Identification of the convective instability in a multi-component solution by 3D simulations

Three-dimensional calculations have been done to simulate the onset of convective motion in ternary nondilute solution under phase transition conditions. The process is considered for Rayleigh number in the range $[1\times {10}^3,1.4\times {10}^4]$, where subcritical convective motion with hexagonal flow pattern is identified. The results are in good agreement with the linear and finite amplitude theory of hydrodynamics instability. To cite this article: V.V. Kolmychkov et al., C. R. Mecanique 333 (2005).     

Numerical investigation of liquid electrophoresis without support media

Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 14–20, May–June, 1988.     

Two Equivalent Finite Volume Schemes for Stefan Problem on Boundary-Fitted Grids: Front-Tracking and Front-Fixing Techniques

Differential Equations - We present finite-difference schemes on boundary-fitted grids for the two-dimensional Stefan problem. It is shown that the proposed numerical schemes constructed by...     

Investigation of the transformation of the spectrum of femtosecond laser radiation on filamentation in gas medium

The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) in a filament on the distance along the filament propagation axis, the diaphragm diameter, and the type and pressure of gas used for filamentation has been studied experimentally.     

3D Raman bullet formed under filamentation of femtosecond laser pulses in air and nitrogen

Complex experimental study of spectral, spatial and temporal behaviors of the IR shifted component observed under filamentation of the collimated femtosecond laser beam (80 GW, 50 fs, 805 nm) in molecular gases showed that this component behaves like a Raman soliton. Namely, it is confined in all domains: (a) it propagates within the filament core, (b) it has a stable duration of 30 fs along the filament, and (c) its spectrum shifts as a whole from 820 to 870 nm on the distance of 2 m from the filament start. A simple model explaining the origin of anomalous group velocity dispersion in the plasma channel of a filament is suggested.     

Algorithm for solving the Navier–Stokes equations for the modeling of creeping flows

We study a coupled algorithm for solving the two-dimensional Navier–Stokes equations in the stream function–vorticity variables. The algorithm is based on a finite-difference scheme in which the inertial terms in the vortex transport equation are taken from the lower time layer and the dissipative terms, from the upper time layer. In the linear approximation, we study the stability of this algorithm and use test computations to show its advantages when modeling flows at moderate Reynolds numbers.     

Optimization of a femtosecond pulse self-compression region along a filament in air

We have identified the pulse self-compression region in a filament produced by 55 fs, 4 mJ, 805 nm radiation propagating in air without geometrical focusing. In our experiment the pulse self-compression region is attained by the propagation distance, where the shortest wavelength in the supercontinuum blue wing reaches a minimum, and the growing conversion efficiency to white light has a large gradient. Numerical tracking of the pulse along the filament shows a single-peak 9 fs pulse with a flat spectral phase at the optimum compression distance. PACS 42.65.Jx; 42.65.Re; 42.65.Ky     

Improvement of quality of carbon fiber rods by the impregnation of carbon fibers with oligoorganosiloxanes

Russian Chemical Bulletin - The effect of the impregnation of the UKN-M-6K carbon fiber with organosilicon binders on the characteristics of carbon fiber rods was studied. Solutions of...     

Enzymatic oxidation of cadmium and lead metals photodeposited on cadmium sulfide

Cadmium and lead metals deposited on CdS particles are shown to act as substrates--electron donors for enzymes, hydrogenase from Thiocapsa roseopersicina (HG), NAD-dependent hydrogenase from Alcaligenes eutrophus (NLH), and ferredoxin:NADP oxidoreductase (FNR) from Chlorella in the formation of hydrogen, NADH and NADPH, respectively. Adsorption of the enzyme on the surface of the metallized CdS particle is required for enzymatic oxidation of metal. The maximum rates for the formation of hydrogen and NADH catalyzed by hydrogenase and NAD-dependent hydrogenase with metals as electron donors are comparable with the rates obtained for these enzymes using soluble substrates. Kinetic analysis of the enzymatic oxidation of cadmium metal has revealed that the rate decreases mainly due to the formation of a solid product, which is supposed to be Cd(OH)2. The deceleration of lead oxidation catalyzed by hydrogenase proceeds at the expense of the inhibitory effect of the formed Pb2+. The enzymatic oxidation of electrochemically prepared cadmium metal is also shown. Based on these results, a new mechanism of action of the enzymes involved in anaerobic biocorrosion is proposed. By this mechanism, the enzyme accelerates the process of metal dissolution through a mediatorless catalysis of the reduction of the enzyme substrate.