食品用洗涤剂中甲基异噻唑啉酮类防腐剂检测的必要性

甲基异噻唑啉酮类防腐剂是一类具有高效、广谱的杀菌和抑菌性能的防腐剂,广泛应用于各类防腐领域,但该类防腐剂能否用于食品相关产品还有待研究。文章主要介绍了甲基氯异噻唑啉酮与甲基异噻唑啉酮的混合物和甲基异噻唑啉酮两类防腐剂,以及近年各国对化妆品中甲基异噻唑啉酮类防腐剂的限量要求。从调查数据看,市场上大多食品用洗涤剂都含有甲基异噻唑啉酮类防腐剂,有的含量甚至超过化妆品安全技术规范中最大允许浓度,对人体健康可能会产生较大威胁。因此,有必要对食品用洗涤剂中甲基异噻唑啉酮类防腐剂进行检测,并建议在食品用洗涤剂国家标准中列入对甲基异噻唑啉酮类防腐剂的限量。     

基于单片机和GM8125的多路串口收发器设计

介绍了串口扩展芯片GM8125的特性,设计了基于该芯片和8051单片机的多路串口收发器,程序算法及硬件电路实现了多达4台子设备(电子天平)到主设备(打印机)数据标号传输,并有效地解决了GM8125芯片多路并行工作时的出现的乱码和数据混乱的问题。系统使用方便,实时性好,扩展方便,取得了良好的实际应用效果。     

任意阶PDE降噪特性分析

通过对分数阶微积分原理的研究,提出了任意阶偏微分方程(partial differential equations,简称PDE)降噪的统一模型,实现了基于任意阶PDE降噪的数值化方法,并分析了任意阶PDE降噪特性。该数值化方法能够快速实现信号降噪,耗时少。通过仿真实验,分析了PDE降噪性能的影响因素,与其他去噪方法进行了对比分析,并对现场实测信号进行了降噪分析。结果表明,PDE数值求解降噪方法性能优良,算法简单。     

质量法压缩天然气加气机在线检测装置

研制了一套基于质量法的压缩天然气加气机在线检测装置,系统集成了数据采集和自动控制系统。利用计算机控制工作流程,实时采集瞬时流量、累计流量、密度、温度等信号,实现在线检测。对系统的不确定度分量进行了分析,给出了测量结果的不确定度。基于使用该标准装置进行检测的经验,给出了保证检测结果准确可靠应采取的一些措施。     

高效液相色谱法同时检测调味品中的苏丹红和对位红

建立了调味品中苏丹红Ⅰ、Ⅱ、Ⅲ、Ⅳ和对位红的同时检测方法。样品用正己烷提取，提取液用氧化铝层析柱净化。采用Zorbax SB C18柱分离，以95％甲醇为流动相，流速1mL／min，检测波长505nm。上述5种色素组分在其质量浓度为0．16～2．56mg／L时有良好的线性关系，方法的检测限为17～69μg／kg；平均加标回收率为85％～125oA，相对标准偏差为2．6％～6．7％。该方法灵敏可靠，适合于调味品中苏丹红与对位红的同时检测。     

Direct determination of free tryptophan contents in soy sauces and its application as an index of soy sauce adulteration

A simple and rapid HPLC method using UV detector for determination of tryptophan (Trp) contents in pure fermented soy sauces, acid-HVP, and commercial soy sauces was developed. The method requires only simple sample pretreatment. The limit of detection (LOD) is estimated at 1 mg/L (signal-to-noise ratio of 3), and the recovery yields ranged from 92% to 108%. The analysis showed that Trp in all of the analysed acid-HVP samples was not detected and there was obvious detection of Trp (ranged from 136.4 to 261.8 mg/L) in all of the analysed fermented soy sauce samples. The observations suggest that Trp is a practical index of pure fermented soy sauce. The absence of Trp contents or lower level of Trp contents than that in pure fermented soy sauces suggests the soy sauces are not pure fermented soy sauces or presence of soy sauce adulteration. Simultaneous determination of levulinic acid (LV) in samples may be a good help in making assessment of soy sauce adulteration with acid-HVP.     

Application of the standard addition method for the determination of acrylamide in heat-processed starchy foods by gas chromatography with electron capture detector

A gas chromatography electron capture detector (GC-ECD) using the standard addition method was developed for the determination of acrylamide in heat-processed foods. The method entails extraction of acrylamide with water, filtration, defatting with n-hexane, derivatization with hydrobromic acid and saturated bromine-water, and liquid–liquid extraction with ethyl acetate. The sample pretreatment required no SPE clean-up and concentration steps prior to injection. The final extract was analyzed by GC-ECD. The chromatographic analysis was performed on polar columns, e.g. Supelcowax-10 capillary column, and good retention and peak response of the analyte were achieved under the optimal conditions. The qualification of the analyte was by identifying the peak with same retention time as standard compound 2,3-DBPA and confirmed by GC–MS. GC–MS analysis confirmed that 2,3-DBPA was converted to 2-BPA nearly completely on the polar capillary column, whether or not treated with triethylamine. A four-point standard addition protocol was used to quantify acrylamide in food samples. The limit of detection (LOD) was estimated to be 0.6 μg/kg on the basis of ECD technique. Validation and quantification results demonstrated that the method should be regarded as a low-cost, convenient, and reliable alternative for conventional investigation of acrylamide.     

Present state of corrosion inhibitors in Japan

In this report, the utilization, research and development of corrosion inhibitors in Japan and the action mechanism of corrosion inhibitors are explained, and their effects and future utilization are also described. In Japan, corrosion inhibitor was commercialized in the 1970s, and the use of these showed the rapid elongation as a countermeasure of the use of sea sand as an aggregate for the period 1975–1977 and the use of corrosion inhibitors decreased after 1979 because of the regulation for the total amounts of chloride in concrete in the standards. Then, amounts of concretes with corrosion inhibitors decreased in 1990s. However, in the civil engineering and construction industry fields, they seem to have to deal with the problem of increase of chloride content in concrete by the deregulation and the utilization of various industrial waste materials. We should consider the utilization of corrosion inhibitor from the new viewpoint.     

惯性导航设备升沉数据测试系统研究

研制了一套基于STM32单片机与单轴摇摆台的测试系统,利用固定圆心、固定半径条件下的圆内三角形关系,通过拉线传感器采集单轴摇摆台复合运动中的升沉数据;同时,对惯性导航设备输出的升沉数据进行采集与处理。对测试系统输出的升沉数据进行了验证,实验结果表明:该测试系统的测试数据准确合理,可实现对惯性导航设备升沉参数的动态测试,弥补了现有同类测试系统的结构复杂、量程小等不足。     

Optimal Design and Economic Evaluation of Dividing‐Wall Columns

In an effort to reduce costs, a systematic optimization approach is proposed to address the energy consumption of dividing‐wall columns (DWCs). This iterative optimization procedure begins by minimizing the overall heat duty using an innovative objective function within a constrained design space. A sensitivity analysis is then carried out on the manipulated variables to obtain their optimal ranges. Optimal operating parameters are obtained through the evaluation of the total annualized cost (TAC). For the separation process of benzene/toluene/o‐xylene, the optimal DWC flow sheet exhibits a significant decrease in TAC when compared to conventional flow sheet optimum designs. The applied optimization method and sensitivity analysis have proven to produce results at the global optimum. This method is both practical and easily applied to other systems, even to systems with more than three components.