Fine particulate matter(PM_(2.5))and ozone(O_(3))double high pollution(DHP)events have occurred frequently over China in recent years,but their causes are not completely clear.In this study,the spatiotemporal distribu...Fine particulate matter(PM_(2.5))and ozone(O_(3))double high pollution(DHP)events have occurred frequently over China in recent years,but their causes are not completely clear.In this study,the spatiotemporal distribution of DHP events in China during 2013–20 is analyzed.The synoptic types affecting DHP events are identified with the Lamb–Jenkinson circulation classification method.The meteorological and chemical causes of DHP events controlled by the main synoptic types are further investigated.Results show that DHP events(1655 in total for China during 2013–20)mainly occur over the North China Plain,Yangtze River Delta,Pearl River Delta,Sichuan Basin,and Central China.The occurrence frequency increases by 5.1%during 2013–15,and then decreases by 56.1%during 2015–20.The main circulation types of DHP events are“cyclone”and“anticyclone”,accounting for over 40%of all DHP events over five main polluted regions in China,followed by southerly or easterly flat airflow types,like“southeast”,“southwest”,and“east”.Compared with non-DHP events,DHP events are characterized by static or weak wind,high temperature(20.9℃ versus 23.1℃)and low humidity(70.0%versus 64.9%).The diurnal cycles of meteorological conditions cause PM_(2.5)(0300–1200 LST,Local Standard Time=UTC+8 hours)and O_(3)(1500–2100 LST)to exceed the national standards at different periods of the DHP day.Three pollutant conversion indices further indicate the rapid secondary conversions during DHP events,and thus the concentrations of NO_(2),SO_(2) and volatile organic compounds decrease by 13.1%,4.7%and 4.4%,respectively.The results of this study can be informative for future decisions on the management of DHP events.展开更多
Using the observed data from 184 stations over the Yunnan-Guizhou Plateau (YGP) from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility (Vd), dry extinction, and water vapor over...Using the observed data from 184 stations over the Yunnan-Guizhou Plateau (YGP) from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility (Vd), dry extinction, and water vapor over the YGP are analyzed. The results show that 85% of the stations recorded shortening annual sunshine duration, with the decrease rates between -12.2 and -173.7 h/10yr. Results of Mann-Kendall tests indicate that, among the stations with decreasing sunshine duration, 63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s. This decreasing trend has reversed in the early years of the 21st century. The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period. The annual averages of Vd declined from 34 km in the 1960s to 27 km at present. The annual mean dry extinction coefficient trended upward, from 0.176 to 0.190, on the YGP from 1980 to 2005. Analyses of cloud cover, water vapor, atmospheric visibility, and dry extinction coefficient revealed that emitted tropospheric aerosols (including air pollutants) resulting from increased energy consumption over the YGP could be a major Factor influencing the reductions of sunshine duration and atmospheric visibility.展开更多
Objective: To investigate the effect of docetaxel and cisplatin combined with intensity-modulated radiotherapy in thetreatment of postoperative recurrence of esophageal cancer and the content of tumor markers in serum...Objective: To investigate the effect of docetaxel and cisplatin combined with intensity-modulated radiotherapy in thetreatment of postoperative recurrence of esophageal cancer and the content of tumor markers in serum. Methods: According tosimple randomization method, 60 patients with postoperative recurrence of esophageal cancer admitted from February 2018 toSeptember 2019 were divided into control group (n = 30 cases) and observation group (n = 30 cases). All patients received IMRT.Fluorouracil + cisplatin was used in the control group and docetaxel + cisplatin was used in the observation group. After 2 coursesof continuous treatment, the therapeutic effect, serum tumor marker content and adverse reactions were compared between thetwo groups. Results: After treatment, the effective rate of observation group was higher than control group, and the difference wasstatistically significant (P < 0.05).The contents of carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC) andcarbohydrate antigen 19-9 (CA19-9) in observation group were lower than those in control group, and the difference was statisticallysignificant (P < 0.05). The incidence of adverse reactions in the observation group was lower than that in the control group, and thedifference was statistically significant (P < 0.05). Conclusion: Docetaxel and cisplatin combined with intensemodulated radiotherapyfor postoperative recurrence of esophageal cancer can improve the therapeutic effect, inhibit the malignant degree of tumor, andreduce the incidence of adverse reactions.展开更多
The role of PM_(2.5)(particles with aerodynamic diameters≤_(2.5)μm)deposition in air quality changes over China remains unclear.By using the three-year(2013,2015,and 2017)simulation results of the WRF/CUACE v1.0 mod...The role of PM_(2.5)(particles with aerodynamic diameters≤_(2.5)μm)deposition in air quality changes over China remains unclear.By using the three-year(2013,2015,and 2017)simulation results of the WRF/CUACE v1.0 model from a previous work(Zhang et al.,2021),a non-linear relationship between the deposition of PM_(2.5)and anthropogenic emissions over central-eastern China in cold seasons as well as in different life stages of haze events was unraveled.PM_(2.5)deposition is spatially distributed differently from PM_(2.5)concentrations and anthropogenic emissions over China.The North China Plain(NCP)is typically characterized by higher anthropogenic emissions compared to southern China,such as the middlelow reaches of Yangtze River(MLYR),which includes parts of the Yangtze River Delta and the Midwest.However,PM_(2.5)deposition in the NCP is significantly lower than that in the MLYR region,suggesting that in addition to meteorology and emissions,lower deposition is another important factor in the increase in haze levels.Regional transport of pollution in central-eastern China acts as a moderator of pollution levels in different regions,for example by bringing pollution from the NCP to the MLYR region in cold seasons.It was found that in typical haze events the deposition flux of PM_(2.5)during the removal stages is substantially higher than that in accumulation stages,with most of the PM_(2.5)being transported southward and deposited to the MLYR and Sichuan Basin region,corresponding to a latitude range of about 24°N-31°N.展开更多
The effect of Mo content on the microstructure revolution and corrosion behavior of cast FeCoCrNiMox high-entropy alloys in chloride environments were investigated.Results indicate that FeCoCrNi and FeCoCrNiMo0.1 allo...The effect of Mo content on the microstructure revolution and corrosion behavior of cast FeCoCrNiMox high-entropy alloys in chloride environments were investigated.Results indicate that FeCoCrNi and FeCoCrNiMo0.1 alloys are in single FCC solid solution.The precipitates form in FeCoCrNiMo0.3 and increase in FeCoCrNiMo0.6 alloys.Pitting occurs on FeCoCrNi and FeCoCrNiMo0.1 alloys while FeCoCrNiMo0.3 and FeCoCrNiMo0.6 alloys suffer from preferential localized corrosion at the regions depleted in Cr and Mo.The higher Cr2O3/Cr(OH)3 ratio and the incorporation of Mo oxides make the passive film more protective and the corrosion resistance of the FeCoCrNiMo0.1 alloy is thus enhanced.The correlation between microstructure and corrosion behavior and the corresponding corrosion mechanism were clarified.展开更多
To control the spread of COVID-19,rigorous restrictions have been implemented in China,resulting in a great reduction in pollutant emissions.In this study,we evaluated the air quality in the Yangtze River Delta during...To control the spread of COVID-19,rigorous restrictions have been implemented in China,resulting in a great reduction in pollutant emissions.In this study,we evaluated the air quality in the Yangtze River Delta during the COVID-19 lockdown period using satellite and ground-based data,including particle matter(PM),trace gases,water-soluble ions(WSIs) and black carbon(BC).We found that the impacts of lockdown policy on air quality cannot be accurately assessed using MODIS aerosol optical depth(AOD) data,whereas the tropospheric nitrogen dioxide(NO_(2)) vertical column density can well reflect the influences of these restrictions on human activities.Compared to the pre-COVID period,the PM_(2.5),PM_(10),NO_(2),carbon monoxide(CO),BC and WSIs during the lockdown in Suzhou were observed to decrease by 37.2%,38.3%,64.5%,26.1%,53.3% and 58.6%,respectively,while the sulfur dioxide(SO_(2)) and ozone(O_(3)) increased by 1.5% and 104.7%.The WSIs ranked in the order of NO_(3)~->NH_(4)^(+)>SO_(4)^(2-)>Cl~->Ca^(2+)>K^(+)>Mg^(2+)>Na + during the lockdown period.By comparisons with the ion concentrations during the pre-COVID period,we found that the ions NO 3-,NH 4 +,SO_(4)^(2-),Cl~-,Ca^(2+),K^(+) and Na^(+) decreased by 66.3%,48.8%,52.9%,56.9%,57.9% and 76.3%,respectively,during the lockdown,in contrast to Mg^(2+),which increased by 30.2%.The lockdown policy was found to have great impacts on the diurnal variations of Cl~-,SO_(4)^(2-),Na^(+) and Ca^(2+).展开更多
The optical and radiative properties of aerosols during a severe haze episode from 15 to 22 December 2016 over Beijing, Shijiazhuang, and Jiaozuo in the North China Plain were analyzed based on the ground-based and sa...The optical and radiative properties of aerosols during a severe haze episode from 15 to 22 December 2016 over Beijing, Shijiazhuang, and Jiaozuo in the North China Plain were analyzed based on the ground-based and satellite data, meteorological observations, and atmospheric environmental monitoring data. The aerosol optical depth at 500 nm was 〈 0.30 and increased to 〉 1.4 as the haze pollution developed. The Angstr6m exponent was 〉 0.80 for most of the study period. The daily single-scattering albedo was 〉 0.85 over all of the North China Plain on the most polluted days and was 〉 0.97 on some particular days. The volumes of fine and coarse mode particles during the haze event were approximately 0.05-0.21 and 0.01-0.43 μm^3, respectively-that is, larger than those in the time without haze. The daily absorption aerosol optical depth was about 0.01-0.11 in Beijing, 0.01-0.13 in Shijiazhuang, and 0.01-0.04 in Jiaozuo, and the average absorption Angstrom exponent varied between 0.6 and 2.0. The aerosol radiative forcing at the bottom of the atmosphere varied from -23 to -227, -34 to -199, and -29 to -191 W m^-2 for the whole haze period, while the aerosol radiative forcing at the top of the atmosphere varied from -4 to -98, -10 to -51, and -21 to -143 W m^-2 in Beijing, Shijiazhuang, and Jiaozuo, respectively. Satellite observations showed that smoke, polluted dust, and polluted continental components of aerosols may aggravate air pollution during haze episodes. The analysis of the potential source contribution function and concentration-weighted trajectory showed that the contribu- tion from local emissions and pollutants transport from upstream areas were 190-450 and 100-410 btg m-3, respectively.展开更多
The Asian monsoon(AM) region is a well-known region with prevailing stratosphere–troposphere exchange(STE).However,how the STE across this region changes with the weakening AM remains unclear.Here,we particularly dia...The Asian monsoon(AM) region is a well-known region with prevailing stratosphere–troposphere exchange(STE).However,how the STE across this region changes with the weakening AM remains unclear.Here,we particularly diagnose the air mass transport between the planetary boundary layer(PBL) and the stratosphere over the AM region during 1992–2017 using the Lagrangian particle dispersion model FLEXPART based on the ERA-Interim reanalysis data.The results show that both the downward and upward deep STEs exhibit a detectable increasing trend,while the latter,namely,the deep troposphere-to-stratosphere transport(DTST),is relatively more significant.Further analysis reveals that the long-term trend of DTST over the AM region could be partly attributed to changes in the Pacific Walker circulation and the air temperature(especially at upper levels).Additionally,it is found that DTST increases markedly over the tropical oceanic regions,while the increasing DTST into the stratosphere can be attributed to the enhanced air masses originated from the PBL over the terrestrial regions,where large amounts of pollutant emissions occur.The results imply that the influence of the DTST on the chemical composition and the climate of the stratosphere over the AM region is expected to become increasingly important,and is thereby of relevance to climate projection in an evolving climate.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41830965 and 41905112)the Key Program of the Ministry of Science and Technology of the People’s Republic of China(Grant No.2019YFC0214703)+2 种基金the Hubei Natural Science Foundation(Grant No.2022CFB027)supported by the State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry(Grant No.LAPC-KF-2023-07)the Key Laboratory of Atmospheric Chemistry,China Meteorological Administration(Grant No.2023B08).
文摘Fine particulate matter(PM_(2.5))and ozone(O_(3))double high pollution(DHP)events have occurred frequently over China in recent years,but their causes are not completely clear.In this study,the spatiotemporal distribution of DHP events in China during 2013–20 is analyzed.The synoptic types affecting DHP events are identified with the Lamb–Jenkinson circulation classification method.The meteorological and chemical causes of DHP events controlled by the main synoptic types are further investigated.Results show that DHP events(1655 in total for China during 2013–20)mainly occur over the North China Plain,Yangtze River Delta,Pearl River Delta,Sichuan Basin,and Central China.The occurrence frequency increases by 5.1%during 2013–15,and then decreases by 56.1%during 2015–20.The main circulation types of DHP events are“cyclone”and“anticyclone”,accounting for over 40%of all DHP events over five main polluted regions in China,followed by southerly or easterly flat airflow types,like“southeast”,“southwest”,and“east”.Compared with non-DHP events,DHP events are characterized by static or weak wind,high temperature(20.9℃ versus 23.1℃)and low humidity(70.0%versus 64.9%).The diurnal cycles of meteorological conditions cause PM_(2.5)(0300–1200 LST,Local Standard Time=UTC+8 hours)and O_(3)(1500–2100 LST)to exceed the national standards at different periods of the DHP day.Three pollutant conversion indices further indicate the rapid secondary conversions during DHP events,and thus the concentrations of NO_(2),SO_(2) and volatile organic compounds decrease by 13.1%,4.7%and 4.4%,respectively.The results of this study can be informative for future decisions on the management of DHP events.
基金funded by the National Natural Science Foundation of China (NSFC) (Grant No. 40965009)the Guizhou Provincial Meteorological Bureau Key Laboratory Programme (No. KF200906)
文摘Using the observed data from 184 stations over the Yunnan-Guizhou Plateau (YGP) from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility (Vd), dry extinction, and water vapor over the YGP are analyzed. The results show that 85% of the stations recorded shortening annual sunshine duration, with the decrease rates between -12.2 and -173.7 h/10yr. Results of Mann-Kendall tests indicate that, among the stations with decreasing sunshine duration, 63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s. This decreasing trend has reversed in the early years of the 21st century. The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period. The annual averages of Vd declined from 34 km in the 1960s to 27 km at present. The annual mean dry extinction coefficient trended upward, from 0.176 to 0.190, on the YGP from 1980 to 2005. Analyses of cloud cover, water vapor, atmospheric visibility, and dry extinction coefficient revealed that emitted tropospheric aerosols (including air pollutants) resulting from increased energy consumption over the YGP could be a major Factor influencing the reductions of sunshine duration and atmospheric visibility.
文摘Objective: To investigate the effect of docetaxel and cisplatin combined with intensity-modulated radiotherapy in thetreatment of postoperative recurrence of esophageal cancer and the content of tumor markers in serum. Methods: According tosimple randomization method, 60 patients with postoperative recurrence of esophageal cancer admitted from February 2018 toSeptember 2019 were divided into control group (n = 30 cases) and observation group (n = 30 cases). All patients received IMRT.Fluorouracil + cisplatin was used in the control group and docetaxel + cisplatin was used in the observation group. After 2 coursesof continuous treatment, the therapeutic effect, serum tumor marker content and adverse reactions were compared between thetwo groups. Results: After treatment, the effective rate of observation group was higher than control group, and the difference wasstatistically significant (P < 0.05).The contents of carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC) andcarbohydrate antigen 19-9 (CA19-9) in observation group were lower than those in control group, and the difference was statisticallysignificant (P < 0.05). The incidence of adverse reactions in the observation group was lower than that in the control group, and thedifference was statistically significant (P < 0.05). Conclusion: Docetaxel and cisplatin combined with intensemodulated radiotherapyfor postoperative recurrence of esophageal cancer can improve the therapeutic effect, inhibit the malignant degree of tumor, andreduce the incidence of adverse reactions.
基金supported by the National Key Foundation Study Developing Programs(Nos.2019YFC0214801 and 2019YFC0214601)the National Natural Science Foundation of China(Nos.42090030,41975131 and 91744209)the CAMS Basic Research Project(No.2020Y001)。
文摘The role of PM_(2.5)(particles with aerodynamic diameters≤_(2.5)μm)deposition in air quality changes over China remains unclear.By using the three-year(2013,2015,and 2017)simulation results of the WRF/CUACE v1.0 model from a previous work(Zhang et al.,2021),a non-linear relationship between the deposition of PM_(2.5)and anthropogenic emissions over central-eastern China in cold seasons as well as in different life stages of haze events was unraveled.PM_(2.5)deposition is spatially distributed differently from PM_(2.5)concentrations and anthropogenic emissions over China.The North China Plain(NCP)is typically characterized by higher anthropogenic emissions compared to southern China,such as the middlelow reaches of Yangtze River(MLYR),which includes parts of the Yangtze River Delta and the Midwest.However,PM_(2.5)deposition in the NCP is significantly lower than that in the MLYR region,suggesting that in addition to meteorology and emissions,lower deposition is another important factor in the increase in haze levels.Regional transport of pollution in central-eastern China acts as a moderator of pollution levels in different regions,for example by bringing pollution from the NCP to the MLYR region in cold seasons.It was found that in typical haze events the deposition flux of PM_(2.5)during the removal stages is substantially higher than that in accumulation stages,with most of the PM_(2.5)being transported southward and deposited to the MLYR and Sichuan Basin region,corresponding to a latitude range of about 24°N-31°N.
基金the National Material Environmental Corrosion infrastructurethe State Key Laboratory for Advanced Metals and Materials(No.2018Z-05)。
文摘The effect of Mo content on the microstructure revolution and corrosion behavior of cast FeCoCrNiMox high-entropy alloys in chloride environments were investigated.Results indicate that FeCoCrNi and FeCoCrNiMo0.1 alloys are in single FCC solid solution.The precipitates form in FeCoCrNiMo0.3 and increase in FeCoCrNiMo0.6 alloys.Pitting occurs on FeCoCrNi and FeCoCrNiMo0.1 alloys while FeCoCrNiMo0.3 and FeCoCrNiMo0.6 alloys suffer from preferential localized corrosion at the regions depleted in Cr and Mo.The higher Cr2O3/Cr(OH)3 ratio and the incorporation of Mo oxides make the passive film more protective and the corrosion resistance of the FeCoCrNiMo0.1 alloy is thus enhanced.The correlation between microstructure and corrosion behavior and the corresponding corrosion mechanism were clarified.
基金supported by the National Natural Science Foundation of China (Nos.91644224,41805096)the National Key Research and Development Program of China (No.2016YFA0602003)+1 种基金the China Postdoctoral Science Foundation (No.2018M640169)the Natural Science Research Project for Universities of Jiangsu Province,China (No.18KJB170011)。
文摘To control the spread of COVID-19,rigorous restrictions have been implemented in China,resulting in a great reduction in pollutant emissions.In this study,we evaluated the air quality in the Yangtze River Delta during the COVID-19 lockdown period using satellite and ground-based data,including particle matter(PM),trace gases,water-soluble ions(WSIs) and black carbon(BC).We found that the impacts of lockdown policy on air quality cannot be accurately assessed using MODIS aerosol optical depth(AOD) data,whereas the tropospheric nitrogen dioxide(NO_(2)) vertical column density can well reflect the influences of these restrictions on human activities.Compared to the pre-COVID period,the PM_(2.5),PM_(10),NO_(2),carbon monoxide(CO),BC and WSIs during the lockdown in Suzhou were observed to decrease by 37.2%,38.3%,64.5%,26.1%,53.3% and 58.6%,respectively,while the sulfur dioxide(SO_(2)) and ozone(O_(3)) increased by 1.5% and 104.7%.The WSIs ranked in the order of NO_(3)~->NH_(4)^(+)>SO_(4)^(2-)>Cl~->Ca^(2+)>K^(+)>Mg^(2+)>Na + during the lockdown period.By comparisons with the ion concentrations during the pre-COVID period,we found that the ions NO 3-,NH 4 +,SO_(4)^(2-),Cl~-,Ca^(2+),K^(+) and Na^(+) decreased by 66.3%,48.8%,52.9%,56.9%,57.9% and 76.3%,respectively,during the lockdown,in contrast to Mg^(2+),which increased by 30.2%.The lockdown policy was found to have great impacts on the diurnal variations of Cl~-,SO_(4)^(2-),Na^(+) and Ca^(2+).
基金Supported by the National Key R&D Program(2016YFC0203306 and 2016YFA0601901)National Natural Science Foundation of China(41401403,41590874,and 41375153)+1 种基金Key Technology R&D Program of Henan Province(162102310089)Basic Research Project of Chinese Academy of Meteorological Sciences(2016Z001 and 2014R17)
文摘The optical and radiative properties of aerosols during a severe haze episode from 15 to 22 December 2016 over Beijing, Shijiazhuang, and Jiaozuo in the North China Plain were analyzed based on the ground-based and satellite data, meteorological observations, and atmospheric environmental monitoring data. The aerosol optical depth at 500 nm was 〈 0.30 and increased to 〉 1.4 as the haze pollution developed. The Angstr6m exponent was 〉 0.80 for most of the study period. The daily single-scattering albedo was 〉 0.85 over all of the North China Plain on the most polluted days and was 〉 0.97 on some particular days. The volumes of fine and coarse mode particles during the haze event were approximately 0.05-0.21 and 0.01-0.43 μm^3, respectively-that is, larger than those in the time without haze. The daily absorption aerosol optical depth was about 0.01-0.11 in Beijing, 0.01-0.13 in Shijiazhuang, and 0.01-0.04 in Jiaozuo, and the average absorption Angstrom exponent varied between 0.6 and 2.0. The aerosol radiative forcing at the bottom of the atmosphere varied from -23 to -227, -34 to -199, and -29 to -191 W m^-2 for the whole haze period, while the aerosol radiative forcing at the top of the atmosphere varied from -4 to -98, -10 to -51, and -21 to -143 W m^-2 in Beijing, Shijiazhuang, and Jiaozuo, respectively. Satellite observations showed that smoke, polluted dust, and polluted continental components of aerosols may aggravate air pollution during haze episodes. The analysis of the potential source contribution function and concentration-weighted trajectory showed that the contribu- tion from local emissions and pollutants transport from upstream areas were 190-450 and 100-410 btg m-3, respectively.
基金Supported by the National Key Research and Development Program of China (2023YFC3010700)Second Tibetan Plateau Comprehensive Scientific Expedition and Research Program (2019QZKK0105)Science and Technology Development Fund of Chinese Academy of Meteorological Sciences (2023KJ027 and 2024KJ012)。
文摘The Asian monsoon(AM) region is a well-known region with prevailing stratosphere–troposphere exchange(STE).However,how the STE across this region changes with the weakening AM remains unclear.Here,we particularly diagnose the air mass transport between the planetary boundary layer(PBL) and the stratosphere over the AM region during 1992–2017 using the Lagrangian particle dispersion model FLEXPART based on the ERA-Interim reanalysis data.The results show that both the downward and upward deep STEs exhibit a detectable increasing trend,while the latter,namely,the deep troposphere-to-stratosphere transport(DTST),is relatively more significant.Further analysis reveals that the long-term trend of DTST over the AM region could be partly attributed to changes in the Pacific Walker circulation and the air temperature(especially at upper levels).Additionally,it is found that DTST increases markedly over the tropical oceanic regions,while the increasing DTST into the stratosphere can be attributed to the enhanced air masses originated from the PBL over the terrestrial regions,where large amounts of pollutant emissions occur.The results imply that the influence of the DTST on the chemical composition and the climate of the stratosphere over the AM region is expected to become increasingly important,and is thereby of relevance to climate projection in an evolving climate.