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The advancement of cost-effective and selective electrocatalyst towards CO 2 to CO conversion is crucial for renewable energy conversion and storage, thus to achieve carbon-neutral cycle in a sustainable manner. In this communication, we report that Cu 2 Sb decorated Cu nanowire arrays on Cu foil act as a highly active and selective electrocatalyst for CO 2 to CO conversion. In CO 2 -saturated 0.1 M KHCO 3 , it achieves a high Faraday efficiency (FE) of 86.5% for CO, at −0.90 V vs. reversible hydrogen electrode (RHE). The H 2 /CO ratio is tunable from 0.08:1 to 5.9:1 by adjusting the potential. It is worth noting that HCOO − product was totally suppressed on such catalyst, compared with Sb counterpart. The improving selectivity for CO could be attributed to the bimetallic effect and nanowire arrays structure.

Three highly pathogenic β-coronaviruses have crossed the animal-to-human species barrier in the past two decades: SARS-CoV, MERS-CoV and SARS-CoV-2. To evaluate the possibility of identifying antibodies with broad neutralizing activity, we isolated a monoclonal antibody, termed B6, that cross-reacts with eight β-coronavirus spike glycoproteins, including all five human-infecting β-coronaviruses. B6 broadly neutralizes entry of pseudotyped viruses from lineages A and C, but not from lineage B, and the latter includes SARS-CoV and SARS-CoV-2. Cryo-EM, X-ray crystallography and membrane fusion assays reveal that B6 binds to a conserved cryptic epitope located in the fusion machinery. The data indicate that antibody binding sterically interferes with the spike conformational changes leading to membrane fusion. Our data provide a structural framework explaining B6 cross-reactivity with β-coronaviruses from three lineages, along with a proof of concept for antibody-mediated broad coronavirus neutralization elicited through vaccination. This study unveils an unexpected target for next-generation structure-guided design of a pan-β-coronavirus vaccine. Structural characterization of B6, a monoclonal antibody that cross-reacts with eight β-coronavirus spike proteins from three viral lineages, reveals a conserved cryptic epitope that could serve as a target for structure-guided design of a pan-β-coronavirus vaccine.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virions are surrounded by a lipid bilayer from which spike (S) protein trimers protrude 1 . Heavily glycosylated S trimers bind to the angiotensin-converting enzyme 2 receptor and mediate entry of virions into target cells 2 – 6 . S exhibits extensive conformational flexibility: it modulates exposure of its receptor-binding site and subsequently undergoes complete structural rearrangement to drive fusion of viral and cellular membranes 2 , 7 , 8 . The structures and conformations of soluble, overexpressed, purified S proteins have been studied in detail using cryo-electron microscopy 2 , 7 , 9 – 12 , but the structure and distribution of S on the virion surface remain unknown. Here we applied cryo-electron microscopy and tomography to image intact SARS-CoV-2 virions and determine the high-resolution structure, conformational flexibility and distribution of S trimers in situ on the virion surface. These results reveal the conformations of S on the virion, and provide a basis from which to understand interactions between S and neutralizing antibodies during infection or vaccination. Cryo-electron microscopy and tomography studies reveal the structures, conformations and distributions of spike protein trimers on intact severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virions and provide a basis for understanding the interactions of the spike protein with neutralizing antibodies.

The tremendous pandemic potential of coronaviruses was demonstrated twice in the past few decades by two global outbreaks of deadly pneumonia. The coronavirus spike (S) glycoprotein initiates infection by promoting fusion of the viral and cellular membranes through conformational changes that remain largely uncharacterized. Here we report the cryoEM structure of a coronavirus S glycoprotein in the postfusion state, showing large-scale secondary, tertiary, and quaternary rearrangements compared with the prefusion trimer and rationalizing the free-energy landscape of this conformational machine. We also biochemically characterized the molecular events associated with refolding of the metastable prefusion S glycoprotein to the postfusion conformation using limited proteolysis, mass spectrometry, and single-particle EM. The observed similarity between postfusion coronavirus S and paramyxovirus F structures demonstrates that a conserved refolding trajectory mediates entry of these viruses and supports the evolutionary relatedness of their fusion subunits. Finally, our data provide a structural framework for understanding the mode of neutralization of antibodies targeting the fusion machinery and for engineering next-generation subunit vaccines or inhibitors against this medically important virus family.

A fast and facile approach was designed to fabricate carbonate (Ci)-modified NiFe layered double hydroxide (LDH) nanosheets array on carbon cloth (CC) by dielectric barrier discharge (DBD) microplasma. The whole synthetic process can be completed within 1 h at ambient temperature and pressure. The prepared NiFe LDH-Ci/CC emerges a superior catalytic activity for oxygen evolving reaction in alkaline media, which only demands an overpotential of 240 mV at 20 mA cm −2 with a high stability for at least 90 h, and shows an excellent turnover frequency value of 0.323 mol O 2  s −1 at 350 mV. Time-resolved measurements of direct emission spectra for nitrogen second positive system N 2 (C-B) were measured in the DBD microplasma discharge. And a high vibrational temperature ( T vib , 3100 K) and rotational temperature ( T rot , 340 K) were obtained, indicating a great chemical reactivity. In addition, the intermediate products of hydroxyl radicals ( · OH) were identified and the possible synthesis mechanism was tentatively proposed. Graphical abstract A fast and facile approach was designed to fabricate NiFe LDH-Ci/CC by DBD microplasma.

Background The coronavirus disease 2019 (COVID-19) pandemic is having a profound impact on the health and development of children worldwide. There is limited evidence on the impact of COVID-19 and its related school closures and disease-containment measures on the psychosocial wellbeing of children; little research has been done on the characteristics of vulnerable groups and factors that promote resilience. Methods We conducted a large-scale cross-sectional population study of Hong Kong families with children aged 2–12 years. Parents completed an online survey on family demographics, child psychosocial wellbeing, functioning and lifestyle habits, parent–child interactions, and parental stress during school closures due to COVID-19. We used simple and multiple linear regression analyses to explore factors associated with child psychosocial problems and parental stress during the pandemic. Results The study included 29,202 individual families; of which 12,163 had children aged 2–5 years and 17,029 had children aged 6–12 years. The risk of child psychosocial problems was higher in children with special educational needs, and/or acute or chronic disease, mothers with mental illness, single-parent families, and low-income families. Delayed bedtime and/or inadequate sleep or exercise duration, extended use of electronic devices were associated with significantly higher parental stress and more psychosocial problems among pre-schoolers. Conclusions This study identifies vulnerable groups of children and highlights the importance of strengthening family coherence, adequate sleep and exercise, and responsible use of electronic devices in promoting psychosocial wellbeing during the COVID-19 pandemic.

The spike (S) protein of SARS-CoV-2 has been observed in three distinct pre-fusion conformations: locked, closed and open. Of these, the function of the locked conformation remains poorly understood. Here we engineered a SARS-CoV-2 S protein construct “S-R/x3” to arrest SARS-CoV-2 spikes in the locked conformation by a disulfide bond. Using this construct we determined high-resolution structures confirming that the x3 disulfide bond has the ability to stabilize the otherwise transient locked conformations. Structural analyses reveal that wild-type SARS-CoV-2 spike can adopt two distinct locked-1 and locked-2 conformations. For the D614G spike, based on which all variants of concern were evolved, only the locked-2 conformation was observed. Analysis of the structures suggests that rigidified domain D in the locked conformations interacts with the hinge to domain C and thereby restrains RBD movement. Structural change in domain D correlates with spike conformational change. We propose that the locked-1 and locked-2 conformations of S are present in the acidic high-lipid cellular compartments during virus assembly and egress. In this model, release of the virion into the neutral pH extracellular space would favour transition to the closed or open conformations. The dynamics of this transition can be altered by mutations that modulate domain D structure, as is the case for the D614G mutation, leading to changes in viral fitness. The S-R/x3 construct provides a tool for the further structural and functional characterization of the locked conformations of S, as well as how sequence changes might alter S assembly and regulation of receptor binding domain dynamics.

An examination of the receptor-binding properties of the H7N9 virus, which has recently emerged in China, shows that the virus has acquired the ability to bind the human α-2,6-linked sialic acid receptor while retaining binding to the avian α-2,3-linked receptor, and therefore does not have the preference for human versus avian receptors characteristic of pandemic viruses. H7N9 avian flu virus isolates examined The H7N9 avian flu virus emerged in the human population on mainland China in February 2013, and by the first week of July WHO had recorded 133 cases including 43 deaths. Most cases so far have been linked to live bird markets. In this issue of Nature two groups report on the receptor-binding properties of H7N9. Both find that the virus has acquired the ability to bind the human α-2,3-linked sialic acid receptor yet has a retained preference for binding to the avian 2,3-linked receptor, a factor that may restrict its further evolution towards efficient transmission between humans. Steven Gamblin and colleagues also solve the crystal structure of the H7 haemagglutinin in complex with the receptor analogues, revealing details of how the human-receptor-binding properties may have arisen. Yuelong Shu and colleagues examine the pattern of virus infection in lung tissue. In human tracheal and lung explants, the virus infects epithelial cells in the lower respiratory tract and type II pneumocytes in the alveoli, and is better able to replicate in the lower respiratory tract compared with the trachea, a possible factor in the inefficient human-to-human transmission seen to date. They also report hypercytokinaemia in some patients — a cytokine storm that can contribute to disease severity — comparable to that seen in some H5N1 infections. Of the 132 people known to have been infected with H7N9 influenza viruses in China, 37 died, and many were severely ill 1 . Infection seems to have involved contact with infected poultry 2 , 3 . We have examined the receptor-binding properties of this H7N9 virus and compared them with those of an avian H7N3 virus. We find that the human H7 virus has significantly higher affinity for α-2,6-linked sialic acid analogues (‘human receptor’) than avian H7 while retaining the strong binding to α-2,3-linked sialic acid analogues (‘avian receptor’) characteristic of avian viruses. The human H7 virus does not, therefore, have the preference for human versus avian receptors characteristic of pandemic viruses. X-ray crystallography of the receptor-binding protein, haemagglutinin (HA), in complex with receptor analogues indicates that both human and avian receptors adopt different conformations when bound to human H7 HA than they do when bound to avian H7 HA. Human receptor bound to human H7 HA exits the binding site in a different direction to that seen in complexes formed by HAs from pandemic viruses 4 , 5 and from an aerosol-transmissible H5 mutant 6 . The human-receptor-binding properties of human H7 probably arise from the introduction of two bulky hydrophobic residues by the substitutions Gln226Leu and Gly186Val. The former is shared with the 1957 H2 and 1968 H3 pandemic viruses and with the aerosol-transmissible H5 mutant. We conclude that the human H7 virus has acquired some of the receptor-binding characteristics that are typical of pandemic viruses, but its retained preference for avian receptor may restrict its further evolution towards a virus that could transmit efficiently between humans, perhaps by binding to avian-receptor-rich mucins in the human respiratory tract 7 rather than to cellular receptors.

Sir2-HerA is a widely distributed antiphage system composed of a RecA-like ATPase (HerA) and an effector with potential NADase activity (Sir2). Sir2-HerA is believed to provide defense against phage infection in Sir2-dependent NAD + depletion to arrest the growth of infected cells. However, the detailed mechanism underlying its antiphage activity remains largely unknown. Here, we report functional investigations of Sir2-HerA from Staphylococcus aureus ( Sa Sir2-HerA), unveiling that the NADase function of Sa Sir2 can be allosterically activated by the binding of Sa HerA, which then assembles into a supramolecular complex with NADase activity. By combining the cryo-EM structure of Sa Sir2-HerA in complex with the NAD + cleavage product, it is surprisingly observed that Sir2 protomers that interact with HerA are in the activated state, which is due to the opening of the α15-helix covering the active site, allowing NAD + to access the catalytic pocket for hydrolysis. In brief, our study provides a comprehensive view of an allosteric activation mechanism for Sir2 NADase activity in the Sir2-HerA immune system. Deletion of cellular NAD+ via Sir2-depentent NADase provides immunity against phage infection in the Sir2-HerA immune system. Here the authors reveal supramolecular assembly for the allosteric activation on Sir2 NADase function in the Sir2-HerA antiphage system.

Influenza viruses and thogotoviruses account for most recognized orthomyxoviruses. Thogotoviruses, exemplified by Thogoto virus (THOV), are capable of infecting humans using ticks as vectors. THOV transcribes mRNA without the extraneous 5′ end sequences derived from cap-snatching in influenza virus mRNA. Here, we report cryo-EM structures to characterize THOV polymerase RNA synthesis initiation and elongation. The structures demonstrate that THOV RNA transcription and replication are able to start with short dinucleotide primers and that the polymerase cap-snatching machinery is likely non-functional. Triggered by RNA synthesis, asymmetric THOV polymerase dimers can form without the involvement of host factors. We confirm that, distinctive from influenza viruses, THOV-polymerase RNA synthesis is weakly dependent of the host factors ANP32A/B/E in human cells. This study demonstrates varied mechanisms in RNA synthesis and host factor utilization among orthomyxoviruses, providing insights into the mechanisms behind thogotoviruses’ broad-infectivity range. In this study the authors present the Thogoto virus polymerase cryo-EM structures and reveal unique RNA synthesis mechanisms among orthomyxoviruses. RNA synthesis by Thogoto virus polymerase is shown to be weakly dependent on the host factors ANP32A/B/E in human cells in contrast to influenza viruses.