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An energy-saving technology for irisation of glass articles by using a high-temperature plasma torch was developed. The effect of the outflow of the plasma-forming gas on the intensity of heating of the glass was investigated. An installation for irisation of glassware was developed. The optimal process parameters of the irisation of glass articles were determined. [ABSTRACT FROM AUTHOR]

We consider the possibilities of applying the plasmon-enhanced fluorescence of monoclonal antibodies labelled with fluorescein isothiocyanate (FITC) to the prostate-specific antigen (PSA) for increasing the immunofluorescence analysis sensitivity. An immunochemical test system featuring two center binding using a pair of noncompeting monoclonal antibodies in combination with silver plasmon nanoparticles was used for the first time for determining the PSA concentration. The advantages over the standard PSA immunofluorescence assay are as follows. The intensity of the recorded fluorescent signal is enhanced by 2.3–3.2 times in the presence of silver nanoparticles in comparison with the signal of the test system on the intact surface of a polystyrene plate. The signal-to-noise ratio is increased by up to two times. In addition to the plasmon-enhanced fluorescence, the effect of an intermediate polyelectrolyte layer for enhancement of the adsorption capacity of the primary PSA antibodies is shown, which, in turn, affects the fluorescence signal intensity. Growth of the plasmon fluorescence enhancement factor with increasing concentration of the labelled antibodies indicates suppression of the self-quenching of the fluorescent labels by metal nanoparticles. [ABSTRACT FROM AUTHOR]

The emission spectra of thin nanocrystalline films of Cu(In1 –xGax)(SySe1 –y)2 (CIGSSe) direct-gap solid solutions in the structure of solar cells, recorded upon continuous-wave laser excitation (~0.5 W/cm2) and nanosecond pulsed laser excitation with a power density in the range of 0.1–53 kW/cm2 at temperatures ranging from 10 to 300 K, are analyzed. It is found that stimulated emission (SE) occurs in thin CIGSSe films at temperatures from 10 to 90 K in the spectral range hν = 1.062–1.081 eV, with a minimum threshold-pump level of ~1 kW/cm2. It is shown that the spontaneous emission band is blue-shifted with an increase in the excitation intensity. It is also established that, with an increase in temperature, the photoluminescence (PL) band (upon weak excitation) and the stimulated-emission band are blue-shifted, whereas the PL band is red-shifted upon strong excitation. The possible reasons and mechanisms for the influence of temperature and excitation intensity on the spectral positions of the spontaneous and stimulated emission bands for the solid-solution films are discussed. [ABSTRACT FROM AUTHOR]

Abstract: The effect of molecular-beam epitaxy (MBE) growth conditions on properties of AlN epitaxial layers was investigated resulting in determination of optimal substrate temperature and ammonia flow. Optimal substrate temperature for growth of GaN and AlGaN layers was determined analyzing thermal decomposition rate of GaN. Based on the information, high electron mobility transistor heterostructures were grown on sapphire substrates using both ammonia and combined plasma-assisted/ammonia MBE modes. The highest achieved 2DEG mobility was 1992 cm2/(V s) (at 2DEG density of 1.17 × 1013 cm-2) which is the current state-of-the-art level. [ABSTRACT FROM AUTHOR]

Photoluminescence of CdSe colloidal nanocrystals of different topologies in an external electric field has been studied. It has been found that quenching of photoluminescence, which takes place in quantum dots, is proportional to the square of the field, and in elongated nanocrystals quenching of photoluminescence is proportional to the square root. A physical model of the mechanism of quenching based on tunneling of free charges through potential barrier nanocrystal/matrix has been proposed. [ABSTRACT FROM AUTHOR]

The photoluminescence of barium thiogallates doped with Eu, Ce, and Eu + Ce ions is studied over a wide range of excitation levels (10-10 W/cm). Introduction of 3 at.% Eu and 3 at.% Ce instead of 5 at.% Eu into a BaGaS matrix doubles the luminescence quantum yield of the phosphor. Doped BaGaS exhibits a high linearity in its luminescence intensity as a function of excitation level (a constant efficiency) up to 2·10 W/cm for excitation pulse durations of 8 ns, which corresponds to cw pumping at a power density of about 5·10 W/cm in terms of the concentration of excited ions. It is shown that using BaGaS:Eu,Ce along with the 'yellow' phosphor of a Nichia NS6L083 LED may increase its color rendering index from 0.64 to 0.80 with no reduction in its luminous efficiency. [ABSTRACT FROM AUTHOR]

The ability to use laser ablation for preparation of art pigment samples in quantitative analysis of their elemental composition by atomic emission spectroscopy of inductively coupled plasma is shown. The proposed technique enables one to eliminate errors associated with both the influence of strong acids and the stoichiometric disruption in a sample. [ABSTRACT FROM AUTHOR]

The chirality and chiroptical response of materials have attracted significant attention for their potential to introduce the new science of light-matter interactions. We demonstrate that collective mode formation under modal coupling between localized surface plasmon resonances (LSPRs) with a chiral arrangement and Fabry–Pérot (FP) nanocavity modes can induce chiroptical responses. We fabricated a cluster of isotropic gold nanodisks with a chiral arrangement (gold nano-windmills, Au-NWs) on the FP nanocavities of TiO2 and Au film. The differential absorption of the Au-NWs coupled with the FP nanocavities under left- and right-handed circularly polarized light irradiations in the far field was significantly enhanced compared with the differential absorption without the FP nanocavities. Far- and near-field analyses by numerical simulation revealed that the Au-NWs coupled with the FP nanocavities formed a collective mode in the near field, and the collective mode represented the chiroptical response in the far field. The light field with the large helicity, can be used in chiral light-matter interactions. The concept of collective mode formation using isotropic metal nanodisks coupled with FP nanocavities provides a platform for controlling complex light fields. [ABSTRACT FROM AUTHOR]

The layered Vuruchuaivench Intrusion (VI) is located in the eastern part of the Fennoscandian Shield and is part of the Early Paleoproterozoic Monchegorsk Intrusive Complex (MIC). The platinum metal mineralization of this intrusion is localized within a stratiform reef-type platinum-bearing horizon that is about 2 km long and 1–3 m thick; in some boreholes, up to 15–20 m. The dissemination of Fe–Cu–Ni sulfides containing platinum-group minerals (PGMs), silver, and gold is confined to areas of gabbronorites and anorthosites with a massive and very-textured structure, with a wide development of fluid-bearing minerals in the intercumulus of cumulative phases. The uniform distribution of rock-forming, trace, and rare-earth elements in the rocks of the platinum-metal reef (platinum-group element reef) and its host rocks suggests the formation of gabbronorites during intrachamber differentiation without supplying additional portions of the melt. The composition and ratios between platinum group minerals and sulfides and silicates indicate a close genetic relationship between PGMs and magmatic sulfides. As the temperature decreases, primary PGMs and sulfides are altered under the influence of high-T magmatic fluids and hydrothermal solutions, with the formation of a wide range of PGMs. Ores are dominated by palladium arsenides, stibioarsenides, and bismuth tellurides. The separation of an immiscible arsenide melt, with the formation of numerous drop-shaped and globular intergrowths dominated by Pd–Ni-arsenides and Pd-stibioarsenides, plays a significant role in the formation of platinum-metal mineralization within the Vuruchuaivench intrusion. In some sulfide impregnations, platinum diarsenide (sperrylite) occurs instead of globules composed of palladium and nickel arsenides. The formation of specific platinum-metal associations appears to be due to the addition of As, Sb, and other incompatible elements to the magma through extensive assimilation of Archean crustal rocks. [ABSTRACT FROM AUTHOR]

The debate surrounding the roles of thermal and non-thermal pathways in plasmonic catalysis has captured the attention of researchers and sparked vibrant discussions within the scientific community. In this review, we embark on a thorough exploration of this intriguing discourse, starting from fundamental principles and culminating in a detailed understanding of the divergent viewpoints. We probe into the core of the debate by elucidating the behavior of excited charge carriers in illuminated plasmonic nanostructures, which serves as the foundation for the two opposing schools of thought. We present the key arguments and evidence put forth by proponents of both the non-thermal and thermal pathways, providing a perspective on their respective positions. Beyond the theoretical divide, we discussed the evolving methodologies used to unravel these mechanisms. We discuss the use of Arrhenius equations and their variations, shedding light on the ensuing debates about their applicability. Our review emphasizes the significance of localized surface plasmon resonance (LSPR), investigating its role in collective charge oscillations and the decay dynamics that influence catalytic processes. We also talked about the nuances of activation energy, exploring its relationship with the nonlinearity of temperature and light intensity dependence on reaction rates. Additionally, we address the intricacies of catalyst surface temperature measurements and their implications in understanding light-triggered reaction dynamics. The review further discusses wavelength-dependent reaction rates, kinetic isotope effects, and competitive electron transfer reactions, offering an all-inclusive view of the field. This review not only maps the current landscape of plasmonic photocatalysis but also facilitates future explorations and innovations to unlock the full potential of plasmon-mediated catalysis, where synergistic approaches could lead to different vistas in chemical transformations. The authors present a comprehensive review exploring the mechanistic understanding of plasmonic photocatalysis through examining the evidence for and interplay of thermal and non-thermal effects in this broad class of reactions. [ABSTRACT FROM AUTHOR]

The large Zun-Kholba deposit, relating to a numerous group of orogenic-type gold deposits, is in the Eastern Sayan (Russia)—a segment of the Altai-Sayan fold system of the Central Asian Orogenic Belt. The paper discusses the results of mineralogical, geochemical, geochronological, and Pb-isotopic studies of gold mineralization; the purpose was to verify the genetic model of the deposit. Mineralogical and geochemical data obtained for ore bodies located between hypsometric levels from 1290 to 2090 m indicate a complex distribution of mineral associations at the deposit. There is no vertical and horizontal zonation in the distribution of mineral associations, in the chemical composition of the main ore minerals, as well as in the content of impurity elements in them. In dating ore-forming processes at the Zun-Kholba deposit, a comprehensive approach based on the study of K–Ar and Rb–Sr isotope systems of metasomatites was applied. The combination of Rb–Sr and 40Ar–39Ar methods allowed us to determine that the age of gold mineralization is 411 ± 2 Ma, while the age of the superimposed event, which is associated with redistribution of ore, as well as disturbance of the Rb–Sr and K–Ar isotopic systems of metasomatites, is about 380 Ma. Pb–Pb isotopic study of ore mineralization at the deposit and host Precambrian rocks allowed to prove the leading contribution of the latter in ore lead supply to the mineral-forming system. The model of formation of the Zun-Kholba orogenic gold deposit assumes a genetic relationship between ore-forming processes and intraplate alkaline mafic magmatism due to the impact of the plume in the Early Devonian time on the lithosphere of the Tuva-Mongolian terrane. [ABSTRACT FROM AUTHOR]

Random lasing was achieved in CdS and Zn0.65Cd0.35Se micropowders at optical pump levels of 0.1–2 MW/cm2 with N2-laser radiation at wavelength 337 nm. The random generation thresholds were 820 kW/cm2 for CdS and 740 kW/cm2 for Zn0.65Cd0.35Se micropowders. Introduction of Ca(Al0.1Ga0.9)2S4:Eu2+ and Ca4Ga2S7:Eu2+ chalcogenides into the mixture of micropowders of CdS and Zn0.65Cd0.35Se solid solutions led in both cases to a drop in the random generation threshold to 520 and 550 kW/cm2, respectively, and to the appearance of laser-radiation line structures and their increased intensities. This may have been caused by an increase in the number of feedback loops because of the introduction of additional scatterers. [ABSTRACT FROM AUTHOR]

In metal–dielectric nanostructures with metal inhomogeneities of about 10–100 nm in size strong local concentration of electromagnetic radiation at the frequencies of the incident (primary) and emitted (secondary) radiation occurs simultaneously with a considerable increase of the rate of nonradiative transitions (fluorescence quenching). The general principles of the use of metal–dielectric nanostructures to enhance the fluorescence and the experimental use of these principles for organic molecules, including biomolecules with fluorescent labels, are examined. [ABSTRACT FROM AUTHOR]

A brief review of surface enhanced Raman scattering (SERS) with metal–dielectric nanostructures and results of its application for cultural heritage studies with paintings as the representative example are presented. Twenty microcrystalline inorganic pigments were successfully detected with 10–100-fold sensitivity enhancement using 1-μg samples. [ABSTRACT FROM AUTHOR]

This work reports on the plasmonic properties of a symmetry-breaking system consisting of rhodium dual broken nanorings, in the ultraviolet–visible regime. In the structure, two rhodium broken rings are located with a separation on the scale of nanometers. As the separation, the light polarization, and the relative orientation of the broken angles are, respectively, varied, the plasmonic scattering efficiency of the system is investigated, using the finite difference time domain method. Multiple plasmonic resonances are revealed, and the associated asymmetry-induced Fano-like lineshapes are fitted to a model that employs multiple Fano lineshape functions. The resonance wavelengths, the spectral widths, and the characteristic q values are determined from the best fit parameters, and the plasmonic characteristics of the system are quantitatively probed. The results in this work may be beneficial in designs of plasmonic devices that operate at ultraviolet–visible wavelengths. [ABSTRACT FROM AUTHOR]

Results of galvanostatic anodic oxiding of specially prepared high-purity aluminum in aqueous solutions of complex compounds K3[Co(C2O4)3] and K2[Zn(edta)] with different concentrations in the current-density ranges of, respectively, (1.5–1.10) × 102 and 1.5–30 mA cm–2 are presented. Kinetic features of anodic oxiding indicating the presence of an oscillating electrochemical process are established. The following morphological features atypical of anodic alumina are revealed: "flaky and loose" formations for K2[Zn(edta)] and "monolithic" formations for K3[Co(C2O4)3]. The elemental composition and IR spectroscopic and photoluminescence characteristics of the formed oxides are presented. [ABSTRACT FROM AUTHOR]

Improving the quantum yield of non-toxic InP/ZnS QDs is essential for its commercial application in illumination and displays. In this work, single size Au nanoparticles (Au NPs) coated with different shell thicknesses of Al2O3 as well as TiO2 fabricated by atomic layer deposition were prepared and applied to enhance the photoluminescence of InP/ZnS QDs with different emission wavelengths. These oxide films were used to control the distance between Au NPs and QDs to inhibit the fluorescence resonance energy transfer (FRET) and to demonstrate the competitive mechanism of fluorescence enhancement and fluorescence quenching induced by local surface plasmon resonance. It was found that the size dependence of Au NPs and the FRET effect can be effectively alleviated by covering different oxide shells. When the Au NPs coated with 10 nm Al2O3 and 6 nm TiO2, the photoluminescence of InP/ZnS green QDs and red QDs can be increased by 3.46 times and 5.65 times, respectively. These results indicate that the fluorescence intensity of quantum dots with different emission wavelengths can be easily improved by coating Au NPs with different types of shells or with different thicknesses, exhibiting the promising application prospect in backlight and biometric recognition of QDs. [ABSTRACT FROM AUTHOR]

In this paper, we exploit the sol–gel method to synthesize zinc oxide green nanoparticles (ZnO-GNPs) with different concentrations of zinc acetate dehydrate [Zn(Ac)2–2H2O] such as 1, 5, 7, and 9 % using Aloe-Vera extracts. The Rietveld refinement analysis of X-rays diffraction (XRD) patterns of ZnO-GNPs reveals the hexagonal unit cell structure with the space group P63mc. Scanning electron microscope (SEM) characterization exhibits that size of the particles increases with increasing concentration of Zn(Ac)2–2H2O. The PL spectra show an excitonic emission and oxygen defects at room temperature. The bandgap of ZnO-GNPs increases with increasing Zn (Ac)2–2H2O concentration. The Raman spectra show strong E2 (H) vibrational mode along with A1 (TO) and E1(LO) Raman modes. The ZnO-GNPs demonstrate a strong antibacterial activity against Gram-positive (Staphylococcus aureus), ranging from 32 to 42 nm, and Gram-negative bacteria (Escherichia coli) in the range of 30–34 nm. These results suggest a potential use of green-synthesized ZnO-GNPs, being more eco-friendly than those synthesized by the chemical route, as an antimicrobial agent against drug-resistant microbes. Highlights: Green synthesis of ZnO with different concentrations of zinc acetate dehydrate is carried out using Aloe-Vera extracts. Aloe-Vera plant is used as the natural extract and as an effective reducing agent. The Rietveld refinement analysis of X-rays diffraction (XRD) patterns of ZnO-GNPs reveals the hexagonal unit cell structure with the space group P63mc. The bandgap energy increases largely with increasing concentration of Zn (Ac)2 -2H2O in ZnO-GNPs. Antibacterial activity against Gram-positive (Staphylococcus aureus) is found to be ranging from 32 to 42 nm and Gram-negative bacteria (Escherichia coli) from 30 to 34 nm. [ABSTRACT FROM AUTHOR]

Field and drill core hyperspectral sensing technologies are cost-effective tools for identifying footprints of hydrothermal mineral systems, vectoring towards potential ore bodies and differentiating domains in ore deposits. Hyperspectral visible-near, shortwave and thermal infrared data were collected from drill core and chip samples from the Cu-Zn-Mo deposit of Antamina, Peru, to map the relative abundance and chemical composition of major gangue minerals, such as garnet and quartz. This study focuses on grandite-series garnets (i.e. grossular to andradite), which show distinct variations with regard to their relative abundance and chemical composition across the Antamina deposit. Reflectance spectra were calibrated with quantitative mineralogy derived from scanning electron microscopy and X-ray diffraction-derived mineralogy. This allowed the modal abundances of garnet and quartz to be modelled using a partial least squares approach, achieving regression coefficients of up to 0.887 and 0.891, respectively. The accuracy of the modelled modal mineral abundance depended on the method of external calibration, and the mineral assemblage associated with the mineral of interest. Comparing the hyperspectral data with major sulfide mineralogy, whole-rock geochemistry, electron probe microanalysis and Fourier-transform infrared microscopy allowed the identification of five ore clusters at Antamina, including high Cu ± Zn-Mo; Zn + Cu ± Mo and Zn ± Cu in the exoskarn and Mo ± Cu-Zn and high Mo ± Cu-Zn in the endoskarn. The garnet species comprise mainly grossular ± andradite in the endoskarn and andradite in the exoskarn. Different garnet compositions are associated with different sulfide mineral assemblages, making Antamina an ideal candidate for evaluating hyperspectral sensing for rapid and reliable mineral characterisation of skarn deposits. Vector minerals typical of skarn deposits (e.g. garnet, vesuvianite) were determined using this approach, indicating its potential for effectively characterising skarn deposits worldwide. [ABSTRACT FROM AUTHOR]

Diblock copolymers of styrene with 4-vinylpyridine and tert-butyl acrylate are synthesized by reversible addition-fragmentation chain transfer polymerization. The diblock copolymer of styrene with acrylic acid is synthesized by acid hydrolysis of the tert-butyl acrylate block. By varying polymerization conditions, the diblock copolymers of the number-average molecular mass in the range of (22.4–115.8) × 103 and polydispersity from 1.09 to 1.28 are synthesized and characterized. The possibility of binding the synthesized copolymers to CdSe/ZnS quantum dots via poly-4-vinylpyridine and poly(acrylic acid) blocks is demonstrated. The effect of the indicated polymer stabilizers on the photostability of quantum dots in sols is evaluated. [ABSTRACT FROM AUTHOR]

The article presents the results of studying the chemical composition of ore-bearing rocks, as well as the mineralogy of base metal sulfides and platinum group elements (PGE), of the Nyud-II sulfide PGE–Cu–Ni deposit in the southwestern part of the Nyud massif of the Monchegorsk Pluton (Monchepluton). The ores of the deposit are represented by vein-disseminated and nest-schlieren types. They are characterized by significant predominance of Pd over Pt, fractionation of low-melting PGE (PPGE subgroup) with respect to high-melting ones (IPGE subgroup), and close correlations of Ni and Cu with S in the presence of increased As, Se, Te, and Bi contents. The S/Se ratios in ore (3470−3530) correspond to the mantle values. Among the platinum group minerals (PGM), the most widespread are Pt and Pd bismuth–tellurides and tellurides (merenskyite, michenerite, and moncheite), subordinate amounts of Pt–Fe alloys and sperrylite, and native osmium and Ir, Rh, and Pt sulfoarsenides (irarsite, hollingworthite, and platarsite). The formation of ore sulfide concentrations resulted from separation of an immiscible sulfide liquid upon cooling of a sulfur-saturated silicate magma with a mafic composition. Subsequent fractional crystallization of the sulfide liquid contributed to the uneven distribution of Ni, Cu, and PGE. PGE–sulfide ore formation took place in a fairly wide temperature range, starting at 1100−1000°C and ending at 600−400°C. At an early stage, IPGE minerals (native osmium and erlichmanite) separated. Upon cooling to a temperature of 1000−900°C, the sulfide liquid fractionated with the formation of monosulfide solid solution (mss), in which compatible IPGE were concentrated, and a residual sulfide liquid enriched in Ni, Cu, PtPGE, and chalcophile elements. With a further decrease in temperature (to 600°C), Pt–Fe alloys, sperrylite, and IPGE + Pt sulfoarsenides crystallized, with separation of the residual sulfide melt enriched in Cu, PPGE and chalcophile elements. At 600−400°C, ore formation ended with the complete crystallization of base metal sulfides and the formation of Pt and Pd bismuth–tellurides and tellurides. [ABSTRACT FROM AUTHOR]

Abstract—At present, plasmon effects in metal nanoparticles are used, among other purposes, for improvement in the efficiency of light-emitting diodes (LEDs). One new direction can be the application of plasmon properties of nanoparticles for improvement in the characteristics of wireless optical networks, in which data are transferred with the use of LEDs (Li–Fi networks). The study is concerned with issues related to the use of metal nanoparticles with dielectric shells to accelerate the modulation rate of LEDs and, as a consequence, to increase the data transfer rate in wireless optical networks due to an increase in the transition rates in a nanocrystal located near the nanoparticle surface. The dependences of the radiative and nonradiative transition rates in a nanocrystal on the emission wavelength are studied for different diameters of the metal core and different shell thicknesses. It is shown that, by specifying the optimal configuration of a nanoparticle with a shell, it is possible to create conditions such that the increase in the radiative transition rate at the emission wavelength of a nanocrystal will substantially exceed the increase in the nonradiative transition rate. This will allow acceleration of the modulation of LEDs without a loss in their energy efficiency as light sources. The results obtained here can be useful in studying the fluorescence of molecules and nanocrystals near nanoparticles and in improving the characteristics of Li–Fi optical data transfer networks. [ABSTRACT FROM AUTHOR]

A tunable plasmon-assisted electrochemiluminescence (ECL) strategy is reported using concave Au nanocubes (Au CBs) for rapidly accelerated fibrosarcoma B-type (BRAF) detection. Concave Au CBs exhibit a strong surface plasmon coupling (SPC) effect between its sharp apexes and edges. The high spectral overlap with graphite phase carbon nitride quantum dots (g-C3N4 QDs) is achieved by tuning surface plasmon absorption peak of the concave Au CBs. It maximizes the SPC effect and enhances the ECL signal of g-C3N4 QDs 3-fold. The SPC effect of Au CBs is twice as high as with Au NPs. We also employed a toehold-mediated strand displacement (TMSD) strategy for sensitive target recycling amplification. Under optimal conditions, this sensor can determine BRAF gene from 1 pM to 1 nM with a detection limit of 3.06 × 10−5 nM (S/N = 3) and RSD 3.67%. With the aid of the TMSD strategy and tunable plasmon-assisted ECL sensing mode, this sensor also exhibits good analytical performance in human serum with satisfactory recovery of 90.2~109%. The proposed strategy provides a promising method to effectively enhance spectral overlap and detect BRAF gene. [ABSTRACT FROM AUTHOR]

Some of the III–V semiconductor used in various devices suffer from the surface high density of states limiting their application. This study compares and evaluates five different ammonium sulfide passivation methods on GaAs surface with the aim to enhance the electrical characteristics of Au|n-GaAs Schottky junction. Wet chemical passivation of the n-GaAs surface was carried out by dipping the samples in saturated ammonium sulfide solutions at various temperatures and for various times. We also used acidic cleaning to improve the device performance. Our investigation shows a noticeable improvement in the electrical characteristics of the device reported here using acidic cleaning and ammonium sulfide passivation methods. A 23% increase in Schottky barrier height is found, which is much higher than that reported in the literature. Further, we measured a reduction of around three orders of magnitudes in saturation current as well as improvement in ideality factor to 1.23 for the best conditions of surface acidic cleaning and passivation. X-ray photoelectron spectroscopy study revealed a suppression of oxide layer by introduction of sulfide species in GaAs surface after the passivation. The lowest concentration of oxygen was found on the surface of the sample passivated under the optimum condition. [ABSTRACT FROM AUTHOR]

Monchetundraite, Pd2NiTe2 is a new mineral discovered in the the Monchetundra layered intrusion, Kola Peninsula, Russia. It forms euhedral grains (up to about 20 μm) intergrown with kotulskite and pentlandite. Monchetundraite is brittle and has a metallic lustre. In plane-polarized light, monchetundraite is white to creamy pinkish white, strongly pleochroic and strongly anisotropic on prismatic sections with rotations tints of pale blue, orange and olive green; it exhibits no internal reflections. Reflectance values (R1 nd R2) of monchetundraite in air are 44.3% and 45.8% at 470 nm; 48.7% and 50.7% at 546 nm; 51.4% and 53.7% at 589 nm, and 55.6% and 57.5% at 650 nm wavelength. Five electron probe micro-analyser (EPMA) measurements of monchetundraite give a mean composition of Pd 40.04 wt%, Cu 0.72 wt%, Fe 0.27 wt%, Ni 10.58 wt%, S 0.64 wt%, Te 48.20 wt%, total 100.07 wt%, which corresponds to the empirical formula (Pd1.96Cu0.06)∑2.02(Ni0.94Fe0.03)∑0.97 (Te1.97S0.04) ∑2.01 based on a total of 5 atoms. Means of eleven EPMA analyses on the synthetic analogue are Pd 40.85 wt%, Ni 10.78 wt%, Te 48.46 wt%, total 100.09 wt%, which corresponds to Pd2.03Ni0.97Te2.00. The mass density, calculated on the basis of the empirical formula, is 9.45 g/cm3. The mineral is orthorhombic, space group Ibam, with a 6.31111(13), b 11.2469(2) Å, c 5.16687(15) Å, V 366.75(1) Å3 and Z = 4. The crystal structure was solved and refined from the powder X-ray-diffraction data of synthetic Pd2NiTe2. Monchetundraite adopts the crystal structure of synthetic Pd2NiTe2, which was first determined by Pocha et al. (2007) and refined in this study. The strongest lines in the X-ray powder diffraction pattern of synthetic Pd2NiTe2 [d in Å (I) (hkl)] are: 2.8117 (100) (040), 2.6190 (33) (211), 2.5835 (32) (002), 2.3000 (41) (141), 2.1874 (39) (231), 2.1189 (22) (150), 2.0993 (22) (240), 1.9024 (52) (042), 1.8411 (26) (321), 1.3263 (32) (181). The mineral is named for the locality, the Monchetundra intrusion, Kola Peninsula, Russia. [ABSTRACT FROM AUTHOR]

Combining micro-X-ray absorption spectroscopy (μXAS) and micro-X-ray fluorescence spectroscopy (μXRF) is a promising approach for the investigation of complex multi-phase systems. In this work, we have employed this approach to investigate natural sphalerite, the most common form of Zinc Sulfide. Spatially resolved elemental distribution maps of common 3d metal atoms (Zn, Cu, Ni, Co, and Fe) are superimposed with chemical speciation and structural parameter maps in order to understand the sphaleriteore-formation process and metamorphosis. Chemical speciation and structural parameters have been obtained by analyzing the μXAS spectra collected in several representative points of the sample, after μXRF mapping. In the present case, this X-ray based approach has permitted to determine the spatial distribution of the Zn species in sphalerite. The presence of two main zincite and smithsonite inclusions has been established, with the latter located close to copper impurity center. Since copper is known to remarkably reduce the corrosion resistance of zinc, resulting in the formation of carbonate as the corrosion product, this implies a possible role of Cu in the growth of the carbonate inclusions. The results obtained highlight the efficiency of this method in univocally identifying the spatial distribution of phases in complex systems, thanks to the simultaneous access to complementary information. [ABSTRACT FROM AUTHOR]

Heterogeneous rhythmic–zonal aggregates of tennantite-IV partly or completely replacing early homogeneous Zn-tetrahedrite-I grains and euhedral (Fe–Zn)-tennantite-I crystal were found in ores of the Darasun gold deposit. The different stages of fahlore replacement were observed. This initiates at grain boundaries and is terminated by a complete transformation into pseudomorphic, newly formed (Zn–Fe)-tennantite-IV aggregates surrounded by Zn-tetrahedrite-IV. These aggregates closely associate with bournonite and galena, and their precipitation initiated the formation of pseudomorphs. As is evident from the results of EMPA, (Fe–Zn)-tetrahedrite enriched in As in relation to Zn-tetrahedrite-I was precipitated at the initial stage. Tennantite with wide variations in the Sb/(Sb + As) and Fe/(Fe + Zn) ratios predominates in zonal heterogenous aggregates. There is a negative correlation between Sb/(Sb + As) and Fe/(Fe + Zn) ratios in (Fe–Zn)-tetrahedrite–tennantite-IV. In all sites, there is a miscibility gap between As and Sb and a sharp decrease in Sb/(Sb + As) ratio and increase in Fe/(Fe + Zn) ratio at the contact between Zn-tetrahedrite-I and newly formed (Fe–Zn)-tetrahedrite–tennantite-IV. The sharp zigzag boundaries between Zn-tetrahedrite-I and tennantite-IV and pores in newly formed aggregates provide evidence for coupled dissolution–precipitation reactions. The dissolution was initiated by disequilibrium between Zn-tetrahedrite-I and undersaturated fluid due to the precipitation of galena and bournonite. The precipitation of tetrahedrite–tennantite-IV occurred under the conditions of oscillation in Sb/(Sb + As) and Fe/(Fe + Zn) ratios due to the gradient of concentrations in the fluid. The temperature of crystallization of zonal heterogenous tennantite-IV aggregates ((134–161) ± 20°С) was calculated by the sphalerite–fahlore geothermometer. Instability of early Zn-tetrahedrite-I results from hydrothermal fluid cooling, decrease in fluid salinity, and change in the tetrahedrite and tennantite solubility due to the evolution of the conditions of semimetal migration. [ABSTRACT FROM AUTHOR]

In the Pataz-Parcoy district, current mining activity is focused on the mesothermal quartz-carbonate-sulfide veins hosted by the Pataz batholith. Total gold production yielded approximately 8 Moz with grades in the mined ore shoots varying between 7 and 15 g/t Au, and locally reaching up to 120 g/t Au. High-grade ore shoots are extraordinarily enriched in sulfides, representing 10 to 20 modal vol% of the vein. Ore mineralogy is characterized by a complex paragenesis of pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, and gold. Gold occurs mostly as electrum in equilibrium with base metals sulfides filling fractures of pyrite and arsenopyrite. A novel combination of secondary ion mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, and electron probe microanalysis is used to track the compositional evolution of ore fluid(s) and to investigate the mineralization processes occurring in the Pataz-Parcoy district. Contrasting with the classical two-stage ore sequence previously proposed for the Pataz-Parcoy district, we suggest a revised paragenetic sequence, i.e., (1) deposition of pyrite core (PyI) with homogeneously distributed base metal sulfide inclusions, (2) progressive replacement of PyI by arsenian pyrite (PyII) and arsenopyrite associated with invisible gold deposition, and (3) deposition of sphalerite – galena ± chalcopyrite − electrum in fractured pyrite and arsenopyrite. We propose two models for the formation of base metal sulfide inclusions in PyI, i.e., (1) co-precipitation of base metal sulfide with PyI and later redistribution in cracks driven by partial As replacement of PyI to PyII and arsenopyrite and (2) preferential replacement of the PyI along crystallographic planes by percolation of the fluid responsible for base metal sulfide deposition in fractured pyrite and arsenopyrite. [ABSTRACT FROM AUTHOR]

The results of the U–Pb geochronological study of garnet from scarns of the Dashkesan deposit are reported. The first "direct" estimate of the age of the skarn formation and ore genesis for this deposit (147 ± 2 Ma) is obtained. The possibility of using the U–Pb garnet system to obtain estimates of the scarns age is shown. [ABSTRACT FROM AUTHOR]

Mineral assemblages, the peculiarities of intergrowths, chemical composition, and Sb and As distribution in coexisting fahlore and bournonite-seligmannite solid solutions of the Darasun gold deposit are studied. The almost complete solid solution between bournonite and seligmannite with continuous Sb–As isomorphism for Sb/(Sb + As) ratios from 0.21 to 1.00 is identified for the first time for the Darasun deposit using a microprobe. The composition of fahlore coexisting with bournonite widely varies: Sb/(Sb + As) ratio 0.03–0.96 and Fe/(Fe + Zn) ratio 0.36–0.87. The mutual compositional evolution from early Sb to late As coexisting solid solutions is identified. Based on the Sb and As distribution between coexisting fahlore and bournonite-seligmannite, the temperatures of their joint crystallization are estimated, as well as those of the productive stage, where they are associated with native gold and tellurides (90–335°C). [ABSTRACT FROM AUTHOR]

This study presents a new occurrence of hydrothermal argentopentlandite, associated with pyrrhotite, chalcopyrite, sphalerite, and galena in albite (± calcite, muscovite, pyrochlore-group minerals, high-Th phases) veins cutting metagabbro of the Sedova Zaimka intrusion, Western Siberia, Russia. The data obtained from petrography, mineral chemistry and fluid inclusion study of the vein-forming minerals do confirm the proposed hydrothermal origin of sulfides and associated gangue minerals from the internally-derived metamorphic fluids generated during potential post-peak contact metamorphic cooling. These ore-forming fluids were Na-dominant and enriched in Si, Al, Fe, Cu, with minor Ca, K, Ta, Nb, U, Th, Zn, Pb, Ni, Ag, Co, Bi, Te, Se, and Cd. They were characterized by moderate temperatures (270-325 °C) and moderate salinities (4.70-7.25 wt% NaCl equiv.) and belong to the NaCl-H2O fluid system with dominant CH4 gas-phase species. It is concluded that the components (metals and other elements) for the vein infill have been transferred from metagabbro by the metamorphic fluid, possibly in a dissolution-transport-precipitation process. [ABSTRACT FROM AUTHOR]

Djerfisherite in the monticellite rocks of the Krestovskaya Intrusion is found in primary melt inclusions, mono- and polysulfide globules, and in the djerfisherite–hydrogarnet segregations. Melt inclusions are represented by three types. Type I is observed in the cores of perovskite phenocrysts and monticellite grains and corresponds to one of the early crystallization stages of the parental larnite-normative alkali ultrabasic magma enriched in water and other volatiles. Daughter phases of the inclusions are clinopyroxene, serpentine, phlogopite, apatite, nepheline, hydrogarnet, magnetite, djerfisherite, pectolite, and calcite. In some type I inclusions, melt at 1230–1250°C was immiscibly split into two fractions: alkali silicate fraction and highly fluidized water-bearing low-silica fraction enriched in alkali, sulfur, and CO2. The types II and III inclusions in perovskite, monticellite, Ti garnet, and melilite were formed through the spatial separation of immiscible phases. This follows from the similarity of the modal composition of types II and III melt inclusions to the normative composition of immiscible fractions of type I inclusions. Type II inclusions contain mainly water-bearing silicate daughter phases (hydrogarnet, serpentine, phlogopite, and pectolite), as well as djerfisherite, calcite, and magnetite. Type III inclusions contain clinopyroxene, nepheline, apatite, magnetite, djerfisherite, calcite, and pectolite. The djerfisherite–hydrogarnet segregations are confined to the Ti-magnetite and perovskite phenocrysts and fractures radiating from them in monticellite. The mineral composition of the djerfisherite–hydrogarnet segregations together with their surrounding is similar to the composition of type II inclusions containing similar water-bearing silicates, djerfisherite, calcite, and magnetite. Such similarity gives grounds to relate the formation of the djerfisherite–hydrogarnet segregations, as type II inclusions, with the spatial separation and crystallization of highly fluidized low-silica melt enriched in water, alkalis, sulfur, and CO2. According to the homogenization experiment, the crystallization of highly fluidized melt at 990–1090°C was accompanied by silicate–sulfide immiscibility and the formation of globular, emulsion-like, and myrmekite structures in the djerfisherite–hydrogarnet segregations, as well as mono- and polysulfide globules with djerfisherite in the hydrogarnet–calcite–serpentine substrate. The formation of ferrobrucite–carbonate–hydrogarnet globules in the djerfisherite–hydrogarnet segregations was also related to melt immiscibility, which again confirms the magmatic origin of the latter. Sometimes, djerfisherite in the djerfisherite–hydrogarnet segregations becomes coarser and forms rims, bands, and veinlets, which is likely explained by the high mobility and low viscosity of sulfide melt. Scarce grains of heazlewoodite, godlevskite, and pentlandite hosted in the djerfisherite–hydrogarnet segregations frequently have the same shape as djerfisherite, which indirectly suggests their simultaneous crystallization from the same melt. The chemical composition of the djerfisherite from mono- and polysulfide globules, djerfisherite–hydrogarnet segregations, and type I inclusions, as most Yakutian kimberlites, is characterized by the high (12.1–16.7 wt %) Ni and low (0.1–0.9 wt %) Cu contents. The composition of the djerfisherite from types II and III inclusions differs in the lowered (3.3–1.6 wt %) Ni and elevated (40.9–53.2 wt %) Fe contents; type III inclusions have high Cu content: from 7.6 to 10.6 wt %. [ABSTRACT FROM AUTHOR]

Abstract: The effect of molecular-beam epitaxy (MBE) growth conditions on properties of AlN epitaxial layers was investigated resulting in determination of optimal substrate temperature and ammonia flow. Optimal substrate temperature for growth of GaN and AlGaN layers was determined analyzing thermal decomposition rate of GaN. Based on the information, high electron mobility transistor heterostructures were grown on sapphire substrates using both ammonia and combined plasma-assisted/ammonia MBE modes. The highest achieved 2DEG mobility was 1992 cm2/(V s) (at 2DEG density of 1.17 × 1013 cm-2) which is the current state-of-the-art level. [ABSTRACT FROM AUTHOR]

The partitioning of Fe and Zn between coexisting fahlore and sphalerite and fluid inclusions in sphalerite from the Darasun gold deposit have been studied. These data were used to estimate the formation temperature of the minerals by the sphalerite-fahlore geothermometer. The calculated crystallization temperature of 175-355°С is close to the homogenization temperature of fluid inclusions in sphalerite of 225-385°С.The estimated pressure for fluid inclusion trapping ranged from 340 to 1420 bar. The sulfur fugacity obtained from the FeS content in sphalerite associated with pyrite and the calculated temperature ranges from 10-5.5 to 10-11 bar. [ABSTRACT FROM AUTHOR]

The mineral assemblages, mode of occurrence, and chemical compositions of coexisting fahlore and sphalerite from the Darasun gold deposit have been described. Three generations of fahlore and three generations of sphalerite have been recognized. The FeS content in sphalerite coexisting with fahlore ranges from 0.8 to 9.4 mol %. The complete solid solution series Fe-tetrahedrite-Zn-tetrahedrite-Fe-tennantite-Zn-tennantite reflected in Sb/(Sb + As) and Fe/(Fe + Zn) ratios ranging from 0 to 0.97 and from 0.07 to 1.00, respectively, with a predominant negative relationship between these ratios has been identified for the first time at the deposit. Stepped, oscillatory, and combined stepped-oscillatory growth zonings within fahlore grains and heterogeneous aggregates of fahlore have been found. Fahlore is enriched in As with respect to Sb, and Zn-tetrahedrite is followed by Fe- and Zn-tennantite from early to late generation; Zn-tetrahedrite is followed by Fe-tennantite in zoned grains and overgrown rims; sphalerite crystallized at decreased temperature and sulfur fugacity. The evolution of the chemical composition of fahlores was caused by the evolving temperature, fluid salinity, and conditions of metal migration. [ABSTRACT FROM AUTHOR]

The influence of Ag plasmons and reduced graphene oxide (RGO) on ZnO nanorods (Z-NRs)-based photoanodes for photoelectrochemical splitting of water is the main focus of the present experimental study. Plasmonic layer of Ag is incorporated either as a base (Ag-Z-NRs) layer or as a top layer (Z-NRs-Ag) in an electrochemically deposited Z-NRs-based photoanodes. Z-NRs-Ag photoanodes exhibited better optical absorption as plasmonic layer stimulates charge transfer and restrain charge recombination. It had shown the photocurrent density of ~0.79 mA cm, at a bias of 1.4 V/RHE. A mediator layer of RGO when introduced in Z-NRs-Ag photoanodes synergistically with Ag plasmons enhances the photocurrent density to ~1.3 mA cm at a bias of 1.4 V/RHE. Structure and surface morphology of the synthesized photoanodes was studied using x-ray diffraction and field emission scanning electron microscopy. Elemental analysis and optical characterization was done using energy-dispersive x-ray analysis, UV-Visible absorption spectroscopy and Raman spectroscopy. The current-voltage characteristics, electrochemical impedance spectroscopy, Mott-Schottky analysis, photoconversion efficiency and incident photon to current conversion efficiency measurements have been used to substantiate our observations of synthesized photoanodes. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) observed in solid solutions of Ca(AlGa)S:Eu ( x = 0.1-0.3) is studied. It is shown that the increase in emission intensity by 18% is caused by changes in the x values and electronic 5 d → 4 f transitions in Eu ions. A change in the position of the emission spectrum or its partial shift toward shorter wavelengths is due to an increase in the aluminum concentration and a decrease in the crystal field energy. The energy of the zero phonon line E , redshift D, and the Stokes shift Δ S are determined. A decrease in the photoluminescence intensity maximum and an increase in the half-width of the spectrum are found in the temperature range of 10-300 K. The efficiency of emission at temperatures of 20 and 300 K is almost independent of the excitation power density of up to ~10 W/cm. The luminescence lifetime of Eu ions was 383, 357, 346, and 333 ns for x = 0, 0.1, 0.2, and 0.3, respectively. [ABSTRACT FROM AUTHOR]

This paper considers the use of bibliometric methods in library and information activities, as well as the role of libraries of the Republic of Belarus in increasing the publication activities of researchers and the promotion of scientific journals. [ABSTRACT FROM AUTHOR]

The Sarvian Fe skarn deposit is located in the Urumieh-Dokhtar magmatic arc, western Iran. The Sarvian quartz diorite intruded the surrounding Permian to Tertiary limy formation, culminated in thermal metamorphism as well as skarnification in which the Sarvian deposit formed. Microthermometry studies in the Sarvian skarn deposit reveal two distinct inclusion groups; group A with medium-high temperature and hypersaline and group B with low-medium temperature and low salinity. Group A inclusions which are entrapped during formation of prograde are thought to be derived from the magmatic source. Fluid boiling and subsequent developing of hydraulic fracturing led to inflow and/or mixing of early magmatic fluids (group A) with circulating groundwater culminated in formation of low salinity and low temperature fluid inclusions (group B) during the formation of retrograde assemblage. Fluid inclusion thermometry reveals the formation temperature and the salinity of 300-370 °C and 31-33 wt% NaCl for the prograde stage and 180-230 °C and 1-15 wt% NaCl for the retrograde stage of skarnification at Sarvian skarn rocks. Fe-mineralization as well as hydrothermal minerals occurred during retrograde metasomatism. The estimated depth and pressure of occurrence for prograde stage are 1000-1200 m and 100-150 bars, and for retrograde stage, these are about 200 m and 50 bars, respectively. Garnet and pyroxene, as the main constituent minerals of prograde stage, are the most informative minerals offering a suitable tool to constrain the skarnification conditions. Garnets in the Sarvian deposit are mainly grossular and andradite, showing both normal and inverse zoning as the result of variation in their chemical composition. Such types of zoning represent alternation of high acidity oxidation and low acidity oxidation conditions that were prevailed on skarnification in the Sarvian prograde assemblage. Also, chemical composition of the Sarvian pyroxenes shows an alternation of high oxygen fugacity and low oxygen fugacity conditions for their formation. This is also supported by fluctuation of the ratios of andradite to grossular and diopside to hedenbergite, denoting to an obvious shifting that was prevailed between oxidizing and redox conditions during formation of prograde assemblage in the Sarvian. Garnet-pyroxene thermometry determines the formation temperature of prograde assemblage between 370 and 550 °C at Sarvian skarn rocks which is verified also by fluid inclusion thermometry. Decomposition of limestone by reaction of high-temperature hydrothermal fluids with carbonate host rock resulted in injection of CO into the Sarvian system that caused oxidation, changing Fe to Fe culminated in the magnetite deposition. [ABSTRACT FROM AUTHOR]

The South Sopchinsky massif (SSM), Gabbro-10 (G-10) massif, and Moroshkovoe Lake (ML) target Monchegorsk area, Kola Peninsula, are located at the junction of the Monchepluton and Monchetundra layered intrusions. The intrusions were studied in detail as they are targets for platinum-group element (PGE) mineralization. The rocks in these targets comprise medium- to coarse-grained mesocratic to leucocratic gabbronorites, medium-grained mesocratic to melanocratic norites and pyroxenites, and various veins mainly comprising norite, plagioclase-amphibole-magnetite rocks, and quartz-magnetite rocks. The veins contain Ni-Cu-PGE mineralization associated with magnetite and chromite. In all targets, the contacts between gabbronorite and norite-pyroxenite are undulating, and the presence of magmatic (intrusive) breccias suggests that these rocks formed through mingling of two distinct magmatic pulses. In places, the gabbronorites clearly crosscut the modal layering of the norites and pyroxenites. Trace element data indicate that the gabbronorites have similar compositions to rocks of the upper part of the Monchetundra intrusion, whereas the norites and pyroxenites resemble rocks from the lower to intermediate stratigraphic levels of the Monchepluton, such as in the Nude-Poaz and Sopcha massifs. Sulfide mineralization in the studied targets principally consists of secondary bornite, millerite, and chalcopyrite. In contrast, the primary sulfide assemblage within the layered sequence of the adjacent Monchepluton is characterized by pentlandite, chalcopyrite, and pyrrhotite. Therefore, the mineralization in the studied targets is interpreted to be of a contact style. We argue that the studied area represents the contact zone between gabbronorites of the Monchetundra intrusion and norites and pyroxenites of the Monchepluton. In addition, the rocks were overprinted by postmagmatic veining and remobilization of contact style sulfide and PGE mineralization. [ABSTRACT FROM AUTHOR]

We present the results of a pilot investigation of multiple sulfur isotopes for the Ni-Cu-PGE sulfide mineralization of the ∼2.5 Ga Monchegorsk Igneous Complex (MIC). Base Metal Sulfide (BMS) compositions, Platinum Group Element (PGE) distributions, and Platinum Group Mineral (PGM) assemblages were also studied for different types of Ni-Cu-PGE mineralization. The uniformly low S content of the country rocks for the MIC as well as variable Sm-Nd isotope systematics and low-sulfide, PGE-rich mineralization of the MIC suggest that S saturation was reached via assimilation of silicates rather than assimilation of sulfur-rich lithologies. R-factor modeling suggests that the mixing ratio for silicate-to-sulfide melt was very high, well above 15,000 for the majority of our mineralized samples, as might be expected for the low-sulfide, PGE-rich mineralization of the MIC. Small, negative ΔS values (from −0.23 to −0.04 ‰) for sulfides in strongly metamorphosed MIC-host rocks indicate that their sulfur underwent mass-independent sulfur isotope fractionation (MIF) in the oxygen-poor Archean atmosphere before it was incorporated into the protoliths of the host paragneisses and homogenized during metamorphism. Ore minerals from the MIC have similar ΔS values (from −0.21 to −0.06 ‰) consistent with country rock assimilation contributing to sulfide saturation, but, also importantly, our dataset suggests that ΔS values decrease from the center to the margin of the MIC as well as from early to late magmatic phases, potentially indicating that both local assimilation of host rocks and S homogenization in the central part of the large intrusion took place. [ABSTRACT FROM AUTHOR]

Different genetic types of barite from colloform and clastic pyrite-rich ores from the weakly metamorphic Saf'yanovka volcanogenic massive sulfide (VMS) deposit (Central Urals) were studied in comparison with barite from the Semenov-1 and Semenov-3 seafloor hydrothermal fields (mid-Atlantic Ridge). Hydrothermal barite generally occurs as radial aggregates of tabular crystals in contrast to compact aggregates of tabular crystals with stylolite boundaries of anadiagenetic barite from the Saf'yanovka clastic ores. The Sr content in barite shows no relationship with the genetic types. The δS values of hydrothermal barite from both ancient and modern colloform sulfides match those of Silurian-Devonian and contemporary seawater, respectively. The lower δS (avg +19.6 ‰) of hydrothermal barite from the Semenov-3 clastic sulfides indicates light sulfur contribution from oxidation of fluid HS. The higher δS (avg +28.1 ‰) of anadiagenetic barite from the Saf'yanovka clastic ores reflects partial thermochemical reduction of seawater sulfate. Hydrothermal barite from the Saf'yanovka and Semenov-1 colloform ores formed from low- to moderate- T (172-194 °С and 83-233 °C, respectively) relatively low salinity (1.6-4.5 and 0.6-3.8 wt% NaCl, respectively) fluids, which underwent phase separation. Hydrothermal barite from Semenov-3 clastic sulfides associated with chalcopyrite crystallized from higher- T (266-335 °С) higher-salinity (4.8-9.2 wt% NaCl) fluids. The high salinity may indicate a contribution from a magmatic fluid. Anadiagenetic barite from Saf'yanovka was formed from moderate- T (140-180 °С), low- to moderate-salinity (1.4-5.4 wt% NaCl) pore fluids. Combining our new data with those for other seafloor hydrothermal barite occurrences, the following systematics can be defined. Barite associated with pyrite-rich sulfides forms at relatively low to moderate temperatures (<230 °C), barite associated with polymetallic-rich sulfides forms at moderately high temperatures (210-280 °C), and barite in assemblage with chalcopyrite records the highest temperatures (265-335 °C). The main source of sulfur for hydrothermal barite is seawater with a small contribution of isotopically light sulfur from partial oxidation of HS. A contribution from isotopically heavy sulfur remaining after thermochemical or bacterial partial reduction of seawater sulfate appears to be common in diagenetic/anadiagenetic barite. [ABSTRACT FROM AUTHOR]

The rocks of the Elet'ozero intrusion are characterized by high relative abundances of incompatible elements, with (La/Lu) varying from 2.1 to 36.6, and a distinct positive Ba anomaly, which may record crystallization of Ba minerals during the formation of mafic rocks. The anomalous Ba enrichment is probably associated with a large-scale fluid-mediated mass transfer during subduction of a lithospheric slab within the Karelian craton which was synchronous with the generation of magmas parental to the Elet'ozero pluton. The presence of Al-rich spinel in gabbroic rocks as early-formed magmatic phases suggests crystallization at relatively high pressures (~0.5 GPa or ~15 km depth). The oxygen fugacity changed with time during the evolution of the magmatic system, approaching its maximum values (approximately 1.5 log units above the quartz-fayalite-magnetite buffer) during extensive crystallization of Fe-Тi oxides. High oxygen fugacities, Ti enrichment of mafic rocks, and lack of any positive correlation between Mg-numbers and Ni content in olivine can be useful indicators of potentially mineralized mafic intrusions. [ABSTRACT FROM AUTHOR]

Gold and silver contents in Noril'sk ore are controlled by the amount of sulphides and bulk Cu grade. Relative concentrations, re-calculated to 100 % sulphide, depend on type of ore: they are higher for disseminated ore than for massive ore and are the highest for low-sulphide platinum ore. Gold occurs mainly as high-fineness Au-Ag alloy in pyrrhotite-rich ore, whereas silver enters chalcopyrite mainly as solid solution. Increase in Cu grade correlates with an increase in the concentration of silver in chalcopyrite. Gold and silver form discrete minerals such as Au-Cu alloys, Au-Ag alloys, tellurides, sulphides, selenides, sulphobismuthides, Ag and Ag-Pd chlorides in Cu-rich ores; they also enter the structures of complex platinum-group minerals. The Au-Ag mineralisation is related to the post-magmatic hydrothermal stage under temperature conditions of 350-50 °C. Silver entered crystallizing chalcopyrite in solid solution in the late-magmatic stage, while all of the gold and the remainder of the silver and some platinum-group elements were transported predominantly as chloride and hydrosulphide complexes in hydrothermal fluids. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) in the visible spectral range of CaBaGaS solid solutions activated with ions of rare-earth elements Eu and Er has been studied in the temperature range of 10-300 K. The PL spectrum contains a strong luminescence band peaking at 530 nm, which is due to the 4 f5 d → 4 f transitions in Eu ions and weak lines in the range of 650-675 nm, which are due to the F → I transitions in Er ions. The position of the PL spectrum and the total PL intensity are characterized by high temperature stability in the range of 10-300 K; the total PL intensity decreases by only 13% with respect to the maximum value at 10 K. The PL decay time and the activation energy of nonradiative recombination channels are found to be τ = 291 ns and E = 41 meV, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the results of the detailed mineralogical study of the pocket-disseminated tinzinc (cassiterite-sulfide) and vein-metasomatic tin-silver-polymetallic ores localized in the vent of the Mount Krasnaya paleovolcano (Krasnogorsky polymetallic deposit). The tin-zinc ores of the early Late Maastrichtian stage of the ore formation are associated with pipelike bodies of explosion breccias, were formed at a temperature of around 300°C, and include three mineral assemblages: the (1) pyrite, (2) productive quartz-cassiterite-sphalerite, and (3) late sulfosalt-galena-chalcopyrite ones. The vein-metasomatic tin-silver-polymetallic ores of the late Paleocene stage are associated with rhyolite bodies, controlled by the NW-oriented faults, and cut mineralized breccia. These ores were formed during a full two-stage hydrothermal cycle within the temperature interval from 500 to 1000°C and include five consecutive ore mineral assemblages: (1) wolframite-arsenopyrite, (2) cassiterite-sphalerite-pyrite-chalcopyrite, (3) stannite-Ag-bearing sulfosalt, (4) freibergite-galena, and (5) native silver-stephanite-acanthite. The tin-silver-polymetallic ores are assumed to have formed simultaneously with the extended silver-bearing galena-sphalerite veins cutting the Primorskaya Group volcanic rocks around the paleovolcano. In the extended vein zones, the tinsilver-polymetallic ores correspond to the uppermost (closest to the paleosurface) part of the vertical zoning. [ABSTRACT FROM AUTHOR]

The platinum-bearing Paleoproterozoic Vurechuaivench Massif in the Monchegorsk Pluton is made up of amphibolized and saussuritized gabbronorites, anorthosites, and norites. The geochemical features of the massif rocks are considered at four detailed areas. It was confirmed that the Vurechuaivench and Nyud-Poaz massifs are geochemically similar. The rare-earth element (REE) distribution in the rocks of the Vurechuaivench Massif is peculiar in the low total REE content (9.4-27.6 ppm), negative REE slope, significant LREE enrichment [La/Yb] = 3.7-8.7), and distinctly expressed positive Eu anomaly ([Eu/Eu*] = 1.2-2.2). The REE distribution pattern remains unchangeable throughout the entire section, including the rocks of the Pt reef, with a gradual upsection REE increase. It is suggested that the PGE reef of the Vurechuaivench Massif, as the Platinova Reef (Skaergaard massif) and Sonju-Lake Intrusion (Duluth complex), was formed during fractional crystallization in a large magma chamber without new magma influx. It is conceivable that the Vurechuaivench Massif is the allochthonous fragment of a large loppolith-like body, the lower portions of which compose the Nyud-Poaz Massif, while the middle part was almost completely eroded. [ABSTRACT FROM AUTHOR]

The process of curing of furfural acetone monomer FA, which is used in production of wood-polymer composites, is considered. The paper suggests chemical reactions of autonomous structuring of two main components of the monomer FA-mono- and difurfurylidene acetone with formation of a spatial polymer, which leads to an increase in operational properties of wood-polymer materials. [ABSTRACT FROM AUTHOR]

Cathodoluminescence spectra of the semiconductors (Ba,Ca)Ga(S,Se):(Eu,Ce,Er,Yb) were studied and compared with their photoluminescence spectra. It was found that electron energy was converted most efficiently into light energy by Ba thio- and selenogallate co-doped with Eu and Ce and also by Ca thio- and selenogallate doped only with Eu. [ABSTRACT FROM AUTHOR]

Chemisorption properties of calcium hydrogen phosphate dihydrate CaHPO·2HO with respect to Cu(II) and Zn(II) ions in Me(NO) mono- and bicomponent solutions were considered. [ABSTRACT FROM AUTHOR]