Polaron transformations in the realistic model of the strongly correlated electron system

Electron-phonon coupling, diagonal in a real space formulation, leads to polaron paradigm of smoothly varying properties. However, fundamental changes, namely the singular behavior of polarons, occur if non-diagonal pairing is involved into consideration. The study of polaron transformations and related properties of matter is of particular interest for realistic models, since competition between diagonal and non-diagonal electron-phonon contributions in the presence of other strong interactions can result in unconventional behavior of the system. Here we consider the multiband pd-model of cuprate superconductors with electron-phonon interaction and analyze the features of the systems that are caused by the competition of diagonal and non-diagonal electron-phonon contributions in the limit of strong electron correlations. Using the polaronic version of the generalized tight-binding method, we describe the evolution of the band structure, Fermi surface, density of states at Fermi level, and phonon spectral function in the space of electron-phonon parameters ranging from weak to strong coupling strength of the adiabatic limit. On the phase diagram of polaron properties we reveal two quantum phase transitions and show how electron-phonon interaction gives rise to Fermi surface transformation (i) from hole pockets to Fermi arcs and (ii) from hole to electron type of conductivity. We also demonstrate the emergence of new states in the phonon spectral function of the polaron and discuss their origin.Comment: 14 pages, 7 figure

From underdoped to overdoped cuprates: two quantum phase transitions

Several experimental and theoretical studies indicate the existence of a critical point separating the underdoped and overdoped regions of the high-T_c cuprates' phase diagram. There are at least two distinct proposals on the critical concentration and its physical origin. First one is associated with the pseudogap formation for p<p*, with p~0.2. Another one relies on the Hall effect measurements and suggests that the critical point and the quantum phase transition (QPT) take place at optimal doping, p_{opt}~0.16. Here we have performed a precise density of states calculation and found that there are two QPTs and the corresponding critical concentrations associated with the change of the Fermi surface topology upon doping

The effectiveness of pulsed magnitophoresis in the complex treatment of chronic generalized periodontitis with the use of compositions based on silicon-organic glycerohydrogel

The work outlines the main findings of the study the effectiveness of applying a new method of the treatment of chronic generalized periodontitis by means of pulsed magnitophoresis, developed drug composition based on silicone-organic glycerohydrogelВ работе изложены основные результаты исследования эффективности применения нового метода лечения хронического генерализованного пародонтита посредством проведения импульсного магнитофореза разработанной лекарственной композиции на основе кремнийорганического глицерогидрогеля

Lifshitz quantum phase transitions and Fermi surface transformation with hole doping in high-TcT_c superconductors

We study the doping evolution of the electronic structure in the normal phase of high-$T_c$ cuprates. Electronic structure and Fermi surface of cuprates with single CuO$_2$ layer in the unit cell like La$_{2-x}$Sr$_x$CuO$_4$ have been calculated by the LDA+GTB method in the regime of strong electron correlations (SEC) and compared to ARPES and quantum oscillations data. We have found two critical concentrations, $x_{c1}$ and $x_{c2}$, where the Fermi surface topology changes. Following I.M. Lifshitz ideas of the quantum phase transitions (QPT) of the 2.5-order we discuss the concentration dependence of the low temperature thermodynamics. The behavior of the electronic specific heat $\delta(C/T) \sim (x - x_c)^{1/2}$ is similar to the Loram and Cooper experimental data in the vicinity of $x_{c1} \approx 0.15$.Comment: 8 pages, 4 figure

Monitoring of Candidatus Liberibacter solanacearum in carrot seeds

Currently, in the Russian Federation there is an increase in the production of vegetable crops. Potatoes (Solanum tuberosum) and carrots (Daucus carota) are important crops for Russia, the yield of which has increased over the past few years. Candidatus Liberibacter solanacearum (Lso, Zebra chip disease) is a phytopathogen that poses a serious threat to the production of these crops in the world. According to the pest risk analysis, Lso was included in the Eurasian Economic Union (EAEU) Quarantine List in 2018. During the monitoring 30 different cultivars of carrot seeds of different Russian and foreign producers were tested as a scientific purpose and to control infection with the Lso. A preliminary germination of seeds was carried out under laboratory conditions in wet chambers in a thermostat. Carrot seedlings, seed coats and whole seeds of each sample were tested separately. Seven days after the emergence of seedlings, they were separated from the seed coat; seedlings, their seed coat and whole seeds were placed in PBS extraction buffer at a ratio of 1:10 and homogenized, after that DNA was extracted from each sample using the Proba-NK kit (Agrodiagnostica, Russia). The analysis of the extracted DNA samples was carried out by qPCR Fitoskrin reagent kit (Syntol, Russia) to detect the DNA of the Lso. As a result, Lso was detected in six samples: 'Touchon' whole seeds and seed coat, 'Chantenay Royal' whole seeds and seed coat, 'Nantaise amelioree' whole seeds and seed coat. All positive samples were of French origin. It should be noted that in seedlings grown from infected seeds, Lso has not been identified. Seeds of Russian origin were free from the Zebra chip disease. In case of the absence of pathogen transmission through seeds will be confirm in the future a new potential pathway for Ca. L. solanacearum is proposed. © 2021 International Society for Horticultural Science. All rights reserved