Rigorous spectral representation of relativistic random phase approximation for finite nuclei

By using the rigorous spectral representation of relativistic random phase approximation, the low-lying excitation of finite nuclei and its longitudinal response function for quasielastic electron scattering are calculated in the σ-ω model of quantum hadrodynamics. It is shown that the reproduction of the correct order of the 1- and 3- excitation states of 16O is due to the contribution of the exchange vertex. There is no significant influence of the retardation effect on the low-lying excitation states. In contrast, the retardation effect plays an important role in the electron scattering process of nuclei. The theoretical longitudinal responses of 12C and 40Ca, including the contributions of the exchange vertex and the retardation effect, are suppressed and reproduce the experimental data better than the results excluding them.     

混合溶剂体系中牛肝β-半乳糖苷酶催化5-氟-2'-脱氧尿苷区域选择性半乳糖基化反应

研究了混合溶剂体系中有机溶剂种类和含量对牛肝β-半乳糖苷酶催化5-氟-2'-脱氧尿苷区域选择性半乳糖基化反应的影响.结果表明,在含10%(体积分数)有机溶剂体系中,该酶稳定性差,失活严重.减少有机溶剂含量可显著减轻其对该酶的毒害作用.然而,有机溶剂的添加对酶促糖基化反应的区域选择性的影响很小(均保持在99%以上).牛肝...     

The Edge Magnetization and Strip Phase of Graphene Quantum Dots with Long-Range Coulomb Interaction

We investigate the magnetism and optical absorption properties of charge neutral hexagonal graphene quantum dots （GODs） terminated with zigzag edges by using a tight-binding Hubbard type model for the 7r electrons. Within the Hartree Fock approximation and taking into account the long-range Coulomb interaction, our cal- culation yields a ferromagnetic ground state with magnetic moments localized on the edges for GODs, and also gives an antiferromagnetism state with the energy very c/ose to the ferromagnetism ground state. We find that both the ferromagnetic and the antiferrornagnetic states have stripe patterned charge density distributions as a result of the long-range Coulomb interaction. The optical conductivity for GQDs has an energy gap in the low frequency regime in contrast to the bulk neutral graphene sheet where a universal constant is approached.     

Syntheses and Crystal Structures of Three Novel Zn~Ⅱ-sulfonyldibenzoilate Coordination Polymers

Three coordination polymers based on the V-shaped 4,4＇-dicarboxybiphenyl sulfone （H2sdba） ligands, [Zn3（μ-OH）2（sdba）2]n·2nH2O 1, [Zn2（sdba）2（4,4＇-bipy）]n·2nH2O 2 and [Zn3（sdba）3（py）2]n·n（py）·nH2O 3 （4,4＇-bipy = 4,4＇-bipydine）, were hydrothermally synthesized and structurally characterized. Complex 1 features the 2D planes constructed by the sdba ligands linking infinite Zn-O-C SBUs. The 4,4＇-bipy ligands in 2 bridge the Zn^II-sdba chains into interpenetrated 2D planes. The 3D network of α-Po topology in 3 is built from tri-nuclear Zn3 units with a [Zn3（OOC）6] structure. The intense blue and yellow luminescence was observed in complexes 1～3 which may result from ligand-to-metal charge transfer （LMCT）.