Search results for "Roche"
showing 10 items of 2666 documents
Estimation des dimensions en présence d'erreurs
2018
Journées du GDR Analyse Multifractale, Nouan-le-Fuzelier, FRANCE, 16-/09/2018 - 20/09/2018; Nous nous posons la question de l'estimation des différentes dimensions fractales lorsque nous sommes en présence de bruit additif (à une itération donnée) ou multiplicatif ( qui se propage à travers les itérations), en testant, sur des fractales construites, les méthodes classiques d'estimation et en analysant la structure des résidus d'estimation.
Impedance investigation of BaCe0.85Y0.15O3-delta properties for hydrogen conductor in fuel cells
2012
International audience; The influence of the sintering conditions on the electrochemical properties of the proton conducting electrolyte BaCe0.85Y0.15O3-delta (BCY15) and Ni - based BCY15 cermet anode for application in high temperature proton conducting fuel cell are investigated by electrochemical impedance spectroscopy. The results show that at lower sintering temperatures due to the formation of parasitic Y2O3 phase an increase of both the electrolyte and electrode resistances is observed. This effect is strongly reduced by enhancement of the sintering temperature. The obtained BCY15 conductivity (sigma = 2.5x10(-2) S/cm at 700 degrees C) is comparable with that of the best proton condu…
A semiempirical correlation between the optical band gap of hydroxides and the electronegativity of their constituents
2000
In analogy with previous results on anhydrous oxides, a correlation is proposed between the optical band gap of hydroxides and the electronegativities of their constituents. Based on the experimental results on passive hydrated layers on metals obtained in our laboratory and the literature data, it is found that the hydroxide band gap varies with the square of the difference between the electronegativities of the metallic cation and the hydroxyl group. Like in the case of anhydrous oxides, two different interpolation lines have been found forsp-metal andd-metal hydroxides, respectively. The proposed correlations predict semiconducting or insulating behavior even for the most electronegative…
Efficient Benzodithiophene/Benzothiadiazole-Based n-Channel Charge Transporters
2017
A series of donor–acceptor (D-A) small molecules based on electron-deficient benzothiadiazole (BTD) and electron-rich benzodithiophene (BDT) featuring an A-D-A structure is presented. Exhaustive spectroscopic, electrochemical, and computational studies evidence their electroactive nature and their ability to form well-ordered thin films with broad visible absorptions and low band gaps (ca. 2 eV). Time-resolved microwave conductivity (TRMC) studies unveil unexpected n-type charge transport displaying high electron mobilities around 0.1 cm2 V−1 s−1. Efficient electron transport properties are consistent with the low electron reorganization energies (0.11–0.17 eV) theoretically predicted.
Acid-Base Properties of 2:1 Clays. I. Modeling the Role of Electrostatics
2010
We present a theoretical investigation of the titratable charge of clays with various structural charge (sigma(b)): pyrophyllite (sigma(b) = 0 e x nm(-2)), montmorillonite (sigma(b) = -0.7 e x nm(-2)) and illite (sigma(b) = -1.2 e x nm(-2)). The calculations were carried out using a Monte Carlo method in the Grand Canonical ensemble and in the framework of the primitive model. The clay particle was modeled as a perfect hexagonal platelet, with an "ideal" crystal structure. The only fitting parameters used are the intrinsic equilibrium constants (pK(0)) for the protonation/deprotonation reactions of the broken-bond sites on the lateral faces of the clay particles, silanol, =SiO(-) + H(+) --=…
Influence of uniaxial pressure and aging on dielectric and ferroelectric properties of BaTiO3ceramics
2013
The effect of uniaxial pressure (0–3000 bar) applied parallel to the AC electric field and aging on dielectric and ferroelectric behavior of BaTiO3 ceramics were investigated. Applying uniaxial pressure leads to a reduction of the peak intensity of the electric permittivity (e) of the polarization as well as of the dielectric hysteresis. The peak intensity of e becomes diffused and shifts to a higher temperatures with increasing the pressure. The electrostrictive coefficient Q 11 and differential permittivity were evaluated from the obtained data. We interpreted our results based on the hardening of the soft-mode and domain switching processes under the action of pressure. The aging effect …
Carbon-Coated Anatase TiO2Nanotubes for Li- and Na-Ion Anodes
2014
aInstitute of Physical Chemistry and MEET Battery Research Centre, University of Muenster, 48149 Muenster, Germany bHelmholtz-Institute Ulm (HIU), Electrochemistry I, 89081 Ulm, Germany cKarlsruher Institute of Technology (KIT), 76021 Karlsruhe, Germany dInstitute for Organic Chemistry, University of Mainz, 55128 Mainz, Germany eGraduate School Materials Science in Mainz, 55128 Mainz, Germany fInstitute for Inorganic and Analytical Chemistry, University of Mainz, 55128 Mainz, Germany gMax Planck Institute for Polymer Research, 55128 Mainz, Germany
Economic impact of medium-scale battery storage systems in presence of flexible electricity tariffs for end-user applications
2012
This article addresses the question if it is cost-effective to use medium-scale battery storage systems for time-of-use (TMO) energy cost applications at a consumer level, assuming flexible electricity tariffs in the Italian electricity market. TMO application allows customers to reduce their electricity bill charging the storage when off-peak time periods are applied and discharge it during on-peak periods, when electricity energy prices are high. The analysis is carried out taking into account three different electrochemical storage technologies. The economical comparison shows that, at the current costs of storage technologies and at the electricity tariffs currently offered in Italy, th…
The Thermodynamics of Insertion Electrochemical Electrodes—A Team Play of Electrons and Ions across Two Separate Interfaces
2018
Insertion electrochemical electrodes exhibit simultaneous electron and ion transfer, with the two transfers proceeding across different interfaces. Herein the thermodynamics of the overall electrochemical electrode reaction is discussed with respect to the thermodynamics of these two charge-transfer equilibria. This Minireview includes insertion electrochemical systems where the redox centers are in a solid phase and the ions are transferred between that phase and a solution, and also systems where the redox centers are in a liquid phase that is immiscible with another liquid phase and ions are transferred between the two liquid phases. The Minireview is intended to spark similar studies on…
Electrostatic Anchoring of Mn4 Single-Molecule Magnets onto Chemically Modified Multiwalled Carbon Nanotubes
2012
Two different routes that enable the electrostatic grafting of cationic single-molecule magnets (SMMs) onto the surface of chemically modified anionic multi-walled carbon nanotubes (MWNTs) are described. The chemical nature and physical properties of the resulting hybrids are discussed on the basis of a complete battery of experimental techniques. The data show that the chemical nature of the SMM unit remains intact, while its magnetic response is significantly affected by the grafting process, which is likely due to surface effects.