La croissance cristalline de KH2PO4(KDP)and K(H1-xDx)2PO4(DKDP)a été fortement étudiée depuis de nombreuses années. Les propriétés optiques nonlinéaires (conversion de fréquence: doublage pour le KDP et triplage pour le DKDP)et les études fondamentales sur les mécanismes de croissance sont à la base du développement important de la croissance de ces cristaux. Au début des années 90, un fort intérêt s'est porté sur le KDP et DKDP pour les dispositifs optiques à large ouverture pour les applications industrielles de fusion inertielle comme au NAtional Ignition Facility (NIF) aux USA ou pour le laser MégaJoule en France. La dimension de ces optiques (40*40 cm²) nécessite des cristaux géants crûs en solution. Une technique de croissance rapide a été développé par abaissement de température dans un réacteur de 1000L et par une filtration en continu afin d'éviter la nucléation spontanée. Cette méthode est très robuste et fiable pour la croissance rapide de cristaux géants de KDP mais néanmoins montre des limitations inhérentes à cette méthode. En effet, cela mène à des cristaux inhomogènes (défauts, inhomogénéités isotopiques)ce qui est rédhibitoire pour des solutions solides intermédiaires comme le DKDP : la composition en début de croissance peut varier significativement de celle en fin de croissance. Très récemment, des méthodes par circulation de solution en conditions stationnaires ont été développées pour palier à ce problèmeet sont considérées comme les plus pertinentes. C'est pourquoi nous avons développé un système par circulation en conditions stationnaires avec un traitement original de la solution. Dans un premier temps, le système a été testé sur un composé modèle KDP puis dans un deuxième sur le composé utilisé pour l'application DKDP. / Crystal Growth of KH2PO4(KDP)and K(H1-xDx)2PO4(DKDP)has been extensively covered over the years. For decades KDP and DKDP crystals have been grown either for their nonlinear optical properties (frequency conversion : doubling for KDP and tripling for DKDP) or for fundamental studies on crystal growth mechanisms. At the beginning of the 90's, a special interest arose for KDP for large aperture optical elements for laser fusion facilities such as the National Ignition Facility (NIF)in the USA or for the laser MegaJoule in France. The size of such optics(40*40 cm²)requires giant crystals to be grown in solution. A rapid growth technique has been developed based on the temperature lowering of a 1000L solution and its continuous filtration to avoid spurious nucleation. While this method is very robust and fully mature for the rapid growth of giant KDPs it nonetheless suffers from the limitations inherent to the Temperature Lowering Method(TLM).It does not provide stable growth conditions(temperature and supersaturation change).This can lead to inhomogeneous crystals (defects, isotopic inhomogeneity)and this is critical for intermediate of a solid solutions as the DKDP : the composition grown at the beginning can differ significantly from the one crystallizing later. Very early, transport methods growing crystals in stationary conditions, were considered to be "the most pertinent ones". That's why we have developed a growth system in stationary conditions with an original treatment of the solution. The grown compound selected was firstly KDP (model compound)then DKDP (KDP deuterated) for the desired application.

Ziel der Arbeit war eine Steigerung der Wasseraufnahme und Harndilution durch Supplementierung von Natriumchlorid (NaCl) oder pH-Wert-Senkung durch Zugabe von Ammoniumchlorid (NH4Cl) zur Reduktion des Harnsteinbildungspotenzials. Durch die NaCl-Zulage wurde die Harnmenge signifikant gesteigert und das spezifische Gewicht des Harns gesenkt. Eine NaCl-Gabe stellt somit einen möglichen ergänzenden therapeutischen Ansatz für eine vermehrte Ausscheidung von Kristallen dar. Eine Ansäuerung des Harns durch Zulage von NH4Cl ließ sich nicht erreichen.

This master’s thesis focuses on the minimisation of losses by calculation of optimum slip frequency of induction motor. The next point of this master‘s thesis is supersaturation. Supersaturation must be solved for the size of losses, because of the effect that is cause of the losses, when current increases with saturation. However current is not increase proportionally with increasing saturation, but increases several times more. This problem is included in the calculation of the slip frequency. Optimum of slip frequency is solve for modified gamma model of induction machine. In the main point of this thesis is outlined the process, how the optimum can be found. With same process were already were found the equations, but they were too extensit. In the end is solved the optimum of slip frequency be minimum of the flux density.

<p>Supersaturating drug delivery systems are an attractive solubility enabling formulation strategy for poorly soluble drugs due to their potential to significantly enhance solubility and hence, bioavailability. Compendial dissolution testing is commonly used a surrogate for assessing the bioavailability of enabling formulations. However, it increasingly fails to accurately predict <i>in vivo</i> performance due its closed-compartment characteristics and the lack of absorptive sink conditions. <i>In vivo</i>, drug is continually removed due to absorption across the gastrointestinal membrane, which impacts the luminal concentration profile, which in turn affects the dissolution kinetics of any undissolved material, as well as crystallization kinetics from supersaturated solutions. Thus, it is critical to develop an improved methodology that better mimics <i>in vivo</i> conditions. An enhanced approach integrates dissolution and absorption measurements. However, currently-used two-compartment absorptive apparatuses, employing a flat-sheet membrane are limited, in particular by the small membrane surface area that restricts the mass transfer, resulting in unrealistic experimental timeframes. This greatly impacts the suitability of such systems as a formulation development tool. The goal of this research is two-fold. First, to develop and test a high surface area, flow-through, absorptive dissolution testing apparatus, designed to provide <i>in vivo</i> relevant information about formulation performance in biologically relevant time frames. Second, to use this apparatus to obtain mechanistic insight into physical phenomenon occurring during formulation dissolution. Herein, the design and construction of a coupled dissolution-absorption apparatus using a hollow fiber membrane module to simulate the absorption process is described. The hollow fiber membrane offers a large membrane surface area, improving the mass transfer rates significantly. Following the development of a robust apparatus, its application as a formulation development tool was evaluated in subsequent studies. The dissolution-absorption studies were carried out for supersaturated solutions generated via anti-solvent addition, pH-shift and by dissolution of amorphous formulations. The research demonstrates the potential of the apparatus to capture subtle differences between formulations, providing insight into the role of physical processes such as supersaturation, crystallization kinetics and liquid-liquid phase separation on the absorption kinetics. The study also explores dissolution-absorption performance of amorphous solid dispersions (ASDs) and the influence of resultant solution phase behavior on the absorption profile. Residual crystalline content in ASDs is a great concern from a physical stability and dissolution performance perspective as it can promote secondary nucleation or seed crystal growth. Therefore, the risk of drug crystallization during dissolution of ASDs containing some residual crystals was assessed using absorptive dissolution measurements and compared to outcomes observed using closed-compartment dissolution testing. Mesoporous silica-based formulations are another type of amorphous formulations that are gaining increased interest due to higher physical stability and rapid release of the amorphous drug. However, their application may be limited by incomplete drug release resulting from the adsorption tendency of the drug onto the silica surface. Thus, the performance of mesoporous silica-based formulations was also evaluated in the absorptive dissolution testing apparatus to determine the impact of physiological conditions such as gastrointestinal pH and simultaneous membrane absorption on the adsorption kinetics during formulation dissolution. Overall, the aim of this research was to demonstrate the potential of the novel <i>in vitro</i> methodology and highlight the significance of a dynamic absorptive dissolution environment to enable better assessment of complex enabling formulations. <i>In vivo</i>, there are multiple physical processes occurring in the gastrointestinal lumen and the kinetics of these processes strongly depend on the absorption kinetics and <i>vice-a-versa</i>. Thus, using this novel tool, the interplay between solution phase behavior and the likely impacts on bioavailability of supersaturating drug delivery systems can be better elucidated. This approach and apparatus is anticipated to be of great utility to the pharmaceutical industry to make informed decisions with respect to formulation optimization.</p>

Research on salts species formed by evaporation of aqueous solution of Na2 in the early 1930s. The thermodynamic, crystallographic and many other physical and chemical properties of most of the species formed from this solution has been known for decades. However, there was no complete information or reliable data to confirm the existence of a unique double salt that is rich in sodium carbonate, up until five years ago when a research identified the double salt (~2Na ₂ CO ₃ • Na ₂ SO ₄) from the ternary system Na₂CO ₃Na₂SO ₄ H₂O. Crystallization of this double salt so called sodium sulfate dicarbonate (~2Na ₂ CO ₃ • Na ₂ SO ₄) is known to be a primary contributor to fouling heat transfer equipment in spent-liquor concentrators used in the pulp and paper industry. Therefore, understanding the conditions leading to formation of this double salt is crucial to the elimination or reduction of an industrial scaling problem. In this work, double salts were generated in a batch crystallizer at close to industrial process conditions. X-ray diffraction, calorimetry, and microscopic observation were used to investigate the stability of the salts to in-process aging, isolation and storage, and exposure to high temperature. The results show that care must be taken during sampling on evaporative crystallization. Two apparent crystal habits were detected in the formation of sodium sulfate dicarbonate; the favored habit may be determined by calcium ion impurities in the system. The results also verify that sodium sulfate dicarbonate exists as a unique phase in this system and that remains stable at process conditions of 115-200℃

This thesis is primarily focused on problems in extremal combinatorics, although we will also consider some questions of analytic and algorithmic nature. The d-dimensional hypercube is the graph with vertex set {0,1}^d where two vertices are adjacent if they differ in exactly one coordinate. In Chapter 2 we obtain an upper bound on the 'saturation number' of Q_m in Q_d. Specifically, we show that for m &ge; 2 fixed and d large there exists a subgraph G of Q_d of bounded average degree such that G does not contain a copy of Q_m but, for every G' such that G &subne; G' &sube; Q_d, the graph G' contains a copy of Q_m. This result answers a question of Johnson and Pinto and is best possible up to a factor of O(m). In Chapter 3, we show that there exists &epsilon; &gt; 0 such that for all k and for n sufficiently large there is a collection of at most 2^{(1-&epsilon;)k} subsets of [n] which does not contain a chain of length k+1 under inclusion and is maximal subject to this property. This disproves a conjecture of Gerbner, Keszegh, Lemons, Palmer, P&aacute;lv&ouml;lgyi and Patk&oacute;s. We also prove that there exists a constant c &isin; (0,1) such that the smallest such collection is of cardinality 2^{(1+o(1))^ck} for all k. In Chapter 4, we obtain an exact expression for the 'weak saturation number' of Q_m in Q_d. That is, we determine the minimum number of edges in a spanning subgraph G of Q_d such that the edges of E(Q_d)\E(G) can be added to G, one edge at a time, such that each new edge completes a copy of Q_m. This answers another question of Johnson and Pinto. We also obtain a more general result for the weak saturation of 'axis aligned' copies of a multidimensional grid in a larger grid. In the r-neighbour bootstrap process, one begins with a set A₀ of 'infected' vertices in a graph G and, at each step, a 'healthy' vertex becomes infected if it has at least r infected neighbours. If every vertex of G is eventually infected, then we say that A₀ percolates. In Chapter 5, we apply ideas from weak saturation to prove that, for fixed r &ge; 2, every percolating set in Q_d has cardinality at least (1+o(1))(d choose r-1)/r. This confirms a conjecture of Balogh and Bollob&aacute;s and is asymptotically best possible. In addition, we determine the minimum cardinality exactly in the case r=3 (the minimum cardinality in the case r=2 was already known). In Chapter 6, we provide a framework for proving lower bounds on the number of comparable pairs in a subset S of a partially ordered set (poset) of prescribed size. We apply this framework to obtain an explicit bound of this type for the poset &Vscr;(q,n) consisting of all subspaces of &Fopf;_qⁿordered by inclusion which is best possible when S is not too large. In Chapter 7, we apply the result from Chapter 6 along with the recently developed 'container method,' to obtain an upper bound on the number of antichains in &Vscr;(q,n) and a bound on the size of the largest antichain in a p-random subset of &Vscr;(q,n) which holds with high probability for p in a certain range. In Chapter 8, we construct a 'finitely forcible graphon' W for which there exists a sequence (&epsilon;_i)^&infin;_i=1 tending to zero such that, for all i &ge; 1, every weak &epsilon;_i-regular partition of W has at least exp(&epsilon;_i^-2/2^{5log&lowast;&epsilon;_i^-2}) parts. This result shows that the structure of a finitely forcible graphon can be much more complex than was anticipated in a paper of Lov&aacute;sz and Szegedy. For positive integers p,q with p/q &VerticalSeparator;&ge; 2, a circular (p,q)-colouring of a graph G is a mapping V(G) &rarr; &Zopf;_p such that any two adjacent vertices are mapped to elements of &Zopf;_p at distance at least q from one another. The reconfiguration problem for circular colourings asks, given two (p,q)-colourings f and g of G, is it possible to transform f into g by recolouring one vertex at a time so that every intermediate mapping is a p,q-colouring? In Chapter 9, we show that this question can be answered in polynomial time for 2 &le; p/q &LT; 4 and is PSPACE-complete for p/q &ge; 4.