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
Design a precision electroplating mechanical structure for automobiles based on finite element analysis method and analyze its mechanical properties.Taking the automobile steering knuckle as the research object,ABAQUS...Design a precision electroplating mechanical structure for automobiles based on finite element analysis method and analyze its mechanical properties.Taking the automobile steering knuckle as the research object,ABAQUS parametric modeling technology is used to construct its three-dimensional geometric model,and geometric simplification is carried out.Two surface treatment processes,HK-35 zinc nickel alloy electroplating and pure zinc electroplating,were designed,and the influence of different coatings on the mechanical properties of steering knuckles was compared and analyzed through numerical simulation.At the same time,standard specimens were prepared for salt spray corrosion testing and scratch method combined strength testing to verify the numerical simulation results.The results showed that under emergency braking and composite working conditions,the peak Von Mises stress of the zinc nickel alloy coating was 119.85 MPa,which was lower than that of the pure zinc coating and the alkaline electroplated zinc layer.Its equivalent strain value was 652×10^(-6),which was lower than that of the pure zinc coating and the alkaline electroplated zinc layer.Experimental data confirms that zinc nickel alloy coatings exhibit significant advantages in stress distribution uniformity,strain performance,and load-bearing capacity in high stress zones.The salt spray corrosion test further indicates that the coating has superior corrosion resistance and coating substrate interface bonding strength,which can significantly improve the mechanical stability and long-term reliability of automotive precision electroplating mechanical structures.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
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
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
By extending the concept of diffusion to the potential energy landscapes(PELs), we introduce the meansquared energy difference(MSED) as a novel quantity to investigate the intrinsic properties of supercooled liquids. ...By extending the concept of diffusion to the potential energy landscapes(PELs), we introduce the meansquared energy difference(MSED) as a novel quantity to investigate the intrinsic properties of supercooled liquids. MSED can provide a clear description of the “energy relaxation” process on a PEL. Through MSED analysis, we have obtained a characteristic time similar to that derived from structure analysis, namely τ_(α)^(*).Further, we establish a connection between MSED and the feature of PELs, providing a concise and quantitative description of PELs. The relaxation behavior of energy has been found to follow a stretched exponential form.As the temperature decreases, the roughness of the accessible PEL changes significantly around a characteristic temperature T_(x), which is 20% higher than the glass transition temperature T_(g) and is comparable to the critical temperature of the mode-coupling theory. More importantly, one of the PEL parameters is closely related to the Adam–Gibbs configurational entropy. The present research, which directly links the PEL to the relaxation process, provides avenues for further research of glasses.展开更多
In this paper, the buoyancy, kinetic properties and stability of air floated structures have been studied by theoretical and experimental methods. The equations for calculation of the buoyancy of the air floated buoy ...In this paper, the buoyancy, kinetic properties and stability of air floated structures have been studied by theoretical and experimental methods. The equations for calculation of the buoyancy of the air floated buoy are derived according to the Boyler law and the equilibrium equations of the air floated structure are established. Through simplification of the air floated structure as a single freedom rigid body and spring system, the natural period of heaving and some kinetic properties are discussed. In the stability analysis, the formulas for calculation of the meta centric height are presented. The theoretical results are in good agreement with the data observed from the model test and prototype test. The air buoyancy decrease coefficient presented in this paper has a large influence on the floating state, stability and dynamic properties of the air floated structure. The stability of the air floated structure can also be judged by the parameter of meta centric height, and calculations show that the air floated structure is less stable than the conventional float.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
ObjectiveTo investigate the anticancer property of marine sediment actinomycetes against two different breast cancer cell lines.MethodsIn vitro anticancer activity was carried out against breast (MCF-7 and MDA-MB-231)...ObjectiveTo investigate the anticancer property of marine sediment actinomycetes against two different breast cancer cell lines.MethodsIn vitro anticancer activity was carried out against breast (MCF-7 and MDA-MB-231) cancer cell lines. Partial sequences of the 16s rRNA gene, phylogenetic tree construction, multiple sequence analysis and secondary structure analysis were also carried out with the actinomycetes isolates.ResultsOf the selected five actinomycete isolates, ACT01 and ACT02 showed the IC50 value with (10.13±0.92) and (22.34±5.82) μg/mL concentrations, respectively for MCF-7 cell line at 48 h, but ACT01 showed the minimum (18.54±2.49 μg/mL) level of IC50 value with MDA-MB-231 cell line. Further, the 16s rRNA partial sequences of ACT01, ACT02, ACT03, ACT04 and ACT05 isolates were also deposited in NCBI data bank with the accession numbers of GQ478246, GQ478247, GQ478248, GQ478249 and GQ478250, respectively. The phylogenetic tree analysis showed that, the isolates of ACT02 and ACT03 were represented in group I and III, respectively, but ACT01 and ACT02 were represented in group II. The multiple sequence alignment of the actinomycete isolates showed that, the maximum identical conserved regions were identified with the nucleotide regions of 125 to 221st base pairs, 65 to 119th base pairs and 55, 48 and 31st base pairs. Secondary structure prediction of the 16s rRNA showed that, the maximum free energy was consumed with ACT03 isolate (-45.4 kkal/mol) and the minimum free energy was consumed with ACT04 isolate (?7.6 kkal/mol).ConclusionsThe actinomycete isolates of ACT01 and ACT02 (GQ478246 and GQ478247) which are isolated from sediment sample can be further used as anticancer agents against breast cancer cell lines.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
In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical prope...In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.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
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.
文摘Design a precision electroplating mechanical structure for automobiles based on finite element analysis method and analyze its mechanical properties.Taking the automobile steering knuckle as the research object,ABAQUS parametric modeling technology is used to construct its three-dimensional geometric model,and geometric simplification is carried out.Two surface treatment processes,HK-35 zinc nickel alloy electroplating and pure zinc electroplating,were designed,and the influence of different coatings on the mechanical properties of steering knuckles was compared and analyzed through numerical simulation.At the same time,standard specimens were prepared for salt spray corrosion testing and scratch method combined strength testing to verify the numerical simulation results.The results showed that under emergency braking and composite working conditions,the peak Von Mises stress of the zinc nickel alloy coating was 119.85 MPa,which was lower than that of the pure zinc coating and the alkaline electroplated zinc layer.Its equivalent strain value was 652×10^(-6),which was lower than that of the pure zinc coating and the alkaline electroplated zinc layer.Experimental data confirms that zinc nickel alloy coatings exhibit significant advantages in stress distribution uniformity,strain performance,and load-bearing capacity in high stress zones.The salt spray corrosion test further indicates that the coating has superior corrosion resistance and coating substrate interface bonding strength,which can significantly improve the mechanical stability and long-term reliability of automotive precision electroplating mechanical structures.
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.
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.
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supported by the National Key Research and Development Program of China (Grant No. 2022YFA1404603)by the National Natural Science Foundation of China (Grant Nos. 12274127 and 12188101)。
文摘By extending the concept of diffusion to the potential energy landscapes(PELs), we introduce the meansquared energy difference(MSED) as a novel quantity to investigate the intrinsic properties of supercooled liquids. MSED can provide a clear description of the “energy relaxation” process on a PEL. Through MSED analysis, we have obtained a characteristic time similar to that derived from structure analysis, namely τ_(α)^(*).Further, we establish a connection between MSED and the feature of PELs, providing a concise and quantitative description of PELs. The relaxation behavior of energy has been found to follow a stretched exponential form.As the temperature decreases, the roughness of the accessible PEL changes significantly around a characteristic temperature T_(x), which is 20% higher than the glass transition temperature T_(g) and is comparable to the critical temperature of the mode-coupling theory. More importantly, one of the PEL parameters is closely related to the Adam–Gibbs configurational entropy. The present research, which directly links the PEL to the relaxation process, provides avenues for further research of glasses.
文摘In this paper, the buoyancy, kinetic properties and stability of air floated structures have been studied by theoretical and experimental methods. The equations for calculation of the buoyancy of the air floated buoy are derived according to the Boyler law and the equilibrium equations of the air floated structure are established. Through simplification of the air floated structure as a single freedom rigid body and spring system, the natural period of heaving and some kinetic properties are discussed. In the stability analysis, the formulas for calculation of the meta centric height are presented. The theoretical results are in good agreement with the data observed from the model test and prototype test. The air buoyancy decrease coefficient presented in this paper has a large influence on the floating state, stability and dynamic properties of the air floated structure. The stability of the air floated structure can also be judged by the parameter of meta centric height, and calculations show that the air floated structure is less stable than the conventional float.
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 National Natural Science Foundation of China(61233004,61221003,61374109,61104091,61304078,61473184)National Basic Research Program of China(973 Program)(2013CB035500)+2 种基金the International Cooperation Program of Shanghai Science and Technology Commission(12230709600)the Higher Education Research Fund for the Doctoral Program of China(20120073130006,20110073110018)the China Postdoctoral Science Foundation(2013M540364)
基金supported by Indian Council of Medical Research,New Delhi(grant No.59/6/200/BMS/TRM)
文摘ObjectiveTo investigate the anticancer property of marine sediment actinomycetes against two different breast cancer cell lines.MethodsIn vitro anticancer activity was carried out against breast (MCF-7 and MDA-MB-231) cancer cell lines. Partial sequences of the 16s rRNA gene, phylogenetic tree construction, multiple sequence analysis and secondary structure analysis were also carried out with the actinomycetes isolates.ResultsOf the selected five actinomycete isolates, ACT01 and ACT02 showed the IC50 value with (10.13±0.92) and (22.34±5.82) μg/mL concentrations, respectively for MCF-7 cell line at 48 h, but ACT01 showed the minimum (18.54±2.49 μg/mL) level of IC50 value with MDA-MB-231 cell line. Further, the 16s rRNA partial sequences of ACT01, ACT02, ACT03, ACT04 and ACT05 isolates were also deposited in NCBI data bank with the accession numbers of GQ478246, GQ478247, GQ478248, GQ478249 and GQ478250, respectively. The phylogenetic tree analysis showed that, the isolates of ACT02 and ACT03 were represented in group I and III, respectively, but ACT01 and ACT02 were represented in group II. The multiple sequence alignment of the actinomycete isolates showed that, the maximum identical conserved regions were identified with the nucleotide regions of 125 to 221st base pairs, 65 to 119th base pairs and 55, 48 and 31st base pairs. Secondary structure prediction of the 16s rRNA showed that, the maximum free energy was consumed with ACT03 isolate (-45.4 kkal/mol) and the minimum free energy was consumed with ACT04 isolate (?7.6 kkal/mol).ConclusionsThe actinomycete isolates of ACT01 and ACT02 (GQ478246 and GQ478247) which are isolated from sediment sample can be further used as anticancer agents against breast cancer cell lines.
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financially supported by the National Natural Science Foundation of China(No.52174291)。
文摘In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.
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.
