Lithium−sulfur (Li−S) batteries suffer from multiple complex and often interwoven issues, such as the low electronic conductivity of sulfur and Li 2 S/Li 2 S 2 , shuttle effect, and sluggish electrochemical kinetics of lithium polysulfides (LiPSs). Guided by theoretical calculations, a multifunctional catalyst of isolated single-atom nickel in an optimal Ni−N 5 active moiety incorporated in hollow nitrogen-doped porous carbon (Ni−N 5 /HNPC) is constructed and acts as an ideal host for a sulfur cathode. The host improved electrical conductivity, enhanced physical-chemical dual restricting capability toward LiPSs, and, more importantly, boosted the redox reaction kinetics by the Ni−N 5 active moiety. Therefore, the Ni−N 5 /HNPC/S cathode exhibits superior rate performance, long-term cycling stability, and good areal capacity at high sulfur loading. This work highlights the important role of the coordination number of active centers in single-atom catalysts and provides a strategy to design a hollow nanoarchitecture with single-atom active sites for high-performance Li−S batteries.

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Background and Aim: To compare the efficacy and safety of esophagogastroduodenoscopy (EGD)-colonoscopy and colonoscopy-EGD sequences for patients subjected to same-day bidirectional endoscopy under remifentanil and propofol sedation.Methods: A total of 209 eligible outpatients scheduled for diagnostic same-day bidirectional endoscopy between 16 February 2016 and 30 April 2016 were randomly assigned to the EGDcolonoscopy (n = 106) and colonoscopy-EGD (n = 103) sequence groups. Primary endpoint was total dose of propofol required for the procedure. Secondary endpoints included duration of endoscopy, patient satisfaction, adverse effects, endoscopy findings, and cardiopulmonary responses of the patients.Results: Patients in the two groups were similar in terms of demographic and clinical data (P > 0.05). EGD-colonoscopy sequence group had lesser requirement of propofol for sedation (P < 0.05), faster recovery (P < 0.001), and lesser influence on mean arterial pressure (MAP) during the endoscopy (P < 0.05). Duration of EGD and colonoscopy, patient satisfaction, adverse effects, and pathological findings did not differ between the two groups. Conclusions:The EGD-colonoscopy sequence may be considered the preferred sequence for same-day bidirectional endoscopy as a result of less cardiovascular stress, lessened need for sedation with propofol, and faster recovery.

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