从黄豆,向日葵籽和扁豆种子制取饮料的蛋白基质

<正>近几年来,世界各地广泛积极地研究含蛋白的营养饮料,在世界市场上已出现一些碳酸和非碳酸营养饮料,大都以黄豆作为蛋白源。提取植物蛋自质最常用的溶剂是氢氧化钠。使     

蛋品冷库霉菌调查及人工感染实验

<正>蛋品冷库系高温冷库,湿度较大,霉菌容易生长,进入冷库能明显闻出霉味,墙壁、蛋箱、蛋壳上均有肉眼可见的霉斑。冷藏蛋变质部分是霉变造成的。为了解冷库中心的霉菌菌群分布、造成蛋变质的主要霉菌、好蛋受霉菌污染后的变化情况及其相互关系,进行本次实验。     

糕点饮料中维生素C的分光光度测定法

关于饮食品中维生素C的测定,已提出了荧光法,2,4-二硝基苯肼比色法,2,6-二氯酚靛酚滴定法等多种方法。荧光法专一性强,但需要贵重的荧光分光光度计,目前尚无法普遍     

高效液相色谱法测定果蔬中的5种农药残留

目的建立高效液相色谱法测定果蔬中啶虫脒、嘧霉胺、氟虫腈、辛硫磷和哒螨灵5种农药残留。方法样品以乙腈为提取剂,NH_2固相萃取小柱净化和富集,用二氯甲烷-甲醇(97:3,V:V)溶液进行洗脱,洗脱液浓缩、定容后,以Dikma Spursil C18(250 mm×4.6 mm,5μm)色谱柱分离,水和甲醇为流动相梯度洗脱,流速为1.0 mL/min,于配有紫外可变波长检测器的高效液相色谱仪测定,外标法定量。结果 5种农药在0.1~2.0μg/mL的浓度范围内具有良好的线性关系,相关系数为0.9995~0.9998。方法定量限为0.006~0.02 mg/kg。当添加浓度在0.02、0.05、0.1 mg/kg时,5种农药在果蔬中的加标回收率达到70.2%~113.0%,相对标准偏差为2.0%~11.8%。结论该方法操作简单、快速,适用于果蔬中啶虫脒、嘧霉胺、氟虫腈、辛硫磷和哒螨灵残留的测定。     

Design and simulation of an ultrasonic linear motor with dual piezoelectric actuators

In this study, an ultrasonic linear motor with dual piezoelectric (PZT) actuators is developed. A traveling wave motion is generated on the stator by a double-sided excitation of the stator of the ultrasonic linear motor, which drives the slider that is connected to the stator. The development and design processes are described. In this paper, the principle of using an ultrasonic motor to drive a traveling wave type is presented. The structure for the ultrasonic linear motor is then demonstrated with its dimensions, driving conditions and material parameters, so that Computer-Aided Engineering (CAE) can be used to simulate the driving performance. The simulation results show the differences to the characteristics that are achieved by adjusting the critical parameters, such as the PZT boned positions, the excitation frequency and the preload, in order to derive the best design. A prototype that uses the best parameter design is presented, and a method to improve development processes is presented in the final section.

     

容迟容断网络路由协议研究

容迟容断网络近年来得到了广泛的研究和应用.容迟容断网络中源节点和目的节点之间不存在持续稳定的端到端路径,因而传统网络的路由协议无法适用于容迟容断网络.为了完成容迟容断网络消息传输,采用基于存储-转发的路由机制.容迟容断网络路由协议性能受链路生存时间、节点缓存大小以及网络中节点移动模型等影响.对容迟容断网络路由协议的研究和进展进行了较为深入的探讨,对主要路由协议的性能进行了比较,并总结了未来的研究方向.     

黄曲霉菌在蜜饯、水果罐头上生长及其产毒能力的试验

<正>黄曲霉菌能在花生玉米和其他许多农产品上产生黄曲霉毒素(AFT),引起人和动物的急慢性中毒,并具有明显的致癌力,国内外有关报导甚多,已为人们所熟知。一般食品在制备、储藏、运输和销售过程中,不可避免地受环境中的菌丛,甚至产毒菌株所污染。由于霉菌的生活力强,对高     

A new calibration method for parallel kinematics machine tools using orientation constraint

This paper considers the problem of improving the accuracy of parallel kinematics machine tools through a low-cost and effective calibration method. A novel orientation constraint of keeping two attitude angles of the end-effector constant is presented to derive the calibration algorithm with special insight on the effect of using various combinations of two angles. The orientation constraint of the selected combination is realized physically through leveling a commercial biaxial inclinometer installed on the end-effector. Benefits of the proposed method include exempting the needs for precise pose (position and orientation) measurement and for mechanical fixtures, as well as rendering the independence of the measuring range and angular positioning accuracy of the inclinometer. Simulation based on the geometry of the Stewart platform of XJ-HEXA shows the position and orientation accuracy can reach 0.1 mm and 0.01° after calibration, when using an inclinometer with the repeatability of 0.001° and measuring the leg lengths with the precision of 0.002 mm at 80 configurations. Experiments on XJ-HEXA further verify the effectiveness of the proposed method.     

超高效液相色谱-串联质谱法测定动物源性食品中的金刚烷胺

目的建立超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)测定动物源性食品(鸡肉、鸡肝、鸡蛋和牛奶)中金刚烷胺的分析方法。方法样品用0.2%(V:V)甲酸乙腈溶液提取,经Oasis PRiME HLB小柱净化后用Capcell Pak C18 MGIII-H色谱柱分离,以甲醇和0.1%甲酸水溶液(V:V)作为流动相进行梯度洗脱,在多反应监测(multiple reaction monitoring,MRM)模式下进行液相色谱-串联质谱法测定,基质匹配标准溶液外标法定量。结果金刚烷胺在1.0~50.0μg/L范围内线性关系良好(r~2=0.9994)。在添加水平为1.0,5.0和20.0μg/kg时的回收率为76.3%~93.5%,相对标准偏差(relative standard deviation,RSD)在3.4%~8.6%之间,方法的检测限(limit of detection,LOD)为0.2μg/kg,定量限(limit of quantification,LOQ)为1.0μg/kg。结论该法简便、灵敏、准确,适合于动物源性食品中金刚烷胺的快速分析测定。     

Effect of electro-optic modulation on coupled quasi-phase-matched frequency conversion

The electro-optic effect can be employed to modulate the refractive index of an optical superlattice. In coupled quasi-phase matched processes, this modulation will introduce quasi-phase mismatches and result in energy redistribution among the optical waves. Numerical results indicate that an efficient third harmonic in a periodic or quasi-periodic superlattice can be achieved by varying the external dc electric field. This method provides a simple and convenient way to control the efficiencies of frequency conversion.