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At least 109 records · Page 6Linked to original sources

PubMed2005

Simple empirical method for prediction of impact sensitivity of selected class of explosives.

A new approach is described in this work to predict impact sensitivity of a variety of polynitroaliphatics, polynitroaromatics and the explosives containing N-NO2. This paper introduces some simple correlations for prediction of impact sensitivity of C(a)H(b)N(c)O(d) explosives using a, b, c, d, molecular weight and structure information of the explosive. The new correlations are applied to test different polynitroaromatics, benzofuroxans and nitramines. The results are compared with experimental data and some models of complex quantum mechanics computation. Predicted impact sensitivities for 46 explosives have a root mean square (rms) of deviation from experiment of 24 cm, which show good agreement with respect to measured values as compared to five different quantum mechanical models. Impact sensitivities for 58 polynitroaliphatics and related explosives are also calculated, and have a rms deviation from experiment of 40 cm.

Empirical Research↗

PubMed2005

The simplest method for calculating energy output and Gurney velocity of explosives.

Two correlations are introduced for calculating Gurney velocity as a useful parameter for thermochemical estimation of explosive energy output. For CaHbNcOd explosives, only the chemical composition of high explosive as well as its condensed or estimated gas phase heat of formation, which later is calculated by group additivity rules, is needed for calculating Gurney velocity. The introduced simple correlations in the present work may be applied to any explosive that contains the elements of carbon, hydrogen, nitrogen and oxygen with no difficulties at any loading density. There is no need to use any assumed decomposition reaction in present work. Gurney velocity are calculated for different pure and explosive formulations and compared with measured Gurney velocity at specified loading density. The results show that the agreement is good for present method as compared to previous correlations.

Explosions↗

PubMed1983

Micro-explosion cystolithotripsy.

According to the newly established method of micro-explosion lithotripsy, a cystolithotriptor with an explosive catheter, the tip of which was charged with 5 mg. lead azide explosives, was developed. In 3 clinical cases bladder stones from 32 to 65 mm. in diameter were crushed successfully into several fragments by 1 to 8 explosions using the cystolithotriptor. The fragments then were smashed into grains with Young's cystoscope and washed out by aspiration. This success may prove the usefulness of micro-explosion lithotripsy, which also may be introduced for the treatment of calculi in other organs in the future.

Adult↗

PubMed1998

A novel source of carbon monoxide poisoning: explosives used in construction.

We describe an incident of carbon monoxide (CO) poisoning caused by CO migrating through soil after nearby detonation of explosive charges. Employees worked in a newly installed, unconnected manhole without incident and finished shortly before underground explosives were detonated 50 feet south of the manhole to break up rock and soil. A worker entering the manhole 45 minutes after the explosion collapsed within minutes, as did two coworkers who rescued him. One worker died, and all had elevated levels of carboxyhemoglobin. Air samples collected from the manhole 2 days after the incident showed 1,910 ppm CO; in laboratory detonations, sample explosive yielded 27 L CO per kilogram detonated. We believe the CO in this incident was released from the nearby explosion and migrated through soil and fractured rock into the manhole. The blasting and construction industries should be made aware of this previously unrecognized route of CO exposure. Additionally, confined-space procedures and training are needed to prevent future accidents.

Accidents, Occupational↗

PubMed2000

Developments in vapour cloud explosion blast modeling.

TNT Equivalency methods are widely used for vapour cloud explosion blast modeling. Presently, however, other types of models are available which do not have the fundamental objections TNT Equivalency models have. TNO Multi-Energy method is increasingly accepted as a more reasonable alternative to be used as a simple and practical method. Computer codes based on computational fluid dynamics (CFD) like AutoReaGas, developed by TNO and Century Dynamics, could be used also in case a more rigorous analysis is required. Application of the Multi-Energy method requires knowledge of two parameters describing the explosion: a charge size and a charge strength. During the last years, research has led to an improved determination of the charge strength (i.e., the class number or source overpressure) to be chosen to apply the blast charts. A correlation has been derived relating the charge strength to a set of parameters describing the boundary conditions of the flammable cloud and the fuel in the cloud. A simple approach may not be satisfactory in all situations. The overpressure distribution inside a vapour cloud explosion is generally not homogeneous and the presence of obstructions causes directional blast propagation in the near field. A CFD approach, in which the actual situation is modeled, supplies case-specific results. An overview of the key aspects relevant to the application of the Multi-Energy method and CFD modeling is provided. Then the application of the two methods is demonstrated for an example problem involving the calculation of the explosion blast load on a structure at some distance from the explosion in an offshore platform complex.

Air Pollution↗

PubMed2002

The digital radiographic and computed tomography imaging of two types of explosive devices.

Two well-established medical imaging methods, digital radiography (DR) and computed tomography (CT), were employed to obtain images of two types of explosive devices, model rocket engines and shotgun shells. The images were evaluated from an airport security perspective. In terms of geometrical shape, the detection probability of the explosive devices appears to be higher with DR imaging, but in terms of the actual explosive compounds in the devices, CT appears to offer a higher detection probability. DR imaging offers a low detection probability for the explosive powder in the shotgun shells, but a rather significant detection probability for the explosive propellant in the model rocket engines.

Explosions↗

PubMedDate not supplied

Preliminary investigation into the recovery of explosives from hair.

Sampling of hair has proved to be a useful non-invasive method for detecting illicit drugs. This study examined the viability of hair as a surface from which explosive traces can be recovered and showed that as little as one-hour vapour exposure can result in measurable traces of explosives. Contamination of the hair may result from direct contact with explosive particles or from secondary contact by hand. Also the paper demonstrates that hair can concentrate explosive from the ambient vapour of a variety of military explosives. It was found that the amount of TNT picked up by the hair increased with time of vapour exposure. The data also suggested that unwashed hair may pick up more TNT than washed hair.

Air Pollutants↗

PubMed2001

Degradation of explosives by nitrate ester reductases.

Explosive-contaminated land poses a hazard both to the environment and to human health. Microbial enzymes, either in their native or heterologous hosts, are a powerful and low-cost tool for eliminating this environmental hazard. As many explosives have only been present in the environment for 10 years, and with similar molecules not known in Nature, the origin of enzymes specialized for the breakdown of explosives is of particular interest. Screening of environmental isolates resulted in the discovery of flavoproteins capable of denitrating the explosives pentaerythritol tetranitrate (PETN) and glycerol trinitrate. These nitrate ester reductases are related in sequence and structure to Old Yellow Enzyme from Saccharomyces carlsbergenisis. All the members of this family have alpha/beta barrel structures and FMN as a prosthetic group, and reduce various electrophilic substrates. The nitrate ester reductases are, however, unusual in that they display activity towards the highly recalcitrant, aromatic explosive 2,4,6-trinitrotoluene, via a reductive pathway resulting in nitrogen liberation. We have embarked on a detailed study of the structure and mechanism of PETN reductase from a strain of Enterobacter cloacae. Work is focused currently on relating structure and function within this growing family of enzymes, with a view to engineering novel enzymes exhibiting useful characteristics.

Biodegradation, Environmental↗

PubMed1980

Burns due to grain dust explosions.

Dust explosions occurring in grain elevator storage and processing operations are increasing in frequency and are a world-wide source of injury and fatality. Despite extensive investigation by both private and governmental interests, the causes of most grain dust explosions remain a mystery. A number of methods to help prevent such explosions have been developed, but none has gained uniform acceptance. Despite a brief contact with flame in the flash of a dust cloud ignition, temperatures may exceed 1,000 degrees F and can cause severe burns. A single burn center's experience with eight patients injured in three separate grain elevator dust explosions during a 12-month period highlights the potential seriousness of the problem. Physicians practicing in grain producing or shipping areas of the world should be aware of the potential hazard imposed by grain storage operations. Prevention of these explosions by mandatory dust control systems and appropriate safety regulations is emphasized.

Adolescent↗

PubMed1996

Blast injuries: bus versus open-air bombings--a comparative study of injuries in survivors of open-air versus confined-space explosions.

OBJECTIVES: To compare injury patterns resulting from explosions in the open air versus within confined spaces. METHODS: Medical charts of 297 victims of four bombing events were analyzed. Two explosions occurred in the open air and two inside buses. Similar explosive devices were applied in all four incidents. The incidence of primary blast injuries, significant penetrating trauma (Abbreviated Injury Scale score > or = 2), burns, Injury Severity Score, Revised Trauma Score, and mortality were compared between the two populations. RESULTS: A total of 204 casualties were involved in open-air bombings, 15 of whom died (7.8%). Ninety-three victims were involved in bus bombings, 46 of whom died (49%). The difference in mortality rate was highly significant, p < 0.00001. Primary blast injuries were observed in 25 and 31 victims (34.2% and 77.5% of admitted victims), respectively (p = 0.00003). Median Injury Severity Score was 4 versus 18, respectively (p < 0.0001). CONCLUSION: Explosions in confined spaces are associated with a higher incidence of primary blast injuries, with more severe injuries and with a higher mortality rate in comparison with explosions in the open air.

Adolescent↗

PubMed2002

Pacemaker explosions in crematoria: problems and possible solutions.

The number of artificial cardiac pacemakers is increasing, as is the number of bodies being cremated. Because of the explosive potential of pacemakers when heated, a statutory question on the cremation form asks whether the deceased has a pacemaker and if so whether it has been removed. We sent a questionnaire to all the crematoria in the UK enquiring about the frequency, consequences and prevention of pacemaker explosions. We found that about half of all crematoria in the UK experience pacemaker explosions, that pacemaker explosions may cause structural damage and injury and that most crematoria staff are unaware of the explosive potential of implantable cardiac defibrillators. Crematoria staff rely on the accurate completion of cremation forms, and doctors who sign cremation forms have a legal obligation to provide such information.

Explosions↗

PubMed2003

Trace explosive detection in aqueous samples by solid-phase extraction ion mobility spectrometry (SPE-IMS).

Law enforcement agencies use ion mobility spectrometers for the detection of explosives, drugs of abuse, and chemical warfare agents. Ion mobility spectrometry (IMS) has the advantages of short analysis times, detections in the parts per billion concentrations, and high sensitivity. On-site environmental analysis of explosives or explosive residues in water is possible with ion mobility spectrometers. Unfortunately, the direct analysis of low levels of explosives in water is difficult. Extraction provides a method for pre-concentrating the analytes and removing interferents. Coupling solid-phase extraction (SPE) with IMS is useful for the identification of trace amounts of explosives in water. Commercially available SPE disks were used. After extraction, the sample disk is inserted into the ion mobility spectrometer, where the analytes are thermally desorbed from the disk. Concentrations as low as one part per trillion were detected with a Barringer Ionscan 350. An external computer and acquisition software (LabVIEW, National Instruments) were used to collect data. SIMPLISMA (SIMPLe-to-use-Interactive Self-modeling Mixture Analysis) was applied to the data to resolve features that vary with respect to time.

Aniline Compounds↗

PubMed1991

[Explosion accidents during work with tires and wheel rims].

The object of this work is to draw attention to injuries resulting from explosions caused by work with wheel rims and tyres, the extent of the problem and the safety rules which already exist. Seven illustrative cases are presented. A not inconsiderable but frequently disregarded risk for accidental explosions is present in connection with pumping tyres and repairs of tyres and wheel rims. During the explosions, pressure waves of enormous violence may frequently be released. In connection with four accidental explosions of this type, a total of seven persons were injured. Four of these sustained life-threatening injuries. On the basis of the serious accidents, the authors consider it important to draw attention to the fact that the rules, which exist already and which are aimed primarily at avoiding and possibly limiting the extent of the violent explosive energy, should be brought to the notice of all who work with tyres and wheel rims.

Accidents, Occupational↗

PubMed2004

Muscle-fiber conduction velocity estimated from surface EMG signals during explosive dynamic contractions.

Muscle-fiber conduction velocity (CV) was estimated from surface electromyographic (EMG) signals during isometric contractions and during short (150-200 ms), explosive, dynamic exercises. Surface EMG signals were recorded with four linear adhesive arrays from the vastus lateralis and medialis muscles of 12 healthy subjects. Isometric contractions were at linearly increasing force from 0% to 100% of the maximum. The dynamic contractions consisted of explosive efforts of the lower limb on a sledge ergometer. For the explosive contractions, muscle-fiber CV was estimated in seven time-windows located along the ascending time interval of the force. There was a significant correlation between CV values during the isometric ramp and explosive contractions (R = 0.75). Moreover, CV estimates increased significantly from (mean +/- SD) 4.32 +/- 0.46 m/s to 4.97 +/- 0.45 m/s during the increasing-force explosive task. It was concluded that CV can be estimated reliably during dynamic tasks involving fast limb movements and that, in these contractions, it may provide important information on motor-unit control properties.

Adult↗

PubMed2003

Non-aerosol detection of explosives with a continuous flow immunosensor.

Contamination of groundwater, soil, and the marine environment by explosives is a global issue. Identification, characterization and remediation are all required for a site recognized as contaminated with 2,4,6-trinitrotoluene (TNT) or hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). For each step, a method to accurately measure the contaminant level is needed. This paper reviews some of the current methods with emphasis on a single biosensor developed in our laboratory. Current regulatory methods require samples to be sent off-site to a certified laboratory resulting in time delays up to a month. A continuous flow biosensor for detection of explosives has been developed and tested for the rapid field screening of environmental samples. The detection system is based on a displacement immunoassay in which monoclonal antibodies to (TNT) and RDX are immobilized on solid substrates, allowed to bind fluorescently labeled antigens, and then exposed to explosives in aqueous samples. Explosive compounds present in the sample displace proportional amounts of the fluorescent label, which can then be measured to determine the original TNT or RDX concentration. The system can accurately detect ppb to ppt levels of explosives in groundwater or seawater samples and in extracts of contaminated soil. The biosensor has applications in environmental monitoring at remediation sites or in the location of underwater unexploded ordnance.

Aerosols↗

PubMed2005

Time-frequency analysis and estimation of muscle fiber conduction velocity from surface EMG signals during explosive dynamic contractions.

Time-frequency analysis of the surface electromyographic (EMG) signal is used to assess muscle fiber membrane properties during dynamic contractions. The aim of this study was to compare the direct estimation of average muscle fiber conduction velocity (CV) with instantaneous mean frequency (iMNF) of surface EMG signals in isometric and explosive dynamic contractions. The muscles investigated were the vastus lateralis and medialis of both thighs in 12 male subjects. The isometric contractions were at linearly increasing force (0-100% of the maximal voluntary contraction in 10s). The explosive contractions were performed on a multipurpose ergometer-dynamometer (MED). The subject, sitting on the MED, performed six explosive contractions, separated by 2 min rest, by pushing against two force platforms and thrusting himself backwards with the maximum possible speed, while completely extending his legs. The estimated CV significantly increased with force in both the isometric (mean+/-S.D., from 3.24+/-0.34 to 5.12+/-0.31 m/s for vastus lateralis and from 3.17+/-0.26 to 5.11+/-0.34 m/s for vastus medialis, with force in the range 10-100% of the maximal voluntary contraction level) and explosive contractions (from 4.36+/-0.49 to 5.00+/-0.47 m/s for vastus lateralis, and from 4.32+/-0.46 to 4.94+/-0.44 m/s for vastus medialis, with force in the range 17.5-100% of maximal thrusting force). Moreover, estimated CV was not significantly different at the maximal force in the two exercises. On the contrary, iMNF, computed from the Choi-Williams time-frequency transform, was significantly lower in the explosive (57.7+/-8.2 and 66.5+/-10.3 Hz for vastus laterialis and medialis, respectively) than in the isometric exercises (73.7+/-9.2 and 75.0+/-8.5 Hz for vastus laterialis and medialis, respectively) and did not change with force in any of the conditions. It was concluded that EMG spectral features provide different information with respect to average muscle fiber CV in dynamic contractions. Thus, in general, they cannot be used to infer CV changes during the exertion of a dynamic task. A joint analysis of CV and EMG spectral features is necessary in this type of contractions.

Adult↗

PubMed2002

Dissolution rates of three high explosive compounds: TNT, RDX, and HMX.

Incidental exposure to high explosive compounds can cause subtle health effects to which a population could be more susceptible than injury by detonation. Proper source characterization is a key requirement in the conduct of risk assessments. For nonvolatile solid explosives, dissolution is one of the primary mechanisms that controls fate and transport, resulting in exposure to these compounds remote from their source. To date, information describing dissolution rates of high explosives has been sparse. The objective of this study was to determine the dissolution rates of three high explosive compounds, 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), in dilute aqueous solutions as a function of temperature, surface area, and energy input. To determine each variable's impact on dissolution rate, experiments were performed where one variable was changed while the other two were held constant. TNT demonstrated the fastest dissolution rate followed by HMX and then RDX. Dissolution rate correlation equations were developed for each explosive compound incorporating the three aforementioned variables, independently, and collectively in one correlation equation.

Azocines↗

PubMed2001

Existence of phase explosion during laser ablation and its effects on inductively coupled plasma-mass spectroscopy.

A sudden increase in crater depth was observed during high irradiance (> 10(10) W/cm2) laser ablation of silicon, and it is attributed to the phenomenon of phase explosion. The threshold irradiance for phase explosion showed a dependence on two laser parameters: laser beam spot size and wavelength. For a larger beam size and longer incident wavelength, a higher laser irradiance was required to generate phase explosion. The rapid increase of crater depth above the phase explosion threshold irradiance correlated with a significant increase in the ICPMS signal intensity. The ratio of crater volume to ICPMS intensity, which represents entrainment efficiency, remained the lowest at laser irradiances slightly above the phase explosion threshold. However, this ratio increased at irradiances well above the threshold (> 10(11) W/cm2). Chemical analysis using laser ablation at irradiance above 10(11) W/cm2 provides increased sensitivity via improved entrainment and transport efficiency and increased ablation rate.

Journal Article↗