A note on the instability of embeddings of Cauchy-Riemann manifolds

We prove that there are compact strictly pseudoconvex CR manifolds, embedded into some Euclidean space, that admit small deformations that are also embeddable but their embeddings cannot be chosen close to the original embedding. Both authors were partially supported by NSF grants.     

Existence of limiting values of the specific impulse of metal-free composite solid propellants at a preset highest allowable combustion temperature

The influence of the enthalpy of formation and elemental composition of CHNO-formulations on the relationship between the specific impulse and the combustion temperature is studied.     

Existence and uniqueness of the solution of the boundary-value problem for a parabolic equation of unsteady filtration

The problem of the motion of a filtration front in a zero background in the case of a power-law dependence of the filtration coefficient on gas density is considered, and the existence and uniqueness theorem for solutions in the class of analytic functions is proved. The solution is constructed in explicit form, recurrence formulas for computing the coefficients in the series are obtained, and the convergence of the series is proved by the majorant method. The filtration front construction procedure is proposed.     

Kinetics and possible mechanisms of alkaline hydrolysis of alkoxy-<Emphasis Type="Italic">NNO</Emphasis>-azoxy compounds

Hydrolysis rate of alkoxy-NNO-azoxy compounds like di(methoxy-NNO-azoxy)methane I, di-(methyl-NON-azoxy)formal II, di(methoxy-NNO-azoxy)methane III, and 2,2-di(methoxy-NNO-azoxy)propane IV in 5 M KOH solution was measured by manometric method at 80°C; rates relation is 1:40:540:10. Reversible deprotonation to form C-anions followed by their rapid decomposition is a presumable mechanism for compounds I–III. Nucleophilic attack of OH-anion on the carbon atom of CH₃ON=N(O) group is the most probable first stage of hydrolysis in the case of compound IV.     

Kinetics and Mechanism of Thermolysis of Mixtures of Ammonium Nitrate with Polynitro Compounds

Kinetics of heat release in thermolysis of mixtures of ammonium nitrate with bis(2,2,2-trinitroethyl) succinate, tetrakis(2,2,2-trinitroethyl) orthocarbonate, technical-grade trinitrotoluene and of the individual polynitro compounds was studied. The temperature dependences of the initial rates of the processes and the time required to attain the maximal rate were determined. A thermolysis mechanism of these mixtures was suggested and the dependence of the thermolysis rate on the properties of the polynitro compounds was accounted for.     

Combustion of zirconium-containing model compositions of solid propellant

The features of combustion of model compositions of a composite solid rocket propellant containing zirconium at a concentration of up to 40 wt % are investigated. Burning rates at pressures of from 20 to 80 atm and the parameters of the combustion law are measured. Comparison with combustion of similar aluminum-based compositions is carried out. Compositions with compound (zirconium along with aluminum in various proportions) metal fuels are investigated. The application of zirconium as a metal fuel is shown to substantially increase the burning rate in comparison with compositions based on aluminum.     

Prospects for the use of diethynylbenzene as a fuel dispersant for rocket ramjet engines

Russian Chemical Bulletin - The applicability of 1,4-diethynylbenzene (DEB) as a dispersant of solid fuels was studied. The atmospheric flight ranges of an aircraft with a rocket ramjet engine...