This essay delves into the pivotal role of mathematics within the context of STEAM(science,technology,engineering,arts,and mathematics)education under China’s“Double Reduction”policy.Amidst a shifting global educat...This essay delves into the pivotal role of mathematics within the context of STEAM(science,technology,engineering,arts,and mathematics)education under China’s“Double Reduction”policy.Amidst a shifting global education landscape that emphasizes holistic growth,policies such as the“Double Reduction”strategy underscore the significance of well-rounded development alongside academic excellence.By advocating for a balanced approach to education,the policy resonates with the principles of STEAM education,which seeks to cultivate versatile and innovative individuals.Mathematics,acting as a unifying force,connects disparate STEAM disciplines,fostering interdisciplinary collaboration and preparing students to thrive in a rapidly evolving,technology-driven world.This essay provides an in-depth exploration of the multifaceted role of mathematics in STEAM education,drawing on specific cases and scholarly references to highlight its contributions to creativity,critical thinking,and holistic development.展开更多
Under China’s“Double Reduction”policy,although the educational pressure has somewhat reduced,the mechanism of talent selection through examinations still exists,which means competition remains,leading to the intern...Under China’s“Double Reduction”policy,although the educational pressure has somewhat reduced,the mechanism of talent selection through examinations still exists,which means competition remains,leading to the internalization of education.This article analyzes the challenges faced by the“Double Reduction”policy from historical and current perspectives.The reasons for the internalization of education are examined and four recommendations for the further implementation of the“Double Reduction”policy are presented.展开更多
The “Double Reduction” policy is not only to reduce the excessive learning burden of students, but also to improve the quality of students’ learning and to promote their overall development. In order to achieve the...The “Double Reduction” policy is not only to reduce the excessive learning burden of students, but also to improve the quality of students’ learning and to promote their overall development. In order to achieve the goal of the “Double Reduction” policy, it is necessary to focus on the implementation of measures to strengthen process evaluation as proposed in the “General Plan for Deepening Education Evaluation Reform in a New Era”. Therefore, the article will analyze the current situation of the research from three aspects: the connotation of “Double Reduction” and process evaluation, process evaluation under “Double Reduction” and process evaluation in English teaching, and look forward to the future development trend, with the aim of implementing the “Double Reduction” policy and giving full play to process evaluation. The aim is to implement the policy of “Double Reduction” and give full play to the role of process evaluation, so as to effectively guide the practice of English teaching.展开更多
Recently,the Chinese government has published a new policy,called“Double Reduction”,addressing the problems of the workloads of the students under high school,and in the after-school training institution.Under this ...Recently,the Chinese government has published a new policy,called“Double Reduction”,addressing the problems of the workloads of the students under high school,and in the after-school training institution.Under this current situation,many after-school training institutions are confronting serious difficulties,even have to shut down and exit the market.Thus,it is of great significance to carefully analyze and discuss the influence on a certain case and its countermeasures.The article discusses the background of the“Double Reduction”policy,which is exam-oriented education,quality-oriented education,and education modernization.The article analyzes the influence and countermeasures of the“Double Reduction”on a medium size after-school English training institution in Wenzhou,Zhejiang,China.By using the method of interview,this article presents specific data about the influence and detailed plans of transition.展开更多
Based on Cognitive Style Theory,Oxford’s Speaking Learning Theory and Communicative Competence Theory,this paper adopts questionnaire method,uses Sternberg’s Thinking Style Inventory modified by Zhang Lifang,as well...Based on Cognitive Style Theory,Oxford’s Speaking Learning Theory and Communicative Competence Theory,this paper adopts questionnaire method,uses Sternberg’s Thinking Style Inventory modified by Zhang Lifang,as well as Oxford’s Learning Strategies Scale,and combines with the actual situation of junior high school students’oral learning to design the questionnaire of speaking learning strategies.Eighth graders of a junior middle school in Sichuan Province are randomly selected as the research object.The statistical tool SPSS23.0 is used to conduct the descriptive analysis and Pearson correlation analysis of the questionnaire results to explore the overall situation of junior high school students’thinking styles and the use of English-speaking learning strategies as well as their correlation.According to the research,junior high school students generally tend to executive style,liberal style,conservative style,legislative style,hierarchic style.The use of speaking learning strategies is at an average level.They tend to use memory speaking strategies,social speaking strategies,affective speaking strategies,and cognitive speaking strategies.As a whole,there is a relatively significant correlation between thinking styles and speaking learning strategies.Specifically,there is a partial correlation between thinking styles and speaking learning strategies.展开更多
The calculation of the factor of safety(FOS)is an important means of slope evaluation.This paper proposed an improved double strength reductionmethod(DRM)to analyze the safety of layered slopes.The physical properties...The calculation of the factor of safety(FOS)is an important means of slope evaluation.This paper proposed an improved double strength reductionmethod(DRM)to analyze the safety of layered slopes.The physical properties of different soil layers of the slopes are different,so the single coefficient strength reduction method(SRM)is not enough to reflect the actual critical state of the slopes.Considering that the water content of the soil in the natural state is the main factor for the strength of the soil,the attenuation law of shear strength of clayey soil changing with water content is fitted.This paper also establishes the functional relationship between different reduction coefficients.Then,a USDFLD subroutine is programmed using the secondary development function of finite element software.Controlling the relationship between field variables and calculation time realizes double strength reduction applicable to the layered slope.Finally,by comparing the calculation results of different examples,it is proved that the stress and displacement distribution of the critical slope state obtained by the improved method is more realistic,and the calculated safety factor is more reliable.The newly proposedmethod considers the difference of intensity attenuation between different soil layers under natural conditions and avoids the disadvantage of the strength reduction method with uniform parameters,which provides a new idea and method for stability analysis of layered and complex slopes.展开更多
Reduction of the radar cross-section(RCS) is the key to stealth technology. To improve the RCS reduction effect of the designed checkerboard metasurface and overcome the limitation of thinlayer plasma in RCS reduction...Reduction of the radar cross-section(RCS) is the key to stealth technology. To improve the RCS reduction effect of the designed checkerboard metasurface and overcome the limitation of thinlayer plasma in RCS reduction technology, a double-layer-plasma-based metasurface—composed of a checkerboard metasurface, a double-layer plasma and an air gap between them—was investigated. Based on the principle of backscattering cancellation, we designed a checkerboard metasurface composed of different artificial magnetic conductor units;the checkerboard metasurface can reflect vertically incident electromagnetic(EM) waves in four different inclined directions to reduce the RCS. Full-wave simulations confirm that the doublelayer-plasma-based metasurface can improve the RCS reduction effect of the metasurface and the plasma. This is because in a band lower than the working band of the metasurface, the RCS reduction effect is mainly improved by the plasma layer. In the working band of the metasurface,impedance mismatching between the air gap and first plasma layer and between first and second plasma layers cause the scattered waves to become more dispersed, so the propagation path of the EM waves in the plasma becomes longer, increasing the absorption of the EM waves by the plasma. Thus, the RCS reduction effect is enhanced. The double-layer-plasma-based metasurface can be insensitive to the polarization of the incoming EM waves, and can also maintain a satisfactory RCS reduction band when the incident waves are oblique.展开更多
The rational design of a novel catalytic center with a sound basis remains both challenging and rewarding for the electrochemical reduction of N2(e NRR),which has provided a feasible route for achieving clean and sust...The rational design of a novel catalytic center with a sound basis remains both challenging and rewarding for the electrochemical reduction of N2(e NRR),which has provided a feasible route for achieving clean and sustainable NH3production under ambient conditions.Herein,using density functional theory calculations,we demonstrate that hybrid metal(M)-boron(B)double-atom catalysts(DACs)embedded in gC_(2)N substrate(M-B@C_(2)N,M=3d,4d and 5d transition metals)can achieve both high catalytic activity and high selectivity in e NRR.The proposed M-B@C_(2)N DACs have exhibited impressive feasibility and stability thanks to the resilient and robust C_(2)N substrate with abundant pyridinic N atoms distributed among right-sized pore structures.Our results reveal that like the metal center,the embedded B atom can actively involve in N≡N bond activation viaπ*-backdonation mechanism concomitant with the substantial charge transfer to adsorbed*N2,leading to sizable NAN bond elongation.Accordingly,both adsorption energy and NAN bond length of*N2can be employed as catalytic descriptors for predicting e NRR activity in terms of the limiting potentials(UL).Using high-throughput screening method,we found that six M-B@C_(2)N candidates have stood out as the outstanding electrocatalysts for driving e NRR,namely,M=Ti(UL=0 V),Mo(UL=0 V),Nb(UL=-0.04 V),W(UL=-0.23 V),Zr(UL=-0.26 V),V(UL=-0.28 V).The underlying origin is attributed to the balanced and constrained N-affinity of M-B dual site working in synergy,which can thus be used as one important guide of catalyst design.展开更多
Bimetallic compounds such as hydrotalcite-type layered double hydroxides(LDHs)are promising electrocatalysts owing to their unique electronic structures.However,their abilities toward nitrogen adsorption and reduction...Bimetallic compounds such as hydrotalcite-type layered double hydroxides(LDHs)are promising electrocatalysts owing to their unique electronic structures.However,their abilities toward nitrogen adsorption and reduction are undermined since the surface-mantled,electronegative-OH groups hinder the charge transfer between transition metal atoms and nitrogen molecules.Herein,a smart interfacing strategy is proposed to construct a coupled heterointerface between LDH and 2D g-C_(3)N_(4),which is proven by density functional theory(DFT)investigations to be favorable for nitrogen adsorption and ammonia desorption compared with neat LDH surface.The interfaced LDH and g-C_(3)N_(4) is further hybridized with a self-standing TiO_(2) nanofibrous membrane(NM)to maximize the interfacial effect owing to its high porosity and large surface area.Profited from the synergistic superiorities of the three components,the LDH@C_(3)N_(4)@TiO_(2) NM delivers superior ammonia yield(2.07×10^(−9) mol s^(−1) cm^(−2))and Faradaic efficiency(25.3%),making it a high-efficiency,noble-metal-free catalyst system toward electrocatalytic nitrogen reduction.展开更多
Increasing the efficiency and proportion of photovoltaic power generation installations is one of the best ways to reduce both CO_(2) emissions and reliance on fossil-fuel-based power supplies.Solar energy is a clean ...Increasing the efficiency and proportion of photovoltaic power generation installations is one of the best ways to reduce both CO_(2) emissions and reliance on fossil-fuel-based power supplies.Solar energy is a clean and renewable power source with excellent potential for further development and utilization.In 2021,the global solar installed capacity was about 749.7 GW.Establishing correlations between solar power generation,standard coal equivalent,carbon sinks,and green sinks is crucial.However,there have been few reports about correlations between the efficiency of tracking solar photovoltaic panels and the above parameters.This paper calculates the increased power generation achievable through the use of tracking photovoltaic panels compared with traditional fixed panels and establishes relationships between power generation,standard coal equivalent,and carbon sinks,providing a basis for attempts to reduce reliance on carbon-based fuels.The calculations show that power generation efficiency can be improved by about 26.12%by enabling solar panels to track the sun's rays during the day and from season to season.Through the use of this improved technology,global CO_(2) emissions can be reduced by 183.63 Mt,and the standard coal equivalent can be reduced by 73.67 Mt yearly.Carbon capture is worth approximately EUR 15.48 billion,and carbon accounting analysis plays a vital role in carbon trading.展开更多
The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and...The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and homonuclear double-atom catalysts have been preliminarily explored,but the relationship between the inherent properties and catalytic activity of heteronuclear double-atom catalysts with better performance remains unclear.Therefore,it is very significant to explore the prediction expressions of catalytic activity of heteronuclear double-atom catalysts based on their inherent properties and find the rule for selecting catalytic centers.Herein,by summarizing the free energy for the key steps of NRR on 55 catalysts calculated through the first-principle,the expressions of predicting the free energy and the corresponding descriptors are deduced by the machine learning,and the strategy for selecting the appropriate catalytic center is proposed.The selection strategy for the central atom of heteronuclear double-atom catalysts is that the atomic number of central B atom should be between group VB and VIIIB,and the electron difference between central A atom and B atom should be large enough,and the selectivity of NRR or hydrogen evolution reaction(HER)could be calculated through the prediction formula.Moreover,five catalysts are screened to have low limiting potential and excellent selectivity,and are further analyzed by electron transfer.This work explores the relationship between the inherent properties of heteronuclear double-atom catalysts and the catalytic activity,and puts forward the rules for selecting the heteronuclear double-atom catalytic center,which has guiding significance for the experiment.展开更多
Chinese education is like a large competitive game in the past time,with a lot of over-step learning and pre-emptive education increasing the extra—curricular pressure on primary and secondary school students day by ...Chinese education is like a large competitive game in the past time,with a lot of over-step learning and pre-emptive education increasing the extra—curricular pressure on primary and secondary school students day by day.In 2021,the national"double reduction"policy was implemented,and in 2022,the"Family Education Promotion Law of the People's Republic of China"was introduced.With the combined effect of"one government,one law",the status and role of family education have become more prominent,so it is of great practical significance to understand the education investment behavior of Chinese families.Therefore,this study is a case study of three students and their families from different schools in Weifang,Shandong Province in China.Through semi-structured interviews,this paper discusses the educational investment of well-off families after the implementation of the double reduction policy.The results show that art-related learning content dominates the education expenditure of well-off families after the implementation of the double-reducing policy,while cultural tutoring decreases.Becasue of(a)parents mainly want to cultivate their children's interests and hobbies or provide guidance for weak subjects;(b)the lack of understanding of the double reduction policy,leading to parents and students blindly follow the trend,increasing the pressure of students and parents'anxiety.This study focuses on the feelings of students and parents after the implementation of the double reduction policy,and attaches importance to the problems arising after the implementation of the policy.The findings are helpful to provide reference for future research on the educational investment of wealthy families after the implementation of the double reduction policy.展开更多
The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-b...The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was investigated.Initially,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping content.With an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped nanoparticles.Furthermore,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR cell.While the ECR activity increased after a small amount of N doping,it decreased for higher N doping content.Among them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V vs.reversible hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.展开更多
Joint time–frequency analysis is an emerging method for interpreting the underlying physics in fuel cells,batteries,and supercapacitors.To increase the reliability of time–frequency analysis,a theoretical correlatio...Joint time–frequency analysis is an emerging method for interpreting the underlying physics in fuel cells,batteries,and supercapacitors.To increase the reliability of time–frequency analysis,a theoretical correlation between frequency-domain stationary analysis and time-domain transient analysis is urgently required.The present work formularizes a thorough model reduction of fractional impedance spectra for electrochemical energy devices involving not only the model reduction from fractional-order models to integer-order models and from high-to low-order RC circuits but also insight into the evolution of the characteristic time constants during the whole reduction process.The following work has been carried out:(i)the model-reduction theory is addressed for typical Warburg elements and RC circuits based on the continued fraction expansion theory and the response error minimization technique,respectively;(ii)the order effect on the model reduction of typical Warburg elements is quantitatively evaluated by time–frequency analysis;(iii)the results of time–frequency analysis are confirmed to be useful to determine the reduction order in terms of the kinetic information needed to be captured;and(iv)the results of time–frequency analysis are validated for the model reduction of fractional impedance spectra for lithium-ion batteries,supercapacitors,and solid oxide fuel cells.In turn,the numerical validation has demonstrated the powerful function of the joint time–frequency analysis.The thorough model reduction of fractional impedance spectra addressed in the present work not only clarifies the relationship between time-domain transient analysis and frequency-domain stationary analysis but also enhances the reliability of the joint time–frequency analysis for electrochemical energy devices.展开更多
Lithium recovery from spent lithium-ion batteries(LIBs)have attracted extensive attention due to the skyrocketing price of lithium.The medium-temperature carbon reduction roasting was proposed to preferential selectiv...Lithium recovery from spent lithium-ion batteries(LIBs)have attracted extensive attention due to the skyrocketing price of lithium.The medium-temperature carbon reduction roasting was proposed to preferential selective extraction of lithium from spent Li-CoO_(2)(LCO)cathodes to overcome the incomplete recovery and loss of lithium during the recycling process.The LCO layered structure was destroyed and lithium was completely converted into water-soluble Li2CO_(3)under a suitable temperature to control the reduced state of the cobalt oxide.The Co metal agglomerates generated during medium-temperature carbon reduction roasting were broken by wet grinding and ultrasonic crushing to release the entrained lithium.The results showed that 99.10%of the whole lithium could be recovered as Li2CO_(3)with a purity of 99.55%.This work provided a new perspective on the preferentially selective extraction of lithium from spent lithium batteries.展开更多
Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the...Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the conventional Haber–Bosch process that operates under harsh conditions,which consumes large quantities of fossil fuels and releases a large amount of carbon dioxide.As an alternative,electrosynthesis is a prospective method for producing NH_(3)under normal temperature and pressure conditions.Although electrocatalytic nitrogen reduction to ammonia has attracted considerable attentions,the low solubility of N_(2)and high N≡N cracking energy render the achievements of high NH_(3) yield rate and Faradaic efficiency difficult.Nitrate and nitrite(NO_(x)^(-))are common N-containing pollutants.Due to their high solubilities and low dissociation energy of N=O,NO_(x)^(-)−are ideal raw materials for NH_(3) production.Therefore,electrocatalytic NO_(x)^(-)−reduction to NH_(3)(eNO_(x)RR)is a prospective strategy to simultaneously realise environmental protection and NH_(3) synthesis.This review offers a comprehensive understanding of the thriving eNO_(x)RR under ambient conditions.At first,the popular theory and mechanism of eNO_(x)RR and a summary of the measurement system and evaluation criteria are introduced.Thereafter,various strategies for developing NO_(x)−reduction catalysts are systematically presented and discussed.Finally,the challenges and possible prospects of electrocatalytic NO_(x)^(-1) reduction are outlined to facilitate energy-saving and environmentally friendly large-scale synthesis of NH_(3) in the future.展开更多
We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on t...We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on thepoint-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peakcompression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metalmicrowire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamicsimulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, arealdensities of the targets were evaluated.展开更多
Carbon dioxide conversion into valuable products using photocatalysis and electrocatalysis is an effective approach to mitigate global environmental issues and the energy shortages. Among the materials utilized for ca...Carbon dioxide conversion into valuable products using photocatalysis and electrocatalysis is an effective approach to mitigate global environmental issues and the energy shortages. Among the materials utilized for catalytic reduction of CO_(2), Cu-based materials are highly advantageous owing to their widespread availability, cost-effectiveness, and environmental sustainability. Furthermore, Cu-based materials demonstrate interesting abilities in the adsorption and activation of carbon dioxide, allowing the formation of C_(2+) compounds through C–C coupling process. Herein, the basic principles of photocatalytic CO_(2) reduction reactions(PCO_(2)RR) and electrocatalytic CO_(2) reduction reaction(ECO_(2)RR) and the pathways for the generation C_(2+) products are introduced. This review categorizes Cu-based materials into different groups including Cu metal, Cu oxides, Cu alloys, and Cu SACs, Cu heterojunctions based on their catalytic applications. The relationship between the Cu surfaces and their efficiency in both PCO_(2)RR and ECO_(2)RR is emphasized. Through a review of recent studies on PCO_(2)RR and ECO_(2)RR using Cu-based catalysts, the focus is on understanding the underlying reasons for the enhanced selectivity toward C_(2+) products. Finally, the opportunities and challenges associated with Cu-based materials in the CO_(2) catalytic reduction applications are presented, along with research directions that can guide for the design of highly active and selective Cu-based materials for CO_(2) reduction processes in the future.展开更多
文摘This essay delves into the pivotal role of mathematics within the context of STEAM(science,technology,engineering,arts,and mathematics)education under China’s“Double Reduction”policy.Amidst a shifting global education landscape that emphasizes holistic growth,policies such as the“Double Reduction”strategy underscore the significance of well-rounded development alongside academic excellence.By advocating for a balanced approach to education,the policy resonates with the principles of STEAM education,which seeks to cultivate versatile and innovative individuals.Mathematics,acting as a unifying force,connects disparate STEAM disciplines,fostering interdisciplinary collaboration and preparing students to thrive in a rapidly evolving,technology-driven world.This essay provides an in-depth exploration of the multifaceted role of mathematics in STEAM education,drawing on specific cases and scholarly references to highlight its contributions to creativity,critical thinking,and holistic development.
文摘Under China’s“Double Reduction”policy,although the educational pressure has somewhat reduced,the mechanism of talent selection through examinations still exists,which means competition remains,leading to the internalization of education.This article analyzes the challenges faced by the“Double Reduction”policy from historical and current perspectives.The reasons for the internalization of education are examined and four recommendations for the further implementation of the“Double Reduction”policy are presented.
文摘The “Double Reduction” policy is not only to reduce the excessive learning burden of students, but also to improve the quality of students’ learning and to promote their overall development. In order to achieve the goal of the “Double Reduction” policy, it is necessary to focus on the implementation of measures to strengthen process evaluation as proposed in the “General Plan for Deepening Education Evaluation Reform in a New Era”. Therefore, the article will analyze the current situation of the research from three aspects: the connotation of “Double Reduction” and process evaluation, process evaluation under “Double Reduction” and process evaluation in English teaching, and look forward to the future development trend, with the aim of implementing the “Double Reduction” policy and giving full play to process evaluation. The aim is to implement the policy of “Double Reduction” and give full play to the role of process evaluation, so as to effectively guide the practice of English teaching.
文摘Recently,the Chinese government has published a new policy,called“Double Reduction”,addressing the problems of the workloads of the students under high school,and in the after-school training institution.Under this current situation,many after-school training institutions are confronting serious difficulties,even have to shut down and exit the market.Thus,it is of great significance to carefully analyze and discuss the influence on a certain case and its countermeasures.The article discusses the background of the“Double Reduction”policy,which is exam-oriented education,quality-oriented education,and education modernization.The article analyzes the influence and countermeasures of the“Double Reduction”on a medium size after-school English training institution in Wenzhou,Zhejiang,China.By using the method of interview,this article presents specific data about the influence and detailed plans of transition.
文摘Based on Cognitive Style Theory,Oxford’s Speaking Learning Theory and Communicative Competence Theory,this paper adopts questionnaire method,uses Sternberg’s Thinking Style Inventory modified by Zhang Lifang,as well as Oxford’s Learning Strategies Scale,and combines with the actual situation of junior high school students’oral learning to design the questionnaire of speaking learning strategies.Eighth graders of a junior middle school in Sichuan Province are randomly selected as the research object.The statistical tool SPSS23.0 is used to conduct the descriptive analysis and Pearson correlation analysis of the questionnaire results to explore the overall situation of junior high school students’thinking styles and the use of English-speaking learning strategies as well as their correlation.According to the research,junior high school students generally tend to executive style,liberal style,conservative style,legislative style,hierarchic style.The use of speaking learning strategies is at an average level.They tend to use memory speaking strategies,social speaking strategies,affective speaking strategies,and cognitive speaking strategies.As a whole,there is a relatively significant correlation between thinking styles and speaking learning strategies.Specifically,there is a partial correlation between thinking styles and speaking learning strategies.
基金This research was funded by the National Natural Science Foundation of China(51709194),Qinglan Project of Jiangsu University,the Priority Academic Program Development of Jiangsu Higher Education Institutions,and Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering.
文摘The calculation of the factor of safety(FOS)is an important means of slope evaluation.This paper proposed an improved double strength reductionmethod(DRM)to analyze the safety of layered slopes.The physical properties of different soil layers of the slopes are different,so the single coefficient strength reduction method(SRM)is not enough to reflect the actual critical state of the slopes.Considering that the water content of the soil in the natural state is the main factor for the strength of the soil,the attenuation law of shear strength of clayey soil changing with water content is fitted.This paper also establishes the functional relationship between different reduction coefficients.Then,a USDFLD subroutine is programmed using the secondary development function of finite element software.Controlling the relationship between field variables and calculation time realizes double strength reduction applicable to the layered slope.Finally,by comparing the calculation results of different examples,it is proved that the stress and displacement distribution of the critical slope state obtained by the improved method is more realistic,and the calculated safety factor is more reliable.The newly proposedmethod considers the difference of intensity attenuation between different soil layers under natural conditions and avoids the disadvantage of the strength reduction method with uniform parameters,which provides a new idea and method for stability analysis of layered and complex slopes.
基金supported in part by the China Postdoctoral Science Foundation (No. 2020M673341)in part by the Natural Science Basic Research Program of Shaanxi (No.2023-JC-YB-549)+1 种基金in part by National Natural Science Foundation of China (Nos. 62371375 and 62371372)Innovation Capability Support Program of Shaanxi (No. 2022TD-37)。
文摘Reduction of the radar cross-section(RCS) is the key to stealth technology. To improve the RCS reduction effect of the designed checkerboard metasurface and overcome the limitation of thinlayer plasma in RCS reduction technology, a double-layer-plasma-based metasurface—composed of a checkerboard metasurface, a double-layer plasma and an air gap between them—was investigated. Based on the principle of backscattering cancellation, we designed a checkerboard metasurface composed of different artificial magnetic conductor units;the checkerboard metasurface can reflect vertically incident electromagnetic(EM) waves in four different inclined directions to reduce the RCS. Full-wave simulations confirm that the doublelayer-plasma-based metasurface can improve the RCS reduction effect of the metasurface and the plasma. This is because in a band lower than the working band of the metasurface, the RCS reduction effect is mainly improved by the plasma layer. In the working band of the metasurface,impedance mismatching between the air gap and first plasma layer and between first and second plasma layers cause the scattered waves to become more dispersed, so the propagation path of the EM waves in the plasma becomes longer, increasing the absorption of the EM waves by the plasma. Thus, the RCS reduction effect is enhanced. The double-layer-plasma-based metasurface can be insensitive to the polarization of the incoming EM waves, and can also maintain a satisfactory RCS reduction band when the incident waves are oblique.
基金supported by the National Natural Science Foundation of China(21673137)the support from the Program for Top Talents in Songjiang District of Shanghai。
文摘The rational design of a novel catalytic center with a sound basis remains both challenging and rewarding for the electrochemical reduction of N2(e NRR),which has provided a feasible route for achieving clean and sustainable NH3production under ambient conditions.Herein,using density functional theory calculations,we demonstrate that hybrid metal(M)-boron(B)double-atom catalysts(DACs)embedded in gC_(2)N substrate(M-B@C_(2)N,M=3d,4d and 5d transition metals)can achieve both high catalytic activity and high selectivity in e NRR.The proposed M-B@C_(2)N DACs have exhibited impressive feasibility and stability thanks to the resilient and robust C_(2)N substrate with abundant pyridinic N atoms distributed among right-sized pore structures.Our results reveal that like the metal center,the embedded B atom can actively involve in N≡N bond activation viaπ*-backdonation mechanism concomitant with the substantial charge transfer to adsorbed*N2,leading to sizable NAN bond elongation.Accordingly,both adsorption energy and NAN bond length of*N2can be employed as catalytic descriptors for predicting e NRR activity in terms of the limiting potentials(UL).Using high-throughput screening method,we found that six M-B@C_(2)N candidates have stood out as the outstanding electrocatalysts for driving e NRR,namely,M=Ti(UL=0 V),Mo(UL=0 V),Nb(UL=-0.04 V),W(UL=-0.23 V),Zr(UL=-0.26 V),V(UL=-0.28 V).The underlying origin is attributed to the balanced and constrained N-affinity of M-B dual site working in synergy,which can thus be used as one important guide of catalyst design.
基金financially supported by the National Natural Science Foundation of China(No.52173055 and 21961132024)the Natural Science Foundation of Shanghai(No.19ZR1401100)+3 种基金the International Cooperation Fund of Science and Technology Commission of Shanghai Municipality(No.21130750100)the Innovation Program of Shanghai Municipal Education Commission(No.2017-01-07-00-03-E00024)the Fundamental Research Funds for the Central Universities(No.18D310109)the DHU Distinguished Young Professor Program(No.LZA2020001).
文摘Bimetallic compounds such as hydrotalcite-type layered double hydroxides(LDHs)are promising electrocatalysts owing to their unique electronic structures.However,their abilities toward nitrogen adsorption and reduction are undermined since the surface-mantled,electronegative-OH groups hinder the charge transfer between transition metal atoms and nitrogen molecules.Herein,a smart interfacing strategy is proposed to construct a coupled heterointerface between LDH and 2D g-C_(3)N_(4),which is proven by density functional theory(DFT)investigations to be favorable for nitrogen adsorption and ammonia desorption compared with neat LDH surface.The interfaced LDH and g-C_(3)N_(4) is further hybridized with a self-standing TiO_(2) nanofibrous membrane(NM)to maximize the interfacial effect owing to its high porosity and large surface area.Profited from the synergistic superiorities of the three components,the LDH@C_(3)N_(4)@TiO_(2) NM delivers superior ammonia yield(2.07×10^(−9) mol s^(−1) cm^(−2))and Faradaic efficiency(25.3%),making it a high-efficiency,noble-metal-free catalyst system toward electrocatalytic nitrogen reduction.
文摘Increasing the efficiency and proportion of photovoltaic power generation installations is one of the best ways to reduce both CO_(2) emissions and reliance on fossil-fuel-based power supplies.Solar energy is a clean and renewable power source with excellent potential for further development and utilization.In 2021,the global solar installed capacity was about 749.7 GW.Establishing correlations between solar power generation,standard coal equivalent,carbon sinks,and green sinks is crucial.However,there have been few reports about correlations between the efficiency of tracking solar photovoltaic panels and the above parameters.This paper calculates the increased power generation achievable through the use of tracking photovoltaic panels compared with traditional fixed panels and establishes relationships between power generation,standard coal equivalent,and carbon sinks,providing a basis for attempts to reduce reliance on carbon-based fuels.The calculations show that power generation efficiency can be improved by about 26.12%by enabling solar panels to track the sun's rays during the day and from season to season.Through the use of this improved technology,global CO_(2) emissions can be reduced by 183.63 Mt,and the standard coal equivalent can be reduced by 73.67 Mt yearly.Carbon capture is worth approximately EUR 15.48 billion,and carbon accounting analysis plays a vital role in carbon trading.
基金supports by the National Natural Science Foundation of China(NSFC,52271113)the Natural Science Foundation of Shaanxi Province,China(2020JM 218)+1 种基金the Fundamental Research Funds for the Central Universities(CHD300102311405)HPC platform,Xi’an Jiaotong University。
文摘The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and homonuclear double-atom catalysts have been preliminarily explored,but the relationship between the inherent properties and catalytic activity of heteronuclear double-atom catalysts with better performance remains unclear.Therefore,it is very significant to explore the prediction expressions of catalytic activity of heteronuclear double-atom catalysts based on their inherent properties and find the rule for selecting catalytic centers.Herein,by summarizing the free energy for the key steps of NRR on 55 catalysts calculated through the first-principle,the expressions of predicting the free energy and the corresponding descriptors are deduced by the machine learning,and the strategy for selecting the appropriate catalytic center is proposed.The selection strategy for the central atom of heteronuclear double-atom catalysts is that the atomic number of central B atom should be between group VB and VIIIB,and the electron difference between central A atom and B atom should be large enough,and the selectivity of NRR or hydrogen evolution reaction(HER)could be calculated through the prediction formula.Moreover,five catalysts are screened to have low limiting potential and excellent selectivity,and are further analyzed by electron transfer.This work explores the relationship between the inherent properties of heteronuclear double-atom catalysts and the catalytic activity,and puts forward the rules for selecting the heteronuclear double-atom catalytic center,which has guiding significance for the experiment.
基金This paper is supported by the Macao Foundation's research project"An Empirical Study on the Training Standards for Innovative Talents in the Guangdong-Hong Kong-Macao Greater Bay Area"(MF2315)and the 2021 General Project of the 14th Five-Year Plan of Philosophy and Social Sciences of Guangdong Province of China(Number:GD21CJY08).
文摘Chinese education is like a large competitive game in the past time,with a lot of over-step learning and pre-emptive education increasing the extra—curricular pressure on primary and secondary school students day by day.In 2021,the national"double reduction"policy was implemented,and in 2022,the"Family Education Promotion Law of the People's Republic of China"was introduced.With the combined effect of"one government,one law",the status and role of family education have become more prominent,so it is of great practical significance to understand the education investment behavior of Chinese families.Therefore,this study is a case study of three students and their families from different schools in Weifang,Shandong Province in China.Through semi-structured interviews,this paper discusses the educational investment of well-off families after the implementation of the double reduction policy.The results show that art-related learning content dominates the education expenditure of well-off families after the implementation of the double-reducing policy,while cultural tutoring decreases.Becasue of(a)parents mainly want to cultivate their children's interests and hobbies or provide guidance for weak subjects;(b)the lack of understanding of the double reduction policy,leading to parents and students blindly follow the trend,increasing the pressure of students and parents'anxiety.This study focuses on the feelings of students and parents after the implementation of the double reduction policy,and attaches importance to the problems arising after the implementation of the policy.The findings are helpful to provide reference for future research on the educational investment of wealthy families after the implementation of the double reduction policy.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) (Grant Nos.2018R1A6A1A03024334,2019R1A2C1007637,2021M3I3A1082880,2021R1I1A1A01044174)the Basic Science Research Capacity Enhancement Project through Korea Basic Science Institute (Grant No.2019R1A6C1010024)。
文摘The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was investigated.Initially,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping content.With an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped nanoparticles.Furthermore,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR cell.While the ECR activity increased after a small amount of N doping,it decreased for higher N doping content.Among them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V vs.reversible hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.
基金support from the National Science Foundation of China(22078190)the National Key R&D Plan of China(2020YFB1505802).
文摘Joint time–frequency analysis is an emerging method for interpreting the underlying physics in fuel cells,batteries,and supercapacitors.To increase the reliability of time–frequency analysis,a theoretical correlation between frequency-domain stationary analysis and time-domain transient analysis is urgently required.The present work formularizes a thorough model reduction of fractional impedance spectra for electrochemical energy devices involving not only the model reduction from fractional-order models to integer-order models and from high-to low-order RC circuits but also insight into the evolution of the characteristic time constants during the whole reduction process.The following work has been carried out:(i)the model-reduction theory is addressed for typical Warburg elements and RC circuits based on the continued fraction expansion theory and the response error minimization technique,respectively;(ii)the order effect on the model reduction of typical Warburg elements is quantitatively evaluated by time–frequency analysis;(iii)the results of time–frequency analysis are confirmed to be useful to determine the reduction order in terms of the kinetic information needed to be captured;and(iv)the results of time–frequency analysis are validated for the model reduction of fractional impedance spectra for lithium-ion batteries,supercapacitors,and solid oxide fuel cells.In turn,the numerical validation has demonstrated the powerful function of the joint time–frequency analysis.The thorough model reduction of fractional impedance spectra addressed in the present work not only clarifies the relationship between time-domain transient analysis and frequency-domain stationary analysis but also enhances the reliability of the joint time–frequency analysis for electrochemical energy devices.
基金the Science and Technology Key Project of Anhui Province,China(No.2022e03020004).
文摘Lithium recovery from spent lithium-ion batteries(LIBs)have attracted extensive attention due to the skyrocketing price of lithium.The medium-temperature carbon reduction roasting was proposed to preferential selective extraction of lithium from spent Li-CoO_(2)(LCO)cathodes to overcome the incomplete recovery and loss of lithium during the recycling process.The LCO layered structure was destroyed and lithium was completely converted into water-soluble Li2CO_(3)under a suitable temperature to control the reduced state of the cobalt oxide.The Co metal agglomerates generated during medium-temperature carbon reduction roasting were broken by wet grinding and ultrasonic crushing to release the entrained lithium.The results showed that 99.10%of the whole lithium could be recovered as Li2CO_(3)with a purity of 99.55%.This work provided a new perspective on the preferentially selective extraction of lithium from spent lithium batteries.
基金supported by the National Natural Science Foundation of China[Nos.U21A20332,52103226,52202275,52203314,and 12204253]the Distinguished Young Scholars Fund of Jiangsu Province[No.BK20220061]the Fellowship of China Postdoctoral Science Foundation[No.2021M702382]。
文摘Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the conventional Haber–Bosch process that operates under harsh conditions,which consumes large quantities of fossil fuels and releases a large amount of carbon dioxide.As an alternative,electrosynthesis is a prospective method for producing NH_(3)under normal temperature and pressure conditions.Although electrocatalytic nitrogen reduction to ammonia has attracted considerable attentions,the low solubility of N_(2)and high N≡N cracking energy render the achievements of high NH_(3) yield rate and Faradaic efficiency difficult.Nitrate and nitrite(NO_(x)^(-))are common N-containing pollutants.Due to their high solubilities and low dissociation energy of N=O,NO_(x)^(-)−are ideal raw materials for NH_(3) production.Therefore,electrocatalytic NO_(x)^(-)−reduction to NH_(3)(eNO_(x)RR)is a prospective strategy to simultaneously realise environmental protection and NH_(3) synthesis.This review offers a comprehensive understanding of the thriving eNO_(x)RR under ambient conditions.At first,the popular theory and mechanism of eNO_(x)RR and a summary of the measurement system and evaluation criteria are introduced.Thereafter,various strategies for developing NO_(x)−reduction catalysts are systematically presented and discussed.Finally,the challenges and possible prospects of electrocatalytic NO_(x)^(-1) reduction are outlined to facilitate energy-saving and environmentally friendly large-scale synthesis of NH_(3) in the future.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1603300 and 2022YFA1603200)the Science Challenge Project(Grant No.TZ2018005)in China+1 种基金the National Natural Science Foundation of China(Grant Nos.11805188 and 12175209)the Laser Fusion Research Center Funds for Young Talents(Grant No.RCFPD6-2022-1).
文摘We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on thepoint-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peakcompression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metalmicrowire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamicsimulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, arealdensities of the targets were evaluated.
基金supported by the National Natural Science Foundation of China (22178149)Jiangsu Distinguished Professor Program+4 种基金Natural Science Foundation of Jiangsu Province for Outstanding Youth Scientists (BK20211599)Key R and D Project of Zhenjiang City (CQ2022001)Scientific Research Startup Foundation of Jiangsu University (Nos. 202096 and 22JDG020)Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment of Fuzhou University (SKLPEE-KF202310)the Opening Project of Structural Optimization and Application of Functional Molecules Key Laboratory of Sichuan Province (2023GNFZ-01)。
文摘Carbon dioxide conversion into valuable products using photocatalysis and electrocatalysis is an effective approach to mitigate global environmental issues and the energy shortages. Among the materials utilized for catalytic reduction of CO_(2), Cu-based materials are highly advantageous owing to their widespread availability, cost-effectiveness, and environmental sustainability. Furthermore, Cu-based materials demonstrate interesting abilities in the adsorption and activation of carbon dioxide, allowing the formation of C_(2+) compounds through C–C coupling process. Herein, the basic principles of photocatalytic CO_(2) reduction reactions(PCO_(2)RR) and electrocatalytic CO_(2) reduction reaction(ECO_(2)RR) and the pathways for the generation C_(2+) products are introduced. This review categorizes Cu-based materials into different groups including Cu metal, Cu oxides, Cu alloys, and Cu SACs, Cu heterojunctions based on their catalytic applications. The relationship between the Cu surfaces and their efficiency in both PCO_(2)RR and ECO_(2)RR is emphasized. Through a review of recent studies on PCO_(2)RR and ECO_(2)RR using Cu-based catalysts, the focus is on understanding the underlying reasons for the enhanced selectivity toward C_(2+) products. Finally, the opportunities and challenges associated with Cu-based materials in the CO_(2) catalytic reduction applications are presented, along with research directions that can guide for the design of highly active and selective Cu-based materials for CO_(2) reduction processes in the future.