YAlO3的体色与缺陷平衡的关系

利用固相扩散法在1 450 ℃下制备了YAlO₃粉末样品和陶瓷片样品,并在不同温度和不同气氛(air, O₂ or N₂)下对样品进行退火处理调制了其缺陷浓度。基于漫反射光谱和交流阻抗谱分析了YAlO₃样品的体色与其缺陷浓度之间的关系。研究结果表明YAlO₃具有p型导电机理,其浅棕色体色是由阳离子空位引起的。在高温和氮气氛下处理该材料其缺陷浓度减少,体色变浅。第一性原理计算结果认为YAlO₃中的主要缺陷应该是铝空位V_Al^×。     

Growth of Single-crystalline Transition Metal Dichalcogenides Monolayers with Large-size

Two-dimensional(2D) transition metal dichalcogenides(TMDCs) semiconductors, such as monolayers of molybdenum disulfide(MoS₂) and tungsten disulfide(WS₂) can potentially serve as ultrathin channel materials for building short channel field-effect transistors(FETs) to further extend Moore's Law. It is essential to develop controllable approaches for the synthesis of large single crystals of these 2D semiconductors to promote their practical applications in future electronics. In this short review, we summarized the recent advances on the chemical vapor deposition(CVD) of single crystalline semiconducting 2D TMDCs with a large size. We first discussed the driving force and urgent demands on developing controllable approaches for the growth of large 2D TMDCs single crystals and then summarized the current strategies and representative studies on the CVD growth of large 2D single crystals. Finally, we discussed the challenges and future directions in this topic.     

Delay-dependent exponential stability for impulsive Cohen–Grossberg neural networks with time-varying delays and reaction–diffusion terms

In this paper, a class of impulsive Cohen–Grossberg neural networks with time-varying delays and reaction–diffusion is formulated and investigated. By employing delay differential inequality and the linear matrix inequality (LMI) optimization approach, some sufficient conditions ensuring global exponential stability of equilibrium point for impulsive Cohen–Grossberg neural networks with time-varying delays and diffusion are obtained. In particular, the estimate of the exponential convergence rate is also provided, which depends on system parameters, diffusion effect and impulsive disturbed intention. It is believed that these results are significant and useful for the design and applications of Cohen–Grossberg neural networks. An example is given to show the effectiveness of the results obtained here.     

紧对称空间上Riesz平均的强逼近

本文在紧对称空间中给出了全测度集上Ｒｉｅｓｚ平均强逼近的阶     

Bifurcation analysis and chaos control of the modified Chua’s circuit system

From the view of bifurcation and chaos control, the dynamics of modified Chua’s circuit system are investigated by a delayed feedback method. Firstly, the local stability of the equilibria is discussed by analyzing the distribution of the roots of associated characteristic equation. The regions of linear stability of equilibria are given. It is found that there exist Hopf bifurcation and Hopf-zero bifurcation when the delay passes though a sequence of critical values. By using the normal form method and the center manifold theory, we derive the explicit formulas for determining the direction and stability of Hopf bifurcation. Finally, chaotic oscillation is converted into a stable equilibrium or a stable periodic orbit by designing appropriate feedback strength and delay. Some numerical simulations are carried out to support the analytic results.     

Structural characterization of ANGPTL8 (betatrophin) with its interacting partner lipoprotein lipase

Angiopoietin-like protein 8 (ANGPTL8) (also known as betatrophin) is a newly identified secretory protein with a potential role in autophagy, lipid metabolism and pancreatic beta-cell proliferation. Its structural characterization is required to enhance our current understanding of its mechanism of action which could help in identifying its receptor and/or other binding partners. Based on the physiological significance and necessity of exploring structural features of ANGPTL8, the present study is conducted with a specific aim to model the structure of ANGPTL8 and study its possible interactions with Lipoprotein Lipase (LPL). To the best of our knowledge, this is the first attempt to predict 3-dimensional (3D) structure of ANGPTL8. Three different approaches were used for modeling of ANGPTL8 including homology modeling, de-novo structure prediction and their amalgam which is then proceeded by structure verification using ERRATT, PROSA, Qmean and Ramachandran plot scores. The selected models of ANGPTL8 were further evaluated for protein–protein interaction (PPI) analysis with LPL using CPORT and HADDOCK server. Our results have shown that the crystal structure of iSH2 domain of Phosphatidylinositol 3-kinase (PI3K) p85β subunit (PDB entry: 3mtt) is a good candidate for homology modeling of ANGPTL8. Analysis of inter-molecular interactions between the structure of ANGPTL8 and LPL revealed existence of several non-covalent interactions. The residues of LPL involved in these interactions belong from its lid region, thrombospondin (TSP) region and heparin binding site which is suggestive of a possible role of ANGPTL8 in regulating the proteolysis, motility and localization of LPL. Besides, the conserved residues of SE1 region of ANGPTL8 formed interactions with the residues around the hinge region of LPL. Overall, our results support a model of inhibition of LPL by ANGPTL8 through the steric block of its catalytic site which will be further explored using wet lab studies in future.     

GLOBAL REGULARITY FOR MODIFIED CRITICAL DISSIPATIVE QUASI-GEOSTROPHIC EQUATIONS

We consider the n-dimensional modified quasi-geostrophic(SQG) equations δ_tθ + u·▽θ+kΛαθ=0, u = Λα-1R⊥θ with κ 0, α∈(0, 1] and θ0∈ W1,∞(Rn). In this paper, we establish a different proof for the global regularity of this system. The original proof was given by Constantin, Iyer, and Wu[5], who employed the approach of Besov space techniques to study the global existence and regularity of strong solutions to modified critical SQG equations for two dimensional case.The proof provided in this paper is based on the nonlinear maximum principle as well as the approach in Constantin and Vicol [2].     

A new cadinane sesquiterpenoid from cultures of the Basidiomycete Panus conchatus

A new cadinane sesquiterpenoid, named panutorulon A (1), was isolated from cultures of the basidiomycete Panus conchatus. The new structure was elucidated by means of spectroscopic methods. Compound 1 was tested for its cytotoxicity against five human cancer cell lines and for its inhibitory activity against isozymes of 11β-hydroxysteroid dehydrogenases (11β-HSD).     

Global well-posedness for 2D Boussinesq system with general supercritical dissipation

In this paper, we consider the 2D incompressible generalized Boussinesq system with the general supercritical dissipation. Using the Fourier localization method, we obtain the local and global well-posedness for the system, and give some blow-up criterion with the velocity or the temperature.     

A new tremulane sesquiterpenoid from the fungus Irpex lacteus

A new tremulane sesquiterpenoid, named irlactam A (1), was isolated from cultures of the fungus Irpex lacteus. The new structure was elucidated by spectroscopic data analysis. The compound was tested for its cytotoxicities on HL-60, SMMC-7721, A-549, MCF-7, and SW480 cells and for its inhibitory activity against isozymes of 11β-hydroxysteroid dehydrogenases (11β-HSD).