Mechanisms by which blood cells sense shear stress are poorly characterized. In platelets, glycoprotein (GP)Ib–IX receptor complex has been long suggested to be a shear sensor and receptor. Recently, a relatively unstable and mechanosensitive domain in the GPIbα subunit of GPIb–IX was identified. Here we show that binding of its ligand, von Willebrand factor, under physiological shear stress induces unfolding of this mechanosensory domain (MSD) on the platelet surface. The unfolded MSD, particularly the juxtamembrane ‘Trigger' sequence therein, leads to intracellular signalling and rapid platelet clearance. These results illustrate the initial molecular event underlying platelet shear sensing and provide a mechanism linking GPIb–IX to platelet clearance. Our results have implications on the mechanism of platelet activation, and on the pathophysiology of von Willebrand disease and related thrombocytopenic disorders. The mechanosensation via receptor unfolding may be applicable for many other cell adhesion receptors.
Key Points
Pulling of VWF A1 domain that is engaged to GPIb-IX induces unfolding of a hitherto unidentified mechanosensitive domain in GPIbα. The spatial proximity of the mechanosensitive domain to GPIbβ and GPIX suggests a novel mechanism of platelet mechanosensing.
2D transition metal dichalcogenides are promising candidates for high‐performance photodetectors. However, the relatively low response speed as well as the complex transfer process hinders their wide applications. Herein, for the first time, the fabrication of a few‐layer MoTe2/Si 2D–3D vertical heterojunction for high‐speed and broadband photodiodes by a pulsed laser deposition technique is reported. Owing to the high junction quality, ultrathin MoTe2 film thickness, and unique vertical n–n heterojunction structure, the photodiode exhibits excellent device performance in terms of a high responsivity of 0.19 A W−1 and a large detectivity of 6.8 × 1013 Jones. The device is also capable of detecting a broadband light with wavelength spanning from 300 to 1800 nm. More importantly, the device possesses an ultrahigh response speed up to 150 ns with a 3‐dB electrical bandwidth approaching 0.12 GHz. This work paves the way toward the fabrication of novel 2D–3D heterojunctions for high‐performance, ultrafast photodetectors.
Atomically dispersed FeN 4 catalysts have been considered as potential materials to replace Pt-based catalysts for the oxygen reduction reaction (ORR), but they often suffer from sluggish O 2 activation kinetics due to the symmetrical charge distribution. Herein, we introduce external N, including pyrrolic-N (PN) and graphitic-N (GN), as an electron acceptor near FeN 4 to regulate its charge distribution and improve its ORR activity. Theoretical calculations reveal that introduction of PN evokes much enhanced electron redistribution and local electrical field on the Fe site compared with those observed with GN introduction and the pristine one. Synchrotron X-ray absorption spectroscopy and X-ray photoelectron spectroscopy validate the positive charge accumulation of Fe in the FeN 4 site induced by introducing PN. Thus, the obtained FeN 4 -PN exhibits a great performance for ORR in 0.1 M KOH with a remarkable half-wave potential of 0.91 V versus reversible hydrogen electrode, as well as a Tafel slope of 58 mV decade −1 . This work provides a guide to improve the catalytic performances of single-atom catalysts by introducing chargeredistribution sites.
Electrolysis of water is regarded as an attractive and feasible way for producing hydrogen. So far, various non‐noble metal nanomaterials have been reported as excellent electrocatalysts for hydrogen evolution reaction. Especially, due to the low cost, earth‐abundance and tunable properties, transition metal selenides with different compositions, sizes and structures have been explored broadly as efficient catalysts with the relatively high activities, high stabilities and high efficiencies in full pH range of electrolyte for electrochemical hydrogen evolution reaction. Thus, in this Minireview, after introducing several commonly used electrochemical terms about hydrogen evolution reaction, we mainly focus on various kinds of the transition metal selenides that have been documented as electrocatalysts for hydrogen evolution reaction. Particularly, the merits and demerits of transition metal selenides for hydrogen evolution reaction are systematically discussed. Moreover, we also analyze the encountered challenges and present an outlook for the rapid development of transition metal selenides. We hope this Minireview can bring some fundamental understanding for the readers interested in the transition metal selenides and hydrogen evolution reaction.
Adipic acid is an important building block of polymers, and is commercially produced by thermo-catalytic oxidation of ketone-alcohol oil (a mixture of cyclohexanol and cyclohexanone). However, this process heavily relies on the use of corrosive nitric acid while releases nitrous oxide as a potent greenhouse gas. Herein, we report an electrocatalytic strategy for the oxidation of cyclohexanone to adipic acid coupled with H2 production over a nickel hydroxide (Ni(OH)2) catalyst modified with sodium dodecyl sulfonate (SDS). The intercalated SDS facilitates the enrichment of immiscible cyclohexanone in aqueous medium, thus achieving 3.6-fold greater productivity of adipic acid and higher faradaic efficiency (FE) compared with pure Ni(OH)2 (93% versus 56%). This strategy is demonstrated effective for a variety of immiscible aldehydes and ketones in aqueous solution. Furthermore, we design a realistic two-electrode flow electrolyzer for electrooxidation of cyclohexanone coupling with H2 production, attaining adipic acid productivity of 4.7 mmol coupled with H2 productivity of 8.0 L at 0.8 A (corresponding to 30 mA cm−2) in 24 h.
Electrochemical reduction of CO2 provides an ideal approach to convert the greenhouse gas into fuels under mild conditions. Copper electrodes are capable of producing significant amounts of hydrocarbons, but the selectivity to convert CO2 into methane (CH4) remains low. Here, we prepared functionalized Cu nanowire electrodes by coating polymers (polydopamine, PDA) and experimentally verified that the functionalized CuNWs indeed shows 2.3 times higher CH4 selectivity compared with that of CuNWs. The PDA functionalized CuNWs catalyst remains catalytically stable for in excess of 14 hours. We experimentally reveal that the amino groups could be responsible for the capture and delivery of protons for the hydronation of CO* intermediates and phenolic hydroxyl groups for the stabilization of CO* intermediates. The results provide us insights into a new approach to optimize the electrochemical methanation of CO2 by polymers that contain abundant functional groups.
A gate-tunable hybrid-dimensional heterojunction is reported for emulating Boolean logics and dendritic integrations by combining electric and photonic stimuli.
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