No description available.

Neutral diorganotin compounds of the 1,3-dithiole-2-thione-4,5-dithiolate ligand have been prepared. The syntheses of Me₂Sndmit, Et₂Sndmit, Bu₂Sndmit, (C₈H₁₇)₂Sndmit, (C₁₀H₂₁)₂Sndmit and (C₁₄H₂₉)₂Sndmit are described. For the purposes of indicating the formation of different structural phases, D.S.C. powder patterns are reported for initial and recrystallised samples of Me₂Sndmit, Et₂Sndmit and Bu₂Sndmit. Since Et₂Sndmitshowed different tin environments by solid phase state N.M.R. and clearly different powder patterns after recrystallisation, the compound was recrystallised from various solvents in an attempt to determine how many crystalline forms exist. To date, two forms have been identified: orthorhombic and monoclinic. The single crystal X-ray structure analyses of these are described. It has also been shown that upon heating a transition from the orthorhombic to the monoclinic form occurs at 140°C. The crystal strict of Me₂Sndmit has also been determined and is reported, along with Mossbauer parameters for Me₂Sndmit and Me₂Sndmio (dmio = 1,3-dithiole-2-one-4,5-dithiolate). Anionic organotin bis-dmit complexes of the form [RSn(dmit)₂][Q]⁺ have also been prepared, with a view to investigating their electrochemical properties. The syntheses of complexes with R chain length ranging from 4 to 18 carbons are described. The problem of formation of [Sn(dmit)₃][Q]₂ is also discussed. D.S.C. curves and cyclic voltammograms for [C₁₄H₂₉Sn(dmit)₂][C₁₄H₂₉NMe₃] and [NEt₄][(dmit)₂SnC₁₀H₂₀Sn(dmit)₂][NEt₄] are also described. Chiral macrocycles have potential uses as catalysts for asymmetric bond-forming reactions and as selective to metal ions. A chiral macrocyclic derivative of dmit was synthesised from methyl-4,6-<I>O</I>-benzylidene-2,3-bis-<I>O</I>-[(2-iodoethoxyethyl)-ethyl]-α-D-glucopyranoside. Since reaction of this with dmit proved to be unexpectedly problematic, attempted reactions of the sugar derivative with Na₂dmit<I> in situ</I>, isolated Na₂dmit, [Zn(dmit)₂][NEt₄]₂, [Ph₂Sn(dmit)I][NEt₄] and Cs₂dmit are described.

Aujourd'hui, les contenus et les applications Web sont devenus la principale interface pour effectuer toutes sortes de tâches de la vie quotidienne comme déclarer et payer les impôts, réserver des billets d'avion ou de train, planifier des vacances, effectuer des achats, gérer les comptes bancaires, etc. En conséquence, il devient de plus en plus important d'étudier leurs fondements, d'améliorer leurs capacités, de faciliter leur conception, de vérifier leur fonctionnement, de les optimiser automatiquement et les rendre plus souples et adaptables aux usages et aux différentes plateformes. Dans ce document, nous décrivons d'abord mes activités professionnelles, concernant les années 1998 à 2012. La première partie de ce document contient un résumé de mes activités de recherche, d'encadrement, d'enseignement et charges administrative et collective, ainsi qu'un résumé de mes principaux résultats scientifiques. Dans le reste du document, nous introduisons une logique de raisonnement sur les arbres finis, une procédure de décision correcte et complète pour vérifier la satisfaisabilité d'une formule de la logique ainsi que d'une mise en œuvre efficace en pratique. La logique est une variante du mu-calcul adaptée aux arbres finis et équipée avec des modalités arrières et des nominaux. Ensuite, nous considérons le problème de l'évolution des schémas XML. Dans le contexte en constante évolution du Web, les schémas XML changent continuellement afin de faire face à l'évolution naturelle des entités qu'ils décrivent. Les modifications de schémas peuvent avoir des conséquences importantes dans la mesure où les documents existants peuvent devenir invalides et la programmes les manipulant incorrectes. Nous proposons un cadre unificateur pour déterminer les effets de l'évolution des schémas XML à la fois sur la validité des documents et des requêtes contenues dans ces programmes. Dans la dernière partie du document, nous considérons une algèbre de type équipée de la récursivité, du produit cartésien, des fonctions, de l'intersection, de l'union, et du complément ainsi que des variables de type et une quantification universelle implicite sur ces variables. Nous considérons la relation de sous-typage récemment définie par Castagna et Xu sur des expressions de cette algèbre de type et montrons que le sous-typage peut être décidé avec une complexité EXPTIME et implémenté efficacement en pratique clôturant ainsi à une question ouverte dans la littérature.

Dans cette thèse nous commençons par décrire le groupe des automorphismes extérieurs du groupe des automorphismes polynomiaux du plan affine : il s'identifie au groupe des automorphismes du corps des complexes. Nous étendons ce résultat au groupe de Cremona ; les techniques utilisées sont différentes, le premier groupe ayant une structure de produit amalgamé ce qui n'est pas connu pour le second. Ensuite nous nous intéressons aux représentations de certains réseaux dans le groupe de Cremona ; nous obtenons un théorème de rigidité pour SL(3,Z) et des obstructions à ce que certains réseaux se plongent dans le groupe de Cremona. Enfin nous exhibons une famille de transformations birationnelles curieuses : bien qu'elles présentent toutes les caractéristiques des transformations réputées sans dynamique les expériences numériques révèlent des orbites chaotiques situées dans le complément de deux zones où les adhérences des orbites sont des tores ou des cercles.

Researchers in software engineering proposed design method for distributed applications to construct a set of communicating system components from a global behavior. The joint behaviors of these components must precisely satisfy the specified global behavior. The next concern is to transform the constructed models of these components into executable business processes by ensuring the exchange of asynchronous messages among the generated business processes. The introduction of Service-Oriented Architecture (SOA) has helped to achieve this goal. SOA provides high flexibility in composing loosely-integrated services that can be used among business domains to carry out business transactions; this composition is known as service orchestration. Moreover, SOA supports Model Driven Architecture (MDA) such that services modeled as UML Activity Diagrams (AD) can be transformed into a set of Business Execution Language (BPEL) processes. Many researchers discussed the transformation of UML AD and the Business Process Modeling Notation (BPMN) into BPEL. However, they did not discuss the practical limitations that some of these transformations impose. This thesis addresses the imitations of the transformation from UML AD to BPEL processes using the IBM Rational Software Architect (RSA). We showed here that the tool is unable to create the correct BPEL artifacts from UML AD components in certain cases, for instance when the behavior includes the alternative for receiving single or concurrent messages, a weak loop, or certain choice activities. Furthermore, we provided novel solutions to the transformations in these cases in order to facilitate the transformation from UML AD to BPEL.

This thesis introduces normal factor graphs under a new semantics, namely, the exterior function semantics. Initially, this work was motivated by two distinct lines of research. One line is ``holographic algorithms,'' a powerful approach introduced by Valiant for solving various counting problems in computer science; the other is ``normal graphs,'' an elegant framework proposed by Forney for representing codes defined on graphs. The nonrestrictive normality constraint enables the notion of holographic transformations for normal factor graphs. We establish a theorem, called the generalized Holant theorem, which relates a normal factor graph to its holographic transformation. We show that the generalized Holant theorem on one hand underlies the principle of holographic algorithms, and on the other reduces to a general duality theorem for normal factor graphs, a special case of which was first proved by Forney. As an application beyond Forney's duality, we show that the normal factor graphs duality facilitates the approximation of the partition function for the two-dimensional nearest-neighbor Potts model. In the course of our development, we formalize a new semantics for normal factor graphs, which highlights various linear algebraic properties that enables the use of normal factor graphs as a linear algebraic tool. Indeed, we demonstrate the ability of normal factor graphs to encode several concepts from linear algebra and present normal factor graphs as a generalization of ``trace diagrams.'' We illustrate, with examples, the workings of this framework and how several identities from linear algebra may be obtained using a simple graphical manipulation procedure called ``vertex merging/splitting.'' We also discuss translation association schemes with the aid of normal factor graphs, which we believe provides a simple approach to understanding the subject. Further, under the new semantics, normal factor graphs provide a probabilistic model that unifies several graphical models such as factor graphs, convolutional factor graphs, and cumulative distribution networks.

This thesis describes the results obtained from the phytochemical analysis of Matricaria chamomilla, and the microbial transformation of oxymatrine (85) and harmine (87), as summarized below. 1. Chemical investigation of the crude methanolic extract of Matricaria chamomilla resulted in the isolation of a new natural product, matriisobenzofuran (72), along with four known compounds: apigenin (73), apigenin-7-O-β-glucopyranoside (74), scopoletin (75), and fraxidin (76). The structures of compounds 72-76 were elucidated with the aid of extensive NMR and mass spectroscopic studies. All of the aforementioned compounds showed moderate to good inhibitory activities against glutathione S-transferase, an enzyme which has been implicated in the resistance of cancer cells to chemotherapeutic agents. These compounds were also evaluated for antioxidant activity and displayed moderate to good free radical scavenging activity. Additionally, compounds 72-76 were screened for anti-leishmanial activity. Compounds 75 and 76 were significantly active in this assay, while the remaining compounds were weakly active. In the antibacterial and antifungal assays, compounds 72-76 were not active. 2. The second part of this thesis deals with the biotransformation studies on oxymatrine (85) and harmine (87). Oxymatrine (85) was metabolized to the deoxy analogue, matrine (84) by Penicillum chrysogeneum (ATCC 9480), Cunninghamella bainieri (ATCC 9244), Cunninghamella blakesleena (ATCC 9245 and 8688A), Curvularia lunata (ATCC 12017), and Fusarium sp. In the time-based analysis of this transformation, the metabolism of oxymatrine (85) could be detected after 48 hours of incubation. Additionally, incubation of harmine (87) with Mucor plumbeus (ATCC 4740) resulted in the isolation of harmine-N-oxide (94). The biotransformed products (84 and 94) were identified using IR, UV, NMR, and mass spectroscopic techniques. Compound 94 was evaluated for its ability to inhibit the enzyme acetylcholinestrase, whose overexpression has been linked to Alzheimer’s disease, and was found to possess weaker activity than harmine (87).

The effect of large size ratios of solute to solvent on the critical properties and phase behaviour of binary mixtures of spherical particles is investigated using an "augmented van der Waals" equation of state. The equation used is essentially a van der Waals equation with an improved hard sphere repulsive term. Molecular dynamics and constant-pressure Monte Carlo simulations of binary mixtures of hard spheres with different diameter ratios and mole fractions are undertaken to check the adequacy of the hard sphere equation. Good agreement is found, even for systems with large differences in size. Furthermore, many of the hard sphere mixtures exhibited a transition from a fluid to a solid phase at high densities. Phase boundaries are calculated for model mixtures comprising spheres of different sizes between which there are long-ranged attractive forces. Particular attention is paid to the case in which the ratio of sizes is infinite. The systems show a wide variety of behaviour that includes liquid-liquid and gas-gas immiscibility, and the formation of negative azeotropes. Calculations investigating the effect of different attractive interactions between the small and large spheres show that as the magnitude of this interaction is increased, liquid-liquid immiscibility becomes the dominant feature of the phase diagram at moderate temperatures. The extent of liquid-liquid coexistence is greatest at large size differences. These model systems are shown to reproduce some of the behaviour of aqueous solutions of surfactants if it is assumed that the large spheres are models of the micelles and the small spheres models of the solvent molecules. The properties of binary lattice mixtures of bifunctional molecules whose ends are chosen to mimic surfactant and solvent molecules are also briefly investigated, to determine the effect of the asymmetric surfactant molecule on the phase separation. Closed-loops emerge in the phase diagrams as the surfactant character of one of the species is increased.

The requirement for lighter, safer and fuel efficient cars has created a major stir in the steel research society to develop advanced automotive steels. Since there is a trade off between strength and ductility, most of the conventional high strength steels do not address the strength-formability combination. With the realization of the TRIP phenomenon first in austenitic stainless steels, a new generation of advanced steels called TRIP steels were realised with an inexpensive and easier to process C-Mn-Si chemistry. TRIP or TRransformation Induced Plasticity is a phenomenon where the timely strain induced transformation of Retained Austenite (RA) to Martensite locally strengthens the steel at the point of plastic instability, causing failure by necking to be postponed and shifted elsewhere along the steel. This phenomenon repeated over and over again allows increased levels of strength and ductility, prior to fracture. / In current TRIP grades, the retained austenite particles present have to posses certain characteristics such as, optimum carbon concentration, optimum grain size and morphology etc. in order to account toward mechanical properties. Such limiting characteristics in turn minimize the processing window and make TRIP processing expensive and difficult to control. In this work, it is suggested that Tempered Martensite Assisted Steels (TMAS) obtained from TRIP steels via subcritical annealing of cold rolled TRIP steels may potentially replace TRIP steels. Relationship between the retained austenite volume fractions and mechanical properties was developed for TRIP steels. The effect of variation of retained austenite on tempered martensite volume fraction in TMAS, which in turn affect the mechanical properties was also investigated in depth. Results indicate that tempered martensite particles in TMAS do not have any limiting factors as in the case of RA in TRIP steels, in order to contribute toward enhancement of mechanical properties. Results also indicate that TMAS offers better strength levels compared to TRIP steels for same the level of formability. / Retained austenite volume fractions in TRIP steels were measured through XRD. Cold rolling of the samples was done in a laboratory scale rolling machine. The microstructures were analysed using conventional and color etching techniques. A new color etching technique for viewing all the four major phases in TRIP steel was developed in this work. The mechanical properties of both TRIP and TMAS were assessed by shear punch testing. And finally, the relationship between tempered martensite volume fraction and TMAS properties was developed and was compared to TRIP properties.

Ferromagnetic shape memory alloys FSMAs have diverse application, especially in the aerospace and bio-medical industries. They are a class of active and smart materials exhibiting strains under the influence of an applied magnetic field. These magnetic properties are mainly attributed to the martensitic structural phase trans- formation these material experience in response to temperature variation. Co-Ni-Al based alloys are one of the most promising ferromagnetic shape memory alloy FSMA that has been put recently under extensive study by researchers. They have shown extensive and promising features specifically those related to self-actuation. The effect of valence electron concentration and magnetic properties of Co-Ni-Al based ferromagnetic shape memory alloys on the martensitic transformations were analyzed utilizing Ab-initio first principle calculations. The variations of martensite start temperatures (Ms) and magnetic properties of a number of stoichiometric and mnon-stoichiometric Co-Ni-Al ferromagnetic shape memory alloys (FSMA’s) with B2 austenite structure were studied and analyzed as a function of composition and lattice site ordering and site preference. A major conclusion of this thesis suggests that the magnetic valence number (Zm) should be considered in conjunction to the e/a ratio if the composition profile of the Ms is to be determined. Both Monte-Carlo and Ab-initio simulations were implemented to obtain the magnetic Heisenberg’s exchange coupling parameters (J m) and model the magnetic transformations in stoichiometric Co2NiAl FSMAs. Two different cubic structures, ordered and disordered were compared to their tetragonal distortions martensitic phases and their Curie temperature (TC ) were obtained from the Monte-Carlo magnetic susceptibility temperature profile.