Evolution of triple junction defect structure at plastic deformation of metallic polycrystals

A method for the determination of the components of the Frank vector of disclinations in triple junctions (TJ) of real polycrystalline aggregates has been proposed. Using this method we found that real polycrystals contain junction disclinations (JD), the nature of which is related to their thermo-mechanical history. One of the elements of the evolution of the network of initial junction disclinations is the formation of disclination dipole configurations in the adjacent TJ. The influence of the types of boundaries forming the junctions on JD Frank vector power is discussed.     

The Formation and Structure of Thermomigration Silicon Channels Doped with Ga

Technical Physics - Vertical through Si(Ga) p channels are created at 1450 K in c-Si(111) plates by thermomigration of local gallium zones. To this end, a technique is proposed and implemented for...     

Two-phase filtration of multicomponent mixtures with a retrograde region of the phase diagram

The results of mathematical and physical modeling of an isothermal filtration of multicomponent mixtures with a retrograde region of the phase diagram are presented. By the example of mixtures of hydrocarbons of the methane line, the conditions at which the hydrocarbon-two-phase fluid?porous space system is a self-oscillation system are determined. The data obtained make it possible to explain certain regularities of the filtration of gas-condensate mixtures and can be used to increase the extraction of gas-condensate deposits.     

Inversion of configuration in the closed form of spirothiopyran molecules

Conclusions The Gvalue for the inversion of configuration of the closed form of spirothiopyrans is significantly greater than for their oxygen analogs due to steric hindrance for rotation of the rotation of the benzopyran fragment relative to the indoline fragment.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1666–1668, July, 1987.     

Disclination Mechanism of Plastic Deformation of Nanocrystalline Materials

A model describing mechanical behaviour of nanocrystalline materials (NC) obtained by crystallization from amorphous precursor is presented. In the framework of this model a structure of such NCs is represented as a composite consisting of amorphous matrix and absolutely rigid inclusions corresponding to crystalline phase. Dependencies of stress concentration coefficient and yield stress of NCs on the average grain size are obtained. It is shown that the dependence of the yield stress has a point of inflection at the critical grain size in the range of 20–25 nm and is inverse to the Hall-Petch relationship at grain sizes smaller than the critical one. The model predicts a formation of a superlattice from disclinations located in triple junctions of grains on the stage of NC plastic flow. A process of the plastic flow of NC's amorphous matrix and amorphous metallic alloys is described as a go-ahead mechanism of dislocation movement, which includes emission, absorption and reemission of dislocations by disclinations.     

Synthesis of triarylimidazole hybrid compound with switchable luminescence

A novel hybrid compound composed of substituted imidazole and salicylideneaniline luminophors has been synthesized and shown to exhibit multiple luminescence in ethanol, which can be switched by varying the excitation wavelength.     

Nature of nanocrystallization in shear bands created by megaplastic deformation in amorphous alloys

A theoretical study is made of the process of nanocrystallization upon the formation of shear bands created by megaplastic deformation in amorphous metallic alloys. Such nanocrystallization is shown to be caused by a considerable increase in temperature inside the shear bands, which in turn is associated with the stored energy of megaplastic deformation. The temperature increment depends on the degree of deformation, the rate of propagation of the shear band, and the physical parameters that determine the thermal characteristics of an amorphous matrix in the range of the shear band.     

Spectral and luminescent properties of hydroxyazomethines of indoline spiropyrans

Spectral and luminescent properties of novel bifunctional compounds 1–3 based on indole spiropyrans and hydroxyazomethines have been studied in comparison with the properties of the model compounds 5’-substituted spiropyrans and azomethines in organic solvents and PMMA films at 293 and 77 K. Luminescence of compounds 1–3 is due to the presence of the azomethine fragment conjugated with the indoline ring of the spiropyran moiety and determining the long-wavelength absorption band of 1–3. Depending on the solvent, temperature, and the substituent, various combinations of the structures of the chromophore fragments are observed in 1–3: the imine or amine form of the azomethine fragment and the spirocyclic or merocyanine form of the spiropyran fragment.