Results 1 - 10 of 344
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[en] Green Field II (GFII) project conducted in Israel during 2010-11 aimed at increasing the preparedness for possible terrorism events, where a radioactive material coupled to an explosive charge might be dispersed. The project included seven tests where ∼6Ci of 99mTc was dispersed by 0.25-2.5 kg TNT charges. The dispersion was done above clean or dirt surfaces, from the ground level or 1m above it. Comparison between the different situations will be shown as well as new parameterizations suggested to being included within the existing models. The paper will describe the project objectives, the experimental setups, some of the results obtained in these experiments and preliminary analysis of these results
[en] We present a study into three generations of fluorescent carbazole-based dendrimers that exhibit strong binding with nitroaromatic compounds accompanied by photoluminescence (PL) quenching, making them attractive sensing materials for the detection of explosives such as 2,4,6-trinitrotoluene (TNT). The absorption and release of the (deuterated) TNT analogue, 4-nitrotoluene (pNT), from thin films of the dendrimers were studied with a combination of time-correlated neutron reflectometry and PL spectroscopy. When saturated with pNT the PL of the films was quenched and could only be recovered with a nitrogen gas flow upon heating to 40-80°C. Although the majority of the absorbed pNT was removed by this method the neutron reflectometry showed that the recovered films still contained residual quantities of pNT. However, the proportion of the PL recovered increased strongly with generation with the third generation dendrimer exhibiting full recovery. This result is attributed to a combination of two effects. Firstly, the dendrimer films present a range of binding sites for nitroaromatic molecules, with molecules bound to the higher energy sites remaining after the thermal recovery. Secondly, the exciton diffusion coefficient decreases with dendrimer generation, inhibiting the PL quenching by the bound pNT.
[en] The principal task of our studies is to provide a rational interpretation of the thermodynamic and fluid dynamic events taking place in a closed vessel upon detonation of an explosive charge and subsequent turbulent combustion of its products, acting as fuel for an exothermic reaction with air. Under such circumstances, the latter has been compressed by a reverberating shock front of the blast wave generated by the explosion. The paper presents the chemical and thermodynamic background and its numerical results, deduced for this purpose from mass spectroscopic data and pressure records, acquired upon explosion of a 0.8 kg charge of TNT in a 17 m3 chamber filled with air--a diagnostic analysis identified by the title. The evolution of the flow field and its structure are presented in a companion paper
[en] The environmental impact caused by the production of explosives made from nitroaromatic compounds such as 2,4,6-trinitrotoluene (TNT) is currently a major concern, mainly due to their toxic nature, a fact that makes these compounds highly harmful. This work evaluated a continual system treatment reactor (CSTR) consisting of column zero-valent iron and a system to promote a fenton reaction in order to create possible definitive routines for treating effluents originating from the TNT production process. The spectrophotometric results demonstrated that this combination of processes was highly efficient in promoting the removal of all the absorbed species at 290 nm and the visible region of the specter. The results also revealed that the combination of treatments was significantly efficient in terms of correcting the effluent's main parameters of relevance, mainly COD (95.5% reduction) and TNT concentration, whose total was converted into nitrous and phenolic compounds and, additionally, the acute toxicity was also significantly reduced (95%). These results indicate that the strategy can serve as an efficient option for effluent treatment, for release into the receiving body, or eventually for use as industrial reuse water.
[en] The blast-wave flows both outside and inside a power house of a nuclear-power generating station, from an accidental explosion of an explosive like TNT or its equivalent during transportation past the power house by a train, are studied numerically and assessed with an appropriate model. Detailed descriptions of both the prediction model and numerical method of solution are given, as well as an interpretation of numerical results. The blast-wave flow into the power house through blow-out panels in the front wall is investigated, including the resulting flow inside the power house that travels through the turbine hall, through the turbine auxiliary bay, over the reactivity deck, through the reactor building, and, in some cases, down through a hoistway to three small rooms on the next lower level. Breaking blow-out panels in the rear wall of the power house and their effects on the internal blast-wave flow is also investigated. Two different flow paths are considered, one through an upper level of the power house and another through a lower level. Finally, the blast-wave flow over the outside of the power house is studied, with an approximate model, so that the pressure differences from the blast wave between the inside and outside of the roof, side walls, front wall, and rear wall can be determined and the resultant blast-wave loading on the building walls thereby obtained
[en] The following two metabolites of TNT were prepared: 2,4-dinitro-6-aminotoluene and 2,4-dinitro-4-aminotoluene. The first was prepared by ''cold'' microsynthesis and not by ''hot'' one because of technical problems. The second was synthesized by a ''hot'' synthesis as well. The resulting specific activity was 4.26 Ci/mmol. (Author)
[en] A scanner system, operating in a non-destructive and non-invasive way, is presented for pipeline inspection to determine its location in land soil, wall thickness, type of liquid flowing and crack/ blockage position. In the present experiment, incoherent scattered intensity of NaI(Tl) scintillation detector provides the desired information. The method is quite sensitive for small change (∼ 1 mm) in the thickness of pipe wall, locating defect of 1 mm width under insulation and small change (∼ 0.1 gm-cm-3) in the density of liquid flowing through pipe. The use of the scanner system for detection of explosives (landmines) such as TNT (C7H5N3O6) and RDX (C3H6N6O6) will be described. These explosive materials have a density less than that of metals and different from various types of soils. The explosive simulant phantom is buried at depth of ∼ 2 cm in soil, so the photons have to penetrate this much distance before interacting with buried material. The scattered intensity originating from interactions of photons with the phantom has the potential to detect the presence of landmine. (author)
[en] A novel molecularly imprinted polymer (MIP) was synthesized as a highly selective and specific sorbent for solid phase extraction (SPE) of 2,4,6-trinitrotoluene (TNT). TNT-MIP was prepared by bulk polymerisation process using 2,4,6-trinitrotoluene (TNT) as template, methacrylic acid (MAA) as the functional monomer and ethylene glycol dimethylacrylate (EGDMA) as the cross-linker. Non-imprinted polymer (NIP) was prepared under the similar procedure but without the addition of template as a control polymer. Prior to analysis, the polymer monoliths were ground and sieved in the range of 25-38 μm before incorporated as SPE sorbent. The TNT-MIP and NIP performance validation were analysed by high performance liquid chromatography (HPLC) at 254 nm of UV detector. The limit of detection (LOD) and limit of quantitation (LOQ) range were 0.03-0.07 μg/mL and 0.05-0.11 μg/mL, respectively. The MIP showed excellent selectivity towards the template, TNT with percentage recovery and RSD value, 94.1±13.7 compared to TNTs metabolites, 4-amino-2,6-dinitrotoluene, 4-ADNT (31.7±27.2) and 2-amino-4,6-dinitrotoluene, 2-ADNT (41.2±6.1), respectively. The physical imprinting effect of MIP and NIP was characterized by using scanning electron microscopy (SEM) and Brunauer, Emmett and Teller (BET). Evaluation performance proved that the developed TNT-MIP was good in TNT selectivity and could be applied in real samples analysis. (author)
[en] Using a mini muon tracker developed at the Los Alamos National Laboratory we performed experiments of simple landscapes of various materials, including TNT, 9501, lead, tungsten, aluminium, and water. Most common scenes are four two inches thick step wedges of different dimensions: 12-inch x 12-inch, 12-inch x 9-inch, 12-inch x 6-inch, and 12-inch x 3-inch; and a one three inches thick hemisphere of lead with spherical hollow, and a similar full lead sphere.