109 research outputs found

    Soil formation in technogenic landscapes: trends, results, and representation in the current classifications (Review)

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    For hundreds of years, humans have been a soil formation factor. With the recent industrial development of vast territories, the formation of soils in technogenic and postanthropogenic conditions requires more attention. This study reviews the literature on the soils of human-transformed or human-made landscapes (technogenic landscapes),in which soil formation starts on a new technogenic substrate. Such soils may occur in different bioclimatic conditions. We focused on processes that govern soil morphology and the subsequent transformation of these soils. Often, the soils of technogenic landscapes are characterized by high bulk density values and by the presence of dense contact. Their properties are affected mainly by organic matter accumulation (humus, litter, and peat). The paper also covers approaches to the reclamation of technogenic landscapes, the main stages, and partly the reclamation options. It is noted that the efficiency of reclamation activities depends on the available resources and timely decision-making. We assessed the efficiency of soil reclamation methods and suggested technogenic landscape survey techniques. The major approaches to soil classification in technogenic landscapes in national and international soil classification systems are briefly discussed, and an approximate correlation of soil names used in different systems is suggested. All considered classifications provide the opportunity to assess the soil properties and specifics of soil formation in technogenic landscapes. However, in most studies, the soil diagnostics are limited to top-order taxa only

    Quantum memory for images - a quantum hologram

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    Matter-light quantum interface and quantum memory for light are important ingredients of quantum information protocols, such as quantum networks, distributed quantum computation, etc. In this Letter we present a spatially multimode scheme for quantum memory for light, which we call a quantum hologram. Our approach uses a multi-atom ensemble which has been shown to be efficient for a single spatial mode quantum memory. Due to the multi-atom nature of the ensemble it is capable of storing many spatial modes, a feature critical for the present proposal. A quantum hologram has a higher storage capacity compared to a classical hologram, and is capable of storing quantum features of an image, such as multimode superposition and entangled quantum states, something that a standard hologram is unable to achieve. Due to optical parallelism, the information capacity of the quantum hologram will obviously exceed that of a single-mode scheme.Comment: 5 pages, 3 figure

    Sr Doping and Oxygen Vacancy Formation in La1−xSrxScO3−δ Solid Solutions: Computational Modelling

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    The study was performed with the financial support from the Latvian Council of Science under the grant agreement LZP-2020/2-0009. Calculations were performed at the HLRS, University of Stuttgart, within the project 12939 DEFTD. The Institute of Solid State Physics, University of Latvia (Latvia), as the Centre of Excellence has received funding from the European Union’s Horizon 2020 Frame-work Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase2 under grant agreement No. 739508, project CAMART2.Sr-doped lanthanum scandate La1−xSrxScO3−δ (LSS) is a promising perovskite-type material for electrochemical applications such as proton conductors. Oxygen vacancy is a common defect in ABO3-type perovskites. It controls ion transport as well as proton uptake. The energetic, structural, and electronic properties of oxygen vacancy in LSS are studied deploying the DFT method with meta-GGA functional. The vacancy formation energies in LSS were calculated for various Sr concentrations. Unlike other perovskites, in this material, the electrons are trapped at the oxygen vacancy site (the F-type centres, common in ionic oxides like MgO and Al2O3) rather than localised on the nearest to the vacancy B-cations. The process of oxygen vacancy formation is considered relative to Sr concentration x and oxygen nonstoichiometry factor δ. Three primary regimes are discussed: (I) localized at the vacancy electrons, x/δ 2. For x/δ ≥ 2 oxygen vacancy formation energy reaches the saturation level of ~3.5 eV, which is potentially beneficial for the proton uptake. © 2022 by the authors.Latvian Council of Science LZP-2020/2-0009; the Institute of Solid State Physics, University of Latvia (Latvia), as the Centre of Excellence has received funding from the European Union’s Horizon 2020 framework programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase2 under grant agreement No. 739508, project CAMART2

    Multiscale fluctuations in nuclear response

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    The nuclear collective response is investigated in the framework of a doorway picture in which the spreading width of the collective motion is described as a coupling to more and more complex configurations. It is shown that this coupling induces fluctuations of the observed strength. In the case of a hierarchy of overlapping decay channels, we observe Ericson fluctuations at different scales. Methods for extracting these scales and the related lifetimes are discussed. Finally, we show that the coupling of different states at one level of complexity to some common decay channels at the next level, may produce interference-like patterns in the nuclear response. This quantum effect leads to a new type of fluctuations with a typical width related to the level spacing.Comment: 34 Latex pages including 6 figures (submitted to Phys. Rev. C

    Resonance-assisted tunneling in near-integrable systems

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    Dynamical tunneling between symmetry related invariant tori is studied in the near-integrable regime. Using the kicked Harper model as an illustration, we show that the exponential decay of the wave functions in the classically forbidden region is modified due to coupling processes that are mediated by classical resonances. This mechanism leads to a substantial deviation of the splitting between quasi-degenerate eigenvalues from the purely exponential decrease with 1 / hbar obtained for the integrable system. A simple semiclassical framework, which takes into account the effect of the resonance substructure on the KAM tori, allows to quantitatively reproduce the behavior of the eigenvalue splittings.Comment: 4 pages, 2 figures, gzipped tar file, to appear in Phys. Rev. Lett, text slightly condensed compared to first versio

    Results of multidisciplinary survey in the Laptev Sea in August-September, 2015

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    Data on oceanographic conditions and species composition of plankton, benthic and demersal fish and invertebrates are presented, obtained in the complex survey over the external shelf of the Laptev Sea in August-September 2015. The zooplankton abundance was low, with only local increases up to 400 mg/m3. Species diversity of fish and nekton invertebrates in the bottom trawl catches was low, too: 26 fish species and 2 species of cephalopods. Mean biomass of fish was estimated as 4.3 t/km2 (in total 132. 103 t within the surveyed area of 30,500 km2). All fish species were distributed sparse. Arctic cod was the most abundant and occurred over the whole surveyed area, with large-sized fish dominating at the bottom and medium-sized (9-15 cm) fish - in the pelagic layer, other commercial species were greenland halibut and deepwater redfish caught on the continental slope. Bottom invertebrates in trawl catches were presented by 6 species of shrimp and 12 taxonomic groups of different rank, with predominance of starfish, brittle stars and sponges; gastropods were represented by 11 species, with Neptunea heros dominating by mass (42 %). Macrobenthos in samples of the bottom sampler was presented by 20 taxonomic groups, with predominance of polychaetes, bivalves and sipunculoids

    Search for the Xb and other hidden-beauty states in the π+π−ϒ(1S) channel at ATLAS

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    This Letter presents a search for a hidden-beauty counterpart of the X(3872) in the mass ranges of 10.05–10.31 GeV and 10.40–11.00 GeV, in the channel Xb→π+π−ϒ(1S)(→μ+μ−), using 16.2 fb−1 of pp   collision data collected by the ATLAS detector at the LHC. No evidence for new narrow states is found, and upper limits are set on the product of the Xb cross section and branching fraction, relative to those of the ϒ(2S), at the 95% confidence level using the CLS approach. These limits range from 0.8% to 4.0%, depending on mass. For masses above 10.1 GeV, the expected upper limits from this analysis are the most restrictive to date. Searches for production of the ϒ(13DJ), , and states also reveal no significant signals

    Investigation of Graphene Formation from Graphite Oxide and Silicon Carbide

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    Graphene is a novel two dimensional material that is revolutionizing many areas of science and it is no surprise that a significant amount of effort is dedicated to its investigation. One of the major areas of graphene research is the development of procedures for large scale production. Among many recently developed methodologies, graphene oxide reduction stands out as a straightforward and scalable procedure for producing final material with properties similar to those of graphene. Laser reduction of graphite oxide is one of the novel approaches for producing multilayer graphene, and this work describes a viable approach in detail. It is determined that a material which is comprised of a combination of laser reduced graphite oxide-coupled to an unreduced graphite oxide layers beneath it, produces a broadband photosensitive material. The efficiency of light conversion into electrical current is greatly dependent upon the oxygen content of the underlying graphite oxide. Developing novel ways for reducing graphite oxide is an ongoing effort. This work also presents a new method for achieving complete reduction of graphite oxide for producing predominantly sp2 hybridized material. This approach is based on the irradiation of graphite oxide with a high flux 3 keV Ar ion beam in vacuum. It is determined that the angle of irradiation greatly influences the final surface morphology of reduced graphite oxide. Also, multilayer epitaxial graphene growth on silicon carbide in ultra-high vacuum was investigated with quadrupole mass spectrometry (QMS). Subliming molecular and atomic species were monitored as a function of temperature and heating time. The grown films were characterized with X-ray photoelectron spectroscopy coupled with Ar ion depth profiling.Ph.D

    Oxygen sensors based on gallium oxide thin films with addition of chromium

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    This article reveals the gas-sensitive properties of polycrystalline gallium oxide thin films with chromium additives. Incorporation of the Cr2O3 phase into the β-phase gallium oxide film structure leads to the Ga2O3 grain size decrease. The oxygen-sensitivity of the gallium oxide films appears at 300 C. The oxygen increases reversibly the sensor resistance due to an increase in the height of the energy band bending at the Ga2O3 grain boundary with the chemisorption of atomic O. The chromium oxide formed in the Ga2O3 films stimulated dissociative adsorption of the oxygen due to its high catalytic activity via a spill-over mechanism. The temperature range of 500–700 C appears to be the most efficient for the oxygen detection in the concentration range from 9 to 100 vol%. The response time of the sensor was 20 s at 700 C in an initial nitrogen- containing atmosphere at О2 exposure to 21 vol% and the recovery time comprised 52 s. Meantime, the sensors did not practically react to a gas reducing and high humidity
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