海鱼中5种形态有害元素在不同烹调方式下的加工系数研究

目的 研究我国广东省主要海产鱼类在不同典型烹调加工方式下5种有害元素的加工系数,为提升我国食品安全风险评估结果的精确性提供评估参数。方法 基于广东省2个沿海地区居民常消费的19种海产鱼类,随机采样处理后分为清蒸组、油煎组、烘烤组和1个对照组（未烹调组）,检测其总汞、甲基汞、总砷、镉、铅在烹调处理前后浓度的变化,并分别计算每种海鱼中总汞等5种形态有害元素的加工系数。结果 油煎和烘烤处理后海鱼中总汞、甲基汞、总砷、镉的浓度显著高于未烹调组（P<0.05）,而清蒸后海鱼中铅的浓度显著低于未烹调组（P<0.05）。此外不同种类海鱼,相同烹调方式下其有害元素的加工系数存在一定差异,煎和烤的加工方式下海鱼中重金属的加工系数高于清蒸方式。结论 海鱼中总汞、甲基汞、总砷、镉和铅的浓度经过烹调加工后可发生显著变化。风险评估时,应结合评估情形需要,选择合适的加工系数提高风险评估精确度。     

基于模糊相似优先比的纱线条干不匀评价方法

为了准确评价纱线质量,针对目前纱线条干不匀评价指标单一的问题,提出基于模糊相似优先比的纱线条干不匀评价方法;选取变异系数、平均差系数、极差系数3种指标,确定纱线条干不匀标准样本;运用模糊优先比矩阵确定实验样本与标准样本指标的相似程度,通过求和计算得到实验样本与标准样本的总相似度。结果表明：基于模糊相似优先比的纱线条干不匀评价方法,能够有效区分纱线条干不匀等级;对参数指标设置权重系数,可找到与标准样本最优相似的样本。     

乳与乳制品的检测脂肪的扩展不确定度的研究

在确定的函数关系(数学模型中)中,因变量(输出量)随自变量(输入量)的变化规律完全由数学逻辑所确定,自变量到因变量的传递系数(灵敏系数)也可由因变量的标准差和自变量的标准之比所决定.而与自变量的来历(测量的或者给定的)没有关系.本文根据这一基本原理,采用模拟自变法,成功计算了脂肪的扩展不确定度,同时解决了复杂的数学模型中多个输入量到输出量的灵敏系数和输出量的不确定度的计算问题.     

确定部分分式系数的一种简单方法

根据导数的有关理论，找到一种确定部分分式系数的简单方法并给以证明，该方法可有效避免求解方程组所带来的麻烦。     

关于测绘仪器测量不确定度中灵敏系数的研究

灵敏系数是不确定度计算的关键因素,在实际测绘仪器计量检定过程中,输入量的采集方式为不同目标多次测算方式,利用公式计算测量结果,获取输出量。在测量不确定度过程中,基于数学模型的繁杂性,致使对输入、输出量的灵敏系数获取难度加大。文章简要介绍了强行偏导法、方差比例法、传递继承法的计算方法,获取其中的灵敏系数,解决测绘仪器测量不确定度的技术问题。     

圆珠笔用油墨表面张力系数的测量及其不确定度评定

本文根据标准提出的要求,展开了对圆珠笔用油墨的表面张力系数测量的讨论,分析了影响测量不确定度的因素,并采用综合评定法对各个不确定分量进行了评定,给出了测量结果和不确定度的表示方法,最后总结了在测量过程中应注意的事项。     

纺织服装工业用能源及物料的水足迹系数

基于水足迹理论和方法,界定了能源及物料水足迹系数的基本概念;通过重点分析讨论其核算方法,进而对若干纺织服装工业用能源及物料的水足迹系数进行计算与不确定性分析。结果表明,原煤、石油天然气、火电的水足迹系数分别为7.01 m3/t、9.25 m3/t、10.15×10-3m3/kW·h;纸制品、塑料制品、金属制品的水足迹系数分别为10 567.39 m3/Adt、29.27 m3/t、82.85 m3/t;核算结果数据质量等级分总体较高,评价等级良好,核算体系不确定性较低。     

细支卷烟片烟原料的片形需求分析

目的：确定细支卷烟片烟原料的片形需求。方法：应用图像分析技术系统开发了6种片形表征方法,综合片形系数数值与视觉感官判定结果的符合度确定适宜的片形表征方法,以江苏中烟烟叶区域加工中心片烟原料为材料建立片烟片形系数数据库,通过建立模拟切丝模型开展片烟片形需求模拟研究,并制备114个样品进行片烟片形需求试验研究。结果：① 圆度率法可作为适宜的片形表征方法;② 片形系数＜0.35时,碎丝率最大;③ 片形系数＞0.428时,碎丝率基本在2%以下。结论：建议细支卷烟片烟原料的片形系数应大于0.428。     

一种用焦散线确定材料弹性光学系数的新方法

采用内插法将光学各向异性材料的问题转化成准光学各向同性材料的问题,提出了一种用焦散线确定材料弹性光学系数的新方法.以有机玻璃、环氧树脂及聚碳酸脂为例,运用文中所述原理和方法测量了它们的弹性光学系数,并将所得结果与有关资料所给结果进行了比较.     

合成标准不确定度应注意的问题

合成标准不确定度是不确定度评定中的重要环节,对不确定度传播律、输入量相关性、灵敏系数计算等合成标准不确定度应注意的问题进行探讨,并通过实例计算进行分析。     

Applicability and Feasibility of Systematic Review for Performing Evidence-Based Risk Assessment in Food and Feed Safety

Food and feed safety risk assessment uses multi-parameter models to evaluate the likelihood of adverse events associated with exposure to hazards in human health, plant health, animal health, animal welfare, and the environment. Systematic review and meta-analysis are established methods for answering questions in health care, and can be implemented to minimize biases in food and feed safety risk assessment. However, no methodological frameworks exist for refining risk assessment multi-parameter models into questions suitable for systematic review, and use of meta-analysis to estimate all parameters required by a risk model may not be always feasible. This paper describes novel approaches for determining question suitability and for prioritizing questions for systematic review in this area. Risk assessment questions that aim to estimate a parameter are likely to be suitable for systematic review. Such questions can be structured by their “key elements” [e.g., for intervention questions, the population(s), intervention(s), comparator(s), and outcome(s)]. Prioritization of questions to be addressed by systematic review relies on the likely impact and related uncertainty of individual parameters in the risk model. This approach to planning and prioritizing systematic review seems to have useful implications for producing evidence-based food and feed safety risk assessment.     

Characterizing bioaerosol risk from environmental sampling

In the aftermath of a release of microbiological agents, environmental sampling must be conducted to characterize the release sufficiently so that mathematical models can then be used to predict the subsequent dispersion and human health risks. Because both the dose-response and environmental transport of aerosolized microbiological agents are functions of the effective aerodynamic diameter of the particles, environmental assessments should consider not only the total amount of agents but also the size distributions of the aerosolized particles. However, typical surface sampling cannot readily distinguish among different size particles. This study evaluates different approaches to estimating risk from measurements of microorganisms deposited on surfaces after an aerosol release. For various combinations of sampling surfaces, size fractions, HVAC operating conditions, size distributions of release spores, uncertainties in surface measurements, and the accuracy of model predictions are tested in order to assess how much detail can realistically be identified from surface sampling results. The recommended modeling and sampling scheme is one choosing 3, 5, and 10 μm diameter particles as identification targets and taking samples from untracked floor, wall, and the HVAC filter. This scheme provides reasonably accurate, but somewhat conservative, estimates of risk across a range of different scenarios. Performance of the recommended sampling scheme is tested by using data from a large-scale field test as a case study. Sample sizes of 10-25 in each homogeneously mixed environmental compartment are sufficient to develop order of magnitude estimates of risk. Larger sample sizes have little benefit unless uncertainties in sample recoveries can be reduced.     

食源性致病菌污染估计中删失数据分析的研究进展

食源性致病菌污染水平的确定是开展微生物定量风险评估的重要前提,而删失数据的存在易造成对食品中致病菌整体污染水平的估计产生偏差。对检测过程中出现的删失数据进行分析研究已逐渐成为食源性致病菌定量建模工作的重要内容之一。本文对国内外相关研究进行综述,介绍了食源性致病菌污染检测中删失数据的分类,比较了替代法、参数估计法、非参数估计法和多重填补法这4 类常用分析方法,简述了不同特征的致病菌污染检测数据集及相关统计学方法在食源性致病菌污染水平估计中的应用。最后,基于目前食源性致病菌污染水平估计中存在的问题进行探讨,指出降低估计结果不确定性的同时不可忽视检测数据的变异性,并对未来的风险监测、风险评估及风险交流相关研究作出展望。     

高效液相色谱-串联质谱法测定玉米蛋白粉中黄曲霉毒素B1测量不确定度评定

本研究采用GUM法和Top-down法对高效液相-串联质谱法测定玉米蛋白粉中的黄曲霉毒素B1测量不确定度的进行评定。通过比较两种方法的评定过程和评定结果发现,Top-down法在简化评定步骤、保证评定结果可靠性的前提下,能够充分利用实验室检测数据和质量控制数据,能够引入检测人员变动、检测仪器更换等带来的不确定度,是一种客观、高效的不确定度评定方法,为饲料中黄曲霉毒素B1检测数据准确溯源提供依据。     

营养素及相关物质风险评估

营养素物质摄入超过某个上限值时,也能导致不良健康作用,其潜在危害可以通过风险评估描述.但一定量的营养素摄入又是机体正常功能所必需的,新的评估模型应充分考虑营养素物质的特殊性.目前,安全摄入上限(UL)法是国际上广泛接受的营养素物质风险评估方法.对于尚未发现不良作用的营养素物质,FAO/WHO提出了所观察到的最高摄入量(HOI)的概念.对于不存在无风险摄入量水平、风险摄入量水平与生物所需摄入量水平有重叠的营养素物质,亟待在UL法的基础上进一步研究其风险评估方法.本文就上述各类营养素物质的风险评估做一简要综述.     

不同干燥方法对苹果中毒死蜱残留的影响

目的 了解苹果干燥加工过程中毒死蜱残留的降解规律,为苹果干燥产品中农药残留风险的评估提供科学的依据。方法 以红富士苹果为研究对象,采用热风干燥、微波干燥、阳光干燥对苹果片进行了处理,毒死蜱的残留量使用高效液相质谱检测。同时,利用加工因子(PF)建立了毒死蜱的变化模型,分析了干燥过程中水分的扩散系数和苹果片的复水率。结果 毒死蜱在苹果干燥过程中的变化是动态的,它的变化复合动力学模型,微波干燥和阳光干燥对毒死蜱的去除率高于热风干燥。毒死蜱的残留量与干燥条件以及农药的理化性质相关。结论 在苹果的工业生产中,推荐采用微波和阳光干燥来处理苹果,以降低毒死蜱残留带来的食品安全风险。     

Human risk assessment and TEFs

The concept of toxic equivalency factors (TEFs) has been developed to facilitate risk assessment and regulatory control of exposure to complex PCDD, PCDF and PCB mixtures. Recently the European Centre for Environment and Health of the World Health Organization (WHO-ECEH) and the International Programme on Chemical Safety (IPCS) jointly reevaluated the TEFs of PCDDs, PCDFs and dioxin-like PCBs for mammals and derived consensus TEFs for birds and fish (Stockholm, 1997). From a mechanistic point of view it can be concluded that, although the quantitative response will vary depending on the congener involved, the occurrence of a common mechanism (binding to the Ah receptor) legitimates the use of the TEF concept across species. But there also is criticism regarding the TEF concept. Pharmacokinetic differences between species can significantly influence the TEF value, and uncertainties due to additive or nonadditive interactions, to differences in species responsiveness and to differences in the shape of the dose response curve might hamper the derivation of consensus TEF values. In this context it should be noted, however, that using TCDD alone, as the only measure of exposure to dioxin-like PCDDs, PCDFs and PCBs, would severely underestimate the risk from exposure to these compounds. Therefore, it can be concluded that, for pragmatic reasons, the TEF concept remains the most feasible approach for risk assessment purposes, in spite of the uncertainties associated with its use.     

Interspecies metabolism of heterocyclic aromatic amines and the uncertainties in extrapolation of animal toxicity data for human risk assessment

Heterocyclic aromatic amines (HAAs) are potent bacterial mutagens that are formed in cooked meats, tobacco smokes condensate, and diesel exhaust. Many HAAs are carcinogenic in experimental animal models. Because of their wide-spread occurrence in the diet and environment, HAAs may contribute to some common types of human cancers. The extrapolation of animal toxicity data on HAAs to asses human health risk has many uncertainties, which can lead to tenuous risk assessment estimates. Perhaps the most critical and variable parameters in interspecies extrapolation are the effects of dose, species differences in catalytic activities of xenobiotic metabolism enzymes (XMEs), human XME polymorphisms that lead to interindividual differences in carcinogen metabolism and dietary constituents that may either augment or diminish the carcinogenic potency of these genotoxins. The impact of these parameters on the metabolism and toxicological properties of HAAS and uncertainties in extrapolation of animal toxicity data for human risk assessment are presented in this article.     

含不确定参数的时滞非线性系统的鲁棒镇定性

讨论了一类含不确定参数的时滞非线性系统的鲁棒可镇定性。利用代数Ｒｉｃｃａｔｉ方程的正定解以及Ｌｙａｐｕｎｏｖ稳定性的概念，得到了该系统可由状态反馈控制器镇定的充分条件，并给出了控制器的设计。最后通过一个数值例子说明本文中所得到的鲁棒可镇定性判断的有效性。     

Coupling multi-criteria decision analysis, life-cycle assessment, and risk assessment for emerging threats

Emerging environmental threats such as novel chemical compounds, biological agents, and nanomaterials present serious challenges to traditional models of risk analysis and regulatory risk management processes. Even a massive expansion of risk and life-cycle assessment research efforts is unlikely to keep pace with rapid technological change resulting in new and modified materials with changing properties. Therefore, it is essential to have a framework for interpreting available information in the context of high uncertainty and a strategy for prioritizing research efforts to reduce those uncertainties that are most critical. We discuss how integrating the three analytic approaches of risk assessment, life-cycle assessment, and multicriteria decision analysis into a framework permits understanding uncertainty and prioritizes needs for scientific research. Our approach is illustrated with two separate cases: nanomaterials and contaminated sediment remediation.