Identification of wires and the cutting tool by scanning electron microscope

The cut ends of aluminium and copper wires made by different pliers have been compared under the scanning electron microscope to correlate the two pieces of a wire and to identify the cutting tool. The mechanism of producing the cut ends has been discussed. Matching of extrusion marks and correspondence of breakages at the edges of the cut ends were observed. Correspondence between the fine striations was observed on the opposite faces. These features are put forward for assigning a cut wire to a source.The ends produced by repeatedly cutting a wire by the same portion of the edge of a pair of pliers have been compared. It was found that the striations and fracture zones were reproduced on the respective surfaces of the consecutive cut ends. To identify the cutting tool in wire theft cases, it is suggested that the trial cut ends can be made by cutting the wire with successive portions of the edge of the suspected tool and compare the surface features with that on the questioned ones.     

SD大鼠闭合性小脑挫伤的透射电镜观察

目的　探讨闭合性小脑挫伤病变发生发展过程。　方法　建立闭合性小脑挫伤动物模型 ,分别于损伤后不同时间组 5min、10min、3 0min、45min、60min、2h、4h、6h、8h、12h与正常组对照 ,观察其电镜变化。　结果　损伤后不同时间组 ,小脑蒲肯野氏细胞线粒体水肿、空泡化从轻到重 ,线粒体嵴逐渐消失。神经纤维髓鞘疏松断裂 ,神经原丝及微管结构模糊 ,并随着时间推移 ,其损伤越来越重。损伤后 3 0min ,线粒体胞浆中充满了游离核糖体。损伤后 1～ 2小时小脑蒲肯野氏细胞胞浆浓缩 ,细胞核开始发生染色质边集。个别细胞核发生核溶解。至 4～ 6小时小脑蒲肯野氏细胞细胞核坏死发展到高峰 ,然后逐渐减轻。损伤后 8小时 ,小脑血管内皮细胞线粒体水肿 ,嵴消失 ,神经纤维髓鞘松解 ,胶质细胞核周间隙扩张。　结论　闭合性小脑挫伤后不同时间电镜变化 ,为早期损伤时间推断的法医学鉴定提供了病理学基础。     

The determination of sequence of crossing strokes by the “Kromekote” paper lifting process and by the scanning electron microscopic method

The authors present the results obtained while applying the “Kromekote paper” lifting process first proposed by Igoe and Reynolds in 1979 [1] and later in a modified form in 1980 and 1982 by Godown [2]. They also present the results of their research to determine the writing order of crossing strokes using the Scanning Electron Microscopic technique, research that was restarted after the publication of an article by Waeschle [3].     

A Study of the Presence of Gunshot Residue in Pittsburgh Police Stations using SEM/EDS and LC‐MS/MS

Due to possible secondary transfer of gunshot residue (GSR) onto a suspect in police custody prior to sampling, a baseline must be created for the amount of GSR present. With an increase of “lead free” ammunition, testing for both gunpowder and primer GSR is relevant. Seventy samples were collected using carbon‐coated adhesive stubs from four Pittsburgh Police Stations and vehicles to investigate these locations as sources of secondary GSR contamination. These seventy samples were analyzed for primer GSR using scanning electron microscopy‐energy‐dispersive X‐ray spectrometry. One primer GSR particle was detected; no sample was classified as positive for primer GSR. These same samples were then analyzed for gunpowder GSR using liquid chromatography coupled to tandem mass spectrometry to test for akardite II, ethylcentralite, diphenylamine, N‐nitrosodiphenylamine, 2‐nitrodiphenylamine, and 4‐nitrodiphenylamine. Ethylcentralite was quantifiable in two test samples. These results suggest there is a negligible potential for secondary transfer of primer and gunpowder GSR.     

On the challenge of unambiguous identification of fentanyl analogs: Exploring measurement diversity using standard reference mass spectral libraries

Fentanyl analogs are a class of designer drugs that are particularly challenging to unambiguously identify due to the mass spectral and retention time similarities of unique compounds. In this paper, we use agglomerative hierarchical clustering to explore the measurement diversity of fentanyl analogs and better understand the challenge of unambiguous identifications using analytical techniques traditionally available to drug chemists. We consider four measurements in particular: gas chromatography retention indices, electron ionization mass spectra, electrospray ionization tandem mass spectra, and direct analysis in real time mass spectra. Our analysis demonstrates how simultaneously considering data from multiple measurement techniques increases the observable measurement diversity of fentanyl analogs, which can reduce identification ambiguity. This paper further supports the use of multiple analytical techniques to identify fentanyl analogs (among other substances), as is recommended by the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG).     

Fragrance transfer between fabrics for forensic reconstruction applications

Sexual assault is a serious crime that often has low conviction rates. Recent literature has demonstrated that there is potential for fragrances to be valuable in forensic reconstructions where there has been contact between individuals. However, developing appropriate evidence bases for understanding the nature of fragrance transfer in these contexts is needed. This article presents three experiments that address the transfer process of fragrances that have been transferred from a primary piece of fabric onto a secondary piece of fabric, in a manner that could occur during an assault. The three variables studied were the ageing time of the fragrances on the first fabric prior to transfer, the contact time between the two fabrics, and lastly the fabric type (of the primary material and the recipient material). The transfer was evaluated using a validated solid phase micro-extraction gas chromatography–mass spectrometry (SPME GC–MS) method. The findings demonstrated that all three variables had an impact on the transfer of fragrances between clothing fabrics. Generally, lower volatility compounds were transferred and recovered in larger amounts than higher volatility compounds. All fragrance compounds were successfully recovered from a secondary piece of fabric even when the contact time was as short as 10 s, and even when the perfume was aged on the primary fabric for as long as 48 h. The nature of the fragrance transfer also depended on the fabric type, so that a clear discrimination was observed between the fragrance transfer that occurred onto a natural fabric (cotton) and onto a synthetic fabric (polyester).     

Automated SEM/EDS Analysis of Airbag Residue.* I: Particle Identification

Abstract: Deployed airbags can be a valuable source of probative forensic materials. During an accident, trace evidence can be deposited on the airbag cover and in addition, the residue produced by the gas generation system is released into the passenger compartment of the vehicle as the airbag deflates. This residue can be used to associate a suspect with the vehicle at the time of the accident. This study identifies particles containing zirconium, strontium, and/or copper–cobalt along with other elements from the gas generation systems and aluminum silicon microfibers from airbag filters as the probative material which may be produced and deposited on a suspect’s hands and/or clothing. Scanning electron microscopy can be used to identify this metallic residue. Modification of the search criterion used for gunshot residue analysis allows for automated analysis of the samples. Proper collection of the airbag standard is essential to identify which materials were produced. Prompt collection of suspect samples allows the analysts the ability to make the proper identifications and associations. This analytical technique can be a probative tool in criminal investigations.     

The ultrastructure of tissue attached to telogen hair roots

Most tissues encountered in forensic biology laboratories have been previously characterized with electron microscopy due to their medical importance. Anagen hair root cells, epithelial cells, erythrocytes, neutrophils, osteocytes, and spermatozoa have received considerable research attention at the ultrastructural level. There is no literature indicating that cells attached to removed telogen hair roots have been characterized with transmission electron microscopy. Nonetheless, telogen hairs are a frequent submission item to forensic laboratories for DNA typing. The amount of tissue attached to a telogen hair root usually determines whether that hair is suitable for nuclear DNA typing methods or mitochondrial DNA typing methods. This study used transmission and scanning electron microscopy to characterize the tissues found in three commonly occurring telogen hair root forms. The tissues were found to consist of keratinized remnant follicle, nonnucleated epithelial cells, nucleated epithelial cells, and trichilemmal keratin. These findings were consistent with the known principles of hair follicle regression. The recognition of the root structures that contain these specific tissue types may assist in the DNA typing of telogen hairs inasmuch as the quality of tissue present may be more important than the amounts of tissue present.     

便携式血液中CO检测仪的研制与应用研究

目的 依据分光光度计还原法原理,利用微型锂电池、传感器、全分析系统,研制特定波长便携式血液中CO检测仪.方法 选择以发光二极管(LED)为光源的单光源模式,以比色皿为样品池,设置内部参比,对光强进行校正.整个系统进行集成,实现数据采集、信号处理和运算一体化,直接显示测定结果.结果 最终形成体积小、质量轻、操作简便、检测...     

Characterisation and discrimination of so-called metallised fibres found in clothing and decorative materials originating from the consumer market

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