Gunshot Residues

The confiscation of improvised firearms among armed robbers and antisocial participants in a range of illegal activities has surged drastically. They prefer to get improvised weaponry in a clandestine way due to their ease of availability and low cost. Each improvised firearm has a distinct effect on the target due to the lack of suitable standards and comprehension. When the shooting range must be estimated, GSR facilitates the disposition of cases in forensic ballistics. Since improvised handguns are used in the majority of reported occurrences, the range determination and its ramifications should be explored. The goal of this study was to use tattooing as a criterion to measure the range of fire with 7.65mm improvised guns. The results demonstrated that the firing range is related directly to the tattooing dispersion and simultaneously inversely proportional to the intensity of tattooing created. Tattooing dimensions were inconsistent throughout the trials with the same gun within the same range, like 5×4 cm and 13×12.5 cm. For each of the three distinct ranges (10, 20, and 30 cm), the dimensional values were repeated in between 10×11cm and 12×12cm. As a result, determining a precise range of firing of homemade weaponry by measuring the dimension of tattooing generated was practically impossible. More research on improvised weaponry should be done so that this issue may be addressed.

Earlier work has produced formulas for predicting stability of rifle bullets of near uniform density and also for plastic-tipped rifle bullets. These formulas have been shown to be accurate within 5%. However, the original Miller stability formula for metal bullets of near uniform density underestimates the stability of match style open tipped rifle bullets having a significant empty volume in the tip. This paper presents a new formula for accurately estimating the stability of these open tipped match style rifle bullets from parameters easily obtained such as the bullet mass, length, and depth of the empty space in the tip. The formula is tested by observations of whether bullets tumble and by measuring the aerodynamic drag vs. predicted stability of several bullets over a range of stabilities. In addition to confirmation in several test cases with original firing data, the new stability formula is validated by comparison with BRL spark range stability data for the 168 grain Sierra...

This paper describes the effects on aerodynamic drag of rifle bullets as the gyroscopic stability is lowered from 1.3 to 1.0. It is well known that a bullet can tumble for stability less than 1.0. The Sierra Loading Manuals (4 th and 5 th Editions) have previously reported that ballistic coefficient decreases significantly as gyroscopic stability, Sg, is lowered below 1.3. These observations are further confirmed by the experiments reported here. Measured ballistic coefficients were compared with gyroscopic stabilities computed using the Miller Twist Rule for nearly solid metal bullets with uniform density and computed using the Courtney-Miller formula for plastic-tipped bullets. The experiments reported here also demonstrate a decrease in aerodynamic drag near Sg = 1.23 ± 0.02. It is hypothesized that this decrease in drag over a narrow band of Sg values is due to a rapid damping of coning motions (precession and nutation). Observation of this drag decrease at a consistent value of...

Complete understanding of any natural phenomenon can only be achieved by explicitly expressing it in terms of primitive variables. The laws of thermodynamics have been extensively studied for centuries, accelerating societal progress through developments across several branches of science and technology. Phase nucleation can be observed in the melting and freezing of rocks and ice caps, abundant shapes of snow flocks, rain regimes, snowfall, casting, and metal forming, among other applications. The most challenging aspect of nucleation is the equilibrium shift controlled by the gradients in temperatures, species, work, and other variables, in accordance with the first law of thermodynamics, which defines the thermal field. In this study, the thermal field and thermal field tensor were defined in terms of equilibrium dislocations to assess their primitive variables. Theoretical simulations for the Gibbs-Thomson coefficients were applied to predict the experimental microstructure evolution.

La "Fourier Thermal Analysis" (FTA) è una tecnica avanzata di analisi termica, sviluppata negli anni '80-'90 per determinare il calore latente rilasciato in fase di solidificazione, allo scopo di indagare sulle cinetiche di nucleazione ed accrescimento delle varie fasi coinvolte. I risultati delle indagini condotte con questa metodologia hanno contributo allo sviluppo dei codici di calcolo per la modellazione dei fenomeni di solidificazione di leghe da fonderia come le ghise e le leghe Al-Si. Scopo di questo lavoro è la verifica delle potenzialità della FTA nello studio della modifica eutettica di una lega Al-Si, e più in generale nella dinamica della solidificazione delle leghe Al-Si. La modifica eutettica viene impiegata allo scopo di incrementare le caratteristiche di resilienza e resistenza a fatica delle leghe Al-Si, l'efficacia del trattamento è vincolata alla presenza di una percentuale minima di elemento modificante. L'analisi termica può essere impiegata per verificare il livello di modifica della lega, e quindi l'efficacia del trattamento. È stata presa in considerazione una lega della classe A356, modificata con Na metallico, e sono state confrontate le curve f s (t) e f s (T) ottenute con diversi livelli di modifica, allo scopo di correlare le caratteristiche delle curve di frazione di fase solida rispetto al tempo ed alla temperatura con le caratteristiche microstrutturali della lega.

Introduction: The aim of the study was determining the type of weapon and shooting distance depending on chemical analysis of inorganic gunshot residue from the skin gunshot wounds in experimental animals (pigs).Methods: Experimental study was conducted in order to determine components and their percentage in gunshot residue (GSR). In 60 samples, pig skin was shot by fi ring projectiles from four different weapons and from three different distances (contact wound and near contact wound from 5 cm and 10 cm). The methodology included determining the presence of inorganic material: antimony, barium, lead, nickel, zinc and copper in the skin and subcutaneous tissue using atomic absorption spectrophotometry (AAS).Results: Formula for determining weapon type was provided cutt-off points for different weapons, with 78.6% of original grouped cases being correctly classifi ed. Formula for determining weapon type was provided cutt-off points for different distances, with 58.9% of original gro...

Firearms are widely used, and their modeling has become a research topic in the field of internal ballistics. This study aims to create a thermodynamic and mechanical incorporation model of a 19-9 mm Parabellum round shot in a Glock 19 firearm to examine the internal conditions of the firearm when the bullet is fired. Simulations show that the bullet exits the barrel at 391.74 µs with a speed of 357.16 m/s. The simulation also shows force and pressure graphs similar to other models.

A espectroscopia de emissão em plasma induzido por laser (LIBS) foi avaliada para a detecção de resíduos de disparo de arma de fogo (GSR) nas mãos de um suspeito. Para desenvolver o procedimento, 114 amostras foram obtidas pressionando um pequeno pedaço de fita adesiva contra a região dorsal das mãos de não-atiradores, atiradores após o disparo e de atiradores após terem lavado as mãos com sabão e água. As fitas foram analisadas diretamente em um equipamento LIBS baseado em um policromador echelle com resolução temporal construído em laboratório. Os espectros foram obtidos a partir da aplicação de um único pulso de laser em 20 locações diferentes, espalhadas uniformemente sobre a superfície da fita, para assegurar uma amostragem eficiente na detecção de resíduos de disparo. Os espectros mostram uma assinatura com linhas de emissão características de bário e chumbo. Quando os dados espectrais foram submetidos à técnica de reconhecimento de padrão SIMCA (Modelagem Independente e Flexível por Analogia de Classe), atiradores e não-atiradores foram corretamente classificados. O método baseado em LIBS e SIMCA demonstrou ser não-destrutivo da evidência do crime e permitiu discriminar as amostras coletadas de voluntários não-atiradores e atiradores, mesmo após a lavagem das mãos. Laser induced breakdown spectroscopy (LIBS) is further developed for the detection of gunshot residue (GSR) on the hands of a suspected shooter. To develop the procedure, 114 samples were obtained by pressing a small piece of adhesive tape against the dorsal region of the hands of nonshooters, of shooters just after firing a weapon, and of shooters after washing their hands with soap and water. The tapes were analyzed directly in a time-resolved echelle based LIBS system, assembled in the laboratory, and 20 single laser pulses, spread uniformly on the tape surface, were shown to be enough to ensure the detection of true positives. The spectra obtained by LIBS from the tape present a signature with emission lines that are attributed to barium and lead. After the spectral data was submitted to a pattern recognition method SIMCA (Soft Independent Modeling of Class Analogy), shooters and non-shooters were corrected classified. The method based on LIBS and SIMCA has been demonstrated to be non-destructive of crime evidence and enabled discrimination between the samples collected from non-shooter volunteers and shooter volunteers before and after washing their hands.

The presence of tin in gunshot residue (GSR) particles from ammunitions used in short and long rifled firearms is well known and widely documented. Tin does not originate from the primer mixture itself but is typically linked to a thin disc-shaped foil placed over mercury fulminate-based primers to prevent embrittlement of the cartridge case and primer cap. However, this practice has not been previously reported or observed in hunting ammunitions. We designed an experimental protocol to investigate the formation of quaternary GSR particles containing Pb-Ba-Sb-Sn, following shots fired from a double-barrel shotgun using modified hunting ammunitions. These ammunitions were loaded with multiple pellets and included a thin tin foil over the primer's flash hole. Our results confirm that the tin foil is directly responsible for the origin and composition of the quaternary GSR particles detected on the collected stubs. Additionally, the hunting ammunitions market has recently seen increased production of environmentally friendly ammunitions, including shot pellets made of tin, tin alloys, or coated with tin. Our findings provide a foundation for further experimental studies into GSR from such eco-friendly ammunitions, especially in forensic investigations involving tin-containing pellets.

A comprehensive series of tests were performed to determine how the gunshot angle of incidence will affect the amount and density of gunshot residue (GSR) upon a target. Test shots were performed at four different angles (0, 30, 45, and 60 degrees). Two handgun calibers (9mm & .45ACP) were included. Testing was at two distances (9"/23cm and 15"/38cm). All targets were photographed. The amount and density of the GSR was quantified using image analysis software and subjected to statistical analysis. The testing demonstrated that as the shooting angle increases from the orthogonal position, the amount and density of GSR on the target is diminished.

Environmental monitoring in cleanrooms requires an assessment of the population of microorganisms on a surface. Often the surfaces within cleanrooms contain residues of cleaning and disinfection agent. These agents can suppress the growth of microorganisms when surface samples are taken (using the contact plate). This tendency towards ‘false negatives’ can be overcome by including a neutraliser in the agar formulation. This article describes the role of neutralisers and a test method to assess neutraliser suitability in overcoming disinfectant residues.

Sandle, T. (2025) Avoiding false negatives: Assessing the suitability of critical surface contact plate neutralisers, Clean Air and Containment Review, 53 (4): 24-27

Forensic applications of Scanning Electron Microscopy (SEM) are found mostly in areas where there is a need for good imaging at relatively high magnifications. SEM enables the forensic scientist to examine specimens at much higher magnification than those possible with optical microscopy and without the difficulties of specimen preparation associated with conventional electron microscope. Physicochemical examinations of gunshot residues, called also chemical ballistics, are helpful, e.g. in identification of damages and injuries as the effect of the use of firearms (with indicating the entrance and exit of projectile), estimation of the shooting distance and also establishing, whether a person has used a firearm. It is discussed in details that Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM-EDX) can serve as a powerful tool for forensic scientists to classify and discriminate evidence material because they can simultaneously examine the morphology and the elemental composition of objects.

This module presents a real-world context in which mathematics skills are used as part of a daily routine. The context is the industrial and engineering technology area, and the module aims to help students see the significance of mathematics skills in performing daily tasks. Materials in the module, most of which are designed for the teacher to duplicate and distribute to students, include the following: (1) information on careers in engineering technology; (2) a task to be performed and information sheets necessary to complete the task; (3) questions to be completed by the students; (4) answer keys to the questions; and (5) a handout and teacher's answer key. (KC)

This live-fire experiment was conducted to determine if we could replicate spherical ball-damaged objects surviving from April 19, 1775, the first day of the American Revolution. The standing structures damaged by gun fire on April 19 now exist amidst a modern built and modified landscape. However, those buildings and places still remain and anchor us to that past by their very existence. These places, Elisha Jones’ shed, Munroe Tavern, Buckman Tavern, Marrett Munroe house, Jason Russell house, and other preserved artifacts have become “hallowed” because they either still stand or exist in collections.

Aflatoxin B1 is a mycotoxin that can contaminate a wide feedstuffs variety. Ingestion of contaminated feed by poultry can lead to impaired health and zootechnical performances but also a human diet safety problem related to residues presence in animal origin products. Aflatoxin B1 contamination of poultry feed samples marketed in Dakar city and in peri-urban areas (Gorom, Sangalkam) was studied. A total of 15 samples were collected from Dakar city markets as well as from poultry farms in Gorom and Sangalkam areas. Aflatoxin B1 quantification was performed by high performance liquid chromatography and thin-layer chromatography. HPLC results showed that all samples were contaminated with levels ranging from 0.15 to 22 ppb, 0.099 to 2.05 ppb and 0.099 to 4.95 ppb respectively for Gorom, Sangalkam and Dakar. Only the finishing feed from Gorom had an aflatoxin B1 level above the maximum limit set by regulations. TLC is a suitable method for aflatoxins detection. However, it was associated with overestimation for aflatoxin B1 quantification. Results suggest that poultry feed represents a real source of human diet contamination. In addition, HPLC remains the most reliable quantification technique for quality control.

In forensic ballistics, gunshot residue (GSR) particles can be detected using screening or presumptive tests which are mainly focused on the chromophoric reaction. Most tests serve as an initial indication for a forensic investigator at the crime scene before instrumental analysis for definitive identification. The screening methods are known to be convenient, have fast analysis, and minimal preparation. In GSR analysis, the wellknown method of detecting GSR known as the Modified Griess Test (MGT) requires acid and heat for the reaction. Therefore, this study demonstrated a new and rapid screening test named the Rapid Griess Test (RGT) for the detection of GSR. This study intends to improve the functionality of previous screening reagents in determining nitrite (NO 2-), the composition present after shooting activity. To do this, chemical reagents with an amino group, 3-aminophenol, were substituted with alpha-naphthol. The experiment showed that the reactions were positive color changes using standard NO 2and real GSR samples. The diazotization reactions involving sulfanilic acid and 3-aminophenol produced azo dyes that changed the solution from colorless to orange in the presence of NO 2-. The RGT reagent will make it possible to avoid using heat and the addition of acetic acids in a sample to form chromophoric reactions. Moreover, the colorimetric method using Video Spectral Comparator (VSC) showed that RGT had higher intensity of the orange color when compared to MGT.

In forensic ballistics, gunshot residue (GSR) particles can be detected using screening or presumptive tests which are mainly focused on the chromophoric reaction. Most tests serve as an initial indication for a forensic investigator at the crime scene before instrumental analysis for definitive identification. The screening methods are known to be convenient, have fast analysis, and minimal preparation. In GSR analysis, the well-known method of detecting GSR known as the Modified Griess Test (MGT) requires acid and heat for the reaction. Therefore, this study demonstrated a new and rapid screening test named the Rapid Griess Test (RGT) for the detection of GSR. This study intends to improve the functionality of previous screening reagents in determining nitrite (NO2–), the composition present after shooting activity. To do this, chemical reagents with an amino group, 3-aminophenol, were substituted with alpha-naphthol. The experiment showed that the reactions were positive color ch...

Clothing damage analysis is an important tool for forensic investigations and, even it is a niche field, it is gaining interest. Moreover, the attention is shifting from evaluating just the "biological" traces found on the clothes to the modifications that clothes themselves undergo in the context of a specific traumatic dynamic. The Authors analyze a case of the investigation on a hole in the jacket worn by the victim when he was attacked, performed through optical microscope and morphological and elemental SEM/EDX analysis, to determine the origin of this texture damage to verify a witness story.

Forensic Chemistry Available online 9 January 2023, 100472 In Press, Journal Pre-proofWhat are Journal Pre-proof articles? On the problem of data interpretation in the analysis of iron-containing GSR particles Author links open overlay panelMarcoRomeoaFeliceNunziatae https://doi.org/10.1016/j.forc.2023.100472 Get rights and content Highlights • Iron is an element that can be present within a GSR particle; • The iron present in a GSR particle can be derived from several sources; • Forensic experts hypothesize that the iron may have come from the barrel of the firearm; • Several iron particles from the barrel of the firearm and other sources were analyzed; • In gunfire with rusty barrels, iron particles aggregate with GSRs in the cooling phase. Abstract Many forensic experts hypothesize that iron found in gunshot residues (GSRs) derive from melted iron particles because the steel of the barrel consists mainly of iron. This is a strong hypothesis that deserve careful investigation. To this purpose, we focused our attention on erosion and corrosion mechanism occurring in the barrel that can influence GSRs. A preliminary physicochemical interpretation consistent with the analytical results was presented. Moreover, spectra and images of GSRs originated from the firing of ammunition by firearms having rusty barrels and of iron oxide particles not originated from the firing were analyzed. The obtained results are discussed, taking into account the chemical content and morphology of the observed particles taking in account the context both of the erosion and of the corrosion and of the GSRs formation process

In order to have confidence in the integrity of a GSR test result, it is essential to understand the factors that may influence the presence of GSR particles on a person of interest's hands beyond the discharge of a firearm. One important consideration is the possibility that a person of interest (POI) may become contaminated with GSR through their interactions with firearms-carrying police officers during the process of apprehension or arrest. This situation has the potential to result in a false positive error, and potentially result in the mistaken inclusion of a POI in an investigation. Prior studies have indicated that receiving a firearm at the start of shift represents a significant contamination event, which may result in GSR persisting on the hands of police officers (Cook, 2016). Firearms-carrying police officers were sampled at various points throughout their shift to ascertain the extent of persistence of GSR on their hands, as a potential population that could then be transferred. A secondary transfer study was also conducted, with several 'mock arrest' scenarios used as a means of modelling the extent and dynamics of any secondary GSR transfer. When compared to the random population, it was found that police exhibit GSR contamination of their hands at a higher frequency. 7.9% of the officers sampled in this study returned at least one, 3-component particle characteristic of GSR. Further, 75% of the officers tested had at least one particle considered consistent with GSR present on their hands. However, the overall particle numbers were relatively low, with the average reported number of characteristic particles being less than five, and the greatest number reported being twelve. When considering the possibility of secondary transfer occurring during the process of arrest, it was further determined through secondary transfer experiments that the most probable transfer situation was fewer than 25% of the particles present on an officer's hands would be transferred to a POI as a result of a short 'mock arrest' contact. We conclude that although the possibility of GSR contamination through the process of arrest exists, and is worthy of consideration in the assessment of GSR evidence, it is not an overwhelming, or major concern.

Aflatoxin B1 (AFB1) belongs to a group of hepatocarcinogenic and hepatotoxic mycotoxin produced by Aspergillus flavus and Aspergillus parasiticus found in food or feed products. In this study we analyzed 180 feed of six different brands of commercial poultry feeds from three feed distribution outlets in Ibadan, southwest Nigeria for the occurrence and concentrations of AFB1. In addition, to the transfer of AFB1 to broiler meat from chicken fed for four weeks with one brand of feed associated with the highest AFB1 contamination. The study was carried out between April and June, 2019. The presence/concentration of AFB1 was determined using High Performance Liquid Chromatography (HPLC) following solid phase extraction of sample and preparation. Aflatoxin B1 was detected in all (100 %) the brands of feed and 48 % of chicken samples tested. The concentration of AFB1 in feed ranged between 10.5 ± 4.0 and 47.78 ± 6.4, while the mean AFB1 residues obtained in chicken muscle, gizzards and li...

Rapid advances in 3D-printing technology have created an emerging class of firearms. As the movement to self-manufacture firearms with 3D-printing grows, it is reasonable to assume that they will be increasingly used in crimes. Here, we test-fired gun barrels made with acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), polyethylene terephthalate (PETG), chlorinated polyethylene (CPE), and nylon. The resulting cartridge cases, bullets, and gunshot residue (GSR) were examined by direct analysis in real time-mass spectrometry (DART-MS). High-resolution mass spectra detected polymer from the gun barrel on bullets and cartridge casings for a 0.38 special caliber gun and, to a lesser extent, for a 0.22 caliber 3D-printed gun. Particles of plastic were identified in some GSR samples collected from clothing used as a backstop for test-fires. DART-MS also readily detected signature organic GSR compounds, including methyl centralite, ethyl centralite, diphenylamine, and nitrocellulose, on recovered bullets, cartridge cases, and in extracts of SEM stubs used to collect GSR from the clothing. Overall, this study demonstrates that analysis of firearm trace evidence using DART-MS deserves more attention, and that the technique may be particularly useful for investigating crimes involving 3D-printed guns.

Gunshot residue (GSR) stemming from the discharge of firearms has been essential to advancements in the field of forensic science however the human and environmental health impacts from GSR are far less researched. GSR represents a multifaceted concern: it contains a complex mixture of inorganic and organic components and produces airborne particles with variable sizes, depositions, and fates. Herein we evaluate studies in the literature examining GSR collection, deposition, composition, environmental contamination, and potential remediation techniques within the last two decades (2000-2020). Throughout we reflect upon key findings and weaknesses in relation to environmental characterization of GSR and associated firearm contaminants. Research focused on techniques to analyze both inorganic and organic GSR simultaneously has begun, but requires additional effort. A vast majority of the available environmental characterization literature focuses on soil contamination at outdoor firing ranges for a select number of elements (Cu, Pb, Sb) with comparisons between ranges or at different collection distances and depths. There is limited ability for between study comparisons due to collection and analysis differences as well as a lack of background soil sampling. Notably, these studies lack direct quantification of the contribution of contaminants from GSR as well as analysis of organic compounds. Currently, there is a need for air monitoring to determine the composition, deposition, and fate of GSR, particularly in outdoor settings. This review summarizes the collection, characterization, and environmental studies related to GSR and highlights areas of research needed to establish the environmental health impacts.

Modelling of shock waves crossing material with several phase transitions requires the knowledge of the equation of state (E.o.S.) of the material and its thermodynamic properties. The phase transitions correspond to volume and entropy jumps and discontinuities of extensive properties of the different phases. Building a complete E.o.S. with numerous crystallographic phase transitions raises many issues. It is generally a function of volume and temperature although thermodynamic equilibrium is defined for given temperature and pressure. Experimental data are generally available only in the (P,T) plane. Only few experimental data exist about the volume jump and none for the entropy jump. We propose an algorithm to build complete E.o.S. including several solid/solid or solid/liquid phase transitions. Each phase has its own E.o.S. and independent parameters. The phase diagram is calculated from the Gibbs free energy minimum. The phase transition is calculated from the Gibbs free energy equality between two phases which provides the thermodynamic properties of their binary mixture, and volume and entropy jumps. We explain how to determine these jumps in accordance to thermodynamic rules and experimental data. Until now, such an approach was used in simple cases and limited to 2 or 3 phases. We have applied it in the general case to bismuth for which up to 11 phases have been identified. This study show the great influence of binary mixtures and triple points properties in released isentropes after shock waves.

This study investigated the use of laser-induced breakdown spectroscopy (LIBS) and scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDX) as means of characterizing gunshot residue (GSR) originating from commercially available lead-free rounds. Data from two experiments are presented in this work. One experiment focused on identifying prominent analytical markers present in lead-free GSR by LIBS while the other applied SEM-EDX to determine the degree of evidence preservation after LIBS analysis. Samples of GSR were collected via tape-lift method from the hands of volunteer shooters and instrumental analyses were conducted in triplicate. As a result, the lead-free ammunition analyzed in this work generated GSRs comprising primarily Ba, Al, Si, and/or K. Trace amounts of Ti, Fe, and S were also apparent in some compositions. Through SEM-EDX analysis, a spheroidal geometry consistent with traditional lead-containing GSR was observed. Additionally, it was determined that evidence is preserved after LIBS analysis which supports the implementation of LIBS as a rapid preliminary screening method followed by confirmatory testing via SEM-EDX on the preserved evidence.

Shooting distance estimation offers useful information for the reconstruction of firearm related incidents. The muzzle to target distance is usually estimated by examining the bullet entrance hole and the gunshot residue pattern. To visualize the pattern the forensic analyst usually uses presumptive tests based on color chemical reactions that are applied using long and tedious proceedings. Due to the drawbacks of the chemical tests recent developments for shooting distance estimation not based on color chemical tests were described in the literature. The present review covers the approaches for shooting distance estimation published in the last 10 years considering two types of target, clothing and skin.

Please cite this article as: Zuzanna Brożek-Mucha , A study of gunshot residue distribution for close-range shots with a silenced gun using optical and scanning electron microscopy, X-ray microanalysis and infrared spectroscopy. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Scijus(2016),

Hajossy et al (1999 J. Phys. D: Appl. Phys. 32 1058) alleged that the break of a short circuit is preceded by the ignition of an arc because they estimated the relative field strength to be high enough for this to occur. This assertion has proven inconsistent with measured data. In particular, the typical sudden change from progressively rising to sharply dropping voltage contrasts with the alleged gradual commutation, but rather points to a detonation across the isthmus. Concerning the confinement of metal vapour due to inertia, the comment refers to Hess (1991 J. Phys. D: Appl. Phys. 24 36-40). There are several substantiated reasons why the minimal diameter of the bridge and also the voltage, required for a bypassing ignition, are actually larger than the values estimated by Hajossy et al, and why the bridge does not simply vanish. Somewhat misleading observations are blamed for the fallacies. The established wire explosion model of re-ignition is certainly valid, even in general. For that reason, there is no hope that the alleged premature ignition could be used for avoidance of the spatter-causing explosion.

In case of gunshot wounds, forensic anthropologists and pathologists have many tools at hand, and the assistance that chemical and microscopic investigations can provide in such scenarios is often valuable and crucial. However, the results of such analyses in the search of gunshot residues (GSR) ought not to be acritically considered. We report five cases where chemical (sodium rhodizonate) and microscopic (scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX)) analyses were performed for the search of GSR. Four cases concerned the forensic field and analyses on buried, charred, or submerged remains, whereas one case concerned the historical remains of a soldier of the First World War. In every case, the search for GSR with these techniques showed their persistence even after long periods and preservation in peculiar environments. However, chemical analyses provided their contribution, but in two cases, anthropological analyses provided crucial and solving results. The five cases show the indisputable usefulness of chemical and microscopic analyses in the search of GSR in gunshot wounds and especially how such residues may survive in time and in adverse environmental conditions. However, experts should always be dubious about some pitfalls (such as contamination) one can frequently find in these scenarios.

In case of gunshot wounds, forensic anthropologists and pathologists have many tools at hand, and the assistance that chemical and microscopic investigations can provide in such scenarios is often valuable and crucial. However, the results of such analyses in the search of gunshot residues (GSR) ought not to be acritically considered. We report five cases where chemical (sodium rhodizonate) and microscopic (scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX)) analyses were performed for the search of GSR. Four cases concerned the forensic field and analyses on buried, charred, or submerged remains, whereas one case concerned the historical remains of a soldier of the First World War. In every case, the search for GSR with these techniques showed their persistence even after long periods and preservation in peculiar environments. However, chemical analyses provided their contribution, but in two cases, anthropological analyses provided crucial and solving results. The five cases show the indisputable usefulness of chemical and microscopic analyses in the search of GSR in gunshot wounds and especially how such residues may survive in time and in adverse environmental conditions. However, experts should always be dubious about some pitfalls (such as contamination) one can frequently find in these scenarios.

Due to concerns about environmental and industrial hazards of lead, a number of military, law enforcement, and wildlife management agencies are giving careful consideration to lead-free ammunition. The goal of lead-free bullets is to gain the advantages of reduced lead use in the environment while maintaining equal or better terminal performance. Accepting reduced terminal performance would foolishly risk the lives of military and law enforcement personnel. This paper uses the established technique of studying bullet impacts in ballistic gelatin to characterize the terminal performance of eight commercial off-theshelf lead-free handgun bullets for comparison with earlier analysis of jacketed lead bullets. Peak retarding force and energy deposit in calibrated ballistic gelatin are quantified using high speed video. The temporary stretch cavities and permanent wound cavities are also characterized. Two factors tend to reduce the terminal performance of these lead-free projectiles compared to similar jacketed lead designs. First, solid copper construction increase barrel friction, which reduces muzzle velocity and energy, and thus reduces the ability of the bullet to exert damaging forces in tissue simulant. Second, the lower density of copper requires a longer bullet for a given mass and caliber, which reduces remaining powder volume in the brass cartridge case, which also tends to reduce muzzle velocity and energy. The results of the present study are consistent with earlier analysis showing that expansion is necessary to maximize the potential for rapid incapacitation of enemy combatants. In spite of some new non-expanding nose designs that moderately increase forces between bullet and tissue, the largest retarding forces and highest incapacitation potential requires expanding bullets which maximize frontal area.

This study relies on the ability of six different fabrics to retain gunshot residues on their surfaces, and their capability to let them pass through. The fabrics were cotton, linen, elastane, polyester, silk and viscose, each of them placed above a filter paper sheet. This last was used to retain residues passing through fabric. Microscopic structures of the chosen textiles were characterized by optical microscopy, and their surface morphology was characterized by stylus profilometry. A semi-automatic Sig Sauer P228 pistol, calibre 9 × 21 mm IMI, was exploited and two shooting distances were considered, 10 cm and 40 cm. Preliminary, inorganic residue (IGSR) deposition patterns were visualized by X-ray fluorescence spectroscopy. Scanning electron microscopy was also used to describe morphology and composition of IGSR generated by discharging the selected gun. Concentration of IGSR on targets was then quantitatively determined by inductively coupled plasma optical emission spectrometry, while nitrites and nitrates, originated by nitrocellulose content of smokeless powders, were identified by ion chromatography. As expected, the amount of metallic residues, nitrites and nitrates decreases inversely with the shooting distance. In addition, considering the same distance, concentration of these elements changes significantly depending on the analyzed cloth. Therefore, when evaluating shooting distance in a forensic case, the habit to use a cotton textile to construct a calibration curve, despite of the actual nature of the target, could not be quantitatively accurate. It was evidenced that a significant amount of GSR passed through target fabrics, making their identification possible even on underneath tissues.

The aim of this work was to characterise three non-toxic ammunition (NTA) from the GECO and Fiocchi brands, which are available in the Italian market. Characterisation was carried out by considering both the elemental chemical composition and morphology, using scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDS). Particles were collected from both the cartridge cases and the shooters' hands after shooting tests. Six volunteers fired two shots for each ammunition. Several elements, such as aluminium, potassium, silicon, sulphur, titanium and zinc were found in gunshot residue (GSR) particles from different ammunition. We also studied the persistence of these types of GSR on the hands of the shooters in a range between 1 and 6 h after shooting. The GSR particles from the three NTA tested were found on the hands of shooters until 6 h after the shots. The characterisations undertaken in this work will be useful for specialists in forensic science and legal medicine to evaluate trace evidence from these new NTA in casework, as such formulations are in growth.

Milk and milk products are the most important group of food which carries aflatoxin to the people. Therefore, the existence of aflatoxin M 1 (AFM 1) in milk is a potential risk for public health. AFM 1 existence in milk and milk products was found in studies performed in Turkey. In this study, aflatoxin contamination was detected in 48 raw milk and 48 feed samples. Milk and feed samples, in which the positive sample rate was determined as 24%, included different levels of aflatoxin. Altogether, 20 raw milk samples (41.67%) and 15 feed samples (31.25%) contained over the level of legal limits established by the Turkish Food Codex (TFC) and the European Communities (EC) regulation in positive samples. According to these results, the milk and feed samples collected from this area constitute a potential risk for public health. The most effective way of controlling aflatoxin M 1 in milk is to reduce the contamination of aflatoxin in raw milk and feed samples. Both the producers and the consumers, as well as the government, have important obligations on this subject.

• A new cartridge 9 × 19 mm pollution reduced for law-enforcement use is presented. • Primer gunshot residues are tagged by the presence of Sm and Ti in p-GSR. • DTO test is used to visualize muzzle projection patterns, due to metallic copper in powder.

A gunshot residue sample that was collected from an object or a suspected person is automatically searched for gunshot residue relevant particles. Particle data (such as size, morphology, position on the sample for manual relocation, etc.) as well as the corresponding X-ray spectra and images are stored. According to these data, particles are classified by the analysis-software into different groups: 'gunshot residue characteristic', 'consistent with gunshot residue' and environmental particles, respectively. Potential gunshot residue particles are manually checked andif necessaryconfirmed by the operating forensic scientist. As there are continuing developments on the ammunition market worldwide, it becomes more and more difficult to assign a detected particle to a particular ammunition brand. As well, the differentiation towards environmental particles similar to gunshot residue is getting more complex. To keep external conditions unchanged, gunshot residue particles were collected using a specially designed shooting device for the test shots revealing defined shooting distances between the weapon's muzzle and the target. The data obtained as X-ray spectra of a number of particles (3000 per ammunition brand) were reduced by Fast Fourier Transformation and subjected to a chemometric evaluation by means of regularized discriminant analysis. In addition to the scanning electron microscopy in combination with energy dispersive X-ray microanalysis results, isotope ratio measurements based on inductively coupled plasma analysis with mass-spectrometric detection were carried out to provide a supplementary feature for an even lower risk of misclassification.

Gunshot residues (GSR) are of interest when firearms are used in criminal cases. GSR analyses are usually based upon the elemental composition and morphological appearance of very minute particles by means of SEM-EDS. Based on these two parameters, GSR particles are divided into specified classes. The amount of detected GSR particles depends on the time since discharge of the weapon and the sampling position relative to the location of discharge. In this paper, the influence of time on the local concentration and the distribution of airborne GSR particles were investigated with impactor technology. The particle concentration is constant in the still room; changes in concentration are only related to the emission of GSR particles by the discharge of a firearm. Here we showed that large quantities (50% of max. concentration) of airborne GSR particles can be detected several hours after discharge and contamination can take place as much as three hours after discharge. This study is a first approach to describe the propagation and sedimentation of GSR particles. With respect to statistical confirmation further experiments are already projected in order to comprehend the well-known variability of GSR emission and behavior.

Law enforcement agencies routinely sample for gunshot residue (GSR) by bulk techniques and often submit swabs taken from other surfaces besides the hands of the suspect shooter. This study aims to establish the prevalence of antimony, barium, and lead on normally handled automobile surfaces by graphite furnace atomic absorption analysis. No positives were determined on 50 sampled automobile surfaces above cutoff (positive) from background levels. Transfers of GSR particles from shooter hands to automobile surfaces were found to potentially allow for positive GSR determinations, but such transfers seem to be dependent on the shooting conditions and length of GSR exposure. We determined that our bulk analysis method yields an overall 87.94 AE 5.52% extraction efficiency from cotton swabs, while the LOQ determinations strengthening the fact that bulk analysis methods are valid and valuable tools for GSR investigations.

del gas di elettroni liberi. Teoria quantistica del gellio. Stato fondamentale del gellio nell'approssimazione di Hartree-Fock. Scambio. Approssimazione locale di Slater. Correlazione elettronica. Buca di Fermi. Gas elettronico polarizzato. Cristallo di Wigner. Schermo. Funzione dielettrica. Modelli di Thomas-Fermi e di Lindhard. Schermo dinamico. Plasmoni nei metalli. Funzione dielettrica longitudinale e trasversale. Proprietà ottiche dei semiconduttori. Proprietà di trasporto. Dinamica semiclassica degli elettroni. Equazione di Boltzmann. Approssimazione del tempo di rilassamento. Conducibilità statica e dinamica dei metalli. Dinamica in campo magnetico. Effetto Hall e magnetoresistenza. Gas bidimensionale di elettroni. Livelli di Landau. Effetto Hall quantistico intero. Risposta magnetica del gas di elettroni liberi. Paramagnetismo di Pauli. Diamagnetismo di Landau. Superconduttività. Coppie di Cooper. Teoria BCS. Fenomenologia e applicazioni della superconduttività.

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Töö eesmärgiks oli kuuli sisenemisavade võrdlemisel välja selgitada riide- ja nahavigastuste/sadestuste suhe laskekaugusega ning näidata, et relvaraua õõne ehitus mõjutab tahmasadestuse mustrit. Eksperimentaallasud sooritati püstolitest Tokarev, Makarov ja Glock 19 standardse laskemoonaga 1 cm kuni 100 cm kauguselt. Võrreldi puuvillasele ja polüesterriidele ning nahale (lahangumaterjal) tekitatud vigastusi/sadestusi. Järeldused: 1. Tulemused riietel ja nahal olid sarnased. 2. Erinevused leius olid tingitud laskekaugusest ja relvast. 3. Statistiliselt oluline seos oli laskekauguse ja riietel oleva tahmasadestuse läbimõõdu vahel, samuti laskekauguse ja püssirohuosakeste arvu vahel. Negatiivses seoses oli püssirohuosakeste arv ja nende paiknemiskoha kaugus riidedefekti keskkohast. Uurides laskekauguse ja püssirohu nahakihtides leidumise vahelist seost, ilmnes et püssirohuosakesed võivad tungida epidermisesse ja dermasse või j...

The most popular handgun in Brazil is the single round-barrel caliber 0.38 revolver. In recent years, however, owing to the modernization of police arms and their availability on the legal and illicit markets, pistols have become increasingly popular and currently represent about 20% of police seizures. In a previous paper we presented a novel collection method for gunshot residues (GSR) using a sampling procedure based on ethylenediamine-tetraacetic acid (EDTA) solution as a complexing agent on moistened swabs with subsequent detection using sector field-high resolution-inductively coupled plasma-mass spectrometry (SF-HR-ICP-MS). In the present paper, we discuss the capability of this methodology to identify antimony (Sb), barium (Ba) and lead (Pb) on the hands of volunteers after shot tests with 9 mm and 0.40 in. caliber pistols. Two types of munitions were tested: 9 mm Taurus and clean range. The use of a technique with high sensitivity, such as SF-HR-ICP-MS, permits the identification of low concentrations (less than 1 mg/L) of metals in firearm residue and constitutes a powerful tool in forensic science. We also discuss the importance of the sampling procedure, including collection from a different body part than the gun hand of the suspect. Comparison of the analytical data obtained allows clear discrimination between samples from the hands of shooters and non-shooters.

Shooting distance estimation offers useful information for the reconstruction of firearm related incidents. The muzzle to target distance is usually estimated by examining the bullet entrance hole and the gunshot residue pattern. To visualize the pattern the forensic analyst usually uses presumptive tests based on color chemical reactions that are applied using long and tedious proceedings. Due to the drawbacks of the chemical tests recent developments for shooting distance estimation not based on color chemical tests were described in the literature. The present review covers the approaches for shooting distance estimation published in the last 10 years considering two types of target, clothing and skin.

The present study was intended to estimate the specific genetic variants by using nine genetic markers among five rabbit breeds (New Zealand White, California, Chinchilla, Flander, and Babion) in Egypt. A total of 128 animals were used (19-35 rabbits per breed). A total of 97 alleles were detected across the breeds and the average number of alleles per locus was 2.16±0.11. Five private alleles were present in Babion breed, where the locus INRACCDDV0023 had two private alleles of 293 and 297 base pairs with allele frequencies of 0.4 and 0.1, respectively. The INRACCDDV0036, INRACCDDV0304, and INRACCDDV0241 loci had private allele for each (185bp (freq: 0.24), 197 (freq: 0.47), and 137bp (freq: 0.26), respectively). The mean of H e values ranged from 0.35±0.06 to 0.49±0.07. The average of the polymorphic information content was 0.41 (ranged from 0.298 at INRACCDDV0211 to 0.599 at INRACCDDV0036 locus). To estimate the genetic deviation of the five rabbit breeds, two parameters were evaluated: genetic differentiation (F ST), and genetic distance. The F ST values varied from 0.029 (INRACCDDV0036) to 0.785 (INRACCDDV0022). The similarity matrix showed that the Chinchilla breed was distinct from other breeds. In addition, among the nine loci, the Hardy-Weinberg equilibrium was highly significant for five loci. Therefore, the rabbit breeds are good reservoirs of allelic diversity that is the major basis for genetic improvement. Consequently, the breeders need a formal conservation plan for such breeds that are in danger of extinction in near future.

A survey of the contamination of maize with aflatoxins, fumonisins and zearalenone was carried out in the Southeastern and Central Highland provinces in Vietnam. Four provinces were chosen for sampling maize: Dong Nai (22), Binh Phuoc (25), Dak Lak (30) and Dak Nong (20). Aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), G2 (AFG2), fumonisin B1 (FB1), fumonisin B2 (FB2) and zearalenone (ZEA) were analysed by HPLC in 97 maize kernel samples. Fumonisins were the most common toxins found in all samples (67%), followed by aflatoxins (55.7%) and zearalenone (27.8%). The incidence of aflatoxin positive samples (61.7%) in the Southeastern provinces was higher than in the Central Highlands (50%), while fumonisins and zearalenone incidences were higher in the Central Highlands. The mean level of fumonisin B1 in samples from the Central Highlands provinces (1757 µg/kg) was significantly greater (p < 0.05) than in the Southeastern provinces (740 µg/kg). Importantly, the percentage of positive samples (about 70%) that had over 20 µg/kg (ppb) aflatoxin was very high. Moreover, many samples (53%) contained more than one mycotoxin and this result highlights the difficulty of diagnosing mycotoxicoses in the field and the need for ongoing research to reduce the occurrence of mycotoxins in Vietnamese maize.