激光共聚焦拉曼光谱技术在烟火药检验中的应用

目的建立微量烟火药的无损检验方法。方法利用激光共聚焦拉曼光谱技术对烟火药进行检验。结果烟火药的不同组分具有不同的拉曼特征散射峰。结论利用激光共聚焦拉曼光谱技术可以对烟火药中的不同组分进行检验,通过成像技术可得到不同组分的分布信息,该方法具有检验灵敏度高、无需样品制备、无损检材等优点。     

光谱成像检验同种同色涂抹掩盖字迹研究

目的建立一种无损、灵敏、直观的同种同色涂抹掩盖字迹的显现方法。方法依据涂抹掩盖字迹油墨物质的同色异谱特征,利用可见光滤波型多光谱成像检验系统进行检验。结果黑色圆珠笔、蓝色圆珠笔、黑色签字笔和蓝色签字笔相互涂抹掩盖形成的同种同色涂抹掩盖样本,利用可见光滤波型多光谱成像检验系统进行检验,显效率分别为90.5%、69.1%、49.5%、78.6%,显现效果良好。结论多光谱成像技术可以显现同种同色涂抹掩盖字迹,且具有良好的显现效果。     

显微光谱成像技术在汽车油漆截面检验中的应用

目的对汽车多层油漆的横截面进行分层和比对研究。方法运用显微光谱成像技术对收集的12个省市623个汽车漆片样本进行分层,并对截面结构相同或相似的油漆样本进行了区分。结果 623个油漆样本均可以分层,分析出漆层为两层及以上的油漆样本数占总数的87.26%;截面结构相同或相似的油漆样本能够多层同时区分。结论该方法具有科学及实用价值,检验结果可靠,可见光谱成像技术完全可运用拓展到微量物证的检验中。     

Visualization of Latent Blood Stains Using Visible Reflectance Hyperspectral Imaging and Chemometrics

The detection of latent traces is an important aspect of crime scene investigation. Blood stains on black backgrounds can be visualized using chemiluminescence, which is invasive and requires a darkened room, or near-infrared photography, for which investigators need to change filters manually to optimize contrast. We demonstrated the performance of visible reflectance hyperspectral imaging (400–720 nm) for this purpose. Several processing methods were evaluated: single wavelength bands, ratio images, principal component analysis (PCA), and “SIMPLe-to-use Interactive Self-modeling Mixture Analysis” (SIMPLISMA). Using these methods, we were able to enhance the contrast between blood stains and 12 different fabrics. On black cotton, blood dilutions were visible with a minimal concentration of 25% of whole blood. The hyperspectral camera system used in this study is portable and wireless, which makes it suitable for crime scene use. The described technique is noncontact and nondestructive, so all traces are preserved for further analysis.     

Evaluation of photometric stereo and elastomeric sensor imaging for the non-destructive 3D analysis of questioned documents – A pilot study

Photometric Stereo and Elastomeric Sensor Imaging were assessed for measuring the 3-dimensional (3D) morphology of questioned document samples. Photometric stereo is shown to be a powerful non-contact technique for revealing micron level detail of the samples examined. Elastomeric Sensor Imaging is shown to complement photometric stereo by yielding equivalent results. Additionally, this technique allows quantification of the morphological depth information. The techniques were applied to 2 different types of questioned document sample. Firstly, written signatures were examined. Both techniques were able to reveal characteristic features that could be used to infer stroke direction and ink line application sequence. Secondly toner/ink intersections were examined. Both techniques allowed visualisation of 3D features which were used to infer the sequence of application.     

The Effect of Skin Debris on Gunshot Residue Sampling and Detection

These experiments were designed to determine whether skin debris (desquamated epithelial cells and apparent skin oils) affects gunshot residue (GSR) particle detection on the sticky tape lift samples prepared for scanning electron microscopy (SEM). A dabbing experiment showed that GSR particles accumulate not only on the adhesive surface of the sampler, but also on the epithelial cell surfaces. Samplers were loaded with target GSR followed by dabbing 30 times on the back of a hand. Backscatter electron images were taken at 20 kV and for some at 30 kV of the same areas. The samplers were then treated with a sodium/calcium hypochlorite solution (bleach) to remove skin debris and again imaged in the SEM. Comparison of these images shows more GSR particles will likely be revealed at 30 kV than 20 kV and more particles revealed by the bleach treatment in an automated SEM system.     

If Brain Scans Really Detected Deception,Who Would Volunteer to be Scanned?

Abstract: Recent neuroimaging studies investigating the neural correlates of deception among healthy people, have raised the possibility that such methods may eventually be applied during legal proceedings. Were this so, who would volunteer to be scanned? We report a “natural experiment” casting some light upon this question. Following broadcast of a television series describing our team’s investigative neuroimaging of deception in 2007, we received unsolicited (public) correspondence for 12 months. Using a customized template to examine this material, three independent assessors unanimously rated 30 of an initial 56 communications as unequivocally constituting requests for a “scan” (to demonstrate their author’s “innocence”). Compared with the rest, these index communications were more likely to originate from incarcerated males, who were also more likely to engage in further correspondence. Hence, in conclusion, if neuroimaging were to become an acceptable means of demonstrating innocence then incarcerated males may well constitute those volunteering for such investigation.     

人与狗、猪、牛、羊长骨哈氏系统图像分析的比较

目的探讨人与狗、猪、牛、羊长骨的哈氏系统的形态特点、图像分析特点及其鉴别要点。方法制作人与狗、猪、牛、羊长骨中段横切磨片35张,光镜下观察比较哈氏系统,并在研究型显微镜下进行图像分析。结果人骨无丛状骨和骨单位带;人与狗、猪、牛、羊骨的哈氏系统在形状、大小、分布位置、均匀程度等方面存在明显差异;人骨哈佛骨板层数最多,哈氏系统直径最大;中央管直径和面积百分比的图像分析结果显示人与动物骨的差异均有显著意义。结论(1)丛状骨、骨单位带在种属鉴定中可作为人骨的排除指标;(2)人骨与狗、猪、牛、羊骨在哈氏系统结构方面有明显区别;(3)利用图像分析进行种属鉴定,中央管面积百分比是区别人骨与动物骨的重要参考指标。     

放射影像学在颈部损伤尸体检验中的应用

多层面计算机断层成像(MSCT)和磁共振成像(MRI)对尸体骨骼系统和软组织损伤的诊断价值等同于传统的尸体解剖,运用在颈部损伤的尸体检验中可以弥补传统尸体解剖的某些不足,在某些特定的环境、腐败、烧焦或具有传染性的尸体检验中,MSCT和MRI联合使用可以作为机械性窒息、挥鞭样损伤、颈椎损伤及颈部血管损伤的可选择的法医学检查手段之一。     

膝关节侧副韧带损伤MRI影像诊断的比较研究

目的研究膝关节侧副韧带损伤的MRI诊断与法医学鉴定意义。方法对经手术或临床证实的11例共13条损伤的侧副韧带与12例正常膝关节进行回顾性MRI对比研究。结果正常胫、腓侧副韧带在T1WI和T2WI上均呈扁平条状低信号结构,平均长度分别为6.8cm和5.7cm;13条侧副韧带损伤,单纯胫侧副韧带损伤6条,单纯腓侧副韧带损伤3条,两侧侧副韧带同时损伤2例4条;其中I级侧副韧带损伤5条,II级侧副韧带损伤5条;III级侧副韧带损伤3条;7例(63.6%)出现并发症,其中前交叉韧带损伤3条,后交叉韧带损伤4条,半月板损伤2个。结论MRI能清晰显示膝关节侧副韧带解剖结构,能准确诊断侧副韧带损伤并进行分级,还能发现多种并发症,对法医学鉴定有重要意义。