Molybdenum disulfide (MoS2) is systematically studied using Raman spectroscopy with ultraviolet and visible laser lines. It is shown that only the Raman frequencies of $ E_{2{\rm g}}^1 $ and $ A_{{\rm 1g}}^{} $ peaks vary monotonously with the layer number of ultrathin MoS2 flakes, while intensities or widths of the peaks vary arbitrarily. The coupling between electronic transitions and phonons are found to become weaker when the layer number of MoS2 decreases, attributed to the increased electronic transition energies or elongated intralayer atomic bonds in ultrathin MoS2. The asymmetric Raman peak at 454 cm−1, which has been regarded as the overtone of longitudinal optical M phonons in bulk MoS2, is actually a combinational band involving a longitudinal acoustic mode (LA(M)) and an optical mode ($ A_{{\rm 2u}}^{} $). Our findings suggest a clear evolution of the coupling between electronic transition and phonon when MoS2 is scaled down from three‐ to two‐dimensional geometry.

Intracellular lipopolysaccharide from Gram-negative bacteria including Escherichia coli, Salmonella typhimurium, Shigella flexneri, and Burkholderia thailandensis activates mouse caspase-11, causing pyroptotic cell death, interleukin-1β processing, and lethal septic shock. How caspase-11 executes these downstream signalling events is largely unknown. Here we show that gasdermin D is essential for caspase-11-dependent pyroptosis and interleukin-1β maturation. A forward genetic screen with ethyl-N-nitrosourea-mutagenized mice links Gsdmd to the intracellular lipopolysaccharide response. Macrophages from Gsdmd(-/-) mice generated by gene targeting also exhibit defective pyroptosis and interleukin-1β secretion induced by cytoplasmic lipopolysaccharide or Gram-negative bacteria. In addition, Gsdmd(-/-) mice are protected from a lethal dose of lipopolysaccharide. Mechanistically, caspase-11 cleaves gasdermin D, and the resulting amino-terminal fragment promotes both pyroptosis and NLRP3-dependent activation of caspase-1 in a cell-intrinsic manner. Our data identify gasdermin D as a critical target of caspase-11 and a key mediator of the host response against Gram-negative bacteria.

A new phototransistor based on the mechanically exfoliated single-layer MoS(2) nanosheet is fabricated, and its light-induced electric properties are investigated in detail. Photocurrent generated from the phototransistor is solely determined by the illuminated optical power at a constant drain or gate voltage. The switching behavior of photocurrent generation and annihilation can be completely finished within ca. 50 ms, and it shows good stability. Especially, the single-layer MoS(2) phototransistor exhibits a better photoresponsivity as compared with the graphene-based device. The unique characteristics of incident-light control, prompt photoswitching, and good photoresponsivity from the MoS(2) phototransistor pave an avenue to develop the single-layer semiconducting materials for multifunctional optoelectronic device applications in the future.

A long-term, consistent, high-resolution climate dataset for the North American domain, as a major improvement upon the earlier global reanalysis datasets in both resolution and accuracy, is presented.

As a promising non-precious catalyst for the hydrogen evolution reaction (HER; refs ,,,,), molybdenum disulphide (MoS2) is known to contain active edge sites and an inert basal plane. Activating the MoS2 basal plane could further enhance its HER activity but is not often a strategy for doing so. Herein, we report the first activation and optimization of the basal plane of monolayer 2H-MoS2 for HER by introducing sulphur (S) vacancies and strain. Our theoretical and experimental results show that the S-vacancies are new catalytic sites in the basal plane, where gap states around the Fermi level allow hydrogen to bind directly to exposed Mo atoms. The hydrogen adsorption free energy (ΔGH) can be further manipulated by straining the surface with S-vacancies, which fine-tunes the catalytic activity. Proper combinations of S-vacancy and strain yield the optimal ΔGH = 0 eV, which allows us to achieve the highest intrinsic HER activity among molybdenum-sulphide-based catalysts.