Enhanced superconducting transition temperatures in the rocksalt-type superconductors In1-xSnxTe (x <= 0.5)

We investigate superconductivity in In1-xSnxTe (x <= 0.5) synthesized at high pressures of up to 2 GPa and observe an enhancement of the superconducting transition temperature T-c for increasing tin concentration x. These compounds have not been accessible in rocksalt structure via conventional ambient pressure synthesis. While the lattice constant smoothly increases with x, T-c saturates around x = 0.4. Electronic structure calculations indicate that the Tc modulation is brought on by the change of the density of states in the vicinity of the Fermi energy [N(E-F)]. However, differences between the calculated N(E-F) and the observed electronic specific-heat coefficient indicate that the phonon dispersion plays an important role in the system and that the mechanism of superconductivity may not be the same in the entire doping range

Cisplatin-induced programmed cell death ligand-2 expression is associated with metastasis ability in oral squamous cell carcinoma.

Programmed cell death ligands (PD-Ls) are expressed in tumor cells where they bind to programmed cell death-1, an immunocyte co-receptor, resulting in tumor cell evasion from the immune system. Chemotherapeutic drugs have been recently reported to induce the expression of PD-L, such as PD-L1, in some cancer cells. However, little is known regarding PD-L2 expression and its role in oral squamous cell carcinoma (OSCC). In this study, we examined the effect of cisplatin on the expression and regulation of PD-L2 in OSCC cell lines and analyzed malignant behavior in PD-L2-expressing cells using colony, transwell and transformation assays. In addition, we examined PD-L2 expression in the tumor tissues of OSCC patients using cytology and tissue microarray methods. In OSCC cell lines, cisplatin treatment upregulated PD-L2 expression, along with that of the drug efflux transporter ABCG2, via signal transducers and activator of transcription (STAT) 1/3 activation. Moreover, PD-L2-positive or PD-L2-overexpressing cells demonstrated upregulation in both invasion and transformation ability but not in proliferation compared with PD-L2-negative or PD-L2-silencing cells. PD-L2 expression was also observed in OSCC cells of cytology samples and tissue from OSCC patients. The intensity of PD-L2 expression was correlated with more malignant morphological features in the histological appearance and an invasive pattern. Our findings indicate that cisplatin-upregulated PD-L2 expression in OSCC via STAT1/3 activation and the expression of PD-L2 are likely to be associated with malignancy in OSCC. The PD-L2 expression in cisplatin-resistant OSCC cells may be a critical factor in prognosis of advanced OSCC patients.福岡歯科大学2019年

Electron-Deficient Contorted Polycyclic Aromatic Hydrocarbon via One-Pot Annulative π-Extension of Perylene Diimide

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Paramagnetic magnetostriction in the chiral magnet CrNb3S6 at room temperature

We report that the magnetostriction (MS) effects occur in a paramagnetic state of a chiral magnet CrNb3S6. Through a series of experimental tests at room temperature, structural changes were observed at the level of a unit cell. The structural parameters are dependent of the strength and direction of magnetic field (H) even at temperature excessively higher than the magnetic ordering temperature Tc of 127 K. The present paramagnetic MS prominently appeared under H∥ the ab plane (easy plane) as opposed to under H∥ the c axis. Features observed in the paramagnetic MS effect significantly differ from those of the spontaneous MS in the vicinity of Tc [Phys. Rev. B 102, 014446 (2020)]. In this material, the orbital angular momentum L of Cr originates from the hybridization between Cr and Nb, and L is strongly coupled with the crystal structure [Phys. Rev. B 99, 174439 (2019)]. The present study clarified that the symmetry of the CrS6 octahedron is sensitive to H even at room temperature. The paramagnetic spin-orbit coupling should induce the distortion of CrS6 octahedron, resulting in the changes in Cr-Nb(4f) distance via the change in the hybridization between Cr-a1g and Nb-4dz2 orbitals

Magnetostriction related to skyrmion-lattice formation in chiral magnet FeGe

The B20 type chiral magnet FeGe exhibits the formation of skyrmion-lattice (SkL) phases in the vicinity of the magnetic ordering temperature. The SkL is a magnetic superlattice composed of vortex-type topological spin objects, and it has experimentally been known that its formation requires the existence of an intermediate (IM) phase between SkL and the paramagnetic (PM) phases. We take interest in how the crystal lattice experiences the formation of these topological spin texture. In this study, we observed the so-called spin–orbit coupling induced magnetostriction related to these topological spin texture formation, in addition to the ac magnetization anomalies. The temperature and magnetic field dependences of the lattice parameter reflected the transformation of phases, such as helimagnetic (HM), SkL, IM, conical (CM), and PM phases. In the PM region, a phase characterized as gaseous skyrmions was detected similarly to the case of the same B20 type MnSi. Furthermore, the HM, CM, and IM phases were also divided into two regions. Thus, the precise phase diagram near Tc was reconstructed from the prospect of the magnetostriction such that we demonstrated that the stabilization of skyrmions needs a finite magnetic field.journal articl

Saturated Linkers in Two-Dimensional Covalent Organic Frameworks Boost Their Luminescence

The development of highly luminescent two-dimensional covalent organic frameworks (COFs) for sensing applications remains challenging. To suppress commonly observed photoluminescence quenching of COFs, we propose a strategy involving interrupting the intralayer conjugation and interlayer interactions using cyclohexane as the linker unit. By variation of the building block structures, imine-bonded COFs with various topologies and porosities are obtained. Experimental and theoretical analyses of these COFs disclose high crystallinity and large interlayer distances, demonstrating enhanced emission with record-high photoluminescence quantum yields of up to 57% in the solid state. The resulting cyclohexane-linked COF also exhibits excellent sensing performance for the trace recognition of Fe3+ ions, explosive and toxic picric acid, and phenyl glyoxylic acid as metabolites. These findings inspire a facile and general strategy to develop highly emissive imine-bonded COFs for detecting various molecules.journal articl