The effect of modifiers on the stability of a vinyl acetate/ethylene copolymer dispersion

This paper examines the effect of modifiers on the stability of a vinyl acetate/ethylene copolymer dispersion adhesive upon aging. Eighteen common modifiers were added to a well-characterized vinyl acetate/ethylene copolymer dispersion (Dur-O-Set^® E-150) in known concentrations and dry-film samples were subjected to 16–17 years of dark aging and seven to eight years of light aging. Yellowing, pH, gloss, swelling, cohesive strength, and flexibility were monitored for changes upon aging. Generally, the neat Dur-O-Set^® E-150 (no additives) was found to become acidic on aging, but was fairly resistant to yellowing. It also swelled substantially in toluene, was of high gloss, medium strength, and flexible, and remained so on aging. No modifier was found to improve these properties. Various solvents, wetting agents, and thickeners did not alter the properties by much, while plasticizers, freeze-thaw stabilizer, glycerin, and certain fillers had a more negative effect.     

3,7-二甲基-2-十三碳醇乙酸酯的合成——松叶蜂Diprion pini性信息素活性组分

对松叶蜂 diprion pini性信息素活性组分 3,7-二甲基 -2 -十三碳醇乙酸酯的全合成进行了研究 .以丙二酸二乙酯和 2 ,3-环氧丁烷为原料 ,分别合成了两个重要结构单元—— 2 -甲基 -1-辛烷基锂和 3,4-二甲基 -γ-丁内酯 .2 -甲基 -1-辛烷基锂与 3,4-二甲基 -γ-丁内酯反应 ,得到的酮醇再经黄鸣龙还原 ,得到 3,7-二甲基 -2 -十三碳醇 ,经酯化 ,得到 3,7-二甲基 -2 -十三碳醇乙酸酯     

稀土复合固体超强酸SO_4~(2-)/TiO_2/Ce~(4+)催化合成乙酸环己酯及动力学研究

研究了以稀土复合固体超强酸SO42-/TiO2/Ce4+为催化剂合成乙酸环己酯的反应,在反应温度分别为100℃、110℃、120℃下,测出酯化反应的动力学参数,建立了动力学方程,并与无催化剂作用下合成乙酸环己酯反应的活化能及动力学方程进行了比较.实验结果表明,该催化酯化反应的优化合成条件是:乙酸用量为0.262 1mol时,醇酸摩尔比为1.5:1,催化剂用量为1.0g,带水剂环己烷的加入量为12mL.稀土复合固体超强酸SO42-/TiO2/Ce4+可使反应的活化能明显降低,是合成乙酸环己酯的有效催化剂.     

“NSB”组合配方对油菜籽产量和品质的影响

分别在油菜的蕾苔期、初花期喷施一定浓度的植物生长调节剂萘乙酸、微量元素锶和硼的混合配方，可以有效地促进植株生长发育；增强油菜光合作用；提高油菜花蜜腺的泌蜜量；同时，主花序有效长度增长；分枝部位降低；千粒重和角果数增加；发病率降低，从而使油菜籽产量增加１２％以上；含油率增加４％以上；品质显著改善。微量元素增加；其中锶增加最为明显。     

石墨炉原子吸收直接法测定海水镍和钒

本文研究了海水基体和共存离子对镍和钒的影响,选用酒石酸、乙酸铵分别作为镍和钒的基体改进剂。未加基体改进剂前,海水镍回收率只有77％,钒的测量精度为11％;加人改进剂后均有改善。采用塞曼效应背景校正技术,热解涂层石墨管,建立了石墨炉原子吸收直接测定海水镍和钒的分析方法。镍和钒的特征质量值(mo)分别为8.4pg和17pg;实际检测限:镍为0.25μgL~(-1)和钒为0.41μgL~(-1)。回收率镍为86～110％,钒为88～106％范围。最大相对标准偏差为谋5.5％,钒4.2％。     

活性白土负载磷钨酸催化合成乙二醇单乙醚醋酸酯

以醋酸和乙二醇单乙醚为原料，活性白土负载磷钨酸作为催化剂，合成了乙二醇单乙醚醋酸酯。考察了不同反应条件对产率的影响。最佳反应条件为：磷钨酸固载量35％、催化剂焙烧温度180℃、催化剂用量为醇醚质量的5％、酸醇摩尔比为1．2：1、带水剂甲苯用量为反应物质量的15％和反应时间为1．5h，产率可达到99％。     

Effects of short-term hormone replacement on atherogenic indices in Indian postmenopausal women

Indian ethnicity by itself is a strong risk factor for development of CAD in Indian postmenopausal women due to lower HDL levels as compared to Whites and women of oriental origin. We evaluated and compared the short-term effects of menopause, estrogen replacement therapy and combined estrogen and progestin replacement therapy on various atherogenic indices. 40 postmenopausal women, both surgical and natural (20 each) were selected. 10 surgical postmenopausal women were given 0.625 mg conjugated estrogens daily for 6 months and 10 natural postmenopausal women were given 0.625 mg conjugated estrogen with 2.5 mg medroxyprogesterone acetate daily. 20 women were included in the control group and given placebo. Fasting venous blood samples were analyzed for extended lipid profile and calculated atherogenic indices before starting the therapy and after 1,3 and 6 months. LDL and Apolipoprotein B increased (p<0.05) and those of Apolipoprotein A1 and HDL decreased in the control groups. In both the study groups levels of serum cholesterol and LDL decreased (p<0.05) and those of HDL and Apolipoprotein A1 increased (p<0.01). LDL/HDL, Apo B/ApoA1, Total Cholesterol/HDL decreased significantly (p<0.05) in both the study groups compared to the control groups. The effect of estrogen alone was more significant as compared to combination therapy. Log Triglycerides (TG)/HDL ratio showed a decrease in women on estrogen alone but the difference was not significant. Our study confirms that short term HRT has a favorable effect on atherogenic indices in Indian postmenopausal women.     

扁担杆乙酸乙酯部位镇痛作用

研究扁担杆乙酸乙酯部位的镇痛作用。采用化学方法制备扁担杆乙酸乙酯部位。采用热板法和醋酸致小鼠扭体实验观察乙酸乙酯部位对小鼠的镇痛作用。结果发现低浓度扁担杆乙酸乙酯部位能能明显提高小鼠痛域值并减少醋酸致小鼠扭体次数;中浓度乙酸乙酯部位可以减少醋酸致小鼠扭体次数,但对小鼠痛域值并没有影响。实验结果提示扁担杆乙酸乙酯部位具有一定镇痛作用。     

无机盐催化合成乙酸正丁酯的研究

实验研究了FeCl3·6H2O、Fe(So4) 3·XH2O、CuCl2·2H2O、NaHSO4·H2O、TiSO4、SnCl4·5H2O、AlCl3·6H2O、ZnSO4·7H2O、CuSO4·2H2O等几种无机盐对乙酸与正丁醇酯化反应的催化剂的催化性能的影响.结果表明:FeCl3·6H2O、Fe(SO4)3·XH2O、CuCl2·2H2O、NaHSO4·H2O、TiSO4、SnCl4·5H2O、AlCl3·6H2O都是较好的催化剂,同时,研究了以上几种无机盐催化剂合成乙酸正丁酯的最佳反应条件、特点并得出用以上催化剂重新组合的FeCl3-CuCl2,Fe(SO4)3-CuCl2按质量的2:1组合成混合催化剂重复性更好.     

乙酸乙酯制备实验的改进

本文报道了一种乙酸乙酯合成实验的改进方法,并提出了催化剂浓硫酸用量的最佳值.