Oxygen diffusion through the disordered oxide network during silicon oxidation

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The aim in this project was the optimization of LaFeO3-based perovskite materials for oxygen separation membranes (OSM). The work was carried out by the Laboratory for High Performance Ceramics, Empa in collaboration with the Laboratory for Industrial Energy Systems, LENI, EPFL and the Ceramics Laboratory, LC, EPFL. The ceramic material of interest is a mixed conductor for oxygen ions and electrons at high temperature (800°-900°C) and therefore can separate oxygen from nitrogen with 100% selectivity when

A pulsed field gradient NMR (= nuclear magnetic resonance) method using stimulated echoes for determining the translational isotropic or anisotropic diffusion coefficient of a molecule or supramolecular assembly or the flow rate and direction of fluids containing such molecules is characterized in that the molecule or supramolecular assembly contains one or several isotopes (X) of non-zero nuclear spin other than protons having longitudinal relaxation times T1(X) that are longer than the longitudinal relaxa

The oxidn. of nickel gauze catalysts by O2 was investigated by transient response methods. Qual. description of the exptl. transient responses have shown that the oxidn. of metallic nickel proceeds in two stages. The first step is a fast dissocn. of gaseous oxygen on the catalytic surface, followed by oxygen diffusion from the surface into the bulk. This slow second step explains the long tailing obsd. from the exptl. transient responses. Furthermore, a rise of temp. was obsd. during the nickel oxidn. A kin

Three perovskite-type compounds of composition La0.4Ca0.6Fe1-xCoxO3-d (x=o, o.25 and 0.5) were investigated for use as oxygen separation membranes for the partial oxidation (POX) of methane to syngas. Special attention was given to the question of their stability in real operating conditions. A permeation set-up was specially designed to measure oxygen fluxes through these materials when placed in a strong pO2 gradient. It also facilitated testing the long-term stability of the specimen. Permeation measurem

We modeled liquid oxygen using ab initio molecular dynamics in which both the atomic structure and the noncollinear magnetic structure evolve without constraints. The atomic structure shows preference for parallel alignment of first-neighbor molecules and is supported by an excellent agreement between theoretical and experimental nuclear structure factors. The magnetic structure shows short-range antiferromagnetic correlations in agreement with spin-polarized neutron diffraction data. The observed correlati

We consider the problem of routing in a wide area mobile ad-hoc network called Terminode Network. Routing in this network is designed with the following objectives. First, it should scale well in terms of the number of nodes and geographical coverage

We propose a novel approach to Quality of Service, intended for IP over SONET (or IP over WDM) networks, that offers end-users the choice between two service classes defined according to their level of transmission protection. The first service class (called Fully Protected (FP)) offers end-users a guarantee of survivability: all FP traffic is protected in the case of a (single) failure. The second service class (called Best-Effort Protected (BEP)) does not offer any specific level of protection but is chea

The gas phase species produced in rf plasmas of hexamethyldisiloxane (HMDSO), Si2O(CH3)(6), diluted with oxygen, have been investigated. The complementarity of Fourier transform infrared absorption spectroscopy and mass spectrometry allows the determination of the most abundant neutral components present in the discharge. The measurements reveal that methyl groups (CH3), abundantly formed by the dissociation of the HMDSO molecule, are the precursor for the most abundant species which stem from two kinds of

The Laboratory of Electrical Machines of the Swiss Federal Institute of Technology (Lausanne) has developed a software (TLSim) for the simulation of electrical urban transportation systems. This program can simulate the behaviour of the power supply network (current and voltage level at any point of the topology) comprising uni- and bi- directionnal sub-stations. In the network the vehicules (trolleybus) may run along any defined path through different electrical supply sectors. Several models of trolleybus

The numerical modeling of solutes absorption processes by the arterial wall is of paramount interest for the understanding of the relationships between the local features of blood flow, the nourishing of the inner arterial wall by the blood solutes, and the pathologies that can appear when this process is for some reason perturbed. In the present work, two models for the solutes dynamics are investigated. In the first model, which is essentially based on the one introduced by Rappitsch and Perktold (1996) a

According to Khan et al. [Khan, A. U., Kovacic, D., Kolbanovskiy, A., Desai, M., Frenkel, K. & Geacintov, N. E. (2000) Proc. Natl. Acad. Sci. USA 97, 2984-2989], peroxynitrite (ONOO(-)) decomposes after protonation to singlet oxygen ((1)Delta(g)O(2)) and singlet oxonitrate (nitroxyl, (1)NO(-)) in high yield. They claimed to have observed nitrosyl hemoglobin from the reaction of NO(-) with methemoglobin; however, contamination with hydrogen peroxide gave rise to ferryl hemoglobin, the spectrum of which was m

A simple and efficient technique for the fabrication of buried microfluidic channels is presented. Microchannels made using a contribution of thick liquid and laminated photopolymers are used for the realization of smart microchips for culture, stimulation and recording of neural cell arrays. (C) 1998 Elsevier Science S.A. All rights reserved.

Oxygen diffusion through the disordered oxide network during silicon oxidation

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Optimization of mixed conducting perovskites for the application in dense ceramic oxygen separation membranes, used in partial oxidation of natural gas to synthesis gas

SLOW DIFFUSION AND FLOW OF MOLECULES MEASURED BY PULSED FIELD GRADIENT NMR USING LONGITUDINAL MAGNETISATION OF NON-PROTON ISOTOPES

Mathematical modelling of the unsteady-state oxidation of nickel gauze catalysts

Oxygen permeation and stability of La0.4Ca0.6Fe1 - xCoxO3-delta (x=0, 0.25, 0.5) membranes

Ab initio molecular dynamics investigation of the structure and the noncollinear magnetism in liquid oxygen: Occurrence of O-4 molecular units

Self Organized Terminode Routing

A Protection-based Approach to QoS in Packet over Fiber Networks

Oxygen diluted hexamethyldisiloxane plasmas investigated by means of in situ infrared absorption spectroscopy and mass spectrometry

TLSim: A software for Electrical Public Transportation Systems

Mathematical and numerical modeling of solute dynamics in blood flow and arterial walls

Peroxynitrite does not decompose to singlet oxygen ((1)Delta (g)O(2)) and nitroxyl (NO(-))

Buried microchannels in photopolymer for delivering of solutions to neurons in a network