Electrochemical Carbon Dioxide Reduction to Ethylene:From Mechanistic Understanding to Catalyst Surface Engineering

Electrochemical carbon dioxide reduction reaction(CO_(2)RR)provides a promising way to convert CO_(2)to chemicals.The multicarbon(C_(2+))products,especially ethylene,are of great interest due to their versatile industrial applications.However,selectively reducing CO_(2)to ethylene is still challenging as the additional energy required for the C–C coupling step results in large overpotential and many competing products.Nonetheless,mechanistic understanding of the key steps and preferred reaction pathways/conditions,as well as rational design of novel catalysts for ethylene production have been regarded as promising approaches to achieving the highly efficient and selective CO_(2)RR.In this review,we first illustrate the key steps for CO_(2)RR to ethylene(e.g.,CO_(2)adsorption/activation,formation of~*CO intermediate,C–C coupling step),offering mechanistic understanding of CO_(2)RR conversion to ethylene.Then the alternative reaction pathways and conditions for the formation of ethylene and competitive products(C_1 and other C_(2+)products)are investigated,guiding the further design and development of preferred conditions for ethylene generation.Engineering strategies of Cu-based catalysts for CO_(2)RR-ethylene are further summarized,and the correlations of reaction mechanism/pathways,engineering strategies and selectivity are elaborated.Finally,major challenges and perspectives in the research area of CO_(2)RR are proposed for future development and practical applications.

Multi-proxy reconstructions of hydrological changes from continental shelf sediments in the northern South China Sea during the interval 9200–6200 cal a BP

Past hydroclimatic conditions in southern China are poorly constrained owing to the lack of high-resolution marine-sediment records. In this study, we present high-resolution geochemical and grain-size records of marine sediments from the coastal shelf of the northern South China Sea to investigate regional hydrological variations.Results suggest a warm and humid climate during the interval 9 200–7 600 cal a BP, followed by a cold and dry climate from 7 600 cal a BP to 6 500 cal a BP, and progressive humidification during the period 6 500–6 200 cal a BP.A prominent hydrological anomaly occurred during 7 600–6 500 cal a BP. This abrupt event corresponds closely to tropical Pacific and interhemispheric temperature gradients, suggesting that moisture variations in southern China may have been driven by interhemispheric and zonal Pacific temperature gradients via modulation of the intensity and location of the West Pacific subtropical high.

Enhanced confinement synthesis of atomically dispersed Fe-N-C catalyst from resin polymer for oxygen reduction

Due to larger atom utilization,unique electronic properties and unsaturated coordination,atomically dispersed non-precious metal catalysts with outstanding performances have received great attention in electrocatalysis.Considering the challenge of serious aggregation,rational synthesis of an atomic catalyst with good dispersion of atoms is paramount to the development of these catalysts.Herein,we report an enhanced confinement strategy to synthesize a catalyst comprised of atomically dispersed Fe supported on porous nitrogen-doped graphitic carbon from the novel and more cross-linkable Melamine-Glyoxal Resin.Densified isolated grid trapping,excessive melamine restricting,and nitrogen anchoring are strongly combined to ensure the final atomic-level dispersion of metal atoms.Experimental studies revealed enhanced kinetics of the obtained catalyst towards oxygen reduction reaction(ORR).This catalytic activity originates from the highly active surface with atomically dispersed iron sites as well as the multi-level three-dimensional structure with fast mass and electron transfer.The enhanced confinement strategy endows the resin-derived atomic catalyst with a great prospect to develop for commercialization in future.

Transcriptome wide association studies: general framework and methods

Background:Genome-wide association studies(GWAS)have succeeded in identifying tens of thousands of genetic variants associated with complex human traits during the past decade,however,they are still hampered by limited statistical power and difficulties in biological interpretation.With the recent progress in expression quantitative trait loci(eQTL)studies,transcriptome-wide association studies(TWAS)provide a framework to test for gene-trait associations by integrating information from GWAS and eQTL studies.Results:In this review,we will introduce the general framework of TWAS,the relevant resources,and the computational tools.Extensions of the original TWAS methods will also be discussed.Furthermore,we will briefly introduce methods that are closely related to TWAS,including MR-based methods and colocalization approaches.Connection and difference between these approaches will be discussed.Conclusion:Finally,we will summarize strengths,limitations,and potential directions for TWAS.

Electromechanical behavior of fiber-reinforced dielectric elastomer membrane

Based on its large deformation,light weight,and high energy density,dielectric elastomer(DE)has been used as driven muscle in many areas.We design the fiberreinforced DE membrane by adding fibers in the membrane.The deformation and driven force direction of the membrane can be tuned by changing the fiber arrangements.The actuation in the perpendicular direction of the DE membrane with long fibers first increases and then decreases by the increasing of the fiber spacing in the perpendicular direction.The horizontal actuation of the membrane decreases by decreasing the spacing of short fibers.In the membrane-inflating structure,the radially arranged fibers will break the axisymmetric behavior of the structure.The top area of the inflated balloon without fiber will buckle up when the voltage reaches a certain level.Finite element simulations based on nonlinear field theory are conducted to investigate the effects of fiber arrangement and verify the experimental results.This work can guide the design of fiber-reinforced DE.