To satisfy the needs for metrological support of power measurements in the frequency range from 37.5 to 178.6 GHz, the device has been developed and designed for automated measurements, calibrations ...and verification of wattmeters with high accuracy and the ability to adapt to various types of devices under investigation. This paper presents the composition, diagram andgeneral principle of the device. A description of the structure of isothermal calorimetric converters of autocompensation type with dry load and reference body, which are the basis of the device, is given. The implemented algorithms for converting and replacing microwave power with direct current power of the developed calorimetric wattmeters are presented. The measures taken at the manufacturing stage to minimize sources of measurement uncertainty are described. To assess the accuracy of measuring the absorbed power, a mathematical model of the conversion factor has been compiled. Corrections have been introduced into this mathematical model to improve the measurement accuracy of the reproducible microwave power. The obtained basic metrological and technical characteristics of calorimetric wattmeters and comparison equipment of the device are presented. The obtained metrological and technical characteristics correspond to the current level of standard equipment.
Using the model of breast cancer Ehrlich ascites tumor in mice, we showed that a sigle intraperitoneal injection of cardiac glycoside digoxin 1 h before the intraperitoneal injection of cisplatin ...increased the anticancer effect of the cytostatic drug more than twice when recalculated for the dose. It is assumed that the modifying effect of digoxin is determined by the direct inhibition of glycolysis in tumor cells. Taking into account the design of the study, we consider promising the clinical evaluation of the effectiveness of digoxin as a modifier of cisplatin efficiency in intracavitary therapy of ascites cancers with pleural and abdominal dissenmination.
Informative capacity analysis of immunohistochemistry (IHC) and flow cytometry (FCM) in the assessment of estrogen receptor α (ERα) expression in breast cancer tissue was performed. Similar ...frequencies of expression were shown by both methods: 27% of ERα-negative and 73% ERα-positive cases. However, IHC evaluation detected low levels in only 20% of ERα-positive cases, whereas low levels of ERα detected by FCM were 2 times more often (48%). Moreover, FCM revealed positive expression (23–60%) in 33% of IHC ERα-negative cases. Among IHC ER-positive cases, zero ERα expression was detected by FCM in 12.5%. The approaches to minimize errors in routine clinical determination of the estrogen receptor status were proposed.
Peritoneal dissemination and growth of tumor cells in the ascitic fluid in stages III and IV of recurrent ovarian cancer is difficult to treat; resistance to many anticancer drugs used in the ...treatment of solid ovarian cancer is observed at this stage. The author’s hypothesis that the differences in the molecular phenotype of tumor cells for various types of the disease could be an explanation for this. A comparative evaluation of the expression and coexpression of a number of molecular markers (immunofluorescence assay with flow cytometry) was performed using solid and ascitic ovarian cancer cells. In contrast to solid ovarian cancer, ascitic ovarian cancer cells present leukocyte common antigen CD45 and mesenchymal marker vimentin in addition to epithelial marker cytokeratin. In addition to the inhibition of anoikis (specific mechanism of epithelial cell death in a liquid medium in the absence of contact with the substrate), ascitic ovarian cancer cells are characterized by (1) emperipolesis (intracellular migration of leukocytes without damage to the tumor cell), and (2) phenotype of epithelial-mesenchymal transition. Thus, the data on clinically significant molecular differences between solid and recurrent ascitic ovarian cancer was first obtained, opening up opportunities for anticancer therapy, which previously was not used in the treatment of ovarian cancer.
Importance to reduce permeability of rocks arises safety of mining operations and protecting the soil and underground water in the area of industrial waste storage with high contents of water-soluble ...salts. Disadvantage of the existing methods of grouting rocks by soluble salts is either their dissolution with changing of the composition or diluting of the contacting solution. The paper considers the composition of the grouting mixture for the deposition of insoluble calcium salts and its effectiveness in laboratory conditions. The eutonic solution of a four-component KCl–NaCl–CaCl
2
–H
2
O system was used as the initial solution, while saturated solutions of sodium sulfate and carbonate, and sulfuric acid were applied as the precipitators. Efficiency of rock grouting was estimated according to the water or solution filtration rate through the rock (sand, sylvinite, and halite) before and after calcium salt crystallization. Laboratory experiments showed that the precipitation of calcium sulfate responds to the challenge of plugging rocks. The paper proposes some recommendations of protective screens at the bed of the salt tailing piles and slurry storage facilities.
Research subject. To date, two different-age regional sources of noble metals have been identified in the North Caucasus: 1) Caledonian, which includes ultrabasites of the Front Range (Au, Pt, Pd) ...and 2) Hercynian, which features copper-pyrite (Au) and black-shale deposits (Au, Pt, Pd). Noble metals in these sources form large areal accumulations and ore anomalies, thus presenting a great research interest.Materials and methods. This paper reports the results of a long-term geological fieldwork, which consisted in a detailed geological and mineralogical mapping of the Devonian shale and volcanic rocks, as well as of the Ordovician ultrabasites, in the North Caucasus. During this work, maps, diagrams and sections of ore mineralization sites were complied, and collection of lithogeochemical, ore and groove samples was conducted. Laboratory studies included the examination of the obtained samples using geochemical, petrographic, mineragraphic and physico-mineralogical methods.Results. The main sources of Au, Pt and Pd, as well as the genetic types of their deposits were established. Four different-age geochemical anomalies (fields) with a constant total Au, Pt and Pd content of over than 1 g/t were identified.Conclusion. Large-scale Au, Pt and Pd anomalies in the North Caucasus have been discovered, which form a new North Caucasian province of noble metals.
The paper presents the results of a study of the influence of elastic and air-permeable electromagnetic shields based on foiled materials on the levels of electromagnetic radiation in the frequency ...range of 0.4...2.5 GHz, generated by simulators of simulators of devices for unauthorized retrieval of information due to an exposure to these simulators by short radio pulses. This study has been carried out with the aim of experimentally substantiation the possibility of these shields use to protect speech information from leakage via the direct acoustic and parametric channels. In the course of the study, the method based on the use of the hardware and software complex “Locator for the detection of LV-2R devices”, designed to identify transceiver devices for unauthorized retrieval of information based on the resonance phenomena in their antenna systems and in associated filter elements and including an autonomous a generating and receiving unit, the broadband antenna, the personal computer on which special software for detailed information processing is installed, the set of connecting cables and the set of simulators of devices for unauthorized retrieval of information, has been applied. It has been found that elastic and air-permeable electromagnetic shields based on foiled materials reduce the level of electromagnetic radiation generated by simulators of devices for unauthorized retrieval of information due to exposure to them by short radio pulses, to those values at which this radiation can not be recorded by receiving antennas. As a result, it has been concluded that the investigated electromagnetic shields are the promising solution for ensuring the information protection from leakage via the direct acoustic and parametric channels. Such shields are recommended for use as cladding modules for rooms designed for speech information of limited distribution and where devices used for its unauthorized retrieval could be installed or located.
Model of microwave radiation absorption by biological tissues Lagutskiy, I. A.; Davydov, M. V.; Kizimenko, V. V. ...
Doklady Belorusskogo gosudarstvennogo universiteta informatiki i radioèlektroniki,
02/2021, Letnik:
19, Številka:
1
Journal Article
Recenzirano
Odprti dostop
А model of absorption of electromagnetic energy of radiofrequency range by biological tissues is described in the article. The problems of modeling the interaction of microwave radiation and ...biological tissues represented as multilayer structures are considered. Patch-antenna models for six sub-bands overlapping the 500–3500 MHz range are developed. The model of biological tissue was developed on the basis of MRI imaging, which allows for modeling under near real-life conditions. Based on the developed models of transceivers and biotissue, models have been created that allow to analyze the absorption of electromagnetic energy in the near- and far fields of the transmitter. From the results of modelling in the near field we can see that there are certain absorption maxima at frequencies of 750, 938, 1250 and 1357 MHz. Based on the results of the far field modeling it can be noted that in the range of 750 to 1000 MHz there is no absorption peak at 938 MHz. Also, as a result of the simulation, a decrease in the magnitude of absorption starting from 750 MHz was registered. Absorption peak absence is also observed in the area of 1357 MHz frequency. In the range of 2.5–3 GHz both in the near and far fields practically linear decrease of absorption value is observed. When analyzing the influence of structures' sizes on electromagnetic energy absorption in biological tissues, it was found that the nature of change in absorption value is a nonlinear value. In the range of 0.5–2 GHz both increase and decrease of absorption at thickening or thinning of layers is observed. It should also be noted that when the size of each layer increases by 10 %, the peak of absorption in the area of 1156 MHz frequency is observed. For the 2–3.5 GHz range there are no significant changes in the chart shape when the layer thickness changes.
Abstract
The article considers the impact of frequency-modulated signals on an anisotropic medium over oil and gas deposits. Modeling of the components of the tensors of the dielectric constant of ...the medium over hydrocarbon deposits was carried out. The characteristics of the medium over accumulations of hydrocarbons for frequency-modulated signals from the frequency of the carrier oscillation, the frequency modulation index for the right and left polarizations of electromagnetic waves are studied. Methods of searching for hydrocarbons based on the variation in the characteristics of the applied signals are recommended. It is proposed to introduce new search modes to improve the accuracy of determining the boundaries of hydrocarbon deposits. The influence pattern of the dielectric constant of an anisotropic medium on the real and phase components of the tensor components are established. The research results can be applied in the electrical exploration of minerals.
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