425 research outputs found
Expression of lumican related to CD34 and VEGF in the articular disc of the human temporomandibular joint
Lumican belongs to the small leucine-rich repeat proteoglycan (SLRP) gene family and has been reported to exist in the cornea, intervertebral disc and tendon. Lumican plays a significant role in the assembly and regulation of collagen fibres. The human temporomandibular joint (TMJ) disc is made up of fibrocartilage with an extracellular matrix (ECM) composed of collagen and proteoglycans. The existence and behaviour of lumican have not been studied in the human TMJ disc. Therefore, we used immunohistochemical methods to detect lumican, CD34 and vascular endothelial growth factor (VEGF) and histochemical staining with toluidine blue in 13 human TMJ specimens (10 surgically removed and 3 obtained from autopsy). In both normal and deformed discs we observed staining with toluidine blue. We found that the area of metachromasia inside the deformed disc was uneven and expression of lumican was strong in the areas negative for metachromasia. Staining of VEGF and CD34 inside the deformed disc was seen. We confirmed the expression of lumican in the human TMJ disc and showed that a large number of fibroblast-like cells existed in the area of strong lumican expression. These new findings about the behaviour of lumican suggest that it may play a key role in the generation of a new collagen network by fibroblast-like cells
Incommensurate spin correlations induced by magnetic Fe ions substituted into overdoped Bi1.75Pb0.35Sr1.90CuO6+z
Spin correlations in the overdoped region of Bi1.75Pb0.35Sr1.90CuO6+z have
been explored with Fe-doped single crystals characterized by neutron
scattering, muon-spin-rotation (muSR) spectroscopy, and magnetic susceptibility
measurements. Static incommensurate spin correlations induced by the Fe spins
are revealed by elastic neutron scattering. The resultant incommensurability
delta is unexpectedly large (~0.2 r.l.u.), as compared with delta ~ 1/8 in
overdoped superconductor La2-xSrxCuO4. Intriguingly, the large delta in this
overdoped region is close to the hole concentration p. This result is
reminiscent of the delta ~ p trend observed in underdoped La2-xSrxCuO4;
however, it is inconsistent with the saturation of delta in the latter compound
in the overdoped regime. While our findings in Fe-doped
Bi1.75Pb0.35Sr1.90CuO6+z support the commonality of incommensurate spin
correlations in high-Tc cuprate superconductors, they also suggest that the
magnetic response might be dominated by a distinct mechanism in the overdoped
region.Comment: 4 pages, 5 figures. Revision in introduction, discussion, and
conclusion
Simple Real-Space Picture of Nodeless and Nodal s-wave Gap Functions in Iron Pnictide Superconductors
We propose a simple way to parameterize the gap function in iron pnictides.
The key idea is to use orbital representation, not band representation, and to
assume real-space short-range pairing. Our parameterization reproduces fairly
well the structure of gap function obtained in microscopic calculation. At the
same time the present parameterization is simple enough to obtain an intuitive
picture and to develop a phenomenological theory. We also discuss
simplification of the treatment of the superconducting state.Comment: 4 page
Studies of Impurity-Doping Effects and NMR Measurement5s of La1111 and/or Nd 1111 Fe-Pnictide Superconductors
Measurements of the electrical resistivities, Hall coefficients,
thermoelectric powers, electronic specific heat coefficients have been carried
out for samples of LnFe1-yMyAsO1-xFx (Ln=La, Nd; M=Co, Mn; x=0.11) obtained by
M atom dopings to the superconducting LnFeAsO1-xFx (Ln1111) system. The NMR
longitudinal relaxation rates 1/T1 have also been measured for samples of
LaFe1-yCoyAsO1-xFx with various x values. Co atoms doped to the superconducting
LnFeAsO1-xFx are nonmagnetic, and the Tc-suppression by the Co atoms has been
found to be too weak to understand by the pair breaking effect expected for the
S+- superconducting symmetry proposed as the most probable one for the system.
It throws a serious doubt whether the symmetry is realized in this system.
Instead of the pair breaking, two mechanisms of the Tc-suppression by the doped
impurities have been found: One is the electron localization, which appears
when the sheet resistance exceeds h/4e2=6.45 kohm, and another is the
disappearance or reduction of the hole-Fermi-surfaces around the gamma point in
the reciprocal space. The latter mechanism has been observed, when the electron
number increases with increasing Co-doping level and the system changes from an
anomalous metal to an ordinary one. On the two distinct T dependences of 1/T1
of LaFeAsO1-xFx, 1/T1 T6 reported by our group in the T region from Tc to ~0.4
Tc for samples with the highest Tc values with varying x, and 1/T1 T2.5-3.0
observed by many groups in the almost entire T region studied below Tc, we
discuss what the origin of the difference is, and show that, at least, the
T2.5-3.0-like dependence of 1/T1 cannot be considered as the experimental
evidence for the S+- symmetry of the order parameter.Comment: 11 pages, 14 figures, accepted for publication in J. Phys. Soc. Jpn.,
Fig. 14 adde
Multigap superconductivity in sesquicarbides LaC and YC
A complex structure of the superconducting order parameter in C
( = La, Y) is demonstrated by muon spin relaxation (SR) measurements
in their mixed state. The muon depolarization rate []
exhibits a characteristic temperature dependence that can be perfectly
described by a phenomenological double-gap model for nodeless
superconductivity. While the magnitude of two gaps is similar between
LaC and YC, a significant difference in the interband coupling
between those two cases is clearly observed in the behavior of .Comment: 5 pages, 4 figure
To What Extent Iron-Pnictide New Superconductors Have Been Clarified: A Progress Report
In this review, the authors present a summary of experimental reports on
newly discovered iron-based superconductors as they were known at the end of
2008. At the same time, this paper is intended to be useful for experimenters
to know the current status of these superconductors. The authors introduce
experimental results that reveal basic physical properties in the normal and
superconducting states. The similarities and differences between iron-pnictide
superconductors and other unconventional superconductors are also discussed.Comment: 20 pages, 32 figures. Open selec
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