Дисертації з теми "Cinétique et mécanistique"
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Buffard, Aude. "Synthèse et étude mécanistique de nanocristaux d'InP et formation d'hétérostructures." Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066295.
Повний текст джерелаThis manuscript focuses on the synthesis of InP nanocrystals, their understanding of the mechanisms and the improvement of the optical properties of these objects. The nanocrystals of InP are promising materials for optoelectronic and biomedical applications due to their low toxicity and wide reachable spectral range. However, the synthesis of these nanoparticles is poorly controlled and does not allow to obtain large objects with optical properties comparable to CdSe nanocrystals. The phosphorus precursor commonly used presents a high toxicity and a high cost. The aminophosphine are phosphorus precursors of choice to replace the current one since it has a reduced toxicity and a low cost. A study of different synthesis parameters enabled to highlight the role of some reagents such as primary amines. Through a detailed mechanistic and kinetic study, the understanding of the reactions allows to improve the quality of the synthesized nanocrystals. In order to improve the optical qualities of the synthesized nanocrystals, heterostructures can be formed. InP/ZnS systems allow an increase in fluorescence. However, the deposition material is low. With a view to improve their fluorescence, hybrid heterostructure has been developed. This was developed on nanoplatelets CdSe/CdS as a template. The nanocrystals are surrounded by silica and gold layers which provide good protection concerning the environmental medium. The coupling between the plasmon of the gold and the fluorescence increases the optical properties of the material
Ruyffelaere, Fanny. "Etude mécanistique et cinétique de la dégradation oxydante des molécules parfumantes." Lille 1, 2005. http://www.theses.fr/2005LIL10154.
Повний текст джерелаPerfumes degradation is a problem of major concern in the perfumery industry because it is responsible for the loss of the odoriferous properties. The aim of this study was to identify the main chemical and photochemical processes, which result in the oxidative degradation of perfumed molecules. The first part was dedicated to the determination of the reactivity of perfumed molecules towards singlet oxygen(1O2) by measuring their global reactivity constants (kr + kq) by resorting to flash photolysis. The photosensitizing properties of dyes commonly used in perfumed composition were also assessed. The second part focuses on the interest of the oxidation potential as an oxidability index for the perfumed molecules. The third part deals with the elucidation of the aldehydes degradation mechanism in a silicone based complex matrix. The last part aimed at determining the antioxidant properties of phenolic perfumed molecules
Buffard, Aude. "Synthèse et étude mécanistique de nanocristaux d'InP et formation d'hétérostructures." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066295/document.
Повний текст джерелаThis manuscript focuses on the synthesis of InP nanocrystals, their understanding of the mechanisms and the improvement of the optical properties of these objects. The nanocrystals of InP are promising materials for optoelectronic and biomedical applications due to their low toxicity and wide reachable spectral range. However, the synthesis of these nanoparticles is poorly controlled and does not allow to obtain large objects with optical properties comparable to CdSe nanocrystals. The phosphorus precursor commonly used presents a high toxicity and a high cost. The aminophosphine are phosphorus precursors of choice to replace the current one since it has a reduced toxicity and a low cost. A study of different synthesis parameters enabled to highlight the role of some reagents such as primary amines. Through a detailed mechanistic and kinetic study, the understanding of the reactions allows to improve the quality of the synthesized nanocrystals. In order to improve the optical qualities of the synthesized nanocrystals, heterostructures can be formed. InP/ZnS systems allow an increase in fluorescence. However, the deposition material is low. With a view to improve their fluorescence, hybrid heterostructure has been developed. This was developed on nanoplatelets CdSe/CdS as a template. The nanocrystals are surrounded by silica and gold layers which provide good protection concerning the environmental medium. The coupling between the plasmon of the gold and the fluorescence increases the optical properties of the material
El, masri Ahmad. "Étude cinétique et mécanistique de la réactivité des composés organophosphorés avec les photooxydants atmosphériques." Thesis, Reims, 2014. http://www.theses.fr/2014REIMS026/document.
Повний текст джерелаThis thesis establishes the mechanism of heterogeneous degradation of chlorpyrifos (CLP) towards OH-radicals and ozone for CLP on quartz plaques and towards ozone for various contaminations of sand with CLP. The kinetic constants of the heterogeneous degradation are determined in a photo-chemical reactor coupled with a GC/MS. The chlorpyriphos-oxon (CLPO) and the trichloropyridinol (TCP) are the degradation products in the heterogeneous phase for different oxidizer and medium. The heterogeneous reactivity of CLPO towards ozone and OH-radicals are also studied. The results show that the OH-radicals constitute the main pathway of heterogeneous degradation of the CLP and that the CLPO is more persistent than the CLP. The CLPO can be transported far from its point of application. The heterogeneous ozonolysis of the CLP on sand shows that the kinetics are dependent of the contamination in CLP with an exponential behavior.The mechanism established from the analysis of products detected in the condensed phase plans the formation of small organophosphate molecules transferred in the gas phase. We studied the reactivity of two volatile organophosphate molecules the O,O,O-triethylphosphate (TEP) and the O,O-diethylethylphosphonate (DEEP) towards OH-radicals and towards the atomic chlorine in gas phase as a function of the temperature. The TEP and the DEEP present rate constants above 10-10 cm3.molecule-1.s-1. These molecules thus quickly degrade in the atmosphere and are source of a local photochemical pollution.Finally, to complete the degradation pattern of the CLP, its gas phase UV spectra is measured and its constant of photolysis is determined to 1,8 10-5 s-1, involving a photolysis life time of around 16 hours
Darwich, Chaza. "Définition et modélisation d'un procédé de synthèse de la N-aminopipéridine en régime continu : cinétique, mécanistique et extraction." Lyon 1, 2005. http://www.theses.fr/2005LYO10029.
Повний текст джерелаWafo. "Déchloration catalytique des PCB (polychlorobiphényles) : optimisation et approche mécanistique de la réaction." Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11032.
Повний текст джерелаToppi, Stéphanie. "Étude mécanistique et cinétique de la réaction d'hydrodésalkylation d'alkylaromatiques dans les conditions du reformage catalytique." Paris 6, 2002. http://www.theses.fr/2002PA066355.
Повний текст джерелаBesson, Blondel Caroline. "Etude cinétique et mécanistique en liquéfaction directe du charbon : Impact des conditions opéartoires et dusolvant donneur d'hydrogène." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10191/document.
Повний текст джерелаThis work deals with the understanding and the modeling of coal hydroliquefaction mechanisms, more precisely the impact of operating conditions and H-donor solvent -hydrogen gas phase-catalyst interactions. Experimental tests are performed in a batch reactor by using Illinois #6 coal, tetralin and NiMo/Al2O3 catalyst. An original separation procedure is developped, combinig micor-distillation and solvent extraction. Complete mass balances allow the dtermination of conversion, product yields and product quality. Operating conditions studied are temperature (380° C-420°C), hdrogen pressure (16-22 MPa) and NiMo/Al2O3 presence. Temperatures mainly impacts the firs stage of liquefaction (also called dissolution), hydrogne pressure and catalyst the products quality. Then, tests performed with other solvents (n-undecan or diethylbenzene) and/or under N2 pressure have shown the crucial impact of solvent on the first stage of liquefaction, and and the high impact of gas phase o products quality. These experimental results allow the establishment of kinetic model. In a first step, maceral are transformed into coke, preasphaltenes and hydrotreatment products. Coke formation only depends on temperature. However, preasphaltenes and hydrotreatment products formation highly depends on solvent. Other products (asphaltenes, vacuum distillate, middle distillate, light distillate and gas) are producted from preasphaltenes
Molinet, Josiane. "Oxydation de la monométhylhydrazine en milieux strictement monophasiques : conception des dispositifs expérimentaux : approche cinétique et mécanistique." Lyon 1, 1997. http://www.theses.fr/1997LYO10098.
Повний текст джерелаFouqueau, Axel. "Réactivité des terpènes avec le radical nitrate : études cinétique et mécanistique en chambres de simulation atmosphérique." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC0015.
Повний текст джерелаBiogenic volatile organic compounds (BVOC) are strongly emitted by forests and crops in the atmosphere. They are very reactive towards nitrate radical, the main tropospheric oxidant during the night, and play a key role in atmospheric chemistry. These reactions lead to the formation of a variety of functionalized products (organic nitrates, carbonyl compounds ...) and to large amounts of secondary organic aerosols. Organic nitrates are the main nitrogen oxides reservoir. They directly influence reactive nitrogen and ozone budgets. Secondary organic aerosol has direct and indirect impacts on climate, due to its formation, its optical and hygroscopic properties and its chemical composition. The aim of this work is to understand these processes at the molecular scale, through kinetic and mechanistic studies of NO3 radical oxidation of several BVOCs.Kinetic and mechanistic studies have been performed for three monoterpenes ((C10H16), γ- and α-terpinene and terpinolene) and one sesquiterpene ((C15H24), β-caryophyllene) in atmospheric simulation chambers. These compounds have been chosen to highlight the influence of their chemical structures on their reactivities and to fill the lack of experimental data about their chemistry in the literature.For the kinetic part, rate constants have been measured with both relative and absolute methods. Due to their high reactivities, this study has requiered the development on the simulation chamber of an IBB-CEAS ((Incoherent Broad Band Cavity Enhanced Absorption Spectroscopy) analysis pathway to measure nitrate radical at the ppt level. Mechanistic studies have been also conducted to identify and quantify the main reaction products. Organic nitrates and SOA yields have been calculated. Detected products allowed proposing reaction mechanisms
Soulière, Marie. "Caractérisation cinétique et mécanistique d'enzymes viraux impliqués dans la synthèse et la dégradation de la structure coiffe des ARN messagers." Thèse, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/4307.
Повний текст джерелаGoutelle, Véronique. "Synthèse de la 2-hydroxyéthylhydrazine par voie chloramine et par alkylation de l'(hydrate d'hydrazine) : mécanistique, modélisation cinétique et optimisation." Lyon 1, 2006. http://www.theses.fr/2006LYO10273.
Повний текст джерелаThis work was carried out with ISOCHEM (SNPE company). It presents various access roads to the synthesis of hydroxyethylhydrazine. This molecule arouses today a great interest taking into account its applications in the field aerospace, Defense, pharmaceutical and cosmetics industry. - The 1st part is devoted to the Raschig way. A kinetic and mechanistic study of the reactions of formation and degradation made it possible to identify the products and to establish a model. The optimum conditions for synthesis were defined as well as an approach of the operations of extraction. - The 2nd part relates to the alkylation of hydrazine hydrate by chloroethanol with and without the presence of a strong base. The rates laws of the mono and dialkylation relating to each option were given. This work was supplemented by a calorimetric study of the enthalpy of solvation and reaction. A total modeling makes it possible to control the whole of the reactional entities (ethylene oxide…)
Estève, Williams. "Réactivité des hydrocarbures aromatiques polycycliques (HAP) adsorbés sur des particules carbonées d'intérêt atmosphérique : développements analytique, cinétique et mécanistique." Bordeaux 1, 2002. http://www.theses.fr/2002BOR12636.
Повний текст джерелаPantazidis, Amalia. "Déshydrogénation oxydante du propane sur catalyseurs VMgO : optimisation du solide, étude mécanistique et cinétique, application en réacteur à membrane." Lyon 1, 1996. http://www.theses.fr/1996LYO10229.
Повний текст джерелаDe, Sousa Sozinho Tiago. "Etude mécanistique et cinétique des réactions de craquage dans les conditions d'isomérisation de la coupe C8 aromatique sur catalyseur bifonctionnel." Poitiers, 2010. http://www.theses.fr/2010POIT2278.
Повний текст джерелаThe aim of this thesis is to identify and to better understand the catalytic phases responsible for the naphthenic ring opening RO reactions and associated mechanisms during aromatic C8 isomerisation. In this reaction the main purpose is to maximize the p-xylene production starting from a mixture of the three xylene isomers (para-, ortho- and meta-) and ethylbenzene. The naphthenic RO losses constitute a p-xylene loss that is essential to minimise. Isomerisation bifunctional catalyst is constituted of a metal phase (platinum) supported on chlorinated alumina and a acidic zeolitic phase. In this study each catalyst active phase (platinum, chlorinated alumina and EU-1 zeolite) was studied separately over a model molecule. Then, all active phases were assembled to study the impact of the presence of two and three active phases, by means of model catalysts. Ethylcyclohexane, a direct product of the ethylbenzene hydrogenation and the first naphthene formed during isomerisation process was used as model molecule. Catalytic results show that ring opening reaction can be realized by pure metallic phase and at lower extent on a pure acidic phase. On bifunctional catatyst Pt-Alumina-zeolite, naphtenic RO is governed by bifunctional catalysis. This works allows to highlight the importance of hydrogenate sites / acid sites ratio during the complex scheme within the isomerisation reactions. Zeolite is mainly responsible for RO and cracking reactions in a bifunctional mechanism. Nevertheless, when hydrogenation sites become predominant, regarding acid sites, the reaction scheme switches to a metallic mechanism. External passivation of zeolite crystals was shown to be a potential way for improving catalytic selectivity and limiting RO
El-rachidi, Mariam. "Étude cinétique et mécanistique des réactions hétérogènes du folpel et du dimethomorphe avec l'ozone et les radicaux OH. Photooxydation homogène des composés morpholiniques avec les radicaux OH." Thesis, Reims, 2012. http://www.theses.fr/2012REIMS011.
Повний текст джерелаThe research study discussed in this thesis concerns the determination of the kinetic rate constants of the heterogeneous degradation of pesticides folpet and dimethomorph by ozone and OH-radicals using the technique of a simulation chamber coupled to a GC/MS analytical system. The study also involves the identification of the degradation products of the analyzed compound in the condensed phase using SPME/GC/MS. The heterogeneous OH and O3-reactivities of the identified degradation product of dimethomorph, (4-chlorophenyl)(3,4-dimethoxyphenyl)methanone (CPMPM), are also evaluated experimentally. The obtained results show that the rate constant values of the analytes are in the order of 10-20-10-19 and 10-14-10-12 cm3.molecule-1.s-1 relative to heterogeneous O3 and OH-oxidation, respectively. Such values implicate tropospheric life-times that vary from a few days to several months, meaning that these compounds are relatively persistent and may be transported to regions far from their point of application.The UV-absorption spectra and homogeneous OH-reactivities of the expected degradation product of dimethomorph in the gas phase, N-formylmorpholine (NFM), and two other gaseous compounds, morpholine and N-acetylmorpholne (NAM) are also studied. The results show that these compounds are not susceptible to photolysis in the atmosphere and that they exhibit strong reactivity towards OH-radicals. Generally speaking, their atmospheric life-times are in the order of a few hours and thus they are non-persistent
Dupont, Nicolas. "Vaporeformage du methanol en gaz de synthèse et oxydation partielle en formaldehyde : approche mécanistique, étude cinétique et mise en oeuvre de réacteurs micro-structures." Lyon 1, 2007. http://www.theses.fr/2007LYO10077.
Повний текст джерелаThe increasing use of biomass and biofuels will lead to new and promising processes and intensified use of methanol in case of innovating reactors that are efficient, small and above all cheap. A catalytic micro-structured reactor (design and coating) was developed, evaluated and compared with a fixed bed reactor. Some tremendous advantages were pointed out such as low The increasing use of biomass and biofuels will lead to new and promising processes and intensified use of methanol in case of innovating reactors that are efficient, small and above all cheap. A catalytic micro-structured reactor (design and coating) was developed, evaluated and compared with a fixed bed reactor. Some tremendous advantages were pointed out such as low ΔP, very good temperature control and to be adapted tool to study the kinetics of the methanol steam reforming. The use of micro-structured reactors for the methanol partial oxidation permits for a manufacturer of formaldehyde polymeric derivatives to produce its own formaldehyde according to its need (reduction of storage cost and less monomer stabilization problems). Development and engineering of those reactors was studied. Moreover, the reaction and the positive role of water on the selective conversion were investigated in detail for silver based catalysts, by comparing fixed bed and micro-structured configurations
Loaiza, Ambuludi Silvia, and Ambuludi Silvia Loaiza. "Étude des propriétés physiques et du comportement mécanique des Basaltes : étude cinétique, mécanistique et toxicologique de l'oxydation dégradante de l'Ibuprofène par l'oxydation avancée électrochimique et photochimique." Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00807532.
Повний текст джерелаLoaiza, Ambuludi Silvia. "Étude des propriétés physiques et du comportement mécanique des Basaltes : étude cinétique, mécanistique et toxicologique de l'oxydation dégradante de l'Ibuprofène par l'oxydation avancée électrochimique et photochimique." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1145/document.
Повний текст джерелаThe first part of this thesis is focused on the remediation of waters contaminated with persistent organic pollutants, in particular pharmaceutical products. Alternative technologies such as the advanced oxidation processes (AOPs), which based on the generation of hydroxyl radicals OH, were applied to the degradation and/or mineralization of a pollutant drug, ibuprofen, in aqueous medium. We chose this pollutant as a model molecule to study due to its large volume of prescription and to its proved presence in the effluents of sewage plants and natural waters. The main objective of this work was the optimization of operational parameters of the applied AOPs. The concentration of H2O2 and Fe2+ reagents ratio to generate hydroxyl radicals for photo-Fenton process, and supporting electrolyte concentration (and the nature) and the applied current for both electro-Fenton and anodic oxidation processes. The oxidation and mineralization kinetics of the ibuprofen were studied and the absolute rate constant for the oxidative degradation of ibuprofen was determined by the competition kinetic method, being 3,84 109 M-1s-1. Toxicity tests of the drug solutions during the anodic oxidation process were carried out by the Microtox method. Our results show that these methods are effective for the degradation of this pharmaceutical product from water. Ibuprofen was completely degraded and the organic matter was almost completely mineralized after the application of these processes. The second part of the thesis includes an experimental study of the physical properties (at different scales) and the mechanical behavior of basaltic rocks. We studied the mechanical behavior and the failure modes of a porous basalt from Azores. Results were acquired under triaxial compression experiments on water saturated samples at room temperature. This basalt presented two modes of deformation. At low confining pressure, the samples exhibited a brittle mechanical behavior and a localized deformation (shear band). For higher confining pressure, this basalt showed a ductile behavior and localized compactions (compaction bands). The mechanical data allows us to plot the full yield surface for the porous basalt. The quantification of the physical properties of two types of basalts from the Galapagos was performed at room temperature and pressure. In order to study the effect of cracking on the physical properties of these basalts, samples were subjected to thermal treatments to induce thermal crack damage. Finally for the less porous basalt, measures of wave velocities under the pressure at which it is subjected in depth were acquired. The obtained results and the following application of models with them allow quantifying the density of initial cracks and of those induced by thermal treatments, as well as quantifying the aspect ratio of cracks. The studied physical properties led to better understand the role of the pore network of the rock in these physical properties. This laboratory study was necessary for the interpretation of data collected in situ by seismic refraction method
Daniel, Cécile. "Synthèse du carbonate de diméthyle par carboxylation du méthanol catalysée par des oxydes mixtes de cérium et de zirconium : relation structure–activité, étude mécanistique et cinétique." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1022.
Повний текст джерелаDimethylcarbonate (DMC) is used in polymer synthesis as well as a fuel additive and solvent. The current industrial DMC production is a polluting and hazardous process. On the other hand, the direct carboxylation of methanol with CO2 is a green route to DMC. However, this reaction is highly limited by thermodynamics, limiting the conversion to less than 1%. The integration of a catalyst in a catalytic membrane reactor for water and DMC removal, would shift the equilibrium conversion thereby improving the DMC yield. The aim of this thesis is to develop and study highly active catalysts for DMC synthesis. This manuscript covers: (i) catalyst screening (ii) a structure-activity relationship study (iii) a mechanistic approach and (iv) a kinetic study. A protocol to measure the activity at low conversion has been developed. Catalyst screening evidenced solid solutions of ceria/zirconia (CZ) as the most active and selective. Flame sprayed pyrolysis ceria/zirconia are one order of magnitude more active than coprecipitated CZ. Interestingly, structural and textural features like crystalline and porous structure were similar regardless of the activity. Nevertheless, the activity could be correlated to the nature and the density of the methoxides and carbonates surface species. The mechanism was refined by isotopic exchange and DRIFT experiments. A kinetic study was performed in a batch reactor that integrated the physical equilibria of the gas-expanded reacting mixture
Chupin, Cédric. "Réduction sélective du monoxyde d'azote par le méthane en présence d'oxygène sur Co-ZSM-5 et Fe-ZSM-5 : optimisation des catalyseurs, étude mécanistique et cinétique de la réaction." Lyon 1, 2001. http://www.theses.fr/2001LYO10236.
Повний текст джерелаTeh, Siew Pheng. "Purification de l'hydrogène par l'oxydation préférentielle du monoxyde de carbone pour une application pile à combustible : développement de catalyseurs supportés sur monolithe, étude mécanistique et cinétique." Lyon 1, 2005. http://www.theses.fr/2005LYO10024.
Повний текст джерелаDirany, Ahmad. "Études cinétique et mécanistique d'oxydation/minéralisation des antibiotiques sulfaméthoxazole (SMX), amoxicilline (AMX) et sulfachloropyridazine (SPC) en milieux aqueux par procédés électrochimiques d'oxydation avancée : mesure et suivi d'évolution de la toxicité lors du traitement." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00582963.
Повний текст джерелаRosny, Eve de. "Nouvelles séries d'inhibiteurs peptidiques et non peptidiques de la protéase du VIH-1 : études cinétiques et mécanistiques." Marne-la-Vallée, 1997. http://www.theses.fr/1997MARN0011.
Повний текст джерелаKobl, Kilian. "Aspects mécanistiques et cinétiques de la production catalytique de méthanol à partir de CO2/H2." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF023/document.
Повний текст джерелаIn view of the climate change and the energy transition, this work is part of the ANR project VItESSE2 about renewable electric energy storage and CO2 valorization by methanol hydrogenation on copper catalysts. During this thesis, an analytical method for copper surface measurement by N2O chemisorption was developed. Based on catalytic tests at 50 bar, kinetic models for Cu/ZnO/Al2O3 and Cu/ZnO/ZrO2 catalysts were elaborated. For the study of the mechanism, a diffuse reflection infrared setup was developed in order to study different catalysts for methanol synthesis and water-gas shift reaction. The setup was used for in situ catalytic tests at 34 bar under reaction flow. The study was complemented by temperature programmed desorption experiments with different probe molecules. The results suggest that the Cu/ZnO/ZrO2 catalyst is more selective for methanol than Cu/ZnO/Al2O3 and that a preparation method which favors Cu–ZnO–ZrO2 interactions can be beneficial for catalytic activity
Remontet-Dugenest, Stéphanie. "Mâchefers d'incinération d'ordures ménagères : caractérisation physico-chimique de la matière organique : études cinétiques et mécanistiques." Lyon 1, 1997. http://www.theses.fr/1997LYO10366.
Повний текст джерелаRoux, Céline. "Aspects structuraux, mécanistiques et thérapeutiques de phosphomannose isomérases de type I et II : synthèse et études cinétiques de nouveaux inhibiteurs." Paris 11, 2005. http://www.theses.fr/2005PA112320.
Повний текст джерелаPhosphomannose isomerases (PMI) are metalloenzymes catalyzing the reversible isomerization of mannose-6-phosphate to fructose-6-phosphate. These enzymes, classified into three types according to their sequence and their physico-chemical properties, are essential for the survival and the proliferation of many microorganisms. The low sequence homology between bacterial, like Pseudomonas aeruginosa, and human enzymes suggest PMI as potential therapeutic targets. Nevertheless, crystallographic and inhibition studies were largely unexplored at the beginning of this work. So, elucidation of PMI's catalytic mechanism appears as a main goal. For this reason, in addition to research of new PMI activity tests, synthesis and kinetic studies of new potential inhibitors were investigated, as well as polarizable molecular mechanics and quantum mechanics studies of Candida albicans PMI. All the results allowed us to propose the first catalytic mechanism for the PMI-catalyzed reaction, underlying critical points: (i) the metallic cofactor of the active site would play an important role in the recognition and the stabilization of the substrate, as well as it would play a catalytic role as Lewis acid, (ii) the phosphate moiety in a secondary role would be essential for the molecule docking at the active site of the enzyme, and finally (iii) deprotonation of the substrate would imply a catalytic triade metal-Glu-Lys where the catalytic base would be the neutral lysine
Ahmad, Lama. "Inhibiteurs à visée thérapeutique de la phosphomannose isomérase de Candida albicans et du facteur de motilité autocrine : études cinétiques, structurales, mécanistiques et diagnostiques." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS459/document.
Повний текст джерелаPhosphoglucose isomerase (PGI) and type I phosphomannose isomerase (PMI), a zinc metalloenzyme, catalyze the reversible isomerization of β-D-fructose 6-phosphate (F6P) to α-D-glucose 6-phosphate (G6P) and β-D-mannose 6-phosphate (M6P), respectively. These two enzymes are potential therapeutic targets. Human PGI (hPGI) often called as AMF-PGI (autocrine motility factor-PGI), in addition to its intracellular glycolytic activity, stimulates cell migration in vitro and metastasis in vivo. Inhibition of its extracellular activity is obviously interesting in oncology. On the other hand, Candida albicans is the main yeast involved in human pathology. During recent years, resistance of this pathogenic fungus to conventional antifungal drugs appeared. Consequently, research is moving towards new therapeutic targets, including C. albicans PMI (CaPMI) that plays an important role in the biosynthesis of mannosylated structures required for pathogen survival. The reactions catalyzed by these two enzymes involve the same high energy intermediate (HEI) type 1,2-cis-enediolate, except that it is coordinated to the zinc active site in the case of PMI. Overexpression and purification of both CaPMI and hPGI were performed in our laboratory. A small chemical library was created from the synthon 5-phospho-D-arabinono-1,4-lactone (5-PAL) by modulating the head part of the HEI. A zinc binding group (ZBG) was introduced in several compounds in order to selectively inhibit the CaPMI enzyme. Moreover, two compounds with a terminal amine function were designed to selectively inhibit hPGI by targeting a glutamate residue of the enzyme (Glu357). All these molecules were first tested on rabbit muscle PGI and PMI from E. coli, and later on CaPMI and hPGI. None of these compounds are good inhibitors of CaPMI. However, a series of strong inhibitors of hPGI, and therefore potentially anti-metastatic drugs, was discovered. High-resolved 3D structures of the two enzymes complexed with inhibitors have been successfully obtained. Beyond the therapeutic, mechanistic and structural aspects, an electrochemical biosensor based on one of the synthesized inhibitors was carried out for the detection of hPGI, which is a validated biomarker of metastatic cancers. This biosensor demonstrated a detection limit of 43 fM in phosphate buffer (PBS)
Doussin, Jean-Francois. "Etudes cinétiques et mécanistiques des processus d'oxydation des composés organiques volatils d'importance atmosphérique induits par le radical nitrate en atmosphères simulées." Phd thesis, Université Paris-Diderot - Paris VII, 1998. http://tel.archives-ouvertes.fr/tel-00002792.
Повний текст джерелаAzrague, Kamal. "Couplage entre photochimie et membrane pour la dépollution d'eaux turbides : mise au point d'un photoréacteur à membrane et étude cinétique et mécanistisque de la dégradation de polluants organiques." Toulouse 3, 2005. http://www.theses.fr/2005TOU30230.
Повний текст джерелаThis work was carried out in the field of the depollution of turbid water by an original method combining membranes and photochemistry processes. Two types of photoreactor with membrane were developed, one using the photocatalysis (irradiation of a semiconductor: TiO2), the other using V-UV photolysis process (V-UV: irradiation at 172 nm wavelenght). The advantage of these hybrid water and processes is that they can be applied to the depollution of limpid water, but also of turbid water and even of muds in aqueous suspension. For this study, the polluant models selected is the 2,4-dihydroxybenzoic acid (DHBA), contaminant agent resulting from the oxidation of the salisylic acid. The mineralisation of this compound was obtained for all photochemical processes used. The evolution of the various intermidiates formed during degradation was followed by various complementary analytical methods (UV-visible spectroscopy, GC, HPLC, HPLC/MS, TOC measurements). This study allows highlighting a different mechanism for the photocatalysis and V-UV photolysis. Indeed, in photocatalysis this compound reacts exclusively with the positive holes (h+) formed on the photocatalysor wheareas in V-UV photolysis an original mechanism of degradation of the DHBA implying only the hydroxyl radicals has been proved. Moreover, starting from the kinetics of mass transfer and degradation of the DHBA, it was possible to estabilish very good mathematical models describing the evolution of the pollutant in all compartments of the process. These models will allow, in an immediate future, to the dimensioning of pilot units
Lopez, Olivier. "Aspects mécanistiques de la réaction de précipitation de la calcite et mouvements de fluide supercritique dans une matrice calcitique : implications au stockage minéral du C02." Paris, Institut de physique du globe, 2006. http://www.theses.fr/2006GLOB0018.
Повний текст джерелаDirany, Ahmad. "Études cinétiques et mécanistique d'oxydation/minéralisation des antibiotiques sulfaméthoxazole (SMX), amoxicilline (AMX) et sulfachloropyridazine (SPC) en milieux aqueux par procédés électrochimiques d'oxydation avancée. Mesure et suivi d'évolution de la toxicité lors du traitement." Phd thesis, Université de Marne la Vallée, 2010. http://tel.archives-ouvertes.fr/tel-00740119.
Повний текст джерелаHajj, 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 джерелаThe 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 »
Fakih, Mariam. "Réactivité atmosphérique des principaux produits d'oxydation de première génération des monoterpènes." Electronic Thesis or Diss., Reims, 2024. http://www.theses.fr/2024REIMS010.
Повний текст джерелаMonoterpenes are biogenic volatile organic compounds (BVOCs) widely emitted into the atmosphere by forests and plant crops, thus representing significant players in atmospheric chemistry. Their high reactivity towards atmospheric oxidants has been the subject of several studies in the literature. However, their first-generation oxidation products are less evaluated, and could partly explain the missing reactivity and the underestimation of AOS formation by models. In this context, this study aims to understand the atmospheric reactivity of five VOCBs (nopinone, myrtenal, ketolimonene, caronaldehyde, and limononaldehyde) that are first-generation oxidation products of α- and β-pinene and limonene. This work focuses on the study of degradation processes by determining the kinetics and mechanism of oxidation reactions of the targeted BVOCs by the OH radical, chlorine and ozone, as well as their potential photolysis through the study of their UV-Vis absorption spectra. To this end, the oxidation reactions of five first-generation monoterpene oxidation products were studied in an atmospheric simulation chamber coupled with various analytical techniques (FTIR, SPME-GC/MS, PTR-MS-ToF).The spectroscopic study focused on determining the UV-visible absorption spectra of the five compounds in the 200-400 nm range at a temperature of 353 ± 2 K, and at a pressure below the saturation vapor pressure of COVB. The spectra show a broad absorption band between 240 and 370 nm, corresponding to the n-π* band of the carbonyl group. The significant absorption of these compounds above 290 nm suggests that they are likely to be removed by photolysis in at least a few hours.The temperature kinetic studies carried out in this thesis concern the (VOC+ OH) reaction for nopinone, myrtenal, ketolimonene and limononaldehdye, the (VOC + Cl) reaction for nopinone, myrtenal and ketolimonene and the ozonolysis reaction for ketolimonene, myrtenal and limononaldehyde. Experiments were carried out using either the relative or the absolute kinetic method in the temperature range 298 - 353 K and at atmospheric pressure. The kinetic results obtained made it possible to calculate the atmospheric lifetimes of these compounds. Their atmospheric persistence does not exceed one day. Overall, these lifetimes show that the main route of elimination for the compounds studied is through their reaction with OH radicals, with significant competition in coastal regions from Cl radicals. The study also revealed a generally positive trend for OH radicals and ozone with increasing temperature, and a negative trend for chlorine.Finally, mechanistic ozonolysis studies of ketolimonene, myrtenal and limononaldehyde were carried out. These studies consist of monitoring the temporal evolution of the reagents as well as the reaction product. These data allowed us to extract the formation rate of the products formed during ozonolysis processes. Based on these results, reaction mechanisms of ozonolysis of ketolimonene, myrtenal and limononaldehyde are proposed
Halim, Dany. "Expression et étude mécanistique et d'inhibition de la transglutaminase et de la y-glutamyltranspeptidase." Thesis, 2006. http://hdl.handle.net/1866/17980.
Повний текст джерелаEl-Rachidi, Mariam. "Étude cinétique et mécanistique des réactions hétérogènes du folpel et du dimethomorphe avec l'ozone et les radicaux OH. Photooxydation homogène des composés morpholiniques avec les radicaux OH." Thesis, 2012. http://www.theses.fr/2012REIMS011/document.
Повний текст джерелаThe research study discussed in this thesis concerns the determination of the kinetic rate constants of the heterogeneous degradation of pesticides folpet and dimethomorph by ozone and OH-radicals using the technique of a simulation chamber coupled to a GC/MS analytical system. The study also involves the identification of the degradation products of the analyzed compound in the condensed phase using SPME/GC/MS. The heterogeneous OH and O3-reactivities of the identified degradation product of dimethomorph, (4-chlorophenyl)(3,4-dimethoxyphenyl)methanone (CPMPM), are also evaluated experimentally. The obtained results show that the rate constant values of the analytes are in the order of 10-20-10-19 and 10-14-10-12 cm3.molecule-1.s-1 relative to heterogeneous O3 and OH-oxidation, respectively. Such values implicate tropospheric life-times that vary from a few days to several months, meaning that these compounds are relatively persistent and may be transported to regions far from their point of application.The UV-absorption spectra and homogeneous OH-reactivities of the expected degradation product of dimethomorph in the gas phase, N-formylmorpholine (NFM), and two other gaseous compounds, morpholine and N-acetylmorpholne (NAM) are also studied. The results show that these compounds are not susceptible to photolysis in the atmosphere and that they exhibit strong reactivity towards OH-radicals. Generally speaking, their atmospheric life-times are in the order of a few hours and thus they are non-persistent
Lapointe, Sébastien. "Complexes cationiques POCOP de nickel : synthèse, caractérisation, réactivité et étude catalytique." Thèse, 2016. http://hdl.handle.net/1866/16085.
Повний текст джерелаThis thesis describes the chemistry of nickel (II) cationic pincer complexes bearing a POCOP ligand. The content is divided into two parts. The first part (chapter 2) concerns the synthesis, characterization and reactivities of nickel (II) cationic POCOP pincer complexes with an acetonitrile ligand coordinated to the metal center via the nitrile moiety, [(R-POCOPR’)Ni(NCMe)][OSO2CF3] where R is a ring substituent and R’ is a P-substituent (R’ = iPr : R = H (1), p-Me(2), p-OMe(3), p-CO2Me(4), p-Br(5), m,m-tBu2(6), m-OMe(7), m-CO2Me(8); R’ = t-Bu : R = H (9), p-CO2Me(10)). The cationic complexes are synthetized by reacting the neutral nickel (II) bromide derivatives R-(POCOPR’)Ni-Br with Ag(OSO2CF3) in acetonitrile at room temperature. The impact of R and R’ groups of the POCOP ligand on the structure and electronic proprieties of the complexes has been studied by NMR, UV-Vis and IR spectroscopy, as well as by single crystal x-ray diffraction studies and cyclic voltammetry measurements. The observed ν(C≡N) values were found to increase with the increasing electron-withdrawing nature of R, i.e., in the order 7 < 3 ~ 2 ~ 6 < 1 < 5 ~ 8 < 4 and 9 < 10. This trend is consistent with the anticipation that enhanced electrophilicity of the nickel center should result in an increase in net MeCN→Ni σ-donation. It is also interesting to note that all cationic complexes show a much higher Ni(II)/Ni(III) oxidation potential than their neutral Ni-Br analogues. Following this, an equilibrium study is presented that shows the facile exchange of the MeCN/Br ligands between the charge-neutral and cationic complexes (R-POCOPR’)NiBr and [(R-POCOPR’)Ni(NCMe)][OSO2CF3]. The second part of this thesis consists of two chapters describing, respectively, structural studies that are relevant to our understanding of the mechanism of hydroamination reactions promoted by the title complexes (chapter 3), and reactivity and kinetic studies aimed at understanding the impact of different variables (R and R’; temperature; substrates; solvent; etc.) on the Michael-type hydroamination and hydroalkoxylation of acrylonitrile and its substituted derivatives (chapter 4). Chapter 3 will also discuss the attempted synthesis of new amine and nitrile POCOP cationic and neutral complexes, as well as the facile displacement of the amine moiety by a nitrile.