O objetivo desta pesquisa é identificar e compreender a contradição estabelecida entre o processo de degradação das Vilas Preservadas na Baixada do Glicério, localizada na região central da cidade de São Paulo, e a proposta de renovação urbana do mesmo centro por meio da Lei da Operação Urbana Centro (OUC), a qual se utiliza de instrumentos de preservação do patrimônio com a finalidade de possibilitar novas frentes de valorização do capital. O método de investigação, realizado a partir da análise do discurso e das proposições das políticas públicas, possibilitou constatar as diversas formas de operar com a idéia da degradação, diretamente relacionada ao contexto de desinvestimento. Neste contexto, além da política de renovação urbana dirigida ao centro da cidade de São Paulo e consolidada pela lei da Operação Urbana Centro, as noções de degradação e de congelamento também foram consideradas centrais no desenvolvimento desta pesquisa. Assim, como verificado com a análise das determinações da OUC no Glicério, pudemos entender que a degradação, ou ainda, o congelamento de determinadas áreas são produzidos historicamente pelas relações contraditórias contidas no processo de urbanização. São mantidas como frentes de valorização, a serem inseridas no processo de reprodução do espaço, no contexto da renovação urbana. É neste contexto que se caracteriza a preservação contraditória das vilas da Baixada do Glicério analisadas neste estudo, cujo instrumento de proteção acabou por intensificar seu processo de degradação, permanecendo sob o denominado estado de congelamento. / The purpose of this research is to identify and understand the contradictions between the established process of deterioration in the Baixada do Glicério, located in the region of central city of São Paulo, and the proposal for urban renewal of the same Centre by means of the Operação Urbana Centro (OUC), which is a Law that used instruments of preservation with the aim of enabling new fronts of capital valorization. The method of research, carried out from the analysis of speech and the headings of public policy, has enabled note the various forms of operating with the meanings of degradation, directly related to the context of disinvestment. In this context, in addition to the policy of urban renewal to the centre of the city of São Paulo and consolidated by the OUC, the concepts of degradation and freezing also were considered central to the development of this research. Thus, as occurred with the analysis of determinations by the OUC in Baixada do Glicério, we believe that the degradation, or even, the freezing of certain areas are produced by relations historically contradictory contained in the process of urbanization. Are maintained as fronts for valorization, to be included in the process of space reproduction, in the context of urban renewal. In this context, it is the hallmark of the contradictory preservation in Baixada do Glicério examined in this study, whose instrument of protection has intensified its process of deterioration, remaining under the state of freezing.

Com o objetivo de analisar a influência do fenômeno de congelamento e o tempo de criopreservação sobre as propriedades biomecânicas de tendões, os autores estudaram 40 tendões de Aquiles obtidos de 20 cadáveres humanos. De cada cadáver foram retirados dois tendões, sendo que um foi testado a fresco e o contralateral congelado a - 85o C, durante um período de seis ou 12 semanas. Os corpos de prova foram submetidos a ensaios de tração, com análise de suas propriedades biomecânicas. Os resultados foram comparados estatisticamente pelo método de "t-student", com índice de significância de 0,05, não havendo diferença significativa entre os grupos "congelado" e "a fresco" / For the purpose of analyzing the influence of the freezing phenomenon and cryopreservation time over the biomechanical properties of tendons, the authors studied 40 Achilles tendons from 20 human cadavers. Each cadaver had two tendons removed, one of which was tested whilst fresh and its contralateral whilst frozen at - 85o C, for a period of six or 12 weeks. The trial items were submitted to tensile testing in order to analyze their biomechanical properties. The results were compared statistically using the T-Student method, with a significance ratio of 0.05, there being no significant difference between the 'frozen' group and the 'fresh' group

As técnicas de cultivo de folículos e oócitos in vitro, com o objetivo de se obter oócitos maduros para procedimentos de Reprodução Assistida (RA), têm sido aplicadas em diferentes contextos. O sucesso destes procedimentos está diretamente relacionado ao sistema de cultivo utilizado. A utilização de células da granulosa (CG) humanas cultivadas in vitro como um suporte para o co-cultivo destes oócitos imaturos e folículos tem sido descrita por alguns autores. A criopreservação destas células, considerando-se o contexto de sua obtenção em procedimentos de RA, permitiria a viabilização da aplicação destas células na prática clínica diária. Sendo assim, o objetivo deste estudo foi padronizar o congelamento de células da granulosa (CG) humanas para aplicação em sistemas de co-cultivos de folículos e oócitos imaturos. Foram obtidas CG de 20 voluntárias em tratamento de reprodução assistida, células de 10 voluntárias foram cultivadas em meio ?-MEM suplementado para interrupção da luteinização e congeladas após 48 horas em container \"Cryostep\" (grupo 2C- 2 cultivos) (etapa 2) e células de 10 voluntárias foram congeladas em container \"Cryostep\" sem cultivo prévio (grupo CD- congelamento direto) (etapa 3). Após o descongelamento estas células foram (re)cultivadas por 144 horas, com troca de meio em 48, 96 e 144 horas para avaliações da produção de estradiol (E2) e progesterona (P4) (ng/mL). Verificamos redução na contagem celular e na viabilidade celular tanto no método de congelamento direto (CD) quanto no método com dois cultivos (2C) após o descongelamento (p<0,05), e isso se refletiu na produção de estradiol e progesterona que foi maior nas culturas de células frescas em relação às células criopreservadas (p<0,05). Porém, a relação de E2/célula foi mantida após o descongelamento, sugerindo que esta redução na produção se deve à redução no número de células, as que sobrevivem se mantém normofuncionantes (p=0,23).O CD foi mais eficiente pois permitiu uma maior recuperação celular e uma melhor viabilidade quando comparado ao grupo 2C. A relação estradiol/progesterona foi mantida em todos os tempos de cultivo, fresco, CD e 2C (p>0,05), indicando que a característica funcional destas células foi preservada após o descongelamento. Concluímos que a criopreservação de CG humanas obtidas durante a captação de oócitos compromete a contagem celular e a viabilidade geral da cultura, entretanto, a capacidade funcional e a característica destas células se mantêm preservadas (manutenção das relações E2/célula e E2/P4) / Follicle and oocyte in vitro culture techniques, aiming to obtain mature oocytes for Assisted Reproductive Treatments (ART), have been applied to different contexts. The success of these procedures depends on the culture system used. The use of human granulosa cells (GC) in co-culture systems for follicle and oocyte maturation have been described by some authors. The cryopreservation of these cells, considering the context in which they are obtained during ART, would enable the usage of these cells in such procedures in daily clinical practice. Thus, the objective of this study was to standardize the freezing protocol for human granulosa cells (GC) for future applications in co-culture systems for follicle and oocyte maturation. Twenty volunteers submitted to ART donated their granulosa cells after oocyte retrieval, 10 were cultivated previously in order to interrupt the luteinization process and then frozen \"Cryostep\" container (group 2C- two cultures) (step 2) and 10 were directly frozen with no previous culture in the \"Cryostep\" container (group DF- direct freeze) (step 3). After thawing these cells were (re)cultured for 144 hours, with medium exchange at 48, 96 and 144 hours to evaluate the estradiol (E2) and progesterone (P4) production (ng/mL). After thawing, there was a reduction in the cell number (p<0,05) and cell viability in both methods, the direct freezing (DF) and the two cultures (2C) (p<0,05); this had an impact in the production of estradiol and progesterone, which were higher in fresh cultures than in the frozen ones (p<0,05). However, the E2/cell ratio was maintained after thawing (p=0.23), suggesting that this impairment in steroid production was probably due to the reduction in the cell count. The cells that survive remain functionally normal. The DF was more efficient since it allowed greater cell recovery and better viability when compared to 2C. The estradiol/progesterone ratio was maintained in all culture times, in the fresh, DF or 2C groups (p>0.05), indicating that the functional characteristic of these cells was preserved post-thawing. We conclude that cryopreservation of human GC obtained during oocyte retrieval compromises the cell count and the overall viability of the culture; however, the functional capacity and the characteristic of these cells are preserved (maintenance of E2/cell and E2/P4 relations)

Orientador: Elenice Aparecida de Moraes Ferrari / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-23T06:24:39Z (GMT). No. of bitstreams: 1 Faria_LarissaOliveiraMellonide_M.pdf: 1121073 bytes, checksum: 5a3108ca0447b5fae98988b4611d7616 (MD5) Previous issue date: 2013 / Resumo: O óxido nítrico (NO) é um neurotransmissor não convencional o qual tem papel importante em processos neurobiológicos de comportamento e de memória. Sua síntese é mediada por três isoformas de sintase do óxido nítrico (NOS): a neuronal (nNOS), a endotelial (eNOS) e a induzível (iNOS). Este trabalho investigou os efeitos da administração do 7- nitroindazol (7-NI), inibidor preferencial da nNOS, na consolidação e reconsolidação da memória do condicionamento clássico aversivo. Pombos adultos foram atribuídos a 5 grupos: Foram usados 5 grupos: grupo 7-nitroindazole (7-NI) (100nmol/0.5?/l; DMSO (20%), NaOH (50mM) e Tween-80 (16%) diluído em PBS; i.c.v.), grupo veículo (VEIC) (0,5?/l; DMSO (20%), NaOH (50mM) e Tween-80 (16%) diluído em PBS, i.c.v.), grupo condicionado/não tratado (COND), grupo contexto/não-tratado (CONT) e grupo não tratado/não condicionado (NÄIVE). Sete dias após implante de microcânula intracerebroventricular (i.c.v.), ocorreu o condicionamento com três associações contextochoque numa sessão de 20 min. O teste e o re-teste consistiram na re-exposição ao contexto do condicionamento por 5 min. O intervalo entre sessões foi de 24h. A administração de 7-NI ou do veículo ocorreu imediatamente após o treino (Experimento 1) ou após o re-teste (Experimento 2). A atividade enzimática da NOS dependente e independente de Ca2+ e da expressão protéica da nNOS foram realizadas no tecido hipocampal. No Experimento 1, a ocorrência de congelamento no teste do 7-NI foi menor do que no treino (p<0.01) e no teste do COND e VEIC (p < 0.001). A atividade da NOS dependente de Ca++ no 7-NI foi menor do que no COND e VEIC (p<0,01), mas não diferiu do CONT e do NÄIVE. A expressão protéica de nNOS não diferiu entre os grupos (p<0,05). No Experimento 2, houve diminuição dos comportamentos defensivos, incluindo o congelamento, no re-teste do 7-NI comparado com VEIC e COND (p<0.05), mas os grupos não diferiram quanto à atividade de NOS dependente de Ca2+ ou à expressão protéica da nNOS. Conclui-se que o 7-NI interferiu na consolidação e a reconsolidação da memória, indicando a ativação da via de sinalização do óxido nítrico no hipocampo em processos da memória de medo condicionado ao contexto em pombos / Abstract: Nitric oxide (NO) is an unconventional neurotransmitter which plays an important role in neurobiological processes of behavior and memory. Its synthesis is mediated by three isoforms of nitric oxide synthase (NOS): the neuronal (nNOS), the endothelial (eNOS) and the inducible (iNOS). This study investigated the effects of the administration of 7- nitroindazole (7-NI), a preferential nNOS inhibitor, in the consolidation and reconsolidation of aversive classical conditioning memory. Adult male pigeons were assigned to 5 groups: 7-nitroindazole, 7-NI (100nmol/0.5?/l; DMSO (20%), NaOH (50 mM) and Tween-80 (16%) diluted in PBS; i.c.v.) Vehicle group; VEH (0.5 ? / L; DMSO (20%), NaOH (50 mM) and Tween-80 (16%) diluted in PBS; i.c.v.), conditioning/non-treated group (COND), context/non-treated group (CONT) and non-conditioning/non-treated group (NÄIVE). Seven days after implantation of intracerebral ventricular (i.c.v.) microcannula the conditioning occurred with three context-shock associations in a session of 20 min. During the testing and retesting sessions pigeons were reexposed to the conditioning context for 5 min. The between sessions interval was 24h. Administration of 7-NI or vehicle occurred immediately after training (Experiment 1) or after testing (Experiment 2). The enzymatic activity of Ca2+ dependent and independent NOS and protein expression of nNOS in the hippocampus tissue were carried out following the behavioral test or retest. In Experiment 1, the occurrence of freezing in the testing session of 7-NI group was lower than in the training (p <0.01) and the testing sessions of COND and VEH groups (p <0.001). The activity of Ca2+ dependent NOS in the 7-NI group was lower than in COND and VEH groups (p <0.01) but did not differ from CONT and NÄIVE groups. The nNOS protein expression in the hippocampus did not differ among the different groups (p<0.05). In Experiment 2, there was a decrease of defensive behaviors, which include freezing, in the retest of the 7-NI compared with VEH and COND groups (p <0.05), but the groups did not differ in the activity of Ca2+ dependent NOS or the protein expression of nNOS. We conclude that 7-NI interfered on the consolidation and reconsolidation of memory, indicating activation of the nitric oxide signaling pathway in the hippocampus and in memory processes of conditioned fear context in pigeons / Mestrado / Fisiologia / Mestra em Biologia Funcional e Molecular

Made available in DSpace on 2014-08-20T13:32:49Z (GMT). No. of bitstreams: 1 dissertacao_kaue_rodriguez_martins.pdf: 452926 bytes, checksum: ae46017afbe7b23ca7e1d34a015987fa (MD5) Previous issue date: 2014-03-19 / There is a growing interest in using artificial insemination (AI) in sheep due to the potential for genetic improvement. However, cryopreservation damages spermatozoa, decreasing their fertilizing potential when frozen semen is deposited in the cervix. Sperm damages attributed to cryopreservation may be minimized by the addition of seminal plasma (SP), which contains several factors produced by the testis, epididhymis and accessory glands with potential to prevent premature capacitation. Supplementation of SP prior to freezing would be beneficial for various processes of periods of the selection and freezing process, reported before freezing would be beneficial for the processes of selection and freezing. The supplementation of extenders with SP from ram and boars is associated with increased sperm motility after incubation in vitro, as well as when used for cooling, freezing and thawing. The objectives of this study were to test the addition of 20% boar SP to the extender to freeze ram sperm and to evaluate parameters of sperm quality after thawing. Ejaculates from four rams and three boars were collected to form pooled SP samples. A fraction of each pooled sample was used for protein quantification. Six samples from four rams were collected and diluted in Tris-egg yolk - glycerol for freezing, forming three treatments: control (no SP); inclusion of 20% ram SP; and inclusion of 20% boar SP. After thawing, the samples were subjected to a thermal stress test for five hours. Sperm quality was assessed every two hours. Analyses by flow cytometry were done to evaluate the integrity of acrosome and membrane integrity. For the control, ram SP and boar SP treatments, the evaluated parameters of sperm quality were: motility (30.4 ± 2.0, 24.6 ± 2.0 and 30.0 ± 2.0, respectively); membrane integrity (37.5 ± 2.6; 40.9 ± 2.6 and 31.4 ± 2.6 respectively); mitochondrial functionality (70.0 ± 1.7; 61.8 ± 1.7 and 63.6 ± 1.7); and DNA integrity (91.2 ± 3.1; 96 5 ± 3.1 and 93.6 ± 3.1 respectively). For those parameters, no significant differences were observed across treataments (P > 0.05). However, addition of boar SP to the extenders was related to greater acrosome integrity (59, 3 ± 3.5) than that of the control (46.7 ± 3.5) (P < 0.05), although both means were similar (P > 0.05) to that observed for the treatment with ram SP (56.7 ± 3.5). Despite of the benefit on acrosome integrity related to addition of boar SP, no other positive effects were observed for post-thawing ram sperm viability. / O interesse pelo uso da inseminação artificial (IA) em ovinos vem crescendo, em função do avanço no melhoramento genético. Entretanto, a criopreservação causa danos aos espermatozóides, diminuindo seu potencial fertilizante, quando a IA é feita com sêmen congelado, pela via cervical. Uma alternativa para proteger ou recuperar a célula dos danos da criopreservação é a adição de plasma seminal (PS), que contém vários fatores produzidos pelos testículos, epidídimos e glândulas acessórias do macho, com potencial de prevenir a capacitação prematura e danos gerados pelo congelamento. A adição de PS antes do congelamento seria benéfica para os processos de seleção e congelamento. A suplementação do diluente com PS ovino e suíno foi associada com aumento na motilidade espermática, após a segunda hora de incubação sob condições in vitro, assim como quando usado na refrigeração, congelamento e descongelamento. Este estudo teve como objetivo testar a adição de PS suíno (20%) ao diluente para congelamento do sêmen ovino e avaliar os parâmetros seminais in vitro pós-descongelamento. Ejaculados de quatro machos ovinos e três machos suínos foram coletados para formação de amostras combinando PS de vários machos (pools). Uma fração das amostras de PS foi destinada a quantificação de proteínas. Seis coletas dos quatro machos ovinos foram colhidas e diluídas em Tris-gema de ovo-glicerol, para congelamento, compondo três tratamentos: controle (sem PS); inclusão de 20% de PS ovino; e inclusão de 20% PS suíno. Após o descongelamento, as amostras foram submetidas a um teste de termo resistência durante cinco horas. Avaliações de qualidade espermática foram realizadas a cada duas horas. Também foram realizadas análises por citometria de fluxo para as avaliações de integridade de acrossoma e integridade de membrana. Para os tratamentos controle, PS ovino e PS suíno, não foram observadas diferenças (P > 0.05) quanto a motilidade (30,0 ± 2,0; 30,4 ± 2,0 e 24,6 ± 2,0 respectivamente), integridade de membrana (37,5 ± 2,6; 40,9 ± 2,6 e 31,4 ± 2,6, respectivamente), função mitocondrial (70,0 ± 1,7; 61,8 ± 1,7 e 63,6 ± 1,7, respectivamente) e integridade de DNA (91,2 ± 3,1; 96,5 ± 3,1 e 93,6 ± 3,1, respectivamente). A integridade do acrossoma foi maior (P < 0.05) com inclusão de PS suíno (59,3 ± 3,5) em comparação com o controle (46,7 ± 3,5), mas ambas as médias foram similares (P > 0.05) à observada para o PS ovino (56,7 ± 3,5). Conclui-se que apesar do beneficio do PS suíno a 20% para a integridade de acrossoma, não se obteve resultados positivos nas demais avaliações de qualidade seminal.

La thèse s’intéresse à la problématique de la répétition dans le discours. Le langage de la répétition relève de la doxa, mot que nous avons utilisé dans la thèse comme le terme générique qui englobe cette réalité complexe que Nathalie Sarraute dénonce dans son œuvre en s’attaquant au réalisme discursif. Il s’agit d’étudier dans un corpus littéraire le langage figé qui exprime des réalités figées. C’est un langage qui s’appuie sur un système de référence prototypique. Le référent est soit un objet, soit une propriété ou un processus isolable dont les réalistes considèrent qu’il existe en dehors de notre esprit. C’est le discours de la modélisation qui privilégie ce que Paul VALERY appelle dans Monsieur Teste « la machine » de langage. Ce sont les habitudes langagières qui consistent à inventer des codes d’écriture et de lecture servant de règle à toutes les communautés doxiques dans leur rapport avec le monde. Ce langage apparaît à travers l’utilisation des formes génériques et figées comme le stéréotype, le lieu commun, le cliché, le préjugé, l’idée reçue. La thèse essaie de mettre en exergue les stratégies de dénonciation d’une telle forme de discours dans le roman de Nathalie Sarraute. Elle passe en revue l’énonciation et la dénonciation des stéréotypes qui se divisent en stéréotypes de pensées et en stéréotypes de langue. / The thesis deals with the problem of repetition in speech. The language of repetition is the doxa, word that we used in the thesis as the generic term that encompasses this complex reality that Nathalie Sarraute denounces in his work by attacking the discursive realism. He is studying the set language that expresses frozen realities in a literary corpus. It is a language that relies on a prototypical reference system. The referent is either an object, either a property or a reportable process wich realists consider that there are outside our mind. It is the speech of modeling that privileges what Paul VALERY call in Mr tests the "machine language ". These are the language habits which consist in inventing of the codes of writing and reading rule for all doxa communities in their relation to the world. This language appears through the use of generic and frozen forms as the stereotype, the common place, the cliché, the prejudice, the received idea. The thesis tries to highlight strategies for the reporting of such a form of speech in the novel to Nathalie Sarraute. She will review the enunciation and the denunciation of the stereotypes that divide in stereotypes of thoughts and language stereotypes

Phase change of the water in the soil skeleton under cold climate conditions (also known as frost action in soils) affects soil properties and can be responsible for serious alterations in a soil body; causing damages (due to the volumetric expansion known as frost heave) to structures on or below the ground surface such as foundations, roads, railways, retaining walls and pipelines, etc. In order to improve the current design methods for roads against frost action, the Swedish Transport Administration (Trafikverket) has initiated a research program. The main goals of the program are to revise the existing frost heave estimation methods and improve the frost susceptibility classification system for subgrade soils. Literature was reviewed to gather the details of different freezing test equipment around the world and to identify common trends and practices for laboratory freezing tests. Based on the literature review and the collaboration with the University of Oulu, Finland an experimental apparatus was assembled for studying frost action in the laboratory. A detailed description of the experimental apparatus is given. Top to down freezing of specimens (of 10cm height and diameter) can be monitored while keeping track of water intake, vertical displacements (heave) and the temperature profile within the sample. Loads can be applied at the top of the sample to study the effects of overburden. Moreover, the test setup was modified with a camera system to have the option of recording the experiments. Disturbed samples of two different soil types were tested. Experiments with fixed and varying temperature boundary conditions were conducted to assess the validity of the assumptions for the frost heave estimation methods currently in use in Sweden. To this end, a qualitative relationship between frost heave and heat extraction rates based on theoretical equations was established. It was shown that there is a significant difference between the preliminary findings of the experimental work and the current system being used in Sweden to quantify heave. Image analysis techniques were used on two experiments that were recorded by the camera system. Image recording and correlation analyses provided detailed information about frost front penetration and ice lens formation(s) under varying temperature boundary conditions. Thawing has also been regarded in further studies. Results of the image analyses were compared to readings from conventional displacement measurements during the same test. Significant agreement between the results of image analyses and displacement measurements has been found. Image analysis was shown to be a viable method in further understanding of frost heave mechanisms. Shortcomings and disadvantages of utilizing the theoretical equations as well as the image analysis techniques were discussed. Potential remedies for overcoming the drawbacks associated with each approach are suggested. The work is concluded by discussing the potential improvements, planned upgrades (addition of pore pressure transducers) and the future experiments to be conducted.

Magister Legum - LLM / Several international instruments relating to the forfeiture of assets derived through unlawful means have been developed in the last decade. These relate to both civil and criminal forfeiture proceedings. Nevertheless, the processes of tracing the assets and having them forfeit to the State present formidable obstacles to justice authorities enforcers around the world. The fact of the matter is that the advent of the internet has made it easier for money launderers to camouflage the nature and the physical locality of their ill-got gains. This has made it all the more necessary for states and financial institutions to co-operate more closely in hitting the criminals where it hurts most – their pockets. However, the international structures that provide for mutual legal assistance procedures are drafted in broad terms or in guideline-form. Most of the books and journal articles dealing with money laundering devote scant attention to this very important aspect of combating transnational economic criminality. In most of the literature, this topic is simply avoided. This paper, which confines itself to civil recovery proceedings, strives to determine first, what international mechanisms are available for obtaining information located abroad that could be used for domestic civil forfeiture, and second, to identify some of the most intractable problems encountered by justice authorities in their attempts to attach property situated abroad. The idea is to identify the principal point of discordance, and to suggest ways in which the international instruments governing civil forfeiture could be amended so as to make them more user friendly.

Ce travail de thèse porte sur l’étude de l’effet du traitement par champs électriques pulsés (CEP) sur l’amélioration de la congélation des tissus végétaux. Pour l’ensemble de notre étude, nous avons démontré que l’effet des champs électriques pulsés est complexe. Le prétraitement entraîne une électroperméabilisation des membranes. Les analyses calorimétriques ont mis en évidence que l’électroperméabilisation conduit à une augmentation de la teneur en eau liée. Les transferts de matière entre les milieux intra et extracellulaires sont intensifiés. Cela conduit à une modification dynamique de la composition des deux compartiments au cours de la congélation. En effet, les essais réalisés sur le cryo-pressage assisté par CEP démontrent que les températures de fusion sont plus basses et que le jus récupéré est beaucoup plus concentré. Il a été constaté que le temps de congélation d’un échantillon soumis préalablement à un prétraitement par champs électriques pulsés est sensiblement plus court que celui d’un échantillon sans prétraitement. D’autre part, l’électroperméabilisation facilite les transferts de matière avec le milieu extérieur. Le prétraitement par CEP accélère notamment l’imprégnation des tissus végétaux par des cryoprotectants, l’évaporation de l’eau libre et la sublimation de l’eau congelée. Finalement, le prétraitement par champs électriques pulsés induit des modifications de la structure des échantillons, de leur composition et influence favorablement les transferts couplés de masse et d’énergie. / This work is focused on the study of the effects of pulsed electric fields (PEF) on the improvement of plant tissues freezing. These studies have demonstrated that the effects of the PEF are rather complex. The PEF treatment results in membrane electro-permeabilization. Calorimetric analyses showed that the electro-permeabilization leads to an increase in bound water content. It also results in acceleration of mass transfer processes between intra- and extracellular parts of a tissue. The dynamic modification of the composition of these two parts during the freezing was observed. Experimental tests using the PEF-assisted cryo-pressing demonstrated that the melting temperatures were lower and that the extracted juice was much more concentrated as compared to untreated tissues. Moreover, the PEF-treatment allowed significant decreasing of freezing time. Furthermore, the electro-permeabilization facilitates the mass transfer with the external medium. The PEF treatment accelerates the impregnation of plant tissues by cryoprotectants, evaporation of free water and sublimation of frozen water. Finally, the treatment by PEF induces changes in the structure of the samples, their composition and positively influences both the mass and energy transfers.

The thesis presents work regarding amphiphilic molecules associated in aqueous solution or at the liquid/solid interface. Two main topics are included: the temperature-dependent behavior of micelles and the adsorption of dispersants on carbon nanotube (CNT) surfaces. Various NMR methods were used to analyze those systems, such as chemical shift detection, spectral intensity measurements, spin relaxation and, in particular, self-diffusion experiments. Besides this, small angle X-ray scattering (SAXS) was also applied for structural characterization.   A particular form of phase transition, core freezing, was detected as a function of temperature in micelles composed by a single sort of Brij-type surfactants. In mixed micelles, that phase transition still occurs accompanied by a reversible segregation of different surfactants into distinct aggregates. Adding a hydrophobic solubilizate shifts the core freezing point to a lower temperature. Upon lowering the temperature to the core freezing point, the solubilizate is released. The temperature course of the release curves with different initial solubilizate loadings is rationalized in terms of a temperature-dependent loading capacity.   The behavior of amphiphilic dispersant molecules in aqueous dispersions of carbon nanotubes (CNTs) has been investigated with a Pluronic-type block copolymer as frequent model dispersant. Detailed dispersion curves were recorded and the distribution of the dispersant among different available environments was analyzed. The amount of dispersed CNT was shown to be defined by a complex interplay of several factors during the dispersion process such as dispersant concentration, sonication time, centrifugation and CNT loading. In the dispersion process, high amphiphilic concentration is required because the pristine CNT surfaces made available by sonication must be rapidly covered by dispersants to avoid their re-attachment. In the prepared dispersions, the competitive adsorption of possible dispersants was investigated that provided information about the relative strength of the interaction of those with the nanotube surfaces. Anionic surfactants were found to have a strong tendency to replace Pluronics, which indicates a strong binding of those surfactants.   CNTs were dispersed in an epoxy resin to prepare nanotube-polymer composites. The molecular mobility of epoxy was investigated and the results demonstrated the presence of loosely associated CNT aggregates within which the molecular transport of epoxy is slow because of strong attractive intermolecular interactions between epoxy and the CNT surface. The rheological behavior is dominated by aggregate-aggregate jamming. / <p>QC 20180103</p>