Coulomb-potential-dependent decohesion of Magnéli phases.

Transition metal oxide Magnéli phases are traditionally described as crystallographic shear structures. Some of these phases feature a layered crystal structure based on deformed metal-oxygen octahedra. Here, we describe the correlation between structure, decohesion energies and elastic properties of WO(3), ReO(3), MoO(2), VO(2), V(2)O(5) and TiO(2) using ab initio calculations.

Ab initio calculations of the structure and mechanical properties of vanadium oxides.

VO, V(2)O(3), VO(2), V(6)O(13), V(4)O(9), V(3)O(7) and V(2)O(5) have been investigated in terms of structure, bulk modulus B and elastic constant C(44) using ab initio calculations. The C(44) values for V(6)O(13), V(4)O(9), V(3)O(7) and V(2)O(5) are significantly lower than those for V(2)O(3) and VO(2). As the V valency is increased from 3 to 5, C(44) decreases by 83%, whereas the bulk modulus decreases by 61%, leading to an increase in the B/C(44) ratio from 1.

Ba3Li2V2O7Cl4, a new vanadate with a channel structure.

The tribarium dilithium divanadate tetrachloride Ba(3)Li(2)V(2)O(7)Cl(4) is a new vanadate with a channel structure and the first known vanadate containing both Ba and Li atoms. The structure contains four non-equivalent Ba(2+) sites (two with m and two with 2/m site symmetry), two Li(+) sites, two nonmagnetic V(5+) sites, five O(2-) sites (three with m site symmetry) and four Cl(-) sites (m site symmetry). One type of Li atom lies in LiO(4) tetrahedra (m site symmetry) and shares corners with VO(4) tetrahedra to form eight-tetrahedron Li(3)V(5)O(24) rings and six-tetrahedron Li(2)V(4)O(18) rings; these rings are linked within porous layers parallel to the ab plane and contain Ba(2+) and Cl(-) ions.

Immobilized DNA aptamers used as potent attractors for porcine endothelial precursor cells.

Because of their insufficient biocompatibility and high thrombogenicity, small diameter artificial vascular prostheses still do not show a satisfactory patency rate. In vitro endothelialization of artificial grafts before implantation has been established experimentally years ago, but, this procedure is extremely time consuming and expensive. This study deals with the coating of graft surfaces with capture molecules (aptamers) for circulating endothelial progenitor cells (EPCs), mimicking a prohoming substrate to fish out EPCs from the bloodstream after implantation and to create an autologous functional endothelium.

Synthesis and structural characterization of BaV4O9.

The new spin (1/2) V(4+) barium oxovanadate BaV(4)O(9) was synthesized and studied by means of single-crystal X-ray diffraction. Its room-temperature structure is monoclinic, space group P2/c. We discuss the temperature evolution of the crystal structure and thermal expansion tensor of the material between 293 and 100 K.