One-pot synthesis of polysubstituted 1,2,3,4-tetrahydropyridines

Mono- and bicyclic 1,2,3,4-tetrahydropyridine derivatives have been synthesized in up to 98% yield by one-pot three-component condensation of ethyl acetoacetate with methoxymethanol and primary amines (diamines) in methanol in the presence of tert-butyl alcohol.     

Formation of wide-aperture electron beams in electron accelerators with explosive emission cathodes

The problems concerning the formation of electron beams of microsecond duration, electron energy 500–600 keV, and current density up to 20–30 A/cm² with a rectangular cross section of area 0.1–1 m² in high-current electron accelerators with explosive emission cathodes are considered. The designs of vacuum diodes capable of producing such beams to be used in high-power lasers and for ionization of gas in large volumes are presented. Institute of High-Current Electronics, Siberian Division of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 87–91, April, 2000.     

Coulometric Determination of the Antioxidant Capacity of Tea Extracts Using Electrogenerated Bromine

A coulometric procedure based on the reaction between aqueous extracts of tea with electrogenerated bromine compounds was proposed for the rapid estimation of the antioxidant capacity of different kinds of tea. The antioxidant properties of tea with respect to bromine are mainly due to naturally occurring flavonoids, tannins, and some vitamins. Photometric and coulometric data for black teas exhibit good correlation.     

Modification of Ti foils irradiated by intense heavy ion beams

ABSTRACT

Modification of Ti foils irradiated by intense energetic heavy ion (HI) beams in long-term experiments has been considered. The experiments on the synthesis of superheavy nuclei, which are carried out in Dubna with a gas-filled recoil separator (DGFRS), determine the conditions of such experiments. High intensities of HIs passing through a relatively small area and thickness of the foils, as well as their heating by a beam, are inherent in such experiments. The ability of the foils to withstand radiation damages, sputtering, and evaporation of atoms becomes questionable. All the processes seem to be dependent on temperature, and none of them is independent of the others, but they can be considered separately. In this work, sputtering yields are estimated on the grounds of available models and experimental data and compared with the results of measurements carried out to verify the estimates. The foil temperature, in turn, can be estimated in the conditions of pulse heating followed by subsequent cooling with radiation emitted from their surfaces. These conditions correspond to the rotating Ti entrance window irradiated by a continuous HI beam in the DGFRS experiments.     

Preparation of Nanosized Tungsten and Tungsten Oxide Powders

Physics of the Solid State - Nanopowder tungsten oxide and metallic tungsten are obtained via pyrolysis of ammonium metatungstate. Two methods are used for the synthesis of tungsten oxide: the use...     

Cyclothiomethylation of carboxylic acid hydrazides with aldehydes and H<Subscript>2</Subscript>S

The cyclothiomethylation of carboxylic acid hydrazides RCONHNH₂ (R = C₅H₄N, Ph, 2-MeOC₆H₄, or 4-HOC₆H₄CH₂) with formaldehyde and H₂S at 70 °C affords predominantly the corresponding N-(1,3,5-dithiazinan-5-yl)amides, whereas this reaction at 0–−50 °C gives a mixture of the latter compounds with 3-acyl-1,3,4-thiadiazolidines. N-(1,3,5-Dithiazinan-5-yl)-amides were selectively synthesized by the reaction of carboxylic acid hydrazides with formaldehyde and H₂S in the presence of BuONa in BuOH.     

A new approach to the group analysis of one-dimensional stochastic differential equations

Stochastic evolution equations are investigated using a new approach to the group analysis of stochastic differential equations. It is shown that the proposed approach reduces the problem of group analysis for this type of equations to the same problem of group analysis for evolution equations of special form without stochastic integrals.     

Synthesis,molecular structure,conformation and biological activity of Ad-substituted N-aryl-tetraoxaspiroalkanes

An efficient method has been developed for the synthesis of 7′-arylspiro{adamantane-[2,3′]-(1′,2′,4′,5′,7′-tetraoxazocanes)} by the ring transformation reaction of spiro{adamantane-[2,3’]-(1′,2′,4′,5′,7′-pentaoxacane)} with arylamines in the presence of Sm(NO₃)₃·6H₂O as the catalyst. NMR signals of the synthesized compounds were assigned considering the conformation dynamics of the tetraoxazocane ring with two rigid peroxide bonds. The structures of some of the compounds were studied by X-ray diffraction. The thermal stability of single crystal was determined by DSC method. Compounds 7′-(2-methylphenyl)spiro{adamantane-[2,3′]-(1′,2′,4′,5′,7′-tetraoxazocane)} and 7′-(4-fluorophenyl)spiro{adamantane-[2,3′]-(1′,2′,4′,5′,7′-tetraoxazocane)} exhibited cytotoxicity towards cancer cells.