Two New Eremophilenolides from Ligularia muliensis

Many Ligularia species have long been used as traditional folk medicine for theirantibiotic, antiphlogistic and antitussive activities1, and were found to be an importantsource of eremophilane. In the course of our search for bioactive sesquiterpenoids, w…     

Controlled growth of calcium carbonate by poly(ethylenimine) at the air/water interface

Two metastable calcium carbonate polymorphs, hemispherical vaterite and needle-like aragonite, are selectively formed at the air/water interface by the mediation of poly(ethyleneimine)(with molecular weights of 25000 and 2000, respectively) dissolved in supersaturated calcium bicarbonate solution.     

表面涂覆CeO2对Co—40Cr合金氧化行为的影响

研究了表面涂覆ＣｅＯ２对Ｃｏ－４０Ｃｒ合金在１０００℃、空气中恒温氧化和循环氧化的影响。并用扫描电镜／能谱（ＳＥＭ／ＥＤＸＳ）、电子探针（ＥＰＭＡ）、高分辩率显微镜（ＨＲＥＭ）等测试手段对氧化膜的形貌和成分进行了观察了监测。结果表明，涂覆ＣｅＯ２后极大地提高了合金的抗循环氧化性能。研究表明，涂覆的ＣｅＯ２主要以细小颗粒 蒿度弥散存在于氧化膜的外表面，并且主要分布于氧化物晶界上，其中Ｃ     

Direct Electrochemistry of Cytochrome C on the Glassy Carbon Electrode Modified with 1-Pyrenebutyric Acid/MWNTs

With 1-Pymnebutyric acid （PBA） and multiwalled carbon nanotubes （MWNTs）, glassy carbon electrode modified was successfully prepared. In phosphate buffer solution （pH 7,0）, the direct electrochemistry of cytochrome C （Cyt C） was realized. In the cyclic voltammetry experiment two pairs of redox peaks ofCyt C were observed at 0.018 V and -0.314 V （vs. SCE）, respectively. The redox reaction at 0.018 V was diffusion controlled, while the redox reaction at -0.314 V was adsorption controlled.     

Furostanol saponins with inhibitory action against COX-2 production from Tupistra chinensis rhizomes

Two furostanol saponins were obtained from the n-butanol fraction of methanol extract from Tupistra chinensis rhizomes,a folk medicine of Shennongjia Forest District of Hubei Province.Their structures were determined as (25S)-26-O-(β-D-glucopyranosyl)- furost-1β,3β,22α,26-tetrol-3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside (1) and (25R)- 26-O-(β-D-glucopyranosyl)-furost-1β,3β22α,26-tetrol 3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→2)-β-D-glu- copyranoside (2),on basis of chemical and spectroscopic evidences.1 and 2 displayed marked inhibitory action towards COX-2 production in macrophages of the rat abdomen induced by LPS at 20μg/mL.     

Benzylation of Aromatic Compounds with Benzyl Chloride Catalyzed by Nafion/SiO_2 Nanocomposite Catalyst

Diphenylmethane and substituted diphenylmethane are important compounds forsynthesis chemistry as well as industrial chemistry. These compounds are easilysynthesized by the benzylation of aromatic compounds with benzyl chloride or benzylalcohol catalyzed by homogeneous acid catalysts, such as AlCl3, FeCl3, H2SO4, HF andBF3. However, these catalytic systems are highly corrosive, and usually proceed withlow selectivity. In addition, they are less satisfactory from the environmen…     

A Novel Synthesis of (-)-10-epi-α-Cyperone

The eudesmane derivative, (-)-10-epi-α-cyperone 1, is widely used as a chiral starting material for the synthesis of other fused-ring sesquiterpenes1. The first synthetic work was reported by Howe and co-workers via condensation of (+)-dihydrocarvone 2 with 1-diethylaminopentan-3-one methiodide in 32% yield2. Previously, our group reported the synthesis of compound 1 by treating ketone 2 with ethyl vinyl ketone (EVK) directly under different conditions1a, but the yields were not satisfacto…     

SYNTHESIS AND CHARACTERIZATION OF N-（1-NAPHTHYL） SUCCINIMIDE

In this paper a modified two-step procedure for synthesis of N-（1-naphthyl） suecinimide （NaS） was developed, and the molecular structure of NaS was properly characterized by XRD, FT-IR, 1H NMR, DSC, etc. The results show that the melting point of our product is 159 ℃-160.5 ℃, and the characteristic infrared absorption band of carbonyl group splits into two peaks （1705cm^-3/1779cm^-3）, which are found to be quite different from the documented data （rap 147℃ -149℃; IR C=0-1700cm^-3）. Besides, photophysical spectroscopy was found to be powerful to study the molecular structure and crystal morphology of NaS compound.     

基于模场自积增强检测的光纤声光旋转传感器

介绍了一种应变不敏感的基于模场自积增强检测的光纤声光旋转传感器.通过调节加载到光纤声致光栅上的微波频率能使双模光纤输出高纯度LP_(11)模式.采用自积增强算法显著提高传感分辨比例,改善探测速度,实现对环境旋转角度变化的动态监测.传感器在0°—180°的测量范围内,角度最大测量误差范围小于11%;在轴向应变为100—1500με之间对应变不敏感.