DMagister Scientiae - MSc / The proton exchange membrane is one key component of direct methanol fuel cells, which has double functions of conducting protons, separating fuels and oxidant. At present, the performance and price of sulfonic acid proton exchange membrane used in direct methanol fuel cells are deeply concerned. In order to reduce membrane 's cost and improve performance of Nafion membrane, three different kinds of membranes have been studied in this thesis. These membranes are SPEEK membranes, SPEEK/ZP composite membranes and Nafion/ZP composite membranes. / South Africa

Contexte: La cardiopathie ischémique (IHD) reste une cause majeure de mortalité en Amérique du Nord. La thérapie cellulaire cardiaque (CCT) a émergé comme une thérapie prometteuse pour aider à guérir certaines malades cardiaques. Parmi les cellulaires avec propriétés pluripotentes, les cellules stromales mésenchymateuses (MSC) sont prometteuses. Cependant, plusieurs questions demeurent non résolues et certaines défis empêchent l'application clinique de la CCT se dans l'IHD, tels que le faible taux de rétention cellulaire in situ, le suivi des cellules in vivo post-implantation et post-acheminements et l`apoptose. Ici, le traitement préliminaire des MSC avec des facteurs de croissance et leur couplage avec des nanoparticules (NP) seront étudiés comme des méthodes pour optimiser MSC. Méthodes: Des MSCs provenant du rat (rMSC) et du cochon (pMSC) ont été isolés à partir de moelle osseuse. Les rMSC ont été préconditionnées avec SDF-1a, TSG-6 et PDGF-BB, et ensuite soumises à une hypoxie, une privation de sérum et a un stress oxydatif. Des études de cicatrisation ont également été effectués avec rMSCs préconditionnées. En parallèle, de nouvelles NP ferromagnétiques liées aux silicones ont été synthétisées. Les NPs ont été couplées aux pMSCs suivant leur fonctionnalisation avec l`anticorps, CD44, un antigène de surface du MSC bien connu. Par la suite, les études de biocompatibilité ont été réalisées sur pMSC-NP et en incluant des tests des processus cellulaires tels que la migration, l'adhésion, la prolifération et les propriétés de la différenciation. Résultats: Parmi toutes les cytokines testées, PDGF-BB a démontré la plus grande capacité à améliorer la survie de MSC dans des conditions d'hypoxie, de privation de sérum et en reponse au stress oxydatif. La conjugaison de NP a atténué la migration et la prolifération des pMSCs, mais n`a pas changé leur capacité de différenciation. Enfin, la complexe du MSC-NP est détectable par IRM. Conclusion: Nos données suggèrent que de nouvelles stratégies, telles que traitement préliminaire de PDGF-BB et le couplage des nanoparticules ferromagnétiques, peuvent être considérés comme des avenues prometteuse pour optimiser les MSCs pour la CCT. / Background: Ischemic heart disease (IHD) remains a leading cause of mortality in North America. Cardiac cell therapy (CCT) has emerged as a promising therapy to help heal the damaged heart. Among the various candidates for stem-progenitor cells, Mesenchymal Multipotential Stromal/Stem Cells (MSC) is of great promise. However, there remain unresolved issues and challenges that prevent clinical application of MSC-based CCT in IHD. Among the latter, low cellular retention rate, in vivo cell tracking and post-delivery apoptosis. Here in, growth factor preconditioning and MSC coupling to nanoparticles are investigated as methods to optimize MSC. Methods：Lewis Rat MSC (rMSC) and pig MSC (pMSC) were isolated from bone marrow. Rat MSCs were preconditioned with SDF-1a, TSG-6 and PDGF-BB, and then subjected to hypoxia, serum deprivation and oxidative stress. Wound healing assays were also done with preconditioned rat MSCs. In parallel, novel ferromagnetic silicone core-shell nanoparticles (NP) were synthesized. Pig MSCs were coupled to NPs following functionalization of the NPs with an antibody to a well-recognized MSC surface antigen, CD44. Subsequently, biocompatibility studies were performed on the pMSC-NP complex and included testing of key cellular processes such as migration, adhesion, proliferation and differentiation properties. Results: Of all cytokines used, PDGF-BB showed greatest capacity to improve MSC survival under conditions of hypoxia, serum deprivation and oxidative stress. NP conjugation has mitigated effect on the migration and proliferation of pig MSC, but do not change the differentiation capacity of MSC. Finally, the MSC-NP complex was detectable by MRI. Conclusion: Our data suggest that novel strategies, such as PDGF-BB preconditioning and ferromagnetic nanoparticle coupling, can be considered as promising avenues to optimize MSCs for CCT.

The application of ICP-MS to the fields of proteomics and genomics has arisen in part due to its ability to detect and quantify trace levels of S and P, which are major constituents in proteins and nucleic acids respectively. The development of collision/reaction cell technology and high resolution instruments has enabled these biologically important elements to be measured and quantified at the pg - ng ml-1 level. Despite these advances, the detection limits of P and S are still inferior compared to other elements. Oligonucleotides containing biotin functionality were labelled with Au nano-particles attached to a streptavidin protein to achieve site specific labelling, with 100% labelling efficiency. Each nano-particle contained ~86 Au atoms, resulting in an 882 fold signal enhancement for 24 base length oligonucleotides. However, this enhancement factor was only observed when one oligonucleotide bound to one nano-particle in a 1:1 ratio. Much lower Au labelling efficiencies and signal enhancements were observed when thiolated oligonucleotides were labelled with maleimide functionalised gold nano-particles. This was attributed to the extensive and difficult sample preparation steps that were required prior to labelling. The detection and quantification of adducts formed between DNA and the Pt anti-cancer drugs cisplatin and oxaliplatin were also investigated with ICP-MS. Acid digestion of the carbon based DNA matrix enabled Pt adducts to be quantified at low dose rates of 1 Pt atom per 1 500 000 nucleotides in ~12 μg DNA. Such sensitive mass spectrometric determinations could be employed in clinical tests to detect and quantify low level adducts formed in patients in-vivo. To complement ICP-MS analysis, electrospray ionisation linear ion trap mass spectrometry was employed to study the interaction of oxaliplatin with the four DNA nucleobases. Multiple stage mass spectrometry enabled detailed Pt-nucleobase adduct fragmentation pathways to be established. The method of DNA detection using P in conjunction with the collision cell, or cool plasma to form PO+ was also demonstrated and the limitations of the method, namely, polyatomic interferences and severe matrix effects were highlighted.

In this Thesis experimental studies of nano-clusters using synchrotron radiation based photoelectron (UPS and XPS) and Auger Electron Spectroscopy (AES) are presented. The investigations may be divided into two parts where the first reports on the structure of heterogeneous two component clusters, and the second concerns electronic decay processes. Using photoelectron spectroscopies as investigative tools the radial composition of heteroclusters of argon mixed with xenon, krypton or neon has been determined. Two methods of heterogeneous cluster production were employed: co-expansion and doping/pick-up. By analyzing the line shapes, energy positions, and widths of the spectral cluster features the radial composition of the clusters produced by co-expansion were found to form close-to-equilibrium structures, placing the component with larger cohesive energy in the cluster core while the second component was to varying degree segregated toward the surface. By instead using the doping/pick-up technique the opposite radial structures, i.e. far-from-equilibrium structures, may be formed. In the case of argon/krypton clusters a similar surface structure is formed regardless of production technique. The second part of the Thesis concerns post-ionization decay processes. Experimental evidence for the Interatomic Coulombic Decay process, a theoretically predicted decay channel, is presented in a study of homogeneous neon clusters. The time scale of the decay was determined to 6±1 fs for bulk atoms and >30 fs for surface atoms in the neon cluster, showing the connection between local geometry and dynamics of the decay. Another channel for electronic relaxation is Auger decay. This Thesis presents a method of disentangling the spectral surface and bulk responses from clusters in Auger spectra. Studies of argon clusters show that the AES technique is more surface sensitive than XPS, even at the same electron kinetic energy. Furthermore, the effect scattering of the photoelectron has on the Auger spectra was investigated. Special effort was put into explaining an experimentally observed photon energy dependent intensity appearing on the high-kinetic energy side on the Auger signal. We propose that this intensity is due to a solid state-specific photoelectron recapture process we name Pre-Auger Recapture (PAR), which affects the kinetic energy of the Auger electrons.

Bayer processing of bauxite employed for production of alumina yield a residue red-mud. The worldwide annual-rate of red-mud generation is approximately 120 million tons, and most of this is stockpiled. Red mud is rich in elements like aluminum, titanium and rare earths, in addition to the major iron-bearing constituents. The objective of this research is to explore such a strategy to extract Iron as fine particulate magnetite. Pyrometallurgical reduction experiments using carbon mixtures and a novel hydrometallurgical route are experimented. Reduction experiments performed with petroleum coke as a reductant resulted in incomplete reduction. The ‘optimal conditionsÂ’ for gaseous state reduction are determined to be: a processing temperature of 540oC ± 10oC, partial pressures CO (g) and CO2 (g) each of 0.070atm (bar) ± 0.001atm.(bar)/ inert diluent-gas: N2 (g), for a conversion-time of 30min. A mathematical-model was developed on the basis of unidirectional-diffusion of CO2 (g) within the CO2 (g)–CO (g)–N2 (g) gas-phase of the porous product-layer. Magnetic separation applied to the optimally reduced sample in: obtaining a magnetic portion with high iron and non-magnetic portion containing nonferrous (Al, Ti) is not successful. This finding was subsequently attributed to the nanometer length-scales crystallites of the predominant iron-containing phase, hydrated ferric-oxide(s) as determined by STEM micrographs. In addition, the presence of substitution for Fe3+ by Al3+ and Ti3+/4+ are determined with the help of MÖssbauer spectrograms. A hydrometallurgical route involving selective leaching and precipitation of iron in red-mud is tried. Red-mud is leached in oxalic acid at: 95˚C, 15 % Pulp density, 2.5 h leaching time, 1.5 pH. Kinetic studies yielded the leaching mechanism to be predominantly fluid film control. Ferric oxalate in the leach liquor is reduced to insoluble ferrous oxalate selectively using Iron powder. The ferrous oxalate formed is ~98 % pure. The precipitated ferrous oxalate is magnetically separated and reduced in Nitrogen atmosphere to form fine particulate magnetite. Additionally an economic feasibility study was conducted for the hydro and pyro alternatives to produce magnetite using Monte Carlo Simulations by imparting uncertainties in various input cost components. A traditional process was also compared to the proposed approaches for Total Capital Investment (TCI), Total Product Cost (TPC), Net Present Value (NPV) and sensitivity analysis. ~52 % reduction in Total product cost, 46 % reduction in Total Capital Investment was achieved for the hydrometallurgical process when compared to the traditional approach.

L’objectif de cette thèse est de réaliser un agent de contraste vasculaire pour tomodensitométrie utilisable en préclinique. En collaboration avec le laboratoire de biogalénique de Strasbourg, ce travail a permis d’obtenir des nano-émulsions iodées produites par diffusion spontanée de surfactif et des nanoparticules iodées produites par ”émulsion - diffusion de solvant”, comme agent de contraste vasculaire. Ces émulsions et particules polymériques présentent en effet, un temps de rémanence vasculaire de plusieurs heures, un pouvoir contrastant suffisant pour un usage en tomodensitométrie (compris entre 170 et 400 HU), la possibilité de les administrer par intraveineuse et une stabilité de plusieurs mois. Les nano-émulsions, notamment celles produites à partir de Lipiodol®, sont les plus prometteuses comme agents de contraste vasculaire de par leur forte radiopacité (475 ± 30 HU) et leur rémanence vasculaire (T1/2 of 4.1 ± 1.10 h). Les nanoparticules iodées à base de PCL présentent un pouvoir contrastant inférieur (168 ± 13 HU) mais elles sont connus pour leur capacité à modifier la libération du principe actif encapsulé. De ce fait même si les agents de contraste de nature lipidique ou ceux inorganiques sont plus performant, elles restent intéressantes pour une visualisation rapide de la distribution du principe actif dans l’organisme. Cette thèse par ailleurs, apporte plusieurs éléments pour la compréhension de la formulation des nano-émulsions obtenues par diffusion spontanée de surfactif et celle des nanoparticules produites par ”émulsion - diffusion de solvant”. Concernant les nano-émulsions, l’influence de l’iodation des huiles et du surfactif a été étudiée autant sur le plan pharmacotechnique que ceux toxicologique et pharmacocinétique. Concernant les nanoparticules à base de PCL, nous avons montré que l’impact du type d’huile et de l’iodation, des polymères PCL et PCL-mPEG et de diverses méthodes de concentration sur la formulation / The aim of this thesis is to formulate a blood pool contrast agent for preclinical X-ray imaging application. In collaboration with the galenic laboratory of Strasbourg, this work has allowed to obtain iodinated nano-emulsions produced by spontaneous diffusion of surfactant and nano-particles produced by iodine ”emulsion - solvent diffusion” as blood pool contrast agent. These emulsions and polymer particles present indeed a vascular persistence of several hours, a sufficient contrast to be use in computed tomography (between 170 and 400 HU), the ability to be administered intravenous and stability of several months. Nano-emulsions, including those produced from Lipiodol®, are the most promising as blood pool contrast media by their high radiopacity (475 ± 30 HU) and vascular persistence (T1/2 of 4.1 ± 1.10 h). Iodinated nano-particles of PCL have a lower X-ray attenuation (168 ± 13 HU), but they are known for their control release of the encapsulated substances. Therefore even if inorganic or lipidic contrast agents show a better contrast, they remain attractive for rapid visualization of the co-encapsulated substance distribution in the body. This thesis also introduced several features for understanding the formulation of nano-emulsions obtained by spontaneous diffusion of surfactant and the nano-particles produced by ”emulsion - solvent diffusion.”

L’objectif de ce travail de thèse était de développer des encres organiques de polymères semi-conducteurs. Il s’est ainsi agi de synthétiser des latex de poly (3,4-éthylènedioxythiophène) (PEDOT) dispersibles en milieux organiques (cyclohexane ou toluène) par polymérisation oxydative de l’EDOT en présence de stabilisant stériques et/ou électrostatiques. Le stabilisant est un polymère fonctionnalisé par une unité ou plusieurs unités fonctionnelles qui peuvent réagir avec la chaîne de PEDOT en croissance assurant ainsi des liaisons covalentes ou électrostatiques entre celui-ci et le stabilisant. La taille des particules de PEDOT est contrôlée par la masse molaire, la concentration et par la fonctionnalité du stabilisant. Le PEDOT obtenu est caractérisé par diffusion de la lumière (DLS), par microscopie électronique à balayage (MEB) microscopie électronique à transmission (TEM) et par des mesures de conductivité. / Spherical poly(3,4-ethylenedioxythiophene) nano-particles with narrow size distribution were prepared in organic dispersant media in the presence of iron(III) chloride FeCl3 or iron(III) dodecylbenzenesulfonate {Fe(DBS)3} as oxidant and a functionalized polyisoprene (ω-R-PI) as a stabilizer. Two kinds of functionalized polyisoprene were used as stabilizers. Pyrrole, fluorene, Thiophene and methylthiophene end caped polyisoprenes were used as reactive stabilizers. Lithium sulfonate end caped polyisoprene was used as steric stabilizer. The effect of the nature of the solvent, the molar mass, the concentration, and the nature of the functional end unit of the stabilizer on the size and morphology of PEDOT particles were investigated. Polyisoprenes containing sulfonate groups were also used as steric/electrostatic stabilizers. By this way, the sulfonate groups act as counter ions for oxidized PEDOT leading to electrostatic attraction between it and the stabilizer, ensuring stabilization of the latex. Four kinds of polyisoprene-based steric electrostatic stabilizers having one or many sulfonate groups were prepared: sulfonate end-capped polyisoprene (PI-SO3Li), partially sulfonated polyisoprene (PIS), polyisoprene grafted to polystyrene sulfonate (PI-g-PSS) and polyisoprene grafted to polyisoprene sulfonate (PI-g-PIS). The effects of the molar mass of the stabilizer and the sulfonate group content on the PEDOT particle morphology were studied.PEDOT samples were characterized with transmission electron microscopy (TEM), atomic force microscopy (AFM), scanning electron microscopy (SEM), dynamic light scattering (DLS) analysis and conductivity measurements.

This work deals with preparation of PMMA based gel polymer electrolytes with high fire safety and high ionic conductivity. In the theoretical part of the work GPEs for Li – ion accumulators, fire safety tests, fire retardants are mentioned. Preparation of GPEs, electrical and other properties are described in the experimental part. Furthermore, new possible methods of gel preparation are discussed.

Addition of nano particles to cooling fluids has shown marked improvement in the heat transfer capabilities. Nanofluids, liquids that contain dispersed nanoparticles, are an emerging class of fluids that have great potential in many applications. There is a need to understand the fundamental behavior of nano dispersed particles with respect to their agglomeration characteristics and how it relates to the heat transfer capability. Such an understanding is important for the development and commercialization of nanofluids. In this work, the stability of nano particles was studied by measuring the zeta potential of colloidal particles, particle concentration and size. Two different sizes of silica nano particles, 10 nm and 20 nm are used in this investigation at 0.2 vol. % and 0.5 vol. % concentrations. The measurements were made in deionized (DI) water, buffer solutions at various pH, DI water plus HCl acid solution (acidic pH) and DI water plus NaOH solution (basic pH). The stability or instability of silica dispersions in these solutions was related to the zeta potential of colloidal particles and confirmed by particle sizing measurements and independently by TEM observations. Low zeta potentials resulted in agglomeration as expected and the measured particle size was greater. The heat transfer characteristics of stable or unstable silica dispersions using the above solutions were experimentally determined by measuring heat flux as a function of temperature differential between a nichrome wire and the surrounding fluid. These experiments allowed the determination of the critical heat flux (CHF), which was then related to the dispersion characteristics of the nanosilica in various fluids described above. The thickness of the diffuse layer on nano particles was computed and experimentally confirmed in selected conditions for which there was no agglomeration. As the thickness of the diffuse layer decreased due to the increase in salt content or the ionic content, the electrostatic force of repulsion cease to exist and Van der Waal's force of agglomeration prevailed causing the particles to agglomerate affecting the CHF. The 10nm size silica particle dispersions showed better heat transfer characteristics compared to 20nm dispersion. It was also observed that at low zeta potential values, where agglomeration prevailed in the dispersion, the silica nano particles had a tendency to deposit on the nickel chromium wire used in CHF experiments. The thickness of the deposition was measured and the results show that with a very high deposition, CHF is enhanced due to the porosity on the wire. The 10nm size silica particles show higher CHF compared to 20nm silica particles. In addition, for both 10nm and 20nm silica particles, 0.5 vol. % concentration yielded higher heat transfer compared to 0.2 vol. % concentration. It is believed that although CHF is significantly increased with nano silica containing fluids compared to pure fluids, formation of particle clusters in unstable slurries will lead to detrimental long time performance, compared to that with stable silica dispersions.

Solvent-free extrusion emulsification (SFEE) is a recently developed process for producing submicron particles with high viscosity polymers inside a twin-screw extruder without the use of hazardous solvents. Its dependency on a catastrophic phase inversion makes the process knowingly sensitive to a variety of formulation and operational variables, causing a narrow window of production. The purpose of this thesis was to investigate and improve process stability as well as widening operational window. Transient effects of the start-up procedure was investigated by considering the process stability and particle size distribution. The transient sensitivity corresponded to the residency of material in the dispersion zone. When a sub-optimal water/surfactant fraction was allowed to produce an undesired polymer-water (thick lamella) morphology, this morphology continued to persist until the critical first half of the dispersion zone was purged of existing mass. Lot to lot variability of polyester resin was used to investigate the sensitivities of the SFEE process more deeply to better understand the mechanism involved. In this case, acid number was shown to have a significant effect on the initial amount of water needed in the dispersion zone for phase inversion, resulting in an emulsification boundary dependent on the resin acid number. In fact, a significant correlation was found between the acidic end groups of the resin and the maximum amount of water content that could be used in the dispersion zone. The effect of feed rate, screw speed, dispersion length, and surfactant concentration were studied for their individual influence on widening the emulsification boundary. The most significant improvement was observed by applying a longer dispersion length or lower feed rate because both significantly increase the residence time. The effect of residence time on the emulsification boundary was attributed to the total strain imposed on the polymer/water mixture which was related to interfacial growth in the dispersion zone. / Dissertation / Doctor of Philosophy (PhD)