To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitro...To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.展开更多
The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and...The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and beyond.Herein,by learning from the pencil-writing process,a facile solid-ink rubbing technology(SIR-tech)is invented to address the above challenge.The solid-ink is exampled by rational combination of liquid metal and graphite particles.By harnessing the synergistic effects between rubbing and adhesion,controllable metallic skin is successfully formed onto metals,woods,ceramics,and plastics without limitation in size and shape.Moreover,outperforming pure liquid-metal coating,the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing.The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well.For applications,the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils.Meanwhile,advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from-196 to 120℃.This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.展开更多
This study is the first systematic assessment of the Lower Ordovician microbial carbonates in Songzi,Hubei Province,China.This paper divides the microbial carbonates into two types according to growth patterns,namely ...This study is the first systematic assessment of the Lower Ordovician microbial carbonates in Songzi,Hubei Province,China.This paper divides the microbial carbonates into two types according to growth patterns,namely nongranular and granular.The nongranular types include stromatolites,thrombolites,dendrolites,leiolites and laminites;the granular types are mainly oncolites and may include a small amount of microbiogenic oolite.According to their geometric features,the stromatolites can be divided into four types:stratiform,wavy,columnar and domal.Additionally,dipyramidal columnar stromatolites are identified for the first time and represent a new type of columnar stromatolite.The thrombolites are divided into three types:speckled,reticulated and banded.The grazing gastropod Ecculiomphalus and traces of bioturbation are observed in the speckled and reticulated thrombolites.This paper considers these two kinds of thrombolites to represent bioturbated thrombolites.These findings not only fill gaps in the field of domestic Ordovician bioturbated thrombolites but also provide new information for the study of thrombolites.Based on the analysis of the sedimentary characteristics of microbialites,the depositional environments of the various types of microbialites are described,and the distribution patterns of their depositional environments are summarized.The relationship between the development of microbialites and the evolution and radiation of metazoans during the Early to Middle Ordovician is discussed.Consistent with the correspondence between the stepwise and rapid radiation of metazoans and the abrupt reduction in the number of microbialites between the late Early Ordovician and the early Middle Ordovician,fossils of benthonic grazing gastropods(Ecculiomphalus)were found in the stromatolites and thrombolite of the study area.It is believed that the gradual reduction in microbialites was related to the rapid increase in the abundance of metazoans.Grazers not only grazed on the microorganisms that formed stromatolites,resulting in a continuous reduction in the number of stromatolites,but also disrupted the growth state of the stromatolites,resulting in the formation of unique bioturbated thrombolites in the study area.Hydrocarbon potential analysis shows that the microbialites in the Nanjinguan Formation represent better source rocks than those in the other formations.展开更多
On May 21,2021,an MS6.4 earthquake occurred in Yangbi,Yunnan province,China,which exhibited typical foreshock-mainshock-aftershock characteristics.To better understand the velocity structure of the focal area and adja...On May 21,2021,an MS6.4 earthquake occurred in Yangbi,Yunnan province,China,which exhibited typical foreshock-mainshock-aftershock characteristics.To better understand the velocity structure of the focal area and adjacent fault zones,Pg/Sg travel times at 12 seismic stations for the local earthquakes with ML≥1.5 from 2009-2019 and the Yangbi sequence in May of 2021 were used to invert the three-dimensional(3D)structures for both vP and v_(P)/v_(S).The obtained structure extends deeply to 15 km for area(25°N-26.5°N,99.5°E-101°E)at a horizontal resolution of 10×10 km,and the accuracy of the v_(P) velocity was verified using airgun signals excited by the Binchuan Airgun Transmitting Seismic Station(BATSS).The resulting v_(P) and v^(P)/v_(S) images correlate with existing fault zones and the Yangbi sequence,including:(1)The shallow velocity structure at 0 km agrees with local topography,where the Binchuan basin exhibits low-v_(P) and high-v_(P)/v_(S) values.From 3-15 km,v_(P) and v_(P)/v_(S) show variations,and the boundaries are consistent with the main faults(e.g.,the Weixi-Qiaohou-Weishan,Honghe,and Chenghai faults).(2)The largest foreshock(M_(S)5.6),main-shock(MS6.4),and largest aftershock(M_(S)5.2)occurred near the boundaries where both vP and v_(P)/v_(S) have clear contrasts.(3)Small earthquakes are also concentrated in the transition zone between high-and low-vP and v_(P)/v_(S) anomalies,and are biased toward low-v_(P)/v_(S) zones.(4)Boundaries in v_(P) and v_(P)/v_(S) are observed at 20 km west of the Weixi-Qiaohou-Weishan fault,indicating that there may exist one hidden fault.展开更多
A M_(S)6.4 earthquake occurred on 21 May 2021 in Yangbi county,Dali prefecture,Yunnan,China,at 21:48 Beijing Time(13:48 UTC).Earthquakes with an M3.0 or higher occurred before and after the main shock.Seismic data ana...A M_(S)6.4 earthquake occurred on 21 May 2021 in Yangbi county,Dali prefecture,Yunnan,China,at 21:48 Beijing Time(13:48 UTC).Earthquakes with an M3.0 or higher occurred before and after the main shock.Seismic data analysis is essential for the in-depth investigation of the 2021 Yangbi M_(S)6.4 earthquake sequence and the seismotectonics of northwestern Yunnan.Institute of Geophysics,China Earthquake Administration(CEA),has compiled a dataset of seismological observations from 157 broadband stations located within 500 km of the epicenter,and has made this dataset available to the earthquake science research community.The dataset(total file size:329 GB)consists of event waveforms with a sampling frequency of 100 sps collected from 18 to 28 May 2021,20-Hz and 100-Hz continuous waveforms collected from 12 to 31 May 2021,and seismic instrument response files.To promote data sharing,the dataset also includes the seismic event waveforms from 20 to 22 May 2021 recorded at 50 stations of the ongoing Binchuan Active Source Geophysical Observation Project,for which the data protection period has not expired.Sample waveforms of the main shock are included in the appendix of this article and can be downloaded from the Earthquake Science website.The event and continuous waveforms are available from the Earthquake Science Data Center website(www.esdc.ac.cn)on application.展开更多
The relative contribution of long-distance dispersal and local diffusion in the spread of invasive species has been a subject of much debate. Invasion of the intertidal mudflats by Spartina alterniflora is an ideal ex...The relative contribution of long-distance dispersal and local diffusion in the spread of invasive species has been a subject of much debate. Invasion of the intertidal mudflats by Spartina alterniflora is an ideal example of stratified diffusion, involving both long-distance dispersal of seeds and local diffusion due to clonal growth. In conjunction with experimental data on range radius-versus-time curve, a traveling wave equation-based model is used to investigate the sensitivity of the spread rate of exotic S. alterniflora to parameters of long distance dispersal (c, maximum colonial establishment rate) and local colony diffusion (r, intrinsic growth rate) at two tidal marshes, the Eastern Chongming and the Jiuduansha Islands, at the Yangtze River estuary. Both Eastern Chong ming and Jiuduansha Islands are now national natural reserves in China, which were established in 2005. However, the mudflats and salt marshes in the two reserves are now heavily infested with introduced S. alterniflora, which may threaten the estuarine ecosystems and their biodiversity. S. alterniflora was first found in 1995 on Chongming. For rapid sediment accretion in mudflats in the estuary, S. alterniflora was also intentionally introduced to Jiuduansha in 1997 and Chongming in 2001, which has led to a rapid range expansion in the estuary. Our results show that range expansion of species with stratified diffusion is affected by both long-distance dispersal and local colony diffusion, and that there is a critical c*, below which the spread rate is more influenced by long-distance dispersal than by local diffusion. After applying this model to the invasion of S. alterniflora in the Yangtze River estuary, we derive that c = 1.7 × 10-3, c* = 0.126 and c = 4.8 × 10-3 km-2·yr-1, c* = 0.140 km-2·yr-1 at Chongming and Jiuduansha (Shanghai), respectively. Our results suggest that the range spread of S. alterniflora in the Yangtze River estuary is more influenced by long-distance dispersal than local colony diffusion, and that S. alterniflora generates about 1.7 × 10-3 to 4.8 × 10-3 colonies per square kilometers per year. This study provides important information about dispersal dynamics of S. alterniflora that may be useful for finding optimal control strategies. ·展开更多
基金supported by the National Natural Science Foundation of China (22275018)the Project of State Key Laboratory of Explosion Science and Technology (Beijing Institute of Technology)(Grant No.QNKT20-04)。
文摘To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.
基金the financial support from the National Natural Science Foundation of China (52125301 and 52203123)the Fundamental Research Funds for the Central Universitiespartially sponsored by the Double First-Class Construction Funds of Sichuan University。
文摘The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and beyond.Herein,by learning from the pencil-writing process,a facile solid-ink rubbing technology(SIR-tech)is invented to address the above challenge.The solid-ink is exampled by rational combination of liquid metal and graphite particles.By harnessing the synergistic effects between rubbing and adhesion,controllable metallic skin is successfully formed onto metals,woods,ceramics,and plastics without limitation in size and shape.Moreover,outperforming pure liquid-metal coating,the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing.The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well.For applications,the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils.Meanwhile,advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from-196 to 120℃.This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.
基金supported by the National Natural Science Fund of China(Grant No.41572322)Hubei Innovation Group Fund(Grant No.2015CFA024)
文摘This study is the first systematic assessment of the Lower Ordovician microbial carbonates in Songzi,Hubei Province,China.This paper divides the microbial carbonates into two types according to growth patterns,namely nongranular and granular.The nongranular types include stromatolites,thrombolites,dendrolites,leiolites and laminites;the granular types are mainly oncolites and may include a small amount of microbiogenic oolite.According to their geometric features,the stromatolites can be divided into four types:stratiform,wavy,columnar and domal.Additionally,dipyramidal columnar stromatolites are identified for the first time and represent a new type of columnar stromatolite.The thrombolites are divided into three types:speckled,reticulated and banded.The grazing gastropod Ecculiomphalus and traces of bioturbation are observed in the speckled and reticulated thrombolites.This paper considers these two kinds of thrombolites to represent bioturbated thrombolites.These findings not only fill gaps in the field of domestic Ordovician bioturbated thrombolites but also provide new information for the study of thrombolites.Based on the analysis of the sedimentary characteristics of microbialites,the depositional environments of the various types of microbialites are described,and the distribution patterns of their depositional environments are summarized.The relationship between the development of microbialites and the evolution and radiation of metazoans during the Early to Middle Ordovician is discussed.Consistent with the correspondence between the stepwise and rapid radiation of metazoans and the abrupt reduction in the number of microbialites between the late Early Ordovician and the early Middle Ordovician,fossils of benthonic grazing gastropods(Ecculiomphalus)were found in the stromatolites and thrombolite of the study area.It is believed that the gradual reduction in microbialites was related to the rapid increase in the abundance of metazoans.Grazers not only grazed on the microorganisms that formed stromatolites,resulting in a continuous reduction in the number of stromatolites,but also disrupted the growth state of the stromatolites,resulting in the formation of unique bioturbated thrombolites in the study area.Hydrocarbon potential analysis shows that the microbialites in the Nanjinguan Formation represent better source rocks than those in the other formations.
基金supported jointly by the Special Fund of the Institute of Geophysics,China Earthquake Administration(Grant Nos.DQJB20K36,DQJB19B29,and DQJB20B15)the National Natural Science Foundation of China(Grant Nos.41790462 and 41974069).
文摘On May 21,2021,an MS6.4 earthquake occurred in Yangbi,Yunnan province,China,which exhibited typical foreshock-mainshock-aftershock characteristics.To better understand the velocity structure of the focal area and adjacent fault zones,Pg/Sg travel times at 12 seismic stations for the local earthquakes with ML≥1.5 from 2009-2019 and the Yangbi sequence in May of 2021 were used to invert the three-dimensional(3D)structures for both vP and v_(P)/v_(S).The obtained structure extends deeply to 15 km for area(25°N-26.5°N,99.5°E-101°E)at a horizontal resolution of 10×10 km,and the accuracy of the v_(P) velocity was verified using airgun signals excited by the Binchuan Airgun Transmitting Seismic Station(BATSS).The resulting v_(P) and v^(P)/v_(S) images correlate with existing fault zones and the Yangbi sequence,including:(1)The shallow velocity structure at 0 km agrees with local topography,where the Binchuan basin exhibits low-v_(P) and high-v_(P)/v_(S) values.From 3-15 km,v_(P) and v_(P)/v_(S) show variations,and the boundaries are consistent with the main faults(e.g.,the Weixi-Qiaohou-Weishan,Honghe,and Chenghai faults).(2)The largest foreshock(M_(S)5.6),main-shock(MS6.4),and largest aftershock(M_(S)5.2)occurred near the boundaries where both vP and v_(P)/v_(S) have clear contrasts.(3)Small earthquakes are also concentrated in the transition zone between high-and low-vP and v_(P)/v_(S) anomalies,and are biased toward low-v_(P)/v_(S) zones.(4)Boundaries in v_(P) and v_(P)/v_(S) are observed at 20 km west of the Weixi-Qiaohou-Weishan fault,indicating that there may exist one hidden fault.
文摘A M_(S)6.4 earthquake occurred on 21 May 2021 in Yangbi county,Dali prefecture,Yunnan,China,at 21:48 Beijing Time(13:48 UTC).Earthquakes with an M3.0 or higher occurred before and after the main shock.Seismic data analysis is essential for the in-depth investigation of the 2021 Yangbi M_(S)6.4 earthquake sequence and the seismotectonics of northwestern Yunnan.Institute of Geophysics,China Earthquake Administration(CEA),has compiled a dataset of seismological observations from 157 broadband stations located within 500 km of the epicenter,and has made this dataset available to the earthquake science research community.The dataset(total file size:329 GB)consists of event waveforms with a sampling frequency of 100 sps collected from 18 to 28 May 2021,20-Hz and 100-Hz continuous waveforms collected from 12 to 31 May 2021,and seismic instrument response files.To promote data sharing,the dataset also includes the seismic event waveforms from 20 to 22 May 2021 recorded at 50 stations of the ongoing Binchuan Active Source Geophysical Observation Project,for which the data protection period has not expired.Sample waveforms of the main shock are included in the appendix of this article and can be downloaded from the Earthquake Science website.The event and continuous waveforms are available from the Earthquake Science Data Center website(www.esdc.ac.cn)on application.
文摘The relative contribution of long-distance dispersal and local diffusion in the spread of invasive species has been a subject of much debate. Invasion of the intertidal mudflats by Spartina alterniflora is an ideal example of stratified diffusion, involving both long-distance dispersal of seeds and local diffusion due to clonal growth. In conjunction with experimental data on range radius-versus-time curve, a traveling wave equation-based model is used to investigate the sensitivity of the spread rate of exotic S. alterniflora to parameters of long distance dispersal (c, maximum colonial establishment rate) and local colony diffusion (r, intrinsic growth rate) at two tidal marshes, the Eastern Chongming and the Jiuduansha Islands, at the Yangtze River estuary. Both Eastern Chong ming and Jiuduansha Islands are now national natural reserves in China, which were established in 2005. However, the mudflats and salt marshes in the two reserves are now heavily infested with introduced S. alterniflora, which may threaten the estuarine ecosystems and their biodiversity. S. alterniflora was first found in 1995 on Chongming. For rapid sediment accretion in mudflats in the estuary, S. alterniflora was also intentionally introduced to Jiuduansha in 1997 and Chongming in 2001, which has led to a rapid range expansion in the estuary. Our results show that range expansion of species with stratified diffusion is affected by both long-distance dispersal and local colony diffusion, and that there is a critical c*, below which the spread rate is more influenced by long-distance dispersal than by local diffusion. After applying this model to the invasion of S. alterniflora in the Yangtze River estuary, we derive that c = 1.7 × 10-3, c* = 0.126 and c = 4.8 × 10-3 km-2·yr-1, c* = 0.140 km-2·yr-1 at Chongming and Jiuduansha (Shanghai), respectively. Our results suggest that the range spread of S. alterniflora in the Yangtze River estuary is more influenced by long-distance dispersal than local colony diffusion, and that S. alterniflora generates about 1.7 × 10-3 to 4.8 × 10-3 colonies per square kilometers per year. This study provides important information about dispersal dynamics of S. alterniflora that may be useful for finding optimal control strategies. ·
