Made available in DSpace on 2014-12-17T14:16:34Z (GMT). No. of bitstreams: 1 DaianeSS_DISSERT.pdf: 2054024 bytes, checksum: bee46a4b535270b61e0c79e3911040aa (MD5) Previous issue date: 2013-05-22 / Clays are natural materials that have great potential for use as excipients for solid dosage forms. Palygorskite is a type of clay that has hydrophilic properties as well as a large surface area, which could contribute to the dissolution of drugs. Thus, the present study aims to evaluate the use of palygorskite clay, from Piaui (Northeast region of Brazil), as a pharmaceutical excipient for solid dosage forms, using rifampicin and isoniazid as the model drugs. The former is a poorly soluble drug often associated with isoniazid for tuberculosis treatment. Palygorskite was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and specific surface area (BET). The rheological and technological properties of palygorskite were determined and compared to those of talc, magnesium stearate and Aersosil 200. Mixtures between drugs and palygorskite were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) combined with thermal analysis (DTA) and Fourier Transform Infrared Spectroscopy (FT-IR), where the results were compared with those of the individual compounds. In addition, dissolution studies of solid dispersions and capsules containing the drugs, mixed with either palygorskite or a mixture of talc and magnesium stearate, were performed. The results showed that palygorskite has small particles with a high surface area. Its rheological characteristics were better than those of others commonly used glidants and lubricants. There was no interaction between palygorskite and the drugs (rifampicin and isoniazid). Among the dispersions studied, the mixture with palygorskite (5%) showed the highest drug dissolution when compared to other excipients. The dissolution of the rifampicin capsules containing palygosrkite was faster in higher concentrations. However, these differences were statistically different only in the first minutes of the dissolution experiment. The dissolution profile of isoniazid was also statistically different on the initial part of the experiment. The formulations prepared with isoniazid and palygorskite showed higher drug dissolution, but it was in descending order of concentration. According to these results, the palygorskite clay used in this study has great potential for application as an excipient for solid dosage forms / Argilas s?o materiais naturais, com baixa toxicidade e com potencial para atuar como excipiente. A atapulgita ? uma argila com caracter?stica hidrof?lica e grande ?rea superficial. Assim, este trabalho tem por objetivo avaliar o uso da atapulgita como excipiente farmac?utico em formas s?lidas, utilizando a rifampicina e a isoniazida como f?rmacos-modelo. A atapulgita ? proveniente do Estado do Piau?, Nordeste, Brasil. A rifampicina ? um f?rmaco de baixa solubilidade frequentemente associado ? isoniazida para o tratamento da tuberculose. Inicialmente a atapulgita foi caracterizada por difra??o de raios-X (DRX), fluoresc?ncia de raios-X (FRX), an?lise granulom?trica, microscopia eletr?nica de transmiss?o (MET) e varredura (MEV) e determina??o da ?rea de superf?cie espec?fica (BET). As propriedades reol?gicas e tecnol?gicas da argila foram determinadas e comparadas ao talco, estearato de magn?sio e Aerosil 200. Misturas entre os f?rmacos e a argila (1:1, 1:2 e 1:1:1), bem como os materiais isolados, foram avaliadas por calorimetria explorat?ria diferencial (DSC), an?lise termogravim?trica (TG) combinada ? an?lise t?rmica diferencial (DTA) e espectroscopia na regi?o do infravermelho com transformada de Fourier (FT- IR). Estudos de dissolu??o de dispers?es s?lidas e de c?psulas contendo os f?rmacos e a atapulgita foram realizados e comparados ao emprego de talco e estearato de magn?sio. Os resultados mostraram que a atapulgita apresenta part?culas pequenas, com grande ?rea de superf?cie. Apresentou boas caracter?sticas reol?gicas quando comparada ao demais reguladores de fluxo. N?o foi evidenciada intera??o com os f?rmacos testados. Entre as dispers?es, as misturas com atapulgita (5%) mostraram maior dissolu??o dos f?rmacos em rela??o a outros excipientes . O perfil de dissolu??o da rifampicina foi superior na formula??o de c?psula contendo atapulgita em maior concentra??o, sendo estatisticamente diferente nos primeiros minutos. O perfil de dissolu??o da isoniazida tamb?m se mostrou estatisticamente diferente nos primeiros minutos, sendo as formula??es com atapulgita as que apresentaram maior dissolu??o do f?rmaco, por?m em ordem decrescente de concentra??o. A argila atapulgita apresenta, portanto, potencial para aplica??o como excipiente em formas farmac?uticas s?lidas

Made available in DSpace on 2014-12-17T14:57:41Z (GMT). No. of bitstreams: 1 JoseFTJ.pdf: 1695651 bytes, checksum: 0a95ed624ef6e5342ad90e1b6193878e (MD5) Previous issue date: 2007-12-17 / This a study on the achievement of alumina membranes by the method of anodizing. From this method got up a layer of aluminum oxide on the anodic metal, who presented the basic properties necessary for the application as a support for the production and acquisition of nanomaterials, such as porosity nano and resistance to high temperature, and other properties, as resistance to corrosion, and chemical, high ranking of the structure and pore size of the pores. The latter, ranging from 10 to 100nm depended on the electrolyte used, which in this study was the H2SO4. To remove all remaining aluminum, it is a bath of dissolution with HCl and CuCl where the residual aluminum has been withdrawn, and the deep pores were opened after chemical treatment with NaOH. After the dissolution, the membranes were calcined at temperatures of 300, 600 and 900? C, and sintered at temperatures of 1200 and 1300? C to win mechanical strength, porosity and observe the desired crystallization. Then went through analyses of composition through X-ray diffraction and morphology of the microstructure through a scanning electron microscope. The method was effective for obtaining alumine membranes applied in the processes of production of materials in nano / Trata de um estudo sobre a obten??o de membranas de alumina atrav?s do m?todo da anodiza??o. A partir deste m?todo obteve-se uma camada de ?xido an?dico sobre o alum?nio met?lico, que apresentou as propriedades b?sicas necess?rias ? aplica??o como suporte para produ??o e obten??o de nanomateriais, tais como: porosidade nanom?trica e resist?ncia a altas temperaturas, al?m de outras propriedades, como resist?ncia ? corros?o, e qu?mica, alta ordena??o da estrutura dos poros e tamanho dos poros. Este ?ltimo, variando de 10 at? 100nm dependeu do eletr?lito usado, o qual neste estudo foi o H2SO4. Para retirar todo alum?nio restante, procedeu-se um banho de dissolu??o com HCl e CuCl no qual o alum?nio residual foi retirado, e os poros profundos foram abertos ap?s o tratamento qu?mico com NaOH. Ap?s a dissolu??o, as membranas foram calcinadas nas temperaturas de 300, 600 e 900? C, e sinterizadas nas temperaturas de 1200 e 1300? C para ganhar resist?ncia mec?nica, porosidade desejada e observar a cristaliza??o. Em seguida passou por an?lises de composi??o atrav?s da Difra??o de Raios-X e morfologia da microestrutura por meio de um microsc?pio eletr?nico de varredura. O m?todo se mostrou eficiente para obten??o de membranas de alumina aplicadas nos processos de produ??o de materiais em escala nanom?trica

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2016-10-05T18:21:53Z No. of bitstreams: 1 2016 - Jo?o Pedro Chalfun Haouche Meneses.pdf: 6719960 bytes, checksum: ac9a27b5731b19e4693f71fae09adefe (MD5) / Made available in DSpace on 2016-10-05T18:21:53Z (GMT). No. of bitstreams: 1 2016 - Jo?o Pedro Chalfun Haouche Meneses.pdf: 6719960 bytes, checksum: ac9a27b5731b19e4693f71fae09adefe (MD5) Previous issue date: 2016-01-25 / Petrobras / The drilling of wells in salt layers faces major challenges in Brazil?s oil industry. Drilling in such layers requires the development of new technologies and operational procedures to make the process economically viable. One of the main problems is the dissolution of the salt layers in water-based drilling fluids. An uncontrolled dissolution presents a potential risk for the operation and can cause abrupt changes in the properties of the fluids. The main objective of this work was to study the effects of the dissolution of sodium chloride particles in non-Newtonian fluids containing xanthan gum. The study was divided into three parts, rheological experiments, kinetics experiments in a mixing tank and a mathematical modeling. The rheological experiments aimed at studies of the effect of the addition of saline particles on the rheology of non-Newtonian fluids, the effect of the concentration of suspended particles in the rheology of saturated fluids and the effect of the size of suspended particles in the rheology of saturated fluids. The Einstein equation was used to calculate the apparent viscosity of saturated fluids, taking into account the effect of the concentration of salt particles in suspension. The experiments in the mixing tank aimed at the study of the kinetics of dissolution with time in different operating conditions. Fluids were prepared using different concentrations of xanthan gum and different initial concentrations of sodium chloride. The effects of the viscosifier concentration and the initial concentration gradient were evaluated. A phenomenological model was used to represent the dissolution process, which provides the variation of the concentration of the fluid, the variation of the volume fraction of solids, the variation of the particles mean diameter and the variation of the interfacial mass transfer area as a function of time. In the rheology studies, it was verified that the addition of sodium chloride to the non-Newtonian fluid, in the studied conditions, increased the apparent viscosity of the solution. The increase of the concentration of suspended sodium chloride particles increased the apparent viscosity of the suspensions. The increase of the size of the suspended particles decreased the apparent viscosity of the suspension. Statistical tests were made in order to evaluate the statistical relevance of the performed studies. In the kinetics study, the convective mass transfer coefficient was estimated and simulations were made for the other variables of the process. The estimations showed that the xanthan gum concentration in the fluid and the initial sodium chloride concentration in the fluid affect the mass transfer coefficient. The average relative error observed for the simulations was 2,2%. / A perfura??o de po?os em camadas salinas enfrenta grandes desafios na ind?stria de petr?leo do Brasil. A perfura??o em tais camadas exige o desenvolvimento de novas tecnologias e procedimentos operacionais para tornar a perfura??o economicamente vi?vel. Um dos principais problemas enfrentados ? a dissolu??o das camadas de sais em fluidos de perfura??o base ?gua. Uma dissolu??o descontrolada apresenta um risco em potencial para a opera??o, podendo causar mudan?as bruscas nas propriedades dos fluidos. Este trabalho teve como principal objetivo estudar os efeitos da dissolu??o de part?culas de cloreto de s?dio em fluidos n?o-Newtonianos contendo goma xantana. O estudo foi dividido em tr?s partes, experimentos reol?gicos, experimentos de cin?tica em um tanque de mistura e modelagem matem?tica. Os experimentos reol?gicos tiveram como objetivo os estudos do efeito da adi??o de part?culas salinas na reologia de fluidos n?o-Newtonianos, do efeito da concentra??o de part?culas suspensas na reologia de fluidos saturados e do efeito do tamanho das part?culas suspensas na reologia de fluidos saturados. A equa??o de Einstein foi utilizada para calcular a viscosidade aparente dos fluidos saturados levando em conta o efeito da concentra??o de part?culas salinas em suspens?o. Os experimentos no tanque de mistura tiveram como objetivo o estudo da cin?tica de dissolu??o com o tempo em diferentes condi??es operacionais. Foram preparados fluidos com diferentes concentra??es de goma xantana e diferentes concentra??es iniciais de cloreto de s?dio. Foi analisado o efeito da concentra??o do viscosificante na cin?tica de dissolu??o bem como o efeito do gradiente de concentra??o inicial. Um modelo fenomenol?gico foi utilizado para representar o processo de dissolu??o, o qual prev? as varia??es da concentra??o do fluido, a varia??o da fra??o volum?trica de s?lidos, a varia??o do di?metro m?dio das part?culas e a varia??o da ?rea interfacial de transfer?ncia de massa em fun??o do tempo. Nos estudos de reologia, verificou-se que a adi??o de cloreto de s?dio ao fluido n?o-Newtoniano, nas condi??es estudadas, aumentou a viscosidade aparente da solu??o. O aumento da concentra??o de part?culas suspensas de cloreto de s?dio provocou um aumento na viscosidade aparente das suspens?es. O aumento do tamanho das part?culas suspensas de cloreto de s?dio diminuiu a viscosidade aparente da suspens?o. Testes estat?sticos foram feitos para analisar a relev?ncia estat?stica dos estudos realizados. No estudo da cin?tica, o coeficiente convectivo de transfer?ncia de massa foi estimado e simula??es foram feitas para as demais vari?veis do processo. As estima??es mostraram que a concentra??o de goma xantana no fluido e a concentra??o inicial de cloreto de s?dio no fluido influenciam o coeficiente de transfer?ncia de massa. O erro relativo m?dio simula??es observado para as simula??es foi de 2,2%.

Made available in DSpace on 2014-12-17T15:42:01Z (GMT). No. of bitstreams: 1 EdissonMJ.pdf: 6565731 bytes, checksum: 5d6fdd6db6fc25a30c6100d96fff1edc (MD5) Previous issue date: 2007-08-24 / TiTanate NanoTubes (TTNT) were synthesized by hydrothermal alkali treatment of TiO2 anatase followed by repeated washings with distinct degrees of proton exchange. TTNT samples with different sodium contents were characterized, as synthesized and after heattreatment (200-800?C), by X-ray diffraction, scanning and transmission electron microscopy, electron diffraction, thermal analysis, nitrogen adsorption and spectroscopic techniques like FTIR and UV-Vis diffuse reflectance. It was demonstrated that TTNTs consist of trititanate structure with general formula NaxH2−xTi3O7?nH2O, retaining interlayer water in its multiwalled structure. The removal of sodium reduces the amount of water and contracts the interlayer space leading, combined with other factors, to increased specific surface area and mesopore volume. TTNTs are mesoporous materials with two main contributions: pores smaller than 10 nm due to the inner volume of nanotubes and larger pores within 5-60 nm attributed to the interparticles space. Chemical composition and crystal structure of TTNTs do not depend on the average crystal size of the precursor TiO2-anatase, but this parameter affects significantly the morphology and textural properties of the nanostructured product. Such dependence has been rationalized using a dissolution-recrystallization mechanism, which takes into account the dissolution rate of the starting anatase and its influence on the relative rates of growth and curving of intermediate nanosheets. The thermal stability of TTNT is defined by the sodium content and in a lower extent by the crystallinity of the starting anatase. It has been demonstrated that after losing interlayer water within the range 100-200?C, TTNT transforms, at least partially, into an intermediate hexatitanate NaxH2−xTi6O13 still retaining the nanotubular morphology. Further thermal transformation of the nanostructured tri- and hexatitanates occurs at higher or lower temperature and follows different routes depending on the sodium content in the structure. At high sodium load (water washed samples) they sinter and grow towards bigger crystals of Na2Ti3O7 and Na2Ti6O13 in the form of rods and ribbons. In contrast, protonated TTNTs evolve to nanotubes of TiO2(B), which easily convert to anatase nanorods above 400?C. Besides hydroxyls and Lewis acidity typical of titanium oxides, TTNTs show a small contribution of protonic acidity capable of coordinating with pyridine at 150?C, which is lost after calcination and conversion into anatase. The isoeletric point of TTNTs was measured within the range 2.5-4.0, indicating behavior of a weak acid. Despite displaying semiconductor characteristics exhibiting typical absorption in the UV-Vis spectrum with estimated bandgap energy slightly higher than that of its TiO2 precursor, TTNTs showed very low performance in the photocatalytic degradation of cationic and anionic dyes. It was concluded that the basic reason resides in its layered titanate structure, which in comparison with the TiO2 form would be more prone to the so undesired electron-hole pair recombination, thus inhibiting the photooxidation reactions. After calcination of the protonated TTNT into anatase nanorods, the photocatalytic activity improved but not to the same level as that exhibited by its precursor anatase / Titanatos nanoestruturados, particularmente TiTanatos NanoTubulares (TTNT), foram sintetizados por tratamento hidrot?rmico alcalino de TiO2-anat?sio seguido de repetidas lavagens com diversos graus de troca prot?nica. Amostras de TTNT com diferentes teores de s?dio foram caracterizadas na forma de p? seco e ap?s calcina??o (200-800?C) por difra??o de raios-X, microscopia eletr?nica de varredura e transmiss?o, difra??o de el?trons, an?lise t?rmica, adsor??o de nitrog?nio e t?cnicas espectrosc?picas de infravermelho e de reflet?ncia difusa no UV-Vis?vel. Demonstrou-se que tais materiais de paredes multilamelares s?o trititanatos de f?rmula geral NaxH2−xTi3O7?nH2O, retendo ?gua entre as lamelas. A remo??o de s?dio da estrutura reduz a quantidade de ?gua contraindo o espa?o interlamelar levando, combinado a outros fatores, ao aumento da ?rea e do volume de poros espec?ficos. Os TTNTs s?o materiais mesoporosos com duas contribui??es principais: poros menores que 10 nm devido ao volume interno dos nanotubos e poros entre 5 e 60 nm devido aos espa?os interpart?cula. A composi??o qu?mica e a estrutura cristalina do TTNT n?o dependem do tamanho de cristalito do TiO2-anat?sio precursor, todavia este par?metro afeta significativamente a morfologia e as caracter?sticas texturais do produto nanoestruturado. Tal depend?ncia foi racionalizada atrav?s de um mecanismo de dissolu??o-recristaliza??o que leva em conta a velocidade de dissolu??o do TiO2 de partida e sua influ?ncia sobre a taxa de crescimento de nanofolhas intermedi?rias em rela??o ? taxa de seu curvamento a nanotubos. A estabilidade t?rmica do TTNT ? definida pelo teor de s?dio e em pequena extens?o pelo tipo de anat?sio de partida. Foi demonstrado que o TTNT ap?s perder a ?gua intercalada entre 100 e 200?C se transforma pelo menos parcialmente num hexatitanato NaxH2−xTi6O13 intermedi?rio ainda nanotubular. A transforma??o t?rmica do tri- e hexatitanato nanoestruturados ocorre em maior ou menor temperatura e segue diferentes rotas dependendo do teor de s?dio. No caso de alto s?dio sinterizam e crescem at? grandes cristais de Na2Ti3O7 e Na2Ti6O13 na forma de bast?es e fitas acima de 600?C. No caso da amostra protonizada evoluem para nanotubos de TiO2(B) que facilmente se convertem em nanobast?es de anat?sio acima de 400?C. Al?m de hidroxilas e acidez de Lewis t?picos dos ?xidos de tit?nio, os TTNTs apresentam uma pequena contribui??o de acidez prot?nica capaz de se coordenar com a piridina a 150?C, e que ? perdida ap?s sua calcina??o e transforma??o ? anat?sio. O ponto isoel?trico do TTNT variou dentro da faixa 2,5- 4,0, indicando o comportamento de um ?cido fraco. Apesar de se revelar um semicondutor exibindo banda de absor??o t?pica no espectro de UV-vis?vel com energia de bandgap ligeiramente superior ao do respectivo TiO2-anat?sio precursor, os TTNTs apresentaram baixo desempenho fotocatal?tico na degrada??o de corantes cati?nico e ani?nico. Concluiu-se que a causa fundamental reside em sua estrutura de titanato lamelar que, em rela??o ? forma TiO2, apresentaria maior probabilidade de recombina??o do par el?tron-lacuna (e-/h+), inibindo as rea??es de fotoxida??o. A transforma??o do TTNT prot?nico ? nanobast?es de anat?sio melhorou a atividade fotocatal?tica, por?m ainda sem atingir o mesmo desempenho do TiO2-anat?sio precursor