The effect of the curing agent content on the curing and liquid‐crystalline phase of liquid‐crystalline epoxy resin

The effect of the curing agent content on the curing behavior and liquid‐crystalline (LC) phase of the liquid‐crystalline epoxy (LCE) resin 4,4′‐di(2,3‐epoxypropyloxy)phenyl benzoate was studied. Diaminodiphenylester (DDE) was used as a curing agent. The curing behavior was observed via differential scanning calorimetry, and the LC phase was investigated with a polarized optical microscopy. The LC phase in the LCE/DDE mixture with a high DDE content was developed during curing. The onset time was inversely proportional to the DDE content. The mesophase stability of LCE/DDE was enhanced by the addition of large amounts of DDE. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 374–379, 2001     

香豆素基Schiff碱类化合物的合成及抗氧化性能

以2,3,4-三甲氧基苯甲醛为原料,经脱甲基、Knoevenagel缩合、亲核加成等反应合成了2个香豆素基Schiff碱类化合物,其结构经核磁共振谱(¹H NMR))和质谱(MS)确证。 并采用淬灭二苯代苦味肼基自由基(DPPH)、2,2'-联氮双(3-乙基苯并噻唑啉-6-磺酸)二铵盐(ABTS)和羟自由基等方法对其体外抗氧化性能进行了表征。 结果表明,目标化合物对3种自由基均具有一定的淬灭活性,其中对DPPH和羟自由基的淬灭活性高于母体化合物7,8-二甲氧基-3-氨基香豆素,具有较高的抗氧化活性。     

A Dual Colorimetric and Fluorometric Sensor for Lead Ion Based on Conjugated Polydiacetylenes

A PDA based sensor, derived from a di‐(2‐picolyl) amine (DPA) substituted diacetylene monomer, displayed a selective colorimetric change and a large fluorescence enhancement in the presence of lead ions. The lead selective PDA‐based chemosensor enabled easy detection of the presence of lead in 100% aqueous solution by the naked‐eye.

     

Synthesis of the Anti‐HIV Agent (−)‐Hyperolactone C by Using Oxonium Ylide Formation–Rearrangement

Starting from readily available (S)‐styrene oxide an asymmetric synthesis is described of the naturally occurring anti‐HIV spirolactone (?)‐hyperolactone C, which possesses adjacent fully substituted stereocenters. The key step involves a stereocontrolled Rh^II‐catalysed oxonium ylide formation–[2,3] sigmatropic rearrangement of an α‐diazo‐β‐ketoester bearing allylic ether functionality. From the resulting furanone, an acid‐catalysed lactonisation and dehydrogenation gives the natural product.     

Four new isoflavonoids from the stem bark of Erythrina variegata

Bioassay-directed fractionation of the stem bark extract of Erythrina variegata L. has resulted in the isolation of three new isoflavones: 5,4'-dihydroxy-8-(3,3-dimethylallyl)-2'-methoxyisopropylfurano[4,5:6,7]isoflavone (1), 5,7,4'-trihydroxy-6-(3,3-dimethylallyloxiranylmethyl)isoflavone (2), 5,4'-dihydroxy-8-(3,3-dimethylallyl)-2'-hydroxymethyl-2'-methylpyrano[5,6:6,7]isoflavone (3) and a new isoflavanone, 5,4'-dihydroxy-2'-methoxy-8-(3,3-dimethylallyl)-2',2'-dimethylpyrano[5,6:6,7]isoflavanone (4) together with seven known compounds, euchrenone b10 (5), isoerysenegalensein E (6), wighteone (7), laburnetin (8), lupiwighteone (9), erythrodiol (10), and oleanolic acid (11). The structures were determined on the basis of spectroscopic analyses and chemical evidence. The effect of these compounds on the proliferation of rat osteogenic sarcoma (UMR106) is also reported.     

铜导线短路熔痕的XPS研究

利用氩离子溅射对熔痕样品进行了深度刻蚀,同时利用Cu的俄歇谱线和计算的俄歇参数值,对不同环境形成的铜导线短路痕迹的物相及元素分布规律进行了分析。根据刻蚀时间可将一次短路熔痕表面膜层分为三部分,即C含量迅速减少的近表面层;O含量变化不大,C含量逐渐消失且有Cu₂O相的中间层;无Cu₂O相,O含量显著减少的过渡层。而将二次短路熔痕表面膜层分为两部分：C含量迅速减少的近表面层;无Cu₂O相,C和O量逐渐减少层。由此可见,一次短路熔痕的表面膜层与基体分界明显,有显著的过渡层,而二次短路熔痕的表面膜层与基体分界不明显,无过渡层。综上所述,可以根据两种短路熔痕是否含有Cu₂O相以及定量分析结果来区分两种熔痕,为判断火灾原因提供新的技术依据。     

选择性富集分离虎杖中白藜芦醇苷的分子印迹聚合物的制备及分子识别性能研究

以白藜芦醇苷(POL)为模板分子,分别以丙烯酰胺(AM)、4-乙烯基吡啶(4-VP)、甲基丙烯酸羟乙酯(HEMA)、甲基丙烯酸(MAA)为功能单体,二甲基丙烯酸乙二醇酯(EGDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,采用本体聚合法制备白藜芦醇苷分子印迹聚合物。采用静态平衡结合实验研究了印迹聚合物对模板分子及不同底物的识别性能。结果表明,以丙烯酰胺为功能单体的印迹聚合物(MIP1)对模板分子的识别性能最好,其次是以4-VP为功能单体的聚合物(MIP2),以HEMA为功能单体的聚合物(MIP3)以及以MAA为功能单体的聚合物(MIP4)的分子识别性能较差。表明功能单体与模板分子之间相互作用的强弱对MIP的识别能力有较大的影响。静态平衡结合法以及Scatchard分析法表明,MIP1对模板分子呈现较好的结合能力和选择性,该印迹聚合物中形成了2类不同的结合位点,离解常数分别为7.43×10-5、3.70×10-3mol/L。将MIP1用于虎杖提取物中POL的固相萃取分离,效果良好。