Soil microbial communities and grassland ecosystem processes are increasingly confronted with multiple global change factors(GCFs).There is still a lack of research on how these multiple GCFs interact and impact soil ...Soil microbial communities and grassland ecosystem processes are increasingly confronted with multiple global change factors(GCFs).There is still a lack of research on how these multiple GCFs interact and impact soil microbial communities and their functions.To address this gap,we conducted a simulation experiment to examine the individual and interactive effects of the four most critical and prevalent GCFs,elevated carbon dioxide concentration(eCO_(2)),elevated temperature(eT),decreased precipitation(dP),and elevated nitrogen(N)deposition(eN).This study focused on their effects on soil physicochemical properties,bacterial and fungal communities,and extracellular enzyme activities(EEAs)related to carbon(C),N,and phosphorus(P)cycles in a temperate grassland.Results showed that eCO_(2),eN,and dP tended to increase EEAs,while having neutral effects on microbial diversity and community composition.On the other hand,eT resulted in decreases in soil pH,total C,total N,EEAs,and microbial diversity,but increases in plant biomass,total P,microbial richness,and network complexity and stability.This shift in the nutrient limitation from P to N under warming conditions resulted in decoupling of nutrients.Neutral or slightly negative relationships were found between enzyme activities and microbial richness,diversity,and dominant species,and the responses of microbial communities and ecological functions were asynchronous under GCFs.Importantly,our results revealed significant higher-order interactions among GCFs and found that they had notable effects on soil physicochemical properties as well as on microbial communities and ecological functions.These findings provide valuable insights and suggestions for ecological adaptations to future global changes.展开更多
To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplin...To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplinary coupling pose significant challenges to mission design.This paper first investigates the typical design scheme of the airbag landing system for manned spacecrafts to obtain basic insight.A comprehensive review of the past research works on the airbag landing system is then carried out from three aspects:dynamic modeling,performance optimization,and experimental study.The airbag landing system for spacecraft is a rigid-flexible-gas coupling system,which can be modeled through multi-body dynamics or finite element method.Different venting structures and optimization methods are introduced to improve the cushioning performance.Experimental setups for drop test and airbag test are developed to verify the design feasibility.Finally,this paper proposes key issues in the dynamics analysis and design optimization of the airbag landing system for future study.展开更多
The electrocatalytic furfural oxidation reaction(FFOR)represents an economical and promising technology to replace conventional oxygen evolution reaction,enabling the co-production of high value chemicals and H_(2).Re...The electrocatalytic furfural oxidation reaction(FFOR)represents an economical and promising technology to replace conventional oxygen evolution reaction,enabling the co-production of high value chemicals and H_(2).Regulating the adsorption of furfural(FF)and OH^(-)species holds paramount importance in enhancing the overall performance.Herein,we have developed a unique CuO catalyst enriched with oxygen vacancies(O_(v)-CuO)resulting from the electrochemical reconstruction ofα-Cu_(2)S,which demonstrates exceptional FFOR performance,with a conversion of 95.3%,near-perfect selectivity and Faraday efficiency(FE)for furoic acid(FA)at 1.475 V vs.RHE.The study provides detailed comparison of the structural evolution of different sulfide precatalysts and their impact on FFOR.Furthermore,it delves into the structure-activity relationship through a combination of characterization and theoretical calculations.The O_(v)-CuO not only enhances OH^(-)adsorption,changes the rate-determining step,but also reduces the reaction energy barrier toward FFOR.Additionally,a much lower cell voltage is required to coproduce FA and hydrogen in the two-electrode co-electrolysis system.This work would provide valuable insights into the reaction mechanism of FFOR on Cu based catalysts and establish guidelines for designing defective electrocatalysts for biomass conversion.展开更多
Elastic strain constitutes a decisive factor in determining the recoverable deformability of thermoelectric materials.Plastic deformation for microstructure engineering has been demonstrated as a viable approach to en...Elastic strain constitutes a decisive factor in determining the recoverable deformability of thermoelectric materials.Plastic deformation for microstructure engineering has been demonstrated as a viable approach to enhance the elastic strain.However,this approach is highly dependent on the material's plasticity,which is rather limited by the rigidity for the majority of inorganic semiconducting thermoelectric materials.Thermocouple materials,as metallic thermoelectric materials,possess a favorable plasticity,motivating this work to focus on the elastic bendability of a metallic thermoelectric generator that is composed of K-type thermocouple components,namely p-type Ni_(90)Cr_(10) and n-type Ni_(95)Al_(2)Mn_(2)Si.The cold-rolling process enables a large elastic modulus and a high yield strength,thanks to the texturized direction along<111>,and dense dislocations and refined grains,respectively,eventually resulting in a 400%increase in the elastic strain.Such superior elasticity ensures the preservation of the initial transport properties for the rolled films even after being bent 100000 times within a radius of~8 mm.A power output of~414μW is achieved in a ten-leg flexible thermoelectric device,suggesting its substantial potential for powering wearable electronics.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
This study investigates the geological background of the August 7-8, 2010 Zhouqu debris flows in the northwestern Chinese province of Gansu, and possible future occurrence of such hazards in the peri-Tibetan Plateau (...This study investigates the geological background of the August 7-8, 2010 Zhouqu debris flows in the northwestern Chinese province of Gansu, and possible future occurrence of such hazards in the peri-Tibetan Plateau (TP) regions. Debris flows are a more predictable type of landslide because of its strong correlation with extreme precipitation. However, two factors affecting the frequency and magnitude of debris flows: very fine scale precipitation and degree of fracture of bedrock, both defy direct observations. Annual mean Net Primary production (NPP) is used as a surrogate for regional precipitation with patchiness filtered out, and gravity satellite measured regional mass changes as an indication of bedrock cracking, through the groundwater as the nexus.?The GRACE measurements indicate a region (to the north east of TP) of persistent mass gain (started well before the 2008 Wenchuan earthquake), likely due to increased groundwater percolation. While in the neighboring agricultural region further to the north east, there are signal of decreased fossil water reservoir. The imposed stress fields by large scale increase/decrease groundwater may contribute to future geological instability of this region. Zhouqu locates right on the saddle of the gravity field anomaly. The region surrounding the Bay of Bangle (to the southeast of TP) has a similar situation. To investigate future changes in extreme precipitation, the other key player for debris flows, the “pseudo-climate change” experiments of a weather model forced by climate model provided perturbations on the thermal fields are performed and endangered locations are identified. In the future warmer climate, extreme precipitation will be more severe and debris will be more frequent and severe.展开更多
Distance higher education is an important component of the Chinese higher education.How to enhance the quality of distance higher education is one of the key issues to be addressed in the research areas of distance ed...Distance higher education is an important component of the Chinese higher education.How to enhance the quality of distance higher education is one of the key issues to be addressed in the research areas of distance education and higher education.As a crucial step to quality improvement,the constitution of accreditation system in distance higher education balances the benefits of all parties involved.This paper explores the American accreditation system of higher education and distance education and concludes with suggestions for the constitution of the Chinese quality assurance system:1)establishing third-party institutions to share part of the government roles;2)constituting the accreditation system;3)setting up appropriate standards;4)publicizing results of quality assurance work;and 5)building internal quality assurance mechanism.This paper is aimed to provide some reference to the constitution of accreditation system of distance higher education in China,facilitate the solution of quality problems in distance education,and promote the continuous improvement and development of distance education in China.展开更多
Thermoelectric generators,with the unique ability to convert temperature gradients into electricity,have long been acknowledged as a sustainable technique for waste heat recovery.The remarkable advancements in both th...Thermoelectric generators,with the unique ability to convert temperature gradients into electricity,have long been acknowledged as a sustainable technique for waste heat recovery.The remarkable advancements in both thermoelectric materials and devices have substantially propelled the practical applications of thermoelectric generators.The capability of generating electricity through the temperature gradient between the human body and the ambient environment highlights the significant potential of flexible thermoelectric devices as self-powered energy sources for wearable electronics.However,this leaves a formidable challenge with respect to the bendability of the high-performance,yet inherently brittle,inorganic thermoelectric materials.The strategies of dislocationization and grain refinement have been reported to effectively enhance the elastic strain,thereby ensuring fully recoverable bendability for inorganic thermoelectric materials[1,2].This offers a versatile approach for enhancing the elastic bendability of inorganic thermoelectric generators.展开更多
Functionalities of materials tightly relate to the atomic and electronic structures,the coupling between which through lattice and charge gives birth to thermoelectricity,enabling a direct heat‐electricity conversion...Functionalities of materials tightly relate to the atomic and electronic structures,the coupling between which through lattice and charge gives birth to thermoelectricity,enabling a direct heat‐electricity conversion.Booming wearable electronics nowadays urgently demand thermoelectric film generators as self‐powered units using body and environment heats,of which highly recoverable deformability and power are the core challenges.This indicates the great importance of elasticity since a plastic deformation otherwise actuates lattice slips to unsecure both thermoelectricity and recoverability.It is illustrated in this work texturization and dislocations for enhancing elasticity in cold‐rolled constantan foils,a metal thermoelectric enabling one of the highest power outputs near room temperature for deformable wearables.The device can work in a purely elastic region,to secure orders of magnitude improvement in recoverable bendability with an extraordinary specific power density,at a bending radius down to 5mm fitting the curvature of an adult's little finger.This work delivers a strategy for bringing robust deformability to thermoelectricity for powering wearable electronics.展开更多
Renewable electricity-driven CO evolu-tion from CO_(2)offers a promising route for sustainable chemical production.Single-atom alloy(SAA)catalysts are emerging as promising candidates for electrochemical CO_(2)reducti...Renewable electricity-driven CO evolu-tion from CO_(2)offers a promising route for sustainable chemical production.Single-atom alloy(SAA)catalysts are emerging as promising candidates for electrochemical CO_(2)reduction.Howev-er,the dynamic nature of SAAs within their local microenvironment often com-plicates our understanding of the under-lying mechanisms that contribute to their enhanced performance.In this study,we introduce a single-atom Co-modified Au nanoparticle catalyst(Co_(1)O_(x)@Au)for the electrocatalytic re-duction of CO_(2)to CO.Using operando X-ray absorption spectroscopy(XAS),we observe the dynamic transformation of Co_(1)O_(x)@Au into a low-valence Co_(1)Au SAA,driven by the applied voltages.This behavior strengthens the atomic interaction between Au and Co,thus ensuring a reinforced adsorption of the crucial^(*)COOH intermediate,which is corroborated by operan-do synchrotron-radiation Fourier transform infrared spectroscopy(SR-FTIR).Furthermore,the strengthened Au-Co interaction facilitates the subsequent desorption of the^(*)CO interme-diate,allowing for efficient CO formation and release.These insights highlight the self-opti-mization behavior of SAAs towards improving CO_(2)reduction selectivity.展开更多
Hybrid perovskite possesses excellent photoelectric properties,including large light-absorption capacity and high carrier mobility,and is an ideal light-absorbing material for photoelectric devices.The grain size and ...Hybrid perovskite possesses excellent photoelectric properties,including large light-absorption capacity and high carrier mobility,and is an ideal light-absorbing material for photoelectric devices.The grain size and compactness of hybrid perovskite are key factors affecting the performance of photoelectric devices.The photocurrent and photoresponsivity of these devices are relatively low because of the rapidly recombined photoexcited electron-hole pairs in hybrid perovskite.Herein,we develop a facile two-step chemical vapor deposition(CVD)method to synthesize a high-quality van der Waals(vd Ws)MAPb I3/graphene heterostructure for high-performance image sensor.We introduced inorganic sources(PbI2)to vd Ws epitaxially grown Pb I2 film on a seamless graphene monolayer film template through CVD.Methylammonium iodide(MAI)was then reintroduced to prepare the vd Ws MAPb I3/graphene heterostructure.The MAPb I3 layer is composed of densely packed,large-size grains and displays a smooth surface.High photoresponsivity of 107A/W is achieved in the corresponding photodetector.Inspired by the human visual system,we designed a flexible photodetector array containing(24?24)pixels,achieving perfect image recognition and color discrimination.Our study may greatly facilitate the construction of high-performance optoelectronic devices in artificial retina,biomedical imaging,remote sensing,and optical communication.展开更多
Skin,the largest organ in the human body,is sensitive to external stimuli.In recent years,an increasing number of skin-inspired electronics,including wearable electronics,implantable electronics,and electronic skin,ha...Skin,the largest organ in the human body,is sensitive to external stimuli.In recent years,an increasing number of skin-inspired electronics,including wearable electronics,implantable electronics,and electronic skin,have been developed because of their broad applications in healthcare and robotics.Physical sensors are one of the key building blocks of skin-inspired electronics.Typical physical sensors include mechanical sensors,temperature sensors,humidity sensors,electrophysiological sensors,and so on.In this review,we systematically review the latest advances of skin-inspired mechanical sensors,temperature sensors,and humidity sensors.The working mechanisms,key materials,device structures,and performance of various physical sensors are summarized and discussed in detail.Their applications in health monitoring,human disease diagnosis and treatment,and intelligent robots are reviewed.In addition,several novel properties of skin-inspired physical sensors such as versatility,self-healability,and implantability are introduced.Finally,the existing challenges and future perspectives of physical sensors for practical applications are discussed and proposed.展开更多
Actinide-based catalysts have been regarded as promising candidates for N_(2) fixation owing to their unique 5f orbital with flexible oxidation states.Herein,we report for the first time the dispersion of uranium(U)si...Actinide-based catalysts have been regarded as promising candidates for N_(2) fixation owing to their unique 5f orbital with flexible oxidation states.Herein,we report for the first time the dispersion of uranium(U)single atoms on TiO_(2) nanosheets via oxygen vacancy confinement for N_(2) electroreduction.The single-atom U catalyst exhibited a high NH_(3) yield of 40.57μg h^(-1) mg^(-1),with a reasonably high Faraday efficiency of 25.77%,ranking first among the reported nitrogen-free catalysts.Isotope-labeling operando synchrotron infrared spectroscopy verifies that the key*N_(2)H_(y) intermediate species was derived from the N_(2) gas of the feed.By using operando X-ray absorption spectroscopy,we found enhanced metal-support interaction between U single atoms and TiO_(2) lattice with more U-O_(latt) coordination under working conditions.Theoretical simulations suggest that the evolved 1O_(ads)-U-4O_(latt) moieties act as a critical electronfeedback center,lowering the thermodynamic energy barrier for the N_(2) dissociation and the first hydrogenation step.This work provides the possibility of tailoring the interaction between metal active sites and supports for designing high-performance actinide-based single-atom catalysts.展开更多
Engineering the electronic properties of catalysts to target intermediate adsorption energy as well as harvest high selectivity represents a promising strategy to design advanced electrocatalysts for efficient CO_(2)e...Engineering the electronic properties of catalysts to target intermediate adsorption energy as well as harvest high selectivity represents a promising strategy to design advanced electrocatalysts for efficient CO_(2)electroreduction.Herein,a synergistical tuning on the electronic structure of the Cd Se nanorods is proposed for boosting electrochemical reduction of CO_(2).The synergy of Ag doping coupled with Se vacancies tuned the electronic structure of the CdSe nanorods,which shows the metalloid characterization and thereby the accelerated electron transfer of CO_(2)electroreduction.Operando synchrotron radiation Fourier transform infrared spectroscopy and theoretical simulation revealed that the Ag doping and Se vacancies accelerated the CO_(2)activation process and lowered the energy barrier for the conversion from CO_(2)to;COOH;as a result,the performance of CO_(2)electroreduction was enhanced.The as-obtained metalloid Ag-doped CdSe nanorods exhibited a 2.7-fold increment in current density and 1.9-fold Faradaic efficiency of CO compared with the pristine CdSe nanorod.展开更多
Fast actuation with nanoprecision over a large range has been a challenge in advanced intelligent manufacturing like lithography mask aligner.Traditional stacked stage method works effectively only in a local,limited ...Fast actuation with nanoprecision over a large range has been a challenge in advanced intelligent manufacturing like lithography mask aligner.Traditional stacked stage method works effectively only in a local,limited range,and vibration coupling is also challenging.Here,we design a dual mechanism multimodal linear actuator(DMMLA)consisted of piezoelectric and electromagnetic costator and coslider for producing macro-,micro-,and nanomotion,respectively.A DMMLA prototype is fabricated,and each working mode is validated separately,confirming its fast motion(0~50 mm/s)in macromotion mode,micromotion(0~135μm/s)and nanomotion(minimum step:0~2 nm)in piezoelectric step and servomotion modes.The proposed dual mechanism design and multimodal motion method pave the way for next generation high-precision actuator development.展开更多
基金supported by the National Natural Science Foundation of China(No.52470174)the Joint Research Project on Ecological Protection and High-Quality Development in the Yellow River Basin,China(No.2022-YRUC-01-050209-01).
文摘Soil microbial communities and grassland ecosystem processes are increasingly confronted with multiple global change factors(GCFs).There is still a lack of research on how these multiple GCFs interact and impact soil microbial communities and their functions.To address this gap,we conducted a simulation experiment to examine the individual and interactive effects of the four most critical and prevalent GCFs,elevated carbon dioxide concentration(eCO_(2)),elevated temperature(eT),decreased precipitation(dP),and elevated nitrogen(N)deposition(eN).This study focused on their effects on soil physicochemical properties,bacterial and fungal communities,and extracellular enzyme activities(EEAs)related to carbon(C),N,and phosphorus(P)cycles in a temperate grassland.Results showed that eCO_(2),eN,and dP tended to increase EEAs,while having neutral effects on microbial diversity and community composition.On the other hand,eT resulted in decreases in soil pH,total C,total N,EEAs,and microbial diversity,but increases in plant biomass,total P,microbial richness,and network complexity and stability.This shift in the nutrient limitation from P to N under warming conditions resulted in decoupling of nutrients.Neutral or slightly negative relationships were found between enzyme activities and microbial richness,diversity,and dominant species,and the responses of microbial communities and ecological functions were asynchronous under GCFs.Importantly,our results revealed significant higher-order interactions among GCFs and found that they had notable effects on soil physicochemical properties as well as on microbial communities and ecological functions.These findings provide valuable insights and suggestions for ecological adaptations to future global changes.
基金co-supported by the National Natural Science Foundation of China(Nos.11932001,12272003,U224126)。
文摘To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplinary coupling pose significant challenges to mission design.This paper first investigates the typical design scheme of the airbag landing system for manned spacecrafts to obtain basic insight.A comprehensive review of the past research works on the airbag landing system is then carried out from three aspects:dynamic modeling,performance optimization,and experimental study.The airbag landing system for spacecraft is a rigid-flexible-gas coupling system,which can be modeled through multi-body dynamics or finite element method.Different venting structures and optimization methods are introduced to improve the cushioning performance.Experimental setups for drop test and airbag test are developed to verify the design feasibility.Finally,this paper proposes key issues in the dynamics analysis and design optimization of the airbag landing system for future study.
基金supported by the Natural Science Foundation of Zhejiang Province(ZCLZ24B0301)the Lhasa Central Government Guiding Local Science and Technology Development Funds(No.LSKJ202458)the National Natural Science Foundation of China(No.22472150)。
文摘The electrocatalytic furfural oxidation reaction(FFOR)represents an economical and promising technology to replace conventional oxygen evolution reaction,enabling the co-production of high value chemicals and H_(2).Regulating the adsorption of furfural(FF)and OH^(-)species holds paramount importance in enhancing the overall performance.Herein,we have developed a unique CuO catalyst enriched with oxygen vacancies(O_(v)-CuO)resulting from the electrochemical reconstruction ofα-Cu_(2)S,which demonstrates exceptional FFOR performance,with a conversion of 95.3%,near-perfect selectivity and Faraday efficiency(FE)for furoic acid(FA)at 1.475 V vs.RHE.The study provides detailed comparison of the structural evolution of different sulfide precatalysts and their impact on FFOR.Furthermore,it delves into the structure-activity relationship through a combination of characterization and theoretical calculations.The O_(v)-CuO not only enhances OH^(-)adsorption,changes the rate-determining step,but also reduces the reaction energy barrier toward FFOR.Additionally,a much lower cell voltage is required to coproduce FA and hydrogen in the two-electrode co-electrolysis system.This work would provide valuable insights into the reaction mechanism of FFOR on Cu based catalysts and establish guidelines for designing defective electrocatalysts for biomass conversion.
基金supported by the National Key Research and Development Program of China(2023YFB3809400)the National Natural Science Foundation of China(Grant nos.T2125008,92163203,and 52371234)+1 种基金the Hong Kong,Macao,and Taiwan Science and Technology Cooperation Project for Science and Technology Innovation Plan of Shanghai(23520760600)the Fundamental Research Funds for the Central Universities.
文摘Elastic strain constitutes a decisive factor in determining the recoverable deformability of thermoelectric materials.Plastic deformation for microstructure engineering has been demonstrated as a viable approach to enhance the elastic strain.However,this approach is highly dependent on the material's plasticity,which is rather limited by the rigidity for the majority of inorganic semiconducting thermoelectric materials.Thermocouple materials,as metallic thermoelectric materials,possess a favorable plasticity,motivating this work to focus on the elastic bendability of a metallic thermoelectric generator that is composed of K-type thermocouple components,namely p-type Ni_(90)Cr_(10) and n-type Ni_(95)Al_(2)Mn_(2)Si.The cold-rolling process enables a large elastic modulus and a high yield strength,thanks to the texturized direction along<111>,and dense dislocations and refined grains,respectively,eventually resulting in a 400%increase in the elastic strain.Such superior elasticity ensures the preservation of the initial transport properties for the rolled films even after being bent 100000 times within a radius of~8 mm.A power output of~414μW is achieved in a ten-leg flexible thermoelectric device,suggesting its substantial potential for powering wearable electronics.
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.
文摘This study investigates the geological background of the August 7-8, 2010 Zhouqu debris flows in the northwestern Chinese province of Gansu, and possible future occurrence of such hazards in the peri-Tibetan Plateau (TP) regions. Debris flows are a more predictable type of landslide because of its strong correlation with extreme precipitation. However, two factors affecting the frequency and magnitude of debris flows: very fine scale precipitation and degree of fracture of bedrock, both defy direct observations. Annual mean Net Primary production (NPP) is used as a surrogate for regional precipitation with patchiness filtered out, and gravity satellite measured regional mass changes as an indication of bedrock cracking, through the groundwater as the nexus.?The GRACE measurements indicate a region (to the north east of TP) of persistent mass gain (started well before the 2008 Wenchuan earthquake), likely due to increased groundwater percolation. While in the neighboring agricultural region further to the north east, there are signal of decreased fossil water reservoir. The imposed stress fields by large scale increase/decrease groundwater may contribute to future geological instability of this region. Zhouqu locates right on the saddle of the gravity field anomaly. The region surrounding the Bay of Bangle (to the southeast of TP) has a similar situation. To investigate future changes in extreme precipitation, the other key player for debris flows, the “pseudo-climate change” experiments of a weather model forced by climate model provided perturbations on the thermal fields are performed and endangered locations are identified. In the future warmer climate, extreme precipitation will be more severe and debris will be more frequent and severe.
文摘Distance higher education is an important component of the Chinese higher education.How to enhance the quality of distance higher education is one of the key issues to be addressed in the research areas of distance education and higher education.As a crucial step to quality improvement,the constitution of accreditation system in distance higher education balances the benefits of all parties involved.This paper explores the American accreditation system of higher education and distance education and concludes with suggestions for the constitution of the Chinese quality assurance system:1)establishing third-party institutions to share part of the government roles;2)constituting the accreditation system;3)setting up appropriate standards;4)publicizing results of quality assurance work;and 5)building internal quality assurance mechanism.This paper is aimed to provide some reference to the constitution of accreditation system of distance higher education in China,facilitate the solution of quality problems in distance education,and promote the continuous improvement and development of distance education in China.
文摘Thermoelectric generators,with the unique ability to convert temperature gradients into electricity,have long been acknowledged as a sustainable technique for waste heat recovery.The remarkable advancements in both thermoelectric materials and devices have substantially propelled the practical applications of thermoelectric generators.The capability of generating electricity through the temperature gradient between the human body and the ambient environment highlights the significant potential of flexible thermoelectric devices as self-powered energy sources for wearable electronics.However,this leaves a formidable challenge with respect to the bendability of the high-performance,yet inherently brittle,inorganic thermoelectric materials.The strategies of dislocationization and grain refinement have been reported to effectively enhance the elastic strain,thereby ensuring fully recoverable bendability for inorganic thermoelectric materials[1,2].This offers a versatile approach for enhancing the elastic bendability of inorganic thermoelectric generators.
基金supported by the National Key Research and Development Program of China(2023YFB3809400)the National Natural Science Foundation of China(Grant Nos.T2125008,92163203,52371234,and 92263108)+1 种基金the Innovation Program of Shanghai Municipal Education Commission(2021‐01‐07‐00‐07‐E00096)the Fundamental Research Funds for the Central Universities.
文摘Functionalities of materials tightly relate to the atomic and electronic structures,the coupling between which through lattice and charge gives birth to thermoelectricity,enabling a direct heat‐electricity conversion.Booming wearable electronics nowadays urgently demand thermoelectric film generators as self‐powered units using body and environment heats,of which highly recoverable deformability and power are the core challenges.This indicates the great importance of elasticity since a plastic deformation otherwise actuates lattice slips to unsecure both thermoelectricity and recoverability.It is illustrated in this work texturization and dislocations for enhancing elasticity in cold‐rolled constantan foils,a metal thermoelectric enabling one of the highest power outputs near room temperature for deformable wearables.The device can work in a purely elastic region,to secure orders of magnitude improvement in recoverable bendability with an extraordinary specific power density,at a bending radius down to 5mm fitting the curvature of an adult's little finger.This work delivers a strategy for bringing robust deformability to thermoelectricity for powering wearable electronics.
基金supported by the National Natural Science Foundation of China(Nos.12105287 and 12205304)。
文摘Renewable electricity-driven CO evolu-tion from CO_(2)offers a promising route for sustainable chemical production.Single-atom alloy(SAA)catalysts are emerging as promising candidates for electrochemical CO_(2)reduction.Howev-er,the dynamic nature of SAAs within their local microenvironment often com-plicates our understanding of the under-lying mechanisms that contribute to their enhanced performance.In this study,we introduce a single-atom Co-modified Au nanoparticle catalyst(Co_(1)O_(x)@Au)for the electrocatalytic re-duction of CO_(2)to CO.Using operando X-ray absorption spectroscopy(XAS),we observe the dynamic transformation of Co_(1)O_(x)@Au into a low-valence Co_(1)Au SAA,driven by the applied voltages.This behavior strengthens the atomic interaction between Au and Co,thus ensuring a reinforced adsorption of the crucial^(*)COOH intermediate,which is corroborated by operan-do synchrotron-radiation Fourier transform infrared spectroscopy(SR-FTIR).Furthermore,the strengthened Au-Co interaction facilitates the subsequent desorption of the^(*)CO interme-diate,allowing for efficient CO formation and release.These insights highlight the self-opti-mization behavior of SAAs towards improving CO_(2)reduction selectivity.
基金supported by the Ministry of Science and Technology of China(2016YFA0200103)the National Natural Science Foundation of China(51672153,21975141)the National Program for Support of Top-notch Young Professionals.
文摘Hybrid perovskite possesses excellent photoelectric properties,including large light-absorption capacity and high carrier mobility,and is an ideal light-absorbing material for photoelectric devices.The grain size and compactness of hybrid perovskite are key factors affecting the performance of photoelectric devices.The photocurrent and photoresponsivity of these devices are relatively low because of the rapidly recombined photoexcited electron-hole pairs in hybrid perovskite.Herein,we develop a facile two-step chemical vapor deposition(CVD)method to synthesize a high-quality van der Waals(vd Ws)MAPb I3/graphene heterostructure for high-performance image sensor.We introduced inorganic sources(PbI2)to vd Ws epitaxially grown Pb I2 film on a seamless graphene monolayer film template through CVD.Methylammonium iodide(MAI)was then reintroduced to prepare the vd Ws MAPb I3/graphene heterostructure.The MAPb I3 layer is composed of densely packed,large-size grains and displays a smooth surface.High photoresponsivity of 107A/W is achieved in the corresponding photodetector.Inspired by the human visual system,we designed a flexible photodetector array containing(24?24)pixels,achieving perfect image recognition and color discrimination.Our study may greatly facilitate the construction of high-performance optoelectronic devices in artificial retina,biomedical imaging,remote sensing,and optical communication.
基金National Key Basic Research and Development Program,Grant/Award Number:2016YFA0200103National Natural Science Foundation of China,Grant/Award Numbers:21975141,51672153National Program for Support of Top-notch Young Professionals,Grant/Award Number:N/A。
文摘Skin,the largest organ in the human body,is sensitive to external stimuli.In recent years,an increasing number of skin-inspired electronics,including wearable electronics,implantable electronics,and electronic skin,have been developed because of their broad applications in healthcare and robotics.Physical sensors are one of the key building blocks of skin-inspired electronics.Typical physical sensors include mechanical sensors,temperature sensors,humidity sensors,electrophysiological sensors,and so on.In this review,we systematically review the latest advances of skin-inspired mechanical sensors,temperature sensors,and humidity sensors.The working mechanisms,key materials,device structures,and performance of various physical sensors are summarized and discussed in detail.Their applications in health monitoring,human disease diagnosis and treatment,and intelligent robots are reviewed.In addition,several novel properties of skin-inspired physical sensors such as versatility,self-healability,and implantability are introduced.Finally,the existing challenges and future perspectives of physical sensors for practical applications are discussed and proposed.
基金supported by the National Key R&D Program of China(2021YFA1600800)the National Natural Science Foundation of China(12025505,21976147,and 22106126)+3 种基金the University of China Innovation Program of Anhui Province(GXXT-2020-053)the Youth Innovation Promotion Association CAS(2015366)Open Fund Project of State Key Laboratory of Environmentally Friendly Energy Materials(20kfhg08)Collaborative Innovation Program of Hefei Science Center(2021HSC-CIP006)。
文摘Actinide-based catalysts have been regarded as promising candidates for N_(2) fixation owing to their unique 5f orbital with flexible oxidation states.Herein,we report for the first time the dispersion of uranium(U)single atoms on TiO_(2) nanosheets via oxygen vacancy confinement for N_(2) electroreduction.The single-atom U catalyst exhibited a high NH_(3) yield of 40.57μg h^(-1) mg^(-1),with a reasonably high Faraday efficiency of 25.77%,ranking first among the reported nitrogen-free catalysts.Isotope-labeling operando synchrotron infrared spectroscopy verifies that the key*N_(2)H_(y) intermediate species was derived from the N_(2) gas of the feed.By using operando X-ray absorption spectroscopy,we found enhanced metal-support interaction between U single atoms and TiO_(2) lattice with more U-O_(latt) coordination under working conditions.Theoretical simulations suggest that the evolved 1O_(ads)-U-4O_(latt) moieties act as a critical electronfeedback center,lowering the thermodynamic energy barrier for the N_(2) dissociation and the first hydrogenation step.This work provides the possibility of tailoring the interaction between metal active sites and supports for designing high-performance actinide-based single-atom catalysts.
基金supported by the National Natural Science Foundation of China(12025505 and 21873050)China Ministry of Science and Technology(2017YFA0208300)+1 种基金the Open Fund Project of State Key Laboratory of Environmentally Friendly Energy Materials(20KFHG08)the Youth Innovation Promotion Association CAS(CX2310007007 and CX2310000091)。
文摘Engineering the electronic properties of catalysts to target intermediate adsorption energy as well as harvest high selectivity represents a promising strategy to design advanced electrocatalysts for efficient CO_(2)electroreduction.Herein,a synergistical tuning on the electronic structure of the Cd Se nanorods is proposed for boosting electrochemical reduction of CO_(2).The synergy of Ag doping coupled with Se vacancies tuned the electronic structure of the CdSe nanorods,which shows the metalloid characterization and thereby the accelerated electron transfer of CO_(2)electroreduction.Operando synchrotron radiation Fourier transform infrared spectroscopy and theoretical simulation revealed that the Ag doping and Se vacancies accelerated the CO_(2)activation process and lowered the energy barrier for the conversion from CO_(2)to;COOH;as a result,the performance of CO_(2)electroreduction was enhanced.The as-obtained metalloid Ag-doped CdSe nanorods exhibited a 2.7-fold increment in current density and 1.9-fold Faradaic efficiency of CO compared with the pristine CdSe nanorod.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51772005 and 51072003)Beijing Key Laboratory for Magnetoeletric Materials and Devices.
文摘Fast actuation with nanoprecision over a large range has been a challenge in advanced intelligent manufacturing like lithography mask aligner.Traditional stacked stage method works effectively only in a local,limited range,and vibration coupling is also challenging.Here,we design a dual mechanism multimodal linear actuator(DMMLA)consisted of piezoelectric and electromagnetic costator and coslider for producing macro-,micro-,and nanomotion,respectively.A DMMLA prototype is fabricated,and each working mode is validated separately,confirming its fast motion(0~50 mm/s)in macromotion mode,micromotion(0~135μm/s)and nanomotion(minimum step:0~2 nm)in piezoelectric step and servomotion modes.The proposed dual mechanism design and multimodal motion method pave the way for next generation high-precision actuator development.
