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Investigation and Synthesis of Novel Graphene-Based Nanocomposites for Hydrogen StorageD'angelo, Anthony Joseph 01 January 2012 (has links)
It is of great interest to develop and utilize a high surface area material with optimized hydrogen sorption properties. The need for a renewable energy source to replace automobile gasoline has become more critical in the past decade. Hydrogen is a viable fuel source for automobile usage; however, the question of how hydrogen will be safely and efficiently stored still remains. Critical factors for optimum hydrogen storage include ambient conditions and low activation temperature for adsorption and desorption phenomena. In order for optimum hydrogen adsorption to be achieved, the properties of (1) high surface area, (2) optimum hydrogen adsorption energy, and (3) Kubas interactions between metals and hydrogen molecules need to be considered. Fullerenes have recently become more popular with the discovery and mass production of graphene sheets derived from graphite. Graphene is a modified form of graphite that takes the form of sheets with less agglomeration than its respective graphitic form. This form has the potential for high surface area and storage capabilities. Storage of hydrogen at room temperature must be optimized by increasing the surface area and having an adsorption enthalpy between 15 - 20 KJ/mol. Graphene (G) sheets and graphene oxide (GO) sheets have been utilized as a matrix for hydrogen storage. These materials can also be cross-linked with organic spacers in order to form a porous framework of higher surface area. Metal decorating by calcium and platinum of the G/GO matrix has been used to enhance Kubas interactions, adsorption enthalpies, and spillover phenomenon. The use of a polymer matrix has also been implemented. Polyaniline is a novel superconducting polymer with unique electronic properties. Complexes of Polyaniline with graphene and graphene oxide have been investigated for hydrogen storage properties. Graphene and graphene oxide surface modification via metal decoration have been investigated in order to determine the most efficient synthesis and particle size on the G/GO matrix. Characterization by XRD, BET, adsorption enthalpy, PCT, TGA, FT-IR, and TEM/SEM (when applicable) were employed to optimize and compare the materials in the effort to develop a suitable storage material.
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Obtencao de um sistema de liberacao controlada de drogas a partir do PVAL irradiado com radiacao gamaTERENCE, MAURO C. 09 October 2014 (has links)
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Estudo do efeito da radiacao sobre a poliamida-6 recicladaEVORA, MARIA C.C. 09 October 2014 (has links)
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Estudos da sintese por irradiacao, da estrutura e do mecanismo de formacao de polipropileno com alta resistencia do fundidoLUGAO, ADEMAR B. 09 October 2014 (has links)
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Estudo da caracterização de espumas de polietileno reticulado pelo processo de irradiação com feixe de elétronsDIAS, DJALMA B. 09 October 2014 (has links)
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Incorporacao e liberacao de resveratrol em hidrogeis polimericos / Resveratrol immobilization and release in polymeric hydrogelsMOMESSO, ROBERTA G.R.A.P. 09 October 2014 (has links)
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Estudo da estrutura e dos parametros de reticulacao de membranas hidrofilas a base de poli(N-vinil-2-pirrolidona) induzidas por radiacaoLOPERGOLO, LILIAN C. 09 October 2014 (has links)
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Estudo dos efeitos da radiação gama no polietileno linear de baixa densidade (PELBD) injetado / Study of effects gamma radiation linear low density polyetilene (LLDPE) injectedOLIVEIRA, ANA C.F. de 10 November 2014 (has links)
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Avaliação de aspectos e tecnológicos para obtenção de sistemas nanoestruturados polímeros para administração oral de insulinaBEZERRA, Janira Maria Nascimento Alves 15 March 2016 (has links)
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Previous issue date: 2016-03-15 / CNPq / O desenvolvimento de sistemas de administração de fármacos utilizando biopolímeros, como
a goma de cajueiro e quitosana tem-se destacado pela formação de nanoestruturas por
complexação polieletrolítica, realizada pela interação das diferentes cargas dos materiais e
devido as suas promissoras propriedades, dentre elas: excelente biodegradabilidade, elevada
biocompatibilidade, baixa toxicidade. Usados no desenvolvimento nanotecnológico de
formulações para proteção de fármacos peptídicos, como a insulina, para sua administração
por via oral, no qual faz-se necessário pela sua instabilidade em variações de pH. Este
trabalho teve como objetivo a síntese de nanopartículas a partir de biopolímeros por
complexação polieletrolítica para administração oral de insulina e avaliação analítica do
fármaco e seu principal produto de degradação o A-21 em meio ácido. Nanopartículas de
goma de cajueiro e quitosana foram sintetizadas por complexação polieletrolítica com e sem
adição do tripolifosfato de sódio, como agente de reticulação. Foram caracterizadas quanto ao
seu tamanho, carga superficial, índice de polidispersão e adicionalmente a Espectroscopia da
Região do Infravermelho (FTIR), Microscopia Eletrônica de Varredura (MEV), Análise
Termogravimétrica (TG). Para a determinação analítica da insulina e seu principal produto de
degradação o A-21 foi realizado um planejamento experimental fatorial, a fim de analisar
quais variantes iriam influenciar para obtenção de um menor tempo de análise das moléculas
por HPLC. Vinte e sete experimentos foram realizados e destacou-se dentre os valores
observados nos tempos de retenção de 5,18 min para insulina e 9,10 min para o A-21, na
condição onde a temperatura da coluna foi de 35°C, fluxo do eluente de 1,0 mL/min-1 e na
proporção da fase móvel de 52% KH2PO4, 31% acetonitrila e 17% metanol, uma análise final
com cerca de 11 minutos. Em média os fatores que mais influenciaram no sistema foram o
fluxo do eluente e a proporção da fase móvel, demonstrados através da estimativa dos efeito,
análise da variância e teste F. O modelo linear obtido demonstrou ter uma boa predição para o
método, com pontos reais de distribuição aleatórios condizentes aos resultados obtidos
experimentalmente, a variância total explicada de 91,14% e o modelo deixa de explicar
8,86% dos resíduos. A adequabilidade cromatográfica da combinação das variáveis
independentes resultaram em valores próximos ou dentro dos limites estabelecidos. Os
resultados das avaliações de concentração dos biopolímeros, proporção dos agentes de
reticulação, ordens de adição, pH das soluções mostraram-se bastante significativos na
influência dos tamanhos das partículas, potencial zeta e índice de polidispersão. Houve uma
grande distinção das preparações com e sem TPP, pois foi evidenciada uma eficaz ação
reticulante entre os polieletrólitos, as ligações cruzadas realizadas foram importantes para
aperfeiçoamento dos parâmetros, demonstrado a redução dos tamanhos das nanopartículas, de
modo homogêneo e com baixos índices de polidispersão, potenciais zeta na faixa neutra
diferindo nos valores de acordo com a concentração adicionado. Através das caracterizações
realizadas por FTIR, MEV e TG houve a demonstração da interação entre os materiais
estudados. As características e propriedades apresentadas pelas nanoesferas formadas pela
interação GC/TPP/QT indicam um promissor sistema de liberação de fármacos e proteção
para moléculas instáveis ao ambiente gastrointestinal. / The development of drug delivery systems using biopolymers such as cashew gum and
chitosan it has been highlighted by the formation of nanostructures by complexation
polyelectrolytic held by the interaction of the different loads of materials and due to their
promising properties, among them: excellent biodegradability , high biocompatibility, low
toxicity. Used in nanotechnological development of formulations for protection peptide drugs
such as insulin, for administration orally, in which it is necessary for its instability at pH
variations. This study aimed to the synthesis of nanoparticles from biopolymers by
complexation polyelectrolytic for oral administration of insulin and analytical evaluation of
the drug and its main degradation product A-21 in acid. cashew gum and chitosan
nanoparticles were synthesized by complexation polyelectrolytic with and without addition of
sodium tripolyphosphate as crosslinking agent. They were characterized as to their size,
surface charge, polydispersity and additionally Spectroscopy Infrared Region index (FTIR),
Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TG). For the analytical
determination of insulin and its main degradation product A-21 factorial experimental design
was conducted to analyze variants which would influence to obtain a shorter analysis of
molecules by HPLC. Twenty-seven experiments were conducted and it was highlighted
among the values observed at 5.18 min retention time of 9.10 min for insulin and A-21 in the
condition where the column temperature was 35 ° C, flow of the eluent of 1.0 ml / min-1 and
the rate of mobile phase of 52% KH2PO4, 31% acetonitrile and 17% methanol, with a final
analysis about 11 minutes. On average the factors that most influence the system were the
eluent flow and the proportion of the mobile phase, demonstrated by estimating the effect of
variance analysis and test F. The resulting linear model was shown to have a good prediction
for the method, with points real random distribution consistent with the results obtained
experimentally, the total explained variance of 91.14% and the model fails to explain 8.86%
of the waste. Chromatographic suitability of the combination of the independent variables
resulted in close to or within the established limits. The results of evaluations concentration of
biopolymers, the proportion of cross-linking agents, addition orders, the solutions pH were
quite significant in the influence of particle size, zeta potential and molecular weight
distribution index. There was distinction of preparations with and without TPP, as was
evidenced effective action crosslinking of polyelectrolytes, cross-connections made were
important for improvement of the parameters shown to reduce the size of the nanoparticles,
homogeneous way and with low levels of polydispersity, zeta potential in the neutral range in
differing values according to the concentration added. Through the characterizations made by
FTIR, SEM and TG was the demonstration of the interaction between the studied materials.
The characteristics and properties presented by the nanospheres formed by the interaction GC
/ TPP / QT indicate a promising system of drug delivery and protection for unstable
molecules to the gastrointestinal environment.
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Obtencao de um sistema de liberacao controlada de drogas a partir do PVAL irradiado com radiacao gamaTERENCE, MAURO C. 09 October 2014 (has links)
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