Using additive technologies to create broadband antennas with fractal geometry

The paper presents the results of a study of the frequency dependence of the S11 parameters of antenna samples with fractal geometry, created using 3D printing technology, followed by the deposition of a conductive copper coating by galvanization. It is shown that changing the dimension of the fractal at different iterations, shifting and dividing the resonant frequencies, it is possible to flexibly form the working bands of antennas in any frequency range and any width. The developed designs can be used to create broadband rectennas.

Passive Measurements of the Refractive Index of Liquid Nitrogen and Free-flowing substances by the Prism Method in the Millimeter Wavelength Range

It is proposed to use the classical prism method in the millimeter wavelength range for measuring the refractive index of liquid and free-flowing substances, including mixtures with particle sizes comparable to the wavelength. The method is implemented using a hollow radio transparent rectangular prism filled with a test substance. The measurements were carried out in the thermal radiation mode using radiometers with horn-lens antennas at frequencies of 37.5 and 94 GHz. To measure the deflection of the refracted beam, a linear scanner with a black body mounted on it, cooled with liquid nitrogen, was used. The distance between the prism and the scanner was 1 m. The refractive index of liquid nitrogen, sand, gravel, marble chips and granular polyethylene were measured. Using the refractive formula and the Landau-Lifshitz-Looeng formula for calculating the dependence of the refractive index of binary mixtures on the bulk density of particles, estimates of the refractive index of the material of the particles that make up the substances under study are obtained. They are in satisfactory agreement with the known experimental data for quartz, feldspar, granite, and marble.

40 years of the Institute of Chemistry and Chemical Technology of SB RAS

Information on the organization and activities of the Institute of Chemistry and Chemical Technology of the Krasnoyarsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences is presented. Its scientific directions are highlighted, the results of fundamental scientific and applied research, participation in the creation of technologies for deep processing of mineral and organic resources of Siberia, hydrocarbons and biomass, organization of the development of the scientific potential of the region, international cooperation are noted.

Structure and electrical conductivity of polyvinyl alcohol films with multi-walled carbon nanotubes, cured in a magnetic field

The results of the study of the effect of the permanent magnetic field of a neodymium magnet on the polymerization process and the electrophysical characteristics of polyvinyl alcohol (PVA) films with the inclusion of multi-walled carbon nanotubes (MWCNTs) are presented. When studying the morphology of films using a scanning electron microscope, it was found that nanocomposite films with a thickness of 30 microns, cured in the presence of a magnetic field with the direction of the magnetic induction vector perpendicular to the surface of the films, have a homogeneous structure, while a significant number of MWCNTs agglomerations are observed in control samples of films. Measurements of the conductivity of films in the direction of the MWCNTs orientation at direct and alternating current showed that the conductivity of films obtained in a magnetic field significantly (by almost two orders of magnitude) exceeds the conductivity of control samples. The obtained results are analyzed on the basis of known models of electrical conductivity of nanocomposites with oriented MWCNTs. The degree of orientation of the MWCNTs during the curing of films in a magnetic field is estimated, taking into account the increase in the viscosity of the nanocomposite during the curing process.

Spin current and spin magnetoresistance of the heterostructure iridate/manganite interface

Kotelnikov Institute of Radioengineering and Electronics of Russian Academy of Sciences The paper presents the results of fabrication and structural study of SrIrO3/La0.7Sr0.3MnO3 heterostructures. The results of experimental studies of the spin current arising in the regime of ferromagnetic resonance are presented. The spin-orbit interaction present in 5d-oxides of transition metals, which is SrIrO3, provides an effective conversion of spin current to charge current due to the inverse spin Hall effect. The angular dependence of spin magnetoresistance makes it possible to determine the angle of the spin Hall effect.

Simulation of the characteristics of low-voltage gates on combined cylindrical surrounding gate field-effect nanotransistors

The applicability of the architecture of a nanoscale surrounding gate field-effect transistor with a combined cylindrical working area for low-voltage applications is discussed. At the same time, the licensed TCAD Sentaurus instrument and technological modeling system is used as a tool. The transistor architecture under consideration involves combining the working zones of n-channel and p-channel transistors with one common gate. At the same time, the efficiency of suppressing short-channel effects is maintained and a high level of transistor current is provided in the strong inversion mode. Based on this architecture, a TCAD model of the NAND gate has been developed, the design of which contains two independent surrounding gates one combined working area. The use of the proposed gate architecture makes it possible to reduce the number of required transistor structures per gate by three times. This leads to a decrease in the switched capacity and power dissipation. From the simulation results, the gate geometric parameters with a working area length of 25 nm and a diameter of 8.5 nm, which can function at control voltages of 0.5 V in the frequency range up to 20 GHz with high gain, are determined. The switching time delay is 0.81 ps. The TCAD model of a half-adder is developed in the basis 2NAND. According to the simulation results, the efficiency of the prototype, which performs binary code addition operations with a delay of 4.2 ps at a supply voltage of 0.5 V and a frequency of 20 GHz, is shown. The obtained results create a theoretical basis for the synthesis of low-voltage complex functional blocks with high performance and minimal occupied area, which meets modern requirements for digital applications.

Millimeter-wave band subsurface sounding module

Radio-wave devices are used for many environmental and material research tasks. These devices and the development of relatively simple and affordable quasi-optic radio wave receivers and transmitters of millimeter and terahertz bands are important for numerous applications. Results of the design of a terahertz-band quasioptical transmitter-receiver module are presented. The module is intended for the remote detection of various objects and for measuring the depolarized field components backscattered by various long objects hidden behind obstacles (building materials and/or everyday items that prevent visual contact with the objects). These may be interfaces between materials with different dielectric constants, fiber optic cables, electric cables, and otherobjects. Results of full-scale experimental testing of the module on the detection of electric cables buried under plater in the wall of a building are presented.

Characteristic form of dynamics equations of Cosserat medium

In this paper, we construct the characteristic form of the equations of dynamics of the Cosserat medium and the Cosserat pseudocontinuum for bounded bodies. The method of matrix transformations proposed by the author is used for construction and allows obtaining the necessary relations using identical transformations. The obtained equations are compared with those for a symmetrically elastic isotropic homogeneous body. A method is proposed for selecting the necessary equations for computational schemes at the internal and boundary points of the body. A sequence of operations is proposed for iterative calculations of stresses, particle velocities, moment stresses, and angular velocities of particles in a coupled model of the Cosserat medium.

Joint transmutation of stable Cs and Sr isotopes in microbiological systems and prospects for accelerated deactivation of liquid radioactive waste

It was found during the research that in the experimental and control bioreactors, which at the beginning of the experiments contained only cesium and strontium, by the end of the experiments, yttrium and barium were found. These isotopes are formed as a result of low-energy nuclear reactions involving protons. In addition, in experimental bioreactors with an optimal composition, a two to threefold increase in the concentration of yttrium was recorded in comparison with the control non-optimal experiments. Accumulation of strontium and cesium in biomass was registered, which is explained by the process of biosorption. It is known that biosorption is the first step towards nuclear transformation (biotransmutation). At the same time, one of the main conditions for the nuclear transformation of biomass elements is its maximum efficient growth. An unexpected fact discovered during the experiment is that yttrium and barium were also found in the control bioreactor, where no biomass was added before the experiment, but only deionized water, glucose, and the initial stable cesium and strontium salts. It is important to note that these elements were not detected in the analysis of the initial salts, substrates, and deionized water. Most likely, the presence of yttrium and barium is due to inoculation of the control fluid of the bioreactor (where no biomass pellets were added) with microorganisms from the experimental bioreactors during their periodic opening for taking current pH samples and adding glucose. Also, the work recorded a decrease in the content of cesium and strontium in the liquid by 20% and 55%, respectively, which goes beyond the statistical error.

Investigation of thin films for fabrication of Nb/AlN/NbN tunnel junctions and microstrip lines of NbTiN-SiO2-Al.

The surface of thin films of Nb, Al, NbTiN, SiO2, Al2O3 is investigated in this work. These films are necessary for the fabrication of high-sensitive devices of THz range. The fabrication processes of such devices are described briefly. All films were fabricated using a Kurt J. Lesker magnetron sputtering system. The study of the film surface roughness was carried out using a Bruker Ikon atomic force microscope. The surface quality of films is determined not only deposition mode, but plasma etching process also. The best values of the root-mean-square deviation of the surface profile Rq = 2 nm were obtained for the used NbTiN film with a thickness of 325 nm. Thin Al-layers that is used for tunnel barrier formation is studied. It is shown than Al films with a thickness of more than 6 nm are already continuous. The surface roughness of the single-layer and multilayer films has been studied.