壳聚糖不饱和羧酸盐聚集行为的研究

以半干法制备了一系列壳聚糖不饱和羧酸盐--壳聚糖水杨酸盐(a1)、壳聚糖苯甲酸盐(a2)、壳聚糖肉桂酸盐(a3)壳聚糖丙烯酸盐(a4)和壳聚糖衣康酸盐(a5).用红外光谱和紫外光谱表征了该产品的结构,以凯氏定氮法测定了羧酸的结合量.结果表明壳聚糖和不饱和羧酸盐是通过壳聚糖上的氨基和羧酸中的羧基发生了成盐反应,羧酸的结合...     

求解渗流自由面的复合单元全域迭代法

渗流自由面是岩体水力学研究的重点和难点,也是边坡稳定性综合研究的重要内容.基于对渗流自由面数值求解方法的分析,提出了复合单元全域迭代法,并编制了有限元计算程序.计算果表明,该法具有程序处理比较简单、计算结果比较精确等特性,一般迭代5次左右便可收敛.     

2-(p-十二烷氧基苯乙炔基)吡嗪-5-羧酸的合成及成膜性

在含有吡嗪环的对位双环羧酸化合物中,2-(p-十二烷氧基苯基)吡嗪-5-羧酸具有良好的成膜性^[1,2].在苯环和吡嗪环间引入不饱和键,合成的2-(p-十二烷氧基苯乙炔基)吡嗪-5-羧酸,由于其具有较长的共轭体系,因而分子排列的取向性更好,形成的LB膜更致密.该化合物尚未见报道.本文报道该化合物的合成方法及成膜的初步结果.     

不饱和聚酯树脂的减收缩作用(Ⅰ)——几种常用高分子的减收缩作用

不饱和聚酯树脂(简称UP-树脂)固化时体积收缩率高达7％～10％,限制了它的应用范围,七十年代以来,国外已开始生产低收缩不饱和聚酯树脂,并有不少这方面的专利,我国尚未见有关研究低收缩树脂的报道,我们考察了PS、PE、PVC、330聚醚及醇酸树脂的减收缩效果并用于191 UP-树脂,制成了无填料浇铸板及散状模塑料,测定了它们的体积收缩率、线收缩率以及力学和热学性能,发现PS、PE、PVC及330聚醚只宜做散状模塑料,而醇酸树脂则既可做散状模塑料又可做无填料浇铸板,性能均较好。     

王营子矿煤层中水—煤层气两相流体渗流规律的研究

本文通过在实验室中自行设计的装置,测定了阜新王营子矿煤层中水、煤层气共同流动时的两相流体的流量、渗透率及随水的饱合度变化关系,并根据这种数据模拟出了该煤层反映水、煤层气渗透基本规律的数学关系式,从而为它的煤层气开采提供了理论依据。     

A micro-investigation on water bridge effects for unsaturated granular materials with constant water content by discrete element method

The most common state of surface soil is unsaturated. Changes in water content will substantially impact its strength, leading to geological and engineering catastrophes. This paper used LIGGGHTS software to simulate the water bridge effect of unsaturated granular materials with constant water content and verify the rationality of the simplification of the stress-force-fabric (SFF) relationship. The results showed that the capillary force was not isotropic, which was different from the previous study, thus it cannot be overlooked in the simplification of the SFF relationship. Moreover, the influence of water content on the macroscopic mechanical behavior of unsaturated granular materials was interpreted through the evolutions of coordination number, interparticle force, fabric and force anisotropy, and other microscopic parameters. Compared to the literature, we found that different water bridge models would not change the characteristics of the solid skeleton.     

求解带自由面渗流问题移动网格法的改进及其工程应用

采用有限元固定网格和移动网格相结合的方法,求解带自由面的坝体稳定渗流问题。本方法是针对一般坝体的结构,在有限元网格生成之后,又自动生成了网格移动所需的信息,实现了网格在迭代计算中随自由面的变化自动均匀移动;讨论了网格奇异的不同类型,提出了避免单元形状怪异的移动网格方法;在欧拉空间中分区记录坝体不同的渗透性能,在网格移动到新位置后,自动识别网格所在的物性空间,从而确定单元在新位置上的渗流系数。本文将该方法应用到吉林丰满混凝土重力坝防渗加固的实际工程当中,在考虑大坝原有防渗措施的前提下,利用数值分析,研究了防渗芯墙对大坝渗流性能的影响。计算结果表明,加芯墙后坝体自由面位置明显下移,湿水部分大为减少,坝基扬压力没有明显提升,下游出水点位置没有明显下降。计算过程表明,本文方法及措施具有很好的收敛性与稳定性,且收敛性与自由面初始位置的选择无关。     

Copper-Catalyzed Asymmetric Acylboration of 1,3-Butadienylboronate with Acyl Fluorides

We report herein a Cu-catalyzed regio-, diastereo- and enantioselective acylboration of 1,3-butadienylboronate with acyl fluorides. Under the developed conditions, the reactions provide (Z)-β,γ-unsaturated ketones bearing an α-tertiary stereocenter with high Z-selectivity and excellent enantioselectivities. While direct access to highly enantioenriched E-isomers was not successful, we showed that such molecules can be synthesized with excellent E-selectivity and optical purities via Pd-catalyzed alkene isomerization from the corresponding Z-isomers. The orthogonal chemical reactivities of the functional groups embedded in the ketone products allow for diverse chemoselective transformations, which provides a valuable platform for further derivatization.     

Single-Nitrogen Atom Incorporation into B=B Bond via the N=N Bond Splitting of Diazo Compound and Diazirine

Triboraazabutenyne 3 is synthesized by the reaction of diboraazabutenyne 1 with aryl boron dibromide followed by the reduction. The ligand exchange to replace phosphine on the terminal sp² B atom with carbene furnishes 4 . ¹¹B NMR, solid-state structures, and computational studies disclose that 3 and 4 feature the extremely polarized B=B bond. 4 readily splits the N=N bond of both diazo compound and diazirine under ambient conditions, whereby one nitrogen atom is incorporated into the B=B moiety leading to a neutral diboraazaallene 6 . The mechanism of the reaction between 4 and diazo compound is extensively investigated by density functional theory (DFT) calculations, as well as the isolation of an intermediate.