A model of multiphase flow and transport in porous media applied to gas migration in underground nuclear waste repository

We prove existence of solutions for a new model of two compressible and partially miscible phase flow in porous media, applied to gas migration in an underground nuclear waste repository. This model, modeling fully and partially water saturated situations, consist of a coupled system of quasilinear parabolic partial differential equations. We seek a new set of variables in order to obtain a system which belongs to the class of equations considered by Alt and Luckhaus such that it would be possible to use their existence theorem. A simulation of a numerical test case is performed in order to numerically demonstrate the ability of this model to take in account the appearance of one phase. To cite this article: F. Smaï, C. R. Acad. Sci. Paris, Ser. I 347 (2009).     

New data about the reaction of benzyolacetonitrile with malononitrile and its self‐condensation

The reactions of benzoylacetonitrile with malononitrile in refluxing pyridine and its self condensation under fusion conditions in the presence of ammonium acetate and in refluxing pyridine were reinvestigated. New data were found and plausible mechanisms to account for the formation of the products are suggested.     

Optical conductivity of a two-dimensional electron liquid with spin-orbit interaction

The interplay of electron-electron interactions and spin-orbit coupling leads to a new contribution to the homogeneous optical conductivity of the electron liquid. The latter is known to be insensitive to many-body effects for a conventional electron system with parabolic dispersion. The parabolic spectrum has its origin in the Galilean invariance which is broken by spin-orbit coupling. This opens up a possibility for the optical conductivity to probe electron-electron interactions. We analyze the interplay of interactions and spin-orbit coupling and obtain optical conductivity beyond RPA.     

Some properties of almost L-weakly and almost M-weakly compact operators

Positivity - In this paper, we investigate necessary and sufficient conditions under which compact operators between Banach lattices must be almost L-weakly compact (resp. almost M-weakly compact)....     

Rational design of a BiFeWO6 nanostructure for supercapacitor applications

Journal of Solid State Electrochemistry - Scientists are increasingly interested in improving electroactive technologies for supercapacitor applications, since energy storage devices have improved...     

Immobilization of palladium nanoparticles as a recyclable heterogeneous catalyst for the Suzuki–Miyaura coupling reaction

This work describes the synthesis of Pd nanoparticles that are stabilized on CaAl-layered double hydroxide functionalized with Tris (tris(hydroxymethyl)aminomethane). The synthesized catalyst is characterized by several different analyses and has been successfully applied to the Suzuki–Miyaura reaction.     

Bonded exciplexes. A new concept in photochemical reactions

Charge-transfer quenching of the singlet excited states of cyanoaromatic electron acceptors by pyridine is characterized by a driving force dependence that resembles those of conventional electron-transfer reactions, except that a plot of the log of the quenching rate constants versus the free energy of electron transfer is displaced toward the endothermic region by 0.5-0.8 eV. Specifically, the reactions with pyridine display rapid quenching when conventional electron transfer is highly endothermic. As an example, the rate constant for quenching of the excited dicyanoanthracene is 3.5 x 10(9) M(-1)s(-1), even though formation of a conventional radical ion pair, A*-D*+, is endothermic by approximately 0.6 eV. No long-lived radical ions or exciplex intermediates can be detected on the picosecond to microsecond time scale. Instead, the reactions are proposed to proceed via formation of a previously undescribed, short-lived charge-transfer intermediate we call a "bonded exciplex", A- -D+. The bonded exciplex can be formally thought of as resulting from bond formation between the unpaired electrons of the radical ions A*- and D*+. The covalent bonding interaction significantly lowers the energy of the charge-transfer state. As a result of this interaction, the energy decreases with decreasing separation distance, and near van der Waals contact, the A- -D+ bonded state mixes with the repulsive excited state of the acceptor, allowing efficient reaction to form A- -D+ even when formation of a radical ion pair A*-D*+ is thermodynamically forbidden. Evidence for the bonded exciplex intermediate comes from studies of steric and Coulombic effects on the quenching rate constants and from extensive DFT computations that clearly show a curve crossing between the ground state and the low-energy bonded exciplex state.