Spatiotemporal dynamics induced by nonlocal competition in a diffusive predator-prey system with habitat complexity

Nonlinear Dynamics - In this paper, we study a delayed diffusive predator–prey model with nonlocal competition in prey and habitat complexity. The local stability of coexisting equilibrium is...     

Dynamic thermo-mechanical coupled simulation of statistically inhomogeneous materials by statistical second-order two-scale method

In this paper,a statistical second-order twoscale(SSOTS) method is developed to simulate the dynamic thcrmo-mechanical performances of the statistically inhomogeneous materials.For this kind of composite material,the random distribution characteristics of particles,including the shape,size,orientation,spatial location,and volume fractions,are all considered.Firstly,the repre.sentation for the microscopic configuration of the statistically inhomogeneous materials is described.Secondly,the SSOTS formulation for the dynamic thermo-mechanical coupled problem is proposed in a constructive way,including the cell problems,effective thermal and mechanical parameters,homogenized problems,and the SSOTS formulas of the temperatures,displacements,heat flux densities and stresses.And then the algorithm procedure corresponding to the SSOTS method is brought forward.The numerical results obtained by using the SSOTS algorithm are compared with those by classical methods.In addition,the thermo-mechanical coupling effect is studied by comparing the results of coupled case with those of uncoupled case.It demonstrates that the coupling effect on the temperatures,heat flux densities,displacements,and stresses is very distinct.The results show that the SSOTS method is valid to predict the dynamic thermo-mechanical coupled performances of statistically inhomogeneous materials.     

Sustained and Controlled Release of Volatile Precursors for Chemical Vapor Deposition of Graphene at Atmospheric Pressure

Precursors and catalysts play vital roles in chemical reactions. Considerable efforts have been devoted to the investigation of catalysts for graphene growth by chemical vapor deposition in recent years. However, there has been little research on precursors because of a lack of innovation in term of creating a controllable feeding method. Herein, we present a novel sustained and controlled release approach, and develop a convenient, safe, and potentially scalable feeding system with the assistance of matrix materials and a simple portable feeder. As a result, a highly volatile liquid precursor can be fed accurately to grow large-area, uniform graphene films with optimal properties. This feeding approach will further benefit the synthesis of other two-dimensional materials from various precursors.     

Unbridged bidentate aluminum complexes supported by diaroylhydrazone ligands: Synthesis,structure and catalysis in polymerization of ε-caprolactone and lactides

A series of novel diaroylhydrazone aluminum complexes have been synthesized and well-defined structurally, and their catalytic performance in the polymerization of ε-caprolactone and lactides have also been evaluated. Complexes [(L^1–4)₂AlMe] ( 1 – 4 ) {[L¹ = (3,5-^tBu₂–2-OMe-C₆H₂)CH=NNCOC₆H₅], [L² = (3,5-^tBu₂–2-OMe-C₆H₂)CH=NNCO(C₆H₄–4-OCH₃)], [L³ = (3,5-^tBu₂–2-OMe-C₆H₂)CH=NNCO(C₆H₄–4-Br)] and [L⁴ = (2-OMe-C₆H₄)CH=NNCO(C₆H₄–4-^tBu)]} were prepared through treatment of AlMe₃ with the corresponding proligands L^1–4H in molar ratios of 1: 1 or 1: 2. Chemical structures of all the complexes were well-defined by elemental analysis, NMR spectra as well as single-crystal X-ray study. Complexes [(L^1–4)₂AlMe] ( 1 – 4 ) in this work represent the first examples of aluminum complexes of aroylhydrazone ligands with crystallographic characterization. Specifically, they are all in monomeric form with a penta-coordinated aluminum center, including two approximately co-planar five-membered metallacycles with aluminum. Introduced bulky tert-butyl substituents in aroylhydrazone ligands could affect the geometry around the central metal which is a distorted square-based pyramid in complexes 1 – 3 while being a trigonal bipyramidal in complex 4 , thus affecting their catalytic behaviors. The complexes can successfully catalyze the ring-opening polymerization of ε-caprolactone and _L-lactide under mild conditions without any activator. In addition, complexes 1 – 4 could also polymerize rac-lactide, affording atactic polylactides with high conversions and good controllability in relatively short reaction time.     

Novel identification approach for nonlinear systems with hysteresis

Nonlinear Dynamics - A new identification approach for a nonlinear system with hysteresis, namely a cascading Bouc–Wen hysteresis model with linear dynamics, is proposed in this study. The...     

Theoretical investigation into coordination and selectivity of uranyl-unilateral benzotriazole salophens (X = O/S) for R/S-triadimefons

The design of new uranyl-ligands (uranyl-Ls) is of great significance for the separation and utilization of uranium. In this paper, the triazole group was introduced into uranyl-salophen (uranyl-S) to form new asymmetric uranyl-unilateral benzotriazole salophen (uranyl-UBS); we further replaced two oxygen atoms of uranyl-UBS with two sulfur atoms to generate uranyl-unilateral benzotriazole thio-salophen (uranyl-UBTS) as a new receptor. Then, we comprehensively explored coordination models of uranyl-UBS and uranyl-UBTS with R/S-triadimefons (R/S-TDFs) enantiomers as the guests using density functional theory calculations at the B3LYP//RECP/6-311G** level; we then investigated enantioselectivity recognition of the new receptors to the guests R/S-TDFs. The results indicated that the uranium atoms of the receptors uranyl-S, uranyl-UBS and uranyl-UBTS could coordinate with the carbonyl oxygens in guests R/S-TDFs to form complexes of guest-receptors R/S-TDFs-uranyl-Ls that exhibited two stable V-shaped structures with quite different properties. It was found that the coordination ability to the guests R/S-TDFs is uranyl-UBTS > uranyl-UBS > uranyl-S, while the enantioselectivity for the guests is uranyl-UBTS > uranyl-S > uranyl-UBS and, when the receptor is the same, R-TDF has stronger coordination ability than S-TDF. These results provide information and theoretical supports for the experiments of asymmetric uranyl-UBS with R/S-TDFs, and produce a reference for further exploring the coordination characteristics of asymmetric uranyl-salophen with the triazole derivatives.     

细胞松弛素B阻断微核法鉴定男性个体辐射敏感性的方法初探

初步研究了男性个体辐射敏感性的鉴定方法及标准。采集50名男性志愿者的外周血，分别给予不同剂量X射线照射，采用细胞松弛素B阻断双核法测定微核率(MNF)，通过二阶多项拟合法，绘制微核剂量效应选项中心标准曲线，将个人微核剂量效应曲线与标准曲线比对后判断个体辐射敏感性。 $0.0\sim2.5 $ Gy剂量范围内，剂量效应二阶多项拟合的中心方程为(MNF=0.014 7+0.036 2D+0.023 1D 2， r=0.726)。50名志愿者中，辐射敏感的有13人，辐射抗性的有14人，基本符合正态分布。Spearman秩和相关分析结果显示，MNF在各个辐射剂量点与辐射敏感性均存在正相关,与辐射抗性呈负相关,MNF随剂量增加而增加。本研究初步建立了“以线代点”男性个体辐射敏感性鉴定方法,并发现男性外周血淋巴细胞的本底微核率与个体辐射敏感性呈正相关。     

Conversion of carbohydrates into furfural and 5-hydroxymethylfurfural using furfuryl alcohol resin-based solid acid as catalyst

Cellulose - A furfuryl alcohol resin-based solid acid (SC-FAR-800) was prepared and applied in the conversion of carbohydrates into furan platform compounds in microwave. The results showed that...     

Existence of multi-bump solutions for a system with critical exponent in RN

We consider the following system with critical exponent in ${\mathbb{R}}^N$:$\{\begin{array}{c}?\mathrm{\Delta }u=K_1(y)u^{2^{?}?1}+\frac{p}{2^{?}}V(y)u^{p?1}{v}^q\text{in}{\mathbb{R}}^N,\hfill \\ ?\mathrm{\Delta }v=K_2(y)v^{2^{?}?1}+\frac{q}{2^{?}}V(y)u^p{v}^{q?1}\text{in}{\mathbb{R}}^N,\hfill \\ u,v>0,y\in {\mathbb{R}}^N,\hfill \end{array}$ where $N\ge 5$, $p,q>1$ and $p+q=2^{?}=\frac{2N}{N?2}$. Using finite dimensional reduction method, we prove the existence of multi-bump solutions. Their bumps can be placed on arbitrarily many or even infinitely many lattice points in ${\mathbb{R}}^N$. Since $p<2$ or $q<2$, we introduce two new norms to avoid singularity.