Skyrmions emerging in centrosymmetric materials have garnered significant interest.GdGa_(2),a recently discovered centrosymmetric antiferromagnet with a triangular lattice,has been proposed to host possible Néel-...Skyrmions emerging in centrosymmetric materials have garnered significant interest.GdGa_(2),a recently discovered centrosymmetric antiferromagnet with a triangular lattice,has been proposed to host possible Néel-type skyrmions exhibiting an extremely short magnetic periodicity in the so-called A-phases.Here,we report the magnetic and magnetotransport properties of GdGa_(2) single crystals.Hall anomalies beyond magnetization scaling emerge at intermediate magnetic fields,coinciding with the skyrmion-hosting A-phases.The small amplitude of the Hall anomalies may be attributed to the short period of the spin textures.In contrast,the transport behavior of TbGa_(2) single crystals is well described by a conventional two-band model.This discrepancy likely arises from distinct Ruderman–Kittel–Kasuya–Yosida interaction strengths and/or magnetic anisotropy between the two crystals.Our results establish GdGa_(2) as a new material platform for the exploration of skyrmion physics in centrosymmetric systems.展开更多
Acoustic-vortex(AV)tweezers ensure stable particle trapping at a zero-pressure center,while particle assembly between two vortex cores is still prevented by the high-potential barrier.Although a one-dimensional low-pr...Acoustic-vortex(AV)tweezers ensure stable particle trapping at a zero-pressure center,while particle assembly between two vortex cores is still prevented by the high-potential barrier.Although a one-dimensional low-pressure attractive path of particle assembly can be constructed by the interference between two independent cylindrical Bessel beams,it remains challenging to create two-dimensional(2D)neighboring vortexes using a source array in practical applications.In this paper,a three-step phase-reversal strategy of 2D particle assembly based on the synchronized evolution of a centrosymmetric array of M off-axis acoustic vortexes(OA-AVs)with a preset radial offset is proposed based on a ring array of planar sources.By introducing initial vortex phase differences of-2π/M and+2π/M to the vortex array,low-pressure patterns of an M-sided regular polygon and M-branched star are formed by connecting the vortex cores and the field center before and after the tangent state of adjacent OA-AVs.Center-oriented particle assembly is finally realized by a central AV constructed by coincident in-phase OA-AVs.The capability of particle manipulation in the lateral and radial directions is demonstrated by low-pressure patterns with acoustic radiation forces pointing to the field center during a synchronized central approach.The field evolution is certified by experimental field measurements for OA-AVs with different vo rtex numbers,initial vortex phase differences,and radial offsets using a ring array of 16 planar sources.The feasibility of particle assembly in two dimensions is also verified by the accurate manipulation of four particles using the low-pressure patterns of a four-sided polygon,a four-branched star,and a central AV in experiments.The three-step strategy paves a new way for 2D particle assembly based on the synchronize d evolution of centrosymmetric OA-AVs using a simplified single-sided source array,exhibiting excellent potential for the precise navigation and manipulation of cells and particles in biomedical applications.展开更多
To optimize secondary air nozzle structure in purifying burner,this study focused on the comparison of purification,combustion and NO_(x)emission characteristics of pulverized coal preheated by a 30 kW purifying burne...To optimize secondary air nozzle structure in purifying burner,this study focused on the comparison of purification,combustion and NO_(x)emission characteristics of pulverized coal preheated by a 30 kW purifying burner with coaxial and centrosymmetric structures.Centrosymmetric structure shifted the position of main burning region down in high-temperature reduction unit(HTRU),and the number of branches differently influenced the temperature in different regions with this structure.For reductive gas components,CO concentration with centrosymmetric structure was higher compared to coaxial structure,while the differences in H_(2)and CH_(4)concentrations were smaller.Centrosymmetric structure was more disadvantageous to improve physicochemical properties of pulverized coal compared to coaxial structure,and this structure with four branches further deteriorated its properties compared to two branches.In mild combustion unit(MCU),the temperature at top was lower with centrosymmetric structure,while was higher in the rest.Centrosymmetric structure more effectively reduced NO_(x)emission compared to coaxial structure,but with slight sacrifice of combustion efficiency(η).Moreover,both two-branch and four-branch centrosymmetric structures realized ultra-low NO_(x)emission(<50 mg·m^(-3))with high η of over 98.50%,and the former was more advantageous.With this optimal structure,η and NO_(x)emission were 99.25%and 40.42 mg·m^(-3).展开更多
In this letter, excited state dynamics of TPZ2, a centrosymmetric PRODAN dye, has been studied by using several time-resolved spectroscopy techniques. Fluorescence quantum yield of TPZ2 is found to be 0.50 in both ace...In this letter, excited state dynamics of TPZ2, a centrosymmetric PRODAN dye, has been studied by using several time-resolved spectroscopy techniques. Fluorescence quantum yield of TPZ2 is found to be 0.50 in both acetonitrile and ethanol solution. The radiative decay rate of the excited state of TPZ2 is determined to be 2.0×10^8 s^-1. Meanwhile, highly efficient triplet state and singlet oxygen generation have been observed in TPZ2 and the intersystem crossing（ISC） rate is determined to be 2.0×10^8s^-1. The almost identical ISC and non-radiative decay rates indicate that ISC is the only non-radiative decay pathway in TPZ2. Thus, dual excited state（S1） deactivation mechanism（50/50, fluorescence/ISC） of TPZ2 is proposed.Because of this unique property, TPZ2 has the potential to be used as biocompatible imaging and photodynamic therapy agent in the same time.展开更多
The current paper is mainly devoted for solving centrosymmetric linear systems of equations. Formulae for the determinants of tridiagonal centrosymmetric matrices are obtained explicitly. Two efficient computational a...The current paper is mainly devoted for solving centrosymmetric linear systems of equations. Formulae for the determinants of tridiagonal centrosymmetric matrices are obtained explicitly. Two efficient computational algorithms are established for solving general centrosymmetric linear systems. Based on these algorithms, a MAPLE procedure is written. Some illustrative examples are given.展开更多
Current-induced spin generations are of significant importance for electrically controllable magnetization.Due to symmetry constraints,linear spin generation is absent in centrosymmetric magnets and nonlinear contribu...Current-induced spin generations are of significant importance for electrically controllable magnetization.Due to symmetry constraints,linear spin generation is absent in centrosymmetric magnets and nonlinear contributions become crucial.However,nonlinear spin generations have few examples in centrosymmetric compensated magnets with opposite-spin sublattices,which hinders electric control of associated magnetization.Here,we study nonlinear spin generations in altermagnets,a new type of compensated magnets.In a square altermagnetic model,both staggered and uniform nonlinear spin generations appear at opposite-spin sublattices.They vary as the magnetization direction rotates,with emerging out-of-plane components that can be utilized in perpendicular magnetization switching of high-density storage devices.By first-principles calculations,out-of-plane,staggered nonlinear spin generations are found to be considerable in a typical altermagnet,Fe_(2)Se_(2)O monolayer.Our findings provide opportunities for electrically manipulating magnetization and designing energy-efficient magnetic devices based on compensated magnets.展开更多
Chirality is a widespread phenomenon in nature,where two non-superimposable enantiomers exist with one being the mirror image of the other.The interplay between chirality and magnetism has recently drawn intensive int...Chirality is a widespread phenomenon in nature,where two non-superimposable enantiomers exist with one being the mirror image of the other.The interplay between chirality and magnetism has recently drawn intensive interest in non-centrosymmetric magnetic materials absent of both spatial and time inversion symmetries[1].Among various chiral magnetic effects,the electrical manifestation of the magneto-chiral effect is crucial for both fundamental science and technological applications[2,3].The non-reciprocal resistance depending on the inner product of the magnetic field(H)and the current density U),termed the electrical magneto-chiral effect(eMChE),has recently been demonstrated in correlated oxides[4,5].展开更多
The separation of photogenerated electron–hole pairs is vitally important for photocatalysis,which can be effectively promoted by polarization field.However,it only manifests in piezoelectric/pyroelectric/ferroelectr...The separation of photogenerated electron–hole pairs is vitally important for photocatalysis,which can be effectively promoted by polarization field.However,it only manifests in piezoelectric/pyroelectric/ferroelectric materials that have a non-centrosymmetric structure.Here,we demonstrate that the polarization enhanced photocatalysis(with wide spectra from ultraviolet(UV)light to visible light)can be achieved in centrosymmetric semiconductors,such asδ-MnO_(2) and TiO_(2) nanosheets integrated nanoflowers,by using the strain-gradient-induced flexoelectric polarization that is always overlooked in polarization-enhanced catalysis.Under ultrasonic and illumination excitation,the organic pollutants(methylene blue(MB),etc.)can be effectively degraded within 30 min with excellent stability and repeatability.Compared with photocatalysis,the flexo-photocatalytic performance of above centrosymmetric semiconductors is substantially increased by 85%.Moreover,the factors related to flexo-photocatalysis such as material morphology,mechanical stimuli source,and adsorption are explored to deeply understand the mechanism of flexo-photocatalysis.This work opens up a way for high-performance photocatalysis in centrosymmetric semiconductors.展开更多
Spontaneous polarization due to symmetry breaking in the transition metal ditellurides(MTe_(2))family exhibits intriguing sliding ferroelectricity.Although theoretical predictions of MTe_(2)ferroelectric metals with n...Spontaneous polarization due to symmetry breaking in the transition metal ditellurides(MTe_(2))family exhibits intriguing sliding ferroelectricity.Although theoretical predictions of MTe_(2)ferroelectric metals with noncentrosymmetric stacking have been reported,the realization of such polarization structure remains a challenge.Here,we demonstrate the synthesis of PtTe_(2)with non-centrosymmetric stacking layers,in contrast to bulk AA stacking,achieved within a scanning transmission electron microscope(STEM)by irradiating amorphous PtxTeythin flms with an electron beam probe.Cross-sectional STEM imaging combined with frst-principles calculations reveals that the diverse stacking confgurations due to an intralayerπ-stacking system break centrosymmetry in PtTe_(2),giving rise to the out-of-plane polarization.Three-dimensional atomic positions identifed by the atomic electron tomography method further demonstrate the local distortions associated with the non-centrosymmetric stacking layers in PtTe_(2).The understanding of the atomic origin of polarization in PtTe_(2)is of signifcant importance for developing devices that integrate ferroelectricity with metallicity.展开更多
Three phosphates Rb_(2)Zn_(3)(P_(2)O_(7))_(2)and Cs_(2)M_(3)(P_(2)O_(7))_(2)(M=Zn and Mg) were successfully synthesized by a high-temperature solution method.Their structures were determined by single-crystal X-ray di...Three phosphates Rb_(2)Zn_(3)(P_(2)O_(7))_(2)and Cs_(2)M_(3)(P_(2)O_(7))_(2)(M=Zn and Mg) were successfully synthesized by a high-temperature solution method.Their structures were determined by single-crystal X-ray diffraction,which shows that the three structures all display three-dimensional [M_(3)P_(4)O_(2)_(0)]^(14-) (M=Zn and Mg) frameworks composed of isolated P_(2)O_(7) dimers and MO_(4) (M=Zn and Mg) tetrahedra with Rb⁺/Cs⁺ cations located in the space of the frameworks to balance charges.But owing to the cationic size effect,they are not iso-structural.Rb_(2)Zn_(3)(P_(2)O_(7))_(2)crystallizes in the non-centrosymmetric P2₁ space group,whereas Cs_(2)M_(3)(P_(2)O_(7))_(2)(M=Zn and Mg) crystallize in the centrosymmetric P2₁/c space group.And Rb_(2)Zn_(3)(P_(2)O_(7))_(2)exhibits a second harmonic generation (SHG) response as large as that of KH_(2) PO_(4) (KDP).Combining electronic structure and SHG density calculations,we studied the effects of ZnO_(4) tetrahedra on the SHG response of Rb_(2)Zn_(3)(P_(2)O_(7))_(2).Furthermore,a structural comparison is also carried out in Rb_(2)Zn_(3)(P_(2)O_(7))_(2)and Cs_(2)M_(3)(P_(2)O_(7))_(2)(M=Zn and Mg).展开更多
Rational structural design and modification based on known compounds is an effective strategy to explore new nonlinear optical(NLO)materials.Here,three new rare-earth(RE)oxythiogermanates Eu_(18)Ge_(9)O_(5)S_(31)(1),C...Rational structural design and modification based on known compounds is an effective strategy to explore new nonlinear optical(NLO)materials.Here,three new rare-earth(RE)oxythiogermanates Eu_(18)Ge_(9)O_(5)S_(31)(1),Ca_(3.32)Eu_(14.68)Ge_(9)O_(5)S_(31)(2)and Ba_(3)Eu_(15)Ge_(9)O_(5)S_(31)(3)were obtained by the novel cation and anion co-partial substitution strategy from the parentβ-Eu2GeS4(0),which induces centrosymmetric to noncentrosymmetric(NCS)structural transformation and NLO activities.They crystallize with a pseudo-zero dimensional structure in the chiral R3 space group,featuring almost linearly arranged isolated GeS_(4)and GeOS_(3)tetrahedra.Their optical band gaps were determined to be 2.18,2.23 and 2.24 eV,respectively.1 and 2 show balanced NLO properties with moderate second-harmonic generation(SHG)responses(0.5 and 0.6×AGS)and high laser-induced damage thresholds(LIDTs)(3.3×AGS).Moreover,theoretical calculations show that their NLO properties are determined by the synergistic effect of GeS_(4)and GeOS_(3)tetrahedra.This work enriches the chemistry of rarely studied RE oxychalcogenides and provides a fresh route for designing NCS structures targeting diverse applications.展开更多
Two fluoride nitrates named RbSnF_(2)NO_(3)and Rb_(2)SbF_(3)(NO_(3))_(2)have been successfully synthesized using a rapid evaporation concentration method by introducing Sn^(2+)/Sb^(3+)cations with stereochemically act...Two fluoride nitrates named RbSnF_(2)NO_(3)and Rb_(2)SbF_(3)(NO_(3))_(2)have been successfully synthesized using a rapid evaporation concentration method by introducing Sn^(2+)/Sb^(3+)cations with stereochemically active lone pairs into the nitrate system.The discrepancy in the cation sizes and coordination modes induces the different symmetries of these two title compounds,RbSnF_(2)NO_(3)crystallizing in a centrosymmetric(CS)space group of C2/m,while Rb_(2)SbF_(3)(NO_(3))_(2)in a noncentrosymmetric(NCS)space group of P2_(1).展开更多
By introducing Sb^(3+)cations with a stereochemically active lone pair in the sulfate system,two antimony fluoride sulfates with the same stoichiometric ratio,namely,K_(2)SO_(4)·(SbF_(3))_(2)and Rb_(2)SO_(4)·...By introducing Sb^(3+)cations with a stereochemically active lone pair in the sulfate system,two antimony fluoride sulfates with the same stoichiometric ratio,namely,K_(2)SO_(4)·(SbF_(3))_(2)and Rb_(2)SO_(4)·(SbF_(3))_(2),were successfully synthesized via mild hydrothermal reactions.The cooperative effects of the alkali metal cation size and lone pairs resulted in a different symmetry for these two title compounds.展开更多
New nonlinear optical(NLO)crystals have become an urgent need for extending laser wavelengths.By cation substitution between alkali metal(K+,Rb+),anion group arrangement transition was realized,and centrosymmetric Rb[...New nonlinear optical(NLO)crystals have become an urgent need for extending laser wavelengths.By cation substitution between alkali metal(K+,Rb+),anion group arrangement transition was realized,and centrosymmetric Rb[Te_(2)O_(4)(OH)_(5)](RTOH)(monoclinic,P21/c)and noncentrosymmetric K_(2)[Te_(3)O_(8)(OH)_(4)](KTOH)(orthorhombic,Fdd2)featuring corner/edge-sharing(Te_(4)O_(18))12-anion groups were successfully synthesized.These two compounds exhibit wide band gaps(>4.0 eV),high thermal stabilities(>290℃)and suitable birefringences(Δnexp>0.04).In addition,KTOH exhibits an SHG response about 0.6×KDP under 1064 nm fundamental light.First principles calculations were aslo performed,which demonstrated that their optical properties are mainly contributed by the TeO66-octahedral units.展开更多
A new deep-ultraviolet nonlinear optical crystal,Cs_(12)Zn_(4)(B_(5)O_(10))_(4),was synthesized via a high temperature solution method.The crystal structure was solved in the noncentrosymmetric space group(Cc,no.9).Ow...A new deep-ultraviolet nonlinear optical crystal,Cs_(12)Zn_(4)(B_(5)O_(10))_(4),was synthesized via a high temperature solution method.The crystal structure was solved in the noncentrosymmetric space group(Cc,no.9).Owing to the cation size effect,from X_(3)ZnB_(5)O_(10)(X=Na,K,and Rb)to Cs_(12)Zn_(4)(B_(5)O_(10))_(4),the structure changes from centrosymmetric to noncentrosymmetric.Cs_(12)Zn_(4)(B_(5)O_(10))_(4) exhibits a 3D[ZnB_(5)O_(10)]_(∞) network,however,X_(3)ZnB_(5)O_(10)(X=Na,K,and Rb)exhibits a 2D[ZnB_(5)O_(10)]_(∞)layer.It is worth mentioning that Cs_(12)Zn_(4)(B_(5)O_(10))_(4) displays a short cutoff edge(below 185 nm),which is remarkable among the reported Zn-containing NLO crystals.Meanwhile,the compound exhibits a moderate SHG response and melts congruently.In addition,the relationship between its structure and NLO properties was also discussed in detail using the density functional theory(DFT)method.展开更多
Two fluorine antimony nitrates named(NH_(4))_(3)SbF_(3)(NO_(3))_(3) and(NH_(4))_(3)SbF_(4)(NO_(3))_(2) have been successfully synthesized by a low temperature molten salt method.Although these two title compounds poss...Two fluorine antimony nitrates named(NH_(4))_(3)SbF_(3)(NO_(3))_(3) and(NH_(4))_(3)SbF_(4)(NO_(3))_(2) have been successfully synthesized by a low temperature molten salt method.Although these two title compounds possess NO_(3)^(-)groups and similar Sb-polyhedra,they exhibit completely different macroscopic centricities,(NH_(4))_(3)SbF_(3)(NO_(3))_(3) being noncentrosymmetric while(NH_(4))_(3)SbF_(4)(NO_(3))_(2) being centrosymmetric,which is induced by the discrepant coordination environments of Sb^(3+).Interestingly,the noncentrosymmetric(NH_(4))_(3)SbF_(3)(NO_(3))_(3) exhibits a strong second harmonic generation response(3.3×KDP),a large birefringence(0.098@546 nm)and a large band gap(3.77 eV),indicating its potential as a UV nonlinear optical material.Detailed structure-property analysis confirms that the superior optical property is due to the synergistic effect of the planar π-conjugated NO_(3)^(-)groups and the stereochemically active lone pair containing Sb^(3+)cations.展开更多
A new complex alkaline-earth metal borosilicate chloride Ba_(3)Ca4(BO_(3))_(3)(SiO4)Cl has been successfully synthesized by the high-temperature solution method.It crystallizes in the space group P6_(3)mc(no.186)of th...A new complex alkaline-earth metal borosilicate chloride Ba_(3)Ca4(BO_(3))_(3)(SiO4)Cl has been successfully synthesized by the high-temperature solution method.It crystallizes in the space group P6_(3)mc(no.186)of the hexagonal system.展开更多
The search for new non-centrosymmetric(NCS)crystals with wide energy-gaps(Eg)and strong secondharmonic generation(SHG)responses has become one of the greatest challenges in the mid-and farinfrared(MFIR)nonlinear optic...The search for new non-centrosymmetric(NCS)crystals with wide energy-gaps(Eg)and strong secondharmonic generation(SHG)responses has become one of the greatest challenges in the mid-and farinfrared(MFIR)nonlinear optical(NLO)field.In this work,a novel quaternary NCS material Sr_(5)ZnGa_(6)S_(15)(SZGS),which contains a complex 3D anionic framework and possesses the optical properties required for the MFIR NLO applications,especially the good balance between wide Eg(3.15 eV)and large SHG response(d_(ij)=1.2×AgGaS_(2)),has been discovered for the first time.Moreover,the result of theoretical calculation further indicates that the 3D[ZnGa_(6)S_(15)]^(10−)framework makes definitive contributions to the NLO properties.All these studies demonstrate that SZGS is a promising NLO candidate in the MFIR region.展开更多
We define an m-involution to be a matrix K ∈ Cn×n for which Km -= I. In this article, we investigate the class Sm （A） of m-involutions that commute with a diagonalizable matrix A E Cn×n. A number of basic...We define an m-involution to be a matrix K ∈ Cn×n for which Km -= I. In this article, we investigate the class Sm （A） of m-involutions that commute with a diagonalizable matrix A E Cn×n. A number of basic properties of Sm （A） and its related subclass Sm （A, X） are given, where X is an eigenvector matrix of A. Among them, Sm （A） is shown to have a torsion group structure under matrix multiplication if A has distinct eigenvalues and has non-denumerable cardinality otherwise. The constructive definition of Sm （A, X） allows one to generate all m-involutions commuting with a matrix with distinct eigenvalues. Some related results are also given for the class S,, （A） of m-involutions that anti-commute with a matrix A ∈ Cnn×n.展开更多
The title compound, 〔NH 4〕 6〔(CH 3CO) 2(Mo 8O 28 )〕·4H 2O, was produced from (NH 4) 6〔Mo 7O 24 〕·4H 2O aqueous solution in the presence of N 2H 4·H 2SO 4 and its structure ha...The title compound, 〔NH 4〕 6〔(CH 3CO) 2(Mo 8O 28 )〕·4H 2O, was produced from (NH 4) 6〔Mo 7O 24 〕·4H 2O aqueous solution in the presence of N 2H 4·H 2SO 4 and its structure has been determined by X ray single crystal analysis. The crystallographic data: C 4H 38 Mo 8N 6O 34 , M r =1481.92, triclinic, P1, a=8.127(2), b = 10\^373(2), c = 12.383(3) , α=99.51(3), β=105.47(3), γ=112.92(3)°, V=883.0(3) 3, Z=1, D c =2.787g/cm 3, F(000)= 712, μ =2.864 mm -1 , Final R =0.0368 and wR =0.0924 for 2926 reflections with I】2σ(I ). The X ray crystal structure analysis reveals that there is one independent molecule in the unit cell of the title compound which contains one centrosymmetric diacetyloctamolybdate anion, six ammonium cations and four water molecules.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12274125,12574117,12374105,12174103)。
文摘Skyrmions emerging in centrosymmetric materials have garnered significant interest.GdGa_(2),a recently discovered centrosymmetric antiferromagnet with a triangular lattice,has been proposed to host possible Néel-type skyrmions exhibiting an extremely short magnetic periodicity in the so-called A-phases.Here,we report the magnetic and magnetotransport properties of GdGa_(2) single crystals.Hall anomalies beyond magnetization scaling emerge at intermediate magnetic fields,coinciding with the skyrmion-hosting A-phases.The small amplitude of the Hall anomalies may be attributed to the short period of the spin textures.In contrast,the transport behavior of TbGa_(2) single crystals is well described by a conventional two-band model.This discrepancy likely arises from distinct Ruderman–Kittel–Kasuya–Yosida interaction strengths and/or magnetic anisotropy between the two crystals.Our results establish GdGa_(2) as a new material platform for the exploration of skyrmion physics in centrosymmetric systems.
基金funded by the National Nature Science Foundation of China(11934009,12174198,and 12227808)the Natural Science Foundation of Jiangsu Province,China(BE2022814)+2 种基金the Universal Technology for Primary and Secondary Schoolsthe National Research Institute for Teaching Materialsthe Qing Lan Project of Jiangsu Province,China。
文摘Acoustic-vortex(AV)tweezers ensure stable particle trapping at a zero-pressure center,while particle assembly between two vortex cores is still prevented by the high-potential barrier.Although a one-dimensional low-pressure attractive path of particle assembly can be constructed by the interference between two independent cylindrical Bessel beams,it remains challenging to create two-dimensional(2D)neighboring vortexes using a source array in practical applications.In this paper,a three-step phase-reversal strategy of 2D particle assembly based on the synchronized evolution of a centrosymmetric array of M off-axis acoustic vortexes(OA-AVs)with a preset radial offset is proposed based on a ring array of planar sources.By introducing initial vortex phase differences of-2π/M and+2π/M to the vortex array,low-pressure patterns of an M-sided regular polygon and M-branched star are formed by connecting the vortex cores and the field center before and after the tangent state of adjacent OA-AVs.Center-oriented particle assembly is finally realized by a central AV constructed by coincident in-phase OA-AVs.The capability of particle manipulation in the lateral and radial directions is demonstrated by low-pressure patterns with acoustic radiation forces pointing to the field center during a synchronized central approach.The field evolution is certified by experimental field measurements for OA-AVs with different vo rtex numbers,initial vortex phase differences,and radial offsets using a ring array of 16 planar sources.The feasibility of particle assembly in two dimensions is also verified by the accurate manipulation of four particles using the low-pressure patterns of a four-sided polygon,a four-branched star,and a central AV in experiments.The three-step strategy paves a new way for 2D particle assembly based on the synchronize d evolution of centrosymmetric OA-AVs using a simplified single-sided source array,exhibiting excellent potential for the precise navigation and manipulation of cells and particles in biomedical applications.
基金Postdoctoral Fellowship Program of CPSF(GZC20232672)CAS Project for Young Scientists in Basic Research(YSBR-028)the Strategic Priority Research Program(XDA29010200)are gratefully acknowledged.
文摘To optimize secondary air nozzle structure in purifying burner,this study focused on the comparison of purification,combustion and NO_(x)emission characteristics of pulverized coal preheated by a 30 kW purifying burner with coaxial and centrosymmetric structures.Centrosymmetric structure shifted the position of main burning region down in high-temperature reduction unit(HTRU),and the number of branches differently influenced the temperature in different regions with this structure.For reductive gas components,CO concentration with centrosymmetric structure was higher compared to coaxial structure,while the differences in H_(2)and CH_(4)concentrations were smaller.Centrosymmetric structure was more disadvantageous to improve physicochemical properties of pulverized coal compared to coaxial structure,and this structure with four branches further deteriorated its properties compared to two branches.In mild combustion unit(MCU),the temperature at top was lower with centrosymmetric structure,while was higher in the rest.Centrosymmetric structure more effectively reduced NO_(x)emission compared to coaxial structure,but with slight sacrifice of combustion efficiency(η).Moreover,both two-branch and four-branch centrosymmetric structures realized ultra-low NO_(x)emission(<50 mg·m^(-3))with high η of over 98.50%,and the former was more advantageous.With this optimal structure,η and NO_(x)emission were 99.25%and 40.42 mg·m^(-3).
基金funded by the National Natural Science Foundation of China (No. 11674101)
文摘In this letter, excited state dynamics of TPZ2, a centrosymmetric PRODAN dye, has been studied by using several time-resolved spectroscopy techniques. Fluorescence quantum yield of TPZ2 is found to be 0.50 in both acetonitrile and ethanol solution. The radiative decay rate of the excited state of TPZ2 is determined to be 2.0×10^8 s^-1. Meanwhile, highly efficient triplet state and singlet oxygen generation have been observed in TPZ2 and the intersystem crossing（ISC） rate is determined to be 2.0×10^8s^-1. The almost identical ISC and non-radiative decay rates indicate that ISC is the only non-radiative decay pathway in TPZ2. Thus, dual excited state（S1） deactivation mechanism（50/50, fluorescence/ISC） of TPZ2 is proposed.Because of this unique property, TPZ2 has the potential to be used as biocompatible imaging and photodynamic therapy agent in the same time.
文摘The current paper is mainly devoted for solving centrosymmetric linear systems of equations. Formulae for the determinants of tridiagonal centrosymmetric matrices are obtained explicitly. Two efficient computational algorithms are established for solving general centrosymmetric linear systems. Based on these algorithms, a MAPLE procedure is written. Some illustrative examples are given.
基金supported by the National Natural Science Foundation of China(Grant Nos.12374044,11904173,and 12004186)。
文摘Current-induced spin generations are of significant importance for electrically controllable magnetization.Due to symmetry constraints,linear spin generation is absent in centrosymmetric magnets and nonlinear contributions become crucial.However,nonlinear spin generations have few examples in centrosymmetric compensated magnets with opposite-spin sublattices,which hinders electric control of associated magnetization.Here,we study nonlinear spin generations in altermagnets,a new type of compensated magnets.In a square altermagnetic model,both staggered and uniform nonlinear spin generations appear at opposite-spin sublattices.They vary as the magnetization direction rotates,with emerging out-of-plane components that can be utilized in perpendicular magnetization switching of high-density storage devices.By first-principles calculations,out-of-plane,staggered nonlinear spin generations are found to be considerable in a typical altermagnet,Fe_(2)Se_(2)O monolayer.Our findings provide opportunities for electrically manipulating magnetization and designing energy-efficient magnetic devices based on compensated magnets.
基金financially supported by the National Key R&D Program of China(2022YFA1403000 and 2022YFA1403300)the National Natural Science Foundation of China(52072244,12104305,12074080,12274088,11874054,and 12104301)+3 种基金the Science and Technology Commission of Shanghai Municipality(21JC1405000 and 21PJ410800)The research used resources from Analytical Instrumentation Center(#SPST-AIC10112914)C?EM(EM02161943)in Shanghai Tech Universitysupported by the U.S.DOE Office of Science-Basic Energy Sciences,under Contract No.DE-AC02-06CH11357。
文摘Chirality is a widespread phenomenon in nature,where two non-superimposable enantiomers exist with one being the mirror image of the other.The interplay between chirality and magnetism has recently drawn intensive interest in non-centrosymmetric magnetic materials absent of both spatial and time inversion symmetries[1].Among various chiral magnetic effects,the electrical manifestation of the magneto-chiral effect is crucial for both fundamental science and technological applications[2,3].The non-reciprocal resistance depending on the inner product of the magnetic field(H)and the current density U),termed the electrical magneto-chiral effect(eMChE),has recently been demonstrated in correlated oxides[4,5].
基金supported by the National Natural Science Foundation of China(No.52202162).
文摘The separation of photogenerated electron–hole pairs is vitally important for photocatalysis,which can be effectively promoted by polarization field.However,it only manifests in piezoelectric/pyroelectric/ferroelectric materials that have a non-centrosymmetric structure.Here,we demonstrate that the polarization enhanced photocatalysis(with wide spectra from ultraviolet(UV)light to visible light)can be achieved in centrosymmetric semiconductors,such asδ-MnO_(2) and TiO_(2) nanosheets integrated nanoflowers,by using the strain-gradient-induced flexoelectric polarization that is always overlooked in polarization-enhanced catalysis.Under ultrasonic and illumination excitation,the organic pollutants(methylene blue(MB),etc.)can be effectively degraded within 30 min with excellent stability and repeatability.Compared with photocatalysis,the flexo-photocatalytic performance of above centrosymmetric semiconductors is substantially increased by 85%.Moreover,the factors related to flexo-photocatalysis such as material morphology,mechanical stimuli source,and adsorption are explored to deeply understand the mechanism of flexo-photocatalysis.This work opens up a way for high-performance photocatalysis in centrosymmetric semiconductors.
基金supported by the National Key R&D Program of China(Grant Nos.2024YFA1208201,2022YFA1403000,and 2021YFA1400204)the National Natural Science Foundation of China(Grant Nos.52322311,12334001,52427802,12174432,12250710675,and 52461160301)the support from Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)。
文摘Spontaneous polarization due to symmetry breaking in the transition metal ditellurides(MTe_(2))family exhibits intriguing sliding ferroelectricity.Although theoretical predictions of MTe_(2)ferroelectric metals with noncentrosymmetric stacking have been reported,the realization of such polarization structure remains a challenge.Here,we demonstrate the synthesis of PtTe_(2)with non-centrosymmetric stacking layers,in contrast to bulk AA stacking,achieved within a scanning transmission electron microscope(STEM)by irradiating amorphous PtxTeythin flms with an electron beam probe.Cross-sectional STEM imaging combined with frst-principles calculations reveals that the diverse stacking confgurations due to an intralayerπ-stacking system break centrosymmetry in PtTe_(2),giving rise to the out-of-plane polarization.Three-dimensional atomic positions identifed by the atomic electron tomography method further demonstrate the local distortions associated with the non-centrosymmetric stacking layers in PtTe_(2).The understanding of the atomic origin of polarization in PtTe_(2)is of signifcant importance for developing devices that integrate ferroelectricity with metallicity.
基金supported by the National Natural Science Foundation of China(Grant No.51972230,51802217,61835014,51890864,and 51890865)Natural Science Foundation of Tianjin(19JCZDJC38200)+1 种基金National Key R&D Program(Grant No.2016YFB0402103)Tianjin Science and technology plan Program(Grant No.19ZYPTJC00070).
文摘Three phosphates Rb_(2)Zn_(3)(P_(2)O_(7))_(2)and Cs_(2)M_(3)(P_(2)O_(7))_(2)(M=Zn and Mg) were successfully synthesized by a high-temperature solution method.Their structures were determined by single-crystal X-ray diffraction,which shows that the three structures all display three-dimensional [M_(3)P_(4)O_(2)_(0)]^(14-) (M=Zn and Mg) frameworks composed of isolated P_(2)O_(7) dimers and MO_(4) (M=Zn and Mg) tetrahedra with Rb⁺/Cs⁺ cations located in the space of the frameworks to balance charges.But owing to the cationic size effect,they are not iso-structural.Rb_(2)Zn_(3)(P_(2)O_(7))_(2)crystallizes in the non-centrosymmetric P2₁ space group,whereas Cs_(2)M_(3)(P_(2)O_(7))_(2)(M=Zn and Mg) crystallize in the centrosymmetric P2₁/c space group.And Rb_(2)Zn_(3)(P_(2)O_(7))_(2)exhibits a second harmonic generation (SHG) response as large as that of KH_(2) PO_(4) (KDP).Combining electronic structure and SHG density calculations,we studied the effects of ZnO_(4) tetrahedra on the SHG response of Rb_(2)Zn_(3)(P_(2)O_(7))_(2).Furthermore,a structural comparison is also carried out in Rb_(2)Zn_(3)(P_(2)O_(7))_(2)and Cs_(2)M_(3)(P_(2)O_(7))_(2)(M=Zn and Mg).
基金the financial support from the National Natural Science Foundation of China(22071212 and 22371246)the Natural Science Foundation of Yunnan Province(202401AS070120).
文摘Rational structural design and modification based on known compounds is an effective strategy to explore new nonlinear optical(NLO)materials.Here,three new rare-earth(RE)oxythiogermanates Eu_(18)Ge_(9)O_(5)S_(31)(1),Ca_(3.32)Eu_(14.68)Ge_(9)O_(5)S_(31)(2)and Ba_(3)Eu_(15)Ge_(9)O_(5)S_(31)(3)were obtained by the novel cation and anion co-partial substitution strategy from the parentβ-Eu2GeS4(0),which induces centrosymmetric to noncentrosymmetric(NCS)structural transformation and NLO activities.They crystallize with a pseudo-zero dimensional structure in the chiral R3 space group,featuring almost linearly arranged isolated GeS_(4)and GeOS_(3)tetrahedra.Their optical band gaps were determined to be 2.18,2.23 and 2.24 eV,respectively.1 and 2 show balanced NLO properties with moderate second-harmonic generation(SHG)responses(0.5 and 0.6×AGS)and high laser-induced damage thresholds(LIDTs)(3.3×AGS).Moreover,theoretical calculations show that their NLO properties are determined by the synergistic effect of GeS_(4)and GeOS_(3)tetrahedra.This work enriches the chemistry of rarely studied RE oxychalcogenides and provides a fresh route for designing NCS structures targeting diverse applications.
基金supported by the National Natural Science Foundation of China(no.21875146,21971171,22071158)the Fundamental Research Funds for the Central Universities(no.YJ201921).
文摘Two fluoride nitrates named RbSnF_(2)NO_(3)and Rb_(2)SbF_(3)(NO_(3))_(2)have been successfully synthesized using a rapid evaporation concentration method by introducing Sn^(2+)/Sb^(3+)cations with stereochemically active lone pairs into the nitrate system.The discrepancy in the cation sizes and coordination modes induces the different symmetries of these two title compounds,RbSnF_(2)NO_(3)crystallizing in a centrosymmetric(CS)space group of C2/m,while Rb_(2)SbF_(3)(NO_(3))_(2)in a noncentrosymmetric(NCS)space group of P2_(1).
基金supported by the National Natural Science Foundation of China(no.21971171 and 21875146)the Fundamental Research Funds for the Central Universities(no.YJ201921).
文摘By introducing Sb^(3+)cations with a stereochemically active lone pair in the sulfate system,two antimony fluoride sulfates with the same stoichiometric ratio,namely,K_(2)SO_(4)·(SbF_(3))_(2)and Rb_(2)SO_(4)·(SbF_(3))_(2),were successfully synthesized via mild hydrothermal reactions.The cooperative effects of the alkali metal cation size and lone pairs resulted in a different symmetry for these two title compounds.
基金supported by the National Natural Science Foundation of China(Grant No.51702232,51890864,51890865).
文摘New nonlinear optical(NLO)crystals have become an urgent need for extending laser wavelengths.By cation substitution between alkali metal(K+,Rb+),anion group arrangement transition was realized,and centrosymmetric Rb[Te_(2)O_(4)(OH)_(5)](RTOH)(monoclinic,P21/c)and noncentrosymmetric K_(2)[Te_(3)O_(8)(OH)_(4)](KTOH)(orthorhombic,Fdd2)featuring corner/edge-sharing(Te_(4)O_(18))12-anion groups were successfully synthesized.These two compounds exhibit wide band gaps(>4.0 eV),high thermal stabilities(>290℃)and suitable birefringences(Δnexp>0.04).In addition,KTOH exhibits an SHG response about 0.6×KDP under 1064 nm fundamental light.First principles calculations were aslo performed,which demonstrated that their optical properties are mainly contributed by the TeO66-octahedral units.
基金completed with the help of the West Light Foundation of the CAS(Grant No.2016-YJRC-2)the National Natural Science Foundation of China(Grant No.U1703127,61835014,and 51425206)+2 种基金the High-level Professional and Technical Personnel of Autonomous region,the Science and Technology Project of Urumqi(Grant No.G161020001)the Xinjiang Key Research and Development Program(Grant No.2016B02021)The authors also express their thanks to the“Fujian Institute of Innovation,CAS”for the support.
文摘A new deep-ultraviolet nonlinear optical crystal,Cs_(12)Zn_(4)(B_(5)O_(10))_(4),was synthesized via a high temperature solution method.The crystal structure was solved in the noncentrosymmetric space group(Cc,no.9).Owing to the cation size effect,from X_(3)ZnB_(5)O_(10)(X=Na,K,and Rb)to Cs_(12)Zn_(4)(B_(5)O_(10))_(4),the structure changes from centrosymmetric to noncentrosymmetric.Cs_(12)Zn_(4)(B_(5)O_(10))_(4) exhibits a 3D[ZnB_(5)O_(10)]_(∞) network,however,X_(3)ZnB_(5)O_(10)(X=Na,K,and Rb)exhibits a 2D[ZnB_(5)O_(10)]_(∞)layer.It is worth mentioning that Cs_(12)Zn_(4)(B_(5)O_(10))_(4) displays a short cutoff edge(below 185 nm),which is remarkable among the reported Zn-containing NLO crystals.Meanwhile,the compound exhibits a moderate SHG response and melts congruently.In addition,the relationship between its structure and NLO properties was also discussed in detail using the density functional theory(DFT)method.
基金supported by the National Natural Science Foundation of China(no.22122106,22071158,21971171).
文摘Two fluorine antimony nitrates named(NH_(4))_(3)SbF_(3)(NO_(3))_(3) and(NH_(4))_(3)SbF_(4)(NO_(3))_(2) have been successfully synthesized by a low temperature molten salt method.Although these two title compounds possess NO_(3)^(-)groups and similar Sb-polyhedra,they exhibit completely different macroscopic centricities,(NH_(4))_(3)SbF_(3)(NO_(3))_(3) being noncentrosymmetric while(NH_(4))_(3)SbF_(4)(NO_(3))_(2) being centrosymmetric,which is induced by the discrepant coordination environments of Sb^(3+).Interestingly,the noncentrosymmetric(NH_(4))_(3)SbF_(3)(NO_(3))_(3) exhibits a strong second harmonic generation response(3.3×KDP),a large birefringence(0.098@546 nm)and a large band gap(3.77 eV),indicating its potential as a UV nonlinear optical material.Detailed structure-property analysis confirms that the superior optical property is due to the synergistic effect of the planar π-conjugated NO_(3)^(-)groups and the stereochemically active lone pair containing Sb^(3+)cations.
基金supported by the Key Research Project of Frontier Science of CAS(Grant No.QYZDB-SSW-JSC049)the National Natural Science Foundation of China(Grant No.61835014 and 51425206)+1 种基金the National Key Research Project(Grant No.2016YFB0402104)the Youth Innovation Promotion Association of CAS(Grant No.2012305).
文摘A new complex alkaline-earth metal borosilicate chloride Ba_(3)Ca4(BO_(3))_(3)(SiO4)Cl has been successfully synthesized by the high-temperature solution method.It crystallizes in the space group P6_(3)mc(no.186)of the hexagonal system.
基金supported by the National Natural Science Foundation of China(21771179,21571020 and 21301175)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB20010200)the support from“Chunmiao Projects”of Haixi Institute of Chinese Academy of Sciences.
文摘The search for new non-centrosymmetric(NCS)crystals with wide energy-gaps(Eg)and strong secondharmonic generation(SHG)responses has become one of the greatest challenges in the mid-and farinfrared(MFIR)nonlinear optical(NLO)field.In this work,a novel quaternary NCS material Sr_(5)ZnGa_(6)S_(15)(SZGS),which contains a complex 3D anionic framework and possesses the optical properties required for the MFIR NLO applications,especially the good balance between wide Eg(3.15 eV)and large SHG response(d_(ij)=1.2×AgGaS_(2)),has been discovered for the first time.Moreover,the result of theoretical calculation further indicates that the 3D[ZnGa_(6)S_(15)]^(10−)framework makes definitive contributions to the NLO properties.All these studies demonstrate that SZGS is a promising NLO candidate in the MFIR region.
文摘We define an m-involution to be a matrix K ∈ Cn×n for which Km -= I. In this article, we investigate the class Sm （A） of m-involutions that commute with a diagonalizable matrix A E Cn×n. A number of basic properties of Sm （A） and its related subclass Sm （A, X） are given, where X is an eigenvector matrix of A. Among them, Sm （A） is shown to have a torsion group structure under matrix multiplication if A has distinct eigenvalues and has non-denumerable cardinality otherwise. The constructive definition of Sm （A, X） allows one to generate all m-involutions commuting with a matrix with distinct eigenvalues. Some related results are also given for the class S,, （A） of m-involutions that anti-commute with a matrix A ∈ Cnn×n.
文摘The title compound, 〔NH 4〕 6〔(CH 3CO) 2(Mo 8O 28 )〕·4H 2O, was produced from (NH 4) 6〔Mo 7O 24 〕·4H 2O aqueous solution in the presence of N 2H 4·H 2SO 4 and its structure has been determined by X ray single crystal analysis. The crystallographic data: C 4H 38 Mo 8N 6O 34 , M r =1481.92, triclinic, P1, a=8.127(2), b = 10\^373(2), c = 12.383(3) , α=99.51(3), β=105.47(3), γ=112.92(3)°, V=883.0(3) 3, Z=1, D c =2.787g/cm 3, F(000)= 712, μ =2.864 mm -1 , Final R =0.0368 and wR =0.0924 for 2926 reflections with I】2σ(I ). The X ray crystal structure analysis reveals that there is one independent molecule in the unit cell of the title compound which contains one centrosymmetric diacetyloctamolybdate anion, six ammonium cations and four water molecules.
