In the quasi-free electron model,the Fermi surface spreads into a sphere in the Brillouin zone,i.e.,the Fermi sphere.The Fermi sphere exists widely in metal systems,no matter whether the crystal is in a body-center cu...In the quasi-free electron model,the Fermi surface spreads into a sphere in the Brillouin zone,i.e.,the Fermi sphere.The Fermi sphere exists widely in metal systems,no matter whether the crystal is in a body-center cubic,face-center cubic,or hexagonal close-packed lattice.Here,we report a class of compounds stabilized at high pressure with Rubik’s cubic Fermi surface.展开更多
To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavio...To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavior,including 5%state of charge(SOC)with small current overcharge and resting until the temperature equilibrium under adiabatic conditions.The intrinsic thermal response and the self-excitation behaviour are analysed through temperature and voltage changes during the step overcharge period.Experimental results show that the deintercalated state of the cathode is highly correlated to self-heating parasitic reactions.Before reaching the upper limit of Negative/Positive(N/P)ratio,the temperature changes little,the heat generation is significantly induced by the reversible heat(endothermic)and ohmic heat,which could balance each other.Following that the lithium metal is gradually deposited on the surface of the anode and reacts with electrolyte upon overcharge,inducing selfheating side reaction.However,this spontaneous thermal reaction could be“self-extinguished”.When the lithium in cathode is completely deintercalated,the boundary point of overcharge is about 4.7 V(~148%SOC,>40℃),and from this point,the self-heating behaviour could be continuously triggered until thermal runaway(TR)without additional overcharge.The whole static and spontaneous process lasts for 115 h and the side reaction heat is beyond 320,000 J.The continuous self-excitation behavior inside the battery is attributed to the interaction between the highly oxidized cathode and the solvent,which leads to the dissolution of metal ions.The dissolved metal ions destroy the SEI(solid electrolyte interphase)film on the surface of the deposited Li of anode,which induces the thermal reaction between lithium metal and the solvent.The interaction between cathode,the deposited Li of anode,and solvent promotes the temperature of the battery to rise slowly.When the temperature of the battery reaches more than 60℃,the reaction between lithium metal and solvent is accelerated.After the temperature rises rapidly to the melting point of the separator,it triggers the thermal runaway of the battery due to the short circuit of the battery.展开更多
This paper describes a micro-grid system and its monitoring system. This micro-grid system consists of generation systems, consumer electrical equipments, auxiliary equipments and the monitoring system. All the equipm...This paper describes a micro-grid system and its monitoring system. This micro-grid system consists of generation systems, consumer electrical equipments, auxiliary equipments and the monitoring system. All the equipments have 485 communication interfaces. In order to monitor and manage this micro-grid system, we built a monitoring system, which contains modular instrument system and industrial personal computer. In order to keep real time, we adopt some measures in software and hardware. We adopt LABVIEW and its program modules in software and adopt modular instrument system in hardware. Supporting by the software and hardware, the micro-grid system can be safe and stable.展开更多
A sub-Nyquist radar receiver based on photonics-assisted compressed sensing is proposed.Cascaded dictionaries are applied to extract the delay and the Doppler frequency of the echo signals,which do not need to accumul...A sub-Nyquist radar receiver based on photonics-assisted compressed sensing is proposed.Cascaded dictionaries are applied to extract the delay and the Doppler frequency of the echo signals,which do not need to accumulate multiple echo periods and can achieve better Doppler accuracy.An experiment is performed.Radar echoes with different delays and Doppler frequencies are undersampled and successfully reconstructed to obtain the delay and Doppler information of the targets.Experimental results show that the average reconstruction error of the Doppler frequency is 5.33 kHz using an 8-μs radar signal under the compression ratio of 5.The proposed method provides a promising solution for the sub-Nyquist radar receiver.展开更多
Elasto-capillarity phenomena are prevalent in various industrial fields such as mechanical engineering,material science,aerospace,soft robotics,and biomedicine.In this study,two typical peeling processes of slender be...Elasto-capillarity phenomena are prevalent in various industrial fields such as mechanical engineering,material science,aerospace,soft robotics,and biomedicine.In this study,two typical peeling processes of slender beams driven by the parallel magnetic field are investigated based on experimental and theoretical analysis.The first is the adhesion of two parallel beams,and the second is the self-folding of a long beam.In these two cases,the energy variation method on the elastica is used,and then,the governing equations and transversality boundary conditions are derived.It is shown that the analytical solutions are in excellent agreement with the experimental data.The effects of magnetic induction intensity,distance,and surface tension on the deflection curve and peeling length of the elastica are fully discussed.The results are instrumental in accurately regulating elasto-capillarity in structures and provide insights for the engineering design of programmable microstructures on surfaces,microsensors,and bionic robots.展开更多
Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars wi...Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.展开更多
To satisfy the property requirements for biodegradable medical implants,Zn alloyed with low levels of Mg(≤0.8 wt%)has attracted increased research interest.In the present study,deformation twinning was observed in te...To satisfy the property requirements for biodegradable medical implants,Zn alloyed with low levels of Mg(≤0.8 wt%)has attracted increased research interest.In the present study,deformation twinning was observed in tensile tests and twinning appears to have an adverse impact on ductility.The profuse twinning in the as-cast Zn-Mg alloys accelerated crack growth in tension due to twinning impingement which caused local stress concentrations and initiates cracking.As-rolled Zn-Mg alloys have better ductility than their as-cast counterparts due to the inhibition of twinning by the refined Mg2Zn11 intermetallic phase and the finer grain size.展开更多
Loss of function of large tissues is an urgent clinical problem. Although the artificial microfluidic network fabricated in large tis- sue-engineered constructs has great promise, it is still difficult to develop an e...Loss of function of large tissues is an urgent clinical problem. Although the artificial microfluidic network fabricated in large tis- sue-engineered constructs has great promise, it is still difficult to develop an efficient vessel-like design to meet the requirements of the biomimetic vascular network for tissue engineering applications. In this study, we used a facile approach to fabricate a branched and multi-level vessel-like network in a large muscle scaffolds by combining stereolithography （SL） technology and enzymatic crosslinking mechanism. The morphology of microchannel cross-sections was characterized using micro-computed tomography. The square cross-sections were gradually changed to a seamless circular microfluidic network, which is similar to the natural blood vessel. In the different micro-channels, the velocity greatly affected the attachment and spread of Human Umbilical Vein Endothelial Cell （HUVEC）-Green Fluorescent Protein （GFP）. Our study demonstrated that the branched and multi-level microchannel network simulates biomimetic microenvironments to promote endothelialization. The gelatin scaffolds in the circular vessel-like networks will likely support myoblast and surrounding tissue for clinical use.展开更多
A heterogeneous lamella(HL)design strategy was applied to manipulate mechanical properties of a new cost-effective Fe_(35)Ni_(35)Cr_(25)Mo_(5)compositionally complicated alloy(CCA).The HL structure was produced by sin...A heterogeneous lamella(HL)design strategy was applied to manipulate mechanical properties of a new cost-effective Fe_(35)Ni_(35)Cr_(25)Mo_(5)compositionally complicated alloy(CCA).The HL structure was produced by single-step heat treatment(800℃for 1 h)after cold rolling.This HL structure consists of alternative lamellae regions of coarse-grained FCC matrix(5-20μm),and regions containing ultra-fine grains or subgrains(200-500 nm)together with nanoprecipitates(20-500 nm)and annealing twins.As compared with other cost-effective CCAs,the 800℃annealed sample with HL structure demonstrated a comparable tensile property,with yield strength over 1.0 GPa and total elongation of~13%.Formation of the annealing twins and nanoprecipitates decorated HL structure was a result of the concurrent partial recrystallization and precipitation ofσphase at the shear bands with a high density of lattice defects(e.g.high-density dislocation walls and deformation twins).The latter restricted the growth of recrystallized grains,leading to the formation of ultrafine subgrains within the HL structure.The high yield strength resulted from the multistage hetero-deformation induced(HDI)strengthening and precipitation strengthening associated with heterogeneous lamella structures containing nanoprecipitates.The ductility was originated from the coexistence of multiple deformation mechanisms,which started with dislocation slip and formation of stacking faults at the initial stage,followed by nano-twinning at the higher strain level.This HL design strategy,comprising composition and thermomechanical process designs,and the resultant microstructure tuning,open a broader window for the development of cost-effective CCAs with enhanced performance.展开更多
This work investigates the strain rate dependence of dynamic recrystallization behaviour of high-purity zinc in room temperature compression under strain rates of 10^(-4)s^(-1),10-2s^(-1)and 0.5 s^(-1).Results from el...This work investigates the strain rate dependence of dynamic recrystallization behaviour of high-purity zinc in room temperature compression under strain rates of 10^(-4)s^(-1),10-2s^(-1)and 0.5 s^(-1).Results from electron backscatter diffraction provide insight into the deformation and dynamic recrystallization mechanisms operative.Continuous dynamic recrystallization,twin-induced dynamic recrystallization,and discontinuous dynamic recrystallization are all active under compressive deformation at room temperature.Due to the high stacking fault energy of Zn,continuous dynamic recrystallization is the dominant mechanism while discontinuous dynamic recrystallization only operates in the early stages of compression at 10^(-4)s^(-1).Dynamic recrystallization kinetics are enhanced at higher strain rates(10^(-2)s^(-1)and 0.5s^(-1))due to an increased contribution from twin-induced dynamic recrystallization.The present study reveals that the controlling mechanisms for continuous dynamic recrystallization are basalslip and 2ndorder pyramidalslip activity.Because the activation of slip systems is mainly determined by crystallographic orientation,continuous dynamic recrystallization behaviour varies with grain orientation according to their propensity for basal and 2ndorder pyramidal slip.展开更多
We theoretically and experimentally demonstrate that magnetic plasmonic gradient metasurfaces(GMSs) can convert a spatially propagating wave to a one-way edge state or vice versa with high efficiency. Consisting of an...We theoretically and experimentally demonstrate that magnetic plasmonic gradient metasurfaces(GMSs) can convert a spatially propagating wave to a one-way edge state or vice versa with high efficiency. Consisting of an array of ferrite rods with a rotation gradient introduced to the rod dimers in the unit cell, GMSs can covert an incident wave beam to a one-way edge state with efficiency over 77%, and almost fully radiate into free space from the one-way edge state. The phenomenon arises from the unidirectional coupling of the spatial electromagnetic wave with magnetic plasmonic GMSs, which is evidenced from the photonic band diagrams of the edge state.The one-way edge state can radiate to or be excited from air with different angles by either engineering the gradient of the GMSs or tuning the bias magnetic field. By designing magnetic plasmonic GMSs with more exquisite configurations, we can expect many more nonreciprocal properties, adding additional freedom in manipulating electromagnetic waves.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.010-63243095)the National Science Foundation of China(Grant Nos.92263101 and 12174200)。
文摘In the quasi-free electron model,the Fermi surface spreads into a sphere in the Brillouin zone,i.e.,the Fermi sphere.The Fermi sphere exists widely in metal systems,no matter whether the crystal is in a body-center cubic,face-center cubic,or hexagonal close-packed lattice.Here,we report a class of compounds stabilized at high pressure with Rubik’s cubic Fermi surface.
基金funded by the National Key Research and Development Program of China(2018YFB0104400)supported by the Beijing Natural Science Foundation(2214066)。
文摘To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavior,including 5%state of charge(SOC)with small current overcharge and resting until the temperature equilibrium under adiabatic conditions.The intrinsic thermal response and the self-excitation behaviour are analysed through temperature and voltage changes during the step overcharge period.Experimental results show that the deintercalated state of the cathode is highly correlated to self-heating parasitic reactions.Before reaching the upper limit of Negative/Positive(N/P)ratio,the temperature changes little,the heat generation is significantly induced by the reversible heat(endothermic)and ohmic heat,which could balance each other.Following that the lithium metal is gradually deposited on the surface of the anode and reacts with electrolyte upon overcharge,inducing selfheating side reaction.However,this spontaneous thermal reaction could be“self-extinguished”.When the lithium in cathode is completely deintercalated,the boundary point of overcharge is about 4.7 V(~148%SOC,>40℃),and from this point,the self-heating behaviour could be continuously triggered until thermal runaway(TR)without additional overcharge.The whole static and spontaneous process lasts for 115 h and the side reaction heat is beyond 320,000 J.The continuous self-excitation behavior inside the battery is attributed to the interaction between the highly oxidized cathode and the solvent,which leads to the dissolution of metal ions.The dissolved metal ions destroy the SEI(solid electrolyte interphase)film on the surface of the deposited Li of anode,which induces the thermal reaction between lithium metal and the solvent.The interaction between cathode,the deposited Li of anode,and solvent promotes the temperature of the battery to rise slowly.When the temperature of the battery reaches more than 60℃,the reaction between lithium metal and solvent is accelerated.After the temperature rises rapidly to the melting point of the separator,it triggers the thermal runaway of the battery due to the short circuit of the battery.
文摘This paper describes a micro-grid system and its monitoring system. This micro-grid system consists of generation systems, consumer electrical equipments, auxiliary equipments and the monitoring system. All the equipments have 485 communication interfaces. In order to monitor and manage this micro-grid system, we built a monitoring system, which contains modular instrument system and industrial personal computer. In order to keep real time, we adopt some measures in software and hardware. We adopt LABVIEW and its program modules in software and adopt modular instrument system in hardware. Supporting by the software and hardware, the micro-grid system can be safe and stable.
基金supported by the National Natural Science Foundation of China(NSFC)(No.61971193)the Natural Science Foundation of Shanghai(No.20ZR1416100)+2 种基金the Songshan Laboratory Pre-research Project(No.YYJC072022006)the Shanghai Aerospace Science and Technology Innovation Fund(No.SAST2022074)the Science and Technology Commission of Shanghai Municipality(No.22DZ2229004)。
文摘A sub-Nyquist radar receiver based on photonics-assisted compressed sensing is proposed.Cascaded dictionaries are applied to extract the delay and the Doppler frequency of the echo signals,which do not need to accumulate multiple echo periods and can achieve better Doppler accuracy.An experiment is performed.Radar echoes with different delays and Doppler frequencies are undersampled and successfully reconstructed to obtain the delay and Doppler information of the targets.Experimental results show that the average reconstruction error of the Doppler frequency is 5.33 kHz using an 8-μs radar signal under the compression ratio of 5.The proposed method provides a promising solution for the sub-Nyquist radar receiver.
基金supported by the National Natural Science Foundation of China(12372027 and 12211530028)the Natural Science Foundation of Shandong Province(ZR202011050038)Special Funds for the Basic Scientific Research Expenses of Central Government Universities(2472022X03006A).
文摘Elasto-capillarity phenomena are prevalent in various industrial fields such as mechanical engineering,material science,aerospace,soft robotics,and biomedicine.In this study,two typical peeling processes of slender beams driven by the parallel magnetic field are investigated based on experimental and theoretical analysis.The first is the adhesion of two parallel beams,and the second is the self-folding of a long beam.In these two cases,the energy variation method on the elastica is used,and then,the governing equations and transversality boundary conditions are derived.It is shown that the analytical solutions are in excellent agreement with the experimental data.The effects of magnetic induction intensity,distance,and surface tension on the deflection curve and peeling length of the elastica are fully discussed.The results are instrumental in accurately regulating elasto-capillarity in structures and provide insights for the engineering design of programmable microstructures on surfaces,microsensors,and bionic robots.
文摘Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.
文摘To satisfy the property requirements for biodegradable medical implants,Zn alloyed with low levels of Mg(≤0.8 wt%)has attracted increased research interest.In the present study,deformation twinning was observed in tensile tests and twinning appears to have an adverse impact on ductility.The profuse twinning in the as-cast Zn-Mg alloys accelerated crack growth in tension due to twinning impingement which caused local stress concentrations and initiates cracking.As-rolled Zn-Mg alloys have better ductility than their as-cast counterparts due to the inhibition of twinning by the refined Mg2Zn11 intermetallic phase and the finer grain size.
基金This work was supported by National Natural Science Foundation of China （Grant No. 51375371） and the High-Tech Projects of China （Grant Nos. 2015AA020303 and 2015AA042503）.
文摘Loss of function of large tissues is an urgent clinical problem. Although the artificial microfluidic network fabricated in large tis- sue-engineered constructs has great promise, it is still difficult to develop an efficient vessel-like design to meet the requirements of the biomimetic vascular network for tissue engineering applications. In this study, we used a facile approach to fabricate a branched and multi-level vessel-like network in a large muscle scaffolds by combining stereolithography （SL） technology and enzymatic crosslinking mechanism. The morphology of microchannel cross-sections was characterized using micro-computed tomography. The square cross-sections were gradually changed to a seamless circular microfluidic network, which is similar to the natural blood vessel. In the different micro-channels, the velocity greatly affected the attachment and spread of Human Umbilical Vein Endothelial Cell （HUVEC）-Green Fluorescent Protein （GFP）. Our study demonstrated that the branched and multi-level microchannel network simulates biomimetic microenvironments to promote endothelialization. The gelatin scaffolds in the circular vessel-like networks will likely support myoblast and surrounding tissue for clinical use.
基金financially supported by the ARC Discovery Project(No.DP200101408)support from the China Scholarship Council(CSC)+1 种基金the University of Queensland(UQ)the School of Mechanical and Mining Engineering for the CSC and TOP-UP scholarship。
文摘A heterogeneous lamella(HL)design strategy was applied to manipulate mechanical properties of a new cost-effective Fe_(35)Ni_(35)Cr_(25)Mo_(5)compositionally complicated alloy(CCA).The HL structure was produced by single-step heat treatment(800℃for 1 h)after cold rolling.This HL structure consists of alternative lamellae regions of coarse-grained FCC matrix(5-20μm),and regions containing ultra-fine grains or subgrains(200-500 nm)together with nanoprecipitates(20-500 nm)and annealing twins.As compared with other cost-effective CCAs,the 800℃annealed sample with HL structure demonstrated a comparable tensile property,with yield strength over 1.0 GPa and total elongation of~13%.Formation of the annealing twins and nanoprecipitates decorated HL structure was a result of the concurrent partial recrystallization and precipitation ofσphase at the shear bands with a high density of lattice defects(e.g.high-density dislocation walls and deformation twins).The latter restricted the growth of recrystallized grains,leading to the formation of ultrafine subgrains within the HL structure.The high yield strength resulted from the multistage hetero-deformation induced(HDI)strengthening and precipitation strengthening associated with heterogeneous lamella structures containing nanoprecipitates.The ductility was originated from the coexistence of multiple deformation mechanisms,which started with dislocation slip and formation of stacking faults at the initial stage,followed by nano-twinning at the higher strain level.This HL design strategy,comprising composition and thermomechanical process designs,and the resultant microstructure tuning,open a broader window for the development of cost-effective CCAs with enhanced performance.
基金financial support from the Queensland Centre for Advanced Materials Processing and Manufacturing(AMPAM)the ARC Research Hub for Advanced Manufacturing of Medical Devices(IH150100024)financial support from the Key Research and Development Program of Shaanxi Province(2019ZDLSF03-06)。
文摘This work investigates the strain rate dependence of dynamic recrystallization behaviour of high-purity zinc in room temperature compression under strain rates of 10^(-4)s^(-1),10-2s^(-1)and 0.5 s^(-1).Results from electron backscatter diffraction provide insight into the deformation and dynamic recrystallization mechanisms operative.Continuous dynamic recrystallization,twin-induced dynamic recrystallization,and discontinuous dynamic recrystallization are all active under compressive deformation at room temperature.Due to the high stacking fault energy of Zn,continuous dynamic recrystallization is the dominant mechanism while discontinuous dynamic recrystallization only operates in the early stages of compression at 10^(-4)s^(-1).Dynamic recrystallization kinetics are enhanced at higher strain rates(10^(-2)s^(-1)and 0.5s^(-1))due to an increased contribution from twin-induced dynamic recrystallization.The present study reveals that the controlling mechanisms for continuous dynamic recrystallization are basalslip and 2ndorder pyramidalslip activity.Because the activation of slip systems is mainly determined by crystallographic orientation,continuous dynamic recrystallization behaviour varies with grain orientation according to their propensity for basal and 2ndorder pyramidal slip.
基金National Natural Science Foundation of China(61771237, 61671232, 11574275)。
文摘We theoretically and experimentally demonstrate that magnetic plasmonic gradient metasurfaces(GMSs) can convert a spatially propagating wave to a one-way edge state or vice versa with high efficiency. Consisting of an array of ferrite rods with a rotation gradient introduced to the rod dimers in the unit cell, GMSs can covert an incident wave beam to a one-way edge state with efficiency over 77%, and almost fully radiate into free space from the one-way edge state. The phenomenon arises from the unidirectional coupling of the spatial electromagnetic wave with magnetic plasmonic GMSs, which is evidenced from the photonic band diagrams of the edge state.The one-way edge state can radiate to or be excited from air with different angles by either engineering the gradient of the GMSs or tuning the bias magnetic field. By designing magnetic plasmonic GMSs with more exquisite configurations, we can expect many more nonreciprocal properties, adding additional freedom in manipulating electromagnetic waves.
