Enhancement of ninhydrin- or DFO-treated latent fingerprints on thermal paper

A new method for enhancement of ninhydrin or 1,8-diazafluoren-9-one (DFO)-treated latent fingerprints on thermal paper will be described. Most thermosensitive surfaces of thermal paper become dark when treated with DFO or ninhydrin petroleum ether (NPB) solution. This effect minimizes contrast between the developed fingerprints and the background. The new method described reduces this dark staining without removing the thermosensitive layer and parts of the developed fingerprints, as occurs with acetone washing. Through the new method, the developed fingerprints appear in sharp lines and high contrast. Extensive tests were performed, leading to an optimized working solution, which charges the paper with a minimum of chemicals, is cheap, and enables a large quantity of papers to be treated in a short time. The working solution contains commercially available, nonvolatile, nitrogenous organic compounds and can be used like the application of NPB solution by dipping.     

家兔烧死后气管、肺及心肌的病理形态学观察

目的探讨烧死的病理形态学依据。方法建立家兔烧死动物模型,用光镜、透射及扫描电镜观察10只生前烧死家兔气管、肺及心肌的病变;并与死后焚尸及非烧死的正常组(各5只)对照。结果透射电镜下,气管粘膜上皮完全脱落,成堆红细胞和纤维蛋白成分粘附在平滑肌表面。肺Ⅰ型上皮细胞结构基本完整连续,线粒体嵴有断裂、缺失;Ⅱ型肺泡上皮细胞微绒毛消失,多数细胞线粒体、板层小体、高尔基体未见异常,少数Ⅱ型肺泡上皮细胞质膜破损、染色质浓集、胞质内容丢失。心肌严重变性坏死,细胞膜破坏,线粒体极度肿胀,肌丝溶解并出现收缩带坏死。扫描电镜下,气管粘膜上皮有完整纤毛,但上皮大片脱落,少数区域纤毛上皮稀疏排列,有脱落柱状上皮附着在纤毛上;肺间皮细胞结构基本完整,微绒毛数量不一致;心内膜的内皮细胞大部脱落,暴露内皮下结缔组织,心肌纤维呈扭曲排列。死后焚尸及正常组对照组未见上述变化。结论烧死兔的光镜和电镜下气管、肺及心肌的病理形态学变化,能为生前烧死与死后焚尸的鉴别提供依据。     

差示扫描量热法（DSC）检验塑料绳

目的:对不同厂家的塑料绳进行区分和鉴别。方法:使用功率补偿型差示扫描量热仪(DSC)对五种不同厂家的塑料绳进行分析。结果:可测得每种塑料绳的DSC曲线和熔点温度Tm,熔融峰温Tmp,熔化焓△Hm等热学参数。结论:利用差示扫描量热法可以对型号和颜色相同而厂家不同的塑料绳进行鉴别,该方法为办案过程中塑料绳的检验提供了一种有效技术手段。     

DMAC显现化学类纸张上汗潜手印的方法

目的找到一种显现化学类纸张上汗潜手印的有效方法。方法制作DMAC显现试剂并进行大量比对实验、外延实验。结论用该方法操作简便、效果较好。     

Visualization of Fingermarks Deposits on Untreated Thermal Paper Exploiting the Near Infrared Luminescence

Thermal paper is widely used as a print medium for different applications but it constitutes a tricky substrate for fingermark visualization. An earlier work (J Forensic Sci 2015; 60 :1034) reported how to visualize fingermarks on untreated thermal paper by illuminating the item with a UV-A light source. In the present paper, the potential of the near infrared (NIR) luminescence has been tested on thermal paper compared to the mentioned method. A controlled study was carried out utilizing eccrine enriched fingermarks. The promising outcomes obtained were further confirmed by performing a pseudo-operational trial. Data clearly showed that the use of the NIR filter gave better results. Finally, preliminary tests suggested a different mechanism of reaction induced by fingermarks with respect to the one behind the thermal printing. Thus, NIR luminescence represents a refinement to the suite of optical examination processes, including the potential to increase the number of marks recovered in a noncontact, nondestructive way.     

DFO／PVP试剂显现热敏纸上汗潜指纹方法研究

目的建立热敏纸上汗潜手印显现的新方法。方法根据DFO／PVP溶液能够阻碍热敏纸的显色,能够和手印遗留物质中的氨基酸发生显色反应的原理来显现手印。结果PVP浓度为5％、7．5％、10％时,荧光效果较好;DFO／PVP试剂显现热敏纸上汗潜指纹不会导致背景变黑;DFO／PVP试剂在热敏纸上的显现效果优于DFO试剂;对遗留时间为154天的ATM机上一枚凭证显出了清晰的指纹纹线。结论DFO／PVP显现法操作简单、安全可靠、显出率高、荧光强。     

Improvement in Latent Fingerprint Detection on Thermal Paper Using a One‐Step Ninhydrin Treatment with Polyvinylpyrrolidones (PVP)

Abstract: Most thermosensitive surfaces of thermal paper turn black when they come into contact with polar organic solvents such as are used in ninhydrin petroleum benzin solution. This dark staining reduces the contrast between the developed fingerprint and the background to such an extent that the identification process becomes very difficult. Integrating polyvinylpyrrolidones (PVP) into a ninhydrin solution prevents the black staining, and the developed fingerprints appear in clear contrast to the background. The new ninhydrin solution containing PVP is successful compared to the two‐step ninhydrin–acetone washing method for thermal paper which is popular in Germany.     

Visualizing Indented Writing on Thermal Paper by the Controlled Application of Heat

Indented writing on thermal paper made with either one, two, or three sheets of paper above the thermal paper has been visualized by the controlled application of heat to the thermal paper at temperatures below the paper's normal color change temperature. Indentations created by applying a variable pressure to a steel letter stamp showed that, with one sheet above the thermal paper, indentations were more visible at lower pressures than with either two or three sheets above. Handwriting from 20 volunteers produced indented writing graded with most of the text clear and easy to read for all samples with one sheet above, half the samples with two sheets above and eight samples with three sheets above. Comparison with ESDA showed that, with three sheets above, there was a statistically significant difference (p < 0.01), with heating producing more samples than ESDA with most of the text clear and easy to read.     

Hyperthermia,Thermal Injuries,and Death from a Forced Convection Heat Source: A Case Report and Experimental Model

Heat‐related deaths of children are most often encountered in the context of enclosed vehicles in summer months. Deviating from this, a 16‐month‐old boy was found unresponsive in a stroller that was placed adjacent to a space heater during mid‐winter. The cause of death was hyperthermia and thermal injuries. Manner of death determination was difficult due to alleged surrounding circumstances. To understand the time‐course of this child's injuries, a child death scene investigation was performed; the stroller and space heater were recovered. In a re‐enactment of the events, a slaughtered pig approximating the child's size was warmed using a water bath and placed in the stroller beside the space heater. Cutaneous temperature measurements showed rapid initial temperature rise with subsequent steady increases. Tanning of the skin was seen on periodic direct observations. Internal temperature monitoring illustrated steady increases. This experiment was essential in classifying the manner of death as homicide.     

Temperature fluctuations at sympathetic preganglionic neuron sites in the thoracolumbar section of the spinal column as cues to deception: a preliminary study

In this experiment, both thermal imaging and the Concealed Information Test (CIT) methodologies were adopted, for the first time, to explore the efficacy of the thermal imaging of the thoracolumbar (T1–L3) region of the spinal column within the context of deception detection. Thirty-one participants followed a CIT-based structured interview process in a low-stakes laboratory setting whereby temperature fluctuations induced by the preganglionic neurons in the spinal column were measured with a thermal imaging camera during verbal responses to interview questions. The degree of temperature changes was then analyzed in order to determine truthfulness and deceit. Thermal imaging of the thoracolumbar region of the spinal column during sympathetic activation was effective in determining truthful responses with an accuracy rate of 91.9% and deceitful responses with an accuracy rate of 71.0%. Current findings support the potential use of temperature fluctuations of preganglionic neuron sites in the thoracolumbar section for lie-detection purposes.