Improved cell morphology and reduced shrinkage ratio of ETPU beads by reactive blending

Thermoplastic polyurethane foam beads (ETPU) have attracted attention of researchers in recent years due to their wide use in industrial applications. In this study, a small amount of acrylonitrile-butadiene-styrene copolymer (ABS) was blended with TPU under the assistance of dicumyl peroxide (DCP) and maleic anhydride (MAH) to improve the cell morphology and reduce shrinkage ratio of the resulting blends. These blends were then foamed to prepare TPU/ABS blends foam beads in an autoclave using supercritical CO₂ as the blowing agent at different temperatures and FTIR spectra, and rheological and foaming properties of the samples were evaluated. The melt viscosity, melt strength and elasticity of TPU/ABS were improved with the increase of the ABS content. These results were attributed to the grafting and heterogeneous nucleation points provided by the ABS. These enhanced properties were used to produce foams with better cell morphology and increased expansion ratio. Furthermore, the TPU/ABS blends foam beads showed lower shrinkage ratios with increasing ABS content. Thus, the addition of ABS is a facile method for improving the cell morphology and anti-shrinkage properties of ETPU.     

有序Au/Ag纳米碗阵列的简易制备及其表面增强拉曼散射性能

通过湿法化学合成基于SiO₂胶体晶体的大面积有序Au/Ag纳米碗(Au/AgNB)阵列。首先,在玻璃基板上以3D SiO₂胶体晶体作为模板。然后,在Au纳米颗粒(AuNP)种子的帮助下,通过原位生长方法在模板上沉积一层Au纳米壳(AuNS)。再通过HCHO还原Ag⁺使AuNS表面进一步沉积Ag纳米壳,形成Ag/Au双纳米壳(Ag/AuNS)阵列。通过丙烯酸酯改性双向取向聚丙烯(BOPP)方便地获得了单层有序反转Ag/AuNB阵列。这种有序Au/AgNB阵列具有更佳的表面增强拉曼散射(SERS)活性,其SERS分析增强因子(AEF)可达2.23×10⁷。     

TITAN: A Code for Modeling and Generating Electric Fields—Features and Applications to Enzymatic Reactivity

We present here a versatile computational code named “elecTric fIeld generaTion And maNipulation (TITAN),” capable of generating various types of external electric fields, as well as quantifying the local (or intrinsic) electric fields present in proteins and other biological systems according to Coulomb's Law. The generated electric fields can be coupled with quantum mechanics (QM), molecular mechanics (MM), QM/MM, and molecular dynamics calculations in most available software packages. The capabilities of the TITAN code are illustrated throughout the text with the help of examples. We end by presenting an application, in which the effects of the local electric field on the hydrogen transfer reaction in cytochrome P450 OleT_JE enzyme and the modifications induced by the application of an oriented external electric field are examined. We find that the protein matrix in P450 OleT_JE acts as a moderate catalyst and that orienting an external electric field along the Fe─O bond of compound I has the biggest impact on the reaction barrier. The induced catalysis/inhibition correlates with the calculated spin density on the O-atom. © 2019 Wiley Periodicals, Inc.     

Smart nanoprobe based on two-photon sensitized terbium-carbon dots for dual-mode fluorescence thermometer and antibacterial

Accurate temperature measurement plays an important role in a variety of industrial processes and scientific researches. In our work, the dual-mode temperature response nanoprobe CDs-Tb-TMPDPA containing a two-photon ligand (4-(2,4,6-trimethoxyphenyl)-pyridine-2,6-dicarboxylic acid, TMPDPA) sensitized Tb³⁺ as a temperature-sensitive unit and carbon dots (CDs) as photothermal reagent and a fluorescence reference unit, have been designed and synthesized. In this system, both the fluorescence intensity ratio and the fluorescence lifetime have a good response to temperature. In addition, due to the excellent photothermal conversion capability of CDs, photothermal antibacterial ability was also tested. Based on the temperature dependence of the fluorescence and the two-photon excitation characteristics of CDs-Tb-TMPDPA, the nanoprobe can also be used in the anti-counterfeiting. Our finding opens a new prospect for the use of two-photon sensitized dual-mode fluorescence thermometers.     

非紧完备的Khler流形上的嵌入问题

本文证明了任一n维的非紧完备,具有有限拓扑型的Kahler流形,若它的Ricci曲率为正的,有限的且陈氏示性数有限,则它双全纯等价于拟射影代数簇.     

我国社会诚信建设的博弈分析

社会诚信体系是建设社会主义市场经济的必要条件也是构建社会主义和谐社会的根本要求.社会诚信体系由个人诚信体系、企业诚信体系和政府诚信体系构成,利用博弈分析方法,分析个人诚信、企业诚信和政府诚信间的博弈问题,根据博弈结果提出我国社会诚信建设的相应对策.     

Large families of pseudo-random subsets formed by generalized cyclotomic classes

Recently, Dartyge and Sárközy defined the measures, i.e., the well- distribution measure and the correlation measure of order k, of pseudo-randomness of subsets of the set {1, 2, . . . , N}, and they presented several examples for subsets with strong pseudo-random properties when N is a prime number. In this article, we present a construction of pseudo-random subsets for N = pq and give some partial results on the pseudo-random measures.     

关于三幂等矩阵的秩特征的研究

本文对已有的关于三幂等矩阵秩的等式作了进一步研究，指出其中有些可以作为判定三幂等矩阵的充要条件，即三幂等矩阵的秩特征等式，本文还证明了有无穷多种三幂等矩阵的秩特征等式形式．     

Electrochemiluminescent Detection Method for Glyphosate in Soybean on Carbon Fiber-ionic Liquid Paste Electrode

A carbon fiber paste electrode using ionic liquid as the binder (CFILE) was fabricated. The electrochemical characteristics of the electrode was examined in ferro‐/ferricyanide solution and showed better conductivity and reversibility when compared with graphite paste‐ionic liquid electrode (GPILE) and a little better than that on the carbon nanotube paste‐ionic liquid electrode (CNTILE). Glyphosate (GLY), a pesticide, exhibited excellent catalysis to the oxidation of Ru(bpy)²⁺₃ on CFILE and brought an obvious enhancement to the electrochemiluminescence (ECL) intensity of Ru(bpy)²⁺₃. Based on the catalytic ability of GLY, a simple ECL method for GLY detection had been established. Under optimum conditions, the enhanced ECL intensities were found to had linearly respond to the GLY concentration between 3.0×10^?7 and 3.0×10^?5 mol/L, and the detection limit (S/N=3) was 2.0×10^?7 mol/L. The electrode also showed excellent sensitivity in detecting GLY‐spiked soybean samples. The linear range for GLY in soybean samples was 1.0×10^?6–4.0×10^?5 mol/L and the detection limit was 5.0×10^?7 mol/L, equal to 8.45 µg GLY in per gram of soybean. The detection limit in soybean sample was lower than the USA, EU regulation and so on. If the method is coupled with the separation technology, it can be applied to detect the GLY in the contaminated samples.