Porous bowl-shaped VS 2 nanosheets/graphene composite for high-rate lithium-ion storage

Two-dimensional (2D) layered vanadium disulfide (VS2) is a promising anode material for lithium ion batteries (LIBs) due to the high theoretical capacity. However, it remains a challenge to synthesize monodispersed ultrathin VS2 nanosheets to realize the full potential. Herein, a novel solvothermal method has been developed to prepare the monodispersed bowl-shaped NH3-inserted VS2 nanosheets (VS2). The formation of such a unique structure is caused by the blocked growth of (001) or (002) crystal planes in combination with a ripening process driven by the thermodynamics. The annealing treatment in Ar/H2 creates porous monodispersed VS2 (H-VS2), which is subsequently integrated with graphene oxide to form porous monodispersed H-VS2/rGO composite coupled with a reduction process. As an anode material for LIBs, H-VS2/rGO delivers superior rate performance and longer cycle stability: a high average capacity of 868/525 mAh g−1 at a current density of 1/10 A g−1; a reversible capacity of 1177/889 mAh g−1 after 150/500 cycles at 0.2/1 A g−1. Such excellent electrochemical performance may be attributed to the increased active sites available for lithium storage, the alleviated volume variations and the shortened Li-ion diffusion induced from the porous structure with large specific surface area, as well as the protective effect from graphene nanosheets

Low-Threshold Nanowire Laser Based on Composition-Symmetric Semiconductor Nanowires

Low-threshold nanoscale lasers are attractive for their promising applications in highly integrated photonic devices and systems. Here we report the controllable growth of composition-symmetric CdS_<i>x</i>Se_1–<i>x</i> nanowires by using a multistep thermal evaporation route with moving sources. Microstructure analyses reveal the obtained wires are high-quality single crystals with the composition gradually changed from the center toward their both ends. Under laser illumination, these wires exhibit symmetrical color distribution along the length direction, with red at the center and green at the both ends. Optically pumped lasing is realized at room temperature using these composition-symmetric nanowires, with the threshold several times lower than that of composition-homogeneous wires. This new nanowire structure will have potential applications as low-threshold nanoscale lasers in integrated nanophotonics

Spike substitution T813S increases Sarbecovirus fusogenicity by enhancing the usage of TMPRSS2.

SARS-CoV Spike (S) protein shares considerable homology with SARS-CoV-2 S, especially in the conserved S2 subunit (S2). S protein mediates coronavirus receptor binding and membrane fusion, and the latter activity can greatly influence coronavirus infection. We observed that SARS-CoV S is less effective in inducing membrane fusion compared with SARS-CoV-2 S. We identify that S813T mutation is sufficient in S2 interfering with the cleavage of SARS-CoV-2 S by TMPRSS2, reducing spike fusogenicity and pseudoparticle entry. Conversely, the mutation of T813S in SARS-CoV S increased fusion ability and viral replication. Our data suggested that residue 813 in the S was critical for the proteolytic activation, and the change from threonine to serine at 813 position might be an evolutionary feature adopted by SARS-2-related viruses. This finding deepened the understanding of Spike fusogenicity and could provide a new perspective for exploring Sarbecovirus' evolution