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Drop-weight experiments are performed on a thin layer of cyclotetramethylene tetranitramine (HMX) explosive crystals. The drop-weight impact machine is equipped with high-speed photographic systems. Experimental results show the effects of drop heights, mass of particles, and distributed density on compaction, deformation, transparency, reaction violence, and burning propagation. The aim is to establish a link between mechanical and thermal responses for a single layer of granular explosives. Minimum input energy and adequate number of particles, as well as sufficient mutual interactions among particles in the granular explosive sample, are necessary prerequisites for hot spot ignition and growth to burning. The course of the response, instead of a simple “go” or “no go” criterion is emphasized as a critical consideration in ranking material sensitivity. [ABSTRACT FROM AUTHOR]

A polyoxomolybdate, [Cu2(pz)(Mo3O10)] n (pz = pyrazine) (1), has been synthesized hydrothermally and characterized by elemental analysis, IR, X-ray photoelectron spectra, and thermogravimetric analysis. Single-crystal X-ray diffraction demonstrates that 1 has a 3-D architecture constructed by combination of {Mo3O10} units and [Cu2(pz)]2+. All the terminal oxygen atoms of the polyoxomolybdate are coordinated by univalent copper. Pyrazine came from in situ decarboxylation of 2-pyrazinecarboxylic acid and Cu+ from the in situ reduction of Cu2+ during the hydrothermal synthesis. [ABSTRACT FROM PUBLISHER]

A series of novel 6-(aroxymethyl)-2-aryl-6,7-dihydropyrazolo[5,1-c][1,4] oxazin-4-one derivatives was synthesized from ethyl 3-aryl-1H-pyrazole-5-carboxylate and 2-aryloxymethylepoxide by a microwave-assisted, one-step method in good yields. The microwave-assisted reaction of ethyl 3-aryl-1H-pyrazole-5-carboxylate and 2-aryloxymethylepoxide proceeds with higher regioselectivity and is more economical and environmentally friendly in contrast to the normal intramolecular esterification route. A tandem mechanism of the reaction was proposed. [ABSTRACT FROM AUTHOR]

Phase behavior of aqueous mixed surfactants, 1,3‐propanediyl bis(dodecyl dimethylammonium bromide) and sodium dodecyl sulfonate, has been studied at 318.15 K. The influence of added sodium halides (NaF, NaCl, and NaBr) has been investigated. For those systems studied, only one aqueous two‐phase region is formed in which cationic gemini surfactant is in excess. Different salt effects on the densities of the concentrated phases in aqueous two‐phase systems were observed for the three sodium halides. Density experiments indicate that contributions of various ions and water to the density of the solutions are near additive. Whether the concentrated phases in aqueous two‐phase systems are the bottom phases with higher densities or not are dependent on the different counterion binding ability and on the different contribution to the density of the three halides. [ABSTRACT FROM AUTHOR]