Mesozoic and Cenozoic magma activity in the Wolong Lake mining area of Huaibei is frequent,and the degree of magma intrusion into coal seams remarkable.On the one hand,magma intrusion affects the utilization of coal r...Mesozoic and Cenozoic magma activity in the Wolong Lake mining area of Huaibei is frequent,and the degree of magma intrusion into coal seams remarkable.On the one hand,magma intrusion affects the utilization of coal resources;on the other hand,the macro and trace elements in coal are redistributed to form new mineral types.This study uses the Wolong Lake magma intrusion coal seam as a research object.The mineral paragenesis for igneous rock,coke,and thermally-altered coal in an igneous intrusion zone is studied using SEM,XRD,and Raman spectroscopy.During igneous intrusion,the temperature and pressure of igneous rock metamorphose ambient low-rank coal to high-rank coal and coke.The response mechanism of minerals and trace elements to magmatic intrusion is discussed.The results are:①SEM analysis shows that ankerite and pyrite are formed from magma intrusion.Both minerals are strongly developed in the magma-coal contact zone,and less well developed in thermally-altered coal.②XRD analysis shows that igneous intrusion strongly influences the types and content of minerals in coke and thermally-altered coal.In addition to the increase amounts of ankerite and pyrite,chlorite,serpentine,and muscovite,and other secondary minerals,are generated following igneous intrusion.③Raman analysis suggests that thermally-altered coal possesses the characteristics of both pyrite and coke.Coke from the magma-coal boundary zone possesses the typical characteristics of pyrite.Igneous rock contains a mineral similar to pyrite,confirmed by both having similar Raman peaks.The scattering intensity of Ag indicates that the formation pressure of pyrite increases from thermally-altered coal via the boundary between the coke zone and the igneous rock.展开更多
Dear Editor,The COVID-19 pandemic still greatly threatens the public health worldwide and novel vaccines to highly effectively combat SARS-CoV-2 remains an unmet clinical need.However,redox imbalance in immune cells u...Dear Editor,The COVID-19 pandemic still greatly threatens the public health worldwide and novel vaccines to highly effectively combat SARS-CoV-2 remains an unmet clinical need.However,redox imbalance in immune cells under extra stimulation by vaccine or pathogens greatly dampens the quality of the induced immunity.1 In addition,people infected with COVID-19 that characterized by immune system malfunction were also approved to be attributed by the robust oxidative stress.展开更多
Upconversion （UC） and electrical properties of Na0.5Bi8.5-xErxTi7O27 （NBT-BIT-xEr, 0.00≤x≤0.25） ceramics were studied. Structural analysis revealed that a single inter-growth structured phase exists in all sampl...Upconversion （UC） and electrical properties of Na0.5Bi8.5-xErxTi7O27 （NBT-BIT-xEr, 0.00≤x≤0.25） ceramics were studied. Structural analysis revealed that a single inter-growth structured phase exists in all samples and the Er3＋ ion substituting for Bi3＋ at the A-site increases the orthorhombic distortion. Under the 980 nm laser excitation, two characteristic green emission bands and one red emission band were situated at 527, 548 and 670 nm, corresponding to the transitions 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2, respectively. The optimal photoluminescence （PL） were found in the NBT-BIT-0.20Er sample, and the emission color transforms from green to yellowish green. Temperature dependence of fluorescence intensity ratio （FIR） for NBT-BIT-0.20Er was measured ranging from 290 to 440 K and its maximum sensitivity was calculated to be about 0.0020 K-1 at 290 K. Dielectric measurements indicated that Tc slightly increased simultaneously with the decrease of tanS. Therefore, this ceramic has potential applications for high-temperature multifunctional devices.展开更多
The governance effects of directors’and officers’liability insurance(D&O insurance),an important tool for risk diversification,are of strong concern in the capital market.Using a sample of Chinese A-share listed...The governance effects of directors’and officers’liability insurance(D&O insurance),an important tool for risk diversification,are of strong concern in the capital market.Using a sample of Chinese A-share listed firms from2009 to 2018,we examine the impact of D&O insurance on excess corporate leverage.We find that D&O insurance is negatively associated with excess corporate leverage and that this result is consistent with a series of robustness tests.Further analyses show that D&O insurance impedes excess corporate leverage mainly because of its effect on external monitoring.The effect is more pronounced for firms that are state-owned,have political connections and are located in provinces with low marketization than for other firms.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.41373108 and 41702176)Natural Science Foundation of Anhui Province(No.1608085QD79)+1 种基金the Scientific and Technological Project of Huaibei Mining Industry(Group)Co.Ltd.(HK-2018-1)the Scientific and Technological Project of Anhui Traffic and Aviation Engineering(Group)Co.Ltd.We acknowledge the editors and reviewers for polishing the language and providing in-depth discussion.
文摘Mesozoic and Cenozoic magma activity in the Wolong Lake mining area of Huaibei is frequent,and the degree of magma intrusion into coal seams remarkable.On the one hand,magma intrusion affects the utilization of coal resources;on the other hand,the macro and trace elements in coal are redistributed to form new mineral types.This study uses the Wolong Lake magma intrusion coal seam as a research object.The mineral paragenesis for igneous rock,coke,and thermally-altered coal in an igneous intrusion zone is studied using SEM,XRD,and Raman spectroscopy.During igneous intrusion,the temperature and pressure of igneous rock metamorphose ambient low-rank coal to high-rank coal and coke.The response mechanism of minerals and trace elements to magmatic intrusion is discussed.The results are:①SEM analysis shows that ankerite and pyrite are formed from magma intrusion.Both minerals are strongly developed in the magma-coal contact zone,and less well developed in thermally-altered coal.②XRD analysis shows that igneous intrusion strongly influences the types and content of minerals in coke and thermally-altered coal.In addition to the increase amounts of ankerite and pyrite,chlorite,serpentine,and muscovite,and other secondary minerals,are generated following igneous intrusion.③Raman analysis suggests that thermally-altered coal possesses the characteristics of both pyrite and coke.Coke from the magma-coal boundary zone possesses the typical characteristics of pyrite.Igneous rock contains a mineral similar to pyrite,confirmed by both having similar Raman peaks.The scattering intensity of Ag indicates that the formation pressure of pyrite increases from thermally-altered coal via the boundary between the coke zone and the igneous rock.
基金This work was supported by the Natural Science Foundation of China(21877049-T.C.,32171296-T.C.,31871006-L.X.,32101044-H.L.)The National Science Fund for Distinguished Young Scholars(82225025-T.C.)+4 种基金University Innovation team project of Guangdong Province(2019KCXTD008)(T.C.)Natural Science Major Project of Guangdong Province(2019KZDXM029)(L.X.)Guangdong Basic and Applied Basic Research Foundation(2021B1515020018-L.X.,2020B1515120043-T.C.)Basic and Applied Basic Research Project of Guangzhou(202002030272-L.X.)China Postdoctoral Science Foundation(2020M681372)(H.L.).
文摘Dear Editor,The COVID-19 pandemic still greatly threatens the public health worldwide and novel vaccines to highly effectively combat SARS-CoV-2 remains an unmet clinical need.However,redox imbalance in immune cells under extra stimulation by vaccine or pathogens greatly dampens the quality of the induced immunity.1 In addition,people infected with COVID-19 that characterized by immune system malfunction were also approved to be attributed by the robust oxidative stress.
基金This work was financially supported by the National Natural Science Foundation of China （Grant Nos. 51562014, 51262009 and 51602135）, the Natural Science Foundation of Jiangxi, China （Grant Nos. 20133ACB20002 and 20142BAB216009）, the Foundation Provincial Department of Education （GJJ150931 and GJJ 150911 ） and the Innovation Training Program of Jingdezhen Ceramic Institute （Grant No. 212050-008）, and partially sponsored by the Foundation of Training Academic and Technical Leaders for Main Majors of Jiangxi （Grant No. 2010DD00800）.
文摘Upconversion （UC） and electrical properties of Na0.5Bi8.5-xErxTi7O27 （NBT-BIT-xEr, 0.00≤x≤0.25） ceramics were studied. Structural analysis revealed that a single inter-growth structured phase exists in all samples and the Er3＋ ion substituting for Bi3＋ at the A-site increases the orthorhombic distortion. Under the 980 nm laser excitation, two characteristic green emission bands and one red emission band were situated at 527, 548 and 670 nm, corresponding to the transitions 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2, respectively. The optimal photoluminescence （PL） were found in the NBT-BIT-0.20Er sample, and the emission color transforms from green to yellowish green. Temperature dependence of fluorescence intensity ratio （FIR） for NBT-BIT-0.20Er was measured ranging from 290 to 440 K and its maximum sensitivity was calculated to be about 0.0020 K-1 at 290 K. Dielectric measurements indicated that Tc slightly increased simultaneously with the decrease of tanS. Therefore, this ceramic has potential applications for high-temperature multifunctional devices.
基金supported by the National Social Science Youth Foundation of China(Project No.20CGL014)the Social Science Planning Project in Chongqing,China(Project No.2021BS084)
文摘The governance effects of directors’and officers’liability insurance(D&O insurance),an important tool for risk diversification,are of strong concern in the capital market.Using a sample of Chinese A-share listed firms from2009 to 2018,we examine the impact of D&O insurance on excess corporate leverage.We find that D&O insurance is negatively associated with excess corporate leverage and that this result is consistent with a series of robustness tests.Further analyses show that D&O insurance impedes excess corporate leverage mainly because of its effect on external monitoring.The effect is more pronounced for firms that are state-owned,have political connections and are located in provinces with low marketization than for other firms.
