing plant of the gold-bearing ore produced there. Nowadays, the areas are used for public visitation, and in both places the rests of the buildings remains. Particularly in the CIEM/CPRM, due to the materials witch was produced before, it can suggest the existence of anomalous amounts of the involved metals (CIEM / CPRM) and possible contaminations by chemical products used in the improvement of the auriferous ore (P. M. Morro do Ouro). These potential contamination were confirmed with geochemical survey of soils and current sediments accomplished in both areas, for the elements arsenic, cadmium, lead, copper, mercury, silver and zinc, which were used as parameters guiding values for soil and groundwater the state of São Paulo (CETESB), and watershed values stipulated by CPRM (poor, background and anomalous), in it rising geochemistry during Folha Apiaí's execution (SG-22-X-B-V).

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The AA356 alloy is an alloy widely used in the automotive industry and aerospace due to its excellent mechanical properties. Refining the structure of eutectic silicon aluminum alloys is a fairly common practice in the foundry through treatment known as modification. This can be achieved by modifying agent adding chemicals such as contained in groups I and IIa of the periodic table and rare earths (europium, céreioi, praseodymium, neodymium, etc.). Has the ability to modify the structure of the eutectic, but only sodium and strontium produce an action modifier strong when used in low concentrations. The modifying effect of the shafts turn silicon into a fibrous form and branched surrounded by metallic matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. In this work will be obtained ingots with and without the modifier type Al-10% Sr, made in sand molds and are generated and analyzed cooling curves and also the study of the macrostructure and microstructure of the solidified material. It was found that by adding the Al-Sr made shorten the solidification time and lower the grain size

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The Roosevelt-Domain Aripuanã that by Filho et al 2004 is characterized by a metavolcanic sedimentary sequence, containing acidic to interemediary metavolcanic rocks and clastic and chemical sediments, deformed and metamorphosed at low grade, with U-Pb age of 1.743 +- 4 Ma, (by Granito Zé do Torno), and circumscribed bodies of granites late to post-orogenic (Aripuanã)...

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In the eld of synthetical materials, often called in the literature as organic/molecular conductors or charge-transfer salts, the most prominient examples are the quasi onedimensional systems (TMTTF)2X and (TMTSF)2X, where TMTTF, TMTSF and X refers to tetrametiltetratiafuvaline, tetrametiltetraselenafuvaline and a monovalent anion (X = PF6