A Hybrid Ring‐Opening Metathesis Polymerization Catalyst Based on an Engineered Variant of the β‐Barrel Protein FhuA

A β‐barrel protein hybrid catalyst was prepared by covalently anchoring a Grubbs–Hoveyda type olefin metathesis catalyst at a single accessible cysteine amino acid in the barrel interior of a variant of β‐barrel transmembrane protein ferric hydroxamate uptake protein component A (FhuA). Activity of this hybrid catalyst type was demonstrated by ring‐opening metathesis polymerization of a 7‐oxanorbornene derivative in aqueous solution.     

Interactions du rhénium à haute température avec N2O sous basse pression

Starting at room temperature, N20 adsorption on rhenium proceeds dissociatively. Oxygen atoms remain on the surface while nitrogen molecules are desorbed. The overall process is characterized by an initial sticking coefficient value equal to 0.3 at 298 °K. In stationary conditions, and in a higher temperature range (> 1200°K) rhenium trioxide and oxygen atoms are the reaction products, depending on oxygen coverage on the surface. When the oxygen coverage is low, atomization, characterized by a reactive sticking probability of 0.2 is the only observable process. All the results are consistent with a model, previously proposed for the system oxygen-rhenium and oxygen-transition metals. The main differences in reaction rates between rhenium and oxygen or N₂O are interpreted in terms of saturation coverages.     

Radiative lifetime and oscillator strength determinations in potassium ions (K V, K VI and K VII)

Oscillator strengths have been calculated for the transitions depopulating levels of the 3s²3p³, 3s3p⁴ configurations of K V, of the 3s²3p², 3s3p³ configurations of K VI and of the 3s²3p, 3s3p², 3p³ and 3s3p3d configurations of K VII. A multiconfiguration Dirac-Fock method, incorporating the relativistic two-body Breit interaction and quantum electrodynamics corrections due to self-energy and vacuum polarization, has been used for the calculations. The reliability of this approach has been tested by comparison with relativistic Hartree-Fock calculations and also with some experimental measurements performed by beam-foil spectroscopy at a beam energy of 1.7 MeV.     

Comments on the Paper 'Local and Global Transitions to Chaos and Hysteresis in a Porous Layer Heated from Below', by P. Vadasz

Transport in Porous Media -     

RéDUCTION CHIMIQUE ET éLECTROCHIMIQUE DE LA PHéNYL-4 DITHIOLE-1,2 THIONE-3

Abstract

4-phenyl 1.2-dithiole 3-thione gives, after reduction with sodium sulfide or electrochemical reduction at a mercury cathode followed by a methylation, the methyl 3-methylthio 2-phenyl 2-propenedithioate of E configuration. The reduction of the dithiolethione at a platinum cathode gives after methylation a dimer according to a monoelectronic process.

La réduction par le sulfure de sodium ou sur électrode de mercure de la phényl-4 dithiole-1,2 thione-3 conduit, après méthylation, au méthylthio-3 phènyl-2 propène-2 dithioate de méthyle de configuration E. Sur cathode de platine, la dithiolethione étudiée se réduit selon un processus à un électron conduisant après méthylation a un dimère.     

The Baum–Connes Conjecture and Discrete Group Actions on Trees

We introduce a property (BC) for discrete groups, which we prove to imply the Baum–Connes conjecture with coefficients and the K-amenability of the group. Then, we show that if is a discrete group which acts on a tree X such that X/ is compact, and the stabilizers of the vertices and the stabilizers of the edges satisfy (BC), then itself satisfies (BC) Finally, we indicate a couple of applications.     

La conjecture de Baum–Connes pour les feuilletages moyennables

We show, using the construction of Higson and Kasparov, that the Baum–Connes Conjecture holds for foliations whose holonomy groupoid is Hausdorff and amenable. More generally, for every locally compact, -compact and Hausdorff groupoid G acting continuously and isometrically on a continuous field of affine Euclidean spaces, the Baum–Connes conjecture with coefficients is an isomorphism, and G amenable in K-theory. In addition, we show that C^*(G) satisfies the Universal Coefficient Theorem.