水煤浆添加剂与煤之间的相互作用规律研究 Ⅰ. 复合煤颗粒间的相互作用对水煤浆流变性的影响

使用12种不同分散剂对14种不同变质程度的煤进行了成浆性实验，分析了182个水煤浆(CWS)样品的流变性。结果表明，低变质程度和高灰煤浆多呈屈服假塑性，煤的性质起主导作用；变质程度高且灰分较低煤浆的流变性，主要依赖于分散剂的结构与性质；分子结构单元立体空间效应大，疏水基团与亲水基团呈立体间隔分布的分散剂，易形成屈服假塑性CWS；分子线度长，亲水基团与疏水基团呈线性间隔分布的分散剂，易形成胀塑性CWS。复合煤粒间的相互作用方式是决定CWS流变特性的关键。     

1,2-丁二醇共聚对聚对苯二甲酸乙二醇酯结晶行为及力学性能的影响

为了探索生物基乙二醇中的1,2-丁二醇(1,2-BDO)作为共聚单体对生物基聚对苯二甲酸乙二醇酯(PET)的结晶行为和力学性能的影响。 本文合成了生物基PET均聚物和不同1,2-BDO共聚单元摩尔分数的系列生物基PET共聚物(共聚单体摩尔分数分别为2.0%、2.7%和5.6%),并采用傅里叶变换红外光谱仪(FTIR)、差示扫描量热仪(DSC)和力学测试等技术手段研究了其结晶行为和力学性能。 结果表明,随着1,2-BDO共聚单元摩尔分数的增加,PET共聚物的熔融温度、结晶速率及结晶度均明显降低,表明1,2-BDO共聚单体的引入破坏了PET分子链的规整性,阻碍了PET链段的结晶。 PET材料的拉伸强度随着1,2-BDO共聚单元摩尔分数的增加而降低,而弯曲强度和弯曲模量略有升高。     

压力流驱动电色谱分析方法及其若干色谱行为

压力流驱动电色谱分析方法是一种新型色谱技术。它组合了ＨＰＬＣ和电泳两种技术，为分离提供了更多可控制的因素。介绍了压力流驱动电色谱的装置和毛细管电色谱柱的装置方法，从理论上讨论了影响电色谱分离的因素并用实验数据加以证明。最后尝试性地将电色谱法用于测定香蕉样品中萨索啉（Ｓａｌｓｏｌｉｎｏｌ）等的含量。     

Determination of methylated dibenzothiophenes in environmental sarnples by on-line HPLC-CGC

Concurrent solvent evaporation with a loop-type interface was used for on-line HPLC-CGC in the analysis of methylated dibenzothiophene (DBT) isomers in oil samples. The chromatographic behavior of 20 methyl DBT's was studied by HPLC on an aminopropylsilane DBTA phase and by GC on a selective methyl-phenylsilicone phase. That provided a method for analyzing by GC-flame photometric detection, the individual components of the DBT family, previously picked out of the crude oil matrix by HPLC. The GC oven temperature was shown to be critical during HPLC eluent introduction into the GC pre-column. Too high a temperature induced a severe broadening of early eluted peaks whereas a temperature too close to the boiling point of the liquid at the inlet pressure induced double peaks. Optimized conditions were retained on this basis and may be used for the analysis of other families of polyaromatic hydrocarbons.     

苯并噁嗪中间体/蛭石插层纳米复合物热固化行为的研究

通过对双酚A型苯并嗪中间体 (BOZ A) 蛭石插层纳米复合物固化过程的分析表明长链烷基铵阳离子对BOZ A的热开环聚合反应没有表现出催化作用 ,也不影响纳米复合物的结构形态 .不同蛭石含量的插层纳米复合物 ,在形成不同纳米分散状态的纳米复合物的过程中 ,蛭石晶片对BOZ A的热开环聚合具有明显不同的阻碍作用 ,蛭石含量为 3%的插层纳米复合物 16 0℃的凝胶化时间较纯树脂延长约 7min ,活化能升高约8kJ mol,固化反应热焓降低约 14J g ,使得固化物的固化程度较纯树脂降低约 7%～ 10 % ,阻碍作用最大 ,其它含量的次之     

Morphology, crystallization behavior and properties of impact-modified polypropylene copolymer with or without sodium benzoate as a nucleating agent

 The morphology, crystallization behavior, and properties of an impact-modified polypropylene (PP) copolymer with or without sodium benzoate were investigated. The contents of ethylene–propylene rubber (EPR) in the reactor-made PP copolymer is about 15 wt%. For comparison, blends of PP and EPR containing the same EPR composition were prepared by melt-mixing. Morphological studies by scanning probe microscopy indicated that the impact-modified copolymer consists of three different phases, i.e., polyethylene, PP, and EPR phases, which is considerably different from the morphology of the conventional PP/EPR blend of the corresponding composition. The impact-modified PP copolymer exhibited a higher crystallization rate in terms of the lower crystallization half-time and thus higher thermal and mechanical properties, such as impact strength and hardness, than the PP/EPR blend did. The addition of sodium benzoate as a nucleating agent to the copolymer increased the crystallization rate and the mechanical properties. Received: 4 June 2001 Accepted: 31 October 2001     

Qualitative properties of pulsating fronts for reaction–advection–diffusion equations in periodic excitable media

In this paper, we study the pulsating fronts of reaction–advection-diffusion equations with two types of nonlinear term in periodic excitable media. Firstly, for the case with combustion nonlinearity, the unique front is proved to decay exponentially when it approaches the unstable limiting state. Secondly, for the degenerate monostable type nonlinearity, it is shown that the front with critical speed is unique, monotone and decays exponentially at negative end, while the fronts of noncritical speeds decay to zero non-exponentially.     

Some Properties of Solutions to the Novikov Equation with Weak Dissipation Terms

In this paper, we investigate the Novikov equation with weak dissipation terms. First, we give the local well-posedness and the blow-up scenario. Then, we discuss the global existence of the solutions under certain conditions. After that, on condition that the compactly supported initial data keeps its sign, we prove the infinite propagation speed of our solutions, and establish the large time behavior. Finally, we also elaborate the persistence property of our solutions in weighted Sobolev space.     

Self-avoiding walks and trees in spread-out lattices

LetG _R be the graph obtained by joining all sites ofZ ^d which are separated by a distance of at mostR. Let (G _R ) denote the connective constant for counting the self-avoiding walks in this graph. Let (G _R ) denote the coprresponding constant for counting the trees embedded inG _R . Then asR, (G _R ) is asymptotic to the coordination numberk _R ofG _R , while (G _R ) is asymptotic toek _R. However, ifd is 1 or 2, then (G _R )-k _R diverges to –.Dedicated to Oliver Penrose on this occasion of his 65th birthday.     

Retrieval and chaos in extremely dilutedQ-Ising neural networks

Using a probabilistic approach, the deterministic and the stochastic parallel dynamics of aQ-Ising neural network are studied at finiteQ and in the limitQ. Exact evolution equations are presented for the first time-step. These formulas constitute recursion relations for the parallel dynamics of the extremely diluted asymmetric versions of these networks. An explicit analysis of the retrieval properties is carried out in terms of the gain parameter, the loading capacity, and the temperature. The results for theQ network are compared with those for theQ=3 andQ=4 models. Possible chaotic microscopic behavior is studied using the time evolution of the distance between two network configurations. For arbitrary finiteQ the retrieval regime is always chaotic. In the limitQ the network exhibits a dynamical transition toward chaos.