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Komla, Adéchion. "Etude de la texture de couches à propriétés optiques et catalytiques spécifiques obtenues à partir d'aciers inoxydables". Toulouse 3, 1991. http://www.theses.fr/1991TOU30277.
Pełny tekst źródłaWakim, Salem. "Elaboration de structures conjuguées chirales à partir de dérivés du trans (1R, 2R)-1,2-diaminocyclohexane. Evaluation des propriétés catalytiques et optiques". Montpellier 2, 2002. http://www.theses.fr/2002MON20018.
Pełny tekst źródłaSaitzek, Sébastien. "Systèmes multifonctionnels à base de dioxydes de cérium nanostructurés. Nanocomposites catalytiques CeO2-CuOx et bicouches CeO2-VO2 pour commutation en optoélectronique IR". Toulon, 2005. http://www.theses.fr/2005TOUL0014.
Pełny tekst źródłaCerium dioxide is known as presenting a large variety of physico-chemical properties: it can be considered as a multifunctional compound. We present two studies linked to two types of applications in which cerium dioxide is involved as a multifunctional phase: catalytic behaviours of nanocomposite systems CeO2- CuOx for gas sensor applications, optical responses and chemical stability of CeO2-VO2 bilayers for infrared applications. This last study is connected with new technologies like bolometric applications (IR camera). The first study consisted in preparing nanostructured systems CeO2-CuOx from low temperature routes (soft chemistry including sol-gel, low temperature processes). This nanocomposites were characterized from X-ray diffraction, electron microscopy techniques, BET analyses. Infrared spectroscopy associated with homemade equipment was then used to follow catalytic reactions in presence of gas mixtures (air-CH4 or air-CO). A modelling approach is presented to interpret the IR analyses and the catalytic site saturation, observed in the case of ceria based systems. The CuOx –ceria samples were then compacted and inserted in a homemade electronic system to analyse the influence of CO or CH4 reducing gases, on surface conduction of CuOx-CeO2 pellets. The results obtained from FTIR analyses and electronic measurements are found to be coherent: the copper additions decrease the durability of catalytic responses of these nanocomposite systems, however they increase the sensibility in the case of low Cu additions. This might be interesting for gas sensor applications. The second study deals with CeO2-VO2 bilayers obtained from sputtering techniques and deposited in Si and SiO2 substrates. RF sputtering parameters were optimised to deposit first VO2 then CeO2 thin layers. The role of CeO2 was to insure a protection of the VO2 layer from aggressive environments, without degrading optical responses. Starting from a low cost target of V2O5 , layers of VO2 were obtained. We show that these bilayers present a good thermochromic optical contrast (insulating-metal transition at 68°C). Ceria is known as being transparent for IR wavelengths and opaque for UV radiation. However, the emissivity depends on ceria layer thickness. These new bilayers present a double interest: they can present increased chemical stability (improvement of lifetimes), and they can be used to modulate infrared emissivity responses in the case of IR detection
Diaw, Abdou Karim Diagne. "Electrosynthèse, caractérisation et propriétés optique du Poly-N-phénylpyrrole dans divers milieux et sur divers substrats : étude de l'effet catalytique du pyrrole et de l'effet d'inhibition de corrosion : synthèse organique, électropolymérisation en milieu organique, caractérisation et propriétés optiques des dérivés p-substitués du poly(N-PhPy)". Paris 7, 2010. http://www.theses.fr/2010PA077014.
Pełny tekst źródłaTwo strategies are proposed to improve the organic polymer solubility for their use as active components in electronic devices: in the first one N-phenylpyrrole (N-PhPy) is electropolymerized in micellar solution, which increases solubility of resulting polymers; in the second one an electron-donating substituent is grafted in the para position of phenyl in N-PhPy moiety by chemical synthesis, followed by an electropolymerization process. A direct micellar medium (SDS + water + perchloric acid) and an inverse micellar medium (AOT + alcane (octane) + perchloric acid) are used to electrosynthesize poly(N-PhPy) films on Pt. These films present a good solubility, which also allowed us to characterize their structure by MALDI-TOF mass spectrometry, and to study their optic properties in organic solution. We were able to synthetize with satisfactory yields (36-81 %), by the Clauson-Kaas modified method and the Still method and to characterize a new series of N-PhPy para-substituted derivatives and new symmetrical and asymmetrical mono and oligophenylenethiophene compounds with one (or 2) pyrrole(s) at the chain end (ThPhPy and PyPhThThPhPy). We electrosynthesized in organic medium, very electroactive and adherent poly(MPhPy), poly(HPhPy), poly(ThPhPy), poly(PhDPy) and poly (DPhDPy) films on Pt. FT-IR spectroscopy showed the existence of a coupling in the a - a' positions of pyrrolic rings, having pendant phenyl groups with an electron-donating substituent in para. We compared the optic properties of these N-PhPy derivatives and of corresponding soluble polymers [poly(MPhPy), poly(HPhPy), poly(ThPhPy)] in organic solution and measured the fluorescence quantum yields and decays
Lee, Suyeon. "Synthesis and properties of mono and bi- metallic nanoparticles of noble metals; towards fabrication of novel functional nanoparticles assemblies". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS580.
Pełny tekst źródłaNoble metal nanoparticles (NPs) have attracted a great interest last years in various domains due to their distinct physical and chemical properties such as optical, catalytic or magnetic properties. In this thesis, we investigated the various approaches to integrate two metals in the same system, such as bimetallic nanoparticles, or binary superlattices to obtain new properties. We have developed seed-mediated growth method to rationally synthesis core-shell NPs Au(or Ag)@M (M=Ag, Pd, Pt). The impact of synthesis parameters such as concentration of metallic precursors, nature of ligands or temperature on key NPs parameters (core size, shell thickness, dispersity) was studied. The optical, vibrational and catalytic properties of different bimetallic NPs were characterized according to their structure, chemical composition, number of shell atomic layer and core crystallinities. In addition, binary NP superlattices, which are co-assembled from of two different complementary components were also reported. Several assembly conditions (effective size ratio, concentration ratio, deposition temperature, deposition method) were explored. The physical mechanism responsible for the observed structural variation was thus identified. A variety of crystalline structures for the binary superlattices such as AlB2, NaZn13, NaCl were produced. Finally, the magnetic properties of Fe2O3/Au NP binary superlattices were studied. They are determined by the interparticle distance of Fe2O3 NPs modulated by the insertion of Au NPs
El, Moll Hani. "Synthèses et propriétés catalytiques de cavitands résorcinaréniques". Strasbourg, 2009. http://www.theses.fr/2009STRA6118.
Pełny tekst źródłaPoriel, Cyril. "Les spirobifluorènylprophyrines : synthèse, électropolymérisation et propriétés catalytiques". Rennes 1, 2003. http://www.theses.fr/2003REN10102.
Pełny tekst źródłaAbu, Bakar Noor Hana Hanif. "Particules bimétalliques. Synthèse, caractérisation et propriétés catalytiques". Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10013/document.
Pełny tekst źródłaThe synthesis of PtNi bimetallic particles supported silica catalysts, prepared via non-classical methods using sodium borohydride (NaBH4) as a reducing agent, was studied in detail. The silica supports employed in this work is limited to crystalline silica and mesoporous aluminosilicate (MCM-41). Various preparation techniques as well as reduction parameters were investigated to gain an insight on how these factors influenced the final structure of the PtNi particles on the silica support and their catalytic reactivity towards the hydrogenation of benzene to cyclohexane. It was found that this reduction method enabled total reduction of the metal salts during the preparation stage of the catalysts. Hydrogen consumptions which were detected using H2-TPR analysis were mainly attributed to surface oxidation of the metal phase during storage. Studies on the effect of preparation techniques showed that the surface and catalytic properties of the catalysts are largely affected by the PtNi ratio as well as the method in which the metal salts are introduced onto the support. Catalysts prepared via co-impregnation technique generally exhibited better catalytic reactivity when compared to those prepared via co-precipitation and step-impregnation techniques. Further, catalysts with higher Ni content showed a tendency towards lower reactivity in contrast to those with high Pt content. Several catalysts demonstrated enhanced reactivity when compared to the monometallic Pt catalysts. Investigations showed that the improved reactivity can be attributed to alloying of the Pt and Ni accompanied by surface segregation of Pt. As a means to improve catalytic reactivity, PtNi stabilized oleic acid particles were synthesized prior to incorporation onto a silica support. The intention of this study is to allow better control of the dispersion and alloying between the PtNi particles. Results show that though better dispersed alloys were obtained, very low activity was observed. Nickel surface segregation is likely to be the cause of this due to the presence of oxygen from oleic acid. The effect of several reduction parameters was also investigated to enhance catalytic reactivity. The reduction temperature, NaBH4 concentration and medium in which reduction was carried out were varied. Variations in these parameters affected the particle morphology and dispersion of the PtNi particles. Optimum catalytic reactivity was obtained when small dispersed PtNi particles were formed at 273 K using 0.3 M NaBH4 in a medium of ethanol. Classical methods were also used for the synthesis of PtNi supported catalysts. In this study the PtNi particles were formed using H2 gas as the reducing agent. Several catalysts showed improved reactivity. Investigations show that this is attributed to the anchoring effect of Ni2+ ions which anchors Pt to the support, forming fine dispersed Pt particles available for catalytic reaction. In general, it is obvious that alloyed and non – alloyed bimetallic particles supported on silica can lead to the enhancement of hydrogenation reactions when compared to the respective monometallic catalysts. However, the PtNi ratios, preparation techniques, environment in which the particles are reduced and support influences the structure of the metallic phase of these catalysts. Therefore it is imperative to gain a thorough understanding on these parameters, in order to synthesize catalysts with desired properties
Ramos, Paul. "La lipase pancréatique humaine : Purification, propriétés catalytiques et propriétés de fluorescence". Université Louis Pasteur (Strasbourg) (1971-2008), 2002. http://www.theses.fr/2002STR13207.
Pełny tekst źródłaThis work of thesis is articulated around two parts. The first part describes the purification of human pancreatic lipase and the study of its catalytic properties. In a second part, more fundamental, the properties of fluorescence of human pancreatic lipase were studied. Lipase was purified starting from two origins: human pancreatic juice and recombinant human pancreatic lipase. The catalytic properties of the two purified enzymes were studied in titrimetry at constant pH. They were found identical to those of the enzyme present in the plasma of patients suffering from acute pancreatitis. Moreover, the stability of the two preparations of purified enzyme proved to be excellent. In addition, the two preparations are commutable with the specimens coming from patients. They were certified by five laboratories (ours having coordinated the study) from four different countries. These results and the batches of these two materials were transmitted to the Bureau Communautaire de Référence (Brussels) for recording. These two materials will improve the comparability of results of measurements of the enzymatic activity of lipase in fundamental and clinical enzymology studies. In the second part we carried out the studies in fluorescence of wild pancreatic lipase and various mutants where a tryptophan was replaced by a phenylalanine. Wild pancreatic lipase has three distinct lifetimes. Only the change of tryptophan 30 involved the disappearance of the longest lifetime thus characterizing the contribution of this tryptophan in the total fluorescence of protein. Tryptophan 30 is very close to the lid covering the catalytic site with lipase in closed conformation (non active). We can attribute the long lifetime to tryptophan 30, which gives a convenient tool to follow with fluorescence the structural and likely functional variations of this important part of the protein during its activation by biliary salts and colipase. The study of the fluorescence of lipase in the presence of colipase and/or biliary salts by following the long lifetime of protein showed significant differences compared to the characteristics of fluorescence of F30 lipase without any effector (closed conformation). This tool should allow to easily identify inactive and active conformation thanks to measurement of the long lifetime of human pancreatic lipase
Pinna, Nicola. "Nanomatériaux : étude structurale et propriétés optiques". Paris 6, 2001. http://www.theses.fr/2001PA066357.
Pełny tekst źródłaJean, Bruno. "Propriétés électriques, optiques et électro-optiques du semiconducteur CdIn2 Te4". Bordeaux 1, 1994. http://www.theses.fr/1994BOR10553.
Pełny tekst źródłaRat-Valdambrini, Micha. "Stabilité thermique et propriétés catalytiques des matériaux mésostructurés hybrides". Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26212/26212.pdf.
Pełny tekst źródłaHe, Zhongli. "Complexes hétérobimétalliques : synthèse et évaluation de leurs propriétés catalytiques". Toulouse 3, 1992. http://www.theses.fr/1992TOU30013.
Pełny tekst źródłaLe, Maréchal Jean-François. "Propriétés catalytiques et comportement dynamique de complexes de l'uranium". Paris 11, 1986. http://www.theses.fr/1986PA112023.
Pełny tekst źródłaWe studied the catalytic properties of organometallic uranium Ill and IV compounds in solution as well as reaction mecanisms. In the first part, we investigated the structure in solution of CpUCl₃L₂ (L=THF, HMPA, OPPh₃, OP(OR)₃). When L = HMPA, the complex exists in two isomers in equilibrium with the L ligands either in trans or mer-cis configuration. The isomerization (Ea = 92 kJ mol⁻¹) as well as the bimolecular exchange with an outer sphere ligand L are observable in ¹H and ³¹P NMR, and quantified with the spin saturation transfer technique in several solvents and at different temperatures between 230 and 330 K. We extended these properties to the other L ligands. In the second part, we demonstrated that the species U(AlH₄)₃ exists. This compound has been shown to catalyse the hydroalumination of olefins by LiAlH₄ with a very good anti-Markovnikov regioselectivity. We suggested a simple mecanism for this reaction. This was not possible with the d-block elements. The reactions of the organoaluminates products with several reactants (D₂0, I₂, CH₂O, Allyl-Br. . . ) has been shown to be a powerful synthetic tool. Few specific alkenes and alkynes exhibited an interesting behaviour as dimerization or β-alkyl elimination which are easily interpreted by our mecanism
Roger, Philippe. "Propriétés physicochimiques et catalytiques de mordenites modifiées par désalumination". Poitiers, 1989. http://www.theses.fr/1989POIT2308.
Pełny tekst źródłaTourneux, Lise. "Propriétés structurales et catalytiques des thymidine monophosphate kinases bactériennes". Paris 6, 1999. http://www.theses.fr/1999PA066499.
Pełny tekst źródłaNechadi-Boutarfa, Naïma. "Propriétés catalytiques en hydrogénation et propriétés adsorbantes des sulfures des métaux de transition". Lyon 1, 1987. http://www.theses.fr/1987LYO10532.
Pełny tekst źródłaMeloni, Daniela. "Propriétés acides et propriétés catalytiques d'une zéolithe à double système poreux : mcm-22". Poitiers, 2000. http://www.theses.fr/2000POIT2316.
Pełny tekst źródłaTomczak, Jan Martin. "Propriétés spectrales et optiques des Matériaux corrélés". Phd thesis, Ecole Polytechnique X, 2007. http://pastel.archives-ouvertes.fr/pastel-00003163.
Pełny tekst źródłaFricout, Gabriel. "Propriétés morphologiques et optiques des surfaces rugueuses". Phd thesis, École Nationale Supérieure des Mines de Paris, 2004. http://pastel.archives-ouvertes.fr/pastel-00001102.
Pełny tekst źródłaFricout, Gabriel Yrieix. "Propriétés morphologiques et optiques des surfaces rugueuses". Paris, ENMP, 2004. https://pastel.archives-ouvertes.fr/pastel-00001102.
Pełny tekst źródłaIn this PhD, we have focused our interest on studying general aspect of rough surfaces and particularly steel surfaces, that can be coated and designed for any kind of applications. In the following, the words surface aspect have to be understood as general texture characteristics without taking into account local defects. The control of such an aspect during production process is performed by regular sampling of the product and visual comparison with a reference data set. This method does not only forbid a continuous quality control of surface aspect, but also introduces a very subjective part in surfaces appearance evaluation. Firstly, we develop a set of morphological features (based on surface segmentation, tortuosity map, granulometry. . . ) as well as statistical features (covariance curve, slopes histogram. . . ), that leads us to surface characterization. The question of features stability is then considered by means of features variance when a large surface is characterized several times using independent observation windows. Some geostatistical tools enable us to address this problem in some particular cases and bootstrap over-sampling is also introduced with special care to statistical dependence between variables. A statistical method based on different steps of factorial analysis is then introduced in order to chose a representation space that is well suited for bayesian classification. This very generic methodology for analyzing surface texture is then applied to a real problem. We study the automatic classification of surfaces with "orangepeel" aspect according to the quality of their appearance. Once successful experiments were performed in laboratory using interferometric microscopy, we design a vision system based on a collimated source and a matricial camera, so that an automatic and systematic quality control of surface aspect can be set up on production line. In order to improve our classifier performance, the possibility of using flooding trees for texture characterization is considered and we develop an algorithm to divide a flooding tree into subtrees so that bootstrap techniques become usable with such a particular data structure. Finally, the optical behavior of surfaces is modeled by the way of ray casting in order to simulate the image obtained by a camera under specific lighting conditions. Reciprocally, we propose an algorithm to compute a surface topography if only a single camera image is known. All these points join a recent dynamic coming from steel industry in general and Arcelor group in particular, that should lead to a better understanding of esthetic for surfaces, the final aim being the prediction and anticipation of consumer’s desires in this particular field. Considering this, our tools open perspectives for defining the "ideal surface" for a given application
Leszczynski, Przemyslaw. "Propriétés optiques et magnéto-optiques de systèmes électroniques purement bidimensionnels graphène". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY002/document.
Pełny tekst źródłaDespite the massive attention that graphene has attracted in recent years, there are still many unanswered questions about its fundamental properties. In this work we present the results of a series of magneto-optical experiments performed on different graphene systems. The micro-Raman scattering spectroscopy was used as our method of choice, due to its non-invasive character, powerful characterization possibilities and high spatial resolution. The high magnetic fields were used to continuously tune the energy of inter-Landau level electronic excitations into a resonance with other excitations existing in the system. The magnetic field evolution of Raman active inter-Landau level excitations, and the details of the magneto-phonon resonance, gave us important information about the details of the electron-phonon interaction in graphene. Three different types of graphene are studied in this work. The first one consists of graphene flakes that can be found on the surface of graphite. It is possibly the least investigated graphene system, yet the one that shows the highest electronic quality. In Chapter 7 we present results of our magneto-Raman scattering experiments on this system. Our method for locating these flakes with the use of the magnetic field and without it is presented. The evolution of electronic excitations in magnetic fields is discussed. The effects of temperature, excitation wavelength and different coupling to the substrate are shown. We demonstrate that at high magnetic fields a fine-structure of the principal interband electronic excitation develops and discuss it in terms of doping and electron-hole asymmetry. A new type of a resonant electron-phonon interaction is observed, which involve an inter-valley carrier scattering and an emission of a K-point phonon. An analogous process for the phonons from the vicinity of the Γ point is observed.The second studied system consists of a graphene flake encapsulated between two layers of atomically flat hexagonal boron nitride (hBN). It is a representative of a novel class of materials, where different 2D crystals, are stacked on top of each other in a predefined order, to modify some properties of its constituents. Depositing graphene on a thin layer of hBN is expected to largely improve its electronic properties, as compared to graphene deposited on Si/SiO2. In Chapter 8 we present results obtained on such system. We show how spatial mapping with Raman scattering technique can be used for characterization and selective visualization of each constituent of the complex, stacked structures. A first, clear observation of a magneto-phonon resonance and L(-1,1) electronic excitation in an intrinsic, exfoliated graphene is shown. The Fermi velocity dependence on the magnetic field is demonstrated. Also, the Fermi velocity and 2D band energy dependence on the substrate is observed and discussed in terms of dielectric screening of the electron-electron interaction.The last studied system is the CVD grown graphene flake with electrical contacts. In Chapter 9 we show the results of an experiment, where strength of the electron-phonon interaction in a gated, CVD grown, graphene was successfully tuned by the applied gate voltage. We compare these results with the theoretical calculations and show that the intra-band electronic excitations play an important role in the renormalization of the phonon energy
Dubé, David. "Matériaux mésostructurés organosiliciques fonctionnalisés acides synthèse, caractérisation et propriétés catalytiques". Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26195/26195.pdf.
Pełny tekst źródłaFisette, Olivier. "Propriétés dynamiques et catalytiques des B-Lactamases de classe A". Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29651/29651.pdf.
Pełny tekst źródłaβ-Lactamases are the main bacterial mechanism of resistance against β-lactams. They inactivate these antibiotics by cleaving their β-lactam ring. Class A enzymes are the most prevalent, with a broad variety of substrate specificities. These proteins were studied by numerous experimental and theoretical studies. NMR spectroscopy measurements were performed in our laboratory on model enzymes TEM-1 and PSE-4. This project continues the investigation of the dynamic properties of these two β- lactamases using theoretical methods. An MD simulation protocol was established and validated using NMR relaxation data. A new joint MD/NMR analysis technique was developped, allowing a reduction of under- and over-fitting problems in model-free analysis. To compare class A β-lactamase dynamics in presence and absence of substrate, a potential was developped to describe β-lactams, taking into account the particular geometry and chemical potential of the β-lactam cycle. This force field is transferable, allowing the construction of a variety of antibiotics. Our simulations, along with past NMR studies, prove the existence of a dynamical duality in class A β-lactamases : they are highly structured on the ps-ns timescale, but also subjected to slow motions (µs-ms) in the vicinity of the active site, particularly in the Ω loop that borders the catalytic site. Ps-ns rigidity favors an optimal positioning of active site residues for an efficient catalysis, and allows the protein to tolerate potentially destabilizing mutations. The most interesting µs-ms motions are located in the Ω loop, confirming its regulatory role : it opens the active site for substrate entry and product release. Substrate binding has structuring long-range effects on TEM-1. Increased loop motions are also observed in both TEM-1 and PSE-4. However, specific interactions responsible for this higher flexibility vary between the two enzymes : protein dynamics properties are conserved.
Tableau d'honneur de la FÉSP
MONTES, RENDON ARTURO. "Préparation et propriétés catalytiques de métaux de transition sur mordenité". Poitiers, 1987. http://www.theses.fr/1987POIT2037.
Pełny tekst źródłaFisette, Olivier. "Propriétés dynamiques et catalytiques des β-Lactamases de classe A". Doctoral thesis, Université Laval, 2012. http://hdl.handle.net/20.500.11794/23975.
Pełny tekst źródłaLes β-lactamases sont le principal mécanisme bactérien de défense contre les β-lactamines. Elles catalysent l’inactivation de ces antibiotique par le clivage de leur noyau β-lactame. Les β-lactamases les plus communes sont celles de la classe A, qui rassemble une grande variété d’enzymes aux spécificités de substrat variées. Ces protéines ont été l’objet de nombreuses recherches expérimentales et théoriques. Plusieurs études de dynamique par spectroscopie RMN ont été réalisées dans notre laboratoire sur les enzymes modèles TEM-1 et PSE-4. Le présent projet continue l’investigation de ces deux β-lactamases par des méthodes théoriques. Un protocole de simulation de DM a été établi et validé par comparaison avec des données de relaxation RMN. Une nouvelle technique d’analyse conjointe DM/RMN a également été développée, permettant de limiter les problèmes de sous et sur-ajustement présents dans l’analyse « model-free ». Pour comparer la dynamique des β-lactamases de classe A en présence et en absence de leur substrat, un potentiel pour les β-lactamines a été développé, en tenant compte de la géométrie et du potentiel chimique particuliers du noyau β-lactame. Ce champ de forces est transférable, permettant la construction d’une variété d’antibiotiques. Nos simulations, couplées aux précédentes études par RMN, démontrent qu’il existe une dualité dynamique dans les β-lactamases de classe A : elles sont hautement structurées à l’échelle ps-ns, mais aussi le siège de mouvements lents (µs-ms) aux abords du site actif et particulièrement dans la boucle qui borde le site catalytique. La rigidité ps-ns favorise un positionnement optimal des résidus du site actif pour une catalyse efficace, et permet la tolérance de mutations potentiellement déstabilisantes. Les mouvements à l’échelle µs-ms les plus intéressants sont localisés dans la boucle Ω et confirment son rôle régulatoire : elle permet l’ouverture du site actif pour l’entrée du substrat et le largage du produit. La liaison du substrat a des effets à longue portée rigidifiant TEM-1. On observe également un mouvement accru de la boucle Ω dans TEM-1 et PSE-4. Les interactions spécifiques menant à cette plus grande flexibilité varient toutefois d’une enzyme à l’autre : il y conservation des propriétés dynamiques.
β-Lactamases are the main bacterial mechanism of resistance against β-lactams. They inactivate these antibiotics by cleaving their β-lactam ring. Class A enzymes are the most prevalent, with a broad variety of substrate specificities. These proteins were studied by numerous experimental and theoretical studies. NMR spectroscopy measurements were performed in our laboratory on model enzymes TEM-1 and PSE-4. This project continues the investigation of the dynamic properties of these two β- lactamases using theoretical methods. An MD simulation protocol was established and validated using NMR relaxation data. A new joint MD/NMR analysis technique was developped, allowing a reduction of under- and over-fitting problems in model-free analysis. To compare class A β-lactamase dynamics in presence and absence of substrate, a potential was developped to describe β-lactams, taking into account the particular geometry and chemical potential of the β-lactam cycle. This force field is transferable, allowing the construction of a variety of antibiotics. Our simulations, along with past NMR studies, prove the existence of a dynamical duality in class A β-lactamases : they are highly structured on the ps-ns timescale, but also subjected to slow motions (µs-ms) in the vicinity of the active site, particularly in the Ω loop that borders the catalytic site. Ps-ns rigidity favors an optimal positioning of active site residues for an efficient catalysis, and allows the protein to tolerate potentially destabilizing mutations. The most interesting µs-ms motions are located in the Ω loop, confirming its regulatory role : it opens the active site for substrate entry and product release. Substrate binding has structuring long-range effects on TEM-1. Increased loop motions are also observed in both TEM-1 and PSE-4. However, specific interactions responsible for this higher flexibility vary between the two enzymes : protein dynamics properties are conserved.
Abou, Hamdan Abbas. "Etude pluridisciplinaire d'une hydrogénase : mécanisme et optimisation des propriétés catalytiques". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4752.
Pełny tekst źródłaHydrogenases are metalloenzymes which catalyse the reversible conversion of dihydrogen into protons and electrons. In my work, I focused on some aspects of the catalytic mechanism of the heterodimeric NiFe hydrogenase from Desulfovibrio fructosovorans. We demonstrated that, contrary to the commonly accepted mechanism of aerobic inactivation, the attacking O2 is not incorporated as an active site ligand but rather acts as an electron acceptor. This finding calls for a re-examination of the mechanism for O2 tolerance of the natural O2 tolerant NiFe hydrogenases. We also described a simple analytical model that we used to analyse the complex voltammetric signals of 16 mutants obtained by substituting an amino acid near the active site. We demonstrated that this substitution can accelerate anaerobic inactivation and reactivation by up to three orders of magnitude. We also demonstrated and explained the correlation between these rates and O2-tolerance. We studied mutants whose H2-production activity is impaired. We found that the rate limiting step of this reaction is the diffusion of hydrogen out of the enzyme, through the hydrophobic channel. Finally, we focused on a threonine belonging to the putative proton transfer pathway. We demonstrated that this amino acid is indeed implicated in proton transport. It may also play a crucial role in the stabilization of intermediates formed during the catalytic cycle, and probably also in determining the rate of electron transfer and diffusion along the gas channel
Galletti, Daniel. "Propriétés catalytiques et désactivation de particules submicroniques de nickel et de palladium". Toulouse 3, 1990. http://www.theses.fr/1990TOU30007.
Pełny tekst źródłaRoyer, Pascal. "Etude théorique et expérimentale des propriétés optiques de particules submicroniques d'argent". Dijon, 1987. http://www.theses.fr/1987DIJOS019.
Pełny tekst źródłaLamouche, Guy. "Propriétés optiques des semiconducteurs, impuretés et points quantiques". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21480.pdf.
Pełny tekst źródłaBayle, Maxime. "Architectures plasmoniques enterrées : élaboration, propriétés optiques et applications". Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2664/.
Pełny tekst źródłaIn our work, we present the study of plasmonic architectures made of a plane of nanoparticules (NPs) embedded at the vicinity of a dielectric matrix free surface, by low energy ion beam synthesis. Materials structural analysis, especially by transmission electron microscopy, have been carried out to determine the impact of the elaboration process parameters on the three dimensional organization of the NPs, in silicon dioxide or nitride layers grown on silicon substrates. To systematically check these parameters, we studied the elastic and inelastic optical responses of the heterostructures. The elastic response has been obtained by measuring the reflectance of the samples, and confronted to numerical modelling we developed, to determine the mean size of the NPs and the implanted silver amount. The study of the electric field topography allowed us to take benefit from both plasmonic resonance and optical amplification in antireflective layers. The inelastic response has been studied using Raman spectroscopy over a wide frequency range: vibrational collective modes (Lamb modes) of the NPs have been studied at low frequency, while at higher frequency, we have extracted the vibrational density of states (VDOS). Combined with atomistic simulations, the VDOS gave us original information on the vibrational dynamics and the thermodynamic properties of buried silver NPs (and deposited gold NPs). Finally, we present some applications of the assemblies of NPs in hybrid devices, such as the use of coupling between these NPs and deposited substances (e. G. Graphene) on our substrates. In particular, it can be used for surface enhanced Raman spectroscopy (SERS). Then using techniques from microelectronics, we designed plasmo-electronic devices exploiting photoconductance properties of these buried or deposited NPs assemblies
Fontcuberta, i. Morral Anna. "Croissance, propriétés structurales et optiques du silicium polymorphe". Palaiseau, Ecole polytechnique, 2001. http://www.theses.fr/2001EPXX0033.
Pełny tekst źródłaQuach, Alida. "Films mésoporeux hybrides : propriétés optiques et applications potentielles". Paris 6, 2007. http://www.theses.fr/2007PA066649.
Pełny tekst źródłaMenard, Stéphane. "Propriétés optiques et électriques des nanostructures Si/CaF2". Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10235.
Pełny tekst źródłaDuboz, Jean-Yves. "Propriétés électroniques et optiques des hétérostructures métal/semiconducteur". Grenoble 1, 1990. http://www.theses.fr/1990GRE10027.
Pełny tekst źródłaPeres, Laurent. "Synthèse et propriétés catalytiques de nanoparticules de platine de formes contrôlées". Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0002.
Pełny tekst źródłaSolution chemistry allows obtaining nanoparticles with well-controlled structural characteristics. It offers therefore the possibility to exploit the specific properties associated to the nano-objects characteristics (size, shape, crystal phase …), in diverse applications. Among them, catalysis plays an important role for the ecologic/energetic transition. Indeed, for numerous reactions, the use of nanoparticles allows to reduce the amount of metals employed. Moreover, some metals present new properties at this scale. As a surface phenomenon, catalysis thus implies more and more the use of size and shape controlled nanocrystals. Indeed, literature has shown that it is possible to modulate catalyst activity and selectivity depending on the crystallographic orientation of the nanocrystal facets.In the first part of this thesis, platinum nanoparticles have been produced using a simple Pt(II) salt as a principal precursor. Depending on the parameters employed, various shapes have been obtained. We have tried to understand the formation mechanism of the different platinum nanoparticle morphologies obtained: concave cubes enclosed by (110) facets, multipods enclosed by a mix of (111) and (100) and cubes enclosed by (100) facets. The second chapter aims at studying the impact of the nano-object shape in a model catalytic reaction. Concaves cubes and multipods have been tested in the hydrogenation of an α,β-unsaturated aldehyde, the cinnamaldéhyde, as a model reaction to probe chemoselectivity. Free nanoparticles in solution and nanoparticles supported on silica and graphène have been used. Finally, the extension of a method for the epitaxial growth of nanocrystals on thin films, allowed the elaboration of, crystallographically oriented, shape controlled platinum nano-objects (concave cubes, wires) by a direct solution-growth, over different thin films of specific nature and crystalline orientation
Bourgeat-Lami, Elodie. "Etude des propriétés physico-chimiques et catalytiques de la zéolithe bêta". Montpellier 2, 1991. http://www.theses.fr/1991MON20181.
Pełny tekst źródłaMbomekalle, Israël Martyr. "Synthèse, caractérisation, électrochimie et études des propriétés catalytiques de nouveaux hétéropolyanions". Paris 11, 2003. http://www.theses.fr/2003PA112247.
Pełny tekst źródłaThis work is devoted to the synthesis, characterization and electrochemistry of new dissymmetrical Dawson type heteropolyanions with the general formula [H4XW18O62]^7- (X = P or As) and their substituted derivatives. All these new compounds were characterized by various methods of physicochemical analysis (elemental analysis, IR, 31P and 183W NMR, cyclic voltammetry) which showed that pure isomer samples were obtained. Detailed electrochemical studies on the behaviour of monosubstituted species, the behaviour of the electroactive metal centres like CUII or the transfer of electrons between FeIII centres within the same sandwich Dawson molecule were carried out. X-ray diffraction on monocrystals allowed the determination of new structures, such as the "BANANA" type structure, or of not yet solved structures, of several Dawson Sandwich compounds. Magnetization studies were undertaken on these compounds which comprise several metal centres. Studied compounds proved very efficient in the catalysis of the reduction of nitrogen oxides, dioxygen or hydrogen peroxide, the catalysis of the coenzyme NADPH oxidation and the oxidation of olefin hydrocarbons. This work is part of the development program of new structures, or even of new properties in the chemistry and the electrochemistry of heteropolyanions. The prospects remain enormous and diversified
Ajroudi, LIlia. "Ferrites de cobalt nanostructurés ; élaboration, caractérisation, propriétés catalytiques, électriques et magnétiques". Thesis, Toulon, 2011. http://www.theses.fr/2011TOUL0017/document.
Pełny tekst źródłaThis work is devoted to the synthesis and the study of the physical properties of cobalt ferrite nanomaterials. Thecobalt ferrite nanopowders (CoxFe3-xO4 , x=0.6,1,1.2,1.8 ) were synthesized by a new solvo thermal chemical route.The nanopowders are highly crystallized, very homogeneous in size and chemical composition. The nanopowderssizes are ranged from 4 nm for high cobalt content to 7 nm for low cobalt content. They are single phased, with thespinel structure, and a cell parameter varying with the cobalt content. The cobalt ferrites do not oxidize, when heatedunder air. For compositions near x=1, the cobalt ferrites are stable when heated under air up to 900°C, as for the othercompositions, phase transformations occur above 550°C.The catalytic measurements have shown the oxidation of CH4 into CO2 in presence of the catalyst for all thecompositions. Cobalt ferrite with composition x=1.8, presents the lowest activation energy and the best catalyticefficiency; this can be related to the great specific surface and the high rate of active sites for this composition.Concerning the conduction properties, the cobalt ferrites exhibit a semiconductor character up to 500-600 ° C and ametallic one above. Changes in conductivity from a composition to another are explained by changes in the number ofpairs [Co2+, Fe3+].A superparamagnetic behaviour was evidenced whatever the composition. This is due for one part to a size and shapeeffect and for the other part to different cationic distribution between tetrahedral and octahedral sites. These ferriteshave a saturation magnetization close to that of the massive state, because of the high crystallinity of the nanopowders,attributed to the synthesis method developed in this work
Demange, Valérie. "Seléction, élaboration et caractérisation d'alliages et de couches minces approximants Al-Cr-Fe". Vandoeuvre-les-Nancy, INPL, 2001. http://www.theses.fr/2001INPL568N.
Pełny tekst źródłaVitucci, Francesco Maria. "Propriétés optiques et magnétiques de matériaux multiferroïques : gaFeO3 et LuFe2O4". Thesis, Tours, 2010. http://www.theses.fr/2010TOUR4017/document.
Pełny tekst źródłaWe present a contribution to the study of structural, electronic and magnetic propertiesof multiferroic compounds. These materials – characterized by the coexistence and coupling of different types of long-range orders, such as magnetic and ferroelectic – have recently become a subject of great importance because of their academic interest and their significance for potential applications. In this context we have studied the two compounds GaFeO₃ and LuFe₂O₄. The study involved the use of several techniques : electronic spin resonance (ESR), magnetic measurements by magnetometry and infrared spectroscopy (IR).Local and macroscopic magnetic measurements reveal an anomalous paramagnetic phase in GaFeO3. This is attributed to the existence of short-range magnetic correlations in a wide temperature range above the ordering temperature. On the other hand, the analysis of IR phonon spectra recorded at different temperatures (10 ≤ T ≤ 1000 K) shows that the ordering of magnetic moments does not affect the structural properties of GaFeO₃ For LuFe₂O₄, conversely, the magnetic degrees of freedom are coupled to the structural properties via the charge ordering of Fe³+/Fe²+ ions, as suggested by ESR and IR spectroscopy
Vallayer, Julien. "Corrélations entre les propriétés optiques, diélectriques et mécaniques de l'alumine". Ecully, Ecole centrale de Lyon, 1999. http://www.theses.fr/1999ECDL0041.
Pełny tekst źródłaBaida, Hatim. "Propriétés optiques et spectroscopie non-linéaire de nanoparticules individuelles". Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00713129.
Pełny tekst źródłaRicard, Vincent. "Aérosols dans l'Arctique européen : sources, transformations et propriétés optiques". Phd thesis, Université Joseph Fourier (Grenoble), 2001. http://tel.archives-ouvertes.fr/tel-00701298.
Pełny tekst źródłaSolanki, Amit. "Propriétés électriques et optiques des nanofils uniques de silicium". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00846580.
Pełny tekst źródłaBachelier, Guillaume. "Propriétés optiques de nano-structures métalliques et semi-conductrices". Phd thesis, Université Paul Sabatier - Toulouse III, 2004. http://tel.archives-ouvertes.fr/tel-00008229.
Pełny tekst źródłaLecarme, Olivier. "Propriétés optiques de colloïdes assemblés : plasmonique et confinement diélectrique". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00680026.
Pełny tekst źródłaJi, Botao. "Synthèse et propriétés optiques de quantum dots fluorescents plasmoniques". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://pastel.archives-ouvertes.fr/pastel-01065068.
Pełny tekst źródłaArnaud, Gérald. "Structure électronique et propriétés optiques des hétérostructures InGaAs-GaAs". Montpellier 2, 1991. http://www.theses.fr/1991MON20242.
Pełny tekst źródłaUlmer, Tuffigo Hélène. "Propriétés optiques des puits quantiques et superréseaux CdTe/CdZnTe". Grenoble 1, 1990. http://www.theses.fr/1990GRE10052.
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