In modern research, symbolic regression is a powerful tool for constructing mathematical models of various systems. In this paper, three symbolic regression methods are applied and compared: genetic programming, sparse identification of nonlinear dynamics and hybrid method. The performance of each method is evaluated by its ability to find accurate models with high accuracy and low complexity in the presence of varying levels of noise in the observational data. Based on the results of the experiments, it was concluded that the best method for identifying dynamic systems is the hybrid method, which combines genetic programming and sparse identification

Keywords: symbolic regression,identification of dynamical systems,genetic programming, sparse identification of nonlinear dynamics, hybrid method GP-SINDy

In this article is reviewed the nature of organic hybrid nanocomposites. Promising directions in the field of organic hybrid nanocomposite materials will be methods for the synthesis of multicomponent materials, as well as the type of "net net" and "host-guest". The fundamental problem with the chemistry and physics of nanocomposites is dependent "structure-property". Solving this problem will move from research materials to their purposeful design.

Keywords: nanocomposite sol-gel technology, synthesis, nanoparticles.

The composite cathode material of the core@shell type with the LiMn2O4@LiCoO2 formula of has been successfully synthesized using the solid-state reactions in several stages. Its structure has been studied by means of X-ray diffraction, scanning and transmission electron microscopy and vibrational infrared spectroscopy. Electrochemical investigation in two-electrode cell has been showed improvement of characteristics of the synthesized cathode material than the constituent components. The specific power of LiMn2O4@LiCoO2 is 650 mWh/g, against 450 and 500 mWh/g for LiCoO2 and LiMn2O4, respectively.

Keywords: lithium-ion batteries, cathode materials, Delafosse, X-ray structural analysis, electron microscopy, electrochemical properties

Fe-doped AlN nanorods were studied by means of x-ray absorption spectroscopy above the Fe K- and L2,3- edges. Theoretical simulations of the x-ray absorption spectra show that Fe atoms mainly substitute Al. A minor fraction of Fe interstitials or Fe-Al-N ternary alloy can be identified as well. Bader’s AIM analysis predicts that neutral substitutional FeAl defect is in 2+ charge state, though Al in pure AlN is in 3+ charge state.  Fe L2,3 absorption spectra and photoluminescence data indicate the coexistence of Fe2+/Fe3+ in AlN:Fe nanorods so different charge states of substitutional FeAl should co-exist.

Keywords: diversification of management, production diversification, financial and economic purposes of a diversification, technological purposes of ensuring flexibility of production

The catalytic activity of Pt/C and PtxNi/C electrocatalysts prepared by  borohydride methode was studed. It was established that the specific activity  of fresh prepared Pt3,7Ni/C  catalyst  in oxygen  electroreduction  reaction is higher in compare with Pt/C material. After treatment of Pt3,7Ni/C material in the hot acid  nickel in the surface layers of nanoparticles was dissolved and the composition of nanoparticles was changed to Pt5,6Ni. The electrochemical surface area of the Pt5,6Ni catalyst and specific activity was slightly decreased after corrosion treatment. 

Keywords: platinum electrocatalysts, corrosion stability of the nanoparticles, fuel cells, X-ray diffraction, borohydride synthesis

With the use of pulsed laser deposition and carbothermal synthesis а photosensitive structure on the basis of the Schottky barrier Au/ZnO(nanorods)/ZnO(film)/ZnO(nanorods)/Au was obtained. The parameters of the carbothermal method of synthesis of nanorods ZnO were optimized. Under directly applied bias of 7V current sensitivity of luminous flux for this photodetector is observed in the UV and visible regions of the spectrum, and is 0.14 A/W - for 325 nm and 0.18 A/W - to 405 nm, which means that this structure has the ability of potential applications in various fields for the control of UV radiation (for example, for the monitoring of solar UV radiation, control of UV radiation in air and disinfecting water devices).

Keywords: ZnO nanorods, Schottky barrier, photodetector, photosensitivity

ZnO nanorod arrays have been synthesized on silicon wafers by chemical vapor deposition (CVD) technique with different  temperature modes, without metal catalyst.  With this method   vertically aligned ZnO nanostructures  were grown at the quite low temperatures.  Modification of the method allowed to place silicon substrates in areas with different  ratios of concentrations of the molecules in the vapor phase. Photoluminescence spectroscopy and electron microscopy studies have shown that morphologies and optical properties of nanorods depends on different ratios of concentrations of the molecules in the vapor phase.

Keywords: ZnO nanorods,chemical vapor deposition (CVD), photoluminescence

The arrays of ZnO nanorods were obtained on the sapphire substrates by means of pulsed laser deposition under the high pressure of argon. The conditions of synthesis were optimized, and their influence on the morphology of  ZnO nanostructures were revealed. It is shown that the concentration of oxygen vacancies in ZnO nanorods can be changed by regulation of the synthesis temperature from 850 to 915 °. This process can be controlled by the ratio of intensities of the photoluminescence emission in the visible and ultraviolet regions. So, it allows to create nanostructures for UV photodetectors or chemosensors depending on the temperature choice.

Keywords: ZnO nanorods, laser deposition, PLD, photoluminescence

Одним из важнейших факторов, исключающих возникновение дефектов типа пор, расслоений, участков с неполной полимеризацией связующего в формуемой высоконагруженной полимерной композитной конструкции, является управляемость процесса во всем объеме композита. Для обеспечения однородности процесса полимеризации связующего предложен метод многокритериальной оптимизации процесса на основе математической модели, связывающей процессы распространения тепла и кинетики полимеризации. Система связанных уравнений процесса, учитывающая экзотермическое тепло, выделяемое при полимеризации термореактивного связующего, изменение теплоемкости и теплопроводности композита при фазовых переходах от жидкого к гелеобразному и, далее, к твердому состоянию, точную геометрию технологической системы, включая прессформу, а также интенсивность тепловыделения независимо управляемых нагревателей, реализована в виде конечноэлементной модели. Предложенный метод синтеза закона оптимального управления нагревателями, использующий метод множеств Парето, проиллюстрирован на примере полимеризации разностенной композитной конструкции, формуемой из стеклопластика.

Keywords: Композиционные материалы; Процесс полимеризации; Оптимальное управление; Кинетические уравнения; Уравнения в частных производных в задачах управления и оптимизации, Конечно-элементное моделирование, Фронт Парето

In this work we have investigated the structure of individual single-walled and multi-walled carbon nanotubes by high-resolution electron microscopy and electron diffraction. To grow carbon nanotubes we used a catalytic chemical vapor deposition method. It was shown, that this synthesis protocol gave in general single-walled and double-walled carbon nanotubes with a high level of crystallinity. The diameters of the nanotubes were in the range 1.5 - 7 nm. We also observed that there was a certain level of amorphous carbon deposited on the nanotube surface during the growth. In this work we also present the structure analysis of the double-walled carbon nanotube by means of electron diffraction. We show that the structural date derived from electron microscopy and electron diffraction agree within the experimental error.

Keywords: Carbon nanotubes, electron diffraction, electron microscopy

In this paper we propose basic geometric, mass and electrical parameters of the element for collection of static electricity from the surface of the textile. This element is a reversible electrochemical charge storage system based on nanostructured nickel oxide and carbon cloth. Element has a planar structure, it is flexible, lightweight, safety and ergonomic. Proposed element can be used as a power source for the Microsystems technique in "smart clothes".

Keywords: "smart clothes", microsystems technique, static electricity, supercapacitor, composite material NiO/C

In the present work we report on the study of local atomic and electronic structure of gold nanoparticles funnctionalised by thiol and amine containing long-chain ligands. The study of nanoscale atomic structure is performed by means of X-ray absorption spectroscopy (XANES: X-ray Absorption Near-Edge Structure) and computer simulation. In consequence of the experimantally obtained data analysis and computer simulation it was obtained that strong bonding takes place when 11-mercaptoundecanoic acid is bound to the gold nanoparticles surface, forming a chemical bond Au-S 0.25 nm in length. Weaker bonding is observed when forming bond between dodecylamine and gold nanoparticles surface atom resulting in Au-N bond 0.23 nm in length. Supplementary XANES spectra analysis by means of density functional theory reveals the nature of formation of the investigated nanoscale structure.

Keywords: nanoscale structure of matter, X-ray absorption spectroscopy, XANES, density functional theory, nanoparticles functionalisation

This work deals with the study of atomic and electronic structure of kaolinite samples (Glukhovtsy deposit) and montmorillonite (Millerovsky deposit) by density functional theory. The applicability of existing exchange-correlation potential in the local density approximation (LDA) and the generalized gradient approximation (GGA) is analised for an adequate description of the physical properties of layered aluminosilicate. An experimental and theoretical study of the IR spectra of minerals, as well as the identification of the most intense absorption bands, performed in the approximation of DFT using the exchange-correlation potential PW91. The analysis of the band structure of these minerals, which showed that these compounds are direct-gap insulators.

Keywords: DFT, clay, clay minerals, phyllosilicates, atomic and electronic structure, crystalline systems, IR spectrum band strukutra, the electron density

The influence of manganese nitrate impregnating solutions concentration and temperature dynamic viscosity, the wetting angle, interface “porous tantalum electrode - solution” free surface energy and the impregnation degree of porous tantalum anode was researched. A quantitative characteristic of manganese nitrate solution application on porous tantalum anode of solid-electrolyte capacitor during the process of impregnation was defined and work of adhesion and cohesion was calculated. Thus increasing of solution concentration above 42% wt brings to sharp growth of surface tension and so work of cohesion is increased but carriers impregnation is fallen. The most effective impregnation is realized at concentration 27% wt. This fact corresponds to best value of tantalum anode capacitor free surface energy. So using received data we are able to estimate optimal conditions of impregnation and wetting process by nitrate magnesium.  

Keywords: manganese nitrate, manganese dioxide, limiting wetting angle, free surface energy

"This review covers various methods of synthesis LaMnO3 ferroics. The general analysis of the solid-phase synthesis reactions methods and wet methods (sol-gel, sorption, co-precipitation) are carred out. The original results of LaMnO3 syntheses from various precursors by means of the in situ method are showned. The advantages and disadvantages of different methods of synthesis are determined. The analysis of synthesis LaMnO3 ferroics published data is shown:
- the structure formation of LaMnO3 in perovskite-type phases occurs at different temperatures, depending on precursors states;
- LaMnO3 perovskite phases differ in symmetry and unit cells parameters at room temperature, depending on the preparation conditions;
- the highest synthesis temperature of LaMnO3 are typical for solid phase reactions method (950-1050 ° C), the lowest - for wet synthesis methods (500-700 ° C);
 - the synthesis conditions effect the stoichiometry of LaMnO3 for oxygen content.
Our studies of structure formation processes of LaMnO3 by in situ method are allowed to define the role of precursors states at synthesis of solid phase reactions methods, adsorption, co-precipitation and sol-gel mixtures.
It is determined that in samples prepared by wet chemical methods, the formation processes of  LaMnO3 perovskite phases occur at lower temperatures than by solid phase reaction (sol-gel precursor - 500 <T <600 ° C; precursors obtained by coprecipitation and sorption methods - at 600 <T <700 ° C and 700 <T <800 ° C, respectively).  

Keywords: ferroics, LaMnO3, X-ray diffraction, solid-phase synthesis, sol-gel synthesis, sorption, co-precipitation