Owing to the utilization of lithium metal as anode with the ultrahigh theoretical capacity density of 3860 mA h g^(-1)and oxide-based ceramic solid-state electrolytes(SE),e.g.,garnet-type Li7La_(3)Zr_(2)O_(12)(LLZO),a...Owing to the utilization of lithium metal as anode with the ultrahigh theoretical capacity density of 3860 mA h g^(-1)and oxide-based ceramic solid-state electrolytes(SE),e.g.,garnet-type Li7La_(3)Zr_(2)O_(12)(LLZO),all-state-state lithium metal batteries(ASLMBs)have been widely accepted as the promising alternatives for providing the satisfactory energy density and safety.However,its applications are still challenged by plenty of technical and scientific issues.In this contribution,the co-sintering temperature at 500℃is proved as a compromise method to fabricate the composite cathode with structural integrity and declined capacity fading of LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM).On the other hand,it tends to form weaker grain boundary(GB)inside polycrystalline LLZO at inadequate sintering temperature for LLZO,which can induce the intergranular failure of SE during the growth of Li filament inside the unavoidable defect on the interface of SE.Therefore,increasing the strength of GB,refining the grain to 0.4μm,and precluding the interfacial defect are suggested to postpone the electro-chemo-mechanical failure of SE with weak GB.Moreover,the advanced sintering techniques to lower the co-sintering temperature for both NCM-LLZO composite cathode and LLZO SE can be posted out to realize the viability of state-of-the-art ASLMBs with higher energy density as well as the guaranteed safety.展开更多
We demonstrate an experimental method for the in situ temperature measurement of atomic vapor using the saturated absorption spectrum. By separately manipulating the frequency of the pump and probe beams, the position...We demonstrate an experimental method for the in situ temperature measurement of atomic vapor using the saturated absorption spectrum. By separately manipulating the frequency of the pump and probe beams, the position of the crossover peaks can move along the spectrum. Different velocity classes of atoms contribute to the crossover during the movement. We study the relationship between the intensity change of peaks and vapor temperature. Our experimental result around room temperature shows a deviation of less than 0.3 K. Compared with traditional thermometry using absorption spectroscopy, higher accuracy can theoretically be achieved with real-time thermometry.展开更多
China has the largest high-speed railway(HSR) system in the world, and it has gradually reshaped the urban network.The HSR system can be represented as different types of networks in terms of the nodes and various rel...China has the largest high-speed railway(HSR) system in the world, and it has gradually reshaped the urban network.The HSR system can be represented as different types of networks in terms of the nodes and various relationships(i.e.,linkages) between them. In this paper, we first introduce a general dual network model, including a physical network(PN)and a logical network(LN) to provide a comparative analysis for China’s high-speed rail network via complex network theory. The PN represents a layout of stations and rail tracks, and forms the basis for operating all trains. The LN is a network composed of the origin and destination stations of each high-speed train and the train flows between them. China’s high-speed railway(CHSR) has different topological structures and link strengths for PN in comparison with the LN. In the study, the community detection is used to analyze China’s high-speed rail networks and several communities are found to be similar to the layout of planned urban agglomerations in China. Furthermore, the hierarchies of urban agglomerations are different from each other according to the strength of inter-regional interaction and intra-regional interaction, which are respectively related to location and spatial development strategies. Moreover, a case study of the Yangtze River Delta shows that the hub stations have different resource divisions and are major contributors to the gap between train departure and arrival flows.展开更多
The total effective spin-exchange relaxation of naturally abundant Rb in a K–Rb–21Ne comagnetometer is analyzed,and the results show that the coexistence of 87Rb and 85Rb isotopes in the same volume can lead to a la...The total effective spin-exchange relaxation of naturally abundant Rb in a K–Rb–21Ne comagnetometer is analyzed,and the results show that the coexistence of 87Rb and 85Rb isotopes in the same volume can lead to a large extra spinexchange broadening compared to pure 87Rb.This broadening mainly comes from the contribution of the equivalent reduction in the Rb spin-exchange rate.On this basis,an approximate relaxation model is proposed and experimentally demonstrated to be more accurate than that from a previous work.This study also provides a method for determining the properties of alkali-metal vapor cells.展开更多
2D MXene(Ti_(3)CNT_(x))has been considered as the most promising electrode material for flexible supercapacitors owing to its metallic conductivity,ultra-high capacitance,and excellent flexibility.However,it suffers f...2D MXene(Ti_(3)CNT_(x))has been considered as the most promising electrode material for flexible supercapacitors owing to its metallic conductivity,ultra-high capacitance,and excellent flexibility.However,it suffers from a severe restacking problem during the electrode fabrication process,limiting the ion transport kinetics and the accessibility of ions in the electrodes,especially in the direction normal to the electrode surface.Herein,we report a NH_(3)-induced in situ etching strategy to fabricate 3D-interconnected porous MXene/carbon dots(p-MC)films for high-performance flexible supercapacitor.The pre-intercalated carbon dots(CDs)first prevent the restacking of MXene to expose more inner electrochemical active sites.The partially decomposed CDs generate NH_(3)for in situ etching of MXene nanosheets toward 3D-interconnected p-MC films.Benefiting from the structural merits and the 3D-interconnected ionic transmission channels,p-MC film electrodes achieve excellent gravimetric capacitance(688.9 F g^(-1)at 2 A g^(-1))and superior rate capability.Moreover,the optimized p-MC electrode is assembled into an asymmetric solid-state flexible supercapacitor with high energy density and superior cycling stability,demonstrating the great promise of p-MC electrode for practical applications.展开更多
The lubrication performance of liquids is severely restricted and is degraded in high-temperature environments. Stable and reliable lubrication in high temperature environments has been a long-standing goal in various...The lubrication performance of liquids is severely restricted and is degraded in high-temperature environments. Stable and reliable lubrication in high temperature environments has been a long-standing goal in various industrial fields. In this study,WS_(2)and Ti_(3)C_(2)T_(x)MXene nanoflakes were used as oil-based lubricant additives to generate ultra-low friction and even superlubricity(friction coefficient of ~0.007) at elevated temperatures(400℃), which has hitherto not been achieved by both individual pristine materials, WS_(2)and Ti_(3)C_(2)T_(x)MXene. Viscosity and thermogravimetric characterization revealed improvements in the high-temperature rheological properties and thermal stability of the lubricating base oil, indicating improved loadbearing and continuous lubrication capabilities at elevated temperatures. X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy demonstrated that the formation of an iron/titanium/tungsten-rich oxide lubricious thin film at the sliding interface reduced the interfacial shear stress, which was responsible for the observed friction and wear reductions at high contact pressures(> 1.1 GPa). Although the titanium/tungsten oxide film was gradually removed after prolonged sliding, a sufficiently thick iron oxide film maintained a low friction coefficient for at least 2 h. The improved surface quality facilitates the achievement of ultra-low friction and reduced wear. The proposed lubrication methodology has a broad utilization potential as a wear-reduction strategy across various industrial fields at elevated temperatures.展开更多
With the increasing demand for flexible piezoelectric sensor components,research on polyvinylidene fluoride(PVDF)based piezoelectric polymers is mounting up.However,the low dipole polarization and disordered polarizat...With the increasing demand for flexible piezoelectric sensor components,research on polyvinylidene fluoride(PVDF)based piezoelectric polymers is mounting up.However,the low dipole polarization and disordered polarization direction presented in PVDF hinder further improvement of piezoelectric properties.Here,we constructed an oriented tertiary structure,consisting of molecular chains,crystalline region,and MXene sheets,in MXene/PVDF nanocomposite via a temperature-pressure dual-field regulation method.The highly oriented PVDF molecular chains form approximately 90%of theβphase.In addition,the crystalline region structure with long-range orientation achieves out of plane polarization orientation.The parallel orientation arrangement of MXene effectively enhances the piezoelectric performances of the nanocomposite,and the current output of the device increases by nearly 23 times.This high output device is used to monitor exercise action,exploring the potential applications in wearable electronics.展开更多
Yield improvement has long been an important task for soybean breeding in the world in order to meet the increasing demand for food and animal feed.mi R396 genes have been shown to negatively regulate grain size in ri...Yield improvement has long been an important task for soybean breeding in the world in order to meet the increasing demand for food and animal feed.mi R396 genes have been shown to negatively regulate grain size in rice,but whether mi R396 family members may function in a similar manner in soybean is unknown.Here,we generated eight soybean mutants harboring different combinations of homozygous mutations in the six soybean mi R396genes through genome editing with clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated nuclease(Cas)12SF01 in the elite soybean cultivar Zhonghuang 302(ZH302).Four triple mutants(mir396aci,mir396acd,mir396adf,and mir396cdf),two quadruple mutants(mir396-abcd and mir396acfi),and two quintuple mutants(mir396abcdf and mir396bcdfi)were characterized.We found that plants of all the mir396 mutants produced larger seeds compared to ZH302 plants.Field tests showed that mir396adf and mir396cdf plants have significantly increased yield in growth zones with relatively high latitude which are suited for ZH302 and moderately increased yield in lower latitude.In contrast,mir396abcdf and mir396bcdfiplants have increased plant height and decreased yield in growth zones with relatively high latitude due to lodging issues,but they are suited for low latitude growth zones with increased yield without lodging problems.Taken together,our study demonstrated that loss-of-function of mi R396 genes leads to significantly enlarged seed size and increased yield in soybean,providing valuable germplasms for breeding high-yield soybean.展开更多
We propose a three-cavity coupled cavity optomechanical(COM)structure with tunable system parameters and theoretically investigate the probe-light transmission rate.Numerical calculation of the system’s spectra demon...We propose a three-cavity coupled cavity optomechanical(COM)structure with tunable system parameters and theoretically investigate the probe-light transmission rate.Numerical calculation of the system’s spectra demonstrates distinctive compound-induced transparency(CIT)characteristics,including multiple transparency windows and sideband dips,which can be explained by a coupling between optomechanically-induced transparency(OMIT)and electromagnetically-induced transparency.The effects of optical loss(gain)in the cavity,number and topology of active cavity,tunneling ratio,and pump laser power on the CIT spectrum are evaluated and analyzed.Moreover,the optical group delay of CIT is highly controllable and fast–slow light inter-transition can be achieved.The proposed structure makes possible the advantageous tuning freedom and provides a potential platform for controlling light propagation and fast–slow light switching.展开更多
This paper investigates the atomic spin polarization controllability of spin-exchange relaxation-free co-magnetometers(SERFCMs).This is the first work in the field of controllability analysis for the atomic spin ensem...This paper investigates the atomic spin polarization controllability of spin-exchange relaxation-free co-magnetometers(SERFCMs).This is the first work in the field of controllability analysis for the atomic spin ensembles systems,whose dynamic behaviors of spin polarization are described by the Bloch equations.Based on the Bloch equations,a state-space model of the atomic spin polarization for SERFCM is first established,which belongs to a particular class of nonlinear systems.For this class of nonlinear systems,a novel determination method for the global state controllability is proposed and proved.Then,this method is implemented in the process of controllability analysis on the atomic spin polarization of an actual SERFCM.Moreover,a theoretically feasible and reasonable solution of the control input is proposed under some physical constraints,with whose limitation of realistic conditions,the controller design can be accomplished more practically and more exactly.Finally,the simulation results demonstrate the feasibility and validation of the proposed controllability determination method.展开更多
The fringe noises disrupt the precise measurement of the atom distribution in the process of the absorption images.The fringe removal algorithms have been proposed to reconstruct the ideal reference images of the abso...The fringe noises disrupt the precise measurement of the atom distribution in the process of the absorption images.The fringe removal algorithms have been proposed to reconstruct the ideal reference images of the absorption images to remove the fringe noises.However,the focus of these fringe removal algorithms is the association of the fringe removal performance with the physical systems,leaving the gap to analyze the workflows of different fringe removal algorithms.This survey reviews the fringe removal algorithms and classifies them into two categories:the imagedecomposition based methods and the deep-learning based methods.Then this survey draws the workflow details of two classical fringe removal algorithms,and conducts experiments on the abs DL ultracold image dataset.Experiments show that the singular value decomposition(SVD)method achieves outstanding performance,and the U-net method succeeds in implying the image inpainting idea.The main contribution of this survey is the interpretation of the fringe removal algorithms,which may help readers have a better understanding of the research status.展开更多
The manipulating of optical waves in a microcavity is essential to developing the integrated optical devices.Generally,the two eigenmodes in a whispering-gallery-mode(WGM)microcavity possess chiral symmetry.Here we sh...The manipulating of optical waves in a microcavity is essential to developing the integrated optical devices.Generally,the two eigenmodes in a whispering-gallery-mode(WGM)microcavity possess chiral symmetry.Here we show the chiral symmetry breaking is induced by the asymmetric backscattering of counter-propagating optical waves in a whisperinggallery-mode(WGM)microcavity with a cavity-made slot filled with atomic vapor.Through tuning the dispersion relation of the atomic vapor in the cavity-made slot,the chiral modes are continuously steered.The mode frequency splitting in the transmission and reflection spectra stem from the chiral symmetry breaking of the two eigenmodes.The displacement sensitivity of the proposed system in response to the length variation of cavity-made slot exhibits a high sensitivity value of 15.22 THz/nm.展开更多
We study the quantum phase transition from a superfluid to a Mott insulator of ultracold atoms in a threedimensional optical lattice with adjustable filling factors.Based on the density-adjustable Bose-Einstein conden...We study the quantum phase transition from a superfluid to a Mott insulator of ultracold atoms in a threedimensional optical lattice with adjustable filling factors.Based on the density-adjustable Bose-Einstein condensate we prepared,the excitation spectrum in the superfluid and the Mott insulator regime is measured with different ensemble-averaged filling factors.We show that for the superfluid phase,the center of the excitation spectrum is positively correlated with the ensemble-averaged filling factor,indicating a higher sound speed of the system.For the Mott insulator phase,the discrete feature of the excitation spectrum becomes less pronounced as the ensemble-averaged filling factor increases,implying that it is harder for the system to enter the Mott insulator regime with higher filling factors.The ability to manipulate the filling factor affords further potential in performing quantum simulation with cold atoms trapped in optical lattices.展开更多
With several attractive properties, rotary lip seals are widely used in aircraft utility system, and their reliability estimation has drawn more and more attention. This work proposes a reliability estimation approach...With several attractive properties, rotary lip seals are widely used in aircraft utility system, and their reliability estimation has drawn more and more attention. This work proposes a reliability estimation approach based on time-varying dependence analysis. The dependence between the two performance indicators of rotary lip seals, namely leakage rate and friction torque, is modeled by time-varying copula function with polynomial to denote the time-varying parameters, and an efficient copula selection approach is utilized to select the optimal copula function. Parameter estimation is carried out based on a Bayesian method and the reliability during the whole lifetime is calculated based on a Monte Carlo method. Degradation test for rotary lip seal is conducted and the proposed model is validated by test data. The optimal copula function and optimal order of polynomial are determined based on test data. Results show that this model is effective in estimating the reliability of rotary lip seals and can achieve a better goodness of fit.展开更多
Formamidinium(FA)-based Sn-Pb perovskite solar cells(FAPb_(0.5)Sn_(0.5)I_(3) PSCs)with ideal bandgap and impressive thermal stability have caught enormous attention recently.However,it still suffers from the challenge...Formamidinium(FA)-based Sn-Pb perovskite solar cells(FAPb_(0.5)Sn_(0.5)I_(3) PSCs)with ideal bandgap and impressive thermal stability have caught enormous attention recently.However,it still suffers from the challenge of realizing high efficiency due to the surface imperfections of the transport materials and the energy-level mismatch between functional contacts.Herein,it is demonstrated that the modification on buried interface with alkali metal salts is a viable strategy to alleviate these issues.We systematically investigate the role of three alkali metal bromide salts(NaBr,KBr,CsBr)by burying them between the NiOx hole transport layer(HTL)and the perovskite light-absorbing layer,which can effectively passivate interface defects,improve energy-level matching and release the internal residual strain in perovskite layers.The device with CsBr buffer layer exhibits the best power conversion efficiency(PCE)approaching 20%,which is one of the highest efficiencies for FA-based Sn-Pb PSCs employing NiO_(x) HTLs.Impressively,the long-term storage stability of the unencapsulated device is also greatly boosted.Our work provides an efficient strategy to prepare desired FA-based ideal-bandgap Sn-Pb PSCs which could be applied in tandem solar cells.展开更多
Real-time monitoring of ball–shoe interactions can provide essential information for high-quality instruction in personalized soccer training,yet existing monitoring systems struggle to reflect specific forces,loci,a...Real-time monitoring of ball–shoe interactions can provide essential information for high-quality instruction in personalized soccer training,yet existing monitoring systems struggle to reflect specific forces,loci,and durations of action.Here,we design a self-powered piezoelectric sensor constructed by the gradient carbon nanotube/polyvinylidene fluoride(CNT/PVDF)composite to monitor the interactions between the ball and the shoe.Two-dimensional Raman mapping demonstrates the gradient structure of CNT/PVDF prepared by programmable electrospinning combined with a hot pressing.Benefitting from the synergistic effect of local polarization caused by the enrichment of CNT and the reduced diffusion of silver patterns in gradient structure,the as-prepared composite exhibits enhanced force-electric coupling with an excellent sensitivity of 80 mV/N and durability over 15,000 cycles.On this basis,we conformally attach a 3×3 sensor array to a soccer shoe,enabling real-time acquisition of kick position and contact force,which could provide quantitative assessment and personalize guidance for the training of soccer players.This self-powered piezoelectric sensor network system offers a promising paradigm for wearable monitoring under strong impact forces.展开更多
Magnetic expanded graphite(EG)hybrids were synthesized by co-intercalation polymerization of aniline together with transition metal ions.Experimental results show that metal ions(Fe,Co,Ni,Cu)and even their mixtures ca...Magnetic expanded graphite(EG)hybrids were synthesized by co-intercalation polymerization of aniline together with transition metal ions.Experimental results show that metal ions(Fe,Co,Ni,Cu)and even their mixtures can co-intercalate into graphite interlayers with flexibly controllable ratios and contents.Among these co-intercalation compounds,Fe/Ni-intercalated graphite with a predesigned mole ratio of 1:3 transforms into NiFe_(2)O_(4)/FeNi_(3)@EG during the annealing process.The synthesized magnetic EG hybrids present multiband microwave absorption in C and X bands due to improved impedance match as well as significantly enhanced interfacial polarization relaxation induced by multi-componential metals.The reflection values of−39.1 dB at 6.95 GHz and−25.7 dB at 9.4 GHz are achieved with an ultra-low loading of 5 wt.%.This work provides a flexible approach for tuning the components and structures of magnetic EG hybrids,which may contribute to the development of microwave absorption materials with superior performances.展开更多
The advancement of autonomous technology makes electric-powered drones an excellent choice for flexible logistics services at the last mile delivery stage.To reach a balance between green transportation and competitiv...The advancement of autonomous technology makes electric-powered drones an excellent choice for flexible logistics services at the last mile delivery stage.To reach a balance between green transportation and competitive edge,the collaborative routing of drones in the air and trucks on the ground is increasingly invested in the next generation of delivery,where it is particularly reasonable to consider customer time windows and time-dependent travel times as two typical time-related factors in daily services.In this paper,we propose the Vehicle Routing Problem with Drones under Time constraints(VRPD-T)and focus on the time constraints involved in realistic scenarios during the delivery.A mixed-integer linear programming model has been developed to minimize the total delivery completion time.Furthermore,to overcome the limitations of standard solvers in handling large-scale complex issues,a space-time hybrid heuristic-based algorithm has been developed to effectively identify a high-quality solution.The numerical results produced from randomly generated instances demonstrate the effectiveness of the proposed algorithm.展开更多
Unmanned Aerial Vehicle(UAV) navigation is aimed at guiding a UAV to the desired destinations along a collision-free and efficient path without human interventions, and it plays a crucial role in autonomous missions i...Unmanned Aerial Vehicle(UAV) navigation is aimed at guiding a UAV to the desired destinations along a collision-free and efficient path without human interventions, and it plays a crucial role in autonomous missions in harsh environments. The recently emerging Deep Reinforcement Learning(DRL) methods have shown promise for addressing the UAV navigation problem,but most of these methods cannot converge due to the massive amounts of interactive data when a UAV is navigating in high dynamic environments, where there are numerous obstacles moving fast.In this work, we propose an improved DRL-based method to tackle these fundamental limitations.To be specific, we develop a distributed DRL framework to decompose the UAV navigation task into two simpler sub-tasks, each of which is solved through the designed Long Short-Term Memory(LSTM) based DRL network by using only part of the interactive data. Furthermore, a clipped DRL loss function is proposed to closely stack the two sub-solutions into one integral for the UAV navigation problem. Extensive simulation results are provided to corroborate the superiority of the proposed method in terms of the convergence and effectiveness compared with those of the state-of-the-art DRL methods.展开更多
基金the National Natural Science Foundation of China(12102328)for supporting this work。
文摘Owing to the utilization of lithium metal as anode with the ultrahigh theoretical capacity density of 3860 mA h g^(-1)and oxide-based ceramic solid-state electrolytes(SE),e.g.,garnet-type Li7La_(3)Zr_(2)O_(12)(LLZO),all-state-state lithium metal batteries(ASLMBs)have been widely accepted as the promising alternatives for providing the satisfactory energy density and safety.However,its applications are still challenged by plenty of technical and scientific issues.In this contribution,the co-sintering temperature at 500℃is proved as a compromise method to fabricate the composite cathode with structural integrity and declined capacity fading of LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM).On the other hand,it tends to form weaker grain boundary(GB)inside polycrystalline LLZO at inadequate sintering temperature for LLZO,which can induce the intergranular failure of SE during the growth of Li filament inside the unavoidable defect on the interface of SE.Therefore,increasing the strength of GB,refining the grain to 0.4μm,and precluding the interfacial defect are suggested to postpone the electro-chemo-mechanical failure of SE with weak GB.Moreover,the advanced sintering techniques to lower the co-sintering temperature for both NCM-LLZO composite cathode and LLZO SE can be posted out to realize the viability of state-of-the-art ASLMBs with higher energy density as well as the guaranteed safety.
基金supported by the National Natural Science Foundation of China (Grant No. 61703025)。
文摘We demonstrate an experimental method for the in situ temperature measurement of atomic vapor using the saturated absorption spectrum. By separately manipulating the frequency of the pump and probe beams, the position of the crossover peaks can move along the spectrum. Different velocity classes of atoms contribute to the crossover during the movement. We study the relationship between the intensity change of peaks and vapor temperature. Our experimental result around room temperature shows a deviation of less than 0.3 K. Compared with traditional thermometry using absorption spectroscopy, higher accuracy can theoretically be achieved with real-time thermometry.
基金Project supported by the National Key Research and Development Program of China(Grant No.2019YFF0301400)the National Natural Science Foundation of China(Grant Nos.61671031,61722102,41722103,and 61961146005)。
文摘China has the largest high-speed railway(HSR) system in the world, and it has gradually reshaped the urban network.The HSR system can be represented as different types of networks in terms of the nodes and various relationships(i.e.,linkages) between them. In this paper, we first introduce a general dual network model, including a physical network(PN)and a logical network(LN) to provide a comparative analysis for China’s high-speed rail network via complex network theory. The PN represents a layout of stations and rail tracks, and forms the basis for operating all trains. The LN is a network composed of the origin and destination stations of each high-speed train and the train flows between them. China’s high-speed railway(CHSR) has different topological structures and link strengths for PN in comparison with the LN. In the study, the community detection is used to analyze China’s high-speed rail networks and several communities are found to be similar to the layout of planned urban agglomerations in China. Furthermore, the hierarchies of urban agglomerations are different from each other according to the strength of inter-regional interaction and intra-regional interaction, which are respectively related to location and spatial development strategies. Moreover, a case study of the Yangtze River Delta shows that the hub stations have different resource divisions and are major contributors to the gap between train departure and arrival flows.
基金Project supported by the National Key R&D Program of China(Grant Nos.2016YFB0501600 and 2017YFB0503100)the National Natural Science Foundation of China(Grant Nos.61773043,61673041,61721091,and 61703025)the National Science Fund for Distinguished Young Scholars of China(Grant No.61925301)。
文摘The total effective spin-exchange relaxation of naturally abundant Rb in a K–Rb–21Ne comagnetometer is analyzed,and the results show that the coexistence of 87Rb and 85Rb isotopes in the same volume can lead to a large extra spinexchange broadening compared to pure 87Rb.This broadening mainly comes from the contribution of the equivalent reduction in the Rb spin-exchange rate.On this basis,an approximate relaxation model is proposed and experimentally demonstrated to be more accurate than that from a previous work.This study also provides a method for determining the properties of alkali-metal vapor cells.
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of China(Grant Nos.21805261 and 51972277)Sichuan Science and Technology Program(Grant Nos.2021YFG0251 and 2022YFG0293)Fundamental Research Funds for the Central Universities(Grant No.2682021CX105)。
文摘2D MXene(Ti_(3)CNT_(x))has been considered as the most promising electrode material for flexible supercapacitors owing to its metallic conductivity,ultra-high capacitance,and excellent flexibility.However,it suffers from a severe restacking problem during the electrode fabrication process,limiting the ion transport kinetics and the accessibility of ions in the electrodes,especially in the direction normal to the electrode surface.Herein,we report a NH_(3)-induced in situ etching strategy to fabricate 3D-interconnected porous MXene/carbon dots(p-MC)films for high-performance flexible supercapacitor.The pre-intercalated carbon dots(CDs)first prevent the restacking of MXene to expose more inner electrochemical active sites.The partially decomposed CDs generate NH_(3)for in situ etching of MXene nanosheets toward 3D-interconnected p-MC films.Benefiting from the structural merits and the 3D-interconnected ionic transmission channels,p-MC film electrodes achieve excellent gravimetric capacitance(688.9 F g^(-1)at 2 A g^(-1))and superior rate capability.Moreover,the optimized p-MC electrode is assembled into an asymmetric solid-state flexible supercapacitor with high energy density and superior cycling stability,demonstrating the great promise of p-MC electrode for practical applications.
基金supported by the National Natural Science Foundation of China (Grant Nos. 52122507, 52350411, 52235004, and 52305214)the Sichuan Science and Technology Program (Grant Nos. 2023NSFSC1988, 2023YFSY0004)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. 2682021ZTPY095)the Independent Project of State Key Laboratory of Rail Transit Vehicle System (Grant No. 2023TPLT04)。
文摘The lubrication performance of liquids is severely restricted and is degraded in high-temperature environments. Stable and reliable lubrication in high temperature environments has been a long-standing goal in various industrial fields. In this study,WS_(2)and Ti_(3)C_(2)T_(x)MXene nanoflakes were used as oil-based lubricant additives to generate ultra-low friction and even superlubricity(friction coefficient of ~0.007) at elevated temperatures(400℃), which has hitherto not been achieved by both individual pristine materials, WS_(2)and Ti_(3)C_(2)T_(x)MXene. Viscosity and thermogravimetric characterization revealed improvements in the high-temperature rheological properties and thermal stability of the lubricating base oil, indicating improved loadbearing and continuous lubrication capabilities at elevated temperatures. X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy demonstrated that the formation of an iron/titanium/tungsten-rich oxide lubricious thin film at the sliding interface reduced the interfacial shear stress, which was responsible for the observed friction and wear reductions at high contact pressures(> 1.1 GPa). Although the titanium/tungsten oxide film was gradually removed after prolonged sliding, a sufficiently thick iron oxide film maintained a low friction coefficient for at least 2 h. The improved surface quality facilitates the achievement of ultra-low friction and reduced wear. The proposed lubrication methodology has a broad utilization potential as a wear-reduction strategy across various industrial fields at elevated temperatures.
基金the National Natural Science Foundation of China(No.52303328)the Postdoctoral Innovation Talents Support Program(No.BX20220257)+2 种基金the Multiple Clean Energy Harvesting System(No.YYF20223026)the Sichuan Science and Technology Program(No.2023NSFSC0313)a Catalyst Seeding General Grant administered by the Royal Society of New Zealand(Contract 20-UOA-035-CSG)。
文摘With the increasing demand for flexible piezoelectric sensor components,research on polyvinylidene fluoride(PVDF)based piezoelectric polymers is mounting up.However,the low dipole polarization and disordered polarization direction presented in PVDF hinder further improvement of piezoelectric properties.Here,we constructed an oriented tertiary structure,consisting of molecular chains,crystalline region,and MXene sheets,in MXene/PVDF nanocomposite via a temperature-pressure dual-field regulation method.The highly oriented PVDF molecular chains form approximately 90%of theβphase.In addition,the crystalline region structure with long-range orientation achieves out of plane polarization orientation.The parallel orientation arrangement of MXene effectively enhances the piezoelectric performances of the nanocomposite,and the current output of the device increases by nearly 23 times.This high output device is used to monitor exercise action,exploring the potential applications in wearable electronics.
基金supported by Bel agen Biotechnology Inc.,and by the National Key Research and Development Program of China(No.NK2022010301)the Seed-Industrialized Development Program in Shandong Province,China(No.2021LZGC003)+3 种基金the Key Research&Development Program of Shandong Province,China(No.2021LZGC012)the Innovative research team of Anhui Education(No.2022AH010056)the National Natural Science Foundation of China(No.32270367)the Ph D Scientific Research and Innovation Foundation of Sanya Yazhou Bay Science and Technology City(No.HSPHDSRF-2023-11-007)。
文摘Yield improvement has long been an important task for soybean breeding in the world in order to meet the increasing demand for food and animal feed.mi R396 genes have been shown to negatively regulate grain size in rice,but whether mi R396 family members may function in a similar manner in soybean is unknown.Here,we generated eight soybean mutants harboring different combinations of homozygous mutations in the six soybean mi R396genes through genome editing with clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated nuclease(Cas)12SF01 in the elite soybean cultivar Zhonghuang 302(ZH302).Four triple mutants(mir396aci,mir396acd,mir396adf,and mir396cdf),two quadruple mutants(mir396-abcd and mir396acfi),and two quintuple mutants(mir396abcdf and mir396bcdfi)were characterized.We found that plants of all the mir396 mutants produced larger seeds compared to ZH302 plants.Field tests showed that mir396adf and mir396cdf plants have significantly increased yield in growth zones with relatively high latitude which are suited for ZH302 and moderately increased yield in lower latitude.In contrast,mir396abcdf and mir396bcdfiplants have increased plant height and decreased yield in growth zones with relatively high latitude due to lodging issues,but they are suited for low latitude growth zones with increased yield without lodging problems.Taken together,our study demonstrated that loss-of-function of mi R396 genes leads to significantly enlarged seed size and increased yield in soybean,providing valuable germplasms for breeding high-yield soybean.
基金Project supported by the National Natural Science Foundation of China(Grant No.61575014)。
文摘We propose a three-cavity coupled cavity optomechanical(COM)structure with tunable system parameters and theoretically investigate the probe-light transmission rate.Numerical calculation of the system’s spectra demonstrates distinctive compound-induced transparency(CIT)characteristics,including multiple transparency windows and sideband dips,which can be explained by a coupling between optomechanically-induced transparency(OMIT)and electromagnetically-induced transparency.The effects of optical loss(gain)in the cavity,number and topology of active cavity,tunneling ratio,and pump laser power on the CIT spectrum are evaluated and analyzed.Moreover,the optical group delay of CIT is highly controllable and fast–slow light inter-transition can be achieved.The proposed structure makes possible the advantageous tuning freedom and provides a potential platform for controlling light propagation and fast–slow light switching.
基金supported in part by the National Natural Science Foundation of China(61673041,62003022)the Beijing Academy of Quantum Information Science Research Program(Y18G34)。
文摘This paper investigates the atomic spin polarization controllability of spin-exchange relaxation-free co-magnetometers(SERFCMs).This is the first work in the field of controllability analysis for the atomic spin ensembles systems,whose dynamic behaviors of spin polarization are described by the Bloch equations.Based on the Bloch equations,a state-space model of the atomic spin polarization for SERFCM is first established,which belongs to a particular class of nonlinear systems.For this class of nonlinear systems,a novel determination method for the global state controllability is proposed and proved.Then,this method is implemented in the process of controllability analysis on the atomic spin polarization of an actual SERFCM.Moreover,a theoretically feasible and reasonable solution of the control input is proposed under some physical constraints,with whose limitation of realistic conditions,the controller design can be accomplished more practically and more exactly.Finally,the simulation results demonstrate the feasibility and validation of the proposed controllability determination method.
基金founded by the National Natural Science Foundation of China(Grant No.62003020)。
文摘The fringe noises disrupt the precise measurement of the atom distribution in the process of the absorption images.The fringe removal algorithms have been proposed to reconstruct the ideal reference images of the absorption images to remove the fringe noises.However,the focus of these fringe removal algorithms is the association of the fringe removal performance with the physical systems,leaving the gap to analyze the workflows of different fringe removal algorithms.This survey reviews the fringe removal algorithms and classifies them into two categories:the imagedecomposition based methods and the deep-learning based methods.Then this survey draws the workflow details of two classical fringe removal algorithms,and conducts experiments on the abs DL ultracold image dataset.Experiments show that the singular value decomposition(SVD)method achieves outstanding performance,and the U-net method succeeds in implying the image inpainting idea.The main contribution of this survey is the interpretation of the fringe removal algorithms,which may help readers have a better understanding of the research status.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574021,61975005,and 11804017)the Fund from Beijing Academy of Quantum Information Sciences,China(Grant No.Y18G28).
文摘The manipulating of optical waves in a microcavity is essential to developing the integrated optical devices.Generally,the two eigenmodes in a whispering-gallery-mode(WGM)microcavity possess chiral symmetry.Here we show the chiral symmetry breaking is induced by the asymmetric backscattering of counter-propagating optical waves in a whisperinggallery-mode(WGM)microcavity with a cavity-made slot filled with atomic vapor.Through tuning the dispersion relation of the atomic vapor in the cavity-made slot,the chiral modes are continuously steered.The mode frequency splitting in the transmission and reflection spectra stem from the chiral symmetry breaking of the two eigenmodes.The displacement sensitivity of the proposed system in response to the length variation of cavity-made slot exhibits a high sensitivity value of 15.22 THz/nm.
基金Supported by the National Natural Science Foundation of China(Grant Nos.61703025,91736208,1150432&and 11920101004)the National Program on Key Basic Research Project of China(Grant Nos.2016YFA0301501 and 2017YFA0304204).
文摘We study the quantum phase transition from a superfluid to a Mott insulator of ultracold atoms in a threedimensional optical lattice with adjustable filling factors.Based on the density-adjustable Bose-Einstein condensate we prepared,the excitation spectrum in the superfluid and the Mott insulator regime is measured with different ensemble-averaged filling factors.We show that for the superfluid phase,the center of the excitation spectrum is positively correlated with the ensemble-averaged filling factor,indicating a higher sound speed of the system.For the Mott insulator phase,the discrete feature of the excitation spectrum becomes less pronounced as the ensemble-averaged filling factor increases,implying that it is harder for the system to enter the Mott insulator regime with higher filling factors.The ability to manipulate the filling factor affords further potential in performing quantum simulation with cold atoms trapped in optical lattices.
基金co-supported by the National Natural Science Foundation of China (51875015,51620105010,51675019)Natural Science Foundation of Beijing Municipality(L171003)。
文摘With several attractive properties, rotary lip seals are widely used in aircraft utility system, and their reliability estimation has drawn more and more attention. This work proposes a reliability estimation approach based on time-varying dependence analysis. The dependence between the two performance indicators of rotary lip seals, namely leakage rate and friction torque, is modeled by time-varying copula function with polynomial to denote the time-varying parameters, and an efficient copula selection approach is utilized to select the optimal copula function. Parameter estimation is carried out based on a Bayesian method and the reliability during the whole lifetime is calculated based on a Monte Carlo method. Degradation test for rotary lip seal is conducted and the proposed model is validated by test data. The optimal copula function and optimal order of polynomial are determined based on test data. Results show that this model is effective in estimating the reliability of rotary lip seals and can achieve a better goodness of fit.
基金support from the National Natural Science Foundation of China(No.61974106)the Core Facility of Wuhan University。
文摘Formamidinium(FA)-based Sn-Pb perovskite solar cells(FAPb_(0.5)Sn_(0.5)I_(3) PSCs)with ideal bandgap and impressive thermal stability have caught enormous attention recently.However,it still suffers from the challenge of realizing high efficiency due to the surface imperfections of the transport materials and the energy-level mismatch between functional contacts.Herein,it is demonstrated that the modification on buried interface with alkali metal salts is a viable strategy to alleviate these issues.We systematically investigate the role of three alkali metal bromide salts(NaBr,KBr,CsBr)by burying them between the NiOx hole transport layer(HTL)and the perovskite light-absorbing layer,which can effectively passivate interface defects,improve energy-level matching and release the internal residual strain in perovskite layers.The device with CsBr buffer layer exhibits the best power conversion efficiency(PCE)approaching 20%,which is one of the highest efficiencies for FA-based Sn-Pb PSCs employing NiO_(x) HTLs.Impressively,the long-term storage stability of the unencapsulated device is also greatly boosted.Our work provides an efficient strategy to prepare desired FA-based ideal-bandgap Sn-Pb PSCs which could be applied in tandem solar cells.
基金This work was financially supported by Sichuan Science and Technology Program(No.2023NSFSC0313)the Basic Research Cultivation Project(No.2682021ZTPY004)+1 种基金the Sichuan Province Foundation for Distinguished Young Team(No.20CXTD0106)Catalyst Seeding General Grant administered by the Royal Society of New Zealand(Contract 20-UOA-035-CSG).
文摘Real-time monitoring of ball–shoe interactions can provide essential information for high-quality instruction in personalized soccer training,yet existing monitoring systems struggle to reflect specific forces,loci,and durations of action.Here,we design a self-powered piezoelectric sensor constructed by the gradient carbon nanotube/polyvinylidene fluoride(CNT/PVDF)composite to monitor the interactions between the ball and the shoe.Two-dimensional Raman mapping demonstrates the gradient structure of CNT/PVDF prepared by programmable electrospinning combined with a hot pressing.Benefitting from the synergistic effect of local polarization caused by the enrichment of CNT and the reduced diffusion of silver patterns in gradient structure,the as-prepared composite exhibits enhanced force-electric coupling with an excellent sensitivity of 80 mV/N and durability over 15,000 cycles.On this basis,we conformally attach a 3×3 sensor array to a soccer shoe,enabling real-time acquisition of kick position and contact force,which could provide quantitative assessment and personalize guidance for the training of soccer players.This self-powered piezoelectric sensor network system offers a promising paradigm for wearable monitoring under strong impact forces.
基金the financial support of the National Natural Science Foundation of China(No.51573149)the Key R&D Projects in Sichuan Province(Nos.2020ZDZX0005 and 2020ZDZX0008).
文摘Magnetic expanded graphite(EG)hybrids were synthesized by co-intercalation polymerization of aniline together with transition metal ions.Experimental results show that metal ions(Fe,Co,Ni,Cu)and even their mixtures can co-intercalate into graphite interlayers with flexibly controllable ratios and contents.Among these co-intercalation compounds,Fe/Ni-intercalated graphite with a predesigned mole ratio of 1:3 transforms into NiFe_(2)O_(4)/FeNi_(3)@EG during the annealing process.The synthesized magnetic EG hybrids present multiband microwave absorption in C and X bands due to improved impedance match as well as significantly enhanced interfacial polarization relaxation induced by multi-componential metals.The reflection values of−39.1 dB at 6.95 GHz and−25.7 dB at 9.4 GHz are achieved with an ultra-low loading of 5 wt.%.This work provides a flexible approach for tuning the components and structures of magnetic EG hybrids,which may contribute to the development of microwave absorption materials with superior performances.
基金supported by the National Natural Science Foundation of China(No.61961146005)。
文摘The advancement of autonomous technology makes electric-powered drones an excellent choice for flexible logistics services at the last mile delivery stage.To reach a balance between green transportation and competitive edge,the collaborative routing of drones in the air and trucks on the ground is increasingly invested in the next generation of delivery,where it is particularly reasonable to consider customer time windows and time-dependent travel times as two typical time-related factors in daily services.In this paper,we propose the Vehicle Routing Problem with Drones under Time constraints(VRPD-T)and focus on the time constraints involved in realistic scenarios during the delivery.A mixed-integer linear programming model has been developed to minimize the total delivery completion time.Furthermore,to overcome the limitations of standard solvers in handling large-scale complex issues,a space-time hybrid heuristic-based algorithm has been developed to effectively identify a high-quality solution.The numerical results produced from randomly generated instances demonstrate the effectiveness of the proposed algorithm.
基金supported in part by the National Natural Science Foundation of China (Nos. 61671031, 61722102, and91738301)。
文摘Unmanned Aerial Vehicle(UAV) navigation is aimed at guiding a UAV to the desired destinations along a collision-free and efficient path without human interventions, and it plays a crucial role in autonomous missions in harsh environments. The recently emerging Deep Reinforcement Learning(DRL) methods have shown promise for addressing the UAV navigation problem,but most of these methods cannot converge due to the massive amounts of interactive data when a UAV is navigating in high dynamic environments, where there are numerous obstacles moving fast.In this work, we propose an improved DRL-based method to tackle these fundamental limitations.To be specific, we develop a distributed DRL framework to decompose the UAV navigation task into two simpler sub-tasks, each of which is solved through the designed Long Short-Term Memory(LSTM) based DRL network by using only part of the interactive data. Furthermore, a clipped DRL loss function is proposed to closely stack the two sub-solutions into one integral for the UAV navigation problem. Extensive simulation results are provided to corroborate the superiority of the proposed method in terms of the convergence and effectiveness compared with those of the state-of-the-art DRL methods.