La régénération des défauts osseux de taille critique reste un défi majeur pour la santé. Les limitations des greffes de tissus communes nous ont incités à développer une alternative synthétique basée sur la construction d’un biomatériau, des facteurs ostéoinductifs et des cellules souches. Pour la construction du biomatériau, nous nous sommes concentrés sur les microporteurs polymères poreux, car ils supportent une expansion cellulaire à grande échelle et un assemblage modulaire des tissus, contournant deux goulots d'étranglement importants pour la traduction clinique. Pour assurer l'approvisionnement industriel et l'approbation réglementaire, nous avons conçu une méthode de fabrication sans solvant organique basée sur la cristallisation sphérulitique du poly(L-lactide) (PLLA) dans ses mélanges avec du polyéthylène glycol (PEG). Les sphérulites de PLLA ont été facilement récupérées sous forme de microporteurs en éliminant par rinçage le PEG soluble dans l'eau. Leur taille et leur porosité pourraient être contrôlées indépendamment en ajustant le rapport PLLA / PEG et la température de cristallisation. La biocompatibilité et l'ostéoconductivité des microporteurs à PLLA ont été confirmées par l'expansion et la différenciation ostéogénique des cellules souches adipeuses humaines (hASC). Comme cette dernière fonction hASC est sensible à différents paramètres de culture, nous avons ensuite utilisé l'approche de conception d'expériences pour leur dépistage rapide. En combinaison avec l'analyse à haut débit, nous avons identifié plusieurs paramètres ayant une influence marquée sur leur différenciation ostéogénique. Enfin, pour la délivrance de facteurs ostéoinducteurs, nous avons élaboré des multicouches de polyélectrolytes (PEM) à base de poly (L-ornithine) et d'acide hyaluronique biocompatibles. Ces PEM ont été caractérisées en termes de croissance, de morphologie, d'aptitude à incorporer des protéines morphogénétiques osseuses (BMP) et à fonctionner en tant que revêtements sur des microporteurs à PLLA. Nos résultats préliminaires ont montré que l’incorporation de BMP dans les PEM avait un effet important sur l’adhérence des hASC. Bien que des études supplémentaires soient nécessaires, les microporteurs à PLLA recouverts de PEM chargés de BMP et ensemencés avec hASC pourraient être un implant synthétique prometteur pour une régénération osseuse améliorée. / The regeneration of critical-sized bone defects remains a major healthcare challenge. The limitations of common tissue grafts prompted us to develop a synthetic alternative based on a biomaterial construct, osteoinductive factors and stem cells. For biomaterial construct, we focused on porous polymeric microcarriers as they support large-scale cell expansion and modular tissue assembly, circumventing two important bottlenecks for clinical translation. To insure industrial supply and regulatory approval, we designed an organic-solvent-free method for their fabrication based on the spherulitic crystallization of poly(L-lactide) (PLLA) in its blends with polyethylene glycol (PEG). The PLLA spherulites were easily recovered as microcarriers by rinsing away the water-soluble PEG. Their size and porosity could be independently controlled by tuning the PLLA/PEG ratio and crystallization temperature. The biocompatibility and osteoconductivity of PLLA microcarriers were confirmed through the expansion and osteogenic differentiation of human adipose stem cells (hASCs). Because the latter hASC function is sensitive to different culture parameters, we then used the Design of Experiments approach for their rapid screening. In combination with high-throughput analysis, we identified several parameters that had a pronounced influence on their osteogenic differentiation. Finally, for the delivery of osteoinductive factors, we elaborated polyelectrolyte multilayers (PEM) based on biocompatible poly(L-ornithine) and hyaluronic acid. These PEMs were characterized in terms of their growth, morphology, the ability to incorporate bone morphogenetic proteins (BMP) and to function as coatings on PLLA microcarriers. Our preliminary results showed that the incorporation of BMPs inside PEMs had a strong effect on hASC adhesion. While further studies are needed, hASC-seeded PLLA microcarriers coated with BMP-loaded PEMs could be a promising synthetic implant for improved bone regeneration.

Polyamideamine epichlorohydrin (PAE) resin is a water soluble additive and the most used permanent wet strength additive in alkaline conditions for preparing wet strengthened papers. In this thesis, we studied some properties of PAE resins and wet strengthened papers prepared from them. In order to elucidate PAE structure, liquid state, 1H and 13C NMR was performed and permitted signals assignment of PAE structure. PAE films were prepared to study cross-linking reactions and then thermal and ageing treatments were performed. According to our results, the main PAE cross-linking reaction occurs by a nucleophilic attack of N atoms in the PAE and/or polyamideamine structures forming 2-propanol bridges between PAE macromolecules. A secondary contribution of ester linkages to the PAE cross-linking was also observed. However, this reaction, which is thermally induced, only occurs under anhydrous conditions. The mechanism related to wet strength development of PAE-based papers was studied by using CMC as a model compound for cellulosic fibres and PAE-CMC interactions as a model for PAE-fibres interactions. Based on results from NMR and FTIR, we clearly showed that PAE react with CMC that is when carboxylic groups are present in great amounts. Consequently, as the number of carboxylic groups present in lignocellulosic fibres is considerably less important and the resulting formed ester bonds are hydrolysable, we postulate that ester bond formation has a negligible impact on the wet strength of PAE-based papers. In the second part of this work, a 100% Eucalyptus pulp suspension was used to prepare PAE-based papers. PAE was added at different dosages (0.4, 0.6 and 1%) into the pulp suspension and its adsorption was indirectly followed by measuring the zeta potential. Results indicate that the adsorption, reconformation and/or penetration phenomena reach an apparent equilibrium between 10 and 30 min. Moreover, we showed that the paper dry strength was not significantly affected by the conductivity level (from 100 to 3000 µS/cm) of the pulp suspension. However, the conductivity has an impact on the wet strength and this effect seems to be enhanced for the highest PAE dosage (1%). We also demonstrated that storing the treated paper under controlled conditions or boosting the PAE cross-linking with a thermal post-treatment does not necessarily lead to the same wet strength. Degrading studies of cross-linked PAE films showed that PAE degradation in a persulfate solution at alkaline medium was more effective. A preliminary study of industrial PAE-based papers (coated and uncoated papers) was also performed. For uncoated paper, persulfate treatment was the most efficient. For coated papers, all treatments were inefficient in the used conditions, although a decrease of the wet tensile force of degraded samples was observed. The main responsible of the decrease of persulfate efficiency for coated papers was probably related to side reactions of free radicals with the coating constituents.

This dissertation presents chemical sensors that are based on an emerging optical fiber sensing technology for the determination of the presence and concentration of hydrogen peroxide (H2O2) at low concentrations. The motivation to determine hydrogen peroxide lies on the fact that this chemical species is generated as a by-product of the operation of hydrogen-based polymer electrolyte membrane fuel cells (PEMFCs), and the presence and formation of this peroxide has been associated with the chemical degradation that results in low durability of PEMFCs. Currently, there are no techniques that allow the hydrogen peroxide to be determined in situ in PEMFCs in a reliable manner, since the only report of this type of measurement was performed using electrochemical techniques, which can be affected by the environmental conditions and that can alter the proper operation of the PEMFCs. The sensors presented in this dissertation are designed to detect the presence and quantify hydrogen peroxide in solution at the conditions at which PEMFCs operate. Since they are made using fused silica optical fibers and are based on a spectroscopic technique to perform the detection of H2O2 , they are not affected by the electromagnetic fields or the harsh chemical environment inside PEMFCs. In addition, they are able to still detect the presence of H2O2 at the operating temperatures. The construction of the sensing film on the tip of an optical fiber and its small size (125 µm diameter), make the sensors here developed an ideal solution for being deployed in situ in PEMFCs, ensuring that they would be minimally invasive and that the operation of the fuel cell would not be compromised by the presence of the sensor. The sensors developed in this dissertation not only present design characteristics that are applicable to PEMFCs, they are also suitable for applications in other fields such as environmental, defense, and biological processes. / Graduate / 0548 / 0756 / 0791 / jfbotero@gmail.com

This dissertation presents chemical sensors that are based on an emerging optical fiber sensing technology for the determination of the presence and concentration of hydrogen peroxide (H2O2) at low concentrations. The motivation to determine hydrogen peroxide lies on the fact that this chemical species is generated as a by-product of the operation of hydrogen-based polymer electrolyte membrane fuel cells (PEMFCs), and the presence and formation of this peroxide has been associated with the chemical degradation that results in low durability of PEMFCs. Currently, there are no techniques that allow the hydrogen peroxide to be determined in situ in PEMFCs in a reliable manner, since the only report of this type of measurement was performed using electrochemical techniques, which can be affected by the environmental conditions and that can alter the proper operation of the PEMFCs. The sensors presented in this dissertation are designed to detect the presence and quantify hydrogen peroxide in solution at the conditions at which PEMFCs operate. Since they are made using fused silica optical fibers and are based on a spectroscopic technique to perform the detection of H2O2 , they are not affected by the electromagnetic fields or the harsh chemical environment inside PEMFCs. In addition, they are able to still detect the presence of H2O2 at the operating temperatures. The construction of the sensing film on the tip of an optical fiber and its small size (125 µm diameter), make the sensors here developed an ideal solution for being deployed in situ in PEMFCs, ensuring that they would be minimally invasive and that the operation of the fuel cell would not be compromised by the presence of the sensor. The sensors developed in this dissertation not only present design characteristics that are applicable to PEMFCs, they are also suitable for applications in other fields such as environmental, defense, and biological processes. / Graduate / 0548 / 0756 / 0791 / jfbotero@gmail.com

A busca por materiais que possam ser modificados em nível molecular tem sido o alvo de numerosas pesquisas no mundo. Desta maneira, as técnicas de fabricação de filmes finos se destacam devido à possibilidade de se reduzir custos e melhorar a eficiência de sistemas como, por exemplo, os fotossensíveis. Neste contexto, o objetivo deste trabalho foi a obtenção e caracterização de filmes finos através da técnica de automontagem (técnica "camada por camada" ou Layer-by-Layer). Os filmes foram depositados sobre diversos substratos (lamínula de vidro, silício e poliestireno). Nesse trabalho foram depositados dois conjuntos diferentes de multicamadas combinados com duas proporções diferentes de cada sistemas de soluções. O sistema catiônico foi composto pela solução do polieletrólito orgânico PDDA e a solução coloidal do semicondutor inorgânico seleneto de cádmio (CdSe). O sistema aniônico foi composto por solução do poli(ácido acrílico) (PAA) e solução de óxido de titânio (TiO2), respectivamente. Os materiais utilizados para a obtenção dos filmes e os filmes finos nanoestruturados produzidos foram caracterizados por meio de diversas técnicas. As regiões de absorção das soluções coloidais inorgânicas foram determinadas por espectroscopia de absorção molecular no ultravioleta-visível (UV-Vis) e apresentaram absorção em 320 nm (TiO2) e 440 nm (CdSe). O diâmetro das nanopartículas inorgânicas de TiO2 e de CdSe foram mensurados por difração de raios X (DRX) e microscopia eletrônica de transmissão (MET), revelando valores em escala nanométrica. Observou-se no difratograma do pó nanoparticulado de TiO2 que a fase predominante no mesmo é a anatase, e que houve uma sobreposição dos picos de maior intensidade do TiO2 e do CdSe, ambos em 2q = 25,3°. O espectro de refletância difusa (RDUV-Visível) dos filmes automontados apresentou valores compatíveis com as das soluções formadoras dos filmes, indicando que os mesmos apresentam aplicação em dispositivos fotossensíveis. Através dos comprimentos de onda obtidos a partir das técnicas de UV-Vis e RDUV-Vis foi possível estimar os valores de energia de bandas proibidas (Ebg) para os semincondutores TiO2 e CdSe. As espessuras dos filmes foram determinadas pelas técnicas de perfilometria e por microscopia eletrônica de varredura (MEV), e encontram-se na ordem de grandeza micrométrica. Pelas micrografias de MEV foi possível avaliar a superfície dos filmes que revelaram alta rugosidade, formação de ilhas de TiO2 e aglomeração de grãos esféricos (Se). Nas imagens de MET, observou-se a distribuição das nanopartículas dos semicondutores na seção transversal dos filmes, corroborando as aglomerações observadas por MEV. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-05T16:53:57Z No. of bitstreams: 1 Dissertacao Ana Claudia R Faria.pdf: 12916246 bytes, checksum: 8f6d72e15170865b53f4fc6c7da263b1 (MD5) / Made available in DSpace on 2014-06-05T16:53:57Z (GMT). No. of bitstreams: 1 Dissertacao Ana Claudia R Faria.pdf: 12916246 bytes, checksum: 8f6d72e15170865b53f4fc6c7da263b1 (MD5) / The search for materials that can be modified at molecular level has been the subject of several studies worldwide. Thus, the production techniques of thin films stand out due to the possibility of reducing costs and improving the efficiency of systems, such as photosensitive systems. In this context, the aim of this study was to obtain and characterize thin films using the self-assembly technique (layer by layer technique or LbL). The thin films were deposited on different substrates (glass coverslips, silicon and polystyrene). In this work two different multilayer sets combined with two different proportions of each solution system were deposited. The cationic system was composed by the poly(diallyldimethilammonium) (PDDA) organic polyelectrolyte solution and the cadmium selenide (CdSe) inorganic semiconductor colloidal solution. The anionic system was composed by the poly(acid acrylic) (PAA) solution and the titanium dioxide (TiO2) solution, respectively. The materials used for the achievement of films and nanostructured thin films produced were characterized through various techniques. The absorption regions of inorganic colloidal solutions were determined by UV-Vis spectroscopy and presented absorption at 320 nm (TiO2) and 440 nm (CdSe). The resulting inorganic nanoparticles diameter of TiO2 and CdSe were measured by X ray diffraction (XRD) and transmission electron microscopy (TEM), resulting in values at nanometric scale. It was observed in the nanoparticle TiO2 powder diffractogram that anatase is the most abundant phase, and that there was an overlap of the highest intensity diffraction peaks of TiO2 and CdSe, both at 2q = 25.3 °. The diffuse reflectance spectrum (RDUV-Vis) of self-assembled films presented values compatible with those of the film forming solutions. Using the wavelengths obtained from the UVVis and Vis-RDUV techniques it were possible to evaluate values for the energy band gap (Ebg) seminconductors TiO2 and CdSe. The thicknesses of the films were determined by profilometry and scanning electron microscopy (SEM) techniques, and they are in the micrometric order of magnitude. Using the SEM micrographs, it was possible to evaluate the surface of the films that show a high roughness, the formation of TiO2 clumps and the agglomeration spherical selenium clusters. In TEM images, the distribution of the semiconductor nanoparticles in cross-section of films can be observed, confirming agglomerations observed by SEM.

Submitted by Daniel Lucas Zago Caetano (daniel.caetano@sjrp.unesp.br) on 2017-09-29T00:38:30Z No. of bitstreams: 1 caetano_dlz_dr_sjrp.pdf: 13957655 bytes, checksum: 5b96587e7372ab57b53df4f703a1de39 (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-09-29T18:31:12Z (GMT) No. of bitstreams: 1 caetano_dlz_dr_sjrp.pdf: 13957655 bytes, checksum: 5b96587e7372ab57b53df4f703a1de39 (MD5) / Made available in DSpace on 2017-09-29T18:31:12Z (GMT). No. of bitstreams: 1 caetano_dlz_dr_sjrp.pdf: 13957655 bytes, checksum: 5b96587e7372ab57b53df4f703a1de39 (MD5) Previous issue date: 2017-09-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho tem por objetivo estudar, por meio de simulações computacionais baseadas no método de Monte Carlo, interações eletrostáticas em superfícies e macromoléculas. Na primeira parte deste estudo é abordada a interação entre polieletrólitos, mais especificamente, homopolímeros e copolímeros em bloco suscetíveis à variações de pH, e macromoléculas com distribuição helicoidal de carga compatível com a encontrada em polinucleotídeos. A macromolécula foi representada por um cilindro rígido infinito que simula a parte central do DNA/RNA, totalmente inacessível ao polieletrólito. Visando simular os sulcos do DNA, duas esferas completam o modelo: uma localizada na posição dos grupos fosfato (esfera externa) e outra localizada entre a esfera externa e o cilindro (esfera interna). A distribuição de carga da macromolécula é dada por um conjunto de cargas negativas monovalentes centradas nas esferas externas. O polieletrólito foi representado por uma cadeia de N esferas rígidas carregadas, conectadas por um potencial harmônico e com um valor de pKa específico. A solução eletrolítica foi tratada pela teoria de Debye-Hückel. Os efeitos do pH, da concentração de sal, da estrutura primária e da rigidez da cadeia polimérica e da distribuição de carga da macromolécula sobre as propriedades conformacionais e físico-químicas da cadeia adsorvida foram calculados. Verificou-se que a presença da macromolécula modifica as propriedades ácido/base do polieletrólito e que o efeito de regulação de carga afeta o processo de adsorção/dessorção. Além disso, constatou-se uma dependência entre as conformações adotadas pelo polieletrólito na superfície da macromolécula e a concentração de sal da solução. Na segunda parte deste trabalho é investigada a influência das interações de hidratação sobre a capacitância diferencial da dupla camada elétrica por meio de simulações de Monte Carlo e por modelos teóricos baseados na aproximação de Campo Médio. Um eletrodo plano e carregado foi inserido em uma solução eletrolítica constituída por íons monovalentes e com concentração próxima às condições fisiológicas. As interações de hidratação foram descritas por meio de potenciais de Yukawa, as quais foram adicionadas às interações de Coulomb e de volume excluído entre os íons e entre os íons e o eletrodo. O modelo de Campo Médio proposto não só inclui interações de hidratação aos pares ânion-ânion, ânion-cátion e cátion-cátion de intensidades arbitrárias, mas também leva em consideração o tamanho finito dos íons por meio de duas abordagens distintas: i) equação de estado de Carnahan-Starling; e ii) modelo de rede. A capacitância diferencial obtida não só pelas simulações de Monte Carlo, mas também pelas aproximações de Campo Médio, apresenta o característico pico duplo, usualmente denominado de camel-shape, no qual seu decaimento reflete o empacotamento dos contraíons nas proximidades do eletrodo. Verificou-se também que a presença das interações de hidratação entre os íons e entre o eletrodo e os íons promove o surgimento de uma pequena região de depleção de carga nas proximidades do eletrodo, similar à camada de Stern. / This work aims to analyze electrostatic interactions on surfaces and macromolecules through the use of computational simulations based on the Monte Carlo method. In the first part of this study, we discuss the interaction between polyelectrolytes – more specifically homopolymers and block-copolymers which are susceptible to variations in pH – and macromolecules with helical charge distribution compatible with that found in polynucleotides. The macromolecule was represented by an infinite rigid cylinder, which mimics the central core of RNA/DNA, totally inaccessible to the polyelectrolyte. In order to simulate DNA grooves, two additional spheres complete the model: one being centered at the position of the phosphate groups (outer sphere) and the other being located between the outer sphere and the cylinder (inner sphere). The charge distribution of the macromolecule is given by a helical set of monovalent negative charges centered at the outer spheres. The polyelectrolyte was represented by a chain with charged hard spheres connected by harmonic bonds and presenting a specific pKa value. The electrolyte solution was treated at the Debye-Hückel level. The effects of pH, salt concentration, primary structure and stiffness of the polymer chain on the conformational and physicochemical properties of the adsorbed chain were investigated. Results show that the presence of the macromolecule modifies the acid/base properties of the polyelectrolyte and that the effect of charge regulation affects the adsorption/desorption process. Furthermore, a dependence between the conformations adopted by the polyelectrolyte on the surface of the macromolecule and the salt concentration of the solution was also observed. In the second part of this study, we investigated the influence of hydration interactions on the differential capacitance of an electric double layer by means of Monte Carlo simulations and by theoretical models based on mean-field approximation. A charged planar electrode was inserted in an electrolyte solution composed of monovalent ions and with concentration close to that found at physiological conditions. The hydration interactions were modeled through Yukawa potentials, which were added to Coulomb and excluded volume interactions among the ions and between the ions and the electrode. The proposed mean-field model not only include hydration interactions to the cation-cation, anion-anion and cationanion pairs, but also take into account the finite size of the ions through two distinct approaches: i) the Carnahan-Starling equation of state, and ii) the lattice gas model. We found that both our Monte Carlo simulations and mean-field approaches predict a characteristic double-peak (the so-called camel shape) of the differential capacitance, where its decrease reflects the packing of the counterions near the electrode. We also found that the presence of hydration interactions among the ions and between the ions and the electrode promotes the emergence of a small region of charge depletion near the electrode, similar to the Stern layer. / FAPESP: 2013/13151-7

O presente trabalho teve como objetivo o estudo da potencialidade de aplicação da flotação por ar dissolvido (FAD) lamelar (de alta taxa) e convencional como parte final de sistema de tratamento sequencial de esgoto sanitário, constituído de reatores anaeróbios de manta de lodo (UASB) seguidos de tanque de aeração. O trabalho, desenvolvido na Estação de Tratamento de Esgotos Jardim das Flores da cidade de Rio Claro, foi dividido em três etapas. Na primeira etapa, realizada com equipamento Flotateste, foram investigados os valores mais adequados de dosagens de polímero sintético catiônico, amido de araruta, cloreto férrico e associações entre cloreto férrico e polímero ou amido de araruta, de razão ar/sólidos (A/S), bem como de tempo e gradiente de mistura rápida e de floculação. Nessa etapa, os melhores desempenhos da FAD foram obtidos com o emprego de polímero catiônico, tanto isoladamente quanto associado ao cloreto férrico, sendo esta última condição imprescindível para maior remoção de fósforo. A flotação de liquor misto utilizando apenas o cloreto férrico como coagulante, apresentou desempenho extremamente insatisfatório, com a formação de flocos com características ruins de flotabilidade. Além disso, observou-se que a flotação desse tipo de efluente requisitou condições mais amenas de mistura, sendo que, em muitos casos, os melhores resultados foram obtidos mediante a eliminação da mistura rápida ou da floculação. Nas segunda e terceira etapas, realizadas com unidades piloto de flotação lamelar de alta taxa (FADAT) e convencional, respectivamente, e empregando apenas polímero como auxiliar de floculação/flotação (dosagem em torno de 1 g de polímero/kg de SST), foram investigados os valores mais adequados de Taxa de Aplicação Superficial (TAS), Taxa de Aplicação de Sólidos (TS) e quantidade de ar fornecida à flotação, calculada através da razão A/S ou da dosagem de ar (Dar), em g de ar/'M POT.3' de esgoto afluente, dependendo da concentração de sólidos suspensos totais afluentes à flotação (SSTafl). Através dos resultados dos ensaios pôde-se observar que a razão A/S é mais adequada para o cálculo da quantidade de ar na flotação de suspensões concentradas (SSTafl acima de 1100 mg/L no presente estudo), ao passo que Dar é mais representativo no caso da flotação de suspensões diluídas. Empregando a unidade FADAT, alimentada com liquor misto de tanque de aeração em boas condições de biofloculação, foi possível obter resultados satisfatórios para TAS de até 350 'M POT.3'/'M POT.2'.dia e TS entre 120 e 250 kg de SST/'M POT.2'.dia, desde que fornecida quantidade adequada de ar ao processo (Dar na faixa de 15,0 a 18,0 g de ar/'M POT.3' de afluente), para SSTafl entre 800 e 1100 mg/L. Na flotação lamelar de alta taxa, constatou-se que o bom desempenho esteve diretamente relacionado a baixos valores de SSTafl. As recomendações para a flotação com unidade de FAD convencional tiveram que ser mais conservadoras, devido às condições ruins de biofloculação apresentadas pelo liquor misto do tanque de aeração durante a realização da terceira etapa do trabalho. Nesses ensaios, os resultados mais satisfatórios foram obtidos com o emprego de TAS em torno de 200 'M POT.3'/'M POT.2'.dia, TS menor que 200 kg de SST/'M POT.2'.dia e A/S em torno de 0,020 (Dar de 21,0 g de ar/'M POT.3' de afluente), para SSTafl em torno de 1400 mg/L / The aim of this research was the study of the lamella design (high rate) and conventional dissolved air flotation (DAF) process potentiality of application as the final part of a domestic sewage sequential treatment system made up anaerobic reactors (UASB) followed by aeration tank. The work, developed at the Jardim das Flores WWTP of Rio Claro city, was separated in three phases. In the first phase, using the flotatest apparatus, the most suitable values of chemical (synthetic cationic polymer, arrow-root starch, ferric chloride and ferric chloride combined with polymer or arrow-root starch) dosages, air to solids ratio (A/S), as well as rapid mix and flocculation time and mean velocity gradient values, were investigated. In this phase, the best DAF performances were obtained with the application of cationic polymer, alone and associated to ferric chloride. The use of ferric chloride was essential to obtain better phosphorus removal results. The mixed liquor flotation using ferric chloride alone as primary coagulant presented extremely unsatisfactory performance, with the formation of flocks showing bad characteristics of flotability. Moreover, it was observed that flotation of this kind of effluent had requested gentler mixture conditions. In many cases, the best results were obtained by means of rapid mix or flocculation step elimination. In the second and third phases, using the lamella design and conventional flotation units respectively and cationic polymer as the only flocculation/flotation aid (dosage around 1 g of polymer/kg TSS), the most suitable values of Overflow Rate (OR), Solids Application Rate (SAR) and amount of air supplied to the flotation process, expressed as the A/S ratio or air dosage (AD, in g of air/'M POT.3' of influent) depending on influent total suspended solids concentration (TSSinfl), were investigated. The flotation essays results showed that the A/S ratio is more suitable for the air supply estimation in flotation of concentrated suspensions (TSSinfl above 1100 mg/L in this study). Contrarily, the parameter AD is more representative in cases of flotation of diluted suspensions. Using the lamella design unit, fed with aeration tank mixed liquor presenting good bio-flocculation conditions, it was possible to obtain adequate results applying OR as high as 350 'M POT.3'/('M POT.2'.day) combined with SAR values between 120 and 250 kg of TSS/('M POT.2'.day), since the adequate amount of air has been provided for the process (AD values between 15,0 and 18,0 g of air/'M POT.3' of influent), for TSSinfl between 800 and 1100 mg/L. For the lamella flotation, it was noticed that the best performance has been directly associated to lower values of TSSinfl. The recommendations for flotation using the conventional DAF unit had to be more conservative, taking into account the poor bio-flocculation conditions presented by the mixed liquor during the third phase of work. In theses essays, the more adequate results were obtained by applying OR around 200 'M POT.3'/('M POT.2'.day), SAR under 200 kg of TSS/('M POT.2'.day) and A/S ratio around 0,020 (AD of 21,0 g of air/'M POT.3' of influent), for TSSinfl around 1400 mg/L

No description available.

Notre projet vise la conception d’un biocapteur ultra-sensible à base de bactéries pour la détection de métaux lourds (contrôle environnemental). Ces travaux concernent le développement de systèmes impédimétriques et à ondes acoustiques de Love, associés à une puce microfluidique et fonctionnalisés par des bactéries Escherichia coli immobilisées sur une multicouche de polyélectrolytes déposés par la méthode « Layer by Layer » . L’ étude fondamentale des interactions physiques-chimiques-biologiques mises en jeu lors des étapes de fonctionnalisation du capteur, et de son application à la détection de cadmium et de mercure, est également abordée, à travers le suivi en temps réel par le capteur acoustique, ainsi que par microscopie à force atomique en milieu sec ou liquide.Des seuils de détection inférieurs à 10-12M en quelques minutes ont été observés. / Our works aim the study of an ultra-sensitive bacteria-based biosensor for the detection of heavy metals (environmental control). They include the development of impedimetric and of Love acoustic wave devices, both associated with a microfluidic chip and functionalized with Escherichia coli immobilized on a polyelectrolyte multilayer deposited by the method "Layer by Layer." The theoretical study of physico-chemical interactions and biological phenomena involved during the steps of functionalization of the sensor surface, and during its application to the detection of cadmium and mercury, is also addressed through the real-time monitoring by the acoustic sensor and by atomic force microscopy in air or liquid medium. Detection threshold better than10-12M within only a few minutes have been observed.

Depuis plusieurs années, une nouvelle génération de matériaux appelés “matériaux intelligents” et définis par leur capacité d’adaptation à leur environnement, est intensément développée. Des systèmes sensibles à différents stimuli tels que le pH, la lumière, ou encore une force mécanique, impliquée dans un grand nombre de processus naturels, comme l’adhésion et la prolifération cellulaire, ont été rapportés. Ce travail de thèse a ainsi été dédié au développement de matériaux mécano-sensibles. Plus précisément de matériaux transformant une contrainte mécanique en un signal chimique, en mimant le processus physique utilisé par la nature, à savoir des changements conformationnels de protéines. Nous avons donc cherché à atteindre ce but en greffant covalemment des protéines ou des enzymes sur un substrat élastomère. Etirer le substrat devant induire des modifications de structure des protéines, conduisant ainsi à des modulations de leurs propriétés. / Since many years, a new generation of materials called « smart materials » and defined by their capacity to adapt to their environment is intensively developed. Systems sensitive to different stimuli such as pH, light or ionic strength have been reported. One of these stimuli can also be a mechanical force which is involved in many reactions in nature such as, cells adhesion and proliferation, tissues growing or even plants developments. The aim of my thesis was dedicated to the elaboration of mechano-responsive materials. More precisely, materials that transform a stretching constraint into a chemical signal by mimicking the physical processes used by nature, namely protein conformational changes. We planned to achieve this goal by covalently grafting proteins or enzymes onto a stretchable substrate or incorporating them into cross-linked polymer networks. Stretching these materials should induce protein conformational changes leading to modifications of their properties.