Blow‐up phenomena for a semilinear parabolic equation with weighted inner absorption under nonlinear boundary flux

Blow‐up phenomena for a nonlinear divergence form parabolic equation with weighted inner absorption term are investigated under nonlinear boundary flux in a bounded star‐shaped region. We assume some conditions on weight function and nonlinearities to guarantee that the solution exists globally or blows up at finite time. Moreover, by virtue of the modified differential inequality, upper and lower bounds for the blow‐up time of the solution are derived in higher dimensional spaces. Three examples are presented to illustrate applications of our results. Copyright © 2016 John Wiley & Sons, Ltd.     

Learning dynamic causal relationships among sugar prices

In this paper, we are interested in exploring the dynamic causal relationships among two sets of three variables in different quarters. One set is futures sugar closing price in Zhengzhou futures exchange market (ZC), spot sugar price in Zhengzhou (ZS) and futures sugar closing price in New York futures exchange market(NC) and the other includes futures sugar opening price in Zhengzhou (ZO), ZS and NC. For each quarter, we first use Bayesian model selection to obtain the optimal causal graph with the highest BD scores and then use Bayesian model averaging approach to explore the causal relationship between every two variables. From the real data analysis, the two conclusions almost coincide, which shows that the two methods are practical.     

Blow‐up of the smooth solutions to the compressible Navier–Stokes equations

In this paper, we will firstly extend the results about Jiu, Wang, and Xin (JDE, 2015, 259, 2981–3003). We prove that any smooth solution of compressible fluid will blow up without any restriction about the specific heat ratio γ. Then we prove the blow‐up of smooth solution of compressible Navier–Stokes equations in half space with Navier‐slip boundary. The main ideal is constructing the differential inequality. Copyright © 2017 John Wiley & Sons, Ltd.     

Regioselective alkali metal reduction of dibenzocyclooctadiene lignan derivatives,demethoxylation followed by dehalogenation

The regioselective demethoxylation and dehalogenation of dihalogenated dibenzocyclooctadiene lignans derivatives were realized in a one-step reaction with excellent yields in the sodium and t-butanol reaction system.     

一个高度灵敏和高选择性铝离子比率探针的合成及应用

本文构建了一种基于3-苯丙噻唑基-2-羟基-5-甲基苯甲醛的荧光探针用于检测铝离子。该荧光探针能够灵敏、高选择性地检测铝离子,并显示出颜色和强烈的荧光变化双重响应。研究结果表明,该探针对铝离子表现出非常好的荧光增强效果,检测过程中其它金属离子不会对检测结果产生明显的干扰。其比率荧光强度(I490/I567)与铝离子的浓度(0~20μmol/L)之间具有良好的线性关系,检测限低至0.5μmol/L。由于具有高效的选择性,该探针可以用于检测污染河水中的铝离子含量。     

Comparable charge transport property based on S…S interactions with that of π-π stacking in a bis-fused tetrathiafulvalene compound

Compact molecular packing with short π-π stacking and large π-overlap in organic semiconductors is desirable for efficient charge transport and high carrier mobility.Thus charge transport anisotropy along different directions is commonly observed in organic semiconductors.Interestingly,in this article,we found that comparable charge transport property were achieved based on the single crystals of a bis-fused tetrathiafulvalene derivative(EM-TTP) compound along two interaction directions,that is,the multiple strong S…S intermolecular interactions and the π-π stacking direction,with the measured electrical conductivity and hole mobility of 0.4 S cm~(-1),0.94 cm~2 V~(-1) s~(-1) and 0.2 S cm~(-1),0.65 cm2 V~(-1) s~(-1),respectively.This finding provides us a new molecular design concept for developing novel organic semiconductors with isotropic charge transport property through the synergistic effect of multiple intermolecular interactions(such as S…S interactions) and π-π stacking.     

Rigidity of complete manifolds with parallel Cotton tensor

The aim of this paper is to show some rigidity results for complete Riemannian manifolds with parallel Cotton tensor. In particular, we prove that any compact manifold of dimension \(n\ge 3\) with parallel Cotton tensor and positive constant scalar curvature is isometric to a finite quotient of \({\mathbb {S}}^n\) under a pointwise or integral pinching condition. Moreover, a rigidity theorem for stochastically complete manifolds with parallel Cotton tensor is also given. The proofs rely mainly on curvature elliptic estimates and the weak maximum principle.     

A Metal–Organic Compound as Cathode Material with Superhigh Capacity Achieved by Reversible Cationic and Anionic Redox Chemistry for High-Energy Sodium-Ion Batteries

Although sodium-ion batteries (SIBs) are considered as alternatives to lithium-ion batteries (LIBs), the electrochemical performances, in particular the energy density, are much lower than LIBs. A metal–organic compound, cuprous 7,7,8,8-tetracyanoquinodimethane (CuTCNQ), is presented as a new kind of cathode material for SIBs. It consists of both cationic (Cu^II↔Cu^I) and anionic (TCNQ⁰↔TCNQ⁻↔ TCNQ²⁻) reversible redox reactions, delivering a discharge capacity as high as 255 mAh g⁻¹ at a current density of 20 mA g⁻¹. The synergistic effect of both redox-active metal cations and organic anions brings an electrochemical transfer of multiple electrons. The transformation of cupric ions to cuprous ions occurs at near 3.80 V vs. Na⁺/Na, while the full reduction of TCNQ⁰ to TCNQ⁻ happens at 3.00–3.30 V. The remarkably high voltage is attributed to the strong inductive effect of the four cyano groups.     

一维六方准晶压电材料中幂函数型曲线裂纹的反平面问题

依据一维六方准晶压电材料反平面问题的基本方程,利用复变函数方法,通过引入适当的保角映射,研究了一维六方准晶压电材料中幂函数型曲线裂纹的反平面问题,并利用Cauchy积分理论,得到电不可通和电可通边界条件下的应力场和位移场的复表示以及裂纹尖端场强度因子的解析表达式.     

浅析几类双输入排队系统模型

从矩阵几何解的角度出发,分析了七种类型的Geom/Geom/(Geom/Geom)/H 双输入排队系统.对这几个模型进行了描述,使用拟生灭过程探讨了各类模型的矩阵结构,并给出了其状态转移概率矩阵.