Thermal Transformations of Cubane Derivatives

The thermal degradation of the cubane moiety in 1,4-cubanedicarboxylic acid, its dimethyl ester, and 1,4-dibromocubane in a condensed state were studied by calorimetry. The kinetic parameters and the composition of products, as determined by ¹H and ¹³C NMR spectroscopy, are consistent with a biradical reaction mechanism. The presence of carboxyl groups capable of resonance conjugation stabilizes a biradical and increases the rate of isomerization of the acid and ester by a factor of 20, as compared with that of cubane. Bromine as a substituent has almost no effect on the rate of cubane thermolysis. The primary biradical is rapidly isomerized to corresponding cyclooctatetraene derivatives. A detailed reaction scheme is presented, and the relative rates of individual steps of the process are considered.     

Method of Bayesian estimates in the problem of laser gas analysis

The problem of reconstructing gas concentrations is considered for laser multicomponent gas analysis. For the differential absorption method, the procedures of signal processing are described based on the method of Bayesian estimates. It is demonstrated that the use of the method of Bayesian estimates the problem of reconstructing gas concentration both for few-and multicomponent gas mixtures allows to be solved effectively even for gases whose absorption spectrum has no noticeable maxima. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 29–35, September, 2008.     

N-Substituted tetrahydro-1,3-oxazines and oxazolidines. 1. A new version of the Mannich reaction involving amino alcohols

A new version of the Mannich reaction involving amino alcohols (3-aminopropan-1-ol and aminoethanol) was developed. These compounds react with formaldehyde and CH or NH acids to give N-substituted tetrahydro-1,3-oxazines or oxazolidines.     

Destruction of polymeric cobalt(ii) trimethylacetate. Synthesis and structures of new complexes Co9(μ3-OH)6(μ-OOCCMe3)12(OCMe2)4 and Co6(μ4-O)2(μ-OOCCMe3)10(η-HOOCCMe3)4

Russian Chemical Bulletin -     

Calculating the characteristics of neutron-deuteron and proton-deuteron systems in a two-body potential model

³H and ³He nuclei are considered in a two-body model (³H = n + d; ³He = p + d). Two independent approaches are used: in the first, interaction is described by the folding potential, while NN potentials are taken in the Hulthen form with allowance for violations of isotopic invariance. The second approach features phenomenological Hulthen and Yukawa Nd potentials used as Nd interaction. In both approaches, the binding energies, vertex constants, and asymptotic normalization coefficients in the N+d channel are calculated.     

Non-Algebraic Quadrature Domains

It is well known that, in the plane, the boundary of any quadrature domain (in the classical sense) coincides with the zero set of a polynomial. We show, by explicitly constructing some four-dimensional examples, that this is not always the case. This confirms, in dimension 4, a conjecture of the second author. Our method is based on the Schwarz potential and involves elliptic integrals of the third kind.     

Characteristics of scattering of Λ hyperons from nuclei within the potential model

The characteristics of bound states of hypernuclei were calculated in [1] in a wide range of mass numbers within the potential model for three different potentials. In this study, the phase shifts and low-energy parameters for scattering of Λ hyperons from core nuclei, considered in [1], have been calculated for the same potentials. The calculated scattering lengths and effective radii are compared with their values found in [1] on the basis of the data on the binding energies and vertex constants of hypernuclei.     

Nanodiamonds thermoluminescence

Nanodiamonds thermoluminescence was studied. It was compared with thermoluminescence of synthetic diamonds of relative purity, weakly and strongly boron-doped. A dependence of the nanodiamond thermoluminescence on an irradiation dose was examined.