二次酸水解法从黄姜中提取薯蓣皂甙元的工艺

薯蓣皂甙元是合成甾体激素药物和甾体避孕药物的重要原料,是黄姜中的主要活性物质。采用正交实验的方法,探讨了经过二次酸水解法从黄姜中提取薯蓣皂甙元的工艺条件,结果表明该方法提取的薯蓣皂甙元产率达到了2.41%,比直接水解法(2.20%)提高了9.55%。另外,采用熔点、元素分析法、红外、核磁等一系列的手段对产品进行表征,结果表明该法是可行的,提取的薯蓣皂甙元的质量纯度达到了工业的要求。     

林地腐殖土腐植酸对毒死蜱水解影响及吸附作用

采用平衡振荡法研究腐植酸对毒死蜱水解的影响和毒死蜱在腐植酸上的吸附特征及其影响因素.结果表明,在试验浓度范围内腐植酸可促进毒死蜱的水解,腐植酸浓度为120 mg/L时,毒死蜱的水解速率常数k明显增大,为不加腐植酸时的2.53倍,腐植酸浓度增加毒死蜱的水解速率降低.毒死蜱在腐植酸上的吸附行为均可用Linear方程和Freundlich方程来描述,拟合效果均达到显著水平;试验条件下温度为15℃时毒死蜱在腐植酸上的吸附量最大,随温度的升高吸附量呈现出先降低后增大的趋势;pH值减小,腐植酸对毒死蜱的吸附能力增大;而离子强度对毒死蜱的吸附影响不明显;腐植酸添加量越大,吸附量越大,但单位质量的腐植酸吸附量越小.     

硫酸尿素系统化学反应的研究

研究了硫酸尿素系统在不同配比和不同温度的化学反应。结果表明，常温下硫酸与尿素的摩尔比为1：1．0和1：2．0时，可形成有固定熔点的晶体。其相变点温度在硫酸和尿素相变温度之间，相变热远远小于尿素。80～90℃时，硫酸尿素水溶液系统会发生水解反应，过程速率为二级，且水解速率远大于尿素水溶液系统；150℃以上时，硫酸尿素系统发生反应生成氨基磺酸硫酸铵。在工程设计和应用中，应严格控制硫酸尿素系统在80～90℃的停留时间，并保证系统温度不超过150℃。     

微波促进二氯菊酸甲酯的水解新工艺研究

采用微波技术对二氯菊酸甲酯在NaOH溶液中水解为二氯菊酸工艺进行了研究。结果表明,微波促进下最佳水解条件为:反应温度90℃,功率100 W,反应时间10 m in,物质的量比n(二氯菊酸甲酯)∶n(C2H5OH)∶n(NaOH)=1∶4∶1.5,重结晶后收率高达99.6%。与传统条件相比,时间缩短30倍,收率提高24.6%,无水乙醇用量减少60%,NaOH用量减少17%。并用红外光谱和熔点对二氯菊酸进行表征。     

Hydrolysis of fats and oils with moist oat caryopses

To improve the economic feasibility of hydrolyzing fats and oils with moist oat caryopses, various factors affecting the efficiency of the process were studied. Caryopses produced with an impact-type dehuller exhibited greater lipase activity than those produced by a wringer-type dehuller. Abrasion of oat caryopses against each other in a fluidized bed released particles rich in lipase. Such lipase concentrates could be added to moist caryopsis reactors to speed fat hydrolysis. Beef tallow, lard, soybean oil and crambe oil were hydrolyzed more efficiently than corn oil, castor oil and milk fat. The poor hydrolysis of castor oil was attributed to the formation of esters with the hydroxy group of ricinoleic acid, and the hydrolysis of castor oil was increased by dilution of the substrate with hexane. Diglycerides inhibited the hydrolysis and accounted for the slower hydrolysis of corn oil. Hydrolysis of milk fat by moist oat caryopses resulted in preferential hydrolysis of C₆ to C₁₀ acids. Erucic acid was released from crambe oil at significantly slower rates than the other acyl groups. High conversions of fats and oils to free fatty acids could be attained by (i) exposing the fats and oils to two to three lots of moist caryopses, (ii) the use of special oat varieties with elevated lipase content, (iii) the addition of oat lipase concentrates to moist caryopsis reactors, and (iv) dilution of the substrate with hexane. Estimates of the cost of producing free fatty acids with these processes indicated that the first three should be profitable. Growth ofClostridium sporogenes spores could not be demonstrated in caryopsis reactors. During the incubation of moist oat caryopses immersed in oil, the free fatty acid content of the internal caryopsis lipid increased only slightly, but there were changes in its fatty acid composition.     

Effects of amino acid replacements around the reactive site of chicken ovomucoid domain 3 on the inhibitory activity toward chymotrypsin and trypsin

We have previously shown that replacing the P1-site residue(Ala) of chicken ovomucoid domain 3 (OMCHI3) with a Met or Lysresults in the acquisition of inhibitory activity toward chymotrypsinor trypsin, respectively. However, the inhibitory activitiesthus induced are not strong. In the present study, we introducedadditional amino acid replacements around the reactive siteto try to make the P1-site mutants more effective inhibitorsof chymotrypsin or trypsin. The amino acid replacement AspTyrat the P2' site of OMCHI3(P1Met) resulted in conversion to a35000-fold more effective inhibitor of chymotrypsin with aninhibitor constant (K_i) of 1.17x10^–11 M. The K_i valueof OMCHI3(P1Met, P2'Ala) indicated that the effect on the interactionwith chymotrypsin of removing a negative charge from the P2'site was greater than that of introducing an aromatic ring.Similarly, enhanced inhibition of trypsin was observed whenthe AspTyr replacement was introduced into the P2' site of OMCHI3(P1Lys).Two additional replacements, AspAla at the P4 site and ArgAlaat the P3' site, made the mutant a more effective inhibitorof trypsin with a K_i value of 1.44x10^–9 M. By contrast,ArgAla replacement at the P3' site of OMCHI3(P1Met, P2'Tyr)resulted in a greatly reduced inhibition of chymotrypsin, andAspAla replacement at the P4 site produced only a small changewhen compared with a natural variant of OMCHI3. These resultsclearly indicate that not only the P1-site residue but alsothe characteristics, particularly the electrostatic properties,of the amino acid residues around the reactive site of the proteaseinhibitor determine the strength of its interactions with proteases.Furthermore, amino acids with different characteristics arerequired around the reactive site for strong inhibition of chymotrypsinand trypsin.     

水溶液中纳米二氧化钛光催化降解甲基橙的影响因素

用沸腾回流直接水解法制备了粒径为25～35 nm纯锐钛矿型纳米二氧化钛(TiO2).用X射线衍射和透射电镜表征材料的结构与形貌.用该催化剂催化降解甲基橙,研究了催化剂用量、甲基橙的起始浓度、溶液pH值、光强度、溶液中添加金属离子的影响.结果表明:在较强紫外光照射下,当甲基橙的起始浓度为0.02 g/L,TiO2用量为1.0g/L,光催化效率最高.酸性条件有利于光催化降解甲基橙.掺加Fe3 或Zn2 的光催化效率显著增加.掺加Mn2 或Ca2对光催化活性没有影响.在紫外光区域(366 nm),样品对催化降解水溶液中甲基橙的活性较高.     

间羟基三氟甲苯的合成

以三氟甲苯为原料，经硝化、还原、重氮化、水解等过程，可以得到重要的农药中间体间羟基三氟甲苯，产物总收率达70％以上，在较高温度下进行重氮化反应时，可以显著提高间氨基三氟甲苯重氮化、水解反应的收率。     

生物转化植物纤维产酒精的研究进展

植物纤维是潜在的可再生资源，利用微生物对其进行降解、转化以实现工业化低成本生产，已成为研究的热点。从生物方法角度对植物纤维为原料产酒精的3个阶段：原料预处理、纤维素酶糖化和发酵进行全面的阐述，包括微生物及其作用机理和处理工艺等方面的内容。     

高粘度二甲基二苯基室温硫化硅橡胶制备

探讨了水解缩聚、环体开环共聚两种合成方法制备高粘度二甲基二苯基室温硫化硅橡胶的可行性，讨论了工艺过程对产品性能的影响因素。