Electrical Pulse Generated Upon Discharging a Firearm and Its Implication for Gunshot Residue Analysis

Ammunition primers consisting of a mixture of lead styphnate, barium nitrate, and antimony (III) sulfide, upon deflagration, lead to the formation of inorganic gunshot residue (GSR). The cations, from their predeflagration form, undergo reduction reactions during burning to form the classic spheroidal, micron-sized particles indicative of GSR. However, the rapidly changing pressure and temperature of the reaction zone implies that the reactions cannot go to completion. In this study, we use a conductivity detector to show that GSR produces an electrical pulse which corroborates the incomplete redox chemistry. We find that the shape of some GSR formed in an electric field also suggests its nonneutral character. Tantalizingly, the formation of GSR might be a result of Coulombic repulsion shattering the molten droplets in to smaller spheroids. Lastly, we suggest that deposition or transfer of GSR could be influenced by static electricity, an area which should be further studied.     

测谎检验的证明价值与法律控制要件探析——以民事诉讼为视角

民事案情纷繁复杂,有时难以甄别理清,探索完善有助于发现事实的新科学证据方法无疑是一种有益进路。测谎检验的适用尽管在国际与国内均存在肯定说与否定说之争,但其作为诉讼中探寻案件真相的新兴技术手段仍引起了各界的不断关注。相较于传统质证方法,测谎检验意见作为一种通过特殊物质化手段获取的关于案件知情人所述言词内容的真实性判断,具有客观性、科学性的优势,其更易排除主观因素的干扰,应作为证据的一种,具有一定的证明价值。通过对测谎检验技术对于真相证明意义的探讨,更关注对这种新技术的合理司法控制,拟通过证明评价僵局原则、当事人意愿原则、事实设问中的集中性原则、证据链形成原则等四个方面分析测谎检验的法律控制标准,规范该鉴定技术的适用,使测谎检验能够在民事诉讼的正轨中有序运行、健康成长。     

一种水下金属物证探测器的设计

目的 设计一种水下金属物证探测器,用于公安人员在池塘、沟渠、水井等水域中搜寻金属类物证.方法 采用金属探测技术、水下视频采集技术和无线传输技术相结合,实现探测器的多功能特性.结果 在深度不超过4m的水域中,借助探测器可以准确搜寻到金属物证.结论 该探测器具有金属探测以及视频图像采集、无线发送和保存的功能,能满足一定范围内搜寻水下金属物证的工作需求.     

对纤维蛋白诊断生前伤的评价——45例枪弹创组织的MSB染色和扫描电镜对比观察

生活反应是诊断生前伤的主要根据.近二十年来,法医病理学在研究生前伤和死后伤的诊断中,采用了多种新兴技术,如扫描电镜技术、酶组织化学技术、酶标技术、电泳技术等,促使生前伤的诊断水平有明显提高.伤后存活1小时死亡者,大部分皆可获得明确诊断;立即死亡或在濒死期形成的损伤,由于生活反应甚微,或受腐败等     

屠宰猪肝和血清中乙型肝炎病毒及戊型肝炎病毒的检测

应用1对乙型肝炎病毒(HBV)S基因保守区的引物,采用PCR方法从屠宰猪肝、血清中检测到了HBV,序列分析表明,扩增片段与已发表的HBV S基因的同源性高达98%~100%。电镜负染色样品观察结果表明,在HBV表面抗原ELISA检测强阳性反应的血清样品中存在有形态、大小与人HBV Dane颗粒和小球状颗粒相似的病毒粒子。针对戊型肝炎病毒(HEV)ORF2/ORF3重叠区设计了简并引物,采用巢式RT-PCR对屠宰猪肝和血清样品进行了检测。结果表明,部分屠宰猪肝中存在HEV。     

电子政务在政府管理创新中的实现途径

充分发挥电子政务在政府管理创新中的作用,必须加强电子政务工作领导,合理设计电子政务的建设目标,健全相关工作机构,整合人才资源,提供资金保障.     

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.     

数码照相机与视频荧光鉴别仪的物证检验应用比较

索尼SONY WVC-CD300数码照相机与SYJ-5型视频荧光鉴别仪应用在文件检验时,视频荧光鉴别仪部分功能可用 该种数码照相机代替,各具特色。     

Accumulation of explosives in hair--Part 3: Binding site study

This study extends previous work on the sorption of explosives to the hair matrix. Specifically, we have studied the interaction of 2,4,6-trinitrotoluene (TNT) and triacetone triperoxide (TATP) as a function of chemical pretreatment with acetonitrile, neutral and alkaline hydrogen peroxide, methanolic KOH and potassium permanganate, and the morphological changes that accompany these treatments. While differences in vapor pressure can account for quantitative differences between TNT and TATP sorption, both are markedly affected by the chemical rinses. Examination of the hair surface shows different degrees of smoothening following rinsing, suggesting that the attachment to hair is largely a surface phenomenon involving the 18-methyleicosanoic acid lipid layer. Density functional theory calculations were employed to explore possible nucleation sites of TATP microcrystals on the hair. We conclude that some of the sites on melanin granular surfaces may support nucleation of TATP microcrystals. Moreover, the calculations support the experimental finding that dark hair adsorbs explosives better than light hair.     

人为删改和破坏的硬盘数据的恢复

随着信息产业的高速发展,计算机的应用已变得越来越普遍。传统的纸张存储信息的方式也被计算机存储所替代。而信息技术本身是一项非常前沿的技术,计算机存储数据的安全性也就很难保证的。通过人为的删改和破坏数据来销毁证据的案例屡屡发生。这也就对公安工作提出了新的挑战。被修改和破坏了的数据统称损坏数据。目前,数据存储体被损坏的类型主要有软损坏和硬损坏。本文针对这两个方面在数据存储原理、恢复原理、恢复方法等内容上进行了深入的探讨。