Cosmological implications of 5-dimensional Brans–Dicke theory

The five-dimensional Brans–Dicke theory naturally provides two scalar fields by the Killing reduction mechanism. These two scalar fields could account for the accelerated expansion of the universe. We test this model and constrain its parameter by using the type Ia supernova (SN Ia) data. We find that the best fit value of the 5-dimensional Brans–Dicke coupling constant is ω=−1.9. This result is also consistent with other observations such as the baryon acoustic oscillation (BAO).     

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.     

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.     

A newly synthesized organic–inorganic hybrid in nano-size including [BW12O40]5− anions and hydrolyzed 2-cyanoguanidine cations as a double working green catalyst

Research on Chemical Intermediates - A newly prepared nano-organic–inorganic hybrid compound, videlicet [HPDCD]5[BW12O40]·3H2O (HPDCD?=?hydrolyzed and protonated...     

Precursor criteria for noise-induced critical transitions in multi-stable systems

Nonlinear Dynamics - Predicting noise-induced critical transitions between multi-stable states of a dynamical system is of uttermost importance in various fields. This paper investigates a...     

多酸在电催化析氢反应中的应用研究进展

电催化水裂解是一种可持续用于生产可再生氢能源的技术。然而,开发高效稳定、低成本的析氢电催化剂仍是一项具有挑战性的任务。多金属氧酸盐(多酸)是一种离散的金属氧簇合物,通常由氧配体和高价的钒(V)、钼(VI)、钨(VI)金属构成。由于多酸含有丰富的氧化还原活性金属中心,因此,近几年来,多酸在水裂解应用研究方面备受关注。本综述将聚焦于多酸在电催化水裂解析氢的应用研究进展。本文还突出强调了电催化析氢目前面临的主要问题,以及对多酸基催化剂及作为催化剂前体在电催化析氢方面的应用及发展前景做了展望。     

Spontaneous Stepwise Self‐Assembly of a Polyoxometalate–Organic Hybrid into Catalytically Active One‐Dimensional Anisotropic Structures

An inorganic–organic hybrid surfactant with a hexavanadate cluster as the polar head group was designed and observed to assemble into micelle structures, which further spontaneously coagulate into a 1D anisotropic structure in aqueous solutions. Such a hierarchical self‐assembly process is driven by the cooperation of varied noncovalent interactions, including hydrophobic, electrostatic, and hydrogen‐bonding interactions. The hydrophobic interaction drives the quick formation of the micelle structure; electrostatic interactions involving counterions leads to the further coagulation of the micelles into larger assemblies. This process is similar to the crystallization process, but the specific counterions and the directional hydrogen bonding lead to the 1D growth of the final assemblies. Since most of the hexavanadates are exposed to the surface, the 1D assembly with nanoscale thickness is a highly efficient heterogeneous catalyst for the oxidation of organic sulfides with appreciable recyclability.     

Some equalities for estimations of variance components in a general linear model and its restricted and transformed models

For the unknown positive parameter σ² in a general linear model , the two commonly used estimations are the simple estimator (SE) and the minimum norm quadratic unbiased estimator (MINQUE). In this paper, we derive necessary and sufficient conditions for the equivalence of the SEs and MINQUEs of the variance component σ² in the original model ?, the restricted model , the transformed model , and the misspecified model .     

Path integral and effective Hamiltonian in loop quantum cosmology

We study the path integral formulation of Friedmann universe filled with a massless scalar field in loop quantum cosmology. All the isotropic models of $k=0,+1,-1$ are considered. To construct the path integrals in the timeless framework, a multiple group-averaging approach is proposed. Meanwhile, since the transition amplitude in the deparameterized framework can be expressed in terms of group-averaging, the path integrals can be formulated for both deparameterized and timeless frameworks. Their relation is clarified. It turns out that the effective Hamiltonian derived from the path integral in deparameterized framework is equivalent to the effective Hamiltonian constraint derived from the path integral in timeless framework, since they lead to same equations of motion. Moreover, the effective Hamiltonian constraints of above models derived in canonical theory are confirmed by the path integral formulation.