Search

ABSTRACT In the process of water treatment from surface water sources, lime mud as waste is formed. This waste contains CaO, Ca(OH)2, and CaCO3. The article proposes a comprehensive method for processing lime mud into high‐strength anhydrite cement. The method involves the interaction of lime mud with waste sulfuric acid from the production of polymer fibers using a structure‐controlled method in the (CaO·Ca(OH)2·CaCO3)—H2SO4—H2O system at a temperature of 40°C. X‐ray diffraction analysis showed the presence of CaSO4 and CaSO4·0.62H2O phases with a purity of 99.8%. The structure‐controlled method makes it possible to control the formation and growth of calcium sulfate crystals of the required shape and size, due to which it is possible to obtain anhydrite cement with desired properties. Combined grinding of synthetic anhydrite with activator additives makes it possible to obtain anhydrite cement with a strength of up to 28.5 MPa.

Subject and Purpose. The solid-state structures involving metasurfaces can be used to effectively control some of the basic properties of electromagnetic waves, like amplitude, phase and polarization. The present work is aimed at analyzing the new effects that may appear during incidence of p-polarized electromagnetic waves upon a solid-state structure involving a uniaxial plasmonic metasurface, a dielectric interlayer, and a layer of metal. Methods and Methodology. The conditions suitable for identifying the effects that result from the reflection of a p-polarized electromagnetic wave incident upon a solid-state structure of the above described type have been sought for via numerical simulation. That has allowed finding the magnitudes of the essential parameters, such as angles of incidence and frequencies of the electromagnetic waves, as well as thicknesses of the dielectric interlayer, that could stipulate appearance of novel electromagnetic effects. Results. It has been shown that the solid-state structure involving a uniaxial plasmonic metasurface, a dielectric interlayer, and a layer of metal is capable, under certain conditions, to fully absorb an incident electromagnetic wave of p-polarization. Moreover, a new effect has been predicted, specifically that of full conversion of the incident p-polarized electromagnetic wave into a reflected wave of s-polarization. The necessary condition is that the plane of incidence of the electromagnetic wave were at an acute angle to the principal symmetry axis of the plasmonic metasurface. Conclusions. The solid-state structures of the type involving a uniaxial plasmonic metasurface, a dielectric interlayer, and a layer of metal are characterized by unique reflective properties. They are capable of fully absorbing, under certain conditions, the p-polarized electromagnetic waves incident upon them. Such structures can be used for creating optical and nanoelectronic devices of new types.

Subject and Purpose. The analysis of the electromagnetic waves’ polarizational transformations that may accompany their reflection from a metasurface is of considerable scientific and practical interest from the point of possibilities for improving characteristics of nanoelectronic and optical devices, and creating novel types of these. This work has been aimed at finding the conditions for efficient conversion of a p-polarized electromagnetic wave incident upon a uniaxial plasmonic metasurface at the boundary of a dielectric layer, into a wave of s-polarization. Methods and Methodology. The effects of conversion of p-polarized electromagnetic waves incident upon a uniaxial plasmonic metasurface, into s-polarized waves were explored through numerical modeling. The approach has allowed determining the wave frequencies and thicknesses of the dielectric layer best suitable for ensuring full conversion. Results. The presence of a uniaxial plasmonic metasurface on top of a dielectric layer can provide for full conversion of an incident p-polarized electromagnetic wave into a wave of s-polarization. As has been established, the effect takes place if the plane of incidence of the p-polarized wave makes an acute angle with the principal axis of the plasmonic metasurface. Another finding is that the full conversion is possible for a variety of permittivity values of the dielectric layer. Conclusions. The uniaxial plasmonic metasurface placed on a dielectric layer is characterized by unique reflective properties. It can have a noticeable impact on polarization of the p-polarized wave’s incident upon the layer. Dielectric layers provided with uniaxial meta-surfaces can be used for creating optical and nanoelectronic devices of new types.

This study investigates the electrochemical degradation mechanisms of nickel–salen (NiSalen) polymers, with a focus on improving the material's stability in supercapacitor applications. We analyzed the effects of steric hindrance near the nickel center by incorporating different bulky substituents into NiSalen complexes, aiming to mitigate water-induced degradation. Electrochemical performance was assessed using cyclic voltammetry, operando conductance, and impedance measurements, while X-ray photoelectron spectroscopy (XPS) provided insights into molecular degradation pathways. The results revealed that increased steric hindrance from methyl groups significantly reduced the degradation rate, particularly in water-containing electrolytes, by hindering water coordination to the Ni center. Among the studied polymers, the highly substituted poly[Ni(Saltmen)] exhibited superior stability with minimal capacity loss. Density functional theory (DFT) calculations further supported that steric protection around the Ni atom effectively lowers the probability of water coordination. These findings suggest that sterically enhanced NiSalen polymers may offer a promising path toward durable supercapacitor electrodes, highlighting the route of molecular engineering to enhance material stability. [ABSTRACT FROM AUTHOR]

Various iron oxides have been proven to be promising anode materials for metal-ion batteries due to their natural abundance, high theoretical capacity, ease of preparation, and environmental friendliness. However, the synthesis of iron oxide-based composites requires complex approaches, especially when it comes to composites with intrinsically conductive polymers. In this work, we propose a one-step microplasma synthesis of polyaniline-coated urchin-like FeOOH nanoparticles (FeOOH/PANI) for applications as anodes in lithium-ion batteries. The material shows excellent electrochemical properties, providing an initial capacity of ca. 1600 mA∙h∙g−1 at 0.05 A∙g−1 and 900 mA∙g−1 at 1.2 A∙g−1. Further cycling led to a capacity decrease to 150 mA∙h∙g−1 by the 60th cycle, followed by a recovery that maintained the capacity at 767 mA∙h∙g−1 after 2000 cycles at 1.2 A∙g−1 and restored the full initial capacity of 1600 mA∙h∙g−1 at a low current density of 0.05 A∙g−1. Electrochemical milling—the phenomenon we confirmed via a combination of physico-chemical and electrochemical techniques—caused the material to exhibit interesting behavior. The anodes also exhibited high performance in a full cell with NMC532, which provided an energy density of 224 Wh∙kg−1, comparable to the reference cell with a graphite anode (264 Wh∙kg−1).

Subject and Purpose. The study of the effect of reflectionless electromagnetic waves propagation through solid-state structures containing metasurfaces at its boundaries has a great scientific and practical interest for improving the performance and creating new types of nanoelectronics and optics devices. The aim of this work is to study the effect of an anisotropic uniaxial plasmon metasurface located at the boundary of the dielectric layer on the effect of reflectionless propagation of electromagnetic waves. The study of the effect of reflectionless propagation of electromagnetic waves through solid-state structures containing metasurfaces at its boundaries is of great scientific and practical interest for improving the performance and creating new types of nanoelectronics and optics devices. Methods and Methodology. Numerical simulations were used to study the effect of the reflectionless electromagnetic waves pro­pagation through an anisotropic uniaxial plasma metasurface lying on the dielectric layer. It is used to determine the thicknesses and permeability values of the dielectric layer, for which the effect was observed. Results. It is shown that the presence of an anisotropic uniaxial plasmon metasurface on the dielectric layer leads to a significant conditions change of the effect of reflectionless propagation of p-polarized electromagnetic waves along and across the main axis of anisotropy of the metasurface. It was shown that the metasurface removes the rigid restriction of the dielectric layer permeability va­lue. To achieve the effect of reflectionless propagation of electromagnetic waves, the permeability of the dielectric layer can be chosen within a wide range. Conclusion. Dielectric layers with anisotropic uniaxial plasmonic metasurfaces have significantly better characteristics for the effect of reflectionless propagation of electromagnetic waves. They can be used to create fundamentally new nanoelectronic and optical devices.

Subject and Purpose. In the context of growing anticipation of fundamentally new optical and radiophysical devices, the present study is concerned with the total electromagnetic wave tunneling through an asymmetric three-layer structure such that contains a conductive negative-permittivity layer. The aim of this work is to recognize how the asymmetry property of this three-layer structure acts on the effect of total wave tunneling with the frequency dispersion of the conductive negative-permittivity layer taken into account. Methods and Methodology. The frequency-dependent conditions of the total electromagnetic wave tunneling through an asymmetric three-layer structure are sought by numerical simulations. A universal approach based on the introduction of dimensionless frequencies and dimensionless layer thicknesses allows us to numerically investigate conditions of the total electromagnetic wave tunneling for any desired frequencies and geometric parameters of the asymmetric three-layer structure. Results. It has been shown that the asymmetry property of the three-layer structure can significantly change the total electromagnetic wave tunneling conditions. It has been demonstrated that parameters of the asymmetric three-layer structure can be selected in such a way as to modify the total electromagnetic wave tunneling conditions toward a desired practical application of the structure. It has been found that a proper choice of the parameters can minimize the action of the three-layer structure asymmetry on the electromagnetic wave tunneling effect. Conclusion. Asymmetric three-layer structures can be of use to effectively change conditions of the total electromagnetic wave tunneling in an effort to provide devices under development with desired characteristics.

Pursuing of straightforward and cost‐effective methods for synthesizing high‐performance anode materials for lithium‐ion batteries is a topic of significant interest. This study elucidates a one‐step synthesis approach for a conversion composite using glow discharge in a nickel formate solution, yielding a composite precursor comprising metallic nickel, nickel hydroxide, and basic nickel salts. Subsequent annealing of the precursor facilitated the formation of the Ni@NiO composite, exhibiting exceptional electrochemical properties as anode material in Li‐ion batteries: a capacity of approximately 1000 mAh g−1, cyclic stability exceeding 100 cycles, and favorable rate performance (200 mAh g−1 at 10 A g

Subject and Purpose. The effect of total electromagnetic wave tunneling through a three-layer structure containing a plasma-like negative-permittivity layer is important for both gaining a better insight into the high-frequency properties of layered solids and, hence, creating new types of high-frequency radio-physical devices. The main purpose is to study the influence the frequency dispersion of the negative-permittivity layer exerts on the electromagnetic wave tunneling through a three-layer structure with an asymmetric dielectric medium. Methods and Methodology. A new universal approach is used, based on introducing dimensionless frequencies and dimensionless layer thicknesses of a three-layer structure. It allows the frequency-dependent conditions of the effect of total electromagnetic wave tunneling to be examined for different frequency ranges and various three-layer structure parameters. Results. It has been shown that taking into account the frequency dispersion of the negative-permittivity layer makes it possible to observe the total tunneling of electromagnetic waves at different frequencies with an appropriate choice of the three-layer structure parameters. In various frequency ranges, the effect of two-frequency total tunneling of electromagnetic waves has been predicted. Conclusion. In the presence of a frequency dispersion of a negative-permittivity layer as part of a three-layer structure, the total electromagnetic wave tunneling conditions of this structure are softened and modified significantly. In this case, unique phenomena arise that can be used to create fundamentally new high-frequency devices in optics, radiophysics, and electronics.

The conductivity of the polymeric energy storage materials is the key factor limiting their performance. Conductivity of polymeric NiSalen materials, a prospective class of energy storage materials, was found to depend strongly on the length of the bridge between the nitrogen atoms of the ligand. Polymers obtained from the complexes containing C3 alkyl and hydroxyalkyl bridges showed an electrical conductivity one order of magnitude lower than those derived from more common complexes with C2 alkyl bridges. The observed difference was studied by means of cyclic voltammetry on interdigitated electrodes and operando spectroelectrochemistry, combined with density functional theory (DFT) calculations.

The paper presents the results on first synchronous observations of variations in auroral luminosity and geomagnetic field, made with high temporal resolution at the ISTP SB RAS high-latitude station Istok (70° N, 88° E) in September–December 2018. Auroras were recorded with all-sky camera, pulsations in the auroras were recorded by a photometer in four spectral ranges with silicon photomultipliers. Continuous monitoring of geomagnetic pulsations was performed using a LEMI-30 three-component induction magnetometer. Both synchronous bursts of auroras and magnetic field pulsations, as well as disturbances of auroras, not accompanied by disturbances in the geomagnetic field, were observed. We note that the photometer clearly recorded short-period (~20 min) variations in in auroral luminosity. At the same time, some instability of the photometer signal level occurred at sufficiently long time intervals. In the photometer data, there are powerful signal bursts, probably of a hardware nature. Nevertheless, the temporary distribution analysis of the registration moments (registration frequency) of signal bursts indicates the possible dependence of the burst registration frequency on the geomagnetic activity level.

Safety issues with lithium-ion batteries prevent their widespread use in critical areas of technology. Various types of protective systems have been proposed to prevent thermal runaway and subsequent battery combustion. Among them, thermoresistive systems, representing polymer composites that sharply increase their resistance when the temperature rises, have been actively investigated. However, they are triggered only when the heating of the battery has already occurred, i.e., the system undergoes irreversible changes. This paper describes a new type of protective polymer layer based on the intrinsically conducting polymer poly[Ni(CH3OSalen)]. The response mechanism of this layer is based on an increase in resistance both when heated and when the cell voltage exceeds the permissible range. This makes it possible to stop undesirable processes at an earlier stage. The properties of the polymer itself and of the lithium-ion batteries modified by the protective layer have been studied. It is shown that the introduction of the polymer protective layer into the battery design leads to a rapid increase of the internal resistance at short circuit, which reduces the discharge current and sharply reduces the heat release. The effectiveness of the protection is confirmed by analysis of the battery components before the short circuit and after it.