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PubMed2006

Prediction of shock sensitivity of explosives based on small-scale gap test.

A new method is described to predict shock sensitivity of C(a)H(b)N(c)O(d) explosives without using any experimental data. It can determine shock sensitivity based on small-scale gap test as the pressure required to initiate material pressed to 90%, 95% and 98% of theoretical maximum density. Three essential parameters would be needed in the new scheme which contain a+b/2-d, the existence of alpha-C-H linkage in nitroaromatic compounds or NNO(2) functional group and difference of the number of amino and nitro groups attached to aromatic ring. Predicted shock sensitivities in some well-known explosives have a root mean square (rms) deviation of 3.97, 4.02 and 5.89kbar of experiment to initiate pressure of material pressed to 90%, 95% and 98% of theoretical maximum density, respectively.

Explosions↗
PubMed2006

New method for calculating densities of nitroaromatic explosive compounds.

A new model has been introduced for simple calculation of crystal density of an important class of organic explosives, namely nitroaromatic energetic compounds. This model is based on the fundamental correlation. The introduced procedure has been applied to 60 well-known and new synthesized organic nitroaromatic explosives. The results show that the present method gives comparable prediction respect to well-developed group additivity method for estimation of crystal density of organic explosives. The introduced simple method can be applied to any complex nitroaromatic explosive that contains the elements of carbon, hydrogen, nitrogen and oxygen with no difficulties.

Crystallization↗
PubMed2006

The neurological consequences of explosives.

Neurological injuries produced by explosive blasts are the result of a cascade of events that begin with the initial explosion and evolve from the secondary, tertiary, and quaternary effects that the explosion engenders [Lavonis EJ. Blast Injuries. EMedicine.htm]. Only the results of the primary blast are predictable, and subsequent actions ripple outward in an increasingly random and chance sequence. This article reviews and explains how the ensuing chain of circumstances injures the nervous system, and what examining physicians should anticipate when they treat these patients.

Brain Injuries↗
PubMed2006

A TaqMan polymerase chain reaction method for monitoring RDX-degrading bacteria based on the xplA functional gene.

Hexahydro-1,3,5-trinitro-1,3,5,-triazine (RDX) is a cyclic nitramine explosive that is a major component in many military high-explosive formulations. In this study, we developed a real-time TaqMan polymerase chain reaction (PCR) that targets the xplA functional gene involved in the breakdown/transformation of RDX. The xplA gene, described previously [Seth-Smith, H.M., Rosser, S.J., Basran, A., Travis, E.R., Dabbs, E.R., Nicklin S., Bruce, N.C., 2002. Cloning, sequencing, and characterization of the hexahydro-1,3,5-trinitro-1,3,5-triazine degradation gene cluster from Rhodococcus rhodochrous. Appl. Environ. Microbiol. 68, 4764-4771.], was isolated from Rhodococcus rhodochrous 11Y and codes for a fused flavodoxin-cytochrome P450 protein. We applied the xplA TaqMan PCR assay to detect and monitor strain 11Y in soil microcosms that had been amended with strain 11Y and RDX as well as soil microcosms in which soils had been subjected to heat-sterilization prior to the addition of strain 11Y and RDX. The specificity of the assay was tested against a number of genomic bacterial templates and surprisingly found to cross react with other RDX degrading bacteria. Two of these strains, Gordonia sp. KTR9 and Williamsia sp. KTR4, were previously isolated in our laboratory and were not known to possess xplA homologs. Southern blot analysis confirmed the presence of xplA gene homologs in both of these strains. The sensitivity of the xplA TaqMan PCR primer/probes set was evaluated using 11Y cell standards as well as 11Y cell standards spiked in soils that mimicked conditions found in the experimental soil microcosms. While the assay was found to be linear over a range of 6 orders of magnitude for both sets of standards, sensitivity of the assay was reduced between one and two logs for cells spiked in soil. The capacity to monitor the presence of specific microorganisms and/or genes coding enzymes involved in RDX transformation/breakdown in complex environmental samples will be critical for bioremediation strategies targeting explosives that rely on in situ bioaugmentation and monitored natural attenuation.

Biodegradation, Environmental↗
PubMed2006

Absorbance change and static quenching of fluorescence of meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) by trinitrotoluene (TNT).

Meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) interacts with trinitrotoluene (TNT) and forms a 1:1 complex with a new absorbance peak at 422 nm. TNT quenches TPPS emission intensity at 645 and 702 nm when excited at 413 nm. The TPPS-TNT complex is formed in the ground state on the basis of a linear Stern-Volmer plot indicative of static quenching. The association constants determined from absorbance and fluorescence studies are in excellent agreement.

Adsorption↗
PubMed2000

SnifProbe: new method and device for vapor and gas sampling.

SnifProbe is based on the use of 15 mm short pieces of standard 0.53 mm I.D. capillary or porous layer open tubular columns for sampling airborne, headspace, aroma or air pollution samples. A miniaturized frit-bottomed packed vial named MicroSPE was also prepared which served for the sampling of solvent vapors and gases as well as liquid water. The short (15 mm) trapping column is inserted into the SnifProbe easy-insertion-port and the SnifProbe is located or aimed at the sample environment. A miniature pump is operated for pumping 10-60 ml/min of the air sample through the short piece of column to collect the sample. After a few seconds up to a few minutes of pumping, the short column is removed from the SnifProbe with tweezers (or gloved hands) and placed inside a glass vial of a direct sample introduction device (ChromatoProbe) having a 0.5 mm hole at its bottom. The ChromatoProbe sample holder with its glass vial and sample in the short column are introduced into the GC injector as usual. The sample is then quickly and efficiently desorbed from the short sample column and is transferred into the analytical column for conventional GC and/or GC-MS analysis. We have explored the various characteristics of SnifProbe and demonstrated its applicability and effectiveness in many applications. These applications include: the analysis of benzene, toluene and o-xylene in air, SO2 in air, perfume aroma on hand, beer headspace, wine aroma, coffee aroma, cigarette smoke, trace chemical warfare agent simulants, explosives vapors, ethanol in human breath and odorants in domestic cooking gas. SnifProbe can be operated in the field or at a chemical process. The sample columns can be plugged and stored in a small union storage device, placed in a small plastic bag, marked and brought to the laboratory for analysis with the full power of GC and/or GC-MS. Accordingly, we feel that the major and most significant feature of SnifProbe is that it brings the field and process to the laboratory. Thus, SnifProbe can extend the "arm" of the GC and GC-MS laboratory and enable high-quality field and process analysis.

Chromatography, Gas↗
PubMed2006

TNT detection using multiplexed liquid array displacement immunoassays.

The presence of trace contamination of soil and groundwater with explosives is an ongoing concern, for which improved methods are required to facilitate their detection and quantification. This is true both for the monitoring of remediation and for site characterization. Immunosensors have been found effective for solution-phase detection of environmental contaminants. Our work utilized the Luminex100 (flow cytometer) to detect TNT in a multiplexed displacement immunoassay format. The Luminex100 can perform a multiplexed assay by discriminating between up to 100 different bead sets. We used this capability to evaluate four different TNT monoclonal antibodies, two recombinant TNT antibodies, and a control antibody simultaneously for the rapid detection of TNT and other nitroaromatics. TNT could be detected at 0.1 ppb and quantified over the range of 1.0 ppb to 10 ppm. In addition, the assay was shown to be effective in various matrixes such as lake water, seawater, and acetone extracts of soil. Seawater required dilution with two parts buffer to avoid loss of microspheres, while the acetone extracts were diluted 100-fold or more to minimize solvent affects.

Antibodies, Monoclonal↗
PubMed2006

Metallic nanoparticle-carbon nanotube composites for electrochemical determination of explosive nitroaromatic compounds.

Metal nanoparticles (Pt, Au, or Cu) together with multiwalled and single-walled carbon nanotubes (MWCNT and SWCNT) solubilized in Nafion have been used to form nanocomposites for electrochemical detection of trinitrotoluene (TNT) and several other nitroaromatics. Electrochemical and surface characterization by cyclic voltammetry, AFM, TEM, SEM, and Raman spectroscopy confirmed the presence of metal nanoparticles on CNTs. Among various combinations tested, the most synergistic signal effect was observed for the nanocomposite modified glassy carbon electrode (GC) containing Cu nanoparticles and SWCNT solubilized in Nafion. This combination provided the best sensitivity for detecting TNT and other nitroaromatic compounds. Adsorptive stripping voltammetry for TNT resulted in a detection limit of 1 ppb, with linearity up to 3 orders of magnitude. Selectivity toward the number and position of the nitro groups in different nitroaromatics was very reproducible and distinct. Reproducibility of the TNT signal was within 7% (n = 8) from one electrode preparation to another, and the response signal was stable (+/-3.8% at 95% confidence interval) for 40 repeated analyses with 10 min of preconditioning. The Cu-SWCNT-modified GC electrode was demonstrated for analysis of TNT in tap water, river water, and contaminated soil.

Chromatography, Gas↗
PubMed2006

Label-free and reagentless aptamer-based sensors for small molecules.

A label free, reagentless aptasensor for adenosine is developed on an ISFET device. The separation of an aptamer/nucleic acid duplex by adenosine leads to the aptamer/adenosine complex that alters the gate potential of the ISFET. The sensitivity limit of the device is 5 x 10-5 M. Also, the immobilization of the aptamer/nucleic acid duplex on an Au-electrode and the separation of the duplex by adenosine mono-phosphate (AMP) enable the electrochemical detection of adenosine by faradaic impedance spectroscopy. The separation of the aptamer/nucleic acid duplex by adenosine and the formation of the aptamer/adenosine complex results in a decrease in the interfacial electron-transfer resistance in the presence of [Fe(CN)6]3-/4- as redox active substrate.

Adenosine Monophosphate↗
PubMed2006

Solid-state modeling of the terahertz spectrum of the high explosive HMX.

The experimental solid-state terahertz (THz) spectrum (3-120 cm(-1)) of the beta-crystal form of the high explosive octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) has been analyzed using solid-state density functional theory calculations. Various density functionals (both generalized gradient approximation and local density approximation) are compared in terms of their abilities to reproduce the experimentally observed solid-state structure and low-frequency vibrational motions. Good-to-excellent agreement between solid-state theory and experiment can be achieved in the THz region where isolated-molecule calculations fail to reproduce the observed spectral features, demonstrating a clear limitation of using isolated-molecule calculations for the assignment of THz frequency motions in molecular solids. The deficiency of isolated-molecule calculations is traced to modification of the molecular structure in the solid state through crystal packing effects and the formation of weak C-H...O hydrogen bonds.

Azocines↗
PubMed2006

The phenomenon of suicide bombing: a review of psychological and nonpsychological factors.

This article reviews the literature on the phenomenon of suicide bombing. It addresses the question of just how much a psychological understanding of the individuals involved can aid in prevention. The article looks at historical, epidemiological, and cultural perspectives and compares the nonpsychological and psychological approaches to suicide bombing. On the basis of the material available it seems that social processes such as group-dynamic indoctrination and political factors are decisive in analyzing this problem. Cultural, nationalistic, and religious factors are important. The conclusion is that in suicidal bombing, suicide is instrumental in the context of war, not in the context of psychopathology. Suicide bombing is instrumental in realizing fatalities, and it is only one of many weapons. The act of killing in warfare is more important to understanding suicidal terrorism than the act of suicide. This explains why psychological profiling of suicidal terrorists has to date not been successful.

Explosive Agents↗
PubMed2006

Childhood leukaemia and ordnance factories in west Cumbria during the Second World War.

Much evidence has accumulated that childhood leukaemia (CL) is a rare response to a common, but unidentified, infection and in particular that situations involving the unusual mixing of urban and rural groups (approximating to, respectively, groups infected with, and susceptible to, the relevant microorganism) can produce localised epidemics with consequent increases of the infrequent leukaemic complication. During the Second World War, explosives production factories were built and operated at Drigg and Sellafield, and a shell filling factory at Bootle, in west Cumbria, England, requiring substantial numbers of construction workers to be brought into this remote and isolated area. Following the design of an earlier study of CL near large (post-war) rural construction sites, mortality from this disease was investigated with the help of the Office of National Statistics, in the area around these Cumbrian factories where local workers largely lived, during the construction period and with particular reference to the overlapping construction and operational phase when the mixing of local and migrant workers would have been greatest. An excess of leukaemia deaths at ages 1-14 was found during the construction period (observed 3; observed/expected (O/E) 2.2, 95% confidence interval (CI): 0.6, 6.0), which was more marked and statistically significant during the overlap with operations (O 3; O/E 4.5, 95% CI: 1.1, 12.2), especially at ages 1-4 (O 2; O/E 7.1, CI: 1.2, 23.6). A previous investigation did not detect this excess because it considered only a small part of west Cumbria that omitted the communities where most of the workforce lived, having incorrectly attributed the post-war expansion of the village of Seascale (situated between Drigg and Sellafield) to the wartime ordnance factories. The present findings are consistent with the results of the earlier study of rural construction projects and with the general evidence that marked rural-urban population mixing increases the risk of CL.

Adolescent↗
PubMed2006

The development of cryoprobe nuclear magnetic resonance spectroscopy for the rapid detection of organic contaminants in potable water.

The detection of trace levels of a range of organic contaminants (including pesticides, toxins and an explosive) in potable water, using cryoprobe NMR spectroscopy with limited sample preparation and rapid acquisition times, is described. Emphasis is placed on the applicability of NMR spectroscopy for use in emergency scenarios as the unbiased nature of the technique facilitates the detection and characterization of unknown compounds at levels as low as 50 microg L(-1).

Environmental Monitoring↗
PubMed2006

Highly sensitive electrochemical detection of trace liquid peroxide explosives at a Prussian-blue 'artificial-peroxidase' modified electrode.

A highly sensitive electrochemical assay of the peroxide-based explosives triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) at a Prussian-blue (PB) modified electrode is reported. The method involves photochemical degradation of the peroxide explosives and a low potential (0.0 V) electrocatalytic amperometric sensing of the generated hydrogen peroxide at the PB transducer and offers nanomolar detection limits following a short (15 s) irradiation times. The electrochemical sensing protocol should facilitate rapid field screening of peroxide explosives.

Bridged Bicyclo Compounds, Heterocyclic↗