207Pb and 17O NMR Study of the Electron Density Distribution in Metal Phase of BaPb_{1-x}Bi_xO_3

The 17O and 207Pb NMR spectra were measured in ceramic samples in the metallic phase of BaPb_{1-x}Bi_{x}O_3 oxides (0<x< 0.33). The inhomogeneous magnetic broadening which appears due to a distribution of the Knight shifts was analyzed in detail. It is shown that Bi atoms, which are randomly incorporated in BaPbO_3 parent compound give rise to an increased conduction electron spin density within an area which is delimited by its two first cation shells. According to NMR data the percolative overlap of these areas occurs in superconducting compositions and it is accompanied by a sharp growth of the average Knight shift . The decrease of with temperature revealed for x=0.33 evidences for an opening of the energy gap near E_F near the metal-semiconductor transition (x=0.35).Comment: submitted to Phys. Rev.

Hydrothermal alteration mapping of Siberian gold-ore fields based on satellite spectroscopy data

The mapping of the hydrothermal alterations in Urjahskoe and Fedorov-Kedrov gold-ore fields was conducted by applying channel relationship method (band ratio) based on ASTER spectral-zonal satellite image data. It was determined that the calculated mineral indices in ore-bearing structures are zonal. Outer ore-bearing structures revealed increased ferric mineral index values, while inner - high epidote- chlorite- calcite and muscovite- siderite mineral index values. Detected regularities could be used in identifying potential gold-ore bearing areas within identical fields based on remote sensing survey data

Guaranteed Estimation Problem for Multi-Step Systems

Questions of the guaranteed estimation of nonlinear multistep systems are considered, for which part of coordinates is not observable. For disturbances we set a priori restrictions with non-negative semi-continuous functions that includes geometrical restrictions as well. As the general formulas for creation of information sets and their specification in special cases are provided. Two-dimensional logistics systems and the equations of Lotka-Volterra are considered as examples. The case of the linear equations where basic functions of convex sets are used is separately considered. Under geometrical restrictions on disturbances the rough procedure of estimation with possible use of functions of distance to the set is given

About an Estimation Problem of a Linear System with Delay of Information

The problem of guaranteed estimation with geometrically bounded initial states and integrally limited disturbances is considered under delay information in the measurement equation. At the additional assumptions the problem is reduced to the creation of the reachable set of a special system. A discrete multistage system is specified for which the information set converges in Hausdorff’s metric to the corresponding information set of the continuous system when the diameter of partition is reduced. A numerical example is given

Cosmostructural model of the Kalgutinskiy rare-metal deposit area (Mountainous Altai)

Cosmostructures of the Kalgutinskiy rare-metal deposit area (Mountainous Altai) have been studied on the materials of multispectral space survey Landsat ETM+ and radar-tracking survey SRTM. The area is localized inside of the large ring structure of a complex construction, characterized by the long multistage (multipulse) development. Immersing of the root (focus) part of the structure from the north - northwest to the east - southeast is established. Position of the ring structure is controlled by the crossing knot of fracture zones of northwest, northeast and northeast - sublatitudinal directions. The Kalgutinskiy granite massif and the deposit itself are located in the internal belt of the structure in the ring 15,2 km in diameter. The perspective of ore-bearing ability of the southeast part of the area is highly evaluated in connection with development of small ring structures of the second typ

Rate‐determining steps of oxygen surface exchange kinetics on Sr2Fe1.5Mo0.5O6−δ

The oxygen surface kinetics of Sr2Fe1.5Mo0.5O6−δ was determined using the 16O2/18O2 isotope exchange method with gas phase analysis at 600-800 °C. The heterogeneous exchange rates (rH) and the oxygen diffusion coefficients (D) were calculated by processing the concentration dependences of the 18O fraction using Ezin's model. The rates of oxygen dissociative adsorption (ra) and incorporation (ri) were calculated based on a model using the three exchange type rates. It has been established that the rates ra and ri were comparable in this temperature range. Assumptions were made about the effect of the chemical composition of the surface on the rate of oxygen adsorption. It was found that the oxygen exchange coefficient (k) of Sr2Fe1.5Mo0.5O6−δ is comparable to that of La0.6Sr0.4MnO3±δ oxide. High values of the oxygen diffusion coefficient were found for Sr2Fe1.5Mo0.5O6−δ. The values were comparable to those of the double cobaltite praseodymium-barium and exceed by more than an order those of lanthanum‐strontium manganite. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Russian Foundation for Basic Research, RFBR: 00161Government Council on Grants, Russian FederationThe study was partly financially supported by the Russian Foundation for Basic Research (17-08-00161) and the Russian Federation Government, agreement 02.A03.21.0006 (no. 211)

Water uptake and transport properties of La1-xCaxScO3-α proton-conducting oxides

In this study, oxide materials La1-xCaxScO3-α (x = 0.03, 0.05 and 0.10) were synthesized by the citric-nitrate combustion method. Single-phase solid solutions were obtained in the case of calcium content x=0.03 and 0.05,whereas a calcium-enriched impurity phasewas found at x=0.10. Water uptake and release were studied by means of thermogravimetric analysis, thermodesorption spectroscopy and dilatometry. It was shown that lower calcium content in the main phase leads to a decrease in the water uptake. Conductivity wasmeasured by four-probe direct current (DC) and two-probe ascension current (AC)methods at different temperatures, pO2 and pH2O. The effects of phase composition,microstructure and defect structure on electrical conductivity, as well as correlation between conductivity and water uptake experiments, were discussed. The contribution of ionic conductivity of La1-xCaxScO3-α rises with decreasing temperature and increasing humidity. The domination of proton conductivity at temperatures below 500 °C under oxidizing and reducing atmospheres is exhibited. Water uptake and release as well as transport properties of La1-xCaxScO3-α are compared with the properties of similar proton electrolytes, La1-xSrxScO3-α, and the possible reasons for their differences were discussed. © 2019 by the authors.Russian Science Foundation, RSF: 16-13-00053Government Council on Grants, Russian FederationMinistry of Education and Science of the Republic of KazakhstanFunding: The research was partially supported by the Russian Science Foundation (Grant №16-13-00053) and the Ministry of Education and Science of the Republic of Kazakhstan (Project No. AP05130148). The education activity of Ph.D. and students involved into this work is supported by Act 211 of Government of the Russian Federation, agreement No. 02.A03.21.0006