Este estudo investiga o Módulo de Young (Módulo de Elasticidade) em amostras de osso cortical oriundas de uma mesma região da tíbia bovina depois de submetidas a congelamentos e descongelamentos sucessivos. As amostras foram coletadas da face caudal do terço médio da diáfise de tíbias bovinas e depois submetidas a testes de flexão em três pontos e ensaios de ruptura, obedecendo à norma ASTMD790M86ε1. Nesse experimento, 20 pares de amostras de ossos corticais foram retirados de 20 tíbias bovinas, cada amostra medindo 2 mm x 4 mm x 40 mm, aproximadamente. Todos os testes foram realizados à temperatura controlada (21 graus Celsius), e as condições de ensaio foram as mesmas durante os testes. As amostras foram identificadas e divididas em dois grupos experimentais: Grupo A: as amostras foram conservadas (em sacos plásticos) a - 20 graus Celsius (submetidos a congelamentos e descongelamentos sucessivos por 50 vezes: uma vez ao dia durante 50 dias). Esses descongelamentos produziram 15 ensaios de flexão, sendo que o primeiro foi realizado com as amostras ainda frescas mantidas em geladeira a 4 graus Celsius. Após os 50 descongelamentos foram levados até a ruptura. Grupo B: as amostras foram conservadas frescas (em sacos plásticos) a 4 graus Celsius em geladeira aguardando o tempo para que os ensaios do grupo A fossem concluídos e, posteriormente fez-se o teste de ruptura. Importantes cuidados foram tomados. Depois de cada descongelamento, as amostras foram analisadas e comparadas com as amostras frescas tanto para os ensaios de flexão em três pontos como para os ensaios de ruptura. Observamos que o congelamento não alterou de modo significativo as propriedades mecânicas destes ossos, pois não foi encontrada nenhuma diferença significativa entre o comportamento dos dois grupos testados. Isso implica que, congelando e estocando mesmo por longos períodos, as propriedades mecânicas não se alteram tanto nos ensaios de flexão em três pontos como nos ensaios de ruptura. Com respeito às diferenças observadas no dia a dia, as alterações do primeiro dia até o último dia não foram significativas / The present study was conducted to investigate the Young Module (Elasticity Module) in cortical bone samples submitted to successive freezing and thawing and then assayed in flexion tests at three points and in rupture tests according to the norms of ASTMD790M86ε1. Twenty pairs of cortical bone samples, each measuring approximately 2 x 4 x 40 mm, were collected from the same region of the caudal surface of the middle third of the diaphysis of 20 bovine tibiae and divided into two experimental groups: Group A: consisting of 20 cortical bone samples stored at – 20 Celsius degrees in plastic bags and submitted to successive freezing and thawing 50 times once a day for 50 days. These thawing episodes produced 15 flexion assays. After the 50 thawing episodes, the samples were tested until rupture. Group B: consisting of 20 cortical bone samples stored at 4 Celsius degrees in plastic bags in a refrigerator until the time when the assays of group A were concluded and then submitted to the rupture test. No statistically significant variation in the Young Module was observed after the flexion test at three points performed for Group A. The values of rupture tension also did not differ significantly between groups A and B. We observed that freezing did not cause a significant change in the mechanical properties of these bones, indicating that freezing and storage of these bones even for long periods of time does not alter their mechanical properties in flexion tests at three points or in rupture assays

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No. of bitstreams: 1 carolinamarinhodeassuncao.pdf: 1072103 bytes, checksum: 9a380e0469f7cdaa891cb6b94e580479 (MD5) Previous issue date: 2016-03-28 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Apesar da grande aplicação do sêmen congelado na bovinocultura, a criopreservação ainda resulta em considerável diminuição da viabilidade e fertilidade espermática. Diversos fatores são responsáveis por essa perda, sendo importante ressaltar os danos causados ao espermatozoide pelo estresse oxidativo. O objetivo do trabalho foi avaliar o efeito antioxidante resveratrol na criopreservação de sêmen bovino. Foram utilizados oito touros holandeses selecionados previamente por exame andrológico. O sêmen foi diluído em meio Tris-gema-glicerol e divididos nos grupos: R0 (controle- sem antioxidante), R1 (50 μM de resveratrol), R2 (100 μM de resveratrol) e R3 (1000 μM de resveratrol). Os espermatozoides após o descongelamento foram avaliados através da análise de motilidade e vigor espermáticos por microscopia de contraste de fase, parâmetros cinéticos por sistema automatizado (CASA), integridade de membrana plasmática e acrossomal, função mitocondrial e fertilidade in vitro. Os dados foram analisados por ANOVA e as médias foram comparadas pelo teste de Tukey-Krammer e Student-Newman-Keuls ao nível de significância de 5% através dos programas Statistical Analysis System (SAS Institute, Cay, NC, USA) e Graph Pad Prism versão 5 (Graph Pad Software, California, Estados Unidos). Na análise de motilidade do sêmen por microscopia óptica observou-se maior média (P<0,05) do tratamento R1 em relação a R3, não sendo estes diferentes (P>0,05) do controle e de R2. Entretanto, os resultados da análise de motilidade progressiva pelo CASA mostraram que o tratamento com resveratrol 50 μM apresentou melhor (P<0,05) resultado em relação ao controle e outros tratamentos. Os dados dos parâmetros cinéticos do CASA também revelaram um número maior de espermatozoides com trajetória linear no grupo R1. Há também mais células com membrana plasmática integra no grupo tratado (R1) em relação ao controle. Na análise de função mitocondrial e na produção in vitro de embriões não houve diferença entre controle e tratamento (P>0,05). Conclui-se que o resveratrol na concentração de 50 μM protege a membrana plasmática de células espermáticas e melhora parâmetros cinéticos do sêmen sem alterar a capacidade fecundante do espermatozoide. / Despite the wide application of frozen semen in livestock, cryopreservation yet results in decrease in viability and fertility of sperm. Several factors are responsible for this loss as injuries caused on sperm by oxidative stress. The aim of the study was to evaluate the antioxidant effect of resveratrol on cryopreservation of bovine sperm. We used eight Holstein bulls selected previously by andrological exam. Semen was diluted in Tris-yolk-glycerol extender and distributed in groups: R0 (control - no antioxidant), R1 (50 μM resveratrol), R2 (100 μM resveratrol) and R3 (1000 μM resveratrol). Motility and vigorous thawed bull sperm were evaluated by phase contrast microscopy and kinetics parameters by an automated system (CASA). Plasmatic and acrosomal membrane integrity, mitochondrial function, and in vitro fertilization were also evaluated in thawed sperm. The data were analyzed by ANOVA and averages were compared by Tukey-Krammer and Student-Newman-Keuls tests by the Statistical Analysis System (SAS Institute, Cay, NC, USA) and Graph Pad Prism versão 5 (Graph Pad Software, California, Estados Unidos). The level of 5% was considered significant. With optical microscopy was observed higher sperm motility in treatment R1 than R3, and they were not different (P>0.05) to control and R2. However, the results of progressive motility analysis by CASA showed that treatment with 50 μM resveratrol had better (P <0.05) results than control and other treatments. The data of the kinetic parameters of CASA also revealed greater (P <0.05) number of spermatozoa with linear trajectory in R1 treatment. There is also more (P <0.05) cells with plasma membrane intact in R1 compared to the control. In mitochondrial function analysis and in vitro embryo production no difference was found between treatment and control (P>0.05). We conclude that the resveratrol 50 μM concentration protects the sperm cell plasmatic membrane and improves kinetic parameters without affect fertilization potential of spermatozoa.

Made available in DSpace on 2014-08-20T14:37:55Z (GMT). No. of bitstreams: 1 dissertacao_carine_dahl_ corcini.pdf: 419232 bytes, checksum: 05d064069666c9b2d7ee37c1f565b4c2 (MD5) Previous issue date: 2008-04-18 / Artificial insemination (AI) in swine with frozen semen presents lower reproductive performance than AI with cooled semen. Such inefficiency can be attributed to many factors, especially to the semen extenders and individual boar effects, since boars may have different protein content in their seminal plasma. The objective of this study was to evaluate the protein content of distinct portions of the ejaculate of boars, prior to freezing, and the association between the presence of the proteins in the seminal plasma and parameters of semen quality post-thawing, to identify biochemical markers potentially associated with semen freezability in different boars and portions of the ejaculate. The sperm-rich portion of the ejaculate was fractioned in two samples, which were frozen in an extender containing 5% dimethylacetamide as a penetrating cryoprotectant. The protein content of the seminal plasma was evaluated through unidimensional electrophoresis and associated with sperm motility and membrane integrity, pre-freezing and post-thawing, and to sperm morphology and acrossome integrity post-thawing. Inter-boar analyses were conducted, adjusting for individual effects, as well as intra-boar analyses, which were stratified by boar. The first portion of the ejaculate, consisting of the first collected 10 mL, presented better post-thawing semen quality than the second portion. Nine proteins present in the seminal plasma presented significant association with parameters of semen quality (P < 0.05), in both inter and intra-boar analyses. Among them, two proteins, having molecular weight of 28 and 100 kDa were associated, respectively, with post-thawing sperm motility and both pre-freezing and post-thawing sperm membrane integrity. Thus, such proteins are potential biochemical markers for boar semen quality. / A inseminação artificial (IA) em suínos com sêmen congelado apresenta índices de desempenho reprodutivo insatisfatórios, em comparação com a IA com sêmen resfriado. Entre outros fatores, esta ineficiência pode ser atribuída aos diluentes e à variação entre os machos doadores de sêmen, que podem apresentar diferente conteúdo de proteínas no plasma seminal. O objetivo deste trabalho foi avaliar o conteúdo protéico de diferentes porções do ejaculado de suínos, antes destas serem submetidas ao congelamento, e a associação entre a presença de proteínas identificadas no plasma seminal e indicadores de qualidade seminal pósdescongelamento, visando a identificação de marcadores bioquímicos associados com a congelabilidade do sêmen de diferentes machos e frações do ejaculado. A porção do ejaculado rica em espermatozóides foi fracionada em duas amostras, as quais foram congeladas em diluente contendo 5% de dimetilacetamida como crioprotetor interno. O conteúdo protéico do plasma seminal foi avaliado por eletroforese unidimensional e associado com motilidade e integridade da membrana espermática pré e pós-congelamento, e morfologia espermática e integridade de acrossoma pós-congelamento. Foram conduzidas análises inter-machos, nas quais o efeito individual foi ajustado, e intra-machos, nas quais as análises foram estratificadas para cada macho. A primeira porção do ejaculado, consistindo dos primeiros 10 mL coletados, apresentou melhores indicadores de qualidade seminal pós-descongelamento, em comparação com a segunda porção do ejaculado. Nove proteínas presentes no plasma seminal apresentaram associação significativa com parâmetros de qualidade do sêmen congelado, tanto na análise inter-machos, como na intra-machos. Dentre estas nove proteínas, duas dela, que possuem peso molecular de 28 e 100 kDa foram associadas, respectivamente, com a motilidade pós-descongelamento e com a integridade da membrana espermática précongelamento e pós-descongelamento (P < 0,05), sendo, portanto, potenciais candidatas a marcadores bioquímicos para qualidade de sêmen de suínos.

Lignin is a key component of plant secondary cell walls, providing strength to the plant and allowing water transport. Lignin is a polymer of monolignols that are synthesized in the cell and transported into the cellulose rich cell wall. The primary goal of this thesis is to understand the mechanism(s) of monolignol deposition during xylogenesis. The currently accepted theory is that monolignols are exported by Golgi-mediated vesicle delivery to the secondary cell wall. When this theory was re-examined using cryofixed developing pine, quantitative autoradiography showed that monolignols did not accumulate in Golgi but were rapidly translocated from cytosol to cell wall. This suggests alternative mechanisms, such as membrane transporters, work in monolignol export. ATP binding cassette (ABC) transporters were chosen because they transport other secondary metabolites and some ABC transporter encoding genes are highly expressed in lignifying cells. Four candidate ABC transporters were selected in Arabidopsis (ABCB11, ABCB14, ABCB15 from the ABCB/MDR subfamily and ABCG33 from the ABCG/PDR subfamily) and shown to have overlapping, high vasculature expression patterns. Mutants with T-DNA insertions in single ABC transporter genes had no change in lignification of inflorescence stems. However, a reduced polar auxin transport phenotype was detected in mutants of ABCB11, ABCB14 and ABCB15. An additional approach was the use of inhibitors of ABC transporters. A new assay, which was developed to quantify lignification in primary xylem of Arabidopsis roots, demonstrated that ABC inhibitors did not change lignin deposition. Monolignols are exported and polymerized in the polysaccharide matrix of the cell wall, which includes hemicelluloses that may organize monolignols during polymerization. Since diverse lignified cell types are enriched in either G- or S-lignin, I hypothesized that this pattern could reflect different hemicellulose distributions, which was examined using antibody labeling of xylans or mannans in hybrid poplar xylem. While xylans were generally distributed in all secondary cell walls, mannans were enriched in fibers but not in the ray and vessel walls. In summary, during secondary cell wall deposition, monolignols are exported by unknown transporter(s) rather than Golgi vesicles. In developing poplar wood, the monolignols are deposited into diverse hemicellulose domains in different cell types. / Science, Faculty of / Botany, Department of / Graduate

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work analyzes a spin glass (SG) model with cluster in two versions: a classic version with Ising spins and in a fermionic version with spin operators. In this model, the basic entities are correlated clusters that interact each other disorderedly (intercluster interaction). It is also considered short-range interactions among spins belonging to the same cluster (intracluster interaction), which can be ferromagnetic (FE) or antiferro- magnetic (AF). Disordered intercluster interactions are analytically calculated by using the framework of Parisi one-step replica symmetry breaking. After this treatment, we get an effective single cluster model solved by exact diagonalization. The fermionic version of the model can introduce quantum fluctuations by means of a transverse magnetic field Γ. As a result, the linear susceptibility χ has a cusp at the transition temperature Tf and the specific heat Cv has a broad maximum at temperature T* about 20% above Tf . However, for Γ sufficiently high, this difference is greater. This behavior is observed by some authors for the compound LiHoxY1-xF4 at low concentration. Furthermore, the fermionic SG model with cluster in the grand canonical ensemble (where the chemical potential μ introduces charge fluctuations) is used to investigate the mechanisms responsible for the inverse freezing (IF). In this analysis, for a certain region of μ, a reentrance related to the inverse freezing arises. However, the increase of the FE intracluster interactions J0 can take the tricritical point to lower T, introducing a second-order IF transition. On the other hand, the Γ destroys gradually the inverse freezing. The necessary mechanisms for the emergence of inverse freezing transition are also studied using the cluster SG model in a classic version with Ising spins. This study is firstly conducted considering only firstneighbors intracluster interactions AF and in a second moment considering intracluster interactions among second neighbors, where it is possible to introduce intracluster geometrical frustration. The presence of antiferromagnetic intracluster interactions decreases the total magnetic moment of the clusters, leading to a PM phase with low entropy, favoring the appearance of inverse freezing. Moreover, the presence of geometrical frustration is contrary to the emergence of inverse freezing. / Este trabalho analisa um modelo de vidro de spin (VS) com clusters em duasversões: uma versão clássica com spins de Ising e uma versão fermiônica com operadores de spins. Neste modelo, as entidades básicas são clusters correlacionados que interagem entre si de modo desordenado (interação intercluster). Considera-se também interações de curto-alcance entre momentos magnéticos pertencentes ao mesmo cluster (interação intracluster), que podem ser ferromagnéticas (FE) ou antiferromagnéticas (AF). As interações desordenadas intercluster são calculadas analiticamente através do método das réplicas com aproximação de um passo de quebra de simetria de réplicas. Após o tratamento, chega-se a um modelo efetivo de um único cluster resolvido por diagonalização exata. A versão fermiônica do modelo pode introduzir flutuações quânticas por meio de um campo magnético transverso Γ. Como resultados, a curva da susceptibilidade magnéticaΓ em função da temperatura T apresenta um pico agudo na temperatura de transição Tf e a curva do calor específico Cv em função de T apresenta um máximo arredondado à temperatura T* cerca de 20% acima de Tf . Porém, para um Γ suficientemente alto, esta diferença é muito maior, comportamento que é observado por alguns autores para o composto LiHoxY1-xF4 a baixas concentrações. Além disso, o modelo VS fermiônico com clusters no ensemble grão-canônico (onde o potencial químico μ introduz flutuações de carga) é usado para investigar os mecanismos responsáveis pelo congelamento inverso. Nesta análise, para uma certa região de μ, uma reentrância relacionada ao congelamento inverso surge. Entretanto, o aumento das interações FE intracluster J0 pode levar o ponto tricrítico para valores de T mais baixos, fazendo com que uma transição reentrante de segunda-ordem apareça. Por outro lado, o efeito de Γ é destruir o congelamento inverso gradativamente. Os mecanismos necessários para o surgimento da transição congelamento inverso também são estudados através do modelo de VS com clusters em uma versão clássica utilizando spins de Ising. Este estudo é realizado primeiramente considerando somente primeiros vizinhos intracluster AF e em um segundo momento considerando interações intracluster entre primeiros e segundos vizinhos, onde é possível introduzir frustração geométrica intracluster. A presença de interações antiferromagnéticas intracluster diminui o momento magnético total dos clusters, levando a uma fase PM de baixa entropia, favorecendo o aparecimento de congelamento inverso. Por outro lado, a presença de frustração geométrica é contrária ao surgimento de congelamento inverso.

Ce travail de recherches se situe dans le cadre de l’ANR VBD2012-ECO-construction par le Recyclage du Béton (ECOREB). Il vise à lever certains verrous scientifiques afin de rendre possible l’utilisation des granulats issus de la démolition/déconstruction pour élaborer de nouveaux bétons pour le bâtiment. L’ANR ECOREB est en relation avec le PN RECYBETON. Les deux projets interagissent fortement.Cette étude a pour objectif d’évaluer la durabilité des bétons recyclés vis-à-vis du gel/dégel modéré sans sels de déverglaçage. Les bétons ont été élaborés en faisant varier : le taux d’incorporation des granulats recyclés (GR) l’état de saturation des gravillons tout en maintenant la même classe de consistance S4 et la classe de résistance de type C35/45. Un agent entraîneur d’air a été introduit afin d’obtenir des bétons conformes à l’EN 206-1 avec deux teneurs en air occlus 4% et 6%.Dans un premier temps, les propriétés physiques et mécaniques des granulats recyclés (GR) ont été étudiées et comparées à celles des granulats naturels (GN). Les GR manifestent une capacité d’absorption d’eau dix fois supérieure à celle des GN, une résistance mécanique deux fois inférieure et une résistance au gel deux fois inférieure. Cependant ils sont classés non gélifs de catégorie Fdéclaré.. Les faibles propriétés des GR comparées à celles des GN s’expliquent par la présence de l’ancienne pâte de ciment qui entoure les grains originaux et qui est caractérisée par une forte porosité et par un fort réseau de fissures connecté créé lors du concassage du béton parent.Les propriétés physiques (porosité et coefficient d’absorption d’eau) de transfert (conductivité thermique, résistivité électrique et perméabilité) et mécaniques sont fortement impactées par l’incorporation des granulats recyclés de part l’augmentation de la porosité capillaire essentiellement et du réseau des fissures présentes dans les gravillons recyclés. Les relations établies entre les propriétés mécaniques et les propriétés physiques et de transfert ont été établies. L’applicabilité des Euro codes égalementLes formulations avec un taux d’air occlus de 4% sont de classe C30/37 pour tous les taux d’incorporations alors qu’une diminution notable des résistances mécaniques à la compression est observée pour un taux d’air occlus de 6% : le béton de référence devient de classe C16/20. L’incorporation des GR affecte la résistance au gel/dégel des bétons. En utilisant les indicateurs préconisés par la norme NFP 424, le béton sans agent entraineur d’air atteint les critères recommandés au 75ème cycle lorsqu’il est élaboré avec 100% de GR et au 125ème cycle quand seuls les GN sont utilisés. L’entraineur d’air améliore la tenue au gel des bétons. Nous remarquons que les bétons C35/45 30R-30R (30% en volume d’incorporation) avec 4% d’air entrainé présentent le comportement ressemblant à celui du béton référence et respecte les critères de la résistance préconisé par la norme NF P 18-424 et l’EN 206-1.Ce travail a permis également de mettre en place d’autre indicateurs performantielles pour estimer la résistance au gel/dégel des bétons à granulats recyclés. / Development in many sectors has negative environmental effects. In construction sector, there are millions of tonnes of construction and demolition waste (CDW) every year. This CDW has a significant damage on the environment and may endanger its sustainability. To find a conceivable solution for CDW and to preserve the natural resources, particularly the non-renewable ones, worldwide researches on recycled aggregates have been increased in order to investigate their revalorization possibilities in concretes.As many developed countries, France also has introduced legislations and strategies to reduce the environmental effects of CDW. Corresponding to problem of CDW, there are two national project called PN-RECYBETON and ANR VBD2012-ECOREB that deal with how to provide concretes for building field using aggregates provided from CDW.This work aims to determine the durability of recycled aggregate concrete by freeze/thaw cycles. Four types of concrete were prepared by varying the replacement ratio of natural aggregates (NA) by recycled one (RA). The volumetric substitutions rates are respectively 0%, 33%, 55% and 100%, while the concretes mix design were adjusted in order to achieve the same consistency class of S4. Furthermore, we also studied the durability of these concretes varying the air content through an air entraining agent.After characterization of physical and mechanical properties of NA and RA, we found that the water absorption capacity of RA is 10 times greater than that of NA due to a low density. Moreover, the RA presents poor mechanical résistance by LA, MDE and freezing action.These poor performances of RA can be explained by the existence of pores and crack in old cement paste that provided during production process. The microstructure of RA was analyzed by SEM.Regarding to the influence of RA in mix design, with total substitution the density of hardened decrease 17% while the porosity become two times greater than those of natural concrete.In addition, the mechanical properties of studied concretes mix design decreases through the incorporation of RA. Regarding to the transfer properties, the gas permeability of the concrete 100% substitution is 2 times higher than that of reference one. On the other hand, the electric resistivity decreases with increasing of RA content.The Air-Entraining agent has a significant effect on the compressive and the splitting tensile strengths. It is observed that with 6% of air content the mentioned mechanical properties decrease drastically (a diminution higher than 50%). The increase of RAC content in the mixtures decreases their freezing/thawing resistance.The introduction of Air-Entraining agent improves the freezing/thawing resistance of concrete. The air-entrained concrete with 50% and 100% of RA present the poor performance than that of reference concrete via the studied durability indicators. Moreover, the air-entrained concrete C35/45 30R-30R with 4% and 6% of air content show the similar performance as air-entrained control concrete.

La congélation artificielle des terrains est une technique d'imperméabilisation et de renforcement des terrains régulièrement employée dans le génie civil et l'industrie minière. Dans un objectif de prédiction fiable de l'évolution de la congélation dans le milieu poreux, cette recherche propose deux nouveaux modèles numériques permettant la simulation du problème global de la congélation artificielle des terrains. Un premier modèle a pour objectif la représentation des mécanismes couplés thermo-hydrauliques associés à la congélation du matériau tandis qu'un deuxième modèle se concentre sur l'estimation des échanges de chaleur entre un puits de congélation et le terrain environnant. Le modèle thermo-hydraulique, en plus d'être cohérent sur le plan thermodynamique, a été vérifié à la fois par rapport à des solutions analytiques et par rapport à des résultats expérimentaux obtenus à grande échelle en conditions d'écoulements importants. Le modèle puits-terrain adopte une approche innovante par rapport à la bibliographie. Il permet de déterminer les conditions aux limites des modèles de congélation des terrains, difficiles à connaître en pratique, et d'optimiser les conditions opératoires du système grâce à des temps de simulation limités. De par les hypothèses considérées, leur fiabilité et leur praticité d'utilisation, ces deux modèles sont particulièrement adaptés à des sites industriels comme celui de la mine d'uranium de Cigar Lake (Canada) qui présente deux contraintes majeures : la présence potentielle d'écoulements importants et la forte hétérogénéité des terrains à congeler. Dans de tels contextes, des applications d'utilisation conjointe des deux modèles ou non sont présentées par rapport à des cas simples et au cas industriel de Cigar Lake. Ils peuvent ainsi être employés pour prédire l'évolution de la congélation dans le terrain en tenant compte des interactions thermo-hydrauliques, pour optimiser le système de congélation, ou encore pour évaluer l'impact sur la progression des zones congelées de conditions géologiques, hydrogéologiques et opératoires particulières. / Artificial ground freezing is a ground sealing and reinforcement technique regularly used in civil and mining engineering. In order to reliably predict the freezing evolution in the porous medium, this research offers two new numerical models allowing the simulation of the global problem of artificial ground freezing. A first model aims at representing the thermo-hydraulic coupled mechanisms associated with the material freezing while a second model focuses on the estimation of heat transfers between a freeze pipe and the surrounding ground. The thermo-hydraulic model, in addition to being thermodynamically consistent, has been verified both with respect to analytical solutions and large- scale experimental results obtained under conditions of high water flow velocity. The pipe-ground model adopts an innovative approach compared with literature. It allows to determine the boundary conditions of the ground freezing models, not readily available in practice, and to optimize the operating conditions of the system thanks to limited simulation times. By the considered assumptions, their reliability and their practicality, these two models are particularly well adapted to industrial sites like the uranium mine Cigar Lake (Canada) which presents two major constraints: the potential presence of high seepage-flow velocities and the strong ground heterogeneity. In these contexts, applications of the two models, jointly used or not, are presented with respect to simple cases and to the industrial case of Cigar Lake. They can be employed to predict the freezing evolution in the ground considering the thermo-hydraulic interactions, to optimize the freezing system, or to evaluate the impact of specific geological, hydrogeological and operating conditions on the freezing progress.

Magister Legum - LLM / The aim of this research paper is to examine the legal framework for the recovery of corruptly-acquired assets, with particular emphasis on the Nigerian situation. Its primary focus is a detailed examination of the legal mechanisms for the recovery of such assets in the context of international asset recovery. Despite the success of the Nigerian government in recovering the Abacha loot,8 siphoning off of public funds by public office holders continues, and charges of fraud persist against top bank executives alleged to have converted depositors&rsquo; funds fraudulently. The prevailing criminal or conviction-based forfeiture mechanism in Nigeria appears inadequate to deal effectively with these situations. The need to enhance capacity through the adoption of civil or non-conviction based forfeiture laws therefore becomes imperative. / South Africa

Magister Legum - LLM

Notre thèse porte sur l’étude linguistique contrastive de la référence aux couleurs dans les proverbes à partir d'un corpus de 208 proverbes recueillis en France et en Irak. Nous étudierons la manière dont les couleurs sont exprimées dans les deux langues (catégories grammaticales, structure grammaticale et prosodique des énoncés, outils rhétoriques appliqués aux couleurs pour renforcer leur valeur expressive), ainsi que le rapport des locuteurs à l'usage des couleurs dans les proverbes qu'ils utilisent. Nous essayerons également d'explorer dans les deux langues les différences liées à l'époque où le proverbe a été le plus utilisé, ainsi que le degré de connaissance des proverbes selon l'âge, le sexe, la profession et la région du locuteur. La langue française, ainsi que le dialecte irakien contiennent une grande proportion de mots indiquant la couleur dans les proverbes. Et c’est la connotation de ces mots qui est à l’origine de la difficulté de compréhension. De plus, selon les pays, les cultures et les époques, les couleurs revêtent des significations différentes, parfois aux antipodes de celles des cultures voisines, comme le blanc, associé en occident et dans les pays arabes (comme en Irak) à la pureté, alors qu’il est lié au deuil dans la plupart des pays asiatiques. Grâce à la langue, comme nous le savons, l’homme peut communiquer, échanger les informations, les idées et les sentiments. En d’autres termes, les parleurs peuvent exprimer ce qu’ils veulent exprimer, ce qu’ils veulent dire et les auditeurs peuvent recevoir les informations. Cependant, dans la communication, il n’est pas toujours facile de comprendre complètement et exactement ce qui est dit et écrit, parce que le sens du mot est compliqué et sophistiqué. Le même mot, utilisé dans ces différentes situations, aura différentes significations. Les mots indiquant la couleur se heurtent aux mêmes problèmes. Fonctionnant comme une unité isolée, le proverbe est une combinaison de mots tirés du vocabulaire général de chaque langue. Nous considérons les mots indiquant la couleur dans les proverbes et les locutions proverbiales comme l’objet de notre étude parce que la couleur est partout dans notre vie : la couleur des plantes et des animaux, la couleur du ciel et de la terre, la couleur des aliments, mais aussi parce que les proverbes constituent une source de vocabulaire riche pour ceux qui apprennent la langue. Les proverbes portent divers champs sémantiques et ils reflètent bien les difficultés culturelles liées à l’apprentissage du français en Irak. En outre, nous essayerons de prouver, à travers des transformations et des manipulations, que ces proverbes peuvent être figés. Une étude approfondie de ces traits sémantiques et syntaxiques nous a paru de première nécessité pour rendre compte de l'existence du figement dans les proverbes, phénomène linguistique à la fois très important et très complexe. Par ailleurs, la comparaison critique entre ces deux langues, le français et l’arabe en l’occurrence, affirme que ce phénomène du figement n’est qu’un fait linguistique universel, et révèle que chaque langue a ses propres mécanismes de figement. Nous pouvons noter que du point de vue sémantique, le sens des proverbes n’est pas calculé selon les règles de la compositionalité ; autrement dit, le sens global des proverbes n’est pas l’addition du sens des éléments qui les composent. / Our thesis concerns the contrastive linguistic study of The reference to colors in the proverbs from a corpus of 208 proverbs collected in France and in Iraq. We shall study how the colors are expressed in both languages (word classes, grammatical and prosodic structure of the statements, the rhetoric tools applied to colors to strengthen their meaning value) as well as the link of the speakers for colors in the proverbs they use. We shall also try to explore in both languages the differences related to the period when the proverb was the most used as well as in the degree of knowledge of the proverbs according to age, sex, profession and the region of the speaker. The French language as well as the Iraqi dialect contain a big proportion of words indicating the color in the proverbs. And it is the connotation of these words that is the origin of the difficulty of understanding. Furthermore, according to countries, cultures and times, the colors take on different meanings sometimes to the antipodes of those of the nearby cultures like the colour white, associated in the West and in Arab countries to purity, while it is refers to mourning in most of the Asian countries. Thanks to the language, as we know it, the man can communicate, exchange information, ideas and eelings. In other words, the speakers can express what they want to express, what they want to sayand the listenerscan receive the information. However, in communication, it is not always easy to understand completely and exactly what is said and written, because the meaning of the word is complicated and sophisticated. The same word, used in these various situations, will have various meanings. The words indicating the color come up against with the same problems. Working as an isolated unity, the proverb is a combinatio of words taken from the general vocabulary of every language. We consider the words indicating the color in the proverbs and the proverbial expressions as the object of our study because the color is everywhere in our life : the color of the plants and animals, the color of the sky and the earth, the color of food, but also because the proverbs constitute a source of rich vocabulary for those who learn the language. The proverbs refers to diverse semantic fields and they reflect nicely the cultural difficulties related to learning of the French language in Iraq. Besides this, we would try to prove through transformations and manipulations that these proverbs can be frozen. An elaborate study of these semantic and syntactical features seemed to us absolutely essential to report the existence of the congealing in the proverbs, a very important and very complex linguistic phenomenon at the same time. Besides that, the critical comparison between these two languages : French and Arabic in this particular case, asserts that the phenomenon of the congealing is just a universal linguistic fact, and reveals that each language has its own mechanisms of congealing. We can note that, from the semantic point of view, the meaning of the proverbs is not calculated according to the rules of the compositionality ; in other words, the global meaning of the proverbs is not the addition of the meaning of the elements which compose them.