Suppression of magnetic relaxation by a transverse alternating magnetic field

The evolution of the spatial distribution of the magnetic induction in a superconductor after the action of the alternating magnetic field perpendicular to the trapped magnetic flux has been analyzed. The observed stabilization of the magnetic induction profile is attributed to the increase in the pinning force, so that the screening current density becomes subcritical. The last statement is corroborated by direct measurements.     

A study of spiro[indoline-pyridobenzopyrans] by differential pulse voltammetry on a dropping mercury electrode and quantum chemistry

Spiropyrans of the indoline series were studied by differential pulse voltammetry in DMSO solutions. The experimental data obtained were supported by quantum-chemical calculations performed to examine the structural features and thermodynamic stability of a series of spiro-pyrans. The calculations revealed a correlation between the peak potential (E _p) of spiropyrans and the energy of the lowest unoccupied π orbital. Procedures were developed for identification and quantitative determination of all the spiropyrans in DMSO on a mercury dropping electrode in the concentration range from 1 × 10^?7 to 1 × 10^?6 M.     

Photochromic properties of phenanthroline-annulated spirooxazine in the solid state

Photochromic transformations of phenanthroline-annulated spirooxazine were observed in polycrystalline powders and solid-phase films obtained from solutions by solvent evaporation. The spectral and kinetic properties of the solid-phase films were studied by stationary absorption spectroscopy and laser flash photolysis. The mechanism of photoinitiated reactions of solid-phase samples of phenanthroline-annulated spirooxazine includes mutual transformations of different transoid isomers of the merocyanine form.     

Peculiarities of the diffraction contrast in plane-wave X-ray topographs of weakly deformed crystals in the bragg geometry

The regularities of the topographic contrast formation in weakly deformed nonabsorbing crystals in the Bragg geometry for the diffraction of a plane X-ray wave have been investigated by the method of Riemann functions. It is shown that in this case the extinction contrast has an interference character, alternates, and is proportional to the strain gradient rather than to the squared strain (like in the case of strong lattice distortions). The data of the analysis are compared with the results of a model numerical experiment. The possibility of implementing an X-ray-acoustic resonance in the Bragg geometry is shown.     

Study of the multilayer PCB CTEs by moiré interferometry

Microelectronics packaging has been developing rapidly due to the demands for faster, lighter and smaller products. Printed circuit boards (PCBs) provide mechanical support and electrical interconnection for electronic devices. Many types of composite PCBs have been developed to meet various needs. Recent trends in reliability analysis of PCBs have involved development of the structural integrity models for predicting lifetime under thermal environmental exposure; however the theoretical models need verification by the experiment.

The objective of the current work is the development of an optical system and testing procedure for evaluation of the thermal deformation of PCBs in the wide temperature range. Due to the special requirements of the specimen and test condition, the existing technologies and setups were updated and modified. The discussions on optical methods, thermal loading chambers, and image data processing are presented. The proposed technique and specially designed test bench were employed successfully to measure the thermal deformations of PCB in the −40°C to +160°C temperature range. The video-based moiré interferometry was used for generating, capturing and analysis of the fringe patterns. The obtained information yields the needed coefficients of thermal expansion (CTE) for tested PCBs.     

Chemiluminescence of the 9,10-anthrasemiquinone radical ion during autooxidation of 9,10-dibromoanthracene in the diphenylmethane-ButOK-DMSO system

Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 189–190, January, 1995.     

Ribbed-monofunctionalized iron(II) clathrochelate with tert-butyl sulfide substituents: Synthesis,structure, and thermochemical transformations

A ribbed-monofunctionalized macrobicyclic iron(II) complex with tert-butyl sulfide substituents has been prepared via nucleophilic substitution of its dichloroclathrochelate precursor with tert-butylthiolate ion. This new complex has been characterized using elemental analysis, IR and multinuclear NMR spectroscopy, and the single crystal X-ray diffraction. Its thermal destruction occurs with release of isobutylene and polyunsaturated hydrocarbons giving iron borate, iron fluoropolyborate, and iron nitride as follows from combined thermal analysis and X-ray powder diffraction data.