Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air in...Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air injection with dual atomizing nozzles,for the thermal treatment of waste piles.Numerical simulations are employed to investigate the influence of various parameters,namely,nozzle height,nozzle tilt angle,inlet air velocity and air temperature,on the droplet diffusion process,spread area,droplet temperature,and droplet size distribution.The results show that reducing the nozzle height increases the temperature of droplets upon their deposition on the waste pile.Specifically,when the nozzle height is lowered to 1.5 m,the temperature of the droplets reaching the waste pile is 1℃higher than when the nozzle height is set at 2 m.Furthermore,an increase in the nozzle tilt angle expands the overlapping heating area.For instance,when the nozzle angle is increased from 15°to 30°,the overlapping spread area expands by 3.21 m2.Additionally,increasing the inlet air velocity enhances the droplet diffusion range.At an air velocity of 2 m/s,the droplet diffusion range grows to 14.4 m,representing a 6.7%increase compared to the nowind condition.While the average droplet diameter decreases to 1.53 mm,the droplet temperature decreases by 1℃.Moreover,the droplet temperature is found to become smaller as the ambient temperature inside the waste warehouse declines.Specifically,a 5℃reduction in the ambient temperature results in a 1℃decrease in the average temperature of the atomized droplets.The study concludes that a nozzle height of 1.5 m and a nozzle tilt angle of 30°effectively meet practical heating requirements.展开更多
For atoms in external electric fields,the hyperpolarizabilities are the coefficients describing the nonlinear interactions contributing to the induced energies at the fourth power of the applied electric fields.Accura...For atoms in external electric fields,the hyperpolarizabilities are the coefficients describing the nonlinear interactions contributing to the induced energies at the fourth power of the applied electric fields.Accurate evaluations of these coefficients for various systems are crucial for improving precision in advanced atom-based optical lattice clocks and for estimating field-induced effects in atoms for quantum information applications.However,there is a notable scarcity of research on atomic hyperpolarizabilities,especially in the relativistic realm.Our work addresses this gap by establishing a novel set of alternative formulas for the hyperpolarizability based on the fourth-order perturbation theory.These formulas offer a more reasonable regrouping of scalar and tensor components compared to previous formulas,thereby enhancing their correctness and applicability.To validate our formulas,we perform the calculations for the ground and low-lying excited pure states of few-electron atoms H,Li,and Be^(+).The highly accurate results obtained for the H atom could serve as benchmarks for further development of other theoretical methods.展开更多
Topological phases featuring non-Abelian charges have garnered significant attention in recent years.In parallel,the study of multiband exceptional topology in non-Hermitian systems has emerged as a prominent research...Topological phases featuring non-Abelian charges have garnered significant attention in recent years.In parallel,the study of multiband exceptional topology in non-Hermitian systems has emerged as a prominent research direction.In this study,we investigate a parity-time(PT)symmetric Hamiltonian,which hosts both conventional non-Abelian topological phases(NATPs)and hybrid phases.We propose an experimental scheme using spin-1 atoms with spin-orbit coupling trapped in two-dimensional(2D)lattices.Before adding a non-Hermitian term,we find the emergence of distinct topological phases mixed by two NATPs and establish their connection with NATPs theory.When a non-Hermitian term that preserves PT symmetry protection was introduced,stable second-order exceptional rings and third-order exceptional points emerge and they drive the edge states to manifest as discontinuous Fermi arcs in the surface Brillouin zone.However,with the variation of the non-Hermitian term,it is rather intriguing that two types of exceptional rings here transition from being internally tangent to externally tangent,transforming into a new topological phase equivalent to the Hermitian case.This research provides deeper insights into the nature of NATPs and the topological implications of exceptional structures,contributing to the field of topological physics.展开更多
The introduction of metal single atoms(SAs)into semiconductors can effectively optimize their electronic configuration and enhance their photocatalytic properties.Therefore,it is crucial to clarify the corresponding p...The introduction of metal single atoms(SAs)into semiconductors can effectively optimize their electronic configuration and enhance their photocatalytic properties.Therefore,it is crucial to clarify the corresponding principles and photocatalytic mechanisms for efficient and sustainable photocatalytic water remediation systems.Herein,a promising Fe single-atom photocatalyst(Fe_(SA)-CN)is obtained by anchoring Fe SAs in graphitic carbon nitride using a simple calcination strategy.Characterization and experimental results indicate that the modification of Fe SAs not only introduces a doping energy level,but also changes the valence band position,which expands the light absorption range,enhances the reduction ability of photogenerated electrons,and improves the separation and transfer of photogenerated charge carriers.Subsequently,contaminants adsorbed on the FeSA-CN surface trigger their oxidation removal by h^(+),and the H_(2)O_(2)generated via two-electron direct reductions is converted in situ into OH by self-Fenton reaction for the synergistic contaminant degradation.In summary,FeSA-CN offers a promising pathway for single-atom photocatalysts in water remediation because of outstanding contamination removal efficiency,adaptability,and stability.展开更多
In order to better build the neutral beam injector with negative ion source(NNBI),the pre-research on key technologies has been carried out for the comprehensive research facility for fusion technology(CRFFT).Cesium s...In order to better build the neutral beam injector with negative ion source(NNBI),the pre-research on key technologies has been carried out for the comprehensive research facility for fusion technology(CRFFT).Cesium seeding into negative-ion sources is a prerequisite to obtain the required negative hydrogen ion.The performance of ion source largely depends on the cesium conditions in the source.It is very necessary to quantitatively measure the amount of cesium in the source during the plasma on and off periods(vacuum stage).展开更多
Mg/MgH_(2) has garnered significant attention primarily due to its abundant availability and high gravimetric density.Nevertheless,its practical implementation hindered by its high thermodynamic stability and sluggish...Mg/MgH_(2) has garnered significant attention primarily due to its abundant availability and high gravimetric density.Nevertheless,its practical implementation hindered by its high thermodynamic stability and sluggish kinetics.Fortunately,the introduction of transition metal single atom(TM SA)catalysts has emerged as an effective method to enhance the hydrogen storage properties of Mg/MgH_(2).Among these catalysts,the synergistic effect of nanoconfinement and TM SAs plays a pivotal role in the hydriding/dehydriding kinetics of Mg/MgH_(2).However,the effects of varying TM SAs interacting with N modified confined materials on H_(2) adsorption and desorption and underlying mechanisms remain enigmatic.Leveraging DFT calculations,we investigated the potential of combining TM SA catalysts with N-modified Carbon nanomaterials(CNT)to enhance the hydrogenation/dehydrogenation of Mg/MgH_(2).TM SA N-CNTs-Mg/MgH_(2) heterojunction systems encompassing ten 3d/4d transition metals were designed and constructed.We systematically investigated the impact of TM SA N-CNTs on the hydrogen absorption and desorption properties of Mg/MgH_(2) by examining parameters such as the electronic localization function(ELF),distorted charge density distributions,adsorption energies,dissociation energies,electronegativity,and the D-band center.Notably,the energy barriers for Mg/MgH_(2) hydrogenation and dehydrogenation were significantly reduced by 0.2-0.7 eV and 1.6-2.2 eV,respectively,through the catalytic promotion of TM SA N-CNTs.Herein,a novel“electronic-ropeway”effect was proposed to elucidate the underlying mechanism responsible for enhancing the hydrogen absorption and desorption kinetics in Mg/MgH_(2).Specifically,the contribution degree of TM SA N-CNTs and system electronegativity emerged as effective descriptors for predicting the reduced hydrogenation/dehydrogenation energy barriers.It is anticipated that elucidating the role of TM SA-N-CNTs will pave the way for developing innovative strategies to enhance the hydrogen absorption and desorption kinetics of Mg/MgH_(2) systems,thereby providing valuable design principles for the construction of novel Mg/MgH_(2) hydrogen storage materials.展开更多
The vortex dynamics after the initial ring dark solitons in two-component ultracold Rydberg atomic systems have been investigated.The two parameters characterizing the Rydberg long-range interaction—namely,the Rydber...The vortex dynamics after the initial ring dark solitons in two-component ultracold Rydberg atomic systems have been investigated.The two parameters characterizing the Rydberg long-range interaction—namely,the Rydberg strength and the blockade radius—along with the initial depth,are identified as the main factors that affect the vortex dynamics.In the absence of Rydberg soft-core potential and spin-orbit coupling,the late vortex dipoles move along x-or y-axis first.However,this work demonstrates that,with certain Rydberg strength and blockade radius,the late vortex dipoles move towards the edge at an oblique angle to the coordinate axes,and it reveals that the Rydberg nonlocal nonlinear interaction shortens the lifetime of late vortices.When the intra-component and inter-component Rydberg strengths are different,the backgrounds of the two components gradually complement each other,and the lifetime of late vortices is significantly shortened.The presented results show that the Rydberg dressing breaks the rule that the initial average depth determines the number and paths of vortices.The motion features of vortex dipoles in the ultracold Rydberg atomic system have been ascertained,and their directions of movement can be predicted to some degree based on the rotation directions and initial positions of the vortices.展开更多
We consider a Bose-Einstein condensate loaded inside an optical cavity and exposed to two crossed coherent pump fields with same imbalance parameter γ.We identify different effects between pure standing wave fields(...We consider a Bose-Einstein condensate loaded inside an optical cavity and exposed to two crossed coherent pump fields with same imbalance parameter γ.We identify different effects between pure standing wave fields(γ=1)and the pump beams combining standing wave and running wave(γ≠1).In particular,for γ=1,the system only hosts a normal phase and a superradiant phase.In contrast,for γ≠1,the system features three distinctive phases:the normal phase(NP),superradiant phase 1(SR_(1)),and superradiant phase 2(SR_(2)).Importantly,the superradiance is subdivided into different types characterized by the photon phase.Furthermore,we determine perturbatively the phase boundary separating the normal phase and the superradiant phases,and find that there exists a competitive relationship of energy minimum on the overlapping region between SR_(1) and SR_(2).Interestingly,the transition between the normal phase to SR_(1) or SR_(2) is identified to be a second-order phase transition,while the transition between SR_(1) and SR_(2) is a first-order transition.When the first-order phase transition occurs,the phase of the photons changes abruptly from 0 to π/2.展开更多
Pure metal Fe films with thickness of about 100nm were deposited on Si （100） substrates by DC magnetron sputtering. Annealing was subsequently performed in a vacuum furnace in the temperature range of 600-1000℃ for...Pure metal Fe films with thickness of about 100nm were deposited on Si （100） substrates by DC magnetron sputtering. Annealing was subsequently performed in a vacuum furnace in the temperature range of 600-1000℃ for 2h. The samples were characterized by means of Rutherford backscattering （RBS） with 3MeV carbon ions. The RBS data were fitted with SIMNRA 6.0, and the results show the atomic interdiffusion in Fe/Si systems. The microstructures and crystal structures were characterized by scanning electron microscope and X-ray diffrac- tion. The effects of annealing on atomic interdiffusion, silicide formation, and microstructures in Fe/Si systems were analyzed.展开更多
The effect of high magnetic field on the atomic interdiffusion in Ni-Cu system was studied using the Cu/Ni/Cu diffusion couples. During the atomic interdiffusion in Ni-Cu system, it was found that the interdiffusion c...The effect of high magnetic field on the atomic interdiffusion in Ni-Cu system was studied using the Cu/Ni/Cu diffusion couples. During the atomic interdiffusion in Ni-Cu system, it was found that the interdiffusion coefficients increased with the increase of molar fraction of Ni atoms in the interdiffusion zones when the couples were annealed with or without the magnetic field. It was noted that all corresponding interdiffusion coefficients under the magnetic field are smaller than those without the magnetic field. The results demonstrate that the magnetic field retards the atomic interdiffusion in Ni-Cu system. This retardation is achieved through reducing the frequency factors but not changing the interdiffusion activation energies.展开更多
The origins of magnetism in transition-metal doped Na0.5Bi0.5TiO3 system are investigated by ab initio calculations. The calculated results indicate that a transition-metal atom sub- stitution for a Ti atom produces m...The origins of magnetism in transition-metal doped Na0.5Bi0.5TiO3 system are investigated by ab initio calculations. The calculated results indicate that a transition-metal atom sub- stitution for a Ti atom produces magnetic moments, which are due to the spin-polarization of transition-metal 3d electrons. The characteristics of exchange coupling are also calculated, which shows that in Cr-/Mn-/Fe-/Co- doped Na0.5Bi0.5TiO3 system, the antiferromagnetic coupling is favorable. The results can successfully explain the experimental phenomenon that, in Mn-/Fe- doped Nao.sBio.sTiO3 system, the ferromagnetism disappears at low tem- perature and the paramagnetic component becomes stronger with the increase of doping concentration of Mn/Fe/Co ions. Unexpectedly, we find the Na0.5Bi0.5Ti0.67V0.33iO3 sys- tem with ferromagnetic coupling is favorable and produces a magnetic moment of 2.00 P-B, which indicates that low temperature ferromagnetism materials could be made by intro- ducing V atoms in Na0.5Bi0.5TiO3. This may be a new way to produce low temperature multiferroic materials.展开更多
Comprehensively considering energy, volume and electronic structure of alloys, the ninth equation was determined as the interaction function of Nb-Mo alloys system in BCC structure on the basis of idea of systematic s...Comprehensively considering energy, volume and electronic structure of alloys, the ninth equation was determined as the interaction function of Nb-Mo alloys system in BCC structure on the basis of idea of systematic science of alloys, experimental lattice constants and heats of formation of disordered Nb（1-x）Mox alloys. The structural parameters and properties of Nb and Mo characteristic atoms sequences and corresponding characteristic crystals sequences were determined in Nb-Mo alloys system. The electronic structure and physical properties of disordered Nb（1-x）Mox alloys system were calculated according to concentration of characteristic atoms of disordered alloys. The change trend of physical properties is the same as that of electronic structure.展开更多
In this article,we conduct a study on mixed quasi-martingale Hardy spaces that are defined by means of the mixed L_(p)-norm.By utilizing Doob’s inequalities,we explore the atomic decomposition and quasi-martingale in...In this article,we conduct a study on mixed quasi-martingale Hardy spaces that are defined by means of the mixed L_(p)-norm.By utilizing Doob’s inequalities,we explore the atomic decomposition and quasi-martingale inequalities of mixed quasi-martingale Hardy spaces.Moreover,we furnish sufficient conditions for the boundedness ofσ-sublinear operators in these spaces.These findings extend the existing conclusions regarding mixed quasi-martingale Hardy spaces defined with the help of the mixed L_(p)-norm.展开更多
Scalability remains a major challenge in building practical fault-tolerant quantum computers.Currently,the largest number of qubits achieved across leading quantum platforms ranges from hundreds to thousands.In atom a...Scalability remains a major challenge in building practical fault-tolerant quantum computers.Currently,the largest number of qubits achieved across leading quantum platforms ranges from hundreds to thousands.In atom arrays,scalability is primarily constrained by the capacity to generate large numbers of optical tweezers,and conventional techniques using acousto-optic deflectors or spatial light modulators struggle to produce arrays much beyond∼10,000 tweezers.Moreover,these methods require additional microscope objectives to focus the light into micrometer-sized spots,which further complicates system integration and scalability.Here,we demonstrate the experimental generation of an optical tweezer array containing 280×280 spots using a metasurface,nearly an order of magnitude more than most existing systems.The metasurface leverages a large number of subwavelength phase-control pixels to engineer the wavefront of the incident light,enabling both large-scale tweezer generation and direct focusing into micron-scale spots without the need for a microscope.This result shifts the scalability bottleneck for atom arrays from the tweezer generation hardware to the available laser power.Furthermore,the array shows excellent intensity uniformity exceeding 90%,making it suitable for homogeneous single-atom loading and paving the way for trapping arrays of more than 10,000 atoms in the near future.展开更多
Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision,relatively small size among atomic gyroscopes,and promising potential for miniaturiza...Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision,relatively small size among atomic gyroscopes,and promising potential for miniaturization.In particular,the spin-exchange relaxation-free(SERF)atomic gyroscope relies on optical pumping to polarize atoms,enabling rotation sensing through the Faraday optical rotation angle(FORA).However,fluctuations in atomic density introduce systematic errors in FORA measurements,limiting long-term stability.We present a data-driven decoupling method that isolates atomic density fluctuations from the FORA signal by modeling spatially resolved light absorption in the vapor cell.The model accounts for the spatial distribution of spin polarization in the pump-light interaction volume,density-dependent relaxation rates,wall-induced relaxation,and polarization diffusion,and is implemented within a finite-element framework.Compared to the conventional Lambert-Beer law,which assumes one-dimensional homogeneity,our approach captures the full threedimensional density and polarization distribution,significantly improving the accuracy of light absorption modeling.The resulting absorption-density maps are used to train a feedforward neural network,yielding a high-precision estimator for atomic density fluctuations.This estimator enables the construction of a decoupling equation that separates the density contribution from the FORA signal.Experimental validation shows that this method improves the bias instability atσ(100 s)of the gyroscope was improved by 73.1%compared to traditional platinum-resistance-based stabilization.The proposed framework is general and can be extended to other optical pumping-based sensors,such as optically pumped magnetometers.展开更多
We prepared Co_(x)Pt_(100-x)(x=40,45,50,55,60)nanoparticles by the sol-gel method.The phase composition and crystal structure,morphology and microstructure,and magnetic properties of the samples were characterized and...We prepared Co_(x)Pt_(100-x)(x=40,45,50,55,60)nanoparticles by the sol-gel method.The phase composition and crystal structure,morphology and microstructure,and magnetic properties of the samples were characterized and tested using X-ray diffraction(XRD),transmission electron microscopy(TEM),and vibrating sample magnetometer(VSM),respectively.The results demonstrate that the coercivity of CoPt nanoparticles can be effectively controlled by adjusting the atomic ratio of Co and Pt in the samples.Among the compositions studied,the Co_(45)Pt_(55)sample synthesized by the sol-gel method exhibits smaller grain size and a coercivity as high as 6.65×10^(5) A/m is achieved.The morphology and microstructure of the nanoparticles were analyzed by TEM images,indicating that a slight excess of Pt can effectively enhance the coercivity of CoPt nanoparticles.展开更多
Single-atom catalysts(SACs)have demonstrated excellent performance in heterogeneous catalytic reactions owing to their maximized atomic efficiency,distinctive geometric,and electronic configurations.However,the effica...Single-atom catalysts(SACs)have demonstrated excellent performance in heterogeneous catalytic reactions owing to their maximized atomic efficiency,distinctive geometric,and electronic configurations.However,the efficacy of SACs remains limited for certain reactions requiring simultaneous activation of multiple reactants over metallic active sites.Herein,we report an atomically dispersed Pt1Ru1 dual-atom pair site anchored on nanodiamond@graphene(ND@G)for CO oxidation.The Pt1Ru1 dual-atom catalyst shows an exceptional turnover frequency(TOF)of 17.6.10^(-2)s^(-1)at significantly lower temperature(30℃),achieving a tenfold increase in TOF compared to singleatom Pt1/ND@G catalyst(1.5.10^(-2)s^(-1))and surpassing to previously reported Pt-based catalysts under similar conditions.Moreover,the catalyst demonstrates excellent stability,maintaining its activity for 40 h at 80℃without significant deactivation.The superior catalytic performance of Pt-Ru dual-atom catalysts is attributed to the synergistic effect between Pt and Ru atoms with enhanced metallicity for improving simultaneous adsorption and activation of CO and O_(2),and the tuning of conventional competitive reactant adsorption into a non-competitive pathway over dual-atom pair sites.The present work manifests the advantages of dual-atom pair sites in heterogeneous catalysis and paves the way for precise design of catalysts at the atomic scale.展开更多
The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for syn...The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for synthesizing thioesters primarily rely on the acylation of thiols,which produces substantial waste and requires malodorous,unstable sulfur sources.In this work,we introduce a photocatalyzed hydrogen transfer strategy that enables a three-component synthesis of thioesters using abundant primary alcohols,easily available alkenes and elemental sulfur under mild conditions.This protocol demonstrates broad applicability and high chemo-and regioselectivity for both primary alcohols and alkenes,highlighting the advantage and potential of photo-mediated hydrogen transfer in facilitating multicomponent reactions using primary alcohol and elemental sulfur feedstocks.展开更多
The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane(PEM)water electrolysis technology.Here,an Ir-skin cat...The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane(PEM)water electrolysis technology.Here,an Ir-skin catalyst(Ir@KM)is realized on a potassium-manganese oxide(K_(0.25)MnO_(x)(KM))using an ion-exchange method.The Ir-skin over the prepared Ir@KM has a low Ir-Ir atomic distance,endowing an energetically favorable oxide path mechanism to allow a low theoretical overpotential of 0.13 V.Ir@KM offers a low overpotential of~280 mV at a current density of 10 mA cm^(-2)and provides a high mass activity of up to 18,500 A at a cell voltage of 1.8 V in PEM,which is 17.6 times higher than that of IrO_(2),demonstrating a significant advantage in reducing the cost of the membrane electrode.The presented Ir-skin concept represents a promising strategy to fabricate low-Ir catalyst with high activity and durability for practical applications of PEM.展开更多
Ice premelting,the formation of a quasi-liquid layer on ice surfaces below the bulk melting point,plays a crucial role in various processes,ranging from glacier dynamics to ice friction and surface chemistry.Despite i...Ice premelting,the formation of a quasi-liquid layer on ice surfaces below the bulk melting point,plays a crucial role in various processes,ranging from glacier dynamics to ice friction and surface chemistry.Despite intensive research,the microscopic structure of the premelting layer and underlying molecular mechanisms remain poorly understood.In this work,we studied the temperature-and pressure-dependent structural disordering of crystalline Ih(0001)surface near the onset of premelting on the atomic scale by qPlus-based cryogenic atomic force microscopy.The linear correlation between the density of planar local structure(PLS)and the fraction of disordered surface region showed that the PLS mediated early-stage premelting by serving as a metastable seeding state.Notably,the associated surface disordering is cooperative,extending over an area of roughly~2 nm^(2) around a PLS.We further found a striking structural similarity between the kinetic-trapped regime below the surface crystallization temperature(T_(c))and the premelting-dominated regime above T_(c).As the deposition pressure increased,the characteristic temperature dependence was preserved,with only T_(c) shifting to higher values due to kinetic effects.Finally,we proposed a surface phase diagram for ice Ih(0001)based on our experimental observations.展开更多
文摘Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air injection with dual atomizing nozzles,for the thermal treatment of waste piles.Numerical simulations are employed to investigate the influence of various parameters,namely,nozzle height,nozzle tilt angle,inlet air velocity and air temperature,on the droplet diffusion process,spread area,droplet temperature,and droplet size distribution.The results show that reducing the nozzle height increases the temperature of droplets upon their deposition on the waste pile.Specifically,when the nozzle height is lowered to 1.5 m,the temperature of the droplets reaching the waste pile is 1℃higher than when the nozzle height is set at 2 m.Furthermore,an increase in the nozzle tilt angle expands the overlapping heating area.For instance,when the nozzle angle is increased from 15°to 30°,the overlapping spread area expands by 3.21 m2.Additionally,increasing the inlet air velocity enhances the droplet diffusion range.At an air velocity of 2 m/s,the droplet diffusion range grows to 14.4 m,representing a 6.7%increase compared to the nowind condition.While the average droplet diameter decreases to 1.53 mm,the droplet temperature decreases by 1℃.Moreover,the droplet temperature is found to become smaller as the ambient temperature inside the waste warehouse declines.Specifically,a 5℃reduction in the ambient temperature results in a 1℃decrease in the average temperature of the atomized droplets.The study concludes that a nozzle height of 1.5 m and a nozzle tilt angle of 30°effectively meet practical heating requirements.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174402 and 12393821)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB0920100 and XDB0920101)+2 种基金the Nature Science Foundation of Hubei Province(Grant Nos.2019CFA058 and 2022CFA013)supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)supported in part by NSF grant PHY-2116679.All the calculations are finished on the APM-Theoretical Computing Cluster(APMTCC)。
文摘For atoms in external electric fields,the hyperpolarizabilities are the coefficients describing the nonlinear interactions contributing to the induced energies at the fourth power of the applied electric fields.Accurate evaluations of these coefficients for various systems are crucial for improving precision in advanced atom-based optical lattice clocks and for estimating field-induced effects in atoms for quantum information applications.However,there is a notable scarcity of research on atomic hyperpolarizabilities,especially in the relativistic realm.Our work addresses this gap by establishing a novel set of alternative formulas for the hyperpolarizability based on the fourth-order perturbation theory.These formulas offer a more reasonable regrouping of scalar and tensor components compared to previous formulas,thereby enhancing their correctness and applicability.To validate our formulas,we perform the calculations for the ground and low-lying excited pure states of few-electron atoms H,Li,and Be^(+).The highly accurate results obtained for the H atom could serve as benchmarks for further development of other theoretical methods.
基金supported by the National Natural Science Foundation of China(Grant Nos.12274473 and 12135018).
文摘Topological phases featuring non-Abelian charges have garnered significant attention in recent years.In parallel,the study of multiband exceptional topology in non-Hermitian systems has emerged as a prominent research direction.In this study,we investigate a parity-time(PT)symmetric Hamiltonian,which hosts both conventional non-Abelian topological phases(NATPs)and hybrid phases.We propose an experimental scheme using spin-1 atoms with spin-orbit coupling trapped in two-dimensional(2D)lattices.Before adding a non-Hermitian term,we find the emergence of distinct topological phases mixed by two NATPs and establish their connection with NATPs theory.When a non-Hermitian term that preserves PT symmetry protection was introduced,stable second-order exceptional rings and third-order exceptional points emerge and they drive the edge states to manifest as discontinuous Fermi arcs in the surface Brillouin zone.However,with the variation of the non-Hermitian term,it is rather intriguing that two types of exceptional rings here transition from being internally tangent to externally tangent,transforming into a new topological phase equivalent to the Hermitian case.This research provides deeper insights into the nature of NATPs and the topological implications of exceptional structures,contributing to the field of topological physics.
基金financially supported by the National Natural Science Foundation of China(Nos.52100032 and 52350005)the Basic and Applied Basic Research Project of Guangzhou(Nos.2024A04J3679 and 2024A03J0088)+2 种基金the Introduced Innovative Research and Development Team Project under the“The Pearl River Talent Recruitment Program”of Guangdong Province(No.2019ZT08L387)the Opening Project of Shanxi Province Key Laboratory of Chemical Process Intensification,North University of China(No.2023-HOCE10)the National College Students’Innovation and Entrepreneurship Training Program(No.202211078135)
文摘The introduction of metal single atoms(SAs)into semiconductors can effectively optimize their electronic configuration and enhance their photocatalytic properties.Therefore,it is crucial to clarify the corresponding principles and photocatalytic mechanisms for efficient and sustainable photocatalytic water remediation systems.Herein,a promising Fe single-atom photocatalyst(Fe_(SA)-CN)is obtained by anchoring Fe SAs in graphitic carbon nitride using a simple calcination strategy.Characterization and experimental results indicate that the modification of Fe SAs not only introduces a doping energy level,but also changes the valence band position,which expands the light absorption range,enhances the reduction ability of photogenerated electrons,and improves the separation and transfer of photogenerated charge carriers.Subsequently,contaminants adsorbed on the FeSA-CN surface trigger their oxidation removal by h^(+),and the H_(2)O_(2)generated via two-electron direct reductions is converted in situ into OH by self-Fenton reaction for the synergistic contaminant degradation.In summary,FeSA-CN offers a promising pathway for single-atom photocatalysts in water remediation because of outstanding contamination removal efficiency,adaptability,and stability.
基金supported by the HFIPS Director’s Fund(Nos.YZJJQY202204 and 2021YZGH02)the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)+1 种基金the Natural Science Foundation of Anhui Province(No.2208085MA19)the National Key R&D Program of China(Nos.2017YFE300103 and 2017YFE300503)。
文摘In order to better build the neutral beam injector with negative ion source(NNBI),the pre-research on key technologies has been carried out for the comprehensive research facility for fusion technology(CRFFT).Cesium seeding into negative-ion sources is a prerequisite to obtain the required negative hydrogen ion.The performance of ion source largely depends on the cesium conditions in the source.It is very necessary to quantitatively measure the amount of cesium in the source during the plasma on and off periods(vacuum stage).
基金financed by the National Key Research and Development Program of China [grants number 2023YFB3809101]the National Natural Science Foundation of China [grants number 52471225, 52271212, 52201250]+1 种基金the Natural Science Foundation of Hebei Province [grants number E2018502054]the Fundamental Research Funds for the Central Universities [grants number 2023MS148]
文摘Mg/MgH_(2) has garnered significant attention primarily due to its abundant availability and high gravimetric density.Nevertheless,its practical implementation hindered by its high thermodynamic stability and sluggish kinetics.Fortunately,the introduction of transition metal single atom(TM SA)catalysts has emerged as an effective method to enhance the hydrogen storage properties of Mg/MgH_(2).Among these catalysts,the synergistic effect of nanoconfinement and TM SAs plays a pivotal role in the hydriding/dehydriding kinetics of Mg/MgH_(2).However,the effects of varying TM SAs interacting with N modified confined materials on H_(2) adsorption and desorption and underlying mechanisms remain enigmatic.Leveraging DFT calculations,we investigated the potential of combining TM SA catalysts with N-modified Carbon nanomaterials(CNT)to enhance the hydrogenation/dehydrogenation of Mg/MgH_(2).TM SA N-CNTs-Mg/MgH_(2) heterojunction systems encompassing ten 3d/4d transition metals were designed and constructed.We systematically investigated the impact of TM SA N-CNTs on the hydrogen absorption and desorption properties of Mg/MgH_(2) by examining parameters such as the electronic localization function(ELF),distorted charge density distributions,adsorption energies,dissociation energies,electronegativity,and the D-band center.Notably,the energy barriers for Mg/MgH_(2) hydrogenation and dehydrogenation were significantly reduced by 0.2-0.7 eV and 1.6-2.2 eV,respectively,through the catalytic promotion of TM SA N-CNTs.Herein,a novel“electronic-ropeway”effect was proposed to elucidate the underlying mechanism responsible for enhancing the hydrogen absorption and desorption kinetics in Mg/MgH_(2).Specifically,the contribution degree of TM SA N-CNTs and system electronegativity emerged as effective descriptors for predicting the reduced hydrogenation/dehydrogenation energy barriers.It is anticipated that elucidating the role of TM SA-N-CNTs will pave the way for developing innovative strategies to enhance the hydrogen absorption and desorption kinetics of Mg/MgH_(2) systems,thereby providing valuable design principles for the construction of novel Mg/MgH_(2) hydrogen storage materials.
基金supported by the Natural Science Foundation of Hubei Province of China(Grant No.2025AFB370)。
文摘The vortex dynamics after the initial ring dark solitons in two-component ultracold Rydberg atomic systems have been investigated.The two parameters characterizing the Rydberg long-range interaction—namely,the Rydberg strength and the blockade radius—along with the initial depth,are identified as the main factors that affect the vortex dynamics.In the absence of Rydberg soft-core potential and spin-orbit coupling,the late vortex dipoles move along x-or y-axis first.However,this work demonstrates that,with certain Rydberg strength and blockade radius,the late vortex dipoles move towards the edge at an oblique angle to the coordinate axes,and it reveals that the Rydberg nonlocal nonlinear interaction shortens the lifetime of late vortices.When the intra-component and inter-component Rydberg strengths are different,the backgrounds of the two components gradually complement each other,and the lifetime of late vortices is significantly shortened.The presented results show that the Rydberg dressing breaks the rule that the initial average depth determines the number and paths of vortices.The motion features of vortex dipoles in the ultracold Rydberg atomic system have been ascertained,and their directions of movement can be predicted to some degree based on the rotation directions and initial positions of the vortices.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174055 and 11674058)the Natural Science Foundation of Fujian Province,China(Grant No.2020J01195)。
文摘We consider a Bose-Einstein condensate loaded inside an optical cavity and exposed to two crossed coherent pump fields with same imbalance parameter γ.We identify different effects between pure standing wave fields(γ=1)and the pump beams combining standing wave and running wave(γ≠1).In particular,for γ=1,the system only hosts a normal phase and a superradiant phase.In contrast,for γ≠1,the system features three distinctive phases:the normal phase(NP),superradiant phase 1(SR_(1)),and superradiant phase 2(SR_(2)).Importantly,the superradiance is subdivided into different types characterized by the photon phase.Furthermore,we determine perturbatively the phase boundary separating the normal phase and the superradiant phases,and find that there exists a competitive relationship of energy minimum on the overlapping region between SR_(1) and SR_(2).Interestingly,the transition between the normal phase to SR_(1) or SR_(2) is identified to be a second-order phase transition,while the transition between SR_(1) and SR_(2) is a first-order transition.When the first-order phase transition occurs,the phase of the photons changes abruptly from 0 to π/2.
文摘Pure metal Fe films with thickness of about 100nm were deposited on Si （100） substrates by DC magnetron sputtering. Annealing was subsequently performed in a vacuum furnace in the temperature range of 600-1000℃ for 2h. The samples were characterized by means of Rutherford backscattering （RBS） with 3MeV carbon ions. The RBS data were fitted with SIMNRA 6.0, and the results show the atomic interdiffusion in Fe/Si systems. The microstructures and crystal structures were characterized by scanning electron microscope and X-ray diffrac- tion. The effects of annealing on atomic interdiffusion, silicide formation, and microstructures in Fe/Si systems were analyzed.
基金Project(2011CB012803) supported by the National Basic Research Program of ChinaProject(NCET-10-0278) supported by Program for New Century Excellent Talents in University,China
文摘The effect of high magnetic field on the atomic interdiffusion in Ni-Cu system was studied using the Cu/Ni/Cu diffusion couples. During the atomic interdiffusion in Ni-Cu system, it was found that the interdiffusion coefficients increased with the increase of molar fraction of Ni atoms in the interdiffusion zones when the couples were annealed with or without the magnetic field. It was noted that all corresponding interdiffusion coefficients under the magnetic field are smaller than those without the magnetic field. The results demonstrate that the magnetic field retards the atomic interdiffusion in Ni-Cu system. This retardation is achieved through reducing the frequency factors but not changing the interdiffusion activation energies.
文摘The origins of magnetism in transition-metal doped Na0.5Bi0.5TiO3 system are investigated by ab initio calculations. The calculated results indicate that a transition-metal atom sub- stitution for a Ti atom produces magnetic moments, which are due to the spin-polarization of transition-metal 3d electrons. The characteristics of exchange coupling are also calculated, which shows that in Cr-/Mn-/Fe-/Co- doped Na0.5Bi0.5TiO3 system, the antiferromagnetic coupling is favorable. The results can successfully explain the experimental phenomenon that, in Mn-/Fe- doped Nao.sBio.sTiO3 system, the ferromagnetism disappears at low tem- perature and the paramagnetic component becomes stronger with the increase of doping concentration of Mn/Fe/Co ions. Unexpectedly, we find the Na0.5Bi0.5Ti0.67V0.33iO3 sys- tem with ferromagnetic coupling is favorable and produces a magnetic moment of 2.00 P-B, which indicates that low temperature ferromagnetism materials could be made by intro- ducing V atoms in Na0.5Bi0.5TiO3. This may be a new way to produce low temperature multiferroic materials.
基金Project (50954006) supported by the National Natural Science Foundation of ChinaProject (2009GK3152) supported by the Hunan Science and Technology Department, China+1 种基金Project (201012) supported by the Hunan Provincial Construction Department, ChinaProject (K1003048-11) supported by the Changsha City Science and Technology Department, China
文摘Comprehensively considering energy, volume and electronic structure of alloys, the ninth equation was determined as the interaction function of Nb-Mo alloys system in BCC structure on the basis of idea of systematic science of alloys, experimental lattice constants and heats of formation of disordered Nb（1-x）Mox alloys. The structural parameters and properties of Nb and Mo characteristic atoms sequences and corresponding characteristic crystals sequences were determined in Nb-Mo alloys system. The electronic structure and physical properties of disordered Nb（1-x）Mox alloys system were calculated according to concentration of characteristic atoms of disordered alloys. The change trend of physical properties is the same as that of electronic structure.
基金Supported by the National Natural Science Foundation of China(11871195)。
文摘In this article,we conduct a study on mixed quasi-martingale Hardy spaces that are defined by means of the mixed L_(p)-norm.By utilizing Doob’s inequalities,we explore the atomic decomposition and quasi-martingale inequalities of mixed quasi-martingale Hardy spaces.Moreover,we furnish sufficient conditions for the boundedness ofσ-sublinear operators in these spaces.These findings extend the existing conclusions regarding mixed quasi-martingale Hardy spaces defined with the help of the mixed L_(p)-norm.
基金supported by the National Natural Science Foundation of China (Grant No.92576208)Tsinghua University Initiative Scientific Research Program+1 种基金Beijing Science and Technology Planning ProjectTsinghua University Dushi Program。
文摘Scalability remains a major challenge in building practical fault-tolerant quantum computers.Currently,the largest number of qubits achieved across leading quantum platforms ranges from hundreds to thousands.In atom arrays,scalability is primarily constrained by the capacity to generate large numbers of optical tweezers,and conventional techniques using acousto-optic deflectors or spatial light modulators struggle to produce arrays much beyond∼10,000 tweezers.Moreover,these methods require additional microscope objectives to focus the light into micrometer-sized spots,which further complicates system integration and scalability.Here,we demonstrate the experimental generation of an optical tweezer array containing 280×280 spots using a metasurface,nearly an order of magnitude more than most existing systems.The metasurface leverages a large number of subwavelength phase-control pixels to engineer the wavefront of the incident light,enabling both large-scale tweezer generation and direct focusing into micron-scale spots without the need for a microscope.This result shifts the scalability bottleneck for atom arrays from the tweezer generation hardware to the available laser power.Furthermore,the array shows excellent intensity uniformity exceeding 90%,making it suitable for homogeneous single-atom loading and paving the way for trapping arrays of more than 10,000 atoms in the near future.
基金supported by the Beijing Natural Science Foundation(Grant No.3252013)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0300402)+1 种基金the National Natural Science Foundation of China(Grant No.61673041)Key Area Research and Development Program of Guangdong Province(Grant No.2021B0101410005)。
文摘Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision,relatively small size among atomic gyroscopes,and promising potential for miniaturization.In particular,the spin-exchange relaxation-free(SERF)atomic gyroscope relies on optical pumping to polarize atoms,enabling rotation sensing through the Faraday optical rotation angle(FORA).However,fluctuations in atomic density introduce systematic errors in FORA measurements,limiting long-term stability.We present a data-driven decoupling method that isolates atomic density fluctuations from the FORA signal by modeling spatially resolved light absorption in the vapor cell.The model accounts for the spatial distribution of spin polarization in the pump-light interaction volume,density-dependent relaxation rates,wall-induced relaxation,and polarization diffusion,and is implemented within a finite-element framework.Compared to the conventional Lambert-Beer law,which assumes one-dimensional homogeneity,our approach captures the full threedimensional density and polarization distribution,significantly improving the accuracy of light absorption modeling.The resulting absorption-density maps are used to train a feedforward neural network,yielding a high-precision estimator for atomic density fluctuations.This estimator enables the construction of a decoupling equation that separates the density contribution from the FORA signal.Experimental validation shows that this method improves the bias instability atσ(100 s)of the gyroscope was improved by 73.1%compared to traditional platinum-resistance-based stabilization.The proposed framework is general and can be extended to other optical pumping-based sensors,such as optically pumped magnetometers.
基金Funded by the National Natural Science Foundation of China(No.52371169)。
文摘We prepared Co_(x)Pt_(100-x)(x=40,45,50,55,60)nanoparticles by the sol-gel method.The phase composition and crystal structure,morphology and microstructure,and magnetic properties of the samples were characterized and tested using X-ray diffraction(XRD),transmission electron microscopy(TEM),and vibrating sample magnetometer(VSM),respectively.The results demonstrate that the coercivity of CoPt nanoparticles can be effectively controlled by adjusting the atomic ratio of Co and Pt in the samples.Among the compositions studied,the Co_(45)Pt_(55)sample synthesized by the sol-gel method exhibits smaller grain size and a coercivity as high as 6.65×10^(5) A/m is achieved.The morphology and microstructure of the nanoparticles were analyzed by TEM images,indicating that a slight excess of Pt can effectively enhance the coercivity of CoPt nanoparticles.
基金supported by the National Key R&D Program of China(2021YFA1502802)the National Natural Science Foundation of China(U21B2092,22202213,22402210,22502215,22502214,22572200,and 22579171)+4 种基金the International Partnership Program of Chinese Academy of Sciences(172GJHZ2022028MI)the Shenyang Bureau of Science and Technology(24-213-3-25)the Natural Science Foundation of Liaoning Province(2025BS0153)Zhongke Technology Achievement Transfer and Transformation Center of Henan Province 2025119The XAS experiments were conducted in Beijing Synchrotron Radiation Facility(BSRF)and Shanghai Synchrotron Radiation Facility(SSRF).
文摘Single-atom catalysts(SACs)have demonstrated excellent performance in heterogeneous catalytic reactions owing to their maximized atomic efficiency,distinctive geometric,and electronic configurations.However,the efficacy of SACs remains limited for certain reactions requiring simultaneous activation of multiple reactants over metallic active sites.Herein,we report an atomically dispersed Pt1Ru1 dual-atom pair site anchored on nanodiamond@graphene(ND@G)for CO oxidation.The Pt1Ru1 dual-atom catalyst shows an exceptional turnover frequency(TOF)of 17.6.10^(-2)s^(-1)at significantly lower temperature(30℃),achieving a tenfold increase in TOF compared to singleatom Pt1/ND@G catalyst(1.5.10^(-2)s^(-1))and surpassing to previously reported Pt-based catalysts under similar conditions.Moreover,the catalyst demonstrates excellent stability,maintaining its activity for 40 h at 80℃without significant deactivation.The superior catalytic performance of Pt-Ru dual-atom catalysts is attributed to the synergistic effect between Pt and Ru atoms with enhanced metallicity for improving simultaneous adsorption and activation of CO and O_(2),and the tuning of conventional competitive reactant adsorption into a non-competitive pathway over dual-atom pair sites.The present work manifests the advantages of dual-atom pair sites in heterogeneous catalysis and paves the way for precise design of catalysts at the atomic scale.
基金National Natural Science Foundation of China (Nos.22071185 and 22271224)the Fundamental Research Funds for the Central Universities (No.2042019kf0008)Wuhan University startup funding for financial support。
文摘The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for synthesizing thioesters primarily rely on the acylation of thiols,which produces substantial waste and requires malodorous,unstable sulfur sources.In this work,we introduce a photocatalyzed hydrogen transfer strategy that enables a three-component synthesis of thioesters using abundant primary alcohols,easily available alkenes and elemental sulfur under mild conditions.This protocol demonstrates broad applicability and high chemo-and regioselectivity for both primary alcohols and alkenes,highlighting the advantage and potential of photo-mediated hydrogen transfer in facilitating multicomponent reactions using primary alcohol and elemental sulfur feedstocks.
基金supported by the Hainan Province Science and Technology Special Fund(ZDYF2023GXJS165)the National Natural Science Foundation of China(52164028,22109035,52274297)+2 种基金the Foundation of State Key Laboratory of Marine Resource Utilization in South China Sea(Hainan University,MRUKF2021029)the Start-up Research Foundation of Hainan University(KYQD(ZR)-20008,20084,21170)the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province。
文摘The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane(PEM)water electrolysis technology.Here,an Ir-skin catalyst(Ir@KM)is realized on a potassium-manganese oxide(K_(0.25)MnO_(x)(KM))using an ion-exchange method.The Ir-skin over the prepared Ir@KM has a low Ir-Ir atomic distance,endowing an energetically favorable oxide path mechanism to allow a low theoretical overpotential of 0.13 V.Ir@KM offers a low overpotential of~280 mV at a current density of 10 mA cm^(-2)and provides a high mass activity of up to 18,500 A at a cell voltage of 1.8 V in PEM,which is 17.6 times higher than that of IrO_(2),demonstrating a significant advantage in reducing the cost of the membrane electrode.The presented Ir-skin concept represents a promising strategy to fabricate low-Ir catalyst with high activity and durability for practical applications of PEM.
基金Project supported by the National Key R&D Program of China(Grant Nos.2021YFA1400500 and 2025YFF1502400)the National Natural Science Foundation of China(Grant Nos.92361302,12250001,12535001,and U22A20260)+3 种基金the China Postdoctoral Science Foundation(Grant Nos.BX20230021,2023T160011,and 2024M760068)support from the National Program for Support of Top-notch Young professionalssupport from Beijing Outstanding Young Scientist Program(Grant No.JWZQ20240101002)the New Cornerstone Science Foundation through the New Cornerstone Investigator Program and the XPLORER PRIZE。
文摘Ice premelting,the formation of a quasi-liquid layer on ice surfaces below the bulk melting point,plays a crucial role in various processes,ranging from glacier dynamics to ice friction and surface chemistry.Despite intensive research,the microscopic structure of the premelting layer and underlying molecular mechanisms remain poorly understood.In this work,we studied the temperature-and pressure-dependent structural disordering of crystalline Ih(0001)surface near the onset of premelting on the atomic scale by qPlus-based cryogenic atomic force microscopy.The linear correlation between the density of planar local structure(PLS)and the fraction of disordered surface region showed that the PLS mediated early-stage premelting by serving as a metastable seeding state.Notably,the associated surface disordering is cooperative,extending over an area of roughly~2 nm^(2) around a PLS.We further found a striking structural similarity between the kinetic-trapped regime below the surface crystallization temperature(T_(c))and the premelting-dominated regime above T_(c).As the deposition pressure increased,the characteristic temperature dependence was preserved,with only T_(c) shifting to higher values due to kinetic effects.Finally,we proposed a surface phase diagram for ice Ih(0001)based on our experimental observations.
