This study aimed to analyze the relationship between nutrient elements K, Ca, Mg, Cu, Mn, Zn and Fe in tobacco-planting soils and tobacco leaves from six main tobacco-producing areas, and to investigate the influences...This study aimed to analyze the relationship between nutrient elements K, Ca, Mg, Cu, Mn, Zn and Fe in tobacco-planting soils and tobacco leaves from six main tobacco-producing areas, and to investigate the influences of these elements on chemical composition and aroma components in tobacco leaves. Results showed that there were certain relationship between contents of nutrient elements in tobacco-planting soils and contents of corresponding elements in tobacco leaves; various elements exhibited different influences on the aroma quality of flue-cured tobacco. Based on the actual situation of nutrient contents in soils from different tobaccoproducing areas, contents of various elements in tobacco leaves should be regulated by soil fertilization and foliar spraying, thereby improving the aroma quality of flue-cured tobacco.展开更多
Based on the idea of risk evaluation, the existing lightning damage risk assessment methods are reviewed and summarized in this paper. And the power grid lightning damage risk assessment system is established on the b...Based on the idea of risk evaluation, the existing lightning damage risk assessment methods are reviewed and summarized in this paper. And the power grid lightning damage risk assessment system is established on the basis of lightning flashover risk evaluation methodology for transmission lines, and adopts the improved Analytic Hierarchy Process as the core algorithm. It can comprehensively evaluate the risk for transmission lines of regional grid, various sections of a line and each tower of the section, considering much more impact factors, including the running time of line, importance of grades, equipment damage, and the success rate of lightning stroke reclosing and so on. According to the calculation results of the risk assessment of the analytic hierarchy process and lightning flashover risk evaluation, the principles and methods of grade classification for power grid lightning damage risk map are studied, and give typical examples in the paper. It can describe the lightning withstanding ability much more scientifically and provide important references for the manage department of power system.展开更多
Species richness and abundance are two important species diversity variables that have attracted particular attention because of their significance in determining present and future species composition conditions. Thi...Species richness and abundance are two important species diversity variables that have attracted particular attention because of their significance in determining present and future species composition conditions. This paper aims to explain the qualitative and quantitative relationships between species diversity pattern and grain size (i.e. size of the sampling unit), and species diversity pattern and sampling area, and to analyze species diversity variability on active sand dunes in the Horqin Sandy Land, northeastern Inner Mongolia, China. A 50 mx50 m sampling plot was selected on the windward slope, where the dominant species was annual herb Agriophyllum squarrosum. Species composition and abundance at five grain sizes were recorded, and the species-area curves were produced for thirteen grain sizes. The range of values for species abundance tended to increase with in- creasing grain size in the study area, whereas, generally, species richness did not follow this rule because of poor species richness on the windward slope of active sand dunes. However, the homogeneity of species richness in- creased significantly. With the increase in sampling area, species abundance increased linearly, but richness in- creased logarithmically. Furthermore, variograms showed that species diversity on the windward slope of active sand dunes was weakly anisotropic and the distribution pattern was random, according to the Moran Coefficient. The results also showed that species richness was low, with a random distribution pattern. This conflicts with the results of previous studies that showed spatial aggregation in lower richness in a sampling area within a community and inferred that the physical processes play a more important role in species diversity than distribution pattern on active sand dunes. Further research into different diversity patterns and mechanisms between active sand dunes and interdune lowlands should be conducted to better understand biodiversity conservation in sand dune fields.展开更多
Objective:The aim of this study was to investigate the sensitivity of chemotherapeutic agents 5-FU,cisplatin(DDP) or TAXOL on colon cancer cell line SW480 with different methods,to find out the best examine time perio...Objective:The aim of this study was to investigate the sensitivity of chemotherapeutic agents 5-FU,cisplatin(DDP) or TAXOL on colon cancer cell line SW480 with different methods,to find out the best examine time period for further study of chemotherapeutic sensitivities.Methods:The SW480 cell was treated with 5-FU(200μg/mL),DDP(150μg/mL) or TAXOL(50μg/mL) respectively for 4h,8h or 12h.MTT assay was used to examine the cell survival rate,Annexin V/PI assay was used to analysis the apoptosis rate,Western Blot assay was applied to examine the expression of apoptotic protein.Results:(1) Results of MTT assay showed that the survival rate of SW480 cells at 4h,8h or 12h was:5-FU(200μg/mL)96.0%±8.2%,85.4%±7.8%,74.4% ±10.2%(P<0.05);DDP(150μg/mL) 99.0%±6.4%,88.7%±4.7%(P<0.05),46.9%±2.6%(P<0.01);TAXOL(50μg/mL) 51.5%±4.2%(P<0.01),31.9%±3.1%,17.6%±2.3%,or blank group 97.2%±5.8%,98.7%±7.2%,97.5%±7.5% respectively.(2) The apoptosis rate of cancer cells at 4h,8h or 12h was:control group:3.4%±0.2%,6.2%±0.4%,7.0%±0.5%;5-FU(200μg/mL) 4.0%±0.3%,4.8%±0.4%,7.7%±0.7%;DDP(150μg/mL) 8.5%±0.9%,18.6%±1.6%(P<0.05),67.0%±6.2%(P<0.01);or TAXOL(50μg/mL) 32.0%±5.2%(P<0.01),76.6%±8.5%,94.0% ±8.2%,respectively.(3) Western Blot assay showed that the expression of apoptosis associated protein.PARP,X-linked inhibitor of apoptasis(XIAP),Caspase-9 and Bcl-xL were changed.Conclusion:The sensitivity of chemotherapy could be assessed by MTT assay,Annexin V/PI assay and Western Blot.The best examine time of the three chemotherapuc agents was 5-FU(200μg/mL):>12h,DDP(150μg/mL):8-12h,or TAXOL(50μg/mL):<4h.展开更多
Objective The aim of the study was to investigate whether colon cancer stem cells induced by epidermal growth factor(EGF) to enter the cell cycle enhanced the chemosensitivity of colon cancer.Methods In vitro,EGF was ...Objective The aim of the study was to investigate whether colon cancer stem cells induced by epidermal growth factor(EGF) to enter the cell cycle enhanced the chemosensitivity of colon cancer.Methods In vitro,EGF was used to stimulate the entry of human colon cancer HCT116 cells into the cell cycle.Before and after treatment with EGF,CD133+ HCT116 cells were collected and flow cytometry was conducted to determine the apoptosis rate based on the 5-Fu and Ki-67 expression rates.The cell cycle distribution of the two groups was also determined.In vivo,a subcutaneous xenograft model of HCT116 human colon cancer cell lines in nude mice was established.The nude mice were divided into two groups and treated with EGF and 5-Fu,respectively.Differences in the growth of implanted tumors revealed the efficiency of cycle-induction combined chemotherapy.Results(1) After EGF stimulation,the S-G2/M proportion of CD133+ HCT116 cells and Ki67 expression were increased,indicating that more cancer stem cells entered the cell cycle and promoted proliferation;(2) After EGF stimulation,CD133+ HCT116 cells showed a higher apoptosis rate induced by 5-Fu.(3) Animal experiments showed that the group subjected to combined treatment with EGF and 5-Fu had smaller tumor sizes compared to the group treated with 5-Fu alone.Conclusion EGF enhanced tumor sensitivity to chemotherapeutic drugs,likely by promoting tumor stem cells to enter the cell cycle.展开更多
The characteristics of boundary layer structure during a persistent regional haze event over the central Liaoning city cluster of Northeast China from 16 to 21 December 2016 were investigated based on the measurements...The characteristics of boundary layer structure during a persistent regional haze event over the central Liaoning city cluster of Northeast China from 16 to 21 December 2016 were investigated based on the measurements of particulate matter(PM) concentration and the meteorological data within the atmospheric boundary layer(ABL). During the observational period, the maximum hourly mean PM_(2.5) and PM10 concentrations in Shenyang, Anshan, Fushun, and Benxi ranged from 276 to 355 μg m–3 and from 378 to 442 μg m–3, respectively, and the lowest hourly mean atmospheric visibility(VIS) in different cities ranged from 0.14 to 0.64 km. The central Liaoning city cluster was located in the front of a slowly moving high pressure and was mainly controlled by southerly winds. Wind speed(WS) within the ABL(〈 2 km) decreased significantly and WS at 10-m height mostly remained below 2 m s–1 during the hazy episodes, which was favorable for the accumulation of air pollutants. A potential temperature inversion layer existed throughout the entire ABL during the earlier hazy episode [from 0500 Local Time(LT) 18 December to 1100 LT 19 December], and then a potential temperature inversion layer developed with the bottom gradually decreased from 900 m to 300 m. Such a stable atmospheric stratification further weakened pollutant dispersion. The atmospheric boundary layer height(ABLH) estimated based on potential temperature profiles was mostly lower than 400 m and varied oppositely with PM_(2.5) in Shenyang. In summary, weak winds due to calm synoptic conditions, strong thermal inversion layer, and shallow atmospheric boundary layer contributed to the formation and development of this haze event.The backward trajectory analysis revealed the sources of air masses and explained the different characteristics of the haze episodes in the four cities.展开更多
This study analyzes and compares aerosol properties and meteorological conditions during two air pollution episodes in 19–22(E1) and 25–26(E2) December 2016 in Northeast China. The visibility, particulate matter...This study analyzes and compares aerosol properties and meteorological conditions during two air pollution episodes in 19–22(E1) and 25–26(E2) December 2016 in Northeast China. The visibility, particulate matter(PM) mass concentration, and surface meteorological observations were examined, together with the planetary boundary layer(PBL) properties and vertical profiles of aerosol extinction coefficient and volume depolarization ratio that were measured by a ground-based lidar in Shenyang of Liaoning Province, China during December 2016–January 2017.Results suggest that the low PBL height led to poor pollution dilution in E1, while the high PBL accompanied by low visibility in E2 might have been due to cross-regional and vertical air transmission. The PM mass concentration decreased as the PBL height increased in E1 while these two variables were positively correlated in E2. The enhanced winds in E2 diffused the pollutants and contributed largely to the aerosol transport. Strong temperature inversion in E1 resulted in increased PM2.5 and PM10 concentrations, and the winds in E2 favoured the southwesterly transport of aerosols from the North China Plain into the region surrounding Shenyang. The large extinction coefficient was partially attributed to the local pollution under the low PBL with high ground-surface PM mass concentrations in E1,whereas the cross-regional transport of aerosols within a high PBL and the low PM mass concentration near the ground in E2 were associated with severe aerosol extinction at high altitudes. These results may facilitate better understanding of the vertical distribution of aerosol properties during winter pollution events in Northeast China.展开更多
Visibility observed at different altitudes is favorable to understand the causes of air pol-lution.We conducted 4-years of observations of visibility at 2.8 and 60 m and particulate matter(PM)concentrations from 2015 ...Visibility observed at different altitudes is favorable to understand the causes of air pol-lution.We conducted 4-years of observations of visibility at 2.8 and 60 m and particulate matter(PM)concentrations from 2015 to 2018 in Shenyang,a provincial city in Northeast China.The results indicated that visibility increased with the increasing height in winter(especially at night),and decreased with height in summer(especially at the daytime).PM concentration exhibited opposite vertical variation to visibility,reflecting that visibility de-grades with the increase of aerosol concentration in the air.The radiosonde meteorological data showed that weak turbulence in the planetary boundary layer(PBL)in winter favored aerosols'accumulation near the surface.Whereas in summer,unstable atmospheric con-ditions,upper-level moister environment,and regional transport of air pollutants resulted in the deterioration of upper-level visibility.Inter-annual variation in the two-level visibility indicated that the upper-level visibility improved more significantly than low-level visibil-ity,much likely due to the reduction in emission of elevated point sources in Shenyang.Our study suggested that strengthening the control of surface non-point emissions is a promis-ing control strategy to improve Shenyang air quality.展开更多
Sunshine duration(SD) is adopted widely to study global dimming/brightening. However, long-term simultaneous measurements of SD and closely related impact factors require further analysis to elucidate how and why SD h...Sunshine duration(SD) is adopted widely to study global dimming/brightening. However, long-term simultaneous measurements of SD and closely related impact factors require further analysis to elucidate how and why SD has varied during the past decades. In this study, a long-term(1958–2021) SD data series obtained from the Shangdianzi Global Atmosphere Watch(GAW) station in China was analyzed to detect linear trends, climatic jumps, and climatic periods in SD using linear fitting, the Mann–Kendall trend test, and the continuous wavelet transform method. Annual SD exhibited steady dimming(-67.3 h decade-1) before 2010, followed by a period of brightening(189.9 h decade-1)during 2011–2020. An abrupt jump in annual SD occurred in 1995, and the annual SD anomaly exhibited significant oscillation with ~3-yr periodicity during 1960–1978. Partial least squares analysis revealed that annual SD anomaly was associated with variations in relative humidity, gale days, cloud cover, and black carbon(BC). Further analysis of the clear-sky daily sunshine percentage(DSP) and simultaneous measurements of aerosol properties, including aerosol optical depth, aerosol extinction coefficient, single scattering albedo(SSA), BC, and total suspended particulates, suggested that variation in DSP was affected primarily by aerosol scattering and absorption. Furthermore, the hourly clear-sky SD at high aerosol loading was approximately 60% and 56% of that at middle and low aerosol loadings, respectively. The pattern of diurnal variation in clear-sky hourly SD, as well as the actual values, can be affected by the fine particulate concentration, aerosol extinction coefficient, and SSA.展开更多
The horizontal coordinate systems commonly used in most global ocean models are the spherical latitude-longit- ude grid and displaced poles, such as a tripolar grid. The effect of the horizontal coordinate system on A...The horizontal coordinate systems commonly used in most global ocean models are the spherical latitude-longit- ude grid and displaced poles, such as a tripolar grid. The effect of the horizontal coordinate system on Atlantic meri- dional overturning circulation (AMOC) is evaluated by using an OGCM (ocean general circulation model). Two ex- periments are conducted with the model---one using a latitude-longitude grid (referred to as Latl) and the other us- ing a tripolar grid (referred to as Tri). The results show that Tri simulates a stronger North Atlantic deep water (NADW) than Lat_l, as more saline water masses enter the Greenland-Iceland-Norwegian (GIN) seas in Tri. The stronger NADW can be attributed to two factors. One is the removal of the zonal filter in Tri, which leads to an in- creasing of the zonal gradient of temperature and salinity, thus strengthening the north geostrophic flow. In turn, it decreases the positive subsurface temperature and salinity biases in the subtropical regions. The other may be associ- ated with topography at the North Pole, because realistic topography is applied in the tripolar grid while the latitude-longitude grid employs an artificial island around the North Pole. In order to evaluate the effect of the filter on AMOC, three enhanced filter experiments are carried out. Compared to Lat_l, an enhanced filter can also aug- ment NADW formation, since more saline water is suppressed in the GIN seas, but accumulated in the Labrador Sea, especially in experiment Lat_2 S, which is the experiment with an enhanced filter on salinity.展开更多
Annual plants are the main vegetation in arid and semi-arid desert regions.Because of their unique traits,they are the optimal experimental subjects for eco-logical studies.In this article,we summarize annual plants’...Annual plants are the main vegetation in arid and semi-arid desert regions.Because of their unique traits,they are the optimal experimental subjects for eco-logical studies.In this article,we summarize annual plants’seed germination strategies,seedling adaptability mechanism to environments,seed dispersal,and soil seed banks.We also discuss the biotic and abiotic factors affecting the composition and dynamics of annual plant populations and communities.Because annual plants have important ecological functions in desert vegetation systems,this study on annual plants will be of great benefit to the conservation and restoration of desert ecosystems,the rational utilization of resources,and the sustainable development of desert regions.展开更多
We used parallel sunshine duration datasets obtained with a Jordan sunshine recorder and three automatic sunshine duration sensors to investigate the differences between these instruments.We used measurements obtained...We used parallel sunshine duration datasets obtained with a Jordan sunshine recorder and three automatic sunshine duration sensors to investigate the differences between these instruments.We used measurements obtained at Shangdianzi(SDZ)regional Global Atmosphere Watch(GAW)station with a Jordan sunshine recorder,a DFC2 photoelectric sunshine meter,a CHP1 pyrheliometer,and two CMP11 pyranometers from 1 January to 5 July 2019 and from 3 November 2020 to 28 February 2021.The results showed that the daily sunshine duration measurements obtained from the Jordan sunshine recorder were comparable with those from the DFC2 meter and the CMP11 pyranometers under all-sky conditions,but were considerably different from those observed by the CHP1 pyrheliometer.An analysis of potential influencing factors showed that the solar zenith angle,the spectral range of the automatic sensors,the relative humidity,and the sky conditions were the main factors affecting the measurements of sunshine duration between the Jordan sunshine recorder and three automatic sensors.We proposed a simple linear regression function-the DFC2-equivalent sunshine duration estimation(DFCESD)model—to guarantee the consistency of the long-term sunshine duration series observed by the Jordan sunshine recorder at SDZ and the measurements from the DFC2 meter.Validation of the DFCESD model showed that the mean absolute difference(MAD)between the daily sunshine duration observed by the Jordan sunshine recorder and those from the DFC2 meter improved from-0.7 to-0.2 h day^(-1),the relative deviation(RD)improved from-9.3%to-2.3%,and the root-mean-square deviation(RMSD)decreased from 1.0 to 0.8 h day^(-1).展开更多
In the present report,cyclin-dependent kinase1(CDK1)siRNA was transfected into cells to silence the CDK1 gene expression and study its role in the cell cycle and cell apoptosis.The siRNA targeting CDK1 gene was chemic...In the present report,cyclin-dependent kinase1(CDK1)siRNA was transfected into cells to silence the CDK1 gene expression and study its role in the cell cycle and cell apoptosis.The siRNA targeting CDK1 gene was chemically synthesized and transfected into Hela cells by lipofectamine 2000.The expression levels of CDK1 gene and protein were examined by real-time quantitative polymerase chain reaction(PCR)and Western blot,respectively.The cell cycle was analyzed by using DNA content analysis byflow cytometry.Cell apoptosis was detected by the Annexin V/PI method.The morphological changes of transfected cells were examined under the microscopy by Wright-Giemsa stain.CDK1 gene was successfully silenced by its siRNA,and the CDK1 protein expression level was decreased significantly,especially from 48th h to 60th h after transfection.The DNA content analysis showed that transfection of CDK1 siRNA led to cells accumulating in G2/M phase.There was no significant difference in the apoptotic rate between transfected cells and the control cells after transfection of CDK1 siRNA for 48 or 60 h.More double nucleus or multinucleus cells could be seen under the microscopy among the transfected cells.The decreased CDK1 expression by siRNA silencing gave rise to cell cycle arrest in G2/M phase but did not induce apoptosis.展开更多
文摘This study aimed to analyze the relationship between nutrient elements K, Ca, Mg, Cu, Mn, Zn and Fe in tobacco-planting soils and tobacco leaves from six main tobacco-producing areas, and to investigate the influences of these elements on chemical composition and aroma components in tobacco leaves. Results showed that there were certain relationship between contents of nutrient elements in tobacco-planting soils and contents of corresponding elements in tobacco leaves; various elements exhibited different influences on the aroma quality of flue-cured tobacco. Based on the actual situation of nutrient contents in soils from different tobaccoproducing areas, contents of various elements in tobacco leaves should be regulated by soil fertilization and foliar spraying, thereby improving the aroma quality of flue-cured tobacco.
文摘Based on the idea of risk evaluation, the existing lightning damage risk assessment methods are reviewed and summarized in this paper. And the power grid lightning damage risk assessment system is established on the basis of lightning flashover risk evaluation methodology for transmission lines, and adopts the improved Analytic Hierarchy Process as the core algorithm. It can comprehensively evaluate the risk for transmission lines of regional grid, various sections of a line and each tower of the section, considering much more impact factors, including the running time of line, importance of grades, equipment damage, and the success rate of lightning stroke reclosing and so on. According to the calculation results of the risk assessment of the analytic hierarchy process and lightning flashover risk evaluation, the principles and methods of grade classification for power grid lightning damage risk map are studied, and give typical examples in the paper. It can describe the lightning withstanding ability much more scientifically and provide important references for the manage department of power system.
基金funded by the National Natural Science Foundation of China (41071187)the State Forestry Administration Industry Special Project (201004023)
文摘Species richness and abundance are two important species diversity variables that have attracted particular attention because of their significance in determining present and future species composition conditions. This paper aims to explain the qualitative and quantitative relationships between species diversity pattern and grain size (i.e. size of the sampling unit), and species diversity pattern and sampling area, and to analyze species diversity variability on active sand dunes in the Horqin Sandy Land, northeastern Inner Mongolia, China. A 50 mx50 m sampling plot was selected on the windward slope, where the dominant species was annual herb Agriophyllum squarrosum. Species composition and abundance at five grain sizes were recorded, and the species-area curves were produced for thirteen grain sizes. The range of values for species abundance tended to increase with in- creasing grain size in the study area, whereas, generally, species richness did not follow this rule because of poor species richness on the windward slope of active sand dunes. However, the homogeneity of species richness in- creased significantly. With the increase in sampling area, species abundance increased linearly, but richness in- creased logarithmically. Furthermore, variograms showed that species diversity on the windward slope of active sand dunes was weakly anisotropic and the distribution pattern was random, according to the Moran Coefficient. The results also showed that species richness was low, with a random distribution pattern. This conflicts with the results of previous studies that showed spatial aggregation in lower richness in a sampling area within a community and inferred that the physical processes play a more important role in species diversity than distribution pattern on active sand dunes. Further research into different diversity patterns and mechanisms between active sand dunes and interdune lowlands should be conducted to better understand biodiversity conservation in sand dune fields.
基金Supported by grants of foundation of "973" Program (No. 2009CB521802)National Natural Science foundation of China (No. 30872472,30973496,30800569)Natural Science Foundation of HuBei Province (No. 2008CDB174,2009CDB239)
文摘Objective:The aim of this study was to investigate the sensitivity of chemotherapeutic agents 5-FU,cisplatin(DDP) or TAXOL on colon cancer cell line SW480 with different methods,to find out the best examine time period for further study of chemotherapeutic sensitivities.Methods:The SW480 cell was treated with 5-FU(200μg/mL),DDP(150μg/mL) or TAXOL(50μg/mL) respectively for 4h,8h or 12h.MTT assay was used to examine the cell survival rate,Annexin V/PI assay was used to analysis the apoptosis rate,Western Blot assay was applied to examine the expression of apoptotic protein.Results:(1) Results of MTT assay showed that the survival rate of SW480 cells at 4h,8h or 12h was:5-FU(200μg/mL)96.0%±8.2%,85.4%±7.8%,74.4% ±10.2%(P<0.05);DDP(150μg/mL) 99.0%±6.4%,88.7%±4.7%(P<0.05),46.9%±2.6%(P<0.01);TAXOL(50μg/mL) 51.5%±4.2%(P<0.01),31.9%±3.1%,17.6%±2.3%,or blank group 97.2%±5.8%,98.7%±7.2%,97.5%±7.5% respectively.(2) The apoptosis rate of cancer cells at 4h,8h or 12h was:control group:3.4%±0.2%,6.2%±0.4%,7.0%±0.5%;5-FU(200μg/mL) 4.0%±0.3%,4.8%±0.4%,7.7%±0.7%;DDP(150μg/mL) 8.5%±0.9%,18.6%±1.6%(P<0.05),67.0%±6.2%(P<0.01);or TAXOL(50μg/mL) 32.0%±5.2%(P<0.01),76.6%±8.5%,94.0% ±8.2%,respectively.(3) Western Blot assay showed that the expression of apoptosis associated protein.PARP,X-linked inhibitor of apoptasis(XIAP),Caspase-9 and Bcl-xL were changed.Conclusion:The sensitivity of chemotherapy could be assessed by MTT assay,Annexin V/PI assay and Western Blot.The best examine time of the three chemotherapuc agents was 5-FU(200μg/mL):>12h,DDP(150μg/mL):8-12h,or TAXOL(50μg/mL):<4h.
文摘Objective The aim of the study was to investigate whether colon cancer stem cells induced by epidermal growth factor(EGF) to enter the cell cycle enhanced the chemosensitivity of colon cancer.Methods In vitro,EGF was used to stimulate the entry of human colon cancer HCT116 cells into the cell cycle.Before and after treatment with EGF,CD133+ HCT116 cells were collected and flow cytometry was conducted to determine the apoptosis rate based on the 5-Fu and Ki-67 expression rates.The cell cycle distribution of the two groups was also determined.In vivo,a subcutaneous xenograft model of HCT116 human colon cancer cell lines in nude mice was established.The nude mice were divided into two groups and treated with EGF and 5-Fu,respectively.Differences in the growth of implanted tumors revealed the efficiency of cycle-induction combined chemotherapy.Results(1) After EGF stimulation,the S-G2/M proportion of CD133+ HCT116 cells and Ki67 expression were increased,indicating that more cancer stem cells entered the cell cycle and promoted proliferation;(2) After EGF stimulation,CD133+ HCT116 cells showed a higher apoptosis rate induced by 5-Fu.(3) Animal experiments showed that the group subjected to combined treatment with EGF and 5-Fu had smaller tumor sizes compared to the group treated with 5-Fu alone.Conclusion EGF enhanced tumor sensitivity to chemotherapeutic drugs,likely by promoting tumor stem cells to enter the cell cycle.
基金Supported by the National Key R&D Program of China(2016YFC0203304)Science and Technology Research Project(Doctoral Research Special Fund)of Liaoning Meteorological Office(D201603)+3 种基金National Natural Science Foundation of China(41375146 and41605081)China Meteorological Administration Special Public Welfare Research Fund(GYHY201406031)Basic Research Funds of Central Public Welfare Research Institutes(2016SYIAEZD3)China Meteorological Administration Special Funds for Core Business Development(CMAHX20160306)
文摘The characteristics of boundary layer structure during a persistent regional haze event over the central Liaoning city cluster of Northeast China from 16 to 21 December 2016 were investigated based on the measurements of particulate matter(PM) concentration and the meteorological data within the atmospheric boundary layer(ABL). During the observational period, the maximum hourly mean PM_(2.5) and PM10 concentrations in Shenyang, Anshan, Fushun, and Benxi ranged from 276 to 355 μg m–3 and from 378 to 442 μg m–3, respectively, and the lowest hourly mean atmospheric visibility(VIS) in different cities ranged from 0.14 to 0.64 km. The central Liaoning city cluster was located in the front of a slowly moving high pressure and was mainly controlled by southerly winds. Wind speed(WS) within the ABL(〈 2 km) decreased significantly and WS at 10-m height mostly remained below 2 m s–1 during the hazy episodes, which was favorable for the accumulation of air pollutants. A potential temperature inversion layer existed throughout the entire ABL during the earlier hazy episode [from 0500 Local Time(LT) 18 December to 1100 LT 19 December], and then a potential temperature inversion layer developed with the bottom gradually decreased from 900 m to 300 m. Such a stable atmospheric stratification further weakened pollutant dispersion. The atmospheric boundary layer height(ABLH) estimated based on potential temperature profiles was mostly lower than 400 m and varied oppositely with PM_(2.5) in Shenyang. In summary, weak winds due to calm synoptic conditions, strong thermal inversion layer, and shallow atmospheric boundary layer contributed to the formation and development of this haze event.The backward trajectory analysis revealed the sources of air masses and explained the different characteristics of the haze episodes in the four cities.
基金Supported by the National Key Research and Development Program of China(2016YFC0203304 and 2016YFA0601901)National Natural Science Foundation of China(41605112,41590874,41375153,and 41375146)+2 种基金Chinese Academy of Meteorological Sciences Basic Research Fund(2017Z011,2016Z001,and 2014R17)Climate Change Special Fund of China Meteorological Administration(CCSF201504)Special Project for Doctoral Research of Liaoning Provincial Meteorological Bureau(D201501)
文摘This study analyzes and compares aerosol properties and meteorological conditions during two air pollution episodes in 19–22(E1) and 25–26(E2) December 2016 in Northeast China. The visibility, particulate matter(PM) mass concentration, and surface meteorological observations were examined, together with the planetary boundary layer(PBL) properties and vertical profiles of aerosol extinction coefficient and volume depolarization ratio that were measured by a ground-based lidar in Shenyang of Liaoning Province, China during December 2016–January 2017.Results suggest that the low PBL height led to poor pollution dilution in E1, while the high PBL accompanied by low visibility in E2 might have been due to cross-regional and vertical air transmission. The PM mass concentration decreased as the PBL height increased in E1 while these two variables were positively correlated in E2. The enhanced winds in E2 diffused the pollutants and contributed largely to the aerosol transport. Strong temperature inversion in E1 resulted in increased PM2.5 and PM10 concentrations, and the winds in E2 favoured the southwesterly transport of aerosols from the North China Plain into the region surrounding Shenyang. The large extinction coefficient was partially attributed to the local pollution under the low PBL with high ground-surface PM mass concentrations in E1,whereas the cross-regional transport of aerosols within a high PBL and the low PM mass concentration near the ground in E2 were associated with severe aerosol extinction at high altitudes. These results may facilitate better understanding of the vertical distribution of aerosol properties during winter pollution events in Northeast China.
基金This work was supported by the National Natural Science Foundation of China(No.41730647)the Natural Science Foundation of Liaoning Province(No.2020-MS-350)+3 种基金the Science&Technology Project of Liaoning Province(No.2019JH8/10300095)the Key Program of Science Foundation of Liaoning Meteorological Office(Nos.201904,D202101)the Basic Research Funds of Central Public Welfare Research Institutes(Nos.2018SYIAEZD4,2020SYIAEZD1)the Open Project of Shangdianzi National Atmosphere Background Station(No.SDZ2020620)
文摘Visibility observed at different altitudes is favorable to understand the causes of air pol-lution.We conducted 4-years of observations of visibility at 2.8 and 60 m and particulate matter(PM)concentrations from 2015 to 2018 in Shenyang,a provincial city in Northeast China.The results indicated that visibility increased with the increasing height in winter(especially at night),and decreased with height in summer(especially at the daytime).PM concentration exhibited opposite vertical variation to visibility,reflecting that visibility de-grades with the increase of aerosol concentration in the air.The radiosonde meteorological data showed that weak turbulence in the planetary boundary layer(PBL)in winter favored aerosols'accumulation near the surface.Whereas in summer,unstable atmospheric con-ditions,upper-level moister environment,and regional transport of air pollutants resulted in the deterioration of upper-level visibility.Inter-annual variation in the two-level visibility indicated that the upper-level visibility improved more significantly than low-level visibil-ity,much likely due to the reduction in emission of elevated point sources in Shenyang.Our study suggested that strengthening the control of surface non-point emissions is a promis-ing control strategy to improve Shenyang air quality.
基金Supported by the China Scholarship Council (202205330024)National Key Research and Development Program of China (2017YFB0504002)+1 种基金National Science and Technology Infrastructure Platform Project (2017)Special Fund for Basic Scientific Research of Institute of Urban Meteorology (IUMKY201735)。
文摘Sunshine duration(SD) is adopted widely to study global dimming/brightening. However, long-term simultaneous measurements of SD and closely related impact factors require further analysis to elucidate how and why SD has varied during the past decades. In this study, a long-term(1958–2021) SD data series obtained from the Shangdianzi Global Atmosphere Watch(GAW) station in China was analyzed to detect linear trends, climatic jumps, and climatic periods in SD using linear fitting, the Mann–Kendall trend test, and the continuous wavelet transform method. Annual SD exhibited steady dimming(-67.3 h decade-1) before 2010, followed by a period of brightening(189.9 h decade-1)during 2011–2020. An abrupt jump in annual SD occurred in 1995, and the annual SD anomaly exhibited significant oscillation with ~3-yr periodicity during 1960–1978. Partial least squares analysis revealed that annual SD anomaly was associated with variations in relative humidity, gale days, cloud cover, and black carbon(BC). Further analysis of the clear-sky daily sunshine percentage(DSP) and simultaneous measurements of aerosol properties, including aerosol optical depth, aerosol extinction coefficient, single scattering albedo(SSA), BC, and total suspended particulates, suggested that variation in DSP was affected primarily by aerosol scattering and absorption. Furthermore, the hourly clear-sky SD at high aerosol loading was approximately 60% and 56% of that at middle and low aerosol loadings, respectively. The pattern of diurnal variation in clear-sky hourly SD, as well as the actual values, can be affected by the fine particulate concentration, aerosol extinction coefficient, and SSA.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2013CB956204)National Natural Science Foundation of China(41530426)
文摘The horizontal coordinate systems commonly used in most global ocean models are the spherical latitude-longit- ude grid and displaced poles, such as a tripolar grid. The effect of the horizontal coordinate system on Atlantic meri- dional overturning circulation (AMOC) is evaluated by using an OGCM (ocean general circulation model). Two ex- periments are conducted with the model---one using a latitude-longitude grid (referred to as Latl) and the other us- ing a tripolar grid (referred to as Tri). The results show that Tri simulates a stronger North Atlantic deep water (NADW) than Lat_l, as more saline water masses enter the Greenland-Iceland-Norwegian (GIN) seas in Tri. The stronger NADW can be attributed to two factors. One is the removal of the zonal filter in Tri, which leads to an in- creasing of the zonal gradient of temperature and salinity, thus strengthening the north geostrophic flow. In turn, it decreases the positive subsurface temperature and salinity biases in the subtropical regions. The other may be associ- ated with topography at the North Pole, because realistic topography is applied in the tripolar grid while the latitude-longitude grid employs an artificial island around the North Pole. In order to evaluate the effect of the filter on AMOC, three enhanced filter experiments are carried out. Compared to Lat_l, an enhanced filter can also aug- ment NADW formation, since more saline water is suppressed in the GIN seas, but accumulated in the Labrador Sea, especially in experiment Lat_2 S, which is the experiment with an enhanced filter on salinity.
基金The project was supported by the National Science and Technology Tackle of China(No.2005BA517A08)Desert Monitor Programme of State Forestry Administration,China(No.00-08-05).
文摘Annual plants are the main vegetation in arid and semi-arid desert regions.Because of their unique traits,they are the optimal experimental subjects for eco-logical studies.In this article,we summarize annual plants’seed germination strategies,seedling adaptability mechanism to environments,seed dispersal,and soil seed banks.We also discuss the biotic and abiotic factors affecting the composition and dynamics of annual plant populations and communities.Because annual plants have important ecological functions in desert vegetation systems,this study on annual plants will be of great benefit to the conservation and restoration of desert ecosystems,the rational utilization of resources,and the sustainable development of desert regions.
基金Supported by the National Key Research and Development Program of China(2017YFB0504002)Special Fund for Basic Scientific Research of Institute of Urban Meteorology(2017)。
文摘We used parallel sunshine duration datasets obtained with a Jordan sunshine recorder and three automatic sunshine duration sensors to investigate the differences between these instruments.We used measurements obtained at Shangdianzi(SDZ)regional Global Atmosphere Watch(GAW)station with a Jordan sunshine recorder,a DFC2 photoelectric sunshine meter,a CHP1 pyrheliometer,and two CMP11 pyranometers from 1 January to 5 July 2019 and from 3 November 2020 to 28 February 2021.The results showed that the daily sunshine duration measurements obtained from the Jordan sunshine recorder were comparable with those from the DFC2 meter and the CMP11 pyranometers under all-sky conditions,but were considerably different from those observed by the CHP1 pyrheliometer.An analysis of potential influencing factors showed that the solar zenith angle,the spectral range of the automatic sensors,the relative humidity,and the sky conditions were the main factors affecting the measurements of sunshine duration between the Jordan sunshine recorder and three automatic sensors.We proposed a simple linear regression function-the DFC2-equivalent sunshine duration estimation(DFCESD)model—to guarantee the consistency of the long-term sunshine duration series observed by the Jordan sunshine recorder at SDZ and the measurements from the DFC2 meter.Validation of the DFCESD model showed that the mean absolute difference(MAD)between the daily sunshine duration observed by the Jordan sunshine recorder and those from the DFC2 meter improved from-0.7 to-0.2 h day^(-1),the relative deviation(RD)improved from-9.3%to-2.3%,and the root-mean-square deviation(RMSD)decreased from 1.0 to 0.8 h day^(-1).
基金supported by grants from the National Basic Research Program of China(No.2004CB518705)the National Natural Science Foundation of China(No.30570908).
文摘In the present report,cyclin-dependent kinase1(CDK1)siRNA was transfected into cells to silence the CDK1 gene expression and study its role in the cell cycle and cell apoptosis.The siRNA targeting CDK1 gene was chemically synthesized and transfected into Hela cells by lipofectamine 2000.The expression levels of CDK1 gene and protein were examined by real-time quantitative polymerase chain reaction(PCR)and Western blot,respectively.The cell cycle was analyzed by using DNA content analysis byflow cytometry.Cell apoptosis was detected by the Annexin V/PI method.The morphological changes of transfected cells were examined under the microscopy by Wright-Giemsa stain.CDK1 gene was successfully silenced by its siRNA,and the CDK1 protein expression level was decreased significantly,especially from 48th h to 60th h after transfection.The DNA content analysis showed that transfection of CDK1 siRNA led to cells accumulating in G2/M phase.There was no significant difference in the apoptotic rate between transfected cells and the control cells after transfection of CDK1 siRNA for 48 or 60 h.More double nucleus or multinucleus cells could be seen under the microscopy among the transfected cells.The decreased CDK1 expression by siRNA silencing gave rise to cell cycle arrest in G2/M phase but did not induce apoptosis.