Application of Synchrotron Radiation to Analyze the Friction-Induced Structural and Phase Transformations of Chrome-Nickel Austenitic Steel

Russian Physics Journal -     

The Generating Function for the Components of the Euler–Poinsot Tensor

Doklady Physics - Generating functions that enable us to calculate the components of the Euler–Poinsot tensor using differentiation are introduced. The role of these functions is similar to...     

Reconstruction of the blood flow velocity vector as an additional mode of ultrasonic tomograph

The possibility of simultaneous reconstruction of the blood flow velocity vector and spatial distributions of the speed of sound and absorption coefficient in a medical ultrasonic tomograph is discussed. The operating capacity of the proposed spatial-correlation method for determining the blood flow velocity vector is confirmed by experiments on a tomograph prototype.     

Study of polyol synthesis reaction parameters controlling high yield of silver nanocubes

The influence of the parameters and conditions of sodium sulfide-induced reaction of polyol synthesis of silver nanoparticles on the yield of cube-shaped particles and the optical properties of colloids is studied. The protocol proposed by Skrabalak et al. for the synthesis of nanocubes in small volumes (Nature Protocols, 2007, vol. 2, p. 2182) is taken as an initial variant for optimization. The effects of the reagent concentrations, degree of ethylene glycol oxygenation, the presence of impurities, reaction time, and temperature are studied. Suspensions containing nanoparticles with different shapes and sizes, including polydisperse particles of irregular shapes, silver nanocubes with a yield of 0 to 97%, nanoprisms, and nanorods, can be produced by varying the synthesis parameters. The key parameters controlling the yield of nanocubes are the degree of ethylene glycol oxygenation and the presence of trace amounts of ions of other metals (not silver). It is established that variations in the reaction time make it possible to vary the sizes of nanocubes in the range of 30–60 nm. Suspensions with high contents of cube-shaped particles are shown to exhibit three maxima in the plasmon extinction resonance spectrum at wavelengths of 350, 390, and, depending on the particle size, 435–470 nm.     

Effect of diffusion and fluctuations in the nonequilibrium charge carrier density on the angular distribution of the output intensity for injection lasers based on an InAsSb/InAsSbP heterostructure

We have used numerical modeling to study the effect of diffusion and fluctuations in the nonequilibrium carrier density in the active layer of injection lasers based on an InAsSb/InAsSbP heterostructure on the angular distribution of the output intensity. We show that diffusion smoothes out the nonequilibrium carrier distribution in the active layer, and the fundamental lasing mode is stable over a much broader range of stripe contact widths. At the same time, diffusional processes can lead to formation of local regions with a jump in the density of nonequilibrium charge carriers, fluctuations in which can act as a source of instability for the fundamental lasing mode. Analysis of the numerical modeling results gives qualitative agreement with experimental data on the dependence of the angular distribution of the output radiation for different stripe contact widths.     

Oxidative alkylamination of 2-methyl-3(2H)-cinnolinone: unexpected dealkylation of the entering alkylamino group

The oxidative alkylamination of 2-methyl-3(2H)-cinnolinone by secondary alkylamines in the presence of KMnO₄ leads to the smooth formation of the expected 4-alkylamino-2-methyl-3(2H)-cinnolinones. The analogous reaction with primary alkylamines is accompanied by the partial or complete N-dealkylation of the entering alkylamino group depending on the temperature. *Dedicated with gratitude to an outstanding heterocyclic chemist, Prof. Henk van der Plas on the occasion of his eightieth jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 602-611, April, 2009.