食品中金黄色葡萄球菌平板计数不确定度的评定

在金黄色葡萄球菌检测过程中,由于样品中金黄色葡萄球菌计数受到样品制备、溶液稀释、向培养基添加样液、培养时间和操作人员技能等因素的影响,使检测结果离散度较大。实验主要研究采用在同一时间段内,应用同一批次的培养基和试剂,按相同的检测过程,对同一批样品进行检测。根据检测过程和检测结果对不确定度的贡献,探讨金黄色葡萄球菌计数的不确定度评定。     

分光光度法测定水质总氰化物不确定度评定

工业污水中存在着大量的氰化物,若处理不当,则会造成严重的环境污染。为反映总氰化物检测结果的准确性,文章介绍了总氰化物检测原理及测量不确定度的来源,通过运用分光光度法对水质中总氰化物的不确定度进行评定,并对测定结果进行分析。供类似研究参考。     

食品微生物检验中菌落总数测定的注意事项

1菌落总数及测定菌落是指细菌在固体培养基上生长繁殖而形成的能被肉眼识别的生长物,它是由数以万计相同的细菌集合而成。当样品被稀释到一定程度,与培养基混合,在一定培养条件下,每个能够生长繁殖的细菌细胞都可以在平板上形成一个可见的菌落。菌落总数就是指食品检样经过处理     

菌落总数检测胶膜的制备与应用

本文应用胶膜法和平板倾注法,检验省内外14个单位的食品、水、化妆品等10种2445份样品的菌落总数,经符号秩和统计,P>0.05,结果无显著差异,胶膜法操作简便,成本低廉、结果准确、运输和保存方便,对基层检验单位有广泛的应用价值。     

ATP生物荧光法快速检测化妆品中菌落总数的研究

本文从快速检测的必要性出发,介绍了ATP生物荧光法及其原理,并针对某款化妆品通过一系列实验建立了一种快速检测菌落总数的方法。将该方法用于CTFA(美国化妆品香料香精协会,Cosmetic Toiletry and Fragrance Association)实验中,并通过与平板计数法结果进行比对,发现该方法可以有效的运用于样品细菌总数的快速检测。     

食用槟榔中霉菌和酵母的测量不确定度评定

近年来槟榔的食用安全引起了社会的广泛关注,槟榔行业对微生物控制的要求也进一步提高,微生物检测的准确性和可靠性越来越受到重视。然而,目前尚无槟榔微生物的分析报道。本研究建立了槟榔中霉菌和酵母定量检测测量不确定度评定的方法。结果表明,霉菌与酵母的扩展不确定度分别为0.342 4和0.286 4,其中,重复检测引入的不确定度远高于其他因素引入的不确定度。此外,本研究还发现,霉菌和酵母的不确定度评定应该分开进行。     

3M Petrifilm快速菌落总数测试片法与食品中菌落总数检测国标方法（GB 4789.2‒2010）的比较

目的 比较3MTM PetrifilmTM快速菌落总数测试片（RAC）法与食品中菌落总数检测国标方法（GB 4789.2‒2010）检测熟肉样品、人工污染熟肉样品中的菌落总数结果的一致性。方法 分别用两种方法对129份熟肉样品和166份人工污染熟肉样品进行菌落总数项目的检测,并对3MTM PetrifilmTM快速菌落测试片法与国标方法的实验结果进行配对资料t检验、线性回归分析以及对数值差值绝对值（|dlog|）汇总分析。结果 第一部分：两种方法检测熟肉样品、人工污染熟肉样品的菌落总数检测结果t=1.5704、P=0.1188,差异无统计学意义;相关系数R2值分别为0.897、0.964;|dlog|≤0.500所占百分比分别为97.7％、100.0％。第二部分：两种方法检测295份样品,t=1.1336,P=0.2586;相关系数R2=0.992;|dlog|≤0.500的结果百分率为99.0％。结论 在检测熟肉样品、人工污染熟肉样品时,3MTM PetrifilmTM快速菌落总数测试片法与国标方法检测结果的一致性较好。     

气相色谱法测定橄榄中三唑酮残留量的不确定度评定

介绍了气相色谱法测定橄榄中三唑酮残留量的不确定度评定方法。结果表明,测量过程中三唑酮残留量的不确定度主要来源于校准过程、重复性测量和回收率;当橄榄三唑酮含量为0.072 21 mg·kg-1时,扩展不确定度U = 0.005 576 mg·kg-1(k = 2)。     

配方奶粉中维生素C检测方法探讨

本文就配方奶粉中维生素C检测方法进行了探讨,对实验中所要用到的主要仪器及试剂作了详细的介绍,并列举样品预处理和测定两个方面的步骤措施,最后还针对实验所得的结果进行了讨论,以期能为在配方奶粉中更易检测维生素C而提供参考借鉴。     

不同方法检测鸡蛋表面菌落总数的相关性研究

研究了ATP生物荧光检测法与国标法《GB4789.2-2010食品卫生微生物学检验菌落总数测定》检测鸡蛋壳表面细菌总数的相关性。采用ATP生物荧光检测法和国标法对40个混合样品表面细菌总数进行检测,以log CFU/个蛋壳为横坐标(x),以logRLU/个蛋壳为纵坐标(y),分别进行线性、对数、乘幂、指数拟合。结果表明,ATP荧光检测法与国标法检测结果 Pearson相关系数为0.912,线性模型y=0.7306x-1.0041(R2=0.8322)拟合度较高。该试验结果为ATP荧光检测法在鸡蛋壳表面细菌总数快速检测中应用的可行性提供了依据。     

Uncertainty in Multi-Pathway Risk Assessment for Combustion Facilities

Multi-pathway risk assessments (MPRAs) of contaminant emissions to the atmosphere consider both direct exposures, via ambient air, and indirect exposures, via deposition to land and water. MPRAs embody numerous interconnected models and parameters. Concatenation of many multiplicative and incompletely defined assumptions and inputs can result in risk estimates with considerable uncertainties, which are difficult to quantify and elucidate. Here, three MPRA case-studies approach uncertainties in ways that better inform context-specific judgments of risk. In the first case, default values predicted implausibly large impacts; substitution of site-specific data within conservative methods resulted in reasonable and intuitive worst-case estimates. In the second, a simpler, clearly worst-case water quality model sufficed to demonstrate acceptable risks. In the third case, exposures were intentionally and transparently overestimated. Choices made within particular MPRAs depend on availability of data as suitable replacements for default assumptions, regulatory requirements, and thoughtful consideration of the concerns of interested stakeholders. Explicit consideration of the biases inherent in each risk assessment lends greater credibility to the assessment results, and can form the bases for evidence-based decision-making.     

Harmonizing the Incorporation of Uncertainty and Variability Into Risk Assessment: An International Approach

International harmonization of risk assessment approaches affords a number of opportunities and advantages. Overall, harmonization will lead to more efficient use of resources, but also will lead to better understanding amongst scientists and regulators worldwide. It is with these goals in mind that in 1994 the International Programme on Chemical Safety (IPCS) initiated its Project on the Harmonization of Approaches to the Assessment of Risk from Exposure to Chemicals (Harmonization Project). An ongoing activity under this project addresses uncertainty and variability in risk assessment. The goal of the overall activity is to promote harmonization of risk assessment methodologies for noncancer endpoints. However, given the common links in uncertainty and variability that apply across a range of end-point-specific activities, these links are identified wherever possible. This paper provides an overview of the IPCS Harmonization Project and reviews the activity and future plans related to uncertainty and variability.     

Extrapolation in Risk Assessment: Improving the Quantification of Uncertainty,and Improving Information to Reduce the Uncertainty

Risk assessments inevitably extrapolate from the known to the unknown. The resulting calculation of risk involves two fundamental kinds of uncertainty: uncertainty owing to intrinsically unpredictable (random) components of the future events, and uncertainty owing to imperfect prediction formulas (parameter uncertainty and error in model structure) that are used to predict the component that we think is predictable. Both types of uncertainty weigh heavily both in health and ecological risk assessments. Our first responsibility in conducting risk assessments is to ensure that the reported risks correctly reflect our actual level of uncertainty (of both types). The statistical methods that lend themselves to correct quantification of the uncertainty are also effective for combining different sources of information. One way to reduce uncertainty is to use all the available data. To further sharpen future risk assessments, it is useful to partition the uncertainty between the random component and the component due to parameter uncertainty, so that we can quantify the expected reduction in uncertainty that can be achieved by investing in a given amount of future data. An example is developed to illustrate the potential for use of comparative data, from toxicity testing on other species or other chemicals, to improve the estimates of low-effect concentration in a particular case with sparse case-specific data.     

Treatments of Uncertainty and Variability in Ecological Risk Assessment of Single-Species Populations

The selection of the most appropriate model for an ecological risk assessment depends on the application, the data and resources available, the knowledge base of the assessor, the relevant endpoints, and the extent to which the model deals with uncertainty. Since ecological systems are highly variable and our knowledge of model input parameters is uncertain, it is important that models include treatments of uncertainty and variability, and that results are reported in this light. In this paper we discuss treatments of variation and uncertainty in a variety of population models. In ecological risk assessments, the risk relates to the probability of an adverse event in the context of environmental variation. Uncertainty relates to ignorance about parameter values, e.g., measurement error and systematic error. An assessment of the full distribution of risks, under variability and parameter uncertainty, will give the most comprehensive and flexible endpoint. In this paper we present the rationale behind probabilistic risk assessment, identify the sources of uncertainty relevant for risk assessment and provide an overview of a range of population models. While all of the models reviewed have some utility in ecology, some have more comprehensive treatments of uncertainty than others. We identify the models that allow probabilistic assessments and sensitivity analyses, and we offer recommendations for further developments that aim towards more comprehensive and reliable ecological risk assessments for populations.     

Stochastic and Subjective Uncertainty in the Assessment of Radiation Exposure at the Waste Isolation Pilot Plant

The Waste Isolation Pilot Plant (WIPP) is under development by the U.S. Department of Energy as a geologic (i.e., deep underground) disposal facility for transuranic waste. An analysis is presented of possible radiation exposures associated with inadvertent drilling intrusions through the WIPP using future drilling rates obtained in accordance with requirements specified by the U.S. Environmental Protection Agency (EPA) in 40 CFR 194, Subpart B. The analysis attempts to maintain a separation between stochastic (i.e., aleatory) and subjective (i.e., epistemic) uncertainty as implied in the EPA regulations 40 CFR 191, Subpart B, and 40 CFR 194. The results of the analysis are presented as distributions of complementary cumulative distribution functions (CCDFs) for radiation exposure to oil field workers, where the individual CCDFs arise from stochastic uncertainty (i.e., many possible patterns of drill ing intrusions are possible over the 10,000?yr period specified in 40 CFR 191, Subpart B) and the distributions of CCDFs arise from subjective uncertainty (i.e., many inputs to the analysis have fixed, but poorly known, values). The projected radiation exposures during the 10,000?yr period following decommissioning of the WIPP in the year 2033 were found to be small (typically less than 0.001 person-Sv), with the dominant exposure pathway being the incidental ingestion of contaminated dirt by drilling crew members.     

中药超微粉对早期断奶仔猪白细胞分类和抗氧化功能的影响

为了研制高效、安全、无污染的抗生素替代物作为断奶仔猪饲料添加剂,本研究观察了中药超微粉对21日龄断奶仔猪外周血白细胞分类和血清抗氧化功能的影响。结果表明,D7时,超微粉组MDA含量显著小于抗生素组和对照组(P<0.05),NO含量显著小于对照组(P<0.05);D14时,超微粉组NO含量显著大于抗生素组和对照组(P<0.05);D28时,超微粉组NEU计数和百分率及MON百分率均显著小于、LYM百分率显著大于对照组(P<0.05),N/L小于抗生素组(P>0.05)、显著小于对照组(P<0.05),SOD活性显著大于抗生素组和对照组(P<0.05),GSH活性显著大于对照组(P<0.05)。上述指标的变化,与该超微粉对断奶仔猪的防病促生长作用有一定联系。     

Identifying Uncertainty in Environmental Risk Assessments: The Development of a Novel Typology and Its Implications for Risk Characterization

Environmental risk analysts need to draw from a clear typology of uncertainties when qualifying risk estimates and/or significance statements about risk. However, categorizations of uncertainty within existing typologies are largely overlapping, contradictory, and subjective, and many typologies are not designed with environmental risk assessments (ERAs) in mind. In an attempt to rectify these issues, this research provides a new categorization of uncertainties based, for the first time, on the appraisal of a large subset of ERAs, namely 171 peer-reviewed environmental weight-of-evidence assessments. Using this dataset, a defensible typology consisting of seven types of uncertainty (data, language, system, extrapolation, variability, model, and decision) and 20 related sub-types is developed. Relationships between uncertainties and the techniques used to manage them are also identified and statistically evaluated. A highly preferred uncertainty management option is to take no action when faced with uncertainty, although where techniques are applied they are commensurate with the uncertainty in question. Key observations are applied in the form of guidance for dealing with uncertainty, demonstrated through ERAs of genetically modified higher plants in the European Union. The presented typology and accompanying guidance will have positive implications for the identification, prioritization, and management of uncertainty during risk characterization.     

Uncertainty Analysis and Toxicity Classification in Life-Cycle Assessment Using the Case-study of Gas Purification Systems

This comprehensive thesis structures the decision-making process for making a choice of the most adequate gas purification system (GasPS). Various gas purification technologies (biofilter, activated carbon filter, catalytic oxidation, thermo-reactor) have been evaluated based on an industrial case-study for waste gas streams. The ecological performance was quantified using the life-cycle impact assessment methods Eco-Indicator 95 and Swiss Ecopoints (environmental scarcities). Both life-cycle impact assessment methods have been improved by a new classification method for volatile organic compounds (VOCs) which considers the environmental fate and exposure as well as the toxicity of these compounds. For life-cycle assessment, a detailed quantitative uncertainty analysis was carried out using Monte Carlo simulation. Based on the uncertainty analysis, developing statements about the significance of the results and of relative differences between various GasPS alternatives has been possible. The eco-efficiency of the investigated GasPSs was finally characterised based on four indicators: Net Ecological Benefit (NEB_N), Ecological Yield Efficiency (lgEYE), Net Present Value (NPV), and Ecological-Economic Efficiency (EEE).     

Gold Immunochromatography Assay for the Rapid Detection of Spiramycin in Milk and Beef Samples Based on a Monoclonal Antibody

Spiramycin (SP) residues in food do harm to human health. It is necessary to establish rapid detection method for SP. In this work, a monoclonal antibody (mAb)‐based gold immunochromatography assay (GICA) is developed for the rapid detection of SP. Under optimum conditions, the half‐maximal inhibitory concentration of SP‐mAb is 0.43 ng mL^–1. The subtype of SP‐mAb is IgG2b. This antibody has no cross‐reactivity with other analogues and has high affinity (4.52 × 10¹⁰ L mol^–1). Qualitative results can be visualized with the naked eye, with a visual detection limit of 1.0 ng mL^–1 and cut‐off value of 10 ng mL^–1. A hand‐held strip scanner is used for the quantitative analysis, with LOD 0.43 ng mL^–1 in assay buffer. The recoveries of SP ranged from 72.3% to 112% in milk and 98.5% to 115% in beef, with variable coefficient ranging from 9.4% to 11.7% in milk and 8.14% to 15.4% in beef. Besides, the proposed GICA method for SP is confirmed by LC–MS/MS in SP‐spiked milk and beef samples. Overall, the developed GICA can be a useful tool for SP residues on‐site screening in milk and beef samples.