Dissertations / Theses: 'Adhesion resistance'

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Lougheed, Caroline. "Targeting focal adhesion signaling in cancer and acquired resistance to focal adhesion kinase inhibitors." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=94996.

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In cancer progression, the development of metastases is characteristic of late stage disease and makes treatment and cure more difficult. In order for metastasis to occur, cancer cells must gain motile and invasive phenotypes. As one of the keystone proteins involved in cell motility and invasion, Focal Adhesion Kinase (FAK) has emerged as a good therapeutic target for the inhibition of metastases via targeted drug design and small molecule inhibitors. Accordingly, a small molecule inhibitor has recently been developed against FAK activation and signaling. However, drug resistance is common among targeted therapies. Development and classification of drug resistant cells elucidated the possible mechanism behind FAK inhibitor resistance such that second-line therapy drugs can be designed to overcome or avoid resistance. The overall data presented herein support the role of FAK as an important drug target in cancer metastasis as well as provide insight and direction for future FAK inhibitor design. Dans la progression du cancer, le développement de métastases est caractéristique de la phase terminale et rend le traitement difficile. Afin que des métastases se dévelopment, les cellules cancéreuses doivent acquérir de la motilité ainsi qu'un phénotype invasif. Considéré come l'une des plus importantes protéines participant dans la motilité cellulaire, la prot éine Focal Adhesion Kinase (FAK) a émergé comme une bonne cible thérapeutique pour l'inhibition de métastases par la création de drogues ciblées et de petites molécules inhibitrices. Par conséquent, une molécule inhibitrice de l'activation de FAK et sa signalisation a été récemment développée. Cependant, J'ai demontré que la résistance est commune parmis ces drogues. Le dévelopement et la classification des clones de cellules résistantes ont permi d'élucider un mécanisme impiquant en partie une amplification de l'activité FAK; ce mécanisme permetter a de découvrir des analogues de deuxième génération pour surmonter ou éviter la résistance. L'ensemble de données présentées ci-dessous supportet le rôle de FAK comme une cible importante dans la prévention de métastases et exposent les futur directions pour contourner la résistance aux inhibiteurs de FAK.

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Ahlberg, Jesper, and Esbjörn Blomquist. "Online Identification of Running Resistance and Available Adhesion of Trains." Thesis, Linköpings universitet, Fordonssystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71301.

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Two important physical aspects that determine the performance of a running train are the total running resistance that acts on the whole train moving forward, and the available adhesion (utilizable wheel-rail-friction) for propulsion and breaking. Using the measured and available signals, online identification of the current running resistance and available adhesion and also prediction of future values for a distance ahead of the train, is desired. With the aim to enhance the precision of those calculations, this thesis investigates the potential of online identification and prediction utilizing the Extended Kalman Filter. The conclusions are that problems with observability and sensitivity arise, which result in a need for sophisticated methods to numerically derive the acceleration from the velocity signal. The smoothing spline approximation is shown to provide the best results for this numerical differentiation. Sensitivity and its need for high accuracy, especially in the acceleration signal, results in a demand of higher sample frequency. A desire for other profound ways of collecting further information, or to enhance the models, arises with possibilities of future work in the field. Två viktiga fysikaliska aspekter som bestämmer prestandan för ett tåg i drift är det totala gångmotståndet som verkar på hela tåget, samt den tillgängliga adhesionen (användbara hjul-räl-friktionen) för framdrivning och bromsning. Från de tillgängliga signalerna önskas identifiering, samt prediktering, av dessa två storheter, under drift. Med målet att förbättra precisionen av dessa skattningar undersöker detta examensarbete potentialen av skattning och prediktering av gångmotstånd och adhesion med hjälp av Extended KalmanFiltering. Slutsatsen är att problem med observerbarhet och känslighet uppstår, vilket resulterar i ett behov av sofistikerade metoder att numeriskt beräkna acceleration från en hastighetssignal. Metoden smoothing spline approximation visar sig ge de bästa resultaten för denna numeriska derivering. Känsligheten och dess medförda krav på hög precision, speciellt på accelerationssignalen, resulterar i ett behov av högre samplingsfrekvens. Ett behov av andra adekvata metoder att tillföra ytterligare information, eller att förbättra modellerna, ger upphov till möjliga framtida utredningar inom området.

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Munch, Sabine M. G. "Influence of interfacial adhesion on the fracture resistance of polymer multilayers." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445160.

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St, Croix Bradley D. "Impact of intercellular adhesion on cell cycle and resistance to anticancer agents." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35331.pdf.

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Ebert, Daniel Ray. "Superhydrophobic, Biomimetic Surfaces with High and Low Adhesion, Optical Transmittance, and Nanoscale Mechanical Wear Resistance." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1475516443008829.

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Nejmeh, Kassem. "Enhancing adhesion and Water Resistance in Clayey adhesives Mixtures : Strategies for Vertical and Horizontal Applications." Electronic Thesis or Diss., Université Gustave Eiffel, 2024. http://www.theses.fr/2024UEFL2012.

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Le matériau argileux est depuis longtemps privilégié dans la construction pour ses caractéristiques respectueuses de l'environnement. Les fines particules d'argile jouent un rôle crucial dans l'amélioration de la cohésion de ces matériaux. Cette recherche se concentre sur l'exploration de mélanges à base d'argile en tant que substituts potentiels aux adhésifs traditionnels pour carreaux utilisés sur des dalles de béton. L'objectif est de développer un matériau présentant une forte résistance à l'adhérence et maintenant son intégrité même lorsqu'il est immergé dans l'eau. Étant donné la nature poreuse du mélange d'argile, il est crucial de respecter des conditions de séchage spécifiques et des périodes d'immersion. La phase initiale de l'étude consiste à réaliser un test mécanique pour mesurer la contrainte d'adhérence du matériau avant et après immersion dans l'eau. Un échantillon de sol de référence sert de référence pour évaluer cette contrainte. Pour influencer les propriétés mécaniques, nous introduisons une quantité proportionnelle de polymères ou de fibres dans le sol de référence, dans le but de modifier ses propriétés de cohésion. La sélection de polymères ou de fibres est stratégique, dans le but d'induire des changements dans les propriétés mécaniques du matériau et sa résistance à l'eau. Dans la phase suivante, l'étude se concentre sur la compréhension du processus de séchage et de la cinétique d'imbibition après l'ajout de polymères. De plus, nous apportons des preuves que le choix du polymère affecte significativement la cinétique d'immersion et le degré d'absorption d'eau. L'approche de recherche se déroule en trois scénarios distincts : tout d'abord, nous renforçons la résistance du mortier en incorporant divers polymères et fibres ; deuxièmement, nous visons à empêcher l'absorption d'eau dans l'adhésif ; et enfin, nous nous efforçons de développer un adhésif réversible capable de retrouver sa résistance mécanique après avoir subi une perte due à l'immersion, uniquement grâce à un processus de séchage. De plus, nous concevons des stratégies spécifiques pour les différentes méthodes d'application, en abordant à la fois les applications verticales et horizontales Earthen material has long been favored in building construction for its eco-friendly characteristics. Fine clay particles play a crucial role in enhancing the cohesion of such materials. This research focuses on exploring clay-based mixtures as potential substitutes for traditional tile adhesives used on concrete slabs. The objective is to develop a material that exhibits strong adhesion resistance and maintains its integrity even when submerged in water. Considering the porous nature of the clay mixture, adherence to specific drying conditions and immersion periods becomes crucial.The initial stage of the investigation involves conducting a mechanical test to measure the adhesive stress of the material before and after water immersion. A reference soil sample serves as the baseline for evaluating this stress. To influence the mechanical properties, we introduce a proportional amount of polymers or fibers into the reference soil, aiming to alter its cohesive attributes. The selection of polymers or fibers is strategic, intended to induce changes in the material's mechanical properties and its resistance to water.In the subsequent phase, the study focuses on understanding the drying process and imbibition kinetics following the addition of polymers. Additionally, we provide evidence that the choice of polymer significantly affects the kinetics of immersion and the degree of water absorption.The research approach unfolds in three distinctive scenarios: firstly, we enhance the strength of the mortar by incorporating diverse polymers and fibers; secondly, we aim to impede water absorption into the adhesive; and finally, we endeavor to develop a reversible adhesive capable of reclaiming its mechanical strength after experiencing loss due to immersion, solely through a drying process. Moreover, we devise strategies specific to different application methods, addressing both vertical and horizontal applications

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Sun, Xiaowen. "An integrin-based mechanism for sensitizing melanomas to therapies." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/6506.

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Metastatic melanoma is unusually lethal with a ten year survival rate of less than 10%. Conventional DNA-damaging agents produce little improvement in patient survival. Vemurafenib (Zelboraf), a targeted therapeutic that inhibits the oncogenic BRAF demonstrates significant survival benefit. Unfortunately, it is now evident that there is both intrinsic and acquired resistance. Consequently, new strategies for sensitizing melanomas to vemurafenib are needed. Melanoma resistance to therapy is fueled in part by the integrins, the major cell surface adhesion receptors which are highly over-expressed in melanoma. Both integrin antagonists and agents that engage defective integrins increase the sensitivity of melanomas to chemotherapy. Our laboratory has identified a novel peptide, denoted vinculin activating peptide or VAP that targets integrins from within the cell and brings aberrant integrin function intact. VAP sensitizes melanoma to dacarbazine in vitro and in vivo. The effect VAP has on overcoming resistance to targeted therapies like vemurafenib, as well as the mechanism for its effects are not well understood. The goals of this project are to determine if VAP can be employed to improve sensitivity and/or overcome resistance to vemurafenib and to identify the cell surface target of VAP. Our results show that VAP not only improves melanoma sensitivity to vemurafenib but also decreases intrinsic resistance to this promising drug. In addition, we present evidence that β1 and β3 integrins are the target of VAP's effects. Since peptide-based therapies are not stable in the clinic, we explored another integrin binding partner, kindlin-2. We found that kindlin-2 is over expressed in resistant melanomas. The inhibition of kindlin-2 increases β1 integrin activation and decreases β3 integrin functions. Agents that bring aberrant β1 and β3 integrin function intact can be employed to improve sensitivity and overcome resistance to vemurafenib suggesting that combinatorial therapies that employ vemurafenib and integrin-based agents might be efficacious in combatting resistance in melanoma patients.

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Tan, Jiahong Brash John L. "Polyethylene oxide-containing block copolymers as surface modification additives in polyurethanes for protein and cell resistance /." *McMaster only, 2004.

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Klittich, Mena R. "Surface Interactions with Hierarchical Nanostructures: From Gecko Adhesion to Thermal Behavior." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1499440265902425.

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Nakanishi, Takao. "The synergistic role of ATP-dependent drug efflux pump and focal adhesion signaling pathways in vinorelbine resistance in lung cancer." Kyoto University, 2019. http://hdl.handle.net/2433/236608.

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Di, Martino Patrick. "Caracterisation de facteurs impliques dans l'adhesion aux cellules epitheliales intestinales de souches de klebsiella pneumoniae responsables d'infections nosocomiales." Clermont-Ferrand 1, 1996. http://www.theses.fr/1996CLF1MM04.

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Wang, Xisheng. "Mechanisms of IFN-gamma-mediated Resistance against Development of Toxoplasmic Encephalitis." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/30268.

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Toxoplasma gondii, an obligate intracellular protozoan parasite, establishes a latent, chronic infection by forming cysts preferentially in the brain after replication of tachyzoites in various organs during the acute stage of infection. Chronic infection with T. gondii is one of the most common parasitic diseases in humans. The immune system is required for maintaining the latency of chronic infection. Reactivation of infection can occur in immunocompromised individuals, such as AIDS patients, which results in the development of life-threatening toxoplasmic encephalitis (TE). IFN-gamma-dependent, cell mediated immune responses play an essential role in preventing the reactivation of chronic infection of T. gondii in the brain. In my dissertation study, we examined the mechanisms of IFN-gamma-mediated prevention of TE by using models of reactivation of chronic infection in BALB/c mice. This strain of mouse is genetically resistant to T. gondii infection and establishes a latent chronic infection as do immunocompetent humans, and therefore provides an excellet model for this purpose. Our laboratory previously demonstrated that both T cells and IFN-gamma-producing non-T cells are required for genetic resistance of BALB/c mice against development of TE. However, the function of T cells required for the resistance is still unclear. Therefore, in the present study, we examined whether IFN-gamma production or perforin-mediated cytotoxicity of T cells play an important role in their protective activity against TE. Immune T cells were obtained from infected IFN-gamma-knockout (IFN-g-/-), perforin-knockout (PO), and wild-type (WT) BALB/c mice, and transferred into infected, sulfadiazine-treated athymic nude mice which lack T cells but have IFN-gamma-producing non-T cells. Control nude mice that had not received any T cells developed severe TE due to reactivation of infection and died after discontinuation of sulfadiazine treatment. Animals that had received immune T cells from either PO or WT mice did not develop TE and survived. In contrast, nude mice that had received immune T cells from IFN-gamma-/- mice developed severe TE and died as early as control nude mice. T cells obtained from spleens of the animals that had received either PO or WT T cells both produced large amounts of IFN-gamma following stimulation with T. gondii antigens in vitro. In addition, the amounts of IFN-gamma mRNA expressed in the brains of PO T-cell recipients did not differ from those of WT T-cell recipients. These results indicate that IFN-gamma production, but not perforin-mediated cytotoxic activity, by T cells is required for prevention of TE in genetically resistant BALB/c mice. In our attempt to identify a T cell population(s) that produces IFN-gamma in the brain and plays an important role for prevention of TE, we analyzed T cell receptor (TCR) Vb chain usage in T cells expressing IFN-gamma in the brains of infected BALB/c mice. We found T cells bearing TCR V beta8 chain to be the most frequent IFN-g-producing population in the brains of infected animals. To examine the role of IFN-gamma production by this T cell population for prevention of TE, V beta8+ immune T cells purified from spleens of infected BALB/c and IFN-g-/- mice were transferred into infected, sulfadiazine-treated athymic nude mice. After discontinuation of sulfadiazine treatment, control nude mice that had not received any T cells and animals that had received Vb8+ T cells from IFN-g-/- mice all died due to reactivation of infection (TE). In contrast, animals that had received the cells from WT mice survived. These results indicate that IFN-gamma production by Vb8+ T cells in the absence of any other T cell population can prevent reactivation of infection. Thus, V beta8+ T cells play a crucial role in genetic resistance of BALB/c mice to TE through their production of IFN-gamma. When V beta8+ immune T cells were divided into CD4+ and CD8+ subsets, a potent protective activity was observed only in the CD8+ subset whereas a combination of both subsets provided greater protection than did the CD8+Vb8+ population alone. These results indicate that CD8+ subset of V beta8+ T cells is a major afferent limb of IFN-gamma-mediated resistance of BALB/c mice against TE, although the CD4+ subset of the T cell population works additively or synergistically with the CD8+V beta8+ population. T cells need to enter into the brains of infected mice to demonstrate their protective activity against TE. This migration is mediated, in part, by endothelial adhesion molecules. Since IFN-gamma is essential for preventing reactivation of chronic infection with this parasite in the brain, we examined whether this cytokine plays an important role in expression of lymphocyte and endothelial adhesion molecules and recruitment of T cells into the brain during chronic infection with T. gondii using IFN-g-/- and WT BALB/c mice. Although the number of cerebral vessels expressing intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) increased in both WT and IFN-g-/- mice following infection, there were more VCAM-1+ vessels in brains of infected WT than infected IFN-g-/- mice; in contrast, numbers of ICAM-1+ vessels did not differ between strains. We did not detect endothelial E-selectin, P-selectin, MAdCAM-1 or PNAd in any of the brains. Significantly fewer CD8+ T cells were recruited into brains of infected IFN-g-/- than WT mice. Treatment of infected IFN-g-/- mice with recombinant IFN-gamma restored the expression of VCAM-1 on their cerebral vessels and recruitment of CD8+ T cells into their brains, confirming an importance of this cytokine for up-regulation of VCAM-1 expression and CD8+ T cell trafficking. In infected WT and IFN-g-/- animals, almost all cerebral CD8+ T cells had an effector/memory phenotype (LFA-1high, CD44high and CD62Lneg) and approximately 38% were positive for a4b1 integrin (the ligand for VCAM-1). In adoptive transfer of immune spleen cells, pre-treatment of the cells with a monoclonal antibody against a4 integrin markedly inhibited recruitment of CD8+ T cells into the brain of chronically infected wild-type mice. These results indicate that IFN-g-induced expression of endothelial VCAM-1 and its binding to a4b1 integrin on CD8+ T cells is important for recruitment of the T cells into the brain during the chronic stage of T. gondii infection. Since we found strong expression of ICAM-1 on endothelia and LFA-1 on T cells in the brains of infected mice, LFA-1/ICAM-1 interaction, in addition to a4b1 integrin/VCAM-1 interaction, may also be involved in this process. As mentioned earlier, CD8+ T cells are crucial for prevention of TE in BALB/c mice. Therefore, IFN-gamma-mediated expression of VCAM-1 and its binding to a4b1 integrin for recruitment of CD8+ T cells may play a critical role in genetic resistance of BALB/c mice to development of TE. Ph. D.

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Chu, Calvin. "MCP-1 Induces Rapid Formation of Tethered VLA-4 Bonds with Increased Resistance to Applied Forcein THP-1 Cells." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/592.

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The chemokine, Monocyte Chemoattractant Protein (MCP-1), enhances integrin mediated monocyte adhesion to the vascular endothelium during inflammation. In this study, we demonstrate that MCP-1 promotes rapid sub-second adhesion of THP-1 cells to Vascular Cell Adhesion Molecule-1 (VCAM-1), but not to Intercellular Cell Adhesion Molecule-1 (ICAM-1). MCP-1 activates membrane tethered Very Late Antigen 4 (VLA-4, α4β1), but not necessarily cytoskeleton anchored VLA-4. Activated tethered VLA-4 bonds tremendously increased the period of time monocytes remain bound from hundreds of milliseconds to several seconds and also increased the distance over which immunologic surveillance occurs from several microns up to 20 microns along the endothelium. Lastly at the single molecule level, MCP-1 stimulated tethered VLA-4 bonds exhibit increased resistance to pulling force. In conclusion MCP-1 increased tethered VLA-4 bond resistance to force providing a mechanism for monocyte recruitment to the endothelium.

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Opp, Daniel. "Transendothelial Migration of Metastatic Cancer Under the Influence of Cigarette Smoke Condensate." Scholar Commons, 2007. http://scholarcommons.usf.edu/etd/3808.

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Cigarette smoke's influence on cancer has primarily been a subject of epidemilogic and tumorigenic studies. There have been no proper investigations with interests focused on how cigarette smoke affects the cellular mechanics of metastasis. Gathering an understanding of how smoke influences metastatic invasion could be vital in regulating or possibly eliminatings cancer's ability to initiate new tumor growth sites. This project focuses on cigarette smoke's influence on cellular mechanics of endothelial cells, and the invasive potential of cancer against a fully active endothelium. It is already known that cigarette smoke has a carcinogenic effect, but it is hypothesized that the cigarette smoke causes the endothelium to exhibit pro-invasive characteristics. Cancer cells are often ignorant to extra-cellular stimuli. It is suspected that there will be a less pronounced degradation of cellular mechanics of cancerous cells than endothelial cells when exposed to similar concentrations of cigarette smoke.

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Boban, Greg. "Tribological Comparison of Traditional and Advanced Firearm Coatings." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/361.

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The objective of this project is to find which type of coating has the best performance characteristics for finishing firearms. This is accomplished by measuring and comparing several performance characteristics, such as: adhesion, hardness, wear resistance, friction control, and corrosion resistance. Appearance is not a factor since any exterior coating that is flashy can be subdued or camouflaged with special purpose paints, which have proven durable enough for such purposes. Cost will not be a limiting factor for this experiment, but will be discussed in the conclusion as a secondary concern. This data will be used to identify the best coating for steel and aluminum firearm parts. The goal is to lengthen a firearm’s life cycle while increasing performance and reliability by applying the best coating.

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Forestier, Jean-Paul. "Caracterisation de l'interface composite de collage / attaches orthodontiques." Paris 7, 1997. http://www.theses.fr/1997PA07GA03.

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Adsero, Matthew E. "Impact of Jet Grouting on the Lateral Strength of Soil Surrounding Driven Pile Foundations." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/1378.

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Jet grouting was used to strengthen the soft soil surrounding the piles and the pile cap of two full-scale driven pile foundations. Soilcrete columns, created by jet grouting, were placed underneath the pile cap and surrounding the piles of the first foundation. Two rows of soilcrete columns were placed around the perimeter of one-side of the second. All of the jet grouting took place after construction of the pile caps. Laboratory testing of the soilcrete slurry showed the columns as having a design unconfined compressive strength of 550-650 psi, compared with the native soil strength of only 6-8 psi (850-1150 psf). Lateral loading of the pile foundation was then performed on these foundations. The results of this test were compared with a similar test performed on the same foundations under native soil conditions. The total lateral capacity of the pile foundation treated underneath the pile cap was increased by 500 kips, which equals an increase of 175%. The total lateral capacity of the pile foundation treated adjacent to the pile cap was 150%. Results of testing suggest that each of the jet-grout treated zones displaced as a rigid block. A majority of the increased lateral resistance came from the passive soil resistance acting on the face of the blocks and the adhesive soil resistance acting on the sides and bottom of the block as it displaced through the native soil. The remaining soil resistance, not accounted for by the passive and adhesive soil resistance, can potentially be attributed to increased soil pile interaction, which is predicted from the decrease in pile head rotation during loading following soil treatment.

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Avril, Florence. "Développement de nouvelles formulations polymères thermoplastiques pour l’élaboration de multi-matériaux sandwich acier / polymère / acier." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10324.

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L'objectif de notre travail de développer des multi-matériaux de type sandwich acier/polymère/acier destinés au secteur automobile en vue de l'allègement des structures. Ce nouveau matériau doit satisfaire plusieurs critères, à savoir: i) grande déformabilité à froid en vue de l'emboutissage, ii) tenue au fluage à haute température (T=200°C, étape de cataphorèse), iii) tenue en milieu agressif (chaud, humide, brouillard salin). De plus, l'adhésion polymère-métal doit être maîtrisée en vue d'éliminer les phénomènes de délamination lors de l'emboutissage des tôles. Ce sandwich doit être réalisable sur une ligne industrielle dont la température maximale de complexage est limitée à 200°C. Si une solution à chacun de ces points particuliers peut être facilement apportée, la réponse à l'ensemble de ces critères par une formulation unique est beaucoup plus complexe. Nous nous sommes focalisés sur une formulation permettant de répondre au critère de tenue au fluage pour des températures supérieures à 200°C mais dont l'adhésion à chaud sur le métal (étape de complexage sur la ligne industrielle) doit être à inférieure à cette même température de 200°C. Pour cela nous avons développé une formulation à base de polymères immiscibles polyamide 11/polyoléfine fonctionnalisée anhydride maléique compatibilisés in-situ. Nos travaux ont donc porté sur l'optimisation de cette formulation, via le contrôle de la morphologie en vue de l'élaboration d'un film ayant les caractéristiques d'un fluide polymère à contrainte seuil d'écoulement tout en ayant les propriétés d'adhésion adéquate The aim of this work is to develop multimaterials such as steel/polymer/steel composites for weight savings in automotive industry. To fully take advantage of properties of both steel and polymer materials, adhesion steel-polymer must be well controlled. Moreover, the composite must be compatible with processing on the industrial line and last not least, the structure must be flow resistant during the cataphoresis step (Painting process at 200°C for 30 minutes). This last condition is essential and our work will focuse on the development of compatibilized polymers blend made of polyamide 11 and polyolefin grafted maleic anhydride with yield stress properties. We successfully optimize the formulation via morphological control in order to develop a yield stress fluid with good adhesive properties

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Gomand, Faustine. "Bacterial abilities to adhere to food components : extent, characterisation, and sensitivity to shear stress." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0123.

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Les bactéries lactiques (LAB) ont suscité ces dernières années un intérêt accru en agroalimentaire du fait de leur potentiel probiotique, i.e. des potentiels bénéfices santé associés à leur consommation. Les interactions adhésives entre bactéries et composants alimentaires sont susceptibles de jouer un rôle-clé à la fois sur la protection et la répartition des bactéries au sein de l’aliment, impactant donc leur action probiotique. Les travaux réalisés au cours de cette thèse ont pour objectif une meilleure compréhension de ces interactions, afin d’optimiser la fonctionnalité d’aliments contenant des LAB. En effet, le comportement adhésif de la majorité des LAB, ainsi que l’effet des interactions adhésives sur la structuration de l’aliment, sont encore mal connus. En outre, certaines étapes de fabrication alimentaire, telles que l’atomisation, peuvent être génératrices de stress pour les bactéries et donc partiellement compromettre leur capacité à adhérer. Dans le cas où ces bactéries seraient intégrées au sein d’une matrice adhésive, il est également légitime de s’interroger sur les effets de cette adhésion sur la protection des bactéries vis-à-vis du stress infligé. Une méthode de criblage haut-débit a d’abord été développée dans l’objectif d’évaluer rapidement l’affinité adhésive d’une centaine de souches vis-à-vis d’une gamme de biomolécules d’intérêt. Cette méthode a ensuite été appliquée à une collection de 73 souches LAB et a permis de dégager des caractéristiques communes parmi les souches adhérentes, notamment en termes de spécificité d’adhésion. Deux études (expérimentale et théorique) ont été menées conjointement sur l’impact du stress de cisaillement sur la fonctionnalité et l’intégrité des chaînes bactériennes. Ces études suggèrent que la rupture de chaînes bactériennes induite par un stress mécanique serait un processus protecteur de la fonctionnalité bactérienne. Le modèle construit prédit une régiosélectivité des dommages infligés aux cellules bactériennes en chaînes, dont l’intensité dépendrait également de la longueur de chaîne. Appliqué aux interactions adhésives bactéries-particules dans une matrice alimentaire soumise au cisaillement, le modèle suggère un impact défavorable de cette adhésion sur les dommages infligés aux bactéries, d’autant plus important que les particules sont de grande taille. Ce travail pluridisciplinaire apporte ainsi plusieurs éléments-clé qui seront utiles lors la conception et production d’aliments fonctionnels optimisés par rapport à leur action probiotique In the last decade, there has been an increasing interest in the potential health effects associated with consumption of Lactic Acid Bacteria (LAB) in foods. Adhesive interactions between bacteria and food components are likely to play a key role on bacterial probiotic action by modulating both bacterial protection and distribution within food matrices. Research presented in this thesis aims a better understanding of these interactions to help optimizing functional food design. Indeed, the adhesive behavior of most LAB, as well as the impact of adhesive interactions on food structuration, remain mostly unknown. Furthermore, some food manufacturing steps, such as spray-drying, may induce stress on bacteria, which can cause partial loss of bacterial adhesive capacities. In case of bacteria integrated within an adhesive matrix, the effect of adhesive interactions on bacterial protection from stress can also be questioned. A high-throughput screening method was first designed to screen quickly a hundred of strains for their adhesive affinities towards a given range of biomolecules of interest. This method was then applied to a 73-LAB strains collection which allowed identifying common characteristics amongst adhesive strains, especially in terms of adhesion specificity. Two studies (experimental and theoretical) were performed in parallel to determine the impact of shear stress on bacterial functionality and bacterial chains integrity. These studies suggest that the stress-induced breaking-down process of bacterial chains can be thought of as a functionality protective process. The proposed model predicts regioselectivity of damages inflicted to bacterial cells within a chain, which intensity would vary with chain length. When applied to bacteria-spherical component adhesive interactions within a food matrix submitted to shearing, the model suggests an unfavorable impact of adhesion on bacterial cell damages, which would be all the more important than spheres are big. This multidisciplinary research project points out several key findings that may help with designing more efficient food matrices for optimized LAB delivery

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Neto, Jadir Rodrigues Fagundes. "Acompanhamento clínico-laboratorial da utilização de Enfuvirtida em pacientes HIV soropositivos multiexperimentados atendidos nos ambulatórios do Hospital Universitário Pedro Ernesto." Universidade do Estado do Rio de Janeiro, 2012. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=5973.

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A Enfuvirtida(ENF), único inibidor de fusão disponível, representa uma opção interessante aos pacientes com infecção pelo HIV quando utilizada em combinação com outros antirretrovirais, principalmente no tratamento de multiexperimentados com falha virológica e poucas opções terapêuticas. Sua eficácia já comprovada em ensaios clínicos esbarra nas barreiras impostas por sua administração parenteral. Impulsionado por estes dados, avaliamos durante 48 semanas a resposta virológica, a evolução de células T CD4 a possível resistência primária a ENF e o impacto para a adesão do uso subcutâneo da droga em dez pacientes que fazem acompanhamento ambulatorial no Hospital Universitário Pedro Ernesto e que tinham história de mais de dez anos de infecção pelo HIV e uso de ENF no seu esquema terapêutico sugerido por teste de resistência. Todos os pacientes alcançaram ao final do seguimento sucesso terapêutico, mantendo carga viral não detectada, e um incremento médio significativo de linfócitos T CD4. Em relação a uma possível resistência primária, em nenhum dos testes, genotipagem da glicoproteína 41, foi visualizado mutações naturais que pudessem diminuir a ação da ENF. Sobre o manejo do medicamento, preparo e aplicação, observamos que é imprescindível um apoio multidisciplinar para que não haja descontinuação na sua utilização Enfuvirtide (ENF) is the only fusion inhibitor available. It is an interesting option for patients with HIV infection when used in combination with other antiretroviral drugs, especially in the treatment of multi-experienced patients with virological failure and few therapeutic options. Its effectiveness confirmed in clinical trials finds the barriers in its parenteral administration. Using these data, we evaluated, for 48 weeks, the virological response, evolution of CD4 T cells, the possible primary resistance to ENF and the impact to the subcutaneous use of the drug in ten patients undergoing outpatient monitoring at Hospital Universitário Pedro Ernesto with a history of more than ten years of HIV infection and use of ENF in their therapy, as suggested by resistance testing. All patients have successfully completed the therapy by the end of follow-up with an undetected viral load and a significant average increase of CD4 T lymphocytes. As for a possible primary resistance, neither the genotyping nor the glycoprotein 41 revealed natural mutations that could diminish the effect of ENF. Concerning the management, preparation and application of the drug, we found that a multidisciplinary support is essential to avoid that the drug be discontinued

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Danoumbé, Bonaventure. "Étude de couches minces de cuivre sur substrat YIG en vue de réaliser des composants magnétiques passifs planaires pour un fonctionnement à haute température." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSES022/document.

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L’objectif des travaux menés au cours de cette thèse concerne l’étude et la réalisation de composants passifs planaires à couches magnétiques (YIG) fonctionnant à haute température (200°C). Pour cela, des études ont été effectuées en deux phases : une première partie sur la mécanique des empilements des couches minces et une seconde partie sur la caractérisation électrique des couches minces et des composants planaires réalisés (inductances planaires). La première phase a permis de mettre en évidence l’intégrité mécanique de la structure, c’est-à-dire une bonne adhésion des couches minces de cuivre sur le substrat magnétique (YIG) jusqu’à une température de 200°C. La deuxième phase sur la partie électrique des couches minces et des composants planaires a permis de mettre en évidence qu’aucune modification n’a été apportée à la structure du composant, et met en évidence que le composant garde ces mêmes propriétés électriques après un cyclage thermique (25°C – 200°C – 25°C) The objective of the works carried out during this thesis concerns the study and realization of planar passive components with magnetic layers (YIG) operating at high temperature (200 ° C). For this, studies were carried out in two phases: a first part on the mechanics of stacking thin films and a second part on the electrical characterization of thin films and planar components realized (planar inductances). The first phase made it possible to demonstrate the mechanical integrity of the structure, that is to say a good adhesion of the thin copper layers on the magnetic substrate (YIG) up to a temperature of 200 ° C. The second phase on the electrical part of the thin layers and the planar components made it possible to demonstrate that no modification has been made to the structure of the component and shows that the component retains these same electrical properties after cycling Thermal (25 ° C - 200 ° C - 25 ° C)

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22

Aleksandar, Miletić. "Razvoj nanoslojnih i nanokompozitnih metal-nitridnih prevlaka." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2015. http://www.cris.uns.ac.rs/record.jsf?recordId=95438&source=NDLTD&language=en.

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Razvijene su TiAlN/TiSiN i CrAlN/TiSiN nanoslojne prevlake u kojima je napravljen spoj nanoslojnog i nanokompozitnog dizajna. Akcenat je stavljen na proizvodnju prevlaka visoke tvrdoće i visoke otpornosti na lom. Proučavane su i jednoslojne TiAlN, nanokompozitne TiSiN i višeslojne TiAlN/TiSiN prevlake kako bi se utvrdilo kako dizajn utiče na osobine prevlaka. Sve prevlake pripremane su sa jednim, dva i tri stepena rotacije. Pokazano je da dizajn i vid rotacije značajno utiču na mikrostrukturu i teksturu prevlaka, a time na njihove mehaničke osobine, otpornost na lom, adheziju između prevlake i podloge, topografiju površine i tribološko ponašanje. Nanoslojne i nanokompozitne prevlake odlikuju se kompaktnom nanokristalnom mikrostrukturom, dok jednoslojne TiAlN prevlake imaju stubastu strukturu sa kristalnim zrnima veće veličine. Pri prelasku sa jednog na više stepeni rotacije mikrostruktura prevlaka postaje kompaktnija sa kristalnim zrnima manje veličine i manjom poroznošću. U skladu sa tim, najmanju hrapavost, najveću tvrdoću, najveću otpornost na lom i najveću otpornost na habanje imaju nanoslojne i nanokompozitne prevlake pripremane sa dva i tri stepena rotacije. With the aim to develop hard coatings characterized by both, high hardnessand high resistance to cracking, synergy between nanolayered andnanocomposite design was made and nanolayered TiAlN/TiSiN andCrAlN/TiSiN coatings were produced. Monolayer TiAlN, nanocompositeTiSiN and multilayer TiAlN/TiSiN were also studied in order to find therelation between the coating design and their properties. All coatings weredeposited with 1-fold, 2-fold and 3-fold rotation. It is shown that coatingdesign and type of rotation have great influence on coating microstructureand texture, and in this way on their mechanical properties, resistance tocracking, adhesion between coating and substrate, surface topography andtribological behavior. Nanolayered and nanocomposite coatings arecharacterized by compact nanocrystalline microstructure, while monolayerTiAlN coatings have columnar structure with larger crystalline grains. Byincreasing the number of rotational degrees from 1-fold to 3-fold size ofcrystalline grains decreases and microstructure becomes more dense.Therefore, nanolayered and nanocomposite coatings deposited with 2-foldand 3-fold rotation are characterized by the highest hardness, highestresistance to cracking, highest wear resistance and the smoothest surfacetopography.

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Korenberg, Capucine Florence. "The durability of adhesive joints." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272387.

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Palmer, S. "The mannose-resistant adhesion antigens of uropathogenic Escherichia coli." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380217.

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25

Saffiedine, Brahim. "Contribution à l'étude du système BAC "Biofilm Associated Cluster" chez Pseudomanas aeruginosa." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR018/document.

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Pseudomonas aeruginosa (PA) est une bactérie Gram négatif, pathogène opportuniste, impliquée dans un grand nombre d’infections nosocomiales. Cette bactérie est aussi le principal micro-organisme responsable des surinfections broncho-pulmonaires chez les patients atteints de mucoviscidose. Cette prééminence est due en partie à la capacité de PA à former des biofilms, ce qui lui confèrent une résistance exceptionnelle aux antimicrobiens. Au sein de notre laboratoire, une analyse protéomique différentielle a permis de démontrer, en 2004, l’existence d’un protéome spécifique lorsque la bactérie se développe en mode biofilm. Parmi les protéines spécifiquement exprimées en mode biofilm, la protéine hypothétique PA3731 a été plus particulièrement étudiée. Cette protéine est impliquée dans la formation de biofilm, la production de rhamnolipides, la résistance à la tobramycine et la mobilité de type « swarming ». Des recherches bioinformatiques ont montré que le gène pA3731 appartient à un cluster de 4 gènes allant de pA3729 à pA3732 (système BAC), qui pourraient être impliqués dans l’élaboration et/ou la régulation d’un même système protéique. Cette hypothèse a constitué le point de départ de ce travail de thèse. La présente étude a permis de confirmer l’implication du système BAC dans la formation du biofilm, la résistance aux antibiotiques et la production de rhamnolipides chez PA. Les études protéomiques ont mis en évidence l’implication de ce système dans l’expression de la pompe MexEF-OprN, de la porine OprD, et dans la régulation du Quorum Sensing. Des études intéractomiques, menées en parallèle, ont montré une forte interaction entre la protéine PA3731 et PA3732. Ces études ont également permis de valider une forte interaction entre ces protéines et les rhamnolipides. L’ensemble de ces résultats nous permettent d’avancer une hypothèse quant à l’implication du système BAC dans le transport des rhamnolipides vers le milieu extracellulaire Pseudomonas aeruginosa (PA) is a Gram-negative bacterium, opportunistic pathogen, involved in a large number of nosocomial infections. This microorganism is also the main infectious agent involved in bronchopulmonary infections in cystic fibrosis patients. This pre-eminence is partly due to the ability of PA to form biofilms, which confers to the bacterial cells an increased resistance to antibiotics. In our laboratory, a differential proteomic analysis allowed to demonstrate in 2004, the existence of a specific proteome when the bacterium grows in the biofilm mode. This study allowed identifying about 40 proteins, specifically accumulated when bacteria adhere to a surface. Among these proteins, the hypothetical protein PA3731 has been particularly investigated. This protein is involved in the biofilm formation, the rhamnolipids production, the resistance to tobramycin and the swarming mobility. Bioinformatic research showed that the pA3731 gene belongs to a cluster of 4 genes ranging from pA3729 to pA3732 (BAC system), which could be involved in the development and / or regulation of the same protein system. This hypothesis was the starting point of this thesis work. The present study confirmed the involvement of the BAC system in the biofilm formation, the antibiotic resistance and the rhamnolipid production in PA. Proteomic studies highlighted the implication of this system in the expression of the MexEF-OprN pump and that of the OprD porin, and in the regulation of Quorum Sensing. Interactomic investigations, conducted in parallel, showed a strong interaction between PA3731 and PA3732 proteins. These studies have also pointed out a strong interaction between these proteins and rhamnolipids. All these results suggest that the BAC system could play a major role in the transfer of rhamnolipids to the extracellular environment

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Pourrahimi, Amir Masoud. "The synthesis, surface modification and use of metal-oxide nanoparticles in polyethylene for ultra-low transmission-loss HVDC cable insulation materials." Doctoral thesis, KTH, Polymera material, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190808.

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Polyethylene composites which contain low concentrations of metal-oxide nanoparticles e.g. ZnO and MgO are emerging materials for the use in insulations of extruded high-voltage direct-current (HVDC) cables. The challenge in the development of the composites with ultra-low electrical conductivity is to synthesize uniform and high-purity metal-oxide nanoparticles, which are functionalized with hydrophobic groups in order to make them compatible with polyethylene. The thesis reports different approaches to prepare this new generation of insulation materials. Different reaction parameters/conditions – zinc salt precursor, precursor concentrations and reaction temperature – were varied in order to tailor the size and morphology of the ZnO nanoparticles. It was shown that different particle sizes and particle morphologies could be obtained by using different zinc salt precursors (acetate, nitrate, chloride or sulphate). It was shown that 60 °C was a suitable reaction temperature in order to yield particles with different morphologies ranging from nano-prisms to flower-shaped superstructures. For removal of reaction residuals from the particles surfaces, a novel cleaning method based on ultrasonication was developed, which was more efficient than traditional water-replacement cleaning. After cleaning, the presence of one atomic layer of zinc-hydroxy-salt complex (ZHS) on the nanoparticle surfaces was suggested by thermogravimetry and infrared spectroscopy. A method involving three steps – silane coating, heat treatment and silica layer etching – was used to remove the last trace of the ZHS species from the nanoparticle surface while preserving its clean and active hydroxylated surface. The surface chemistry of these nanoparticles was further tailored from hydroxyl groups to hydrophobic alkyl groups with different lengths by reactions involving methyltrimethoxysilane (C1), octyltriethoxysilane (C8) and octadecyltrimethoxysilane (C18). MgO nanoparticles were prepared by aqueous precipitation of Mg(OH)2 followed by a partial transformation to MgO nanoparticles via heat treatment at 400 °C. The surface regions of the MgO nanoparticles convert into a hydroxide phase in humid media. A novel method to obtain large surface area MgO nanoparticles with a remarkable inertness to humidity was also presented. The method involved three steps: (a) thermal decomposition of Mg(OH)2 at 400 °C; (b) silicone oxide coating of the nanoparticles to prevent inter-particle sintering and (c) a high temperature heat treatment at 1000 °C. These MgO nanoparticles showed essentially no sign of formed hydroxide phase even after extended exposure to humid air. The functionalized metal-oxide nanoparticles showed only a minor adsorption of phenolic antioxidant, which is important in order to obtain nanocomposites with an adequate long-term stability. Tensile testing and scanning electron microscopy revealed that the surface-modified metal-oxide nanoparticles showed improved dispersion and interfacial adhesion in the polyethylene matrix with reference to that of unmodified metal-oxide nanoparticles. The highly “efficient” interfacial surface area induced by these modified nanoparticles created the traps for charge carriers at the polymer/particle interface thus reducing the DC conductivity by more than 1 order of magnitude than that of the pristine polyethylene. Polyetenkompositer med mycket låga halter av ZnO och MgO metalloxid nanopartiklar är en växande kategori material för användning som isolering av extruderade kablar avsedda för likriktad högspänning. En utmaning i utvecklingen av dessa material kan relateras till den praktiska kompositframställningen, vilken innefattar framställning av högrena metalloxid nanopartiklar som ytmodifieras med hydrofoba molekylstrukturer för att möjliggöra blandning med den hydrofoba polyetenplasten. Denna avhandling behandlar olika metoder för att framställa denna generation av isoleringsmaterial. Vid syntesen av de rena nanopartiklarna krävdes optimering av ett antal olika reaktionsparametrar för att uppnå tillfredställande slutresultat i form av partikelstorlekar och partikelmorfologier. Dessa inkluderade val av zinksalt, zinksaltkoncentration vid utfällning, samt reaktionstemperatur vid framställningen. Experimenten avslöjade att olika partikelstorlekar och partikelmorfologier kunde framställas som endast korrelerat mot källan av zinkjonerna, och berodde av vilka motjoner som zinkatomerna haft i zinksaltet (acetat, nitrat, klorid eller sulfat). Optimering av reaktionstemperaturen visade att ca 60 °C utgjorde en lämplig start för utvärdering av synteserna, som resulterade i olika partikelmorfologier i form av pyramidformade nanopartiklar till blomformationer. Utöver de specifika reaktionsparametrarna utvecklades även en ny ultrasonikeringsmetod för att rena ytorna hos partiklarna från motjoner relaterade till de valda specifika salterna. Metodiken som visade sig avsevärt mer effektiv än sedvanlig rening att utfällda nanopartiklar via repetitivt vattenutbyte, och skapade förutsättningar etablering av kolloidal stabilitet och fragmentering av aggregat i vattensuspensionerna. Efter ultrasonikeringsreningen beräknades de kvarvarande zinkhydroxidsalterna (ZHS) utgöra endast ett atomlager ZHS utifrån termogravimetriska data kompletterade med infraröd spektroskopi. En metod att eliminera de kvarvarande ZHS-komplexen från ytan av partiklarna tillämpades/utvecklades, inkluderade ytbeläggning av partiklarna med silan, följt av värmebehandling samt etsning av den resulterande kiseloxidytan, för att uppnå en ren hydroxylyta på partiklarna. Ytkemin hos dessa partiklar modifierades från att bestå av hydroxylgrupper till att utgöras av hydrofoba alkylgrupper med olika längder relaterade metyltrimetoxysilan (C1), oktyltrietoxysilan (C8), eller oktadekyltrimetoxysilan (C18). Även MgO nanopartiklar framställdes via vattenutfällning av Mg(OH)2 partiklar, vilka omvandlades till MgO nanopartiklar via en lågtemperatur värmebehandling vid 400°C. Ytan av dessa partiklar omvandlades dock till hydroxid i fuktig miljö. En ny metod att bibehålla den stora ytarean av MgO nanopartiklarna med anmärkningsvärd motståndskraft mot att omvandlas till hydroxid utvecklades således. Metoden består av (a) en låg temperatur omvandling av Mg(OH)2, (b) en kiseloxidytbehandling av nanopartiklarna för att undvika partikelsintring vid högre temperaturer och (c) en hög temperaturbehandling vid 1000 °C. De framställda partiklarna uppvisade ingen anmärkningsvärd känslighet mot luftfuktighet och bibehöll MgO sammansättningen efter exponering mot fukt. De modifierade metalloxid nanopartiklarna visade mycket liten adsorption av fenoliska antioxidanter, vilket medförde en långtidsstabilitet hos polyeten nanokompositerna. De ytmodifierade metalloxidpartiklarna visade även förbättrade möjligheter för dispergering och yt-kompatibilitet med/i polyetenmatrisen i jämförelse med omodifierade metalloxidpartiklar, utifrån mätningar baserade på dragprovning och svepelektronmikroskopi. Slutligen, de utvecklade ytorna på de modifierade nanopartiklarna skapade ett polymer/nanopartikel gränssnitt som kunder fungera som laddningsansamlingsområden i nanokompositerna, vilket resulterade i en storleksordning minskad ledningsförmåga hos kompositerna jämfört med den rena polyetenen. QC 20160829

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Renza, Jaroslav. "Jízdní dynamika traktoru." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241322.

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This thesis analyses driving dynamics of tractors and its dependence on their weight and age. In the beginning, brief history of tractor development and definition of basic concept of the tractor analysis is described. The thesis states procedures for obtaining magnitudes necessary for determining of driving dynamics. Experimental part describes the realized measurement on chosen sample of tractors and interprets measured values. Last part of the thesis contains evaluation of the measurement results.

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28

Gomand, Faustine. "Bacterial abilities to adhere to food components : extent, characterisation, and sensitivity to shear stress." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0123.

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Les bactéries lactiques (LAB) ont suscité ces dernières années un intérêt accru en agroalimentaire du fait de leur potentiel probiotique, i.e. des potentiels bénéfices santé associés à leur consommation. Les interactions adhésives entre bactéries et composants alimentaires sont susceptibles de jouer un rôle-clé à la fois sur la protection et la répartition des bactéries au sein de l’aliment, impactant donc leur action probiotique. Les travaux réalisés au cours de cette thèse ont pour objectif une meilleure compréhension de ces interactions, afin d’optimiser la fonctionnalité d’aliments contenant des LAB. En effet, le comportement adhésif de la majorité des LAB, ainsi que l’effet des interactions adhésives sur la structuration de l’aliment, sont encore mal connus. En outre, certaines étapes de fabrication alimentaire, telles que l’atomisation, peuvent être génératrices de stress pour les bactéries et donc partiellement compromettre leur capacité à adhérer. Dans le cas où ces bactéries seraient intégrées au sein d’une matrice adhésive, il est également légitime de s’interroger sur les effets de cette adhésion sur la protection des bactéries vis-à-vis du stress infligé. Une méthode de criblage haut-débit a d’abord été développée dans l’objectif d’évaluer rapidement l’affinité adhésive d’une centaine de souches vis-à-vis d’une gamme de biomolécules d’intérêt. Cette méthode a ensuite été appliquée à une collection de 73 souches LAB et a permis de dégager des caractéristiques communes parmi les souches adhérentes, notamment en termes de spécificité d’adhésion. Deux études (expérimentale et théorique) ont été menées conjointement sur l’impact du stress de cisaillement sur la fonctionnalité et l’intégrité des chaînes bactériennes. Ces études suggèrent que la rupture de chaînes bactériennes induite par un stress mécanique serait un processus protecteur de la fonctionnalité bactérienne. Le modèle construit prédit une régiosélectivité des dommages infligés aux cellules bactériennes en chaînes, dont l’intensité dépendrait également de la longueur de chaîne. Appliqué aux interactions adhésives bactéries-particules dans une matrice alimentaire soumise au cisaillement, le modèle suggère un impact défavorable de cette adhésion sur les dommages infligés aux bactéries, d’autant plus important que les particules sont de grande taille. Ce travail pluridisciplinaire apporte ainsi plusieurs éléments-clé qui seront utiles lors la conception et production d’aliments fonctionnels optimisés par rapport à leur action probiotique In the last decade, there has been an increasing interest in the potential health effects associated with consumption of Lactic Acid Bacteria (LAB) in foods. Adhesive interactions between bacteria and food components are likely to play a key role on bacterial probiotic action by modulating both bacterial protection and distribution within food matrices. Research presented in this thesis aims a better understanding of these interactions to help optimizing functional food design. Indeed, the adhesive behavior of most LAB, as well as the impact of adhesive interactions on food structuration, remain mostly unknown. Furthermore, some food manufacturing steps, such as spray-drying, may induce stress on bacteria, which can cause partial loss of bacterial adhesive capacities. In case of bacteria integrated within an adhesive matrix, the effect of adhesive interactions on bacterial protection from stress can also be questioned. A high-throughput screening method was first designed to screen quickly a hundred of strains for their adhesive affinities towards a given range of biomolecules of interest. This method was then applied to a 73-LAB strains collection which allowed identifying common characteristics amongst adhesive strains, especially in terms of adhesion specificity. Two studies (experimental and theoretical) were performed in parallel to determine the impact of shear stress on bacterial functionality and bacterial chains integrity. These studies suggest that the stress-induced breaking-down process of bacterial chains can be thought of as a functionality protective process. The proposed model predicts regioselectivity of damages inflicted to bacterial cells within a chain, which intensity would vary with chain length. When applied to bacteria-spherical component adhesive interactions within a food matrix submitted to shearing, the model suggests an unfavorable impact of adhesion on bacterial cell damages, which would be all the more important than spheres are big. This multidisciplinary research project points out several key findings that may help with designing more efficient food matrices for optimized LAB delivery

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29

Stodolovská, Šárka. "Vývoj nového chemicky odolného nátěrového systému s obsahem druhotných surovin." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-432472.

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New types of highly chemically resistant coating systems, primarily designed for concrete and metal substrates are designed and experimentally verified within the diploma thesis. Secondary raw materials, including solidified hazardous waste, are used as microfillers. The developed coating system is solved in two quality levels – PREMIUM and ECOLOGY. The level of PREMIUM is mainly designed for environments where extreme chemical stress is occurring. The polymer coating systém ECOLOGY can be used in environments where aggressive chemical media also act, however the ecological foot of the input raw materials is most important. The diploma thesis is dealing with current issues in the practice and it is the part of the research project.

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Seják, František. "Vývoj speciálních ochranných hmot pro hygienicky čisté provozy." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265641.

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The diploma thesis deals with the development of special protective materials for hygienically clean plants. The main aim of the thesis is to develop a special protective material on a polymer base usable for hygienically clean industrial plants in two quality levels (economy and premium). The first of the developed polymer protective materials is physiologically harmless (economy) – suitable for contact with eatables. Second, premium material is antibacterial, especially suitable as a floor coating in hospitals, kitchens, sanitary facilities, schools and kindergarten etc. A partial aim is the replacement currently used primary raw materials as fillers by suitable secondary raw material.

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Li, Weihong. "Adhesive Applied Roofing System Resistance Evaluation and its Quantification." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28711.

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Adhesive Applied Roofing System (AARS) is a new generation of built-up roof, gaining popularity in the North American low-slope roofing market. All components of AARS are integrated using adhesives. Wind flow creates suction over a low-slope roof, which exerts uplift forces on the roof system. The components of AARS are subjected to the combined action of tensile and shearing forces due to the dynamic wind uplift action. As part of a research project, to quantify the wind performance of AARS, three different test methods, namely, pullout (to simulate the tensile force), peel (to simulate the shear force), and wind uplift tests were developed by Current (2009), Wu (2008) and Murty (2010), respectively. Three test methods have been submitted to standard development organizations for industrial applications. The present study proposes a correlation among these three different test methods, namely, "Higher resistance in both peel and pullout tests will result in the same or higher wind uplift resistance". The present proposal is being verified through experimental study. For four different scenarios, two set of samples were constructed by varying only one component between the samples. For each sample, more than eight specimens were tested in all three test methods. Data from peel, pullout and wind uplift test methods were compared and it successfully verified the present hypothesis. It is concluded that the test results obtained from the small-scale pullout and peel experiments can be used to predict the effectiveness of full-scale system behaviour. This finding is very useful to assess the wind uplift performance of AARS that are already in service. It is also applicable to the situation where the component substitution for AARS is needed at the construction site. To help the industrial partners, a portable tester was designed such that it can be used for pullout and peel tests in the field. The design specifications of the portable tester were extracted from the requirements of the pullout and peel test methods based on the laboratory tests. The tester was manufactured by SAI Design Inc. First, the functionality of the portable tester was verified by testing the resistance of roofing fasteners. To further validate the portable tester, more than two hundred AARS specimens of different configurations were constructed and tested by using both the portable tester and Instron machine. The test results and observed failure modes were compared. The data confirmed that the portable tester is a useful and valid equipment in performing both the pullout and peel tests. The device can be used in the field for the evaluation of system response under wind action. Thus it will be useful in quantifying the impact of environmental conditions on the AARS specimens and to examine the effects of component substitutions.

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GONCALVES, ROBERTA AMORIM DE MAGALHAES MONTEIRO. "FRACTURE RESISTANCE EVALUATION OF ADHESIVE INTERFACES IN DENTAL RESTORATIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=23159@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO O sistema adesivo desempenha um papel importante na restauração dental, uma vez que é o responsável por promover a adesão entre o dente e resina. Apesar do avanço deste material, ele ainda pode apresentar problemas quando atua no tratamento restaurador. Sob ação das cargas de mastigação, os possíveis defeitos presentes na interface adesiva podem atuar como concentradores de tensão. Na presença destas descontinuidades, a interface pode comportar-se de maneira frágil, fraturando abruptamente e comprometer a restauração. Quando essa interface não tem muita resistência à fratura, é caracterizada por baixos valores de tenacidade à fratura, KIc. Portanto, o objetivo do presente estudo foi avaliar, por um método alternativo de testes, a tenacidade à fratura da interface dente / restauração utilizando diferentes sistemas adesivos e resinas compostas. Os terceiros molares foram cortados e restaurados com um entalhe pré-existente. De acordo com o material de restauração (adesivos convencional ou autocondicionante; e resinas compostas híbrida ou nanohíbrida), foram divididos em três grupos. A resistência à fratura foi avaliada por meio de testes de KIc, usando corpos de prova nos quais a zona de processo (região da trinca) é similar à interface de restauração. Após o teste, as superfícies de fratura foram analisadas por microscopia óptica (lupa) e microscopia eletrônica de varredura (MEV) para observar os planos de propagação das trincas nesses ensaios de tenacidade. Análise dos testes mostrou que todos os grupos comportaram-se de maneira semelhante (ruptura frágil), o que foi confirmado pelas análises de superfície. A análise estatística dos valores de KIc para cada grupo indicou haver diferença entre os grupos comparados. Juntamente com a análise qualitativa da média e do desvio padrão, é possível concluir que o material utilizado no Grupo 3 teve um desempenho superior aos outros. The adhesive system plays an important role in dental restoration, since it is responsible for promoting adhesion between the tooth and the composite resin. Despite the advance of this material, it can still present problems when acting in restorative treatment. Under masticatory loads, the possible flaws present in the adhesive interface can act as stress raisers. In the presence of these discontinuities, the interface can behave fragile, fracturing abruptly and compromising the restoration. When this interface has not much resistance to fracture, is characterized by low values of fracture toughness, KIc. Therefore, the aim of the present study was to evaluate, by an alternative method of testing, the fracture toughness of tooth / restoration interface with different adhesive systems and composite resins. Third molars were cut and restored with a pre-existing crack. According to the restorative material (conventional adhesive or self-etching adhesive, and hybrid or nanohybrid composites), they were divided into three groups. The fracture toughness was measured by KIc testing, using specimens in which the process zone (crack region) is similar to restoration‟s interface. After testing, the fracture surfaces were analyzed by optical microscopy (magnifying glass) and scanning electron microscopy (SEM) to observe the propagation of cracks plans. Analysis of the tests showed that all groups behaved similarly (brittle fracture), which was confirmed by surface analyzes. Statistical analysis of the KIc values for each group indicated difference between the compared groups. With the statistical evaluation and a qualitative analysis of the means and standard deviation was possible to conclude the material used in Group 3 had a better performance than the other groups.

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Roche, Soline. "Propriétés viscoélastiques et plastiques par nano-indentation de couches minces polymères solides : étude en température et en pression." Ecully, Ecole centrale de Lyon, 2004. http://www.theses.fr/2004ECDL0013.

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Le sujet de cette étude porte sur la caractérisation mécanique en nanoindentation et nanorayure de couches minces polymères. L'objectif est d'améliorer la compréhension du comportement élastique d'un film mince polymère déposé sur un substrat dur. Des essais de nanoindentation et nanorayure sont réalisés sur des couches minces déposées sur différents substrats. Un modèle rhéologique est utilisé afin d'extraire les propriétés élastiques du film seul à partir de la réponse mesurée, correspondant au système {film+substrat}. Un phénomène caractéristique des couches minces polymères est mis en évidence : I'effet enclume. En indentation, il s'exprime de deux façons différentes : une augmentation du module de conservation du film avec la dureté, liée au durcissement du film et une diminution du facteur de perte du film avec la dureté, qui s'explique par I'augmentation de la température de transition vitreuse. En rayure, cet effet se manifeste par une augmentation des propriétés mécaniques du film. Au cours de cette étude, la présence de contraintes résiduelles, majoritairement d'origine thermique, est mise en évidence. Une méthode de détermination des contraintes résiduelles d'un film mince polymère est présentée Une interprétation de l’effet enclume est proposé. Celui-ci correspond à la mise en pression d'un film mince confiné entre I'indenteur en diamant et le substrat dur. Ses propriétés mécaniques augmentent avec la pression hydrostatique. Ce phénomène est d'autant plus sensible pour des films de faible épaisseur (<50 µm) dont les propriétés mécaniques sont nettement inférieures à celles du substrat Une étude en température montre que les courbes isothermes du module de conservation en fonction de la pression, sont décalées. L'effet enclume peut alors être décrit par une courbe unique, en appliquant les constantes additives déterminée pour une température de référence donnée. Il en est de même pour le facteur de perte du film. Enfin, les conséquences de I' effet enclume sur les propriétés d'usage des revêtements polymères sont étudiées : la résistance à la rayure et I'adhérence sur le substrat. Une application fondamentale des couches minces est étudiée : les revêtements multicouches. Il semble que I'effet enclume soit un phénomène à considérer afin d'améliorer la résistance à la rayure d'un revêtement mono ou multicouche. Les résultats obtenus sur les couches minces permettent de choisir deux formulations, de type topcoat et basecoat, afin de former un revêtement bicouche performant. Nous avons montré que la présence d'un primaire d'adhérence mou entre un topcoat et un substrat dur permet d'améliorer la performance à la rayure du revêtement final The topic of this study was to mechanically characterize in nanoindentation and nanoscratch thin polymers layers. The goal is to improve the understanding of thin polymer layer elastic behavior laid on hard substrate. Tests in nanoindentation and nanoscratch were done on thin polymer films laid on different substrates. A rheologic model was used in order to extract the film elastic properties from the measured value linked to {film+substrate}. A specific behavior of thin polymer film has been identified: the anvil effect. In indentation, it is observed in two different ways : increase of the conservation film modulus with the hardness, linked to the film hardening, and decrease of the loss tangent with the hardness, which is explained by increasing the vitreous transition temperature. In scratch test, this effect is related to the increase of the film mechanical properties. Nanoindentation tests have highlighted residual stresses, mainly thermal driven. A new methodology to characterize those residual stresses for a thin polymer film was presented. An interpretation of the anvil effect is proposed. This effect is linked to thin layer pressurized, confined between diamond indenter and hard substrate. Its mechanical properties grow with hydrostatic pressure. This phenomenon is greater for thin layers (< 50μm) with lower mechanical properties than those of the substrate. A logarithmic type evolution law is proposed. A temperature study show isothermal curves of the conservation modulus with the pressure are shifted. The anvil effect can be described by a unic curve, applying additive constants determined at a given reference temperature. It is the same for the film loss tangent. Moreover, the consequences of the anvil effect on the use properties of polymer coating are analyzed: scratch resistance and the adhesion to substrate. A fundamental application of thin film was studied multilayer coatings. It seems that anvil effect is a phenomenon to consider for improvement of mono or multilayer coating scratch resistance. The results obtained on thin layers allow to choose two mix of basecoat and topcoat in order to have an improved bilayer. We have demonstrated that a basecoat between the topcoat and the hard substrate allow an improved scratch resistance of the final coating

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Benyahia, Lazhar. "Relations entre les propriétés rhéologiques et physico-chimiques des polymères et leurs propriétés adhésives : application à la peau." Université Joseph Fourier (Grenoble ; 1971-2015), 1996. http://www.theses.fr/1996GRE10061.

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Les travaux de cette thèse répondent à une motivation fondamentale, dans la mesure où on essaie d'établir une corrélation entre le pouvoir adhésif des polymères et leurs propriétés rhéologiques, physico-chimiques, et a un besoin industriel d'autre part, puisque nous avons étudié une application originale : le pelage sur la peau humaine de bandes adhésives pharmaceutiques. Deux familles d'adhésifs, à base de copolymères à blocs styreniques, et à base d'acryliques éventuellement réticules, sont enduits sur des supports de polyester. Ces bandes adhésives sont appliquées sur des substrats rigides (verre, acier, plexiglas), préalablement traités selon un protocole adapté. Une machine de pelage spécifique conçue au laboratoire, permet de maintenir le front de pelage fixe, et d'en faciliter l'observation. Elle fonctionne dans une enceinte à température et humidité contrôlées. Les mesures de la force de pelage, de la vitesse de pelage, et la visualisation détaillée du front de décollement sont effectuées simultanément. Ainsi les différents mécanismes d'écoulement dans la zone de décollement ont été identifiés en relation avec les courbes maitresses de pelage cohésif ou adhésif dans une large gamme de vitesses et de températures. L'influence de la rugosité, du substrat, de la réticulation du polymère, de l'humidité de l'atmosphère, ont été mis en évidence. Par ailleurs, la caractérisation aréométrique des adhésifs a été faite en cisaillement dynamique et en élongation uniaxiale. La physico-chimie du problème a aussi été prise en compte, et nous avons déterminé les énergies de surface des adhésifs et substrats. A la lumière des essais de visualisation qui montrent la prédominance des effets elongationnels au niveau du front de pelage, et des observations optiques du dos du support qui ont permis de constater que l'énergie est principalement dépensée dans les cordages ou filaments, nous avons proposé une corrélation de l'énergie de pelage avec les effets elongationnels. Enfin, nous proposons une relation plus générale entre l'énergie de pelage et les différents paramètres rhéologiques et physico-chimiques sous une forme adimensionnelle. En outre, la condition de transition de la rupture cohésive a la rupture adhésive est présentée sous la forme d'une loi adimensionnelle. Enfin, une application originale du pelage de bandes adhésives sur la peau humaine est présentée

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Fisher, Gary Anthony. "The optimisation of bondcoat oxides for improved thermal barrier coating adhesion." Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245488.

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Perrinet, Olivier. "Analyse de l'endurance de contacts électriques Sn, Au et Ag soumis à des sollicitations complexes de fretting usure." Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0009.

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Dans les applications automobiles et dans d'autres domaines (énergie, aviation, etc), le nombre d'appareils électroniques a augmenté de façon significative au cours des dernières décennies. La sécurité des systèmes et des personnes repose sur la qualité de connecteurs électriques. Toutefois, soumis à des vibrations (moteur de la voiture, de l'environnement) des microdéplacements sont induits à l’interface. La problématique du contact électrique est principalement liée à l'altération de la conduction de faible courant (5mA) dans les interfaces soumises à des contraintes mécaniques de glissement répétitifs engendrant un phénomène bien connu de fretting par l’usure. La sollicitation de fretting usure apparait comme un processus de dégradation très pénalisant. Outre la détérioration des surfaces, ce processus conduit à une augmentation de la résistance électrique des contacts et à une possible perte du signal électrique. Ceci est particulièrement le cas pour les connecteurs bas niveau très sensibles aux fluctuations de la résistance électrique. Pour remédier à cela, les acteurs de la connectique développent de nouveaux dépôts pour limiter l’utilisation de dépôts nobles tels que l’or. Les objectifs de cette thèse sont d’établir une "table d’utilisation" des revêtements en fonction de sollicitations précises et de mettre en place une méthodologie dans le choix des dépôts en vue d’optimiser la durée de vie des connecteurs. L’étude aborde différents aspects tels que les influences des conditions de chargements mécaniques, des épaisseurs de dépôts, du type de dépôt (noble, non noble, dopé), de l’amplitude de débattement (micro-déplacement et grand déplacement) et la formalisation de l’endurance électrique (loi puissance et approche énergétique) In automotive applications and in other areas (energy, aviation, etc.), the number of electronic devices has increased significantly in recent last decades. Systems and people securities are based on the quality of electrical connectors. However, submitted to vibrations (car engine, environment) micro-displacements are induced at the interface. The problem of electrical contact is mainly due to the impairment of low current conduction (5mA) in interfaces subjected to repetitive sliding displacement generating a well-known fretting wear phenomenon. Fretting wear solicitation appears as a process of very detrimental degradation. Besides surface deterioration, this process leads an increase of the electrical contact resistance and a possible loss of the electrical signal. This is particularly the case of the low level connectors which are very sensitive to electrical contact fluctuations. To remedy, connections actors develop new deposits to limit the use of noble ones such as gold. The objectives of this thesis are to establish a "table of use" coatings based on specific solicitations and define a methodology for the selection of deposits to optimize the lifetime connectors. The study covers different aspects such as the mechanical loading conditions influence, the thickness deposits influence, the type of deposit (noble, non-noble, doped), the displacement amplitude (microdisplacement and large displacement) and the electrical endurance formalization (energetic approach and power law)

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Juřička, Viktor. "Vývoj polymerních správkových hmot s využitím druhotných surovin." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372189.

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The diploma thesis deals with the development of polymeric repair mortars in two qualitative levels ECONOMY and PREMIUM, designed especially for heavy engineering plants and the energy industry. In order to effectively withstand difficult industrial conditions, the developed materials should meet the highest requirements such as increased chemical and heat resistance, excellent adhesion to the concrete substrate, minimal shrinkage and other physical and mechanical properties. The PREMIUM level is aimed to achieve maximum physical and mechanical properties. Within the economy version, the emphasis is placed not only on very good properties, but also the possibility capability of reducing price of the resulting material. The partial aim of this work is the efficient use of secondary raw materials, mainly based on industrial waste in the form of fillers to the developed polymeric repair mortars.

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Jain, Shiwani. "Isotropically conductive adhesive filled with silver metalised polymer spheres." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/20297.

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Isotropic conductive adhesives (ICAs) have a growing range of applications in electronics packaging and have recently emerged as an important material in photo-voltaic module interconnections, particularly for thin-film and other non-silicon technologies where soldering processes are often unsuitable due to the nature of the metallisation or the limited maximum temperature the assembly can be exposed to. ICAs typically comprise of a high volume fraction of solid metallic flakes, usually silver, in an adhesive matrix because of its highly conductive oxide however, this thesis will focus on adhesives containing a large volume fraction of silver coated/metalised mono-sized polymer spheres (Ag-MPS). Incorporating silver coated mono-sized polymer spheres is anticipated to deliver specific advantages such as a significant reduction in the required silver content, improvement of the overall mechanical properties and flexibility to tune the properties of the filler according to the application compared with conventional flake filled adhesives. In this research advancements in the understanding of Ag-MPS filled ICAs, both through theory and experiments, have been made. Analytical models to predict an individual Ag-MPS resistance and Ag-MPS filled ICA resistance have been developed. The experiments based on the flat punch nanoindentation technique have been conducted to determine individual Ag-MPS resistances. The theoretical and experimental studies establish Ag-MPS diameter, coating resistivity, coating thickness, contact radius, and contact geometry as the main contributors towards the resistance of an Ag-MPS filled ICAs. These studies showed that Ag-MPS resistance decreases with increasing coating thickness and contact radius but increases with increasing coating resistivity. The experiments have also been conducted to investigate the effect of Ag-MPS volume fraction, diameter, coating thickness, curing conditions and shrinkage (affecting contact radius) on ICA conductivity and comparisons are made with flake filled and commercial ICAs. The results showed that ICA conductivity increases with increasing volume fraction and coating thickness but decreases with diameter. More importantly the results showed that conductivities similar to those of flake filled ICAs, including those commercially available, can be obtained using 70% less silver. The results show that, Ag content can be reduced further to just 7% with use of larger 30μm Ag-MPS but with a lower resulting conductivity. Thus for applications where very high conductivity is not required larger Ag-MPS may offer even greater potential cost benefits, which is something flake filled ICAs cannot offer. This is a significant achievement which can allow tuning of ICA formulations according to the demands of the application, which is not possible with the use of silver flakes as there is only a limited range of silver flake volume fractions that will yield useful levels of conductivity.

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Cayssials, Franck. "Prise en compte des propriétés viscoélastiques de colles structurales pour l'optimisation de joints adhésifs vis-à-vis de leur résistance au choc." Paris, ENSAM, 1995. http://www.theses.fr/1995ENAM0043.

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Si dans l'industrie automobile, le compromis prestation/fiabilité/cout est satisfaisant avec la technique d'assemblage par collage, une telle technique ne peut se limiter au choix d'un adhésif particulier. Il est indispensable d'optimiser le couple substrat-adhésif (et donc l'adhésif), vis-à-vis de sa résistance au choc. Dans la présente étude, nous nous sommes attaches a démontrer le bon comportement au choc d'un assemblage colle tôle/adhésif/tôle en prenant en compte les propriétés viscoélastiques de l'adhésif et en étudiant l'influence de certaines charges. Nous avons notamment pu mettre en évidence les mécanismes moléculaires responsables du comportement macroscopique d'un adhésif époxyde modifie. La confrontation des résultats expérimentaux a deux modèles théoriques, le modèle d'Eyring-Bauwens et le modèle d'Escaig, montre que la très bonne tenue au choc de l'adhésif est directement liée à la présence de la transition secondaire dans les gammes de températures et de vitesses explorées. L’effet de la nature, du taux et de la forme des charges incorporées dans la matrice époxyde sur la tenue mécanique de l'assemblage est aussi pris en compte

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Liptak, Stephen C. "Modification, curing and flame retardation of epoxy resin networks." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-11082006-133628/.

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Graiff, Lorenzo. "Dispositivi protesici in Odontoiatria Digitale: dall'impronta digitale intraorale alla produzione con tecnologie Cad-Cam. Caratterizzazione in vitro della precisione di accoppiamento e delle proprietà meccaniche." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424453.

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The objective of this work is to study some various aspects of the modern digital workflow to produce Fixed Dental Prostheses (FDP): from the optical impression, directly in the mouth, to the finalization of the prosthetic device specific for the patient. The motivation of this study is related to the growing need around the dental world to optimize and modernize the workflows that are still essentially artisanal. Taking advantage of modern digital technologies, that are rapidly spreading in the dental field, it is possible to obtain products with the highest quality standards, with lower production costs. Moreover it is important to spread the knowledge and skills to the dentists and to the dental technicians for an optimal use of these knowledges. In particular, we have have taken into consideration the following issues of distinct particular clinical importance: - optical intraoral scanning technology: specific operative and technical performance of these digital devices were investigated with particular reference to edentulous patients who need a full-arch implants rehabilitation, - innovative ceramic materials, used to produce metalfree multilayer bridges on natural teeth using Cad-Cam technology. It was also investigated an innovative resin composite material, which is also workable with Cad-Cam technology and used for the production of single crowns on implants. The revision of the scientific literature, suggested goals and metrological aspects of the experimental program of this research. The investigations, have evaluated precision and accuracy aspects of the optical impression of implants position, the geometric coupling precision of the multilayer metal free bridge components, mechanical resistance of different types of materials, and adhesion between a recent Cad-Cam resin composite referred as, Resin Nano-Ceramic (RNC) and zirconia. Moreover the introduction of instruments and methods established in the technical-scientific field, has been provided suitable to characterize the manufacturing processes used, the materials used and the devices manufactured. More in detail, the activities involved: 1. the study, in terms of metrological performance, of the acquisition process performed by the True Definition Scanner using a clinical sample reproducing a fully edentulous arch rehabilitated with 6 implants, 2. the verification of the geometric precision of the coupling component, sub and superstructure, of multilayer metalfree bridges made with different ceramic materials (zirconia-lithium disilicate), produced by Cad-Cam technology, and assembled by two different operators; the assembly / union of the bridge components, is instead carried out manually by the dental technicians totally handmade; 3. the analysis of the mechanical behavior, static, of the multilayer metalfree bridges, cited in paragraph 2, compared with another type of multilayer prosthesis (from the same Cad projects) but made with zirconia and glass ceramic (RLT), 4. the analysis by mechanical test, both static and under fatigue, of an innovative composite material resin supplied in blocks for Cad-Cam processing: Lava Ultimate. This new composite material presents, mechanical properties (Young's modulus), more similar to the natural tooth, compared to other aesthetic materials. For this reason, it was used to produce single crowns on implants comparing two different modes of use: cementing a composite crown produced with Cad-Cam technology directly on a titanium standard abutment supplied by industry, or producing a Cad-Cam zirconia customized abutment and cementing the composite crown to this; 5.verification of bonding capacity between zirconia and Lava Ultimate, using two different resin cements by means of shear bond test. Based on the results of the test campaigns conducted in this study it can be stated that: 1 technologies of digital intraoral optical impression are able to fulfill the clinical requirements of precision even in the case of full arch implants rehabilitations, 2. multilayer metalfree bridges, made with Cad-Cam technology according to the precision requirements of digital workflow, are affected by the intervention of the dental technician during the final assembly of the bridge components, resulting in reduced quality of precision established in the Cad phase, 3 multilayer metalfreee bridges show fracture toughness values greater than or equal to the minimum values reported in the scientific literature, 4. the implants crowns made with the innovative composite material subjected to strength tests and fatigue resistance, when cemented on an customized zirconia abutment, have superior mechanical characteristics than the cheapest solution, which provides the composite crown cementation directly to a standardized titanium abutment, 5. the use of adhesive cements for luting Lava Ultimate on zirconia, allowed to highlight the opposite results regards the strenght of adhesion, measured by means of the shear bond test. L’obiettivo di questo lavoro è studiare alcuni aspetti della moderna filiera produttiva digitale di manufatti protesici in campo dentale: dalla realizzazione dell’impronta ottica, direttamente nel cavo orale, alla finalizzazione del dispositivo protesico individualizzato per il paziente. La motivazione di questo studio risiede nell’esigenza sempre più sentita da parte di tutto il mondo dentale di ottimizzare e modernizzare i flussi di lavoro che sono ancora essenzialmente artigianali. Sfruttando le moderne tecnologie digitali, che si stanno rapidamente diffondendo in campo dentale, è possibile ottenere prodotti finiti di più alto standard qualitativo a fronte di costi di realizzazione più contenuti a condizione di diffondere ai clinici ed agli odontotecnici le conoscenze e le competenze necessarie all’utilizzo ottimale. In particolare sono stati presi in considerazione i seguenti temi di particolare rilevanza clinica: - la tecnologia di scansione ottica intraorale: sono state indagate le specificità operative e le prestazioni tecniche in particolare riferimento all’impiego per edentulie totali riabilitate mediante impianti, - i materiali ceramici innovativi, lavorabili mediante tecnologia Cad-Cam ed impiegati per realizzare protesi a ponte su denti naturali di tipo multilayer metalfree. E’ stato inoltre indagato un innovativo materiale in resina composita, anch’esso utilizzabile con tecnologia Cad-Cam ed impiegato per la realizzazione di corone singole su impianti. La revisione della letteratura tecnico scientifica, ha suggerito gli obbiettivi e gli aspetti metrologici del programma di ricerca sperimentale da condurre. Le indagini hanno riguardato aspetti di precisione ed accuratezza della lettura ottica della posizione degli impianti, di precisione geometrica di accoppiamento di protesi multilayer metal free, di resistenza meccanica di diversi tipologie di materiali e di adesione tra un recente composito a matrice resinosa, denominato Resin Nano-Ceramic (RNC) e zirconia; hanno previsto l’introduzione di strumenti e metodi consolidati in campo tecnico-scientifico, adatti a caratterizzare i processi di fabbricazione utilizzati, i materiali impiegati e i dispositivi realizzati. Più in dettaglio, l’attività ha riguardato: 1. lo studio, in termini di prestazioni metrologiche, del processo di acquisizione effettuato mediante il sistema di scansione True Definition Scanner su un campione clinico riproducente un'arcata completamente edentula riabilitata con 6 impianti; 2. la verifica della precisione geometrica di accoppiamento delle componenti, sotto e sovrastruttura, di protesi metalfree multilayer realizzate con materiali ceramici diversi (zirconia-disilicato di litio) prodotte mediante tecnologia Cad-Cam, e assemblate da due operatori diversi; l’assemblaggio/unione delle componenti, dei singoli ponti, viene invece realizzato manualmente dall’odontotecnico con tecnica totalmente artigianale; 3. l’analisi del comportamento meccanico, statico, delle protesi metalfree multilayer, citate al punto 2, confrontate con un altro tipo di protesi multilayer (provenienti dagli stessi progetti Cad) ma costituite da zirconia e ceramica feldspatica (RLT), 4. l’analisi mediante prova meccanica, statica e a fatica, della resistenza di un innovativo materiale in resina composita fornito in blocchetti per lavorazione Cad-Cam: Lava Ultimate. Questo nuovo materiale composito presenta, rispetto ad altri materiali estetici quanto a proprietà meccaniche dichiarate, (modulo di Young), un comportamento più simili al dente naturale. In quest’ottica, è stato utilizzato per realizzare corone singole su impianti, confrontando due modalità diverse di impiego: cementando una corona realizzata con questo composito e prodotta con tecnologia Cad-Cam direttamente su un pilastro standard in titanio fornito dall’industria, o realizzando con lavorazione Cad-Cam una sottostruttura in zirconia individualizzata e cementando su quest’ultima la corona in composito; 5. la verifica delle capacità adesive tra zirconia e Lava Ultimate, utilizzando due diversi cementi resinosi mediante test di taglio. Sulla base dei risultati delle campagne sperimentali condotte in questo studio è possibile affermare che: 1 le tecnologie di impronta ottica digitale intraorale sono in grado di rispondere ai requisiti clinici di precisione anche nel caso di arcate complete riabilitate su impianti, 2. le protesi multilayer metalfree, realizzate con tecnologia Cad-Cam secondo i requisiti di precisione propri dal workflow digitale, risentono dell’intervento di assemblaggio finale che esegue l’odontotecnico, con conseguente riduzione delle qualità di precisione stabilite in fase progettuale, 3. i ponti multilayer metalfreee presentano valori di resistenza alla frattura superiori o uguali ai valori minimi riportatati dalla letteratura scientifica 4. le corone su impianti realizzate con l’innovativo materiale composito, sottoposto a prove di resistenza statica e a fatica, quando cementate su un moncone individualizzato in zirconia, hanno caratteristiche meccaniche superiori alla soluzione più economica, che prevede la cementazione della corona direttamente ad un pilastro standardizzato in titanio. 5. l’utilizzo di cementi adesivi per cementare Lava Ultimate su zirconia, ha permesso di evidenziare comportamenti opposti per quanto riguarda le forze di adesione misurate con il test di taglio.

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Belov, D. S., A. O. Volkhonsky, Blinkov I. V, E. A. Skryleva, and J. Michalski. "Multilayer Nanostructured Wear-Resistant Coatings with Increased Thermal Stability, Adapted to Varying Friction Conditions." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35318.

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The work covers studying of influence of indexes of an ion-plasma vacuum-arc deposition method to the structure, composition and properties of Ti-Al-N/Zr-Nb-N/Cr-N multilayer nanostructured coatings (MNC). The average crystallites size within the layers is about 5-10 nm. Received coatings are featured by absence of any change in the composition and properties after heating up to 1000 ºС, the coatings hardness is up to 36,6GPa, Young's modulus of elasticity is up to 580 GPa, plastic work of deformation is up to 64 %, adhesive strength is about 100 N and coefficient of friction is 0,45. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35318

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Tong, Tianjian. "Co-effects of calcium carbonate and sodium bisulfite modification on improving water resistance of soy protein adhesives." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14196.

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Master of Science Department of Grain Science & Industry Xiuzhi Susan Sun Bio-based protein adhesives derived from renewable resources, especially soy protein are becoming more significant due to the concerns about environment and health related issues and the limit of petroleum recourses. However, the relatively poor water resistance of soy-based protein adhesives limits its wide applications. The goal of this study was to improve the water resistance performance of soy-based protein adhesives by chemical modification. The specific objectives are 1) to modify soy protein with calcium carbonate (CaCO[subscript]3) and sodium bisulfite (NaHSO[subscript]3) as the denaturing agents; 2) to investigate the effects of calcium carbonate (CaCO[subscript]3) concentrations, curing time and curing temperatures on adhesion performance of the modified soy-based protein adhesives. In this study, the co-effects of NaHSO[subscript]3 and CaCO[subscript]3 on adhesion properties of soy protein adhesives were investigated. NaHSO[subscript]3 was added to soy flour slurry at constant concentration 6g/L, while concentration of CaCO[subscript]3 was chosen in the range of 0 to 23g/L. Soy protein adhesives modified with 4g/L and 16g/L CaCO[subscript]3 were selected to characterize the adhesion performance on 3 ply yellow pine plywood using the Response Surface Method (RSM). The effects of curing temperature and curing time on the adhesion properties were also studied. The major findings are 1) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 modified soy protein adhesives (MSPA) had better adhesion performance (both dry and wet) than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA; 2) Higher temperature (170°C) resulted in higher wet shear adhesion strengths; 3) Longer hot press time had positive impact on wet adhesion shear strength; and 4) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA showed better adhesion shear strength after 2 weeks storage than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA. In general, 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA, under longer hot press time and higher temperature would lead to a better adhesion performance.

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Worschech, Claudia Cia. "Resistencia a fratura de pre-molares com preparos cavitarios extensos restaurados atraves de sistemas adesivos e não adesivos." [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289725.

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Orientador : Luis Roberto Marcondes Martins Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba Made available in DSpace on 2018-07-28T01:38:07Z (GMT). No. of bitstreams: 1 Worschech_ClaudiaCia_M.pdf: 487323 bytes, checksum: 63eea6a7fe297dfbe424400140e629bb (MD5) Previous issue date: 2000 Resumo: O propósito deste estudo foi avaliar a resistência à fratura de pré-molares superiores com extensos preparos cavitários e restaurados com sistemas adesivos e não adesivos. Trinta pré-molares superiores extraídos e livres de cáries ou fendas foram aleatoriamente divididos em 6 grupos com 5 dentes cada. Os dentes do grupo 1 não receberam preparos cavitários mésio-oclusais (controle positivo). No grupo 2, os dentes receberam preparos cavitários, mas não receberam restaurações (controle negativo). Os grupos 3, 4, 5 e 6 receberam os preparos cavitários e foram restaurados de acordo com os respectivos grupos experimentais: G3: Single Bond + Solitaire; G4: Single Bond + Z250; G5: Amálgama (Dispersalloy); G6: Amálgama (Dispersalloy) + Panavia. Todos os grupos foram submetidos ao teste de resistência à fratura numa Máquina de Ensaio Universal (Instron). O carregamento foi aplicado verticalmente através de uma esfera metálica de 4,7 mm de diâmetro, posicionada sobre as vertentes das cúspides dos pré-molares, numa velocidade de 0,5 mm/ min. As médias de carregamento necessárias para fraturar as amostras em cada grupo foram (em kgf), G6 = 168,46 (A) ; G5 = 155,19 (A) ; G1 = 153,54 (A) ; G4 = 148,86 (A); G3 = 80,08 (B) ; G2 = 20,51 (C). Os resultados do teste de TUKEY revelaram diferenças entre os grupos mostrados acima com letras diferentes. Assim, pôde-se concluir que os pré-molares restaurados através dos materiais citados foram capazes de resistir à fratura tanto quanto um dente íntegro, exceto aqueles restaurados com resina composta Solitaire Abstract: The aim of this study was to evaluate the fracture resistance of maxillary premolars with large cavities preparations. Thirty extracted maxillary premolars, sound and free from cracks were randomly assigned to six groups of five teeth each. The teeth from group 1 did not receive cavity preparations (positive control). In group 2, the teeth received preparations but did not receive restorations (negative control). From groups 3 to 6, the teeth received MO preparations and were restored according to the following techniques: G3: single Bond + Solitaire; G4: Single Bond + Z250; G5: Amalgam; G6: Amalgam + Panavia. All groups were submitted to fracture resistance test in a Universal Test Machine (Instron). The load was applied vertically through a metallic sphere of 4,7 mm diameter, touching only the cusps and never the restorations or cavity margins. The average load necessary to fracture the samples in each group was (in Kgf), G6= 168,46 (A); G5 = 155,19 (A) ; G1=153,54 (A) ; G4= 148,86 (A); G3= 80,08 (B) ; G2= 20,51 (C). The data were submitted to Tukey¿s test that revealed differences among some groups showed above with different letters. These results show that all materials tested can recover the fracture resistance of maxillary premolars as much as a sound tooth, except Solitaire resin Mestrado Dentística Mestre em Clínica Odontológica

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Sauveur, Juliette. "Development and characterization of models of resistance to T-DM1." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1266/document.

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Le T-DM1 est un immunoconjugué composé de l'anticorps trastuzumab qui cible HER2 lié au DM1, un agent anti-tubuline dérivé de la maytansine. Malgré son efficacité, la résistance acquise au T-DM1 a été démontré lors des tests précliniques et chez certains patients. Nous avons développé des lignées résistantes à partir de la lignée de cancer du sein MDA-MB-361 et de la lignée de cancer de l'œsophage OE-19, que nous avons exposées au T-DM1 à doses croissantes pendant une longue durée en absence ou en présence de ciclosporine A (CsA). A partir de ces conditions nous avons obtenus les lignées “TR” qui ont été exposées uniquement au T-DM1 et “TCR” qui ont été exposées au T-DM1 et CsA. Nous avons observé une augmentation de la vitesse de migration et une diminution de la force d'adhésion chez OE-19 TCR associées à une sensibilité accrue à un inhibiteur de RHOA. Aussi, la voie des prostaglandines était dérégulée chez OE-19 TR et TCR, avec une forte augmentation de l'expression de COX-2 et de prostaglandine E2 dans la lignée OE-19 TR. La sensibilité à l'aspirine, un inhibiteur des cyclooxygenases 1-2, était accrue chez les deux lignées OE-19 résistantes par rapport à la lignée parentale. En conclusion nous avons démontré que différentes voies de signalisation peuvent être impliquées dans la résistance au T-DM1. Nos résultats restent à être validés chez les patients. Nous suggérons que cibler la voie de régulation de la composition du cytosquelette ou la voie des prostaglandines pourrait permettre d'obtenir un effet thérapeutique dans le cas de cancers résistants au T-DM1 T-DM1 is an antibody-drug conjugate composed of the monoclonal antibody trastuzumab linked to DM1, a potent tubulin binding agent. Despite its efficacy in the treatment of HER2-positive breast cancer patients, acquired resistance to T-DM1 was observed during clinical trials. In order to study resistance mechanisms to T-DM1, we developed resistance models using OE-19 (esophageal) and MDA-MB-361 (breast) cancer cell lines in the absence or presence of ciclosporin A (CsA), an inhibitor of MDR1 mediated efflux. Resistant cells selected with T-DM1 alone are named “TR” and cells selected in the presence of T-DM1 and CsA are called “TCR”. OE-19 TCR cells showed modifications in adhesion gene expression, migration and adhesion strength, combined with an increased sensitivity to a RHOA inhibitor. Also, OE-19 TR cells presented an overexpression of COX-2 associated with an increased amount of PGE2 in the supernatant. A deregulation of the genes involved in the prostaglandin pathways was found in OE-19 TR and TCR cells, associated with increased sensitivity to aspirin. In conclusion, we found two signaling pathways deregulated in cell lines resistant to T-DM1. These results need to be validated using samples from patients resistant to T-DM1. Targeting the adhesion or the prostaglandin pathway could be of benefit for patients with T-DM1 resistant cancers

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Jeong, Seung Hee. "Soft Intelligence : Liquids Matter in Compliant Microsystems." Doctoral thesis, Uppsala universitet, Mikrosystemteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-281281.

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Soft matter, here, liquids and polymers, have adaptability to a surrounding geometry. They intrinsically have advantageous characteristics from a mechanical perspective, such as flowing and wetting on surrounding surfaces, giving compliant, conformal and deformable behavior. From the behavior of soft matter for heterogeneous surfaces, compliant structures can be engineered as embedded liquid microstructures or patterned liquid microsystems for emerging compliant microsystems. Recently, skin electronics and soft robotics have been initiated as potential applications that can provide soft interfaces and interactions for a human-machine interface. To meet the design parameters, developing soft material engineering aimed at tuning material properties and smart processing techniques proper to them are to be highly encouraged. As promising candidates, Ga-based liquid alloys and silicone-based elastomers have been widely applied to proof-of-concept compliant structures. In this thesis, the liquid alloy was employed as a soft and stretchable electrical and thermal conductor (resistor), interconnect and filler in an elastomer structure. Printing-based liquid alloy patterning techniques have been developed with a batch-type, parallel processing scheme. As a simple solution, tape transfer masking was combined with a liquid alloy spraying technique, which provides robust processability. Silicone elastomers could be tunable for multi-functional building blocks by liquid or liquid-like soft solid inclusions. The liquid alloy and a polymer additive were introduced to the silicone elastomer by a simple mixing process. Heterogeneous material microstructures in elastomer networks successfully changed mechanical, thermal and surface properties. To realize a compliant microsystem, these ideas have in practice been useful in designing and fabricating soft and stretchable systems. Many different designs of the microsystems have been fabricated with the developed techniques and materials, and successfully evaluated under dynamic conditions. The compliant microsystems work as basic components to build up a whole system with soft materials and a processing technology for our emerging society.

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David, Guy. "Traitements de surface et agents de couplage dentinaire : etude de la resistance mecanique du joint adhesif-dentine in vitro et in vivo." Paris 7, 1990. http://www.theses.fr/1990PA07GS01.

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Augustin, Till [Verfasser], and Bodo [Akademischer Betreuer] Fiedler. "Structural health monitoring of carbon fiber reinforced polymers and carbon nanotube modified adhesive joints via electrical resistance measurement / Till Augustin ; Betreuer: Bodo Fiedler." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2018. http://d-nb.info/1166754693/34.

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Al-Mansouri, Omar. "Behavior of bonded anchors in concrete under fire." Thesis, Ecole nationale supérieure Mines-Télécom Lille Douai, 2020. http://www.theses.fr/2020MTLD0011.

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La technique des ancrages par scellement chimique consiste à sceller une tige filetée dans un trou foré dans le béton durci grâce à une résine polymère. Les principaux avantages de cette technique sont la facilité d’installation et les propriétés mécaniques élevées de la résine à température ambiante. Grâce à l’adhérence de la résine, ce type d’ancrage peut être dimensionné pour avoir des performances similaires voire supérieures de celles des autres systèmes d’ancrages (mécaniques et coulés en place). En revanche, à hautes températures, e.g. incendie, l’adhérence de la résine se dégrade rapidement menaçant la capacité de l’ancrage à supporter les charges appliquées. Cela crée un risque sur les vies et les biens dans le bâtiment. Plusieurs accidents se sont produits comme l’effondrement du Big Dig Tunnel aux USA (2006) et le tunnel Sasago au Japon (2012) qui ont montré l’importance d’avoir des méthodes d’évaluation fiables de ce type d’ancrages. L’objectif de cette thèse est d’établir une méthode d’évaluation et une méthode de dimensionnement afin d’assurer la tenue structurale des ancrages par scellement chimique en situation d’incendie. L’étude est structurée en quatre parties :i. Protocoles expérimentaux pour les essais au feu des chevilles chimiques. Des essais d’arrachements au feu ont été réalisés sur des chevilles chimiques (résine époxy). Les profils de températures le long de l’ancrage ont été déterminés expérimentalement pour différentes configurations d’essais. Ensuite, ces profils thermiques ont été exploités comme données d’entrée pour calculer la résistance des chevilles par la méthode Pinoteau (intégration des résistances). Cette étude a permis de préciser les conditions expérimentales à utiliser pour l’évaluation des chevilles chimiques au feu.ii. Proposition d’un modèle de dimensionnement basé sur des calculs thermiques en utilisant la méthode des éléments finis en 3D. Les profils de température correspondant aux différentes configurations d’un ancrage dans le bâtiment ont été calculés à l’aide des propriétés thermophysiques des matériaux Eurocode pour le béton et l’acier. La modélisation en 3D a été comparée à la modélisation en 2D plane utilisée communément dans la littérature. Les deux approches ont été comparées aux mesures expérimentales et couplées avec la méthode Pinoteau pour évaluer l’influence de la méthode de modélisation sur le résultat de l’intégration des résistances. Suite à la validation du modèle 3D, des investigations thermiques ont été conduites sur d’autres paramètres pouvant influencer les essais au feu des chevilles chimiques. Cette étude a permis de valider la méthode de calcul en 3D comme la méthode la plus représentative du problème d’une cheville chimique au feu.iii. Validation de la méthode Pinoteau pour le dimensionnement des chevilles chimiques au feu en utilisant le modèle de dimensionnement proposé précédemment. Les calculs de la résistance au feu de trois chevilles chimiques différentes ont été comparés à des essais d’arrachement. Cette étude menée sur une large gamme de tailles de chevilles a permis de valider l’utilisation de l’intégration des résistances pour le dimensionnement.iv. Etude du comportement des chevilles chimiques dans le béton fissuré à hautes températures. Une méthode d’évaluation a été développée afin de déterminer la réduction de la résistance d’adhérence liée à la fissuration du béton, à hautes températures (chauffage électrique). Des essais ont été faits sur des chevilles chimiques (résine époxy) dans le béton fissuré et non-fissuré à température ambiante et à hautes températures. La réduction de la résistance avec l’augmentation de la température a été investiguée. Cette étude a permis d’obtenir une bonne répétabilité des résultats grâce à l’augmentation du nombre d’essais et le bon contrôle du scénario thermique appliqué The technique of bonded anchors consists of fastening a threaded rod in a drilled hole in hardened concrete by polymer adhesives. The main advantages of this technique are ease of installation and the high mechanical properties of the adhesive at ambient temperature. Due to the adherence of the adhesive resin, this type of anchors can be designed to ensure similar or even higher performances compared to other anchor systems (mechanical and cast-in). However, at high temperatures, e.g. fire situation, the adherence of the adhesive degrades rapidly. Fire decreases the adherence of the adhesive and leads to the inability of the anchor to support the fixed objects. This creates a risk on the lives and goods inside the building. Several accidents occurred like the collapse of the Big Dig Tunnel in the USA (2006) and the Sasago tunnel in Japan (2012) and highlighted the importance of having reliable evalutation methods of this type of anchors. The objective of this thesis is to establish an assessment and a design method to ensure the structural resistance of bonded anchors in fire situations. This project is structured into four main parts:i. Experimental protocols for fire tests on bonded anchors. Pull-out fire tests were conducted on bonded anchors (epoxy adhesive). Temperature profiles along the embedment depth of anchors were determined experimentally for different test configurations. Then, these temperature profiles were used as entry data to calculate the fire resistance of anchors using Pinoteau’s method (Resistance Integration Method). This study allowed to precise the experimental conditions to be adopted for fire evaluation of bonded anchors. ii. Proposition of a design model based on transient thermal calculations using finite element method in 3D. Temperature profiles were calculated using the thermophysical material properties of concrete and steel in the Eurocode. 3D modelling was compared to 2D modelling commonly used in the literature. Both approaches were compared to measurements during fire tests and coupled with Pinoteau’s method to assess their impact on the calculation of fire resistance of anchors. Following the validation of the 3D model, thermal investigations were conducted on other parameters that could influence fire tests of bonded anchors. This study allowed to validate the 3D modelling approach as the most representative of the problem of bonded anchors exposed to fire.iii. Validation of Pinoteau’s method for the design of bonded anchors under fire by using the previously proposed design model. Calculations of fire resistance of three different bonded anchor products were compared to pull-out tests. This study conducted on a wide range of anchor sizes lead to the validation of the Pinoteau’s Method for the design of bonded anchors.iv. Study of the behavior of bonded anchors in cracked concrete at high temperatures. An assessment method was developed to determine the reduction of bond strength due to cracked concrete, at high temperatures (electrical heating). Tests were conducted on bonded anchors (epoxy adhesive) in cracked and uncracked concrete, at ambient and high temperatures. The evolution of the reduction with temperature increase was investigated. This study ensured a good repeatability of test results due to the increased testing potential and the good control of the applied heating scenario

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Hodul, Jakub. "Vývoj speciálních sanačních hmot na beton pro extrémní namáhání s využitím druhotných surovin." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-401596.

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The doctoral thesis deals with finding the use of some waste and secondary raw materials in the production of special polymer remediation materials for concrete, which could be applied even in constructions, where extreme mechanical and chemical load is occurred. The aim of this doctoral thesis is experimental examination of the possibility of using selected types of waste, including hazardous waste which represent the highest risk to environment, and secondary raw materials as a substitute for the currently used primary fillers in order to reduce the ecological footprint of the product itself. Some types of secondary raw materials, such as filter fly ash contaminated by flue gas denitrification process, are no longer used as a concrete admixture or partial cement substitution due to unwanted release of toxic ammonia (NH3). Mainly for this reason, the thesis deals with the progressive utilization of such types of secondary raw materials as well as with another currently unused waste into polymeric patching, grouting and anchoring materials while preserving or improving the final properties compared to reference materials using only primary raw materials. The result of this thesis is to find out suitable formulations for efficient preparation of special polymeric remediation materials for concrete containing waste and secondary raw materials as fillers. The partial aim of the thesis and a the scientific contribution is an observation of the developed materials internal structure using a modern device, CT tomography, an influence of the filler type on the long-term durability, and last but not least the observation of the rate of pollutants incorporation, found in hazardous waste, into the polymeric matric with the aid of EDX and FTIR analysis.

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Dissertations / Theses on the topic 'Adhesion resistance'

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