Efeito da Gália como aditivo de sinterização em eletrólitos cerâmicos à base de céria sintetizados pelo método de complexação de cátions

Fuel cells are considered one of the most promising ways of converting electrical energy due to its high yield and by using hydrogen (as fuel) which is considered one of the most important source of clean energy for the future. Rare earths doped ceria has been widely investigated as an alternative material for the electrolyte of solid oxide fuel cells (SOFCs) due to its high ionic conductivity at low operating temperatures compared with the traditional electrolytes based on stabilized zirconia. This work investigates the effect of gallium oxide (Gallia) as a sintering aid in Eu doped ceria ceramic electrolytes since this effect has already been investigated for Gd, Sm and Y doped ceria electrolytes. The desired goal with the use of a sintering aid is to reduce the sintering temperature aiming to produce dense ceramics. In this study we investigated the effects on densification, microstructure and ionic conduction caused by different molar fraction of the dopants europium (10, 15 and 20%) and gallium oxide (0.3, 0.6 and 0.9%) in samples sintered at 1300, 1350 and 1450 0 C. Samaria (10 and 20%) doped ceria samples sintered between 1350 and 1450 °C were used as reference. Samples were synthesized using the cation complexation method. The ceramics powders were characterized by XRF, XRD and SEM, while the sintered samples were investigated by its relative density, SEM and impedance spectroscopy. It was showed that gallia contents up to 0.6% act as excellent sintering aids in Eu doped ceria. Above this aid content, gallia addition does not promote significant increase in density of the ceramics. In Ga free samples the larger densification were accomplished with Eu 15% molar, effect expressed in the microstructure with higher grain growth although reduced and surrounded by many open pores. Relative densities greater than 95 % were obtained by sintering between 1300 and 1350 °C against the usual range 1500 - 1600 0 C. Samples containing 10% of Sm and 0.9% of Ga reached 96% of theoretical density by sintering at 1350 0 C for 3h, a gain compared to 97% achieved with 20% of Sm and 1% of Ga co-doped cerias sintered at 1450 0 C for 24 h as described in the literature. It is found that the addition of gallia in the Eu doped ceria has a positive effect on the grain conductivity and a negative one in the grain boundary conductivity resulting in a small decrease in the total conductivity which will not compromise its application as sintering aids in ceria based electrolytes. Typical total conductivity values at 600 and 700 °C, around 10 and 30 mS.cm -1 respectively were reached in this study. Samples with 15% of Eu and 0.9 % of Ga sintered at 1300 and 1350 °C showed relative densities greater than 96% and total conductivity (measured at 700 °C) between 20 and 33 mS.cm -1 . The simultaneous sintering of the electrolyte with the anode is one of the goals of research in materials for SOFCs. The results obtained in this study suggest that dense Eu and Ga co-doped ceria electrolytes with good ionic conductivity can be sintered simultaneously with the anode at temperatures below 1350 °C, the usual temperature for firing porous anode materials

Caracterização morfológica e microestrutural da perovskita BaCexPr1-xO3 sintetizada a partir do método de complexação combinando EDTA/Citrato

In this study, binary perovskite (BaCexO3) were doped with praseodymium (Pr) to obtainment of the ternary material BaCexPr1-xO3. This material was synthesized by the complexation method combining EDTA/Citrate with the stoichiometric ratio of the element Praseodymium ranging from x = 0.1 to x = 0.9 in order to determine the influence of this rare earth element on the morphology and microstructure of the final powder. At first the material was synthesized based on the route proposed by literature (Santos, 2010), and then characterized by SEM and XRD, besides being refined by the Rietveld method. In the material that had lowest residual parameter, S, and lowest average size of crystal, pH variation of synthesis solution was made in order to identify the influence of this parameter on the morphology and microscopy of the final powder. The results show that addition of praseodymium did not directly influence the crystallographic and lattice parameters, keeping even the same orthorhombic structure of the binary material BaCexO3, according to Yamanaka et al (2003). Material type BaCe0,2Pr0,8O3 had lowest residual parameter (S=1.4) and lowest average size of crystallite (26.4 nm), being used as reference in the pH variation of synthesis solution for 9, 7, 5 and 3, respectively. Variation of this parameter showed that when the synthesis solution pH was decreased to below 11, there was an increase in the average size of crystals, for pH 9, about 58.3%, for pH 7 (30.3 %), for pH 2 (2.3%) and for pH 3 (42%), indicating that the value initially used and quoted by Santos (2010) was the most coherent

Obtenção de ferrita de cobalto através de dois métodos de síntese: método de complexação combinando EDTA/Citrato e método hidrotérmico

In this work it was synthesized and characterized the cobalt ferrite (CoFe2O4) by two methods: complexation combining EDTA/Citrate and hydrothermal investigating the influence of the synthesis conditions on phase formation and on the crystallite size. The powders were mainly characterized by x-ray diffraction. In specific cases, it was also used scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray fluorescence (XRF) and isotherms of adsorption and desorption of nitrogen (BET method). The study of the crystallite size was based on the interpretation of x-ray diffractograms obtained and estimated by the method of Halder-Wagner-Scherrer and Langford. An experimental design was made in order to assist in quantifying the influence of synthesis conditions on the response variables. The synthesis parameters evaluated in this study were: pH of the reaction medium (8, 9 and 10), the calcination temperature (combined complexation method EDTA/Citrate 600°C, 800°C and 1000°C), synthesis temperature (hydrothermal method 120°C, 140°C and 160°C), calcination time (combined complexation method EDTA/Citrate - 2, 4 and 6 hours) and time of synthesis (hydrothermal method 6, 15 and 24 hours). By the hydrothermal method was possible to produce mesoporous powders with high purity, with an average crystallite size up to 7 nm, with a surface area of 113.44 m²/g in the form of pellets with irregular morphology. By using the method of combined complexation EDTA/Citrate, mesoporous powders were produced with greater purity, crystallite size up to 22nm and 27.95 m²/g of surface area in the form of pellets with a regular morphology of plaques. In the experimental design was found that the hydrothermal method to all the studied parameters (pH, temperature and time) have significant effect on the crystallite size, while to the combined complexation method EDTA/Citrate, only temperature and time were significant

Concentrados de ácidos graxos insaturados obtidos a partir de óleo de carpa (cyprinus carpio) utilizando o método da complexação com uréia

O presente trabalho teve como objetivo obter concentrados de ácidos graxos mono e poliinsaturados a partir do óleo branqueado de carpa (Cyprinus carpio), utilizando o método de complexação com uréia, e estabelecer as melhores condições através do estudo de seus parâmetros. Foi utilizado um planejamento experimental 23 para determinar os fatores que influenciam de forma significativa (nível de 95%) os experimentos da complexação com uréia, e verificar quais as faixas de valores desses fatores que apresentam os melhores resultados. Os fatores de estudo foram: relação de uréia-ácido graxo (2:1 e 6:1), temperatura de cristalização (4ºC e -12ºC) e tempo de cristalização (14 e 24 h). As respostas para análise estatística foram: rendimento da fração líquida (%Rend), percentual de ácidos graxos livres (%AGL) da fração líquida e o perfil de ácidos graxos. Conforme o estudo realizado, a relação uréia/AG se mostrou muito efetiva, de forma diretamente proporcional, na obtenção de concentrados de ácidos graxos monoinsaturados (AGMI) e poliinsaturados (AGPI). Pois, uma vez que ao aumentar a relação de uréia/AG resultou em um meio favorável para a inclusão dos ácidos graxos saturados (AGS) na cristalização da uréia. Por este motivo a relação (6:1) foi melhor para obter concentrados de AGMI+AGPI. A relação entre temperatura e rendimento de concentrados de ácidos graxos insaturados foi de forma inversamente proporcional, sendo que no menor valor (-12ºC) ocorreu a melhor separação de ácidos graxos saturados dos insaturados. O tempo foi significativo, porém com menor influência quando comparado com as demais variáveis de estudo. Devido a isso, o ganho em rendimento dos concentrados de ácidos graxos insaturados em relação ao custo operacional envolvidos no método de complexação com uréia não sugere que o maior tempo seja utilizado, sendo que 14 h oferece rendimentos que tendem à maior produtividade. Assim, as melhores condições para a obtenção de concentrados foram: maior relação de uréia/AG (6:1), menor temperatura (-12ºC) e menor tempo (14 h). Sendo que nestas condições as frações líquidas apresentaram rendimento em massa de até 65,4%, e seu percentual de ácidos graxos livres (%AGL) ficou em média 35,8 g/100g ácido oléico. Os ácidos graxos mono e poliinsaturados na melhor condição de complexação com uréia foram concentrados em 85,2%, e entre estes os EPA+DHA foram concentrados em 9,4%.

Efeito da Gália como aditivo de sinterização em eletrólitos cerâmicos à base de céria sintetizados pelo método de complexação de cátions

Fuel cells are considered one of the most promising ways of converting electrical energy due to its high yield and by using hydrogen (as fuel) which is considered one of the most important source of clean energy for the future. Rare earths doped ceria has been widely investigated as an alternative material for the electrolyte of solid oxide fuel cells (SOFCs) due to its high ionic conductivity at low operating temperatures compared with the traditional electrolytes based on stabilized zirconia. This work investigates the effect of gallium oxide (Gallia) as a sintering aid in Eu doped ceria ceramic electrolytes since this effect has already been investigated for Gd, Sm and Y doped ceria electrolytes. The desired goal with the use of a sintering aid is to reduce the sintering temperature aiming to produce dense ceramics. In this study we investigated the effects on densification, microstructure and ionic conduction caused by different molar fraction of the dopants europium (10, 15 and 20%) and gallium oxide (0.3, 0.6 and 0.9%) in samples sintered at 1300, 1350 and 1450 0 C. Samaria (10 and 20%) doped ceria samples sintered between 1350 and 1450 °C were used as reference. Samples were synthesized using the cation complexation method. The ceramics powders were characterized by XRF, XRD and SEM, while the sintered samples were investigated by its relative density, SEM and impedance spectroscopy. It was showed that gallia contents up to 0.6% act as excellent sintering aids in Eu doped ceria. Above this aid content, gallia addition does not promote significant increase in density of the ceramics. In Ga free samples the larger densification were accomplished with Eu 15% molar, effect expressed in the microstructure with higher grain growth although reduced and surrounded by many open pores. Relative densities greater than 95 % were obtained by sintering between 1300 and 1350 °C against the usual range 1500 - 1600 0 C. Samples containing 10% of Sm and 0.9% of Ga reached 96% of theoretical density by sintering at 1350 0 C for 3h, a gain compared to 97% achieved with 20% of Sm and 1% of Ga co-doped cerias sintered at 1450 0 C for 24 h as described in the literature. It is found that the addition of gallia in the Eu doped ceria has a positive effect on the grain conductivity and a negative one in the grain boundary conductivity resulting in a small decrease in the total conductivity which will not compromise its application as sintering aids in ceria based electrolytes. Typical total conductivity values at 600 and 700 °C, around 10 and 30 mS.cm -1 respectively were reached in this study. Samples with 15% of Eu and 0.9 % of Ga sintered at 1300 and 1350 °C showed relative densities greater than 96% and total conductivity (measured at 700 °C) between 20 and 33 mS.cm -1 . The simultaneous sintering of the electrolyte with the anode is one of the goals of research in materials for SOFCs. The results obtained in this study suggest that dense Eu and Ga co-doped ceria electrolytes with good ionic conductivity can be sintered simultaneously with the anode at temperatures below 1350 °C, the usual temperature for firing porous anode materials

Síntese e caracterização de tungstatos de cério e estrôncio para fins catalíticos

The main goal of this work was to produce nanosized ceramic materials of the family of the tungstates (tungstates of cerium and strontium), and test them for their catalytic activity in processes involving the transformation of methane (CH4). The methodology used for the synthesis of the ceramic powders involved the complexation combining EDTA-citrate. The materials characterization was performed using simple and differential thermogravimetry, x-ray diffraction, transmission electron microscopy, and energy dispersive spectroscopy (EDS). The microstructure analysis was performed using the refinement by the Rietveld method, and the crystallite size and distribution of the materials was elucidate by the Scherrer and Williamson-Hall methods. The conditions of the synthesis process for the three envisaged materials (SrWO4, SrWO4 using tungsten oxide concentrate as raw material, and Ce2(WO4)3) were adjusted to obtain a single phase crystalline material. The catalytic tests were carried out in the presence of methane and synthetic air, which is composed of 21% O2 and 79% N2. The analysis of the conversion of the reaction was done with the aid of an fourier transform infrared device (FTIR). The analysis showed that, structurally, the SrWO4 produced using raw materials of high and poor purity (99% and 92%, respectively) are similar. The ideal parameters of calcination, in the tested range, are temperature of 1000 °C and time of calcination 5 hours. For the Ce2(WO4)3, the ideal calcination time and are temperature 15 hours and 1000°C, respectively. The Williamson-Hall method provided two different distributions for the crystallite size of each material, whose values ranged between the nanometer and micrometer scales. According to method of Scherrer, all materials produced were composed of nanometric crystallites. The analyses of transmission electron microscopy confirmed the results obtained from the Williamson- Hall method for the crystallite size. The EDS showed an atomic composition for the metals in the SrWO4 that was different of the theoretical composition. With respect to the catalytic tests, all materials were found to be catalytically active, but the reaction process should be further studied and optimized.

Desenvolvimento de uma rota química alternativa de síntese de SrCo0,8Fe0,2O3- e LaNi0,3Co0,7O3- para aplicação na reação de oxidação do CO

This thesis focuses on the coprecipitation synthesis method for preparation of ceramic materials with perovskite structure, their characterization and application as catalytic material in the reaction of converting CO to CO2 developing a methodological alternative route of synthesis from the middle via oxalate coprecipitation material SrCo0,8Fe0,2O3-d. In order to check the influence of this method, it was also synthesized using a combined citrate - EDTA complexing method. The material was characterized by: X-ray diffraction (XRD), Rietveld refinement method, thermogravimetry and differential thermo analysis (TG / DTA), scanning (SEM) and transmission (TEM) electron microscopy, particle size distribution and surface analysis method BET. Both methods led to post-phase synthesis, with pH as a relevant parameter. The synthesis based on the method via oxalate coprecipitation among particles led to the crystalline phase as those obtained using a combined citrate - EDTA complexing method under the same conditions of heat treatment. The nature of the reagent used via oxalate coprecipitation method produced a material with approximately 80 % lower than the average size of crystallites. Moreover, the via oxalate coprecipitation method precursors obtained in the solid state at low temperature (~ 26 oC), shorter synthesis, greater thermal stability and a higher yield of around 90-95 %, maintaining the same order of magnitude the crystallite size that the combined citrate - EDTA complexing method. For purposes of comparing the catalytic properties of the material was also synthesized by the using a combined citrate - EDTA complexing method. The evaluation of catalytic materials SrCo0,8Fe0,2O3-d LaNi0,3Co0,7O3-d was accompanied on the oxidation of CO to CO2 using a stainless steel tubular reactor in the temperature range of 75-300 oC. The conversion CO gas was evaluated in both materials on the results shaved that the firm conversion was loves for the material LaNi0,3Co0,7O3-d

Desenvolvimento e caracterização de nanopartículas poliméricas com propriedades mucoadesivas para administração oral de zidovudina

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento de material BaCexPr1-xO3 (0 ≤ X ≤ 1) com estrutura perovskita para oxidação catalítica do CO a CO2 em reator de leito fixo

Barium Cerate (BaCeO3) is perovskite type structure of ABO3, wherein A and B are metal cations. These materials, or doped, have been studied by having characteristics that make them promising for the application in fuel cells solid oxide, hydrogen and oxygen permeation, as catalysts, etc .. However, as the ceramic materials mixed conductivity have been produced by different synthesis methods, some conditions directly influence the final properties, one of the most important doping Site B, which may have direct influence on the crystallite size, which in turn directly influences their catalytic activity. In this study, perovskite-type (BaCexO3) had cerium gradually replaced by praseodymium to obtain ternary type materials BaCexPr1-xO3 and BaPrO3 binaries. These materials were synthesized by EDTA/Citrate complexing method and the material characterized via XRD, SEM and BET for the identification of their structure, morphology and surface area. Moreover were performed on all materials, catalytic test in a fixed bed reactor for the identification of that person responsible for complete conversion of CO to CO2 at low operating temperature, which step can be used as the subsequent production of synthesis gas (CO + H2) from methane oxidation. In the present work the crystalline phase having the orthorhombic structure was obtained for all compositions, with a morphology consisting of agglomerated particles being more pronounced with increasing praseodymium in the crystal structure. The average crystal size was between 100 nm and 142,2 nm. The surface areas were 2,62 m²g-1 for the BaCeO3 composition, 3,03 m²g-1 to BaCe0,5Pr0,5O3 composition and 2,37 m²g-1 to BaPrO3 composition. Regarding the catalytic tests, we can conclude that the optimal flow reactor operation was 50 ml / min and the composition regarding the maximum rate of conversion to the lowest temperature was BaCeO3 to 400° C. Meanwhile, there was found that the partially replaced by praseodymium, cerium, there was a decrease in the catalytic activity of the material.

Development of Locust Bean Gum Nanoparticles for protein delivery

Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2014

Desenvolvimento de quelantes macrocíclicos para complexação de iões metálicos de transição e lantanídeos com interesse em aplicações médicas

A investigação de novos compostos macrocíclicos tetraaza tem sido intensificada ao longo das últimas décadas, uma vez que estes estão entre os melhores ligandos para complexação de iões metálicos. Desta forma, tanto a síntese destes compostos, como as propriedades dos seus complexos com iões metálicos provocaram o seu crescente interesse em variadíssimas áreas, das quais são exemplo a medicina, a biologia, a catálise, e a química analítica. Procuram-se ligandos específicos para determinados iões metálicos, mas que ao mesmo tempo se preparem por processos de síntese simples e eficazes que permitam uma maior utilização ao nível industrial. Com este trabalho procurou-se dar continuidade aos estudos desenvolvidos nesta área desde 1980 pelo grupo de investigação onde me encontro inserida e assim obter ligandos novos com vista à formação de complexos com iões metálicos estáveis e aplicáveis ao nível da medicina e da farmacologia, com destaque para as aplicações relacionadas com o diagnóstico e a terapia de tumores. Assim, foram sintetizados quatro novos ligandos derivados de macrociclos tetraaza com 12 átomos no anel, dois deles com ponte cruzada curta tipo etano. A síntes baseou-se na funcionalização destes macrociclos com braços pendentes metilnitrofenol ou metilfenol, originando assim os seguintes compostos: cb-do2nph, do2nph, cb-do2ph e do do2ph. Todos os compostos sintetizados foram caracterizados por diversas técnicas analíticas. Os compostos cb-do2nph e do2nph mostraram reduzida solubilidade em água e em metanol:água, pelo que não foi possível a determinação de constantes por potenciometria. Preparam-se alguns complexos que se estudaram em solução por espectroscopia electrónica e no estado sólido por difracção de raios X. O composto do2ph só se obteve em pequena quantidade sem revelar a pureza necessária e, a sua síntese ainda terá de ser optimizada. Finalmente, o composto cb-do2ph foi sintetizado em quantidade suficiente para se poderem determinar as suas constantes de protonação e as constantes de estabilidade dos seus complexos com Cu 2+ e Zn 2+, pelo método potenciomátrico, em solução aquosa, à temperatura de 298,2 K e à força iónica 0,10M em N(CH 3)4NO3. Determinaram-se ainda por potenciometria as constantes de protonação bem como as constantes de estabilidade dos complexos com Mg2+, Cu2+, Zn 2+, Fe3+, Ga3+, In3+, Gd3+, do composto cbdbf-do2a, igualmente em solução aquosa, à temperatura de 298,2K e à força iónica 0,10M em N(CH 3)4NO3. Para ambos os compostos, cb-do2ph e cbdbf-do2a, recorreu-se a titulações por espectroscopia de RMN de 1H para a determinação da primeira constante, por esta ter um valor muito elevado (log K1 ≥ 14), ou seja, estes compostos comportaram-se como “esponjas de protão”. Para obter informações estruturais dos complexos de alguns ligandos com cobre (II) realizaram-se estudos por espectroscopia de absorção de UV-Vis e de RPE, tendo-se ainda obtido cristais de tamanho suficiente para a determinação de estruturas por difracção de raios X de alguns compostos e complexos de cobre (II) e Zinco(II).

Síntese e caracterização de pós Ba(x)Sr(1-x)Co0,8Fe0,2O3- através do método de coprecipitação via oxalato

Ceramic powders based on oxides of perovskite-type structure is of fundamental interest nowadays, since they have important ionic-electronic conductivity in the use of materials with technological applications such as gas sensors, oxygen permeation membranes, catalysts and electrolytes for solid oxide fuel cells (SOFC). The main objective of the project is to develop nanostructured ceramic compounds quaternary-based oxide Barium (Br), Strontium (Sr), Cobalt (Co) and Iron (Fe). In this project were synthesized compounds BaxSr(1-x)Co0, 8Fe0,2O3- (x = 0.2, 0.5 and 0.8) through the oxalate co-precipitation method. The synthesized powders were characterized by thermogravimetric analysis and differential thermal analysis (TGADTA), X-ray diffraction (XRD) with the Rietveld refinement using the software MAUD and scanning electron microscopy (SEM). The results showed that the synthesis technique used was suitable for production of nanostructured ceramic solid solutions. The powders obtained had a crystalline phase with perovskite-type structure. The TGA-DTA results showed that the homogeneous phase of interest was obtained temperature above 1034°C. It was also observed that the heating rate of the calcination process did not affect the elimination of impurities present in the ceramic powder. The variation in the addition of barium dopant promoted changes in the average crystallite size in the nanometer range, the composition being BSCF(5582) obtained the lowest value (179.0nm). The results obtained by oxalate co-precipitation method were compared with those synthesis methods in solid state and EDTA-citrate method

Complexação de guaiacol com ß-ciclodextrina para tratamento de alveolite seca: avaliação in vitro e in vivo

A alveolite seca (AS) é uma das complicações pós-operatórias mais comuns e sintomáticas na odontologia, porém, até o momento não há um protocolo de tratamento definido. O composto fenólico guaiacol (Gu) é um dos materiais utilizados para revestimento intra-alveolar devido às suas propriedades analgésicas, antioxidantes e antimicrobianas. Contudo, sua desvantagem é a dificuldade de manipulação decorrente da sua baixa estabilidade, alta volatilidade e sensibilidade à oxidação. Para melhorar suas propriedades e aumentar sua aplicabilidade clínica, um complexo de inclusão de Gu com ß-ciclodextrina (ßcd) foi desenvolvido. A formação do complexo supramolecular de Gu:ßcd foi caracterizada mediante a ressonância magnética nuclear (RMN), nos experimentos de 1H e 2D ROESY. A atividade antibacteriana do Gu e Gu:ßcd frente a Escherichia coli, Staphylococcus aureus, Streptococcus mitis, Streptococcus mutans, Streptococcus sanguis e Aggregatibacter actinomycetemcomitans foi analisada pelo método da microdiluição e sua citotoxicidade em osteoblastos de calvária de rato, foi estudado com o ensaio do MTT. O processo de reparo alveolar induzido pelo Gu:ßcd foi avaliado histologicamente após tratamento de alveolite seca em molares inferiores de ratos. A RMN mostrou correlações espaciais entre os hidrogênios internos (H3 e H5) da ßcd e os hidrogênios aromáticos, H(a) e H(b) do Gu, confirmando a formação do complexo. A complexação do Gu na ßcd potencializou seu efeito antibacteriano e reduziu sua citotoxicidade em osteoblastos. O estudo in vivo evidenciou a ocorrência de ossificação no ápice alveolar dos ratos tratados com Gu:ßcd, no 7o dia. No 14o dia, as trabéculas ósseas ocuparam também o terço médio do alvéolo e no 21o dia, todo o alvéolo se encontrava preenchido por osso neoformado. Estes resultados foram similares ao controle negativo e superiores ao controle positivo (Alvogyl®). Os benefícios obtidos pela inclusão do Gu na ßcd foram demonstrados pela melhora das propriedades biológicas do Gu in vitro e o adequado reparo alveolar in vivo.

Desenvolvimento de método para determinação de ferro e cobre em vinho por espectrofotometria empregando DLLME

Este trabalho propõe o desenvolvimento de métodos de preparo de amostra empregando a microextração líquido-líquido dispersiva (DLLME) para a extração e pré- concentração de Fe e Cu em vinho, seguido da determinação espectrofotométrica na região do ultravioleta-visível (UV-Vis). Nas extrações por DLLME, a complexação de Fe e Cu foi feita com pirrolidina ditiocarbamato de amônio (APDC) e dietilditiocarbamato de sódio (DDTC), respectivamente. Para a DLLME, foi usada uma mistura apropriada de pequenos volumes de dois solventes, um extrator e outro dispersor, a qual foi rapidamente injetada na amostra aquosa, ocorrendo à formação de uma dispersão e a extração praticamente instantânea dos analitos. Na otimização da DLLME para extração de Fe foram avaliados alguns parâmetros como, tipo de solvente extrator (C2Cl4, 80 µL) e dispersor (acetonitrila, 1300 µL) e seus volumes, pH (3,0), concentração do APDC (1%, m/v), adição de NaCl (0,02 mol L -1 ) e tempo de extração. Para extração de Cu foi aplicado um planejamento fatorial completo 25 para avaliar a influência de cinco variáveis independentes: volume dos solventes dispersor (acetonitrila, 1600 µL) e extrator (CCl4, 60 µL), concentração de DDTC (2%, m/v), pH (3,0) e concentração de NaCl. Após a otimização das condições para Fe, a curva de calibração com adição de analito foi linear entre 0,2 e 2,5 mg L-1 para vinho branco (R2 = 0,9985) e para vinho tinto (R2 = 0,9988). Para Cu, a curva de calibração com adição de analito foi linear entre 0,05 e 1,0 mg L-1 para vinho branco (R2 = 0,9995) e para vinho tinto (R2 = 0,9986). Os limites de quantificação foram de 0,75 e 0,37 mg L-1 para Fe e Cu, respectivamente. A exatidão foi avaliada utilizando ensaio de recuperação, as quais variaram entre 96% e 112%, com desvio padrão relativo inferior a 8%. Os métodos foram aplicados para 5 amostras de vinho branco e 5 amostras de vinho tinto, obtendo-se concentrações entre 1,3 e 5,3 e entre 2,5 e 4,4 mg L-1 para Fe e entre 0,4 e 1,5 e entre 0,9 e 2,5 mg L-1 para Cu, respectivamente. Os métodos desenvolvidos para a extração e pré-concentração de Fe e Cu em vinhos por DLLME e quantificação por UV-Vis mostraram-se adequados, em termos de linearidade, exatidão e precisão.

Aspectos técnicos da monitorização da pressão intracraniana pelo método subaracnóideo no traumatismo craniencefálico grave

Two hundred and six patients with severe head injury (Glasgow Coma Scale of 8 points or less after nonsurgical resuscitation on admission), managed at Intensive Care Unit-Hospital das Clínicas - Universidade Estadual de Campinas were prospectively analysed. All patients were assessed by CT scan and 72 required neurosurgical intervention. All patients were continuously monitored to evaluate intracranial pressure (ICP) levels by a subarachnoid device (11 with subarachnoid metallic bolts and 195 with subarachnoid polyvinyl catheters). The ICP levels were continuously observed in the bedside pressure monitor display and their end-hour values were recorded in a standard chart. The patients were managed according to a standard protocol guided by the ICP levels. There were no intracranial haemorrhagic complications or hematomas due the monitoring method. Sixty six patients were punctured by lateral C1-C2 technique to assess infectious complications and 2 had positive cerebrospinal fluid samples for Acinetobacter sp. The final results measured at hospital discharge showed 75 deaths (36,40%) and 131 (63,60%) survivors. ICP levels had significantly influenced the final results (p<0,001). The subarachnoid method to continuously assess the ICP levels was considered aplicable, safe, simple, low cost and useful to advise the management of the patients. The ICP record methodology was practical and useful. Despite the current technical advances the subarachnoid method was considered viable to assess the ICP levels in severe head injury.