Дисертації з теми "3D cellular structures"
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Sangle, Sagar Dilip. "Design and Testing of Scalable 3D-Printed Cellular Structures Optimized for Energy Absorption." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1495467365594915.
Повний текст джерелаChu, Chen. "Design synthesis for morphing 3D meso-scale structure." Thesis, Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/34676.
Повний текст джерелаGoel, Archak. "Design of Functionally Graded BCC Type Lattice Structures Using B-spline Surfaces for Additive Manufacturing." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1552398559313737.
Повний текст джерелаJorapur, 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.
Повний текст джерелаMaster of Science
Carozzani, Tommy. "Développement d'un modèle 3D Automate Cellulaire-Éléments Finis (CAFE) parallèle pour la prédiction de structures de grains lors de la solidification d'alliages métalliques." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00803282.
Повний текст джерелаPineau, Adrian. "Modélisation 3D de structures de grains par une approche automate cellulaire. Application à la compétition de croissance dendritique et à la cristallisation du silicium polycristallin." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM042.
Повний текст джерелаGrains structures obtained during solidification processes strongly influence the properties of technical products. It is specially the case for cast parts in metallic alloys, or for silicon photovoltaic cells. The CA-FE (Cellular Automaton - Finite Elements) method aims to model grain structure evolution during solidification at a macroscopic scale, but also requires approximations at smaller scales. In this work, two distinct studies are proposed. First, CA simulations of growth competition among columnar dendritic grains are carried out for a succinonitrile-0.4 wt% acetone alloy. This is achieved by computing the grain goundary orientation during directional solidification. Comparisons are subsequently conducted with recent phase field results derived under the same conditions. An excellent agreement is found with phase field simulations results within arange of intermediate cell size centered around the maximum step between primary stationary dendrite tips of the two competing grains. The Esaka configuration, corresponding to a dendritic growth competition for a succinonitrile-1.3 wt% acetone alloy, is also studied. Polycristalline silicon growth was investigated within the ANR CrySaLID project. The CA method was enriched to allow facets growth and grains in twin relationship modeling. These developements use a geometrical approach based on in situ and ex situ experimental observations. The resulting numerical model was applied to experimental configurations and good qualitative and quantitative agreements were found. Simulations over a cubic and centimetric domain were lastly conducted. It was found that facets growth and twin nucleations strongly modify the grains structure compared to a dendritic microstructrure
Baux, Anthony. "Synthèse de matériaux alvéolaires base carbures par transformation d'architectures carbonées ou céramiques par RCVD/CVD : application aux récepteurs solaires volumiques." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0193/document.
Повний текст джерелаThe aim is to design and create efficient cellular architectures for volumetric solar receivers used in the future thermodynamic power plants. Three strategies are considered for the creation of ceramic or carbon preforms: (i) the synthesis of biomorphic materials resulting from the cutting of balsa, (ii) the elaboration of ceramic structures by binder jetting and (iii) the replication of polymer structures made by 3D printing, using a carbon or ceramic precursor resin. In all cases, the green preforms are converted by pyrolysis to C or SiC and an infiltration step / SiC coating by CVD (Chemical Vapor Deposition) completes the manufacture of ceramic structures. An intermediate stage of RCVD (Reactive CVD) was implemented during the first strategy, in order to convert the microporous carbonaceous structure into TiC. The composition, the microstructure and the porous architecture of the ceramic structures were first characterized. The characteristics of the most relevant materials, considering the application as a solar receiver, were then examined. The thermomechanical properties and the oxidation resistance have thus been characterized in priority. Permeability and thermo-radiative properties, which are also two important factors for application, were also considered
Bresteau, Enzo. "Adhesive Clathrin Structures Support 3D Haptotaxis Through Local Force Transmission." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS546.
Повний текст джерелаCell migration is a fundamental process in the development and homeostasis of multicellular organisms. It is also central to many pathologies and it is especially important for metastatic dissemination. When migrating, cells use adhesion structures to push on their substrate in order to move forward. We recently showed that clathrin coated structures, primarily known as endocytic structures, can also serve as adhesion structures. In this manuscript, I show that some ligands internalized through clathrin mediated endocytosis can also bind to the extracellular matrix and orient cell migration using adhesive clathrin structures.I first showed that ligand-decorated collagen fibers are associated with more clathrin structures and more protrusions. I then showed that cells applied more forces to the ligand-decorated collagen fibers and this extra amount of forces requires the presence of clathrin structures. Finally, I showed that cells can migrate following collagen-bound ligands in 3D, this directed migration also requiring the presence of clathrin structures. Such migration mechanism could be used by cells to follow in vivo gradient of matrix-bound ligands and thus find their way when migrating inside the body
Pietrzyk-Nivau, Audrey. "Génération de plaquettes in vitro à partir de cellules souches hématopoïétiques." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05P626/document.
Повний текст джерелаMegakaryopoiesis is a process allowing hematopoietic stem cell (HSC) to proliferate and differentiate into megakaryocytes (MK). It is followed by thrombopoiesis allowing blood platelet production. These processes occur 1) in the bone marrow three-dimensional (3D) structure, 2) in the bone marrow sinusoid vessels and 3) in the blood flow. Our general aim was to decipher the mechanism associated to each process. The first objective was to study the effects of porous 3D structure on MK differentiation and platelet production. This study demonstrated that the synergy between spatial organization and biological cues improved MK and platelet production. We also characterized platelets produced from mature MK in flow conditions, with respect to their in vitro and in vivo properties. We highlighted the capacity of flow-derived platelets to incorporate in a thrombus in vitro and in vivo, compared to static-derived platelets. These works represent some new developments for mimicking the bone marrow structure and to reproduce blood shear forces in order to improve and increase in vitro platelet production for therapeutic use
UREÑA, MARTÍN Carlos. "Study of Caveolae Mechanotransduction Under 3D Compressive Stresses : Comparative Analysis of 2 Models Mimicking Structural and Mechanical Tumor Characteristics." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS525.
Повний текст джерелаMechanics and compressive stress play an important role in tumor progression. Recently, several approaches have been developed to test compressive stress in 3D in vitro models. In the present work, we first show the relevance of compression in the organization of cancer associated fibroblasts (CAFs), enwrapping cancer cells upon 3D isotropic compression in capsules of hollow alginate. In this system, CAFs cover cancer cells in the presence of compression by a process which most likely involves fibronectin deposition reorganization, and not a passive rearrangement of the two spheroids. In the second part of this work, we investigated the response of caveolae components to compressive stress. Caveolae are plasma membrane invaginations which are able to buffer membrane tension, thus protecting the cell from bursting. Here, we show how caveolae reduce their presence under 3D short term compression, and how this compression inhibits interferon induced STAT1 and STAT3 activation. Moreover, long term effects of compressive stress in spheroids result also in loss of the caveolae component EHD2, acentral ATPase for caveolae stability on the membrane. Lastly, we found different pathways with altered gene transcription after compressive stress. Among them, we characterized the effect of caveolin-1 loss on the release of exosomes under 3Dcompression
Chen, Shijia. "Modélisation tridimensionnelle Automate Cellulaire - Éléments Finis (CAFE) pour la simulation du développement des structures de grains dans les procédés de soudage GTAW / GMAW." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2014. http://pastel.archives-ouvertes.fr/pastel-01038028.
Повний текст джерелаDas, Pritam. "Membrane micro-structurée utilisable comme support au développement de cellule humaine : développement, caractérisation et interaction cellule-matrice." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30282/document.
Повний текст джерелаOver the last decades, three-dimensional (3D) scaffolds are unfolding many promising applications in tissue engineering and regenerative medicine field by providing suitable microenvironment for the incorporation of cells or growth factors to regenerate damaged tissues or organs. The three-dimensional polymeric porous scaffolds with higher porosities having homogeneous interconnected pore network are highly useful for tissue engineering. In this context, a poly (ε- caprolactone) PCL/chitosan CHT blend membrane with a double porous morphology was developed by modified liquid induced phase inversion technique. The membrane shows: (i) surface macrovoids (big pores) which could be easily accessible for cells invasion and viability; (ii) interconnected microporous (small pores) network to transfer essential nutrients, oxygen, growth factors between the macrovoids and throughout the scaffolds. The physico-chemical properties (pore size, surface chemistry and biodegradability) of the materials have been characterized. This study shows how it is possible to tune the membrane properties by changing the PCL/CHT ratio. Human mesenchymal stem cell (hMSCs) culture was performed on the membranes and the cell viability and proliferation was investigated by MTT assay and oxygen uptake rate experiments. The experiments demonstrate that the membranes are biocompatible and can be colonized by the cells at micron scale. Confocal microscopy images show that the cells are able to adhere and penetrate inside the macrovoids of the membranes. Both cell proliferation and oxygen uptake increase with time especially on membranes with lower chitosan concentration. The presence of chitosan in the blend produces an increase of porosity that affect the entrapment of the cells inside the porous bulk of the membranes. Successful cellular proliferation of hMSCs could be useful to enhance longevity of other primary cells by production of corresponding growth factors. To test the dynamic behavior of cells on the membranes, an organ-on-chip (OOC) device has been developed with human umbilical endothelial cells (HUVECs) seeded on the membrane. The hydraulic resistance of the cellular barrier on the membrane has been quantified for real time trans-endothelial pressure (TEP) 20 cmH2O at 37 degree C and with living cells after 1 day and 3 day of post seeding. Results suggests this kind of polymeric scaffolds can be useful in future as an in vivo patch to repair disrupted vessels
Bouyer, Charlène. "Manipulations acoustiques de cellules pour l'ingénierie tissulaire." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10297/document.
Повний текст джерелаGenetic or physical cells manipulation aspires to be new challenges in tissue engineering. Current technologies to generate tissues, such as micro-scale hydrogels (microgel) assembly, scaffold seeding, molding or bio-printing suffer from the difficulty to control cells organization, multi-steps time consuming procedures and/or potentially cytotoxic side effects. In this PhD, we aimed at developing cell-friendly and rapid techniques, easily transferable to biological laboratories, for two broadly challenging applications: bone healing and neural tissue engineering, for which the above-mentioned techniques cannot yet provide widely reliable models. In case of a bone critical size defect, external help is often needed for bone healing, and gold-standard for care is bone autograft. Alternatively, the fracture healing process can be stimulated and restored by the implantation at the fracture site of hydrogels embedding growth factors. Both technologies suffer however from side effects such as donor site morbidity or cells over-proliferation in the hydrogel proximity. Moreover, the kinetic of growth factors release cannot be temporally controlled. In this work, we aim at developing an alternative method using ultrasound to spatially and temporally control growth factors release within a biocompatible material: fibrin hydrogels. Towards this goal, we encapsulated, in lipoplexes, plasmids that are under the control of a heat-shock promoter. We then transfected cells, stimulate the production of the targeted protein by heat shock and reported its expression. We also optimized an encapsulation protocol for cells within fibrin gels. This proof of concept demonstrates the feasibility of transfection by lipoplexes with a plasmid under control of heat shock, and pave the way for future developments of in situ transfection of autologous cells, for a tight temporal and spatial control of therapeutic proteins expression using ultrasound-induced hyperthermia
Najjar, Riham. "Etude structurale par RMN et modélisation moléculaire de peptides urotensinergiques, impliqués dans la régulation du système cardiovasculaire et la prolifération des cellules tumorales." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR038.
Повний текст джерелаThis work aims to characterize the structure of human urotensinergic peptides by CD, NMR and molecular modelling. hUII (11 aa) and its analogue URP (8 aa) are considered as the most potent vasoactive peptides known so far and are involved in various biological systems, including the cardiovascular system and tumor cell proliferation. These two peptides are endogenous ligands of a GPCR, UT, and exert common but also divergent physiological actions. In order to gain a better understanding of their biological activities, we determined the structures of three agonists (hUII4-11, URP, P5U) and one antagonist (urantide), in DPC micelles, a cellular eukaryotic mimetic membrane. For all peptides, we observed the presence of two major forms of the disulfide bridge, RHStaple and LHHook, which are known to be essential for biological activity. We showed a difference in the turn nature between agonists (type I β turn) and the antagonist (type II’ β turn). Our analyses also revealed that, in agonists and antagonist, the side chain orientations of residues F6, Y9 and more specifically W7 were different. Indeed, the indole group of D-W7 exhibited a 180° rotation. Secondly, we showed that, contrary to URP, the conformation of hUII was dependent on concentration. This selfassembly phenomenon may impact the interaction with the receptor and be responsible for the differential biological activities of hUII and URP
Zhang, Naiyu. "Cellular GPU Models to Euclidean Optimization Problems : Applications from Stereo Matching to Structured Adaptive Meshing and Traveling Salesman Problem." Thesis, Belfort-Montbéliard, 2013. http://www.theses.fr/2013BELF0215/document.
Повний текст джерелаThe work presented in this PhD studies and proposes cellular computation parallel models able to address different types of NP-hard optimization problems defined in the Euclidean space, and their implementation on the Graphics Processing Unit (GPU) platform. The goal is to allow both dealing with large size problems and provide substantial acceleration factors by massive parallelism. The field of applications concerns vehicle embedded systems for stereovision as well as transportation problems in the plane, as vehicle routing problems. The main characteristic of the cellular model is that it decomposes the plane into an appropriate number of cellular units, each responsible of a constant part of the input data, and such that each cell corresponds to a single processing unit. Hence, the number of processing units and required memory are with linear increasing relationship to the optimization problem size, which makes the model able to deal with very large size problems.The effectiveness of the proposed cellular models has been tested on the GPU parallel platform on four applications. The first application is a stereo-matching problem. It concerns color stereovision. The problem input is a stereo image pair, and the output a disparity map that represents depths in the 3D scene. The goal is to implement and compare GPU/CPU winner-takes-all local dense stereo-matching methods dealing with CFA (color filter array) image pairs. The second application focuses on the possible GPU improvements able to reach near real-time stereo-matching computation. The third and fourth applications deal with a cellular GPU implementation of the self-organizing map neural network in the plane. The third application concerns structured mesh generation according to the disparity map to allow 3D surface compressed representation. Then, the fourth application is to address large size Euclidean traveling salesman problems (TSP) with up to 33708 cities.In all applications, GPU implementations allow substantial acceleration factors over CPU versions, as the problem size increases and for similar or higher quality results. The GPU speedup factor over CPU was of 20 times faster for the CFA image pairs, but GPU computation time is about 0.2s for a small image pair from Middlebury database. The near real-time stereovision algorithm takes about 0.017s for a small image pair, which is one of the fastest records in the Middlebury benchmark with moderate quality. The structured mesh generation is evaluated on Middlebury data set to gauge the GPU acceleration factor and quality obtained. The acceleration factor for the GPU parallel self-organizing map over the CPU version, on the largest TSP problem with 33708 cities, is of 30 times faster
Wu, Jian. "INVESTIGATION OF THE RELATIONSHIP BETWEEN RNA 3D STRUCTURE AND FUNCTION USING POTATO SPINDLE TUBER VIROID (PSTVD) AS A MODEL." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565876797069284.
Повний текст джерелаZHANG, Naiyu. "Cellular GPU Models to Euclidean Optimization Problems : Applications from Stereo Matching to Structured Adaptive Meshing and Traveling Salesman Problem." Phd thesis, Université de Technologie de Belfort-Montbeliard, 2013. http://tel.archives-ouvertes.fr/tel-00982405.
Повний текст джерелаManandhar, Sandeep. "3D motion estimation and assessment in fluorescence microscopy volume sequences." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S096.
Повний текст джерелаThe thesis work deals with the computation and the assessment of 3D motion fields in 3D fluorescence microscopy image sequences. We have investigated 3D matching and variational methods for 3D flow field estimation between two consecutive volumes. For matching, we have developed two original 3D extensions of PatchMatch both involving the discrete Census similarity measure: a super-pixel based method that proceeds slice by slice, and a coarse-to-fine method directly applied to the volumes. We have also designed a protrusion segmentation method on the cell surface along with a matching stage relying on a triangular mesh-based representation. Regarding the dense estimation of 3D flow fields, we have adopted a variational approach, while exploiting the continuous Census signature of voxels in the data term. We have tested three regularization terms: L2, L1, and TV-based regularization. We have also combined the 3D PatchMatch method with the variational method to be able to handle simultaneously large and small motion magnitude. For visual assessment, we have proposed three different color-coded visualization techniques of 3D flow fields. They offer 2D summaries of the 3D flow field, respectively, slice-by-slice, with tri-planar projections, and after maximum intensity point projection. In addition, we have defined a new quantitative error measure for assessing the accuracy of the estimated flow field when no ground truth is available. It involves the angular difference between the local principal orientation of the original source volume and the corresponding one in the volume backward-warped with the 3D computed flow field. We have tested our methods on real microscopy image sequences containing MV3 melanoma cells in collagen environment. When comparing with the state-of-the-art method of Amat et al., and our 3D extension of the classical Horn-and-Schunck method, we found our proposed methods to be the best performing ones
Thouvenin, Olivier. "Optical 3D imaging of subcellular dynamics in biological cultures and tissues : applications to ophthalmology and neuroscience." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC169/document.
Повний текст джерелаThis PhD project aims to explore the relationship that might exist between the dynamic motility and mechanical behavior of different biological systems and their biochemical activity. In particular,we were interested in detecting the electromechanical coupling that may happen in active neurons, and may assist in the propagation of the action potential. With this goal in mind, we have developed two highly sensitive optical microscopes that combine one modality that detects sub-wavelength axial displacements using optical phase imaging and another modality that uses a fluorescence path. Therefore, these multimodal microscopes can combine a motility, a mechanical,a structural and a biochemical contrast at the same time. One of this system is based ona multimodal combination of full-field optical coherence tomography (FF-OCT) and allows the observation of such contrast inside thick and scattering biological tissues. The other setup provides a higher displacement sensitivity, but is limited to measurements in cell cultures. In this manuscript, we mainly discuss the development of both systems and describe the various contrastst hey can reveal. Finally, we have largely used our systems to investigate diverse functions of the eye and to look for electromechanical waves in cell cultures. The thorough description of both biological applications is also provided in the manuscript
Chamayou, Léo. "LiverPearls, une méthode de culture multicellulaire miniaturisée et à haut débit reproduisant l’environnement physiologique et la structure tridimensionnelle du foie humain." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLS005.
Повний текст джерелаInterest for new and more physiologically relevant liver models is high, particularly from pharmaceutical companies. Standard systems, like 2D culture, are indeed not enough predictive and better models are needed, either for drug candidates screening in ADME/Tox studies or for hepatic diseases modelling. To be closer to the human liver, a new model needs toreplicate liver structure and cellular composition better than the 2D. To this end, we used a micro-encapsulation technology, developed by the laboratory and based on the co-extrusion of a two-phases jet, composed of an alginate external phase and a cell-containing internal phase. This jet is then fragmented into micro-droplets and the alginate reticulated to form core-shell microcapsules. The porous alginate shell protects the cells from shear stress while letting oxygen and nutrients pass, and by preventing cell adhesion, enables the cells to self-assemble into hepatic spheroids which can bekept alive during one month, retain good functionality and can be used for high-throughput screening. This thesis focusedon using this technology to develop a next 3D liver model containing human primary hepatocytes, Kupffer cells and liver sinusoidal endothelial cells. Firstly, culture conditions for this model had to be optimized, particularly the ratio between these different cell types and the culture medium, which had to be suitable for these cell types. Then, once the culture conditions had been established, the model was characterized, structurally by immunofluorescence staining, and functionally by studying gene expression of important liver proteins, like cytochromes P450 or nuclear receptors. Enzymaticactivity, albumin and urea secretion were also studied. These capsules allow us to obtain a model able to replicate the complex interactions between these cell types and structurally closer to the human liver
Vermeulen, Pierre. "Microscopie à illumination structurée et optique adaptative pour l'imagerie de fluorescence 3D dynamique." Phd thesis, Université Paris-Diderot - Paris VII, 2012. http://pastel.archives-ouvertes.fr/pastel-00777094.
Повний текст джерелаDuarte, Campos Daniela Filipa [Verfasser], Horst [Akademischer Betreuer] Fischer, Daniela [Akademischer Betreuer] Zander, and Stefan [Akademischer Betreuer] Jockenhövel. "Cellular differentiation in 3D-bioprinted mesenchymal stem cell-loaded hydrogels with varying structural and mechanical properties / Daniela Filipa Duarte Campos ; Horst Fischer, Brita Daniela Zander, Stefan Jockenhövel." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://nbn-resolving.de/urn:nbn:de:hbz:82-rwth-2016-024801.
Повний текст джерелаDuarte, Campos Daniela Filipa [Verfasser], Horst Akademischer Betreuer] Fischer, Brita Daniela [Akademischer Betreuer] Zander, and Stefan [Akademischer Betreuer] [Jockenhövel. "Cellular differentiation in 3D-bioprinted mesenchymal stem cell-loaded hydrogels with varying structural and mechanical properties / Daniela Filipa Duarte Campos ; Horst Fischer, Brita Daniela Zander, Stefan Jockenhövel." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130326853/34.
Повний текст джерелаDuarte, Campos Daniela Filipa Verfasser], Horst [Akademischer Betreuer] Fischer, Brita Daniela [Akademischer Betreuer] Zander, and Stefan [Akademischer Betreuer] [Jockenhövel. "Cellular differentiation in 3D-bioprinted mesenchymal stem cell-loaded hydrogels with varying structural and mechanical properties / Daniela Filipa Duarte Campos ; Horst Fischer, Brita Daniela Zander, Stefan Jockenhövel." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130326853/34.
Повний текст джерелаRacine, Victor. "Quantification des dynamiques cellulaires par analyse de données de vidéo-microscopie 3D+t." Paris 6, 2006. http://www.theses.fr/2006PA066480.
Повний текст джерелаThis thesis presents several approaches aiming to analyze fluorescence microscopy images in the field of cell biology. It is essentially focused on techniques for localization and tracking of multimolecular complexes in multidimensional data (2D, 2D+t, 3D and 3D+t). The first part of this work is dedicated to the extraction and characterization of fluorescent biological structures using wavelet based segmentation. Various biological studies performed in collaboration with various research groups are detailed, such as a study about morphometric analysis of organelles of cell constrained by micro patterns or the localization of the mid1p protein in yeasts. In a second part, a tracking algorithm of labeled molecular structures is presented. It is based on the linking over time of segmented objects by minimizing the association costs by a simulated annealing technique. This method is particularly well adapted in a lot of biological situations, because it allows modeling of many events like birth, death, fusion and fission. A single molecule (mono-disperse DNA 166kbp) dynamics analysis has been made using this tracking technique in order to extract the variations of the molecular diffusion coefficient. The third part describes a set of analyzes with the goal to study the spatial and temporal localization of transport intermediates involved in the membrane trafficking tagged by chimerical GFP-Rab6A and GFP-Rab6A’ proteins. Several complementary approaches are used to extract quantitative information and to describe the underneath biological processes
Larburu, Natacha. "Etude structurale de la biogenèse de la petite sous-unité ribosomique humaine par cryo-microscopie électronique et analyse d'images." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30336/document.
Повний текст джерелаRibosome biogenesis is a complex process that requires the production and the correct assembly of the 4 rRNAs with 80 ribosomal proteins. In Human, the production of the two subunits, 40S and 60S, is initiated by the transcription of a pre-ribosomal rRNA precursor to the mature 18S, 5.8S, and 28S rRNAs by the RNA polymerase I, which is chemically modified and trimmed by endo- and exoribonuclease, in order to form the mature rRNAs. The nascent pre rRNA associated with ribosomal proteins, small ribonucleoprotein particles (snoRNP) and so called co-factors leading to the assembly of an initial 90S particle. This particle is then split into pre-40S and pre-60S pre-ribosomal particles that fallow independent maturation to form the mature subunit into the cytoplasm. Production of eukaryotic ribosomes implies the transient intervention of more than 200 associated proteins and ribonucleoprotein particles, that are absent from the mature subunits. Synthesis of ribosome, globally conserved in eukaryotes, has been principally studied in yeast. However, recent studies reveal that this process is more complex in human compared in yeast. An important bottleneck in this domain is the lack of structural data concerning the formation of intermediate ribosomal subunits to understand the function of assembly factors. Determination of the structural remodeling of pre-ribosomal particles is crucial to understand the molecular mechanism of this complex process. So I have undertaken a structural study on the assembly of the small ribosomal subunit using cryo-electron microscopy and image analysis. The goal of my thesis is to determine the 3D structures of human pre-40S particles at different maturation stages to see the structural remodeling that occurs during the biogenesis of the small ribosomal subunit. We are collaborating with the group of Pr Ulrike Kutay at ETH Zurich, who purify human pre-40S particles. The 3D structures of human pre-40S particles purified at an intermediate and late maturation stages, has been determined with a resolution of 19 and 15Å respectively. Supplementary densities, compared to the mature subunit, indicate the presence of assembly factors and show the unexpected presence of the RACK1 protein in the precursor of the human small ribosomal subunit in the cytoplasm. The comparison of the 3D structures of human pre-40S particle allows showing the structural remodeling that occur during the maturation of the small ribosomal subunit. This work provides the first 3D structure of human pre-40S particles and laid the methodological foundations for future exploration of the structural dynamics of pre-ribosomal particles
Arpón, Javier. "Statistical analysis and modeling of nuclear architecture in Arabidopsis Thaliana." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS586/document.
Повний текст джерелаEukaryotic cell nuclei contain distinct functionally or structurally defined compartments at multiple scale that present a highly ordered spatial arrangement. Several studies in plants and animals have pointed out to links between nuclear organization and genome functions. A key challenge is to identify rules according to which nuclear compartments are organized in space and to describe how these rules may vary according to physiological or experimental conditions. Spatial statistics have been rarely used for this purpose, and were generally limited to the evaluation of complete spatial randomness. In this Thesis, we develop a spatial statistical approach, which combines cytology, image analysis and spatial modeling to better understand spatial configurations inside the nucleus. Our first contribution is a methodological framework that allows to test models of spatial organization at the population level. Several spatial models have been developed and implemented, including randomness, orbital randomness, maximum regularity, territorial randomness or orbital territorial randomness of biological objects within finite 3D domains of arbitrary shape. New spatial descriptors, in combination with classical ones, are used to compare observed patterns to expected configurations under the tested models. An unbiased version of a previously published statistical test is proposed to evaluate the goodness-of-fit of spatial models over populations of observed patterns. In the second part of this Thesis, we investigate the properties of the proposed approach using simulated and real data. The robustness of the proposed approach to segmentation errors and the reliability of the spatial evaluations are examined. Besides, the basis for a method to compare spatial distributions between different experimental groups is proposed. In the last part of this work, the proposed approach is applied on A. thaliana leaf cell nuclei images to analyze the spatial distribution of chromocenters, which are dynamic and plastic heterochromatic compartments that have an important structural role in the genome. A first application was to analyze isolated and cryo-section nuclei from wild type plants. We show that chromocenters present a highly regular distribution, confirming previously published results. Using new spatial statistical descriptors, we then demonstrate objectively and quantitatively, for the first time, that chromocenters exhibit a preferentially peripheral localization. Employing a new spatial model, we then reject the hypothesis that the regular organization is explained solely by the peripheral positioning. We further demonstrate that chromocenters organization displays a close-to-maximum spatial regularity at the global scale, but not at the local one. Lastly, we use simulations to examine a model according to which chromocenters positioning is constrained by chromosome territories and by interactions with the nuclear boundary. The second application was to elucidate whether chromocenters distribution could be altered under different mutations. We analyze nuclei data from crwn and kaku mutants, which are known to affect nuclear morphology. The results suggest that these mutations impact on nuclear morphology and on heterochromatin features but do not alter the regularity of chromocenters distribution even when the relative distance to the border is affected. The genericity of the proposed framework to analyze object distributions in finite 3D domains and its expandability to add more spatial models and spatial descriptors should be of interest to decipher spatial organizations within biological systems at various scales
Lu, Biao. "Evaluation of physico-chemical properties of biorefinery-derived amphiphilic molecules and their effects on multi-scale biological models." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2218/document.
Повний текст джерелаNowadays, a wide variety of new molecules can derive from biomass. Among them, the family of sugar-based surfactants, which are considered as alternatives to fossil-based surfactants, due to their relatively high biodegradability and biocompatibility, exhibit interesting properties both in terms of their self-assembly and their ability to induce biological responses. In the study, for the purpose to analyse these properties, different methodologies have been established. In this work, physico-chemistry and cellular biology methodologies are associated to analyse the properties of pre-selected molecules characterized by gradua) structure modifications. Firstly, we have screened synthesized sugar-based surfactants according to their solubility and their ability to reduce surface tension of water. Four pre-selected molecules, with a C8 chain linked to a glucose or maltose head through an amide functional group, either under the form of carbamoyl (carbohydrate scaffold bearing the carbonyl) or alkylcarboxamide (the alkyl chain bearing the carbonyl), were then dissolved in water/ cell culture media for surface tension measurements. Their behaviors in solutions were characterized by Krafft points, Critical Micellar Concentrations or self-assembling properties through different methods. To evaluate the cytotoxic/ irritant effects of these molecules on cells and tissues, 3 in-vitro models were established: I) 2D cell culture mode! (L929 cell monolayer) II) 3D ce!! culture mode! (L929 cells embedded in collagen gel) and III) Reconstituted human epidermis (differentiated human keratinocytes). Corresponding experiments were carried out on these models with increasing complexity. Results show that the synthesized sugar-based surfactants, GlulamideC8, Glu6amideC8, Glu6amideC8' and MallamideC8 can reduce the surface tension of water solution to the came level as standard surfactants (Tween 20 and Hecameg). In the meantime, GlulamideC8, Glu6amideC8' and MallamideC8 present Iess cytotoxicity effects on L929 cells both in the monolayer model and the 3D mode! than Tween 20 and Hecameg. All synthesized and standard surfactants (GlulamideC8, Glu6amideC8, Gu6amideC8', MallamideC8, Tween 20 and Hecameg) have no significant cytotoxic/ irritant effects on reconstituted human epidermis at 1000 ig/mL after 48 h of topical application. Discussions have been made according to the results of experiments to establish possible structures/ physico-chemical properties - cytotoxicity relationships of these surfactants
Barel, Monique. "Structure et fonctions de gp 140 : le recepteur pour le fragment c3d du troisieme composant du complement et pour le virus d'epstein-barr present a la surface des lymphocytes b humains." Paris 6, 1987. http://www.theses.fr/1987PA066143.
Повний текст джерелаTaileb, Saïd. "Vers des simulations numériques prédictives des détonations gazeuses : influence de la cinétique chimique, de l’equation d’etat et des effets tridimensionnels Influence of the chemical modeling on the quenching limits of gaseous detonation waves confined by an inert layer Computation of the mean hydrodynamic structure of gaseous detonations with losses Numerical study of 3D gaseous detonations in a square channel." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2020. http://www.theses.fr/2020ESMA0012.
Повний текст джерелаThis study is part of the general framework of numerical simulations of detonations under non-ideal conditions.The configurations discussed correspond to flows encountered in industrial hazards and rotating detonation engines.Simulations are based on an inhouse code RESIDENT (REcycling mesh SImulation of DEtonations) developed at the Pprime Institute. It is based on high-order shock capturing schemes, with a MP9 interpolation scheme, a HLLC-M solver and a 3rd Runge-Kutta time integration. At first, the influence of the equation of state (EOS) on the cellular detonation structure has been studied with two EOS : Perfect gas and Noble-Abel. The numerical results have shown that new triples points are generated from the interaction of a slip line with already existing triple points. The increase of the post-shock isentropic coeffient has inhibited the appearance of these instabilities and has regularized the cell structure. This results may be important as engineering correlations are based on the cell size and regularity. Secondly, the influence of chemical modelling on the structure of the detonation and its extinction limits were studied using three kinetic models of increasing complexity : single-step, three-step chain-branching and detailed chemistry. Despite the macroscopic features are similar, the outcome of the critical height of a detonation confined by an inert layer is significantly different, highlighting the impact of the kinetics in predicting the extinction limits observed in experiments. Finally, the influence of three-dimensional effects on the dynamics of detonation was studied. Comparisons of 2-D and 3-D simulations are carried out in the case of marginal and semi-confined detonations. Despite the differences observed in the flow topology, similarities were found in the mean structure when the detonation propagation is ideal. The analysis of the total fluctuation energy revealed that entropy fluctuations are more important than pressure fluctuations. In the case of semi-confined detonation, 3-D effects manifests a smaller velocity deficit than in 2-D when the detonation propagates at the same reactive height. The velocity deficitis correlated to the ratio of the hydrodynamic thickness to the radius of curvature, despite the higher average curvature of the 3-D front
Chen, Guang-Liang, and 陳廣亮. "3D Printable Porous Shoe Midsole Design with Cellular Structures Based on Truss Optimization and Voxel Post-Processing." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/cg5yt9.
Повний текст джерела國立臺灣科技大學
機械工程系
107
Topology optimization (TO) is a method of structural optimization which widely used in many fields. The concept of TO is to get the best structure in the design domain under the volume constraints. Before additive manufacturing (AM) evolved to become a common method to produce components, the complicate topology structure is hard to be fabricated. However, AM was substantial growing in the past decades and the difficulty of topology structure fabrication had been dramatically reduced. Therefore, more and more topology structure can be used in our daily life. Now, some researcher started to use TO to design porous midsole structure. In order to calculate with high precision, the design needs amounted mesh in finite element and thus the computation task is very heavy. This research presents a fast approach of porous midsole design which is based on truss size optimization and post-processing of voxelization and gets the optimal porous-like structure. The algorithm flow starts with building the truss in the design domain and clustering the truss member by simulating each member stress with loading. Then it uses clustering optimization algorithm to find the best size of each truss member. After that, the algorithm uses Boolean operation to unite all members of the truss and 3D blur convolution to fillet the truss structure and compensate the volume error. In the final, we use two shoe lost to verify the feasibility of this methods and the results show that this is a fast and efficiency manner.
Ханыкова, Е. В., та E. V. Khanykova. "Аддитивные технологии 3d печати в производстве титановых имплантатов и испытание полученных материалов на пластическое сжатие : магистерская диссертация". Master's thesis, 2018. http://hdl.handle.net/10995/63676.
Повний текст джерелаПредметом исследования является титановый имплантат. Метод исследования состоит в приближенном решении краевой задачи методом конечных элементов в программном модуле ABAQUS. Проведен патентно-литературный поиск в области применения аддитивных технологий в производстве имплантатов. В первом разделе представлены результаты обзора. Были рассмотрены методы аддитивного производства и способы испытания пористых материалов, результаты описаны во втором разделе. Проведено описание испытания на осадку пористого имплантата и конечно-элементное моделирование процесса осадки ячеистого материала. В результате чего была построена схема распределения параметров напряженно-деформированного состояния, которая позволяет оценить опасные сечения с позиции разрушения конструкции. Полученные данные могут быть применены в построении архитектуры набора элементарных ячеек с описанием напряженно-деформированного состояния.
Pilarski, Patrick Michael. "Computational analysis of wide-angle light scattering from single cells." Phd thesis, 2009. http://hdl.handle.net/10048/774.
Повний текст джерелаTitle from PDF file main screen (viewed on Apr. 1, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Electrical and Computer Engineering, University of Alberta. Includes bibliographical references.