(6aR,11aR)-3-羟基-4,9-二甲氧基紫檀烷分子的晶体结构

从多刺锦鸡儿 (豆科 )中分离得到一个紫檀烷型化合物— (6aR ,11aR) 3 羟基 4,9 二甲氧基紫檀烷 ,通过红外光谱、质谱、核磁共振氢谱、核磁共振碳谱、氢核 氢核相关谱、异核多量子相干谱和异核多键相干谱进行结构鉴定 .其单晶经X射线衍射测试表明 ,该化合物晶体属单斜晶系 ,空间群为P2 1 ,化学式为C1 7H1 6 O5,Mr =3 0 0 .3 0 .晶胞参数为 :a =6.4778(13 ) ,b =12 .63 1(3 ) ,c=8.83 68(18) ,β =95 .80 (3 ) o,V =719.3 (3 ) 3,Z =2 ,Dc=1.3 86Mg/m3,F(0 0 0 ) =3 16,μ =0 .10 2mm- 1 .结构由直接法解出 ,用全矩阵最小二乘法修正 ,最终偏离因子R =0 .0 3 3 2 ,wR =0 .0 862 .该分子由一个苯并吡喃环和苯并呋喃环组成 ,X射线衍射测试表明其绝对构型为顺式紫檀烷型     

Two new b-hydroxy amino acid-coupled secoiridoids from the flower buds of Lonicera japonica:Isolation,structure elucidation,semisynthesis,and biological activities

Two new b-hydroxy amino acid-coupled secoiridoids,named serinosecologanin(1) and threoninosecologanin(2),were isolated from an aqueous extract of the flower buds of Lonicera japonica.Their uncommon structures including absolute configurations were determined by spectroscopic data analysis,and confirmed by semisynthesis from the co-occurring secologanin(3) and secologanic acid(4).Compounds 1 and 2 exhibited resistant activity against b-glucosidase from almonds and hesperidinase from Aspergillus niger,they also showed activity against the release of glucuronidase in rat polymorphonuclear leukocytes induced by the platelet-activating factor with inhibition rates of(34.9 3.1)% and(53.6 2.6)%,respectively.     

3S-7-羟基蜂蜜曲霉素分子的晶体结构

从红树林内生真菌Xylariasp．2508中分离到一个新的蜂蜜曲霉素型化合物3S-7-羟基蜂蜜曲霉素,这是首次从海洋真菌中获得该类结构的化合物并测定其晶体结构．通过核磁共振谱、红外光谱、质谱进行结构鉴定．其单晶经X射线衍射测试表明,该化合物晶体属单斜晶系,空间群为P21,化学式为C10H12O5,Mr=212．20．晶胞参数为:a=10．8884(19)(A|。),b=7.2284(13)(A|。),c=13．398(2)(A|。),β=104．217(3)°,V=1022．2(3)(A|。)3,Z=4,Dc=1．379 mg／m3, F(000)=448,μ=0．112 mm-1．结构由直接法解出,用全矩阵最小二乘法修正,最终偏离因子R=0．0498,wR=0．101．该分子由一个苯并吡喃环组成．通过与文献中已知3R-7-羟基蜂蜜曲霉素的熔点及旋光度对照,确定其绝对构型为3S．其初步抑菌实验结果表叫,3S-7-羟批蜂蜜曲霉素菌在每纸片200μg的剂量下对金黄色葡萄球菌(Staphylococcus aureus)没有表现出抑菌活性．     

STUDIES ON THE ISOLATION PURIFICATION AND CHARACTERIZATION OF THE FUCOIDAN-GALACTOSAN SULFATE (FGS) FROM LAMINARIA JAPONICA

1INTRODUCTIONFGSanditsderivationpossessremarkablemedicinalvalues:antitumouseffect,antiviralactivity,immunomodulation,bloodfatregulation,andhypoglycemia.Studiesonthepolysaccharidefromlaminariajaponicastartedatthebeginningof20thcentury.Thoughalginicacidfromlaminariajaponicahasalreadybeenindustrialized[1],peopledonotknownclearlyaboutlaminarinandfucoidan[2]becauseofrestrictionintheisolationandpurificationmethods[3].Weusedenzymolysistechnique,modernchromatographymethods,andspectralanalysistos…     

Sample preparation for gas chromatographic determination of halogenated volatile organic compounds in environmental and biological samples

In this review, the wide spectrum of the techniques of isolation and/or preconcentration and final determination of halogenated volatile organic compounds (HVOCs) in water, air, soil, sediment and biological fluids are presented and discussed. The techniques discussed are solvent microextraction, solid phase extraction, gas extraction (static and dynamic techniques), membrane processes and passive sampling. Also, direct techniques, such as direct aqueous injection into gas chromatography (GC) column and membrane inlet mass spectrometry, are presented. Main attention is paid to the practical application of these techniques during all HVOCs determination.     

Green analytical chemistry in sample preparation for determination of trace organic pollutants

The principles of green chemistry are applied to not only chemical engineering and synthesis, but also increasingly analytical chemistry. We describe environment-friendly analytical techniques applied to isolate and to enrich trace organic pollutants from solid and aqueous samples. Amounts of organic solvents used in analytical laboratories are reduced by applying solventless extraction, extraction using other types of solvent, assisted solvent extraction and miniaturized analytical systems.     

裙带菜中聚甘露糖醛酸的分离纯化与结构分析

以裙带菜(Undaria pinnatifida, wakame)为原料, 经水提醇沉、DEAE-Sepharose Fast Flow、Sephacryl S-300和Sephacryl S-200凝胶柱分离纯化, 得到2个酸性多糖UPPS03和UPPS04. 高效凝胶渗透色谱测试结果表明, 其为均一多糖, 平均分子量分别为3.6×104和1.1×104. 采用糖组成分析、高碘酸氧化及Smith降解、糖醛酸还原、甲基化、红外光谱和核磁共振等方法对该多糖的化学结构进行了表征. 结果表明, 2个多糖均为1,4连接的聚甘露糖醛酸.     

Capacitive micromachined ultrasonic transducers (CMUTs) with isolation posts

In this paper, an improved design of a capacitive micromachined ultrasonic transducer (CMUT) is presented. The design improvement aims to address the reliability issues of a CMUT and to extend the device operation beyond the contact (collapse) voltage. The major design novelty is the isolation posts in the vacuum cavities of the CMUT cells instead of full-coverage insulation layers in conventional CMUTs. This eliminates the contact voltage drifting due to charging caused by the insulation layer, and enables repeatable CMUT operation in the post-contact regime. Ultrasonic tests of the CMUTs with isolation posts (PostCMUTs) in air (electrical input impedance and capacitance vs. bias voltage) and immersion (transmission and reception) indicate acoustic performance similar to that obtained from conventional CMUTs while no undesired side effects of this new design is observed.     

具常数输入及饱和发生率的脉冲接种SIQRS传染病模型

研究了具有常数输入及饱和发生率的脉冲接种SIQRS传染病模型,得到了疾病消除与否的阈值R_0=1.证明了当R_01时,系统存在全局渐近稳定的无病周期解;当R_01时,系统一致持久.