First-trimester screening: dealing with the fall-out

The articles collected together in this issue describe first-trimester screening for a variety of complications. With the advance of both technology and research, early pregnancy screening is becoming ever more sophisticated and complex. While there are clear benefits to most women receiving early reassurance that their baby is developing as expected, there is no evidence to suggest that an earlier prenatal diagnosis has less long-term emotional impact than at later gestations. The poignancy of ultrasound images for many parents means that it can be especially difficult to manage the anxiety when an ultrasound marker is highlighted as potential cause for concern. They can then face a journey of anxiety-laden uncertainty, which can extend through much of the pregnancy, and even beyond. Professionals involved in screening need to recognise and acknowledge such adverse side-effects and develop the skills necessary to help parents understand and cope with the uncertainties inherent in the process. Copyright © 2011 John Wiley & Sons, Ltd.     

Validation of Microtox as a first screening tool for waste classification

The Waste Framework Directive (WFD; 2008/98/EG) describes how waste materials are to be classified as hazardous or not. For complex waste materials chemical analyses are often not conclusive and the WFD provides the possibility to assess the hazardous properties by testing on the waste materials directly. As a methodology WFD refers to the protocols described in the CLP regulation (regulation on Classification, Labeling and Packaging of chemicals) but the toxicity tests on mammals are not acceptable for waste materials. The DISCRISET project was initiated to investigate the suitability of alternative toxicity tests that are already in use in pharmaceutical applications, for the toxicological hazard assessment of complex waste materials. Results indicated that Microtox was a good candidate as a first screening test in a tiered approached hazard assessment. This is now further validated in the present study. The toxic responses measured in Microtox were compared to biological responses in other bioassays for both organic and inorganic fractions of the wastes. Both fractions contribute to the toxic load of waste samples. Results show that the Microtox test is indeed a good and practical screening tool for the organic fraction. A screening threshold (ST) of 5 geq/l as the EC₅₀ value in Microtox is proposed as this ST allows to recognize highly toxic samples in the screening test. The data presented here show that the Microtox toxicity response at this ST is not only predictive for acute toxicity in other organisms but also for sub lethal toxic effects of the organic fraction. This limit value has to be further validated. For the inorganic fraction no specific biotest can be recommended as a screening test, but the use of direct toxicity assessment is also preferable for this fraction as metal speciation is an important issue to define the toxic load of elutriate fractions. A battery of 3 tests (Microtox, Daphnia and Algae) for direct toxicity assessment of this fraction is recommended in literature, but including tests for mechanistic toxicity might be useful.     

生活垃圾生物预处理后筛分及分选特性试验研究

堆肥化技术作为垃圾预处理方式在国内外已得到了广泛认可.本文通过现场试验,研究了生物预处理对垃圾筛分和分选特性的影响.结果表明,预处理后垃圾含水率降低了7.69%,堆体的体积从275 m~3减少到183 m~3,垃圾的容重从最初的356 kg·m~(-3)增加到470 kg·m~(-3).经过生物预处理,有机物不断被降解.预处理可以提高筛分后筛下物比例,预处理后的筛下物百分比提高了17%.预处理对可回收成分(金属、塑料、纸张、玻璃和布匹等)分选效率都较新鲜垃圾有不同程度的提高,对金属分选效果提高最显著,达到22.01%.本研究表明,生物预处理对垃圾筛分和分选均具有积极的作用,可以提高后期资源回收利用率.     

濒危植物厚朴SSR引物筛选及反应体系优化

探索适宜厚朴(Magnolia officinalis)简单重复序列(simple sequence repeat,SSR)-聚合酶链式反应(polymerase chain reaction,PCR)的最佳条件.在SSR引物筛选基础上,利用正交试验设计对影响PCR反应的5个因素(模板DNA、引物、Mg2+、dNTPs和Taq酶催化活性浓度)进行4个水平的优化,并通过温度梯度试验优化引物退火温度.在厚朴及其近缘物种的70对引物中,筛选出13对扩增条带清晰、多态性丰富的SSR引物.PCR各因素在不同水平下对反应体系的影响由大到小依次为引物浓度、Taq酶催化活性浓度、Mg2+浓度、dNTPs浓度和模板DNA浓度.PCR最佳优化体系:25 μL体系中,模板DNA质量浓度为2 ng·μL-1,引物浓度为0.6μmol·L-1,Mg2+浓度为2.0 mmol·L-1,dNTPs浓度为0.5 mmol·L-1,Taq酶催化活性浓度为0.03 U·μL-1(1U=16.67 nkat).最佳扩增程序:94℃预变性4 min,94℃变性30 s,48.0～59.0℃(退火温度随引物不同而定)退火30 s,72℃延伸1 min,35个循环后72℃延伸10 min.上述结果可为利用SSR-PCR技术研究濒危厚朴群体遗传学和分子生态学提供技术参数.     

常规试验设备温度循环应力筛选技术改进

目的寻找基于常规试验设备温度循环应力筛选技术的改进方法。方法应用常规温度循环试验箱,结合对军用电子产品进行环境应力筛选(ESS)的实际情况,测量产品在温度循环应力筛选时,产品内部升降温的实际速率,通过对这些测量结果比较分析,找出这一方法存在的问题,特别是缺陷暴露程度与应力筛选的相关性差,通过对温度循环筛选参数的合理选择进行分析,找出解决这一问题的思路。结果理论筛选度较高(如0.89)的试验,实际测算额得出的筛选度很低(如0.54)。结论应用温度循环应力筛选的方法,确立合理的应力参数,就可取得理想的试验效果,节省一半的试验时间。