Determination of the sequence of intersecting lines using Focused Ion Beam/Scanning Electron Microscope

The aim of this study was to verify that the combination of focused ion beam (FIB) and scanning electron microscope/energy‐dispersive X‐ray (SEM/EDX) could be applied to determine the sequence of line crossings. The samples were transferred into FIB/SEM for FIB milling and an imaging operation. EDX was able to explore the chemical components and the corresponding elemental distribution in the intersection. The technique was successful in determining the sequence of heterogeneous line intersections produced using gel pens and red sealing ink with highest success rate (100% correctness). These observations show that the FIB/SEM was the appropriate instrument for an overall examination of document.     

GSR2005—Continuity of the ENFSI Proficiency Test on Identification of GSR by SEM/EDX

Abstract:  Within the framework of the ENFSI Expert Working Group "Firearms" a proficiency test on the detection and identification of GSR by energy-dispersive scanning electron microanalysis (SEM/EDX) is carried out in a 2 years term. The latest test was performed in 2005/2006 and was denoted as GSR2005 . Seventy-five laboratories from 28 countries participated in this proficiency test and submitted in total 83 independent data-sets. The participating laboratories were requested to determine the total number of PbSbBa containing particles on a synthetic test sample following their own laboratory specific methods of automated GSR particle search and detection by SEM/EDX. Furthermore size and position of the detected particles had to be reported by the laboratories and were evaluated statistically. The results were compiled by means of z -scores according to the IUPAC and EURACHEM guidelines—assessing individual laboratory achievements (inter-laboratory) as well as intra-laboratory performance—and were compared to the results of the previous proficiency test run GSR2003 ( 1 ). The comparison shows that there is a noticeable improvement in the method's detection capability.     

Vitality and age of conjunctival petechiae: The expression of P-selectin

Confocal laser scanning microscopy (CLSM) results in displaying multiple ruptures of capillaries and venules define conjunctival petechiae as a rhexis haemorrhage. In order to distinguish between petechiae which have arisen before death as opposed to post-mortem artefacts and the establishment of the age of the vessel's damage, we carried out an investigation on a collection of samples from medico-legal cases (positive petechiae: n = 65; post-mortem artefacts: n = 12; control: n = 19) to establish whether the expression of the endothelial adhesion molecule P-selectin as demonstrated by immunohistochemical methods is influenced by trauma before death and possibly by time. Except for cases with massive congestion in those cases where the victim had survived for around minutes, CLSM examination revealed a strong endothelial reaction at the site where the vessel had ruptured. It was impossible to detect a strong P-selectin expression signal in both those vessels which had not suffered any mechanical insult and those which had experienced post-mortem rupture. Therefore, the elevated expression of P-selectin can be used as a criterion to distinguish between those lesions which have occurred in life and those which are post-mortem artefacts.     

Evaluation of the Differex™ System

Differential extraction is an efficient method to separate sperm cells from epithelial cells. A manual Chelex^®-100 based method is used at the Swedish National Laboratory of Forensic Science, SKL. The Differex™ System (Promega) uses a Proteinase K digestion of epithelial cells followed by centrifugation and phase separation. The sperm- and epithelial fractions are further purified with DNA IQ™ System (Promega) or with phenol/chloroform. The Differex™ System in combination with DNA IQ™ System were evaluated and compared to the Chelex^®-100 method used routinely. After modifications, the Differex™ System gave comparable results to the Chelex^®-100 method. The modifications included additional Proteinase K and DTT, longer incubation time and additional steps when removing the solid support from the Digestion Solution. In the Chelex^®-100 based method microscopic examination is done on the sperm pellet in a total volume of 50 μl. It was not possible to do a microscopic examination in less than 100 μl using the Differex™ System. Additionally the sperms were in clusters of epithelial cell debris. Microscopic examination is an important part of the differential extraction at SKL. Therefore, the Differex™ System will not be implemented at our laboratory.     

差示分光光度法测定双氯灭痛片的含量

目的：采用差示分光光度法测定双氯灭痛片剂的含量，方法：在波长２９０ｎｍ处，以双氯灭痛在０．０１ｍｏｌ／Ｌ氢氧化钠溶液为参比液，测其在乙醇中的差示吸收值，结果：双氯灭痛浓度在１１～５０μｇ／ｍｌ范围内△Ａ与溶液浓度呈良好线性关系（ｒ＝０．９９９６）平均回收率为１００．６％，ＲＳＤ为０．６４％，结论：该法简便，快速，准确。     

Transfer and Distribution of Gunshot Residue through Glass Windows

Research into the deposition patterns of primer gunshot residue (GSR) beyond a primary target was previously nonexistent. This study aimed to determine the deposition patterns of GSR once a bullet passed through an initial target and continued on its path into additional targets. Multiple repetitions were performed to assess the GSR deposition patterns after a bullet was shot through a closed window into either a dummy or a wall within an enclosed room. Samples were taken from both the primary and secondary target holes as well as from nontarget areas. Significant amounts of GSR were found on all samples. The results show that GSR continues to be deposited along the path of the bullet after passing through a primary glass target. These findings reiterate the lack of probative value in collecting GSR samples from gunshot victims even if they are in an enclosed area separate from the shooter.     

微波消解-扫描电镜联用检测脏器内硅藻

目的介绍一种微波消解-扫描电镜联用检测脏器内硅藻的新方法。方法大白兔30只,随机分为生前溺死组（n=15）和死后溺尸组（n=15）。提取兔肺、肝、肾、股骨骨髓和现场珠江水样,采用建立的微波消解-扫描电镜联用法检测脏器组织和水样中的硅藻,并与硝酸乙醇消解-扫描电镜联用的方法进行比较。结果生前溺死组的兔肺、肝、肾、股骨骨髓组织中大多数观测到与现场珠江水样一致的硅藻,微波消解-扫描电镜联用法检测脏器内硅藻的平均含量分别为：2505.2个/2g肺,18.7个/10g肝,6.5个/10g肾,6.3个/0.5g骨髓;肺与肝、肾、骨髓检出硅藻的阳性比例为86.7%,脏器硅藻检出含量和硅藻检验阳性比例均明显高于硝酸乙醇消解-扫描电镜联用法所测值。死后溺尸组的兔脏器组织均未观测到硅藻。结论微波消解-扫描电镜联用法检测脏器内硅藻,高效、安全、环保,硅藻检验灵敏度高,降低了劳动强度,提高了定性定量分析准确度,且能有效避免污染,在法医学溺死鉴定中具有良好的应用价值。     

Detection of Gunshot Residue in Blowfly Larvae and Decomposing Porcine Tissue Using Inductively Coupled Plasma Mass Spectrometry (ICP‐MS)*

Abstract: Blowfly larvae and porcine tissue contaminated with gunshot residue (GSR) were collected during summer and winter months, over a 37‐day and a 60‐day sampling period, respectively. Wound samples were microwave‐digested and analyzed by inductively coupled plasma mass spectrometry (ICP‐MS) for the detection of antimony, barium, and lead. During summer, the 37‐day sampling period encompassed all stages of decomposition, except skeletonization. The three elements were detected in larvae only on days 3 and 4 after death but were detected at significant levels in tissue samples throughout the entire sampling period. In winter, no significant decomposition was observed throughout the 60‐day sampling. Although temperatures were too low for blowfly activity, the three elements were detected in the tissue samples at relatively constant, significant levels. Hence, GSR determination in tissue was more dependent on decomposition stage rather than time since death.     

Automated SEM/EDS Analysis of Airbag Residue. II: Airbag Residue as a Source of Percussion Primer Residue Particles

Abstract:  Automated scanning electron microscopy with energy dispersive spectroscopy has been used to analyze airbag residue particles. Analysis of airbag residue from some passenger side airbags revealed some residue particles which are consistent with gunshot residue (GSR) samples. The source of these particles was determined to be percussion primers used to initiate the chemical reaction for deployment. This article identifies some vehicles which contain this type of airbag and demonstrates the types of particles which could be misidentified as being GSR. The low numbers of GSR particles in among the large particle populations of zirconium and/or copper–cobalt particles, which are clearly airbag residue, allow the trained analysts to distinguish the correct source of this residue. Particles containing high aluminum levels, elevated levels of allowable elements in GSR particles, or the presence of elements that are rare in GSR particles stand out as indications that the particles are not GSR in origin. This study serves as a guide to analysts who perform particle analysis in forensic investigations.     

绵羊肺泡毛细血管的扫描电镜观察

运用血管铸型和扫描电镜技术对绵羊肺实质内微血管的构筑特征进行了观察,旨在揭示绵羊肺泡毛细血管的分布特征,为哺乳动物肺微血管的研究积累资料,并为牦牛肺微血管的进一步研究奠定基础。观察结果显示,低倍镜下,在截面上可见肺实质内的微血管网均呈大小不等的蜂窝状结构,肺泡囊和肺泡的轮廓清晰可见;高倍镜下肺泡毛细血管网呈网络状,视野内大部分肺泡毛细血管网伸展良好。经与文献中有关动物肺泡毛细血管的研究结果相比较,本试验中绵羊肺泡毛细血管的构筑特征与新生牦牛、双峰驼相近,而与人、犬、猴、兔、鼠等动物差别较大。