固相萃取-超高效液相色谱-串联质谱法快速测定鸡蛋和鸡肉中的7种性激素药物残留量

目的建立同时测定鸡蛋和鸡肉中7种性激素类药物残留的快速检测方法。方法鸡蛋和鸡肉中的性激素类药物经乙腈-水溶液(80:20,V:V)提取后,Oasis PRiME HLB固相萃取净化,UPLC-MS/MS法检测,基质匹配外标法定量。结果该方法具有良好的准确度和精密度,在鸡蛋和鸡肉中添加回收率范围分别为78.7%～101.7%和77.9%～104.3%,相对标准偏差(relative standard deviation, RSD)低于8.7%,检出限(limit of detection, LOD,S/N=3)和定量限(limit of quantitation,LOQ,S/N=10)分别为0.02～0.5μg/kg和0.08～2.0μg/kg。结论本方法简便快速,灵敏可靠,适用于鸡蛋和鸡肉中性激素类药物残留高通量快速检测分析。     

欧洲电力线智能计量发展标准简介

低压电力线载波通信采用低压电力线作为传输介质,为通信网络“最后一公里”问题提供了一个很好的解决方案.本文介绍了一个新的基于OFDM技术的低压电力线载波通信标准——电力线智能计量发展(Power-line Intelligent Metering Evolution,PRIME),对PRIME的物理层、MAC层和汇聚层进...     

高速窄带电力线通信标准的发展和比较

随着智能电网技术的发展,传统的窄带电力线载波技术已不能满足其日益发展对通信技术的一系列要求,而高速电力线窄带通信技术的发展则为其在智能电网建设带来了新的活力。本文简单在介绍了电力线技术的发展趋势和相关标准后,着重对当前国外的主要高速电力线窄带标准－PRIME标准和G3-PLC标准及ITU-TG．hnem标准进行了分析和对比,并就高速电力线窄带标准在智能电网中的应用做了相关讨论。     

A review of degradation in single crystal nickel based superalloys

Abstract

Single crystal nickel based superalloys are in use for the front rows of blading in advanced land based gas turbines. This is for their higher creep capabilities as well as outstanding low cycle fatigue properties as compared with conventionally cast nickel based superalloys. The continuous efforts to improve the high temperature creep properties of single crystal (SX) superalloys resulted in the development of the fourth generation of these alloys. Nevertheless, this improvement in the high temperature capability of these materials required the use of higher contents of Re and Ru which increased their densities and costs. The application of SX superalloys at higher temperatures results in microstructural changes called rafting and a topological inversion of their γ/γ′ phases. These two microstructural features reduce the tensile and low cycle fatigue properties of the SX superalloys. The extent of degradation in the microstructure and mechanical properties, in a certain SX superalloy, depends on the exposure temperature, duration and to a lesser extent on the applied stress. The consequences of these changes in microstructure and properties should be taken into consideration in the evaluation of the mechanical properties of SX superalloys.     

A campus network based on ICL 2900 series protocol

A campus network has been built at the University of Salford in which a number of minicomputers have been linked to a PRIME 300/400 system using the protocol adopted for ICL 2900 series communications. This protocol is known as Extended Basic Mode, or XBM. The network is integrated into a wider regional network of ICL machines through a link to the local ICL 1904S service. The protocol defines a standard terminal model which is used as a machine-independent basis for the network construction. The benefits are described which the network brings to users both of the various minicomputers and of the PRIME system.     

Mechanical and electrical characterisation in age hardened Waspaloy microstructures

Abstract

Nickel-base superalloys such as Waspaloy possess excellent mechanical properties at elevated temperatures. This is possible through precipitation hardening, whereby submicron precipitate phases (γ′) are formed in the nickel-rich matrix phase (γ) under controlled aging heat treatments. The current work is focused on studying microstructural evolution in systematically aged Waspaloy specimens through mechanical and electrical characterisation conducted via Vickers microhardness and four probe resistivity measurements respectively. Four bars of industrial grade Waspaloy were solution treated at 1145°C and aged at temperatures of 600, 725, 800 and 875°C for times ranging from 2 min to 763·5 h. For the specimens aged at 600 and 725°C, the maximum in hardness was not reached. However, maxima in hardness and conductivity occur at similar aging times for the samples aged at 800 and 875°C. The present studies indicate that conductivity measurements show potential for ascertaining the hardness of the alloy relative to the over-aged state.     

基于OFDM的低压电力载波通讯技术及其在先进计量管理系统中的应用

着重从低压电网的干扰源、线路阻抗与衰减特性人手,结合EN50065-1标准来分析适合低压电力线路阻抗和衰减特性的载波波段、发送功率门限值、以及信号调制方式,文章介绍了OFDM(正交频分复用)及扩频通讯的技术要点与实现方式,并将它与目前常用的低压电力载波通讯方式进行了初步对比和分析;最后概要介绍了兰吉尔的AMM系统功能及其应用.     

电力线载波通信标准PRIME和G3-PLC的研究

电力线载波(PLC)通信是电力系统特有的基本通信方式。通过对当今世界上基于OFDM的两种载波通信标准PRIME和G3-PLC进行研究,主要分析了二者物理层的处理过程,并比较了其异同点,进而对两个标准的通信性能进行了对比。最后,对符合两个标准的载波方案进行了实际测试,并得出了实验结果。对不同电力线环境下载波标准的选取具有一定的参考意义。     

超高效液相色谱-单四极杆质谱联用法检测奶粉与酸奶中33种兽药残留

目的建立超高效液相色谱-单四极杆质谱(ultra performance liquid chromatography-quadrupole mass spectrometer, UPLC-QDa)同时测定奶粉及酸奶中33种(咪唑类、β受体激动剂和大环内酯类)兽药残留的检测方法。方法样品经水溶解分散后以3%(V:V)甲酸乙腈超声提取,离心后上清液用PRIME HLB固相萃取柱净化后氮吹浓缩,采用0.1%甲酸水溶液(A)和乙腈(B)作为流动相进行梯度洗脱,以选择离子监测模式对各个目标化合物定量离子进行监测分析。结果33种兽药在各自浓度范围内线性关系良好,相关系数均大于0.991。33种兽药在2种基质中的加标回收率为59.4%～108.5%,相对标准偏差(relative standard deviation, RSD)为1.68%～13.70%(n=6),检出限(S/N=3, limits of detection, LOD)和定量限(S/N=10, limits of quantification, LOQ)分别为0.06～4.66μg/kg和0.19～23.68μg/kg。结论该方法快捷简单,灵敏度高,适用于奶粉及酸奶样品中多种兽药检测。