Homogeneous Stäckel-type systems

A class of Hamiltonian dynamic systems integrated by the variable separation method is considered. The integration for this class is the inversion of an Abel mapping on hyperelliptic curves. We prove that the derivative of the Abel mapping is the Stäckel matrix, which determines a diagonal Riemannian metric and curvilinear orthogonal coordinate systems in a flat space. Lax representations with the spectral parameter are constructed. The corresponding classicalr-matrices are dynamic. It is shown how the class of pointwise canonical transformations can be naturally generalized using the Abel integral reduction theory.     

Synthesis of sterically hindered aromatic dialdehydes

A study was carried out on the formylation of a series of aromatic compounds containing two mesitylene or durene residues [dimesityl (I), dimesitylmethane (II), 1,2-dimesitylethane (III), 1,6-dimesitylhexane (IV), dimesityl sulfide (V), 1,1-dimesitylethylene (VI), 1,1-dimesityl-1-butene (VII), and didurylmethane (VIII)] by the action of dichloromethyl methyl ether (DCM) in the presence of A1C1₃ and TiCl₄. The corresponding dialdehydes are the major products. The formylation products when the reaction is carried out in the presence of A1C1₃ in the case of (I) and (V) contain significant amounts of monoaldehydes, while partial cleavage of the substrates with the formation of products containing only one benzene ring is observed in the case of (II) and (VIII) in addition to formylation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1700–1703, July, 1991.     

Synthesis of Substituted 6-Amino-4-aryl-5-cyano-2H,4H-pyrano[2,3-c]pyrazoles. Crystal and Molecular Structure of 6-Amino-5-cyano-3-methyl-4-(2',4',6'-triethylphenyl)-2H,4H-pyrano[2,3-c]pyrazole

Substituted 6-aminopyrano[2,3-c]pyrazoles were synthesized by the two-component condensation of arylidenemalononitriles and substituted 5-pyrazolones or three-component condensation of aromatic aldehydes, malononitrile, and substituted 5-pyrazolones. It was established by X-ray crystallographic analysis that pyranopyrazoles exist in the 2H and not the 1H tautomeric form.     

Polyalkoxybenzenes from plant sources 2. Synthesis of isoxazoline analogs of combretastatin from natural allyl(methylenedioxy)methoxybenzenes

A series of analogs of the natural mitostatic agent combretastatin were synthesized by the reaction of nitrile oxides with natural allylbenzenes, such as myristicin, apiol, and dillapiol. The 1,3-dipolar cycloaddition reactions in allylic systems proceed regiospecifically. The reactions with trans isomers of propenylbenzenes, viz., isomyristicin, isoapiol, and isodillapiol, as dipolarophiles produce regioisomers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2375–2380, December, 2007.     

Synthesis of sterically hindered aromatic aldehydes

Formylation of mesitylene, durene, and m-xylene derivatives containing electron-donor and electron-acceptor substituents by dichloromethyl methyl ether was studied in the presence of TiCl₄. A series of functionally substituted sterically hindered benzaldehydes was prepared from the products of these reactions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1609–1615, July, 1991.     

Ammonia decomposition on a platinum nanocoating at various electric potentials

It was shown that the rate of ammonia decomposition on a platinum nanocoating can be controlled by applying an external electrostatic field to the coating to create a negative or positive platinum potential of variable magnitude. In experiments conducted with a contact time of 15 min between platinum and ammonia at a temperature of 700 K and a pressure of 5 × 10^–7 Torr, the decomposition rate increased by 44% at a negative potential of the coating of–6 V and by 70% at a positive potential of +6 V.     

Pursuit-evasion predator-prey waves in two spatial dimensions

We consider a spatially distributed population dynamics model with excitable predator-prey kinetics, where species propagate in space due to their taxis with respect to each other's gradient in addition to, or instead of, their diffusive spread. Earlier, we have described new phenomena in this model in one spatial dimension, not found in analogous systems without taxis: reflecting and self-splitting waves. Here we identify new phenomena in two spatial dimensions: unusual patterns of meander of spirals, partial reflection of waves, swelling wave tips, attachment of free wave ends to wave backs, and as a result, a novel mechanism of self-supporting complicated spatiotemporal activity, unknown in reaction-diffusion population models.