Production of electrolytic copper from Zhezkazgan Processing Plant tailings leaching solutions using a hydro-impulse discharge

In this work, for the first time, studies of the mineralogical composition and chemical semi-quantitative spectral analysis (SQSA) of the Zhezkazgan processing plant tailings before and after leaching were carried out. It was found that copper is present in the tailings in the form of the chalcosine and bornite minerals. After leaching with the use of ammonium bifluoride and a hydro-pulse discharge, chalcosine and boronite are destroyed, and copper passes into a solution containing phosphoric acid. As a result of multiple placing of tailings into the solution, the copper content in it is brought to a concentration at which copper deposition on a stainless steel plate is possible. The identification of copper was implemented on a LAES-Matrix grain spectrometer. A visual comparative analysis of the changes in the structure of the treated ore waste was carried out using a TESCAN MIRA scanning electron microscope. Metallic copper was obtained from solution by electrochemical reactions in an experimental laboratory setup as a result. The technology was developed on an experimental laboratory setup for the extraction of metallic copper and brought the choice of the solution medium and electrochemical processes to the stage of obtaining the target metal with a purity of 99.99 %

Statistical analysis of ENDOR spectra

Electron–nuclear double resonance (ENDOR) measures the hyperfine interaction of magnetic nuclei with paramagnetic centers and is hence a powerful tool for spectroscopic investigations extending from biophysics to material science. Progress in microwave technology and the recent availability of commercial electron paramagnetic resonance (EPR) spectrometers up to an electron Larmor frequency of 263 GHz now open the opportunity for a more quantitative spectral analysis. Using representative spectra of a prototype amino acid radical in a biologically relevant enzyme, the Y122• in Escherichia coli ribonucleotide reductase, we developed a statistical model for ENDOR data and conducted statistical inference on the spectra including uncertainty estimation and hypothesis testing. Our approach in conjunction with 1H/2H isotopic labeling of Y122• in the protein unambiguously established new unexpected spectral contributions. Density functional theory (DFT) calculations and ENDOR spectral simulations indicated that these features result from the beta-methylene hyperfine coupling and are caused by a distribution of molecular conformations, likely important for the biological function of this essential radical. The results demonstrate that model-based statistical analysis in combination with state-of-the-art spectroscopy accesses information hitherto beyond standard approaches.

Features of Heavy Metal Contamination of Agricultural Soils in the Kursk Region of Russia and Economic Assessment of Restoration

Kursk region of Russia has unique fertile soils. Heavy metals are among the factors that pollute the soil. The article is devoted to the study of the spatial distribution of heavy metals in soils. The relevance of the study is that the value of the soil is determined by its value for obtaining environmentally friendly agricultural products. Data on the content of heavy metals in the soil can prevent intensive cultivation of crops. The task of the work is to identify heavy metals that predominate in the soils of various landscapes of the Kursk region. The assessment of soil contamination with chemical elements was carried out in the course of geo-ecological studies of black earth soils in the Kursk region of Russia. The selected soil samples were examined by semi-quantitative spectral analysis. The results obtained were subjected to statistical processing. It was found that cobalt is the main pollutant in the vast majority of sampling points. In other zones, molybdenum, lead, zinc, and chromium predominate in approximately equal amounts. Soils in the surveyed area belong to the permissible category of contamination with chemical elements. Soil remediation should be applied in local areas.

Heavy metals in intermediate He-rich hot subdwarfs: the chemical composition of HZ 44 and HD 127493

Context. Hot subluminous stars can be spectroscopically classified as subdwarf B (sdB) and O (sdO) stars. While the latter are predominantly hydrogen deficient, the former are mostly helium deficient. The atmospheres of most sdOs are almost devoid of hydrogen, whereas a small group of hot subdwarf stars of mixed H/He composition exists, showing extreme metal abundance anomalies. Whether such intermediate helium-rich (iHe) subdwarf stars provide an evolutionary link between the dominant classes is an open question. Aims. The presence of strong Ge, Sn, and Pb lines in the UV spectrum of HZ 44 suggests a strong enrichment of heavy elements in this iHe-sdO star and calls for a detailed quantitative spectral analysis focusing on trans-iron elements. Methods. Non-local thermodynamical equilibrium model atmospheres and synthetic spectra calculated with TLUSTY/SYNSPEC were combined with high-quality optical, ultraviolet (UV), and far-UV (FUV) spectra of HZ 44 and its hotter sibling HD 127493 to determine their atmospheric parameters and metal abundance patterns. Results. By collecting atomic data from the literature we succeeded in determining the abundances of 29 metals in HZ 44, including the trans-iron elements Ga, Ge, As, Se, Zr, Sn, and Pb and providing upper limits for ten other metals. This makes it the best-described hot subdwarf in terms of chemical composition. For HD 127493 the abundance of 15 metals, including Ga, Ge, and Pb and upper limits for another 16 metals were derived. Heavy elements turn out to be overabundant by one to four orders of magnitude with respect to the Sun. Zr and Pb are among the most enriched elements. Conclusions. The C, N, and O abundance for both stars can be explained by the nucleosynthesis of hydrogen burning in the CNO cycle along with the stars’ helium enrichment. On the other hand, the heavy-element anomalies are unlikely to be caused by nucleosynthesis. Instead diffusion processes are evoked, with radiative levitation overcoming gravitational settlement of the heavy elements.

Methodology of selecting the algorithms for optimization of arc spectral analysis

The goal of the study is the choice of algorithms for optimization of arc atomic emission spectral analysis with MAÉS to elaborate the techniques of quantitative spectral analysis of different objects. The choice of the algorithms is performed on an example of geologic objects with alumosilicate matrix. Determination of the elemental composition of such geological objects is important for obtaining markers, studying geochronological processes, and searching for mineral deposits.

A quantitative spectral analysis of 14 hypervelocity stars from the MMT survey

Context. Hypervelocity stars (HVSs) travel so fast that they may leave the Galaxy. The tidal disruption of a binary system by the supermassive black hole in the Galactic center is widely assumed to be their ejection mechanism. Aims. To test the hypothesis of an origin in the Galactic center using kinematic investigations, the current space velocities of the HVSs need to be determined. With the advent of Gaia’s second data release, accurate radial velocities from spectroscopy are complemented by proper motion measurements of unprecedented quality. Based on a new spectroscopic analysis method, we provide revised distances and stellar ages, both of which are crucial to unravel the nature of the HVSs. Methods. We reanalyzed low-resolution optical spectra of 14 HVSs from the MMT HVS survey using a new grid of synthetic spectra, which account for deviations from local thermodynamic equilibrium, to derive effective temperatures, surface gravities, radial velocities, and projected rotational velocities. Stellar masses, radii, and ages were then determined by comparison with stellar evolutionary models that account for rotation. Finally, these results were combined with photometric measurements to obtain spectroscopic distances. Results. The resulting atmospheric parameters are consistent with those of main sequence stars with masses in the range 2.5–5.0 M⊙. The majority of the stars rotate at fast speeds, providing further evidence for their main sequence nature. Stellar ages range from 90 to 400 Myr and distances (with typical 1σ-uncertainties of about 10–15%) from 30 to 100 kpc. Except for one object (B 711), which we reclassify as A-type star, all stars are of spectral type B. Conclusions. The spectroscopic distances and stellar ages derived here are key ingredients for upcoming kinematic studies of HVSs based on Gaia proper motions.

Spectroscopic and Photometric Analysis of the HW Vir Star PTF1 J011339.09+225739.1

HW Vir systems are rare eclipsing binary systems including a subdwarf B star (sdB) with a faint companion, mostly M-dwarfs. Up to now, 19 HW Vir systems have been published, three of them with substellar companions. We report the spectroscopic as well as photometric observation of the eclipsing sdB binary PTF1 J011339.09+225739.1 (PTF1 J0113) in a close (a=0.722 ± 0.023 R⊙), short period (P = 0.0933731(3)d) orbit. A quantitative spectral analysis of the sdB yields Te.=29280 ± 720 K, log(g)=5.77 ± 0.09 dex, and log(y)=−2.32 ± 0.12. The circular orbital velocity of the sdB of K1=74.2 ± 1.7 km s−1 is derived from the radial velocity curve. Except for the strong reflection effect, no other light contribution of the companion could be detected. The light curves - recorded with ULTRACAM - were analyzed using the Wilson-Devinney code. We find an inclination angle of i=79.88 ± 0.18∘. Because our first attempts to determine q failed, we calculated large grids of synthetic lightcurves for several mass ratios. Because of degeneracy, good solutions for different mass ratios were found - the one at q = 0.24 is consistent with the sdB’s canonical mass (MsdB = 0.47 M⊙). Accordingly, the mass of the companion is M2=0.112 ± 0.003 M⊙. The radii of the two components were also derived: RsdB=0.178 ± 0.006 R⊙ and R2 = 0.158 ± 0.009 R⊙. Thus, the results for the secondary are consistent with an M-dwarf as secondary