Thermal Behavior of Hexogen Phlegmatized with Montan Waxes

Hexogen can be used pressed only if its crystals are covered by some polymeric material [1], either natural or artificial. Montan waxes, as natural polymeric materials, were used for the phlegmatization. The melting process of seven types of waxes was analyzed by differential scanning calorimetry. The thermal decomposition processes of hexogens and phlegmatized hexogens were investigated by dynamic differential scanning calorimetry and dynamic thermogravimetric analyses. Kinetic parameters of the decomposition processes of hexogens were evaluated by using data obtained from differential scanning calorimetric curves. This revised version was published online in August 2006 with corrections to the Cover Date.     

The generator coordinate method for tertiary reactions of light composite nuclei

A theory of nuclear reactions with three composite fragments in a final channel, based on a variational principle of Kohn type and the generatorcoordinate (GC) representation of the trial function, is proposed and tested numerically. The Hamiltonian operator is microscopic, and the GC basis enables the inclusion of any rearrangement channels. The trial function is totally antisymmetrized and exactly projected on the eigenstates of the angular momentum and parity operators. It consists of a correlation term and channel terms which have to be specified only in the regions not covered by the correlation term, in which a pair of fragments is not close together. The channel relative-motion wave functions, from which the GC representation of the channel terms is obtained, are calculated from an asymptotic series. The three-fragment part of the trial function is expanded in hyperspherical harmonics. In this paper we study primarily the convergence of the reaction parameters with respect to the GC basis applying the formalism to the reaction³He(³He,pp)⁴He without inclusion of the Coulomb interaction. The part of the rearrangement differential corss section corresponding to well-separated final fragments is compared to experimental data.     

On a problem in condensed two-phase combustion

An exothermic binary chemical reaction of first order is studied, assuming that one of the reactants can undergo a change of phase. In the limit of low activation energy, a one-dimensional problem is considered and the well-posedness of the corresponding system of two parabolic equations with a free boundary is proved in a classical sense.     

Synthesis of a novel series of 4,4-disubstituted 2,3,4,7-tetrahydroazepines

A general, simple and straightforward strategy for the synthesis of a novel series of 4,4-disubstituted 2,3,4,7-tetrahydroazepines is described. This route involves a one-pot Wittig olefination/N-allylation process on a five-membered hemi-aminal followed by a final ring closing metathesis reaction.     

Quasi-contraction on a cone metric space

In this work we define and study quasi-contraction on a cone metric space. For such a mapping we prove a fixed point theorem. Among other things, we generalize a recent result of H. L. Guang and Z. Xian, and the main result of ?iri? is also recovered.     

High pressure fast-flow technique for gas phase kinetics studies

A fast-flow technique suitable for measuring elementary rate constants over a wide range of pressures has been developed. The method operates under turbulent flow conditions, in contrast to laminar flow which characterizes the conventional low pressure technique. Flow visualization, velocity profile measurements, and tracer pulse studies have been carried out in a flow tube reactor to investigate the dynamics of both laminar and turbulent flow for chemical kinetics purposes. Furthermore, the wall collision frequency for the reactants has been determined: at the higher pressures it is greatly reduced in comparison with the frequency characteristic of the conventional low pressure laminar flow technique. Also, to test and validate the technique the bimolecular rate constants for the reactions H+Cl₂ and H+O₃ have been measured at total pressures in the 3–300 torr range; at pressures below 5 torr, as well as above 50 torr in the turbulent flow regime the agreement with the recommended literature values is excellent. © 1993 John Wiley & Sons, Inc.