This paper studies the composition and properties of shells of bivalve mollusks (Crenomytilus grayanus, Callista brevisiphonata, and Mizuhopecten yessoensis) from coastal discharges with a view to ...the possibility of their use in photocatalytic water treatment systems. The clam shells are considered in terms of application in the form of a powder material as a precursor for creating photocatalysts, and also as a carrier of photocatalytic coatings. It was shown that the main phase composing the shell material was calcium carbonate in two crystallographic modifications—calcite and aragonite. The presence of inorganic impurities in all studied clam shells did not exceed one mass percent. The main share was made up of elements included in the composition of calcium carbonate, which confirmed the high bio-indifference of the materials under study. Depending on the physiological and environmental features of the structure of clam shells, different contents of the organic component in their composition were observed. The granulometric characteristics of crushed clam shells (average diameter, specific surface area, and distribution modality) were studied. It was shown that the maximum values of bending strength of 5 MPa and compressive strength of 2 MPa are characterized by Mizuhopecten yessoensis shells with the lowest porosity of 2.91%. The features of sorption and photosorption processes of both whole and crushed shells in relation to four organic dyes at different temperatures and degrees of illumination were studied. Based on crushed shells of Mizuhopecten Yessoensis and titanium dioxide, functional materials (CaxTiyOz) were obtained, and their morphology and photocatalytic properties were studied. An example of the practical use of clam shells as a carrier of a photocatalytic coating is given.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•Regenerated cylindrical photocatalytic materials based on ZnO and TiO2.•The created materials most effectively oxidize cationic organic pollutant - methylene blue.•The photocatalytic performance of ...the samples was tested in a solar water treatment plant of flow-through type.
This article considers the possibility of obtaining regenerated photocatalytic materials of cylindrical shape for flow-through water purification systems. The method of cementation in a ceramic base matrix was compared to the method of laser fusion with a ceramic base of standard powder photocatalysts (ZnO, TiO2) according to the criteria of photocatalytic activity. The obtained materials were tested in a flow-through water purification unit (WPU) during the photo-oxidation of cationic - methylene blue (MB) and anionic - methyl orange (MO) model organic pollutants. The efficiency of water purification from MB at three cycles of regeneration of the obtained materials’ photocatalytic surface by layer-by-layer grinding was shown.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Thick epitaxial Ca2Si(100) films were first grown on Si(111) substrates by forming a sacrificial Mg2Si(111) template and converting it into the Ca2Si template. It was found that a temperature of ...250 °C is sufficient to transfer it into the Ca2Si template with sufficient uniformity. During Ca and Si co-deposition at 250 °C, epitaxial Ca2Si(100) domains with two orientations are formed in a thin (100 nm) film, and increasing the substrate temperature to 300 °C leads to a deterioration in the Ca2Si crystalline quality due to a partial violation of its continuity and grain growth of the CaSi phase from Si substrate. An increase in the film thickness to 400 nm at 250 °C led to the appearance, in addition to the Ca2Si(100) epitaxial phase, of the second Ca2Si(010) epitaxial phase with both contributing to the LEED pattern. From the transmission and reflection spectra of the grown samples, it was found that Ca2Si film has a first direct interband transition at E1d = 1.095 ± 0.15 eV, strong defect adsorption lower 1.0 eV and dispersionless refractive index no ≤ 3.8. Eight Raman peaks and 6 FIR peaks were first registered and identified, which are in good agreement with theoretical calculations. The absorption coefficients characteristic of FIR peaks was determined, which can be used further in the quick estimation of the thickness of Ca2Si films through an intensity of FIR absorption peaks.
•Thick Ca2Si epitaxial films on Si(111) were first grown through a Mg2Si(111)1x7 template.•The optimum temperature (250 °C) of the Mg2Si layer conversion to Ca2Si was determined.•The epitaxial Ca2Si film has a first direct interband transition at E1d = 1.095 ± 0.015 eV.•Identified in Ca2Si positions and amplitudes of 8 Raman peaks and 6 FIR peaks.•A method for estimating the Ca2Si films thickness through FIR absorption peaks was tested.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Calcium bismuthate nanoparticles with orthorhombic and rhombohedral crystal lattices were synthesized and characterized by various techniques. The syntheses caused the formation of oxygen and ...cationic vacancies in bismuth‐deficient samples. Heat treatment of samples with anionic vacancies led to thermal annealing of oxygen vacancies in ambient air; the annealing process was reversible. Oxygen vacancies in Bi‐deficient CaBi6O10 governed the optical absorption beyond the fundamental absorption edge at E(hν) < Ebg ≈ 2.5 eV. Bandgap energies of the bismuthates with orthorhombic and rhombohedral lattices were 2.51 eV prior to annealing and 2.47 eV after annealing at 350 °C. The trend in photoactivity toward the degradation of methylene blue dye under visible light showed that the photoactivity of the orthorhombic samples (1‐3) increased with a decrease in the Ca:Bi ratio (1.0:6.3 to 1.0:4.3); the sample with lowest ratio (1.0:4.3) displayed highest photoactivity. By contrast, the rhombohedral samples (4‐6) showed increased photoactivity with increase in the number of Bi atoms; sample with highest ratio (1.0:6.3) displayed highest photoactivity.
The rates of decomposition of methylene blue under visible light irradiation in the presence of the calcium bismuthates correlate with the total light absorption by all six bismuthate samples. The photoactivity of the orthorhombic samples increased with a decrease in the number of bismuth species (i. e., Ca:Bi ratio decreased from 1.0:6.1 to 1.0:4.3), while the photoactivity of the rhombohedral samples increased with increase in the number of bismuth species (i. e., Ca:Bi ratio increased from 1.0:4.3 to 1.0:6.1).
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The authors study obtaining a composite material NiAl - Mo2B5 while carrying out thermally coupled reactions of self-propagating high-temperature synthesis with a deoxidizing aluminothermal stage. ...The authors established ultimate and phase composition of the obtained composite. The microstructure is studied. It is shown that the composite consists of the intermetallic phase NiAl with Mo2B5 inclusions.
The Ildeus mafic–ultramafic complex represents plutonic roots of a Triassic magmatic arc tectonically emplaced into the thickened uppermost crust beneath the Mesozoic Stanovoy collided margin. The ...mafic–ultramafic complex cumulates host Ni-Co-Cu-Pt-Ag-Au sulfide-native metal-alloy mineralization produced through magmatic differentiation of subduction-related primary mafic melt. This melt was sourced in the metal-rich sub-arc mantle wedge hybridized by reduced high-temperature H-S-Cl fluids and slab/sediment-derived siliceous melts carrying significant amounts of Pt, W, Au, Ag, Cu and Zn. Plutonic rocks experienced a pervasive later-stage metasomatic upgrade of the primary sulfide–native metal–alloy assemblage in the presence of oxidized hydrothermal fluid enriched in sulfate and chlorine. The new metasomatic assemblage formed in a shallow epithermal environment in the collided crust includes native gold, Ag-Au, Cu-Ag and Cu-Ag-Au alloys, heazlewoodite, digenite, chalcocite, cassiterite, galena, sphalerite, acanthite, composite Cu-Zn-Pb-Fe sulfides, Sb-As-Se sulfosalts and Pb-Ag tellurides. A two-stage model for magmatic–hydrothermal transport of some siderophile (W, Pt, Au) and chalcophile (Cu, Zn, Ag) metals in subduction–collision environments is proposed.
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CEKLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
While gold partitioning into hydrothermal fluids responsible for the formation of porphyry and epithermal deposits is currently well understood, its behavior during the differentiation of metal-rich ...silicate melts is still subject of an intense scientific debate. Typically, gold is scavenged into sulfides during crustal fractionation of sulfur-rich mafic to intermediate magmas and development of native forms and alloys of this important precious metal in igneous rocks and associated ores are still poorly documented. We present new data on gold (Cu-Ag-Au, Ni-Cu-Zn-Ag-Au, Ti-Cu-Ag-Au, Ag-Au) alloys from iron oxide deposits in the Lesser Khingan Range (LKR) of the Russian Far East. Gold alloy particles are from 10 to 100 µm in size and irregular to spherical in shape. Gold spherules were formed through silicate-metal liquid immiscibility and then injected into fissures surrounding the ascending melt column, or emplaced through a volcanic eruption. Presence of globular (occasionally with meniscus-like textures) Cu-O micro-inclusions in Cu-Ag-Au spherules confirms their crystallization from a metal melt via extremely fast cooling. Irregularly shaped Cu-Ag-Au particles were formed through hydrothermal alteration of gold-bearing volcanic rocks and ores. Association of primarily liquid Cu-Ag-Au spherules with iron-oxide mineralization in the LKR indicates possible involvement of silicate-metallic immiscibility and explosive volcanism in the formation of the Andean-type iron oxide gold-copper (IOCG) and related copper-gold porphyry deposits in the deeper parts of sub-volcanic epithermal systems. Thus, formation of gold alloys in deep roots of arc volcanoes may serve as a precursor and an exploration guide for high-grade epithermal gold mineralization at shallow structural levels of hydrothermal-volcanic environments in subduction zones.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The Paleozoic volcano-sedimentary rocks within the structural basement of the horst-and-graben system of the Catalan Coastal Ranges (CCR) are composed of black shale, volcaniclastic sediments, lava ...flows, sills and lithocrystalloclastic tuffs. Paleozoic sediments are depleted in high-field strength elements (HFSE) such as Nb, Ta, Zr, Hf and Ti, suggesting their accumulation within the Andean-type active continental margin environment. Volcanic rocks within the Paleozoic CCR sequence belong to shoshonitic and high-K volcanic series and are enriched in Cs, Rb and Ba and depleted in HFSE, which is consistent with their derivation from metasomatized (possibly through deep recycling of pelagic sediments) subduction-related mantle source. The presence of sills (sill-sediment complex) suggests that Paleozoic basement of the CCR was formed within the rifted active continental margin or an arc-back-arc basin system akin to the modern Western Pacific subduction configuration. This complex volcanic terroir hosts world-class wines of the Priorat DOQ region. The presence of framboidal pyrite and magnetite, siderite, sphalerite xenotime, (La–Ce–Nd)-monazite, zircon and baddeleyite, as well as cuprite, tenorite and cupriferous and native silver in volcanic-derived black shale (and consequently in the world-famous “llicorella” soil overlying it) may have had dramatic effects on wine quality and sensory characteristics. These mineral features, together with strong enrichment of Priorat shale in Au, Ag and, to a lesser extent, Pt could have pronounced effects on (1) rates and specific types of chemical reactions; (2) plant metabolism; (3) response to nutrient components and (4) determination of grape flavor. Volcanic wine terroirs, such as the Priorat DOQ region, are special geologic environments for wine growth, capable of producing unique wine aromatic and gustatory characteristics.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The work presents the results of experimental studies on the air purification efficiency after accelerated composting of a mixture of cattle manure and straw in a chamber-type biofermenter. The ...operation of an experimental plant that simulates this process is described. A process optimization criterion has been established, its values have been determined for each of the pollutants – ammonia and hydrogen sulfide. The maximum purification efficiency for ammonia is 92%, achieved at 47% moisture content of the filtering material and 58% compost weight parts at 30°C. For hydrogen sulfide, the maximum purification efficiency is 95%, achieved at 50% moisture content of the filtering material and 52% compost weight part at 28°C
Modern approaches to the creation of single-layer and multi-layer high-temperature coatings for the protection of heat-resistant carbon-containing composite materials from oxidation and erosion in ...the high-speed fluxes of oxygen-containing gases are analyzed. Particularly have been outlined the heat-resistant coatings, the main components of which are either super refractory transition metal borides (ZrB2, HfB2, TiB2) with the addition of carbides (SiC, ZrC, HfC, TiC, TaC), silicides (MoSi2, TiSi2, ZrSi2, TaSi2, WSi2) and nitrides (HfN, ZrN, TiN), or refractory oxides (HfO2, ZrO2), or more complex synthetic compositions based on oxide ceramics. The results of fire gas-dynamic tests of coatings of perspective compositions are presented. The potential architecture of ultra-high-temperature coatings with high efficiency of protective action is justified.
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