High-Power Microwave Wideband Random Signal Measurement and Narrowband Signal Detection Against the Noise Background

A method of both measurement of power parameters of a microwave wideband intense random signal and detection of a narrow-band signal with unknown frequency and power against a background of this wideband signal is presented. This method is based on nonheterodyne frequency and power conversion using a gyromagnetic converter that operates in two regimes: resonance detection and cross-multiplication. The wideband spectrum envelope of a random signal is visualized, and by switching two regimes and using correspondent filtration of the converted RF signal, the narrowband signals can be detected and measured. The block-scheme and operation of a two-channel measuring device combining both functions are discusse

Ensuring the privacy of information in distributed ledger systems with zero-knowledge proofs

This article addresses the privacy issue in distributed ledger technology (DLT) and blockchain. The research focuses on the applied use case of private transactions involving digital assets. The article provides a comparison of various privacy methods, including mixing networks, ring signatures, and off-chain protocols. It is noted that these methods do not achieve the target level of decentralization, which is a crucial property for blockchain. To address these limitations, the article introduces zero-knowledge proof methods, with a particular emphasis on SNARK. Mathematical descriptions of SNARK methods are presented, along with software implementation approaches. The research includes experiments conducted to compare the performance and information security properties of SNARK methods in the use case of private transactions involving digital assets. The experimental results highlight approaches to improve performance using batch verification methods. The findings of this research have practical implications for the development of systems requiring high levels of privacy and decentralization in blockchain-based systems

Application of Composite Gyromagnetic Materials for Absorbing Radiation Produced by Microwave Oven

Composite gyromagnetic radioabsorbing material (RAM) on the basis of polycrystalline hexagonal ferrites is elaborated for the suppression of unwanted radiation produced by microwave ovens (MWO). Results of laboratory investigation of this material application in the MWO having a magnetron source of microwave radiation are represented

Photoinduced Electron Spin Resonance Phenomenon in α

The photoinduced phenomenon in α-Cr2O3 nanoscaled spherical particles was investigated in the temperature range of 150 up to 315 K. An X-band electron-spin resonance spectrometry was employed to probe the magnetic behavior in α-Cr2O3 under an IR illumination in the nanosecond regime. The photoinduced effect on both low and high field ESR signals appears above 280 K and is remarkably enhanced just below Néel temperature TN. Such a photoinduced ESR phenomenon disappears in a reproducible way in the paramagnetic insulating state which occurs above TN of crystalline α-Cr2O3. In the antiferromagnetic phase, that is, below TN, the shift of the low field absorption could be attributed to the interaction of the light with specific Cr3+ ions located in strongly distorted sites correlated to strong ligand-field effect

Multifrequency EPR study of charge transport in doped polyaniline

Polyaniline highly doped with acrylamido-2-methyl-1-propanesulphonic (PANI-AMPSA) and camphorsulfonic (PANI-CSA) acids have been studied at X- (9.50 GHz) and K- (37.5 GHz) bands EPR. Localized Curie-like and mobile Pauli-like spin charge carriers are stabilized in amorphous and crystalline regions of the samples. AC conductivity contributed from these paramagnetic centers was determined. It was shown that, in contrast with PANI-AMPSA, PANI-CSA with higher both d.c. and a.c. conductivity is a more ordered metal with more rigid and planar polymer chains

Women Workers of St. Petersburg in the Late 19th — early 20th Centuries

The article is devoted to the analysis of the conditions of labor activity, as well as the peculiarities of family life and everyday life of women employed at the enterprises of the factory industry of St. Petersburg in the late 19th — early 20th centuries. At the present stage of development of Russia, there is still a high proportion of female labor in industry, which determines the relevance of the problem under study in order to take into account the historical experience in regulating the complex sphere of labor relations. The question of the main factors in the formation of the female labor force in St. Petersburg during the post-reform period is raised in the article. The industries in which female labor was most widely represented are identified. Issues related to the peculiarities of the professional activity of female workers (working conditions, level of wages, problems of social protection, etc.) are discussed in detail. The circumstances of private, personal life are analyzed, the influence of material factors in the life of workers on the family life is revealed. It is concluded that the contradictions between the new status of a woman, who is able to independently determine her own fate, and the preservation of her unequal position in society, led to the wide participation of women workers in the political life of St. Petersburg during the First World War and the 1917 revolution

Improvement of P3HT-ICBA solar cell photovoltaic characteristics due to the incorporation of the maleic anhydride additive: P3HT morphology study of P3HT-ICBA and P3HT-ICBA-MA films by means of X-band LESR

© 2014 Published by Elsevier B.V. A light-induced electron spin resonance (LESR) X-band study of poly(3-hexylthiophene)/indene-C60 bisadduct P3HT/ICBA flexible solid films containing the additive maleic anhydride (MA) is presented. An increase of P3HT crystalline domain orientation in P3HT:ICBA:MA in comparison with P3HT:ICBA films was confirmed by the angular LESR spectra dependence of P3HT positive polarons. It was assumed that the average increase of power conversion efficiency in P3HT:ICBA:MA solar cells films, relative to P3HT:ICBA, is connected with the more effective crystalline P3HT phase orientation due to the MA sublimation from the composites blends during annealing. The relative average increase of power conversion efficiency of SC films containing MA in comparison to pure P3HT:ICBA blends is estimated to be a factor of (1.15) higher, while the concentrations of functional composites (polymer/fullerene) in blends made with MA decrease by up to 25-30%

Time-resolved ESR studies on transient radicals photogenerated in solutions of melamine in ethylene glycol

Chemically Induced Dynamic Electron Polarization (CIDEP) spectra of transient radicals generated by laser pulse with λ = 248 nm in solutions of melamine in ethylene glycol have been studied by means of time-resolved (TR) ESR at room temperature. The main products are radicals of the solvent molecules formed through abstraction of hydrogen from ethylene glycol by excited melamine molecules and a melamine radical with attached hydrogen atom on melamine. Parameters obtained from well resolved TR ESR spectra coincide with parameters of radical of ethylene glycol HOC{radical dot}HCH2OH and methylol {radical dot}CH2OH, and an unresolved ESR spectrum was attributed to the melamine radical. The electron spin polarization results from the radical pair mechanism (RPM) involving S-T0 mixing (ST0M) and additionally from a small part of triplet mechanism (TM). In order to establish the possible structure and nature of melamine radical quantum-chemical calculations by the DFT B3LYP method using several different basis sets have been done. The reaction pathway and mechanisms of alcohol and melamine radicals formation are proposed and supported by DFT calculations within B3LYP and CIS(D) methods. Melamine and ethylene glycol free radicals relaxation time T2 was estimated as 1.5 and 0.5 μs, respectively. © 2005 Elsevier B.V. All rights reserved

The C-H bond activation in 1-ethyl-3-methylimidazolium acetate-copper(ii) acetate-water-air (dioxygen) systems

Ionic liquid (1-ethyl-3-methylimidazolium acetate, [C2C 1im][AcO])-copper(ii) diacetate monohydrate-water-air (O2) systems have been investigated by 13C NMR, EPR, spectrophotometry, HPLC, and synthetic chemistry methods at different temperatures. The C-H bond activation of [C2C1im]+ with the formation of the unusual dication 1,1′-diethyl-3,3′-dimethyl-2,2′- biimidazolium ([(C2C1im)2]2+) at 50°C and 1-ethyl-3-methyl-1H-imidazol-2(3H)-one (C2C 1imO) at 50-85°C was revealed. Two new complexes with the above compounds, [(C2C1im)2][Cu(AcO)4] and Cu2(AcO)4(C2C1imO)2, were isolated from the systems and characterized by X-ray structural analysis. Catalytic cycles with the participation of copper(ii) acetate and dioxygen and the production of [(C2C1im)2]2+ and C2C1imO have been proposed. The catalysis presumably includes the formation of the CuII(O2)CuII active centre with μ-η2:η2-peroxide bridging in analogy with tyrosinase and catechol oxidase activity. © 2014 The Royal Society of Chemistry

Multifrequency X,W-band ESR study on photo-induced ion radical formation in solid films of mono- and di-fullerenes embedded in conjugated polymers

Anion-cation radical formation in solid films of M3EH-PPV blended with C60-PCBM, C120-O-PCBM and C60-MDHE, C 120-O-MDHE under diode laser (532 nm) and Xe-lamp light excitation studied by means of X,W-band at temperatures 30-80 K is reported. Subsequent high frequency W-band ESR data demonstrate the reproducible, but variable effect of appreciable dispersion (D) contribution in the ESR spectral line for the di-fullerene anion radicals. It is suggested that the increase of the D part relative to the absorption (A) in the summarized ESR absorption line in blends with difullerenes is caused by the higher value of difullerene medium conductivity. The obtained data are quantitatively discussed by the D/A ∼ F(d/δ) functional dependence in approach of plane film geometry, where d is the film thickness and δ is the skin-depth. The influence of ν-dependent δ at D/A value has been checked using X-band LESR. © 2014 Elsevier Ltd. All rights reserved