SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is the etiological agent responsible for the global COVID-19 (coronavirus disease 2019) outbreak. The main protease of SARS-CoV-2, Mpro, is a key enzyme that plays a pivotal role in mediating viral replication and transcription. We designed and synthesized two lead compounds (11a and 11b) targeting Mpro. Both exhibited excellent inhibitory activity and potent anti–SARS-CoV-2 infection activity. The x-ray crystal structures of SARS-CoV-2 Mpro in complex with 11a or 11b, both determined at a resolution of 1.5 angstroms, showed that the aldehyde groups of 11a and 11b are covalently bound to cysteine 145 of Mpro. Both compounds showed good pharmacokinetic properties in vivo, and 11a also exhibited low toxicity, which suggests that these compounds are promising drug candidates.

Introducing oxygen vacancies into metal oxides is a promising strategy to promote their catalytic activity, which has been extensively studied in heterogeneous catalysis. Herein, transition metal (M = Fe, Co, and Ni) doping was used to introduce oxygen vacancies in CeO 2 and promote activity for carbonyl sulfide (COS) hydrolysis. Various techniques were performed to accurately characterize the catalyst structure and state. The transition metals successfully entered the crystal lattice of CeO 2 and formed a solid solution structure. The metal-doped CeO 2 (M/CeO 2 ) showed improved reduction properties, more Ce 3+ and oxygen vacancies in comparison with pure CeO 2 . The introduction of transition metal greatly enhanced activity of M/CeO 2 for COS hydrolysis. Among them, the Co/CeO 2 sample displayed the highest activity and H 2 S selectivity. The roles of metal doping in improving activity were explored on the basis of DFT calculations. The strong interaction between doped metals and CeO 2 promotes the spontaneous formation of asymmetric oxygen vacancies in M/CeO 2 . These asymmetric oxygen vacancies facilitate the activation and dissociation of H 2 O and generation of active hydroxyls, which contributes to the enhanced activity for COS hydrolysis. This work provides an attractive method for obtaining nonprecious metal catalysts for COS hydrolysis.

Objective: Chinese pediatricians are working on the front line to fight COVID-19. They have published a great amount of first-hand clinical data. Collecting their data and forming a large sample for analysis is more conducive to the recognition, prevention and treatment of coronavirus disease 2019 in children. The epidemic prevention and control experience of Chinese pediatricians should be shared with the world. Methods: By searching Chinese and English literature, the data of 406 children with COVID-19 in China were analyzed. Results: It was found that the clustered incidence of children's families is a dynamic transmission feature; the incidence is low; asymptomatic infections and mild cases account for 44.8%, with only 7 cases of critical illness; laboratory examination of lymphocyte counts is not reduced, as it is for adults; chest CT findings are less severe than those for adults. These presentations are the clinical features of COVID-19 in children. Only 55 of the 406 cases were tested by anal swab for virus nucleic acid, 45 of which were positive, accounting for 81.8% of stool samples. Conclusion: There are more children than adults with asymptomatic infections, milder conditions, faster recovery, and a better prognosis. Some concealed morbidity characteristics also bring difficulties to the early identification, prevention and control of COVID-19. COVID-19 screening is needed in the pediatric fever clinic, and respiratory and digestive tract nucleic acid tests should be performed. Efforts should be made to prevent children from becoming a hidden source of transmission in kindergartens, schools or families. Furthermore, China's experience in treating COVID-19 in children has led to faster recovery of sick children.