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In strongly correlated electron systems the intricate interplay between electronic correlation effects and the tendency to form bands leads to a wealth of fascinating physical phenomena. The theoretical description of such systems is extremely complex and cannot be tackled exactly, so that ingenious modelling based on approximations must be utilized. Experiments are of utmost importance in this regard, since they provide a way to test and verify models, or to help devise better ones. This Dissertation deals with strongly correlated uranium intermetallic systems. The interesting phases they can adopt include heavy fermion behaviour, unconventional superconductivity, hidden and multipolar order, and exotic induced magnetism. Here the hybridization between the 5f states and the conduction electrons drives the physics. The description of the 5f states is therefore of utmost importance. However, since there is no clear hierarchy of interactions like Coulomb repulsion, spin-orbit coupling, hopping and crystal-field, the modelling is difficult. This is in strong contrast to the more spatially localized 4f states of, e.g., cerium compounds. It is far from clear how to quantitatively describe the electronic structure of uranium intermetallics and whether, for example, an itinerant band approach or an impurity-type model, taking local degrees of freedom explicitly into account, would be a better starting point. In intermetallics, the situation is aggravated by the fact that the modelling lacks important pieces of information. This is not least due to the fact that understanding the formal valence, the filling of the 5f shell, and the relevant symmetries of the $5f$ electrons are experimentally demanding tasks. This Dissertation, therefore, aims at developing new methods and Ans\'atze in this direction. We use x-ray spectroscopy to investigate the electronic structure, and in particular element-specific Inelastic X-ray Scattering (IXS); resonant (RIXS) at the U M(5) edge and non-resonant (NIXS) at the U O(4,5) edge. Both methods are innovative. For the first time, valence band RIXS measurements with sufficient resolution (150 meV) can be carried out at the U M(5) edge to measure ff excitations in intermetallic uranium compounds. Their existence, if present, provides information about the formal valence or main atomic configuration that determines the symmetry. The orientation dependence of the mutipolar excitations in NIXS (with restrictions also in RIXS), in turn, provides information about the orbital occupation. Atomic full-multiplet calculations are indispensable here. In addition, photoelectron spectroscopy (PES) is applied, both in the soft as well as in the hard x-ray regime (HAXPES), to investigate the hybridization and localization of the 5f electrons. The energy dependence of the cross-sections allows to determine the orbital contributions in the valence band, so that parameters like, e.g., the double-counting correction for the LDA+DMFT calculations, performed by Prof. A. Hariki from the Osaka Metropolitan University, can be determined from tuning the calculations to the experimental data. This combination of PES and DFT+DMFT provides a reliable new quantitative insight into the number of electrons in the 5f shell and their degree of delocalization. We consider UGa(2) and UB(2), respectively, as benchmark localized and itinerant systems and investigate them with IXS and PES. UGa(2) is a high-moment ferromagnet, with U-U distances above the Hill limit, while UB(2) is paramagnetic and clearly below the Hill limit. We observe sharp multiplet excitations of the 5f2 configuration in the IXS spectra of UGa(2), but none in the spectra of UB(2). The comparison of the spectra with full-multiplet calculations shows that in UGa(2) the U 5f2 configuration dominates and, from the orientation dependence (RIXS and NIXS), the crystal-field ground state can be determined. We show that the magnetism of this compound is of the induced type. The cross-section based analysis of the valence band PES data with the LDA+DMFT approach shows that the filling of the 5f shell is similar in both compounds, but that the distribution among different configurations is considerably wider in UB(2). Also the time-dependent charge correlation functions of UGa(2) and UB(2) show a larger itinerancy in the latter compound. The peculiarity and novelty about this combined study is that a reliable quantitative description of the electronic structure is achieved. This allows, for the first time, an accurate estimation of the 5f occupation and a quantitative description of the U\ 4f core-level PES spectra. This study paves the way to a systematic classification of uranium intermetallics. We further investigate the substitution series URu(2-x)Fe(x)Si(2) with PES. The systematic study of isostructural and/or isoelectronic series of compounds is crucial in unveiling the origin of their physical properties. URu(2)Si(2) exhibits hidden-order as well as superconductivity, and becomes antiferromagnetic upon Fe doping. Fe substitution seemingly involves the application of chemical pressure to the system. We measure the U 4f PES core-level of the URu(2-x)Fe(x)Si(2) substitution series and observe a non-monotonic shift of spectral weight. We argue that, besides chemical pressure, the Fe density of states at the Fermi level also plays a central role and we propose and extended Doniach diagram where the two effects compete. We also measure NIXS, confirming that the ground state symmetry is a singlet or quasi-doublet of the 5f2 configuration. The magnetic properties must then be understood, as in UGa(2), in terms of induced magnetism. We extend our study of the UT(2)Si(2) compounds to the case where T = Os, Ir, Pt and Au, i.e. 5d transition metals. Although the T= 3d and 4d transition metal systems have been extensively investigated, the T = 5d compounds lack systematic studies. The comparison of the NIXS spectra with multiplet calculations shows that also here the 5f2 dominates, only for T= Au it is not so clear. The absence of a strong directional dependence impairs the identification of the ground state symmetry. Valence band hard x-ray PES allows to probe the transition metal 5d states directly. U 4f core-level hard x-ray PES gives a qualitative indication of the filling of the 5f shell across the series. We then focus on hexagonal UNi(2)Al(3) and apply NIXS. Like isoelectronic and isostructural UPd(2)Al(3), it is a prototypical U heavy-fermion compound, showing antiferromagnetic order and unconventional superconductivity. We observe a strong directional dependence of the NIXS spectra at low temperatures. The possible ground-state symmetries of the 5f2 configuration that fit the NIXS data are in contradiction to previous proposals from fits of the static magnetic susceptibility. We put forward a new crystal-field model that describes the high temperature magnetic susceptibility and the NIXS data at low temperatures, and that explains the magnetism.

Notre étude a porté sur la compréhension microscopique des mécanismes de déformation du polyamide 6 (PA6) à l’état massif. Par des traitements thermiques appropriés, on a obtenu un jeu d’échantillons présentant des microstructures semi-cristallines variées, avec différentes formes cristallographiques (allotropes : α, γ ou β), différents taux de cristallinité (de 24 à 35%), différentes périodes de l’empilement des lamelles cristallines (de 7 à 12nm), ceci pour deux masses moléculaires différentes. Les propriétés mécaniques en traction ont été caractérisées au-dessus et au-dessous de la transition vitreuse de la phase amorphe (Tg). Les différents matériaux présentent des différences notables de comportements. Le taux de cristallinité semble être le facteur prédominant au-dessus de Tg, mais d’autres facteurs sont à prendre en compte en dessous de Tg, comme la forme cristalline et la morphologie lamellaire (épaisseur et facteur de forme). Grâce à un dispositif expérimental fabriqué sur mesure, des essais de traction ont été suivis par diffusion des rayons X aux petits (SAXS) et grands angles (WAXS) sur la ligne D2AM, ESRF, pour caractériser les déformations à l’échelle des empilements lamellaires et à l’échelle de la maille cristalline. Dans les échantillons présentant principalement de la phase cristalline β, les lamelles tendent à s’orienter perpendiculairement à la direction de traction (TD). Ce mécanisme d’orientation local (que nous appelons « modèle de réseau de chaînes ») est induit par la transmission des contraintes par les chaînes amorphes reliant les lamelles cristallines adjacentes. L’allongement local est plus faible que l’allongement macroscopique dans les lamelles perpendiculaire à TD, ce qui implique que les lamelles inclinées doivent être cisaillées. De plus, la phase β se transforme en phase α aux fortes extensions. Dans les échantillons présentant principalement de la phase α (la plus rigide), au-dessus de Tg, dans le régime élastique, les chaînes tendent d’abord à s’orienter perpendiculairement à TD, ce qui implique que les lamelles s’orientent parallèlement à TD (« modèle de lamelles rigides »). Ensuite, dans le régime plastique, une majeure partie des lamelles se réoriente perpendiculairement à TD, comme dans le « modèle de réseau de chaînes », tandis qu’une fraction mineure reste orientée parallèlement à TD. Une morphologie fibrillaire fortement orientée est finalement obtenue pour tous les échantillons quelle que soit la température. / Mechanical properties of bulk polyamide 6 (PA6) have been studied in relation to microscopic deformation mechanisms. By applying various thermal treatments, sets of samples with different semi-crystalline microstructures, namely various crystalline allotropic forms (denoted α, γ and β) and different values of the crystallinity index (from 24 to 35%) and of the long period of the lamellar stacks (from 7 to 12 nm), have been obtained, for two different molecular masses. Mechanical properties have been measured in the linear (viscoelastic) and nonlinear (plastic) regimes below and above the glass transition of the amorphous phase (Tg). Differences of behavior have been observed depending on the microstructure. While the crystallinity index seems to be the predominant factor affecting the mechanical behavior above Tg, other structural parameters such as the crystalline form and the lamellar morphology (thickness and aspect ratio) have to be taken into account below Tg. Deformations at the scales of lamellar stacks and of the crystalline unit cell have been characterized by small and wide angle X-ray scattering (SAXS and WAXS) performed in-situ during tensile tests. In samples with predominantly β phase, lamellae tend to orient perpendicular to the tensile direction (TD). This orientation mechanism (which we denote as ‘Chain Network model’) is driven by the amorphous chains which transmit the stress between adjacent lamellae. The tensile strain in lamellar stacks perpendicular to TD is lower than the macroscopic tensile strain, which must be compensated by increased shear in inclined stacks. Also, at high extension ratios, the β phase transforms into α phase. In samples with predominantly α phase and above Tg, morphology changes are more complex. In a first step, chains orient perpendicular to TD, which implies that lamellar planes tend to orient parallel to TD, possibly due to their high aspect ratio (denoted as ‘Rigid Lamella’ model). In a second step, beyond the yield, a major fraction of crystallites then reorients normal to TD, i.e. chains themselves become parallel to TD, while a minor fraction remains oriented along TD. A highly oriented fibrillar morphology is ultimately obtained in all cases.

Ce travail de thèse a visé la préparation de matériaux biohybrides à base de poly (liquide ionique)s (PIL) et de polysaccharide, en l’occurrence la gomme de guar. Les chaînes de poly (1- [2-acryloyl éthyl] -3 bromure-méthylimidazolium (poly (AEMIBr)) ont été synthétisées par polymérisation contrôlée de type RAFT. Des homopolymères de DP élevé (jusqu'à 300) et de faible dispersité (inférieur à 1,19) ont été obtenus seulement en quelques heures dans l'eau. Ces PIL ont par ailleurs été utilisés comme macroagents de transfert pour générer différents copolymères à blocs en milieu homogène et en émulsion dans le but d’accéder à des nano objets autoassemblés. En effet, différentes morphologies ont été obtenues en s’appuyant sur lesconcepts de la PISA. De plus, des copolymères greffés de type guar-g-PIL ont finalement été construits en milieu liquide ionique.en utilisant des dérivés de guar macroagents de transfert Les PIL combinent à la fois les propriétés des IL (non-volatile, stabilité thermique et chimique, haute conductivité...) et celles des polymères en termes de renforcement mécanique, c’est pourquoi ils ont été exploités pour élaborer des matériaux biohybrides de haute performance. La stratégie envisagée dans ce travail réside sur l’exploitation de trois composants: (i) les chaînes de poly (AEMIBr), (ii) le guar et (iii) un liquide ionique: le chlorure de butylméthylimidazolium (BMIMCl). La voie expérimentale permettant l’obtention de tels matériaux est très simple et non dégradante puisqu’elle n’implique que des étapes de solubilisation de polymères en milieu IL. Les propriétés rhéologiques et thermiques de ces matériaux ont été évaluées. En outre, la morphologie interne, par des mesures de WAXS et SAXS, ainsi que le transport ionique ont été étudiés. Il en ressort que de multiples interactions synergiques sont formées entre le guar et les chaînes de PIL, en parallèle des interactions de type PIL/IL et guar/IL. Des ionogels possédant un haut module élastique (jusqu'à 30 000 Pa) et une stabilité thermique élevée (jusqu'à 310 °C) ont ainsi été obtenus. En particulier, la présence de PIL a permis d’améliorer de façon considérable la stabilité dimensionnelle des gels, en limitant complétement les phénomènes d’exudation rencontrés dans les systèmes binaires guar/IL. Il s’avère, de plus, que ces matériaux sont parfaitement homogènes à l’échelle d’observation des analyses SAXS et WAXS. Ces gels ioniques présentent d'excellentes propriétés de transport ionique (10-4 S/cm à 30 °C) grâce notamment à leur structuration interne continue. Cette famille des matériaux multicomposants à base de guar, présente un fort potentiel, notamment pour une utilisation en tant que gel électrolyte dans le domaine de l’énergie. / This Ph.D work focuses on the preparation of biohybrid materials based on poly(ionic liquid)s (PIL) and a polysaccharide, guar gum. Poly(1-[2-acryloylethyl]-3-methylimidazolium bromide (poly(AEMIBr)) chains were synthesized through RAFT polymerization. Homopolymers with DP up to 300 and dispersity below 1.19 were obtained within hours in water. High chain-end fidelity further allowed for PIL chain extension with various monomers and stable PIL-based nanoparticles with various morphologies using the PISA concept were achieved. A series of guar-g-PIL graft copolymers were finally constructed in IL using guar macroRAFT agents. As PILs combine the attributes emanating from IL molecules (non-volatile, thermally stable, conducting…) with the ones of polymers in terms of mechanical reinforcement, the resulting polymers were exploited to elaborate high performance biohybrid materials. The cornerstone of this subsequent work was based on the straightforward formation of three-component blends: (i) poly(AEMIBr), (ii) guar and (ii) ionic liquid: butylmethylimidazolium chloride (BMIMCl). The pathway to obtain such ternary blends is very simple, since it only implies successive polymer solubilisation steps in IL. The rheological and thermal properties of the resulting materials were investigated. Also, the internal morphology by WAXS and SAXS measurements as well as the ionic transport were studied. It appeared that strong synergistic hydrogen bonding are developed between guar and PIL chains in addition to PIL/IL and guar/IL interactions. Ionogels with high elastic modulus (up to 30 000 Pa) and high thermal stability (up to 310°C) were prepared. Importantly, addition of PIL significantly enhanced the dimensional stability of the resulting ionogels and overcame IL exudation encountered in IL/guar binary systems. SAXS and WAXS revealed a homogeneous morphology and the ionogels were proven to exhibit excellent conductive properties (10-4 S/cm at 30°C) thanks to their highly continuous morphology. The resulting sustainable multicomponent materials may find applications as gel electrolyte for biobattery systems or supercapacitors.

Les virus sont les entités biologiques les plus abondantes dans les océans (∼1031 particules). Ils colonisent tous les écosystèmes de la planète y compris les environnements extrêmement acides, chauds et salins, environnements où les archées sont les organismes dominants. Les virus infectant les Crenarchées hyperthermophiles présentent des morphologies exceptionnelles et aussi une très faible proportion de gènes possédant des homologues avec de fonction connue. Parmi ces virus, le virus ATV (Acidianus two-Tailed virus), infecte les archées hyperthermophiles du genre Acidianus. ATV a la propriété unique de présenter un important développement structural complètement indépendante de son hôte, à l'extérieur de celui-Ci. Les virions d'ATV développent de longues queues à chaque extrêmité de sa capside, mais seulement à des températures proches de celles de l'habitat de son hôte, 85°C. Le sujet de ma thèse a porté sur l'étude structurale de protéines du virion d'ATV. J'ai résolu la structure cristalline de la protéine ATV-273, qui possède un nouveau fold α/β. J'ai aussi déterminé la forme de l'enveloppe de cette protéine par SAXS. J'ai montré qu'il est possible de placer deux dimères d'ATV-273, observés dans la structure cristalline, dans cette enveloppe. Ce résultat est aussi en accord avec l'état d'oligomérisation en solution déterminé par chromatographie d'exclusion stérique couplée à la diffusion de la lumière. La fonction de cette protéine reste cependant inconnue. / Viruses are the most abundant biological entity in the oceans (∼1031 particles) and remarkably, viruses populate every ecosystem on the planet including the extreme acidic, thermal, and saline environments where archaeal organisms dominate. The viruses infecting hyperthermophilic Crenarchaea revealed exceptional morphologies and also a very low proportion of genes with recognizable functions and homologues. Among these viruses we find ATV (Acidianus two-Tailed virus). ATV is a virus infecting hyperthermophilic archaea of the genus Acidianus, which has the unique property of undergoing a major morphological development outside and independently of the host cell. Virions develop long tails at each pointed end of the initial lemon-Shaped particle, at temperatures close to those of the host natural habitat, 85 °C. The subject of my thesis has focused on the virion proteins of ATV. I have solved the crystal structure of ATV-273 that revealed a new α/β fold. I have also obtained a SAXS envelope where it is possible to fit two crystal dimers, in agreement with the oligomerization state in solution as determined by size-Exclusion chromatography coupled to multi angle light scattering. The function of this protein, however, could be not determined. Moreover, a negative staining electron microscopy model was obtained for the AAA+ ATPase ATV-618, which belongs to the MoxR familiy and presents sequence high similarity with the AAA-ATase RavA from Escherichia coli K12. I have shown that this thermostable AAA-ATPase enzyme assumes a hexameric ring organisation in the presence of ATP.

Eletrônica utilizando polímero em substituição ao silício é uma área de pesquisa recente com perspectivas econômicas promissoras. Compósitos de polímeros com partículas metálicas apresentam interessantes propriedades elétricas, magnéticas e ópticas e têm sido produzidos por uma grande variedade de técnicas. Implantação iônica de metais utilizando plasma é um dos métodos utilizados para obtenção desses compósitos condutores. Neste trabalho é realizada implantação de íons de ouro de baixa energia em PMMA utilizando plasma. O PMMA tem grande importância tecnológica sendo largamente utilizado como resiste em litografias por feixe de elétrons, raios-X, íons e deep-UV. Como resultado da implantação iônica de baixa energia em PMMA há formação de uma camada nanométrica de material condutor. Esse novo material, denominado compósito isolante-condutor, permite criar micro e nanodispositivos através de técnicas largamente utilizadas em microeletrônica. Medidas elétricas são realizadas in situ em função da dose de íons metálicos implantada, o que permite um estudo das propriedades de transporte desses novos materiais, que podem ser modeladas pela teoria da percolação. Simulações utilizando o programa TRIDYN permitem obter a profundidade e o perfil da implantação dos íons. São mostradas caracterizações importantes tais como Microscopia Eletrônica de Transmissão, Microscopia de Varredura por Tunelamento, Espalhamento de Raios-X a Baixos Ângulos, Difração de Raios-X e Espectroscopia UV-vis. Essas técnicas permitem visualizar e investigar o caráter nanoestruturado do compósito metal-polímero. Ainda como parte deste projeto, as camadas condutoras formadas no polímero são caracterizadas quanto à manutenção das suas características de elétron resiste. / Electronics using polymers instead of silicon is a recent research area with promising economic perspectives. Polymer with metallic particles composites presents interesting electrical, magnetic and optical properties and they have been produced by a broad variety of techniques. Metal ion implantation using plasma is one of the used methods to obtain conductor composites. In this work it is performed low energy gold ion implantation in PMMA by using plasma. PMMA has great technological importance once it is broadly used as resist in electron-beam, X-ray, ion and deep UV lithography. As a result of low energy ion implantation in PMMA, a nanometric conducting layer is formed. This new material, named insulator-conductor composite, can allow the creation of micro and nanodevices through well known microelectronics techniques. Electrical measurements are performed in situ as a function of metal ions implanted dose, which allows the investigation of electrical transport of these new materials, which can be modeled by the percolation theory. Simulations using TRIDYN computer code provide the prediction of depth profile of implanted ions. Important characterizations are showed such as Transmission Electron Microscopy, Scanning Tunneling Microscopy, Small Angle X-Ray Scattering, X-Ray Diffraction and UV-vis Spectroscopy. These techniques allow to visualize and to investigate the nanostructured character of the metal-polymer composite. Still as a part of this project, the conducting layers formed are characterized in relation to the maintenance of their characteristics as electron-beam resist.

Lisozima mostrou-se capaz, quando dispersa em certos meios orgânico-aquosos, de gerar sistemas pseudoplásticos que evoluem espontaneamente para redes de caráter viscoelástico. Esse fenômeno foi investigado neste estudo, para lisozima dispersa em uma série de misturas binárias contendo derivados de uréia como componente orgânico. Devido aos notáveis efeitos observados para um de tais derivados, a saber, tetrametiluréia (TMU), especial atenção foi dedicada aos sistemas contendo esse composto. O enfoque experimental incluiu espectroscopia Raman, microcalorimetria, reologia e espalhamento de raios X a baixo ângulo (SAXS). O trabalho envolveu o estudo dos sistemas orgânico-aquosos isolados e na presença de proteína. No primeiro caso, foi feita uma investigação espectroscópica e microcalorimétrica dos sistemas quanto a aspectos relativos à segregação de microdomínios na fase liquida e sua conseqüente relação com a deflagração da transição viscoelástica na proteína. Foram observadas descontinuidades nos valores de entalpias de excesso de mistura para o sistema TMU/água em torno de wTMU = 0,6, assim como padrões peculiares de comportamento espectral em torno dessa concentração da mistura binária. No segundo caso, os sistemas complexos de proteínas gerados foram investigados sob o ponto de vista morfológico e dinâmico, através das técnicas reológicas e de SAXS. Energias de ativação de fluxo determinadas na região sub-crítica, de comportamento Newtoniano, mostraram uma dependência exponencial direta com wTMU, indicando que mudanças estruturais nos fluidos complexos já ocorrem em regiões de composição do solvente bem abaixo da região de transição em wTMU = 0,6. Na região viscoelástica, 0,6<wTMU<0,9, ensaios de relaxação indicaram a presença de duas populações distintas. A tangente de perda (tg &#948; = G\"/G\') apresentou valores menores que a unidade para todos os casos, indicando o caráter \"solid-like\" das redes nas condições de ensaio. Apesar de seu caráter sólido, as redes mostram-se bastante flexíveis, suportando grandes deformações antes da ruptura, como inferido a partir da larga região viscoelástica linear. A variação nos módulos elástico (G\') e de perda (G\") com a composição do solvente indica a dependência do caráter viscoelástico com a fração de massa de TMU na mistura binária. Na região de baixo conteúdo de água (wTMU = 0,9), um aumento em G\" após a região viscoelástica linear é observado, indicando aumento da estruturação antes da ruptura da rede. As curvas de SAXS foram modeladas em seus fatores de forma e de interferência com uma equação unificada para objetos aleatoriamente distribuídos em um continuum. Os resultados permitiram a construção de um modelo, compatível com as demais evidências experimentais, segundo o qual as moléculas de lisozima encontram-se em duas conformações distintas nas matrizes: uma de conformação estendida e caráter fractal, predominante em wTMU > 0,6, com dimensão máxima de ca. de 160 &#197;, responsável pela interdigitação com espécies fractais vizinhas e uma espécie compacta, minoritária em wTMU > 0,6 (porém predominante em wTMU <0,6), com raio de giro de ca. 48 &#197;, presente nos microdomínios intersticiais aquosos da matriz. Verificou-se ainda a viabilidade de incorporação homogênea de uma metaloproteína, o citocromo-c, às matrizes de lisozima, sem perturbação significativa de sua morfologia, o que constitue um evento de potencial interesse biotecnológico. Os resultados deste trabalho trazem novos suportes experimentais à hipótese de correlação entre inversão na microconfiguração do meio solvente binário e deflagração do processo de transição sol-gel da proteína. / Lysozyme was found to be able, when dispersed in certain organic/aqueous media, to generate pseudoplastic systems that spontaneously evolve to three-dimensional networks with viscoelastic character. This phenomenon was investigated in this study, for lysozyme dispersed in a series of binary mixtures containing urea derivatives as the organic component. Due to the remarkable effects obtained in one of such derivatives, namely, tetramethylurea (TMU), special attention was given to systems containing that compound. The experimental approach included Raman spectroscopy, microcalorimetry, rheology and small angle X ray scattering (SAXS). The work involved the study of the organic/aqueous systems on their own and in the presence of protein. The former consisted of binary liquid mixtures that were spectroscopically and microcalorimetrically investigated as to aspects concerning microdomain segregation in the liquid phase and its consequent relationship with the threshold of the protein viscoelastic transition. Discontinuities in the excess enthalpy of mixture were observed for TMU/water system around wTMU=0.6, as well as peculiar spectral patterns around that same binary mixture concentration. The latter comprised complex protein systems that were investigated both under a morphological and dynamical point of view. Flow activation energies determined in the sub-critical (Newtonian) region showed an exponential increase with wTMU, indicating that structural changes in the comp]ex fluids are under way at solvent concentration regions well below that of the transition, at wTMU = 0.6. In the viscoelastic region, 0.6<wTMU<0.9, relaxation studies indicated the presence of two distinct populations. The loss tangent (tan &#948; = G\"/G\') presented values lower than the unity for all cases, indicating the solid-like character of the matrices, in the assay conditions. Despite their solid character the networks are quite flexible, standing large strains before rupture, as inferred from the large linear viscoelastic region. The variation in elastic (G\') and loss (G\") moduli with solvent composition indicates a dependence of the viscoelastic character on TMU mass fraction in the binary mixture. In the region of low water content (wTMU = 0.9), an increase in G\" after the LVR is observed, indicating increase in network structuring before rupture. SAXS curves were modeled with a unified equation for randomly distributed objects in a continuum. Results allowed the proposal of a model, which is compatible with the experimental evidence obtained through the other techniques in this work, according to which lysozyme molecules occur in two distinct conformations: one expanded and with fractal character, prevailing at wTMU > 0.6, with maximum dimension ca. 160 &#197; and interdigitated with neighbouring fractal species; and a compact conformation, of minor prevalence at wTMU>0.6 (but prevailing at wTMU < 0.6), with radius of gyration ca. 48 &#197;, present in the matrix microdomain interstices. It has also been verified the feasibility of homogeneous incorporation of cytochrome-c into the lysozyme matrices, an event of potential biotechnological interest. Results from this work bring further experimental support to our hypothesis on the correlation between microconfigurational inversion in the binary solvent medium and the sol-gel transition in the protein.

In dieser Doktorarbeit wird die Hypothese geprüft, ob Osteozyten einen direkten Einfluss auf die Knocheneigenschaften in ihrer unmittelbaren Umgebung haben. Der zentrale Experimentieransatz ist dabei die Korrelation der Organisation des Osteozytennetzwerks mit den Mineraleigenschaften des Knochens auf der Submikrometerebene. Es wird gezeigt, dass bereits die anfängliche Ausrichtung der Osteoblasten entscheidend für die Synthese von hoch ausgerichtetem Knochenmaterial ist. Die dabei entstehenden Osteozytennetzwerke sind so organisiert, dass die Osteozyten und ihre Zellfortsätze jeweils einen möglichst kleinen Abstand zum Knochenmineral haben. Deshalb wird vermutet, dass genau diese Netzwerkorganisation mitentscheidend ist, wie gut die Zellen das Mineral in ih-rer Umgebung beeinflussen können. Messungen der Knochenmineraleigenschaften auf Submikrometerebene mit Röntgenkleinwinkelstreuung bestätigen diese Vermutung. Dabei wird deutlich, dass Knochenmaterial in der Nähe der Osteozyten durch andere Mineraleigenschaften geprägt ist. Um zu klären, wie Osteozyten Mineral in ihrer direkten Umgebung verändern können, werden Mechanismen der passiven Mineralherauslösung aus der mineralisierten Oberfläche des Osteozytennetzwerks untersucht. Es wird gezeigt, dass kalziumarme ionische Lösungen unter physiologischen Bedingungen große Mengen von Kalzium-Ionen aus dem Knochen lösen und diese dann durch die Osteozytennetzwerkstrukturen diffundieren können. Zum Abschluss wurde medullärer Knochen von Hühnern als ein Modellsystem für rasanten Knochenumbau untersucht. Dieser spezielle Knochentyp dient den Hennen als labiles Kalziumreservoir und ermöglicht dadurch die tägliche Eierschalenproduktion. Experimente am medullären Knochen-material zeigen insbesondere die Bedeutung von weniger stabilen Mineralstrukturen die benötigt werden um den Knochen an den schnellen, sich wiederholenden Knochenauf- sowie Abbau optimal anzupassen. / This thesis aims to test the hypothesis whether osteocytes have a direct influence on bone material properties in their vicinity. In this regard, the concomitant ana-lysis of osteocyte network organization and bone ultrastructural properties on the submicron level is the central approach to answer this question. In this work, it is shown that already initial cell-cell alignment during the process of bone formation is crucial for the synthesis of highly organized bone. Furthermore it is proposed that the occurrence of highly ordered osteocyte networks visualized with confocal laser scanning microscopy (CLSM) has a strong impact on the ability of osteocytes to directly influence bone material properties. These highly organized networks are another consequence of initial cell-cell alignment and are found to be arranged such as to feature short mineral cell distances. Examination of sub-micron mineral properties with scanning small angle x-ray scattering (sSAXS) shows that bone material in the direct vicinity of osteocytes and their cell proc-esses shows different mineral properties compared to bone further away in the depth of the tissue. Moreover, mechanisms of passive mineral extraction from the mineralized surface of the osteocyte network, due to the treatment with calcium poor ionic solutions, are investigated. It is shown that this chemical process occurring under physiological conditions leads not only to the dissolution of considerable amounts of calcium, but also to efficient diffusion of these ions through the osteocyte network structures. Finally, medullary bone which is intended as a labile calcium source for daily egg shell formation in hens is used as a model system for rapid bone turnover rates. This bone type in particular indicates the importance of uniquely adapted, less stable mineral structures to fit the requirements for rapid bone resorption as well as reformation.

Funktionale organische Moleküle bergen ein hohes Potential für den Einsatz in zukunftsprägenden Technologien wie organischen Leuchtdioden (OLED), Solarzellen, Transistoren und Bio-Sensoren. Eines der Herstellungsverfahren beruht auf der Gasphasenabscheidung der Moleküle, die auf dem Substrat mittels Selbstorganisation zu dünnen Schichten wachsen. Auf Grund der komplexen Wechselwirkungen und des Einflusses der Schichtmorphologie auf die Funktionalität der dünnen Schichten stellt der Wachstumsprozess sowohl für die anwendungsorientierte als auch für die Grundlagenforschung eine hochinteressante und wichtige wissenschaftliche Herausforderung dar, mit der sich die vorliegende Arbeit auseinandersetzt. Die experimentellen Resultate und Konzepte, die in dieser Arbeit vorgestellt werden, leisten neue Beiträge für das Verständnis von organischem Wachstum. Der demonstrierte Einfluss von chemischer Modifikation auf verschiedene Aspekte des Strukturwachstums, wie z.B. auf die Filmrauigkeit, Kristallphasenreinheit und molekulare Diffusivität, zeigt zudem das hohe Potential dieser Methode zur Steuerung des organischen Wachstums. Aus den genannten Gründen kann diese Arbeit neue Impulse für die Erforschung und spätere Anwendung von funktionalen organischen Dünnschichtsystemen setzen. / Functional organic molecules are promising for the application in future relevant technologies such as organic light emitting diodes (OLEDs), solar cells, transistors and bio-sensors. One of the processing methods to fabricate organic devices is organic molecular beam deposition. In this process, the complexly interacting molecules grow via self-assembly as thin films on a substrate. Due to the close structure-property relationship, the growth process constitutes a highly interesting and important scientific challenge for both application oriented as well as fundamental research and is the topic of the present thesis. The experimental results and conceptual methods presented in this thesis contribute new stimuli to the understanding of the molecular self-assembly. The demonstrated influence of chemical tuning on various facets of structure formation, such as film roughness, crystal phase purity and molecular diffusivities, uncovers the strong potential of this approach for steering organic growth. Therefore, the present work has implications for future research and application of functional organic thin films.

Cette thèse présente une étude des solutions aqueuses de trois complexes de polyélectrolytes (PECs) modèles. Les PECs résultent de la complexation de deux polyélectrolytes linéaires de charge opposée: un polycation (le PDADMA) et trois polyanions de longueur de persistance non électrostatique distinctes: le polystyrene sulfoné (PSS), le poly(α-méthyl styrène sulfoné) (PαMSS) et l’acide hyaluronique (HA). En plus de l’influence de la rigidité intrinsèque des polyanions sur la formation et la structure des PECs, les effets de la force ionique et de la méthode de préparation des solutions aqueuses de PECs ainsi que l’influence de la concentration des solutions binaires de polyélectrolytes initiales ont également été abordés. Nous suggérons que le processus de complexation entre polycations et polyanions en régimes semidilué et concentré est analogue à une gélification. Il y a toutefois une différence entre les deux complexes qui est reliée à la différence de rigidité intrinsèque. / This PhD thesis presents a study of the aqueous solutions of three model polyelectrolyte complexes (PECs). PECs were formed between hydrophilic and highly charged linear macrocations of poly(diallyldimethyl ammonium) (PDADMA) and linear macroanions of distinct intrinsic persistence lengths: sulfonated polystyrene (PSS), sulfonated poly(α-methyl styrene) (PαMSS) and hyaluronate (HA). In addition to the effect of the macroion stiffness on the PEC formation and structure, those of the ionic strength and the way of preparing the PEC aqueous solutions as well as that of the concentration regimes of the initial PE aqueous solutions were also tackled. We suggest the complexation between macrocations and macroanions in the semidilute and concentrated regimes can be described as a universal gelation process. A difference between PDADMA-PSS and PDADMA-HA complexes is related to the primary self-assembling process and is associated with the distinct structural models for PECs.