Rozprawy doktorskie: „Surface characterizations”

1

Murauski, Anatoli. "Surface and liquid crystal interlayer interactions : characterizations and applications /". View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20MURAUS.

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2

Po, Jiunn Hong. "Synthesis and characterizations of 2D nanoparticles with controlled folding for circularly polarized optical properties". Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLS047.

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Appartenant aux semi-conducteurs II-VI, les nanoplaquettes de chalcogénure de cadmium présentent des caractéristiques optiques fines dans la région visible. Ces particules peuvent mesurer jusqu'à des centaines de nanomètres en longueur et en largeur, tout en présentant quelques nanomètres le long de leur dimension d'épaisseur sous confinement quantique. Lors de la fonctionnalisation des ligands en surface sur ces nanofeuillets ultrafins, des corps sous contrainte résiduelle sont créés. Cela provient du désaccord entre le réseau cristallin inorganique et la couche d'ancrage des atomes, en plus de la répulsion stérique induite par les chaînes aliphatiques. Ces trois composants agissants sont capturés via une analyse mécanique quantitative pour aboutir à un modèle permettant de prédire l’enroulement des nanoplaquettes. Les rayons résultants des nanohélices peuvent être ajustés en faisant varier linéairement les longueurs de chaîne organique associées, pour une population d'épaisseur donnée de nanoplaquettes. Malgré la contrainte de surface importante induite par les groupes thiolates, le paramètre de maille dans le plan des nanocristaux reste en moyenne égal à celui du zinc blende massif, comme le démontrent des expériences et des simulations par diffraction des rayons X à grand angle. L'orientation spécifique de ces objets anisotropes et déformés reflète un impact sur la forme et l'intensité de leurs pics correspondants en diffraction.Les moyens d'obtenir des nanoplaquettes de chalcogénure de cadmium présentant des propriétés chiroptiques en absorption sont abordés. La voie la plus prometteuse consiste à substituer les carboxylates achiraux en surface par des énantiomères chiraux de l'acide tartrique. Les valeurs de dissymétrie semblent augmenter avec le nombre de stéréocentres et présentent des signaux polarisés beaucoup plus forts avec les groupes fonctionnels de carboxylate qu'avec thiolate. Ces formes de courbe de type absorptif associées à la longueur d'onde de transition excitonique du cœur inorganique, résultent d'un effet d'hybridation entre leur niveau de trous et l'orbital moléculaire des ligands. D'autre part, les hélices de silice chirales décorées d'or, synthétisées à partir de l'auto-assemblage des molécules de tensioactif type gemini, sont également capables de démontrer le dichroïsme circulaire dans leur région de résonance plasmonique. Cela augmente avec la force du couplage plasmonique interparticulaire, en accord avec les simulations réalisées selon l'approximation des dipôles discrets. Une ouverture vers le tri des objets chiraux par optoacoustophorèse est documentée. Cette preuve de concept démontre de différentes vitesses de migration en moyenne dans le plan entre les énantiomères chiraux séparés, en fonction des conditions de travail acoustiques et optiques. L'effet de la forme et de la concentration des particules en solution montre qu'en cas d’empilement, la compressibilité d'un objet peut conduire à des comportements d'auto-organisation similaires à ceux des matières actives, des bactéries et des cellules
Belonging to II-VI semiconductors, cadmium chalcogenide nanoplatelets exhibit narrow optical features in the visible region. These particles can measure up to hundreds of nanometers in length and width, while presenting a few nanometers along their quantum confined thickness direction. During surface functionalization of ligands onto these ultrathin nanosheets, residually stressed bodies are created. This originates from the mismatch between the inorganic crystal lattice and layer of anchoring atoms, in addition to the steric repulsion brought by aliphatic chains. These three acting components are captured via a quantitative mechanical analysis to result in a model that allows for the prediction of curling in nanoplatelets. The resulting nanohelices radii are shown to be able to be tuned by linearly varying the associated organic chain lengths, for a given thickness population of nanoplatelets. Despite the important surface stress induced by thiolate headgroups, the average in-plane lattice parameter of these nanocrystals remains equal to that of zinc blende bulk as demonstrated experimentally and theoretically by wide-angle X-ray diffraction. Specific orientation of these anisotropic and distorted objects reflects an impact on the form and intensity of their corresponding scattered peaks.Ways to obtaining cadmium chalcogenide nanoplatelets that display chiroptical properties in absorption are addressed. The most promising route consists in substituting pristine surface achiral carboxylates by chiral enantiomers of tartaric acid. The dissymmetry values appear to increase with the number of stereocenters and show much stronger polarized signals with carboxylate than thiolate functional groups. These absorptive-like line shapes associated to the excitonic transition wavelength of the inorganic core, result from a hybridization effect between their hole level and the ligands’ molecular orbital. On the other hand, gold decorated chiral silica helices, synthesized from the benefit of the gemini surfactant molecules’ self-assembly, are also capable of exhibiting circular dichroism in their plasmon resonance region. This increases with the strength of the interparticle plasmonic coupling, in agreement with simulations performed under discrete dipole approximation. An opening towards sorting chiral objects via optoacoustophoresis is documented. This proof-of-concept demonstrates distinct average in-plane migration speeds between separate chiral enantiomers, as a function of the acoustics and optical working conditions. The effect of particles’ shape and concentration in solution show that upon jamming, an object’s compressibility can lead to self-organizing behaviors similarly to cases of active matters, bacteria and cells

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Liu, Juan. "Electrochemical Characterizations and Theoretical Simulations of Transport Behaviors at Nanoscale Geometries and Interfaces". Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/chemistry_diss/74.

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Since single nanopores were firstly proposed as a potential rapid and low-cost tool for DNA sequencing in 1990s (PNAS, 1996, 93, 13770), extensive studies on both biological and synthetic nanopores and nanochannels have been reported. Nanochannel based stochastic sensing at single molecular level has been widely reported through the detection of transient ionic current changes induced by geometry blockage due to analytes translocation. Novel properties, including ion current rectification (ICR), memristive and memcapacitive behaviors were reported. These fundamental properties of nanochannels arise from the nanoscale dimensions and enables applications not only in single molecule sensing, but also in drug delivery, electrochemical energy conversion, concentration enrichment and separation, nanoprecipitation, nanoelectronics etc. Electrostatic interactions at nanometer-scale between the fixed surface charges and mobile charges in solution play major roles in those applications due to high surface to volume ratio. However, the knowledge of surface charge density (SCD) at nanometer scale is inaccessible within nanoconfinement and often extrapolated from bulk planar values. The determination of SCD at nanometer scale is urgently needed for the interpretation of aforementioned phenomena. This dissertation mainly focuses on the determination of SCD confined at a nanoscale device with known geometry via combined electroanalytical measurements and theoretical simulation. The measured currents through charged nanodevices are different for potentials with the same amplitude but opposite polarities, which deviates away from linear Ohm's behavior, known as ICR. Through theoretical simulation of experiments by solving Poisson and Nernst-Planck equations, the SCD within nanoconfinement is directly quantified for the first time. An exponential gradient SCD is introduced on the interior surface of a conical nanopre based on the gradient distribution of applied electric field. The physical origin is proposed based on the facilitated deprotonation of surface functional groups by the applied electric field. The two parameters that describe the non-uniform SCD distribution: maximum SCD and distribution length are determined by fitting high- and low-conductivity current respectively. The model is validated and applied successfully for quantification and prediction of mass transport behavior in different electrolyte solutions. Furthermore, because the surface charge distribution, the transport behaviors are intrinsicaly heterogeneous at nanometer scale, the concept is extended to noninvasively determine the surface modification efficacy of individual nanopore devices. Preliminary results of single molecule sensing based on streptavidin-iminobiotin are included. The pH dependent binding affinity of streptavidin-iminobiotin binding is confirmed by different current change signals ("steps" and "spikes") observed at different pHs. Qualitative concentration and potential dependence have been established. The chemically modified nanopores are demonstrated to be reusable through regenerating binding surface.

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Jaabar, Ilhem Lilia. "Surface characterizations to investigate osteoarticular mesenchymal tissues : new insights to monitor the extracellular matrix remodeling at the supramolecular level". Electronic Thesis or Diss., Sorbonne université, 2022. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2022SORUS145.pdf.

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Un tissu conjonctif est un ensemble coopératif de cellules différenciées enchevêtrées dans une matrice extracellulaire (ECM). Cette dernière, particulièrement abondante, se compose principalement de protéines, telles que les collagènes, et d'un gel visqueux constitué d'eau et de protéoglycanes chargés négativement. Tous les tissus conjonctifs subissent un renouvellement constant de leur ECM, préservant ainsi l'intégrité et les propriétés des tissus. Des perturbations dans le remodelage de l'ECM, en termes de composition ou de structure supramoléculaire, peuvent avoir un impact significatif sur l'intégrité du tissu et sur ses propriétés biomécaniques, entraînant ainsi des dysfonctionnements et le développement de pathologies. Cependant, le remodelage de l’ECM est souvent étudié par des techniques biochimiques standards qui ne permettent pas de fournir des informations à l’échelle supramoléculaire. Sonder l’organisation de l’ECM à cette échelle peut contribuer significativement à la compréhension de la nature des processus biologiques et physicochimiques impliqués dans le remodelage pathologique de l’ECM. Dans cette objectif, nous avons développé une approche méthodologie originale permettant la caractérisation de tissus biologiques par des techniques de caractérisation de surface telle que l’AFM et l’XPS. Dans une première étude, l'AFM a été utilisé pour étudier l'effet de la procédure de réticulation UV/riboflavine sur la structure et les propriétés mécaniques de capsules d'épaule malades, qui sont principalement constituées de fibrilles de collagène de type I. Les résultats montrent que la procédure de réticulation a modifié les propriétés biomécaniques des capsules malades, en augmentant la rigidité des tissus sans modification de la structure et de la viabilité cellulaire.Dans une deuxième étude, nous avons étudier le remodelage de l’ECM du cartilage articulaire humain au cours de l’arthrose. Pour ce faire, nous avons caractérisé la composition, la structure et les propriétés mécaniques à différents degrés de sévérité d’arthrose par XPS et AFM. Les résultats ont permis de mettre en évidence deux phases : (1) une tentative de réparation, et (2) une dégradation irréversible du cartilage. Par ailleurs, des modifications structurales similaires à celles observées dans le cartilage arthrosique ont été observé sur des échantillons non arthrosiques traités enzymatiquement. Nos travaux ont donc permis de souligner le rôle central de l'équilibre homéostatique sur la progression de l’arthrose. Dans une troisième, un éventail de techniques de caractérisation moléculaire, biochimique et physicochimique a été utilisé pour déterminer la dynamique de minéralisation et les modifications de l’ECM au cours de la différenciation hypertrophique des chondrocytes. Cette étude a permis de montrer que la différenciation hypertrophique des chondrocytes préhypertrophiques induit un remodelage de l’ECM qui précède la minéralisation. Les analyses chimiques ont, par ailleurs, révélé que les minéraux nouvellement formés sont de l'hydroxyapatite faiblement cristallisée. La cartographie chimique révèle également la présence de débris cellulaires riches en phosphore. Ces derniers semblent être générés par l'apoptose croissante des chondrocytes
A connective tissue is a cooperative set of differentiated cells entangled in an extracellular matrix (ECM). The latter, which is particularly abundant, is composed mainly of proteins, such as collagens, and a viscous gel made up of water and negatively charged polysaccharides: proteoglycans. All connective tissues undergo a constant renewal of their ECM, thus preserving the integrity and properties of the tissue. Disturbances in ECM remodeling, in terms of composition or supramolecular structure, can have a significant impact on tissue integrity and biomechanical properties, leading to dysfunction and the development of pathologies. However, ECM remodeling is often studied by standard biochemical techniques that do not provide information at the supramolecular scale. Probing the organization of the ECM at this scale can contribute significantly to the understanding of the nature of the biological and physicochemical processes involved in pathological ECM remodeling. To this end, we have developed an original methodological approach allowing the characterization of biological tissues by surface characterization techniques such as AFM and XPS.In a first study, AFM was used to study the effect of the UV/riboflavin cross-linking procedure on the structure and mechanical properties of diseased shoulder capsules, which are mainly composed of type I collagen fibrils. The results show that the cross-linking procedure modified the biomechanical properties of the diseased capsules, increasing tissue stiffness without altering the structure and cell viability.In a second study, we investigated the remodeling of human articular cartilage ECM during OA. To do so, we characterized the composition, structure and mechanical properties at different degrees of OA severity by XPS and AFM. The results revealed 2 phases: (1) a repair attempt, and (2) an irreversible degradation of the cartilage. Moreover, structural modifications similar to those observed in osteoarthritic cartilage were observed on non-osteoarthritic samples treated with enzymes. Our work has thus highlighted the central role of homeostatic balance in the progression of OA.In a third study, a range of molecular, biochemical and physicochemical characterization techniques were used to determine the mineralization dynamics and ECM modifications during hypertrophic differentiation of chondrocytes. This study showed that hypertrophic differentiation of prehypertrophic chondrocytes induces ECM remodeling that precedes mineralization. Chemical analyses further revealed that the newly formed minerals are weakly crystallized hydroxyapatite. Chemical mapping also reveals the presence of phosphorus-rich cellular debris. The latter seem to be generated by the increasing apoptosis of chondrocytes

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Kutluer, Kutlu. "Electrical, Optical, And Noise Characterizations Of Mwir Type-ii Inas/gasb Superlattice Single Pixel Detectors". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614737/index.pdf.

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Detection of mid-wavelength infrared radiation is crucial for many industrial, military and biomedical applications. Photon detectors in the market can operate at only low temperature which increases weight, power consumption and total cost. Type-II InAs/GaSb superlattice infrared detectors are expected to have a major role in the infrared detector market with providing high quality detection characteristics at higher temperatures. Therefore, in the past decade, there has been an increasing interest in infrared detectors based on type-II InAs/GaSb superlattice technology due to their long range adjustable bandgap, low tunneling current and Auger recombination rates which bring potential of high temperature operation. Characterization of this photodiodes requires detailed investigations on different aspects. This study focuses on various optical and electrical characterization techniques for single pixel infrared detectors: responsivity characterization using FTIR and blackbody source, dark I-V and R-V characterizations, response time measurement. Characterizations of detector noise with respect to frequency and bias voltage are studied in detail. These characterization techniques are carried out in order to observe the effects of design with three different &ldquo
standard&rdquo
and a new &ldquo
N&rdquo
structure designs and also to understand the effects of surface passivation with atomic layer deposited Al2O3 layer and ordinary PECVD deposited Si3N4 and SiO2 layers. When standard photodiodes are compared, we observed that the one with the thickest active absorber region has the highest response and dark current density values. &ldquo
N&rdquo
structure design photodiode has very low dark current density while its optical performance is not as high as the standard designs. Si3N4 passivation degrades both optical and electrical performances. SiO2 and Al2O3 passivation layers improve optical and electrical characteristics of photodiodes. Theoretical and experimental dark current noise values of SiO2 passivated sample in agreement up to 0.18V reverse bias while those values of unpassivated and Si3N4 passivated samples agree only at zero bias. Temperature dependent R-V characteristics of photodiodes are analyzed and the surface limited activation energy is calculated in order to investigate the additional noise. At the end, surface recombination noise is proposed to cover the deficit on the noise calculation.

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Peyroux, Jérémy. "Développement de films extrudés à propriétés spécifiques grâce aux technologies de traitement de surfaces : fluoration, plasma et combinaisons". Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22547.

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En raison de leurs nombreux avantages, les matériaux polymères sont aujourd'hui reconnus comme des éléments essentiels de notre quotidien. Ils composent une quantité importante d'objets de la vie courante dans lesquels ils ont souvent substitué les substances naturelles initialement utilisées. Néanmoins, pour une utilisation dans le domaine de l’emballage, ces matériaux présentent des contraintes non négligeables qui nécessitent une recherche permanente. L’amélioration et l’optimisation des propriétés d’imprimabilité, barrières aux gaz et de machinabilité représentent un enjeu crucial pour répondre aux nouvelles réglementations, législations mais aussi phénomènes sociétaux et exigences industrielles. La solution d'étude retenue ici est de traiter la surface de matériaux commerciaux. Les différents traitements plasma, relativement bien maitrisés sur ce type de matériaux, ont été combinés avec des procédés de fluoration, plus originaux. La fluoration directe est ainsi apparue comme une solution privilégiée du fait de son efficacité avérée sur ce type de matériaux. La maitrise des différents paramètres intrinsèques à chaque procédé a permis d’identifier l’unicité de chaque traitement et combinaison afin d’ajuster, non seulement la morphologie, mais surtout la composition de surface des films traités en fonction des propriétés ciblées. Des caractérisations spectroscopiques ont tout d’abord été mises en place pour identifier les mécanismes associés à chacun de ses traitements seuls ou combinés. La morphologie des surfaces a également été caractérisée par des techniques classiques de microscopie. Enfin, l’étude des propriétés résultantes et leur stabilité dans le temps ont permis de mettre en évidence l’intérêt de ces procédés pour améliorer les propriétés actuelles des films d’emballages et leur stabilité ; notamment leur imprimabilité, et leur comportement barrière aux gaz
Currently, polymeric materials are currently well-recognized as essential elements of our daily life due to the advantages that they exhibit, in which they can replace the originally natural products. However, the use of these materials for packaging applications has still significant drawbacks. The interest of research on polymeric materials is potentially required in order to provide a good compromise of properties such as printability, gas barrier and machinability. Aims are to follow the new regulations, laws, but also societal phenomena and industrial phenomena.In this study, surface treatments were directly applied on material polymers dedicated to packaging applications. Plasma treatments, relatively well mastered, were combined with original fluorination processes. In comparison, direct fluorination was effectively used to increase polymer properties. Each treatment and their combination were carried out with various intrinsic parameters under control to adjust both surface morphology and surface composition of treated polymers according to targeted film properties.Spectroscopic characterizations were first monitored to identify the mechanisms associated with each treatment (alone or in combination). Surface morphology was also observed on standard microscopic techniques. The resulting properties and their long-termed stability were carried. These studies highlight the effectiveness of those treatments to improve the current properties of packaging films and stability: including printability, and barrier properties

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Gakis, Giorgos. "Modélisation multi-échelles et analyse expérimentale de l'ALD d'alumine : interactions entre dynamique du procédé, chimie de surface et phénomènes interfaciaux". Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0097.

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Le rétrécissement continu des dispositifs microélectroniques exige la production des couches nanométriques uniformes et conformes, avec une pureté chimique et des interfaces abruptes. Le dépôt de couche atomique (ALD) est un procédé favorable à la production de tels films. Tirant ses avantages de la nature auto-limitante des réactions, ALD peut permettre un contrôle de l’épaisseur à la monocouche, produisant des films de haute pureté. Bien que l'ALD présente de nombreux avantages, des inconvénients se rencontrent lors du dépôt de films de quelques nanomètres. En particulier, la croissance initiale en îlots et la formation d'une couche interfaciale sont deux de ses limitations principales, en particulier dans le cas du dépôt d’oxyde métallique sur Si. De plus, le dépôt sur des grandes surfaces n'est pas toujours uniforme et dépend du réacteur et des conditions du procédé. Ces inconvénients doivent être supprimés afin de déposer des films d'oxydes sur Si, essentiels pour la production de transistors à effet de champ du futur. Dans cette thèse, l'ALD de Al2O3 de TMA et H2O sur Si est étudiée de manière approfondie, afin de remédier aux inconvénients ci-dessus. L'étude consiste en une approche multi-échelles numérique et expérimentale combinée. Quatre modèles numériques différents ont été développés pour traiter différentes échelles d'espace. Un ensemble de techniques de caractérisation a été utilisé, notamment l'ellipsométrie, XRR, TEM, STEM, EDX, XPS et SIMS. Dans ce cadre, les phénomènes détaillés sont illuminés, ce qui permet de comprendre le processus et l'origine des inconvénients de l'ALD. La compétition entre la désorption et les réactions de surface, s'est avérée être le facteur limitant pour le dépôt à basse température, jusqu'à 200°C. La concentration des sites réactifs en surface limite le dépôt à des températures supérieures à 300°C. Bien que l’ALD soit conçu comme un processus dépendant uniquement de la chimie de surface, l’analyse des phénomènes de transport à l’intérieur du réacteur a montré que la conception du réacteur et du processus peut affecter la distribution des réactifs et la température à l’intérieur du réacteur ALD. L'approche multi-échelles et le couplage entre les différents modèles numériques ont révélé que l'interaction entre les mécanismes de surface et les phénomènes de transport avait un effet sur l'uniformité du dépôt. En utilisant cette approche numérique, il est possible de dériver des conditions optimales garantissant une uniformité du film. Au cours des premières étapes, le dépôt du film est inhibée, ce qui a conduit à un régime de croissance en îlots. L'analyse intégrée a montré que 25 cycles d'ALD sont nécessaires pour déposer un film continu de Al2O3. Au cours de ce régime, l'oxydation interfaciale a conduit à la formation d'une couche d'oxyde interfacial d'environ 2 nm, composée de SiOx, AlOx et SixOyAl, qui altère les propriétés et donc les applications potentielles de la structure déposée. Un prétraitement in situ au plasma N2-NH3 du substrat de Si a été introduit, conduisant à la formation d'une couche de SixNyH sur la surface du substrat. Le prétraitement a augmenté la réactivité de surface, et la période d’inhibition était limitée. Une croissance linéaire est obtenue après 5 cycles. En outre, l'oxydation interfaciale du Si a été réduite, car la couche SixNyH s'est avérée servir de barrière efficace pour la diffusion de l' O et l'oxydation du Si. Le travail présenté dans cette thèse montre la nécessité de telles approches intégrées pour analyser les phénomènes impliqués dans l'ALD. Telles études permettent une compréhension approfondie des mécanismes, afin de proposer des solutions pour lutter contre les inconvénients apparus lors des premières étapes de dépôt. Cela pourrait permettre a l’ ALD de produire des couches minces nanométriques uniformes et conformes de grande pureté avec des interfaces abruptes, capables de répondre aux exigences de l’industrie électronique
The constant shrinking of microelectronic devices requires the production of conformal and uniform nanometric thin films, with a high chemical purity and abrupt interfaces. In this context, Atomic Layer Deposition (ALD) has emerged as a favorable process to produce such films. Drawing its advantages from the self-limiting nature of the surface reactions involved, ALD can yield thickness control down to the monolayer, producing conformal films of high purity. Although ALD has many advantages, drawbacks arise when depositing films of some nanometers. In particular, the initial island growth and the formation of an interfacial oxide layer are two of its main limitations, especially for the case of metal oxide ALD on Si. Moreover, the deposition on large area wafers is not always uniform, and depends on the reactor and process design. These drawbacks need to be suppressed in order to establish ALD as the adequate process for the deposition of high-k gate oxides on Si, essential for the production of field effect transistors of the future. In this thesis, the ALD of Al2O3 from TMA and H2O on Si is thoroughly investigated, in order to tackle the above drawbacks. The investigation consists of a combined multiscale computational and experimental approach. Four different numerical models were developed dealing with different space scales. A complete set of characterization techniques was used, including ellipsometry, XRR, TEM, STEM, EDX, XPS and SIMS. Using this framework, the detailed phenomena involved are illuminated, thus allowing to better understand the process and identify the factors responsible for the drawbacks of ALD. The competition between surface mechanisms, namely desorption and surface reactions, was found to be the limiting factor for deposition at low temperatures, up to 200oC. The concentration of surface reactive sites was found to limit the deposition at higher temperatures up to 300oC. Although ALD is conceived as a process depending only on surface chemistry, the analysis of the transport phenomena inside the ALD chamber showed that the reactor and process design can affect the reactant and temperature distribution inside the ALD reactor. The multiscale approach and the coupling among the different computational models revealed that the interplay between surface mechanisms and transport phenomena affects the film uniformity. Using this computational approach, it was possible to derive optimal process conditions that ensure maximum film uniformity. During the first deposition steps, the film deposition was found to be inhibited, leading to an island growth regime. The integrated analysis showed that 25 cycles are needed in order to deposit a continuous Al2O3 film. During this regime, interfacial oxidation of the Si substrate led to the formation of a ~2 nm interfacial oxide layer, consisting of SiOx, AlOx, and Al-silicates, which degrades the properties and thus the potential applications of the deposited structure. An in situ N2-NH3 plasma pretreatment of the HF-cleaned Si substrate was introduced, leading to a formation of a SixNyH layer on the substrate surface. The pretreatment was found to enhance the surface reactivity, as the inhibition period was restricted and linear ALD growth was obtained even after 5 cycles. Furthermore, interfacial Si oxidation was reduced, as the SixNyH layer was found to serve as an effective barrier for O diffusion and Si oxidation. The work presented in this thesis demonstrates the necessity of such integrated approaches to analyze the detailed phenomena involved in ALD. Such studies help in the thorough understanding of the ALD mechanisms, and consequently in elaborating solutions which restrict the drawbacks arising during the initial deposition steps. This could pave the way for the ALD process to industrially produce uniform and conformal nanometric thin films of high purity and abrupt interfaces, able to answer to the demands of the future electronic industry

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Gür, Fatih Nadi. "Plasmonic waveguides self-assembled on DNA origami templates: from synthesis to near-field characterizations". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-235762.

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Manipulating light by controlling surface plasmons on metals is being discussed as a means for bridging the size gap between micrometer-sized photonic circuits and nanometer-sized integrated electronics. Plasmonic waveguides based on metal nanoparticles are of particular interest for circumventing the diffraction limit, thereby enabling high-speed communication over short-range distances in miniaturized micro-components. However, scalable, inexpensive fine-tuning of particle assemblies remains a challenge and near-field probing is required to reveal plasmonic interactions. In this thesis, self-assembled waveguides should be produced on DNA scaffolds. DNA origami is an extremely versatile and robust self-assembly method which allows scalable production of nanostructures with a fine control of assemblies at the nanoscale. To form the plasmonic waveguides, six-helix bundle DNA origami nanotubes are used as templates for attachment of highly monodisperse and monocrystalline gold nanoparticles with an inter-particle distance of 1-2 nm. In the first part of this thesis, the effects of parameters which are involved in assembly reactions are systematically investigated. The assembly yield and binding occupancy of the gold nanoparticles are determined by an automated, high-throughput image analysis of electron micrographs of the formed complexes. As a result, unprecedented binding site occupancy and assembly yield are achieved with the optimized synthesis protocol. In addition, waveguides with different sizes of gold nanoparticles and different inter-particle distances, quantum dots attachments to the waveguides and multimerization of the waveguides are successfully realized. In the second part of this thesis, direct observation of energy transport through a self-assembled waveguide towards a fluorescent nanodiamond is demonstrated. High-resolution, near-field mapping of the waveguides are studied by electron energy loss spectroscopy and cathodoluminescence imaging spectroscopy. The experimental and simulation results reveal that energy propagation through the waveguides is enabled by coupled surface plasmon modes. These surface plasmon modes are probed at high spatial and spectral resolutions. The scalable self-assembly approach presented here will enable the construction of complex, sub diffraction plasmonic devices for applications in high-speed optical data transmission, quantum information technology, and sensing
Die Manipulation des Lichts durch die Kontrolle von Oberflächenplasmonen auf metallischen Oberflächen und Nanopartikeln gilt als vielversprechende Methode zur Überbrückung der Größen-Lücke zwischen Mikrometer-großen photonischen und nanometer-großen elektronischen Schaltkreisen. Plasmonische Wellenleiter basierend auf metallischen Nanopartikeln sind vom besonderen Interesse, da sie die Umgehung des Beugungslimits und somit eine Hochgeschwindigkeitskommunikation über kurze Distanzen in immer kleiner werdenden Schaltkreisen ermöglichen könnten. Allerdings ist die skalierbare und kostengünstige Anordnung von Partikeln eine große Herausforderung und es werden Nahfelduntersuchungen benötigt um plasmonische Interaktionen detektieren zu können. Das Ziel dieser Arbeit ist die Selbstassemblierung von multi-partikel Wellenleitern auf DNA Gerüsten. Die Verwendung von DNA-Origami bietet eine äußerst vielseitige Plattform zur skalierbaren Herstellung von Nanostrukturen mittels Selbstassemblierung und ermöglicht eine präzise Kontrolle der Anordnungen im Nanobereich. Für den Aufbau der plasmonischen Wellenleiter werden DNA-Origami Nanoröhren, bestehend aus sechs Helices als Templat für die Anbindung von monodispersen und monokristallinen Goldnanopartikeln mit einem interpartikulären Abstand von 1-2 nm verwendet. Im ersten Abschnitt dieser Arbeit werden die beeinflussenden Faktoren dieser Assemblierungsreaktion systematisch untersucht. Die Ausbeute der assemblierten Strukturen und die Besetzung der Bindungsstellen werden durch eine automatisierte und effiziente Bildanalyse von Elektronenmikroskopieaufnahmen ausgewertet. Durch die Entwicklung eines optimierten Syntheseprotokolls werden bisher unerreichte Assemblierungsausbeuten ermöglicht. Zusätzlich erfolgen die experimentelle Realisierung von Strukturen mit verschieden großen Goldnanopartikeln und unterschiedlichen interpartikulären Abständen, sowie die Anbindung von Quantenpunkten an die Wellenleiter und eine Verknüpfung der assemblierten Strukturen. Der zweite Abschnitt dieser Dissertation befasst sich mit der Untersuchung des Energietransports in selbstassemblierten Wellenleitern über einen fluoreszierenden Nanodiamanten. Dazu erfolgen hochaufgelöste Nahfeldmessungen der Wellenleiter mittels Elektronenenergieverlustspektroskopie und Kathodolumineszenz-mikroskopie. Die experimentellen Ergebnisse und zusätzlich durchgeführte Simulationen bestätigen eine durch gekoppelte Oberflächenplasmonenmoden induzierte Weitergabe der Energie innerhalb des Wellenleiters. Diese Oberflächenplasmonenmoden werden bei hoher räumlicher und spektraler Auflösung untersucht. Das hier umgesetzte Konzept der Selbstassemblierung wird den Aufbau komplexer plasmonischer Geräte für Anwendungen im Bereich der optischen Hochgeschwindigkeitsdatenübertragung, der Quanteninformations-technolgie und der Sensorik ermöglichen

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9

Andrews, Marilyn Mockus 1958. "Characterization of the surface acidity of passivated iron particles by flow microcalorimetry". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276614.

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The characteristics of passivated iron particles have been examined with flow microcalorimetry to determine the acidic nature of the surface sites. The molar heat of adsorption of pyridine from hexane was measured with a FMC and a differential refractive index detector, at 23 and 40°C. The adsorption data were found to obey the assumptions of the Freundlich isotherm. The adsorption densities at different temperatures were used to calculate the isosteric heat of adsorption. The molar heat of adsorption of triethylamine from hexane was also measured and combined with the data for pyridine in order to calculate the Drago constants for the iron particles. A static adsorption method was used for the adsorption of pyridine from hexane onto the iron particles, for comparison with the dynamic method. The heat of wetting for the iron particles, with hexane, has also been measured. The iron particles were examined with X-ray diffraction. Mossbauer spectroscopy, XPS, SEM, TEM, and electrophoresis to characterize the surface layer. These techniques have revealed that the iron particles are coated with ferric oxide and this surface is amphoteric in aqueous solutions.

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Hakim, Ali. "Characterization of Hard Metal Surfaces after Various Surface Process Treatments". Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12433.

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The aim of this thesis is to investigate how material surfaces are affected by various surface treatments and how this relates to the adhesion of the coating. The materials that were studied were WC-Co and Cermets and the surface treatments used were polishing, grinding with coarser and finer abrasive grains, and finally wet blasting and dry blasting. Focus was on deformations and residual stresses in the surface, surface roughness and cracks. The test methods used for examining the samples included surface roughness measurements, residual stress measurements, adhesion tests using Rockwell indentation and SEM images of the surface and the cross section.

The results concluded that polishing gives very good adhesion. Additionally, the adhesion for ground surfaces was good for WC-Co but very poor for Cermets. Furthermore, it was observed that finer abrasive grains did not result in better adhesion. In fact, the coarser grains gave slightly better results. Finally, it was concluded that wet blasting has a clear advantage over dry blasting and results in much better adhesion, especially for the Cermets. The results for the WC-Co were a bit inconsistent and so further research is required.

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Yang, Hongta. "Fundamentals, preparation, and characterization of superhydrophobic wood fiber products". Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24796.

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Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Yulin Deng; Committee Member: Jeffery S. Hsieh; Committee Member: Sujit Banerjee; Committee Member: Zhong Lin Wang.

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Zhang, Jinhong. "Surface Forces between Silica Surfaces in CnTACl Solutions and Surface Free Energy Characterization of Talc". Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/29997.

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In general, the stability of suspension can be studied using two methods. One is to directly measure the forces between two interacting surfaces in media. The other is to study the interfacial surface free energies of the particles in suspension. Direct surface force measurements were conducted between silica surfaces in octadecyltrimetylammonium chloride (C₁₈TACl) solutions using an Atomic Force Microscope (AFM). The results showed that the hydrophobic force existed in both air-saturated and degassed C₁₈TACl solutions. The attraction decreased with NaCl addition, and was the strongest at the point of charge neutralization (p.c.n.) of silica substrate. The force measurement results obtained in C_nTACl solutions showed that the attractions decayed exponentially and became the maximum at the p.c.n.'s. The decay lengths (D) increased with surfactant chain length. The measured forces were fitted to a charged-patch model of Miklavic et al. (1994) with rather large patch sizes. It was also found that the decay length decreased linearly with the effective concentration of the CH2/CH3 groups raised to the power of -1/2. This finding is in line with the model of Eriksson et al. (1989). It suggested that the long-range attractions are hydrophobic forces originating from the changes in water structure across a hydrophobic surface-solution interface. For the TiO₂/water/TiO₂ system, the Hamaker constant was found to be 4±1×10^-20 J. The force curves obtained in the TiO₂/C_nTACl system showed a repulsion-attraction-repulsion transition with increasing surfactant concentration. The long-range attraction observed between TiO₂ surfaces in C_nTACl solutions reached maximum at the p.c.n., and the decay length increased with chain length. In present work, the thin-layer wicking technique was used to determine the surface free energy (γ_s) and its components of talc samples. The results showed that the basal surfaces of talc are weakly basic while the edge surfaces are acidic. The effect of chemicals on the surface free energies of talc was systemically studied. The results showed that CMC (carboxymethyl cellulose sodium salt) and EO/PO (ethylene oxide/propylene oxide) co-polymers made talc surface hydrophilic by increasing the surface free energies, especially γ^LW and γ^-. SOPA (sodium polyacrylate) increased greatly the zeta-potentials instead of the surface free energies.
Ph. D.

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13

De, Zorzi Chiara <1976&gt. "Physico-chemical Characterization of Glass Surfaces: New Surface-related Analytical Approaches". Master's Degree Thesis, Università Ca' Foscari Venezia, 2021. http://hdl.handle.net/10579/20493.

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Since ancient times glass was used as storage material for ointments, medicinal remedies and cosmetics for its properties of inertness and product protection. Along the centuries the technology has developed dedicated glasses for pharmaceutical use, improving their mechanical and chemical performances up to the modern borosilicate glasses. Meanwhile the technology is trying to meet the needs of new complex and sensitive drugs, the necessity of new analytical approaches has increased for a better overview of the content-material interactions to complement the classical pharmacopoeia analysis. From this perspective a physico-chemical analytical approach, focused on the glass surface as main player of the drug-content interactions, is the main topic of this study. The application of surface dedicated complementary techniques as XPS, SIMS and SEM was investigated, permitting the characterization of the glass surface in terms of morphology, composition and depth elemental overview. As preliminary part of a more complex project, this study focused on the comparison and baseline characterization of the raw materials with the related finished containers, highlighting interesting surface features and glass composition-related peculiarities. This work confirms the suitability of these analytical techniques to pave the way for further studies on long term storage or environmental effects, helping to define a possible correlation with drug interactions phenomena.

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Burton, Zachary Travis. "Surface characterization, adhesion, and friction properties of hydrophobic leaf surfaces and nanopatterned polymers for superhydrophobic surfaces". Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1160489659.

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Walton, Ryan J. "Characterization of Road Surfaces Using High Resolution 3D Surface Scans to Develop Parameters for Predicting Tire-Surface Friction". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531432167496958.

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Nygren, Patrik. "De Novo Design and Characterization of Surface Binding Peptides - Steps toward Functional Surfaces". Licentiate thesis, Linköping University, Linköping University, Sensor Science and Molecular Physics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8992.

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The ability to create surfaces with well-defined chemical properties is a major research field. One possibility to do this is to design peptides that bind with a specific secondary structure to silica nanoparticles. The peptides discussed in this thesis are constructed to be random coil in solution, but are “forced” to become helical when adsorbed to the particles. The positively charged side-chains on the peptides strongly disfavor an ordered structure in solution due to electrostatic repulsion. When the peptides are introduced to the particles these charges will strongly favor the structure because of ion pair bonding between the peptide and the negatively charged nanoparticles. The peptide-nanoparticle system has been thoroughly investigated by systematic variations of the side-chains. In order to determine which factors that contributes to the induced structure, several peptides with different amino acid sequences have been synthesized. Factors that have been investigated include 1) the positive charge density, 2) distribution of positive charges, 3) negative charge density, 4) increasing hydrophobicity, 5) peptide length, and 6) by incorporating amino acids with different helix propensities. Moreover, pH dependence and the effect of different nanoparticle curvature have also been investigated. It will also be shown that the system can be modified to incorporate a catalytic site that is only active when the helix is formed. This research will increase our understanding of peptide-surface interactions and might be of importance for both nanotechnology and medicine.

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17

Borgh, Annika. "Biomimetic surfaces : Preparation, characterization and application". Doctoral thesis, Linköpings universitet, Sensorvetenskap och Molekylfysik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8492.

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I denna avhandling beskrivs tillverkning, karaktärisering och tillämpning av ett antal biomimetiska ytor. Biomimetik är att härma naturen och grundtanken är att titta på hur naturen löst liknande problemställningar. Två olika typer av modellsystem med inspiration från naturen har tagits fram för framtida tillämpningar inom bioanalys, biosensorer samt antifrysmaterial. Det ena typen av modellsystem innefattar fosforylerade ytor och det andra består av ytor som härmar antifrys(glyko)proteiner. Ytorna tillverkades av monolager av självorganiserande svavelorganiska molekyler och karaktäriserades före tillämpning med hjälp av ellipsometri, IR-spektroskopi, kontaktvinkelmätning och röntgenfotoelektronspektroskopi. Modellsystemen för att studera vattenfrysning på ytor inspirerades av antifrys(glyko)proteiner som bl.a. kan hittas i polarfiskar. Två modellsystem utvecklades och studerades med avseende på frysning av kondenserat vatten. Det ena designades att härma den aktiva domänen hos ett antifrysglykoproteiner (AFGP) och det andra härmade typ I antifrysproteiner (AFP I). Frysstudierna visade på signifi-kanta skillnader för AFGP-modellen jämfört med ett (OH/CH3) referenssystem med jämförbar vätbarhet, men inte för AFP Imodellen. Vattnet frös vid högre temperatur för AFGPmodellen. Modellsystemen med fosforylerade ytor inspirerades av fosforylering och biomineralisering. Två system utvecklades, ett med långa och ett med korta alkylkedjor på aminosyraanalogerna, både med och utan fosfatgrupp. En ny metod användes med skyddsgrupper på fosfaterna hos de långa analogerna innan bildandet av monolager. Skyddsgrupperna togs bort efter bildandet av monolager. Dessa monolager undersöktes också med elektrokemiska metoder och signifikant högre kapacitans observerades för de fosforylerade monolageren jämfört med de icke fosforylerade.
This thesis describes the preparation, characterization and application of a few biomimetic surfaces. Biomimetics is a modern development of the ancient Greek concept of mimesis, i.e. man-made imitation of nature. The emphasis has been on the preparation and characterization of two types of model systems with properties inspired by nature with future applications in bioanalysis, biosensors and antifreeze materials. One type of model system involves phosphorylated surfaces; the other consists of surfaces mimicking antifreeze (glyco)proteins. The surfaces were made by chemisorbing organosulfur substances to a gold surface into monomolecular layers, so called self-assembled monolayers (SAMs). The physicochemical properties of the SAMs were thoroughly characterized with null ellipsometry, contact angle goniometry, x-ray photoelectron spectroscopy and infrared spectroscopy prior to application. The work on antifreeze surfaces was inspired by the structural properties of antifreeze (glyco)proteins, which can be found in polar fish. Two model systems were developed and studied with respect to ice nucleation of condensed water layers. One was designed to mimic the active domain of antifreeze glycoproteins (AFGP) and the other mimicked type I antifreeze proteins (AFP I). Subsequent ice nucleation studies showed a significant difference between the AFGP model and a (OH/CH3) reference system displaying identical wetting properties, whereas the AFP I model was indistinguishable from the reference system. The model systems with phosphorylated surfaces were inspired from phosphorylations and biomineralization. Two systems were developed, short- and long-chained amino acid analogues, with and without a phosphate group. A novel approach with protected groups before attachment to gold were developed for the long-chained analogues. The protective groups could be removed successfully after assembly. The long-chained SAMs were evaluated with electrochemical methods and significantly higher capacitance values were observed for the phosphorylated SAMs compared to the non-phosphorylated.

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van, Rensburg Wilma. "Characterization of natural antimicrobial peptides adsorbed to different matrices". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97929.

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Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Biofouling is the attachment and biofilm formation that leads to negative repercussions such as persistent post-harvest infections, infections obtained from medical implants and continual surface contamination of food processing plants. Much of the problem lies with the resistance that develops against conventional treatments due to the formation of mature biofilms. Thus the focus has shifted from the removal of biofilms to the prevention of initial attachment of organisms. This entails the use of antimicrobial surfaces that either have an inherent antimicrobial activity, e.g. certain metals, or surfaces that are modified by the attachment of antimicrobial agents. The attachment of antimicrobial agents can either be through covalent bonding or adsorption, depending on the intended use of the surface as well as the mode of action of the antimicrobial agent. Antimicrobial peptides (AMPs) are ubiquitous in nature, tend to have a broad spectrum of activity, are very stable and have been shown to maintain activity when covalently bound to solid surfaces. Tyrocidines (Trcs), antimicrobial peptides produced by Bacillus aneurinolyticus, are cyclodecapeptides with a broad spectrum of activity against Grampositive bacteria, fungi, yeasts and the human malaria parasite, Plasmodium falciparum. The aim of this study was to determine the antimicrobial activity of surfaces treated with a tyrocidine extract, under which conditions the activity remained stable and to look into possible applications of these peptide-treated surfaces. The study focussed on different solid surfaces namely mixed cellulose, polyvinylidene fluoride, polycarbonate, cellulose acetate, cellulose (paper)(CL) and high density cellulose packing material (HDC), as a pilot study to assess the antimicrobial activity of Trc and gramicidin S (GS) treated solid surfaces. Peptide desorption and subsequent analysis by mass spectrometry was used to confirm the presence and integrity of the Trcs adsorbed. Scanning electron microscopy was utilised to show that the adsorbed peptides did not affect the structural integrity of the treated filters. However, it was shown that the adsorbed peptides changed the hydrophobic/hydrophilic character by means of a wettability assay. A cell viability assay and erythrocyte assay were developed from existing methodologies to determine the biological activity of the AMP-functionalised polymeric material. Seven of the AMP treated solid surfaces showed antimicrobial activity when challenged with >105 Micrococcus luteus cells/cm2. Although the polycarbonate filter lost antimicrobial activity at the high cell concentrations, it was shown to have potent antimicrobial activity at lower cell concentrations. Complete inhibition of M. luteus growth was observed for both the gramicidin S and tyrocidine extract treated high density cellulose and cellulose filters. Stability tests showed that the tyrocidines remained adsorbed to cellulose filters and biologically active when exposed multiple water washes, water washes at different temperatures (25°C - 100°C) and pH changes (pH 1-12). The antimicrobial activity was only affected after exposure to the water wash of pH 13 which is possible due to susceptibility of the CL filters to high pH solvents. A preliminary study on the effect of Trcs treated CL filters on the sterilization, germination and effect on tomato seedlings was conducted. It was found that Trcs had no effect on the germination and did not fully sterilise the seeds or environment against fungi. However, it was observed that 5 μg/mL Trcs treated filters promoted root length opposed to the toxic effect seen with filters treated with higher Trc concentrations. It is hypothesised that Trcs prefer to bind to hydrophilic surfaces exposing the hydrophobic residues and the cationic residue of the peptide to interact with the bacterial membrane to elicit its antimicrobial response. The exposed residues contain some of the hydrophobic residues and the cationic Orn9/Lys9, which are crucial to the antimicrobial activity of the peptides. Hydrophobic interaction is particularly important for the haemolytic activity which is currently the only viable method of detection of the adsorbed Trcs. Trcs also have a preference for adsorption onto cellulose and cellulose analogues which points to possible application in protective food wrapping and wood surface protection. Trcs maintains its antimicrobial activity regardless of adsorption to solid surfaces. It can therefore be concluded that Trcs treated solid surfaces hold great potential in preventing the initial bacterial colonization and subsequent biofilm formation. Antimicrobial peptide enriched solid surfaces can thus be developed and tailored to a specific application such as filters, catheters and packaging materials.
AFRIKAANSE OPSOMMING: Biovervuiling is die aanhegting en vorming van biofilms met negatiewe gevolge soos aanhoudende na-oes infeksies, infeksies op mediese inplantings en voortdurende oppervlak besoedeling van voedselverwerkings fabrieke. Die probleem lê grotendeels by die weerstand wat ontwikkel word teen konvensionele behandelings as gevolg van die vorming van volwasse biofilms. Die fokus het gevolglik verskuif vanaf die verwydering van biofilms na die voorkoming van aanvanklike aanhegting van organismes aan oppervlaktes. Dit behels die gebruik van antimikrobiese oppervlaktes wat of 'n inherente antimikrobiese aktiwiteit het, bv. sekere metale óf oppervlaktes wat aangepas is deur die aanhegting van antimikrobiese middels. Die aanhegting van antimikrobiese agente kan of deur kovalente binding óf adsorpsie plaasvind, afhangende van die beoogde gebruik van die oppervlak, sowel as die metode van werking van die antimikrobiese agent. Antimikrobiese peptiede (AMPe) is alomteenwoordig in die natuur, is geneig om 'n breë spektrum van aktiwiteit te hê, is baie stabiel en het getoon dat aktiwiteit in stand gehou word wanneer dit kovalent gebind word op soliede oppervlaktes. Tirosidiene (Trcs), antimikrobiese peptiede wat deur Bacillus aneurinolyticus geproduseer word, is siklodekapeptiede met 'n breë spektrum van aktiwiteit teen Gram-positiewe bakterieë, swamme, giste en die menslike malaria parasiet Plasmodium falciparum. Die doel van hierdie studie was om die antimikrobiese aktiwiteit te bepaal van oppervlaktes wat met 'n tirosidien ekstrak behandel is, te bepaal onder watter omstandighede die aktiwiteit stabiel bly en om te soek na moontlike toepassings van hierdie peptied-behandelde oppervlaktes. Die studie het gefokus op verskillende soliede oppervlaktes naamlik gemengde sellulose, polyvinylidene fluoried, polikarbonaat, sellulose asetaat, sellulose (papier)(CL) en 'n hoë digtheid sellulose verpakkings materiaal (HDC), as 'n loodsstudie om die antimikrobiese aktiwiteit van die Trcs en gramisidien S (GS) behandelde soliede oppervlaktes te ondersoek. Peptied-desorpsie en daaropvolgende ontleding deur massaspektroskopie is gebruik om die teenwoordigheid en integriteit van die geadsorbeerde Trcs te bevestig. Skandering elektronmikroskopie is gebruik om aan te toon dat die geadsorbeerde peptiede geen invloed op die strukturele integriteit van die behandelde filters het nie. Daar is egter getoon dat die geadsorbeerde peptiede die hidrofobiese / hidrofiliese karakter verander. „n Lewensvatbaarheid selgebaseerde toets en eritrosiet toets is ontwikkel uit bestaande metodes om die biologiese aktiwiteit van die AMP-gefunktionaliseerde polimeriese materiaal te bepaal. Sewe van die AMP behandel soliede oppervlaktes het antimikrobiese aktiwiteit getoon wanneer dit met > 105 Micrococcus luteus selle/cm2 gedaag is. Hoewel die polikarbonaat filter antimikrobiese aktiwiteit met hoë sel konsentrasies verloor het, is dit getoon dat dit wel uitgeproke antimikrobiese aktiwiteit het teen laer konsentrasies selle. Volledige inhibisie van M. luteus groei is waargeneem vir beide die hoë digtheid sellulose en sellulose filters wat met GS en tirosidien ekstrak behandel is. Stabiliteit toetse het getoon dat die tirosidiene geadsorbeer en biologies aktief op sellulose filters bly nadat dit blootgestel is aan verskeie water was-stappe, waterwasse by verskillende temperature (25 °C -100 °C) en pH veranderinge (pH 1-12). Die antimikrobiese aktiwiteit was net beïnvloed ná blootstelling aan die water met 'n pH 13, wat moontlik is te danke aan die vatbaarheid van die CL filters by hoë pH oplosmiddels is. 'n Voorlopige studie is gedoen om die uitwerking van Trcs behandelde CL filters op die sterilisasie, ontkieming en tamatiesaailinge te bepaal. Daar is gevind dat Trcs geen effek op die ontkieming het nie, maar dat dit nie volledig die sade en omgewing steriliseer vir fungiese groei nie. Daar is egter waargeneem dat 5 μg/mL Trcs behandelde filters wortel lengte van die saailinge bevorder teenoor die giftige uitwerking soos waargeneem vir die filters wat met hoër konsentrasies Trcs behandel is. Dit word gepostuleer dat Trcs verkies om aan hidrofiliese oppervlaktes te bind wat die van die hidrofobiese aminosure en die kationiese residu van die peptied blootstel om aan die bakteriële membraan te bind om gevolglik antimikrobiese reaksie te ontlok. Die blootgestelde deel bevat sommige van die hidrofobiese residue en positiewe Orn9/Lys9 wat noodsaaklik vir die antimikrobiese aktiwiteit van die peptiede. Die hidrofobiese interaksies is veral belangrik vir die hemolitiese aktiwiteit wat tans die enigste bruikbare metode van opsporing van die geadsorbeerde Trcs is. Trcs het ook 'n tendens vir adsorpsie op sellulose en sellulose analoë wat dui op die moontlike toepassing in beskermende voedselverpakking en die beskerming van houtoppervlaktes. Trcs handhaaf hul antimikrobiese aktiwiteit, ongeag van adsorpsie aan soliede oppervlaktes. Dit kan dus afgelei word dat Trcs-behandelde soliede oppervlaktes die potensiaal het om die aanvanklike kolonisasie van bakterië te voorkom en die daaropvolgende biofilm vorming. Antimikrobiese peptied verrykde soliede oppervlaktes kan dus ontwikkel en aangepas word vir gebruik in spesifieke toepassing soos in filters, kateters en verpakkingsmateriaal.

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Pacquentin, Wilfried. "Contribution à l'étude des propriétés physico-chimiques des surfaces modifiées par traitement laser : application à l'amélioration de la résistance à la corrosion localisée des aciers inoxydables". Phd thesis, Université de Bourgogne, 2011. http://tel.archives-ouvertes.fr/tel-00676332.

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Les matériaux métalliques sont utilisés dans des conditions de plus en plus sévères et doivent présenter une parfaite intégrité sur des périodes de plus en plus longues. L'objectif de ce travail de thèse est d'évaluer le potentiel d'un traitement de refusion laser pour améliorer la résistance à la corrosion d'un acier inoxydable de type 304L ; l'utilisation du laser dans le domaine des traitements de surface constituant un procédé en pleine évolution à cause des changements récents dans la technologie des lasers. Dans le cadre de ce travail, le choix du laser s'est porté sur un laser nano-impulsionnel à fibre dopée ytterbium dont les caractéristiques permettent la fusion quasi-instantanée sur quelques microns de la surface traitée, immédiatement suivie d'une solidification ultra-rapide avec des vitesses de refroidissement pouvant atteindre 1011 K/s. La combinaison de ces processus favorise l'élimination des défauts surfaciques, la formation de phases hors équilibre, la ségrégation d'éléments chimiques et la formation d'une nouvelle couche d'oxyde dont les propriétés sont gouvernées par les paramètres laser. Afin de les corréler avec la réactivité électrochimique de la surface, l'influence de deux paramètres laser sur les propriétés physico-chimiques de la surface a été étudiée : la puissance du laser et le taux de recouvrement des impacts laser. Pour clarifier ces relations, la résistance à la corrosion par piqûration des surfaces traitées a été déterminée par des tests électrochimiques. Pour des paramètres laser spécifiques, le potentiel de piqûration d'un acier inoxydable de type 304L augmente de plus de 500 mV traduisant ainsi une meilleure tenue à la corrosion localisée en milieu chloruré. L'interdépendance des différents phénomènes résultant du traitement laser a rendu complexe la hiérarchisation de leur effet sur la sensibilité de l'alliage testé. Cependant, il a été montré que la nature de l'oxyde thermique formé au cours de la refusion laser et ses défauts sont du premier ordre pour l'amorçage des piqûres.

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20

Malagon, Nieto Camilo. "3D characterization of acidized fracture surfaces". Texas A&M University, 2003. http://hdl.handle.net/1969.1/5771.

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The complex interrelations among the different physical processes involved in acid fracturing make it difficult to design, and later, to predict the outcome of stimulation jobs. Actual tendencies require the use of computational models to deal with the dynamic interaction of variables. This thesis presents a new study of acidized surface textures by means of a laser profilometer to improve our understanding of the remaining etched surface topography and its hydraulic response. Visualization plots generated by the profilometer identified hydrodynamic channels that could not be identified by the naked eye in acidized surfaces. The plots clarified the existence of rock heterogeneities and revealed how the processes of dissolution function in chalk rock. Experimental data showed clearly that the effect of dissolution depends on the type of rock and the fluid system; dolomite, for example, dissolves more rapidly but more roughly than limestone. Fluid leakoff rate and temperature also affect the dissolution. Further research is necessary to clarify the effects of conductivity.

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21

Sager, Benay. "Stereolithography Characterization for Surface Finish Improvement: Inverse Design Methods for Process Planning". Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04092006-155545/.

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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2006.
Dr. David W. Rosen, Committee Chair ; Dr. Farrokh Mistree, Committee Member ; Dr. W. Jack Lackey, Committee Member ; Dr. Cliff Henderson, Committee Member ; Dr. Ali Adibi, Committee Member.

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22

Mogrovejo, Carrasco Daniel Estuardo. "Enhancing Pavement Surface Macrotexture Characterization". Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51957.

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One of the most important objectives for transportation engineers is to understand pavement surface properties and their positive and negative effects on the user. This can improve the design of the infrastructure, adequacy of tools, and consistency of methodologies that are essential for transportation practitioners regarding macrotexture characterization. Important pavement surface characteristics, or tire-pavement interactions, such as friction, tire-pavement noise, splash and spray, and rolling resistance, are significantly influenced by pavement macrotexture. This dissertation compares static and dynamic macrotexture measurements and proposes and enhanced method to quantify the macrotexture. Dynamic measurements performed with vehicle-mounted lasers have the advantage of measuring macrotexture at traffic speed. One drawback of these laser devices is the presence of 'spikes' in the collected data, which impact the texture measurements. The dissertation proposes two robust and innovative methods to overcome this limitation. The first method is a data-driven adaptive method that detects and removes the spikes from high-speed laser texture measurements. The method first calculates the discrete wavelet transform of the texture measurements. It then detects (at all levels) and removes the spikes from the obtained wavelet coefficients (or differences). Finally, it calculates the inverse discrete wavelet transform with the processed wavelet coefficients (without outliers) to obtain the Mean Profile Depth (MPD) from the measurements with the spikes removed. The method was validated by comparing the results with MPD measurements obtained with a Circular Texture Meter (CTMeter) that was chosen as the control device. Although this first method was able to successfully remove the spikes, it has the drawback that it depends on manual modeling of the distribution of the wavelet coefficients to correctly define an appropriate threshold. The next step of this dissertation proposes an enhanced to the spike removal methodology for macrotexture measurements taken with high-speed laser devices. This denoising methodology uses an algorithm that defines the distribution of texture measurements by using the family of Generalized Gaussian Distributions (GGD), along with the False Discovery Rate (FDR) method that controls the proportion of wrongly identified spikes among all identified spikes. The FDR control allows for an adaptive threshold selection that differentiates between valid measurements and spikes. The validation of the method showed that the MPD results obtained with denoised dynamic measurements are comparable to MPD results from the control devices. This second method is included as a crucial step in the last stage of this dissertation as explained following. The last part of the dissertation presents an enhanced macrotexture characterization index based on the Effective Area for Water Evacuation (EAWE), which: (1) Estimates the potential of the pavement to drain water and (2) Correlates better with two pavement surface properties affected by macrotexture (friction and noise) that the current MPD method. The proposed index is defined by a three-step process that: (1) removes the spikes, assuring the reliability of the texture profile data, (2) finds the enveloping profile that is necessary to delimit the area between the tire and the pavement when contact occurs, and (3) computes the EAWE. Comparisons of current (MPD) and proposed (EAWE) macrotexture characterization indices showed that the MPD overestimates the ability of the pavement for draining the surface water under a tire.
Ph. D.

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23

Ecevit, Tuba Safiye. "Synthesis And Characterization Of Surface Sulfonated Polypropylene". Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/3/12604846/index.pdf.

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ABSTRACT SYNTHESIS AND CHARACTERIZATION OF SURFACE SULFONATED POLYPROPYLENE FILMS Ecevit, Safiye Tuba M.S., The Department of Polymer Science and Technology Supervisor: Leyla Aras, Prof. Dr. Co- Supervisor: Teoman Tinç
er, Prof. Dr. March 2004, 44 pages The basic reseach on the surface sulfonation of the polypropylene is very important due to the surface design for higher functionalization. For this purpose, liquid-phase sulfonation of the polypropylene surfaces at various temperatures for different time periods were performed by concentrated sulphuric acid. The physical and chemical changes formed by the effect of the sulfonation on the polypropylene surfaces were determined by contact angle measurement, mechanical analysis, UV-Vis spectrometer, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM). The surface polarity and wetting properties of the samples were evaluated by contact angle measurement. It is seen that, sulfonation at low temperatures and short time periods improve these two properties of the polypropylene surfaces. Sulfonation at high temperatures and long time periods however, cause the partial breakdown of the polymer by degradation. Noticeable color change due to the degradation and carbonization of the polypropylene films sulfonated at high temperature and long time were supported by the UV-Vis spectra of the samples. Mechanical properties of sulfonated PP films were investigated. Consequently, after the sulfonation process the mechanical properties of the PP films showed a general trend of decrease with sulfonation time for a given temperature and a very fast decrease at high temperature of sulfonation. Thermal characteristics were found by differential scanning calorimeter (DSC). Thermal analysis revealed that sulfonated PP film samples displayed an additional endothermic peak. The physical effects of the sulfonation were examined by scanning electron microscopy (SEM) which showed a hexagonal hole formations due to the bursting of the air bubbles within the PP films by the effect sulfonation. The lamelae formations were also seen around these holes.

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24

Venkatesan, Sriram. "SURFACE TEXTURES FOR ENHANCED LUBRICATION: FABRICATION AND CHARACTERIZATION TECHNIQUES". Lexington, Ky. : [University of Kentucky Libraries], 2005. http://lib.uky.edu/ETD/ukymeen2005t00274/Venkatesan%5FThesis.pdf.

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Thesis (M.S.)--University of Kentucky, 2005.
Title from document title page (viewed on November 9, 2005). Document formatted into pages; contains viii, 85 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 83-84).

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25

Kalil, Richard Charles Jr. "Evaluation of Frictional Characteristics of Precision Machined Surfaces". Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5000.

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Precision surface finishes are used in a wide variety of applications. From bearing races and rolling elements to parallel slide ways, the frictional characteristics of these surfaces are critical to the performance of the products. Experimental trial and error has shown that certain surfaces outperform others in certain applications, but the specific surface characteristics that make this true have yet to be fully understood. The research goal was to develop an apparatus that can test the coefficient of rolling/sliding friction of different precision machined surfaces and to combine this data with topographic analysis of the surfaces to correlate specific 3-D parameters with the frictional performance of a surface. The sample treatments consisted of four different surface textures (hard-turned, ground, honed and isotropic finish) and four different relative surface speeds. By monitoring the torque in the sample-mounting shaft under lubricated conditions the coefficient of rolling/sliding friction of each surface was found. Utilizing white light interferometry measurement of the surfaces, a highly detailed map of each surface was obtained. Using different characteristic values of each machined surface (RMS roughness, asperity density, lay direction, etc.), the frictional behavior of the surfaces were compared to the surface characteristics yielding insight into the relationship between surface finish and friction in rolling/sliding contact. Friction coefficient was found to correlate most strongly with RMS roughness (Sq) and density of surface summits (Sds). These parameters govern mechanical interference of asperities and surface adhesion respectively. These findings suggest that friction coefficients of surfaces could be optimized through manipulation of three-dimensional surface parameters.

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26

Mutti, Paolo. "Surface acoustic waves for semiconductor characterization". Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357598.

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27

Yildirim, Ismail. "Surface Free Energy Characterization of Powders". Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27525.

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Microcalorimetric measurements and contact angle measurements were conducted to study the surface chemistry of powdered minerals. The contact angle measurements were conducted on both flat and powdered talc samples, and the results were used to determine the surface free energy components using Van Oss-Chaudhury-Good (OCG) equation. It was found that the surface hydrophobicity of talc increases with decreasing particle size. At the same time, both the Lifshitz-van der Waals (gSLW) and the Lewis acid-base (gSAB) components (and, hence, the total surface free energy (gS)) decrease with decreasing particle size. The increase in the surface hydrophobicity and the decrease in surface free energy (gS) can be attributed to preferential breakage of the mineral along the basal plane, resulting in the exposure of more basal plane surfaces to the aqueous phase. Heats of immersion measurements were conducted using a flow microcalorimeter on a number of powdered talc samples. The results were then used to calculate the contact angles using a rigorous thermodynamic relation. The measured heat of immersion values in water and calculated contact angles showed that the surface hydrophobicity of talc samples increase with decreasing particle size, which agrees with the direct contact angle measurements. A relationship between advancing water contact angle qa, and the heat of immersion (-DHi) and surface free energies was established. It was found that the value of -DHi decrease as qa increases. The microcalorimetric and direct contact angle measurements showed that acid-base interactions play a crucial role in the interaction between talc and liquid. Using the Van Oss-Chaudhury-Goodâ s surface free energy components model, various talc powders were characterized in terms of their acidic and basic properties. It was found that the magnitude of the Lewis electron donor, gS-, and the Lewis electron acceptor, gS+, components of surface free energy is directly related to the particle size. The gS- of talc surface increased with decreasing particle size, while the gS+ slightly decreased. It was also found that the Lewis electron-donor component on talc surface is much higher than the Lewis electron-acceptor component, suggesting that the basal surface of talc is basic. The heats of adsorption of butanol on various talc samples from n-heptane solution were also determined using a flow microcalorimeter. The heats of adsorption values were used to estimate % hydrophilicity and hydrophobicity and the areal ratios of the various talc samples. In addition, contact angle and heat of butanol adsorption measurements were conducted on a run-of-mine talc sample that has been ground to two different particle size fractions, i.e., d50=12.5 mm and d50=3.0 mm, respectively. The results were used to estimate the surface free energy components at the basal and edge surfaces of talc. It was found that the total surface free energy (gS) at the basal plane surface of talc is much lower than the total surface free energy at the edge surface. The results suggest also that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic. The results explain why the basicity of talc surface increases with decreasing particle size as shown in the contact angle and microcalorimetric measurements. Furthermore, the effects of the surface free energies of solids during separation from each other by flotation and selective flocculation were studied. In the present work, a kaolin clay sample from east Georgia was used for the beneficiation tests. First, the crude kaolin was subjected to flotation and selective flocculation experiments to remove discoloring impurities (i.e., anatase (TiO2) and iron oxides) and produce high-brightness clay with GE brightness higher than 90%. The results showed that a clay product with +90% brightness could be obtained with recoveries (or yields) higher than 80% using selective flocculation technique. It was also found that a proper control of surface hydrophobicity of anatase is crucially important for a successful flotation and selective flocculation process. Heats of immersion, heats of adsorption and contact angle measurements were conducted on pure anatase surface to determine the changes in the surface free energies as a function of the surfactant dosage (e.g. hydroxamate) used for the surface treatment. The results showed that the magnitude of the contact angle and, hence, the surface free energy and its components on anatase surface varies significantly with the amount of surfactant used for the surface treatment.
Ph. D.

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28

Kapetas, Leon. "Microbial controls on contaminant metal transport in porous media". Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5769.

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Metal contamination in groundwater aquifers poses risks to human health as well as other life forms. Previous laboratory experiments have demonstrated that bacteria found in geologic settings like aquifers are likely to adsorb metal contaminants and attenuate metal migration. However, as bacteria can also migrate through the groundwater aquifer a better understanding of the combined effect of these two processes is required. The aim of this laboratory study was to a) explore the affinity bacteria exhibit towards metals and porous media of varying composition, b) investigate the effect of mineral and solution composition on the bacterial filtration and c) use the combined data to predict the impact of microbes on metal mobility in porous media. Pantoea Agglomerans was used as a model bacterium while column materials consisted of quartz sand and iron-oxide coated sand (IOCS). Bacteria were characterised using potentiometric titrations to identify the type and concentration of sites present on their bacterial wall. Particular attention was paid to the effect of kinetics of proton and metal adsorption due to the variable contact times that solutions have with bacteria in columns. It was found that increasing the contact time between cell surfaces and protons during potentiometric titrations resulted in less reproducible results. This was due to the release of cell exudates under high pH conditions rather than cell death. Exudates were also found to adsorb protons. Moreover, zinc adsorption onto cell surfaces is higher after 60 to 90 minutes of contact time, while there is a decline in adsorption for longer contact times due to release of cell exudates in the solution. Stability constants for the adsorption of zinc onto cell surface sites, quartz and IOCS materials were determined through batch adsorption experiments, providing a mechanistic explanation of the adsorption process. Reactive transport models incorporating kinetics and surface complexation are developed to describe zinc movement through packed columns. Batch kinetic studies showed that significant Zn sorption to IOCS takes place gradually during the first two hours of contact time. Adsorption continues to take place at a slower rate for an additional 10 hours. This kinetic effect is manifested also during flow-through experiments (column dimensions: length 0.12 m, diameter 0.025 m) with a Darcian velocity 6.1·10-3 cm s-1, which is comparable to natural groundwater flow rates through sand porous media. A pseudo-second order kinetic adsorption model is combined with a numerical advection dispersion model for the first time to predict Zn transport. Model output results are of mixed quality as the model cannot successfully describe contaminant arrival time and breakthrough curve shape simultaneously. Moreover, a mechanistic surface complexation reactive transport model is capable of predicting Zn sorption under varying pH conditions demonstrating the versatility of mechanistic models. However, these models do not account for kinetics and therefore they are not intended to fit the dispersion of the contaminant due to kinetic effects of adsorption. Experiments in mixed zinc/cell systems demonstrate that transport through IOCS is dominated by the adsorption to the porous medium. This is consistent with the batch surface complexation predictions for the system. Adsorption to bacteria is reversible and zinc is stripped from the cells and redistributed onto the IOCS. Adsorption onto cells becomes significant and plays a role in mobile metal speciation only once the column is saturated with zinc.

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Hayashi, Fumitaka. "The characterization of TLR5 /". Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8330.

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30

Viswanathan, Kalpana. "Synthesis and Characterization of Novel Polymers for Functional and Stimuli Responsive Silicon Surfaces". Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27052.

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The synthesis of a variety of novel functionalized polymers using living polymerization techniques to achieve functional and stimuli responsive coatings on silica surfaces are described. Since microscopic features on a surface influence the overall wetting properties of the surface, a systematic investigation of the influence of polymer architecture on the microscopic characteristics of the modified surfaces was studied using silane-functionalized linear and novel star-branched polystyrene (PS). Star-branched modifiers provide functional and relatively well-defined model systems for probing surface properties compared to ill-defined highly branched systems and synthetically challenging dendrimers. Using these simple star-shaped macromolecules it was shown that the topographies of the polymer-modified surfaces were indeed influenced by the polymer architecture. A model explaining the observed surface features was proposed. A living polymerization strategy was also used to synthesize centrally functionalized amphiphilic triblock copolymers. The amphiphilic copolymers exhibited stimuli responsive changes in surface hydrophobicity. In spite of multiple solvent exposures, the copolymer films remained stable on the surface indicating that the observed changes in surface properties were due to selective solvent induced reversible rearrangement of the copolymer blocks. The chemical composition of the copolymers was tailored in order to tune the response time of the surface anchored polymer chains. Thus, the polymer coatings were used to reversibly change the surface polarities in an on-demand fashion and could find possible applications as smart adhesives, sensors and reusable membrane devices. In contrast to the afore-mentioned covalent modification approach, which often leads to permanent modification of surfaces, renewable surfaces exhibiting â universalâ adhesion properties were also obtained through non-covalent modification. By employing hydrogen bonding interactions between DNA bases, surfaces functionalized with adenine groups were found to reversibly associate with thymine-functionalized polymers. This study describing the solvato-reversible polymer coating was the first demonstration on silica surfaces. A systematic investigation of the influence of surface concentration of the multiple hydrogen bonding groups and their structure on the extent of polymer recognition by the modified surfaces is also discussed.
Ph. D.

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31

Webb, Lauren J. Gray Harry B. "Chemical characterization and charge carrier dynamics of crystalline silicon(111) surfaces modified with surface-bound organic functional groups /". Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-05262005-123044.

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32

Akhtar, Moeen. "Characterization of industrial foulants and designing antifouling surfaces". Thesis, KTH, Tillämpad fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-301965.

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Industries (food, beverage, petrochemical, etc.) normally use various gravitational separation echniques in their processes. Such separation processes often suffer from the deposition of undesirable material on the active surfaces of the process equipment, e.g. a high-speed separator or decanter, causing a slew of problems with the process or product quality. To restore operational efficiencies, additional cleaning steps using both water and chemicals are required, making the process more expensive and less environmentally friendly. Other than operating time and concentration of the process fluid there are several factors such as surface nature, surface roughness, type of material, surface charge, etc which influence the fouling deposition of surfaces. Fouling on the surfaces can grow following different mechanisms. The goal of this research work is to learn more about the nature of foulant interactions with stainless steel surfaces and eventually design some antifouling methodology. It is too difficult to study foulingfor all kinds of solutions and industries, so we tried to investigate the organic deposition in dairy and brewery industries by using lab-scale synthesized milk and beer solutions, For quantitative and statistical examination of these characteristics, several experimental approaches (FTIR, percent weight change, surface roughness, surface energy) were used. It was confirmed that fouling grows on the surfaces in a non-linear fashion irrespective of the time and concentration of the solution. The fouling of surfaces can be improved by producing more hydrophilic surfaces or by reducing surface roughness. Steric hindrance, electrostatic charge, and water barrier or hydration layer theories can be used to modify the surface nature and hence the fouling deposition. For antifouling purposes, PMMA (organic) and tungsten oxide (inorganic) coatings were employed. The PMMA was deposited using a dip-coating technique using (6%,10%, and 12%) PMMA solution, and the tungsten oxide coating was carried out by using a standard two electrode electrochemical system under different voltage (3.5V and 4.5V) and time (5min, 10 min, and 20 min) conditions. The coatings were characterized by using different techniques and their antifouling effects were studied in model milk and model beer solutions
Vid industriella processer (livsmedel, petrokemisk etc.) används ofta olika tekniker för separation med hjälp av gravitation. Sådana separationsprocesser drabbas ofta av oönskade beläggningar och påväxt på processutrustningens aktiva ytor så som t.ex. i en separator eller en dekanter, vilket orsakar problem med processen eller produktkvaliteten. För att återställa driftseffektivitet krävs särskilda rengöringssteg med både vatten och kemikalier vilket gör processen dyrare och mindre miljövänlig. Förutom drifttid och processvätskans sammansättning finns det flera faktorer såsom ytbeskaffenhet, ytjämnhet, materialtyp, ytladdning m.m. som påverkar mängden oönskade beläggningar på ytor. Föroreningarna på ytor kan tillväxa med olika mekanismer. Målet med detta forskningsarbete är att studera interaktionen mellan olika former av påväxt och ytan på rostfritt stål och senare utforma metoder för att förhindra bildandet av sådana oönskade beläggningar. Det är en stor utmaning att studera olika typer av påväxt för alla typer av flöden och industrier. I studien undersöktes organisk påväxt inom mejeri- och bryggeriindustrin genom att använda syntetiserade mjölk- och ölprodukter i laboratorieskala, för kvantitativa och statistiska undersökningar av dessa egenskaper. Flera olika experimentella metoder användes (FTIR, viktförändring, ytjämnhet, ytenergi). Det bekräftades att tillväxten på ytorna var olinjärt oavsett tid och lösningens koncentration. Bildandet och tillväxt av oönskade beläggningar kan minskas med hjälp av mera hydrofila ytor eller genom att minska ytans ojämnhet. Steriska hinder, elektrostatisk laddning och vattenbarriär eller hydratiseringsskal kan användas för att modifiera ytan och därmed fördröja bildandet av oönskade beläggningar. För att förhindra påväxt belades ytan med PMMA (organisk) och volframoxid (oorganisk). PMMA deponerades genom en doppbeläggningsteknik med användning av (6%, 10% och 12%) PMMA-lösning och volframoxidbeläggningen utfördes med ett elektrokemiskt tvåelektrodssystem med olika spänningar (3,5V och 4,5V) och tider (5min, 10min och 20min). Ytbeläggningarna karakteriserades genom att använda olika tekniker och deras förmåga att förhindra snabb påväxt studerades i modellösningar av mjölk och öl.

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33

Parikh, Harshal. "Reservoir characterization using experimental design and response surface methodology". Texas A&M University, 2003. http://hdl.handle.net/1969/480.

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Colebrook, Marjorie Helen. "Rheology and electro-acoustic characterization of laterite slurries". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2454.

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A systematic research study was carried out in order to characterize the rheology of concentrated slurries prepared from eight nickel laterites. The experiments were carried out using a rotational viscometer, and the behavior of the laterites was evaluated in terms of the apparent viscosity and yield stress obtained through flow curve modeling. An attempt was made to correlate the results obtained for the laterite samples with data obtained for model single mineral systems as well as for model mixed mineral systems. In combination with detailed mineralogical characterization of the laterite samples, all the rheological results allowed a rheology-based laterite classification system to be proposed. Accordingly, the laterite samples gave the following responses: the SAPSIL samples (high-quartz) generally producedl ow yield stress values, the SAPFE samples (high-iron) were characterized by intermediate to high yield stress values, while the SAP samples (saprolite) gave the highest yield stress values. Interestingly, these dominant rheological responses of laterites could actually be predicted based on rheological tests carried out on model mineral suspensions (particularly goethite and quartz). Since the rheology of fine mineral suspensions is largely determined by the surface properties (surface charge) of the particles, a series of electro-acoustic measurements were also performed on model minerals and laterite samples to analyze the surface charge characteristics of the tested samples. It was demonstrated that the current electro-acoustic theory developed for single mineral systems can readily be used for modeling the behavior of mixed mineral systems. The modeling and experimental data agreed exceptionally well when constituent minerals were of the same surface charge under given pH. Clear but rather small deviations between experiment and theory were observed under conditions when the minerals were oppositely charged. This observation strongly suggested that inter-particle aggregation was most likely responsible for the observed discrepancies. Overall, the results of this thesis show that laterite slurries exhibit a wide range of rheological responses due to highly variable mineralogy, differences in particle size distributions, and difference in the surface properties of the many constituent minerals. It also shows that the surface properties of the minerals relates to rheology.

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35

VISHNUBHATLA, SATISH CHANDRA. "EXPERIMENTAL CHARACTERIZATION OF INTERFACIAL BEHAVIOR OF AQUEOUS SURFACTANT SOLUTIONS". University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148263635.

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36

Jose, Robin. "Synthesis and characterization of novel amphiphiles". Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1296090121&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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37

Teston, Eliott. "Nanohybrides superparamagnétiques à luminescence persistante : conception et application au marquage cellulaire pour la vectorisation magnétique in vivo". Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB025/document.

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La thérapie cellulaire consiste à utiliser des cellules comme médicament injectable dans le but de favoriser la réparation d'un tissu ou d'un organe. Certaines cellules possèdent la propriété de stimuler la formation de nouveaux vaisseaux sanguins. Elles présentent un intérêt pour le développement d'un traitement des ischémies des membres inférieurs ou du myocarde. Déterminer le devenir de ces cellules après injection in vivo est important pour comprendre les mécanismes responsables de l'efficacité d'un tel traitement. Cependant, il est difficile à observer et très peu décrit dans la littérature. Quelques exemples d'utilisation de nanotechnologies sont rapportés pour suivre des cellules in vitro. Mais des facteurs limitant tels qu'une complexité de mise en oeuvre de ces techniques ou leur trop faible sensibilité rend difficile leur utilisation in vivo. Ce travail de thèse propose de décrire le développement de nanoparticules originales associant les modalités d'imagerie optique et d'IRM afin de marquer simplement des cellules ayant un potentiel thérapeutique. Les protocoles développés ont permis de vectoriser et suivre en temps réel ces cellules après injection chez la souris
Cell therapy aims to use cells as injectable medicines in order to enhance damaged organs or tissues repair. Some cells have the ability to promote new blood vessels growth. Therefore, they have an interest in revascularization of ischemic tissues and are potential candidates for cell therapy in peripheral ischemia or myocardial infarction. Being able to determine these cell's fates after in vivo injection is a major step to better understand the mechanisms of such treatments efficiency. However, following this phenomenon is challenging and rarely described in scientific litterature. Only some applications of nanotechnologies to follow labeled cells in vitro have been published. But limitations as implementation complexity or a low sensitivity prevent from using these techniques in vivo. This phD work describes the development of new hybrids nanoparticules associating optical and magnetic resonance imaging modalities in order to efficiently label cells that have a therapeutic potential. Developed protocols allowed us to follow magnetic cell vectorisation after injection in mice in real time

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Jin, Zhiyun. "Characterization of DNA probes on silicon surface". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ62940.pdf.

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Ahsan, T. "Surface characterization of the precipitated calcium carbonate". Thesis, Brunel University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374851.

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MARQUES, MARCOS ALEXANDRE. "CHARACTERIZATION OF SURFACE DEFECTS ROLLED STEEL PRODUCTS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4394@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
O estudo teve por objetivo investigar o mecanismo de formação de trincas superficiais na direção longitudinal de laminação em barras do aço 1538 DH adotado na fabricação de componentes para a indústria automobilística. Tem-se conseguido alguns avanços no entendimento dos mecanismos de trincamento de produtos laminados, porém tais avanços não permitem, até o presente momento, a eliminação total do problema, o que vem causando o sucateamento de um expressivo percentual de produtos siderúrgicos. No escopo deste trabalho chegou-se a características microestruturais do material que sugerem as causas do trincamento durante o processo de laminação e, para tal, realizou-se o mapeamento das trincas, análises por microscopia ótica, classificação das inclusões, caracterizações por microscopia eletrônica de varredura e EDS, difração de raios-X, ensaios de tração, ensaios de dureza e microdureza, bem como simulação de ciclos térmicos. Os resultados destas análises indicaram que a nucleação e posterior propagação das trincas podem estar relacionadas à presença de precipitados de segunda fase em regiões interdendríticas, o que causaria a fragilização do contorno de grão durante laminação a quente.
The purpose of this study was to investigate the cracking mechanism with regard to longitudinal surface cracks in rolled 1538 DH steel bars used for the automotive industry. Although some advances have been achieved concerning the understanding of the cracking mechanism, the problem is not yet totally eliminated and still causing the scraping of a significant percentage of steel products. In the course of this work it was possible to determine some microstructural characteristics of the material which may lead to cracking due to the rolling process. In this sense, it was necessary to carry out an experimental procedure that included crack mapping, optical microscopy, classification of the inclusions, scanning electron microscopy, EDS analysis, X- ray diffraction, tensile testing, hardness and microhardness evaluation as well as thermal cycle simulations. The results seem to suggest that the crack nucleation and crack propagation are related to the presence of interdendritic second phase particles which induce to grain boundary embrittlement during hot rolling.

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Sherrington, Ian. "The measurement and characterization of surface topography". Thesis, University of Central Lancashire, 1985. http://clok.uclan.ac.uk/22006/.

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The concept of surface topography is introduced and its relevance to the production and functional behaviour of engineering components is highlighted. Some aspects of the measurement and characterization of surface topography are reviewed. The strengths and weaknesses of particular techniques are identified. A system developed by the author which measures surface topography is described. It employs a stylus transducer and is designed to gather areal data from nominally flat surfaces using a multiple parallel traversing technique. The system is computer controlled and makes use of an original sampling technique known as 'sampling in space. ' This permits the use of signal averaging to control the level of ambient noise in the data and implementation of algorithms to reject transient noise spikes. An accurate specimen relocation device is included. The performance of this equipment is analysed and found to be better than that of other systems which use the conventional 'sampling in time' technique. The uses of two-dimensional spectral analysis in the characterization of areal measurements of surface topography are investigated. Computer software for calculating areal spectra is developed and used to evaluate the power spectra of measurements from surfaces produced by a wide variety of manufacturing processes. A technique which involves sampling power spectra to form 'surface signatures' is described. This is found to be an effective method of simplifying spectra in order to observe characteristic features. The distribution of variance within power spectra is examined. It is found that for many classes of surface a majority of variance is described by a relatively small proportion of the coefficients of the spectrum. Consequently a good approximation of a surface can be obtained by applying the inverse Fourier transformation to a small group of selected coefficients. A catalogue of Fourier coefficients for constructing numerical models in this way is presented.

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Iyer, Ananth. "Surface characterization of lignocellulosics for composite manufacture /". Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.

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He, Liangyu. "Optical surface characterization with the structure function". Thesis, The University of North Carolina at Charlotte, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3608294.

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It is important to characterize surface and transmitted wavefront errors in terms of the spatial content. The errors are typically analyzed in three spatial domains: figure, ripple (or mid-spatial frequency) and roughness. These errors can affect optical system performance. For example, mid-spatial frequency errors can lead to self-focusing and power loss in a high-power laser system. Currently, power spectral density (PSD) is used for the spatial content characterization in high-end optics, although there are potential pitfalls. For example, the low spatial content is removed before calculation, only a small fraction of surface data are used, and the results are sensitive to details like the windowing.

As an alternative, the structure function (SF) does not have such problems. It is the expectation of the squared height difference as a function of separation. The linear SF has been used in astronomy and captures data of all spatial frequencies. However, it does not capture anisotropy on the surface. The two-quadrant area SF introduced in this dissertation obviates this problem. It is computationally correct for any arbitrary aperture over all spatial content with anisotropic information.

This dissertation discusses some computational issues of the SF, which includes the calculation of the linear / area SF, sliding sampling method for large numbers of points within the aperture, analysis of periodic errors, and connection between the linear SF and area SF.

Moreover, the relationships between the SF and other surface characterization techniques (Zernike polynomials, autocorrelation function (ACF), PSD, and RMS gradient) have been investigated. It turns out that the linear SF of the sum of the Zernike terms only equals to the sum of the linear SF of each of the Zernike polynomials with different azimuthal frequencies. However, this theorem does not apply to the area SF.

For stationary surfaces, the SF contains similar information as ACF, but it provides better visualization. The SF is computationally correct for any arbitrary aperture shape without extra processing, while the PSD always needs additional mathematical processing. After connecting the SF to the RMS gradient, the SF slope at the origin has been evaluated.

Use of a SF to specify optical surfaces over the full range of spatial frequencies of interest implies the combination of data from instruments with substantially different lateral resolutions. This research shows the combination of data from a Fizeau and a coherence scanning interferometer (CSI) for various precision surfaces. The investigation includes the connection method of the coordinate systems between the Fizeau data and the CSI sub-aperture data, the convergence of the averaged SF of sub-aperture samples, the uncertainty analysis, and the effect of the instrument transfer function (ITF).

In addition, the SF was used to explore two typical noise contributions (electronic noise and air turbulence) in phase shifting interferometry. Based on dynamic measurements, the SF was used to analyze the spatial components of a diamond turned surface after the compensation machining.

In summary, the SF is a useful tool to specify and characterize the spatial content of optical surfaces and wavefronts.

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Cushman, Cody Vic. "Multi-Instrument Surface Characterization of Display Glass". BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7477.

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Flat panel displays (FPDs) are microfabricated devices that are often fabricated on specialized glass substrates known as display glass. The surface chemistry of the outer few nanometers of display glass can have an important influence on FPD performance and yield. Dsiplay glass surface characterization is difficult because (i) display glass surface composition varies significantly from its bulk composition; (ii) high-surface area forms of glass, such as fibers and powders, may not have the same surface composition as melt-formed planar surfaces, and (iii) the surface composition of display glass may be altered through exposure to chemical treatments commonly used during flat panel display production, including acids, bases, etchants, detergents, and plasmas. We have performed a detailed surface composition of Eagle XG®, a widely used commercial display glass substrate, using a range of surface analytical techniques including time-of-flight secondary ion mass spectrometry (ToF-SIMS), angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and low energy ion scattering (LEIS). The information from these techniques has given us a detailed understanding of the elemental surface composition and surface hydroxylation of Eagle XG® at length scales ranging from ca. 10 nm from the surface to the outermost atomic layer. These analyses reveal that the surface composition of Eagle XG® varies significantly from its bulk composition, having generally lower concentrations of Al, B, Mg, Ca, and Sr, and higher concentrations of Si. Treatment with an industrial alkaline detergent results in significant recovery of aluminum concentration at the Eagle XG® surface, while treatment with hydrochloric and hydrofluoric acid result in further depletion of Al, B, Mg, Ca, and Sr at the sample surface.We used ToF-SIMS to quantify surface hydroxyls at the sample surface of this material. The SiOH+/Si+ peak area ratio was a useful metric of surface hydroxylation. We studied the effects of adventitious surface contamination on the measurements by analyzing samples dosed with perdeuterated triacontane, a model alkane, prior to analysis. Thick triacontane overlayers suppressed the SiOH+ signal, indicating that this approach gives inaccurately low estimates of surface hydroxylation for samples with high degrees of surface contamination, and accurate measurements are only possible for very-clean surfaces. The number of of hydroxyls on Eagle XG® surfaces varied as the surfaces were exposed to different chemical treatments. HF- and HCl- treated surfaces had the highest degree of hydroxylation, while detergent-treated surfaces had the lowest.

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Raja, Mohan Anandu, i Niranjan Sutar. "Characterization of Sealing Surface for Static Seals". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263915.

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Leakages from seals are one of the important factors that are taken into consideration while designing any machining element. This is because leakages can affect the performance of any component and can also turn into a catastrophe. If looked into it, many parameters can be pointed out that can enhance leakages within the system, some of them may be pressure, temperature, clamping force and bolt distance etc. But the main parameter is the surface roughness, higher the roughness more the leakage and vice-versa. Thus, in this thesis an attempt has been made how the surface roughness can affect the performance of the sealing concept for metal bounded gasket with above four mentioned parameters. Also how leak proof surface can be defined using standard tribological parameters is the aim of this thesis. This report includes the results for methodologies implemented during the thesis and track down the leakages. The leaked surfaces were carefully studied and analyzed using different standards compared with the non leaked surfaces’ roughness parameters.
Läckagerisk från tätande förband är en av de viktigaste faktorerna som beaktas vid utformning av konstruktionsartiklar. Detta på grund av att konsekvenserna kan bli förödande. Det tätande förbandet påverkas av många olika parametrar såsom till exempel tryck, temperatur, klämkraft, skruvavstånd och val av packning. En viktig faktor är ytans beskaffenhet; Generellt läcker en grov yta och vågig yta mer än en fin och plan yta. Således har i denna avhandling ytans beskaffenhet studerats tillsammans med en packning av typen metallburen gummipackning för att påvisa täthetfunktionen som en funktion av tryck, temperatur, klämkraft och skruvavstånd. Denna rapport innehåller resultat och analys av olika standardmetoder för de ytor som ingick i utredningen.

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Mani, Saikumar. "Surface characterization of polyvinylidene fluoride (pvdf) in its application as an actuator". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1349.

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Jiang, Guilin. "Characterization, Functionalization and Applications of Alkyl Monolayers on Silicon Surfaces". BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1073.

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Investigations were performed on the stability, mechanism of formation and an application of alkyl monolayers chemomechanically prepared on silicon surfaces. A new method of surface modification, laser-activation modification of surfaces (LAMS), and multivariate analyses of time-of-flight secondary ion mass spectrometry (ToF-SIMS) images of LAMS spots were also reported. X-ray photoelectron spectroscopy (XPS) and other data show that alkyl monolayers prepared by scribing silicon under 1-iodoalkanes and 1-alkenes were stable over extended periods of time to air, water, a boiling acid and Al Ka X-rays. The stability is attributed to direct Si-C bonding in the monolayers. The observation that the oxygen signals gradually increased and the iodine signals gradually decreased, with both finally reaching plateaus is attributed to the oxidation of exposed silicon by scribing, and the hydrolysis of Si-I bonds, respectively. In alkyl monolayers prepared with 1-alcohols, the carbon signals decreased about 50% after two 1-h immersions in a boiling acid, suggesting unstable Si-O bonding. In the analogous experiment of grinding silicon with alkyl halides, the expected free-radical combination and disproportionation byproducts were observed. This observation provides evidence for the mechanism previously proposed for alkyl monolayer formation on silicon by chemomechanically scribing. Miniaturized sample supports for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were made on hydrophobic silicon or glass surfaces by scribing. With these sample supports, improved MALDI-MS signal intensities and reproducibilities were achieved for a test peptide, as expected. A new and promising method for surface modification, LAMS, was developed. XPS and ToF-SIMS analyses show that both silicon and germanium were effectively modified by LAMS with even quite inert compounds. This technique was also used to make miniaturized MALDI-MS sample supports. Compared to scribing, LAMS is faster and can be more precisely controlled. Multivariate analyses, automated expert spectral image analysis (AXSIA) and principal component analysis (PCA), were used in interpreting ToF-SIMS images of silicon surfaces modified with 1-alkenes by LAMS. Both analyses show that modified and unmodified areas are chemically different.

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Mendoza, Alvaro. "The synthesis and characterization of novel surfactants". Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1296090131&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Topp, Kathryn A. "Cationic oligomeric surfactants novel synthesis and characterization /". Connect to full text, 2006. http://hdl.handle.net/2123/1728.

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Thesis (Ph. D.)--School of Chemistry, Faculty of Science, University of Sydney, 2006.
Title from title screen (viewed 13 January 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Chemistry, Faculty of Science. Includes bibliographical references. Also available in print form.

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Mallett, Susan. "Characterization of T lymphocyte antigens". Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293461.

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