Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7...Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7Cr1C4,Mo7W1C4,Mo6W2C4,and Mo6W1Cr1C4 are stable and the stability follows the sequence：Mo6W1Cr1C4〉Mo7W1C4〉Mo7Cr1C4〉 Mo6W2C4〉 Mo8C4.Mo6W1Cr1C4 shows the highest stability,deformation resistance and hardness.G/B（shear modulus/bulk modulus）and Poisson′s ratio of the stable hexa-（Mo,Cr,W）2C are all larger than 1.75 and 0.26,respectively,which indicates that they are all brittle.The anisotropies are mainly due to the different Vogit shear modulus/Reuss shear modulus;the mechanical anisotropy of Mo7Cr1C4 is the largest,and that of Mo8C4 is the smallest.Moreover,the obtained Debye temperatureΘDand heat capacity Cpindicate that Mo6W2C4 possesses the best thermal conductivity（ΘD=497.72K）,while Mo7Cr1C4 and Mo6W2C4possess the largest heat capacity when the temperature is in the range of 0-10 Kand larger than 10 K,respectively.From the electronic property analysis,the doped Cr and W atoms can not only participate in orbitals hybridization themselves but also enhance the orbitals hybridization between Mo and C atoms,which can reinforce the interatomic interactions.展开更多
Single-phase SrM ultrafine powders with single-domain particle ranging from 200 to 400 nm in size were successfully synthesized by a cetyltrimethylammonium bromide（CTAB）-as sis ted co-precipitation method,and excell...Single-phase SrM ultrafine powders with single-domain particle ranging from 200 to 400 nm in size were successfully synthesized by a cetyltrimethylammonium bromide（CTAB）-as sis ted co-precipitation method,and excellent magnetic properties with saturation magnetization of 68.6 A·m^2·kg^（-1） and coercive field of 0.5250 T are obtained.As CTAB content exceeds 5.0 wt%,the impurities emerge due to the deterioration of simultaneous precipitations of the starting materials and the deviation of Sr/Fe molar ratio from stoichiometry ratio in the local microdomains by employing CTAB in co-precipitation process.Also,the use of CTAB can effectively improve the homogeneities of Fe-precursor particles with Sr-precursor particles,exert surface barriers to inhibit interdiffusion,and constrain the crystal growth in the local microdomains during sintering,resulting in smaller particle sizes and more uniform particle size distribution.展开更多
The relationship between the graft yield and the effect of hexafiuorobutyl methacrylate graft treatment on the structural changes of the silk fibers was studied on the basis of the results of scanning electron microgr...The relationship between the graft yield and the effect of hexafiuorobutyl methacrylate graft treatment on the structural changes of the silk fibers was studied on the basis of the results of scanning electron micrograph photographs （SEM）, infrared spectroscopy （IR）, Raman spectrum, wide-angle X-ray diffraction patterns （WAXD）, nuclear magnetic resonance（NMR） and amion acid analysis. The results showed that the crystalline regions of grafted fibers were hardly affected and the fiber fission occurred on the cross sections of grafted fibers. The surface of fibers was covered with a high polymer film. The Raman spectrum showed there was little change in the conformation of grafted fibers which mainly remained β-sheet conformation. The IR of the grafted silk fibers showed new absorption of bands occurred which belonged to the stretching-vibrationabsorption-peak bands of Vo-o and VC-F of aliphatic ester species. The CF3-, -CF2- and -CFH- grafted silk macromodecul were verified in the NMR spectrum. The amion acid analysis indicated fluoride monomers were inclined to graft with TYR, ARG and CLU silk fibers.展开更多
Hydrothermal reaction of MgCl2 and ethyl tetrazolate-5-carboxylate at 160 ℃unexpectedly yielded compound {（H3O）[Mg（H2O）6]Cl3} （1）. The result of X-ray diffraction analysis indicates that 1 crystallizes in the m...Hydrothermal reaction of MgCl2 and ethyl tetrazolate-5-carboxylate at 160 ℃unexpectedly yielded compound {（H3O）[Mg（H2O）6]Cl3} （1）. The result of X-ray diffraction analysis indicates that 1 crystallizes in the monoclinic system, space group C2/c with a = 9.2896（3）, b = 9.5570（4）, c = 13.3169（5） A, β = 90.1221（12）°, V= 1182.28（8） A3, Z = 4, Mr = 257.78, Dc = 1.448 g/cm3, μ = 0.824 mm^-1, F（000） = 536, R = 0.0265 and wR - 0.0706. 1 is composed of one hexa-aqua-magnesium（Ⅱ） ion, one hydroxonium ion, and three chlorine anions. These three components weave a perfect three-dimensional （3D） （4,4,6,12）-connected hydrogen bonding network within 1.展开更多
A rapid and facile synthesis of N-substituted 2,3,3a,4,7,7a-hexahydroisoindole-l,3-dione derivatives via microwave-promoted Beller three-component domino reaction of α,β,-unsaturated aldehydes, amides and N-substitu...A rapid and facile synthesis of N-substituted 2,3,3a,4,7,7a-hexahydroisoindole-l,3-dione derivatives via microwave-promoted Beller three-component domino reaction of α,β,-unsaturated aldehydes, amides and N-substituted maleimides was described.展开更多
文摘Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7Cr1C4,Mo7W1C4,Mo6W2C4,and Mo6W1Cr1C4 are stable and the stability follows the sequence：Mo6W1Cr1C4〉Mo7W1C4〉Mo7Cr1C4〉 Mo6W2C4〉 Mo8C4.Mo6W1Cr1C4 shows the highest stability,deformation resistance and hardness.G/B（shear modulus/bulk modulus）and Poisson′s ratio of the stable hexa-（Mo,Cr,W）2C are all larger than 1.75 and 0.26,respectively,which indicates that they are all brittle.The anisotropies are mainly due to the different Vogit shear modulus/Reuss shear modulus;the mechanical anisotropy of Mo7Cr1C4 is the largest,and that of Mo8C4 is the smallest.Moreover,the obtained Debye temperatureΘDand heat capacity Cpindicate that Mo6W2C4 possesses the best thermal conductivity（ΘD=497.72K）,while Mo7Cr1C4 and Mo6W2C4possess the largest heat capacity when the temperature is in the range of 0-10 Kand larger than 10 K,respectively.From the electronic property analysis,the doped Cr and W atoms can not only participate in orbitals hybridization themselves but also enhance the orbitals hybridization between Mo and C atoms,which can reinforce the interatomic interactions.
基金financially supported by the National Natural Science Foundation of China(No.51103125)the China Postdoctoral Science Foundation(No.2015M570483)+1 种基金the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,the Natural Science Foundation of Yangzhou(No.YZ2014043)the Science Innovative Foundation of Yangzhou University(No.2014CXJ017)
文摘Single-phase SrM ultrafine powders with single-domain particle ranging from 200 to 400 nm in size were successfully synthesized by a cetyltrimethylammonium bromide（CTAB）-as sis ted co-precipitation method,and excellent magnetic properties with saturation magnetization of 68.6 A·m^2·kg^（-1） and coercive field of 0.5250 T are obtained.As CTAB content exceeds 5.0 wt%,the impurities emerge due to the deterioration of simultaneous precipitations of the starting materials and the deviation of Sr/Fe molar ratio from stoichiometry ratio in the local microdomains by employing CTAB in co-precipitation process.Also,the use of CTAB can effectively improve the homogeneities of Fe-precursor particles with Sr-precursor particles,exert surface barriers to inhibit interdiffusion,and constrain the crystal growth in the local microdomains during sintering,resulting in smaller particle sizes and more uniform particle size distribution.
文摘The relationship between the graft yield and the effect of hexafiuorobutyl methacrylate graft treatment on the structural changes of the silk fibers was studied on the basis of the results of scanning electron micrograph photographs （SEM）, infrared spectroscopy （IR）, Raman spectrum, wide-angle X-ray diffraction patterns （WAXD）, nuclear magnetic resonance（NMR） and amion acid analysis. The results showed that the crystalline regions of grafted fibers were hardly affected and the fiber fission occurred on the cross sections of grafted fibers. The surface of fibers was covered with a high polymer film. The Raman spectrum showed there was little change in the conformation of grafted fibers which mainly remained β-sheet conformation. The IR of the grafted silk fibers showed new absorption of bands occurred which belonged to the stretching-vibrationabsorption-peak bands of Vo-o and VC-F of aliphatic ester species. The CF3-, -CF2- and -CFH- grafted silk macromodecul were verified in the NMR spectrum. The amion acid analysis indicated fluoride monomers were inclined to graft with TYR, ARG and CLU silk fibers.
基金Supported by the Youth Foundation of Jiangxi Provincial Office of Education (GJJ09605)the Science Foundation of Jiangxi Provincial Office of Education (GJJ09637)
文摘Hydrothermal reaction of MgCl2 and ethyl tetrazolate-5-carboxylate at 160 ℃unexpectedly yielded compound {（H3O）[Mg（H2O）6]Cl3} （1）. The result of X-ray diffraction analysis indicates that 1 crystallizes in the monoclinic system, space group C2/c with a = 9.2896（3）, b = 9.5570（4）, c = 13.3169（5） A, β = 90.1221（12）°, V= 1182.28（8） A3, Z = 4, Mr = 257.78, Dc = 1.448 g/cm3, μ = 0.824 mm^-1, F（000） = 536, R = 0.0265 and wR - 0.0706. 1 is composed of one hexa-aqua-magnesium（Ⅱ） ion, one hydroxonium ion, and three chlorine anions. These three components weave a perfect three-dimensional （3D） （4,4,6,12）-connected hydrogen bonding network within 1.
基金Project supported by the National Natural Science Foundation of China （No. 20272051） and the Teaching and Research Award Program for 0utstanding Young Teachers in Higher Education Institutions of Ministry of Education, China.Acknowledgments：The authors thank Dr. Gu Jian-Min for X-ray dif- fraction analysis.
文摘A rapid and facile synthesis of N-substituted 2,3,3a,4,7,7a-hexahydroisoindole-l,3-dione derivatives via microwave-promoted Beller three-component domino reaction of α,β,-unsaturated aldehydes, amides and N-substituted maleimides was described.
