Барьеры для инжекции электронов и дырок из подложки кремния в ВЧ-магнетронно напыленные пленки In2O3 : Er

The In2O3 : Er films were deposited on Si substrates by the RF magnetron sputtering technique. For the Si substrates of both n- and p-type the current through the MOS-structure (Si/In2O3 : Er/In-contact) was described by the thermionic emission of the main currents over the barrier, with the correction of the applied voltage into the partial voltage drop in silicon. By the temperature dependence measurements of the forward currents at small under-barrier biases the barriers for the current injection from Si into the films were found equal to the 0.14 eV and 0.3 eV for the electrons and holes accordingly. The obtained small barrier for the holes is described by the presence of the defect state density. It tails from the valence band maximum into the In2O3 : Er band gap and provides there the conduction channel for holes. The defect state density in the In2O3 : Er band gap is proved by the PL data in the respective energy range 1.55–3 eV. The band analysis for the hetero-structure Si/In2O3 : Er is performed. It gives the energy gap between the electrons in the In2O3 : Er conduction band and the holes in the band gap channel equal to the 1.56 eV.Пленки In2O3 : Er были напылены на подложки кремния с помощью ВЧ-магнетронного распыления-осаждения. Для подложек кремния как n-, так и p-типа проводимости токи через полученные МОП-структуры (Si/In2O3 : Er/In-контакт) были описаны в рамках модели термоэмиссии основных носителей через барьер с коррекцией приложенного напряжения на потенциал, падающий в кремнии. С помощью измерения температурной зависимости прямых токов при малом, подбарьерном смещении были найдены барьеры для инжекции электронов и дырок из кремния в пленки, равные 0,14 и 0,3 эВ, соответственно. Полученный невысокий барьер для дырок объясняется наличием плотности дефектных состояний, которые простираются от края зоны валентности в запрещенную зону In2O3 : Er и создают там канал проводимости для дырок. Наличие плотности дефектных состояний в запрещенной зоне In2O3 : Er подтверждается данными фотолюминесценции в соответствующем интервале энергий 1,55—3,0 эВ. Выполнен анализ зонной структура гетероперехода Si/In2O3 : Er. На его основе установлен энергетический интервал между электронами в зоне проводимости In2O3 : Er и дырками в канале проводимости в запрещенной зоне, равный 1,56 эВ.

Long-term dynamics of hydrological conditions of the Zelenetskaya Bay, East Murman

The features of the oceanographic regime of the Zelenetskaya Bay have been investigated. It is one of the East Murman bays that occupies an important place in the economic history of the Kola Peninsula coastal zone and in the creation of the outpost of the academic science in the West Arctic. The data of long-term observations have been generalized and the average meteorological and hydrological parameters of this basin for the last decade have been presented. The presented results are of practical importance for developing aquaculture in the bay, for formation of marine economics infrastructure including the recreation branch and for the fundamental experimental researche

The Effects of Alkylhydroxybenzenes on Homoserine Lactone-Induced Manifestations of Quorum Sensing in Bacteria

The effects of four alkylhydroxybenzene (AHB) homologs with different hydrocarbon chain lengths on the synthesis of violacein pigment induced by C6-homoserine lactone (HSL) and biofilm formation by Chromobacterium violaceum NCTC 13274 and on Escherichia coli pAL103 bioluminescence in the presence of C6-oxo-HSL were studied. Alkylhydroxybenzenes inhibit the growth of C. violaceum increased in the C5-AHB → C12-AHB series in the absence of this activity in C1-AHB. Subinhibitory AHB concentrations reduced violacein production and suppressed biofilm formation. These effects were presented as individual and group regression dependencies between the analysed parameters. Using the bioluminescent model, the regulatory effects of AHBs were not associated with their direct competition with HSL and that they develop as a result of changes in the sensitivity of bacterial cells to the respective quorum sensing inducer

Arp GENE NUCLEOTID SEQUENCES VARIABILITY IN RUSSIAN TREPONEMA PALLIDUM ISOLATES

Aim. Analysis of the arp gene internal fragment nucleotide sequences variability in modern russian T. pallidum subsp. pallidum strains. Materials and methods. 57 T. pallidum isolates obtained from specialized dermatovenerologic clinics of the Central (Kaluga), the North Caucasus (Stavropol) and the Siberian (Tyva) regions in 2016 — 2017 were used in the study. The sequensing of the arp gene was performed using capillary electrophoresis technology. Results. A two-round amplification of the arp gene have been proposed, which ensures a correct reading of its internal region. Four variants of 60-nucleotide repeats in the internal arp fragment are described, which differing in 6, 8 and 15 — 17 codons compositions. Various combinations of these repeats, corresponding to the reference Nichols strain, globally distributed Street 14 genogroup, and the firstly described Stavropol regional variant are shown. Conclusion. The prospect of arp gene sequencing as a way to increase T. pallidum molecular typing efficiency is postulated

NG-MAST GENOTYPING OF NEISSERIA GONORRHOEAE STRAINS ISOLATED IN RUSSIAN FEDERATION IN 2012 - 2015

Aim. Characteristics of contemporary strains of N. gonorrhoeae using NG-MAST genotyping (.Neisseria gonorrhoeae multi-antigen sequence typing), isolation of dominating variants and analysis of their territorial distribution. Materials and methods. 440 strains of N. gonorrhoeae isolated in 2012 - 2015 in 19 subjects of the Russian Federation were used in the study. Genotyping was carried out based on sequencing of variable regions of porB and tbpB genes. Identification of alleles and sequence-types was carried out according to http://www.ng-mast.net. Results. 172 NG-MAST genotypes were identified, 100 of which -were described for the first time. 807,1152, 1544,5714 and 5941 were predominating sequence-types, typical for several subjects of the Russian Federation and some neighboring countries, as well as sequence-types 8583 and 9476 described for the first time, that were exclusively distributed in the regions of their emergence. Sequence-types 225, 1407 and 2992, that are epidemically significant in distant countries, were represented by single isolates in this study. Conclusion. A peculiar and significant genetic diversity of N. gonorrhoeae strains, circulating in the Russian Federation, with characteristic bond of several NG-MAST genotypes to one or several regions, was shown

Toxicity of Carbon Based Nanomaterials against Escherichia coli Depends on Dispersion Efficacy of Their Water Suspensions

The relationships between surface wettability, dispersion efficacy in water suspensions and biotoxicity of nine carbon_based nanomaterials (CBN) samples represented by nanotubes, nanofibres and fullerenes are established. It is shown that presence of polar groups on the surface of similar in structure CBNs increases their hydrophilicity, reduces the particles size in water suspensions, and manifests itself by growth of the toxicity level in the luminescent screening assay based on Escherichia coli with the cloned luxCDABEgenes Photobacterium leiognathi. The artificial increase in individual CBN dispersion efficacy by primary suspension in the aprotic solvent dimethyl sulfoxide with the following transfer into an aqueous environment, also has led to growth of the registered biological activity. At the same time, the dispersion efficacy of morphologically diverse CBN is not the main cause of distinctions in their biotoxicity

Investigation of Copper Nanoparticles Antibacterial Mechanisms Tested by Luminescent Escherichia coli Strains

The electrostatic interaction between positively charged copper nanoparticles aggregates (ζ =+15.9 ± 8.63 mV) and negatively charged surface of E. coli K12 TG1 cells (ζ = –50.0 ± 9.35 mV) has been established. The time_dependent decline of bacterial cells zeta potential and the coupled inhibition of constitutive bioluminescence level are the results of this interaction. The development of oxidative stress, probably defined by the electron transfer from the cytoplasmic membrane respiratory chains through membraneintegrated copper nanoparticle to the molecular oxygen, is shown as luminescence induction in superoxideand peroxide_inducible E. coli K_12 MG1655 pSoxS::lux and pKatG::lux reporter strains. The final result of this process, which is responsible for the development of the bactericidal effect of copper nanoparticles, is DNA damage by active oxygen species detected by SOS_inducible E. coli pRecA::lux luminescent strain