Characterization of oxidation progress by chemiluminescence: A study of polyethylene with pro-oxidant additives

Non-isothermal chemiluminescence measurements in nitrogen and isothermal measurements in oxygen were used for the evaluation of degradation in pre-oxidized polyethylene either pure or containing Mn-based pro-oxidant additives. The results were compared with infrared spectroscopy data. Chemiluminescence measurements of pure polyethylene and polyethylene with additive made it possible to calculate the set of rate constants, based on the Bolland-Gee oxidation scheme. The oxidation rate constants of polyethylene with additive were significantly higher, while the activation energy of the process appeared lower (65 kJ mol⁻¹), than those of pure polyethylene. The method provides an access to study oxidation processes during the induction period of oxidation when infrared spectroscopy cannot provide sufficient information.     

一个环硫乙烷中间体的合成

为了获得制备超高折光树脂的单体, 合成了一个能够有效制备环高折光树脂的硫乙烷中间体——(甲氧基羰基二硫化)-环硫乙烷. 该中间体可以和硫醇在温和的条件下生成环硫单体. 和二巯基甲烷反应能生成2,2’-(亚甲基双二硫化)-双环硫乙烷单体, 聚合后得到了折光指数和阿贝数高达nD/νD＝1.79/28的热固性光学树脂.     

The smallest Hosoya index in (<Emphasis Type="Italic">n</Emphasis>, <Emphasis Type="Italic">n</Emphasis> + 1)-graphs

A (n, n + 1)-graph G is a connected simple graph with n vertices and n + 1 edges. In this paper, we determine the lower bound for the Hosoya index in (n, n + 1)-graphs in terms of the order n, and characterize the (n, n + 1)-graph with the smallest Hosoya index.     

Kekulé structures of hexagonal chains—some unusual connections

It is known since 1977 that the number K of Kekulé structures of a hexagonal chain is equal to the topological Z-index of a pertinently constructed “caterpillar” tree. Based on this relation we now connect K with some of other, seemingly unrelated, concepts: continuants (from number theory) and matchings of the path–graph (further related to Fibonacci numbers). We also arrive at a tridiagonal determinantal expression for K.     

Fibronectin adsorption on gold, Ti-, and Ta-oxide investigated by QCM-D and RSA modelling

The adsorption of fibronectin on gold, Ti-, and Ta-oxide surfaces is investigated by means of the quartz crystal microbalance with dissipation (QCM-D) technique. The surface chemistry (gold, Ti-, and Ta-oxide) is found to influence the frequency shift observed during adsorption of the fibronectin layer with the magnitude being Delta f Au>Delta f Ti-oxide approximately Delta f Ta-oxide. Corresponding variations in the dissipation change normalised to frequency change (Delta D/Delta f) for the layer are observed. The QCM-D data are further analyzed by the random sequential adsorption (RSA) model, and adsorption rate parameter ka and footprint (a) determined, which supported the trend seen in the Delta f and Delta D/Delta f values. The value of ka found by the RSA modelling of the QCM-D resonance frequency data is found to match the ratio between the mass measured by QCM-D and the mass reported by optical techniques in literature. We conclude that comparison of the adsorption rate parameter (ka) obtained by RSA modelling of the QCM-D data with ka values obtained from RSA modelling of data obtained using optical techniques can be a route to determine the degree of hydration of the adsorbed protein layer.     

Silicone nanomicelle dyeing method on polyester fibre: Comparative evaluation of chemical properties,fastness properties,and DFT

Disperse Red 177(9a), Disperse Red 343(9b), Disperse Blue 165(9c), Disperse Blue 165.1(9d), Disperse Blue 366(9e), and Disperse Blue 148(9f) were examined in the solvent. During silicon nanomicelle dyeing, we employed 9(a–f) azo disperse dyes on polyester. On polyester fabric, dye 9(a–f) offers equal washing, light, and rubbing fastness in both the conventional and silicone nanomicelle techniques. The dye can now be transported directly into the fibre core without the use of auxiliary dyes owing to the reduction in the particle size of azo dyes, which is made possible by nanoemulsions superior dispersion. The levelling property of the dispersed dye is enhanced by the dyeing process. When both techniques are applied, the lightfastness properties of all dyes are improved. It provides a very good to outstanding protection factor for textile materials. These 9(a–f) azo disperse dyes have moderate to outstanding photostability, net electrophilicity index, and lightfastness.     

Comparative study of degree-based molecular descriptors of cyclodextrins through M-polynomial and NM-polynomial

Cyclodextrins are natural oligosaccharides used to increase the solubility of drugs. It has numerous applications in drug discovery, food storage and other fields. Loftsson et al. explained about applications of Cyclodextrins(CDs) in administrating the drugs through various ways. Jansook et al. has given insights into the structure, physicochemical properties and pharmaceutical applications of CDs. In the present work, cyclodextrin and its derivatives such as α, β, γ CDs are studied for which various degree and neighborhood degree-based topological indices are computed through M-polynomial and NM-polynomial respectively and the comparison of the indices for all three types of cyclodextrins are presented which are of great importance in QSPR/QSAR studies.     

二元无机物标准熵 So298的拓扑研究

为了预测二元无机物的标准熵,基于分子图的连接矩阵和离子参数gi、qi,提出了一种新的连接性指数mQ, mG及其逆指数mQ’, mG’。 qi、gi定义为：qi=(1.1+Zi1.1) /(1.7+ni), gi=(1.4+Zi) /(0.9+ri+ri-1),其中Zi 、ni和 ri分别代表离子i的电荷数、最外层主量子数和半径。从0Q, 0Q’, 1G,和1G’,利用多元线性回归分析方法和人工神经网络方法,可以构建优良的QSPR模型。对371个二元无机物,其多元线性模型及神经网络模型的相关系数、标准偏差和平均绝对偏差分别是：0.9905, 8.29 J.K-1.mol-1, 6.48 J. K-1.mol-1, 0.9960, 5.37 J.K-1.mol-1 和 3.90 J.K-1.mol-1。留一法交叉验证表明,其多元线性模型具有良好的稳定性。两个模型对187个未进入模型的二元无机物的标准熵的预测值和实验值之间的相关系数、标准偏差和平均绝对偏差分别是：0.9897, 8.64 J. K-1.mol-1, 6.84 J. K-1.mol-1, 0.9957, 5.63 J.K-1.mol-1, 和 4.18 J.K-1.mol-1。研究表明,本文方法在预测二元无机物标准熵时比文献方法更有效,两种模型均能较精确的预测二元无机物的标准熵,且神经网络模型的预测结果更精确。     

A Note on the Game Chromatic Index of Graphs

In this note we prove that the game chromatic index χ _g ^′(G) of a graph G of arboricity k is at most Δ + 3k − 1. This improves a bound obtained by Cai and Zhu [J. Graph Theory 36 (2001), 144–155] for k-degenerate graphs. Tomasz Bartnicki: Research of the first author is supported by a PhD grant from Polish Ministry of Science and Higher Education N201 2128 33. Received: November 1, 2006. Final version received: December 22, 2007.     

A two-step estimator of the extreme value index

In this paper, we build a two-step estimator , which satisfies , where is the well-known maximum likelihood estimator of the extreme value index. Since the two-step estimator can be calculated easily as a function of the observations, it is much simpler to use in practice. By properly choosing the first step estimator, such as the Pickands estimator, we can even get a shift and scale invariant estimator with the above property. The author thanks Laurens de Haan for motivating this work and giving helpful comments. The author also thanks two anonymous referees for their useful comments.