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<p> Deuterium tracer studies, kinetic isotope effect measurements and product composition studies in both ammonia and ammonia-d3 have been used to elucidate the mechanism of the y-elimination reaction of 3-phenylpropyltrimethylammonium iodide with potassium amide in liquid ammonia at -55°. Deuterium tracer studies involving the products from the reaction of 3,3-dideutero-3-phenylpropyltrimethylammonium iodide have excluded the carbene and ylide mechanism. A deuterium exchange test involving the deuterated quaternary salt in ammonia demonstrated that a y-carbanion is formed during the reaction. In addition, a large y-hydrogen isotope effect (kH/kD > 22) and a large nitrogen isotope effect (k^14/K^15 = 1.022) were observed for the reaction. These results are consistent with either an Elcb mechanism in which the rates of ring closure and of return of the carbanion are of comparable magnitudes or a concerted mechanism accompanied by an irrelevant exchange reaction at the y-carbon. The latter has been eliminated on the basis of a deuterium exchange test involving the undeuterated quaternary salt in ammonia-d3 and the relative rates of y- and aelimination of the deuterated and undeuterated quaternary salts in both ammonia and ammonia-d3. </p> / Thesis / Doctor of Philosophy (PhD)

This paper is a study of the exchange of bismuth tetra-iodide and bismuth ions in an ion-precipitate system.

In preparation for the large backgrounds expected to be present in the Belle II detector from the SuperKEKB e+e- collider, the radiation hardness of several large (5 x 5 x 30 cm3) thallium doped cesium iodide (CsI(Tl)) scintillation crystals are studied. The crystal samples studied consist of 2 spare crystals from the Belle experiment using PIN diode readout and 7 spare crystals from the BaBar experiment using photomultiplier tube readout. The radiation hardness of the scintillation properties of the CsI(Tl) crystals was studied at accumulated 1 MeV photon doses of 2, 10 and 35 Gy. At each dose, the longitudinal uniformity of the crystals light yield, scintillation decay times, time resolution and energy resolution was measured. As the Belle II collaboration is considering an upgrade to pure CsI crystals if CsI(Tl) does not satisfy radiation hardness requirements, the scintillation properties of a pure CsI scintillation crystal were also measured and compared to the CsI(Tl) crystal measurements. In addition to experimental work, Monte Carlo simulations using GEANT4 were written to compare ideal pure CsI and CsI(Tl) crystals and to study the effects of radiation damage on the performance of the Belle II electromagnetic calorimeter. / Graduate

The work deals with the theory of preparing perovskite solar cells. How about basic structures and the specific types of training opportunities and reproducibility of results. In the third part describes the complete preparation of the article, which reached the highest efficiency and the procedure for subsequent repetition of the experiment

The use of brackish water and seawater desalination for augmenting potable water supplies has focused primarily on pre-treatment, process optimization, energy efficiency, and concentrate management. Much less has been documented regarding the impact of post-treatment requirements with respect to distribution system. The goals of this study were to review current literature on post-treatment of permeate water, use survey questionnaires to gather information on post-treatment water quality characteristics, gather operation information, review general capital and maintenance cost, and identify appropriate "lessons learned" with regards to post-treatment from water purveyors participating in the Project. A workshop was organized where experts from across the United States, Europe and the Caribbean active in brackish and seawater desalination, gathered to share technical knowledge regarding post-treatment stabilization, identify solutions for utilities experiencing problems with post-treatment, note lessons learned, and develop desalination water post-treatment guidelines. In addition, based on initial workshop discussions, the iodide content of reverse osmosis and nanofiltration permeate from two seawater desalination facilities was determined. The literature review identified that stabilization and disinfection are required desalination post-treatment processes, and typically are considerations when considering 1) blending, 2) re-mineralization, 3) disinfection, and 4) materials used for storage and transport of product water. Addition of chemicals can effectively achieve post-treatment goals although considerations relating to the quality of the chemical, dosage rates, and possible chemical reactions, such as possible formation of disinfection by-products, should be monitored and studied. The survey gathered information on brackish water and seawater desalination facilities with specific regards to their post-treatment operations. The information obtained was divided into seven sections 1) general desalination facility information, 2) plant characteristics with schematics, 3) post-treatment water quality, 4) permeate, blend, and point of entry quality, 5) post-treatment operation, 6) operation and maintenance costs, 7) and lessons learned. A major consideration obtained from the survey was that facilities should conduct post-treatment pilot studies in order to identify operational problems that may impact distributions systems prior to designing the plant. Effective design and regulation considerations will limit issues with permitting for the facility. The expert workshop identified fourteen priority issues pertaining to post-treatment. Priority issues were relating to post-treatment stabilization of permeate water, corrosion control, disinfection and the challenges relating to disinfection by-product (DBP) formation, water quality goals, blending, and the importance of informing the general public. For each priority issues guidelines/recommendations were developed for how facilities can effectively manage such issues if they arise. One of the key priorities identified in the workshop was related to blending of permeate and formation of DBPs. However, it was identified in the workshop that the impact of iodide on iodinated-DBP formation was unknown. Consequently, screening evaluations using a laboratory catalytic reduction method to determine iodide concentrations in the permeate of two of the workshop participants: Tampa Bay and Long Beach seawater desalination facilities. It was found that the permeate did contain iodide, although at levels near the detection limit of the analytical method (8 [micro]g/L).

Le transporteur de Na+/ acide monocarboxylique sensible à l’ibuprofène (SMCT1) est exprimé dans la membrane apicale de plusieurs épithélia. Son rôle physiologique dans la glande thyroïde reste cependant obscur mais on présume qu’il pourrait agir comme un transporteur apical d’iode nécessaire pour la synthèse des hormones thyroïdiennes. Récemment, on a montré que SMCT1 possède un courant de fuite anionique sensible à [Na+]e qui permettrait de transporter l’iode de façon électrogénique. Cependant, un efflux d’iode sensible à l’ibuprofène, mais indépendant de la [Na+]e a été aussi observé sur des cultures primaires des thyrocytes porcins, suggérant un autre mécanisme de transport d’iode par SMCT1. Ce travail vise à comprendre les caractéristiques de ce genre de transport en utilisant comme modèle d’expression les ovocytes de Xenopus laevis. Les résultats obtenus des essais de captation d’iode radioactif montrent que SMCT1 présente un transport d’iode sensible à l’ibuprofène de l’ordre de 30nmol/ovocyte/h. Si ce transport est non saturable en iode (0-100 mM), il nécessite du Na+ dans la solution externe. En effet, le remplacement du Na+ extracellulaire par le NMDG inhibe complètement le transport. En outre, on s’est intéressé à exclure la possibilité de différents artefacts. En ayant trouvé que la grande majorité de l’iode radioactif se trouve dans la partie soluble de l’ovocyte, on exclut une liaison non spécifique de l’iode à la membrane cellulaire. Cependant, une bonne proportion de l’iode transporté pourrait être liée à des protéines à l’intérieur de l`ovocyte. En effet, on observe une réduction du transport d’iode dans les ovocytes exprimant SMCT1 de 81,6 ± 2 % en présence de 2 % BSA dans la solution extracellulaire. Également, on écarte la possibilité que le transport d’iode soit le résultat de la surexpression de protéines de transport endogènes dont les canaux chlore. Le transport d’iode semble spécifique à l’expression de SMCT1 et de manière intéressante à l’expression d’un autre transporteur de monocarboxylates, MCT1. L’analyse de l’ensemble des essais, y compris le fait que l’amplitude du transport observé est 20 fois plus grande que celle du courant de fuite nous mène à proposer que SMCT1 puisse transporter l’iode de façon électroneutre. Cependant, le mécanisme par lequel ceci est accompli n’est pas évident à identifier. L’utilisation d’un autre modèle cellulaire serait surement utile pour répondre à cette question. / Ibuprofen sensitive, Sodium Monocarboxylate Transporter (SMCT1) is expressed in the apical membrane of diverse epithelia. Its physiological role in the thyroid remains however unknown, but it has been proposed that SMCT1 could act as an apical iodide transporter required for the main function of the gland: the thyroid hormone synthesis. We previously reported that SMCT1 exhibit a [Na+]e sensible anionic leak current that could account for the electrogenic transport of iodide. However, an iodine efflux sensitive to ibuprofen but independent of [Na+]e, was also observed in primary cultures of porcine thyrocytes, suggesting another mechanism of iodine transport mediated by SMCT1. This work aims to understand the characteristics of this type of transport using Xenopus laevis oocytes as an SMCT1 expression system. By realising 125I uptakes, we found that SMCT1 transports iodide in an ibuprofen sensitive manner (30nmol/oocyte/h). While nonsaturable uptake iodide kinetics were observed, SMCT1 iodide transport was Na+ dependent as shown by the transport reduction when the [Na+]e is replaced by NMDG. The possibility of artifacts, such as non specific binding and the overexpression of endogenous proteins, was analysed. By observing that the vast majority of the radioactive iodide is found in the soluble portion of the oocyte, we excluded non-specific binding of iodide to the cell membrane. However, it is believed that most of the iodide entering the cell is not free and must be bound to some intracellular proteins. Indeed, there is a significant reduction of SMCT1-mediated iodide transport when 2% BSA is present at the extracellular solution. Furthermore, the lack of iodide transport when overexpressing other proteins than SMCT1, precludes the possibility of an overexpression of endogenous transport proteins like chloride channels for example. In fact, the transport of iodide appears to be specific to the expression of SMCT1 and interestingly of another monocarboxylate transporter MCT1. The analysis of all trials, including the fact that the amplitude of the observed transport is 20 times larger than the leak current lead us to propose that SMCT1 can carry iodide in an electroneutral manner. However, the mechanism by which this is accomplished is not easy to identify and future experiments will be necessary to determine whether this transport is observed in other SMCT1 expression systems.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

The importance of gamma-ray spectroscopy – the science of determining the distribution of energy in a gamma field – can rarely be overstated. High performance scintillators for gamma-ray spectroscopy in Nuclear Nonproliferation applications and homeland security require excellent energy resolution to distinguish neighboring element and isotope lines while minimizing the time and exposure to do so. Semiconductor detectors operate by converting incident photons directly into electrical pulses, but often have problems of high costs due to constituent segregation and surface states as is the case for Cadmium Zinc Telluride. The ideal scintillator material for gamma spectrometer will therefore requires high light yield, excellent proportionality between light yield and gamma photon energy, and material uniformity. A scintillator should possess the following properties; it should convert the kinetic energy of the generated charged particles (typically K-shell electrons) into detectable visible light. This conversion should be linear-the light yield should be proportional to deposited energy over as wide a range as possible. For good light collection, the medium should be transparent to the wavelength of its own emission. The decay time of the induced luminescence should be short so that fast signal pulses can be generated. The medium should be of good optical quality and subject to manufacture in sizes large enough to be of interest as a practical detector. Its index of refraction should be near that of glass (~1.5) to permit efficient coupling of scintillation light to a photomultiplier tube or other photo-sensor. In the past decade, inorganic scintillator research has focused less on improving the characteristics of known scintillators, but rather on the search for new hosts capable of fast response and high energy resolution. Extensive searches have been made for hosts doped with lanthanide activators utilizing the allowed 5d-4f transition. These 5d-4f transitions are dipole-allowed and thus are about 106 times stronger than the more frequently observed 4f-4f transition in the trivalent rare earth ions. Ce3+, Nd3+ and Pr3+ have been investigated for fast response applications while Ce3+, Eu2+ and Yb2+ stand out as the most promising activators offering high light yield, and high energy resolution. Using a modified Bridgman growth technique we have grown crystals with a low energy resolution of 2.6% at 662 keV, which is lower than the previous 2.8% reported for SrI2:Eu2+. The modified technique (called so for its vertical crystal growth orientation) is necessary due to the anisotropic thermal expansion coefficient of Strontium Iodide. The problem plaguing the growth of the crystal is spontaneous cracking, which usually appear during cooling in the bulk. With the use of a zone separating shield, one can achieve more control of the temperature gradient between the two zones without compromising the actual temperature of the two zones. Additionally the use of codopants, in particular divalent magnesium improved the crystalline quality by acting as a gathering for iodine ions, which led to reduction of defect density.

Calculations have been carried out to investigate the stability and electronic structure of aluminum iodide clusters using first principles gradient-corrected density functional theory. Analysis of A113Ix-, A114Ix-, and A17I- clusters reveals that their stability is governed by the geometrically unperturbed A113-, A1142+, and A17+ units, respectively, that are demonstrated to constitute the compact cores of the clusters upon significant iodine content. The compact, icosahedral A113, icosahedral-like A1 14, and capped square bi-pyramid A17 superatom structures of the stable aluminum cores have an analogous electronic configuration to that of halogen, alkaline-earth, and alkaline atoms, respectively. Novel chemistry is demonstrated in superatoms, arising from two primary sources. Firstly, the calculations demonstrate the preference to break molecular I2 bonds in favor of iodine atoms individually adsorbing onto the aluminum sites of the central aluminum core surface. Secondly, the calculation show that observations of alternating stability trends dependent on the number of iodine ligands are connected to the formation and quenching of active sites. The significance of the induced active centers on aluminum iodide clusters upon association to alkenes is addressed, demonstrating a method towards predicting the location and extent of binding hydrocarbons. The novel chemistry of superatoms allows for a host of possible applications that integrate their unique properties in original ways and some key examples are described. Superatoms are the analogs to atoms and subsequently, just as the periodic table of elements lists atoms that can assemble into molecules and lattice structures, there exists the fathomable possibility to incorporate superatoms into extended structures such that they maintain their unique properties and result in a new class of materials. Initiation of such cluster-materials insinuates that cluster-mediated periodic table may be a proper extension to allow for a simple means for conveying fundamental information about clusters.