Acetylenic derivatives of betulonic acid amide as a new type of compounds possessing spasmolytic activity

Efficient and versatile synthetic procedures towards novel derivatives of betulonic acid via Mannich reaction, Sonogashira cross-coupling, and copper(i)-catalyzed 1,3-dipolar cyclo-additions were developed. Introduction of secondary amines (Mannich reaction) into betulonic acid amides led to derivatives possessing marked spasmolytic activity, which is not characteristic of the triterpene fragment.     

Heat Transfer of a Cylindrical Body with Catalytic Surface in Subsonic Nonequilibrium Air Plasma Flow

Fluid Dynamics - Steady-state subsonic flows of nonequilibrium air plasma past a cylindrical body with plane face and heat transfer are investigated under the conditions characteristic of testing...     

Modification of GaAs by medium-energy N<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> ions

The modification of GaAs with a 2500-eV beam containing N ₂ ⁺ and Ar⁺ ions is examined with Auger electron spectroscopy. Most implanted nitrogen atoms are found to react with the matrix, substituting arsenic atoms to produce a several-nanometer-thick layer of the single-phase GaAs_1−x N_x (x=6%) solid solution. The GaN phase is absent. Displaced arsenic atoms and nitrogen atoms unreacted with the matrix are present in the layer and on its surface. The former segregate, whereas the latter form molecules.     

Investigation of the extent, rate, and mechanisms of electron-stimulated modification of the C60 fullerite by EELS

A parameter representing the intensity ratio of the two features in the characteristic electron energy loss spectrum that are most sensitive to electron irradiation is proposed for use in characterizing the extent of electron-stimulated modification of fullerite. By normalizing this parameter, we succeeded in obtaining a universal scale for the extent of modification that can be unambiguously related to the π-electron density. The dose dependence of this parameter is shown to be described by one exponential, thus permitting one to conclude that both the polymerization and amorphization of the fullerite are dominated by one mechanism, namely, the formation of intermolecular chemical bonds, which is stimulated by valence-electron excitation. The rate of the electron-stimulated modification, or the dose susceptibility of the material, is defined through the derivative of this parameter. The dependence of this rate on the incident electron energy is obtained. It is shown that structural changes are mainly due to a swarm of numerous secondary and decelerated electrons rather than to the primary electron.     

The effect of the crystalline perfection of quartz on the rotation of the plane of polarization of light

The wavelength dependence of the specific rotation of the plane of polarization of light by quartz crystals is experimentally studied. The chirality coefficients determined from the plots δ(1/λ²) are found to be different for different crystals. The differences between these plots are associated with the perfection of the crystal structure of quartz. The rotation of the plane of polarization is more sensitive to imperfection of the medium and makes it possible to reveal this imperfection without additional irradiation of crystalline quartz by γ quanta.     

Formation and decomposition of nitrides under ion bombardment

The chemical processes of formation and decomposition of narrow-gap nitrides InN and GaAs_{1 ? x} N _x under ion bombardment have been investigated by Auger electron spectroscopy. It is shown that, due to chemical instability, a large fraction of InN decomposes with formation of metal clusters under ion bombardment. It is established that bombardment of GaAs with a beam of N ₂ ⁺ and Ar⁺ ions makes it possible to obtain a chemically homogeneous GaAs_{1 ? x} N _x solid solution with a high nitrogen content (x = 0.1), whereas implantation of only N ₂ ⁺ ions leads to the formation of a mixture of GaN, GaAsN, and GaAs phases. It is concluded that secondary ion cascades, induced by heavy ions, stimulate nitridation reaction, homogenize the spatial atomic distribution, and shift the dynamic equilibrium to the formation of a single-phase solution.     

Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target

Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. The asymmetry depends on the azimuthal angles of both the pion (phi) and the target spin axis (phi(S)) about the virtual-photon direction and relative to the lepton scattering plane. The extracted Fourier component sin((phi+phi(S))(pi)(UT) is a signal of the previously unmeasured quark transversity distribution, in conjunction with the Collins fragmentation function, also unknown. The component sin((phi-phi(S)(pi)(UT) arises from a correlation between the transverse polarization of the target nucleon and the intrinsic transverse momentum of quarks, as represented by the previously unmeasured Sivers distribution function. Evidence for both signals is observed, but the Sivers asymmetry may be affected by exclusive vector meson production.     

Synthesis,properties, and application of 4-nitrosemicarbazones

The studies of the condensation of 4-nitrosemicarbazide (4-NSC) with various aldehydes and ketones resulted in the development of an approach to the synthesis of N-nitrosemicarbazones, promising high-energy and biologically active compounds. Subsequent treatment with amines and alkalis led to the synthesis of water-soluble salts of nitrosemicarbazones, as well as the corresponding semicarbazones. The reaction of N,N′-diisopropyl- or N,N′-di-tert-butyl-1,2-ethanediimine with 4-nitrosemicarbazide led to the synthesis of glyoxal bis(nitrosemicarbazone) derivatives. A computer-aided screening using the PASS software showed a probability of high biological activity for the compounds obtained, whereas antiarrhythmic properties of camphor nitrosemicarbazone potassium salt were confirmed in experiments in rats.