红外光谱法测定洗涤剂醇的羟值

建立了傅立叶红外光谱法测定Ｃ１２～Ｃ１５的洗涤剂醇羟值的方法。考察了方法的最佳积分方式、精密度和准确性。并对现场样品进行了分析。结果表明，测定１．０～１．９ｇ／２５ｍＬ的标样时，其误差为１．０％～３．４％。对现场Ｃ１２～Ｃ１５洗涤剂醇样品进行５次平行分析，相对标准偏差为０．５３％，回收率为９７．２％。     

The effects of drying following heat shock exposure of the desert moss Syntrichia caninervis

Desert mosses are components of biological soil crusts (BSCs) and their ecological functions make assessment and protection of these mosses a high-ranking management priority in desert regions. Drying is thought to be useful for desert mosses surviving heat shock. In this study, we investigated the role of drying by monitoring the responses of physiological characters and asexual reproduction in the typical desert moss Syntrichia caninervis. Heat significantly decreased chlorophyll content and weakened rapid recovery of photochemical activity, and increased carotenoid content and membrane permeability. Lethal temperatures significantly destroyed shoot regeneration potential. In comparison with heat alone, drying significantly increased protonema emergence time and depressed protonema emergence area. Drying combined with heat accelerated water loss, followed by a decrease of photosynthetic activity. Drying had different influences on membrane permeability at different temperatures. When moss leaves were subjected to a combined stress of drying and heat shock, photosynthesis was maintained mainly due to the effects of drying on physiological activity although the cellular morphological integrity was affected. Drying caused opposing effects on moss physiological and reproductive characteristics. On the one hand, drying caused a positive synergistic effect with heat shock when the temperature was below 40 °C. On the other hand, drying showed antagonism with heat shock when the moss was subjected to temperatures higher than 40 °C. These findings may help in understanding the survival mechanism of dessert mosses under heat shock stress which will be helpful for the artificial reconstruction of BSCs.     

Antioxidant activity and phenolic composition of sumac (Rhus coriaria L.) extracts

Antioxidant activity and phenolic compounds of sumac extracts were investigated. Sumac was extracted in methanol and subjected to solvent–solvent partitioning to yield two fractions as ethyl acetate and aqueous. Methanol extract was further fractioned over Sephadex LH-20 column. Antioxidant activity of extracts and fractions were screened using ferric thiocyanate and DPPH radical scavenging methods. Phenolic composition of active fraction(s) was determined by HPLC–MS systems. Those fractions which exhibited strong antioxidant activity were rich in anthocyanins and hydrolysable tannins. While gallic acid was the main phenolic acid in the extracts, anthocyanin fraction contained cyanidin, peonidin, pelargonidin, petunidin, and delphinidin glucosides and coumarates. Pentagalloyl glucose was abundant in the hydrolysable tannin fraction. Effective scavenging concentration (EC₅₀) on DPPH radical was 0.70 μg/mL both in ethyl acetate and tannin fractions, and 5.33 μg/mL in anthocyanin rich fraction. Same extracts and fractions showed moderate lipid peroxidation inhibition effect compared with the synthetic antioxidants. The findings demonstrate that sumac can be used as a natural antioxidant.     

Free radicals formation induced by the ozonation of humic substances in aqueous medium

This laboratory study was designed to investigate the mechanism of the formation of the OH radicals during the ozonation of humic substances solutions. The evaluation of the formation of these radical species was performed by using 1,1,2-trichloro ethane (TCA) as a probe. The apparent removal of TCA observed during the ozonation treatment implies the production of secondary species that catalyze the generation of OH radicals from ozone. These species are formed by a reaction between H₂O₂, formed in-situ, and O₂ and by a radical mechanism involving reactive humic substances sites.     

TiO_2/MCM-41的制备及光催化脱色性能研究

用溶胶-凝胶法制备了不同TiO2含量的TiO2/MCM-41光催化剂,以罗丹明B为模拟有机污染物,对催化剂的光催化脱色性能进行了考察。用XRD、UV-Vis漫反射、N2吸附等方法对光催化剂进行了表征,结果表明:TiO2/MCM-41的比表面积和孔体积随TiO2含量的增加而减小,TiO2/MCM-41负载型催化剂上TiO2平均晶粒尺寸比纯TiO2的小。20%TiO2/MCM-41的光生电子-空穴分离效应最高,且光催化脱色活性最高。光催化反应体系中h+是主要的活性自由基,TiO2/MCM-41的光催化活性由材料的吸附能力和所含TiO2的光催化性能共同决定。     

羟基改性萘系减水剂的合成与优化

萘系减水剂是一种用途较广性能优越的高效减水剂,这类减水剂具有成本低、减水率高的优点,羟基改性萘系减水剂相当于在部分萘磺酸甲醛混合物的萘环上引入羟基基团,我们在通过一系列的实验优化比较之后,得到了最佳的工艺条件:当萘与萘酚的物质的量比为95∶5,总萘与硫酸的物质的量比为1∶1.3、磺化时间为2 h、水解水的量为10 mL、常压缩合时间为5 h的时候,得到的产品净浆流动度比较好,并对产品进行了红外分析,与传统的萘系减水剂进行了比较。     

LED封装胶专用增粘剂的制备

以羟基硅油、γ-（2,3-环氧丙氧）丙基三甲氧基硅烷（KH 560）、乙烯基三甲氧基硅烷等为原料,制得LED封装胶专用增粘剂。研究了增粘剂合成工艺对聚邻苯二酰胺树脂（PPA）及金属粘接性的影响。结果表明,制备增粘剂的较佳工艺为：羟基硅油、KH 560、乙烯基三甲氧基硅烷的量之比为1.0∶1.0∶0.5,二月桂酸二丁基锡的质量分数为250×10^-6,在温度60～65℃下保温反应4 h;将此增粘剂按LED封装胶总质量的1.25%加入到B组分中配成封装胶,用于5050、5730灯架的封装测试,过3次回流焊,然后在100℃沸腾的红墨水中连续煮18 h,红墨水不渗入灯珠内杯周边及底部。     

FeOOH/H_2O_2催化降解碱性品红的研究

采用FeOOH/H2O2体系对一种碱性阳离子染料进行催化降解。考察了H2O2浓度、FeOOH的投加量、碱性品红的浓度、pH对碱性品红降解的影响。结果表明,反应的较优条件是H2O2浓度为60 mmol/L,FeOOH投加量1.0 g/L;碱性品红浓度高的降解速率比较慢,浓度低的降解速率快;pH=1时,碱性品红去除率为90.9%;pH=9时,碱性品红去除率为98.9%。机理研究表明,当溶液pH小于FeOOH的零电荷点时,FeOOH表面带正电荷,与带正电荷的碱性品红之间相互排斥降低了对碱性品红的吸附作用,同时部分Fe离子发生溶解,溶解的铁离子与H2O2形成Fenton体系;当溶液pH大于FeOOH的零电荷点时,FeOOH带负电荷,碱性品红因静电力被吸附在FeOOH表面,同时与产生的羟基自由基发生反应。     

水性聚氨酯地坪涂料的研制

通过对水性聚氨酯地坪涂料各个原材料的深度筛选,合理搭配,着重研究了水性聚氨酯的成膜机理和固化剂用量的探讨.所制造出的产品具有卓越的耐水性、耐化学性、耐磨性以及良好的贮存稳定性,可直接加水涂装.特别适合于学校、医院、家庭等场合使用.     

Intramolecular 1,2- and 1,3-Hydrogen Transfer Reactions of Thiyl Radicals

This review article summarizes recent experiments on 1,2- and 1,3-hydrogen transfer reactions in thiyl radicals from cysteine and related compounds. Pulse radiolysis in combination with time-resolved UV spectroscopy was applied to monitor the equilibration of initial thiyl radicals with carbon-centered radicals at both the C_α and C_β positions of cysteine. Experiments with thiyl radicals from penicillamine and cysteamine confirmed the formation of carbon-centered radicals at these positions. Complementary evidence for the intermediary formation of carbon-centered radicals was obtained from mass spectrometry and ¹H NMR spectroscopy experiments, both of which indicated covalent H/D exchange at original C H bonds when thiyl radicals were generated in D₂O. The 1,2- and 1,3-hydrogen transfer reactions can have profound consequences for the integrity of proteins when Cys residues are oxidized to Cys thiyl radicals, which subsequently equilibrate with carbon-centered radicals.