The geographical condition of Qingdao, China is relatively special;the transport of various inland pollutants, the emissions of marine aerosol and local pollutants will have an impact on the changes of atmospheric aer...The geographical condition of Qingdao, China is relatively special;the transport of various inland pollutants, the emissions of marine aerosol and local pollutants will have an impact on the changes of atmospheric aerosol concentration. By using the stability classification method, trajectory clustering analysis and the NOAA HYSPLIT model, the seasonal distribution characteristics of atmospheric inhalable particulate matter concentration in Qingdao, China and its relationship with meteorological conditions, mixed layer height, and the seasonal characteristics of Qingdao pollutant transport were analyzed. The results show that the variation trends of PM2.5 and PM10 were about the same, and there are obvious seasonal differences, which are high in winter and spring, and low in summer and autumn. The concentration of inhalable particulate matter has a negative correlation with temperature, wind speed and relative humidity. The concentration of inhalable particulate matter is distinct in different relative humidity ranges. When the wind speed is less than 3 - 4 m/s, there are more inhalable particles, while the mass concentration shows obvious reduction with the wind speed more than 4 m/s. There is a significant negative correlation between the mass concentration of pollutants and the daily maximum mixed layer height. The larger the concentration of pollutants, the smaller the thickness of the daily largest mixed layer. Conversely, the smaller the mass concentration of pollutants, the larger the thickness of the daily largest mixed layer. The pollutant transport in Qingdao has obvious seasonal characteristics. The air mass in spring, autumn and winter is mainly medium-long distance transport from Mongolia and southern Russia, and medium-short distance transport from Inner Mongolia and northeast of China. The source of air masses in summer is mainly transported from the eastern and sea areas.展开更多
Objective:To establish a gas chromatography-mass spectrometry(GC-MS)method for the determination of volatile components in different prepared products of Alisma purpurea.Methods:The volatile components were determined...Objective:To establish a gas chromatography-mass spectrometry(GC-MS)method for the determination of volatile components in different prepared products of Alisma purpurea.Methods:The volatile components were determined by GC-MS,and the types and relative contents of volatile components were compared in 4 kinds of processed products.Result:The main volatile components of 30 kinds of different products from Zelica were analyzed and identified,which were mainly sesquiterpenes,ketones and alcohols,mainly Pogostol,olive,guaiacene,caryophyllene and so on.Conclusion:There are differences in the types and relative contents of volatile components in different products of Alisma platyphylla,in order to provide a basis for improving the quality standards of different products of Alisma platyphylla.展开更多
In February 2019,a month-long persistent precipitation event occurred in the Yangtze–Huaihe River basin.The geopotential height field that affected the duration of this frontal rainfall was divided into a high-latitu...In February 2019,a month-long persistent precipitation event occurred in the Yangtze–Huaihe River basin.The geopotential height field that affected the duration of this frontal rainfall was divided into a high-latitude part and a lowlatitude part for analysis.In the high-latitude part,a two-wave structure led to quasi-stationary circulation,and the change of both the blocking high pressure and Arctic Oscillation phase caused cold air to invade South China continuously and changed the frontal position.In mid-to-low latitudes,the persistent precipitation showed quasi-biweekly oscillation characteristics.The so-called“subtropical high–precipitation–anticyclone”(SHPA)feedback mechanism blocked the circulation systems in the mid-to-low latitudes and provided a continuous supply of water vapor for precipitation.As for the effect of sea surface temperature,the western North Pacific anomalous anticyclone stimulated by El Niño strengthened the intensity of the southerly wind and provided support for the redevelopment of the anticyclone system in the SHPA feedback mechanism.The sea surface temperature anomaly in the South China Sea provided sensible heating for precipitation,and convergent rising airflow was conducive to the occurrence of precipitation.Additionally,the SHPA mechanism provides a reliable basis for the prediction of persistent precipitation in winter in the mid-to-low latitudes.展开更多
Reaxgen program for the pyrolysis mechanism of cycloalkanes was adopted to simulate the heat sink of substituted cyclohexanes. Thermal cracking of cyclohexanes was performed to examine the cracking performance, wherei...Reaxgen program for the pyrolysis mechanism of cycloalkanes was adopted to simulate the heat sink of substituted cyclohexanes. Thermal cracking of cyclohexanes was performed to examine the cracking performance, wherein the substituent effects were detailedly discussed under supercritical condition. It was found that Reaxgen program played a good part in the screening and optimization of cyclohexanes. A good agreement with the experimental data for the mono-substituted and bi-substituted cyclohexanes was demonstrated, however, some deviation for the tri-substituted cyclohexanes were observed. The experiment results indicated that the gaseous product yield increased sharply for mono- substituted cyclohexanes with short substituents containing no more than two carbons. Nevertheless, continuous increase in the alkyl chain depressed the gaseous product yield smoothly. The cyclic substituent dramatically inhibited the pyrolysis of cyclohexanes. All the substituents but cyclohexyl had no obvious effect on the yield of hydrogen and olefins （≤C4）. For bi-substituted cyclohexanes, the more close the distance between the two substituents, the higher the gaseous product yield was obtained. However, opposite result on the selectivity to hydrogen and olefins （≤C4） was generally obtained except 1,3-dimethylcyclohexane. The position of tri-substituents acted little significance on the gaseous product yield, as well as the selectivity to hydrogen and olefins （≤C4）.展开更多
Photothermal ethanol steam reforming(ESR) is currently limited by low intrinsic activity and strong solar energy dissipation.Herein,we synthesized Fe single atoms supported on CeO_(2)(SA Fe-CeO_(2)) to exhibit excelle...Photothermal ethanol steam reforming(ESR) is currently limited by low intrinsic activity and strong solar energy dissipation.Herein,we synthesized Fe single atoms supported on CeO_(2)(SA Fe-CeO_(2)) to exhibit excellent low-temperature ESR activity with a hydrogen production rate of 512 mmol g^(-1)h^(-1) at 350℃,becuase of the high oxidation state of Fe single atoms to weaken the reaction barrier of ethanol decomposition.Furthermore,a heterostructure of SA Fe-CeO_(2) and Ti foil could eliminate 66% of infrared radiation via the size effect,thus achieving a 3.5 sun-driven temperature of 347℃.Consequently,the heterostructure of SA Fe-CeO_(2) and Ti foil shows a hydrogen generation rate of 984 mmol g^(-1)h^(-1) of ESR and 11.31% of solar-to-hydrogen energy conversion efficiency,which outperforms other photothermal ethanol-hydrogen production systems.This study provides a new path for designing active catalytic sites and trapping light energy of photothermal catalysts.展开更多
Rapid development of online economy has great impact on the everyday life.However,whether real space still matter on the location choice of these new economies remains as a controversial question.This research starts ...Rapid development of online economy has great impact on the everyday life.However,whether real space still matter on the location choice of these new economies remains as a controversial question.This research starts with spatial analysis on shared kitchen as an emerging new type of online catering space in Beijing across three scales:city,street,architecture.Using social media data and cellular signal data,different density factors are tested at city scale to explain the performance of these economies.Using space syntax model,the spatial accessibility of takeaway only,dine-in with takeaway service and conventional restaurants are compared in central and suburban areas.It is found that their different spatial logic:at city scale,takeaway only restaurants gathered in the high-density area,and diffused to the area with poor accessibility.At street and architectural scale,online catering in general shows higher dependence on accessibility,but there is a clear difference between central and suburban cases of takeaway only restaurants:in central areas,online catering could bear more disadvantageous positions like backstreet or under the ground of buildings than it in suburban case.展开更多
Sulfide-based all-solid-state lithium-ion batteries(ASSLIBs)are one of the most promising energy storage technologies due to their high safety and ionic conductivity.To achieve greater energy density,a Ni-rich layered...Sulfide-based all-solid-state lithium-ion batteries(ASSLIBs)are one of the most promising energy storage technologies due to their high safety and ionic conductivity.To achieve greater energy density,a Ni-rich layered oxide LiNi_(x)Co_(y)M_(1-x-y)O_(2)(NCM,MMn/Al,x≥0.6)is desirable due to its relatively high voltage and large capacity.However,interfacial side reactions between the NCM and sulfide solid electrolytes lead to undesirable interfacial passivation layers and low ionic conductivity,thereby degrading the electrochemical performance of NCM sulfide all-solid-state batteries.Herein,a time-/cost-effective sulfidation strategy is exploited to sulfidize a Ni-rich NCM_(88) cathode in a mixed gas atmosphere of N_(2) and CS_(2).A new type of cathode(NCM88-S)with an ultrathin(∼2nm)surface layer is obtained,which significantly reduces the interfacial side reactions/resistance and improves the interfacial stability.The resulting NCM_(88)-S/Li_(6)PS_(5)Cl/Li_(4)Ti_(5)O_(12) ASSLIB exhibits superior performance,including a high discharge specific capacity(200.7 mAh g−1)close to that of liquid batteries,excellent cycling performance(a capacity retention of 87%after 500 cycles),and satisfactory rate performance(158.3 mAh g^(−1) at 1C).展开更多
文摘The geographical condition of Qingdao, China is relatively special;the transport of various inland pollutants, the emissions of marine aerosol and local pollutants will have an impact on the changes of atmospheric aerosol concentration. By using the stability classification method, trajectory clustering analysis and the NOAA HYSPLIT model, the seasonal distribution characteristics of atmospheric inhalable particulate matter concentration in Qingdao, China and its relationship with meteorological conditions, mixed layer height, and the seasonal characteristics of Qingdao pollutant transport were analyzed. The results show that the variation trends of PM2.5 and PM10 were about the same, and there are obvious seasonal differences, which are high in winter and spring, and low in summer and autumn. The concentration of inhalable particulate matter has a negative correlation with temperature, wind speed and relative humidity. The concentration of inhalable particulate matter is distinct in different relative humidity ranges. When the wind speed is less than 3 - 4 m/s, there are more inhalable particles, while the mass concentration shows obvious reduction with the wind speed more than 4 m/s. There is a significant negative correlation between the mass concentration of pollutants and the daily maximum mixed layer height. The larger the concentration of pollutants, the smaller the thickness of the daily largest mixed layer. Conversely, the smaller the mass concentration of pollutants, the larger the thickness of the daily largest mixed layer. The pollutant transport in Qingdao has obvious seasonal characteristics. The air mass in spring, autumn and winter is mainly medium-long distance transport from Mongolia and southern Russia, and medium-short distance transport from Inner Mongolia and northeast of China. The source of air masses in summer is mainly transported from the eastern and sea areas.
文摘Objective:To establish a gas chromatography-mass spectrometry(GC-MS)method for the determination of volatile components in different prepared products of Alisma purpurea.Methods:The volatile components were determined by GC-MS,and the types and relative contents of volatile components were compared in 4 kinds of processed products.Result:The main volatile components of 30 kinds of different products from Zelica were analyzed and identified,which were mainly sesquiterpenes,ketones and alcohols,mainly Pogostol,olive,guaiacene,caryophyllene and so on.Conclusion:There are differences in the types and relative contents of volatile components in different products of Alisma platyphylla,in order to provide a basis for improving the quality standards of different products of Alisma platyphylla.
基金We gratefully acknowledge support from the State Key Program of the National Natural Science Foundation of China(Grant No.41430963).
文摘In February 2019,a month-long persistent precipitation event occurred in the Yangtze–Huaihe River basin.The geopotential height field that affected the duration of this frontal rainfall was divided into a high-latitude part and a lowlatitude part for analysis.In the high-latitude part,a two-wave structure led to quasi-stationary circulation,and the change of both the blocking high pressure and Arctic Oscillation phase caused cold air to invade South China continuously and changed the frontal position.In mid-to-low latitudes,the persistent precipitation showed quasi-biweekly oscillation characteristics.The so-called“subtropical high–precipitation–anticyclone”(SHPA)feedback mechanism blocked the circulation systems in the mid-to-low latitudes and provided a continuous supply of water vapor for precipitation.As for the effect of sea surface temperature,the western North Pacific anomalous anticyclone stimulated by El Niño strengthened the intensity of the southerly wind and provided support for the redevelopment of the anticyclone system in the SHPA feedback mechanism.The sea surface temperature anomaly in the South China Sea provided sensible heating for precipitation,and convergent rising airflow was conducive to the occurrence of precipitation.Additionally,the SHPA mechanism provides a reliable basis for the prediction of persistent precipitation in winter in the mid-to-low latitudes.
基金supported by the Special Program for Key Basic Research in China(Grant No.0040202204)
文摘Reaxgen program for the pyrolysis mechanism of cycloalkanes was adopted to simulate the heat sink of substituted cyclohexanes. Thermal cracking of cyclohexanes was performed to examine the cracking performance, wherein the substituent effects were detailedly discussed under supercritical condition. It was found that Reaxgen program played a good part in the screening and optimization of cyclohexanes. A good agreement with the experimental data for the mono-substituted and bi-substituted cyclohexanes was demonstrated, however, some deviation for the tri-substituted cyclohexanes were observed. The experiment results indicated that the gaseous product yield increased sharply for mono- substituted cyclohexanes with short substituents containing no more than two carbons. Nevertheless, continuous increase in the alkyl chain depressed the gaseous product yield smoothly. The cyclic substituent dramatically inhibited the pyrolysis of cyclohexanes. All the substituents but cyclohexyl had no obvious effect on the yield of hydrogen and olefins （≤C4）. For bi-substituted cyclohexanes, the more close the distance between the two substituents, the higher the gaseous product yield was obtained. However, opposite result on the selectivity to hydrogen and olefins （≤C4） was generally obtained except 1,3-dimethylcyclohexane. The position of tri-substituents acted little significance on the gaseous product yield, as well as the selectivity to hydrogen and olefins （≤C4）.
基金supported by the National Natural Science Foundation of China(Grant No.52371220)Natural Science Foundation of Hebei Province(Grant Nos.B2023204034,B2023201107,B2022201090,B2021201074,B2021201034,F2021203097)+5 种基金Hebei Provincial Department of Science and Technology(Grant No.216Z4303G)Hebei Education Department(Grant No,QN2022059)Interdisciplinary Research Program of Natural Science of Hebei University(Grant Nos.521100311,DXK202109)the Advanced Talents Incubation Program of Hebei University(Grant Nos.521100223213,521000981248,521000981377 and 8012605)Hebei University(050001-521100302025,050001-513300201004)the Scientific Research Foundation of Hebei Agricultural University(YJ201939)。
文摘Photothermal ethanol steam reforming(ESR) is currently limited by low intrinsic activity and strong solar energy dissipation.Herein,we synthesized Fe single atoms supported on CeO_(2)(SA Fe-CeO_(2)) to exhibit excellent low-temperature ESR activity with a hydrogen production rate of 512 mmol g^(-1)h^(-1) at 350℃,becuase of the high oxidation state of Fe single atoms to weaken the reaction barrier of ethanol decomposition.Furthermore,a heterostructure of SA Fe-CeO_(2) and Ti foil could eliminate 66% of infrared radiation via the size effect,thus achieving a 3.5 sun-driven temperature of 347℃.Consequently,the heterostructure of SA Fe-CeO_(2) and Ti foil shows a hydrogen generation rate of 984 mmol g^(-1)h^(-1) of ESR and 11.31% of solar-to-hydrogen energy conversion efficiency,which outperforms other photothermal ethanol-hydrogen production systems.This study provides a new path for designing active catalytic sites and trapping light energy of photothermal catalysts.
文摘Rapid development of online economy has great impact on the everyday life.However,whether real space still matter on the location choice of these new economies remains as a controversial question.This research starts with spatial analysis on shared kitchen as an emerging new type of online catering space in Beijing across three scales:city,street,architecture.Using social media data and cellular signal data,different density factors are tested at city scale to explain the performance of these economies.Using space syntax model,the spatial accessibility of takeaway only,dine-in with takeaway service and conventional restaurants are compared in central and suburban areas.It is found that their different spatial logic:at city scale,takeaway only restaurants gathered in the high-density area,and diffused to the area with poor accessibility.At street and architectural scale,online catering in general shows higher dependence on accessibility,but there is a clear difference between central and suburban cases of takeaway only restaurants:in central areas,online catering could bear more disadvantageous positions like backstreet or under the ground of buildings than it in suburban case.
基金supported by Key Program-Automobile Joint Fund of National Natural Science Foundation of China(Grant No.U1964205),Key R&D Project funded by Department of Science and Technology of Jiangsu Province(Grant No.BE2020003),General Program of National Natural Science Foundation of China(Grant No.51972334),General Program of National Natural Science Foundation of Beijing(Grant No.2202058),Cultivation project of leading innovative experts in Changzhou City(CQ20210003),National Overseas High-level Expert recruitment Program(Grant No.E1JF021E11),Talent Program of Chinese Academy of Sciences,“Scientist Studio Program Funding”from Yangtze River Delta Physics Research Center and Tianmu Lake Institute of Advanced Energy Storage Technologies(Grant No.TIES-SS0001).Science and Technology Research Institute of China Three Gorges Corporation(Grant 202103402).
文摘Sulfide-based all-solid-state lithium-ion batteries(ASSLIBs)are one of the most promising energy storage technologies due to their high safety and ionic conductivity.To achieve greater energy density,a Ni-rich layered oxide LiNi_(x)Co_(y)M_(1-x-y)O_(2)(NCM,MMn/Al,x≥0.6)is desirable due to its relatively high voltage and large capacity.However,interfacial side reactions between the NCM and sulfide solid electrolytes lead to undesirable interfacial passivation layers and low ionic conductivity,thereby degrading the electrochemical performance of NCM sulfide all-solid-state batteries.Herein,a time-/cost-effective sulfidation strategy is exploited to sulfidize a Ni-rich NCM_(88) cathode in a mixed gas atmosphere of N_(2) and CS_(2).A new type of cathode(NCM88-S)with an ultrathin(∼2nm)surface layer is obtained,which significantly reduces the interfacial side reactions/resistance and improves the interfacial stability.The resulting NCM_(88)-S/Li_(6)PS_(5)Cl/Li_(4)Ti_(5)O_(12) ASSLIB exhibits superior performance,including a high discharge specific capacity(200.7 mAh g−1)close to that of liquid batteries,excellent cycling performance(a capacity retention of 87%after 500 cycles),and satisfactory rate performance(158.3 mAh g^(−1) at 1C).
