Properties of amorphous ternary alloy films a-SixCyGez:H prepared by magnetron co-sputtering

Amorphous Si_xC_yGe_z:H (x+y+z=1; z∼0.1) have been deposited by reactive sputtering of Si–Ge composite target in argon–methane gas mixtures. The effects of the addition of Ge and the methane partial pressure P on the film properties were investigated. At high P, the addition of Ge could improve the reduction of the photoconductivity with increasing P observed in a-Si_xC_y:H (z=0).     

准一维链状半导体BiSeI低温物性研究

A^ⅤB^ⅥC^Ⅶ(A=Bi,Sb;B=S,Se;C=I,Br)体系是一类典型的准一维链状半导体材料.由于其特殊的晶格和能带结构,A^ⅤB^ⅥC^Ⅶ体系表现出丰富的物性,如:铁电、压电、热电和光电导特性等,在太阳能电池、光电探测器及超级电容器等领域有着广泛的应用前景,引起了人们广泛的研究兴趣.其中,SbSI在低温下伴随铁电自发极化会出现反常的负热膨胀现象.BiSeI与SbSI结构类似,低温下的物性值得进一步研究.本工作利用物理气相输运法制备了高质量的BiSeI单晶样品,并利用Raman光谱、电输运测量、XRD及光致发光谱(PL)对其低温下的电输运、振动及结构性质进行了系统的研究.随温度降低,PL光谱结果表明低温下能隙内出现激子能级.低温Raman及XRD结果表明测试温区(10～300 K)内其结构对称性无明显改变.然而随温度降低,晶格在200～300 K范围内发生明显的负热膨胀现象.类比于SbSI,我们将BiSeI中的负热膨胀现象归因于410 K发生的反铁电相变.此工...     

Searches for dark matter via charged Higgs pair production in the Inert Doublet Model at a γγ collider

The Inert Doublet Model (IDM) is one of the simplest extensions beyond the Standard Model (SM) with an extended scalar sector, which provides a scalar dark matter particle candidate. In this study, we investigated the double charged Higgs production at a \begin{document}$\gamma\gamma$\end{document} collider. By scanning the whole parameter space, we obtained the parameter points corresponding to the correct relic abundance of dark matter. After applying all theoretical and experimental constraints, the parameter space for the existence of dark matter was extremely restricted. We performed an analysis of the signal of \begin{document}$H^+H^-$\end{document} production in the IDM and the SM background, with the optimized selection conditions chosen for the kinematic variables to maximize the signal significance. Comparing the signal with the background, we obtained the parameter points that may be detected in future \begin{document}$\gamma\gamma$\end{document} collider experiments.     

Assembly of the Thiolated [Au1Ag22(S-Adm)12]3+ Superatom Complex into a Framework Material through Direct Linkage by SbF6− Anions

Building framework materials with desirable properties and enhanced functionalities with nanocluster/superatom complexes as building blocks remains a challenge in the field of nanomaterials. In this study, the chiral [Au₁Ag₂₂(S-Adm)₁₂]³⁺ nanocluster/superatom complex (SC, in which S-Adm=1-adamantanethiol) was employed as a building block to construct the three-dimensional (3D) superatom complex inorganic framework (SCIF) materials SCIF-1 and SCIF-2 through inorganic SbF₆⁻ linkers. SCIF-1 is racemic due to the assembly of two SC enantiomers in a single crystal. In SCIF-2, the SC enantiomers are packed in separate crystals, thus producing larger channels and a circularly polarized luminescence (CPL) response. These two 3D SCIF materials exhibit unique sensitive photoluminescence (PL) in protic solvents. Our study provides a new pathway for creating novel open-framework materials with superatom complexes and a foundation for the further development of 3D framework materials for sensing and other applications.     

Fragmentation Mechanism of White Phosphorus: A Theoretical Insight into Multiple Cleavage/Formation of P−P and P−C Bonds

Molecular-level understanding of metal-mediated white phosphorus (P₄) activation is meaningful but challenging because of its direct relevance to the conversion of P₄ into useful organophosphorus compounds as well as the complicated and unforeseeable cleavage process of P−P bonds. The related study, however, has still rarely been achieved to date. Here, a theoretical insight into the step-by-step process of three P−P bond cleavage/four P−C bond formation for [P₃+P₁]-fragmentation of P₄ mediated by lutetacyclopentadienes is reported. The unique charge-separated intermediate and the intermolecular cooperation between two lutetacyclopentadienes play a vital role in the subsequent P−P/P−C bond breaking/forming. It is found that, although the first P−C formation is involved in the assembly of the cyclo-P₃ [R₄C₄P₃]⁻ unit, the construction of the aromatic five-membered P₁ heterocycle [R₄C₄P]⁻ is completed prior to the cyclo-P₃ formation. The reaction mechanism has been carefully elucidated by analyses of the geometric structure, frontier molecular orbitals, bond index, and natural charge, which greatly broaden and enrich the general knowledge of the direct functionalization of P₄.     

E-pharmacophore-based screening of mGluR5 negative allosteric modulators for central nervous system disorder

Glutamate, a major neurotransmitter in the central nervous system of human, plays a crucial role in various neurological pathways by activating the ligand-gated ion channels such as mGluR and iGluR. Dysfunction of mGluR 5 can cause Alzheimer’s disease, Parkinson’s disease, epilepsy, depression, anxiety, etc. In the current study, we have developed the energetically optimized pharmacophore model to screen the eMolecules database having more than 6 million compounds with the help of reported cocrystal structure with 3-chloro-5-[6-(5-fluoropyridin-2 yl)pyrimidin-4-yl]benzonitrile (PDB ID: 5CGD). The obtained hits were docked into the allosteric site of the target and further validation of E-pharmacophore was done by enrichment calculations followed by the molecular dynamics simulations to analyze the specific amino acid interactions with the compound present in the allosteric site of the receptor.     

Design principles of lead-carbon additives toward better lead-carbon batteries

In the last 20 years, lead-acid battery has experienced a paradigm transition to lead-carbon batteries due to the huge demand for renewable energy storage and start-stop hybrid electric vehicles. Carbon additives show a positive effect for retarding the sulfation of Pb negative electrode toward the partial state of charge operation. Lead-carbon composite additive could synergistically solve the problem of sulfation while inhibiting parasitic hydrogen evolution reaction of carbon. The design principles of lead-carbon additives toward future lead-carbon batteries are discussed in this paper.