Phase pure and well crystalline Cr2AlB2 powders are synthesized by heating the mixtures of CrB and Al powders at 900~℃.Cr2AlB2 exhibits nanolaminated morphology which transforms from flake-like crystallite to needle-...Phase pure and well crystalline Cr2AlB2 powders are synthesized by heating the mixtures of CrB and Al powders at 900~℃.Cr2AlB2 exhibits nanolaminated morphology which transforms from flake-like crystallite to needle-like grain with the increase of holding time.The morphology-structure relationships of Cr2AlB2 are delicately discussed.Meanwhile,as the precursor for fabrication of Cr2AlB2,high purity CrB powders are also prepared by high-temperature reaction of B and Cr elemental powders at 1800℃.CrB grains grow into regular plate-like morphology.Through Rietveld structure refinement,new sets of diffraction data are presented for both CrB and Cr2AlB2 and overlapped peak positions and intensities are revealed which make up for the deficiency of the existing data in ICDD PDF#32-0277(CrB)and ICDD PDF#72-1847(Cr2AlB2).Moreover,since MAB phases are precursors for preparing MBenes,2D-CrBnanosheets are successfully prepared by completely etching out Al atomic layers from Cr2AlB2.2D-CrB crystalizes in CrB structure with two-dimensional lamellar morphology.Simultaneously the formation mechanism of 2D-CrB is vividly depicted.A system of materials preparation from CrB to Cr2AlB2 and then to 2D-CrB is well established.展开更多
In this communication, the possibility for the preparation of two-dimensional MBene CrB from MAB phase Cr2AlB2 is demonstrated for the first time. Herein M is a transition metal, A is a group IIIAor IVA element and B ...In this communication, the possibility for the preparation of two-dimensional MBene CrB from MAB phase Cr2AlB2 is demonstrated for the first time. Herein M is a transition metal, A is a group IIIAor IVA element and B is boron; MAB phases are layered transition metal ternary borides, MBene is used to emphasize the loss of A group element from the parent MAB phases and to highlight the 2 D nature. The possible 2 D CrB nano sheets are prepared by selectively etching out Al layers from Cr2AlB-2 by immersing the Cr2AlB2 powders in dilute HCl solution at room temperature. The as-prepared 2 D CrB nano sheets are examined using X-ray diffraction and scanning electron microscopy and energy dispersive X-ray spectroscopy（EDS）. In addition, different structure models are built to explain the observed phenomena.The discovery in this work opens a door to the synthesis of a large number of new 2 D MBenes from MAB phases.展开更多
The Moho interface provides critical evidence for crustal thickness and the mode of oceanic crust accretion. The seismic Moho interface has not been identified yet at the magma-rich segments （46°-52°E） of ...The Moho interface provides critical evidence for crustal thickness and the mode of oceanic crust accretion. The seismic Moho interface has not been identified yet at the magma-rich segments （46°-52°E） of the ultra- slow spreading Southwestern Indian Ridge （SWIR）. This paper firstly deduces the characteristics and do- mains of seismic phases based on a theoretical oceanic crust model. Then, topographic correction is carried out for the OBS record sections along Profile Y3Y4 using the latest OBS data acquired from the detailed 3D seismic survey at the SWIR in 2010. Seismic phases are identified and analyzed, especially for the reflected and refracted seismic phases from the Moho. A 2D crustal model is finally established using the ray tracing and travel-time simulation method. The presence of reflected seismic phases at Segment 28 shows that the crustal rocks have been separated from the mantle by cooling and the Moho interface has already formed at zero age. The 2D seismic velocity structure across the axis of Segment 28 indicates that detachment faults play a key role during the processes of asymmetric oceanic crust accretion.展开更多
After developing the mathematical means for the correspondence of classical phase-space function to quantum-mechanical operators with symmetrical ordering of the basic canonical operators in the sense of Weyl the appr...After developing the mathematical means for the correspondence of classical phase-space function to quantum-mechanical operators with symmetrical ordering of the basic canonical operators in the sense of Weyl the approach is applied to an infinite series of classical monomial functions of the canonical variables. These include as well as pure powers of the amplitude as also basic periodic functions of the phase φwith their quantum-mechanical correspondence. In the representation by number states, all the considered operators involve the Jacobi polynomials as the essential formative element. Whereas the quantity in normal ordering due to its indeterminacy leads to the introduction of the notions of sub- and super-Poissonian statistics the analogous quantity in (Weyl) symmetrical orderingis positive definite and satisfies an inequality. The notions of sub- and super-Poissonian statistics are problematic when they are used for the definition of nonclassicality of states since the mentioned measure in normal ordering does not determine the Poisson statistics in their middle in unique way but determines only a large set of statistics which may be very far in the sense of the Hilbert-Schmidt distance from a Poisson statistics that is discussed.展开更多
The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns （2D TRLS） has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in whi...The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns （2D TRLS） has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in which the secondary phase separation takes place. The results of the 2D TRLS provided more detailed information that was not readily observed in the 1D TRLS patterns. （i） During the first process of phase separation, the sequential order of coarsening in size of the domains among the larger and smaller ones has been reversed between the diffusion regime and the hydrodynamic regime. （ii） The change of the larger domains in size, due to the hydrodynamic flow in the late stage of the first phase separation process, keeps on taking place earlier than that of the new domains appeared in the secondary phase separation process. （iii） During the secondary phase separation process the size growth of the smaller domains takes place earlier than that of the larger ones, probably due to the assumption that the coarsening mode could decrease the interface tension more quickly.展开更多
The biaxial tensile tests were carried out to investigate the deformation behavior and yield loci of dual-phase （DP） steel sheets under biaxial tensile conditions. The true stress-true strain curves of DP steel shee...The biaxial tensile tests were carried out to investigate the deformation behavior and yield loci of dual-phase （DP） steel sheets under biaxial tensile conditions. The true stress-true strain curves of DP steel sheets for different loading ratios were obtained, and the experimental yield loci were determined based on the equivalent plastic work principle. The experimental yield loci were compared to the theoretical yield loci based on Hi1148, Hi1190, Hi1193, Hosford, Barlat89, Yld2000-2d and Gotoh yield criteria. It is found that Yld2000-2d yield criterion can describe the general trends of experimental yield loci of DP steel sheets with comparably higher accuracy. Hosford criterion has the maximum error for DP590, whereas Hi1148 and Barlat89 have the maximum errors for DP780 and DP980.展开更多
基金financial supports from the National Natural Science Foundation of China under grant No. 51672064, No. U1435206 and No. 61271049
文摘Phase pure and well crystalline Cr2AlB2 powders are synthesized by heating the mixtures of CrB and Al powders at 900~℃.Cr2AlB2 exhibits nanolaminated morphology which transforms from flake-like crystallite to needle-like grain with the increase of holding time.The morphology-structure relationships of Cr2AlB2 are delicately discussed.Meanwhile,as the precursor for fabrication of Cr2AlB2,high purity CrB powders are also prepared by high-temperature reaction of B and Cr elemental powders at 1800℃.CrB grains grow into regular plate-like morphology.Through Rietveld structure refinement,new sets of diffraction data are presented for both CrB and Cr2AlB2 and overlapped peak positions and intensities are revealed which make up for the deficiency of the existing data in ICDD PDF#32-0277(CrB)and ICDD PDF#72-1847(Cr2AlB2).Moreover,since MAB phases are precursors for preparing MBenes,2D-CrBnanosheets are successfully prepared by completely etching out Al atomic layers from Cr2AlB2.2D-CrB crystalizes in CrB structure with two-dimensional lamellar morphology.Simultaneously the formation mechanism of 2D-CrB is vividly depicted.A system of materials preparation from CrB to Cr2AlB2 and then to 2D-CrB is well established.
基金supports from the National Natural Science Foundation of China under grant No. 51672064 and No. U1435206the Beijing Municipal Science & Technology Commission under grant No. Z151100003315012 and No. D161100002416001
文摘In this communication, the possibility for the preparation of two-dimensional MBene CrB from MAB phase Cr2AlB2 is demonstrated for the first time. Herein M is a transition metal, A is a group IIIAor IVA element and B is boron; MAB phases are layered transition metal ternary borides, MBene is used to emphasize the loss of A group element from the parent MAB phases and to highlight the 2 D nature. The possible 2 D CrB nano sheets are prepared by selectively etching out Al layers from Cr2AlB-2 by immersing the Cr2AlB2 powders in dilute HCl solution at room temperature. The as-prepared 2 D CrB nano sheets are examined using X-ray diffraction and scanning electron microscopy and energy dispersive X-ray spectroscopy（EDS）. In addition, different structure models are built to explain the observed phenomena.The discovery in this work opens a door to the synthesis of a large number of new 2 D MBenes from MAB phases.
基金The National Natural Science Foundation of China under contract Nos 41176053,41076029,91028002 and 41176046Dayang 115 under contract No.DYXM-115-02-3-01
文摘The Moho interface provides critical evidence for crustal thickness and the mode of oceanic crust accretion. The seismic Moho interface has not been identified yet at the magma-rich segments （46°-52°E） of the ultra- slow spreading Southwestern Indian Ridge （SWIR）. This paper firstly deduces the characteristics and do- mains of seismic phases based on a theoretical oceanic crust model. Then, topographic correction is carried out for the OBS record sections along Profile Y3Y4 using the latest OBS data acquired from the detailed 3D seismic survey at the SWIR in 2010. Seismic phases are identified and analyzed, especially for the reflected and refracted seismic phases from the Moho. A 2D crustal model is finally established using the ray tracing and travel-time simulation method. The presence of reflected seismic phases at Segment 28 shows that the crustal rocks have been separated from the mantle by cooling and the Moho interface has already formed at zero age. The 2D seismic velocity structure across the axis of Segment 28 indicates that detachment faults play a key role during the processes of asymmetric oceanic crust accretion.
文摘After developing the mathematical means for the correspondence of classical phase-space function to quantum-mechanical operators with symmetrical ordering of the basic canonical operators in the sense of Weyl the approach is applied to an infinite series of classical monomial functions of the canonical variables. These include as well as pure powers of the amplitude as also basic periodic functions of the phase φwith their quantum-mechanical correspondence. In the representation by number states, all the considered operators involve the Jacobi polynomials as the essential formative element. Whereas the quantity in normal ordering due to its indeterminacy leads to the introduction of the notions of sub- and super-Poissonian statistics the analogous quantity in (Weyl) symmetrical orderingis positive definite and satisfies an inequality. The notions of sub- and super-Poissonian statistics are problematic when they are used for the definition of nonclassicality of states since the mentioned measure in normal ordering does not determine the Poisson statistics in their middle in unique way but determines only a large set of statistics which may be very far in the sense of the Hilbert-Schmidt distance from a Poisson statistics that is discussed.
基金supported by the National Natural Science of Foundation of China(NSFC)(Nos.20674014, 20425415,20274010,50103003,20221402)
文摘The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns （2D TRLS） has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in which the secondary phase separation takes place. The results of the 2D TRLS provided more detailed information that was not readily observed in the 1D TRLS patterns. （i） During the first process of phase separation, the sequential order of coarsening in size of the domains among the larger and smaller ones has been reversed between the diffusion regime and the hydrodynamic regime. （ii） The change of the larger domains in size, due to the hydrodynamic flow in the late stage of the first phase separation process, keeps on taking place earlier than that of the new domains appeared in the secondary phase separation process. （iii） During the secondary phase separation process the size growth of the smaller domains takes place earlier than that of the larger ones, probably due to the assumption that the coarsening mode could decrease the interface tension more quickly.
基金This research was funded by National Natural Science Foundation of China （51275026） and State Key Laboratory of Development and Application Technology of Automotive Steels （Bao Steel Y 12ECEQ07Y）.
文摘The biaxial tensile tests were carried out to investigate the deformation behavior and yield loci of dual-phase （DP） steel sheets under biaxial tensile conditions. The true stress-true strain curves of DP steel sheets for different loading ratios were obtained, and the experimental yield loci were determined based on the equivalent plastic work principle. The experimental yield loci were compared to the theoretical yield loci based on Hi1148, Hi1190, Hi1193, Hosford, Barlat89, Yld2000-2d and Gotoh yield criteria. It is found that Yld2000-2d yield criterion can describe the general trends of experimental yield loci of DP steel sheets with comparably higher accuracy. Hosford criterion has the maximum error for DP590, whereas Hi1148 and Barlat89 have the maximum errors for DP780 and DP980.
