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For the first time, based on complex research, a zoo technical justification for the use of PS-2 and PS-4 biostimulators in the technology of calf raising in individual boxes and pavilions is given to activate the body's adaptogenesis to cold and implement the productive qualities of young stock during rearing and fattening in typical premises. Intramuscular injection of PS-2 (polysaccharide complex of yeast cells immobilized in an agar gel by adding a benzimidazole derivative) and PS-4 (similar to PS-2 plus antibiotic of the cephalosporin) to calves in a dose of 3 ml at 2-3 and 7-9 days of life stimulates their growth and development during the raising, rearing, and fattening periods, thereby reducing the incidence of diseases. By the end of the growing, rearing, and fattening periods, the animals of the 1(st) and 2(nd) experimental groups outnumbered their control peers by 7.2 and 8.2 kg; 11.4 and 13.6 kg; as well as 13.8 and 16.8 kg, respectively (P0.05), compared to the control group.

The magnetic characteristics of a nanocrystalline material based on bismuth ferrite Bi2Fe4O9 with 60±3 nm crystallites were studied. The obtained material demonstrates unusual magnetic properties, which are manifested in a significant increase in the value of magnetization in comparison with the data known from other works. Keywords: nanocrystals, bismuth ferrite, mullite, magnetic properties.

The effect of surface functionalization with citric acid on the properties of magnetic nanoparticles (MNPs) ZnxFe3-xO4 (x=0; 0.25; 0.5; 0.75; 1.0) synthesized by the hydrothermal method was studied. To study the properties of MNPs, X-ray diffractometry (XRD) and energy dispersive X-ray spectroscopy (EDS) were used. The magnetic properties of the samples and the phase state of MNPs were studied using a physical property measurement system (PPMS) and Mossbauer spectroscopy (MS). It has been established that the sizes of crystallites and the crystal lattice parameter of ZnxFe3-xO4 MNPs change with increasing Zn2+ concentration. The low values of the coercive force and the presence of a doublet on the MS indicate the presence of both ferrimagnetic and superparamagnetic components. Keywords: ZnxFe3-xO4 ferrite spinel MNPs, hydrothermal synthesis, functionalization of MNPs with citric acid, crystal structure, magnetic properties, magnetic structure.

Studies of the properties of ZnxFe3-xO4 (x=0, 0.25, 0.5, 0.75, 1.0) magnetic nanoparticles synthesized by a modified hydrothermal method are presented in comparison with the properties of the same nanoparticles stabilized with polyacrylic acid ZnxFe3-xO4@PAA. The structure, size, morphology, and magnetic properties of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT IR), physical properties measurements (PPMS), and Mossbauer spectroscopy. The synthesized nanoparticles are single-phase, without additional impurities, have a narrow size distribution and are in the superparamagnetic phase. From the (XRD) measurements, it was found that with an increase in the Zn content from x=0 to x=1.0, the sizes of the nanoparticles were increasing from 17 to 33 nm. Analysis of the Mossbauer spectroscopy data showed that when doped with Zn ions from x=0 to x=1.0, the sizes of the nanoparticles were decreasing from 15 nm to 5 nm. The results of the Mossbauer studies showed that both ZnxFe3-xO4 and ZnxFe3-xO4@PAA has a core/shell type structure in which the core is magnetically ordered, whereas the shell does not have magnetic ordering. Mossbauer studies indicate that the coating of citric acid particles leads to their isolation from each other (i. e., a decrease in the thickness of the paramagnetic shell, and due to this to increasing in the diameter of the core). This (the last sentense) sentense is too long. It could be mode two or three sentences for better clarification. Keywords: ferrite-spinel nanoparticles, hydrothermal synthesis, polyacrylic acid functionalization, Mossbauer spectroscopy, properties, crystal and magnetic structure.

The properties of magnetic nanoparticles (MNPs) of spinel ferrites CoxMn1-xFe2O4 (at x=0.0; 0.2; 0.3; 0.4; 0.5; 0.6; 0.8; 1.0) synthesized by chemical co-precipitation method have been studied. The studies of the synthesized CoxMn1-xFe2O4 MNPs were carried out using X-ray diffraction (XRD), Raman scattering and Mossbauer spectroscopy. The results of XRD, Raman and Mossbaur studies indicate that the obtained CoxMn1-xFe2O4 MNPs are single-phase. It was established from XRD measurements that the average size of CoxMn1-xFe2O4 crystallites is 34.86 nm for MnFe2O4 (x=0) and decreases to 14.99 nm for CoFe2O4 (x=1.0) with increasing Co ions concentration. An analysis of the Mossbaur spectra showed that the average crystallite size varies from 25 nm for MnFe2O4 (x=0) to 12 nm for CoFe2O4 (x=1.0). On the Raman spectra of CoxMn1-xFe2O4 MNPs, in the region of ~620 cm-1, splitting of the A1g line is observed, which means that the studied MNPs have a reverse spinel structure. The intensity ratio of the A1g (1) and A1g (2) peaks indicates a significant redistribution of the Co2+ and Fe3+ cations between tetra- and octahedralpositions in MNPs of the CoxMn1-xFe2O4 ferrite, which is confirmed by Mossbauer data. Mossbaur spectroscopy data indicate that the synthesized CoxMn1-xFe2O4 MNPs consist of large particles with magnetic ordering and small particles in the paramagnetic phase. With an increase in the concentration of Mn ions, the proportion of fine particles increases, which leads to a decrease in the magnetic blocking temperature. The saturation magnetization of MNPs at x=0.2 (Co0.2Mn0.8Fe2O4) is 57.41 emu/g and this sample, as was found in [V. Narayanaswamy, I.A. Al-Omari, A.S. Kamzin, B. Issa, H.O. Tekin, H. Khourshid, H. Kumar, A. Mallya, S. Sambasivam, I.M. Obaidat. Nanomaterials 11, 1231 (2021)] has the highest specific absorption rate. As shown by Mossbauer studies, this is due to the fact that these particles are in a superparamagnetic state and the magnetic blocking temperature of these MNPs is in the region of ~315 K, which is most suitable for the treatment of malignant tumors by magnetic hyperthermia. Thus, the synthesized CoxMn1-xFe2O4 MNPs are promising for biomedical applications. Keywords: spinel ferrites CoxMn1-xFe2O4, magnetic structure, superparamagnetism, Mossbauer spectroscopy, materials for biomedicine.