Beta Ti−35Nb sandwich-structured composites with various reinforcing layers were designed and produced using additive manufacturing(AM)to achieve a balance between light weight and high strength.The impact of reinforc...Beta Ti−35Nb sandwich-structured composites with various reinforcing layers were designed and produced using additive manufacturing(AM)to achieve a balance between light weight and high strength.The impact of reinforcing layers on the compressive deformation behavior of porous composites was investigated through micro-computed tomography(Micro-CT)and finite element method(FEM)analyses.The results indicate that the addition of reinforcement layers to sandwich structures can significantly enhance the compressive yield strength and energy absorption capacity of porous metal structures;Micro-CT in-situ observation shows that the strain of the porous structure without the reinforcing layer is concentrated in the middle region,while the strain of the porous structure with the reinforcing layer is uniformly distributed;FEM analysis reveals that the reinforcing layers can alter stress distribution and reduce stress concentration,thereby promoting uniform deformation of the porous structure.The addition of reinforcing layer increases the compressive yield strength of sandwich-structured composite materials by 124%under the condition of limited reduction of porosity,and the yield strength increases from 4.6 to 10.3 MPa.展开更多
Three kinds of different phases of Mg-xLi-1Al alloys with x=5 （full α LA51）, 9 （dual-phase LA91）, and 14 （rich-βLA141） were prepared by vacuum melting method. Their microstructure and damping capacities were i...Three kinds of different phases of Mg-xLi-1Al alloys with x=5 （full α LA51）, 9 （dual-phase LA91）, and 14 （rich-βLA141） were prepared by vacuum melting method. Their microstructure and damping capacities were investigated by optical microscopy, X-ray diffractometry, and dynamic mechanical analysis. The results show that the addition of Li changes the crystal structure of the alloys and causes new damping mechanisms to emerge. And the appearance of BCC structure makes the damping performance improved remarkably. The lower the elastic modulus is, the smaller the strain is and even the slower the acceleration is. The dual-phase alloy shows a better damping capacity while the temperature changes. Furthermore, all three alloys have two significant peaks：P1 caused by the movement of dislocations on the basal planes and P2 caused by the sliding of grain boundaries.展开更多
The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The ...The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The parameters and repulsive parameters of dif- ferent polymers and β-HMX, the mesoscopic structures of β-HMX-based polymer-bonded explosives at different temperatures have been studied. The results showed that the compat-ibility between β-HMX and vinylidenedifluoride （VDF）,β-HMX and chlorotrifluoroethylene （CTFE）, VDF and CTFE increased with increasing temperature. The temperature and mo-lar ratio of the polymers played an important role in wrapped process. And there exists the optimum temperature and molar ratio.展开更多
The amino acid composition and the biased auto-correlation function are considered as features, BP neural network algorithm is used to synthesize these features. The prediction accuracy of this method is verified by u...The amino acid composition and the biased auto-correlation function are considered as features, BP neural network algorithm is used to synthesize these features. The prediction accuracy of this method is verified by using the independent non-homologous protein database. It is shown that the average absolute errors for resubstitution test are 0.070 and 0.068 with the standard deviations 0.049 and 0.047 for the prediction of the content of α-helix and β-sheet respectively. For cross-validation test, the average absolute errors are 0.075 and 0.070 with the standard deviations 0.050 and 0.049 for the prediction of the content of α-helix and β-sheet respectively. Compared with the other methods currently available, the BP neural network method combined with the amino acid composition and the biased auto-correlation function features can effectively improve the prediction accuracy.展开更多
Nanofibrous pyrolusite （β-MnO2） was synthesized. The particle shape changes from nanofibers to nanoparticles after grinding, and the phase structure does not change. The local environment around the central mangane...Nanofibrous pyrolusite （β-MnO2） was synthesized. The particle shape changes from nanofibers to nanoparticles after grinding, and the phase structure does not change. The local environment around the central manganese ion has a slight change in nanoparticles related to nanofibers. Fourier transform infrared （FTIR） spectra showed that A2u mode frequency shifts from 514 cm-1 to 574 cm-1 to 617 cm-1 gradually while the particle shape and size change from long nanofibers to short fibers and to nanoparticles. The extra vibrational band that is unpredicted by factor group analysis originates from the contribution of A2u mode of the particles with different sizes and shapes in the studied sample. On the basis of Rietveld refinement analysis of XRD profiles and the FTIR spectra, we think that two kinds of MnO6 octahedral geometries, i.e., 4 long＋2 short and 4 short＋2 long, could exist in pyrolusites synthesized by different route. The maximum vibrational frequency in the FTIR spectra of pyrolusites is sensitive to these micro-structures. Assignment of four vibrational bands in the middle and far infrared region has been made.展开更多
The reaction of anhydrous YbCl3 with lithium b-diketiminate, LLi (L = N,N- diphenyl-2,4-pentanediimine anion), in 1:1 molar ratio in THF gave rise to the title complex LYbCl2(THF)2 1 which has been characterized by si...The reaction of anhydrous YbCl3 with lithium b-diketiminate, LLi (L = N,N- diphenyl-2,4-pentanediimine anion), in 1:1 molar ratio in THF gave rise to the title complex LYbCl2(THF)2 1 which has been characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pna21(#33) with a = 19.657(8), b = 9.581(4), c = 14.107(6) ? V = 2656.8(18) 3, Z = 4, C25H33N2O2Cl2Yb, Mr = 637.49, Dc = 1.594 g/cm3, F(000) = 1268.00 and m(MoKa) = 3.744mm-1. The final R and wR are 0.031 and 0.073 for 2596 observed reflections with I > 2s(I), respectively. The X-ray crystal structure analysis revealed that the center ytterbium(III) is bonded to two chloride anions, two oxygen atoms from two tetrahydrofuran molecules and one chelate ligand b-diketiminate to form a six-coordinate distorted octahedral geometry.展开更多
We investigate neutron star properties by constructing a chiral SU(3) spontaneous breaking Lagrangian and using relativistic mean-field approximation. The results show that condensate appears at some baryon densities...We investigate neutron star properties by constructing a chiral SU(3) spontaneous breaking Lagrangian and using relativistic mean-field approximation. The results show that condensate appears at some baryon densities, and hyperons and exist in neutron star matter at high density. In this model, neutron star's maximum mass is with corresponding radius about 8 km.展开更多
The structure of the piperidine derivative of elemene C20H33NCl3CCOOH was determined by Xray crystallography. The crystal belongs to the orthorhombic system, space group P212121, a=12.303(4), b=22.064(7), c=9.002(4),...The structure of the piperidine derivative of elemene C20H33NCl3CCOOH was determined by Xray crystallography. The crystal belongs to the orthorhombic system, space group P212121, a=12.303(4), b=22.064(7), c=9.002(4), V=2444(2)3, Z=4, Mr=450.88, Dc=1.23g/cm3, (MoK)=391cm-1, F(000)=960, Final R=0.050, Rw=0.067 for 2393 reflections I>3(I), GOF=1.91. The title compound is composed of trichloroacetate and the elemenyl piperidine cation. The latter contains two hexacyclic rings of elemene and piperidine, which adopt the chair conformations.\=展开更多
A high order single step β algorithm, a new direct integration algorithm is proposed for solution of equations of motion. Whenβ=0.5, the accuracy of displacement, velocity and acceleration is of forth order (a trunc...A high order single step β algorithm, a new direct integration algorithm is proposed for solution of equations of motion. Whenβ=0.5, the accuracy of displacement, velocity and acceleration is of forth order (a truncation error of Δ t 5), and the algorithm is unconditionally stable and has no arithmetic damping and no overshooting. When >0.5, and an arithmetic damping is adopted, the algorithm is again unconditionally stable with a third order accuracy (a truncation error of Δ t 4). The analyses run with typical examples show that the algorithm proposed has higher speed, higher precision and better properties than other direct integration methods, such as Wilson θ method and Newmark β method in analysing linear elastic responses and nonlinear earthquake responses.展开更多
An approach of using molinspiration calculations and molecular docking on PBPs （penicillin-binding proteins） and certain β-lactamases is employed to predict the molecular properties, bioactivity and resistance of n...An approach of using molinspiration calculations and molecular docking on PBPs （penicillin-binding proteins） and certain β-lactamases is employed to predict the molecular properties, bioactivity and resistance of newer and reference cephalosporins. The previously synthesized cephalosporins 1-8 and reference cephalosporins were subjected to extensive evaluations by calculating the molecular properties, drug-likeness scores on the bases of Lipinski＇s rule and bioactivity prediction using the method of molinspiration web-based software. The TPSA （topological polar surface area）, OH-NH interactions, n-violation and the molinspiration Log partition coefficient （miLogP） values were also calculated. The investigated cephalosporins were subjected to molecular docking study on PBPs （lpyy） and on β-lactamases produced by S. aureus, K. pneumonia, E. coil and P. auroginosa using 1-click-docking website. Molecular properties of 1-8 recorded higher ＂FPSA than cephalexin and were lower than the reference cephalosporins and do not fulfill the requirements for Lipinski＇s rule. Bioactivities of 1-8 were predicted to be less and their docking scores on PBPs were comparable to those of the reference cephalosporins, particularly ceftobiprole. The references recorded various docking scores on the above β-lactamases and as expected, cefiobiprole recorded the lowest scores on all β-lactarnases. Cephalosporins 1-8 recorded various docking scores on β-lactamases. Molecular docking studies on PBPs and β-lactamases are considered as very useful, reliable and practical approach for predicting the bioactivity scores and to afford some information about the stability and selectivity of the newly proposed cephalosporins against β-lactamases of certain pathogenic microbes, such as P. auroginosa and MRSA, by recording the relative docking scores in comparison with those of reference cephalosporins.展开更多
基金the Hunan Young Scientific Innovative Talents Program,China(No.2020RC3040)Outstanding Youth Fund of Hunan Natural Science Foundation,China(Nos.2021JJ20011,2021JJ40600,2021JJ40590)the National Natural Science Foundation of China(Nos.52001030,52204371)..
文摘Beta Ti−35Nb sandwich-structured composites with various reinforcing layers were designed and produced using additive manufacturing(AM)to achieve a balance between light weight and high strength.The impact of reinforcing layers on the compressive deformation behavior of porous composites was investigated through micro-computed tomography(Micro-CT)and finite element method(FEM)analyses.The results indicate that the addition of reinforcement layers to sandwich structures can significantly enhance the compressive yield strength and energy absorption capacity of porous metal structures;Micro-CT in-situ observation shows that the strain of the porous structure without the reinforcing layer is concentrated in the middle region,while the strain of the porous structure with the reinforcing layer is uniformly distributed;FEM analysis reveals that the reinforcing layers can alter stress distribution and reduce stress concentration,thereby promoting uniform deformation of the porous structure.The addition of reinforcing layer increases the compressive yield strength of sandwich-structured composite materials by 124%under the condition of limited reduction of porosity,and the yield strength increases from 4.6 to 10.3 MPa.
基金Project(NCET-11-0554)supported by the Program for New Century Excellent Talents in University,ChinaProject(2011BAE22B04)supported by the National Key Technology R&D Program,ChinaProject(51271206)supported by the National Natural Science Foundation of China
文摘Three kinds of different phases of Mg-xLi-1Al alloys with x=5 （full α LA51）, 9 （dual-phase LA91）, and 14 （rich-βLA141） were prepared by vacuum melting method. Their microstructure and damping capacities were investigated by optical microscopy, X-ray diffractometry, and dynamic mechanical analysis. The results show that the addition of Li changes the crystal structure of the alloys and causes new damping mechanisms to emerge. And the appearance of BCC structure makes the damping performance improved remarkably. The lower the elastic modulus is, the smaller the strain is and even the slower the acceleration is. The dual-phase alloy shows a better damping capacity while the temperature changes. Furthermore, all three alloys have two significant peaks：P1 caused by the movement of dislocations on the basal planes and P2 caused by the sliding of grain boundaries.
文摘The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The parameters and repulsive parameters of dif- ferent polymers and β-HMX, the mesoscopic structures of β-HMX-based polymer-bonded explosives at different temperatures have been studied. The results showed that the compat-ibility between β-HMX and vinylidenedifluoride （VDF）,β-HMX and chlorotrifluoroethylene （CTFE）, VDF and CTFE increased with increasing temperature. The temperature and mo-lar ratio of the polymers played an important role in wrapped process. And there exists the optimum temperature and molar ratio.
文摘The amino acid composition and the biased auto-correlation function are considered as features, BP neural network algorithm is used to synthesize these features. The prediction accuracy of this method is verified by using the independent non-homologous protein database. It is shown that the average absolute errors for resubstitution test are 0.070 and 0.068 with the standard deviations 0.049 and 0.047 for the prediction of the content of α-helix and β-sheet respectively. For cross-validation test, the average absolute errors are 0.075 and 0.070 with the standard deviations 0.050 and 0.049 for the prediction of the content of α-helix and β-sheet respectively. Compared with the other methods currently available, the BP neural network method combined with the amino acid composition and the biased auto-correlation function features can effectively improve the prediction accuracy.
文摘Nanofibrous pyrolusite （β-MnO2） was synthesized. The particle shape changes from nanofibers to nanoparticles after grinding, and the phase structure does not change. The local environment around the central manganese ion has a slight change in nanoparticles related to nanofibers. Fourier transform infrared （FTIR） spectra showed that A2u mode frequency shifts from 514 cm-1 to 574 cm-1 to 617 cm-1 gradually while the particle shape and size change from long nanofibers to short fibers and to nanoparticles. The extra vibrational band that is unpredicted by factor group analysis originates from the contribution of A2u mode of the particles with different sizes and shapes in the studied sample. On the basis of Rietveld refinement analysis of XRD profiles and the FTIR spectra, we think that two kinds of MnO6 octahedral geometries, i.e., 4 long＋2 short and 4 short＋2 long, could exist in pyrolusites synthesized by different route. The maximum vibrational frequency in the FTIR spectra of pyrolusites is sensitive to these micro-structures. Assignment of four vibrational bands in the middle and far infrared region has been made.
基金Supported by the National Natural Science Foundation of China (20072027) Department of Education of Jiangsu province and the Key Laboratory of Organic Synthesis of Jiangsu province
文摘The reaction of anhydrous YbCl3 with lithium b-diketiminate, LLi (L = N,N- diphenyl-2,4-pentanediimine anion), in 1:1 molar ratio in THF gave rise to the title complex LYbCl2(THF)2 1 which has been characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pna21(#33) with a = 19.657(8), b = 9.581(4), c = 14.107(6) ? V = 2656.8(18) 3, Z = 4, C25H33N2O2Cl2Yb, Mr = 637.49, Dc = 1.594 g/cm3, F(000) = 1268.00 and m(MoKa) = 3.744mm-1. The final R and wR are 0.031 and 0.073 for 2596 observed reflections with I > 2s(I), respectively. The X-ray crystal structure analysis revealed that the center ytterbium(III) is bonded to two chloride anions, two oxygen atoms from two tetrahydrofuran molecules and one chelate ligand b-diketiminate to form a six-coordinate distorted octahedral geometry.
基金The project supported in part by the Key Research Plan of Theoretical Physics and Cross Science under Grant No.90103018National Natural Science Foundation of China under Grant No.19975062
文摘We investigate neutron star properties by constructing a chiral SU(3) spontaneous breaking Lagrangian and using relativistic mean-field approximation. The results show that condensate appears at some baryon densities, and hyperons and exist in neutron star matter at high density. In this model, neutron star's maximum mass is with corresponding radius about 8 km.
文摘The structure of the piperidine derivative of elemene C20H33NCl3CCOOH was determined by Xray crystallography. The crystal belongs to the orthorhombic system, space group P212121, a=12.303(4), b=22.064(7), c=9.002(4), V=2444(2)3, Z=4, Mr=450.88, Dc=1.23g/cm3, (MoK)=391cm-1, F(000)=960, Final R=0.050, Rw=0.067 for 2393 reflections I>3(I), GOF=1.91. The title compound is composed of trichloroacetate and the elemenyl piperidine cation. The latter contains two hexacyclic rings of elemene and piperidine, which adopt the chair conformations.\=
文摘A high order single step β algorithm, a new direct integration algorithm is proposed for solution of equations of motion. Whenβ=0.5, the accuracy of displacement, velocity and acceleration is of forth order (a truncation error of Δ t 5), and the algorithm is unconditionally stable and has no arithmetic damping and no overshooting. When >0.5, and an arithmetic damping is adopted, the algorithm is again unconditionally stable with a third order accuracy (a truncation error of Δ t 4). The analyses run with typical examples show that the algorithm proposed has higher speed, higher precision and better properties than other direct integration methods, such as Wilson θ method and Newmark β method in analysing linear elastic responses and nonlinear earthquake responses.
文摘An approach of using molinspiration calculations and molecular docking on PBPs （penicillin-binding proteins） and certain β-lactamases is employed to predict the molecular properties, bioactivity and resistance of newer and reference cephalosporins. The previously synthesized cephalosporins 1-8 and reference cephalosporins were subjected to extensive evaluations by calculating the molecular properties, drug-likeness scores on the bases of Lipinski＇s rule and bioactivity prediction using the method of molinspiration web-based software. The TPSA （topological polar surface area）, OH-NH interactions, n-violation and the molinspiration Log partition coefficient （miLogP） values were also calculated. The investigated cephalosporins were subjected to molecular docking study on PBPs （lpyy） and on β-lactamases produced by S. aureus, K. pneumonia, E. coil and P. auroginosa using 1-click-docking website. Molecular properties of 1-8 recorded higher ＂FPSA than cephalexin and were lower than the reference cephalosporins and do not fulfill the requirements for Lipinski＇s rule. Bioactivities of 1-8 were predicted to be less and their docking scores on PBPs were comparable to those of the reference cephalosporins, particularly ceftobiprole. The references recorded various docking scores on the above β-lactamases and as expected, cefiobiprole recorded the lowest scores on all β-lactarnases. Cephalosporins 1-8 recorded various docking scores on β-lactamases. Molecular docking studies on PBPs and β-lactamases are considered as very useful, reliable and practical approach for predicting the bioactivity scores and to afford some information about the stability and selectivity of the newly proposed cephalosporins against β-lactamases of certain pathogenic microbes, such as P. auroginosa and MRSA, by recording the relative docking scores in comparison with those of reference cephalosporins.
