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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Efeito da interesterificação química sobre as propriedades físico-químicas de misturas de estearina e oleína de palma / Effects of chemical interesterification on physical and chemical properties of blends of palm stearin and palm olein

Fabiana Andreia Schafer de Martini Soares 03 March 2010 (has links)
O desafio das indústrias de alimentos na substituição da gordura trans em diversos produtos reside no desenvolvimento de formulações e processos que apresentem funcionalidade equivalente e viabilidade econômica. A interesterificação química representa uma opção tecnológica importante para a produção de gorduras visando diversas aplicações comerciais, sem a formação de ácidos graxos trans. O óleo de palma contém quantidades aproximadamente iguais de ácidos graxos saturados e insaturados e pelo seu fracionamento obtêm-se duas frações: a estearina (fração sólida) e a oleína (fração líquida). A estearina e oleína de palma são opções interessantes para a produção de grande variedade de produtos como margarinas e shortenings. Assim, o objetivo deste trabalho foi modificar as propriedades físico-químicas de misturas de estearina e oleína de palma pelo uso da interesterificação química. As amostras foram analisadas quanto à composição em ácidos graxos e triacilgliceróis, distribuição regioespecífica dos ácidos graxos nos triacilgliceróis, índice de iodo, pontos de amolecimento e de fusão, conteúdo de gordura sólida, consistência e estrutura cristalina. Os ácidos graxos saturados são predominantes na estearina (71,9%), sendo que 65,5% correspondem ao ácido palmítico. A oleína tem como principal constituinte o ácido oléico, que representa 45,4%. À medida que aumenta a proporção de oleína de palma nas misturas, aumentam a quantidade de ácidos graxos insaturados e o índice de iodo e diminui a quantidade de ácidos graxos saturados. Após a interesterificação química, os pontos de fusão e amolecimento, a consistência e o conteúdo de gordura sólida aumentaram nas misturas que apresentavam maior proporção de oleína em função do aumento no teor de triacilgliceróis trissaturados. Por outro lado, estas propriedades não se modificaram nas misturas com maior proporção de estearina. Este comportamento se deve à distribuição aleatória dos ácidos graxos nos triacilgliceróis após a interesterificação, que forma triacilgliceróis em proporções diferentes das existentes originalmente. Os principais triacilgliceróis nas misturas foram PPP, PPO e POO. Antes da interesterificação os ácidos graxos saturados foram encontrados principalmente nas posições sn-1,3. Mudanças significativas na composição dos ácidos graxos na posição sn-2 após a interesterificação química foram encontradas em misturas com mais de 60% de oleína de palma. A mistura e a interesterificação permitiram obter gorduras com diferentes graus de plasticidade, aumentando as possibilidades de uso das frações estearina e oleína de palma. / The challenge of the food industries for the replacement of trans fat in various products lies in the development of formulations and processes which have equivalent functionality and economic viability. The chemical interesterification of palm stearin and palm olein is an important technological option for the production of fats targeting commercial applications, without formation of trans fatty acids Palm oil contains similar amounts of saturated and unsaturated fatty acids. After fractionation two fractions are obtained: stearin (solid fraction) and olein (liquid fraction). Palm stearin and palm olein are alternatives for the production of many products, such as margarines and shortenings. The objective of this work was to modify the physical and chemical properties of mixtures of palm stearin and palm olein by using chemical interesterification. The following properties were analyzed: fatty acid and triacylglycerol compositions, regiospecific distribution of fatty acids in triacylglycerols, iodine value, softening and melting points, solid fat content, consistency and crystal microstructure. Saturated fatty acids are predominant in palm stearin (71.9%), which corresponds to 65.5% of palmitic acid. Palm olein has as its main constituent the oleic acid, which represents 45.4% of the unsaturated fatty acids. The increase of the proportion of palm olein in the mixture causes increase on the amount of unsaturated fatty acids and iodine value and decrease on the content of saturated fatty acids. After chemical interesterification, melting and softening points, consistency and solid fat content increased in the blends that had higher proportion of palm olein, as a consequence of the increase in the trisaturated triacylglycerols. On the other hand, these properties did not alter in the blends with higher proportion of palm stearin. This behavior is due to the random distribution of fatty acids in triacylglycerols after interesterification, which forms triacylglycerols in proportions that are different from those originally present. The major triacylglycerols in the blends were PPP, PPO and POO. Before interesterification the saturated fatty acids were found mainly in the sn-1,3 positions. Significant changes in the fatty acid composition in the sn-2 position after chemical interesterification were found in blends with more than 60 % of palm olein. Blending and interesterification of fats resulted in structured lipids with different degrees of plasticity, increasing the possibilities of use of stearin and olein fractions.
122

Efeito da interesterificação química sobre as propriedades físico-químicas de misturas de estearina e oleína de palma / Effects of chemical interesterification on physical and chemical properties of blends of palm stearin and palm olein

Soares, Fabiana Andreia Schafer de Martini 03 March 2010 (has links)
O desafio das indústrias de alimentos na substituição da gordura trans em diversos produtos reside no desenvolvimento de formulações e processos que apresentem funcionalidade equivalente e viabilidade econômica. A interesterificação química representa uma opção tecnológica importante para a produção de gorduras visando diversas aplicações comerciais, sem a formação de ácidos graxos trans. O óleo de palma contém quantidades aproximadamente iguais de ácidos graxos saturados e insaturados e pelo seu fracionamento obtêm-se duas frações: a estearina (fração sólida) e a oleína (fração líquida). A estearina e oleína de palma são opções interessantes para a produção de grande variedade de produtos como margarinas e shortenings. Assim, o objetivo deste trabalho foi modificar as propriedades físico-químicas de misturas de estearina e oleína de palma pelo uso da interesterificação química. As amostras foram analisadas quanto à composição em ácidos graxos e triacilgliceróis, distribuição regioespecífica dos ácidos graxos nos triacilgliceróis, índice de iodo, pontos de amolecimento e de fusão, conteúdo de gordura sólida, consistência e estrutura cristalina. Os ácidos graxos saturados são predominantes na estearina (71,9%), sendo que 65,5% correspondem ao ácido palmítico. A oleína tem como principal constituinte o ácido oléico, que representa 45,4%. À medida que aumenta a proporção de oleína de palma nas misturas, aumentam a quantidade de ácidos graxos insaturados e o índice de iodo e diminui a quantidade de ácidos graxos saturados. Após a interesterificação química, os pontos de fusão e amolecimento, a consistência e o conteúdo de gordura sólida aumentaram nas misturas que apresentavam maior proporção de oleína em função do aumento no teor de triacilgliceróis trissaturados. Por outro lado, estas propriedades não se modificaram nas misturas com maior proporção de estearina. Este comportamento se deve à distribuição aleatória dos ácidos graxos nos triacilgliceróis após a interesterificação, que forma triacilgliceróis em proporções diferentes das existentes originalmente. Os principais triacilgliceróis nas misturas foram PPP, PPO e POO. Antes da interesterificação os ácidos graxos saturados foram encontrados principalmente nas posições sn-1,3. Mudanças significativas na composição dos ácidos graxos na posição sn-2 após a interesterificação química foram encontradas em misturas com mais de 60% de oleína de palma. A mistura e a interesterificação permitiram obter gorduras com diferentes graus de plasticidade, aumentando as possibilidades de uso das frações estearina e oleína de palma. / The challenge of the food industries for the replacement of trans fat in various products lies in the development of formulations and processes which have equivalent functionality and economic viability. The chemical interesterification of palm stearin and palm olein is an important technological option for the production of fats targeting commercial applications, without formation of trans fatty acids Palm oil contains similar amounts of saturated and unsaturated fatty acids. After fractionation two fractions are obtained: stearin (solid fraction) and olein (liquid fraction). Palm stearin and palm olein are alternatives for the production of many products, such as margarines and shortenings. The objective of this work was to modify the physical and chemical properties of mixtures of palm stearin and palm olein by using chemical interesterification. The following properties were analyzed: fatty acid and triacylglycerol compositions, regiospecific distribution of fatty acids in triacylglycerols, iodine value, softening and melting points, solid fat content, consistency and crystal microstructure. Saturated fatty acids are predominant in palm stearin (71.9%), which corresponds to 65.5% of palmitic acid. Palm olein has as its main constituent the oleic acid, which represents 45.4% of the unsaturated fatty acids. The increase of the proportion of palm olein in the mixture causes increase on the amount of unsaturated fatty acids and iodine value and decrease on the content of saturated fatty acids. After chemical interesterification, melting and softening points, consistency and solid fat content increased in the blends that had higher proportion of palm olein, as a consequence of the increase in the trisaturated triacylglycerols. On the other hand, these properties did not alter in the blends with higher proportion of palm stearin. This behavior is due to the random distribution of fatty acids in triacylglycerols after interesterification, which forms triacylglycerols in proportions that are different from those originally present. The major triacylglycerols in the blends were PPP, PPO and POO. Before interesterification the saturated fatty acids were found mainly in the sn-1,3 positions. Significant changes in the fatty acid composition in the sn-2 position after chemical interesterification were found in blends with more than 60 % of palm olein. Blending and interesterification of fats resulted in structured lipids with different degrees of plasticity, increasing the possibilities of use of stearin and olein fractions.
123

Características físico-químicas de méis de abelha (Apis mellifera L.) em diferentes condições de armazenamento. / Physicochemical characteristics of bee honeys (Apis mellifera L.) under different storage conditions.

MELO, Zilmar Fernandes Nóbrega. 06 June 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-06-06T18:24:16Z No. of bitstreams: 1 ZILMAR FERNANDES NÓBREGA MELO - DISSERTAÇÃO PPGEA 2002..pdf: 14604622 bytes, checksum: 92a403c722a2a592fbb333f263c9b64f (MD5) / Made available in DSpace on 2018-06-06T18:24:16Z (GMT). No. of bitstreams: 1 ZILMAR FERNANDES NÓBREGA MELO - DISSERTAÇÃO PPGEA 2002..pdf: 14604622 bytes, checksum: 92a403c722a2a592fbb333f263c9b64f (MD5) Previous issue date: 2002-08 / Estudou-se o armazenamento de méis de abelhas africanizadas (Apis mellifera L.) coletados no brejo e cariri do estado da Paraíba. Utilizou-se, quanto à florada, dois tipos de mel de abelha (mel de florada silvestre e mel de florada de baraúna), armazenados sob 3 diferentes condições de embalagens (El - recipiente de polietileno opaco e exposto à luz e temperatura ambiente; E2 - recipiente de polietileno exposto à temperatura ambiente e ao abrigo da luz; E3 - recipiente em vidro translúcido exposto à temperatura e luz ambiente), ao longo de 180 dias, tendo sido estes submetidos a análises físico-químicas mensalmente, com a finalidade de observar as possíveis alterações nas características físico-químicas (°Brix, Umidade, Cinzas, Hidroximetilfurfural-HMF, Açúcares redutores, Sacarose aparente, Atividade diastásica e pH), objetivando verificar a eficiência destas embalagens no índice de qualidade dos méis. As análises físico-químicas dos méis foram feitas seguindo o recomendado pela Instrução Normativa do Ministério da Agricultura e do Abastecimento (Brasil, 2000). Os valores médios encontrados, ao longo do Armazenamento, para o °Brix do mel silvestre ficaram no intervalo de variação de 78,03 a 78,42 °Brix e o da florada de baraúna de 81,31 a 81,63 °Brix e não houve diferença significativa entre as embalagens ao longo do armazenamento. Os níveis de Umidade (%) para os méis silvestres e de baraúna foram 19,48 a 20,48 % e 16,25 a 16,70 %, respectivamente. Os valores Cinzas e de Sólidos Insolúveis não apresentara diferenças significativas no tempo e/ou nas embalagens. Os níveis no índice de HMF ficaram no intervalo de variação de 4,57 a 10,17 mg/kg de mel e 1,08 a 7,12 mg/kg, no mel Silvestre e no mel de baraúna, respectivamente. Pelas análises estatísticas, verificou-se, para os dois méis, diferença significativa a 1% de probabilidade e que as médias diferem entre si. Houve para o HMF, diferença significativa entre as embalagens e a E2 foi a mais eficiente no controle do aumento deste índice nos dois méis estudados. Os valores médios de Açúcares Redutores ficaram entre 74,09 e 76,41 % no mel Sivestre e entre 62,51 e 64,80 % para o mel de baraúna. Os valores de Sacarose Aparente ficaram entre 2,18 a 3,01 % para o mel silvestre e entre 2,40 e 2,89 % no mel de baraúna. Os méis sofreram pequena variação no tempo e as embalagens não influenciaram sobre a sacarose, nos dois méis. A Atividade Diastásica (DN) no mel Sivestre ficou no intervalo de variação de 13,37 a 18,71 DN e 9,14 a 13,25 DN no mel de baraúna. As análises estatísticas para os dois méis foram significativas ao nível de 1% de probabilidade e no teste de Tukey, as médias diferiram entre si, e a embalagem E2, nos dois méis analisados, mostrou-se mais eficiente na desaceleração do índice de Diástase em relação a El e E3. Quanto ao pH, o mel Sivestre foi mais ácido (3,42 a 3,55) do que o mel de baraúna (3,85 a 4,15). Todas as amostras encontram-se dentro dos padrões exigidos pelo Ministério da Agricultura e do Abastecimento. Do resultado final, concluiu-se que houve maior eficiência na embalagem E2, que contribuiu para a desaceleração do ritmo no índice de diástase. Observou-se que o índice de acidez livre aumentou ao longo do armazenamento. / The storage of african bees honeys (Aipis mellifera L.) which were collected from slough and cariri in Paraíba state was studied. Considering the bloomed, two kinds of bee honey (wild bloomed honey and baraúna bloomed honey) were used and storaged under three different conditions of packages ( Ei - opaque polyethylene container, that was under environment light and temperature; E2 - polyethylene container that was under environment temperature but it wasn't under light environment; E3 - translucent glass container which was exposed to environment temperature and light). These honeys stayed 180 days in packages and their physiochemical characteristics were analysed monthly to observe the possible alterations of them ( 0 Brix, Humidity, Ashes, Hydroximethylfurfurol - HMF, Reducers Sugar, Apparent Saccharose, Diastasic Activity and pH) to verify the efficiency of these packages in the honeys qualities index. The physiochemical analyses of the honeys were done according to the Normative Instruction of the Agriculture and Provisioning Ministry (Brazil, 2000). During the storage time, the médium found values to the 0 Brix of the wild bloomed honey were between 78.03 and 78.42 0 Brix and the ones of the baraúna bloomed honey were between 81.31 and 81.63 0 Brix and there wasn't significant difference among the packages during the storage period. The Humidity rates (%) were between 19.48 and 20.48% to the wild honey and between 16.25 and 16.70 to the baraúna honey. There were no significant differences of the Ashes and Insoluble Solids values on their time and packages. The rates in the HMF index varied from 4.57 to 10.17 mg/Kg of honey and from 1.08 to 7.12 mg/Kg, to the wild and baraúna honeys, respectively. According to the statistics analyses, a significant difference of 1% of probability for both honeys was verified, besides the averages are different among them. To the HMF, there was a significant difference among the packages and the E2 was the most efficient to the control of the increase of this index in both studied honeys. The médium values of the Reducers Sugar were between 74.09 and 76.41% to the wild honey and they were between 62.51 and 64.80% to the baraúna honey. The Apparent Saccharose values were between 2.18 and 3.01% to the wild honey and they were between 2.40 and 2.89 to de baraúna honey. The honeys had a little time variation and the packages had no influence on the saccharose, in both honeys. The Diastasic Activity (DN) on the Wild honey varied from 13.37 to 18.71 DN and the variation of the baraúna honey was from 9.14 to 13.25 DN. The statistics analyses were significative at 1% of probability and at the Tukey test for both honeys, the averages were diferent among them and the E2 package was more efficient than the Ei and E3 to the unacceleration of the diástase index for both honeys. Analysing the pH, the wild honey was more acid (3.42 to 3.55) than the baraúna honey (3.85 to 4.15). Ali the samples are according to the Agriculture and Provision Ministry patterns. According to the final result, it's conclued that there was a bigger efficiency of the E2 package and it contributed to the rhythm unaceleration in the distasic index. It was observed that the free acidity index increased during the storage period.
124

[en] COMPARATIVE STUDY OF MICROEMULSION AND PRECIPITATION PROCEDURES ON SNO2 SYNTHESIS AND THE INFLUENCE OF CATALYSTS PREPARATION METHODS ON THE PHYSICOCHEMICAL PROPERTIES OF COMMERCIAL OXIDES / [pt] ESTUDO COMPARATIVO DE SISTEMAS DE MICROEMULSÃO E DE PRECIPITAÇÃO NA SÍNTESE DE SNO2 E DA INFLUÊNCIA DE MÉTODOS DE PREPARAÇÃO DE CATALISADORES EM PROPRIEDADES FISICO-QUÍMICAS DE ÓXIDOS COMERCIAIS

RENATO MOUTINHO DA ROCHA 07 February 2018 (has links)
[pt] Nanopartículas de dióxido de estanho foram obtidas a partir da reação de soluções aquosas de sais de estanho em sistemas de microemulsão e comparadas, em relação às suas propriedades texturais, estruturais e de condutividade elétrica, com nanopartículas do mesmo óxido obtidas pelo método convencional de precipitação. Foram realizadas alterações nos métodos utilizados a fim de se verificar a influência dos parâmetros de síntese, tais como: natureza da fase orgânica e do surfactante, tempo e temperatura de reação. Paralelamente, óxidos comerciais de titânio, alumínio e silício foram submetidos aos métodos de impregnação seca e de microemulsão. A influência desses métodos nas propriedades texturais, estruturais e no comportamento térmico desses óxidos foi estudada. As amostras obtidas foram caracterizadas por adsorção de N2, difração de raios X, espectroscopia de reflectância difusa na região do UV-visível e microscopia eletrônica de transmissão. Também foram realizadas análises de condutividade elétrica e de densidade aparente. As análises mostraram, no caso do óxido de estanho, que o método envolvendo microemulsões, apesar da grande dificuldade experimental, apresentou resultados semelhantes ao método convencional em relação ao tamanho de cristalito, à condutividade elétrica e à diferença de energia entre os orbitais HOMO-LUMO. Entretanto, o método de precipitação gerou o óxido de estanho com maior área superficial, 245 m(2)g(-1). Para os óxidos comerciais, diferenças significativas na textura das amostras foram encontradas. No caso do óxido de titânio, os resultados indicam que o método de impregnação afeta a estrutura desse óxido de forma a permitir a transformação da fase (anatásio/rutilo) em temperaturas mais baixas. / [en] Tin oxide nanoparticles have been obtained from the reaction of aqueous solutions of tin salts in microemulsion systems and compared with the same oxide nanoparticles obtained by the precipitation conventional method. Changes have been made in the methods used in order to verify the influence of synthesis parameters, such as: organic phase and surfactant nature, reaction time and temperature. In addition, titanium, aluminum and silicon commercial oxides have been subjected to dry impregnation and microemulsion methods. The influence of the method used in the textural and structural properties, and thermal behavior of these oxides have been studied. The samples have been characterized by adsorption of N2, X-ray diffraction, diffuse reflectance spectroscopy in the UVvisible range, and transmission electron microscopy. Furthermore, electrical conductivity and apparent density analysis have been performed. Despite difficult encountered in microemulsion systems experiments, tin oxide thus obtained is similar to the conventional method on crystallites size, electrical conductivity and the difference of energy between HOMO-LUMO orbitals results. However, precipitation method generated tin oxide with larger surface area, approximately 245 m(2)g(-1). For commercial oxides, significant differences on texture of the samples have been found. In the case of TiO2, the results also indicate that the dry impregnation method affects the structure so that phase transformation (anatase to rutile) occurs at lower temperatures.
125

Matériaux polymères avec hydrophilie contrôlée. Applications en ingénierie tissulaire du cartilage articulaire / Polymeric materials with controlled hydrophilic character. Applications in articular cartilage tissue engineering

Bostan, Luciana Elena 11 February 2011 (has links)
Les maladies ostéoarticulaires représentent environ 10% de l’ensemble des pathologies identifiées en France chaque année. Ces maladies inflammatoires et dégénératives des articulations sont pour la plupart consécutives au vieillissement ou à un traumatisme et évoluent vers l’usure des cartilages, d’où un handicap sévère. Comme aucun traitement ne permet la réparation totale du tissu cartilagineux, la recherche médicale développe des techniques d’ingénierie tissulaire. Ces techniques utilisent des substrats polymériques et des cellules souches qui sont « contraints » de se développer pour former du tissu cartilagineux. Cependant, ces techniques ne peuvent pas encore être utilisées à l’échelle d’une articulation complète car il n’est pas possible de reproduire ex vivo à grande échelle la structure et les propriétés mécaniques et physicochimiques du cartilage articulaire. Dans ce contexte, les travaux de cette thèse ont permis de développer des matériaux polymères capables d’être implantés à l’échelle macroscopique dans les articulations pathologiques afin de combler l’usure des cartilages. Pour se faire, de nouveaux biomatériaux - hydrogels p(HEMA) - ont été obtenus en contrôlant le caractère hydrophile des hydrogels p(HEMA) au cours de leur synthèse chimique en présence de différents co-monomères (acide acrylique, acrylamide, acrylate d'éthylène et acrylate de butyle). Partant de là, les propriétés physicochimiques, mécaniques et tribologiques de ces nouveaux hydrogels ont été optimisées afin d’obtenir des propriétés similaires à celles du cartilage articulaire sain. Ensuite, la libération contrôlée de médicaments par ces hydrogels a été étudiée afin de minimiser les risques inflammatoires lors de leur utilisation en ingénierie tissulaire du cartilage articulaire. / Osteoarticular diseases re present approximately 10% of all diseases identified in France each year. These inflammatory and degenerative joint disease are mostly consecutive with age or injuries and the wear progress of cartilage, resulting in severe disability. Because no treatment will total repair the cartilage tissue, medical research is developing techniques based on tissue engineering. These techniques use polymer substrates and stem cells that are "forced" to develop into cartilage tissue. However, these techniques cannot be used across a run articulation because Il is not possible-to replicate ex vivo a large-scale structure and the physicochemical and mechanical properties of articular cartilage. In this context, the purpose of this thesis is to develop polymer materials that can be implanted at the macroscopic level in the joints disease that will fill the wear of the cartilage. To do so, new biomaterials - hydrogels p (HEMA)- were obtained by controlling the hydrophilic nature of hydrogels p (HEMA) during their chemical synthesis in the presence of various co-monomers (acrylic acid, acrylamide, acrylate ethylene and butyl acrylate). From there, physicochemical, mechanical and tribological properties of these novel hydrogels have been optimized to obtain similar properties to those of healthy articular cartilage. Then, the controlled release of drugs from these hydrogels was studied to minimize inflammatory when used in tissue engineering of articular cartilage.
126

Couplage RMN et rayonnement synchrotron à haute température pour l’étude de fluorures fondus : application aux fluorures de zirconium / Coupling NMR with Synchrotron radiation at high temperature for the study of molten fluorides : applied to zirconium fluorides

Maksoud, Louis 14 October 2013 (has links)
Les fluorures fondus sont utilisés dans les Réacteurs à Sels Fondus tels que le réacteur non modéré, à neutrons rapides, MSFR où le sel fondu LiF-ThF4 joue le rôle du combustible et du liquide caloporteur. La formation des produits de fissions (PF) tels que les lanthanides, au cours du fonctionnement de ce réacteur, peut modifier les propriétés physicochimiques du bain fondu. Il est ainsi important de caractériser le bain fondu de point de vue structural et dynamique afin de remonter à ses propriétés. En raison des problèmes de radioactivité liés au thorium, et des conditions requises liées aux méthodes spectroscopiques utilisées, le système étudié dans ce manuscrit est le LiF-ZrF4-LaF3 (le zirconium et le lanthane étant des PF potentiels). L'approche développée dans cette thèse combine des mesures par spectroscopies RMN et EXAFS à 850 °C avec des simulations de dynamique moléculaire. Dans le bain fondu, nous avons montré la coexistence de complexes à base de zirconium et de lanthane de différentes coordinences, dont les proportions et les interactions dépendent de la composition. En fonction de la teneur en ZrF4, les espèces [ZrF7]3- majoritaires évoluent peu mais se connectent davantage via des fluors pontants. L’ajout de LaF3 au mélange stabilise la coordinence 7 autour du zirconium et tend à enrichir l’environnement du lanthane en fluors. Un ordre à moyenne portée s’établit entre les différents complexes à base de zirconium et de lanthane par l’intermédiaire des fluors pontants. La dynamique des espèces est ralentie en fonction de l’ajout de ZrF4 et LaF3. Nous avons noté un effet important sur la structure et la dynamique des espèces à partir de 10% mol. LaF3 ajouté au mélange. Les données obtenues par cette approche originale de la chimie du bain fondu dans le RSF en présence des PF, sont fondamentales pour améliorer la séparation de ces derniers et optimiser le procédé. / Molten fluorides are used in Molten Salt Reactors MSR such as the non moderated fast reactor MSFR, where the molten salt LiF-ThF4 is the fuel and the coolant. The formation of fission products (FP) such as lanthanides, during the reactor operation, possibly modifies the physicochemical properties of the melt. It is therefore important to characterize the melt from the structural and the dynamics point of view in order to determine its properties. Because of problems related to the radioactivity of thorium, as well as requirements related to spectroscopic methods, the system studied in this thesis is the LiF-ZrF4-LaF3 (zirconium and lanthanum are possible FP). The approach followed in this thesis combines measurements by NMR spectroscopy and EXAFS at 850 °C with molecular dynamics simulations. In the molten salt, we have shown the existence of zirconium and lanthanum complexes with different coordination numbers, whose proportions depend on the composition. Depending on the content of ZrF4, [ZrF7]3- species are dominant but change slightly and are further connected between each other’s via bridging fluorine. The addition of LaF3 to the mixture stabilizes the 7 coordination number around the zirconium and tends to enrich the environment of lanthanum with fluorides. A medium-range order is established between the various complexes containing zirconium and lanthanum due to bridging fluorine. Species dynamics is slower when the amount of either ZrF4 or LaF3 is higher. We noted a significant effect on the structure and dynamics of species starting 10 mol%. LaF3 added to the medium. The data obtained by this novel approach concerning the chemistry of the molten salt in MSR containing FP, are fundamental to improve the separation of these products and optimize the process.
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Propriedades físicas, químicas, nutricionais e tecnológicas de feijões (Phaseolus vulgaris L.) de diferentes grupos de cor / Physical properties, chemical, nutritional and technological beans (Phaseolus vulgaris L.) of different color groups

Pinto, Jennifer Vieira 25 August 2016 (has links)
Submitted by Erika Demachki (erikademachki@gmail.com) on 2017-02-14T16:31:16Z No. of bitstreams: 2 Dissertação - Jennifer Vieira Pinto - 2016.pdf: 3207260 bytes, checksum: 75e3617cc1ca4e537ea4eb6d34fb3ef8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Rejected by Luciana Ferreira (lucgeral@gmail.com), reason: Érika, na citação a letra "M" de mestrado é maiúscula, assim, como, o "D" de doutorado. Dissertação (Mestrado em Ciência e Tecnologia de Alimentos) - Universidade Federal de Goiás, Goiânia, 2016. on 2017-02-15T09:28:57Z (GMT) / Submitted by Erika Demachki (erikademachki@gmail.com) on 2017-02-15T15:56:43Z No. of bitstreams: 2 Dissertação - Jennifer Vieira Pinto - 2016.pdf: 3207260 bytes, checksum: 75e3617cc1ca4e537ea4eb6d34fb3ef8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2017-02-15T15:57:00Z (GMT) No. of bitstreams: 2 Dissertação - Jennifer Vieira Pinto - 2016.pdf: 3207260 bytes, checksum: 75e3617cc1ca4e537ea4eb6d34fb3ef8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-02-15T15:57:00Z (GMT). No. of bitstreams: 2 Dissertação - Jennifer Vieira Pinto - 2016.pdf: 3207260 bytes, checksum: 75e3617cc1ca4e537ea4eb6d34fb3ef8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-08-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / We aimed to characterize the physical, chemical, technological, nutritional and functional properties of beans from different color groups in order to feed the Embrapa Rice and Beans database, contributing with useful information to the scientific community and food industries. Carioca (Pérola - "PER" and BRS Estilo - "ETL"), black (BRS Esteio - "EST" and IPR Uirapuru - "IPR") and special beans (BRS Agreste - "AGR" and BRS Pitanga - "PIT") were grown in June (winter / 2014) in Santo Antônio de Goiás -GO, and analyzed for: the 100-seed weight, size, sphericity, color, moisture, water activity and density. Flours were analyzed for: granulometry, color, water absorption and solubility index, oil retention capacity, foam properties, emulsifiers, stabilizers, paste properties, kaempferol content, proximal composition, minerals, amino acid profile, protein in vitro digestibility and anti-nutritional factors. Black grains were lighter, and carioca, heavier. Grains of "PER" presented greater length and "AGR", greater sphericity; "ETL" tended to lighter grains; "PIT", "IPR" and "EST", darker. Flours of "EST" and "IPR" had greater uniformity; "ETL", "PER" and "AGR" presented lighter and more yellow flours; the "IPR" flour showed higher values of water absorption; "EST", higher values of oil absorption; the "PIT", better solubility; AGR, higher foaming (pH 2.5); the "IPR", the higher maximum viscosity. Grains of "PIT" presented higher concentration of kaempferol; "PIT" and "PER", higher protein levels; "EST" had more lipids; and "AGR", more carbohydrates. All flours had high mineral contents. Black beans showed higher levels of essential and non-essential amino acids, followed by special and carioca beans; "EST" had the lowest Essential Amino Acid Score (EAS) (1.20), and "ETL", highest EAS (1.40); "EST", lower protein digestibility; carioca and special beans, higher levels of phytic acid; "PIT" showed higher molar ratio (phytate: iron) and "AGR", higher molar ratio (phytate: zinc); "PER", lower tannin contents; "IPR", lower levels of trypsin inhibitors and "PIT", greater inhibition of α-amylase. The specialty beans presented excellent physical, chemical, technological, nutritional and functional characteristics, and can be used as ingredients of new products by the food industry. / Objetivou-se caracterizar propriedades físicas, químicas, tecnológicas, nutricionais e funcionais de feijões de diferentes grupos de cor, a fim de alimentar o banco de dados da Embrapa Arroz e Feijão, contribuindo com informações úteis à comunidade científica e indústrias de alimentos. Feijões carioca (Pérola – “PER” e BRS Estilo – “ETL”), preto (BRS Esteio – “EST” e IPR Uirapuru – “IPR”) e especial (BRS Agreste – “AGR” e BRS Pitanga – “PIT”) foram cultivados em Junho (inverno/2014), em Santo Antônio de Goiás-GO, e analisados quanto à/ao: peso de 100 grãos, tamanho, esfericidade, cor, umidade, aw e densidade. Farinhas foram analisadas quanto à/ao: granulometria, cor, índice de absorção e solubilidade em água, capacidade de retenção de óleo, propriedades espumantes, emulsificantes, estabilizantes, propriedades de pasta, teor de kaempferol, composição centesimal, minerais, perfil de aminoácidos, digestibilidade proteica in vitro, e fatores antinutricionais. Grãos pretos apresentaram-se mais leves, e carioca, mais pesados. Grãos de “PER” apresentaram maior comprimento e da cultivar “AGR”, maior esfericidade; ”ETL” tendeu a grãos mais claros; ”PIT”, “IPR” e “EST”, mais escuros. Farinhas de “EST” e “IPR” tiveram maior uniformidade; “ETL”, “PER” e “AGR” apresentaram farinhas mais claras e amareladas; farinha do “IPR” apresentou maiores valores de absorção de água; “EST”, maiores valores de absorção de óleo; a da “PIT”, melhor solubilidade; a da “AGR”, maior formação de espuma (pH 2,5); a do “IPR”, maior viscosidade máxima. Grãos da “PIT” apresentaram maior concentração de kaempferol; “PIT” e “PER”, maiores teores protéicos; “EST”, mais lipídeos; e “AGR”, mais carboidratos. Todas as farinhas tiveram altos teores de minerais. Feijões pretos apresentaram maiores teores de aminoácidos essenciais e não essenciais, seguidos dos feijões especiais e carioca; “EST” teve o menor Escore de Aminoácidos Essenciais (EAE) (1,20), e “ETL”, maior EAE (1,40); “EST”, menor digestibilidade proteica; feijões carioca e especiais, maiores teores de ácido fítico; “PIT” apresentou maior razão molar (fitato:ferro) e “AGR”, maior razão molar (fitato:zinco); “PER”, menores teores de taninos; “IPR”, menores teores de inibidores de tripsina e “PIT”, maior inibição de α-amilase. Os feijões especiais apresentaram ótimas características físicas, químicas, tecnológicas, nutricionais e funcionais, podendo ser utilizados como matéria prima na elaboração de novos produtos pela indústria alimentícia.
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Vecteurs synthétiques et approche mécano-biologique permettant d’optimiser l’utilisation des cellules souches en médecine régénérative / Synthetic vectors and mechano-biological approach to optimize the use of stem cells in regenerative medicine

Rmaidi, Assia 01 July 2019 (has links)
Une approche de la médecine régénérative du système nerveux consiste à développer des substituts biologiques avec une fonction réparatrice en utilisant des cellules souches et des biomatériaux qui peuvent être recouverts des molécules de la matrice extracellulaire. Nous avons ainsi développé des microcarriers pharmacologiquements actifs, MPA. Ce sont des microsphères (MS) polymériques à base de PLGA, biodégradables et biocompatibles, recouvertes des molécules d’adhérence qui fournissent un support en 3-dimensions aux cellules. Les microcarriers ainsi associés aux cellules souches permettent, après implantation, d’augmenter la survie et de maintenir l’état de différenciation des cellules qu’ils portent,renforçant leurs effets de réparation tissulaire. Ces MPA peuvent également libérer des facteurs de croissance encapsulés et afin d’améliorer le relargage de protéines encapsulées une nouvelle combinaison de polymère : PLGA-Poloxamer188 (P188) -PLGA a été développé dans notre laboratoire. Il a aussi été montré que les MPA de PLGA-P188-PLGA fonctionnalisées avec de la fibronectine et poly-D-lysine induisaient une meilleure prolifération de cellules souches mésenchymateuses que les MPA de PLGA.Ces cellules sont très largement utilisées en médecine régénérative car elles sont faciles à prélever, se trouvant dans la moelle osseuse, et capables de se différencier vers le lignage chondrogénique, ostéogénique et dans certaines conditions, neuronale. Nous travaillons avec une sous population de ces cellules appelées cellules MIAMI (marrow isolated adult multilineage inducible) qui s’engagent vers une différenciation en cellule neuronale après un traitement avec 2 facteurs de croissance (EGF/ bFGF) et sur un support matriciel de laminine. Dernièrement, il a été mis en évidence que les propriétés physicochimiques des supports polymériques régissent également le comportement des cellules souches(adhésion, survie et différenciation). L’objectif de cette étude est d’étudier l’effet des propriétés physicochimiques et mécaniques des surfaces i) des MS sur l’adsorption de laminine et poly-D-lysine et ii) des MPA sur l’adhérence et la différenciation neuronale des cellules MIAMI. Nous avons montré que la présence du bloc hydrophile « poloxamère 188 » dans la composition du polymère PLGA-P188-PLGAdiminue l’adsorption de molécules d’adhérence en formant une couche sur ces surfaces. Sur les MPA de PLGA, les molécules d’adhérence s’adsorbent bien quelle que soit la charge globale des molécules. Cesdeux MPA ont une charge globale positive et permettent l’attachement de cellules à leur surface. Cependant, l’adhérence à court terme de cellules est plus forte sur les MPA de PLGA comparé aux MPA de PLGA-P188-PLGA mais à la longue les cellules finissent par adhérer aux deux supports. Le PLGAP188-PLGA présente une forte énergie libre de surface et ces MPA présentent une surface moins rigide que les MPA de PLGA. Nos résultats suggèrent que ces caractéristiques de surface permettent aux cellules d’adhérer malgré la faible quantité de laminine sur ces supports. A long terme les cellules présentent le même comportement quel que soit le type du support. Elles se différencient en cellule de type neuronal exprimant des marqueurs de neurone mature comme le neurofilament et nous trouvons le même nombre de cellules adhérées à leur surface. En outre, nous avons montré que les cellules sont capables de sécréter de la même manière des molécules de la matrice extracellulaire sur les deux types de MPA expliquant probablement la similitude de comportement à long terme. / An approach to regenerative nervous system medicine is to develop biological substitutes with restorative function using stem cells and biomaterials that can be coated with extracellular matrix molecules. We have developed pharmacologically active microcarriers, PAMs. These are PLGA based, biodegradable and biocompatible polymeric microspheres (MS) coated with adhesion molecules that provide 3-dimensional support for cells. The microcarriers thus associated with the stem cells make it possible, after implantation, to increase the survival and maintain the state of differentiation of the cells they carry, reinforcing their tissue repair effects. These PAMs can also release encapsulated growth factors and to enhance the release of encapsulated proteins a new polymer combination: PLGA-Poloxamer188 (P188) -PLGA has been developed in our laboratory. It has also been shown that PLGA-P188-PLGA PAMs functionalized with fibronectin and poly-Dlysineinduce better proliferation of mesenchymal stem cells than PLGA PAMs. These cells are very widely used in regenerative medicine because they are easy to collect, found in the bone marrow, and able to differentiate towards the chondrogenic lineage, osteogenic and under certain conditions,neuronal. We are working with a subpopulation of these cells called MIAMI cells (marrow isolated adult multilineage inducible) that engage in neuronal cell differentiation after treatment with 2growth factors (EGF / bFGF) and on a laminin matrix support. Recently, it has been demonstrated that the physicochemical properties of polymeric supports also regulate the behavior of stem cells (adhesion, survival and differentiation). The objective of this study is to study the effect of physicochemical and mechanical properties of surfaces i) MS on laminin and poly-D-lysineadsorption and ii) PAMs on adhesion and neuronal differentiation of MIAMI cells. We have shown that the presence of the hydrophilic "poloxamer 188" block in the PLGA-P188-PLGA polymer composition decreases the adsorption of adhesion molecules by forming a layer on these surfaces.On PLGA PAMs, the adhesion molecules adsorb well regardless of the overall charge of the molecules. These two PAMs have a positive overall charge and allow the attachment of cells to their surface. However, in short-term cell adhesion is stronger on PLGA PAMs compared to PLGA-P188-PLGA PAMs, but in the long-term the cells eventually adhere to both supports. PLGA-P188-PLGAhas a high free surface energy and these PAMs have a less rigid surface than PLGA PAMs. Our results suggest that these surface characteristics allow cells to adhere despite the low amount of laminin on these supports. In the long-term the cells exhibit the same behavior whatever the type of PAMs. They differentiate into neuronal cells expressing mature neuron markers such as the neurofilament-M and we find the same number of cells adhered to their surface. Furthermore, we have shown that cells are able to secrete extracellular matrix molecules in the same way on both types of PAMs, probably explaining the similarity of the behavior in long-term.
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Photoluminescence et cristallochimie des polyphosphates de formule Na1-xAgxM(PO3)4 (M : la, Y) à l’état cristallisé ou vitreux / Photoluminescence and crystallochemistry of crystallized or vitreous polyphosphates Na1-x AgxM(PO3)4 (M : la, Y)

El Masloumi, Mohamed 15 December 2008 (has links)
Ce travail s’inscrit dans le cadre d’une étude systématique des propriétés physico-chimiques de polyphosphates à l’argent permettant d’avancer sur de nouvelles voies pour les dispositifs tels que l’éclairage, les lasers accordables dans le visible, la radiophotoluminescence. L'objectif de ce travail vise la compréhension des mécanismes de luminescence de l’ion Ag+ dans les composés Na1-xAgxLn(PO3)4 (Ln = La et Y) dont la structure a été parfaitement déterminée. La luminescence des monocristaux provient des ions Ag+, dans des sites isolés et proches de lacunes positives (Ag2+) résultant de la photosensibilité aux UV pour les cristaux au lanthane. La luminescence des verres Na1-xAgxLa(PO3)4 (seuls vitrifiables) a été élucidée grâce à une étude après irradiation et à celle des verres Na2-xAgxZnP2O7. Elle est due aussi aux ions Ag+ dans des sites isolés. / This work focuses on keeping with the general pattern of investigations of physical-chemical properties of silver-polyphosphates to find new ways for devices such as lighting, visible range laser applications and radiophotoluminescence. The goal of this study aims at understanding the processes of Ag+ luminescence in Na1-xAgxLn(PO3)4 (Ln = La et Y) compounds which structure has been completely determinated. The luminescence of the single crystals is induced by Ag+ ions in isolated sites and close to hole centers (Ag2+) resulting in UV photosensitivity for the lanthanum crystals. The photoluminescence of the Na1-xAgxLa(PO3)4 glasses (glass-forming only) has been resolved owing to UV irradiation investigations and comparison with the luminescence of Na2-xAgxZnP2O7 glass. Both are also due to Ag+ ions in isolated sites.
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Interesterificação química e enzimática de misturas de estearina de palma, óleo de coco e óleo de canola para formulação de margarinas com baixa concentração de isômeros trans / Chemical and enzymatic interesterification of palm stearin mixtures of coconut oil and canola oil margarine formulation with a low concentration of trans isomers

Soares, Fabiana Andréia Schäfer De Martini 03 July 2014 (has links)
O consumidor está cada vez mais consciente da relação entre dieta e doença, que tem impulsionado as pesquisas sobre alimentos funcionais e seus efeitos sobre o corpo. O papel dos óleos e gorduras na nutrição humana tem sido intensamente estudado e discutido por décadas. Tem sido enfatizada a importância da ingestão de ômega-3, ômega-6 e ômega-9 ácidos graxos redução de ácidos graxos saturados e, mais recentemente, controle da ingestão de ácidos graxos trans. Através da mistura e interesterificação química e enzimática de óleos e gorduras, gorduras trans-livre pode ser produzido. Mistura de gordura, foram formuladas por misturas ternárias de estearina de palma, uma gordura láurica (óleo de coco ou óleo de palmiste) e um óleo poliinsaturado (óleo de canola ou azeite de oliva) em diferentes proporções que foram interesterificadas. Neste trabalho, foram produzidos lipídios estruturados por interesterificação química e enzimática. A interesterificação química foi realizada nas seguintes condições: a 88 °C, 60 minutos de reação, 0,4% de catalisador metóxido de sódio, sob agitação e vácuo. A interesterificação enzimática, sendo realizada com duas lipases comerciais Thermomyces lanuginosa e Rhizomucor miehei, com seletividade sn-1,3. A interesterificação enzimática por batelada foi realizado seguindo um planejamento matriz central compósito rotativo em função da temperatura e da composição do meio, estearina de palma, óleo de palmiste e azeite de oliva e catalisado pelas lipases comerciais. O decréscimo do conteúdo de gordura sólida foi observado a 10 e 35 °C após a interesterificação. O biorreator contínuo foi operado nas seguintes condições: mistura de estearina de palma, óleo de palmiste, azeite de oliva (45:30:25), 10 gr de biocatalisador, 65 °C, com tempo de residência de 7 min e por 226 h para Thermomyces lanuginosa e 188 h para Rhizomucor miehei. A atividade do biocatalisador foi avaliada em termos da diminuição do conteúdo de gordura sólida a 35 °C, o qual é um parâmetro chave na produção de margarinas. O perfil de inativação do biocatalisador pode ser bem descrita pelo modelo de desativação de primeira ordem: meia-vida de 88 e 60 h foram estimados quando Thermomyces lanuginosa e Rhizomucor miehei, respectivamente, foram utilizados. Os óleos puros, as misturas originais e interesterificadas foram avaliados quanto à composição de ácidos graxos e triacilgliceróis, distribuição regioespecífica dos ácidos graxos nos triacilgliceróis, ponto de fusão e amolecimento, consistência, conteúdo de gordura sólida, comportamento de fusão e cristalização, estabilidade oxidativa, estrutura cristalina e polimorfismo. A interesterificação química e enzimática promoveram diminuição de triacilgliceróis trissaturados e triinsaturados e aumento dos monossaturados-diinsaturados e dissaturados-monoinsaturados, o que resultou no respectivo decréscimo dos pontos de fusão e amolecimento, consistência e conteúdo de gordura sólida, aumentando a plasticidade das gorduras. As curvas de fusão e cristalização das misturas foram modificadas pela alteração da composição dos triacilgliceróis pela interesterificação química e enzimática. Estabilidade térmica e a temperatura de oxidação da estearina de palma, óleo de coco e óleo de canola e suas misturas foram dependente da composição de ácidos graxos e independente da interesterificação química. Os resultados mostram que a interesterificação química e enzimática oferecem uma ferramenta útil para a concepção de gorduras com sintonizáveis propriedades físico-químicas, melhorando em relação a esse das gorduras de partida. / The consumer is becoming more aware of the relationship between diet and disease, which has driven the research on functional foods and their effects on the body. The role of fats and oils in human nutrition has been intensively studied and discussed for decades. It has been emphasized the importance of intake of omega-3, omega-6 and omega-9 fatty acids, reduction of saturated fatty acids and, more recently, control of intake of trans fatty acids. Through the blend and interesterification of oils and fats, trans-free fats can be produced. Fat blends, formulated by ternary blends of palm stearin, lauric fat (coconut oil and palm kernel oil) and polyunsaturated oils (canola oil and olive oil) were done in different ratios. In this work, were produced by chemical and enzymatic interesterification. Chemical interesterification was performed under the following conditions: at 88°C, 60 minutes reaction times, 0.4% sodium methoxide, under agitation and vacuum. For enzymatic interesterification being carried out with two commercial lipases Thermomyces lanuginosa e Rhizomucor miehei, with selectivity sn-1,3. Batch enzymatic interesterification were performed, following central composite rotatable designs (CCRDs) as a function temperature and media of palm stearin, palm kernel oil and olive oil formulation and catalyzed by a commercial immobilized lipase. A decrease in all SFC values of the blends at 10 °C and 35°C was observed upon interesterification. The bioreactor operated continuously: mixture of palm stearin, palm kernel oil and olive oil (45:30:25, wt %), at 65 °C, at a residence time of 7 min and for 226 h to Thermomyces lanuginosa and 188 h to Rhizomucor miehei.. Biocatalyst activity was evaluated in terms of the decrease of the solid fat content at 35 °C of the blends, which is a key parameter in margarine manufacture. The inactivation profile of the biocatalyst could be well described by the first-order deactivation model: Half-lives of 88 and 60 h were estimated when Thermomyces lanuginose and Rhizomucor miehei, respectively, were used. Pure oil, the original and interesterified blends were examined for fatty acids and triacylglycerols composition, regiospecific distribution of fatty acids in triacylglycerols, melting and softening points, consistency, solid fat content, thermal behavior, oxidation stability, crystalline microstructure and polymorphism. Chemical and enzymatic interesterification caused reduction of trisaturated and triunsaturated and increase in monosaturated-diunsaturated and disaturated-monounsaturated, lowering the initial melting and softening points, consistency and solid fat content, increasing plasticity of fats. Melting and crystallization curves were significantly modified by changing the composition of triacylglycerols by chemical and enzymatic interesterification. The thermal stability and oxidation temperature of palm stearin, coconut oil and canola oil and their blends were dependent on fatty acid composition and independent on chemical interesterification. The results show that the chemical and enzymatic interesterification provides a useful tool to design fats with tunable physicochemical properties, improved compared to that of the starting fats.

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