Zur ultrastruktur vitaler,postmortaler und autolysierter gerinnsel

Investigations on animal experimental and human tissue material (skin, musculature, liver) with the scanning electron microscope are reported. These studies were carried out to clarify open questions on extravascular fibrin structures after blunt and sharp traumatization of vital and postmortem nature. The network formation which was already characterized earlier as typically vital and the irregular structure of postmortem coagula could be demonstrated even with modification of the traumatization, especially in tissue hematomas. Experimental investigations on autolysis revealed an exceedingly good preservation of the structure of vital coagulum material with massive damage and granular decomposition of fibrin fiber structures produced postmortem. The structural differences in the mode of interlinking of the fibrin was shown up especially clearly by the autolysis, which suggests an application as preparation technique for the question specified.Special modifications of the preparation technique (fixation according to Karnovsky, critical-point drying) did not provide such substantial advantages for routine investigations that they might be generally recommended.Sources of artefacts and possibilities of misinterpretation of findings as well as more advanced techniques are discussed.     

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.     

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.     

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.     

A Novel Approach to the Examination of Soil Evidence: Mineral Identification Using Infrared Microprobe Analysis*

Abstract: Identification of minerals using the infrared microprobe with a diamond internal reflection objective is a rapid and reliable method for forensic soil examinations. Ninety‐six mineral varieties were analyzed, and 77 were differentiated by their attenuated total reflection (ATR) spectra. Mineral grains may be mounted in oil for conventional polarized light microscope characterization and their ATR spectrum obtained with little or no interference by the liquid. This infrared microprobe method can be used to identify silicates, phosphates, nitrates, carbonates, and other covalent minerals; however, ionic minerals, metal oxide and sulfide minerals, and minerals with refractive indexes greater than diamond do not produce identifiable spectra, but the lack of a spectrum or one with high absorbance values does provide useful information. This research demonstrates the overall utility that infrared microprobe analysis brings mineral identification in soil evidence.     

印章防伪技术探析

印章防伪技术包括印痕防伪和印泥印油防伪,其中印泥印油防伪技术是印章防伪技术很重要的一个方面。目前在国内印泥印油防伪只限于荧光加密防伪,已不能从根本上达到防伪的目的。运用多色反光材料、有机物质和印泥,进行精工合成的新型防伪印泥以良好的性能保持印泥的本质不变,又能在印文中显现出不同颜色和不同大小的反光点,可以判断文件制成时间,有很好的防伪效果。     

显微红外光谱仪与显微拉曼光谱仪对纺用无色单根纤维的检测

目的研究常见纺用单根无色纤维的有效鉴别方法。方法使用显微红外光谱仪、显微激光拉曼光谱仪研究7大类纺用单根无色纤维的分子光谱。结果显微红外光谱仪、显微激光拉曼光谱仪能有效区分包括棉、粘胶、羊毛、丝、聚酰胺、聚丙烯腈和聚酯在内的7种纤维,是检测单根纤维的有效手段。785nm激发光源是显微激光拉曼光谱仪研究这7类纤维的最佳波长。但由于纺用纤维生产过程的标准化,仅依据红外或者拉曼的峰位置区分同种类、不同产地纤维的效果一般。结论显微红外光谱仪、显微激光拉曼光谱仪是鉴别常见纺用单根无色纤维的有效方法。     

显微红外光谱仪与显微拉曼光谱仪对纺用无色单根纤维的检测

目的研究常见纺用单根无色纤维的有效鉴别方法。方法使用显微红外光谱仪、显微激光拉曼光谱仪研究7大类纺用单根无色纤维的分子光谱。结果显微红外光谱仪、显微激光拉曼光谱仪能有效区分包括棉、粘胶、羊毛、丝、聚酰胺、聚丙烯腈和聚酯在内的7种纤维,是检测单根纤维的有效手段。785nm激发光源是显微激光拉曼光谱仪研究这7类纤维的最佳波长。但由于纺用纤维生产过程的标准化,仅依据红外或者拉曼的峰位置区分同种类、不同产地纤维的效果一般。结论显微红外光谱仪、显微激光拉曼光谱仪是鉴别常见纺用单根无色纤维的有效方法。     

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

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Detecting Gunshot Residue from Sellier & Bellot Nontox Heavy Metal‐free Primer by in situ Cathodoluminescence

Gunshot residue (GSR) from the discharge of ammunition can provide crucial information in reconstructing criminal cases. Traditional primers create particles of heavy metals such as lead, barium, and antimony. In forensic laboratories, automatic inorganic particle detection is performed by scanning electron microscopy (SEM), using the backscattered electron signal to search for bright residues among the many darker environmental particles, due to higher electron density of the former. Some innovative primers, indicated as heavy metal‐free (HMF), produce a residue of elements with atomic numbers below 21, urgently demanding new detecting solutions. For the first time, residues from Sellier & Bellot Nontox HMF primer are demonstrated to emit visible light under electron beam stimulation in a SEM. Cathodoluminescence is then proposed as a promising tool to both detect and characterize residues in forensic cases involving HMF primers, with minor changes to traditional analytical apparatus used for inorganic GSR analysis.