The study presents the results of research on the chemical composition of water in quarry lakes of the lithium-beryllium Zavitinskоyе and fluorite-beryllium Ermakovskoye deposits located in the ...Eastern and Western Transbaikalia, respectively. Currently, the mines are abandoned, and the quarry lakes are actively used by the population of nearby villages for domestic and recreational purposes. It was found that the water in the quarries of these deposits is brackish and fresh, belonging to the sulfate-magnesium-calcium and hydrocarbonate-sulfate-magnesium-calcium types with a neutral and slightly alkaline reaction and high contents of sulfates and certain metals (Li, Be, Zn, Al, Mn, Fe, Sr, etc.). Significant variations in the concentrations of trace elements in the identified types of water indicate the significant role of the hydrogeochemical environment (pH, Eh, mineralization, etc.) in their dispersion or accumulation. The beryllium content in the water of Zavitinskоyе deposit quarries ranges from 0.35 to 10.1 μg/l, while in the Ermakovskoye quarry it ranges from 0.024 to 0.026 μg/l. The content of some regulated components in the water exceeds the maximum permissible concentrations established for fishery ponds and sanitary-hygienic norms by several orders of magnitude.
The chemical composition of the waters of quarry lakes formed as a result of the development of the Zavitinskoye lithium-beryllium deposit located in Eastern Transbaikalia (Russia) has been studied. ...The studied waters of the ore pits are fresh with a neutral and slightly alkaline reaction, mainly of the magnesium-calcium sulfate type. It was found that the quarry waters contain high concentrations of lithium (Li) and strontium (Sr), in isolated cases of arsenic (As). Low concentrations of other metals in man-made waters are due to the neutralizing effect of carbonates of host rocks and ores, but this does not make them environmentally safe. The content of trace elements in the waters of quarries relative to the background contents, as well as the standards of maximum permissible concentrations (MPC) of chemicals for the waters of water bodies of fishery importance and sanitary and hygienic indicators were determined. A distinctive feature of the studied quarry lakes, as well as other man-made reservoirs, is the low species diversity of zooplankton and macrophytes, which is mainly due to the small catchment area, the steepness of the shores, the absence of shallow waters and other factors.
The distributions of trace elements in pyrite were studied in samples of high-grade gold ores from the Talatui, Teremkyn, and Darasun deposits. The paper presents LA-ICP-MS data on concentrations of ...trace elements in pyrite in gold ores from mineral deposits of the Darasun goldfield, which were produced by a single fluid–magmatic system at various temperatures. The high-temperature pyrite was found to be enriched in Co, Se, and W, whereas the medium-temperature pyrite was enriched in Cu, Zn, Ag, Te, As, and In. The behaviors of some elements (Ni, Au, Bi, Sb, and Pb) seem to be independent of temperature. The identified trends and relations in the behaviors of elements can be used in studying the Au-Bi mineralization of the intrusion-related type.
Pyrrhotite (or Cu-poor) massive ores of the Skalisty mine located in Siberia, Russia, are unique in terms of their geochemical features. These ores are Ni-rich with Ni/Cu ratios in the range 1.3–1.9 ...and contain up to 12.25 ppm Ir + Rh + Ru in bulk composition, one of the highest IPGE contents for the Norilsk–Talnakh ore camp. The reasons behind such significant IPGE Contents cannot simply be explained by the influence of discrete platinum-group minerals on the final bulk composition of IPGE because only inclusions of Pd minerals such as menshikovite, majakite, and mertieite II in Pd-maucherite were observed. According to LA-ICP-MS data obtained, base metal sulfides such as pyrrhotite, pentlandite, and pyrite contain IPGE as the trace elements. The most significant IPGE concentrator being Py, which occurs only in the least fractionated ores, and contains Os up to 4.8 ppm, Ir about 6.9 ppm, Ru about 38.3 ppm, Rh about 36 ppm, and Pt about 62.6 ppm. High IPGE contents in the sulfide melt may be due to high degrees of partial melting of the mantle, interaction with several low-grade IPGE impulses of magma, and (or) fractionation of the sulfide melt in the magma chamber.
The Oktyabrsk PGE-Cu-Ni deposit is one of the largest resources in the Norilsk–Talnakh ore district, Russia, and it is viewed as an ore giant on a global scale. It contains three types of ores: ...massive, disseminated and veinlet-disseminated. The two former ore types were formed by a liquation process, whereas the latter was associated with fluid-induced selective metasomatic replacement of metamorphosed wall rocks. One of the major ore minerals in all ore types is chalcopyrite. In this study, we determined concentrations of trace elements in this mineral using laser ablation inductively coupled plasma mass spectrometry. It appeared that standard geochemical tools, such as plotting the data in the form of diagrams of normalized concentrations, binary and ternary plots, do not allow one to distinguish chalcopyrite from visually and genetically different ore types. In contrast, more advanced statistical methods such as cluster analysis show different groupings of elements for each ore type. Based on the element clustering, a classification tree was suggested, which allowed for the differentiation of massive, disseminated and veinlet-disseminated ore types of the Oktyabrsk deposit by Se, Te, Cd and Pb concentrations in chalcopyrite with a success rate of 86%. The general feature is that chalcopyrite of veinlet-disseminated ore is poorer in these elements compared to chalcopyrite of the two other ore types. Chalcopyrite of massive ore is poorer in Se and Te when compared to chalcopyrite of disseminated ore.
A significant part of the primary gold reserves in the world is contained in sulphide ores, many types of which are refractory in gold processing. The deposits of refractory sulphide ores will be the ...main potential source of gold production in the future. The refractory gold and silver in sulphide ores can be associated with micro- and nano-sized inclusions of Au and Ag minerals as well as isomorphous, adsorbed and other species of noble metals (NM) not thoroughly investigated. For gold and gold-bearing deposits of the Urals, distribution and forms of NM were studied in base metal sulphides by laser ablation-inductively coupled plasma mass spectrometry and by neutron activation analysis. Composition of arsenopyrite and As-pyrite, proper Au and Ag minerals were identified using electron probe microanalysis. The ratio of various forms of invisible gold—which includes nanoparticles and chemically bound gold—in sulphides is discussed. Observations were also performed on about 120 synthetic crystals of NM-doped sphalerite and greenockite. In VMS ores with increasing metamorphism, CAu and CAg in the major sulphides (sphalerite, chalcopyrite, pyrite) generally decrease. A portion of invisible gold also decreases —from ~65–85% to ~35–60% of the total Au. As a result of recrystallisation of ores, the invisible gold is enlarged and passes into the visible state as native gold, Au-Ag tellurides and sulphides. In the gold deposits of the Urals, the portion of invisible gold is usually <30% of the bulk Au.
Abstract According to a new paradigm of carcinogenesis, a tumor arises not from transformed cell, but only from tumor initiating cells called cancer stem cells (CSCs), which can originate from tissue ...stem cells. CSC are resistant to conventional therapy and after treatment form new tumors and give rise to metastases. Only natural killer (NK) cells are capable of lysing CSCs, but within different tumor types these cells experience a condition known as “split anergy”, whereby the NK cells lose the ability to kill CSCs and being to produce cytokines. As a result, uncontrolled tumor growth arises and tumor stroma accumulates anergic NK cells. We hypothesize that anergic tumor infiltrating NK (TINK) cells transmit their property to naïve NK cells by infecting” them with a state of “split anergy” in a similar manner as T conventional cells are transformed into T regulatory cells during the process of “infectious tolerance”. Anergic TINK cells egress from the tumor stroma via the lymphatic system, where they reach regional lymph nodes and transmit their properties to naïve NK cells, which in turn become anergic toward CSCs and lose immunosurveillance functions. The mechanisms proposed for this hypothesis and the methodological approaches for confirming the idea are presented in this issue.
Despite the considerable progress toward the eradication of meningococcal disease with the introduction of glycoconjugate vaccines, previously unremarkable serogroup X has emerged in recent years, ...recording several outbreaks throughout the African continent. Different serogroup X polysaccharide-based vaccines have been tested in preclinical trials, establishing the principles for further improvement. To elucidate the antigenic determinants of the MenX capsular polysaccharide, we generated a monoclonal antibody, and its bactericidal nature was confirmed using the rabbit serum bactericidal assay. The antibody was tested by the inhibition enzyme-linked immunosorbent assay and surface plasmon resonance against a set of oligosaccharide fragments of different lengths. The epitope was shown to be contained within five to six α-(1–4) phosphodiester mannosamine repeating units. The molecular interactions between the protective monoclonal antibody and the MenX capsular polysaccharide fragment were further detailed at the atomic level by saturation transfer difference nuclear magnetic resonance (NMR) spectroscopy. The NMR results were used for validation of the
in silico
docking analysis between the X-ray crystal structure of the antibody (Fab fragment) and the modeled hexamer oligosaccharide. The antibody recognizes the MenX fragment by binding all six repeating units of the oligosaccharide
via
hydrogen bonding, salt bridges, and hydrophobic interactions.
In vivo
studies demonstrated that conjugates containing five to six repeating units can produce high functional antibody levels. These results provide an insight into the molecular basis of MenX vaccine-induced protection and highlight the requirements for the epitope-based vaccine design.
Arsenian pyrite is an abundant mineral occurring in many geological settings at the Earth’s surface, including hydrothermal ore deposits which are the main source of Au. So-called “invisible” (or ...refractory) form of Au is present in pyrites in all types of these deposits, and its concentration is often directly correlated with As content. Here we report results of the investigation of the local atomic structure of Au in natural (Cu-Au-porphyry) and synthetic (450°C/ 1 kbar, 300°C/ Psat) As-free and As-bearing pyrites by means of X-ray absorption spectroscopy (XAS). In addition, the state of As was determined in pyrite samples from Carlin-type deposit. XANES/EXAFS measurements, compiled with previously published data, revealed the chemical state (valence state, local atomic environment) of Au and As in arsenian pyrites. Au is present in the solid solution state (Au
1+
in the Fe position, octahedrally coordinated by S atoms), as well as in Au
1+
2
S clusters (Au
1+
linearly coordinated by 2 S atoms). The admixture of As has no effect on the Au valence state and Au-S interatomic distance, except one synthetic sample containing a minor amount of FeAsS. Arsenic mostly incorporates into the anion site in pyrite lattice (S
1-
↔As
1-
). Our data demonstrate that pyrites of hydrothermal origin can host up to ~300 ppm of structurally bound “invisible” Au independently of As content.
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