Effect of hydration on conductivity of Ba4La x Ca2-X Nb2O11 + 0.5x (x = 0.5, 1, 1.5, 2) phases

Substitution of Ca by La in initial cubic double perovskite Ba 4(Ca2Nb2)O11[VO]1 allowed obtaining phases with a similar structure with a lower content of structural oxygen vacancies, Ba4(La x Ca2-x Nb 2)O11 + 0.5x [VO]1-0.5x (x = 0.5, 1, 1.5, 2). The impedance technique was used to measure the temperature dependences of conductivity in the atmosphere of dry and humid air. Transport numbers determined using the EMF method in an oxygen-air and water steam concentration cells point to the predominantly hole nature of conductivity in the high-temperature region (T > 600 C) and to predominance of proton conductivity in the low-temperature region. Activation energies of hole and proton conductivity were calculated. Thermogravimetric measurements were carried out under heating from 25 to 1000 C with simultaneous mass-spectrometric determination of evolved H2O and CO2. The properties of the studied Ba4(La x Ca2-x Nb 2)O11 + 0.5x (x = 0.5, 1, 1.5, 2) phases were compared with the earlier studied Ba4-x La x (Ca2Nb 2)O11 + 0.5x phases with similar lanthanum content. © 2013 Pleiades Publishing, Ltd

Novel Nb5+-doped hexagonal perovskite Ba5In2Al2ZrO13 (structure, hydration, electrical conductivity)

The new phase Ba5In2Al2Zr0.9Nb0.1O13.05 with hexagonal perovskite structure was obtained. The substitution of Zr4+ by smaller Nb5+ was accompanied by the incorporation of the oxygen interstitials and did not lead to a significant change in the lattice parameters. It was established that the investigated sample was capable for water incorporation from the gas phase, the hydration degree value was 0.24 mol H2O. IR-spectroscopy analysis defined the presence of OH−-groups with different thermal stability, which participate in different hydrogen bonds. The new phase Ba5In2Al2Zr0.9Nb0.1O13.05 demonstrates the predominant protonic conductivity at pH2O = 2·10−2 atm and Т600 °C

HYDRATION AND ELECTROCONDUCTIVITY OF THE DOPED BaLA2In2O7

Phases BaLa2In2O7 and Ti-, Zr-, Nb-substituted solid solutions was synthesized by solid state route as potential protonic conductors. Hydration of BaLa2In2O7 was measured by ther-mogravimetry in wet nitrogen atmosphere under heating and cooling. The degree of hydration for BaLa2In2O7 rise to 0,2

DEVELOPMENT OF SYNTHESIS METHODS AND INVESTIGATION OF PROPERTIES OF PEROVSKITES BASED ON CeAlO3

This article is devoted to the development of the solid state and solution combustion synthesis method and investigation of the properties of perovskite compounds based on CeAlO3. Structure, phase stability, conductivity and thermal expansion have been investigated

SYNTHESIS, THERMAL AND CONDUCTIVITY PROPERTIES OF PEROVSKITES BASED ON CeAlO3

This article is devoted to the development of the synthesis method and investigation of properties of perovskite like compounds based on CeAlO3. Structure, phase stability and con-ductivity have been investigated

COMPOSITE ELECTROLYTIC MATERIALS BASED ON LAMOX FAMILY

An improvement of electric properties of oxygen-ionic conductor La2Mo2O9 by addition of La2Ti2O7 heterogeneous dopant is studied. It is shown that the total conductivity of the composite sample increases in a wide temperature interval due to a special character of a microstructure of the composite

The ^4He trimer as an Efimov system

We review the results obtained in the last four decades which demonstrate the Efimov nature of the $^4$He three-atomic system.Comment: Review article for a special issue of the Few-Body Systems journal devoted to Efimov physic

A Strawberry KNOX Gene Regulates Leaf, Flower and Meristem Architecture

The KNOTTED-LIKE HOMEODOMAIN (KNOX) genes play a central role in maintenance of the shoot apical meristem. They also contribute to the morphology of simple and compound leaves. In this report we characterize the FaKNOX1 gene from strawberry (Fragaria spp.) and demonstrate its function in trasgenic plants. The FaKNOX1 cDNA was isolated from a cultivated strawberry (F.×ananassa) flower EST library. The sequence is most similar to Class I KNOX genes, and was mapped to linkage group VI of the diploid strawberry genome. Unlike most KNOX genes studied, steady-state transcript levels were highest in flowers and fruits. Transcripts were also detected in emerging leaf primordia and the apical dome. Transgenic strawberry plants suppressing or overexpressing FaKNOX1 exhibited conspicuous changes in plant form. The FaKNOX1 RNAi plants presented a dwarfed phenotype with deeply serrated leaflets and exaggerated petiolules. They also exhibited a high level of cellular disorganization of the shoot apical meristem and leaves. Overexpression of FaKNOX1 caused dwarfed stature with wrinkled leaves. These gain- and loss-of-function assays in strawberry functionally demonstrate the contributions of a KNOX domain protein in a rosaceous species

The Helicobacter pylori Genome Project : insights into H. pylori population structure from analysis of a worldwide collection of complete genomes

Helicobacter pylori, a dominant member of the gastric microbiota, shares co-evolutionary history with humans. This has led to the development of genetically distinct H. pylori subpopulations associated with the geographic origin of the host and with differential gastric disease risk. Here, we provide insights into H. pylori population structure as a part of the Helicobacter pylori Genome Project (HpGP), a multi-disciplinary initiative aimed at elucidating H. pylori pathogenesis and identifying new therapeutic targets. We collected 1011 well-characterized clinical strains from 50 countries and generated high-quality genome sequences. We analysed core genome diversity and population structure of the HpGP dataset and 255 worldwide reference genomes to outline the ancestral contribution to Eurasian, African, and American populations. We found evidence of substantial contribution of population hpNorthAsia and subpopulation hspUral in Northern European H. pylori. The genomes of H. pylori isolated from northern and southern Indigenous Americans differed in that bacteria isolated in northern Indigenous communities were more similar to North Asian H. pylori while the southern had higher relatedness to hpEastAsia. Notably, we also found a highly clonal yet geographically dispersed North American subpopulation, which is negative for the cag pathogenicity island, and present in 7% of sequenced US genomes. We expect the HpGP dataset and the corresponding strains to become a major asset for H. pylori genomics