Synthesis,structure, and acid-base characteristics of enaminones of the barbituric acid series

Enaminones were obtained by a tricomponent condensation of barbituric acids, aniline and triethyl orthoformate. The acid-base properties, PMR, UV and IR spectra of 5-anilinomethylene- and 1,3-dimethyl-5-anilinomethylenebarbituric acids are discussed. The properties of these compounds conform with a bipolar structure, in which the positive charge is distributed over the exocyclic part of the molecule, while the negative charge is distributed on the -dicarbonyl fragment of the heterocyclic ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 952–956, July, 1988.     

Toroid type high-pressure device: history and prospects

The Toroid type high-pressure device and its predecessor, the Chechevitsa (lentil) type high-pressure device, are known to be used efficiently for the synthesis of new materials in recent decades. It was through the Chechevitsa device the first ultradense modification of silica, ‘stishovite’, was obtained. Both devices were essential for the industrial production of superhard materials in the USSR and other socialist countries. In 1980s, almost half of the world synthetic diamond and c-BN products were manufactured by these devices. However, the application of the Toroid device for examining the structure and physical properties of highly compressed substances has been considerably less appreciated. Meanwhile, the device has some unique features that have made possible 35-years of an extensive investigation of physical properties of substances at pressures up to 150 kbar, including electron transport and thermodynamic properties, elastic characteristics, viscosity, thermo-conductivity and other physical properties. Also, the device has been widely employed for structural X-ray and neutron diffraction studies of many materials. But it is not until recently that the convenience of the Toroid device for physical studies has been fully recognized. Through this recognition, the Toroid type device is today becoming increasingly popular among the researchers in the field of high pressures around the world.     

Thermoexoelectronic and thermoluminescent properties of transparent YAG:Nd and YAG:Yb nanoceramics

Preliminary investigations of thermoluminescent and thermoexoelectronic properties of transparent microstructured YAG:Nd and YAG:Yb ceramics are performed. Five peaks of thermostimulated luminescence are found for YAG:Nd in the VUV and UV ranges. Four and six peaks of thermostimulated exoemission are found for YAG:Yb and YAG:Nd, respectively. The parameters of carrier traps are calculated.     

Thermal ionization decay of E′ centers in germanium dioxide

The thermally induced decay of oxygen-deficient E′ centers in GeO₂ glasses and ceramics has been studied experimentally and theoretically. The electron emission effect, which accompanies the thermally induced decay of these defects, has been interpreted based on the Perel’-Karpus model for the multiphonon ionization of centers in an electric field. It has been established that the decay of E′ centers in amorphous and crystalline modifications of GeO₂ is reversible and occurs according to the thermal ionization mechanism.     

Exoelectron Emission of a Carbon Nanomaterial

The exoemission properties of a Taunite carbon nanomaterial consisting of nanosized multiwalled nanotubes and nanofibers were investigated by thermally stimulated exoelectron emission (TSEE). The TSEE spectra of the carbon nanomaterial differed from the spectra of pressed graphite. It was assumed that defect—adsorbate complexes were emission-active centers on the surface of the nanomaterial     

Tautomeric Transformations and Reactivity of Polyfunctional Hydroxypyrimidines: III. Tautomerism of 5-Acyl Derivatives of Hydroxypyrimidines and Formation of H-bonded Complexes with Solvents

Tautomerism of 5-formyl- and 5-acetyl derivatives of pyrimidine-2,4,6-trione, 2-thioxopyrimidine-4,6-dione, and 4,6-dihidroxy-2-methylthiopyrimidine was studied by NMR, UV, and IR spectroscopy, as well as by quantum chemistry. An equilibrium mixture of exo- and endo-enols in the neutral state and the presence of the same tautomers in monoanions were found. The energies of intramolecular hydrogen bonds in the gas phase and their changes in going to solutions in water, DMSO, and chloroform were calculated. The energies of intra- and intermolecular hydrogen bonds are close to each other. This fact suggests existence in solutions of two forms: tautomers with intramolecular H bond and H-bonded complexes with the solvents studied, whose formation involves cleavage of the intramolecular H bond. Characteristics of intermolecular hydrogen bonds are determined by the relative proton-donor and proton-acceptor powers of polyhydroxypyrimidines and solvents and are almost independent of the polarity of the medium.     

Electronic Work Function of Carbon Nanocomposite Films According to Vacuum and Atmospheric Photoemission

Technical Physics - Using the methods of optically stimulated electron emission (OSEE) and ambient pressure photoemission spectroscopy (APS), the energy characteristics of carbyne-containing films...     

Reactor laser using a mixture of xenon with uranium hexafluoride

The possibility is considered of developing a reactor laser based on a mixture of xenon, uranium hexafluoride, and a buffer gas. The kinetic scheme of populating the xenon monofluoride exciplex is analyzed. The conditions for the possibility of less stringent requirements on the nuclear pumping intensity are investigated. The conditions that ensure the necessary heat dissipation under various reactor-laser operating conditions are considered. It is shown that in principle supersonic flow of the working gas can ensure energy output in the form of laser radiation.Translated from Trudy Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 120, pp. 43–50, 1980.