Die vorliegende Dissertation beschäftigt sich mit der Herstellung und Charakterisierung von dünnen amorphen Metallschichten. Diese Materialklasse hat durch das Fehlen von klassischen mikrostrukturellen Fehlern wie Versetzungen oder etwa Korngrenzen Vorteile hinsichtlich der mechanischen Belastbarkeit oder beispielsweise Korrosionsbeständigkeit. Die binären Legierungen Ni-Zr und Cu-Ti wurden grundlegend in ihren Phasen-Gefüge-Eigenschaftsbeziehungen insbesondere in Abhängigkeit ihrer Zusammensetzung untersucht. Unter anderem wurden die Oberflächenrauheit und der spezifische elektrische Widerstand bestimmt und im materialwissenschaftlichen Kontext diskutiert. Das Hauptaugenmerk lag auf der Ermittlung der mechanischen Kennwerte wie E-Modul und intrinsische Eigenspannung. Die Kenntnis darüber ist notwendig, wenn in reproduzierbarer Weise Mikroröhren durch Aufrollen aus Dünnschichten dieses Materials hergestellt werden sollen. Eine solche Technologie setzt Eigenspannungsgradienten orthogonal zur Schichtebene voraus, so dass nach Ablösen vom Substrat sich eine Röhrengeometrie durch elastische Relaxation ergibt. In dieser Arbeit wurden die eigenspannungsgenerierenden Effekte in Abhängigkeit des Gefüges und der vorliegenden Phasen analysiert. Die gemessenen konkreten Werte wurden genutzt um erste Röhren gezielt herzustellen. Dabei zeigte sich, dass bereits mit geringem technologischem Aufwand die Röhren sich reproduzierbar und vorhersagbar in ihrer Geometrie fertigen lassen. / This dissertation is addressing the preparation and characterization of thin amorphous metallic films. That material class has its advantages concerning mechanical stability or corrosion resistance due to the lack of classic microstructural defects like dislocations or grain boundaries. Ni-Zr and Cu-Ti as binary alloys were examined thoroughly in their phase-microstructure-property relationships especially in dependency on chemical composition. Beside others the surface roughness and specific electrical resistivity was determined and discussed in material science context. The main focus was on investigation of mechanical characteristic values like Young’s modulus and intrinsic residual stresses. Knowledge on that issue is necessary, when microtubes are to be reproducibly fabricated out of thin films made of these materials. Such a technology requires a stress gradient perpendicular to the layer plane, which leads to a tube geometry after separating it from the substrate due to the effect of elastic relaxation. In the present research the stress generating effects are analyzed with respect to the microstructure and existent phases. The measured actual values were used to produce first test tubes. It is shown, that these tubes can be fabricated in a reproducible and foreseeable manner in geometry even with a low techno-logical effort.

This thesis explored how asphaltene and naphthenic amphiphile species influence the formation (morphology and size) and stability of heavy crude oil (bitumen) emulsions. It was experimentally shown that asphaltenes produce water-in-oil emulsions. Naphthenic amphiphiles on the other hand flip the emulsion morphology to oil-in-water. It was further demonstrated that the size and stability of these emulsions is influenced by physicochemical effects such as the pH, solvent-bitumen-water ratios, solvent aromaticity, and temperature. In view of these findings, the hydrophilic-lipophilic deviation (HLD) and net-average curvature (NAC) models were looked at as potential means for predicting the formation and stability of emulsions. Owing to the complexity of bitumen emulsions, however, the HLD and NAC models were instead tested against well-defined sodium dihexyl sulfosuccinate-toluene-water emulsions. The morphologies of these emulsions were predicted as a function of the formulation salinity whereas corresponding droplet sizes were predicted as a function of the continuous phase density and interfacial tension (γow). Emulsion stability trends were in turn predicted using a collision-coalescence-separation assumption. From this assumption, emulsion stability was expressed as a function of the emulsion droplet collision frequency and activation energy. The key parameters of the highly scrutinized activation energy term included the γow, interfacial rigidity, and critical film thickness. In applying the same modeling approach to the stability of other emulsions already published in the literature, it was found that the rigidity of adsorbed multilayer/liquid crystal films cannot yet be fully accounted for. This shortcoming was the reason for which only minimum stability times were reported for bitumen emulsions.

No description available.

Des anomalies dans la morphologie pelvienne, la posture du tronc et le contrôle de l’équilibre de jeunes filles atteintes de scoliose idiopathique de l’adolescence (SIA) ont souvent été l’objet d’études. Rares sont celles ayant distingué ces troubles en fonction de la sévérité de la déformation vertébrale. De plus, aucune n’a évalué à l’intérieur d’une même étude l’orientation et la distorsion pelvienne, l’asymétrie posturale et l’instabilité en position debout de sujets SIA. Une telle étude permettrait de comprendre le développement de la maladie et de mettre en évidence des facteurs de risque aidant au pronostic. L’objectif général de cette thèse est d’identifier des facteurs biomécaniques associés à la croissance osseuse, la posture et l’équilibre distinguant une SIA modérée d’une sévère. Les positions 3D de 14 repères prises sur 46 filles ayant une SIA droite (modérée et sévère) et 28 sujets témoins ont été captées pour quantifier la morphologie pelvienne et la posture. Un maintien en position debout de 64 s sur une plate-forme de force a aussi été enregistré afin d’évaluer leur équilibre. Les paramètres retenus sont les angles d’orientation pelvienne et du tronc; les distances entre la crête iliaque et S1 mesurant la distorsion pelvienne; la moyenne, l’amplitude et la vitesse du centre de pression (COP) en médiolatéral (ML) et antéropostérieur ainsi que la moyenne et l’amplitude du moment libre. Les différences entre les trois groupes (témoin, SIA modérée et SIA sévère) sont testées par des ANOVA et les relations entre l’angle de Cobb et les paramètres pelviens, posturaux ou d’équilibre, par des coefficients de corrélations. De plus, des régressions multiples exprimant l’angle de Cobb sont effectuées avec les paramètres pelviens, posturaux et d’équilibre afin de déterminer la classe de paramètres prédisant le mieux l’angle de Cobb. Aucune ANOVA n’est significative pour l’orientation pelvienne, bien que des différences de géométrie pelvienne soient notées entre les deux groupes de sujets SIA. Les SIA modérées ont un pelvis gauche moins profond que les SIA sévères et les sujets témoins, tandis que les SIA sévères ont un pelvis droit plus large d’environ 1,5 cm que celui des SIA modérées. Un coefficient de corrélation de -0,54 associe une rotation pelvienne droite à l’augmentation de la largeur de la crête iliaque. Au niveau postural, les SIA sévères démontrent des inclinaisons latérales et antérieures du tronc ainsi qu’une rotation axiale du haut du corps plus marquées que les SIA modérées. Les corrélations entre les paramètres posturaux, l’angle de Cobb et la morphologie pelvienne indiquent que l’attitude posturale est associée à la distorsion pelvienne dans tous les plans anatomiques, tandis qu’elle ne l’est que dans les plans sagittal et horizontal à l’angle de Cobb. Les différences retrouvées entre les deux groupes SIA concernant les troubles d’équilibre résultent en une augmentation de l’amplitude et de la vitesse du COPML. Une régression multiple de 0,896 est observée par l’emploi des paramètres pelviens, posturaux et d’équilibre, bien que ceux se rapportant à la distorsion pelvienne soient les mieux corrélés à l’angle de Cobb. Cette thèse permet de distinguer la morphologie pelvienne de sujets SIA sévères des modérées, soulignant la détection d’une anomalie de croissance avant que l’angle de Cobb ne soit élevé. Bien que les indices de croissance pelvienne soient davantage corrélés à ce dernier, c’est en considérant globalement la morphologie pelvienne, la posture et l’équilibre qu’une détermination précise de la sévérité d’une scoliose est réalisée. La mise en évidence de tels facteurs de prédiction de la SIA peut faciliter le pronostic d’une courbure. / The effect of adolescent idiopathic scoliosis (AIS) on pelvis morphology, body posture and standing balance in young girls has been studied many times. However, only few studies have distinguished the effect associated with moderate AIS from a severe one. Moreover, no one ever assessed within one investigation pelvis orientation and distortions, postural asymmetry and standing imbalance in AIS subjects. This would help understanding the evolution of the disease and to shed light on risk factors that would facilitate the prognostic. The aim of this thesis is to identify biomechanical factors related to bone growth, posture and balance which can distinguish a moderate AIS from a severe one. The 3D coordinates position of 14 body landmarks taken on 46 young girls with right AIS (moderate and severe) curvature and 28 control subjects is captured to quantify pelvis morphology and body posture. An upright standing is recorded during 64 s on a force plate to assess standing balance. From these data, the following parameters are calculated: orientation angle in all 3 planes for pelvis and trunk; distances between S1 and iliac crest to evaluate pelvis distortion; mean position, range and velocity of the center of pressure (COP) in mediolateral (ML) and anteroposterior axis and mean and range of the free moment. Differences between groups (control, AIS moderate and AIS severe) are tested by ANOVA and relationship between Cobb angle and pelvis, postural and balance parameters are calculated by correlation coefficients. Multiple regressions expressing Cobb angle by pelvis, postural and balance parameters are also carried out to determine which class of parameters is able to predict more effectively the Cobb angle’s curvature. No significant ANOVA is found for pelvis orientation, even though differences in pelvis geometry are noticed between the two groups of AIS subjects. Moderate AIS have a left pelvis with a depth less than severe AIS, whereas AIS severe have a larger right pelvis of 1,5 cm than moderate AIS. A correlation coefficient of -0,54 relates a right pelvis rotation to an increase in iliac crest’s width. About postural asymmetries, severe AIS shows lateral and anterior trunk bending and an axial rotation in the upper level of the trunk that are more pronounced compared to moderate AIS. Correlations between postural parameters, Cobb angle and pelvis morphology indicate a relationship between posture and pelvis distortion in all three planes, but only in the sagittal and horizontal plane between posture and Cobb angle. Differences in standing balance between the two groups of AIS show an increase in COPML range and velocity. A multiple regression of 0,896 is found for the Cobb angle using pelvis, postural and balance parameters. Parameters related to pelvis distortion correlate the most with Cobb angle (0,70). This thesis was able to differentiate severe AIS pelvis morphology from those of the moderate one. Pelvis morphology allows detecting a growth abnormality before the Cobb angle becomes high. Even if pelvis growth is more correlated to the Cobb angle, considering globally pelvis morphology, posture and standing balance will allow determining precisely the severity of AIS. Shedding light on such factors during the evolution of the disease helps an AIS curvature prognosis.

By enlarging the spatial and temporal spectral problems within a certain Lie algebra, a hierarchy of integrable couplings of the Kaup-Newell soliton equations is constructed. The recursion operator of the resulting hierarchy of integrable couplings is explicitly computed. The integrability of the new coupling hierarchy is exhibited by showing the existence of infinitely many commuting symmetries.

Curling deformation of thin elastic surfaces appears in numerous natural and man-made structures where a spontaneous curvature is present. In this thesis, we couple theoretical approaches and macroscopic experiments on elastic ribbons to understand the dynamics of curling of opened bio-membranes, motivated by the need to better understand recent microscopic observations during egress of Malaria infected red blood cells (MIRBC) and bursting of artificial polymersomes.In a first part, we study theoretically pore stability and curling propagation of an initially opened spherical bio-membrane. We model geometrically curling deformation as the revolution of a decentered Archimedean spiral, leading to a prescribed toroidal wrapping of the membrane. In this configuration, we show how the stability of a pore to curling depends strongly on both line-tension and shear elasticity and we discuss these results in relation to the curling of MIRBCs membranes. Moreover, taking into account viscous dissipations, the consequent dynamics we calculate agrees quantitatively well with experimental data obtained during opening of MIRBCs. Our approach shows in particular how the membrane dissipation resulting from the surface redistribution dominates curling dynamics over outer viscous dissipation.However, the complexity of the spherical geometry and the lack of detailed images in microscopic observations hamper the development of more accurate models where the coupling between flow and deformation is fully understood. Subsequently, we study in a second part the curling deformation of macroscopic naturally curved elastic ribbons in different viscous media and elastic conditions. At high Reynolds numbers, due to the tendency of ribbons to localize bending deformations when a curling front travels down the material, we show that curling reaches rapidly a constant propagating velocity. In this regime, the ribbon wraps itself into a compact roll whose size is predicted through the solitary wave solution of the associated Elastica. At low Reynolds numbers, however, closer to the hydrodynamic conditions of curling in microscopic membranes, we show that the strong lubrication forces induce a non-compact curling. The overall size of the spiraling ribbon increases in time leading to a temporal decrease of the released elastic power and therefore a consequent decrease in velocity. We discuss how such discovery sheds a new light on the modeling of curling in MIRBCs and polymersomes.

This thesis is twofold. In the first part, a proof of the interpolation inequality along geodesics in p-Wasserstein spaces is given and a new curvature condition on abstract metric measure spaces is defined. In the second part of the thesis a proof of the identification of the q-heat equation with the gradient flow of the Renyi (3-p)-Renyi entropy functional in the p-Wasserstein space is given. For that, a further study of the q-heat flow is presented including a condition for its mass preservation.

A theoretical explanation of the existence of lipid rafts in cell membranes remains a topic of lively debate. Large, micrometer sized rafts are readily observed in artificial membranes and can be explained using thermodynamic models for phase separation and coarsening. In live cells such domains are not observed and various models are proposed to describe why the systems do not coarsen. We review these attempts critically and show within a phase field approach that membrane bound proteins have the potential to explain the different behaviour observed in vitro and in vivo. Large scale simulations are performed to compute scaling laws and size distribution functions under the influence of membrane bound proteins and to observe a significant slow down of the domain coarsening at longer times and a breakdown of the self-similarity of the size-distribution function. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

<p>The central object of study of this thesis is inverse mean curvature vector flow of two-dimensional surfaces in four-dimensional spacetimes. Being a system of forward-backward parabolic PDEs, inverse mean curvature vector flow equation lacks a general existence theory. Our main contribution is proving that there exist infinitely many spacetimes, not necessarily spherically symmetric or static, that admit smooth global solutions to inverse mean curvature vector flow. Prior to our work, such solutions were only known in spherically symmetric and static spacetimes. The technique used in this thesis might be important to prove the Spacetime Penrose Conjecture, which remains open today. </p><p>Given a spacetime $(N^{4}, \gbar)$ and a spacelike hypersurface $M$. For any closed surface $\Sigma$ embedded in $M$ satisfying some natural conditions, one can ``steer'' the spacetime metric $\gbar$ such that the mean curvature vector field of $\Sigma$ becomes tangential to $M$ while keeping the induced metric on $M$. This can be used to construct more examples of smooth solutions to inverse mean curvature vector flow from smooth solutions to inverse mean curvature flow in a spacelike hypersurface.</p> / Dissertation

This thesis explored how asphaltene and naphthenic amphiphile species influence the formation (morphology and size) and stability of heavy crude oil (bitumen) emulsions. It was experimentally shown that asphaltenes produce water-in-oil emulsions. Naphthenic amphiphiles on the other hand flip the emulsion morphology to oil-in-water. It was further demonstrated that the size and stability of these emulsions is influenced by physicochemical effects such as the pH, solvent-bitumen-water ratios, solvent aromaticity, and temperature. In view of these findings, the hydrophilic-lipophilic deviation (HLD) and net-average curvature (NAC) models were looked at as potential means for predicting the formation and stability of emulsions. Owing to the complexity of bitumen emulsions, however, the HLD and NAC models were instead tested against well-defined sodium dihexyl sulfosuccinate-toluene-water emulsions. The morphologies of these emulsions were predicted as a function of the formulation salinity whereas corresponding droplet sizes were predicted as a function of the continuous phase density and interfacial tension (γow). Emulsion stability trends were in turn predicted using a collision-coalescence-separation assumption. From this assumption, emulsion stability was expressed as a function of the emulsion droplet collision frequency and activation energy. The key parameters of the highly scrutinized activation energy term included the γow, interfacial rigidity, and critical film thickness. In applying the same modeling approach to the stability of other emulsions already published in the literature, it was found that the rigidity of adsorbed multilayer/liquid crystal films cannot yet be fully accounted for. This shortcoming was the reason for which only minimum stability times were reported for bitumen emulsions.