Perspective from a Hubbard U-density corrected scheme towards a spin crossover-mediated change in gas affinity.

By employing a recently proposed Hubbard U density-corrected scheme within density functional theory, we provide design principles towards the design of materials exhibiting a spin crossover-assisted gas release. Small molecular fragments are used as case study to identify two main mechanisms behind the change in binding energy upon spin transitions. The feasibility of the proposed mechanism in porous crystals is assessed by correlating the change in binding energy of CO2, CO, N2, and H2, upon spin crossover, with the adiabatic energy difference associated with the spin state change of the square-planar metal in Hofmann-type clathrates (M = Fe, Mn, Ni). A few promising cases are identified for the adsorption of intermediate ligand field strength molecules such as N2 and H2. The latter stands out as the most original result as the strong interaction in low spin, as expected from a Kubas mechanism, results in a large change in binding energy. This work provides a general perspective towards the engineering of open-metal site frameworks exhibiting local environments designed to have a spin crossover upon adsorption of specific gas molecules.

A first-principles study of the effect of charge doping on the 1D polymerization of C(60).

We study the interplay between charge doping and intermolecular distance in the polymerization of C(60) fullerene chains by means of density functional theory-based first-principles calculations. The potential energy surface analysis shows that both the equilibrium intermolecular distance of the unpolymerized system and the polymerization energy barrier are inversely proportional to the electron doping of the system. We analyze the origin of this charge-induced polymerization effect by studying the behavior of the system's wavefunctions around the Fermi level and the structural modifications of the molecules as a function of two variables: the distance between the centers of the molecules and the number of electrons added to the system.

[Contribution of Three-phase Scintigraphy to Indication of Revision Arthroplasty of the Hip Joint.]. / Prínos trojfázovej scintigrafie pre indikáciu k revíznej artroplastike bedrového klbu.

In the introduction of the paper the authors abalyze the problem of stable and long-term fixation of endoprostheses of the hip joint. They present statistics on the ratio of surgical revisions of endoprostheses of the hip joint in 1993-1996 which has a rising trend. In the subsequent part of the paper they deal with the problem of early diagnosis of loosening in the stage when only subjective data reported by the patient are available and the X-ray finding does not yet show signs of osteolysis and loosening of the TEP. Therefore they started to use in 1993 as a diagnostic aid three-phase all-skeletal scintigraphy. So far they used it in 18 patients with 100% reliability, as confirmed on operation. The authors describe in detail the method of three-phase scintigraphy with special emphasis on phase III. The results of scintigraphy are demonstrated on two patients. Key words: revision of endoprosthesis of the hip joint, radiopharmaceutical preparations, 99mTc-MDP, all-skeletal three-phase scintigraphy.