基于香气成分气相色谱-质谱指纹图谱的判别分析和相似度评价用于绿茶等级差异研究

该文以研究指纹图谱在绿茶等级判别方面应用的可行性为目的。以信阳毛尖茶为研究对象，以茶汤香气成分为研究目标，采用顶空固相微萃取与气相色谱-质谱联用技术，筛选其香气特征成分，建立不同等级信阳毛尖茶香气成分GC-MS指纹图谱。发现运用判别分析法可以对2个系列7个等级41个信阳毛尖茶样进行很好的等级区分；通过不同等级色谱指纹图谱的相似度计算发现，相似度与茶样等级之间具有较好的相关性，尤其是对于品质较好的茶样，这种相关性更好。表明运用判别分析法和相似度计算方法能够反映绿茶等级之间的差异性，且基于相似度评价的方法具有客观量化的特征。     

Application of structured lighting sensor for online measurement

On the background of increasing request for stringent quality improvement and rising productivity, requirements for online measurement systems are growing as well. Among all the measurement tools, the vision system is considered as the most appropriate tool to provide proper accuracy, high speed, low cost, and 100% online inspection. Structure lighting sensor is the most popular method used in vision system. In this paper, the theory of vision system based on structure lighting is introduced. The measurement application to the seamless steel tube is introduced particularly. Another typical application, the online measurement on car body using structure lighting, is also illustrated.     

直接法制备三乙氧基硅烷催化剂的研究进展

综述了直接法合成三乙氧基硅烷的研究进展,着重对直接法的反应机理和催化剂组分的筛选进行了分析讨论.同时介绍了以三乙氧基硅烷为原料,合成烯丙基三乙氧基硅烷、γ-(2,3-环氧丙氧)丙基三乙氧基硅烷、苯乙基三乙氧基硅烷、五乙氧基二硅烷等衍生物的工艺,提出了催化剂制备过程中存在的问题及研究方向.     

Isothermal crystallization kinetics of polypropylene/POSS composites

Polypropylene (PP)/octavinyl polyhedral oligomeric silsesquioxane (POSS) composites were prepared by two different processing methods: reactive blending and physical blending, and the crystallization behavior of PP and PP/POSS composites was studied by means of differential scanning calorimetry and polarized optical microscope. The results showed that the crystallization of PP in PP/POSS composites was strongly influenced by the different processing methods. POSS particles can act as effective nucleating agent, accelerating the crystallization of PP. The crystallization rate increased more dramatically for the reactive blending composite due to the stronger nucleating effect of PP grafted POSS. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1762–1772, 2008     

聚4-乙烯基吡啶/SiO~2纳米杂化材料负载茂钛催化剂的制备 及苯乙烯聚合

以聚4-乙烯基吡啶(PVP)为有机组分,正硅酸乙酯(TEOS)为无机组分,利用sol-gel方法制得PVP/SiO~2纳米杂化材料,以此为载体制备了杂化材料负载单茂钛催化剂。利用XPS和IR分析了载体与CpTiCl~3的结合方式,确认对苯乙烯聚合有两种活性中心,苯乙烯聚合结果表明在50℃左右间规度达到最大;在70℃,n(Al)/n(Ti)=1500时活性最高可达1.09×10^6gPS/(molTi·h),GPC结果表明产物分子量分布呈双峰分布。     

用溶致液晶模板合成与组装纳米材料*

总结了溶致液晶作模板合成与组装纳米材料的各种方法,特别分析了近来兴起的以溶致液晶为构建支架,以纳米粒子为构建单元制备无机/有机杂合体的特点,并对未来发展趋势作了展望.     

A novel vertical alignment technology for nematic liquid crystals based on electrostatic self‐assembled method

A novel vertical alignment film for nematic liquid crystals is reported based on electrostatic self‐assembly of alkyl sulfonic salts in aqueous solution. A series of self‐assembled films with different alkyl chain lengths were prepared and used as alignment films. It was revealed that only when the number of carbon atoms in the alkyl chain approaches 11 or larger, could the self‐assembled film induce vertical alignment of liquid crystals. We also found that the homeotropic alignment of liquid crystals was related to the surface roughness of self‐assembled films. In addition, this vertical alignment film showed good electro‐optical characteristics and excellent thermal stability.     

Facile synthesis of calcium carbonate with an absolutely pure crystal form using 1-butyl-3-methylimidazolium dodecyl sulfate as the modifier

Calcium carbonate (CaCO₃) nanocrystals with controllable polymorph and morphology have been successfully synthesized with the aid of an effective control agent, a halogen-free, low-cost ionic liquid surfactant, 1-butyl-3-methylimidazolium dodecylsulfate ([C₄mim][C₁₂SO₄]) in a supersaturated aqueous solution. For the first time, facile preparation of pure lens-like vaterite, sheet-like calcite, and peanut-like aragonite was all achieved in the [C₄mim][C₁₂SO₄] aqueous solution through changing the concentration, temperature, and initial pH value and adding magnesium ions. Washed by water and ethanol, all the aggregates were free of [C₄mim][C₁₂SO₄] and can be stable at least 1 month in air. The crystal form of the aggregates changed from pure calcite to pure vaterite at room temperature only through increasing [C₄mim][C₁₂SO₄] concentration. Formation of the ordered CaCO₃ structures is mainly ascribed to the aggregation of the primary nanoparticles whose formation mechanism is related to the change of supersaturation. This study can provide a facile and environment-friendly method to fabricate CaCO₃ crystal aggregates with various morphologies and polymorphs and can be used for large-scale industrial production and biomimetic synthesis.     

Fully aromatic macrocycle‐terminated polyimide: synthesis and cross‐linking

This study reported a method to prepare fully aromatic macrocycle‐terminated polyimides (MC‐PI). The macrocycle of aryl ether ketones was prepared from (4‐amino)phenylhydroquinone and a di‐fluoro monomer under pseudo high dilution condition. Novel aromatic fully MC‐PI oligomers were successfully prepared by the reaction of 2,3,3′,4′‐biphenyltetracarboxylic diandhydride with 2,5‐bis(4′‐aminophenoxy)‐biphenyl and sulfur‐containing macrocycle of aryl ether ketone. The MC‐PI oligomers were cross‐linkable in the heating, and the glass transition temperatures of the polyimides increased after thermally cured. The cross‐linking reaction of MC‐PI could form fully aromatic thermosetting polyimide by ring‐opening reaction. After cross‐linking, these polyimides showed higher glass transition temperatures and excellent thermal stability. Copyright © 2013 John Wiley & Sons, Ltd.