Tungsten ditelluride has attracted intense research interest due to the recent discovery of its large unsaturated magnetoresistance up to 60 T. Motivated by the presence of a small, sensitive Fermi surface of 5d electronic orbitals, we boost the electronic properties by applying a high pressure, and introduce superconductivity successfully. Superconductivity sharply appears at a pressure of 2.5 GPa, rapidly reaching a maximum critical temperature (Tc) of 7 K at around 16.8 GPa, followed by a monotonic decrease in Tc with increasing pressure, thereby exhibiting the typical dome-shaped superconducting phase. From theoretical calculations, we interpret the low-pressure region of the superconducting dome to an enrichment of the density of states at the Fermi level and attribute the high-pressure decrease in Tc to possible structural instability. Thus, tungsten ditelluride may provide a new platform for our understanding of superconductivity phenomena in transition metal dichalcogenides.

As a new type of topological materials, ZrTe 5 shows many exotic properties under extreme conditions. Using resistance and ac magnetic susceptibility measurements under high pressure, while the resistance anomaly near 128 K is completely suppressed at 6.2 GPa, a fully superconducting transition emerges. The superconducting transition temperature T c increases with applied pressure, and reaches a maximum of 4.0 K at 14.6 GPa, followed by a slight drop but remaining almost constant value up to 68.5 GPa. At pressures above 21.2 GPa, a second superconducting phase with the maximum T c of about 6.0 K appears and coexists with the original one to the maximum pressure studied in this work. In situ high-pressure synchrotron X-ray diffraction and Raman spectroscopy combined with theoretical calculations indicate the observed two-stage superconducting behavior is correlated to the structural phase transition from ambient Cmcm phase to high-pressure C2/m phase around 6 GPa, and to a mixture of two high-pressure phases of C2/m and P-1 above 20 GPa. The combination of structure, transport measurement, and theoretical calculations enable a complete understanding of the emerging exotic properties in 3D topological materials under extreme environments.high pressure | Dirac semimetals | superconductivity | synchrotron X-ray diffraction S ince the first report of topological insulator, an extensive attention in recent years has been focused on newly emergent Dirac materials including topological insulators (1-3), Dirac semimetals (4, 5), and Weyl semimetals (5-7) for their unique quantum phenomena. ZrTe 5 has been studied for a long time due to its large thermoelectric power (8, 9), resistivity anomaly (10, 11), and large positive magnetoresistance (12). Recent theoretical works (13,14) have proposed that single-layer ZrTe 5 is a large gap quantum spin hall insulator, but the bulk ZrTe 5 behaves between the strong and weak topological insulator. These predictions spark the renewed interest in the investigation of its Dirac and topological characters. Indeed, the magnetotransport experiments (15) have observed the chiral magnetic effect, both angle-resolved photoemission spectroscopy (15) and magneto-infrared spectroscopy (16, 17) study show the electronic structure of ZrTe 5 is similar with other three-dimensional (3D) Dirac semimetals like Na 3 Bi (18-20) and Cd 3 As 2 (21-25). These results suggest that ZrTe 5 is a very promising system that hosts topological properties and might help to pave a new way for further experimental studies of topological phase transitions.As one of the fundamental state parameters, high pressure is an effective, clean way to tune lattice as well as electronic states, especially in quantum states (26)(27)(28). In this work, by performing resistance and ac magnetic susceptibility measurements on ZrTe 5 single crystal at various pressures up to 68.5 GPa, a superconducting transition at 1.8 K was first noticed at a pressure of 6.2 GPa. It was interesting to notice that the occurrence of the metallic pha...

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ClinicalTrials.gov: NCT02479581.

BackgroundLung cancer remains the top contributor to cancer-related mortality worldwide. Long non-coding RNAs (lncRNAs) have been reported to participate in normal development and tumorigenesis. LncRNA nuclear enriched abundant transcript 1 (NEAT1) is highly expressed in lung cancer and promotes lung cancer cell proliferation and migration. However, the upstream regulatory mechanism still needs investigation.MethodsIn the present study, we investigated the upstream regulators and mechanisms of NEAT1 expression disorders. We first examined NEAT1 expression in lung adenocarcinoma tissues and its correlation with clinic features in patient with lung adenocarcinoma; next, the detailed function of NEAT1 in lung cancer cell proliferation and migration was assessed. To investigate whether NF-κB acts as a transcription factor of NEAT1 to activate its expression, we validated the combination between NF-κB and NEAT1, and NF-κB regulation of NEAT1 upon LPS stimulation. Further, the effect of NF-κB upstream regulator, TLR4, on NEAT1 expression upon LPS stimulation was examined. Galectin-3 reportedly serves as a ligand of TLR4 and promotes TLR4, MyD88 and p-p65 expression; we investigated whether Galectin-3 could modulate lung adenocarcinoma cell proliferation and migration through TLR4/NF-κB/NEAT1. Finally, the expression and correlation of the above factors in lung adenocarcinoma tissues was validated.ResultsNEAT1 is highly expressed in lung adenocarcinoma tissues and promotes lung cancer cell proliferation and migration. NF-κB binds to NEAT1 promoter to activate NEAT1 expression after LPS-stimulated p65 nucleus translocation. LPS stimulation activates TLR4 signaling, followed by downstream NF-κB activation, and ultimately NEAT1 expression activation. Galectin-3 activates TLR4 signaling thus affecting lung cancer cell proliferation and migration through TLR4/NF-κB/NEAT1. Galectin-3 and TLR4 expression are abnormally up-regulated in lung adenocarcinoma tissues, and positively correlated with NEAT1 expression.ConclusionWe confirmed that Galectin-3 as a ligand of TLR4 induced TLR4 signaling activation in lung adenocarcinoma cells, thereby activating downstream p65 nucleus translocation, promoting NEAT1 expression, and finally affecting lung adenocarcinoma cell proliferation and migration. Inhibiting Galectin-3-induced TLR4 signaling activation, thus to reduce p65-activated NEAT1 expression might be a promising strategy of suppressing lung adenocarcinoma cell proliferation and migration.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4461-z) contains supplementary material, which is available to authorized users.

Among the family of transition metal dichalcogenides, ReS 2 occupies a special position, which crystalizes in a unique distorted lowsymmetry structure at ambient conditions. The interlayer interaction in ReS 2 is rather weak, thus its bulk properties are similar to those of monolayer. However, how compression changes its structure and electronic properties is unknown so far. Here using ab initio crystal structure searching techniques, we explore the high-pressure phase transitions of ReS 2 extensively and predict two new high-pressure phases. The ambient pressure phase transforms to a "distorted-1T" structure at very low pressure and then to a tetragonal I4 1 /amd structure at around 90 GPa. The "distorted-1T" structure undergoes a semiconductor-metal transition at around 70 GPa with a band overlap mechanism. Electron-phonon calculations suggest that the I4 1 /amd structure is superconducting and has a critical superconducting temperature of about 2 K at 100 GPa. We further perform high-pressure electrical resistance measurements up to 102 GPa. Our experiments confirm the semiconductor-metal transition and the superconducting phase transition of ReS 2 under high pressure. These experimental results are in good agreement with our theoretical predictions.

Due to fundamental interest and potential applications in quantum computation, tremendous efforts have been invested to study topological superconductivity. However, bulk topological superconductivity seems to be difficult to realize and its mechanism is still elusive. Several possible routes to induce topological superconductivity have been proposed, including proximity efforts, doping or pressurizing a topological insulator or semimetal. Among them, the pressurizing is considered to be a "clean" way to tune the electronic structures. Here we report the discovery of a pressure-induced topological and superconducting phase of SnSe, a material which is highly focused recently due to its superior thermoelectric properties. In situ highpressure electrical transport and synchrotron X-ray diffraction measurements show that the superconductivity emerges along with the formation of a CsCl-type structural symmetry of SnSe above around 27 GPa, with a maximum critical temperature of 3.2 K at 39 GPa. Based on ab initio calculations, this CsCl-type SnSe is predicted to be a Dirac line nodes (DLN) semimetal in the absence of spin-orbit coupling, whose DLN states are protected by the coexistence of timereversal and inversion symmetries. These results make CsCl-type SnSe an interesting model platform with simple crystal symmetry to study the interplay of topological physics and superconductivity.

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