The surface tension of solid commercially pure nickel was determined by the force measurement technique using fine wires as proposed by Udin, Shaler, and Wulff. Grain boundary measurements were also made on the same metal. After finding experimentally that tests in a vacuum of approximately 5 x 10⁻⁵ mm Hg were unsuccessful because of the high power vapour pressure of nickel at high temperatures, similar tests were made in helium and argon atmospheres, the pressure being kept constant at 760 mm Hg during the experiments. The average surface tension of nickel in argon was found to be 2220 ± 300 dynes per centimeter for a temperature range from 1370°C to 1390°C. The relative grain boundary energy of solid nickel was determined by measuring the dihedral grain boundary groove angles of thermally etched nickel. The interferometric method developed by Hilliard and Harrold was used for this purpose. An average value of 161 degrees was found for the dihedral angle. The grain boundary energy was calculated to be 740± 300 dynes per centimeter. Examination of thermally etched nickel surfaces was inconclusive with respect to physical evidence for dislocation. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

La question de l'eau constitue à l'heure actuelle un enjeu majeur pour nos sociétés. Bien qu'il s'agisse d'une ressource renouvelable, son cycle naturel est soumis à de fortes pressions issues tant de l'activité humaine que des modifications climatiques.Le débit des fleuves constitue une des variables clefs du cycle de l'eau. Sa quantification implique des mesures in situ lourdes. De ce fait, son suivi à l'échelle globale reste problématique, et les techniques de télédétection peuvent représenter un atout majeur. Les techniques satellitaires optiques et radar ne peuvent actuellement que mesurer les variables de surface et n'accèdent pas aux paramètres de fond des cours d'eau. Ce travail propose une méthode d'estimation de ces paramètres hydrauliques de fond à partir des seules mesures des variables de surface, en vue de l'estimation du débit. Cette méthode a été validée sur des données simulées exactes et une étude de sensibilité au bruit de mesure a été menée sur des données simulées bruitées et sur des données réelles.Le second volet de ce travail porte sur le potentiel de l'interférométrie radar temporelle à mesurer la variable de vitesse de surface des fleuves. Une campagne de mesure aéroportée a été réalisée sur le Rhône (ONERA-Cemagref) et a montré des résultats concordants avec les mesures de vitesses réalisées in situ par ADCP. En revanche, le modèle de rétrodiffusion M4S, testé dans le cadre de cette thèse, est apparu peu adapté aux scènes fluviales : il s'avère extrêmement sensible aux conditions de vent, ce qui peut s'expliquer par une faiblesse dans la modélisation des caractéristiques des surfaces de fleuves. Dans le cadre du programme SWOT (NASA-CNES), nous avons développé une méthode de mesure in situ de la rugosité des surfaces fluviales. Validée lors de mesures en laboratoire, cette méthode a été mise en œuvre sur le Rhône, et a ainsi permis de caractériser la surface et l'influence de l'intensité du vent sur les paramètres de rugosité. / The water issue is currently a major challenge for our societies. Even if water is a renewable resource, its natural cycle supports great stresses, both human activity and climate change.River discharge is a key variable of the water cycle, whose quantification requires heavy field measurements. Therefore the global monitoring of river discharge remains problematic and satellite remote sensing techniques could be a major asset. Earth Observation radar techniques are currently limited to the measurement of surface variables and cannot measure river bottom hydraulic parameters. The current study proposes a method to estimate these parameters from surface variables, in order to estimate the river discharge. This method has been validated on exact simulated data and its robustness to measurement noise has been studied on noisy simulated data and on real data.The second part of this work explores the abilities of radar along-track interferometry to measure river surface velocity. Velocity measurements carried out on the Rhône river during an airborne campaign (ONERA-Cemagref) show a strong consistency with ADCP field measurements. M4S backscattering model, tested in the framework of this study, is poorly adapted to river scenes : it appears to be extremely sensitive to wind intensity which could be explained by a poor modeling of surface roughness. As part of the SWOT mission program (NASA-CNES) a method allowing in situ characterization of river surface roughness has been developed. It was validated under laboratory controlled conditions. It was implemented on the Rhône river to characterize water surface and quantify the influence of wind intensity on the water surface roughness parameters.

Surface microtopography affects fundamental hydrologic processes including infiltration and soil-water percolation at different scales. By means of studying the unsaturated flow, this thesis research is aimed to evaluate the effects of surface microtopography on wetting front moving patterns for rough soil surfaces through both experimental study and HYDRUS modeling. Additional influential factors such as rainfall intensity and soil type are also considered. Laboratory-scale infiltration and unsaturated flow experiments were conducted for different microtopographic surfaces, rainfall intensities, and types of soil; and two- and three-dimensional numerical modeling was conducted under the same conditions. The simulated and observed wetting front distributions were compared in this combined experimental and modeling study. It was found that a uniformly distributed wetting front was eventually achieved although soil surfaces had dissimilar topographic characteristics. However, the timing to reach the uniform flat wetting front varied, depending on surface microtopography, soil hydraulic properties, and boundary conditions. / Department of Civil Engineering, North Dakota State University / National Science Foundation (Grant No.EAR-0907588)

Microtopography is an important factor in hydrologic processes. The purpose of this research was to study the effects of microtopography on runoff generation. Specifically, this was performed through an array of physical experimentation comparing “rough” and “smooth” surfaces under natural and simulated rainfall. Utilizing these types of rainfalls required experimentation to take place in both field and laboratory settings. The range of control factors in this study varied from surface microtopography to soil type, rainfall intensity/pattern, and ambient moisture content. The recorded results of the laboratory study were further compared with the output of a puddle-to-puddle (P2P) overland flow model. The physical experiments showed a trend initially favoring neither the rough nor smooth surface in runoff production. However, in subsequent experiments the rough surface appeared to substantially increase runoff production relative to the smooth surface. Additionally, good agreement was found between the results of the physical experimentation and the model.

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Surfaces cover everything, and since the first standards for the measurement and characterization of surface texture were written researchers, scientists, and engineers have known that all surfaces have a directional property. This property is either an alignment of features or roughness on the surface (anisotropy), a lack of such an alignment (isotropy), or in most cases something in between. In the earliest standards written, this anisotropy of surfaces was characterized visually and referred to as “Lay.” This lay is almost always caused by the process that created the surface of question and can have significant impact on the surfaces performance when interacting with other surfaces in cases where fluids or partials are flowing over the surface. By the late 1900s researchers began to quantify surface anisotropy and by the year 2000 it had been established that surface anisotropy is a multi-scale phenomenon. In this work I look at and expand the state of the art in the characterization of surface anisotropy with examples from both biological and engineering surfaces.

L’ingénierie métabolique est une discipline qui vise à modifier artificiellement le métabolisme d’un organisme afin de lui faire produire un composé chimique d’intérêt. L’une des problématiques fréquemment rencontrées pour la production de nouvelles molécules est l’impossible diffusion du produit formé dans le cytoplasme vers l’extérieur de la cellule. Ce phénomène engendre une accumulation de ce dernier à l’intérieur du micro-organisme qui limite sa capacité de production pour des raisons de cinétiques chimiques et de toxicité pour l’hôte. Enfin, cela complique fortement la récupération et la purification de la molécule d’intérêt, ce qui peut réduire à néant le rendement économique du procédé industriel.Durant cette thèse, nous avons exploré la possibilité de réaliser les dernières étapes de synthèse de composés imperméables pour la membrane à l’extérieur de la cellule en utilisant des enzymes accrochées à la surface de la levure par la technique de “yeast surface display”.Dans une première partie, nous avons regardé l’intérêt industriel de la bioéconomie, puis nous nous sommes intéressés aux problématiques liées à la perméabilité des membranes plasmiques. Dans un second temps, nous avons évalué les méthodes de mesures de la perméabilité des membranes biologiques et exploré la possibilité de développer une méthode prédictive en utilisant une technique de relation structure-propriété. Dans un troisième temps, nous avons évalué les systèmes de “yeast surface display” disponibles et cherché à en découvrir de nouveaux, adaptés à nos problématiques. Dans l'objectif de construire ces bibliothèques nous avons aussi réalisé un outils informatique, permettant de calculer de grands nombres de primers. Enfin, nous avons réalisé différents circuits de production de molécules modèles pour évaluer la pertinence de l’approche pour la production de composés imperméables. / Sustainable chemical production is one of the endeavour of the post-oil era. Amongst the possible techniques, metabolic engineering which aims at producing novel compounds through genetic engineering of micro-organism is seen as one of the most promising techniques. One of the problem met by metabolic engineers is often the absence of diffusion or pumping mechanism expelling the compound of interest produced in the cell cytoplasm towards the outer environment, which reduces the process efficiency because of kinetic and toxicity concerns.During this PhD, we explored the possibility of producing impermeable compounds on the surface of a cell by anchoring the last reaction enzyme using « Yeast surface display » techniques.As PhD disputation we first looked at the industrial interest of metabolic engineering in the whole bioeconomy framework. We then looked at the membrane permeability issues met for the production of some compounds. We evaluated the different membrane permeability techniques and explored the possibility realizing a predictive technique using quantitative structure-property relationship (QSAR). We evaluated the different yeast-display systems available and paved the way for the discovery of new systems more suitable for metabolic engineenering. We developped a dedicated program tool for large PCR fragment library design. Finally we built several toy metabolic pathways in yeast in order to evaluate the interest of the technique.

Indiana University-Purdue University Indianapolis (IUPUI) / A Polyvinylchloride surface was modified by coating a biocompatible, hydrophilic and antibacterial polymer by a mild surface modification method. The surface was first activated and then functionalized, followed by coating with polymer. The surface functionality was evaluated using cell adhesion, bacterial adhesion and bacterial viability for polymers with antibacterial properties. 3T3 mouse fibroblast cells were used for cell adhesion, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus were used for bacterial adhesion in the first study, Pseudomonas aeruginosa and Staphylococcus aureus were used for bacterial adhesion and antibacterial activity in the second study. Chapter 2 reports how we synthesized, immobilized and evaluated a novel hydrophilic polymer with anti-fouling properties onto surface of polyvinylchloride via an effective and mild surface coating technique. The polyvinylchloride surface was first activated by azidation as well as amination, and then tethering a newly synthesized hydrophilic and biocompatible polyvinylpyrrolidone having pendent reactive succinimide functionality onto the surface. Results show that the coated hydrophilic polymer significantly reduced the 3T3 fibroblast cell adhesion as well as the adhesion of the three bacterial species. Chapter 3 reports how we prepared, immobilized and evaluated an antibacterial and anti-fouling polymer onto polyvinylchloride surface following an efficient and simple method of surface modification. The surface coated with a terpolymer constructed with N-vinylpyrrolidone, 3,4-Dichloro-5-hydroxy-2(5H)-furanone derivative and succinimide residue was evaluated with cell adhesion, bacterial adhesion and bacterial viability. Surface adhesion was evaluated with 3T3 mouse fibroblast cells and two bacterial species. Also, antibacterial activity was evaluated by bacterial viability assay with the two bacterial species. Results showed that the polymer-modified polyvinylchloride surface exhibited significantly decreased 3T3 fibroblast cell adhesion and bacterial adhesion. Furthermore, the modified polyvinylchloride surfaces exhibited significant antibacterial functions by inhibiting bacterial growth with bactericidal activity. Altogether, we have successfully modified the surface of polyvinylchloride using a novel efficient and mild surface coating technique. The first hydrophilic polymer-coated polyvinylchloride surface significantly reduced cell adhesion as well as adhesion of three bacterial species. The second hydrophilic and antibacterial polymer-coated polyvinylchloride surface demonstrated significant antibacterial functions by inhibiting bacterial growth and killing bacteria in addition to significantly reduced 3T3 fibroblasts and bacterial adhesions.

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