一种应用于车载的无线射频识别系统

本系统是基于数字通信原理、利用集成单芯片窄带超高频收发器构建的无线识别系统。阐述了该无线射频识别系统基本工作原理和硬件设计思路,并给出了程序设计方案的流程图。从低功耗、高效识别和实用角度设计适用于车载的射频识别标签。测试结果表明,本系统在复杂路面状况(繁忙路面)的条件下可实现300 m范围内有效识别,视距条件下可达到500m范围有效识别。     

仪器检测数据高效自动采集技术研究

实验数据信息管理历来是检验检疫系统技术中心的工作重点.原始数据的手工记录不仅费时费力,还很容易产生错误导致重复劳动.针对这一需求,通过开发实验室数据处理平台,实现了对不同厂家、不同型号的分析仪器检测数据高效自动采集与原始记录单的自动生成,从而减少数据手写出错的可能性,最终提高实验室的检测效率,更好地严把产品安全质量关,更好地为进出口产品生产企业服务.     

Fast Quantitative Analysis of Hidden Dangerous Substances in Mail Based on Specific Interval PLS

Journal of Infrared, Millimeter, and Terahertz Waves - Terahertz radiation has many unique characteristics that make it useful for noninvasive mail inspection. While qualitative analysis of mail...     

液相色谱-串联质谱法测定畜禽肌肉和表皮组织中松香酸、脱氢松香酸和胡椒酸

目的 建立了畜禽肌肉和表皮组织中松香酸、脱氢松香酸和胡椒酸的液相色谱-四极杆/串联质谱(LC-MS/MS)的检测方法。方法 均质样品中加入乙腈和水分别提取目标物,经涡旋分散、震荡提取、离心和固相萃取柱净化。提取液以乙酸铵-甲醇为流动相梯度洗脱C18色谱柱分离,5 mmol的乙酸铵和甲醇为流动相进行梯度洗脱,三重四级杆质谱ESI+/ESI-切换模式检测,以特征离子峰和保留时间定性,定量离子峰面积定量。结果 松香酸、脱氢松香酸的测定低限为5.0 μg/kg、胡椒酸20.0 μg/kg,线性范围分别为5.0~200.0 μg/kg和20.0~500.0 μg/kg,相关系数(r)在0.999以上。分别添加定量限1、2、4倍的浓度验证加标回收率,三个浓度水平的回收率为68.5% ~ 107.6%,相对标准偏差(RSD)为6.8%~14.2%(n=6)。结论 该方法快速、准确、灵敏,适用于监管部门对市售畜禽食品中工业松香残留的检测。     

环戊二烯类有机氯农药单克隆抗体的制备及鉴定

目的制备并鉴定环戊二烯类有机氯农药单克隆抗体。方法以环戊二烯类农药的特征部分为基础设计合成半抗原4-(4,5,6,7,8,8-六氯-3a,4,7,7a-四氢-4,7-亚甲基-1H-聚-1-氧)4-丁酮酸(CCD),并通过活泼酯法将其与载体蛋白BSA、OVA分别偶联制备免疫抗原CCD-BSA和包被抗原CCD-OVA;再经过动物免疫、细胞融合,筛选、克隆,得到1株能稳定分泌环戊二烯类农药抗体的单克隆细胞株。细胞株经扩大培养后,注射小鼠体内产生腹水,并将其用辛酸-硫酸铵和protein A柱子纯化出单克隆抗体。结果 用间接ELISA方法测定其效价为2.5×104,亲和力Ka为6.7×1010L/mol;以β-硫丹为竞争物,采用间接竞争ELISA法建立标准曲线,测得其IC50为16.2 ng/m L,LOD为2.1 ng/m L,定量检测线性范围为4.7~117.5 ng/m L,与其他5种结构类似物的交叉反应率高于10%。结论 本研究成功获得了抗环戊二烯类农药单克隆抗体,该抗体可实现果蔬中环戊二烯类农药的多残留快速检测。     

一种高效率E-1 / F 类GaN HEMT 射频功率放大器

使用GaN HEMT 功率器件,设计了一款5G 低频段的高效率E-1 / F 类射频功率放大器。为降低晶体管寄生参数及高次谐波对逆E 类(E-1 )功放开关特性和输出性能的不良影响,将具有寄生参数补偿的逆F 类(F-1 )谐波控制网络引入逆E 类功放输出匹配电路中,实现了对二次谐波和三次谐波分别进行开路和短路处理,从而获得逆E 类功放要求的良好开关特性。同时,得益于逆F 类功放优良的谐波控制效果,改善了功放漏极电压和电流波形,大大降低其漏极峰值电压和电流,进而提升了功放的输出性能。实测结果表明,该功放在3. 3 ~ 3. 6 GHz 的300MHz 有效工作带宽内的功率附加效率为59. 1% ~ 71. 4%,最大漏极效率高达75. 6%,输出功率在40. 2 ~ 41. 5dBm之间,增益平坦度在依1dB 以内。最后利用20 MHz 带宽的单载波LTE 信号作为测试信号,基于广义记忆多项式数字预失真器对该功放进行线性化后,功放输出的邻信道功率比改善了近15 dB。     

Concentrations of arsenic in urine of the general population in Sweden

The concentration of the sum of the metabolites of inorganic arsenic (inorganic arsenic, methylarsonic acid and dimethylarsinic acid) as well as the concentration of organic arsenic compounds, mainly in the form of arsenobetaine, in the urine of human subjects from two cities in Sweden have been studied. The median concentration of metabolites of inorganic arsenic was ∼8 μg As/g creatinine, independent of place of residence, sex, smoking and consumption of beer and wine. However, subjects who frequently ate flatfish and crustacea had somewhat higher (1.5 times) concentrations than those who very seldom ate such food. Flatfish, mainly in the form of plaice, and crustacea were found to be the main source of organic arsenic compounds. Subjects eating this type of seafood more than once a week had ∼ 40 μg organic As/g creatinine (median value), compared with about 12 μg organic As/g creatinine in subjects who very seldom ate it. Other types of seafish or freshwater fish did not give rise to elevated concentrations of arsenic in the urine. The total range of organic arsenic compounds in urine was < 1 to 525 μg As/g creatinine.     

Review of the current methods of analytical traceability allowing determination of the origin of foodstuffs

Modern analytical techniques, in particular molecular biology techniques, can determine the plant or animal species present in a foodstuff. It is actually very difficult to determine the geographical origin of a food. The new European regulation 178/2002, applicable on January 1st, 2005 imposes this requirement for the traceability of food. This article gives a progress report on the physicochemical and microbiological analytical techniques available which make it possible to determine the origin of a food with some precision.     

Occurrence of four mycotoxins in cereal and oil products in Yangtze Delta region of China and their food safety risks

A total of 76 cereal and oil products collected from Yangtze Delta region of China were analyzed for occurrences of aflatoxins (AFs), aflatoxin B₁ (AFB₁), ochratoxin A (OTA), deoxynivalenol (DON) and zearalenone (ZEN). The mycotoxins were determined by the standard detection procedures using immunoaffinity column clean-up coupled with fluorometer (or HPLC-UV). ZEN was the most prevalent toxin, with the incidence of 27.6% (range = 10.0–440.0 μg kg⁻¹), and 9.2% of the evaluated samples were contaminated with a concentration higher than that of the legislation limit of China (60 μg kg⁻¹). AFs and AFB₁ were detected in 14.5% of the samples analyzed, the concentrations ranging 1.1–35.0 μg kg⁻¹ for AFs, and 1.0–32.2 μg kg⁻¹ for AFB₁; 4.0% of the samples had the concentrations of AFs and AFB₁ higher than that of the corresponding legislation limits of China (5.0, 10.0 and 20.0 μg kg⁻¹ for different products). OTA was detected in 14.5% of the cereal and oil products collected; the concentrations ranged 0.51–16.2 μg kg⁻¹. Only 2 samples showed OTA levels higher than that of the legislation limit of China (5.0 μg kg⁻¹). DON was detected in 7.9% of the samples; the concentrations ranged 100–700 μg kg⁻¹, and none of the samples showed DON concentration higher than that of the legislation limit of China (1.0 mg kg⁻¹). A total of 15.8% cereal and oil products were contaminated with at least two mycotoxins (multiple contaminations with different combinations including AFs-ZEN, AFs-OTA-ZEN, OTA-ZEN, ZEN-DON, OTA-ZEN-DON). The dietary exposure assessment results indicated that AFs (AFB₁), OTA, DON and ZEN from cereal-based products represented a series health risk to both adults and children in Yangtze Delta region of China. This is the first report of safety evaluation associated with major mycotoxins for the area.     

静电场轨道阱质谱分析技术在食品分析中的应用进展

静电场轨道阱质谱技术以其优越的高分辨率和高精确质量数的特性,可实现目标物的同分异构体和结构类似物的鉴定以及未知物的筛查和确证,近年来在生命科学、环境污染以及食品检测领域的应用逐渐增多。本文简要介绍了静电场轨道阱质谱及其联用技术的发展,系统地综述了该项技术近年来在食品分析领域中的应用进展。