Superhydrophobic Co/Fe sulfide nanoparticles and single-atoms doped carbon nanosheets composite air cathode for high-performance zinc-air batteries

Development of a high-performance bifunctional catalyst is essential for the actual implementation of zinc-air batteries in practical applications.Herein,a bifunctional cathode of Co_(3)S_(4)/FeS heterogeneous nanoparticles embedded in Co/Fe single-atom-loaded nitrogen-doped carbon nanosheets is designed.Cobalt-iron sulfides and single atomic sites with Co-N_(4)/Fe-N_(4)configurations are confirmed to coexist on the carbon matrix by EXAFS spectroscopy.3D self-supported super-hydrophobic multiphase composite cathode provides abundant active sites and facilitates gas–liquid-solid three-phase interface reactions,resulting in excellent electrocatalytic activity and batteries performance,i.e.,an OER overpotential(η_(10))of 260 mV,a half-wave potential(E_(1/2))of 0.872 V for ORR,aΔE of 0.618 V,and a discharge power density of 170 mW cm^(−2),a specific capacity of 816.3 mAh g^(−1).DFT analysis shows multiphase coupling of sulfide heterojunction through single-atomic metal doped carbon nanosheets reduces offset on center of electronic density of states before and after oxygen adsorption,and spin density of adsorbed oxygen with same spin orientation,leading to weakened charge/spin interactions between adsorbed oxygen and substrate,and a lowered oxygen adsorption energy to accelerate OER/ORR.

Effects of COVID-19 on the cardiovascular system:A mendelian randomization study

Infections with the coronavirus disease 2019(COVID-19)and disorders of the heart and blood vessels are causally related.To ascertain the causal relationship between COVID-19 and cardiovascular disease(CVD),we carried out a Mendelian randomization(MR)study through a method known as inverse variance weighting(IVW).When analyzing multiple SNPs,MR can meta-aggregate the effects of multiple loci by using IVW meta-pooling method.The weighted median(WM)is the median of the distribution function obtained by ranking all individual SNP effect values according to their weights.WM yields robust estimates when at least 50%of the information originates from valid instrumental variables(IVs).Directed gene pleiotropy in the included IVs is permitted because MR–Egger does not require a regression straight line through the origin.For MR estimation,IVW,WM and MR-Egger were employed.Sensitivity analysis was conducted using funnel plots,Cochran's Q test,MR–Egger intercept test,MR–PRESSO,and leave-one-out analysis.SNPs related to exposure to COVID-19 and CVD were compiled.CVD for COVID-19 infection,COVID-19 laboratory/self-reported negative,and other very severe respiratory diagnosis and population were randomly assigned using MR.The COVID-19 laboratory/self-reported negative results and other very severe respiratory confirmed cases versus MR analysis of CVD in the population(p>0.05);COVID-19 infection to CVD(p?0.033,OR?1.001,95%CI:1.000–1.001);and the MR–Egger results indicated that COVID-19 infection was associated with CVD risk.This MR study provides preliminary evidence for the validity of the causal link between COVID-19 infection and CVD.