On the phonon-induced superconductivity of disordered alloys

A model of alloy is considered which includes both quenched disorder in the electron subsystem (``alloy'' subsystem) and electron-phonon interaction. For given approximate solution for the alloy part of the problem, which is assumed to be conserving in Baym's sense, we construct the generating functional and derive the Eliashberg-type equations which are valid to the lowest order in the adiabatic parameter.The renormalization of bare electron-phonon interaction vertices by disorder is taken into account consistently with the approximation for the alloy self-energy. For the case of exact configurational averaging the same set of equations is established within the usual T-matrix approach. We demonstrate that for any conserving approximation for the alloy part of the self-energy the Anderson's theorem holds in the case of isotropic singlet pairing provided disorder renormalizations of the electron-phonon interaction vertices are neglected. Taking account of the disorder renormalization of the electron-phonon interaction we analyze general equations qualitatively and present the expressions for $T_{c}$ for the case of weak and intermediate electron-phonon coupling. Disorder renormalizations of the logarithmic corrections to the effective coupling, which arise when the effective interaction kernel for the Cooper channel has the second energy scale, as well as the renormalization of the dilute paramagnetic impurity suppression are discussed.Comment: 59 pages, 10 Eps figures, LaTe

Electric-field-induced monoclinic phase in (Ba,Sr)TiO3_3 thin film

We have studied electric-field-induced symmetry lowering in the tetragonal (001)-oriented heteroepitaxial (Ba$_{0.8}$Sr$_{0.2}$)TiO$_3$ thin film deposited on (001)MgO substrate. Polarized micro-Raman spectra were recorded from the film area in between two planar electrodes deposited on the film surface. Presence of \textit{c}-domains with polarization normal to the substrate was confirmed from polarized Raman study under zero field, while splitting and hardening of the \textit{E}(TO) soft mode and polarization changes in the Raman spectra suggest monoclinic symmetry under external electric field

First-principles Calculations of the Electronic Structure and Spectra of Strongly Correlated Systems: Dynamical Mean-field Theory

A recently developed dynamical mean-field theory in the iterated perturbation theory approximation was used as a basis for construction of the "first principles" calculation scheme for investigating electronic structure of strongly correlated electron systems. This scheme is based on Local Density Approximation (LDA) in the framework of the Linearized Muffin-Tin-Orbitals (LMTO) method. The classical example of the doped Mott-insulator La_{1-x}Sr_xTiO_3 was studied by the new method and the results showed qualitative improvement in agreement with experimental photoemission spectra.Comment: 11 pages, 3 Postscript figures, LaTeX, submit in Journal of Physics: Condensed Matte

Regional Resources Capitalization: Theoretical and Methodological Basis

The article substantiates the holistic theoretical approach to the definition of the economic content, dominant characteristics, the structure and features of the regional resource potential as the basis of the regional economy capitalization. The methodological platform, an updated and expanded conceptual and categorical apparatus of capitalization of the regional economy is presented in the paper. The authors conducted identification, classification and structural-functional decomposition of the elements of the resource potential, objectives, subjects, objects and mechanisms of capitalization of the territory taking into account the differentiation of their role, scale and impact on the proces

The nature of the ferromagnetic ground state in the Mn4 molecular magnet

Using ab initio band structure and model calculations we studied magnetic properties of one of the Mn$_4$ molecular magnets (Mn4(hmp)6), where two types of the Mn ions exist: Mn3+ and Mn2+. The direct calculation of the exchange constants in the GGA+U approximation shows that in contrast to a common belief the strongest exchange coupling is not between two Mn3+ ions (J_{bb}), but along two out of four exchange paths connecting Mn3+ and Mn2+ ions (J_{wb}). The microscopic analysis performed within the perturbation theory allowed to establish the mechanism for this largest ferromagnetic exchange constant. The charge ordering of the Mn ions results in the situation when the energy of the excited state in the exchange process is defined not by the large on-site Coulomb repulsion U, but by much smaller energy V, which stabilizes the charge ordered state. Together with strong Hund's rule coupling and specific orbital order this leads to a large ferromagnetic exchange interaction for two out of four Mn2+ --Mn3+ pairs.Comment: 12 pages, 10 figure

Assessment of the Level of Economic Security in the Conditions of Uncertainty

The article is devoted to assessing the economic security of the state, projecting the resulting efficiency factor of socio-economic development in general. Assessment of economic security is presented as a set of socio-economic development indicators based on those parameters that reflect the impact of uncertainty on the conditions of economy security of the state. The values of economy security indicators of the Russian Federation are calculated for the period 2009-201

Mn-Doped BaTiO3Ceramics: Thermal and electrical properties for multicaloric applications

Multiferroic materialsare widely used in microelectronics because they are sensitive to elastic, magnetic, and electric fields and there is an intrinsic coupling between them. In particular, transition metal-doped BaTiO3 is consideredas a viable multiferroic because of the simultaneous presence of ferroelectricity and magnetism.In this work, we study the electrical and thermal properties of Mn-doped BaTiO3 ceramics that can be used for multicaloric applications. We found that Mn doping leads to the broadening and shifting of the phase transition accompanied with simultaneous decrease of latent heat and entropy. Mn doping causes a decrease in the bulk resistivity while contact resistance remains intact. Doped ceramics can withstand high electric fields(up to 40 kV/cm) and exhibit linear I-V characteristics followed by the Schottkylimited current in contrast to earlier observations. As such, these ceramics are promising for multicaloric applications. © 2019 by the authors.Russian Science Foundation, RSF: № 18-19-00512Funding: This work was supported by the Russian Science Foundation (grant № 18-19-00512)

Expression of Staphylokinase Gene S. aureus Strains Isolated from Breast Milk and Clinical Outcomes in Breastfed Infants

© 2016, Springer Science+Business Media New York.This study aimed to look for the presence of the immune evasion gene cluster in the strains of Staphylococcus aureus isolated from breast milk of women and to estimate their possible role in development of infant’s staphylococcal infections. Strains of S. aureus are isolated by bacteriological examination of breast milk in a hospital (24 strains) and an ambulatory (11 strains) basis. Breastfed infants had staphylococcal infections (42.9 %), intestinal infections (5.7 %), and respiratory infections (20 %), and 11 (31.4 %) infants were intestinal carriers of S. aureus. PCR analysis of 35 strains S. aureus was carried out to detect genes of staphylokinase (sak), inhibitor of the system of complement (scn), inhibitor of chemotaxis of leukocytes (chp), and β-hemolysin (hlb). Sak gene was found in 20 (57 %) S. aureus isolates. Scn, chp, and hlb genes in S. aureus isolates were not detected. Infants received breast milk infected with sak positive S. aureus strains more frequently had S. aureus intestinal colonization than infants who received breast milk infected with sak negative S. aureus (OR 4.5 (1.02; 20.30)). Presence of sak gene in S. aureus strains from breast milk was not associated with development of staphylococcal infection in infant (OR 1.2 (0.3–4.7)). In conclusion, sak is an important factor in avoiding immune defense by S. aureus strains in infected breast milk. Expression of sak gene by S. aureus in infected breast milk may be an important factor for S. aureus intestinal colonization of infants, but not the development of staphylococcal infections in breastfed infants

Visible-light-driven metal-free C-H functionalization: access to new bioactive tetrahydroisoquinoline-butenolide hybrids via domino amine oxidation/vinylogous mannich reaction

An efficient metal-free visible-light-driven two-step domino reaction towards new bioactive tetrahydroisoquinoline-butenolide hybrid compounds was developed for the first time. The combination of fluorescein as photosensitizer and thiourea as an additive was found to be the most effective way to promote an aerobic amine oxidation/vinylogous Mannich domino reaction sequence with yields up to 97% for a broad substrate scope. Both experimental and computational evidence supported the crucial role of singlet oxygen in the developed C H functionalization reaction. Furthermore, the data suggest that thiourea is essential due to its ability to act as an electron-transfer mediator and/or scavenger of reactive oxygen species. In addition, in vitro studies of tetrahydroisoquinoline-butenolide hybrid compounds demonstrated their high antischistosomal and anti-cancer activities