Dissertations / Theses on the topic 'Hydrogène vert'
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Phan, Thanh Son. "Élaboration, caractérisation et mise en œuvre d’un catalyseur dans le reformage du biogaz en vue de la production d’hydrogène vert." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2020. http://www.theses.fr/2020EMAC0007.
Full textBiogas production worldwide is increasing steadily. The combustion to generate heat and electricity, and the biomethane production for injection into the city gas grid are currently the two major industrial applications of biogas. Current research on biogas valorization targets the production of high-value products such as hydrogen for transportation. This is the main objective of the VABHYOGAZ3 project funded by ADEME, which aims at deploying the production of H2 from biogas in the Tarn department, France. Biogas steam reforming, adopted by the industrial partners of the VABHYOGAZ3 project, is a commonly used process in the industry to reform natural gas, but it is a highly energy-consuming process. This PhD thesis aims to develop efficient catalysts for the Dry Reforming of Methane (DRM: conversion of CH4 and CO2 into syngas - mixture of CO and H2) and for the Tri-Reforming of Biogas (Tri-RB: conversion of CH4, CO2, H2O and O2 into syngas). The ultimate goal was to optimize the energy efficiency of the overall process of H2 production through the reforming of biogas, which is essential to make the process economically viable. In fact, DRM and Tri-RB catalysts usually have the problem of catalytic deactivation due to coke deposition and thermal sintering at high temperature (> 700 °C). Obtaining an efficient catalyst under severe conditions of DRM and Tri-RM is crucial for the deployment of these processes at large industrial scale. First, a study on the thermodynamics of the overall processes for H2 production via the reforming of biogas was carried out. Mass and energy balances of these processes were also obtained by ASPEN simulation. Then, various nickel-based catalysts supported on hydroxyapatite (HAP) and on hydroxyapatite substituted with Mg (Mg_HAP) were prepared and characterized. HAP-based supports are considered to be new catalytic materials which have suitable properties for heterogeneous catalysis, in particular for high temperature processes such as DRM and Tri-RM. In this study, HAP supports having the Ca/P molar ratio of 1.55, 1.67 and 1.75, and Mg_HAP (substitution of 2.2, 5.8 and 8.5 % of Ca with Mg) have been synthesized. These supports were doped with 5 wt.% of Ni by incipient wetness impregnation method. These catalysts were evaluated for both DRB and Tri-RB reactions in a fixed bed reactor. A parametric study on the influence of operating conditions including temperature, total pressure, biogas feeding rate, and molar ratio of steam to methane (S/C) and oxygen to methane (O/C), has been performed. The objective was to compare and identify the best catalysts and the best operating conditions. Mass balances have been established experimentally. Catalytic deactivation has been discussed and evidenced. Finally, the stability of the best catalysts was studied for a long reaction time of 150-300 h, and catalyst regeneration was also performed. This work shows that Ni-based catalysts supported on HAP or on Mg_HAP are competitive to the best catalysts identified in the literature. This work also confirms the interest of the use of new HAP-based supports in heterogeneous catalysis and particularly in high temperature processes
Alex, Ansu. "Tidal stream energy integration with green hydrogen production : energy management and system optimisation." Thesis, Normandie, 2022. http://www.theses.fr/2022NORMC216.
Full textThe overarching aim of this thesis is to design, implement and compare different energy management strategies and optimisation approaches for a hybrid system involving floating tidal stream energy integration with green hydrogen production. Towards reaching the objectives, the individual system components are modelled initially. The annual system performance capabilities of the tidal stream energy plant are then obtained using frequently occurring daily profiles at the Fall of Warness berth in the Orkney Islands, Scotland. The transitionary operating modes of two polymer electrolyte membrane electrolyser units, when subjected to the energy from the tidal stream plant are analysed based on a rule-based approach energy management strategy. Later, a preliminary evaluation of the hydrogen production cost is assessed based on different daily hydrogen demand and daily tidal profile conditions. Further, an optimisation approach with the objective to maximise the system operating profit ensuring optimal and sufficient operations of both the electrolyser units under real system constraints, is formulated with priority for tidal energy powered hydrogen production. The optimisation problem is solved using a genetic algorithm based on the mixed integer non-linear problem. A comprehensive cost-benefit analysis based on fixed-variable costs and levelised costs factors is performed to analyse the optimal techno-enviro-economic operation of a hybrid grid connected tidal-wind-hydrogen energy system. The outcomes are compared against the rule-based approach results. The annualised profits in the optimisation approach are estimated to be 41.5% higher compared to the rule-based approach. Further, from an environmental view, the best optimisation results are approximately 47% higher than the rule-based approach results in terms of carbon emission reductions. A dynamic electrolyser capable of working at twice of its nominal power rating for limited duration, resulted particularly advantageous when coupled with tidal energy which is cyclic in nature with predictable periods of high and low power generation. Finally, it was determined that the fixed cost (FC) optimisation approach is relatively simple in terms of cost estimation. On the contrary, while the levelised cost (LC) approach yields slightly better results, it necessitates a greater prior knowledge of system operations to reasonably estimate the cost factors. The proposed method can be used as a generic tool for electrolytic hydrogen production analysis under different contexts, with preferable application in high green energy potential sites with constrained grid facilities
Risal, Laura-Line. "Production d’Hydrogène par Photo-Catalyse de TiO2." Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAE021.
Full textTo circumvent the intermittency of the renewable energies, the use of an energy vector like Hydrogen seems to be an ideal solution. It represents a good way to store energy massively over long periods to be later employed in a wide variety of systems such as mobility, heating or industrial processing, with no impact on the carbon footprint. This source of energy then appears then to be a good alternative to fossil fuels on which we are very dependent. However, 95% of hydrogen is currently produced by the technique of steam reforming of natural gas, which leads to a significant production of carbon dioxide (CO2)! It is therefore necessary to produce it by other techniques and, among the various technologies available, the production by using photocatalysis (a process using only sunlight and water) seems quite appropriate given the possibility of coupling this technique to a renewable energy source such as sunlight. The best-known and most currently used photocatalyst is titanium dioxide (TiO2), but its synthesis requires high temperatures on the scale of several hundreds of degrees. Moreover, its photocatalytic activity is limited and it is generally doped with noble metals in order to increase its photocatalytic power. Given this problem, as part of this doctorate, a new process for TiO2 synthesis under mild conditions at 50°C has been implemented. The materials obtained were then doped with non noble metals such as zinc (Zn), magnesium (Mg), aluminum (Al). Pressure doping tests were also carried out and the hydrogen production results obtained under visible light are very promising
Sood, Sumit. "Multiphysics modelling for online diagnosis and efficiency tracking : application to green H2 production." Thesis, Université de Lille (2018-2021), 2021. https://pepite-depot.univ-lille.fr/LIBRE/EDMADIS/2021/2021LILUB028.pdf.
Full textRenewable Energy Sources (RES) have emerged as a sustainable alternative to carbon-based energy sources as the world is struggling in limiting the greenhouse effect in the coming years. The use of RES, such as solar and wind, alone is non-reliable due to their intermittent nature. The surplus electricity generated during off-peak hours must be stored to tackle the problem of the unavailability of energy. Green Hydrogen (GH$_2$) generation using electrolyser running on RES has seen an increase in recent years for the storage of this surplus energy due to its advantages over conventional methods (such as batteries and ultra-capacitors) for long term storage and transport. Proton Exchange Membrane (PEM) based electrolysers are better suited for the coupling with RES as compared to the alkaline electrolysers due to their faster start-up times and fast dynamic load changing capability. The intermittent nature of RES affects the performance and operation dynamics of the PEM electrolyser and must be analysed and studied in order to make these systems more reliable and safer to use. Mathematical modelling is one of the possible solutions for studying their behavior and developing supervision algorithms.Under the framework of the E2C project of the European Interreg 2-Seas program, a generic dynamic multi-physics model of a PEM electrolyser has been proposed in this work based on Bond Graph (BG) approach. Various components of the PEM electrolyser have been modelled in the form of BG capsules. These capsules can be connected based on the piping and instrumentation diagram of the PEM electrolyser system to have a global model of the system. The developed model is capable of representing different configurations of PEM electrolysers ranging from laboratory scale to industrial scale. The model is also capable of facilitating efficiency tracking in real-time. The developed model in the BG form has been converted into MATLAB® Simulink block diagram from the implementation point of view.The model was then validated using a single cell PEM electrolyser powered by a Hybrid Multi-source Platform (HMP) running on solar and wind energy at the University of Lille. The proposed model was also extended for the modelling and performance study of Anion Exchange Membrane (AEM) electrolysis cell, in collaboration with the University of Exeter of England, which shares a similar configuration and architecture.The developed model for the PEM electrolysis system is also suitable for the development of control, diagnosis, and prognosis algorithms. Therefore, a model-based robust fault diagnosis for PEM water electrolyser has been proposed in this work. The proposed diagnosis algorithms and model have been then utilized for developing the graphical user interface for online supervision
Queyriaux, Nicolas. "Vers la construction d'une photocathode de production d'hydrogène par une approche moléculaire." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV033/document.
Full textThere is an urgent need to provide solutions for the energetic challenge our planet has to face. The production of “environmentally friendly” fuels such as dihydrogen H2 through sunlight-driven water splitting holds great promise. Hydrogen is indeed a carbon-free energy carrier that can be stored and used on request to produce electricity thanks to the mature fuel cell technology. Moreover, water and solar energy form the ideal couple for H2 production because they are both readily available and their use is considered to be safe for the environment. The design and study of molecular photocatalytic systems for H2 evolution from water has therefore been the subject of intensive research interest in the last decade and their implementation into functional dye-sensitized photoelectrocatalytic cells recently appeared in the literature. It is nevertheless necessary to optimize the efficiency of these molecular systems in order to reach the targeted solar-to-hydrogen conversion yield. In that context, this PhD thesis aimed at getting a better understanding of parameters relevant for the optimization of molecular H2-evolving photocathodes: first, different coupling strategies have been studied to covalently assemble a light-harvesting unit with a redox-active moiety; second, a synthetic methodology allowing introduction of robust anchoring groups in the coordination sphere of ruthenium photosensitizers has been widely studied and the first photoelectrodes characterized; finally, a new series of proton reduction catalysts featuring a polypyridinic ligand has been investigated, allowing important kinetic and mechanistic insights to be obtained
Rit, Martin. "Évaluation du potentiel de rénovation énergétique d'un territoire dans le cadre de démarches de massification." Electronic Thesis or Diss., Université Paris sciences et lettres, 2024. http://www.theses.fr/2024UPSLM009.
Full textResearch efforts must focus on resolving energy issues on a global scale, with the aim of reducing energy consumption and greenhouse gas emissions in order to mitigate the impact of climate change. In 2020, the building sector in France was responsible for around 45% of final energy consumption and 19% of greenhouse gas emissions, representing amajor source of savings.This thesis explores the energy renovation of the French residential building stock, focusing on the evaluation of territorial strategies through modelling and optimisation.With this in mind, the work involves (1) characterising and simulating the French building stock using data and an Open Source energy simulation model, (2) calibrating this model on actual electricity and gas consumption for the whole of France, (3) optimising energy renovation trajectories by activating levers at the level of each building in the territory and (4) applying this model to a stock of several tens of thousands of buildings using clustering algorithms. An analysis of the combinatorics of the optimisation problem is carried out, placing the question of the dimensionality of the renovation solutions, the temporal granularity of the optimisation and the number of constraints at the heart of this work.The method developed in this work was applied to discuss the relevance of climate plans defined in various French conurbations for achieving the National Low Carbon Strategy in 2050. The results of this study provided a quantified assessment of the investments required and the public subsidies to be granted in these major cities, as well as a timetable for carrying out the renovation work according to the different types of building. This thesis proposes a decision-making tool that can be used for a large number of buildings (several thousand), regardless of their geographical location in France, and with a replicable and transparent method
Al, Bacha Serge. "Générateur d’Hydrogène « vert » pour mobilité légère ou de courte distance Hydrogen generation via hydrolysis of ball milled WE43 magnesium waste Hydrogen generation from ball milled Mg alloy waste by hydrolysis reaction Effect of ball milling strategy (milling device for scaling-up) on the hydrolysis performance of Mg alloy waste Effect of ball milling in presence of additives (Graphite, AlCl3, MgCl2 and NaCl) on the hydrolysis performances of Mg17Al12 Corrosion of pure and milled Mg17Al12 in “model” seawater solution Mechanism of hydrogen formation during the corrosion of Mg17Al12 Hydrolysis properties, corrosion behavior and microhardness of AZ91 "model" alloys SECM investigation of galvanic coupling between Mg and Mg17Al12 in AZ alloys Valorization of AZ91 by the hydrolysis reaction for hydrogen production (Electrochemical approach) Clean hydrogen production by the hydrolysis of Magnesium-based material: effect of the hydrolysis solution." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0312.
Full textThe hydrolysis of magnesium alloys wastes in seawater (i.e. 3.5 wt.% of NaCl aqueous solution) is a new approach which allows both in-situ hydrogen production and the valorization of a priori non-recyclable wastes. The objective of this research work is to optimize the reactivity of magnesium-based wastes by ball milling with additives. Therefore, we investigated the effects of the main milling parameters (e.g. milling atmosphere, milling rotation speed, order of the addition of additives) on the reactivity of WE43 alloys and Mg – Al alloys wastes. A « scale-up » of the materials treatment process was conducted to explore the possibility of industrializing the process. In addition, we have shown that milling under argon is more advantageous than under hydrogen.Mg – Al alloys (more precisely AZ91) are the most widely used. In these alloys, Al forms with Mg the intermetallic Mg17Al12. To better understand the mechanism of hydrogen production from these binary Mg – Al alloys (Mg + Mg17Al12), evaluating the behavior of each of their constituents and their interactions is essential. In this regard, the chemical (i.e. hydrolysis) and electrochemical (i.e. corrosion) aspects of the reaction of Mg17Al12 with the model seawater solution and the effect of milling in the presence of additives (e.g. graphite, NaCl, MgCl2 and AlCl3) were studied. The evolution of the surface chemistry during polarization tests has proven experimentally (by Raman spectroscopy), for the first time, the formation of reaction intermediate and has allowed us to propose a mechanism of H2 formation.The interaction between Mg and Mg17Al12 was explored by comparing the properties of model materials of « AZ91 » (Mg + Mg17Al12). Using scanning electrochemical microscopy, the effect of galvanic coupling was studied at the interface of the two components of the material. In view of these studies, the contribution of Mg17Al12 in the corrosion of AZ91 alloys was clarified. The intermetallic is corrosion resistant and accelerates the corrosion of Mg due to galvanic coupling. The various milling strategies adopted in this work were compared by applying them to a commercial AZ91 alloy. Mechanical treated materials with graphite and AlCl3 showed the highest hydrolysis performances.Finally, we semi-quantitatively evaluated the purity of H2 (the composition of the gas mixture and its humidity) produced. The impact of few experimental conditions (e.g. composition of the solution, temperature, ratio of the mass of powder to the volume of solution) is reported. Thus, it has been shown that an Mg hydrolysis reactor operating at room temperature with seawater produces « clean » hydrogen in-situ and can be considered as a « green » hydrogen on demand generator
Zhou, Zhou. "Synthèse et études structurales de nouveaux [α/aza]-oligomères et cyclooligomères, vers de nouveaux foldamères." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0300/document.
Full textThis work describes the synthesis and structural analysis of mixed oligomers and their cyclic analogues containing an alternation of α-acid residues and α-azaamino acids moieties. The first chapter deals with the “in solution” synthesis of 1:1-[α/aza]-oligomers and 2:1 [α/aza] oligomers respectively, obtained by oligomerization of the properly deprotected azadipeptide Boc-Ala-azaPhe-OMe azadipeptide and Boc-Phe-Ala-OMe-azaPhe tripeptide. For the first family series with L aminoacids, yields dimerization and trimerization are moderate due to the low nucleophilicity of the amine azadipeptidic partner. Concerning the 2:1-[α/aza]-oligomers of variable sizes, they were isolated with very good yields whatever the nature L and / or D of the α-aminoacid residues of the azatripeptide. This chapter also presents the conformational study of these oligomers by NMR and IR spectroscopy, molecular modeling and in some cases by X-ray diffraction. Analysis of the 1:1 [α/aza] oligomers reveals mainly an self-assembly in solution with alternation of β- and γ-turns stabilized by intramolecular hydrogen bonds. Examination of the 2:1 [α/aza] oligomers in homochiral series (L) evidenced a main conformation with repetitive β turns. Regarding the heterochiral series (DLDL….), it is an alternation of β- and γ-turns which is observed. The second chapter is devoted to the solution synthesis in solution and conformational study of cyclic analogues oligomers presented in the first chapter. 2: 1-[α/aza]-cyclooligomers are mostly discussed because their synthesis by intramolecular peptide coupling is more effective than the 1:1 [α/aza]-cyclooligomers. The formation of nanotubes due to the stacking of the homochiral (L) 2:1-[α/aza]-cyclohexamers has been shown in the solid state and suggested in solution. Furthermore, in heterochiral series, the gelling properties of some organic solvents suggest a self-assembly in solution
Cany, Camille. "Interactions entre énergie nucléaire et énergies renouvelables variables dans la transition énergétique en France : adaptations du parc électrique vers plus de flexibilité." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC015/document.
Full textThe French power system is transitioning towards a more diversified low carbon mix. The power mix is characterised by a high nuclear share which is to remain significant and the target to increase variable renewables (wind and solar) by 2050. When introduced massively, wind and solar trigger new needs for back-up power, both in the short and long term, to answer the flexibility required in order to maintain the reliability target level of the power system. All flexibility options should be complementarily developed, given their characteristics, and nuclear will have a role to play in this context.How could the French power mix be adapted towards more flexibility while maintaining a low-carbon level and mastering associated costs? The purpose of this PhD thesis is to shed light on this issue thanks to a techno-economic analysisAt first, interactions between nuclear and variable renewables are analysed thanks to two complementary approaches. On the one hand, a technical perspective is adopted by confronting prospective nuclear load-following requirements to the fleet theoretical capabilities. On the other hand, thanks to a techno-economic approach, we evaluate the additional cost of ensuring part of the flexibility requirements with the nuclear fleet and examine options to reduce this cost to make nuclear back-up competitive. These two approaches are based on the construction of realistic scenarios by 2030 and 2050.The French nuclear fleet will be asked for a strong increase of the load following operations with growing wind and solar shares. Even if the nuclear fleet can enable higher power ramps and amplitude variations, when wind and solar account for more than 30% in the total demand, compensating for the power variations induced would require complementary means. From a fleet management perspective, it would be beneficial to favour wind compared to solar in the power mix. The latter induces extreme power ramps and amplitudes for the nuclear fleet.The nuclear production cost could be significantly increased with the decrease of the nuclear utilisation rate. In the transition phase, it would be of great importance to promote a progressive replacement of the nuclear fleet to compensate for the production cost increase. In the case of new nuclear investments, a carbon price increase could make nuclear back-up able to compete with combined-cycle gas turbine plants as the alternative back-up option. Anticipating the development of new outlets becomes crucial to guide future investments in low-carbon power plants.To bypass the issue of the nuclear utilisation rate reduction, it would be worth considering taking advantage of the available excess energy to produce valuable products while providing flexibility services to the grid. Hydrogen production, as a flexible power demand, could enhance synergies between nuclear and variable renewables through new markets to valorise the excess nuclear energy. When wind and solar shares increase, along with the hydrogen market expected growth driven by mobility uses, opportunities are created for the nuclear operator. If the French nuclear capacities are maintained and if an adapted business model is developed, nuclear-hydrogen coproduction could answer the hydrogen demand by 2030. Other options could be considered to find outlets to the excess power such as the development of power exportations or the coproduction of heat and electricity.Overall, in order to foster synergies between low-carbon power plants, the change of the nuclear share in the French power mix should be apprehended through dynamics adapted to the penetration of renewables as well as to the deployment of hydrogen markets, and new markets in general
Tournadre, Léa. "Vers une meilleure compréhension des mécanismes de déformation par croissance libre sous irradiation des alliages de zirconium." Thesis, La Rochelle, 2012. http://www.theses.fr/2012LAROS390.
Full textThe aim of this PhD work is to have a better understanding of axial elongation of the PWR fuel assemblies manufactured in zirconium alloys (Zy-4 or M5). More specifically, we focused on the growth acceleration of these assemblies, clearly correlated to the nucleation of specific irradiation defects: the c-loops. Irradiations by charged particles were performed in order to reproduce the microstructure evolution and to study its representativeness. Thus, primary damage morphology has no impact on the c-loop microstructures where as the damage creation rate (like the temperature) seems to play a major role. Moreover, the nucleation dose for c-loops appears clearly correlated to the nuclei and vacancy clusters growth kinetics. This kinetics could be influenced by the damage creation rate, the alloying elements, but also by an applied stress or the hydrogen content (which can be introduced during oxidation in reactor). Thus, this work has explored the effect of an applied stress (in the elasticity or plasticity domain) and the impact of the hydrogen pick-up on the nucleation and growth of c-loops. In accordance with the SIPA mechanism described in the literature, we observed an effect of the applied stress on the c-loop microstructures. Moreover, this study clearly shows an impact of hydrogen in solid solution and as precipitated hydrides on the nucleation and growth of c-loops
Ngo, Biboum Bimbong Rosa. "Polyoxométallates et chimie verte : molécules et matériaux nanostructurés pour la conversion de l’énergie et l’environnement." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112095/document.
Full textThis thesis focuses on the synthesis of nanostructured composite materials based on polyoxometalates for energy conversion and applications to environmental problems. To achieve these goals, many new compounds of this family of molecular oxides were synthesized and were associated with different nature friendly matrices, in agreement with the main criteria of Green Chemistry. In the field of energy, the new catalysts have proved very effective in important but difficult to achieve reactions, such as producing hydrogen, oxygen reduction or water oxidation. Similarly, among applications to pollution problems, these nanomaterials have shown a strong electrocatalytic and photocatalytic activity for the reduction of nitrogen oxides, bromate and for the photodegradation of a toxic textile dye, Acid Orange 7. The performances of these new catalysts are comparable to those of the best known systems
Saad, Ali. "Vers des conducteurs organiques chiraux : synthèses et propriétés de tétrathiafulvalènes dérivés du binapthol." Rennes 1, 2010. http://www.theses.fr/2010REN1S130.
Full textThe introduction of chirality in organic conductors is the subject of recent efforts aimed at the observation of anisotropic magneto-chiral effects on the conductivity, as recently discovered in carbon nanotubes. As precursors of such chiral conductors, two original series of tetrathiafulvalene molecules functionalized with one or two binaphtol moieties with axial chirality were prepared and investigated. The first series, with a methylene spacer between the TTF and the binaphtol moieties, gave rigid molecules. Electrochemical studies of the enantiopure symmetrical (RR) and (SS) molecules show an unexpected but selective formation of stable mixed valence dimers. The introduction of hydrogen bonds via amide functions contribute to the formation of helical structures. Enantiopure charge transfer salts were obtained with the unsymmetrical binaphtolmethylene-EDT-TTF. The second series with an ethylenethio spacer between the TTF and the binaphtol moieties, exhibits an increased flexibility but decreased donor ability. Salts of the unsymmetrical binaphtolethylenethio-EDT-TTF were isolated from its oxidation with TCNQ and TCNQF₄. Finally, the very first nickel dithiolene complexes incorporating a chiral binaphtol moiety are described
Chochois, Vincent. "Implication des réserves carbonées dans le photoproduction d'hydrogène chez l'algue verte Chlamydomonas reinhardtii." Aix-Marseille 2, 2009. http://theses.univ-amu.fr.lama.univ-amu.fr/2009AIX22074.pdf.
Full textThe unicellular green alga Chlamydomonas reinhardtii is able to produce hydrogen, using water as an electron donor, and sunlight as an energy source. Although this property offers interesting biotechnological perspectives, a major limitation is related to the sensitivity of hydrogenase to oxygen which is produced by photosynthesis. It had been previously shown that in conditions of sulfur deprivation, C. Reinhardtii is able to produce hydrogen during several days (Melis et an. 2000). During this process, two pathways, one direct depending on photosystem II (PSII) activity and the other involving only the PSI, are involved, starch reserves being supposed to play a role in both of these pathways. The purpose of this phD thesis was to elucidate the mechanisms linking starch catabolism to the hydrogen photoproduction process. Firstly, the analysis of mutants affected in starch biosynthesis (sta6 and sta7) showed that if starch reserves are essential to the functioning of the indirect pathway, they are not involved in the direct one. Secondly, in order to identify metabolic steps and regulatory processes involved in starch breakdown, we developed a genetic approach based on the search of mutants affected in starch reserves mobilization. Eight mutant (std1 to std8) diversely affected in their ability to degrade starch after an accumulation phase have been isolated from an insertional mutant library of 15,000 clones. One of these mutants, std1, is affected in a kinase related to the DYRK family (dual‐specificity tyrosine regulated serine threonine kinase). Although the targets of this putative kinase remain to be identified, the analysis of the granulebound proteome displayed profound alterations in the expression profile of starch phosphorylases, potentially involved in starch breakdown. STD1 represents the first starch catabolism regulator identified to date in plants
Metayé, Romain. "Vers une photoproduction de l'hydrogène par des catalyseurs immobilisés bio-inspirés." Palaiseau, Ecole polytechnique, 2010. http://www.theses.fr/2010EPXX0074.
Full textLecomte, Frédéric. "Structures d'agrégats moléculaires : vers la spectroscopie infrarouge couplée à la formation d'anions dipolaires." Paris 13, 2002. http://www.theses.fr/2002PA132026.
Full textMerkas, Sonja. "Oligonucléotides à Porphyrines Pendantes : vers des Nano-Matériaux Multi-Porphyriniques Auto-Assemblés." Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00259102.
Full textDans le but d'organiser des porphyrines dans l'espace de façon similaire au système naturel, un squelette oligonucléotidique a été choisi pour l'élaboration de nanosystèmes multi-porphyriniques. C'est dans cette optique que nous avons réalisé la synthèse d'oligodeoxynucléotides fonctionnalisés par des porphyrines. La préparation de ces systèmes est fondée sur l'oligomérisation en O-3'et O-5' d'un dérivé de la 2'-deoxyuridine fonctionnalisé par une porphyrine. L'architecture de ces systèmes a été dessinée sur la base de liaisons rigides et souples. Dans le but d'imposer par la conformation de la chaîne oligonucléotidique une organisation parallèle aux porphyrines, ces dernières sont greffées en C-5 de l'uracile par un espaceur rigide et les uridines reliées entre elles par une liaison souple. Un mono-, un di-, un tetra- et un octa-deoxynucléotides à porphyrines pendantes ont notamment été synthétisés.
Un agencement approprié des porphyrines base-libre et métallées au Zn(II) au sein du fil moléculaire oligonucléotidique a permis de mettre en évidence un transfert d'énergie de l'état excité de la porphyrine de Zn(II) vers les porphyrines base-libre. On observe une nette contribution de la porphyrine de Zn(II) à l'émission des porphyrines base-libre.
La série des oligonucléotides a été métallée au Zn(II) dans le but d'examiner l'effet du degré d'oligomérisation de ces architectures moléculaires sur leur capacité de complexation de bases bidendates telle que le DABCO. Nous avons pu montrer que la coordination de DABCO est favorisée au fur et à mesure de l'élévation du degré d'oligomérisation grâce à la pré-organisation conformationnelle qui s'instaure au sein du squelette oligonucléotidique.
Enfin, nous nous sommes intéressés à l'auto-assemblage par liaisons hydrogène que peut établir la base nucléique uracile avec un synton complémentaire telle que la triazine fonctionnalisée par des porphyrines. Des études quantitatives de stabilisation des architectures supramoléculaires ont mis en évidence des interactions intermoléculaires secondaires de type p-p entre les porphyrines au sein du complexe supramoléculaire formé.
Mus, Florence. "Activité NAD(P)H plastoquinone oxydoréductase et photo-production d'hydrogène au sein des thylacoïdes de l'algue verte Chlamydomonas reinhardtii." Aix-Marseille 2, 2005. http://www.theses.fr/2005AIX22094.
Full textMcLaughlin, Elizabeth A. "Microbial hydrogen oxidation associated with deep-sea hydrothermal vent environments /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/10967.
Full textVentura, Aude. "Polymères sous rayonnements ionisants : étude des transferts d’énergie vers les défauts d’irradiation." Caen, 2013. http://www.theses.fr/2013CAEN2048.
Full textRadiation-induced defects created in polymers submitted to ionizing radiations, under inert atmosphere, present the same trend as a function of the dose. When the absorbed dose increases, their concentration increase then level off. This behavior can be assigned to energy transfers from the polymer to the previously created macromolecular defects; the latter acting as energy sinks. During this thesis, we aimed to specify the influence of a given defect, namely the trans-vinylene, in the behavior of polyethylene under ionizing radiations. For this purpose, we proposed a new methodology based on the specific insertion, at various concentrations, of trans-vinylene groups in the polyethylene backbone through chemical synthesis. This enables to get rid of the variety of created defects on one hand and on the simultaneity of their creation on the other hand. Modified polyethylenes, containing solely trans-vinylene as odd groups, were irradiated under inert atmosphere, using either low LET beams () or high LET beams (swift heavy ions). During irradiations, both macromolecular defects and H2 emission were quantified. According to experimental results, among all defects, the influence of the trans-vinylene on the behavior of polyethylene is predominant
Elayoubi, Mustapha. "Transfert d'atomes d'hydrogène vers la cathode d'un arc réducteur de composition argon-hydrogène /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1989. http://theses.uqac.ca.
Full textBento, Nuno. "La transition vers une économie de l'hydrogène : infrastructures et changement technique." Phd thesis, Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00463857.
Full textBento, Nuno. "La transition vers une économie de l'hydrogène : infrastructures et changement technique." Phd thesis, Grenoble, 2010. http://www.theses.fr/2010GRENE005.
Full textThe double constraint of climate change and increasing scarcity of oil requires that we consider alternative energies for the medium term. This thesis focuses on the development of a hydrogen economy, which is conditional on the existence of an infrastructure for the distribution of the new fuel and the readiness of fuel cells. The main idea is that the state can play a central role in both infrastructure implementation and preparation of fuel cells technology. The thesis begins with a techno-economic analysis of the hydrogen-energy chain, which highlights the difficulty of setting up the infrastructure. The study of the development of electricity and gas networks in the past provides the empirical basis supporting the hypothesis that government can play an important role to consolidate the diffusion of socio-technical networks. In addition, private projects of stations may be justified by early-move benefits, although their financial viability depends on the demand for hydrogen which is in turn dependent on the performance of the fuel cell vehicle. The introduction of radical innovations, such as fuel cell, has been made more difficult by the domination of conventional technologies. This assertion is particularly true in the transport sector which was progressively locked into fossil fuels by a process of technological and institutional co-evolution driven by increasing returns of scale. Hence, fuel cells may primarily diffuse through the accumulation of niches where the innovation is closer to commercialization. These niches may be located in portable applications segment. Investments in research and demonstration are still necessary in order to reduce costs and increase performances of fuel cells. Using a simple model of multitechnological diffusion, we analyze the competition between the hydrogen fuel cell vehicle and the plug-in hybrid car for the automotive market. We show that an early entry of the latter may block the arrival of hydrogen in the market. Other than fuel cell preparedness, a mass diffusion of hydrogen requires a sufficient coverage of the supportive infrastructure. The continuation of public support for R & D, a carbon tax (tax or permits) and demand stimulation are measures capable of accelerating the entry of hydrogen in the market
Ngo, Biboum Bimbong Rosa. "Polyoxométallates et chimie verte : molécules et matériaux nanostructurés pour la conversion de l'énergie et l'environnement." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00612028.
Full textBlanchard, Philippe. "Hydroxymethyl-tetrathiafulvalenes : vers un nouveau controle de l'organisation structurale des metaux organiques correspondants par liaison hydrogene." Nantes, 1994. http://www.theses.fr/1994NANT2062.
Full textChateau-Cornu, Jean-Philippe. "Vers une quantification des mécanismes de corrosion sous contrainte : simulations numériques des interactions hydrogène-dislocations en pointe de fissure." Grenoble INPG, 1999. http://www.theses.fr/1999INPG4201.
Full textPerez, Florian. "Production d'hydrogène par la serpentinisation des roches mantelliques : apport de la modélisation à la compréhension des processus physiques et géochimiques." Phd thesis, Université de Bretagne occidentale - Brest, 2012. http://tel.archives-ouvertes.fr/tel-00846873.
Full textPouyet, Frédéric. "Nouvelles conditions d'utilisation de l'ozone dans le blanchiment des pâtes cellulosiques. Application à la mise au point d'un procédé de blanchiment "vert"." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI032.
Full textThe lack of understanding regarding the reactions of ozone with pulp components is one of the reasons why chlorine-free bleaching never really developed. Ozone is actually believed to lead to an extensive degradation of cellulose, contrary to the agent it could replace: chlorine dioxide. However, as the use of chlorinated compounds has many drawbacks, including the generation of toxic compounds, non-degrading chlorine-free bleaching sequences have to be designed. To do so, a better understanding of reactions involving ozone and hydrogen peroxide has to be gained. The first part of this very work consisted of a literature review. In the second part, some of the main hypotheses extracted from the literature were compared with other elements and first results, to show they inevitably led to contradictions and that new theories were needed. The third part was dedicated to ozone. The order of its reactions with pulp components was first of all checked. The properties of pulps of various compositions were then measured through ozonations. This study led to a new hypothesis, which was validated thanks to ESR spectroscopy. The reaction of ozone with some non-aromatic unsaturated compounds seems to give radical species. Those radical species would be in turn responsible for the depolymerization of cellulose, and the formation of carbonyl groups on cellulose as well. The fourth part dealt with the impact of alkaline treatment on cellulose after ozonations. Observations about carbonyl content and degree of polymerization suggest a new mechanism related to carbonyl and nucleophilic agents, explaining a main part of the depolymerization undergone by the cellulose. The last chapter of this work summarizes the trials regarding the optimisation of a chlorine-free bleaching sequence. It proves that high-quality pulps can be obtained by chlorine-free processes
Ventura, Aude. "Polymères sous rayonnements ionisants : étude des transferts d'énergie vers les défauts d'irradiation." Phd thesis, Université de Caen, 2013. http://tel.archives-ouvertes.fr/tel-00950232.
Full textMomjian, Emmanuel. "Sensitive very long baseline interferometry studies of interacting/merging galaxies." Lexington, Ky. : [University of Kentucky Libraries], 2003. http://lib.uky.edu/ETD/ukyphys2003d00108/EMthesis.pdf.
Full textTitle from document title page (viewed onJune 1, 2004). Document formatted into pages; contains ix, 106 leaves : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 99-104).
Mégret, Claire. "Détermination par des calculs DFT de la relation entre énergies de liaison H-C et M-C : Vers une évaluation du contrôle thermodynamique de la sélectivité d'activation C-H." Montpellier 2, 2004. http://www.theses.fr/2004MON20061.
Full textAhlman, Robert. "ASSESSMENT OF GOVERNING HEAT AND MASS TRANSFER COEFFICIENTS FOR CRYOGENIC NO-VENT TOP-OFF MODELING." Cleveland State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=csu1625819994533715.
Full textPoggi, Philippe. "INTEGRATION DES SYSTEMES ENERGETIQUES A SOURCES RENOUVELABLES DANS LES RESEAUX ELECTRIQUES INSULAIRES." Habilitation à diriger des recherches, Université Pascal Paoli, 2007. http://tel.archives-ouvertes.fr/tel-00604868.
Full textPefoute, Takom Eric William. "Vers une meilleure compréhension du stockage de l'Hydrogène dans les clathrate hydrates : analyse de leur dynamique par simulation de dynamique moléculaire et par diffusion quasi élastique de neurtrons." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14049/document.
Full textThe expected disappearance of fossil fuels in the near future is one of the major challenges of this century which we need to face up and it is necessary to anticipate it. For that, it will be convenient that we have begun the primary energy transfer used today to renewable energy. The sector of transport is one of the most concerned by these renewable energies. An application in this sector would require numerous research works and it is in this context that the hydrogen storage inside the clathrate hydrates has been undertaken during my PhD. This work aimed at investigating the host-guest interactions (dynamics) of clathrate hydrates and ranged from the synthesis of clathrate hydrates to the insertion of hydrogen within them. This study has been done both from experimental and theoretical point of view. Molecular Dynamics (MD) simulations were used to guide the interpretation of incoherent Quasi-Elastic Neutron Scattering (QENS) experiments. At first, we developed a methodology combining MD and QENS to investigate the dynamics of bromomethane clathrate hydrate, a prototypical system. Having validated the multi-technique approach, the methodology has been applied to investigate clathrate hydrates involved in the hydrogen storage problematic. In this issue, the tetrahydrofuran (THF) clathrate hydrate, used as host sub-structure for storing hydrogen, has been studied. An original experimental set-up has been developed for the preparation of a binary H2-THF clathrate hydrate. The analysis of QENS experiments performed on this binary clathrate hydrate revealed the existence of localized translational motion of hydrogen molecules within the clathrate cages
Al-Shameri, Ammar [Verfasser], Lars [Akademischer Betreuer] Lauterbach, Peter [Gutachter] Neubauer, Lars [Gutachter] Lauterbach, Bettina [Gutachter] Nestl, and Vera [Gutachter] Meyer. "Powering biocatalytical reactions with hydrogen / Ammar Al-Shameri ; Gutachter: Peter Neubauer, Lars Lauterbach, Bettina Nestl, Vera Meyer ; Betreuer: Lars Lauterbach." Berlin : Technische Universität Berlin, 2020. http://d-nb.info/1220356026/34.
Full textLomax, Franklin D. "Investigation of steam reformation of natural gas for the very small scale production of hydrogen fuel for light duty vehicles in appliance-type refueling systems." Master's thesis, This resource online, 1997. http://scholar.lib.vt.edu/theses/available/etd-09052009-040323/.
Full textForot, Clément. "Application de la perméation d’hydrogène vers la prédiction des risques de fissuration interne des aciers." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10348.
Full textThe work of this thesis applies to flexible pipelines, which are used as risers or flowlines in offshore production. More specifically, it is dedicated to study the risks of hydrogen embrittlement of carbon steel wires used as armors if flexible pipes. The study is focused on low H2S containing medium inducing slow hydrogen entry in steels, thus, potentially long incubation times before embrittlement becomes effective. The first goal of this work is to study the entry, diffusion and trapping of hydrogen into different grades of carbon steel in low H2S concentration environment. The permeation technique will be used, as well as immersion tests of variable duration with characterization of the crack process. Analysis of permeation transients gives information on hydrogen diffusion and hydrogen trapping into steels in function of experimental conditions (pH, PH2S). Immersion tests will be performed complementary to permeation tests in various conditions of pH and PH2S. We verify the cracking evolution with environmental conditions. We also quantify the lattice hydrogen, the reversibly and irreversibly trapped hydrogen absorbed by the materials. Then, using both diffusion properties from permeation tests and cracking data from immersion experiments, we set up a predictive approach to link the risks of H2S cracking for each steel grade in function of the severity of the environment. Applying this method should also allow to establish faster and more reliable comparisons of the hydrogen induced cracking resistance of different steel grades. It should be used as complimentary tool for qualification purposes
Rahantaniaina, Marie Sylviane. "Vers une meilleure compréhension des systèmes antioxydants chez la plante face aux contraintes environnementales : approches expérimentales et modélisation mécaniste." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS246/document.
Full textThe most important metabolic pathways in the control of oxidative stress remain to be elucidated in plants. Those linked to glutathione play an important role. However, the reactions responsible for its oxidation have not been clearly identified. Here, analysis based on available biochemical, transcriptomic and genetic data emphasized likely important questions to be elucidated for a full understanding of how stress-related redox regulation might impinge on phytohormone-related signaling pathways. Using a reverse genetics approach and the photorespiratory conditional cat2 mutant, we studied the response and functional importance of three potential routes for glutathione oxidation pathways mediated by glutathione S-transferases, glutaredoxin dependent peroxiredoxins, and dehydroascorbate reductases (DHAR) in Arabidopsis during oxidative stress. Hence, interplay between different DHARs appears to be necessary to couple ascorbate and glutathione pools and to allow glutathione-related signaling during enhanced H2O2 metabolism. In addition to experimental work, modelling is another way to investigate H2O2 production and its metabolism related to catalase activity and ascorbate glutathione pathway. This approach led to major conclusions, that catalase and ascorbate peroxidase can share the load in H2O2 processing even in optimal growth conditions. Furthermore, simulations propose that NADPH availability may determine glutathione oxidation through its influence on monodehydroascorbate reduction. Taken together, experimental results and our kinetic model strengthen that the sensitivity of glutathione status to oxidative stress acts as a suitable sensor of increased H2O2
Rahantaniaina, Marie Sylviane. "Vers une meilleure compréhension des systèmes antioxydants chez la plante face aux contraintes environnementales : approches expérimentales et modélisation mécaniste." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS246.
Full textThe most important metabolic pathways in the control of oxidative stress remain to be elucidated in plants. Those linked to glutathione play an important role. However, the reactions responsible for its oxidation have not been clearly identified. Here, analysis based on available biochemical, transcriptomic and genetic data emphasized likely important questions to be elucidated for a full understanding of how stress-related redox regulation might impinge on phytohormone-related signaling pathways. Using a reverse genetics approach and the photorespiratory conditional cat2 mutant, we studied the response and functional importance of three potential routes for glutathione oxidation pathways mediated by glutathione S-transferases, glutaredoxin dependent peroxiredoxins, and dehydroascorbate reductases (DHAR) in Arabidopsis during oxidative stress. Hence, interplay between different DHARs appears to be necessary to couple ascorbate and glutathione pools and to allow glutathione-related signaling during enhanced H2O2 metabolism. In addition to experimental work, modelling is another way to investigate H2O2 production and its metabolism related to catalase activity and ascorbate glutathione pathway. This approach led to major conclusions, that catalase and ascorbate peroxidase can share the load in H2O2 processing even in optimal growth conditions. Furthermore, simulations propose that NADPH availability may determine glutathione oxidation through its influence on monodehydroascorbate reduction. Taken together, experimental results and our kinetic model strengthen that the sensitivity of glutathione status to oxidative stress acts as a suitable sensor of increased H2O2
Hortala, Laurent. "Synthèse et étude de récepteurs d'amines primaires à structures pyridine et quinoléine oxazolines. Application à l'accélération d'une réaction d'aminolyse d'esters vers de nouveaux transporteurs d'aminoacides." Rouen, 2001. http://www.theses.fr/2001ROUES002.
Full textImpéror-Clerc, Marianne. "Étude de transition de phase vers les phases cubiques des systèmes eau/surfactant." Paris 11, 1992. https://tel.archives-ouvertes.fr/tel-01989797.
Full textLy, Céline. "Caractérisation d'aciers à très haute limite d'élasticité vis-à-vis de la fragilisation par l’hydrogène." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2009. http://www.theses.fr/2009ECAP0004/document.
Full textThe distinctive feature of Very High Strength Steels (VHSS) is to present a good combination of ductility and high strength. This makes them particularly interesting for the automotive industry because of the increasing demand for the reduction of car weight and the improvement of passengers security. However, it is known that increasing mechanical characteristics enhances susceptibility to hydrogen embrittlement. The aim of this doctoral thesis work is to study the susceptibility to hydrogen embrittlement of four very high strength steels : a DP (Dual Phase), a TRIP (Transformation Induced Plasticity), a CP (Complex Phase) and BAS, a Cr-V enriched high strength steel. Low alloyed steel with lower mechanical properties, HE (high Elasticity) has been used as a reference. Hydrogen transport characteristics in these steels were investigated thanks to electrochemical permeation tests including charging in acid solution, possibly with the addition of a hydrogenation promoter (arsenic). As already observed on other steels, the absence of stationary entry conditions is to be underlined due to its necessity for the evaluation of diffusion characteristics. Diffusivity at room temperature has appeared to be very high in each of the five steels and a correlation between hydrogen diffusion coefficient and microstructure has been drawn : the finer and the more complex it is, the lower is the apparent diffusion coefficient. Moreover, sub-surface concentrations calculated on the permeation transient in the presence of arsenic have revealed relatively high values for the three steels with the higher mechanical properties (TRIP 800, CP 800 and BAS 100). These values comply with the diffusible hydrogen content measured by thermal desorption technique just after permeation. Otherwise, residual hydrogen dosage tests by thermal desorption under vacuum, have indicated that deep trapping is very low for these steels, even after charging under polarisation and in the presence of arsenic. These results can be explained by fine and homogeneous microstructures that are very well developed with few lattice defects. Ordinary tensile tests have shown the necessity of extreme charging conditions (in the presence of a promoter) for VHS steel embrittlement. With an exception in the case of extreme spontaneaous damages created by HIC (blistering, cracking), embrittlement is imputable to diffusible and weakly trapped hydrogen because deeply trapped hydrogen content is very low. In industrial conditions, during acid pickling while in the presence of inhibitors, permeation, dosage and tensile tests results suggest the absence of embrittlement for the steels. Tested inhibitors seem to act as a physical barrier, by adsorption on the bare steel surface, and limit that way hydrogen absorption and corrosion
Ozgul, Ercin. "Geochemical assessment of gaseous hydrocarbons mixing of bacterial and thermogenic methane in the deep subsurface petroleum system, Gulf of Mexico continental slope /." Texas A&M University, 2002. http://hdl.handle.net/1969/223.
Full textMendes, Marinho Stéphanie. "Combustible solaire : caractérisation du mécanisme de transfert de charge dans des molécules photocatalytiques, vers la production de l'énergie par photosynthèse artificielle." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS299/document.
Full textDeveloppment of environment-friendly sources of energy is one of the stakes major for our societies. To hope for the sustainability of Humans on Earth, it is essential to change our consumer habits on energetics by breaking our dependance on fossil fuels, which use leads to ecological desasters and which stocks are running out. The key of this important challenge is the growth of renewable energy sources, and this is called energy transition. The ideal energy would not produce any polluting waste, would be efficient and widely available. Solar energy is an excellent candidate because it is by far the most abundant and promising source of clean energy. Thus, important efforts are made to developp the solar technologies, including artificial photosynthesis.Artificial photosynthesis was created a century ago and is the focus of many interests and researchs. This technology aims at mimicking the natural photosynthesis realized by plants ; and that in order to store the energy coming from the Sun irriadiation in compounds that can be used at demand. Artificial photosynthesis consists in the elaboration of synthetic systems able under light impulsion to realize the water splitting/decomposition reactions in a catalytique way, generating hydrogène or CO2 reduction products, which are called solar fuels thanks to their high energetic potentials. Indeed, photosynthesis begins with the photo-catalysis of water oxidation, which extirpates the electrons and protons of water molecules. And it is these electrons and protons which will be used to produce the solar fuels.Recently, a real commitment to understand deaply the mechanisms that take place during these catalysed reactions seems to appear. These transformations involve multiple photo-induced electron transfers and it returns their study relatively complicated. Thanks to technological breakthroughs, we studied in a thorough way several photocatalytic systems to draw knowledges ; allowing the rationalisation of the design and then the efficiency improvement of future developped systems. These technical advances were possible thanks to interdisciplinary collaborations between chemists and physicists and led to the developpment of a set-up of « double-pump » transient absorption, that enables to characterize the transient species formed and to track down the pathways during two successive photoinduced electron transfers.In the second part of this work, new catalysts were developped for the photocatalysis of water oxidation reaction. The big majority of the studies led so far on this subject concerned molecular systems, but the lack of robustness and reusability of homogeneous catalysts pushed the research towards materials area. Since about forty years, heterogeneous systems were developped for photocatalysis of several reactions. We explored two types of materials, nanoparticules as catalyst in photocatalytic systems ; and polymers that are able on their own to realize all the functions required for the photocatalysis of a reaction such as water oxidation under visible light irradiation.Thus, during this PhD we tried by two approaches to increase the knowledges and the development of artificial photosynthesis. A solution that is still under-developped to fix the energetic issue our society is facing to, is the use of solar fuels ; and it’s imperative for the research to move forward and that energy transition prevails more effectively and widely
Santini, Guillaume. "Vers la prédiction de la structure tridimensionnelle des épingles à cheveux d' ADN et d' ARN comportant un appariement dans la boucle à partir de la théorie de l'élasticité et de la mécanique moléculaire." Paris 6, 2005. http://www.theses.fr/2005PA066355.
Full textSlim, Aref. "Procédé de dépôt et transition vers un plasma poudreux en plasma microonde multipolaire excité à la résonance cyclotronique électronique répartie de méthane." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1338/.
Full textThis work deals deposition of thin films in a multipolar microwave plasma excited at distributed electron cyclotron resonance. We focused on the deposition of homogeneous films based on hydrogenated amorphous carbon or heterogeneous structure based on carbon nanoparticles formed in the plasma volume and embedded in the matrix under growth. The aim of this PhD work is to highlight the influence of different process parameters such as substrate temperature, microwave power and gas residence time on plasma-surface interactions mechanisms as well as the transition to a dusty plasma. Indeed, the transient regime linked to the first growth steps (3D growth, hydrogenation) is followed by a permanent regime controlled by the competition between the hydrocarbon species deposition and the surface erosion from hydrogen formed in the discharge. This erosion forms volatiles species that can take place in the plasma deposition process and, depending on their density and structure (for example C2H2), lead to the transition toward a dusty plasma. In contrast with walls temperature (from -25 to 150°C) and the microwave power (in the range 100-800W) that do not lead a sufficient density of volatiles species, the residence time lead to the formation of a dusty plasma: this transition is obtained when increasing the hydrogen interaction probability with the reactor walls. This study is based on electrical and optical diagnoses of the discharge (Langmuir probe, infra-red and ellipsometric spectroscopies) and on ex-situ analyses of deposited thin films (microscopies, spectroscopies, etc. . . )
Wang, Yun. "Catalyseurs d'oxydation en conditions de chimie verte : métaux non toxiques, eau oxygénée, transformation de la biomasse, recyclage par greffage." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30241.
Full textIn order to develop a chemistry more respectful of the environment, access to sustainable processes is mandatory. More specifically, in the field of oxidation chemistry, use of toxic oxidants has to be banished, use of solvents limited and reusable catalysts developed. In this context, two types of greener approaches have been explored. The first approach concerns removal or replacement of acetic acid, an additive - in association with H2O2, favoring exclusive formation of epoxides with Mn and Fe metal complexes as catalysts. For this objective, two strategies have been explored. The first one consists in introducing fluoroalcohol functions in the second coordination sphere of metal complexes with pyridinophane-based ligand to easily activate H2O2. Those complexes did not enhance the catalytic activity for cyclooctene oxidation reactions in comparison to analogous Mn(II) and Fe(III) complexes with unmodified ligands. However, Ni(II) and Co(II) metal complexes with unmodified ligands display interesting catalytic activity for H2 photoproduction. The second strategy aimed to replace acetic acid. Using silica beads functionalized with COOH pendant arms (SiO2@COOH) as additive and H2O2 as oxidant, catalytic epoxidation reactions catalyzed by Mn(II) and Fe(III) metal complexes with BPMEN ligand displayed significant selectivity towards epoxide. The second approach concerns organic-solvent free (ep)oxidation processes with catalysts based on polyoxometalates (POMs). Catalysts SiO2@PMo and SiO2@PW, respectively obtained by ionic grafting of H3PMo12O40 or H3PW12O40 on silica beads functionalized with NH2 pending functions (SiO2@NH2), have been fully characterized. With low catalyst loading, both catalysts displayed efficient oxidation activity and better selectivity than the free POMs. Moreover, recovered beads gave similar conversion and selectivity after two recycling processes
Lopes, Oliveira Luiz Fernando. "Un modèle physique multiéchelle pour l’analyse de l’électrolyse de l’eau dans des électrolyseurs à membrane échangeuse de protons (PEMWE) : des données ab-initio vers les observables macroscopiques." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10008.
Full textHydrogen energy refers to the possibility of using H2 to transport and produce energy. There are different methods to fabricate H2, among them, water electrolysis. Regarding the existing devices used for the production of hydrogen from water electrolysis, the so-called polymer electrolyte membrane water electrolyzers (PEMWE) have gained attention in the last years. The main objective of this thesis is to provide a multiscale model for the analysis of PEMWE operation. To achieve such goal, we use different theoretical and numerical techniques, due to the several scales that should be treated. This thesis has two main axes. The first one consists of the development of a multiscale transient model describing the operation of a PEMWE single cell. This model includes a detailed description of the elementary electrode kinetics, a description of the behavior of the nanoscale catalyst-electrolyte interface, and a microstructural description of the transport of chemical species and charges at the microscale along the whole membrane electrodes assembly (MEA). We present an impact study of different catalyst materials on the performance of the PEMWE and a sensitivity study to the operation conditions, both evaluated from numerical simulations and with results discussed in comparison with available experimental data. The second axis is devoted to the consideration of the reaction kinetics phenomena at the atomistic scale in more details. For this, we have performed density functional theory (DFT) calculations to provide a detailed description of the adsorption of water on IrO2 and RuO2, two of the most used catalyst materials in PEMWE
Chauvin, Julie. "Etude des mécanismes anti-cancéreux induits par milieux activés par jet de plasma froid : vers une nouvelle approche thérapeutique." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30263/document.
Full textCancer therapies based on physical principles (radiofrequency, ultrasound, laser, electroporation...) have considerably increased in the last decade. Their objectives are to directly destroy cancer cells, to favor the targeted entry of therapeutic molecules or to stimulate the patient's immune system in order to eliminate the tumor. Cold plasma still arouses interest in the field of oncology through its ability to generate reactive oxygen species (ROS) and nitrogen species (RNS) which can be genotoxic and cytotoxic for cancer cells. Two approaches to the use of plasma are studied: either direct exposure of cells to the plasma jet, or indirect exposure via the use of a Plasma Activated Medium (PAM). The PAM being easier to deliver by injection into the tumor, this approach was chosen in this work. The work presented consists in studying the genotoxic and cytotoxic effects of PAM resulting from exposure of the medium to the helium plasma jet on in vitro and in vivo tumors. For in vitro studies, we chose to use a 3D model: the spheroid (MCTS - MultiCellular Tumor Spheroid). This model has similar characteristics to the in vivo model thanks to its spheroidal organization. The spheroids have indeed gradients of oxygen penetration, nutrients and cell proliferation. The first part of the thesis concerns the identification and quantification of the species generated in PAM. The analytical methods used are paramagnetic electronic resonance, fluorimetry, colorimetry, liquid chromatography and mass spectrometry. These analyses revealed that the toxicity of PAM was due to several factors: on the one hand to the generation of ROS and RNS and on the other hand to the degradation of cell nutrients contained in the medium via, for example, the oxidation and nitrosylation of the amino acids. The second part is dedicated to the study of the effects of PAM on HCT-116 (colon cancer) spheroids[...]
Collaudin, Bernard. "Stabilisation d'hydrogène atomique polarisé en champ magnétique intense (B [inférieur ou égal à] 14 T)." Grenoble 1, 1986. http://www.theses.fr/1986GRE10059.
Full textMallardeau, Catherine. "L'hydrogène atomique polarisé : interaction avec les films d'Helium : expérience de compression." Paris 6, 1986. http://www.theses.fr/1986PA066186.
Full text