Yes / This study examines experimentally and for the first time the effect of reduced air pressure on dynamic wetting. The purpose is to assess the role of air viscosity on dynamic wetting failure which hitherto has been speculated on but not measured. In this paper we used dip coating as the model experimental flow and report data on air entrainment velocity Vae we measured with a series of silicone oils in a range of viscosities in a vacuum chamber where the pressure can be reduced from atmospheric down to a few mbar when the mean molecular free path of air is large and air ceases to have a viscosity. To complement earlier work, we carried out the experiments with a range of substrates of varying roughness. The substrates were chosen so that for each one, their two sides differ in roughness. This enables simultaneous comparative observation of their wetting performance and reduces the experimental error in assessing the role of roughness. The data presented here capture the effects of viscosity, roughness and air pressure but the important result of this study is that Vae can be increased considerably (exponentially) when the pressure is reduced with the suggestion that Vae approaches infinity as pressure approaches zero. In other words, the role of the surrounding air viscosity is important in dynamic wetting. The data from this study have significant implication to the fundamental understanding of dynamic wetting. Indeed they form the missing data link to fully understand this phenomenon. The data presented in this work also confirm the complex role of roughness, in that it can increase or decrease the air entrainment speed depending on the value on the viscosity of the coating solution. The results presented in this paper are very useful in practice as they imply that if one chooses carefully roughness one can coat viscous formulation at unexpectedly very high speeds with a moderate vacuum (50 mbar typically).

Yes / The coating flow examined here, labelled angled dip coating, is that where a substrate enters a pool of liquid forming an angle ß with the vertical so that it intersects the liquid along a wetting line which is not perpendicular to the direction of its motion. This flow situation is distinctly different from that where the substrate, inclined in the other dimension by the so-called angle of entry ¿, intersects the liquid surface perpendicularly to its motion. Experiments were carried out with various liquids to determine the effect of ß on the substrate velocity at which air is entrained into the liquid. It was observed that as this angle departs from zero, air entrainment is delayed to higher speeds. The data show that the speed which is relevant to air entrainment is not the velocity of the substrate itself but its component normal to the wetting line. This result has important practical implications and suggests that this fundamental principle is also applicable to other coating flows.

No / This paper presents an integration procedure for the Reynolds-averaged Navier-Stokes equations for the determination of the distribution of the streamwise velocity using the vertical component. This procedure is dedicated to the outer region and central part of channels. The proposed model is applicable to both rough and smooth flow regimes, provided the velocity at the inner-outer boundary has been properly defined. To generate a simplified expansion, a number of hypotheses are proposed, focusing in particular on the analytical modeling of the vertical component by adopting a negligible viscosity. The proposed hypotheses are validated by the experimental data existing in the literature. The proposed simplified expansion is studied through a sensitivity analysis and proved consistent in regards to model experimental data. The proposed model seems capable of demonstrating different kinds of flows, including dip phenomenon flow patterns.

Yes / The Prandtl second kind of secondary current occurs in any narrow channel flow causing velocity dip in the flow velocity distribution by introducing the anisotropic turbulence into the flow. Here, a study was conducted to explain the occurrence of the secondary current in the outer region of flow velocity distribution using a universal expression. Started from the basic Navier-Stokes equation, the velocity profile derivation was accomplished in a universal way for both smooth and rough open channel flows. However, the outcome of the derived theoretical equation shows that the smooth and rough bed flows give different boundary conditions due to the different formation of log law for smooth and rough bed cases in the inner region of velocity distribution. Detailed comparison with a wide range of different measurement results from literatures (from smooth, rough and field measured data) evidences the capability of the proposed law to represent flow under all bed roughness conditions.

The Tissue Engineering Lab at California Polytechnic State University San Luis Obispo focuses on creating tissue-engineered Blood Vessel Mimics (BVMs) designed for the preclinical testing of neurovascular devices. These BVMs are composed of silicone models, representing anatomically accurate neurovasculatures, that are sodded with vascular cell types and then cultivated in bioreactors (which maintain physiologic conditions). These silicone models are currently sourced externally from industry partners, so the primary goal of this thesis was to develop the means and methods for the Tissue Engineering Lab to manufacture silicone models in-house. The first aim of this thesis was to develop and explore injection molding as a possible technique for manufacturing silicone models; this included prototyping various designs of molds, developing a viable workflow for injection molding, then assessing the resulting silicone models through measurement characterization, cytotoxicity screening, and BVM set-ups. The first aim found that injection molding was a viable manufacturing technique for making silicone models. The second aim of this thesis explored an alternative manufacturing method, dip-casting, to produce silicone models. The development of dip-casting was similar to injection molding, where several prototyping stages resulted in a viable workflow for making silicone models; the resulting silicone models were then assessed via measurement characterization and a BVM set-up. The second aim found that, in addition to injection molding, dip-casting was a viable technique for making silicone models, although the overall morphology of the resulting models was less desirable than those made by injection molding. The third and final aim of this thesis compared both manufacturing techniques (i.e., injection molding and dip-casting); this aim established that injection molding was preferable for making simple (less intricate) silicone models, whereas dip-casting was preferable for producing complex (more intricate) silicone models. Although the dip-casting technique requires more development to capture complex shapes and produce models with desirable morphologies, the injection molding protocol was formalized into a prescribed workflow for the Tissue Engineering Lab to reference. Overall, this thesis developed and explored two different manufacturing techniques for making silicone models and found that both were capable of making silicone models that could be used to create tissue-engineered BVMs, with injection molded models being ready to implement as the dip-casting process continues to be refined.

Although the petroleum industry has imaged reflections from the sides of salt domes, steeply dipping structures have not been imaged as reflectors outside of sedimentary basins; to do so requires appropriate data acquisition, prestack depth migration, and an excellent seismic velocity model. Poststack time migrated seismic images, normal moveout velocity analysis, well logs, and other geologic information are used to build the velocity model. In regions of interest outside of sedimentary basins, such as major strike-slip faults, seismic reflectivity is often sparse and little is known of detailed subsurface geology. Alternate methods of velocity model construction must be used. First arrival (refraction and turning ray) traveltime tomography is proposed to construct the preliminary velocity model for steep-dip prestack depth migration in settings with little a priori subsurface information. A densely spaced synthetic seismic data set with long-offset recording, modeled after a real survey across the San Andreas Fault, was constructed using a finite-difference algorithm. First arrival traveltimes were picked from the data and a velocity model was constructed using tomography. The velocity model was used to perform a Kirchhoff prestack depth migration of the synthetic shot gathers. The subsurface structure was sufficiently reconstructed that the velocity model could be refined through migration velocity analysis. A series of tomography tests was used to determine the spatial resolution limits of the velocity model. Isolated erroneous anomalies with sizes near the resolution limits were added to the velocity model derived from tomography and used as input for migration. This pessimistic test provided an adequate image and identifiable arrivals in migrated common image gathers, allowing the velocity model to be improved through migration moveout analysis. Data acquisition requirements for tomography include long recording offsets and times, larger sources, and dense spacings, very similar to the requirements for steep-dip reflection imaging. / Master of Science

L'étude du transport électronique dans des nano-objets métalliques et magnétiques issus de la chimie est un challenge en spintronique. En particulier, le manque de résultats expérimentaux révèle la difficulté à positionner ces nano-objets entre des électrodes de mesures tout en préservant leurs propriétés (magnétisme, intégrité des barrières tunnel organiques...). Ce travail de thèse vise à contourner ces difficultés et à étudier le magnétotransport dans ces systèmes. Pour cela, nous avons conçu et développé à l'intérieur d'une boîte à gants couplée à un bâti de pulvérisation cathodique des systèmes expérimentaux d'assemblages de nano-objets. Nous avons étudié les mécanismes mis en jeu lors de l'assemblage par la technique de dip coating, et réussi à déposer des monocouches de nanoparticules (NPs) de natures différentes (FeCo, Fe, Co) sur des surfaces d'Au, de SiO2 et de résine fine (40 nm). Ces résultats, couplés à une technique de nanoindentation, ont permis de mesurer quelques - voire une- NP(s). Une autre technique, la diélectrophorèse, s'est révélée simple et efficace pour piéger et orienter des nano-objets de taille, de nature, et de forme différentes entre des électrodes. Grâce à cette technique et au dépôt d'une couche protectrice d'alumine, nous avons étudié les propriétés de magnétotransport de plusieurs types de nano-objets sensibles à l'oxydation ou à la vapeur d'eau: NPs de Fe, de Co, FeCo et [Fe(H-trz)2(trz)](BF4)] (composés à transition de spin). Trois jeux de barrières tunnel organiques greffés sur des NPs de fer ont présenté de la magnétorésistance tunnel jusqu'à température ambiante. De plus, des nano-objets de [Fe(H-trz)2(trz)](BF4)] de facteurs de forme variable, ont montré une variation de la conductance liée à la transition de spin. Enfin, nous avons étudié l'influence de la longueur des ligands sur les propriétés de conductions de NPs de Cobalt, qui a validé nos méthodes d'échange de ligands et ont pu être analysées quantitativement. Nos travaux rendent désormais envisageable l'utilisation de NPs issues de la chimie dans différents domaines de la spintronique / The study of charge transport in metallic and magnetic nano-objects chemically synthesized is a challenge in spintronic. Particularly, the lack of experimental results reveals the difficulty in locating such nano-objects in between electrodes while preserving their good properties. This thesis aims to overcome these difficulties in order to study the magnetotransport in such systems. Therefore, we have designed and developed technical processes which induce the self-assembly of the nano-objects inside a glove box-sputtering system. After studying the mechanisms involved in the self-assembly obtained by dip coating, we succeeded to deposit monolayers of nanoparticles (NPs) of different materials (FeCo, Fe, Co) on gold surfaces, SiO2 and thin resin film (40 nm). These results, coupled with a nanoindentation technique allows us to measure a few or a unique NP(s). Another technique, called dielectrophoresis, has been proved to be a simple and versatile way to trap (and align) nano-objects with different (aspect ratio), size, nature, and shape in between the electrodes. Thanks to this technique and the deposit of a protective capping layer of alumina, we studied the magnetotransport properties of a large number of nano-objects sensitive to oxidation or humidity: Fe, Co, FeCo and [Fe(H-trz)2(trz)](BF4)] (spin crossover compounds). Three sets of organic tunnel barriers surrounding different Fe NPs presented tunnel magnetoresistance up to room temperature. Moreover, [Fe(H-trz)2(trz)](BF4)] nano-objects with different aspect ratio, highlighted a change in conductance connected to the spin transition. Finally, we validated our ligands exchange methods by studying the influence of the ligands length on the conduction properties of Co NPs, which have been analyzed quantitatively. Our works demonstrate the possibility to use the chemical NPs in different fields of spintronics

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Das bei der Sanierung von großen segmentalen Knochendefekten bestehende Risiko einer fremdkörperassoziierten Infektion soll durch die Integration eines Wirkstofffreisetzungssystems in ein bestehendes textiles Knochenimplantat gemindert werden. Durch Immobilisierung des Wirkstoffs in eine degradierbare Polymermatrix wird eine zeitlich verzögerte Freisetzung bewirkt. Als Wirkstofffreisetzungssystem wird die Kombination von Polylactid (PLA) bzw. Poly(Lactid-co-Glycolid) (PLGA) als Matrixpolymer mit dem Antibiotikum Gentamicin als Wirkstoff untersucht, welches durch Beschichtung der textilen Scaffolds mittels Dip-Coating eingebracht werden soll. Es stehen die drei Beschichtungsmethoden „Suspension“, „Emulsion“ und „Schichtaufbau“ zur Auswahl, die jeweils über eigene Parameter zur Beeinflussung des Freisetzungsprofils verfügen. Die Methode „Suspension“ und die damit verbundenen Einflussfaktoren Korngröße, Korngrößenverteilung sowie Masseanteil des Antibiotikums und Schichtdicke der aufgetragenen Polymerschicht wurde als die günstigste herausgearbeitet. Im Teil II dieser Arbeit wird diese soweit optimiert, dass nahezu über den gesamten geforderten Zeitraum die festgelegte notwendige Dosierung aufrechterhalten werden kann. Erste in vitro Versuche weisen auf eine gute Zellverträglichkeit sowie eine ausreichende mikrobielle Wirksamkeit hin. / To reduce the risk of infection in the treatment of long bone defects, a novel embroidered bone implant is to be provided with an antibiotic drug delivery system. Prolonged and controlled drug release can be achieved by coating the thread material with antibiotics incorporated in a degradable polymer matrix. The chosen drug delivery system is composed of polylactide acid (PLA) or poly(lactide-co-glycolide) acid (PLGA) as matrix polymer and the antibiotic gentamicin. It is integrated into the textile structure by dip-coating providing the three different methods suspension, emulsion and layered. Each method bears its appropriate parameters to influence the releasing profile. The suspension-method and its parameters grain size and grain size distribution as well as mass fraction of the antibiotic and the coating thickness could be proved as the most feasible. In part II of this essay the chosen coating set-up gets optimized so that a drug release nearly along the whole required term can be achieved. Preliminary in vitro studies show a good cell tolerance besides a sufficient microbial efficacy.