Synthesis of Oligosaccharides Designed to form Micelles,Corresponding to Structures Found in Ovarian Cyst Fluid

ABSTRACT

The syntheses of α-D-GlcpNAc-(1→4)-β-D-Galp-(1→4)-β-D-GlcNAc-(1→O)-(CH₂)₁₅CH₃ (1) and fragments thereof, corresponding to structures found in human ovarian cyst fluid, are described. Silver triflate promoted coupling of 3,4,6-tri-O-acetyl-2-azido-2-deoxy-β-D-glucopyranosyl bromide (12) and galactose acceptor (11) gave a disaccharide donor (13), which was readily transformed into the corresponding bromo-derivative 18. For the synthesis of disaccharide β-D-Galp-(1→4)-D-GlcNAc, several differently protected glucosamine acceptors were prepared. It was found that cetyl alcohol needed to be introduced after the formation of the β-galactoside bond. Glycosylation of pent-4-enyl 3,6-di-O-benzyl-2-deoxy-2-tetrachlorophthalimido-β-D-glucopyranoside (30) with (3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-D-glucopyranosyl)-(1→4)-2,3,6-tri-O-benzoyl-α-D-galactopyranosyl bromide (18) by use of silver triflate as promoter gave the desired trisaccharide 31. Finally 31 was transformed via coupling to the long alkyl chain aglycon and deprotection into the title compound 1.     

Ab Initio Study of Structures,Metallotropic 1,2-Shifts and Prototropic 1,2-Shifts of Cyclopentadienyl(trimethyl)silane, -germane and -stannane

Molecular structures, metallotropic and prototropic shifts of cyclopentadienyl(trimethyl)silane ( 1 ), cyclopentadienyl(trimethyl)germane ( 2 ), and cyclopentadienyl(trimethyl)stannane ( 3 ) were investigated using ab initio molecular orbital and the Becke, Lee, Yang, and Parr density functional (B3LYP) methods. The results show that the most stable structure of compounds 1-3 has the (CH 3 ) 3 M fragment in the allylic position. The energy barrier of metallotropic shifts in compound 1 is higher than in 2 , and in compound 2 higher than in 3 , in good agreement with experimental data. The cyclopentadienyl rings in compounds 1-3 are found to be planar but this result contradicts the reported experimental data.     

红外光谱和逐步判别分析法应用于油菜籽的研究

用傅里叶变换红外光谱(FTIR)和逐步判别分析法对油菜籽的品种和产地进行鉴别研究。测试了来自5个产地17个油菜籽品种188份油菜籽皮样品的红外光谱,按产地和品种选择训练样本,每个品种选择5份为训练样本,剩下的作为测试样本,选择1 800～950 cm-1范围的光谱信息,在SPSS20.0的判别分析模块中采用逐步法,Fisher线性判别准则,分别建立油菜籽品种和产地的鉴别模型来判别样品的品种和产地;比较了逐步判别分析中五种筛选建模信息的算法所建立的模型对实验样品品种和产地的鉴别效果。基于油菜籽皮红外光谱信息的品种判别分析,五种筛选变量的算法所建立的模型都能较好的识别油菜籽的品种,“Wilks’ Lambda”法所建模型的识别效果最好,判别正确率为97.9%。基于油菜籽皮红外光谱信息的产地判别分析,五种筛选变量的算法所建立的产地判别模型也都能较好的识别油菜籽的产地,“Unexplained variance”法所建模型的识别效果最好,判别正确率为98.4%。研究结果表明,基于油菜籽皮中红外光谱信息的品种和产地判别分析,有望成为油菜籽品种和产地鉴别的方法。     

1，3-二甲基尿嘧啶二聚体的飞行时间质谱裂解规律研究

采用不同进样方式、不同电子轰击能量和不同反应气压力测定了1,3 二甲基尿嘧啶二聚体(DMUD) 的4个立体异构体A、B、C、D的化学电离(CI)和电子轰击电离(EI)飞行时间质谱.不同方式所测得的CI谱结 果一致,4个异构体出现了强度不同的准分子离子峰(m/z=281),由此推断它们结构之间的相对稳定性次序为: B(trans syn)>D(cis syn)>A(trans anti)>C(cis anti).这一结论被低能量(25eV)电子轰击的EI谱所证实, 并且与合成产物的比例相吻合.EI谱用任何方式测谱均不出现分子离子峰(m/z=280),而出现其单体离子(m/z =140)且为基峰。给出了DMUD的飞行时间质谱裂解途径,同时对CI谱的裂解碎片进行了细致的讨论.     

不同部位人体气味的分析研究

运用SPME-GC/MS法对同一个体腋窝部、手部和足部的人体气味样品进行了采样分析,通过比较3个部位人体气味样品色谱图中共有成分相对峰面积比和非共有成分,结合使用相似度法对3个部位的人体气味进行了比较分析,三者具有较高的相似度,但仍存在一些细微的差别。     

Parameter study of electrospinning of polyamide-6

Importance of different solution and process parameters were evaluated in multi-nozzle electrospinning of polyamide-6. We were interested in how those parameters affect firstly on fibre diameters and fibre diameter distribution and secondly on production rate and disturbances of the process. The trial series was planned using orthogonal experimental design. Altogether eight parameters having three or two levels each were chosen for this study. The chosen solution parameters were polymer grade, viscosity of solution, salt content and solvent grade and process parameters, voltage, distance, nozzle size and feeding pressure of solution. This study was performed using continuous electrospinning equipment consisting of multiple nozzles and horizontal electric field. Literature findings about the influences of certain variables are often contradictory. These contradictions and their possible causes were discussed.     

A comparison of phototautomerism in different sites of free-base porphin (H2P) in n-alkane crystals

Selective laser-induced phototautomerism of free-base porphin in different n-alkanes (n-hexane, n-heptane, n-octane, nnonane, n-decane, n-undecane and n-dodecane) has been used to identify tautomer splittings in a number of sites in polycrystalline samples at 2 K. Pairs or lines arising from the two molecular orientations in each site can be reversibly transformed into each other. In the odd n-alkanes the occupation of different sites was not dependent on the rate at which the samples were frozen, but in the even n-alkanes metastable sites were only occupied following rapid quenching.     

Experimental and DFT study of the aza-Diels-Alder reaction between cyclopentadiene and protonated benzylimine derivated from glyoxylates

The Diels-Alder reaction of protonated N-benzyl imine of methyl glyoxylate with cyclopentadiene in different solvents gave mixtures of exo/endo adducts. The exo/endo selectivity of the reaction was elucidated by NMR experiments. Theoretical calculations by means of density functional theory (DFT) at the B3LYP/6-31G(d) level have also been performed to elucidate the molecular mechanism of this reaction. The DFT results suggest a highly asynchronous concerted mechanism, which in turn can explain the preferred exo stereoselectivity of the reaction. Inclusion of solvent effects enhances the exo selectivity, and this effect increases with the polarity of the solvent, in good agreement with the experimental findings.     

PREPARATION AND STUDY ON SILICONE ACRYLATE MICRO-EMULSION OF MULTIPOLYMER

A silicone acr3,1ate micro-emulsion of multipolymer was prepared by seed emulsion polymeri.Tation. The effects of polymerization process, emulsifier rate and amount, initiator rate and amounl, polymerization temperalure, functional monomers, titration time on performances of emulsion have been discussed in detail.