Stistaites of the South Urals

Research subject. Rare minerals of tin and antimony – stistaites from natural lead plates from the Severo-Svetlinskaya placer in the Chelyabinsk region and from microspherules of intermetallic compounds in the products of erosion of granites of the Kisegach complex in the Ilmeny Mountains.Materials and methods. Electron probe analysis and laser ablation with inductively coupled plasma were used to study the composition of the predominant minerals of intermetallic compounds in lead plates extracted during the washing of a gold-bearing placer, as well as from metal microspherules in the sandy fraction of eroded granites.Results. Two types of stistaite were identified: lead and arsenic-lead. Lead stistaites is sharply predominant, with its average composition (wt %) being Sb – 47.39, Sn – 38.75, Pb – 13.24, Cu – 0.06. The average composition of arsenic-lead stystaite (wt %) was found to be Sb – 43.89, Sn – 41.06, Pb – 11.02, As – 3.05, Cu – 0.47. Tin-lead microspherules from the destruction products of biotite granites of the Kisegach massif (Ilmeny Mountains) occasionally contain crystals and spotted precipitates of lead stistaite with the composition (wt %) of Sn 53.54, Sb 38.45, and Pb 7.42.Conclusions. It is assumed that, in both cases, the formation of alloys of intermetallic compounds of tin, lead and antimony with inclusions of native copper and iron was associated with granite magmatism.

SYNTHESIS AND PHYSICOCHEMICAL STUDY OF THE CERIUM AND CEFAZOLIN METAL COMPLEX

В данной работе коллективом авторов путём взаимодействия водных растворов хлорида трёхвалентного церия и натриевой соли цефазолина получено и выделено в твердом виде металлокомплексное соединение. Его элементный состав установлен с помощью метода рентгеноспектрального электронно-зондового анализа, описаны термические характеристики данного соединения, температура его разложения, состав и способ координации внутренней сферы данного металлокомплекса был уточнен методами термогравиметрии, и дифференциальной сканирующей калориметрии и методом ИК-спектроскопии. На основании полученных данных установлено, что внутренняя сфера металллокомплекса содержит в своем составе три молекулы цефазолина и три молекулы внутрисферной воды. Состав внутренней сферы отвечает брутто-формуле [CeCzl(HO) ]. На основании данных ИК- спектроскопии сделаны выводы о координации цефазолина к центральному иону через амидную и карбоксильную группы. In this work, a team of authors obtained and isolated in solid form a metal complex compound by the interaction of aqueous solutions of trivalent cerium chloride and sodium salt of cefazolin. Its elemental composition was determined using the X-ray spectral electron probe analysis. The thermal characteristics of this compound, the temperature of its decomposition, the composition and the method of coordination of the inner sphere of this metal complex were clarified by the methods of thermogravimetry, differential scanning calorimetry and IR spectroscopy. Based on the data obtained, the inner sphere of the metal complex contains three molecules of cefazolin and three molecules of inner-sphere water. The composition of the inner sphere corresponds to the formula [CeCzl(HO) ]. Taking into account IR spectroscopy data, the authors concluded that the most likely way of coordination of cefazolin to the central ion is through the amide and carboxyl groups.

Evaluation of the wear of the duckfoot sweep cultivator blades and the technology of their hardening

In recent years, research and developments related to the creation of new areas using nanotechnology take a special place in scientific achievements. They are developed and widely used in Physics, Chemistry, Biology, Electronics, Medicine, Food Production and to a much lesser extent in Engineering. This is due to the fact that there are different requirements to parts and products used in mechanical engineering, they have a complex shape, are made of different materials, production methods, heat treatment. While operating, their working layer undergoes degradation with a significant change in structure and their hardening using nanocoatings may turn out to be ineffective in both technical and economic aspects. In this case, only a specific approach, which is determined by comprehensive research with identification of the main factors of parts damageability in specific production and operation conditions, can be expedient. In addition, in some cases for hardening, repair and restoration of parts it is expedient to use surfacing methods with the introduction of modifying agents in a liquid bath during crystallization. These modifying agents are nano-and dispersed diamonds, which make it possible to adjust temperature parameters of crystallization, grain size, and stress level. This approach allows using high-alloyed, high-carbon electrodes even for thin-walled steel and cast iron products. In this case, the diamond inclusions additive plays the role of micro-refrigerators, which significantly change the crystallization temperature range. It is important to determine the optimal dose of the introduction of such a modifier and ensure uniform distribution the components in the coating. The presented work is devoted to the new technology development of hardening of cultivator blades metal with nano-and dispersed diamond additives, which are the part of the detonation charge from the disposal of ammunition. Nowadays, in agriculture, a large number of tillage implements are used for tillage, the working bodies of which are sweep blades. They are operated under conditions of abrasive particles impact, and this is accompanied by their intense wear with a corresponding change in the geometric dimensions of the main working surfaces. The worn sweep blades significantly reduce efficiency and quality of the carried-out work. The analysis of the effective choice of surfacing materials for hardening and improving their performance has been carried out and the nature of wear has been evaluated in order to identify areas of maximum damage and to determine the optimal method. It is known that T-590 and T-620 electrodes are used for the restoration surfacing of tillage implements. It was found the hardfacing of thin-walled parts is accompanied by a smaller heat sink and, in some cases, they are flooded with defect formation. To reduce it, a non-magnetic fraction of detonation charge from ammunition disposalin the form of an electrode modification was introduced, which ensured the uniform distribution the components in the coating. The method of the X-ray electron-probe analysis has been used to evaluate features of structure formation and component distribution along the perimeter of the coating. It was found out that this method of hardening reduces heat input and increases the microhardness and wear resistance of the surfaced coating, reduces the transition zone and thermal impact. The recommended method of metal hardening of new cultivator blades is to apply stripes on the point tip and wings of blades. On the basis of the nature of wear, the expediency of applying stripes on the point tip of the cultivator blade from the front side, and on wings from the rear side, is justified. The optimal geometrical dimensions of hardening stripes and their location on the blade are presented, which allows minimizing the local stresses and increasing wear resistance.

TEM and DFT study of basal-plane inversion boundaries in SnO2-doped ZnO

In our recent study (Ribic et al. 2020) we reported the structure of inversion boundaries (IBs) in Sb2O3-doped ZnO. Here, we focus on IBs that form in SnO2-doped ZnO. Using atomic resolution scanning transmission electron microscopy (STEM) methods we confirm that in SnO2-doped ZnO the IBs form in head-to-head configuration, where ZnO4 tetrahedra in both ZnO domains point towards the IB plane composed of a close-packed layer of octahedrally coordinated Sn and Zn atoms. The in-plane composition is driven by the local charge balance, following Pauling's principle of electroneutrality for ionic crystals, according to which the average oxidation state of cations is 3+. To satisfy this condition, the cation ratio in the IB-layer is Sn4+: Zn2+=1:1. This was confirmed by concentric electron probe analysis employing energy dispersive spectroscopy (EDS) showing that Sn atoms occupy 0.504 ? 0.039 of the IB layer, while the rest of the octahedral sites are occupied by Zn. IBs in SnO2-doped ZnO occur in the lowest energy, IB3 translation state with the cation sublattice expansion of ?IB(Zn-Zn) of +91 pm with corresponding O-sublattice contraction ?IB(O-O) of -46 pm. Based on quantitative HRTEM and HAADF-STEM analysis of in-plane ordering of Sn and Zn atoms, we identified two types of short-range distributions, (i) zigzag and (ii) stripe. Our density functional theory (DFT) calculations showed that the energy difference between the two arrangements is small (~6 meV) giving rise to their alternation within the octahedral IB layer. As a result, cation ordering intermittently changes its type and the direction to maximize intrinsic entropy of the IB layer driven by the in-plane electroneutrality and 6-fold symmetry restrictions. A long-range in-plane disorder, as shown by our work would enhance quantum well effect to phonon scattering, while Zn2+ located in the IB octahedral sites, would modify the bandgap, and enhance the in-plane conductivity and concentration of carriers. Keywords

Studies on heap leaching of gold with the addition of sodium acetate as an intensifying reagent

One of the cheapest methods of extracting gold is heap leaching. However, the recovery of gold by this method is relatively low, compared with cyanidation of the crushed material, so the search for the ways to intensify leaching and increase gold recovery is an urgent task. Investigations on heap leaching of gold from the gold-bearing ore of the Sari Gunay deposit were conducted using a promising reagent sodium acetate to intensify the heap leaching process. The results of assay-gravimetric, chemical, mineralogical and granulometric analyses of oxidized ore are presented. The average gold content in the ore was 2.90 g/t. According to the electron probe analysis, gold in the ore is present in the form of fine (micron) inclusions in minerals and ore rocks. Comparative studies on heap leaching of gold from the crushed ore with a grain size of –20 + 0 mm with the addition of sodium acetate and without that were carried out. The degree of gold recovery with sodium acetate at a flow rate of 0.5 kg/t was 58.74%, that without sodium acetate was 54.69%, i.e. the addition of the reagent provides an increase in recovery of more than 4%. Leaching with the addition of the reagent also reduces sodium cyanide consumption from 0.65 to 0.59 kg/t. The research results have shown that sodium acetate can be used to intensify the process of heap leaching of gold when the ore size is –20+0 mm.

Study of the process of cyanide leaching of gold using sodium acetate at different ore sizes

Intensification of metal extraction by leaching is a complex of organizational and technical measures aimed at achieving the fastest and complete extraction of metal from ore. Measures to intensify leaching are aimed at completely or partially neutralizing the causes that cause a decrease in the leaching rate. Tests were performed on cyanide leaching of gold from gold-containing ore with the addition of sodium acetate to intensify the leaching process. The results of assay-gravimetric, chemical, mineralogical and granulometric analysis of oxidized ore are presented. According to electron-probe analysis, gold in the ore is present in the form of thin (micron) inclusions in minerals and ore rocks. A study was conducted on leaching of crushed ore with a size of 90% of the class -0.074 mm and crushed ore with a size of -12+0 mm. Leaching of crushed ore with a size of 90% of the class -0.074 mm showed that when adding sodium acetate, the gold recovery rate increases by 1.13 % compared to leaching without adding this reagent. When leaching crushed ore with a size of -12 + 0 mm with the addition of acetate, gold recovery increases by an average of 4 %, and the kinetics of gold dissolution improves. Research data prove that sodium acetate can be used to intensify gold at a ore size of -12+0 mm and in larger ore classes for leaching gold.

Chenmingite, FeCr2O4 in the CaFe2O4-type structure, a shock-induced, high-pressure mineral in the Tissint martian meteorite

Chenmingite (FeCr2O4; IMA 2017-036) is a high-pressure mineral, occurring as micrometer- to submicrometer-sized lamellae within precursor chromite grains along with xieite and Fe,Cr-rich ulvöspinel next to shock-induced melt pockets, from the Tissint martian meteorite. The composition of type chenmingite by electron probe analysis shows an empirical formula of (Fe2+0.75Mg0.23Mn0.02) (Cr1.60Al0.29Fe3+0.06Fe2+0.04Ti0.02)Σ2.01O4. The general and end-member formulas are (Fe,Mg)(Cr,Al)2O4 and FeCr2O4. Synchrotron X-ray diffraction reveals that chenmingite has an orthorhombic Pnma CaFe2O4-type (CF) structure with unit-cell dimensions: a = 9.715(6) Å, b = 2.87(1) Å, c = 9.49(7) Å, V = 264.6(4) Å3, and Z = 4. Both chenmingite and xieite formed by solid-state transformation of precursor chromite under high pressure and high temperature during the Tissint impact event on Mars. The xieite regions are always in contact with melt pockets, whereas chenmingite lamellae only occur within chromite, a few micrometers away from the melt pockets. This arrangement suggests that chenmingite formed under similar pressures as xieite but at lower temperatures, in agreement with experimental studies.

Histochemical changes in skin burn wound regeneration after application of titanium nickelide alloy supernatant

Objective : to determine the content and distribution in the tissues of the skin of various glycosaminoglycans (GAGs) against the background of the local action of the supernatant of the titanium nickelide alloy, to reveal the positive effect of the substrate on the dynamics of the formation of the regenerative process. Material and methods. The study was carried out on 25 Syrian hamsters (Mesocricetus auratus, Waterhouse, 1839). In stages 1, 3, 7, 14, 21 and 28 days, an overdose of sevoran anesthesia followed by decapitation was used to take the skin flap. The material was processed and poured into paraffin according to the standard conventional procedure. Histological sections were stained with alcian blue with a pH of 1.0 and 2.5, according to Tenzer-Unna. To determine the content of nickel and titanium cations, the electron-probe analysis method applied to the skin grafts taken in all experimental groups was used. Results. the increased accumulation of GAG in the dermis of the control group of animals occurred for a period of 21 days, while in the experiment their maximum was reached already by 14 days. Variations in GAG content in the epidermis and derivatives are associated with a change in the proliferative and biosynthetic activity of the cells of these structures at different periods of the experiment. Given the negative charge of sulfated aminoglycans and the hydrophilic base of the supernatant, penetration of the base metal cations of the supernatant into damaged tissues was detected by scanning microscopy. Conclusions. The reparative processes with the supernatant of the titanium nickelide alloy are more intensive, due to the limitation of the destructive process within the epidermis and the dermis, the reduction of purulent necrotic complications in the healing process, the interaction of nickel and titanium anions and cations in mineral and water metabolism. This ensures an earlier occurrence and uniform maturation of the young connective tissue, epithelization with normalization of cell proliferation and differentiation processes.

Hydrothermal Metasomatism and Gold Mineralization of Porphyritic Granite in the Dongping Deposit, North Hebei, China: Evidence from Zircon Dating

A porphyritic granite intrusion was recently discovered in the Zhuanzhilian section of the Dongping gold deposit. There is as many as one tonnage of Au in the fractured shear zone within the porphyritic granite intrusion, but no relevant reports concerning the origin and age of the intrusion has been published as yet. In this paper, zircon U-Pb dating is used to study the geochronology of porphyritic granite, in order to find out the evidence of age and the relationship with gold mineralization. There are two groups of zircon 207Pb/235U-206Pb/238U concordant ages of porphyritic granites: The concordant age of 373.0 ± 3.5 Ma, with the weighted mean age of 373.0 ± 6.4 Ma; and the concordant age of 142.02 ± 1.2 Ma with the weighted mean age of 142.06 ± 0.84 Ma. We believe that the first group might represent the age of residual zircon of alkaline complex, while the second group might be related with main gold mineralization. The obtained results of the petrography and electron probe analysis indicate that the porphyritic quartz and porphyritic granite, as well as gold mineralization, might be products of a late replacement of tectonic-hydrothermal fluid, which was rich in Si, Na and K originally and later yielded gold-forming fluids.