Yes / Objectives: Cocrystallization of sulfadimidine (SDM) with suitable coformers, such as 4-aminosalicylic acid (4-ASA), combined with changes in the crystal habit can favourably alter its physicochemical properties. The aim of this work was to engineer SDM:4-ASA cocrystals with different habits in order to investigate the effect on dissolution, and the derived powder properties of flow and compaction. Methods: Cocrystals were prepared in a 1:1 molar ratio by solvent evaporation using ethanol (habit I) or acetone (habit II), solvent evaporation followed by grinding (habit III) and spray-drying (habit IV). Key findings: Powder X-ray diffraction showed Bragg peak position was the same in all the solid products. The peak intensity varied, indicating different preferred crystal orientation confirmed by SEM micrographs: large prismatic crystals (habit I), large plate-like crystals (habit II), small cube-like crystals (habit III) and microspheres (habit IV). The habit III exhibited the fasted dissolution rate; however, it underwent a polymorphic transition during dissolution. Habits I and IV exhibited the highest Carr’s compressibility index, indicating poor flowability. However, habits II and III demonstrated improved flow. Spray drying resulted in cocrystals with improved compaction properties. Conclusions: Even for cocrystals with poor pharmaceutical characteristics, a habit can be engineered to alter the dissolution, flowability and compaction behavior. / Science Foundation Ireland. Grant Number: SFI/12/RC/2275

Yes / In order to investigate the effect of using different solid state forms and specific surface area (TBET) of active pharmaceutical ingredients on tabletability and dissolution performance, the mono- and dihydrated crystalline forms of chlorothiazide sodium and chlorothiazide potassium (CTZK) salts were compared to alternative anhydrous and amorphous forms, as well as to amorphous microparticles of chlorothiazide sodium and potassium which were produced by spray drying and had a large specific surface area. The tablet hardness and tensile strength, porosity, and specific surface area of single-component, convex tablets prepared at different compression pressures were characterized. Results confirmed the complexity of the compressibility mechanisms. In general it may be concluded that factors such as solid-state form (crystalline vs amorphous), type of hydration (presence of interstitial molecules of water, dehydrates), or specific surface area of the material have a direct impact on the tabletability of the powder. It was observed that, for powders of the same solid state form, those with a larger specific surface area compacted well, and better than powders of a lower surface area, even at relatively low compression pressures. Compacts prepared at lower compression pressures from high surface area porous microparticles presented the shortest times to dissolve, when compared with compacts made of equivalent materials, which had to be compressed at higher compression pressures in order to obtain satisfactory compacts. Therefore, materials composed of nanoparticulate microparticles (NPMPs) may be considered as suitable for direct compaction and possibly for inclusion in tablet formulations as bulking agents, APIs, carriers, or binders due to their good compactibility performance / Solid State Pharmaceutical Cluster (SSPC), supported by Science Foundation Ireland under Grant No. 07/SRC/B1158.

The purpose of this project was to distinguish between the karst and pseudokarst caves throughout Mississippi, create an inventory and survey of representative caves and karst features, identify the geology of the rocks hosting the caves, and produce a GIS-based digital karst map. The State of Mississippi is not known for its karst features, yet there are three distinct limestone units that contain dissolution caves: 1) Paleozoic (Mississippian) Tuscumbia Formation limestone; 2) Mesozoic carbonate units; and 3) Cenozoic limestone, Marianna Formation. There are a total of 44 caves known within the state based on past documentation, however the caves listed are not always differentiated between karst or pseudokarst features. This study located and mapped 20 caves, of which 18 were karst caves from eight counties and two were pseudokarst caves from two counties. Four of these caves were newly discovered karst caves, increasing the state total to 48; however two separate karst caves were connected, which makes the final state total 47 caves. Of the remaining 28 caves not surveyed, 11 were pseudokarst caves from eight counties and were not studied because the focus was on dissolutional karst caves. The remaining 17 missing karst caves either had been destroyed, access permission could not be obtained, or the caves could not be located. No active caving organizations exist in Mississippi to preserve cave location data or the caves themselves. Mining, deforestation, and other land use procedures have altered the landscape, resulting in concealment of some caves, and completely or partially destroying other caves.

No description available.

No description available.

Yes / Apigenin (4′,5,7-trihydroxyflavone, APG) has many potential therapeutic benefits; however, its poor aqueous solubility has limited its clinical applications. In this work, a large scale cocrystal screening has been conducted, aiming to discover potential APG cocrystals for enhancement of its solubility and dissolution rate. In order to reduce the number of the experimental screening tests, three computational prescreening tools, i.e., molecular complementarity (MC), hydrogen bond propensity (HBP), and hydrogen bond energy (HBE), were used to provide an initial selection of 47 coformer candidates, leading to the discovery of seven APG cocrystals. Among them, six APG cocrystal structures have been determined by successful growth of single crystals, i.e., apigenin-carbamazepine hydrate 1:1:1 cocrystal, apigenin-1,2-di(pyridin-4-yl)ethane hydrate 1:1:1 cocrystal, apigenin-valerolactam 1:2 cocrystal, apigenin-(dl) proline 1:2 cocrystal, apigenin-(d) proline/(l) proline 1:1 cocrystal. All of the APG cocrystals showed improved dissolution performances with the potential to be formulated into drug products.

Organic ligands, such as EDTA, accelerate the dissolution of silicate and oxide minerals. In natural systems oxyanions can compete with organic ligands for mineral surface sites thereby affecting ligand-promoted dissolution rates. Oxyanions can either enhance or inhibit dissolution depending upon pH. It has been suggested that the type of surface complex formed by the oxyanion is responsible for differences in ligand-promoted dissolution rates with mononuclear being dissolution enhancing and bi- or multinuclear being dissolution inhibiting. However, recent research has demonstrated that the type of surface complex formed by the oxyanion is not responsible for differences in ligand-promoted dissolution rates of oxide minerals. Accordingly, this manuscript examines the influence of selenite, molybdate, and phosphate on the EDTA-promoted dissolution of goethite and proposes a mechanism for the observed differences in dissolution rates over a pH range of 4 - 8. We propose that the surface complex formed by EDTA is the controlling factor for the observed dissolution rate, with mononuclear EDTA surface complexes accelerating goethite dissolution compared to bi- or multinuclear complexes. These experimental results suggest that EDTA forms multinuclear complexes with goethite surfaces at pH values greater than or equal to 6 and mononuclear complexes with goethite surfaces at pH values < 6. Dissolution results show that when the oxyanion and the EDTA are present in the system at concentrations nearly equaling the surface sites available for adsorption, the oxyanion reduces the adsorption of EDTA and inhibits dissolution over the pH range of 4 - 8. However, a different mechanism occurs at pH values greater than or equal to 6 when the oxyanion is present at 0.1 mM. EDTA adsorbs but the number of carboxylic groups that can sorb to the surface is reduced causing the formation of mononuclear complexes. This shift from multi- to mononuclear surface complexes enhances the EDTA-promoted dissolution of goethite in the presence of the oxyanions compared to EDTA-promoted dissolution in their absence. / Master of Science

La coffinite, USiO4, constitue l'une des phases pouvant être formées lors de l'altération d'un combustible usagé en conditions réductrices, après la dégradation des barrières de confinement. Une étude visant à déterminer les données thermodynamiques associées à la coffinite via une approche reposant sur la préparation de solutions solides d'uranothorites (Th1-xUxSiO4) a ainsi été développée au cours de ce travail. Dans un premier temps, la préparation des échantillons d'uranothorite a été entreprise avec succès en conditions hydrothermales. L'obtention systématique d'échantillons polyphasés pour x > 0,2 a toutefois permis de souligner les difficultés d'ordre cinétique liées à la synthèse en phase pure d'échantillons enrichis en uranium, dont le pôle pur constitué par la coffinite. La caractérisation des différents échantillons a néanmoins permis de confirmer la formation d'une solution solide idéale sur l'ensemble du domaine de composition et a conduit à la constitution d'une base de données spectroscopiques concernant ces systèmes chimiques. Par la suite, la purification des échantillons d'uranothorite a été entreprise par le biais de différents protocoles expérimentaux, basés sur des méthodes physiques (dispersion-centrifugation) ou chimique (dissolution préférentielle des phases secondaires). Cette dernière a ainsi montré l'élimination complète des impuretés (oxyde mixte Th1-yUyO2, et silice amorphe) à l'issue de cycles de lavage en milieu acide puis basique. Enfin, des expériences de dissolution ont été réalisées sur une série d'uranothorites (0 ≤ xexp. ≤ 0,5) et ont permis de déterminer l'influence de la composition, du pH et de la température sur la vitesse de dissolution normalisée des échantillons. Par ailleurs, les données thermodynamiques associées, telles que l'énergie d'activation, indiquent que la réaction de dissolution semble contrôlée par des phénomènes de surface. Après atteinte de l'équilibre, les constantes de solubilité analogues des uranothorites ont également été déterminées, permettant ainsi d'atteindre par extrapolation les données relatives à la coffinite et de conclure quant à l'inversion de la réaction de coffinitisation en fonction de la température. / USiO4 coffinite appears as one of the potential phases formed in the back-end of the alteration of spent fuel, in reducing storage conditions. A study aiming to assess the thermodynamic data associated with coffinite through an approach based on the preparation of Th1-xUxSiO4 uranothorite solid solutions was then developed during this work. First, the preparation of uranothorite samples was successfully undertaken in hydrothermal conditions. However, the polyphased samples systematically formed for x > 0,2 underlined the kinetic hindering linked with the preparation of uranium-enriched samples, including coffinite end-member. Nevertheless, the characterization of the various samples led to confirm the formation of an ideal solid solution and allowed the constitution of a spectroscopic database. The purification of the samples was then performed by the means of different protocoles based on physical (dispersion-centrifugation) or chemical (selective dissolution of secondary phases) methods. This latter led to a complete of the impurities (Th1-yUyO2 mixed oxide and amorphous silica) through successive washing steps in acid then basic media. Finally, dissolution experiments were undertaken on uranothorite samples (0 ≤ xexp. ≤ 0,5) and allowed pointing out the influence of composition, pH and temperature on the normalized dissolution rate of the compounds. Also, the associated thermodynamic data, such as activation energy, indicate that the reaction is controlled by surface reactions. Once the equilibrium is reached, the analogous solubility constants were determined for each composition studied, then allowing the extrapolation to coffinite value. It was then finally possible to conclude on the inversion of coffinitisation reaction with temperature.

This study addresses modern types of families in the East-Kazakhstan region and their role in the development of population. Using a sample of East-Kazakhstani women interviewed in 2008 in the "Family Transformation survey," this study focuses on continuously married women and women who have been previously married. The purpose of this thesis is analysis of factors influential on the intention to be divorced. Additionally, this thesis investigates issue: how a woman's family life-course (marital status and number of children born in the first marriage) influences the risk of a post-dissolution birth among divorced women. Also this study attempts to analyze how the experience of a marital dissolution affects a woman's cumulated fertility. The results show that women who underwent a marital dissolution have lower fertility than those who remained continuously married, and that repartnering enables this group of women to recapture the fertility lost with the dissolution of the first marriage. With a rise in divorce rates and existing differences of post-dissolution marital behaviors for those who have been previously married, it has become important to account for the type of dissolution (widowhood or divorce) of a union when analyzing partnership formation after the breakdown of a union. Additionally, this...

Cette thèse porte sur la production et l’étude de mousses polymères microporeuses, par dissolution de gaz. Plusieurs techniques expérimentales ont été améliorées ou adaptées pour la réalisation des mousses et la caractérisation des systèmes étudiés. De plus il est démontré que les paramètres du procédé, tels que la pression et la température, permettent la différenciation entre les différentes voies de moussage utilisées. Ceux-ci ont une influence significative sur les caractéristiques finales des mousses. / This dissertation focuses on the production and study of microcellular polymer foams by gas dissolution foaming. Due to the novelty of this research field several experimental techniques have been improved or adapted to produce the foams but also to provide valuable information from the systems understudy. It is demonstrated that processing parameters, such as pressure and temperature, allow differentiating between our foaming routes, and present a significant influence on the foaming process and final characteristics of foam.