Some new aspects of the theory of radioanalytical methods based on the partial solvent extraction separation of the element to be determined

Interrelationship between the error of the radioanalytical methods and the concentration of the element to be determined has been found for extraction systems with different parameters K_ex, pH, a concentration of the extractant. Based on a mathematical discussion of this interrelationship, the criterion of the estimation of sensitivity has been proposed for the different radioanalytical methods based on the substoichiometric principle as well as some deviations from it.     

M?glichkeiten der Methode der Registrierung der W?rme(Infrarot)strahlung bei der Untersuchung der Natur der Spannungen in Polymeren

Ohne Zusammenfassung     

Spin-wave theory for finite classical magnets and superparamagnetic relation

Analytical calculations based on finite-size spin-wave theory and Monte Carlo (MC) simulations are performed to investigate the validity of the well-known relation m(H, T) = M(H, T)B _D[M(H, T) H/T] between the induced magnetization m of the magnetic particle and its intrinsic magnetization M for the Ising and isotropic classical models (B _D(x) is the Langevin function, D is the number of spin components, is the number of atoms in the particle). It follows from general arguments and from our analytical results for the Heisenberg model at T≪T _c that this relation is not exact for any finite D and nonzero temperature. Nevertheless, corrections to this formula remain very small practically in the whole range T < T _c if ≫ 1, as confirmed by our Monte Carlo calculations. At T T _c/4 there is a good agreement between the MC and finite-size spin-wave calculations for the field dependence of m and M for the Heisenberg model with free boundary conditions. Received 1st December 2000     

Standard enthalpies of formation of some N-spiranes

The heats of combustion of three compounds, members of a new series of N-spiranes were measured by combustion calorimetry. The molecules of the title compounds comprise condensed and N-spirofused heterocycles as well as nitroxy groups that are both NO-donors and explosophores. The enthalpies of formation and the heats of explosive transformation of these compounds are calculated. Two compounds belong to explosives with low heat of explosive transformation, whereas the third compound is inert.     

Energetic properties and impact sensitivity of crystalline explosives

The impact sensitivity of some groups of nitrates and cubane derivatives has been correlated with their heat of explosion and chemical structure. These correlations show the ways of reducing explosion hazard in handling these compounds. It is currently impossible to construct a reference series of compounds that would allow explosives with preset sensitivity to be synthesized on the basis of a preliminary energetic prediction. New opportunities to enhance safety in handling explosives can be provided by investigating their detonation ability.