The Knudsen effusion cell is often used to grow high-quality Cu(In,Ga)Se_(2)(CIGS)thin film in coevaporation processes.However,the traditional single-heating Knudsen effusion cell cannot deliver complete metal selenid...The Knudsen effusion cell is often used to grow high-quality Cu(In,Ga)Se_(2)(CIGS)thin film in coevaporation processes.However,the traditional single-heating Knudsen effusion cell cannot deliver complete metal selenides during the whole deposition process,particularly for a low-temperature deposition process,which is probably due to the condensation and droplet ejection at the nozzle of the crucible.In this study,thermodynamics analysis is conducted to decipher the reason for this phenomenon.Furthermore,a new single-heating Knudsen effusion is proposed to solve this difficult problem,which leads to an improvement in the quality of CIGS film and a relative increase in conversion efficiency of 29%at a growth rate of about 230 nmmin1,compared with the traditional efficiency in a lowtemperature rapid-deposition process.展开更多
Previous studies have shown that reptiles are capable of spatial learning and learn to locate important environmental resources so that they can return to those locations at a future time,when needed.Lizards improve t...Previous studies have shown that reptiles are capable of spatial learning and learn to locate important environmental resources so that they can return to those locations at a future time,when needed.Lizards improve their adaptability and survival by learning the position of their shelter in a complex environment.This behavior raises the question,whether lizards can sense danger,such as a trap,in their surroundings,by determining the location of the trap and avoiding it.In the present study,we used a pitfall trap to test if steppe toad-headed agama,Phrynocephalus frontalis,can learn to recognize the position of the trap and avoid it.Our results revealed that the percentage of activity time in the trap area was significantly reduced(P < 0.001) and the time of drop trap was also significantly reduced(P = 0.00631).The number of burrows dug by lizards distributed in the trap area was the least.Reduced activity time in the trap area was observed to have no obvious relationship with the drop in the number of burrows.The present study,therefore,demonstrates that P.frontalis are capable of learning the avoidance of a trap by locating its position.The findings offer significant insight in the understanding of reptilian behavior,which is important in the study of the role of reptiles in global ecology,especially because they are often very sensitive to environmental changes.展开更多
An emergency platform is an informatization support platform for disaster information perception,disaster situa-tional awareness,and emergency decision command.This is a key tool for ensuring the efficiency and effect...An emergency platform is an informatization support platform for disaster information perception,disaster situa-tional awareness,and emergency decision command.This is a key tool for ensuring the efficiency and effectiveness of emergency responses.Numerous large countries have conducted in-depth research on the key technologies of emergency platforms.Over the past 20 years,with the reform of emergency management mechanisms,China has developed two generations of emergency platform systems.This paper reviews the two generations of emergency platforms and summarizes their key technologies including multi-source-based monitoring and early warning,multi-hazard risk assessment,“scenario-response”-based decision support,synthetical forecasting based on in-cident chain,and emergency common operational picture(COP)for command and dispatch.Future research directions for the next generation emergency platforms are also proposed.展开更多
Si materials are widely considered to be the next-generation anode to replace the current commercial graphite-based anode due to its high energy density.However,the large volume variation of silicon during(de)lithiati...Si materials are widely considered to be the next-generation anode to replace the current commercial graphite-based anode due to its high energy density.However,the large volume variation of silicon during(de)lithiation process leads to rapid capacity decay,hindering its commercial application.Although the various hollow structure designs of Si nanomaterials have improved their cycling stability in the laboratory,the high-pressure calendering process in the current industrial electrode preparation process might collapse the hollow structure and weaken the structural advantages of hollow silicon anode materials.In this work,a silicon carbon composite material(Si@3DC)in which Si nanoparticles were anchored on a three-dimensional carbon framework through carbon films was prepared by a simple proton exchange method.The three-dimensional carbon framework with multiple hierarchical pores of Si@3DC was compatible with the high-pressure calendering process,but also could provide expansion space for Si nanoparticles during the lithiation process,and ensure good electronic and ionic conductivity.The carbon film on the surface of Si nanoparticles promoted the formation of stable solid electrolyte interphase(SEI)films,ensuring the good cycle stability of Si@3DC.展开更多
Chalcopyrite Cu(In,Ga)Se_(2)(CIGS) thin films deposited in a low-temperature process(450℃) usually produce fine grains and poor crystallinity. Herein, different Ag treatment processes, which can decrease the melting ...Chalcopyrite Cu(In,Ga)Se_(2)(CIGS) thin films deposited in a low-temperature process(450℃) usually produce fine grains and poor crystallinity. Herein, different Ag treatment processes, which can decrease the melting temperature and enlarge band gap of the CIGS films, were employed to enhance the quality of thin films in a low-temperature deposition process. It is demonstrated that both the Ag precursor and Ag surface treatment process can heighten the crystallinity of CIGS films and the device efficiency. The former is more obvious than the latter. Furthermore, the Urbach energy is also reduced with Ag doping. This work aims to provide a feasible Ag-doping process for the high-quality CIGS films in a low-temperature process.展开更多
基金The work was supported by the National Key R&D Program of China(2018YFB1500200)the National Natural Science Foundation of China(61774089 and 61974076)the Natural Science Foundation of Tianjin(18JCZDJC31200).
文摘The Knudsen effusion cell is often used to grow high-quality Cu(In,Ga)Se_(2)(CIGS)thin film in coevaporation processes.However,the traditional single-heating Knudsen effusion cell cannot deliver complete metal selenides during the whole deposition process,particularly for a low-temperature deposition process,which is probably due to the condensation and droplet ejection at the nozzle of the crucible.In this study,thermodynamics analysis is conducted to decipher the reason for this phenomenon.Furthermore,a new single-heating Knudsen effusion is proposed to solve this difficult problem,which leads to an improvement in the quality of CIGS film and a relative increase in conversion efficiency of 29%at a growth rate of about 230 nmmin1,compared with the traditional efficiency in a lowtemperature rapid-deposition process.
基金approved by the Animal Ethics Committee of the Institute of Zoology,Chinese Academy of Sciences(IOZ14001)College of Life Sciences,Inner Mongolia Normal University(31660615)
文摘Previous studies have shown that reptiles are capable of spatial learning and learn to locate important environmental resources so that they can return to those locations at a future time,when needed.Lizards improve their adaptability and survival by learning the position of their shelter in a complex environment.This behavior raises the question,whether lizards can sense danger,such as a trap,in their surroundings,by determining the location of the trap and avoiding it.In the present study,we used a pitfall trap to test if steppe toad-headed agama,Phrynocephalus frontalis,can learn to recognize the position of the trap and avoid it.Our results revealed that the percentage of activity time in the trap area was significantly reduced(P < 0.001) and the time of drop trap was also significantly reduced(P = 0.00631).The number of burrows dug by lizards distributed in the trap area was the least.Reduced activity time in the trap area was observed to have no obvious relationship with the drop in the number of burrows.The present study,therefore,demonstrates that P.frontalis are capable of learning the avoidance of a trap by locating its position.The findings offer significant insight in the understanding of reptilian behavior,which is important in the study of the role of reptiles in global ecology,especially because they are often very sensitive to environmental changes.
基金the China National Natural Science Foundation(Grant Nos.72104123,72004113,and 71790613).
文摘An emergency platform is an informatization support platform for disaster information perception,disaster situa-tional awareness,and emergency decision command.This is a key tool for ensuring the efficiency and effectiveness of emergency responses.Numerous large countries have conducted in-depth research on the key technologies of emergency platforms.Over the past 20 years,with the reform of emergency management mechanisms,China has developed two generations of emergency platform systems.This paper reviews the two generations of emergency platforms and summarizes their key technologies including multi-source-based monitoring and early warning,multi-hazard risk assessment,“scenario-response”-based decision support,synthetical forecasting based on in-cident chain,and emergency common operational picture(COP)for command and dispatch.Future research directions for the next generation emergency platforms are also proposed.
基金supported financially by the National Key Research and Development Program of China(No.2017YFB0307701).
文摘Si materials are widely considered to be the next-generation anode to replace the current commercial graphite-based anode due to its high energy density.However,the large volume variation of silicon during(de)lithiation process leads to rapid capacity decay,hindering its commercial application.Although the various hollow structure designs of Si nanomaterials have improved their cycling stability in the laboratory,the high-pressure calendering process in the current industrial electrode preparation process might collapse the hollow structure and weaken the structural advantages of hollow silicon anode materials.In this work,a silicon carbon composite material(Si@3DC)in which Si nanoparticles were anchored on a three-dimensional carbon framework through carbon films was prepared by a simple proton exchange method.The three-dimensional carbon framework with multiple hierarchical pores of Si@3DC was compatible with the high-pressure calendering process,but also could provide expansion space for Si nanoparticles during the lithiation process,and ensure good electronic and ionic conductivity.The carbon film on the surface of Si nanoparticles promoted the formation of stable solid electrolyte interphase(SEI)films,ensuring the good cycle stability of Si@3DC.
基金The work was supported by the National Key R&D Program of China(No.2018YFB1500200)National Natural Science Foundation of China(Nos.61774089 and 61974076)Natural Science Foundation of Tianjin(No.18JCZDJC31200)。
文摘Chalcopyrite Cu(In,Ga)Se_(2)(CIGS) thin films deposited in a low-temperature process(450℃) usually produce fine grains and poor crystallinity. Herein, different Ag treatment processes, which can decrease the melting temperature and enlarge band gap of the CIGS films, were employed to enhance the quality of thin films in a low-temperature deposition process. It is demonstrated that both the Ag precursor and Ag surface treatment process can heighten the crystallinity of CIGS films and the device efficiency. The former is more obvious than the latter. Furthermore, the Urbach energy is also reduced with Ag doping. This work aims to provide a feasible Ag-doping process for the high-quality CIGS films in a low-temperature process.
