Atomic-scale doping strategies and structure design play pivotal roles in tailoring the electronic structure and physicochemical property of electromagnetic wave absorption(EMWA)materials.However,the relationship betw...Atomic-scale doping strategies and structure design play pivotal roles in tailoring the electronic structure and physicochemical property of electromagnetic wave absorption(EMWA)materials.However,the relationship between configuration and electromagnetic(EM)loss mechanism has remained elusive.Herein,drawing inspiration from the DNA transcription process,we report the successful synthesis of novel in situ Mn/N co-doped helical carbon nanotubes with ultrabroad EMWA capability.Theoretical calculation and EM simulation confirm that the orbital coupling and spin polarization of the Mn–N4–C configuration,along with cross polarization generated by the helical structure,endow the helical converters with enhanced EM loss.As a result,HMC-8 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.13 dB at an ultralow thickness of 1.29 mm.Through precise tuning of the graphite domain size,HMC-7 achieves an effective absorption bandwidth(EAB)of 6.08 GHz at 2.02 mm thickness.Furthermore,constructing macroscale gradient metamaterials enables an ultrabroadband EAB of 12.16 GHz at a thickness of only 5.00 mm,with the maximum radar cross section reduction value reaching 36.4 dB m2.This innovative approach not only advances the understanding of metal–nonmetal co-doping but also realizes broadband EMWA,thus contributing to the development of EMWA mechanisms and applications.展开更多
Due to their potential use in creating advanced electronic textiles for wearable technology,functional fibers have garnered enormous interests.The presence of stretchable smart fibers has significantly expanded the ap...Due to their potential use in creating advanced electronic textiles for wearable technology,functional fibers have garnered enormous interests.The presence of stretchable smart fibers has significantly expanded the application scenarios of intelligent fibers.However,preparing fibers that possess both excellent electrical performance and high stretchability remains a formidable challenge.The fabrication of stretchable multifunctional fiber-based sensors employing a scalable method is reported here.Using a thermal drawing process,the collaborative interplay between the hollow confined channels of superelastic poly(styrene-b-(ethylene-co-butylene)-b-styrene)(SEBS)thermally drawn fibers and the high fluidity of liquid metal(LM)ensures the exceptional electrical performance of the fibers.Simultaneously,the presence of a helical structure further enhances both the sensing and mechanical properties.The helical two LM channel fiber-based sensors are capable of displaying more than 1000%strain,high stability over 1000 cycles,a quick pressure response and release time of 30.45 and 45.35 ms,and outstanding electrical conductivity of 8.075×10^(5)S/m.In addition,the electrical conductivity of this fiber increases with strain level,reaching 3×10^(6)S/m when the strain is 500%.Furthermore,due to their superior tension and compression sensing capabilities,flexible helical sensors offer considerable potential for use in wearable electronics applications such as human motion detection,Morse code compilation,multichannel sensing,and more.展开更多
The formation mechanism and stability of konjac glucomannan （KGM） helical structure were investigated by molecular dynamic simulation and experimental method. The results indicate that the molecular conformation of ...The formation mechanism and stability of konjac glucomannan （KGM） helical structure were investigated by molecular dynamic simulation and experimental method. The results indicate that the molecular conformation of KGM is a non-typical helical structure. In detail, helical structure of KGM is mainly sustained by acetyl group, whose size and stability are affected by the molecular polymerization degree of KGM. In vacuum among the non-bonding interactions, electrostatic force is the greatest factor affecting its helical structure, but in water solution, hydrogen bond affects the helical arrangement greatly. To our interest, temperature exhibits a reversible destroying effect to some extent; the helical structure will disappear completely and present a ruleless clew-like arrangement till 341 K. This work suggests that the method of combining molecular dynamic simulation and experiment tools can be effective in the study of KGM helical structure.展开更多
The appendages of mantis shrimp often bear bending loads from different directions during the in the process of preying on prey with its grazing limb.Hence,it has excellent bending resistance and isotropy to confront ...The appendages of mantis shrimp often bear bending loads from different directions during the in the process of preying on prey with its grazing limb.Hence,it has excellent bending resistance and isotropy to confront complex and changeable external load.The outstanding performance owes to the helical Bouligand structure with a certain interlayer corner,which is also widely found in other natural materials.Hence,the bio-inspired materials with basalt fiber are fabricated with outstanding bending resistance,isotropy and toughness.The research shows laminates with 18°interlayer corners exhibit relatively excellent bending resistance and isotropy,and the laminate with 11.25°interlayer corner has best toughness.Compared with traditional composites,average bending strength along different loading direction of bio-inspired materials increased by 28%,and anisotropy decreased by 86%.Besides,the maximum toughness of laminates can increase to 1.7 times of the original.Following the introduction of interlayer corners,the bio-inspired composite tends to be isotropic.To explore the reason for the change of the isotropic performance caused by diverse interlayer corners,the Finite Element Analysis based on classical laminate theory and Tsai–Wu and Tsai–Hill failure criterion.Besides,further experiments and observations are conducted to explore possible reasons.In conclusion,following the introduction of interlayer corners,the bio-inspired composites tend to be isotropic.This bio-inspired composites are expected to be applied to various complex modern engineering fields,such as vehicle,rail transit and aerospace.展开更多
An enantiopure helical coordination polymer AgPF6·（R）-3 as crystalline solid was synthesized by the self-assembly of chiral binaphthyl-based ligand（R）-6,6＇-di[6-（2,2＇-bipyridyl）]-2,2＇-diethoxyl-1,1＇-bin...An enantiopure helical coordination polymer AgPF6·（R）-3 as crystalline solid was synthesized by the self-assembly of chiral binaphthyl-based ligand（R）-6,6＇-di[6-（2,2＇-bipyridyl）]-2,2＇-diethoxyl-1,1＇-binaphthalene [（R）-3] and Ag＋ ion.The single crystal structural analysis indicates that this polymer exhibits an infinite cylindric single-stranded M-helical structure with local Λ configuration at each tetrahedral metal center.However,the extended structure is dissociated into some oligomeric fragments in solution.The 1H NMR spectra of complex AgPF6·（R）-3 show that the ligand possesses a good C2 symmetry,and the chemical shifts of the protons depend on the concentration and temperature.In addition,there are rapid dynamic exchanges among some oligonuclear fragments in the solution of AgPF6·（R）-3.展开更多
The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional c...The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional constraints on the motion of chain segments of the glassy liquid crystal and then further stabilized the molecule arrangement. A cholesteric liquid crystal film with stable optical properties was developed by this method.展开更多
5-（Hydroxymethyl） isophthalic acid （H2HIA） as a novel organic ligand was prepared from 3,5-bis（methoxycarbonyl）benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold inter...5-（Hydroxymethyl） isophthalic acid （H2HIA） as a novel organic ligand was prepared from 3,5-bis（methoxycarbonyl）benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold interpenetration structure, namely [Zn1/2（HIA）1/2（DPEE）1/2]n （1）, was hydrothermally synthesized at 160 ℃, using H2HIA ligands to assemble with DPEE ligands and Zn2＋ ions. Complex 1 crystalizes in orthorhombic system, space group Pnna, with a = 8.2118（5）, b = 17.1698（7）, c =14.9922（7） ？, V = 2113.82（18） ？3, μ = 1.194 mm-1, Z = 4 and S = 0.967. Moreover, some physical characteristics of complex 1, such as powder X-ray diffraction （PXRD）, thermogravimetry analyses （TGA） and photoluminescent properties, were also investigated.展开更多
Reactions of 2-（2-benzoimidazolyl）acetonitrile and Na N3 with Zn SO4 or Zn Cl2 in the presence of nicotinic acid in the mixture of Et OH/H2 O afforded a mononuclear compound [Zn（L1）2]（1） and a 1-D polymer [Zn（L...Reactions of 2-（2-benzoimidazolyl）acetonitrile and Na N3 with Zn SO4 or Zn Cl2 in the presence of nicotinic acid in the mixture of Et OH/H2 O afforded a mononuclear compound [Zn（L1）2]（1） and a 1-D polymer [Zn（L1）Cl]n（2）, respectively（L1 = 5-[（benzoimidazolyl）methyl]-1H-tetrazolate）. However, in the similar condition except that imidazole was added instead of nicotinic acid, the reaction afforded a 1-D compound [Zn（L1）2]n（3） featuring triply helical chains via the π-π stacking of ligands. They are characterized by elemental analysis and IR, and their structures have been determined by X-ray crystallography. Thermal stability of these compounds was measured by TGA and their luminescent properties were investigated at room temperature.展开更多
A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esteri...A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esterification of L-(-)-2.3-O-methylidene threitol and L-(+)-2,3-O-isopropplidene threitol with alkanedioyl dichlorides and o-,m-,and p-phthaloyl dichlorides.展开更多
NiTi alloy lattice structures are crucial for reusable energy absorption due to their shape memory effects.However,existing NiTi alloy lattice structures always suffer from localized deformation bands during loading,c...NiTi alloy lattice structures are crucial for reusable energy absorption due to their shape memory effects.However,existing NiTi alloy lattice structures always suffer from localized deformation bands during loading,causing local strains to exceed the recoverable strain limit of the alloy and significantly reducing their reusable energy-absorbing capacity.In this study,we developed a NiTi alloy helical lattice structure(HLS)to effectively prevent localized deformation bands.This is attributed to its struts distributing stress and strain uniformly through torsional deformation,thereby alleviating local stress concentrations and suppressing the formation of localized deformation bands.Additionally,its unit cells provide mutual support and reinforcement during deformation,effectively preventing the progression of localized deformation bands.The NiTi alloy HLS exhibits superior reusable energy absorption compared to previously reported reusable energy-absorbing materials/structures and enhanced damage tolerance under large compression strain.This study provides valuable insights for the development of high-performance reusable NiTi alloy energy-absorbing lattice structures.展开更多
In this work, the formation sites, helical parameters and hydrogen bond positions of Konjac glucomannan molecular helices were investigated using molecular dynamic simulation method. To our interest, the KGM chain is ...In this work, the formation sites, helical parameters and hydrogen bond positions of Konjac glucomannan molecular helices were investigated using molecular dynamic simulation method. To our interest, the KGM chain is mainly composed by local left and right helix struetttres. The formation sites of KGM chain might locate at the chain-segments containing acetyl groups, and the left helix is the favorable conformation of KGM. Temperature-dependent molecule conformation study indicates that the right helix is dominant when the temperature is lower than 343 K, above which, however, the left helix is dominating （right helix disappears）. In addition, intramolecular hydrogen bonds in the left helix can be found at the -OH groups on C（2）, C（4） and C（6） of mannose residues; comparably, the intramolecular hydrogen bonds in the right helix can be mainly observed at the -OH groups on C（4） and C（6） of the mannose residues and C（3） of the glucose residues. In conclusion, molecular dynamic simulation is an efficient method for the microscopic conformation study of glucomannan molecular helices.展开更多
A new metal-organic framework based on bbi and PHBA（bbi = 1,1＇-（1, 4-butanediyl）bis（imidazole）, PHBA = p-hydroxybenzoic acid）, namely, [Cd（bbi）（PHBA）2]n（1） has been synthesized by the conventional method....A new metal-organic framework based on bbi and PHBA（bbi = 1,1＇-（1, 4-butanediyl）bis（imidazole）, PHBA = p-hydroxybenzoic acid）, namely, [Cd（bbi）（PHBA）2]n（1） has been synthesized by the conventional method. Compound 1 displays a two-dimensional（2D） layer structure possessing the left-and right-handed helical chains and stabilized by intermolecular hydrogen-bonding to form a three-dimensional（3D） supramolecular structure. Topologically, the 2D layer belongs to well-known（4,4） network topology. The structure has been determined by single-crystal X-ray diffraction analyses, and further characterized by infrared spectra（IR）, elemental analyses and powder X-ray diffraction. In addition, the thermal behavior and luminescent properties of [Cd（bbi）（PHBA）2]n have been investigated in detail.展开更多
The crystalline structures and crystallization behaviors of iPP containing β nucleation agent TMB-5 （iPP/TMB-5） were investigated by synchrotron radiation wide angel X-ray diffraction （SR-WAXD）, differential scan...The crystalline structures and crystallization behaviors of iPP containing β nucleation agent TMB-5 （iPP/TMB-5） were investigated by synchrotron radiation wide angel X-ray diffraction （SR-WAXD）, differential scanning calorimeter （DSC） and polarized light microscope （PLM）. It was found that α-crystallization lagged behind β-crystallization at normal temperatures, but the discrepancy reduced with increasing temperature. TMB-5 could not induce β-iPP when the nucleation agent is wrapped up with α-crystal that crystallized at high temperatures. The polymorphic composition of iPP/TMB-5 was susceptible to the introductory moment of shear. New crystallization process of β-nucleated iPP was proposed to understand the experimental phenomena which could not be explained by those reported in the literature. It was supposed that polymer crystallization initiated from mesophase, and the formations of iPP crystals involved the organization of helical conformation ordering within rnesophase. It was proposed that the iPP melt contained mesophases with stereocomplex-type ordering of right-handed and left-handed helical chains which could be disturbed by shear or TMB-5, leading to different polymorphic structures.展开更多
{[Cu_3（cis-DAM）_4（OH）_2]·12H_2O}_n 1 and [Ag_3（trans-DAM）_2（NO_3）]_n 2 with a flexible ligand N,NA-diacetic acid imidazolium（HDAM） were synthesized and characterized by single-crystal X-ray diffraction....{[Cu_3（cis-DAM）_4（OH）_2]·12H_2O}_n 1 and [Ag_3（trans-DAM）_2（NO_3）]_n 2 with a flexible ligand N,NA-diacetic acid imidazolium（HDAM） were synthesized and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic I222 space group with a = 12.033（2）,b = 12.498（3）,c = 14.963（3） A,V = 2250.4（8） A^3,Z = 8,C_7H_（13.5）N_2O_（7.5）Cu_（0.75）,M_r = 293.35,D_c = 1.732 g·cm^-3,F（000） = 1210,GOF = 1.087,the final R（I 〉 2σ（I）） = 0.0521 and w R（all data） = 0.1386. Compound 2 crystallizes in the monoclinic C2/c space group with a = 21.601（4）,b = 8.321（2）,c = 13.589（3） A,β = 126.95（3）°,V = 1951.9（7） A^3,Z = 8,C_7H_7N_（2.5）O_（5.5）Ag_（1.5）,M_r = 375.96,D_c = 2.559 g·cm^-3,F（000） = 1448,GOF = 1.017,R（I 〉 2σ（I）） = 0.0222 and w R（all data） = 0.0633. Compound 1 displays a novel 2D layer,consisting of a couple of left-helical chains with a pitch of 12.498（3） A formed by μ_3-cis-DAM~– ligands and Cu（1） ions,which are stabilized by hydrogen bonding interactions to give a 3D supramolecular framework. As for 2,Ag（1） ions are doubly bridged by trans-DAM~– and NO_3~– to form [Ag（1）_2O_4] chains,which are further connected by Ag（2） and trans-DAM~– to build a 3D framework. Additionally,thermogravimetric analyses,FT-IR spectroscopy,UV-visible spectroscopy,and the fluorescent properties were discussed.展开更多
Chiral supramolecules prepared by the additive-driven self-assembly of block copolymers provide a facile method to construct helical nanostructures. In this study, we investigated the chiral transfer from chiral tarta...Chiral supramolecules prepared by the additive-driven self-assembly of block copolymers provide a facile method to construct helical nanostructures. In this study, we investigated the chiral transfer from chiral tartaric acid to poly（styrene）-b-poly（ethylene oxide） using small-angle X-ray scattering,transmission electron microscopy, circular dichroism, and vibrational circular dichroism. The results showed that the chirality was transferred to both the segments of block copolymer irrespective of the interaction with the chiral additives and formation of helical phase structure. However, the chirality transfer was carried out using different methods： for poly（ethylene oxide） segments, the chirality transfer was carried out via direct hydrogen bond formation; for polystyrene segments, the chirality transfer was carried out via the cooperative motion of block copolymers during the thermal annealing.展开更多
There was phase separation between the anisotropic and isotropic phases in the ethyl-acetyl cellulose/dichloroacetic acid cholesteric liquid crystalline solutions .The textures of mesophase varied with the concentrati...There was phase separation between the anisotropic and isotropic phases in the ethyl-acetyl cellulose/dichloroacetic acid cholesteric liquid crystalline solutions .The textures of mesophase varied with the concentration. The mesophases could form the disc-like texture, oily streaks texture and texture of domains gathered randomly. In the first two textures the layers of the ordered molecular chain were perpendicular to the slide surface and the axes of the helical structure were parallel to the slide surface.展开更多
Based on the uniform,helical and spiral domain-wall magnetic configurations,the excited spin waves are studied with emphasis on the role of damping.We find that the damping closes the gap of dispersion,and greatly inf...Based on the uniform,helical and spiral domain-wall magnetic configurations,the excited spin waves are studied with emphasis on the role of damping.We find that the damping closes the gap of dispersion,and greatly influences the dispersion in the long-wave region for the spin waves of spiral wall and helical structure.For the uniform configuration,the Dzyaloshinskii-Moriya interaction determines the modification of dispersion by the damping.Furthermore,we investigate the interaction between spin waves and a moving spiral domain wall.In the presence of damping,the amplitude of spin wave can increase after running across the wall for small wave numbers.Driving by the spin waves,the wall propagates towards the spin-wave source with an increasing velocity.Unlike the case without damping,the relation between the wall velocity and the spin-wave frequency depends on the position of wall.展开更多
Correlation between the belieal structure and optical activity of two derivatives of R(+)- 1, 1'-binaphthyl-2,2'-diol was derived from a study of their optical rotations, CD curves and Xray crystal structures.
Nb_(3)Sn triple‐helical structure is the elementary structure in the superconducting cable of ITER magnets and undergoes prolonged fatigue loading in extreme environments leading to serious damage degradation.In this...Nb_(3)Sn triple‐helical structure is the elementary structure in the superconducting cable of ITER magnets and undergoes prolonged fatigue loading in extreme environments leading to serious damage degradation.In this paper,the fatigue behaviors of the Nb_(3)Sn triple‐helical structure have been investigated by the strain cycling fatigue experiments at liquid nitrogen temperature.The results indicate that Nb_(3)Sn triple‐helical structures with short twist‐pitches possess excellent fatigue damage resistance than that of long twist‐pitches,such as longer fatigue life,slower damage degradation,and smaller energy dissipation.Meanwhile,a theoretical model of damage evolution has been established to reveal the effects of twist‐pitches on fatigue properties for triplehelical structures,which is also validated by the present experimental data.Furthermore,one can see that the Nb_(3)Sn superconducting wires in a triple‐helical structure with the shorter twist‐pitches have a larger elongation of helical structure and less cyclic deformation,which can be considered as the main mechanism of better fatigue damage properties for the triple‐helical structures during the strain cycling processes.These findings provide a better understanding of the fatigue properties and damage mechanisms for Nb_(3)Sn triple‐helical structures in superconducting cables of ITER magnets.展开更多
A novel 1D copper（II） helical chain is constructed through the connection of tetranuclear copper（ll） units [Cu4（L）（Py）4] （H8L=N,N＇-（BINOL-3,3＇-dicarboxyl）-disalicylhydrazide, where BINOL is 1,l＇-binaphth...A novel 1D copper（II） helical chain is constructed through the connection of tetranuclear copper（ll） units [Cu4（L）（Py）4] （H8L=N,N＇-（BINOL-3,3＇-dicarboxyl）-disalicylhydrazide, where BINOL is 1,l＇-binaphthalenyl-2,2＇- diol, py=pyridine） by weak coordination-driven self-assembly, and characterized by IR, single crystal X-ray dif- fraction, thermogravimetric analysis, and X-ray power diffraction analysis. Interestingly, the helical chains are packed in an alternating left-（M） and right-handed （P） chirality, the orientation of the helices was determined by the axial chirality of the ligand. The complex shows antiferromagnetic interactions between the copper centers.展开更多
基金supported by the National Natural Science Foundation of China(22265021)the Aeronautical Science Foundation of China(2020Z056056003)Jiangxi Provincial Natural Science Foundation(20232BAB212004).
文摘Atomic-scale doping strategies and structure design play pivotal roles in tailoring the electronic structure and physicochemical property of electromagnetic wave absorption(EMWA)materials.However,the relationship between configuration and electromagnetic(EM)loss mechanism has remained elusive.Herein,drawing inspiration from the DNA transcription process,we report the successful synthesis of novel in situ Mn/N co-doped helical carbon nanotubes with ultrabroad EMWA capability.Theoretical calculation and EM simulation confirm that the orbital coupling and spin polarization of the Mn–N4–C configuration,along with cross polarization generated by the helical structure,endow the helical converters with enhanced EM loss.As a result,HMC-8 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.13 dB at an ultralow thickness of 1.29 mm.Through precise tuning of the graphite domain size,HMC-7 achieves an effective absorption bandwidth(EAB)of 6.08 GHz at 2.02 mm thickness.Furthermore,constructing macroscale gradient metamaterials enables an ultrabroadband EAB of 12.16 GHz at a thickness of only 5.00 mm,with the maximum radar cross section reduction value reaching 36.4 dB m2.This innovative approach not only advances the understanding of metal–nonmetal co-doping but also realizes broadband EMWA,thus contributing to the development of EMWA mechanisms and applications.
基金the National Natural Science Foundation of China(No.52173059)the National Key Research and Development Program of China(No.2022YFB3805803)+1 种基金the Key Research and Development Program of Jiangsu Province(No.21KJA540002)China National Textile and Apparel Council Science and Technology Guidance Project(No.2020116).
文摘Due to their potential use in creating advanced electronic textiles for wearable technology,functional fibers have garnered enormous interests.The presence of stretchable smart fibers has significantly expanded the application scenarios of intelligent fibers.However,preparing fibers that possess both excellent electrical performance and high stretchability remains a formidable challenge.The fabrication of stretchable multifunctional fiber-based sensors employing a scalable method is reported here.Using a thermal drawing process,the collaborative interplay between the hollow confined channels of superelastic poly(styrene-b-(ethylene-co-butylene)-b-styrene)(SEBS)thermally drawn fibers and the high fluidity of liquid metal(LM)ensures the exceptional electrical performance of the fibers.Simultaneously,the presence of a helical structure further enhances both the sensing and mechanical properties.The helical two LM channel fiber-based sensors are capable of displaying more than 1000%strain,high stability over 1000 cycles,a quick pressure response and release time of 30.45 and 45.35 ms,and outstanding electrical conductivity of 8.075×10^(5)S/m.In addition,the electrical conductivity of this fiber increases with strain level,reaching 3×10^(6)S/m when the strain is 500%.Furthermore,due to their superior tension and compression sensing capabilities,flexible helical sensors offer considerable potential for use in wearable electronics applications such as human motion detection,Morse code compilation,multichannel sensing,and more.
基金supported by the National Natural Science Foundation of China (30871749, 30901004) the Natural Science Foundation of Fujian Province (2009J01061)
文摘The formation mechanism and stability of konjac glucomannan （KGM） helical structure were investigated by molecular dynamic simulation and experimental method. The results indicate that the molecular conformation of KGM is a non-typical helical structure. In detail, helical structure of KGM is mainly sustained by acetyl group, whose size and stability are affected by the molecular polymerization degree of KGM. In vacuum among the non-bonding interactions, electrostatic force is the greatest factor affecting its helical structure, but in water solution, hydrogen bond affects the helical arrangement greatly. To our interest, temperature exhibits a reversible destroying effect to some extent; the helical structure will disappear completely and present a ruleless clew-like arrangement till 341 K. This work suggests that the method of combining molecular dynamic simulation and experiment tools can be effective in the study of KGM helical structure.
基金This work was supported by the National Key Research and Development Program of China(No.2018YFA0703300)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)+5 种基金National Natural Science Foundation of China(No.51835006,51875244,U19A20103)Program for JLU Science and Technology Innovative Research Team(No.2020TD-03)the Natural Science Foundation of Jilin Province(No.20200201232JC)Graduate innovation research program of Jilin University(101832020CX161)Interdisciplinary Integration and Innovation Project of JLU(No.JLUXKJC2021ZZ03)supported by“Fundamental Research Funds for the Central Universities”.
文摘The appendages of mantis shrimp often bear bending loads from different directions during the in the process of preying on prey with its grazing limb.Hence,it has excellent bending resistance and isotropy to confront complex and changeable external load.The outstanding performance owes to the helical Bouligand structure with a certain interlayer corner,which is also widely found in other natural materials.Hence,the bio-inspired materials with basalt fiber are fabricated with outstanding bending resistance,isotropy and toughness.The research shows laminates with 18°interlayer corners exhibit relatively excellent bending resistance and isotropy,and the laminate with 11.25°interlayer corner has best toughness.Compared with traditional composites,average bending strength along different loading direction of bio-inspired materials increased by 28%,and anisotropy decreased by 86%.Besides,the maximum toughness of laminates can increase to 1.7 times of the original.Following the introduction of interlayer corners,the bio-inspired composite tends to be isotropic.To explore the reason for the change of the isotropic performance caused by diverse interlayer corners,the Finite Element Analysis based on classical laminate theory and Tsai–Wu and Tsai–Hill failure criterion.Besides,further experiments and observations are conducted to explore possible reasons.In conclusion,following the introduction of interlayer corners,the bio-inspired composites tend to be isotropic.This bio-inspired composites are expected to be applied to various complex modern engineering fields,such as vehicle,rail transit and aerospace.
基金Supported by the National Natural Science Foundation of China(No.20502024)
文摘An enantiopure helical coordination polymer AgPF6·（R）-3 as crystalline solid was synthesized by the self-assembly of chiral binaphthyl-based ligand（R）-6,6＇-di[6-（2,2＇-bipyridyl）]-2,2＇-diethoxyl-1,1＇-binaphthalene [（R）-3] and Ag＋ ion.The single crystal structural analysis indicates that this polymer exhibits an infinite cylindric single-stranded M-helical structure with local Λ configuration at each tetrahedral metal center.However,the extended structure is dissociated into some oligomeric fragments in solution.The 1H NMR spectra of complex AgPF6·（R）-3 show that the ligand possesses a good C2 symmetry,and the chemical shifts of the protons depend on the concentration and temperature.In addition,there are rapid dynamic exchanges among some oligonuclear fragments in the solution of AgPF6·（R）-3.
基金This work was financially supported by the National High-Tech Research and Development Program of China (No. 2003AA327050).
文摘The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional constraints on the motion of chain segments of the glassy liquid crystal and then further stabilized the molecule arrangement. A cholesteric liquid crystal film with stable optical properties was developed by this method.
基金supported by the Natural Science Foundation of Guizhou Province(20122344)125 program of Guizhou Education Department(2012015)the Doctoral Scientific Fund of Zunyi Normal College(2012BSJJ12)
文摘5-（Hydroxymethyl） isophthalic acid （H2HIA） as a novel organic ligand was prepared from 3,5-bis（methoxycarbonyl）benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold interpenetration structure, namely [Zn1/2（HIA）1/2（DPEE）1/2]n （1）, was hydrothermally synthesized at 160 ℃, using H2HIA ligands to assemble with DPEE ligands and Zn2＋ ions. Complex 1 crystalizes in orthorhombic system, space group Pnna, with a = 8.2118（5）, b = 17.1698（7）, c =14.9922（7） ？, V = 2113.82（18） ？3, μ = 1.194 mm-1, Z = 4 and S = 0.967. Moreover, some physical characteristics of complex 1, such as powder X-ray diffraction （PXRD）, thermogravimetry analyses （TGA） and photoluminescent properties, were also investigated.
基金supported by the National Natural Science Foundation of China(21201023)the scientific research fund of Hubei Provincial Education Department(D20131202)
文摘Reactions of 2-（2-benzoimidazolyl）acetonitrile and Na N3 with Zn SO4 or Zn Cl2 in the presence of nicotinic acid in the mixture of Et OH/H2 O afforded a mononuclear compound [Zn（L1）2]（1） and a 1-D polymer [Zn（L1）Cl]n（2）, respectively（L1 = 5-[（benzoimidazolyl）methyl]-1H-tetrazolate）. However, in the similar condition except that imidazole was added instead of nicotinic acid, the reaction afforded a 1-D compound [Zn（L1）2]n（3） featuring triply helical chains via the π-π stacking of ligands. They are characterized by elemental analysis and IR, and their structures have been determined by X-ray crystallography. Thermal stability of these compounds was measured by TGA and their luminescent properties were investigated at room temperature.
文摘A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esterification of L-(-)-2.3-O-methylidene threitol and L-(+)-2,3-O-isopropplidene threitol with alkanedioyl dichlorides and o-,m-,and p-phthaloyl dichlorides.
基金financially supported by the National Key R&D Program of China(No.2022YFB4600500)the National Safety Academic Fund(Nos.U2130201 and U2330105).
文摘NiTi alloy lattice structures are crucial for reusable energy absorption due to their shape memory effects.However,existing NiTi alloy lattice structures always suffer from localized deformation bands during loading,causing local strains to exceed the recoverable strain limit of the alloy and significantly reducing their reusable energy-absorbing capacity.In this study,we developed a NiTi alloy helical lattice structure(HLS)to effectively prevent localized deformation bands.This is attributed to its struts distributing stress and strain uniformly through torsional deformation,thereby alleviating local stress concentrations and suppressing the formation of localized deformation bands.Additionally,its unit cells provide mutual support and reinforcement during deformation,effectively preventing the progression of localized deformation bands.The NiTi alloy HLS exhibits superior reusable energy absorption compared to previously reported reusable energy-absorbing materials/structures and enhanced damage tolerance under large compression strain.This study provides valuable insights for the development of high-performance reusable NiTi alloy energy-absorbing lattice structures.
基金supported by the National Natural Science Foundation of China (30871749,30901004)Natural Science Foundation of Fujian Province(2009J01061)
文摘In this work, the formation sites, helical parameters and hydrogen bond positions of Konjac glucomannan molecular helices were investigated using molecular dynamic simulation method. To our interest, the KGM chain is mainly composed by local left and right helix struetttres. The formation sites of KGM chain might locate at the chain-segments containing acetyl groups, and the left helix is the favorable conformation of KGM. Temperature-dependent molecule conformation study indicates that the right helix is dominant when the temperature is lower than 343 K, above which, however, the left helix is dominating （right helix disappears）. In addition, intramolecular hydrogen bonds in the left helix can be found at the -OH groups on C（2）, C（4） and C（6） of mannose residues; comparably, the intramolecular hydrogen bonds in the right helix can be mainly observed at the -OH groups on C（4） and C（6） of the mannose residues and C（3） of the glucose residues. In conclusion, molecular dynamic simulation is an efficient method for the microscopic conformation study of glucomannan molecular helices.
基金Supported by the Science and Technology Development Plan of Jilin Province(20150520006JH)Science and Technology Research Project of Education Department of Jilin Province(2016219)Science and Technology Development Plan of Siping City(2013055)
文摘A new metal-organic framework based on bbi and PHBA（bbi = 1,1＇-（1, 4-butanediyl）bis（imidazole）, PHBA = p-hydroxybenzoic acid）, namely, [Cd（bbi）（PHBA）2]n（1） has been synthesized by the conventional method. Compound 1 displays a two-dimensional（2D） layer structure possessing the left-and right-handed helical chains and stabilized by intermolecular hydrogen-bonding to form a three-dimensional（3D） supramolecular structure. Topologically, the 2D layer belongs to well-known（4,4） network topology. The structure has been determined by single-crystal X-ray diffraction analyses, and further characterized by infrared spectra（IR）, elemental analyses and powder X-ray diffraction. In addition, the thermal behavior and luminescent properties of [Cd（bbi）（PHBA）2]n have been investigated in detail.
基金supported by the National Natural Science Foundation of China(Nos.51573131,51173130,21274149 and 21374077)
文摘The crystalline structures and crystallization behaviors of iPP containing β nucleation agent TMB-5 （iPP/TMB-5） were investigated by synchrotron radiation wide angel X-ray diffraction （SR-WAXD）, differential scanning calorimeter （DSC） and polarized light microscope （PLM）. It was found that α-crystallization lagged behind β-crystallization at normal temperatures, but the discrepancy reduced with increasing temperature. TMB-5 could not induce β-iPP when the nucleation agent is wrapped up with α-crystal that crystallized at high temperatures. The polymorphic composition of iPP/TMB-5 was susceptible to the introductory moment of shear. New crystallization process of β-nucleated iPP was proposed to understand the experimental phenomena which could not be explained by those reported in the literature. It was supposed that polymer crystallization initiated from mesophase, and the formations of iPP crystals involved the organization of helical conformation ordering within rnesophase. It was proposed that the iPP melt contained mesophases with stereocomplex-type ordering of right-handed and left-handed helical chains which could be disturbed by shear or TMB-5, leading to different polymorphic structures.
基金supported by Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2013152)the Doctoral Scientific Research Foundation of Yuncheng University(No.YQ-2014019)
文摘{[Cu_3（cis-DAM）_4（OH）_2]·12H_2O}_n 1 and [Ag_3（trans-DAM）_2（NO_3）]_n 2 with a flexible ligand N,NA-diacetic acid imidazolium（HDAM） were synthesized and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic I222 space group with a = 12.033（2）,b = 12.498（3）,c = 14.963（3） A,V = 2250.4（8） A^3,Z = 8,C_7H_（13.5）N_2O_（7.5）Cu_（0.75）,M_r = 293.35,D_c = 1.732 g·cm^-3,F（000） = 1210,GOF = 1.087,the final R（I 〉 2σ（I）） = 0.0521 and w R（all data） = 0.1386. Compound 2 crystallizes in the monoclinic C2/c space group with a = 21.601（4）,b = 8.321（2）,c = 13.589（3） A,β = 126.95（3）°,V = 1951.9（7） A^3,Z = 8,C_7H_7N_（2.5）O_（5.5）Ag_（1.5）,M_r = 375.96,D_c = 2.559 g·cm^-3,F（000） = 1448,GOF = 1.017,R（I 〉 2σ（I）） = 0.0222 and w R（all data） = 0.0633. Compound 1 displays a novel 2D layer,consisting of a couple of left-helical chains with a pitch of 12.498（3） A formed by μ_3-cis-DAM~– ligands and Cu（1） ions,which are stabilized by hydrogen bonding interactions to give a 3D supramolecular framework. As for 2,Ag（1） ions are doubly bridged by trans-DAM~– and NO_3~– to form [Ag（1）_2O_4] chains,which are further connected by Ag（2） and trans-DAM~– to build a 3D framework. Additionally,thermogravimetric analyses,FT-IR spectroscopy,UV-visible spectroscopy,and the fluorescent properties were discussed.
基金supported by National Natural Science foundation of China(Nos.21374060 and 21574081)
文摘Chiral supramolecules prepared by the additive-driven self-assembly of block copolymers provide a facile method to construct helical nanostructures. In this study, we investigated the chiral transfer from chiral tartaric acid to poly（styrene）-b-poly（ethylene oxide） using small-angle X-ray scattering,transmission electron microscopy, circular dichroism, and vibrational circular dichroism. The results showed that the chirality was transferred to both the segments of block copolymer irrespective of the interaction with the chiral additives and formation of helical phase structure. However, the chirality transfer was carried out using different methods： for poly（ethylene oxide） segments, the chirality transfer was carried out via direct hydrogen bond formation; for polystyrene segments, the chirality transfer was carried out via the cooperative motion of block copolymers during the thermal annealing.
基金Projects supported by the Science Fund of the Chinese Academy of Sciences.
文摘There was phase separation between the anisotropic and isotropic phases in the ethyl-acetyl cellulose/dichloroacetic acid cholesteric liquid crystalline solutions .The textures of mesophase varied with the concentration. The mesophases could form the disc-like texture, oily streaks texture and texture of domains gathered randomly. In the first two textures the layers of the ordered molecular chain were perpendicular to the slide surface and the axes of the helical structure were parallel to the slide surface.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61774001 and 51972103)the Natural Science Foundation of Hebei Province of China(Grant No.F2019202141)the Fund of the State Key Laboratory of Quantum Optics and Quantum Optics Devices,Shanxi University,China(Grant No.KF201906).
文摘Based on the uniform,helical and spiral domain-wall magnetic configurations,the excited spin waves are studied with emphasis on the role of damping.We find that the damping closes the gap of dispersion,and greatly influences the dispersion in the long-wave region for the spin waves of spiral wall and helical structure.For the uniform configuration,the Dzyaloshinskii-Moriya interaction determines the modification of dispersion by the damping.Furthermore,we investigate the interaction between spin waves and a moving spiral domain wall.In the presence of damping,the amplitude of spin wave can increase after running across the wall for small wave numbers.Driving by the spin waves,the wall propagates towards the spin-wave source with an increasing velocity.Unlike the case without damping,the relation between the wall velocity and the spin-wave frequency depends on the position of wall.
文摘Correlation between the belieal structure and optical activity of two derivatives of R(+)- 1, 1'-binaphthyl-2,2'-diol was derived from a study of their optical rotations, CD curves and Xray crystal structures.
基金supported by the National Natural Science Foundation of China(Nos.12232005,U2241267)the Natural Science Foundation of Gansu Province of China(No.23JRRA1118).
文摘Nb_(3)Sn triple‐helical structure is the elementary structure in the superconducting cable of ITER magnets and undergoes prolonged fatigue loading in extreme environments leading to serious damage degradation.In this paper,the fatigue behaviors of the Nb_(3)Sn triple‐helical structure have been investigated by the strain cycling fatigue experiments at liquid nitrogen temperature.The results indicate that Nb_(3)Sn triple‐helical structures with short twist‐pitches possess excellent fatigue damage resistance than that of long twist‐pitches,such as longer fatigue life,slower damage degradation,and smaller energy dissipation.Meanwhile,a theoretical model of damage evolution has been established to reveal the effects of twist‐pitches on fatigue properties for triplehelical structures,which is also validated by the present experimental data.Furthermore,one can see that the Nb_(3)Sn superconducting wires in a triple‐helical structure with the shorter twist‐pitches have a larger elongation of helical structure and less cyclic deformation,which can be considered as the main mechanism of better fatigue damage properties for the triple‐helical structures during the strain cycling processes.These findings provide a better understanding of the fatigue properties and damage mechanisms for Nb_(3)Sn triple‐helical structures in superconducting cables of ITER magnets.
基金This work was supported by the National Natural Science Foundation of China （No. 20971029） and Guangxi Natural Science Foundation （Nos. 2010GXNSFD013018,2010GXNSFF013001）
文摘A novel 1D copper（II） helical chain is constructed through the connection of tetranuclear copper（ll） units [Cu4（L）（Py）4] （H8L=N,N＇-（BINOL-3,3＇-dicarboxyl）-disalicylhydrazide, where BINOL is 1,l＇-binaphthalenyl-2,2＇- diol, py=pyridine） by weak coordination-driven self-assembly, and characterized by IR, single crystal X-ray dif- fraction, thermogravimetric analysis, and X-ray power diffraction analysis. Interestingly, the helical chains are packed in an alternating left-（M） and right-handed （P） chirality, the orientation of the helices was determined by the axial chirality of the ligand. The complex shows antiferromagnetic interactions between the copper centers.
