食品快速检测方法现状及建议

食品安全问题一直是人们关注的问题,并且随着食品安全事件的频发而越来越受到人们的重视。食品种类繁多,人们购买食品时,对于食品包装上的成分和含量的了解不充分,同时,质量监督管理部门对食品安全的监管不到位,都可能间接导致人们的生命健康受到一定的威胁,给我们的健康生活带来不利影响,更可能造成心理层面的伤害。为保障人们的身体健康,免于食品安全问题的威胁,建立和完善食品快速检测方法具有重要意义。文章介绍了快速检测方法的特点,食品安全检测技术国内外的应用现状,快速检测产品的生产现状,食品快速检测技术尚存在的一些问题,展望了在食品流通过程中食品快速检测技术的发展前景,并提出了对食品快速检测技术应用的一些建议。     

110 GHz在片16项误差模型校准件定值方法研究

现有商用集总参数校准件电路模型使用简便,但由于校准件电路模型的不完善、电路中参数在提取过程中采用拟合算法等原因,导致其定值准确度受限.从用于高频串扰修正的16项误差模型校准件设计入手,给出了校准件高精度的定值方法——即通过研制辅助的Multiline TRL校准标准,采用测试加仿真的方式对校准件进行定值,并采用定值文件...     

Methods for Detecting Enterohaemorrhagic Escherichia Coli in Food

Enterohaemorrhagic Escherichia coli (EHEC) serogroup determines worldwide foodborne illnesses and remains one of the major concerns for the population and for the food industry. These strains, indeed, determine gastrointestinal disease varying from diarrhoea to haemorrhagic colitis, haemolytic uraemic syndrome, and thrombotic thrombocytopaenic purpura. Classic detection methods are based on specific enrichment, often coupled with immunomagnetic separation system, specific media, and different immunoassays. Molecular detection methods, based on DNA probes and PCR, are used to detect the virulence genes and the specific genes associated to the serogroups. Most of the research is focused on E. coli O157:H7, for which the validated standard method ISO 16654/2001 is applied. Regarding the methods used for E. coli non-O157, it is interesting to highlight the existence of the draft of the European Committee for Standardization, which in the near future might constitute the first standard for non-O157 EHEC. This paper describes the state-of-the-art laboratory methods and commercial kits for detecting strains of EHEC vehiculated with foods.     

A More Realistic Model of Centralized Automatic Generation Control in Real-time Environment

In this article, a more realistic model of centralized automatic generation control is proposed. Conventional centralized control model does not consider the effect of communication delays between the control center and generating units of the plant. These delays degrade the dynamic performance of automatic generation control or may even lead to unstable system. The proposed model incorporates the effect of these communication delays present in an automatic generation control system. The global controller has been developed for the proposed centralized control model. This global controller requires information of all states of the power system model. The proposed model has been investigated in the real-time environment, done with the help of three personal computers connected in series by Ethernet cables, called the real-time three-personal computer system. The novelty of this is that it is maintenance free, robust, and negligible in cost compared to real-time simulator kits available in the market. In summary, the proposed model of centralized automatic generation control is more realistic, incorporates the effect of communication delays, and investigated in the real-time environment. A novel real-time simulator (real-time three-personal computer system) developed is very cost effective. The results of proposed centralized control model are compared with the conventional centralized control model.     

Commercial test kits and the determination of histamine in traditional (ethnic) fish products-evaluation against an EU accepted HPLC method

Although commercial test kits are generally used and/or evaluated for determining histamine in fresh and canned fish, and fish meal, there is little information on their performance and the application for traditional fish products (TFPs), which generally differ in product properties. In this study, three quantitative (Food EIA, Veratox, Histaquant) and four qualitative (Histasure, Histameter, Transia qualitative and semi-quantitative) commercial histamine test kits were evaluated against HPLC method for detecting histamine in several traditional fish products. Among the quantitative kits, Histamine Food EIA showed the best correlation with HPLC method for TFPs (R² = 0.9132) as well as good recoveries ranging between 89 (±4.11)% and 117 (±1.50)%. Although good recoveries were also observed with Veratox kit, poor correlation was found with HPLC. Poor correlation and low recoveries were also observed with Histaquant. Histasure and Transia tube histamine kits showed good agreement with HPLC results. However, the detection limit for Transia qualitative kit is 100 ppm, and for Histasure and Transia semi-quantitative kits can be set to 50 ppm. Therefore, Histasure and Transia semi-quantitative kits are found more suitable for either HACCP monitoring histamine in seafood processing plants or regulatory purposes according to Food Drug and Administration (FDA) legislation for TFPs. However, Transia semi-quantitative kit should be used in caution for histamine cut off values <50 ppm. This study shows that each test kit can represent different performance for determining histamine in TFPs according to product type, and therefore new commercial test kits should be evaluated against an approved analytical method before applications in future for these types of products.     

Current trends in immunoassay-based kits for pesticide analysis

Detection of pesticides and their metabolites in food and environmental samples in real time is the goal of many industries. Immunoassay technology has several attributes that make it a useful tool for screening purposes (e.g., selectivity, sensitivity, portability, and rapid turnaround time). Approximately 90% of the developed immunoassays for the pesticide residue analysis use the ELISA technique. Commercial kits are tailored to target different analytes, thus eliminating in some cases the need for clean-up steps. The manageability of the immunoassay test kit, together with its accuracy and speed of analysis, allows the rapid determination in situ of many samples simultaneously. This article gives an overview on the applications of the immunokits for pesticide analysis in drinking water and foods, as well as examples of different immunoassay formats commonly used. Special attention is given to sample extraction and clean-up procedures. Application to the determination of common pesticides and their detection limit are summarized. Immunoassay kits offer many practical advantages, and the acceptance of these methods depends on several factors, including the demonstration of quality and validity compared with reference methods. Although the advantages of the technique and their applications to food industry quality control are scarcely referred to in the literature.     

Evaluation of different RNA-extraction kits for sensitive detection of hepatitis A virus in strawberry samples

The efficiency of different commercial RNA extraction kits for the detection of hepatitis A virus (HAV) from seeded strawberry samples was assessed by standard RT-PCR and real time RT-PCR (RT-qPCR). The best results with standard RT-PCR were achieved with Aurum™ Total RNA extraction kit (BioRad), obtaining a detection limit of 5-6.25 pfu/mg of tissue. A slightly lower sensitivity was rendered by the RNeasy^® Plant mini kit (Qiagen) (10-12.5 pfu/mg tissue), while the Total Quick RNA Cells and Tissues kit version mini (Talent) rendered a detection limit of 50-100 pfu/mg of tissue. The other tested commercial kits showed worse detection limits (>500 pfu/mg). With RT-qPCR and ten fold diluted RNA all the kits showed an increase of sensitivity, detecting the kits from Qiagen, Talent and BioRad down to 0.05 pfu/mg of strawberry homogenate. These findings indicate that the use of Aurum™ Total RNA extraction kit, with standard RT-PCR technique or RT-qPCR, can not only be labor and time saving but also helpful to improve the sensitivity for the HAV detection from fruits and to facilitate the standardization of detection methods among laboratories.     

复杂环境下60m高冷却塔的拆除爆破

采用控制爆破技术拆除高大薄壁筒式结构时,爆破切口的形状和大小是决定筒体结构能否按设计顺利倒塌、不发生后坐或偏移现象、保证拆除质量和爆破安全的核心与关键.以薄壁双曲线冷却塔拆除爆破为例,合理选取切口长度、高度等参教,成功地拆除了1座60m钢筋混凝土冷却塔.     

99Tcm放射性药盒中微量亚锡的测定

用紫外-可见分光光度法测定了亚锡亚甲基二膦酸盐冻干品（MDP）、亚锡葡萄糖酸钠冻干品（Glu）、亚锡植酸盐冻干品（Phy）、亚锡二乙三胺五乙酸冻干品（DTPA）4种药盒中微量亚锡离子的含量。络合物在460nm处有特征吸收峰,显色时间为15min,亚锡含量的测定范围选择为5～25μg。该方法对4种药盒的测定具有灵敏性强、方便、快速等特点。     

爆破切割技术在航道清理工程中的应用

介绍了一例运用爆破切割技术对沉船切割解体进行航道清理的相关技术与工艺.论述了水下爆破施工技术要点和施工步骤,并结合施工经验总结了水下爆破施工的施工要点.