Photosensitive molecular tweezers 3. Synthesis and homoditopic complex formation of a bisstyryl dye containing two crown-ether fragments with diammonium salts

A new molecular tweezers, viz., bisstyryl dye containing two 18-crown-6-ether moieties and one p-phenylenedimethylene spacer group, was synthesized. Complex formation of this dye and a model monostyryl dye with ions EtNH₃ ⁺ and NH₃ ⁺(CH₂)_nNH₃ ⁺ (n = 2−6) in MeCN was studied using spectrophotometry and ¹H NMR spectroscopy. The homoditopic bisstyryl dye and diammonium salts form strong supramolecular complexes with pseudocyclic structure.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 656–662, March, 2005.     

Features of electrical explosion alloying of metals and alloys

The kinetics of the electrical explosion of foils has been investigated and the parameters of the plasma jet, the radius of the plasma-affected zone, the pressure and temperature of the plasma in the shock-compressed layer near the irradiated surface, and the accepted power density at the jet axis have been calculated in relation to the dimensions of the plasma accelerator, the distance from the nozzle exit section to the irradiated surface, and the charge voltage of the energy store. Modes of electrical explosion alloying of metals have been determined experimentally which are associated with surface melting, splashing of melt, effects of convective heat and mass transfer, aftereffect, and also with physicochemical and physicomechanical features of the materials used. Methods of optical, scanning, and transmission electron diffraction microscopy have been used to examine the relief, phase composition, and defect substructure of the surface layers of metals after various types of one-and two-component electrical explosion alloying. A multilayer structure has been revealed which is characterized by the degree of variation of the phase-structure state and of the material mechanical characteristics. Based on the features of the multiphase jet that serves as a tool for affecting the surface, some propositions have been made on the physical nature of the processes occurring in a material subject to electrical explosion alloying. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 71–83, May, 2008.     

Electron Diffraction Analysis of the Fracture Zone of Fe–0.45C–17Mn–3Al Steel Subjected to Multicyclic Fatigue Tests

The methods of transmission electron microscopy are used to investigate the structure and phase content of Fe–0.45C–17Mn–3Al steel subjected to multicyclic fatigue tests to failure after intermediate electrostimulation. It is demonstrated that electrostimulation does not change the mechanism of steel failure. An increase in the operating life time of samples after electrostimulation in the intermediate test stage is connected with the hindered -martensitic transformation, the relaxation of stress concentrators, and the reduction of the volume fraction of the critical dislocation (network) substructure in which -martensite is mainly developed.