Alternative quantization of the Hamiltonian in loop quantum cosmology

Since there are quantization ambiguities in constructing the Hamiltonian constraint operator in isotropic loop quantum cosmology, it is crucial to check whether the key features of loop quantum cosmology are robust against the ambiguities. In this Letter, we quantize the Lorentz term of the gravitational Hamiltonian constraint in the spatially flat FRW model by two approaches different from that of the Euclidean term. One of the approaches is very similar to the treatment of the Lorentz part of Hamiltonian in loop quantum gravity and hence inherits more features from the full theory. Two symmetric Hamiltonian constraint operators are constructed respectively in the improved scheme. Both of them are shown to have the correct classical limit by the semiclassical analysis. In the loop quantum cosmological model with a massless scalar field, the effective Hamiltonians and Friedmann equations are derived. It turns out that the classical big bang is again replaced by a quantum bounce in both cases. Moreover, there are still great possibilities for the expanding universe to recollapse due to the quantum gravity effect.     

Detection and Comparison of Structure and Function of Wild-type Pneumolysin and Its Novel Mutant PlyM2

Here is reported a novel pneumolysin(Ply) mutant(PlyM2) that addresses a long-standing problem for vaccine development in this field: detoxification of Ply in the premise of retaining antigenic integrity. Structure and function of wild-type Ply(PlyWT) and PlyM2 mutants were detected and compared. Their structures were not signi- ficantly different according to the analysis by thermal-dependent fluorescence spectroscopy and circular dichroism spectroscopy. PlyM2 was confirmed to have lost hemolytic activity and yet could induce neutralizing antibodies to prevent in vitro hemolysis by PlyWT and Streptococcus pneumoniae(S. pneumoniae). These results give support to PlyM2 to be a new protein antigen for inclusion in the development of an effective pneumococcal multiprotein vaccine.     

HL－1M装置杂质VUV辐射及Te观测

本文介绍了ＨＬ－１Ｍ装置等离子体杂质真空紫外辐射观测的初步结果。用类Ｌｉ离子谱线强度比法估计出Ｔｅ≈４００ｅＶ。镀膜后的ＣＥＭ探测器的灵敏度提高。杂质对装置放电有重要影响     

Hexatungstate subunit as building block in the hydrothermal synthesis of organic-inorganic hybrid materials: synthesis, structure and optical properties of Co2(bpy)6 (W6O19)2 (bpy=4,4′-bipyridine)

A hydrothermal reaction of WO₃, CoCl₂ and 4,4′-bipyridine, yields a novel organic-inorganic hybrid compound, Co₂(bpy)₆(W₆O₁₉)₂, at 170°C. X-ray single crystal structure determination reveals a two-dimensional covalent structure belonging to monoclinic crystal system, space group C2/c, with cell parameters a=19.971(4) Å, b=11.523(2) Å, c=16.138(3) Å, β=96.49(3)°, V=3690.0 Å³ and Z=2. The hexatungstate, [W₆O₁₉]²⁻, acts as a building block in bidentate fashion to bridge the Co(II) centers in the crystal structure. The title compound is found to have an optical energy gap of 2.2 eV from UV-Vis-NIR reflectance spectra.     

A novel hybrid crystal of chiral racemic complexes coexisting with two kinds of polyoxomolybdates: synthesis and structure of [Co(bpy)3]2[Mo6O19] [β-(H2Mo8O26)]·4H2O

A novel polyoxometalate-based organic-inorganic hybrid compound, [Co(bpy)₃]₂ [Mo₆O₁₉] [β-(H₂Mo₈O₂₆)]·4H₂O (1), have been hydrothermally synthesized and structurally characterized by elemental analysis, single-crystal X-ray diffraction, IR and X-ray photoelectron spectra. Compound 1 represents the first example that racemic complexes coexisting with two kinds of polyoxomolybdate anions in the same crystal architecture, which should be of rare chance that four kinds of complexes crystallizes into a compound.     

Dark energy interacting with dark matter in classical Einstein and loop quantum cosmology

The cosmological model of dark energy interacting with cold dark matter without coupling to the baryonic matter is studied in the background of both classical Einstein and loop quantum cosmology. We consider two types of interacting models. In the former model, the interaction is a linear combination of the densities of two dark sectors, while in the latter model, the interaction with a constant transfer rate depends only on the density of cold dark matter. It is shown that the dynamical results in loop quantum cosmology are different from those in classical Einstein cosmology for both of the two kinds of interacting models. Moreover, the form of the interaction significantly affects the dynamical results in both kinds of cosmology.     

The solvability of two linear matrix equations

The solvability conditions of the following two linear matrix equations (i)A₁X₁B₁ +A₂X₂B₂ +A₃X₃B₃ =C,(ii) A₁XB₁ =C₁ A₂XB₂ =C₂ are established using ranks and generalized inverses of matrices. In addition, the duality of the three types of matrix equations

(iii) A ₁ X ₁ B ₁+A ₂ X ₂ B ₂+A ₃ X ₃ B ₃+A ₄ X ₄ B ₄=C, (iv) A ₁ XB ₁=C ₁ A ₂ XB ₂=C ₂ A ₃ XB ₃=C ₃ A ₄ XB ₄=C ₄, (v) AXB+CXD=E are also considered.     

Synthesis,Characterization and Structure of [Fe(2,2′-bipy)<Subscript>3</Subscript>]<Subscript>2</Subscript>[α-Mo<Subscript>8</Subscript>O<Subscript>26</Subscript>]: An α-Octamolybdate-Supported Compound Formed During the Diffuse Process

The α-octamolybdate-supported compound: [Fe(2,2′-bipy)₃]₂[α-Mo₈O₂₆] has been unexpectedly synthesized during a diffuse process and characterized by the IR spectroscopy, UV–Vis diffuse reflectance spectroscopy and the single crystal X-ray diffraction. The title compound exhibits an interesting 3D honeycomb ‘host’ supramolecular network with 1D channels, in which only α-octamolybdate anions ‘guests’ reside. The title compound shows the anisotropic property and probably will be applied as a novel semiconductor in the future.