Global exponential stability of a delay reduced SIR model for migrant workers’ home residence

The paper is concerned with a reduced SIR model for migrant workers. By using differential inequality technique and a novel argument, we derive a set of conditions to ensure that the endemic equilibrium of the model is globally exponentially stable. The obtained results complement with some existing ones. We also use numerical simulations to demonstrate the theoretical results.     

一系列基于混合配体策略构筑的金属有机骨架的合成、结构及性质

通过简单高效的醛酮缩合反应,合成了碱性配体2,6-二（4-吡啶基亚甲基）环己酮（BPCH）,采用3种芳香羧酸配体：对苯二甲酸（H₂TP）、间苯二甲酸（H₂IP）和均苯三甲酸（H₃TMA）,以混合配体策略制备了7例金属有机骨架（MOFs）。用单晶X射线衍射、红外光谱、粉末X射线衍射和热重分析对其进行表征并分析其拓扑结构。MOFs1、2、3均呈现为多样的三维结构,MOFs4~7表现为同构的二维结构。荧光测试结果显示该类化合物对Fe³⁺有较好的荧光猝灭效应,同时对于染料具有一定的吸附能力。     

水溶性二铁六羰基配合物与生物相关分子的相互作用及其促进一氧化碳释放

二铁六羰基配合物[Fe₂（μ-SCH₂R）₂（CO）6]（R=CH （OH） CH₂（OH）,1）是一个水溶性且能够释放一氧化碳的分子（CORM）,我们应用各种光谱技术研究了其与血红蛋白（Hb）、肌红蛋白（Mb）、牛血清白蛋白（BSA）、谷胱甘肽（GSH）和DNA等生物分子的相互作用。红外光谱结果表明,蛋白质和谷胱甘肽均能促进配合物1分解释放CO。该CO释放过程符合一级动力学模型,其中谷胱甘肽促进CO释放的效率最高。紫外吸收光谱变化和荧光猝灭效应也表明这些生物相关分子与二铁羰基配合物之间存在相互作用。蛋白质和配合物1的CD光谱结果显示,配合物没有引起蛋白质的构象变化。pUC19质粒DNA与配合物1之间的作用表明该配合物不会引起DNA损伤。     

Degradation of electrospun SF/P(LLA-CL) blended nanofibrous scaffolds in vitro

Nanofibrous scaffolds of silk fibroin (SF) and poly(l-lactic acid-co-?-caprolactone) (P(LLA-CL)) blends fabricated via electrospinning possessed good mechanical property and biocompatibility, as demonstrated by a previous study in vitro. However, the degradation behavior of the scaffolds, which may significantly influence tissue repair and regeneration, needs further exploration. In this study, in vitro degradation of pure SF, P(LLA-CL) and SF/P(LLA-CL) blended nanofibrous scaffolds were performed in phosphate-buffered saline (PBS, pH 7.4 ± 0.1) at 37 °C for 6 months. A series of analyses and characterizations (including morphologic changes, loss weight, pH changes of PBS solutions, DSC, XRD and FTIR-ATR) were conducted to the nanofibrous scaffolds after degradation and the results showed that the pure SF nanofibrous scaffolds were not completely degradable in PBS while pure P(LLA-CL) nanofibrous scaffolds had the fastest degradation rate. Moreover, the addition of SF reduced the degradation rate of P(LLA-CL) in SF/P(LLA-CL) blended nanofibrous scaffolds. This was probably caused by the intermolecular interactions between SF and P(LLA-CL), which hindered the movement of P(LLA-CL) molecular chains.     

可膨胀石墨阻燃高回弹聚氨酯泡沫塑料的性能

在原料中添加可膨胀石墨(EG),采用一步法合成了阻燃型高回弹聚氨酯软泡,研究了EG对泡沫性能的影响.用扫描电镜和光学显微镜观察了EG粒子在泡沫内的固着状态及其对泡孔形貌和泡沫燃烧后的炭层形貌的影响.垂直-水平燃烧实验和极限氧指数实验检测了EG的添加量对于泡沫燃烧的抑制情况.考察了EG粒子的含量对泡沫密度、拉伸及压缩力学...     

Stability of sets of functional differential equations with impulse effect

In this paper, we investigate stability of sets for a class of impulsive functional differential equations by using piecewise continuous Lyapunov functions with Razumickhin techniques. Some sufficient conditions for stability of sets are established, and some known stability theorems also are generalized.     

Exponential convergence for high-order recurrent neural networks with a class of general activation functions

In this paper, we consider high-order recurrent neural networks with a class of general activation functions. By using some mathematical analysis techniques, we establish new results to ensure that all solutions of the networks converge exponentially to zero point.     

Study on radiative heat transfer property of fiber assemblies using FTIR

Radiative heat transfer could be a significant contribution to the total heat transfer within the highly porous materials. This article reports on the use of a conventional instrument, viz. Fourier transform infrared (FTIR) spectroscopy, for the characterization of radiative heat properties of fiber assemblies with low bulk densities. Experimental measurements on spectral transmission with FTIR were performed on five types of fiber assemblies commonly used for insulating materials. From the measurements, radiative heat conductivity was determined by calculating extinction coefficient using Beer’s Law and applying the diffusion approximation approach. Bulk density, fiber arrangement, and temperature influences to radiative heat transfer were discussed. Results show that radiative heat conductivity decreases with bulk density and that of the random arranged fiber assemblies shows lower radiative heat conductivity than the random ball and parallel arranged fiber assemblies. Radiative heat conductivity is proportional to the cubic temperature. The existing theoretical model was modified by comparing theoretical and experimental radiative heat conductivity results.     

A Discussion of the Effect of Tortuosity on the Capillary Imbibition in Porous Media

In the past decades, there was considerable controversy over the Lucas–Washburn (LW) equation widely applied in capillary imbibition kinetics. Many experimental results showed that the time exponent of the LW equation is less than 0.5. Based on the tortuous capillary model and fractal geometry, the effect of tortuosity on the capillary imbibition in wetting porous media is discussed in this article. The average height growth of wetting liquid in porous media driven by capillary force following the [`(L)] _s(t) ~ t^1/2D_T{\overline L _{\rm {s}}(t)\sim t^{1/{2D_{\rm {T}}}}} law is obtained (here D _T is the fractal dimension for tortuosity, which represents the heterogeneity of flow in porous media). The LW law turns out to be the special case when the straight capillary tube (D _T = 1) is assumed. The predictions by the present model for the time exponent for capillary imbibition in porous media are compared with available experimental data, and the present model can reproduce approximately the global trend of variation of the time exponent with porosity changing.