409 resultados para Pureza radioquímica


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A glicerol quinase é uma proteína tetramérica que cataliza a fosforilação do glicerol a glicerol-3-fosfato, composta por quatro subunidades - sua análise eletroforética fornecerá apenas uma banda se for constatada a sua pureza num gel não desnaturante - e sua reação com o glicerol é dependente de magnésio e de ATP. A eletroforese de proteínas utiliza como suporte um gel de poliacrilamida, que é formado pela polimerização de monômeros de acrilamida ao longo da sua cadeia e ligações cruzadas de cadeias pela inclusão de um co-monômero bifuncional apropriado, usualmente a N,N’ – metileno-bis-acrilamida ou apenas Bis . A eletroforese de proteínas mais comum é a que utiliza SDS para um gel de poliacrilamida desnaturante. O SDS é um sal chamado Dodecil Sulfato de Sódio que tem por característica se ligar a cadeia proteína nos resíduos de aminoácidos apolares, deixando com a carga negativa, sendo assim, toda proteína fica com carga total negativa, migrando para o anodo na eletroforese. As técnicas de purificação utilizadas foram ultrafiltração e precipitação com ácido tricloro acético, etanol gelado e sulfato de amônio. A dupla precipitação com etanol resultou na recuperação de maior quantidade de proteínas. A coloração do gel com prata foi mais sensível do que Comassie blue. O gel de eletroforese mostrou quatro bandas, correspondentes às quatro subunidades da glicerol quinase quando revelados com prata em gel de SDS-PAGE.

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Atualmente o uso indiscriminado e não criterioso de antibióticos está causando um aumento alarmante de resistência bacteriana chegando a ser considerado um problema de saúde pública. Nesse contexto, a utilização do peptídeo antimicrobiano (PAM) Hylina-a1 proveniente de uma rã da fauna brasileira está sendo estudado. Sua atuação na membrana celular dificulta a ocorrência de resistência bacteriana. No entanto, o uso de PAMs ainda apresenta problemas principalmente relacionados à disponibilidade, eficácia e toxicidade. A fim de contornar esses problemas, este trabalho teve como objetivo principal avaliar a incorporação deste peptídeo a um sistema líquido cristalino nanoestruturado com capacidade de regular a liberação e proteger os peptídeos da degradação química e física mantendo a bioatividade. O sistema líquido cristalino foi preparado com fosfatidilcolina de soja (FS), oleato de sódio (OS) e Tween 20 (TW), colesterol (CHO) e tampão fosfato, sendo que alguns pontos apresentaram fases líquido-cristalinas do tipo lamelar. Para os estudos posteriores foi escolhido um ponto com características visuais de viscosidade apropriadas ao uso tópico e a este se incorporou o peptídeo. A obtenção do peptídeo por meio da SPFS foi viável, obtendo-se materiais com alto índice de pureza. No ensaio de reologia a formulação apresentou-se como fluido pseudoplástico não–Newtoniano, com a presença de tixotropia; sendo possível também confirmar a incorporação do peptídeo ao sistema. A espectroscopia UV e a CLAE comprovaram que a maior parte do peptídeo é incorporada à fase líquido-cristalina do sistema. Os ensaios biológicos mostraram que o sistema líquido-cristalino possui atividade contra bactérias muito menor que o peptídeo livre. Este fato foi atribuído à baixa liberação do peptídeo pelo sistema

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O emprego significativo de polímeros na sociedade moderna causou um grande desenvolvimento tecnológico em torno de sua produção a partir do petróleo. Contudo a limitação crescente de disponibilidade e as altas sucessivas do preço do petróleo têm estimulado, cada vez mais, novas pesquisas no desenvolvimento de biopolímeros provenientes de recursos renováveis. O biopolímero dextrana tem origem da conversão do substrato promovida pela enzima dextranasacarase que é secretada por micro-organismos principalmente pertencentes à família Lactobacillaceae. O objetivo desta pesquisa tem por meio do levantamento bibliográfico reunir conteúdos relacionados ao biopolímero dextrana, a enzima dextranasacarase, os micro-organismos produtores e suas aplicações industriais. Devido a algumas características da dextrana (Hidrofobicidade, estabilidade, pureza e habilidade de formar soluções claras e estáveis, entre outras), a mesma apresenta um grande leque de aplicações na indústria farmacêutica, alimentícia, petroquímica e química. As pesquisas que vinculam a dextrana às aplicações industriais estão em plena expansão e sabendo que a produção de dextrana é proveniente de recursos naturais renováveis e de origem microbiana, o momento atual é favorável para um aumento de sua produção, causando a valorização deste biopolímero no mercado nacional e internacional

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The wood of the gender Eucalyptus occupies a prominence place in relation to other cellulose sources, due to its chemical composition, its low cost, abundance and availability. The dissolving pulp obtaining occurs basically starting from three stages: prehydrolysis of the wood following by cooking and finally by the bleaching process. In the dissolving pulp production is necessary a pretreatment stage for the hemicelluloses removal. Among the chemical cooking processes, the Kraft process is the most used for cellulosic pulps production starting from eucalyptus, in the additive presence or not. The anthraquinone uses in the pulping process has as main purposes increasing the delignification rate as well as protecting the pulp regarding the degradation of the polysaccharide chains. The ECF bleaching process consists of the purification of the pulp through bleaching agents, being excepted the elementary chlorine. The dissolving pulp is a pulp of high a-cellulose content and purity destined to the cellulose derivatives production as carboxymethyl cellulose, nitrocellulose and microcrystalline cellulose. The production of a certain product, as well as its final application, is determined by the chemical properties of the pulp. The present work had as purpose producing cellulosic pulp with kappa number around 9 destined to the production of dissolving pulp in way to evaluate the use of the anthraquinone (AQ) in the Kraft process according to the chemical properties of the obtained pulps. It has been still intended developing an effective technology of bleaching for the high purity and quality dissolving pulp production. The prehydrolysis was accomplished in laboratory rotational autoclave for 30 minutes at 170ºC in the water:wood rate 3,5:1 (L:kg). The Kraft/AQ pulping were accomplished in laboratory rotational autoclave being initially modified the active alkali load (10, 13, 16 and 19%) at sulfidity of 25% ...

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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

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Pós-graduação em Engenharia Mecânica - FEB

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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In experimental conditions, cutting forces were studied during turning of green alumina billets, including their correlation with surface aspects of the workpiece. The correlation between cutting power and the removal rate are important parameters for defining the design of ceramic products, since inadequate parameters can produce excessive surface damage to the workpiece. This study examined the forces obtained during turning of alumina workpieces with 99.8% purity in their green state, by means of a three-point dynamometer, evaluating the cutting, feed and depth forces, using a cermet tool under constant machining conditions. Variables were compared with the forces, including surface finish, tool wear and temperature during machining. In the study, it was found that the depth of cut had no significant effect on the surface quality, and the cutting speed and feed influencing the finish. However, preliminary tests for selecting the cutting conditions showed that unsuitables cutting speeds and feeds generate severe damage to the workpiece surface. The best condition was 1.00 mm depth of cut, and the forces increasedfor with each pass performed, with the feed force the variable with greatest increases in relation to the cutting and depth forces, and wear of the cutting tool directly influenced the surface finish, generated by the highly abrasive nature of the alumina particles of the green compact. It is emphasized that the alumina in its green state showed high abrasive effect on the cutting tool during the turning process and the surface finishing of the green workpiece had a direct influence on the sintered workpiece.

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The objective of this study was to assess families and highlight the superior progenies of sugarcane originating from 38 biparental crosses for the following attributes: tons of cane per hectare (TCH), tons of biomass per hectare (TBIOH), brix (% cane juice), fiber content, purity, pol and total recoverable sugar (TRS). The data were analyzed by mixed model REML / BLUP in the REML (Restricted Maximum Likelihood) allowed us to estimate genetic parameters and BLUP (best linear unbiased prediction) to predict the additive and genotypic values. The best family for the attributes TCH and TBIOH was 41, whose parents are cultivars IACSP022019 x CTC9. In individual selection for TCH, the plant number 3 of Block 2, the crossing 78, showed the best results. To TBIOH the plant number 33, Block 1, family 41, showed the best results. Families 40, 41, 43, 68, 69, 79, 91, 92 and 147, were higher for the variables brix, pol, purity, and ATR, where as 85 families, 147, 148, 149, 161, 163, 177, 178, 179, and 183 were higher for fiber. The family 147 whose parents are IACSP042286 x IACSP963055, showed three progenies ranked among the top ten for both brix, and for fiber, which identifies the combination as a potential source of progenies for bioenergy production.

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Although the popularization of astronomy in the last decade and the International Year of Astronomy, celebrated in 2009, there's a great lack in respect of quality instruments for astronomical disclosure. Thinking in this research about it, we intend to recuperate and elucidate a technique long forgotten: the metal mirror amateur telescope, once was done in the first reflecting telescopes. However, with the resources available today and given the high purity of the materials, our results were better than that obtained by the pioneers. We developed and built a large aperture telescope (250 mm diameter) and very bright (focal ratio = 4.0), versatile and portable. In our study was described step by step the process to fabricate the telescope. Through its first images captured of the Moon, we can illustrate its versatility both for use in outreach events and for use in amateur astronomy, because it is a primary focus capture system and can run registration of various astronomical events

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The sol-gel process is a technique based on the hydrolysis and polycondensation of metal alkoxides have been investigated as an alternative for the preparation of vitreous or glassceramic materials, for allowing the obtaining of high-purity materials at low temperatures, and to obtain hybrid materials with different compositions. When ORMOSILs are doped with nanoparticles, are called nanocomposites, and its functionality arises when electrons confined in scale three-dimensional structures near zero are excited. In principle, such materials exhibit discrete energy level, with peaks in the absorption spectrum. Therefore, the glasses doped semiconductor nanocrystals are important candidates for the preparation of optical filters with sharp cut-off, and are being exploited commercially for coloring glasses. This study evaluates the optical properties presented by hybrid films of silica doped with copper nanoparticles. The matrix was prepared using the alkoxides 3-glycidoxypropyltrimethoxysilane (GPTS) and tetraethylorthosilicate (TEOS) doped with Cu2O and hydrolyzed under reflux conditions in two different acidic conditions (HCl and HBr). After thermal treatment at temperatures between 100 °C and 170 °C and/or under the action of commercial black light radiation, CuCl and CuBr present in the hybrid film are transformed into nanoparticles of CuCl or CuBr. The UV-VIS absorption identified the absorption bands, and its variation

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Eletronicalceramics are used in many applications such as: multilayer capacitor, transducer, pyroelectric sensors and electrooptic devices. In recent years there has been a growing demand for eletronicalceramics with better performance and functionality. This demand has accelerated the development of synthesis techniques to produce powders with well-defined particle size, shape and crystallinity. The eletronicalceramics in the form of bulk are determined by their performance characteristics of the powders used and the preparation process. So, physical and chemical properties of powders, such as chemical control of stoichiometry, purity, homogeneity, particle size and shape should be observed when choosing the methods of synthesis. Among the techniques used so far, the polymeric precursor method, also known as Pechini, has been considered ideal for the preparation of nanosized powders. Thus, this research project aims to use the polymeric precursor method to prepare powders of lithium tantalate and lanthanum tantalate, with good chemical stability. In this aspect is proposed to investigate the effects of variation of the concentration of europium about the properties of tantalate because doping with Eu3 + indicates that they may occupy different sites in the crystal structure, as in the case of LiTaO3. Effects of things like occupation sites, stability of phases and formation temperature have been previously investigated by the group, which motivated the formulation of this project. Our proposal aims to introduce the Eu3 + LaTaO4 and LiTaO3 and study the structural and optical properties of the powders obtained by Pechini method, as well as correlate these studies with the electrical properties of the material, mainly the Ironelectricty Hysteresis.