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LOBO, Marina Duarte Pinto. Caracterização bioquímica, biológica e estrutural de uma quitinase recombinante de chromobacterium violaceum. 2012. 155 f. Dissertação (Mestrado em Bioquímica)-Universidade Federal do Ceará, Fortaleza-CE, 2012. / Submitted by Eric Santiago (erichhcl@gmail.com) on 2016-06-20T13:15:13Z No. of bitstreams: 1 2012_dis_mdplobo.pdf: 6869513 bytes, checksum: 8d02e390f0ef45b4615dca68d8af1c3c (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-07-26T19:58:36Z (GMT) No. of bitstreams: 1 2012_dis_mdplobo.pdf: 6869513 bytes, checksum: 8d02e390f0ef45b4615dca68d8af1c3c (MD5) / Made available in DSpace on 2016-07-26T19:58:36Z (GMT). No. of bitstreams: 1 2012_dis_mdplobo.pdf: 6869513 bytes, checksum: 8d02e390f0ef45b4615dca68d8af1c3c (MD5) Previous issue date: 2012 / Chromobacterium violaceum is a Gram-negative, saprophytic, non-pathogenic and free living bacterium. The complete sequencing of its genome has revealed many genes encoding products of biotechnological interest. Among these products are several chitinases. Chitinases, enzymes capable of degrading chitin, an insoluble polymer of β(1,4)-linked N-acetyl-β-D-glucosamine (GlcNAc), are of great biotechnological interest, because they can be used to convert chitin in useful derivatives as well as being exploited for the control of fungi and insects that cause damages in crops. This study aimed to carry out the biochemical, biological and structural characterization of a recombinant chitinase, belonging to family GH18, from C. violaceum ATCC 12472. The ORF CV2935 was amplified by polymerase chain reaction (PCR) and cloned into the vectors pET303/CT-His and pPICZαA, for expression in Escherichia coli and Pichia pastoris, respectively. In both systems, the enzyme was secreted into the culture medium, in its soluble and functional form, and purified to homogeneity by affinity chromatography on a chitin matrix followed by size-exclusion chromatography on Superdex75 matrix. The yields of pure chitinase expressed in E. coli and P. pastoris were 2.6 and 44 mg per liter of culture, respectively. The recombinant chitinase produced in both microrganisms showed optimal activity at pH 3.0 and it was active after treated at temperatures up to 60 °C. The enzyme produced in P. pastoris (45 kDa) was N-glycosylated as revealed by Schiffʼs reagent and digestion with N-glycosidase F. Moreover, the glycosylated chitinase was found to be slightly more thermostable than the enzyme produced in E. coli (43 kDa). The rCV2935 showed hydrolytic activity against colloidal chitin, crab shell, and synthetic substrates containing p-nitrophenol. It was also able to hydrolyse glycol-chitin in SDS-PAGE and showed low chitosanase activity. The fluorescence spectra revealed that the proteins were produced in their folded conformation. The crystal structure of the recombinant chitinase produced in P. pastoris was determined by X-ray crystallography at a resolution of 2.1Ǻ. Its catalytic domain adopts an (β/α)8 triose-phosohate isomerase (TIM) barrel fold, and the residues essential for catalysis are conserved. The recombinant chitinase reduced the growth of the phytopathogenic fungus Rhizoctonia solani, and bioassays with cowpea weevil Callosobruchus maculatus showed that the rCV2935 possibly interfered with the insect feeding, which resulted in decreased weight of adults. The biochemical, biological and structural studies of rCV2935 may be useful for biotechnological application of this enzyme. / Chromobacterium violaceum é uma bactéria Gram-negativa, saprófita, não patogênica e de vida livre. O seqüenciamento completo do genoma dessa espécie revelou muitos genes codificando produtos com potenciais aplicações em diversas áreas. Dentre esses produtos, estão várias quitinases. Quitinases, enzimas capazes de degradar a quitina, um biopolímero de N-acetil-β-D-glucosamina bastante insolúvel, são de grande interesse biotecnológico, podendo ser utilizadas para converter quitina em derivados úteis, e também para o controle de fungos e insetos que causam danos em culturas agrícolas. O presente trabalho teve como objetivo caracterizar bioquímica, biológica e estruturalmente uma quitinase recombinante (CV2935), da família 18 das glicosídeo hidrolases, de C. violaceum ATCC 12472. A ORF codificando a proteína CV2935 foi amplificada por reação em cadeia da polimerase (PCR) e clonada nos vetores pET303/CT-His e pPICZαA, para expressão em Escherichia coli e Pichia pastoris, respectivamente. Em ambos os sistemas, a enzima foi secretada para o meio de cultura, na sua forma solúvel e funcional, sendo purificada a homogeneidade por cromatografia de afinidade em matriz de quitina, seguida de cromatografia de exclusão molecular em matriz de Superdex75. Os rendimentos da quitinase pura, expressa em E. coli e P. pastoris, foram 2,6 e 44 mg por litro de cultura, respectivamente. A quitinase produzida em ambos os microorganismos mostrou atividade ótima em pH 3,0 e foi ativa quando tratada a temperaturas de até 60 °C. A enzima produzida em P. pastoris (45 kDa) foi N-glicosilada, como revelado por coramento com reagente de Schiff e digestão com N-glicosidase F, mostrando-se ligeiramente mais termoestável do que a enzima não glicosilada, produzida em E. coli (43 kDa). A rCV2935 apresentou atividade hidrolítica (endoquitinásica) frente a quitina coloidal, matriz de carapaça de caranguejo obtida comercialmente, glicol-quitina (em gel SDS-PAGE), substratos sintéticos solúveis contendo p-nitrofenol, além de apresentar pequena atividade quitosanásica. Os espectros de fluorescência revelaram que as proteínas foram produzidas na sua conformação enovelada. A enzima teve sua estrutura cristalográfica resolvida a uma resolução de 2.1Å e seu domínio catalítico apresentou um dobramento do tipo barril (β/α)8 (barril TIM) e resíduos essenciais para catálise conservados, características essas, comuns às proteínas da mesma família. A quitinase recombinante retardou o crescimento do fungo fitopatogênico Rhizoctonia solani, e, em bioensaios com o caruncho Callosobruchus maculatus, a rCV2935 possivelmente interferiu com a alimentação do inseto, o que acarretou na diminuição do peso dos mesmos. Os estudos bioquímicos, biológicos e estruturais da rCV2935 poderão ser úteis para aplicação biotecnológica dessa enzima.

Ferrierite is a high silica zeolite, with bidimensional microporous structure, that shows remarkable performance as acid catalyst in some reactions involving hydrocarbons, especially the isomerization of n-butene to isobutene. In most cases, ferrierite synthesis requires the use of organic structure-directing agents, which increases the material production cost and, consequently, hinders its application on an industrial scale. In the present work, a synthesis route to ferrierite zeolite without using any organic structure agent was developed, starting from a reaction mixture containing seed crystals. The samples were synthesized by hydrothermal method at the temperature of 170 ºC, employing the following reagents: pseudoboehmite, sodium hydroxide, potassium hydroxide and commercial silica. Seeds were prepared from a commercial ferrierite sample with high crystallinity. The synthesis parameters evaluated were as follows: percentage of seeds (5 and 15%), water content (300 and 500 mol) and synthesis time (12 to 72 h). The samples obtained were characterized by X-ray diffraction (XRD), absorption spectroscopy in the infrared region (FT-IR), thermal analysis (TG/DTA) and scanning electron microscopy (SEM). XRD results showed that ferrierite with good crystallinity can be synthesized in a period of 12 h, using a percentage of seeds of 15%, which proves the effectiveness of the proposed methodology. The water content did not affect significantly the crystallization time of ferrierite. However, the more diluted system delayed the advent of contaminating phases such as mordenite. The samples submitted for analysis by infrared spectroscopy showed absorption bands typical of zeolitic structures. Thermal analysis results showed a mass loss of 11 to 14% in the temperature range between 30 and 500 ºC, mainly attributed to the material dehydration. Scanning electron microscopy revealed that the ferrierite produced has an irregular morphology, due to the intergrowth of crystals. / A ferrierita é uma zeólita de alta sílica, com estrutura microporosa bidimensional, que apresenta notável desempenho como catalisador ácido em algumas reações envolvendo hidrocarbonetos, com destaque para a isomerização do n-buteno em isobuteno. Na maioria dos casos, a síntese da ferrierita exige a utilização de agentes orgânicos direcionadores de estrutura, o que aumenta o custo de produção do material e, consequentemente, dificulta sua aplicação em escala industrial. No presente trabalho foi desenvolvida uma rota de síntese da zeólita ferrierita sem o uso de direcionador orgânico, partindo de uma mistura reacional contendo sementes de cristalização. As amostras foram sintetizadas pelo método hidrotérmico à temperatura de 170 ºC, empregando os seguintes reagentes: pseudobohemita, hidróxido de sódio, hidróxido de potássio e sílica comercial. As sementes foram preparadas a partir de uma amostra de ferrierita comercial com alta cristalinidade. Os parâmetros de síntese avaliados foram o percentual de sementes (5 e 15%), o teor de água do sistema reacional (300 e 500 mol) e o tempo de síntese (12 a 72 h). As amostras obtidas foram caracterizadas por difratometria de raios X (DRX), espectroscopia de absorção na região do infravermelho (FT-IR), análises térmicas (TG/DTA) e microscopia eletrônica de varredura (MEV). Os resultados de DRX demonstraram que ferrierita com boa cristalinidade pode ser sintetizada em um período de 12 h, empregando um percentual de sementes de 15%, o que comprova a eficácia da metodologia proposta. O teor de água não influenciou de maneira significativa o tempo de cristalização da ferrierita. No entanto, o sistema mais diluído retardou o surgimento de fases contaminantes, como a mordenita. As amostras submetidas à análise por espectroscopia de infravermelho apresentaram as bandas de absorção típicas das estruturas zeolíticas. Os resultados das análises térmicas mostraram uma perda de massa de 11 a 14% na faixa de temperatura entre 30 e 500 ºC, atribuída principalmente à desidratação do material. A microscopia eletrônica de varredura revelou que a ferrierita produzida possui morfologia irregular, devido ao intercrescimento dos cristais.

Crystallization is a key unit operation used for obtaining purified products by many process industries. The key properties of the crystalline products, such as size and shape distribution, purity and polymorphic form are controlled by the crystallization process. All these properties impact significantly the downstream operations such as drying or filtration. Therefore, monitoring and controlling this process is fundamental to ensure the quality of the final product. Process analytical technology (PAT) brings numerous new methods and opportunities in the process analytics and real time process monitoring systems, which can be integrated into the control algorithm and provide high level optimal control strategies as well as deeper understanding of the process. Process monitoring helps develop mathematical models which can, in one hand, help in better understanding the processes and consecvently the development and application of advanced control methods in order to achieve better product quality. In this work, image processing and image analysis based direct nucleation control (IA-DNC) is developed in order to investigate the evolution of the crystal properties, such as crystal size, and crystal shape distribution. The IA-DNC approach is also compared to alternative DNC techniques, in which particle number were measured by Focused Beam Reflectance Measurement (FBRM) in order to control crystal size. A control approach is introduced that control the nucleation and disappearance of crystals during cooling and heating segments related to the changes of the number of counts (measured by Particle Vision Measurment, so called PVM or combination of FBRM and PVM). The approach was applied to investigate crystallization of compounds with different behavior: potassium dihydrogen phosphate (KDP) water, contaminated KDP -water and Ascorbic acid water systems. The results demonstrate the application of imaging technique for model-free feedback control for tailoring crystal product properties. The second main aim of the thesis is to investigate and control crystallization processes in impure media in the presence of multiple impurities, with an impact on the crystal shape via growth kinetics. The broad impact of the crystal growth modifiers (impurities) on the growth kinetics is observed in real time by using in situ video imaging probe and real-time image analysis. A morphological population balance model is developed, which incorporates a multi-site, competitive adsorption mechanism of the impurities on the crystal faces. The kinetic parameters of primary nucleation, growth and impurity adsorption for a model system of potassium dihydrogen phosphate crystallization in water in the presence of two impurities, were estimated and validated with experimental results. It was demonstrated that the model can be used to describe the dynamic evolution of crystal properties, such as size and aspect ratio during crystallization for different impurity profiles in the system. Manual, feedback and hybrid feedback-feedforward control techniques are developed and investigated numerically for continuous processes, while model-based and model-free control approach for crystal shape are developed for batch processes. The developed morphological population balance model is implemented and applied in the model-based control approaches, which are suitable to describe multicomponent adsorption processes and their influence on the crystal shape. Case studies show the effectiveness of crystal growth modifiers based shape control techniques. Comparison of different control approaches shows the effectiveness of the techniques. The third part of the thesis deals with purification of crystals when adsorption of impurities on crystal surfaces and its incorporation into crystals are considered. A purification method, called competitive purity control (CPC) is proposed and investigated. A morphological population balance model, including nucleation, growth and competitive impurity adsorption kinetics is developed to describe the case when multiple impurities can adsorb competitively on the crystal surface. The model is also combined with liquid phase chemical reaction model, in order to investigate the purity control case when an additive is introduced in the system that reacts with the impurity forming a non-adsorbing reaction product. Both competitive purity control approaches proposed: the adsorption based competitive purity control (A-CPC) and the reaction based competitive purity control (R-CPC); are investigated using detailed numerical simulations then compared with the alternative widely used purification method, called recrystallization. In the last contribution chapter, an integrated process optimization of a continuous chemical reactor and crystallizer is performed and studied numerically. The purpose of this study is to show the way in which the byproduct produced in the chemical reactor may affect the crystallization process and how its negative effect can be reduced by applying integrated process optimization. Sensitivity analysis of the system was performed by considering the flow rate and the concentration of substances in the input stream of the chemical reactor as manipulated process variables. Model based integrated process optimization and the sensitivity analysis in order to obtain improved quality product in terms of crystal size, shape and purity.

Le développement de systèmes d’assainissement spécifiques et décentralisés peut apporter des réponses à une double problématique : l’amélioration des conditions sanitaires dans les zones les plus pauvres du monde et le développement de sources renouvelables de nutriments essentiels pour l’agriculture. L’objectif de cette thèse est de développer des connaissances scientifiques sur une filière de traitement et valorisation de l’urine couplant une cristallisation à une séparation membranaire. Il a été démontré que la précipitation de phosphore sous forme de struvite permet de récupérer la quasi-totalité du phosphore et une partie de l’azote en 20 secondes environ suite à l’ajout de magnésium avec un ratio Mg :P=1,3 :1. L’influence des conditions d’agitation, de l’apport en magnésium, des conditions de stockage de l’urine et de la présence de matières organiques et de cristaux initiaux a été étudié en réacteur batch et continu.L’ultrafiltration de différents types d’urine (fraichement excrétée, stockée, stockée puis cristallisée) a été réalisée avec des membranes en PES, PAN et PVDF. Les mécanismes responsables de cette chute de flux ainsi que l’influence spécifique des fractions particulaires colloïdales et particulaires ont été étudiés. En se basant sur ces résultats différents procédés ont été proposés et discutés / The development of decentralized and specific sanitation system is an issue that concerns both the improvement of sanitary conditions in the poorest area of the world and the development of renewable sources of nutrients for agriculture. This study aims to provide some elements about a treatment line including crystallization and membrane separation for the treatment and valorization of urine. Crystallization allows to recover phosphorus and part of nitrogen contained in urine. Membrane separation is used in order to remove bacteria and viruses from urine. To check the potentialities of these processes some tests were performed at labscale with synthetic and real human urines.It was shown that the struvite crystallization by magnesium addition with a ratio Mg:P=1,3:1 allows recovering most of the phosphorus from urine with a very rapid kinetics (about 20s). Influence of mixing conditions, urine storage, organic matter and initial crystals in urine was studied in batch and continuous reactor. Ultrafiltrations of different pretreated urines (no pretreatment, stored urine, stored and crystallized urine) were performed with PES, PAN and PVDF membranes. Mechanisms responsible for an important flux decline during urine flitration were studied. Specific influence of particular, colloidal and soluble fraction on the flux decline was also evidenced. On these basis different possible treatment lines of urines are proposed and discussed

L’évaporation d’une solution saline en milieu poreux intervient dans diverses situations comme lors de l’injection de dioxyde de carbone dans des aquifères salins ou dans des processus de dégradation des monuments ou de la végétation. Un aspect clé est la cristallisation des sels dissous à la surface ou au sein du milieu poreux résultant de l’évaporation de la solution. Dans la première partie de ce manuscrit, nous étudions le séchage d’un milieu poreux modèle initialement saturé par une solution aqueuse de chlorure de sodium pour différentes tailles moyennes de pores et différents flux d’évaporation. Ceci nous permet d’obtenir une caractérisation des cristaux formés en surface (efflorescence) en fonction de ces paramètres. Nous nous intéressons ensuite tout particulièrement au cas où l’efflorescence forme une croûte d’apparence compacte. Un aspect intrigant est que cette croûte ne bloque pas complètement l’évaporation. Le taux d’évaporation est réduit d’un ordre de grandeur environ. Une modélisation de la croissance de la croûte est développée pour expliquer ce phénomène. Dans une deuxième partie du manuscrit, nous nous intéressons au phénomène relié à la croissance d’un efflorescence “rampante” à la surface d’un substrat solide, dans notre cas la surface externe d’un tube capillaire droit dont une extrémité est plongée dans une solution de chlorure de sodium. Les lois de croissance de ce phénomène sont caractérisées à partir du suivi temporel par double pesée de la masse d’eau évaporée et de la masse de sel qui précipite ainsi que de la géométrie de l’enveloppe externe de la couche de sel recouvrant progressivement le capillaire. Ici encore, l’analyse du phénomène de croissance est confortée par une modélisation numérique simple. Un aspect important de ce travail est le recours à des techniques de visualisations modernes (microtomographie à rayons X, microscopie électronique à balayage, scanner de surface à lumière structurée) pour obtenir autant d’informations que possible sur la structure des efflorescences et les mécanismes de croissance mis en jeu dans ces expériences. / Evaporation of saline solution in porous media occurs in various situations such as injection of carbon dioxide in saline aquifers or in degradation processes on monuments or on vegetation. A key aspect is the crystallization of dissolved salts on the surface or in the porous medium resulting from the evaporation of the solution. In the first part of this manuscript, we study the drying of model porous media model initially saturated with an aqueous solution of sodium chloride, for different average pore sizes and different evaporation fluxes. This allows us to obtain a characterization of the salt crystals formed on the surface (efflorescence) depending on these parameters. We are particularly interested in the case when the efflorescence forms an apparently compact crust. An intriguing aspect is that the crust does not completely block the evaporation. The evaporation rate is in fact reduced by an order of ten. To explain this phenomenon, a model of the growth of the crust is developed. In a second part of the manuscript, we are interested in the growth of a salt efflorescence by “creeping” on a solid substrate, here the outer surface of a straight capillary tube, with one end immersed in a sodium chloride solution. The growth laws of this phenomenon are characterized by weighing both the mass of water evaporated and the mass of salt that precipitates, as well as recording the geometry of the outer casing of the salt layer gradually covering the capillary. Again, the analysis of this growth phenomenon is supported by a simple numerical model. An important aspect of this work is the use of up-todate visuablisation techniques (such as X-ray micro-tomography, scanning electron microscopy and structuredlight surface scanning) to get as much as possible additional information on the efflorescence structure and growth mechanism at play in these experiments.

Les pièges froids sont des systèmes de purification du fluide caloporteur sodium indispensables au bon fonctionnement des réacteurs à neutrons rapides. Ils permettent de contrôler la teneur en impuretés du sodium, notamment celles de l’oxygène et de l’hydrogène. Le piégeage de ces impuretés est basé sur leur cristallisation sous forme d’oxyde et d’hydrure de sodium, sur garnissage et sur parois froides. Appréhender le remplissage de ces systèmes de purification permettra d’orienter les choix technologiques en termes de conception et de conduite. L’objectif est de développer un outil d’aide à la conception et à la simulation des pièges froids. Le modèle de cristallisation intègre le couplage des différents phénomènes mis en jeu lors de la purification du sodium, à savoir l’hydrodynamique, transfert thermique et transfert de matière. / Operating a Sodium Fast Reactor (SFR) in reliable and safe conditions requires to master the quality of the sodium fluid coolant, regarding oxygen and hydrogen impurities contents. A cold trap is a purification unit in SFR, designed for maintaining oxygen and hydrogen contents within acceptable limits. The purification of these impurities is based on crystallization of sodium hydride on cold walls and sodium oxide or hydride on wire mesh packing. Indeed, as oxygen and hydrogen solubilities are nearly nil at temperatures close to the sodium fusion point, i.e. 97.8°C, on line sodium purification can be performed by crystallization of sodium oxide and hydride from liquid sodium flows. However, the management of cold trap performances is necessary to prevent from unforeseen maintenance operations, which could induce shut-down of the reactor. It is thus essential to understand how a cold trap fills up with impurities crystallization in order to optimize the design of this system and to overcome any problems during nominal operation. The objective is to develop a design and simulation tool for cold traps able to predict the location and the amount of the impurities deposited. Crystallization model involve phenomena coupling in a porous medium with hydrodynamics, heat and mass transfer, distinguishing nucleation and growth phases for each impurity. It enables to understand how thermo hydraulic conditions and growing impurities interact on each other. This analysis will adapt operating and management conditions in order to optimize purification requirements.

Este trabalho investigou a influência do TiO2 em diferentes concentrações pelo processo convencional e sol-gel in situ. Essa avaliação foi baseada no efeito do TiO2 na cinéticas de formação do TiO2 a partir do precursor tetrabutóxido de titânio Ti(OBu)4, análises térmicas de degradação e cristalização, microscopia óptica de luz polarizada, morfologias, grau de cristalinidade por difração de raios-X, fotocalorimetria, comportamento viscoelástico, visando novos métodos e aplicações na indústria. Na cinética de conversão ficou evidenciado que para 10 min e 250°C o rendimento da reação foi maior. Na cinética de degradação o nanocompósito de PP/TiO2b1,5 demonstrou ter a maior estabilidade térmica. O ajuste linear a partir do modelo de FWO permitiu calcular a energia de ativação para entender o mecanismo de degradação e o método foi satisfatório onde os valores de α demonstraram um R2 de aproximadamente 0,998. A energia de ativação apresentou variações por causa da dispersão das nanopartículas e diferentes mecanismos de degradação. Para os dois sistemas estudados a adição das nanopartículas aumentaram a temperatura de cristalização e grau de cristalinidade pelo efeito nucleante. A nucleação e o crescimento dos cristais também foram afetados, como apontados no DSC e MOLP. Pode ser demonstrado por TEM que o nanocompósito de PP/TiO2b1,5 pode dispersar melhor a nanocarga quando comparado aos outros nanocompósitos. Na MOLP ficou evidenciado que a presença de TiO2 provocou a formação de mais sítios de nucleação e um crescimento heterogêneo de cristais quando comparado ao PP puro. Tanto o PP puro quanto os nanocompósitos obtidos pelos dois sistemas apresentaram os mesmos picos nos mesmos 2θ identificando então, os mesmos planos cristalinos, sem mudança no polimorfismo, mas heterogeneidade no tamanho dos cristais foi identificada. O aumento da rigidez nos nanocompósitos foi mais pronunciado acima de 100°C e na Tg houve uma queda para o sistema sol-gel in situ quando comparado ao PP puro. Com a adição de TiO2 os nanocompósitos para os dois sistemas apresentaram maior fluxo de calor com incidência da radiação UV sendo mais significativo para o nanocompósito de PP/TiO2b2,5 pelo TiO2 apresentar maior difusividade térmica em relação ao PP. / This work aimed to investigate the influence of TiO2 in several concentrations by conventional and sol-gel in situ process. This evaluation was based on the formation kinetics of TiO2 from titanium tetrabutoxide (Ti(OBu)4) precursor, degradation and crystallization thermal analysis, polarized optical light microscopy, transmission electronic morphology and degree of crystallinity by X-ray diffraction, photocalorimetry, viscoelastic behavior, looking for new methods and applications in industry. In the conversion kinetics was shown that for 10 min and 250°C, the reaction yield was higher. In the degradation kinetics of the nanocomposite of PP/TiO2b1,5 proved to have the highest thermal stability. The linear fit from FWO model allowed us to calculate the activation energy to understand the degradation mechanism and the method was satisfactory where the values of α showed R2 of approximately 0,998. The activation energy was varied because of the dispersion of nanoparticles and different degradation mechanisms. For the two systems studied the addition of nanoparticles increased the crystallization temperature and degree of crystallinity by nucleating effect. The nucleation and crystal growth were also affected, as indicated in the DSC and MOLP. It can be shown by TEM that the nanocomposite of PP/TiO2b1,5 could disperse better when compared to other nanocomposites. In MOLP evidenced that the presence of TiO2 caused the formation of more nucleation sites and heterogeneous crystal growth when compared to pure PP. Both the pure PP and nanocomposite obtained by two systems showed the same peaks at 2θ with the same crystal planes, without changing the polymorphism, but heterogeneity in size of the crystals was identified. The increased stiffness in the nanocomposites was more pronounced above 100°C and there was a decrease in the Tg for the sol-gel in situ system when compared to pure PP. With the addition of TiO2 the nanocomposites for both systems had higher heat flux to UV radiation incidence being more significant for the nanocomposite of PP/TiO2b2,5 by TiO2 present at greater thermal diffusivity compared to PP.

Made available in DSpace on 2014-06-11T19:25:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-27Bitstream added on 2014-06-13T19:32:46Z : No. of bitstreams: 1 costa_fb_me_ilha.pdf: 9510999 bytes, checksum: 9a5d3acde99bb0f41fcb579520ce6a76 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os vidros preparados para diversas aplicações têm um ponto em comum: a possibilidade de nuclear e cristalizar novas fases, quando preparados a partir de uma massa fundida ou através de um tratamento térmico acima da temperatura de transição vítrea. Neste trabalho são apresentadas de forma sucinta as formulações teóricas de formação de vidros incidindo principalmente nos processos de nucleação e crescimento de fases. O estudo da cristalização de vidros pode ser feito através de métodos cinéticos baseados na descrição teórica formulada por Johnson-Mehl- Avrami (JMA). Estes métodos descrevem os processos de nucleação e cristalização utilizando dados provenientes das curvas de DTA/DSC. Uma delas é aquela proposta por Kurajica, que determina os parâmetros cinéticos utilizando um modelo para a resolução da sobreposição dos picos de cristalização. Para a aplicação deste modelo, foram utilizados vidros teluretos, de composição 80TeO2 - 10Nb2O5 - 8Li2O - 2V2O5 (mol%) denominados TNLV, e vidros fosfatos, de composição 50P2O5 - 36Na2O - 10CdO - 4La2O3 (mol%), dopados com 20 e 60mg de CeO2 denominados PNCL20 e PNCL60. O estudo cinético teve início com a identificação das fases cristalinas formadas, utilizando a difratometria de raios X (DRX). Considerando a formação de três fases cristalinas para cada sistema vítreo, a equação proposta por Kurajica foi aplicada, utilizando o software Origin 7.0, para determinação dos parâmetros cinéticos, a partir dos ajustes dos dados de DSC. Os coeficientes de Avrami (n) determinados mostraram que para o sistema TNLV o crescimento se dá em três dimensões com mecanismos diferentes, enquanto que para os sistemas PNCL20 e PNCL60, o crescimento ocorre em três dimensões com reação de interface. Foi observado que... / The glasses prepared for various applications have one common point: the possibility of new phases nucleation and crystallization, when prepared from a melt or through a heat treatment above the glass transition temperature. In this work are presented briefly the theoretical formulations of formation of glass focusing mainly in the processes of phases nucleation and growth. The study of glass crystallization can be done by kinetic methods based on the theoretical description formulated by Johnson- Mehl-Avrami (JMA). These methods describe the processes of nucleation and crystallization using data from DTA/DSC curves. One model is that proposed by Kurajica which determine the kinetic parameters resolving overlapping peaks of crystallization. To apply this model were used a tellurite glass, with composition 80TeO2 - 10Nb2O5 - 8Li2O - 2V2O5 (mol%) denominated TNLV, and two phosphate glasses of composition 50P2O5 - 36Na2O - 10CdO - 4La2O3 (mol%) doped with 20 and 60mg of CeO2 denominated PNCL20 and PNCL60. The kinetic study started us with the identification of crystalline phase, using the X-ray diffraction (XRD). Considering that three crystalline phases are formed for each glassy system, the Kurajica equation was applied using the Origin 7.0 software, for determining the kinetic parameters. The calculated Avrami coefficients (n) shown that for the TNLV system the growth occurs in three dimensions with different mechanisms, while for the PNCL20 and PNCL60 systems the growth occurs in three dimensions with an interface reaction. It was observed that the PNCL20 system has higher activation energy that the PNCL60 system and XRD patterns showed that the characteristic peaks of the phases containing CeO2, become higher and thinner in the system PNCL60. These results show that the cerium may favors the glass crystallization.

La maîtrise et le contrôle de la cristallisation afin d’obtenir des cristaux de taille, de forme et du polymorphisme désirés reste une exigence de l’industrie pharmaceutique. La présence d’anti-solvant dans le milieu de cristallisation modifie les grandeurs fondamentales et les mécanismes de cette opération unitaire et peut être un outil permettant son contrôle. L’éthanol est l’un des anti-solvants qu’on peut utiliser dans la cristallisation de la glycine.Ce travail porte sur la cristallisation discontinue de la glycine dans des mélanges (eau/éthanol) par un procédé de cristallisation par refroidissement direct, ou par un procédé de cristallisation semi-continue isotherme de cette molécule en réalisant la sursaturation par ajout d’éthanol. On a étudié l’effet de la quantité et du débit d’éthanol sur différentes grandeurs fondamentales et son influence sur les différents mécanismes de cristallisation de la glycine, ainsi que sur les formes polymorphiques obtenues. / Crystallization is widely used in pharmaceutical industry; however it is necessary to control size, shape and crystal polymorphism. Anti-solvent presence in crystallization media is known to influence these separation process mechanisms, magnitudes and polymorphism. Consequently, anti-solvent use can be a way for crystallization control. For example ethanol can be used on glycine crystallization. In this thesis, we study the glycine crystallisation process in aqueous solutions with anti-solvent. The process takes place in a batch cooling crystallizer and in an isotherm semi batch crystallizer. We check ethanol amount and ethanol addition rate effects on different crystallization magnitudes and mechanisms; we check also the effect on polymorphism.