Cette étude a pour objectif d’élaborer des mousses de géopolymère à macroporosité connectée pour le traitement des effluents liquides radioactifs. La première partie de ce travail a consisté à synthétiser des monolithes de géopolymères par moussage direct en utilisant le peroxyde d’hydrogène (H2O2) comme agent porogène. Celui-ci se décompose en milieu basique pour produire de l’oxygène et ainsi produire la mousse de géopolymère par nucléation/croissance de bulles d’oxygène jusqu’à épuisement du terme source et/ou prise du matériau. Pour stabiliser les bulles de gaz générées, l’ajout d’un tensioactif est nécessaire pour limiter les phénomènes de coalescence. L’influence de la concentration en H2O2, de la nature chimique du tensioactif et de la viscosité de la pâte sur la cinétique de production et sur les propriétés finales de la mousse ainsi produite a été étudiée. Les résultats montrent classiquement qu’une forte concentration initiale de H2O2 produit des mousses de forte porosité, avec des tailles de pores élevées et des propriétés mécaniques moindres. Par contre, le choix de la nature chimique du tensioactif a une très forte influence d’une part de la rhéologie de la pâte de géopolymère et d’autre part sur les propriétés du réseau poreux. En effet, par un choix approprié du tensioactif, il est possible d’obtenir des mousses de géopolymères à macroporosité fermée ou ouverte, avec des distributions en taille de pores plus ou moins étalées et de bonnes propriétés mécaniques. A l’issue de cette première étape, un monolithe de géopolymère à porosité ouverte a été fonctionnalisé par précipitation des particules d’hexacyanoferrate de cuivre connues pour être très sélectives vis-à-vis du césium. Les essais ont été réalisés en mode batch dans différents milieux (eau pure, eau douce et eau douce chargée de cations compétiteurs de charge en concentration importante). Les cinétiques et les isothermes d’adsorption du césium ont été déterminées sur une large gamme de concentration en césium (de l’état de trace jusqu’à 1000 ppm) et la mousse de géopolymère fonctionnalisée a montré des performances remarquables pour le piégeage sélectif du césium par rapport à une mousse non fonctionnalisée. En effet, les essais en milieu radioactif (trace de césium dans l’eau douce) ont montré que la valeur du coefficient de distribution (Kd) pour la mousse fonctionnalisée est de l’ordre 5.5 105 ml.g-1. / This study aims to develop geopolymer foams with connected macroporosity for the treatment of radioactive liquid wastes. The first part of this work was to synthesize geopolymer monoliths by direct foaming using hydrogen peroxide (H2O2) as blowing agent. It decomposes in a basic medium to produce oxygen and thus produces the geopolymer foam by nucleation and growth of oxygen bubbles until exhaustion of the source term and/or setting of the material. To stabilize the generated gas bubbles, the addition of a surfactant is necessary to limit coalescence phenomena. The influence of the H2O2 concentration, the chemical nature of the surfactant and the viscosity of the paste on the kinetics of production and on the final properties of the foam thus produced, was studied. The results conventionally show that a high initial concentration of H2O2 produces high porous foams, with high pore sizes and less mechanical properties. On the other hand, the choice of the chemical nature of the surfactant has a very strong influence on the one hand on the rheology of the geopolymer paste and on the other hand on the properties of the porous network. Indeed, by an appropriate choice of the surfactant, it is possible to obtain geopolymer foams with closed or open macroporosity, with pore size distributions more or less spread and with good mechanical properties. At the end of this first step, a well-connected geopolymer monolith was functionalized by precipitation of copper hexacyanoferrate particles known to be very selective with respect to cesium. The tests were performed in batch mode in different media (pure water, fresh water and fresh water loaded with competitor cations in high concentration). The kinetic and adsorption isotherms of cesium were determined over a wide range of cesium concentration (from trace to 1000 ppm) and the functionalized geopolymer foam showed remarkable performance for selective entrapment of cesium as compared to an unfunctionalized foam. Indeed, the tests in radioactive medium (trace of cesium in fresh water) have shown that the value of the distribution coefficient (Kd) for the functionalized foam is around 5.5 105 ml.g-1.

Os eletrodos de pasta de carbono modificados com Azul da Prússia foram preparados usando a voltametria cíclica, deposição a um potencial controlado e a deposição a dois potenciais controlados. O último método foi melhor e produziu eletrodos modificados com alta sensibilidade e estabilidade durante a redução catalítica de peróxido de hidrogênio. A composição da solução modificadora foi 3,0 mmol L-1 de FeCl3 e 2,0 mmol L-1 de K3[Fe(CN)6] em pH 2,0 com HCI. O sistema de eletrodos foi imerso na solução modificadora e + 0,4 V foi aplicado no eletrodo de trabalho durante 2 minutos. Depois, o potencial foi revertido para - 0,4 V por mais 2 minutos. O processo total foi repetido mais duas vezes. Além disso, para melhorar a estabilidade dos eletrodos de pasta de carbono modificados com Azul da Prússia (EPC-AP), estes foram ciclados em solução contendo 1,0 m mol L-1 de RhCl3, 0,05 mol L-1 de KCI e 0,02 mol L-1 de HCI na faixa de potencial - 0,4V ≤ Eapl ≤ 0,6V a 60 mV s-1 (50 ciclos). Estes eletrodos, denominados de EPC-AP-Rh, foram secos a temperatura ambiente por 24 horas antes de serem utilizados. Os EPC-AP-Rh apresentaram boa estabilidade durante sucessivos ciclos, com os picos anódico e catódico, referentes a 0,30 V e 0,18 V inicialmente atribuídos para um processo redox envolvendo Branco da Prússia / Azul da Prússia. Cálculos com (Ep,a + Ep,c / 2), é 0,24 V. Em solução tampão citrato de potássio / ácido cítrico contendo 0,5 mol L-1 de KCI, pH 6,1, as correntes de picos variam linearmente com a velocidade de varredura 0,025 Vs-1 ≤ ν ≤ 0,400 V s-1 mostrando que o processo é governado por difusão de íons do eletrólito suporte para a superfície do eletrodo (durante a etapa de redução) ou do eletrodo para a solução (durante a etapa de oxidação) para manter a eletroneutralidade. O excesso superficial foi 4,3 10-8 mol cm-2, calculado usando a carga anódica obtida pelo voltamograma cíclico, depois da subtração do fundo de carga referente a um eletrodo não modificado de pasta de carbono em solução eletrólito suporte (1,0 x 10-3 mol L-1 de RhCl3, 0,05 mol L-1 de KCI e 0,02 mol L-1 de HCI, ν = 60 mV s-1). O eletrólito suporte usado para detecção para determinação de peróxido de hidrogênio foi o tampão10 mmol L-1 de citrato de potássio/ 2 mmol L-1 de ácido cítrico, pH 6,1 (força iônica= 0,16 mol L-1) contendo 0,5 mol L-1 de KCI. A ausência deste eletrólito ou a presença de íons fosfatos diminui a estabilidade deste sensor. Peróxido de hidrogênio foi determinado a 0,04 V (vs EAg/AgCI, KCI sat) na faixa linear de 5,1 x 10-5 mol L-1 a 8,6 x 10-4 mol L-1 com sensibilidade média de 1,4 ± 0,2 A mol-1 L cm-2 e limite de detecção de (2,5 ± 0,02) x 10-5 mol L-1. Neste potencial aplicado a contribuição da corrente de redução do oxigênio foi de 8,0 % na presença de 1,0 mmol L-1 de H2O2. Curvas analíticas obtidas durante a determinação de peróxidos de hidrogênio ao longo de 5 dias, cada curva analítica representa uma média de 6 curvas amperométricas consecutivas, que desempenhou em cada dia, apresentando uma diminuição de somente 27% na sensibilidade do eletrodo modificado. Quando fora de uso o eletrodo foi armazenado em solução 0,5 mol L-1 de KCI. A um potencial aplicado de 0,04 V não foi detectada uma interferência do mediador ou oxidação direta do ácido úrico. A interferência de ácido ascórbico foi apenas significativa para potenciais iguais ou superiores a 0,060 V. / Prussian Blue carbon paste modified electrodes were prepared using cyclic voltammetry and deposition atone and two controlled potentials. The last method was the best and produced modified electrodes with higher sensitivity and stability during the catalytic reduction of hydrogen peroxide. The composition of the modifying solution was 3.0 mmol L-1 FeCl3, 2.0 mmol L-1 K3[Fe(CN)6] in pH 2.0 with HCI. The electrode system was immersed in the modifying solution and + 0.4 V was applied to the working electrode during two minutes. After, the potential was just reverted to - 0.4 V once more two minutes. The total process was repeated twice. Further, to improve the stability of the Prussian Blue carbon paste modified electrodes (PB-CPME), they were cycled in a solution containing 1.0 mmol L-1 RhCl3, 0,05 mol L-1 KCI and 0.02 mol L-1 HCI in a - 0.4 ≤ E ≤ 0.6 V potential range at 60 mV s-1 (50 cycles). These electrodes, denominated of Rh-PBCPME, were dried at ambient temperature during 24 hours before use. The Rh-PBCPME shows good stability during successive cycles, with anodic and cathodic peaks recorded at 0.30 V and 0.18 V being attributed to a redox process involving Prussian White / Prussian Blue couple. Em, calculated as (Ep,a + Ep,c/2), is 0.24 V. In potassium citrate/ citric acid buffer solution containing 0.5 mol L-1 KCI, pH 6.1, the peak currents changed linearly with the square of sweep velocity in the range 0.025 Vs-1 ≤ v ≤ 0.400 Vs-1 showing that the process is governed by ion diffusion from support electrolyte to the electrode surface (during the reduction step) or from the electrode to the solution (during the oxidation step) to ensure the electroneutrality rule. The modifier surface excess was 4.3 x 10-8 mol cm-2, calculated using the anodic charge obtained from cyclic voltammograms, after subtraction of the background charge recorded with an unmodified carbon paste electrode in an electrolyte support solution (1.0 mmol L-1 RhCl3, 0.5 mol L-1 KCI and 0.02 mol L-1 HCI, v = 60 mV s-1). The supporting electrolyte used to detection of hydrogen peroxide was 10 mmol L-1 potassium citrate/ 2 mmol L-1 Citric acid buffer, pH 6.1 (ionic strength = 0.16 mol L-1) containing 0.5 mol L-1 KCI. The absence of this electrolyte or the presence of phosphate ions decreased the stability of the sensor. Hydrogen peroxide was detected at 0.04V (vs EAg/AgCI, KCI sat) in 5.1 x 10-5 - 8.6 x 10-4 mol L-1 linear range with sensitivity of 1.4 ± 0.2) A mo1-1 L cm-2 and detection limit of (2.5 ± 0.02) x 10-5 mol L-1. At this applied potential the contribution of oxygen reduction current was 8.0 % in the presence of 1.0 mmol L-1 H2O2. Analytical curves obtained during hydrogen peroxide detections along 5 days, ach one of them representing an average of 6 consecutive amperometric analytical curves, carried out in the same day, showed a decrease of only 27 % in the sensitivity of the modified electrodes. When was not using the electrode was kept, 0.5 mol L-1 KCI. At 0.04 V applied potential no interference was detected due to mediated or direct oxidation of uric acid. The interference of ascorbic acid was only significant to 0.060 V or higher applied potentials.

Dans une première partie, la structure électronique de deux membres de la famille des Analogues de Bleu de Prusse (ABP) a été inspectée à l'aide de méthodes basées sur la fonction d'onde. Dans l'ABP NiFe, un changement du couplage magnétique a été mis en évidence lors d'une déformation structurale locale. Basé sur les résultats obtenus pour l'ABP CoFe, un rôle clé dans le processus photomagnétique observé dans ce matériau est attribué aux lacunes cristallines. Dans une deuxième partie, un développement méthodologique a été mené jusqu'à l'implémentation de la méthode FRACCIS (FRAgmented Contracted Configuration Interaction of Single excitations). Elle permet de concentrer l'effort numérique sur un petit nombre de déterminants physiquement importants. De plus, elle constitue un outil d'analyse pour mesurer l'importance de certaines excitations dans le système inspecté. L'application à (H2)2 et C4H6 montre qu'une réduction majeure de l'espace d'IC est possible en gardant une bonne précision par rapport aux valeurs de référence. Ce travail contribue aux efforts vers l'analyse rationnelle de la corrélation électronique. / In the first part, the electronic structure of two members of the family of Prussian Blue Analogues (PBA) has been inspected using wave function-based methods. The NiFe PBA exhibits a change of the magnetic coupling under a local structural deformation. Based on the results obtained for the CoFe PBA, a key role in the photomagnetic process observed in this material is attributed to the crystal vacancies. In a second part, a methodological development has been carried out and has lead to the implementation of the FRACCIS method (FRAgmented Contracted Configuration Interaction of Single excitations). It allows to concentrate the numerical effort on a small number of physically relevant determinants. Furthermore, it constitutes an analysis tool to measure the importance of certain excitations in the inspected system. The application to (H2)2 et C4H6 shows that a major reduction of the CI space is possible while keeping good accuracy with respect to reference values. This work contributes to the efforts towards a rational analysis of electronic correlation.

<p>Materials prepared on the nanoscale often exhibit many different properties compared to the same materials in their bulk-state. Interest in nanostructured materials has increased because of these properties in fields such as microelectronics, catalysis, optics and sensors. This increased interest in nanostructured materials calls for new and more precise fabrication techniques.</p><p>This thesis describes how to use the porous anodic aluminium oxide as a template for the fabrication of a variety of nanostructured materials. Palladium and copper nanoparticles were deposited along the pore walls in anodic aluminum oxide using electroless deposition and atomic layer deposition. In both cases, it was possible to control the size of the nanoparticles by carefully monitoring the deposition parameters. The thesis also describes how Prussian blue nanoparticles and nanotubes can be fabricated using the anodic aluminium oxide as a template. The deposition of Prussian blue was performed by a sequential wet-chemical method. By using atomic layer deposition, it was also possible to deposit thin films of amorphous Nb2O5 on the pore walls. When the template was removed by etching, freestanding nanotubes were obtained. The anodic aluminium oxide membrane was also used as a mask for high energy (MeV) ion irradiation of an underlying substrate. The tracks produced were etched away with hydrogen fluoride. In this way, it was possible to transfer the highly ordered porous pattern from the mask onto other oxides such as SiO2 and TiO2.</p><p>All fabricated structures were characterized using a variety of analysis techniques: scanning electron microscopy for evaluating sample morphology; transmission electron microscopy for better resolved investigations of the morphology; X-ray diffraction to assess crystallinity; energy dispersive spectroscopy and X-ray fluorescence spectroscopy to determine the elemental composition and identify possible contaminants.</p><p>The general aim of the work described in this thesis has been to create a set of tools for use in the fabrication of a variety of nanostructured materials, whose dimensions composition can be tailored by selecting appropriate fabrication methods and parameters.</p>

Materials prepared on the nanoscale often exhibit many different properties compared to the same materials in their bulk-state. Interest in nanostructured materials has increased because of these properties in fields such as microelectronics, catalysis, optics and sensors. This increased interest in nanostructured materials calls for new and more precise fabrication techniques. This thesis describes how to use the porous anodic aluminium oxide as a template for the fabrication of a variety of nanostructured materials. Palladium and copper nanoparticles were deposited along the pore walls in anodic aluminum oxide using electroless deposition and atomic layer deposition. In both cases, it was possible to control the size of the nanoparticles by carefully monitoring the deposition parameters. The thesis also describes how Prussian blue nanoparticles and nanotubes can be fabricated using the anodic aluminium oxide as a template. The deposition of Prussian blue was performed by a sequential wet-chemical method. By using atomic layer deposition, it was also possible to deposit thin films of amorphous Nb2O5 on the pore walls. When the template was removed by etching, freestanding nanotubes were obtained. The anodic aluminium oxide membrane was also used as a mask for high energy (MeV) ion irradiation of an underlying substrate. The tracks produced were etched away with hydrogen fluoride. In this way, it was possible to transfer the highly ordered porous pattern from the mask onto other oxides such as SiO2 and TiO2. All fabricated structures were characterized using a variety of analysis techniques: scanning electron microscopy for evaluating sample morphology; transmission electron microscopy for better resolved investigations of the morphology; X-ray diffraction to assess crystallinity; energy dispersive spectroscopy and X-ray fluorescence spectroscopy to determine the elemental composition and identify possible contaminants. The general aim of the work described in this thesis has been to create a set of tools for use in the fabrication of a variety of nanostructured materials, whose dimensions composition can be tailored by selecting appropriate fabrication methods and parameters.

How do states win wars against other states? We have three explanations. By selection, states enter more winnable wars. By warfighting, states use negative inducements so enemies fear fighting. By peacemaking, states use positive inducements so enemies hope for settling. This dissertation investigates peacemaking. It theorizes that states optimally produce influence only if they efficiently combine warfighting negative and peacemaking positive inducements. It hypothesizes that using some peacemaking on average improves outcomes verses using none. The dissertation tests this with a statistical analysis that measures peacemaking as law of war compliance and estimates effects on all inter-state outcomes from 1899 to 1991. It finds that compliance likely on average improves immediate military and final political relative outcomes. This dissertation also tests peacemaking in four case studies from the Franco-Prussian War of 1870-1871 and World War II. These case studies find that state peacemaking to enemy states, allies, leaders, troops, and civilians probably on average improves absolute war outcomes. These complementary and independent empirical results provide unprecedented support for the peacemaking explanation of how states improve inter-state war outcomes. To succeed, states should be prudent by selection, fierce in warfighting, and principled for peacemaking. / Government

Disertacijoje aprašoma prūsų kalbos kirčiavimo sistema, galimà atsekti iš šaltinių (visų pirma III prūsų kalbos katekizmo, teikiančio daugiausia akcentologijos duomenų) rašybos. Siekiama atkurti kiek įmanoma išsamesnį sinchroninį sistemos vaizdą ir nustatyti galimas diachronines jos raidos tendencijas. Kritiškai įvertinus visas iki šiol paskelbtas prūsų kalbos akcentologijos ir akcentografijos teorijas, pirmajame tyrimo etape apibrėžiami kirčiuoto skiemens nustatymo iš šaltinių rašybos principai, įvertinamas tokių mokslinėje literatūroje prūsų kalbai postuluojamų reiškinių kaip Saussure'o-Fortunatovo ar Kortlandto dėsniai realumas. Kirčiavimo sistemos analizėje, laikantis morfologinės akcentologijos principų, nustatomos kirčiavimą lemiančios paliudytų prūsų kalbos žodžių morfemų akcentinės savybės, žodžiai klasifikuojami į akcentines paradigmas, analizuojamas kirčio vaidmuo žodžių daryboje. Sinchroniniais metodais atkurta sistema nuosekliai lyginama su giminiškų kalbų (visų pirma lietuvių ir slavų) kirčiavimo sistemomis, konstatuojami jų sutapimai ir motyvuojami skirtumai. / The dissertation contains a description of the accentual system of Old Prussian as evidenced by the orthography of Prussian written monuments, particularly that of the Third Catechism (which abounds the most in accentological data). An attempt is made to reconstruct, as comprehensively as possible, the synchronic state of the accentual system in question, as well as to identify any possible trends in its diachronic development. At the first stage of research, upon a critical examination of all the theories dealing with Old Prussian accentology and accentography published to date, the methods of identifying the stressed syllable based on the orthography of the written monuments are outlined. The validity of Saussure-Fortunatov’s and Kortlandt’s laws, which have been postulated in the scholarly literature on Old Prussian, is subjected to a re-evaluation. Then, an analysis of the accentual system is undertaken, in adherence to the principles of morphological accentology, in order to determine the accentual properties of the Old Prussian morphemes conditioning the stress of the attested words, as well as to classify the words by accentual paradigm and to elucidate the role of stress in word-formation. This reconstructed synchronic system is then thoroughly confronted with those of the related languages (primarily Lithuanian and Slavic) to demonstrate the correspondences and to account for the discrepancies between them.

This dissertation presents chemical sensors that are based on an emerging optical fiber sensing technology for the determination of the presence and concentration of hydrogen peroxide (H2O2) at low concentrations. The motivation to determine hydrogen peroxide lies on the fact that this chemical species is generated as a by-product of the operation of hydrogen-based polymer electrolyte membrane fuel cells (PEMFCs), and the presence and formation of this peroxide has been associated with the chemical degradation that results in low durability of PEMFCs. Currently, there are no techniques that allow the hydrogen peroxide to be determined in situ in PEMFCs in a reliable manner, since the only report of this type of measurement was performed using electrochemical techniques, which can be affected by the environmental conditions and that can alter the proper operation of the PEMFCs. The sensors presented in this dissertation are designed to detect the presence and quantify hydrogen peroxide in solution at the conditions at which PEMFCs operate. Since they are made using fused silica optical fibers and are based on a spectroscopic technique to perform the detection of H2O2 , they are not affected by the electromagnetic fields or the harsh chemical environment inside PEMFCs. In addition, they are able to still detect the presence of H2O2 at the operating temperatures. The construction of the sensing film on the tip of an optical fiber and its small size (125 µm diameter), make the sensors here developed an ideal solution for being deployed in situ in PEMFCs, ensuring that they would be minimally invasive and that the operation of the fuel cell would not be compromised by the presence of the sensor. The sensors developed in this dissertation not only present design characteristics that are applicable to PEMFCs, they are also suitable for applications in other fields such as environmental, defense, and biological processes. / Graduate / 0548 / 0756 / 0791 / jfbotero@gmail.com

This dissertation presents chemical sensors that are based on an emerging optical fiber sensing technology for the determination of the presence and concentration of hydrogen peroxide (H2O2) at low concentrations. The motivation to determine hydrogen peroxide lies on the fact that this chemical species is generated as a by-product of the operation of hydrogen-based polymer electrolyte membrane fuel cells (PEMFCs), and the presence and formation of this peroxide has been associated with the chemical degradation that results in low durability of PEMFCs. Currently, there are no techniques that allow the hydrogen peroxide to be determined in situ in PEMFCs in a reliable manner, since the only report of this type of measurement was performed using electrochemical techniques, which can be affected by the environmental conditions and that can alter the proper operation of the PEMFCs. The sensors presented in this dissertation are designed to detect the presence and quantify hydrogen peroxide in solution at the conditions at which PEMFCs operate. Since they are made using fused silica optical fibers and are based on a spectroscopic technique to perform the detection of H2O2 , they are not affected by the electromagnetic fields or the harsh chemical environment inside PEMFCs. In addition, they are able to still detect the presence of H2O2 at the operating temperatures. The construction of the sensing film on the tip of an optical fiber and its small size (125 µm diameter), make the sensors here developed an ideal solution for being deployed in situ in PEMFCs, ensuring that they would be minimally invasive and that the operation of the fuel cell would not be compromised by the presence of the sensor. The sensors developed in this dissertation not only present design characteristics that are applicable to PEMFCs, they are also suitable for applications in other fields such as environmental, defense, and biological processes. / Graduate / 0548 / 0756 / 0791 / jfbotero@gmail.com

Univ., Diss.--Frankfurt (Main), 2003. / Literaturverz. S. [317] - 356.