Determinação de Cd, Cu, Ni, Pb e Zn em águas marinhas oriundas da Bacia Potiguar utilizando a técnica de difusão em filmes finos por gradiente de concentração (DGT)

The DGT technique has been used to determine and better understand the dynamics and bioavailability of metals in the sea near to marine outfalls. In this work, the DGT was assessed for the determination of Cd, Pb, Cu, Zn and Ni in marine water samples from Potiguar Basin in its conventional aspect (binding agent, Chelex-100 and diffusive agent: Diffusive polyacrylamide gel (D) and restrictive (R)) and determination of Pb and Cd through its alternative aspect (binding agent: Saccharomyces cerevisiae immobilized in agarose gels and diffusive agent: 3MM Chromatography Paper). The deployment curves for long periods of immersion in the sample, showed a good linear correlation for the conventional aspect to Zn (D: R²=0.9586, R: R²=0.9444), Ni (D: R²=0.9789, R: R²=0.9286) and Cu (D: R²=0.764, R: R²=0.8143), and alternative to Pb (R²=0.9228) and Cd (R²=0.9673). The results of the organic and inorganic composition analysis in conventional aspect, showed that for every element there is no significant fraction of organic compounds in the sample. In addition, considering the alternative aspect, the comparison of obtained and expected masses suggests that some of the Pb is not labile and that the main retention mechanism of Pb for S. Cerevisiae occurs through ion exchange

Confecção e caracterização de filmes finos de boro para a medida da taxa de reação 10B(N, a)7LI na terapia por captura de nêutrons pelo boro

The Boron Neutron Capture Therapy (BNCT), based on the 10B(n,α)7Li reaction, represents a promising modality for the treatment of cancers that are resistents to conventional treatments. So, it is necessary to find drugs (boron compounds) with high selectivity for each type of cancer, the neutrons source should be well characterized and the rate of 10B(n,α)7Li reaction should be measured with great accuracy as possible. This study aimed to develop a method for manufacturing thin films of boron, for measure the 10B(n,α)7Li reaction, and analyze the uniformity of the films. Five thin films of boron were manufactured with three different concentrations of boric acid, heated to transform the acid in boron, irradiated with thermic neutrons coupled to CR-39 detectors, in BNCT line at the reactor IEA-R1 IPEN/CNEN, São Paulo. After the irradiation, the detectors were chemically attacked with NaOH to reveal the tracks. The methodology presented is effective because it resulted in deposition of boron as thin film enabling the quantitative analysis of 10B(n,α)7Li reaction. The analysis of the uniformity of density of the induced tracks in CR-39 shows that, in most of the films, there is no uniformity in surface distribution of boron, but when the film is divided, we obtain some uniform sectors

Estudo das propriedades físicas em materiais vítreos do sistema 50B2O3 - 15CuO - 20Li2O - 15X (X= Na2O, K2O, RbCI e Cs2O)

The increasing demand for devices for solid state applications in many technological areas has resulted in a high demand for new materials. Among these material have the advantage of being manufactured with different chemical compositions, and may have physical properties equal to or higher than the corresponding crystalline material. The aim of this paper was to produce borate glass system 50B2O3 – 15CuO – 20Li2O – 15X (X = Na2O, K2O, RbCl e Cs2O) to analyze the influence of the atomic radius of alkali in the physical properties of this glass system. The glasses were synthesized by the process of melting and molding. The characteristic temperatures were determined by the technique of scanning calorimetry (DSC). The non-crystalline was determined by x-ray diffraction. In order to determine the molar volume a density measurement by using the Archimedes method was used. The structural characterization was carried out using the technique of infrared spectroscopy

Avaliação da membrana de troca aniônica DE 81 como ligante ba técnica de difusão em filmes finos por gradientes de concentração (DGT) para a determinação de Cromo VI

It is known that there is a wide variety of bioavailable trace metals in aquatic systems, and its determination is fundamental to predict impacts to organisms in these environments. However, the determination of the total concentration of chemicals in aquatic systems, despite its importance, does not provide necessary information for decision making or even may lead to misinterpretation of the procedures and potential risks to the system in question. This study aimed to use the technique of diffusion in thin films by concentration gradients (DGT) to evaluate the anion exchange membrane Whatman DE 81 as binder alternative in determining Cr (VI). Experiments were carried out to determine the diffusion coefficients for the material used diffusion (agarose gel). The behaviors of the binders were analyzed before the main variables of the systems, immersion time, pH and ionic strength. Then was made the assessment of potential interferences, to finally proceed with testing using actual samples in the laboratory and in situ

Avaliação da membrana P81 como agente ligante da técnica de difusão em filmes finos por gradiente de concentração (DGT) para determinação de mercúrio em sistemas aquáticos

Worldwide environmental degradation is an undesirable byproduct resulting from the increasing demand for natural resources. Water sources are suffering intense contamination since they usually receive a huge amount of domestic and industrial effluents - which are mostly wasted without proper treatment - inserting a large number of pollutants in the environment, heavy metals included. Mercury holds great toxicological importance because, under some physicochemical conditions in a water environment, Hg (II) ion turns into methylated compounds stemming from this element, such as methylmercury CH3Hg, which is highly toxic for the aquatic community in which bioaccumulation occurs. Nowadays passive sampling techniques are being developed to enable the analytical procedures which are applied in environmental monitoring. Diffusive gradients in thin-films technique (DGT) has been proven an interesting tool for the determination of labile metal species due to its in situ application. The DGT technique consists of a piston-like device on which the following series of agents is disposed: a binding agent (conventionally Chelex 100 resin), a diffusive agent, usually a polyacrylamide gel, and a membrane filter. Nevertheless, the agents conventinally used for this technique don't usually show satisfactory results in mercury sampling. The main goal of this study was to evaluate the phosphate-treated cellulose membrane (Whatman P 81), an alternative material, as binding agent in the DGT to determine labile mercury fractions in aquatic systems. In this context, we conducted a study of the behavior of this material in relation with system variables, pH and ionic strength. Afterwards we performed immersions of the DGT devices in real and enriched samples and in situ aiming the determination of mercury

Um estudo teórico e experimental de nanoestruturas de 'ZnS': propriedades físicas e químicas

Pós-graduação em Química - IQ

Deposição de filmes finos de SnO2 e GaAs, visando confecção de dispositivos baseados na heterojunção SnO2/GaAs

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

Avaliação da Saccharomyces cerevisiae como agente ligante na técnica de difusão em filmes finos por gradiente de concentração (DGT) para a determinação de metilmercúrio

Sabendo-se do potencial de toxicidade do mercúrio, mais especificamente de sua forma orgânica, o metilmercúrio (MeHg), faz-se necessária a busca por métodos analíticos eficientes e precisos para a determinação e especiação do metal. A técnica de difusão por gradiente em filmes finos (DGT) já vem sendo utilizada para tal fim de maneira eficiente tendo apresentado resultados satisfatórios em diversos estudos. Porém, a utilização de ligantes alternativos aos convencionais, que tornem a aplicação da técnica menos custosa em termos laborais e financeiros, faz-se importante para um monitoramento constante e eficiente do metilmercúrio no ambiente. No presente trabalho buscou-se avaliar o potencial da levedura Saccharomyces cerevisiae imobilizada em agarose em combinação com a poliacrilamida como agente difusivo para determinação seletiva de MeHg. Os resultados demonstraram-se positivo, com um coeficiente de difusão médio de 7,03 ± 0,77 x 10-6 cm2 s-1. Os resultados demonstraram também baixa influencia do pH, força iônica e outros íons na retenção do analito pelos dispositivos. As recuperações de Hg2+ demonstraram-se insatisfatórios, evidenciando a seletividade dos dispositivos

Fabricação e caracterização elétrica de células solares a partir de filmes finos orgânicos

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

Estudo das propriedades físicas de sistemas ferroelétricos com estruturas tipo Aurivillius

Pós-graduação em Ciência dos Materiais - FEIS

Determinação in situ de metilmercúrio e mercúrio (II) em sistemas aquáticos nas proximidades de refinarias de petróleo, utilizando a técnica difusão em filmes finos por gradiente de concentração (DGT)

Pós-graduação em Geociências e Meio Ambiente - IGCE

Aplicação de doses de vinhaça sob desenvolvimento vegetativo de pastagem degradada e propriedades físicas do solo

The experiment was conducted in the experimental field of the University of GoiásUEG, UNU Ipameri - GO with the objective of evaluating the effect of different doses of vinasse on the vegetative development of degraded pasture and soil physical properties in two seasons. The pasture used in the experiment was in a state of degradation, and had eight years of formation. The experimental design was randomized blocks consisted of eight treatments and four blocks, totaling 32 experimental units. We evaluated the following soil physical properties: density the soil, particle density, total porosity, infiltration velocity, soil water. We also evaluated the following parameters of vegetative development of grassland: green and dry mass of shoots, effective depth of the root system, the grass height. The results were submitted to analysis of variance at 5% significance level and after we performed regression testing. The vinasse promoted significant effect on all parameters related to vegetative development of both grazing during the rainy season as in the dry. In this case, a model that best fit the dataset vegetative pasture was quadratic. It appeared that the vinasse different doses did not cause changes in the physical properties of the soil.

Propriedades físicas, químicas, antimicrobianas e biológicas de cimentos endodônticos com óxido de cálcio e resina salicilato

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Determinação de vanádio em águas usando a técnica de difusão em filmes finos por gradientes de concentração

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades físicas e mecânicas de cimentos de ionômero de vidro encapsulados e não encapsulados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)