Photonic crystal surface emitting lasers(PCSELs)utilize the Bragg diffraction of two-dimensional photonic crystals to achieve a single-mode output with a high power and a small divergence angle,and has recently attrac...Photonic crystal surface emitting lasers(PCSELs)utilize the Bragg diffraction of two-dimensional photonic crystals to achieve a single-mode output with a high power and a small divergence angle,and has recently attracted much attention^([1−3]).In 2023,Kyoto University reported GaAs-based 945 nm PCSELs with a continuous-wave(CW)single-mode output power of exceeding 50 W,and a narrow beam divergence angle of 0.05°,demonstrating a brightness of 1 GW·cm^(−2)·sr^(−1),which rivals those of the existing bulky lasers^([4]).展开更多
So far, the diffracted SAW field generated by an IDT with finite aperture on piezoelectric crystal surfaces is usually analyzed phenomenologically with the angular spectrum theory. A major approximation of this theory...So far, the diffracted SAW field generated by an IDT with finite aperture on piezoelectric crystal surfaces is usually analyzed phenomenologically with the angular spectrum theory. A major approximation of this theory is to ignore the vector nature of the field by assuming that the wave field can be represented by a scalar as in optics. In this paper, a rigorous vector field theory of the surface excitation of elastic wave field in piezoelectric crystal developed by the authors is used to evaluate the SAW diffraction field adepately and precisely. As an example, numerical results for YZ-LiNbO3 are presented and compared with those obtained form the angular spectrum theory.展开更多
For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatme...For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anticorrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(<40 mV).Even at 6 mA cm^(−2) and 3 mA h cm^(−2),it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO_(2) cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.展开更多
A geometric analysis technique for crystal growth and microstructure development in single-crystal welds had been previously developed.And the effect of welding conditions on the tendency of stray grains formation dur...A geometric analysis technique for crystal growth and microstructure development in single-crystal welds had been previously developed.And the effect of welding conditions on the tendency of stray grains formation during solidification was researched.In the present work,these analytical methods were further extended.Combined with an original vectorization method,a 3D Rosenthal solution was used to determine thermal conditions of the welds.Afterward,the dendrite growth orientation,the dendrite growth velocity and the thermal gradient along dendrite direction were calculated and lively plotted.Finally,the tendency of stray grains formation in the solidification front was forecasted and its distribution was presented with a 3D plot.The results indicate that substrate orientation has some impacts on the crystal growth pattern,dendrite growth velocity,distribution of thermal gradient and stray grain.Based on the research methods proposed in this work,any substrate crystallographic orientation can be studied,and predicted stray grains distribution can be visualized.展开更多
Effects of Re on the formation of surface eutectics have been investigated by using Ni-base single crystal superalloys with different Re additions. It was found that Re promotes the segregation of Al and Ta to the eut...Effects of Re on the formation of surface eutectics have been investigated by using Ni-base single crystal superalloys with different Re additions. It was found that Re promotes the segregation of Al and Ta to the eutectic melt, leading to an increase of the surface and internal eutectics. In addition, the addition of Re also increased the freezing range, the local solidification time, and the permeability of the dendritic network within the mushy zone. These factors ultimately promoted the outflow of the interdendritic residual liquid with the action of solidification shrinkage, and led to the formation of more surface eutectics. In contrast, the addition of Re had no obvious influence on the surface eutectic microstructures.展开更多
One new polymer [Co（L）（H2O）2]n（1） was synthesized by 4-（ethoxycarbonyl）-5-methyl-1H-1,2,3-triazole-1-carboxylic acid（Emtc） under the in situ solvent thermal reaction（H2L = 1-（carboxymethyl）-5-methyl-1H-1,...One new polymer [Co（L）（H2O）2]n（1） was synthesized by 4-（ethoxycarbonyl）-5-methyl-1H-1,2,3-triazole-1-carboxylic acid（Emtc） under the in situ solvent thermal reaction（H2L = 1-（carboxymethyl）-5-methyl-1H-1,2,3-triazole-4-carboxylic acid）. The title complex performs a wave-like 2D framework and the ligand H2L demonstrates the coordination mode as μ4-η-2：η-1η-1：η-1. The crystal structure has been established by single-crystal X-ray diffraction, and characterized by FT-IR. Fluorescent property was investigated in this work. Hirshfeld surface analysis has also been carried out on 1, and obvious main intermolecular interactions are observed.展开更多
The crystal structure of one novel Mn（II） complex, [Mn（pmta）_3]_2[Mn（H_2O）_6]·4H_2O（1）, is reported（Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid）. In the title compound, the asymmetric ...The crystal structure of one novel Mn（II） complex, [Mn（pmta）_3]_2[Mn（H_2O）_6]·4H_2O（1）, is reported（Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid）. In the title compound, the asymmetric unit consists of a [Mn（pmta_）3]ˉ anion, half [Mn（H_2O）_6]^（2＋） counter cation and two lattice H_2O molecules, and the intra- and intermolecular hydrogen bonds connect the complex into a supramolecular structure. The liquid-state fluorescence spectra of complex 1 have been determined. Hirshfeld surface analysis was also studied. The main intermolecular interactions in the complex are O···H and H···H contacts.展开更多
A vectorization analysis technique for crystal growth and microstructure development in single-crystal weld was developed in our previous work. Based on the vectorization method, crystal growth and stray grain distrib...A vectorization analysis technique for crystal growth and microstructure development in single-crystal weld was developed in our previous work. Based on the vectorization method, crystal growth and stray grain distribution in laser surface remelting of single crystal superalloy CMSX-4 were investigated in com- bination of simulations with experimental observations. The energy distribution of laser was taken into consideration in this research. The experimental results demonstrate that the simulation model applies well in the prediction of dendrite growth direction. Moreover, the prediction of stray grain distribution works well except for the region of dendrites growing along the [100] direction.展开更多
Alkanes are present in the atmosphere,commonly in the form of aerosols,and can thus interact with water droplets,leading to the formation of new interfaces.Yet,in the study of these interactions,traditional experiment...Alkanes are present in the atmosphere,commonly in the form of aerosols,and can thus interact with water droplets,leading to the formation of new interfaces.Yet,in the study of these interactions,traditional experimental methods often rely on the presence of sample containers,which can interfere with the observations.Acoustic levitation is a technique which allows the manipulation of samples in the microliter regime in a contact-free manner.Hence,interfacial phenomena can be studied without the presence of external surfaces,mimicking atmospheric conditions.Herein,we acoustically levitated a droplet of water in contact with a droplet of hexadecane and observed interfacial crystallization at the hexadecane/water interface that propagated to the entire droplet of hexadecane.It was found that the crystallization occurred up to 3 K above the melting temperature of hexadecane,and at a relative humidity below 30%.Moreover,the volume ratio between water and hexadecane influenced the fraction of crystallized surface area;for a hexadecane:water ratio above 1:2 full surface crystallization occurred.Combining acoustic levitation with Raman spectroscopy allowed the characterization of the phase transition in real time,demonstrating the existence of a solid crystal of alkane upon water evaporation.This study provides insights into the process of interfacial crystallization of hexadecane and demonstrates the suitability of acoustic levitation to study contact-free interfacial phenomena between two immiscible liquids.展开更多
The adsorption of one monolayer Fe atoms on an ideal GaAs (100) surface is studied by using the self-consistent tight-binding linear muffin-tin orbital method. The Fe adatom chemisorption on Ga- and As-terminatedsurfa...The adsorption of one monolayer Fe atoms on an ideal GaAs (100) surface is studied by using the self-consistent tight-binding linear muffin-tin orbital method. The Fe adatom chemisorption on Ga- and As-terminatedsurface are considered separately. A monolayer of S atoms is used to saturate the dangling bonds on one of the supercellsurfaces. Energies of adsorption systems of an Fe atom on different sites are calculated, and the charge transfers areinvestigated. It is found that Fe-As interaction is stronger than Fe-Ga interaction and Fe atoms prefer to be adsorbed onthe As-terminated surface. It is possible for the adsorbed Fe atoms to sit below the As-terminated surface resulting inan Fe-Ga-As mixed layer. The layer projected density states are calculated and compared with that of the clean surface.展开更多
A polycrystalline Voronoi aggregation with a free surface is applied as the representative volume element（RVE）of the nickel-based GH4169 superalloy.Considering the plastic deformation mechanism at the grain level an...A polycrystalline Voronoi aggregation with a free surface is applied as the representative volume element（RVE）of the nickel-based GH4169 superalloy.Considering the plastic deformation mechanism at the grain level and the Bauschinger effect,a crystal plasticity model reflecting the nonlinear kinematic hardening of crystal slipping system is applied.The microscopic inhomogeneous deformation during cyclic loading is calculated through numerical simulation of crystal plasticity.The deformation inhomogeneity on the free surface of the RVE under cyclic loading is described respectively by using the following parameters：standard deviation of the longitudinal strain in macro tensile direction,statistical average of first principal strains,and standard deviation of longitudinal displacement.The relationship between the fatigue cycle number and the evolution of inhomogeneous deformation of the material’s free surface is investigated.This research finds that：（1）The inhomogeneous deformation of the material free surface is significantly higher than that of the RVE inside;（2）the increases of the characterization parameters of inhomogeneous deformation on the free surface with cycles reflect the local maximum deformation of the RVE growing during cyclic loading;（3）these parameters can be used as criteria to assess and predict the low-cycle fatigue life rationally.展开更多
The harsh melt-spinning and annealing processes of high saturation magnetization nanocrystalline softmagnetic alloys are the biggest obstacles for their industrialization. Here, we proposed a novel strategy to enlarge...The harsh melt-spinning and annealing processes of high saturation magnetization nanocrystalline softmagnetic alloys are the biggest obstacles for their industrialization. Here, we proposed a novel strategy to enlarge the processing window by annealing the partially crystallized precursor ribbons via a heterostructured crystallization process. The heterostructured evolution of Fe_(84.75)Si_(2)B_(9)P_(3)_(C0.5)Cu_(0.75)(at.%)alloy ribbons with different spinning rate were studied in detail, to demonstrate the gradient nucleation and grain refinement mechanisms. The nanocrystalline alloys made with industrially acceptable spinning rate of 25-30 m/s and normal annealing process exhibit excellent magnetic properties and fine nanostructure. The small quenched-in crystals/clusters in the free surface of the low spinning rate ribbons will not grow to coarse grains, because of the competitive grain growth and shielding effect of metalloid elements rich interlayer with a high stability. Avoiding the precipitation of quenched-in coarse grains in precursor ribbons is thus a new criterion for the composition and process design, which is more convenient than the former one with respect to the homogenous crystallization mechanism, and enable us to produce high performance nanocrystalline soft-magnetic alloys. This strategy is also suitable for improving the compositional adjustability, impurity tolerance, and enlarging the window of melt temperature,which is an important reference for the future development of composition and process.展开更多
In the current study, two novel Knoevenagel condensation products of substituted napthofuran-2-carbaldehydes were designed, synthesized and characterized. In order to study the intermolecular interactions of titl...In the current study, two novel Knoevenagel condensation products of substituted napthofuran-2-carbaldehydes were designed, synthesized and characterized. In order to study the intermolecular interactions of title compounds, single crystals were grown by slow evaporation solution growth technique at </span><span style="font-family:Verdana;">r</span><span style="font-family:Verdana;">oom temperature and crystal structure has been determined by single crystal X-ray diffraction technique. Both the molecule</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> crystallize in the monoclinic centrosymmetric space group </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">2</span><sub><span style="font-size:12px;font-family:Verdana;">1</span></sub><span style="font-family:Verdana;">/</span><i><span style="font-family:Verdana;">c</span></i><span style="font-family:Verdana;"> with one molecule in the asymmetric unit. In compound </span><b><span style="font-family:Verdana;">[4] </span></b><span style="font-family:Verdana;">the molecules are connected via bifurcated C-H···O=C and C-H···N=C</span></span><span style="font-family:Verdana;"> </span><span style="font-family:""><span style="font-family:Verdana;">H-bonds and van der Waals interactions forming a layered structure, whereas in compound </span><b><span style="font-family:Verdana;">[5a</span></b></span><span style="font-family:Verdana;"><b>]</b></span><span style="font-family:""><span style="font-family:Verdana;"> the molecular conformation is stabilized via intramolecular C-H···O H-bond and molecule interacts with other molecule generated via 2</span><sub><span style="font-size:12px;font-family:Verdana;">1</span></sub><span style="font-family:Verdana;">-screw </span><i><span style="font-family:Verdana;">via</span></i><span style="font-family:Verdana;"> bifurcated C-H···O=</span></span><span style="font-family:Verdana;">C along with C-H···N=C H-bonds, which are interacting with nitro- of ot</span><span style="font-family:Verdana;">her molecule generated via same symmetry operation, forming bifurcated C-H···O-N </span><span style="font-family:Verdana;">H-bonds, which helps in formation of molecular sheet-like structure.</span><span style="font-family:Verdana;">Further, in order to understand the various type</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> and nature of intermolecular interactions</span><span style="font-family:Verdana;"> in the supramolecular structure Hirshfeld</span><span style="font-family:Verdana;"> surface analysis</span><span style="font-family:Verdana;"> and fingerprint plot analysis was carried out.展开更多
Flotation is a complex process that occurs in solid-liquid-gas multiphase systems,and its main factors include the minerals,separation medium,as well as various flotation reagents.The study of mineral properties and i...Flotation is a complex process that occurs in solid-liquid-gas multiphase systems,and its main factors include the minerals,separation medium,as well as various flotation reagents.The study of mineral properties and interactions with other components such as reagents and water lays the basic theoretical foundation for flotation.Density functional theory(DFT) calculations can qualitatively evaluate the exchange of matter and energy between the mineral system and the surroundings and quantitatively characterize these behaviors,which greatly expands the breadth and depth of flotation studies.This review systematically summarizes the advances of flotation research based on DFT studies,including the study of mineral crystal chemistry represented by the theory of lattice defects,mineral surface hydration such as hydrophilicity and hydrophobicity,surface regulation mechanism,and collecting mechanism based on surface adsorption theory.More significantly,it systematically elaborates different types of collectors according to their characteristics and emphatically explains the mechanism of some typical collectors in detail.展开更多
Multiplexing techniques have always been one of the important components of optical communication research.These techniques can transmit multiple signals in a shared information channel and can greatly increase the ma...Multiplexing techniques have always been one of the important components of optical communication research.These techniques can transmit multiple signals in a shared information channel and can greatly increase the maximum capacity of an information channel.The Dirac-vortex cavity is a type of photonic crystal surface emission system,and its characteristics of miniaturization and high stability make it very suitable for on-chip optical system.In this paper,we realized dual-channel emission of the Dirac-vortex cavity,which is achieved by modulating the size and phase of hexagonal holes in the hexagon lattice.The characteristics of dual-channel emission are investigated by numerical simulation,and the dual-channel emission rules are summarized.The double Diracvortex cavity model is not only explored for its multiplexing capability but also as an alternative scheme for the application of Dirac-vortex cavity in multiplex communication systems.展开更多
Manganese dissolution and the Jahn-Teller distortion represent the primary factors limiting the cycle life of spinel LiMn_(2)O_(4).In this study,Nb^(5+)-doped Li_(1.05)Mn_(2-x)Nb_(x)O_(4)(0≤x≤0.03)with truncated oct...Manganese dissolution and the Jahn-Teller distortion represent the primary factors limiting the cycle life of spinel LiMn_(2)O_(4).In this study,Nb^(5+)-doped Li_(1.05)Mn_(2-x)Nb_(x)O_(4)(0≤x≤0.03)with truncated octahedral morphology was successfully synthesized via a simple high-temperature solid-state method.Nb^(5+)doping not only enhanced the structural stability of LiMn_(2)O_(4) but also increased the Li^(+)diffusion rate.SEM analysis revealed that Nb^(5+)doping effectively suppressed(110)plane growth,thereby mitigating Mn dissolution.Simultaneously,TEM results indicated that a thinner cathode electrolyte interphase film was formed upon doping,which contributed to enhanced cycling stability.Further DFT calculations confirmed that Nb^(5+)doping improved the structural stability of LiMn_(2)O_(4) through a dual mechanism:reducing the occupancy of the Mn eg orbitals and strengthening the Mn-O bonding energy.On the other hand,Nb^(5+)doping expands the lattice,with CV and EIS tests showing increased Li+diffusion rates.PDOS calculations revealed a narrowed band gap,which improved the electronic conductivity,thereby endowing LiMn_(2)O_(4) with high-rate performance.Hence,Li_(1.05)Mn_(2-x)Nb_(x)O_(4) exhibits superior rate capability and extended cycle life.Specifically,Li_(1.05)Mn_(1.99)Nb_(0.01)O_(4) delivered an initial discharge capacity of 124.61 mAh/g with 88.43%capacity retention after 500 cycles at 1 C,and maintained 74.61 mAh/g even at 10 C.展开更多
We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectro...We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.展开更多
Myelin basic protein（MBP） is an essential structure involved in the generation of central nervous system（CNS）myelin.Myelin shape has been described as liquid crystal structure of biological membrane.The interactio...Myelin basic protein（MBP） is an essential structure involved in the generation of central nervous system（CNS）myelin.Myelin shape has been described as liquid crystal structure of biological membrane.The interactions of MBP with monolayers of different lipid compositions are responsible for the multi-lamellar structure and stability of myelin.In this paper,we have designed MBP-incorporated model lipid monolayers and studied the phase behavior of MBP adsorbed on the plasma membrane at the air/water interface by thermodynamic method and atomic force microscopy（AFM）.By analyzing the pressure–area（π–A） and pressure–time（π–T） isotherms,univariate linear regression equation was obtained.In addition,the elastic modulus,surface pressure increase,maximal insertion pressure,and synergy factor of monolayers were detected.These parameters can be used to modulate the monolayers binding of protein,and the results show that MBP has the strongest affinity for 1,2-dipalmitoyl-sn-glycero-3-phosphoserine（DPPS） monolayer,followed by DPPC/DPPS mixed and1,2-dipalmitoyl-sn-glycero-3-phospho-choline（DPPC） monolayers via electrostatic and hydrophobic interactions.AFM images of DPPS and DPPC/DPPS mixed monolayers in the presence of MBP（5 n M） show a phase separation texture at the surface pressure of 20 m N/m and the incorporation of MBP put into the DPPC monolayers has exerted a significant effect on the domain structure.MBP is not an integral membrane protein but,due to its positive charge,interacts with the lipid head groups and stabilizes the membranes.The interaction between MBP and phospholipid membrane to determine the nervous system of the disease has a good biophysical significance and medical value.展开更多
In this work,the shear model of metal melt flowing on vibration surface is established,and coupling effects of vibration and shear on the distribution of shear stress in melt and melt solidification microstructure are...In this work,the shear model of metal melt flowing on vibration surface is established,and coupling effects of vibration and shear on the distribution of shear stress in melt and melt solidification microstructure are analyzed.Calculation results show that the transition of melt from laminar flow to turbulent flow occurs earlier with increasing vibration frequency and vibration amplitude.In the laminar flow melt,shear stress in melt decreases with increasing vertical length,but it decreases firstly and then stabilizes with increasing flow length.In the turbulent flow melt,shear stress decreases firstly and then stabilizes with increasing vertical length,but it increases with increasing flow length.With the increase in vibration frequency and amplitude,shear stress along flow direction in laminar flow melt increases,while shear stresses along both flow direction and vertical direction in turbulent flow melt increase.Shear stress in melt decreases with increasing length along vertical direction.With the increase in flow length,shear stress decreases firstly and then stabilizes in laminar flow melt,while it increases in turbulent flow melt.With the increase in vibration frequency and amplitude,shear stress increases in laminar flow melt,while it stabilizes in turbulent flow melt.Based on theoretical calculation,the maximum shear stress in melt during vibration shear flow is always much lower than the yield strength of a-Al grain,so the shear stress induced by vibration shear flow cannot break columnar crystal,which agrees with the experiment result.So,the model can explain the shear constitutive relation of melt flow on vibration surface relatively well.展开更多
The finite-difference time-domain （FDTD） method is proposed for analyzing the surface acoustic wave （SAW） propagation in two-dimensional （2D） piezoelectric phononic crystals （PCs） at radio frequency （RF）, an...The finite-difference time-domain （FDTD） method is proposed for analyzing the surface acoustic wave （SAW） propagation in two-dimensional （2D） piezoelectric phononic crystals （PCs） at radio frequency （RF）, and also experiments are established to demonstrate its analysis result of the PCs＇ band gaps. The FDTD method takes the piezoelectric effect of PCs into account, in which periodic boundary conditions are used to decrease memory/time consumption and the perfectly matched layer boundary conditions are adopted as the SAW absorbers to attenuate artificial reflections. Two SAW delay lines are established with/without piezoelectric PCs located between interdigital transducers. By removing several echoes with window gating function in time domain, delay lines transmission function is achieved. The PCs＇ transmission functions and band gaps are obtained by comparing them in these two delay lines. When Aluminum/128°YX-LiNbO3 is adopted as scatter and substrate material, the PCs＇ band gap is calculated by this FDTD method and COMSOL respectively. Results show that computational results of FDTD agree well with experimental results and are better than that of COMSOL.展开更多
基金funded by National Key R&D Program of China(Grant Nos.2024YFB3612200,2023YFB3609601,2022YFB3604300,2022YFB2802801,2022YFB3604802)Natural Science Foundation of China(Grant Nos.U24A20300,62174174,62274177,62275263,62325406,62374172,62304242,62304240,62404241)+4 种基金Youth Innovation Promotion Association of CAS(Grant Nos.2022323 and 2022324)Key R&D Program of Jiangsu Province(Grant No.BE2023018-2)Basic Research Program of Jiangsu(Grant No.BK20240126)Suzhou Science and Technology Program(Grant Nos.SYC2022089,ZXL2024379,and ZXL2024376)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022A1515110482 and 2022A1515110004).
文摘Photonic crystal surface emitting lasers(PCSELs)utilize the Bragg diffraction of two-dimensional photonic crystals to achieve a single-mode output with a high power and a small divergence angle,and has recently attracted much attention^([1−3]).In 2023,Kyoto University reported GaAs-based 945 nm PCSELs with a continuous-wave(CW)single-mode output power of exceeding 50 W,and a narrow beam divergence angle of 0.05°,demonstrating a brightness of 1 GW·cm^(−2)·sr^(−1),which rivals those of the existing bulky lasers^([4]).
基金The project is supported by the National Natural Science Foundation of China
文摘So far, the diffracted SAW field generated by an IDT with finite aperture on piezoelectric crystal surfaces is usually analyzed phenomenologically with the angular spectrum theory. A major approximation of this theory is to ignore the vector nature of the field by assuming that the wave field can be represented by a scalar as in optics. In this paper, a rigorous vector field theory of the surface excitation of elastic wave field in piezoelectric crystal developed by the authors is used to evaluate the SAW diffraction field adepately and precisely. As an example, numerical results for YZ-LiNbO3 are presented and compared with those obtained form the angular spectrum theory.
基金financialy supported by the National Key R&D Program of China(Grant No.2018YFB0905400)the National Natural Science Foundation of China(Grant Nos.22075331,51702376)+2 种基金the Fundamental Research Funds for the Central Universities(19lgzd02)the Guangdong Pearl River Talents Plan(2019QN01L117)the National Thousand Youth Talents Project of the Chinese Government
文摘For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anticorrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(<40 mV).Even at 6 mA cm^(−2) and 3 mA h cm^(−2),it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO_(2) cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.51401210 and51271186)the National High Technology Research and Development Program of China(No.2014AA041701)
文摘A geometric analysis technique for crystal growth and microstructure development in single-crystal welds had been previously developed.And the effect of welding conditions on the tendency of stray grains formation during solidification was researched.In the present work,these analytical methods were further extended.Combined with an original vectorization method,a 3D Rosenthal solution was used to determine thermal conditions of the welds.Afterward,the dendrite growth orientation,the dendrite growth velocity and the thermal gradient along dendrite direction were calculated and lively plotted.Finally,the tendency of stray grains formation in the solidification front was forecasted and its distribution was presented with a 3D plot.The results indicate that substrate orientation has some impacts on the crystal growth pattern,dendrite growth velocity,distribution of thermal gradient and stray grain.Based on the research methods proposed in this work,any substrate crystallographic orientation can be studied,and predicted stray grains distribution can be visualized.
基金supported by the National Natural Science Foundation of China (Nos. 51271186 and 51001103)
文摘Effects of Re on the formation of surface eutectics have been investigated by using Ni-base single crystal superalloys with different Re additions. It was found that Re promotes the segregation of Al and Ta to the eutectic melt, leading to an increase of the surface and internal eutectics. In addition, the addition of Re also increased the freezing range, the local solidification time, and the permeability of the dendritic network within the mushy zone. These factors ultimately promoted the outflow of the interdendritic residual liquid with the action of solidification shrinkage, and led to the formation of more surface eutectics. In contrast, the addition of Re had no obvious influence on the surface eutectic microstructures.
基金Supported by the financial support of Fundamental Research Funds for the Central Universities(3207045420)Jiangsu Ainaji Neoenergy Science&Technology Co.,Ltd.(8507040091)
文摘One new polymer [Co（L）（H2O）2]n（1） was synthesized by 4-（ethoxycarbonyl）-5-methyl-1H-1,2,3-triazole-1-carboxylic acid（Emtc） under the in situ solvent thermal reaction（H2L = 1-（carboxymethyl）-5-methyl-1H-1,2,3-triazole-4-carboxylic acid）. The title complex performs a wave-like 2D framework and the ligand H2L demonstrates the coordination mode as μ4-η-2：η-1η-1：η-1. The crystal structure has been established by single-crystal X-ray diffraction, and characterized by FT-IR. Fluorescent property was investigated in this work. Hirshfeld surface analysis has also been carried out on 1, and obvious main intermolecular interactions are observed.
基金supported by the National Natural Science Foundation of China(No.20801012)New Energy Technology Co.Ltd.of Ai Naji of Jiangsu Province(No.8507040091)
文摘The crystal structure of one novel Mn（II） complex, [Mn（pmta）_3]_2[Mn（H_2O）_6]·4H_2O（1）, is reported（Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid）. In the title compound, the asymmetric unit consists of a [Mn（pmta_）3]ˉ anion, half [Mn（H_2O）_6]^（2＋） counter cation and two lattice H_2O molecules, and the intra- and intermolecular hydrogen bonds connect the complex into a supramolecular structure. The liquid-state fluorescence spectra of complex 1 have been determined. Hirshfeld surface analysis was also studied. The main intermolecular interactions in the complex are O···H and H···H contacts.
基金financially supported by the National Natural Science Foundation of China (NSFC) under grant Nos. 51401210 and 51271186the National High Technology Research and Development Program (863 Program) of China under grant No. 2014AA041701
文摘A vectorization analysis technique for crystal growth and microstructure development in single-crystal weld was developed in our previous work. Based on the vectorization method, crystal growth and stray grain distribution in laser surface remelting of single crystal superalloy CMSX-4 were investigated in com- bination of simulations with experimental observations. The energy distribution of laser was taken into consideration in this research. The experimental results demonstrate that the simulation model applies well in the prediction of dendrite growth direction. Moreover, the prediction of stray grain distribution works well except for the region of dendrites growing along the [100] direction.
基金the financial support from the Swedish Research Council(VR)(Public,Sweden)the Swedish Foundation for Strategic Research(SSF)(Non-Profit,Sweden)。
文摘Alkanes are present in the atmosphere,commonly in the form of aerosols,and can thus interact with water droplets,leading to the formation of new interfaces.Yet,in the study of these interactions,traditional experimental methods often rely on the presence of sample containers,which can interfere with the observations.Acoustic levitation is a technique which allows the manipulation of samples in the microliter regime in a contact-free manner.Hence,interfacial phenomena can be studied without the presence of external surfaces,mimicking atmospheric conditions.Herein,we acoustically levitated a droplet of water in contact with a droplet of hexadecane and observed interfacial crystallization at the hexadecane/water interface that propagated to the entire droplet of hexadecane.It was found that the crystallization occurred up to 3 K above the melting temperature of hexadecane,and at a relative humidity below 30%.Moreover,the volume ratio between water and hexadecane influenced the fraction of crystallized surface area;for a hexadecane:water ratio above 1:2 full surface crystallization occurred.Combining acoustic levitation with Raman spectroscopy allowed the characterization of the phase transition in real time,demonstrating the existence of a solid crystal of alkane upon water evaporation.This study provides insights into the process of interfacial crystallization of hexadecane and demonstrates the suitability of acoustic levitation to study contact-free interfacial phenomena between two immiscible liquids.
文摘The adsorption of one monolayer Fe atoms on an ideal GaAs (100) surface is studied by using the self-consistent tight-binding linear muffin-tin orbital method. The Fe adatom chemisorption on Ga- and As-terminatedsurface are considered separately. A monolayer of S atoms is used to saturate the dangling bonds on one of the supercellsurfaces. Energies of adsorption systems of an Fe atom on different sites are calculated, and the charge transfers areinvestigated. It is found that Fe-As interaction is stronger than Fe-Ga interaction and Fe atoms prefer to be adsorbed onthe As-terminated surface. It is possible for the adsorbed Fe atoms to sit below the As-terminated surface resulting inan Fe-Ga-As mixed layer. The layer projected density states are calculated and compared with that of the clean surface.
基金supported by the National Natural Scientific Foundation of China (Fund Nos. 11472085 and 11632007)the Guangxi Science Research and Technology Development Project (Fund No. GKH1599005-2-5)the Innovation Project of Guangxi Graduate Education (Fund no. YCBZ2015008)
文摘A polycrystalline Voronoi aggregation with a free surface is applied as the representative volume element（RVE）of the nickel-based GH4169 superalloy.Considering the plastic deformation mechanism at the grain level and the Bauschinger effect,a crystal plasticity model reflecting the nonlinear kinematic hardening of crystal slipping system is applied.The microscopic inhomogeneous deformation during cyclic loading is calculated through numerical simulation of crystal plasticity.The deformation inhomogeneity on the free surface of the RVE under cyclic loading is described respectively by using the following parameters：standard deviation of the longitudinal strain in macro tensile direction,statistical average of first principal strains,and standard deviation of longitudinal displacement.The relationship between the fatigue cycle number and the evolution of inhomogeneous deformation of the material’s free surface is investigated.This research finds that：（1）The inhomogeneous deformation of the material free surface is significantly higher than that of the RVE inside;（2）the increases of the characterization parameters of inhomogeneous deformation on the free surface with cycles reflect the local maximum deformation of the RVE growing during cyclic loading;（3）these parameters can be used as criteria to assess and predict the low-cycle fatigue life rationally.
基金supported financially by the National Key Research and Development Program of China (No.2016YFB0300501)the National Natural Science Foundation of China (Nos.51771159,51774217,51801224,51971186)+3 种基金the Zhejiang Provincial Natural Science Foundation (No.LQ18E010006)the Ningbo Major Special Projects of the Plan"Science and Technology Innovation 2025"(No.2018B10084)financial support from general research fund (GRF)the Hong Kong Government,through the general research fund (GRF,Nos.CityU11200719,CityU11213118 and CityU11209317)。
文摘The harsh melt-spinning and annealing processes of high saturation magnetization nanocrystalline softmagnetic alloys are the biggest obstacles for their industrialization. Here, we proposed a novel strategy to enlarge the processing window by annealing the partially crystallized precursor ribbons via a heterostructured crystallization process. The heterostructured evolution of Fe_(84.75)Si_(2)B_(9)P_(3)_(C0.5)Cu_(0.75)(at.%)alloy ribbons with different spinning rate were studied in detail, to demonstrate the gradient nucleation and grain refinement mechanisms. The nanocrystalline alloys made with industrially acceptable spinning rate of 25-30 m/s and normal annealing process exhibit excellent magnetic properties and fine nanostructure. The small quenched-in crystals/clusters in the free surface of the low spinning rate ribbons will not grow to coarse grains, because of the competitive grain growth and shielding effect of metalloid elements rich interlayer with a high stability. Avoiding the precipitation of quenched-in coarse grains in precursor ribbons is thus a new criterion for the composition and process design, which is more convenient than the former one with respect to the homogenous crystallization mechanism, and enable us to produce high performance nanocrystalline soft-magnetic alloys. This strategy is also suitable for improving the compositional adjustability, impurity tolerance, and enlarging the window of melt temperature,which is an important reference for the future development of composition and process.
文摘In the current study, two novel Knoevenagel condensation products of substituted napthofuran-2-carbaldehydes were designed, synthesized and characterized. In order to study the intermolecular interactions of title compounds, single crystals were grown by slow evaporation solution growth technique at </span><span style="font-family:Verdana;">r</span><span style="font-family:Verdana;">oom temperature and crystal structure has been determined by single crystal X-ray diffraction technique. Both the molecule</span><span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> crystallize in the monoclinic centrosymmetric space group </span><i><span style="font-family:Verdana;">P</span></i><span style="font-family:Verdana;">2</span><sub><span style="font-size:12px;font-family:Verdana;">1</span></sub><span style="font-family:Verdana;">/</span><i><span style="font-family:Verdana;">c</span></i><span style="font-family:Verdana;"> with one molecule in the asymmetric unit. In compound </span><b><span style="font-family:Verdana;">[4] </span></b><span style="font-family:Verdana;">the molecules are connected via bifurcated C-H···O=C and C-H···N=C</span></span><span style="font-family:Verdana;"> </span><span style="font-family:""><span style="font-family:Verdana;">H-bonds and van der Waals interactions forming a layered structure, whereas in compound </span><b><span style="font-family:Verdana;">[5a</span></b></span><span style="font-family:Verdana;"><b>]</b></span><span style="font-family:""><span style="font-family:Verdana;"> the molecular conformation is stabilized via intramolecular C-H···O H-bond and molecule interacts with other molecule generated via 2</span><sub><span style="font-size:12px;font-family:Verdana;">1</span></sub><span style="font-family:Verdana;">-screw </span><i><span style="font-family:Verdana;">via</span></i><span style="font-family:Verdana;"> bifurcated C-H···O=</span></span><span style="font-family:Verdana;">C along with C-H···N=C H-bonds, which are interacting with nitro- of ot</span><span style="font-family:Verdana;">her molecule generated via same symmetry operation, forming bifurcated C-H···O-N </span><span style="font-family:Verdana;">H-bonds, which helps in formation of molecular sheet-like structure.</span><span style="font-family:Verdana;">Further, in order to understand the various type</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> and nature of intermolecular interactions</span><span style="font-family:Verdana;"> in the supramolecular structure Hirshfeld</span><span style="font-family:Verdana;"> surface analysis</span><span style="font-family:Verdana;"> and fingerprint plot analysis was carried out.
基金financially supported by the Natural Science Foundation of China under grants: U20A20269, 51874106, and 51574092。
文摘Flotation is a complex process that occurs in solid-liquid-gas multiphase systems,and its main factors include the minerals,separation medium,as well as various flotation reagents.The study of mineral properties and interactions with other components such as reagents and water lays the basic theoretical foundation for flotation.Density functional theory(DFT) calculations can qualitatively evaluate the exchange of matter and energy between the mineral system and the surroundings and quantitatively characterize these behaviors,which greatly expands the breadth and depth of flotation studies.This review systematically summarizes the advances of flotation research based on DFT studies,including the study of mineral crystal chemistry represented by the theory of lattice defects,mineral surface hydration such as hydrophilicity and hydrophobicity,surface regulation mechanism,and collecting mechanism based on surface adsorption theory.More significantly,it systematically elaborates different types of collectors according to their characteristics and emphatically explains the mechanism of some typical collectors in detail.
基金National Natural Science Foundation of China(12404423,62375007,62405012)Natural Science Foundation of Beijing Municipality(1232024)Applied Basic Research Fund of School of Physics and Optoelectronic Engineering,Beijing University of Technology(ABRFSPOE03).
文摘Multiplexing techniques have always been one of the important components of optical communication research.These techniques can transmit multiple signals in a shared information channel and can greatly increase the maximum capacity of an information channel.The Dirac-vortex cavity is a type of photonic crystal surface emission system,and its characteristics of miniaturization and high stability make it very suitable for on-chip optical system.In this paper,we realized dual-channel emission of the Dirac-vortex cavity,which is achieved by modulating the size and phase of hexagonal holes in the hexagon lattice.The characteristics of dual-channel emission are investigated by numerical simulation,and the dual-channel emission rules are summarized.The double Diracvortex cavity model is not only explored for its multiplexing capability but also as an alternative scheme for the application of Dirac-vortex cavity in multiplex communication systems.
基金This work was carried out in part using computing resources at the High Performance Computing Center of Central South University.
文摘Manganese dissolution and the Jahn-Teller distortion represent the primary factors limiting the cycle life of spinel LiMn_(2)O_(4).In this study,Nb^(5+)-doped Li_(1.05)Mn_(2-x)Nb_(x)O_(4)(0≤x≤0.03)with truncated octahedral morphology was successfully synthesized via a simple high-temperature solid-state method.Nb^(5+)doping not only enhanced the structural stability of LiMn_(2)O_(4) but also increased the Li^(+)diffusion rate.SEM analysis revealed that Nb^(5+)doping effectively suppressed(110)plane growth,thereby mitigating Mn dissolution.Simultaneously,TEM results indicated that a thinner cathode electrolyte interphase film was formed upon doping,which contributed to enhanced cycling stability.Further DFT calculations confirmed that Nb^(5+)doping improved the structural stability of LiMn_(2)O_(4) through a dual mechanism:reducing the occupancy of the Mn eg orbitals and strengthening the Mn-O bonding energy.On the other hand,Nb^(5+)doping expands the lattice,with CV and EIS tests showing increased Li+diffusion rates.PDOS calculations revealed a narrowed band gap,which improved the electronic conductivity,thereby endowing LiMn_(2)O_(4) with high-rate performance.Hence,Li_(1.05)Mn_(2-x)Nb_(x)O_(4) exhibits superior rate capability and extended cycle life.Specifically,Li_(1.05)Mn_(1.99)Nb_(0.01)O_(4) delivered an initial discharge capacity of 124.61 mAh/g with 88.43%capacity retention after 500 cycles at 1 C,and maintained 74.61 mAh/g even at 10 C.
文摘We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21402114 and 11544009)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2016JM2010)+1 种基金the Fundamental Research Funds for the Central Universities of China(Grant No.GK201604004)the National University Science and Technology Innovation Project of China(Grant Nos.201610718014 and cx16018)
文摘Myelin basic protein（MBP） is an essential structure involved in the generation of central nervous system（CNS）myelin.Myelin shape has been described as liquid crystal structure of biological membrane.The interactions of MBP with monolayers of different lipid compositions are responsible for the multi-lamellar structure and stability of myelin.In this paper,we have designed MBP-incorporated model lipid monolayers and studied the phase behavior of MBP adsorbed on the plasma membrane at the air/water interface by thermodynamic method and atomic force microscopy（AFM）.By analyzing the pressure–area（π–A） and pressure–time（π–T） isotherms,univariate linear regression equation was obtained.In addition,the elastic modulus,surface pressure increase,maximal insertion pressure,and synergy factor of monolayers were detected.These parameters can be used to modulate the monolayers binding of protein,and the results show that MBP has the strongest affinity for 1,2-dipalmitoyl-sn-glycero-3-phosphoserine（DPPS） monolayer,followed by DPPC/DPPS mixed and1,2-dipalmitoyl-sn-glycero-3-phospho-choline（DPPC） monolayers via electrostatic and hydrophobic interactions.AFM images of DPPS and DPPC/DPPS mixed monolayers in the presence of MBP（5 n M） show a phase separation texture at the surface pressure of 20 m N/m and the incorporation of MBP put into the DPPC monolayers has exerted a significant effect on the domain structure.MBP is not an integral membrane protein but,due to its positive charge,interacts with the lipid head groups and stabilizes the membranes.The interaction between MBP and phospholipid membrane to determine the nervous system of the disease has a good biophysical significance and medical value.
基金supported financially by the National Natural Science Foundation of China (Nos. 51474063, 51674077)the Fundamental Research Funds for the Central Universities (No. N150204016)
文摘In this work,the shear model of metal melt flowing on vibration surface is established,and coupling effects of vibration and shear on the distribution of shear stress in melt and melt solidification microstructure are analyzed.Calculation results show that the transition of melt from laminar flow to turbulent flow occurs earlier with increasing vibration frequency and vibration amplitude.In the laminar flow melt,shear stress in melt decreases with increasing vertical length,but it decreases firstly and then stabilizes with increasing flow length.In the turbulent flow melt,shear stress decreases firstly and then stabilizes with increasing vertical length,but it increases with increasing flow length.With the increase in vibration frequency and amplitude,shear stress along flow direction in laminar flow melt increases,while shear stresses along both flow direction and vertical direction in turbulent flow melt increase.Shear stress in melt decreases with increasing length along vertical direction.With the increase in flow length,shear stress decreases firstly and then stabilizes in laminar flow melt,while it increases in turbulent flow melt.With the increase in vibration frequency and amplitude,shear stress increases in laminar flow melt,while it stabilizes in turbulent flow melt.Based on theoretical calculation,the maximum shear stress in melt during vibration shear flow is always much lower than the yield strength of a-Al grain,so the shear stress induced by vibration shear flow cannot break columnar crystal,which agrees with the experiment result.So,the model can explain the shear constitutive relation of melt flow on vibration surface relatively well.
基金supported by the National Natural Science Foundation of China(11174318,11304346,61106081)Chinese Postdoctoral Science Foundation(2011M501204,2013T60718)+2 种基金National High Technology Research and Development Program(863 Program)(SS2013AA041103)Beijing Municipal Science and Technology Commission Project(Z141100003814016)the Fundamental Research Funds for the Central Universities(HUST:2013QN038)
文摘The finite-difference time-domain （FDTD） method is proposed for analyzing the surface acoustic wave （SAW） propagation in two-dimensional （2D） piezoelectric phononic crystals （PCs） at radio frequency （RF）, and also experiments are established to demonstrate its analysis result of the PCs＇ band gaps. The FDTD method takes the piezoelectric effect of PCs into account, in which periodic boundary conditions are used to decrease memory/time consumption and the perfectly matched layer boundary conditions are adopted as the SAW absorbers to attenuate artificial reflections. Two SAW delay lines are established with/without piezoelectric PCs located between interdigital transducers. By removing several echoes with window gating function in time domain, delay lines transmission function is achieved. The PCs＇ transmission functions and band gaps are obtained by comparing them in these two delay lines. When Aluminum/128°YX-LiNbO3 is adopted as scatter and substrate material, the PCs＇ band gap is calculated by this FDTD method and COMSOL respectively. Results show that computational results of FDTD agree well with experimental results and are better than that of COMSOL.
