Dissertations / Theses on the topic 'Soft surfaces'
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Chakrabarty, Souvik. "NOVEL SOFT SURFACES WITH INTERESTING SURFACE AND BULK MORPHOLOGY." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/397.
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The goal of this research is to cover a broad set of scientific investigations of elastomeric materials based on polydimethylsiloxane (PDMS) and poly((3,3,3-trifluoroethoxymethyl)methyloxetane) diol. The scope of study covers five areas, well correlated with each other. The first study investigates the near surface morphology of condensation cured PDMS as a function of increasing the amount of siliceous phase. The appearance, disappearance and reappearance of untreated fumed silica nanoparticles at the PDMS near surface and their correlation with the volume fraction of siliceous phase have been studied. This research with PDMS nanocomposites has led to the development of an alternative route for improving mechanical strength of PDMS elastomers, conventionally known to have weak mechanical properties. The second study involves synthesis of a triblock copolymer comprising of four mutually immiscible phases, namely, soft segments comprising of fluorous and silicone domains, a diisocyanate hard segment and a glassy siliceous phase. Structure-property relationship has been established with an investigation of the interesting surface and bulk morphology. The highly improved mechanical strength of these soft materials is noteworthy. The dominance of silicone soft block at the triblock near surface has led to the third study which investigates their potential non-adhesive or abhesive characteristic in both a laboratory scale and in a marine environment. The peak removal stress and the removal energy associated with the detachment of a rigid object from the surface of these triblock copolymers have been measured. Results obtained from laboratory scale experiments have been verified by static immersion tests performed in the marine environment, involving the removal of adhered soft and hard fouling organisms. Gaining insights on the characteristics of an easy release surface, namely low surface energy and a low near surface modulus, a new way for controlling the near surface composition for elastomeric coatings have been developed. This technique involves an elastomer end-capped with a siliceous crosslinking agent and a tough, linear polyurethane. The basic concept behind the hybrid compositions is to develop a coating suitable for foul release applications, having a low energy surface, low surface modulus but good bulk mechanical strength. Henceforth, the fourth study deals with synthesis and characterization of the hybrid polymers over a wide range of composition and investigates their foul release characteristic in laborartory scale experiments. In our final study, attempts have been made in generating a silicone coating with antimicrobial property. A quaternary alkylammonium in different weight percents have been incorporated into a conventional, condensation cured polydimethylsiloxane (PDMS) elastomer. Antimicrobial assay has been performed on these modified silicone coatings to assess their biocidal activity against strains of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Surface accessibility of quaternary charges has been quantified by measuring the streaming potential of a modified coating. An effort has been made in improving the mechanical strength of the weak PDMS elastomers by adding treated fumed silica nanoparticles as reinforcements. The effect of adding fillers on the mechanical property (tensile), surface concentration of quaternary charge and on the biocidal activity of a representative sample has been investigated.
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Kabiri, Farnaz Kabiri. "Gecko Adhesion on Soft Surfaces." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1516061596336554.
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Porter, Matthew Stanton. "Soft x-ray speckle from rough surfaces /." view abstract or download file of text, 2000. http://wwwlib.umi.com/cr/uoregon/fullcit?p9957568.
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Thesis (Ph. D.)--University of Oregon, 2000.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 100-104). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9957568.
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Welsch, Nicole. "Interactions of proteins with soft polymeric surfaces." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16633.
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Im Rahmen der vorliegenden Arbeit wurde die Thermodynamik und Kinetik der Proteinadsorption auf neutralen sowie geladenen, kolloidalen Kern-Schale-Mikrogelen untersucht. Die weiche polymere Schicht der Schale reagiert mit großen Volumenänderungen auf Änderungen der Umgebungstemperatur, des pH-Wertes oder der Salzkonzentration. Untersuchungen mit Fourier-Transform-Infrarotspektroskopie (FT-IR) zeigten, dass generell die native Sekundärstruktur der verwendeten Proteine, die auf den Mikrogelen adsorbiert wurden, erhalten blieb. Im Gegensatz zur Proteinadsorption auf festen Oberflächen wurde zudem eine hohe katalytische Aktivität der Enzyme nach der Immobilisierung verzeichnet, die gegenüber derjenigen der freien Enzyme in manchen Fällen sogar erhöht war. Mithilfe der isothermalen Titrationskalorimetrie (ITC) und FT-IR Spektroskopie wurden als treibende Kräfte des Adsorptionsprozesses elektrostatische und hydrophobe Wechselwirkungen identifiziert. Weitere Untersuchungen zeigten, dass im Falle von geladenen Mikrogelen das elektrostatische Potential wie auch der abgesenkte lokale pH-Wert innerhalb des Netzwerks eine Änderung des Ladungszustands der adsorbierenden Proteine zur Folge hat. Zusätzlich konnte mithilfe der Fluoreszenzspektroskopie und der Verwendung Fluoreszenz-markierter Proteine die kinetische Aufnahme in die Mikrogele als auch die Reversibilität der Reaktion analysiert werden. Es wurde dabei ein dynamischer Austausch zwischen gebundenen und freien Proteinmolekülen nachgewiesen, welcher die Verwendung von Gleichgewichtsmodellen für die Beschreibung der Proteinadsorption rechtfertigt. Außerdem erfolgt der Vorgang in zwei Schritten: i) ein schneller diffusionslimitierter Schritt, in dem der Hauptteil der gesamten Proteinmenge bindet und ii) ein anschließender wesentlich langsamerer Bindungsvorgang. Die Adsorptionsexperimente wurden anschließend auf Untersuchungen in binären Proteinmischungen ausgedehnt, um die kompetitive Proteinadsorption zu studieren.In the present work the thermodynamics and the kinetic mechanism of protein adsorption to charged and uncharged core-shell microgels of colloidal dimension were explored. The soft polymeric layer of the shell is sensitive towards changes of the temperature, pH value, and salt concentration of the solution which results in a drastic volume change upon change of one of these triggers. Studies with Fourier-transform infrared (FT-IR) spectroscopy showed, that the secondary structure of the proteins used was significantly retained after immobilisation regardless of the charge state of the microgels employed. Moreover, unlike protein adsorption onto solid surfaces immobilisation into the networks did not compromise the catalytic activity of the proteins. Actually, an enhanced activity was found for some cases. The thermodynamic analysis performed by isothermal titration calorimetry (ITC) and structural investigations by FT-IR spectroscopy experiments led to the identification of the electrostatic and hydrophobic interactions as the main driving forces of protein adsorption. Further studies showed that proteins bound to negatively charged gel networks regulate their charge according to the electrostatic potential and to the lowered local pH value around the hydrogels. Fluorescence spectroscopy experiments with fluorescent-tagged proteins were suitable to analyse the kinetic uptake of the proteins into the gel networks as well as the reversibility of binding. It was demonstrated that bound proteins are dynamically exchanged by proteins in solution which justifies the application of equilibrium binding models to quantify the adsorption data. Moreover, the adsorption of proteins proceeds in two steps: i) a fast, diffusion-limited binding regime in which the majority of proteins is bound and ii) a second slow binding regime. The adsorption experiments were extended to binary protein mixtures in order to study competitive protein adsorption.
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Shirafkan, Abbas. "Wettability and hydrophilicity of rigid and soft contact lens surfaces." Thesis, City University London, 1997. http://openaccess.city.ac.uk/8385/.
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In the last two decades an abundance of contact lens materials with unknown surface properties have been introduced as well as new contact lens design. Recent studies have identified the importance of physical and chemical interactions between materials and liquids. The purpose of this experimental research work was to investigate the relationship between a contact lens surface and a liquid. The wettability and hydrophilicity of both soft and rigid contact lens surfaces were determined using two novel techniques and an established method. The two novel techniques were the un-separated adherent quid/laser method and the adherent liquid/ maximum force method whereas the established technique involved monitoring the receding wetting angle and interface are a diameter of a sessile drop. Contact lens surface preparation and the method of removing a liquid from hydrated surfaces were found to be important variables when determining wettability or hydrophilicity. Experiments showed that the use of surface tension to remove liquid from hydrated surfaces significantly improved the reproducibility of subsequent measurements. Variation of the sessile drop wetting angle and interface area diameter with evaporation time demonstrated different values for different contact lenses. The clinical consequence of monitoring the receding values would be; if a material to spread tear break up time occurs the dry patches will be advanced on PMMA, rather than Paraperm contact lens. Surface hydrophilicity, if defined in terms of the maximum adherent force, describes the ability of a lens surface to attract a liquid, whereas wettability may be defined as the ability of a liquid to spread on a contact lens surface. The wettability and hydrophilicity, therefore, are two different issues. When a wetting angle is 01, or close to 0" the surface is described as wettable. Results demonstrated that Equalens had a greater surface wettability and hydrophilicity than the PMMA for pre-wear, but the post-wear hydrophilicity for PMMA was greater than Equalens. The use of each measurement method, therefore, resulted in a value that is intrinsically related to measurement method and definition. The clinical consequenceo f the valuesi s to help practitioners prescribea lens material either on wettability or hydrophilicity values. In contact lens practice, a lens surface is required to maintain a stable tear film and produce a long tear film break up time. A combination of hydrophilicty and wetting angle values can help to determine the requirement of wettability and hydrophilicity in the contact lens industry and also in practice. It can be concluded that no single test can fully describe the surface properties of contact lens surface materials, but it is proposed that information and results from a series of tests provides the most useful clinical description.
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Kargar, Mehdi. "Controlling Microbial Adhesion to the Surfaces Using Topographical Cues." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/42771.
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The state of adhesion of bacteria to nanofiber-textured model surfaces is analyzed at single-cell level. The results reveal similarities between the effect of topography on bacteria-surface interactions and vesicle-surface interactions. The results are discussed in the context of controlling bacterial adhesion to surfaces using nanofibrous topographical features.Master of Science
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Lahrashe, Moktar. "Atomic force microscopy of soft surface : Characterisation of holographic optical elements." Université Louis Pasteur (Strasbourg) (1971-2008), 2005. http://www.theses.fr/2005STR13046.
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Les méthodes pour la measurement des surfaces ont progressé d’une façon significative les dernières années. Elles ont été favorisées par les besoins de lithographie avancée. Le but de cette thèse est d’appliquer les techniques récemment développées au problème spécifique de l'étude de la structure de surface des réseaux holographiques. Au début de cette thèse, nous avons fait une recherche bibliographique dans le but de trouver le meilleur dispositif pour notre travail. Le dispositif choisi est un microscope à force atomique (AFM). Ce dernier est un outil permettant une mesure localisée d’une résolution sans précédent. L'AFM fournit une image des structures de surface dans une plage de quelques nanomètres à quelques centaines de micromètres. Cette flexibilité permet de réaliser une analyse quantitative de la microrugosité des surfaces avec de grande sensitivité et précision. Plusieurs exemples de réseaux holographiques enregistrés sur les plaques sont étudiés. Nous avons procédé pour chaque type de plaque à l’analyse du profil du réseau, de sa profondeur, de sa rugosité et la mesuré de le module élastique a été effectue. En outre, le sondage AFM des structures sub-surfaciques a été réalisé pour les échantillons holographiques avec la gélatine comme étant la couche supérieure. Une méthode optique complémentaire nous a servit pour obtenir des informations sur les caractéristiques global des réseaux holographiques : Indice de réfraction, modulation d'indice de réfraction, période du réseau, épaisseur de l'émulsion et absorption et pertes de dispersion ont été mesuréDriven largely by the needs for advanced lithographic processes surface measurement methods have significantly advanced in the last decade. The aim of this thesis is to apply recently developed measuring techniques to the specific problem of investigating the surface structure of holographic recording gratings. At the start of thesis, search for relevant literature was given high priority, with the purpose to find the best measuring device suitable for this investigation. The device chosen was an atomic force microscope (AFM) which is a tool that enables the spatially localised measurements with unprecedented resolution. AFM provides high-resolution imaging of surface structures from few nanometres to hundreds of micrometres. This capability is useful for quantitative analysis of surface micro-roughness of technological surfaces with high sensitivity and accuracy. Various holographic gratings are studied, along with the sequence by which raw images are analysed for grating profile, profile consistency, grating depth, profile roughness and elastic modulus. In addition, AFM probing of subsurface structures has been achieved for holographic samples with gelatine - like top layers. The AFM characterisation is completed with optical characterisation of holographic gratings: i. E. The refractive index, the refractive index modulation, the groove period, the emulsion thickness and the absorption and the scattering losses are determined by this method
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Yarlagadda, Sri Charan. "Dynamics of hard and soft colloids in confined geometries and on structured surfaces." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53888.
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We investigated the depletion interactions of colloids and hindrance behavior of hard and soft colloidal particles near neighboring walls. We first used numerical modeling to compute depletion interaction strengths for simple geometries which eventually guided our experiments to make interactions highly selective. The model helped us in identifying the important parameters to finetune these interactions and shed light on geometric design rules to optimize desirable shape-selective interactions on a variety of complex geometries. We further reported experimental studies that highlight the differences in the dynamics of hard and soft colloids under confinement using video microscopy and particle tracking. It was found that both soft sphere systems that we investigated (swollen polymer particles, core/shell microgels) behave differently from hard sphere systems under all degrees of confinement that were measured. Our findings suggest that soft sphere systems have lesser hindrance compared to hard sphere counterparts and the hindrance varies as a function of softness. In order to understand the soft sphere confinement dynamics more clearly, implications for future research are discussed.
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Volný, Michael. "Reactive and soft landing of polyatomic gas-phase ions on plasma-treated metal surfaces /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8650.
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Koller, Anton W. "The friction coefficient of soft contact lens surfaces in relation to comfort and performance." Thesis, City University London, 2014. http://openaccess.city.ac.uk/13791/.
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The soft contact lenses of today are made from a variety of hydrogel materials. These materials have different properties in terms of water content, monomers, hardness and other tensile characteristics. It is likely that the frictional properties also vary between materials. It is known that constituents of the tear film interact with contact lens materials to form a biofilm on the lens surface. The hypothesis of this research is that although the frictional properties of lens materials may vary these properties do not affect the comfort and performance of the lenses in vivo. A tribometer is a device to measure the coefficient of friction of materials. There was no commercially available tribometer designed specifically for use with contact lens materials, so one was constructed and validated against standard solid materials. The same equipment was used to determine the friction coefficients of five contemporary soft lens materials under different conditions of lubrication but, unlike other tribometers, this unique design simulated human blinking as far as possible. The experimental friction coefficients varied widely from 0.27 to 5.89 under different conditions of lubrication. The largest variation between materials was seen using the most viscous lubricant. For the in vivo studies the author coordinated the manufacture of 250 contact lenses, which were lathe cut and polished to a standard design, achieving exceptionally tight tolerances, using the same five materials. This rigourous process was carried out to minimise variations in the geometry of each contact lens. Subjects were screened to minimise ocular heterogeneities between subjects. Clinical performance of each lens was assessed using comfort, contrast sensitivity, visual acuity, entoptic phenomena, non-invasive tear break-up time and lens movement on the eye. In a clinical environment none of these parameters showed any associations with the coefficients of friction found in vitro, apart from a moderate correlation (rho = 0.5) between lens movement and the coefficient of friction under borderline friction conditions. In conclusion, the findings of this research support the hypothesis that frictional properties of soft lenses do not affect comfort and performance in vivo.
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Supreeti, Shraddha [Verfasser], Stefan [Akademischer Betreuer] Sinzinger, Martin [Akademischer Betreuer] Hoffmann, and Steffen [Akademischer Betreuer] Strehle. "Soft nanoimprint lithography on curved surfaces / Shraddha Supreeti ; Stefan Sinzinger, Martin Hoffmann, Steffen Strehle." Ilmenau : TU Ilmenau, 2021. http://d-nb.info/1239051182/34.
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Liu, Zhiqiang. "Modelling and experimental studies of contact and friction of metallic rough surfaces in initial sliding." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/542.
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Chen, S. "An experimental investigation of drop impact phenomena with complex fluids on heated and soft surfaces." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3011893/.
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The present thesis is the result of a four year experimental research, which aims at studying the impact of non-Newtonian droplets (i.e., droplets of complex fluids such as polymer solutions) on heated surfaces (i.e., surfaces with a temperature above the Leidenfrost point) and soft surfaces (i.e., surfaces that undergo temporary or permanent deformations upon drop impact) through high-speed imaging. In the first year we focused on the Leidenfrost drop impact of different model fluids with matching flow curves. We demonstrate that the total kinetic energy carried by low-viscosity Newtonian drops during retraction is partly transformed into rotational kinetic energy rather than dissipated (published on Physical Review E, 2016). In the second year we extended the Leidenfrost drop impact experiment to viscoplastic fluids. The results show that the main contribution to drop rebound is due to surface forces rather than the elasticity of vapour cushion (published on Soft Matter, 2016). A systematic investigation on the impact of viscoplastic drops onto viscoplastic substrates was carried out in the third year. It is shown that the yield stress magnitude of drop/substrate strongly affects the final shape of the impacting drop (published on Soft Matter, 2017). The fourth year was devoted to the drop impact on spherical elastic surfaces. The dynamic contact angle measured using a novel digital image processing scheme is found to be significantly affected by the impact parameters and a quantitative estimation of the deformation energy is proposed (published on Physics of Fluids, 2017).
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Li, Wanbo. "Rapid and low-cost mass fabrication of true three-dimensional hierarchical structures with dynamic soft molding and its application in affordable and scalable production of robust and durable whole-teflon superhydrophobic coating." HKBU Institutional Repository, 2019. https://repository.hkbu.edu.hk/etd_oa/611.
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Superhydrophobic (SH) surfaces equipped on the skins of natural living beings give them trumps of self-cleaning, anti-bacterial, water harvest, and directional liquid transport, etc., to survive in harsh environments. Bioinspired Superhydrophobic (SH) surfaces have developed many emerging functions, such as self-cleaning, anti-bacterial, water harvest, anti-icing, anti-corrosion, oil-water separation, and many other fascinating functions. However, the implementations of SH coating in real world are still in its infancy, due to (i) the poor performance in the harsh real-world environment and industrial process application, where a multi-level robustness including the mechanical, chemical, and thermal robustness, as well as the strong adherent strength to substrates, is strictly required; (ii) the lack of a technology for facile and mass production. In the light of that any non-perfluorinated component in the formula of an SH coating inevitably generates vulnerable points to the external invasions and the functional applications of SH coatings require control surface topography, we here propose an SH coating entirely made of perfluorinated materials (referred to as Teflon). To achieve this goal, we developed a complete strategy involving material, fabrication, and applications. Firstly, we developed a feasible dynamic soft molding method for the fabrication of three-dimensional (3D) structures. This method paves a road not only to the fabrication of whole-Teflon SH coatings but also to the practical adoption of many other important technologies based on 3D structures. Secondly, we generated whole-Teflon and multi-resist SH coatings by using this method and tightly attached them to different substrates with superior adhering strength surpassing the conventional work. Thirdly, we performed a proof-of-concept demonstration of a roll-to-roll (R2R) hot molding process, which has the potential of translating the lab-scale and plate-to-plate fabrication to industrial mass production. Finally, some fundamental mechanisms and problems of the multifunctional applications in self-cleaning, anti-bacterial fouling, and anti-icing are studied. The outcomes are expected to provide insight understandings on the multifunctional SH coating and move SH coatings toward real-world application.
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Wedler, Nils David [Verfasser], and C. [Akademischer Betreuer] Barner-Kowollik. "Dynamic Bonding in Soft Matter Materials and on Surfaces / Nils David Wedler ; Betreuer: C. Barner-Kowollik." Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/1126036900/34.
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Song, Sukho. "Soft Robotic Grippers Using Gecko-Inspired Fibrillar Adhesives for Three-Dimensional Surface Grasping." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/936.
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Researches on biological adhesive systems in nature have changed a perspective view on adhesion that it is not only the area of surface chemistry, but also mechanics of interfacial geometry which can significantly effect on fracture strength and load distribution on the contact interface. Various synthetic fibrillar adhesives in previous works have shown enhanced interfacial bond strength with the capacity of adhesion control by exploiting mechanical deformation of the elastomeric fibrillar structures inspired by geckos. However, control of the interfacial load distribution has been focused on the size of micro-contact with single or a few of micro-/nano-fibers on planar surface, and not for a large contact area on complex three-dimensional (3D) surfaces. This thesis work aims at investigating principles of the interfacial load distribution control in multi-scale, ranging from micro-contact with single micro-fiber to a centimeter-scale contact with a membrane-backed micro-fiber array on non-planar 3D surfaces. The findings are also applied for developing a soft robotic gripper capable of grasping a wide range of complex objects in size, shape, and number, expanding the area of practical applications for bio-inspired adhesives in transfer printing, robotic manipulators, and mobile robots. This paper comprises three main works. First, we investigate the effect of tip-shapes on the interfacial load sharing of mushroom-shaped micro-fibrillar adhesives with precisely defined tipgeometries using high resolution 3D nano-fabrication technique. For a large area of non-planar contact interface, we fabricate fibrillar adhesives on a membrane (FAM) by integrating micro-fibers with a soft backing, which enables robust and controllable adhesion on 3D surfaces. Picking and releasing mechanism for the maximal controllability in adhesion are discussed. Finally, we propose a soft robotic architecture which can control the interfacial load distribution for the FAM on 3D surfaces, solving an inherit dilemma between conformability and high fracture strength with the equal load sharing on complex non-planar 3D surfaces.
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Welsch, Nicole [Verfasser], Matthias [Akademischer Betreuer] Ballauff, and Nikolaus P. [Akademischer Betreuer] Ernsting. "Interactions of proteins with soft polymeric surfaces : driving forces and kinetics / Nicole Welsch. Gutachter: Matthias Ballauff ; Nikolaus P. Ernsting." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://d-nb.info/1029141150/34.
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Sabiri, Noura. "Caractérisation du toucher des surfaces polymères, essais de corrélation entre analyse sensorielle : Mise au point d'un matériau à toucher "soft"." Paris, CNAM, 2008. http://www.theses.fr/2008CNAM0624.
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In consideration of various current criteria such as durability and comfort, always taken into account during the purchase of a vehicle, nowadays nex criteria called sensory feelings such as smell and touch occupie a growing position. The present study deals with the evaluation of touch and more particulary touch of plastics, widely used in car cockpits. According to more recent technology researchs, only sensory analysis allows a good caracterization of touch , but this analysis is particulary difficult to implement. That's why we try to confort results by valuing touch with convenient physical measurements such as rubbibg and roughness tests. The first part of this work consists in proving tat the reliability of the sensory analysis results from definite criteria (repeatibility, consistency, precision of analysis). Then, we determine the rubbing coefficient and evaluate the roughness of surface of various samples. This study encloses a statistical field in order to try and present the reliability measurement processes. Then, we try to establish a relationship between the results obtained firstly with sensory analysis such as "Slippery" "Rough" descriptors and secondly with instrumental measurements. In the second part, we study the imrovement of the touch of propylene formulations used in car cockpits. In this way, we try to obtain directly a surface material, without coatin, able to replace components coated with "soft" touch paint or zequivalent. We also verify that the mechanical properties required for applications are in good accordance witth waited valuesAux différents cirtères tels que durabilité et confort, toujours pris en compte pour l'achat d'un véhicule, viennent maintenant s'ajouter des critères dedimensions sensorielles comme l'odorat et le toucher. C'est sur l'évlauation de ce dernier cirtère qu'a porté notre étude. Les matières plastiques étant largement utilisées dans l'habitacle automomobile, c'est à leur toucher quue nous nous intéressons particulièrement. Actuellement, seule l'analyse sensorielle permet de carctériser le toucher, mais cette analyse est particulièrement difficile à mettre en oeuvre. C'est pourquoi, nous essayons d'évaluer le toucher à l'aide de mesures physiques adaptées telles que des essais de frottement et de rugosité. La première partie de ce travail consiste tout d'abord à s'assurer de la fiabilité des résultats de l'analyse sensorielle en se basabt sur des critères précis (répétabilité, cohérence, finesse d'analyse), Nous déterminons ensuite le coefficient de frottement et la rugisité de surface d'échantillons variés. Cette étude est précédée par une démarche statistique ayant pour but d'étudier la fiabilité de processus de mesure. Puis, nous essayons d'établir une corrélation entre les résultats de l'analyse sensorielle pour les descripteurs "Glissant" et "Râpeux" et les résultats de mesures physiques associées. Dans la deuxième partie, nous présentons une étude sur l'amélioration du toucher des matériaux à bas de polypropylène utilisés dabs les piéces d'intérieur automobile. L'objectif est ici d'obtenir un matériau à toucher "soft" pour remplacer des pièces revêtues de peinture "soft", tout en gardant les propriétés mécaniques exigées par le cahier des charges
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Rios, Neyra César. "Design of mechanoresponsive surfaces and materials." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAE019/document.
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Le but de ma thèse a été de concevoir des matériaux chimio-mécano répondants, des matériaux capables de permettre une transformation chimique réversible lorsqu’ils sont soumis à un stress mécanique. Tous les systèmes conçus ont été développés sur des substrats en silicone. Une première approche a consisté à créer des surfaces à sites cryptiques où une biotine est enfouie dans des brosses de chaines de poly(éthylène glycol). Le système streptavidine/biotine a été utilisé comme modèle. Ces surfaces sont anti-adsorbantes à la streptavidine sauf lorsqu’elles sont étirées à 50% où la biotine est reconnue mais les surfaces sont non réversibles. Dans une seconde approche, nous avons modifiés la surface du silicone par adsorption d’une multicouche de polyélectrolytes. Cette stratégie est basée sur la réticulation covalente du film par l’enzyme β-galactosidase modifiée. Nous sommes ainsi parvenus à créer une surface présentant une activité catalytique modulable par l’étirement mécanique, et ce, d’une façon partiellement réversible. Ce travail représente le premier exemple d’un système où une contrainte mécanique imposée à un matériau permet la déformation conformationnelle d’une enzyme et ainsi la diminution de l’activité catalytique. Dans une dernière approche, nous avons conçu un système mixte composé d’un substrat de silicone sur lequel un gel de polyacrylamide est greffée de façon covalente. Des enzymes ou des mécanophores pourront ainsi être inclus dans le réseau polymérique du gel de polyacrylamide et être étirés. Nous sommes parvenus à préparer de tels systèmes où l’hydrogel reste solidaire du film de silicone, sans apparition de craquelures jusqu’à 50%d’étirementThe goal of my PhD was to develop new routes to design chemo-mechanoresponsive materials, materials that respond chemically to a mechanical stress, in a reversible way. All the systems designed during my PhD thesis were based on the functionalization of silicone sheets. First we created cryptic site surfaces by embedding biotin ligands into PEG brushes. The couple streptavidin/biotin was used as a model system. At rest, the surface so-prepared was antifouling and biotin ligands were specifically recognized by the streptavidin when the surface was stretched at 50%. Unfortunately, in this first approach, the mechanosensitive surface did not lead to a reversible process. In a second approach, we modified the silicone surface by using the polyelectrolyte multilayer (PEM) film deposition. This strategy was based on the covalent cross-linking of modified enzyme, the β-galactosidase, into the PEM. We succeeded in modulating the enzyme activity in the film under stretching and this approach appears as partially reversible under stretching/unstretching cycles. This work represents the first reported system where enzymatic activity can be modulated by stretching due to modulation of the enzyme conformation. In a last approach, we also designed a mixed system consisting of a silicone sheet onto which a polyacrylamide hydrogel is covalentlyattached with the goal to create a stretchable gel into which one can covalently attach enzymes or chemical mechanophores. These enzymes or mechanophores can thus be put under mechanical stress. We succeeded in creating a system that can be stretched up to 50% without detachment of the gel from the silicone and without inducing cracks in the gel
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Dupont, Samuel James. "Shape-Shifting Surfaces for Rapid Release and Direct Stamping of Organized Micro-Tissues." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4310.
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The primary aim of the research in this study is to develop a robust and simple platform for the in vitro organization of cells on surfaces which facilitate rapid cell release and allows for the direct stamping of highly organized micro-tissues. Current approaches towards this goal have been very successful but are lengthy and subject cells to harsh conditions for extended periods of time raising questions regarding cell health and maintenance of physiological state. To address these concerns a platform was developed to allow for rapid cell release by utilizing a release mechanism different from previous work.
Micron-scale structures comprised of the thermally responsive polymer poly(N-isopropylacrylamide) (pNIPAAm) were fabricated into various geometries to serve as a platform for cell culture. Structures were covalently confined to rigid surfaces causing non-uniform distortion of the structure's geometry upon swelling. This resulted in four primary modes of geometric distortion, or swelling-induced instability: differential lateral swelling, localized edge buckling, bulk structural buckling, and surface wrinkling. It was found that slight modifications to a linear elastic model was sufficient to predict these behaviors and provided guidance on design of the cell culture platform. Observations also suggest that a rapidly swelling structure engenders multiple forms of instability which arise as sequential and discrete steps during the swelling process. At each step the length scale of the instability increases in a step-wise fashion until the final equilibrium structure is reached.
Culture of NIH 3T3 fibroblasts atop pNIPAAm structures of various geometries resulted in the growth of highly aligned micro-tissue building blocks with three distinct geometries: planar aligned micro-tissue sheets, "ribbon-like" micro-tissues, and "fiber-like" micro-tissues. Release of the micro-tissues was facilitated by the thermally-induced shape-shifting nature of micron-scale pNIPAAm structures. Release occurred rapidly (∼3 min) and required a more mild temperature shift (delta T = 9°C) than other approaches. It was found that the mechanism for cell detachment was mechanical in nature and did not require cellular activity unlike other approaches. Cell detachment was directly correlated to surface strain as a result of thermally-induced shape-shifting and has a level of dependence on cellular contractility.
The platform was tested to show its capacity to directly translocate organized micro-tissues to a virgin surface. Cell transfer by direct stamping was achieved with micro-tissues retaining their shape, although stamped micro-tissues lost their organization after several hours of culture. Although the stamping process requires additional optimization, these results provide evidence that this platform has the capacity to culture and directly translocate highly organized micro-tissues. Additionally, this process provides a new, minimally invasive, approach to cell culture such that rapid construction of highly organized multi-layered tissues can be realized.
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Streubel, Robert. "Imaging Spin Textures on Curved Magnetic Surfaces." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-178266.
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Gegenwärtige Bestrebungen materialwissenschaftlicher Forschung beschäftigen sich unter anderem mit der Überführung zweidimensionaler Elemente elektronischer, optischer, plasmonischer oder magnetischer Funktionalität in den dreidimensionalen (3D) Raum. Dieser Ansatz vermag mittels Krümmung und struktureller Topologie bereits vorhandene Eigenschaften abzuändern beziehungsweise neue Funktionalitäten bereitzustellen. Vor allem Vektoreigenschaften wie die Magnetisierung kondensierter Materie lassen sich aufgrund der Brechung der Inversionssymmetrie in gekrümmten Flächen stark beeinflussen. Neben der Entwicklung diverser Vorgänge zur Herstellung 3D magnetischer Gegenstände sind geeignete Untersuchungsmethoden wie beispielsweise tomografische Abbildungen der Magnetisierung von Nöten, die maßgeblich die physikalischen Eigenschaften bestimmen. Die vorliegende Dissertationsschrift befasst sich mit der Abbildung von magnetischen Domänen in 3D gekrümmten Dünnschichten beruhend auf dem Effekt des zirkularen magnetischen Röntgendichroismus (XMCD). Die in diesem Zusammenhang entwickelte magnetische Röntgentomografie (MXT) basierend auf weicher Röntgenmikroskopie stellt eine zu Elektronenholografie und Neutronentomografie komplementäre Methodik dar, welche großes Anwendungspotential in der elementspezifischen Untersuchung magnetischer gekrümmter Flächen mit örtlicher Auflösung im Nanometerbereich aufweist. Die Schwierigkeit der Interpretation von Abbildungen magnetischer Strukturen in gekrümmten Flächen rührt von der Dreidimensionalität und der Vektoreigenschaft der Magnetisierung her. Die hierzu notwendigen Kenntnisse sind anhand von zwei topologisch verschiedenen Flächen in Form hemisphärischer Kappen und hohler Zylinder erschlossen worden. Die praktische Anwendung von MXT ist abschließend anhand der Rekonstruktion magnetischer Domänen in aufgerollten Dünnschichten mit zylindrischer Form verdeutlichtOne of the foci of modern materials sciences is set on expanding conventional two-dimensional electronic, photonic, plasmonic and magnetic devices into the third dimension. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and three-dimensional (3D) shape. The degree of effect is particularly high for vector properties like the magnetization due to an emergent inversion symmetry breaking. Aside from capabilities to design and synthesize 3D magnetic architectures, proper characterization methods, such as magnetic tomographic imaging techniques, need to be developed to obtain a thorough understanding of the system’s response under external stimuli. The main objective of this thesis is to develop a visualization technique that provides nanometer spatial resolution to image the peculiarities of the magnetic domain patterns on extended 3D curved surfaces. The proposed and realized concept of magnetic soft X-ray tomography (MXT), based on the X-ray magnetic circular dichroism (XMCD) effect with soft X-ray microscopies, has the potential to become a powerful tool to investigate element specifically an entirely new class of 3D magnetic objects with virtually any shape and magnetization. Imaging curved surfaces meets the challenge of three-dimensionality and requires a profound understanding of the recorded XMCD contrast. These experiences are gained by visualizing magnetic domain patterns on two distinct 3D curved surfaces, namely magnetic cap structures and rolled-up magnetic nanomembranes with cylindrical shape. The capability of MXT is demonstrated by reconstructing the magnetic domain patterns on 3D curved surfaces resembling hollow cylindrical objects
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Katakam, Shravana K. "Laser Surface Treatment of Amorphous Metals." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc500194/.
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Amorphous materials are used as soft magnetic materials and also as surface coatings to improve the surface properties. Furthermore, the nanocrystalline materials derived from their amorphous precursors show superior soft magnetic properties than amorphous counter parts for transformer core applications. In the present work, laser based processing of amorphous materials will be presented. Conventionally, the nanocrystalline materials are synthesized by furnace heat treatment of amorphous precursors. Fe-based amorphous/nanocrystalline materials due to their low cost and superior magnetic properties are the most widely used soft magnetic materials. However, achieving nanocrystalline microstructure in Fe-Si-B ternary system becomes very difficult owing its rapid growth rate at higher temperatures and sluggish diffusion at low temperature annealing. Hence, nanocrystallization in this system is achieved by using alloying additions (Cu and Nb) in the ternary Fe-Si-B system. Thus, increasing the cost and also resulting in reduction of saturation magnetization. laser processing technique is used to achieve extremely fine nanocrystalline microstructure in Fe-Si-B amorphous precursor. Microstructure-magnetic Property-laser processing co-relationship has been established for Fe-Si-B ternary system using analytical techniques. Laser processing improved the magnetic properties with significant increase in saturation magnetization and near zero coercivity values. Amorphous materials exhibit excellent corrosion resistance by virtue of their atomic structure. Fe-based amorphous materials are economical and due to their ease of processing are of potential interest to synthesize as coatings materials for wear and corrosion resistance applications. Fe-Cr-Mo-Y-C-B amorphous system was used to develop thick coatings on 4130 Steel substrate and the corrosion resistance of the amorphous coatings was improved. It is also shown that the mode of corrosion depends on the laser processing conditions. The microstructure evolution and the corrosion mechanisms operating are evaluated using post processing and post corrosion analysis.
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Benkoula, Safia. "Étude de la structure, des propriétés de surface et de la réactivité de nanoparticules isolées par spectroscopie de photoélectrons par rayonnement synchrotron dans le domaine des rayons X-mous." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS219/document.
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Au point de convergence entre les sciences fondamentales et les sciences appliquées, les nanosystèmes connaissent depuis une dizaine d'années un développement industriel à l'échelle planétaire. Parmi ces nanosystèmes, les agrégats, petites particules constituées de quelques atomes (ou molécules) à plusieurs milliers d'unités, constituent véritablement "le chaînon manquant" entre l'atome isolé et le solide massif. L'étude des interactions dans les agrégats permettrait de comprendre comment l'atome est influencé par son environnement lorsqu'il est inclus dans un système dense au sein d'autres atomes. La nanoparticule (NP) est constituée de plusieurs milliers à millions d'atomes, ses dimensions étant exprimées en nanomètres (nm, 1 nm = 10^{-9} m).L'engouement que suscitent les agrégats et les NPs est lié à leurs propriétés physiques particulières mais également à leur grande surface spécifique (rapport surface/volume). Il en résulte une grande réactivité liée à des sites réactionnels plus nombreux. Cette caractéristique est exploitée dans de très nombreux domaines d'applications (catalyse hétérogène, dépollution, photovoltaïque, nanomédecine).Cette expansion des activités "nanotechnologiques" implique le développement de méthodes de caractérisation de ces nouveaux types de matériaux, qui sont bel et bien présents dans notre vie.Parmi les méthodes de caractérisation de la matière, la spectroscopie de photoélectrons (XPS) générés par rayonnement synchrotron a, depuis longtemps, prouvé son efficacité pour l'étude des atomes, molécules et des matériaux, et s'est imposée en tant que technique de choix en science des surfaces. L'idée de ces travaux de thèse est de combiner la sélectivité atomique de la spectroscopie appliquée à la matière diluée, avec la sensibilité de surface de la spectroscopie X-mous sur les matériaux pour étudier des nanosystèmes (agrégats et NPs) en phase gazeuse par XPS dans le domaine d'énergie allant de 100 eV à 1000 eV.Nous présentons dans cette thèse les premiers résultats obtenus par cette approche sur la ligne de lumière PLEIADES du synchrotron SOLEIL, ligne à ultra-haute résolution dédiée à l'étude de la matière diluée. Les expériences ont porté sur des matériaux très utilisés dans les secteurs industriel et biomédical, en l'occurrence les NPs de TiO2, de Silicium et les NPs de polystyrène fonctionnalisées par des dérivés glucidiques}. Nous montrons comment l'XPS de NPs isolées nous permet de répondre à des questionnements concrets, comme la réactivité de surface des NPs, les processus et les dynamiques d'oxydation, l'inclusion d'hétéroatomes ainsi que l'interface ligand/NP. Les résultats présentés ici montrent non seulement la faisabilité de la méthode, mais plus encore, prouvent qu'il est possible d'adresser des problématiques appliquées ayant trait à des phénomènes réactionnels surfaciques, sur des NPs isolées, aléatoirement orientéesDuring the past decade, a world-wide industrial expansion of nanosystems has been taking place at the junction between fundamental and applied sciences. Among these nanosystems, clusters, defined as small particles whose constitution ranges from few atoms (or molecules) to several thousand units, constitute "the missing link" between the isolated atom and the bulk solid. Studying the interactions in the aggregates would allow to understand how the atom is influenced by its neighborhood when it is included in a dense system within other atoms. "Nanoparticle" (NP) is usually defined as a system extanding from several thousands to millions of atoms, and its size is expressed in nanometer (nm, 1 nm = 10^{-9} m).This interest for nanosystems mainly results from their particular physical properties at the nanometer scale, but also from their large "surface to bulk" ratio. Hence, more active sites are available at the surface, enhancing their reactivity. This characteristic is used in numerous fields of applications (heterogeneous catalysis, cleanup, photovoltaics, nanomedicine).% and is also relevant in natural processes (atmospheric sprays, volcanic eruptions).This expansion of the "nanotechnological" activities involves the development of new methods for the characterization of these new kinds of materials, which take a considerable part in our daily life. Among the methods of matter characterization, synchrotron radiation based soft X-ray spectroscopy has shown to be a powerful technique for the study of atoms and molecules as well as materials, and appears today as an efficient technique of characterization in surface science.The idea of this thesis is to combine the atomic selectivity of the spectroscopy applied to dilute matter, with the surface sensitivity of soft X-ray spectroscopy, to study isolated nanosystems (clusters and NPs) in the gas phase, by XPS in the energy range of soft X-ray (typically 100 eV to 1000 eV). We present in this thesis the first results obtained by this approach at the PLEIADES beamline of SOLEIL synchrotron radiation facility. PLEIADES is a ultra-high resolution beamline dedicated to the study of dilute matter. The experiments carried out in this work relate to materials often used in the industrial and biomedical fields: TiO2 NPs, Silicon and glycosylated polystyrene NPs. We show how XPS on isolated NPs allows us to answer concrete questions, as the surface reactivity of the NPs, processes and oxidation dynamics, the doping efficiency or the interface ligand/NP. The results presented here not only show the feasibility of the method, but much more than that, prove that it is possible to give insight about surface chemical processes occuring on isolated, randomly oriented NPs
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Zaafouri, Zaineb. "Modélisation de l'adsorption et du transport des surfactants en milieu poreux : influence de la thermodynamique et de la cinétique de l'adsorption." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALY041.
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L'adsorption des tensioactifs se caractérise par un comportement complexe lié aux interactions latérales et à la formation des agrégats de surface. Dans cette thèse, un nouveau modèle est proposé ; celui-ci utilise des rapports d'adsorption-désorption dépendants de la concentration permettant de considérer l'adsorption entravée ou facilitée et intègre un paramètre de tassement servant à caractériser les objets agrégés. Ce modèle a été validé par rapport à des données expérimentales et a démontré son intérêt physique en obéissant à l'approximation quasi-chimique. L'étude numérique de l'interaction entre l'adsorption et le transport est d'un intérêt important pour l'industrie. Dans ce travail, nous effectuons une série de simulations numériques en utilisant le schéma LBM-TRT pour modéliser le transport de traceur passif et adsorbant dans une structure simple et complexe. Les résultats de la modélisation en géométrie de plaques parallèles ont montré que l'adsorption de Henry entraîne un déplacement plus important; et conduit à une sur-adsorption lorsque le rapport adsorption-désorption est élevé. Alors que pour le modèle de Langmuir, les résultats ont montré l'importance de la valeur de la concentration initiale. Une forte valeur conduit à changer les régimes de transport, en introduisant un régime de dispersion de Taylor intermédiaire, avant d'atteindre le régime de dispersion lié à l'adsorption. Par ailleurs, les résultats obtenus dans la géométrie poreuse ont montré que le transport dans cette géométrie est fortement affecté par l'hétérogénéité de la structure ; elle met en évidence un régime de dispersion non stationnaire. De plus, l'adsorption entraîne une diminution de la variance de déplacement en raison de l'adsorption dans la direction x. Grâce à la saturation de surface, le modèle d'adsorption de Langmuir donne plus de molécules dispersées que le modèle d'adsorption de HenryThe adsorption of surfactant exhibits complex behavior related to lateral interaction and the formation of aggregates on the adsorbing surfaces. In this thesis, we propose a new model by using adsorption desorption ratio that are concentration dependent to account for the hindered or facilitated adsorption and a packing parameter to characterize the aggregated objects. The model was validated against experimental data and it proved its physical interest by obeying the quasi-chemical approximation. The numerical study of the interplay between adsorption and transport is of important interest for the industry. In this work, we perform a series of numerical simulation using LBM-TRT scheme to model the transport of passive and adsorbing tracer in simple and complex structure. The results in the parallel plates geometry proved that the Henry adsorption leads to a higher displacement and it leads to an over-adsorption when using high value of adsorption desorption ratio. While for the Langmuir model, results showed the importance of the value of the initial concentration. A high concentration values leads to change the transport regimes, by introducing an intermediate Taylor dispersion regime, before reaching the adsorption dispersion regime. The results in the porous geometry proved that transport in this geometry is highly affected by the heterogeneity of the structure; it showcases a non-stationary dispersive regime. As for the adsorption, it leads to a decrease in the displacement variance since it is hindered by the adsorption in the x-direction. Thanks to the surface saturation, the Langmuir adsorbing model, gives more dispersed molecules than the Henry adsorbing model within the geometry
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Manuzon, Michele Yabes. "Investigation of Pseudomonas Biofilm Development and Removal on Dairy Processing Equipment Surfaces Using Fourier Transform Infrared (FT-IR) Spectroscopy." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253576498.
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Bodin, Audrey. "Un dispositif de filtre en énergie couplé à un spectromètre de masse quadrupolaire pour le dépôt d'ions moléculaires sur des surfaces isolantes avec énergie contrôlée." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2224/.
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L'électronique moléculaire constitue une alternative technologique pour la nanoélectronique. Ce domaine nécessite l'invention de nouveaux équipements afin de pouvoir déposer de grosses molécules fragiles sur des surfaces isolantes sous ultra haut vide (UHV). Conserver intacte la structure spécifique de la molécule après adsorption est primordial pour les fonctionnalités du dispositif envisagé. La technique de dépôt généralement utilisée pour déposer des atomes et molécules neutres sous UHV est l'évaporation thermique. Cette technique est cependant trop énergétique pour déposer des molécules fragiles. Il est donc nécessaire de concevoir des procédés de dépôt moins destructifs utilisant un spectromètre de masse. L'appareil commercial utilisé pour notre étude est un spectromètre de masse Finnigan triple quadrupôle TSQ700, couplé à un équipement multi-chambres, sous UHV, appelé " Dinamo " UHV Factory. Afin de transformer le TSQ700 en source d'ions de basse énergie, nous avons étudié la distribution en énergie des ions, avec le logiciel SIMION(r). Cette étude a révélé que le faisceau d'ions présentait une trainée à haute énergie pouvant aller jusqu'à 1500 eV. Pour trier en énergie le faisceau d'ions, nous avons choisi d'ajouter un secteur électrostatique. Une mesure du courant d'ions en sortie du secteur électrostatique montre que la trainée haute énergie a bien été supprimée. Le spectromètre modifié a été utilisé pour déposer des ions CF3+ sur une surface de KBr (001) caractérisée par la suite par microscopie à force atomique en mode non contact (NC-AFM) et par microscopie à sonde de Kelvin (KPFM). Les observations KPFM confirme la présence de charges positives en surfaceMolecular electronics is an alternative technology for nanoelectronics. It requires the conception of new equipments in order to deposit large and fragile molecules on insulating surfaces under ultra high vacuum (UHV). Keeping intact the deposited molecules is essential for the functionality of the fabricated devices. The most generally used deposition technique for molecules under UHV is thermal evaporation. However, this technique is often detrimental for fragile molecules. The development of less destructive deposition methods is therefore needed. An alternative technique is based on the use of a dedicated mass spectrometer. The commercial device used for our study is a Finnigan triple quadrupole mass spectrometer TSQ700 coupled to a multi-chamber equipment under UHV called " Dinamo " UHV Factory. To transform the TSQ700 in a low energy ion source, we studied the energy distribution of the ions at the exit of the analyzer by using the simulation software SIMION(r). This study revealed that the ion beam displays a high energy tail up to 1500 eV. The ion beam must then be filtered in energy in order to remove the high energy tail. To filter the ions in energy, we decided to add an electrostatic sector. The ion current measured at the output of electrostatic sector showed that the high-energy tail has been removed after this modification. The modified spectrometer was used to deposit CF3+ ions on a KBr(001) surface then characterized by Non-Contact Atomic Force Microscopy (NC-AFM) and Kelvin Probe Force Microscopy (KPFM). KPFM observations are consistent with the presence of positive charges
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Dika, Timbo Christelle. "Propriétés interfaciales des virus, concept de particules molles multicouches, corrélation avec les capacités d'adhésion." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0038/document.
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Propriétés interfaciales des virus, concept de particules molles multicouches, corrélation avec les capacités d'agrégation Hors de leur cellule hôte, les virus se comportent comme des particules biologiques inertes dont le comportement est principalement guidé par les propriétés physico-chimiques dites de surface, en particulier la charge et la balance hydrophile/hydrophobe. A l'heure actuelle, il est impossible de prédire le comportement de virus en arguant uniquement de leur charge de surface. Très récemment, des auteurs proposent que les virus devraient plutôt être assimilés à des particules molles perméables et fortement hétérogènes (Biophysical Journal 94, 2008, 3293) et non de simples sphères dures. L'objectif de ce travail est de caractériser les propriétés interfaciales des bactériophages selon le concept de particules molles multicouches afin de pouvoir les classer/hiérarchiser selon leur réactivité en terme de capacités d'adhésion sur des surfaces abiotiques ou leur agrégation. Les phages ARN F-spécifiques tout comme les virus entériques pathogènes sont constitués d'une capside protéique à l'intérieur de laquelle se trouve un génome à ARN. Dans un premier temps, il a été démontré que les éléments situés à l'intérieur de la capside ont une influence majeure sur les propriétés physico-chimiques en particulier électrocinétiques. En effet, nous avons comparé pour la première fois les propriétés électrohydrodynamiques de phages MS2 avec celles de Virus Like Particles correspondantes (VLPs, particules virales dépourvues de génome) dans différentes conditions de pH et de force ionique. Selon des principes précédemment établis et basés sur un formalisme pour l'électrophorèse de particules molles multicouches, on démontre entre autre que les phages complets portent une charge volumique plus importante que les VLPs. Les profils d'agrégation pour chaque type de particules sont différents avec une survenue de l'agrégation uniquement au point isoélectrique et à faible force ionique pour les VLPs, montrant ainsi l'impact du génome sur les propriétés de stabilité de suspensions virales. Nous avons ensuite caractérisé l'influence de la méthode de purification sur les différences observées de propriétés électrocinétiques et d'agrégation. La confrontation de trois méthodes distinctes révèle que les purifications par dialyse et par gradient de chlorure de césium maintiennent les différences de comportement entre les deux types de particules tandis que la précipitation au polyéthylène glycol atténue ces différences pour ce qui est des caractéristiques électrocinétiques mais les différences persistent au niveau du comportement d'agrégation. Dans une seconde partie nous avons d'une part étudié les propriétés interfaciales de différents virus ARN F-spécifiques (MS2, GA et Qbêta) à structures similaires. Au moyen du concept de particules molles multicouches, nous avons montré que les trois phages présentent une charge électrostatique similaire et leur degré d'hydrophobicité respectif est établi selon la séquence MS2 < Qbêta < GA, GA étant le plus hydrophobe. Ces propriétés ont ensuite été corrélées aux capacités d'adhésion sur des supports industriels (verre, inox, polypropylène) dont les propriétés de surface ont été caractérisées par AFM. L'étude met en évidence l'impact de la rugosité et de l'hydrophobicité des surfaces de dépôt qui tendent à augmenter l'adhésion virale. Des virus à structures multicouches différentes (Phi X 174, PRD1, MS2) ont également fait l'objet d'investigation en termes de propriétés électrocinétiques, d'agrégation et d'adhésion. Les résultats montrent la séquence suivante concernant la charge électrostatique Phi X 174 < PRD1 < MS2 (MS2 étant le plus chargé négativement). Par ailleurs, une corrélation positive entre ces propriétés et les capacités d'adhésion des phages sur des surfaces chargées et des supports strictement hydrophiles ou hydrophobes a été établieThe aim of this work is to characterize the interfacial properties of phages using the soft multilayer particles concept in order to interrelate appropriately their reactivity and their physico-chemical features. It was demonstrated that the RNA inside the capsid do have a major impact on the physico-chemical properties of the virus, in particular its electrophoretic mobility. We further compared electrohydrodynamic features of MS2 phage with those of the corresponding VLPs (virus particles without RNA). In line with theoretical predictions based on the soft particles concept, it is shown that MS2 are more negative than VLPs. The aggregation profiles of both particles significantly differ demonstrating the major influence of the genome on stability of viral suspensions. We then analyzed the influence of the virus purification method on the observed differences in terms of stability and electrohydrodynamics. We also studied the interfacial properties of phages exhibiting similar structures. It appeared that the phages display similar electrostatic charge while their hydrophobicity degree follows the sequence MS2
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Hazell, Gavin D. A. "Surface scattering from soft matter at interfaces." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.642031.
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The aim of this work has been to make use of surface scattering techniques to study soft matter at interfaces. The work presented herein is composed of two distinct bodies of work. The first comprises a fundamental study of the physical and structural properties of Langmuir monolayers composed of sulfobetaine surfactants. Physiochemical properties of the films have been investigated through the use of Langmuir trough techniques. This has been used to support x-ray and neutron reflectometry data, from which structural parameters were derived. The second body of work involves attempts to find and/or characterize novel ways of aligning proteins at interfaces. Soluble proteins at lipid interfaces have been characterized in terms of their interactions with functionalized lipid monolayers. Specific interactions have been utilized to adsorb protein layers at the interface through interactions with His-tag chelating lipids within the monolayer. These have been characterized using neutron reflectometry and quartz crystal microbalance studies. Work has also been completed to design a suitable system for the adsorption of membrane proteins. This has involved aligning phospholipid bilayer nanodiscs at the lipid interface and subsequent characterization through neutron reflectometry.
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Kehl, Catherine Eliza. "Soft Surface Grasping: Radular Opening in Aplysia Californica." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1544204621730828.
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Arnab, Sylvester. "Soft volume simulation using a deformable surface model." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/1932/.
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The aim of the research is to contribute to the modelling of deformable objects, such as soft tissues in medical simulation. Interactive simulation for medical training is a concept undergoing rapid growth as the underlying technologies support the increasingly more realstic and functional training environments. The prominent issues in the deployment of such environments centre on a fine balance between the accuracy of the deformable model and real-time interactivity. Acknowledging the importance of interacting with non-rigid materials such as the palpation of a breast for breast assessment, this thesis has explored the physics-based modelling techniques for both volume and surface approach. This thesis identified that the surface approach based on the mass spring system (MSS) has the benefits of rapid prototyping, reduced mesh complexity, computational efficiency and the support for large material deformation compared to the continuum approach. However, accuracy relative to real material properties is often over looked in the configuration of the resulting model. This thesis has investigated the potential and the feasibility of surface modelling for simulating soft objects regardless of the design of the mesh topology and the non-existence of internal volume discretisation. The assumptions of the material parameters such as elasticity, homogeneity and incompressibility allow a reduced set of material values to be implemented in order to establish the association with the surface configuration. A framework for a deformable surface model was generated in accordance with the issues of the estimation of properties and volume behaviour corresponding to the material parameters. The novel extension to the surface MSS enables the tensile properties of the material to be integrated into an enhanced configuration despite its lack of volume information. The benefits of the reduced complexity of a surface model are now correlated with the improved accuracy in the estimation of properties and volume behaviour. Despite the irregularity of the underlying mesh topology and the absence of volume, the model reflected the original material values and preserved volume with minimal deviations. Global deformation effect which is essential to emulate the run time behaviour of a real soft material upon interaction, such as the palpation of a generic breast, was also demonstrated, thus indicating the potential of this novel technique in the application of soft tissue simulation.
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Guttag, Mark A. (Mark Andrew). "Tunable surface topographies via particle-enhanced soft composites." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97851.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 75-76).
We introduce a new class of particle-enhanced soft composites (PESC) that can generate, on demand, custom and reversible surface topographies, with surface features that can be highly localized. These features can be specifically patterned or alternatively can be random in nature. Our PESC samples comprise a soft elastomeric matrix with stiff particles embedded below the surface. The surfaces of the samples presented in this thesis are originally smooth and flat but complex morphologies emerge under application of a stimuli (here we show application of primarily compressive loading). We demonstrate these adaptive surface topographies with both physical experiments and finite element simulations which are used to design and to study the mechanical response. A variety of different surface patterns can be attained by tailoring different dimensionless geometric parameters (e.g. different particle sizes, shapes, and distributions), as well as material properties. The design space of the system and the resulting surface topographies are explored and classified systematically. Given that our method depends primarily on the geometry of the particle arrays, our mechanism for on-demand custom surface patterning is applicable over a wide range of length scales. These surfaces can be used in a variety of different applications including control of fluid flow, adhesion, wettability and many others.
by Mark A. Guttag.
S.M.
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Nesser, Manar. "Influence of laser treatment with long, short, or ultra-short pulse duration on the magnetic properties and the domain structure of grain-oriented Iron-Silicon steels." Electronic Thesis or Diss., Amiens, 2021. http://www.theses.fr/2021AMIE0026.
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La technologie laser pulsé est l'une des solutions d'optimisation des propriétés électromagnétiques de certains aciers électriques. Cependant, son application industrielle pour différents alliages, différentes épaisseurs ou applications reste limitée. Par ailleurs, l'impact déterministe de cette technique sur la structure magnétique d'un matériau et sur ses performances nécessite des recherches approfondies. De plus, la technique d'ablation laser à impulsions ultra-courtes reste méconnue pour les aciers électriques. Elle représente cependant un potentiel important en terme de procédé reproductible et résilient aux élévations de température. L'objectif général de la thèse est d'étudier l'influence des traitements de surface par laser impulsionnel sur les propriétés magnétiques des aciers électriques de type Fer Silicium à Grains-Orientés afin d'améliorer leurs performances. Il est tout d'abord proposé une classification des différents procédés laser en fonction de la durée d'impulsion, de sa fréquence de répétition, de son intensité et de sa fluence. Trois familles de procédés sont retenues : l'irradiation, la gravure ou "scribing" et l'ablation. Une attention particulière sera portée sur ce dernier. Un des critères particulièrement analysé sera l'efficacité de la conversion d'énergie (i.e. surtout les pertes fer). Pour cela, l'impact de ces procédés laser est étudié à l'aide de modèles d'aimantation dynamique et de pertes, identifiés grâce à des mesures magnétiques par un banc dédié : le banc SST "Single Sheet Tester". Une optimisation des paramètres d'ablation laser est effectuée afin d'assurer une réduction des pertes fer de l'ordre de 20% tout en préservant la perméabilité magnétique en certains points de fonctionnement (inductions moyenne et forte à 50 Hz et basse induction jusqu’à 5000 Hz). Une étude complémentaire avec deux qualités différentes (FeSi GO conventionnel 0,23 mm et FeSi GO HiB 0,28 mm) a aussi permis d'adapter les paramètres et les motifs laser avec l'épaisseur du matériau. Il est également montré que le procédé d'ablation peut résister à des élévations de température supérieures aux autres procédés tout en acceptant l'application d'un revêtement isolant. En outre, une corrélation entre les paramètres énergétiques optiques (énergie d'une impulsion, densité d'énergie cumulative et densité de puissance pic) les motifs et impacts physiques des tracés laser (profondeur de gravures, zone affectée thermiquement, contrainte thermique induite ...) et finalement les paramètres magnétiques identifiés (coefficients de Bertotti ; paramètres du modèle Lambda) est présentée. Cette étude révèle certaines interprétations physiques. De plus, l'impact des traitements laser de surface sur la structure en domaines magnétiques a été analysé en visualisant le changement des domaines magnétiques. Des images magnéto-optiques par la technique MOIF "Magneto-Optical Indicator Film") sont présentés pour une vue d'ensemble sur les domaines principaux entre les tracés laser avec une résolution de l’ordre de 20 m. Des observations plus précises avec une résolution horizontale de l'ordre de 100 nm sont réalisées à l'aide du Microscope à Force Magnétique (MFM) afin d'avoir accès aux détails de cette structure à proximité et sur les tracés laser. Pour conclure, les analyses des paramètres d'ablation laser sont effectuées en assurant une réduction des pertes fer à 50 Hz avec un taux atteignant plus de 30 % pour une induction allant jusque 0,5 T et de l'ordre de 15 % au-dessus de 1,5 T. À plus haute fréquence et à 0,1 T, le taux de réduction peut dépasser 30%. Parallèlement, la perméabilité apparente peut soit être accrue en dessous de 1,2 T (coude de saturation), soit être préservée ou légèrement réduite entre 1,2 T et la saturation. Dans tous les cas, la polarisation J800 > 1,70 T (GO conventionnel) et J800 > 1,80 T (GO HiB) pour un champ magnétique de 800 A/m sera toujours garantie même après traitement laserPulsed laser technology is one of the productive solutions adopted to optimize the electromagnetic properties of certain electrical steels. However, its industrial application on different alloys, thicknesses, or applications remains restricted. Moreover, the deterministic impact of this technique on the magnetic structure of a material and its performance requires deep investigation. Further, the ultra-short pulsed laser ablation technique remains unfamiliar for electrical steels although it represents a vital potential in terms of a repeatable process that withstands high temperatures. The main intention of the thesis is to study the influence of surface laser treatments on the magnetic properties of grain-oriented silicon iron electrical steels in order to improve their performance. A classification of the different laser processes is proposed according to the pulse duration, repetition frequency, power, and laser fluence. Accordingly, three types of treatments are selected: irradiation, scribing, and ablation, with a particular emphasis on the ablation process. Remarkably, the principal criterion analyzed was the energy conversion efficiency (i.e. especially iron losses). On that account, the impact of these laser processes is studied using dynamic magnetization and loss models, identified by magnetic measurements with an SST "Single Sheet Tester" bench. Then, an optimization of the laser ablation parameters is carried out to ensure a reduction in iron losses of around 20% while maintaining the apparent permeability at certain operating points (medium and high inductions at 50 Hz and low inductions up to 5000 Hz). An additional study on two different grades of FeSi GO (conventional 0.23 mm and HiB 0.28 mm) permitted the adaptation of the laser parameters and patterns with the material thickness. Spectacularly, the ablation process has shown more resistance to a higher temperature than other processes. Furthermore, a correlation between the optical energy parameters (pulse energy, cumulative energy density, and peak power density), the patterns and laser impacts (groove depth, heat affected zone, induced thermal stress), and the identified magnetic parameters (Bertotti coefficients; Lambda model parameters) is presented. This study reveals some physical interpretations.Besides, the effect of surface laser treatments on the magnetic domain structure has been analyzed. We visualized the changes in magnetic domains with Magneto-optical images using the MOIF technique (Magneto-Optical Indicator Film) for an overview of the domains between the laser lines with a resolution of about 20 µm. Following this, more precise observations with a horizontal resolution of the order of 100 nm were performed using the Magnetic Force Microscope (MFM), which shows the structural details in the vicinity and in the laser tracing line. To conclude, an optimization of the laser ablation parameters is accomplished ensuring an iron loss reduction at 50 Hz with more than 30% for an induction 0.5 T, and a percentage of 15% for an induction above 1.5 T. At higher frequencies and for 0.1 T, the reduction percentage can exceed the 30%. Concurrently, the apparent permeability can either be enhanced below 1.2 T (saturation inclination) or slightly reduced between 1.2 T and saturation. Anyhow, the polarization J800 > 1.70 T (conventional GO) and J800 > 1.80 T (GO HiB) under a magnetic field of 800 A/m will be guaranteed after laser treatment
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Zareeipolgardani, Bahareh. "Surface reactivity of soft minerals at the atomic scale." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1018/document.
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Il est indispensable pour comprendre la diagenèse, i.e., la formation des roches sédimentaires, le durcissement des matériaux de construction hydrauliques comme le ciment ou le plâtre, ou la biominéralisation, d'identifier les mécanismes élémentaires de la cristallisation minérale. Le taux de réaction macroscopique des minéraux est généralement déduit de mesures de chimie des solutions. A côté de ces mesures macroscopiques, l'étude de la réactivité des minéraux inclut maintenant l'analyse des mécanismes atomiques a l'origine des réactions chimiques. Cela a été rendu possible depuis deux décennies par l'apparition d'outils capables d'observer des surfaces avec une résolution nanométrique, tels que la microscopie à force atomique et l'interférométrie à balayage vertical. Le gypse et la calcite font partie des minéraux dits mous. Ce sont des minéraux extrêmement répandus, que l'on peut trouver autant dans la nature sous forme de roches sédimentaires que dans le monde industriel. Le gypse (CaSO4,2H2O) est une évaporite dont les applications incluent la fabrication des plaques de plâtre, l'ajout au ciment Portland comme retardateur, l'élaboration du plâtre de Paris et l'amendement des sols. La sélénite ou l'albâtre sont des variétés de gypse utilisés comme matériaux pour l'ornement, mais leur faible dureté limite leur durabilité. La calcite, forme la plus stable de CaCO3, est un des principaux biominéraux, et un des constituants majeurs des roches des réservoirs carbonates, stockant naturellement de l'eau, du pétrole ou du gaz naturel. Quand les organismes biologiques font croitre leur coquille, ils contrôlent la morphologie, la taille, l'orientation et même la phase des cristaux de carbonates de calcium qui la constituent. Cela conduit à des biomatériaux présentant des propriétés physiques et chimiques qui diffèrent significativement de ceux de la calcite inorganique. Une connaissance plus approfondie des mécanismes sous-jacents à la réactivité de surface de la calcite et de l'effet des impuretés sur celle-ci permettra de nous rapprocher de la possibilité de synthétiser des minéraux biomimétiques, aux propriétés comparables à celles de la calcite biogénique. Dans ce contexte, ma thèse s'est développée dans trois directions. Dans la première, j'ai étudié l'influence d'une contrainte mécanique sur les mécanismes de dissolution. Mon objectif dans cette partie a été de tacher de déduire le taux de dissolution macroscopique à partir de la cinétique des mécanismes atomiques. La seconde partie de la thèse, la plus conséquente, a consisté à étudier l'influence d'une contrainte mécanique sur la croissance de la calcite, et à sonder le rôle d'un additif organique lors de cette croissance sous contrainte. Dans la troisième partie, je me suis penchée sur la dissolution de cristaux de calcite à l'aide de mesures topographiques quantitatives sur des aires relativement étendues de la surface des cristaux, dans une large gamme de pH. J'ai en particulier étudié l'influence d'un additif organique sur la dissolution et la cinétique de réaction à grande échelle. Les taux de dissolution macroscopique et microscopique, c'est-à-dire déduits de la dynamique d'évènements moléculaires (croissance de piqure d'attaque, migration de marche atomique), ne sont presque jamais en accord, même qualitativement, et l'élaboration d'une théorie générale liant la cinétique du phénomène aux deux échelles est encore en cours. Je présente ici des taux de dissolution microscopique du gypse, mesures par microscopie par force atomique (AFM), en accord quantitatif avec les taux de dissolution macroscopiques. Cet accord inédit a été obtenu en prenant soin de neutraliser le biais induit par le fait que la pointe AFM applique une force sur la surface qu'elle sonde, et en identifiant avec soin les mécanismes moléculaires majeurs à l'œuvre lors de la dissolution...[etc]Identifying reaction mechanisms of minerals is fundamental to understand diagenesis, i.e, sedimentary rock formation, construction material, like cement or gypsum, hardening, and biomineralization. The macroscopic reaction rates of minerals are generally deduced from solution chemistry measurements. Beside the measurement of macroscopic reaction rates, the study of the reactivity of minerals includes now the investigation of the atomic mechanisms involved in the reactions. This has been made possible for two decades by the use of tools resolving nanometric objects, such as vertical scanning interferometry (VSI) and atomic force microscopy (AFM). Gypsum and calcite are among soft minerals. They are extremely widespread mineral that can be found naturally in sedimentary rocks. They are also used in many industrial fields. Gypsum (CaSO4,2H2O) is an evaporate mineral. Gypsum uses include: manufacture of wallboards, plaster of Paris, soil conditioning, and hardening retarder in Portland cement. Varieties of gypsum known as "satin spar" and "alabaster" are used for a variety of ornamental purposes; however, their low hardness limits their durability. Calcite, the most stable crystalline form of CaCO3, is moreover important as a bio-mineral and a major constituent of host rock in carbonate reservoirs, which host drinking water and natural oil and gas. When biological organisms grow their shells, they control the crystal morphology, size, orientation and even the crystal phase of precipitated calcium carbonate. This results in materials with physical and chemical properties that differ significantly from those of inorganically precipitated calcite. Gaining more insight into the surface reactivity of calcite and the effect of surface impurities will bring us one step closer to being able to synthesize biomimetic material, which mimic the properties of biogenic calcite. In this thesis, I had three main focus points. In the first part I studied the effect of stress on the dissolution mechanisms. I investigated to deduce the dissolution rate from the atomic kinetics. The second and the most extensive was the study of the influence of stress on the calcite growth and probing the role of an organic additive on the dynamics of calcite growth while applying stress. In the third part I emphasised on quantitative topographic measurements of dissolving calcite crystal over a relatively large and fixed view at vast range of pH. I considered the influence of an organic additive on the dissolution and surface reaction kinetics at this larger scale. Both macroscopic and microscopic dissolution rates can also be deduced from the dynamics of molecular events (etch pit growth, atomic step migration), but they hardly ever agree, even qualitatively, and the elaboration of a general theory linking the kinetics at the two scales is still in progress. I presented here microscopic dissolution rates of gypsum, measured by atomic force microscopy (AFM), in quantitative agreement with macroscopic rates. This agreement has been obtained in taking care to neutralize the bias induced by the force applied by the AFM tip on the surface, and to identify clearly the driving molecular mechanism. The force applied by the AFM tip on the surface has been seen to increase the solubility of the mineral, thereby introducing a bias, so I have always worked with a constant and low applied force. This result shows that the determination, among the topographic changes during the dissolution of a mineral, of the dominant one, and the measurement of its dynamics, may permit deducing from AFM experiments a reliable macroscopic dissolution rate. The transformation of loose grains into a cohesive solid requires the crystallites to grow eventually constrained by the surrounding grains. Whereas never measured, this confinement and the associated stress is expected to influence noticeably the growth, and the final properties of the material… [etc]
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Levitt, Nicholas Paul. "Heterogeneous organic acid uptake on soot surfaces." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1235.
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Balog, Richard. "Low energy electrons as a soft tool for surface modification." [S.l. : s.n.], 2004. http://www.diss.fu-berlin.de/2004/263/index.html.
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Pihan, Sascha Alexander [Verfasser]. "Surface and bulk properties of soft nanocomposites / Sascha Alexander Pihan." Siegen : Universitätsbibliothek der Universität Siegen, 2011. http://d-nb.info/1017706220/34.
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Greenwood, Jedediah Drury 1977. "Three-dimensional analysis of surface settlement in soft ground tunneling." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29558.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.Includes bibliographical references (leaves 78-80).
A parametric study was performed to evaluate the effects of different construction variables on surface settlements above tunnels in soft ground. The finite element program "PLAXIS 3D Tunnel" was used to carry out the numerical analysis for the earth pressure balance (EPB) shield tunneling method in a saturated, normally consolidated clay. The two construction parameters that were varied were the face pressure and the grout pressure. Longitudinal settlement profiles were obtained for many different face pressures and several different grout pressures. Results show that the ground surrounding the tunnel is very sensitive to changes in grout pressure in terms of surface settlement and failure of the soil body, while a wide range of face pressures can be accommodated without failure. Furthermore, minimum surface settlement is achieved for a certain face pressure and becomes larger as the pressure is increased or decreased from that particular value, which for this analysis corresponded to an overload factor of one. Also, results show that surface settlement decreases with increasing grout pressure, as expected.
by Jedediah Drury Greenwood.
M.Eng.
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Kurt, Pinar. "Biotesting and Surface Science of Polyurethanes with Novel Soft Blocks." VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd_retro/13.
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Contact antimicrobial coatings with poly-alkylammonium compositions have been a subject of increasing interest in part because of the contribution of biocide release coatings to antibiotic resistance. Herein, a concept for antimicrobial coatings is developed based on thermodynamically driven surface concentration of soft block side chains. The concept incorporates structural and compositional guidance from naturally occurring antimicrobial proteins and achieves compositional economy via a polymer surface modifier (PSM). For this purpose, polyurethanes having P[AB] co-polyoxetane soft blocks, where A is a surface active (fluorous) or PEG-like side chain and B represents a desired function (alkylammonium) were prepared. Specifically, poly(2,2-substituted-1,3-propylene oxide) ran-co-telechelics with bromobutoxymethyl (CH2O(CH2)4Br) and either trifluoroethoxymethyl (3FOx, -CH2OCH2CF3)) or PEG-like (2-(2-methoxyethoxy)ethoxy)methyl (ME2Ox, (-CH2(OCH2CH2) 2OCH3)) side chains were prepared via cationic ring opening polymerization. Characterization utilized 1H NMR spectroscopy, temperature modulated differential scanning calorimetry (MDSC) and thermogravimetric analysis (TGA). Molecular weights (Mn) by 1H NMR end group analysis were ~6000-8000g/mole. Bromobutoxymethyl groups were completely substituted with N,N-dimethylalkyl amines to obtain alkylammonium co-telechelics. Two alkyl ammonium chain lengths, six carbons (C6) and twelve carbons (C12) were used. Tgs of bromobutoxymethyl co-telechelics were -68 degrees C and -48 degrees C for ME2Ox and 3FOx, respectively. Tgs remained low after amine substitution. Alkylammonium co-telechelics decomposed at 220-230 degrees C regenerating amine. Telechelics were incorporated into polyurethanes (PUs) having 4,4'-(methylene bis (p-cyclohexyl isocyanate) (H12MDI) and butanediol (BD) as the hard block (30wt%). Characterization by 1H NMR, GPC, MDSC and TGA is described. From DSC data, using the Fox equation, the weight fraction of pure soft block in the soft block domain (w1) was very high (0.96-0.99) for polyurethanes with fluorous soft blocks, while soft blocks with PEG-like side chains were phase mixed (w1 = 0.73-0.75). To our knowledge, this is the first time that a polycationic telechelic has been incorporated into a polyurethane. By using X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR-IR) spectroscopy, dynamic contact angle (DCA) analysis, sessile drop measurement, and Tapping Mode Atomic Force Microscopy (TM-AFM), surface properties of polyurethanes were examined. These polyurethanes were co-processed with base polyurethanes to modify surfaces. Surface concentration of 2 wt % P[AB]-polyurethanes was studied by using the same surface characterization methods. Surface concentration of semifluorinated and alkylammonium side chains (C6 and C12) was observed. Miscibility of PEG-like side chains resulted in weak concentration of short alkyl ammonium side chains (C6). However, longer alkylammonium side chains (C12) can 'self-chaperone' and surface concentrate better compared to shorter side chain analogs. For biocidal testing, aerosol and touch tests were designed and implemented. Coatings were tested for zone of inhibition. The polyurethanes were first tested as 100 wt % coatings and found to be highly effective against both Gram(-) (Pseudomonas aeruginosa, Escherichia coli) and Gram(+) (Staphylococcus aureus) bacteria. Polyurethane modified surfaces (2 wt %) were tested against aerosol challenges of the same bacteria strains. The 2 wt % PSM with soft block containing trifluoroethoxy (A, 89 mol %) and C12 alkylammonium (B, 11mol %) side chains gave the highest biocidal effectiveness against all bacteria strains in 30 min (100% kill, 3.6-4.4 log reduction).
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Stromback, Anna Christina. "A sub-surface evaluation of the Weissliegend facies, UK, southern North Sea." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250239.
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Canning, Gregory William. "Soft X-ray spectroscopic studies of surface films from oil additives." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39807.pdf.
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Hoffmann, William Darryle. "Study of Novel Ion/surface Interactions Using Soft-landing Ion Mobility." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc177214/.
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Preparative mass spectrometry is a gas-phase ion deposition technique aimed at deposition of monodisperse ion beams on a surface. This is accomplished through the implementation of a soft-landing ion mobility system which allows for high ion flux of conformationally selected ion packets. The soft-landing ion mobility system has been applied to a number of unique chemical problems including the deposition of insulators on graphene, the preparation of reusable surface enhanced Raman spectroscopic substrates, and the deposition of uranium nanoparticles. Soft-landing ion mobility provided a platform for the quick deposition of usable amounts of materials, which is the major objective of preparative mass spectrometry. Soft-landing ion mobility is unique when compared to other preparative mass spectrometric techniques in that the ion packets are conformationally separated, not separated on mass to charge ratio. This provides orthogonal complementary data to traditional mass spectrometric techniques and allows for the study of conformationally monodisperse surfaces. The diversity of problems that have been and continued to be explored with soft-landing ion mobility highlight the utility of the technique as a novel tool for the study of multiple ion/surface interactions.
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Henry, Kevin C. "Soft surface roll mechanics parameters for light vehicle rollover accident reconstruction /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2024.pdf.
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Henry, Kevin Claude. "Soft Surface Roll Mechanics Parameters for Light Vehicle Rollover Accident Reconstruction." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1436.
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Light vehicle rollover accidents on soft surfaces can be modeled assuming constant drag with linear motion equations and other engineering principles. The concept of using segment average results to evaluate roll mechanics parameters throughout a roll sequence, and specifically, segment duration to evaluate vehicle trajectory between ground impacts is developed. The trajectory model is presented, explained and compared to values obtained by analyzing digital video of rollover crash tests. Detailed film analysis procedures are developed to obtain data from rollover crash tests that are not otherwise documented. Elevation of the center of gravity of vehicles is obtained where instrumentation does not explicitly yield this data. Instantaneous center of gravity elevation data throughout a roll sequence provides the opportunity to calculate descend distances as a vehicle travels from one ground contact to another. This data is used to quantify severity of ground impacts as a vehicle interact with the ground throughout a roll sequence. Segment average analysis is a reasonable method for determining general roll mechanics parameters. Because of the chaotic nature of rollover accidents, the range of effective drag factors for a given roll surface may be quite large. Choosing an average of typical drag factors is a reasonable approach for a first-order approximation although certain parameters may be predicted less accurately than if actual values were known. The trajectory results demonstrate the influence of drag factor descent height calculations. Typical constant drag factors tend to overestimate descent height early in a roll sequence and underestimate descent height later in the sequence. The trajectory model is a useful tool to aid in understanding rollover mechanics although a rolling vehicle may be in contact with the ground for a significant fraction of a roll segment. The model should not be used at locations in roll sequences where there are extremes in translational center of gravity decelerations. These extremes include the segments immediately following overturn where there are large angular accelerations and large differences between the tangential velocity of the vehicle perimeter and the translational velocity of the center of gravity, as well as segments that include vehicle impacts with irregular topography.
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Pottier, Basile. "Les fluctuations de surface pour mesurer les propriétés de systèmes complexes en l'absence de sollicitation." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00936208.
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La dynamique des fluctuations thermiques d'un milieu révèle les propriétés de ce milieu, sans qu'il soit nécessaire de le solliciter. Afin d'exploiter ce principe, nous avons mis au point une technique optique destinée à mesurer des fluctuations spontanées de hauteur de surfaces libres, basée sur la mesure de la déflexion d'un laser réfléchi à la surface. Nous montrons que l'on peut ainsi mesurer les fluctuations de surface de milieux très variés, allant des liquides peu visqueux aux solides viscoélastiques. Les propriétés viscoélastiques du milieu sondé peuvent être déterminées à partir du spectre expérimental des fluctuations. On compare les valeurs obtenues avec des mesures rhéométriques conventionnelles, la technique s'avère être un moyen fiable pour caractériser les propriétés rhéologiques dans une gamme de fréquences allant de 0,1 Hz à quelques dizaines de kHz. Par ailleurs, on s'intéresse à l'influence du confinement sur les fluctuations de surface d'un liquide newtonien. On étudie l'effet du confinement en utilisant des substrats de différentes natures : solide plan, solide en relief et liquide. On montre que les fluctuations de surface dépendent fortement du substrat utilisé. On étudie en particulier le cas où le film liquide est déposé sur une surface solide plane. En créant un effet Marangoni induit par un gradient de température à la surface libre du liquide, on parvient à contrôler l'épaisseur du film sondé. On mesure ainsi les fluctuations de surface de films dont l'épaisseur varie entre 30 nanomètres et quelques micromètres. Les spectres mesurés sont sensibles à la condition hydrodynamique à l'interface liquide-solide et permettent d'évaluer une éventuelle longueur de glissement.
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Welch, Kyle. "Emergent thermodynamics in a system of macroscopic, chaotic surface waves." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20694.
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The properties of conventional materials are inextricably linked with their molecular composition; to make water flow like wine would require changing its molecular identity. To circumvent this restriction, I have contstructed and characterized a two-dimensional metafluid, so-called because its constitutive dynamics are derived not from atoms and molecules but from macroscopic, chaotic surface waves excited on a vertically agitated fluid. Unlike in conventional fluids, the viscosity and temperature of this metafluid are independantly tunable. Despite this unconventional property, our system is surprisingly consistent with equilibrium thermodynamics, despite being constructed from macroscopic, non-equilibrium elements. As a programmable material, our metafluid represents a new platform on which to study complex phenomena such as self-assembly and pattern formation. We demonstrate one such application in our study of short-chain polymer analogs embedded in our system.
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Schwaab, Daniel. "Surface patterning by means of soft lithography for molecular and bio-electronics." Jülich : Forschungszentrum, Zentralbibliothek, 2007. http://d-nb.info/987853880/34.
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Mirano, Geronimo (Geronimo J. ). "Jacobian-based control of soft robots for manipulation using implicit surface models." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113126.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 47).
Soft robot hands offer numerous advantages over rigid ones for manipulation, including robustness and safety. Yet, compared to rigid robots, soft robots are characterized by continuous mechanics, and finite-element approximations with many degrees of freedom present a significant obstacle for modern control approaches. The central question my thesis explores is whether we can capture the benefits of soft robot hands with relatively simple dynamical models. Specifically, we demonstrate a very simple model of a 2D soft manipulator that uses pulleys and cables to model deformable surfaces. This model captures much of the qualitative behavior of soft membranes, while also proving amenable to modern control techniques. We validate this model physically using a hardware set-up. We then demonstrate a simple quasi-static Jacobian controller which solves a second-order cone program to achieve the task of in-hand object repositioning.
by Geronimo Mirano.
M. Eng.
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Ahmadi, Mojtaba. "Mechanics of Surface Instabilities of Soft Nanofibers and Nonlinear Contacts of Hydrogels." Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31861.
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The research of this dissertation is formulated in two fields, i.e., the theoretical and computational studies of circumferential wrinkling on soft nanofibers and the swelling mechanics study of a bi-layered spherical hydrogel containing a hard core.
Continuous polymer nanofibers have been massively produced by means of the low-cost, top-down electrospinning technique. As a unique surface instability phenomenon, surface wrinkling in circumferential direction is commonly observed on soft nanofibers in electrospinning. In this study, a theoretical continuum mechanics model is developed to explore the mechanisms of circumferential wrinkling on soft nanofibers under uniaxial stretching. The model is able to examine the effects of elastic properties, surface energy, and fiber radius on the critical axial stretch to trigger circumferential wrinkling and to discover the threshold fiber radius to initiate spontaneous wrinkling. In addition, nonlinear finite element method (FEM) is further adopted to predict the critical mismatch strain to evoke circumferential wrinkling in core-shell polymer nanofibers containing a hard core, as a powerful computational tool to simulate controllable wrinkling on soft nanofibers via co-electrospinning polymer nanofibers incorporated with nanoparticles as the core. The studies provide rational understanding of surface wrinkling in polymer nanofibers and technical approaches to actively tune surface morphologies of polymer nanofibers for particular applications, e.g. high-grade filtration, oil-water separation, polymer nanocomposites, wound dressing, tissue scaffolding, drug delivery, and renewable energy harvesting, conversion, and storage, etc.
Furthermore, hydrogels are made of cross-linked polymer chains that can swell significantly when imbibing water and exhibit inhomogeneous deformation, stress, and, water concentration fields when the swelling is constrained. In this study, a continuum mechanics field theory is adopted to study the swelling behavior of a bi-layered spherical hydrogel containing a hard core. The problem is reduced into a two-point boundary value problem of a 2nd-order nonlinear ordinary differential equation (ODE) and solved numerically. Effects of material properties on the deformation, stress, and water concentration fields of the hydrogel are examined. The study offers a rational route to design and regulate hydrogels with tailorable swelling behavior for practical applications in drug delivery, leakage blocking, etc.
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Haguet, Julie. "Gliding of a way soft elastomer on a lubricated hard glass surface." Grenoble INPG, 2010. http://www.theses.fr/2010INPG0162.
Full textAbstract:
Les matériaux constitutifs des seringues destinées à l'industrie pharmaceutique peuvent entraîner des interactions indésirables avec les solutions médicamenteuses qu'elles contiennent. Lors du glissement d'un joint de piston dans le corps d'une seringue, les matériaux utilisés, la géométrie des différents éléments ainsi que les conditions expérimentales déterminent la mécanique du glissement. L'étude du glissement d'un joint de piston en élastomère mou dans un corps de seringue en verre lubrifié a été réalisée. L'influence de différents paramètres sur les forces de frottement tels que la viscosité et la quantité du lubrifiant et la nature de l'élastomère, a été étudiée. Cette étude couplée à une modélisation a permis de mettre en évidence des paramètres clés qui gouvernent la forme générale d'une courbe de glissement tels que la déformation du joint de piston et le cisaillement de l'huile. De plus, la condition nécessaire pour obtenir un pic d'activation sur les courbes de glissement est d'avoir une variation du coefficient de frottement qui suit une courbe de StribeckPrefillable syringes for the pharmaceutical industry are made of different kinds of materials which can have undesirable interactions with the medicinal solutions present inside the syringe barrel. When a plunger stopper glides inside a syringe barrel, the materials used and the geometry of the different elements influence the gliding mechanics. The study of the gliding of a wavy elastomeric plunger stopper inside a siliconized glass barrel has been done. The influence of various parameters on the gliding forces, as the viscosity and the quantity of the lubricant, and the nature of the elastomer has been studied. This experimental study has been coupled to a modelization which has enabled to emphasize some critical parameters that govern the general shape of a gliding curve as the deformation of the stopper and the shear of the silicone oil. A necessary condition to obtain an activation peak for the gliding curves is to have a friction coefficient that follows a Stribeck-like variation
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Tian, Yuan TIAN. "How to Measure Work of Adhesion and Surface Tension of Soft Materials." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1523295919890025.
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