共振瑞利散射法铬蓝黑R探针测定牛血清白蛋白

本文研究了在pH4.1的B-R缓冲溶液中,SDS胶束存在下,铬蓝黑R(EBR)-牛血清白蛋白(BSA)体系的共振瑞利散射光谱,EBR和BSA的共振瑞利散射强度(RRS)十分微弱。当两者形成复合物时能使RRS信号急剧增强,其最大散射峰为393nm。EBR测定BSA的线性范围是0～2.0μg·mL-1,线性回归方程为ΔI=-35.33+209.94ρ(μg/mL),该方法的检出限为6.19×10-8g·mL-1,该方法用于奶粉中牛血清白蛋白的测定,结果令人满意。     

应用原子荧光光谱仪测定大鼠器官中的镉

采用原子荧光法测定大鼠器官中镉的含量(湿重),相关系数是0.9998,线性范围在0.1～1.0μg/L,相对标准偏差在1.73%～2.29%之间,实验结果表明该方法具有稳定、灵敏和快速的特点。     

硅合金中硅含量的测定

文章研究了分光光度法测定锰硅合金中硅含量的方法。在硝酸和氢氟酸溶液中硅以正硅酸存在,加入钼酸铵形成硅钼杂多酸显色,在660nm波长处测吸光度。方法的线性范围为:0.1～0.4μg/mL(指含硅量),精密度(RSD)为0.65%,加标回收率为102%,具有一定的价值。     

石墨炉原子吸收法测定化探样品中的微量镉

地质化探样品经高氯酸,氢氟酸,王水溶解后,1∶1盐酸提取,KI-MIBK萃取分离富集,选择最佳的仪器工作条件,利用石墨炉原子吸收法测定化探样品中的微量镉的含量.其检出限为0.045μg.g-1,精密度为(RSD , n=6)≤5.5%,标准物质分析结果与推荐值一致     

2017-2018年福建沿海地区大气颗粒物污染对人群健康的影响

选取2017-2018年福建沿海26个代表性县区监测点,运用泊松广义相加模型时间序列方法分析不同疾病别的超额死亡风险及置信区间95%CI。结果表明,2017-2018年PM_(10)和PM_(2.5)浓度(lag01)每升高10μg/m~3,研究区域人群非意外总死亡风险分别增加1.07%(95%CI:0.60%,1.54%)、1.71%(95%CI:0.93%,2.49%),心脑血管疾病死亡风险分别增加1.17%(95%CI:0.46%,1.88%)、1.92%(95%CI:0.75%,3.08%),区域之间存在效应异质性;研究区域夏季风险最高,其次为冬季,春秋季统计学关联性较弱;PM_(2.5)对呼吸系统疾病效应在调整PM_(2.5-10)的影响后失去统计学意义。2017-2018年大气颗粒物暴露与福建沿海人群非意外总死亡和心脑血管疾病死亡风险增加具有统计学意义,非意外总死亡和心脑血管疾病死亡效应分别以5日平均滞后(lag04)和4日平均滞后(lag03)最大。     

硅合金中硅含量的测定

文章研究了分光光度法测定锰硅合金中硅含量的方法.在硝酸和氢氟酸溶液中硅以正硅酸存在,加入钼酸铵形成硅钼杂多酸显色,在660nm波长处测吸光度.方法的线性范围为:0.1～0.4 μg/mL(指含硅量),精密度(RSD)为0.65%,加标回收率为102%,具有一定的价值.     

气相色谱法测定水中丙烯酰胺

通过KBr-KBrO3在强酸中生成的溴与丙烯酰胺的烯键加成,将丙烯酰胺反应成稳定的α,β-二溴丙酰胺,通过气相色谱法测出α,β-二溴丙酰胺(2,3-DBPA)的浓度,再算出丙烯酰胺在水中的浓度。结果:进行7次平行精度试验,相对标准偏差为3.66%,检出限为0.0069μg/L。通过三次实验,加标回收率为85.54%⁹2.37%,相对标准偏差为3.84%。本气相色谱法具有简便、快速、准确、检出限低等优点,适合水中丙烯酰胺的分析测定。     

气相色谱法测定蔬菜中氟虫腈和丁烯氟虫腈

该文提出了固相萃取-气相色谱法快速检测蔬菜中氟虫腈和丁烯氟虫腈多残留的分析方法。样品用乙腈水溶液均质提取,经盐析作用分离出乙腈层,经Carb柱净化后用GC-u ECD检测分析,采用外标法定量。方法的检出限(S/N=3)为0.4⁰.8μg/kg,在加标水平为10μg/kg时,平均回收率为115%0.8μg/kg,在加标水平为10μg/kg时,平均回收率为115%¹17%,相对标准偏差为5.4%117%,相对标准偏差为5.4%⁵.5%;在加标水平为20μg/kg时,平均回收率为102%5.5%;在加标水平为20μg/kg时,平均回收率为102%¹08%,相对标准偏差为4.2%108%,相对标准偏差为4.2%⁴.6%。     

三重四级杆液质联用法快速测定地表水和饮用水中微囊藻毒素LR

该文采用三重四级杆液质联用法快速测定地表水和饮用水中微囊藻毒素,水样经0.20μm的有机滤膜过滤后,1:1加入甲醇混合后直接进样测定。该方法相比于液相色谱法,省去了繁琐的固相萃取工作,通过选择离子反应监测(MRM),实现更加准确的定性定量,避免假阳性的结果,方法灵敏度高、简便、高效。方法检出限度为0.05μg/L,加标回收率在72.0%~95.2%之间,结果令人满意。     

209例肺癌患者全身骨显像临床分析

目的:探讨骨全身显像结果与不同临床分期及病理类型肺癌患者的关系。方法:对209例经病理证实的肺癌患者行常规全身骨显像。其结果与患者临床分期及病理类对照。结果:Ⅰ-Ⅱ期患者骨转移发生率0例(0%),Ⅲ期患者8例(9.5%),IV期患者105例(89.7%),总转移率为54.1%。其中鳞状细胞癌(34/92),腺癌(33/60),大细胞癌(26/33),小细胞癌(21/34);多发转移(3处以上)63例,少发转移(2-3处)37例,单发13例。结论:Ⅲ-Ⅳ期肺癌患者应实施常规骨显像,以免漏诊骨转移。     

An Evolutionary Algorithm for Sequencing Production on a Paced Assembly Line

A new sequencing method for mixed‐model assembly lines is developed and tested. This method, called the Evolutionary Production Sequencer (EPS) is designed to maximize production on an assembly line. The performance of EPS is evaluated using three measures: minimum cycle time necessary to achieve 100% completion without rework, percent of items completed without rework for a given cycle time, and sequence “smoothness.” The first two of these measures are based on a simulated production system. Characteristics of the system, such as assembly line station length, assembly time and cycle time, are varied to better gauge the performance of EPS. More fundamental variation is studied by modeling two production systems. In one set of tests, the system consists of an assembly line in isolation (i.e., a single‐level system). In another set of tests, the production system consists of the assembly line and the fabrication system supplying components to the line (i.e., a two‐level system). Sequence smoothness is measured by the mean absolute deviation (MAD) between actual component usage and the ideal usage at each point in the production sequence. The performance of EPS is compared to those of well‐known assembly line sequencing techniques developed by Miltenburg (1989), Okamura and Yamashina (1979), and Yano and Rachamadugu (1991). EPS performed very well under all test conditions when the criterion of success was either minimum cycle time necessary to achieve 100% production without rework or percent of items completed without rework for a given cycle time. When MAD was the criterion of success, EPS was found inferior to the Miltenburg heuristic but better than the other two production‐oriented techniques.     

Der Einsatz von Tablet-Computern im Coaching

There is meanwhile quite a large number of programmes (apps) available for tablet computers which can be used during Coaching. They can be used by coaches for preparation and consolidation, during coaching sessions and by clients themselves in times when they are not in contact with their coaches. This article presents application fields and discusses frame conditions for the use of tablets in Coaching.     

Uncertainty and Sensitivity Analysis in Assessment of the Thyroid Cancer Risk Related to Chernobyl Fallout in Eastern France

The increase in the thyroid cancer incidence in France observed over the last 20 years has raised public concern about its association with the 1986 nuclear power plant accident at Chernobyl. At the request of French authorities, a first study sought to quantify the possible risk of thyroid cancer associated with the Chernobyl fallout in France. This study suffered from two limitations. The first involved the lack of knowledge of spontaneous thyroid cancer incidence rates (in the absence of exposure), which was especially necessary to take their trends into account for projections over time; the second was the failure to consider the uncertainties. The aim of this article is to enhance the initial thyroid cancer risk assessment for the period 1991-2007 in the area of France most exposed to the fallout (i.e., eastern France) and thereby mitigate these limitations. We consider the changes over time in the incidence of spontaneous thyroid cancer and conduct both uncertainty and sensitivity analyses. The number of spontaneous thyroid cancers was estimated from French cancer registries on the basis of two scenarios: one with a constant incidence, the other using the trend observed. Thyroid doses were estimated from all available data about contamination in France from Chernobyl fallout. Results from a 1995 pooled analysis published by Ron et al. were used to determine the dose-response relation. Depending on the scenario, the number of spontaneous thyroid cancer cases ranges from 894 (90% CI: 869-920) to 1,716 (90% CI: 1,691-1,741). The number of excess thyroid cancer cases predicted ranges from 5 (90% UI: 1-15) to 63 (90% UI: 12-180). All of the assumptions underlying the thyroid cancer risk assessment are discussed.     

Effects of Hourly,Low-Incentive,and High-Incentive Pay on Simulated Work Productivity: Initial Findings With a New Laboratory Method

The failures of previous studies to demonstrate productivity differences across different percentages of incentive pay may be partially due to insufficient simulation fidelity. The present study compared the effects of different percentages of incentive pay using a more advanced simulation method. Three payment methods were tested: hourly, low-incentive, and high-incentive (0%, 10%, and 100%) pay. Four participants performed a simulated work task for 30 6-hr sessions. Productivity under the 100% incentive condition was consistently higher than under the 10% condition for all participants. Productivity under the 10% condition was higher than under the 0% condition for two participants. Results suggest that different percentages of incentive pay may in fact produce productivity differences under more realistic simulated work conditions.     

Quantitative Risk Assessment of Haemolytic and Uremic Syndrome Linked to O157:H7 and Non‐O157:H7 Shiga‐Toxin Producing Escherichia coli Strains in Raw Milk Soft Cheeses

Shiga‐toxin producing Escherichia coli (STEC) strains may cause human infections ranging from simple diarrhea to Haemolytic Uremic Syndrome (HUS). The five main pathogenic serotypes of STEC (MPS‐STEC) identified thus far in Europe are O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28. Because STEC strains can survive or grow during cheese making, particularly in soft cheeses, a stochastic quantitative microbial risk assessment model was developed to assess the risk of HUS associated with the five MPS‐STEC in raw milk soft cheeses. A baseline scenario represents a theoretical worst‐case scenario where no intervention was considered throughout the farm‐to‐fork continuum. The risk level assessed with this baseline scenario is the risk‐based level. The impact of seven preharvest scenarios (vaccines, probiotic, milk farm sorting) on the risk‐based level was expressed in terms of risk reduction. Impact of the preharvest intervention ranges from 76% to 98% of risk reduction with highest values predicted with scenarios combining a decrease of the number of cow shedding STEC and of the STEC concentration in feces. The impact of postharvest interventions on the risk‐based level was also tested by applying five microbiological criteria (MC) at the end of ripening. The five MCs differ in terms of sample size, the number of samples that may yield a value larger than the microbiological limit, and the analysis methods. The risk reduction predicted varies from 25% to 96% by applying MCs without preharvest interventions and from 1% to 96% with combination of pre‐ and postharvest interventions.     

Group technology and growth at Shalibane

Abstract. The Shalibane Company of Camberley are tube manipulators and sheet metal workers, making parts mainly for the car industry. In 1991 they introduced Group Technology (GT). In eighteen months they reduced stocks by 60% (still falling); increased sales and output by 33%; increased the rate of return on investment by 24%; and increased the number of their employees by 12%. The cost of introducing the change was covered more than 3 times by the reduction in the stock investment. GT is shown to be a method which promotes growth and increases productivity, profitability and employment.     

The Bioaccessibility of Lead (Pb) from Vacuumed House Dust on Carpets in Urban Residences

Risk assessments for toxicants in environmental media via oral exposure often rely on measurements of total concentration in a collected sample. However, the human digestive system cannot dissolute all of a toxicant present in the binding matrix, and cannot absorb it with nearly 100% efficiency. In vitro bioaccessibility has been developed as a method to estimate oral bioavailability of a toxicant using a physiologically-based extraction procedure. Bioaccessibility measurements are more physiologically relevant than strong acid leaching measurements of concentration. A method for measuring bioaccessible lead in house dust was derived from the bioaccessibility method currently used for heavy metals in contaminated soils. House dust was collected from carpets in typical urban residences. Bioaccessible lead was measured in house dust (<75 microm) from the homes of 15 participants. The bioaccessibility ranged from 52.4% to 77.2% in gastric fluid, and 4.9% to 32.1% in intestinal fluid. House dust samples from five homes were analyzed to assess the relationship among lead bioaccessibility of three particle size fractions (<75, 75-150, and 150-250 microm). Changes in lead bioaccessibility as a function of particle size fraction were not significant for gastric fluid (p= 0.7019); however they were significant for intestinal fluid (p= 0.0067). This decrease of bioaccessibility may result from the readsorption of dissolved lead onto the dust particles or precipitation of lead with phosphates in a high-pH environment. The bioaccessibility data obtained for two biofluids were applied to the IEUBK model, and results for intestinal bioaccessibility of lead provide support for the model default value of 30% lead bioavailability of dust as a reasonable population indicator for dose, but the higher values for gastric bioaccessibility of lead appeared to provide an upper bound that approached actual blood lead levels in the children living in the studied homes. This upper bound seemed to overcome some of the limitations of the model when it lacks child-specific activity data and characterization of all exposure routes.     

Quantitative microbiological risk assessment of nontyphoidal Salmonella in ground pork in households in Chengdu,China

Foodborne disease caused by nontyphoidal Salmonella (NTS) is one of the most important food safety issues worldwide. The objectives of this study were to carry out microbial monitoring on the prevalence of NTS in commercial ground pork, investigate consumption patterns, and conduct a quantitative microbiological risk assessment (QMRA) that considers cross-contamination to determine the risk caused by consuming ground pork and ready-to-eat food contaminated during food handling in the kitchen in Chengdu, China. The food pathway of ground pork was simplified and assumed to be several units according to the actual situation and our survey data, which were collected from our research or references and substituted into the QMRA model for simulation. The results showed that the prevalence of NTS in ground pork purchased in Chengdu was 69.64% (95% confidence interval [CI], 60.2–78.0), with a mean contamination level of −0.164 log CFU/g. After general cooking, NTS in ground pork could be eliminated (contamination level of zero). The estimated probability of causing salmonellosis per day was 9.43E-06 (95% CI: 8.82E-06–1.00E-05), while the estimated salmonellosis cases per million people per year were 3442 (95% CI: 3218–3666). According to the sensitivity analysis, the occurrence of cross-contamination was the most important factor affecting the probability of salmonellosis. To reduce the risk of salmonellosis caused by NTS through ground pork consumption, reasonable hygiene prevention and control measures should be adopted during food preparation to reduce cross-contamination. This study provides valuable information for household cooking and food safety management in China.     

Application of Whole-Genome Sequences and Machine Learning in Source Attribution of Salmonella Typhimurium

Prevention of the emergence and spread of foodborne diseases is an important prerequisite for the improvement of public health. Source attribution models link sporadic human cases of a specific illness to food sources and animal reservoirs. With the next generation sequencing technology, it is possible to develop novel source attribution models. We investigated the potential of machine learning to predict the animal reservoir from which a bacterial strain isolated from a human salmonellosis case originated based on whole-genome sequencing. Machine learning methods recognize patterns in large and complex data sets and use this knowledge to build models. The model learns patterns associated with genetic variations in bacteria isolated from the different animal reservoirs. We selected different machine learning algorithms to predict sources of human salmonellosis cases and trained the model with Danish Salmonella Typhimurium isolates sampled from broilers (n = 34), cattle (n = 2), ducks (n = 11), layers (n = 4), and pigs (n = 159). Using cgMLST as input features, the model yielded an average accuracy of 0.783 (95% CI: 0.77–0.80) in the source prediction for the random forest and 0.933 (95% CI: 0.92–0.94) for the logit boost algorithm. Logit boost algorithm was most accurate (valid accuracy: 92%, CI: 0.8706–0.9579) and predicted the origin of 81% of the domestic sporadic human salmonellosis cases. The most important source was Danish produced pigs (53%) followed by imported pigs (16%), imported broilers (6%), imported ducks (2%), Danish produced layers (2%), Danish produced cattle and imported cattle (<1%) while 18% was not predicted. Machine learning has potential for improving source attribution modeling based on sequence data. Results of such models can inform risk managers to identify and prioritize food safety interventions.     

Methylmercury Risks and EPA + DHA Benefits Associated with Seafood Consumption in Europe

The intake of methyl‐Hg and EPA + DHA through consumption of seafood in Europe as well as the associated probability of exceeding the provisional tolerable weekly intake (PTWI) and the recommended daily intake (RDI), respectively, were estimated by combining methyl‐Hg and EPA + DHA contents in the five most consumed seafood species with hypothesized consumption distributions for eight European countries, chosen on the basis of size and representative significance. Two estimators were used: plug‐in (PI) and tail estimation (TE). The latter was based on the application of the extreme value theory to the intakes distribution curves. Whereas contents data were collected from own database and published scientific papers, consumption data were obtained from statistical sources of the various countries. Seafood consumption levels varied considerably between countries, from 140 in the United Kingdom to 628.5 g/(person.week) in Iceland. The main consumed species were also different between countries. The probability of exceeding the methyl‐Hg PTWI ranged from 0.04% in the United Kingdom to 9.61% in Iceland. Concerning the probability of exceeding the RDI of EPA + DHA, Iceland was third, after Portugal (66.05%) and Spain (61.05%) and the United Kingdom was the last (0.32%). While TE was most accurate for small probabilities, PI yielded best estimates for larger probabilities.