Reconstruction of a complex-shaped defect from the known arrival time of the reflected ultrasonic wave

The problem of reconstructing the boundary of an arbitrarily shaped defect formed inside an elastic body from the measured time of arrival of the reflected ultrasonic wave in the echo method is considered. The characteristic size of the defect is assumed to be greater than the wavelength, and the defect is irradiated from the far-field zone, which means that the incident wave can be considered as plane. An algorithm is developed for reconstructing the convex envelope of a nonconvex defect from the arrival times of echo signals measured at different angles with the use of circular scanning.     

Synthesis and properties of 1,2,3-triazoles that contain a ferrocenyl ring

Ferrocenesulfonyl azide reacts with a number of aroylmethylenetriphenylphosphinomethylenes in dry methylene chloride to give 1,4,5-trisubstituted 1,2,3-triazoles (61–77% yields), which are readily converted to 4,5-disubstituted 1,2,3-triazoles and ethyl ferrocenesulfonate when they are refluxed in ethanol. The known tri-phenylphosphazo ferrocenyl sulfone and ethyl diazoacetate are formed in the case of the reaction of ferrocenesulfonyl azide with carbethoxymethylenetriphenylphosphinomethylene. The structures of the synthesized compounds were proved by the results of elementary analysis and IR, UV, and mass spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 701–704, May, 1980.     

Inversion of the total current in dielectrics bombarded with charged particles

We report and discuss the results of studies on the reversal of the total current in dielectrics bombarded with charged particles (electrons, protons, deuterons, and alpha particles) with ranges shorter than the thickness of the samples. The results are explained by the time dependence of the radiation conductivity.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 121–125, October, 1991.     

The synthesis and structure of ferrocenylalkyl onium derivatives of nitrogen-containing heterocyclic compounds

The reactions of hydroxymethylferrocene, -hydroxyethylferrocene, and 1,1-bis(-hydroxyethyl)ferrocene withN-ferrocenylalkyl-substituted benzotriazoles, hexamethylenetetramine, and azaferrocene in the CH₂Cl₂ — 48% aqueous HBF₄ two-phase system affordedN-mono-,N-1,1-ferrocenylene-bis--alkylated, and 1,3-bis-ferrocenylalkylated tetrafluoroborates of the above-mentioned heterocyclic compounds in high yields. An X-ray structural study of 1,3-bis-(ferrocenylmethyl)benzotriazolium tetrafluoroborate confirmed unambiguously the 1,3-arrangement of the ferrocenylmethyl groups in the heterocycle.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 554–558, March, 1995.     

Spectroscopic studies of (AsSe)100−xAgx thin films

Thin (AsSe)_100−xAg_x films have been grown onto quartz substrates by vacuum thermal evaporation or pulsed laser deposition from the corresponding bulk materials. The amorphous character of the coatings was confirmed by X-ray diffraction investigations. Their transmission was measured within the wavelength range 400-2500 nm and the obtained spectra were analyzed by the Swanepoel method to derive the optical band gap E_g and the refractive index n. We found that both parameters are strongly influenced by the addition of silver to the glassy matrix: E_g decreases while n increases with Ag content. These variations are discussed in terms of the changes in the atomic and electronic structure of the materials as a result of silver incorporation.     

Oscillations of a bubble separated from an air cavity under compression caused by magnetic field in a magnetic fluid

Based on the concept of mapping the free surface geometry of a weakly magnetic medium by the topography of isolines of the magnetic field strength magnitude, the shape of the free surface of a magnetic fluid is studied in the static state at two stages: the initial stage, where an annular magnet is moving toward the surface of the magnetic fluid column in a tube, and at the stage where the air cavity is pressed to the bottom. It is shown that the separation of bubbles from the air cavity occurs at the magnet axis in the immediate vicinity of the magnet symmetry plane. A method and an experimental setup are proposed to investigate possible electromagnetic indication of the size of air bubbles formed in the magnetic fluid. The results of an experimental study of bubble separation from an air cavity held in the magnetic fluid and compressed by the pondermotive forces of the magnetic field are discussed. The results may be of importance for designing a new technique for metering small gas shots to a reactor.