Sandwich-style memristor devices were synthesized by electrochemical deposition with a ZnO film serving as the active layer between Al-doped ZnO （AZO） and Au electrodes. The carrier concentration of the ZnO films is...Sandwich-style memristor devices were synthesized by electrochemical deposition with a ZnO film serving as the active layer between Al-doped ZnO （AZO） and Au electrodes. The carrier concentration of the ZnO films is controlled by adding HNO3 during the growth process. A resulting increase in carrier concentration from 10^17 to 10^19 cm^-3 was observed, along with a corresponding drop in the on--off ratio from 6,437% to 100%. The resistive switching characteristics completely disappeared when the carrier concentration was above 1029 cm-3, making it unsuitable for a memory device. The decreasing switching ratio is attributed to a reduction in the driving force for oxygen vacancy drift. Systematic analysis of the migration of oxygen vacancies is presented, including the concentration gradient and electrical potential gradient. Such oxygen vacancy migration dynamics provide insight into the mechanisms of the oxygen vacancy drift and provide valuable information for industrial production of memristor devices.展开更多
为了给“双碳”目标下我国交通运输行业发展路径及政策制定提供学术参考,基于对数平均迪氏指数法(Logarithmic Mean Divisia Index, LMDI),选取交通运输碳排放系数、运输方式结构、客货运结构和换算周转量4个因素定量分析了2010—2020...为了给“双碳”目标下我国交通运输行业发展路径及政策制定提供学术参考,基于对数平均迪氏指数法(Logarithmic Mean Divisia Index, LMDI),选取交通运输碳排放系数、运输方式结构、客货运结构和换算周转量4个因素定量分析了2010—2020年间我国交通运输行业碳排放变化的主要机理,并结合与美国、日本、德国等已达峰国家相应驱动因素的类比分析,提出我国交通运输行业面向“双碳”目标的路径建议与实现措施。研究结果表明:交通运输碳排放系数、运输方式结构、换算周转量是驱动我国交通运输行业碳排放的关键因素,2010—2020年的贡献率均值分别为24.8%, 27.2%和42.0%,故需要从这3个因素入手,制定针对性的政策来实现交通运输行业“双碳”目标;客货运结构对我国交通运输行业“双碳”目标的影响较弱,2010—2020年的贡献率均值为6.0%,即总周转量中客运和货运占比对我国交通运输行业碳排放的影响不大,但2020年由于新冠疫情的影响,客货运结构对我国交通运输行业碳排放的贡献率升高至43.3%,需要重点关注疫情时期的这一新变化。展开更多
Wind controls the formation and development of sand dunes.Therefore,understanding the wind regimes is necessary in sand dune research.In this study,we combined the wind data from 2017 to 2019 at four meteorological st...Wind controls the formation and development of sand dunes.Therefore,understanding the wind regimes is necessary in sand dune research.In this study,we combined the wind data from 2017 to 2019 at four meteorological stations(Cherigele and Wuertabulage stations in the lake basins,and Yikeri and Sumujilin stations on the top of sand dunes)in the hinterland of the Badain Jaran Desert in China,with high resolution Google Earth images to analyze the correlation between the wind energy environments and dune morphology.The results of data analysis indicated that both the wind direction and sand drift intensity exhibited notable spatial and temporal variations.The highest level of wind activity was observed in spring.Northwesterly and northeasterly winds were the dominant in the Badain Jaran Desert.At the Cherigele,Wuertabulage,and Yikeri stations,the drift potential(DP)was below 200.00 vector units(VU).The wind energy environments in most areas could be classified as low-energy environments.The resultant drift direction differed at different stations and in different seasons,but the overall direction was mainly the southeast.The resultant drift potential(RDP)/DP ratio was greater than 0.30 in most parts of the study area,suggesting that the wind regimes mainly exhibited unimodal or bimodal characteristics.Differences between the thermodynamic properties and the unique landscape settings of lakes and sand dunes could alter the local circulation and intensify the complexity of the wind regimes.The wind regimes were weaker in the lake basins than on the top of sand dunes.Transverse dunes were the most dominant types of sand dunes in the study area,and the wind regimes at most stations were consistent with sand dune types.Wind was thus the main dynamic factor affecting the formation of sand dunes in the Badain Jaran Desert BJD.The results of this study are important for understanding the relationship between the wind regimes and aeolian landforms of the dune field in the deserts.展开更多
The shear stress generated by the wind on the land surface is the driving force that results in the wind erosion of the soil.It is an independent factor influencing soil wind erosion.The factors related to wind erosiv...The shear stress generated by the wind on the land surface is the driving force that results in the wind erosion of the soil.It is an independent factor influencing soil wind erosion.The factors related to wind erosivity,known as submodels,mainly include the weather factor(WF)in revised wind erosion equation(RWEQ),the erosion submodel(ES)in wind erosion prediction system(WEPS),as well as the drift potential(DP)in wind energy environmental assessment.However,the essential factors of WF and ES contain wind,soil characteristics and surface coverings,which therefore results in the interdependence between WF or ES and other factors(e.g.,soil erodible factor)in soil erosion models.Considering that DP is a relative indicator of the wind energy environment and does not have the value of expressing wind to induce shear stress on the surface.Therefore,a new factor is needed to express accurately wind erosivity.Based on the theoretical basis that the soil loss by wind erosion(Q)is proportional to the shear stress of the wind on the soil surface,a new model of wind driving force(WDF)was established,which expresses the potential capacity of wind to drive soil mass in per unit area and a period of time.Through the calculations in the typical area,the WDF,WF and DP are compared and analyzed from the theoretical basis,construction goal,problem-solving ability and typical area application;the spatial distribution of soil wind erosion intensity was concurrently compared with the spatial distributions of the WDF,WF and DP values in the typical area.The results indicate that the WDF is better to reflect the potential capacity of wind erosivity than WF and DP,and that the WDF model is a good model with universal applicability and can be logically incorporated into the soil wind erosion models.展开更多
The wide valley of the Yarlung Zangbo River is one of the most intense areas in terms of aeolian activity on the Tibetan Plateau,China.In the past,the evaluation of the intensity of aeolian activity in the Quxu–Sangr...The wide valley of the Yarlung Zangbo River is one of the most intense areas in terms of aeolian activity on the Tibetan Plateau,China.In the past,the evaluation of the intensity of aeolian activity in the Quxu–Sangri section of the Yarlung Zangbo River Valley was mainly based on data from the old meteorological stations,especially in non-sandy areas.In 2020,six new meteorological stations,which are closest to the new meteorological stations,were built in the wind erosion source regions(i.e.,sandy areas)in the Quxu–Sangri section.In this study,based on mathematical statistics and empirical orthogonal function(EOF)decomposition analysis,we compared the difference of the wind regime between new meteorological stations and old meteorological stations from December 2020 to November 2021,and discussed the reasons for the discrepancy.The results showed that sandy and non-sandy areas differed significantly regarding the mean velocity(8.3(±0.3)versus 7.7(±0.3)m/s,respectively),frequency(12.9%(±6.2%)versus 2.9%(±1.9%),respectively),and dominant direction(nearly east or west versus nearly north or south,respectively)of sand-driving winds,drift potential(168.1(±77.3)versus 24.0(±17.9)VU(where VU is the vector unit),respectively),resultant drift potential(92.3(±78.5)versus 8.7(±9.2)VU,respectively),and resultant drift direction(nearly westward or eastward versus nearly southward or northward,respectively).This indicated an obvious spatial variation in the wind regime between sandy and non-sandy areas and suggested that there exist problems when using wind velocity data from non-sandy areas to evaluate the wind regime in sandy areas.The wind regime between sandy and non-sandy areas differed due to the differences in topography,heat flows,and their coupling with underlying surface,thereby affecting the local atmospheric circulation.Affected by large-scale circulations(westerly jet and Indian monsoon systems),both sandy and non-sandy areas showed similar seasonal variations in their respective wind regime.These find展开更多
A series of novel rhenium(I) 2,2'-bipyridyl complexes [fac-Re(4,4'-di-COOEt-bpy) -(CO)3(Xpy)PF6], where bpy is 2,2'-bipyridine, py is pyridine and X is 3-methyl, 3-hydroxy, or 3-amino, were synthesized, th...A series of novel rhenium(I) 2,2'-bipyridyl complexes [fac-Re(4,4'-di-COOEt-bpy) -(CO)3(Xpy)PF6], where bpy is 2,2'-bipyridine, py is pyridine and X is 3-methyl, 3-hydroxy, or 3-amino, were synthesized, their photophysical and electrochemical properties were studied. The Re(II/I) oxidation potentials decreased as the X group becomes more electron donating from H to 3-methyl, 3-hydroxy, or 3-amino, which might be a very convenient ways for adjusting the electron transfer driving force.展开更多
基金This work was supported by the National Basic Research Program of China （No. 2013CB932602）, the Program of Introducing Talents of Discipline to Universities （No. B14003）, National Natural Science Foundation of China （Nos. 51527802, 51372023 and 51232001）, Beijing Municipal Science ＆ Technology Commission, the Fundamental Research Funds for Central Universities.
文摘Sandwich-style memristor devices were synthesized by electrochemical deposition with a ZnO film serving as the active layer between Al-doped ZnO （AZO） and Au electrodes. The carrier concentration of the ZnO films is controlled by adding HNO3 during the growth process. A resulting increase in carrier concentration from 10^17 to 10^19 cm^-3 was observed, along with a corresponding drop in the on--off ratio from 6,437% to 100%. The resistive switching characteristics completely disappeared when the carrier concentration was above 1029 cm-3, making it unsuitable for a memory device. The decreasing switching ratio is attributed to a reduction in the driving force for oxygen vacancy drift. Systematic analysis of the migration of oxygen vacancies is presented, including the concentration gradient and electrical potential gradient. Such oxygen vacancy migration dynamics provide insight into the mechanisms of the oxygen vacancy drift and provide valuable information for industrial production of memristor devices.
基金funded by the National Natural Science Foundation of China(41871021)the Desert and Glacier Field Scientific Observation and Research Station of Lanzhou University(lzujbky-2021-sp16)。
文摘Wind controls the formation and development of sand dunes.Therefore,understanding the wind regimes is necessary in sand dune research.In this study,we combined the wind data from 2017 to 2019 at four meteorological stations(Cherigele and Wuertabulage stations in the lake basins,and Yikeri and Sumujilin stations on the top of sand dunes)in the hinterland of the Badain Jaran Desert in China,with high resolution Google Earth images to analyze the correlation between the wind energy environments and dune morphology.The results of data analysis indicated that both the wind direction and sand drift intensity exhibited notable spatial and temporal variations.The highest level of wind activity was observed in spring.Northwesterly and northeasterly winds were the dominant in the Badain Jaran Desert.At the Cherigele,Wuertabulage,and Yikeri stations,the drift potential(DP)was below 200.00 vector units(VU).The wind energy environments in most areas could be classified as low-energy environments.The resultant drift direction differed at different stations and in different seasons,but the overall direction was mainly the southeast.The resultant drift potential(RDP)/DP ratio was greater than 0.30 in most parts of the study area,suggesting that the wind regimes mainly exhibited unimodal or bimodal characteristics.Differences between the thermodynamic properties and the unique landscape settings of lakes and sand dunes could alter the local circulation and intensify the complexity of the wind regimes.The wind regimes were weaker in the lake basins than on the top of sand dunes.Transverse dunes were the most dominant types of sand dunes in the study area,and the wind regimes at most stations were consistent with sand dune types.Wind was thus the main dynamic factor affecting the formation of sand dunes in the Badain Jaran Desert BJD.The results of this study are important for understanding the relationship between the wind regimes and aeolian landforms of the dune field in the deserts.
基金This work was supported by the National Natural Science Foundation of China(41330746,41630747).
文摘The shear stress generated by the wind on the land surface is the driving force that results in the wind erosion of the soil.It is an independent factor influencing soil wind erosion.The factors related to wind erosivity,known as submodels,mainly include the weather factor(WF)in revised wind erosion equation(RWEQ),the erosion submodel(ES)in wind erosion prediction system(WEPS),as well as the drift potential(DP)in wind energy environmental assessment.However,the essential factors of WF and ES contain wind,soil characteristics and surface coverings,which therefore results in the interdependence between WF or ES and other factors(e.g.,soil erodible factor)in soil erosion models.Considering that DP is a relative indicator of the wind energy environment and does not have the value of expressing wind to induce shear stress on the surface.Therefore,a new factor is needed to express accurately wind erosivity.Based on the theoretical basis that the soil loss by wind erosion(Q)is proportional to the shear stress of the wind on the soil surface,a new model of wind driving force(WDF)was established,which expresses the potential capacity of wind to drive soil mass in per unit area and a period of time.Through the calculations in the typical area,the WDF,WF and DP are compared and analyzed from the theoretical basis,construction goal,problem-solving ability and typical area application;the spatial distribution of soil wind erosion intensity was concurrently compared with the spatial distributions of the WDF,WF and DP values in the typical area.The results indicate that the WDF is better to reflect the potential capacity of wind erosivity than WF and DP,and that the WDF model is a good model with universal applicability and can be logically incorporated into the soil wind erosion models.
基金supported by the Project for Establishing a Sand-dust Monitoring and Forecast System for the North-bank Settlement Area of the Yarlung Zangbo River (under the 13th Five-year Plan of the Tibet Autonomous Region, China)the Chinese Academy of Sciences Interdisciplinary Innovation Team and the Shannan City Science and Technology Plan Project (E129020301).
文摘The wide valley of the Yarlung Zangbo River is one of the most intense areas in terms of aeolian activity on the Tibetan Plateau,China.In the past,the evaluation of the intensity of aeolian activity in the Quxu–Sangri section of the Yarlung Zangbo River Valley was mainly based on data from the old meteorological stations,especially in non-sandy areas.In 2020,six new meteorological stations,which are closest to the new meteorological stations,were built in the wind erosion source regions(i.e.,sandy areas)in the Quxu–Sangri section.In this study,based on mathematical statistics and empirical orthogonal function(EOF)decomposition analysis,we compared the difference of the wind regime between new meteorological stations and old meteorological stations from December 2020 to November 2021,and discussed the reasons for the discrepancy.The results showed that sandy and non-sandy areas differed significantly regarding the mean velocity(8.3(±0.3)versus 7.7(±0.3)m/s,respectively),frequency(12.9%(±6.2%)versus 2.9%(±1.9%),respectively),and dominant direction(nearly east or west versus nearly north or south,respectively)of sand-driving winds,drift potential(168.1(±77.3)versus 24.0(±17.9)VU(where VU is the vector unit),respectively),resultant drift potential(92.3(±78.5)versus 8.7(±9.2)VU,respectively),and resultant drift direction(nearly westward or eastward versus nearly southward or northward,respectively).This indicated an obvious spatial variation in the wind regime between sandy and non-sandy areas and suggested that there exist problems when using wind velocity data from non-sandy areas to evaluate the wind regime in sandy areas.The wind regime between sandy and non-sandy areas differed due to the differences in topography,heat flows,and their coupling with underlying surface,thereby affecting the local atmospheric circulation.Affected by large-scale circulations(westerly jet and Indian monsoon systems),both sandy and non-sandy areas showed similar seasonal variations in their respective wind regime.These find
基金The authors would like to thank the National Natural Science Foundation of China(project 20128005.20376010)the Ministry of Science&Technology and the Ministry of Education for financial suppot.
文摘A series of novel rhenium(I) 2,2'-bipyridyl complexes [fac-Re(4,4'-di-COOEt-bpy) -(CO)3(Xpy)PF6], where bpy is 2,2'-bipyridine, py is pyridine and X is 3-methyl, 3-hydroxy, or 3-amino, were synthesized, their photophysical and electrochemical properties were studied. The Re(II/I) oxidation potentials decreased as the X group becomes more electron donating from H to 3-methyl, 3-hydroxy, or 3-amino, which might be a very convenient ways for adjusting the electron transfer driving force.
