Selenium Supplementation of Layer Diets Based on Milo and Soybean Meal

Previous studies with com-soy diets have shown laying hens to have improved feed efficiency when the diets were supplemented with up to 2 ppm selenium. In some cases, egg production was Improved, but in most instances feed intake was simply reduced without causing a decrease in egg numbers. A study was therefore conducted with a milo-soy diet to further evaluate this treatment

Histoire de la géographie française de 1870 à nos jours

Le contenu de l’ouvrage correspond en fait au titre du livre d’A. Meynier, Histoire de la pensée géographique en France, publié en 1969. Mais Paul Claval nous offre ici un historique épistémologique de la discipline, plus complet (pas seulement plus récent), plus ambitieux et, sans doute, aussi et surtout, plus personnel. L’auteur occupe en effet, une place essentielle, sinon centrale, dans la géographie française des quarante dernières années : en témoigne une production abondante, mais d’un..

Numerical computation of critical properties and atomic basins from three-dimensional grid electron densities

Claudine Katan ‘s present address : CNRS UMR6082 FOTON, INSA de Rennes, 20 avenue des Buttes de Coësmes, CS 70839, 35708 RENNES cedex 7, FranceInternational audienceInteGriTy is a software package that performs topological analysis following the AIM (atoms in molecules) approach on electron densities given on three-dimensional grids. Tricubic interpolation is used to obtain the density, its gradient and the Hessian matrix at any required position. Critical points and integrated atomic properties have been derived from theoretical densities calculated for the compounds NaCl and TTF-(2,5)Cl(2)BQ (tetrathiafulvalene-2,5-dichlorobenzoquinone), thus covering the different kinds of chemical bonds: ionic, covalent, hydrogen bonds and other intermolecular contacts

Neutral-ionic phase transition : a thorough ab-initio study of TTF-CA

The prototype compound for the neutral-ionic phase transition, namely TTF-CA, is theoretically investigated by first-principles density functional theory calculations. The study is based on three neutron diffraction structures collected at 40, 90 and 300 K (Le Cointe et al., Phys. Rev. B 51, 3374 (1995)). By means of a topological analysis of the total charge densities, we provide a very precise picture of intra and inter-chain interactions. Moreover, our calculations reveal that the thermal lattice contraction reduces the indirect band gap of this organic semi-conductor in the neutral phase, and nearly closes it in the vicinity of the transition temperature. A possible mechanism of the neutral-ionic phase transition is discussed. The charge transfer from TTF to CA is also derived by using three different technics.Comment: 11 pages, 9 figures, 7 table

Designing a new two-dimensional molecular layout by hydrogen bonding

Claudine Katan ‘s present address : CNRS UMR6082 FOTON, INSA de Rennes, 20 avenue des Buttes de Coësmes, CS 70839, 35708 RENNES cedex 7, FranceInternational audienceDesigning a New Two-Dimensional Molecular Layout by Hydrogen Bondin

Intramolecular Electronic Redistribution Coupled to Hydrogen Bonding: An Important Mechanism for the "Neutral-to-Ionic" Transition

International audienceThe part played by the electronic interactions in the uncommon "neutral-to-ionic" (N-I) structural transition occurring in some mixed stack organic compounds, such as tetrathiafulvalene-chloranil (TTF-CA), is analyzed by ab initio electronic structure calculations. It is shown that the charge-transfer variation occurring in the valence band along the mixed stacks of donor and acceptor molecules is coupled via an intramolecular mechanism to a deformation of the electronic cloud in lower bands. The lower bands affected by this redistribution are also those which are implicated in the interstack hydrogen bonds, and a charge-transfer increase produces a strengthening of these hydrogen bonds. This important mechanism, which associates the charge-transfer variation to the anisotropic lattice contractions in the crystal, has never been considered up to now

Theoretical Investigation of the Ground-State Properties of DMTTF−CA: A Step toward the Understanding of Charge Transfer Complexes Undergoing the Neutral-to-Ionic Phase Transition

International audienceA detailed theoretical study based on first-principles DFT calculations is reported for the charge transfer complex 2,6-dimethyltetrathiafulvalene-p-chloranil (DMTTF−CA). Charge transfer estimates reveal that no periodic ordering of neutral and ionic layers is obtained in the low-temperature phase of DMTTF−CA. Similarities and differences with other mixed-stack charge transfer complexes are discussed with the help of a topological analysis of the electron density. Our results also show that the most popular model in this field, which is based on the balance between the cost of ionization and the gain in Madelung energy, should be used with great care. These molecules are far from being point charges, and molecular deformation and polarization should not be ignored