La supraconductivité non-conventionnelle a récemment été observée à proximité d'un point critique induit sous pression dans CePt$_2$In$_7$ et dans FeSe. Le premier est un fermion lourd tandis que le deuxième fait parti de la famille des supraconducteurs à base de Fer. Cette thèse a pour objectif de contribuer à la compréhension de ces systèmes à électrons fortement corrélés en étudiant les évolutions des structures cristallographiques et magnétiques, ainsi que les surfaces de Fermi sous conditions extrêmes.Tout d'abord, nous présentons une étude de diffraction de neutrons dans la phase magnétique de CePt$_2$In$_7$. Une seule structure magnétique, avec comme vecteur de propagation $textbf{Q} = (0.5,0.5,0.5)$ et $0.45~mu_B$ par atome de Cérium à 2 K, a été détectée en dessous de $T_N = 5.5$ K.Ensuite, des mesures de torque sous champ pulsé de CePt$_2$In$_7$ ne montrent aucun changement des surfaces de Fermi jusqu'à 70 T, bien au-dessus du point critique quantique induit sous champ, attendu à $55-60$ T selon la littérature. Cependant, ces mesures révèlent une claire anomalie métamagnétique à 47 T, très peu dépendante de la température et de l'orientation du champ ainsi qu'une chute des masses effectives vers 50 T. Nous suggérons que ces deux derniers éléments sont la manifestation d'un changement de valence des atomes de Ce de l'ordre de 0.06 électron par atomes de Cérium.L'étude des surfaces de Fermi de CePt$_2$In$_7$ sous pression a nécessité un développement instrumental à partir d'un circuit résonant à base d'une diode tunnel, combinée avec une cellule de pression de type Bridgman. Nous montrons qu'il est tout à fait possible de sonder les surfaces de Fermi à la fois sous champ magnétique et sous pression avec cette technique. Cependant, la fragilité du système résonnant nous amène à considérer des améliorations en vue de fiabiliser la mesure.Enfin, nous analysons une expérience de diffraction de rayons X sur un échantillon de FeSe sous pression hydrostatique. A 20 K, nous quantifions un durcissement de l'axe cristallographique $c$ qui s'opère à 1.9 GPa. A 50 K, outre le passage d'une maille orthorhombique à tétragonale à 1 GPa, nous mettons en évidence qu'une symétrie monoclinique s'installe à partir de 2 GPa, où, selon la littérature, une phase antiferromagnétique apparaît. / Unconventional superconductivity was recently observed in the vicinity of a pressure-induced quantum critical point in CePt$_2$In$_7$ and FeSe. The former is a heavy fermion compound, while the latter is an iron-based superconductor. This PhD thesis aims at improving our understanding of the physics of these newly discovered strongly correlated electron systems. This is achieved by experimental investigation of the evolution of crystal and magnetic structures, as well as of the Fermi surfaces under extreme conditions of high magnetic fields, high pressure, and low temperatures.We have investigated the magnetic structure of CePt$_2$In$_7$ by neutron diffraction. We observed only one magnetic propagation vector $textbf{Q} = (0.5, 0.5, 0.5)$ below $T_N = 5.5$ K. The magnetic moment is estimated at $0.45~mu_B$ per cerium atom at 2 K.Our torque measurements on CePt$_2$In$_7$ in pulsed fields suggest that the Fermi surfaces remain unchanged up to 70 T. This is well above the field-induced quantum critical point, which is expected to occur at $55-60$ T according to previous studies. However, a clear metamagnetic-like anomaly is found at 47 T. The anomaly is almost temperature and field-angle independent. Furthermore, a sudden drop of the effective mass is observed at about the same field. We suggest that the last two observations are most naturally accounted for by a valence crossover, where the cerium valence changes by about 0.06, the order of magnitude expected in Ce-based compounds.In order to study the Fermi surfaces of CePt$_2$In$_7$ under pressure, we developed a tunnel diode oscillator combined with a Bridgman-type pressure cell. We have demonstrated that this set-up is suitable for measuring quantum oscillations both at high magnetic fields and under high pressure. However, the working conditions of the oscillator have to be improved in order to obtain a more reliable system.Finally, we performed an X-ray diffraction experiment on FeSe under hydrostatic pressure. At 20 K, we found a change of the bulk modulus along the $c$ axis at 1.9 GPa. At 50 K, the orthorhombic to tetragonal crystallographic phase transition occurs at 1 GPa. We found evidences that this is followed by the emergence of a monoclinic symmetry above 2 GPa, where an antiferromagnetic phase was previously reported.

As principais matérias primas necessárias para a preparação de testes diagnósticos são as proteínas dos patógenos que necessariamente apresentem as estruturas nativas. O objetivo do presente estudo foi a obtenção das proteínas não estruturais 1 (NS1) dos vírus da dengue (DENV) e da zika (ZIKV) a partir dos corpúsculos de inclusão (CI) produzidos em bactérias Escherichia coli. Mostramos que a combinação de alta pressão hidrostática (APH) e pH alcalino é eficiente para a solubilização de NS1-CI. A incubação em 2,4 kbar das suspensões de NS1-CI em pH alcalino mostrou-se eficiente para a solubilização da NS1. A presença de Arg promove a dissociação de oligômeros. A aplicação de 2,4 kbar às suspensões de NS1-CI em pH de 10,5 (DENV) e de 11,5 (ZIKV) na presença de Arg e um par redox, seguida de diálise em tampão em pH 8,5, foram as condições escolhidas para o reenovelamento de NS1. Obtivemos ambas NS1 com rendimentos entre 75% e 90% em relação às quantidades totais das proteínas presente nos correspondentes CI de NS1. As NS1 reenoveladas apresentaram reatividade comparável às proteínas obtidas utilizando um protocolo convencional estabelecido, com rendimentos mais de 25 vezes superiores. Foi obtido um processo altamente eficiente para o reenovelamento de NS1 apresentando características biológicas preservadas em relação a reatividade com anticorpos específicos de antígeno, incluindo soro de paciente infectado com zikv e que, portanto, podem ser usados como antígeno para o desenvolvimento de vacinas ou testes de diagnóstico. Além disso, este estudo descreve a criação de um processo inovador, que é a utilização concomitante de APH e pH alcalino, para solubilização e posterior reenovelamento de NS1-CI que podem ser utilizados para outras proteínas relevantes. / The main products for the preparation of diagnostic tests are as proteins of the pathogens that necessarily present as the native structures. The objective of the present study was to obtain non-structural proteins 1 (NS1) from dengue virus (DENV) and zika virus (ZIKV) from the inclusion bodies (IBs) produced in Escherichia coli bacteria. We show that it is a combination of high hydrostatic pressure (HHP) and alkaline pH is efficient for a solubilization of NS1-IB. A 2.4 kbar incubation of NS1-IB suspensions at alkaline pH proved to be efficient for NS1 solubilization. The presence of Arg promotes the dissociation of oligomers. The application of 2.4 kbar to the suspensions of NS1-IB at pH 10.5 (DENV) and 11.5 (ZIKV) in the presence of Arg and a redox pair, dialysis in pH 8.5 buffer were as conditions chosen for the refolding of NS1. We obtained both NS1 at yields between 75% and 90% relative to the total amounts of the proteins present in the corresponding NS1 IB. Refolded NS1 showed similar to proteins obtained using an established standard protocol, with yields more than 25 times higher. A highly efficient process for the refolding of NS1 was obtained with preserved biological features regarding reactivity with antigen-specific antibodies, including sera of zikv-infected patients and that can be used as antigen for the development of vaccines or diagnostic tests. In addition, this study describes the creation of an innovative process, which is a concomitant use of HHP and alkaline pH, for solubilization and subsequent refolding of NS1-IB that can be used for other relevant proteins.

Os compostos antioxidantes naturais têm sido cada vez mais investigados devido à necessidade das indústrias alimentícias suprirem as exigências dos consumidores em relação à saudabilidade dos produtos. A quercetina é um flavonoide cujos benefícios estão relacionados principalmente à sua ação antioxidante. Entretando, tal molécula apresenta, geralmente, baixa absorção no trato gastrointenstinal, o que pode ser um obstáculo para sua efetiva ação biológica. Por este motivo, uma alternativa para melhorar a sua bioacessibilidade é a encapsulação em sistemas coloidais baseados em matrizes lipídicas, como os lipossomas. Os lipossomas possuem a capacidade de incorporar tanto bioativos hidrofílicos quanto hidrofóbicos em sua estrutura, bem como proporcionar liberação controlada e aumentar a bioacessibilidade dos ingredientes encapsulados. No entanto, há necessidade do desenvolvimento de processos de produção de lipossomas em maior escala, e dentre os processos possíveis a serem empregados com este objetivo encontra-se o método de produção de injeção de etanol. O objetivo principal da presente Tese foi a microencapsulação de quercetina em lipossomas através do método de injeção de etanol. A dispersão de lipossomas encapsulando quercetina escolhida foi liofilizada, com a intenção de aumentar a estabilidade dos lipossomas e enriquecer o amido de milho. O enriquecimento do amido de milho foi realizado por aglomeração, especificamente pelo método de alto cisalhamento, sendo que o pó alimentício aglomerado resultante foi caracterizado fisicamente e teve suas propriedades físicas melhoradas. Foi possível realizar a aplicação do amido de milho enriquecido com quercetina no antepasto de berinjela, sendo que tal incorporação não alterou significativamente as características do produto. Além disso, o antepasto de berinjela foi processado a alta pressão hidrostática e teve sua estabilidade avaliada, sendo que a utilização do processamento não-térmico apresentou vantagens em relação ao método de processamento convencional. / The natural antioxidant compounds have been increasingly investigated due to the need of the food industry to provide healthier products. Quercetin is a flavonoid, whose benefits are linked mainly with its antioxidant activity. However, this bioactive generally has a low absorption rate in the gastrointestinal tract, which it can be an obstacle for its biological action effective. For this reason, an alternative to improve such bioavailability is to encapsulate quercetina in lipid-based matrices, e.g, liposomes. The liposomes have the capacity to encapsulate both hydrophilic and hydrophobic bioactive, as well as to control the release of the encapsulated bioactives, and enhance their bioavailability. However, there is a need to develop liposome production methods in larger scale, and one of the processes feasible to be scaled up is the ethanol injection method. One of the main objectives of this Thesis was to microencapsulate quercetin in liposomes by ethanol injection method. The dispersion of quercetin-loaded liposomes was lyophilized aiming to increase the stability of liposomes and enrich cornstarch. The enrichment of cornstarch was performed by agglomeration, specifically by high shear method, and the agglomerated food powders were characterized and their physical properties was improved. It was possible to incorporate the enriched cornstarch with quercetin in eggplant sauce, and such application did not change the product characteristics. Also, the eggplant sauce was processed by high hydrostatic pressure and had its stability evaluated, indicating the use of nonthermal technology showed advantages if compared to the conventional thermal processing.

As principais matérias primas necessárias para a preparação de testes diagnósticos são as proteínas dos patógenos que necessariamente apresentem as estruturas nativas. O objetivo do presente estudo foi a obtenção das proteínas não estruturais 1 (NS1) dos vírus da dengue (DENV) e da zika (ZIKV) a partir dos corpúsculos de inclusão (CI) produzidos em bactérias Escherichia coli. Mostramos que a combinação de alta pressão hidrostática (APH) e pH alcalino é eficiente para a solubilização de NS1-CI. A incubação em 2,4 kbar das suspensões de NS1-CI em pH alcalino mostrou-se eficiente para a solubilização da NS1. A presença de Arg promove a dissociação de oligômeros. A aplicação de 2,4 kbar às suspensões de NS1-CI em pH de 10,5 (DENV) e de 11,5 (ZIKV) na presença de Arg e um par redox, seguida de diálise em tampão em pH 8,5, foram as condições escolhidas para o reenovelamento de NS1. Obtivemos ambas NS1 com rendimentos entre 75% e 90% em relação às quantidades totais das proteínas presente nos correspondentes CI de NS1. As NS1 reenoveladas apresentaram reatividade comparável às proteínas obtidas utilizando um protocolo convencional estabelecido, com rendimentos mais de 25 vezes superiores. Foi obtido um processo altamente eficiente para o reenovelamento de NS1 apresentando características biológicas preservadas em relação a reatividade com anticorpos específicos de antígeno, incluindo soro de paciente infectado com zikv e que, portanto, podem ser usados como antígeno para o desenvolvimento de vacinas ou testes de diagnóstico. Além disso, este estudo descreve a criação de um processo inovador, que é a utilização concomitante de APH e pH alcalino, para solubilização e posterior reenovelamento de NS1-CI que podem ser utilizados para outras proteínas relevantes. / The main products for the preparation of diagnostic tests are as proteins of the pathogens that necessarily present as the native structures. The objective of the present study was to obtain non-structural proteins 1 (NS1) from dengue virus (DENV) and zika virus (ZIKV) from the inclusion bodies (IBs) produced in Escherichia coli bacteria. We show that it is a combination of high hydrostatic pressure (HHP) and alkaline pH is efficient for a solubilization of NS1-IB. A 2.4 kbar incubation of NS1-IB suspensions at alkaline pH proved to be efficient for NS1 solubilization. The presence of Arg promotes the dissociation of oligomers. The application of 2.4 kbar to the suspensions of NS1-IB at pH 10.5 (DENV) and 11.5 (ZIKV) in the presence of Arg and a redox pair, dialysis in pH 8.5 buffer were as conditions chosen for the refolding of NS1. We obtained both NS1 at yields between 75% and 90% relative to the total amounts of the proteins present in the corresponding NS1 IB. Refolded NS1 showed similar to proteins obtained using an established standard protocol, with yields more than 25 times higher. A highly efficient process for the refolding of NS1 was obtained with preserved biological features regarding reactivity with antigen-specific antibodies, including sera of zikv-infected patients and that can be used as antigen for the development of vaccines or diagnostic tests. In addition, this study describes the creation of an innovative process, which is a concomitant use of HHP and alkaline pH, for solubilization and subsequent refolding of NS1-IB that can be used for other relevant proteins.

Les cuprates sont des matériaux que l’on peut faire passer d'un isolant antiferromagnétique à un métal normal en augmentant leur densité de porteurs par dopage chimique. Aux dopages intermédiaires, une riche variété de phases électroniques apparaît aux côtés de la phase supraconductrice, ou même entrelacée avec elle. Le but de cette thèse était de caractériser divers aspects de la compétition entre la supraconductivité et les ordres de charge ou de spin, en utilisant la résonance magnétique nucléaire (RMN). Une première partie du travail a consisté à améliorer la modélisation des spectres RMN des noyaux de 17O dans les deux phases onde de densité de charge (ODC) présentes dans YBa2Cu3Oy: l’ordre à courte portée et l’ordre à longue portée (induit par le champ magnétique). En plus de fournir un cadre d'analyse beaucoup plus précis pour les données de RMN en fonction du champ, du dopage et de la pression (voir ci-après), les résultats indiquent que l’ODC à haut champ est uni-axiale (c'est-à-dire avec un vecteur d'onde unique q), avec une période commensurable avec le réseau de trois cellules unitaires (q = 1/3). Le deuxième aspect de la compétition de phases abordé dans ce travail est l'effet (controversé) de la pression hydrostatique. Nos mesures montrent qu'une pression de 1,9 GPa n'affaiblit que très légèrement l’ODC à courte portée dans l'état normal ainsi que l’ODC à longue portée observée à haut champ. Les résultats soutiennent l’hypothèse selon laquelle l'augmentation continue de Tc lorsque la pression augmente jusqu'à 15 GPa est presque entièrement due à une diminution progressive de la force de l’ODC. Ceci montre que la pression hydrostatique est un paramètre permettant de contrôler la compétition entre l’ODC et la supraconductivité dans les cuprates.Dans la troisième partie de la thèse, des mesures du taux de relaxation spin-réseau (1/T1) des noyaux de 139La ont permis d’étudier l'effet d'un champ magnétique sur la mise en ordre vitreuses des spins dans La2-xSrxCuO4. En utilisant des champs élevés jusqu’à 45 T, nous montrons que le champ est capable d’induire une phase gelée, ou presque gelée, à des niveaux de dopage bien supérieurs à ceux supposés précédemment, à savoir jusqu’au dopage critique attribué à l’extrémité de la phase pseudogap mais pas au-delà de ce point, ou pas loin au-delà. Ce résultat a des implications importantes pour l'interprétation de la phase de pseudogap et de la criticité quantique qui lui est associée. / Cuprates are materials that can be tuned from an antiferromagnetic insulator to a normal metal by increasing the carrier density through chemical doping. At intermediate doping, a rich variety of electronic phases emerges alongside, or intertwined, with the superconducting phase. The aim of this thesis was to characterise various aspects of the competition between superconductivity and charge or spin order, using nuclear magnetic resonance (NMR).A first part of the work consisted in improving the modelling of 17O NMR spectra in the two charge-density wave (CDW) phases present in YBa2Cu3Oy: the short-range order and the (magnetic-field induced) long-range order. Besides providing a much more accurate analysis framework for NMR data as a function of field, doping and pressure (see hereafter), the results indicate that the CDW in high-fields is uniaxial (i.e. single wave vector q) and commensurate with the lattice, with a period of three unit cells (q=1/3).The second aspect of phase competition addressed in this work is the (controversial) effect of hydrostatic pressure. Our measurements show that a pressure of 1.9 GPa weakens the short-range CDW in the normal state and the long-range CDW observed in high fields only slightly. The results support the proposal that the continuous rise in Tc upon increasing pressure up to 15 GPa arises almost entirely from a gradual decrease of the CDW strength. This establishes hydrostatic pressure as a tuning parameter of the competition between CDW order and superconductivity in the cuprates.In the third part of the thesis, 139La spin-lattice relaxation rate (1/T1) measurements were used to study the effect of a magnetic field on glassy spin ordering in La2-xSrxCuO4. Using high fields up to 45 T, we reveal that the field is able to induce a frozen, or nearly so, phase at doping levels much higher than previously assumed, namely up to the putative endpoint of the pseudogap boundary, but not, or not far, beyond that point. This result has important implications for interpreting the pseudogap phase and its associated quantum criticality.

Les équations fondamentales décrivant la dynamique de l'océan sont en théorie les équations de Navier-Stokes sur une sphère en rotation, auxquelles il faut a jouter une équation d'état pour la densité, et des équations de transport-diffusion pour les traceurs. Toutefois, un certain nombre de considérations physiques et de limitations pratiques ont nécessité le développement de modèles plus simples. En effet, un certain nombre d'hypothèses simplificatrices sont pleinement justifiées du point de vue de la physique des mouvements océaniques, dont les principales sont les approximations de couche mince et de Boussinesq. D'autre part, étant donné les dimensions des bassins océaniques (plusieurs centaines à plusieurs milliers de kilomètres), les coûts de calculs sont un facteur pratique extrêmement limitant. On est, à l'heure actuelle, capable de simuler l'océan mondial avec une résolution de l'ordre de dix kilomètres, en utilisant des modèles dits aux équations primitives, dont le coût de calcul est bien inférieur à celui des équations de Navier-Stokes. On est donc bien loin d'une modélisation complète des phénomènes décrits par ces équations, qui nécessiterait en théorie de considérer des échelles de l'ordre du millimètre. Les équations primitives sont issues des équations complètes de la mécanique des fluides en effectuant l'approximation hydrostatique, justifiée par la faible profondeur des domaines considérés au regard de leur dimension horizontale. Dans cette thèse, nous considérerons les équations de Navier-Stokes (NS) qui sont le coeur du modèle complet évoqué ci-dessus, sans prendre en compte les équations de la densité et des traceurs (salinité, température, etc.). Nous utiliserons l'approximation hydrostatique dans le chapitre 10, et le modèle sera naturellement appelé Navier-Stokes hydrostatique (NSH). Il correspond aux équations primitives dans lesquelles on ne prendrait pas en compte la densité et les traceurs. C'est dans ce cadre que se situe le travail présenté dans cette thèse, avec l'objectif à moyen terme de pouvoir coupler de façon rigoureuse et efficace les équations de Navier-Stokes avec les équations primitives. Dans une première partie, on présentera quelques rappels sur les équations de Navier-Stokes, leur discrétisation, ainsi que le cas-test de la cavité entraînée qui sera utilisé dans tout ce document. Dans une deuxième partie, on met en œuvre les méthodes de Schwarz sur les équations de Stokes et Navier-Stokes, en dérivant notamment des conditions absorbantes exactes et approchées pour ces systèmes. Enfin, dans une troisième partie, on proposera des pistes vers le couplage Navier-Stokes/Navier-Stokes hydrostatique décrit ci-dessus. / Fundamental equations describing the ocean dynamic are theoretically Navier-Stokes equations over a rotating sphere, whom need to add a state equation for the fluid density, and advection-diffusion equations for tracers. However, some physical considerations and practical limitations required to developped more simple models. Indeed, some simplifying hypotheses are well justified from a ocean dynamic point of view, whose principal ones are thin layer and Boussinesq approximations. On the other hand, considering the dimensions of oceans (from serveral hundreds to serveral thousands kilometers), computations costs are a very practical limitating factor. We are, by now, able to simulate the global ocean with about ten kilometers large grid mesh. This is very far from a complete modelisation of all phenomenes decribed by the Navier-Stokes equations, which require to consider scales of milimeters order. Primitives equations derive from complete equations describing fluid mecanics, by doing the hydrostatic approximations, which is justified by the low deepness of considered domains with regard to their horizontal dimension. In this thesis, we are considering Navier-Stokes equations (NS) which are the heart of the complete modele mentionned previously, without holding in account density and tracers equations. We will use the hydrostatic approximations, and the resulting equations will be named as hydrostatic Navier-Stokes equations (NSH).The mid term objective is to couple carefully Navier-Stokes equations with primitive equation. In a first part, we will remind few results for Navier-Stokes equations, their discretization, and the lid-driven cavity which wil be used as a test-case. In a second part, we will use Schwarz method with Stokes and Navier-Stokes equations, deriving in particular exact and approched absorbing interface conditions for these systems. Finally, in a third part, we shall propose first results towards coupling Navier-Stokes and hydrostatic Navier-Stokes equations.

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-07-21T18:04:23Z No. of bitstreams: 1 CarlosSantos.pdf: 7721249 bytes, checksum: ee220ca2d9a3d156b8c575c28854ffea (MD5) / Made available in DSpace on 2017-07-21T18:04:23Z (GMT). No. of bitstreams: 1 CarlosSantos.pdf: 7721249 bytes, checksum: ee220ca2d9a3d156b8c575c28854ffea (MD5) Previous issue date: 2017-02-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / In this work L-tyrosine hydrochloride crystals (LTHCl) were prepared by slow evaporation technique at room temperature and characterization by X-ray diffraction, thermogravimetry, differential thermal analysis, differential scanning calorimetry and Raman scattering at room temperature and under high pressures. After four weeks, it was possible obtain various crystals of good crystalline quality. The solution was acidic with pH 1.2. From the XRD pattern of the material and the Rietveld analysis, it was found that at room temperature LTHCl crystallizes in monoclinic space group (P21) with two molecules per unit cell. The refinement quality parameters were satisfactory with Rp = 6.29 %, Rwp = 8.49 % and S = 1.34. The thermal analysis showed that the material undergoes fusion around 231°C and presented no thermal event that features phase transition before the fusion. Furthermore, thermal analysis showed that the crystal is stable up to 220°C. Calculations using DFT (Functional Density Theory) were performed to identify the vibrational modes in the LTHCl crystal. Raman scattering measurements as a function of pressure (0,0-7,2 GPa) showed as major changes: the occurrence of an inversion of intensity between a strong band (attributed to torsion of L-tyrosine molecule) and an imperceptible band (at ambient pressure) for pressures above 2,5 GPa and a discontinuity of dω/dP associated with the strong band between 1.0 and 1.5 GPa, suggesting a conformational transition above 1.5 GPa stabilizing the structure up to 7,2 GPa. In the region of the internal modes few changes were observed, with the downshift of the COOH and NH3+ units as one of them. Finally, the decompression reinforced that the conformational phase transition is reversible, demonstrating a great capacity of this material to regenerate its original structure without presenting hysteresis. / Neste trabalho foram sintetizados cristais de L-tirosina hidroclorídrica (LTHCl) pela técnica de evaporação lenta do solvente à temperatura ambiente e realizadas medidas de caracterização por difração de raios X, análise térmica diferencial, análise termogravimétrica, calorimetria exploratória diferencial e espalhamento Raman à temperatura ambiente e a altas pressões neste sal de aminoácido. Após quatro semanas foram obtidos vários cristais, que apresentaram, visualmente, boa qualidade cristalina. A solução de crescimento era ácida com pH 1,2. Através do difratograma do material e da análise pelo método de Rietveld, constatouse que à temperatura ambiente a LTHCl cristaliza-se numa estrutura monoclínica (P21) com duas moléculas por célula unitária. Os parâmetros de qualidade do refinamento foram satisfatórios, com Rp = 6,29 %, Rwp = 8,49 % e S = 1,34. As análises térmicas mostraram que o material sofre fusão por volta de 231°C e que não há evento térmico que caracterize uma transição de fase antes da fusão. Além disso, as análises térmicas mostraram que o cristal é estável até 220°C. Cálculos usando a Teoria do Funcional de Densidade (DFT, density funcional theory) foram realizados para a identificação dos modos vibracionais no cristal de LTHCl. As medidas de espalhamento Raman em função da pressão (0,0-7,2 GPa) apresentaram como principais mudanças: A ocorrência de uma inversão de intensidade entre uma forte banda (associada à torção da molécula de L-tirosina) e uma banda imperceptível (à pressão ambiente) para pressões acima de 2,5 GPa, bem como a descontinuidade em dω/dP da forte banda entre 1,0 e 1,5 GPa, sugerindo uma mudança conformacional indicada pela torção da molécula de L-tirosina para pressões acima de 1,5 GPa deixando a estrutura estável até 7,2. Na região dos modos internos foram observadas poucas mudanças, tendo o downshift das unidades COOH e NH3 + como uma delas. Finalmente, a descompressão reforçou que a transição de fase conformacional é reversível, demonstrando uma grande capacidade desse material para se regenerar, sem apresentar histerese.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-10-19T17:51:25Z No. of bitstreams: 1 2013 - Ellen Almeida dos Santos Ferreira.pdf: 1317610 bytes, checksum: dd687bdd4e12dc0f868a15a961aa31ed (MD5) / Made available in DSpace on 2018-10-19T17:51:25Z (GMT). No. of bitstreams: 1 2013 - Ellen Almeida dos Santos Ferreira.pdf: 1317610 bytes, checksum: dd687bdd4e12dc0f868a15a961aa31ed (MD5) Previous issue date: 2013-05-06 / Brazil is a big producer and exporter of fruits and fruit juice. The sale, in many cases, is limited to the seasonality of production and perishability of fruits. The Brazilian cherry is a tropical fruit originally from the South and Southeast regions of Brazil, with high perishability and susceptibility to physical damage during transport. Considering all the losses that the productive chain of fresh Brazilian cherry may suffer, it is evident the importance of producing the juice of this fruit. Traditionally, thermal treatment has been employed in the processing and preservation of these products; however, undesirable changes in sensory and nutritional characteristics can happen. Among the innovative technologies to reduce these undesirable changes is High Hydrostatic Pressure (APH). This method of food preservation provides additional benefits to the product allowing products closer to the fresh product. This study aimed to investigate the process of high pressure in the preservation of Brazilian cherry pulp (Eugenia uniflora L.) to assess their microbiological safety and sensory quality and nutritional nectar obtained. The study was conducted at Embrapa Food Technology (Rio de Janeiro-RJ, Brazil). The Brazilian cherry pulp was processed by high hydrostatic pressure using different pressure levels, temperatures and retention time, following a central composite design. Microbiological analyzes were performed (for Salmonella spp., Coliforms at 45? C, mesophilic aerobic, yeasts and molds), physico-chemical (pH, acidity, soluble solids, fibers), antioxidant activity and instrumental color. It was investigated nectar microbiological shelf life obtained from the pressurized pulp. Shelf life estimation through Survival Analysis was also carried out, and the nectar exceeded 35 days of storage. Further studies are recommended. The sensory characteristics of nectars obtained from the pressurized pulp, non-pressurized pulp (Control), pasteurized Control, and three commercial brands available in the market were evaluated by consumer acceptance and through the methodology check all that apply (CATA). Data were analyzed using analysis of variance, Tukey test, and Multiple Factor Analysis. The high pressure process has been effective in preserving the nectar refrigerated for up to 35 days. There was no significant negative effect on antioxidant activity and color of the samples subjected to high pressure. The results obtained in the determination of "ideal" pulp concentration and sweetness for the nectar formulation cherry were 36% and 10%, respectively. In Acceptance Test samples pressurized and commercial B had the highest scores and the terms most frequently used in the methodology check all that apply were reddish, cherry flavor, presence of particles, attractive color, acid, astringent, off-flavor, sweet, bitter, gritty look. Such terms are therefore considered the most suitable to describe the samples by consumers. / O Brasil ? um grande produtor e exportador de frutas e suco de frutas. A comercializa??o, em muitos casos, ? limitada ? sazonalidade da produ??o e ? perecibilidade das frutas. A pitanga ? uma fruta tropical origin?ria das regi?es Sul e Sudeste do Brasil, com alta perecibilidade e susceptibilidade a danos f?sicos durante o transporte. Tendo em vista todas as perdas que a cadeia produtiva da pitanga in natura pode sofrer, fica evidente a relev?ncia da obten??o do suco deste fruto. Tradicionalmente o tratamento t?rmico tem sido empregado no processamento e conserva??o destes produtos; no entanto, altera??es indesej?veis nas caracter?sticas nutricionais e sensoriais podem acontecer. Entre as tecnologias inovadoras para redu??o dessas altera??es indesej?veis, est? a Alta Press?o Hidrost?tica (APH). Este m?todo de conserva??o de alimentos oferece benef?cios adicionais ao produto permitindo a obten??o com caracter?sticas mais pr?ximas do produto in natura. Este estudo teve como objetivo investigar o processo de alta press?o na conserva??o de polpa de pitanga (Eugenia uniflora L.) de modo a avaliar a seguran?a microbiol?gica e a qualidade sensorial e nutricional do n?ctar obtido. O trabalho foi realizado na Embrapa Agroind?stria de Alimentos (Rio de Janeiro, RJ, Brasil). A polpa de pitanga foi processada por alta press?o hidrost?tica utilizando diferentes n?veis de press?o e tempo de reten??o, seguindo delineamento experimental do tipo composto central. Foram realizadas an?lises microbiol?gicas (para Salmonella spp., coliformes ? 45?C, aer?bios mes?filos e fungos filamentosos e leveduras), f?sico-qu?micas (pH, acidez, s?lidos sol?veis, fibras), atividade antioxidante, cor instrumental e avalia??o sensorial. Foi avaliada a vida ?til microbiol?gica do n?ctar obtido a partir da polpa pressurizada e sensorialmente atrav?s da an?lise de sobreviv?ncia (Survival Analysis). O n?ctar apresentou vida ?til superior a 35 dias, necessitando estudos subsequentes. As caracter?sticas sensoriais dos n?ctares obtidos a partir da polpa pressurizada, da polpa n?o pressurizada (controle), do controle pasteurizado e de tr?s marcas comerciais dispon?veis no mercado foram avaliadas atrav?s da aceita??o do consumidor e utilizando a metodologia check all that apply (CATA). Os dados foram analisados por An?lise de Vari?ncia, teste de m?dia, e An?lise M?ltipla de Fatores. O processamento da polpa por alta press?o foi eficaz na preserva??o do n?ctar refrigerado por at? 35 dias. N?o houve efeito negativo da APH na atividade antioxidante das amostras. Nas an?lises de cor todos os par?metros analisados (L*, a* e b*) diferiram (p<0,05) do controle (polpa n?o pressurizada) e as amostras pressurizadas. Os resultados obtidos na determina??o de concentra??o de polpa e do?ura ?ideais? para a formula??o do n?ctar de pitanga foram 36% e 10%, respectivamente. No Teste de Aceita??o as amostras pressurizada e comercial B obtiveram as maiores m?dias e na metodologia check all that apply, os termos utilizados mais frequentemente como descritores foram cor avermelhada, sabor de pitanga, presen?a de part?culas, cor atrativa, ?cido, adstringente, sabor estranho, gosto doce, gosto amargo, aspecto arenoso. Tais termos podem ser, portanto, considerados os mais apropriados na descri??o das amostras pelos consumidores.

The non-hydrostatic dynamical core ENDGame (Even Newer Dynamics for the General Atmospheric Modelling of the Environment) is extended into the thermosphere to test its feasability as a whole-atmosphere dynamical core that can simulate the large scale fluid dynamics of the whole atmosphere from the surface to the top of the thermosphere at 600km. This research may have applications in the development of a Sun-to-Earth modelling system involving the Met Office Unified Model, which will be useful for space weather forecasting and chemical climate modelling. Initial attempts to raise the top boundary of ENDGame above ∼100km give rise to instabilities. To explore the potential causes of these instabilities, a one dimensional column version of ENDGame: ENDGame1D, is developed to study the effects of vertically propagating acoustic waves in the dynamical core. A 2D ray-tracing scheme is also developed, which accounts for the numerical effects on wave propagation. It is found that ENDGame’s numerics have a tendency towards the excessive focussing of wave energy towards vertical propagation, and have poor handling of large amplitude waves, also being unable to handle shocks. A key finding is that the physical processes of vertical molecular viscosity and diffusion prevent the excessive growth of wave amplitudes in the thermosphere in ENDGame, which may be crucial to improving ENDGame’s stability as it is extended upwards. Therefore, a fully implicit-in-time implementation of vertical molecular viscosity and diffusion is developed in both ENDGame1D and the full three-dimensional version of ENDGame: ENDGame3D. A new scheme is developed to deal with the viscous and diffusive terms with the dynamics terms in a fully coupled way to avoid time-splitting errors that may arise. The combination of a small amount of off-centring of ENDGame’s semi-implicit formulation and the inclusion of vertical molecular viscosity and diffusion act to make ENDGame significantly more stable, as long as the simulation is able to remain stable up to the molecularly diffused region above an altitude of ∼130km.

The behaviour of electrons in nanostructures such as quantum wells is of interest for the design of new electronic and electro-optic devices, and also for exploration of basic many-body physics. This thesis develops and tests improved methods for describing such electronic behaviour. The system used for this work was the parabolic quantum well (PQW), an important special system which has recently attracted much experimental and theoretical attention. We firstly report self-consistent nonlinear groundstate solutions of the Poisson equation together with the Thomas-Fermi (TF) hydrostatic equations. In contrast to most previous solutions, all the electron density profiles were inhomogeneous and continuous. We also added a von Weizsacker term with and without the exchange/exchange-correlation to the above treatment, using a novel numerical approach allowing for wider electron gases than previously possible. We also report for the first time the effects of spatially varying effective mass and dielectric function in theories of this type. To investigate infrared response of these systems, we apply new hydrodynamic theories recently proposed by Dobson. By using this type of theory, we simultaneously satisfy the Harmonic Potential Theorem (extended generalized Kohn theorem) and obtain the correct 2D plasmon dispersion, as well as obtaining the correct spacing of standing plasmons. Other inhomogeneous hydrodynamic theories do not achieve this. We also showed analytically an exact solution for a plasmon mode at the Kohn frequency in addition to one found in the Harmonic Potential Theorem. An open hydrodynamic theory was then developed based on this type of mode. Numerical application of Kohn Frequency Theorem theory was shown and the results were compared with other existing hydrodynamic theories.