Earthquakes result from continuous geodynamic processes.A topic of significant interest for the scientific community is to elaborate on the phenomena governing the faulting and fracturing of crustal rocks.Therefore,in...Earthquakes result from continuous geodynamic processes.A topic of significant interest for the scientific community is to elaborate on the phenomena governing the faulting and fracturing of crustal rocks.Therefore,in this study,uniaxial compressive shear failure experiments were conducted on Fangshan marble rock samples with a prefabricated slot to simulate thrust faulting.The center of each marble plate(105 mm × 80 mm × 5 mm) was engraved with a 30-mm long double-sided nonpenetrating slot(depth:2 mm,width:0.5 mm).The deformation and destruction processes of the rock surface were recorded using a high-speed camera.The digital image correlation method was used to calculate the displacement and strain distribution and variation at different loading stages.The accumulative and incremental displacement fields u and v,strain field exand e_(y),and shear strain e_(xy) were analyzed.When the loading level reached its ultimate value,the strain field was concentrated around the prefabricated slot.The concentration reached a maximum at the ends of the prefabricated slot.The magnitude of shear strain reached 0.1.This experiment contributes to our understanding of the dynamic process of active faulting.展开更多
On May 12,2008,an Mw7.9 earthquake occurred in Wenchuan County,Sichuan Province,China.Movement of Yingxiu–Beichuan Fault in the Longmenshan Fault Zone was considered to be the main cause of the earthquake.Earthquakes...On May 12,2008,an Mw7.9 earthquake occurred in Wenchuan County,Sichuan Province,China.Movement of Yingxiu–Beichuan Fault in the Longmenshan Fault Zone was considered to be the main cause of the earthquake.Earthquakes are closely related to fault activities.Therefore,studying the strain distribution and evolution process around active fault zones is important to the understanding of seismic activities.In this study,we conduct laboratory experiments with uniaxial compression applied to marble sheets with intentionally fabricated cracks.The speckle patterns of the rock samples under different loading conditions are recorded in real time by a digital camera.To calculate the deformation fields of the deliberately cracked marble sheets during different stages of the loading processes,the recorded images are processed by the digital image correlation method.The distribution and variation of the displacement and strain are further analyzed in order to understand the strain localization of and observed damage in the experimental fracture zones.Finally,we compare these laboratory results with the GPS-observed coseismic displacements during the 2008 Wenchuan earthquake,to assess the consistency between our laboratory observations and the field observations of the earthquake,but also to suggest how laboratory results can improve thinking about how earthquake patterns do and do not reflect fault patterns.展开更多
The limited lithium resource in earth's crust has stimulated the pursuit of alternative energy storage technologies to lithium-ion battery.Potassium-ion batteries(KIBs)are regarded as a kind of promising candidate...The limited lithium resource in earth's crust has stimulated the pursuit of alternative energy storage technologies to lithium-ion battery.Potassium-ion batteries(KIBs)are regarded as a kind of promising candidate for large-scale energy storage owing to the high abundance and low cost of potassium resources.Nevertheless,further development and wide application of KIBs are still challenged by several obstacles,one of which is their fast capacity deterioration at high rates.A considerable amount of effort has recently been devoted to address this problem by developing advanced carbonaceous anode materials with diverse structures and morphologies.This review presents and highlights how the architecture engineering of carbonaceous anode materials gives rise to high-rate performances for KIBs,and also the beneficial conceptions are consciously extracted from the recent progress.Particularly,basic insights into the recent engineering strategies,structural innovation,and the related advances of carbonaceous anodes for high-rate KIBs are under specific concerns.Based on the achievements attained so far,a perspective on the foregoing,and proposed possible directions,and avenues for designing high-rate anodes,are presented finally.展开更多
Using a sample of 252 R & D teams in Guangzhou, Foshan, Shenzhen, the researcher empirically examines the relationship between knowledge heterogeneity and knowledge innovation performance, the mediating role of kn...Using a sample of 252 R & D teams in Guangzhou, Foshan, Shenzhen, the researcher empirically examines the relationship between knowledge heterogeneity and knowledge innovation performance, the mediating role of knowledge share. Results indicate that knowledge heterogeneity is positively related to knowledge share, the same with knowledge share and knowledge innovation performance. This paper analyzes the results comprehensively and makes recommendations from multiple perspectives including building the knowledge heterogeneous steams, advocating the collaborative spirit, building a knowledge shared platform, improving the organizational structure, and grooming the communication.展开更多
Seismic hazard analysis is gaining increased attention in the present era because of the catastrophic effects of earthquakes.Scientists always have as a goal to develop new techniques that will help forecast earthquak...Seismic hazard analysis is gaining increased attention in the present era because of the catastrophic effects of earthquakes.Scientists always have as a goal to develop new techniques that will help forecast earthquakes before their reoccurrence. In this research,we have performed a shear failure experiment on rock samples with prefabricated cracks to simulate the process of plate movement that forms strike-slip faults. We studied the evolution law of the deformation field to simulate the shear failure experiment, and these results gave us a comprehensive understanding of the elaborate strain distribution law and its formation process with which to identify actual fault zones. We performed uniaxial compression tests on marble slabs with prefabricated double shear cracks to study the distribution and evolution of the deformation field during shear failure. Analysis of the strain field at different loading stages showed that with an increase in the load, the shear strain field initially changed to a disordered-style distribution. Further, the strain field was partially concentrated and finally completely concentrated near the crack and then distributed in the shape of a strip along the crack. We also computed coefficients of variation(CVs) for the physical quantities u, v, and exy, which varied with the load. The CV curves were found to correspond to the different loading stages. We found that at the uniform deformation stage, the CV value was small and changed slowly,whereas at the later nonuniform deformation stage, the CV value increased sharply and changed abruptly. Therefore, the precursor to a rock sample breakdown can be predicted by observing the variation characteristics of CV statistics. The correlation we found between our experimental and theoretical results revealed that our crack evolution and sample deformation results showed good coupling with seismic distribution characteristics near the San Andreas Fault.展开更多
After the World Health Organization(WHO)declared the coronavirus disease 2019(COVID-19)pandemic in March 2020,the implementation of the most effective interventions became a paramount public health priority in the glo...After the World Health Organization(WHO)declared the coronavirus disease 2019(COVID-19)pandemic in March 2020,the implementation of the most effective interventions became a paramount public health priority in the global response to the COVID-19 pandemic,especially before vaccines were available.Several studies have demonstrated that nonpharmaceutical interventions(NPIs),such as social distancing,wearing facemasks,and school closures,can substantially control the transmission of respiratory infections,including severe acute respiratory syndrome,pandemic H1N1 in 2009,and the COVID-19 pandemic.[1–3]However,various respiratory infections have become more prevalent since the COVID-19 pandemic.Since 2021,the incidence of respiratory syncytial virus(RSV)has rapidly increased in numerous countries,including the United States,[4]Australia,[5]England,[6]Italy,[7]Germany,[8]and Switzerland.[9]In December 2022,5 European countries,including France and the United Kingdom。展开更多
Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured fr...Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured from 7:00 to 20:00 in September, October, and November 2013 at a heavily trafficked residential site in Beijing, China, with average concentrations of hydrogen peroxide(H_2O_2) and methyl hydroperoxide(MHP) at 0.55 ppb and 0.063 ppb, respectively. H_2O_2 concentrations were higher in the afternoon and lower in the morning and evening, while MHP concentrations did not exhibit a regular diurnal pattern. Both H_2O_2 and MHP concentrations increased at dusk in most cases. Both peroxides displayed monthly variations with higher concentrations in September. These results suggested that photochemical activity was the main controlling factor on variations of H_2O_2 concentrations during the measurement period. Increasing concentrations of volatile organic compounds emitted by motor vehicles were important contributors to H_2O_2 and MHP enrichment. High levels of H_2O_2 and MHP concentrations which occurred during the measurement period probably resulted from the transport of a polluted air mass with high water vapor content passing over the Bohai Bay, China.展开更多
Avian influenza viruses(AIVs)are naturally preserved in waterfowls and sometimes spill over to infect humans and mammalian animals.The H3 subtype is one of the most prevalent influenza virus subtypes in waterfowls.Sin...Avian influenza viruses(AIVs)are naturally preserved in waterfowls and sometimes spill over to infect humans and mammalian animals.The H3 subtype is one of the most prevalent influenza virus subtypes in waterfowls.Since 2000,H3 subtype AIVs have been continuously isolated from poultry and wild birds in the mainland of China,which implied a dynamic spread in large-scale geography and multiple species.Combinations of H3 with N1–N8 subtypes were reported,among which H3N2 and H3N8 subtypes predominated.展开更多
基金This research was supported by the National Key R&D Program of China(Nos.2018YFC1504203 and SQ2017YFSF040025).
文摘Earthquakes result from continuous geodynamic processes.A topic of significant interest for the scientific community is to elaborate on the phenomena governing the faulting and fracturing of crustal rocks.Therefore,in this study,uniaxial compressive shear failure experiments were conducted on Fangshan marble rock samples with a prefabricated slot to simulate thrust faulting.The center of each marble plate(105 mm × 80 mm × 5 mm) was engraved with a 30-mm long double-sided nonpenetrating slot(depth:2 mm,width:0.5 mm).The deformation and destruction processes of the rock surface were recorded using a high-speed camera.The digital image correlation method was used to calculate the displacement and strain distribution and variation at different loading stages.The accumulative and incremental displacement fields u and v,strain field exand e_(y),and shear strain e_(xy) were analyzed.When the loading level reached its ultimate value,the strain field was concentrated around the prefabricated slot.The concentration reached a maximum at the ends of the prefabricated slot.The magnitude of shear strain reached 0.1.This experiment contributes to our understanding of the dynamic process of active faulting.
文摘On May 12,2008,an Mw7.9 earthquake occurred in Wenchuan County,Sichuan Province,China.Movement of Yingxiu–Beichuan Fault in the Longmenshan Fault Zone was considered to be the main cause of the earthquake.Earthquakes are closely related to fault activities.Therefore,studying the strain distribution and evolution process around active fault zones is important to the understanding of seismic activities.In this study,we conduct laboratory experiments with uniaxial compression applied to marble sheets with intentionally fabricated cracks.The speckle patterns of the rock samples under different loading conditions are recorded in real time by a digital camera.To calculate the deformation fields of the deliberately cracked marble sheets during different stages of the loading processes,the recorded images are processed by the digital image correlation method.The distribution and variation of the displacement and strain are further analyzed in order to understand the strain localization of and observed damage in the experimental fracture zones.Finally,we compare these laboratory results with the GPS-observed coseismic displacements during the 2008 Wenchuan earthquake,to assess the consistency between our laboratory observations and the field observations of the earthquake,but also to suggest how laboratory results can improve thinking about how earthquake patterns do and do not reflect fault patterns.
基金National Natural Science Foundation of China,Grant/Award Numbers:51972121,51972270,51702262Tip-top Scientific and Technical Innovative Youth Talents of Guangdong Special Support Program,Grant/Award Number:2017TQ04C419Key Research and Development Program of Shaanxi Province,Grant/Award Number:2019TSLGY07-03。
文摘The limited lithium resource in earth's crust has stimulated the pursuit of alternative energy storage technologies to lithium-ion battery.Potassium-ion batteries(KIBs)are regarded as a kind of promising candidate for large-scale energy storage owing to the high abundance and low cost of potassium resources.Nevertheless,further development and wide application of KIBs are still challenged by several obstacles,one of which is their fast capacity deterioration at high rates.A considerable amount of effort has recently been devoted to address this problem by developing advanced carbonaceous anode materials with diverse structures and morphologies.This review presents and highlights how the architecture engineering of carbonaceous anode materials gives rise to high-rate performances for KIBs,and also the beneficial conceptions are consciously extracted from the recent progress.Particularly,basic insights into the recent engineering strategies,structural innovation,and the related advances of carbonaceous anodes for high-rate KIBs are under specific concerns.Based on the achievements attained so far,a perspective on the foregoing,and proposed possible directions,and avenues for designing high-rate anodes,are presented finally.
文摘Using a sample of 252 R & D teams in Guangzhou, Foshan, Shenzhen, the researcher empirically examines the relationship between knowledge heterogeneity and knowledge innovation performance, the mediating role of knowledge share. Results indicate that knowledge heterogeneity is positively related to knowledge share, the same with knowledge share and knowledge innovation performance. This paper analyzes the results comprehensively and makes recommendations from multiple perspectives including building the knowledge heterogeneous steams, advocating the collaborative spirit, building a knowledge shared platform, improving the organizational structure, and grooming the communication.
基金Support for this research was provided by the National Key R&D Program of China(grant numbers 2018YFC1504203 and SQ2017YFSF040025)
文摘Seismic hazard analysis is gaining increased attention in the present era because of the catastrophic effects of earthquakes.Scientists always have as a goal to develop new techniques that will help forecast earthquakes before their reoccurrence. In this research,we have performed a shear failure experiment on rock samples with prefabricated cracks to simulate the process of plate movement that forms strike-slip faults. We studied the evolution law of the deformation field to simulate the shear failure experiment, and these results gave us a comprehensive understanding of the elaborate strain distribution law and its formation process with which to identify actual fault zones. We performed uniaxial compression tests on marble slabs with prefabricated double shear cracks to study the distribution and evolution of the deformation field during shear failure. Analysis of the strain field at different loading stages showed that with an increase in the load, the shear strain field initially changed to a disordered-style distribution. Further, the strain field was partially concentrated and finally completely concentrated near the crack and then distributed in the shape of a strip along the crack. We also computed coefficients of variation(CVs) for the physical quantities u, v, and exy, which varied with the load. The CV curves were found to correspond to the different loading stages. We found that at the uniform deformation stage, the CV value was small and changed slowly,whereas at the later nonuniform deformation stage, the CV value increased sharply and changed abruptly. Therefore, the precursor to a rock sample breakdown can be predicted by observing the variation characteristics of CV statistics. The correlation we found between our experimental and theoretical results revealed that our crack evolution and sample deformation results showed good coupling with seismic distribution characteristics near the San Andreas Fault.
基金the National Nature Science Foundation of China(81961128002).
文摘After the World Health Organization(WHO)declared the coronavirus disease 2019(COVID-19)pandemic in March 2020,the implementation of the most effective interventions became a paramount public health priority in the global response to the COVID-19 pandemic,especially before vaccines were available.Several studies have demonstrated that nonpharmaceutical interventions(NPIs),such as social distancing,wearing facemasks,and school closures,can substantially control the transmission of respiratory infections,including severe acute respiratory syndrome,pandemic H1N1 in 2009,and the COVID-19 pandemic.[1–3]However,various respiratory infections have become more prevalent since the COVID-19 pandemic.Since 2021,the incidence of respiratory syncytial virus(RSV)has rapidly increased in numerous countries,including the United States,[4]Australia,[5]England,[6]Italy,[7]Germany,[8]and Switzerland.[9]In December 2022,5 European countries,including France and the United Kingdom。
基金supported by the International Cooperation Project of MOST(No.2012DFG90290)the National Natural Science Foundation of China(No.4225001046)+1 种基金National Department Public Benefit Research Foundation(No.201509014)the Basic Foundation for Public Benefit-Research Academies from Centre Government(No.2010KYYW02)
文摘Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured from 7:00 to 20:00 in September, October, and November 2013 at a heavily trafficked residential site in Beijing, China, with average concentrations of hydrogen peroxide(H_2O_2) and methyl hydroperoxide(MHP) at 0.55 ppb and 0.063 ppb, respectively. H_2O_2 concentrations were higher in the afternoon and lower in the morning and evening, while MHP concentrations did not exhibit a regular diurnal pattern. Both H_2O_2 and MHP concentrations increased at dusk in most cases. Both peroxides displayed monthly variations with higher concentrations in September. These results suggested that photochemical activity was the main controlling factor on variations of H_2O_2 concentrations during the measurement period. Increasing concentrations of volatile organic compounds emitted by motor vehicles were important contributors to H_2O_2 and MHP enrichment. High levels of H_2O_2 and MHP concentrations which occurred during the measurement period probably resulted from the transport of a polluted air mass with high water vapor content passing over the Bohai Bay, China.
基金The National Natural Science Foundation of China(No:81961128002).
文摘Avian influenza viruses(AIVs)are naturally preserved in waterfowls and sometimes spill over to infect humans and mammalian animals.The H3 subtype is one of the most prevalent influenza virus subtypes in waterfowls.Since 2000,H3 subtype AIVs have been continuously isolated from poultry and wild birds in the mainland of China,which implied a dynamic spread in large-scale geography and multiple species.Combinations of H3 with N1–N8 subtypes were reported,among which H3N2 and H3N8 subtypes predominated.
