VDF/CTFE共聚物原子转移自由基反应法氢化制备VDF/TrFE/CTFE三元共聚物的研究

报道了一种用于偏氟乙烯-三氟氯乙烯共聚物(VDF/CTFE共聚物)制备偏氟乙烯/三氟乙烯/三氟氯乙烯共聚物(VDF/TrFE/CTFE共聚物)的新方法,该方法以CuCl与2′,2-Bpy的配合物为催化剂,N-甲基吡咯烷酮(NMP)为溶剂,异丙苯(丙酮、2,6-二叔丁基-4-甲基苯酚)为链转移剂,通过原子转移法在VDF/CTFE共聚物上产生自由基,进而利用自由基链转移反应将VDF/CTFE共聚物上部分Cl原子用H原子取代以制备VDF/TrFE/CTFE三元共聚物.对该体系的反应机理及其影响因素进行研究发现,随着实验温度的升高(80～140℃),反应时间的延长,氢化量增加,产物中TrFE含量增加;反应温度越高,初始反应速度越快,完全氢化时间越短;催化剂与氢化量的比例基本为1:1,通过控制催化剂的量可以定量控制氢化率;新的反应体系不会对产物的分子量产生大的影响.     

由对苯二甲酰胺二醇合成聚酯酰胺及其扩链反应的研究

以N,N′-二(2-羟乙基)对苯二甲酰胺与己二酸及丁二醇缩聚,合成了同时带有端羧基与端羟基的聚酯酰胺预聚体,研究了不同扩链剂的扩链反应,获得了特性黏度达1.05 dL/g的聚酯酰胺.对预聚体及扩链后聚合物进行了红外与核磁表征,研究了聚合物的结构,并对聚合物进行了DSC与TG分析.     

Structure factor of ferrofluids with chain aggregates: Theory and computer simulations

In this paper we present theoretical and simulation results on the structure factor of mono- and bidisperse ferrofluids with chain aggregates, both with and without an applied external magnetic field. Chain distribution is obtained by the density functional theory (DFT). The radial distribution function (RDF) is calculated directly on the basis of the chain distribution and Fourier transformed to calculate the structure factor. An extensive comparison of the theoretical predictions to the results of the molecular dynamics computer simulations is provided. The proposed combined approach allows to elucidate the connection between experimentally observed small angle neutron scattering (SANS) images and the ferrofluid microstructure.     

Bayesian inference for Pr (Y

《Applied Mathematical Modelling》2014,38(5-6):1698-1709

Learning AMP chain graphs and some marginal models thereof under faithfulness

This paper deals with chain graphs under the Andersson–Madigan–Perlman (AMP) interpretation. In particular, we present a constraint based algorithm for learning an AMP chain graph a given probability distribution is faithful to. Moreover, we show that the extension of Meek's conjecture to AMP chain graphs does not hold, which compromises the development of efficient and correct score + search learning algorithms under assumptions weaker than faithfulness.We also study the problem of how to represent the result of marginalizing out some nodes in an AMP CG. We introduce a new family of graphical models that solves this problem partially. We name this new family maximal covariance–concentration graphs because it includes both covariance and concentration graphs as subfamilies.     

SEMICRYSTALLINE AND SUPERLATTICE STRUCTURES IN BINARY MIXTURE OF LONG CHAIN n-ALKANES C194H390 AND C294H590

Binary mixtures of long chain n-alkanes from C₁₂₂H₂₄₆ to C₂₉₄H₅₉₀ have been found to form solid solutions despite their large chain length differences [Zeng and Ungar. Novel Layered Superstructures in Mixed Ultralong n-Alkanes. Phys. Rev. Lett. 2001, 86, 4875–4978]. In this article we describe a study of the binary mixture of C₁₉₄H₃₉₀+C₂₉₄H₅₉₀ (50:50 w/w) using small angle x-ray scattering. The molecular chain length difference between the two components is 100 C-atoms, the largest so far studied. In accordance with the findings on some other binary mixtures, two types of lamellar structures are found: the semicrystalline form (SCF) at high temperatures (>105°C) and the triple-layer superlattice at low temperatures (<95°C). The SCF consists of alternating crystalline and amorphous layers: C₁₉₄H₃₉₀ molecules are fully crystallized in the crystalline layer while C₂₉₄H₅₉₀ molecules traverse the crystalline layer and are only partially crystalline; their protruding tails, or cilia, constitute the amorphous layer. The superlattice is a periodic 1-D array of triple-layer units: the two outer layers in the unit contain a mixture of C₁₉₄H₃₉₀ and C₂₉₄H₅₉₀ while the surplus tails of C₂₉₄H₅₉₀ coalesce and interdigitate in the center and form the third, thinner crystalline layer. In the superlattice form, the unusual diffraction order dependence of the linewidth is interpreted in terms of a particular type of stacking faults.     

Ab initio polypeptide structure prediction

The biological activity of a polypeptide strongly depends on its 3D structure. Ab initio prediction of the native structure from the sequence of amino acids has long motivated the development of an optimum energy model such that interactions present in the native conformation are stronger than those present in nonnative conformations and of algorithms capable of finding the basin of lowest free energy among an astronomically large number of possible conformations. Despite recent progress in our understanding of the factors responsible for both polypeptide stability and formation, computer simulations of polypeptide models are still far from being practical software tools for biologists. In this work, state-of-the-art computer simulations aimed at ab initio structure prediction in aqueous solution are reviewed and their strengths and weaknesses are highlighted. Received: 23 June 1999 / Accepted: 20 September 1999 / Published online: 15 December 1999     

Ionothermal synthesis and crystal structures of metal phosphate chains

We have prepared isostructural aluminium and gallium phosphate chains by ionothermal reactions in 1-ethyl-3-methylimidazolium bromide and 1-ethylpyridinium bromide under a variety of conditions. The chains can be prepared as pure phases or along with three dimensional framework phases. The chains are favoured at shorter heating times and the crystallinity can be improved by addition of transition metal acetates and amines which are not included in the final structure. The chain can be prepared with or without the presence of hydrofluoric acid.     

企业绿色供应链管理实证研究

随着环境压力的增加及资源的限制,建设绿色环保型企业已成为我国企业发展面临的迫切任务之一。绿色供应链管理即是绿色环保型企业建设的战略指导。本文在阐述绿色供应链管理基本内容的基础上,通过实证研究,对企业绿色供应链管理实践进行了统计分析,以识别中国企业绿色供应链管理实施状况及薄弱环节,为企业开展绿色供应链管理提供参考。     

Constacyclic codes over finite local Frobenius non-chain rings with nilpotency index 3

The main results of this paper are in two directions. First, the family of finite local Frobenius non-chain rings of length 4 (hence of nilpotency index 3) is determined. As a by-product all finite local Frobenius non-chain rings with $p^4$ elements, (p a prime) are given. Second, the number and structure of γ-constacyclic codes over finite local Frobenius non-chain rings with nilpotency index 3, of length relatively prime to the characteristic of the residue field of the ring, are determined.