Hall coefficient of La1.88−y_{1.88-y}Yy_ySr0.12_{0.12}CuO4_4 (y=0,0.04y=0, 0.04) at low temperatures under high magnetic fields

The Hall coefficient in the low-temperature tetragonal phase and the mid-temperature orthorhombic phase of La$_{1.88-y}$Y$_y$Sr$_{0.12}$CuO$_4$ ($y=0, 0.04$) single crystals is measured under high magnetic fields up to 9 T in order to investigate the detailed behavior of the transport properties at low temperatures in the stripe phase. When the superconductivity is suppressed by high magnetic fields, the Hall coefficient has negative values in low temperatures, and the temperature region of the negative values spreads as increasing magnetic fields. This result indicates that the Hall coefficient in the stripe phase around $x=0.12$ is a finite negative value, not zero.Comment: 4 pages, 4 figures. to be published to Physical Review

Bio-inspired domino reduction of nitroarenes by acrolein-amine conjugates in one-pot operation

© 2017 The Chemical Society of Japan.Biologically relevant amines react with acrolein to provide 3-formyl-3,4-dehydropiperidine (FDP) as the oxidative stress product, which has reduction potential via hydrogen transfer. This biogenic process was applied to the domino reduction of electron-deficient nitroarenes in one-pot operation, by simply mixing primary amine, acrolein, nitroarene, and calcium chloride. The reaction can be performed in a gram-scale without the use of hazardous metals

Imino [4+4] cycloaddition products as exclusive and biologically relevant acrolein-amine conjugates are intermediates of 3-formyl-3,4-dehydropiperidine (FDP), an acrolein biomarker

© 2014 Elsevier Ltd. All rights reserved. We demonstrated synthetically that the eight-membered heterocycles 2,6,9-triazabicyclo[3.3.1]nonanes and 1,5-diazacyclooctanes are the initial and exclusive products of the reaction, through an imino [4+4] cycloaddition, of biologically relevant amines with acrolein. The stabilities of the aminoacetals within the eight-membered heterocycles determined whether the product was subsequently transformed gradually into the 3-formyl-3,4-dehydropiperidine (FDP), which is widely used as an oxidative stress marker. The reactivity profiles discovered in this study suggested that some of the imino [4+4] cycloaddition products are reactive intermediates of FDP and contribute to the mechanisms underlying the oxidative stress response to acrolein

Highly Strengthened Superconducting Magnet for a 40 T Compact Hybrid Magnet(Magnet Technology)

A 16 T outer superconducting magnet for a 40 T compact hybrid magnet is investigated. A highly strengthened superconducting magnet with a 360 mm room temperature bore can be made using newly developed (Nb, Ti)_3Sn wires with Cu-Al_2O_3 reinforcing stabilizer. The coil weight is outstandingly reduced by as much as 70 %

NMR Study on La and Tl-based High-T_c Cuprates (High Field Superconductors)

NMR study on three types of high-T_C cuprates TlBa_2CaCu_2O_ (Tl1212), La_Ba_xCuO_4 (LBCO) and (La_Y_y)_Ce_xCuO_4 (LYCCO) is reported. First the Knight shift in the superconducting state was investigated for the Zn-substituted TlBa_2Ca(Cu_Zn_z)_2O_, which belongs to the over-doped region. The temperature dependence of the Knight shift was successfully explained in terms of the partially closed d-wave model proposed by Kitaoka et al. The reduction in T_C by Zn-substitution was also consistent with Miyake\u27s theoretical calculation on the potential scattering of the unitarity limit in the d-wave superconductors. Next, the impurity effect on the anomalous suppression of the superconductivity in La_Ba_xCuO_4 (LBCO) around x≅1/8 was investigated by La-NMR and ultrasonic measurements. The transition temperatures of the magnetic order and of the structural phase transformation in Zn^ and Ce^-doped LBCO have shown that the main and direct force to the suppression in the superconductivity is the magnetic ordering, and that the role of the structural phase transformation is the enhancement of the suppression. Lastly, the new electron doped cuprate free from 4f-spins has been synthesized and studied by NMR. Observed spectra of ^Cu without quadrupolar splitting similar to other conventional electron-doped cuprates indicate that the doped carrier in this system is electron like

Anomalous broadening of the spin-flop transition in the reentrant spin-glass phase of La2−x_{2-x}Srx_xCuO4_4 (x=0.018x=0.018)

The magnetization in a lightly doped La$_{2-x}$Sr$_x$CuO$_4$ ($x=0.018$) single crystal was measured. Spin-flop transition was clearly observed in the hole doped antiferromagnetically ordered state under increasing magnetic fields perpendicular to the CuO$_2$ plane. In the spin-glass phase below 25K, the spin-flop transition becomes broad but the step in the magnetization curve associated with the transition remains finite at the lowest temperature. We show in this report that, at low temperature, the homogeneous antiferromagnetic order is disturbed by the re-distribution of holes, and that the spatial variance of the local hole concentration around $x=0.018$ increases.Comment: to be published to Physical Review

Superconducting Gap Structure of Spin-Triplet Superconductor Sr_2RuO_4 Studied by Thermal Conductivity

To clarify the superconducting gap structure of the spin-triplet superconductor Sr_2RuO_4, the in-plane thermal conductivity has been measured as a function of relative orientations of the thermal flow, the crystal axes, and a magnetic field rotating within the 2D RuO_2 planes. The in-plane variation of the thermal conductivity is incompatible with any model with line nodes vertical to the 2D planes and indicates the existence of horizontal nodes. These results place strong constraints on models that attempt to explain the mechanism of the triplet superconductivity.Comment: 5 pages, 4 figures, to be published in Phys. Rev. Let

Molecular basis for bacterial peptidoglycan recognition by LysM domains.

Carbohydrate recognition is essential for growth, cell adhesion and signalling in all living organisms. A highly conserved carbohydrate binding module, LysM, is found in proteins from viruses, bacteria, fungi, plants and mammals. LysM modules recognize polysaccharides containing N-acetylglucosamine (GlcNAc) residues including peptidoglycan, an essential component of the bacterial cell wall. However, the molecular mechanism underpinning LysM-peptidoglycan interactions remains unclear. Here we describe the molecular basis for peptidoglycan recognition by a multimodular LysM domain from AtlA, an autolysin involved in cell division in the opportunistic bacterial pathogen Enterococcus faecalis. We explore the contribution of individual modules to the binding, identify the peptidoglycan motif recognized, determine the structures of free and bound modules and reveal the residues involved in binding. Our results suggest that peptide stems modulate LysM binding to peptidoglycan. Using these results, we reveal how the LysM module recognizes the GlcNAc-X-GlcNAc motif present in polysaccharides across kingdoms

Water-Cooled Magnet for a 40T Compact Hybrid Magnet(Magnet Technology)

A water-cooled poly Bitter magnet for a new compact hybrid magnet was designed under the fully utilization of the electric power source of 8 MW and the cooling systems installed in the High Field Laboratory for Superconducting Materials, Tohoku University. Supposing copper-silver plates with high yield strength are used, a poly Bitter magnet can be designed. The magnet consists of four axial water-cooled Bitter coils which are electrically connected in series and all of cooling water flows from the bottom tc upper side of coils. The designed poly Bitter magnet will produce 24 T in the room temperature bore of 14 mm and can provide 40 T as a hybrid magnet with backup field of 16 T by the combined superconducting magne