The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundam...The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundamental energy conversions.However,whether the dune auroras correspond to atmospheric waves or are associated with magnetospheric dynamics should be determined.This paper reports a dune aurora that occurred during a storm;further,we demonstrate that it was the substructure of the sawtooth aurora that was generated by plasmapause surface waves.Conjugate observations in the magnetospheric source region suggest that the exohiss waves,which are periodically modulated by the plasmapause surface wave-excited ultralow frequency wave,might be responsible for the generation of the dune aurora.Most reported dune aurora events have occurred simultaneously with sawtooth auroras,suggesting that both are plasmapause-driven cross-scale auroral structures.展开更多
We use the High-energy Electron Experiments(HEP)instrument onboard Arase(ERG)to conduct an energy-dependent cross-satellite calibration of electron fluxes measured by the High Energy Particle Detector(HEPD)onboard Fen...We use the High-energy Electron Experiments(HEP)instrument onboard Arase(ERG)to conduct an energy-dependent cross-satellite calibration of electron fluxes measured by the High Energy Particle Detector(HEPD)onboard FengYun-4A(FY-4A)spanning from April 1,2017,to September 30,2019.By tracing the two-dimensional magnetic positions(L,magnetic local time[MLT])of FY-4A at each time,we compare the datasets of the conjugate electron fluxes over the range of 245–894 keV in 6 energy channels for the satellite pair within different sets of L×MLT.The variations in the electron fluxes observed by FY-4A generally agree with the Arase measurements,and the percentages of the ratios of electron flux conjunctions within a factor of 2 are larger than 50%.Compared with Arase,FY-4A systematically overestimates electron fluxes at all 6 energy channels,with the corresponding calibration factors ranging from 0.67 to 0.81.After the cross-satellite calibration,the electron flux conjunctions between FY-4A and Arase show better agreement,with much smaller normalized root mean square errors.Our results provide a valuable reference for the application of FY-4A high-energy electron datasets to in-depth investigations of the Earth’s radiation belt electron dynamics.展开更多
After two decades＇ endeavor, the Research Institute of Petroleum Processing （RIPP） has successfully de- veloped a green caprolactam （CPL） production technology. This technology is based on the integration of tita...After two decades＇ endeavor, the Research Institute of Petroleum Processing （RIPP） has successfully de- veloped a green caprolactam （CPL） production technology. This technology is based on the integration of titanium silicate （TS）-I zeolite with the slurry-bed reactor for the ammoximation of cyclohexanone, the integration of silicalite-1 zeolite with the moving-bed reactor for the gas-phase rearrangement of cyclohex- anone oxime, and the integration of an amorphous nickel （Ni） catalyst with the magnetically stabilized bed reactor for the purification of caprolactam. The world＇s first industrial plant based on this green CPL produc- tion technology has been built and possesses a capacity of 200 kt·a-1. Compared with existing technologies, the plant investment is pronouncedly reduced, and the nitrogen （N） atom utilization is drastically improved. The waste emission is reduced significantly; for example, no ammonium sulfate byproduct is produced. As a result, the price difference between CPL and benzene drops. In 2015, the capacity of the green CPL produc- tion technology reached 3 ×10-6 t·a-1, making China the world＇s largest CPL producer, with a global market share exceeding 50%.展开更多
Blood purification refers to the extra corporeal therapies of removing potentially toxic substances, in which blood is circulated through an adsorption system loading separation materials. High-efficient inexpensive s...Blood purification refers to the extra corporeal therapies of removing potentially toxic substances, in which blood is circulated through an adsorption system loading separation materials. High-efficient inexpensive separation materials are critical to success. In this review, separation materials such as polymers and nanomaterials are summarized and compared. Combining the advantages of the adsorptive membranes and nanomaterials, organic–inorganic hybrid/blend membranes have been developed explosively. These hybrid/blend membranes have both the characteristics of high permeability, easy fabrication, good biocompatibility of adsorptive membranes, and characteristics of fast adsorption rate and high adsorption capacity of nanomaterials. The preparation and modification methodology of the separation materials is reviewed. For affinity separation materials, the relationship of ligand chemistry, ligand density and pores of the matrix is discussed. This paper also summarizes some interesting applications in separation materials for removal of bilirubin, endotoxin, toxic metal ions, cytokine, etc.展开更多
Using wave measurements from the EMFISIS instrument onboard Van Allen Probes,we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss waves.To reproduce these empirical results,we ...Using wave measurements from the EMFISIS instrument onboard Van Allen Probes,we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss waves.To reproduce these empirical results,we establish a fitting model that is a thirdorder polynomial function of L-shell,magnetic local time(MLT),magnetic latitude(MLAT),and AE*.Quantitative comparisons indicate that the model’s fitting functions can reflect favorably the major empirical features of the global distribution of hiss wave intensity,including substorm dependence and the MLT asymmetry.Our results therefore provide a useful analytic model that can be readily employed in future simulations of global radiation belt electron dynamics under the impact of plasmaspheric hiss waves in geospace.展开更多
Purification is a primary application of zone melting, in which the improvement of efficiency, production yield and minimum achievable impurity level are always the research focus due to the increasing demand for high...Purification is a primary application of zone melting, in which the improvement of efficiency, production yield and minimum achievable impurity level are always the research focus due to the increasing demand for high purity metals. This paper has systematically outlined the whole development of related research on zone refining of metals including basic theories, variants of zone refining, parametric optimization, numerical models, and high purity analytical methods. The collection of this information could be of good value to improve the refining efficiency and the production of high purity metals by zone refining.展开更多
We used historical data to trace trapped protons observed by the Fengyun-1C(FY-1C)satellite at low Earth orbits(~800 km)and chose data at 5–10 MeV,10–40 MeV,40–100 MeV,and^100–300 MeV from 25 March to 18 April 200...We used historical data to trace trapped protons observed by the Fengyun-1C(FY-1C)satellite at low Earth orbits(~800 km)and chose data at 5–10 MeV,10–40 MeV,40–100 MeV,and^100–300 MeV from 25 March to 18 April 2000 to analyze the proton variations.Only one isolated strong storm was associated with a solar proton event during this period,and there was no influence from previous proton variations.Complex dynamic phenomena of proton trapping and loss were affected by this disturbance differently depending on the energy and L location.The flux of 5–10 MeV protons increased and created new trapping with a maximum at L^2.0,and the peak flux was significantly higher than that at the center of the South Atlantic Anomaly.However,at higher L,the flux showed obvious loss,with retreat of the outer boundary from L^2.7 to L^2.5.The increase in the 10–40 MeV proton flux was similar to that of the 5–10 MeV flux;however,the peak flux intensity was lower than that at the center of the South Atlantic Anomaly.The loss of the 10–40 MeV proton flux was closer to the Earth side,and the outer boundary was reduced from L^2.3 to L^2.25.For the higher energy protons of 40–100 MeV and 100–300 MeV,no new trapping was found.Loss of the 40–100 MeV protons was observed,and the outer boundary shifted from L^2.0 to L^1.9.Loss was not obvious for the 100–400 MeV protons,which were distributed within L<1.8.New proton trapping was more likely to be created at lower energy in the region of solar proton injection by the strong magnetic storm,whereas loss occurred in a wide energy range and reduced the outer boundary on the Earth side.Similar dynamic changes were observed by the NOAA-15 satellite in the same period,but the FY-1C satellite observed more complex changes in lower energy protons.These results revealed that the dynamic behavior of protons with different L-shells was due to differences in the pitch angle.Possible mechanisms related to new trapping and loss are also discussed.These mechanisms are very important for understanding the behavior of the proton belt in the coming solar cycle.展开更多
The plasmapause locations determined from the Chang'e-3(CE-3) Extreme Ultraviolet Camera(EUVC) images and the auroral boundaries determined from the Defense Meteorological Satellite Program(DMSP) Special Sensor Ul...The plasmapause locations determined from the Chang'e-3(CE-3) Extreme Ultraviolet Camera(EUVC) images and the auroral boundaries determined from the Defense Meteorological Satellite Program(DMSP) Special Sensor Ultraviolet Spectrographic Imager(SSUSI) images are used to investigate the plasmaspheric evolutions during substorms. The most important finding is a nightside pointing plasmaspheric plume observed at 23:05 UT on 21 April 2014 under quiet solar wind and geomagnetic conditions, which drifted from the dusk sector. High correlations between the plasmapause evolutions and the auroral signatures exist during substorms. After substorm onset, the plasmapause erosion and the equatorward expansion of the auroral oval occur almost simultaneously in both MLT and UT, and then both the erosion and the expansion propagate westward and eastward. It is suggested that the plasmaspheric erosion and its MLT propagations are induced by the enhanced earthward plasma convection during substorm period, and the substorm dipolarization causes pitch-angle scattering of plasma sheet electrons and the resulting precipitation excites aurora emissions at the same time.展开更多
New observations of auroras based on the wide-field aurora imager(WAI)onboard Fengyun-3D(FY-3D)satellite are exhibited in this paper.Validity of the WAI data is analyzed by comparing auroral boundaries derived from WA...New observations of auroras based on the wide-field aurora imager(WAI)onboard Fengyun-3D(FY-3D)satellite are exhibited in this paper.Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager(SSUSI)aboard the Defense Meteorological Satellite Program(DMSP F18).Dynamic variations of the aurora with the solar wind,interplanetary magnetic field(IMF)parameters,and the SYM-H index are also investigated.The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics.Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth’s space weather.Since the configuration of aurora is a good indicator of the solar wind–magnetosphere–ionosphere(SW-M-I)coupling system,and can reflect the disturbance of the space environment,the WAI will provide important data to help us to study the physical processes in space.展开更多
Extreme ultraviolet(EUV)observations are widely used in solar activity research and space weather forecasting since they can observe both the solar eruptions and the source regions of the solar wind.Flat field process...Extreme ultraviolet(EUV)observations are widely used in solar activity research and space weather forecasting since they can observe both the solar eruptions and the source regions of the solar wind.Flat field processing is indispensable to remove the instrumental non-uniformity of a solar EUV imager in producing high-quality scientific data from original observed data.FengYun-3E(FY-3E)is a meteorological satellite operated in a Sunsynchronous orbit,and the routine EUV imaging data from the Solar X-ray and Extreme Ultraviolet Imager(X-EUVI)onboard FY-3E has the characteristic of concentric rotation.Taking advantage of the concentric rotation,we propose a post-hoc flat field measurement method for its EUV 195A channel in this paper.This method removes the small-scale and time-varying component of coronal activities by taking the median value for each pixel along the time axis of a concentric rotation data cube,and then derives the large-scale and invariable component of the quiet coronal radiation,and finally generates a flat field image.The flat field can be generated with cadences from hundreds of minutes(one orbit)to several days.Higher flat field accuracy can be achieved by employing more data.Further analysis shows that our method is able to measure the instrumental spot-like nonuniformity possibly caused by contamination on the detector,which mostly disappears after the in-orbit selfcleaning process.It can also measure the quasi-periodic grid-like non-uniformity,possibly from the obscuration of the support mesh on the rear filter.After flat field correction,these instrumental non-uniformities from the original data are effectively removed.Moreover,the X-EUVI 195A data after dark and flat field corrections are consistent with the 193A imaging data from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory,verifying the suitability of the method.The post-hoc method does not occupy observation time,which is advantageous for space weather operations.Our method is not only suitable for FY-3E/X-EUVI but also a candidate method for the flat field measurement of future solar EUV telescopes.展开更多
Mineralized tissue regeneration is an important and challenging part of the field of tissue engineering and regeneration.At present,autograft harvest procedures may cause secondary trauma to patients,while bone scaffo...Mineralized tissue regeneration is an important and challenging part of the field of tissue engineering and regeneration.At present,autograft harvest procedures may cause secondary trauma to patients,while bone scaffold materials lack osteogenic activity,resulting in a limited application.Loaded with osteogenic induction growth factor can improve the osteoinductive performance of bone graft,but the explosive release of growth factor may also cause side effects.In this study,we innovatively used platelet-rich fibrin(PRF)-modified bone scaffolds(Bio-Oss®)to replace autograft,and used cytokine(BMP-2)to enhance osteogenesis.Encouragingly,this mixture,which we named“Autograft Mimic(AGM)”,has multiple functions and advantages.(1)The fiber network provided by PRF binds the entire bone scaffold together,thereby shaping the bone grafts and maintaining the space of the defect area.(2)The sustained release of BMP-2 from bone graft promoted bone regeneration continuously.(3)AGM recruited bone marrow mesenchymal stem cells(BMSCs)and promote their proliferation,migration,and osteogenic differentiation.Thus,AGM developed in this study can improve osteogenesis,and provide new guidance for the development of clinical bone grafts.展开更多
China＇s tariff arrangement in the transition period after ＂entry to WTO＂ influences the process of the multilateral trade system in the world. Establishing the free trade area and customs union according to WTO/GAT...China＇s tariff arrangement in the transition period after ＂entry to WTO＂ influences the process of the multilateral trade system in the world. Establishing the free trade area and customs union according to WTO/GATS 1994 article 24, or according to authorizing the clause （Enabling Clause ） to sign the regional trade agreement between developing countries or signed the protocol of economic integration taking promoting and serving the liberalization of trade as purpose according to WTO/GATS article 5, include the regional trade agreement in the multilateral trade system frame to standardize, supervise and coordinate to China, reduce trade protectionism and improve the multilateral trade system＇s influence in the world greatly. Drawing lessons from CEPA and China the system of the manoeuvre ahead of time of overall ＂entry to WTO＂ of ASEAN Free Trade Area and arrange, accelerate multilateral regional cooperation in economy and trade, zero tariff scheme reform favors route choice.展开更多
Considering the earth powered by intermittent renewable energy in the coming future,solid oxide electrolysis cell(SOEC)will play an indispensable role in efficient energy conversion and storage on demand.The thermolyt...Considering the earth powered by intermittent renewable energy in the coming future,solid oxide electrolysis cell(SOEC)will play an indispensable role in efficient energy conversion and storage on demand.The thermolytic and kinetic merits grant SOEC a bright potential to be directly integrated with electrical grid and downstream chemical synthesis process.Meanwhile,the scientific community are still endeavoring to pursue the SOEC assembled with better materials and operated at a more energy-efficient way.In this review article,at cell level,we focus on the recent development of electrolyte,cathode,anode and buffer layer materials for both steam and CO_(2)electrolysis.On the other hand,we also discuss the next generation SOEC operated with the assistant of other fuels to further reduce the energy consumption and enhance the productivity of the electrolyzer.And stack level,the sealant,interconnect and stack operation strategies are collectively covered.Finally,the challenges and future research direction in SOECs are included.展开更多
Developing efficient and stable zeolites for vapor-phase Beckmann rearrangement of cyclohexanone oxime is still a great challenge to realizeε-caprolactam(CPL)green production.In this work,the hierarchical porous sili...Developing efficient and stable zeolites for vapor-phase Beckmann rearrangement of cyclohexanone oxime is still a great challenge to realizeε-caprolactam(CPL)green production.In this work,the hierarchical porous silicalite-1 zeolites with multiple hollow structure(S-1-M)are explored by in-situ desilication−recrystallization post-treatment of spongy highway-like zeolites(S-1-S),which are synthesized through silanization synthesis of conventional bulky silicalite-1(S-1).Compared to S-1,S-1-M achieves superior catalytic performance,with improving the CPL selectivity from 85.7%to 94.1%and prolonging the catalyst lifetime from 74 to 126 h at a weight hourly space velocity(WHSV)of 6 h^(−1).Comprehensive physiochemical studies demonstrate that the highly dispersed intracrystalline cavities within S-1-M endow greater mass diffusion and better quasi acidity inducing by the enhanced H-bonds among abundant H-bonded silanols,which is cooperatively responsible for its superior catalytic performance.展开更多
Atrial fibrillation(AF)is a frequent arrhythmia associated with cardiovascular morbidity and mortality.Neutrophil extracellular traps(NETs)are DNA fragments with cytoplasm proteins released from neutrophils,which are ...Atrial fibrillation(AF)is a frequent arrhythmia associated with cardiovascular morbidity and mortality.Neutrophil extracellular traps(NETs)are DNA fragments with cytoplasm proteins released from neutrophils,which are involved in various cardiovascular diseases.To elucidate the role of NETs in AF,we investigated the effect of NETs on AF progression and the secretion of NETs in AF.Results showed that:NETs induced the autophagic apoptosis of cardiomyocytes,and NETs also led to mitochondrial injury by promoting mitochondrial depolarization and ROS production.Ongoing tachy-pacing led to the structural loss of cardiomyocytes and provided potent stimuli to induce NETs secretion from neutrophils.In the meanwhile,increased Ang II in AF facilitated NETs formation through the upregulation of AKT phosphorylation,while it could not directly initiate NETosis as the autophagy was not induced.In vivo,DNase I was administrated to abrogate NETs formation,and AF-related fibrosis was ameliorated as expected.Correspondingly,the duration of the induced AF was reduced.Our study addresses the formation mechanism of NETs in AF and demonstrates the lethal effects of NETs on cardiomyocytes through the induction of mitochondrial injury and autophagic cell death,which comprehensively describes the positive feedback comprised of NETs and stimuli secreted by cardiomyocytes that sustains the progression of AF and AF related fibrosis.展开更多
Highly competent and economical photocatalysts are one of the most charming targets in environmental restoration and clean production.Herein,a novel sulfur-vacancy-rich Bi/Bi_(2)S_(3)/SnS_(2)Z-scheme heterostruc-ture ...Highly competent and economical photocatalysts are one of the most charming targets in environmental restoration and clean production.Herein,a novel sulfur-vacancy-rich Bi/Bi_(2)S_(3)/SnS_(2)Z-scheme heterostruc-ture was constructed in situ and applied for the photoreduction Cr(VI)and nitrogen fixation.The fab-ricated Bi/Bi_(2)S_(3)/SnS_(2)-2 exhibits the optimum photoreduction Cr(VI)performance with the efficiency of 94.5%within 15 min visible light irradiation.The remarkably enhanced catalytic efficiency derived from the synergistic effect of the construction of intimate contacted interface,abundant sulfur vacancy and surface plasmon resonance(SPR)effect of metal Bi.Meanwhile,the excellent photocatalytic nitrogen fix-ation property(96.4μmol g^(-1)h^(-1))was achieved by Bi/Bi_(2)S_(3)/SnS_(2)-2 under full solar illumination because sulfur vacancy could provide sufficient catalytic sites to accelerate the adsorption and nitrogen activation.The Z-scheme heterostructure was proposed to expound the photocatalytic mechanism.This work offers a new perspective on hierarchical heterostructure with plentiful vacancies for environmental remediation and energy development.展开更多
基金supported by the National Natural Science Foundation of China(42222408,41931073)supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y2021027)supported by the Key Research Program of the Institute of Geology&Geophysics,Chinese Academy of Sciences(grant IGGCAS-201904).
文摘The dune aurora,at a scale of~30 kilometers,was reported recently using ground camera.The small-scale dune aurora occurs on the duskside and exhibits a monochromatic oscillation in the auroral emission,implying fundamental energy conversions.However,whether the dune auroras correspond to atmospheric waves or are associated with magnetospheric dynamics should be determined.This paper reports a dune aurora that occurred during a storm;further,we demonstrate that it was the substructure of the sawtooth aurora that was generated by plasmapause surface waves.Conjugate observations in the magnetospheric source region suggest that the exohiss waves,which are periodically modulated by the plasmapause surface wave-excited ultralow frequency wave,might be responsible for the generation of the dune aurora.Most reported dune aurora events have occurred simultaneously with sawtooth auroras,suggesting that both are plasmapause-driven cross-scale auroral structures.
基金supported by the National Natural Science Foundation of China(Grant Nos.42025404,42188101,42241143,41931073,and 42204160)the National Key R&D Program of China(Grant Nos.2022YFF0503700,2022YFF0503900,and 2021YFA0718600)+1 种基金the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)the Fundamental Research Funds for the Central Universities(Grant Nos.2042022kf1012 and 2042022kf1016).
文摘We use the High-energy Electron Experiments(HEP)instrument onboard Arase(ERG)to conduct an energy-dependent cross-satellite calibration of electron fluxes measured by the High Energy Particle Detector(HEPD)onboard FengYun-4A(FY-4A)spanning from April 1,2017,to September 30,2019.By tracing the two-dimensional magnetic positions(L,magnetic local time[MLT])of FY-4A at each time,we compare the datasets of the conjugate electron fluxes over the range of 245–894 keV in 6 energy channels for the satellite pair within different sets of L×MLT.The variations in the electron fluxes observed by FY-4A generally agree with the Arase measurements,and the percentages of the ratios of electron flux conjunctions within a factor of 2 are larger than 50%.Compared with Arase,FY-4A systematically overestimates electron fluxes at all 6 energy channels,with the corresponding calibration factors ranging from 0.67 to 0.81.After the cross-satellite calibration,the electron flux conjunctions between FY-4A and Arase show better agreement,with much smaller normalized root mean square errors.Our results provide a valuable reference for the application of FY-4A high-energy electron datasets to in-depth investigations of the Earth’s radiation belt electron dynamics.
文摘After two decades＇ endeavor, the Research Institute of Petroleum Processing （RIPP） has successfully de- veloped a green caprolactam （CPL） production technology. This technology is based on the integration of titanium silicate （TS）-I zeolite with the slurry-bed reactor for the ammoximation of cyclohexanone, the integration of silicalite-1 zeolite with the moving-bed reactor for the gas-phase rearrangement of cyclohex- anone oxime, and the integration of an amorphous nickel （Ni） catalyst with the magnetically stabilized bed reactor for the purification of caprolactam. The world＇s first industrial plant based on this green CPL produc- tion technology has been built and possesses a capacity of 200 kt·a-1. Compared with existing technologies, the plant investment is pronouncedly reduced, and the nitrogen （N） atom utilization is drastically improved. The waste emission is reduced significantly; for example, no ammonium sulfate byproduct is produced. As a result, the price difference between CPL and benzene drops. In 2015, the capacity of the green CPL produc- tion technology reached 3 ×10-6 t·a-1, making China the world＇s largest CPL producer, with a global market share exceeding 50%.
基金Supported by the National Natural Science Foundation of China(No.21606120)National Undergraducate Training Program for Innovation and Entrepreneurship(Nos.201710148000016 and 201810148080)
文摘Blood purification refers to the extra corporeal therapies of removing potentially toxic substances, in which blood is circulated through an adsorption system loading separation materials. High-efficient inexpensive separation materials are critical to success. In this review, separation materials such as polymers and nanomaterials are summarized and compared. Combining the advantages of the adsorptive membranes and nanomaterials, organic–inorganic hybrid/blend membranes have been developed explosively. These hybrid/blend membranes have both the characteristics of high permeability, easy fabrication, good biocompatibility of adsorptive membranes, and characteristics of fast adsorption rate and high adsorption capacity of nanomaterials. The preparation and modification methodology of the separation materials is reviewed. For affinity separation materials, the relationship of ligand chemistry, ligand density and pores of the matrix is discussed. This paper also summarizes some interesting applications in separation materials for removal of bilirubin, endotoxin, toxic metal ions, cytokine, etc.
基金supported by the National Basic Research Program of China (‘‘973’’ Program, No. 2013CB035906)the National Natural Science Foundation of China (No. 51439005)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No. 51621092)
基金supported by the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000)the NSFC grants 41674163, 41974186, 41704162, 41904144, and 41904143+1 种基金the pre-research projects on Civil Aerospace Technologies No. D020308, D020104 and D020303funded by China National Space Administration。
文摘Using wave measurements from the EMFISIS instrument onboard Van Allen Probes,we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss waves.To reproduce these empirical results,we establish a fitting model that is a thirdorder polynomial function of L-shell,magnetic local time(MLT),magnetic latitude(MLAT),and AE*.Quantitative comparisons indicate that the model’s fitting functions can reflect favorably the major empirical features of the global distribution of hiss wave intensity,including substorm dependence and the MLT asymmetry.Our results therefore provide a useful analytic model that can be readily employed in future simulations of global radiation belt electron dynamics under the impact of plasmaspheric hiss waves in geospace.
文摘Purification is a primary application of zone melting, in which the improvement of efficiency, production yield and minimum achievable impurity level are always the research focus due to the increasing demand for high purity metals. This paper has systematically outlined the whole development of related research on zone refining of metals including basic theories, variants of zone refining, parametric optimization, numerical models, and high purity analytical methods. The collection of this information could be of good value to improve the refining efficiency and the production of high purity metals by zone refining.
文摘We used historical data to trace trapped protons observed by the Fengyun-1C(FY-1C)satellite at low Earth orbits(~800 km)and chose data at 5–10 MeV,10–40 MeV,40–100 MeV,and^100–300 MeV from 25 March to 18 April 2000 to analyze the proton variations.Only one isolated strong storm was associated with a solar proton event during this period,and there was no influence from previous proton variations.Complex dynamic phenomena of proton trapping and loss were affected by this disturbance differently depending on the energy and L location.The flux of 5–10 MeV protons increased and created new trapping with a maximum at L^2.0,and the peak flux was significantly higher than that at the center of the South Atlantic Anomaly.However,at higher L,the flux showed obvious loss,with retreat of the outer boundary from L^2.7 to L^2.5.The increase in the 10–40 MeV proton flux was similar to that of the 5–10 MeV flux;however,the peak flux intensity was lower than that at the center of the South Atlantic Anomaly.The loss of the 10–40 MeV proton flux was closer to the Earth side,and the outer boundary was reduced from L^2.3 to L^2.25.For the higher energy protons of 40–100 MeV and 100–300 MeV,no new trapping was found.Loss of the 40–100 MeV protons was observed,and the outer boundary shifted from L^2.0 to L^1.9.Loss was not obvious for the 100–400 MeV protons,which were distributed within L<1.8.New proton trapping was more likely to be created at lower energy in the region of solar proton injection by the strong magnetic storm,whereas loss occurred in a wide energy range and reduced the outer boundary on the Earth side.Similar dynamic changes were observed by the NOAA-15 satellite in the same period,but the FY-1C satellite observed more complex changes in lower energy protons.These results revealed that the dynamic behavior of protons with different L-shells was due to differences in the pitch angle.Possible mechanisms related to new trapping and loss are also discussed.These mechanisms are very important for understanding the behavior of the proton belt in the coming solar cycle.
基金supported by National Natural Science Foundation of China (41674155 and 41274147)Youth Innovation Promotion Association of Chinese Academy of Sciences (No.2017258)Key Research Project of Chinese Academy of Sciences:Application Research on the Scientific Data from Chang’E-3 Mission (KGZD-EW-603)
文摘The plasmapause locations determined from the Chang'e-3(CE-3) Extreme Ultraviolet Camera(EUVC) images and the auroral boundaries determined from the Defense Meteorological Satellite Program(DMSP) Special Sensor Ultraviolet Spectrographic Imager(SSUSI) images are used to investigate the plasmaspheric evolutions during substorms. The most important finding is a nightside pointing plasmaspheric plume observed at 23:05 UT on 21 April 2014 under quiet solar wind and geomagnetic conditions, which drifted from the dusk sector. High correlations between the plasmapause evolutions and the auroral signatures exist during substorms. After substorm onset, the plasmapause erosion and the equatorward expansion of the auroral oval occur almost simultaneously in both MLT and UT, and then both the erosion and the expansion propagate westward and eastward. It is suggested that the plasmaspheric erosion and its MLT propagations are induced by the enhanced earthward plasma convection during substorm period, and the substorm dipolarization causes pitch-angle scattering of plasma sheet electrons and the resulting precipitation excites aurora emissions at the same time.
基金the National Science Foundation of China(41327802,41774152 and 41674155)in part by Youth Innovation Promotion Association of the Chinese Academy of Sciences(2017258)the Strategic Priority Program on Space Science,Chinese Academy of Sciences,Grant No.XDA15350203。
文摘New observations of auroras based on the wide-field aurora imager(WAI)onboard Fengyun-3D(FY-3D)satellite are exhibited in this paper.Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager(SSUSI)aboard the Defense Meteorological Satellite Program(DMSP F18).Dynamic variations of the aurora with the solar wind,interplanetary magnetic field(IMF)parameters,and the SYM-H index are also investigated.The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics.Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth’s space weather.Since the configuration of aurora is a good indicator of the solar wind–magnetosphere–ionosphere(SW-M-I)coupling system,and can reflect the disturbance of the space environment,the WAI will provide important data to help us to study the physical processes in space.
基金supported by the National Key R&D Program of China(2021YFA0718600)the National Natural Science Foundations of China(NSFC,Grant Nos.41931073,41774195)+2 种基金Ten-thousand Talents Program of JingSong Wang,and the Specialized Research Fund for State Key Laboratoriessupported by the Strategic Priority Research Program of the Chinese Academy of Sciences,Grant No.XDA 15018400supported by the China Postdoctoral Science Foundation(2021M700246)。
文摘Extreme ultraviolet(EUV)observations are widely used in solar activity research and space weather forecasting since they can observe both the solar eruptions and the source regions of the solar wind.Flat field processing is indispensable to remove the instrumental non-uniformity of a solar EUV imager in producing high-quality scientific data from original observed data.FengYun-3E(FY-3E)is a meteorological satellite operated in a Sunsynchronous orbit,and the routine EUV imaging data from the Solar X-ray and Extreme Ultraviolet Imager(X-EUVI)onboard FY-3E has the characteristic of concentric rotation.Taking advantage of the concentric rotation,we propose a post-hoc flat field measurement method for its EUV 195A channel in this paper.This method removes the small-scale and time-varying component of coronal activities by taking the median value for each pixel along the time axis of a concentric rotation data cube,and then derives the large-scale and invariable component of the quiet coronal radiation,and finally generates a flat field image.The flat field can be generated with cadences from hundreds of minutes(one orbit)to several days.Higher flat field accuracy can be achieved by employing more data.Further analysis shows that our method is able to measure the instrumental spot-like nonuniformity possibly caused by contamination on the detector,which mostly disappears after the in-orbit selfcleaning process.It can also measure the quasi-periodic grid-like non-uniformity,possibly from the obscuration of the support mesh on the rear filter.After flat field correction,these instrumental non-uniformities from the original data are effectively removed.Moreover,the X-EUVI 195A data after dark and flat field corrections are consistent with the 193A imaging data from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory,verifying the suitability of the method.The post-hoc method does not occupy observation time,which is advantageous for space weather operations.Our method is not only suitable for FY-3E/X-EUVI but also a candidate method for the flat field measurement of future solar EUV telescopes.
基金the National Natural Science Foundation of China(Grant No.82071095,31570982).
文摘Mineralized tissue regeneration is an important and challenging part of the field of tissue engineering and regeneration.At present,autograft harvest procedures may cause secondary trauma to patients,while bone scaffold materials lack osteogenic activity,resulting in a limited application.Loaded with osteogenic induction growth factor can improve the osteoinductive performance of bone graft,but the explosive release of growth factor may also cause side effects.In this study,we innovatively used platelet-rich fibrin(PRF)-modified bone scaffolds(Bio-Oss®)to replace autograft,and used cytokine(BMP-2)to enhance osteogenesis.Encouragingly,this mixture,which we named“Autograft Mimic(AGM)”,has multiple functions and advantages.(1)The fiber network provided by PRF binds the entire bone scaffold together,thereby shaping the bone grafts and maintaining the space of the defect area.(2)The sustained release of BMP-2 from bone graft promoted bone regeneration continuously.(3)AGM recruited bone marrow mesenchymal stem cells(BMSCs)and promote their proliferation,migration,and osteogenic differentiation.Thus,AGM developed in this study can improve osteogenesis,and provide new guidance for the development of clinical bone grafts.
文摘China＇s tariff arrangement in the transition period after ＂entry to WTO＂ influences the process of the multilateral trade system in the world. Establishing the free trade area and customs union according to WTO/GATS 1994 article 24, or according to authorizing the clause （Enabling Clause ） to sign the regional trade agreement between developing countries or signed the protocol of economic integration taking promoting and serving the liberalization of trade as purpose according to WTO/GATS article 5, include the regional trade agreement in the multilateral trade system frame to standardize, supervise and coordinate to China, reduce trade protectionism and improve the multilateral trade system＇s influence in the world greatly. Drawing lessons from CEPA and China the system of the manoeuvre ahead of time of overall ＂entry to WTO＂ of ASEAN Free Trade Area and arrange, accelerate multilateral regional cooperation in economy and trade, zero tariff scheme reform favors route choice.
基金supported financially by the National Key Research&Development Program of China(No.2018YFE0124700)the National Natural Science Foundation of China(Nos.22272136,22102135,22202041,22172129,52072134,U1910209,51876181 and 51972128)+2 种基金Science and Technology Projects of Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM)(No.HRTP-[2022]-23)and Hubei Province(Nos.2021CBA149 and 2021CFA072)the financial support from Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515010069 and 2020A1515110904)the Natural Science Foundation of Fujian Province(No.2021J01212759)。
文摘Considering the earth powered by intermittent renewable energy in the coming future,solid oxide electrolysis cell(SOEC)will play an indispensable role in efficient energy conversion and storage on demand.The thermolytic and kinetic merits grant SOEC a bright potential to be directly integrated with electrical grid and downstream chemical synthesis process.Meanwhile,the scientific community are still endeavoring to pursue the SOEC assembled with better materials and operated at a more energy-efficient way.In this review article,at cell level,we focus on the recent development of electrolyte,cathode,anode and buffer layer materials for both steam and CO_(2)electrolysis.On the other hand,we also discuss the next generation SOEC operated with the assistant of other fuels to further reduce the energy consumption and enhance the productivity of the electrolyzer.And stack level,the sealant,interconnect and stack operation strategies are collectively covered.Finally,the challenges and future research direction in SOECs are included.
基金the National Key Basic Research Development Plan“973”Project(No.2006CB202508)the National Key R&D Program of China(No.2021YFA1502600)+2 种基金State Key Laboratory of Catalytic Materials and Reaction Engineering(RIPP,SINOPEC)(No.33600000-20-ZC0607-0024)the SINOPEC Project(Nos.411058 and 413025)the National Natural Science Foundation(Nos.21808244,22178347,and 22072182).
文摘Developing efficient and stable zeolites for vapor-phase Beckmann rearrangement of cyclohexanone oxime is still a great challenge to realizeε-caprolactam(CPL)green production.In this work,the hierarchical porous silicalite-1 zeolites with multiple hollow structure(S-1-M)are explored by in-situ desilication−recrystallization post-treatment of spongy highway-like zeolites(S-1-S),which are synthesized through silanization synthesis of conventional bulky silicalite-1(S-1).Compared to S-1,S-1-M achieves superior catalytic performance,with improving the CPL selectivity from 85.7%to 94.1%and prolonging the catalyst lifetime from 74 to 126 h at a weight hourly space velocity(WHSV)of 6 h^(−1).Comprehensive physiochemical studies demonstrate that the highly dispersed intracrystalline cavities within S-1-M endow greater mass diffusion and better quasi acidity inducing by the enhanced H-bonds among abundant H-bonded silanols,which is cooperatively responsible for its superior catalytic performance.
基金This work was supported by the National Natural Science Foundation of China(No.81900311,82100336,82004154,and 81970345)Support Plan of Science and Technology Department of Sichuan Province,China(2022NSFSC1395 and 2022YFS0364)+1 种基金China Postdoctoral Science Foundation(2021M692282)West China hospital Postdoctoral Science Foundation(20HXBH171).
文摘Atrial fibrillation(AF)is a frequent arrhythmia associated with cardiovascular morbidity and mortality.Neutrophil extracellular traps(NETs)are DNA fragments with cytoplasm proteins released from neutrophils,which are involved in various cardiovascular diseases.To elucidate the role of NETs in AF,we investigated the effect of NETs on AF progression and the secretion of NETs in AF.Results showed that:NETs induced the autophagic apoptosis of cardiomyocytes,and NETs also led to mitochondrial injury by promoting mitochondrial depolarization and ROS production.Ongoing tachy-pacing led to the structural loss of cardiomyocytes and provided potent stimuli to induce NETs secretion from neutrophils.In the meanwhile,increased Ang II in AF facilitated NETs formation through the upregulation of AKT phosphorylation,while it could not directly initiate NETosis as the autophagy was not induced.In vivo,DNase I was administrated to abrogate NETs formation,and AF-related fibrosis was ameliorated as expected.Correspondingly,the duration of the induced AF was reduced.Our study addresses the formation mechanism of NETs in AF and demonstrates the lethal effects of NETs on cardiomyocytes through the induction of mitochondrial injury and autophagic cell death,which comprehensively describes the positive feedback comprised of NETs and stimuli secreted by cardiomyocytes that sustains the progression of AF and AF related fibrosis.
基金supported by the National Natural Science Foun-dation of China(Nos.22178038 and 21878031)Innovation Supporting Plan for High-level Talents of Dalian(No.2021RQ116).
文摘Highly competent and economical photocatalysts are one of the most charming targets in environmental restoration and clean production.Herein,a novel sulfur-vacancy-rich Bi/Bi_(2)S_(3)/SnS_(2)Z-scheme heterostruc-ture was constructed in situ and applied for the photoreduction Cr(VI)and nitrogen fixation.The fab-ricated Bi/Bi_(2)S_(3)/SnS_(2)-2 exhibits the optimum photoreduction Cr(VI)performance with the efficiency of 94.5%within 15 min visible light irradiation.The remarkably enhanced catalytic efficiency derived from the synergistic effect of the construction of intimate contacted interface,abundant sulfur vacancy and surface plasmon resonance(SPR)effect of metal Bi.Meanwhile,the excellent photocatalytic nitrogen fix-ation property(96.4μmol g^(-1)h^(-1))was achieved by Bi/Bi_(2)S_(3)/SnS_(2)-2 under full solar illumination because sulfur vacancy could provide sufficient catalytic sites to accelerate the adsorption and nitrogen activation.The Z-scheme heterostructure was proposed to expound the photocatalytic mechanism.This work offers a new perspective on hierarchical heterostructure with plentiful vacancies for environmental remediation and energy development.
