Local Lattice Instability and Superconductivity in La1.85_{1.85}Sr0.15_{0.15}Cu1−x_{1-x}Mx_xO4_4 (M=Mn, Ni, and Co)

Local lattice structures of La$_{1.85}$Sr$_{0.15}$Cu$_{1-x}$M$_x$O$_4$ (M=Mn, Ni, and Co) single crystals are investigated by polarized extended x-ray absorption fine structure (EXAFS). The local lattice instability at low temperature is described by in-plane Cu-O bond splitting. We find that substitution of Mn for Cu causes little perturbation of local lattice instability while Ni and Co substitution strongly suppresses the instability. The suppression of superconductivity by Cu-site substitution is related to the perturbation of lattice instability, indicating that local lattice instability (polaron) plays an important role in superconductivity

XANES study of rare-earth valency in LRu4P12 (L = Ce and Pr)

Valency of Ce and Pr in LRu4P12 (L = Ce and Pr) was studied by L2,3-edge x-ray absorption near-edge structure (XANES) spectroscopy. The Ce-L3 XANES spectrum suggests that Ce is mainly trivalent, but the 4f state strongly hybridizes with ligand orbitals. The band gap of CeRu4P12 seems to be formed by strong hybridization of 4f electrons. Pr-L2 XANES spectra indicate that Pr exists in trivalent state over a wide range in temperature, 20 < T < 300 K. We find that the metal-insulator (MI) transition at TMI = 60 K in PrRu4P12 does not originate from Pr valence fluctuation.Comment: 4 page

Nonlocal magnon-polaron transport in yttrium iron garnet

The spin Seebeck effect (SSE) is observed in magnetic insulator|heavy metal bilayers as an inverse spin Hall effect voltage under a temperature gradient. The SSE can be detected nonlocally as well, viz. in terms of the voltage in a second metallic contact (detector) on the magnetic film, spatially separated from the first contact that is used to apply the temperature bias (injector). Magnon-polarons are hybridized lattice and spin waves in magnetic materials, generated by the magnetoelastic interaction. Kikkawa et al. [Phys. Rev. Lett. \textbf{117}, 207203 (2016)] interpreted a resonant enhancement of the local SSE in yttrium iron garnet (YIG) as a function of the magnetic field in terms of magnon-polaron formation. Here we report the observation of magnon-polarons in \emph{nonlocal} magnon spin injection/detection devices for various injector-detector spacings and sample temperatures. Unexpectedly, we find that the magnon-polaron resonances can suppress rather than enhance the nonlocal SSE. Using finite element modelling we explain our observations as a competition between the SSE and spin diffusion in YIG. These results give unprecedented insights into the magnon-phonon interaction in a key magnetic material.Comment: 5 pages, 6 figure

Lattice Instability in High Temperature Superconducting Cuprates and FeAs Systems: Polarons Probed by EXAFS

Carrier-induced lattice distortion (signature of polaron) in oxypnictide superconductors is found by an instantaneous local probe, extended X-ray absorption fine structure (EXAFS). Polaron formation is detected as two distinct nearest neighbor distances (FeAs), implying an incoherent local mode that develops coherence at the critical temperature. Comparing the results with the unusual lattice response in cuprate superconductors, intimate correlation between evolution of local lattice mode and superconductivity is revealed. The results suggest that strong electron-lattice interaction is present as a common ingredient in the microscopic mechanism of superconducting transition. The effect of magnetic impurity atoms in cuprates further indicates that magnetic scattering becomes diluted as long as polaron formation is conserved. We argue that polaron coherence dominates electrical conduction and magnetic interaction in oxypnictide and cuprate superconductors

Relationship Between Macrophage Differentiation And The Chemotactic Activity Toward Damaged Muscle Cells

Aim: We investigated the effect of macrophage differentiation on the chemotactic activity to invade local damaged muscle using in vitro models of muscle injury. Methods: C2C12 cell myoblasts, and J774 cell macrophages were used. The “killed-C2C12” cells were combined with live C2C12 cells (live:killed C2C12 = 1:0.5) as a partially damaged muscle model. The J774 cells were stimulated with LPS and DEX. The chemotactic activity of J774 cells was examined using TAXIScan device. Results: Although the velocity of J774 cells was little affected by each type of C2C12 cells (live, killed and combination), the directionality of the J774 cells was increased. The highest directionality of J774 cells was observed when the ratio of live-:killed-C2C12 cells was 1:0.5.The TLR4 and CD11c expressions of LPS cells were higher than those in both Ctrl and DEX cells. The LPS cells were strongly stained around the cell membrane by phalloidin, but the F-actin expression in DEX cells was in an orderly line along the long axis of cells. DEX cells showed stretching toward C2C12 cells, and their length/width ratio was higher than that in both Ctrl and LPS cells. Although the chemotactic activity of LPS cells disappeared completely, DEX cells exhibited accelerated chemotactic activity toward damaged muscle cells. The MCP-1 production in live-:killed-C2C12 cells was higher than that in the live-C2C12 cells. The CCR2 expression in DEX cells was higher than that in both Ctrl and LPS cells. Conclusion: Our conclusion is that: 1) the chemotactic activity of macrophages toward areas of damaged muscle induces more live myoblasts than damaged cells, 2) the chemotactic activity of macrophages is not due to velocity, but depends on the directionality toward damaged muscle cells, and 3) macrophage differentiation influences their chemotactic activity toward damaged muscle cells through the expression of CCR2 and/or F-actin

Exhaustive Exercise Enhances Immune Response To Flagellin Via Adrenaline-Mediated Up-Regulation of TLR5 Expression

Objective: We already reported that lipopolysacchride (LPS)-induced tumor necrosis factor (TNF)-α production as a bacterial infection model to induce immune response, was inhibited by exhaustive exercise. However, it remains unclear whether or not the immune response to flagellin (FG), which binds to toll like receptor 5(TLR5) and induces pro-inflammatory cytokine production, is also inhibited by this severe exercise. The aim of this study was to determine whether or not exhaustive exercise affects TNF-α productions after FG injection in mice. Methods: Both exhaustive-exercised (EX; n=12) and non-exercised (N-EX; n=12) male C3H/HeN mice were injected with FG (1 mg/kg, i.v), and blood samples were collected. In addition, to clarify the effect of catecholamine on immune response macrophage and intestinal cells after FG stimulation, RAW264 cells and Caco2 cells were cultured 30min after propranolol (Prop; β-adrenergic receptors blocker) or Ly294002 (Ly; PI3K inhibitor) treatments, and were then stimulated with adrenaline (AD; 1 μM) and FG (5 μg/ml). Moreover, the effect of Prop (10 mg/kg, n=12) on FG-induced TNF-α production in EX mice was also examined. Results: TNF-α in EX group was significantly higher than that in N-EX group after FG injection. In epithelium cells, more intensity of TLR5 localization was observed on the plasma membrane area than in the cytosol area in EX mice, but not N-EX mice. Caco2 cells, but not RAW264 cells, significantly increased the FG-induced TNF-α production using AD treatment. Moreover, Prop treatment attenuated the AD-induced TNF-α production in response to FG in Caco2 cells. Although TLR5 expression on RAW264 cells was significantly decreased after AD treatment, the expression on Caco2 cells was rapidly increased. In fact, we observed the AD-dependent TLR5 translocation from cytoplasm to cell membrane in Caco2 cells, and the membrane translocation was inhibited by Prop and Ly treatment. Moreover, the pretreatment with Prop attenuated the exercise-induced plasma TNF-α response to FG in vivo. Conclusion: Our results suggest that immune response to FG via TLR5 might be enhanced by exhaustive exercise in mice

Hadron Masses from the Valence Approximation to Lattice QCD

We evaluate pseudoscalar, vector, spin 1/2 and spin 3/2 baryon masses predicted by lattice QCD with Wilson quarks in the valence (quenched) approximation for a range of different values of lattice spacing, lattice volume and quark mass. Extrapolating these results to physical quark mass, then to zero lattice spacing and infinite volume we obtain values for eight mass ratios. We also determine the zero lattice spacing, infinite volume limit of an alternate set of five quantities found without extrapolation in quark mass. Both sets of predictions differ from the corresponding observed values by amounts consistent with the predicted quantities' statistical uncertainties.Comment: 108 pages of Latex, including 50 PostScript figures, tarred, compressed and uuencoded. IBM-HET-94-3. (The first version of this posting exceeded the size limit. I squeezed the second version in by dropping out the figues. This version gets the figures in but has to be run through Latex and dvips.

Infrared study of spin crossover Fe-picolylamine complex

Infrared (IR) absorption spectroscopy has been used to probe the evolution of microscopic vibrational states upon the temperature- and photo-induced spin crossovers in [Fe(2-picolylamine)3]Cl2EtOH (Fe-pic). To overcome the small sizes and the strong IR absorption of the crystal samples used, an IR synchrotron radiation source and an IR microscope have been used. The obtained IR spectra of Fe-pic show large changes between high-spin and low-spin states for both the temperature- and the photo- induced spin crossovers. Although the spectra in the temperature- and photo-induced high-spin states are relatively similar to each other, they show distinct differences below 750 cm-1. This demonstrates that the photo-induced high-spin state involves microscopically different characters from those of the temperature-induced high-spin state. The results are discussed in terms of local pressure and structural deformations within the picolylamine ligands, and in terms of their possible relevance to the development of macroscopic photo-induced phase in Fe-pic.Comment: 6 pages (text) and 6 figures,submitted to J. Phys. Soc. Jp

Hadron Mass Predictions of the Valence Approximation to Lattice QCD

We evaluate the infinite volume, continuum limits of eight hadron mass ratios predicted by lattice QCD with Wilson quarks in the valence (quenched) approximation. Each predicted ratio differs from the corresponding observed value by less than 6\%.Comment: 13 pages of Latex + 2 PostScript files attached, IBM/HET 92-