Zero Risk Does Not Exist: Lessons Learned from Microbial Risk Assessment Related to Use of Water and Safety of Fresh Produce

Risk assessments related to use of water and safety of fresh produce originate from both water and food microbiology studies. Although the set‐up and methodology of risk assessment in these 2 disciplines may differ, analysis of the current literature reveals some common outcomes. Most of these studies from the water perspective focus on enteric virus risks, largely because of their anticipated high concentrations in untreated wastewater and their resistance to common wastewater treatments. Risk assessment studies from the food perspective, instead, focus mainly on bacterial pathogens such as Salmonella and pathogenic Escherichia coli. Few site‐specific data points were available for most of these microbial risk assessments, meaning that many assumptions were necessary, which are repeated in many studies. Specific parameters lacking hard data included rates of pathogen transfer from irrigation water to crops, pathogen penetration, and survival in or on food crops. Data on these factors have been investigated over the last decade and this should improve the reliability of future microbial risk estimates. However, the sheer number of different foodstuffs and pathogens, combined with water sources and irrigation practices, means that developing risk models that can span the breadth of fresh produce safety will be a considerable challenge. The new approach using microbial risk assessment is objective and evidence‐based and leads to more flexibility and enables more tailored risk management practices and guidelines. Drawbacks are, however, capacity and knowledge to perform the microbial risk assessment and the need for data and preferably data of the specific region.     

包装机械CAI课件设计

本文结合包装机械学课程的特点，对其CAI课件进行了研究和开发。课件系统包括三个主要部分：包装机械学计算机辅助学习系统，主要内容包括包装机械学的基本概念、方法、理论、例题、练习题；包装机械的仿真与模拟系统，基本内容包括典型整机的图片、基本构件工作原理的仿真与模拟；包装机械学综合测评系统，内容有检测题、试卷、试卷答卷。     

胰腺癌综合治疗现状及其价值

任何单一疗法治疗胰腺癌都难以获得理想的疗效。目前,可切除胰腺癌的治疗仍以根治性切除为主。放射治疗与手术联合应用,可提高手术切除率,减少肿瘤扩散;术中放疗可以缓解疼痛,提高生存率;对术后辅助放化疗的作用仍有争议。区域性化疗理论上有诸多优势,但仍需数据支持。物理治疗和生物治疗在胰腺癌的治疗中也已经得到广泛的重视。但只有建立以手术切除为主,联合放疗、化疗、物理及生物治疗的综合治疗体系,才有可能根本改变治疗现状,显著提高长期生存率,并改善生活质量。介入治疗作为重要的姑息治疗方法之一,近年来得到了长足的发展。     

覆膜Y型单子弹头气道支架治疗左主支气管胸膜瘘12例

【摘要】 目的 评估应用Y型单子弹头覆膜气道支架封堵残端较短的左主支气管胸膜瘘的临床效果。方法 回顾性分析2010年8月—2013年9月收治的12例残端较短的左主支气管胸膜瘘患者,根据这类患者支气管残端较短的解剖结构特点,个体化定制Y型单子弹头覆膜气道内支架。在X线监视下,12例患者共置入12枚Y型单子弹头内支架。观察患者支架置入后瘘口愈合情况。结果 12枚支架均一次性置入成功,内支架置入后瘘口即刻完全封堵,随访3 ～ 17个月;6例瘘口封堵良好,支架置入后3个月取出,瘘口愈合、残腔消失;5例复查胸部多排螺旋CT（MSCT）显示支架子弹头部周围软组织较薄,残腔较前明显缩小,未取出支架,继续负压引流,带支架生存至今。1例高龄患者,支架置入前已存在重度肺部感染,支架置入后瘘口虽即刻完全封堵,但术后未能控制原有肺部感染,加之体质虚弱,术后2周死于肺部重度感染和机体衰竭。结论 应用Y型单子弹头覆膜自膨式内支架封堵残端较短的左主支气管胸膜瘘患者的瘘口,近期临床效果可靠,值得推广应用。
     

经皮椎体成形术临床应用—— — 附２９５例５５３节椎体报告

目的评价经皮椎体成形术（PVP）临床疗效、适应证及相关技术。方法对２９５例患者５５３个椎体在X线C臂血管机导引下行PVP,包括骨质疏松症１７１例,转移性肿瘤１０３例,骨髓瘤１２例,血管瘤２例,外伤７例。一般采用单侧椎弓根穿刺,骨水泥量为２～７ml 。结果骨质疏松症患者总有效率为９４．１％（１６１／１７１）,转移性肿瘤总有效率为８１．５％,骨髓瘤患者有效为８例（８／９）,外伤患者有效为７例（７／７）。本组患者无严重并发症;１８例转移瘤PVP后３～４d行放射治疗;１２例采用大平板血管机旋转X线采集和椎体三维重建成像指导手术操作。结论PVP已成为疼痛性压缩性骨折标准治疗方法之一,伴随手术方法和器材不断改进其适应证必将不断扩大。     

低速船用柴油机主轴承弹流润滑性能分析

以某低速二冲程船用柴油机为研究对象，结合弹性流体动力学、多体动力学以及有限元方法，建立了包含机架-机座-主轴承盖-曲轴的整机动力学润滑耦合分析模型，对低速船舶柴油机主轴承的润滑性能进行研究。研究结果表明:第7主轴承(靠近飞轮端)润滑性能最为恶劣，总压峰值达到87.95 MPa，高出其他主轴承19.7%至413.7%不等；在整个推进工况主轴承油膜厚度均满足最小膜厚要求；不同工况轴承液动润滑和混合润滑的时间占比也不尽相同，液动润滑占比从100%负荷的20.7%提高到25%负荷的99.3%；轴承结构对主轴承的润滑磨损性能有较大影响，径向间隙的设计须综合考虑油膜承载与摩擦功耗。     

柴油机机油耗高的排查改进及控制

介绍了柴油机机油消耗高的排查方法,通过对机油消耗率影响因素的分析,进行试验和测量,提出了设计改进措施和质量控制措施,使柴油机机油消耗率得到了进一步降低,同时也促进了柴油机的环保排放达标。     

Development and validation of a new LC–MS/MS method for the simultaneous determination of six major ergot alkaloids and their corresponding epimers. Application to some food and feed commodities

A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous determination of six major ergot alkaloids, ergometrine, ergosine, ergotamine, ergocornine, ergokryptine and ergocristine, as well as their corresponding epimers in food and feed samples. The method involves extraction under alkaline conditions and subsequent clean-up by applying a simple and rapid liquid–liquid partitioning procedure prior to LC–MS/MS analysis. Evaluation of the method revealed good linearity, accuracy and precision. The limits of quantification varied from 0.1 to 1 μg/kg depending on the analyte and matrix. The average extraction and clean-up recoveries in different matrices were between 45 (only for ergometrine in biscuit) and 90%. The uncertainty associated with the analytical method was not higher than 51% and 30%, at concentration levels of 2.5 and 150 μg/kg respectively. Analyte epimerization proved to be minimal during the analytical procedure. The method has been successfully applied to the determination of ergot alkaloids in some Belgian food and feed commodities. Ergot alkaloids were found in 104 out of 122 samples investigated. Ergosine was the most frequently occurring alkaloid, while the highest levels were observed for ergotamine, ergocristine or ergosine, depending on the product type. The total alkaloid content in positive samples varied from 1 to 1145 μg/kg.     

Effect of sourdough fermentation on stabilisation,and chemical and nutritional characteristics of wheat germ

Lactic acid bacteria strains were identified from wheat germ by 16S rRNA partial sequencing, subjected to RAPD-PCR typing and screened. Lactobacillus plantarum LB1 and Lactobacillus rossiae LB5 were used as starters to produce sourdough fermented wheat germ (SFWG). The chemical and nutritional characteristics of SFWG were compared to those of the raw wheat germ (RWG). Lipase activity in SFWG was ca. 2.6-fold lower than that found in RWG. As shown by SPME/GC/MS analysis, most of the volatile compounds derived from lipid oxidation during storage (40 days) were at markedly lower levels in SFWG compared to RWG. Fermentation of wheat germ increased of ca. 50% the concentration of free amino acids. Glu markedly decreased in SFWG, due to its conversion in GABA. The concentration of the anti-nutritional factor raffinose also decreased in SFWG. The in vitro protein digestibility, the concentration of total phenols, phytase and antioxidant activities were increased by fermentation.     

Comparison of volatile components in raw and cooked green beans by GC-MS using dynamic headspace sampling and microwave desorption

 The effects of four culinary treatments (steaming and boiling in a covered pot, a pressure cooker or a microwave oven) on the volatile component profile of green beans were evaluated. Volatile compounds in raw and cooked beans were analysed by means of dynamic headspace sampling onto an adsorbent, followed by microwave desorption into a gas chromatograph equipped with a mass spectrometric detector. Twenty-seven compounds were identified, including alcohols, aldehydes, ketones, esters, terpenes, sulphur compounds and alkenes. All of the thermal treatments caused important changes in the volatile compound profile in particular an increase in carbonyl compounds and a decrease in alcohol compounds, most notably in the case of the covered pot. It is concluded that the change in aroma during the cooking of green beans depends on compounds from lipid oxidation as well as compounds from other types of reactions, for instance the Strecker degradation. Received: 8 March 1999 / Revised version: 23 April 1999