Дисертації з теми "Protéines – Séparation – Simulation par ordinateur"
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Irankunda, Rachel. "Nickel Chelating Peptides & Chromatography : From Peptides Separation Simulation up to their Antioxidant Activities - related Applications." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0213.
Metal-Chelating Peptides (MCPs), from protein hydrolysates, present various applications in nutrition, pharmacy, cosmetic etc. Yet, the empirical approach generally used to discover bioactive peptides from hydrolysates is time consuming and expensive due to many steps of fractionation, separation and biological activities evaluation. Thus, this PhD aimed to develop a novel approach for MCPs separation prediction using chromatography modelling and simulation based on the analogy between Immobilized Metal ion Affinity Chromatography (IMAC) and Surface Plasmon Resonance (SPR). For the first time, the SPR-IMAC analogy was experimentally investigated on 22 peptides and 70% of them validated this analogy, since peptides well retained in IMAC were also endowed with a good affinity for Ni2+ in SPR. In the second time, peptides with high affinity for Ni2+ (i.e low dissociation constant KD in SPR and a high retention time in IMAC) were used to study the modelling and simulation of peptide concentration profiles at the column outlet in IMAC. Since knowledge of adsorption isotherms was required to perform simulation, it was necessary to develop a methodology for predicting Langmuir isotherm parameters in IMAC from SPR data. The validity of simulation was evaluated by comparing experimental and simulated retention times that should be close for reliable prediction. Therefore, several approaches were evaluated to determine Langmuir sorption parameters, the most interesting one introduces a correction factor on the maximum adsorption capacity qmax alone, assuming that the affinity of peptides for immobilized Ni2+ did not change depending on the technology used (SPR vs. IMAC), thus affinity constant KA was not modified. Meanwhile, industrial application of MCPs and hydrolysates were studied. First, pea protein hydrolysates were produced by either Alcalase® followed by Flavourzyme® (Alc+Flav≤1kDa) or Protamex® followed by Flavourzyme® (Prot+Flav≤1kDa). SwitchSENSE® technology evidences the presence of Ni2+ chelating peptides and antioxidants tests showed that Prot+Flav≤1kDa has higher radical scavenging and reducing power, related to its higher degree of hydrolysis and small-size peptides quantity. Secondly, pea hydrolysates and MCPs were investigated for their ability to inhibit the lipid oxidation in emulsions. They slowed down lipid oxidation through chelation of prooxidant (metals such as Fe2+) reducing primary and secondary oxidation products responsible of deterioration of lipid containing products. Thus, pea hydrolysates and MCPs could be used as antioxidants in food and cosmetic products, as alternative to chemicals such as EDTA, BHT and TBHQ
Chlendi, Mohamed. "Séparation de gaz par adsorption modulée en pression." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL048N.
Joulia, Xavier. "Simulation des procédés chimiques en régime permanent : formulation et convergence." Toulouse, INPT, 1987. http://www.theses.fr/1987INPT021G.
Hénin, Jérôme. "Simulations moléculaires d'événements rares dans les systèmes biologiques membranaires." Nancy 1, 2006. http://www.theses.fr/2006NAN10007.
Slow or non spontaneously occurring processes involving biological macromolecules may still be studied through molecular dynamics simulations, provided that an algorithm promotes the exploration of a well–chosen reaction coordinate by the system. We implemented such an algorithm in the NAMD program, designed for large–scale simulations of biomolecular systems. We can then investigate the folding of peptides into alpha–helices, the recognition and association of proteins inside the membrane, as well as the specific transport of a small molecule, glycerol, by a bacterial transmembrane channel
Henry, Daniel. "Simulation numérique 3D des mouvements de convection thermosolutale d'un mélange binaire : étude paramétrique de l'influence de la convection sur la séparation des espèces du mélange par effet Soret, dans un cylindre incliné." Lyon 1, 1986. http://www.theses.fr/1986LYO10029.
Rottereau, Manuel. "Agrégation, percolation et séparation de phase d'une assemblée de sphères dures browniennes adhésives : approche par simulation hors réseau." Le Mans, 2005. http://cyberdoc.univ-lemans.fr/theses/2005/2005LEMA1003.pdf.
The complex fluids form a class of materials exhibiting a large originality in their static and dynamic properties which results from the chemical structure of the constituting elementary particles and their spatial organization in particular on mesoscopic scales. These systems often involve phenomena of aggregation, gelation and/or phase separation due to the interactions between their constituents. The objective of this thesis is to understand and model the formation of these structures and their way of filling the space by monitoring these processes by computer simulations. These simulations are based on off-lattice hard spheres models which can mimic for example an assembly of spherical micelles in attractive or repulsive interactions
Chouikhi, Najib. "Production de biométhane à partir de biogaz par technologie de séparation par adsorption PSA : optimisation numérique par approche multi-échelle." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST043.
As global interest in renewable energy intensifies, biogas production continues to grow as a clean, renewable source. Pressure Swing Adsorption (PSA) is considered as one of the most interesting technologies for the valorization of biogas into biomethane. The great flexibility of the PSA process is linked in some way to its complexity with several design and operating parameters which control the performance of the separation unit. The identification of these parameters by an experimental approach is practically impossible. A numerical study stage is essential for sizing the unit, designing the pressure cycle and identifying the optimal operating conditions before any experimental test.The general objective of the thesis was focused on the development of simulation tools for a biomethane purification process using PSA technology.In a first stage, a simulation based on one-dimensional non-isothermal dynamic model, where the intragranular mass transfer kinetics was modelled using a double driving force (bi-LDF) approximation, was implemented. A carbon molecular sieve (CMS-3K) was selected. This adsorbent ensures a high kinetic selectivity of carbon dioxide with respect to methane (CH4). The optimized cycle, composed of five columns and fifteen steps including three equalization steps and a purge gas recycling allowed a CH4 recovery of 92% with a moderate specific energy consumption of 0.35 kWh/Nm3 , at the same time respecting the grid injection specifications (97% CH4 purity ). The performance obtained is thus compatible with industrial operation.The development of a multidimensional (3D) and multi-scale (column/grain/crystal) numerical model would serve to evaluate the limits of the assumptions and correlations used in usual simulators. The first step consists in simulating the gas flow in an adsorbent bed having a reaslistic stacking.. Thus, an inert packed bed was numerically generated by DEM calculation (discrete element modeling) for a column of laboratory size. The use of OpenFOAM (CFD software) allowed to calculate the three-dimensional tracer gas flow in the column. In parallel an experimental study of the breakthrough curves was carried out using a bed having the same dimensions and characteristics. The breakthrough times and the dispersion-diffusion coefficients calculated and measured were similar. However the simulation showed some divergences in the concentration of the tracer locally in the column, due to difficulties in meshing. The next step will consist in taking into account grain-fluid interactions by considering porous adsorbent grains
Rhioui, Saloua. "Nouvelles approches pour la séparation de sources." Toulon, 2006. http://www.theses.fr/2006TOUL0020.
The blind source separation is widely studied problem in the community of signal processing because of its numerous potential applications in telecommunications, biomedical, geophysics, speech processing, image processing, radar, sonar, etc. This partly explains the great popularity of this set of themes. This thesis proposes new approaches for random sources separation. Two major problems are tackled. The first relates to the instantaneous mixture separation of cyclostationnary sources and the second, more consequent, adresses the problem of the separation of convolutive mixtures stationary signals. He develop new criteria and algorithms based on the use of various orders statistics. More precisely we propose a separation method based on the decomposition of a linear operator combined with a classification method. The performances are compared by computer simulations with PARAFAC decomposition method. Then we are interested in new contrast functions using reference signals within the framework of convolutive mixtures. A MISO contrast is proposed whose great advantage is to allow a quadratic optimization. Then MIMO contrasts are proposed generalizing the existing contrasts in the literature
Youssef, Siham. "Conception de colonnes de rectification complexes par une méthode short-cut : application aux cascades de séparation." Toulouse, INPT, 1989. http://www.theses.fr/1989INPT042G.
Achir, Samira. "Etude des mécanismes de stabilisation des protéines par spectroscopie Raman et dynamique moléculaire." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10022/document.
The mechanisms of protein stabilization in solution and dry state have been investigated in this thesis. New therapeutic approaches are developing from many therapeutic biomolecules related to advances in recombinant DNA technology. Although we are not able to use them because of their low stability. The latter is improved in the dry state albeit freeze-drying gets a source of stress for many proteins. This work has mainly focused on the stability of model proteins, by in-situ Raman micro-spectroscopy during freeze-drying. The analysis identified the origin and the process of denaturation and the structural transformations of the inherent protein freeze-drying. Raman mapping was implemented at different stages of drying cycle, leading to the description of the protein/solvent/co-solvent interactions and decrypting the protein stabilizing mechanisms during the whole freeze-drying process. The protein stability was also analyzed during accelerated aging, by using several biopreservers. It revealed that the bioprotective efficiency of trehalose is enhanced by adding a small amount of glycerol. Molecular dynamics simulations were also carried out on trehalose-glycerol glassy matrices and the plasticizing / anti- plasticizing effects of the residual water were studied
Santini, Sébastien. "Flexibilité et changements topologiques de la protéine prion et du peptide β-amyloi͏̈de d'Alzheimer par simulations numériques". Aix-Marseille 1, 2004. http://www.theses.fr/2004AIX11029.
Lelimousin, Mickaël. "Traitement des interactions électrostatiques dans les systèmes moléculaires : étude par simulation numérique de protéines fluorescentes." Grenoble 1, 2009. http://www.theses.fr/2009GRE10075.
Reaction processes in biological systems are henceforth modeled by more and more advanced quantum mechanics (QM) methods coupled with force fields of molecular mechanics (MM). This improvement involves problems in the usual treatment of the QM/MM electrostatic interactions. In the first part of the thesis, we have developed a more consistent approach for the calculation of these interactions. In a second part, we have applied some computational methods to fluorescent proteins. A molecular dynamics study has revealed weak van der Waals interactions which control the improved fluorescence for Cerulean, a variant of ECFP (Enhanced Cyan Fluorescent Protein). We have also investigated the photoconversion mechanism of the fluorescent protein EosFP using predictive QM/MM potentials for excited states. Finally, thermodynamic stability of different structures in IrisFP has been estimated. These molecular modeling studies improve our knowledge about fluorescent proteins in order to develop more advanced highlighters for cell imaging
Salmon, Joseph. "Agrégation d'estimateurs et méthodes à patchs pour le débruitage d'images numériques." Paris 7, 2010. http://www.theses.fr/2010PA077195.
The problem studied in this thesis is denoising images corrupted by additive Gaussian white noise. The methods we use to get a better picture from a noisy one, are based on patches and are variations of the well known Non-Local Means. The contributions of this thesis are both practical and theoretical. First, we study precisely the influence of various parameters of the method. We highlight a limit observed on the treatment of edges by the usual patches based methods. Then, we give a better method to get pixel estimates by combining information from patches estimates. From a theoretical point of view we provide a non-asymptotic control of our estimators. The results proved are oracle inequalities, holding for a restrictive class of estimators, close to the form of the Non-Local Means estimetes. The techniques we use are based on aggregation of estimators, and more precisely on exponentially weighed aggregates. Typically, the last method requires a measure of the risk, that is obtained through a unbiased estimator of the risk. A common way to get such a mesure is to use the Stein Unbiased Risk Estimate (SURE). The denoising methods studied are analyzed numerically by simulations
Paul, Nicodème. "Développement de nouvelles applications en criblage virtuel." Strasbourg 1, 2003. http://www.theses.fr/2003STR13193.
Based on molecular docking, virtual screening or in silico screening becomes of increasing interest in the pharmaceutical industry. In this study, we propose ConsDock a consensus docking program that takes advantage of three widely used docking tools Dock, Gold and FlexX. ConsDock significantly outperforms single docking with respect to the docking accuracy of the top-ranked pose. Then, for inverse screening purpose, we develop a protein database based on the Protein data Bank (sc-PDB). This database has been used to recover target of known ligands by using an in-house inverse screening process based on Gold. At last, as we were interested in developing activated models of G Protein-Coupled Receptors or GPCRs, we present a simulation process of ligand-based GPCR folding. The simulation is performed by genetic algorithms. By using a GPCR and a ligand, the algorithm tries to find stable conformations of GPCR by rotating and translating helices. Movement is performed according experimental observations. We tested the method on the X-ray structure of rhodopsin complexed with the cis-retinal. We got some good results when used specific genetic operators for a sufficient number of generations
Faiget, Laurent. "Séparation de l'influence du local et de l'enceinte pour la prévision de l'intelligibilité dans des conditions d'écoute difficiles." Toulouse 3, 1997. http://www.theses.fr/1997TOU30151.
Druart, Karen. "Défis algorithmiques pour les simulations biomoléculaires et la conception de protéines." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX080/document.
Computational protein design is a method to modify proteins and obtain new properties, using their 3D structure and molecular modelling. To make the method more predictive, the models need continued improvement. In this thesis, we addressed the problem of explicitly representing the flexibility of the protein backbone. We developed a "multi-state" design approach, based on a small library of backbone conformations, defined ahead of time. In a Monte Carlo framework, given the rugged protein energy landscape, large backbone motions can only be accepted if precautions are taken. Thus, to explore these conformations, along with sidechain mutations and motions, we have introduced a new type of Monte Carlo move. The move is a "hybrid" one, where the backbone changes its conformation, then a short Monte Carlo relaxation of the sidechains is done, followed by an acceptation test. To obtain a Boltzmann sampling of states, the acceptation probability should have a specific form, which involves a path integral that is difficult to calculate. Two approximate forms are explored: the first is based on a single relaxation path, or "generating path" (Single Path Approximation or SPA). The second is more complex and relies on a collection of paths, obtained by shuffling the elementary steps of the generating path (Permuted Path Approximation or PPA). These approximations are tested in depth and compared on two proteins. Free energy differences between the backbone conformations are computed using three different approaches, which move the system reversibly from one conformation to another, but follow very different routes. Good agreement is obtained between the methods and a wide range of parameterizations, indicating that the free energy behaves as a state function, as it should, and strongly suggesting that Boltzmann sampling is verified. The sampling method is applied to the tyrosyl-tRNA synthetase enzyme, allowing us to identify sequences that prefer either an open or a closed conformation of an active site loop, so that in principle we can control, or design the loop conformation. Finally, we describe preliminary work to make the protein backbone fully flexible, moving within a continuous and not a discrete space. This new conformational space requires a complete reorganization of the energy calculation and Monte Carlo simulation scheme, increases simulation cost substantially, and requires a much more aggressive parallelization of our software
Ribault, Judicaël. "Reuse and Scalability in Modeling and Simulation Software Engineering." Phd thesis, Université de Nice Sophia-Antipolis, 2011. http://tel.archives-ouvertes.fr/tel-00604014.
Guifo, Fodjo A. Yvan. "Séparation des préoccupations dans les modèles compartimentaux étendus." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS262.
Mathematical modeling and computer simulation have very often contributed to improving our understanding, prediction, and decision making in the face of epidemics. However, a problem that is often encountered in the development and implementation of epidemiological models is the mixing of different aspects of the model. Indeed, epidemiological models become more and more complex as new concerns are taken into account (age, gender, spatial heterogeneity, containment or vaccination policies, etc.). These aspects, which are usually intertwined, make models difficult to extend, modify or reuse. In mathematical modeling applied to epidemiology, two main approaches are considered. The first one, the "compartmental models", has proven to be robust and provides fairly good results for many diseases. However, it does not take into account some sources of heterogeneity. The second approach, based on "contact networks", has proven to be intuitive to represent contacts between individuals and brings very good results concerning the prediction of epidemics. However, this approach requires more effort during the implementation. A solution to this problem has been proposed: Kendrick. It is a modeling and simulation tool and approach that has shown promising results in separating epidemiological concerns, by defining them as stochastic automata (continuous time markov chain), which can then be combined using an associative and pseudo commutative tensor sum operator. However, a significant limitation of this approach is its restricted application to compartmental models. Taking into account the particularities and shortcomings of each approach, in this research work, we propose a combined approach between compartmental models and contact network models. The aim is to generalize the Kendrick approach to take into account certain aspects of contact networks in order to improve the predictive quality of models with significant heterogeneity in the structure of the contacts, while maintaining the simplicity of compartmental models. To achieve this, this extension of compartmental models is made possible by applying the infection force formalism of Bansal et al (2007) and the behavioral Template Method Design Pattern. The result is an approach that is easy to define, analyze and simulate. We validated this approach on different techniques to generalize compartmental models. Simulation results showed that our approach succeeds in capturing the aspects of contact network models within the compartmental framework while improving the prediction quality of the Kendrick tool and does not deviate from a typical simulation approach on a contact network model
Lanrezac, André. "Interprétation de données expérimentales par simulation et visualisation moléculaire interactive." Electronic Thesis or Diss., Université Paris Cité, 2023. http://www.theses.fr/2023UNIP7133.
The goal of Interactive Molecular Simulations (IMS) is to observe the conformational dynamics of a molecular simulation in real-time. Instant visual feedback enables informative monitoring and observation of structural changes imposed by the user's manipulation of the IMS. I conducted an in-depth study of knowledge to gather and synthesize all the research that has developed IMS. Interactive Molecular Dynamics (IMD) is one of the first IMS protocols that laid the foundation for the development of this approach. My thesis laboratory was inspired by IMD to develop the BioSpring simulation engine based on the elastic network model. This model allows for the simulation of the flexibility of large biomolecular ensembles, potentially revealing long-timescale changes that would not be easily captured by molecular dynamics. This simulation engine, along with the UnityMol visualization software, developed through the Unity3D game engine, and linked by the MDDriver communication interface, has been extended to converge towards a complete software suite. The goal is to provide an experimenter, whether an expert or novice, with a complete toolbox for modeling, displaying, and interactively controlling all parameters of a simulation. The particular implementation of such a protocol, based on formalized and extensible communication between the different components, was designed to easily integrate new possibilities for interactive manipulation and sets of experimental data that will be added to the restraints imposed on the simulation. Therefore, the user can manipulate the molecule of interest under the control of biophysical properties integrated into the simulated model, while also having the ability to dynamically adjust simulation parameters. Furthermore, one of the initial objectives of this thesis was to integrate the management of ambiguous interaction constraints from the HADDOCK biomolecular docking software directly into UnityMol, making it possible to use these same restraints with a variety of simulation engines. A primary focus of this research was to develop a fast and interactive protein positioning algorithm in implicit membranes using a model called the Integrative Membrane Protein and Lipid Association Method (IMPALA), developed by Robert Brasseur's team in 1998. The first step was to conduct an in-depth search of the conditions under which the experiments were performed at the time to verify the method and validate our own implementation. We will see that this opens up interesting questions about how scientific experiments can be reproduced. The final step that concluded this thesis was the development of a new universal lipid-protein interaction method, UNILIPID, which is an interactive protein incorporation model in implicit membranes. It is independent of the representation scale and can be applied at the all-atom, coarse-grain, or grain-by-grain level. The latest Martini3 representation, as well as a Monte Carlo sampling method and rigid body dynamics simulation, have been specially integrated into the method, in addition to various system preparation tools. Furthermore, UNILIPID is a versatile approach that precisely reproduces experimental hydrophobicity terms for each amino acid. In addition to simple implicit membranes, I will describe an analytical implementation of double membranes as well as a generalization to arbitrarily shaped membranes, both of which rely on novel applications
Hervy, Jordan. "Modélisation de l'interaction dynamique protéines Tau - microtubules." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY062/document.
Alzheimer’s disease, some frontotemporal dementias such as the Pick’s disease are examples of neurodegenerative diseases called "Tauopathies" which are characterized by the presence of intracellular aggregates of Tau-proteins in the brain of patients. The formation of such aggregates would result from the loss of the normal functions of the Tau-proteins to properly organize the microtubule network within the axon ; which leads to a progressive loss of microtubule’s mass within the axons, the disorganization of the axonal transport and at the end, the cell death. To understand the Tauopathies, we have to understand :- the dynamic of microtubules which is controlled by the mechanisms of the dynamic instability in which microtubules switch between a phase of growth (polymerization of GTP) and a phase of shrinkage (dissociation of GDP)- the interaction between Tau-proteins and microtubules which play an important role in the polymerization, stabilization and spatial organization of microtubules within the axonal network.The objective of this work is to build and consolidate the blocks in order to go to precise modeling of the interaction of microtubules with a dynamic population of Tau-proteins. To this purpose, two problems were considered : (i) the intrinsic dynamic of microtubules (i.e., in absence of Tau-proteins) and (ii) the interaction between Tau-proteins and a stabilized-microtubules (i.e., in absence of dynamic instability)In order to this, the work has been done according to two approaches :- Theoretical : development of mathematical models describing the different process.- Simulation : development of Monte-Carlo programs (under Matlab)The main results have been organized in two main parts :1) Development of a mesoscopic model describing the dynamic instability of microtubules at the scale of the tubulin. This model describes the non-Markovian dynamic of microtubules and the characteristics are compatible with the experimental observations.2) Development of a model describing the dynamical decoration of a microtubule by a population of Tau-proteins. The characteristics of the model are based, for the construction, and compatible with the experimental observations
Cinar, Éric. "Structure et dynamique dans les solutions aqueuses d'urée et d'acétone : étude par simulation de dynamique moléculaire." Lille 1, 2006. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2006/50376_2006_164.pdf.
Chaouchi, Chahinez. "Méthodes de séparation aveugle de sources non linéaires, étude du modèle quadratique 2X2." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1375/.
This thesis presents blind source separation (BSS) methods for a particular model of mixture, the quadratic one. The first part presents the separating structure (basic and extended versions). The equilibrium points of the structure and their local stability are then studied. We propose two methods of BSS. The first method uses the cumulants and the second is based on a maximum likelihood approach. We validate our results by numerical tests
Noël, Marilyne. "Influence de la température et des hautes pressions hydrostatiques sur l'activité et la stabilité d'enzymes en présence ou non d'additifs." Toulouse, INSA, 2001. http://www.theses.fr/2001ISAT0018.
The thermal (40-60ʿC) or hyperbaric (300-500MPa) stability of the lipase of Rhizomucor miehei was studied. The kinetics of inactivation obtained allowed the kinetic and thermodynamic parameters related to the irreversible deactivation of this lipase to be determined. The use of a model led to the validation of these parameters. This study was supplemented by observations in fluorescence spectrophotometry which confirmed the existence of two different mechanisms at the molecular level, during the deactivation of the enzyme by these two agents. The combination of the effects of temperature and pressure made it possible to highlight a protective effect of the moderate pressures (0,1-350 MPa) against the thermal deactivation of lipase, and a synergistic action of the pressure and the low temperatures. Additives (salts and polyhydric alcohol's), allowed the half-life of lipase to be increased during hyperbaric (25 times) or thermal (500 times) processing in a spectacular way. A classification of polyhydric alcohol's according to their protective effect could be carried out. This classification was correlated by differential scanning microcalorimetry experiments. The comparison of the results obtained by these two approaches shown that enzyme activity and conformational stability is not dependent. A study of the combined effects of the temperature, pressure and polyhydric alcohol's, showed that the polyhydric alcohol's are protective agents and their efficiency depends on the total number of hydroxyls groups brought in the medium, as well as of the denaturing process intensity inflicted with protein
Siangsanun, Vorasiri. "Hybrid process : hydrocyclone, coagulation, floculation and flotation for water treatment process." Thesis, Toulouse, INSA, 2010. http://www.theses.fr/2010ISAT0019/document.
The aim of this study is to develop a hybrid process which combines withcoagulation, floculation and flotation process in a hydroclone for water treatmentprocess. The development is for characterization the hydrodynamics of this process andto find the optimum condition for water treatment process.The hydrodynamics characterization study is carried out by the numericalsimulation (Computational Fluid Dynamics) and experimental work by Dopplerultrasound velocimetry technique to study the hydrodynamics for the further research.The results are used for validating the oil droplet experimental technique and to be thebasis knowledge to explain the phenomena in the hybrid process. Laser diffractiontechnique is involved for determining the micro bubbles size and also study on theparameter affects to the size. The experimental work of a developed hybrid pilot plant is studied with synthesisraw water and natural river water. The objective of this study is to apply this hybridprocess for the water treatment. The parameters have been varied in many operatingconditions to indicate the separation and the water treatment phenomena such as rawwater characteristic, coagulant - floculant type and concentration, air fraction and inletflow rate
Folch, Benjamin. "Etude bioinformatique de la stabilité thermique des protéines: conception de potentiels statistiques dépendant de la température et développement d'approches prédictives." Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210106.
La première partie a pour objectif l’identification des facteurs de séquence et de structure (e.g. fréquence de ponts salins, d’interactions cation-{pi}) responsables des différentes stabilités thermiques de protéines homologues au sein de huit familles (chapitre 2). La spécificité de chaque famille ne nous a pas permis de généraliser l’impact de ces différents facteurs sur la stabilité thermique des protéines. Cependant, cette approche nous a permis de constater la multitude de stratégies différentes suivies par les protéines pour atteindre une plus grande thermostabilité.
La deuxième partie concerne le développement d’une approche originale pour évaluer l’influence de la température sur la contribution de différents types d’interactions à l’énergie libre de repliement des protéines (chapitres 3 et 4). Cette approche repose sur la dérivation de potentiels statistiques à partir d’ensembles de protéines de thermostabilité moyenne distincte. Nous avons d’une part collecté le plus grand nombre possible de protéines de structure et de Tm déterminées expérimentalement, et d’autre part développé des potentiels tenant compte de l’adaptation des protéines aux températures extrêmes au cours de leur évolution. Cette méthode originale a mis en évidence la dépendance en la température d’interactions protéiques tels les ponts salins, les interactions cation-{pi}, certains empilements hydrophobes .Elle nous a en outre permis de mettre le doigt sur l’importance de considérer la dépendance en la température non seulement des interactions attractives mais également des interactions répulsives, ainsi que sur l’importance de décrire la résistance thermique par la Tm plutôt que la Tenv, température de l’environnement de l’organisme dont elle provient (chapitre 5).
La dernière partie de cette thèse concerne l’utilisation des profils énergétiques dans un but prédictif. Tout d’abord, nous avons développé un logiciel bioinformatique pour prédire la thermostabilité d’une protéine sur la base de la thermostabilité de protéines homologues. Cet outil s’est avéré prometteur après l’avoir testé sur huit familles de protéines homologues. Nous avons également développé un deuxième outil bioinformatique pour prédire les changements de thermostabilité d’une protéine engendrés par l’introduction d’une mutation ponctuelle, en s’inspirant d’un logiciel de prédiction des changements de stabilité thermodynamique des protéines développé au sein de notre équipe de recherche. Ce deuxième algorithme de prédiction repose sur le développement d’une grande base de données de mutants caractérisés expérimentalement, d’une combinaison linéaire de potentiels pour évaluer la Tm, et d’un réseau de neurones pour identifier les coefficients de la combinaison. Les prédictions générées par notre logiciel ont été comparées à celles obtenues via la corrélation qui existe entre stabilités thermique et thermodynamique, et se sont avérées plus fiables.
Les travaux décrits dans notre thèse, et en particulier le développement de potentiels statistiques dépendant de la température, constituent une nouvelle approche très prometteuse pour comprendre et prédire la thermostabilité des protéines. En outre, nos travaux de recherche ont permis de développer une méthodologie qui pourra être adaptée à l’étude et à la prédiction d’autres propriétés physico chimiques des protéines comme leur solubilité, leur stabilité vis à vis de l’acidité, de la pression, de la salinité .lorsque suffisamment de données expérimentales seront disponibles.
Doctorat en Sciences agronomiques et ingénierie biologique
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Rudwill, Floriane. "Conséquences d’une simulation d’impesanteur de 21 jours chez l’homme sur le métabolisme des lipides et effets d’une supplémentation en protéines testée comme contremesure." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAJ009/document.
During 21 days of simulated microgravity, the development of several metabolic alterations has been studied: a low-grade inflammation and an alteration of insulin sensitivity and lipid metabolism. Known for their positive effect on metabolism, whey proteins supplementation combined with alkaline salts have also been tested. At the opposite of previous studies, no inflammation, nor lipid metabolism alterations have clearly been described. Nevertheless, a decrease in carbohydrates oxidation in favor of lipids is observed, suggesting the development of insulin insensitivity. Our data suggest that it may be possible to prevent the metabolic disorders associated with severe physical inactivity by anisocaloric replacement of lipids by proteins in the diet, along with a protein intake of 1.2g/kg/day and tight control of energy balance by adjusting energy intake
Bertrand, Carl. "Modélisation de la séparation magnétique de basse intensité sur tambours rotatifs : enrichissement du minerai Havre Saint-Pierre de Rio Tinto, Fer et Titane." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27756/27756.pdf.
Malod-Dognin, Noël. "La comparaison structurale des protéines : de la maximisation du recouvrement de cartes de contacts à l'alignement basé sur les distances." Phd thesis, Université Rennes 1, 2010. http://tel.archives-ouvertes.fr/tel-00509142.
Sirota, Leite Fernanda. "Role of the amino acid sequences in domain swapping of the B1 domain of protein G by computation analysis." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210657.
The stability of the wt and quadruple mutant GB1 monomers was assessed using the software DESIGNER, a fully automatic procedure that selects amino acid sequences likely to stabilize a given backbone structure (Wernisch et al. 2000). Results suggest that 3 of the mutations (L5V, F30V, A34F) have a destabilizing effect. The first mutation (L5V) forms destabilizing interactions with surrounding residues, while the second (F30V) is engaged in unfavorable interactions with the protein backbone, consequently causing local strain. Although the A34F substitution itself is found to contribute favorably to the stability of the monomer, this is achieved only at the expense of forcing the wild type W43 into a highly strained conformation concomitant with the formation of unfavorable interactions with both W43 and V54.
Finally, we also provide evidence that A34F mutation stabilizes the swapped dimer structure. Although we were unable to perform detailed protein design calculations on the dimer, due to the lower accuracy of the model, inspection of its 3D structure reveals that the 34F side chains pack against one another in the core of the swapped structure, thereby forming extensive non-native interactions that have no counterparts in the individual monomers. Their replacement by the much smaller Ala residue is suggested to be significantly destabilizing by creating a large internal cavity, a phenomenon, well known to be destabilizing in other proteins. Our analysis hence proposes that the A34F mutation plays a dual role, that of destabilizing the GB1 monomer structure while stabilizing the swapped dimer conformation.
In addition to the above study, molecular dynamics simulations of the wild type and modeled quadruple mutant GB1 structures were carried out at room and elevated temperatures (450 K) in order to sample the conformational landscape of the protein near its native monomeric state, and to characterize the deformations that occur during early unfolding. This part of the study was aimed at investigating the influence of the amino acid sequence on the conformational properties of the GB1 monomer and the possible link between these properties and the swapping process. Analysis of the room temperature simulations indicates that the mutant GB1 monomer fluctuates more than its wild type counter part. In addition, we find that the C-terminal beta-hairpin is pushed away from the remainder of the structure, in agreement with the fact that this hairpin is the structural element that is exchanged upon domain swapping. The simulations at 450 K reveal that the mutant protein unfolds more readily than the wt, in agreement with its decreased stability. Also, among the regions that unfold early is the alpha-helix C-terminus, where 2 out of the 4 mutations reside. NMR experiments by our collaborators have shown this region to display increased flexibility in the monomeric state of the quadruple mutant.
Our atomic scale investigation has thus provided insights into how sequence modifications can foster domain swapping of GB1. Our findings indicate that the role of the amino acid substitutions is to decrease the stability of individual monomers while at the same time increase the stability of the swapped dimer, through the formation of non-native interactions. Both roles cooperate to foster swapping.
Doctorat en sciences, Spécialisation biologie moléculaire
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Ballivian, Renaud. "Étude de complexes non-covalents et de polymères organiques par couplage entre la spectrométrie de masse et la mobilité ionique." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10219.
Knowing the structure of non-covalent complexes is essential to understand many biological processes. The first step is the characterization of the interactions leading to the adoption of a functional tridimensional structure by a multimeric assembly. The second step consists of underlining the structural modifications induced by the complexation, and their influence on the system’s function. The Ion Mobility/Mass Spectrometry (IM/MS) is a gas-phase method that is used to separate ions according to their geometry and their masse-to-charge ratio. IM/MS also provides insights on their intrinsic properties, by measuring their collision cross sections. Using this method, we have studied the structure of three different non-covalent complexes: the aggregation of tannins on the human salivary protein IB-5, the fixation of a small ligand (Ac2KAA) on vancomycin, and the complexation between metallic cations and poly-lactid polymers. The evolution of the collision cross-sections as a function of the size of the system or the complexation state clearly shows structural transitions. Moreover, combined with molecular modeling or laser spectroscopy, the IM/MS technique reveals to be a powerful tool to characterize the relevant interactions in such systems. This work proves that IM/MS, besides a powerful analytical aspect, can also be used in global studies that involve several structural methods to resolve the structure of large multimeric assemblies
Gillet, Natacha. "Simulations Numériques de Transferts Interdépendants d’Electrons et de Protons dans les Protéines." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112159/document.
Redox processes involving organic molecules are ubiquitous in proteins. They generally imply global reactions such as Proton Coupled Electron Transfers, hydrogen atom or hydride transfers which can be decomposed into both electrons and proton transfers. Kinetic and thermodynamic information leads to a better understanding of these mechanisms. However, experiments are often limited to a milli- or microsecond timescales. We present here numerical simulations allowing modeling at shorter timescales (femto, pico or nanosecond) to complete experimental data. Many numerical methods combine quantum description (QM) of the active center and classical description (MM) of the environment to describe redox transformations into biological media. Molecular dynamics (MD) simulations allowed a conformational sampling of the global system. Nevertheless, depending on their level of description of the QM part, the methods can cost more or less CPU time to get a good conformational sampling. In this thesis, we have studied different redox mechanisms involving both proton and electron transfers with a particular care paid to the balance between quality of the electronic description and of conformational sampling. For each mechanism, the coupled proton and electron transfers are investigated differently. This manuscript thus falls into three parts: i) the evaluation of the redox potentials quinone derivatives ; ii) the mechanistic description of the L-lactate oxidation into pyruvate in the flavocytochrome b2 enzyme; iii) decomposition of the formal hydride transfer occurring between two flavins in EmoB protein. A QM+MM scheme is chosen to evaluate redox potential of quinone cofactors: the electronic behavior is described at DFT level in gas phase while classical MDs provide a large conformational sampling of the molecule and its environment. Deprotonation and oxidation free energies are estimated by applying the linear response approximation (LRA). We finally get a theoretical value of the redox potential for different quinocofactors in water and a calibration curve of these theoretical results in function of experimental data. This curve allowed predictions of quinone redox potentials in water with a good accuracy (less than 0.1 eV). We also try our method on the MADH protein containing a Tryptophan Tryptophilquinone cofactor. However, because of great fluctuations of the environment, the LRA is not suitable for this system. This underlines the limits of our methodology. The oxidation of L-lactate to pyruvate is described by free energy surfaces obtained at AM1/MM level. Biased MDs provide the AM1/MM profile which is then corrected at DFT level. Several reactions pathways have been noticed. They consist in sequential or concerted transfers of a proton from L-lactate to a histidine and a hydride from L-lactate to a flavin cofactor. The coupling between the two transfers depends on the conformation of the active site or on the mutations. The obtained surfaces fit qualitatively the experimental data but the theoretical activation barriers are too high. Other simulations must be explored: different methods, other mechanism... Finally, a combination of long classical MDs and constrained DFT (cDFT)/MM are employed to decompose a hydride transfer between two flavins into one hydrogen atom and one electron transfer. cDFT methodology allow us to describe diabatic states associated to the electron transfer during the hydrogen atom transfer. Applying the LRA, we can build parabola of the diabatic and determine the sequence of the two transfers. The comparison of our results in the EmoB protein or in aqueous medium shows that the protein allows the electron transfer only if the hydrogen atom transfer is happening. By this way, no semi-reduced flavin is created
Cregut, David. "Application de la modélisation moléculaire à l'étude stsructurale de la tropomyosine et des annexines : une approche complémentaire de l'expérience." Montpellier 2, 1995. http://www.theses.fr/1995MON20026.
Wang, Guan. "Roles of substrate rigidity and composition in membrane trafficking." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC195.
From brain to bones, stiffness and composition of the extracellular matrix vary greatly and play a role in cell responses. Substrate rigidity also impacts plasma membrane tension, which has a close relationship with membrane trafficking. How substrate rigidity and chemistry sensing may regulate exocytosis, which in turn regulates membrane tension, is still largely unknown. Here, I used pHluorin imaging of single vesicle exocytosis in cells cultured on substrates of controlled rigidity and composition to explore the regulation of VAMP2 and VAMP7-mediated exocytosis. I developed a computer software to automatically identify fusion events thus allowing quick analysis of batch data. I contributed to the study showing that VAMP7 exocytosis is regulated by src kinase which phosphorylates VAMP7 in its Longin domain (LD) (Burgo et al. JBC 2013). I further found that VAMP7 but not VAMP7 lacking LD- or VAMP2-mediated secretion was stimulated by substrate stiffness on laminin. VAMP7 and VAMP7 lacking LD were similarly sensitive to osmotic chock-induced membrane tension changes. Finally, i showed that LRRK1, a regulator of egf receptor transport, is a partner of the LD, and controls the retrograde transport of VAMP7. These approaches allowed me to reveal a new mechanism whereby substrate rigidity, by acting on integrin signalling, enhances VAMP7 exocytosis via LRRK1- and Rab21-dependent regulation of its peripheral readily-releasable pool (Wang et al. submitted). This mechanism may have broad potential relevance for plasma membrane dynamics in normal conditions and diseases, particularly cancer
Medkour, Terkia. "Modélisation mathématique et simulation numérique de la polymérisation de l’hémoglobine drépanocytaire." Thesis, Paris Est, 2008. http://www.theses.fr/2008PEST0044/document.
Sickle cell disease pathology exhibits a strong interindividual variability, which depends upon multiple, dynamic and interacting factors, from the molecular to the patient level. Sickle hemoglobin, hemoglobin S (HbS, a2bS 2 tetramer), is a mutant of HbA (a2b2), with a surface valine (hydrophobic) substituting a native glutamic acid (negatively charged). Such a mutation endows deoxygenated HbS with the propensity to agregate into polymers, altering erythrocyte properties –including its rheology and its interactions with vascular and circulatory cells. Thus HbS polymerization is a key etiological factor of sickle cell disease, if not the primum movens. Indeed, one therapeutical hypothesis (supported by observation) postulates that the reduction of intra-erythrocytic HbS fibers could improve patients clinical status by lowering the frequency and the severity of vasooclusive crisis. In order to better understand and manage sickle cell disease variability, it is essential to have a realistic description of HbS polymerization. This work aims at developing and validating a mathematical model of deoxygenated HbS polymerization, as a kinetic and thermodynamic process under the influence of concentration and temperature –the two most important modulators. Building on an existing, but linearized and uncomplete (Ferrone et al., 1985) model, we have implemented, corrected and updated, and quantitatively evaluated its dynamical performances: this was done by full numerical integration using Simulink©. This allowed us to make several improvements, related in particular to : (i) the heterogeneous nucleation pathway (seeding and formation of new fibers from pre-existing ones), (ii) the non-ideality of the HbS protein solution, caused by polymer fibers excluded volume (activity coefficients were calculated with the CPT, Convex Particle Theory), and (iii) the spatial organization of polymers into domains. The model developped in this work will ground the description of the dynamic influence (i) oxygenation and non-polymerizing hemoglobins, (ii) HbS polymers interactions with membrane and consequences upon rheological properties of sickle cell erythrocyte
Bernales, chavez Braulio. "Modélisation de l'hydrodynamique et des transferts dans les procédés de filtration membranaire." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4779/document.
Concentration polarization of solute at the membrane surface, because of osmotic pressure effects, is an important phenomenon that can cause substantial reductions in permeation. To understand these phenomena: we first analyze the filtration process for a pure solvent, imposing the influence of the driving pressure on permeation at the membrane. We obtain accurate analytical solutions for the flow fields. We then derive an analytical solution that coupled hydrodynamics to mass transfer for filtration systems working in a situation of High Pressure and Low Recovery. Second, we develop a numerical model that incorporates both physical aspects: the dependency of pressure on permeation and the influence of concentration polarization and their related osmotic effects in the effective pressure at the membrane. For that, the numerical approach solves the solute conservation equation coupled with the Navier-Stokes equations under the steady Prandtl approximation. The solution of the system is performed using a finite difference method of order 2. The validity of this approach is successfully demonstrated with the previous analytical solutions for hydrodynamics, as well as for the coupling with mass transfer. We then test the influence of the main operating parameters (inlet concentration, axial flow rate, operating pressure and membrane permeability) on the performance of the filtration system and compare the results with other numerical models that takes into account concentration polarization phenomenon. Finally, the validity of this model is quantitatively well-proved when using the reported data resulting from reverse osmosis experiments
Tran, Thanh Thuy. "Lattice model for amyloid peptides : OPEP force field parametrization and applications to the nucleus size of Alzheimer's peptides." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC187/document.
The neurodegenerative Alzheimer's disease (AD) is affecting more than 40 million people worldwide and is linked to the aggregation of the amyloid-β proteins of 40/42 amino acids. Despite many experimental and theoretical studies, the mechanism by which amyloid fibrils form and the 3D structures of the early toxic species in aqueous solution remain to be determined. In this thesis, I studied the structures of the eraly formed oligomers of the amyloid-β peptide and the critical nucleus size of two amyloid-β peptide fragments using either coarse-grained or all-atom simulations. First, at the coarse-grained level, I developed a lattice model for amyloid protein, which allows us to study the nucleus sizes of two experimentally well-characterized peptide fragments (Aβ)16-22 and (Aβ)37-42 of the Alzheimer's peptide (Aβ)1-42. After presenting a comprehensive OPEP force-field parameterization using an on-lattice protein model with Monte Carlo simulations and atomistic simulations, I determined the nucleus sizes of the two fragments. My results show that the nucleation number is 10 chains for (Aβ)16-22 and larger than 20 chains for (Aβ)37-42. This knowledge is important to help design more effective drugs against AD. Second, I investigated the structures of the dimer (Aβ)1-40 using extensive atomistic REMD simulations. This study provides insights into the equilibrium structure of the (Aβ)1-40 dimer in aqueous solution, opening a new avenue for a comprehensive understanding of the impact of pathogenic and protective mutations in early-stage Alzheimer’s disease on a molecular level
Ruiz, Echartea Maria Elisa. "Pairwise and Multi-Component Protein-Protein Docking Using Exhaustive Branch-and-Bound Tri-Dimensional Rotational Searches." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0306.
Determination of tri-dimensional (3D) structures of protein complexes is crucial to increase research advances on biological processes that help, for instance, to understand the development of diseases and their possible prevention or treatment. The difficulties and high costs of experimental methods to determine protein 3D structures and the importance of protein complexes for research have encouraged the use of computer science for developing tools to help filling this gap, such as protein docking algorithms. The protein docking problem has been studied for over 40 years. However, developing accurate and efficient protein docking algorithms remains a challenging problem due to the size of the search space, the approximate nature of the scoring functions used, and often the inherent flexibility of the protein structures to be docked. This thesis presents an algorithm to rigidly dock proteins using a series of exhaustive 3D branch-and-bound rotational searches in which non-clashing orientations are scored using ATTRACT. The rotational space is represented as a quaternion “π-ball”, which is systematically sub-divided in a “branch-and-bound” manner, allowing efficient pruning of rotations that will give steric clashes. The contribution of this thesis can be described in three main parts as follows. 1) The algorithm called EROS-DOCK to assemble two proteins. It was tested on 173 Docking Benchmark complexes. According to the CAPRI quality criteria, EROS-DOCK typically gives more acceptable or medium quality solutions than ATTRACT and ZDOCK. 2)The extension of the EROS-DOCK algorithm to allow the use of atom-atom or residue-residue distance restraints. The results show that using even just one residue-residue restraint in each interaction interface is sufficient to increase the number of cases with acceptable solutions within the top-10 from 51 to 121 out of 173 pairwise docking cases. Hence, EROS-DOCK offers a new improved search strategy to incorporate experimental data, of which a proof-of-principle using data-driven computational restraints is demonstrated in this thesis, and this might be especially important for multi-body complexes. 3)The extension of the algorithm to dock trimeric complexes. Here, the proposed method is based on the premise that all of the interfaces in a multi-body docking solution should be similar to at least one interface in each of the lists of pairwise docking solutions. The algorithm was tested on a home-made benchmark of 11 three-body cases. Seven complexes obtained at least one acceptable quality solution in the top-50. In future, the EROS-DOCK algorithm can evolve by integrating improved scoring functions and other types of restraints. Moreover, it can be used as a component in elaborate workflows to efficiently solve complex problems of multi-protein assemblies
Jobic, Yann. "Numerical approach by kinetic methods of transport phenomena in heterogeneous media." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4723/document.
A novel kinetic scheme satisfying an entropy condition is developed, tested and implemented for the simulation of practical problems. The construction of this new entropic scheme is presented. A classical hyperbolic system is approximated by a discrete velocity vector kinetic scheme (with the simplified BGK collisional operator), but applied to an inviscid compressible gas dynamics system with a small Mach number parameter, according to the approach of Carfora and Natalini (2008). The numerical viscosity is controlled, and tends to the physical viscosity of the Navier-Stokes system. The proposed numerical scheme is analyzed and formulated as an explicit finite volume flux vector splitting (FVS) scheme that is very easy to implement. It is close in spirit to Lattice Boltzmann schemes, but it has the advantage to satisfy a discrete entropy inequality under a CFL condition and a subcharacteristic stability condition involving a cell Reynolds number. The new scheme is proved to be second-order accurate in space. We show the efficiency of the method in terms of accuracy and robustness on a variety of classical benchmark tests. Some physical problems have been studied in order to show the usefulness of both schemes. The LB code was successfully used to determine the longitudinal dispersion of metallic foams, with the use of a novel indicator. The entropic code was used to determine the permeability tensor of various porous media, from the Fontainebleau sandstone (low porosity) to a redwood tree sample (high porosity). These results are pretty accurate. Finally, the entropic framework is applied to the advection-diffusion equation as a passive scalar
Babajee, Jayson. "Detailed numerical characterization of the separation-induced transition, including bursting, in a low-pressure turbine environment." Phd thesis, Ecole Centrale de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00984351.
Peng, Shuiran. "Analyse mathématique et numérique de plusieurs problèmes non linéaires." Thesis, Poitiers, 2018. http://www.theses.fr/2018POIT2306/document.
This thesis is devoted to the theoretical and numerical study of several nonlinear partial differential equations, which occur in the mathematical modeling of phase separation and micro-electromechanical system (MEMS). In the first part, we study higher-order phase separation models for which we obtain well-posedness and dissipativity results, together with the existence of global attractors and, in certain cases, numerical simulations. More precisely, we consider in this first part higher-order Allen-Cahn and Cahn-Hilliard equations with a regular potential and higher-order Allen-Cahn equation with a logarithmic potential. Moreover, we study higher-order anisotropic models and higher-order generalized Cahn-Hilliard equations, which have applications in biology, image processing, etc. We also consider the hyperbolic relaxation of higher-order anisotropic Cahn-Hilliard equations. In the second part, we develop semi-implicit and implicit semi-discrete, as well as fully discrete, schemes for solving the nonlinear partial differential equation, which describes both the elastic and electrostatic effects in an idealized MEMS capacitor. We analyze theoretically the stability of these schemes and the convergence under certain assumptions. Furthermore, several numerical simulations illustrate and support the theoretical results
Wong, King Jye. "Moisture absorption characteristics and effects on mechanical behaviour of carbon/epoxy composite : application to bonded patch repairs of composite structures." Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-00949293.