In the work the composite on the basis of fluoroplastic with filler WO3 is studied and its efficiency for protection against X-ray and gamma radiation is proved. The technological scheme of composite production has been developed and its physical and mechanical characteristics have been studied. The composite with 60 wt% of WO3 content has the following properties: density 3.35 f 0.02 g/cm3, Vickers microhardness (at 300 g load) 5.38 f 0.32 HV, flexural strength 18.86 MPa. The gamma-radiation sources used were E(207Bi) = 0.570 MeV with an activity of 50 kBq, E(137Cs) = 0.662 MeV with an activity of 9 kBq, and E(60Co) =1.252 MeV with an activity of 100 kBq. The X-ray radiation sources were isotopes 241Am (half-life T1/2 = 432.1 years; photon energy E = 59.5 keV; radioisotope activity 46 mu Ci) and 109Cd (half-life T1/2 = 461.4 years; photon energy E = 88 keV; radioisotope activity 15 mu Ci). It is shown that for reduction of gamma radiation with energy 1.252 MeV by 50 % a screen from pure fluoroplastic with thickness of 6.301 f 0.654 cm is required, and for composite with 60 wt% WO3 the thickness of screen is 1.5 times less (4.077 f 0.509 cm). Comparison of the linear attenuation coefficient at energy 0.662 MeV with modern analogs confirmed the high efficiency of radiation protection of the developed material. Radiation-thermal modification of the samples was carried out, which allowed to increase their radiation resistance to gamma radiation many times. After radiation-thermal modification the radiation resistance increased up to 1 f 0.1 MGy and 4.5 f 0.2 MGy for fluoroplastic and composite with 60 wt% WO3 content, respectively. And the initial bending strength increased in both materials by 15 % and more.

In the current study, Cu2O/CuO, Cu2O/Cu nanopowders and bimetallic Ag/Cu/Cu2O nanoparticles were successively synthesized using solution combustion, reduction, and co-precipitation methods. XRD, SEM-EDX, FTIR, and TG analysis have been used to characterize and study the synthesized materials. The structure, morphology and elemental composition of the powders were evaluated. It was found that the pH of the medium affected the morphological parameters of the Ag/Cu/Cu2O particles. The synthesized Ag/Cu/Cu2O samples showed fungicidal activity against Fusarium oxysporium 280 phytopathogens. Nanoparticles synthesized at pH = 9 and pH = 7 had a high inhibitory activity and formed a lysis zone with the sizes of 27 and 24 mm, respectively. The results obtained can be used to suppress specific fungal infections of cotton.

In this paper, a coherent X-ray radiation of relativistic electrons in a composite target is developed. The composite target consists of two amorphous layers and one layer having a structure of a periodic layered medium with three different layers per period, located at a given angle relative to the target surface. The paper considers coherent X-ray radiation behind the rear surface of a target, i.e. radiation in a periodic layered medium, in the Laue scattering geometry. Within the framework of the two-wave approximation of the dynamic theory of X-ray diffraction in a periodic layered medium, expressions are obtained that describe the amplitudes of parametric X-ray radiation and diffracted transition radiation. Then, the case when the second layer is a vacuum is considered. Expressions are obtained that describe the spectral-angular and angular densities of PXR, DTR and their interference. The possibility of significantly increasing the spectral-angular density of DTR due to the total contribution to it of transition radiation waves from the amorphous layer, the front boundary of the periodic layered structure and their constructive interference is shown. The possibility of increasing the spectral-angular and angular densities of DTR due to the choice of the asymmetry of the reflection of the electron field and X-ray radiation in the third layer is shown.

The article deals with the problems of creating composite materials for neutron shielding. A method for creating a composite material is proposed and described based on polyethylene and B4C boron carbide. For the first time, the possibility of synthesizing composites of the proposed composition using cryogenic grinding under low-temperature processing conditions was established in this article. The main physical-mechanical, thermal and neutron-protective properties of the composite material were studied depending on the content of B4C. A composite containing 30% boron carbide synthesized using cryogenic grinding has the following mechanical characteristics: flexural strength - 5.96 MPa, flexural strain at flexural strength 8.56 %, Vickers microhardness, 7.7 +/- 0.8 HV200.

The powdered bentonite/iron oxide composite material was synthesized by chemical co-precipitation. The grain size composition, morphology, crystal structure, porosity, and thermal stability of the obtained powder were investigated. It was established that iron oxide exists in the composite as the maghemite/magnetite solid solution with the formula Fe 2.950 O 4 . An increase in the viability of the bacterium Escherichia coli M-17 after culturing in the nutrient medium in the presence of the synthesized bentonite/iron oxide powder was found.

The work investigates the diffracted transition radiation of a relativistic electron crossing a single-crystal plate in the Bragg scattering geometry. Expressions are obtained that describe the spectral-angular density of diffracted transition radiation with and without the multiple scattering of the relativistic electron in a single-crystal plate taken into account. The influence of multiple scattering on the spectrum of diffracted transition radiation of the relativistic electron is shown.

The issue of crystallization of silicon oxide at low temperatures is a topical issue for the electronics of the future. Organosilicon oligomers and polymers are “ideal” sources for obtaining ultrapure silicon ceramics and silicon nanoparticles. This paper presents the results of the synthesis of highly dispersed silicon-carbon powder from an organohydrosiloxane oligomer and the method for increasing its crystallinity at low temperatures. The diffraction pattern of the resulting powder corresponds to the amorphous–crystalline state of the components in this material, as evidenced by two intense and broadened amorphous halos in the region of Bragg angles 2θ = 7–11° and 18–25°. The resulting silicon–carbon powder was subjected to electron irradiation (E = 10 MeV; D = 106–107 Gy). This paper presents the data on the changes in powder properties via IR-Fourier spectroscopy, X-ray phase analysis, and scanning electron microscopy. Irradiation with fast electrons with an absorbed dose of 106 Gy leads to a slight crystallization of the amorphous SiO2 phase. An increase in the absorbed dose of fast electrons from D = 106 to D = 107 Gy leads to the opposite effect. An amorphization of silica is observed. This study showed the possibility of the crystallization of a silicon–carbon powder without a significant increase in temperature, acting only with electron irradiation. It is necessary to continue further research on expanding the boundaries of the optimal doses of absorbed radiation from fast electrons in order to achieve the maximum effect of the crystallization of silicon–carbon powder.

The parametric X-rays and diffracted transition radiation of a beam of relativistic electrons crossing a target with a periodic layered structure in the Bragg scattering geometry are studied. The general case of asymmetric reflection of the electron field relative to the target surface is considered, i.e., the case when the target layers are located at an arbitrary angle to its surface. Expressions are obtained within the two-wave approximation of the dynamic theory of diffraction, which describe the angular densities of parametric X-rays and diffracted transition radiation and their interference. Numerical calculations of the angular densities of radiation are performed for various values of the target and electron-beam parameters. A dependence of the angular densities of parametric X-ray radiation and diffracted transition radiation on the divergence of the electron beam and relationship between the thicknesses of the periodic structure layers are demonstrated. With an increase in the electron energy, the dependence of the angular density of the diffracted transition radiation on the electron-beam divergence increases.

Mechanical dispersion was used to modify ethyl cellulose with the particles of bentonite clay. The prepared ethyl cellulose/bentonite composite film materials were characterized by optical microscopy and X‑ray diffraction. The thermal behaviors of both the films and the initial polymer powder were studied by using differential scanning calorimetry. It was found that the introduction of bentonite reduced the characteristic temperatures of glass transition and melting of the polymer material.

A method for controlling the focusing of an ionizing-radiation beam, for example, a beam of charged particles, is proposed. Ionization is one of the most widely used radiation-detection methods. The effect of the recombination of charge carriers in the working substance of the detector, accompanying ionization, is usually considered as undesirable, which reduces the accuracy of measuring the radiation parameters. However, this effect can be useful and be the basis of a method for determining the maximum degree of focusing of a beam of particles or ionizing radiation. At a fixed value of the total beam current (ionizing-radiation flux), the maximum focusing is determined from the minimum value of the ionization current in a wide-aperture ionization chamber, which is used as a detector. The signal of the ionization chamber changes during focusing even at a fixed value of the beam current due to the dependence of the intensity of the recombination of charge carriers in the working substance of the chamber on their bulk density. The bulk density of carriers, in turn, is proportional to the distribution density of particles of the ionizing-radiation beam in the volume of the working medium of the ionization chamber.

The transport of neutrons and γ quanta of various energies through a polymer composite based on tungsten-filled track membranes is studied. Expressions describing the attenuation coefficients of γ quanta and neutrons in the developed polymer composite are obtained. The change in the intensity of beams of γ quanta and neutrons when passing through a periodic layered structure consisting of polymer composite layers with tungsten and pure tungsten depending on the number of layers is investigated.

An investigation is performed of synthesized halloysite/magnetite composite materials and their porous structure, surface morphology, and physicochemical properties. It is established that the halloysite/magnetite composite samples have values of the effective field of anisotropy and coercive force that are higher than those found for magnetite.

In this paper, we study the influence of multiple scattering of a relativistic electron on diffracted transition radiation (DTR), which arises when this particle crosses a single-crystal target in the Bragg scattering geometry. For this case we have obtained the expressions describing the angular density of DTR both with and without allowance for multiple scattering of the relativistic electron in the target. The paper shows that the multiple scattering leads to a significant increase in the DTR angular density at low energies of the electron.

The paper presents data on the resistance to electron irradiation of polyimide (PI) composite with nano-sized lead filler. PI composite with nano-filler were obtained on the basis of PI track membranes by electrochemical deposition of nano lead into the pores of track membranes. SEM-images, physical-mechanical and dielectric characteristics of PI composite with 70 wt% content of lead filler were examined. The composite was irradiated with 1-5 MeV electrons, and the maximum cumulative dose was 10 MGy. The effective range of an electron in a PI is greater than in a composite based on track membranes at the same initial electron energy: at E = 2 MeV -by 2.08 times, and at E = 5 MeV by 2.33 times.(c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.

A halloysite/magnetite composite material is synthesized via the chemical coprecipitation of iron salts in halloysite pores. The efficiency of removing of a methylene blue thiazine dye from aqueous solutions is investigated using the obtained composite as an adsorbent. A unified model that combines the equilibrium and kinetics of adsorption is used to obtain a mathematical description of the adsorption process. It is shown that unlike standard models of adsorption kinetics (pseudo-first and -second order), the unified model allows us to determine the true rate constant of the process, which is independent of the initial concentration of the dye in a solution.

Halloysite is modified with magnetite nanoparticles by the chemical coprecipitation of iron salts. To characterize the surface and study the physical-chemical properties of the resulting composite and its components (halloysite and magnetite), we use dynamic light scattering, electron microscopy, the low-temperature adsorption–desorption of nitrogen, X-ray diffraction analysis, Mössbauer and IR (infrared) spectroscopy, and magnetic measurements. Energy-dispersive analysis data and X-ray diffraction patterns confirm the modification of halloysite by magnetite nanoparticles, changing the zeta potential and the adsorption capacity of the surface. IR spectral analysis of the studied composites reveal shifts in the characteristic bands of halloysite and magnetite during their formation. The halloysite/magnetite composite samples have a higher field strength of effective anisotropy and coercive force compared to magnetite.

Polystyrene/bentonite/magnetite film composite materials are obtained by mechanical dispersion. The films are characterized by optical microscopy and X-ray diffraction analysis. The thermal behavior is studied by differential scanning calorimetry in a temperature range of 40–140°С. A nonmonotone dependence of the glass-transition point of the composite on the concentration of the modifying additive is found. An explanation of the obtained experimental results using a configuration entropy model is proposed.