Les liquides ioniques, associations de cations organiques et d'anions, sont des milieux structurés sur plusieurs nanomètres et présentent une ségrégation en domaines polaires et apolaires. Utilisés comme solvants de réactions catalytiques, ils peuvent de ce fait engendrer des phénomènes de solvatation spécifique. Ainsi des réactions d'échange d'ions dans certains systèmes catalytiques et des interactions de type p-cation avec les hydrocarbures insaturés ont été mises en évidence par RMN. Les conséquences de ces solvatations spécifiques sur des réactions d'hydrogénation ont été étudiées. Il ressort que plus l'interaction entre les liquides ioniques et les réactifs est grande, plus les réactions sont lentes. <br />Enfin la présence de microdomaines polaires et apolaires conduit à une solubilisation préférentielle des complexes organométalliques dans les poches apolaires ce qui permet d'utiliser ces milieux comme moules supramoléculaires et de contrôler la croissance cristalline des nanoparticules de ruthénium générées in situ en fonction de la longueur de la chaîne alkyl et de la température.

With its long cycle life and scalable design, the vanadium redox flow battery (VRB) is a promising technology for grid energy storage. However, high materials costs have impeded its commercialization. An essential but costly component of the VRB is the ion-exchange membrane. The ideal VRB membrane provides a highly conductive path for protons, prevents crossover of reactive species, and is tolerant of the acidic and oxidizing chemical environment of the cell. In order to study membrane performance and optimize cell design, mathematical models of the separator membrane have been developed. Where previous VRB membrane models considered minimal details of membrane transport, generally focusing on conductivity or self-discharge at zero current, the model presented here considers coupled interactions between each of the major species by way of rigorous material balances and concentrated solution theory. The model describes uptake and transport of sulfuric acid, water, and vanadium ions in Nafion membranes, focusing on operation at high current density. Governing equations for membrane transport are solved in finite difference form using the Newton-Raphson method. Model capabilities were explored, leading to predictions of Ohmic losses, vanadium crossover, and electro-osmotic drag. Experimental methods were presented for validating the model and for further improving estimates of uptake parameters and transport coefficients. / text

This work presents a new implementation of the QP algorithm, a computer method to diagonalize the extremely large matrices arising in multimode vibronic problems. Benchmark calculations are included, showing the accuracy of the program. The QP algorithm is extended to treat multiple electronic surfaces for competitive control and this is demonstrated with an Hamiltonian including three electronic states, a model of the benzene radical cation. Finally, the evolution of zeroth-order states in a simple two electronic states, two dimensional model with a conical intersection is explored, towards building a time-dependent view of overlapping resonances coherent control.

This work presents a new implementation of the QP algorithm, a computer method to diagonalize the extremely large matrices arising in multimode vibronic problems. Benchmark calculations are included, showing the accuracy of the program. The QP algorithm is extended to treat multiple electronic surfaces for competitive control and this is demonstrated with an Hamiltonian including three electronic states, a model of the benzene radical cation. Finally, the evolution of zeroth-order states in a simple two electronic states, two dimensional model with a conical intersection is explored, towards building a time-dependent view of overlapping resonances coherent control.

Requirements of high performing engine oil are today necessary since the development of new machinery with modern standardsis a cutting edge technology demanding highly optimized components. One way of increasing the lubricating properties of engineoil is through the addition of antioxidants. Antioxidants included in lubricants have a number of functions, one being buffering theinorganic acids sulphuric acid and nitric acid.A novel method expected to lower the hydrogen ion concentration in acidified engine oil was evaluated in this thesis. Thecapability of four different types of cation exchangers to serve as complements for buffering additives in heavy vehicle engineswas assessed. Two cation exchangers were weak and two were strong. The analysis techniques used to evaluate what effect thecation exchangers have on engine oil were standard test method ASTM D4739, for measurements of the total base number (TBN),and inductively coupled plasma – atomic emission spectroscopy (ICP-AES). With ASTM D4739 it was found that weak cationexchangers give positive results with respect to the ability to decrease the hydrogen ion concentration in acidified engine oil.However, after begin subjected to strong cation exchangers, ASTM D4739 indicated that the hydrogen ion concentration in theacidified engine oil remains the same or increases.With additional literature studies of a variety of cation exchangers currently on the market, further optimization of the cationexchanging material could likely be achieved. In addition, the preparation method used during the evaluation of the cationexchangers should be optimized to give more reliable results.

Kvantinės fizikos Hartre – Foko – Ruthano metodu atlikti teoriniai elektrinio krūvio tankio pasiskirstymo ant atomų skaičiavimai, nustatyta anglies nanovamzdelių, polimetininio dažo katijonų elektroninės sandaros priklausomybė nuo jų geometrinių parametrų ir nuo polimetininio dažo katijono padėties nanovamzdelyje. Nustatyta anglies nanovamzdelio kompozitų spektro kitimo priklausomybė. / Hartre – Fock – Ruthaan method of quantum mechanics, realized in GAMESS operating system, was applied in this research. Theoretical calculations of the distribution of electric charge density over atoms was carried out, the dependence of carbon nanotubes, polymethyne dye cations electron composition on geometrical parameters and the position of polymethyne dye cation (C11H19 N2+) in a tube . The analysis of energy levels of research subjects was carried out.

La présence croissante de diverses substances dans notre environnement, conséquencedes activités anthropiques de ces dernières décennies, a entraîné un besoingrandissant et urgent de nouveaux matériaux et dispositifs dans la quête de senseurschimiques efficaces et fiables. D'énormes progrès technologiques ont permis de mettreà disposition toute une gamme d'outils techniques pour leur développement, enprenant en compte les exigences à respecter en terme de sélectivité ou de rapidité deréponse, entre autres. Dans ce contexte, les méthodes de chimie quantique permettentune compréhension fondamentale des processus en jeu dans la détection des espèceschimiques, et par extension, l'élaboration de manière rationnelle de nouveauxmatériaux sensibles. Certaines molécules organiques pouvant être largementfonctionnalisées, elles constituent un point de départ idéal en raison des importantesmodulations possibles de leurs propriétés par des modifications structuralesappropriées.Cette étude vise à développer de manière rationnelle des chromoionophores pour lacomplexation de cations par une approche combinant méthodes de chimiecomputationnelles et caractérisation par spectroscopie optique. Deux pointsprincipaux ont été traités à l'aide de la Théorie de la Fonctionnelle de la Densité(DFT) et son extension dépendante du temps (TD-DFT): d'une part les relationsstructure moléculaire-propriétés optiques de chromophores, d'autre part le phénomènede complexation. En particulier, la détection de l'ion Zn2+, démontrée de manièrethéorique et expérimentale, est finalement réalisée après intégration du senseurmoléculaire dans un dispositif à fibre optique.

Les interactions entre facteurs génétiques et environnementaux, comme le stress, jouent un rôle important dans la physiopathologie de maladies psychiatriques telles que la dépression. Les transporteurs de cation organiques (OCTs) sont des transporteurs polyspécifiques considérés comme sensibles à la corticostérone. Au cours de ma thèse, je me suis intéressé au rôle du transporteur de cation organique 2 (OCT2) dans la réponse au stress et la vulnérabilité à la dépression. OCT2 est exprimé dans de nombreuses régions impliquées dans la réponse au stress et le long de l’axe hypothalamo-hypophyso-surrénalien (HPA). L’absence d’OCT2 entraîne une augmentation de la sécrétion de corticostérone (156%) en réponse à un stress aigu, sans altération de la sensibilité des surrénales à l’hormone adrénocorticotrope (ACTH). En conséquence, les souris OCT2-/- sont plus sensibles aux effets du stress chronique imprédictible léger et développent des anomalies comportementales transitoires de la mémoire spatiale et de l’interaction sociale dans la phase précoce du stress chronique. De plus, nous avons montré que l’état fonctionnel de la GSK3β, une voie de signalisation profondément modulée par le stress et la dépression, est altéré dans l’hippocampe des souris OCT2-/-. Des expériences pharmacologiques in vivo et des Western blot suggèrent qu’une augmentation du tonus sérotoninergique chez les souris OCT2-/- pourrait expliquer la dérégulation de la GSK3β lors du stress. Ce travail a permis d’identifier OCT2 comme un déterminant important de la réponse au stress, suggérant que chez l’homme des polymorphismes ou son inhibition pharmacologique lors de traitements thérapeutiques de longue durée pourraient altérer l’activité de l’axe HPA et rendre les individus vulnérables aux effets délétères du stress. / Interactions between genetic and environmental factors like exposure to stress play an important role in the pathogenesis of mood-related psychiatric disorders such as major depressive disorder. The polyspecific organic cation transporters (OCTs) were shown previously to be sensitive to the stress hormone corticosterone in vitro, suggesting these transporters might play a physiological role in the response to stress. During my PhD thesis I investigated the role of organic cation transporter 2 (OCT2) during stress and vulnerability to depression. OCT2 is expressed in several stress-related circuits in the brain and along the hypothalamic-pituitary-adrenocortical (HPA) axis. Genetic deletion of OCT2 in mice enhanced hormonal response to acute stress (156%) without altering adrenal sensitivity to adrenocorticotropic hormone (ACTH). As a consequence, OCT2-/- mice were potently more sensitive to the action of unpredictable chronic mild stress and developed a transient aggravation of depression-related behaviors involving spatial memory and social interaction. We showed that the functional state of the glycogen synthase kinase-3β (GSK3β) signaling pathway, highly responsive to acute stress, was altered in the hippocampus of OCT2-/- mice. In vivo pharmacology and Western blot experiments argue for increased serotonin tonus as a main mechanism for impaired GSK3β signaling in OCT2-/- mice brain during acute response to stress. Our findings identify OCT2 as an important determinant of the response to stress in the brain, suggesting that in man OCT2 mutations or blockade by certain therapeutic drugs could interfere with HPA axis function and enhance vulnerability to repeated adverse events leading to stress-related disorders.

Made available in DSpace on 2015-05-15T11:46:00Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3489954 bytes, checksum: 857373bbfa0d1a2ba6e371f0fab25e09 (MD5) Previous issue date: 2011-04-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work was dedicated to classify all the global phase portraits of the quadratic polynomial vector fields having a rational first integral of degree three. For this, techniques were used as blow-up, classification of singular points, invariant curves for a system of ordinary diferential equations and vector fields induced on the sphere. / Este trabalho foi dedicado a determinação global dos retratos de fase, no disco de Poincaré, dos campos vetoriais polinomiais quadráticos que possuem integral primeira racional de grau três. Para determinar o retrato de fase, utilizamos técnicas como blow-up, classi- ficação dos pontos singulares, curvas invariantes para um sistema de equações diferenciais ordinárias e a indução de campos vetoriais sobre a esfera.

This thesis is dedicated to the theoretical study of the methyl cation CH3+ electronic states and, globally, falls within the study of the interstellar clouds molecular synthesis and the chemistry of the hydrocarbons which are present in high-energy plasmas such as in the experimental nuclear fusion reactor ITER. Among the different possible formation reactions, we chose two reactions involved in these fields: the ionization of the methyl radical CH3 ground state and the reactive collisions between simple carbonated or hydrocarbonated (C, CH+ and CH2+) and hydrogen species (H3+, H2 and H, respectively).<p><p>As this cation is characterized by 8 electrons and 4 nuclei, this allowed us to perform high-level ab initio calculations using the CASSCF/MRCI method with the Dunning aug-cc-p(C)VXZ basis sets. These calculations were completed by a study of different methodological effects such as the core-valence electronic correlation, the complete basis set extrapolation and the basis set superposition error.<p><p>We calculated equilibrium geometries (precision within 10^-5 angtröm and 10^-2° and their energies for the methyl radical and cation, studied the potential energy surfaces involved by the Jahn-Teller effect targeting the methyl cation E' states and achieved frequencies calculations. From these values were derived ionization potentials (IP) from the methyl radical ground state towards the methyl cation lowest-lying states (precision within 10^-2 eV). Vibrational corrections and nuclear relaxation effects were taken into account.<p><p>The calculated IPs and frequencies should facilitate the analysis of methyl radical threshold photoelectron spectra leading to the methyl cation lowest-lying states, recorded at the synchrotron facility Soleil by the Dr. Alcaraz group from the Université Paris-Sud.<p><p>Through reaction paths calculations using a quadratic steepest-descent method, we have proposed new reactional pathways enabling the connections between the different dissociation channels correlated to the cation lowest-lying triplet states. The absence of potential barriers in the energy profiles allows us to propose these reactions as sources, in interstellar clouds, of hydrocarbonated molecules whose stability increases with growing size according to the series C -> CH+ -> CH2+ -> CH3+.<p><p>The groups of Pr. Urbain from UCL and Dr. Savin from Columbia University studied the collisions in copropagating beams of C and H3+ leading to the formation of these hydrocarbonated species. The proposed reactional mechanisms are in good agreement with the experimental observations, what permits a better understanding of the chemistry behind these collisional processes of astrochemical interest. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished