Dissertations / Theses on the topic 'Cellular fibers'
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Roth, David Eugene. "Genetic Engineering of Functional Large Amyloid Fibers." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/78399.
Full textMaster of Science
Ledbetter, Nicole Verbeck Guido F. "Applications of nanomanipulation coupled to nanospray mass spectrometry in trace fiber analysis and cellular lipid analysis." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9760.
Full textNelson, Mark Tyler. "Biomimetic Electrospun Fibers for Cancer Cell Migration, Chemotaxis, andAnti-Metastatic Drug Testing." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429031970.
Full textLedbetter, Nicole. "Applications of Nanomanipulation Coupled to Nanospray Mass Spectrometry in Trace Fiber Analysis and Cellular Lipid Analysis." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9760/.
Full textBadauy, Cristiano Macabú. "Avaliação estrutural e diagnóstica de três lesões fibrosas da cavidade bucal." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/15449.
Full textThe objective of this study was to analyze the cellular and fibrous components of connective tissue in inflammatory hyperplasia (IH), oral fibroma (OF) and hereditary gingival fibromatosis (HGF), and to investigate the immunocompetence and to perform molecular analysis in HGF patients. To achieve the goals were developed 4 articles, with different methodologies and sample universes. In the 1st article, we intended to establish microscopic criteria to differentiate F and IH. The microscopic characteristics of the lesions (n=136) stained by hematoxylin-eosin (HE) and Masson trichrome were evaluated in an optical microscope. The results showed that a central area of wound collagen fibers and arranged in a higher density, surrounded by a layer of parallel fibers are characteristic of F, while the presence of epithelial hyperplasia, inflammatory infiltrate and parallel collagen fibers are characteristics of HI. These results led the 2nd article, which studied 18 F and 13 and IH, histologically prepared and stained by picrosírius red and direct blue for the direct quantitative assessment of collagen fibers and elastic fibers of the system, respectively, in the confocal laser microscope. The results confirmed the structural arrangement of collagen fibers found in Article 1, and indicate differences in the areas of collagen fibers in all regions studied. In order to evaluate the cellular and fibrous components of the 3 fibrous lesions, was developed the 3rd article. Specimens of the 3 lesions were studied in optical microscopy, to assess their populations of fibroblasts and inflammatory cells and the following components of fibrous connective tissue: collagen fibers, elastic fiber system, reticular fibers and oxytalan fibers. The results showed different arrangement and concentration of collagen fibers in the 3 lesions and a higher concentration of reticular fibers in HGF. The analysis of cellular components showed a greater number of fibroblasts in F and a higher count of inflammatory cells in IH. With the identification of a family with HGF, we chose to include it in the study because the lesions belong to the group of benign fibrous lesions. With that, it developed a 4th study, which used a similar morphologic evaluation of the 2 articles described above. Periferic blood was extracted from the HGF patients in order to determine the proliferative capacity of the peripheral lymphocytes, by the MTT test, and in order to sequence the SOS1 gene. The 3 HGF affected patients did not present the described mutation for the SOS1 gene, and the lymphocyte proliferative capacity in HGF patients was similar to those on controls. The results showed epithelial hyperplasia in the outer portion of the gingiva of patients with HGF, greater concentration of collagen fibers and few inflammatory cells. We can conclude that the 3 lesions present a different connective structure, considering both the quantitative aspect and the architectural disposition of their components.
Griebel, Matthew Alexander. "Viscoelastic Anisotropic Finite Element Mixture Model of Articular Cartilage using Viscoelastic Collagen Fibers and Validation with Stress Relaxation Data." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/743.
Full textKundrat, Mary Elizabeth. "A Comprehensive Series for Predicting Bone Dynamics: Forecasting Osseous Tissue Formation using the Molecular Structure of a Biomaterial." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1282842002.
Full textКомісаренко, Руслан Володимирович. "Реконструкція технологічного потоку Приватного акціонерного товариства "Київський картонно-паперовий комбінат" з виробництва паперу-основи для рушників." Master's thesis, Київ, 2018. https://ela.kpi.ua/handle/123456789/27136.
Full textRelevance of the theme: raising the level of quality of the paper-base for towels and productivity of technological equipment for the production of paper-base for towels at PJSC "Kyiv Cardboard and Paper Mill". Purpose and objectives of the study: development of measures and solving a number of problems with a view to reconstructing the technological flow of production of paper-based for towels and improving the quality of manufactured products. Object of research: technological process of paper production basis Object of research: the technological process of producing paper bases for towels. Subject of research: output fibrous semi-finished products, operating modes of equipment and technology for producing paper bases for towels. Methods of research: literary search, research of technological regimes, physical and mechanical methods of testing the samples obtained in laboratory conditions of the factory in the process of reconstruction of the technological flow. The practical value of the results: the reconstruction of the technological flow makes it possible to reduce the cost and, at the same time, improve the quality of finished products, produced at PrAT Kyiv Cardboard and Paper Mill Testing the results of the dissertation: the ways of reconstruction of the technological flow of the Private Joint-Stock Company "Kiev Cardboard and Paper Mill" for the production of paper for the basis for towels are proposed. The main stages of the reconstruction, presented in the dissertation, were reflected in the theses of conferences and articles: - Komisarenko RV, Ploskonos VG "Increasing profitability and saving energy in the production of sanitary-hygienic types of paper" \\ Zb.tez reports XXIII All-Ukrainian Sciences. Prakt.konf. studio, aspiration and young scientists "Equipment of chemical manufactures and enterprises of building materials", K .: 2018, 28-29.11, p.68-69. - Ploskonos VG, Komisarenko RV, Kotlyarskaya N.O., Yakimenko O.S. Use of fresh water in the processes of production of pulp and paper products and the need to reduce its consumption // International scientific and mathematical journal "Interna-nauka". - 2018. - № 17 (57), t.1, p.61-64. Publications: on the topic of the dissertation an article was published in the scientific-science journal "Internet Science" and 2 theses of reports at international and republican conferences.
Prasad, Saurabh. "Radio over fiber for 3G cellular System." Thesis, Kolhapur Institute of Technology College of Engineering, 2010. http://hdl.handle.net/10919/71529.
Full textWireless Optical Communication
Crapeau, Myriam. "Facteurs cellulaires déterminant la propagation du prion [URE3] dans la levure Saccharomyces cerevisiae." Thesis, Bordeaux 2, 2010. http://www.theses.fr/2010BOR21728/document.
Full textA prion protein can adopt two distinct conformations, one cellular and one prion. Prion conformation is the result of its aggregation into amyloid fibers. This fiber is the support of the prion information from which the cellular isoforms are converted into prion form by autocatalytic manner. The prion information transmission is therefore based on the transmission of this fiber during cell division, which is done by small polymers. These are the result of a balance between fragmentation and polymerization of the fiber. A disturbance of this balance causes a massive aggregation of the prion protein, leading to the prion information loss.The objective of my thesis was to understand what defined in vivo the prion transmission. My studying model was the Ure2p protein propagating the [URE3] prion in S. cerevisiae yeast. I showed that the Ure2p cellular concentration determined the aggregation speed of the prion protein and thus its transmission efficiency. Indeed, too high cellular concentrations are incompatible with the prion propagation. The cellular concentration of Ure2p also defines the prion strains diversity. A genetic screen allowed me to highlight that the presence of centrometric supernumerary sequences in the cell interferes with the [URE3] prion transmission. The same phenomenon is observed with an increase in the cell ploidy. In both cases, overexpression of the Hsp104 chaperone restores normal prion propagation
Zini, Laurent Yiou René. "La thérapie cellulaire de l'insuffisance sphinctérienne urétrale description d'un modèle animal préclinique et comparaison de 3 techniques de tranferts de cellules précurseurs musculaires /." Créteil : Université de Paris-Val-de-Marne, 2007. http://doxa.scd.univ-paris12.fr:8080/theses-npd/th0337593.pdf.
Full textJones, Willie F. "Development of a cellular fiber spinning technology for regenerative medicine." Connect to this title online, 2006. http://etd.lib.clemson.edu/documents/1173995215/.
Full textSetoodeh, Shahriar. "Optimal Design of Variable-Stiffness Fiber-Reinforced Composites Using Cellular Automata." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29204.
Full textPh. D.
Tonoli, Gustavo Henrique Denzin. "Fibras curtas de Eucalipto para novas tecnologias em fibrocimento." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-18022010-142936/.
Full textThis work evaluates the advantages of using hardwood short fibre pulp (Eucalyptus) as alternative to softwood long fibre pulp (Pinus) and synthetic fibres, traditionally used in reinforcement of cement based materials. The effects of cellulose fibre morphology (e.g., length, width, fibrillation, content of fines and number of fibres per gram) on the processing, on the mechanical and physical performance and on the microstructure of fibre-cement composites were evaluated. Composites were evaluated before and after accelerated ageing cycles. Eucalyptus pulp fibres were better dispersed in the cement matrix and provided higher number of fibres per unitary weight or volume, in relation to Pinus long fibre pulp. The short reinforcing elements lead to an effective crack bridging of the fragile matrix, which contributes to the improvement of the mechanical performance of the composite after ageing. These promising results show the potential of eucalyptus short fibres for reducing costs by both the partial replacement of expensive synthetic fibres in air curing process and the energy savings during pulp refining. The effects of pulp bleaching were also evaluated, and showed that Eucalyptus bleached fibres are more reactive to bond with the cement matrix by hydrogen bonds. Bleached fibres improved the fibre-matrix interface, although they presented more signals of fibre mineralization. Mechanical refining was used to change the morphological properties of Eucalyptus and Pinus pulps. Results show that high levels of refining were necessary for Pinus pulp to obtain cement retention values similar to those obtained by unrefined Eucalyptus pulp. The mechanical refining increased the capacity of the fibres to capture the mineral particles improving the adherence of the fibres with the matrix. This improved fibre-matrix interface led to better mechanical properties at 28 days of cure, but turned brittle the composites after 200 ageing cycles. The chemical surface modification of cellulose pulp fibres was done in order to improve fibre-matrix bonding and to decrease fibre mineralization into the composite. Surface modification of the cellulose pulps was performed with Methacryloxypropyltri-methoxysilane (MPTS) and Aminopropyltri-ethoxysilane (APTS) and showed significant influence on the microstructure of the composites. Accelerated ageing cycles decreased modulus of rupture (MOR) and toughness (TE) of the composites with unmodified and modified fibres, however composites reinforced with MPTS-modified fibres presented fibres free from cement hydration products, while APTS-modified fibres presented accelerated mineralization. Higher mineralization of the fibres led to higher embrittlement of the composite after accelerated ageing cycles. These observations are therefore very useful for understanding the contribution of the different fibre conditions (chemical composition, mechanical strength, morphology and surface properties) to the mechanisms of fibre-matrix adherence, fibre mineralization and degradation of fibre-cement composites.
Dean, Nancy Frier. "Plane front stability and cellular solidification in fiber reinforced aluminum-copper alloys." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13242.
Full textRao, Sanjeev. "Manufacture of cellular solids using natural fibre reinforced composites." Thesis, University of Auckland, 2009. http://hdl.handle.net/2292/5813.
Full textNkansah, Anthony Godfried. "Millimetre-wave over fibre systems for pico-cellular networks." Thesis, University of Kent, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497678.
Full textPunyamurthula, Deepthi. "Structural performance of low-profile FRP composite celluar modules." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3815.
Full textTitle from document title page. Document formatted into pages; contains xi, 91 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 83-85).
West, Douglas. "Design of a Fiber Optic Sensor Array for in Vitro Monitoring of Cellular Processes." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36635.
Full textMaster of Science
Flusberg, Benjamin Ari. "Cellular-level brain imaging in freely moving mice using fiber-optic fluorescence microendoscopy /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Full textDelfosse, Caroline. "Propriétés physico-chimiques et biologiques de fibres carbonées expérimentales." Lille 2, 2000. http://www.theses.fr/2000LIL2D001.
Full textDika, Nguea Hermine. "La culture de macrophages comme modèle prédictif de la toxicité et de la biopersistance des fibres minérales artificielles." Nancy 1, 2005. http://www.theses.fr/2005NAN11310.
Full textYao, Seydou. "Imagerie IRTF de haute résolution des interactions cellules-fibres pour l'étude des effets pathogènes des amiantes." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14611/document.
Full textLung disease as asbestosis and mesothelioma come from the interaction between asbestos fibers and human cells. The morphological and chemical heterogeneity of these fibers leads us to use analytical techniques capable of analyzing the organic/inorganic interaction. Our work aims the development of FTIR method couple with the synchrotron radiation. Thanks to that technique, we could analyse the effects of the asbestos fibers on a lung human cell. These technique has been developped on cultured cells directly on IR transparent substrates. The experimentation have been developped to in vitro RAMAN imaging of individual living cell in interaction with different types of fibers. The goal was a better understanding of the pathological effect of the asbestos fibers on the human lung cells
Charlet, Karine. "Contribution à l'étude de composites unidirectionnels renforcés par des fibres de lin : relation entre la microstructure de la fibre et ses propriétés mécaniques." Caen, 2008. http://www.theses.fr/2008CAEN2012.
Full textThis doctoral dissertation deals with morphological and mechanical characteristics of flax fibres. Indeed, due to their lightness and their good mechanical properties, these fibres are considered as good alternatives for the glass fibres commonly used as reinforcement in polymer composites. At first, sections and longitudinal profiles of flax fibres were observed in order to determine their mean sizes and their scattering and to draw up an internal organisation scheme. Then, tensile tests were then performed on elementary fibres. Their mechanical behaviour displays a typical elasto-visco-plasticity as well as an initial non-linearity which has been attributed to an internal rearrangement of the cell wall constituents. The comparison with other natural fibres and the observation of fibre rupture surfaces allowed to corroborate this hypothesis. The study of fibres issued from two varieties and from different parts of the stems led to the conclusion that the median fibres exhibited optimal dimensions as well as higher mechanical properties than the apical or the basal ones. Finally, unidirectional composites made of flax fibres and polyester were processed by hand lay-up or by compression moulding, with several fibre volume fractions. They were tensile and flexural tested in order to determine their mechanical properties and their damage modes. The results show that flax fibres reinforced composites, in addition to their ecological benefit, are mechanically competitive compared to glass fibres reinforced composites
Lafuste, Peggy Authier François-Jérôme. "Mécanismes moléculaires impliqués dans la fusion des cellules précurseurs myogéniques humains." Créteil : Université de Paris-Val-de-Marne, 2004. http://doxa.scd.univ-paris12.fr:80/theses/th0214091.pdf.
Full textLanore, Frédéric. "Maturation morpho-fonctionnelle de la synapse fibre moussue/cellule pyramidale de CA3 dans l’hippocampe." Thesis, Bordeaux 2, 2010. http://www.theses.fr/2010BOR21734/document.
Full textThe formation of synapses follows different steps including synaptogenesis and maturation. These different steps depend on coordinated pre- and post-synaptic assembly. Pre-synaptic proteins and ionotropic glutamate receptors play a central role in these processes. During my thesis, I have been interested in the implication of the presynaptic protein Bassoon in the maturation of the hippocampal mossy fiber to CA3 pyramidal cell glutamatergic synapses. This synapse constitutes an attractive model for the study of synaptic maturation because it follows several steps of defined morphological and functional maturation. Bassoon in one of the first protein present at newly formed synaptic contacts. By electrophysiological approaches, we showed that Bassoon is important for the organization of the active zone during the first two postnatal weeks.Kainate receptors play an important role in the regulation of network activity during postnatal development. However, the impact of kainate receptors activation on synaptic maturation is less known. I showed a delay in functional maturation of mossy fiber synapses in mice deficient for the GluK2 subunit of kainate receptors (GluK2-/-). To know if this delay is correlated to morphological alterations of this synapse, we setup in vivo lentiviral infections of membrane fluorescent protein (YFP) in mouse pups (P1-P2). Using confocal microscopy and 3D reconstruction, we described the morphological maturation of mossy fiber synapses. We were able to correlate functional and morphological maturation and our results also showed an impairment in the formation of mossy fiber synapses in GluK2-/-. Together, these data reveal the importance of synaptic activity and of the coordination of pre- and post-synaptic assembly during synaptic maturation
Vignaud, Timothée. "Production de forces par le cytosquelette d'actine : mécanismes et régulation par le micro-environnement." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY056/document.
Full textOur work has been focused on the regulation of the forces generated by the actin cytoskeleton. We have more precisely studied the role of the cellular microenvironment in this process. It was necessary to overcome some technical challenges to study these mechanisms. We developed two new techniques. The first one allows for the dynamic control of cell shape. A pulsed UV laser is used to modify the adhesive microenvironment around the cell and to create new area available for cell spreading. The second technique is an improvement of an existing technique from the laboratory. It consists in producing ECM protein islands on a elastic acrylamide substrate. This substrate provides the control of cell shape and internal organization. Plus, the elasticity of the substrate is compatible with traction forces measurements. The last technique combines acrylamide micropatterning and laser ablation of intracellular actin structures. Thus, the forces produced by a particular intracellular structure can be estimated. Two keys mechanisms of force regulation were shown. The use of mass spectrometry, traction force microscopy and molecular biology made it possible to study the interaction between different integrins in the adhesion complex. Cooperation was shown. It allows for the coupling between the architecture of the cytoskeleton and the amount of molecular motors in action. This process is necessary for the adaptation of cell forces to substrate stiffness. Actin structures are the one responsible for force production. This force can then be transmitted to the environment through adhesions.. The link between the length of actin fibers and the force produced was more precisely studied. The results showed a correlation between stress fibers length and the force generated inside it. This was true only above a certain critical value. After that, the force was rather decreasing with increasing fiber length. This critical length corresponds to the maximal length of cell axis on infinite 2D substrate. Our main hypothesis is that a too high myosin/actin ratio will block the proper force production/transmission within the fiber. Disassembly of actin by myosin or limited pool of actin are the two explanations we are currently following. The combination of these two-regulation process put brakes on force production by the cell. Above a certain length, the force produced is decreasing. This decreases in turn the strength of the adhesions anchored to these fibers. This will destabilize the adhesions and causes cell retraction The interplay between the regulation by the adhesion and the production of forces within the fiber set some limits on the level of forces produced by the cell. These processes are likely to be modified in a pathological context and can lead to tumor formation. They also protect the cell from being destroyed by stretching. If the length/stretch is too high, the cell will decrease its forces and detach from neighboring cells. This provide a system protecting the cell from being destroyed by massive deformations within the body
Théry, Manuel. "Contrôle de la polarité des cellules adhérentes : utilisation de micro-patrons adhésifs pour la manipulation de l'architecture cellulaire et l'analyse quantitative de l'organisation des cellules en interphase et en mitose." Phd thesis, Université Paris-Diderot - Paris VII, 2006. http://tel.archives-ouvertes.fr/tel-00012058.
Full textNous avons utilisé la technique d'impression par micro-contact pour manipuler la forme des cellules et la distribution de leurs adhésions. Les cellules adoptent l'enveloppe convexe du patron adhésif quelle que soit sa géométrie. Si, par exemple, les cellules sont contraintes de s'attacher à un T ou un V, sans pouvoir établir de contact en dehors de ce patron, elles adopteront dans les deux cas la même forme triangulaire. Nous avons utilisé cette propriété pour imposer aux cellules des formes identiques sur des patrons adhésifs différents afin d'analyser le rôle spécifique de la distribution des adhésions sur l'organisation du cytosquelette et des compartiments intracellulaires.
Nos mesures montrent que les cellules développent des tensions élevées dans les filaments d'actine, assemblés en fibres de stress, au-dessus des zones non adhésives. Sur les zones adhésives, la tension est plus faible, et la polymérisation de l'actine en un réseau branché induit la formation de protrusions membranaires. La localisation des protrusions est donc complémentaire de celle des zones contractiles.
Cette polarisation du système actine dirige le recrutement de certaines protéines dont l'activité influence la dynamique des microtubules. La croissance des microtubules en contact avec le cortex cellulaire est modulée différemment selon que l'actine forme des fibres de stress ou un réseau branché. Cependant, quel que soit le comportement des extrémités du réseau de microtubules à la périphérie, le centre du réseau, le centrosome, se maintient toujours au centre de la cellule. Le noyau est exclu de ce centre et se positionne vers les zones de contraction. Ainsi, à l'intérieur de la cellule, l'orientation de l'axe noyau-centrosome répond à l'asymétrie établie en périphérie.
La polarité du cortex est conservée pendant la division cellulaire ou mitose. Le corps cellulaire, qui s'est arrondi à l'entrée en mitose, est maintenu en contact avec le substrat adhésif par des fibres de rétraction riches en actine. Les mesures expérimentales de l'orientation des divisions, sur différents patrons adhésifs, révèlent que la distribution spatiale des ancrages de ces fibres sur la cellule guide l'orientation du fuseau mitotique, et par conséquent, le plan de division des cellules. En effet, les pôles du fuseau se positionnent en face des zones corticales où sont arrimées les fibres de rétraction, indépendamment de la forme qu'avait la cellule avant l'entrée en mitose.
Il existe des moteurs moléculaires ancrés dans le cortex des cellules et capables de tirer sur les microtubules astraux émanant des pôles du fuseau. En faisant l'hypothèse que ces moteurs ne sont activés que dans les zones où se situent les fibres de rétraction, on peut établir un modèle physique permettant de rendre compte de toutes les observations expérimentales effectuées.
Chaves, Vieira Lins Luanda. "Study and development of electrospun fibers for biotechnology application." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI073.
Full textCurrently, the electrospinning process is also one of the most promising routes for the design and development of polymer fibers. This technique is easy to use, unique, versatile, and low cost, which can be used to create fibers from a variety of starting materials. The structure, chemical and mechanical stability, functionality, and other properties of the fibers can be modified to match end applications. The first goal of this thesis was to develop scaffolds for the field of neural tissue engineering in order to mimic the biological, physical and mechanical properties of the native extracellular matrix. In the first time, the effect of fiber alignment of a biocompatible and fluorinated matrix denoted polyvinylidene fluoride (PVDF) was studied on the behavior of monkey neural stem cells particularly the morphology, cell adhesion and their differentiation in glial or neuronal cells. Secondly, bioabsorbable scaffolds composed of polylactide (PLA) and polyethylene glycol (PEG) polymers were synthesized to investigate the influence of the hydrophilic-hydrophobic balance on the culture of neural stem cells. Finally, an exploratory work was conducted to develop smart textiles based on poly(butylene adipate-co-terephthalate) (PBAT) containing curli as protein, well-known for its ability to chelate metals
Reye, John Timothy. "Enhanced enzymatic hydrolysis of cellulosic fibers by cationic polyelectrolytes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39633.
Full textDel, Broccolo Simone. "Effets de la topologie des cellules d'une structure en nid d'abeille." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCD001.
Full textHoneycomb sandwich panels are well known to provide interesting static out of plane properties because of their high equivalent stiffness whilst containing mass and for this reason, they are widely used as a ‘building brick’ in the Aerospace, Automotive and Naval industries. The environment in which these materials operate involve external forces which excites them in the mid-low frequency range. However, while a high stiffness/mass ratio is a desirable static property, the vibration frequency domain is usually in the high range and therefore they become poor mechanical and acoustic insulators within the frequency range they are usually subjected to. The question addressed then is simple: how periodic concepts can improve the broadband vibroacoustic signatures and performances of those structures? Most of vibroacoustic solutions are frequency band limited, specific and usually include the addition of mass, which for certain engineering segments is disadvantageous. Including vibroacoustic design rules at early stage of product development is one of the main research targets to improve their performance and would allow to design tuned structures without any later intervention or mass increment. This work focuses on investigating existing sandwich panel core topologies and attempt to create novel improved structures. The research was carried out trying to maintain the desired structural properties which justifies the usage of such solution in the first place but also considering its potential use as a platform for Multiphysics resonating periodic material inserts. Such cellular cores were manufactured using Kirigami, which is a variation of Origami, an ancient Japanese technique that consists in creating 3D structures by folding a 2D sheet of material. This manufacturing technique can be used as a systematic way to produce general honeycomb configurations with off-the-shelf long fibre composites by thermoforming and/or autoclaving. The main indicator on which I will focus to evaluate the vibroacoustic performance of the proposed innovative topologies will be the number and range of stopbands, also known as a bandgaps, which describe the frequency ranges in which elastic waves are not transmitted within the structure, in combination with the constituent material and its damping properties. This manuscript is organised in five chapters. The first one consists of a brief overview on periodic structures in the various engineering domains. Emphasis on Sandwich panels and their most popular manufacturing techniques will also be described. The second chapter will introduce the reader to the concept of elastic wave propagation in periodic media. Also, phenomena like Bragg or resonant bandgaps will be explained as well as the Floquet-Bloch theory applied to macro-scale structures such as aeronautical cellular cores.[...]
Rosales, Marc. "Study of SiGe HPT for radio over fiber applications." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1101/document.
Full textThis research is focused on the study of silicon germanium based heterojunction bipolar phototransistors (SiGe HPTs) implemented in an 80GHz SiGe Bipolar process technology. It's application in a radio over fiber system for home area networks are investigated. RoF for Home area networks are envisioned to implemented with a minimal system cost. Operation at 850nm is identified as a critical parameter to achieve this goal. Low cost off the shelf optical components are readily available at this wavelength. The use of multi mode fibers (MMF) as opposed to higher cost single mode fiber (SMF) is sufficient for the bandwidth requirements in a home network environment. A monolithically integrated OE receiver chip would help in the overall reduction of the system cost by having the optical detector in the same chip with the electronic circuits. We have designed and implemented three terminal HPT (3T-HPT) structures. The two main groups of the HPT structures are: 1) HPTs with extended Base and Collector regions (xBC HPT) and 2) HPTs with extended Emitter, Base and Collector regions (xEBC HPT). Variations to improve optical coupling the though optimizations in the vertical stack and lateral size of the HPT. The measurements and characterization showed that all the structures are compatible with the process technology. The type of biasing used in the base of the HPT also influences the HPT performance. A constant current (CC) bias has higher extracted DC responsivity as compared to a constant voltage (CV) bias. The effects of the different passive base loads on the HPT responsivity are studied through simulation and measurement of fabricated circuits. The impedance presented on the base has a great influence on the HPT responsivity. The performance of an HPT as circuit component is studied using different HPT-HBT pair configurations. Tests and measurements verify that improvement in the classical transistor pair configurations are also present in the opto microwave response of the HPT-HBT pair. Finally, SiGe hpt is used in the development of a ROSA module for a radio over fiber systems for home area network
Aymard, Christophe. "Rôle exercé par les fibroblastes dans la myogenèse de myotubes génétiquement atteints (souris muscular dysgenesis) et perturbation métabolique des fibroblastes du muscle mutant." Bordeaux 2, 1993. http://www.theses.fr/1993BOR28245.
Full textBjurhager, Ingela. "Mechanical behaviour of hardwoods : effects from cellular and cell wall structures." Licentiate thesis, KTH, Fibre and Polymer Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4830.
Full textSyftet med den här avhandlingen var att undersöka mekaniska egenskaper hos olika arter av lövträd, och koppla egenskaperna till cell- och cellväggsstrukturen i materialet. Arterna som omfattades av undersökningen var Europeisk asp (Populus tremula), hybridasp (Populus tremula x Populus tremuloides) och ek (Quercus robur). Arterna inom familjen Populus, inklusive den snabbväxande hybridaspen, har på senare tid kommit att användas inom ett stort antal projekt inom genforskningen. Det har i sin tur ökat behovet av noggrannare bestämning av mekaniska egenskaper hos dessa arter. Ek har sedan tusentals år tillbaka varit ett populärt konstruktionsmaterial; något som har resulterat i ett stort antal arkeologiska ekfynd. Konservering av dessa inkluderar ofta dimensionsstabilisering med hjälp av polyetylen-glykol (PEG); en kemikalie som man vet påverkar de mekaniska egenskaperna. I vilken utstäckning detta sker är däremot inte helt klarlagt. Studien på euoropeisk asp och hybridasp inkluderade utveckling av en ny metod för provning av små juvenila prov i grönt tillstånd. Töjningsmätningar gjordes med hjälp av digital speckelfotografering (DSP). Axiell dragstyvhet och draghållfasthet var av speciellt intresse. Sämre mekaniska egenskaper hos hybridaspen korrelerade med medelvärden på densitet, som var lägre för hybriden än för den Europeiska aspen.
Ek undersöktes i svällt tillstånd, där svällningen inducerades med hjälp av PEG (molekylvikt 600). Axiell dragstyvhet och draghållfasthet samt radiell tryckstyvhet och ytspänning undersöktes. Töjningsmätningar i axiell riktning gjordes med hjälp av videoextensiometer, medan töjning i radiell riktning gjordes med hjälp av DSP. Övrig karakterisering av materialet inkluderade scanning electron microscopy (SEM), röntgenmikrotomografi och wide angle X-ray scattering (WAXS) för bestämning av mikrofibrillvinkel. Axiell dragstyvhet och draghållfasthet påverkades bara marginellt av PEG-behandlingen. WAXS-mätningarna visade att mikrofibrillvinkeln i materialet var mycket liten. Därigenom blir de mekaniska egenskaperna i axiell riktning till stor del beroende av mikrofibrillerna, vilket samtidigt minimerar den mjukningseffekt som PEG-impregneringen har på cellväggsmatrisen. De mekaniska egenskaperna i radiell kompression påverkades däremot starkt negativt av impregneringen. Detta antogs bero på den försvagande och uppmjukande effekt som PEG:en har på de radiellt orienterade märgstrålarna i veden.
The aim of this work was to investigate the mechanical properties of different hardwood species and relate the properties to the structure at the cellular and cell wall level. The species examined were European aspen (Populus tremula), hybrid aspen (Populus tremula x Populus tremuloides) and European oak (Quercus robur). The Populus species, including the fast-growing hybrid aspen, are used in a large number of projects using transgene technology, which also has raised the demand for a more extensive determination of mechanical properties of the species. Oak have been a popular construction material for thousands of years, esulting in a vast number of archaeological findings. Preservation of these often includes dimensional stabilization by polyethylene glycol (PEG), an impregnation agent which affects the mechanical properties. To which extent is not properly investigated, however. The study on European and hybrid aspen included development of a method for tensile testing of small, juvenile specimens in the green condition, where strain was measured using the digital speckle photography (DSP) technique. Mechanical performance of the species in terms of longitudinal tensile stiffness and strength were of special interest. Inferior mechanical properties of hybrid aspen corresponded well to mean values of density, which were lower for the hybrid aspen compared to European aspen.
Oak was examined in the swollen state, where swelling was induced by PEG with molecular weight 600. Longitudinal tensile stiffness and strength as well as radial stiffness and yield strength in compression were compared. Longitudinal and radial strain was measured using video extensiometry and DSP, respectively. Additional characterization of the material included imaging from scanning electron microscopy (SEM), X-ray microtomography and determination of microfibril angle using wide angle X-ray scattering (WAXS). Tensile stiffness and strength in the axial direction were only slightly affected by PEG-impregnation. WAXS measurements showed that microfibril angles were close to zero which implicates that cell wall properties are strongly dependent on the microfibrils, and only marginally influenced by the plasticization effects from PEG on the lignin/hemicellulose matrix. In the radial direction, on the other hand, mechanical performance was strongly decreased by PEG-impregnation. This was believed to originate from softening of rays.
Lin, Wing Shan Linda. "Effect of moisture and other volatiles on the cellular structure of plastic/wood-fiber composite foams." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63121.pdf.
Full textWilkin, Linda D. "REHABILITATIVE INFLUENCE OF THERAPEUTIC ULTRASOUND TREATMENT ON CELLULAR MARKERS OF SKELETAL MUSCLE REGENERATION FOLLOWING BLUNT CONTUSION INJURY." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1029356546.
Full textJorapur, Nikhil Sudhindrarao. "Design, Fabrication and Testing of Fiber-Reinforced Cellular Structures with Tensegrity Behavior using 3D Printed Sand Molds." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/84531.
Full textMaster of Science
El-Turabi, Aadil. "Studies on fibre protein of human adenovirus type 3 and its cellular receptor." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400265.
Full textHocine, Malik Kugel Godefroy. "Croissance d'un micro-composant en bout de fibre optique par photopolymérisation." Metz : Université Metz, 2008. ftp://ftp.scd.univ-metz.fr/pub/Theses/2004/Hocine.Malik.SMZ0411.pdf.
Full textBourdon, Sylvie. "Développement d'une membrane à base d'un mélange de polymère, hydrophobe et de polymère hydrophile : élaboration, caractérisation et essais de filtration." Toulouse 3, 2002. http://www.theses.fr/2002TOU30248.
Full textVan, der Meeren Anne. "Facteurs de croissance produits par des cultures de cellules mésothéliales pleurales de rat transformées par des fibres d'amiante caractérisation et effets sur la prolifération et le cycle cellulaire /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37619045q.
Full textVan, der Meeren Anne. "Facteurs de croissance produits par des cultures de cellules mésothéliales pleurales de rat transformées par des fibres d'amiante : caractérisation et effets sur la prolifération et le cycle cellulaire." Paris 12, 1988. http://www.theses.fr/1988PA120025.
Full textGirault, Raynald. "Caractérisation biochimique des polymères incrustant les parois secondaires des fibres de lin." Rouen, 1999. http://www.theses.fr/1999ROUES055.
Full textLee, Hung-Tai. "Cellular and molecular studies of postembryonic muscle fibre recruitment in zebrafish (Danio rerio L.)." Thesis, St Andrews, 2010. http://hdl.handle.net/10023/901.
Full textMaingret, Vincent. "Modulation de la plasticité synaptique par les prostaglandines E2 à la synapse fibre moussue/cellule pyramidale CA3 en conditions physiologiques et dans un modèle murin de la maladie d'Alzheimer." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0313/document.
Full textAlzheimer’s disease (AD) is the most common form of dementia in elder people characterized by a loss of cognitive function linked to synaptic deficits. There is considerable evidence that neuroinflammation and AD are intimately linked. The key role of neuroinflammation in the course of the disease was figured out by epidemiological studies reporting a reduced prevalence to develop AD for patients chronically treated with Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). Prostaglandins are lipidic mediators derived from arachidonic acid and their synthesis is inhibited by NSAIDs. Among prostaglandins, PGE2 is known to modulate synaptic transmission and plasticity in the hippocampus and its concentration is higher in brains from AD patients. Numerous studies have reported synaptic deficits in the course of AD, mainly in the hippocampus which is essential for cognitive functions like learning or memory formation. The vast majority of these studies were focused on postsynaptic deficits at the canonical CA3-CA1 synapse. On the opposite, the synapse between mossy fiber and CA3 pyramidal cell (Mf-CA3) that express presynaptic short-term and long-term plasticity, was poorly studied in the context of AD. The aim of my project was to decipher the involvement of PGE2 in synaptic deficits in a mouse model of AD, the APPswe/PS1ΔE9 (APP/PS1). Our results show that acute application of PGE2 on wild type young mice impairs only presynaptic long term potentiation (LTP) at the Mf-CA3 synapse via the specific activation of EP3 receptor. In APP/PS1 mice, we demonstrate that the sole deficit at the Mf-CA3 synapse is an impairment of the presynaptic LTP at 12 months of age. Finally we demonstrate that the impaired presynaptic LTP in APP/PS1 mice can be rescued by the acute application of a specific EP3 receptor antagonist, pointing out the key role of PGE2 - EP3 signaling pathway in synaptic deficits in hippocampus in a mouse model of AD
Swieb, Salem Yiou René Saadia Eddahibi. "Développement de thérapies cellulaires pour les complications urinaires et sexuelles de la prostatectomie radicale." S. l. : Paris Est, 2008. http://doxa.scd.univ-paris12.fr:80/theses/th0417525.pdf.
Full textEname-Obiang, Paul Francis. "Utilisation des résonateurs hélicoïdaux comme cellules de mesures de la permittivité et comme applicateurs microondes pour le chauffage des matériaux." Nancy 1, 1995. http://www.theses.fr/1995NAN10010.
Full textBarbe, Laurent. "Mécanismes d'adhérence des leucocytes aux fibres synthétiques : application à la filtration du sang." Paris 7, 2001. https://tel.archives-ouvertes.fr/tel-00002228.
Full textChagnot, Caroline. "Colonisation de la viande par Escherichia coli O157∶H7 : caractérisation moléculaire, cellulaire et tissulaire des interactions." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22448/document.
Full textEscherichia coli O157:H7 is the most prevalent serotype involved in foodborne infection by enterohemorrhagic E. coli (EHEC). It is associated with life-threatening hemorrhagic colitis and the hemolyticuremic syndrome (HUS), which essentially affect young children. The major food vector of EHEC contamination is ground beef. The primary bacterial contamination occurs during the slaughter, essentially at dehiding stage where bacteria can be transferred from hides to carcasses. The connective tissue surrounding the muscle, highly similar to extracellular matrix (ECM) could potentially be a support for bacterial adhesion. When investigating the adhesion and colonization to the main muscle fibrous ECM proteins, the great influence of growth conditions on subsequent bacterial attachment was shown. Maximal adhesion to ECM proteins occurred at 25°C and pH 7, especially to collagens I and III. In EHEC, various surface-exposed protein determinants can be expressed and potentially involved in ECM adhesion. Investigating the autoaggregation, bacterial adhesion and biofilm formation, the involvement of Antigen 43 (Ag43), an autotransporter protein, was demonstrated in E. coli O157:H7 EDL933. Then, the attachment of E. coli O157:H7 to the meat was determined on two different model muscles, with different contractile and metabolic characteristic (Soleus oxidative, slow and EDL glycolytic, fast), previously characterized by UV microspectroscopy coupled to synchrotron radiation fluorescence. The different of muscle fiber types and the effect of a prolonged anoxia simulating maturing meat were discriminated by their spectral responses after excitation at 275 nm. It clearly appeared that bacteria displayed differential tropism as function of the muscle types, higher for the Soleus than the EDL muscles. While E. coli O157:H7 adhered similarly to the different types of muscle fibers, bacterial adherence essentially occurred at the ECM, pinpointing the key role of connective tissue for E. coli O157:H7 adhesion to meat. This first comprehensive investigation of bacterial adhesion to skeletal muscles at molecular, cellular and tissue levels provides new insight in the physiology of the colonization of meat by EHEC and constitutes a prerequisite for the development of innovative practices and strategies to minimize the risk of meat contamination
Badrinath, Krishan. "Founder Cell and Myoblast Interactions during IFM Myogenesis in Drosophila: the Regulation of Myoblast Proliferation, Fusion, and Fiber Formation." Miami University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=miami1229615387.
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