超声提取柿果皮总三萜酸工艺优化

目的采用正交法优化柿果皮中总三萜酸的超声提取工艺。方法以"牛心柿"柿果皮为原料,利用紫外分光光度计法测定柿果皮中总三萜酸的含量,并从提取溶剂选择及其浓度、料液比、超声时间和温度等方面,通过单因素实验和正交试验确定超声提取柿果皮总三萜酸的最佳条件。结果最佳超声提取工艺为:在超声功率240 W的前提下,提取溶剂为75%(V/V)的乙醇、料液比1:15(m/V)、时间45 min、温度50℃。在此条件下,柿果皮总三萜得率最高可达39.33mg/g。结论优化后的方法简单、快速、准确、提取率高,适合提取柿果皮的总三萜酸。     

Multivariate analyses of the physicochemical properties of turnip (Brassica rapa L.) chips dried using different methods

Abstract

The turnip is a traditional “medicine food homology” vegetable in China, but the processing of it remains traditional and limited. To increase and diversify the consumption of turnips, freeze drying (FD), explosion puff drying (EPD), infrared drying (ID), and hot air drying (AD) were used to produce turnip chips. FD chips maintained most of the starch, total sugar, vitamin C, and volume ratio, followed by EPD chips, which exhibited better crisp values and rehydration rate. These results suggest EPD as a favorable method for turnip chip production. The physicochemical properties of turnip chips dried using different methods differed greatly from each other. Principal component analysis revealed that FD produced the best chips, followed by EPD. Hierarchical cluster analysis and orthogonal projection on latent structure-discriminant analysis identified the volume ratio as the characteristic property of FD chips and the contents of soluble dietary fiber and insoluble dietary fiber as the characteristic properties of ID chips, which indicated that multivariate analyses may be used to classify dried products and identify their characteristic properties.     

真菌群体感应分子法尼醇及其作用机制

群体感应(quorum sensing,QS)是取决于细胞密度的微生物通信机制,可调节细菌毒力因子分泌、生物膜形成、感受态和生物发光等行为。真菌群体感应系统10年前在法尼醇控制致病多态性真菌白色念珠菌中的细丝化研究中被发现。研究显示法尼醇作为群体感应分子(QSM)对宿主和其他微生物发挥多种作用;还发现芳香醇酪醇是控制白色念珠菌生长、形态发生和生物膜形成的另一群体感应分子。在酿酒酵母中,发现另两种芳香醇苯乙醇和色氨酸是在氮饥饿条件下调节形态发生的群体感应分子。此外,类似于群体感应的种群密度依赖性行为已在几种其他真菌中描述。本综述总结了目前发现群体感应效应的几种关键真菌物种,并重点阐述了研究较多的白色念珠菌和法尼醇作用的微观机制研究进展。     

Influence of dicalcium phosphate dihydrate coating on the in vitro degradation of Mg-Zn alloy

To reduce the degradation rate and further to improve the biocompatibility of magnesium alloy, dicalcium phosphate dihydrate (CaHPO₄·2H₂O, DCPD) has been fabricated on a kind of magnesium-zinc alloy by way of electrodeposition method. The experimental results of XRD, SEM and EDS showed that the electrodeposited coating on the Mg-Zn alloy mainly contains the flake-like DCPD, along with some octacalcium phosphate (Ca₈(HPO₄)₂(PO₄)₄·4H₂O, OCP). After the in vitro degradation of the coated alloy in modified-simulated body fluid (m-SBF), it was proved that the coating could reduce the degradation rate effectively, and the samples were covered by calcium phosphate salts with a higher Ca/P ratio. Therefore, it indicates that compared with the bare alloy, the DCPD coating rendered a more biocompatible surface, and is a promising coating candidate for biomedical magnesium materials.     

基于对称双通道脑电信号的注意力检测

注意力不能集中是一种注意力障碍,该现象普遍存在于青少年中,这直接影响人们的学习和工作效率.传统的注意力检测方法大多依赖对表情、姿势等行为的观察,难以客观精准地反映注意力情况.随着生理检测技术的迅猛发展,基于脑电信号的注意力检测近年来受到极大的关注.然而,相关研究仍存在检测准确率不高的问题.本研究收集了155位大学生在注意力集中、注意力非集中和放松3种状态下的脑电信号,并基于信号的小波特征、微分熵特征及功率谱特征,采用多种机器学习方法对3种注意力状态进行了识别.结果表明,脑电信号的小波特征,微分熵特征及功率谱特征可以有效区分被试的注意力状态,且基于对称双通道特征的平均准确率为(80.84±3)%,其检测精度明显高于基于单通道特征的检测精度.     

红外高光谱成像仪(ATHIS)对矿物和气体的实验室光谱测量

首先介绍了热红外高光谱成像应用的独特优势,然后论述了机载热红外高光谱成像仪（Airborne Thermal-Infrared Hyperspectral Imaging System, ATHIS）灵敏度优化的设计方法,结合仪器特点介绍了实验室矿物发射光谱和气体吸收光谱测量的辐射模型,分析了样本红外光谱与温度分离的数据处理流程。在此基础上,利用ATHIS开展了矿物发射光谱和气体红外吸收光谱的实验室测量,结果表明,利用ATHIS仪器和本文建立的数据方法已具备准确反演矿物发射率光谱和气体吸收光谱的能力,后续将利用该仪器开展多平台的遥感应用试验,为未来开展星载热红外高光谱相机研制和数据处理方法奠定基础。     

基于Grefenstette编码和2-opt优化的遗传算法

将Grefenstette编码和2-opt优化算法共同运用到遗传算法中,采用一定数目的城市坐标对路径搜索进行求解。仿真试验取得良好的效果,初始路径接近最优路径,且经过122次迭代后快速得到最优路径。证明本研究提出的搜索空间路径方案实现了遗传算法可以快速收敛到最优解,同时保持较强的搜索能力,实现全局最优,又可以防止陷入局部最优。     

Characterization of proteolysis in muscle tissues of sea cucumber <Emphasis Type="Italic">Stichopus japonicus</Emphasis>

The proteolysis in muscle tissues of sea cucumber Stichopus japonicus (sjMTs) was characterized. The proteins from sjMTs were primarily myosin heavy chains (MHCs), paramyosin (Pm), and actin (Ac) having a molecular mass of approximately 200, 98, and 42 kDa, respectively. Based on SDS-PAGE analysis and quantification of trichloroacetic acid (TCA)-soluble peptides released, degradation of muscle proteins from sjMTs was favorable at pH 5 and 50°C. Proteolysis of MHCs was mostly inhibited by cysteine protease inhibitors, including trans-epoxysuccinyl-L-leucyl-amido (4-guanidino) butane (E-64) and antipain (AP). E-64 and AP completely inhibited the degradation of Pm and Ac, while iodoacetic acid showed a partially inhibitory effect. These results indicated that the proteolysis of sjMTs was mainly attributed to cysteine proteases. Avoidance of setting the tissues at 40–50°C and slightly acidic condition and inhibition of cysteine proteases are helpful for decreasing sea cucumber autolysis.     

基于测量波阻抗相位特征的三端混合直流线路纵联保护

线路的后备保护在混合直流输电系统中至关重要,但现有后备保护受分布电容和过渡电阻的影响较大,严重影响保护的可靠性和快速性。为解决上述问题,提出一种基于测量波阻抗相位特征的混合三端直流线路纵联保护方案。通过分析混合直流输电线路区内、外故障时线路两端测量波阻抗的差异性,利用S变换提取单频率的电压、电流初始行波,根据测量波阻抗相位差异构造判据区分区内、外故障。PSCAD 仿真表明,所提保护方案能可靠快速地识别区内外故障,具有较强的耐受过渡电阻的能力,并且不受故障电阻和分布电容的影响,有效提高了线路后备保护的可靠性和快速性。