This thesis describes the convenient routes and the preparation conditions (temperature, oxygen partial presssure) which lead to the formation of single phase materials within the quaternary system Cu-Ni-Fe-O. The investigated compositions are the solid solutions CuxNi1-xFe2O4, the ferrites occurring in the phase triangle Cu0.5Ni0.5Fe2O4 -Cu0.9Fe2.1O4 - Cu0.5Fe2.5O4 and some copper-nickel oxide solid solutions. Three synthesis routes have been used, namely (i) the preparation and the thermal decomposition of freeze-dried carboxylate precursors, (ii) the preparation and the oxidation of intermetallic phases and (iii) the preparation and the heat treatment in air of mixed oxide/metallic powders. The thermal decomposition of freeze-dried Cu-Ni-Fe formate has been found as a suitable method for preparing single spinel phases within the Cu-Ni-Fe-O system. In comparison with the conventional solid state reaction, the required temperature is much lower. Concerning the solid solution CuxNi1-xFe2O4 , a single phase spinel is formed at 1000¢XC for x < 0.7; for CuO is identified as second phase. In this latter range the formation of a pure phase required an increase of the iron content in the mixture. The other single spinel phases in the phase triangle Cu0.5Ni0.5Fe2O4 - Cu0.9Fe2.1O4 - Cu0.5Fe2.5O4 have been synthesized under special synthesis p(O2)/T-conditions. For copper ferrites Cu1-xFe2+xO4 with x ?­ 0.1, 0.2, 0.33, 0.4 and 0.5, the change in the conductivity with the temperature is irreversible. The deviation from the linearity of the conductivity ?ã as a function of the temperature occurs due to the thermal history of these samples. The saturation magnetic moment (nB) at 5K, of some synthesized CuxNi1-xFe2O4 compounds has been determined. It has been found that nB increases with the nickel content in the ferrite sample.

Un polypeptide néosynthétisé est capable de trouver rapidement le chemin vers sa structure tri-dimensionnelle finale, en passant par des intermédiaires partiellement structurés. L'acquisition d'information sur le rôle et l'importance de ces intermédiaires est rendue difficile parce qu'ils se forment très rapidement pendant la réaction de repliement et que cette période de temps n'est pas accessible aux appareils de mélange usuels.<br />L'objet de cette thèse était de caractériser les évènements cinétiques initiaux du repliement des protéines, notamment de l'apomyoglobine (apoMb), en utilisant des appareils de mélange ultra-rapide. Un appareil de type stopped-flow équipé d'une micro-cuve a permis de diminuer le temps mort de ce type de mélangeur. Une réaction bimoléculaire (NATA et NBS), à permis d'évaluer le temps mort à 400±10 µs, dans un mode d'utilisation permettant de suivre simultanément le signal de fluorescence et le signal de dichroïsme circulaire dans l'UV lointain. L'apoMb est une protéine particulièrement intéressante pour l'étude des évènements précoces du repliement des protéines. Le stopped-flow ultra rapide, a permis de suivre des cinétiques (k jusqu'à 1500 s-1) et montré que chaque étape précédemment identifiée, conduisant l'apoMb de sa forme dépliée à sa forme native (soit les réactions UIa, IaIb, et IbN), présente les caractéristiques typiques d'une réaction à deux états, hautement coopérative.<br />Nous avons étudié l'effet d'osmolytes sur les cinétiques et sur la stabilité à l'équilibre des formes U, I et N de l'apoMb. Des études cinétiques en présence de sucrose ont permis d'observer le comportement de la réactions UIa. Ces résultats indiquent que le sucrose déstabilise de manière relative la forme U et l'état de transition de la réaction UIa, par rapport à la forme Ia. L'étape limitante ne correspondrait donc pas à une compaction de la chaîne peptidique. Dans les mêmes conditions, l'étude de la transition IbN permet d'observer que l'état de transition présente des caractéristiques proches de Ib. Ces résultats, décrivant l'effet osmophobique sur l'intermédiaire I, ainsi que des résultats préliminaires de l'effet d'encombrement moléculaire sur le repliement du cytochrome C, sont discutés dans ce mémoire.

207Pb*/206Pb* chronometry was used to obtain the ages of Ca,Al-rich inclusions (CAIs) and chondrules found in ancient meteorites. Assuming a 238U/235U=137.88, Pb/Pb ages of chondrules in NWA801 (a CR2 meteorite) are 4564.6±1.0 Ma, chondrules in Mokoia (a CV3 chondrite) are 4564.2±1.1Ma, and CAIs in Mokoia are 4567.9±5.4 Ma. The Pb/Pb age of NWA801 chondrules is concordant with 26Al/26Mg ages of CR chondrules. However if a 238U/235U < 137.88 is used, the age for NWA801 chondrules becomes younger by ~1Ma and discordant with 26Al/26Mg ages of CR chondrules. This suggests either a discrepancy with the U compositions or the initial Mg isotopic compositions of NWA801 chondrules. The shapes of NWA801 chondrules, and blebs of FeNi metal in the meteorite matrix, were further studied by 3D X-ray micro-computed tomography (CT). Most chondrules (92%) were ‘armoured’ with one discontinuous layer of FeNi metal. Two layers of FeNi metal (one on the exterior and one concentric through the interior separated by silicate) were rare <8%. Chondrules and matrix blebs occur as oblates, prolate, spheres and triaxial spheroids. It is proposed that the shapes were made free-floating in the nebula likely by flash-melting precursors into molten droplets that were vibrating as harmonic oscillators that ‘froze-in’ their shapes during cooling. Parent-body metamorphism and shock are not likely processes affecting the matrix-bleb and chondrule shapes. Chondrules with ≥2 FeNi metal layers were likely formed by mergers and not by successive deposition and annealing of metal in multiple flash-melting events. Attempts to obtain 207Pb*/206Pb* ages from chondrules and CAIs by thermal extraction (TE)- TIMS were unsuccessful. However LA-ICP-MS was shown to be useful for rapidly determining Pb isotopic trends in meteorites and unknown objects. In particular, it was shown that 137La (T1/2=60ky) should be detectable in recently fallen meteorites using LaF−4 to suppress the 137Ba isobar during tandem accelerator mass spectrometry combined with a novel instrumental technique for isobar separation.

207Pb*/206Pb* chronometry was used to obtain the ages of Ca,Al-rich inclusions (CAIs) and chondrules found in ancient meteorites. Assuming a 238U/235U=137.88, Pb/Pb ages of chondrules in NWA801 (a CR2 meteorite) are 4564.6±1.0 Ma, chondrules in Mokoia (a CV3 chondrite) are 4564.2±1.1Ma, and CAIs in Mokoia are 4567.9±5.4 Ma. The Pb/Pb age of NWA801 chondrules is concordant with 26Al/26Mg ages of CR chondrules. However if a 238U/235U < 137.88 is used, the age for NWA801 chondrules becomes younger by ~1Ma and discordant with 26Al/26Mg ages of CR chondrules. This suggests either a discrepancy with the U compositions or the initial Mg isotopic compositions of NWA801 chondrules. The shapes of NWA801 chondrules, and blebs of FeNi metal in the meteorite matrix, were further studied by 3D X-ray micro-computed tomography (CT). Most chondrules (92%) were ‘armoured’ with one discontinuous layer of FeNi metal. Two layers of FeNi metal (one on the exterior and one concentric through the interior separated by silicate) were rare <8%. Chondrules and matrix blebs occur as oblates, prolate, spheres and triaxial spheroids. It is proposed that the shapes were made free-floating in the nebula likely by flash-melting precursors into molten droplets that were vibrating as harmonic oscillators that ‘froze-in’ their shapes during cooling. Parent-body metamorphism and shock are not likely processes affecting the matrix-bleb and chondrule shapes. Chondrules with ≥2 FeNi metal layers were likely formed by mergers and not by successive deposition and annealing of metal in multiple flash-melting events. Attempts to obtain 207Pb*/206Pb* ages from chondrules and CAIs by thermal extraction (TE)- TIMS were unsuccessful. However LA-ICP-MS was shown to be useful for rapidly determining Pb isotopic trends in meteorites and unknown objects. In particular, it was shown that 137La (T1/2=60ky) should be detectable in recently fallen meteorites using LaF−4 to suppress the 137Ba isobar during tandem accelerator mass spectrometry combined with a novel instrumental technique for isobar separation.

This project concerns the effect of freeze-thaw cycles on the pore-scale structure of nonaqueous phase liquid (NAPL) contaminants in water-saturated porous media. This problem is of critical importance to the entrapment of such contaminants in cold temperate, polar and high altitude regions, and has not been examined in the literature to date. This research work is conducted in three stages: (i) two-dimensional nondestructive visualisation of residual light non-aqueous phase liquid (LNAPL), and dense non-aqueous phase liquid (DNAPL), in porous media subject to successive freeze-thaw cycles; (ii) three-dimensional experiments on LNAPL in porous media subject to freeze-thaw, with quantification of phase volumes by X-ray micro-computed tomography (micro-CT); and (iii) the explanation of results by several pore scale mathematical and conceptual models. The two-dimensional cell experiments (using a monolayer of 0.5 mm diameter glass beads held between two glass sheets), and three-dimensional X-ray micro-CT experiments reveal a substantial mobilisation and rupture of ganglia during successive freeze-thaw cycles; this includes the detachment of smaller ganglia from larger ganglia and the mobilisation of NAPL in the direction of freezing front. The experiments also reveal significant shedding of numerous single/sub-singlet ganglia along narrow pore corridors, their entrapment in growing polycrystalline ice, and the coalescence of such small ganglia during thawing to form larger singlets. These changes were more predominant where the freezing commenced. The results of the experimental studies were interpreted by developing several mathematical and conceptual models, including freezing-induced pressure model, Darcy's law model, multipore ganglia model (rupture coefficient) and ice-snap off model.

Diss. Linköping : Univ., 2003.

La présente étude concerne l’évaluation de l’impact du séchage par air chaud (HAD), lyophilisation (FD) et « swell drying » (SD), procédé couplant le séchage par air chaud avec le procédé de Détente Instantanée Contrôlée (DIC), sur les fraises (Fragaria var. Camarosa). Il s’agit de comparer et de contraster les performances des procédés et la qualité du produit fini séché en termes des cinétiques de séchage et de réhydratation, de contenus en molécules bioactives et activité antioxydante, et des paramètres caractéristiques de texture comme croquant et croustillant. Les résultats obtenus ont montré que le procédé de SD comparé aux procédés classiques de séchage et de lyophilisation, réduit d’une façon importante le temps de séchage ainsi que les coûts d’opération. D’autre part, SD conserve la qualité nutritionnelle des fraises en gardant leur contenu en composants bioactifs et en augmentant leur disponibilité. De plus, une corrélation importante entre la capacité antioxydante et le contenu total d’anthocyanes a été établie. D’autre part, les fraises séchées par SD ont montré une très intéressante macro et micro-structure. Les produits ont présenté une haute expansion et une croustillance significative due au phénomène de micro-alvéolation par décompression instantanée par DIC. D’ailleurs, il a été possible de mesurer les caractéristiques instrumentales de croustillance/croquance des échantillons finaux séchés. Grâce à la possibilité de modifier, contrôler et optimiser les paramètres opératoires du procédé DIC, il a été possible d’obtenir un produit du type « snack » croustillant avec une très haute valeur nutritionnelle. / The aim of this study was to evaluate the effect of hot air drying (HAD), freeze-drying (FD) and swell drying (SD), which is a coupling of hot air drying to instant controlled pressure drop, (DIC) on the strawberry (Fragaria var. Camarosa) to compare and to contrast its quality in terms of drying and rehydration kinetics, bioactive compounds and its antioxidant activity, and texture parameters as crunchy and crispy features. The obtained results shown that SD method helped to reduce the drying time leading to a low-cost processing compared with classical hot air drying and freezedrying. SD globally preserved the strawberry’s nutritional value and bioactive compounds, increasing their availability. Moreover, a strong correlation between antioxidant activity and total anthocyanin content was established in SD strawberries. On the other hand, the swell-dried strawberries showed an interesting macro and micro-structure. They presented a high expansion ratios and significant crispness provoked by the micro-alveolation phenomenon induced as consequence of the instant decompression process in the DIC treatment. Moreover, it was possible to instrumentaly measure the crispy/crunchy features of the final dried samples. By assessing such crispy and healthy contents of fruit “snacking”, it was possible to modify, control, and optimize DIC operating parameters. And, it can be designed according to the industrial or consumer needs.

OLIVEIRA, Gleison Silva. Aplicação do processo de liofilização na obtenção de cajá em pó: avaliação das características físicas, físico-químicas e higroscópicas. 2012. 83 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Tecnologia de Alimentos, Fortaleza-CE, 2012 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-09T12:17:09Z No. of bitstreams: 1 2012_dis_gsoliveira.pdf: 1196468 bytes, checksum: a8572b9d75384ed2a57b461af4d5a3bf (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-09T12:17:20Z (GMT) No. of bitstreams: 1 2012_dis_gsoliveira.pdf: 1196468 bytes, checksum: a8572b9d75384ed2a57b461af4d5a3bf (MD5) / Made available in DSpace on 2016-06-09T12:17:20Z (GMT). No. of bitstreams: 1 2012_dis_gsoliveira.pdf: 1196468 bytes, checksum: a8572b9d75384ed2a57b461af4d5a3bf (MD5) Previous issue date: 2012 / The yellow mombin due to its distinctive flavor and pleasant, is a fruit highly appreciated and consumed in various regions of the country. But by presenting a high perishability, it becomes necessary to use processing techniques to extend its availability for consumption throughout the year. Dehydration by freeze-drying has the advantage of an excellent retention of nutritional and sensory characteristics of fresh fruit. To increase retention and to prevent agglomeration of the powder, for example, can be made the use of adjuvants drying such as maltodextrin. In this context, the work aimed at the implementation of the lyophilization process to obtain the pulp of yellow mombin powder, physical characterization and physicochemical pulp and powder yellow mombin, tracking stability during storage and hygroscopic behavior of the tests. With the tests of the experimental design was chosen to test lower humidity, with 17% maltodextrin and 24 hours of freeze drying. The pulp presented characteristics similar to reported by literature, and a concentration of constituents occurred with the pulp dehydration. As for storage, the test control (dried whole) had a useful life of 60 days, unlike the test containing maltodextrin that showed good characteristics throughout the period analyzed. In addition, maltodextrin exerted protective function, preventing further loss of chemical constituents and physical reactions to the product, such as lower rate of increase of hygroscopicity, moisture and water activity. The adsorption isotherms were the characteristics of type III. The mathematical models of BET, GAB and Oswin were the best fit to experimental data of moisture sorption for the full hog plum powder, and powder of hog plum pulp with maltodextrin, the Henderson model was the best fit to experimental points of work. / O cajá, devido ao seu sabor diferenciado e agradável, é um fruto bastante apreciado e consumido em diversas regiões do país. Mas por apresentar uma elevada perecibilidade, torna-se necessário o uso de técnicas de processamento para estender sua disponibilidade para o consumo durante todo o ano. A desidratação por liofilização apresenta como vantagem uma excelente retenção das características nutricionais e sensoriais do fruto “in natura”. Para um aumento desta retenção e evitar aglomerações no pó, por exemplo, pode ser feita a utilização de adjuvantes de secagem como a maltodextrina. Neste contexto, o trabalho teve como objetivo a aplicação do processo de liofilização para obtenção da polpa de cajá em pó, caracterização física e físico-química da polpa e do pó de cajá, acompanhamento da estabilidade durante o armazenamento e comportamento higroscópico dos ensaios. Com a realização dos ensaios do planejamento experimental, foi escolhido o ensaio de menor umidade, com 17% de maltodextrina e 24 horas de liofilização. A polpa apresentou características semelhantes às reportadas pela literatura, e uma concentração dos constituintes ocorreu com a desidratação da polpa. Quanto ao armazenamento, o ensaio controle (pó integral) teve uma vida útil de 60 dias, diferentemente do ensaio contendo maltodextrina que apresentou boas características durante todo período analisado. Além disso, a maltodextrina exerceu função protetora, evitando maiores perdas de constituintes químicos e reações físicas no produto, como menor taxa de aumento de higroscopicidade, umidade e atividade de água. As isotermas de adsorção foram características às do tipo III. Os modelos matemáticos de BET, GAB e Oswin foram os que melhor se ajustaram aos dados experimentais de sorção de umidade para o pó de cajá integral, e no pó da polpa de cajá com maltodextrina, o modelo de Henderson foi o que melhor se ajustou aos pontos experimentais do trabalho.

Magister Pharmaceuticae - Mpharm / The aim of this study was to determine quality control specifications needed for a dossier and an investigator's brochure of A. afra capsules, which can be used to motivate the registration and clinical testing of A. afra capsules in chronic asthma. The specific objectives were: (1) to establish the minimum product quality requirements for registration of A. afra capsules, (2) to prepare and pharmaceutically characterize a capsule product of A. afra freeze dried aqueous extract (FDAE) suitable for registration, and (3) to identify pharmaceutical product quality aspects of an investigator's brochure (IB) that would be appropriate for use in motivating a clinical trial of A. afra capsules in chronic asthma.

Made available in DSpace on 2016-06-02T19:56:39Z (GMT). No. of bitstreams: 1 3124.pdf: 1709285 bytes, checksum: 01aa5e6d0190ca5658a75e9fefae9b2b (MD5) Previous issue date: 2010-05-28 / Financiadora de Estudos e Projetos / The cultivation of pepper is widespread in Brazil since its colonization. This plant, besides being much appreciated in the cuisine has proven pharmacological effects such as lowering cholesterol, inhibiting appetite and the presence of antioxidants such as ascorbic acid and beta-carotene. It is a product whose demand increases every year, but generally still produced handmade diminish the ability of producers to meet the needs of commerce. To contribute to improving the production of pepper dedo-de-moça, it was the behavior of this plant in analyzing the influence of drying process on the nutritional composition and physical qualities of the dried product. For this, drying kinetics were obtained and certain structural properties (apparent density, real density and porosity) as a function of moisture content during drying. Assessing the quality of the final product was performed by quantification of ascorbic acid and study of rehydration. The convective drying and freeze-drying was compared with respect to product quality parameters such as shrinkage, structural properties, vitamin C retention and rehydration characteristics. To describe the kinetics of drying and rehydration were used empirical and semiempirical equations. The characterization of the rehydration process was carried out from the indices that take account of the capacity of water absorption and loss of solutes. The use of seed from the drying of peppers to obtain seedlings was studied by checking the germination through standardized tests. The samples of convective drying at 60 ºC had the best results in terms of nutritional quality, rehydration characteristics and structural properties, comparing with those obtained from freezedrying. In assessing the use of seeds of peppers after processing to obtain new seedlings, the most suitable temperature was 40 oC to cause less damage to germination. / A cultura da pimenta está bem difundida no Brasil desde a sua colonização. Esse vegetal, além de ser muito apreciado na culinária possui efeitos farmacológicos comprovados como o de redutor do colesterol, inibidor do apetite e a presença de substâncias antioxidantes como o ácido ascórbico e o beta-caroteno. É um produto cuja demanda aumenta a cada ano, mas que a forma como é produzido continua, em sua maioria, artesanal diminuindo a capacidade dos produtores de atender às necessidades do comércio. Visando contribuir para o melhoramento da produção da pimenta dedo-de-moça, verificou-se o comportamento desse vegetal na secagem analisando a influência do processo na composição nutricional e qualidades físicas no produto seco. Para isso, foram obtidas as cinéticas de secagem e a determinação das propriedades estruturais (densidade aparente, densidade real e porosidade) em função do teor de umidade durante a secagem. A avaliação da qualidade do produto final foi realizada pela quantificação de ácido ascórbico e estudo da reidratação. A secagem convectiva foi comparada com a secagem em liofilizador com relação a parâmetros de qualidade do produto como encolhimento, propriedades estruturais, retenção de vitamina C e características de reidratação. Para descrever a cinética de secagem e de reidratação foram utilizados modelos empíricos e semi-empíricos. A caracterização do processo de reidratação foi realizada a partir dos índices que levam em conta a capacidade de absorção de água e a perda de solutos. Avaliou-se também o aproveitamento das sementes resultantes do processamento para obtenção de novas mudas através da verificação da capacidade germinativa por meio de testes padronizados. As amostras obtidas da secagem por convecção a 60oC tiveram os melhores resultados em termos de qualidade nutricional, características de reidratação e propriedades estruturais, comparando-se com aquelas obtidas da liofilização. Na avaliação do uso das sementes após o processamento das pimentas para obtenção de novas mudas, a temperatura mais adequada foi de 40oC por causar menos prejuízo a capacidade germinativa.