三酰甘油氧化聚合物的制备型快速柱层析-体积排阻色谱测定法

建立了一种简便、灵敏、无需内标的检测油脂中三酰甘油氧化聚合物(TGP)的分析方法。以制备型快速层析柱(PFC)(flash硅胶柱,20 g,40～60μm,6 nm)分离1 g油脂样品中极性组分(PC),经高效体积排阻色谱(HPSEC)(GPC柱,Ф7.8 mm×300 mm,粒径5μm,孔径10 nm)将PC细分为氧化三酰甘油寡聚物(TGO)、氧化三酰甘油二聚物(TGD)、氧化三酰甘油单体(ox-TGM)、二酰甘油(DG)、游离脂肪酸(FFA)。结合重量法测定油脂中PC、面积归一法测定PC中TGP,可准确定量油脂中的TGP含量。结果表明,TGO、TGD分别在28～1 800、11～2 800 mg/L范围内线性关系良好,相关系数(r2)分别为0.998 2、0.998 7,TGO及TGD的检出限(LOD)分别为28、11 mg/L,定量下限(LOQ)分别为113、44 mg/L;相当于油脂中TGP的LOD为0.01%。PFC-HPSEC法检测油脂TGP的相对标准偏差(RSD)均小于10%。PFC对3个PC加标水平(2.27%、8.47%、30.94%)的平均回收率为95%～98%,相对标准偏差(RSD)均低于4%。PFC-HPSEC方法与经典的硅胶柱-HPSEC方法定量油脂TGP的结果吻合度高,相对误差为0～8.9%。该方法能够在2 h内实现各种油脂中TGP含量的定量检测,包括使用过的废弃油脂与未使用的食用油脂,尤其适用于低含量TGP的初榨油和精炼油脂。     

Direct Synthesis of Functionalized High‐Molecular‐Weight Polyethylene by Copolymerization of Ethylene with Polar Monomers

The introduction of even a small amount of polar functional groups into polyolefins could excise great control over important material properties. As the most direct and economic strategy, the transition‐metal‐catalyzed copolymerization of olefins with polar, functionalized monomers represents one of the biggest challenges in this field. The presence of polar monomers usually dramatically reduces the catalytic activity and copolymer molecular weight (to the level of thousands or even hundreds Da), rendering the copolymerization process and the copolymer materials far from ideal for industrial applications. In this contribution, we demonstrate that these obstacles can be addressed through rational catalyst design. Copolymers with highly linear microstructures, high melting temperatures, and very high molecular weights (close to or above 1 000 000 Da) were generated. The direct synthesis of polar functionalized high‐molecular‐weight polyethylene was thus achieved.     

Separation of three polar compounds from Rheum tanguticum by high‐speed countercurrent chromatography with an ethyl acetate/glacial acetic acid/water system

The separation of polar compounds by high‐speed countercurrent chromatography is still regarded as a challenge. In this study, an efficient strategy for the separation of three polar compounds from Rheum tanguticum has been successfully conducted by using high‐speed countercurrent chromatography. X‐5 macroporous resin chromatography was used for the fast enrichment of the target compounds. Then, the target fraction was directly introduced into high‐speed countercurrent chromatography for separation using ethyl acetate/glacial acetic acid/water (100:1:100, v/v/v) as the solvent system. Consequently, three polar compounds including gallic acid, catechin, and gallic acid 4‐O‐β‐d ‐(6′‐O‐galloyl) glucoside were obtained with purities higher than 98%. The results showed glacial acetic acid could be such an appropriate regulator for the ethyl acetate/water system. This study provides a reference for the separation of polar compounds from natural products by high‐speed countercurrent chromatography.     

Partitioning behaviour of organic compounds between ionic liquids and supercritical fluids

Applications and prospects of two-phase, tuneable solvent systems composed of ionic liquids (ILs) and supercritical fluids with an emphasis on supercritical carbon dioxide (scCO(2)) are reviewed. The IL-scCO(2) biphasic systems have increasingly been used in diverse fields of chemistry and technology, and some examples of these applications are mentioned here. Rational design of such applications can obviously benefit from pertinent data on phase equilibria including the partition coefficients of the prospective products and reactants between the two phases. Therefore, a reliable technique to measure the limiting partition coefficients would be of value. Here, the pros and cons of supercritical fluid chromatography in this respect are discussed. An overview of methods for predictive thermodynamic modelling of binary (IL-scCO(2)) and ternary (solute-IL-scCO(2)) systems is also included.     

XPS研究多壁碳纳米管的阳极氧化处理效果

采用阳极氧化法对多壁碳纳米管（MWNTs）进行表面处理以提高其表面极性官能团含量。研究了不同电解参数对MWNTs处理结果的影响，采用X射线光电子能谱对处理前后的MWNTs的表面特征进行了分析。结果表明，经阳极氧化处理后，MWNTs表面氧原子摩尔分数与极性官能团总量均有不同程度增加。通电量和碱性电解质的电导率（物质的量浓度）是阳极氧化处理过程的主要影响因素，MWNTs表面极性官能团总量的增加可以归结为羟基的增加和羰基的减少，另外还探讨了可能的氧化反应机理。     

改进的状态方程用于极性体系汽液平衡计算(Ⅰ)

本文改进了ＳＲＫ、Ｐ—Ｒ和ＶＤＷ三个状态方程中的混合规则，并引入极性因子概 念，从而对强极性二元体系汽液平衡的计算获得较好的结果．     

三角B\''{e}zier曲面和四边B\''{e}zier曲面之间的相互转化

B\'{e}zier曲面有两种不同的形式:三角B\'{e}zier曲面和四边B\'{e}zier曲面,它们有着不同的基底和不同的几何拓扑结构, 但是它们也有很多共同的性质,因此三角B\'{e}zier曲面和四边B\'{e}zier曲面之间的相互转化就成为CAGD 里一个重要研究课题.在本文中, 我们用函数复合的方法实现两者之间的相互转化.被复合的两个函数, 一个用Polar形式表示,另一个用常见的Bernstein基形式表示.     

Structural and physical properties of BiFeO3 thin films epitaxially grown on SrTiO3（001） and polar（111） surfaces

The influence of surface polarity on the structural properties of BiFeO3 （BFO） thin films is investigated. BFO thin films are epitaxially grown on SrTiO3 （STO） （100） and polar （111） surfaces by oxygen plasma-assisted molecular beam epitaxy. It is shown that the crystal structure, surface morphology, and defect states of BFO films grown on STO substrates with nonpolar （001） or polar （111） surfaces perform very differently. BFO/STO （001）is a fully strained tetragonal phase with orientation relationship （001）[100]BFOII（001）[100]STO, while BFO/STO （111） is a rhombohedral phase. BFO/STO （111） has rougher surface morphology and less defect states, which results in reduced leakage current and lower dielectric loss. Moreover, BFO films on both STO （001） and STO （111） are direct band oxides with similar band gaps of 2.65 eV and 2.67 eV, respectively.