Recently, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants (B.1.1.7 and B.1351) have emerged harbouring mutations that make them highly contagious. The N501Y mutation within the ...receptor‐binding domain (RBD) of the spike protein of these SARS‐CoV‐2 variants may enhance binding to the human angiotensin‐converting enzyme 2 (hACE2). However, no molecular explanation for such an enhanced affinity has so far been provided. Here, using all‐atom molecular dynamics simulations, we show that Y501 in the mutated RBD can be well‐coordinated by Y41 and K353 in hACE2 through hydrophobic interactions, which may increase the overall binding affinity of the RBD for hACE2 by approximately 0.81 kcal·mol−1. The binding dynamics revealed in our study may provide a working model to facilitate the design of more effective antibodies.
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Currently, the new coronavirus disease 2019 (COVID-19) is a global pandemic without any well-calibrated treatment. To inactivate the SARS-CoV-2 virus that causes COVID-19, the main protease (Mpro) ...that performs key biological functions in the virus has been the focus of extensive studies. With the fast-response experimental efforts, the crystal structures of Mpro of the SARS-CoV-2 virus have just become available recently. Herein, we theoretically investigated the mechanism of binding between the Mpro’s pocket and various marketed drug molecules being tested in clinics to fight COVID-19 that show promising outcomes. By combining the existing experimental results with our computational ones, we revealed an important ligand binding mechanism of the Mpro, demonstrating that the binding stability of a ligand inside the Mpro pocket can be significantly improved if part of the ligand occupies its so-called “anchor” site. Along with the highly potent drugs and/or molecules (such as nelfinavir) revealed in this study, the newly discovered binding mechanism paves the way for further optimizations and designs of Mpro’s inhibitors with a high binding affinity.
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•Self-healing coating was prepared by adding microcapsules into an epoxy coating.•Intact self-healing coating exhibits excellent barrier property as epoxy coating.•Intact self-healing ...coating has higher water-uptake than intact epoxy coating.•Scratched self-healing coating has excellent healing and anticorrosion ability.•The failure reason of scratched self-healing coating was proposed and discussed.
In this study, a linseed oil encapsulated self-healing coating was developed by incorporating 10 wt% synthesized microcapsules into an epoxy-polyamine coating matrix. The linseed oil encapsulated polyurea-formaldehyde (PUF) microcapsules had ∼80 wt% core content with ∼80 um diameter. The influence of embedded microcapsules on the anticorrosive property of the self-healing coating had been studied by electrochemical impedance spectroscopy. The intact self-healing coating exhibited excellent anticorrosive property as the intact pure epoxy coating, although the addition of microcapsules into the epoxy matrix resulted in a higher water-uptake. The scratched self-healing coating showed excellent healing ability and corrosion inhibition function for microcracks, but it still cannot recover the barrier property as good as the intact coating. The failure of the scratched self-healing coating had been analyzed and the possible reason may be the formation of conductive pathways at the interface between the linseed oil film and the epoxy matrix and/or PUF microcapsule shell.
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As the black cesium lead iodide (CsPbI
) tends to transit into a yellow δ-phase at ambient, it is imperative to develop a stabilized black phase for photovoltaic applications. Herein, we report a ...distorted black CsPbI
film by exploiting the synergistic effect of hydroiodic acid (HI) and phenylethylammonium iodide (PEAI) additives. It is found that the HI induces formation of hydrogen lead iodide (HPbI
), an intermediate to the distorted black phase with appropriate band gap of 1.69 eV; while PEAI provides nucleation for optimized crystallization. More importantly, it stabilizes the distorted black phase by hindering phase transition via its steric effects. Upon optimization, we have attained solar cell efficiency as high as 15.07%. Specifically, the bare cell without any encapsulation shows negligible efficiency loss after 300 h of light soaking. The device keeps 92% of its initial cell efficiency after being stored for 2 months under ambient conditions.
A Two-Terminal Active Capacitor Wang, Haoran; Wang, Huai
IEEE transactions on power electronics,
2017-Aug., 2017-8-00, 20170801, Volume:
32, Issue:
8
Journal Article
Peer reviewed
This letter proposes a concept of two-terminal active capacitor implemented by power semiconductor switches and passive elements. The active capacitor has the same level of convenience as a passive ...one with two power terminals only. It is application independent and can be specified by rated voltage, ripple current, equivalent series resistance, and operational frequency range. The concept, control method, self-power scheme, and impedance characteristics of the active capacitor are presented. A case study of the proposed active capacitor for a capacitive dc-link application is discussed. The results reveal a significantly lower overall energy storage of passive elements and a reduced cost to fulfill a specific reliability target, compared to a passive capacitor solution. Proof-of-concept experimental results are given to verify the functionality of the proposed capacitor.
Crack detection on dam surfaces is an important task for safe inspection of hydropower stations. More and more object detection methods based on deep learning are being applied to crack detection. ...However, most of the methods can only achieve the classification and rough location of cracks. Pixel-level crack detection can provide more intuitive and accurate detection results for dam health assessment. To realize pixel-level crack detection, a method of crack detection on dam surface (CDDS) using deep convolution network is proposed. First, we use an unmanned aerial vehicle (UAV) to collect dam surface images along a predetermined trajectory. Second, raw images are cropped. Then crack regions are manually labelled on cropped images to create the crack dataset, and the architecture of CDDS network is designed. Finally, the CDDS network is trained, validated and tested using the crack dataset. To validate the performance of the CDDS network, the predicted results are compared with ResNet152-based, SegNet, UNet and fully convolutional network (FCN). In terms of crack segmentation, the recall, precision, F-measure and IoU are 80.45%, 80.31%, 79.16%, and 66.76%. The results on test dataset show that the CDDS network has better performance for crack detection of dam surfaces.
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Hierarchical porous carbon materials with high surface areas and a localized graphitic structure were simply prepared from sucrose using nano-ZnO as a hard template, activation agent and ...graphitization catalyst simultaneously, which exhibit an outstanding high-rate performance and can endure an ultrafast scan rate of 20 V s
and ultrahigh current density of 1000 A g
.
We report interesting photomechanical behaviors of the dynamic molecular crystals of (E)‐2‐(2,4‐dichlorostyryl)benzodoxazole (BOACl24). The photosalient effect of the rod‐like crystal based on a ...metal‐free olefin driven by photodimerization is observed. Moreover, the needle‐like crystals of BOACl24 exhibit a reversible bending away from a UV light source. The nanofibers curl easily under UV irradiation in an organogel, in which the photo‐induced rolling of a small slice occurs. This suggests that the rapid release of the accumulated strain during photodimerization may lead to a photosalient effect, and the bending or curling happens when the strain is released slowly. Notably, 2+2 cycloaddition takes place between two different conformational isomers of BOACl24 on account of the rotation of the benzoxazole ring around the C−C bond in an excited state before photodimerization. Such topo‐photochemical reaction has not been reported elsewhere.
Rollin' and tumblin': The dynamic molecular crystals of (dichlorostyryl)benzoxazole BOACl24 exhibit photomechanical motion induced by topo‐photochemical dimerization. The reversible controllable bending of these needle‐like crystals away from the light source driven by 2+2 cycloaddition resulted from the slow release of the strain accumulated by the movement of the atoms during photodimerization.
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Previous observational studies have suggested a potential relationship between osteoarthritis (OA) and the risk of cardiovascular disease (CVD), with conflicting results. We aimed to provide a ...systematic and quantitative summary of the association between OA and the risk of CVD. We searched Medline and EMBASE to retrieve prospective and retrospective studies that reported risk estimates of the association between OA status and CVD risk. Pooled estimates were calculated by a random effects model. The search yielded 15 articles including a total of 358,944 participants, including 80,911 OA patients and 29,213 CVD patients. Overall, the risk of CVD was significantly increased by 24% (RR: 1.24, 95% CI: 1.12 to 1.37, P < 0.001) in patients with OA compared with the general population, with no significant publication bias. Furthermore, sensitivity analysis indicated that our results were robust and were not influenced by any one study. In conclusion, this meta-analysis provides strong evidence that OA is a significant risk factor for CVD.
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Two novel bio-based polyols were synthesized from cardanol via thiol-ene/thiol-epoxy dual click-reactions. Compared with the cardanol-based polyols synthesized by the thiol-ene reaction, the ...cardanol-based polyols synthesized by thiol-ene/thiol-epoxy dual reactions have a higher hydroxyl number due to the additional secondary hydroxyl group generated from the thiol-epoxy reaction. The synthesized polyols were formulated with hexamethylene diisocyanate (HDI) trimers to prepare cardanol-based thermosetting polyurethane (PU) films. Thorough thermal and mechanical characterizations of the prepared PU films were carried out to study the structure–property relationship. An UV-aging test was conducted to characterize the color retention of the cardanol-based PU films. The thermal stability of cardanol-based PU films was improved after converting the phenolic hydroxyl to aliphatic hydroxyl. With increasing the hydroxyl number of cardanol-based polyols, the cross-link density, glass transition temperature, elastic modulus, tensile strength, and hardness of cardanol-based PU films were all improved. The results of this work confirmed that the utilization of thiol-ene/thiol-epoxy dual click-reactions is an effective approach to synthesize cardanol-based polyols with a relatively high hydroxyl number. The significance of this work is believed to broaden the usage of cardanol in different PU formulations and applications.
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