Дисертації з теми "Bio hydrogène"
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1
Papadakis, Michail. "Bio-inspired production of dihydrogen." Electronic Thesis or Diss., Aix-Marseille, 2023. http://www.theses.fr/2023AIXM0061.
Повний текст джерелаАнотація:
Dans ce travail, nous avons synthétisé, caractérisé et testé différentes séries de complexes de nickel basés sur des ligands thiocarbazone pour leur capacité à produire de l’hydrogène à partir de deux processus catalytiques différents. La première partie de ce travail de thèse décrit l'utilisation de deux nouvelles familles basées sur des ligands bis-thiosemicarbazone et étudie comment une modulation appropriée du ligand peut affecter les performances électrocatalytiques pour la production d’hydrogène. La deuxième partie décrit l'utilisation d'un complexe de nickel polynucléaire et comment l'incorporation de plusieurs centres métalliques peut affecter l'activité électrocatalitique du système. Dans la dernière partie du manuscrit, de nouveaux systèmes photocatalytiques ont été développés en utilisant des nanoparticules de carbone comme capteurs de lumière et la série de complexes nickel à ligands thiosemicarbazones comme centres catalytiques pour photoproduire de l’hydrogèneIn this work, we have synthesized, characterized and tested different series of nickel complexes based on thiocarbazone ligands for their ability to produce hydrogen from two different catalytic processes. The first part of this Ph.D. work describes the use of two new families based on bis-thiosemicarbazone ligands and investigates how appropriate ligand-tailoring can affect electrocatalytic performance for HER. The second part describes the use of a polynuclear nickel complex and how the incorporation of several metallic centers can affect electrocatalysis. In the last part of the manuscript, new photocatalytic systems were developed using carbon nanodots as light harvesters and the series of nickel-thiosemicarbazone complexes as catalytic centers for photo-producing hydrogen
2
Kamara, Konakpo Parfait. "Stratégies d’utilisation du bio hydrogène pour la technologie PEMFC : utilisation directe." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALI037.
Повний текст джерелаАнотація:
La France dans le but de décarboner son mix énergétique et baisser ses émissions de CO2 a décidé d’investir massivement dans la production décarbonée d’hydrogène comme vecteur d’énergie pour des applications de mobilités ou stationnaires[1]. Sur le million de tonnes d’hydrogène produit en France, 96 % est produit par vaporeformage d’hydrocarbures. La stratégie Française vise à développer la filière hydrogène en investissant dans l’installation d’électrolyseurs. De plus les dernières découvertes d’énormes gisements d’hydrogène naturel (46 millions de tonnes d’hydrogène en Lorraine) crée l’enthousiasme et agrandi le champ des perspectives. [2]. Une autre filière de production d’hydrogène décarboné dont on parle le moins est la filière biologique qui présente un grand potentiel de diversifications des voies de productions. L’hydrogène issu de ces filières pose le problème de sa qualité pour une application dans la mobilité ou le stationnaire dans des systèmes de pile à combustible.L’objet de ces travaux de thèse est de définir des stratégies pour l’utilisation du bio hydrogène ou hydrogène naturel par la technologie de pile à combustible à membrane échangeuse de protons (PEMFC) et en passant par les étapes de production de l’hydrogène jusqu’à sa conversion électrochimique.La première partie a consisté à étudier l’impact des impuretés ou diluants (N2, Ar, He, CH4, CO2) contenus dans l’hydrogène issu des filières biologique et natif dans une demi-cellule (cellule de diffusion de gaz, GDE). Ensuite cette étude a été étendue à une mono cellule de pile à combustible à membrane échangeuse de protons. Enfin un réacteur biologique à échelle du laboratoire a permis de produire de l’hydrogène à partir de sources organiques par photo fermentation (PF) qui a ensuite été testé en GDE. Plusieurs techniques de caractérisations électrochimiques et physicochimiques comme la voltammétrie cyclique, la chrono amperommétrie, la mesure de surface électro-active par CO stripping, la microscopie électronique à balayage et à transmission, la chromatographie ionique etc…ont permis d’évaluer les performances de la PEMFC alimenté par du bio hydrogène ainsi que son impact sur les éléments d’une pile à combustible.Les résultats de l’activité des électrodes pour la réaction d’oxydation de l’hydrogène en GDE ont mis évidence des effets de limitations par le transport de matières pour l’ensemble mélange, avec des comportements particuliers observés pour le mélange à l’azote, et les mélanges au méthane et au dioxyde de carbone qui en plus de la dilution ont un effet d’empoisonnement au monoxyde de carbone de l’électrode.Ensuite, les tests en mono cellule alimenté par les mélanges H2/Ar, H2/N2 et H2/CO2 à 30 et 40 % volumique en H2 pour une application stationnaire ont révélé des pertes de performances plus importantes pour le mélange au dioxyde carbone, les mélanges à l’argon et à l’azote ont des performances quasiment équivalentes. Ces pertes de performances sont dues à des pertes de surfaces électro actives.Enfin la production de bio hydrogène par PF a montré que le choix de la biomasse, le prétraitement et la souche bactérienne influençaient la qualité du biogaz produit et les performances électrochimiques obtenues à partir de ce dernier sans étapes de purification.Références[1] « Présentation de la stratégie nationale pour le développement de l’hydrogène décarboné en France ». Consulté le: 11 janvier 2024. [En ligne]. Disponible sur: https://www.economie.gouv.fr/presentation-strategie-nationale-developpement-hydrogene-decarbone-france[2] « Le plus gros gisement d’hydrogène naturel du monde vient d’être découvert en France », SudOuest.fr. Consulté le: 11 janvier 2024. [En ligne]. Disponible sur: https://www.sudouest.fr/economie/energie/le-plus-gros-gisement-d-hydrogene-naturel-du-monde-vient-d-etre-decouvert-en-france-17826239.phpWith the aim of decarbonizing its energy mix and lowering its CO2 emissions, France has decided to invest massively in the decarbonized production of hydrogen as an energy carrier for mobility and stationary applications [1]. Of the one million ton of hydrogen produced in France, 96% is produced by steam reforming of hydrocarbons. France's strategy is to develop the hydrogen sector by investing in the installation of electrolyzers. What's more, the latest discoveries of huge deposits of natural hydrogen (46 million tons of hydrogen in Lorraine) are creating enthusiasm and expanding the field of prospects. [2]. Another decarbonated hydrogen production sector that is less talked about is the biological sector, which offers great potential for diversifying production routes. Hydrogen from these sources raises the question of its quality for use in mobility or stationary fuel cell systems.The aim of this thesis is to define strategies for the use of bio-hydrogen or natural hydrogen using proton exchange membrane fuel cell (PEMFC) technology, from hydrogen production to electrochemical conversion.The first part consisted in studying the impact of impurities or diluents (N2, Ar, He, CH4, CO2) contained in hydrogen from biological and native processes in a half-cell (gas diffusion electrode, GDE). This study was then extended to a single-cell proton exchange membrane fuel cell. Finally, a laboratory-scale biological reactor was used to produce hydrogen from organic sources by photo fermentation (PF), which was then tested in a GDE. Several electrochemical and physicochemical characterization techniques, such as cyclic voltammetry, chrono amperometry, CO stripping for electroactive surface measurement, scanning and transmission electron microscopy, ion chromatography, etc., were used to assess the performance of the PEMFC fed by bio-hydrogen, and its impact on fuel cell components.The results of the electrode activity for the hydrogen oxidation reaction in GDE revealed mass-transport limitation effects for the mixtures, with a particular behavior observed for the nitrogen mixture, and the methane and carbon dioxide mixtures, which in addition to dilution have a carbon monoxide poisoning effect on the electrode.Next, single-cell tests using H2/Ar, H2/N2 and H2/CO2 mixtures at 30 and 40% H2 by volume for stationary applications revealed greater performance losses for the carbon dioxide mixture, while the argon and nitrogen mixtures performed almost equally well. These performance losses are due to electroactive surface losses.Finally, the production of biohydrogen by PF showed that the choice of biomass, pre-treatment and bacterial strain influenced the quality of the biogas produced and the electrochemical performances obtained from it without purification steps.References[1] « Présentation de la stratégie nationale pour le développement de l’hydrogène décarboné en France ». Consulté le: 11 janvier 2024. [En ligne]. Disponible sur: https://www.economie.gouv.fr/presentation-strategie-nationale-developpement-hydrogene-decarbone-france[2] « Le plus gros gisement d’hydrogène naturel du monde vient d’être découvert en France », SudOuest.fr. Consulté le: 11 janvier 2024. [En ligne]. Disponible sur: https://www.sudouest.fr/economie/energie/le-plus-gros-gisement-d-hydrogene-naturel-du-monde-vient-d-etre-decouvert-en-france-17826239.php
3
Hartunians, Jordan. "High temperature H2 bio-production in Thermococcales models : setting up bases optimized high pressure solutions." Thesis, Brest, 2020. http://www.theses.fr/2020BRES0033.
Повний текст джерелаАнотація:
L’H2, vecteur d’énergie prometteur, peut être synthétisé par les Thermococcales. La haute pression (HP) influencerait le métabolisme associé, mais n’a pas été envisagée en pratique. Après criblage d’isolats pour dégradations de substrats et productions d’H2, T. barophilus MPT, croissant préférentiellement à 40 MPa, a été choisi comme modèle, et sa fermentation a été décrite dans un contexte appliqué. Des méthodes HP ont été optimisées pour étudier l’H2. Un bioréacteur de 400mL de culture continue a été amélioré, maintenant des fluides corrosifs à HP hydrostatique (jusqu’à 120 MPa) et gazeuse (jusqu’à 40 MPa) jusqu’à 150 °C. Il a permis de mesurer la production d’H2 de notre souche à HP gazeuse. Un tube compressible pour culture discontinue à phase gaz étanche a été inventé, et a servi à mesurer la production d’H2 de T. barophilus en HP hydrostatique. Le métabolisme HP de la souche a été étudié grâce à des délétions préalables de gènes clés (mbh, mbs, co-mbh, shI, shII). Les rôles des enzymes liées ont été précisés via des mesures de croissances, produits (H2, H2S, acétate) et expressions génétiques des mutants, à 0,1 et 40 MPa. La tolérance à l’H2 de T. barophilus a été augmentée par évolution adaptative en laboratoire.« Evol », la souche fille acclimatée durant 76 générations à une saturation d’H2, a crû dans 10% d’H2, contrairement à la souche mère. Pour comprendre ces adaptations, les produits (H2, H2S, acétate), transcriptomes et génomes des deux souches ont été comparés. Avec 119 mutations génomiques, le métabolisme de l’H2 a été modifié dans le variant. Ce projet souligne l’intérêt du caractère piézophile des Thermococcales dans la bio-production d’H2 et permet de proposer des stratégies d’H2 et permet de proposer des stratégies d’optimisationH2, a promising energetic vector, can be synthesized by Thermococcales. High pressure (HP) could influence the associated metabolism, but was not practically considered. After having screened isolates for assets in substrate degradation and H2 yields, T. barophilus MPT, growing optimally at 40 MPa, was chosen as a model and its metabolism was characterized in an applied context. Methods for HP culture were optimized for H2 studies. Our HP bioreactor for continuous culture underwent major improvements. This 400 mL container, able to maintain corrosive fluids at hydrostatic (up to 120 MPa) and gas (up to 40 MPa) pressures, at up to 150 °C, served to assess H2 production of our strain at high gas pressure. We also created a compressible device for discontinuous leak-free gas-phase incubations, allowing to measure T. barophilus HP H2 production (hydrostatic). HP adaptations of T. barophilus were observed thanks to previous deletions of key genes (mbh, mbs, co-mbh, shI, shII).We refined the roles of each concerned enzyme by assessing growths, end-products (H2, H2S, acetate), and gene expressions of the mutants, at 0.1 and 40 MPa. Additionally, we enhanced H2 tolerance in our model by adaptive laboratory evolution. “Evol”, the ensuing strain acclimatized to H2-saturating conditions for 76 generations, grew in 10% H2, contrarily to the parent strain. To understand such adaptation, we compared both strains’ end-products (H2, H2S, acetate), transcriptomes, and genomes.119 mutations were detected and the H2 metabolism was changed in the new variant. This work underlines the interest of Thermococcales’ piezophily for H2 bio-production and permits to propose optimization strategies
4
Busselez, Rémi. "Propriétés de fluides vitrifiables bio protecteurs nanoconfinés." Rennes 1, 2008. http://www.theses.fr/2008REN1S057.
Повний текст джерелаАнотація:
Il a été prouvé que le confinement à des échelles nanométriques de liquides moléculaires simples modifie considérablement leur structure et leurs propriétés dynamiques et thermophysiques. Un nombre important d'études consacrées aux liquides moléculaires formateurs de verres dans des géométries confinées ont permis de mettre en évidence des effets complexes conjugués de basse dimmensionnalité, de taille finie et de surface. La compréhension de la dynamique des liquides simples à l'interface ou confinés doit être étendue à des liquides plus complexes intéréssants différents secteurs technologiques et biologiques. Un de ces secteurs est la bioprotection. Cependant, un niveau supérieur de complexité est attendu dans les fluides bioprotecteurs confinés, qui sont des mélanges de liquides moléculaires vitrifiables formant des liaisons hydrogènes fortes et sélectives. Nous avons réalisé une étude structurale et dynamique de la solution bioprotectrice de réference glycérol-tréhalose confinée dans des nanopores unidirectionnels de silicium. Des expériences de RMN du solide et de diffusion de neutrons ont été combinées avec des simulations de dynamique moléculaire. Elles révèlent des effets antagonistes entre la concentration en tréhalose et le nanoconfinement sur la structure et la dynamique rapide (nanoseconde) et vitreuseIt was shown that confinement on a nanometric scale considerably modifies the structure, the thermodynamical and dynamical properties of simple molecular liquids. A large number of studies devoted to pure molecular glass formers in restricted geometries have revealed a complex entanglement of low dimensionality, finite size and surface effects. The current understanding of the dynamics of interfacial or confined liquids must be extended to more complex fluids, in order to be relevant to different domains of technological or biological interest. One of these concerns biopreservation. Indeed, a new level of complexity is awaited for confined bioprotectant solutions, which are multi-component systems with strong and selective H-bond interactions. We have performed a structural and dynamical investigation of the archetype glycerol-trehalose bioprotectant solution confined in silicon unidirectional nanopores. Neutron scattering and solid state NMR experiments have been combined to molecular dynamic simulations. They unambiguously reveal antagonist effects of trehalose concentration and nanoconfinement on the structure and molecular dynamics from the nanosecond time scale to the glassy arrest
5
Metayé, Romain. "Vers une photoproduction de l'hydrogène par des catalyseurs immobilisés bio-inspirés." Palaiseau, Ecole polytechnique, 2010. http://www.theses.fr/2010EPXX0074.
Повний текст джерела
6
Sahyouni, Farah Al. "Impact Thermo-Hydro-Bio-Chemio-Mécanique du stockage géologique souterrain de H₂." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0297.
Повний текст джерелаАнотація:
L'hydrogène issu de l'électrolyse de l'eau est considéré au stockage géologique à grande échelle pour combler l'intermittence des énergies renouvelables. Il peut être stocké soit dans des cavernes saline, soit dans des roches poreuses (les aquifères salins et les réservoirs de pétrole et de gaz épuisés). Cette thèse propose une évaluation du risque de fuite de gaz dans le cas de cavités salines et du risque d'altération biogéochimique du stock dans le cas de roches réservoirs poreuses. Le sel est un matériau polycristallin à très faible perméabilité intrinsèque dans les zones non perturbées (environ 10-21 m2). Sa capacité d'étanchéité est due aux spécificités du comportement mécanique du sel et de l'écoulement du gaz dans de tels réservoirs non conventionnels (effet Klinkenberg). Le chargement déviatorique sous faible confinement (1MPa) induit une augmentation de la perméabilité aux gaz à partir du seuil de dilatance due à la microfissuration. Ainsi, comprendre la relation complexe entre l'évolution de la perméabilité et les sollicitations mécaniques et thermiques est important pour comprendre tout risque de fuite. Ainsi, nous avons réalisé une série d'expérience sur un sel analogue (sel MDPA). La porosité du sel étudié est très faible (~1%) et sa perméabilité initiale varie de 4.5 d'ordres de grandeur. L'effet Klinkenberg n'est observé que pour les échantillons les moins endommagés. Le couplage poroélastique est presque négligeable. Le chargement déviatorique sous faible pression de confinement (1MPa) induit une augmentation de la perméabilité aux gaz à partir du seuil de dilatance due à la microfissuration. La mesure des vitesses des ondes ultrasonores lors de la compression uniaxiale montre une fermeture irréversible des microfissures préexistantes et l'ouverture de microfissures axiales perpendiculaires et parallèles à la direction de la contrainte permettant une détermination précise du seuil de dilatance. Sous une pression de confinement plus élevée (5 MPa), le matériau devient entièrement plastique, ce qui élimine l'effet d'endommagement. Sous chargement hydrostatique, la perméabilité au gaz diminue en raison d'auto-cicatrisation. Tous ces résultats montrent que le stockage souterrain de l'hydrogène dans le sel est la solution la plus sûre. Dans le cas des roches poreuses, l'injection d'hydrogène peut induire des réactions géochimiques entre les fluides et les minéraux et une consommation du stock d'hydrogène catalysée par des micro-organismes tolérant les conditions extrêmes des aquifères et réservoirs ultra-salins. Pour étudier ces phénomènes, nous avons développé un nouveau dispositif expérimental pour simuler cette activité dans des conditions (T=35°C, PH2=50bar, Pconfinement=200bar). Le gaz sortant est échantillonné automatiquement avec une vanne HP-BP et sa concentration est mesurée par le micro-chromatographe pour quantifier tout changement. Nous avons choisi de travailler avec le grès de Vosges où nous incubons la bactérie Shewanella putrefaciens qui réduit le fer en présence d’hydrogène. Son métabolisme et performance en tant que bactérie hydrogénotrophe ont d'abord été testés en batch sur une roche en poudre. Les résultats ont montré que ce type de bactéries peut réduire le fer présent en utilisant d'abord ses sources endogènes d'électrons puis l'hydrogène, préférentiellement, l'hydrogène dissous. En conditions triaxiales, l'activité bactérienne ne semble pas avoir d'impact significatif, quelles que soient la concentration initiale en hydrogène (70% ou 5%) et la fréquence d'échantillonnage. De nombreuses hypothèses sont proposées pour expliquer les différences observées entre les conditions en batch et triaxiales : l'hydrogène dissous dans les eaux résiduelles, la faible surface d'échange pour les réactions biogéochimiques dans le cas des carottes solides, la lenteur de la cinétique. Malgré les incertitudes liées à l'expérimentation, nos résultats préliminaires suggèrent que le stockage souterrain [...]Hydrogen produced from water electrolysis appears to be the best candidate for large- scale geological storage to cover the intermittency of renewable energy. It can be stored either in salt caverns or in porous rocks like saline aquifers and depleted oil and gas reservoirs. This thesis proposes an evaluation of the risk of gas leakage in the case of salt cavities and the risk of biogeochemical alteration of the gas stock in the case of porous reservoir rocks. Rock salt is a polycrystalline material with very low intrinsic permeability in undisturbed zones (around 10-21m2). It sealing capacity is due to the specific features of salt mechanical behavior and gas flow in such unconventional reservoirs (Klinkenberg effect). Deviatoric loading under low confining pressure (1MPa) induces a moderate increase in gas permeability from the dilatancy threshold due to microcracking disturbing the impermeability. So, understanding the complex relationship between permeability evolution and the mechanical and thermal solicitations is important to survey any possible risk of leakage. So, we performed a complete set of laboratory experiments on a rock salt specimen (MDPA in the East region of France). The porosity of the studied rock salt is very low (~1%) and the initial permeability varies over 4.5 orders of magnitude. Klinkenberg effect is only observed for the less damaged samples. The poroelastic coupling is almost negligible. Deviatoric loading under low confining pressure (1MPa) induces a moderate increase in gas permeability from the dilatancy threshold due to microcracking. Measurement of ultrasonic wave velocities during uniaxial compression showed an almost irreversible closure of pre-existing microcracks and the opening of axial microcracks that are perpendicular and parallel to the stress direction allowing a precise determination of the dilatancy threshold. Under higher confining pressure (5MPa), the material becomes fully plastic which practically eliminates damage. Under hydrostatic loading, gas permeability decreases because of the self-healing process. All these results give strong confidence in that underground hydrogen storage in salt caverns is the safest solution. In the case of porous reservoir rocks, hydrogen injection can induce geochemical redox reactions between the fluids and minerals and unwanted consumption of hydrogen stock catalyzed by microorganisms tolerating extreme conditions of deep saline aquifers and reservoirs.To study these phenomena, we developed a new experimental device to simulate the biochemical activity under extreme conditions (T=35°C, PH2=50bar, Pconfinement=200bar). The outflowing gas was automatically sampled with a HP-LP valve and the concentration was measured with a micro-gas chromatograph to quantify any change due to hydrogen bio-consumption. We chose to work on the Vosges sandstone where we incubate the Shewanella putrefaciens bacteria that reduce iron in the presence of hydrogen to produce energy. Its metabolism and performance as hydrogenotrophic bacteria were first tested in batch conditions on a rock powder. Results showed that this type of bacteria can reduce the iron present in the medium using endogenous sources of electrons first then hydrogen in the medium but preferentially dissolved hydrogen. Under triaxial conditions, the bacterial activity doesn’t seem to have a significant impact, whatever the initial hydrogen concentration (70% or 5%) and the sampling frequency (one or three days). Many hypotheses are proposed to explain the observed differences between batch and triaxial conditions: the scarcity of dissolved hydrogen in residual water, the low exchange surface for biogeochemical reactions in the case of solid core samples, the slow kinetic of hydrogen consumption by S. Despite the remaining uncertainties related to our experiments, our preliminary results suggest that the underground storage of pure hydrogen in porous reservoir rocks is not severely threatened by [...]
7
Arapova, Marina. "Synthesis and properties of the Ni-based catalysts for the valorization of ethanol and glycerol via steam reforming reaction for hydrogen production." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF031/document.
Повний текст джерелаАнотація:
Les trois familles catalytiques à base de perovskites contenant du Ni: massives [[LnFe1-x-yNiyMxO3-δ] (Ln=La, Pr; B=Co, Mn, Ru), sur support [mLnNi0.9Ru0.1О3/nMg-γ-Al2O3] (Ln = La, Pr) et structuré [mLaNi0.9Ru0.1О3/nMg-γ-Al2O3/mousses structurées] ont été synthétisés, caractérisés et testés dans les réactions de vaporeformage de l'éthanol et de glycérol. Les effets de la composition chimique et de la méthode de synthèse sur les propriétés structurelles et texturales, ainsi que sur la réductibilité des échantillons initiaux ont été évalués. L'utilisation préférentielle de Pr, Ni et Ru dans la composition de catalyseur a été démontrée pour toutes les familles. Le rôle essentiel de la modification du support γ-Al2O3 avec ≥ 10%mass de Mg introduit par imprégnation humide pour le catalyseur supporté a également été prouvé. Des catalyseurs de la composition optimale fournissant une activité élevée dans le vaporeformage de l'éthanol et du glycérol à T = 650 °C ont été trouvés: le meilleur catalyseur massif à base du précurseur PrFe0.6Ni0.3Ru0.1O3 fournit une activité élevée pendant au moins 7 h, grâce à la facilité de leur réduction et les propriétés d'oxydoréduction de l'oxyde de praséodyme formé. Les catalyseurs sur support 10-20% PrNi0.9Ru0.1O3/10-15%Mg-γ-Al2O3 fournissent le meilleur rendement en hydrogène (~ 90%) et la stabilité pendant ~ 20 heures. Le catalyseur structuré optimisé à base de la plaquette Ni-Al métallique fournit le rendement stable en hydrogène 80-87% dans l’oxy-vaporeformage d'éthanol dans les mélanges concentrés (concentration d'éthanol de 30%) dans un réacteur pilote pendant 40 heures. Les résultats obtenus rendent ces systèmes catalytiques structurés très prometteurs à utiliser dans les générateurs électrochimiques à base de piles à combustible avec l'utilisation de ressources renouvelables peu coûteuses comme bio-huileThe three catalytic families based on Ni-containing perovskites: massive [LnFe1-x-yNiyMxO3-δ] (Ln=La, Pr; B=Co, Mn, Ru), supported [mLnNi0.9Ru0.1О3/nMg-γ-Al2O3] (Ln = La, Pr) and structured [mLaNi0.9Ru0.1О3/nMg-γ-Al2O3/structured foams] were synthesized, characterized and tested in the reactions of the ethanol and glycerol steam reforming. The effects of the chemical composition and synthesis method on the structural and textural properties, as well as on reducibility of initial samples were evaluated. The preferred use of Pr, Ni and Ru in the catalyst composition was shown for all families. The essential role of the effective γ-Al2O3 support modification with the ≥10 % wt. of Mg introduced by wetness impregnation for the supported catalyst was also proved. Catalysts of the optimal composition providing a high activity in steam reforming of both ethanol and glycerol at T= 650 °С were found: the best massive catalyst based on the PrFe0.6Ni0.3Ru0.1O3 precursor provides high activity for at least 7 hours, which is explained by the ease of their reduction and the oxidation-reduction properties of the praseodymium oxide formed. Supported 10-20% PrNi0.9Ru0.1O3/10-15%Mg-γ-Al2O3 provide the greatest yield of hydrogen (~ 90%) and stability for ~ 20 hours. Structured catalyst based on the metal Ni-Al platelet provides the yield of hydrogen 80-87% in oxy-steam and steam reforming of ethanol in the concentrated mixtures (ethanol concentration of 30%) in a pilot reactor for 40 hours. The results obtained make these structured catalytic systems very promising to use in electrochemical generators based on fuel cells with the use of inexpensive renewable resource – bio-oil
8
Hendrickx, Johann. "Développement méthodologique pour l'étude des phénomènes d'interaction protéine-glucide." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT1023.
Повний текст джерелаАнотація:
Un ensemble de méthodes permettant d'étudier in silico des interactions protéine-glucide, primordiales dans de nombreux processus biologiques, sont proposées dans cette étude. En s'appuyant sur des informations fournies par la bio-cristallographie, il est devenu possible d'étudier à grande échelle les modalités d'interaction existantes entre ces deux entités moléculaires. Une étude statistique complète fut donc réalisée afin de déterminer aussi bien les tendances générales que les cas extrêmes observés dans les complexes protéine glucide. Les caractéristiques des interactions protéine glucide sont ainsi décrites, en particulier les liaisons hydrogène (LH) et le rôle des molécules d'eau. Un programme d'identification des LH et de reconstitution de leur(s) réseau(x) hypothétique(s) a été développé. Il comprend entre autres l'ajout putatif des hydrogènes, dans le cas où ils sont absents de la structure, notamment sur les groupes hydroxyles et les molécules d'eau. Une stratégie originale pour positionner de manière putative des molécules d'eau sur les sites de reconnaissance protéiques est également décrite. Cette stratégie a pour prétention de permettre le développement d'un protocole d'amarragemoléculaire protéine-glucide, les glucides et les molécules d'eau partageant sensiblement le même réseau de LH. Suite aux nombreuses anomalies décelées dans la PDB au niveau des glucides, une méthode d'identification et de vérification des structures 3D des glucides est également décrite. Elle a permis de limiter les bruits statistiques de cette étude. Environ 280 monosaccharides sous forme furanique et pyranique ont ainsi été référencés. La flexibilité intrinsèque des glucides a également amené à une étude approfondie de la conformation des glucides observée dans les structurescristallographiquesA set of methods to study in silico protein carbohydrate interactions, which are essential in many biological processes, are proposed in this study. Based on crystallographic data, it has become possible to study on a large scale the existing interaction modalities between the two molecular entities. A complete statistical study has thus been carried out to determine both the general trends and extreme cases observed in protein-carbohydrate complexes. The characteristics of protein-carbohydrate interactions are thus reported, in particular hydrogen bonds (HB) and the role of water molecules. A program to identify the HBs and reconstitute their hypothetical network(s) is being developed. This includes, in particular, the putative addition of hydrogens, if they are absent from the structure, especially on hydroxyl groups and water molecules. An original strategy for putatively positioning water molecules at protein recognition sites is also described. This strategy aims to allow the development of a protein-carbohydrate molecular docking protocol, as carbohydrates and water molecules share essentially the same HB network. As a result of the many carbohydrate anomalies detected in PDB, a method for identifying and verifying 3D carbohydrate structures has also been developed. It allowed to reduce the statistical noise in this study. About 280 monosaccharides in furanic and pyranic form were thus referenced. The intrinsic flexibility of carbohydrates also led to an in-depth study of the carbohydrate conformations observed in crystallographic structures
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Wu, Yu Qian Michelle. "Etude de procédés de conversion de biomasse en eau supercritique pour l'obtention d'hydrogène. : Application au glucose, glycérol et bio-glycérol." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0007/document.
Повний текст джерелаАнотація:
Des nouveaux procédés éco-efficients basés sur une meilleure utilisation des ressources renouvelables sont nécessaires pour assurer la continuité du développement énergétique. La thèse étudie le procédé de gazéification en eau supercritique (T>374°C et P>22,1 MPa) de la biomasse très humide pour l’obtention de l’hydrogène, molécule ayant un potentiel énergétique très intéressant à valoriser avec un impact environnemental très favorable. L’étude porte sur l’application du procédé à la biomasse modèle (solutions de glucose, glycérol et leur mélange) ainsi qu’au bioglycérol, résidu de la fabrication du biodiesel. Les propriétés du solvant et les mécanismes prépondérants développés par l’eau en phase souset supercritique peuvent être contrôlés par les paramètres opératoires imposés au processus : température, pression, concentration en molécules organiques et catalyseur alcalin, temps de réaction... Les études paramétriques des systèmes réactionnels ont été menées dans des réacteurs batch à deux échelles différentes, les phases résultantes étant caractérisées par des protocoles analytiques élaborés et validés dans le cadre de l’étude. Le suivi du milieu réactionnel en batch lors de son déplacement vers l’état supercritique a mis en évidence une conversion avancée des molécules organiques et une identification de certains intermédiaires générés. Parmi les paramètres étudiés, la température et le temps de réaction influent le plus le rendement à l’obtention d’hydrogène en présence de catalyseur (K2CO3) dans les réacteurs batch, rendements de 1,5 et 2 mol d’H2 respectivement par mol de glycérol et de glucose introduites. Les gaz obtenus contiennent des proportions variables d’hydrocarbures légers et du CO2. Environ 75% du carbone est converti en phase gaz et liquide (sous forme de carbone organique et inorganique), le restant étant déposé sous forme solide ou huileuse. L’analyse du solide généré (plus de 90% de C) laisse apparaître différentes phases, y compris la formation de nanoparticules sphériques. Enfin, la gazéification en réacteur continu du glycérol préchauffé a montré de meilleurs rendements en hydrogène que le procédé batch, pendant que celle du bioglycérol demande une évolution du procédé à cause de la précipitation en phase supercritique des sels contenus dans le réactant. En conclusion, la gazéification en eau supercritique de la biomasse peut être considérée comme une alternative intéressante à d’autres procédés physico-chimiques de production de l’hydrogène. L’amélioration du procédé sera possible par son intensification menée en parallèle avec l’utilisation de matériaux plus performants et le contrôle de la salinité de la phase réactanteSupercritical water (T > 374 ° C and P > 22.1 MPa) gasification of wet biomass for hydrogen production is investigated. This process converts a renewable resource into a gas, which is mainly composed of hydrogen and hydrocarbons with interesting energy potential, and which can be separated at high pressure. In addition, the greenhouse gas effect of the process is zero or negative. Model biomasses (glucose, glycerol and their mixture) and bio-glycerol, residue from bio-diesel production, have been gasified by different processes: two-scale batch reactors (5 mL and 500 mL) and a continuous gasification system. Supercritical water acts as a reactive solvent, its properties can be adjusted by the choice of the experimental (P, T) couple. The operating parameters, e.g. temperature, pressure, concentration of biomass and alkaline catalysts, reaction time… allow favoring certain reaction mechanisms. In order to characterize the processes, specific analytical protocols have been developed and validated. The intermediates, formed during the heating time in the batch reactors, have been identified. Among the investigated operating parameters, temperature and reaction time have the greatest influence on the hydrogen production in batch reactors. In the presence of catalyst (K2CO3), H2 yields of 1.5 mol/mol glucose and 2 mol/mol glycerol have been respectively observed. The obtained gas contains different proportions of light hydrocarbons and CO2. About 75% of the carbon is converted into gas and liquid (in form of organic and inorganic carbon). The conversion leads also to a solid or oily residue. In the generated solid phase (composed over 90% of C), spherical nanoparticles are observed via electronic microscopy. The hydrogen production from glycerol is improved in the continuous process compared to batch reactors, however, bio-glycerol supercritical water gasification requests process improvement due to the precipitation of the salt contained in the reactant. In conclusion, supercritical water gasification of biomass can be considered as an promising alternative process for hydrogen production. The process should be improved by more performing equipments and by the control of the salinity content of the crude biomass
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Eskandari, Azin. "A preliminary theoretical and experimental study of a photo-electrochemical cell for solar hydrogen production." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC104.
Повний текст джерелаАнотація:
Afin de relever le défi énergétique et climatique du 21ième siècle qui s’annonce, une solution consiste, pour valoriser la ressource solaire, à mettre au point des procédés de production de vecteurs énergétiques stockables par photosynthèse artificielle permettant la synthèse de carburants solaires, en particulier l’hydrogène. La compréhension de ses procédés et l’obtention de performances cinétiques et énergétiques élevées nécessitent le développement de modèles de connaissance génériques, robustes et prédictifs considérant le transfert de rayonnement comme processus physique contrôlant le procédé à plusieurs échelles mais aussi les différents autres phénomènes intervenant dans la structure ou la réification du modèle.Dans le cadre de ce travail de doctorat, le procédé photo-réactif au cœur de l’étude était la cellule photo-électrochimique. D’un fonctionnement plus complexe que le simple photoréacteur, avec une photo-anode et une (photo)cathode, la cellule photo-électrochimique dissocie spatialement les étapes d’oxydation et de réduction. En se basant à la fois sur la littérature existante (essentiellement dans le domaine de l’électrochimie) et en déployant les outils développés par l’équipe de recherche sur le transfert de rayonnement et la formulation du couplage thermocinétique, il a été possible d’établir des indicateurs de performance des cellules photo-électrochimiques.En parallèle de l’établissement de ce modèle, une démarche expérimentale a été entreprise en se basant tout d’abord sur une cellule commerciale de type Grätzel (DS-PEC) indiquant les tendances générales de tels convertisseurs de l’énergie des photons avec en particulier une chute de l’efficacité énergétique en fonction de la densité incidente de flux de photons. Un dispositif expérimental modulable (Minucell) a aussi été développé et validé afin de caractériser des photo-anodes de différentes compositions comme des électrodes de TiO2 imprégnées de chromophore pour un fonctionnement en cellule de Grätzel ou bien des électrodes d’hématite Fe2O3 (SC-PEC) où le semiconducteur joue à la fois les fonctions d’absorption des photons et de conduction des porteurs de charges. Surtout, le dispositif Minucell a permis de tester, caractériser et modéliser le comportement d’une cellule photo-électrochimique de type bio-inspiré pour la production d’H2 utilisant à la photo-anode un catalyseur moléculaire Ru-RuCat (développé par ICMMO Orsay/CEA Saclay) et à la cathode un catalyseur CoTAA (développé par LCEMCA Brest). Minucell a été utilisé pour caractériser chaque élément constitutif d’une cellule photo-électrochimique puis la cellule dans son ensemble, confirmant les tendances et observations obtenues sur les efficacités énergétiques.Ce travail préliminaire ouvre de très nombreuses perspectives de recherche, il pose des bases communes entre électrochimie et génie des systèmes photo-réactifs et donne des pistes quant à la conception et l’optimisation cinétique et énergétique des cellules photo-électrochimiques pour la production d’hydrogène et de carburants solairesIn order to meet the energy and climate challenge of the coming 21st century, one solution consists of developing processes for producing storable energy carriers by artificial photosynthesis to synthesize solar fuels, in particular hydrogen, in order to valorize the solar resource. The understanding of these processes and the achievement of high kinetic and energetic performances require the development of generic, robust and predictive knowledge models considering radiative transfer as a physical process controlling the process at several scales but also including the various other phenomena involved in the structure or reification of the model.In this PhD work, the photo-reactive process at the heart of the study was the photo-electrochemical cell. More complex than the simple photoreactor, with a photo-anode and a (photo)cathode, the photo-electrochemical cell spatially dissociates the oxidation and reduction steps. Based both on the existing literature (mainly in the field of electrochemistry) and by deploying the tools developed by the research team on radiative transfer and thermokinetic coupling formulation, it was possible to establish performance indicators of photo-electrochemical cells.In parallel to the establishment of this model, an experimental approach was undertaken based first on a commercial Grätzel-type cell (DS-PEC) indicating the general trends of such photon energy converters with in particular a drop in energy efficiency as a function of the incident photon flux density. A modular experimental device (Minucell) has also been developed and validated in order to characterize photo-anodes of different compositions such as chromophore impregnated TiO2 electrodes for operation in Grätzel cells or Fe2O3 hematite electrodes (SC-PEC) where the semiconductor plays both the functions of photon absorption and charge carrier conduction. Above all, the Minucell device allowed to test, characterize and model the behavior of a bio-inspired photo-electrochemical cell for H2 production using at the photo-anode a Ru-RuCat molecular catalyst (developed by ICMMO Orsay/CEA Saclay) and at the cathode a CoTAA catalyst (developed by LCEMCA Brest). Minucell was used to characterize each constituent element of a photo-electrochemical cell and then the cell as a whole confirming the trends and observations obtained on energy efficiencies.This preliminary work opens up a wide range of research prospects, lays common ground between electrochemistry and photo-reactive systems engineering, and provides insights into the design and kinetic and energy optimization of photo-electrochemical cells for the production of hydrogen and solar fuels
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Hagemann, Birger. "Numerical and Analytical Modeling of Gas Mixing and Bio-Reactive Transport during Underground Hydrogen Storage." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0328/document.
Повний текст джерелаАнотація:
En rapport avec la transition énergétique, d’importantes capacités de stockage énergétique sont nécessaires pour intégrer la forte variation de la production énergétique au travers des centrales éoliennes et photovoltaïques. La transformation de l’énergie électrique en énergie chimique sous forme d’hydrogène est l’une des possibles techniques. La technologie de stockage de l’hydrogène souterrain, selon laquelle l’hydrogène est stocké dans les formations souterraines semblables au stockage du gaz naturel est actuellement un axe de recherche de plusieurs états européens. Par comparaison au stockage du gaz naturel dans les formations souterraines et qui est établie depuis de nombreuses années, l'hydrogène a montré des différences significatives dans son comportement hydrodynamique et biochimique. Ces aspects ont été étudiés dans la présente thèse en utilisant différentes approches analytiques et numériquesIn the context of energy revolution large quantities of storage capacity are required for the integration of strongly fluctuating energy production from wind and solar power plants. The conversion of electrical energy into chemical energy in the form of hydrogen is one of the technical possibilities. The technology of underground hydrogen storage (UHS), where hydrogen is stored in subsurface formations similar to the storage of natural gas, is currently in the exploratory focus of several European countries. Compared to the storage of natural gas in subsurface formations, which is established since many years, hydrogen shown some significant differences in its hydrodynamic and bio-chemical behavior. These aspects were investigated in the present thesis by different analytical and numerical approaches
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Hajj, Viviane. "Transfert couplé électron/proton et coupure de liaisons dans les systèmes bio-inspirés : études mécanistiques par électrochimie de l'oxydation d'une paire guanine-cytosine et de la coupure réductrice de liaison oxygène-oxygène assistée en présence d'un groupe donneur de proton." Paris 7, 2011. https://tel.archives-ouvertes.fr/tel-00712330.
Повний текст джерелаАнотація:
Le transfert d'électron associé au transfert de proton ou à la coupure de liaison est un processus omniprésent dans les systèmes naturels et biologiques. Comprendre les enjeux mécanistiques impliqués dans le fonctionnement de ces systèmes permet de les exploiter et de pouvoir les imiter. Deux systèmes bio-inspirés ont été étudiés par électrochimie directe, l'oxydation d'une paire de base guanine-cytosine et la réduction d'un cycloperoxyde assistée par la présence d'un groupe donneur de proton. Le premier système associe le transfert d'électron au transfert de proton alors que le second illustre le couplage entre le transfert d'électron et de proton et la coupure de liaison. L'appariement entre les bases de l'ADN par liaison hydrogène n'a aucun effet sur la cinétique et la thermodynamique de l'oxydation de la guanine. La réaction est cinétiquement contrôlée par la première étape du transfert électronique et le mécanisme impliqué est séquentiel. La coupure réductrice de la liaison O-O du cycloperoxyde assistée par la présence d'un groupe donneur de proton est comparée à un autre système où la fonction acide carboxylique est remplacée par un groupe méthoxy. Un décalage de 700 mV est observé entre le potentiel de pic des deux composés indiquant que le gain thermodynamique offert par l'étape de protonation est exprimé dans la cinétique de la réaction. Par conséquent le transfert d'électron dissociatif et le transfert de proton sont tous concertés. Un nouveau modèle cinétique simplifié a été établie pour décrire la dynamique de ce type de mécanisme appelé « tout concerté »The electron transfer associated with proton transfer or bond breaking is an important process often presented in naturel and biological System. Understanding the mechanistic issues involved in the operation of these Systems allows us to understand, imitate and exploit them. Two bio-inspired Systems have been studied by direct electrochemistry, the oxidation of a guanine paired to a cytosine with hydrogen bonds and the reduction of a cycloperoxide assisted by the presence of a proton donnor group. The match between DMA bases through hydrogen bonding has no effect on the kinetic and thermodynamic of the oxidation of a guanine. The reaction is kinetically controlled by the first stage of electronic transfer and the mechanism involved is sequentiel. The reductive cleavage of the O-O bond of the cycloperoxide assisted by the presence of a proton donor group is compared to another System in which the carboxylic acid function is replaced by a methoxy group. An offset of 700 mV was observed between the pic potential of both compounds indicating that the gain offered by the protonation step is expressed in the kinetic of the reaction. Consequently the dissociative electron transfer and the proton transfer are al concerted. A new simplified kinetic model was established to describe the dynamics of such a mechanism called « all in concert »
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Gentil, Solène. "Enzymes et catalyseurs bio-inspirés immobilisés sur électrodes nanostructurées pour l'élaboration de piles H2/air sans métaux nobles." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAV058/document.
Повний текст джерелаАнотація:
Le développement de technologies de l’énergie alternatives à la combustion des ressources fossiles est un enjeu majeur pour réduire l’émission des gaz à effet de serre et développer une économie durable. Dans cette optique, les piles à combustible à membrane échangeuses de protons (PEMFC) utilisent le platine en tant que catalyseur pour transformer l’énergie chimique en énergie électrique, en réduisant l’oxygène de l’air en eau et en oxydant l’hydrogène en protons. Dans la nature, les enzymes à cuivre et les hydrogénases catalysent respectivement ces réactions. Ces dernières, ainsi que des complexes bio-inspirés de leur site actif, ont été envisagés en tant qu’alternatives au platine, métal noble et coûteux. Ainsi, un complexe mononucléaire bisdiphosphine de nickel renfermant des acides aminés arginines en troisième sphère de coordination a été immobilisé sur une matrice de nanotubes de carbone (NTCs). Cette anode a démontré d’excellentes performances pour oxyder l’hydrogène avec des densités de courant élevées et sur une large gamme de pH. Son utilisation dans une PEMFC a permis d’obtenir une densité de puissance de 15 mW.cm-2, seulement cinq fois inférieure à celle d’une pile classique à base de platine préparée dans les mêmes conditions. Concernant la catalyse de réduction de l’oxygène, des méthodes covalentes ont été développéespour réaliser la connexion électronique directe de laccase de Trametes sp C30, ainsi qu’un mutant de cetten enzymesur matrice de NTCs L’’association du catalyseur de nickel avec une cathode à base de bilirubine oxydase immobilisée sur NTCs a permis de proposer un nouveau concept de pile hybride enzymatique/bio-inspirée. Une densité de puissance de l’ordre de 1,8 mW.cm-2 et une force électromotrice proche de 1V ont ainsi été mesurées pour cette pile sans métaux nobles. Le greffage de complexes de cuivre mono- et dinucléaires, bio-inspirés du site actif d’enzymes à cuivre et actifs vis-à-vis de la réduction de l’oxygène a enfin permis d’élaborer la première pile H2/air ne renfermant que des catalyseurs moléculaires et sans métaux nobles. Cette dernière délivre une densité de puissance de 160 µW.cm-2New energy technologies alternative to fossil fuels utilization is a key issue to mitigate greenhouse gases emission and develop a sustainable economy. In this context, platinum-based proton exchange membrane fuel cells use oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) to convert chemical energy into electrical energy. In nature multicopper oxidases and hydrogenases catalyze these two reactions, respectively. These enzymes and corresponding bioinspired catalysts have been used as alternatives to the rare and expensive platinum metal. First, a mononuclear bis-diphosphine nickel complex surrounded by arginine residues was immobilized onto carbon nanotubes (CNTs) and demonstrated excellent performances for HOR developing high current densities over a wide range of pH. This anode was integrated in a PEMFC, which achieved high power densities (15 mW cm-2), only five times lower as compared to classical PEMFC prepared under similar conditions. Regarding ORR catalysis, we covalently grafted LLaccases from Trametes sp C30 multicopper oxidases onto NTCs electrodes and achieved direct electron transfer. Using, bilirubin oxidase deposited on CNTs at the cathode side, we proposed a new concept of hybrid enzymatic/bio-inspired H2/air fuel cell. This hydrogen fuel cell delivered 1.8 mW.cm-2 and a high open circuit voltage of 1V. Finally, various copper complexes inspired from the active sites of copper enzymes were assessed for ORR and the first H2/air fuel cell containing noble metal-free molecular catalysts at both electrodes is reported, achieving 160 µW.cm-2 power density
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Yu-Wu, Qian Michelle. "Étude de procédés de conversion de biomasse en eau supercritique pour l'obtention d'hydrogène. Application au glucose, glycérol et bio-glycérol." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2012. http://tel.archives-ouvertes.fr/tel-00690467.
Повний текст джерелаАнотація:
Des nouveaux procédés éco-efficients basés sur une meilleure utilisation des ressources renouvelables sont nécessaires pour assurer la continuité du développement énergétique. La thèse étudie le procédé de gazéification en eau supercritique (T>374°C et P>22,1 MPa) de la biomasse très humide pour l'obtention de l'hydrogène, molécule ayant un potentiel énergétique très intéressant à valoriser avec un impact environnemental très favorable. L'étude porte sur l'application du procédé à la biomasse modèle (solutions de glucose, glycérol et leur mélange) ainsi qu'au bioglycérol, résidu de la fabrication du biodiesel. Les propriétés du solvant et les mécanismes prépondérants développés par l'eau en phase sous- et supercritique peuvent être contrôlés par les paramètres opératoires imposés au processus : température, pression, concentration en molécules organiques et catalyseur alcalin, temps de réaction... Les études paramétriques des systèmes réactionnels ont été menées dans des réacteurs batch à deux échelles différentes, les phases résultantes étant caractérisées par des protocoles analytiques élaborés et validés dans le cadre de l'étude. Le suivi du milieu réactionnel en batch lors de son déplacement vers l'état supercritique a mis en évidence une conversion avancée des molécules organiques et une identification de certains intermédiaires générés. Parmi les paramètres étudiés, la température et le temps de réaction influent le plus le rendement à l'obtention d'hydrogène en présence de catalyseur (K2CO3) dans les réacteurs batch, rendements de 1,5 et 2 mol d'H2 respectivement par mol de glycérol et de glucose introduites. Les gaz obtenus contiennent des proportions variables d'hydrocarbures légers et du CO2. Environ 75% du carbone est converti en phase gaz et liquide (sous forme de carbone organique et inorganique), le restant étant déposé sous forme solide ou huileuse. L'analyse du solide généré (plus de 90% de C) laisse apparaître différentes phases, y compris la formation de nanoparticules sphériques. Enfin, la gazéification en réacteur continu du glycérol préchauffé a montré de meilleurs rendements en hydrogène que le procédé batch, pendant que celle du bioglycérol demande une évolution du procédé à cause de la précipitation en phase supercritique des sels contenus dans le réactant. En conclusion, la gazéification en eau supercritique de la biomasse peut être considérée comme une alternative intéressante à d'autres procédés physico-chimiques de production de l'hydrogène. L'amélioration du procédé sera possible par son intensification menée en parallèle avec l'utilisation de matériaux plus performants et le contrôle de la salinité de la phase réactante.
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Liu, Hong, and 劉紅. "Bio-hydrogen production from carbohydrate-containing wastewater." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31244518.
Повний текст джерела
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McAnoy, Andrew M. Sait Michelle Pantelidis Sue. "Establishment of a vaporous Hydrogen Peroxide bio-decontamination capability." Fishermans Bend, Victoria : Defence Science and Technology Organisation, 2007. http://hdl.handle.net/1947/8654.
Повний текст джерела
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Appressi, Lorenzo. "Biogas and bio-hydrogen: production and uses. A review." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9071/.
Повний текст джерелаАнотація:
The first part of this essay aims at investigating the already available and promising technologies for the biogas and bio-hydrogen production from anaerobic digestion of different organic substrates. One strives to show all the peculiarities of this complicate process, such as continuity, number of stages, moisture, biomass preservation and rate of feeding. The main outcome of this part is the awareness of the huge amount of reactor configurations, each of which suitable for a few types of substrate and circumstance. Among the most remarkable results, one may consider first of all the wet continuous stirred tank reactors (CSTR), right to face the high waste production rate in urbanised and industrialised areas. Then, there is the up-flow anaerobic sludge blanket reactor (UASB), aimed at the biomass preservation in case of highly heterogeneous feedstock, which can also be treated in a wise co-digestion scheme. On the other hand, smaller and scattered rural realities can be served by either wet low-rate digesters for homogeneous agricultural by-products (e.g. fixed-dome) or the cheap dry batch reactors for lignocellulose waste and energy crops (e.g. hybrid batch-UASB).
The biological and technical aspects raised during the first chapters are later supported with bibliographic research on the important and multifarious large-scale applications the products of the anaerobic digestion may have. After the upgrading techniques, particular care was devoted to their importance as biofuels, highlighting a further and more flexible solution consisting in the reforming to syngas. Then, one shows the electricity generation and the associated heat conversion, stressing on the high potential of fuel cells (FC) as electricity converters. Last but not least, both the use as vehicle fuel and the injection into the gas pipes are considered as promising applications. The consideration of the still important issues of the bio-hydrogen management (e.g. storage and delivery) may lead to the conclusion that it would be far more challenging to implement than bio-methane, which can potentially “inherit” the assets of the similar fossil natural gas.
Thanks to the gathered knowledge, one devotes a chapter to the energetic and financial study of a hybrid power system supplied by biogas and made of different pieces of equipment (natural gas thermocatalitic unit, molten carbonate fuel cell and combined-cycle gas turbine structure). A parallel analysis on a bio-methane-fed CCGT system is carried out in order to compare the two solutions. Both studies show that the apparent inconvenience of the hybrid system actually emphasises the importance of extending the computations to a broader reality, i.e. the upstream processes for the biofuel production and the environmental/social drawbacks due to fossil-derived emissions. Thanks to this “boundary widening”, one can realise the hidden benefits of the hybrid over the CCGT system.
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Pierra, Mélanie. "Couplage de la fermentation sombre et de l’électrolyse microbienne pour la production d’hydrogène : formation et maintenance du biofilm électro-actif." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20150/document.
Повний текст джерелаАнотація:
L'hydrogène, qui constitue une solution alternative et durable à l’usage d’énergies fossiles, est produit essentiellement par reformage de combustibles fossiles (95%). Des filières de production plus soucieuses de l'environnement sont envisagées. Deux familles de technologies sont explorées: 1) par décomposition thermochimique ou électrochimique de l'eau et 2) à partir de différentes sources de biomasse. Parmi celles-ci, les cellules d'électrolyse microbienne ou «Microbial electrolysis cell (MEC)» permettent de produire de l'hydrogène par électrolyse de la matière organique. Une MEC consiste en une cathode classique qui assure la production d'hydrogène par la réduction électrochimique de l'eau, associée à une bioanode qui oxyde des substrats organiques en dioxyde de carbone. Ce processus d'oxydation n'est possible que grâce au développement sur l'anode d'un biofilm microbien électroactif qui joue le rôle d'électro-catalyseur. Par rapport aux procédés courants d'électrolyse de l'eau, une MEC requière un apport énergétique 5 à 10 fois plus faibles. En outre, les procédés « classiques » de production de bio-hydrogène par voie fermentaire en cultures mixtes convertissent des sucres avec des rendements limités à 2-3 moles d'hydrogène par mole d'hexose tout en coproduisant des acides organiques. Alimenté par de l'acétate, une MEC produit au maximum 3 moles d'hydrogène/mole d'acétate. Le couplage de la fermentation à un procédé d'électrolyse microbienne pourrait donc produire de 8 à 9 moles d'hydrogène/mole d'hexose, soit un grand pas vers la limite théorique de 12 moles d'hydrogène/mole d'hexose. L'objectif de cette thèse est d'analyser les liens entre la structure des communautés microbiennes dans les biofilms électroactifs et en fermentation, les individus qui les composent et les fonctions macroscopiques (électroactivité du biofilm, production d'hydrogène) qui leur sont associées dans des conditions permettant de réaliser le couplage des deux procédés. L'originalité de cette étude a été de travailler en milieu salin (30-35 gNaCl/L), favorable au transport de charges dans l'électrolyte de la MEC. Dans un premier temps, la faisabilité de la fermentation en conditions salines (3-75 gNaCl/L) a été démontrée en lien avec l'inhibition de la consommation de l'hydrogène produit et une forte prédominance d'une nouvelle souche de Vibrionaceae à des concentrations en sel supérieures à 58 gNaCl/L. D'autre part, la mise en œuvre de biofilms électroactifs dans des conditions compatibles avec la fermentation sombre a permis la sélection d'espèces dominantes dans les biofilms anodiques et présentant des propriétés électroactives très prometteuses (Geoalkalibacter subterraneus et Desulfuromonas acetoxidans) jusqu'à 8,5 A/m². En parallèle, la sélection microbienne opérée lors d'une méthode d'enrichissement utilisée pour sélectionner ces espèces à partir d'une source d'inoculum naturelle sur leur capacité à transférer leurs électrons à des oxydes de Fer(III) a été étudiée. Une baisse des performances électroactives du biofilm liée à une divergence de sélection microbienne dans ces deux techniques de sélection mène à limiter le nombre de cycle d'enrichissement sur Fer(III). Cependant, l'enrichissement sur Fer(III) reste une alternative efficace de pré-selection d'espèces électroactives qui permet une augmentation de rendement faradique de 30±4% à 99±8% par rapport au biofilm obtenu avec un inoculum non pré-acclimaté. Enfin, l'ajout d'espèces exogènes issues de la fermentation sombre sur le biofilm électroactif a révélé une baisse de l'électroactivité du biofilm se traduisant par une diminution de la densité de courant maximale produite. Cette baisse pourrait s'expliquer par à une diminution de la vitesse de transfert du substrat due à un épaississement apparent du biofilm. Cependant, un maintien de sa composition microbienne et de la quantité de biomasse laisse supposer une production d'exopolymères (EPS) dans le biofilm en situation de couplageNowadays, alternative and sustainable solutions are proposed to avoid the use of fossil fuel. Hydrogen, which constitutes a promising energy vector, is essentially produced by fossil fuel reforming (95%). Environmentally friendly production systems have to be studied. Two main families of technologies are explored to produce hydrogen: 1) by thermochemical and electrochemical decomposition of water and 2) from different biomass sources. Among those last ones, microbial electrolysis cells (MEC) allow to produce hydrogen by electrolysis of organic matter. A MEC consists in a classical cathode, which provides hydrogen production by electrochemical reduction of water, associated to a bio-anode that oxidizes organic substrates into carbon dioxide. This process is only possible because of the anodic development of an electroactive microbial biofilm which constitutes an electrocatalyst. In comparison to classical water electrolysis process, a MEC requires 5 to 10 times less electrical energy and therefore reduces the energetic cost of produced hydrogen. Furthermore, classical process of dark fermentation in mixed cultures converts sugars (saccharose, glucose) to hydrogen with a limited yield of 2-3 moles of hydrogen per mole of hexose because of the coproduction of organic acids (mainly acetic and butyric acids). Fed with acetate, a MEC can produce up-to 3 moles of hydrogen per mole of acetate. Therefore, the association of these two processes could permit to produce 8 to 9 moles of hydrogen per mole of hexose, which represents a major step toward the theoretical limit of 12 moles of hydrogen per mole of hexose.Therefore, this work aims at analyzing the relationship between microbial community structures and compositions and the associated macroscopic functions (biofilm electroactive properties, hydrogen production potential) in electroactive biofilms and in dark fermentation in conditions allowing the coupling of the two processes. The originality of this study is to work in saline conditions (30-35 gNaCl/L), which favors the charges transfer in the MEC electrolyte.First of all, feasibility of dark fermentation in saline conditions (3-75 gNaCl/L) has been shown. This was linked to an inhibition of produced hydrogen consumption and the predominance of a new Vibrionaceae species at salt concentrations higher than 58 gNaCl/L. Secondly, electroactive biofilm growth in conditions compatibles to dark fermentation (pH 5.5-7 and fed with different organic acids) allowed to select dominant microbial species in anodic biofilms that present promising electroactive properties (Geoalkalibacter subterraneus and Desulfuromonas acetoxidans) with maximum current densities up to 8.5 A/m². In parallel, the microbial selection occurring during iron-reducing enrichment method used to select species from a natural inoculum source and based on their capacity to transfer electrons to iron oxydes (Fe(III)) has been studied. A decrease of electroactive performances of the biofilm linked to the divergence of microbial selection led to a limitation of the number of iron-enrichment steps. However, enrichment on Fe(III) presents an efficient alternative to pre-select electroactive species with an increase of coulombic efficiency from 30±4% to 99±8% in comparison with a biofilm obtained with a non-acclimated inoculum. Finally, the addition of exogenous bacteria from a dark fermenter on the electroactive biofilm revealed a decrease of electroactivity with a decrease of maximum current density produced. This diminution could be explained by a lower substrate transfer due to an apparent thickening of the biofilm. Nevertheless, the stability of microbial composition and of bacterial quantity on the anode suggests that a production of exopolymers (EPS) occurred
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Ozkan, Leyla. "Dark Fermentative Bio-hydrogen Production From Sugar-beet Processing Wastes." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610980/index.pdf.
Повний текст джерелаАнотація:
In this study, bio-hydrogen generation potential of sugar-beet processing wastes (sugar-beet processing wastewater and beet-pulp) through dark fermentation was investigated. For this purpose, four different experimental set-ups were used.
In the first set-up, sugar-beet processing wastewater was used along with four different cultures to investigate the effect of culture type on bio-hydrogen production. In addition, unseeded reactor was prepared to investigate bio-hydrogen production potential of indigenous microorganisms. The highest bio-hydrogen production yield (87.7 mL H2/g COD) was observed in the unseeded reactor. In the second set-up, beet-pulp was compared with sugar-beet processing wastewater in terms of bio-hydrogen generation potentials at an initial COD level of 4.5 g/L. In the third set-up, bio-hydrogen productivities of only beet-pulp and co-digestion of beet-pulp and sugar-beet processing wastewater at high COD values were investigated. The results of third set-up revealed that the reactor fed by 20 g/L COD beet-pulp provided the highest bio-hydrogen production yield (95.6 mL H2 /g COD). Finally, in the fourth set-up, the effects of five different pretreatment methods on solubilization of beet-pulp were investigated. Then, three out of five pretreatment methods were chosen to compare the corresponding bio-hydrogen productivities. Maximum bio-hydrogen production yield (115.6 mL H2/g COD) was observed in reactor which contained alkaline pretreated beet-pulp.
Based on the results obtained in this study, it is postulated that, bio-hydrogen production from sugar-beet processing wastes by dark fermentation can not only enable waste minimization but also contribute to sustainability via valuable bio-based product formation from wastes, namely bio-hydrogen.
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Asous, Nadia K. "Hydrogen Atom Transfer Reactivity of Bio-inspired Unsymmetrical Dicopper– oxo/peroxo Complexes." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1533245264093817.
Повний текст джерела
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PELLAVIO, GIORGIA. "Aquaporins permeability to hydrogen peroxide may control oxidative stress." Doctoral thesis, Università degli studi di Pavia, 2021. http://hdl.handle.net/11571/1448466.
Повний текст джерелаАнотація:
Transmembrane water channel proteins, known as aquaporins (AQPs), play a pivotal role in many biological processes including volume regulation, cell migration and proliferation, and adipocyte metabolism. Recently, it has been demonstrated the involvement of some AQPs, known as “peroxiporins”, in the transport of hydrogen peroxide (H2O2). H2O2 is the most abundant and stable reactive oxygen species (ROS) in living cells and H2O2 can have different effects depending on its concentration. Physiological levels of H2O2 induce positive adaptive responses acting as second messenger, while excessive levels provoke negative effects as apoptosis and cell death.
Since AQPs allow the diffusion of H2O2 across plasma membranes to the extracellular fluid, they have been considered as a possible ROS scavenging mechanism. Until now, AQP1, 3, 5, 8, 9 and 11 are the mammalian AQPs involved in H2O2 diffusion. This project aims to understand the mechanism of AQPs as peroxiporins in mediating H2O2 diffusion through cellular plasma membrane.
The guiding thread of this thesis was, on the one hand, the analysis of the role of peroxiporins in some pathophysiological conditions and, on the other, the identification and characterization of new gating modulators.
In particular this thesis aimed:
1. to investigate the negative role of human Papillomavirus (HPV) infection on the aquaporin-mediated hydrogen peroxide elimination which affects human sperm functioning;
2. to clarify AQPs/peroxiporins involvement in malignant pleural mesothelioma progression (MPM);
3. to identify and characterize new aquaporin modulators to counteract the oxidative stress.
As a whole, AQPs permeability alteration (and sensitivity to oxidative stress) in HPV infection and in MPM seems to reduce the fertility of sperm cells and make MPM cells resistant to conventional chemotherapy, respectively. The possibility to modify the gating of the AQPs and ROS scavenging opens to new therapeutic strategies for the treatment of debilitating diseases involving oxidative stress namely neurodegenerative diseases and cancer.
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Redwood, Mark D. "Bio-hydrogen and biomass-supported palladium catalyst for energy production and waste-minimisation." Thesis, University of Birmingham, 2008. http://etheses.bham.ac.uk//id/eprint/3135/.
Повний текст джерелаАнотація:
The project objective was to advance the development of the H2 economy by improving biological H2 production in a sustainable way. Pseudo-continuous H2 production was achieved with improved efficiency, via the bacterial fermentation of sugars in a dual-bioreactor (‘upstream system’) comprising a dark fermentation coupled to a photofermentation. Excess biomass from the upstream system was used to recover palladium from solution, producing ‘palladised biomass’ (Bio-Pd(0)), which was useful in the construction of bioinorganic catalytic anodes for the electricity generation from bio-H2 using a polymer electrolyte membrane fuel cell (‘downstream system’). Furthermore, the catalytic usefulness of Bio-Pd(0) was confirmed in several reactions in comparison with other palladised biomasses and with Pd(0) made chemically. The upstream modules: Escherichia coli dark fermentation and Rhodobacter sphaeroides photofermentation, were investigated and developed separately, before coupling the two stages by the novel application of electrodialysis (accelerated membrane separation). The biorecovery and testing of palladium bionanocatalyst are described, before the production of fuel cell catalyst using waste biomass. The technical challenges and potential benefits of biohydrogen production are discussed and contrasted with those of competing biofuel technologies.
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Ressouche, Emilie. "Nanostructuration de mélanges de polymères supra(macro)moléculaires." Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066758.
Повний текст джерелаАнотація:
Les polymères supramoléculaires sont des polymères constitués ou liés entre eux par des interactions non covalentes. Ils peuvent être des polymères classiques reliés par des groupements associatifs, appelés ici « polymères supramacromoléculaires », ou des petites molécules assemblées les unes aux autres, formant un « polymère supramoléculaire ». En solution, les polymères supramoléculaires, suivant leur structure, peuvent s’enchevêtrer, menant à des gels thermoréversibles. En l’absence de solvant, les polymères supramacromoléculaires, contrairement aux polymères classiques, sont dynamiques, et peuvent donc présenter des propriétés intéressantes (auto-réparation, adhésion, nanostructures organisées et stimulables). Lors de ce projet, des mélanges de polymères supramoléculaires et supramacromoléculaires à base de bis-urées sont réalisés et étudiés, en présence ou en absence de solvant. En solution, des synergies sont observées et caractérisées, à l’échelle microscopique (étude de la microstructure) et macroscopique (propriétés rhéologiques). En l’absence de solvant, des petites molécules sont incorporées au sein de matrices de polymères supramacromoléculaires d’une part, et des mélanges de polymères supramacromoléculaires sont réalisés d’autre part. Les matériaux obtenus sont étudiés à l’échelle microscopique (microstructure) et macroscopique (propriétés rhéologiques et mécaniques)Supramolecular polymers are polymers constituted or linked by non-covalent interactions. They can be classical polymers linked by stickers, named here “supramacromolecular polymers”, or self-assembled low molecular weight molecules, leading to a “supramolecular polymer”. In solution, supramolecular polymers, depending on their shape, can entangle and form thermoreversible gels. In bulk, unlike classical polymers, supramacromolecular polymers are dynamic, thus they can exhibit interesting properties (self-repair, adhesion, stimuli-responsive self-organized nanostructures). The aim of this thesis is to study bis-urea-based supra(macro)molecular polymer mixtures, in solution or in bulk. In solution, synergies are characterized, at microscopic (microstructure) and macroscopic scale (rheology). In bulk, low molecular weight molecules are mixed with supramacromolecular polymers on one hand, and supramacromolecular polymers blends are created on the other hand. The materials are studied both at microscopic (microstructure) and macroscopic scale (rheology, mechanical properties)
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Gambari, Laura <1985>. "Hydrogen Sulfide (H2S) Based Therapeutics for Bone Diseases: Translating Physiology to Treatments." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7535/1/gambari_laura_tesi.pdf.
Повний текст джерелаАнотація:
Much progress has been made in the past decade in elucidating the physiological, pathophysiological and pharmacological role of Hydrogen Sulphide (H2S). Recently a function of H2S virtually in every tissue of the human organism has emerged. However, the H2S-mediated regulation of bone homeostasis has been scarcely investigated. Despite a recent increased interest in the field, many fundamental issues remain indeterminate. The main objective of this study was to increase the basic knowledge on the role of H2S in bone through in vitro and in vivo studies and develop novel therapeutic strategies for bone diseases. Ex vivo experiments revealed that H2S-generating enzymes (Cystathionine-β-synthase, CBS; Cystathionine-γ-lyase, CSE) are expressed in human bone tissues and human bone-derived cells. In vitro experiments evidenced that CBS and CSE expression is a distinctive feature of the transition of mesenchymal stromal cells (h-MSCs) toward mature osteoblast. Furthermore, loss of function experiments on CBS and CSE during osteogenic differentiation of h-MSCs revealed an impaired mineralization ability. In vivo experiments in mice highlighted the role of CBS, CSE and H2S in the maintenance of bone homeostasis and CBS, CSE and H2S were found to be depleted in post-menopausal osteoporosis. Furthermore, our in vitro and in vivo data validated the use of H2S-donors as novel potential candidates for the treatment of bone pathologies. In particular H2S administration prevented and reversed ovariectomy-induced bone loss in mice. Based on these evidences, we firstly developed an H2S-releasing hybrid drug (DM-22) by modifying a clinically relevant anti-resorptive drug in order to improve the therapy of bone loss. DM-22 displayed improved biological properties compared to the parent drug; in particular, it increased the osteogenic differentiation ability of h-MSCs. Secondly, we developed an H2S-releasing scaffold to improve bone regeneration which was permissive for h-MSCs colonization and supported their osteogenic differentiation.
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Gambari, Laura <1985>. "Hydrogen Sulfide (H2S) Based Therapeutics for Bone Diseases: Translating Physiology to Treatments." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7535/.
Повний текст джерелаАнотація:
Much progress has been made in the past decade in elucidating the physiological, pathophysiological and pharmacological role of Hydrogen Sulphide (H2S). Recently a function of H2S virtually in every tissue of the human organism has emerged. However, the H2S-mediated regulation of bone homeostasis has been scarcely investigated. Despite a recent increased interest in the field, many fundamental issues remain indeterminate. The main objective of this study was to increase the basic knowledge on the role of H2S in bone through in vitro and in vivo studies and develop novel therapeutic strategies for bone diseases. Ex vivo experiments revealed that H2S-generating enzymes (Cystathionine-β-synthase, CBS; Cystathionine-γ-lyase, CSE) are expressed in human bone tissues and human bone-derived cells. In vitro experiments evidenced that CBS and CSE expression is a distinctive feature of the transition of mesenchymal stromal cells (h-MSCs) toward mature osteoblast. Furthermore, loss of function experiments on CBS and CSE during osteogenic differentiation of h-MSCs revealed an impaired mineralization ability. In vivo experiments in mice highlighted the role of CBS, CSE and H2S in the maintenance of bone homeostasis and CBS, CSE and H2S were found to be depleted in post-menopausal osteoporosis. Furthermore, our in vitro and in vivo data validated the use of H2S-donors as novel potential candidates for the treatment of bone pathologies. In particular H2S administration prevented and reversed ovariectomy-induced bone loss in mice. Based on these evidences, we firstly developed an H2S-releasing hybrid drug (DM-22) by modifying a clinically relevant anti-resorptive drug in order to improve the therapy of bone loss. DM-22 displayed improved biological properties compared to the parent drug; in particular, it increased the osteogenic differentiation ability of h-MSCs. Secondly, we developed an H2S-releasing scaffold to improve bone regeneration which was permissive for h-MSCs colonization and supported their osteogenic differentiation.
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Luo, Xiang. "Hydrogen production from catalytic steam reforming of bio-oil over nano NixMgyO solid solution." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37439/.
Повний текст джерелаАнотація:
Hydrogen production from bio-resource is a promising option. In order to economically and practically derive hydrogen from biomass on a sustainable scale, novel catalysts are needed to be developed with properties of effective and inexpensive. In this study, initial works include the preparation of Ni/MgO catalysts via different methods including co-precipitation, hydrothermal treatment and wet-impregnation. These catalysts formed solid solutions after calcination at 600 ℃. It was found that hydrothermal treatment increased the specific surface area of the catalyst from 49.7 m2/g to 79.8 m2/g. In addition, the total pore volume and t-plot micropore volume of the hydrothermally treated Ni/MgO (NixMgyO-hydro) increased by a great extent. In the 20 h methanol steam reforming tests, NixMgyO solid solutions prepared via different methods were examined for their catalytic performance, stability and resistance to carbon deposition. Amongst all the catalysts tested, the NixMgyO-hydro catalyst exhibited the highest conversion rate of 97.4mol% with no carbon deposition. This was particularly true when the steam-to-carbon ratio (S/C) was 3. When S/C was 1, similarly, the NixMgyO-hydro showed the highest performance and the lowest amount of carbon deposition. Characterizations of the spent NixMgyO-hydro revealed that it had very low portion of highly ordered carbon on its surface. It is attributed to the rapid removal of atomic carbon, which led to the prevention of carbon accumulation and subsequent transformation into highly ordered structure. The carbon removal mechanism was confirmed by CO2-TPD analysis. The strong basic sites on the NixMgyO-hydro surface enhanced the reaction between deposited carbon and adsorbed CO2. In addition, the catalytic activity of NixMgyO-hydro catalyst was compared with the Ni/γ-Al2O3 catalyst and several other commercial catalysts. Its outstanding performance in steam reforming of methanol was further verified. Although the NixMgyO-hydro catalyst showed good performance in the steam reforming of methanol, it was not the case for ethanol reforming. The NixMgyO-hydro catalyst showed low hydrogen yield and serious carbon deposition during ethanol steam reforming. The low hydrogen yield was caused by the suppression of water-gas shift reaction (WGSR) at high temperatures, whilst the carbon fouling was due to the existence of C-C bonds in ethanol and high selective conversion towards ethylene. Therefore, the modification of the NixMgyO-hydro catalyst was carried out to overcome these drawbacks. Various elements, i.e., Ce, La and Co, were as catalytic promoters and individually added to the NixMgyO-hydro catalyst. Most of the modified catalysts exhibited much higher hydrogen yield at 700 ℃ due to the enhancement of WGSR. Some catalysts, such as Ce- and Co-modified catalysts, showed significant increase in hydrogen yields, which were higher than 80mol% after 30 h of reaction. It is worth mentioning that the La-modified catalysts promoted the hydrogen yield to 53mol% even at low temperature condition (500 ℃), whilst it was only 12.5mol% with the unmodified catalyst at the same temperature. The reason for this was due to the lack of suitable acid sites on La surface, which led to the accelerated formation of acetaldehyde. The advantage of acetaldehyde is it could be decomposed at very low temperature. The formation of carbon on Ce- and La-modified catalysts was also suppressed. The Ce element showed outstanding oxygen storage and release capability to improve the gasification of carbon deposition. Similarly, La2O3 would form La2O2CO3 species which could achieve carbon removal by offering CO2. Subsequently, the modified catalysts were tested with acetic acid (HAc) and phenol as feedstock, both of which are the most common-seen compounds in bio-oil. The results of these tests, such as catalytic performance and anti-carbon abilities, were consistent with the findings in ethanol steam reforming. Most of the modified catalysts showed very high hydrogen yields above 80mol%, which were only 61.9mol% and 73.7mol% for the unmodified NiMgO catalyst in the steam reforming of HAc and phenol, respectively. The better resistant abilities of the modified catalysts over carbon deposition were also confirmed in the steam reforming of HAc and phenol. In order to determine the performance of the catalysts in steam reforming of actual bio-oil, all of the modified catalysts were evaluated based on their performance in the reforming of major model compounds of bio-oil. Three hydrothermally treated catalysts, i.e., 1%Ce/NiMgO, 2%La/NiMgO and 2%Co/NiMgO, were selected and tested. All three catalysts showed carbon conversions above 90mol% and hydrogen yield in excess of 70mol% after 100 h test. The amounts of carbon deposition on these catalysts were also within an acceptable range. It can therefore be concluded that the NixMgyO solid solution with proper modification, i.e. addition of suitable promoter, could be developed as a promising catalyst for hydrogen production via the steam reforming of bio-oil.
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Wang, Meng. "Steam reforming of model compounds of bio-oil with and without CO₂ sorbent." HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/212.
Повний текст джерелаАнотація:
Hydrogen as a clean energy carrier has drawn great attention. Production of H2 from sustainable bio-oil is considered an alternative for conventional fossil fuel based energy system, since the overall process of bio-oil converting to H2 ideally is carbon-neutral and hence environmental friendly. This study focuses on developing an adequate catalyst for bio-oil steam reforming to produce H2. Ruthenium and/ or nickel based catalysts supported on alumina, ceria-alumina or ceria-silica were synthesized by sol-gel method or incipient wetness impregnation and characterized using BET Surface area analysis, Powder X-Ray diffraction (XRD), Temperature Programmed Reduction (TPR) and Scanning Electron Microscopy (SEM). Steam reforming of selected model compounds, n-propanol, glycerol and acetic acid, was investigated in a fixed bed tubular flow reactor over the prepared catalysts at 450 or 500 °C. The effects of support nature, preparation method, catalyst composition and reaction temperature on the steam reforming activity and stability of catalysts were studied. Catalysts showing better performance in terms of reactant conversion and H2 yield were selected for investigating the steam reforming of an acetic acid/glycerol aqueous mixture, consisting of acetic acid and glycerol with a weight ratio of 3/7 similar to a bio-oil generated from fast pyrolysis of cellulose. The steam-to-carbon ratio (S/C) and the flow rate of feed were constant at 4 and 0.1 ml/min, respectively. The effluent gas was monitored by GC/TCD and the evolution of carbon conversion and product gas distribution as a function of time was studied. Among all catalysts investigated, the one with nominal composition A10C10N1Rnc showed the best performance in steam reforming at 500 °C as indicated by higher and more stable H2 yields achieved regardless the reactant used. In order to investigate the sorption-enhanced steam reforming, three CaO-based CO2 absorbents were synthesized: two derived from calcium acetate with or without MgO support, noted as CAM and CA, respectively, and the other MgO-supported one derived from calcium d-gluconate, denoted as CGM. Results from the 15-carbonation/regeneration-cycle test suggested that the MgO-containing absorbent CAM has the highest CaO molar conversion and stable CO2 absorption capacity. Though significantly higher CO2 absorption capacity was shown from absorbent CA in the first one cycle, CA absorbent soon lost most of the CO2 absorption capacity due to severe sintering. In addition, the CO2 absorption capacity of absorbent CGM might be underestimated due to insufficient carbonation time. The A10C10N1Rnc catalyst and the CAM absorbent were applied in the steam reforming of acetic acid/glycerol mixture at 500°C. However, no significant improvement can be observed in the presence of absorbent CAM
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Wollbrink, Alexander [Verfasser]. "Hydrogen-selective porous carbon-based membranes for catalytic steam reforming of bio-ethanol / Alexander Wollbrink." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2021. http://d-nb.info/123055064X/34.
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Ayad, Massinissa. "Réactivité biomimétique du dioxygène au sein de complexes du fer et du cuivre en vue de l’activation des liaisons C-H." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0054.
Повний текст джерелаАнотація:
L’oxydation catalytique des liaisons C-H, en condition aérobie est l’une des réactions « phare » de la chimie, aussi bien d’un point de vue fondamental qu’industriel. Le principal défi consiste en l’utilisation de l’oxygène moléculaire comme oxydant « vert » pour l’activation de ces liaisons C-H. De nombreuses métalloprotéines, telles que les mono-oxygénases (Fe, Cu), sont capables de réaliser ces réactions dans des conditions douces. Une stratégie actuelle consiste à développer des systèmes synthétiques capables de reproduire de manière efficace les propriétés catalytiques de ces enzymes. L’objectif principal de nos travaux a été de synthétiser et de caractériser des modèles de mono-oxygénases solubles (sMMO) et membranaires (pMMO). Deux approches ont été développées. La première a consisté à élaborer des ligands ditopiques dissymétriques, dont les deux sites de coordination tris-(2-pyridymethyl)amine “TPA” et pyridinedicarboxamide “PydCA”, sont enclavés dans un seul macrocycle afin de favoriser une distance intermétallique optimale. La seconde stratégie est basée sur la synthèse de ligands ditopiques où les motifs coordinants, tetraazacyclotetradecane “cyclam” et dipicolylamine “DPA”, sont séparés par un espaceur de type phényle. Ces deux approches ont conduit à l’obtention et à la caractérisation, à l’état solide (structure aux rayons X) et en solution (spectroscopie, électrochimie), de nombreux complexes mono et dinucléaires du fer, du cuivre et du cobalt. L’étude de la réactivité de certains complexes mononucléaires vis-à-vis des oxydants tels que O2 et H2O2, en l’absence de substrats organiques, a permis d’identifier des espèces métal-oxygène. L’oxydation catalytique de substrats organiques a également été réaliséeCatalytic oxydation of C-H bonds using molecular oxygen as ‘green’ oxidant remains a great challenge from both fundamental and industrial point of views. Many metalloproteins, such as copper end iron-based mono-oxygenases are able to perform these reactions under mild conditions. A current strategy is to develop synthetic complexes which can reproduce the efficiency of such enzymes. The main objective of our work has been to synthesize and characterize new models of soluble (sMMO) and particulate (pMMO) mono-oxygenases. Two approaches have been developed. The first strategy was to synthesize unsymmetrical dinucleating ligands bearing two coordination sites, tris-(2-pyridylmethyl)amine “TPA” and pyridinedicarboxamide “PydCA”, which are embedded in a single macrocycle to favor intermetallic interaction. The second strategy is based on the synthesis of dinucleating ligands where coordinating patterns, tetraazacyclotetradecane “cyclam” and dipicolylamine “DPA”, are separated by a phenyl type spacer. These two approaches have led to the formation and characterization in the solid state (X-ray structure) and in solution (spectroscopy, electrochemistry) of many mononuclear and dinuclear iron, copper and cobalt complexes. The study of the reactivity of some mononuclear complexes towards oxidants such as O2 and H2O2, in absence of organic substrates, has led to the identification of metal-oxygen species. Catalytic oxidation of organic substrates was also conducted
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Nogueira, Francisco Guilherme Esteves. "Catalisadores de Ni promovidos com Mg e Nb para reforma a vapor do ácido acético como molécula modelo do bio-óleo." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-02022015-155946/.
Повний текст джерелаАнотація:
O desenvolvimento de tecnologias para geração de hidrogênio no Brasil tem se tornado um fator relevante, pois se trata de uma fonte de combustível limpa que pode ser obtida a partir de diversas matérias-primas renováveis. Entre essas tecnologias pode-se destacar a reforma a vapor do bio-óleo, proveniente da pirólise da biomassa. O bio-óleo consiste em uma mistura complexa de diversos compostos orgânicos oxigenados tais como: aldeídos, ácidos carboxílicos, cetonas, carboidratos, alcoóis, entre outros, sendo o ácido acético um dos compostos majoritários (∼12-15%), o qual pode ser utilizado como molécula modelo do bio-óleo em reações de reforma a vapor. Entretanto, a reforma a vapor do ácido acético apresenta algumas dificuldades, como a formação de coque na superfície dos catalisadores, o que pode resultar na desativação do mesmo. Dentro deste contexto, este trabalho teve como objetivo desenvolver catalisadores a base de níquel (Ni) promovidos com magnésio (Mg) e nióbio (Nb) suportados em alumina (γ-Al2O3), para aplicação na reforma a vapor do ácido acético, visando minimizar e/ou modificar a estrutura dos depósitos carbonáceos, bem como aumentar a atividade e seletividade para o hidrogênio. Para isso, sintetizaram-se inicialmente três catalisadores com diferentes teores de Ni, (10, 15 e 20%), suportados em alumina, sendo que o catalisador com 15% de Ni em massa foi o que apresentou melhor seletividade e atividade para a reforma a vapor do ácido acético. A partir da melhor carga de Ni, adicionaram-se quatro diferentes teores de Mg e Nb 1,0%; 2,5%; 5,0% e 10% em massa. Entre os catalisadores promovidos com Mg, o catalisador com 5,0% de Mg (15%Ni5%Mg/Al), apresentou uma conversão de 96% para o ácido acético, com seletividade para o hidrogênio em torno de 65% a 600 oC. Além disso, este catalisador apresentou menor taxa de formação de coque e menor tamanho de partícula de Ni0, comparado ao catalisador não promovido (15%Ni/Al), evidenciando que a adição de Mg pode prevenir a sinterização das partículas de Ni. Entre os catalisadores promovidos com Nb, o catalisador 15%Ni2,5%Nb/Al apresentou maior seletividade para o hidrogênio (∼73%) a 600o C comparado aos demais. Apesar de ter apresentado um maior tamanho de partícula Ni0, a adição de Nb aumentou a capacidade de decomposição do metano, proveniente da reação de decomposição e metanação do ácido acético, favorecendo a produção de hidrogênio, além de promover a formação de nanoestruturas de carbono. Assim, a adição de promotores catalíticos como os estudados neste trabalho pode contribuir para o aumento na produção de hidrogênio, seja pela redução nos depósitos carbonáceos ou pela modificação das estruturas de carbono formados na superfície dos materiais.The development of technologies for generating hydrogen in Brazil has become an important factor because it is a source of clean fuel which can be obtained from different renewable raw materials. Among these technologies, the steam reforming of bio-oil from the pyrolysis of biomass can be highlighted. The bio-oil is a complex mixture of different oxygenated organic compounds such as aldehydes, carboxylic acids, ketones, carbohydrates and alcohols with acetic acid being one of the major compounds (∼12-15%), which may be used as a model molecule of bio-oil steam reforming reactions. However, the steam reforming of acetic acid presents some difficulties, such as coke formation on the surface of the catalysts, which may result in its deactivation. Thus, this work aimed to develop catalysts based on nickel (Ni) promoted with magnesium (Mg) and niobia (Nb) supported on alumina (γ-Al2O3), for application in steam reforming of acetic acid in order to minimize the formation of carbonaceous residues, as well as increase the activity and selectivity for hydrogen. For this purpose, initially three catalysts were synthesized with different Ni content, (10, 15 and 20%), and the catalyst with 15% Ni mass showed the best activity and selectivity for the steam reforming of acid acetic acid. From the best Ni loading, was added four different concentrations of Mg and Nb, 1%; 2.5%; 5% and 10% by weight. Among the catalysts promoted with Mg, the catalyst with 5% Mg (15% Ni5% Mg/Al) at a temperature of 600 °C, showed a 96% conversion of acetic acid, with selectivity to hydrogen of around 65 %. In addition, this catalyst showed lower rate of coke formation and lower Ni particle size compared to the non-promoted catalyst (15% Ni/Al), showing that the addition of Mg can prevent sintering of Ni particles. Among the catalysts promoted with Nb, the catalyst 15% Ni 2, 5% Nb/Al showed higher selectivity to hydrogen (∼73%) at 600 °C compared to the others. Despite having a larger particle size, the addition of Nb increased the capacity of decomposition of methane from of the decomposition reaction and methanation of acetic acid favoring the production of hydrogen and promoted the formation of nanostructures. Thus, the addition of catalytic promoters can contribute to the increase in hydrogen production, either by a reduction in carbonaceous deposits or the modification of structures formed on the surface of the materials.
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Coutard, Nathan. "Optimisation et intégration d'anodes bio-inspirées dans une pile à combustible sans platine." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAV021/document.
Повний текст джерелаАнотація:
L'utilisation de nouveaux vecteurs énergétiques comme alternative aux combustibles fossiles et nucléaires est nécessaire pour la transition vers les énergies renouvelables. Ces sources d'énergie intermittentes peuvent être stockées dans des carburants, tels que le dihydrogène qui se distingue par sa densité énergétique. L'oxydation contrôlée de H2 peut être effectuée dans des piles à combustible, qui oxydent l'hydrogène à l'anode et réduisent l'oxygène à la cathode pour former de l'eau et de la chaleur comme seuls produits de la réaction. Ces technologies, matures, emploient des métaux du groupe du platine comme catalyseurs à l'anode et à la cathode. Cependant, alors que les demandes énergétiques mondiales ne cessent d'augmenter, ces ressources limitées ne seront pas suffisantes pour une adoption mondiale de l'hydrogène comme vecteur énergétique. Dans ce travail, des matériaux contenant des catalyseurs bio-inspirés, sans métaux nobles pour l'oxydation de H2 sont optimisés et intégrés dans des piles à combustible fonctionnelles. Leur comportement dans des conditions technologiques est étudié et comparé à celui de l'état de l'art des catalyseurs au platine. Les matériaux les plus performants sont caractérisés en détail par diverses techniques, donnant des pistes pour une optimisation future ainsi qu'un aperçu de ce que requièrent les tests de performance de nouveaux matériaux catalytiquesThe use of new energy vectors as alternatives to the fossil and nuclear fuels is necessary for the transition to renewable energies. These intermittent energy sources can be stored in fuels, such as hydrogen gas which stands out for its energy density and participation in the virtuous water splitting cycle. Controlled H2 oxidation can be done in so-called fuel cells, which oxidize hydrogen at the anode and reduce oxygen at the cathode to form water and heat as the sole products of the reaction. Those mature technologies employ platinum group metals as catalysts at both the anode and cathode. However, as worldwide energy demands keep increasing, these limited resources will not be sufficient for a worldwide adoption of H2 as an energy vector. In this work, materials containing noble metal free, bio inspired catalysts for H2 oxidation are optimized and integrated in functional fuel cells. Their behaviour in technologically-relevant conditions is studied and compared to that of state of the art platinum catalysts. The best performing materials are thoroughly characterized with various techniques including advanced electrochemistry, yielding leads for further optimization as well as insight on the benchmarking of novel catalytic materials
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Hernandez-Gonzalez, Sergio Manuel. "Non-Catalytic Production of Hydrogen via Reforming of Diesel, Hexadecane and Bio-Diesel for Nitrogen Oxides Remediation." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228317376.
Повний текст джерела
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Seelam, P. K. (Prem Kumar). "Hydrogen production by steam reforming of bio-alcohols:the use of conventional and membrane-assisted catalytic reactors." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526202778.
Повний текст джерелаАнотація:
Abstract The energy consumption around the globe is on the rise due to the exponential population growth and urbanization. There is a need for alternative and non-conventional energy sources, which are CO2-neutral, and a need to produce less or no environmental pollutants and to have high energy efficiency. One of the alternative approaches is hydrogen economy with the fuel cell (FC) technology which is forecasted to lead to a sustainable society. Hydrogen (H2) is recognized as a potential fuel and clean energy carrier being at the same time a carbon-free element. Moreover, H2 is utilized in many processes in chemical, food, metallurgical, and pharmaceutical industry and it is also a valuable chemical in many reactions (e.g. refineries). Non-renewable resources have been the major feedstock for H2 production for many years. At present, ~50% of H2 is produced via catalytic steam reforming of natural gas followed by various down-stream purification steps to produce ~99.99% H2, the process being highly energy intensive. Henceforth, bio-fuels like biomass derived alcohols (e.g. bio-ethanol and bio-glycerol), can be viable raw materials for the H2 production. In a membrane based reactor, the reaction and selective separation of H2 occur simultaneously in one unit, thus improving the overall reactor efficiency. The main motivation of this work is to produce H2 more efficiently and in an environmentally friendly way from bio-alcohols with a high H2 selectivity, purity and yield. In this thesis, the work was divided into two research areas, the first being the catalytic studies using metal decorated carbon nanotube (CNT) based catalysts in steam reforming of ethanol (SRE) at low temperatures (<450 °C). The second part was the study of steam reforming (SR) and the water-gas-shift (WGS) reactions in a membrane reactor (MR) using dense and composite Pd-based membranes to produce high purity H2. CNTs were found to be promising support materials for the low temperature reforming compared to conventional catalyst supports, e.g. Al2O3. The metal/metal oxide decorated CNTs presented active particles with narrow size distribution and small size (~2–5 nm). The ZnO promoted Ni/CNT based catalysts showed the highest H2 selectivity of ~76% with very low CO selectivity <1%. Ethanol was shown to be a more suitable and viable source for H2 than glycerol. The dense Pd-Ag membrane had higher selectivity but a lower permeating flux than the composite membrane. The MR performance is also dependent on the active catalyst materials and thus, both the catalyst and membrane play an important role. Overall, the membrane–assisted reformer outperforms the conventional reformer and it is a potential technology in pure H2 production. The high purity of H2 gas with a CO-free reformate for fuel cell applications can be gained using the MR systemTiivistelmä Maailman energiankulutus on kasvussa räjähdysmäisen väestönkasvun ja voimakkaan kaupungistumisen myötä. Tällä hetkellä energian tuottamisen aiheuttamat ympäristöongelmat ja taloudellinen epävarmuus ovat seikkoja, joiden ratkaisemiseksi tarvitaan vaihtoehtoisia ja ei-perinteisiä energialähteitä, joilla on korkea energiasisältö ja jotka tuottavat vähän hiilidioksidipäästöjä. Eräs vaihtoehtoisista lähestymistavoista on vetytalous yhdistettynä polttokennotekniikkaan, minkä on esitetty helpottavan siirtymistä kestävään yhteiskuntaan. Vety on puhdas ja hiilivapaa polttoaine ja energian kantaja. Lisäksi vetyä käytetään monissa prosesseissa kemian-, elintarvike-, metalli- ja lääketeollisuudessa ja se on arvokas kemikaali monissa prosesseissa (mm. öljynjalostamoissa). Uusiutumattomat luonnonvarat ovat olleet tähän saakka merkittävin vedyn tuotannon raaka-aine. Tällä hetkellä noin 50 % vedystä tuotetaan maakaasun katalyyttisellä höyryreformoinilla. Puhtaan (yli 99,99 %) vedyn tuotanto vaatii kuitenkin useita puhdistusvaiheita, jotka ovat erittäin energiaintensiivisiä. Integroimalla reaktio- ja puhdistusvaihe samaan yksikköön (membraanireaktori) saavutetaan huomattavia kustannussäästöjä. Biopolttoaineet, kuten biomassapohjaiset alkoholit (bioetanoli ja bioglyseroli), ovat vaihtoehtoisia lähtöaineita vedyn valmistuksessa. Tämän työn tavoitteena on tuottaa vetyä bioalkoholeista tehokkaasti (korkea selektiivisyys ja saanto) ja ympäristöystävällisesti. Tutkimus on jaettu kahteen osaan, joista ensimmäisessä tutkittiin etanolin katalyyttistä höyryreformointia matalissa lämpötiloissa (<450 °C) hyödyntämällä metallipinnoitettuja hiilinanoputkia. Työn toisessa osassa höyryreformointia ja vesikaasun siirtoreaktioa tutkittiin membraanireaktorissa käyttämällä vedyn tuotantoon tiheitä palladiumpohjaisia kalvoja sekä huokoisia palladiumkomposiittikalvoja. Hiilinanoputket (CNT) havaittiin lupaaviksi katalyyttien tukimateriaaleiksi verrattuna tavanomaisesti valmistettuihin tukiaineisiin, kuten Al2O3. CNT-tukiaineelle pinnoitetuilla aktiivisilla aineilla (metalli-/metallioksidit) todettiin olevan pieni partikkelikoko (~2–5 nm) ja kapea partikkelikokojakauma. Sinkkioksidin (ZnO) lisäyksellä Ni/CNT-katalyytteihin saavutettiin korkea vetyselektiivisyys (~76 %) ja erittäin alhainen hiilimoksidiselektiivisyys (<1 %). Etanolin todettiin olevan parempi vedyn raaka-aine kuin glyserolin. Tiheillä Pd-Ag-kalvoilla havaittiin olevan vedyn suhteen korkeampi selektiivisyys mutta matalampi vuo verrattuna palladiumkomposiittikalvoihin. Membraanireaktorin suorituskyky oli riippuvainen myös katalyytin aktiivisuudesta, joten sekä kalvolla että katalyyttimateriaalilla oli merkittävä rooli kyseisessä reaktorirakenteessa. Yhteenvetona voidaan todeta, että membraanierotukseen perustuva reformointiyksikkö on huomattavasti perinteistä reformeriyksikköä suorituskykyisempi mahdollistaen tehokkaan teknologian puhtaan vedyn tuottamiseksi. Membraanitekniikalla tuotettua puhdasta vetyä voidaan hyödyntää mm. polttokennojen polttoaineena
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Caumes, Xavier. "Hydrogen-bonded supramolecular polymers as dynamic scaffolds for catalysis." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066554/document.
Повний текст джерелаАнотація:
Des polymères supramoléculaires liés par liaisons hydrogènes basés sur des motifs associatifs de type benzène-1,3,5-tricarboxamide (BTA) et bis-urée ont été étudiés comme support dynamique pour la catalyse. Les propriétés catalytiques d'un lot de ligands, comprenant une série de onze nouveaux ligands bis-urées, et des co-monomères complémentaires ont été étudiés pour diverses réactions catalysées par des métaux. Des copolymères formés par mélange de monomères achiraux fonctionnalisés par des phosphines (les ligands) et des additifs sans fonctions phosphines (les co-monomères) ont été étudiés comme supports pour la catalyse asymétrique. L'objectif était de transférer, amplifier et changer la chiralité supramoléculaire du support polymère vers le centre métallique intrinsèquement achiral localisé à sa périphérie. Des mélanges de BTA ont été utilisés aves succès dans deux différentes catalyses asymétriques avec jusqu'à 85% ou 80% d'e.e. pour respectivement l'hydrogénation de l'itaconate de diméthyle catalysée par le rhodium et l'hydrosilylation de la 4'-nitro-acétophénone catalysée par le cuivre. Les centres catalytiques de rhodium et de cuivre supportés par les BTA montrent de fortes propriétés d'amplification de chiralité : i) pour la catalyse au rhodium, la quantité nécessaire de co-monomère chiral peut être réduite jusqu'à un quart de celle du ligand sans détérioration de l'énantioséléctivité de la réaction et ii) la chiralité du catalyseur au cuivre peut être changée pendant le déroulement de la réaction. Une autre plateforme, basée sur des mélanges de monomères bis-urée, a aussi été étudiée dans plusieurs réactions asymétriques catalysées par des métaux mais de l’énantioséléctivité n’a été obtenue que pour l’hydrosilylation de la 4’-nitro-acétophénone catalysé par le cuivre (22% e.e.). Dans le contexte de l’organocatalyse, la possibilité de modifier l’activité d’un centre catalytique de type thiourée en contrôlant son auto-assemblage a aussi été étudié. Au bilan, nos études montrent clairement les propriétés innovantes de catalyseurs supportés par des polymères supramoléculaires liés par liaisons hydrogèneHydrogen-bonded supramolecular polymers based on benzene-1,3,5-tricarboxamide (BTA) and bis-urea recognition units were investigated as dynamic scaffolds for catalysis. The catalytic properties of a full set of ligands, including a series of eleven new bis-urea ligands, and complementary co-monomers have been investigated in various metal-catalyzed reactions. Co-polymers formed by mixing an achiral phosphine-functionalized monomer (the ligand) and a chiral phosphine-free additive (the co-monomer) were investigated as scaffolds for asymmetric catalysis. The aim was to transfer, amplify and switch the supramolecular chirality of the polymer scaffold to intrinsically achiral metal centres located at its periphery. BTA mixtures have been successfully applied in two different asymmetric reactions providing up to 85% and 80% e.e. in the rhodium-catalysed hydrogenation of dimethylitaconate and in the copper-catalysed hydrosilylation of 4’-nitro-acetophenone respectively. The BTA scaffold supporting the catalytic rhodium and copper centres display strong chirality amplification properties: i) for the rhodium catalysis, the amount of chiral co-monomer can be decreased down to one-fourth of that of the ligand without deteriorating the enantioselectivity of the reaction and ii) the chirality of the copper catalyst can be switched during the course of the catalytic reaction. In the case of the bis-urea platform, mixtures of monomers have been investigated in several asymmetric metal-catalysed reactions but selectivity was obtained only for the copper-catalyzed hydrosilylation of 4’-nitro-acetophenone (22% e.e). We also tested the use of supramolecular polymers in the context of organocatalysis: the possibility of tuning the activity of a thiourea catalytic centre by controlling its self-assembly behaviour was investigated. Overall, our studies clearly reveal the innovative properties of catalysts supported by hydrogen-bonded supramolecular polymers
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Zhang, Keren. "Bio-inspired Design and Self-Assembly of Nucleobase- and Ion-Containing Polymers." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/73986.
Повний текст джерелаАнотація:
Bio-inspired monomers functionalized with nucleobase or ionic group allowed synthesis of supramolecular polymers using free radical polymerization and controlled radical polymerization techniques. Comprehensive investigations for the structure-property-morphology relationships of these supramolecular polymers elucidated the effect of noncovalent interactions on polymer physical properties and self-assembly behaviors.
Reverse addition-fragmentation chain transfer (RAFT) polymerization afforded acrylic ABC and ABA triblock copolymers with nucleobase-functionalized external blocks and a low-Tg central block. The hard-soft-hard triblock polymer architecture drove microphase-separation into a physically crosslinked hard phase in a low Tg matrix. Hydrogen bonding in the hard phase enhanced the mechanical strength and maintained processability of microphase-separated copolymers for thermoplastics and elastomers. A thermodynamically favored one-to-one stoichiometry of adenine and thymine yielded the optimal thermomechanical performance. Intermolecular hydrogen bonding of two thymine units and one adenine unit allowed the formation of base triplets and directed self-assembly of ABC triblock copolymers into remarkably well-defined lamellae with long-range ordering. Acetyl protected cytosine and guanine-containing random copolymers exhibited tunable cohesive strength and peel strength as pressure sensitive adhesives. Post-functionalization converted unprotected cytosine pendent groups in acrylic random copolymers to ureido-cytosine units that formed quadruple self-hydrogen bonding. Ureido-cytosine containing random copolymers self-assembled into nano-fibrillar hard domains in a soft acrylic matrix, and exhibited enhanced cohesive strength, wide service temperature window, and low moisture uptake as soft adhesives.
A library of styrenic DABCO salt-containing monomers allowed the synthesis of random ionomers with two quaternized nitrogen cations on each ionic pendant group. Thermomechanical, morphological, and rheological analyses revealed that doubly-charged DABCO salts formed stronger ionic association and promoted more well-defined microphase-separation compared to singly-charged analogs with the same charge density. Bulkier counterions led to enhanced thermal stability, increased phase-mixing, and reduced water uptake for DABCO salt-containing copolymers, while alkyl substituent lengths only significantly affected water uptake of DABCO salt-containing copolymers. Step growth polymerization of plant oil-based AB monomer and diamines enabled the synthesis of unprecedented isocyanate-free poly(amide hydroxyurethane)s, the first examples of film-forming, linear isocyanate-free polyurethanes with mechanical integrity and processability. Successful electrospinning of segmented PAHUs afforded randomly orientated, semicrystalline fibers that formed stretchable, free-standing fiber mats with superior cell adhesion and biocompatibility.Ph. D.
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Cyranka, Beatriz. "Otimização do processo de descontaminação no sistema isolador de Bio-Manguinhos." Instituto de Tecnologia em Imunobiológicos, 2011. https://www.arca.fiocruz.br/handle/icict/5910.
Повний текст джерелаАнотація:
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Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil.
Novas tecnologias, como o sistema isolador para ensaios de esterilidade vieram a contribuir com a incorporação de um melhor desempenho destes ensaios no controle de qualidade das indústrias farmacêuticas.Este trabalho teve como objetivo a verificação do processo de biodescontaminação dentro do sistema isolador de Bio-Manguinhos, utilizado como agente esterilizante o gás de peróxido de hidrogênio. Foram utilizadas como biocarga para redução de contaminação microbiológica três concentrações dos microrganismos, Candida albicansATCC 10231, Clostridium sporogenesATCC 11437 eMicrococcus luteusATCC 9341, impregnadas em discos de filtro de celulose. Os estudos de cinética de crescimento dos microrganismos foram realizados para um melhor entendimento do seumetabolismo, bem como aspectos gerais de crescimento que contribuíram para ressaltar que a Candida albicans inicia sua fase exponencial de crescimento na segunda hora do cultivo e finaliza esta etapa na sexta hora do cultivo, com produção máxima de células viáveis, fato observado também no microrganismo Micrococccus luteus. Para o cultivo doClostridium sporogenes o crescimento foi mais lento com uma curva de crescimento com 60 horas de cultivo total. A produção de maior número de células para o Clostridiumfoi alcançada na vigésima quarta hora de cultivo, assim como a maior produção de esporos. Foi estabelecida, ao longo da curva de crescimento, a relação entre densidade ótica e número de células viáveis, relação essa importante para o estabelecimento das condições do estudo em relação à biocarga empregada de cada microrganismo no momento do desafio no sistema isolador. A capacidade de descontaminação avaliada dentro do sistema isolador com o biocida peróxido de hidrogênio revelou o tempo de exposição ao gás de 10 minutos, como resultado final satisfatório apresentando redução total da carga microbiana com destruição total das células viáveis, assim como as formas esporuladas do Clostridium sporogenes. Desta forma conclui-se que o peróxido de hidrogênioé um biocida de eficácia comprovada, nas variáveis deste estudo e o processode descontaminação no sistema isolador de Bio-Manguinhos é compatível comsua atividade finalística na produção de insumos para a saúde.
New technologies such as isolator system for sterility tests came to help with the incorporation of a better performance of these kinds of tests in quality control of pharmaceutical companies. This study aimed to verify the decontamination process within the system isolator of Bio-Manguinhos, usinghydrogen peroxide gas as a sterilizing agent. Three concentrations of microorganisms were used as bioburden for the microbiological contamination reduction, Candida albicansATCC 10231, Clostridium sporogenesATCC 11437 and Micrococcus luteusATCC 9341, impregnated in cellulose filter discs. Studies of growth kinetics of microorganisms were carried out to a better understanding of theirmetabolism, as well as general aspects of growth that contributed to emphasize that the Candida albicansbegins its exponential growth phase in the second hour of cultivation and this step ends at the sixth hour cultivation, with maximum yield of viable cells, this was also observed in the Micrococcus luteusmicroorganism. For the Clostridium sporogenescultivation, growth was slower with a 60 hours growth curve of total culture. The production of more cells for Clostridiumwas achieved in the twenty-fourth hour of cultivation, as well as the maximum spores production. It was established along the growth curve the relationship between optical density and numberof viable cells, this relationship was important to establish the conditions of the study related to the bioburden of each microorganism used to challenge the isolator system. The decontamination capacity evaluated within the isolator system with the hydrogen peroxide biocide showed that the gas exposure time of 10 minutes wassatisfactory demonstrating total reduction of the microbial load with total destruction of viable cells, as well as the sporulated forms of Clostridium sporogenes. Thus it is concluded that hydrogen peroxide is a proved effective biocide, in the variables of this study and decontamination process in the Bio-Manguinhos insulator system is compatible with its main activity in the production of health supplies.
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Chongcharoentaweesuk, Pasika. "Hydrogen production by Rhodobacter sphaeroides and its analysis by metabolic flux balancing." Thesis, University of Manchester, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603211.
Повний текст джерелаАнотація:
There is a global need for sustainable, renewable and clean energy sources. Microbial production of hydrogen from renewable carbon sources, biorefinery compounds such as succinic acid or from food and drinks industry waste meets all these criteria. Although it has been studied for several decades, there is still no large scale bio-hydrogen production because the rate and yield of hydrogen production are not high enough to render the process economical. The dependency of biological hydrogen production of incipient light energy is also an important factor affecting economics. In order to improve the prospects of biohydrogen as a renewable and sustainable energy alternative, the genetic and process engineering approaches should be helped and targeted by metabolic engineering tools such as metabolic flux balance analysis. The overall aim of this research was the development of computational metabolic flux balance analysis for the study of growth and hydrogen production in Rhodobacter sphaeroides. The research reported in this thesis had two approaches; experimental and computational. Batch culture experiments for growth and hydrogen production by Rhodobacter sphaeroides were performed with either malate or succinate as carbon source and with glutamate as the nitrogen source. Other conditions investigated included; i) aerobic and anaerobic growth, ii) light and dark fermentation for growth, and iii) continuous light and cycled light/dark conditions for hydrogen production. The best growth was obtained with succinate under anaerobic photoheterotrophic conditions with the maximum specific growth rate of 0.0467 h– 1, which was accompanied with the maximum specific hydrogen production rate of 1.249 mmol(gDW.h)– 1. The range of the photon flux used was 5.457 - 0.080 mmol(gDW.h)– 1. The metabolic flux balance model involved 218 reactions and 176 metabolites. As expected the optimised specific rates of growth and hydrogen production were higher than those of the experimental values. The best prediction was for hydrogen production on succinate with computed specific hydrogen production rates in the range of 2.314 - 1.322 mmol(gDW.h)– 1. Sensitivity analyses indicated that the specific growth rate was affected by the nitrogen source uptake rate under aerobic dark condition whereas the flux of protein formation had the largest effect on the specific growth rate under anaerobic light condition.
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Wang, Shengdong. "Transition metal-catalyzed reduction reactions adding value to bio-sourced compounds." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S134.
Повний текст джерелаАнотація:
Le travail de recherche concerne l'utilisation de catalyseurs à base de métaux de transition: ruthénium, iridium, cobalt, argent, pour la transformation de substrats bio-sourcés renouvelables en produits à valeur ajoutée pour l'industrie chimique et l'énergie. La transformation par transfert d'hydrogène de l'acide lévulinique en γ-valérolactone a d'abord été développée avec de nouveaux catalyseurs du ruthénium et de l'iridium porteurs d'un ligand dipyridylamine et d'un chlorure en utilisant l'acide formique comme source d'hydrogène. Puis de nouveaux catalyseurs zwitterioniques de type ruthénium et iridium(sulfato)(dipyridylamine) ont été préparés et ils ont conduit aux meilleures productivités observées pour la réduction de l'acide lévulinique en γ-valérolactone par hydrogénation directe. Sur la base des excellentes performances des complexes iridium(sulfato)dans des processus de réduction, l'amination réductrice de l'acide lévulinique et de l'acide o-formylbenzoïque a été réalisée et a permis la synthèse efficace de dérivés de type pyrrolidones, en particulier à partir d'amines primaires encombrées. La déshydrogénation sélective de l'acide formique dans des conditions douces sans additif en milieu aqueux ou en absence de solvant a été développée avec les mêmes types de catalyseurs de l'iridium porteurs du ligand modifié diméthylaminodipyridylamine. Finalement, une méthode d'hydrogénation douce de cétones a été mise en évidence en présence d'un système catalytique à base de nanoparticules d'argent générées in situ. Ce système catalytique permet d'obtenir de bonnes efficacité et sélectivité vis-à-vis d'autre groupement fonctionnelsThis research work deals with the use of catalysts based on transition metals, such as ruthenium, iridium, cobalt, silver for transformations of renewable bio-based substrates to valuable products for applications in chemical industry and energy. The transfer hydrogenation of levulinic acid to γ-valerolactone with novel ruthenium- and iridium(dipyridylamine)chloride complexes using formic acid as hydrogen source was first developed. Then, novel zwitterionic ruthenium and iridium(sulfato)(dipyridylamine) catalysts were prepared, which displayed the highest turnover numbers reported for the reduction of levulinic acid into γ valerolactone using H₂ as hydrogen source. Based on the high catalytic performance of the iridium(sulfato)complexes in reduction processes, the efficient reductive amination of levulinic acid and o formylbenzoic acid, in particular with bulky primary amines, for the synthesis of pyrrolidone derivatives was disclosed. The selective dehydrogenation of formic acid under mild conditions in aqueous media or neat conditions without using an organic additive has been developed using iridium catalysts of the same family equipped with a modified dimethylaminodipyridylamineas ligand. Finally, an unprecedented hydrogenation of ketones in the presence of in situ generated silvernanoparticleswas discovered. High efficacy and functional group selectivity have been achieved in most cases
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MANFREDI, NORBERTO. "Synthesis and investigations of multifunctional organic molecules and materials for applications in the field of renewable energy." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2017. http://hdl.handle.net/10281/153280.
Повний текст джерелаАнотація:
In questo progetto di dottorato, abbiamo studiato nove molecole e materiali per applicazioni in celle solari di terza generazione e produzione fotocatalitica o fotoelettrochimica di H2. La prima parte di questo lavoro è stata focalizzata sullo studio di dispositivi DSSCs andando a studiare nuov fotosensibilizzatori a base organica, alcuni dei quali ottenuti da collaborazioni esterne, e diversi coloranti a base fenotiazinica recanti funzionalizzazioni differenti al fine di modularne proprietà ottiche e fotovoltaiche sia in presenza di elettroliti a base organica sia acquosa. celle solari a perovskiti (PSC) sono state studiate ed è stata sviluppata una procedura di fabbricazione affidabile. Uno studio di fattibilità circa l'integrazione in dispositivi multi-giunzione con mc-Si è stato fatto con successo. Diversi materiali di trasporto di lacune a base di idrazoni sono stati sintetizzati e le loro proprietà ottiche ed elettrochimiche sono state studiati. La mobilità dei portatori di questi nuovi materiali è stata studiata in transistor organici ad effetto di campo e sono stati impiegati in dispositivi PSC.Coloranti fenotiazinici ramificati, sono stati testati come fotosensibilizzatori nella produzione fotocatalitica di H2, in combinazione con un catalizzatore Pt / TiO2. Le proprietà ottiche ed elettrochimiche dei coloranti sono stati studiati, mostrando che un'attenta progettazione dei nuovi coloranti concessi migliorate proprietà ottiche. Nella produzione di H2 oltre 20 h, i nuovi sensibilizzatori rivelato stabilità migliorata dopo tempi di irraggiamento più lunghi e prestazioni migliorate, in termini di velocità di produzione H2 ed efficienze luce-combustibile, che sono stati per la prima volta associate ad una maggiore stabilità in produzione fotocatalitica H2 e all'assenza di degradazione del colorante.
Colorante fenotiazinico analogo è stato funzionalizzato con una unità di glucosio periferico (PTZ-GLU) per aumentare la sua affinità con l'acqua e migliorare fotogenerazione di H2. Rispetto al corrispondente derivato alchilico, nonché il comune idrofila trietilenico (PTZ-TEG); PTZ-GLU è due volte più efficiente di PTZ-TEG nel fotogenerazione di H2 in termini di gas evoluto e numero di turnover. PTZ-GLU è stato studiato in presenza di co-adsorbenti appositamente progettati a base di glucosio (GLU) per promuovere le interazioni direzionali sulla superficie catalitica semiconduttore e, accesso maggiore attività catalitica. Abbiamo dimostrato che l'uso combinato del colorante a base di glucosio e co-adsorbente prestata maggiore H2 fotocatalitico. Una serie di coloranti a base di carbazolo sono stati sintetizzati e utilizzati come fotosensibilizzatori nella generazione H2 fotocatalitico. Rispetto ai coloranti PTZ più comunemente utilizzati, lo sfruttamento della struttura planare e senza zolfo del carbazolo consentono un trasferimento di carica ligando-metallo (LMCT), aumentando la produzione di H2. Uno studio preliminare su coloranti p-type per la produzione di H2 da fotoelettrochimica è iniziato con risultati interessanti.In this PhD project, we studied molecules and new materials for application in third generation solar cells and photocatalytic or photoelectrochemical production of H2. The first part of this work was focused on the study of DSSCs devices going to investigate new organic-based photosensitizers, some of them obtained from external collaborations, and several phenothiazine based dyes bearing different functionalization to modulate optical and photovoltaic properties either in presence of organic and water based electrolyte. Perovskite solar cells (PSC) have also been studied and a reliable fabrication procedure have been developed. A study of feasibility about integration in multi-junction devices with mc-Si have been done successfully. Several hydrazone-based hole transport materials have been synthesized and their optical and electrochemical properties have been investigated. The mobility of carriers of these new materials have been studied in organic field effect transistor and they have been employed in PSC devices. Dibranched phenothiazine based dyes, were tested as photosensitizers in the photocatalytic production of H2, in combination with a Pt/TiO2 catalyst. The optical and electrochemical properties of the dyes were investigated, showing that careful design of the new dyes afforded enhanced optical properties. In the H2 production over 20 h, the new sensitizers revealed improved stability after longer irradiation times and enhanced performances, in terms of H2 production rates and light-to-fuel efficiencies, which were for the first time associated with enhanced stability under photocatalytic production of H2 and the absence of critical dye degradation. Analogous phenothiazine dye has been functionalized with a peripheral glucose unit (PTZ-GLU) to bust its affinity to water and enhance dye-sensitized photogeneration of H2. Compared to the corresponding alkyl derivative, as well as the common hydrophilic triethylene glycol substitution (PTZ-TEG); PTZ-GLU performed twice more efficient than PTZ-TEG in the photogeneration of H2 in terms of evolved gas and turnover number. PTZ-GLU has been investigated in presence of properly designed glucose-based co-adsorbents (GLU) to promote beneficial directional interactions on the semiconductor catalytic surface and, access enhanced catalytic activity. We have demonstrated that the combined use of the glucose-based dye and co-adsorbent afforded enhanced photocatalytic H2. A series of carbazole-based dyes have been synthesized and used as photosensitizers in the photocatalytic H2 generation. Compared to the more commonly used PTZ dyes, the exploitation of the planar and sulfur-free carbazole scaffold allows a ligand-to-metal charge transfer (LMCT) visible light absorption, busting the H2 production. A preliminary study on p-type dyes for H2 production by photoelectrochemistry has begun with interesting results.
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Chen, Keke. "Roll-to-Roll Manufacturing and Real-Time Characterization of Bio-Functional Polymers." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1548177736839976.
Повний текст джерела
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Tamami, Mana. "Synthesis and characterization of ammonium ionenes containing hydrogen bonding functionalities." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19234.
Повний текст джерелаАнотація:
Ammonium ionenes are polycations that have quaternary nitrogens in their macromolecular backbone and are synthesized via step-growth polymerization technique. They offer interesting coulombic properties, and the synthetic design provides control over charge density. Non-covalent interactions including nucleobase hydrogen bonding and electrostatics were studied in ammonium ionenes. The non-covalent interactions are expected to increase the effective molecular weight of polymeric precursors and induce microphase separation due to intermolecular associations. The influence of non-covalent interactions on structure-property relationships of ammonium ionenes were studied regarding mechanical (tensile, DMA), thermal (DSC, TGA), and morphological (AFM, SAXS) properties. Hydrogen bonding interaction (10-40 kJ/mol) was introduced using DNA nucleobase pairs such as adenine and thymine. Novel adenine and thymine functionalized segmented and non-segmented ammonium ionenes were successfully synthesized using Michael addition chemistry. In non-segmented systems, we investigated the influence of spacer length on homoassociation and heteroassociation of complementary nucleobase-containing ionenes. Based on DSC analyses, complementary non-segmented ionenes made miscible blends. The Tgs of ionene blends with shorter spacer length (4 bonds between the nucleobase and secondary amine in the polymer backbone) followed the Fox equation, which indicated no intermolecular interactions. The longer alkyl spacer (9 bonds between nucleobase and secondary amine in the polymer backbone) provided efficient flexibility for the self-assembly process to occur. Thus, increasing the spacer length from 4-bonds to 9-bonds, the Tgs of the blends deviated from both Fox and Gordon-Taylor equations and demonstrated the presence of hydrogen bonding interactions.
In segmented systems, we investigated the association between nucleobase-containing ionenes and their complementary guest molecules. Job\'s method revealed a 1:1 stoichiometry for the hydrogen-bonded complexes. These association constants for the 1:1 complexes, based on the Benesi-Hildebrand model were 94 and 130 M-1 respectively, which were in agreement with literature values for adenine and thymine nucleobase pairs (10-100 M-1). DSC thermograms confirmed no macrophase separation for 1:1 [ionene-A/T]:[guest molecule] complexes based on the disappearance of the melting peak of the guest molecule. Morphological studies including atomic force microscopy (AFM) demonstrated a reduced degree of microphase separation for the 1:1 complexes due to the disruption of adenine-adenine or thymine-thymine interactions.
Poly(dimethyl siloxane)-based ammonium ionenes having various hard segment contents were synthesized. The charge density or hard segment content was tuned for appropriate application using low molecular weight monomer. The change in hard segment content had a profound effect on thermal, mechanical, rheological, and gas permeability. Microphase separation was confirmed using DSC and DMA in these systems. DMA showed that the rubbery plateau modulus extended to higher temperatures with increasing hard segment content. Tensile analysis demonstrated systematic increase in modulus of PDMS-ionenes with increasing hard segment content. Oxygen transmission rates decreased linearly as the wt% hard segment increased.
Ph. D.
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Caumes, Xavier. "Hydrogen-bonded supramolecular polymers as dynamic scaffolds for catalysis." Electronic Thesis or Diss., Paris 6, 2016. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2016PA066554.pdf.
Повний текст джерелаАнотація:
Des polymères supramoléculaires liés par liaisons hydrogènes basés sur des motifs associatifs de type benzène-1,3,5-tricarboxamide (BTA) et bis-urée ont été étudiés comme support dynamique pour la catalyse. Les propriétés catalytiques d'un lot de ligands, comprenant une série de onze nouveaux ligands bis-urées, et des co-monomères complémentaires ont été étudiés pour diverses réactions catalysées par des métaux. Des copolymères formés par mélange de monomères achiraux fonctionnalisés par des phosphines (les ligands) et des additifs sans fonctions phosphines (les co-monomères) ont été étudiés comme supports pour la catalyse asymétrique. L'objectif était de transférer, amplifier et changer la chiralité supramoléculaire du support polymère vers le centre métallique intrinsèquement achiral localisé à sa périphérie. Des mélanges de BTA ont été utilisés aves succès dans deux différentes catalyses asymétriques avec jusqu'à 85% ou 80% d'e.e. pour respectivement l'hydrogénation de l'itaconate de diméthyle catalysée par le rhodium et l'hydrosilylation de la 4'-nitro-acétophénone catalysée par le cuivre. Les centres catalytiques de rhodium et de cuivre supportés par les BTA montrent de fortes propriétés d'amplification de chiralité : i) pour la catalyse au rhodium, la quantité nécessaire de co-monomère chiral peut être réduite jusqu'à un quart de celle du ligand sans détérioration de l'énantioséléctivité de la réaction et ii) la chiralité du catalyseur au cuivre peut être changée pendant le déroulement de la réaction. Une autre plateforme, basée sur des mélanges de monomères bis-urée, a aussi été étudiée dans plusieurs réactions asymétriques catalysées par des métaux mais de l’énantioséléctivité n’a été obtenue que pour l’hydrosilylation de la 4’-nitro-acétophénone catalysé par le cuivre (22% e.e.). Dans le contexte de l’organocatalyse, la possibilité de modifier l’activité d’un centre catalytique de type thiourée en contrôlant son auto-assemblage a aussi été étudié. Au bilan, nos études montrent clairement les propriétés innovantes de catalyseurs supportés par des polymères supramoléculaires liés par liaisons hydrogèneHydrogen-bonded supramolecular polymers based on benzene-1,3,5-tricarboxamide (BTA) and bis-urea recognition units were investigated as dynamic scaffolds for catalysis. The catalytic properties of a full set of ligands, including a series of eleven new bis-urea ligands, and complementary co-monomers have been investigated in various metal-catalyzed reactions. Co-polymers formed by mixing an achiral phosphine-functionalized monomer (the ligand) and a chiral phosphine-free additive (the co-monomer) were investigated as scaffolds for asymmetric catalysis. The aim was to transfer, amplify and switch the supramolecular chirality of the polymer scaffold to intrinsically achiral metal centres located at its periphery. BTA mixtures have been successfully applied in two different asymmetric reactions providing up to 85% and 80% e.e. in the rhodium-catalysed hydrogenation of dimethylitaconate and in the copper-catalysed hydrosilylation of 4’-nitro-acetophenone respectively. The BTA scaffold supporting the catalytic rhodium and copper centres display strong chirality amplification properties: i) for the rhodium catalysis, the amount of chiral co-monomer can be decreased down to one-fourth of that of the ligand without deteriorating the enantioselectivity of the reaction and ii) the chirality of the copper catalyst can be switched during the course of the catalytic reaction. In the case of the bis-urea platform, mixtures of monomers have been investigated in several asymmetric metal-catalysed reactions but selectivity was obtained only for the copper-catalyzed hydrosilylation of 4’-nitro-acetophenone (22% e.e). We also tested the use of supramolecular polymers in the context of organocatalysis: the possibility of tuning the activity of a thiourea catalytic centre by controlling its self-assembly behaviour was investigated. Overall, our studies clearly reveal the innovative properties of catalysts supported by hydrogen-bonded supramolecular polymers
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Vall-llosera, Gemma. "Synchrotron radiation studies of gas phase molecules : from hydrogen to DNA sugars." Doctoral thesis, KTH, Atom- och molekylfysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4640.
Повний текст джерелаАнотація:
This thesis summarises experimental results on the molecular spectroscopy of gas phase molecules excited by synchrotron radiation in the VUV and soft X-ray regions. We have used three different detection techniques, photon induced fluorescence spectroscopy, photoionisation mass spectroscopy and near edge X-ray absorption fine structure spectroscopy to study molecular deuterium, hydrogen sulphide, ammonia, methanol, pyridine, pyridazine, pyrimidine, pyrazine, s-triazine, and 2-deoxy-D-ribose, the last one also known as the DNA sugar. Out of this variety of techniques and molecules we have shown that: (1) high resolution dispersed fluorescence allows us to identify vibrational and rotational bands in molecular deuterium, as well as to estimate the predissociation probability of the same molecule [paper I]; (2) the main species fluorescing after core excitation of methane, ammonia [paper III], hydrogen sulphide [paper II], pyridine, pyrimidine and s-triazine is H Balmer α, followed by fluorescence from ionised species, molecular bands and Balmer β, γ , δ; (3) the Rydberg enhancement seen in fluorescence measurements of water [Melero et al. PRL 96 (2006) 063003], corroborated later in H2S [paper II], NH3 [paper III] and CH4 [paper III] and postulated as general behaviour for molecules formed by low-Z atoms, is also seen in larger organic cyclic molecules, e.g. azabenzenes; (4) when dissociative ionisation of pyridine, pyridazine, pyrimidine, pyrazine, s-triazine and 2-deoxy-D-ribose occurs, concerted bond rearrangement and nuclear motion takes place as opposed to stepwise dissociation [papers V and VI].QC 20100916
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Assfour, Bassem. "Hydrogen Storage In Nanostructured Materials." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-65858.
Повний текст джерелаАнотація:
Hydrogen is an appealing energy carrier for clean energy use. However, storage of hydrogen is still the main bottleneck for the realization of an energy economy based on hydrogen. Many materials with outstanding properties have been synthesized with the aim to store enough amount of hydrogen under ambient conditions.
Such efforts need guidance from material science, which includes predictive theoretical tools.
Carbon nanotubes were considered as promising candidates for hydrogen storage applications, but later on it was found to be unable to store enough amounts of hydrogen under ambient conditions. New arrangements of carbon nanotubes were constructed and hydrogen sorption properties were investigated using state-of-the-art simulation methods. The simulations indicate outstanding total hydrogen uptake (up to 19.0 wt.% at 77 K and 5.52wt.% at 300 K), which makes these materials excellent candidates for storage applications. This reopens the carbon route to superior materials for a hydrogen-based economy.
Zeolite imidazolate frameworks are subclass of MOFs with an exceptional chemical and thermal stability. The hydrogen adsorption in ZIFs was investigated as a function of network geometry and organic linker exchange. Ab initio calculations performed at the MP2 level to obtain correct interaction energies between hydrogen molecules and the ZIF framework. Subsequently, GCMC simulations are carried out to obtain the hydrogen uptake of ZIFs at different thermodynamic conditions. The best of these materials (ZIF-8) is found to be able to store up to 5 wt.% at 77 K and high pressure.
We expected possible improvement of hydrogen capacity of ZIFs by substituting the metal atom (Zn 2+) in the structure by lighter elements such as B or Li. Therefore, we investigated the energy landscape of LiB(IM)4 polymorphs in detail and analyzed their hydrogen storage capacities. The structure with the fau topology was shown to be one of the best materials for hydrogen storage. Its total hydrogen uptake at 77 K and 100 bar amounts to 7.8 wt.% comparable to the total uptake reported of MOF-177 (10 wt.%), which is a benchmark material for high pressure and low temperature H2 adsorption.
Covalent organic frameworks are new class of nanoporous materials constructed solely from light elements (C, H, B, and O). The number of adsorption sites as well as the strength of adsorption are essential prerequisites for hydrogen storage in porous materials because they determine the storage capacity and the operational conditions. Currently, to the best of our knowledge, no experimental data are available on the position of preferential H2 adsorption sites in COFs. Molecular dynamics simulations were applied to determine the position of preferential hydrogen sites in COFs. Our results demonstrate that H2 molecule adsorbed at low temperature in seven different adsorption sites in COFs. The calculated adsorption energies are about 3 kJ/mol, comparable to that found for MOF systems. The gravimetric uptake for COF-108 reached 4.17 wt.% at room temperature and 100 bar, which makes this class of materials promising for hydrogen storage applications.
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Moreira, Renata. "Estudo da pirólise lenta da casca da castanha de caju." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-07102015-090727/.
Повний текст джерелаАнотація:
A casca da castanha de caju (CCC), um resíduo agrícola da produção de castanha, proveniente da região nordeste do Brasil foi caracterizada e submetida ao processo de pirólise lenta. As propriedades do bio-carrvão, do bio-óleo e dos gases produzidos foram investigados e potenciais aplicações foram propostas. A CCC foi caracterizada pela seguintes técnicas: análise elementar CHNS, umidade total, conteúdo de cinzas, matérias voláteis, poder calorífico superior e por análise termogravimétrica. A análise termogravimétrica sob fluxo de nitrogênio mostrou que a decomposição é dominada pela degradação da hemicelulose e celulose na faixa de 250 a 350oC e pela decomposição da lignina na faixa de 400 a 500oC. Na presença de ar, o perfil de degradação é semelhante, porém observa-se uma maior degradação da lignina. A pirólise lenta da casca da castanha de caju foi realizada em um reator tipo batelada aquecido por chama ar-GLP sob diferentes fluxos (mL min-1) de nitrogênio ou ar. O sólido obtido (bio-carvão), líquido (fase aquosa + bio-óleo) e a fase gás foram quantificados e caracterizados por diferentes técnicas. Os experimentos realizados sob fluxo de nitrogênio apresentaram um rendimento de cerca de 30, 40 e 30% em massa paras as fases sólido, líquida e gás, respectivamente. Sob fluxo de ar ocorreu uma diminuição no rendimento da fase líquida, principalmente na produção de bio-óleo, e um aumento da fase gás. Os bio-carvões produzidos apresentaram elevados teores de carbono, na faixa de 70-75% em massa, poder calorífico na faixa de 25 a 28 MJ kg-1, características de carbono amorfo, sem morfologias definidas e ausência de poros. Os espectros FTIR de bio-óleos produzidos sob fluxo de nitrogênio apresentaram um aumento da intensidade relativa das bandas cerca de 1700 cm-1 (ν C=O) e 1230 cm-1 (ν C-O) em comparação com os produzidos sob fluxo de ar, o que sugere a presença de grandes quantidades de compostos oxigenados de carbono, como aldeídos, cetonas e ácidos carboxílicos. As análises das fases gás mostraram a predominância de CO2 e CO a temperaturas inferiores a 400ºC e a formação preferencial de H2 acima desta temperatura.Cashew nut shell (CNS), an agricultural waste of cashew nut production, from northeast region of Brazil was characterized and slow pyrolyzed. The properties of char, bio-oil and gases products were investigated and potential applications were proposed. CNS was characterized by the following analyses: CHNS, total moisture, ash content, volatile matter, high heating value and thermogravimetric analysis. The thermogravimetric analysis under nitrogen flow showed that the decomposition is dominated by the degradation of hemicellulose and cellulose in the range from 250 to 350oC and the decomposition of lignin in the range of 400 to 500oC. In the presence of air, the degradation profile is similar; however the decomposition of lignin increases. Slow pyrolysis of cashew nut shell was carried out in batch-type reactor heated by a combustion flame (air + GLP) under different nitrogen and air flow rates. The resulting solid (char), liquid (water + bio-oil) and gas phases were characterized and quantified. The experiments performed under nitrogen showed a yield of solid, liquid and gas phases of about 30, 40 and 30wt%, respectively. Under air the yield of liquid phase was reduced, primarily the bio-oil yield; production of the gas phase was, in turn, increased. The produced biochars had high carbon contents in the range of 70-80 wt%, high heating values in the range of 25-28 MJ Kg-1 and characteristics of amorphous carbons without defined morphology and the absence of pores. The FTIR spectra of bio-oils produced under nitrogen flow showed an increase of the relative intensity of the bands around 1700 cm-1 (ν C = O) and 1230 cm-1 (ν C-O) in comparison with those produced under air flow which suggests the presence of large amounts of oxygenated carbon compounds such as aldehydes, ketones and carboxylic acids. The analysis of gas phases showed the predominance of CO2 and CO at temperatures lower than 400oC and the preferential formation of H2 above this temperature.
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Almatouq, Abdullah. "Study of the parameters for optimisation of the design and performance of bio-electrochemical systems for energy/hydrogen generation and resource recovery." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/100405/.
Повний текст джерелаАнотація:
This study focused on the exploration, assessment and experimental investigation of bio-electrochemical systems (BES) for concurrent phosphorus (P) recovery and energy generation/hydrogen (H2) production. The main aim was to study and understand the parameters for optimisation of the design and the performance of BESs for concurrent phosphorus recovery and energy generation/hydrogen production. In total, four dual chamber bio-electrochemical systems (Microbial Fuel Cells (MFCs) and Microbial Electrolysis Cells (MECs)) were used to investigate the impacts of key design and operational conditions on BES performance. P was precipitated successfully as struvite in both MFCs and MECs. The MFCs and MECs achieved a maximum P precipitation efficiency of 90% and 95% with a maximum columbic efficiency of 10% and 51% respectively. The MFCs and MECs achieved an average of 80 % and 70 % COD removal efficiency respectively, which confirms the ability of these systems to be used in wastewater treatment. Deterioration in both reactors occurred due to P precipitation on the cathode surface and the membrane. The three operational parameters (influent COD, cathode aeration flow rate, and external resistance) were found to have significant impacts on MFC performance and P recovery. In addition, applied voltage and influent COD had significant effects on MEC performance and P recovery. Results were supported through statistical analysis and optimisation modelling using full factorial design, central composite design, and response surface methodology. Generally, results have shown that MFCs and MECs have the potential to concurrently recover P, treat wastewater, and generate electricity/produce H2. Further research is needed to enhance the performance of MFCs for energy generation and MECs for H2 production in addition to P recovery and minimising scaling on electrodes. The results of this study increase the understanding of P recovery mechanisms in MFCs and MECs and can contribute to future BES research. Moreover, the results will help in selecting the optimum operational parameters of BESs depending on the applications and process requirements. Applying BESs in wastewater treatment plants will reduce energy consumption and, at the same time, find an alternative source of P.
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Duregotti, Elisa. "Neuronal hydrogen peroxide promotes nerve terminals regeneration at neuromuscular junction." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424296.
Повний текст джерелаАнотація:
The neuromuscular junction (NMJ) is the site of transmission of the electrical impulses from the motor axon terminal to the muscle; the anatomical organization of this highly dynamic system also includes the perisynaptic Schwann cells (PSCs), and therefore the NMJ has to be considered structurally and functionally as a tripartite system. These non-myelinating SCs are intimately associated with the nerve muscle contact and act as dynamic partners at the synapse: they are involved in many physiological functions including the embryonic development and the maintenance of adult NMJs. Moreover, they are able to detect and reciprocally modulate synaptic activity, through the activation of muscarinin and purinergic receptors present on their surface.
In addition, non-traditional roles for PSCs in the recovery after nerve injury are being recognized. Following denervation or reduced synaptic activity, PSCs de-differentiate to an earlier developmental stage, becoming “reactive” PSCs, and start proliferating. These reactive PSCs actively participate in the process of nerve degeneration and regeneration: they undergo changes in their gene expression and acquire macrophagic-like activities, thus contributing to the removal of nerve debris as well as to the recruitment of macrophages, by releasing cytokines and chemokines. Moreover, following nerve terminals degeneration, PSCs at denervated end-plates extend long processes that induce and guide nerve regrowth.
Given the increasing incidence of non cell-autonomous and dying-back axonopathies - such as amyotrophic lateral sclerosis (ALS) and autoimmune neuropathies - which affect predominantly motor axons terminals, it becomes very important to characterize the crosstalk between degenerating nerve terminals and adjacent PSCs at the NMJ; in particular, the identification of molecular mediators involved in PSCs activation and in nerve terminals regeneration would be crucial for the improvement of therapeutic strategies.
This is the general aim of the present thesis and with this purpose in mind, we have adopted an innovative experimental approach, alternative to the traditional cut/crush surgical model employed till now. To confine the nerve damage to the sole motor axon terminal, thus avoiding the involvement of many cell types and inflammatory mediators, we exploited our knowledge on the mechanism of action of two classes of animal presynaptic neurotoxins: α-Ltx, a pore forming toxin of the venom of black widow spiders, and some snake neurotoxins endowed with phospholipase A2 activity called SPANs. Both kinds of neurotoxins induce an acute and highly reproducible motor axon terminal degeneration, which is followed in few days by complete regeneration: thus, this model represents an appropriate and controlled system to dissect the molecular mechanisms underlying de- and re-generation of peripheral nerve terminals, and to define how PSCs contribute to such processes.
We have previously shown that nerve terminals exposed to spider or snake neurotoxins degenerate owing to calcium overload and mitochondrial failure. Here, we found that toxin-treated cultured neurons increase their mitochondrial production of hydrogen peroxide (H2O2), which can easily diffuse across membranes, thus acting as a paracrine signal on neighbouring cellS. Indeed, exposure of cultured SCs to H2O2 leads to ERK phosphorylation and to the activation of downstream pathways. The ERK signalling pathway plays a central role in controlling SCs plasticity during nerve repair in-vivo, but so far the molecular mediators responsible for its activation were unknown: neurons-derived H2O2 represents an ideal candidate for this role.
In support of this hypothesis, we observed that ERK phosphorylation is reduced in intoxicated neurons-SCs co-cultures pre-incubated with catalase - which converts H2O2 to oxygen and water -, indicating that H2O2 produced inside neurons diffuses to reach nearby SCs, contributing to ERK activation in their cytosol. ERK phosphorylation takes place also in PSCs at intoxicated NMJs in-vivo. To confirm the involvement of H2O2 in promoting nerve regeneration, we performed electrophysiological recordings and immunohistochemistry on intoxicated muscles, and we found that co-injection of catalase together with neurotoxins delays nerve regeneration, confirming the prominent role of H2O2 in promoting NMJ recovery. Injection of the MAP kinase inhibitor PD98059 also impairs nerve repair in a way similar to that observed with catalase, supporting the finding that H2O2 enhances nerve terminals regeneration through the activation of ERK pathway in PSCsLa giunzione neuromuscolare (GNM) costituisce il sito di trasmissione di un impulso elettrico dal terminale del motoneurone alla fibra muscolare; l’organizzazione strutturale di questo sistema altamente dinamico è stata ulteriormente complicata dall’aggiunta delle cellule di Schwann perisinaptiche (CSPs), dando origine al concetto di sistema tripartito. Le CSPs sono cellule di Schwann non mielinizzanti strettamente adese alla zona di contatto tra nervo e muscolo; esse partecipano attivamente a molte funzioni fisiologiche della GNM, come il suo sviluppo embrionale ma anche il corretto mantenimento di GNMs adulte. Esse sono inoltre in grado di percepire e modulare l’attività sinaptica, mediante l’attivazione di recettori muscarinici e purinergici presenti sulla loro superficie. Studi più recenti hanno dimostrato che le CSPs sono coinvolte nei processi di recupero che hanno luogo in risposta ad un danno nervoso; in seguito a denervazione o a ridotta attività sinaptica, le CSPs de-differenziano, diventando CSPs “reattive”, ed iniziano a proliferare. Queste CSPs reattive partecipano attivamente ai processi di degenerazione e rigenerazione nervosa: esse subiscono variazioni nella loro espressione genica e acquisiscono attività simil-macrofagiche, contribuendo alla rimozione dei detriti neuronali e reclutando fagociti in seguito al rilascio di citochine e chemochine. Inoltre, in seguito alla degenerazione dei terminali nervosi, le CSPs presenti alle placche motrici denervate estendono lunghi processi citosolici in grado di indurre e guidare la ricrescita neuronale. Considerando la crescente incidenza di malattie neurodegenerative che inizialmente interessano in maniera selettiva i terminali dei motoneuroni – quali la SLA e le neuropatie autoimmuni -, sarebbe senz’altro utile caratterizzare in maniera più approfondita il crosstalk tra terminali nervosi in degenerazione e le adiacenti CSPs. In particolare, l’identificazione di mediatori molecolari coinvolti nell’attivazione delle CSPs e nel processo di rigenerazione nervosa potrebbe rivelarsi cruciale per lo sviluppo di nuovi approcci terapeutici. A tale scopo, abbiamo adottato un approccio sperimentale innovativo, alternativo al cut/crush del nervo sciatico tradizionalmente utilizzato fino ad oggi. Al fine di effettuare un danno localizzato ai soli terminali nervosi, evitando il coinvolgimento di molti tipi cellulari e mediatori dell’infiammazione come accade nel corso della degenerazione Walleriana, abbiamo deciso di sfruttare il meccanismo d’azione di due classi di neurotossine presinaptiche animali: α-Latrotoxin, una tossina formante poro presente nel veleno dei ragni del genere Latrodectus, ed alcune neurotossine di serpente dotate di attività fosfolipasica, denominate SPANs. Entrambi i tipi di neurotossine inducono un’acuta e altamente riproducibile degenerazione dei terminali nervosi dei motoneuroni, seguita entro pochi giorni da una rigenerazione completa: l’azione di tali neurotossine rappresenta quindi un sistema appropriato e controllato per esaminare i meccanismi molecolari alla base della degenerazione e rigenerazione nervosa, come anche il contributo delle CSPs a tali processi. Abbiamo precedentemente dimostrato che i terminali nervosi esposti ad α-Ltx e SPANs deegenerano a causa di un eccessivo influsso di calcio nel citosol, che a sua volta induce un danno mitocondriale. In questo lavoro, abbiamo dimostrato che neuroni primari intossicati aumentano la produzione di H2O2 a livello mitocondriale: il perossido di idrogeno è una molecola stabile e diffusibile attraverso membrane lipidiche, e potrebbe perciò agire come segnale paracrino su cellule adiacenti. Infatti, l’esposizione di cellule di Schwann (CSs) primarie in coltura a basse concentrazioni di H2O2 induce la fosforilazione di ERK, con la conseguente attivazione di pathways a valle. È stato recentemente dimostrato che la via di ERK gioca un ruolo fondamentale nel controllo della plasticità delle CSs durante la rigenerazione nervosa in vivo, ma fino ad oggi i mediatori molecolari responsabili per l’attivazione di tale pathway non sono ancora stati identificati: il perossido di idrogeno prodotto dai neuroni in degenerazione costituisce un buon candidato per tale ruolo. In supporto a tale ipotesi, abbiamo osservato che il livello di fosforilazione di ERK è ridotto in co-colture di neuroni e CSs intossicate e pre-incubate con catalasi, che converte rapidamente il perossido di idrogeno in ossigeno ed acqua: ciò conferma che il perossido di idrogeno prodotto dai neuroni diffonde effettivamente nel mezzo extracellulare fino a raggiungere le vicine CSs, nelle quali induce l’attivazione della via di ERK. Tale attivazione è riscontrata anche nelle CSPs alle GNMs intossicate in vivo. Per confermare il coinvolgimento del perossido di idrogeno nell’induzione della rigenerazione nervosa, abbiamo effettuato registrazioni elettrofisiologiche ed esperimenti di immunoistochimica, ed entrambi gli approcci sperimentali hanno dimostrato che in la somministrazione di catalasi in vivo ritarda il processo di rigenerazione nervosa in muscoli intossicati. Inoltre, il pre-trattamento con un inibitore della via di ERK - PD98059 – rallenta la il recupero dall’intossicazione con una cinetica molto simile a quella osservata in presenza di catalasi, supportando l’idea che in effetti il perossido di idrogeno promuova la rigenerazione nervosa attraverso l’attivazione della via di ERK nelle CSPs
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Song, Hua. "Investigation of Reaction Networks and Active Sites in Bio-ethanol Steam Reforming over Cobalt based Catalysts." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243999804.
Повний текст джерела
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Reichle, Rainer. "Exotic Species of Hydrogen." [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10236320.
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Braden, Drew J. "Fuel cell grade hydrogen production from the steam reforming of bio-ethanol over co-based catalysts an investigation of reaction networks and active sites /." Connect to this title online, 2005. http://hdl.handle.net/1811/301.
Повний текст джерелаАнотація:
Thesis (Honors)--Ohio State University, 2005.Title from first page of PDF file. Document formattted into pages: contains [55] p.; also includes graphics. Includes bibliographical references. Available online via Ohio State University's Knowledge Bank.