Environmental problems caused by traditional power production and the unbalanced distribution of energy resources and demand limit the development of sustainable societies. A feasible method to optimize the resource a...Environmental problems caused by traditional power production and the unbalanced distribution of energy resources and demand limit the development of sustainable societies. A feasible method to optimize the resource allocation has been proposed, and it involves cross-border and cross-regional electricity transactions. However, the uncertainty of renewable energy and the specific features of the cross-border electricity market are key issues which need to be considered in the trading mechanism design. Based on this, this paper sets up a long-term cross-border electricity trading model considering the uncertainty of renewable energy. First, annual transactions are matched according to the declared data of bidders with consideration of cross-border interconnection development benefits, potential benefit risks, and transmission costs. Second, for annual contract decomposition, the model uses the minimum generation cost function with a penalty item for power shortages to allocate electricity to each month. Additionally, the scenario reduction algorithm is combined with the unit commitment to construct a stochastic generation plan. Finally, a case study of the numerical results for the multinational electricity market in northeast Asia is used to show that the proposed trading model is feasible for cross-border electricity trading with high penetration of renewable energy.展开更多
In the past 20 years,recycled aggregate concrete(RAC),as a type of low-carbon concrete,has become a worldwide focus of research.However,the design methodology for RAC structural components remains a challenge.Conseque...In the past 20 years,recycled aggregate concrete(RAC),as a type of low-carbon concrete,has become a worldwide focus of research.However,the design methodology for RAC structural components remains a challenge.Consequently,demands for a unified design of natural aggregate concrete(NAC)and RAC components have been presented.Accordingly,this study analyses the necessity of a unified design theory and provides an in-depth demonstration of the strength determination,compressive constitutive relationship,and design method of concrete components.The coefficient of variation of RAC strength is found to be generally higher than that of NAC strength.The compressive and tensile strengths of RAC can be defined and determined using the same method as that used for NAC.The uniaxial compressive constitutive relationship between NAC and RAC has a unified mathematical expression.However,the elastic modulus of RAC decreases,and its brittleness exhibits an increasing trend compared with that of NAC.Finally,to unify the design formulae of RAC and NAC components for bearing capacity,modification factors for RAC components are proposed considering safety and reliability.Additionally,the feasibility of the proposed unified time-dependent design theory is demonstrated in terms of conceptual design and structural measures considering the effects of strength degradation and reinforcement corrosion.It is believed that this study enriches and develops the basic theory of concrete structures.展开更多
Surface chemistry modification represents a promising strategy to tailor the adsorption and activation of reaction intermediates for enhancing activity.Herein,we designed a surface oxygen-injection strategy to tune th...Surface chemistry modification represents a promising strategy to tailor the adsorption and activation of reaction intermediates for enhancing activity.Herein,we designed a surface oxygen-injection strategy to tune the electronic structure of SnS_(2) nanosheets,which showed effectively enhanced electrocatalytic activity and selectivity of CO_(2) reduction to formate and syngas(CO and H_(2)).The oxygen-injection SnS_(2) nanosheets exhibit a remarkable Faradaic efficiency of 91.6%for carbonaceous products with a current density of 24.1 mA cm^(−2) at−0.9 V vs RHE,including 83.2%for formate production and 16.5%for syngas with the CO/H_(2) ratio of 1:1.By operando X-ray absorption spectroscopy,we unravel the in situ surface oxygen doping into the matrix during reaction,thereby optimizing the Sn local electronic states.Operando synchrotron radiation infrared spectroscopy along with theoretical calculations further reveals that the surface oxygen doping facilitated the CO_(2) activation and enhanced the affinity for HCOO*species.This result demonstrates the potential strategy of surface oxygen injection for the rational design of advanced catalysts for CO_(2) electroreduction.展开更多
Decarbonization of the electricity sector is crucial to mitigate the impacts of climate change and global warming over the coming decades.The key challenges for achieving this goal are carbon emission trading and elec...Decarbonization of the electricity sector is crucial to mitigate the impacts of climate change and global warming over the coming decades.The key challenges for achieving this goal are carbon emission trading and electricity sector regulation,which are also the major components of the carbon and electricity markets,respectively.In this paper,a joint electricity and carbon market model is proposed to investigate the relationships between electricity price,carbon price,and electricity generation capacity,thereby identifying pathways toward a renewable energy transition under the transactional energy interconnection framework.The proposed model is a dynamically iterative optimization model consisting of upper-level and lower-level models.The upper-level model optimizes power generation and obtains the electricity price,which drives the lower-level model to update the carbon price and electricity generation capacity.The proposed model is verified using the Northeast Asia power grid.The results show that increasing carbon price will result in increased electricity price,along with further increases in renewable energy generation capacity in the following period.This increase in renewable energy generation will reduce reliance on carbon-emitting energy sources,and hence the carbon price will decline.Moreover,the interconnection among zones in the Northeast Asia power grid will enable reasonable allocation of zonal power generation.Carbon capture and storage (CCS) will be an effective technology to reduce the carbon emissions and further realize the emission reduction targets in 2030-2050.It eases the stress of realizing the energy transition because of the less urgency to install additional renewable energy capacity.展开更多
To clone the gene coding the immunodominant region in the chlamydial protease-like activity factor(CPAF)from Chlamydophila pneumoniae,to analyze immunocompetence of the expressed protein, and to evaluate its value in ...To clone the gene coding the immunodominant region in the chlamydial protease-like activity factor(CPAF)from Chlamydophila pneumoniae,to analyze immunocompetence of the expressed protein, and to evaluate its value in serodiagnosis,the CPAF immunodominant region gene was amplified,ligated into a pGEX6p-2 vector,and then the expressed recombinant protein was purified with glutathione S- transferase(GST)agarose gel FF after renaturation,then identified by SDS-PAGE and Western blot.A new indirect ELISA was developed with the purified protein as coating antigen.The immunogenicity of the recombinant protein was evaluated by immunization to New Zealand rabbits,and its immunoreactivity was analyzed by reacting with anti-C,pneumoniae antibody.300 clinical sera samples were respectively de- tected by microimmunofluorescence(MIF)as reference method and the indirect ELISA,and the differ- ence between the two methods was analyzed.Cross-reactivity against Chlamydia trachomatis was investi- gated with the indirect ELISA to detect anti-C,trachomatis positive antisera.The results indicated that a 51.3 kDa recombinant protein was obtained.Western blot assay proved that the recombinant protein could merely specifically react with human anti-C.pneumoniae antisera.The titers of the specific IgG an- tibodies in the immunized New Zealand rabbits were above 1:16 000.Anti-C.pneumoniae IgG positive and negative reference sere were detected with the indirect ELISA,and the concordance rate of negative and positive results were both 100%(40/40).The sensitivity and specificity of the indirect ELISA in comparison with MIF were 93.8%(45/48)and 100%(252/252)separately by detecting 300 clinical sera samples,and the concordance rate between the two methods was 99.0%.No cross reaction against C.trachomatis was found with the indirect ELISA to detect anti-C,trachomatis positive antisera.In con- clusion,the prepared recombinant protein of the CPAF immunodominant region shows excellent immuno- competence and can be used to develop a new indirect ELISA as a method to detect anti-C.pneumoniae antibody for diagnosis of C.pneumoniae infection.展开更多
The integrity and reliability of fuel rods under both normal and accidental operating conditions are of great importance for nuclear reactors.In this study,considering various irradiation behaviors,a fuel rod performa...The integrity and reliability of fuel rods under both normal and accidental operating conditions are of great importance for nuclear reactors.In this study,considering various irradiation behaviors,a fuel rod performance analysis code,named KMC-Fueltra,was developed to evaluate the thermal–mechanical performance of oxide fuel rods under both normal and transient conditions in the LMFR.The accuracy and reliability of the KMC-Fueltra were validated by analytical solutions,as well as the results obtained from codes and experiments.The results indicated that KMC-Fueltra can predict the performance of oxide fuel rods under both normal and transient conditions in the LMFR.展开更多
Interconnected power systems that link several countries and fully utilize their individual resources in a complementary manner are becoming increasingly important.As these systems enhanee accommodation of renewable e...Interconnected power systems that link several countries and fully utilize their individual resources in a complementary manner are becoming increasingly important.As these systems enhanee accommodation of renewable energy,they also represent a move toward low-carbon and low-emissi on power systems.In this paper,a low-carb on dispatch model is proposed to coo rd i nate the gen erati on output betwee n several coun tries where the carb on emissi on constraint is a priority.An adjustable robust optimization approach is used to find the optimal solution under the worst-case scenario to address the uncertainties associated with renewable energy resources.A specific constraint is that the area control error for each country should be self-balanced.Furthermore,a reformation using participation factors is presented to simplify the proposed robust dispatch model.Simulation results for practical interconnected power systems in northeast Asian countries verify the effectiveness of the proposed model.展开更多
In recent years, the global energy interconnection(GEI) has more and more profound influence around the world, which is a highly practical way for humans to handle the energy crisis. In the studies of GEI, the economi...In recent years, the global energy interconnection(GEI) has more and more profound influence around the world, which is a highly practical way for humans to handle the energy crisis. In the studies of GEI, the economic dispatch(ED) is a basic and important content. In this paper, a model of dynamic economic dispatch(DED) of GEI is presented, which include the renewable energy generation. The objective function of this model is composed of the operating costs and the renewable energy curtailment. A series of case studies for the transnational energy interconnection in Northeast Asia are given to verify the superiority of GEI and for further analysis.展开更多
Exploring the atomic interaction mechanisms of dense single-atom catalysts(SACs)is of great significance for their application in oxygen reduction reaction(ORR).However,the intrinsic mechanism of the site-distance eff...Exploring the atomic interaction mechanisms of dense single-atom catalysts(SACs)is of great significance for their application in oxygen reduction reaction(ORR).However,the intrinsic mechanism of the site-distance effect on the catalytic performance has been largely ignored.Here,we demonstrate the site-distance effect of Fe-Rh_(x)@NC catalysts in ORR theoretically and experimentally.Bader charge analysis reveals that the strong interaction between Fe and Rh atoms at a certain atomic distance(dFe-Rh)alters the catalytic electronic structure,facilitating the optimization of catalyst adsorption strength.Motivated by the theoretical calculations,we designed and synthesized the Fe-Rhx@NC catalysts through a spatial confinement strategy.The characterization results prove that the Fe-Rh_(2)@NC has the optimal d_(Fe-Rh),which improves its intrinsic ORR activity,providing a half wave potential of 0.91 V,higher than that of the commercial Pt/C(0.86 V).This study emphasizes the importance of determining the basic mechanism of the site-distance effect in dissimilar metal atoms catalysts,which is conducive to the design of efficient catalyst systems for practical applications.展开更多
Carbon-supported noble-metal-free single-atom catalysts(SACs)have aroused widespread interest due to their green chemistry aspects and excellent performances.Herein,we propose a“ligand regulation strategy”and achiev...Carbon-supported noble-metal-free single-atom catalysts(SACs)have aroused widespread interest due to their green chemistry aspects and excellent performances.Herein,we propose a“ligand regulation strategy”and achieve the successful fabrication of bifunctional SAC/MOF(MOF=metal-organic framework)nanocomposite(abbreviated NiSA/ZIF-300;ZIF=ZIF-8)with exceptional catalytic performance and robustness.The designed NiSA/ZIF-300 has a planar interfacial structure with the Ni atom,involving one S and three N atoms bonded to Ni(Ⅱ),fabricated by controllable pyrolysis of volatile Ni-S fragments.For CO_(2) cycloaddition to styrene epoxide,NiSA/ZIF-300 exhibits ultrahigh activity(turnover number(TON)=1.18×105;turnover frequency(TOF)=9830 molSC·mol_(Ni)^(-1)·h^(-1);SC=styrene carbonate)and durability at 70℃ under 1 atm CO_(2) pressure,which is much superior to Ni complex/ZIF,NiNP/ZIF-300,and most reported catalysts.This study offers a simple method of bifunctional SAC/MOF nanocomposite fabrication and usage,and provides guidance for the precise design of additional original SACs with unique catalytic properties.展开更多
This paper proposes a voltage source converter (VSC) -based AC-DC hybrid distribution system (HDS) resilient model to mitigate power outages caused by wildfires. Before a wildfire happens, the public-safety power shut...This paper proposes a voltage source converter (VSC) -based AC-DC hybrid distribution system (HDS) resilient model to mitigate power outages caused by wildfires. Before a wildfire happens, the public-safety power shutoff (PSPS) strategy is applied to actively cut some vulnerable lines which may easily cause wildfires, and reinforce some lines that are connected to critical loads. To mitigate load shedding caused by active line disconnection in the PSPS strategy, network reconfiguration is applied before the wildfire occurrence. During the restoration period, repair crews (RCs) repair faulted lines, and network reconfiguration is also taken into consideration in the recovery strategy to pick up critical loads. Since there exists possible errors in the wildfire prediction, several different scenarios of wildfire occurrence have been taken into consideration, leading to the proposition of a stochastic multi-period resilient model for the VSC-based AC-DC HDS. To accelerate the computational performance, a progressive hedging algorithm has been applied to solve the stochastic model which can be written as a mixed-integer linear program. The proposed model is verified on a 106-bus AC-DC HDS under wildfire conditions, and the result shows the proposed model not only can improve the system resilience but also accelerate computational speed.展开更多
Nasopharyngeal carcinoma(NPC)is a malignancy originating from the nasopharyngeal epithelial cells.Although some studies have identified potential biomarkers for early diagnosis of NPC based on metabolomics data(Chen e...Nasopharyngeal carcinoma(NPC)is a malignancy originating from the nasopharyngeal epithelial cells.Although some studies have identified potential biomarkers for early diagnosis of NPC based on metabolomics data(Chen et al.,2023;Zhou et al.,2023)and Epstein-Barr virus subtypes(Xu et al.,2019),their effectiveness and applicability need further investigation,particularly when consideringthe roles of oral microbiota.展开更多
Large quantities of construction and demolition(C&D)building waste are being generated as a result of rapid urbanization and natural disasters in China.An increasing awareness of environmental protection is escala...Large quantities of construction and demolition(C&D)building waste are being generated as a result of rapid urbanization and natural disasters in China.An increasing awareness of environmental protection is escalating C&D waste disposal concerns.This paper presents a brief introduction to current shaking table test research in China on structures built with recycled aggregate concrete(RAC).Test structures include a cast-in situ frame model,a precast frame model and a block masonry building.The test results prove that it is feasible to use RAC as a structural material in seismic areas,with recommended modifications and proper design,especially in low-rise structures.This paper also presents several successful applications of RAC in civil and structural engineering projects in China,which will serve to promote RAC as a global ecological structural material.展开更多
基金supported in part by National Natural Science Foundation of China(Grant 51607137)in part by China Postdoctoral Science Foundation(2017T100748)in part by the Global Energy Interconnection Group’s Science&Technology Project "The development path for electricity market and key mechanisms for grid interconnection in the context of global clean energy development"(52450018000J)
文摘Environmental problems caused by traditional power production and the unbalanced distribution of energy resources and demand limit the development of sustainable societies. A feasible method to optimize the resource allocation has been proposed, and it involves cross-border and cross-regional electricity transactions. However, the uncertainty of renewable energy and the specific features of the cross-border electricity market are key issues which need to be considered in the trading mechanism design. Based on this, this paper sets up a long-term cross-border electricity trading model considering the uncertainty of renewable energy. First, annual transactions are matched according to the declared data of bidders with consideration of cross-border interconnection development benefits, potential benefit risks, and transmission costs. Second, for annual contract decomposition, the model uses the minimum generation cost function with a penalty item for power shortages to allocate electricity to each month. Additionally, the scenario reduction algorithm is combined with the unit commitment to construct a stochastic generation plan. Finally, a case study of the numerical results for the multinational electricity market in northeast Asia is used to show that the proposed trading model is feasible for cross-border electricity trading with high penetration of renewable energy.
基金the financial support from the Distinguished Young Scholars of China by the National Natural Science Foundation of China(51325802)the National Natural Science Foundation of China(51178340,52078358,and 52008304)。
文摘In the past 20 years,recycled aggregate concrete(RAC),as a type of low-carbon concrete,has become a worldwide focus of research.However,the design methodology for RAC structural components remains a challenge.Consequently,demands for a unified design of natural aggregate concrete(NAC)and RAC components have been presented.Accordingly,this study analyses the necessity of a unified design theory and provides an in-depth demonstration of the strength determination,compressive constitutive relationship,and design method of concrete components.The coefficient of variation of RAC strength is found to be generally higher than that of NAC strength.The compressive and tensile strengths of RAC can be defined and determined using the same method as that used for NAC.The uniaxial compressive constitutive relationship between NAC and RAC has a unified mathematical expression.However,the elastic modulus of RAC decreases,and its brittleness exhibits an increasing trend compared with that of NAC.Finally,to unify the design formulae of RAC and NAC components for bearing capacity,modification factors for RAC components are proposed considering safety and reliability.Additionally,the feasibility of the proposed unified time-dependent design theory is demonstrated in terms of conceptual design and structural measures considering the effects of strength degradation and reinforcement corrosion.It is believed that this study enriches and develops the basic theory of concrete structures.
基金This work was supported by National Natural Science Foundation of China(Grants No.12025505)China Ministry of Science and Technology(2017YFA0208300)+2 种基金Youth Innovation Promotion Association CAS(CX2310007007 and CX2310000091)Open Fund Project of State Key Laboratory of Environmentally Friendly Energy Materials(20kfhg08)We would thank NSRL and SSRF for the synchrotron beam time.The calculations were performed on the supercomputing system in the Supercomputing Center of University of Science and Technology of China.
文摘Surface chemistry modification represents a promising strategy to tailor the adsorption and activation of reaction intermediates for enhancing activity.Herein,we designed a surface oxygen-injection strategy to tune the electronic structure of SnS_(2) nanosheets,which showed effectively enhanced electrocatalytic activity and selectivity of CO_(2) reduction to formate and syngas(CO and H_(2)).The oxygen-injection SnS_(2) nanosheets exhibit a remarkable Faradaic efficiency of 91.6%for carbonaceous products with a current density of 24.1 mA cm^(−2) at−0.9 V vs RHE,including 83.2%for formate production and 16.5%for syngas with the CO/H_(2) ratio of 1:1.By operando X-ray absorption spectroscopy,we unravel the in situ surface oxygen doping into the matrix during reaction,thereby optimizing the Sn local electronic states.Operando synchrotron radiation infrared spectroscopy along with theoretical calculations further reveals that the surface oxygen doping facilitated the CO_(2) activation and enhanced the affinity for HCOO*species.This result demonstrates the potential strategy of surface oxygen injection for the rational design of advanced catalysts for CO_(2) electroreduction.
基金supported in part by National Key Research and Development Program of China(2016YFB0901900)the Science and Technology Foundation of GEIDCO(SGGEIG00JYJS1900016)
文摘Decarbonization of the electricity sector is crucial to mitigate the impacts of climate change and global warming over the coming decades.The key challenges for achieving this goal are carbon emission trading and electricity sector regulation,which are also the major components of the carbon and electricity markets,respectively.In this paper,a joint electricity and carbon market model is proposed to investigate the relationships between electricity price,carbon price,and electricity generation capacity,thereby identifying pathways toward a renewable energy transition under the transactional energy interconnection framework.The proposed model is a dynamically iterative optimization model consisting of upper-level and lower-level models.The upper-level model optimizes power generation and obtains the electricity price,which drives the lower-level model to update the carbon price and electricity generation capacity.The proposed model is verified using the Northeast Asia power grid.The results show that increasing carbon price will result in increased electricity price,along with further increases in renewable energy generation capacity in the following period.This increase in renewable energy generation will reduce reliance on carbon-emitting energy sources,and hence the carbon price will decline.Moreover,the interconnection among zones in the Northeast Asia power grid will enable reasonable allocation of zonal power generation.Carbon capture and storage (CCS) will be an effective technology to reduce the carbon emissions and further realize the emission reduction targets in 2030-2050.It eases the stress of realizing the energy transition because of the less urgency to install additional renewable energy capacity.
文摘To clone the gene coding the immunodominant region in the chlamydial protease-like activity factor(CPAF)from Chlamydophila pneumoniae,to analyze immunocompetence of the expressed protein, and to evaluate its value in serodiagnosis,the CPAF immunodominant region gene was amplified,ligated into a pGEX6p-2 vector,and then the expressed recombinant protein was purified with glutathione S- transferase(GST)agarose gel FF after renaturation,then identified by SDS-PAGE and Western blot.A new indirect ELISA was developed with the purified protein as coating antigen.The immunogenicity of the recombinant protein was evaluated by immunization to New Zealand rabbits,and its immunoreactivity was analyzed by reacting with anti-C,pneumoniae antibody.300 clinical sera samples were respectively de- tected by microimmunofluorescence(MIF)as reference method and the indirect ELISA,and the differ- ence between the two methods was analyzed.Cross-reactivity against Chlamydia trachomatis was investi- gated with the indirect ELISA to detect anti-C,trachomatis positive antisera.The results indicated that a 51.3 kDa recombinant protein was obtained.Western blot assay proved that the recombinant protein could merely specifically react with human anti-C.pneumoniae antisera.The titers of the specific IgG an- tibodies in the immunized New Zealand rabbits were above 1:16 000.Anti-C.pneumoniae IgG positive and negative reference sere were detected with the indirect ELISA,and the concordance rate of negative and positive results were both 100%(40/40).The sensitivity and specificity of the indirect ELISA in comparison with MIF were 93.8%(45/48)and 100%(252/252)separately by detecting 300 clinical sera samples,and the concordance rate between the two methods was 99.0%.No cross reaction against C.trachomatis was found with the indirect ELISA to detect anti-C,trachomatis positive antisera.In con- clusion,the prepared recombinant protein of the CPAF immunodominant region shows excellent immuno- competence and can be used to develop a new indirect ELISA as a method to detect anti-C.pneumoniae antibody for diagnosis of C.pneumoniae infection.
文摘The integrity and reliability of fuel rods under both normal and accidental operating conditions are of great importance for nuclear reactors.In this study,considering various irradiation behaviors,a fuel rod performance analysis code,named KMC-Fueltra,was developed to evaluate the thermal–mechanical performance of oxide fuel rods under both normal and transient conditions in the LMFR.The accuracy and reliability of the KMC-Fueltra were validated by analytical solutions,as well as the results obtained from codes and experiments.The results indicated that KMC-Fueltra can predict the performance of oxide fuel rods under both normal and transient conditions in the LMFR.
基金the Science and Technology Foundation of Global Energy Interconnection Group Co.,Ltd.(No.524500180012)National Natural Science Foundation of China(No.51977166).
文摘Interconnected power systems that link several countries and fully utilize their individual resources in a complementary manner are becoming increasingly important.As these systems enhanee accommodation of renewable energy,they also represent a move toward low-carbon and low-emissi on power systems.In this paper,a low-carb on dispatch model is proposed to coo rd i nate the gen erati on output betwee n several coun tries where the carb on emissi on constraint is a priority.An adjustable robust optimization approach is used to find the optimal solution under the worst-case scenario to address the uncertainties associated with renewable energy resources.A specific constraint is that the area control error for each country should be self-balanced.Furthermore,a reformation using participation factors is presented to simplify the proposed robust dispatch model.Simulation results for practical interconnected power systems in northeast Asian countries verify the effectiveness of the proposed model.
基金supported in part by National Key Research and Development Program of China(2016YFB0901900)in part by the Science and Technology Project of SGCC-Research on Grid Dispatching and Transaction Mode for Global Energy Interconnection+2 种基金in part by China Postdoctoral Science Foundation(2017T100748)in part by Natural Science Basis Research Plan in Shaanxi Province of China(2016JQ5015)in part by the project of State Key Laboratory of Electrical Insulation and Power Equipment in Xi’an Jiaotong University(EIPE17205,EIPE16301)
文摘In recent years, the global energy interconnection(GEI) has more and more profound influence around the world, which is a highly practical way for humans to handle the energy crisis. In the studies of GEI, the economic dispatch(ED) is a basic and important content. In this paper, a model of dynamic economic dispatch(DED) of GEI is presented, which include the renewable energy generation. The objective function of this model is composed of the operating costs and the renewable energy curtailment. A series of case studies for the transnational energy interconnection in Northeast Asia are given to verify the superiority of GEI and for further analysis.
基金supported by the National Key R&D Program of China(2021YFA1600800 and 2020YFA0710203)the National Natural Science Foundation of China(12025505,22002147,22179125 and 12205304)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0450200)the University of China Innovation Program of Anhui Province(GXXT-2020-053)the Youth Innovation Promotion Association CAS(2015366 and 2022458)the Fellowship of China Postdoctoral Science Foundation(2021TQ0319)。
文摘Exploring the atomic interaction mechanisms of dense single-atom catalysts(SACs)is of great significance for their application in oxygen reduction reaction(ORR).However,the intrinsic mechanism of the site-distance effect on the catalytic performance has been largely ignored.Here,we demonstrate the site-distance effect of Fe-Rh_(x)@NC catalysts in ORR theoretically and experimentally.Bader charge analysis reveals that the strong interaction between Fe and Rh atoms at a certain atomic distance(dFe-Rh)alters the catalytic electronic structure,facilitating the optimization of catalyst adsorption strength.Motivated by the theoretical calculations,we designed and synthesized the Fe-Rhx@NC catalysts through a spatial confinement strategy.The characterization results prove that the Fe-Rh_(2)@NC has the optimal d_(Fe-Rh),which improves its intrinsic ORR activity,providing a half wave potential of 0.91 V,higher than that of the commercial Pt/C(0.86 V).This study emphasizes the importance of determining the basic mechanism of the site-distance effect in dissimilar metal atoms catalysts,which is conducive to the design of efficient catalyst systems for practical applications.
基金support by the National Natural Science Foundation of China(Nos.21972001,21871001)the Natural Science Foundation of Anhui Province(No.2008085MB37)the Anhui University,the University of Bordeaux,and the Centre National de la Recherche Scientifique(CNRS).
文摘Carbon-supported noble-metal-free single-atom catalysts(SACs)have aroused widespread interest due to their green chemistry aspects and excellent performances.Herein,we propose a“ligand regulation strategy”and achieve the successful fabrication of bifunctional SAC/MOF(MOF=metal-organic framework)nanocomposite(abbreviated NiSA/ZIF-300;ZIF=ZIF-8)with exceptional catalytic performance and robustness.The designed NiSA/ZIF-300 has a planar interfacial structure with the Ni atom,involving one S and three N atoms bonded to Ni(Ⅱ),fabricated by controllable pyrolysis of volatile Ni-S fragments.For CO_(2) cycloaddition to styrene epoxide,NiSA/ZIF-300 exhibits ultrahigh activity(turnover number(TON)=1.18×105;turnover frequency(TOF)=9830 molSC·mol_(Ni)^(-1)·h^(-1);SC=styrene carbonate)and durability at 70℃ under 1 atm CO_(2) pressure,which is much superior to Ni complex/ZIF,NiNP/ZIF-300,and most reported catalysts.This study offers a simple method of bifunctional SAC/MOF nanocomposite fabrication and usage,and provides guidance for the precise design of additional original SACs with unique catalytic properties.
基金supported in part by National Key Research and Development Program of China(2022YFA1004600)in part by the National Natural Science Foundation of China(51977166,52277123)in part by the Natural Science Foundation of Shaanxi Province(2022JC-19)。
文摘This paper proposes a voltage source converter (VSC) -based AC-DC hybrid distribution system (HDS) resilient model to mitigate power outages caused by wildfires. Before a wildfire happens, the public-safety power shutoff (PSPS) strategy is applied to actively cut some vulnerable lines which may easily cause wildfires, and reinforce some lines that are connected to critical loads. To mitigate load shedding caused by active line disconnection in the PSPS strategy, network reconfiguration is applied before the wildfire occurrence. During the restoration period, repair crews (RCs) repair faulted lines, and network reconfiguration is also taken into consideration in the recovery strategy to pick up critical loads. Since there exists possible errors in the wildfire prediction, several different scenarios of wildfire occurrence have been taken into consideration, leading to the proposition of a stochastic multi-period resilient model for the VSC-based AC-DC HDS. To accelerate the computational performance, a progressive hedging algorithm has been applied to solve the stochastic model which can be written as a mixed-integer linear program. The proposed model is verified on a 106-bus AC-DC HDS under wildfire conditions, and the result shows the proposed model not only can improve the system resilience but also accelerate computational speed.
基金supported by the National Key R&D Program of China(2022YFA1204000 to T.D.)the Guangdong Key Area Research and Development Program(2019B020228001 to T.D.)the National Natural Science Foundation of China(81971906 to T.D.).
文摘Nasopharyngeal carcinoma(NPC)is a malignancy originating from the nasopharyngeal epithelial cells.Although some studies have identified potential biomarkers for early diagnosis of NPC based on metabolomics data(Chen et al.,2023;Zhou et al.,2023)and Epstein-Barr virus subtypes(Xu et al.,2019),their effectiveness and applicability need further investigation,particularly when consideringthe roles of oral microbiota.
基金the financial support from the National Natural Science Foundation of China(Grant No.51178340)the Ministry of Education(No.NCET-06-0383).
文摘Large quantities of construction and demolition(C&D)building waste are being generated as a result of rapid urbanization and natural disasters in China.An increasing awareness of environmental protection is escalating C&D waste disposal concerns.This paper presents a brief introduction to current shaking table test research in China on structures built with recycled aggregate concrete(RAC).Test structures include a cast-in situ frame model,a precast frame model and a block masonry building.The test results prove that it is feasible to use RAC as a structural material in seismic areas,with recommended modifications and proper design,especially in low-rise structures.This paper also presents several successful applications of RAC in civil and structural engineering projects in China,which will serve to promote RAC as a global ecological structural material.
