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.     

信息时代的企业工会工作

信息时代的出现给现代企业工会工作带来新的机遇 ,工会工作应以全新的观念和创造性的思路 ,积极主动地建立网络信息系统 ,以推进厂务公开、推广电子商务和加强知识管理为契机 ,推动企业民主化管理向纵深方向发展 ,在新的领域发挥重要作用。     

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。     

A survey of background levels of explosives and related compounds in the environment

In this paper, swabbings from various public areas in 28 different cities throughout the United States were collected. A wide variety of objects were tested, ranging from park benches and telephones to sign posts and mailboxes. Inorganic anions and cations common in low explosives were detected simultaneously using capillary zone electrophoresis. Organic high explosives including nitroaromatics, nitramines, and nitrate esters were detected using gas chromatography with a pulsed-discharge electron capture detector. Confirmation of selected results was performed by ion chromatography and negative ion chemical ionization GC/MS. In general the results provide two major conclusions: (i) with the exception of nitrate, most low explosive oxidizers are rare in the environment; (ii) no organic explosives or significant interferences to these explosives were detected.     

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.     

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.     

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。     

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.     

用SEM观察真皮浅层微小刺伤的研究

本文报道了一种用酶水解表皮与真皮的连接,然后用扫描电镜观察微小损伤在真皮乳头层的损伤特点的新方法。研究结果表明,这种方法有利于微小刺伤的鉴定,并提供一些具体的鉴定指标。     

Fast gas chromatography of explosive compounds using a pulsed-discharge electron capture detector

The detection of a mixture of nine explosive compounds, including nitrate esters, nitroaromatics, and a nitramine in less than 140 sec is described. The new method employs a commercially available pulsed-discharge electron capture detector (PDECD) coupled with a microbore capillary gas chromatography (GC) column in a standard GC oven to achieve on-column detection limits between 5 and 72 fg for the nine explosives studied. The PDECD has the benefit that it uses a pulsed plasma to generate the standing electron current instead of a radioactive source. The fast separation time limits on-column degradation of the thermally labile compounds and decreases the peak widths, which results in larger peak intensities and a concomitant improvement in detection limits. The combination of short analysis time and low detection limits make this method a potential candidate for screening large numbers of samples that have been prepared using techniques such as liquid-liquid extraction or solid-phase microextraction.