Physical properties of thermoelectric zinc antimonide using first-principles calculations

We report first principles calculations of the structural, electronic, elastic and vibrational properties of the semiconducting orthorhombic ZnSb compound. We study also the intrinsic point defects in order to eventually improve the thermoelectric properties of this already very promising thermoelectric material. Concerning the electronic properties, in addition to the band structure, we show that the Zn (Sb) crystallographically equivalent atoms are not exactly equivalent from the electronic point of view. Lattice dynamics, elastic and thermodynamic properties are found to be in good agreement with experiments and they confirm the non equivalency of the zinc and antimony atoms from the vibrational point of view. The calculated elastic properties show a relatively weak anisotropy and the hardest direction is the y direction. We observe the presence of low energy modes involving both Zn and Sb atoms at about 5-6 meV, similarly to what has been found in Zn4Sb3 and we suggest that the interactions of these modes with acoustic phonons could explain the relatively low thermal conductivity of ZnSb. Zinc vacancies are the most stable defects and this explains the intrinsic p-type conductivity of ZnSb.Comment: 33 pages, 8 figure

Multimodal prevention of venous thromboembolic complications after total hip and knee joint endoprosthesis

Results of a study of the efficacy and safety of multimodal prevention of venous thromboembolic complications (VTEC) after total knee and hip joint replacement in 1623 patients are presented. Two studies were carried out: the first focused on determining patient preference for the route of administration (parenteral or oral) for the prevention of VTEC. The second study analyzed the efficacy and safety of postoperative drug prevention of VTEC in routine clinical practice. In both studies the prophylaxis was conducted in accordance with local protocols. The results demonstrate great potential of the modern methods of VTEC prevention and efficiency of new oral medications. The incidence of thromboembolic complications can be reduced through systematic compliance with the protocol