To date,lithium-ion batteries are becoming increasingly significant in the application of portable devices and electrical vehicles,and revolutionary progress in theoretical research and industrial application has been...To date,lithium-ion batteries are becoming increasingly significant in the application of portable devices and electrical vehicles,and revolutionary progress in theoretical research and industrial application has been achieved.However,the commercial polyolefin separators with unsatisfying electrolytes affinity and poor thermal stability have extremely restricted the further application of lithium-ion batteries,especially in the high-temperature fields.In this work,magnetron sputtering deposition technique is employed to modify the commercial polyimide separator by coating silicon nitride on both sides.Magnetron sputtering deposition modified polyimide(MSD-PI)composite separator shows high thermal stability and ionic conductivity.More importantly,compared with the cells using Celgard separator,the cells with MSD-PI separator exhibit superior electrochemical performance,especially long-term cycle performance under high temperature environment,owing to the high thermal conductivity of surface Si3 N4 particles.Hence,lithium-ion batteries with MSD-PI separator are capable of improving thermal safety and capacity retention,which demonstrates that magnetron sputtering deposition technique could be regarded as a promising strategy to develop advanced organic/inorganic composite separators for high-temperature lithium-ion batteries.展开更多
The May 222021 M_(W)7.4 Madoi,Qinghai,China earthquake presented a rare opportunity to apply the modern unmanned aerial vehicle(UAV)photography method in extreme altitude and weather conditions to image surface ruptur...The May 222021 M_(W)7.4 Madoi,Qinghai,China earthquake presented a rare opportunity to apply the modern unmanned aerial vehicle(UAV)photography method in extreme altitude and weather conditions to image surface ruptures and near-field effects of earthquake-related surface deformations in the remote Tibet.High-resolution aerial photographs were acquired in the days immediately following the mainshock.The complex surface rupture patterns associated with this event were covered comprehensively at 3-6 cm resolution.This effort represents the first time that an earthquake rupture in the interior of the Qinghai-Tibetan Plateau has been fully and systematically captured by such high-resolution imagery,with an unprecedented level of detail,over its entire length.The dataset has proven valuable in documenting subtle and transient rupture features,such as the significant mole-tracks and opening fissures,which were ubiquitous coseismically but degraded during the subsequent summer storm season.Such high-quality imagery also helps to document with high fidelity the fractures of the surface rupture zone(supplements of this paper),the pattern related to how the faults ruptured to the ground surface,and the distribution of off-fault damage.In combination with other ground-based mapping efforts,the data will be analyzed in the following months to better understand the mechanics of earthquake rupture related to the fault zone rheology,rupture dynamics,and frictional properties along with the fault interface.展开更多
The fire hazard of lithium-ion batteries(LIBs)modules is extremely serious due to their high capacity.Moreover,once a battery catches fire,it can easily result in a fire of the entire LIBs modules.In this work,a sandw...The fire hazard of lithium-ion batteries(LIBs)modules is extremely serious due to their high capacity.Moreover,once a battery catches fire,it can easily result in a fire of the entire LIBs modules.In this work,a sandwich structure composite thermal insulation(STI)board(copper//silica dioxide aerogel//copper)with the advantages of low thermal conductivity(0.031 W m-1K-1),low surface radiation emissivity(0.1)and good thermal convection inhibition effect has been designed.The thermal runaway(TR)occurrence time of adjacent LIBs increases from 1384 s to more than 6 h+due to the protection of STI board.No TR propagation occurs within LIBs modules with protect of a STI board when a battery catches fire.The ultra-strong-heat-shielding mechanism of STI board has been revealed.The TR propagation of LIBs modules has been insulated effectively by STI board through reducing the heat transfer of convection,conduction and radiation.The air flow rate between the heater and LIBs and radiant heat absorbed by LIBs decrease by 63.5%and 35.1%with protection of STI board,respectively.A high temperature difference inside the STI board is also formed.This work provides direction for the designing of safe thermal insulation board for LIBs modules.展开更多
In this work,we have successfully prepared a novel separator modified with N,S co-doped carbon framework(named NSPCF)with confined CoS_(2) nanoparticles and rooted carbon nanotubes material(named NSPCF@CoS_(2))to appl...In this work,we have successfully prepared a novel separator modified with N,S co-doped carbon framework(named NSPCF)with confined CoS_(2) nanoparticles and rooted carbon nanotubes material(named NSPCF@CoS_(2))to apply for high-performance Lithium-Sulfur batteries(Li-S batteries).Robust carbon structure with large specific surface can act as a physical barrier and possess physical adsorption effect on lithium polysulfides(LiPSs).In addition,highly-conductive carbon can improve integral conductivity,leading to the fast charge transport and reaction kinetics.Also,doping heteroatoms could form more active sites to adsorb LiPSs strongly so that modified separator could inhibit the shuttle effect effectively.Moreover,the presence of CoS_(2) further enhances the ability of modified separator to trap LiPSs owing to the Lewis acid-base action.As a result,the NSPCF@CoS_(2)@C-150 battery can deliver initial discharge capacities of 863.0,776.2,649.1 and 489.4 mAh g^(-1) at 0.1,0.5,1 and 2C with a high sulfur loading of 2.04 mg cm^(-2),respectively.Notably,when turning the current density back to 0.1 C,its discharge capacity can recover to 1008.7 mAh g^(-1).In addition,the modified separators exhibit outstanding capacities to restrain the growth of lithium dendrites.It is noteworthy that the flame retardant performances of Li-S batteries are improved dramatically owing to the novel structures of modified separators.This rationally designed separator endows Li-S batteries with higher safety and excellent electrochemical performances,providing a feasible strategy for practical application of Li-S batteries.展开更多
1 Introduction Endoscopy plays a crucial role in the diagnoses and treatment of gastrointestinal(GI)diseases[1],as it helps to identify abnormalities,classify lesion,and determine treatment methods.During GI endoscopi...1 Introduction Endoscopy plays a crucial role in the diagnoses and treatment of gastrointestinal(GI)diseases[1],as it helps to identify abnormalities,classify lesion,and determine treatment methods.During GI endoscopic examinations,physicians may encounter practical hindrances,i.e.,fatigue,stress,or limited experience,which can lead to erroneous results.Artificial intelligence(AI)-assisted GI endoscopy technology has emerged to address these limitations[2].展开更多
The high energy density of lithium metal batteries(LMBs)has attracted widespread attention,which is expected to improve the endurance mileage of electric vehicles comparable to fossil fuel-powered vehicles.At present,...The high energy density of lithium metal batteries(LMBs)has attracted widespread attention,which is expected to improve the endurance mileage of electric vehicles comparable to fossil fuel-powered vehicles.At present,the main research is focused on developing advanced materials and revealing the indepth electrochemical mechanism of LMBs,while there is a significant lagging behind of attention to the safety evaluation.This review aims to emphasize the fire safety challenges faced by LMBs and summarize advanced strategies for improving intrinsic safety.Firstly,the basic chemical composition and working principle of LMBs were introduced compared with lithium-ion batteries.Moreover,we reviewed the thermal runaway problem of LMBs from the aspects of material activity,interfacial stability triggering conditions,thermal runaway behavior and mechanism,the special thermal runaway characteristics,and new safety challenges of Li-S,Li-O_(2),and the solid-state LMBs were discussed in detail.Based on the analysis of the thermal runaway mechanism,we summarized the advanced strategies,including electrolyte design,interphase film construction,separator,and anode design for improving the intrinsic safety of LMBs.Finally,we proposed the fire safety challenge at the battery level and emphasized the necessity of designing safe materials based on the thermal runaway mechanism.Blocking the thermal coupling reaction and conducting multi-strategy collaborative optimization is the key point to restrain thermal runaway.展开更多
Large-scale detailed mapping plays a key role in revealing the rupture characteristics and mechanisms of strong earthquakes.Relatively few studies have been performed on the surface ruptures of large earthquakes in ce...Large-scale detailed mapping plays a key role in revealing the rupture characteristics and mechanisms of strong earthquakes.Relatively few studies have been performed on the surface ruptures of large earthquakes in central and western Tibet due to its remote nature and high elevation.Based on high-resolution unmanned aerial vehicle(UAV)photography,we mapped the coseismic surface rupture of the 2014 Yutian M_s7.3 earthquake.Along the western Altyn Tagh fault system,the earthquake produced~37 km of surface rupture along the South Xor Kol fault(southern section S1),Xor Kol fault(central section S2)and Ashikule fault(northern section S3).Section S1 has a 16-km-long surface rupture with an average sinistral offset of 52±25 cm and a maximum offset of~90 cm,while section S3 has a 14.2-km-long surface rupture with an average sinistral offset of 36±21 cm and a maximum offset of~84 cm.A compilation of 5308 cracks yields an average crack width along the southern section of 85±71 cm and a maximum width of~700 cm;the average width along the central section is 39±21 cm,and the maximum width is 243 cm;and the average width along the northern section is 61±44 cm with a maximum of~340 cm.In addition,the average cumulative opening across rupture zone is 3.4±2.9 m along the southern section,with a maximum of~17 m;4.3±3.6 m along the central section,with a maximum of~13 m;and 1.7±1.6 m along the northern section,with a maximum of~6 m.Evidently,the average crack width and cumulative opening decrease towards bends and steps along the fault.A global synthesis of surface rupture distributions corresponding to strike-slip earthquakes indicates that the rupture zone is wider near the complex parts of fault geometries(such as bends,steps and fault bifurcations)than along straight sections,suggesting that the fault geometry has an obvious control on the surface rupture width.The widespread cracks at the intersection between the Xor Kol and South Xor Kol faults may indicate that an extensional regime is more likely to produce distributed offfault deformation,which provides an observational constraint for the numerical simulation of dynamic rupture on a fault.In addition to coseismic surface rupture,the Yutian earthquake also produced a large number of gravity-driven slides on alluvial fans with gentle slopes.The friction efficiency of the water-bearing salt layer beneath fans could decrease the sliding threshold and trigger instability under surface shaking.These distributed deformations and gravity-driven slides reflect the coupling between the rupture propagation and fault geometry and indicate that the rupture may have propagated in two directions along the Ashikule fault after passing through a step.Therefore,the investigation of coseismic surface rupture provides important observational constraints on the dynamic rupture process.展开更多
Owing to unprecedented merits such as high theoretical capacity,superior energy density and low cost,lithium-sulfur batteries(LSBs)show a bright future both in scientific and industrial areas.Whereas,the inherent issu...Owing to unprecedented merits such as high theoretical capacity,superior energy density and low cost,lithium-sulfur batteries(LSBs)show a bright future both in scientific and industrial areas.Whereas,the inherent issues,including highly insulating character,undesired shuttle behavior and lithium dendrites growth,are seriously impeding its practical usage.Here,a metal-organic-frameworks(MOFs)derived N,S co-doped carbon nanotube hollow architecture confining with CoS_(2) nanoparticles(CoS_(2)/NSCNHF)modified separator is designed to surmount these obstacles.Compared with Celgard separator,this designed separator shows obviously enhanced flame retardancy,giving 73.1%and 53.0%reductions in peak heat release rate and total heat release,separately.Concretely,its hollow structure,conductive feature,electrocatalytic activity and Lewis acid-base interaction enable the efficient inhibition on shuttle behavior as well as boost in polysulfides conversion kinetics.The cell with modified separator delivers a high discharge capacity of 1,284.5 mAh·g^(−1).After running for 100 cycles,a discharge capacity of 661.3 mAh·g^(−1) is remained.Markedly,the suppression on lithium dendrites growth is also observed,manifesting the enhanced battery safety.Overall,this work may shed light on the effective usage of MOFs-derived hierarchical composite in achieving LSBs with high electrochemical performance as well as safety.展开更多
The Altyn Tagh fault is one of the few great active strike-slip faults in the world. The recurrence characteristics of paleoearthquakes on this fault are still poorly understood due to the lack of paleoseismic records...The Altyn Tagh fault is one of the few great active strike-slip faults in the world. The recurrence characteristics of paleoearthquakes on this fault are still poorly understood due to the lack of paleoseismic records recorded in high-resolution strata. We document a paleoseismic record in a pull-apart basin along the Wuzunxiaoer section of the central Altyn Tagh fault.The high-resolution strata recorded abundant seismic deformations and their sedimentary responses. Four earthquakes are identified based on event evidence in the form of open fissures, thickened strata, angular unconformities, and folds. The occurrence times of the four events were constrained using radiocarbon dating. Event W1 occurred at AD1220–1773, events W2 and W3 occurred between 407 and 215 BC, and event W4 occurred slightly earlier at 1608–1462 BC, indicating clustered recurrence characteristics. A comparison of the earthquake records along the Wuzunxiaoer section with other records along the Xorkoli section suggests that both sections ruptured during the most recent event.展开更多
Knowledge distillation aims to distill knowledge from teacher networks to train student networks.Distilling intermediate features has attracted much attention in recent years as it can beflexibly applied in variousfiel...Knowledge distillation aims to distill knowledge from teacher networks to train student networks.Distilling intermediate features has attracted much attention in recent years as it can beflexibly applied in variousfields such as image classification,object detection and semantic segmentation.A critical obstacle of feature-based knowledge distillation is the dimension gap between the intermediate features of teacher and student,and plenty of methods have been proposed to resolve this problem.However,these works usually implement feature uniformization in an unsupervised way,lacking guidance to help the student network learn meaningful mapping functions in the uniformization process.Moreover,the dimension uniformization process of the student and teacher network is usually not equivalent as the mapping functions are different.To this end,some factors of the feature are discarded during parametric feature alignment,or some factors are blended in some non-parametric operations.In this paper,we propose a novel semantic-aware knowledge distillation scheme to solve these problems.We build a standalone feature-based classification branch to extract semantic-aware knowledge for better guiding the learning process of the student network.In addition,to avoid the inequivalence of feature uniformization between teacher and student,we design a novel parameter-free self-attention operation that can convert features of different dimensions into vectors of the same length.Experimental results show that the proposed knowledge distillation scheme outperforms existing feature-based distillation methods on the widely used CIFAR-100 and CINIC-10 datasets.展开更多
基金supported by the National Natural Science Foundation of China(51704269 and 51573173)Fundamental Research Funds for the Central Universities(WK2320000037)。
文摘To date,lithium-ion batteries are becoming increasingly significant in the application of portable devices and electrical vehicles,and revolutionary progress in theoretical research and industrial application has been achieved.However,the commercial polyolefin separators with unsatisfying electrolytes affinity and poor thermal stability have extremely restricted the further application of lithium-ion batteries,especially in the high-temperature fields.In this work,magnetron sputtering deposition technique is employed to modify the commercial polyimide separator by coating silicon nitride on both sides.Magnetron sputtering deposition modified polyimide(MSD-PI)composite separator shows high thermal stability and ionic conductivity.More importantly,compared with the cells using Celgard separator,the cells with MSD-PI separator exhibit superior electrochemical performance,especially long-term cycle performance under high temperature environment,owing to the high thermal conductivity of surface Si3 N4 particles.Hence,lithium-ion batteries with MSD-PI separator are capable of improving thermal safety and capacity retention,which demonstrates that magnetron sputtering deposition technique could be regarded as a promising strategy to develop advanced organic/inorganic composite separators for high-temperature lithium-ion batteries.
基金This work was supported by the National Natural Science Foundation of China(U1839203,42011540385)the National Key Laboratory of Earthquake Dynamics(LED2020B03,IGCEA1812)the Science and Technology Projects of Qinghai Province(2020-ZJ-752).
文摘The May 222021 M_(W)7.4 Madoi,Qinghai,China earthquake presented a rare opportunity to apply the modern unmanned aerial vehicle(UAV)photography method in extreme altitude and weather conditions to image surface ruptures and near-field effects of earthquake-related surface deformations in the remote Tibet.High-resolution aerial photographs were acquired in the days immediately following the mainshock.The complex surface rupture patterns associated with this event were covered comprehensively at 3-6 cm resolution.This effort represents the first time that an earthquake rupture in the interior of the Qinghai-Tibetan Plateau has been fully and systematically captured by such high-resolution imagery,with an unprecedented level of detail,over its entire length.The dataset has proven valuable in documenting subtle and transient rupture features,such as the significant mole-tracks and opening fissures,which were ubiquitous coseismically but degraded during the subsequent summer storm season.Such high-quality imagery also helps to document with high fidelity the fractures of the surface rupture zone(supplements of this paper),the pattern related to how the faults ruptured to the ground surface,and the distribution of off-fault damage.In combination with other ground-based mapping efforts,the data will be analyzed in the following months to better understand the mechanics of earthquake rupture related to the fault zone rheology,rupture dynamics,and frictional properties along with the fault interface.
基金the support from the National Science and Technology Major Project(J2019-VIII-00100171)the National Natural Science Foundation of China(51991352,51973203)+3 种基金the China Postdoctoral Special Funding(2019TQ0309)the China Postdoctoral Science Foundation(2020M671904)the Fundamental Research Funds for the Central Universities(WK2320000057)the University of Synergy Innovation Program of Anhui Province(GXXT-2020-079)。
文摘The fire hazard of lithium-ion batteries(LIBs)modules is extremely serious due to their high capacity.Moreover,once a battery catches fire,it can easily result in a fire of the entire LIBs modules.In this work,a sandwich structure composite thermal insulation(STI)board(copper//silica dioxide aerogel//copper)with the advantages of low thermal conductivity(0.031 W m-1K-1),low surface radiation emissivity(0.1)and good thermal convection inhibition effect has been designed.The thermal runaway(TR)occurrence time of adjacent LIBs increases from 1384 s to more than 6 h+due to the protection of STI board.No TR propagation occurs within LIBs modules with protect of a STI board when a battery catches fire.The ultra-strong-heat-shielding mechanism of STI board has been revealed.The TR propagation of LIBs modules has been insulated effectively by STI board through reducing the heat transfer of convection,conduction and radiation.The air flow rate between the heater and LIBs and radiant heat absorbed by LIBs decrease by 63.5%and 35.1%with protection of STI board,respectively.A high temperature difference inside the STI board is also formed.This work provides direction for the designing of safe thermal insulation board for LIBs modules.
基金supported by the National Natural Science Foundation of China(51704269)the Fundamental Research Funds for the Central Universities(WK2320000041).
文摘In this work,we have successfully prepared a novel separator modified with N,S co-doped carbon framework(named NSPCF)with confined CoS_(2) nanoparticles and rooted carbon nanotubes material(named NSPCF@CoS_(2))to apply for high-performance Lithium-Sulfur batteries(Li-S batteries).Robust carbon structure with large specific surface can act as a physical barrier and possess physical adsorption effect on lithium polysulfides(LiPSs).In addition,highly-conductive carbon can improve integral conductivity,leading to the fast charge transport and reaction kinetics.Also,doping heteroatoms could form more active sites to adsorb LiPSs strongly so that modified separator could inhibit the shuttle effect effectively.Moreover,the presence of CoS_(2) further enhances the ability of modified separator to trap LiPSs owing to the Lewis acid-base action.As a result,the NSPCF@CoS_(2)@C-150 battery can deliver initial discharge capacities of 863.0,776.2,649.1 and 489.4 mAh g^(-1) at 0.1,0.5,1 and 2C with a high sulfur loading of 2.04 mg cm^(-2),respectively.Notably,when turning the current density back to 0.1 C,its discharge capacity can recover to 1008.7 mAh g^(-1).In addition,the modified separators exhibit outstanding capacities to restrain the growth of lithium dendrites.It is noteworthy that the flame retardant performances of Li-S batteries are improved dramatically owing to the novel structures of modified separators.This rationally designed separator endows Li-S batteries with higher safety and excellent electrochemical performances,providing a feasible strategy for practical application of Li-S batteries.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.62272468,62003256,62027813,U1801265,62293543,62322605,62036005,62202015,and U21B2048)the Key-Area Research and Development Program of Shaanxi Province(2023-ZDLSF-41)+2 种基金the Anhui Medical University(2022xkj105,2023cy021)the Anhui Provincial Key R&D Program(2023s07020001)the University Synergy Innovation Program of Anhui Province(GXXT-2022-052).
文摘1 Introduction Endoscopy plays a crucial role in the diagnoses and treatment of gastrointestinal(GI)diseases[1],as it helps to identify abnormalities,classify lesion,and determine treatment methods.During GI endoscopic examinations,physicians may encounter practical hindrances,i.e.,fatigue,stress,or limited experience,which can lead to erroneous results.Artificial intelligence(AI)-assisted GI endoscopy technology has emerged to address these limitations[2].
基金supported by the National Natural Science Foundation of China(No.52204248)the Taishan Scholars Program of Shandong Province(tsqn202408191)。
文摘The high energy density of lithium metal batteries(LMBs)has attracted widespread attention,which is expected to improve the endurance mileage of electric vehicles comparable to fossil fuel-powered vehicles.At present,the main research is focused on developing advanced materials and revealing the indepth electrochemical mechanism of LMBs,while there is a significant lagging behind of attention to the safety evaluation.This review aims to emphasize the fire safety challenges faced by LMBs and summarize advanced strategies for improving intrinsic safety.Firstly,the basic chemical composition and working principle of LMBs were introduced compared with lithium-ion batteries.Moreover,we reviewed the thermal runaway problem of LMBs from the aspects of material activity,interfacial stability triggering conditions,thermal runaway behavior and mechanism,the special thermal runaway characteristics,and new safety challenges of Li-S,Li-O_(2),and the solid-state LMBs were discussed in detail.Based on the analysis of the thermal runaway mechanism,we summarized the advanced strategies,including electrolyte design,interphase film construction,separator,and anode design for improving the intrinsic safety of LMBs.Finally,we proposed the fire safety challenge at the battery level and emphasized the necessity of designing safe materials based on the thermal runaway mechanism.Blocking the thermal coupling reaction and conducting multi-strategy collaborative optimization is the key point to restrain thermal runaway.
基金supported by the National Natural Science Foundation of China(Grant Nos.41902216,U1839203)Central Public-Interest Scientific Institution Basal Research Fund(Grant Nos.IGCEA1814,IGCEA1812)。
文摘Large-scale detailed mapping plays a key role in revealing the rupture characteristics and mechanisms of strong earthquakes.Relatively few studies have been performed on the surface ruptures of large earthquakes in central and western Tibet due to its remote nature and high elevation.Based on high-resolution unmanned aerial vehicle(UAV)photography,we mapped the coseismic surface rupture of the 2014 Yutian M_s7.3 earthquake.Along the western Altyn Tagh fault system,the earthquake produced~37 km of surface rupture along the South Xor Kol fault(southern section S1),Xor Kol fault(central section S2)and Ashikule fault(northern section S3).Section S1 has a 16-km-long surface rupture with an average sinistral offset of 52±25 cm and a maximum offset of~90 cm,while section S3 has a 14.2-km-long surface rupture with an average sinistral offset of 36±21 cm and a maximum offset of~84 cm.A compilation of 5308 cracks yields an average crack width along the southern section of 85±71 cm and a maximum width of~700 cm;the average width along the central section is 39±21 cm,and the maximum width is 243 cm;and the average width along the northern section is 61±44 cm with a maximum of~340 cm.In addition,the average cumulative opening across rupture zone is 3.4±2.9 m along the southern section,with a maximum of~17 m;4.3±3.6 m along the central section,with a maximum of~13 m;and 1.7±1.6 m along the northern section,with a maximum of~6 m.Evidently,the average crack width and cumulative opening decrease towards bends and steps along the fault.A global synthesis of surface rupture distributions corresponding to strike-slip earthquakes indicates that the rupture zone is wider near the complex parts of fault geometries(such as bends,steps and fault bifurcations)than along straight sections,suggesting that the fault geometry has an obvious control on the surface rupture width.The widespread cracks at the intersection between the Xor Kol and South Xor Kol faults may indicate that an extensional regime is more likely to produce distributed offfault deformation,which provides an observational constraint for the numerical simulation of dynamic rupture on a fault.In addition to coseismic surface rupture,the Yutian earthquake also produced a large number of gravity-driven slides on alluvial fans with gentle slopes.The friction efficiency of the water-bearing salt layer beneath fans could decrease the sliding threshold and trigger instability under surface shaking.These distributed deformations and gravity-driven slides reflect the coupling between the rupture propagation and fault geometry and indicate that the rupture may have propagated in two directions along the Ashikule fault after passing through a step.Therefore,the investigation of coseismic surface rupture provides important observational constraints on the dynamic rupture process.
基金The work was financially supported by the National Natural Science Foundation of China(No.51704269)Fundamental Research Funds for the Central Universities(No.WK2320000047)the Fundamental Research Funds for the Central Universities(No.WK2320000039).
文摘Owing to unprecedented merits such as high theoretical capacity,superior energy density and low cost,lithium-sulfur batteries(LSBs)show a bright future both in scientific and industrial areas.Whereas,the inherent issues,including highly insulating character,undesired shuttle behavior and lithium dendrites growth,are seriously impeding its practical usage.Here,a metal-organic-frameworks(MOFs)derived N,S co-doped carbon nanotube hollow architecture confining with CoS_(2) nanoparticles(CoS_(2)/NSCNHF)modified separator is designed to surmount these obstacles.Compared with Celgard separator,this designed separator shows obviously enhanced flame retardancy,giving 73.1%and 53.0%reductions in peak heat release rate and total heat release,separately.Concretely,its hollow structure,conductive feature,electrocatalytic activity and Lewis acid-base interaction enable the efficient inhibition on shuttle behavior as well as boost in polysulfides conversion kinetics.The cell with modified separator delivers a high discharge capacity of 1,284.5 mAh·g^(−1).After running for 100 cycles,a discharge capacity of 661.3 mAh·g^(−1) is remained.Markedly,the suppression on lithium dendrites growth is also observed,manifesting the enhanced battery safety.Overall,this work may shed light on the effective usage of MOFs-derived hierarchical composite in achieving LSBs with high electrochemical performance as well as safety.
基金supported by National Natural Science Foundation of China (Grant Nos. U1839203, 41761144065, 41802228)Central Public-Interest Scientific Institution Basal Research Fund (Grant No. IGCEA1814)State Key Laboratory of Earthquake Dynamics of China (Grant No. LED2017A01)
文摘The Altyn Tagh fault is one of the few great active strike-slip faults in the world. The recurrence characteristics of paleoearthquakes on this fault are still poorly understood due to the lack of paleoseismic records recorded in high-resolution strata. We document a paleoseismic record in a pull-apart basin along the Wuzunxiaoer section of the central Altyn Tagh fault.The high-resolution strata recorded abundant seismic deformations and their sedimentary responses. Four earthquakes are identified based on event evidence in the form of open fissures, thickened strata, angular unconformities, and folds. The occurrence times of the four events were constrained using radiocarbon dating. Event W1 occurred at AD1220–1773, events W2 and W3 occurred between 407 and 215 BC, and event W4 occurred slightly earlier at 1608–1462 BC, indicating clustered recurrence characteristics. A comparison of the earthquake records along the Wuzunxiaoer section with other records along the Xorkoli section suggests that both sections ruptured during the most recent event.
基金supported in part by Key-Area Research and Development Program of Guangdong Province(Grant No.2021B0101200001)the National Natural Science Foundation of China(Grant No.62293543)+1 种基金the National Natural Science Foundation of China(Grant No.U21B2048)the Open Research Projects of Zhejiang Lab(Grant No.2019KD0AD01/010).
文摘Knowledge distillation aims to distill knowledge from teacher networks to train student networks.Distilling intermediate features has attracted much attention in recent years as it can beflexibly applied in variousfields such as image classification,object detection and semantic segmentation.A critical obstacle of feature-based knowledge distillation is the dimension gap between the intermediate features of teacher and student,and plenty of methods have been proposed to resolve this problem.However,these works usually implement feature uniformization in an unsupervised way,lacking guidance to help the student network learn meaningful mapping functions in the uniformization process.Moreover,the dimension uniformization process of the student and teacher network is usually not equivalent as the mapping functions are different.To this end,some factors of the feature are discarded during parametric feature alignment,or some factors are blended in some non-parametric operations.In this paper,we propose a novel semantic-aware knowledge distillation scheme to solve these problems.We build a standalone feature-based classification branch to extract semantic-aware knowledge for better guiding the learning process of the student network.In addition,to avoid the inequivalence of feature uniformization between teacher and student,we design a novel parameter-free self-attention operation that can convert features of different dimensions into vectors of the same length.Experimental results show that the proposed knowledge distillation scheme outperforms existing feature-based distillation methods on the widely used CIFAR-100 and CINIC-10 datasets.
