Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'...Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.展开更多
As a new addition to lightweight composite structures,the sandwich cylindrical shell with a metallic wire mesh core has emerged as a promising solution for thermodynamic performance analysis at elevated temperatures.T...As a new addition to lightweight composite structures,the sandwich cylindrical shell with a metallic wire mesh core has emerged as a promising solution for thermodynamic performance analysis at elevated temperatures.The intricate interwoven cellular formations within the metallic wire mesh pose difficulties for thermo-mechanical modeling and property evaluation.First,the constitutive models employed to characterize hysteresis phenomena were presented,comprising isotropic elasticity,Bergstrom-Boyce model,Ogden hyper-elasticity,and parameter identification through mechanical examinations at varying temperatures.Second,the finite element modeling of cylindrical shell structures was determined for modal and steady-state dynamic analyses.Third,the experimental procedures were carried out,including the preparation of the sandwich cylindrical shell and the dynamic testing platform.The first-order natural frequency of the cylindrical shell structure is close to the resonance frequency of the dynamic test results,with a maximum error of 6.5%,demonstrating the accuracy of the simulation model.When compared to the solid-core cylindrical shell,the average insertion loss of the sandwich cylindrical shell structure within the frequency range of 10–1000 Hz at room temperature is up to 11.09 dB.Furthermore,at elevated temperatures,the average insertion loss of the sandwich cylindrical shell decreases but fluctuates as the temperature changes.展开更多
Herein,nanosized Hf_(6)Ta_(2)O_(17) encapsulated graphite flakes were firstly constructed using the sol-gel method,then deposited on the surface of carbon/carbon(C/C)composites by plasma spraying technique to prolong ...Herein,nanosized Hf_(6)Ta_(2)O_(17) encapsulated graphite flakes were firstly constructed using the sol-gel method,then deposited on the surface of carbon/carbon(C/C)composites by plasma spraying technique to prolong their service span in critical environments.Nanoindentation results affirmed the active influ-ence of graphite flakes on elevating the toughness of the Hf_(6)Ta_(2)O_(17) coating.Besides,after being exposed to the oxyacetylene torch with a peak temperature of about 2000℃,the sample achieved near zero ab-lation(0.06 mg/s),meanwhile its porosity and mass ablation rate showed 39.5%and 60.0%reduction when compared to pure Hf_(6)Ta_(2)O_(17) sample.During exposure,the external Hf_(6)Ta_(2)O_(17) served as an oxy-gen barrier for internal graphite flakes,inversely internal graphite flakes provided a“pinning”effect on external Hf_(6)Ta_(2)O_(17),which accounted for its exceptional ablation performance.This work offers a new insight into the design of surface modification of C/C composites and other high-temperature structural materials.展开更多
Precast concrete structures have gained popularity due to their advantages.However,the seismic performance of their connection joints remains an area of ongoing research and improvement.Grouted Sleeve Connection(GSC)o...Precast concrete structures have gained popularity due to their advantages.However,the seismic performance of their connection joints remains an area of ongoing research and improvement.Grouted Sleeve Connection(GSC)offers a solution for connecting reinforcements in precast components,but their vulnerability to internal defects,such as construction errors and material variability,can significantly impact performance.This article presents a finite element analysis(FEA)to evaluate the impact of internal grouting defects in GSC on the structural performance of precast reinforced concrete columns.Four finite elementmodels representing GSC with varying degrees of defects were used to investigate the effects on mechanical properties,including bearing capacity,stress-deformation behavior,and stiffness degradation.The study highlights the significant impact of internal grouting defects on the mechanical performance of GSC,with findings indicating a decrease in stiffness,increased plastic deformation,and reduced energy dissipation as the proportion of internal defects rises.The analysis reveals that the internal defects in GSC act as stress concentration points,leading to early crack formation and accelerated damage under cyclic loading.By improving construction quality and reducing the prevalence of grouting defects,the adverse effects on the performance of GSC can be mitigated.Compared to defect-free specimens,those with defects of 30%exhibited a 31.23%reduction in horizontal bearing capacity,highlighting the importance of minimizing defects in practical engineering applications.展开更多
Erythromycin thiocyanate is widely used for the production of other macrolide antibiotics. In this work, a novel heterosolvate of this pharmaceutical compound has been obtained and characterized for the first time, wh...Erythromycin thiocyanate is widely used for the production of other macrolide antibiotics. In this work, a novel heterosolvate of this pharmaceutical compound has been obtained and characterized for the first time, which was transformed from the dihydrate form in the acetone solvent through evaporation crystallization. Thermal behavior together with compositional analysis revealed that both water and acetone molecules participated in the formation of the crystal lattice which is rarely reported before. The general chemical name of the heterosolvate may be defined as erythromycin thiocyanate sesquihydrate hemiacetonate. Furthermore, studies on solid-state spectral analysis provided strong evidence of intermolecular hydrogen bonds in heterosolvate crystals. According to the crystal structure determined by single crystal X-ray diffraction, the formation mechanism of the heterosolvate is proposed in which strong multihydrogen bondings between water and solute molecules form the layer structure. While acetone molecules form single-hydrogen bonds with solutes and reside in channels between layers. This well explains why acetone solvent is easy to escape from the crystal structure during desolvation.展开更多
Detailed investigations on the microstructure and the mechanical properties of the wing membrane of the dragonfly are carried out. It is found that in the direction of the thickness the membrane was divided into three...Detailed investigations on the microstructure and the mechanical properties of the wing membrane of the dragonfly are carried out. It is found that in the direction of the thickness the membrane was divided into three layers rather than a single entity as traditionally considered, and on the surfaces the membrane displays a random distribution rough microstructure that is composed of numerous nanometer scale columns coated by the cuticle wax secreted. The characteristics of the surface structure are measured and described. The mechanical properties of the membranes taken separately from the wings of live and dead dragonflies are investigated by the nanoindentation technique. The Young＇s moduli obtained here are approximately two times greater than the previous result, and the reasons that yield the difference are discussed.展开更多
A one-dimensional chain coordination polymer [Cu（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized by reacting 2,4,6-trimethyl-benzoic acid, 1,10-phenanthroline and Cu（Ⅱ） perchlorate and its structure was charac...A one-dimensional chain coordination polymer [Cu（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized by reacting 2,4,6-trimethyl-benzoic acid, 1,10-phenanthroline and Cu（Ⅱ） perchlorate and its structure was characterized. Crystal data for this complex： tetragonal, space group I41, a = 2.0293（3）, b = 2.0293（3）, c = 1.3758（2） nm, α =β= γ = 90°, V= 5.6657（13） nm3, Dc= 1.379 g/cm3, Z = 8, μ（MoKa） = 0.815 mm-1, Mr = 588.14, F（000） = 2456, S = 1.047, R = 0.0459 and wR = 0.1053. The crystal structure shows that two neighboring Cu（Ⅱ） ions are linked together by one bridging-chelating 2,4,6-trimethyl-benzoic group, forming a one-dimensional chain structure. Each Cu（Ⅱ） ion is coordinated with two nitrogen atoms from one 1,10-phenanthroline molecule, three oxygen atoms from three 2,4,6-trimethyl-benzoic acid molecules and one oxygen atom from one water molecule, giving a six-coordinate distorted octahedral coordination geometry. The cyclic voltammetry behavior of the complex was also investigated.展开更多
A new copper complex 2{Cu（C10H8N2）[C8H11O2（COO）]（H2O）3}·（H2O）5 with bicycle[2.2.1]hept-2-en-5,6-dicarboxylic acid（H2L） [C7H8（COOH）2], basic copper carbonate and 2,2＇-bipyridine has been synthesized i...A new copper complex 2{Cu（C10H8N2）[C8H11O2（COO）]（H2O）3}·（H2O）5 with bicycle[2.2.1]hept-2-en-5,6-dicarboxylic acid（H2L） [C7H8（COOH）2], basic copper carbonate and 2,2＇-bipyridine has been synthesized in the mixed solvents of methanol and water. It crystallizes in the triclinic system, space group P1, with a = 7.4626（5）, b = 11.9779（8）, c = 12.9841（8）A, α = 109.7040（10）, β = 98.7550（10）, γ = 90.6240（10）°, V = 1077.50（12）A3, Dc = 1.538 g/cm^3, Z = 1, F（000） = 520, GOOF = 1.065, R = 0.0360 and wR = 0.0950. The copper ion is coordinated with four oxygen atoms from one H2 L molecule and three water molecules together with two nitrogen atoms from the 2,2＇-bipyridine molecule, forming a distorted octahedral coordination geometry. The thermal stability and electrochemical properties were also studied.展开更多
A novel one-dimensional chain coordination polymer [Mn（NAAh（4,4′-bipy）（H2O）4], has been synthesized with a-naphthaleneacetic acid, 4,4′-bipy and manganese（Ⅱ） sulfate as raw materials. Crystal data for this c...A novel one-dimensional chain coordination polymer [Mn（NAAh（4,4′-bipy）（H2O）4], has been synthesized with a-naphthaleneacetic acid, 4,4′-bipy and manganese（Ⅱ） sulfate as raw materials. Crystal data for this complex： monoclinic, space group P21/c, a = 1.1421（2）, b = 1.6337（3）, c = 0.94177（19） nm, β = 112.15（3）°, V = 1.6275（6） nm^3, De = 1.407 g/cm^3, Z = 2, μ（MoKa） = 0.467 mm^-1, F（000） = 722, S = 1.007, R= 0.0412 and wR = 0.1022. The crystal structure shows that two neighboring manganese（Ⅱ） ions are linked together by one 4,4′-bipy molecule, and the whole complex molecule forms a one-dimensional chain structure. Each manganese（Ⅱ） ion is coordinated with two oxygen atoms of two a-naphthaleneacetic acid molecules, two nitrogen atoms of two 4,4′-bipy molecules and two oxygen atoms from two water molecules, giving a distorted octahedral coordination geometry. The electrochemical properties were also analyzed.展开更多
Utilizing mononuclear complex Ni（2-mpac）2（H2O）2 as the molecular building block,a novel coordination polymer [Ni2（2-mpac）4（4,4＇-bpy）·2H2O]n（1,2-mpac = 5-methyl-2-pyrazinecar-boxylic acid,4,4＇-bpy = 4,4...Utilizing mononuclear complex Ni（2-mpac）2（H2O）2 as the molecular building block,a novel coordination polymer [Ni2（2-mpac）4（4,4＇-bpy）·2H2O]n（1,2-mpac = 5-methyl-2-pyrazinecar-boxylic acid,4,4＇-bpy = 4,4＇-bipyridine） was successfully synthesized and structurally characterized by X-ray single-crystal diffraction method.Crystal data：monoclinic,space group C2/c,a = 23.870（1）,b = 9.887（4）,c = 18.929（9） ,β = 126.840（5）°,V = 3575（3） 3,Z = 4,S = 1.046,μ = 1.594 mm-1,F（000） = 1768 and Dc = 1.127 g·cm-3.The final R = 0.0351 and wR = 0.0792 for 2372 observed reflections with Ⅰ 〉 2σ（Ⅰ） and R = 0.0564 and wR = 0.0938 for all reflections.展开更多
A new cadmium complex [Cd（phen）3]·（ClO4）2·（α-FRA）-（H2O）3 was prepared by self-assembly of α-furoic acid, 1,10-phenanthroline （phen）, and cadmium perchlorate. It crystallizes in the monoclinic sys...A new cadmium complex [Cd（phen）3]·（ClO4）2·（α-FRA）-（H2O）3 was prepared by self-assembly of α-furoic acid, 1,10-phenanthroline （phen）, and cadmium perchlorate. It crystallizes in the monoclinic system, space group P21/n, with a = 1.28130（15）, b = 2.5957（3）, c = 1.35449（16） nm, β = 109.395（2）°, V = 4.2492（9） nm^3, Dc = 1.491 g/cm^3, Z = 4, F（000） = 1926, GOOF = 1.023, the final R = 0.0729 and wR = 0.2086. The crystal structure analysis indicates that the cadmium ion is coordinated with six nitrogen atoms from six 1,10-phenanthroline molecules, giving a distorted octahedral coordination geometry. The cyclic voltametric behavior of the complex was also investigated.展开更多
One new cadmium complex [Cd（phen）3]·（ClO4）2·（p-MBA）2·（H2O）2 has been hydrothermally synthesized by reacting p-methylbenzoic acid （p-MBA）, 1,10-phenanthroline （phen） and cadmium perchlorate. ...One new cadmium complex [Cd（phen）3]·（ClO4）2·（p-MBA）2·（H2O）2 has been hydrothermally synthesized by reacting p-methylbenzoic acid （p-MBA）, 1,10-phenanthroline （phen） and cadmium perchlorate. It crystallizes in the triclinic system, space group P1, with a = 1.2809（3）, b = 1.3431（3）, c = 1.3734（3） nm, α = 84.259（4）, β = 71.603（3）, γ = 74.424（3）°, V= 2.1594（8） nm3, Do = 1.532 g/cm3, Z = 2, F（000） = 1008, μ= 0.697 mm^-1, R = 0.0646 and wR = 0.1648. The crystal structure shows that the cadmium ion is coordinated with six nitrogen atoms from three 1,10-phenanthroline molecules, forming a distorted octahedral coordination geometry. The result of electrochemical property analysis shows that the electron transfer in the electrode reaction is irreversible.展开更多
The hot or cold processing would induce the change and the inhomogeneous of the material mechanical properties in the local processing region of the structure,and it is difficult to obtain the specific mechanical prop...The hot or cold processing would induce the change and the inhomogeneous of the material mechanical properties in the local processing region of the structure,and it is difficult to obtain the specific mechanical properties in these regions by using the traditional material tensile test.To accurately get actual material mechanical properties in the local region of structure,a micro-indentation test system incorporated by an electronic universal material test device has been established.An indenter displacement sensor and a group of special micro-indenter assemblies are estab-lished.A numerical indentation inversion analysis method by using ABAQUS software is also proposed in this study.Based on the above test system and analysis platform,an approach to obtaining material mechanical properties in the local region of structures is proposed and established.The ball indentation test is performed and combined with the energy method by using various changed mechanical properties of 316L austenitic stainless steel under differ-ent elongations.The investigated results indicate that the material mechanical properties and the micro-indentation morphological changes have evidently relevance.Compared with the tensile test results,the deviations of material mechanical parameters,such as hardness H,the hardening exponent n,the yield strength σy and others are within 5%obtained through the indentation test and the finite element analysis.It provides an effective and convenient method for obtaining the actual material mechanical properties in the local processing region of the structure.展开更多
A novel C3-symmetrical molecule, 1,3,5-tri(9-ethyl-6-nitrocarbazol-3-yl) benzene(IV), was synthesized and characterized by 1 H NMR, 13 C NMR and UV-vis spectroscopy, elemental analyses and X-ray single crystal diffrac...A novel C3-symmetrical molecule, 1,3,5-tri(9-ethyl-6-nitrocarbazol-3-yl) benzene(IV), was synthesized and characterized by 1 H NMR, 13 C NMR and UV-vis spectroscopy, elemental analyses and X-ray single crystal diffraction analysis. For this complex: C48 H36 N6 O6, Mr = 792.83, triclinic system, space group P1, a = 11.568(6), b = 13.158(7), c = 17.856(10) ?, α = 95.419(9), β = 107.345(8), γ = 114.682(8)o, V = 2281(2) ?3, Z = 2, Dc = 1.154 g/cm3, λ = 0.71073 ?, F(000) = 828, S = 1.083, R = 0.0836 and wR = 0.1926 for 3304 observed reflections with I > 2ζ(I). The compound possesses good thermal stability with the decomposition temperature(Td) of 265 ℃. The absorption and emission spectra show that the compound can emit blue light in CHCl3, and the quantum yield of compound IV in EtOH was 0.66. Furthermore, the electrochemical properties of compound IV were also studied by cyclic voltammetry(CV) method, and the results correspond to the data of theoretical calculation by the Gaussian 09 software.展开更多
Two coordination compounds with a flexible ligand N,N？-diacetic acid imidazolium（HDAM）,{[Co（trans-DAM）（bipy）（H2O）2]（OH）·4H2O}n 1 and {[Cd（trans-DAM）（bipy）（H2O）]（NO3）？2H2O}n 2（bipy = 4,4＇-bip...Two coordination compounds with a flexible ligand N,N？-diacetic acid imidazolium（HDAM）,{[Co（trans-DAM）（bipy）（H2O）2]（OH）·4H2O}n 1 and {[Cd（trans-DAM）（bipy）（H2O）]（NO3）？2H2O}n 2（bipy = 4,4＇-bipyridine）,were prepared and characterized by single-crystal X-ray diffraction.Compound 1 crystallizes in monoclinic,space group P2/n with a = 7.589（6）,b = 11.444（2）,c = 12.894（3）（A°）,β = 90.99（3）°,V = 1119.8（4）（A°）^3,Z = 4,C8.5H14N2O5.5Co0.5,Mr = 261.68,Dc = 1.552 g/cm^3,F（000） = 546,μ = 0.832 mm^-1,the final R = 0.0657 and wR = 0.1958.Compound 2 crystallizes in the monoclinic C2 space group with a = 17.479（4）,b = 11.689（2）,c = 11.670（2）,β = 117.13（3）°,V = 2121.9（7）3,Z = 4,C17H21N5O10Cd,Mr = 567.79,Dc = 1.777 g/cm^3,F（000） = 1144,μ = 1.096 mm^-1,the final R = 0.0233 and wR = 0.0638.In 1,the Co（II） ions are linked by μ2-trans-DAM-and bipy ligands to build a 2D（4,4） rectangular grid layer,exhibiting a 4-connected sql net.As for 2,μ3-trans-DAM-and bipy bridge Cd（II） ions form a 2D double-layer,consisting of a couple of（4,4） grid layers,which can be viewed as a（3,4）-connected network.In both compounds,the 2D structures are stabilized by hydrogen bonding interactions to give 3D supramolecular frameworks.Additionally,FT-IR spectroscopy,UV-Visible spectroscopy,and the fluorescent properties are discussed.展开更多
We have investigated the doping behavior of rare earth element holmium （Ho3＋） in ZnO semiconductor. The structural, microstructure, and magnetic properties of Zn1-xHoxO （x=0.0, 0.04, and 0.05） thin films deposite...We have investigated the doping behavior of rare earth element holmium （Ho3＋） in ZnO semiconductor. The structural, microstructure, and magnetic properties of Zn1-xHoxO （x=0.0, 0.04, and 0.05） thin films deposited on Si（100） substrate by thermal evaporation technique were studied. The ceramic targets were prepared by conventional solid state ceramic technique. The pallets used as target were final sintered at 900℃ in the presence of N2 atmosphere. The experimental results of X-ray diffraction （XRD） spectra, surface morphology, and magnetic properties show that the Ho3＋ doped ZnO thin films has a strong influence on the materials properties. The higher angle shift in peak position and most preferred （101） orientation were observed in XRD pattern. These spectra confirmed the substitution of Ho3＋ in ZnO lattice. The surface morphology and stoichiometry for both bulk and thin films were analyzed by scanning electron microscopy and energy dispersive spectroscopy. It was observed that grain size decreases with the increase of Ho3＋. Room temperature ferromagnetism was observed for Zn0.95Ho0.050 films. The ferromagnetism might be attributed to the substitution of Ho ions for Zn2＋ in ZnO lattices.展开更多
Bimetallic clusters have aroused tremendous interest because the property changes like structure,size,and composition have occurred.Herein,a structural search of the global minimum for anionic LiMg_(n)^(-)(n=2-11) clu...Bimetallic clusters have aroused tremendous interest because the property changes like structure,size,and composition have occurred.Herein,a structural search of the global minimum for anionic LiMg_(n)^(-)(n=2-11) clusters is performed using an efficient crystal structure analysis by particle swarm optimization(CALYPSO) structural searching program with subsequent density functional theory(DFT) calculations.A great variety of low energetic isomers are converged,and the most stable ones are confirmed by comparing their total energy of each size.It is found that the LiMg_(n)^(-)clusters are structurally consistent with corresponding Mg clusters anions except for LiMg_(5)^(-)and LiMg_(7)^(-).In all the doped clusters,the Li atom prefers to occupy the convex position.Simulated photoelectron spectra(PES),Infrared(IR),and Raman spectra of LiMg_(n)^(-)could be used as an essential evidence for identifying cluster structures experimentally in the future.Stability study reveals that a tower-like structure of LiMg_(9)^(-)has prominent stability and can be identified as a magic number cluster.The reason might be that there are both closed-shell 1S^(2)1P^(6)1D^(10)2S^(2) electronic configurations and stronger Li-Mg bonds caused by sp hybridization in the LiMg_(9)^(-)cluster.展开更多
The structural, dielectric, lattice dynamical and thermodynamic properties of zinc-blende CdX （X=S, Se, Te） are studied by using a plane-wave pseudopotential method within the density-functional theory. Our calculat...The structural, dielectric, lattice dynamical and thermodynamic properties of zinc-blende CdX （X=S, Se, Te） are studied by using a plane-wave pseudopotential method within the density-functional theory. Our calculated lattice constants and bulk modulus are compared with the pubfished experimental and theoretical data. In addition, the Born effective charges, electronic dielectric tensors, phonon frequencies, and longitudinal opticaltransverse optical splitting are calculated by the linear-response approach. Some of the characteristics of the phonon-dispersion curves for zinc-blende CdX （X= S, Se, Te） are summarized. What is more, based on the lattice dynamical properties, we investigate the thermodynamic properties of CdX （X= S, Se, Te） and analyze the temperature dependences of the Helmholtz free energy F, the internal energy E, the entropy S and the constant-volume specific heat Cv. The results show that the heat capacities for CdTe, CdSe, and CdS approach approximately to the Petit-Dulong limit 6R.展开更多
This paper summed up experimental data for the structural analyses and properties of collagen sponge to be used as wound dressing or scaffolds of cell growth in tissue engineering. The structural analyses included UV ...This paper summed up experimental data for the structural analyses and properties of collagen sponge to be used as wound dressing or scaffolds of cell growth in tissue engineering. The structural analyses included UV spectrum, amino acid and electrophoresis, while the physicochemical properties were bulk density, water-binding capacity, digestibility and residue on ignition. The structural analysis showed that the collagen sponge made from bovine tendon was purely composed of type Ⅰ collagen, and contained many aggregated compositions with high molecular mass owing to the storage under ambient condition. The bulk density of the collagen sponge was between 18 and 21 mg/cm 3, water-binding capacity from 44 to 53 mg/mg, digestive time about half an hour and residue on ignition between 0.42% and 0.45%.展开更多
文摘Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.
基金financial support by the National Natural Science Foundation of China(No.12272094)the Key Project of National Defence Innovation Zone of Science and Technology Commission of CMC,China(No.XXX-033-01)the Natural Science Foundation of Fujian Province of China(No.2022J01541)。
文摘As a new addition to lightweight composite structures,the sandwich cylindrical shell with a metallic wire mesh core has emerged as a promising solution for thermodynamic performance analysis at elevated temperatures.The intricate interwoven cellular formations within the metallic wire mesh pose difficulties for thermo-mechanical modeling and property evaluation.First,the constitutive models employed to characterize hysteresis phenomena were presented,comprising isotropic elasticity,Bergstrom-Boyce model,Ogden hyper-elasticity,and parameter identification through mechanical examinations at varying temperatures.Second,the finite element modeling of cylindrical shell structures was determined for modal and steady-state dynamic analyses.Third,the experimental procedures were carried out,including the preparation of the sandwich cylindrical shell and the dynamic testing platform.The first-order natural frequency of the cylindrical shell structure is close to the resonance frequency of the dynamic test results,with a maximum error of 6.5%,demonstrating the accuracy of the simulation model.When compared to the solid-core cylindrical shell,the average insertion loss of the sandwich cylindrical shell structure within the frequency range of 10–1000 Hz at room temperature is up to 11.09 dB.Furthermore,at elevated temperatures,the average insertion loss of the sandwich cylindrical shell decreases but fluctuates as the temperature changes.
基金supported by the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(Grant No.CX2021006)the National Natural Science Foundation of China(Grant Nos.91860203,51727804,and 52130205)the Fundamental Research Funds for the Central Universities(Grant No.3102019TS0409).
文摘Herein,nanosized Hf_(6)Ta_(2)O_(17) encapsulated graphite flakes were firstly constructed using the sol-gel method,then deposited on the surface of carbon/carbon(C/C)composites by plasma spraying technique to prolong their service span in critical environments.Nanoindentation results affirmed the active influ-ence of graphite flakes on elevating the toughness of the Hf_(6)Ta_(2)O_(17) coating.Besides,after being exposed to the oxyacetylene torch with a peak temperature of about 2000℃,the sample achieved near zero ab-lation(0.06 mg/s),meanwhile its porosity and mass ablation rate showed 39.5%and 60.0%reduction when compared to pure Hf_(6)Ta_(2)O_(17) sample.During exposure,the external Hf_(6)Ta_(2)O_(17) served as an oxy-gen barrier for internal graphite flakes,inversely internal graphite flakes provided a“pinning”effect on external Hf_(6)Ta_(2)O_(17),which accounted for its exceptional ablation performance.This work offers a new insight into the design of surface modification of C/C composites and other high-temperature structural materials.
文摘Precast concrete structures have gained popularity due to their advantages.However,the seismic performance of their connection joints remains an area of ongoing research and improvement.Grouted Sleeve Connection(GSC)offers a solution for connecting reinforcements in precast components,but their vulnerability to internal defects,such as construction errors and material variability,can significantly impact performance.This article presents a finite element analysis(FEA)to evaluate the impact of internal grouting defects in GSC on the structural performance of precast reinforced concrete columns.Four finite elementmodels representing GSC with varying degrees of defects were used to investigate the effects on mechanical properties,including bearing capacity,stress-deformation behavior,and stiffness degradation.The study highlights the significant impact of internal grouting defects on the mechanical performance of GSC,with findings indicating a decrease in stiffness,increased plastic deformation,and reduced energy dissipation as the proportion of internal defects rises.The analysis reveals that the internal defects in GSC act as stress concentration points,leading to early crack formation and accelerated damage under cyclic loading.By improving construction quality and reducing the prevalence of grouting defects,the adverse effects on the performance of GSC can be mitigated.Compared to defect-free specimens,those with defects of 30%exhibited a 31.23%reduction in horizontal bearing capacity,highlighting the importance of minimizing defects in practical engineering applications.
文摘Erythromycin thiocyanate is widely used for the production of other macrolide antibiotics. In this work, a novel heterosolvate of this pharmaceutical compound has been obtained and characterized for the first time, which was transformed from the dihydrate form in the acetone solvent through evaporation crystallization. Thermal behavior together with compositional analysis revealed that both water and acetone molecules participated in the formation of the crystal lattice which is rarely reported before. The general chemical name of the heterosolvate may be defined as erythromycin thiocyanate sesquihydrate hemiacetonate. Furthermore, studies on solid-state spectral analysis provided strong evidence of intermolecular hydrogen bonds in heterosolvate crystals. According to the crystal structure determined by single crystal X-ray diffraction, the formation mechanism of the heterosolvate is proposed in which strong multihydrogen bondings between water and solute molecules form the layer structure. While acetone molecules form single-hydrogen bonds with solutes and reside in channels between layers. This well explains why acetone solvent is easy to escape from the crystal structure during desolvation.
基金The project supported by the National Natural Science Foundation of China(10372102 and 10672164)
文摘Detailed investigations on the microstructure and the mechanical properties of the wing membrane of the dragonfly are carried out. It is found that in the direction of the thickness the membrane was divided into three layers rather than a single entity as traditionally considered, and on the surfaces the membrane displays a random distribution rough microstructure that is composed of numerous nanometer scale columns coated by the cuticle wax secreted. The characteristics of the surface structure are measured and described. The mechanical properties of the membranes taken separately from the wings of live and dead dragonflies are investigated by the nanoindentation technique. The Young＇s moduli obtained here are approximately two times greater than the previous result, and the reasons that yield the difference are discussed.
基金supported by the Foundation of Education Committee of Hunan Province(06C195)the Research Award Fund for Outstanding Young Teachers of Hengyang Normal University(2006)Supported by the construct program of the key discipline in hunan province.
文摘A one-dimensional chain coordination polymer [Cu（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized by reacting 2,4,6-trimethyl-benzoic acid, 1,10-phenanthroline and Cu（Ⅱ） perchlorate and its structure was characterized. Crystal data for this complex： tetragonal, space group I41, a = 2.0293（3）, b = 2.0293（3）, c = 1.3758（2） nm, α =β= γ = 90°, V= 5.6657（13） nm3, Dc= 1.379 g/cm3, Z = 8, μ（MoKa） = 0.815 mm-1, Mr = 588.14, F（000） = 2456, S = 1.047, R = 0.0459 and wR = 0.1053. The crystal structure shows that two neighboring Cu（Ⅱ） ions are linked together by one bridging-chelating 2,4,6-trimethyl-benzoic group, forming a one-dimensional chain structure. Each Cu（Ⅱ） ion is coordinated with two nitrogen atoms from one 1,10-phenanthroline molecule, three oxygen atoms from three 2,4,6-trimethyl-benzoic acid molecules and one oxygen atom from one water molecule, giving a six-coordinate distorted octahedral coordination geometry. The cyclic voltammetry behavior of the complex was also investigated.
基金Supported by the Natural Science Foundation of Hunan Province(No.11JJ9006)Key Project of Science and Technology Plan of Hunan Province(2012FJ2002)the Construct Program of the Key Discipline in Hunan Province
文摘A new copper complex 2{Cu（C10H8N2）[C8H11O2（COO）]（H2O）3}·（H2O）5 with bicycle[2.2.1]hept-2-en-5,6-dicarboxylic acid（H2L） [C7H8（COOH）2], basic copper carbonate and 2,2＇-bipyridine has been synthesized in the mixed solvents of methanol and water. It crystallizes in the triclinic system, space group P1, with a = 7.4626（5）, b = 11.9779（8）, c = 12.9841（8）A, α = 109.7040（10）, β = 98.7550（10）, γ = 90.6240（10）°, V = 1077.50（12）A3, Dc = 1.538 g/cm^3, Z = 1, F（000） = 520, GOOF = 1.065, R = 0.0360 and wR = 0.0950. The copper ion is coordinated with four oxygen atoms from one H2 L molecule and three water molecules together with two nitrogen atoms from the 2,2＇-bipyridine molecule, forming a distorted octahedral coordination geometry. The thermal stability and electrochemical properties were also studied.
基金Supported by the Foundation of Education Committee of Hunan Province (06C195)Fund for Construction of Key Subject in the Eleventh Five-year Plan of Higher Learning of Education in Hunan Province
文摘A novel one-dimensional chain coordination polymer [Mn（NAAh（4,4′-bipy）（H2O）4], has been synthesized with a-naphthaleneacetic acid, 4,4′-bipy and manganese（Ⅱ） sulfate as raw materials. Crystal data for this complex： monoclinic, space group P21/c, a = 1.1421（2）, b = 1.6337（3）, c = 0.94177（19） nm, β = 112.15（3）°, V = 1.6275（6） nm^3, De = 1.407 g/cm^3, Z = 2, μ（MoKa） = 0.467 mm^-1, F（000） = 722, S = 1.007, R= 0.0412 and wR = 0.1022. The crystal structure shows that two neighboring manganese（Ⅱ） ions are linked together by one 4,4′-bipy molecule, and the whole complex molecule forms a one-dimensional chain structure. Each manganese（Ⅱ） ion is coordinated with two oxygen atoms of two a-naphthaleneacetic acid molecules, two nitrogen atoms of two 4,4′-bipy molecules and two oxygen atoms from two water molecules, giving a distorted octahedral coordination geometry. The electrochemical properties were also analyzed.
基金Supported by the National Natural Science Foundation of China (20771089)Natural Science Foundation of Shaanxi Province (2009JQ2015,SJ08B09,2007B02)+1 种基金Special Research Fund of Education Department of Shaanxi Province (09JK798)Special Research Fund of Xianyang Normal University (08XSYK305,09XSYK215)
文摘Utilizing mononuclear complex Ni（2-mpac）2（H2O）2 as the molecular building block,a novel coordination polymer [Ni2（2-mpac）4（4,4＇-bpy）·2H2O]n（1,2-mpac = 5-methyl-2-pyrazinecar-boxylic acid,4,4＇-bpy = 4,4＇-bipyridine） was successfully synthesized and structurally characterized by X-ray single-crystal diffraction method.Crystal data：monoclinic,space group C2/c,a = 23.870（1）,b = 9.887（4）,c = 18.929（9） ,β = 126.840（5）°,V = 3575（3） 3,Z = 4,S = 1.046,μ = 1.594 mm-1,F（000） = 1768 and Dc = 1.127 g·cm-3.The final R = 0.0351 and wR = 0.0792 for 2372 observed reflections with Ⅰ 〉 2σ（Ⅰ） and R = 0.0564 and wR = 0.0938 for all reflections.
基金Supported by the construct program of the key discipline in hunan provincethe Research Award Fund for the Outstanding Young Teachers of Hengyang Normal University (2006)
文摘A new cadmium complex [Cd（phen）3]·（ClO4）2·（α-FRA）-（H2O）3 was prepared by self-assembly of α-furoic acid, 1,10-phenanthroline （phen）, and cadmium perchlorate. It crystallizes in the monoclinic system, space group P21/n, with a = 1.28130（15）, b = 2.5957（3）, c = 1.35449（16） nm, β = 109.395（2）°, V = 4.2492（9） nm^3, Dc = 1.491 g/cm^3, Z = 4, F（000） = 1926, GOOF = 1.023, the final R = 0.0729 and wR = 0.2086. The crystal structure analysis indicates that the cadmium ion is coordinated with six nitrogen atoms from six 1,10-phenanthroline molecules, giving a distorted octahedral coordination geometry. The cyclic voltametric behavior of the complex was also investigated.
基金the Foundation of Education Committee of Hunan Province (06C195)the Research Award Fund for Outstanding Young Teachers of Hengyang Normal University (2006)the construct program of the Key Discipline in Hunan Province
文摘One new cadmium complex [Cd（phen）3]·（ClO4）2·（p-MBA）2·（H2O）2 has been hydrothermally synthesized by reacting p-methylbenzoic acid （p-MBA）, 1,10-phenanthroline （phen） and cadmium perchlorate. It crystallizes in the triclinic system, space group P1, with a = 1.2809（3）, b = 1.3431（3）, c = 1.3734（3） nm, α = 84.259（4）, β = 71.603（3）, γ = 74.424（3）°, V= 2.1594（8） nm3, Do = 1.532 g/cm3, Z = 2, F（000） = 1008, μ= 0.697 mm^-1, R = 0.0646 and wR = 0.1648. The crystal structure shows that the cadmium ion is coordinated with six nitrogen atoms from three 1,10-phenanthroline molecules, forming a distorted octahedral coordination geometry. The result of electrochemical property analysis shows that the electron transfer in the electrode reaction is irreversible.
基金Supported by National Natural Science Foundation of China(Grant No.52075434)Key R&D Projects in Shaanxi Province(Grant No.2021KW-36).
文摘The hot or cold processing would induce the change and the inhomogeneous of the material mechanical properties in the local processing region of the structure,and it is difficult to obtain the specific mechanical properties in these regions by using the traditional material tensile test.To accurately get actual material mechanical properties in the local region of structure,a micro-indentation test system incorporated by an electronic universal material test device has been established.An indenter displacement sensor and a group of special micro-indenter assemblies are estab-lished.A numerical indentation inversion analysis method by using ABAQUS software is also proposed in this study.Based on the above test system and analysis platform,an approach to obtaining material mechanical properties in the local region of structures is proposed and established.The ball indentation test is performed and combined with the energy method by using various changed mechanical properties of 316L austenitic stainless steel under differ-ent elongations.The investigated results indicate that the material mechanical properties and the micro-indentation morphological changes have evidently relevance.Compared with the tensile test results,the deviations of material mechanical parameters,such as hardness H,the hardening exponent n,the yield strength σy and others are within 5%obtained through the indentation test and the finite element analysis.It provides an effective and convenient method for obtaining the actual material mechanical properties in the local processing region of the structure.
基金supported by the Fund for the Soft Science project of Shanxi Province(No.2016042008-1)the National Natural Science Foundation of China(No.21701121)the Natural Science Foundation of Shanxi Province(No.201601D102015 and 201801D121064)
文摘A novel C3-symmetrical molecule, 1,3,5-tri(9-ethyl-6-nitrocarbazol-3-yl) benzene(IV), was synthesized and characterized by 1 H NMR, 13 C NMR and UV-vis spectroscopy, elemental analyses and X-ray single crystal diffraction analysis. For this complex: C48 H36 N6 O6, Mr = 792.83, triclinic system, space group P1, a = 11.568(6), b = 13.158(7), c = 17.856(10) ?, α = 95.419(9), β = 107.345(8), γ = 114.682(8)o, V = 2281(2) ?3, Z = 2, Dc = 1.154 g/cm3, λ = 0.71073 ?, F(000) = 828, S = 1.083, R = 0.0836 and wR = 0.1926 for 3304 observed reflections with I > 2ζ(I). The compound possesses good thermal stability with the decomposition temperature(Td) of 265 ℃. The absorption and emission spectra show that the compound can emit blue light in CHCl3, and the quantum yield of compound IV in EtOH was 0.66. Furthermore, the electrochemical properties of compound IV were also studied by cyclic voltammetry(CV) method, and the results correspond to the data of theoretical calculation by the Gaussian 09 software.
基金supported by the National Natural Science Foundation of China (No. 20873021)
文摘Two coordination compounds with a flexible ligand N,N？-diacetic acid imidazolium（HDAM）,{[Co（trans-DAM）（bipy）（H2O）2]（OH）·4H2O}n 1 and {[Cd（trans-DAM）（bipy）（H2O）]（NO3）？2H2O}n 2（bipy = 4,4＇-bipyridine）,were prepared and characterized by single-crystal X-ray diffraction.Compound 1 crystallizes in monoclinic,space group P2/n with a = 7.589（6）,b = 11.444（2）,c = 12.894（3）（A°）,β = 90.99（3）°,V = 1119.8（4）（A°）^3,Z = 4,C8.5H14N2O5.5Co0.5,Mr = 261.68,Dc = 1.552 g/cm^3,F（000） = 546,μ = 0.832 mm^-1,the final R = 0.0657 and wR = 0.1958.Compound 2 crystallizes in the monoclinic C2 space group with a = 17.479（4）,b = 11.689（2）,c = 11.670（2）,β = 117.13（3）°,V = 2121.9（7）3,Z = 4,C17H21N5O10Cd,Mr = 567.79,Dc = 1.777 g/cm^3,F（000） = 1144,μ = 1.096 mm^-1,the final R = 0.0233 and wR = 0.0638.In 1,the Co（II） ions are linked by μ2-trans-DAM-and bipy ligands to build a 2D（4,4） rectangular grid layer,exhibiting a 4-connected sql net.As for 2,μ3-trans-DAM-and bipy bridge Cd（II） ions form a 2D double-layer,consisting of a couple of（4,4） grid layers,which can be viewed as a（3,4）-connected network.In both compounds,the 2D structures are stabilized by hydrogen bonding interactions to give 3D supramolecular frameworks.Additionally,FT-IR spectroscopy,UV-Visible spectroscopy,and the fluorescent properties are discussed.
文摘We have investigated the doping behavior of rare earth element holmium （Ho3＋） in ZnO semiconductor. The structural, microstructure, and magnetic properties of Zn1-xHoxO （x=0.0, 0.04, and 0.05） thin films deposited on Si（100） substrate by thermal evaporation technique were studied. The ceramic targets were prepared by conventional solid state ceramic technique. The pallets used as target were final sintered at 900℃ in the presence of N2 atmosphere. The experimental results of X-ray diffraction （XRD） spectra, surface morphology, and magnetic properties show that the Ho3＋ doped ZnO thin films has a strong influence on the materials properties. The higher angle shift in peak position and most preferred （101） orientation were observed in XRD pattern. These spectra confirmed the substitution of Ho3＋ in ZnO lattice. The surface morphology and stoichiometry for both bulk and thin films were analyzed by scanning electron microscopy and energy dispersive spectroscopy. It was observed that grain size decreases with the increase of Ho3＋. Room temperature ferromagnetism was observed for Zn0.95Ho0.050 films. The ferromagnetism might be attributed to the substitution of Ho ions for Zn2＋ in ZnO lattices.
基金Project supported by the National Natural Science Foundation of China(Grant No.11404008)the Innovation Training Program for College Students of Shanxi Province of China(Grant No.S201910721061)the Innovation Training Program for College Students of Baoji University of Arts and Sciences(Grant No.20191XJ087)。
文摘Bimetallic clusters have aroused tremendous interest because the property changes like structure,size,and composition have occurred.Herein,a structural search of the global minimum for anionic LiMg_(n)^(-)(n=2-11) clusters is performed using an efficient crystal structure analysis by particle swarm optimization(CALYPSO) structural searching program with subsequent density functional theory(DFT) calculations.A great variety of low energetic isomers are converged,and the most stable ones are confirmed by comparing their total energy of each size.It is found that the LiMg_(n)^(-)clusters are structurally consistent with corresponding Mg clusters anions except for LiMg_(5)^(-)and LiMg_(7)^(-).In all the doped clusters,the Li atom prefers to occupy the convex position.Simulated photoelectron spectra(PES),Infrared(IR),and Raman spectra of LiMg_(n)^(-)could be used as an essential evidence for identifying cluster structures experimentally in the future.Stability study reveals that a tower-like structure of LiMg_(9)^(-)has prominent stability and can be identified as a magic number cluster.The reason might be that there are both closed-shell 1S^(2)1P^(6)1D^(10)2S^(2) electronic configurations and stronger Li-Mg bonds caused by sp hybridization in the LiMg_(9)^(-)cluster.
基金Supported by the National Natural Science Foundation of China under Grant No 11374217
文摘The structural, dielectric, lattice dynamical and thermodynamic properties of zinc-blende CdX （X=S, Se, Te） are studied by using a plane-wave pseudopotential method within the density-functional theory. Our calculated lattice constants and bulk modulus are compared with the pubfished experimental and theoretical data. In addition, the Born effective charges, electronic dielectric tensors, phonon frequencies, and longitudinal opticaltransverse optical splitting are calculated by the linear-response approach. Some of the characteristics of the phonon-dispersion curves for zinc-blende CdX （X= S, Se, Te） are summarized. What is more, based on the lattice dynamical properties, we investigate the thermodynamic properties of CdX （X= S, Se, Te） and analyze the temperature dependences of the Helmholtz free energy F, the internal energy E, the entropy S and the constant-volume specific heat Cv. The results show that the heat capacities for CdTe, CdSe, and CdS approach approximately to the Petit-Dulong limit 6R.
文摘This paper summed up experimental data for the structural analyses and properties of collagen sponge to be used as wound dressing or scaffolds of cell growth in tissue engineering. The structural analyses included UV spectrum, amino acid and electrophoresis, while the physicochemical properties were bulk density, water-binding capacity, digestibility and residue on ignition. The structural analysis showed that the collagen sponge made from bovine tendon was purely composed of type Ⅰ collagen, and contained many aggregated compositions with high molecular mass owing to the storage under ambient condition. The bulk density of the collagen sponge was between 18 and 21 mg/cm 3, water-binding capacity from 44 to 53 mg/mg, digestive time about half an hour and residue on ignition between 0.42% and 0.45%.
