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Abstract Bulk Ge-Sn chemical compounds have rarely been synthesized at ambient pressure, due to the low solubility of Sn in Ge. Atomic and electronic structures can be significantly changed by pressure, which holds the promise to synthesize bulk Sn-Ge compounds. Here, we identify the formation of three stoichiometric Ge-Sn compounds (Ge 2 Sn, Ge 3 Sn 2 and Ge 2 Sn 3) under high pressure, using the CALYPSO structure prediction method in combination with first-principles calculations. The concentration of Sn (60%) in Ge 2 Sn 3 is higher than that of any synthesized Ge-Sn known compounds. With an increasing Sn concentration, the Ge Ge bonding patterns of Ge-Sn compounds evolve from infinite 2D-nets (Ge 2 Sn) in turn to rings (Ge 3 Sn 2) and then tetramers (Ge 2 Sn 3). The calculated electronic band structures show that all the predicted phases are metallic. Our results will pave way for further understanding of the Ge-Sn phase diagram. Highlights • The concentration of Sn in proposed Ge 2 Sn 3 is higher than that of any synthesized Ge-Sn known compounds. • Unlike the earlier work, the proposed Ge-Sn compounds are all metallic. • With the increasing Sn concentration, intriguing Ge−Ge bonding features are identified in the Ge-Sn compounds. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the high pressure phases of CdF2 by a joint theoretical and experimental study. The structural and electronic properties of CdF2 were extensively explored to high pressure by ab initio calculations based on the density functional theory. A structural phase transition from the fluorite-type (Fm-3m, ) structure to the cotunnite-type (Pnma, ) structure was estimated below 8 GPa, and this phase transition was examined by the high pressure experiments up to 35 GPa at room temperature. Both high pressure angle dispersive X-ray diffraction and Raman spectroscopy experiments provided convincing evidence to verify the phase transition. Our work makes clear pressure-induced phase transitions and structural information of CdF2 under high pressure. [Copyright &y& Elsevier]

There are lots of efforts on the investigate for high-temperature superconductors in hydrogen-rich system, since the LaH 10 (250–260 K) and SH 3 (203 K) compounds smashed the record for superconducting temperatures above 200 K. In this study, as a result of extensive simulations, we propose several unreported thorium hydrides under pressures, using our in-house developed CALYPSO structure searching method in combination with density functional theory. New ThH 3 and Th 2 H 7 structures are found as thermodynamically stable phases at atmospheric pressure. As a result of the analysis of the electronic properties in those predicted structures, it is found that the f electrons of Th and the s electrons of H mainly contribute to the fermi level, thus leading to the superconductivity. Our results enrich the knowledge in the Th–H system and provide insights into designing superconducting hydrides under high pressure. • New ThH 3 and Th 2 H 7 structures are predicted at atmospheric pressure. • The f electrons of Th and the s electrons of H mainly dominated the superconductivity. • Our results provide insights into designing superconducting hydrides under high pressure. [ABSTRACT FROM AUTHOR]

Summary In eastern China, live poultry markets were successively re-opened in the summer of 2013 following their closure in April 2013. We detected influenza A/H7N9 RNA with positive rates from 4% to 22.2% among poultry samples in targeted markets in Huzhou City, China, from August 6 to September 24, 2013. Phylogenetic analyses of hemagglutinin and neuraminidase genes confirmed that the strain prevalent among poultry in Huzhou City in the summer of 2013 belonged to the same genotype as those capable of infecting humans. These results raise concern for a further outbreak of H7N9 in the cooler season. [ABSTRACT FROM AUTHOR]

Most patients infected with avian H7N9 influenza virus develop severe disease, including respiratory failure, acute respiratory distress syndrome (ARDS), and multi-organ failure. The pathogenesis of H7N9 infection is not fully understood. This study revealed that H7N9-infected patients who had fatal outcomes or critical illness all had pre-existing chronic diseases. The patients did not have obvious systemic inflammation compared to the healthy controls. However, their fatal outcomes and critically severe illness were significantly associated with high serum levels of tumor necrosis factor (TNF)-α. Interestingly, the degree of liver damage in these patients significantly correlated with their serum levels of Th2 cytokines, interleukin (IL)-4, and IL-9. Taken together, our results suggest that Th2-type inflammation in H7N9-infected patients with pre-existing chronic diseases likely contributes to the pathogenesis of H7N9 infection and is linked to poor clinical outcomes. [ABSTRACT FROM AUTHOR]

• Two new bulk structures of graphite-like layered K-BC 2 N are established. • K donates electrons to BC 2 N and increases the density of state at Fermi level. • K-BC 2 N is expected as a superconductor with critical temperature of 5-6 K. Ternary B-C-N materials have been widely investigated during recent decades. Additionally, previous investigations have indicated that intercalation of alkali metal could induce superconductivity emerged in layer structure. Motivated by this strategy, we attempt to establish the bulk structure of K-BC 2 N and explore its related properties by using density functional theory calculations. Two stable phases of K-BC 2 N were identified with anticipated metallic feature. Therefore, we calculated electron-phonon coupling interaction of K-BC 2 N within Allen-Dynes modified McMillan equation. The results confirm that bulk K-BC 2 N is a phonon-mediated superconductor with estimated critical temperature of 3 ∼ 6 K, providing a feasible approach for design and synthesis new superconductor at atmospheric pressure. [ABSTRACT FROM AUTHOR]

The stabilities and phase evolutions of the binary Bi–S compounds are investigated by using synchrotron radiation X-ray diffraction in a diamond anvil cell in combination with laser heating technique. When it is heated to 1300 K at 32.6 GPa, Bi 2 S 3 decomposes into element S and a new BiS phase, which can be quenched to ambient conditions. The present results verify that cubic BiS, with an unprecedented stoichiometry and novel bonding characteristics, is at least metastable. It may shed new light on the fundamental sciences and potential technologies of the group V-VI binary compounds. • The stabilities and phase evolutions of the binary Bi-S compounds under extreme conditions are investigated in detail. • Advanced synchrotron radiation X-ray diffraction in combination with laser heating technique is used. • Bi 2 S 3 is thermodynamically unstable and decompose into a novel phase with an unprecedented BiS stoichiometry. • The present results verify that cubic BiS, with an unprecedented stoichiometry, is at least metastable. [ABSTRACT FROM AUTHOR]