Dissipation Behavior and Acute Dietary Risk Assessment of Thiamethoxam and Its Metabolite Clothianidin on Spinach

Thiamethoxam and its metabolite clothianidin residues pose a potential threat to human health. This study aims to investigate the residue behavior and acute dietary risk assessment of thiamethoxam and clothianidin on spinach. Thiamethoxam and clothianidin were extracted using a quick, easy, cheap, effective, rugged, safe (QuEChERS) method and analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). At spike levels from 0.01 to 5 mg kg⁻¹, the average recoveries of both analytes were in the range of 94.5–105.5%, with relative standard deviations (RSDs) of 3.8–10.9%. The dissipation behavior of thiamethoxam followed first-order kinetics, with half-lives of ≤1.6 days. Clothianidin appeared readily as a plant metabolite with highest level exhibited during 3 to 5 days after application. Temperature and light may be two main factors for degradation of thiamethoxam. Besides, acute risk assessment of thiamethoxam and clothianidin was evaluated with risk quotients (RQs) <100%, which suggested a low health risk for all consumer groups of Chinese residents.     

企业中行政人员绩效考评问题的思考

利用"价值链分析法"对企业中行政人员的概念进行划分,以明确行政人员和企业其他员工的不同。对企业中行政人员的工作特点绩效考评易出现的工作分析不完善、考核标准不明确、缺乏沟通和反馈等几大问题提出了对行政人员进行科学分析、考核目标和实际工作岗位相结合。考核要公开公正等对策建议。     

Ochratoxin A and 2′R-Ochratoxin A in Selected Foodstuffs and Dietary Risk Assessment

The aim of this study was to estimate the contamination of grain coffee, roasted coffee, instant coffee, and cocoa purchased in local markets with ochratoxin A (OTA) and its isomerization product 2′R-ochratoxin A (2′R-OTA), and to assess risk of dietary exposure to the mycotoxins. OTA and 2′R-OTA content was determined using the HPLC chromatography with immunoaffinity columns dedicated to OTA. OTA levels found in all the tested samples were below the maximum limits specified in the European Commission Regulation EC 1881/2006. Average OTA concentrations calculated for positive samples of grain coffee/roasted coffee/instant coffee/cocoa were 0.94/0.79/3.00/0.95 µg/kg, with the concentration ranges: 0.57–1.97/0.44–2.29/0.40–5.15/0.48–1.97 µg/kg, respectively. Average 2′R-OTA concentrations calculated for positive samples of roasted coffee/instant coffee were 0.90/1.48 µg/kg, with concentration ranges: 0.40–1.26/1.00–2.12 µg/kg, respectively. In turn, diastereomer was not found in any of the tested cocoa samples. Daily intake of both mycotoxins with coffee/cocoa would be below the TDI value even if the consumed coffee/cocoa were contaminated with OTA/2′R-OTA at the highest levels found in this study. Up to now only a few papers on both OTA and 2′R-OTA in roasted food products are available in the literature, and this is the first study in Poland.     

基于GIS的北京市重点地区电磁辐射污染研究

北京市在奥运行动规划中,明确将电磁辐射作为环境治理的重点.在野外数据采集的基础上,运用地理信息系统(GIS)技术,对北京市重点地区(重点居民区、文物保护区、风景旅游区、奥运场馆区)环境的电磁辐射水平进行了分析与评价.结果表明,所调查的4个地区,从总体上看电磁辐射水平都不高,与国家对公众照射的标准(GB8702-88)比较,均在其规定安全限值范围内.     

模糊聚类法在水质评价中的应用--以贵州三岔河某监测断面为例

本文将模糊聚类水质评价方法应用于贵州三岔河某段面的水质评价.结果表明,该方法分辨率高,计算简单,易于应用理解,充分考虑了评价过程的整体性和单个因子的重要性.用该方法进行水质评价比较接近实际.     

基于模糊综合评判的大学数学考核方式改革

独立高校数学课程的开设旨在让学生掌握数学知识的基础上,提高数学应用能力.然而现行的考核方式存在重考试结果,轻学习过程等问题.从传统考核方式入手,指出其不足之处,基于模糊综合评判法建立新型评价体系和数学模型,通过试点运行验证了新的考核方式的可行性、客观性、合理性和科学性.     

非支配解集的质量评价方法

多目标演化算法的目的是获得逼近Pareto最优前沿的分布均匀的非支配解集合,非支配解集的质量是多目标演化算法研究的重要领域.本文对目前提出的非支配解集的质量评价方法进行分类比较,为算法的整体性能评价和算法的性能比较提供了参考依据.     

公路网规划的累积影响评价

分析了公路网规划的累积影响评价的程序和要点,包括评价目的、评价范围、评价要素和评价程序,提出了适合公路网累积影响评价的方法,并对各方法在累积影响中适用性做了初步地探讨.     

基于F&EI的新兴有机材料生产过程风险分析

新兴民营企业在运营流程中采取行政安全一手抓的管理模式,在新型有机材料生产和加工的过程中出现诸多新的安全问题.为规避此类问题带来的事故风险,以浙江某新兴材料企业为例,通过实地调研、定性分析和定量评估相结合的方法,对其物料、工艺、设备及维护过程中的危险源及有害因素进行风险分析.基于现场勘察获得引起生产加工过程中危险物质泄漏...     

有机化学实验教学改革初探

有机化学实验教学是有机化学教育的重要组成部分,要培养高素质的人才,实验教学改革势在必行.本文结合本校的实际情况就改善实验条件、改革有机化学实验教学方法、优化实验教学内容和考核方法等方面提出了一些建议,以求推进有机化学实验教学改革,获得最佳的实验教学效果.