The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations,being 2.5°C higher than the 1961−90 mean and with more than 900 stations reaching the record spring mean te...The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations,being 2.5°C higher than the 1961−90 mean and with more than 900 stations reaching the record spring mean temperature.This event exerted serious impacts in the region on agriculture,plant phenology,electricity transmission systems,and human health.In this paper,the contributions of human-induced climate change and anomalous anticyclonic circulation to this event are investigated using the newly homogenized observations and updated Met Office Hadley Centre system for attribution of extreme events,as well as CanESM2(Second Generation Canadian Earth System Model)simulations.Results indicate that both anthropogenic influences and anomalous anticyclonic circulation played significant roles in increasing the probability of the 2018 hottest spring.Quantitative estimates of the probability ratio show that anthropogenic forcing may have increased the chance of this event by ten-fold,while the anomalous circulation increased it by approximately two-fold.The persistent anomalous anticyclonic circulation located on the north side of China blocked the air with lower temperature from high latitudes into eastern China.Without anthropogenic forcing or without the anomalous circulation in northern China,the occurrence probability of the extreme warm spring is significantly reduced.展开更多
Purpose: The chemokine receptors CCR7 and CXCR4 have been shown to play an important role in cancer invasion and metastasis. This study was aimed to investigate CCR7 and CXCR4 expressions and evaluate the association ...Purpose: The chemokine receptors CCR7 and CXCR4 have been shown to play an important role in cancer invasion and metastasis. This study was aimed to investigate CCR7 and CXCR4 expressions and evaluate the association between their expressions and the clinicopathological features in gastrointestinal cancer. Method: 27 paired tissue samples from patients who had curative surgery for gastrointestinal cancer were obtained. Quantitative real-time PCR, immunochemistry assay and western blot analysis were carried out to investigate the expressions of CCR7, CXCR4 expressions in gastrointestinal cancer. Results: The cancer tissues expressed significant higher level of CCR7 (P = 0.000) and CXCR4 (P = 0.000) protein than the adjacent normal mucosa. Expressions of CCR7 (P = 0.002) and CXCR4 (P = 0.003) protein in cancer tissues exhibited significant correlation with differentiation in gastrointestinal cancer. Conclusion: Expressions of CCR7 and CXCR4 protein were associated with differentiation in gastrointestinal cancer. CCR7 and CXCR4 may be predictive factors for poor prognosis in patients with gastrointestinal cancer.展开更多
Using the NCEP-2 reanalysis data in 1979-2015, we analyze variations in the coupled stratosphere-troposphere system and attribute them to the polar vortex oscillation(PVO) and the 11-yr sunspot cycle(SC). Subsequently...Using the NCEP-2 reanalysis data in 1979-2015, we analyze variations in the coupled stratosphere-troposphere system and attribute them to the polar vortex oscillation(PVO) and the 11-yr sunspot cycle(SC). Subsequently, influences of PVO and SC on the near-ground temperature and extreme temperatures are diagnosed based on observations at 2419 surface stations in China over the same period. Empirical Orthogonal Function(EOF) analysis of geopotential height(GH) anomalies indicates that the first and second EOF modes together can explain nearly 50% of the total variance and they have different driving sources, active periods, and regions. The first EOF mode mainly represents variation characteristics of the polar vortex, and its active periods appear in late winter. It is found that a weakened polar vortex(larger amplitude in the positive time series of the first mode) corresponds to lower daily mean, minimum, and maximum temperatures and more frequent cold nights and days. This cooling effect mainly occur in northeastern China. The second EOF mode is closely related to the SC, and its major active periods are late autumn and early winter. The results reveal that strong solar activity(larger amplitude in the positive time series of the second mode) leads to cooling effects in northern China through accelerating seasonal transformation of the stratospheric circulation and enhancing intensity of the subtropical westerly jet in the upper troposphere and lower stratosphere. The near-ground temperature is lower than usual, especially for daily mean and minimum temperatures. The number of warm nights and days is significantly reduced, and cold nights and days become more frequent. Therefore,the first and second EOF mode time series of GH anomalies can be used as indices of PVO and solar activity, respectively; and can provide indications of winter cooling processes in China.展开更多
Daily precipitation data from 149 rain gauge stations in China and NCEP-NCAR reanalysis data during 1961-2018are used to investigate the interdecadal variability of summer precipitation in Northwest China and related ...Daily precipitation data from 149 rain gauge stations in China and NCEP-NCAR reanalysis data during 1961-2018are used to investigate the interdecadal variability of summer precipitation in Northwest China and related causes.The results suggest that,on the interdecadal timescale,Northwest China shifts into a rainy period from the year 1987,with an increase in the precipitation amount and intensity;an increase in the probability of moderate rain,heavy rain,torrential rain,and extremely heavy rain;and a decrease in the probability of light rain.More than 60%of the increase in precipitation can be attributed to rainfall with intensity above the grade of heavy rain.The associated interdecadal variability of atmospheric circulations over midlatitude Eurasia in summer is examined and it is found that the interdecadal variability is mainly characterized by the Silk Road pattern(SRP),with a cyclonic circulation anomaly and an anticyclonic circulation anomaly over central Asia and Mongolia,respectively;enhanced ascending motion and atmospheric instability in Northwest China;and strengthened easterly winds caused by the Mongolian anticyclonic anomaly along the northern boundary of the Tibetan Plateau.On the south side of the Mongolian anticyclone,the water vapor transported from the Pacific and Indian Oceans as well as the South China Sea to Northwest China by easterly winds increases significantly,providing the main water vapor source for the increase in precipitation in Northwest China on the interdecadal timescale.The transition of the Atlantic multidecadal oscillation to a positive phase may be the main cause of the interdecadal transition of the SRP to a positive phase,resulting in the interdecadal increase in summer precipitation in Northwest China.展开更多
Understanding and controlling defect in two-dimensional materials is important for both linear and nonlinear optoelectronic devices,especially in terms of tuning nonlinear optical absorption.Taking advantage of an ato...Understanding and controlling defect in two-dimensional materials is important for both linear and nonlinear optoelectronic devices,especially in terms of tuning nonlinear optical absorption.Taking advantage of an atomic defect formed easily by smaller size,molybdenum disulfide nanosheet is prepared successfully with a different size by gradient centrifugation.Interestingly,size-dependent sulfur vacancies are observed by high-resolution X-ray photoelectron spectroscopy,atomic force microscopy,and transmission electron microscopy.The defect effect on nonlinear absorption is investigated by Z-scan measurement at the wavelength of 800 nm.The results suggest the transition from saturable absorption to reverse saturable absorption can be observed in both dispersions and films.First principle calculations suggest that sulfur vacancies act as the trap state to capture the excited electrons.Moreover,an energy-level model with the trap state is put forward to explain the role of the sulfur vacancy defect in nonlinear optical absorption.The results suggest that saturable absorption and reverse saturable absorption originate from the competition between the excited,defect state and ground state absorption.Our finding provides a way to tune the nonlinear optical performance of optoelectronic devices by defect engineering.展开更多
基金the National Key Research and Development Program of China(Grant No.2018YFC1507702)the National Natural Science Foundation of China(Grant No.41775082)+3 种基金Y.SUN was supported by the National Key Research and Development Program of China(Grant No.2016YFA0600701)the National Natural Science Foundation of China(Grant No.41790471)N.CHRISTIDIS and P.A.STOTT were supported by the Met Office Hadley Centre Climate Programme funded by BEIS,Defrathe UK−China Research and Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fund,China.
文摘The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations,being 2.5°C higher than the 1961−90 mean and with more than 900 stations reaching the record spring mean temperature.This event exerted serious impacts in the region on agriculture,plant phenology,electricity transmission systems,and human health.In this paper,the contributions of human-induced climate change and anomalous anticyclonic circulation to this event are investigated using the newly homogenized observations and updated Met Office Hadley Centre system for attribution of extreme events,as well as CanESM2(Second Generation Canadian Earth System Model)simulations.Results indicate that both anthropogenic influences and anomalous anticyclonic circulation played significant roles in increasing the probability of the 2018 hottest spring.Quantitative estimates of the probability ratio show that anthropogenic forcing may have increased the chance of this event by ten-fold,while the anomalous circulation increased it by approximately two-fold.The persistent anomalous anticyclonic circulation located on the north side of China blocked the air with lower temperature from high latitudes into eastern China.Without anthropogenic forcing or without the anomalous circulation in northern China,the occurrence probability of the extreme warm spring is significantly reduced.
文摘Purpose: The chemokine receptors CCR7 and CXCR4 have been shown to play an important role in cancer invasion and metastasis. This study was aimed to investigate CCR7 and CXCR4 expressions and evaluate the association between their expressions and the clinicopathological features in gastrointestinal cancer. Method: 27 paired tissue samples from patients who had curative surgery for gastrointestinal cancer were obtained. Quantitative real-time PCR, immunochemistry assay and western blot analysis were carried out to investigate the expressions of CCR7, CXCR4 expressions in gastrointestinal cancer. Results: The cancer tissues expressed significant higher level of CCR7 (P = 0.000) and CXCR4 (P = 0.000) protein than the adjacent normal mucosa. Expressions of CCR7 (P = 0.002) and CXCR4 (P = 0.003) protein in cancer tissues exhibited significant correlation with differentiation in gastrointestinal cancer. Conclusion: Expressions of CCR7 and CXCR4 protein were associated with differentiation in gastrointestinal cancer. CCR7 and CXCR4 may be predictive factors for poor prognosis in patients with gastrointestinal cancer.
基金Supported by the National Key Research and Development Program of China(2016YFA0600701)National Natural Science Foundation of China(41775082 and 41675069)
文摘Using the NCEP-2 reanalysis data in 1979-2015, we analyze variations in the coupled stratosphere-troposphere system and attribute them to the polar vortex oscillation(PVO) and the 11-yr sunspot cycle(SC). Subsequently, influences of PVO and SC on the near-ground temperature and extreme temperatures are diagnosed based on observations at 2419 surface stations in China over the same period. Empirical Orthogonal Function(EOF) analysis of geopotential height(GH) anomalies indicates that the first and second EOF modes together can explain nearly 50% of the total variance and they have different driving sources, active periods, and regions. The first EOF mode mainly represents variation characteristics of the polar vortex, and its active periods appear in late winter. It is found that a weakened polar vortex(larger amplitude in the positive time series of the first mode) corresponds to lower daily mean, minimum, and maximum temperatures and more frequent cold nights and days. This cooling effect mainly occur in northeastern China. The second EOF mode is closely related to the SC, and its major active periods are late autumn and early winter. The results reveal that strong solar activity(larger amplitude in the positive time series of the second mode) leads to cooling effects in northern China through accelerating seasonal transformation of the stratospheric circulation and enhancing intensity of the subtropical westerly jet in the upper troposphere and lower stratosphere. The near-ground temperature is lower than usual, especially for daily mean and minimum temperatures. The number of warm nights and days is significantly reduced, and cold nights and days become more frequent. Therefore,the first and second EOF mode time series of GH anomalies can be used as indices of PVO and solar activity, respectively; and can provide indications of winter cooling processes in China.
基金Supported by the National Key Research and Development Program of China (2017YFA0605004)National Natural Science Foundation of China (41775082 and 41975100)。
文摘Daily precipitation data from 149 rain gauge stations in China and NCEP-NCAR reanalysis data during 1961-2018are used to investigate the interdecadal variability of summer precipitation in Northwest China and related causes.The results suggest that,on the interdecadal timescale,Northwest China shifts into a rainy period from the year 1987,with an increase in the precipitation amount and intensity;an increase in the probability of moderate rain,heavy rain,torrential rain,and extremely heavy rain;and a decrease in the probability of light rain.More than 60%of the increase in precipitation can be attributed to rainfall with intensity above the grade of heavy rain.The associated interdecadal variability of atmospheric circulations over midlatitude Eurasia in summer is examined and it is found that the interdecadal variability is mainly characterized by the Silk Road pattern(SRP),with a cyclonic circulation anomaly and an anticyclonic circulation anomaly over central Asia and Mongolia,respectively;enhanced ascending motion and atmospheric instability in Northwest China;and strengthened easterly winds caused by the Mongolian anticyclonic anomaly along the northern boundary of the Tibetan Plateau.On the south side of the Mongolian anticyclone,the water vapor transported from the Pacific and Indian Oceans as well as the South China Sea to Northwest China by easterly winds increases significantly,providing the main water vapor source for the increase in precipitation in Northwest China on the interdecadal timescale.The transition of the Atlantic multidecadal oscillation to a positive phase may be the main cause of the interdecadal transition of the SRP to a positive phase,resulting in the interdecadal increase in summer precipitation in Northwest China.
基金National Natural Science Foundation of China(11774288,11974279)Natural Science Foundation of Shaanxi Province(2019JC-25,2019-JM131,2019JM-236)。
文摘Understanding and controlling defect in two-dimensional materials is important for both linear and nonlinear optoelectronic devices,especially in terms of tuning nonlinear optical absorption.Taking advantage of an atomic defect formed easily by smaller size,molybdenum disulfide nanosheet is prepared successfully with a different size by gradient centrifugation.Interestingly,size-dependent sulfur vacancies are observed by high-resolution X-ray photoelectron spectroscopy,atomic force microscopy,and transmission electron microscopy.The defect effect on nonlinear absorption is investigated by Z-scan measurement at the wavelength of 800 nm.The results suggest the transition from saturable absorption to reverse saturable absorption can be observed in both dispersions and films.First principle calculations suggest that sulfur vacancies act as the trap state to capture the excited electrons.Moreover,an energy-level model with the trap state is put forward to explain the role of the sulfur vacancy defect in nonlinear optical absorption.The results suggest that saturable absorption and reverse saturable absorption originate from the competition between the excited,defect state and ground state absorption.Our finding provides a way to tune the nonlinear optical performance of optoelectronic devices by defect engineering.
基金supported by the National Natural Science Foundation of China(12074311,11774288,11974279)the Natural Science Foundation of Shaanxi Province(2019JC-25)。
