笔迹样本中的五种假象不容忽视

研究笔迹样本的一些特征,它既不是代表书写人的书写习惯,也不是书写人笔迹特征的本来面目,对此称之为特征假象。本文拟就对笔迹样本中产生假象的原因、表现形式(除意外产生)进行了研究,并对识别的办法进行探讨。     

Automated extraction of DNA from reference samples from various types of biological materials on the Qiagen BioRobot EZ1 Workstation

We have validated and implemented a protocol for DNA extraction from various types of biological materials using a Qiagen BioRobot EZ1 Workstation. The sample materials included whole blood, blood from deceased, buccal cells on Omni swabs and FTA Cards, blood on FTA Cards and cotton swabs, and muscle biopsies. The DNA extraction was validated according to EN/ISO 17025 for the STR kits AmpF?STR^® Identifiler^® and AmpF?STR^® Yfiler^® (Applied Biosystems). Of 298 samples extracted, 11 (4%) did not yield acceptable results. In conclusion, we have demonstrated that extraction of DNA from various types of biological material can be performed quickly and without the use of hazardous chemicals, and that the DNA may be successfully STR typed according to the requirements of forensic genetic investigations accredited according to EN/ISO 17025.     

泥土中花粉的环境扫描电镜研究

目的建立环境扫描电镜观察研究泥土中花粉的方法。方法泥土样品经过一系列酸碱浸泡、离心、过滤等处理后,经环境扫描电镜观察。环境扫描电镜采用样品室工作气压4.5torr,冷冻样品台温度5℃的工作条件。结果环境扫描电镜下观察到的花粉外壁雕纹饱满,层次感强,网状纹上的颗粒形态非常清晰,不同种花粉的外观形态特征各异。泥土样品提取后并可拍摄到清晰的花粉颗粒。结论采用环境扫描电镜可对泥土中花粉的形态进行观察,并可对已知花粉和未知花粉进行比较,进行种属鉴别。本方法可应用于实际案例,为鉴别花粉种类、确定泥土物证与犯罪现场的关系等提供科学依据。     

Guidelines for the identification of unknown samples for laboratories performing forensic analyses for chemical terrorism

Since the early 1990s, the FBI Laboratory has sponsored Scientific Working Groups to improve discipline practices and build consensus among the forensic community. The Scientific Working Group on the Forensic Analysis of Chemical, Biological, Radiological and Nuclear Terrorism developed guidance, contained in this document, on issues forensic laboratories encounter when accepting and analyzing unknown samples associated with chemical terrorism, including laboratory capabilities and analytical testing plans. In the context of forensic analysis of chemical terrorism, this guidance defines an unknown sample and addresses what constitutes definitive and tentative identification. Laboratory safety, reporting issues, and postreporting considerations are also discussed. Utilization of these guidelines, as part of planning for forensic analysis related to a chemical terrorism incident, may help avoid unfortunate consequences not only to the public but also to the laboratory personnel.     

应用Miseq FGx平台检测降解骨骼样本效果初探

目的评估Miseq FGx平台检测降解骨骼样本效果。方法对10例基于PCR-CE方法 STR分型结果不理想的降解骨骼样本用Miseq FGx平台检测,比较两个平台STR位点的检出结果和检出率。结果 10例降解骨骼样本在Mi Seq FGx平台上的STR位点检出率均高于PCR-CE方法,一些用PCR-CE方法没有检出的STR位点,很有可能在Miseq FGx平台中检出。同时,Miseq FGx平台测序还获得了X-STR、Y-STR、SNP等遗传标记的大量信息。结论 Mi Seq FGx平台检测降解骨骼样本有较好的应用价值。     

Optimization of the collection and analysis of touch DNA traces

The aim of this work was to optimize a strategy for detection, collection, and analysis of touch DNA traces. 4N6FLOWSwabs™ and cotton swabs were compared by collecting touch DNA traces from glass slides and gun shell casings. Shed cells were visualized using Diamond™ nucleic acid dye and a digital fluorescent microscope. Different collection and extraction methods were tested. Collected samples were amplified with the AmpFlSTR® NGMSElect™ kit and the Precision ID mtDNA Whole Genome Panel.     

乳牛布鲁氏菌病PCR诊断试剂盒的实验室评估

对前期研制的布鲁氏菌omp25基因-PCR试剂盒的保存期、特异性和可重复性进行了测定,并应用该试剂盒对采自宁夏、甘肃、内蒙古、山西、黑龙江、新疆省(区)的98头血清凝集试验(SAT)阳性乳牛的6批98份乳样和350头SAT阴性乳牛的2批350份乳样进行了检测。检测结果显示,PCR试剂盒与SAT的阳性符合率为100%(98/98),阴性符合率为97.71%(342/350);从SAT阴性乳牛的乳样中,用PCR试剂盒检出8份阳性,表明其敏感性高于SAT;对2株田间野毒Br-gs和Br-nmg株进行了克隆与测序,二者与标准菌株序列的同源性分别为99.8%和100%。试验结果证实,本试剂盒的可重复性良好,特异性较高,-20℃下的有效保存期为5个月。     

高效液相色谱法测定小鼠血清中可卡因的含量

目的 建立一种测定血清中可卡因含量的高效液相色谱方法。方法 以0.04mol/L磷酸盐缓冲液(含有0.26 mmol/L四丁基胺盐,pH3.2)-乙腈(83:17)为流动相,血清样品采用2％异戊醇正己烷-0.1 mol/L HCl液液反萃取法处理,用Kromasil C18色谱柱分析血清中可卡因的含量。紫外检测波长为235nm。结果可卡因的最小检出浓度为25ng/ml,回收率71％。结论所建方法测定血清中可卡因含量灵敏度高,简便易行。     

免疫抗A、抗B、抗H沉淀素血清的制备

本文介绍了用浓缩的分泌型人唾液免疫鸡,经吸收精制获得鸡抗A、抗B、抗H沉淀素血清的方法。用本法制备的抗血清,对相应血型人唾液的特异性沉淀价可达1:512倍以上,对非相应血型者的分泌液不出现非特异性沉淀反应。应用该血清进行环状沉淀试验、单向琼脂扩散试验等免疫学试验,可简便、准确地鉴定人唾液斑、精液斑等分泌液斑的ABO血型。     

玻璃折射率数据处理方法初探

目的探讨玻璃折射率数据处理方法。方法将案件中收集到的45个玻璃样品和同一个车灯不同部位的45块玻璃样品进行折射率测定。用独立样本Student’st检验、welch检验以及方差分析（ANOVA）对数据进行成对检验。结果方差分析法中Dunnett’s C法处理玻璃折射率数据,有效控制了第一类和第二类错误。当α=0．05时,犯第一类错误的概率约为4．44％,犯第二类错误的概率约为3．54％。