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Бюллетень Национального научно-исследовательского института общественного здоровья имени Н.А.Семашко, Выпуск 1 2023

Бюллетень Национального научно-исследовательского института общественного здоровья имени Н.А.Семашко, Выпуск 1 2023

The article considers the nature, causes, determinants and consequences of corruption. As a form of social deviation of a delinquent nature and as a type of crime, corruption has a destructive effect on all spheres of social life, primarily on their management - by redistributing their resources and by replacing social values and goals with group and personal ones. Corruption affects not only states but also international affairs; therefore, we need active opposition to corruption from the world community: International Anti-Corruption Day was included in the calendars of 187 countries including Russia. According to the World Bank, the annual global amount of bribes is 1 trillion US dollars. For many countries, corruption has become a threat to national security, which makes them seek and use effective and often radical measures to counter corruption, and to conduct comprehensive studies of corruption as an objective and widespread social phenomenon. The authors consider corruption on the basis of an interdisciplinary methodology with an emphasis on institutional and structural-functional approaches, which allowed to identify institutional features of corruption, its structure, functions and social consequences, and to assess the efficiency of anti-corruption measures. The article is based on the statistical data on the dynamics of corruption in Russia and the Republic of Bashkortostan in 2012-2020, and on the results of the sociological survey conducted by the Institute for Strategic Studies of the Republic of Bashkortostan in 2020 according to the methodology for assessing corruption described in the Decree of the Government of the Russian Federation. The survey focused on the problems in the interaction of citizens and employees of state and municipal authorities (everyday corruption), and in the interaction of authorities and business (business corruption) (the corresponding samples were 814 and 300 people). The study of everyday corruption was conducted by individual formalized interviews, of business corruption - by the online survey on the Google Forms.

A route for production of fine Bi4Ge3O12 (BGO) powder is sought after to lower the cost of scintillation devices and make their shapes more versatile. A systematic study of highly dispersed BGO crystallization under the hydrothermal-microwave (HTMW) conditions was carried out in the present work. Anionic, cationic and non-ionic surfactants, chelating agents and polyols were used to modify the synthesis and their respective effects on phase composition and morphology were determined. It was shown that chelating agents or other additives that are capable of forming complexes with the bismuth ions allow the production of smaller, non-aggregated particles and have the procedure be scaleable. BGO powders of various morphology were synthesized and study of the optical properties of the product discovered their advantages over traditional single-crystal material. The BGO powders obtained in optimal HTMW conditions are characterized by the presence of a single intense fast scintillation component with a flash time of about 11 ns which is by an order of magnitude less than that observed in single-crystal BGO (327 ns). This suggests the suitability of these powders for the production of scintillation materials with improved properties. This material is promising for creating highly sensitive composite detectors with a high rate of counting events.

The impact of the synthesis method and morphology of the LaFe0.5Sb1.5O6 samples on their catalytic activity in CO oxidation was studied in detail. The samples obtained by solid-phase reaction and co-precipitation showed higher catalytic activity. The features of the morphology, which cause the lowering of catalytic activity, were revealed for the samples synthesized in molten salts with and without preliminary microwave-hydrothermal treatment. A comparative study of all synthesized rosiaites LnFe0.5Sb1.5O6, Ln = La–Pr, LaFe0.5-xGaxSb1.5O6 and also pyrochlore Pr2(Fe,Sb)O7 using an in situ diffuse reflection IR spectroscopy method was undertaken to clarify the mechanism of CO oxidation. It was revealed that in the course of the reaction the intermediate complexes of metal carbonyls are formed on the surface. At the same time, inactive carbonyls, which exist on the of Ce- and Pr-containing samples surface before the reaction mixture is fed, were found. This feature gives rise to a decrease in their catalytic activity. A reaction mechanism occurring via intermediate carbonyl complexes on the active centers - [Sb3+ - VO- - Fe3+] – is proposed. The CO oxidation on completely gallium-substituted samples indicates the existing of an additional channel for proceeding of redox process, which is not associated with Fe3+. It is suggested that the nature of this channel is possibly associated with a rosiaite layered structure, which creates a unique environment conducive to complex adsorption phenomena.

A comparative analysis has been made for the dielectric and electrorheological properties of suspensions of highly dispersed powders of bismuth ferrites BiFeO3 and Bi2Fe4O9 in polydimethylsiloxane PMS-300. Dielectric characteristics (dielectric constant, dielectric loss tangent) for the suspensions in frequency range 2.5–106 Hz have been determined and non-Debye character of relaxation processes in these systems has been revealed. The measured values of dielectric constant for the disperse bismuth ferrites at zero and infinite frequency (e0 and e∞) are 150 and 59 for BiFeO3, 22 000 and 14 for Bi2Fe4O9, respectively. Electrorheological properties of bismuth ferrite suspensions in static electric field (up to 5 kV) in tension, compression, and shear modes have been analyzed. It has been found that the values of electrorheological effect for BiFeO3 suspensions in polydimethylsiloxane PMS-300 are small even at high concentrations of disperse phase (60 wt %). On the contrary, the suspensions of highly disperse Bi2Fe4O9 exhibit distinct electrorheological effect. For 80 wt % Bi2Fe4O9 suspension, the tensile yield point reached ~7 kPa in electric field of 5 kV, while compressive stress was 12 kPa.

X-ray photoelectron spectroscopy has been applied to examine the surface electronic structure of layered oxides CeFe0.5Sb1.5O6 and PrFe0.5Sb1.5O6 with PbSb2O6 structure (sp. g. P‑31m). The analysis of the XP-spectra for both compounds revealed only Ce3+ and Pr3+oxidation state before and after catalytic tests. The observed variation of the Sb5+/Sb3+ and Fe3+/Fe2+ ratios after catalysis can point to that CO oxidation on these catalysts proceeds by virtue of redox transformations Sb3+ ↔ Sb5+ and Fe3+ ↔ Fe2+ with direct involvement of lattice oxygen and anionic vacancies.

The layered oxide BiGeSbO6 has been synthesized for the first time via solid state reaction. Rietveld refinement showed that BiGeSbO6 belongs to PbSb2O6 structural type (P-31m space group) with unit cell parameters a = 5.1314(9), c = 4.9974(1) A, α = 90°, γ = 120°, Z = 1. Using the EXAFS and XANES methods, it was shown that a structural feature of this compound is a strong disordering of the Bi–O octahedron caused by the stereochemical activity of the 6s2 lone pair of Bi3+ electrons. A model according to which one oxygen vertex in the oxygen coordinated Bi3+ octahedron is absent, and the lone pair of electrons builds this polyhedron to the octahedron, was proposed. A particularity of the structure of BiGeSbO6 is that the existing oxygen vacancy does not have a specific position. It was established that BiGeSbO6 does not exhibit any polymorphic transition up until its incongruent melting point Тm = 985°С. Isobaric heat capacity was measured and thermodynamic functions (entropy, enthalpy increment and Gibbs free energy) were calculated for BiGeSbO6 in the 10–1200 K temperature range. We found that the band gap of BiGeSbO6 is due to the allowed direct interband transition with the energy of 3.16 eV. It was shown that BiGeSbO6 has a wide transmission region in the visible and near-IR ranges. BiGeSbO6 is a self-activated phosphor, but its luminescence spectrum is atypical for Bi3+-containing oxides. The luminescent properties of Bi1-xEuxGeSbO6 solid solutions (x = 0.3, 0.5) were also studied.

We report on the first experimental evidence of the electrorheological effect in suspensions of superfine pyrochlore-type Bi1.8Fe1.2SbO7 powders. Tensile-compressive and shear stress studies of the electrorheological fluids, with various filler contents, revealed an exceptionally high electrorheological effect in the materials – the tensile yield strength at 5 kV/mm reached about 20 kPa. The frequency dependencies of dielectric permittivity, dielectric loss tangent, and the conductivity of the suspensions with various filler contents allowed estimation of the dielectric permittivity values for superfine Bi1.8Fe1.2SbO7 particles at zero and infinite frequencies. The study reveals new oxide materials as promising fillers for electrorheological fluids.

We studied the features of the appearance of broadband “white” emission in CaF2-x mol% ErF3 and ZrO2-x mol% Er2O3 (x = 0–25) nanosized dielectric particles upon their excitation by intense laser radiation with λexc = 1550 nm. Comparison of the results of this study with the results obtained previously for other materials doped with Er3+ ions confirmed the thermal nature of the observed emission and made it possible to identify the main factors affecting its occurrence. These include the band gap of the material and the presence of defects in its structure. A method of applying the effect in dermatology is proposed.

A novel process has been developed for the preparation of Bi4Ge3O12 (BGO) by self-propagating high-temperature synthesis. In this method, microwave radiation is used for the first time to heat organic fuel (urea), which allows its decomposition to be uniformly activated throughout the reaction mixture. The key synthesis parameters are the pH of the medium, the volume of the liquid phase in the system, and the way in which the starting mixture is homogenized. Varying these parameters has made it possible to reduce the synthesis time to 3 min. We have obtained BGO samples consisting of quasi-spherical particles, potentially attractive for the fabrication of scintillating ceramics. In addition, we have synthesized powders that have an order of magnitude better kinetic scintillation characteristics in comparison with single-crystal BGO and are thus interesting for designing scintillating materials for highly sensitive detectors.

(Ln1.8Fe0.2)FeSbO7 (Ln = Pr–Tb) mixed oxides have been synthesized via coprecipitation followed by annealing. According to Rietveld refinement results, all of the oxides have the pyrochlore structure (sp. gr. Fd$$\bar {3}$$mz). The (Ln1.8Fe0.2)FeSbO7 compounds have been shown to exhibit high activity for CO oxidation reaction. The best results have been obtained for (Pr1.8Fe0.2)FeSbO7, which has a 90% CO conversion temperature T90 = 385°C. With increasing lanthanide atomic number, T90 rises monotonically from 385 to 550°C in going from Pr to Tb. This behavior is most likely due to the decrease of structural imperfection in the compounds with smaller lanthanide ionic radii.

The existence of a wide range of pyrochlore-like (PL) Ln2FeTaO7 compounds (Ln = Pr–Yb, including Y) with a hexagonal structure (space group R$$\overline{3}$$) was shown. Two new low-temperature methods for the synthesis of Ln2FeTaO7 were developed to reduce the production temperature and time, namely, coprecipitation followed by annealing and synthesis in molten salts NaCl/KCl. The synthesis of PL phases was found to involve the formation of a nanocrystalline metastable fluorite phase, the fluorite irreversibly transforming to a PL phase as the crystallization time or temperature increases. No other transitions in Ln2FeTaO7 were recorded by DSC up to the melting point of 1320–1450°C (depending on the composition of the Ln2FeTaO7 compound). The isobaric heat capacity Cp(T) was measured and the thermodynamic functions (entropy, enthalpy increment, and reduced Gibbs energy) were calculated in the temperature range 5–1300 K for Y2FeTaO7 by the way of example. In the low-temperature region of 2–25 K, an abnormal behavior of Cp(T), apparently related to the Y2FeTaO7 magnetic transition, was detected.

The series of La1-xPrxGa0.5Sb1.5O6 solid solutions (x = 0–1) with PbSb2O6 structure was synthesized. The comparative study of the La1-xPrxGa0.5Sb1.5O6 morphology showed all compounds have net microstructures. Herein the Pr concentration increasing leads to particles size decreasing from 400 up to 200 nm in the samples with low Pr content and to recrystallization and coarsening of the particles in Pr-rich ones. Using LaGa0.5Sb1.5O6 as an example, it was shown that the compounds have a wide transmission region in the visible and IR spectral ranges and are characterized by a low-energy phonon spectrum. An analysis of the spectral-luminescent characteristics revealed the presence of a cross-relaxation process (1D2→1G4) → (3H4→3F4) of Pr3+ ions for La1-xPrxGa0.5Sb1.5O6 at x ≥ 0.07. It was showed that a broadband radiation of thermal nature is observed under laser excitation with λ = 457 nm and a power density of J = 4.65 kW/cm2 for the samples with high (x = 0.4–1) praseodymium content.