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Research on the expansion and fracture of explosively driven metal shells has been a key issue in weapon development and structural protection. It is important to study and predict the failure mode, fracture mechanism, and fragment distribution characteristics of explosively driven metal shells. In this study, we used the finite element-smoothed particle hydrodynamics (FE-SPH) adaptive method and the fluid-structure interaction method to perform a three-dimensional numerical simulation of the expansion and fracture of a metal cylindrical shell. Our method combined the advantages of the FEM and SPH, avoiding system mass loss, energy loss, and element distortion; in addition, the proposed method had a good simulation effect on the interaction between detonation waves and the cylindrical shell. The simulated detonation wave propagation, shell damage morphology, and fragment velocity distribution were in good agreement with theoretical and experimental results. We divided the fragments into three regions based on their shape characteristics. We analyzed the failure mode and formation process of fragments in different regions. The numerical results reproduced the phenomenon in which cracks initiated from the inner surface and extended to the outer surface of the cylindrical shell along the 45° or 135° shear direction. In addition, fragments composed of elements are identified, and the mass and characteristic lengths of typical fragments at a stable time are provided. Furthermore, the mass and size distribution characteristics of the fragments were explored, and the variation in the fitting results of the classical distribution function under different explosion pressures was examined. Finally, based on mathematical derivation, the distribution formula of fragment velocity was improved. The improved formula provided higher accuracy and could be used to analyze any metal cylindrical shells with different length-to-diameter ratios. [ABSTRACT FROM AUTHOR]

Already for some decades lateral flow assays (LFAs) are 'common use' devices in our daily life. Also, for forensic use LFAs are developed, such as for the analysis of illicit drugs and DNA, but also for the detection of explosives and body fluid identification. Despite their advantages, including ease-of-use, LFAs are not yet frequently applied at a crime scene. This review describes (academic) developments of LFAs for forensic applications, focusing on biological and chemical applications, whereby the main advantages and disadvantages of LFAs for the different forensic applications are summarized. Additionally, a critical review is provided, discussing why LFAs are not frequently applied within the forensic field and highlighting the steps that are needed to bring LFAs to the forensic market. [ABSTRACT FROM AUTHOR]

Microfluidic technology is a powerful tool to enable the rapid, accurate, and on-site analysis of forensically relevant evidence on a crime scene. This review paper provides a summary on the application of this technology in various forensic investigation fields spanning from forensic serology and human identification to discriminating and analyzing diverse classes of drugs and explosives. Each aspect is further explained by providing a short summary on general forensic workflow and investigations for body fluid identification as well as through the analysis of drugs and explosives. Microfluidic technology, including fabrication methodologies, materials, and working modules, are touched upon. Finally, the current shortcomings on the implementation of the microfluidic technology in the forensic field are discussed along with the future perspectives. [ABSTRACT FROM AUTHOR]

• Papers were evaluated and trends and gaps in the use of hyperspectral imaging (HSI) in forensic science were described. • Document examination was the most prominent area exploring HSI. • VIS and NIR-HSI were the predominant techniques for forensic evidence characterization. • Chemometric tools are crucial to extract most important information from the samples. Analysis of evidence is a challenge. Crime scene materials are complex, diverse, sometimes of an unknown nature. Forensic science provides the most critical applications for their examination. Chemical tests, analytical methods, and techniques to process the evidence must be carefully selected by the forensic scientist. Ideally, it may be interpreted, analyzed, and judged in the original context of the crime scene. In this sense, hyperspectral imaging (HSI) has been employed as an analytical tool that maintains the integrity of the samples/objects for multiple and sequential analysis and for counter-proof exams. This paper is an overview of forensic science trends for the application of HSI techniques in the last ten years (2011–2021). The examination of documents was the main area of exploration, followed by bloodstain analysis aging process; trace analysis of explosives and gunshot residue. Chemometric tools were also addressed since they are crucial to obtain the most important information from the samples. There are great challenges in applying HSI in forensic science, but there have been clear technological and scientific advances, and a solid foundation has been built for the use of HSI in real-life cases. [ABSTRACT FROM AUTHOR]

A thermal desorption FF-TG-GC/MS method with a cycle time of just 164 s including cryofocusing, thermal desorption, analyte separation and system cool down was developed for the analysis of ten explosives and six chemical warfare agent (CWA) simulants. Sampling was carried out both in liquid and gaseous form using micro thermal desorption tubes (μ TD-tubes, 1.4 mm I.D., 10 mg Tenax TA). In addition to the desorption conditions, the effects of deactivated μ TD-tubes, the spatial temperature gradient along the separation column and additional cryofocusing to refocus the analytes were evaluated. Limits of detection between 0.17 and 9.18 ng/ μ L and R 2 values ≥ 0.983 for calibration curves (with the exception of PETN) were obtained. Relative standard deviations of mainly < 15% were achieved for within day repeatability. The fluctuations in the peak areas were mostly below 20% with between-day repeatability measured across three days. • Micro thermal desorption tubes and thermal desorption unit, with low thermal mass. • Enrichment by thermal desorption of explosives and chemical warfare agent simulants. • Optimization of desorption conditions (temperature, split) and method validation. • Impact of μ TD-tube deactivation, spatial temperature gradient on peak areas. • New application for flow field thermal gradient gas chromatography (FF-TG-GC). [ABSTRACT FROM AUTHOR]

This paper concerns a new method for projectile disposal by emptying the explosives in projectiles with electromagnetic heating. It explains the basic principles of the emptying technology via electromagnetic heating. A multiphysical analysis model coupled with an electromagnetic, thermal, fluid and phase transition model is established, and the explosive melting simulation is conducted based on this model. The dynamic phase transition process of the explosive from solid to liquid is simulated, and the electric field, magnetic field and thermal field distribution characteristics during the process are analyzed. Furthermore, the effect of excitation current characteristics on the phase transition of the explosive is given, which shows that the explosive melting process is controllable by setting the excitation current amplitude or frequency. This paper provides a new method for the disposal of end-of-life projectiles, which is more controllable, safe and environmentally friendly. [ABSTRACT FROM AUTHOR]

This study effectively synthesized N,N'-(diazene-1,2-diylbis(5-amino-[1,2,4]triazolo[1,5-a][1,3,5]triazine-2,7-diyl)) dinitramide (3) by using 3,5-diamino-1,2,4-triazole as a startingmaterial combining hydrogen bonds (HBs) and strong p-p stacking interaction between layers. Moreover, two fused rings were linked by an azo group to expand the conjugated compound, resulting ina shorter interlayerdistance. Thenewcompound and its energetic salts (4-6) were fully characterized through elemental analysis, IR spectroscopy, 1H and 13C NMR spectroscopy, and thermal analysis. The heats of formation and detonation properties of these compounds were calculated using Gaussian 09 and EXPLO5, respectively. Thecalculated results showthat compounds 3-6 have both lowimpact and friction sensitivities (IS>40 J; FS > 360 N) and favorable densities and detonation properties (?: 1.81-1.96 g·cm-3; vD: 7965-8248 m·s-1; p: 24.9-31.4 GPa). Therefore, they are promising candidates for high-energy and insensitive explosives. [ABSTRACT FROM AUTHOR]

The highly energetic 1-nitrimino-5-aminotetrazole moiety can be obtained by direct nitration of 1,5-diaminotetrazole. The hydroxylammonium, 3,6,7-triamino-[1,2,4]triazolo[4,3-b][1,2,4]triazolium (HTATOT) and potassium derivatives were synthesized in this study through acid-base reaction because of the expected promising properties. Especially the potassium derivative shows interesting characteristics for a use as primary explosive. All new compounds were characterized through multinuclear NMR and IR spectroscopy. The purities were checked via CHNO elemental analysis and the compounds' sensitivities (IS, FS, ESD) were measured using the BAM 1 of 6 method. Based on the crystallographic densities (low-temperature X-ray diffraction experiments) and the calculated heats of formation (atomization method based on CBS-4M level of theory), the performance data were calculated using the EXPLO5 code. The potassium derivative thereby shows interesting properties for possible use as metal-free primary explosive (positive PETN initiation, Td = 180 °C). The hydroxylammonium derivative shows astonishing detonation properties (vD = 9697 m·s°1, p = 38.1 GPa). [ABSTRACT FROM AUTHOR]

Two novel representatives of energetic (1,2,4-triazolyl)furoxans were prepared from the readily available (furoxanyl)amidrazones. Synthesized compounds were thoroughly characterized with IR and multinuclear NMR spectroscopy, elemental analysis and X-ray diffraction data. Analysis of structural features supported by quantumchemical calculations revealed the main reasons for experimentally observed difference in thermal stability and mechanical sensitivity of both compounds. It was found that 3-cyano-4-(1H-1,2,4-triazol-3-yl)furoxan is more thermally stable (Td: 229 °C) than 4-azido-3-(1H-1,2,4-triazol-3-yl)furoxan (Td: 154 °C) and the latter compound is also more sensitive to impact and friction. In addition, both heterocyclic assemblies have high detonation parameters (vD: 7.0-8.0 km·s°1; p: 22-29 GPa) exceeding those of benchmark explosives trinitrotoluene and hexanitrostilbene which enable their usability for various energetic applications. [ABSTRACT FROM AUTHOR]

In this work, a fused-ring tetrazolo[1,5-b]pyridazine frameworkwith catenated nitrogen chainwas applied to develop new energetic materials with task-specific applications for different purposes. Their syntheses, characterizations and properties were extensively studied. Among them, 6-methylnitramimo-7-nitro-8-aminotetrazolo[1,5-b]pyridazine (4) is a potential booster explosive with good detonation velocities (Dv: 8496ms-1), detonation pressure (p: 28.7 GPa), impact sensitivity (IS: 3 J), friction sensitivity (FS: 112 N) and better decomposition temperature (Td: 200.7 °C) than PETNaswell as suitable predicted shock sensitivity (p90%TMD: 1.839GPa). 6-Nitramimo-7-amino-8-nitrotetrazolo[1,5-b]pyridazine (12) is a high-energy explosive (Dv: 8926ms-1, p: 33.7 GPa), while bis((7-nitro-8-aminotetrazolo[1,5-b] pyridazin-6-yl)amino)ethane (9) is a heat-resistant explosive (Td: 303.1 °C) with high detonation performances (Dv: 8809ms-1, p: 29.3 GPa) and low sensitivities (IS: 19 J, FS: 288 N). The analysis of crystal structure, Hirshfeld surface, fingerprint plot, bond dissociation energies (BDEs) and electrostatic potentials (ESP) was used to assess the energy density and sensitivity properties. [ABSTRACT FROM AUTHOR]

• Probabilistic risk assessment for the protection of infrastructure from explosive attacks. • Terrorist threats and hazards, vulnerability, and consequences assessment. • Decision analysis for the optimal risk reduction for bridges and buildings. • Break even damage probabilities assessed for the Alternate Path Method. • Surveillance and bridge closure was more cost-efficient than structural protection. Attacks on infrastructure have been a common feature of terrorism over many decades. The weapon of choice is often a Vehicle-Borne Improvised Explosive Device (VBIED) or a person-borne or other type of IED. The consequences of a successful attack in terms of casualties, physical damage, and other direct and indirect costs including societal costs can be catastrophic. Protectives and other risk reduction measures can ameliorate the threat likelihood, vulnerability or consequences. There is a need for a rational approach to deciding how best to protect infrastructure, and what not to protect. Hence, this paper describes a probabilistic risk assessment for the protection of infrastructure from explosive attacks. This includes a description of terrorist threats and hazards, vulnerability assessment including progressive or disproportionate collapse, and consequences assessment. Illustrative examples of the decision analysis consider the optimal risk reduction and design strategies for bridges and the progressive collapse of buildings. [ABSTRACT FROM AUTHOR]

Deaths due to high end machineries like guns and sophisticated explosives are on increasing trends with throughout the world. Such deaths lead to high morbidity and mortality in the human society. The present study was conducted to explore various socio demographic characters of victims and medicolegal aspects related to firearm and explosive injuries death. This was a descriptive cross sectional autopsy based study of all firearm and bomb blast injury deaths brought to mortuary of Regional Institute of Medical Sciences, Imphal Manipur during the period from October 2013 to August 2015. In this study a total of 46 cases of firearm and explosives death during the study period was analysed in various medico-legal aspects. Rifled firearm and bomb blast was commonest weapon employed. Multiple injuries and head injuries were commonest cause of death. The trends of death might help the law enforcement authorities and Government to take proactive steps to curb this menace. [ABSTRACT FROM AUTHOR]

We have studied the dynamic spall process for copper samples in contact with detonating low-performance explosives. When a triangular shaped shock wave from detonation moves through a sample and reflects from the free surface, tension develops immediately, one or more damaged layers can form, and a spall scab can separate from the sample and move ahead of the remaining target material. For dynamic experiments, we used time-resolved velocimetry and x-ray radiography. Soft-recovered samples were analyzed using optical imaging and microscopy. Computer simulations were used to guide experiment design. We observe that for some target thicknesses the spall scab continues to run ahead of the rest of the sample, but for thinner samples, the detonation product gases accelerate the sample enough for it to impact the spall scab several microseconds or more after the initial damage formation. Our data also show signatures in the form of a late-time reshock in the time-resolved data, which support this computational prediction. A primary goal of this research was to study the wave interactions and damage processes for explosives-loaded copper and to look for evidence of this postulated recompression event. We found both experimentally and computationally that we could tailor the magnitude of the initial and recompression shocks by varying the explosive drive and the copper sample thickness; thin samples had a large recompression after spall, whereas thick samples did not recompress at all. Samples that did not recompress had spall scabs that completely separated from the sample, whereas samples with recompression remained intact. This suggests that the hypothesized recompression process closes voids in the damage layer or otherwise halts the spall formation process. This is a somewhat surprising and, in some ways controversial, result, and the one that warrants further research in the shock compression community. [ABSTRACT FROM AUTHOR]

The estimation of pressure and temperature histories, which are required to understand chemical pathways in condensed phase explosives during detonation, is discussed. We argue that estimates made from continuum models, calibrated by macroscopic experiments, are essential to inform modern, atomistic-based reactive chemistry simulations at detonation pressures and temperatures. We present easy to implement methods for general equation of state and arbitrarily complex chemical reaction schemes that can be used to compute reactive flow histories for the constant volume, the energy process, and the expansion process on the Rayleigh line of a steady Chapman-Jouguet detonation. A brief review of state-of-the-art of two-component reactive flow models is given that highlights the Ignition and Growth model of Lee and Tarver [Phys. Fluids 23, 2362 (1980)] and the Wide-Ranging Equation of State model of Wescott, Stewart, and Davis [J. Appl. Phys. 98, 053514 (2005)]. We discuss evidence from experiments and reactive molecular dynamic simulations that motivate models that have several components, instead of the two that have traditionally been used to describe the results of macroscopic detonation experiments. We present simplified examples of a formulation for a hypothetical explosive that uses simple (ideal) equation of state forms and detailed comparisons. Then, we estimate pathways computed from two-component models of real explosive materials that have been calibrated with macroscopic experiments. [ABSTRACT FROM AUTHOR]

When an explosive burns, gaseous products are formed as a result. The interaction of the burning solid and gas is not well understood. More specifically, the process of the gaseous product heating the explosive is yet to be explored in detail. The present work sets out to fill some of that gap using mathematical modelling: this aims to track the temperature profile in the explosive. The work begins by modelling single-step reactions using a simple Arrhenius model. The model is then extended to include three-step reaction. An alternative asymptotic approach is also employed. There is close agreement between results from the full reaction-diffusion problem and the asymptotic problem. [ABSTRACT FROM AUTHOR]

The verification of trace explosives detection systems is often constrained to small sample sets, so it is important to support the significance of the results with statistical analysis. As binary measurements, the trials are assessed using binomial statistics. A method is described based on the probability confidence interval and expressed in terms of the upper confidence interval bound that reports the probability of successful detection and its level of statistical confidence. These parameters provide useful measures of the system's performance. The propriety of combining statistics for similar tests—for example in trace detection trials of an explosive on multiple surfaces—is examined by statistical tests. The use of normal statistics is commonly applied to binary testing, but the confidence intervals are known to behave poorly in many circumstances, including small sample numbers. The improvement of the normal approximation with increasing sample number is shown not to be substantial for the typical numbers used in this type of explosives detection system testing, and binary statistics are preferred. The methods and techniques described here for testing trace detection can be applied as well to performance testing of explosives detection systems in general. [ABSTRACT FROM AUTHOR]

The use of Refuse Derived Fuel (RDF) has grown over the last 30 years due to its perception as a readily available Bio-fuel. This increased use of RDF, is closely shadowed by the growth of industrial fires and explosions, and these associated hazards require a rethink of fire and explosion protection/prevention processes at power plants. It is known that RDF fires are notoriously difficult to detect and extinguish when in enclosed storage spaces and can last for days, weeks or even months. Additionally, under conducive and aligned conditions, the effluent from RDF deep seated smouldering fires can lead to explosions. It is therefore necessary to review current practices within RDF pellet fuel handling & fuel storage, to prevent future accidents, and to make the industry as safe as possible. [ABSTRACT FROM AUTHOR]

One of the greatest challenges for explosive ordnance disposal operators is the disarming process of an improvised explosive device. These dangerous devices are often made from homemade explosive. Committing a bomb attack in urban areas is a basic weapon of terrorists, which may claim civilians' lives. The main aim of experts is to avoid any lethal attack and to stop terrorists who endanger our life. Identifying homemade explosives may also help during the fight against terrorism since information may be provided this way, which is essential for professionals who work in the areas of operations. Usage of high-tech equipment provides stable and reliable background in the field of explosives' analysis. [ABSTRACT FROM AUTHOR]

Chemical analysis of different materials at the place where analytes are present (on-site analysis) has several advantages in comparison to analysis of these materials after delivering the samples to laboratory. Mobile devices, possessing expected properties in terms of using energy, mass and volume are needed for such analyses. The obtained results should be comparable to those obtained with the stationary instruments. Mass and ion mobility spectrometers are examples of the instruments fulfilling these requirements. At the beginning, the article describes the developments in combining of mass and ion mobility spectrometers (MS, IMS) with miniature gas chromatographs (GC). Both systems are used for analyses in the field, mainly for determination of environmental pollutions. They are used not only for analysis of typical chemicals present in different environmental compartments (in air, water and soil samples) but also for analysis of explosives, drugs and chemical warfare agents when fast results are needed. Particularly noteworthy is their applications in space exploration on the International Space Station. The selected examples of applications of miniaturised GC-MS and GC-IMS devices are presented in the second part of this mini review. [ABSTRACT FROM AUTHOR]

The impact and shock sensitivity of porous (granular) high-explosives is related to the formation of small mass regions of elevated temperature within the material called hot-spots by dissipative mechanisms such as plastic and friction work. Because of their small size, hot-spots are difficult to experimentally interrogate, particularly for high volumetric strain rates (εV>10,000 s-1). In this study, simulations are performed for large ensembles of deformable particles (≈4000 particles) using a combined finite and discrete element technique to characterize statistical distributions of hot-spot intensity, geometry, and spatial proximity within and behind quasi-steady, piston supported uniaxial waves in granular HMX (C4H8N8O8). Emphasis is placed on examining how the material's initial particle packing density, characterized by its effective solid volume fraction [lowercase_phi_synonym]s,0, affects hot-spot statistics for pressure dominated waves corresponding to piston speeds within the range 300≤Up≤500 m/s. Predictions indicate that hot-spot intensity is only marginally affected by initial porosity (1-[lowercase_phi_synonym]s,0) for all piston speeds, whereas hot-spot size, number density, volume fraction, and volume specific surface area appreciably increase with porosity and exponentially increase with piston speed. Minor variations in particle shape are predicted to be largely inconsequential. Joint distributions of hot-spot intensity and size are combined with thermal explosion data to identify and examine critical hot-spots that quickly react behind waves. These results indicate that the observed increase in sensitivity with initial porosity for sustained loading is likely due to an increase in hot-spot size and number rather than intensity. [ABSTRACT FROM AUTHOR]

A system for detecting explosives in walls based on the tagged neutron method was established. An associated particle neutron generator ING-27 developed by the All-Russian Research Institute of Automatics (VNIIA) is used as the neutron source, two yttrium lutetium silicate (LYSO) detectors are used for the γ detector, and a silicon detector is used as the α detector. The α-γ coincidence spectra of 300 g ammonium nitrate and TNT samples placed behind 10 cm concrete wall were measured. A neural network algorithm was applied to analyze the data. Through fine selection of time windows of α-γ coincidence spectra, the counts of full-energy peak of N, C and O elements and their proportions are selected as the input eigenvectors. The neural network is trained by the experimental data obtained by this system. Through training, eight groups of test data consisting of 32 γ-ray spectra were identified, and a 98.7% of correct detection rate was achieved. [ABSTRACT FROM AUTHOR]

Precise analysis of explosives is important for environmental pollution evaluation and terrorist prevention. However, rapid assay of explosives with high selectivity and sensitivity remains difficult. Here, we show that the gold nanocluster-modified metal-organic frameworks are excellent optical probes for explosive detection. The nanoclusters exhibit enhanced luminescence and selectively respond toward 2,4,6-trinitrotoluene over other explosives with a detection limit of 5 nM and fast response within 1 min. The efficient assay is resulted from the framework-mediated cluster aggregation and TNT binding. Gold nanocluster-modified metal-organic frameworks exhibit enhanced luminescence and serve as sensitive optical probes for selective and rapid detection of TNT. Image 1 • Facilely functionalized gold nanoclusters with enhanced luminescence were successfully synthesized. • Gold nanoclusters incorporated ZIF-8 showed rapid response to TNT within 1 min. • The fluorescent probe exhibited highly sensitive and selective sensing toward TNT over other explosives. [ABSTRACT FROM AUTHOR]

When considering incident investigations and security checks focused on energetic materials, there is an ongoing need for rapid, on-scene chemical identification. Currently applied methods are not capable of meeting all requirements, and hence, portable mass spectrometry is an interesting alternative although many instrumental challenges still exist. To be able to analyze explosives with mass spectrometry outside the traditional laboratory, suitable ambient ionization methods need to be developed. Ideally such methods are also easily implemented in the field requiring limited to no power sources, gas supplies, flow controllers, and heating devices. For this reason, the potential of SAWN (surface acoustic wave nebulization) for the ambient ionization and subsequent mass spectrometric (MS) analysis of organic explosives was investigated in this study. Excellent sensitivity was observed for nitrate-based organic explosives when operating the MS in negative mode. No dominant adduct peaks were observed for the peroxides TATP and HMTD with SAWN-MS in positive mode. The MS spectra indicate extensive fragmentation of the peroxide explosives even under the mild ionization conditions provided by SAWN. The potential of SAWN-MS was demonstrated with the correct identification of nitrate-based organic explosives in pre- and post-explosion case samples in only a fraction of the time and effort required for the regular laboratory analysis. Results show that SAWN-MS can convincingly identify intact organic energetic compounds and mixtures but that sensitivity is not always sufficient to detect traces of explosives in post-explosion residues. [ABSTRACT FROM AUTHOR]

To prevent catastrophic asteroid–Earth collisions, it has been proposed to use nuclear explosives to deflect away earthbound asteroids. However, this policy of nuclear deflection could inadvertently increase the risk of nuclear war and other violent conflict. This article conducts risk–risk tradeoff analysis to assess whether nuclear deflection results in a net increase or decrease in risk. Assuming nonnuclear deflection options are also used, nuclear deflection may only be needed for the largest and most imminent asteroid collisions. These are low‐frequency, high‐severity events. The effect of nuclear deflection on violent conflict risk is more ambiguous due to the complex and dynamic social factors at play. Indeed, it is not clear whether nuclear deflection would cause a net increase or decrease in violent conflict risk. Similarly, this article cannot reach a precise conclusion on the overall risk–risk tradeoff. The value of this article comes less from specific quantitative conclusions and more from providing an analytical framework and a better overall understanding of the policy decision. The article demonstrates the importance of integrated analysis of global risks and the policies to address them, as well as the challenge of quantitative evaluation of complex social processes such as violent conflict. [ABSTRACT FROM AUTHOR]

• A filter paper chad was used to extract explosive residues from vapor samples. • The extracted explosives were analysed via Lab on a Chip. • Results between vapor and liquid samples were compared. • A new promising method to detect explosives in the headspace is described. The detection and analysis of explosives and explosive-related compounds is a heightened priority in recent years for homeland security and counter-terrorism applications. This study aimed to evaluate the use of a commercial Lab-On-a-Chip (LOC) instrument for the analysis of explosive vapours, with the long-term goal of developing a portable instrument for passively detecting explosives in air samples. A simple method to collect explosive vapour residues was developed using a glass vial containing varying amounts of the target explosives (1 mg/mL). Standards were diluted to the desired concentration in 150 μL of acetone to facilitate the evaporation. The top of the vial was covered with a circular 0.5 cm diameter filter paper and exposed to a range of temperatures from 22 °C to 80 °C for 15 min. Following evaporation, the filter paper chads were folded and inserted into the LOC wells containing the separation buffer for the analysis, avoiding any further extraction step. After successfully separating and detecting eight explosives via liquid analysis, three explosives were chosen as targets for the vapour analysis experiments. 1,3,5-Trinitrobenzene (TNB), 2,4,6-Trinitrotoluene (TNT), and 2,4,6-Trinitrophenylmethylnitramine (Tetryl) were successfully separated, detected and identified following the vapour extraction of explosive standards onto filter paper chads. Limits of detection for the liquid analysis were demonstrated to be 2.32 ng for TNB, 2.35 ng for Tetryl, and 3.25 ng for TNT. The minimum detectable mass found for the vapour analysis was 6.03 for TNB, 9.99 ng for TNT, and 14.22 ng for Tetryl. The average recovery from the paper chads was 29% for Tetryl, 47% for TNB, and 75% for TNT (n = 4), comparable with findings from previous studies. Results show that a minimum temperature of 40 °C is necessary to vaporize the compounds using acetone, while the best results were achieved when heating the vial to 80 °C. The use of a filter paper to collect the explosives residues, avoiding any additional extraction step, and the ability to analyze these compounds using a LOC instrument, makes this approach a future alternative method for explosive residues detection in the headspace. [ABSTRACT FROM AUTHOR]

Abstract A novel method for the detection of vaporous products was developed utilizing a derivatizing agent collected onto a cryo-cooled gas chromatograph (GC) inlet, with analysis by gas chromatography-mass spectrometry (GC-MS). The technique was applied to the detection of ammonia, which has been difficult to detect at trace levels, particularly in the presence of other chemical interferents, due to its small mass and high volatility. To address this, the ammonia is derivatized in the inlet with butyl chloroformate to produce butyl carbamate, a compound that is retained by GC columns and compatible with standard GC-MS analysis. This method was then used to quantify the ammonia headspace vapor concentration produced from the dissociation of bulk ammonium nitrate as well as from mixtures with aluminum and petroleum jelly, which are fuels commonly used in homemade explosives (HMEs). Graphical abstract fx1 Highlights • Trace ammonia is difficult to detect in the presence of chemical interferents. • A novel method for online detection of ammonia vapor by GC-MS was developed. • Ammonia was derivatized with butyl chloroformate in the cryo-cooled GC inlet. • Using this method, ammonium was quantified from ammonium nitrate explosive materials. [ABSTRACT FROM AUTHOR]

This work introduces laser induced breakdown spectroscopy (LIBS) as a novel, cheap and non‐destructive method to study the changes of mechanical properties of plastic bonded explosives (PBX) during their aging. Accelerated aging was used in three different temperatures 60, 70, and 80 °C to obtain different aged samples. The measurements of mechanical properties analysis were also done on the aged samples to validate the resulted data from LIBS spectroscopy. LIBS tests were done in both air and argon atmosphere, in which molecular bands such as CN and C2 radiation were compared for all aged samples. In order to more accurate discrimination between spectra of different samples, principal component analysis (PCA) was used as a suitable chemometric method. All these results represent the changes in the chemical structure of specimens, which are due to increasing time and temperature during their aging processes. [ABSTRACT FROM AUTHOR]

Generate compress‐shear loading on Polymer Bonded Explosive (PBX) specimens. The research was carried out to determine the pressure and macroscopic temperature variation occurring in the specimen by using a pressure sensor and a thermocouple. High‐speed photography was used to reveal the macroscopic ignition phenomena. X‐ray diffraction (XRD) was used to study the material composition of raw and recovered specimens. The results of the experiments described here clearly show that specimens underwent crush, melt and ignition from impact to reaction. At the same time, the relative content of aluminium decreased. Compared to the direct impact results from split Hopkinson compression‐shear bar tests, the drop‐weight loading pulse is longer, so PBX specimens ignite more easily. [ABSTRACT FROM AUTHOR]

The plate dent test is one of the simplest tools for fast determination of the detonation pressure. The test is based on the observation that the detonation pressure correlates with the depth of the dent produced by a detonating explosive on a metal witness plate. The present study is aimed at developing a model for estimating the dent depth, which is used not only to obtain the detonation pressure, but also to evaluate the brisance relative to a reference explosive. It is shown that the experimental dent depth values for CHNO and CHNOClF explosives can be successfully reproduced by a model based on few parameters, namely: loading density, number of moles of gaseous detonation products per gram of the explosive, and average molecular weight of the gaseous products, where the number of moles and the mean molecular weight of the gaseous products are calculated according to the [H2O-CO2] arbitrary decomposition assumption. Furthermore, the predicted values of the dent depth and the Kamlet-Jacobs method are used to estimate the detonation pressure for 37 explosives. The results show that the pressures obtained on the basis of the dent depth values are in better agreement with experimental/thermochemical code data than the predictions of the Kamlet-Jacobs method. [ABSTRACT FROM AUTHOR]

Partially burned smokeless powder particles may be present as a form of evidence following a shooting or explosive event, such as the explosion of a pipe bomb. The characterization and classification of residual smokeless powers may allow for a known sample, i.e. sample collected from a suspect, to be connected to an unknown sample, i.e. sample obtained from a crime scene. In this study, thirty-four (34) smokeless powders were analyzed using GC-MS and DART-TOFMS to determine how comparable the discriminatory power of each instrument was based on the smokeless powder constituents identified within each sample. Analysis of smokeless powders by DART-TOFMS generated comparable results to GC-MS in a fraction of the time (∼30seconds). Most peaks observed between the instruments were the same; however, N-nitroso-DPA was only observed in the DART-TOFMS spectra but was not a significant contributor. Samples were naturally grouped together using hierarchical cluster analysis and principal component analysis, based on underlying features in the resulting spectra. Samples were placed into groupings based on significant peaks observed and relative intensities. Classification models were presented for both GC-MS and DART-TOFMS and subsequently tested and compared. The classification models used in this study were linear discriminant analysis, k-nearest neighbors, and random forest modeling. The groups observed were similar between the two instruments, indicating that DART-TOFMS provides comparable data to GC-MS and could be used as a rapid screening technique. [ABSTRACT FROM AUTHOR]

Abstract Polymer-bonded explosives (PBXs) are often subjected to different external environmental conditions with various temperature and humidity during long-term storage, transportation, and usage process. The change in temperature and humidity will result in PBXs cracks formation and cause higher risk of explosion evolution when undergoing various stimulus including impact or friction. Herein, a self-healing polymer binder is developed to solve this problem. The fluoropolymer gel binder, a PVDF-co-HFP (copolymer of CH 2 -CF 2 and CF 2 -CF(CF 3))/EMIOTf (1-ethyl-3-methylimidazolium trifluoromethanesulfonate)/graphene ternary composite, has high density, high thermal conductivity, excellent interfacial adhesion property, and exhibits self-healing ability at room temperature. Highly filled PBXs composites with 95% of explosive 2, 6-diamino-3, 5-dinitropyrazine-1-oxide (LLM-105) and 5% of ternary composite are fabricated. The as-prepared PBX samples have high denotation parameter (7800 m s−1), low impact sensitivities (11–12 J), and low friction sensitivity (no sparks was observed even at friction energy load of 0.36 N). More importantly, our PBXs have effective crack healing ability within 48 h at room temperature. Therefore, the stability and safety of PBXs are improved through the self-healing polymer binder. Such PBXs can find widespread application in various military and civil fields. [ABSTRACT FROM AUTHOR]

Abstract The effect of heat treatment at 903 K on microstructure and intermetallic compound growth in explosively welded A1050/Ti gr. 2/A1050 clad was presented in the paper. Growth kinetics of TiAl 3 intermetallic layers formed at upper and lower interfaces of three-layered A1050/Ti gr. 2/A1050 was investigated. A new approach to definition of growth kinetics of TiAl 3 intermetallic phase was discussed. It was established that the growth was solely governed by grain boundary diffusion at the upper interface. Change of the mechanism from grain boundary diffusion to volume diffusion was observed at the lower interface. [ABSTRACT FROM AUTHOR]

Abstract: To improve the groove charge density and reduce the initiation synchronicity error of a multi‐point initiation explosive network, CL‐20/NC and HMX/NC polymer‐bonded explosives (PBXs) with 95 wt.% ultrafine CL‐20 or ultrafine HMX as main explosive, with 5 wt.% NC as binder, were prepared. The morphology and crystal of the two PBXs was characterized in scanning electron microscopy, X‐ray diffractometry, and Fourier‐transform infrared spectroscopy. The critical dimension for linear detonation is 0.9 mm for the CL‐20/NC PBX and 1.5 mm for the HMX/NC PBX, and with the detonation velocity of the former being 36.2 % higher than the latter. Hence, the CL‐20/NC PBX was selected as groove charge for the multi‐point initiation explosive network. An explosive network charging method is proposed that involves groove press‐loading charging with three pre‐pressed booster pellets as output end charges. This configuration increases the density of the booster charge in the grooves to 1.880 g ⋅ cm−3 (94 % of theoretical density), effectively improving the charging density consistency and lowering the network initiation synchronicity error to less than 100 ns. The rod‐shaped explosively formed projectile has a small lateral offset and good shape indicating that the synchronization of the optimized explosive network meets the requirement of a selectable shaped charge projectile. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a systematic method to determine and test the ignition and growth reactive flow model parameters of a new energetic material PBX 1314 (60 weight % RDX, 16 weight % aluminum and 24 weight % HTPB) is presented. Cylinder test and shock initiation experiments are performed to study the shock initiation property of the explosive. Ignition and growth parameters are determined based on the experimental data. Test of the obtained parameters is performed by the comparison of the reaction fraction in the impact initiation and energy release experiments and the corresponding numerical simulations. The simulation results reveal that the proceeding of reaction and energy release are unsteady and inhomogeneous. Pressure decline quenches the reaction in the impact layer of the specimen although the impact pressure is more than 7 GPa. Wave reflection and superposition strengthen the pressure in the top of the specimen and triggers detonation. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve the detonation performances of emulsion explosives, a new type of emulsion explosives sensitized by hydrogen‐storage glass microballoons is proposed. The influences of hydrogen in glass microballoons on explosion characteristics of emulsion explosives were studied. Brisance testing and underwater explosion experiments showed that, compared with traditional emulsion explosives, the shock impulse and specific total energy of hydrogen‐storage glass microballoons sensitized emulsion explosives are improved significantly. The brisance (compression of lead block) of hydrogen‐storage emulsion explosives is 23.0 mm, 3.2 mm more than that of traditional emulsion explosives. Therefore, the hydrogen‐storage glass microballoons could be a promising energetic additive for developing high‐power emulsion explosives. [ABSTRACT FROM AUTHOR]

This novel investigation focused on studying the transfer of explosive residues (TNT, HMTD, PETN, ANFO, dynamite, black powder, NH 4 NO 3 , KNO 3 , NaClO 3 ) in ten consecutive fingerprints to two different surfaces – cotton fabric and polycarbonate plastic – by using multispectral imaging (MSI). Imaging was performed employing a reflex camera in a purpose-built photo studio. Images were processed in MATLAB to select the most discriminating frame – the one that provided the sharpest contrast between the explosive and the material in the red-green-blue (RGB) visible region. The amount of explosive residues transferred in each fingerprint was determined as the number of pixels containing explosive particles. First, the pattern of PETN transfer by ten different persons in successive fingerprints was studied. No significant differences in the pattern of transfer of PETN between subjects were observed, which was also confirmed by multivariate analysis of variance (MANOVA). Then, the transfer of traces of the nine above explosives in ten consecutive fingerprints to cotton fabric and polycarbonate plastic was investigated. The obtained results demonstrated that the amount of explosive residues deposited on successive fingerprints tended to undergo a power or exponential decrease, with the exception of inorganic salts (NH 4 NO 3 , KNO 3 , NaClO 3 ) and ANFO (consists of 90% NH 4 NO 3 ). [ABSTRACT FROM AUTHOR]

Ion mobility spectrometry (IMS) which acts as a rapid analysis technique is widely used in the field detection of illicit drugs and explosives. Due to limited separation abilities of the pint-sized IMS challenges and problems still exist regarding high false positive and false negative responses due to the interference of the matrix. In addition, the gas-phase ion chemistry and special phenomena in the IMS spectra, such one substance showing two peaks, were not identified unambiguously. In order to explain or resolve these questions, in this paper, an ion mobility spectrometry was coupled to a mass spectrometry (IMS-MS). A commercial IMS is embedded in a custom-built ion chamber shell was attached to the mass spectrometer. The faraday plate of IMS was fabricated with a hole for the ions to passing through to the mass spectrometer. The ion transmission efficiency of IMS-MS was optimized by optimizing the various parameters, especially the distance between the faraday plate and the cone of mass spectrum. This design keeps the integrity of the two original instruments and the mass spectrometry still works with multimode ionization source (i.e., IMS-MS, ESI-MS, APCI-MS modes). The illicit drugs and explosive samples were analyzed by the IMS-MS with 63 Ni source. The results showed that the IMS-MS is of high sensitivity. The ionization mechanism of the illicit drug and explosive samples with 63 Ni source were systematically studied. In addition, the interferent which interfered the detection of cocaine was identified as dibutyl phthalate (DBP) by this platform. The reason why the acetone solution of amphetamine showed two peaks was explained. [ABSTRACT FROM AUTHOR]

A near infrared (NIR) optical biosensor based on peptide functionalized single-walled carbon nanotubes (SWCNTs) hybrids for 2,4,6-trinitrotoluene (TNT) explosive detection was developed. The TNT binding peptide was directly anchored on the sidewall of the SWCNTs using the π-π interaction between the aromatic amino acids and SWCNTs, forming the peptide-SWCNTs hybrids for near infrared absorption spectra measurement. The evidence of the morphology of peptide-SWCNTs hybrids was obtained using atomic force microscopy (AFM). The results demonstrated that peptide-SWCNTs hybrids based NIR optical biosensor exhibited sensitive and highly selective for TNT explosive determination, addressing a promising optical biosensor for security application. [ABSTRACT FROM AUTHOR]

In some novel warheads, the explosive charge is not compactly filled within the cylindrical casing but has a hollow core instead. However, most existing formulas can only predict the fragment velocity of warheads fully filled with explosive charge. In this work, through theoretical analysis and numerical simulations, a new formula was proposed to predict the initial fragment velocity of novel warheads with hollow core. The formula was built on top of the Gurney formula and made use of a correctional function to account for the effects of the rarefaction wave from the hollow core of the explosive charge on the fragment velocity. The formula showed good agreement with the experimental results in the validation tests. Hence, the proposed formula is suitable for predicting the initial fragment velocity of warheads with hollow core. [ABSTRACT FROM AUTHOR]

Peroxide-based explosives (PBEs) are increasingly common in criminal and terrorist activity due to their easy synthesis and high explosive power. The rise in terrorist attacks involving PBEs has heightened the importance of detecting trace amounts of explosive residue or vapors. This paper aims to provide a review on the developments of techniques and instruments for detecting PBEs over the past ten years, specifically discussing advancements in ion mobility spectrometry, ambient mass spectrometry, fluorescence techniques, colorimetric methods, and electrochemical methods. We provide examples to illustrate their evolution and focus on new strategies for improving detection performance, specifically in terms of sensitivity, selectivity, high-throughput, and wide explosives coverage. Finally, we discuss future prospects for PBE detection. It is hoped this treatment will serve as a guide to the novitiate and as aid memoire to the researchers. [Display omitted] • Ion mobility spectrometry has been extensively deployed at screening points. • Mass spectrometry is considered the next-generation deployable system for field analysis of target explosives. • Fluorescent techniques show their potentials for the detection of explosives. • Colorimetric sensors also show the potential for the detection of explosives. • Electrochemical sensors also show the potential for the detection of explosives. [ABSTRACT FROM AUTHOR]

Explosives analysis has a significant practical application in the areas of national public security, anti-terrorism, stability maintenance, criminal investigation, national defense and military industry, and environmental protection. There may be some restrictions for conventional explosive detection and analytical techniques, such as excessive sample preparation complexity or specific security issues. However, laser-induced breakdown spectroscopy (LIBS) has several promising advantages, including easy sample pretreatment, trace substance identification, rapid analysis speed and standoff detection, and has been used in explosive analysis. This review summarizes the basic principles of LIBS and its development and application in the field of hazardous explosives in recent years. In more detail, it introduces the identification of inorganic and organic explosives under the interference of various substances, fingerprint identification of explosives, and standoff detection of explosives. It also includes using LIBS and laser-induced air shock from energetic materials technique to predict the potential performance of explosives (detonation velocity, the heat of combustion, detonation energy, detonation pressure, etc.). Finally, some future directions for LIBS are proposed. It will help readers to better understand the current research status of the LIBS technique in explosive analysis. • The recent advances in laser-induced breakdown spectroscopy for explosive analysis is presented. • This section of the review includes the basic principles of LIBS, experimental conditions, and data processing methods. • This review introduces the identification and prediction of potential properties of explosives using LIBS techniques. [ABSTRACT FROM AUTHOR]

The inerting effect of crystalline II type Ammonium Polyphosphate (APP-II) on explosion characteristics of micron-size Acrylates Copolymer (ACR) powders was experimentally studied. The inerting mechanism was analysed by combining thermogravimetry (TG) and differential scanning calorimetry (DSC) tests. The results indicated that the maximum explosion pressure ( P max ) and explosion index ( K st ) was 10.4 bar and 416 bar m/s, respectively for ACR powders. The minimum explosion concentration (MEC) of ACR powders ranged from 20 to 30 g/m 3 , and the experimental minimum ignition energy (MIE) of the ACR dust cloud was 10 mJ. Therefore, ACR dust was determined to be severely combustible dust. There existed a minimum inerting concentration (MIC), and the explosion of ACR powders can be inerted completely by 80 wt% APP-II. Furthermore, 30 and 40 wt% APP-II had a significant inerting effect on the MIE of ACR dust. According to TG and DSC tests, thermal stability of ACR would be augmented by the introduction of APP-II. The addition of APP-II triggered lower maximum mass loss rate (MMLR), higher temperature corresponding to mass loss of 90% ( T 0.1 ), chars yield, and endothermic peaks. Consequently, the ACR dust explosion was inerted by the chemical interaction of ACR/APP-II mixtures and endothermic decomposition of APP-II. [ABSTRACT FROM AUTHOR]

The explosion caused by detonation of explosive materials is followed by release of a large amount of energy. Whereby, a greater part of energy is used for rock destruction, and part of energy, in the form of seismic wave, is lost in the rock mass causing rock mass oscillation. Investigations of the character and behavior of the pattern of seismic wave indicate that the intensity and nature of the seismic wave are influenced by rock mass properties, and by blasting conditions. For evaluation and control of the seismic effect of blasting operations, the most commonly used equation is that of M.A. Sadovskii. Sadovskii's equation defines the alteration in the velocity of rock mass oscillation depending on the distance, the quantity of explosives, blasting conditions and geological characteristics of the rock mass, and it is determined based on trial blasting for a specific work environment. Thus, this paper offers analysis of the method for determination of parameters of the rock mass oscillation equation, which are conditioned by rock mass properties and blasting conditions. Practical part of this paper includes the experimental research carried out at Majdanpek open pit, located in the northern part of eastern Serbia and the investigations carried out during mass blasting at Nepričava open pit, located in central Serbia. In this paper, parameters n and K from Sadovskii's equation were determined in three ways--models in the given work environment. It was noted that, in practice, all three models can be successfully used to calculate the oscillation velocity of the rock masses. [ABSTRACT FROM AUTHOR]

This paper investigates the use of a suitable gamma detector array to increase the detectably of explosives in a prompt-gammas neutron activation analysis (PGNAA) system. Monte Carlo simulations (MCNP-4C) were used for analyzing the system. It was found that the system's performance is enhanced by the use of four detectors: three of the are located on the same side as the neutron source and the fourth on the opposite side. Signature-based radiation-scanning, with nine signatures for each detector, is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Thermal desorption based enrichment is a general concept that can enhance any detection system's sensitivity and selectivity. Given their large interior surface area and chemical versatility, archetype metal–organic frameworks (MOFs) are selected for preconcentration of explosives and their precursors occurring in low concentrations, and are compared to the state‐of‐the‐art sorbent Tenax TA. Applying inverse gas chromatography (iGC), this study shows that several archetype MOFs, namely HKUST‐1 and MIL‐53, surpass Tenax regarding their specific retention volume for nitromethane, a typical ingredient in improvised explosives. Using linear hydrocarbons as reference probe molecules, the dispersive surface energy is determined for all MOFs along with the specific contribution of the nitro group for HKUST‐1 and ZIF‐8. Trends from pulse‐chromatographic iGC‐investigations are mostly followed in breakthrough and thermal desorption experiments using a 1000 ppm nitromethane source. In these experiments, HKUST‐1 proves the peak substance, with enrichment factors being 109‐fold higher than for Tenax, followed by MIL‐53. In case of HKUST‐1, this factor is successfully reproduced for a 1 ppm concentration scenario. This shows that archetype MOFs can be suitable or even superior candidates for a sensitive sensing of nitroalkane explosives from the gas phase by a concept of preconcentration. [ABSTRACT FROM AUTHOR]

Azapropellanes are of great interest in many disciplines, including materials science and medicinal chemistry. Various synthetic approaches for azapropellanes have been explored; however, the synthetic study of the polyazapropellane skeleton containing five or more nitrogen atoms is rare. Here, we report a simple yet highly efficient protocol for the synthesis of the hexaaza[3.3.3]propellane skeleton as a building block for high energy materials for the first time. The key reactions include the Boc 2 O-assisted cyclization of glycoluril diamine without a column purification step and the first full reduction of all the three carbonyl groups to the methylene groups through a combination of LiAlH 4 and DIBAL-H. All the structures were confirmed by spectroscopic and X-ray analyses. [ABSTRACT FROM AUTHOR]

A multifunctional IR parametric laser system is developed and tested for remote detection and identification of atmospheric gases, including explosive and chemically aggressive substances. Calculations and experimental studies of remote determination of the spectroscopic parameters of the best known explosive substances TNT, RDX, and PETN are carried out. The feasibility of high sensitivity detection (~1 ppm) of these substances with the aid of a multifunctional IR parametric light source by differential absorption and scattering is demonstrated. [ABSTRACT FROM AUTHOR]

A damage elasto-viscoplastic model has been developed for cyclotetramethylenetetranitramine (HMX) crystals, which considers the anisotropy nature of HMX crystals and dislocation-mediated plasticity as well as the cleavage damage. A damage viscoelastic model has been developed for the polymer binder and the interface, which captures rate dependent damage due to binder rupture and binder debonding during the loading process. The proposed models were implemented in the finite element code ABAQUS by the user subroutine VUMAT. Macroscopic mechanical response s of Polymer Bonded explosives (PBXs) 9501 homogenized across the microstructure is generally in agreement with Split Hopkinson Pressure Bar (SHPB) experimental stress-strain response s at the strain rate of 2000 s −1 . Microstructural heterogeneity is responsible for the non-uniform stress, strain and damage fields. Crystal fracture is the dominant failure mechanism under dynamic compression while interfacial debonding plays a more important role under dynamic tension. Mesoscale modeling results along with macroscopic responses are significantly important to have a better understanding of deformation, damage and failure mechanisms of PBX samples under dynamic loading and to improve our predictive ability. [ABSTRACT FROM AUTHOR]