Radical scavenging activity of canola hull phenolics

Possible use of canola hulls as a source of natural anti-oxidants was explored. Cyclone canola hulls were extracted with methanol (30 to 80%, vol/vol) and acetone (30 to 80%, vol/vol). The free radical-scavenging activity of phenolic extracts so prepared was evaluated using the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical ion (ABTS^o−), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and chemiluminescence assays. The total content of phenolics in prepared extracts from canola hulls ranged from 15 to 136 mg sinapic acid equivalents per gram of extract. Higher levels of condensed tannins were detected in the acetone extracts than in the corresponding methanolic counterparts. Seventy and 80% (vol/vol) acetone extracts displayed markedly stronger antioxidant activity than any of the other extracts investigated. Statistically significant linear correlations were found between TEAC (Trolox equivalent antioxidant capacity) values (expressed in mM of Trolox equivalents per gram of extract) and total pehnolics, TEAC and total condensed tannins (i.e., determined using the modified vanillin and pronthocyanidin assays), as well as TEAC and protein precipitation activity of phenolic extracts (i.e., measured using the dye-labeled assay). The antioxidant activities of extracts as determined by the ABTS^o− radical ion assay correlated highly with those of the chemiluminescence and DPPH radical assays.     

酚醛环氧乙烯酯树脂研究

本文以酚醛环氧树脂F-51与甲基丙烯酸合成出酚醛环氧乙烯酯树脂,并对此树脂的耐热性、耐化学溶剂性能进行了研究.     

Modelling of solvent positions around polar groups in proteins

Previous analysis of the distribution of experimental solventmolecule positions around amino acid side chains showed thatdistinct clustering occurred close to polar or charged atomsin proteins. We have used those data to predict likely solventpositions around proteins not used in our initial analysis.We envisage that this algorithm, AQUARIUS, will be useful forfinding solvent positions in electron density maps generatedby protein crystallography and as useful starting positionsfor solvent molecules in computer simulation studies of macromolecules.     

水溶性香豆素衍生物的合成及其光谱性能

4-甲氧基水杨醛和丙二酸二乙酯反应合成了中间体7-甲氧基香豆素-3-甲酸,该中间体与二乙醇胺反应合成了水溶性香豆素类衍生物7-甲氧基香豆素-3-甲酰二乙醇胺。用核磁共振(NMR)表征了产物的结构,研究了其紫外吸收光谱和荧光光谱。     

硫代磷酸/伯胺N1923协同萃取锌和镉的机理

有机硫代磷酸/伯胺N1923协同萃取锌、镉的萃取率随pH的变化较为反常，可能因伯胺N1923与硫酸作用进而聚为反向胶束. 实验表明，如以(N1923)n.H2SO4表示反向胶束的实验式，N1923与H2SO4比值n多为3左右，可能与空间效应相关. 萃取机理为: M2+(a) +2BHA(o) + (2/n)SO42–(a) = MA2(o) + (2/n)(Bn.H2SO4)(o) + 2(1–2/n)H+(a)， n=3, 4, 5.     

PVC-U异型材塑化度的评价

比较了4种评价PVC-U塑化度的方法:目测法简单;溶剂法迅速,容易操作;拉伸法可定量判断,但需要大量样品;DSC法准确、方便。     

非有机溶剂液/固萃取分离在分析化学中的应用进展

非有机溶剂液-固萃取分离体系是近十几年发展起来的一种新型高效分离技术,它有两种萃取体系:1)聚合物-盐-水液-固体系;2)盐-三元缔合物-水液-固体系.由于此分离技术具备分离设备简单、速度快、收率高、不使用有毒有机溶剂等特点,受到研究人员的高度关注,目前已经广泛应用到金属离子分离和生物活性物质纯化过程中.重点阐述了该体系的基本原理、影响分离效率的有关因素及研究进展,并对下一步发展进行了展望.     

用Simha-Somcynsky状态方程改进高分子中溶剂扩散系数模型

将Simha-Somcynsky状态方程和Vrentas-Duda的自由体积理论模型相结合，提出改进的高分子中溶剂扩散系数模型.改进的模型利用状态方程和WLF理论定义的自由体积分数确定扩散过程的有效自由体积，避免原模型中繁琐的黏弹性实验测定.对苯、甲苯、乙苯、氯仿在聚苯乙烯、聚异丁烯和聚醋酸乙烯酯中的扩散系数的计算结果表明，改进模型的预测值与实验值取得较好一致，且自扩散系数的预测精度比原模型高.同时，改进的模型能够反映压力对扩散系数的影响.溶剂扩散系数随外界压强增加而减小，当溶剂浓度较低时，压强的影响非常显著，扩散系数可相差几个数量级.随着溶剂浓度升高，扩散系数接近常压时的扩散系数，压强影响可以忽略.     

现代核磁共振技术及其在新药创制中的应用

简述了核磁共振技术的基本原理和最新进展 ,讨论了现代NMR技术在新药创制中的应用     

Production of propylene glycol fatty acid monoesters by lipase-catalyzed reactions in organic solvents

Fatty acid monoesters of propylene glycol (1,2-propanediol) are good water-in-oil emulsifiers. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. APseudomonas lipase was added to reaction mixtures containing propylene glycol and various acyl donors (fatty acids, fatty acid ethyl esters, fatty acid anhydrides and triglycerides) in organic solvents, and the mixtures were shaken at 30°C. The products were analyzed by gas chromatography. The yield of monoesters was affected by the acyl donors, organic solvents, temperature, water content, pH memory and reaction time. The anhydrous (lyophilized) enzyme and fatty acid anhydrides were best for monoester production. The optimum pH ranges were 4–5 and 8–10. The yields of propylene glycol monolaurate, monomyristate, monopalmitate, monostearate and monooleate with 50 mM fatty acid anhydrides as acyl donors were 97.2, 79.6, 83.7, 89.7 and 93.4 mM, respectively; those with 50 mM fatty acids as acyl donors were 37.3, 28.7, 28.7, 35.3 and 36.2 mM, respectively. The yields of propylene glycol monopalmitate, monostearate and monooleate with 50 mM triglycerides as acyl donors were 87.4, 65.1 and 83.2 mM, respectively.