The crustal thicknesses and the Poisson’s ratios under the seismic stations can be calculated by receiver function method with H-κ stacking effectively. But the stacking results are affected to some extent by the av...The crustal thicknesses and the Poisson’s ratios under the seismic stations can be calculated by receiver function method with H-κ stacking effectively. But the stacking results are affected to some extent by the average crustal P-wave velocity. To eliminate this effect and get more accurate crustal structure along the Zhenkang-Luxi deep seismic sounding profile which lies in Yunnan Province, we calculate the receiver functions from the teleseismic events recorded by 11 temporary stations as well as 5 permanent ones along the profile and carry out the stacking with Vp obtained from the profile in this study. Our study shows that the crustal thicknesses along the Zhenkang-Luxi profile range from 34.8 km to 41.8 km with an average of 39 km. The crust is thicker in the middle part of the profile and thinner in both sides in general. Dramatic changes of crustal thickness about 3 km are detected across both the Lancangjiang fault and the Xiaojiang fault, which implies that these faults cut through the Moho. The lowest Poisson’s ratio under the stations is 0.22 and the highest is 0.27 with the mean of 0.25, which is lower than the global average value 0.27 in the continental crust. It suggests that most of the crust along the profile lacks mafic component, but contains more felsic substance. The low Poisson’s ratio also indicates that there is no satisfying condition for partial melting. We deduce that the material flow in the middle-lower crust in the southeastern margin of the Tibetan plateau may occur only in the north region of 24°N.展开更多
The catalytic oxidation effect of MnSO_(4)on As(Ⅲ) by air in an alkaline solution was investigated.According to the X-ray diffraction (XRD),scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and X-...The catalytic oxidation effect of MnSO_(4)on As(Ⅲ) by air in an alkaline solution was investigated.According to the X-ray diffraction (XRD),scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analysis results of the product,it was shown that the introduction of MnSO_(4)in the form of solution would generate Na_(0.55)Mn_(2)O_(4)·1.5H_(2)O with strong catalytic oxidation ability in the aerobic alkaline solution,whereas the catalytic effect of the other product MnOOH is not satisfactory.Under the optimal reaction conditions of temperature 90℃,As/Mn molar ratio 12.74:1,air flow rate1.0 L/min,and stirring speed 300 r/min,As(Ⅲ) can be completely oxidized after 2 hr reaction.The excellent catalytic oxidation ability of MnSO_(4)on As(Ⅲ) was mainly attributed to the indirect oxidation of As(Ⅲ) by the product Na_(0.55)Mn_(2)O_(4)·1.5H_(2)O.This study shows a convenient and efficient process for the oxidation of As(Ⅲ) in alkali solutions,which has potential application value for the pre-oxidation of arsenic-containing solution or the detoxification of As(Ⅲ).展开更多
SARS coronavirus （SARS-CoV） develops an antagonis- tic mechanism by which to evade the antiviral activities of interferon （IFN）. Previous studies suggested that SARS-CoV papain-like protease （PLpro） inhibits act...SARS coronavirus （SARS-CoV） develops an antagonis- tic mechanism by which to evade the antiviral activities of interferon （IFN）. Previous studies suggested that SARS-CoV papain-like protease （PLpro） inhibits activa- tion of the IRF3 pathway, which would normally elicit a robust IFN response, but the mechanism（s） used by SARS PLpro to inhibit activation of the IRF3 pathway is not fully known. In this study, we uncovered a novel mechanism that may explain how SARS PLpro effi- ciently inhibits activation of the IRF3 pathway. We found that expression of the membrane-anchored PLpro domain （PLpro-TM） from SARS-CoV inhibits STING/ TBKl/IKKE-mediated activation of type I IFNs and dis- rupts the phosphorylation and dimerization of IRF3, which are activated by STING and TBKI. Meanwhile, we showed that PLpro-TM physically interacts with TRAF3, TBK1, IKK~, STING, and IRF3, the key components that assemble the STING-TRAF3-TBK1 complex for activa- tion of IFN expression. However, the interaction between the components in STING-TRAF3-TBK1 complex is dis- rupted by PLpro-TM. Furthermore, SARS PLpro-TM reduces the levels of ubiquitinated forms of RIG-I, STING, TRAF3, TBK1, and IRF3 in the STING-TRAF3- TBK1 complex. These results collectively point to a new mechanism used by SARS-CoV through which PLpro negatively regulates IRF3 activation by interaction withSTING-TRAF3-TBK1 complex, yielding a SARS-CoV countermeasure against host innate immunity.展开更多
The transitional area between the northeastern margin of the Qinghai-Tibetan Plateau, Ordos Block and Alxa Block, also being the northern segment of the North-South Seismic Belt, is characterized by considerably high ...The transitional area between the northeastern margin of the Qinghai-Tibetan Plateau, Ordos Block and Alxa Block, also being the northern segment of the North-South Seismic Belt, is characterized by considerably high seismicity level and high risk of strong earthquakes. In view of the special tectonic environment and deep tectonic setting in this area, this study used two seismic wide-angle reflection/refraction cross profiles for double constraining, so as to more reliably obtain the fine-scale velocity structure characteristics in both the shallow and deep crust of individual blocks and their boundaries in the study area, and further discuss the seismogenic environment in seismic zones with strong historical earthquakes. In this paper, the P-wave data from the two profiles are processed and interpreted, and two-dimensional crustal velocity structure models along the two profiles are constructed by travel time forward modeling. The results show that there are great differences in velocity structure, shape of intra-crustal interfaces and crustal thickness among different blocks sampled by the two seismic profiles. The crustal thickness along the Lanzhou-Huianbu-Yulin seismic sounding profile （L1） increases from -43 km in the western margin of Ordos Block to -56 km in the Qilian Block to the west. In the Ordos Block, the velocity contours vary gently, and the average velocity of the crust is about 6.30 km s^-1; On the other hand, the velocity structures in the crust of the Qilian Block and the arc-like tectonic zone vary dramatically, and the average crustal velocities in these areas are about 0.10 km s^-1 lower than that of the Ordos Block. In addition, discontinuous low-velocity bodies （LVZ1 and LVZ2） are identified in the crust of the Qilian Block and the arc-like tectonic zone, the velocity of which is 0.10-0.20 krn s^-1 lower than that of the surroundings. The average crustal thickness of the Ordos Block is consistently estimated to be around 43 km along both Profile L2 （Tongchuan-Huianbu-Alashan left banner seismic sounding profile） and Profile L1. In contrast to the gently varying intra-crustal interfaces and velocity contours in the Ordos Block along Profile L 1, which is a typical structure characteristic of stable cratons, the crustal structure in the Ordos Block along Profile L2 exhibits rather complex variations. This indicates the presence of significant structural differences in the crust within the Ordos Block. The crustal structure of the Helan Mountain Qilian Block and the Yinchuan Basin is featured by ＂uplift and depression＂ undulations, showing the characteristics of localized compressional deformation. Moreover, there are low-velocity zones with altemative high and low velocities in the middle and lower crust beneath the Helan Mountain, where the velocity is about 0.15-0.25 km s^-1 lower than that of the surrounding areas. The crustal thickness of the Alxa Block is about 49 kin, and the velocity contours in the upper and middle-lower crust of the block vary significantly. The complex crustal velocity structure images along the two seismic sounding profiles L1 and L2 reveal considerable structural differences among different tectonic blocks, their coupling relationships and velocity structural features in the seismic zones where strong historical earthquakes occurred. The imaging result of this study provides fine-scale crustal structure information for further understanding the seismogenic environment and mechanism in the study area.展开更多
The 2019 novel coronavirus disease(COVID-19)pandemic has significantly impacted several aspects of the society and the economy.A problem that needs prompt attention in this situation is the increasing difficulties fac...The 2019 novel coronavirus disease(COVID-19)pandemic has significantly impacted several aspects of the society and the economy.A problem that needs prompt attention in this situation is the increasing difficulties faced by small-and mediumsized enterprises(SMEs)in raising capital,which has aroused great concern from multiple stakeholders such as public administrations and regulators.As the major supply of capital,financial service providers(FSPs)play a critical role in financing SMEs.However,how FSPs deal with SME financing during shocks has not yet been fully researched.Accordingly,in this study,a theoretical framework based on expectancy theory is proposed to explore the expected strategic adjustments of FSPs in financing SMEs.Specifically,this study investigates 272 FSPs in China on their expectancy and attitude on financing to SMEs during the COVID-19 pandemic.Furthermore,this study has divided FSPs into three categories:commercial banks,non-bank financial institutions,and credit-enhanced FSPs.Differences among these categories are compared and analyzed.展开更多
The photolysis frequency of NO2, j（NO2）, is an important analytical parameter in the study of tropospheric chemistry. A chemical actinometer （CA） was built to measure the ambient j（NQ） based on a high precision ...The photolysis frequency of NO2, j（NO2）, is an important analytical parameter in the study of tropospheric chemistry. A chemical actinometer （CA） was built to measure the ambient j（NQ） based on a high precision NOx instrument with 1 min time resolution. Parallel measurements of the ambient j（NO2） by using the CA and a commercial spectroradiometer （SR） were conducted at a typical urban site （Peking University Urban Environmental Monitoring Station） in Beijing. In general, good agreement was achieved between the CA and SR data with a high linear correlation coefficient （R2 = 0.977） and a regression slope of 1.12. The regression offset was negligible compared to the measured signal level. Thej（NO2） data were calculated using the tropospheric ultraviolet visible radiation （TUV） model, which was constrained to observe aerosol optical properties. The calculated j（NO2） was intermediate between the results obtained with CA and SR, demonstrating the consistency of all the parameters observed at this site. The good agreement between the CA and SR data, and the consistency with the TUV model results, demonstrate the good performance of the installed SR instrument. Since a drift of the SR sensitivity is expected by the manufacturer, we propose a regular check of the data acquired via SR against those obtained by CA for long-term delivery of a high quality series ofj（NO2） data. Establishing such a time series will be invaluable for analyzing the long-term atmospheric oxidation capacity trends as well as O3 pollution for urban Beijing.展开更多
Light-duty gasoline vehicles have drawn public attention in China due to their significant primary emissions of particulate matter and volatile organic compounds（VOCs）. However,little information on secondary aeroso...Light-duty gasoline vehicles have drawn public attention in China due to their significant primary emissions of particulate matter and volatile organic compounds（VOCs）. However,little information on secondary aerosol formation from exhaust for Chinese vehicles and fuel conditions is available. In this study, chamber experiments were conducted to quantify the potential of secondary aerosol formation from the exhaust of a port fuel injection gasoline engine. The engine and fuel used are common in the Chinese market, and the fuel satisfies the China V gasoline fuel standard. Substantial secondary aerosol formation was observed during a 4–5 hr simulation, which was estimated to represent more than 10 days of equivalent atmospheric photo-oxidation in Beijing. As a consequence, the extreme case secondary organic aerosol（SOA） production was 426 ± 85 mg/kg-fuel, with high levels of precursors and OH exposure. The low hygroscopicity of the aerosols formed inside the chamber suggests that SOA was the dominant chemical composition. Fourteen percent of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatile organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reductions of emissions of aerosol precursor gases from vehicles are essential to mediate pollution in China.展开更多
基金supported by the Seismic Youth Funding of Geophysical Exploration Center,China Earthquake Administration (YFGEC2016003)the National Natural Science Foundation of China (41774070 and 41404049)
文摘The crustal thicknesses and the Poisson’s ratios under the seismic stations can be calculated by receiver function method with H-κ stacking effectively. But the stacking results are affected to some extent by the average crustal P-wave velocity. To eliminate this effect and get more accurate crustal structure along the Zhenkang-Luxi deep seismic sounding profile which lies in Yunnan Province, we calculate the receiver functions from the teleseismic events recorded by 11 temporary stations as well as 5 permanent ones along the profile and carry out the stacking with Vp obtained from the profile in this study. Our study shows that the crustal thicknesses along the Zhenkang-Luxi profile range from 34.8 km to 41.8 km with an average of 39 km. The crust is thicker in the middle part of the profile and thinner in both sides in general. Dramatic changes of crustal thickness about 3 km are detected across both the Lancangjiang fault and the Xiaojiang fault, which implies that these faults cut through the Moho. The lowest Poisson’s ratio under the stations is 0.22 and the highest is 0.27 with the mean of 0.25, which is lower than the global average value 0.27 in the continental crust. It suggests that most of the crust along the profile lacks mafic component, but contains more felsic substance. The low Poisson’s ratio also indicates that there is no satisfying condition for partial melting. We deduce that the material flow in the middle-lower crust in the southeastern margin of the Tibetan plateau may occur only in the north region of 24°N.
基金supported by the National Key R&D Program of China (No.SQ2019YFC190179)National Natural Science Foundation of China (Nos.51864019 and 52004111)+2 种基金the Distinguished Professor Program of Jinggang Scholars in institutions of higher learning,Jiangxi Provincethe Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technologythe Jiangxi Province Natural Science Foundation of China (No.20181BAB206019)。
文摘The catalytic oxidation effect of MnSO_(4)on As(Ⅲ) by air in an alkaline solution was investigated.According to the X-ray diffraction (XRD),scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analysis results of the product,it was shown that the introduction of MnSO_(4)in the form of solution would generate Na_(0.55)Mn_(2)O_(4)·1.5H_(2)O with strong catalytic oxidation ability in the aerobic alkaline solution,whereas the catalytic effect of the other product MnOOH is not satisfactory.Under the optimal reaction conditions of temperature 90℃,As/Mn molar ratio 12.74:1,air flow rate1.0 L/min,and stirring speed 300 r/min,As(Ⅲ) can be completely oxidized after 2 hr reaction.The excellent catalytic oxidation ability of MnSO_(4)on As(Ⅲ) was mainly attributed to the indirect oxidation of As(Ⅲ) by the product Na_(0.55)Mn_(2)O_(4)·1.5H_(2)O.This study shows a convenient and efficient process for the oxidation of As(Ⅲ) in alkali solutions,which has potential application value for the pre-oxidation of arsenic-containing solution or the detoxification of As(Ⅲ).
文摘SARS coronavirus （SARS-CoV） develops an antagonis- tic mechanism by which to evade the antiviral activities of interferon （IFN）. Previous studies suggested that SARS-CoV papain-like protease （PLpro） inhibits activa- tion of the IRF3 pathway, which would normally elicit a robust IFN response, but the mechanism（s） used by SARS PLpro to inhibit activation of the IRF3 pathway is not fully known. In this study, we uncovered a novel mechanism that may explain how SARS PLpro effi- ciently inhibits activation of the IRF3 pathway. We found that expression of the membrane-anchored PLpro domain （PLpro-TM） from SARS-CoV inhibits STING/ TBKl/IKKE-mediated activation of type I IFNs and dis- rupts the phosphorylation and dimerization of IRF3, which are activated by STING and TBKI. Meanwhile, we showed that PLpro-TM physically interacts with TRAF3, TBK1, IKK~, STING, and IRF3, the key components that assemble the STING-TRAF3-TBK1 complex for activa- tion of IFN expression. However, the interaction between the components in STING-TRAF3-TBK1 complex is dis- rupted by PLpro-TM. Furthermore, SARS PLpro-TM reduces the levels of ubiquitinated forms of RIG-I, STING, TRAF3, TBK1, and IRF3 in the STING-TRAF3- TBK1 complex. These results collectively point to a new mechanism used by SARS-CoV through which PLpro negatively regulates IRF3 activation by interaction withSTING-TRAF3-TBK1 complex, yielding a SARS-CoV countermeasure against host innate immunity.
基金supported by the Special Projects of Scientific Research of the Earthquake Industry (Grant No. 201408023)the National Natural Science Foundation of China (Grant Nos. 41474076 & 41474077)
文摘The transitional area between the northeastern margin of the Qinghai-Tibetan Plateau, Ordos Block and Alxa Block, also being the northern segment of the North-South Seismic Belt, is characterized by considerably high seismicity level and high risk of strong earthquakes. In view of the special tectonic environment and deep tectonic setting in this area, this study used two seismic wide-angle reflection/refraction cross profiles for double constraining, so as to more reliably obtain the fine-scale velocity structure characteristics in both the shallow and deep crust of individual blocks and their boundaries in the study area, and further discuss the seismogenic environment in seismic zones with strong historical earthquakes. In this paper, the P-wave data from the two profiles are processed and interpreted, and two-dimensional crustal velocity structure models along the two profiles are constructed by travel time forward modeling. The results show that there are great differences in velocity structure, shape of intra-crustal interfaces and crustal thickness among different blocks sampled by the two seismic profiles. The crustal thickness along the Lanzhou-Huianbu-Yulin seismic sounding profile （L1） increases from -43 km in the western margin of Ordos Block to -56 km in the Qilian Block to the west. In the Ordos Block, the velocity contours vary gently, and the average velocity of the crust is about 6.30 km s^-1; On the other hand, the velocity structures in the crust of the Qilian Block and the arc-like tectonic zone vary dramatically, and the average crustal velocities in these areas are about 0.10 km s^-1 lower than that of the Ordos Block. In addition, discontinuous low-velocity bodies （LVZ1 and LVZ2） are identified in the crust of the Qilian Block and the arc-like tectonic zone, the velocity of which is 0.10-0.20 krn s^-1 lower than that of the surroundings. The average crustal thickness of the Ordos Block is consistently estimated to be around 43 km along both Profile L2 （Tongchuan-Huianbu-Alashan left banner seismic sounding profile） and Profile L1. In contrast to the gently varying intra-crustal interfaces and velocity contours in the Ordos Block along Profile L 1, which is a typical structure characteristic of stable cratons, the crustal structure in the Ordos Block along Profile L2 exhibits rather complex variations. This indicates the presence of significant structural differences in the crust within the Ordos Block. The crustal structure of the Helan Mountain Qilian Block and the Yinchuan Basin is featured by ＂uplift and depression＂ undulations, showing the characteristics of localized compressional deformation. Moreover, there are low-velocity zones with altemative high and low velocities in the middle and lower crust beneath the Helan Mountain, where the velocity is about 0.15-0.25 km s^-1 lower than that of the surrounding areas. The crustal thickness of the Alxa Block is about 49 kin, and the velocity contours in the upper and middle-lower crust of the block vary significantly. The complex crustal velocity structure images along the two seismic sounding profiles L1 and L2 reveal considerable structural differences among different tectonic blocks, their coupling relationships and velocity structural features in the seismic zones where strong historical earthquakes occurred. The imaging result of this study provides fine-scale crustal structure information for further understanding the seismogenic environment and mechanism in the study area.
基金supported by the National Natural Science Foundation of China(No.71872177).
文摘The 2019 novel coronavirus disease(COVID-19)pandemic has significantly impacted several aspects of the society and the economy.A problem that needs prompt attention in this situation is the increasing difficulties faced by small-and mediumsized enterprises(SMEs)in raising capital,which has aroused great concern from multiple stakeholders such as public administrations and regulators.As the major supply of capital,financial service providers(FSPs)play a critical role in financing SMEs.However,how FSPs deal with SME financing during shocks has not yet been fully researched.Accordingly,in this study,a theoretical framework based on expectancy theory is proposed to explore the expected strategic adjustments of FSPs in financing SMEs.Specifically,this study investigates 272 FSPs in China on their expectancy and attitude on financing to SMEs during the COVID-19 pandemic.Furthermore,this study has divided FSPs into three categories:commercial banks,non-bank financial institutions,and credit-enhanced FSPs.Differences among these categories are compared and analyzed.
基金Acknowledgements We have profited from discussions with Dr. Franz Rohrer. We acknowledge financial support from the National Natural Science Foundation of China （Grant Nos. 91544225 and 41375124）, the Strategic Priority Research Program of the Chinese Academy of Sciences （No. XDB05010500）, and the special fund of the State Key Joint Laboratory of Environment Simulation and Pollution Control （13Z02ESPCP）.
文摘The photolysis frequency of NO2, j（NO2）, is an important analytical parameter in the study of tropospheric chemistry. A chemical actinometer （CA） was built to measure the ambient j（NQ） based on a high precision NOx instrument with 1 min time resolution. Parallel measurements of the ambient j（NO2） by using the CA and a commercial spectroradiometer （SR） were conducted at a typical urban site （Peking University Urban Environmental Monitoring Station） in Beijing. In general, good agreement was achieved between the CA and SR data with a high linear correlation coefficient （R2 = 0.977） and a regression slope of 1.12. The regression offset was negligible compared to the measured signal level. Thej（NO2） data were calculated using the tropospheric ultraviolet visible radiation （TUV） model, which was constrained to observe aerosol optical properties. The calculated j（NO2） was intermediate between the results obtained with CA and SR, demonstrating the consistency of all the parameters observed at this site. The good agreement between the CA and SR data, and the consistency with the TUV model results, demonstrate the good performance of the installed SR instrument. Since a drift of the SR sensitivity is expected by the manufacturer, we propose a regular check of the data acquired via SR against those obtained by CA for long-term delivery of a high quality series ofj（NO2） data. Establishing such a time series will be invaluable for analyzing the long-term atmospheric oxidation capacity trends as well as O3 pollution for urban Beijing.
基金supported by the National Key Basic Research and Development Program (No. 2013CB228500)the National Basic Research Program (973) of China (Nos. 2013CB228503, 2013CB228502)+3 种基金National Natural Science Foundation of China (Nos. 91544214, 51636003)the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDB05010500)China Postdoctoral Science Foundation (No. 2015M580929)the State Key Lab of Automotive Safety and Energy at Tsinghua University for their support for the experiments
文摘Light-duty gasoline vehicles have drawn public attention in China due to their significant primary emissions of particulate matter and volatile organic compounds（VOCs）. However,little information on secondary aerosol formation from exhaust for Chinese vehicles and fuel conditions is available. In this study, chamber experiments were conducted to quantify the potential of secondary aerosol formation from the exhaust of a port fuel injection gasoline engine. The engine and fuel used are common in the Chinese market, and the fuel satisfies the China V gasoline fuel standard. Substantial secondary aerosol formation was observed during a 4–5 hr simulation, which was estimated to represent more than 10 days of equivalent atmospheric photo-oxidation in Beijing. As a consequence, the extreme case secondary organic aerosol（SOA） production was 426 ± 85 mg/kg-fuel, with high levels of precursors and OH exposure. The low hygroscopicity of the aerosols formed inside the chamber suggests that SOA was the dominant chemical composition. Fourteen percent of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatile organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reductions of emissions of aerosol precursor gases from vehicles are essential to mediate pollution in China.
