Interface and electronic characterization of thin epitaxial Co3O4 films

The interface and electronic structure of thin (~20-74 nm) Co3O4(110) epitaxial films grown by oxygen-assisted molecular beam epitaxy on MgAl2O4(110) single crystal substrates have been investigated by means of real and reciprocal space techniques. As-grown film surfaces are found to be relatively disordered and exhibit an oblique low energy electron diffraction (LEED) pattern associated with the O-rich CoO2 bulk termination of the (110) surface. Interface and bulk film structure are found to improve significantly with post-growth annealing at 820 K in air and display sharp rectangular LEED patterns, suggesting a surface stoichiometry of the alternative Co2O2 bulk termination of the (110) surface. Non-contact atomic force microscopy demonstrates the presence of wide terraces separated by atomic steps in the annealed films that are not present in the as-grown structures; the step height of ~ 2.7 A corresponds to two atomic layers and confirms a single termination for the annealed films, consistent with the LEED results. A model of the (1 * 1) surfaces that allows for compensation of the polar surfaces is presented.Comment: 8 pages, 7 figure

Is there a role of coral bone substitutes in bone repair?

Xenogeneic bone graft materials are an alternative to autologous bone grafting. Among such implants, coralline-derived bone grafts substitutes have a long track record as safe, biocompatible and osteoconductive graft materials. In this review, we present the available literature surrounding their use with special focus on the commercially available graft materials. Corals thanks to their chemical and structural characteristics similar to those of the human cancellous bone have shown great potential but clinical data presented to date is ambiguous with both positive and negative outcomes reported. Correct formulation and design of the graft to ensure adequate osteo-activity and resorption appears intrinsic to a successful outcome

État expérimental de la question de l'antiferromagnétisme

Dans son rapport, l'auteur montre, d'une part que les résultats expérimentaux s'interprètent bien en supposant que les interactions négatives entre les ions magnétogènes sont du type indirect de Kramers, qu'elles se font par l'intermédiaire des anions et, d'autre part, que l'étude de l'anisotropie magnétique au-dessous de Tλ permet, dans quelques cas simples, de déterminer la ou les directions d'antiferromagnétisme spontané

Aimantations principales du chlorure et du bromure chromiques

The curves describing as a function of temperature, and for different values of the magnetic field, the principal magnetizations of chromic chloride and bromide show that these compounds are antiferromagnetic below 16.8 and 37.7 °K respectively.Les courbes représentant en fonction de la température, et pour différentes valeurs du champ magnétique, les aimantations principales du chlorure et du bromure chromiques montrent que ces composés sont antiferromagnétiques au-dessous respectivement de 16,8 et 37,7 °K