Génie chimique | EPFL Graph Search

Le génie chimique, ou génie des procédés physico-chimiques, désigne l'application de la chimie physique à l'échelle industrielle. Elle a pour but la transformation de la matière dans un cadre industriel et consiste en la conception, le dimensionnement et le fonctionnement d'un procédé comportant une ou plusieurs transformations chimiques et/ou physiques. Les méthodes utilisées dans un laboratoire ne sont souvent pas adaptées à la production industrielle d'un point de vue économique et technique. Le génie chimique permet ainsi le passage d'une synthèse de laboratoire à un procédé industriel de même que son fonctionnement dans le respect des contraintes économiques, techniques, environnementales et de sécurité. Le génie chimique se situe à la convergence de plusieurs disciplines et étudie les transformations, les transports et les transferts de la matière, de l'énergie et de la quantité de mouvement pour établir des lois et des corrélations utilisables lors de la transposition ou de l'

The Chemistry of Neurodegeneration: Kinetic Data and Their Implications

Matej Repic

We collected experimental kinetic rate constants for chemical processes responsible for the development and progress of neurodegeneration, focused on the enzymatic and non-enzymatic degradation of amine neurotransmitters and their reactive and neurotoxic metabolites. A gross scheme of neurodegeneration on the molecular level is based on two pathways. Firstly, reactive species oxidise heavy atom ions, which enhances the interaction with alpha-synuclein, thus promoting its folding to the beta form and giving rise to insoluble amyloid plaques. The latter prevents the function of vesicular transport leading to gradual neuronal death. In the second pathway, radical species, OH center dot in particular, react with the methylene groups of the apolar part of the lipid bilayer of either the cell or mitochondrial wall, resulting in membrane leakage followed by dyshomeostasis, loss of resting potential and neuron death. Unlike all other central neural system (CNS)-relevant biogenic amines, dopamine and noradrenaline are capable of a non-enzymatic auto-oxidative reaction, which produces hydrogen peroxide. This reaction is not limited to the mitochondrial membrane where scavenging enzymes, such as catalase, are located. On the other hand, dopamine and its metabolites, such as dopamine-o-quinone, dopaminechrome, 5,6-dihydroxyindole and indo-5,6-quinone, also interact directly with alpha-synuclein and reversibly inhibit plaque formation. We consider the role of the heavy metal ions, selected scavengers and scavenging enzymes, and discuss the relevance of certain foods and food supplements, including curcumin, garlic, N-acetyl cysteine, caffeine and red wine, as well as the long-term administration of non-steroid anti-inflammatory drugs and occasional tobacco smoking, that could all act toward preventing neurodegeneration. The current analysis can be employed in developing strategies for the prevention and treatment of neurodegeneration, and, hopefully, aid in the building of an overall kinetic molecular model of neurodegeneration itself.

Humana Press Inc2016

Analysis of Fluid-Fluid Reaction Systems with Reactions in Both Phases

Adrien Calabria

Developing mathematical models for chemical reaction systems is essential for analysis, development, design, optimization and control of chemical, or biochemical industrial processes. Nowadays, more and more companies across the world have to deal with innovative concepts such as the Sustainable Chemistry (or "Green Chemistry"), which particularly require good knowledge of chemical reactions systems. Well-defined chemical operations involved in a process lead to its efficiency, energy saving and an improvement of the product quality. Furthermore, plants adopting this new philosophy minimize their byproduct production and pollutant formation. This master thesis works on developing a methodology for analysis and kinetic modeling of chemical reaction systems. In this present study, the case where chemical reactions take place in both phases of a heterogeneous biphasic fluid-fluid (F-F) reactor under isothermal conditions is considered. In order to model homogeneous or heterogeneous (F-F) chemical systems, a new approach called “Extent-based Incremental Identification” has recently been developed by the Laboratoire d’Automatique (EPFL). In contrast to the commonly used simultaneous approach, this extent-based incremental approach can compute parameters corresponding to reaction and mass transfer rates individually for each reaction and mass transfer laws, and also does not require prior postulation or knowledge of rate laws. This particular case is an extension of the dissertation done by Nirav Bhatt [1], which considers a heterogeneous chemical reaction system with reactions in one of the phases with steady state mass-transfer between the phases, and work done by Michael Amrhein [2], who developed a linear transformation that computed the extents of reaction from the numbers of moles in homogeneous reaction systems, with inlet and outlet streams. [1] Nirav Bhatt, EPFL Diss. n° 5028 (2011) [2] Amrhein et al., AIChE J. 56 (2010), 2873-2886

2013

Solid freeform fabrication of porous ceramic parts from ceramic powders and preceramic polymers

Thomas Alexandre

This dissertation addresses the development of a Solid Freeform Fabrication process, Selective Laser Pyrolysis, to fabricate three-dimensional porous ceramic preforms from ceramic powders and preceramic polymers. It contributes to a better understanding of the physical and chemical phenomena that intervene in this process. During this study, modeling tools were adapted and characterization techniques for porous parts were developed. The first part of this work describes the fabrication of porous preforms by using Selective Laser Pyrolysis. The choice of the fabrication process is discussed, as well as the choice of the materials used. The selected materials are characterized and methods to associate them are investigated. Finally, the microstructures of the resulting porous preforms are characterized. The second part of this study is devoted to the fundamental understanding of the various phenomena occurring during the fabrication process. These phenomena are characterized or modeled. The laser-matter interaction is investigated, and a thermal model adapted to the system is proposed. This model takes into account the laser-matter interaction, the non-linear heat diffusion process and the varying properties of the materials during the process. Results of simulations are compared with experimental data that empirically validate this model. Standard characterization techniques of mechanical properties are not adapted to porous preforms fabricated in this work. Therefore, an indentation technique is developed to evaluate the effect of process parameters on the mechanical behavior. Results of simulations with the thermal model and indentation tests are used to optimize the fabrication process.

EPFL2007