Contactless measurement of electrical conductivity for bulk nanostructured silver prepared by high-pressure torsion: A study of the dissipation process of giant strain

We measured the electrical conductivity of bulk nanostructured silver prepared by high-pressure torsion (HPT) in a contactless manner by observing the AC magnetic susceptibility resulting from the eddy current, so that we could quantitatively analyze the dissipation process of the residual strain with sufficient time resolution as a function of temperature T and initial shear strain γ. The HPT process was performed at room temperature under a pressure of 6 GPa for revolutions N = 0–5, and we targeted a wide range of residual shear strains. The contactless measurement without electrode preparation enabled us to investigate both the fast and slow dissipation processes of the residual strain with sufficient time resolution, so that a systematic study of these processes became possible. The changes in the electrical conductivity as a function of N at room temperature were indeed consistent with changes in the Vickers microhardness; furthermore, they were also related to changes in structural parameters such as the preferred orientation, the interplanar distance, and the crystallite size. The dissipation process at N = 1, corresponding to γ ≈ 30, was the largest and the fastest. For N = 5, corresponding to γ ≈ 140, we considered the effects of grain boundaries, as well as those of dislocations. The strain dissipation was quite slow below T = 290 K. According to the analytical results, it became successful to conduct the quantitative evaluation of the strain dissipation at arbitrary temperatures: For instance, the relaxation times at T = 280 and 260 K were estimated to be 3.6 and 37 days, respectively

High-pressure dc magnetic measurements on a bisdiselenazolyl radical ferromagnet using a vibrating-coil SQUID magnetometer

The high-pressure magnetic properties of the iodo-substituted bisdiselenazolyl radical ferromagnet IBPSSEt have been studied by vibrating-coil SQUID magnetometry. The magnetic state at a pressure (P) of approximately 2 GPa has the highest Curie temperature (TC) of 27.5 K, and displays an ideal three-dimensional (3D) ferromagnetic interaction network. The value of TC observed by ac magnetic susceptibility measurements is consistent with that obtained from dc measurements below approximately 4 GPa. Field-cooled dc measurements at more elevated pressures reveal a slow evolution of magnetic ordering, so that atP >6 GPa the structure may be described in terms of a 1D ferromagnetic chain with predominantly antiferromagnetic lateral (interchain) interactions, in accord with the results of density functional theory calculations

Prediction of Metastasis and Recurrence in Colorectal Cancer Based on Gene Expression Analysis: Ready for the Clinic?

cancer

FGF18 is required for normal cell proliferation and differentiation during osteogenesis and chondrogenesis

Fibroblast growth factor (FGF) signaling is involved in skeletal development of the vertebrate. Gain-of-function mutations of FGF receptors (FGFR) cause craniosynostosis, premature fusion of the skull, and dwarfism syndromes. Disruption of Fgfr3 results in prolonged growth of long bones and vertebrae. However, the role that FGFs actually play in skeletal development in the embryo remains unclear. Here we show that Fgf18 is expressed in and required for osteogenesis and chondrogenesis in the mouse embryo. Fgf18 is expressed in both osteogenic mesenchymal cells and differentiating osteoblasts during calvarial bone development. In addition, Fgf18 is expressed in the perichondrium and joints of developing long bones. In calvarial bone development of Fgf18-deficient mice generated by gene targeting, the progress of suture closure is delayed. Furthermore, proliferation of calvarial osteogenic mesenchymal cells is decreased, and terminal differentiation to calvarial osteoblasts is specifically delayed. Delay of osteogenic differentiation is also observed in the developing long bones of this mutant. Conversely, chondrocyte proliferation and the number of differentiated chondrocytes are increased. Therefore, FGF18 appears to regulate cell proliferation and differentiation positively in osteogenesis and negatively in chondrogenesis