Phonon anomalies and electron-phonon interaction in RuSr_2GdCu_2O_8 ferromagnetic superconductor: Evidence from infrared conductivity

Critical behavior of the infrared reflectivity of RuSr_2GdCu_2O_8 ceramics is observed near the superconducting T_{SC} = 45 K and magnetic T_M = 133 K transition temperatures. The optical conductivity reveals the typical features of the c-axis optical conductivity of strongly underdoped multilayer superconducting cuprates. The transformation of the Cu-O bending mode at 288 cm^{-1} to a broad absorption peak at the temperatures between T^* = 90 K and T_{SC} is clearly observed, and is accompanied by the suppression of spectral weight at low frequencies. The correlated shifts to lower frequencies of the Ru-related phonon mode at 190 cm^{-1} and the mid-IR band at 4800 cm^{-1} on decreasing temperature below T_M are observed. It provides experimental evidence in favor of strong electron-phonon coupling of the charge carriers in the Ru-O layers which critically depends on the Ru core spin alignment. The underdoped character of the superconductor is explained by strong hole depletion of the CuO_2 planes caused by the charge carrier self-trapping at the Ru moments.Comment: 11 pages incl. 5 figures, submitted to PR

Interaction in the Systems with Tl(І), Hg(ІІ), Pb(ІІ), Si(IV).

Методами РФА та ДТА досліджено фазові рівноваги у квазіпотрійних системах Tl2Х–{Hg, Pb}X–SiX2 (X – S, Se). Установлено існування нових тетрарних еквімолярних сполук. Методом порошку розшифровано кристалічну структуру Tl2HgSiSe4 (ПГ I-42m) та Tl2PbSiS4 (ПГ P21/a). The phase equilibria of the quasi-ternary systems Tl 2Х–{Hg, Pb}X–SiX2 (X – S, Se) were investigated by X-ray phase analyse and DTA. New quaternary phases with equil ratio components were found in these systems. Crystal structures of Tl2HgSiSe4 (S. G. I-42m) and Tl2PbSiS4 (S. G. P21/a) were determinated by X-ray powder diffraction

РАДІОЗАХИСНІ ВЛАСТИВОСТІ 2-МЕРКАПТОБЕНЗОТІАЗОЛУ НА КЛІТИНИ IN VITRO

Aim: to study the radioprotective properties of 2-merсaptobenzothiazole on proliferating cell culture test system.Material and Methods. Cytological, statistics.Results. Upon the incubation of inoculated cellline L929 with 2-merсaptobenzothiazole in the concentration range 0.03–3.00 µg/mL statistically significant change (p≤0.05) of cell population density in mono layer cultures was not found. At the same time for all the applied reagent concentrations stimulation of mitotic activity in the terminal (5th day) stage of cultivation was observed. Exposure of cells by gamma-quanta of 60Co in doses of 1, 5 and 10 Gyled to dose-dependant morphological changes in cell culture. The irradiation of cells in the presence of 2-mercaptobenzothiazole significantly reduced the negative effect of radiation on the indicators of vitality of cells and their differentiation in culture.Conclusions. Quantitative evaluation of radioprotective properties of 2-mercaptobenzothiazole in the test systems of culture of myogenic cells as well as in the L929 line (fibroblast cells) revealed that the highest coefficients of protection (0.31–0.36) and maximum level of factor of dose reduction (4) were observed at 3 mg/ml reagent concentration (irradiation dose – 1 Gy). According to the literature data and our research results, 2-mercaptobenzothiazole might be considered as a reagent with radioactive properties for cells in vitro.Целью работы было исследование радиопротекторных свойств 2-меркаптобензотиазола в тест-системах первичной и перевиваемой культур пролиферирующих клеток.Материал и методы. Использовали цитологические и статистические методы.Результаты. При инкубации перевиваемых клеток линии L929 с 2-меркаптобензотиазолом в диапазоне концентраций 0,03–3,00 мкг/м не было выявлено статистически достоверного изменения (р≤0,05) плотности клеточной популяции в монослойных культурах. В то же время наблюдали для всех примененных концентраций реагента стимуляцию митотической активности на терминальной (5 сутки) стадии культивирования. Облучение клеток гамма-квантами 60Со в дозах 1, 5 и 10 Гр привело к дозозависимым морфофункциональным изменениям в культуре клеток. Облучение клеток в присутствии 2-меркаптобензотиазола существенно уменьшило негативное влияние радиации на показатели жизнеспособности клеток и их дифференциацию в культуре.Выводы. Количественная оценка радиопротекторных свойств 2-меркаптобензотиазола в тест-системах культуры миогенных клеток и линии L929 (фибробластоподобные клетки) показала, что наивысшие показатели коэффициента защиты (0,31–0,36) реагент показал при концентрации 3 мкг/мл при облучении в дозе 1 Гр, а фактор уменьшения дозы был максимальный – 4, при концентрации 3,00 мкг/мл. По совокупности данных литературы и результатов собственных исследований можно считать 2-меркаптобензотиазол реагентом с радиопротекторными свойствами для клеток in vitro.Метою роботи було дослідження радіопротекторних властивостей 2-меркаптобензотіазолу у тест-системах первинної та перещеплюваної культур проліферуючих клітин.Матеріал і методи. Використовували цитологічні і статистичні методи.Результати. При інкубації перещеплюваних клітин лінії L929 з 2-меркаптобензотіазолом у діапазоні концент­рацій 0,03–3,00 мкг/м не було виявлено статистично достовірної зміни (р≤0,05) щільності клітинної популяції у моношарових культурах. Водночас спостерігали для усіх застосованих концентрацій реагенту стимуляцію мітотичної активності на термінальній (5 доба) стадії культивування. Опромінення клітин гамма-квантами 60Со в дозах 1, 5 та 10 Гр призвело до дозозалежних морфофункціональних змін у культурі клітин. Опромінення клітин у присутності 2-меркаптобензотіазолу істотно зменшило негативний вплив радіації на показники життєздатності клітин та їх диференціацію в культурі.Висновки. Кількісна оцінка радіопротекторних властивостей 2-меркаптобензотіазолу у тест-системах культури міогенних клітин та лінії L929 (фібробластоподібні клітини) показала, що найвищі показники коефіцієнта захисту (0,31–0,36) реагент показав при концентрації 3 мкг/мл при опроміненні в дозі 1 Гр, а фактор зменшення дози був максимальний – 4, за концентрації 3,00 мкг/мл. За сукупністю даних літератури та результатів власних досліджень можна вважати 2-меркаптобензотіазол реагентом із радіопротекторними властивостями для клітин in vitro

TESTING POTATO COLLECTION SAMPLES FOR THE PRESENCE OF GENES FOR RESISTANCE TO PHYTOPATHOGENS BY MEANS OF DNA MARKERS

The development of phytopathogen-resistant varieties is the most reliable and economic way to reduce potato yield losses. Breeding of such varieties is possible by using genetic sources of resistance. The use of DNA markers for identification of valuable genotypes, including forms with several resistance genes, makes it possible to significantly improve breeding efficiency. The development of a multiplex PCR technique and using it to simultaneously test varieties and breeding lines for several genes that control the resistance to viruses and nematodes is a new approach to using DNA markers. This study is aimed at screening samples from the collection of the Narym Department of  Breeding and Seed Production of the Siberian Research Institute of Agriculture and Peat (the Branch of the Siberian Federal Agrobiotechnology Research Center, the Russian Academy of Sciences) using the multiplex PCR technique, for genes for resistance to Globodera rostochiensis and Globodera pallidas, potato wart disease, viruses X and Y. 40 samples were tested by means of genetic markers to identify genes for resistance to potato wart disease (Sen1), virus X (Rx), virus Y (Ryadg, Rychc, Rysto), Globodera rostochiensis (H1, Gro1-4) and Globodera pallida (Gpa2), in the genome. The sample included two varieties, three populations produced by self-pollination of the Ideal variety, and 35 individually selected potato hybrids. As a result, we identified marker NL25 (Sen1) in 19 samples; marker PVX (Rx) in 13 samples; marker RYSC3312 (Ryadg) in 10 samples; marker YES3-3A341 (Rysto) in 5 samples; markers TG 689141, 57R450, N195337 (H1) in 12 samples; marker Gro1-4-1602 (Gro1-4) in 6 samples; marker Gpa2-2452 (Gpa2) in 13 samples. In terms of economically valuable traits, sample С-31-15 is noted for high yield and quality indicators. It carries genes for resistance to potato virus X (Rx), Y (Rysto), Globodera rostochiensis (H1, Gro1-4), and Globodera pallida (Gpa2)

Quasi-linear Stokes phenomenon for the second Painlev\'e transcendent

Using the Riemann-Hilbert approach, we study the quasi-linear Stokes phenomenon for the second Painlev\'e equation $y_{xx}=2y^3+xy-\alpha$. The precise description of the exponentially small jump in the dominant solution approaching $\alpha/x$ as $|x|\to\infty$ is given. For the asymptotic power expansion of the dominant solution, the coefficient asymptotics is found.Comment: 19 pages, LaTe

Correlation between the Josephson coupling energy and the condensation energy in bilayer cuprate superconductors

We review some previous studies concerning the intra-bilayer Josephson plasmons and present new ellipsometric data of the c-axis infrared response of almost optimally doped Bi_{2}Sr_{2}CaCu_{2}O_{8}. The c-axis conductivity of this compound exhibits the same kind of anomalies as that of underdoped YBa_{2}Cu_{3}O_{7-delta}. We analyze these anomalies in detail and show that they can be explained within a model involving the intra-bilayer Josephson effect and variations of the electric field inside the unit cell. The Josephson coupling energies of different bilayer compounds obtained from the optical data are compared with the condensation energies and it is shown that there is a reasonable agreement between the values of the two quantities. We argue that the Josephson coupling energy, as determined by the frequency of the intra-bilayer Josephson plasmon, represents a reasonable estimate of the change of the effective c-axis kinetic energy upon entering the superconducting state. It is further explained that this is not the case for the estimate based on the use of the simplest ``tight-binding'' sum rule. We discuss possible interpretations of the remarkable agreement between the Josephson coupling energies and the condensation energies. The most plausible interpretation is that the interlayer tunneling of the Cooper pairs provides the dominant contribution to the condensation energy of the bilayer compounds; in other words that the condensation energy of these compounds can be accounted for by the interlayer tunneling theory. We suggest an extension of this theory, which may also explain the high values of T_{c} in the single layer compounds Tl_{2}Ba_{2}CuO_{6} and HgBa_{2}CuO_{4}, and we make several experimentally verifiable predictions.Comment: 16 pages (including Tables) and 7 figures; accepted for publication in Physical Review

Fermi Resonance in Phonon Spectra of Quaternary Chalcohenides of the type Cu2ZnGeS4

The experimental resonant and non-resonant Raman scattering spectra of the kesterite structural modification of Cu2ZnGeS4 single crystals are reported. The results are compared with those calculated theoretically within the density functional perturbation theory. For the majority of lines a good agreement (within 2–5 cm−1) is established between experimental and calculated mode frequencies. However, several dominant spectral lines, in particular the two intense fully symmetric modes, are found to deviate from the calculated values by as much as 20 cm−1. A possible reason for this discrepancy is found to be associated with the Fermi resonant interaction between one and two-phonon vibrational excitations. The modelling of spectra, which takes into account the symmetry of interacting states, allows a qualitative description of the observed experimental findings. Due to the similarity of the vibrational spectra of Cu2A II B IV S4 (A  =  Zn, Mn, Cd; B  =  Sn, Ge, Si) chalcogenides, Fermi resonance is argued to be a general phenomenon for this class of compounds

The first record of natural transfer of mitochondrial DNA from Pelophylax cf. bedriagae into P. lessonae (Amphibia, Anura)

The unidirectional natural transfer of mitochondrial (mt) DNA from Pelophylax lessonae into P. ridibundus is a common phenomenon in central Europe. Cases of mtDNA exchange between P. lessonae and other non-clonal species of the genus Pelophylax have been unknown so far. In this paper, we describe the first case of mtDNA transfer from P. cf. bedriagae into P. lessonae, which was found in National Park «Smolny», Republic of Mordovia, Russia

Long-range transfer of electron-phonon coupling in oxide superlattices

The electron-phonon interaction is of central importance for the electrical and thermal properties of solids, and its influence on superconductivity, colossal magnetoresistance, and other many-body phenomena in correlated-electron materials is currently the subject of intense research. However, the non-local nature of the interactions between valence electrons and lattice ions, often compounded by a plethora of vibrational modes, present formidable challenges for attempts to experimentally control and theoretically describe the physical properties of complex materials. Here we report a Raman scattering study of the lattice dynamics in superlattices of the high-temperature superconductor $\bf YBa_2 Cu_3 O_7$ and the colossal-magnetoresistance compound $\bf La_{2/3}Ca_{1/3}MnO_{3}$ that suggests a new approach to this problem. We find that a rotational mode of the MnO$_6$ octahedra in $\bf La_{2/3}Ca_{1/3}MnO_{3}$ experiences pronounced superconductivity-induced lineshape anomalies, which scale linearly with the thickness of the $\bf YBa_2 Cu_3 O_7$ layers over a remarkably long range of several tens of nanometers. The transfer of the electron-phonon coupling between superlattice layers can be understood as a consequence of long-range Coulomb forces in conjunction with an orbital reconstruction at the interface. The superlattice geometry thus provides new opportunities for controlled modification of the electron-phonon interaction in complex materials.Comment: 13 pages, 4 figures. Revised version to be published in Nature Material

Spin-Charge-Lattice Coupling through Resonant Multi-Magnon Excitations in Multiferroic BiFeO3

Spin-charge-lattice coupling mediated by multi-magnon processes is demonstrated in multiferroic BiFeO3. Experimental evidence of two and three magnons excitations as well as multimagnon coupling at electronic energy scales and high temperatures are reported. Temperature dependent Raman experiments show up to five resonant enhancements of the 2-magnon excitation below the Neel temperature. These are shown to be collective interactions between on-site Fe d-d electronic resonance, phonons and multimagnonsComment: 11 pages including figure