Cell/surface interactions and adhesion on Ti-6Al-4V: Effects of surface texture

This paper presents the results of an experimental study of the effects of surface texture on the interactions between human osteo-sarcoma (HOS) cells and Ti-6Al-4V. These include the Ti-6Al-4V with polished (smooth); Al(2)O(3) blasted (rough); and laser micro-grooved geometries with controlled spacings and depths. Immuno-fluorescence staining of adhesion proteins (actin and vinculin) was used to study the spreading and adhesion of HOS cells in 2 day culture experiments. Quantitative measures of adhesion were also obtained using an enzymatic detachment assay. The results are discussed within the context of existing theories of cell adhesion. The implications of the results are also examined for the design of textured surfaces in biomedical systems.

Superconductivity in the filled cage compounds Ba6Ge25 and Ba4Na2Ge25

The clathrate compound Ba 6Ge25 and its relatives consist of a rigid germanium skeleton, into which barium or other metal atoms are coordinated. These guest atoms can "rattle" freely at high temperatures, but in Ba 6Ge25 some of them lock randomly into split positions below T(S) approximately 200 K. The resulting bad metal undergoes a BCS-like superconducting transition at T(c) approximately 0.24 K. T(c) increases more than 16-fold, as T(S) is suppressed by hydrostatic pressure p, but changes only slightly with p from T(c) approximately 0.84 K in the undistorted sister compound Ba 4Na2Ge25. The large enhancement of T(c) in Ba 6Ge25 may be attributed mainly to the pressure tuning of strong disorder caused by the random displacement of Ba atoms at T(S).

YbRh(2)Si(2): pronounced non-fermi-liquid effects above a low-lyingmagnetic phase transition

We report the first observation of non-Fermi-liquid (NFL) effects in a clean Yb compound at ambient pressure and zero magnetic field. The electrical resistivity and the specific-heat coefficient of high-quality single crystals of YbRh(2)Si(2) present a linear and a logarithmic temperature dependence, respectively, in more than a decade in temperature. We ascribe this NFL behavior to the presence of (presumably) quasi-2D antiferromagnetic spin fluctuations related to a very weak magnetic phase transition at T(N) approximately 65 mK. Application of hydrostatic pressure induces anomalies in the electrical resistivity, indicating the stabilization of magnetic order.