Voronezh State University

About: Voronezh State University is a education organization based out in Voronezh, Russia. It is known for research contribution in the topics: Silicon & Boundary value problem. The organization has 5166 authors who have published 6097 publications receiving 31680 citations. The organization is also known as: VSU & Voronezh University.

Expedited Transition in the Wettability Response of Metal Meshes Structured by Femtosecond Laser Pulses for Oil-Water Separation.

Abstract: Oil-water separation by super-wetting and selective permeability of membranes for oil or water has great ecological and economic significance. We report on the transition of wettability response, from superhydrophilic underwater-superoleophobic to superhydrophobic-superoleophilic, by nanostructuring stainless steel and copper meshes using ultrashort femtosecond laser pulses. Our approach is environment-friendly, chemical free and, and efficient as it exploits the benefit of aging the processed samples in high vacuum environment. We optimized the laser scanning parameters, mesh pore size and ageing conditions to produce membrane exhibiting extraordinary separation efficiency of 98% for oil-water mixture. A variation in the water and oil contact angles for different meshes is presented as a function of laser scanning speed. Stainless steel meshes with 150 µm pore size and copper mesh with 100 µm pore size have demonstrated excellent wettability response for oil and water phases. Vacuum ageing causes rapid chemisorption of hydrocarbons on laser structured surface in the absence of water molecules, rapidly transforming the wetting state from superhydrophilic underwater-superoleophobic to superhydrophobic-superoleophilic state.

Frequency shifts of sound field maxima in few-mode propagation, which are initiated by internal wave solitons

Abstract: The problem of frequency shifts of sound field interference maxima, which are due to the motion of internal wave solitons in the ocean medium and cause intermodal transformation effects, has been solved for few-mode propagation regime. Simulation results are presented and the conditions of applicability of the adiabatic approximation, in which normal waves can be considered as independent, are discussed. The numerical experiment data are used to analyze the possibility of reconstructing the soliton parameters by measuring the frequency shifts of wave field maxima.

Effect of helium-neon laser on activity and optical properties of catalase.

Abstract: The effects of laser (632.8 nm) on functional and spectral properties of catalase at pH 6.0-7.4 were studied. Laser irradiation led to photoactivation of the enzyme at pH 7.1-7.4. Changes in the spectral properties of photomodified hemoprotein were found in the absorption spectrum of the protein component: apoenzyme displayed protective effects in relation to ferroporphyrin. Structural modifications of catalase induced by helium-neon laser irradiation correlated with its functional properties. These results can be used in clinical practice to design the individual management program.

Estimation of the number of orthogonal signals with unknown non-energy parameters

Abstract: The synthesis and analysis of an algorithm for estimation of the number of orthogonal signals with unknown non-energy parameters have been performed by using the maximum likelihood method.