Investigation of the influence of technological conditions of microarc oxidation of magnesium alloys on their structural state and mechanical properties

Наведені дослідження структури і властивостей покриттів, отриманих при мікродуговій обробці на магнієвому сплаві. Обробка проводилася при анодно-катодному режимі в лужному електроліті з різними домішками. Показана можливість формування кристалічних оксидних покриттів різного фазового складу (MgO, MgAl₂O₄, Mg₂Sі₄, Mg₃(PO₄)₂) товщиною до 300 мкм, що мають високу адгезію з основою, гарні захисні властивості і високу твердість, яка досягає 6,6 ГПа

The effect of magnetic and electric fields on the processes of food freezing

The article summarizes the results of studies based on scientific publications on the effect of magnetic fields (MF) and electric fields (EF) on the kinetics of freezing processes applied onto biological tissue and on their properties. The processes of freezing food media on installations equipped with the Cells Alive System (CAS) magnetic system manufactured by ABI Co., Ltd., Japan are considered in this article. It is shown that the majority of researchers did not confirm the benefits claimed by the CAS system developers in comparison with the processes of fast freezing in the chambers without the magnetic field. In the case of using the alternating magnetic fields (AMF) with high field induction values, the effect is more pronounced. The application of strong static or alternating EF contributes to the creation of a fine-grained structure of ice, reduces the freezing duration and decreases mass loss during the food thawing

Effect of density of states peculiarities on Hund's metal behavior

We investigate a possibility of Hund's metal behavior in the Hubbard model with asymmetric density of states having peak(s). Specifically, we consider the degenerate two-band model and compare its results to the five-band model with realistic density of states of iron and nickel, showing that the obtained results are more general, provided that the hybridization between states of different symmetry is sufficiently small. We find that quasiparticle damping and the formation of local magnetic moments due to Hund's exchange interaction are enhanced by both, the density of states asymmetry, which yields stronger correlated electron or hole excitations, and the larger density of states at the Fermi level, increasing the number of virtual electron-hole excitations. For realistic densities of states these two factors are often interrelated because the Fermi level is attracted towards peaks of the density of states. We discuss the implication of the obtained results to various substances and compounds, such as transition metals, iron pnictides, and cuprates.Comment: 7 pages, 7 figure

Nonlocal correlations in the vicinity of the α\alpha-γ\gamma phase transition in iron within a DMFT plus spin-fermion model approach

We consider nonlocal correlations in iron in the vicinity of the $\alpha$-$\gamma$ phase transition within the spin-rotationally-invariant dynamical mean-field theory (DMFT) approach, combined with the recently proposed spin-fermion model of iron. The obtained nonlocal corrections to DMFT yield a decrease of the Curie temperature of the $\alpha$ phase, leading to an agreement with its experimental value. We show that the corresponding nonlocal corrections to the energy of the $\alpha$ phase are crucially important to obtain the proximity of energies of $\alpha$ and $\gamma$ phases in the vicinity of the iron $\alpha$-$\gamma$ transformation.Comment: 5 pages, 2 figure

Momentum-dependent susceptibilities and magnetic exchange in bcc iron from supercell DMFT calculations

We analyze the momentum- and temperature dependences of the magnetic susceptibilities and magnetic exchange interaction in paramagnetic bcc iron by a combination of density functional theory and dynamical mean-field theory (DFT+DMFT). By considering a general derivation of the orbital-resolved effective model for spin degrees of freedom for Hund's metals, we relate momentum-dependent susceptibilities in the paramagnetic phase to the magnetic exchange. We then calculate non-uniform orbital-resolved susceptibilities at high-symmetry wave vectors by constructing appropriate supercells in the DMFT approach. Extracting the irreducible parts of susceptibilities with respect to Hund's exchange interaction, we determine the corresponding orbital-resolved exchange interactions, which are then interpolated to the whole Brillouin zone. Using the spherical model we estimate the temperature dependence of the resulting exchange between local moments.Comment: 18 pages, 6 figure

Collector properties - technological and economical aspects of introduction of new technologies

Practical aspects of applying modern technologies of oil mining have been considered taking into consideration collector properties. Methods of designing radically new facies-sedimentation models in effective reservoirs from the viewpoint of collector facies heterogeneity and use of individual development systems within the isolated heterogeneity zones were laid as a basis of increasing efficiency of carbohydrates pool development

Electron correlation effects in paramagnetic cobalt

We study the influence of Coulomb correlations on spectral and magnetic properties of fcc cobalt using a combination of density functional theory and dynamical mean-field theory. The computed uniform and local magnetic susceptibilities obey the Curie-Weiss law, which, as we demonstrate, occurs due to the partial formation of local magnetic moments. We find that the lifetime of these moments in cobalt is significantly less than in bcc iron, suggesting a more itinerant magnetism in cobalt. In contrast to the bcc iron, the obtained electronic self-energies exhibit a quasiparticle shape with the quasiparticle mass enhancement factor ${m^*/m}\sim$1.8, corresponding to moderately correlated metal. Finally, our calculations reveal that the static magnetic susceptibility of cobalt is dominated by ferromagnetic correlations, as evidenced by its momentum dependence.Comment: 5 pages, 5 figure

Paleographic features of formation of petroliferous layers of Vasyugan suite of Western Siberia

It has been shown that active tectonic nodes present within Western Siberian Plate and associated with reformation of spatial wavefield with the periodicity of 18 million years, influences paleogeomorphological peculiarities of sedimentary basin and controls location of Upper Jurassic source area. Paleogeographic schemes of formation time of particular oil-and-gas bearing sand layers of horizon J1 of Vasyugan suite have been built for the first tim

Effect of electrolysis regimes on the structure and properties of coatings on aluminum alloys formed by anode-cathode microarc oxidation

Наведено результати дослідження фазового складу і властивостей МДО-покриттів на алюмінієвих сплавах. Покриття були одержані в лужно-селікатному електроліті на змінному сінусоідальному струмі і в імпульсному режимі струму. Показано, що підвищена щільність мікророзрядів при імпульсної технології збільшує сумарну енергію, що виділяється в них. Це обумовлює підвищення швидкості зростання оксидного покриття і ймовірність утворення α-Al₂O₃ фази. Одержані при мікроплазмове оксидуванні в імпульсному струмовому режимі покриття мають високу твердість і електричну міцніст