127 research outputs found
Evolution of two-step structural phase transition in Fe1+dTe detected by low-temperature x-ray diffraction
The low-temperature crystal structure of Fe1.13Te, which exhibits an
anomalous two-step magnetic transition, was clarified by the systematic x-ray
diffraction measurements. It was found that two-step structural phase
transition, tetragonal-orthorhombic-monoclinic, occurred correspondingly to the
two-step magnetic transition. The detailed analysis of the profile at 5 K
indicated the coexistence of the minor orthorhombic area inside the major
monoclinic lattice, which could explain the lower-shift (suppression) of the
antiferromagnetic transition temperature in Fe1.13Te and suggest a possibility
of superconductivity at the domain boundary.Comment: 12 pages, 3 figure
Structural and magnetic properties of Fe1+dTe single crystals
We have grown single crystals of Fe1+dTe by a conventional self-flux method.
We obtained plate-like single crystals with dnom \geq 0.1. The value of the
magnetization increased with increasing excess Fe concentration, and a
broadening of the antiferromagnetic transition was observed for dnom >1.15.
Further, we noted that the antiferromagnetic transition of Fe1.134Te (dnom =
0.15) was clearly suppressed to a lower temperature, which would indicate a
possibility of controllability of magnetism by excess Fe concentration.Comment: 6 pages, 4 figures. Submitted to ISS 2011 proceedin
Molecular dynamics study on condensation/evaporation coefficients of chain molecules at liquid-vapor interface
The structure and thermodynamic properties of the liquid–vapor interface are of fundamental interest for numerous technological implications. For simple molecules, e.g., argon and water, the molecular condensation/evaporation behavior depends strongly on their translational motion and the system temperature. Existing molecular dynamics (MD) results are consistent with the theoretical predictions based on the assumption that the liquid and vapor states in the vicinity of the liquid–vapor interface are isotropic. Additionally, similar molecular condensation/evaporation characteristics have been found for long-chain molecules, e.g., dodecane. It is unclear, however, whether the isotropic assumption is valid and whether the molecular orientation or the chain length of the molecules affects the condensation/evaporation behavior at the liquid–vapor interface. In this study, MD simulations were performedto study the molecular condensation/evaporation behavior of the straight-chain alkanes, i.e., butane,octane, and dodecane, at the liquid–vapor interface, and the effects of the molecular orientationand chain length were investigated in equilibrium systems. The results showed that the condensation/evaporation behavior of chain molecules primarily depends on the molecular translational energyand the surface temperature and is independent of the molecular chain length. Furthermore, the orientation at the liquid–vapor interface was disordered when the surface temperature was sufficientlyhigher than the triple point and had no significant effect on the molecular condensation/evaporation behavior. The validity of the isotropic assumption was confirmed, and we conclude that the condensation/evaporation coefficients can be predicted by the liquid-to-vapor translational length ratio, even for chain molecules
The Molecular Pathogenesis and Clinical Implications of Hepatocellular Carcinoma
The prognosis of hepatocellular carcinoma (HCC) is affected by tumoral factors and liver functions; therefore it is often difficult to select the appropriate therapeutic methods for HCC. Recently, two global phase III trials showed that sorafenib, which is a tyrosine kinase inhibitor, improved the prognosis of patients with advanced HCC. As a new therapeutic strategy for HCC, sorafenib is expected to expand the indication for HCC in the future. However, it alone is insufficient for the molecular-targeted treatment of HCC because the signaling pathway exists not only in cancer cells but also in normal cells. Recently, cancer stem cells (CSCs) have attracted attention as a novel therapeutic target for HCC. There is now much evidence that stem cell properties such as self-renewal, unlimited proliferation, and differentiation are highly relevant to cancer recurrence and the drug resistance of HCC. In this review, we describe the molecular pathogenesis and the current state and future development of molecular- and CSC-therapeutic targeted agents for HCC, citing various reports
Evolution of tetragonal phase in the FeSe wire fabricated by a novel chemical-transformation PIT process
We fabricated superconducting FeSe wires by the chemical-transformation PIT
process. The obvious correlation between annealing temperature and phase
transformation was observed. Annealing above 500^{\circ}C produced wire-core
transformation from hexagonal to tetragonal phase. Furthermore the hexagonal
phase completely transformed into the tetragonal phase by annealing at
1000^{\circ}C. With increasing annealing temperature, the superconducting
property was dramatically improved, associated with the evolution of the
tetragonal phase.Comment: 14 pages, 6 figure
Pressure effects on FeSe family superconductors
We investigated the pressure effects on the FeSe superconductor and the
related compounds. Pressure dependence of superconducting transition
temperature (Tc) for FeSe0.8S0.2 exhibits a dome-shaped behavior below 0.76
GPa. On the other hand, the Tc of FeSe0.25Te0.75 linearly increases up to 0.99
GPa. Here we discuss the relation between the physical pressure effects and the
chemical pressure effects on the FeSe system.Comment: 8 pages, 5 figures, proceedings of the 2009 M2S conferenc
Fabrication of the iron-based superconducting wire using Fe(Se, Te)
We have fabricated the Fe(Se, Te) superconducting wire by a special process
based on a powder-in-tube method. The pure Fe tube plays the role of not only
the sheath but also the raw material for synthesizing the superconducting
phases. We succeeded in observing zero resistivity current on the
current-voltage measurements for the Fe(Se, Te) wire. Introduction of the
pinning centers and fabricating a multi-core wire will enhance the critical
current density for the next step.Comment: 16 pages, 6 figures, to appear in Applied Physics Express (APEX
Pressure study of the new iron-based superconductor K0.8Fe2Se2
We investigated pressure effects on transition temperature (Tc) of the new
iron-based superconductor K0.8Fe2Se2 using a BeCu/NiCrAl hybrid-type clamped
piston-cylinder cell. The Tc(onset) was 33K at 0.85 GPa. With increasing
pressure, Tc(onset) gradually increased and reached 36.6 K at 2.03 GPa.Comment: 8 pages, 3 figure
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