Interaction of spiro-heterocyclic oxindole system with sodium diformylimide

New functionalized condensed benzazoles have been synthesized based on isatin, 3,4-diaminofurazane, and sodium diformylimide.     

Intensity resonances in a double-mode HeNe/CH4 laser with synchronized modes

4 gas laser with an intracavity absorbing cell is studied experimentally and theoretically at a modulation frequency approximately equal to the intermode beat frequency. It is revealed that in the vicinity of the absorption-line centre the intensity of every mode for certain system parameters displays resonance structures narrower than the homogeneous line width of the absorption line. This occurs when the range of mode synchronization is near the absorption-line centre and its size is less than the homogeneous width of the absorption line. Received: 29 February 1996/Revised version: 4 February 1997     

Technology of polishing of titanium surface using the fiber-laser radiation

The effect of the radiation of the pulsed fiber laser on the surfaces of cylindrical samples made of the VT16 titanium alloy is studied. It is demonstrated that the irradiation at appropriate parameters of the laser radiation in the inert-gas (argon) atmosphere leads to an increase in the microhardness of the surface layer and a decrease in the surface roughness of the irradiated samples by a factor of five in comparison with the roughness of the original samples.     

Specific features of the welding of metals by radiation of high-power fiber laser

The properties of the plasma that results from the laser welding of metals at various powers of the 10-kW ytterbium-doped fiber laser are experimentally studied. A projection system with an image intensifier based on a copper-vapor laser is employed for the direct observation of metal surface in the course of the laser welding in the presence of the high-intensity background illumination. A method for the shadow photographing is proposed for the analysis of the presence of metal vapor in plasma, since such vapor can lead to the reflection of the laser radiation in the course of welding.     

Study of Mechanical Characteristics of Stainless Steel Samples Obtained by Direct Laser Deposition

Physics of Atomic Nuclei - The paper presents the results of mechanical tensile tests and microhardness of samples obtained from stainless steel 316L powder by direct laser deposition. The strength...     

Spectral diagnostics of a vapor-plasma plume produced during welding with a high-power ytterbium fiber laser

We have conducted spectroscopic studies of the welding plasma formed in the process of welding with an ytterbium fiber laser delivering output power of up to 20 kW. The influence of shielding gases (Ar, He) on different parts of the welding plume is investigated. The absorption coefficient of the laser radiation by the welding-plume plasma is estimated. Scattering of 532-nm probe radiation from particles of the condensed metal vapor within the caustic of a high-power fiber laser beam is measured. Based on the obtained results, conclusions are made on the influence of the plasma formation and metal vapor condensation on the radiation of the high-power fiber laser and the stability of the welding process.     

Tunable laser diodes for the 1250-1650 nm spectral range

A series of tunable laser diodes was developed with emission wavelength in spectral range 1250-1650 nm. This paper describes the configuration and basic characteristics at temperatures from 5 to 80 degrees C.     

Oxidation of alkanes and alcohols with hydrogen peroxide catalyzed by complex Os3(CO)10(µ‐H)2

Trinuclear carbonyl hydride cluster, Os₃(CO)₁₀(µ‐H)₂, catalyzes oxidation of cyclooctane to cyclooctyl hydroperoxide by hydrogen peroxide in acetonitrile solution. The hydroperoxide partly decomposes in the course of the reaction to afford cyclooctanone and cyclooctanol. Selectivity parameters obtained in oxidations of various linear and branched alkanes as well as kinetic features of the reaction indicated that the alkane oxidation occurs with the participation of hydroxyl radicals. A similar mechanism operates in transformation of benzene into phenol and styrene into benzaldehyde. The system also oxidizes 1‐phenylethanol to acetophenone. The kinetic study led to a conclusion that oxidation of alcohols does not involve hydroxyl radicals as main oxidizing species and apparently proceeds with the participation of osmyl species, ‘Os?O’. Copyright © 2010 John Wiley & Sons, Ltd.