Optimization of extraction of phenolics from leaves of Ficus virens

In this research, the conditions for extraction of phenolics from leaves of Ficus virens were optimized using response surface methodology (RSM). The extraction abilities of phenolics (EAP) and flavonoids (EAF), the 2,2-diphenyl-1-pierylhydrazyl (DPPH) free-radical scavenging potential, and the ferric reducing/antioxidant power (FRAP) were used as quality indicators. The results of single-factor experiments showed that temperature, ethanol concentration, extraction time, and the number of extraction cycles were the main influencing variables, and these provided key information for the central composite design. The results of RSM fitted well to a second degree polynomial model and more than 98% of the variability was explained. The ideal extraction conditions for EAP, EAF, DPPH free-radical scavenging potential, and FRAP were obtained. Considering the four quality indicators overall, the ideal extraction conditions were 58% ethanol at 57 °C for 37 min with three extraction cycles. At the ideal extraction conditions, the values of EAP, EAF, DPPH free-radical scavenging potential, and FRAP were 5.72%, 3.09%, 58.88 mg ascorbic acid equivalent (AAE)/g dry weight (DW), and 15.86 mg AAE/g DW, respectively. In addition, linear correlations were observed between EAP, EAF, and antioxidant potential.     

RSM与高校图书馆的管理创新

引入工商企业界的CSM(用户满意管理)，探索符合我国高校图书馆实际的RSM(读者满意管理)创新，有助于我国高校图书馆在“复合图书馆”时代形成以读者为本的管理取向与模式。     

Influence of medium components on elastase production using crudesources by Bacillus sp. EL31410

ＩＮＴＲＯＤＵＣＴＩＯＮＡｎｉｎｃｒｅａｓｉｎｇｄｅｍａｎｄｆｒｏｍｃｏｎｓｕｍｅｒｓｆｏｒｈｅａｌｔｈｙａｎｄｌｏｗｃｏｓｔｍｅｄｉｃａｌｓｈａｓｌｅｄｔｏｔｈｅｄｅ ｖｅｌｏｐｍｅｎｔｏｆａｌｔｅｒｎａｔｉｖｅｍｅｄｉｃａｌｔｈｅｒａｐｙａｇｅｎｔｓｕ     

Optimization of antioxidant activity by response surface methodology in hydrolysates of jellyfish (Rhopilema esculentum) umbrella collagen

To optimize the hydrolysis conditions to prepare hydrolysates of jellyfish umbrella collagen with the highest hydroxyl radical scavenging activity, collagen extracted from jellyfish umbrella was hydrolyzed with trypsin, and response surface methodology (RSM) was applied. The optimum conditions obtained from experiments were pH 7.75, temperature (T) 48.77 °C, and enzyme-to-substrate ratio ([E]/[S]) 3.50%. The analysis of variance in RSM showed that pH and [E]/[S] were important factors that significantly affected the process (P<0.05 and P<0.01, respectively). The hydrolysates of jellyfish umbrella collagen were fractionated by high performance liquid chromatography (HPLC), and three fractions (HF-1>3000 Da, 1000 Da<HF-2<3000 Da, and HF-3<1000 Da) were collected. The HF-2 fraction had the highest hydroxyl radical scavenging activity with the highest yield compared with the other two fractions. Furthermore, HF-2 also showed the strongest Cu²⁺-chelating ability and the best tyrosinase-inhibitory activity. Project (No. 2008BAD94B07) supported by the Hi-Tech Research and Development Program (863) of China     

Optimization of antioxidant activity by response surface methodology in hydrolysates of jellyfish (Rhopilema esculentum) umbrella collagen

To optimize the hydrolysis conditions to prepare hydrolysates of jellyfish umbrella collagen with the highest hydroxyl radical scavenging activity, collagen extracted from jellyfish umbrella was hydrolyzed with trypsin, and response surface methodology (RSM) was applied. The optimum conditions obtained from experiments were pH 7.75, temperature (7) 48.77 ℃, and enzyme-to-substrate ratio ([E]/[S]) 3.50%. The analysis of variance in RSM showed that pH and [E]/[S] were important factors that significantly affected the process (P<0.05 and P<0.01, respectively). The hydrolysates of jellyfish umbrella collagen were fractionated by high performance liquid chromatography (HPLC), and three fractions (HF-1>3000 Da, 1000 Da相似文献   

规则空间模型在口腔内科分数报告中的应用研究

规则空间模型是一种基于统计模式识别和分类的认知诊断理论,能够提供关于考生作答模式与属性掌握情况的详细信息。本研究运用该模型,在详细考察口腔内科学知识属性的基础上,对参加2006年口腔执业医师考试的454名考生进行诊断,最后得到八种典型反应模式,并将454名考生的实际作答模式判归为这八种典型反应模式,从而实现对考生口腔内科学知识属性掌握的识别及其分类,针对我国执业医师考试分数报告的形式和内容提出了改进建议。     

发酵法菜籽饼脱毒的微生态研究

本试验用FDM RM-1(Fully Detoxicating Microbes to Rapeseed Meal-1)为脱毒菌剂进行发酵法菜籽饼脱毒过程中的微生态研究。证明在发酵过程中,发酵温度条件不同,发酵过程中pH变化状态不同,发酵过程中品温变化也不同。试验证明了菜籽饼的脱毒作用主要是由细菌、霉菌引起,放线菌次之。环境温度25℃最为适宜,在25℃条件下品温变化较理想,GS的降解率96.8%,植酸降解率94.5%,单宁的降解率93.7%.     

Influence of medium components on elastase production using crude sources by Bacillus sp. EL31410

A newly isolated strain EL31410, producing elastase (E.C3.4.4.7) with high elastolytic activity was identified as Bacillus sp. In the medium optimization, it was found that wheat bran and soybean flour hydrosate were the best crude carbon and nitrogen source for enzyme production, respectively. Addition of corn steep flour can affect the bacterium growth and elastase production. A fractional factorial design was applied to study the main factors that affect the enzyme production, and central composite experimental design and response surface methodology were adopted to derive a statistical model for the effect of wheat bran and soybean flour hydrosate on elastase production. The experimental results showed that wheat bran had positive effect but soybean flour hydrosate had negative effect, on enzyme production. An initial concentration of 3.4%(w/v) wheat bran and 9.4%(v/v) soybean flour hydrosate were found to be optimal for enzyme production in batch culture. The time course of elastase production in the optimized medium composition was also described.     

认知诊断评估中知识状态估计方法简述

尽管认知诊断评估的方法或模型众多,但其最终目的都是要报告被试属性掌握的强项与不足,即对被试的知识状态进行估计或分类。本文主要对规则空间模型、属性层级模型、确定性输入噪音与门模型和其他几个模型下知识状态估计方法进行简述,重点介绍各知识状态估计方法的基本思想、优缺点及它们内在的联系与区别。最后,概述影响知识状态估计结果的因素,并提出应进一步研究的问题。     

响应面分析法优化3-羧基水杨醛的合成

采用响应面分析法以水杨酸为原料合成3-羧基水杨醛。通过单因素实验,确定响应面实验因素与中心水平。根据Central Composite Design(CCD)实验设计原理,采用三因素三水平的响应面法,以合成产率为响应值,分析各个因素的显著性和交互作用。结果表明:最佳合成条件为反应时间4.30 h,反应温度80.62℃,氨水加入量14.69 mL。此条件下合成产率为4.40%。该合成工艺条件产率较高且稳定,可以作为3-羧基水杨醛合成的理论依据。