Quantum Cosmology in CGBD Theory

We apply the theory developed in quantum cosmology to a model of charged generalized Brans–Dicke gravity. This is a quantum model of gravitation interacting with a charged Brans–Dicke type scalar field which is considered in the Pauli frame. The Wheeler–DeWitt equation describing the evolution of the quantum Universe is solved in the semiclassical approximation by applying the WKB approximation. The wave function of the Universe is also obtained by applying both the Vilenkin-like and the Hartle–Hawking-like boundary conditions. We then make predictions from the wave functions and infer that the Vilenkin's boundary condition is more reasonable in the Brans–Dicke gravity models leading a large vacuum energy density at the beginning of the inflation.     

基于自由基配体的Dy(Ⅲ)配合物的设计、合成、结构及磁性

以氮氧自由基为配体,合成了2例未见文献报道的氮氧自由基-稀土配合物[Dy（hfac）₃（NIT-C₃H₅）（H₂O）]与[Dy（hfac）₃（NIT-C₃H₅）]_n（hfac=六氟乙酰丙酮,NIT-C₃H₅=2-环丙烷基-4,4,5,5-四甲基-2-咪唑啉-3-氧化-1-氧基自由基）。单晶结构分析表明配合物1为单核结构,单斜晶系P2₁/c空间群;配合物2为一维结构,单斜晶系P2₁/c空间群。交流磁化率测试结果表明配合物2虚部表现出频率依赖,这表明配合物2是单链磁体。     

纳米镍钴铁氧体空心微球的制备与性能

以乙二醇为溶剂,氯化铁、氯化钴、氯化镍和醋酸铵为反应试剂,采用溶剂热法制备纳米Ni_xCo_1-xFe₂O₄(x=0、0.3、0.5、0.7、1)铁氧体空心微球,研究镍含量对铁氧体空心球的磁性与吸波性能的影响。借助X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、振动样品磁强计(VSM)和网络分析仪对试样的物相组成、微观形貌和电磁特性进行表征。结果表明制备的镍钴铁氧体为尖晶石结构,且形貌为空心球,粒径在200 nm左右。当x=0时,镍钴铁氧体空心球饱和磁化强度最大为81.7 emu·g^-1,反射损耗在1 658.8 MHz有最小值为-16.9 dB。     

Active Metabolites from the Fungus Pestalotiopsis sp. YMF1.0474

Chemistry of Natural Compounds - The chemical constituents of the fungus Pestalotiopsis sp. YMF1.0474 were studied. Five compounds, including a new pestalrone C (1) and four known compounds,...     

Size-dependent optical properties and carriers dynamics in CdSe/ZnS quantum dots

Size-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots （QDs） were investigated by two-colour femtosecond （fs） pump-probe （400/800 nm） and picosecond time-resolved photoluminescence （ps TRPL） experiments. Pump-probe measurement results show that there are two components for the excited carriers relaxation, the fast one with a time constant of several ps arises from the Auger-type recombination, which shows almost particle sizeindependence. The slow relaxation component with a time constant of several decades of ns can be clearly determined with ps TRPL spectroscopy in which the slow relaxation process shows strong particle size-dependence. The decay time constants increase from 21 to 34 ns with the decrease of particle size from 3.2 to 2.1 nm. The room-temperature decay lifetime is due to the thermal mixing of bright and dark excitons, and the size-dependence of slow relaxation process can be explained very well in terms of simple three-level model.     

Topological Aspects of Liquid Crystals

Using -mapping method and topological current theory, the properties and behaviors of disclination points in three-dimensional liquid crystals are studied. By introducing the strength density and the topological current of many disclination points, the total disclination strength is topologically quantized by the Hopf indices and Brouwer degrees at the singularities of the general director field when the Jacobian determinant of the general director field does not vanish. When the Jacobian determinant vanishes, the origin, annihilation, and bifurcation of disclination points are detailed in the neighborhoods of the limit point and bifurcation point, respectively. The branch solutions at the limit point and the different directions of all branch curves at the first- and second-order degenerated points are calculated. It is pointed out that a disclination point with a higher strength is unstable and will evolve to the lower strength state through the bifurcation process. An original disclination point can split into at most four disclination points at one time.     

Mass Density of Dp-branes

It is shown that the generally covariant definition of mass equals the ADM massfor Dp-branes.     

Synthesis and Crystal Structure of a New Penta-coordinated Cu(Ⅱ) Complex:Cu(C17H13F3O3)2·C5H5N

A new copper(Ⅱ) complex 3,Cu(C17H13F3O3)2·C5H5N,has been synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic,space group C2/c with a = 17.8511(7),b = 17.4136(7),c = 13.9425(7) ,β = 124.4830(10)°,V = 3572.5(3) 3,Z = 4,C39H29CuF6NO6,Mr = 785.17,F(000) = 1604,T = 292(2) K,Dc = 1.460 g/cm3 and μ = 0.691 mm-1. The structure was refined to R = 0.0477 and wR = 0.1110 for 2935 observed reflections with I > 2σ(I). For the title compound,X-ray analysis reveals that the copper(II) is penta-coordinated by four oxygen atoms from the corresponding 1-(4-(benzyloxy)phenyl)-4,4,4-trifluorobutane-1,3-dione ligands and one nitrogen atom of pyridine,forming a distorted square pyramidal geometry. It is found that the trifluoromethyl group,F(1)/F(1'),F(2)/F(2') and F(3)/F(3')),is disordered over two orientations in an approximate 3:1 ratio.     

V掺杂二维MoS_2体系气体吸附性能的第一性原理研究

以芥子气和沙林为代表的毒剂具有毒性强、扩散快的特点,是一类杀伤力强、难以防护的化学战剂,对其快速高效检测是一项具有挑战性的课题.本文基于第一性原理计算方法研究了V掺杂对二维MoS_2气敏性能影响的机理,发现V原子向二维MoS_2的掺杂过程为自发的放热反应, V原子可以稳定掺杂于二维MoS_2超胞结构中的S空位上.掺杂进入二维MoS_2体系的V原子作为施主中心向周围Mo原子给出电子,从而提高了材料的导电能力.吸附能、吸附距离和吸附过程中的电子转移计算结果表明V的掺杂提高了二维MoS_2对气体分子的吸附能力,增强了吸附质分子与基底表面的电子相互作用,从而提高了二维MoS_2的气敏性能.     

纳米镍钴铁氧体空心微球的制备与性能

以乙二醇为溶剂,氯化铁、氯化钴、氯化镍和醋酸铵为反应试剂,采用溶剂热法制备纳米Ni_xCo_1-xFe₂O₄(x=0、0.3、0.5、0.7、1)铁氧体空心微球,研究镍含量对铁氧体空心球的磁性与吸波性能的影响。借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、振动样品磁强计(VSM)和网络分析仪对试样的物相组成、微观形貌和电磁特性进行表征。结果表明制备的镍钴铁氧体为尖晶石结构,且形貌为空心球,粒径在200nm左右。当x=0时,镍钴铁氧体空心球饱和磁化强度最大为81.7emu·g^-1,反射损耗在1658.8MHz有最小值为-16.9dB。