A method for detecting explosives

Bombs concealed in luggage have threatened human life and property throughout the world's traffic. The plastic explosives could not be checked by the X-ray detecting device. A method has been tested in the present work for non-destructive detection of explosives. A neutron generator and relevant apparatus have been used as a tool to find explosives, regardless of the bomb's shape and the packing materials. It seems that this method is a promising one because of the strong transmission ability of both the incident and output specific radiations and low background.     

Adsorption of surfactants on superfine magnetite

Superfine magnetite particles were obtained by chemical condensation. Their size can be varied by the magnetic field application and a change in the crystallization temperature. The X-ray diffraction and adsorption data suggested an increase in the crystallite size and a decrease in the value of limiting adsorption and specific area of magnetite with an increase in the temperature and magnetic field intensity. The nature of surfactants and solvents has a substantial effect on the adsorption process. The IR spectroscopic and equilibrium adsorption data showed that oleic acid has the highest affinity to the surface among the surfactants studied (stearic, oleic, and linoleic acids and sodium oleate). On going from carbon tetrachloride to hexane, the value of limiting adsorption of oleic acid decreases.     

Thermochemistry of explosives

The kinetics constants for the decomposition reaction of an explosive can be used to calculate the lowest temperature (critical temperature, T_m) at which any specific size and shape of explosive can self heat to explosion; however, the accuracy of the calculation is in doubt without an independent experimental determination of a critical temperature for a known size and shape of the explosive. A method is presented for the experimental determination of critical temperatures on a routine basis, and it is shown that agreement between calculated and experimental values is excellent for most common explosives.     

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.     

A quantitative chemiluminescent assay for analysis of peroxide-based explosives

A quantitative chemiluminescent method, enabling indirect identification of the peroxide-based explosives TATP (triacetone triperoxide) and HMTD (hexamethylene triperoxide diamine) has been developed. Treatment of these compounds with acidic solutions produced peroxides, which were transformed into radical derivatives by horseradish peroxidase (HRP) and then quantified by measuring the light emitted during their oxidation of luminol. The method was first developed in the microplate format and later optimized for a portable luminometer, to enable rapid application of the assay directly on site. When the portable luminometer was used each analysis took only 5–10 min. The method had good selectivity, sensitivity, and reproducibility; in the microplate format the limits of detection (LOD) and quantification (LOQ) were 40 and 50 ng mL⁻¹, respectively, for both TATP and HMTD. When the portable luminometer was used the LOD and LOQ were 50 and 100 ng mL⁻¹, respectively, for both compounds. Introduction of light emission-enhancing compounds did not improve the analytical performance of the assay. Imprecision (CV values) was always below 10%. Recovery varied rapidly with time, with an average value of 78% after 5 min. No false-positive result was detected on measurement of a variety of samples; this is an important feature for analysis on site. The method was applied both to contaminated materials and to fortified soil samples, simulating operational conditions.     

A review of conventional explosives detection using active neutron interrogation

Conventional explosives are relatively easy to obtain and may cause massive harm to people and property. There are several tools employed by law enforcement to detect explosives, but these can be subverted. Active neutron interrogation is a viable alternative to those techniques, and includes: fast neutron analysis, thermal neutron analysis, pulsed fast/thermal neutron analysis, neutron elastic scatter, and fast neutron radiography. These methods vary based on neutron energy and radiation detected. A thorough review of the principles behind, advantages, and disadvantages of the different types of active neutron interrogation is presented.     

新型高能炸药热分解研究进展

炸药的热分解对其安定性和库存可靠性等研究是很重要的。本文总结了国内外有关TNAZ(1,3,3-三硝基氮杂环丁烷)、NTO(3-硝基-1,2,4-三唑-5-酮)、LLM-105(1-氧-2,6-二氨基-3,5-二硝基吡嗪)、FOX-7(1,1-二氨基-2,2-二硝基乙烯)等几种新型高能炸药的热分解研究。分别从理论上、实验上阐述了它们的热分解研究现状,指出了以前研究中存在的问题,预测了钝感高能炸药热分解的发展前景。参考文献32篇。     

A review of biosensors and biologically-inspired systems for explosives detection

This article provides a review of the published literature describing the use of biosensors and biologically-inspired systems for explosives detection. The review focusses on the use of antibodies, enzymes, biologically-inspired synthetic ligands and whole-cell biosensors, providing a flavour of the range of technology, formats and approaches that can be used to detect explosives using biological systems.     

A luminescent nanoscale metal-organic framework for sensing of nitroaromatic explosives

The first nanoscale luminescent metal-organic framework has been realized for the straightforward and highly sensitive sensing of nitroaromatic explosives in enthanol solution.     

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

The ultrafast laser-induced photoionization and photodissociation processes of the nitroaromatic containing explosive and explosive related compounds (ERCs) nitrobenzene (NB), 1,3-dinitrobenzene (DNB), m-nitrotoluene (MNT), 2,4-dinitrotoluene (DNT), and 2,4,6-trinitrotoluene (TNT) have been investigated at three laser wavelengths and power densities using a time-of-flight mass spectrometer. Examination of the mass spectra of these compounds reveals the enhanced formation of the molecular ion [M⁺] when ultraviolet (332 nm) and visible (495 nm) light is used relative to infrared (795 nm) radiation. In addition, at 795 nm and a power density of 3. 5 × 10¹⁴ W/cm², the presence of a competition between multiphoton ionization (MPI) and Coulomb explosion (CE) channels is revealed by peak shape analysis, and is thought to be operative under these conditions for all of the molecules investigated.     

Comparison between the effects of superfine steel slag and superfine phosphorus slag on the long-term performances and durability of concrete

Superfine particles have been used as mineral admixtures to enhance physical properties, mechanical properties, and durability of concrete in a lot of research. In this study, superfine steel slag (FSS) and superfine phosphorus slag (FPS) were ground to 643 and 657 m² kg^?1, respectively. The water-to-binder (W/B) ratios were set as 0.45 as well as 0.35, and the cement replacements adopted were 15 and 30%. The effects of FSS and FPS on long-term performance and durability of concrete were investigated. The results show that the increase amplitude of reaction degree of FPS is higher than that of FSS at late age (after 90 days). FPS can improve the pore structure of concrete which is beneficial to the resistance to carbonation and chloride ion penetration for concrete at late age while FSS cannot. FPS is also more advantageous to the development of compressive strength and splitting tensile strength of concrete when compared to FSS at late age. FPS is much more beneficial to the resistance to sulfate attack of concrete while FSS is more disadvantageous to the resistance to sulfate attack of concrete as the replacement ratio increases.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

The magnetocaloric effect of superfine magnets

The magnetocaloric effect (MCE) of aqua suspensions based on superfine magnetite (Fe₃O₄), hematite (α-Fe₂O₃), maghemite (γ-Fe₂O₃), samarium ferrite (SmFe₂O₄) and gadolinium ferrite (GdFe₂O₄) as well as of magnetite-based ferrofluids was calorimetrically determined in the range of the temperatures from 283 to 253 K. MCE has a positive magnitude for all investigated systems except a hematite-based system. For the suspensions on the basis of MCE temperature dependence it was determined that superfine magnetite transformed into α-Fe₂O₃ at the temperature above 328 K in contrast to monocrystal magnetite. For aqua suspensions of samarium ferrite and gadolinium ferrite and magnetite-based ferrofluids MCE temperature dependence has an extreme behavior which is connected with a second-order phase transition. For the first time it is established that the magnetocaloric effect (MCE) is greatly increased when the magnet is a nanosized material.     

A new luminescent metal-organic framework for selective sensing of nitroaromatic explosives

A microporous luminescent metal-organic framework [Zn_4L_2(H_2O)_2].(H_2O)_m(DMA)_n(1)(H_4L=5,5'-((1H-pyrazole-3,5-dicarbonyl)bis(azanediyl))diisophthalic acid, DMA=N,N-dimethylacetamide) was synthesized and characterized by infrared radiation(IR), thermogravimetric analyses(TGA), powder X-ray diffraction spectra(PXRD) and X-ray diffraction. Complex 1has a three dimensional(3D) framework, which can be simplified as 5,5,5,5-c net with the Schlfi symbol of {43.64.83}{44.65.8}{45.65}2. This luminescent metal-organic framework(MOF) shows selectively sensitive to nitrobenzene and series of nitroaromatic explosives such as 4-nitrotoluene, 1,4-dinitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene, and exhibits well recyclability. So complex 1 could be used to detect nitroaromatic explosives as a selective sensing material.     

Selective gas-phase capture of explosives on metal beta-diketonate polymers

A variety of metal beta-diketonate polymers were assessed for gas-phase selective retention of nitro aromatic, nitrate ester, and peroxide explosives. The La(III) complex of p-di(4,4,5,5,6,6,6-heptafluoro-1,3-hexanedionyl)benzene [La(dihed)] showed 13-42 times the retention for the nitro aromatic compounds compared to a control column (identical column but lacking the 5% loading of the metal beta-diketonate polymer). Nitrate esters, the peroxide explosive triacetone triperoxide, and the taggant 1,4-dimethyl-1,4-dinitrobutane were too strongly retained to elute from the La(dihed) column; however, these compounds could be eluted from the less retentive Cu(dihed) or Zn(dihed) columns. A Kováts index of 2124 for 2,4,6-trinitrotoluene (TNT) on the La(dihed) column compared to 1662 on the control illustrates the excellent discrimination against nonpolar hydrocarbons, the principal matrix interference expected in air samples. A proof-of-principle experiment demonstrated analysis of an extrapolated 47 part-per-trillion (ppt) (v/v) of TNT in an air extract concentrate.     

Detonability of aqueous suspensions of explosives

The detonability of aqueous suspensions of solid explosives (pentaerythritol tetranitrate, cyclotrimethylenetrinitramine, cyclotetramethylenetetranitramine) was used as a basis for evaluating the explosion safety of these substances in production and transportation. The dependence of the critical detonation parameters of the suspensions on the content and dispersity of the explosives was determined. A new common method for calculating the critical detonation diameters of suspensions of crystalline explosives in organic media and in water was developed. A novel procedure for preparing uniform sedimentation-resistant aqueous suspensions of crystalline explosives was suggested and developed.     

Chemical ionisation mass spectra of explosives

The chemical ionisation mass spectra of a number of representative explosives have been obtained using hydrogen as reagent gas. Fragmentation modes of the protonated molecular ions tend to be simple although some rearrangements have been noted. Loss of a radical from an even electron parent ion has been observed. The use of ‘ghost spectra’ for confirmation of the molecular weight of the sample is stressed: these consist of ions of low abundance resulting from reactions between sample ions and sample molecules. Labelling studies were carried out using deuterium as reagent gas.