Let Ln be the hexagonal chain graph, Fn be the hexacyclic system graph and Mn be the MSbius hexacyclic system graph. Derflinger and Sofer gave the spectra of Ln and Fn by using group theoretical method. Later, Gutman ...Let Ln be the hexagonal chain graph, Fn be the hexacyclic system graph and Mn be the MSbius hexacyclic system graph. Derflinger and Sofer gave the spectra of Ln and Fn by using group theoretical method. Later, Gutman gave the spectra of them using a polynomial result due to Godsil and McKay. In this paper, we give a simple and direct method to determine the characteristic polynomial and spectra of Fn and Ln. By the method, we give the characteristic polynomial and spectrum of Mn that is new. Additionally, the exact values of total π-electron energy and the nullities of Ln, Fn and Mn are obtained, and the bounds for the energy of Ln and Mn are also considered.展开更多
A formula was proved for computing the zeroth-order general Randic index of a hexagonal system to explore the correlation between the zeroth-order general Randic index and the π-electronic energy of a hexagonal syste...A formula was proved for computing the zeroth-order general Randic index of a hexagonal system to explore the correlation between the zeroth-order general Randic index and the π-electronic energy of a hexagonal system.As a consequence,the extremal hexagonal systems with minimum or maximum zeroth-order general Randic index were completely characterized.Moreover,by using the least-square fit method and regression analysis,a new and close relation was found between the zeroth-order general Randic index and the π-electronic energy of a hexagonal system.So the zeroth-order general Randic index is a good measure of the π-electronic energies for benzenoid hydrocarbons.展开更多
The A_(α)-matrix of a graph G is defined as A_(α)(G)=αD(G)+(1-α)A(G)(α∈[0,1]),given by Nikiforov in 2017,where A(G) and D(G) are,respectively,the adjacency matrix and the degree matrix of graph G.Let F_(n)and M_...The A_(α)-matrix of a graph G is defined as A_(α)(G)=αD(G)+(1-α)A(G)(α∈[0,1]),given by Nikiforov in 2017,where A(G) and D(G) are,respectively,the adjacency matrix and the degree matrix of graph G.Let F_(n)and M_(n)be hexacyclic system graph and Möbius hexacyclic system graph,respectively.In this paper,according to the determinant and the eigenvalues of a circulant matrix,we firstly present Aα-characteristic polynomial and Aα-spectrum of F_(n)(resp.,M_(n)).Furthermore,we obtain the upper bound of the Aα-energy of F_(n)(resp.,M_(n)).展开更多
Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown tha...Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown that this structure gives it exceptional physical properties that exceed those of cubic diamond,making it highly promising for groundbreaking applications in superhard cutting tools,wide-bandgap semiconductor devices,and materials for extreme environments.As a result,the controllable synthesis of hexagonal diamond has emerged as a cutting-edge research focus in materials science.This review briefly outlines the progress in this area,with a focus on the mechanisms governing its key synthesis conditions,its intrinsic physical properties,and its potential applications in various fields.展开更多
Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and...Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and protective materials.Ion irradiation is frequently employed to create V_(B)^(-)spin defects in hBN.However,the optimal ion irradiation parameters remain unclear,even though they play a crucial role in determining the depth and density of the defects,which in turn affect sensing sensitivity.In this work,we optimize the carbon ion irradiation parameters for creating V_(B)^(-)spin defects by varying the irradiation dose and the incident angle.For 30 keV carbon ion irradiation,the optimal irradiation dose to create a V_(B)^(-)ensemble is determined to be 4×10^(13)ions/cm^(2),and both continuous and pulsed optically detected magnetic resonance measurements are used to estimate the magnetic sensitivity and spin coherence properties.Moreover,the incident angle of energetic ions is found to influence both the depth and density distributions of the V_(B)^(-)ensemble,a factor that is often overlooked.These results pave the way for improving the performance of quantum sensors based on hBN spin defects by optimizing the irradiation parameters.展开更多
It is significant to process textures with special functions similar to animal surfaces based on bionics and improve the friction stability and contact comfort of contact surfaces for the surface texture design of tac...It is significant to process textures with special functions similar to animal surfaces based on bionics and improve the friction stability and contact comfort of contact surfaces for the surface texture design of tactile products.In this paper,a bionic hexagonal micro-convex texture was prepared on an acrylic surface by laser processing.The friction mechanism of a finger touching the bionic hexagonal micro-convex texture under different touch speeds and pressures,and the effect of the height of the texture on tactile perception were investigated by finite element,subjective evaluation,friction,and EEG tests.The results showed that the deformation friction was the main friction component when the finger touched the bionic hexagonal texture,and the slipperiness and friction factor showed a significant negative correlation.As the touch speed decreased or the touch force increased,the hysteresis friction of the fingers as well as the interlocking friction increased,and the slipperiness perception decreased.The bionic hexagonal texture with higher convexity caused a higher friction factor,lower slipperiness perception,and lower P300 peak.Hexagonal textures with lower convexity,lower friction factor,and higher slipperiness perception required greater brain attentional resources and intensity of tactile information processing during tactile perception.展开更多
Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 7...Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 77 K over a broad strain rate range from 0.001 to 1 s^(-1).A critical strain rate of approximately 0.5 s^(-1)was identified,above which ductility exhibits a pronounced reduction,whereas below this threshold,ductility remains relatively stable.Through comprehensive analyses of strain evolution,deformed microstructure,and fracture morphology,this behavior is attributed to severe localized adiabatic heating resulting from inhomogeneous deformation,rather than conventional twin or shear mechanisms.展开更多
In this study,we employed molecular dynamics simulations to investigate the interfacial thermal conductance(ITC)and phonon transport of heterostructures composed of graphene(GE)and quasi-hexagonal phase fullerene(qHPC...In this study,we employed molecular dynamics simulations to investigate the interfacial thermal conductance(ITC)and phonon transport of heterostructures composed of graphene(GE)and quasi-hexagonal phase fullerene(qHPC60).We examined the effects of size,interface interaction coefficients,and thermal equilibrium time on the ITC of the GE/qHPC60 heterostructure.展开更多
Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin ...Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.展开更多
Enhancing the electrocatalytic activity of the electrode materials,specifically oxygen reduction reaction(ORR),at lower operating temperatures(<600℃)is the prime rank to realize the commercialization of solid oxid...Enhancing the electrocatalytic activity of the electrode materials,specifically oxygen reduction reaction(ORR),at lower operating temperatures(<600℃)is the prime rank to realize the commercialization of solid oxide fuel cells(SOFCs)research.Herein,a new hexagonal structure-based cathode material was developed with the co-doping of Gd_(2)O_(3)and Cr_(2)O_(3)of parent SrFe_(12)O_(19)oxide,respectively.At 550-475℃,Sr_(0.90)Gd_(0.10)Fe_(11.90)Cr_(0.10)O_(19)(SFO-10)cathode sample leading to the large peak power density(PPD)of 395 mW/cm^(2),has appropriate surface oxygen defects(O_(β))up to 17%,as verified by X-ray photoelectron microscopy(XPS).Theoretical calculations reveal that the co-doping of Gd and Cr oxides creates lattice disorder at the hexagonal lattice,which decreases the energy barrier for ion transport and enhances the electrocatalytic characteristics of ORR.Consequently,the SFO-10 cathode shows a favorable ORR activity with the least lower polarization resistance(ASR)at 550℃with gadolinium-doped ceria(GDC)electrolyte.This work provides a self-assembled single-phase hexagonal cathode to accelerate the lowtemperature hindrance of SOFC technology.展开更多
Track reconstruction algorithms are critical for polarization measurements.Convolutional neural networks(CNNs)are a promising alternative to traditional moment-based track reconstruction approaches.However,the hexagon...Track reconstruction algorithms are critical for polarization measurements.Convolutional neural networks(CNNs)are a promising alternative to traditional moment-based track reconstruction approaches.However,the hexagonal grid track images obtained using gas pixel detectors(GPDs)for better anisotropy do not match the classical rectangle-based CNN,and converting the track images from hexagonal to square results in a loss of information.We developed a new hexagonal CNN algorithm for track reconstruction and polarization estimation in X-ray polarimeters,which was used to extract the emission angles and absorption points from photoelectron track images and predict the uncer-tainty of the predicted emission angles.The simulated data from the PolarLight test were used to train and test the hexagonal CNN models.For individual energies,the hexagonal CNN algorithm produced 15%-30%improvements in the modulation factor compared to the moment analysis method for 100%polarized data,and its performance was comparable to that of the rectangle-based CNN algorithm that was recently developed by the Imaging X-ray Polarimetry Explorer team,but at a lower computational and storage cost for preprocessing.展开更多
Topological physics has evolved from its initial focus on fermionic systems to the exploration of bosonic systems,particularly phononic excitations in crystalline materials.Two-dimensional(2D)topological phonons emerg...Topological physics has evolved from its initial focus on fermionic systems to the exploration of bosonic systems,particularly phononic excitations in crystalline materials.Two-dimensional(2D)topological phonons emerge as promising candidates for future technological applications.Currently,experimental verification of 2D topological phonons has remained exclusively limited to graphene,a constraint that hinders their applications in phononic devices.Here,we report experimental evidence of topological phonons in monolayer hexagonal boron nitride using advanced high-resolution electron energy loss spectroscopy.Our high-precision measurements explicitly demonstrate two topological nodal rings in monolayer hexagonal boron nitride,protected by mirror symmetry,expanding the paradigm of 2D topological phonons beyond graphene.This research not only deepens fundamental understanding of 2D topological phonons,but also establishes a phononic device platform based on wide-bandgap insulators,crucial for advancements in electronics and photonics applications.展开更多
In this paper,we propose a numerical calculation model of the multigroup neutron diffusion equation in 3D hexagonal geometry using the nodal Green's function method and verified it.We obtained one-dimensional tran...In this paper,we propose a numerical calculation model of the multigroup neutron diffusion equation in 3D hexagonal geometry using the nodal Green's function method and verified it.We obtained one-dimensional transverse integrated equations using the transverse integration procedure over 3D hexagonal geometry and denoted the solutions as a nodal Green's functions under the Neumann boundary condition.By applying a quadratic polynomial expansion of the transverse-averaged quantities,we derived the net neutron current coupling equation,equation for the expansion coefficients of the transverse-averaged neutron flux,and formulas for the coefficient matrix of these equations.We formulated the closed system of equations in correspondence with the boundary conditions.The proposed model was tested by comparing it with the benchmark for the VVER-440 reactor,and the numerical results were in good agreement with the reference solutions.展开更多
In this paper,the mechanical response of a one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)thin film is analyzed under electric and temperature loads.Based on the Euler-Bernoulli beam theory,a theoretical ...In this paper,the mechanical response of a one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)thin film is analyzed under electric and temperature loads.Based on the Euler-Bernoulli beam theory,a theoretical model is proposed,resulting in coupled governing integral equations that account for interfacial normal and shear stresses.To numerically solve these integral equations,an expansion method using orthogonal Chebyshev polynomials is employed.The results provide insights into the interfacial stresses,axial force,as well as axial and vertical deformations of the PQC film.Additionally,fracture criteria,including stress intensity factors,mode angles,and the J-integral,are evaluated.The solution is compared with the membrane theory,neglecting the normal stress and bending deformation.Finally,the effects of stiffness and aspect ratio on the PQC film are thoroughly discussed.This study serves as a valuable guide for controlling the mechanical response and conducting safety assessments of PQC film systems.展开更多
Silicon carbide(SiC)junction barrier Schottky(JBS)diode has been widely used in power electronic systems due to its excellent physical characteristics and electrical performance,and the structural design of its source...Silicon carbide(SiC)junction barrier Schottky(JBS)diode has been widely used in power electronic systems due to its excellent physical characteristics and electrical performance,and the structural design of its source area has a particularly significant impact on the performance.This study provides a comparative analysis of the SiC JBS diode performance of different hexagonal structures,aiming to provide theoretical support and practical guidance for the optimization of JBS diode performance.Through theoretical derivation,experimental verification and data processing,the paper deeply analyzes the influence of hexagonal structure on JBS diode current distribution and breakdown voltage,and proposes a targeted optimization strategy.展开更多
Despite advances in photocatalytic half-reduction reactions,challenges remain in effectively utilizing electron-hole pairs in concurrent redox processes.The present study involved the construction of a p-n junction Co...Despite advances in photocatalytic half-reduction reactions,challenges remain in effectively utilizing electron-hole pairs in concurrent redox processes.The present study involved the construction of a p-n junction Co_(3)O_(4)/Zn_(3)In_(2)S_(6)(CoZ)hybrid with a complementary band edge potential.The photocatalyst formed by the 2D assembled-nanostructure portrayed an optimal yield of 13.8(H_(2))and 13.1(benzaldehyde)mmol g^(-1)h^(-1)when exposed to light(λ>420 nm),surpassing 1%Pt-added ZIS(12.4(H_(2))and 10.71(benzaldehyde)mmol g^(-1)h^(-1)).Around 95%of the electron-hole utilization rate was achieved.The solar-to-hydrogen(STH)and apparent quantum yield(AQY)values of 0.466%and 4.96%(420nm)achieved by this system in the absence of sacrificial agents exceeded those of previous works.The exceptional performance was mostly ascribed to the synergistic development of adjoining p-n heterojunctions and the built-in electric field for effective charge separation.Moreover,scavenger studies elucidated the intricate mechanistic enigma of the dual-redox process,in which benzaldehyde was produced via O-H activation and subsequent C-H cleavage of benzyl alcohol over CoZ hybrids.Furthermore,the widespread use of the optimal 1-CoZ composites was confirmed in multiple photoredox systems.This work presents an innovative perspective on the construction of dual-functioning p-n heterojunctions for practical photoredox applications.展开更多
The anti-forcing number of a perfect matching M of a graph G is the minimal number of edges not in M whose removal makes M a unique perfect matching of the resulting graph. The anti-forcing spectrum of G is the set of...The anti-forcing number of a perfect matching M of a graph G is the minimal number of edges not in M whose removal makes M a unique perfect matching of the resulting graph. The anti-forcing spectrum of G is the set of anti-forcing numbers over all perfect matchings of G. In this paper, we prove that the anti-forcing spectrum of any cata-condensed hexagonal system is continuous, that is, it is a finite set of consecutive integers.展开更多
Based on the reported physical parameters for hexagonal system solids,we have calculated the effects of anisotropy on polarization of plane P-wave propagation.Herein we report the results of calculations and the newly...Based on the reported physical parameters for hexagonal system solids,we have calculated the effects of anisotropy on polarization of plane P-wave propagation.Herein we report the results of calculations and the newly observed physical phenomena.It is found that,for a given propagation,if the polarization is parallel to the wave vector,so also to the Poynting vector.In such a case,the phase velocity is identical to the energy velocity;the quasi P-wave degenerates to a pure P-wave along the propagation.It is also noted that if the polarization is parallel to the Poynting vector but not to the wave vector,the propagating wave cannot be a pure P-wave.Furthermore,the polarization in a quasi P-wave may deviate from the wave vector for more than 45°,but the deviation from the Poynting vector is always less than 45°.The energy velocity of a quasi SV-wave can be larger than that of the quasi P-wave in some propagation directions,even though the phase velocity of a quasi SV-wave may never be larger than either the phase velocity or energy velocity of the quasi P-wave.Finally,in case of parameters ε=0 and δ*≠0,the polarization of a quasi P-wave has an observed symmetry at a 45°phase angle.The anisotropy of a hexagonal system solid determines if a pure P-wave can be created and what the propagation direction is for a plane wave propagating inside such a hexagonal system solid.展开更多
In [1], we introduced the concept of z-transformation graphs of perfect matchings of hexagonal systems and showed that the z-transformation graph of perfect matchings of a hexagonal system has at most two vertices of...In [1], we introduced the concept of z-transformation graphs of perfect matchings of hexagonal systems and showed that the z-transformation graph of perfect matchings of a hexagonal system has at most two vertices of degree one. In this paper, we enumerate the hexagonal systems whose z-transformation graphs have a vertex of degree one. In particular, such hexagonal systems with various symmetries are also enumerated.展开更多
基金Supported by the National Natural Science Foundation of China(Grant No.11261059)
文摘Let Ln be the hexagonal chain graph, Fn be the hexacyclic system graph and Mn be the MSbius hexacyclic system graph. Derflinger and Sofer gave the spectra of Ln and Fn by using group theoretical method. Later, Gutman gave the spectra of them using a polynomial result due to Godsil and McKay. In this paper, we give a simple and direct method to determine the characteristic polynomial and spectra of Fn and Ln. By the method, we give the characteristic polynomial and spectrum of Mn that is new. Additionally, the exact values of total π-electron energy and the nullities of Ln, Fn and Mn are obtained, and the bounds for the energy of Ln and Mn are also considered.
基金National Natural Science Foundation of China (No. 10901034)Chenguang Program of Shanghai Education Development Foundation,China (No. 2008CG40)
文摘A formula was proved for computing the zeroth-order general Randic index of a hexagonal system to explore the correlation between the zeroth-order general Randic index and the π-electronic energy of a hexagonal system.As a consequence,the extremal hexagonal systems with minimum or maximum zeroth-order general Randic index were completely characterized.Moreover,by using the least-square fit method and regression analysis,a new and close relation was found between the zeroth-order general Randic index and the π-electronic energy of a hexagonal system.So the zeroth-order general Randic index is a good measure of the π-electronic energies for benzenoid hydrocarbons.
基金Supported by the National Natural Science Foundation of China (Grant No.11961041)the Natural Science Foundation of Gansu Province (Grant No.21JR11RA065)the Excellent Postgraduates of Gansu Provincial Department of Education “Star of Innovation” Foundation (Grant No.2021CXZX-594)。
文摘The A_(α)-matrix of a graph G is defined as A_(α)(G)=αD(G)+(1-α)A(G)(α∈[0,1]),given by Nikiforov in 2017,where A(G) and D(G) are,respectively,the adjacency matrix and the degree matrix of graph G.Let F_(n)and M_(n)be hexacyclic system graph and Möbius hexacyclic system graph,respectively.In this paper,according to the determinant and the eigenvalues of a circulant matrix,we firstly present Aα-characteristic polynomial and Aα-spectrum of F_(n)(resp.,M_(n)).Furthermore,we obtain the upper bound of the Aα-energy of F_(n)(resp.,M_(n)).
基金the National Natural Science Foundation of China(12274170 and 52225203)。
文摘Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown that this structure gives it exceptional physical properties that exceed those of cubic diamond,making it highly promising for groundbreaking applications in superhard cutting tools,wide-bandgap semiconductor devices,and materials for extreme environments.As a result,the controllable synthesis of hexagonal diamond has emerged as a cutting-edge research focus in materials science.This review briefly outlines the progress in this area,with a focus on the mechanisms governing its key synthesis conditions,its intrinsic physical properties,and its potential applications in various fields.
基金supported by the National Key Research and Development Program Project(2024YFF0726104)Key Laboratory of Modern Optical Technologies of the Education Ministry of China,Soochow University(Grant No.KJS2135)+1 种基金a China Postdoctoral Science Foundation Funded Project(Grant No.2024M751236)the Jiangxi Provincial Natural Science Foundation(Grant No.20232BAB211030).
文摘Negatively charged boron vacancy(V_(B)^(-))spin defects are stable in nanoscale hexagonal boron nitride(hBN)flakes,which can be easily integrated into two-dimensional materials and devices to serve as both sensors and protective materials.Ion irradiation is frequently employed to create V_(B)^(-)spin defects in hBN.However,the optimal ion irradiation parameters remain unclear,even though they play a crucial role in determining the depth and density of the defects,which in turn affect sensing sensitivity.In this work,we optimize the carbon ion irradiation parameters for creating V_(B)^(-)spin defects by varying the irradiation dose and the incident angle.For 30 keV carbon ion irradiation,the optimal irradiation dose to create a V_(B)^(-)ensemble is determined to be 4×10^(13)ions/cm^(2),and both continuous and pulsed optically detected magnetic resonance measurements are used to estimate the magnetic sensitivity and spin coherence properties.Moreover,the incident angle of energetic ions is found to influence both the depth and density distributions of the V_(B)^(-)ensemble,a factor that is often overlooked.These results pave the way for improving the performance of quantum sensors based on hBN spin defects by optimizing the irradiation parameters.
基金the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.48)。
文摘It is significant to process textures with special functions similar to animal surfaces based on bionics and improve the friction stability and contact comfort of contact surfaces for the surface texture design of tactile products.In this paper,a bionic hexagonal micro-convex texture was prepared on an acrylic surface by laser processing.The friction mechanism of a finger touching the bionic hexagonal micro-convex texture under different touch speeds and pressures,and the effect of the height of the texture on tactile perception were investigated by finite element,subjective evaluation,friction,and EEG tests.The results showed that the deformation friction was the main friction component when the finger touched the bionic hexagonal texture,and the slipperiness and friction factor showed a significant negative correlation.As the touch speed decreased or the touch force increased,the hysteresis friction of the fingers as well as the interlocking friction increased,and the slipperiness perception decreased.The bionic hexagonal texture with higher convexity caused a higher friction factor,lower slipperiness perception,and lower P300 peak.Hexagonal textures with lower convexity,lower friction factor,and higher slipperiness perception required greater brain attentional resources and intensity of tactile information processing during tactile perception.
基金financially supported by the National Key Research&Development Plan(No.2022YFE0110600)the National Natural Science Foundation of China(Nos.52171117,52371113,92263201 and 52175306)+3 种基金Qing Lan Project(No.54944004)the Basic Research Program of Jiangsu(Nos.BK20232011 and BK20232025)the Postdoctoral Fellowship Program of CPSF(No.GZC20233481)Tuoyuan project of Nanjing Tech University(No.20230113)
文摘Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 77 K over a broad strain rate range from 0.001 to 1 s^(-1).A critical strain rate of approximately 0.5 s^(-1)was identified,above which ductility exhibits a pronounced reduction,whereas below this threshold,ductility remains relatively stable.Through comprehensive analyses of strain evolution,deformed microstructure,and fracture morphology,this behavior is attributed to severe localized adiabatic heating resulting from inhomogeneous deformation,rather than conventional twin or shear mechanisms.
基金supported by the National Natural Science Foundation of China(Grant No.12204130)the Fundamental Research Funds for the Central University of China(Grant No.2019ZDPY16)+2 种基金the Basic Research Project of Xuzhou City(Grant No.KC22043)the support funded by the Graduate Innovation Program of China University of Mining and Technology(Grant Nos.2024WLJCRCZL266 and 2024WLJCRCZL294)the Postgraduate Research Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_2692)。
文摘In this study,we employed molecular dynamics simulations to investigate the interfacial thermal conductance(ITC)and phonon transport of heterostructures composed of graphene(GE)and quasi-hexagonal phase fullerene(qHPC60).We examined the effects of size,interface interaction coefficients,and thermal equilibrium time on the ITC of the GE/qHPC60 heterostructure.
基金supported by the National Natural Science Foundation of China(Grant Nos.11727902,12074372,12174385,12334014,and 12304112).
文摘Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.
基金Project supported by the Scientific and Technological Innovation Team of Nanjing(NINGJIAOGAOSHI 2021 No.16)。
文摘Enhancing the electrocatalytic activity of the electrode materials,specifically oxygen reduction reaction(ORR),at lower operating temperatures(<600℃)is the prime rank to realize the commercialization of solid oxide fuel cells(SOFCs)research.Herein,a new hexagonal structure-based cathode material was developed with the co-doping of Gd_(2)O_(3)and Cr_(2)O_(3)of parent SrFe_(12)O_(19)oxide,respectively.At 550-475℃,Sr_(0.90)Gd_(0.10)Fe_(11.90)Cr_(0.10)O_(19)(SFO-10)cathode sample leading to the large peak power density(PPD)of 395 mW/cm^(2),has appropriate surface oxygen defects(O_(β))up to 17%,as verified by X-ray photoelectron microscopy(XPS).Theoretical calculations reveal that the co-doping of Gd and Cr oxides creates lattice disorder at the hexagonal lattice,which decreases the energy barrier for ion transport and enhances the electrocatalytic characteristics of ORR.Consequently,the SFO-10 cathode shows a favorable ORR activity with the least lower polarization resistance(ASR)at 550℃with gadolinium-doped ceria(GDC)electrolyte.This work provides a self-assembled single-phase hexagonal cathode to accelerate the lowtemperature hindrance of SOFC technology.
基金supported by the National Natural Science Foundation of China(No.12025301)the Tsinghua University Initiative Scientific Research Program.
文摘Track reconstruction algorithms are critical for polarization measurements.Convolutional neural networks(CNNs)are a promising alternative to traditional moment-based track reconstruction approaches.However,the hexagonal grid track images obtained using gas pixel detectors(GPDs)for better anisotropy do not match the classical rectangle-based CNN,and converting the track images from hexagonal to square results in a loss of information.We developed a new hexagonal CNN algorithm for track reconstruction and polarization estimation in X-ray polarimeters,which was used to extract the emission angles and absorption points from photoelectron track images and predict the uncer-tainty of the predicted emission angles.The simulated data from the PolarLight test were used to train and test the hexagonal CNN models.For individual energies,the hexagonal CNN algorithm produced 15%-30%improvements in the modulation factor compared to the moment analysis method for 100%polarized data,and its performance was comparable to that of the rectangle-based CNN algorithm that was recently developed by the Imaging X-ray Polarimetry Explorer team,but at a lower computational and storage cost for preprocessing.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1403000,X.Z.No.2021YFA1400200,X.Z.+6 种基金No.2022YFA1204900,H.P.and No.2020YFA0308800,J.S.)the National Natural Science Foundation of China(Grant No.12274446,X.Z.No.12374172,J.S.No.11974045,J.S.No.61888102,J.S.)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000,J.G.&X.Z.)。
文摘Topological physics has evolved from its initial focus on fermionic systems to the exploration of bosonic systems,particularly phononic excitations in crystalline materials.Two-dimensional(2D)topological phonons emerge as promising candidates for future technological applications.Currently,experimental verification of 2D topological phonons has remained exclusively limited to graphene,a constraint that hinders their applications in phononic devices.Here,we report experimental evidence of topological phonons in monolayer hexagonal boron nitride using advanced high-resolution electron energy loss spectroscopy.Our high-precision measurements explicitly demonstrate two topological nodal rings in monolayer hexagonal boron nitride,protected by mirror symmetry,expanding the paradigm of 2D topological phonons beyond graphene.This research not only deepens fundamental understanding of 2D topological phonons,but also establishes a phononic device platform based on wide-bandgap insulators,crucial for advancements in electronics and photonics applications.
文摘In this paper,we propose a numerical calculation model of the multigroup neutron diffusion equation in 3D hexagonal geometry using the nodal Green's function method and verified it.We obtained one-dimensional transverse integrated equations using the transverse integration procedure over 3D hexagonal geometry and denoted the solutions as a nodal Green's functions under the Neumann boundary condition.By applying a quadratic polynomial expansion of the transverse-averaged quantities,we derived the net neutron current coupling equation,equation for the expansion coefficients of the transverse-averaged neutron flux,and formulas for the coefficient matrix of these equations.We formulated the closed system of equations in correspondence with the boundary conditions.The proposed model was tested by comparing it with the benchmark for the VVER-440 reactor,and the numerical results were in good agreement with the reference solutions.
基金Supported by the National Natural Science Foundation of China (Nos. 11902293 and 12272353)。
文摘In this paper,the mechanical response of a one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)thin film is analyzed under electric and temperature loads.Based on the Euler-Bernoulli beam theory,a theoretical model is proposed,resulting in coupled governing integral equations that account for interfacial normal and shear stresses.To numerically solve these integral equations,an expansion method using orthogonal Chebyshev polynomials is employed.The results provide insights into the interfacial stresses,axial force,as well as axial and vertical deformations of the PQC film.Additionally,fracture criteria,including stress intensity factors,mode angles,and the J-integral,are evaluated.The solution is compared with the membrane theory,neglecting the normal stress and bending deformation.Finally,the effects of stiffness and aspect ratio on the PQC film are thoroughly discussed.This study serves as a valuable guide for controlling the mechanical response and conducting safety assessments of PQC film systems.
文摘Silicon carbide(SiC)junction barrier Schottky(JBS)diode has been widely used in power electronic systems due to its excellent physical characteristics and electrical performance,and the structural design of its source area has a particularly significant impact on the performance.This study provides a comparative analysis of the SiC JBS diode performance of different hexagonal structures,aiming to provide theoretical support and practical guidance for the optimization of JBS diode performance.Through theoretical derivation,experimental verification and data processing,the paper deeply analyzes the influence of hexagonal structure on JBS diode current distribution and breakdown voltage,and proposes a targeted optimization strategy.
基金support provided by the Ministry of Higher Education Malaysia under the Fundamental Research Grant Scheme(FRGS)(No.FRGS/1/2024/TK08/XMU/02/1)supported by the PETRONAS-Academia Collaboration Dialogue(PACD 2023)grant,provided by PETRONAS Research Sdn.Bhd.(PRSB)+6 种基金the Ministry of Science,Technology and Innovation(MOSTI)Malaysia under the Strategic Research Fund(SRF)(S.22015)supported by the National Natural Science Foundation of China(No.22202168)Guangdong Basic and Applied Basic Research Foundation(No.2021A1515111019)support from the State Key Laboratory of Physical Chemistry of Solid Surfaces,Xiamen University(No.2023X11)supported by the Embassy of the People's Republic of China in Malaysia(EENG/0045)funded by Xiamen University Malaysia Investigatorship Grant(No.IENG/0038)Xiamen University Malaysia Research Fund(ICOE/0001,XMUMRF/2021-C8/IENG/0041 and XMUMRF/2025-C15/IENG/0080).
文摘Despite advances in photocatalytic half-reduction reactions,challenges remain in effectively utilizing electron-hole pairs in concurrent redox processes.The present study involved the construction of a p-n junction Co_(3)O_(4)/Zn_(3)In_(2)S_(6)(CoZ)hybrid with a complementary band edge potential.The photocatalyst formed by the 2D assembled-nanostructure portrayed an optimal yield of 13.8(H_(2))and 13.1(benzaldehyde)mmol g^(-1)h^(-1)when exposed to light(λ>420 nm),surpassing 1%Pt-added ZIS(12.4(H_(2))and 10.71(benzaldehyde)mmol g^(-1)h^(-1)).Around 95%of the electron-hole utilization rate was achieved.The solar-to-hydrogen(STH)and apparent quantum yield(AQY)values of 0.466%and 4.96%(420nm)achieved by this system in the absence of sacrificial agents exceeded those of previous works.The exceptional performance was mostly ascribed to the synergistic development of adjoining p-n heterojunctions and the built-in electric field for effective charge separation.Moreover,scavenger studies elucidated the intricate mechanistic enigma of the dual-redox process,in which benzaldehyde was produced via O-H activation and subsequent C-H cleavage of benzyl alcohol over CoZ hybrids.Furthermore,the widespread use of the optimal 1-CoZ composites was confirmed in multiple photoredox systems.This work presents an innovative perspective on the construction of dual-functioning p-n heterojunctions for practical photoredox applications.
基金Acknowledgements The authors would like to sincerely thank the anonymous referees for providing some helpful comments and suggestions in improving the manuscript. This work was supported by the National Natural Science Foundation of China （Grants Nos. 11371180, 11401279）.
文摘The anti-forcing number of a perfect matching M of a graph G is the minimal number of edges not in M whose removal makes M a unique perfect matching of the resulting graph. The anti-forcing spectrum of G is the set of anti-forcing numbers over all perfect matchings of G. In this paper, we prove that the anti-forcing spectrum of any cata-condensed hexagonal system is continuous, that is, it is a finite set of consecutive integers.
基金supported by the National Natural Science Foundation of China(Grant No.40974078)the Physical Sciences Division at University of Chicago
文摘Based on the reported physical parameters for hexagonal system solids,we have calculated the effects of anisotropy on polarization of plane P-wave propagation.Herein we report the results of calculations and the newly observed physical phenomena.It is found that,for a given propagation,if the polarization is parallel to the wave vector,so also to the Poynting vector.In such a case,the phase velocity is identical to the energy velocity;the quasi P-wave degenerates to a pure P-wave along the propagation.It is also noted that if the polarization is parallel to the Poynting vector but not to the wave vector,the propagating wave cannot be a pure P-wave.Furthermore,the polarization in a quasi P-wave may deviate from the wave vector for more than 45°,but the deviation from the Poynting vector is always less than 45°.The energy velocity of a quasi SV-wave can be larger than that of the quasi P-wave in some propagation directions,even though the phase velocity of a quasi SV-wave may never be larger than either the phase velocity or energy velocity of the quasi P-wave.Finally,in case of parameters ε=0 and δ*≠0,the polarization of a quasi P-wave has an observed symmetry at a 45°phase angle.The anisotropy of a hexagonal system solid determines if a pure P-wave can be created and what the propagation direction is for a plane wave propagating inside such a hexagonal system solid.
基金This work is supported by the National Natural Sciences Foundation China.
文摘In [1], we introduced the concept of z-transformation graphs of perfect matchings of hexagonal systems and showed that the z-transformation graph of perfect matchings of a hexagonal system has at most two vertices of degree one. In this paper, we enumerate the hexagonal systems whose z-transformation graphs have a vertex of degree one. In particular, such hexagonal systems with various symmetries are also enumerated.
