Search

Author(s): T. Frigge [1]; B. Hafke [1]; T. Witte [1]; B. Krenzer [1]; C. Streubhr [1]; A. Samad Syed [1]; V. Miki Trontl [1]; I. Avigo [1]; P. Zhou [1]; [...]

Indium on silicon (111) exhibits a Peierls-like phase transition from a (4×1) reconstructed high-temperature phase to a (8×2) reconstructed ground state. A controversial debate is going on what kind of phase transition it is: first- or second-order. We employed high-resolution low-energy electron diffraction under slow thermal heating and cooling cycles to follow the phase transition. A robust hysteresis of diffraction spot intensities with a width of 8.6 K has been observed, which is independent of the heating and cooling rate. This hysteresis directly proves the existence of an energy barrier at the phase transition temperature and thus the first-order behavior of this phase transition. [ABSTRACT FROM AUTHOR]

Purpose: In autologous osteochondral transplantation, the edges of the harvested plug are particularly susceptible to mechanical or thermal damage to the chondrocytes. We hypothesised that the applied harvesting device has an impact on chondrocyte vitality., Methods: Both knees of five blackhead sheep (ten knees) underwent open osteochondral plug harvesting with three different circular harvesting devices (osteoarticular transfer system harvester [OATS; diameter 8 mm; Arthrex, Munich, Germany], diamond cutter [DC; diameter 8.35 mm; Karl Storz, Tuttlingen, Germany] and hollow reamer with cutting crown [HRCC; diameter 7 mm; Dannoritzer, Tuttlingen, Germany]) from distinctly assigned anatomical sites of the knee joint. The rotary cutters (DC and HRCC) were either used with (+) or without cooling (-). Surgical cuts of the cartilage with a scalpel blade were chosen as control method. After cryotomy cutting, chondrocyte vitality was assessed using fluorescence microscopy and a Live/Dead assay., Results: There were distinct patterns of chondrocyte vitality, with reproducible accumulations of dead chondrocytes along the harvesting edge. No statistical difference in chondrocyte survivorship was seen between the OATS technique and the control method, or between the HRCC+ technique and the control method (P > 0.05). The DC+, HRCC- and DC- techniques yielded significantly lower chondrocyte survival rates compared with the control method (P < 0.05)., Conclusions: Chondrocyte survival in osteochondral cylinders depends on the applied harvesting technique. The use of rotary cutters without cooling yielded worst results, while the traditional OATS punch and rotary cutters with cooling achieved comparable rates of chondrocyte vitality.