Iron and nitrogen codoped carbons (Fe-N-C) have attracted increasingly greater attention as electrocatalysts for oxygen reduction reaction (ORR). Although challenging, the synthesis of Fe-N-C catalysts with highly dispersed and fully exposed active sites is of critical importance for improving the ORR activity. Here, we report a new type of graphitic Fe-N-C catalysts featuring numerous Fe single atoms anchored on a three-dimensional simple-cubic carbon framework. The Fe-N-C catalyst, derived from self-assembled FeO nanocube superlattices, was prepared by in situ ligand carbonization followed by acid etching and ammonia activation. Benefiting from its homogeneously dispersed and fully accessible active sites, highly graphitic nature, and enhanced mass transport, our Fe-N-C catalyst outperformed Pt/C and many previously reported Fe-N-C catalysts for ORR. Furthermore, when used for constructing the cathode for zinc-air batteries, our Fe-N-C catalyst exhibited current and power densities comparable to those of the state-of-the-art Pt/C catalyst.

Fine‐tuning strain and vacancies in 2H‐phase transition‐metal dichalcogenides, although extremely challenging, is crucial for activating the inert basal plane for boosting the hydrogen evolution reaction (HER). Here, atomically curved 2H‐WS2 nanosheets with precisely tunable strain and sulfur vacancies (S‐vacancies) along with rich edge sites are synthesized via a one‐step approach by harnessing geometric constraints. The approach is based on the confined epitaxy growth of WS2 in ordered mesoporous graphene derived from nanocrystal superlattices. The spherical curvature imposed by the graphitic mesopores enables the generation of uniform strain and S‐vacancies in the as‐grown WS2 nanosheets, and simultaneous manipulation of these two key parameters can be realized by simply adjusting the pore size. In addition, the formation of unique mesoporous WS2@graphene van der Waals heterostructures ensures the ready access of active sites. Fine‐tuning the WS2 layer number, strain, and S‐vacancies enables arguably the best‐performing HER 2H‐WS2 electrocatalysts ever reported. Density functional theory calculations indicate that compared with strain, S‐vacancies play a more critical role in enhancing the HER activity.

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pneumonia" OR " coronavirus"), AND " Myocarditis" OR " Cycle threshold (Ct)" OR " Altitude". We found that one article analyzed the risk factors affecting the prognosis of adult patients with COVID-19 in terms of survivorship, without considering Ct values as extrinsic factors.Moreover, there are no reported studies on viral myocarditis caused by COVID-19 and the relationship between the altitude and COVID-19. Added value of this studyWe retrospectively analyzed the clinical data, Ct values, laboratory indicators and imaging findings of 84 adult patients with confirmed COVID-19. Three key-independent risk factors of COVID-19 were identified in our study, including age [OR 2.350; 95% CI (1.206 to 4.580); p=0.012], Ct value [OR 0.158; 95% CI (0.025 to 0.987); p=0.048] and PII [OR 1.912; 95% CI (1.187 to 3.079); p=0.008]. Amongst 84 patients, 13 patients (15.48%) were noted with abnormal electrocardiograms (ECGs) and serum myocardial enzyme levels; whereas 4 (4.8%) were clinically diagnosed as SARS-CoV-2 myocarditis. Moreover, altitude should be considered for COVID-19 severity classification, given that oxygen partial pressure and blood oxygen saturation of regional patients vary with altitudes.