La synthèse de glycomonomères à base d'oligoalginate (AlgiMERs) et leur polymérisations conventionnelles et RAFT en solution aqueuse ont été étudiés. Premièrement, l'oligoalginates de départ ont été transformés soit dans le glycosylamines correspondant ou en amino alditols (via une amination réductrice). A cette étape, l'optimisation des protocoles d'amination ont été identifiées par la réalisation d'une étude systématique sur un simple acide uronique (acide D-glucuronique). Deuxièmement, les sucres aminés ont été obtenus a réagi avec une électrophile portant un groupe vinyle polymérisable à céder AlgiMERs. Le glycomonomères résultant n'a pas homopolymérisé même en haute force ionique et pour temps de réaction longs, mais leur copolymérisations radicalaire conventionnelles avec N-(2-hydroxyéthyl)méthacrylamide (HEMAm) donne de glycopolymères avec de haute mass molaires (Mw ≈ 1.500.000 Da) contenant jusqu'à 50% en masse de oligoalginate. Une étude cinétique a confirmé que la consommation des deux monomères suivi une cinétique de premier ordre et que les AlgiMERs ont été intégrées tôt dans le processus de polymérisation. Basé sur ces résultats, l'enquête a été étendue à la copolymérisation radicalaire vivante en milieu aqueuse et glycopolymères gradient bien définies ont été obtenues (Mn = 12 000 Da - 90 000 Da; PDI ≤ 1,20). Enfin, j'ai pu prouver qu'un polymère synthétique portant des résidus d'oligo (1→4)-α-L-guluronan conduit des gels en présence d'ions Ca2+ et offre un hydrogel transparent et stable.

Many biological processes, pathogens, and pharmaceuticals act upon, cellular membranes. Accordingly, cell membrane mimics are attractive targets for biosensing, with research, pathology, and pharmacology applications. Lipid bilayers represent a versatile sensor functionalization platform providing antifouling properties, and many receptor integration options, uniquely including transmembrane proteins. Bilayer-coated sensors enable the kinetic characterization of membrane/analyte interactions. Addressed theoretically and experimentally is the self-assembly of model membranes on plasmonic sensors. Two categories of plasmonic sensors are studied in two parts. Part I aims to deposit raft-forming bilayers on planar nanoaperture arrays suitable for multiplexing and device integration. By vesicle fusion, planar bilayers are self-assembled on thiol-acid modified flame-annealed gold without the need for specific lipid head-group requirements. Identification of coexisting lipid phases is accomplished by AFM imaging and force spectroscopy mapping. These methods are successfully extended to metallic, plasmon-active nanohole arrays, nanoslit arrays and annular aperture arrays, with coexisting phases observed among the holes. Vis-NIR transmission spectra of the arrays are measured before and after deposition, indicating bilayer detection. Finally, the extraction of membrane proteins from cell cultures and incorporation into model supported bilayers is demonstrated. These natural membrane proteins potentially act as lipid-bound surface receptors. Part II aims to encapsulate in model lipid bilayers, metallic nanoparticles, which are used as probes in surface enhanced Raman spectroscopy. Three strategies of encapsulating particles, and incorporating Raman-active dyes are demonstrated, each using a different dye: malachite green, rhodamine-PE, and Tryptophan. Dye incorporation is verified by SERS and the bilayer is visualized and measured by TEM, with support from DLS and UV-Vis spectroscopy. In both parts, lipid-coated sensors are successfully fabricated and characterized. These results represent important and novel solutions to the functionalization of plasmonic surfaces with biologically relevant cell membrane mimics.

No description available.

Les inclusions rigides sont un concept récent développé dans le prolongement des fondations mixtes, avec un matelas de transfert de charges entre les colonnes et la structure. Des méthodes de calculs et des concepts de sécurité existent pour ces systèmes combinés, notamment en France où le module pressiométrique mesuré et les recommandations ASIRI (IREX 2012) pour les inclusions rigides sont utilisés. Le dimensionnement classique des pieux basé sur une simple vérification de la portance des colonnes isolées ne peut pas être appliqué à ces systèmes combinés. Les tassements peuvent être plus importants du fait de la part significative de charge reprise par le sol. Le présent travail est une contribution au développement des méthodes de calcul et de dimensionnement en déplacement (préconisé par l'Eurocode 7, EN 1997-1 2004) pour les systèmes combinés sous charge verticale, en particulier au niveau international où des mesures in situ de module de sol ne sont généralement pas disponibles. Les éventuelles particularités de ces systèmes, notamment la sensibilité de colonnes non renforcées de petit diamètre, devaient également être examinées. La méthode de transfert de charge (“load transfer method”, LTM) est identifiée comme un outil d'ingénieur particulièrement adapté au calcul des systèmes combinés présentant une géométrie relativement simple. L'interaction sol-colonne en frottement et en pointe est définie par des courbes de transfert de charge (ou courbes “t-z” et “q-z”). Les méthodes en milieu continu comme la méthode des éléments finis sont à réserver en général aux cas complexes. Le comportement non-linéaire des semelles est examiné sur la base de mesures obtenues dans la littérature. Cette étude aboutit à la proposition d'une courbe charge-tassement hyperbolique pour les semelles. Cette courbe de mobilisation est définie de sorte qu'il y ait concordance avec la méthode linéaire habituelle pour un tiers de la charge ultime de la semelle. Le comportement de pieux isolés est étudié avec de nombreux essais de chargement instrumentés et non-instrumentés pour différents types de pieux et de sol. Une alternative aux courbes de transfert de charge selon Frank et Zhao (1982), basées sur le module pressiométrique, est recherchée. Des courbes de transfert de charge de type racine cubique et hyperbolique sont proposées pour tous types de pieux et de sol. La raideur des courbes proposées dépend d'une bonne estimation des valeurs ultimes de frottement et de résistance de pointe. Au contraire, la raideur initiale des courbes de Frank et Zhao est entièrement définie par le module pressiométrique, ce qui permet d'éviter des erreurs en termes de raideur. Les courbes de mobilisation proposées pour les fondations superficielles et pour les pieux sont combinées et étendues au cas des systèmes combinés. Cette méthode est implémentée comme option LTM dans le programme KID (Keller company 2015). Les prévisions avec le modèle proposé sont en très bonne adéquation avec les mesures effectuées sur 3 sites documentés dans la littérature. Une étude paramétrique montre une transition continue entre la fondation mixte et les inclusions rigides et une possibilité d'optimisation avec une diminution significative des efforts dans les colonnes et dans la fondation superficielle si un matelas est utilisé. En complément, une comparaison avec des calculs en éléments finis en 3D dans un cas théorique de semelle sur colonnes confirme que la méthode de transfert de charge développée est très performante pour des géométries simples. Une analyse de sensibilité est effectuée avec des modèles éléments finis axisymmétriques et 3D avec Plaxis (2013, 2014). Les imperfections géométriques ont principalement une incidence sur l'intégrité structurelle des colonnes non-armées de faible diamètre. Cependant, ces effets sont atténués dans les systèmes combinés en comparaison avec la colonne isolée du fait des possibilités de redistribution des charges dans le système / Rigid inclusions represent a further development of combined pile-raft foundations, comprising a load transfer platform between the columns and the structure. Calculation methods and design concepts are available for such combined systems in particular in France, based on measured pressuremeter modulus values and on the French recommendations ASIRI for rigid inclusions (IREX 2012). The conventional pile design consisting only of a bearing capacity check for the individual column cannot be applied to such combined systems. The expected settlements may be larger due to a significant load proportion supported by the soil. The present work contributes to the development of displacement-based calculation methods (advocated by the Eurocode 7, EN 1997-1 2004) and design methods for combined systems under vertical loads, in particular on an international level where in general no in situ soil modulus values are measured. Possible particularities of such systems, like the sensitivity of unreinforced small-diameter columns, also had to be investigated. The load transfer method (LTM) is identified as a straightforward engineering tool for the calculation of combined systems with relatively simple geometries. The soil-column interaction in terms of skin friction and tip resistance is described by deformation-dependent load transfer curves (or “t-z” and “q-z” curves). Continuum methods like the finite element method should be preferred only for complex cases in general. The non-linear load-settlement behaviour of single footings up to failure is analysed based on measurements given in the literature. This yields the proposal of a hyperbolic load-settlement curve for footings. This mobilization curve is defined in a way to match the linear usual method for one third of the footing ultimate load. The behaviour of single piles is investigated based on numerous available instrumented and non-instrumented pile load tests with different pile and soil types. A reliable alternative to the load transfer curves after Frank and Zhao (1982), which are based on the pressuremeter modulus, is sought. Cubic root and hyperbolic axial load transfer curves are proposed for all pile and ground types. The stiffness accuracy of the proposed curves depends on an accurate estimation of the ultimate skin friction and tip resistance values. On the contrary, the initial stiffness of the Frank and Zhao curves is fully described by the pressuremeter modulus, avoiding thus errors in the stiffness. The proposed mobilization curves for the shallow and pile foundation behaviours are combined and extended for all combined systems. The proposed method is implemented as the LTM option into the software KID (Keller company 2015). The prediction with the developed model matches very well the measurements made for 3 different cases from the literature. A parametric study shows a smooth transition between the combined pile-raft foundation case and the rigid inclusion case and a potential for optimisation with a significant reduction of the internal forces in the columns and in the rigid slab when a load transfer platform is used. In addition, a comparison with 3D finite element calculations for a theoretical footing case with columns confirms that the developed load transfer method is very reliable for simple geometries. Sensitivity investigations using the axisymmetric and 3D finite element method with Plaxis (2013, 2014) are performed. Geometrical imperfections impact mainly the structural integrity of small-diameter unreinforced columns. However, these effects are reduced in combined systems compared to the single column case due to the possibility of redistribution of the loads within the system

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-01-16T17:25:01Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Tese - Rodrigo Alves Moreira - 2014.pdf: 6048324 bytes, checksum: 289d0c70e7ed1db107b03924d35a81de (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-01-16T17:37:28Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Tese - Rodrigo Alves Moreira - 2014.pdf: 6048324 bytes, checksum: 289d0c70e7ed1db107b03924d35a81de (MD5) / Made available in DSpace on 2015-01-16T17:37:28Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Tese - Rodrigo Alves Moreira - 2014.pdf: 6048324 bytes, checksum: 289d0c70e7ed1db107b03924d35a81de (MD5) Previous issue date: 2014-06-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Cutaneous leishmaniasis is a neglected tropical disease that infects millions of people worldwide, representing a serious public health problem. The miltefosine (MT) is an alkylphospholipid that has been approved for the treatment of breast cancer metastasis and visceral leishmaniasis, although the mechanism of action at the molecular level is poorly understood. Electron paramagnetic resonance (EPR) spectroscopy of the lipid spin lebel analog of stearic acid (5-DSA) and the maleimide derivative spin label (6-MSL) covalently bound to membrane proteins showed that the MT causes a large increase in the molecular dynamics of erythrocyte membranes (ghosts) and detergent resistant membranes (DRMs) prepared from erythrocyte membranes. In the vesicles of lipid raft constituents, it was shown that 20 mol% sphingomyelin could be replaced by 20 mol% MT with no change in the molecular dynamics. Furthermore, the effect of MT on DRMs was more pronounced than in erythrocyte ghosts, supporting the hypothesis that MT is a lipid raft modulator. At the reported MT-plasma concentrations found during the treatment of leishmaniasis (31-52μg/mL), our measurements in blood plasma indicated a hemolytic level of 2-5% and also showed that the MT concentration that changes the erythrocyte membrane fluidity to an extent that is detectable by EPR spectroscopy causes about 46% hemolysis. Subsequently, EPR studies performed with the same spin labels in the membrane of Leishmania (L.) amazonensis (promastigote) showed changes similar to those found in erythrocyte membranes. Cytotoxic effects on the parasites were also evaluated to investigate the relationships between the cytotoxic potential of MT and its ability to alter membrane fluidity. The EPR data showed that the minimum concentration of MT required to cause a change in the parasite membrane occurred near the values of MT concentration which inhibits 50 % of cell growth (IC50); thus, there is a correlation between the cytotoxicity and changes in the membrane. Although these III membrane alterations can be detected using a spin-labeled lipid, our experimental results indicated that MT interacts predominantly with the protein component of the membrane. Cell lysis was also detected by analyzing the supernatants of centrifuged samples for the presence of spin-labeled membrane fragments and cytoplasmic proteins. Using a method for the rapid incorporation of MT into the membrane, these effects were measured immediately after treatment under the same range of MT concentrations that cause cell growth inhibition. Cytotoxicity, estimated via microscopic counting of living and dead cells, indicated ∼ 70% cell death at the concentration of MT at which EPR spectroscopy detected a significant change in membrane dynamics. After this initial impact on the number of viable parasites, the processes of cell death and growth continued during the first 4 h of incubation. The EPR spectra of spin-labeled membrane-bound proteins were consistent with more expanded and solvent-exposed protein conformations, suggesting a detergent-like action. Thus, MT may form micelle-like structures around polypeptide chains, and proteins with a higher hydrophobicity may induce the penetration of hydrophilic groups of MT into the membrane, causing its rupture. / A leishmaniose cut ˆanea ´e uma doenc¸a tropical negligenciada que afetamilh˜oes de pessoas em todo mundo, representando um grave problema de sa´ude p´ublica. A miltefosina (MT) ´e um alquilfosfolip´ıdio aprovado inicialmente para tratamento de cˆancer metast ´atico e tamb´em foi licenciada para o tratamento da leishmaniose visceral, embora seu mecanismo de ac¸ ˜ao a n´ıvel molecular permanec¸a pouco compreendido. A espectroscopia de ressonˆancia paramagn´etica eletr ˆonica (RPE) do marcador de spin lip´ıdico an´alogo do ´acido este´arico (5-DSA) e do marcador de spin derivado do maleimido (6-MSL) ligado covalentemente `as prote´ınas de membrana demonstraram que a MT provoca um grande aumento na dinˆamica molecular das membranas de eritr ´ocito (ghosts) e membranas resistentes `a extrac¸ ˜ao por detergente (DRMs) preparadas a partir de membranas de eritr ´ocito. A t ´ecnica tamb´em demonstrou que em ves´ıculas formadas com lip´ıdios constituintes de rafts, 20 mol% de esfingomielina pode ser substitu´ıdo por 20 mol% de MT, sem qualquer alterac¸ ˜ao em termos de dinˆamica molecular. Al ´em disso, o efeito da MT em DRMs foi mais pronunciado do que em ghosts de eritr ´ocito, consistente com a hip´otese da MT ser um modulador de raft. Na concentrac¸ ˜ao de MT presente no plasma sangu´ıneo durante o tratamento de leishmaniose (31-52 μg/mL), as nossas medidas realizadas diretamente no sangue total indicaram um n´ıvel de 2-5% de hem´olise e tamb´em mostrou que a concentrac¸ ˜ao de MT capaz de alterar a fluidez da membrana de eritr ´ocito a n´ıvel detect ´avel pela espectroscopia de RPE causou cerca de 46% de hem´olise. Posteriormente, estudos de RPE realizados com os mesmos marcadores de spin na membrana de Leishmania (L.) amazonensis (forma promastigota) demonstraram alterac¸ ˜oes similares `as encontradas nas membranas de eritr ´ocito. Os efeitos citot ´oxicos sobre os parasitas tamb´em foram avaliados para investigar as relac¸ ˜oes entre os potenciais citot ´oxicos da MT e sua capacidade de alterar I a fluidez da membrana. Os dados de RPE demonstraram que a concentrac¸ ˜ao m´ınima necess´aria de MT para causar alterac¸ ˜ao na membrana do parasito ocorreu pr ´oximo dos valores de concentrac¸ ˜ao que inibe 50% do crescimento celular (IC50), existindo, portanto, uma correlac¸ ˜ao entre as alterac¸ ˜oes na membrana e a citotoxicidade. Embora o marcador de spin lip´ıdico tamb´em tenha detectado alterac¸ ˜oes na fluidez da membrana, os experimentos de RPE indicaram que a MT atua predominantemente no componente prot ´eico da membrana. A lise celular tamb´em foi detectada atrav´es da an´alise dos sobrenadantes das amostras centrifugadas onde foram encontrados fragmentos de membranas marcadas e tamb´em prote´ınas citoplasm´aticas. Usando um m´etodo para a r ´apida incorporac¸ ˜ao da MT na membrana, os efeitos de citotoxidade foram medidos imediatamente ap´os o tratamento e na mesma faixa de concentrac¸ ˜oes de MT que causam a inibic¸ ˜ao do crescimento celular. A citotoxicidade, estimada atrav´es da contagem microsc´opica das c´elulas vivas e mortas, indicou ∼ 70% de morte celular na concentrac¸ ˜ao de MT em que a espectroscopia de RPE detectou uma alterac¸ ˜ao significativa na dinˆamica da membrana. Ap´os o primeiro impacto no n´umero de parasitas vi ´aveis, o processo de morte e crescimento celular continuou durante as primeiras quatro horas de incubac¸ ˜ao. Os espectros de RPE de prote´ınas de membrana marcadas com o 6-MSL foram consistentes com conformac¸ ˜oes de prote´ına mais expandidas e expostas ao solvente, sugerindo uma ac¸ ˜ao t´ıpica dos detergentes. Nossa interpretac¸ ˜ao ´e que a MT pode formar estruturas semelhantes das micelas ao redor das cadeias polipept´ıdicas, expandindo as prote´ınas e que as prote´ınas com maior hidrofobicidade poderiam induzir a penetrac¸ ˜ao de grupos hidrof´ılicos da MT no interior da membrana, causando sua ruptura e consequentemente a morte da c´elula.

1. Sphingolipid-cholesterol domains (lipid rafts) in normal human and dog thyroid follicular cells are not involved in thyrotropin receptor signalling. <p>Thyroid hormone regulates growth and development throughout the animal kingdom. The thyroid which secretes it, is controlled by TSH and its receptor TSHR. TSH and its receptor TSHR act through TSHR-coupled G proteins to control thyroid functions, with a stronger coupling of the TSHR with Gs protein than with Gq protein in human thyrocytes. Gq is not activated by TSH/TSHR in dog, whereas dog TSHR activates it in CHO transfected cells. To better understand TSHR and its downstream effectors G proteins, we attempted to answer the questions by the role of “lipid rafts/caveolae” in TSH action.<p>Lipid rafts/caveolae are sphingolipids-cholesterol-enriched microdomains on plasma membrane that have been proposed to play a role in signal transduction. By concentrating the signal molecules, lipid rafts/caveolae increase the efficiency of the interactions between the molecules and sequestrate them from the bulk membranes. The compartmentation of signal proteins in lipid rafts/caveolae might provide a possible explanation for the relationship between TSHR and G proteins in human and dog thyroctyes.<p>To answer these questions, we first tested the existence of such lipid microdomains in human and dog thyrocytes. By northernblot and RT-PCR of caveolin-1 mRNA, we demonstrated its existence in thyrocytes. The immunohistochemistry of caveolin-1 showed that caveolin/caveolae are present on the apical membrane of thyrocytes, opposite to the TSHR localization on the basolateral membranes. The isolation of lipid rafts/caveolae by Triton X-100/OptiPrep density experiments showed that TSHR and Gq are not in the rafts, even though other proteins such as insulin receptor, flotillin-2 and partially Gs are present in these lipid domains, as expected. Testing the function of the TSH receptor on its main cascade (Gs-Adenylyl cyclase-cAMP) after treating the follicles with Methyl β-cyclodextrin (a cholesterol chelator), we observed no modification of the cAMP levels by this treatment. This is in agreement with our conclusion that the TSHR-Gs-cAMP pathway does not involve the lipid rafts/caveolae domain.<p>TSH-activated signalling does not take place in these membrane domains. Therefore, the differences between species, concerning the TSHR-G proteins coupling cannot be explained by the presence of these membrane domains.<p>2. Species specific thyroid signal transduction: conserved physiology, diverged mechanisms<p>As mentioned above, Gq proteins are activated in human but not in dog thyroid, in response to TSHR. However the dog TSH receptor is able to activate Gq, as demonstrated in transfected CHO cells. Thus, different thyroid signal transduction pathways exist in different species. <p>In this study, we investigated the effects of TSH on its two signal transduction cascades, the cAMP pathway and the phospholipase C – IP3 – DAG pathway, as measured by cAMP levels and inositol phosphate generation. We also measured the effects of TSH and of agents stimulating specifically one of these cascades, forskolin for the cAMP pathway and Ca++ ionophore (ionomycin) and phorbolmyristate ester (TPA) for the phospholipase C pathway, on markers of thyroid hormone synthesis (H2O2 generation and iodide binding to proteins) and on thyroid hormone secretion in vitro in the various thyroids. <p>We demonstrated that in all species investigated, the TSH receptor activates both hormone synthesis and secretion. While in some species, including humans, rats and mice, the TSH receptor activates both the cAMP and phospholipase C– IP3 – DAG cascades, in others (e.g. dog) it only stimulates the first. The cAMP pathway activates the limiting step in thyroid hormone synthesis, the generation of H2O2, in dog, rat and mice but not in human, pig, horse and beef. Thus physiology remains but the pathways to achieve it differ. On a practical point of view, these results allow to choose adequate animal models for investigating different aspects of human thyroid signalling.<p><p>3. Duoxes -TPO association and its regulation in human thyrocytes: the thyroxisome<p>Duox (Dual Oxidase) and TPO (thyroid peroxidase) are the crucial enzymes for the thyroid hormones biosynthesis (T3/T4). TPO uses the hydrogen peroxide (H2O2) produced by Duox1 and Duox2 isoenzymes to covalently link oxidized iodide to tyrosines of thyroglobulin and couple the iodinated tyrosines to form triiodothyronine (T3) and thyroxine (T4). An excess of H2O2 is considered to be toxic for cells although at appropriate concentrations H2O2 may carry out signalling functions. Even though thyrocytes show a better resistance to H2O2 than other cells, it would be beneficial for thyrocytes if Duox and TPO localize closely to increase the working efficiency and avoid an excessive H2O2 spillage. In this study, we explored the association of Duox with TPO, and the possible factors affecting their interaction in the human thyrocyte model. This association was established by co-immunoprecipitation approaches on purified plasma membranes from human thyrocytes and COS-7 transfected cells. <p>Our results show that 1) Duox and TPO localize closely at the plasma membranes of human thyrocytes, 2) this association is up-regulated through the Gq-PLC-Ca2+-PKC pathway and down-regulated through the Gs-cAMP-PKA pathway. 3) H2O2 directly increases the association of Duox and TPO. 4) Partial NH2- or COOH-terminal Duox1 and Duox2 proteins show different binding abilities with TPO in COS-7 transfected cells.<p>The association of the two proteins Duox and TPO thus supports our previous hypothesis of the thyroxisome, a pluriprotein plasma membrane complex in which elements of the iodination apparatus localize closely, thus optimizing working efficiency and minimizing H2O2 spillage. Defect in this association, independently of the catalytic efficiency of the enzyme, could therefore impair thyroid hormone synthesis and be harmful to thyroid cells, leading to thyroid insufficiency.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

Dans le cadre de ce travail de thèse, la polymérisation de type RAFT a été exploitée pour synthétiser des particules de latex magnétiques décorées de polymères stimulables. Cinq (co)polymères hydrophiles ont tout d'abord été préparés via la (co)polymérisation RAFT en solution d'acide acrylique (AA) et de méthacrylate de 2-diméthylaminoéthyle (MADAME). Les agents macromoléculaires obtenus (macroRAFT) : des homopolymères de PAA ou PMADAME ainsi que des copolymères P(AA-co-MADAME), présentent une sensibilité au pH et à la température. Ces macroRAFT hydrophiles ont ensuite été utilisés dans des réactions d’extension de chaîne avec du styrène conduisant à la formation de copolymères à blocs amphiphiles bien définis. Puis, des dispersions aqueuses d’agrégats (clusters) de nanoparticules d’oxyde de fer (OF) ont ensuite été préparées via un procédé de mini-émulsification/évaporation de solvant, en utilisant les copolymères à blocs comme stabilisants. Après optimisation des conditions expérimentales (sonication, concentration de macroRAFT, pH), des agrégats de taille contrôlée (45 à 300 nm) ont pu être obtenus. Ces clusters ont ensuite été utilisés comme semence lors de la polymérisation en émulsion du styrène, conduite en présence d’un agent de réticulation. Les clusters d'OF ont été individuellement encapsulés par une couche de polymère, formant des particules magnétiques stabilisées par le segment hydrophile des copolymères à blocs. Enfin, les particules magnétiques décorées de copolymères de P(AA-co-MADAME) ont été utilisées avec succès pour la capture et le relargage de bactéries grâce à la modulation de leurs propriétés de surface en fonction du pH / In this work reversible addition-fragmentation chain transfer (RAFT) polymerization was exploited to synthesize magnetic latex particles decorated with stimuli-responsive polymer brushes. First, five hydrophilic (co)polymers with various compositions were successfully prepared by RAFT solution (co)polymerization of acrylic acid (AA) and 2-dimethylaminoethyl methacrylate (DMAEMA) for different AA to DMAEMA molar ratios. The obtained macromolecular RAFT agents (macroRAFTs), PAA or PDMAEMA homopolymers and P(AA-co-DMAEMA) copolymers, displayed interesting pH- and thermo-responsive properties. These hydrophilic macroRAFTs were then chain extended with styrene leading to the formation of well-defined amphiphilic block copolymers. An aqueous dispersion of iron oxide clusters was next prepared using a strategy based on emulsification/solvent evaporation in which the block copolymers were used as stabilizers. By varying the experimental conditions (sonication power, macroRAFT concentration and pH of the medium), the cluster size could be controlled from 45 up to 300 nm. These clusters were then used as seeds in styrene emulsion polymerization in the presence of a crosslinker. The iron oxide clusters were individually encapsulated into a polymer shell generating latex particles, stabilized by the hydrophilic segment of the block copolymers, and displaying interesting magnetic properties. At last, these magnetic beads were evaluated as carriers in the magnetic separation of bacteria. The magnetic latex particles decorated with P(AA-co-DMAEMA) copolymers were successfully employed for the capture and trigger release of bacteria, allowing their concentration in a biological sample

Introduction Un fluide supercritique (SCF) est une substance dont la température et la pression sont à la fois au-dessus de leurs valeurs essentielles qui sont définies comme le point critique. Le point critique (Pc) désigne le point où les phases gaz, liquide et phase supercritique coexistent et il peut être observé expérimentalement par une opacité critique. Les propriétés des SCFs sont différentes de celles des liquides et des gaz ordinaires. Près de la densité critique, les SCFs affichent des propriétés qui sont dans une certaine mesure intermédiaire entre celles d'un liquide et un gaz. Parmi les fluides supercritiques, le scCO2 a certainement un excellent potentiel de développement pratique en raison de ses faibles conditions critiques (Tc = 31 °C, Pc = 74 bars), et en raison de la nature non-polaire et faible des forces de van der Waals impliquant le CO2. Les espèces hydrophiles (tels que des acides aminés, des protéines et de nombreux catalyseurs) sont souvent insolubles dans le scCO2. De toute évidence, il existe une limitation de l'application de dioxyde de carbone supercritique. Récemment, dans le but de remédier à cet inconvénient, une approche plus efficace consiste à utiliser des tensioactifs appropriés pour produire des micro-émulsions eau/CO2 ou micelles inverses. Consan et Smith ont testé la solubilité de plus de 130 agents tensioactifs disponibles dans le commerce dans le scCO2 à 50 °C et de 10 à 50 MPa. Tous sont très peu solubles ou seulement légèrement solubles dans le scCO2, de sorte qu'ils ne pouvaient pas être utilisés comme surfactants pour ce milieu. Toutefois, certains matériaux non polaires de bas poids moléculaire peuvent se dissoudre dans le scCO2, et sont utilisés avec succès pour divers procédés industriels tels que l'extraction par fluide supercritique, la chromatographie en fluide supercritique et en tant que milieu réactionnel. / Supercritical fluid is a substance whose temperature and pressure are both above their critical values which are defined as the critical point. Similarly to the triple point which defines the zero-variance point for the solid, gas and liquid states, the critical point (Pc) denotes the point where the gas, liquid and supercritical phases coexist and it can be experimentally observed through a critical opacity. Properties of SCFs are different from those of ordinary liquids and gases. Close to the critical density, SCFs display properties that are to some extent intermediate between those of a liquid and a gas. For example, a SCF may be relatively dense and dissolve certain solids while being miscible with permanent gases and exhibiting high diffusivity and low viscosity. In addition, SCFs are highly compressible and the density (and therefore solvent properties) can be "tuned" over a wide range by varying pressures and temperatures. Among supercritical fluids, scCO2 certainly has excellent potential for practical development not only because of its low critical conditions (Tc = 31 °C, Pc = 74 bar), but also due to some other factors such as: CO2 is non-toxic. Its threshold air concentration for working conditions is as high as 5000 ppm. By means of comparison, a daily exposition to 10 ppm of chloroform is considered hazardous. CO2 is non-flammable. This constitutes another very competitive advantage compared to halogenated solvents. Its high pressure vapour-superior to 60 bar-allows its complete removal from processed materials. Thus, CO2 is one of the two solvents fully approved by the Food and Drug Administration (FDA), along with water. CO2 has a low reactivity and is inert towards oxidation. It is also a non-transferring species for radicals. Heat and mass transfer are significantly enhanced in scCO2 due to its properties of low viscosity and densities. Its low surface tension allows wetting structured materials better than liquids usually do. However, besides the cost of high-pressure vessels, CO2 still has intrinsic physical disadvantages: A low cohesive energy density which confers a weak solvent strength to CO2. CO2 is a Lewis acid through its electron-deficient carbon. It thus reacts reversibly with strong Lewis bases such as primary and secondary amines. But this can be turned into an advantageous property for the capture of CO2 by amine-based solvents and surfactants, polymers and solvents that possess CO2-responsive moieties such as guanidines and amidines. CO2 is a poison for Ziegler-Natta and palladium-based catalysts due to the formation of CO. Due to the non-polar and weak Van der Waals forces of CO2, most lipophilic and hydrophilic species (such as amino acids, proteins and many catalysts) are often insoluble in scCO2. Obviously, it is a limitation for the application of supercritical carbon dioxide. Recently, in order to overcome this disadvantage, the most effective approach is to use suitable surfactants to produce water-in-CO2 microemulsions or reverse micelles. Consan and Smith tested the solubility of over 130 commercially available surfactants in scCO2 at 50 °C and 10-50 MPa. All of them were rarely soluble or only slightly soluble in scCO2, so they could not be employed as surfactants in scCO2.

Depuis le milieu du 20ème siècle, les techniques de récupération assistée du pétrole (RAP) ont été beaucoup utilisées afin d’améliorer le rendement d’extraction du pétrole brut. Des polyacrylamides modifiés hydrophobiquement ont montré des propriétés intéressantes en tant que modificateurs de rhéologie en vue d’une application en RAP. Cependant, la synthèse de polymères hydrosolubles comportant des segments hydrophobes le long de la chaîne est un défi puisque les monomères hydrophiles et hydrophobes sont rarement miscibles dans le même solvant. Le but de cette thèse a été de développer des copolymères à base d’acrylamide pouvant ensuite être utilisés en RAP. Au cours de l’extraction du pétrole, des polymères possédant des longues chaînes sont mélangés à l’eau puis injecté dans le puits afin de pousser le pétrole brut en dehors de celui-ci. Le polymère a alors pour rôle d’accroître la viscosité de l’eau de sorte qu’elle puisse déplacer plus efficacement le pétrole hors du réservoir. Au cours de cette thèse, la technique RAFT/MADIX a été combinée à la polymérisation micellaire dans le but de synthétiser de nouveaux copolymères associatifs d’architectures contrôlées et possédant de nombreux blocs hydrophobes distribués le long de la chaîne. En phase aqueuse, les segments hydrophobes s’associent et forment un réseau viscoélastique résultant en une augmentation de la viscosité. La combinaison de RAFT/MADIX avec la polymérisation micellaire nous permet également de limiter la dérive en composition observée en polymérisation micellaire conventionnelle. Dans un premier temps, l’étude de l’effet des monomères et de sels sur le comportement des micelles de tensio-actif a montré que la présence de NaAMPS gouverne le procédé de micellisation du SDS par rapport à l’acrylamide. Cette étude a également prouvé qu’il est possible de prévoir l’évolution du NH en fonction de la composition du milieu réactionnel au cours de la synthèse. La compréhension des interactions tensio-actif-monomères permet ainsi de prévoir la microstructure du polymère. Dans un second temps, il a été démontré que les polymères associatifs synthétisés ici se comportent comme des chaînes vivantes et peuvent être étendus avec de l’acrylamide pour former des polymères à bloc de haute masse molaire. L’addition d’un sel monovalent tel que le chlorure de sodium (NaCl) s’est révélée un outil efficace pour contrôler la microstructure du polymère, rendant possible le passage d’une composition de type gradient vers une composition plus homogène (rmonomères hydrophiles/tBS proche de 1). Enfin, l’analyse des relations structure-propriété a montré que tous les polymères synthétisés possèdent un comportement associatif et accroissent la viscosité de l’eau comparé à l’homopolyacrylamide. La présence de NaAMPS dans la chaîne diminue fortement la viscosité du polymère alors qu’elle n’est pas affectée par celle du chlorure de sodium. Le polymère présentant les meilleures propriétés en vue d’une application en RAP est P(Am90-co-AMPS10-co-(Am/NaCl)10-co-tBS1). L’utilisation de NaCl assure de bonnes propriétés rhéologiques tandis que le NaAMPS favorise la solubilité du copolymère en solution aqueuse. / Since the middle of the 20th century, enhanced oil recovery (EOR) techniques have been used to improve the extraction of crude oil. Hydrophobically modified polyacrylamides have shown great properties as rheology modifiers for EOR purposes. However, the synthesis of water-soluble polymers containing hydrophobic segments along the backbone is challenging as hydrophilic and hydrophobic monomers are rarely soluble in the same solvent. The aim of this project was to develop acrylamide-based copolymers for enhanced oil recovery (EOR). In this process, long chain polymer molecules are mixed with water and injected into the oil field in order to drive the oil out of the well. The polymer serves to increase the viscosity of the water, making it more effective at displacing the oil. In this thesis, RAFT/MADIX technique has been combined with micellar polymerization in order to synthesize new associative copolymers with controlled architectures and numerous hydrophobic blocks distributed along the backbone. The associations generate a viscoelastic network in aqueous media resulting in a viscosity increase. The combination of RAFT/MADIX with micellar polymerization allows us to limit the compositional drift observed in conventional micellar polymerization. First, the study of the effect of monomers and salts on the behavior of surfactant micelles has shown that the influence of NaAMPS dominates that of acrylamide in its effect on the micellization behavior of SDS. This study has proven that it is possible to predict how NH would vary depending on the composition of the reactive medium during the synthesis. Understanding the surfactant-monomer interactions thus enables prediction of the microstructure of the polymer. In a second step, it has been demonstrated that the associative polymeric chains were living chains and could be further extended to high molar masses with acrylamide. Increasing the content of NaAMPS in the hydrophilic backbone led to a significant increase in the reactivity ratio. The addition of monovalent salt (especially NaCl) is a useful tool to control the polymer microstructure, enabling switching between a gradient-type composition and a more homogeneous one (rhydrophilic monomers/tBS close to 1). Finally, the examination of structure-property relationships of the associative polymers has highlighted that all polymers displayed associating properties as well as enhanced viscosity compared to homopolyacrylamide. The polymer viscosity strongly decreased upon incorporation of NaAMPS within the backbone while it was unaffected by the presence of NaCl during the synthesis. The polymer displaying the best properties for use in EOR is P(Am90-co-AMPS10-co-(Am/NaCl)10-co-tBS1). The use of NaCl ensures good rheological properties while AMPS enhances the solubility of the copolymer.

As the largest source of iron in North America, and as the largest energy consumer in the modern integrated steel mill, the blast furnace is a critical part of modern ironmaking. Any improvements that can be made to the efficiency or emissions of the blast furnace can have far reaching environmental impacts as the production of one ton of steel results in 1.85 tons of carbon dioxide emissions. Given the concerted push to reduce greenhouse emissions, novel technologies are needed to improve efficiency. In this study the injection of preheated natural gas, precombusted syngas from a variety of feedstocks, and hydrogen injection were all modeled using computational fluid dynamics, from the tuyere through the shaft of the furnace. The impacts of these various operational changes were evaluated using CFD calculated analogs for Raceway adiabatic flame temperature (RAFT), top gas temperature (TGT), and coke rate (CR). Results indicate that a reduction of 3% to 12% in CO2 emissions is possible through the implementation of these technologies, with each possessing distinct benefits and drawbacks for industrial implementation.