278 resultados para manganês


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O tratamento de esgotos sanitários e o seu posterior reúso, tornou-se uma alternativa viável para a irrigação, atividade que utiliza em torno de 70 % de toda a água consumida no planeta. Nesse sentido, o objetivo deste estudo foi monitorar durante todo o ciclo do trigo, os teores de Ferro e Manganês, bem como valores de pH e condutividade elétrica da água residuária utilizada para irrigação da cultura por gotejamento. A água residuária utilizada no estudo foi proveniente da Estação de Tratamento de Esgotos (ETE) da cidade de Botucatu-SP. No período de maio a outubro de 2011 a amostragem da água residuária foi realizada semanalmente, na saída da ETE. Foram determinados os seguintes parâmetros: Boro (B), Cobre (Cu), Ferro (Fe), Manganês (Mn) e Zinco (Zn), segundo metodologia adaptada de Malavolta et al. (1997). O pH e a condutividade elétrica (CE) foram determinados com auxilio de um pHmetro e condutivímetro, respectivamente. Não foi observado teores de Fe e Mn e valores de pH que comprometessem o sistema de irrigação, ou seja, que apresentasse alto potencial de risco de obstrução de tubulações e emissores (gotejamento). Os valores de CE indicam que a água residuária pode ser usada no solo, sempre que houver grau elevado de lixiviação, sem maior comprometimento das culturas.

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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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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Snakes from Bothrops genus are responsible for more than 90% of the ophidian accidents in Brazil. One of the main complications from this kind of accident is muscular necrosis, which is related to the action of phospholipases A2 and metalloproteases, two groups of enzymes found in the venom of these animals. Although this complication cannot be solved by serum therapy administration, a great number of studies have been performed with the attempt to know the pharmacological sites of these toxins aiming, in the future, the development of complementary treatments to serum therapy. This work proposes structural studies of bothropic phospholipases A2 (PLA2s) in the presence of ions relevant to their activity, using the X-ray crystallography technique. Recently, it was demonstrated ions, as manganese, calcium and others, interfere in the biological activity of the PLA2s. Particularly, Lys49-PLA2s in the presence of manganese ions have miotoxicity reduced. Asp49-PLA2s show catalytic activity dependent of calcium, although structural studies with a miotoxic Asp49-PLA2, BthTX-II, suggest a possible catalytic mechanism independent of calcium. Therefore, co-crystallization of BthTX-II in the presence of calcium ions and of PrTX-I in the presence of manganese ions were performed. Comparative structural studies among obtained results and others already published in the literature were performed aiming a better understanding of the structure-function relationship of these toxins. The BthTX-II with the presence of calcium do not show this ion in the loop of coordination of calcium, presence necessary to develop the catalyses. After comparison of this model with the native one, only one distortion was found, but no apparent relationship with the residues responsible for its activity. In the PrTX-I structure, regions candidates of manganese ions were also found... (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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The aim of this experiment was evaluate the effect of the bioestimulant administered in grafted and non-grafted japanese cucumber (Cucumis sativus L.) plants, under greenhouse conditions, in gas exchanges during the development of the plant and in the increase of yield. The experiment was carried out in the experimental area of Agronomic Sciences University of UNESP, Campus of Botucatu, São Paulo State, Brazil. The experiment design was completely randomized, in a factorial arrangement of 2x5, grafted and non-grafted plants and 5 treatments with bioestimulant: control, indolbutyric acid 0,0005% + citocinine 0,0009% + gibberelic acid 0,005% 250 mL ha-1; indolbutyric acid 0,0005% + citocinine 0,0009% + gibberelic acid 0,005% 375 mL ha-1; indolbutyric acid 0,0005% + citocinine 0,0009% + gibberelic acid 0,005% 500 mL ha-1; Yuca extract (Yucca elephantipes) + manganese + iron + copper + sulfur 375 mL ha-1 applied 15 days after the transplant, in intervals of 7 days between the applications, via leaf. The effect of the treatments were evaluated through the observations of the following characteristics: production of fruits (number and mass), average mass of the fruit and measures of gas exchanges. It can be concluded that indolbutyric acid 0,0005% + citocinine 0,0009% + gibberelic acid 0,005% 250 mL ha-1 increased CO2 assimilation rate and the water efficiency, influencing in addition to increase the quantity of the fruits

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The studies of this work aimed to determine the labile fractions of manganese (Mn) in natural and drainage water samples collected around the Osamu Utsumi uranium mine, located in the municipality of Caldas, south-central region of Poços de Caldas- MG, using the technique of diffusion gradient in thin films (DGT). The DGT devices were mounted with Chelex-100 resin, polyacrylamide-agarose hydrogel (conventional porosity) and cellulose acetate membrane. The device were deployed up to 48 hours in six water samples collected from different areas around the uranium mine (075, 076, 022-E, 025-E, 014, and 041). The DGT devices immersed in each sample were gradually removed after 4, 8, 12, 24 and 48 hours. The pH of the samples ranged from 3.0 to 10.5, which influenced the lability and the sampling of the analyte by the Chelex-100 resin. The results showed a linear relationship between accumulated mass and sampling time (immersion curve) for samples 014 and 025-E (pH between 6 and 8) suggesting the ability of the DGT technique for sampling the analyte. The results obtained for samples 075 and 076 (pH<5) and samples 041 and 022-E (pH around 10) were characterized by nonlinear relationships. The values obtained by DGT were compared with Solid Phase Extraction (SPE) technique using Chelex-100. For samples 014 and 025-E, there was a good agreement between the results obtained by both techniques

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The study of mechanical properties of high-alloy special steels is of great interest of the steel industry due to the great demand by companies that manufacture automotive components of high criticality, and also because of its high commercial value. However, the development of this type of alloy metals demand highly technical knowledge. Among these extremely important kinds of steel, the subject which is the interest of this study is the special steel modified by niobium. The manganese and niobium are the main alloying elements in the composition of these steels, both of them increase the stability of the austenite region, however, manganese increases the hardenability and tensile yield strength, and niobium increases the mechanical strength and promotes refining the grain. The mechanical characterization of steel SAE 1312 modified the niobium was made in order to gain a better understanding of the influence on the mechanical properties caused by aging at different temperatures and for different reductions in the drawing of gauge material. This characterization was made by means of tensile test and hardness. This material showed an increase in yield strength and hardness when gauge with large reductions during the wiredrawing, but when subjected to aging temperatures higher than 300 ° C had a slight loss of these properties

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Os biossurfactantes apresentam inúmeras vantagens, como baixa toxicidade, biodegradabilidade e alta estabilidade, mas não são amplamente utilizados devido ao custo de produção. A utilização de substratos baratos, linhagens mutantes que associados à otimização das condições de cultivo pode levar a uma redução nos custos, possibilitando assim a substituição dos surfactantes sintéticos pelos biológicos. Uma maneira empregada para maximizar a produção dos biossurfactantes é a limitação de nutrientes. Os esforços empregados nesse sentido são direcionado para as proporções carbono: nitrogênio, entretanto os efeitos dos elementos traços são pouco conhecidos. Devido a esses fatores, o presente trabalho avaliou a importância dos seguintes elementos traços: ferro, zinco, cobalto, cobre, manganês e do sal citrato de sódio dihidratado, nas fermentações realizadas utilizando o mutante de Pseudomonas aeruginosa LBI 2A1. Para tanto foram realizadas fermentações em frascos Erlenmeyer, onde se utilizou diferentes concentrações desses elementos. A influência dos mesmos na produção de ramnolipídios foi constatada, uma vez que a produção desse biotensoativo foi aumentada em mais de três vezes alterando apenas a concentração de um único elemento traço (Fe). Os experimentos realizados permitem, também, inferir a respeito das melhores concentrações desses micronutrientes para a produção de ramnolipídios

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This study evaluated the effect of physical and chemical activation on the speed of penetration of hydrogen peroxide bleaching agents present in different concentrations through the enamel and dentin. One hundred and twenty bovine incisors were used, which were obtained enamel/dentin discs of the buccal surface, with 6 mm in diameter. The samples were divided into six groups: G1 - Hydrogen Peroxide Gel 20%, G2 - Hydrogen Peroxide Gel 20% with light activation, G3 - Hydrogen Peroxide Gel 20% with Manganese Gluconate; G4 - Hydrogen Peroxide Gel 35%; G5 - Hydrogen Peroxide Gel 35% with the light activation and G6 - Hydrogen Peroxide Gel 35% with Manganese Gluconate. The specimens were placed in a transparent support on which there was a substance sensitive to hydrogen peroxide immediately below and in contact with the specimen. After the procedures for applying the gel for each group, one video camera was positioned and operated to monitor the time of penetration of peroxide in each specimen. The recording ended after changing the color of the fluid revealed in all specimens and times were noted for comparison. ANOVA analysis showed that concentration and type of activation of bleaching gel significantly influenced the diffusion time of hydrogen peroxide (P 0.05). 35% hydrogen peroxide showed the lowest diffusion times compared to the groups with 20% hydrogen peroxide gel. The light activation of hydrogen peroxide decrease significantly the diffusion time compared to chemical activation. The highest diffusion time was obtained with 20% hydrogen peroxide chemically activated. The diffusion time of hydrogen peroxide was dependent on activation and concentration of hydrogen peroxide. The higher concentration of hydrogen peroxide diffused through dental tissues more quickly

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A contaminação do solo pelo descarte de substâncias tóxicas adquiriu, nos últimos anos, maior atenção da comunidade científica a qual tem alertado a população dos países, em geral, para as conseqüências, em especial, as patologias que podem ocorrer quando estas substâncias adentram nossa cadeia alimentar. Neste trabalho procurou-se apresentar as fontes de contaminação e a toxicidade do cádmio, do chumbo, do mercúrio e do manganês, quando estes se encontram em níveis elevados no solo e nos mananciais superficiais e subterrâneos. Com relação aos três primeiros metais, sua alta dosagem pode provocar, no ser humano, diversos tipos de câncer, lesões no estômago e pulmões, além de alterações importantes nos sistemas imunológico e nervoso central. O manganês, um dos metais mais comuns da crosta terrestre, largamente utilizado pela indústria e disponibilizado, em grandes quantidades no meio ambiente, em doses elevadas pode causar doenças pulmonares e neurológicas.