Search for Cooper-pair Fluctuations in Severely Underdoped YBCO Films

The preformed-pairs theory of pseudogap physics in high-$T_C$ superconductors predicts a nonanalytic $T$-dependence for the $ab$-plane superfluid fraction, $\rho_S$, at low temperatures in underdoped cuprates. We report high-precision measurements of $\rho_S(T)$ on severely underdoped YBa$_2$Cu$_3$O$_{6+x}$ and Y$_{0.8}$Ca$_{0.2}$Ba$_2$Cu$_3$O$_{6+x}$ films. At low $T$, $\rho_S$ looks more like $1 - T^2$ than $1 - T^{3/2}$, in disagreement with theory.Comment: 3 pages, 2 figure

Diameter Dependence of the Transport Properties of Antimony Telluride Nanowires

We report measurements of electronic, thermoelectric, and galvanomagnetic properties of individual single crystal antimony telluride (Sb2Te3) nanowires with diameters in the range of 20-100 nm. Temperature dependent resistivity and thermoelectric power (TEP) measurements indicate hole dominant diffusive thermoelectric generation, with an enhancement of the TEP for smaller diameter wires up to 110 uV/K at T = 300 K. We measure the magnetoresistance, in magnetic fields both parallel and perpendicular to the nanowire [110] axis, where strong anisotropic positive magnetoresistance behavior was observed

Optical models of the molecular atmosphere

The use of optical and laser methods for performing atmospheric investigations has stimulated the development of the optical models of the atmosphere. The principles of constructing the optical models of molecular atmosphere for radiation with different spectral composition (wideband, narrowband, and monochromatic) are considered in the case of linear and nonlinear absorptions. The example of the development of a system which provides for the modeling of the processes of optical-wave energy transfer in the atmosphere is presented. Its physical foundations, structure, programming software, and functioning were considered

A combined Raman lidar for low tropospheric studies

One of the main goals of laser sensing of the atmosphere was the development of techniques and facilities for remote determination of atmospheric meteorological and optical parameters. Of lidar techniques known at present the Raman-lidar technique occupies a specific place. On the one hand Raman lidar returns due to scattering on different molecular species are very simple for interpretation and for extracting the information on the atmospheric parameters sought, but, on the other hand, the performance of these techniques in a lidar facility is overburdened with some serious technical difficulties due to extremely low cross sections of Raman effect. Some results of investigations into this problem is presented which enables the construction of a combined Raman lidar capable of acquiring simultaneously the profiles of atmospheric temperature, humidity, and some optical characteristics in the ground atmospheric layer up to 1 km height. The operation of this system is briefly discussed

Investigation of GdBaCo2-xFexO6-δ (x = 0, 0.2) - Ce0.8Sm0.2O2 composite cathodes for intermediate temperature solid oxide fuel cells

The double perovskites GdBaCo2-xFexO 6-δ (x = 0, 0.2) and composites (100 - y) GdBaCo 2-xFexO6-δ (x = 0, 0.2) - y Ce 0.8Sm0.2O2 (y = 10-50 wt.%) were investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). Chemical compatibility of GdBaCo2-xFexO 6-δ (x = 0, 0.2) with solid electrolyte Ce0.8Sm 0.2O2, thermal expansion, DC conductivity and electrochemical performance of (100 - y) GdBaCo2-xFe xO6-δ (x = 0, 0.2) - y Ce0.8Sm 0.2O2 (y = 10-50 wt.%) were studied. Partial substitution of Fe for Co was shown to lead to decrease of double perovskite GdBaCo 2-xFexO6-δ reactivity with the solid electrolyte Ce0.8Sm0.2O2. Polarization resistance of cathodes studied was found to depend significantly on firing temperature. Variation of solid electrolyte content in (100 - y) GdBaCo 2-xFexO6-δ (x = 0, 0.2) - y Ce 0.8Sm0.2O2 (y = 10-50 wt.%) composites was shown to allow to optimize their electrochemical performance. Cathode materials of 80 wt.% GdBaCo2O6-δ - 20 wt.% Ce 0.8Sm0.2O2 and 65 wt.% GdBaCo 1.8Fe0.2O6-δ - 35 wt.% Ce 0.8Sm0.2O2 were found to have the lowest polarization resistances and reasonable values of thermal expansion coefficient (TEC) and, therefore, can be considered as promising cathode materials for IT-SOFCs. © 2013 Elsevier B.V. All rights reserved

Crystal structure and oxygen content of the double perovskites GdBaCo 2-xFexO6-δ

The iron solubility limit, x, in GdBaCo2-xFexO 6-δ determined by means of X-ray diffraction was found to be close to 0.65 in air. The crystal structure changes of the double perovskites GdBaCo2-xFexO6-δ (x=0-0.6) were studied by means of in situ X-ray diffraction in temperature range from 25 to 900 °C in air. The oxygen content, 6-δ, was determined for these double perovskites in air as a function of temperature by means of thermogravimetric technique in range 25≤T, °C≤ 1100. The Pmmm-P4/mmm structure transition was found to occur in GdBaCo2-xFexO 6-δ (0≤x≤0.4) with increasing temperature. This transition is observed at the same temperature for the compositions with 0≤x≤0.1 while the transition temperature reaches maximum for x=0.2 and that decreases linearly with further iron increase. The double perovskite GdBaCo1.4Fe0.6O6-δ was shown to have the tetragonal P4/mmm structure at room temperature. The P4/mmm-Pmmm structure transition occurs at temperature as low as 170 °C for this double perovskite while reverse one is already observed at 290 °C in air. The Pmmm-P4/mmm structure transition was found to be strongly related to the oxygen content for the undoped and slightly doped (x≤0.2) double perovskites while there is no such relation for the double perovskites enriched by iron (x≥0.2). © 2012 Elsevier Inc. All rights reserved

Interaction of Scots Pine Defensin with Model Membrane by Coarse-Grained Molecular Dynamics

© 2017, Springer Science+Business Media New York.Plant defensins are a part of the innate immune system of plants that acts against a broad range of pathogens. Many plant defensins, including pine defensins, show strong antifungal activity that is associated with their ability to penetrate into the fungal cell membrane. However, the exact molecular mechanism of their action remains poorly defined. To obtain insight into the mechanism of protein–membrane interaction, we applied a coarse-grained molecular dynamics simulation to study the interaction of pine defensin with two model membranes: the first consisted of zwitterion-neutral POPC molecules and the second was composed of combined anionic POPG and POPC. The simulations show that defensin does not form stable complexes with the neutral membrane but does interact with the combined POPG/POPC membrane. In the latter case, defensin attaches to the membrane surface by interacting with lipid polar heads without deep penetration into the hydrophobic tail zone. Electrostatic interactions are a driving force of the complex formation, which determines the orientation of the protein relative to the bilayer surface. Two favorable orientations of defensin are detected where the defensin molecule orients either perpendicular or parallel to the membrane plane. Being positively charged, pine defensin induces changes in the lipid distribution along the membrane, resulting in the formation of zones with different electrostatic potentials that can cause deformation or distortion of the membrane. Pine defensin is a representative of plant defensins, and hence the results of this study can be applied to other members of the family

The native monomer of bacillus pumilus ribonuclease does not exist extracellularly

Copyright © 2018 Olga Ilinskaya et al. Supported by crystallography studies, secreted ribonuclease of Bacillus pumilus (binase) has long been considered to be monomeric in form. Recent evidence obtained using native polyacrylamide gel electrophoresis and size-exclusion chromatography suggests that binase is in fact dimeric. To eliminate ambiguity and contradictions in the data we have measured conformational changes, hypochromic effect, and hydrodynamic radius of binase. The immutability of binase secondary structure upon transition from low to high protein concentration was registered, suggesting the binase dimerization immediately after translocation through the cell membrane and leading to detection of binase dimers only in the culture fluid regardless of ribonuclease concentration. Our results made it necessary to take a fresh look at the binase stability and cytotoxicity towards virus-infected or tumor cells