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.     

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.     

The Optimal Combination of Cartilage Source and Apparatus for Long‐Term In Vitro Chondrocyte Viability Analysis

Abstract: Most studies of long‐term chondrocytes survival were for tissue banks. They showed a gradual reduction in the viable chondrocytes percentage as a function of time and ambient temperature, but the samples were harvested under optimal conditions. The aim of our study was to determine the most reliable combination of cartilage source and assay for the in vitro postmortem chondrocyte viability analysis in the conditions that imitate a dead body. Osteochondral cylinders were procured from femoral condyles and talar trochleas of three male donors and stored in the cell culture media at 4 ± 2°C and 23 ± 2°C. The samples were analyzed by a cell viability analyzer and a confocal laser scanning microscope (CLSM) initially 24–36 h after death and then in 4‐week intervals. The results reconfirmed the significant influence of time (p = 0.0002), but not of the temperature (p = 0.237). The largest reproducibility was presented for the knee joint and the CLSM.     

Identification and comparison of electrical tapes using instrumental and statistical techniques: I. Microscopic surface texture and elemental composition

Comparisons of polyvinyl chloride electrical tape typically rely upon evaluating class characteristics such as physical dimensions, surface texture, and chemical composition. Given the various techniques that are available for this purpose, a comprehensive study has been undertaken to establish an optimal analytical scheme for electrical tape comparisons. Of equal importance is the development of a quantitative means for sample discrimination. In this study, 67 rolls of black electrical tape representing 34 different nominal brands were analyzed via scanning electron microscopy and energy dispersive spectroscopy. Differences in surface roughness, calendering marks, and filler particle size were readily apparent, including between some rolls of the same nominal brand. The relative amounts of magnesium, aluminum, silicon, sulfur, lead, chlorine, antimony, calcium, titanium, and zinc varied greatly between brands and, in some cases, could be linked to the year of manufacture. For the first time, quantitative differentiation of electrical tapes was achieved through multivariate statistical techniques, with 36 classes identified within the sample population. A single-blind study was also completed where questioned tape samples were correctly associated with known exemplars. Finally, two case studies are presented where tape recovered from an improvised explosive device is compared with tape recovered from a suspect.     

Interpretation of automotive light bulb examination results: an intriguing case

During the examination of light bulbs from a vehicle involved in a road accident, the headlights did not reveal any evidence regarding whether they were energized or not. Additionally, a police officer turned the lights on after the accident to verify their functioning, thus damaging some of the evidence. By examining the vehicle, it was determined that the park lights could provide answers regarding the conditions of the headlights. After observations, it was concluded that the park lights and headlights were off at the time of the impact. This case report demonstrates how important it is to integrate the circumstances surrounding the case into the interpretation of the results. Nevertheless, it also demonstrates the necessity for examining both the vehicle and all light bulbs in order to reach the most pertinent and proper conclusion.     

Application of 3D documentation and geometric reconstruction methods in traffic accident analysis: with high resolution surface scanning, radiological MSCT/MRI scanning and real data based animation

The examination of traffic accidents is daily routine in forensic medicine. An important question in the analysis of the victims of traffic accidents, for example in collisions between motor vehicles and pedestrians or cyclists, is the situation of the impact. Apart from forensic medical examinations (external examination and autopsy), three-dimensional technologies and methods are gaining importance in forensic investigations. Besides the post-mortem multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI) for the documentation and analysis of internal findings, highly precise 3D surface scanning is employed for the documentation of the external body findings and of injury-inflicting instruments. The correlation of injuries of the body to the injury-inflicting object and the accident mechanism are of great importance. The applied methods include documentation of the external and internal body and the involved vehicles and inflicting tools as well as the analysis of the acquired data. The body surface and the accident vehicles with their damages were digitized by 3D surface scanning. For the internal findings of the body, post-mortem MSCT and MRI were used. The analysis included the processing of the obtained data to 3D models, determination of the driving direction of the vehicle, correlation of injuries to the vehicle damages, geometric determination of the impact situation and evaluation of further findings of the accident. In the following article, the benefits of the 3D documentation and computer-assisted, drawn-to-scale 3D comparisons of the relevant injuries with the damages to the vehicle in the analysis of the course of accidents, especially with regard to the impact situation, are shown on two examined cases.     

差示扫描量热法检验猎枪弹丸

目的对不同厂家的猎枪弹丸进行区分和鉴别。方法使用功率补偿型差示扫描量热仪(DSC)对4种不同品牌的猎枪弹丸进行分析。结果可测得每种弹丸的DSC曲线和熔点温度Tm,熔融峰温Tmp,熔化焓ΔHm等热学参数。结论利用差示扫描量热法可以对不同品牌的猎枪弹丸进行鉴别,该方法为办案过程中遇到同号数不同品牌的猎枪弹丸鉴别提供了一种有效技术手段。     

表象训练提高运动技能效能的心理机制

表象训练已被证明是行之有效的运动技能训练辅助手段,但现有研究仍然集中在训练的有效性验证方面,其心理机制的研究相对较少.认知心理学关于表象的实验研究揭示了表象训练的心理机制在于:表象是表象训练的素材,为运动技能训练获得了形象与抽象的双重调控;表象提供了运动技能心理训练的基本模式,为运动技能的创新准备了基本条件.     

试论国际环境法的共同但有区别的责任原则

共同但有区别的责任原则主要包涵两层意思:共同责任和区别责任。但共同责任和区别责任是一个不可分割的有机联系的统一整体,并分别具有丰富的内涵。确立共同但有区别的责任原则是国际环境保护事业的历史发展所使然。由于该原则体现了发展中国家维护自身权益和平等地参与国际谈判以解决全球环境问题的意愿,故而其对发展中国家具有较强的亲和力。该原则具有很强的实践品格,其适用范围主要局限于环境保护领域。它是正在形成和发展中的国际环境法的基本原则,也许在不远的将来能获得国际习惯法的法律地位和效力。     

浅析端口入侵行为及其防范

目前 ,网络犯罪已成为严重的社会问题。防范和打击计算机犯罪是新时期公安机关的重要工作。本文通过对计算机端口通讯方式和端口扫描方式的介绍 ,分析了计算机端口的常见入侵方式 ,并简要总结了防范计算机端口入侵的技术措施。