Nonlinear singular traveling waves in a slightly compressible thermo-hyperelastic cylindrical shell

Nonlinear Dynamics - In this paper, we present a novel methodology for nonlinear dynamic analysis of chemical processes that are posed as differential–algebraic equations (DAE) systems. With...     

Finite time consensus control for nonlinear heterogeneous multi-agent systems with disturbances

Nonlinear Dynamics - This paper discusses the finite time consensus (FTC) issue of nonlinear heterogeneous multi-agent systems (HMASs) by combining integral sliding-mode control (SMC),...     

Two types of rare earth–organic frameworks constructed by racemic tartaric acid

Hydrothermal reactions of rare earth oxides with racemic tartaric acid (H₂tar) yielded 7 rare earth(III) MOFs with general formulas [R₂(tar)₃(H₂O)₂]_n (R=Y (1), Sm (4), Eu (5), Tb (6), Dy (7)) and [R₂(tar)₂(C₂O₄)(H₂O)₂]_n·4nH₂O (R=La (2), Nd (3)). X-ray powder diffraction analysis and single-crystal X-ray diffraction analysis reveal that they present two different structural types. MOFs 1, 4, 5, 6 and 7 are isostructural and crystallize in the orthorhombic non-centrosymmetric space group Iba2, and feature unusual fsc-3,4-Iba2 topology. MOFs 2 and 3 are isostructural and crystallize in monoclinic P2₁/c space group and display rare fsx-4,5-P2₁/c topology containing hydrophilic channels bounded by triple helical chains along a axis. MOFs 3, 4, 5, 6 and 7 exhibit intense lanthanide characteristic photoluminescence at room temperature.     

Vortex-lattice melting in magnesium diboride in terms of the elastic theory

In the framework of elastic theory, we study the vortex-lattice melting transitions in magnesium diboride for magnetic fields both parallel and perpendicular to the anisotropy axis. Using the parameters from experiments, the vortex-lattice melting lines in the H-T diagram are located systematically by various groups of Lindemann numbers. It is observed that the theoretical result for the vortex melting with parallel and perpendicular fields agrees well with the experimental data. Therefore, it is suggested that the phenomenological elastic theory is universal to various type-II superconductors, including two- and multi-band superconductors.     

Evolution of concentration fluctuation during phase separation of polystyrene/poly(vinyl methyl ether) blend in the presence of nanosilica

The influence of nanosilica on the concentration fluctuation of polystyrene/poly (vinyl methyl ether) (PS/PVME) mixtures was investigated during phase separation. The amplitude of concentration fluctuation was quantified by dielectric spectrums based on the idea of Lodge–Mcleish model and the linearized Cahn–Hilliard theory could describe the amplitude evolution of concentration fluctuation at the early stage of phase separation. Hydrophilic nanosilica A200 dispersed in PVME‐rich phase behaved an obvious inhibition effect on the concentration fluctuation of blend matrix, while hydrophobic nanosilica R974 dispersed in PS‐rich phase had little effect on the concentration fluctuation. The kinetics and amplitude evolution of concentration fluctuation during phase separation for PS/PVME/A200 nanocomposites were remarkably restrained due to the surface adsorption of PVME on A200. As the segmental dynamics of PVME and PS in homogeneous matrix was hardly influenced by A200 and R974, the enhanced miscibility and the significantly constrained flow relaxation of PVME chains might contribute to the retarded concentration fluctuation of PS/PVME/A200 nanocomposites. While the weak interaction between R974 and components of blend matrix and little effect of R974 on the molecular dynamics of PS chains may result in the weak retardation of concentration fluctuation for blend matrix. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1337–1349     

一类具有欧拉形式的中立型微分方程的振动性

研究具有欧拉形式的无界时滞中立型微分方程解的振动性，给出了方程振动的几个充分条件。     

Influence of NH<Subscript>3</Subscript> flow rate on pyridine-like N content and NO electrocatalytic oxidation of N-doped multiwalled carbon nanotubes

Nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs) have been prepared by pyrolysis of pyridine and iron phthalocyanine over an iron catalyst at 850 °C at various ammonia gas (NH₃) flow rates. X-ray photoelectron spectroscopy results reveal that the pyridine-like nitrogen (N) content can be controlled by changing the flow rate of NH₃, and that pyridine-like N plays an important role: it can increase the electrocatalytic activity and the rate of nitric oxide (NO) electrooxidation and decrease the activation energy of NO electrooxidation. Cyclic voltammetry results demonstrate that the N-MWCNTs sample grown with 200 mL/min NH₃ flow has the maximum N content of 3.22 atomic %, and its content of pyridine-like N that is chemically active is also the highest among all the N-MWCNTs samples. Electrochemical impedance spectroscopy results indicate that two-step electron transfer process occurs at the N-MWCNT-modified electrode, and the control step is different in various potential regions. The stability of NO electrooxidation at the N-MWCNT-modified electrode is examined, and the reaction mechanism is discussed.     

Efficient Heck cross-coupling of 3-iodo-benzopyrones with olefins under microwave irradiation without phosphine

An efficient and effective microwave-assisted Heck cross-coupling of different terminal olefins with various 3-iodo-benzopyrones including sterically hindered, electron-rich, electron-neutral, and electron-deficient is developed. It proceeded faster and generally gave good to excellent yields under microwave irradiation, phosphine-free, and air condition. The reaction could render this method particularly attractive for the efficient preparation of biologically and medicinally interesting molecules.     

Identification of functionally key residues in maltose transporter with an elastic network model-based thermodynamic method

Periplasmic binding protein-dependent maltose transport system (MBP-MalFGK₂) of Escherichia coli, an important member of the Adenosine triphosphate-binding cassette transporter superfamily, is in charge of the transportation of maltoses across cellular membrane. Studies have shown that this transport processes are activated by the binding of maltose and are accompanied by large-scale cooperative movements between different domains which are mediated by a network of important residues related to signal transduction and allosteric regulation. In this paper, the functionally crucial residues and long-range allosteric pathway of the regulation of the system by substrate were identified by utilising a coarse-grained thermodynamic method proposed by our group. The residues whose perturbations markedly change the binding free energy between maltoses and MBP-MalFGK₂ were considered to be key residues. In result, the key residues in 62 clusters distributed in different subdomains were identified successfully, and the results from our calculation are highly consistent with experimental and theoretical observations. Furthermore, we explored the long-range cooperation within the transporter. These studies will help us better understand the physical mechanism of the effects of the maltose on MBP-MalFGK₂ by long-range allosteric modulation.