The response to the catchment changes of the sedimentary environment of the western intertidal flat of Yalu River Estuary was investigated by analyzing the vertical variations of the grain size of sediment cores,along...The response to the catchment changes of the sedimentary environment of the western intertidal flat of Yalu River Estuary was investigated by analyzing the vertical variations of the grain size of sediment cores,along with the hydrologic data and human activities in the catchment.The results demonstrated a stepwise decreasing trend for the variations of both the sediment load and water discharge into the sea,which could be divided into three stages as 1958–1970,1971–1990 and 1991–2009.Reservoir construction and the changes of catchment vegetation coverage turned out to be the two predominant contributors to the changes.There are four periods for the variation of the sensitive components of the sediment cores from 1940 to 2010,i.e.,1940–1950,1951–1980,1981–1990 and 1991–2010.The vertical distribution of grain size in the cores mainly varied with the changes of vegetation coverage in the catchment and reservoir construction from 1960 to 1980,whereas it varied depending on the intensity of water and soil erosion in the catchment from 1980 to 1990.Despite the further reduction of the water and sediment input into the sea from 1990 to 2009,this period was characterized by coarsening trends for the grain size of sediment in the estuarine intertidal flat and correspondingly,the significantly increased silt contents of the sensitive component.展开更多
Sodium dual-ion batteries(SDIBs)based on organic active materials have attracted extensive attention due to their low cost,environmental friendliness,high safety,and superior stability.However,limitations such as poor...Sodium dual-ion batteries(SDIBs)based on organic active materials have attracted extensive attention due to their low cost,environmental friendliness,high safety,and superior stability.However,limitations such as poor conductivity,high solubility in electrolytes,kinetics constraints,and low active site utilization caused by dense layer stacking impede further advancement.Herein,a sawtooth polyimide anode with wide layer spacing,abundant active sites,and an extendedπ-conjugated system on nonplanar surfaces was designed through interlayer molecular engineering.The material exhibits a stable structure,fast transport and reaction kinetics,and high active-site utilization.Proof-of-concept SDIBs delivered a high discharge capacity of 162.4 mAh g^(-1)with 200 stable cycles without degradation,robust fast-charging capability,and a low self-discharge rate of 0.11%h^(-1).Excellent electrochemical performance with a reversible capacity of 107.6 mAh g^(-1),outstanding rate capability,low polarization,and 2000 stable cycles without attenuation were achieved even at high active mass loading.Mechanistic studies reveal a dualstorage mechanism involving diffusion and pseudocapacitance,expanding the diversity of redox-active polymers.These findings provide new insights and theoretical guidance to designing high-performance organic materials for Na+storage.展开更多
A dynamic divide-by-two regenerative GaP/GaAs heterojunction bipolar transistors （HBTs） frequency divider （RFD） is presented in a 60-GHz-fT Intechnology. To achieve high operation bandwidth, active loads instead o...A dynamic divide-by-two regenerative GaP/GaAs heterojunction bipolar transistors （HBTs） frequency divider （RFD） is presented in a 60-GHz-fT Intechnology. To achieve high operation bandwidth, active loads instead of resistor loads are incorporated into the RFD. On-wafer measurement shows that the divider is operating from 10 GHz up to at least 40 GHz, limited by the available input frequency. The maximum operation frequency of the divider is found to be much higher than fT/2 of the transistor, and also the divider has excellent input sensitivity. The divider consumes 300.85 mW from 5 V supply and occupies an area of 0.47 × 0.22 mm^2.展开更多
基金The National Natural Science Foundation of China under contract Nos 41576043 and 40976051
文摘The response to the catchment changes of the sedimentary environment of the western intertidal flat of Yalu River Estuary was investigated by analyzing the vertical variations of the grain size of sediment cores,along with the hydrologic data and human activities in the catchment.The results demonstrated a stepwise decreasing trend for the variations of both the sediment load and water discharge into the sea,which could be divided into three stages as 1958–1970,1971–1990 and 1991–2009.Reservoir construction and the changes of catchment vegetation coverage turned out to be the two predominant contributors to the changes.There are four periods for the variation of the sensitive components of the sediment cores from 1940 to 2010,i.e.,1940–1950,1951–1980,1981–1990 and 1991–2010.The vertical distribution of grain size in the cores mainly varied with the changes of vegetation coverage in the catchment and reservoir construction from 1960 to 1980,whereas it varied depending on the intensity of water and soil erosion in the catchment from 1980 to 1990.Despite the further reduction of the water and sediment input into the sea from 1990 to 2009,this period was characterized by coarsening trends for the grain size of sediment in the estuarine intertidal flat and correspondingly,the significantly increased silt contents of the sensitive component.
基金Fundamental and Applied Fundamental Research Project of Zhuhai City,Grant/Award Number:22017003200023National Natural Science Foundation of China,Grant/Award Number:22075089National Key Research and Development Program of China,Grant/Award Number:2024YFB4608600。
文摘Sodium dual-ion batteries(SDIBs)based on organic active materials have attracted extensive attention due to their low cost,environmental friendliness,high safety,and superior stability.However,limitations such as poor conductivity,high solubility in electrolytes,kinetics constraints,and low active site utilization caused by dense layer stacking impede further advancement.Herein,a sawtooth polyimide anode with wide layer spacing,abundant active sites,and an extendedπ-conjugated system on nonplanar surfaces was designed through interlayer molecular engineering.The material exhibits a stable structure,fast transport and reaction kinetics,and high active-site utilization.Proof-of-concept SDIBs delivered a high discharge capacity of 162.4 mAh g^(-1)with 200 stable cycles without degradation,robust fast-charging capability,and a low self-discharge rate of 0.11%h^(-1).Excellent electrochemical performance with a reversible capacity of 107.6 mAh g^(-1),outstanding rate capability,low polarization,and 2000 stable cycles without attenuation were achieved even at high active mass loading.Mechanistic studies reveal a dualstorage mechanism involving diffusion and pseudocapacitance,expanding the diversity of redox-active polymers.These findings provide new insights and theoretical guidance to designing high-performance organic materials for Na+storage.
基金supported by the National Basic Research Program of China(No.2010CBxxxx05)the Advance Research Project of China(No.51308xxxx06)the Advance Research Foundation of China(No.9140A08xxxx11DZ111)
文摘A dynamic divide-by-two regenerative GaP/GaAs heterojunction bipolar transistors （HBTs） frequency divider （RFD） is presented in a 60-GHz-fT Intechnology. To achieve high operation bandwidth, active loads instead of resistor loads are incorporated into the RFD. On-wafer measurement shows that the divider is operating from 10 GHz up to at least 40 GHz, limited by the available input frequency. The maximum operation frequency of the divider is found to be much higher than fT/2 of the transistor, and also the divider has excellent input sensitivity. The divider consumes 300.85 mW from 5 V supply and occupies an area of 0.47 × 0.22 mm^2.
