Diagnostic techniques in deflagration and detonation studies

Abstract

Advances in experimental, high-speed techniques can be used to explore the processes occurring within energetic materials. This review describes techniques used to study a wide range of processes: hot-spot formation, ignition thresholds, deflagration, sensitivity and finally the detonation process. As this is a wide field the focus will be on small-scale experiments and quantitative studies. It is important that such studies are linked to predictive models, which inform the experimental design process. The stimuli range includes, thermal ignition, drop-weight, Hopkinson Bar and Plate Impact studies. Studies made with inert simulants are also included as these are important in differentiating between reactive response and purely mechanical behaviour.

Graphical abstract

相似文献   

Determination of chlorpyrifos and its metabolites in rat brain tissue using coupled-column liquid chromatography/electrospray ionization tandem mass spectrometry

A method has been developed to quantify chlorpyrifos (O,O-diethyl-O-[3,5,6,-trichloro-2-pyridyl] phosphorothionate) and its metabolites chlorpyrifos-oxon (O,O-diethyl-O-[3,5,6,trichloro-2-pyridinyl] phosphate) and TCP (3,5,6,-trichloro-2-pyridinol) in rat brain tissue by coupled-column liquid chromatography/electrospray ionization tandem mass spectrometry (LC/LC/ESI-MS/MS). Rat brains were homogenized and treated by protein precipitation using ice-cold acetonitrile. The supernatant was directly injected onto the coupled-column system. Sample clean-up was achieved on a Zorbax Extend-C(18) column (2.1 x 50 mm, 5 microm) using a mobile phase of acetonitrile/water with 0.0025% formic acid (40:60, v/v). The compounds were separated isocratically on a Zorbax Eclipse XDB C(8) column (2.0 x 150 mm, 5 microm) using a mobile phase of acetonitrile/water with 0.0025% formic acid (75:25, v/v). Chlorpyrifos and chlorpyrifos-oxon were detected in positive ion mode using multiple reaction monitoring (MRM). TCP was detected in negative ion mode using precursor-to-precursor transition monitoring. The method was validated and the specificity, linearity, limit of quantitation (LOQ), precision, accuracy, stability, and recoveries were determined. Calibration curves for all three analytes yielded correlation coefficients of 0.993 or greater. The LOQs were 25.3 ng/g for chlorpyrifos and 6.3 ng/g for chlorpyrifos-oxon and TCP. All precision relative standard deviations (RSDs) were less than 16% for the LOQ and less than 11% for the other QC samples. This method was successfully applied to six rats that were injected subcutaneously with chlorpyrifos.     

On the biosynthetic origin of methoxymalonyl-acyl carrier protein, the substrate for incorporation of "glycolate" units into ansamitocin and soraphen A

Feeding experiments with isotope-labeled precursors rule out hydroxypyruvate and TCA cycle intermediates as the metabolic source of methoxymalonyl-ACP, the substrate for incorporation of "glycolate" units into ansamitocin P-3, soraphen A, and other antibiotics. They point to 1,3-bisphosphoglycerate as the source of the methoxymalonyl moiety and show that its C-1 gives rise to the thioester carbonyl group (and hence C-1 of the "glycolate" unit), and its C-3 becomes the free carboxyl group of methoxymalonyl-ACP, which is lost in the subsequent Claisen condensation on the type I modular polyketide synthases (PKS). d-[1,2-(13)C(2)]Glycerate is also incorporated specifically into the "glycolate" units of soraphen A, but not of ansamitocin P-3, suggesting differences in the ability of the producing organisms to activate glycerate. A biosynthetic pathway from 1,3-bisphosphoglycerate to methoxymalonyl-ACP is proposed. Two new syntheses of R- and S-[1,2-(13)C(2)]glycerol were developed as part of this work.     

Nondissociative adsorption of H2 molecules in light-element-doped fullerenes

First-principles density functional and quantum Monte Carlo calculations of light-element doped fullerenes reveal significantly enhanced molecular H2 binding for substitutional B and Be. A nonclassical three-center binding mechanism between the dopant and H2 is identified, which is maximized when the empty p(z) orbital of the dopant is highly localized. The calculated binding energies of 0.2-0.6 eV/H2 is suited for reversible hydrogen storage at near standard conditions. The calculated H2 sorption process is barrier-less, which could also significantly simplify the kinetics for the storage.     

Durability and cleaning of matt surface ceramic colour standards

Matt surfaced versions of the Ceramic Colour Standards are produced by CERAM Research by means of an abrasion technique applied to the normally gloss surface. These are available as an alternative to the existing matt standards made from opal glass, pressed powder and ‘plastic'. The existing standards have good matt surfaces but generally have a comparatively short life due to the delicate nature of the surface. This causes problems in maintaining continuity of measurement. The Ceram Research matts also have a good matt surface which, being ceramic should be durable. This paper reports the results of a series of measurements made on selected standards, which show that the standards are durable. In addition it was found that it was possible to clean the standards, returning them close to their original colour values.     

Sequential multiphoton ionization spectroscopy: extension of a useful spectroscopic tool

An adaptation of multiphoton ionization spectroscopy is presented in which a single vibrational—rotational level of an excited electronic state is pumped using a dye laser, and a second, independently tunable dye laser beam induces multiphoton ionization from this excited level. Several advantages of this technique are demonstrated using molecular iodine.     

Syntheses and crystal structures of two N-substituted thio-imidazoles

The syntheses and structures of two N-substituted thio-imidazoles are reported. The geometrical parameters for both compounds, including essentially planar imidazole rings, are consistent with previous structural studies of related materials. The only possible non-van der Waals’ interactions influencing the molecular packing are weak C–H⋯π bonds. Crystal data: C₁₂H₁₄N₂S (N-methyl-N′-2-phenylethyl-imidazol-2-thione), M _r = 218.31, monoclinic, P2₁/n, (No. 14), a = 6.8441(2) ?, b = 12.9960(4) ?, c = 13.4703(4) ?, β = 97.7729(16)°, V = 1187.12(6) ?³, Z = 4, R(F) = 0.039, wR(F ²) = 0.104. C₁₉H₂₀N₂S (N,N′-bis((s)-1-phenylethyl)imidazol-2-thione), M _r = 308.43, orthorhombic, P2₁2₁2₁ (No. 19), a = 10.4060(3) ?, b = 10.6712(3) ?, c = 14.8932(3) ?, V = 1653.81(7) ?³, Z = 4, R(F) = 0.038, wR(F ²) = 0.085.