Les phénomènes d’adsorption interviennent dans les processus géochimiques gouvernant ainsi le transport des contaminants. Par ailleurs, les variations de température sont susceptibles d’influencer significativement leur comportement vis-à-vis de la surface des minéraux. Aussi, l'influence de la température sur la sorption doit être étudiée afin de mieux appréhender le devenir des éléments dans l'environnement. Dans cette optique, l'interaction entre un ion modèle, l'uranyle et deux minéraux a été étudiée. Dans un premier temps, un composé méthodologique, la monazite, a été choisi afin de déterminer la démarche à suivre pour étudier l'influence de la température sur la sorption de l'uranyle dans trois milieux plus ou moins complexants. Puis, des tests préliminaires ont été réalisés pour étudier la sorption de l'uranyle sur un composé d'intérêt industriel, la magnétite, en appliquant la démarche mise en place. Le solide a d'abord été caractérisé d'un point de vue massif puis les caractéristiques acido-basiques de sa mise en suspension dans les trois électrolytes (NaClO4, NaNO3 et Na2SO4) ont été étudiées en fonction de la température. Les constantes d'équilibre associées aux réactions de déprotonation des sites de surface ont été déterminées entre 25°C et 95°C par modélisation de courbes de titrages potentiométriques. Les simulations ont été effectuées en limitant au maximum le nombre de degrés de liberté du système. Le modèle 1-pK a donc été préféré au modèle 2-pK en raison du nombre de paramètres ajustables plus limité dans ce modèle. Des contraintes expérimentales telles que le pH de point de charge nulle ou les enthalpies déterminées par mesure directe des chaleurs associées par microcalorimétrie de mélange ont été imposées pour déterminer les constantes d'équilibre acido-basiques. La sorption de l'uranyle en fonction du pH sur le même intervalle de température a été étudiée en alliant l'acquisition de données macroscopiques telles que les sauts de sorption et la spéciation en solution à une étude structurale menée par analyse par spectrofluorimétrie laser permettant l'identification des espèces sorbées. La simulation des sauts de sorption permettant d'accéder aux constantes associées aux réactions de sorption a été réalisée en imposant les caractéristiques acido-basiques préalablement déterminées. Des mesures directes, par microcalorimétrie de mélange, des chaleurs mises en jeu lors de la sorption de l'uranyle ont permis de tester la validité de la loi de Van't Hoff sur ce phénomène. La même démarche a été suivie pour étudier l'influence de la température sur la sorption de l'uranyle sur la magnétite en milieu NaClO4 et NaNO3. Cependant, l'étude structurale par spectrofluorimétrie laser n'a pu être réalisée en raison de la couloration noire de la magnétite. / The migration of radiotoxic elements in the geosphere is mainly regulated by chemical parameters which control the partitioning of the elements between mineral phases and aqueous solutions. Variation in temperature may affect the retention properties of a mineral surface and requires a careful investigation in order to understand the radionuclides behavior in the geosphere. In this way, the interaction mechanisms between uranium(VI) and two minerals (LaPO4 and Fe3O4) have been studied. In a first step, the monazite (LaPO4) has been chosen as methodological solid in order to clearly define all the different stages needed to completely characterize the influence of temperature on the sorption phenomena. To reach that goal, three media, more or less complexants towards aqueous uranyl and the mineral surface, have been considered. Physico-chemical as well as surface acid-base properties of the solid surface have been studied by considering three electrolytes (NaClO4, NaNO3 and Na2SO4) and temperatures ranged from 25°C to 95°C. The point of zero charge has been found to be identical for perchlorate and nitrate media (pHPZC=2.1) but it was found to be one pK unit higher for the sulfate medium indicating a sorption of the background electrolyte ions. The reaction heats associated to the hydration of the solid have been measured by using microcalorimetry and the nature of the reactive surface sites has been determined by carrying out Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS). On the basis of these experimental constraints, the titration curves obtained for the monazite suspensions were fitted by using the Constant Capacitance Model and the 1-pK model was preferred to characterize the surface charge evolution, due to the limited number of adjustable parameters. The surface protonation constants being determined, the behavior of U(VI) towards the monazite surface in the three electrolytes has been investigated. On the basis of both U(VI) speciation in solution and the results of a structural study carrying out by using TRLFS together with calorimetric measurements, the sorption edges have been modeled and the corresponding sorption constants determined. Since these values take into account a wide number of experimental results (both structural and thermodynamical ones) they appear to be accurate and could be extrapolated more confidently to other physico-chemical conditions. The experimental approach being validated with the methodological solid, preliminary tests have been carried out to study uranyl sorption onto a second substrate, the magnetite, more relevant than monazite in the field of radionuclides migration in the geosphere.

Cílem diplomové práce je vytvoření 2D numerického modelu pohybujícího se řezu s proměnnými okrajovými podmínkami skutečné geometrie plynulého odlévání a chlazení předlitku v prostředí MATLAB. Model se zabývá vysoce nelineárními termofyzikálními podmínkami oceli během tuhnutí a chlazení. V práci je simulovaná nejen nelinearita termofyzikálních podmínek, ale také nelinearita při fázové změně. Fázová změna je modelovaná pomocí metody entalpie, metody zdánlivé kapacity a metody teplotního zotavení. Všechny výsledky práce jsou porovnány z více hledisek, jako např. z hlediska přesnosti, rychlosti výpočtu, nebo vhodnosti časového diskretizačního kroku pro nelineární problémy, a paralelizace.

Nous développons dans ce travail de thèse un outil de simulation numérique pour les matériaux à changement de phase (MCP), en tenant compte du phénomène de convection naturelle dans la phase liquide, pour des configurations en deux et trois dimensions. Les équations de Navier-Stokes incompressible avec le modèle de Boussinesq pour la prise en compte des forces de flottabilité liées aux effets thermiques, couplées avec une formulation de l’équation d’énergie suivant la méthode d’enthalpie, sont résolues par une méthode d’éléments finis adaptatifs. Une approche mono-domaine, consistant à résoudre les mêmes systèmes d’équations dans les phases solide et liquide, est utilisée. La vitesse est ramenée à zéro dans la phase solide, en introduisant un terme de pénalisation dans l’équation de quantité de mouvement, suivant le modèle de Carman-Kozeny, consistant à freiner la vitesse à travers un milieu poreux. Une discrétisation spatiale des équations utilisant des éléments finis de Taylor-Hood, éléments finis P2 pour la vitesse et éléments finis P1 pour la pression, est appliquée, avec un schéma d’intégration en temps implicite d’ordre deux (GEAR). Le système d’équations non-linéaires est résolu par un algorithme de Newton. Les méthodes numériques sont implémentées avec le logiciel libre FreeFem++ (www.freefem.org), disponible pour tout système d’exploitation. Les programmes sont distribués sous forme de logiciel libre, sous la forme d’une forme de toolbox simple d’utilisation, permettant à l’utilisateur de rajouter d’autres configurations numériques pour des problèmes avecchangement de phase. Nous présentons dans ce manuscrit des cas de validation du code de calcul, en simulant des cas tests bien connus, présentés par ordre de difficulté croissant : convection naturelle de l’air, fusion d’un MCP, le cycle complet fusion-solidification, chauffage par le bas d’un MCP, et enfin, la solidification de l’eau. / In this thesis we develop a numerical simulation tool for computing two and three-dimensional liquid-solid phase-change systems involving natural convection. It consists of solving the incompressible Navier-Stokes equations with Boussinesq approximation for thermal effects combined with an enthalpy-porosity method for the phase-change modeling, using a finite elements method with mesh adaptivity. A single-domain approach is applied by solving the same set of equations over the whole domain. A Carman-Kozeny-type penalty term is added to the momentum equation to bring to zero the velocity in the solid phase through an artificial mushy region. Model equations are discretized using Galerkin triangular finite elements. Piecewise quadratic (P2) finite-elements are used for the velocity and piecewise linear (P1) for the pressure. The coupled system of equations is integrated in time using a second-order Gear scheme. Non-linearities are treated implicitly and the resulting discrete equations are solved using a Newton algorithm. The numerical method is implemented with the finite elements software FreeFem++ (www.freefem.org), available for all existing operating systems. The programs are written and distributed as an easy-to-use open-source toolbox, allowing the user to code new numerical algorithms for similar problems with phase-change. We present several validations, by simulating classical benchmark cases of increasing difficulty: natural convection of air, melting of a phase-change material, a melting-solidification cycle, a basal melting of a phase-change material, and finally, a water freezing case.

Two gas-phase ion-molecule reaction systems are presented here based on measurements done in a temperature variable 22-pole trapping machine. In the first case, the proton affinity of methane is determined based on a new technique for measuring the equilibrium constant of the HCO2+ + CH4 <=> CH5+ + CO2 reaction. The second case reports to the (Ar + N2 )+ reaction system, with reaction rate temperature dependencies measurements made both in the forward and reverse direction with different and complementary methods. The temperature variable 22-pole trapping machine allows one to determine equilibrium constants and reaction rate coefficients over a wide range of temperatures. The coupling of an effusive beam to the setup overcomes the problem of neutral gas wall condensation and extends the temperature range measurements beyond condensation point. The introduction (Chapter 1) gives a short overview about the rf technology and parallel experimental techniques developed in order to better characterize and understand the several mechanisms related to ion-molecule reactions. It also focuses some aspects of reaction rate temperature dependencies determination as well as thermodynamical equilibrium in laboratory environment. A short description of the setup and experimental methods are presented in Chapter 2. Based on equilibrium constant measurements, Chapter 3 is dedicated to the proton affinity of methane. This concept has applications on several fields such as atmospheric and combustion modelling, or testing empirical and ab initio theories for electronic structures. The (Ar − N2 )+ system presented in Chapter 4, is known for being a good case study for inferring the role of vibrational excitation in reaction dynamics and to the existence of non-adiabatic coupling. The experimental results here presented for the N2+ + Ar reaction demonstrate that it is possible to avoid parallel reactions with first vibrational excited state of nitrogen (N2 (ν = 1)). On the other hand, the reverse reaction experiments confirm the existence of a minimum of the reaction rate in the 30 to 300 K range, due to the existence of two reaction channels. The question of the high rate coefficient towards lower temperatures being related to the N2 rotational ground state population is raised. A summary and outlook are presented in Chapter 5, where some new possible paths of investigation are pointed out.

In dieser Arbeit wurde die Möglichkeit untersucht, Bortrihalogenide mit Wasserstoff unter milden Bedingungen (T < 100 °C, p(H2) < 50 bar) zu hydrieren. Um eine Triebkraft für die thermodynamisch ungünstige Reaktion zu erhalten, wurden Amine als Hilfsbasen zugesetzt, welche den bei der Reaktion entstehenden Halogenwasserstoff als Ammoniumsalz binden und damit das Reaktionsgleichgewicht in Richtung der Produkte verschieben. Es wurden dafür verschiedene Amin-Boran bzw. Amin-HCl Addukte synthetisiert und mittels IR, NMR und DSC charakterisiert. Bei den anschließenden Hydrierungsversuchen wurden verschiedene Katalysatoren auf ihre Eignung getestet und weiterentwickelt. Unterstützt wurden die experimentellen Arbeiten durch Berechnungen mit Gaussian 03. IR- und NMR-Spektren vieler Addukte wurden berechnet und freie Reaktionsenthalpien der Hydrierung in Abhängigkeit des verwendeten Amins und Borhalogenids bestimmt. Mögliche Übergangszustände wurden diskutiert und ihre Aktivierungsenergien ermittelt.:1. Einleitung und Problemstellung 2. Stand der Wissenschaft 2.1. Allgemeines 2.2. Die Amin-Boran-Addukte 2.3. Hydrierung mit Wasserstoff 2.3.1. Allgemeine Konzepte 2.3.2. Katalytische Hydrierung 2.3.3. Thermodynamische und kinetische Betrachtungen 2.4. Hydrierung mit Hydrosilanen 2.5. Quantenchemische Berechnungen 2.5.1. Grundlagen 2.5.2. Die Dichtefunktionaltheorie 2.5.3. Basissätze 2.5.4. Die Optimierungsverfahren 2.5.5. Übergangszustandsrechnungen 2.5.6. Weitere verwendete Methoden 2.6. 11B-NMR 3. Geräteteil 4. Durchgeführte Synthesen 4.1. Synthese von N-Ethyldiphenylamin 4.2. Synthese von N-Ethylbis(p-tolyl)amin 4.3. Synthese der BN-Addukte 4.4. Synthese der HCl-Addukte 4.5. Synthese von P-1 Nickel 5. Ergebnisse 5.1. Berechnungen mit Gaussian 5.1.1. Das Reaktionssystem auf Grundlage des Bortrichlorids 5.1.2. Die Hydrierung von Bortribromid und Bortriiodid mit Wasserstoff 5.1.3. Hydrierung mit Triethylsilan 5.1.4. Zusammenfassende Betrachtung der berechneten Ergebnisse 5.2. Die Addukte 5.2.1. Die "Amingrundtypen" 5.2.2. Die Addukte modifizierter Amine 5.2.3. Zusammenfassung 5.3. Hydrierung mit Triethylsilan 5.3.1. Allgemeines 5.3.2. Vergleich der Hydrierung der Bortrichlorid-Addukte von Triethylamin und N,N-Diethylanilin 5.3.3. Hydrierung bei verschiedenen Temperaturen 5.3.4. Zusammenfassung 5.4. Hydrierung mit Wasserstoff 5.4.1. Allgemeines 5.4.2. Hydrierversuche im Einkammerreaktor 5.4.3. Hydrierversuche im Zweikammerreaktor 5.4.4. Zusammenfassung 5.5. Weitere durchgeführte Experimente 5.5.1. Hydrierung von Disilanen 5.5.2. Zusatz von Chloridakzeptoren 6. Zusammenfassung und Ausblick 7. Anhang 7.1. Analytische Daten und Produktidentifizierung 7.1.1. NMR-Daten 7.1.2. IR-Daten 7.1.3. Einkristalldaten 7.2. Gaussian 03 Daten 7.2.1. Energien der Grundzustände 7.2.2. Energien der Übergangszustände 7.2.3. Berechnete IR-Spektren 7.2.4. Berechnete Reaktionsgrößen 7.2.5. Isotrope Abschirmungen 7.3. DSC-Daten 7.3.1. Boran-Amin-Addukte 7.3.2. HCl-Amin-Addukte 7.4. Die Hydrierungsansätze 8. Literaturverzeichnis 9. Formelverzeichnis

This diploma thesis is divided into three parts: theoretical, calculation and experimental measurement. The issue of humid air and air-conditioning in winter stadiums is elaborately analysed in the theoretical part. In the calculation part, the dessertation focuses on the optimization of current draft of hockey hall air conditioning system. The hall is now in operation during the season, which means from September to March. In the dissertation are discussed two variants of the draft. The first variant is draft upgrade to year-round operation with condensing dehumidification. The second option is solved as a combination of air handler unit system and absorption dehumidification. This variant is also designed for seasonal and year-round operation of the ice rink. At the end of the dissertation are all of them compared in terms of annual costs. The experimental measurement is carried out on dehumidification of air from areas with high water gains, in this case swimming pool hall model. This problematics is solved by changing the speed of ventilator and using Peltier generator.

Hydrocarbons are an abundant resource of carbon and hydrogen. For example, fossil can be used to produce useful organic compounds. However hydrocarbons seem to be inert. Thus, the activation of the C-H bond is a popular research area. Metals play the main role in most catalysts that convert hydrocarbons to starting materials in industry. The study of metals is important because the properties of the metal core greatly influences the reactivity of a catalyst.1 The study of the chemistry of metals in the gas phase provides valuable information about the properties of metals. This information can be expanded to the chemistry of metals in the condensed phase. Furthermore, it is often both more accurate and more manageable to study the profile of a reaction in the gas phase than in the condensed phase.2,3 There are many studies about metal cations in the gas phase due to ease of their production. However metals have low electronegativity, limiting the study of gas phase metal anions. Recently, a simple and efficient method to generate atomic metal anions was developed at the University of Ottawa in Dr. Mayer's research laboratory.4-6 Atomic metal anions of Fe-, Co-, Cu-, Ag-, Cs- and K- were generated in an electrospray ionization (ESI) source of a mass spectrometer (MS). In this thesis study generated metal anions were reacted with small hydrocarbons of pentane, 1-pentene, 2-pentene and 1-pentyne to investigate the role of different metal anions in the activation of the C-H bond. Also metal anions were reacted with small alcohols of 1-butanol, 2-butanol and 2-methyl-2-propanol to compare the results. Metal anions showed a variety of reactions with these hydrocarbons and alcohols. Fe- was the only metal anion to show the electron transfer reaction, indicating that alcohols are more electronegative than Fe- and less electronegative than other metal anions. Fe-, Co- and Ag- showed the complex formation reaction. All metal anions showed the deprotonation reaction. A deprotonation reaction follows the harpoon mechanism, the long range proton abstraction7, and depends on the gas phase acidity of fragments. The most informative reaction observed was the dehydrogenation reaction because a metal-containing fragment is observed as a product in the spectrum of this reaction. The observation of a metal-containing fragment in the spectrum is significant because it emphasizes the important role that metal anions play in this reaction. This suggests that a dehydrogenation reaction involves metal insertion into a C-H bond. Among the transition metal anions, it was observed that Fe- and Cu- are more reactive than Co- and Ag- with regards to the dehydrogenation reaction, probably because Fe- and Cu- have a greater hydrogen affinity than Co- and Ag- that facilitates the hydrogen abstraction reaction. Another reason could be that Fe- and Cu- have a greater gas phase acidity that leads to a more stable intermediate in the course of the reaction. The results of this thesis study revealed that Cs- and K- could not abstract H from these substrates, probably due to the absence of occupied d orbitals that would facilitate insertion into a C-H bond. Some metal anions not only can insert into a C-H bond of alcohols but also can insert into a C-O bond of alcohols to form metal hydroxide anions. Alcohols are more reactive than hydrocarbons with regards to reactions with metal anions because they contain a functional group. This thesis study shows that some atomic metal anions are able to activate the C-H bond and abstract two hydrogens to form a double bond in hydrocarbons. It is probable that the electronic configuration, gas phase acidity and hydrogen affinity of the metal anions governs their reactivity.

Hydrocarbons are an abundant resource of carbon and hydrogen. For example, fossil can be used to produce useful organic compounds. However hydrocarbons seem to be inert. Thus, the activation of the C-H bond is a popular research area. Metals play the main role in most catalysts that convert hydrocarbons to starting materials in industry. The study of metals is important because the properties of the metal core greatly influences the reactivity of a catalyst.1 The study of the chemistry of metals in the gas phase provides valuable information about the properties of metals. This information can be expanded to the chemistry of metals in the condensed phase. Furthermore, it is often both more accurate and more manageable to study the profile of a reaction in the gas phase than in the condensed phase.2,3 There are many studies about metal cations in the gas phase due to ease of their production. However metals have low electronegativity, limiting the study of gas phase metal anions. Recently, a simple and efficient method to generate atomic metal anions was developed at the University of Ottawa in Dr. Mayer's research laboratory.4-6 Atomic metal anions of Fe-, Co-, Cu-, Ag-, Cs- and K- were generated in an electrospray ionization (ESI) source of a mass spectrometer (MS). In this thesis study generated metal anions were reacted with small hydrocarbons of pentane, 1-pentene, 2-pentene and 1-pentyne to investigate the role of different metal anions in the activation of the C-H bond. Also metal anions were reacted with small alcohols of 1-butanol, 2-butanol and 2-methyl-2-propanol to compare the results. Metal anions showed a variety of reactions with these hydrocarbons and alcohols. Fe- was the only metal anion to show the electron transfer reaction, indicating that alcohols are more electronegative than Fe- and less electronegative than other metal anions. Fe-, Co- and Ag- showed the complex formation reaction. All metal anions showed the deprotonation reaction. A deprotonation reaction follows the harpoon mechanism, the long range proton abstraction7, and depends on the gas phase acidity of fragments. The most informative reaction observed was the dehydrogenation reaction because a metal-containing fragment is observed as a product in the spectrum of this reaction. The observation of a metal-containing fragment in the spectrum is significant because it emphasizes the important role that metal anions play in this reaction. This suggests that a dehydrogenation reaction involves metal insertion into a C-H bond. Among the transition metal anions, it was observed that Fe- and Cu- are more reactive than Co- and Ag- with regards to the dehydrogenation reaction, probably because Fe- and Cu- have a greater hydrogen affinity than Co- and Ag- that facilitates the hydrogen abstraction reaction. Another reason could be that Fe- and Cu- have a greater gas phase acidity that leads to a more stable intermediate in the course of the reaction. The results of this thesis study revealed that Cs- and K- could not abstract H from these substrates, probably due to the absence of occupied d orbitals that would facilitate insertion into a C-H bond. Some metal anions not only can insert into a C-H bond of alcohols but also can insert into a C-O bond of alcohols to form metal hydroxide anions. Alcohols are more reactive than hydrocarbons with regards to reactions with metal anions because they contain a functional group. This thesis study shows that some atomic metal anions are able to activate the C-H bond and abstract two hydrogens to form a double bond in hydrocarbons. It is probable that the electronic configuration, gas phase acidity and hydrogen affinity of the metal anions governs their reactivity.

La majorité des études structurales sur l’ADN avaient été réalisées par diffraction sur des fibres tandis que ses propriétés dynamiques thermiques avaient été étudiées en solution. Lorsque la double hélice d’ADN est chauffée elle présente des séparations locales des deux brins, dont la taille augmente avec la température jusqu’à la séparation complète des brins. Ce travail étudie différents aspects de ce phénomène. Les expériences présentées dans cette thèse ont été réalisées sur des films formés de fibres orientées d’ADN préparés par la méthode du ”filage humide“. La préparation et la caractérisation des échantillons en deux formes A et B de l’ADN ont constitué une partie importante de la recherche. Une méthode pour éliminer la contamination résiduelle de la forme B dans les échantillons de forme A a été mise au point. La bonne orientation des molécules d’ADN dans les échantillons nous a permis d’étudier les fluctuations dynamiques et la transition de dénaturation thermique de l’ADN par diffraction de neutrons, sensibles à la longueur de corrélation statique le long de la molécule en fonction de la température. La transition a été étudiée pour les formes A et B pour déterminer comment elle dépend de la conformation. De plus, après la première dénaturation thermique, les films d’ADN présentent un comportement typique d’un verre. Leur relaxation thermique a été étudiée par calorimétrie. La diffusion inélastique de neutrons et de rayons X (INS et IXS) avaient été utilisées antérieurement pour mesurer les phonons longitudinaux dans des fibres d’ADN, avec des désaccords entre les résultats. Des mesures INS récentes, complétées par des simulations, avaient été cruciales pour comprendre les différentes courbes de dispersion observées. Nous avons mené des expériences INS et IXS pour poursuivre cette analyse. Des tentatives pour observer les mouvements transversaux associés à la dénaturation thermique de l’ADN, jamais observés expérimentalement, ont également été faites. / The majority of structural studies on DNA have been carried out using fibre diffraction, while studies of its dynamics and thermal behaviour have been mainly performed in solution. When the DNA double helix is heated, it exhibits local separation of the two strands that grow in size with temperature and lead to their complete separation. This work has investigated various aspects of this phenomenon. The experiments reported in this thesis were carried out on films of oriented fibres of DNA prepared with the Wet Spinning Apparatus. Thus, sample preparation and characterisation are essential parts of the research. The structures of two forms of DNA, A and B, have been explored as a function of relative humidity at fixed ionic conditions. A method to eliminate traces of ever-present B-form contamination in A-form samples was established. The high orientation of the DNA molecules within the samples allowed us to investigate dynamical fluctuations and the melting transition of DNA using neutron scattering, which can provide the spatial information crucial to understand a phase transition, probing the static correlation length along the molecule as a function of temperature. The transition has been investigated for A and B-forms in order to understand its dependence on molecular configuration.Furthermore, after the first melting, denatured DNA films show typical glass behaviour. Their thermal relaxation has been explored using calorimetry.Neutron and X-ray inelastic scattering (INS and IXS) were used in the past to measure longitudinal phonons in fibre DNA, and the results shown disagreement. Recent INS measurements supported with phonon simulations have been crucial to understand the different dispersion curves reported to date. Experiments using INS and IXS have been carried out to continue with this investigation. Attempts to observe the transverse fluctuations associated to the thermal denaturing of DNA, never experimentally investigated before, have been made.

Diploma thesis focuses on effect of the bypass factor on design and geometry of the evaporator for the cooling unit of data centre. Effect of the bypass factor on individual design parameters is solved in detail. All dependendecies are captured by using graphs in which s placed a cement on that parameter. In part C, mathematical and physical solutions are demonstrated calculations and processes leading to the design of the exchanger. In the end, evaluation of the calculations is done and there is also showed possible improvements for the practise.