The possibility of controlling the electrostatic field distribution in plasma has yielded wide prospects for modern technologies. As a magnetic field primarily allows for creating electric fields in plasma, it serves as an additional obstacle for the current flow through a medium. In the present paper, an axially symmetric system is considered in which the magnetic field is directed along the axis and concentric electrodes are located at the ends. The electrodes are negatively biased. A model which solves the problem of the radial distribution of the plasma potential inside the cylindrical plasma column supported by the end electrodes is proposed. The most commonly encountered configurations of the electrical connection for the end electrodes are considered, and the particular solutions to the problem of the radial distribution are presented. The contribution of ions and electrons to the transverse conductivity is evaluated in detail. The influence of a thermionic element on the radial profile of the plasma potential is considered. To verify the proposed model, an experimental study of the reflex discharge is carried out with both cold electrodes and a thermionic element on the axis. A comparison of the computational model results with experimental data is given. The presented model makes it possible to solve the problem concerning the plasma potential distribution in the case of an arbitrary number of end electrodes, and also to take into account the inhomogeneity of the distribution of plasma density, neutral gas pressure and electron temperature along the radius.

Metchnikovellids are a deep-branching group of microsporidia, parasites of gregarines inhabiting the alimentary tract of polychaetes and some other invertebrates. The diversity and phylogeny of these hyperparasites remain poorly studied. Modern descriptions and molecular data are still lacking for many species. The results of a light microscopy study and molecular data for Metchnikovella spiralis Sokolova et al., 2014, a hyperparasite of the eugregarine Polyrhabdina sp., isolated from the polychaete Pygospio elegans, were obtained. The original description of M. spiralis was based primarily on the analysis of stained preparations and transmission electron microscopy images. Here, the species description was complemented with the results of in vivo observations and phylogenetic analysis based on the SSU rRNA gene. It was shown that in this species, free sporogony precedes sac-bound sporogony, as it occurs in the life cycle of most other metchnikovellids. Spore sacs are entwined with spirally wound cords, and possess only one polar plug. Phylogenetic analyses did not group M. spiralis with M. incurvata, another metchnikovellid from the same gregarine species, but placed it as a sister branch to Amphiacantha. The paraphyletic nature of the genus Metchnikovella was discussed. The taxonomic summary for M. spiralis was emended.

The paper investigates trace elements and crystal-rich fluid inclusions in spodumene from rare-metal pegmatites of the Kolmozero lithium deposit in the Kola region, Russia. The main lithium mineral in the pegmatites is spodumene, which occurs in three generations, designated as Spd-I, Spd-II and Spd-III. Iron, Na and Mn are the most typical element impurities in spodumene. The Fe/Mn ratio is 7.1 in Spd-I, 12.3 in Spd-II and 13.2 in Spd-III. Spd-II contains fluid and crystal-rich fluid inclusions. The crystal-rich fluid inclusions in Spd-II originally trapped CO2-bearing aqueous fluids with dissolved alkali carbonates. The crystal-rich fluid inclusions contain zabuyelite (Li2CO3) and cristobalite (SiO2) as solid phases, which have not been reported previously from the Kolmozero rare-metal pegmatites. These minerals are assumed to have resulted from a reaction between a CO2-bearing aqueous fluid and host Spd-II and are not related to the mineral-forming system of pegmatites.

The recent 2014–2017 controlled excavations carried out in quarries of Sverdlovsk and Tyumen regions, Ural and Western Siberia, are contributing to the knowledge of the middle to late Eocene marine fauna from the Turgay Strait, mainly composed of invertebrates and cartilaginous and bony fishes. Here we present a preliminary report of the bony fishes collected during the campaigns carried out in two Eocene Trans-Urals localities. The sediments of these localities were deposited in a large epicontinental marine basin during the middle to late Eocene, when the Turgay Strait connected the Arctic waters to the North and the Peritethys to the South. Most of the bony fish material examined can be assigned to codfishes (Gadiformes) according to morphological comparison with living and fossil taxa. In particular, nearly complete three-dimensionally preserved lower jaws are confidently assigned to the Merlucciidae, whereas isolated vertebrae and bones are referred to as Gadiformes incertae sedis. This report documents the easternmost occurrence of this group of fishes in the northern hemisphere during the early phases of their radiation, revealing their presence into the Turgay Strait before its closure.

A technique has been developed for determining coefficients in the power approximation of the “stress–strain” diagram by results of scratch testing with a Berkovich indenter under a normal load of 5 mN on the indenter. The procedure is based on a comparison of experimental results with the finite element simulation of the test process. The technique is intended for application on nanomechanical testing equipment enabling one to perform tests with recording of loading diagrams in terms of the “normal force – indenter displacement” coordinates. To obtain correct results, one must observe the following restrictions: indenter penetration depth > 150 nm under a loading of 5 mN with the indenter tip curvature radius R < 50 nm; indenter penetration depth > 250 nm with 50 < R < 100 nm; the tested metal must be ductile enough, for a scratch to be formed by the mechanism of plastic deformation rather than fracture.

The present paper reports results of a transmission electron microscopy study of a new metchikovellid microsporidium. It was isolated from gregarines Polyrhabdina sp. inhabiting guts of polychaetes Pygospio elegans sampled at the White Sea silt littoral zone. Free sporogony (FS) occurred in the life cycle of the microsporidium alongside sac-bound sporogony (BS). Free spores resided in a parasitophorous vacuole and were of typical metchnikovellidean structure, uninucleate and oblong. They measured on sections 2·0–3·2×1·3–1·9 μm. The life cycle included pre-sporogonial stages represented by dikaryotic cells and 4-nucleate cells with coupled nuclei. A multinucleate sporogonial plasmodium of FS split in numerous (>10) sporoblasts. In BS segregation of sporoblasts occurred within thick-walled cysts by internal budding. Spore sacs of this microsporidium, measuring on average 11·6×4·7 μm, were limited by a thick electron-dense wall, externally ornamented with spirally wound cords of dense material. These oval spore sacs contained eight barrel-shaped spores, comparable in size and ultrastructure to FS spores. Ultrastructure of both types of spores and intracellular development of the new microsporidium and Metchnikovella spp. were similar, suggesting they belong to the same genus. In this paper we describe a new species Metchnikovella spiralis and discuss morphology of metchnikovellids in the context of putative evolutionary history of Microsporidia.

Class Rudimicrosporea Sprague 1977, with its single family Metchnikovellidae, comprises hyperparasites of gregarines from the guts of marine invertebrates. Metchnikovellids remain poorly studied in spite of their significance to the evolutionary history of microsporidia; their ultrastructure and life cycles require further investigation. Here we present results of the light- and electron-microscopy study of Metchnikovella incurvata Caulleri and Mesnil 1914, isolated from lecudinid gregarines, parasitizing polychaetes Pygospio elegans in the White Sea littoral zone, and yet described only on the light-microscopic level. The life cycle of this microsporidium includes 2 sporogonies: free (FS) and sac-bound (SBS). In FS, sporonts develop into multinuclear cells (sporogonial plasmodia), which generate sporoblasts and free spores residing in direct contact with the host cytoplasm. Electron microscopy revealed their metchnikovellidean structure: a horseshoe-shaped nucleus, short manubrium perpendicular to the long axis of the spore, and a polar cap in a separate membrane container. Merogony was not observed. The earliest stages of SBS were chains of binucleate cells. They underwent a series of nuclear and cell divisions, produced extracellular envelopes, and split into boomerang-shaped spore sacs, containing up to 16 spores each. Ultrastructure and sizes of sac-bounded spores were similar to those of free-living ones. An amended diagnosis of M. incurvata is provided.

To counteract plasma instabilities like Neoclassical Tearing Modes (NTM-modes) in nuclear fusion reactors (JET, ITER, DEMO) high power microwaves are used for the Electron Cyclotron Resonance Heating (ECRH) and for the plasma current drive (CD). The foreseen power level for ITER (Cadarache, France) is Ptot = 24 MW at f = 170 GHz. Each transmission line is designed for a maximum of 2 MW power. The vacuum and tritium barrier to the ITER vacuum vessel is realized by a CVD diamond disk window assembly. Diamond has an extremely high thermal conductivity of about k = 2100 W/Km and a very low loss tangent of tan δ < 10-5 for this frequency and shows therefore a very small microwave absorption. The normalized absorbed power A=Pabs/P0 can be calculated as A = (f/c) • π • (1+εr‘) • tan δ • t (with the rule of thumb estimate: (f/c)=0.5 mm-1; π • (1+εr‘) = 20; tan δ =10-5; A=10-4 • t [mm]); i.e. each t = 1 mm thickness of diamond absorbs Pabs = 100 W of Po = 1 MW microwave power transmitted through the CVD diamond window with an effective tanδ of 10-5.

K–Ar measurements of the Chotanagpur granite and associated intrusive rocks are found to be younger than the geological events in the Singhbhum region of Bihar. The history of metamorphism, granitic activities and igneous intrusions in the Chotanagpur area continued for a period from over 1000 Ma to 185 Ma. The relevant geological sequences and correlations are briefly discussed.

The plasma temperature in a new plasma source shows unusual behaviour at low pressures (about 1 mTorr) and high absorbed powers. In Ar plasma at pressures of about 1 mTorr, the electron temperature shows a pronounced maximum inside an electromagnetic accelerator, which is followed by a rapid drop at the boundary between the accelerator region and the main chamber. In this paper a neoclassical thermo-conductivity model based on the analysis of the electron trajectories is proposed to describe the sharp electron temperature profile. Quantitative agreement of the calculated temperature profile with the experiment is observed.

Effects of 10 MeV electron and fast reactor neutron irradiations on carrier removal rate and deep traps spectra were compared for undoped n-GaN samples. It is shown that for electron irradiation the carrier removal rate is well accounted for by the difference in introduction rates of nitrogen-vacancy-related donors with activation energy 0.2 eV and of nitrogen-interstitial-related acceptors at Ec-1.2 eV. In the case of neutron irradiation the introduction rate of all deep traps was much lower than the carrier removal rate indicating that the main contribution to electron removal was due to disordered regions. These regions give rise to a marked persistent photocapacitance signal and a hole-trap-like feature in deep traps spectra. The Fermi level position in the core of disordered regions is located near Ec-(0.85-1) eV.

Effects of 10 MeV electron and fast reactor neutron irradiations on carrier removal rate and deep traps spectra were compared for undoped n-GaN samples. It is shown that for electron irradiation the carrier removal rate is well accounted for by the difference in introduction rates of nitrogen-vacancy-related donors with activation energy 0.2 eV and of nitrogen-interstitial-related acceptors at Ec-1.2 eV. In the case of neutron irradiation the introduction rate of all deep traps was much lower than the carrier removal rate indicating that the main contribution to electron removal was due to disordered regions. These regions give rise to a marked persistent photocapacitance signal and a hole-trap-like feature in deep traps spectra. The Fermi level position in the core of disordered regions is located near Ec-(0.85-1) eV.

The nonuniform temperature distribution in a crystal surface during ultrasonic loading has been detected. This effect was associated with a sonic-stimulated temperature rise around dislocations and heating of the nonperfect regions of the samples investigated. The dislocation moved in an ultrasonic field was considered as a linear thermal source. We calculated the temperature distribution around dislocations and determined conditions of the discrete and continuous distribution of thermal sources for Hg $_{1-x}$ Cdx Te alloys. We also discuss the possibility of using the investigated effect as the basis of a non-destructive technique for extended defect mapping and imaging in crystals.

Photoluminescence and electrical measurements were carried out for studying the influence of rare-earth elements (Yb) concentration in the Ga melt on the electronic and structural properties of LPE GaAs epilayers. It was shown that at low concentration the main role of Yb is the gettering of residual impurities in the melt. At the same time, Yb addition in the melt changes the heterogeneous equilibrium by changing the stoichiometry of epilayers (increase of $V_{\text{Ga}}$ ). But at further increase of Yb concentration in the melt Yb begins to enter in the Ga-sublatticeand cluster with deviation from the stoichiometry. An optimum concentration of Yb exists at which high-purity and stoichiometric epilayers for a device application can be obtained.

Over the past 15 years, Japanese, Australian and Russian expeditions to Prydz Bay have collected about 30 000 km of bathymetric data, 6000 km of sidescan sonar data and more than 250 sediment grab and core samples. These data were used in the present study to compile surficial sediment, bathymetric, and geomorphological maps of the Prydz Bay region. Lithofacies distribution was determined by surficial sediment data analysis using sample matrix (Q-mode) and cluster analysis techniques based on data from 206 sites. Data included percentage biogenic silica (opal), calcium carbonate, gravel, mud, and relative abundance of two diatom species (Fragilariopsis curta and F. kerguelensis). Five lithofacies are identified from the available data: (1) slightly gravelly sandy mud (g)sM lithofacies, (2) siliceous mud and diatom ooze (SMO) lithofacies, (3) F. kerguelensis pelagic ooze lithofacies, (4) F. curta gravelly muddy sand gmS lithofacies and (5) calcareous gravel lithofacies. In many areas the lithofacies correlate to geomorphological provinces as defined by previous investigators using 3.5 kHz and sidescan sonar data. In some cases, Holocene SMO sediments are seen to drape over iceberg plough marks, implying that these are relict features. These five lithofacies are likely to dominate most of the East Antarctic shelf region and may be helpful in defining sedimentary successions resulting from ice-sheet advance and retreat over glacial-interglacial cycles.

Films deposited by the Hot Wire CVD method were studied by means of dark conductivity, FTIR, Hydrogen Evolution, SEM and AFM surface characterization. Three types of metastability were observed: a) long term irreversible degradation due to oxidization processes on the film surface, b) reversible degradation determined by uncontrolled water adsorption, c) fast field switching effect in the film bulk.

Oxygen and hydrogen content and its bonding configurations have been analyzed by hydrogen evolution and infrared spectroscopy methods on the films deposited on glass substrates and silicon wafers subsequently. It has been found that metastable processes close to the film surface are stronger than in the bulk. The switching effect is the fast increase of charge carrier density observed on bottom chromium contacts under a condition of air admittance. We propose this effect is associated with morphology changes during film growth and electrical field induced by adsorbed atmospheric components on the film surface.

In this paper, the results of experiments on irradiation of the singlewall (SWNT) and multiwall carbon nanotube (MWNT) samples by argon ions are presented. They were obtained by reflection electron energy loss spectroscopy and Auger electron spectroscopy.

Results indicate the π-plasmon energy E π and the full width at half maximum (FWHM) of the plasma peak were sensitive to the dose of ion irradiation. In particular, the π-plasmon energy E π decreases and the plasma peak broadens with the increase of the dose of Ar+irradiation.

The π-plasmon peak broadening is associated with damage of carbon nanotubes under ion irradiation. Possible causes of the carbon nanotubes deformation and influence of deformation on π-band structure of carbon nanotubes are discussed.

A study of the effects of light-soaking and atmospheric adsorption (aging) on the dark- and photo-conductivity of a series of microcrystalline silicon films of varying crystallinity is presented. Light-soaking in vacuum slightly reduces photoconductivity in films close to the amorphous – microcrystalline transition, and there is also a reduction in dark current. Aging increases the dark current, and thus unless due care is taken during light-soaking experiments to eliminate or compensate for aging, the apparent effect of light-soaking may be reduced or even reversed in sign. Transient photocurrent decays confirm the presence of a large density of metastable light-induced defects. A shift in the apparent distribution of defects occurs on prolonged aging, which may be due either to changes in the DOS or a shift in the Fermi level.