Search results for "Mite"
showing 10 items of 795 documents
Brief Review of the Effects of Pressure on Wolframite-Type Oxides
2018
In this article we review the advances that have been made on the understanding of the high-pressure structural, vibrational, and electronic properties of wolframite-type oxides since the first works in the early 1990s. Mainly tungstates, which are the best known wolframites, but also tantalates and niobates, with an isomorphic ambient-pressure wolframite structure, have been included in this review. Apart from estimating the bulk moduli of all known wolframites; the cation-oxygen bond distances and their change with pressure have been correlated with their compressibility. The composition variations of all wolframites have been employed to understand their different structural phase transi…
A Brief Review of the Effects of Pressure on Wolframite-Type Oxides
2018
In this article, we review the advances that have been made on the understanding of the high-pressure (HP) structural, vibrational, and electronic properties of wolframite-type oxides since the first works in the early 1990s. Mainly tungstates, which are the best known wolframites, but also tantalates and niobates, with an isomorphic ambient-pressure wolframite structure, have been included in this review. Apart from estimating the bulk moduli of all known wolframites, the cation–oxygen bond distances and their change with pressure have been correlated with their compressibility. The composition variations of all wolframites have been employed to understand their different structural phase …
Local atomic and electronic structure of tungsten ions in AWO4 crystals of scheelite and wolframite types
2001
Abstract X-ray absorption spectroscopy was used to study the local atomic and electronic structure of tungsten ions in polycrystalline scheelite CaWO4 and wolframite-type ZnWO4 and NiWO4. The W L1- and L3-edges X-ray absorption near edge structure (XANES) signals suggest tetrahedral coordination of tungsten ions in CaWO4 and strongly distorted octahedral coordination in ZnWO4 and NiWO4. Accurate analysis of the W L3-edge extended X-ray absorption fine structure (EXAFS) signals by the regularization procedure was performed to reconstruct the radial distribution functions within the first coordination shell around tungsten atoms in AWO4 crystals and polycrystalline WO3, which was utilized for…
Optimization of the first wall for the DEMO water cooled lithium lead blanket
2015
The maximum heat load capacity of a DEMO First Wall (FW) of reasonable cost may impact the decision of the implementation of limiters in DEMO. An estimate of the engineering limit of the FW heat load capacity is an essential input for this decision. This paper describes the work performed to optimize the FW of the Water Cooled Lithium-Lead (WCLL) blanket concept for DEMO fusion reactor in order to increase its maximum heat load capacity. The optimization is based on the use of water at typical Pressurised Water Reactors conditions as coolant. The present WCLL FW with a waved plasma-faced surface and with circular channels was studied and the heat load limit has been predicted with FEM analy…
On the impact of side methyl groups on the structure and vibrational properties of β-carotenoids. The case of butadiene and isoprene
2021
Abstract Theoretical consideration about the impact of methyl groups on the structure and vibrational properties of β-carotenoids, using medium size molecules of trans-butadiene and trans-isoprene, are reported. Density functional theory (DFT) calculations with correlation-consistent and polarization-consistent basis sets were applied to trans-1,3-butadiene and trans-isoprene as the smallest building bricks of β-carotenoids. Their structure and harmonic vibrations were estimated in the complete basis set limit (CBS) using the non-linear least square fit. Optimized geometries and harmonic frequencies, obtained with B3LYP and BLYP density functionals and large basis sets, were favorably repro…
Effect of thermocycling with or without 1 year of water storage on retentive strengths of luting cements for zirconia crowns
2015
Abstract Statement of problem Bond stability between zirconia crowns and luting cement and between cement and dentin is a main concern; however, only limited evidence is available as to its longevity. Purpose The purpose of this in vitro study was to measure the retentive strengths of 7 self-adhesive cements (RelyX Unicem Aplicap, RelyX Unicem Clicker, RelyX Unicem 2 Automix, iCEM, Maxcem Elite, Bifix SE, SpeedCem), 2 adhesive cements with self-etch primers (Panavia 21, SEcure), 1 glass ionomer cement (Ketac Cem), 1 resin-modified glass ionomer cement (Meron Plus), and 1 zinc phosphate cement for luting zirconia crowns (LAVA) to extracted teeth after thermocycling with or without 1 year of …
Speed-accuracy trade-off and its consequences in a scramble competition context.
2014
Abstract: Animals foraging in groups commonly respond to the presence of others by increasing their foraging rate, an increase that could come at the expense of prey detection accuracy. Yet the existence and consequences of such so-called 'speed-accuracy trade-offs' in group-foraging animals remain unexplored. We used group-feeding zebra finches, Taeniopygia guttata, to determine how search speed affects food detection accuracy and how a potential speed-accuracy trade-off influences feeding success. We found significant between-individual differences in hopping speed as well as evidence that faster individuals were more likely to overlook food, demonstrating the existence of a trade-off bet…
Modeling by the finite element method of acoustic radiation in waveguides lined with locally or non locally reacting absorbent materials in the prese…
2011
Our concern in this work is the problem of acoustic propagation in guides lined with locally or non locally reacting materials with the presence of mean fluid flow. In several industrial systems such as aircraft jet engines, mufflers exhaust and ventilation systems, noise is mostly channeled outside by guides of more or less complex geometries. A study of waveguides makes it possible to predict and understand the physical phenomena such as refraction, convection, absorption and wave attenuation. In waveguides studies, guides are often considered infinitely long to get rid of some phenomena (reflection for example) at their ends. Solving the problem of acoustic propagation in infinite guides…
Elaboration and interfacial reactivity of Lanthanum Strontium Chromium Ruthenium (LSCrRu) perovskite oxides as intermediate temperature fuel cell (IT…
2005
New data on the interest of ruthenium doped lanthanum strontium chromite La1-xSrxCr1-yRuyO3δ (LSCrRu) as anode in ITSOFC are presented. Microwave synthesis of mixed oxides allowed shaping of half-cells and complete cells using sputtering and screen printing methods. LSCrRu methane reforming property had been studied in a mono-chamber system coupled with a mass spectrometer in collaboration with Institut de REcherche Hydro-Québec. Anode/electrolyte interfacial reactivity had been analysed using SIMS and XRD on half cells models after ageing under H2 at 800°C. This experiment gave the chemical composition of the film after treatment. Complete cells, tested under working conditions, highlight…
Presentations of constrained systems with unconstrained positions
2005
International audience; We give a polynomial-time construction of the set of sequences that satisfy a finite-memory constraint defined by a finite list of forbidden blocks, with a specified set of bit positions unconstrained. Such a construction can be used to build modulation/error-correction codes (ECC codes) like the ones defined by the Immink-Wijngaarden scheme in which certain bit positions are reserved for ECC parity. We give a lineartime construction of a finite-state presentation of a constrained system defined by a periodic list of forbidden blocks. These systems, called periodic-finite-type systems, were introduced by Moision and Siegel. Finally, we present a linear-time algorithm for con…