Preparation of a Ytterbium‐tagged Gunshot Residue Standard for Quality Control in the Forensic Analysis of GSR

Preparation of a ytterbium‐tagged gunshot residue (GSR) reference standard for scanning electron microscopy and energy dispersive X‐ray spectroscopic (SEM‐EDS) microanalysis is reported. Two different chemical markers, ytterbium and neodymium, were evaluated by spiking the primers of 38 Special ammunition cartridges (no propellant, no projectile) and discharging them onto 12.7 mm diameter aluminum SEM pin stubs. Following SEM‐EDS microanalysis, the majority of tri‐component particles containing lead, barium, and antimony (PbBaSb) were successfully tagged with the chemical marker. Results demonstrate a primer spiked with 0.75% weight percent of ytterbium nitrate affords PbBaSb particles characteristic of GSR with a ytterbium inclusion efficiency of between 77% and 100%. Reproducibility of the method was verified, and durability of the ytterbium‐tagged tri‐component particles under repeated SEM‐EDS analysis was also tested. The ytterbium‐tagged PbBaSb particles impart synthetic traceability to a GSR reference standard and are suitable for analysis alongside case work samples, as a positive control for quality assurance purposes.     

Powdered Activated Carbon: An Alternative Approach to Genomic DNA Purification

Forensic evidence samples are routinely found as stains on various substrates, which may contain substances known to inhibit polymerase chain reaction (PCR). The goal of this study was to evaluate post‐Chelex^®100 purification using powdered activated carbon (PAC). Mock crime scene DNA extracts were analyzed using quantitative PCR and short tandem repeat (STR) profiling to test the DNA recovery and inhibitor removal using PAC with those of the Amicon^®Ultra 100K. For extracted bloodstains on soil and wood substrates, PAC and Amicon^®Ultra 100K generated similar DNA yield and quality. Moreover, the two methods significantly decreased the concentration of humic substances and tannins compared to nonpurified extracts (p < 0.001). In instances where extracts contained indigo dye (bloodstains on denim), Amicon^®Ultra 100K performed better than PAC due to improved amplifiability. Efficient adsorption of humic substances and tannins, which are common inhibitors, indicates PAC's potential application in the purification of high‐template DNA extracts.     

Study of the Behaviors of Gunshot Residues from Spent Cartridges by Headspace Solid‐Phase Microextraction–Gas Chromatographic Techniques

Gunshot residues, produced after shooting activity, have acquired their importance in analysis due to the notoriety of firearms‐related crimes. In this study, solid‐phase microextraction was performed to extract the headspace composition of spent cartridges using 85‐μm polyacrylate fiber at 66°C for 21 min. Organic compounds, that is, naphthalene, 2,6‐dinitrotoluene, 2,4‐dinitrotoluene, diphenylamine, and dibutyl phthalate were detected and analyzed by gas chromatography‐flame ionization detection technique. Evaluation of chromatograms for diphenylamine, dibutyl phthalate, and naphthalene indicates the period after a gunshot was discharged, whether it was 1 days, 2–4 days, <5 days, 10 days, 20 days, or more than 30 days ago. This study revealed the potential effects of environmental factors such as occasional wind blow and direct sunlight on the estimation of time after spent cartridges were discharged. In conclusion, we proposed reliable alternative in analyzing the headspace composition of spent cartridges in a simulated crime scene.     

Sectoral Opposition to Carbon Taxes in the EU – a Myopic Economic Approach

Over 10 years ago the EU Commission proposed a directive on carbon taxes, but faced so much domestic resistance that agreement was not reached until last year – and after it had been considerably watered down. The aim of this paper is to look into economic reasons for the political infeasibility of extensive carbon taxes. Since opposition is believed to arise prior to the policy implementation, the cost estimates have a myopic character compared with market estimates, in the sense that sectors are presumed to take into account their own substitution opportunities, but disregard changes in other sectors as well as the macroeconomic welfare gains from a tax regime. With this myopic approach, we estimate and compare costs of emissions cuts across sectors and across countries in the EU, showing how different sectors might have anticipated the impacts from an expected carbon tax. This focus illustrates that what seems to be cost-effective and to the best for the region on paper turned out too controversial to be politically feasible.     

Evidence of Premeditation in Skin Messages in Suicide

A 34‐year‐old man with manic‐depressive disorder was found dead sitting in a vehicle with a hose running from the exhaust pipe to the cabin. Numerous suicide notes were found inside his house. At autopsy, the decedent was wearing jeans and a long‐sleeved windcheater. Upon removal of his clothes, a series of messages were also found written on the legs and forearm. Death was due to carbon monoxide toxicity with a blood level of carboxyhemoglobin of 84%. Skin messages represent a rare form of suicide note that may suggest that a suicide has not been planned, as the decedent may have used the nearest surface to write on. This case demonstrates, however, that skin messages may be more organized, being written prior to dressing and setting up the fatal episode. They also may compliment other notes and messages.     

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.     

One global deal from Paris 2015: Convergence and contestations on the future climate mitigation agenda

This article analyses the 2015 Paris Agreement of the UN Framework Convention on Climate Change, with a focus on mitigation. The history of climate negotiations and the mitigation agenda shows the divide between developed and developing countries, with the latter insisting that the former, having caused the problem, need to do more to reduce carbon emissions to address climate change. However, as some emerging economies had continued to emit more carbon, there were calls to treat these as developed countries, requiring increased mitigation measures. The article examines the record of these emerging economies, and establishes that there was some convergence in Paris, a positive element that resulted in a single global climate treaty. However, the Paris negotiations also witnessed contestations, with the final agreement insufficient to keep global warming within advised limits, and in any case only partly legally binding, leaving its implementation success to good will.     

A study of dispersion of gunshot residue from a frequently used Serbian ammunition cal. 7.65 mm to support selected aspects of casework in North Macedonia

The subject of this research was the inorganic gunshot residue component collected from shooting patterns obtained on woven cotton cloth using a Pietro Beretta model 70 pistol, cal. 7.65 mm and Serbian ammunition for the following muzzle-to-target distances: 25, 50, 75, 100 and 125 cm. For each distance, three rounds of shooting were performed. Particles were lifted within a 10 cm radius of the projectile entrance and automatically analyzed using a scanning electron microscope coupled with an energy dispersion X-ray spectrometry. The obtained data on the populations of particles were analyzed taking into account their numbers, chemical classes and sizes. The results showed an apparent maximum incidence within all particles containing barium at about 50 cm distance. Also, lead particles revealed a distinct behaviour, being dominant at a 25 cm distance, falling below the other chemical classes, and finally becoming dominant again at 125 cm. The analysis of the frequency of occurrence of particles sorted according to their sizes confirmed that the small particle population is the largest, and their distribution in function of the equivalent circle diameter is exponential-like. The obtained results provided knowledge on the distribution of particles in the vicinity of the tested firearm and ammunition cal. 7.65 mm which generally corroborates with similarly studied GSR distributions obtained for the use of pistols cal. 9 mm. This information, together with the examinations of gunshot damages and other types of residues such as soot or unburned propellant grains may support qualitative inferences on shooting distance estimation, especially in cases, when the firearm and cartridges are not available to perform test shooting. In such cases even roughly estimated shooting distance can be helpful, e.g. for confirming or excluding the possibility of self-inflicted injuries or suicide and infer on the mutual position of the shooting stage actors. An example of casework that illustrates intermediate shooting distance estimation is presented.     

生态文明视域下的桂林低碳城市建设

低碳城市建设对于推进桂林生态文明,打造国际旅游胜地具有重要意义。桂林需探索一条以低碳产业为主导的经济发展模式、市民崇尚低碳化生活方式、政府以建设低碳社会为目标、具有自身特色的低碳城市建设道路,推动经济、社会、文化、生态的可持续发展,从而实现桂林建设"全国生态文明建设示范区"的目标。     

血痕预试验检测的应用现状与研究进展

血迹是凶杀、伤害等案件中最常见和最重要的一种物证。血痕预试验是利用化学检测的方法从现场大量可疑的斑迹中初步筛选出可能是血的痕迹物证。本文对常用血痕预试验试剂的应用现状及其灵敏度、特异性、稳定性等进行分析比较,同时对预试验检测中存在的问题及今后的发展趋势进行综述,旨在为更好地研究、利用血痕预试验试剂提供参考。