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Estimation of the critical rate of temperature rise for thermal explosion of first-order autocatalytic decomposition reaction systems using non-isothermal DSC.

A method of estimating the critical rate of temperature rise for thermal explosion of first-order autocatalytic decomposition reaction systems using non-isothermal DSC is presented. Information is obtained on the increasing rate of temperature in highly nitrated nitrocellulose containing 14.14% of nitrogen when the first-order autocatalytic decomposition converts into thermal explosion.

Catalysis↗

Experimental evaluation of LPG tank explosion hazards.

Liquefied-pressure gases (LPG) are transported and stored in the liquid phase in closed tanks under sufficiently high pressure. In the case of an accident, an abrupt tank unsealing may release enormous quantity of evaporating gas and energy that has a destructive effect on the tank and its surroundings. In this paper, experiments with explosions of small LPG tanks are described. The data acquisition equipment applied in the tests provided a chance to learn dynamics of the process and determine hazard factors. The tests enabled a determination of temperature and pressure at which tanks containing LPG disrupt. The results enable a reconstruction of consecutive phases of the explosion and identification of hazards resulting from damage of the tanks. An explanation of the tank unsealing process with fluid parameters above critical point is given.

Accidents, Occupational↗

Cost-effective synthesis of 5,7-diamino-4,6-dinitrobenzofuroxan (CL-14) and its evaluation in plastic bonded explosives.

5,7-Diamino-4,6-dinitrobenzofuroxan (CL-14) has been synthesized by a cost-effective method. CL-14 was characterized by spectral data (IR, NMR and mass) and elemental analysis. The compound was evaluated in plastic bonded explosives (PBX) using polyurethane (PU) as binder. The thermal, mechanical and explosive properties of PBX composition from preliminary tests are also reported. Good thermal stability as well as good insensitiveness are indicated.

Cost-Benefit Analysis↗

Comparison of two standard test methods for determining explosion limits of gases at atmospheric conditions.

A comparison is made between two internationally accepted methods to determine the explosion limits of gases at atmospheric pressure and room temperature (20 l sphere - DIN 51649). Significant differences (about 1 vol.%) in the upper explosion limits (UEL) values are found for four hydrocarbons tested. A new criterion is proposed which leads to close agreement between the UEL values obtained by the two methods.

Atmospheric Pressure↗

Burns due to aerosol can explosions.

This report describes one burn service's experience with burn injuries sustained by 18 patients over a 5-year period as a result of the explosion of pressurized aerosol cans. The burns were predominantly superficial flash burns and involved from 5 to 45 per cent of the body surface area. There were no deaths in the series. Heightened public awareness of the fire and explosive hazards of these cans, as well as a more prominent warning label on the can should aid in decreasing the incidence of these injuries.

Adolescent↗

Explosive burns during abusive inhalation of butane gas.

Explosion burns during abusive inhalation of butane gas rarely occurred in the past, but recently it has become a social problem among groups of teenagers. This cause constitutes 1.6% of admissions due to flame burn at the burn unit of Hallym Medical Center. A retrospective review during a five-year period identified 48 patients. The male to female ratio was 3:1. The mean age of patients was 16 years and 8 months. The places where the accidents occurred were commonly bedrooms or motel rooms. There were nine group settings of 27 patients at the time of the accident. Inhalation injury (n = 12) was noted on admission. The average burn size was 28.5 percent of the total body surface area. All patients sustained burn injury on the face, arms and hands and 24 patients among them had extended burn areas on the trunk and/or lower extremity. 22 patients (mean hospital stay; 51.6 d) required skin grafting and 12 patients (mean hospital stay; 22.3 d) were treated with conservative management. The mortality rate was 10.4 percent. Explosion burns during abusive inhalation of butane gas can result in mortality as well as major burn injuries.

Accidents↗

Analysis of nitroaromatic compounds in urine by gas chromatography-mass spectrometry for the biological monitoring of explosives.

Organic nitrocompounds are the most frequently used constituents of explosives and some of them have been evaluated to be highly toxic or even carcinogenic. Human contact with explosives may originate from a variety of sources, including occupational exposure during the production of ammunition as well as environmental exposure due to the contamination of soil and ground water reservoirs on former military production sites and training areas. This paper describes two gas chromatography-mass spectrometry-selected ion monitoring methods for the determination of twelve nitroaromatic compounds in urine (nitrobenzene, 1,2-dinitrobenzene, 1,3-dinitrobenzene, 1,3,5-trinitrobenzene, 2-nitrotoluene, 3-nitrotoluene, 4-nitrotoluene, 2,4-dinitrotoluene, 2,6-dinitrotoluene, 2,4,6-trinitrotoluene, 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene). The analytes are detectable in the lowest microg/l range, with imprecisions of 3-22% within series and 5-29% between series, depending on the compound of interest. Both procedures are rapid and relatively easy to perform and, therefore, are advantageous for the screening of occupationally or environmentally exposed persons. We analysed urine samples obtained from nine workers from an ammunition dismantling workshop and from twelve control persons. 2,4,6-Trinitrotoluene was detected in six samples at concentrations between 4 and 43 microg/l. The main metabolites of 2,4,6-trinitrotoluene, 4-amino-2,6-dinitrotoluene and 2-amino-4,6-dinitrotoluene, were found in a concentration range from 143 to 16,832 microg/l and from 24 to 5787 microg/l, respectively. Nonconjugated aminodinitrotoluenes were present as varying percentages of the total amount. 2,4-Dinitrotoluene and 2,6-dinitrotoluene were found in two samples (2-9 microg/l). Nitroaromatics were not detectable in urine specimens from control persons.

Aniline Compounds↗

Novel electrolyte for the analysis of cations in low explosive residue by capillary electrophoresis.

A novel electrolyte has been developed for the effective separation by capillary electrophoresis of cations detected in low explosive residue. This electrolyte, with a pH of 4.4, employs 17.5 mM alpha-hydroxyisobutyric acid (HIBA) as the complexing agent, 6 mM imidazole as the ultraviolet visualization agent, 4 mM 18-crown-6 ether as a modifier to enhance the selectivity of the inorganic cations, and 5% (v/v) acetonitrile as an organic additive. Studies which assessed the value of the addition of 18-crown-6 and acetonitrile demonstrated conclusively that both were required in order to achieve unambiguous baseline separation of ammonium, potassium and monomethylammonium ions. The major advantages of the use of this electrolyte are a total run time of less than 7 min and symmetrical peak shapes. Validation on a series of preblast and postblast explosives materials determined that this procedure is reliable and robust.

Acetonitriles↗

[Intestinal gas explosion during operation: a case report].

A case of intestinal gas explosion during the course of carcinologic surgery in a 51-year-old patient is reported. This accident, often dramatic, has become exceptional since the use of mannitol for colonic preparation has disappeared. This incident occurred during the course of a total pelvic exenteration performed under general anaesthesia with inhalation of both a mixture oxygen-nitrous oxide and volatile agents. The colon incision with an electrocautery was contemporaneous with a violent deflagration accountable for organic lesions. This case report reminds us that the risk of a dangerous explosion persists in relation with surgical, anaesthetic and individual risk factors.

Adenocarcinoma↗

Direct imaging of explosives.

Any technique that can detect nitrogen concentrations can screen for concealed explosives. However, such a technique would have to be insensitive to metal, both encasing and incidental. If images of the nitrogen concentrations could be captured, then, since form follows function, a robust screening technology could be developed. However these images would have to be sensitive to the surface densities at or below that of the nitrogen contained in buried anti-personnel mines or of the SEMTEX that brought down Pan Am 103, approximately 200 g. Although the ability to image in three-dimensions would somewhat reduce false positives, capturing collateral images of carbon and oxygen would virtually assure that nitrogenous non-explosive material like fertilizer, Melmac dinnerware, and salami could be eliminated. We are developing such an instrument, the Nitrogen Camera, which has met experimentally these criteria with the exception of providing oxygen images, which awaits the availability of a sufficiently energetic light source. Our Nitrogen Camera technique uses an electron accelerator to produce photonuclear reactions whose unique decays it registers. Clearly if our Nitrogen Camera is made mobile, it could be effective in detecting buried mines, either in an active battlefield situation or in the clearing of abandoned military munitions. Combat operations require that a swathe the width of an armored vehicle, 5 miles deep, be screened in an hour, which is within our camera's scanning speed. Detecting abandoned munitions is technically easier as it is free from the onerous speed requirement. We describe here our Nitrogen Camera and show its 180 pixel intensity images of elemental nitrogen in a 200 g mine simulant and in a 125 g stick of SEMTEX. We also report on our progress in creating a lorry transportable 70 MeV electron racetrack microtron, the principal enabling technology that will allow our Nitrogen Camera to be deployed in the field.

Explosions↗

An overview of the scientific examinations performed after an explosion on the Shankill Road.

In October 1993 an explosion occurred in a busy fish shop on the Shankill Road in Belfast resulting in the deaths of ten people and multiple casualties. Examinations were carried out by forensic scientists at the scene and in the laboratory to determine the cause of the explosion and to establish evidence of contact between the suspects and the incident.

Automobiles↗

Novel technique for the combined recovery, extraction and clean-up of forensic organic and inorganic trace explosives samples.

This paper describes a simple processing and analysis scheme for explosives trace swab samples which deals both with organic and inorganic materials. Swabs, wetted with ethanol or ethanol/water mixture, were extracted with ethanol/water mixture. The extract was passed directly through a simple column containing an acrylonitrile/styrene copolymer adsorbent. The adsorbent retained common organic explosives, which were recovered with an efficiency of 30-50% as a relatively clean ethyl acetate solution. The concentrated ethyl acetate eluate was analysed using gas chromatography with chemiluminescence or mass spectrometric detection. The unretained inorganic ions and sugars, which were recovered with generally high efficiency as an ethanol/water solution, could be directly analysed using ion chromatography and/or capillary electrophoresis. Minor difficulties encountered in the analysis of sugars, fluoride and phosphate were examined.

Chromatography, Gas↗

AOTF Raman spectrometer for remote detection of explosives.

A spectrometer based on acousto-optic tunable filters is developed for use in measuring Raman spectra as part of a detection system that is low-cost, reliable, and field-portable. The system is coupled with a fiber optic bundle to carry the excitation laser light to the sample and to collect the Raman scattered light. Spectra of the explosives trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX) and nitroguanidine (NQ) were obtained in very short times and are in good agreement with those taken with conventional Fourier transform Raman spectrometers. Spectra of mixtures of explosives were also obtained and show no overlap of their characteristic Raman bands.

Azocines↗

An explosive-degrading cytochrome P450 activity and its targeted application for the phytoremediation of RDX.

The widespread presence in the environment of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), one of the most widely used military explosives, has raised concern owing to its toxicity and recalcitrance to degradation. To investigate the potential of plants to remove RDX from contaminated soil and water, we engineered Arabidopsis thaliana to express a bacterial gene xplA encoding an RDX-degrading cytochrome P450 (ref. 1). We demonstrate that the P450 domain of XplA is fused to a flavodoxin redox partner and catalyzes the degradation of RDX in the absence of oxygen. Transgenic A. thaliana expressing xplA removed and detoxified RDX from liquid media. As a model system for RDX phytoremediation, A. thaliana expressing xplA was grown in RDX-contaminated soil and found to be resistant to RDX phytotoxicity, producing shoot and root biomasses greater than those of wild-type plants. Our work suggests that expression of xplA in landscape plants may provide a suitable remediation strategy for sites contaminated by this class of explosives.

Arabidopsis↗

A field test for the detection of peroxide-based explosives.

A rapid and simple field test for the detection of triacetone-triperoxide (TATP) and hexamethylenetriperoxidediamine (HMTD), two explosives which find significant illegal use, has been developed. Unknown samples are first treated with a catalase solution to remove hydrogen peroxide traces, in order to provide selectivity towards peroxide-based bleaching agents which are contained in commercial laundry detergents. Subsequently, the peroxide-based explosives are decomposed via UV irradiation, thus yielding hydrogen peroxide, which is determined by the horseradish peroxidase (POD) catalysed formation of the green radical cation of 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS). The limits of detection for this method are 8 x 10(-6) mol dm(-3) for TATP and 8 x 10(-7) mol dm(-3) for HMTD, respectively. As an option, p-hydroxyphenylacetic acid (pHPAA) may be used as peroxidase substrate, resulting in lower limits of detection (8 x 10(-7) mol dm(-3) for TATP and HMTD). The complete method uses a mobile setup to be applied under field conditions.

Explosions↗

A brief historical review of non-anaesthetic causes of fires and explosions in the operating room.

Fires and explosions have occurred in the operating theatre for many years. Flammable inhalation anaesthetic agents were responsible for many incidents in the past, but these are no longer available in many countries. Other causes of fires and explosions still exist in the operating theatre and, from time to time, result in serious and occasionally fatal injury. Flammable gastrointestinal gases have been the cause of injury to patients during gastric surgery, laparoscopy and during examination of the large bowel with electrical instrumentation. Gases formed in the bladder during urological procedures have ignited, causing rupture. Alcohol-based skin cleaning agents have resulted in severe burns to the skin. Equipment used for storage and delivery of oxygen to patients has caused fires in a variety of ways. Adhesive skin drapes have resulted recently in two tragic deaths. The increasing use of laser therapy, particularly in ear, nose and throat surgery, and in oral surgery, has brought about a renewed awareness of the risk of fire. The relevant factors which should be borne in mind and the precautions which should be adopted when laser therapy is to be used in the airway are discussed.

Catheterization↗

Death due to a methane gas explosion in a tunnel on urban reclaimed land.

Studies of four male victims who were killed in an accidental tunnel gas explosion on urban reclaimed land are described. The studies were judicial autopsy examinations to determine the precise causes of death. Two men died of carbon monoxide intoxication, one died of massive brain damage, and the fourth died of drowning. The concentrations of methane in several organs were much lower than the lethal level, whereas those in adipose tissue were relatively high. These findings indicated that a low concentration of methane was almost always present in the atmosphere at the construction site. Recently, coal mine accidents have been decreasing in Japan. However, there is still a possibility of underground explosions or gas leaks in confined spaces other than coal mines. To determine the precise cause of death in such cases, careful autopsies and other examinations should be performed using methods similar to those used in coal mine accidents.

Adult↗

Fatal carbon monoxide poisoning after the detonation of explosives in an underground mine: a case report.

An unusual death caused by carbon monoxide poisoning after the detonation of explosives in an underground mine was investigated by the Office of the Medical Investigator of the State of New Mexico. The 50-year-old miner had 18 years of mining experience but no documented safety training. He collapsed approximately 20 minutes after entering the mine and working at the bottom of the single vertical shaft. The tight confines of the mine shaft hindered rescue personnel from reaching him, and the body was not recovered until 2 days later. The autopsy showed severe coronary artery atherosclerosis with remote and resolving myocardial microinfarcts, as well as the characteristic pink lividity of carbon monoxide poisoning, which was confirmed by laboratory analysis. Detailed investigation of the scene revealed no sources of carbon monoxide other than the explosives. The case represents an uncommon cause of death in mining that may have been avoided through the use of proper safety procedures, and illustrates the importance of recognizing the many sources of carbon monoxide.

Carbon Monoxide Poisoning↗