高富勒烯的提取,分离和分析

采用二硫化碳重结晶富勒烯混合物或二硫化碳二次抽提烟灰以提取高富勒烯（ｈｉｇｈｅｒｆｕｌｅｒｅｎｅｓ，Ｃｎ，ｎ＞７０）。产物经高效液相色谱分析，高富勒烯的含量从１％分别提高到４％和６％；经激光飞行时间质谱证明，产物中除含主要成分Ｃ６０和Ｃ７０以外，还含有Ｃ７６、Ｃ７８、Ｃ８２、Ｃ８４以及更高碳原子的富勒烯。     

Dielectric studies under high pressure on strongly polar liquid crystals exhibiting monolayer smectic A phase

Dielectric studies have been performed at elevated pressures on two compounds of a homologous series possessing a strongly polar terminal group and three phenyl rings in their molecular structure. This is the first high pressure dielectric study on such systems that exhibit a monolayer smectic A phase. Also notable is the fact that these compounds show a dual frequency response, a promising feature for fast liquid crystal display devices. The low frequency relaxation recorded in the nematic and smectic A phases is attributed to the reorientation of the molecules about the short axis. The temperature and pressure dependence of the relaxation frequency of this mode as well as the involved activation parameters are discussed. At a given relative temperature the relaxation frequency decreases as the pressure is increased. However, the parameter that characterizes the temperature dependences of the relaxation frequency, viz., the activation enthalpy, has a very weak dependence on pressure. In contrast, the activation volume shows a linear decrease with temperature.     

Quantitative determination of UV filters in sunscreen lotions using microemulsion electrokinetic chromatography

Microemulsion electrokinetic chromatography (MEEKC) has been applied to the separation of some UV filters (Eusolex 4360, Eusolex 6300, Eusolex OCR, Eusolex 2292, Eusolex 6007, Eusolex 9020, Eusolex HMS, Eusolex OS, and Eusolex 232) commonly used in sunscreen lotions. Use of a MEEKC buffer with a mixed surfactant system to stabilize the oil droplets and an organic modifier in the aqueous phase allowed separation of most of the selected analytes in a single run in a system fitted with a diode array detector recording three wavelengths (240 nm, 300 nm, and 380 nm) simultaneously. The microemulsion employed consisted of 2.25 g of SDS, 0.75 g of Brij 35, 6.6 g 1‐butanol, 0.8 g n‐octane, 17.5 g 2‐propanol, and 72.1 g of 10 mM borate buffer (pH 9.2). Detection limits from 0.65 to 6.0 μg/mL were obtained and the calibration plots were linear over at least one order of magnitude for all analytes. The developed method could be applied to the determination of UV filters in several sun protection products including lotions, milks, and oils. Comparison of the obtained data with those from an HPLC method described in the literature showed acceptable agreement.     

Cellulase Activity in Different Buffering Media During Waste Paper Hydrolysis by HPLC

The activity of cellulase has traditionally been described by pH and temperature; however, the buffering medium is also an important factor, Taking plain water as a reference medium, three kinds of buffer including KH₂PO₄/K₅HPO₄, citric acid/sodium citrate, and acetic acid/sodium acetate were adopted to survey their effects on the activity of cellulase. Chromatographic assays indicated that xylose, glucose, and cellobiose were the major products and that minor products such as cellotriose and cellotetraose were present in some cases. The activities of cellulase based on glucose production showed that the phosphate buffer acted as a deactivator for cellulase and each of the two organic acid buffers acted as activators for cellulase. The concentration of activation buffer should be high to reach a high cellulase activity; however, this effect would be compensated for by the product inhibition of cellulase. The highest activity obtained was 4.16 ± 0.08 (× 10^?3) IU mg^?1 for the citric acid/sodium citrate buffer under pH 4.80, 40 °C and an agitation speed of 150 rpm.     

Enhanced Acid/Base Catalysis in High Temperature Liquid Water

High temperature liquid water (HTLW), as an environmentally benign medium, has drawn increasing attention for organic chemical reactions and biomass conversion1-3. HTLW has a strong tendency to ionize and can act as an acid and/or base catalyst. In addition, HTLW can dissolve organic compounds to some extent allowing for a homogenous reaction within an aqueous phase. Extensive researches4-10 have been pursued on acid/base-catalysis reactions in HTLW without addition of acid or base. Howe…     

手性高效液相色谱法测定1—（6‘—甲氧基萘）乙醇不对称氢酯基化反应

在自制的硅基纤维素－三（３，５－二甲基苯基氨基甲酸酯）高效液相色谱手性固定相上（ＨＰＬＣ－ＣＳＰ），优化了１－（６＇－甲氧基萘）乙醇氢酯基化反应产物－萘普生甲酯手性分离的条件，测定了相应的一系列不对称氢酯基化反应产物的对映体过剩值（ｅ．ｅ．值）。结果表明，在ＣＤＭＰＣ－ＣＳＰ手性柱上用ＨＰＬＣ测定此类不对称催化反应的光学产率，评价催化剂体系的手性选择是一种非常理想的方法。     

高分辨等离子体质谱法直接测定高纯镓中的痕量元素

建立高分辨电感耦合等离子体质谱法(HR-ICP-MS)测定高纯镓样品中Be、Mg、A l、S i、Ti、V、Cr、Mn、Fe、Co、N i、Cu、Zn、Ge、As、Mo、Ag、Cd、In、Sb、Ba、Pb、B i等痕量元素的方法。样品用HNO3 HC l经微波消解后,试液直接进样用HR-ICP-MS法同时测定上述元素,在高分辨质谱测量模式下避免了大量的质谱干扰,详细地研究了HC l和高纯镓所产生的基体效应,以Sc、Rh、Tl作为内标元素校正了基体效应,讨论和确定了实验的最佳测定条件。结果表明,23种痕量元素的检出限在0.001~0.21μg/L之间;回收率在89.8%~111.6%之间,相对标准偏差(RSD)小于3.3%。     

使用疏水作用色谱研究蛋白质的构象变化

研究了高效疏水作用液相色谱中(HIC)色谱条件改变对蛋白质构象的影响。发现固定相配体的疏水性、温度及流动相中盐的阴离子、阳离子和pH值都影响蛋白质的构象。     

高效离子排斥色谱法测定饮料中的糖精钠

提出了一种用高效离子排斥色谱法测定饮料中糖精钠的新方法。以ＩｏｎＰａｃ ＩＣＥ－ＡＳ ６柱为分离柱，０．１０ ｍｍｏｌ／ＬＨ２ＳＯ４＋甲醇（９＋１）为淋洗液，２０２ｎｍ波长下紫外检测。在１－１００ｍｇ／Ｌ范围内，糖精钠的含量与峰面积呈 良好线性关系。检出限为０．６０ｎｇ，灵敏度优于以往采用离子交换色谱－电导检测法的结果。在实验条件下，饮料 中常见有机酸以及其它人工合成甜味剂等均不产生干扰。方法用于饮料中糖精钠的测定，加标回收率为９８％～ １０５％。此外还比较了电导检测、紫外检测和经化学抑制系统后紫外检测等三种检测方式对测定灵敏度的影响。     

Effects of polystyrene-encapsulated magnesium hydroxide on rheological and flame-retarding properties of HIPS composites

In this study, polystyrene (PS)-encapsulated magnesium hydroxide (Mg(OH)₂) was successfully prepared by in situ polymerization of styrene on the surface of Mg(OH)₂ in a high-speed mixer. A large amount of PS chemically bonded on Mg(OH)₂ surface was confirmed by means of FT-IR, TGA and SEM. A series of composites of high impact polystyrene (HIPS) were prepared by melt blending in a co-rotating twin-screw extruder. The effects of PS-encapsulated filler on the properties of HIPS composites were studied by SEM, rheology and combustion tests (horizontal burning tests and cone calorimetry). The dispersion and adhesion patterns of PS-encapsulated Mg(OH)₂ in HIPS matrix were investigated through FT-IR and SEM. The experimental results demonstrated that comparing to the composites containing untreated filler, the rheological and flame retardant properties of those containing PS-encapsulated filler were found to be significantly improved. This improvement is mostly attributed to a better dispersion of the encapsulated filler and a strong adhesion between the filler and matrix.