Polarizable molecular interactions in condensed phase and their equivalent nonpolarizable models

Earlier, using phenomenological approach, we showed that in some cases polarizable models of condensed phase systems can be reduced to nonpolarizable equivalent models with scaled charges. Examples of such systems include ionic liquids, TIPnP-type models of water, protein force fields, and others, where interactions and dynamics of inherently polarizable species can be accurately described by nonpolarizable models. To describe electrostatic interactions, the effective charges of simple ionic liquids are obtained by scaling the actual charges of ions by a factor of 1/sqrt(eps_el), which is due to electronic polarization screening effect; the scaling factor of neutral species is more complicated. Here, using several theoretical models, we examine how exactly the scaling factors appear in theory, and how, and under what conditions, polarizable Hamiltonians are reduced to nonpolarizable ones. These models allow one to trace the origin of the scaling factors, determine their values, and obtain important insights on the nature of polarizable interactions in condensed matter systems.Comment: 43 pages, 3 figure

Metal Phase Formation in Bubbling Reduction of Nickel and Iron from Oxide Melt

Bubbling reduction of nickel and iron from oxide melt is considered. Oxidized nickel ores melts interaction with gases (hydrogen, carbon monoxide, converted natural gas) is accompanied by the ferroalloy formation with high nickel content. This process is associated with the mass transfer, chemical reaction running and metal phase formation in the multi-component oxide melts, regardless of the reducing agent used. Those processes are of great importance for understanding of the ferronickel pyrometallurgical production processes. To describe the process, we used equations that allow one to estimate the size of gas bubble and metal drop moving in an oxide melt without fragmentation, its joint movement direction, flotation rate, sedimentation and separation conditions. The physicochemical characteristics affecting mass transfer (the densities and surface tensions of oxide and metal melts, as well as their interfacial characteristics) have been determined. Keywords: nickel, iron, reduction, bubbling, metal, oxide, melts, ores, ferroalloy, flotation, sedimentation, reducing ga

Structural, electronic and optical properties of heterointerfaces based on antiferromagnet LaMnO3 and ferroelectrics isostructural to BaTiO3

The reported study was funded by Russian Scientific Foundation according to the research project No. 18-12-00260

Quasi-two-dimensional electron system at the interface between antiferromagnet LaMnO3 and ferroelectric Ba0.8Sr0.2TiO3

The reported study was funded by Russian Scientific Foundation according to the research project No. 18-12-00260

Ultrafast spectroscopy of CdS/CdSe quantum dots

© 2017, Allerton Press, Inc. Results from the nonresonance spectroscopy of CdS/CdSe quantum dots (composites of CdSe–CdS nanoparticles (core–shell)) are presented. The nonlinear optical properties of CdS/CdSe QDs in PMMA are studied with fs pulses at 1053 nm using the transient lens technique. QDs generate rapidly oscillating signals with amplitude rise times of around 200 fs and decay times of around 500 fs, while pure PMMA polymer only generates an oscillating signal whose envelope coincides with its autocorrelation function

Electron dynamics at GaAs-AlGaAs heterojunction studied by ultrafast spectroscopy

In this letter the electron and spin dynamics at GaAs/AlGaAs heterojunction was studied by ultrafast spectroscopy techniques (photon echo and transient grating studies). Relaxation times and diffusion coefficients of photoexcited electrons and spins were obtained using pure optical setup. The estimated spin diffusion coefficient value of 160 cm2/s is relatively high and comparable to the electron diffusion coefficient of 200 cm2/s. This feature makes GaAs/AlGaAs heterosructure a promising material for practical application in semiconductor spintronics. © Published under licence by IOP Publishing Ltd

Новая парадигма решения задачи радиолокационного обнаружения пленок нефти при скользящих углах облучения поверхности моря

Low efficiency of using of commercially available marine navigation radars to detect the oil slicks on the sea surface is showed. A new approach to the problem of oil films detection on the sea sur-face by radar at low grazing angles of irradiation is discussed. It's proposed to develop specialized radar, a list of tasks necessary for the creation such radar is formulated.Показана низкая эффективность использования серийно выпускаемых судовых навигационных радиолокационных станций (РЛС) для обнаружения пленок нефти на поверхности моря. Обсужден новый подход к постановке проблемы обнаружения пленок нефти на поверхности моря с помощью РЛС при скользящих углах облучения. Предложено разработать специализированные РЛС; сформулирован перечень задач, решение которых необходимо для создания таких РЛС

Особенности построения нейронной сети в робастной радиолокационной системе классификациимономолекулярных пленок нефти на поверхности моря при горизонтальной поляризации электромагнитного поля

Neural network that allows to make a decision about the presence or absence of monomolecular films of medium or heavy oil on the sea surface in the radar with horizontal polarization, integrated into a single system with passive reflectors located either on the perimeter of the port basin, or on special buoys at sea is proposed.Предложена нейронная сеть, позволяющая принять решение о наличии или об отсутствии мономолекулярных пленок средней или тяжелой нефти на поверхности моря. Решение принимается в результате обработки сигнала радиолокационной станции с горизонтальной поляризацией электромагнитной волны, объединенной в единый комплекс с пассивными отражателями, расположенными по периметру акватории порта, а также на специальных буях в море