Determination of energies of cosmic-ray nuclei in the region above 1 TeV

A method is proposed for measuring energies of particles in the region above 1 TeV. The method is based on detecting the greatest specific energy deposition in hadronic cascades propagating in dense matter. This makes it possible to improve accuracy in measuring energy by thin calorimeters in studying the energy spectra of high-energy cosmic rays at high altitudes. Attainable accuracies in measuring energy are considered for protons and He nuclei. The results of a relevant simulation are compared with the results of a satellite-borne experiment with Kosmos-1713.     

Synthese in fester Phase. Nachweis und Ausma? von Reaktionen innerhalb des Harzes

Ohne Zusammenfassung     

Scattering by a potential well in an intense radiation field

Scattering by a spherically symmetric potential well in a laser radiation field is examined in the eikonal approximation. The total scattering cross section is found for radiation of an arbitrary number of photons. The range of values of the Born parameter is obtained for which the influence of the radiation field on the scattering cross sections is significant.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 73–76, April, 1989.     

An efficient procedure for the preparation of 4-substituted 5-aminoimidazoles

The preparation of O-methylimidates from alpha-aminonitriles and their subsequent co-cyclization with primary amines to afford 4-substituted 5-aminoimidazoles was studied. It was found that the mildly acidic pyridinium p-toluenesulfonate efficiently catalyzed each stage of the reaction sequence: (a) the formation of the O-methylimidates, (b) their co-cyclization with a variety of primary amines, and (c) certain derivatizations of the resultant heterocycles. The developed reaction conditions tolerate a wide variety of alpha-aminonitriles and primary amine co-reactants. Thus, it is possible to easily prepare a diverse array of substituted heterocyclic compounds in good yield. The requisite alpha-aminonitriles were synthesized either from amino acids or by phase-transfer alkylation of a glycine anion equivalent. The unstable free 5-aminoimidazoles were normally protected in situ to provide derivatives (methyl imidates or N,N-dimethylamidines) that were amenable to characterization.     

Some features of the kinetics and mechanism of polypropylene autoxidation under tensile stress

The influence of tensile stress on different stages of the chain oxidation of polypropylene (PP) has been studied. The degrees of oxidation at various sites of the stressed samples, oxidized up to failure, were determined by i.r. spectroscopy using a focussed beam; the scanning was performed along the samples from the fracture site to the clamps. The change in the mechanism of initiation of oxidation with increasing stress was shown to be accompanied by a decrease in the propagation rate and an increase in the termination rate (with the participation of quickly decaying terminal radicals) and this led to a sharp decrease in the oxidation chain length. Consequently, inhibitors of chain oxidation become ineffective under high stresses and therefore do not increase polymer durability. The oxidation of stressed PP is shown to be local in nature; a defect detection process in oxidizing stressed PP is proposed based on the differences in product composition and concentration in stressed sites (matrix) and relaxed sites (near the cracks).