The continuous high demand on permanent magnets in industries opened new research plateau to develop alternative magnetic material. The current used permanent magnet materials in the market still suffer from high cost and insufficient magnetic or thermal properties. The central focus of this dissertation work is the optimization of cobalt carbide based nanomaterial by means of modifying polyol synthesis assisted by nucleation agent and systematic statistics using JMP software tool. In most existing literatures, producing cobalt carbide (Co2C or Co3C) lack reproducibility and consistency resulting in nonsolid magnetic properties results. The practical requirements for cobalt carbide to be used as permanent magnet are high coercivity (Hc), high magnetization (Ms), resulting in a high-energy product (HcxMs). Previous literatures have shown coercivities of 1.5 to 2.5 kOe for cobalt carbides under aggressive temperatures conditions (300oC) or after aligning the particles under magnetic field. A statistical guided method performed a sequence of experiments toward producing high coercivities using surface response design. Primarily, the statistical study to optimize cobalt carbide was made by analyzing experimental condition to fulfill high magnetic properties with tuned conditions as much as possible. Therefore, having the advantage for superior control on process variable when shifting cobalt carbide for scale up production in flow chemistry set up using microreaction system (MMRS). The optimization is based upon selecting the most important conditions in polyol reaction to produce cobalt carbide (Co2C or Co3C) and feed JMP software model e.g. reaction temperature, reaction time, and or precursor concentration…etc. These factors called (effects) used to design experiments and generate tables to run minimum experiments. Points of each effect (levels) are selected based on previous knowledge and experience with the synthesis. The output called (response) can be any of the magnetic properties of our interest e.g. magnetization (Ms), coercivity (Hc), or energy magnetic product (HcxMs). In the first model fit of cobalt carbide magnetic was studied in a polyol reaction to increase its magnetic energy product and optimize the experimental conditions. The results disclosed increase in magnetic energy product (6.2 MGOe) when validating the prediction model conditions suggested by JMP: shorter reaction time, and lower precursor concentration conditions at maximum reaction temperature. Finally, to my knowledge studying the effect of the nucleating agent to alter cobalt carbide growth have not been studied so far. Therefore, statistical study design using central composite design (CCD) to investigate the nucleating agent effect of silver nitrite on cobalt carbide coercivity was made. The importance of nucleating agent on coercivity is vigorous to attain and control the growth direction of cobalt carbide nanoparticles. This is due to the shape anisotropy contribution to enhance coercivity unlike weak shape anisotropy attributed to agglomeration of nanoparticles demonstrated in previous studies. Enhancement of coercivity reached 3 kOe with aspect ratio control as a function of silver nitrite concentration under lower reaction temperature. The continuous high demand on permanent magnets in industries opened new research plateau to develop alternative magnetic material. The current used permanent magnet materials in the market still suffer from high cost and insufficient magnetic or thermal properties. The central focus of this dissertation work is the optimization of cobalt carbide based nanomaterial by means of modifying polyol synthesis assisted by nucleation agent and systematic statistics using JMP software tool. In most existing literatures, producing cobalt carbide (Co2C or Co3C) lack reproducibility and consistency resulting in nonsolid magnetic properties results. The practical requirements for cobalt carbide to be used as permanent magnet are high coercivity (Hc), high magnetization (Ms), resulting in a high-energy product (HcxMs). Previous literatures have shown coercivities of 1.5 to 2.5 kOe for cobalt carbides under aggressive temperatures conditions (300oC) or after aligning the particles under magnetic field. A statistical guided method performed a sequence of experiments toward producing high coercivities using surface response design. Primarily, the statistical study to optimize cobalt carbide was made by analyzing experimental condition to fulfill high magnetic properties with tuned conditions as much as possible. Therefore, having the advantage for superior control on process variable when shifting cobalt carbide for scale up production in flow chemistry set up using microreaction system (MMRS). The optimization is based upon selecting the most important conditions in polyol reaction to produce cobalt carbide (Co2C or Co3C) and feed JMP software model e.g. reaction temperature, reaction time, and or precursor concentration…etc. These factors called (effects) used to design experiments and generate tables to run minimum experiments. Points of each effect (levels) are selected based on previous knowledge and experience with the synthesis. The output called (response) can be any of the magnetic properties of our interest e.g. magnetization (Ms), coercivity (Hc), or energy magnetic product (HcxMs). In the first model fit of cobalt carbide magnetic was studied in a polyol reaction to increase its magnetic energy product and optimize the experimental conditions. The results disclosed increase in magnetic energy product (6.2 MGOe) when validating the prediction model conditions suggested by JMP: shorter reaction time, and lower precursor concentration conditions at maximum reaction temperature. Finally, to my knowledge studying the effect of the nucleating agent to alter cobalt carbide growth have not been studied so far. Therefore, statistical study design using central composite design (CCD) to investigate the nucleating agent effect of silver nitrite on cobalt carbide coercivity was made. The importance of nucleating agent on coercivity is vigorous to attain and control the growth direction of cobalt carbide nanoparticles. This is due to the shape anisotropy contribution to enhance coercivity unlike weak shape anisotropy attributed to agglomeration of nanoparticles demonstrated in previous studies. Enhancement of coercivity reached 3 kOe with aspect ratio control as a function of silver nitrite concentration under lower reaction temperature.

<p>Diabetes-induced renal complications, i.e. diabetes nephropathy, are a major cause of morbidity and mortality. The exact mechanism mediating the negative influence of hyperglycaemia on renal function is unclear, although several hypotheses have been postulated. Glucose-induced excessive formation of reactive oxygen species (ROS) and increased glucose flux through the polyol pathway are two major mechanisms that have recently gained increasing support. In order to investigate the development of hyperglycaemia-induced renal alterations further, it is of great importance to use an animal model in agreement with the pathological development in diabetic patients.</p><p>The aims of these investigations were to evaluate the streptozotocin (STZ)-diabetic Wistar Furth rat as a model for human diabetic nephropathy and to investigate involvement of ROS and the polyol pathway in development of diabetes-induced renal alterations.</p><p>The used STZ-diabetic animal model displayed several similarities with the progression of human disease, including initial hyperfiltration and albuminuria. However, the observed proteinuria could be partly linked to the STZ treatment <i>per se</i>, making the use of this animal model less suitable for research concerning diabetes-induced urinary protein leakage.</p><p>The diabetic state induced numerous alterations in renal function and metabolism, including increased oxygen consumption, decreased renal oxygen tension (pO₂), and altered lactate/pyruvate ratio. These renal alterations were preventable by daily treatment with either a radical scavenger (α-tocopherol) or an aldose reductase inhibitor (AL-1576).</p><p>In separate experiments the influence of nitric oxide (NO) on renal blood perfusion and pO₂ was investigated. The diabetic animals displayed a larger increase in renal NO activity after injecting the NO substrate L-arginine compared to non-diabetic animals, suggesting substrate limitation of the nitric oxide synthase during chronic hyperglycaemia.</p><p>In conclusion, the results from these investigations show that both ROS and the polyol pathway are involved in the development of diabetes-induced renal alterations in the STZ- diabetic Wistar Furth rat.</p>

Diabetes-induced renal complications, i.e. diabetes nephropathy, are a major cause of morbidity and mortality. The exact mechanism mediating the negative influence of hyperglycaemia on renal function is unclear, although several hypotheses have been postulated. Glucose-induced excessive formation of reactive oxygen species (ROS) and increased glucose flux through the polyol pathway are two major mechanisms that have recently gained increasing support. In order to investigate the development of hyperglycaemia-induced renal alterations further, it is of great importance to use an animal model in agreement with the pathological development in diabetic patients. The aims of these investigations were to evaluate the streptozotocin (STZ)-diabetic Wistar Furth rat as a model for human diabetic nephropathy and to investigate involvement of ROS and the polyol pathway in development of diabetes-induced renal alterations. The used STZ-diabetic animal model displayed several similarities with the progression of human disease, including initial hyperfiltration and albuminuria. However, the observed proteinuria could be partly linked to the STZ treatment per se, making the use of this animal model less suitable for research concerning diabetes-induced urinary protein leakage. The diabetic state induced numerous alterations in renal function and metabolism, including increased oxygen consumption, decreased renal oxygen tension (pO2), and altered lactate/pyruvate ratio. These renal alterations were preventable by daily treatment with either a radical scavenger (α-tocopherol) or an aldose reductase inhibitor (AL-1576). In separate experiments the influence of nitric oxide (NO) on renal blood perfusion and pO2 was investigated. The diabetic animals displayed a larger increase in renal NO activity after injecting the NO substrate L-arginine compared to non-diabetic animals, suggesting substrate limitation of the nitric oxide synthase during chronic hyperglycaemia. In conclusion, the results from these investigations show that both ROS and the polyol pathway are involved in the development of diabetes-induced renal alterations in the STZ- diabetic Wistar Furth rat.

La demande en composés chiraux est en plein essor ces dernières années. Pour accéder à leur synthèse, la biocatalyse, couplée à l'irradiation pourrait être une méthode innovante. Il existe en effet de nombreux cas dans la littérature où l'utilisation de micro-onde semble avoir un effet activateur sur l'efficacité enzymatique.Cependant, l'effet de l'irradiation micro-onde est mal compris et controversé. Le but de cette thèse était d'étudier l'impact de l'irradiation micro-onde sur des lipases, immobilisées ou non, en étudiant différentes réactions modèles, allant de la résolution d'alcools secondaires linéaires simples à la résolution de polyols complexes, et alcools polyfonctionalisés, par comparaison entre chauffage sous irradiation micro-onde (en conditions drastiques ou non) au chauffage classique. L'étude de l'irradiation micro-onde sur la stabilité enzymatique et sur paramètres intrinsèques de l'enzyme après modification des paramètres réactionnels a permis de mettre en évidence un rôle indéniable de l'irradiation micro-onde sur l'efficacité des réactions enzymatiques. Il a été possible d'une part de diminuer de façon importante les temps réactionnels, comparé au chauffage traditionnel,et d'autre part de contrôler efficacement l'énantio préférence et la sélectivité de la lipase pour l'obtention de molécules d'intérêt. Par des procédés innovants, l'impact de la puissance d'irradiation a été montré comme hautement dépendant du modèle réactionnel étudié. En optimisant les conditions réactionnelles pour obtenir les meilleures sélectivités et activités enzymatique sous irradiation micro-onde, la synthèse de a-hydroxyamides chiraux et de polyols parfaitement résolus a pu être entreprise de façon rapide, propre, tout en respectant les principes de chimie verte.

Conscients de la raréfaction progressive et l'augmentation continue du coût du pétrole et aussi des volumes importants des tensioactifs produits et éliminés chaque année, l'industrie chimique s'intéresse de plus en plus aux ressources issues de la biomasse. Cependant, dans le marché européen des tensioactifs, la part des produits d'origine végétale par rapport aux dérivés pétrochimiques est estimée à seulement 20%. Compte-tenu de ces enjeux, de nouvelles stratégies de synthèse pour produire des tensioactifs ayant des structures originales issus d'agro-ressources sont nécessaires. Dans le cadre d'une collaboration de recherche, l'ITERG (Pessac) et l'ICBMS (équipe COB-INSA) de Lyon se sont associées pour développer la synthèse de nouveaux glycolipides amphiphiles obtenus par fonctionnalisation d'huiles végétales époxydées. Les enjeux synthétiques ont concerné la compétition entre les deux fonctions réactives des huiles époxydées (ester et époxyde) et la multifonctionnalité des sucres et autres polyols utilisés comme substrats nucléophiles. Plusieurs séries de composés originaux ont été préparées, et leurs propriétés physico-chimiques ont été évaluées en regard des applications industrielles visées. Parmi les produits synthétisés, quelques uns ont également été évalués en tant que monomères biosourcés.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-06-21T12:08:58Z No. of bitstreams: 2 Tese - Leonardo Martins de Abreu - 2017.pdf: 3441219 bytes, checksum: 28d75017e1ff1cdccf27de35d71771ea (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-07-10T13:08:28Z (GMT) No. of bitstreams: 2 Tese - Leonardo Martins de Abreu - 2017.pdf: 3441219 bytes, checksum: 28d75017e1ff1cdccf27de35d71771ea (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-07-10T13:08:28Z (GMT). No. of bitstreams: 2 Tese - Leonardo Martins de Abreu - 2017.pdf: 3441219 bytes, checksum: 28d75017e1ff1cdccf27de35d71771ea (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-05-12 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Using continuum and discrete solvent description models, we have investigated the chain length dependence of hydration free energy of polyol, glycine and ANK peptides. In this work this property values were calculated using thermodynamics integration with classical molecular dynamics simulation of one solute molecule to around 1000 solvent molecules. In addition, hydration free energy of polyol, glycine and ANK peptides were also calculated using polarizable continuum model in combination with the universal solvation model. Dipole moment and linear polarizability of the three systems had been also calculate using the PCM method. Our MD results show that ΔG exhibit a linear pattern with the size of glycine and ANK chain as well as observed for organic compounds in literature. In opposition, polyol’s ΔG shows a nonlinear behavior with increasing chain length and for this group of molecules it were found that water solvating effects have an important role over the polyol’s electric properties. These results suggest that in the case of polyols not only variation of polarizability but also variations of dipole moment in going from vacuum to water can influence the behavior of the free energy of hydration. All DM and PCM calculations were performed using the GROMACS 4.5 and the GAUSSIAN09 programs, respectively. / Utilizando modelos contínuo e discreto de descrição de solventes investigamos o comportamento da variação da energia livre na hidratação de series homólogas de poliol, glicina e peptídeos ANK. Neste trabalho os valores da energia de hidratação foram obtidos por integração termodinâmica utilizando simulações de dinâmica molecular clássica em sistemas com uma molécula de soluto para aproximadamente 1000 moléculas de solvente. Adicionalmente, o s resultados de ΔG foram obtidos utilizando o modelo contínuo polarizável combinado com o modelo de solvatação universal. Com o modelo PCM estudamos ainda o momento de dipolo e a polarizabilidade linear destes sistemas em questão e analisamos as contribuições que estas propriedades tem sobre a energia livre de hidratação e sua evolução com o crescimento de sistemas. Os resultados obtidos mostram que a variação da energia livre em função do número de resíduos cresce em valor absoluto para os três sistemas estudados. Para as moléculas de glicina e de peptídeos ANK observa-se um comportamento linear de ΔG com o número N de subunidades do sistema, semelhante ao observado para sistemas moleculares apresentados na literatura. Diferentemente, para as moléculas de poliol, os resultamos de ΔG exibem um comportamento não linear com o crescimento do sistema. Para esse grupo de moléculas inclusão do solvente tem grande impacto sobre o momento de dipolo e sobre a polarizabilidade linear. Este resultado mostra que para as moléculas de poliol não apenas a polarizabilidade, mas também variações no momento de dipolo podem influenciar o comportamento da energia livre de hidratação. Todos os cálculos foram realizados utilizando o programa GROMACS 4.5.4 e GAUSSIAN09.

Les composés de la famille LAMOX, dérivés de La2Mo2O9, présentent une conductivité ionique élevée mais peuvent être conducteurs mixtes s'ils sont réduits sous atmosphère pauvre en oxygène. Dans ce travail, de nouvelles méthodes de synthèse de La2Mo2O9 par chimie douce (la voie sol gel et le procédé polyol) sont optimisées pour faciliter la mise en forme selon l’application souhaitée.Concernant les synthèses réalisées par voie sol gel, le composé La2Mo2O9 pur a été obtenu à partir de l’acétate de lanthane et du molybdate d’ammonium ou du chlorure de molybdène. L’influence de plusieurs paramètres de synthèse a été déterminée. L’ajout de deux tensioactifs a été testé : le bromure de diméthyldioctadécyl-ammonium (DDAB) et le F127. Les poudres finales sont quasi-pures après un traitement thermique à 950°C pendant 2 heures, ce qui ne permet pas d’avoir des surfaces spécifiques élevées.Dans le cas du procédé polyol, nous avons obtenu La2Mo2O9 pur sous forme de roses des sables par agglomération de plaquettes polycrystallines très fines constituées de cristallites de quelques dizaines de nanomètres, après un traitement thermique à plus basse température de l’ordre de 550°C. L’effet de plusieurs paramètres sur la morphologie et la pureté des poudres a été testé. En particulier, des particules sphériques agglomérées ont été obtenues en utilisant l’éthylèneglycol comme solvant en présence d’urée. L’ajout du tensioactif bromure de diméthyl-dioctadécyl-ammonium (DDAB) permet de doubler la surface spécifique par rapport aux échantillons sans tensioactif, celle ci passant de 16 à 30 m2.g-1. Finalement, de tous premiers essais ont été réalisés pour tenter d’obtenir des films minces par centrifugation.Les mesures de conductivité ont été enregistrées sur des pastilles à porosité fermée (densité relative supérieure à 92%) sans avoir recours à une étape de broyage. Les mesures de conductivité montrent que, selon les paramètres de synthèse, la conductivité de grain peut être légèrement accrue.L’étude de la réductibilité, sous H2 dilué, des poudres issues de la synthèse par voie polyol, montre que les pertes en oxygène sont plus rapides et plus importantes que pour des poudres synthétisées par voie solide. La ré-oxydation des poudres amorphes est également plus rapide et se produit à bien plus basse température dans le cas des poudres obtenues par la voie polyol. / La2Mo2O9 based oxides (LAMOX) exhibit high ionic conductivity but can be mixed conductors if they are reduced under low-oxygen atmosphere. In this work, new synthesis methods of La2Mo2O9 by soft chemistry (sol gel route and polyol process) are optimized to facilitate the sample shaping depending on the desired application.Concerning the sol gel syntheses, pure La2Mo2O9 compound was obtained from lanthanum acetate and ammonium molybdate or molybdenum chloride. The influence of several synthesis parameters was determined. The addition of two surfactants was tested: dimethyl dioctadecyl ammonium bromide (DDAB) and F127. The final powders are almost pure after heat treatment at 950 °C for 2 hours, which prevents from high specific surface areas.In the case of the polyol process, pure La2Mo2O9 was obtained as desert roses by agglomeration of very fine polycrystalline platelets built from crystallites of a few tens of nanometers size, after a heat treatment at a lower temperature of about 550°C. The effect of various parameters on the morphology and purity of the powder was tested. In particular, agglomerated spherical particles have been obtained using ethylene glycol as solvent in the presence of urea. The addition of DDAB surfactant enables a doubling the specific surface area comparatively to samples without surfactant, from 16 to 30 m2.g-1. Finally, first tests were carried out as attempts to obtain thin films by centrifugation.Conductivity measurements were recorded on pellets presenting closed porosity (relative density greater than 92%), obtained without the help of a milling step. Conductivity measurements showed that, depending on the synthesis parameters, the grain conductivity can be slightly increased.The study of the reducibility, under diluted H2, of powders resulting from the synthesis by the polyol process, shows that the oxygen losses are faster and larger than with powders synthesized by solid state reaction. Reoxidation of amorphous powders is also faster and occurs at much lower temperature in the case of powders obtained by the polyol pathway.

No description available.

The work of this dissertation is centered on two non-conventional synthetic approaches to ferromagnetic nanomaterials: high-throughput experimentation (HTE) (polyol process) and continuous flow (CF) synthesis (aqueous reduction and the polyol process). HTE was performed to investigate phase control between FexCo1-x and Co3-xFexOy. Exploration of synthesis limitations based on magnetic properties was achieved by reproducing Ms=210 emu/g. Morphological control of FexCo1-x alloy was achieved by formation of linear chains using an Hext. The final study of the FexCo1-x chains used DoE to determine factors to control FexCo1-x, diameter, crystallite size and morphology. [Ag] with [Metal] provide statistically significant control of crystallite size. [OH]/[Metal] predict 100 % FexCo1-x at > 30. To conclude section 1, a morphological study was performed on synthesis of Co3-xFexOy using the polyol process. Co3-xFexOy micropillars were synthesized at various sizes. The close proximity of the particles in the nanostructure produced an optical anisotropy and was magnetically induced which is evidence for the magneto-birefringence effect. The second non-conventional synthetic approach involves continuous flow (CF) chemistry. Co nanoparticles (Ms=125 emu/g) were newly synthesized by aqueous reduction in a microreactor and had 30 ±10 nm diameter and were produced at >1g/hr, a marker of industrial-scale up viability. The final work was the CF synthesis of FexCo1-x. The FexCo1-x was synthesized with limitation to the composition. The maximum FexCo1-x phase composition at 20 % resulted from the aqueous carrier solvent triggering oxide formation over FexCo1-x.

Recentemente, nanopartículas (NP) de FePt de fase tetragonal de face centrada (fct) em sistemas auto-organizados tem sido sintetizados como potenciais candidatos para gravação magnética de ultra-alta densidade (UHMR), devido a sua elevada anisotropia magnetocristalina. Entretanto, o alinhamento magnético de NP esféricas tem sido constantemente um problema, pois os eixos de fácil magnetização das NP permanecem randomicamente orientados nas três direções. Na tentativa de superar os problemas decorrentes da falta de alinhamento magnético, trabalhos recentes sugerem que NP alongadas em sistemas auto-organizados orientados perpendicularmente a superfície do substrato como possível solução para a textura e alinhamento magnético. Até o presente momento, as sínteses de nanobastões (NB) e de nanofios (NF) de FePt reportadas na literatura levam a obtenção de NP na fase cúbica de face centrada (fcc), a qual possui baixa anisotropia magnetocristalina e se mostrou termicamente instável, resultando em NP esferoidais após o processo de recozimento para a transformação da fase fcc para fct. Neste trabalho, NP de Fe55Pt55 com tamanho e composição química controlada e morfologia de nanofios e nanobastões foram sintetizadas através da adequação do método do poliol modificado. Além disso, as condições de sínteses foram ajustadas para a obtenção direta das NP na fase fct. Sistemas auto-organizados de NB orientados longitudinalmente ou perpendicularmente em arranjos hexagonais compactos foram obtidos utilizando, respectivamente, ácido oléico (AO) e oleilamina (Oam) ou hexadecilamina (HDA) como agentes espaçadores. Sistemas de NB orientados perpendicularmente com alinhamento magnético devido à anisotropia de forma combinado com as propriedades magnéticas resultantes da fase parcialmente tetragonal obtida sugerem um forte candidato a aplicação em UHMR com densidade de gravação magnética na ordem de terabits/pol2. / Recently, self-assembled FePt nanoparticles (NP) in face-centered tetragonal phase (fct) has been synthesizes as potential candidates for Ultra-High Magnetic Recording Systems (UHMR) due to high magnetocrystalline anisotropy. However, the magnetic alignment of these self-assembled fct-FePt nanoparticles also has been a constant limiting factor, since the axes of easy magnetization of spherical nanoparticles are presented randomly oriented in three directions. Concerning to avoid these restrictions arising from magnetic alignment, one-dimensional NP perpendicularly oriented on the magnetic medium surface has been reported as a possible solution for texture and magnetic alignment. To date, the reported nanorods (NR) and nanowires (NW) synthesized in the literature showed face centered cubic phase (fcc) which present poor magnetocrystalline anisotropy, instead the fct desirable phase, and were found to be thermally unstable resulting in spheroidal NP after annealing required to phase transformation from fcc to fct. In this work, Fe55Pt45 NP with morphologies varying from nanospheres, NR with different lengths up to NW were synthesized by a modified polyol process. Furthermore, the synthesis conditions were adjusted to obtain FePt NP directly in fct phase. Either longitudinal or perpendicular self-assembled NR systems in a hexagonal compact array were obtained using oleic acid (OA) and oleylamine (Oam) or hexadecylamine (HAD), respectively, as molecular organic spacers. Perpendicularly oriented NR system led to magnetic alignment due to shape anisotropy and combined with the magnetic properties due to partial tetragonal phase suggest a strong future candidate to ultra-high magnetic density recording applications capable to achieve density of Terabits/in2.