WorldCat Identities

École doctorale Sciences et Ingénierie, Matériaux, Modélisation et Environnement (Champs-sur-Marne, Seine-et-Marne)

Overview
Works: 51 works in 51 publications in 1 language and 78 library holdings
Roles: 996, Degree grantor
Publication Timeline
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Most widely held works by Matériaux, Modélisation et Environnement (Champs-sur-Marne, Seine-et-Marne) École doctorale Sciences et Ingénierie
Influence de la matière organique dissoute sur la spéciation et la biodisponibilité des métaux : cas de la Seine, un milieu sous forte pression urbaine by Benoît Pernet-Coudrier( )

1 edition published in 2008 in French and held by 4 WorldCat member libraries worldwide

This thesis was carried out on the framework of the ANR BIOMET research project (JC05_59809). The main objectives were to improve the current knowledge on the influence of dissolved organic matter (DOM) on metal speciation and bioavailability in urban aquatic system. The understanding of the influence of DOM on trace metal speciation and bioavailability required that the chemical composition of DOM, more exactly its binding sites should be well understood. Therefore, one part of this research focused on the isolation and characterization of DOM. The characterization of DOM, with a multidimensional approach was realized with a lot of various techniques (such as elemental, isotopic, functional and molecular) that were of prime importance to better understand the influence of DOM on trace metal speciation and bioavailability. To accomplish these objectives, the techniques such as potentiometry with ionic selective electrode and the recent electroanalytical technique AGNES and bioassays such as a bioaccumulation test (Fontinalis antipyretica) and an acute toxicity test (Daphnia magna) were performed in order to: - study the copper and lead binding by isolated DOM fractions in order to give some binding parameters of hydrophilic DOM and to better predict the fate of the trace metal. - evaluate the protective role of urban DOM on copper bioavailability. Results showed some particular characteristics of DOM from wastewater effluent such as a high proportion of hydrophilic DOM, i.e. a low hydrophobicity and a low degree of aromaticity underlying the low refractory character of urban DOM. Nevertheless a higher content of various functional groups was determined in urban DOM than in natural DOM. A very high content of proteinaceous structures was particularly identified in urban DOM. Binding experiments revealed for the first time on urban hydrophilic DOM, a higher content of binding sites than in natural DOM and these sites are strongly correlated to amino groups. The values of binding constant seem to not vary according to the nature of the fraction or the origin. The different approaches used to evaluate copper bioavailability depicted a protective role of DOM to the organisms Daphnia magna and Fontinalis antipyretica. Nevertheless this protective effect is hardly explained by the free ion concentration due to a bioavailability of some organic complexes. This feature could be explain with the high content of proteinaceous structures in these DOM fractions, since proteins are well know to play an important role in the transport mechanisms of trace metals into the organisms. Moreover, the DGT device (diffusive gradient in thin films) shows a good efficiency to assess the bioavailable copper
Les analogues archéologiques ferreux pour la compréhension des mécanismes de corrosion multiséculaire en milieu anoxique by Mandana Saheb-Djahromi( )

1 edition published in 2009 in French and held by 2 WorldCat member libraries worldwide

La compréhension des mécanismes de corrosion du fer à très long terme en milieu anoxique intéresse le domaine du stockage des déchets radioactifs à haute activité. En France, il est prévu de mettre en place un dispositif de stockage comprenant une matrice vitreuse enveloppée dans un conteneur en acier inoxydable, lui-même dans un surconteneur en acier doux en formation géologique profonde. Le dispositif devrait être imperméable dans cet environnement anoxique pendant plusieurs millénaires. Afin de prévoir les mécanismes d'altération des matériaux ferreux à très long terme, un axe de recherche s'est développé autour de l'étude d'analogues archéologiques de corrosion. Dans cette étude, les mécanismes de corrosion sont appréhendés à partir d'un corpus de clous âgés de 400 ans provenant du site de Glinet, choisi comme site de référence. Le premier axe de ce travail a consisté à caractériser finement le système de corrosion métal / produits de corrosion / milieu, en combinant des techniques multiéchelles. Les premiers résultats montrent que les échantillons ont été corrodés en milieu anoxique dans de l'eau riche en carbonate. De plus, le couplage de la microdiffraction des rayons X, de la microspectroscopie Raman et de la spectroscopie dispersive en énergie a mis en évidence trois types de faciès composés de carbonate de fer, sidérite et chukanovite, et de magnétite. Selon l'agencement de ces phases, la résistance électronique des produits de corrosion varie d'un pôle isolant à un pôle très conducteur. Dans le second axe de cette étude, des expériences de remise en corrosion en milieu synthétique représentatif du milieu d'enfouissement ont été menées. Dans un premier temps, des mesures de chronoampérométrie ont montré que la réaction de réduction de l'eau à la surface du métal est négligeable. Par ailleurs, un marquage de la réaction au cuivre et au deutérium a permis d'identifier respectivement les sites de consommation des électrons localisées en zone externe de la couche et les sites de précipitation des phases néoformées en zone interne proche de l'interface méta l/ produits de corrosion. L'ensemble de ces résultats a conduit à proposer des mécanismes de corrosion du fer à très long terme en milieu anoxique. L'un s'appuie sur la présence d'une couche non poreuse nanométrique formée à l'interface méta l/ produits de corrosion. L'autre suppose la formation d'un gel sur quelques micromètres de la zone interne de la couche de produits de corrosion. Cette étude sur les analogues archéologiques a permis de proposer des données concernant les mécanismes de corrosion des alliages ferreux à très long terme. Celles-ci devront être intégrées dans les modélisations du comportement des matériaux ferreux enfouis
Spectroscopie ultraviolet-visible et infrarouge de molécules clés atmosphériques by Aline Gratien( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Optical measurements of atmospheric minor constituents are carried using spectrometers working in different spectral ranges by ground, air or satellite instruments. However, the analysis and interpretation of the corresponding atmospheric spectra require good knowledge of the spectroscopic parameters. Moreover, spectroscopic measurements in laboratory are generally performed in a spectral region (IR or UV) and little of laboratory study has ever verified the consistency between the cross-sections in UV and IR. It is then difficult to compare atmospheric profiles measured in different regions. Consequently, the aim of the study was to intercalibrate spectra in the infrared and ultraviolet regions, by determining and/or checking the coherence of the cross section published in the literature. The experiments were performed at LISA by acquiring simultaneously UV and IR spectra at room temperature and atmospheric pressure using a common optical cell. This work relates to three atmospheric key species : formaldehyde (and its isotopes), ozone and nitrous acid. These compounds play a fundamental role in atmospheric physico-chemistry since they constitute the sources of the principal oxidant of the atmosphere: the hydroxyl radical. This laboratory work enables to have precise and coherent spectra of ozone, formaldehyde and nitrous acid in the mid-infrared and UV-visible regions in order to improve the precision of their measurements
L'habitat insalubre dans le Grand Agadir (Maroc) by Mohamed Atik( )

1 edition published in 2009 in French and held by 2 WorldCat member libraries worldwide

This research analyzes the problems of slums in its social aspect, and Urban Policy. Initially, we tried to find out how slums and illegal housing were developed in parallel with the reconstruction of the recent urban space. In a second step, we studied the internal structure of slums and illegal in terms of urban, social and economic, as well as relations with the rest of the city to measure their urbanity and integration thereof. At the end of this work, we analyzed the policy of RHI in its strategies and its defects, but also relations between the inhabitants and public authorities. The value of squatter settlements in Grater Agadir is original because it is an entirely new city was rebuilt on a modern strategy ansd proactive after the earthquake of 1960. The particular evolution of the urban area of this town in recent decades has resulted in rapid development of all its centers registering growth rates the highest in Morocco. This exceptional growth has created many problems in urban development with more concern are the proliferation of slums and illegal housing. Currently, nearly one in five households Greater Agadir still lives in these two types of habitat. According to the GPHC, 10,331 huts have been counted, which represents approximately 18,3% of urban population and 27 illegal neighborhoods with a total area of 2539 hectares on which 36 966 residents households, or appoximately 184 000 inhabitants. The evolution of these districts shows that there are people invested both financially and emotionally. Far from being places of temporary edge of town, these neighborhoods are rather non-integral parts of the city, as evidenced by their spatial organization and social exclusion of all basic amenities and urban integration (infrastructure, socio-economic facilities). The particularity of this phenomenom lies in the fact that it uses the same mateirals and same construction techniques, but it is characterized by the variety of social strata that live there and architectural typologies and urban planning. These slums have at least two common points which suffice to define them : first, they are "neighborhoods" of town, pieces of an area in which they operate and, secondly, they are down the urban hierarchy: less equipped, less affluent, less attractive. They combine the risks, exclusion, marginalization and extreme poverty. They also represnt a place of tension and resistance to any attempt at integration and regulation by government. They are also characterized by their dynamics, they are necessary because, as an active component of urban society. The slum population produces a number of goods and services consumed by the population of the formal city. These shantytowns are producing their own equipment and participate in the best of their ability to feed the coffers of the state and communities. Homeless, jobless, sociability, people are "speechless" without participation in the decision or absent social policies of resettlement. The "absorption" of slums has always been a political public claimed by the state that puts all its ressources to this form of housing disappears from the city. These people also want a decent home and a strategy for RHI, which takes into account their lifestyle, their social and economic
Atteignabilité hybride des systèmes dynamiques continus par analyse par intervalles : application à l'estimation ensembliste by Nacim Meslem( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Cette thèse porte sur le calcul d'une sur-approximation conservative pour les solutions d'équations différentielles ordinaires en présence d'incertitudes et sur son application à l'estimation et l'analyse de systèmes dynamiques à temps continu. L'avantage principal des méthodes et des algorithmes de calculs présentés dans cette thèse est qu'ils apportent une preuve numérique de résultats. Cette thèse est organisée en deux parties. La première partie est consacrée aux outils mathématiques et aux méthodes d'intégration numérique garantie des équations diff érentielles incertaines. Ces méthodes permettent de caractériser de manière garantie l'ensemble des trajectoires d'état engendrées par un système dynamique incertain dont les incertitudes sont naturellement représentées par des intervalles bornés. Dans cette optique, nous avons développé une méthode d'intégration hybride qui donne de meilleurs résultats que les méthodes d'intégration basées sur les modèles de Taylor intervalles. La seconde partie aborde les problèmes de l'identification et de l'observation dans un contexte à erreurs bornées ainsi que le problème d'atteignabilité continue pour la véri cation de propriétés des systèmes dynamiques hybrides
Étude expériementale et numérique de la dégradation de la mesure nucléaire d'aérosols radioactifs prélevés avec des filtres de surveillance by Tony Geryes( )

1 edition published in 2009 in French and held by 2 WorldCat member libraries worldwide

The measurement of radioactivity in the filters of airborne radioactive surveillance is a major difficulty metrology. Indeed, the absorption of a radiation in the filter media and the mass of aerosols accumulated distort the nuclear counters response. This thesis work focuses on the determination of correction factors for the radioactivity loss in the survey filters. In a first step, radioactive filters representing the atmospheric samples have been prepared using the nuclear test bench ICARE. The experimental study on reference filters provided a database to determine correction factors for various filtration conditions. The second step of the work proposed a new numerical method developed to determine the correction factors. It consists of coupling GeoDict for particles filtration simulations and MCNPX simulations for a transport in matter. The good agreement obtained by comparing the numerical and experimental correction factors has permitted to validate the numerical model
Perfectionnement d'un algorithme adaptatif d'optimisation par essaim particulaire : application en génie médical et en électronique by Yann Cooren( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Metaheuristics are a new family of stochastic algorithms which aim at solving difficult optimization problems. Used to solve various applicative problems, these methods have the advantage to be generally efficient on a large amount of problems. Among the metaheuristics, Particle Swarm Optimization (PSO) is a new class of algorithms proposed to solve continuous optimization problems. PSO algorithms are inspired from the social behavior of animals living in swarm, such as bird flocks or fish schools. The particles of the swarm use a direct way of communication in order to build a solution to the considered problem, based on their collective experience. Known for their e ciency, metaheuristics show the drawback of comprising too many parameters to be tuned. Such a drawback may rebu some users. Indeed, according to the values given to the parameters of the algorithm, its performance uctuates. So, it is important, for each problem, to nd the parameter set which gives the best performance of the algorithm. However, such a problem is complex and time consuming, especially for novice users. To avoid the user to tune the parameters, numerous researches have been done to propose adaptive algorithms. For such algorithms, the values of the parameters are changed according to the results previously found during the optimization process. TRIBES is an adaptive mono-objective parameter-free PSO algorithm, which was proposed by Maurice Clerc. TRIBES acts as a black box , for which the user has only the problem and the stopping criterion to de ne. The rst objective of this PhD is to make a global study of the behavior of TRIBES under several conditions, in order to determine the strengths and drawbacks of this adaptive algorithm. In order to improve TRIBES, two new strategies are added. First, a regular initialization process is defined in order to insure an exploration as wide as possible of the search space, since the beginning of the optimization process. A new strategy of displacement, based on an hybridation with an estimation of distribution algorithm, is also introduced to maintain the diversity in the swarm all along the process. The increasing need for multiobjective methods leads the researchers to adapt their methods to the multiobjective case. The di culty of such an operation is that, in most cases, the objectives are con icting. We designed MO-TRIBES, which is a multiobjective version of TRIBES. Finally, our algorithms are applied to thresholding segmentation of medical images and to the design of electronic components
Synthèse, caractérisation et étude des propriétés thermodynamiques d'hydrogénation de nanocomposites matériaux poreux / métaux-alliages by Renato Campesi( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Nowadays many technological and scientific constraints have limited the finding of a suitable system and/or material able to reversibly store hydrogen at room temperature and ambient pressure for automotive application. An interesting way to overcome such limits could be the synthesis of hybrid materials (porous materials/metals or alloys composites) for which the adsorption and absorption processes can be combined in order to get higher hydrogen storage capacity. In this work, several porous materials displaying a well defined nanometric pore structure have been investigated. Among them a carbon template (CT) and a metal organic framework (MOF-5) have been chosen. In addition, several noble metals (Ni, Pd and Pt) have been used due to their ability to dissociate hydrogen and to form alloys. Two synthesis routes have been followed in order to synthesize hybrid composites: metal salts infiltration and mechanical grinding. In particular, the investigation of the structural, textural and hydrogen storage properties of the CT/metal composites has proven that a synergic mechanism between the CT pores and the metallic nanoparticles takes place during the hydrogen ad/absorption process. This interaction leads to an enhancement of the hydrogen storage capacity of each hybrid component taken separately
Mobilité des éléments traces métalliques dans les sédiments : couplage et comparaison des approches chimique et microbiologique by Catherine Gounou( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Antropic activities lead to the metallic contamination of river sediments. Most of trace metals are sorbed on sediments but a part of them can be released into aquatic environment when environmental conditions are modified. This is often due by the autochthonous microbial activity. Microbial activites and their consequences on the mobility of metals have been widely studied in soils. Metals are released through direct or indirect microbial mechanisms. Such studies in the case of sediments are very seldom. However, it can be usefull to understand the microbial mechanisms of metal release in sediments, and particularly for a good management of dredged sediments. In this environmental framework, the aim of this research work was to understand and to evaluate the role of the microbial and chemical mechanisms in the release of metals from river sediments in anaerobic conditions. Firstly, sediments from the Marne and Seine rivers were incubated in anaerobic conditions. A high solubilisation of iron and manganese occurred associated to the solubilisation of trace metals (Co, Cu, Ni, Pb). Meanwhile, organic acids were produced and the medium was acidified. Thus fermentation was supposed to be the main process of microbial metabolism. Furthermore these observations led us to suppose the presence of iron-reducing bacteria. In a second step, the extent of the iron-reducing activity was studied. The main iron-reducing bacteria identified in the Marne sediments belonged to the species Clostridium butyricum and Paenibacillus polymyxa. The use of a geochemical model revealed that fermentation and reduction of iron(III) were the main metabolic pathways. Finally direct (enzymatic reduction) and indirect (complexation with organic acids, acidification) impacts of iron-reducing bacteria on the release of metals were compared. Acidification and organic acids had a weak impact on metal solubility in the range of studied pH (between 6,5 and 5). Enzymatic reduction is the main mechanisms of metal release in anaerobic conditions. Indeed the metallic concentrations can be 40 times higher in the presence of iron-reducing bacteria
Étude expérimentale du transport des aérosols dans un espace clos ventilé et impact des principales stratégies d'épuration microbiologique de l'air sur l'exposition des occupants by Stéphane Delaby( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Exposure to bioaerosols in indoor environments is associated with a wide range of adverse effects on health including infectious diseases, acute toxic effects and allergies. In order to guard against this phenomenon, the ventilation and air treatment industry has developed and marketed many air control strategies. However, at present, there is no methodology adapted to the evaluation of the relevance of these strategies. The aim of this research work was to characterize, in a first time, the progress of microbiological aerosol from the original source, to their eventual inhalation by person exposed, considering their dissemination through the indoor environments. Secondly, the work consisted of determining the efficiency of air cleaner devices applied to control indoor air quality. For this point, a global approach of evaluation in 3 steps was adopted, consisting of studying the efficiency of the epuration principle implemented, determining the intrinsic performance of the systems in dynamic conditions and their impact on the exposure level of the exposed persons. The tests carried out with air cleaner devices (filtration and photocatalysis) have shown that the intrinsic performance wasn't able to estimate the beneficial impact of these systems on the exposure level of people when there were applied in indoor environments. So the intrinsic performance of devices is not the single impact factor, the airflow promoted by the device is also a factor to consider. Moreover, the characterization of indoor airflows and airborne particles transport is essential to define a coherent strategy of air treatment
Estimation des déformations myocardiques par analyse d'images by Yasmina Chenoune( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

The work presented in this thesis is related to the cardiac images processing and the cardiac contractile function study, for a better comprehension of cardiac physiopathology and diagnosis. We implemented a method for the segmentation of the endocardial walls on standard MRI without tags. We used an approach based on the level set method, with a region-based formulation which gives satisfactory results on healthy and pathological cases. We proposed a practical method for the quantification of the segmental deformations in order to characterize the myocardial contractility. The method was clinically validated by the assesment of doctors and by comparison with the HARP method on tagget MRI. To improve the measurements precision, we proposed an iconic MRI/CT multimodal registration algorithm, using the maximization of the mutual information. We applied it to the localization of short-axis slices in CT volumes with good results. This work has as prospect its application to obtain high spatial and temporal resolutions CT sequences
Contribution ? la mod?lisation m?canique du comportement dynamique, hyper?lastique et anisotrope de la paroi art?rielle by Ingrid Masson( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Cardiovascular diseases are the number one cause of death globally and they are currently the subject of many researches. In studies of arteries, one of the aims is to improve understanding in biological mechanisms involved in diseases such as hypertension, atherosclerosis or aneurysm. The mechanical studies that were carried out predominantly rely on in vitro experimental testing, which limit their interest and application in clinical diagnosis. In this work, a theoretical modelling of the 3D carotid artery mechanical behaviour is proposed by assuming a hyperelastic, anisotropic, active, pre-stretched and dynamic wall structure. The experimental measurements were obtained in vivo from rat and human common carotid arteries, with non invasive recordings in the human case. The mechanical boundary value problem is solved semi-analytically over a cardiac cycle by also assuming the surrounding perivascular tissue. The best-fit values of the model parameters are estimated by nonlinear least-squares method, in particular those describing the mechanical characteristics of wall microconstituents (elastin, collagen, smooth muscle). The proposed modelling is able (i) to reconstruct the in vivo dynamic measured intraluminal pressures and (ii) to compute the wall stress fields which seem to be consistent with the arterial physiology. A correlation between patient age and the parameters related to residual stresses and collagen fibres shows the relevance of the theoretical modelling and the originality of the approach which, thereby, would be able to be used in studies of arterial pathological cases
Étude de l'organisation à l'état solide et de la dynamique des chaines polymères dans les nanocomposites polyéthylène/POSS by Domitille Pitard( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Liées de façon covalente à des chaînes polymères, les nanoparticules POSS (polysilses-quioxanes polyédriques) permettent l'obtention de matériaux nanocomposites hybrides orga-nique/inorganique. Ces nanoparticules présentent deux intérêts majeurs: des dimensions bien définies (cœur inorganique: 0.5 nm), ainsi que leur caractère hybride ( groupements organiques entourant les cages inorganiques). Les nanocomposites polymère/POSS peuvent présenter un renfort important des propriétés mécaniques et de la stabilité thermique de la matrice polymère. Cependant, l'origine moléculaire de ce renfort reste mal comprise. Aussi, afin de mieux comprendre le renfort des propriétés mécaniques de la matrice, nous avons étudié l'effet des particules POSS sur l'organisation à l'état solide et la dynamique des chaînes po-lymères au sein d'une matrice semi-cristalline. Pour cela, nous avons considéré une série de copolymères polyéthylène-POSS, caractérisés par une large gamme de concentration en POSS. Le polyéthylène et le POSS ayant intrinsèquement tendance à cristalliser, les copolymères présentent des organisations à l'état solide complexes que nous avons caractérisés par l'utilisation combinée de la calorimétrie différentielle à balayage (DSC), de la diffraction des rayons X aux grands angles (DRX) et de la résonance magnétique nucléaire en phase solide (RMN). Dans un second volet de cette étude, nous nous sommes intéressés à la dynamique des chaînes de polyéthylène en phase amorphe et à l'évolution de celle-ci avec le taux de charge des nanocomposites. Enfin, nous avons également étudié, de façon sélective, la dynamique des segments de chaînes de polyéthylène situés au voisinage de la charge
Adaptation aux métaux lourds d'une Fabacée (légumineuse) : réponses phonologique et moléculaire au plomb du Lathyrus sativus L. by Judicaëlle Brunet( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

La gesse commune (Lathyrus sativus L.) est une légumineuse cultivée principalement en Inde, au Bangladesh et en Ethiopie qui présente des niveaux de résistance élevés pour de nombreuses contraintes abiotiques, telles que la sécheresse et l'inondation. Dans ce travail, les capacités de tolérance du Lathyrus (lignées locales "Raipur" et "Bangladesh") à une autre contrainte abiotique, la présence de plomb, ont été déterminées des points de vue physiologique et moléculaire. Un système expérimental de culture hydroponique a été mis au point pour ces plantes. Le plomb y est introduit sous forme de nitrate de plomb (Pb(NO3)2). Les teneurs en plomb des différents organes des plantes (racines, tiges, feuilles) ont été déterminées par ICP-OES. Les réponses cellulaires dans ces organes ont été étudiées par RTPCR quantitative (PCR en temps réel). Des amorces spécifiques du Lathyrus ont été dessinées à partir des 11 séquences d'ADN complémentaires (ADNc) isolées pour la première fois et séquencées. L'un des ADNc isolé est complet et code une cystéine protéase (LsCP, 427 aa). Les autres sont des ADNc partiels et correspondent à une aspartique protéase (LsAP, 270 aa), deux ascorbate peroxidases cytosolique (LsAPXc, 195 aa) et peroxisomale (LsAPXp, 226 aa), une protéine de choc thermique ("Heat Shock Protein 70" ; LsHSP70, 287), une homoglutathion synthétase (LshGSHS, 329 aa), une glutathion S-transférase (LsGST, 66 aa), une glutathion réductase (LsGR, 336 aa), une phytochélatine synthétase (LsPCS, 64 aa), une phospholipase D a (LsPLDa, 288 aa), un transporteur membranaire spécifique du Pb (LsCNGC, 136) et une protéine soluble (LsABCt, 331 aa). Les plantes exposées au nitrate de plomb accumulent de grandes quantités de métal dans leurs racines sous forme de plomb fortement lié aux tissus. L'accumulation d'ARN messagers de la LsPLDa suggère que les racines subissent une contrainte cellulaire et s'y adaptent. La stimulation de l'expression des gènes LsGST, LsGR et LsAPX correspondrait à la formation de complexes Pb-glutathion et à une activation du cycle ascorbate-glutathion pour la neutralisation des espaces activées de l'oxygène (ROS) délétères. Dans les feuilles exemptes de plomb, l'augmentation de l'expression des gènes LsCP, LsAP, LsAPXc, LsAPXp, LsHSP70, LsGR et LsPCS semble indiquer l'émission d'un signal racinaire transmis de manière systémique vers le reste de la plante où il déclenche la sur-expression de ces gènes. Ceci pourrait permettre aux tissus épargnés par le polluant de se préparer à son éventuelle arrivée. La chélation du Pb avec de l'EDTA dans le milieu de culture conduit à son transport vers les parties aériennes et à son accumulation dans les feuilles. L'expression du gène LsCNGC chez ces plantes est activée dans les feuilles, suggérant une participation de ce transporteur à l'entrée des complexes Pb-EDTA dans le symplasme. Comme observé chez d'autres espèces végétales, le plomb affecte le métabolisme du glutathion chez la gesse commune. Cependant, la mise en évidence d'une réaction systémique en réponse au plomb à partir des racines ainsi que la surexpression de gènes d'autolyse sont réalisées pour la première fois et pourraient être des éléments contribuant fortement à la tolérance au plomb chez cette espace végétale sous-utilisée
Exploitation de la statistique du champ de speckle pour l'aide au diagnostic du syndrome cutané d'irradiation aigüe : confrontation des résultats biophysiques et biologiques by Odile Carvalho( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

Overexposure to ionizing radiation is now a growing concern of clinicians. In case of external exposure, the skin is the first tissue exposed. However, there are no tools that can diagnose pathological tissue. The objective of this work is to demonstrate the possibility of using a non-invasive method for in vivo diagnosis and prognosis of acute cutaneous radiation syndrome. The first part of this work concerns the choice of the investigation method. Interaction of coherent light and scattering medium creates a phenomenon called speckle. A classical frequential analysis on the spekle field is supplemented by a stochastic approach to extract parameters characterizing speckle patterns. In the second part, the experimental setup has been tested in order to understand the parameters behavior in function of some physical properties of synthetic scattering media. The study revealed that some of the speckle parameters were more influenced by big scatterers (Mie) while others were by the smallest (Rayleigh). The third part concerns the in vivo application of this method on acute cutaneous radiation syndrome in pigs. Analysis of the results gained during the monitoring of several animals showeb the ability to discriminate between irradiated and healthy zones several weeks before apparition of firsts clinical signs. Finally, in order to understand the results on the radiological burn, we have confronted all physical results and those obtained by histological analyses
Quelques notions d'irrégularité uniforme et ponctuelle : le point de vue ondelettes by Marianne Clausel( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

The main purpose of this thesis is the definition and the study of different concepts of uniform or pointwise irregularity which enable one to account for the fact that a function may have 'large increments' at any scales. To this end, we 'invert' the usual notions of Hölderian regularity. The main goal is then to relate these different concepts to wavelet theory. The wavelet criteria supplied enable to define functions or random fields the behavior of which differ with respect the family of scales chosen. Moreover, if we consider the pointwise point of view, a natural question is that of the definition of a weak multifractal analysis related to pointwise irregularity. Finally, we study examples of random fields with some properties of directional regularity. Thus we focus on the study of a special model of operator scaling Gaussian field. We then extend this model and introduced group self-similar Gaussian fields
Étude mathématique d'écoulements de fluides viscoélastiques dans des domaines singuliers by Zaynab Salloum( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

In this PHD thesis, we study three problems for viscoelastic flows of Oldroyd type. First, we study steady flows of slightly compressible in a bounded domain with non-zero velocities on the boundary ; the pressure and the extra-stress tensor are prescribed on the part of the boundary corresponding to entering velocity. This causes a weak singularity in the solution at the junction of incoming and outgoing flows. We also study the problem of steady flows of slightly compressible fluids with zero boundary conditions in a domain with an isolated corner point. Using a method of fixed point (first and second problems) and a Helmoltz decomposition (second problem), we show some results of existence and uniqueness of solutions. In the last part, we study the case of a non-steady flow : we show some results of local and of global existence, with sufficiently small initial data, for compressible flows. The zero-Mach number limit is also established
Activation de composés aromatiques et hétéroaromatiques pour la formation de liaisons C-C et C-N par catalyse au cobalt by Jeanne-Marie Begouin( )

1 edition published in 2009 in French and held by 2 WorldCat member libraries worldwide

Transition metal-catalyzed cross-coupling reactions allowing the formation of C-C or C-Heteroatom bonds underlie the synthesis of key intermediates for pharmaceutical, supramolecular chemistry and material sciences. Thereby, the development of these methodologies is prominent and an increasing number of studies are devoted to these processes. However, some metallic catalysts are known to be rather expensive or toxic. Consequently, the development of alternative sustainable catalysts such as cobalt or ironbased catalysts has been studied over the past few years. Cobalt-catalysts have been little-used although they have shown to be effective for various C-C bond forming reactions. Functionalized arylzinc reagents can be readily obtained from the corresponding arylhalides using a CoBr2-catalyzed reaction. First we envisioned using these arylzinc reagents in CoBr2-catalyzed cross-coupling reactions with chlorodiazines and chlorotriazines leading to aryldiazines and aryltriazines. Benzylzinc reagents had also been used in these reactions and we synthesized various benzyltriazines in this manner. We also studied whether we can use other kind of substrates in these reactions. Thus, we performed CoBr2-catalyzed cross-coupling reactions between arylzinc reagents and methylthiopyrimidines or methylthiobenzo[b]thiazole derivatives leading to 2,4-diarylpyrimidines and 2- arylbenzo[b]thiazole. Then, we studied the reactivity of benzonitrile derivatives in direct cross-coupling reactions with arylhalide based on C-CN bond activation using CoBr2 as catalyst. Finally, we also carried out the study of CoBr2-catalyzed C-N cross-coupling reactions for the synthesis of diarylamines
Élaboration par solidification dirigée et comportement mécanique de céramiques eutectiques à base d'oxydes réfractaires : rôle de la microstructure sur la fissuration et la déformation plastique à haute température by Loïc Perrière( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

In the general context of energy savings at a global scale, the improvement of the thermal efficiency of both terrestrial and aeronautical gas turbines will require to increase the turbine inlet gas temperature. The development of new materials, stable up to 1 500°C, is thus necessary. In this context, Directionally Solidified Eutectic Ceramics (DSEC), prepared from Al2O3 and Ln2O3-based systems, could be a potential solution. Their microstructure consists of two single-crystal phases continuously entangled in a threedimensional interpenetrating network without grain boundaries, pores or colonies. The outstanding stability of these microstructures gives rise to a high strength and creep resistance at high temperature. Our research consisted first in obtaining, by directional solidification, several eutectic systems, either binary or ternary (with addition of a toughening third ZrO2 phase). The six most promising DSEC (3 binary systems: Al2O3 - Y3Al5O12, Al2O3 - Er3Al5O12, Al2O3 - GdAlO3, and 3 ternary systems: Al2O3 - Y3Al5O12 - ZrO2, Al2O3 - Er3Al5O12 - ZrO2, Al2O3 - GdAlO3 - ZrO2) have then been selected to study some of their mechanical properties. Several crack propagation patterns have been detected after biaxial flexure testing, and partially explain the toughening which has been proven for DSEC. Attention has been paid to the possibility of crack deflection in the various phases and in the phase boundaries, a phenomenon which may markedly improve the toughness of these eutectic ceramics. These observations have been correlated to internal stress calculations and piezo-spectroscopic measurements. Finally, the study of the creep behavior showed that the deformation mechanisms evolve with the macroscopic solicitation (temperature and stress). microstructure. Moreover, post mortem TEM observations exhibited that creep mechanisms are strongly dependant on the entangled microstructure
?tude de la fragilisation des aciers T91 et 316L par l'eutectique plomb-bismuth liquide by Zehoua Hamouche( )

1 edition published in 2008 in French and held by 2 WorldCat member libraries worldwide

The aim of this work is to study liquid metal embrittlement (LME) on the T91/Pb-Bi and 316L/Pb-Bi systems. A particular attention is paid to obtain a better understanding of the mechanisms of fracture when steels are in contact with liquid metal. This work has been performed within the European projects MEGAPIE-TEST and EUROTRANS which aim to prove the feasibility of lead-bismuth nuclear systems such as spallation target and subcritical reactors. The effect of liquid Lead Bismuth Eutectic (LBE) on 316L and T91 steels has been studied in plane stress conditions as a function of temperature and strain rate, using a CCT geometry adapted for the study of crack propagation. The presence of LBE modifies the fracture mechanism of T91 and prevents fracture by growth and coalescence of cavities. Cracking proceeds by shear band decohesion. This embrittlement effect is very pronounced at low deformation rate whereas at the high strain rate range investigated, a brittle to ductile transition is observed. The temperature variation of the transition rules out LME mechanisms based on dissolution. A fracture mechanics analysis by the J-?a methodology allowed the quantification of the embrittlement degree which is estimated to 30% reduction in the energy required for crack propagation. The mechanical properties of the 316L steel are weakly affected by the presence of LBE, in spite of a change in the plastic deformation at the highest triaxiality point which strongly affecting fracture surfaces. The mechanism of this embrittlement seems to be based on the deformation localization at the crack tip combined with the phenomenon of surface energy reduction induced by the liquid metal adsorption. It does not involve any diffusion process. The deformation localization is confirmed by an electron microscopy study of the crack tip plasticity of 316L under the influence of a liquid metal
 
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École doctorale SIMME

Sciences et Ingénierie, Matériaux, Modélisation et Environnement

SIMME

Université Paris-Est (Champs-sur-Marne). École doctorale Sciences et Ingénierie, Matériaux, Modélisation et Environnement

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French (20)