The thesis presents detailed results of theoretical analyses based on extensive computer simulation studies with an aim to explore, quantify whenever possible, and understand structure and dynamics of polymers and proteins in several complex solvents. In order to make the Thesis coherent, we also study certain aspects of binary mixtures. Based on the phenomena studied, the thesis has been divided into four major parts: I. Dynamics of biological water: Distance dependent variation of dielectric constants in aqueous protein solutions II. Temperature dependent study of structural transformations in aqueous binary mixtures III. Conformation and dynamics of polymers in solution: Role of aqueous binary mixtures IV. Conformational change and unfolding dynamics of proteins: Role of sol-vent environment The above mentioned four parts have further been divided into thirteen chapters. In the following we provide a brief chapter-wise outline of the thesis. Part I consists of two chapters, where we focus on the study of dynamics of biological water and distance dependent variation of static and dynamic proper-ties (including dielectric constant) of water near different proteins. To start with, chapter 1 provides an introduction to the structure and dynamics of biological water. Here we discuss different experimental studies; including dielectric relaxation, NMR and salvation dynamics those explore the bimolecular hydration dynamics in great detail. We also discuss the wide range of computer simulation and theoretical studies that have been carried out to understand the dynamical behaviour of biological water. In chapter 2, we present our molecular dynamics simulation study to ex-plore the distance dependent static and dynamic behaviour of biological water near four different protein surfaces. Proteins are known to have large permanent dipole moments that can influence structure and dynamics of even distant water molecules. Therefore, distance dependence of polarization punctuation can provide important insight into the nature of biological water. We explore these aspects by studying aqueous solutions of four different proteins of different char-acteristics and varying sizes. We find that the calculated dielectric constants of the systems show a noticeable increment in all the cases compared to that of neat water. Total dipole moment auto time correlation function of water is found to be sensitive to the nature of the protein. We also define and calculate the effective dielectric constant of successive layers and find that the layer adjacent to protein always has significantly lower value (∼ 50). However, progressive layers exhibit successive increment of dielectric constant, finally reaching a value close to that of bulk 4–5 layers away. Theoretical analysis providing simple method for calculation of shellwise local dielectric constant and implication of these findings are elaborately discussed in this chapter. Part II deals with the temperature dependent study of aqueous DMSO and ethanol solutions and consists of three chapters. Chapter 3 provides a general introduction to the non-ideality (deviation from Raoult’s law) encountered in different binary mixtures. We discuss different theoretical models for treatment of binary mixtures. Finally we provide a systematic study about the non-ideality observed in aqueous binary mixtures. Here we discuss the anomalies observed in such systems and carry out a brief survey on the existing ideas of structural transformations associated with the solvation of a foreign molecule in water. In chapter 4, we discuss the results of temperature dependent study of struc-tural and dynamic properties of aqueous dimethyl sulfoxide (DMSO) mixture. It is now well-known that aqueous DMSO mixture exhibits signature of perco-lation driven structural aggregation at a mole fraction range xDMSO ≈ 0.15. We study the structural and dynamical change in this binary mixture below and above the percolation threshold along with decreasing temperature. Significant change in the molecular structure of DMSO as well as that of water is observed above the percolation threshold at a lower temperature, particularly at 200K. The structural arrangement of the DMSO molecules is found to be progressively more ordered with increasing DMSO concentration and decreasing temperature. On the other hand, water structure is found to be significantly deviated from tetrahedral arrangement in presence of DMSO clusters even at low temperature. The dynamics of water is also found to be considerably affected with increase of concentration and lowering of temperature. Similar phenomenon is observed for another amphiphilic molecule, ethanol, and has been discussed in chapter 5. Aqueous ethanol mixture is a widely studied solvent, both experimentally and using computer simulations. All the studies indicate several distinct salvation regimes. In recent molecular dynamics simulation studies, the reason for formation of micro-aggregates of ethanol is again attributed to percolation driven structural transformation. We carry out a temperature dependent study of water-ethanol binary mixture, particularly at low ethanol concentration to understand the molecular origin of such structural transformation. We find that the structural arrangement of ethanol as well as water molecules is similarly affected as that of DMSO with lowering of temperature. However, dynamics of water molecules in aqueous ethanol solution is found to be marginally affected, unlike the case of aqueous DMSO solution. We discuss the microscopic reason for such behaviour in a detailed manner. In Part III, we discuss the dynamics of linear polymer chains in different aqueous binary mixtures. Here we have three chapters. In chapter 6, we carry out a brief survey of the existing theories of polymers in solution. We discuss the quality of solvents depending on the preferred interactions between the polymer and the solvent or the polymer with its own. We also discuss the celebrated Flory-Huggins theory. We derive the expression of free energy of the Flory-Huggins theory in terms of the volume fraction of monomer and solvent molecules. In chapter 7, we discuss the results of our study of polymer dynamics in aqueous DMSO solution. We find that at a mole fraction 0.05 of DMSO (xDMSO ≈ 0.05) in aqueous solution, a linear polymer chain of intermediate length (n=30) adopts collapsed conformation as the most stable conformational state. The same chain exhibits an intermittent oscillation between the collapsed and the extended coiled conformations in neat water. Even when the mole fraction of DMSO in the bulk is 0.05, the concentration of the same in the first hydration layer around the polymer is found to be as large as 17 %. Formation of such hydrophobic environment around the hydrocarbon chain may be viewed as the reason for the collapsed conformation gaining additional stability. We find a second anomalous behaviour to emerge near xDMSO ≈ 0.15 that is attributed to the percolation driven structural aggregation of DMSO that lowers the relative concentration of the DMSO molecules in the hydration layer. In chapter 8, we carry out similar study of linear polymer chain in water– ethanol binary mixture. In this case also, we find a sudden collapse of the poly-merat xEtOH ≈ 0.05. Since ethanol molecules are known to form micro-aggregates in this concentration range, stability of collapsed state of polymer at this con-centration is anticipated to be correlated to this phenomenon. In fact, a purely hydrophobic polymer chain, in its collapsed form is anticipated to assist in the formation of spanning cluster comprised of hydrophobic ethyl groups at this concentration range thereby facilitating the percolation transition. We discuss these prospects in this chapter. Part IV deals with the solvent sensitivity to the conformational change and unfolding dynamics of protein. Part IV consists of five chapters. In chapter 9, we develop an understanding of protein folding and unfolding dynamics by discussing the fundamental theories developed in the last few decades. We also discuss the major role of solvents in stabilizing or destabilizing the native, ordered state. In chapter 10, we present a detailed study of unfolding of a small protein, chicken villin headpiece (HP36) in water-ethanol binary mixture, using molecular dynamics simulations. The prime objective of this work is to explore the sensitivity of protein dynamics towards increasing concentration of the cosolvent and unravel essential features of intermediates formed in the unfolding path-way. In water–ethanol binary mixtures, HP36 is found to unfold partially, under ambient conditions, that otherwise requires temperature as high as ∼ 600K to denature in pure aqueous solvent. The study unravels certain interesting aspects about the pathway of unfolding, guided by the formation of unique intermediates. Unfolding is initiated by the separation of hydrophoic core comprising three phenylalanine residues (Phe7, Phe11, Phe18). This separation initiates the melting of the helix2 of the protein. However, with an increase of cosolvent concentration different partially unfolded intermediates are found to be formed. We attribute the emergence of such partially unfolded states to the preferential solvation of hydrophobic residues by the ethyl groups of ethanol. We explore and subsequently quantify the detailed dynamics of unfolding in water-ethanol that appear to be more complex and sensitive to solvent composition. With an aim to develop a general understanding of the role of water–ethanol binary mixture in facilitating anomalous conformational dynamics of proteins, we carry out combined theoretical and experimental studies to explore detailed structural change of a larger protein, Myoglobin with increasing ethanol concentration. These studies are described in chapter 11. In agreement with our pre-vious observations, we identify in this case two well-defined structural regimes, one at xEtOH ≈ 0.05 and the other at xEtOH ≈ 0.25, characterized by formation of distinct partially folded conformations and separated by a unique partially unfolded intermediate state at xEtOH ≈ 0.15. We also find non-monotonic com-position dependence of (i) radius of gyration (ii) long range contact order (iii) residue specific solvent accessible surface area of tryptophan (iv) circular dichro-ism spectra and UV-absorption peaks. Multiple structural transformations, well-known in water-ethanol binary mixture, appear to have considerably stronger effects on the conformation and dynamics of protein Myoglobin. In chapter 12, we explore the free energy surface of unfolding pathway through umbrella sampling, for the small globular alpha-helical protein chicken-villin headpiece (HP36) in three different solvent conditions (water, xDMSO ≈ 0.15 and xDMSO ≈ 0.3). Recently established as a facilitator of helix melting, DMSO is found to be a good denaturant for HP36 and at a mole fraction of xDMSO ≈ 0.3, complete melting of the protein is ensured. The unfolding proceeds through initial separation or melting of the same aggregated hydrophobic core that com-prises three phenylalanine residues (Phe7, Phe11 and Phe18) accompanied by simultaneous melting of the helix2. Unfolding is found to be a multistage process involving crossing of three consecutive minima and two barriers at the initial stage. At a molecular level, Phe18 is observed to reorient itself towards other hy-drophobic grooves to stabilize the intermediate states. We identify the configuration of intermediates in all the solvent conditions which are found to be unique for the corresponding minima with similar structural arrangement. Consider-able softening of the barriers is observed with increasing DMSO concentration. Higher concentration of DMSO tunes the unfolding pathway by destabilizing the third minimum and stabilizing the second one, indicating the development of solvent modified, less rugged pathway. Chapter 13 provides a detailed microscopic mechanism of DMSO induced unfolding of HP36. We analyze the free energy contours of the protein HP36, obtained from molecular dynamics simulation in xDMSO ≈ 0.15 and xDMSO ≈ 0.3. The most probable intermediates obtained from the free energy contours are found to be similar to those obtained from umbrella sampling which again sup-ports the fact that the melting proceeds through formation of a series of unique intermediates. We characterize the preferential hydrophobic salvation of the hydrophobic core that drives the melting of secondary structure, by calculating time dependent radial distribution function and identifying the formation of strong orientation order between methyl groups of DMSO and phenyl alanine residues. Finally we employ Kramer’s rate equation to calculate the rate of bar-rier crossing that reveals significantly faster rate of unfolding with increasing DMSO concentration that is in agreement with simulation results. Whenever possible, we have discussed the scope of future work at the end of each chapter.

abstract: Image segmentation is of great importance and value in many applications. In computer vision, image segmentation is the tool and process of locating objects and boundaries within images. The segmentation result may provide more meaningful image data. Generally, there are two fundamental image segmentation algorithms: discontinuity and similarity. The idea behind discontinuity is locating the abrupt changes in intensity of images, as are often seen in edges or boundaries. Similarity subdivides an image into regions that fit the pre-defined criteria. The algorithm utilized in this thesis is the second category. This study addresses the problem of particle image segmentation by measuring the similarity between a sampled region and an adjacent region, based on Bhattacharyya distance and an image feature extraction technique that uses distribution of local binary patterns and pattern contrasts. A boundary smoothing process is developed to improve the accuracy of the segmentation. The novel particle image segmentation algorithm is tested using four different cases of particle image velocimetry (PIV) images. The obtained experimental results of segmentations provide partitioning of the objects within 10 percent error rate. Ground-truth segmentation data, which are manually segmented image from each case, are used to calculate the error rate of the segmentations. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2015

abstract: Clarinet multiphonics have become increasingly popular among composers since they were first introduced in the 1950s. However, it is a topic poorly understood by both performers and composers, which sometimes leads to the use of acoustically impossible multiphonics in compositions. Producing multiphonics requires precise manipulations of embouchure force, air pressure, and tongue position. These three factors are invisible to the naked eye during clarinet performance, leading to many conflicting theories about multiphonic production strategies, often based on subjective perception of the performer. This study attempts to observe the latter factor—tongue motion—during multiphonic production in situ using ultrasound. Additionally, a multiphonic catalog containing 604 dyad multiphonics was compiled as part of this study. The author hypothesized that nearly all, if not all, of the multiphonics can be produced using one of four primary production strategies. The four production strategies are: (A) lowering the back of the tongue while sustaining the upper note; (B) raising the back of the tongue while sustaining the upper note; (C) changing the tongue position to that of the lower note while sustaining the upper note; and (D) raising the root of the tongue (a sensation similar to constricting the throat) while sustaining the upper note. To distill production strategies into four primary categories, the author documented his perceived tongue motion over twenty repetitions of playing every multiphonic in the catalog. These perceptions were then confirmed or corrected through ultrasound investigation sessions after every five repetitions. The production strategies detailed in this study are only for finding the correct voicing to produce the multiphonics. The catalog compiled during this study is organized using two different organizational systems: the first uses the traditional method of organizing by pitch; the second uses a fingering-based system to facilitate the ease of finding multiphonics in question, since notated pitches of multiphonics often differ between sources. / Dissertation/Thesis / Doctoral Dissertation Music 2018

Made available in DSpace on 2014-06-11T19:22:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-08Bitstream added on 2014-06-13T18:49:26Z : No. of bitstreams: 1 guimaraes_ahf_me_guara.pdf: 2381225 bytes, checksum: 8019dfa6ffed11e95f9f5a24914be192 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Universidade Estadual Paulista (UNESP) / Plutão e Caronte, bem como os novos satélites do sistema, Nix e Hidra, são alvos de micrometeoritos, provavelmente originários do cinturão de Kuiper. Os resíduos destes impactos permaneceriam no sistema em órbitas ao redor de Plutão ou Caronte. Este estudo analisa, através de simulações numéricas, a estabilidade das regiões ao redor do sistema binário. Esta análise deu-se através de simulações numéricas para o problema restrito de três corpos. Foram numericamente integradas órbitas para partículas ao redor de Plutão, ao redor de Caronte e ao redor do baricentro do sistema. Dessas integrações numéricas foram geradas grades a x e, definindo-se regiões: de estabilidade, de escape e de colisão. A região estável ao redor de Plutão vai até aproximadamente 8200km, ao redor de Caronte se estende até 2900km e ao redor do baricentro do sistema binário, órbitas Tipo-P, a região estável inicia-se a partir de 49000km. Estes valores estão de acordo com a teoria de Holman e Wiegert (1999). As regiões de estabilidade de Plutão Caronte foram também amplamente estudadas através do uso da Superfície de Secção de Poincaré (SSP). Um conjunto de cerca de 230 SSP foi obtido. Foram gerados diagramas de Cjxx, Cj é o valor da Constante de Jacobi, derivados das SSP para a região interna aos corpos massivos do binário e externa a eles. Estes diagramas representam a síntese da análise da estabilidade por meio das SSP. Neles ficam determinadas as regiões estáveis às partículas no sistema. Cojuntos especiais de SSP foram gerados para análise das ressonâncias 1:6 e 1:4, pois estas, em especial, estariam relacionadas aos novos satélites. Verificou-se que estes satélites estão em regiões estáveis, mas não em ressonância de acordo com o dados até hoje conhecidos. / Pluto and Charon and the two new discovered satellites, named Hydra and Nix, are targets of micrometeorites which were probably originated from the Kuiper belt. A sample of particles can be generated from these collision and be trapped in orbit around Pluto or Charon. This work analyses, through numerical simulations, the stable regions around the binary system. This analysis took into account the Restricted Three Body Problem. From these numerical simulations diagrams of a x e were generated defining, stable, escape and unstable regions. Stable regions around Pluto (width about 8200km), around Charon (width about 2900km) and around the baricentre of the binary system (after a semi-major axis about 49000km) were obtained. These values are in good agreement with the work by Holman & Wiegert (1999). These stable regions were also analysed by using the technique of POincaré Surface of Section (PSS). A sample of about 230 PSS was obtained. In all these PSS chaotic and stable regions and also the resonance locations were identified. Diagrams of Cj x x, derived from the PSS, were obtained. They represent the synthesis of the stability region acquired from the PSS. A particular set of SSP was generated in order to analyse the evolution of 1:4 and 1:6 resonances. The new satellites, Hydra and Nix, are located in stable regions although, they are not in resonances with Charon, as can be seen in the grade a x e.

As limitações resultantes do avanço das tecnologias de integração, como o crescente aumento da densidade de potência, levando à necessidade de redução da frequência de operação dos circuitos somados à necessidade de redução do consumo energético, sejam por motivos ecológicos ou para melhor suprir dispositivos portáteis, trazem a necessidade de maior intervenção e personalização do hardware em relação às exigências do software. Em diversos níveis estas intervenções podem ser aplicadas, onde a granularidade pode variar desde elementos de processamento sendo completamente desativados até processadores tendo apenas unidades funcionais sendo desativadas, memórias cache reconfiguradas em tamanho e associatividade, etc. Entretanto, a reconfiguração do hardware deve atingir todas as etapas destes sistemas para que seja possível atingir redução satisfatória em termos de potência e consumo de energia. Além da integração acelerada de elementos de processamento em um mesmo circuito integrado, a crescente concentração de heterogêneas tarefas em um mesmo dispositivo, leva à integração de elementos de processamento também heterogêneos, e por consequência diferentes comportamentos variando de acordo com a aplicação. Para justificar esta reconfigurabilidade e heterogeneidade dos elementos de processamento este trabalho apresenta um estudo que possibilita a observação da execução de diferentes aplicações em elementos de processamento amplamente reconfiguráveis. Para que a reconfigurabilidade e heterogeneidade possam ser aplicáveis, foi inserida uma ferramenta capaz de manter a compatibilidade entre o elemento de processamento mestre e os elementos de processamento aceleradores reconfiguráveis disponíveis. Os experimentos apresentados baseiam-se na necessidade de manter a menor quantidade de silício ativa, acelerando o código fonte enquanto reduz-se o consumo de energia. Somada a redução de energia, a compatibilidade binária é levada em consideração buscando a manutenção da produtividade quando da utilização de sistemas heterogêneos reconfiguráveis. / The limitations resulting from the advancement of integration technologies, such as the increasing power density, leading to the need to reduce the operating frequency of the circuits added to the need to reduce energy consumption, whether for environmental reasons or to better serve mobile devices, bring the need for greater intervention and hardware customization to the demands of the software. To varying degrees these interventions can be applied where the granularity can range from processing elements being completely disabled until processors having only functional units being disabled, reset cache memories in size and associativity, etc. However, the reconfiguration of hardware should reach all stages of these systems so that you can achieve satisfactory reduction in power and energy consumption. In addition to the accelerated integration of processing elements on a single integrated circuit, the increasing concentration of heterogeneous tasks in a same device, also leads to the integration of heterogeneous processing elements, and therefore different behavior varies according to the application. To justify this reconfigurability and variety of processing elements this work presents a study that allows the observation of the implementation of different applications in widely reconfigurable processing elements. For reconfigurability and heterogeneity may be applicable, a tool to maintain compatibility between the master processing element and accelerators reconfigurable processing elements available was inserted. The experiments presented are based on the need to maintain the lowest amount of active silicon, accelerating the source code while reducing power consumption. Added to energy reduction, binary compatibility is taken into consideration seeking to maintain productivity when using reconfigurable heterogeneous systems.

Atualmente, a adição de uma nova função implementada em hardware em um processador não deve impor nenhuma mudança no conjunto de instruções (ISA – Instruction Set Architecture) suportado para atingir melhorias em seu desempenho. O objetivo é manter a compatibilidade retroativa e futura de programas já compilados. Todavia, este fato se torna, muitas vezes, um fator impeditivo para o aprimoramento ou desenvolvimento de uma nova arquitetura. Desta maneira, a utilização de mecanismos de Tradução Binária abre novas oportunidades aos projetistas, já que estes mecanismos permitem a execução de programas já compilados em arquiteturas que suportam conjuntos de instruções diferentes do previsto inicialmente. Assim, para eliminar o custo adicional apresentado por estes sistemas de tradução, será proposto um novo mecanismo de tradução binária dinâmico de dois níveis. Enquanto o primeiro nível é responsável pela tradução de facto das instruções do conjunto nativo para instruções de uma linguagem de máquina intermediária, o segundo nível otimiza estas instruções já traduzidas para serem executadas na arquitetura alvo. O sistema é totalmente flexível, pois pode suportar a tradução de conjuntos de instruções completamente diferentes; assim como a utilização de arquiteturas de hardware com as mais diversas características. Este trabalho apresenta o primeiro esforço nesta direção: um estudo de caso onde ocorre a tradução de código x86 para MIPS (linguagem intermediária), que será otimizado para ser executado em uma arquitetura que realiza reconfiguração dinâmica. Resta demonstrado que é possível manter a compatibilidade binária, com melhoria no desempenho em torno de 45% em média e consumo de energia semelhante ao da execução nativa. / In these days, every new added hardware feature must not change the underlying instruction set architecture (ISA), in order to avoid adaptation or recompilation of existing code. Therefore, Binary Translation (BT) opens new possibilities for designers, previously tied to a specific ISA and all its legacy hardware issues, since it allows the execution of already compiled applications on different architectures. To overcome the BT inherent performance penalty, we propose a new mechanism based on a dynamic two-level binary translation system. While the first level is responsible for the BT de facto to an intermediate machine language, the second level optimizes the already translated instructions to be executed on the target architecture. The system is totally flexible, supporting the porting of radically different ISAs and the employment of different target architectures. This work presents the first effort towards this direction: it translates code implemented in the x86 ISA to MIPS assembly (the intermediate language), which will be optimized by the target architecture: a dynamically reconfigurable architecture. In this work is showed that is possible to maintain binary compatibility with performance improvements on average 45% and similar energy consumption when compared to native execution.

As limitações resultantes do avanço das tecnologias de integração, como o crescente aumento da densidade de potência, levando à necessidade de redução da frequência de operação dos circuitos somados à necessidade de redução do consumo energético, sejam por motivos ecológicos ou para melhor suprir dispositivos portáteis, trazem a necessidade de maior intervenção e personalização do hardware em relação às exigências do software. Em diversos níveis estas intervenções podem ser aplicadas, onde a granularidade pode variar desde elementos de processamento sendo completamente desativados até processadores tendo apenas unidades funcionais sendo desativadas, memórias cache reconfiguradas em tamanho e associatividade, etc. Entretanto, a reconfiguração do hardware deve atingir todas as etapas destes sistemas para que seja possível atingir redução satisfatória em termos de potência e consumo de energia. Além da integração acelerada de elementos de processamento em um mesmo circuito integrado, a crescente concentração de heterogêneas tarefas em um mesmo dispositivo, leva à integração de elementos de processamento também heterogêneos, e por consequência diferentes comportamentos variando de acordo com a aplicação. Para justificar esta reconfigurabilidade e heterogeneidade dos elementos de processamento este trabalho apresenta um estudo que possibilita a observação da execução de diferentes aplicações em elementos de processamento amplamente reconfiguráveis. Para que a reconfigurabilidade e heterogeneidade possam ser aplicáveis, foi inserida uma ferramenta capaz de manter a compatibilidade entre o elemento de processamento mestre e os elementos de processamento aceleradores reconfiguráveis disponíveis. Os experimentos apresentados baseiam-se na necessidade de manter a menor quantidade de silício ativa, acelerando o código fonte enquanto reduz-se o consumo de energia. Somada a redução de energia, a compatibilidade binária é levada em consideração buscando a manutenção da produtividade quando da utilização de sistemas heterogêneos reconfiguráveis. / The limitations resulting from the advancement of integration technologies, such as the increasing power density, leading to the need to reduce the operating frequency of the circuits added to the need to reduce energy consumption, whether for environmental reasons or to better serve mobile devices, bring the need for greater intervention and hardware customization to the demands of the software. To varying degrees these interventions can be applied where the granularity can range from processing elements being completely disabled until processors having only functional units being disabled, reset cache memories in size and associativity, etc. However, the reconfiguration of hardware should reach all stages of these systems so that you can achieve satisfactory reduction in power and energy consumption. In addition to the accelerated integration of processing elements on a single integrated circuit, the increasing concentration of heterogeneous tasks in a same device, also leads to the integration of heterogeneous processing elements, and therefore different behavior varies according to the application. To justify this reconfigurability and variety of processing elements this work presents a study that allows the observation of the implementation of different applications in widely reconfigurable processing elements. For reconfigurability and heterogeneity may be applicable, a tool to maintain compatibility between the master processing element and accelerators reconfigurable processing elements available was inserted. The experiments presented are based on the need to maintain the lowest amount of active silicon, accelerating the source code while reducing power consumption. Added to energy reduction, binary compatibility is taken into consideration seeking to maintain productivity when using reconfigurable heterogeneous systems.

Orientador: Daniel Barrera-Arellano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-15T08:05:38Z (GMT). No. of bitstreams: 1 Ribeiro_MarileneDeMoriMorselli_M.pdf: 5112345 bytes, checksum: 0515b869d93054892980d08c8bb30fd9 (MD5) Previous issue date: 2010 / Resumo: A facilidade de obtenção de micropartículas lipídicas e a possibilidade de produção em escala industrial aumentam o interesse do mercado alimentício de processar este tipo de material. Contudo, estas micropartículas apresentam desvantagens com relação à baixa encapsulação e à expulsão de material de recheio durante a estocagem. Assim, a finalidade deste trabalho foi estudar o comportamento das microcápsulas lipídicas produzidas pelo processo spray chilling utilizando as seguintes misturas em diferentes proporções: ácidos esteárico (AE) e oléico (AO), óleo de soja totalmente hidrogenado (STH) e ácido oléico (AO), álcool cetoestearílico (ACE) e ácido oléico (AO) como materiais de parede (matriz), lecitina de soja como tensoativo e solução de glicose como recheio. O objetivo foi aumentar a eficiência de encapsulação, verificando o efeito da composição e estrutura da matriz lipídica. Para este propósito, foram caracterizadas as matérias-primas lipídicas em composição de ácidos graxos e triacilgliceróis, bem como, as misturas lipídicas avaliadas por calorimetria diferencial de varredura (DSC), teor de gordura sólida (SFC) e curva de isosólidos. Nas micropartículas, foram avaliadas morfologia de superfície e microestrutura, tamanho e distribuição de partícula, quantidade de glicose superficial (não encapsulada), eficiência de encapsulação e perfil de liberação em solução aquosa. As micropartículas apresentaram formas esféricas e rugosas, com diâmetros médios entre 83 e 115 µm. Os resultados de eficiência de encapsulação nas misturas do AE e STH foram acima de 75% e nas misturas do ACE menor que 9%. A liberação do recheio foi avaliada a cada 30 minutos por 2 horas, obtendo-se valores de 28 a 89% ao término deste período para as misturas do AE e STH. Foi observado, nestas misturas, que a liberação de recheio é inversamente proporcional à quantidade de AO na mistura lipídica. Nas misturas do ACE, a liberação foi de 100% (efeito burst). A adição do lipídio líquido (AO) ao lipídio sólido (AE e STH) foi um fator determinante na modificação da cristalização da mistura lipídica, proporcionando uma alta eficiência de encapsulação / Abstract: The ease to obtain lipid microparticles and the possibility of their production in an industrial scale increase the interest of the food market to process this kind of particles. However, these microparticles present disadvantages with regard to low encapsulation and the expulsion of the core material core during storage. Thus, the purpose of this work was to study the behavior of lipid microcapsules produced by the spray chilling process, using the following mixtures in different proportions: stearic acid (SA) and oleic acid (OA), fully hydrogenated soybean oil (FHSO) and oleic acid (OA), cetostearyl alcohol (CEA) and oleic acid (OA) as the wall material (matrix), soy lecithin as surfactant and glucose solution as core. The objective was to increase the encapsulation efficiency, checking the composition effect and the lipid matrix structure. For this purpose, the lipid materials were characterized as to their fatty acids and triacylglycerol composition and the lipid mixtures were evaluated by differencial scanning calorimetry (DSC), solid fat content (SFC) and iso-solid curve. The surface morphology and microstructure were evaluated in the microparticles, as well as the particle size distribution, amount of core on the surface (not encapsulated), the encapsulation efficiency and controlled-release in an aqueous solution. The microparticles showed spherical and wrinkled shape with average diameters between 83 and 115 µm. The results of encapsulation efficiency of the mixtures with SA and FHSO were over 75% and lower than 9% in the mixtures with CEA. The core release was evaluated every 30 minutes for 2 hours obtaining values from 28 to 89% at the end of this period for the mixtures SA and FHSO. It was observed, in these mixtures, that the core release is inversely proportional to the quantity of AO in the lipid mixture. In the CEA mixtures, the core release was above 100% (burst effect). The addition of the liquid lipid (OA) to the solid lipid (SA and FHSO) was a determining factor in the modification of the crystallization of the lipid mixture providing high encapsulation efficiency / Mestrado / Mestre em Tecnologia de Alimentos

Doctor of Philosophy / Department of Physics / Bruce M. Law / We have studied two critical binary liquid mixtures in the mixed phase regime with x-ray and neutron reflectometry to verify universal critical scaling at a non-critical interface. We compared our results with previous results obtained with ellipsometry. At a solid-liquid or liquid-vapor interface of an AB binary liquid mixture the component with the lower surface tension will dominate that interface. If the surface tension differential between the components of the mixture is large enough the composition of the surface layer will loose its dependence on. This case is referred to as strong adsorption. We study the case of strong adsorption for a binary liquid mixture at the critical composition with respect to the demixing phase transition. Sufficiently close to the critical temperature Tc the influence of bulk critical behavior is expected to dominate the way the surface adsorption layer decays with depth z from the surface composition to the bulk composition. The length scale of the decay profile is expected to be proportional to the composition correlation length, and is expected to scale with a universal composition scaling function. In a neutron reflectometry study of a critical mixture of D2O and 3-methylpyridine against a quartz substrate we verify universal critical scaling using a scaling function previously used to describe ellipsometry data. In an x-ray reflectometry study of the liquid-vapor interface of a critical mixture of n-dodecane and 1,1,2,2 tetrabromoethane, which had previously been studied with ellipsometry, we find that we are able to describe all data by using the same scaling function provided that we account for non-critical, system dependent surface structure as well. We are also able to simulate ellipsometry with our mathematical profile model and compare the simulation to the previous ellipsometry data.

>Magister Scientiae - MSc / Fuel cells are widely considered to be efficient and non-polluting power source offering much higher energy density. This study is aimed at developing oxygen reduction reactions (ORR) catalysts with reduced platinum (Pt) loading. In order to achieve this aim, monometallic Pd and Pt nanostructured catalysts were electrodeposited on a substrate (carbon paper) by surface limited redox replacement using electrochemical atomic layer deposition (ECALD) technique. Pd:Pt bimetallic nanocatalysts were also deposited on carbon paper. Pd:Pt ratios were (1:1, 2.1 and 3:1). The prepared mono and bimetallic catalysts were characterized using electrochemical methods for the ORR in acid electrolyte. The electrochemical characterization of these catalysts includes: Cyclic Voltammetry (CV) and linear sweep voltammetry (LSV). The physical characterization includes: scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) for Morphology and elemental composition, respectively. The deposition of copper (Cu) on carbon paper was done by applying a potential of -0.05 V at 60s, 90s and 120s. 8x cycles of Pt or Pd showed better electrochemical activity towards hydrogen oxidation reaction. Multiples of eight were used in this work to deposit Pt: Pd binary catalyst. Cyclic voltammetry showed high electroactive surface area for Pt24Pd24/Carbon-paper while LSV showed high current density and positive onset potential. HRSEM also displayed small particle size compared to other Pt:Pd ratios.