Search results for "oxydation"
showing 10 items of 32 documents
Etude comparative du catabolisme de l'acide ricinoléique chez les levures du genre Sporidiobolus : mise en évidence et caractérisation du système bét…
2002
*INRA Centre de Dijon (FRA) Diffusion du document : INRA Centre de Dijon (FRA) Diplôme : Dr. d'Université
Synthesis and Characterization of TiO2 Based Inorganic-Organic Hybrid Photocatalysts for Enhancing the Selective Formation of 4-Methoxy-benzaldehyde …
2015
The oxidation of alcohols to carbonyl compounds in a clean fashion (i.e., with water as a solvent or under solvent-free conditions, and using O2 or H2O2 as the primary oxidant) is the subject of considerable research efforts. A new approach for the selective oxidation of soluble aromatic alcohols in water under mild conditions via a novel composite photocatalyst has been developed. The catalyst is synthesized by grafting 4-(4-(4- hydroxyphenylimino)cyclohexa-2,5dienylideneamino)phenol and silver nanoparticles onto the surface of moderately crystalline titanium dioxide. The titanium dioxide-based composite was first extensively characterized and then employed in the catalytic oxidation of 4-…
Adsorption and diffusion study, in gazeous phase, of wine active molecules in cork
2010
During wine ageing, oxidation reactions occur and can lead to wine sensory defaults. The main factors involved in this phenomenon are oxygen and gas barrier properties of stoppers. During the last ten years, some studies investigated oxygen transfer during winemaking and wine storage. However, only few of them deal with the interactions between molecules and sealing materials. The material studied in this work is raw cork, without any treatment, neither washed nor surface treated (with paraffin or silicone). This Phd work focuses on mass transfer of some wine active molecules, in gas phase, through the cork. The selected molecules are water, ethanol, sulphur dioxide and oxygen. An adsorptio…
Modélisation de phénomènes locaux : vers leur prise en compte dans la simulation de la cinétique d'oxydation d'un métal.
2006
The oxidation of metals is a complex process involving several mechanisms that take place at different length scale (macroscopic and microscopic). In this work, we try to integrate local phenomena (microscopic scale) in macroscopic models, especially to the modelling of the metal oxidation kinetics. The study is divided in two parts ; the first one based on non-equilibrium thermodynamics allows us to obtain the evolution laws of the system metal/oxyde, those were used to modelling oxidation kinetics. The second one is microscopic ; it consists in a study of the thermo-mechanical behaviour of various aluminium surfaces by molecular dynamic and the calculation of their surface energy density.…
Contribution to the molecular study of the oxidative stability of white wines of Burgundy
2019
In order to understand and control the aging of wines, particularly white wines, it is necessary to deepen our knowledge about the physico-chemical mechanisms of oxidation related to oxygenation processes. For this, it is important to have tools to quantify the antioxidant capacity of white wines, and to identify the compoiunds involved, in order to anticipate the aging ability of a wine.In this study, analyzes of the antioxidant capacity by DPPH and Electron Paramagnetic Resonance (EPR) were carried out on a large number of wines during aging and from several vintages, in parallel with metabolomic analyzes, mainly carried out by Liquid Chromatography Coupled to Mass Spectrometry (UPLC-Q-TO…
Functionalised Imidazoporphyrins and their application in catalysis
2017
A broad series of functionalized imidazo[4,5-b]porphyrins was synthesized by the acid-catalyzed condensation of 2,3-dioxo-5,10,15,20-tetraarylchlorins with aromatic aldehydes. Both steric and electronic features of meso-aryl substituents influence on the product yield ranging from 18% to 90%.Single-crystal X-ray diffraction analysis of the structure of zinc(II) 5,10,15,20-tetramesityl-2-(4-pyridyl)-1H-imidazo[4,5-b]porphyrinate showed that this compound forms 1D coordination chains in the solid state.The post-synthetic modifications of imidazo[4,5-b]porphyrins were investigated by performing the Suzuki-Miyaura coupling reaction, preparing water-soluble imidazoporphyrins and linear/angular b…
Efficacity of SMAT and laser shock-peening process for enhancement of titanium alloys high temperature oxidation resistance
2017
The aim of this thesis is to determine the influence of two mechanical surface treatments, the shot- peening performed with several type of balls (WC, alumina and glass) and the laser shock peening, on the high temperature oxidation resistance of two titanium alloys : alpha alloy with commercially purity (Grade 1) and aeronautical beta metastable alloy (TIMETAL-21S).After different treatments, the pieces are oxidized with different conditions: of time (between 5 hours to study the firsts times of oxidation and 3000 hours to compare with a classical aeronautical test), of temperature (600°C to 700°C) and atmosphere (dry air or oxygen).The pieces are analyzed before and after oxidation exposu…
Conservation and functional preservation of agri-food interest yeasts
2018
The use of yeasts in industry is inseparable from their ability to be produced and dehydrated. This dehydration process causes various dysfunctions in yeast cells that affect their functionality and viability. In order to protect yeasts from dehydration, food additives are often used as emulsifiers and antioxidants. However, yeasts are able to produce naturally protective substances, such as glutathione (GSH) and trehalose (TRE). In this context, three non-Saccharomyces (NS) strains, belonging to the different genera and species Torulaspora delbrueckii, Metschnikowia pulcherrima and Lachancea thermotolerans, were studied in this thesis. Despite the great interest aroused by their multiple a…
Study of a chromia-forming alloy behavior as interconnect material for High Temperature Vapor Electrolysis
2011
In High Temperature Vapor Electrolysis (HTVE) system, the materials chosen for the interconnectors should have a good corrosion behaviour in air and in H2-H2O mixtures at 800°C, and keep a high electronic conductivity over long durations as well. In this context, the first goal of this study was to evaluate a commercial ferritic alloy (the K41X alloy) as interconnect for HTVE application. Oxidation tests in furnace and in microbalance have therefore been carried out in order to determine oxidation kinetics. Meanwhile, the Area Specific Resistance (ASR) was evaluated by Contact Resistance measurements performed at 800°C. The second objective was to improve our comprehension of chromia-formin…
Additive manufacturing, new elaboration technique of metallic materials : impact of the microstructure on high temperature durability of AISI 316L st…
2021
Additive Manufacturing (AM) processes are able to elaborate, in a single step, metallic parts with very complex geometry, as close as possible to their final dimensions, based on 3D CAD model. Despite a very large number of studies on AM parameters, very few studies report on the high temperature behavior of the metallic materials produced by these processes. This thesis work evaluates the impact of the Selective Laser Melting (SLM) process on the high temperature durability of the austenitic stainless steel AISI 316L, commercial grade widely used in the industry. For this purpose, the reactivity of SLM samples was studied in different conditions (atmosphere, temperature, isothermal or cycl…