On the Finiteness of the Number of Elliptic Fields with Given Degrees of $$S$$ -Units and Periodic Expansion of $$\sqrt f $$

Doklady Mathematics - For a field k of characteristic 0, up to a natural equivalence relation, it is proved that the number of nontrivial elliptic fields $$k(x)(\sqrt f )$$ with a periodic...     

On the size effect in nanocrystalline cerium dioxide: Is the Tsunekawa model correct?

Nanocrystalline cerium-dioxide samples with different coherent-scattering region sizes are analyzed by advanced techniques, specifically, small-angle neutron scattering, X-ray and neutron diffraction, and spectrometry of the chemical shift in the characteristic X-ray lines. The obtained data confirm the presence of the size effect, i.e., the dependence of lattice constants on the size of coherent-scattering regions. Meanwhile, no traces of oxygen nonstoichiometry and a related deviation in the effective degree of cerium oxidation from the standard value are found. The results obtained call into question the Tsunekawa model traditionally used to explain the size effect in this compound.     

Magnetic Liposomes for Remote Controlled High-Molecular Drugs Release under a Low-Frequency Non-Heating Magnetic Field

Moscow University Chemistry Bulletin - Magnetic anionic liposomes (MALip) conjugated with magnetite magnetic nanoparticles (MNPs) are developed for the controlled release of a protease inhibitor...     

Short- and long-range order balance in nanocrystalline Gd2Zr2O7 powders with a fluorite-pyrochlore structure

A series of nanocrystalline Gd₂Zr₂O₇ powders has been studied using a combination of X-ray diffraction and X-ray spectroscopy with synchrotron radiation. It has been shown that isothermal annealing of an X-ray amorphous mixed hydroxide first leads to the formation of an oxide nanomaterial with a defect fluorite structure and clearly pronounced nonequivalence of the local environment of the Gd³⁺ and Zr⁴⁺ ions. Increasing heat treatment temperature results in initiation and growth of nanodomains with pyrochlore-type superstructure ordering of cations inside bulkier crystallites of defect fluorite. To adequately describe the evolution of the real nanocrystalline structure of gadolinium zirconate, a combination of X-ray structural methods sensitive to the averaged crystal structure and local atomic structure should be used.     

Trends in formation of the nanocrystalline structure and cationic ordering in the Dy2O3-HfO2 (1: 1) system

Evolution of the nanocrystalline structure of the complex oxide Dy₂HfO₅ in the course of thermal annealing at temperatures to 1600°C has been studied by a combination of X-ray and synchrotron methods, including traditional and anomalous X-ray diffraction, PDF, EXAFS, and SAXS. The changes in crystallite size upon annealing of the as-synthesized amorphous precursor have been analyzed in detail. The systematic distortions of a fluorite-type perfect crystal structure (space group $Fm\bar 3m$ ) related to the nonequivalence of the local environment of the Dy and Hf cations but not resulting in formation of a pyrochlore-type cationordered structure in this system have been examined.     

Field theory of a viscoelastic medium undergoing a phase transition

The evolution of a medium undergoing a liquid-vitrification type phase transition is represented within the framework of standard gauge theory of a viscoelastic field, where the order parameter specifies the change in behavior of the atomic system. Equations are obtained describing the space-time dependence of the transition parameter and the viscoelastic field. Soliton-like field distributions are studied in various special cases.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 15–20, November, 1987.     

Microscopic treatment of the fracture process in solids

The process of brittle fracture in a solid is presented as the formation and evolution of an ensemble of elementary carriers (frustrons). The latter represent a mesoscopic region of localized strong shear deformations surrounded by an envelope of an elevated level of plastic flow. The conditions of fluctuation generation of frustrons, their characteristics, and the growth of the supercritical cluster are determined. The fracture time is derived.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 29–35, September, 1987.     

Thermal properties of the bottom sediments of the Black Sea

The main factors affecting the thermal properties of bottom sediments and their variability under the actual conditions of aqueous areas (using the Black Sea as an example) are analyzed on the basis of extensive experimental data obtained in the course of long-term expedition research. The results obtained are discussed in relation to problems concerning the accuracy of determining the density of heat flows through the bottoms of inland and marginal seas.