Scalar fields should have no spin angular momentum according to conventional textbook understandings inclassical field theory.Yet,recent studies demonstrate the undoubted existence of wave spin endowed by acousticand ...Scalar fields should have no spin angular momentum according to conventional textbook understandings inclassical field theory.Yet,recent studies demonstrate the undoubted existence of wave spin endowed by acousticand elastic longitudinal waves,which are of irrotational curl-free nature without vorticity and can be describedby scalar fields.Moreover,the conventional theory cannot even answer the question of whether wave spin existsin dissipative fields,given the ubiquitous dissipation in reality.Here,to resolve the seeming paradox and answerthe challenging question,we uncover the origin of wave spin in scalar fields beyond traditional formalism byclarifying that the presence of higher-order derivatives in scalar field Lagrangians can give rise to non-vanishingwave spin.For“spinless”scalar fields of only first-order derivatives,we can make the hidden wave spin emergeby revealing a latent field that leads to the original field through a time derivative,thus giving higher-order termsin Lagrangian.Based on the standard Noether theorem approach,we exemplify the wave spin for unconventionaldrifted acoustic fields,and even for dissipative media,in scalar fields with higher-order derivative Lagrangian.The results would prompt people to build more comprehensive and fundamental understandings of structuralwave spin in classical fields.展开更多
The α-nucleus interaction is crucial in the description of α decay. Recently, we developed a pocket-type dynamical doublefolding potential(DDFP) that effectively incorporates both the surface-medium effect and inter...The α-nucleus interaction is crucial in the description of α decay. Recently, we developed a pocket-type dynamical doublefolding potential(DDFP) that effectively incorporates both the surface-medium effect and interior Pauli repulsion in α decay [H. Zheng et al., Phys. Rev. C 109, L011301(2024)]. This potential results in a pocket geometry within the nuclear surface region, which is consistent with the α-clustering characteristics predicted by microscopic calculations. In this study, the accuracy of the pocket-type DDFP was validated via systematic calculations of α-decay half-lives and an extended evaluation of the nuclear charge radii of the daughter nuclei. The results demonstrate good agreement with the experimental data for both quantities, thereby confirming the reliability of the DDFP model. Compared with calculations that use α-nucleus interactions derived from conventional double-folding procedures, DDFP employs fewer adjustable parameters to achieve a more accurate description of the charge radii based on the experimental α-decay energies.展开更多
In this study,we aim to clarify the luminescence and scintillation performance of 0.2 at%Pr^(3+)-doped LuYAG scintillators with either zirconium or hafnium co-doping obtained using the micro-pulling-down(μ-PD)method....In this study,we aim to clarify the luminescence and scintillation performance of 0.2 at%Pr^(3+)-doped LuYAG scintillators with either zirconium or hafnium co-doping obtained using the micro-pulling-down(μ-PD)method.Under radiation excitation,scintillation properties such as light yield,decay time,and afterglow level were measured and compared to non-co-doped LuYAG:Pr^(3+).The positive effect of Zr and Hf co-doping is to significantly shorten the scintillation time response.The negative effect is the decrease of scintillation yield and increase of afterglow.We propose that the positively charged defects induced by Zr/Hf co-doping are responsible for the spatial correlated traps around Pr centers causing the shortened scintillation decay via non-radiative recombination processes,and the deep traps as well for the prolonged afterglow.展开更多
Due to the rapid development and potential applications of iron(Ⅲ)-alginate(Fe-Alg)microgels in biomedical as well as environmental engineering,this study explores the preparation and characterization of spherical Fe...Due to the rapid development and potential applications of iron(Ⅲ)-alginate(Fe-Alg)microgels in biomedical as well as environmental engineering,this study explores the preparation and characterization of spherical Fe-Alg microgels using droplet microfluidics combined with an external ionic crosslinking method.This study focused on the role of Fe^(3+)and examined its effects on the physical/chemical properties of microgels under different ionic conditions and reduced or oxidized states.The pH-dependent release behavior of Fe^(3+)from these microgels demonstrates their potential biomedical and environmental applications.Furthermore,the microgels can exhibit magnetism simply by utilizing in situ oxidation,which can be further used for targeted drug delivery and magnetic separation technologies.展开更多
Using first-principles calculations, we study the tailoring of the electronic and magnetic properties of gallium sulfide nanoribbons（Ga2S2NRs） by mechanical strain. Hydrogen-passivated armchair-and zigzag-edged NRs...Using first-principles calculations, we study the tailoring of the electronic and magnetic properties of gallium sulfide nanoribbons（Ga2S2NRs） by mechanical strain. Hydrogen-passivated armchair-and zigzag-edged NRs（ANRs and ZNRs）with different widths are investigated. Significant effects in band gap and magnetic properties are found and analyzed. First,the band gaps and their nature of ANRs can be largely tailored by a strain. The band gaps can be markedly reduced, and show an indirect-direct（I-D） transition under a tensile strain. While under an increasing compressive strain, they undergo a series transitions of I-D-I-D. Five strain zones with distinct band structures and their boundaries are identified. In addition,the carrier effective masses of ANRs are also tunable by the strain, showing jumps at the boundaries. Second, the magnetic moments of（ferromagnetic） ZNRs show jumps under an increasing compressive strain due to spin density redistribution,but are unresponsive to tensile strains. The rich tunable properties by stain suggest potential applications of Ga2S2 NRs in nanoelectronics and optoelectronics.展开更多
Gold films deposited by direct current magnetron sputtering are used for synchrotron radiation optics. In this study, the microstructure and surface roughness of gold films were investigated for the purpose of develop...Gold films deposited by direct current magnetron sputtering are used for synchrotron radiation optics. In this study, the microstructure and surface roughness of gold films were investigated for the purpose of developing high-reflectivity mirrors. The deposition process was first optimized. Films were fabricated at different sputtering powers (15, 40, 80, and 120 W) and characterized using grazing incidence X-ray reflectometry, X-ray diffraction, and atomic force microscopy. The results showed that all the films were highly textured, having a dominant Au (111) orientation, and the film deposited at 80 W had the lowest surface roughness. Subsequently, post-deposition annealing from 100 to 200℃ in a vacuum was performed on the films deposited at 80 W to investigate the effect of annealing on the microstructure and surface roughness of the films. The grain size, surface roughness, and their relationship were investigated as a function of annealing temperature. AFM and XRD results revealed that at annealing temperatures of 175 ℃ and below, microstructural change of the films was mainly manifested by the elimination of voids. At annealing temperatures higher than 175℃, grain coalescence occurred in addition to the void elimination, causing the surface roughness to increase.展开更多
Atom lithography with chromium can be utilized to fabricate a pitch standard, which is chrectly traceable to me wavelength of the laser standing waves. The result of a calibrated commercial AFM measurement demonstrate...Atom lithography with chromium can be utilized to fabricate a pitch standard, which is chrectly traceable to me wavelength of the laser standing waves. The result of a calibrated commercial AFM measurement demonstrates that the pitch standard is （212.8±0.1） nm with a peak-to-valley-height （PTVH） better than 20 nm. The measurement results show the high period accuracy of traceability with the standing laser wavelength （λ/2 = 212.78 nm）. The Cr nano-grating covers a 1000μm×500 μm area, with a PTVH better than 10 nm. The feature width broadening of the Cr nanostructure has been experimentally observed along the direction of the standing waves. The PTVH along the Gaussian laser direction is similar to a Gaussian distribution. Highly uniform periodic nanostructures with a big area at the millimeter scale, and the surface growth uniformity of the Cr nano-grating, show its great potential in the application of a traceable pitch standard at trans-scales.展开更多
As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promot...As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.展开更多
The phase field crystal method and Continuum Modeling are applied to study the cooperative dislocation motion of the grain boundary(GB)migration,the manner of the nucleation of the grain and of the grain growth in two...The phase field crystal method and Continuum Modeling are applied to study the cooperative dislocation motion of the grain boundary(GB)migration,the manner of the nucleation of the grain and of the grain growth in two dimensions(2 D)under the deviatoric deformation at high temperature.Three types of the nucleation modes of new finding are observed by the phase field crystal simulation:The first mode of the nucleation is generated by the GB splitting into two sub-GBs;the second mode is of the reaction of the sub-GB dislocations,such as,the generation and annihilation of a pair of partial Frank sessile dislocation in 2 D.The process can be considered as the nucleation of dynamic recrystallization;the third mode is caused by two oncoming rows of the dislocations of these sub-GBs,crossing and passing each other to form new gap which is the nucleation place of the new deformed grain.The research is shown that due to the nucleation of different modes the mechanism of the grain growth by means of the sub-GB migration is different,and therefore,the grain growth rates are also different.Under the deviatoric deformation of the applied biaxial strain,the grain growth is faster than that of the grain growth without external applied stress.It is observed that the cooperative dislocation motion of the GB migration under the deviatoric deformation accompanies with local plastic flow and the state of the stress of the system changes sharply.When the system is in the process of recrystallized grain growth,the system energy is in an unstable state due to the release of the strain energy to cause that the reverse movement of the plastic flow occurs.The area growth of the deformed grain is approximately proportional to the strain square and also to the time square.The rule of the time square of the deformed grain growth can also be deduced by establishing the continuum dynamic equation of the biaxial strain-driven migration of the GB.The copper metal is taken as an example of the calculation,and the obtained result is a good agreement with that of the experiment.展开更多
The refining and modification effect of Ti (from GRAI), B, Sr and RE (cerium-riched mixtures of rare earth) on the mechanical properties of A356 aluminum alloys under T5 and T6 treatment condition were studied by OM, ...The refining and modification effect of Ti (from GRAI), B, Sr and RE (cerium-riched mixtures of rare earth) on the mechanical properties of A356 aluminum alloys under T5 and T6 treatment condition were studied by OM, SEM, EDAX, etc. It is found that the addition of RE to A356 alloys containing Ti and/or B and Sr makes strength and elongation increase in T6 treatment, but make elongation decrease in T5 treatment, at the same time, the long axis ofα(Al) grain structure decreases and the mean diameters of silicon particles increase with RE additions increasing. Grain refining with 0.01%Ti plus 0.03% B makes the dendriteα(Al) grain structure transform into equiaxed structure, resulting in obvious increase of elongation percentage. The mean diameters of silicon particles in T5 treatment are smaller than that in T6 treatment. Roundness of silicon particles in T5 treatment is higher than that in T6 treatment. A356 alloys modified and refined with Ti, B and Sr obtain the best mechanical properties in T5 treatment, however, the alloys with Ti, B, RE and Sr additions obtain the best mechanical properties in T6 treatment.展开更多
High quality 0.02 mol%,0.05 mol%,and 0.08 mol%Fe:β-Ga2O3 single crystals were grown by the floating zone method.The crystal structure,optical,electrical,and thermal properties were measured and discussed.Fe:β-Ga2O3 ...High quality 0.02 mol%,0.05 mol%,and 0.08 mol%Fe:β-Ga2O3 single crystals were grown by the floating zone method.The crystal structure,optical,electrical,and thermal properties were measured and discussed.Fe:β-Ga2O3 single crystals showed transmittance of higher than 80%in the near infrared region.With the increase of the Fe doping concentration,the optical bandgaps reduced and room temperature resistivity increased.The resistivity of 0.08 mol%Fe:β-Ga2O3 crystal reached to 3.63×1011Ω·cm.The high resistivity Fe:β-Ga2O3 single crystals could be applied as the substrate for the high-power field effect transistors(FETs).展开更多
Dy：Lu2O3 was grown by the float-zone （Fz） method. According to the absorption spectrum, the Judd-Ofelt （JO） parameters Ω2, Ω4, and Ω6 were calculated to be 4.86 × 10-20 cm2, 2.02 × 10-20 cm2, and 1.7...Dy：Lu2O3 was grown by the float-zone （Fz） method. According to the absorption spectrum, the Judd-Ofelt （JO） parameters Ω2, Ω4, and Ω6 were calculated to be 4.86 × 10-20 cm2, 2.02 × 10-20 cm2, and 1.76 ×10-20 cm2, respectively. The emission cross-section at 574 nm corresponding to the 4F9/2 →6H13/2 transition was calculated to be 0.53 ×10 20 cm2. The yellow （4F9/2 →6H13/2 transition） to blue （4F9/2 →6H15/2 transition） intensity ratio ranges up to 12.9. The fluorescence lifetime of the 4F9/2 energy level was measured to be 112.1 μs. These results reveal that Dy：Lu2O3 is a promising material for use in yellow lasers.展开更多
Boron carbide(B4C)coatings have high reflectivity and are widely used as mirrors for free-electron lasers in the x-ray range.However,B4C coatings fabricated by direct-current magnetron sputtering show a strong compres...Boron carbide(B4C)coatings have high reflectivity and are widely used as mirrors for free-electron lasers in the x-ray range.However,B4C coatings fabricated by direct-current magnetron sputtering show a strong compressive stress of about-3 GPa.By changing the argon gas pressure and nitrogen-argon gas mixing ratio,we are able to reduce the intrinsic stress to less than-1 GPa for a 50-nm-thick B4C coating.It is found that the stress in a coating deposited at 10 m Torr is-0.69 GPa,the rms roughness of the coating surface is 0.53 nm,and the coating reflectivity is 88%,which is lower than those of coatings produced at lower working pressures.When the working gas contains 8%nitrogen and 92%argon,the B4 C coating shows not only-1.19 GPa stress but also a low rms roughness of 0.16 nm,and the measured reflectivity is 93%at the wavelength of 0.154 nm.展开更多
The Solar Upper Transition Region Imager(SUTRI)focuses on the solar transition region to achieve dynamic imaging observation of the upper transition region.In this paper,we report the optical system design,mechanical ...The Solar Upper Transition Region Imager(SUTRI)focuses on the solar transition region to achieve dynamic imaging observation of the upper transition region.In this paper,we report the optical system design,mechanical design,ultrasmooth mirror manufacture and measurement,EUV multilayer film coating,prelaunch installation and calibration for the SUTRI payload at IPOE,Tongji University.Finally,the SUTRI carried by the SATech-01 satellite was successfully set to launch.All functions of this telescope were normal,and the observation results obtained in orbit were consistent with the design.展开更多
Metallic glasses are spatially heterogeneous at the nanometer scale.However,the effects of external excitation on their structural and mechanical heterogeneity and the correlation to their properties are still unresol...Metallic glasses are spatially heterogeneous at the nanometer scale.However,the effects of external excitation on their structural and mechanical heterogeneity and the correlation to their properties are still unresolved.Nanoindentation,atomic force microscopy(AFM) and high-resolution transmis sion elec tron micro scopy(HRTEM) were carried out to explore the effects of cryogenic thermal cycling(CTC) on mechanical/structural heterogeneity,nano sc ale creep deformation and optical properties of nano structured metallic glass thin films(MGTFs).The results indicate that CTC treatment alters the distribution fluctuations of hardness/modulus and energy dissipation and results in an increase-then-decrease variation in mechanical heterogeneity.By applying Maxwell-Voigt model,it can be shown that CTC treatment results in a remarkable activation of more defects with longer relaxation time in soft regions but has only a slight effect on defects in hard regions.In addition,CTC treatment increases the transition time from primary-state stage to steady-state stage during creep deformation.The enhanced optical reflectivity of the MGTFs after 15 thermal cycles can be attributed to increased aggregation of Cu and Ni elements.The results of this study shed new light on understanding mechanical/structural heterogeneity and its influence on nanoscale creep deformation and optical characteristics of nanostructured MGTFs,and facilitate the design of high-performance nanostructured MGTFs.展开更多
An energy model for the structure transformation of pile-ups of grain boundary dislocations(GBD)at the triple-junction of the grain boundary of ultrafine-grain materials was proposed.The energy of the pile-up of the G...An energy model for the structure transformation of pile-ups of grain boundary dislocations(GBD)at the triple-junction of the grain boundary of ultrafine-grain materials was proposed.The energy of the pile-up of the GBD in the system was calculated by the energy model,the critical geometric and mechanical conditions for the structure transformation of head dislocation of the pile-up were analyzed,and the influence of the number density of the dislocations and the angle between Burgers vectors of two decomposed dislocations on the transformation mode of head dislocation was discussed.The results show when the GBD is accumulated at triple junction,the head dislocation of the GBD is decomposed into two Burgers vectors of these dislocations unless the angle between the two vectors is less than 90°,and the increase of applied external stress can reduce the energy barrier of the dislocation decomposition.The mechanism that the ultrafine-grained metal material has both high strength and plasticity owing to the structure transformation of the pile-up of the GBD at the triple junction of the grain boundary is revealed.展开更多
Borophene allotropes have many unique physical properties due to their polymorphism and similarity between boron and carbon.In this work,based on the density functional theory and phonon Boltzmann transport equation,w...Borophene allotropes have many unique physical properties due to their polymorphism and similarity between boron and carbon.In this work,based on the density functional theory and phonon Boltzmann transport equation,we investigate the lattice thermal conductivityκof bothβ12 andχ3 borophene.Interestingly,these two allotropes with similar lattice structures have completely different thermal transport properties.β12 borophene has almost isotropicκaround 90 W/(m·K)at 300 K,whileκofχ3 borophene is much larger and highly anisotropic.The room temperatureκofχ3 borophene along the armchair direction is 512 W/(m·K),which is comparable to that of hexagonal boron nitride but much higher than most of the two-dimensional materials.The physical mechanisms responsible for such distinct thermal transport behavior are discussed based on the spectral phonon analysis.More interestingly,we uncover a unique one-dimensional transport feature of transverse acoustic phonon inχ3 borophene along the armchair direction,which results in a boost of phonon relaxation time and thus leads to the significant anisotropy and ultrahigh thermal conductivity inχ3 borophene.Our study suggests thatχ3 borophene may have promising application in heat dissipation,and also provides novel insights for enhancing the thermal transport in two-dimensional systems.展开更多
The layered pavements usually exhibit complicated mechanical properties with the effect of complex material properties under external environment.In some cases,such as launching missiles or rockets,layered pavements a...The layered pavements usually exhibit complicated mechanical properties with the effect of complex material properties under external environment.In some cases,such as launching missiles or rockets,layered pavements are required to bear large impulse load.However,traditional methods cannot non-destructively and quickly detect the internal structural of pavements.Thus,accurate and fast prediction of the mechanical properties of layered pavements is of great importance and necessity.In recent years,machine learning has shown great superiority in solving nonlinear problems.In this work,we present a method of predicting the maximum deflection and damage factor of layered pavements under instantaneous large impact based on random forest regression with the deflection basin parameters obtained from falling weight deflection testing.The regression coefficient R^(2)of testing datasets are above 0.94 in the process of predicting the elastic moduli of structural layers and mechanical responses,which indicates that the prediction results have great consistency with finite element simulation results.This paper provides a novel method for fast and accurate prediction of pavement mechanical responses under instantaneous large impact load using partial structural parameters of pavements,and has application potential in non-destructive evaluation of pavement structure.展开更多
Ionic liquids(ILs)have been widely applied in the one-step fabrication of perovskite with noticeable enhancement in the device performance.However,in-depth mechanism of ionic-liquid-assisted perovskite film formation ...Ionic liquids(ILs)have been widely applied in the one-step fabrication of perovskite with noticeable enhancement in the device performance.However,in-depth mechanism of ionic-liquid-assisted perovskite film formation is not well understood for also important two-step perovskite fabrication method,with better control of crystallization behavior.In this work,we introduced ionic liquid methylammonium formate(MAFa)into organic salt to produce perovskite film via a two-step method.Systematic investigations on the influence of MAFa on the perovskite thin film formation mechanism were performed.Ionic liquid is shown to assist lowering the perovskite formation enthalpy upon the density functional theory(DFT)calculation,leading to an accelerated crystallization process evidenced by in-situ UV-Vis absorption measurement.A gradient up-down distribution of ionic liquid has been confirmed by timeof-flight SIMS.Importantly,besides the surface passivation,we found the HCOO-can diffuse into the perovskite crystals to fill up the halide vacancies,resulting in significant reduction of trap states.Uniform perovskite films with significantly larger grains and less defect density were prepared with the help of MAFa IL,and the corresponding device efficiency over 23%was obtained by two-step process with remarkably improved stability.This research work provides an efficient strategy to tune the morphology and opto-electronic properties of perovskite materials via ionic-liquid-assisted two-step fabrication method,which is beneficial for upscaling and application of perovskite photovoltaics.展开更多
The crystal growth,x-ray diffraction pattern,absorption spectrum,emission spectrum,and fluorescence lifetime of a Tb：Lu2O3 single crystal were studied.Excited at 483 nm,the peak absorption cross-section was calculate...The crystal growth,x-ray diffraction pattern,absorption spectrum,emission spectrum,and fluorescence lifetime of a Tb：Lu2O3 single crystal were studied.Excited at 483 nm,the peak absorption cross-section was calculated to be 3.5×10（-22）cm2,and the full width at half maximum was found to be 2.85 nm.The Judd-Ofelt（J-O）intensity parameters 2,4,and 6 were computed to be 3.79×10（-20）cm2,1.30×10（-20）cm2,and 1.08×10（-20）cm2,with a spectroscopic quality factor 4/6 being 1.20.The emission cross-sections of green emission around 543 nm and yellow emission around 584 nm were calculated to be 9.43×10（-22）cm2 and 1.32×10（-22）cm2,respectively.The fluorescence lifetimeτexp of -5D4 was fitted to be 1.13 ms.The data suggest that the Tb：Lu2O3 crystal could be a potential candidate for green and yellow laser operation.展开更多
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1404400 and 2023YFA1406900)the Natural Science Foundation of Shanghai(Grant No.23ZR1481200)the Program of Shanghai Academic Research Leader(Grant No.23XD1423800)。
文摘Scalar fields should have no spin angular momentum according to conventional textbook understandings inclassical field theory.Yet,recent studies demonstrate the undoubted existence of wave spin endowed by acousticand elastic longitudinal waves,which are of irrotational curl-free nature without vorticity and can be describedby scalar fields.Moreover,the conventional theory cannot even answer the question of whether wave spin existsin dissipative fields,given the ubiquitous dissipation in reality.Here,to resolve the seeming paradox and answerthe challenging question,we uncover the origin of wave spin in scalar fields beyond traditional formalism byclarifying that the presence of higher-order derivatives in scalar field Lagrangians can give rise to non-vanishingwave spin.For“spinless”scalar fields of only first-order derivatives,we can make the hidden wave spin emergeby revealing a latent field that leads to the original field through a time derivative,thus giving higher-order termsin Lagrangian.Based on the standard Noether theorem approach,we exemplify the wave spin for unconventionaldrifted acoustic fields,and even for dissipative media,in scalar fields with higher-order derivative Lagrangian.The results would prompt people to build more comprehensive and fundamental understandings of structuralwave spin in classical fields.
基金supported by the National Natural Science Foundation of China(Nos.12035011,11975167,12175151,12005139,11947123)the Guangdong Major Project of Basic and Applied Basic Research(No.2021B0301030006)the Steady Support Program for Higher Education Institutions of Shenzhen(Nos.20200810163629001,20200817005440001).
文摘The α-nucleus interaction is crucial in the description of α decay. Recently, we developed a pocket-type dynamical doublefolding potential(DDFP) that effectively incorporates both the surface-medium effect and interior Pauli repulsion in α decay [H. Zheng et al., Phys. Rev. C 109, L011301(2024)]. This potential results in a pocket geometry within the nuclear surface region, which is consistent with the α-clustering characteristics predicted by microscopic calculations. In this study, the accuracy of the pocket-type DDFP was validated via systematic calculations of α-decay half-lives and an extended evaluation of the nuclear charge radii of the daughter nuclei. The results demonstrate good agreement with the experimental data for both quantities, thereby confirming the reliability of the DDFP model. Compared with calculations that use α-nucleus interactions derived from conventional double-folding procedures, DDFP employs fewer adjustable parameters to achieve a more accurate description of the charge radii based on the experimental α-decay energies.
基金supported by the National Key R&D Program of China(2022YFB3503900)National Natural Science Foundation of China(11975303,12211530561,12305211)+2 种基金Shanghai Municipal Natural Science Foundation(20ZR1473900,21TS1400100)CAS Cooperative Research Project(121631KYSB20210017)CAS Project for Young Scientist in Basic Research(YSBR-024)。
文摘In this study,we aim to clarify the luminescence and scintillation performance of 0.2 at%Pr^(3+)-doped LuYAG scintillators with either zirconium or hafnium co-doping obtained using the micro-pulling-down(μ-PD)method.Under radiation excitation,scintillation properties such as light yield,decay time,and afterglow level were measured and compared to non-co-doped LuYAG:Pr^(3+).The positive effect of Zr and Hf co-doping is to significantly shorten the scintillation time response.The negative effect is the decrease of scintillation yield and increase of afterglow.We propose that the positively charged defects induced by Zr/Hf co-doping are responsible for the spatial correlated traps around Pr centers causing the shortened scintillation decay via non-radiative recombination processes,and the deep traps as well for the prolonged afterglow.
基金financially supported by the Fundamental Research Funds for the Central Universities(No.KVJBMC23001536)Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing(No.20240518)+2 种基金the State Key Laboratory of Molecular Engineering of Polymers(Fudan University)(No.K2024-15)the Central Universities support from Beijing Jiaotong University(No.KVYJS24011536)the National Natural Science Foundation of China(No.62175012).
文摘Due to the rapid development and potential applications of iron(Ⅲ)-alginate(Fe-Alg)microgels in biomedical as well as environmental engineering,this study explores the preparation and characterization of spherical Fe-Alg microgels using droplet microfluidics combined with an external ionic crosslinking method.This study focused on the role of Fe^(3+)and examined its effects on the physical/chemical properties of microgels under different ionic conditions and reduced or oxidized states.The pH-dependent release behavior of Fe^(3+)from these microgels demonstrates their potential biomedical and environmental applications.Furthermore,the microgels can exhibit magnetism simply by utilizing in situ oxidation,which can be further used for targeted drug delivery and magnetic separation technologies.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174220 and 11374226)the Key Scientific Research Project of the Henan Institutions of Higher Learning,China(Grant No.16A140009)+2 种基金the Program for Innovative Research Team of Henan Polytechnic University,China(Grant Nos.T2015-3 and T2016-2)the Doctoral Foundation of Henan Polytechnic University,China(Grant No.B2015-46)the High-performance Grid Computing Platform of Henan Polytechnic University,China
文摘Using first-principles calculations, we study the tailoring of the electronic and magnetic properties of gallium sulfide nanoribbons（Ga2S2NRs） by mechanical strain. Hydrogen-passivated armchair-and zigzag-edged NRs（ANRs and ZNRs）with different widths are investigated. Significant effects in band gap and magnetic properties are found and analyzed. First,the band gaps and their nature of ANRs can be largely tailored by a strain. The band gaps can be markedly reduced, and show an indirect-direct（I-D） transition under a tensile strain. While under an increasing compressive strain, they undergo a series transitions of I-D-I-D. Five strain zones with distinct band structures and their boundaries are identified. In addition,the carrier effective masses of ANRs are also tunable by the strain, showing jumps at the boundaries. Second, the magnetic moments of（ferromagnetic） ZNRs show jumps under an increasing compressive strain due to spin density redistribution,but are unresponsive to tensile strains. The rich tunable properties by stain suggest potential applications of Ga2S2 NRs in nanoelectronics and optoelectronics.
基金supported by the National Key R&D Program of China(Nos.2016YFA0401304 and 2017YFA0403302)the National Natural Science Foundation of China(NSFC)(Nos.61621001,11505129,and U1732268)
文摘Gold films deposited by direct current magnetron sputtering are used for synchrotron radiation optics. In this study, the microstructure and surface roughness of gold films were investigated for the purpose of developing high-reflectivity mirrors. The deposition process was first optimized. Films were fabricated at different sputtering powers (15, 40, 80, and 120 W) and characterized using grazing incidence X-ray reflectometry, X-ray diffraction, and atomic force microscopy. The results showed that all the films were highly textured, having a dominant Au (111) orientation, and the film deposited at 80 W had the lowest surface roughness. Subsequently, post-deposition annealing from 100 to 200℃ in a vacuum was performed on the films deposited at 80 W to investigate the effect of annealing on the microstructure and surface roughness of the films. The grain size, surface roughness, and their relationship were investigated as a function of annealing temperature. AFM and XRD results revealed that at annealing temperatures of 175 ℃ and below, microstructural change of the films was mainly manifested by the elimination of voids. At annealing temperatures higher than 175℃, grain coalescence occurred in addition to the void elimination, causing the surface roughness to increase.
基金supported by the Major Research Plan of the National Natural Science Foundation of China(Grant No.91123022)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.10804084)
文摘Atom lithography with chromium can be utilized to fabricate a pitch standard, which is chrectly traceable to me wavelength of the laser standing waves. The result of a calibrated commercial AFM measurement demonstrates that the pitch standard is （212.8±0.1） nm with a peak-to-valley-height （PTVH） better than 20 nm. The measurement results show the high period accuracy of traceability with the standing laser wavelength （λ/2 = 212.78 nm）. The Cr nano-grating covers a 1000μm×500 μm area, with a PTVH better than 10 nm. The feature width broadening of the Cr nanostructure has been experimentally observed along the direction of the standing waves. The PTVH along the Gaussian laser direction is similar to a Gaussian distribution. Highly uniform periodic nanostructures with a big area at the millimeter scale, and the surface growth uniformity of the Cr nano-grating, show its great potential in the application of a traceable pitch standard at trans-scales.
基金supported by the National Key Research and Development Program of China (Grant No. 2016YFA0301101)the National Natural Science Foundation of China (Grant Nos. 91850206, 61621001, 2004284, 11674247, and 11974261)+3 种基金Shanghai Science and Technology Committee, China (Grant Nos. 18JC1410900 and 18ZR1442900)the China Postdoctoral Science Foundation (Grant Nos. 2019TQ0232 and 2019M661605)the Shanghai Super Postdoctoral Incentive ProgramFundamental Research Funds for the Central Universities, China
文摘As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.
基金supported by National Nature Science Foundation of China(Nos.51161003 and 51561031)Nature Science Foundation of Guangxi Province(No.2018GXNSFAA138150)。
文摘The phase field crystal method and Continuum Modeling are applied to study the cooperative dislocation motion of the grain boundary(GB)migration,the manner of the nucleation of the grain and of the grain growth in two dimensions(2 D)under the deviatoric deformation at high temperature.Three types of the nucleation modes of new finding are observed by the phase field crystal simulation:The first mode of the nucleation is generated by the GB splitting into two sub-GBs;the second mode is of the reaction of the sub-GB dislocations,such as,the generation and annihilation of a pair of partial Frank sessile dislocation in 2 D.The process can be considered as the nucleation of dynamic recrystallization;the third mode is caused by two oncoming rows of the dislocations of these sub-GBs,crossing and passing each other to form new gap which is the nucleation place of the new deformed grain.The research is shown that due to the nucleation of different modes the mechanism of the grain growth by means of the sub-GB migration is different,and therefore,the grain growth rates are also different.Under the deviatoric deformation of the applied biaxial strain,the grain growth is faster than that of the grain growth without external applied stress.It is observed that the cooperative dislocation motion of the GB migration under the deviatoric deformation accompanies with local plastic flow and the state of the stress of the system changes sharply.When the system is in the process of recrystallized grain growth,the system energy is in an unstable state due to the release of the strain energy to cause that the reverse movement of the plastic flow occurs.The area growth of the deformed grain is approximately proportional to the strain square and also to the time square.The rule of the time square of the deformed grain growth can also be deduced by establishing the continuum dynamic equation of the biaxial strain-driven migration of the GB.The copper metal is taken as an example of the calculation,and the obtained result is a good agreement with that of the experiment.
文摘The refining and modification effect of Ti (from GRAI), B, Sr and RE (cerium-riched mixtures of rare earth) on the mechanical properties of A356 aluminum alloys under T5 and T6 treatment condition were studied by OM, SEM, EDAX, etc. It is found that the addition of RE to A356 alloys containing Ti and/or B and Sr makes strength and elongation increase in T6 treatment, but make elongation decrease in T5 treatment, at the same time, the long axis ofα(Al) grain structure decreases and the mean diameters of silicon particles increase with RE additions increasing. Grain refining with 0.01%Ti plus 0.03% B makes the dendriteα(Al) grain structure transform into equiaxed structure, resulting in obvious increase of elongation percentage. The mean diameters of silicon particles in T5 treatment are smaller than that in T6 treatment. Roundness of silicon particles in T5 treatment is higher than that in T6 treatment. A356 alloys modified and refined with Ti, B and Sr obtain the best mechanical properties in T5 treatment, however, the alloys with Ti, B, RE and Sr additions obtain the best mechanical properties in T6 treatment.
基金the Scientific and Innovative Action Plan of Shanghai,China(Grant No.18511110502)Equipment Pre-research Fund Key Project,China(Grant No.6140922010601).
文摘High quality 0.02 mol%,0.05 mol%,and 0.08 mol%Fe:β-Ga2O3 single crystals were grown by the floating zone method.The crystal structure,optical,electrical,and thermal properties were measured and discussed.Fe:β-Ga2O3 single crystals showed transmittance of higher than 80%in the near infrared region.With the increase of the Fe doping concentration,the optical bandgaps reduced and room temperature resistivity increased.The resistivity of 0.08 mol%Fe:β-Ga2O3 crystal reached to 3.63×1011Ω·cm.The high resistivity Fe:β-Ga2O3 single crystals could be applied as the substrate for the high-power field effect transistors(FETs).
基金Project supported by the Fund of Key Laboratory of Optoelectronic Materials Chemistry and Physics,Chinese Academy of Sciences(Grant No.2008DP173016)the National Key Research and Development Program of China(Grant No.2016YFB1102202)the National Key Research and Development Program of China(Grant No.2016YFB0701002)
文摘Dy：Lu2O3 was grown by the float-zone （Fz） method. According to the absorption spectrum, the Judd-Ofelt （JO） parameters Ω2, Ω4, and Ω6 were calculated to be 4.86 × 10-20 cm2, 2.02 × 10-20 cm2, and 1.76 ×10-20 cm2, respectively. The emission cross-section at 574 nm corresponding to the 4F9/2 →6H13/2 transition was calculated to be 0.53 ×10 20 cm2. The yellow （4F9/2 →6H13/2 transition） to blue （4F9/2 →6H15/2 transition） intensity ratio ranges up to 12.9. The fluorescence lifetime of the 4F9/2 energy level was measured to be 112.1 μs. These results reveal that Dy：Lu2O3 is a promising material for use in yellow lasers.
基金Supported by the National Key R&D Program of China under Grant No 2016YFA0401304the National Natural Science Foundation of China under Grant Nos 61621001,U1732268 and 11875203the Shanghai Municipal Science and Technology Major Project under Grant No 2017SHZDZX02
文摘Boron carbide(B4C)coatings have high reflectivity and are widely used as mirrors for free-electron lasers in the x-ray range.However,B4C coatings fabricated by direct-current magnetron sputtering show a strong compressive stress of about-3 GPa.By changing the argon gas pressure and nitrogen-argon gas mixing ratio,we are able to reduce the intrinsic stress to less than-1 GPa for a 50-nm-thick B4C coating.It is found that the stress in a coating deposited at 10 m Torr is-0.69 GPa,the rms roughness of the coating surface is 0.53 nm,and the coating reflectivity is 88%,which is lower than those of coatings produced at lower working pressures.When the working gas contains 8%nitrogen and 92%argon,the B4 C coating shows not only-1.19 GPa stress but also a low rms roughness of 0.16 nm,and the measured reflectivity is 93%at the wavelength of 0.154 nm.
基金the National Key R&D Program of China(2022YFF0709101)the National Natural Science Foundation of China(NSFC)under grant Nos.61621001,62105244,12003016 and 12204353.
文摘The Solar Upper Transition Region Imager(SUTRI)focuses on the solar transition region to achieve dynamic imaging observation of the upper transition region.In this paper,we report the optical system design,mechanical design,ultrasmooth mirror manufacture and measurement,EUV multilayer film coating,prelaunch installation and calibration for the SUTRI payload at IPOE,Tongji University.Finally,the SUTRI carried by the SATech-01 satellite was successfully set to launch.All functions of this telescope were normal,and the observation results obtained in orbit were consistent with the design.
基金financially supported by the National Natural Science Foundation of China (Nos. 51971061 and 52231005)the Natural Science Foundation of Jiangsu Province (No. BK20221474)。
文摘Metallic glasses are spatially heterogeneous at the nanometer scale.However,the effects of external excitation on their structural and mechanical heterogeneity and the correlation to their properties are still unresolved.Nanoindentation,atomic force microscopy(AFM) and high-resolution transmis sion elec tron micro scopy(HRTEM) were carried out to explore the effects of cryogenic thermal cycling(CTC) on mechanical/structural heterogeneity,nano sc ale creep deformation and optical properties of nano structured metallic glass thin films(MGTFs).The results indicate that CTC treatment alters the distribution fluctuations of hardness/modulus and energy dissipation and results in an increase-then-decrease variation in mechanical heterogeneity.By applying Maxwell-Voigt model,it can be shown that CTC treatment results in a remarkable activation of more defects with longer relaxation time in soft regions but has only a slight effect on defects in hard regions.In addition,CTC treatment increases the transition time from primary-state stage to steady-state stage during creep deformation.The enhanced optical reflectivity of the MGTFs after 15 thermal cycles can be attributed to increased aggregation of Cu and Ni elements.The results of this study shed new light on understanding mechanical/structural heterogeneity and its influence on nanoscale creep deformation and optical characteristics of nanostructured MGTFs,and facilitate the design of high-performance nanostructured MGTFs.
基金financial supports from the National Natural Science Foundation of China(Nos.51161003,51561031)the Natural Science Foundation of Guangxi,China(No.2018GXNSFAA138150)。
文摘An energy model for the structure transformation of pile-ups of grain boundary dislocations(GBD)at the triple-junction of the grain boundary of ultrafine-grain materials was proposed.The energy of the pile-up of the GBD in the system was calculated by the energy model,the critical geometric and mechanical conditions for the structure transformation of head dislocation of the pile-up were analyzed,and the influence of the number density of the dislocations and the angle between Burgers vectors of two decomposed dislocations on the transformation mode of head dislocation was discussed.The results show when the GBD is accumulated at triple junction,the head dislocation of the GBD is decomposed into two Burgers vectors of these dislocations unless the angle between the two vectors is less than 90°,and the increase of applied external stress can reduce the energy barrier of the dislocation decomposition.The mechanism that the ultrafine-grained metal material has both high strength and plasticity owing to the structure transformation of the pile-up of the GBD at the triple junction of the grain boundary is revealed.
基金Project supported in part by the National Key Research and Development Program of China(Grant No.2016YFA0200901)the National Natural Science Foundation of China(Grant No.11890703)+2 种基金the Science and Technology Commission of Shanghai Municipality,China(Grant Nos.19ZR1478600 and18JC1410900)the Fundamental Research Funds for the Central Universities,China(Grant No.22120200069)the Open Fund of Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion(Grant No.2018TP1037201901)。
文摘Borophene allotropes have many unique physical properties due to their polymorphism and similarity between boron and carbon.In this work,based on the density functional theory and phonon Boltzmann transport equation,we investigate the lattice thermal conductivityκof bothβ12 andχ3 borophene.Interestingly,these two allotropes with similar lattice structures have completely different thermal transport properties.β12 borophene has almost isotropicκaround 90 W/(m·K)at 300 K,whileκofχ3 borophene is much larger and highly anisotropic.The room temperatureκofχ3 borophene along the armchair direction is 512 W/(m·K),which is comparable to that of hexagonal boron nitride but much higher than most of the two-dimensional materials.The physical mechanisms responsible for such distinct thermal transport behavior are discussed based on the spectral phonon analysis.More interestingly,we uncover a unique one-dimensional transport feature of transverse acoustic phonon inχ3 borophene along the armchair direction,which results in a boost of phonon relaxation time and thus leads to the significant anisotropy and ultrahigh thermal conductivity inχ3 borophene.Our study suggests thatχ3 borophene may have promising application in heat dissipation,and also provides novel insights for enhancing the thermal transport in two-dimensional systems.
基金Project supported in part by the National Natural Science Foundation of China(Grant No.12075168)the Fund from the Science and Technology Commission of Shanghai Municipality(Grant No.21JC1405600)。
文摘The layered pavements usually exhibit complicated mechanical properties with the effect of complex material properties under external environment.In some cases,such as launching missiles or rockets,layered pavements are required to bear large impulse load.However,traditional methods cannot non-destructively and quickly detect the internal structural of pavements.Thus,accurate and fast prediction of the mechanical properties of layered pavements is of great importance and necessity.In recent years,machine learning has shown great superiority in solving nonlinear problems.In this work,we present a method of predicting the maximum deflection and damage factor of layered pavements under instantaneous large impact based on random forest regression with the deflection basin parameters obtained from falling weight deflection testing.The regression coefficient R^(2)of testing datasets are above 0.94 in the process of predicting the elastic moduli of structural layers and mechanical responses,which indicates that the prediction results have great consistency with finite element simulation results.This paper provides a novel method for fast and accurate prediction of pavement mechanical responses under instantaneous large impact load using partial structural parameters of pavements,and has application potential in non-destructive evaluation of pavement structure.
基金supported by the National Natural Science Foundation of China(Grant Nos.62004129,51472189,22005202)the Shenzhen Science and Technology Innovation Commission(JCYJ20200109105003940)+2 种基金the Research Grants Council of Hong Kong(GRF grant 15221320,CRF C5037-18G,C7018-20G)the Hong Kong Polytechnic University Funds(Sir Sze-yuen Chung Endowed Professorship Fund(8-8480)RISE(Q-CDA5)。
文摘Ionic liquids(ILs)have been widely applied in the one-step fabrication of perovskite with noticeable enhancement in the device performance.However,in-depth mechanism of ionic-liquid-assisted perovskite film formation is not well understood for also important two-step perovskite fabrication method,with better control of crystallization behavior.In this work,we introduced ionic liquid methylammonium formate(MAFa)into organic salt to produce perovskite film via a two-step method.Systematic investigations on the influence of MAFa on the perovskite thin film formation mechanism were performed.Ionic liquid is shown to assist lowering the perovskite formation enthalpy upon the density functional theory(DFT)calculation,leading to an accelerated crystallization process evidenced by in-situ UV-Vis absorption measurement.A gradient up-down distribution of ionic liquid has been confirmed by timeof-flight SIMS.Importantly,besides the surface passivation,we found the HCOO-can diffuse into the perovskite crystals to fill up the halide vacancies,resulting in significant reduction of trap states.Uniform perovskite films with significantly larger grains and less defect density were prepared with the help of MAFa IL,and the corresponding device efficiency over 23%was obtained by two-step process with remarkably improved stability.This research work provides an efficient strategy to tune the morphology and opto-electronic properties of perovskite materials via ionic-liquid-assisted two-step fabrication method,which is beneficial for upscaling and application of perovskite photovoltaics.
基金Project supported by the National Natural Science Foundation of China(Grant No.61621001)the National Key Research and Development Program of China(Grant Nos.2016YFB1102202 and 2016YFB0701002)+1 种基金the Fundamental Research Funds for the Central Universities,Chinathe help of MOE Key Laboratory of Advanced Micro-Structured Materials and School of Physical Science and Technology,Guangxi University
文摘The crystal growth,x-ray diffraction pattern,absorption spectrum,emission spectrum,and fluorescence lifetime of a Tb：Lu2O3 single crystal were studied.Excited at 483 nm,the peak absorption cross-section was calculated to be 3.5×10（-22）cm2,and the full width at half maximum was found to be 2.85 nm.The Judd-Ofelt（J-O）intensity parameters 2,4,and 6 were computed to be 3.79×10（-20）cm2,1.30×10（-20）cm2,and 1.08×10（-20）cm2,with a spectroscopic quality factor 4/6 being 1.20.The emission cross-sections of green emission around 543 nm and yellow emission around 584 nm were calculated to be 9.43×10（-22）cm2 and 1.32×10（-22）cm2,respectively.The fluorescence lifetimeτexp of -5D4 was fitted to be 1.13 ms.The data suggest that the Tb：Lu2O3 crystal could be a potential candidate for green and yellow laser operation.
