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.     

基于高分辨卫星影像的城市用地不透水率分析

不透水地面是城市地区的特征，它与总用地的比值～不透水率作为一个重要的城市生态指数常出现于城市水文、城市水质面源污染以及城市植被制图等研究中。本文借助高分辨率卫星影像首次在我国城市中心城区尺度上探索土地利用的不透水性。基于对南京5个典型城市功能区中555个有效用地斑块样本的不透水率数据的分析表明，不同土地利用类型的不透水率在统计上存在显著性差异，建设用地中绿地的不透水率最低（0%～30%），市政设施用地的不透水率最高(80%～100%)，居住与道路广场用地的不透水率接近，而工业用地的不透水率相对较低(40%～75%)，平均城市建设用地不透水率约69%。该结果填补我国城市用地不透水率研究的空白，为城市水文模拟研究提供下垫面参数，并可望用于城市土地利用的生态规划。     

A Comparison of Statistical Models for Calculating Reliability of the Hoffmann Reflex

The Hoffmann reflex is obtained through surface electromyographic recordings, and it is one of the most common neurophysiological techniques in exercise science. Measurement and evaluation of the peak-to-peak amplitude of the Hoffmann reflex has been guided by the observation that it is a variable response that requires multiple trials to obtain a stable mean. As a result, reliability assessment of the Hoffmann reflex has thus far been limited to trial-to-trial variability or the mean of multiple trials across test days to evaluate day-to-day variability, without considering how the two dimensions of measurement interact to affect test–retest reliability. This article compares two analysis of variance models for reliability assessment of the peak-to-peak amplitude of the Hoffmann reflex: one model incorporated both days and trials, and the other used the mean of multiple trials on each test day. The intraclass correlation coefficient calculated from an analysis of variance model that incorporated both trial-to-trial and day-to-day error variances was R = .93. Using the mean of the trials for each test day as a single score resulted in a decrease in the intraclass correlation coefficient (R _2,1 = .76). This study demonstrated that an analysis of variance model that accounts for both trial-to-trial and day-to-day error variances provided a higher estimate of reliability. Further, reliability estimation based on the interaction between both trials and days revealed that a schedule with additional test days had a disproportionate impact upon securing a reliable measure of Hoffmann reflex amplitude.     

Efficacy of current and novel electromyographic normalization methods for lower limb high-speed muscle actions

Abstract

The aim of this study was to assess the efficacy of electromyography (EMG) normalization methods for a high-speed 20-m sprint. Comparisons were based on intra-individual reliability and magnitude of normalized EMG signals from three repeat sessions separated by 1 day (between days) and 1 week (between weeks) from the initial test. Surface EMGs were recorded (n=16) from the medial and lateral gastrocnemius and soleus during the normalization methods (isometric: maximum/sub-maximum/body weight; isotonic: maximum/sub-maximum/body weight; isokinetic: 1.05 rad · s^–1, 1.31 rad · s^–1, 1.83 rad · s^–1; squat jump). The EMG data from the 20-m sprint were normalized using each method and using the within-sprint peak EMG (sprint peak). Intra-individual reliability of the EMG was assessed using typical error of measurement as a percentage of intra-individual coefficient of variance (TEM_CV%). Sprint peak normalization improved intra-individual reliability of EMG (soleus: <4.91_CV%; medial gastrocnemius: <6.2_CV%; lateral gastrocnemius: <7.1_CV%) compared with un-normalized EMG (soleus: <13.3_CV%; medial gastrocnemius: <16.5_CV%; lateral gastrocnemius: <16.3_CV%) both between days and between weeks. Squat jump normalization improved the soleus (<11.2_CV%) and medial gastrocnemius (<15.7_CV%) reliability between days and weeks and provided a representative measure of triceps surae muscle activation. The intra-individual reliability of the medial gastrocnemius EMG data was improved both between days and weeks when using isotonic normalization. Isometric and isokinetic normalization showed no improvement in intra-individual reliability either between days or weeks for any muscle. The method of normalization influenced the between-stride muscle interaction during the 20-m sprint. The results of this study suggest that peak normalization can be used to normalize high-speed muscle actions, while normalizing EMG to a squat jump may provide an alternative method to represent relative muscle activation.     

船房河流域污染物排放规律研究

随着我国经济建设的快速发展,水环境问题成为当下越来越关注的问题。城市面源污染具有初始冲刷效应,不同下垫面、功能区的污染特性不同。而现阶段我国对城市面源的研究和管理相对滞后,文章基于昆明市船房河流域污染特征的具体情况,利用城市下垫面监测、雨水/雨污合流排放口监测、地表径流监测的方法,科学的对生活用水量、废水和污染物排放量进行研究,有利于合理开发城镇水资源以及制定相关废水治理规划和政策。     

轴向进给量对车铣表面微观几何形貌的研究

文章建立球头铣刀正交车铣加工件表面微观几何形貌的数学模型,研究不同的轴向进给量对加工表面微观几何形貌的影响,为在车铣加工中其他的切削用量参数加工的表面微观几何形貌提供一定的参考评价机制。     

崩塌灾害的定量评价

通过对崩塌机理的分析,以及大量崩塌实例考察,对崩塌进行了定性分析,总结出判断崩塌发生可能性的定量指标.对影响崩塌发生的定量指标进行综合分析,运用回归分析总结出崩塌发生的可能性判别式.通过对实例的分析与规范验证对比,证明了模型的正确性.     

超导能隙的理论及计算

应用ＢＣＳ理论，借助二次量子化方法，系统论述了超导能隙的概念和基本理论，并对Ｔ≤Ｔｃ的各个温区的能隙进行了详细的计算。     

有限群在可定向闭曲面上反向自由作用的等价性(英文)

设φ1,φ2∈ORF(G,Tnr+1)对应于满同态1,2∈EP2(π1(Unr+1),G),本文证明了φ1,φ2等价当且仅当1,2等价.