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No description available.

Asymmetric catalysis is vitally important for modern organic chemistry. However, many chiral catalysts are readily available only in a single absolute configuration. This often prevents practical access to both enantiomers of a product. To address this shortcoming, we propose a novel type of accessible ligands based on the structure of trans-5,6-disubstituted-5,6-dihydro-1,10-phenanthroline. Conformers of this molecule have opposite twist in the bipyridine fragment (opposite helicity or axial chirality). Thus, a relative stabilization of one or the other conformer of the same chiral precursor could potentially give access to two ligands with opposite axial chirality and hence to two catalysts with opposite enantioselectivity. We proposed structural modifications of substituents attached to 5,6-dihydro-1,10- phenanthroline as a convenient and reliable approach for stabilization of one or another conformer. To validate this strategy, multiple oxygen- and sulfur-substituted ligands were synthesized and fully characterized. In particular, their conformational behavior was studied by 1H NMR. Some ligands and their metal complexes were designed and proved to be conformationally (axially) constrained. Chiral resolution of these ligands through separation of their diastereomeric derivatives was accomplished, resulting in material of high optical purity. The absolute configuration of chiral elements (centers and axis) were established by 1H NMR, CD and X-ray analysis. Metal complexes with a range of novel chiral 5,6-dihydro-1,10-phenanthrolines were assessed as chiral catalysts for the asymmetric alkylation of aldehydes, Henry reaction and allylic substitution. Moderate to high activities were achieved in all catalytic transformations while low to moderate degree of enantioselectivity was observed. The results of asymmetric catalysis confirmed the crucial role of the twist in the ligand’s bipyridine moiety (of its sign and magnitude) in the induction of stereoselectivity. Exploring an undesired aromatization of products in cleavage of 5,6-epoxy-5,6- dihydro-1,10-phenanthroline with various thiols in presence of base, we developed a new simple procedure and synthesized a broad library of novel valuable ligands: 5-aryl(alkyl)sulfanyl-1,10-phenanthrolines and bis(1,10-phenanthrolines). Other functional groups attached to the thiol moiety allow using these products as building blocks for versatile ligands and in functionalization of surfaces. Besides, the new sulfur- substituted derivatives were found to be potent modulators of fungal glycosidases.

Amplified fragment length polymorphism (AFLP) markers allow a rapid assessment of the level of genetic variation that would be difficult to evaluate using a limited number of morphological markers. AFLP was used to assess the level of genetic variation among 16 different Phalaenopsis species and hybrids. Ten AFLP primer combinations were used for genetic analysis of these Phalaenopsis and 95% of polymorphism in 16 Phalaenopsis species and hybrids was detected. The genetic similarity among Phalaenopsis species and hybrids ranged from 0.298 to 0.774 based on Dice coefficient. The dendrogram derived by UPGMA analysis clustered into two main groups. A significant linear relationship (r² = 0.524, P < 0.0001) was observed between known pedigrees and AFLP-derived genetic similarity for 136 pairwise comparisons of Phalaenopsis species and hybrids. The results indicate that there is an abundance of genetic diversity among within Phalaenopsis and that AFLP can be used to distinguish morphologically similar genotypes. In a second study, the effect of gametophytic selection on genetic diversity in Phalaenopsis was examined by AFLP analysis. Sixteen F1 seedlings resulting from cross-pollination that occurred within high (30 ºC) and low (14 ºC) temperature incubators between two hybrid Phalaenopsis [P. (Taisoco Windian à Sogo Yukidian) by P. hybrid unknown], were subjected to genetic analysis by AFLP. A total of 651 fragments ranging in size from 100 to 350 bp were detected using six primer combinations, of which 387 (59.4%) were polymorphic. Seedlings derived from different temperature treatments exhibited 25.5% to 35.9% polymorphism. The genetic similarity among 16 F1 seedlings ranged from 0.825 to 0.946 based on the Dice coefficient. A dendrogram based on 387 polymorphic markers was derived by UPGMA analysis resulting in three major groups and one subgroup. The dendrogram analysis showed clear clustering in Phalaenopsis hybrids pollinated under different temperature treatments, suggesting that several loci may have been selected during the divergent temperature stress treatments during pollination and early pollen tube growth. / Master of Science

Rédigés de manière non linéaire, "Monsieur Teste" (1946) de Paul Valéry et "Palomar" (1983) d’Italo Calvino posent les limites de l’intellection pure et les possibilités du texte littéraire à rendre compte d’une conscience, celle des sujets – Teste et Palomar – , comme les témoins réfléchis des phénomènes de l’univers. Bien qu’issus d’époques et de mouvements littéraires différents (poésie moderne française de l’entre-deux guerre chez Valéry, le néoréalisme italien chez Calvino) les deux auteurs parviennent néanmoins à une écriture comparable, qui valorise l’éclatement formel des catégories romanesques conventionnelles (intrigue, espace, temps, personnage) vers un nouveau réalisme, plus libre et moins contraignant. Que ce soit par le récit composites "Monsieur Teste" où Valéry met en scène Teste, un homme taciturne et solitaire vivant de l’intérieur, ou encore "Palomar" dont le protagoniste décide, un beau jour, d’arpenter du regard la moindre parcelle de l’univers, un élément demeure constant : le fragment, comme manière d’appréhender et de comprendre le monde et, par ricochet, de se saisir soir-même. L’analyse des incidences littéraires du fragment nous permettra d’interroger et de mettre en lumière, en les comparant, l’écriture fragmentaire de "Monsieur Teste" et "Palomar" comme la création d’une structure textuelle, mais aussi comme une forme donnant vie à un contenu : la pensée prenant conscience de ses actes. / Written in non-linear fashion, Paul Valery’s "Monsieur Teste" (1946) and Italo Calvino’s "Palomar" (1983) establish limits for pure intellection and modern literatures possibility to account for subjective consciousness – that is, for Teste and Palomar – as thinking witness to phenomena of the universe. Althought stemming from different literary movement (for Valery, modern poetry of the inter-war period and, for Calvino, Italian Neorealism), both writers produce a similar form of writing that valorises the formal explosion of conventional categories (plot, spacetime, character) and points toward a new realism, freer and less restrictive. Whether it is in the composite narrative of "Monsieur Teste" representing Teste, a taciturn and solitary man with an inner life, or that of "Palomar" who suddenly decides to visually inventory the smallest parcels of the universe, one element remains constant : the fragment as a way of seizing and understanding the world and, indirectly, one self. Analyzing the fragment’s literary effects will allow us to reflect on and demonstrate by way of comparison, how the fragmentary writes of "Monsieur Teste" and "Palomar" create a textual structure as well of a form giving life to a content : thought becoming aware of its actions.

Ce travail a porté sur une nouvelle protéine impliquée dans l’apoptose, la mitogaligine, et plus particulièrement sur le fragment interne [31-53] responsable de son adressage à la mitochondrie. L’objectif général du projet est de comprendre au niveau atomique son mécanisme d’action sur les membranes mitochondriales. Le fragment d’adressage est à lui seul cytotoxique. C’est pourquoi j’ai concentré l’essentiel de mon travail de thèse sur son étude. Nous avons défini sa toxicité sur des cellules humaines et montré qu’il perturbait l’intégrité membranaire, excluant certaines protéines de la mitochondrie. Ce phénomène concorde avec le relargage de cytochrome c, à l’origine du déclenchement de l’apoptose par la voie mitochondriale. Pour mieux comprendre le mode d’action du fragment d’adressage et le rôle joué par la cardiolipine, lipide caractéristique des membranes mitochondriales, j’ai étudié par différentes techniques biophysiques complémentaires l’effet du milieu membranaire sur la structuration du peptide et l’effet du peptide sur la membrane. Le peptide a une très forte affinité (13nM) pour des membranes contenant de la cardiolipine. Il se place à plat sur la membrane, s’enfouissant dans l’interface, sans induire d’organisation particulière des lipides. De plus, nous avons mis en évidence que le peptide était capable d’induire une courbure positive de la membrane, ce qui va interférer avec de nombreux processus vitaux pour la cellule. Enfin, pour réaliser les études structurales et fonctionnelles de la protéine entière, j’ai participé aux premières étapes de production de mitogaligine, qui s’est avéré très délicate aussi bien par voie d’expression que par synthèse chimique. / This work is about a new protein of apoptosis, mitogaligin, and more particularly about the internal fragment [31-53] responsible for its mitochondrial targeting. General aim of the project is to understand at the atomic scale its mechanism of action on mitochondrial membranes. The addressing fragment is cytotoxic by itself. That is the reason why I focused the main part of my work on this peptide. We defined its toxicity on human cells and showed that it was capable of disrupting the membrane integrity, excluding some proteins from mitochondrion. This phenomenon agrees with the release of cytochrom c, which induces apoptosis by the mitochondrial pathway. In order to better understand the mode of action of the addressing fragment and the role played by Cardiolipin, a specific lipid of mitochondrial membranes, I studied by various and complementary biophysics techniques the effect of membrane environments on the peptide structuration and the effect of the peptide on the membrane. The peptide has a very high affinity (13nM) for cardiolipin-containing membranes. It takes place parallel to the membrane, standing at the interface, without leading to a particular lipids organization. Furthermore, we highlighted that the peptide was capable of inducing a positive curvature of the membrane, what is going to interfere with numerous vital processes for the cell. Finally, to realize the structural and functional studies of the whole protein, I was involved in the first stages of mitogaligin’s production, which has proved to be very tricky either by recombinant pathway or by chemical synthesis.

M.Sc. (Geology) / Please refer to full text to view abstract

L’étude diachronique des écrits en français de Cioran montre que le dynamisme de cette œuvre a pour source la manière d’écrire. L’univers idéel est statique. La manière de dire est en mouvement. La volonté de s’imposer sur la scène culturelle française pousse « le métèque » à mettre fin à son lyrisme. La frivolité qui consiste à jouer avec les idées en est la conséquence. Elle est à l’antipode de l’écriture philosophique dont la principale raison d’être est l’appréhension de l’essence des choses. Après l’échec des Syllogismes, Cioran s’est rendu compte qu’il a mal misé sur la frivolité des Français. A partir de La Tentation d’exister, il cherche à créer un texte relativement suivi. Un sceptique ne peut endurer cette corvée qu’en recourant à la fiction. La sécheresse des concepts abstraits est adoucie grâce à un langage métaphorique. La narration rompt avec les principaux procédés de l’écriture philosophique comme l’analyse et l’argumentation. Le texte évolue par contiguïté sémantique. Le conflit entre vérité et littérature devient moins intense. Le vieux Cioran, en proie au compte-gouttes de la vieillesse, souffre de ne plus pouvoir se manifester. Recourir à ses expériences quotidiennes ou à des passages lus est une source de matière verbale. Les scènes de la vie quotidienne rafraîchissent la conscience desséchée par la recherche exclusive de l’idée. La citation participe du même travail de concrétisation. La vie quotidienne a une valeur cognitive supérieure à celle du raisonnement philosophique. De même, les écrits des maîtres spirituels, des mystiques et des poètes sont plus pénétrants que les ouvrages philosophiques. Littérature et vérité se sont réconciliées. / The diachronic study of the writings in French of Cioran shows that the dynamism of this work has for manner source to write. The ideal universe is statistical. The manner to say is in movement to meet different challenges. The willingness to impose itself on the French cultural scene pushes the "Wog" to put an end to his lyricism. The frivolity of playing with ideas to create unusual forms is the consequence. It is the antithesis of the philosophical writing whose primary purpose to be the understanding of the essence of things. After the failure of Syllogismes, Cioran realized that he bet badly on the frivolity of the French people. From The Temptation to exist, it seeks to create a relatively tracking text. A skeptic cannot endure this chore than through fiction. The drought of abstract concepts is eased thanks to a metaphorical language. The narrative breaks with the main processes of philosophical writing as deduction, induction, analysis, synthesis and arguing. The text evolves by semantic contiguity. The conflict between truth and literature becomes less intense. The old Cioran, in prey to the dropper of the old age, suffer of more power to appear. To resort to its daily experiences or read passages is a source of verbal matter. The scenes of daily life refresh the dry conscience by exclusive research idea. The quote participates the same search for concrete. The daily life has a cognitive value than the philosophical reasoning. Similarly, the writings of spiritual teachers, mystics, poets and writers are more penetrating than philosophical work. Literature and truth are reconciled.

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La lutte contre les effets des Engins Explosifs Improvisés (EEI) constitue un enjeu majeur pour la sécurité intérieure et pour la protection des Forces Armées déployées à l’extérieur du territoire national. Parmi différents matériaux poreux, il a été démontré expérimentalement depuis les années 70 que les mousses aqueuses présentent une capacité à atténuer les ondes de choc. Différents mécanismes d’atténuation ont déjà été identifiés mais leur quantification reste encore peu expliquée. L’objectif de cette étude est de décrire les mécanismes physiques d’interaction d’une onde de choc sphérique entraînant de multiples fragments métalliques avec un volume de mousse aqueuse. En fonction de la distance entre la charge et la couche d’absorption, le choc est susceptible d’arriver avant les fragments, modifiant ainsi significativement la structure de la mousse et ses capacités d’atténuation et de ralentissement. Des essais de fragment unitaire ont été menés sur une configuration monodimensionnelle, essais dont les conclusions ont été validées sur une charge complète en champ libre à l’Institut franco-allemand de recherche de Saint Louis (ISL) dans le groupe "Protection contre les Explosifs". Des mesures de pression en tube à choc couplées à des visualisations d’interaction entre un choc et une couche de bulle ou une bulle unitaire ont permis de préciser la modification de la structure de l’onde de choc par la mousse. Ces essais ont été réalisés au LBMS (ENSTA Bretagne) et dans le groupe de recherche "Aérodynamique, mesures et simulations" (ISL) où il est possible de générer des profils de type souffle en tube à choc. / The fight against Improvised Explosive Device (IED) effects represents a permanent challenge for homeland security and armed forces protection deployed abroad. Aqueous foam was identified as a protective technology against blast effects in the 1970s. Several physical characteristics can account for this attenuation but their relative influences are still not completely determined and require further investigation. The objective of this study is to improve the knowledge of the physical phenomena governing the interaction between an aqueous foam layer and a shock/metallic fragments combination. Depending on the distance between the explosive charge and the absorption medium, the shock is likely to arrive before the fragments consequently modifying the foam structure. Experiments with a single fragment were undertaken in a one dimensional configuration. Obtained results were applied to predict the foam mitigation capability against a complete explosive charge detonated in free field at the French-German Research Institute of Saint-Louis (ISL) in the research group "Protection against Explosives". Pressure measurements in shock tube with visualization of shock/bubbles interaction provided precise information on the foam structure evolution during the impact process. These last experiments were conducted in LBMS (ENSTA Bretagne) and in the research group "Aerodynamic, Measurements and Simulations" (ISL), using a shock tube generating blast wave profiles.