As a new frontier in catalysis field,single-atom catalysts(SACs)hold unique electronic structure and high atom utilization,which have displayed unprecedented activity and selectivity toward a wide range of catalytic r...As a new frontier in catalysis field,single-atom catalysts(SACs)hold unique electronic structure and high atom utilization,which have displayed unprecedented activity and selectivity toward a wide range of catalytic reactions.However,many reported SACs are susceptible to Ostwald ripening process in high temperature environment or long-term catalytic application,which will cause sintering and deactivation.This is due to the weak interaction between the metal atom and supports.The regeneration and recycling of deactivated catalysts will greatly increase the time and economic cost of industrial production.Therefore,it is necessary to develop SACs with excellent thermal stability to meet the industrial demands.Here,we discuss the fundamental comprehension of the stability of thermally stable SACs obtained from different synthesis methods.The influences of the speciation of metal centers and coordination environments on thermal stability are summarized.The importance of using novel in situ and operando characterizations to reveal dynamic structural evolution under synthesis and reaction conditions and to identify active sites of thermally stable SACs is highlighted.The mechanistic understanding of the unique role of thermally stable SACs in thermocatalytic application is also discussed.At last,a brief perspective on the remaining challenges and future directions of thermally stable SACs is presented.展开更多
The BeiDou-3 navigation satellite system(BDS-3)provides a full-domain high-precision positioning service for the power system to ensure safe and stable operation.However,BDS-3 power system positioning faces certain ch...The BeiDou-3 navigation satellite system(BDS-3)provides a full-domain high-precision positioning service for the power system to ensure safe and stable operation.However,BDS-3 power system positioning faces certain challenges,such as complex electromagnetic interference and incomplete error elimination.Herein,a back propagation neural network-improved least mean square(BP-LMS)adaptive filtering method is proposed for the BDS-3 full-domain and high-precision power system positioning,which utilizes the loss function to update the weight of the BP hidden layer,computes the pseudo compensation range,and eliminates the impact of electromagnetic interference to enhance the accuracy of power system positioning.Simulation results confirm the superior performance of BP-LMS in positioning accuracy and error elimination.Compared with LMS and normalized least mean square(NLMS),the filtering error of the proposed BP-LMS adaptive filtering method is decreased by 57.14%and 51.38%,respectively.展开更多
Electrochemical impedance spectroscopy(EIS)is a well-established non-destructive characterization technique for assessing the efficacy of electrochemical energy storage and conversion systems.Electrocatalytic systems ...Electrochemical impedance spectroscopy(EIS)is a well-established non-destructive characterization technique for assessing the efficacy of electrochemical energy storage and conversion systems.Electrocatalytic systems based on proton exchange membrane(PEM),including PEM fuel cells and PEM water electrolyzers,play a crucial role in renewable energy conversion through electricity–hydrogen interconversion.EIS,along with its derived analysis methods—equivalent circuit model(ECM),distribution of relaxation time(DRT),and dynamic EIS(DEIS),is widely utilized to extract valuable kinetics and impedance data.The acquired information affords critical insights into processes such as mass transfer,charge transfer,and proton transfer within PEM systems.This mini review surveys the role of EIS in optimizing components and investigating operational conditions to enhance the efficiency of PEM systems.In addition,it encapsulates the principles and applications of EIS-based methods like DRT and DEIS,highlighting their potential in the practical application of PEM systems.展开更多
To help in the prevention of large-scale loss of agricultural production caused by crop pests,a visual analysis was performed on the main research areas,key countries,organizational cooperation,citation sources and cu...To help in the prevention of large-scale loss of agricultural production caused by crop pests,a visual analysis was performed on the main research areas,key countries,organizational cooperation,citation sources and current trends in pest research by searching the literature of Web of Science database and using CiteSpace 5.8.R3 and VOSviewer 1.6.18 software.Additionally,the effects and mechanisms of natural products with anti-insect activity were summarized through visual analysis.According to the bibliometric analysis,keywords such as mortality(232 occurrences),natural enemy(232 occurrences)and spinosad(110 occurrences)were common,and insecticides and natural enemies of pests were the main methods for killing pests.However,pesticide use exhibits numerous limitations.Co-occurring terms in visualization analysis mainly included residue(193 occurrences),detection(153 occurrences),degradation(133 occurrences),recovery(103 occurrences),pyrethroid(97 occurrences)and pesticide residues(65 occurrences).Thus,pesticides cannot fundamentally solve food security;pesticides also pollute the environment and endanger human health.Therefore,green and efficient pesticides that can replace synthetic pesticides are urgently needed.Natural products have recently gained attention in Brazil,China,the USA and other countries because they are green and pollution-free,and new natural pesticides have been developed.This visual analysis combined data mining with literature review and summarize the anti-pest activities and mechanisms of action of natural products.This information provides a foundation and ideas for researchers to study the application and development of natural products in pest control.展开更多
文摘As a new frontier in catalysis field,single-atom catalysts(SACs)hold unique electronic structure and high atom utilization,which have displayed unprecedented activity and selectivity toward a wide range of catalytic reactions.However,many reported SACs are susceptible to Ostwald ripening process in high temperature environment or long-term catalytic application,which will cause sintering and deactivation.This is due to the weak interaction between the metal atom and supports.The regeneration and recycling of deactivated catalysts will greatly increase the time and economic cost of industrial production.Therefore,it is necessary to develop SACs with excellent thermal stability to meet the industrial demands.Here,we discuss the fundamental comprehension of the stability of thermally stable SACs obtained from different synthesis methods.The influences of the speciation of metal centers and coordination environments on thermal stability are summarized.The importance of using novel in situ and operando characterizations to reveal dynamic structural evolution under synthesis and reaction conditions and to identify active sites of thermally stable SACs is highlighted.The mechanistic understanding of the unique role of thermally stable SACs in thermocatalytic application is also discussed.At last,a brief perspective on the remaining challenges and future directions of thermally stable SACs is presented.
基金supported by the Science and Technology Project of the China Southern Power Grid Company Limited under Grant Number(GDKJXM20202001).
文摘The BeiDou-3 navigation satellite system(BDS-3)provides a full-domain high-precision positioning service for the power system to ensure safe and stable operation.However,BDS-3 power system positioning faces certain challenges,such as complex electromagnetic interference and incomplete error elimination.Herein,a back propagation neural network-improved least mean square(BP-LMS)adaptive filtering method is proposed for the BDS-3 full-domain and high-precision power system positioning,which utilizes the loss function to update the weight of the BP hidden layer,computes the pseudo compensation range,and eliminates the impact of electromagnetic interference to enhance the accuracy of power system positioning.Simulation results confirm the superior performance of BP-LMS in positioning accuracy and error elimination.Compared with LMS and normalized least mean square(NLMS),the filtering error of the proposed BP-LMS adaptive filtering method is decreased by 57.14%and 51.38%,respectively.
基金supported by the National Key R&D Program of China(2022YFB2404402)the State Grid Headquarter Science and Technology Project(5419-202399650A-3-2-ZN)+4 种基金S&T Program of Hebei(22344402D)National Natural Science Foundation of China(T2322015,22393900,and 22109086)the Beijing Natural Science Foundation(L233004)the Seed Fund of Shanxi Research Institute for Clean Energythe Tsinghua University Initiative Scientific Research Program。
文摘Electrochemical impedance spectroscopy(EIS)is a well-established non-destructive characterization technique for assessing the efficacy of electrochemical energy storage and conversion systems.Electrocatalytic systems based on proton exchange membrane(PEM),including PEM fuel cells and PEM water electrolyzers,play a crucial role in renewable energy conversion through electricity–hydrogen interconversion.EIS,along with its derived analysis methods—equivalent circuit model(ECM),distribution of relaxation time(DRT),and dynamic EIS(DEIS),is widely utilized to extract valuable kinetics and impedance data.The acquired information affords critical insights into processes such as mass transfer,charge transfer,and proton transfer within PEM systems.This mini review surveys the role of EIS in optimizing components and investigating operational conditions to enhance the efficiency of PEM systems.In addition,it encapsulates the principles and applications of EIS-based methods like DRT and DEIS,highlighting their potential in the practical application of PEM systems.
基金funded by the National Natural Science Foundation of China(M2042003)the Science and Technology Planning Project of the Inner Mongolia Autonomous Region,China(2021GG0377)。
文摘To help in the prevention of large-scale loss of agricultural production caused by crop pests,a visual analysis was performed on the main research areas,key countries,organizational cooperation,citation sources and current trends in pest research by searching the literature of Web of Science database and using CiteSpace 5.8.R3 and VOSviewer 1.6.18 software.Additionally,the effects and mechanisms of natural products with anti-insect activity were summarized through visual analysis.According to the bibliometric analysis,keywords such as mortality(232 occurrences),natural enemy(232 occurrences)and spinosad(110 occurrences)were common,and insecticides and natural enemies of pests were the main methods for killing pests.However,pesticide use exhibits numerous limitations.Co-occurring terms in visualization analysis mainly included residue(193 occurrences),detection(153 occurrences),degradation(133 occurrences),recovery(103 occurrences),pyrethroid(97 occurrences)and pesticide residues(65 occurrences).Thus,pesticides cannot fundamentally solve food security;pesticides also pollute the environment and endanger human health.Therefore,green and efficient pesticides that can replace synthetic pesticides are urgently needed.Natural products have recently gained attention in Brazil,China,the USA and other countries because they are green and pollution-free,and new natural pesticides have been developed.This visual analysis combined data mining with literature review and summarize the anti-pest activities and mechanisms of action of natural products.This information provides a foundation and ideas for researchers to study the application and development of natural products in pest control.
