From clean spaces to crime scenes: Exploring trace DNA recovery from titania-coated self-cleaning substrates

Titanium dioxide (titania, TiO₂) is frequently used as a coating for a variety of self-cleaning products, such as antifogging vehicle mirrors, ceramic tiles, and glass windows because of its distinct physiochemical features. When exposed to light TiO₂ causes photocatalytic decomposition of organic contaminants, potentially compromising DNA integrity. The impact of TiO₂-coated commercial glasses, Bioclean® and SaniTise™, on trace DNA persistence, recovery, and profiling was investigated. DNA in saliva and touch samples deposited on self-cleaning glass slides exposed to indoor fluorescent light for up to seven days was more degraded than control samples indicating some degree of fluorescent light-induced photocatalytic activity of the self-cleaning surfaces. When exposed to sunlight, DNA yields from saliva and touch samples deposited on the titania-coated substrates decreased rapidly, with a corresponding increase in DNA degradation. After three days no DNA samples applied to self-cleaning glass and exposed to natural sunlight yielded STR profiles. These results suggest that the photocatalytic activation of TiO₂ is the likely mechanism of action underlying the extreme DNA degradation on the Bioclean® and SaniTise™ glasses. Consequently, rapid sample collection and use may be warranted in casework scenarios involving TiO₂-coated materials.     

Latent Fingermark Aging Patterns (Part IV): Ridge Width as One Indicator of Degradation

This fourth article of the series is taking an in‐depth analysis at the visible aging of latent fingermarks regarding changes in ridge widths over time. The objective is to quantify and statistically describe significant ridge size variations under controlled indoor conditions. The effect of three environmental variables are examined: type of secretion (sebaceous‐ and eccrine‐rich) and type of substrate (glass and polystyrene) when aged in three light conditions (direct natural light, shade, and dark). Prior to width measurements, fresh and aged fingermarks were powdered with titanium dioxide (TiO₂) and sequentially photographed at predetermined times over 6 months. Three independent observers measured the ridges from thirty predetermined locations using strategically placed intersecting lines on the print. Results indicate that fingermarks deposited on glass are more resilient to degradation compared with those deposited on plastic. The presence of direct natural light plays a negligible role on degradation compared to secretion and substrate types.     

Trace Elemental Analysis of Titanium Dioxide Pigments and Automotive White Paint Fragments for Forensic Examination Using High‐Energy Synchrotron Radiation X‐Ray Fluorescence Spectrometry*

Abstract: High‐energy synchrotron radiation x‐ray fluorescence spectrometry (SR‐XRF) utilizing 116 keV x‐rays was used to characterize titanium dioxide pigments (rutile) and automotive white paint fragments for forensic examination. The technique allowed analysis of K lines of 9 trace elements in 18 titanium dioxide pigments (rutile), and 10 trace elements in finish coat layers of seven automotive white paint fragments. High‐field strength elements (HFSE) were found to strongly reflect the origin of the titanium dioxide (TiO₂) pigments, and could be used as effective parameters for discrimination and classification of the pigments and paint fragments. A pairwise comparison of the finish coat layers of seven automotive white paint fragments was performed. The trace elements in the finish coat layers detected by the high‐energy SR‐XRF were especially effective for identification. By introducing the trace element information of primer and electrocoat layers, all the automotive white paint fragments could be discriminated by this technique.     

传统硫熏加工与现代微波加工滁菊质量比较

目的 通过对硫熏加工滁菊和微波加工滁菊中主要化学成分进行比较,为滁菊的合理加工方法提供依据.方法 以挥发油、总黄酮、绿原酸及二氧化硫残留量为检测指标,对两种方法加工的滁菊的主要化学成分进行比较分析.结果 硫熏滁菊中挥发油、绿原酸含量均高于微波滁菊;硫熏滁菊中总黄酮的含量略低于微波滁菊;硫熏滁菊的薄层色谱斑点数与微波滁菊...     

The causes of death in fire victims

In 169 consecutive cases of autopsied fire victims about 50% had lethal levels of carboxyhemoglobin. Soot in the respiratory tract was found in about 90% of the cases. The age distribution of the fire victims showed significantly less persons in the 15-35-year group than should be expected according to the age distribution of the population, presumably due to greater agility of younger people. More than half of the fire victims had alcohol in the blood exceeding 0.05%, and alcohol intoxication should be considered accessary to many deaths in fire. The characteristic biphasic distribution of carboxyhemoglobin in fire victims together with other observations suggest that the principal causes of death are carbon monoxide followed by carbon dioxide poisoning and/or oxygen deficiency, while the influence of heat is considered to be of minor importance.     

Latent Fingermark Aging Patterns (Part I): Minutiae Count as One Indicator of Degradation

The authors are exploring degradation patterns of latent fingermarks over time which can be quantitatively determined in a predictable manner by visual means. Several physical degradation parameters for assessing this hypothesis are evaluated. This article analyzes the parameter “minutiae count” as a function of time. Experiment variables included were secretion type (sebaceous‐rich and eccrine‐rich), substrate (glass and plastic), and exposure to light (dark, shade, and direct light). Depositions were sequentially visualized with Titanium Dioxide powder over a period of 6 months, photographed, and number of minutiae recorded. Results revealed a significant decrease of minutiae for eccrine‐rich marks on glass but insignificant for sebaceous‐rich marks on the same surface. However, significant degradation was observed for both types of secretions on plastic. The authors conclude that the distinctive prevalence of minutiae changes over time indicates with a high degree of certainty the hypothesis is valid and deserves additional exploration.     

A Fatal Case of CO2 Intoxication in a Fermentation Tank

Carbon dioxide (CO₂) is an odorless constituent of air. Higher concentrations can be detected in geothermal and automotive emissions, fermentation, and sublimation of dry ice. An unskilled worker entered a fermentation tank to clean it, which had not been done for about 5 months allowing for high concentrations of CO₂ to build up. A second worker entered the tank to rescue the first one. Shortly after both were found the first worker was rescued directly whereas the tank had to be rotated to pull the second worker out. Cardiopulmonary resuscitation was successful only for the first worker. Medico‐legal autopsy showed bruises, hematoma, myocardial hemorrhage, and edema of the lungs. The right lung was vacuum degassed in an argon atmosphere and quadrupole‐mass‐spectrometry showed an elevated CO₂ content in lung gases. Thus, CO₂ intoxication/asphyxia in a vitiated atmosphere due to fermentation of wine mash was established as the cause of death.     

从威权管制到社会治理——关于修订《大气污染防治法》的几点思考

我国《大气污染防治法》的修订正在进行之中,大气污染防治法的修订,仍存在一些有待解决的重大问题。除了基于气候变化问题对二氧化碳的规制作出回应,以及结合我国大气污染现状提出大气污染防治应引入分区管理制度外,现行《大气污染防治法》仍然呈现出以政府为主体,以污染企业为规制对象的单一化威权体制特征,其法律实施效果不佳,也不符合现代社会自我管制与和谐发展的要求。为此,需要加强市场激励机制的作用,为社会自我管制和公众参与提供条件,并基于行政责任和民事责任动因的不同,改变目前法律责任规定中重行政责任轻民事责任的现状。     

A Carbon Dioxide Fatality from Dry Ice

Abstract:  This report documents a rare case of carbon dioxide intoxication in a young healthy male. The deceased hid in a small plastic container, size 1.5 × 1 × 1 m, and within 5 min he was located suffering convulsions and was reported as dead within minutes. Scene investigation revealed dry ice in the container. Autopsy findings were unremarkable. The probable cause of the convulsions was carbon dioxide intoxication due to both the dry ice sublimation and the small confined space in which he was hiding. This report emphasizes the significance of scene investigation in establishing the cause of the death.