999 resultados para Espectroscopia de Mössbauer


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This study aimed to analyze the phytoremediation potential of Eichhornia crassipes in natural environments, optimize the extraction process of crude protein from plant tissue and, obtain and characterize this process in order to determine its viability of use instead of the protein sources of animal and/or human feed. For this, it has been determined in Apodi/Mossoró river water the concentration of ammonium ions, nitrite, nitrate, calcium, magnesium, potassium, iron, copper, manganese, zinc, nickel, cobalt, sodium, aluminum, cádmium, lead, and total chromium; It was determined in plant tissue of aquatic macrophytes of Eichhornia crassipes species present in Apodi/Mossoró River the moisture content, ash, calcium, magnesium, potassium, iron, copper, manganese, zinc, nickel, cobalt, sodium, aluminum, cadmium, lead, total chromium, total nitrogen and crude protein. It was also determined the translocation factor and bioaccumulation of all the quantified elements; It was developed and optimized the extraction procedure of crude protein based on the isoelectric method and a factorial design 24 with repetition; It was extracted and characterized the extract obtained by determining the moisture content, ash, magnesium, potassium, iron, copper, manganese, zinc, nickel, cobalt, sodium, cadmium, total nitrogen and crude protein. And finally, it was also characterized the protein extract using Thermogravimetric Analysis (TG), Derived Thermogravimetric (DTG), Differential Scanning Calorimetry (DSC), Infrared Spectroscopy (FT-IR) and jelly-like electrophoresis of polyacrylamide (SDS -PAGE) to assess the their molecular weights/mass. Thus, from the results obtained for the translocation and bioaccumulation factors was found that the same can be used as phytoremediation agent in natural environments of all quantified elements. It was also found that the developed method of extraction and protein precipitation was satisfactory for the purpose of the work, which gave the best conditions of extraction and precipitation of proteins as: pH extraction equal to 13.0, extraction temperature equals 60 ° C, reaction time equals to 30 minutes, and pH precipitation equals to 4.0. As for the extract obtained, the total nitrogen and crude protein were quantified higher than those found in the plant, increasing the crude protein content approximately 116.88% in relation to the quantified contente in the vegetal tissue of macrophyte. The levels of nickel and cadmium were the unique that were found below the detection limit of used the equipment. The electrophoretic analysis allowed us to observe that the protein extract obtained is composed of low polypeptide chains by the molecular and phytochelatins, with 6 and 15 kDa bands. Analysis of TG, DTG, DSC and FT-IR showed similarities in protein content of the obtained extracts based on different collection points and 9 parts of the plant under study, as well as commercial soy protein and casein. Finally, based on all these findings, it was concluded that the obtained extract in this work can be used instead of the protein sources of animal feed should, before that, test its digestibility. As human supplementation, it is necessary to conduct more tests associated with the optimization process in the sense of removing undesirable components and constant monitoring of the water body and the raw material used

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Foi desenvolvido um método para detectar e quantificar misturas de corantes em sucos artificiais em pó fabricados no Brasil, de diferentes marcas e sabores. Foram estudados 6 corantes artificiais: amarelo tartrazina, amarelo crepúsculo, vermelho ponceau 4R, vermelho bordeaux S, vermelho 40 e azul brilhante presentes de forma unitária ou em misturas nos sucos com sabores laranja, tangerina, maracujá, abacaxi, limão e uva. A identificação dos corantes nas amostras foi feita através da comparação com os espectros dos padrões, utilizando-se a análise por infravermelho médio e pelos respectivos valores de absorção máxima nos comprimentos de onda relativos aos padrões e valores de referência na literatura. Também foram estudados os perfis de decomposição térmica por termogravimetria, termogravimetria derivada e calorimetria diferencial exploratória dos corantes e dos sucos em pó, sendo determinados os teores de umidade, de matéria orgânica e de cinzas. O teor de umidade encontrado não ultrapassou 4% para todas as amostras de suco analisadas. Com relação ao teor de matéria orgânica obteve-se para 57% dos sucos analisados um teor médio de 51,3% e para 43% das outras amostras obteve-se uma média de 67,2 %. Os resultados obtidos para o teor de cinzas indicaram que 29% das amostras apresentaram um teor de 26,7% para esse parâmetro enquanto 71% das amostras apresentaram um teor de cinzas de 46,4%. Os resultados obtidos por análise térmica mostraram-se adequados considerando-se que para obter os resultados pelo método tradicional há um investimento maior de tempo, de pessoal envolvido e de material, além da proteção ao meio ambiente. Para a análise por espectroscopia de absorção molecular foi proposta uma equação simplificada para a determinação de cada corante na mistura utilizando-se a lei de Beer. Para validação, empregou-se a espectroscopia de absorção molecular no visível, onde foi investigada a influência dos interferentes (TiO2 e açúcar) presentes nas amostras de sucos, os testes de fotodegradação e a avaliação do efeito do pH. Para quantificação tomou-se como referência 512 amostras sintéticas contendo um e dois corantes (1,5625 a 25,000 mg L-1) para obtenção das curvas analíticas que foram aplicadas à análise dos sucos em pó. Os resultados indicaram que o teor máximo do amarelo crepúsculo foi encontrado nos sucos com os sabores laranja, tangerina e manga que correspondeu a 25,6% da ingestão diária aceitável (para ser ultrapassada corresponderia a ingestão de 4 copos). O teor máximo encontrado para o amarelo tartrazina nos sucos foi para o sabor maracujá que correspondeu a 8,5% da ingestão diária aceitável, (para ser alcançado corresponderia a ingestão de 12 copos). O método proposto foi testado e validado com sucesso para amostras de sucos em pó sendo de simples execução e de rapidez na obtenção dos resultados

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Bifunctional catalysts based on zircon oxide modified by tungsten (W = 10, 15 and 20 %) and by molybdenum oxide (Mo= 10, 15 e 20 %) containg platinum (Pt = 1%) were prepared by the polymeric precursor method. For comparison, catalysts the tungsten base was also prepared by the impregnation method. After calcinations at 600, 700 and 800 ºC, the catalysts were characterized by X-ray diffraction, fourier-transform infrared spectroscopy, thermogravimetric and differential thermal analysis, nitrogen adsorption and scanning electron microscopy. The profile of metals reduction was determined by temperature programmed reduction. The synthesized catalysts were tested in n-heptane isomerization. X-ray diffractogram of the Pt/WOx-ZrO2 and Pt/MoOx-ZrO2 catalysts revealed the presence of tetragonal ZrO2 and platinum metallic phases in all calcined samples. Diffraction peaks due WO3 and ZrO2 monoclinic also were observed in some samples of the Pt/WOx-ZrO2 catalysts. In the Pt/MoOx-ZrO2 catalysts also were observed diffraction peaks due ZrO2 monoclinic and Zr(MoO4)2 oxide. These phases contained on Pt/WOx-ZrO2 and Pt/MoOx-ZrO2 catalysts varied in accordance with the W or Mo loading and in accordance with the calcination temperature. The infrared spectra showed absorption bands due O-W-O and W=O bonds in the Pt/WOx-ZrO2 catalysts and due O-Mo-O, Mo=O and Mo-O bonds in the Pt/MoOx-ZrO2 catalysts. Specific surface area for Pt/WOx-ZrO2 catalysts varied from 30-160 m2 g-1 and for the Pt/MoOx-ZrO2 catalysts varied from 10-120 m2 g-1. The metals loading (W or Mo) and the calcination temperature influence directly in the specific surface area of the samples. The reduction profile of Pt/WOx-ZrO2 catalysts showed two peaks at lower temperatures, which are attributed to platinum reduction. The reduction of WOx species was evidenced by two reduction peak at high temperatures. In the case of Pt/MoOx-ZrO2 catalysts, the reduction profile showed three reduction events, which are attributed to reduction of MoOx species deposited on the support and in some samples one of the peak is related to the reduction of Zr(MoO4)2 oxide. Pt/WOx-ZrO2 catalysts were active in the n-heptane isomerization with high selectivity to 3-methyl-hexane, 2,3- dimethyl-pentane, 2-methyl-hexane among other branched hydrocarbons. The Pt/MoOx-ZrO2 catalysts practically didn't present activity for the n-heptane isomerization, generating mainly products originating from the catalytic cracking

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In the present study we compute the atmospheric parameters (Teff , log g and vmic, [Fe/H]) and chemical abundance of 16 ions (Fe I, Fe II, O I, Si I, Na I, Mg I, Al I, Ca I, Ti I, Co I, Ni I, Rb I, Zr I, Ba II, La II and Cr I) for 16 solar-like stars with masses between 0:8 and 1:2 Mfi aproximatedly, including 10 planet-host stars detected by the CoRoT Space Mission. For this study, we use data from the ESO public archive: (i) high resolution spectra (R 47000) from the UVES spectrograph on the VLT/UT2-ESO (for 7 stars, covering the wavelength range 3450-4515 Å and 5500-9400 Å) and (ii) high resolution spectra from HARPS spectrograph on the La Silla-ESO 3.60 m telescope (for 9 stars, covering the wavelength range 4200-6865 Å). Our spectral analysis is based on MARCS models of atmosphere and Turbospectrum spectroscopic tools. On the base of the computed parameters, the referred abundances appears to follow the same behavior of the solar curve abundances. Further, one observes a signifficant correlation between the abundance ratio [m/Fe] and condensation temperature (Tc) of refractory elements (Tc > 900 K). The behavior of the projected rotational velocity (v sin i) versus the computed abundances [m/Fe] is also analyzed, presenting no clear trends. This study oers additional constraints to trace the evolutive history of solar-like stars with planets, including the search for chemical dierences between stars with and without transit planets and anomalies in the studied abundances

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In this work we have developed a way to grow Fe/MgO(100) monocrystals by magnetron sputtering DC. We investigated the growing in a temperature range among 100 oC and 300 oC. Structural and magneto-crystalline properties were studied by different experimental techniques. Thickness and surface roughness of the films were investigated by atomic force microscopy, while magneto-crystalline properties were investigated by magneto-optical Kerr effect and ferromagnetic resonance. Our results show that as we increase the deposition temperature, the magneto-crystalline anisotropy of the films also increases, following the equation of Avrami. The best temperature value to make a film is 300 oC. As the main result, we built a base of magnetoresistence devices and as an aplication, we present measurements of Fe/Cr/Fe trilayer coupling. In a second work we investigated the temperature dependence of the first three interlayer spacings of Ag(100) surface using low energy electron diffraction. A linear expansion model of crystal surface was used and the values of Debye temperatures of the first two layers and thermal expansion coefficient were determinated. A relaxation of 1% was found for Ag(100) surface and these results are matched with faces (110) and (111) of the silver. iv

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In this work we obtain nickel ferrite by the combustion synthesis method whcih involves synthesising in an oven at temperatures of 750oC, 950oC and 125oC. The precursors oxidizing used were nickel nitrate, ferric as an oxidizing and reducing urea (fuel). After obtaining the mixture, the product was deagglomerated and past through a 270 mesh sieve. To assess the structure, morphology, particle size, magnetic and electrical properties of nanoparticles obtained the samples were sintered and characterized by x-ray distraction (XRD), x-ray fluorescence spectroscopy (FRX); scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometer (MAV ) and electrical permittivity. The results indicated the majority of phase inverse spinel ferrite and Hematite secondary phase nickel and nickel oxide. Through the intensity of the distraction, the average size of the crystallization peaks were half-height width which was calculated using the Scherrer equation. From observing the peaks of all the reflections, it appears that samples are crystal clear with the formation of nanoparticles. Morphologically, the nanoferritas sintered nickel pellet formation was observed with three systems of particle size below 100mn, which favored the formation of soft pellets. The average size of the grains in their micrometric scale. FRX and EDS showed qualitatively the presence of iron elements nickel and oxygen, where through quantitative data we can observe the presence of the secondary phase. The magnetic properties and the saturation magnetization and the coercive field are in accordance with the nickel, ferrite where the curve of hysteresis has aspects of a soft material. Dielectric constant values are below 10 and low tangent loss

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

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O crescimento da hidroxiapatita - HA, tanto no meio biológico quanto em soluções aquosas como a Synthetic Body Fluid - SBF, ocorre em meio contendo, além dos elementos Ca e P, elementos-traços essenciais tais como: Mg2+, HCO3-, K+ e Na+. Alguns destes elementos são conhecidos como inibidores do crescimento da HA, como Mg2+ e HCO3-. Neste trabalho, estudou-se a influência dos íons K+ e Mg2+ na formação de apatitas sobre substratos metálicos de Ti c.p. previamente tratados com NaOH 5M. Os efeitos destes íons no recobrimento obtidos, antes e após o tratamento térmico a 800ºC, foram analisados por microscopia eletrônica de varredura - MEV, espectroscopia de energia dispersiva de raios-X - EDX, difratometria de raios-X - DRX e espectroscopia no infravermelho - IV e mostraram que o efeito inibitório do Mg2+ na formação da HA se manifesta após o tratamento térmico. Diferentemente, o crescimento cristalino da HA não foi afetado pela presença do íon K+. Além disso, a formação de apatita carbonatada se deu também em soluções que não continham o íon CO3(2-) em sua composição.

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

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