In spite of their high abundance and importance, aqueous systems are enigmatic on the microscopic scale. In order to obtain information about their geometrical and electronic structure, simple aqueous solutions have been studied experimentally by photo- and Auger electron spectroscopy using the novel liquid micro-jet technique in conjunction with synchrotron radiation. The thesis is thematically divided into three parts. In the first part we utilize the surface sensitivity of photoelectron spectroscopy to probe the distributions of solutes near the water surface. In agreement with recent theoretical predictions we find that large polarizable anions, such as I- and ClO4-, display enhanced surface propensities compared to smaller rigid ions. Surface effects arising from ion-ion interactions at higher electrolyte concentrations and as function of pH are investigated. Studies of linear mono-carboxylic acids and benzoic acid show that the neutral molecular forms of such weak acids are better stabilized at the water surface than their respective conjugate base forms. The second part examines what type of information core-electron spectra can yield about the chemical state and hydration structure of small organic molecules in water. We demonstrate that the method is sensitive to the protonation state of titratable functional groups and that core-level lineshapes are dependent on local water hydration configurations. Using a combination of photoelectron and X-ray absorption spectroscopy we also show that the electronic re-arrangement upon hydrolysis of aldehydes yields characteristic fingerprints in core-level spectra. In the last part of this thesis we study ultrafast charge delocalization dynamics in aqueous solutions using resonant and off-resonant Auger spectroscopy. Intermolecular Coulombic decay (ICD) is found to occur in a number of core-excited solutions where excess energy is transferred between the solvent and the solute. The rate of ultrafast electron delocalization between hydrogen bonded water molecules upon oxygen 1s resonant core-excitation is found to decrease upon solvation of inorganic ions. The presented work is illustrative of how core-level photoelectron spectroscopy can be valuable in the study of fundamental phenomena in aqueous solutions.

No description available.

Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2018-01-31T16:42:14Z No. of bitstreams: 0 / Made available in DSpace on 2018-01-31T16:42:14Z (GMT). No. of bitstreams: 0 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A deposição de rejeitos radioativos em repositórios geológicos profundos vem sendo estudada nos últimos anos em diversos países. Materiais à base de cimento são utilizados nesses repositórios como material estrutural, matriz de imobilização de rejeitos ou material de preenchimento. Compreender o desempenho desse material é essencial para garantir a segurança da instalação durante o seu tempo de vida útil (de milhares a centenas de milhares de anos, dependendo do tipo de rejeito). Este trabalho objetiva modelar o comportamento em longo prazo do cimento Portland e estudar a influência de diversos fatores na hidratação e na evolução desse material. A modelagem descritiva abordou a hidratação do cimento nas condições ambientais esperadas no repositório e os efeitos desses fatores em propriedades mecânicas, mineralógicas e morfológicas do cimento. Os fatores ambientais considerados relevantes neste trabalho foram: alta temperatura e pressão, penetração de água subterrânea contendo íons quimicamente agressivos ao cimento e a presença do campo de radiação proveniente dos rejeitos. Ensaios acelerados de degradação também foram realizados para corroborar com o modelo descrito. Observou-se uma sinergia entre diversos fatores na degradação do cimento, como a influência da temperatura e da radiação em reações deletérias ao material. O resultado da modelagem apontou três principais possíveis causas de falha nas barreiras artificiais: a) a formação de um caminho preferencial; b) a perda de resistência e coesão do material; e c) o aumento na corrosão das estruturas metálicas. A descrição do modelo apresentada é a base para a modelagem matemática e a análise de segurança dos repositórios estudados no Brasil. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP / CAPES:1231206

Dans cette étude, la nucléation, la croissance, la morphologie et la réactivité de nanoparticules Au, Cu et AuCu sont examinées sur support rutile TiO2 (110) stoechiométrique, réduit et hydraté. En premier lieu, la nucléation a été modélisée via l’adsorption et la diffusion d’atomes Au et Cu, à l’aide de calculs de type théorie de la fonctionnelle de la densité (DFT), et de diagrammes d’énergie libre en condition réaliste.Les résultats DFT+U ont montré le rôle promoteur des espèces hydroxyles en surface sur la nucléation, en accord avec les mesures expérimentales de microscopie STM. Ensuite, les propriétés thermodynamiques de croissance et de coalescence de clusters Au et Cu (de 1 à 38 atomes) ont été étudiées par une approche systématique qui a déterminé précisément la stabilité relative d’un grand nombre de structures, tout en soulignant la différence de compétition nucléation/croissance entre les deux métaux. Pour des tailles de particules comprises entre 38 et 201 atomes, et des morphologies variées, la stabilité absolue d’agrégats purs Au et Cu et de nanoalliages AuCu a été évaluée à l’aide de calculs d’énergie de surface. Cette approche a révélé l’existence de relations linéaires entre composition chimique et stabilité. Enfin, la réactivité de nanoparticules Au, Cu et AuCu a été examinée suivant deux aspects : le dépôt de clusters de 38 atomes sur support rutile stoechiométrique, et l’adsorption du monoxyde de carbone à l’interface entre le métal et le support.Cette adsorption est une étape clé pour la réaction d’oxydation du CO ; un procédé important en catalyse hétérogène. / In this study, the nucleation, growth, morphology and reactivity of Au, Cu and AuCu nanoparticles have been examined on rutile TiO2 (110) stoiciometric, reduced and hydrated supports. First, the nucleation has been modeled via the adsorption and diffusion of Au and Cu atoms, thanks to density functional theory (DFT) calculations, and free energy diagrams in realistic conditions. DFT+U results have shown the promotor role of surface hydroxyl species on the nucleation, in agreement with STM experimental measurements.Then, the growth and coalescence thermodynamic properties for Au and Cu clusters (from 1 to 38 atoms) have been investigated with a systematic approach which has determinated precisely the relative stability for a large number of structures, and has underlined the difference for the competition between nucleation and growth between the two metals. For particles in the range 38-201 atoms and varied morphologies, the absolute stability of Au and Cu aggregates and AuCu nanoalloys has been evaluated through surface energy calculations. This approach has revealed the existence of linear relations between the chemical composition and the stability.Finally, the reactivity of Au, Cu and AuCu nanoparticles has been examined following two aspects : the deposition of 38 atoms clustered on the stoichiometric rutile support, and the adsorption of carbon monoxide at the interface between the metal and the support. This adsorption is a key step for the CO oxidation reaction ; an important process in heterogeneous catalysis.

Background: Compare Goldmann applanation tonometer (GAT) prism and correcting applanation tonometry surface (CATS) prism to intracameral intraocular pressure (IOP), in vivo and in vitro. Methods: Pressure transducer intracameral IOP was measured on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically to 10, 20, and 40 mmHg. Simultaneously, IOP was measured using a Perkins tonometer with a standard GAT prism and a CATS prism at each of the intracameral pressures. Statistical comparison was made between true intracameral pressures and the two prism measurements. Differences between the two prism measurements were correlated to central corneal thickness (CCT) and corneal resistance factor (CRF). Human cadaver eyes were used to assess measurement repeatability. Results: The CATS tonometer prism measured closer to true intracameral IOP than the GAT prism by 1.7+/-2.7 mmHg across all pressures and corneal properties. The difference in CATS and GAT measurements was greater in thin CCT corneas (2.7+/-1.9 mmHg) and low resistance (CRF) corneas (2.8+/-2.1 mmHg). The difference in prisms was negligible at high CCT and CRF values. No difference was seen in measurement repeatability between the two prisms. Conclusion: A CATS prism in Goldmann tonometer armatures significantly improve the accuracy of IOP measurement compared to true intracameral pressure across a physiologic range of IOP values. The CATS prism is significantly more accurate compared to the GAT prism in thin and less rigid corneas. The in vivo intracameral study validates mathematical models and clinical findings in IOP measurement between the GAT and CATS prisms.

L’étude menée s’attache à évaluer le potentiel d’activation du laitier de haut fourneau dans un liant ternaire constitué de ciment alumineux, de sulfate de calcium et de laitier. Dans ce système ternaire, le constituant majoritaire est le sulfate de calcium. Le potentiel d’un tel système n’est pas encore connu mais cette étude vise à renseigner sur les principaux avantages et limites d’utilisation. D’un point de vue des propriétés d’usage de ce liant, la prise, le durcissement rapide et la montée des résistances sont assurés par le liant ettringitique. Ensuite, et uniquement si la dessiccation est évitée, le laitier de haut fourneau réagit et dans ce cas, l’apport du laitier dans de tels systèmes est double. Il contribue à l’augmentation des performances mécaniques à moyen et long terme et à limiter l’expansion sous eau. D’un point de vue de la compréhension des mécanismes d’hydratation, une démarche expérimentale originale est mise en place et dévoile le potentiel du laitier. Elle est basée sur la comparaison des performances obtenues avec différentes cures. Le potentiel d’hydratation du laitier est amplifié lorsque le système subit un séchage puis une réhydratation. Cependant, les techniques utilisées (diffraction des rayons X et calorimétrie différentielle à balayage) ne sont pas adaptées au suivi et à la quantification de laitier consommé. Ainsi, la compréhension de l’hydratation s’appuie sur des techniques dites indirectes. Une semi-quantification par diffraction des rayons X est réalisée pour le suivi et l’évaluation de la mayénite, le sulfate de calcium (anhydre ou dihydraté), la syngénite et l’ettringite, l’analyse thermogravimétrique permet de mesurer le degré d’hydratation du système, et la porosimétrie mercure informe sur les changements microstructuraux. La plus grosse difficulté dans ces travaux a porté sur le suivi et la quantification des phases amorphes (anhydres ou hydratées), telles que le laitier, les gels de C-S-H et d’AH3, et c’est pour cette raison qu’une approche par modélisation a été mise en place afin d’identifier le rôle de chaque constituant du système ternaire [Ciment Alumineux – Sulfate de Calcium – Laitier] et particulièrement du laitier lors de l’essai de réhydratation. L’approche par modélisation permet de mieux identifier les phénomènes chimiques et physiques ayant lieu lors de l’hydratation du liant. Elle est utilisée pour expliquer les observations macroscopiques (comme les performances mécaniques) et aide à déterminer les cinétique d’hydratation dans le milieu poreux. Le modèle utilisé n’est pas encore parfaitement au point mais il a permis d’identifier les différentes séquences d’hydratation (à savoir que le liant ettringitique réagit dans les premiers instants et qu’ensuite, l’hydratation de l’anhydrite entraine la formation de gypse et l’hydratation du laitier est effective à long terme) et de confirmer que la réaction du laitier est lente. / The potential of activation of a Ground Granulated Blast Furnace Slag has been evaluated into a ternary system comprising of a Calcium Sulfate as major component and a Calcium Aluminate Cement. This system is not well known and the main goal of this study is to determine its main advantages and limitations. From the usage properties point of view, fast setting and initial strengths are governed by the ettringitic binder. Then, and only if the dehydration is avoided, slag reacts. In this case, slag contributes to the increase of mechanical performances at medium and long terms and to limit the expansion under water. From an understanding point of view, the original experimental approach reveals the potential of the slag. It is based on a comparison of performances with different types of curing methods. The potential of hydration of the slag is amplified when the system is dehydrated during a few days and then rehydrated. However, slag contribution is complex to establish because analytical methods to follow-up slag consumption (such as X-ray Diffraction and Differential Scanning Calorimetry analysis) are not well adapted. So, to understand the hydration mechanisms, indirect approaches are used. Semi-quantitative methods by X-ray Diffraction to follow-up the mayenite, calcium sulfate, syngenite and ettringite, ThermoGravimetric Analysis to measure degree of hydration and Mercury Intrusion Porosimetry to identify microstructural changes have been carried. The most important difficulty concerns the identification and quantification of amorphous phases such as slag, C-S-H and AH3. That is why a modelling approach is necessary to understand the role of each compound in the ternary mixture and in particular the obvious contribution of slag during rehydration test. This modelling approach increases knowledge of the physical and chemical phenomena in this ternary binder. It is useful to explain the observed macroscopic properties such as strength and helps to determine the kinetics of hydration in porous environment. Even if this model is still under development, it has allowed identifying the sequences of hydration (ettringitic binder reacts at very initial time, then anhydrite transforms into gypsum and slag reacts at long term) and confirms therefore that the reaction of slag is slow.

For the last 10 years, silicone-based admixtures have been successfully used for bulk waterproofing treatment of cementitious materials. However, a reduction in mechanical properties of treated materials is rather observed and becomes a major problem for the in-situ application. A new concept of a knowledge-based integral water repellent has been designed in such a way that the negative effect on mechanical properties is significantly reduced. The technology comprises the delayed release of the hydrophobic agent (silicone resin) which is achieved by encapsulation of the resin in SiO2 shell. A multidisciplinary research was conducted in order to propose a model of the delayed release and the silica shell reaction mechanism in cement paste. Therefore, a study on the microcapsules reaction in calcium hydroxide solution was conducted by means of FTIR, DSC-TGA, surface tension measurements and chemical analysis by ICP-OES. It was shown that microcapsules flocculate in presence of Ca2+, what appears to be the main factor that contribute to the delayed release of the resin.The influence of the microcapsules on Ordinary Portland (OPC) and Blast furnace slag (BFS) cement hydration process was compared with the emulsion of silane monomer and silicone resin. It was shown that the emulsion delays the setting and influences the early age hydration by prolonging the dormant period and decreasing the hydration heat. Cement microstructure and hydration products development was observed by SEM/ESEM. Quantitative analysis of hydration products was assessed by Rietveld analysis of XRD diffractograms. Emulsion induced a significant delay in the cement paste setting by changing the amount and morphology of ettringite and portlandite at very early age. Differently, microcapsules didn’t show any effect on these properties. Experimental work on relevant mortars is done in order to prove the concept of a delayed release as a solution towards the decrease in mechanical properties. The influence of the new additive on setting, volume change, dynamic E-modulus and the compressive strength was analysed. New analytical techniques (AutoShrink, Ultrasonic Pulse Velocity and ConSensor) in combination with traditional ones (Penetration resistance test and compressive strength on cubes) were used. Microcapsules have successfully lowered the negative impact of silanes on the compressive strength and dynamic Young’s modulus. Moreover, it was showed that the microcapsules slightly influence autogenous deformation by increasing the shrinkage of mortars.Microencapsulation of the silicone resin proved to be a promising solution for the bulk hydrophobic treatment of cementitious materials with no-influence on cement hydration. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Lors de la conservation des vins en bouteilles, des réactions d’oxydation prématurées peuvent se produire et les propriétés barrières à l’oxygène de l’obturateur en liège sont souvent mises en cause. À l’heure actuelle, aucune étude n’a permis de déterminer la structure interne du liège ou l’effet de l’hydratation sur ses propriétés mécaniques. Quant aux propriétés barrières à l’oxygène, l’étape limitante au transfert reste indéterminée ainsi que l’effet de la compression et le rôle de l’interface verre/liège. L’étude de la structure interne du liège par imagerie a permis de visualiser la macroporosité du matériau et de conclure que pour les qualités de liège étudiées, les lenticelles ne sont pas interconnectées. La caractérisation des propriétés mécaniques du liège a montré que le module de Young n’était pas affecté pour une humidité relative < 50 %. En milieu plus humide, ce dernier diminue à cause de la formation de clusters de molécules d’eau entre les chaines de polymères constituants les parois cellulaires. En comparant le comportement du liège brut avec celui d’autres obturateurs, un effet de la taille des particules de liège et du ratio liège/additifs utilisés dans ces obturateurs, a également été mis en évidence. Au regard du mécanisme de transfert de gaz, les mécanismes en jeu et en particulier l’étape limitante ont été clairement déterminés : il s’agit de la diffusion au travers des parois cellulaires selon la loi de Fick. L’effet de la compression du bouchon ne modifie pas significativement le transfert d’oxygène tandis que le rôle de l’interface verre/liège semble gouverner les transferts de gaz de l’extérieur vers l’intérieur de la bouteille. / During the post bottling aging, premature oxidation reactions could occur and the oxygen barrier properties of the stopper are often pointed out. Nowadays, the internal structure of this material or the effect of hydration on its mechanical properties are still undetermined. Moreover, regarding the barrier properties, the limiting step of the oxygen transfer was not yet fully understood as well as the effect of compression or the role of the glass/cork interface in a bottleneck. The study of the internal structure of cork stopper allowed us to visualize the macroporosity of the material and conclude that there is no interconnectivity between lenticels, for the two qualities studied. The effect of hydration on the mechanical properties of cork was also investigated. The results shown that the rigidity of the material was not significantly affected for relative humidity < 50 %. Above this hydration level, the Young’s moduli decrease due to clusters formation of water molecules. Comparing the natural cork behavior to other stoppers, an effect of the particle size and the ratio cork/additives used in these stoppers was also highlighted. Regarding the transport mechanism of gas through cork, the limiting step was clearly determined: it’s the diffusion through the cell wall according to a Fickian mechanism. The compression of the stopper does not have a significant impact on the effective diffusion coefficient of oxygen. However, the role of the glass/cork interface is really important and seems to govern the gas transfer from the surrounding atmosphere into the bottle.

Les propriétés mécaniques des ciments hydratés nécessitent d'être optimisées suivant la nature des ciments produits. Parmi les facteurs d'optimisation, l'ajout de sulfate de calcium destiné à réguler la réactivité de l’aluminate tricalcique (C3A), en quantité et en qualité, dans le ciment est un paramètre primordial. Enjeu industriel majeur, cette notion d'Optimum de sulfatage mérite aujourd'hui du fait de l'avancement des connaissances sur les mécanismes d'hydratation de chacune des phases du ciment qu'une étude lui soit entièrement consacrée. La démarche adoptée pour répondre à cette problématique a été l’étude de système simple que l’on a compliqué petit à petit. L’évolution de l’hydratation du ciment, de la porosité et des propriétés mécaniques du ciment ont été déterminés à différentes échéances. Le premier système étudié était le mélange C3S/gypse, l'objectif était de déterminer s'il existait un effet optimal du sulfate de calcium sur l'hydratation et les résistances mécaniques du C3S tel que présenté dans la littérature [1]. Les résultats ont montré qu’il n’existait pas d’optimum de sulfatage dans le système C3S/gypse mais qu’il existait un effet spécifique du sulfate de calcium sur l’hydratation et les propriétés mécaniques du C3S. L’adsorption des sulfates à la surface des C-S-H serait à l’origine de la modification du processus de germination croissance des C-S-H qui aurait pour conséquence l’augmentation du degré d’hydratation du C3S et des résistances en compression. Le deuxième système étudié était le clinker biphasique C3S/C3A cobroyé avec du semi-hydrate et avec du gypse. Un optimum de sulfatage a bien été observé, cet optimum se décale avec le temps vers les fortes teneurs en sulfate comme dans les cimenteries. L’optimum de sulfatage a été constaté lorsque l’hydratation du C3S, pendant la période accélérée, a lieu simultanément ou légèrement avant le pic exothermique dû à la forte dissolution du C3A et à la précipitation d’Afm. Il a été montré que la présence d’AFm pendant la période accélérée de l’hydratation du C3S, serait à l’origine de la modification observée de la microstructure de la pâte de ciment : la porosité augmente avec l’ajout du sulfate de calcium mais l’assemblage des hydrates est plus dense / The mechanical properties of hydrated cements need to be optimized according to the nature of cement products. Among the factors of optimization, the addition of calcium sulphate intended to regulate the reactivity of tricalcium aluminate (C3A), in quantity and quality in cement is an essential parameter.The advancement of knowledge on the mechanisms of hydration of each cement phase allows a study devoted entirely to the concept of optimum of sulphate. We studied simple system that we complicated and we studied the evolution of hydration, porosity and mechanical properties of cement at different age. The first system studied was the mixture C3S/gypsum, the objective was to determine whether there was an optimal effect of calcium sulfate on hydration and mechanical strength of C3S as presented in the literature [1]. The results showed there was not optimum sulfate in the C3S/gypsum system but there was a specific effect of calcium sulfate on the hydration and the mechanical properties of C3S. The sulfate adsorption on the C-S-H surface is the cause of the change nucleation and growth process of C-S-H. This has resulted in increasing hydration degree of C3S and compressive strength. The second system studied was biphasic clinker C3S/C3A ground with hemi-hydrate and gypsum. An optimum sulfate has been observed, which move out with time to high rate of sulfate. The optimum sulfate was observed when the hydration of C3S, during the accelerated period, takes place simultaneously or slightly before the exothermic peak due to the high dissolution of C3A and precipitation of AFm. We showed the presence of AFm during the accelerated hydration of C3S, is the cause of the microstructure modification in the cement paste: the porosity increases with calcium sulfate addition but the hydrate assembly is more dense.

Ce travail consacré à l’étude des différents paramètres influençant l’hydratation de la phase silicate principale du Ciment Portland Ordinaire (OPC) a été réalisé au Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB). Cette étude s’inscrit dans le cadre du projet « Crystal Growth Control » initié par BASF dans le but de contrôler et de prévoir le mieux possible l’hydratation du Ciment Portland Ordinaire. La dissolution de l’alite, comme celle du C3S pur, est rapide dans l’eau pure. La vitesse diminue avec l’écart à l’équilibre et la concentration en ions aluminates en solution. On observe également une adsorption sur la surface de l’alite de l’aluminium libéré par la dissolution. La germination et la croissance des C-S-H a été étudié d’une part, en présence d’aluminates en solution et d’autre part en présence de sels inorganiques connus pour être des accélérateurs de l’hydratation du ciment Portland Ordinaire. La présence d’aluminium ne modifie pas la germination initiale des C-S-H mais semble participer directement à l’origine de la période dormante du ciment. L’hydratation du C3S dans des solutions salines conduit à former pendant la germination initiale d’autant plus de C-S-H que la solution est concentrée. De plus la morphologie des germes est modifiée. Chaque germe doit contenir plus de matière en occupant moins de surface. La simulation de l’ensemble de la courbe d’avancement de l’hydratation observée dans les solutions de sels de nitrates et d’halogénures de calcium, sodium et potassium à l’aide du modèle de croissance par agrégation de particules cubiques confirme l’anisotropie au cours de la croissance des germes. La vitesse de croissance des C-S-H perpendiculairement à la surface des grains augmente avec la concentration et l’effet est très dépendant de la nature de l’anion. Ce comportement est à rapprocher des séries d’Hofmeister / This work devoted to study various parameters influencing hydration of silicate phase main Ordinary Portland Cement (OPC) was performed at the Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB). This study is part of the project "Crystal Growth Control" initiated by BASF in order to monitor and provide the best as possible the hydration of Ordinary Portland Cement. The dissolution of alite, like the pure C3S one, is fast in pure water. Speed decreases with deviation from equilibrium and the concentration of aluminates ions in solution. There is also an adsorption on the surface of the aluminum which is into the alite and released by dissolution. Germination and growth of C-S-H has been studied on the one hand, in the presence of aluminates ions within the solution and the other, in the presence of inorganic salts known to be accelerators of Ordinary Portland cement hydration. The presence of aluminum does not alter the initial germination of C-S-H but seems directly involved in the origin of the dormant period of cement. The hydration of C3S in salt solutions leads to the formation during the initial germination even more C-S-H that the solution is concentrated. In addition, the morphology of seeds is modified. Each seed must contain more material occupying less space. Simulation of the entire hydration progress curve observed in solutions of salts of nitrates and halides of calcium, sodium and potassium with the growth model based on the cubic particles aggregation confirms the anisotropy in the growth of seeds. The C-S-H perpendicular growth rate to the surface of the grains increases with the salt concentration and the effect is very dependent on the nature of the anion. This behavior is closer to the Hofmeister series