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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.
231

Pharmaceutical Nanocomposites : Structure–Mobility–Functionality Relationships in the Amorphous State

Hellrup, Joel January 2016 (has links)
Amorphous materials are found in pharmaceutical formulations both as excipients and active ingredients. Indeed, these formulations are becoming an essential strategy for incorporating drugs into well-performing solid dosage forms. However, there is an unmet need of better understanding of the microstructure and component interactions in amorphous formulations to be able to design materials with improved functionalities. The aim of this thesis is to give deepened knowledge about structure-mobility-functionality relationships in amorphous for-mulations by studying composites produced from sugars and filler particles. The structure, the mobility, and physical stability of the composite materials were studied using calorimetry, X-ray diffraction, microscopy, spectroscopy, and molecular dynamics simulations. Further, the moisture sorption of the composites was determined with dynamic vapor sorption. The compression mechanics of the composites was evaluated with compression analysis. It was demonstrated that fillers change the overall properties of the amorphous material. Specifically, the physical stability of the composite was by far improved compared to the amorphous sugar alone. This effect was pronounced for formulations with 60 wt% filler content or more. Amorphous lactose that normally recrystallizes within a few minutes upon humidity exposure, could withstand recrystallization for several months at 60% RH in composites with 80 wt% cellulose nanocrystals (CNC) or sodium montmorillonite (Na-MMT). The increased physical stability of the amorphous sugars was related to intra-particle confinement in extra-particle voids formed by the fillers and to immobilization of the amorphous phase at the surface of the fillers. Also, the composite formation led to increased particle hardness for the lactose/CNC and the lactose/Na-MMT nanocomposites. The largest effect on particle hardness was seen with 40-60 wt% nanofiller and could be related to skeleton formation of the nanofillers within the composite particles. The hygroscopicity for the lactose/Na-MMT nanocomposites decreased as much as 47% compared to ideal simple mixtures of the neat components. The nanofillers did not influence the water sorption capacity in the amorphous domains; however, lactose (intercalated into Na-MMT) interacted with the sodium ions in the interlayer space which led to the lowered hygroscopicity of this phase. The thesis advanced the knowledge of the microstructure of amorphous pharmaceutical com-posites and its relationship with pharmaceutical functionalities. It also presented new approaches for stabilizing the amorphous state by using fillers. The concept illustrated here might be used to understand similar phenomena of stabilization of amorphous formulations.
232

Photodegradation study of 3,5-diamino-6-chloro- N-(2-(methylamino)ethyl)pyrazine-2-carboxamide using preparative SFC and LC-MS

Sillén, Sara January 2016 (has links)
In this project the photodegradation of 3,5-diamino-6-chloro-N-(2-(methylamino)ethyl)pyrazine-2-carboxamide was studied. A hypothetical degradation pattern for the compound was proposed and the aim of the project was to study the formed secondary photodegradants and to, if possible, structure elucidate some of these compounds. In order to do this, the parent compound was photodegraded in two steps, where a primary photodegradant was isolated using semi-preparative supercritical fluid chromatography (SFC) and then further degraded into the secondary photodegradants. The photodegradation was first carried out in aqueous solution, where the parent compound was irradiated in UV-A light of 300-400 nm. This resulted in a primary photodegradant with a molecular ion of m/z = 227, where the chloride in position 6 of the pyrazine group had been replaced by a hydroxyl group. During the large scale photodegradation, prior to the preparative purification, the yield of primary photodegradant was very low due to the photodegradation being dependent on both sample volume and concentration and due to the primary photodegradant also being unstable in aqueous solution at room temperature. Due to the above mentioned difficulties the parent compound was photodegraded in methanol instead of water in order to avoid the freeze-drying process where a lot of the primary photodegradant was lost. This resulted in a primary photodegradant with a molecular ion of m/z = 241, where the chloride had been replaced by a methoxy group instead of a hydroxyl group. This compound was more stable which allowed workup by rotary evaporation, instead of freeze-drying, before the preparative purification. This primary photodegradant was isolated using semi-preparative SFC on a Viridis® BEH Prep OBD TM column (250 x 30 mm, 5 µm) and a Luna HILIC column (250 x 30 mm, 5 µm) with MeOH/NH3 100/1 v/v as organic modifier. About 1.2 mg material was isolated and further photodegradation tests in ordinary water and 18O-water were conducted. Some secondary photodegradants were observed in LC-MS analyses, and their element compositions were proposed by accurate mass results. Fundamental structures for these compounds were proposed. Further structural investigational analyses are needed for confirmation in the future.
233

Etude des transferts d'arômes encapsulés dans une matrice alimentaire type génoise / Study of encapsulated flavours transfers in food matrix like sponge cake

Madene, Atmane 14 November 2006 (has links)
Ces travaux portent sur l’étude du transfert de l’arôme viennoiserie encapsulé dans une matrice constituée du mélange gomme acacia – maltodextrines et incorporé dans une génoise emballée (plastiques et papier), dans des conditions contrôlées de stockage (humidité relative et température). Le procédé d’encapsulation utilisé dans cette étude est la lyophilisation. Les propriétés physicochimiques des molécules volatiles influencent leur rétention. Ainsi, les molécules hydrophobes à haut poids moléculaire sont mieux conservées dans ce système. L’incorporation de capsules d’arômes dans les génoises influence leurs propriétés physiques (la couleur et la texture) et favorise la formation d’une croûte pouvant jouer un rôle barrière sur les transferts d’arômes. Au cours du stockage des génoises emballées, l’apport positif de l’encapsulation sur la rétention des arômes a été révélé. Le type d’emballage peut influencer la perte en composés d’arôme dans l’espace de tête génoise – emballage. Ainsi, les emballages plastiques offrent une meilleure conservation des molécules volatiles par rapport aux papiers traités / This study deals with transfer of viennoiserie aroma encapsulated in a acacia gum - maltodextrines matrix and incorporated in a packaged sponge cake (plastic and treated-paper), under controlled storage conditions (temperature and relative humidity). The process of encapsulation used in this work is freeze-drying. The physicochemical properties of the volatiles molecules influence their retention in the matrix. Thus, the hydrophobic molecules with high molecular weight are more retained. The incorporation of capsules in the sponge cake matrix influences the physical properties of food matrix (color and texture) and supports the formation of a crust which acts as a barrier in the flavour transfer. It was noted that encapsulation contributed in retaining flavour compounds during the storage of packaged sponge cake. Also, the type of packaging can influence the loss of flavour in the headspace between sponge cake and packaging. Indeed, plastic packaging offers a better conservation of volatiles molecules compared to treated-papers
234

Amélioration de la stabilité biologique de bactéries lactiques et bifidobactéries lyophilisées et caractérisation des réponses physiologiques associées / Improvement of biological stability of freeze-dried lactic acid bacteria and bifidobacteria and characterization of associated physiological responses

Louesdon, Séverine 28 March 2013 (has links)
La production inductrielle de ferments nécessite une étape de stabilisation qui affecte la qualité des cellules. Ce phénomène étroitement lié à l’espèce, voire à la souche bactérienne considérée, dépend également des conditions mises en œuvre lors de la conduite du procédé de production. Dans ce contexte, ce travail de thèse vise à améliorer les performances de Lactobacillus buchneri R1102 et Bifidobacteium longum R0175 à la lyophilisation et au stockage, et à identifier les réponses physiologiques associées.Dans une première partie, l’effet du temps de récolte sur les caractéristiques membranaires et les performances industrielles de Lb. Buchneri R1102 et B. lolngum R0175 a été anlysé. Une récolte en phase stationnaire conduit à une meilleure tolérance au cours de la congélation pour B. longum R0175 mais ne permet pas de maintenir une activité acidifiante élevée pour Lb. Buchneri R1102. Ces résultats sont reliés à une rigidificatioin de la membrane et à une augmentation de la proportion en acides gras saturés et cycliques en phase stationnaire de croissance.Dans une deuxième étape, les cellules de Lb. Buchneri R1102 ont été soumises à différentes conditions de stress osmotique. Un stress osmotique avec du KCl 0.1 M augmente la survie au cours de la lyophilisation mais ne modifie les caractéristiques membranaires des cellules. Un ajout de KCl 0.6 M en début de fermentation améliore la survie au cours du stockage à l’état lyophilisé. Ce phénomène est expliqué par une rigidification de la membrane lié à une augmentation de la concentration en acides gras cycliques et à une accumulation de bétaïne intracellulaire.Dans une troisème partie, l’effet de différentes atmosphères de culture sur l’état physiologique et les performances de Lb. Buchneri R1102 et B. longum R0175 a été étudié.Pour Lb. Buchneri R1102, l’apport d’air accélère significativement la croissance et la concentration bactérienne (air à 1.2 vvm) en fluidifiant les membranes cellulaires et en orientant le flux métabolique vers la production d’acétate. A l’inverse, l’apport d’azote ou d’un mélange de gaz N2H2 allonge les fermentations en diminuant le potentiel d’oxydoréduction. Enfin, l’apport des gaz air, N2 et N2H2 dégrade l’activité acidifiante de Lb. Buchneri R1102 mais augmente sa survie au cours du stockage, en lien avec des modifications de composition an acides gras et de synthèse protéique. Pour B. longum R0175, une concentration cellulaire plus élevée est obtenue lorsqu’un bullage N2 ou N2CO2 est effectué en début de culture. L’activité acidifiante des ferments est préservée au cours du procédé pour toutes les conditions testées, en lien avec une augmentation de la proportion d’acides gras insaturés et cycliques, mais sans variation de fluidité membranaire.Enfin, une meilleure survie cellulaire est obtenue lorsque les cellules sont cultivées avec du N2CO2 pendant toute la fermentation.Ce travail se conclut par la validation, à l’échelle pilote, des conditions conduisant à une amélioration de la stabilité biologique des ferments lyophilisés, tout en préservant les performances des fermentations. / Industrial starter’s production requires a stabilization step that affects the quality of the cells. This phenomenon is closely linked to the used species and strains, and depends on the procedures applied during the production process. In this context, this thesis aims at improving the performances of Lactobacillus buchneri R1102 and Bifidobacterium longum R0175 during freeze-drying and storage, and to identify the corresponding physiological responses.In the first part of this work, the effect of the harvesting time on membrane characteristics and industrial performances of Lb. buchneri R1102 and B. longum R0175 has been analyzed. Harvesting the cells in stationary phase led to a better tolerance during freezing of B. longum R0175 but did not allow the maintenance of elevated acidification activity for Lb. buchneri R1102. These results have been related to a rigidification of the membrane and to an increase of the proportion of saturated and cyclic fatty acids in cellular membranes of cells recovered in stationary growth phase.In a second step, cells of Lb. buchneri R1102 have been submitted to different conditions of osmotic stress in order to improve their performances. An osmotic stress with 0.1 M KCl increased the cells survival during freeze-drying, without changing their membrane characteristics. In addition, adding 0.6 M KCl in the beginning of the fermentation improved the survival during storage on freeze-dried form. This phenomenon was explained by a rigidification of the membrane that was linked to an increase of cyclic fatty acids content and intracellular betaine concentration.The third part was devoted to the study of the effect of various gaseous atmospheres during the cultures, on the physiological state and the performances of Lb. buchneri R1102 and B. longum R0175. For Lb. buchneri R1102, aeration (air at 1.2 vvm) significantly accelerated the growth and the final cell concentration by increasing membrane fluidity and by directing metabolic flux towards acetate production. Conversely, adding nitrogen or the gas mixture N2H2 delayed the fermentations by decreasing redox potential. Lastly, injecting different gases (air, N2, N2H2) decreased acidification activity Lb. buchneri R1102 but increased its survival during storage, as a result of modifications of fatty acids composition and proteins synthesis. For B. longum R0175, a higher cell concentration was obtained when the culture medium was bubbled with N2 or N2CO2 at the beginning of the fermentation. In addition, acidification activity of these starters was well maintained for all tested conditions, which was linked to an increase of unsaturated and cyclic fatty acids proportion, but without any change in membrane fluidity. Lastly, a better cell survival was obtained for cells grown with N2CO2 all along the fermentation.Finally, this work is concluded finish with the validation, at pilot scale, of the conditions leading to an improvement of the biological stability of freeze-dried starters, while maintaining their performances during fermentation.
235

Poromechanical behavior of cement-based materials subjected to freeze-thaw actions with salts : modeling and experiments / Comportement poromécanique des matériaux cimentaires soumis au gel-dégel en présence de sels : modélisation et expérimentation

Zeng, Qiang 30 November 2011 (has links)
Les matériaux cimentaires peuvent se détériorer grandement lorsqu'ils sont soumis à des cycles de gel/dégel avec ou sans sels de déverglaçage. Ceci peut porter atteinte à la durabilité à long terme des bétons/mortiers dans les régions aux hivers froids. Laissant de côté les processus d'endommagement et de rupture mécanique à l'oeuvre dans de tels problèmes, ce mémoire de thèse est consacré aux phénomènes physiques et thermo-mécaniques accompagnant la solidification de l'eau dans des solides poreux cohésifs, avec une attention particulière aux «propriétés matériau» issues de l'hydratation du ciment et de l'évolution de la microstructure. Ce travail reprend la poromécanique des milieux poreux partiellement gelés telle que développée par Olivier Coussy, tout en lui adjoignant une analyse de l'effet de la fin de la surfusion (en volume, hors contribution capillaire) et de la présence de sels dans le liquide saturant l'espace poreux. Nous avons mesuré la température de fin de surfusion en fonction de la concentration en sel. Ceci nous permet ensuite de calculer l'angle de contact entre la glace et les parois des pores dans le cadre classique de la nucléation hétérogène : on trouve que cet angle diminue avec la concentration en sel. Nous montrons que la dilatation instantanée consécutive à la fin de la surfusion dépend de la structure poreuse puisque cette dernière détermine la teneur en glace dans l'espace poreux. À l'aide de la distribution de tailles de pores estimée par porosimétrie par intrusion de mercure, nous estimons le degré de saturation en glace en fonction de la température et de la concentration initiale en sel via la relation de Gibbs-Thomson. Nous avons mesuré la déformation d'échantilllons de pâte de ciment saturées. L'analyse poromécanique montre que la déformation dépend de la concentration initiale en sel et de la structure poreuse des pâtes de ciment. En utilisant la même approche expérimentale sur des pâtes de ciment sèches, nous trouvons que la porosité (avec ou sans vide d'air entraîné) influence significativement le coefficient d'expansion thermique du matériau. En ce qui concerne les pâtes de ciment saturées, les mesures expérimentales et l'approche poromécanique en condition drainée ou non-drainée montrent que le degré de saturation initiale en liquide des vides d'air entraîné a un impact important sur la déformation de l'échantillon avec la température / When subject to freezing/thawing cycles with or without deicing salt, cement-based materials can suffer severe damage, which raises the long term sustainability problem of concrete/mortar in cold regions. Leaving aside the precise fracture mechanics and damage processes in this kind of problem, this PhD deals with the physical and thermomechanical phenomena undergone by cohesive porous solids under freezing, with particular attention to the material properties arising from cement hydration and microstructure development. The present work revisits the poromechanics of freezing porous materials developed by Olivier Coussy. This gives the opportunity to add the effect of the bulk supercooling and of salt in the liquid saturating the porous space.We measured the relation between depressed temperature at the end of bulk supercooling and salt concentration. We then obtained that the contact angle between ice and pore wall by heterogeneous nucleation decreases as salt concentration increases. We showed that the instantaneous dilation at the end of bulk supercooling is related to the pore structure because the latter determines the in-pore ice content. Using the pore size distribution measured by mercury intrusion porosimetry, we estimated the ice saturation degree with temperature and NaCl solution at different concentration through the Gibbs-Thomson equation. We measured the deformation of saturated cement pastes. The poromechanical analyses show that the strains depend on the initial salt concentration and pore structure of our cement pastes. By the same experimental approach on dried cement pastes, we concluded that the porosity (with or without air voids) has significant influence on the thermal expansion coefficient of our cement pastes. We also performed measurements on the deformation of saturated air entrained cement pastes. The results obtained by both experiments and poromechanical analyses under drained and undrained conditions showed that the initial saturation degree in air-voids has significant influence on the deformation curves with temperature
236

Produtos derivados do camu-camu: efeito da secagem sobre elagitaninos e flavonoides, atividades antioxidante e antimicrobiana / Camu-camu ingredients: effect of drying on ellagitannins and flavonoids, and their antioxidant and antimicrobial activities.

Fujita, Alice 20 August 2015 (has links)
O camu-camu (Myrciaria dubia Mc. Vaugh) tem demonstrado ser um fruto promissor devido ao potencial funcional, principalmente pelo alto teor de vitamina C e compostos fenólicos, em especial elagitaninos. Este trabalho teve como objetivo avaliar os efeitos sobre os compostos fenólicos dos processos de secagem de polpa comercial de camu-camu, por leito de jorro e atomização (spray-drying), em diferentes temperaturas e concentrações de agentes carreadores, comparando-os com os do processo de liofilização. Os pós obtidos foram comparados em relação ao teor total de compostos fenólicos, ácido ascórbico e proantocianidinas. Além disso, avaliou-se o potencial benéfico à saúde através da determinação da capacidade antioxidante in vitro , atividade antimicrobiana e inibição das enzimas α-amilase, α-glicosidase e enzima conversora da angiotensina (ECA). Avaliou-se também proteção e regeneração celulares em modelo de planárias (Dugesia trigrina). Complementarmente, os pós de camu-camu foram adicionados em leite de soja, que foram fermentados com bactérias produtoras de ácido láctico (L. helveticus ATCC 12046 e L. plantarum NCDO 1193), para verificar sua funcionalidade quando incorporados como ingredientes em alimentos funcionais. Os resultados mostraram que a secagem da polpa acarretou em perdas significativas de compostos bioativos, na ordem ácido ascórbico>fenólicos totais> proantocianidinas, e spray-drying>leito de jorro>liofilização. Os compostos fenólicos detectados nos pós de camu-camu foram elagitaninos, ácido elágico, derivados de quercetina, ácido siríngico e miricetina, por LC-TOF-MS. A liofilização foi a melhor técnica de secagem para a preservação dos compostos fenólicos, e também da capacidade antioxidante e de inibição enzimática. Além disso, os pós liofilizados e atomizado (contendo 6% goma arábica a 120 °C) foram mais efetivos contra Staphylococcus aureus que a ampicilina. Os extratos desses pós demostraram potencial para proteção celular e rejuvenescimento no modelo de planárias. E por último, o leite de soja enriquecido com o pó de camu-camu resultou em um produto com maior teor de fenólicos, alta capacidade antioxidante e propriedades anti-hiperglicêmica e anti-hipertensiva. Portanto, os pós de camu-camu são ricos em compostos fenólicos e tem potencial para serem acrescentados como ingredientes em alimentos para o controle dos estágios iniciais de diabetes tipo 2 e complicações associadas. / Camu-camu (Myrciaria dubia Mc. Vaugh) has demonstrated promising perspectives as a functional food, mainly due to high vitamin C and phenolic compounds contents, in particular ellagitannins. This study aimed to evaluate the effect of different drying processes (spouted bed drying, spray-drying) at selected temperatures and carrier concentrations, comparing to freeze-drying, on the contents and composition of phenolic compounds. The pulp powders were compared in relation to phenolic profiles, ascorbic acid and proanthocyanidins contents. Further, functional health potential was evaluated such as in vitro antioxidant capacity, antimicrobial activity and inhibition of α-amylase, α-glucosidase and angiotensin converting enzyme (ACE). It was also investigated cellular protection and regeneration in planaria (Dugesia trigrina) model. Additionally, camu-camu powders were added into soymilk and were fermented by lactic acid bacteria (L. helveticus ATCC 12046 and L. plantarum NCDO 1193) to verify their functionality as a functional food ingredient. The results showed that drying of the pulp led to significant losses of bioactive compounds, in the order ascorbic acid>total phenolics>proanthocyanidins, and spray-drying>spouted bed drying>freeze-drying. Phenolic compounds, such as ellagitannins, ellagic acid, quercetin derivatives, syringic acid and myricetin were detected in camu-camu by LC-TOF-MS. The freeze-drying was the best technique to preserve phenolic compounds, and also antioxidant capacity and enzyme inhibition. Besides that, freeze-dried and spray-dried (6% arabic gum at 120 °C) powders were more effective against Staphylococcus aureus than ampicillin. The extracts of those powders have desmonstrated potential to cellular protection and rejuvenation in planaria model. Finally, soymilk enriched with camu-camu powders resulted in more phenolic contents, high antioxidant capacity and anti-hyperglycemia and anti-hipertension properties product. To sum up, camu-camu powder is rich in phenolic bioactive profiles has potential as part of dietary strategies in the management of early stages of type 2 diabetes and associated complications.
237

Otimização da liofilização do pericárdio bovino com o auxílio de ferramentas matemáticas / Freeze-drying optimization of bovine pericardium by mathematical modeling

Borgognoni, Camila Figueiredo 01 October 2009 (has links)
A liofilização é um método de conservação utilizado para a obtenção de produtos desidratados de alta qualidade. É um processo que requer tempo e energia, podendo levar dias para terminar se o ciclo de liofilização não for otimizado. O objetivo da otimização do processo de liofilização é minimizar o consumo de energia e reduzir o tempo de processo, sem que ocorra a perda na qualidade do produto liofilizado. A utilização de modelos matemáticos que predizem o comportamento do produto durante a liofilização pode reduzir drasticamente o número de experimentos, além de determinar variáveis importantes que não podem ser medidas experimentalmente. Tecidos biológicos são produtos sensíveis que se submetidos à altas temperaturas podem sofrer alterações irreversíveis. O estudo da liofilização do pericárdio bovino tem como objetivo sua conservação, facilitando sua manipulação e armazenamento. O objetivo deste projeto foi o uso da teoria fenomenológica que envolve a liofilização, com a utilização de parâmetros essenciais determinados por experimentos de laboratório, para guiar o desenvolvimento de um modelo matemático capaz de descrever a dinâmica do processo de liofilização do pericárdio bovino para, através de seu estudo e da análise das características do produto liofilizado, alcançar a validação do processo. O estudo do congelamento na liofilização do pericárdio bovino foi feito, determinando-se os tempos de processo e o conteúdo de umidade residual do produto seco. A modelagem matemática do processo foi apresentada a partir da determinação de taxas de sublimação por microscopia óptica acoplada à liofilização, sob diferentes pressões de câmara e taxas de aquecimento de placa. Os produtos liofilizados foram avaliados quanto à manutenção de suas propriedades físicas. Os resultados mostraram que o congelamento lento com tratamento térmico apresentou curto tempo de liofilização e baixo valor de umidade residual do produto final. O modelo matemático demonstrou a liofilização do pericárdio bovino e o produto não apresentou alterações em suas propriedades físicas após o processo. Sendo assim, validou-se a técnica de microscopia óptica acoplada à liofilização na determinação da taxa de sublimação durante a liofilização do pericárdio bovino e validou-se o processo através da modelagem matemática. / Freeze-drying is a method of preservation that provides high-quality dehydrated products. It is a process that requires time and energy and it may take days to finish. Freeze-drying optimization is used to minimize the process time keeping the high quality of the product. Mathematical models that predict the behavior of products during freeze-drying can drastically reduce the number of experiments and determine variables in a study that could not be experimentally measured. Biological tissues are sensitive to heat and might be irreversibly modified. The study of bovine pericardium freeze-drying improves its handling and storage. The purpose of this project was to determine key parameters which served to guide the development of a mathematical model able to describe the bovine pericardium freeze-drying process and achieve its validation. The study of the freezing step in the bovine pericardium freeze-drying was done by analyzing the time of the process and the residual moisture content of the dried product. Mathematical modeling of the process was shown from the determination of sublimation rates by freeze-drying microscopy under different chamber pressures and heating rates. The freeze-dried products were evaluated for the maintenance of their physical properties. The results revealed that slow freezing with thermal treatment had short process time and low residual moisture of the final product. The mathematical model demonstrated the bovine pericardium freeze-drying and the product indicated no change in their physical properties after the process. Thus, the freeze-drying microscopy analysis was validated in determining the sublimation rate during the bovine pericardium freeze-drying and the process was endorsed through mathematical modeling.
238

Otimização da liofilização do pericárdio bovino com o auxílio de ferramentas matemáticas / Freeze-drying optimization of bovine pericardium by mathematical modeling

Camila Figueiredo Borgognoni 01 October 2009 (has links)
A liofilização é um método de conservação utilizado para a obtenção de produtos desidratados de alta qualidade. É um processo que requer tempo e energia, podendo levar dias para terminar se o ciclo de liofilização não for otimizado. O objetivo da otimização do processo de liofilização é minimizar o consumo de energia e reduzir o tempo de processo, sem que ocorra a perda na qualidade do produto liofilizado. A utilização de modelos matemáticos que predizem o comportamento do produto durante a liofilização pode reduzir drasticamente o número de experimentos, além de determinar variáveis importantes que não podem ser medidas experimentalmente. Tecidos biológicos são produtos sensíveis que se submetidos à altas temperaturas podem sofrer alterações irreversíveis. O estudo da liofilização do pericárdio bovino tem como objetivo sua conservação, facilitando sua manipulação e armazenamento. O objetivo deste projeto foi o uso da teoria fenomenológica que envolve a liofilização, com a utilização de parâmetros essenciais determinados por experimentos de laboratório, para guiar o desenvolvimento de um modelo matemático capaz de descrever a dinâmica do processo de liofilização do pericárdio bovino para, através de seu estudo e da análise das características do produto liofilizado, alcançar a validação do processo. O estudo do congelamento na liofilização do pericárdio bovino foi feito, determinando-se os tempos de processo e o conteúdo de umidade residual do produto seco. A modelagem matemática do processo foi apresentada a partir da determinação de taxas de sublimação por microscopia óptica acoplada à liofilização, sob diferentes pressões de câmara e taxas de aquecimento de placa. Os produtos liofilizados foram avaliados quanto à manutenção de suas propriedades físicas. Os resultados mostraram que o congelamento lento com tratamento térmico apresentou curto tempo de liofilização e baixo valor de umidade residual do produto final. O modelo matemático demonstrou a liofilização do pericárdio bovino e o produto não apresentou alterações em suas propriedades físicas após o processo. Sendo assim, validou-se a técnica de microscopia óptica acoplada à liofilização na determinação da taxa de sublimação durante a liofilização do pericárdio bovino e validou-se o processo através da modelagem matemática. / Freeze-drying is a method of preservation that provides high-quality dehydrated products. It is a process that requires time and energy and it may take days to finish. Freeze-drying optimization is used to minimize the process time keeping the high quality of the product. Mathematical models that predict the behavior of products during freeze-drying can drastically reduce the number of experiments and determine variables in a study that could not be experimentally measured. Biological tissues are sensitive to heat and might be irreversibly modified. The study of bovine pericardium freeze-drying improves its handling and storage. The purpose of this project was to determine key parameters which served to guide the development of a mathematical model able to describe the bovine pericardium freeze-drying process and achieve its validation. The study of the freezing step in the bovine pericardium freeze-drying was done by analyzing the time of the process and the residual moisture content of the dried product. Mathematical modeling of the process was shown from the determination of sublimation rates by freeze-drying microscopy under different chamber pressures and heating rates. The freeze-dried products were evaluated for the maintenance of their physical properties. The results revealed that slow freezing with thermal treatment had short process time and low residual moisture of the final product. The mathematical model demonstrated the bovine pericardium freeze-drying and the product indicated no change in their physical properties after the process. Thus, the freeze-drying microscopy analysis was validated in determining the sublimation rate during the bovine pericardium freeze-drying and the process was endorsed through mathematical modeling.
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DESENVOLVIMENTO, CARACTERIZAÇÃO E LIBERAÇÃO IN VITRO DE COMPLEXOS DE INCLUSÃO NISTATINA:β-CICLODEXTRINA OBTIDOS POR DIFERENTES MÉTODOS / Development, characterization, and in vitro release of nystatin:β- cyclodextrin inclusion complexes obtained using different methods

Urban, Amanda Migliorini 15 February 2016 (has links)
Made available in DSpace on 2017-07-21T14:13:07Z (GMT). No. of bitstreams: 1 AMANDA URBAN.pdf: 2026856 bytes, checksum: 7295984cf8ff79aae13643c336cd3e59 (MD5) Previous issue date: 2016-02-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Purpose: This study prepared inclusion complexes (IC) between nystatin (Nys) and β-cyclodextrin (βCD), for posterior incorporation into a soft liner denture material, aiming to promote controlled release and a prolonged antifungal effect. Material and methods: Suspensions of Nys:βCD in molar ratios of 1:0.125, 1:0.25, 1:0.5, 1:0.625, 1:1, 1:2, and 1:4 were prepared in triplicate in distilled water, stirred for 24 h, and evaluated regarding phase solubility. The 1:1 and 1:2 molar ratios were selected to obtain IC using the following methods: physical mixture (PM), freeze-drying (FD), and spray-drying (SP). PM was homogeneous blended in a mortar for 15 min. The other IC were dissolved in water/ethanol solution (50:50 v/v), stirred for 24 h, and then submitted to one of the drying methods FD or SP. Drug, βCD, and IC were submitted to the following physicochemical characterization: field emission electron gun microscopy (FEG), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetry (TGA), X ray diffraction (DXR), and nuclear magnetic resonance (NMR). For the in vitro dissolution study, 1:1 FD and SP IC were selected. Previously, a calibration curve of Nys in Milli-Q® water was plotted.The dissolution was made in triplicate using paddle device at 37ºC and 75 rpm during 8 h for Nys and 24 h for IC. The results were evaluated in relation to dissolution profile, efficiency (ANOVA-1 way) and kinetics. Results: Nys presented crystalline morphology and βCD presented more amorphous characteristics in comparison to the drug. PM and FD and SP IC presented more amorphous characteristics with small crystals. FT-IR analysis showed several shifts, reduction in intensity, and peak narrowing in the IC in relation to the non-complexed drugs. DSC analysis showed reduction in intensity of the fusion point peak of Nys in the IC, indicating partial complexation. DXR analysis showed peak size reduction and disappearance of spectral lines (“amorphization”), with SP showing more significant changes. It was proved that Nys was partially included into the βCD cavity in 1:1 FD IC, because a great chemical shift was observed for H5’, which is within the toroidal cavity of the oligosaccharide. Despite there was no statistically significant difference (p=0.1931) among the results of dissolution efficiency at 8 h, the 1:1 FD and SP IC showed an immediate release mechanics of the drug, with the 1:1 FD IC presenting the faster dissolution profile. The Nys and 1:1 FD and SP IC revealed the better kinetic adjustment for the biexponential model. Conclusion: Based on the results obtained by the characterization techniques, it was concluded that nystatin better complexed with β-cyclodextrin in 1:1 molar ratio in FD and SP methods. Freeze-drying inclusion complex 1:1 nystatin:β-cyclodextrin presented the better dissolution profile and biexponential kinetics, and this may result in interesting strategy to the development of pharmaceutical compounds that enable a controlled release when they are incorporated to the soft liner denture material. / Objetivo: A proposta deste estudo foi elaborar complexos de inclusão (CI) entre nistatina (Nis) e β-ciclodextrina (βCD), para a posterior inclusão em material macio para reembasamento de prótese removível, visando promover liberação controlada e permitir efeito antifúngico prolongado. Material e métodos: Suspensões de Nis:βCD em proporções molares de 1:0,125, 1:0,25, 1:0,5, 1:0,625, 1:1, 1:2 e 1:4 foram preparadas em triplicata em água destilada, agitadas por 24 h e avaliadas com relação à solubilidade de fases. As proporções 1:1 e 1:2 foram selecionadas para obtenção de CI a partir dos seguintes métodos: mistura física (MF), liofilização (Lio) e spray drying (SP). A MF foi homogeneizada por 15 min com almofariz e pistilo. Os demais CI foram dissolvidos em solução de água/etanol (50:50 v/v), agitados por 24 h e, então, submetidos a um dos processos de secagem Lio ou SP. Fármaco, βCD e CI foram submetidos às seguintes caracterizações físico-químicas: microscopia eletrônica de varredura por emissão de efeito de campo (FEG), espectroscopia infravermelha por transformada de Fourier (FT-IR), análise térmica diferencial (DSC) e termogravimétrica (TGA), difração de raios X (DRX) e ressonância magnética nuclear (RMN). Para o estudo de dissolução in vitro, foram selecionados os CI 1:1 Lio e SP. Previamente, foi construída uma curva de calibração da Nis em água Milli-Q®. A dissolução foi realizada em triplicata utilizando o aparato pá do dissolutor de cubas a 37ºC e 75 rpm durante 8 h para a Nis e 24 h para os CI. Os resultados obtidos foram avaliados com relação ao perfil, eficiência (ANOVA-1 fator) e cinética de dissolução. Resultados: A Nis apresentou morfologia cristalina e a βCD apresentou características mais amorfas em relação ao fármaco. A MF e os CI Lio e SP apresentaram características mais amorfas com pequenos cristais. A análise em FT-IR mostrou vários deslocamentos, reduções de intensidade e estreitamento de picos nos CI em relação aos fármacos não complexados. A análise de DSC mostrou diminuição da intensidade do pico de ponto de fusão da Nis nos CI, indicando complexação parcial. A análise em DRX mostrou que nos CI houve achatamento e desaparecimento de linhas espectrais (“amorfização”), sendo que no SP as alterações foram mais significantes. Foi comprovado que a molécula de Nis foi incluída parcialmente na cavidade da βCD no CI Lio 1:1, uma vez que foi observado grande deslocamento químico no H5’ do interior da cavidade toroidal do oligossacarídeo. Apesar de não ter sido notada diferença estatisticamente significante (p=0,1931) entre os resultados de eficiência de dissolução ao final de 8 h, os CI Lio e SP 1:1 mostraram uma mecânica de liberação imediata do fármaco, sendo que o CI Lio 1:1 apresentou o perfil de liberação mais rápido. Tanto o perfil de liberação da Nis como dos CI Lio e SP 1:1 revelaram melhor ajuste cinético para o modelo biexponencial. Conclusão: A partir dos resultados obtidos pelas técnicas de caracterização, pôde ser concluído que a nistatina apresentou melhor complexação com a β-ciclodextrina na proporção molar 1:1 nos métodos de Lio e SP. O complexo de inclusão nistatina:β-ciclodextrina 1:1 obtido por Lio apresentou melhor perfil de 10 dissolução e cinética biexponencial, o que pode resultar em estratégias interessantes para o desenvolvimento de formas farmacêuticas que possibilitem uma liberação controlada quando incorporadas ao material macio para reembasamento de prótese dentária.
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AVALIAÇÃO DA QUALIDADE DE PRESUNTO COZIDO E INFLUÊNCIA DO EMPREGO DE MATÉRIA-PRIMA CONGELADA

Los, Francine Gomes Basso 26 February 2014 (has links)
Made available in DSpace on 2017-07-21T18:53:23Z (GMT). No. of bitstreams: 1 Francine Gomes Basso Los.pdf: 1771141 bytes, checksum: 61bbe93b19590943c245c54c1d1d8e91 (MD5) Previous issue date: 2014-02-26 / Meat products’ consumption in Brazil is still low considering the favorable condition of largest exporter of meat in the world. With the increase of income of the population that scenario tends to change with additional consumption. Studies on the quality of products sold in the domestic market need to be constantly conducted in order to assist the high quality and safety of products providing and, as well, new technology and concepts need to be studied to increase the demand for products. Despite the consensus that the freezing of meat affects its functional properties, several studies have been conducted to evaluate its use in processed meat products, in order to increase the availability of raw materials and flexibility of industries. In this context, the objectives of this work were study the quality of cooked hams sold in the domestic market and to classify them by means of multivariate analysis, and study the influence of freezing of raw material and the use of exudate released upon thawing, on cooked ham’s production. To study the quality of cooked hams eleven commercial samples were evaluated for microbiological quality, physico-chemical and rheological, and studied by means of Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA). Regarding to legal standards, eight samples were in accordance with all parameters required by the law, two samples were fraud by the addition of starch, and one sample showed sodium content above stated on the label. The samples were classified by HCA in three groups of distinct quality, with a significant difference in moisture content, chromaticity, losses of syneresis, heating and freezing. Analyzing the results of the sensorial analysis applied and instrumental parameters was possible, by applying PCA, demonstrate that samples more accepted by consumers in relation to flavor and overall acceptability were the samples that showed higher levels of moisture, protein, fat and luminosity. To study the influence of freezing of raw material in cooked ham, pork leg was frozen by slow (-18 º C) and fast method (liquid nitrogen) and maintained for 22 weeks in storage at -18 ° C. After this period the meat samples were thawed and the exudate was collected. Cooked hams were produced with the raw material frozen/thawed by both methods, with and without using exudate. A control sample, with fresh raw material was also produced. Samples of hams were analyzed for physico-chemical, structural (rheological and histological), technological and sensory characteristics. The samples showed no significant difference regarding to the physicochemical, color and sensory analyzes. Statistical difference was observed in hardness and chewiness. Histological analysis showed changes in the tissues caused by the freezing and thawing of raw materials. The effect of increasing exudate was significant only for compression force and sodium content, but still, this difference was not perceived by sensory analyzes. This result indicates the possibility of using frozen meat, under the conditions tested, for cooked ham, which may be interesting from an industrial point of view to increase the flexibility of the processing plants due to the great availability of this type of raw material. This study demonstrated that multivariate techniques were effective in assessing the quality of cooked hams and proved the possibility of using raw frozen this type of product, according to the tested conditions, which may be interesting from an industrial point of view to increase the flexibility of processing plants due to the large availability of such raw materials. / O consumo de produtos cárneos no Brasil ainda é baixo considerando a favorável condição de maior exportador de carnes do mundo. Com o aumento de renda da população esse cenário tende a se modificar, com aumento no consumo de itens de alto valor agregado. Estudos sobre a qualidade de produtos comercializados no mercado nacional precisam ser constantemente conduzidos com o intuito de auxiliar no fornecimento de produtos de alta qualidade e segurança para o consumidor, bem como novas tecnologias e conceitos precisam ser estudados para aumentar a demanda de produtos. Apesar do consenso de que o congelamento de carnes afeta suas propriedades funcionais, vários estudos tem sido realizados para avaliar seu uso em produtos cárneos industrializados, com intuito de aumentar a disponibilidade de matéria-prima e flexibilidade das indústrias. Nesse contexto, os objetivos desse trabalho foram: estudar a qualidade de presuntos cozidos comercializados no mercado nacional e classificá-los por meio de análise multivariada; e estudar a influência do congelamento da matéria-prima cárnea e a incorporação do exsudado liberado no descongelamento, na produção de presunto cozido. Para o estudo da qualidade dos presuntos cozidos onze amostras comerciais foram avaliadas quanto à qualidade microbiológica, físico-química e reológica, e estudadas por meio de Análise Hierárquica de Agrupamentos (HCA) e Análise de Componentes Principais (PCA). Em relação ao atendimento dos parâmetros legais, oito amostras apresentaram-se em conformidade com todos os parâmetros exigidos pela legislação, duas foram consideradas fraudadas por adição de amido e uma amostra apresentou teor de sódio acima do declarado no rótulo. As amostras foram classificadas, por HCA, em três grupos de qualidade distinta, com diferença significativa no teor de umidade, cromaticidade, perdas por sinérese, aquecimento e congelamento. Analisando os resultados da análise de aceitabilidade aplicada e os parâmetros instrumentais avaliados foi possível demonstrar, pela aplicação de PCA, que as amostras mais aceitas pelos consumidores em relação à aceitação global e sabor foram aquelas que apresentaram maiores teores de umidade, proteína, gordura e luminosidade. Para estudar a influência do congelamento da matéria-prima em presuntos cozidos, o pernil suíno foi congelado por método lento (-18 ºC) e rápido (nitrogênio líquido) e mantido por 22 semanas em estocagem a -18 ºC. Após esse período as amostras de carne foram descongeladas e o exsudado foi coletado. Foram produzidos presuntos cozidos com a matéria-prima submetida a ambos os métodos de congelamento, com e sem incorporação do exsudado, e uma amostra controle, com matéria-prima resfriada. As amostras de presunto foram analisadas quanto às características físico-químicas, estruturais (reológicas e histológicas), tecnológicas e sensoriais. As amostras não apresentaram diferença significativa em relação às análises físico-químicas, cor e sensorial. Foi observada diferença estatística nos parâmetros dureza e mastigabilidade. A análise histológica mostrou alteração nos tecidos causada pelo congelamento e descongelamento das matérias-primas. O efeito do exsudado foi significativo apenas para os parâmetros força de compressão e teor de sódio, mas ainda assim, essa diferença não foi percebida sensorialmente. Este trabalho demonstrou que técnicas multivariadas foram eficazes na avaliação da qualidade de presuntos cozidos e comprovou a possibilidade de utilização de matéria-prima congelada nesse tipo de produto, nas condições testadas, o que pode ser interessante do ponto de vista industrial por aumentar a flexibilidade das plantas processadoras devido a grande disponibilidade desse tipo de matéria-prima.

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