Chloride Fluid Research Articles

The characteristics of V, Sc, Cr and Ni within the Cambrian terrigenous-carbonate deposits found in the Syuldyukar kimberlite field (Western Yakutia)

The investigation of the Syuldyukar kimberlite field, located within the Yakut diamond-bearing province, involved approximately 4,000 X-ray fluorescence (XFA) analyses and 150 inductively coupled plasma atomic emission spectroscopy (ICP AES) analyses on the host sedimentary rocks of the Upper Cambrian Holomolokha formation in proximity to the kimberlite bodies. The results indicated a disruption in the correlation ratios when compared to background concentrations, while subclark levels of vanadium (V), scandium (Sc), chromium (Cr), nickel (Ni), and other elements remained consistent. The elements were divided into three categories: typomorphic elements for kimberlites (Cr, Ni, Co), elements associated with carbonatites (barium (Ba), strontium (Sr), neodymium (Nd), zirconium (Zr)), and elements characteristic of basalts (V, Sc, zinc (Zn)). High positive correlation coefficients were established for the specified elements in the background concentrations. However, ICP analyses indicated significant decreases in the correlation between elements from different groups in the near-kimberlite space at the Syuldyukar site. X-ray diffraction (XRD) studies showed that in the compression areas, the correlation ratios of various elements were inconsistent when compared to the stretching areas. The analysis of the XRF and ICP data reveled that the average elemental concentrations in the background and near-tube space were nearly identical, except for some unusual hurricane values, with variations showing only slight changes. The positive correlation of several elements likely reflects background geological processes, including sedimentation in a marine basin and subsequent transformations such as hypergenesis, diagenesis, and catagenesis. The significant decrease in correlation coefficients, even with background concentrations remaining stable, is likely due to the redistribution of elements in the fluid resulting from phreatomagmatic explosions linked to the intrusion of kimberlites. Aqueous chloride fluids were observed to most actively redistribute elements in areas experiencing local tectonic compression. The identified changes in the correlation ratios of background elemental concentrations in sedimentary rocks containing kimberlite could act as a new indicator for locating hidden diamond-bearing kimberlites.

Gold in sulfide fluids revisited

Gold solubility was measured at temperatures of 350, 400, 450, and 490 °C and pressures of 500 and 1000 bar in an ’oxidized sulfide’ system, as a function of pHT (2 – 10) and sulfur concentration (m(Stotal) = 0.03 – 1.2 [mol·(kg H2O)-1]). In this system, sulfur primarily exists as H2S, H2SO3, H2SO4, their dissociation products, and radical species such as S2- and S3-. The complexes Au(HS)2-, Au2S22-, AuHS(aq), AuHS(H2S)3(aq), and AuOH(aq) were identified as the primary gold species in the experimental fluids, varying with pH and m(Stotal). The solubility constants for Au(HS)2-, a critical (hydro)sulfide complex, align excellently with literature for ’reduced sulfide’ fluids, where sulfur predominantly exists in the 2- oxidation state. New experimental data from the ’oxidized sulfide’ system were regressed along with reliable literature data from ’reduced sulfide’ systems to calculate standard thermodynamic properties and parameters of the Helgeson-Kirkham-Flowers (HKF) model. The solubility constants for charged complexes, Au(HS)2- and Au2S22-, increase sharply with temperature, whereas those for neutral species, AuHS(aq) and AuHS(H2S)3(aq), show a pronounced peak near 300 °C. These (hydro)sulfide complexes account for gold solubility ranging from a few tens of ppb to a few tens of ppm in natural sulfide fluids, depending on the fluid pH. Thermodynamic calculations also indicate that, in addition to (hydro)sulfide species and the hydroxide complex, AuCl2- significantly contributes to Au mobility in high-temperature acidic chloride fluids. Based on new experimental data and prior studies using solubility and X-ray absorption spectroscopy methods, other gold complexes including mixed Au-HS-Cl, Au-HS-S3- species, and complexes with alkali metal cations, are deemed redundant. Above 250 °C, the influence of chloride salts on gold solubility can be accurately modeled using a simple extended Debye-Hückel equation with the term bγ·I = 0. The Setchenov coefficient bn = 0 suffices for calculating the activity coefficients of neutral species. This streamlined thermodynamic model aligns closely with earlier experimental work by Terry Seward and his team, effectively describing the state of Au in all types of natural fluids where Au exists in the 1+ oxidation state, under any set of P-T-f(O2)-f(S2)-compositional parameters.

Cation exchange to montmorillonite induces selective adsorption of amino acids

Concentrating simple organic molecules, such as amino acids, in the adsorbed phase could have been an early step in prebiotic evolution towards more complex bio-macromolecules on the early Earth. Smectite clay minerals represent potential selective sorbents for prebiotic molecules because of their negative structural charge and high surface area. This study evaluated the adsorption behavior of amino acids to montmorillonite, a well-characterized smectite, at varying pH and fluid compositions. At both pH 5 and 7 in a sodium chloride fluid, amino acids with basic sidechains (L-arginine and L-lysine), which are primarily cationic under these conditions, were selectively adsorbed to montmorillonite with Langmuir constants much greater than amino acids that were predominantly zwitterionic or anionic in solution. On average, the Langmuir constants for the cationic amino acids were 30 (pH 5) and 50 (pH 7) times greater than the constants for zwitterionic amino acids and 120 (pH 5) and 80 (pH 7) times greater than the constants for L-glutamic acid. Under the same pH conditions in a magnesium chloride solution, the adsorption of L-arginine and L-lysine was substantially inhibited with Langmuir constants ∼ 10 times smaller. These observations suggest that cation exchange is the dominant adsorption mechanism for amino acids on montmorillonite. X-ray diffraction and infrared spectroscopy indicate that L-arginine and L-lysine enter the smectite interlayer where the protonated amino sidechain has the strongest interactions with the mineral surface, further supporting adsorption driven primarily through electrostatic interactions. Therefore, smectites on the early Earth may have selectively concentrated cationic amino acids, providing a potential template for the polymerization of α-amine linked peptides.

The Ak-Sug Porphyry Copper–Gold–Molybdenum Deposit, East Sayan: Noble Metal Mineralization, PT-Parameters, and Composition of Ore-Bearing Fluid

Ore mineralization of the Ak-Sug Porphyry Copper–Gold–Molybdenum deposit formed during three stages: 1) porphyry-copper mineralization with simple sulfides in quartz–sericite and quartz–sericite–chlorite metasomatites, 2) subepithermal Au–Bi–Te–Pd-quartz mineralization in quartz–sericite metasomatites, and 3) intermediate-sulfidation Au–Ag mineral assemblages with selenides, tellurides, and Sb and As sulfosalts in argillisites. Fluid inclusion studies (microthermometry, Raman spectroscopy) of quartz and mineral thermometry (an assemblage of Au and Ag tellurides) showed that porphyry copper and subepithermal mineralization precipitated from hydrocarbon–aqueous–chloride (Na–K ± Fe) fluid with salinity of 20.1–32.8 wt % NaCl eq. at 435–375°C and hydrocarbon–aqueous–chloride (Na–K ± Fe ± Ca ± Mg) fluid with salinity of 7.5–15.0 wt % NaCl eq. at 415–325°C, respectively. The epithermal mineral assemblages precipitated at ∼0.55 kbar from hydrocarbon–aqueous–chloride (Na–K ± Fe ± Ca ± Mg) fluid with salinity of 1.4–12.6 wt % NaCl eq. at 370–200°C. The latest low-temperature (240–190°С) and diluted (3.5–4.9 wt %) fluids are characterized by variations in Na and K chlorides; Fe2+, Fe3+, Ca, and Mg carbonates; and Na, K, and Mg sulfates. The S isotopic composition of the fluid of different mineral assemblages varies from –2.7 to +0.3‰ and suggest that they are derivatives of a single porphyry system. The δ18О values of the fluid of porphyry copper (7.4‰) and subepithermal (7.0‰) stages indicate its magmatic genesis, whereas those of the epithermal stage (from +1.2 to +7.2‰) are evident of mixing of magmatic fluid and meteoric waters (from +0.4 to +5.7‰). Our isotopic data, combined with mineralogical–geochemical peculiarities and formation conditions of ores, provide tracing the principles of the evolution of mineral assemblages, temperatures, composition, and fluid salinity at the Ak-Sug deposit upon the transition from porphyry copper to epithermal stage.

The state of Zr and Hf in chloride hydrothermal fluids from in situ X-ray absorption spectroscopy

In order to quantify the hydrothermal mobility of Zr and Hf in chloride fluids we performed an investigation of the speciation of these metals by means of in situ X-ray absorption spectroscopy (XAS). The experiments included registration of Zr K-edge X-ray absorption near edge structure/extended X-ray absorption fine structure (XANES/EXAFS), and Hf L1-edge (XANES) and Hf L3-edge (EXAFS) spectra. The capillary method, when the experimental solution together with baddeleyite ZrO2(cr) or HfO2(cr) is sealed inside a silica glass capillary, was used. The spectra were recorded between 320 °C/600 bar and 480 °C/2200 bar (Zr) and at 370 °C/2100 bar (Hf) after the stationary solubility of the solid phase was attained. The aqueous fluid composition varied from 3.8 m HCl to 3.5 m HCl/3.2 m CsCl and 3.3 m HCl/2.2 m NaCl (Zr), and was set to 7.7 m HCl in the case of Hf. The composition of the dominant complexes was determined by means of EXAFS fitting and theoretical XANES modeling as ZrCl3(OH)2−/ ZrCl5(H2O)− and HfCl4OH−/ HfCl5(H2O)−. In Zr complexes the metal-to-ligand distances varied between 2.10 ± 0.06 Å - 2.16 ± 0.06 Å (OH−), 2.22 ± 0.03 Å - 2.32 ± 0.07 Å (OH2), and 2.46 ± 0.02 Å - 2.49 ± 0.02 Å (Cl−) depending on the fluid PT-compositional parameters. In Hf-bearing species the average HfO distance is 2.07 ± 0.12 Å, and the HfCl distance is 2.43 ± 0.03 Å. Both the distances are slightly shorter compared to the interatomic distances in Zr complexes. Higher number of Cl ligands and shorter metal-to-ligand distance determined for Hf complexes mean higher affinity of Hf to oxygen-bearing ligands and chloride ion, which can result in separation of Zr and Hf in hydrothermal processes. Reactions of the dissolution of Zr- and Hf-bearing minerals imply that both ionic associate HCl(aq) and ion Cl− are necessary for the formation of the negatively charged complexes. The region, that best satisfy these conditions, is located between ca. 300 and 450 °C. At higher temperature the neutral Zr/Hf-OH-Cl complexes can support the hydrothermal mobility of these metals. The complexation mechanisms determined for Zr and Hf demonstrate that deep chloride fluids can play an important role in mobilization and separation of these metals in subduction zones and in the fluid-rock interaction processes.

ВЛИЯНИЕ ИММУНОМОДУЛИРУЮЩЕЙ ТЕРАПИИ С ИСПОЛЬЗОВАНИЕМ ДЕЗОКСИРИБОНУКЛЕАТА НАТРИЯ НА МИКРОБИОТУ РОТОГЛОТКИ У ДЕТЕЙ C РЕКУРРЕНТНЫМИ РЕСПИРАТОРНЫМИ ИНФЕКЦИЯМИ В ВОЗРАСТЕ 1–6 ЛЕТ

Respiratory infections are one of the leading diseases currently and almost 2/3 of these infectious processes occur in childhood. The pathogenesis of recurrent respiratory infections is based on the failure of the links of the immune system, mainly caused by a violation of the immune homeostasis of the mucous membranes of the nasopharynx and oropharynx. The purpose of this research was to determine the effect of the immunomodulatory therapy using sodium deoxyribonucleate on the microbiota of the oropharynx in children with recurrent respiratory infections. A single-center randomized placebo-controlled closed experimental study was performed in 90 pediatric patients with recurrent respiratory infections aged 1 to 6 y/o in May 2021-Nov. 2021 on the basis of the private medical center “Center for Modern Pediatrics” located in Voronezh, Russia. The main group consisted of 46 (23 boys and 23 girls aged 4 [3; 5] y/o) who had been given the sodium deoxyribonucleate drug nasally for 30 days. The control group of 44 (22 boys and 22 girls aged 4 [3; 5] y/o) had been given a placebo (a sterile 0.1% sodium chloride fluid) according to the same prescription scheme. The concentration of secretory immunoglobulin was determined by the enzyme immunoassay; the composition of the microbiota was studied by the genetic sequencing of the 16S ribosomal RNA gene. All of the participants in both groups were examined twice: at the start of the study and 90 days after. A statistically significant decrease in the relative amount of Proteobacteria and an increase in the relative amount of Firmicutes and Actinobacteriota, an increase in the concentration of sIgA was found against the background of the use of the drug, which in tis turn indicates an increase in the activity of mucosal immunity (p<0.001). Conclusion: thus, the use of sodium deoxyribonucleate in children aged 1 to 6 years old with recurrent respiratory infections leads to a statistically significant decrease in the relative amount of Proteobacteria and an increase in the relative amount of Firmicutes and Actinobacteriota in the oropharynx; increased activity of mucosal immunity, as evidenced by an increase in the concentration of sIgA.

Hydrothermal Alteration in the Nevados de Chillán Geothermal System, Southern Andes: Multidisciplinary Analysis of a Fractured Reservoir

The interplay between a heat source, primary plus secondary permeability, and hydrothermal fluids makes geothermal systems a highly dynamic environment where evolving physico-chemical conditions are recorded in alteration mineralogy. A comprehensive characterization of hydrothermal alteration is therefore essential to decipher the major processes associated with geothermal system development. In this study, we defined the hydrothermal mineralogical evolution of the Nevados de Chillán Geothermal System (NChGS), located in the Southern Volcanic Zone (SVZ) of the central Andes, where the regional framework of the system is formed by a direct association with a currently active volcanic complex, a favorable structural control, and vertically inhibited fluid circulation. To characterize the secondary mineralogy present in the NChGS, we integrated optical petrography, Scanning Electron Microscopy (SEM) observations, X-ray Diffraction (XRD) analysis, and microthermometric measurements along a drill core with a depth of 1000 m at the Nieblas-1 well. These mineralogical approaches were combined with a structural field analysis to highlight the relevance of multidisciplinary study in understanding active geothermal systems. The results indicated that the evolution of the system involved four paragenetic stages, with the main processes in each phase being the heating, boiling, and mixing of fluids and re-equilibration to new physico-chemical conditions. Additionally, three hydrothermal zones were recognized: an upper argillic section, an intermediate sub-propylitic zone, and a deep propylitic domain. Sampled thermal springs are characterized by pH values of 2.4–5.9 and high SO4= concentrations (>290 ppm). These acid-sulfate steam-heated waters suggest the contribution of primary magmatic volatiles to the hydrothermal system. Alunite recorded in the alteration halos of veinlets presents at depths of 170–230 m denote the circulation of acidic fluids at these levels which were favored by reverse faults. These findings indicate that, at this depth range, the condensation of magmatic volatiles into shallow aquifers controls the recharge area of the superficial thermal manifestations. Conversely, deep-seated hydrothermal fluids correspond to near-neutral chloride fluids, with salinities ranging from 0.1 to 6.9 wt.% NaCl eq. The distribution of illite/smectite and chlorite/smectite mixed-layered minerals outline the presence of a significant clay cap, which, in this system, separates the steam-heated domain from the deep hydrothermal realm and restricts fluid circulation to existing permeable channels. Our mineralogical and structural study provides critical data for the interpretation of heat–fluid–rock interaction processes in the NChGS. The interplay between hydrothermal fluids and active faults is also discussed in the context of the complex of geological processes in active geothermal systems along the Chilean Southern Volcanic Zone.

Comparative Experiments on the Role of CO2 in the Gold Distribution between Pyrite and a High-Salinity Fluid

Experimental studies were conducted to identify the physical and chemical features of gold’s behaviour in hydrothermal processes linked to ore formation and involving CO2 in oxidized deposits. With the aid of the autoclave method, in a temperature range of between 200 and 400 °C, the isochoric dependences of the PVT parameters of concentrated sulphate chloride fluids were plotted, both in the presence and absence of CO2. Our experiments established that concentrated sulphate–chloride fluids (22 wt % Na2SO4 + 2.2 wt % NaCl) that lack CO2 are characterized by a wide supercritical temperature range, with homogenization temperatures of between 250 and 325 °C. In the presence of CO2, the same type of fluids showed heterogenization at a molar fraction of XCO2 = 0.18 (t = 192 °C, P = 176 bar). The process of homogenization for these low-density and high-salinity fluids was impossible at temperatures between 375 and 400 °C and at pressures between 600 and 700 bar. The behaviour of gold was studied during its interaction with a basic composition fluid of sulphate–chloride. We applied the autoclave method under the conditions of a simultaneous synthesis of pyrite and gold dissolution (metallic Au), at a temperature of 340 °C and at a pressure of 440 bar. High Au concentrations (up to 4410 ppm of Au in CO2-bearing fluids) were attained at high gold solubilities (up to 13.5 ppm in the presence of CO2), owing to the process of Au reprecipitation within the pyrite phase. We did not detect Au in the pyrite when we used the XRD or SEM methods, which suggested that it might be present as invisible gold. High values of the distribution coefficient (KD = CAu(solid)/CAu(solution)) in the fluids lacking (KD = 62) and bearing CO2 (KD = 327) empirically confirmed the possibility that gold concentrates in pyrite in structurally non-binding forms.

Chalcocite Cu2S solubility in aqueous sulfide and chloride fluids. Thermodynamic properties of copper(I) aqueous species and copper transport in hydrothermal systems

The most important Cu reserves, including ores of porphyry deposits, were formed by Cl- and S-bearing hydrothermal fluids transporting and depositing metals within the magmatic-hydrothermal ore systems. In order to determine the state of Cu in the fluids, we measured the solubility of chalcocite Cu2S at 350 and 450 °C, 500 and 1000 bar. The concentration of H2S varied from 0.08 to 0.4 m [mol⋅(kg H2O)−1], NaOH – from 0 to 0.2 m, NaCl + HCl – from 0.01 to 4 m. The solubility of chalcocite can be described by the reactions:0.5 Cu2S(cr) + 0.5 H2S(aq) = CuHS(aq) log K°CuHS = −3.99 ± 0.07 (350 °C/500 bar)−4.61 ± 0.09 (450 °C/500 bar), −4.26 ± 0.11 (450 °C/1000 bar);0.5 Cu2S(cr) + 0.5 H2S(aq) + HS− = Cu(HS)2− log K°Cu(HS)2- = −0.85 ± 0.08 (350 °C/500 bar)−0.65 ± 0.11 (450 °C/1000 bar);0.5 Cu2S(cr) + HCl(aq) = CuCl(aq) + 0.5 H2S(aq) log K°CuCl = −3.11 ± 0.70 (450 °C/1000 bar);0.5 Cu2S(cr) + HCl(aq) + Cl− = CuCl2− + 0.5 H2S(aq) log K°CuCl2- = 0.33 ± 0.19 (450 °C/1000 bar)These results, together with data of Rubtsova et al. (2023) on the coupled solubility of Cu(cr) and Ag in chloride fluids, demonstrated that a simple extended Debye-Hückel equation describe activity coefficients of charged species at any NaCl concentration up to the solubility limit at near- and supercritical PT-parameters; activity coefficients of neutral species can be calculated with Setchenov parameter equal to zero. The Cu2S(cr) solubility in sulfide-chloride-bearing fluids is consistent with the formation of Cu-Cl complexes which implies that mixed Cu-HS-Cl complexes can be neglected. The experimental values pooled with the reliable literature data were fitted to the HKF (Helgeson-Kirkham-Flowers) model equation of state (EoS). The obtained HKF EoS parameters allow to predict thermodynamic properties of CuHS(aq), Cu(HS)2−, and CuCl(aq) from 25 to 700 °C and from Psat. to 2000 bar, and up to 1000 °C/5000 bar for CuCl2−. The AD (Akinfiev and Diamond) EoS parameters were derived for CuCl(aq). The AD EoS can be used to calculate the CuCl(aq) Gibbs free energy in the low-density fluids (ρH2O < 0.35 g⋅cm−3) up to 700 °C. The obtained thermodynamic data imply that CuCl2− predominates in high-density ore-forming fluids (ρH2O > 0.35 g⋅cm−3) of total chloride content >0.1 wt% up to the NaCl saturation limit. The hydrosulfide complexes are the main forms of Cu occurrence in the fluid with concentration of dissolved chlorides <0.1 wt% equilibrated with silicate mineral assemblages (e.g., K-feldspar-muscovite-quartz, pH is near-neutral). However, their concentration in the presence of Cu-bearing sulfides is low (< 0.5 ppm at 500 °C/1500 bar) and decreases with temperature decreasing.

Study on leaching behavior differences of rare earth elements from coal fly ash during microwave-assisted HCl leaching

ABSTRACT Coal fly ash (CFA) as a potential resource for rare earth elements and yttrium (REY) has attracted extensive attention over the past few years. This paper focuses on studying microwave systems for the leaching of REY from CFA. Leaching parameters including hydrochloric acid (HCl) concentration, microwave heating time, microwave heating rate, and temperature were assessed. The optimal recovery of 74.91% REY, 86.77% light rare earth elements (LREY), and 34.79% heavy rare earth elements (HREY) are obtained at the conditions of 3 M HCl, T = 220°C, heating rate 39°C/min, and leaching time 30 min. The closed microwave system produces hydrogen chloride fluid or hydrogen chloride gas that is easier to react with CFA than hydrogen ions. It was revealed by the analysis of XRD, particle size, porosity, and SEM that fracture development benefits the entrance of leaching reagents into the inner layer of CFA. A positive linear correlation was found between leaching efficiency and REY3+ ionic radius. The stability of the REY-O bond also remains consistent with the ionic radius, leading to behavior differences during the leaching. This work was targeted to provide a theoretical and technological foundation for microwave-assisted HCl leaching for the extraction of REY in CFA.

Conditions of formation and sources of fluids of the birthplace of barren residential quartz of hydrothermal-metamorphogenic-metasomatic and hydrothermal-metamorphogenic genesis (Middle and South Urals)

The paper considers the conditions of quartz formation of hydrothermal-metamorphogenic-metasomatic and hydrothermal-metamorphogenic genesis of deposits and manifestations of the Middle and Southern Urals based on the study of fluid inclusions by methods of thermobarogeochemistry, ion and gas chromatography. It is established that the studied quartz objects are formed in a wide temperature range, against the background of insignificant differences in pressure values. It is shown that the temperatures of mineral formation in deposits of hydrothermal-metamorphogenic-metasomatic genesis vary from 440-230 ° C at a pressure of 1.2-1.4 kbar. The formation of these veins occurred with the participation of K-Mg-Fe-chloride fluid with a salinity of 1.2-8.7 wt. % NaCl-eq., depleted Mg and Fe due to the deposition of magnesia-ferruginous carbonates. A typomorphic feature of hydrothermal-metamorphogenic-metasomatic quartz is the high values of boron associated with the placement of quartz veins among pegmatoids and the presence of boron-containing mineral inclusions on quartz-vein objects. Veins of hydrothermal-metamorphogenic genesis were formed when the crack system was filled with quartz with the participation of a substantially K-Na chloride fluid (0.2-15.5 wt. % NaCl-eq.), at homogenization temperatures of 435-335 ° C and a pressure of 1.3-2.3 kbar. In the composition of fluid inclusions of hydrothermal-metamorphogenic-metasomatic quartz, the sum of "harmful" components (H2O, CO2, CH4, Cl, B, Na, K, Mg and Li) is less than in hydrothermal-metamorphogenic quartz. The studied quartz deposits and veins were formed in the range of temperatures and pressures not higher than the green shale stage during several successive stages: the formation of quartz veins – in a more high-temperature hydrothermal stage, while subsequent changes in quartz veins occurred under the influence of metamorphism processes, with a decrease in temperature. Subsequent changes are associated with the appearance of fracturing, cataclysm and recrystallization of quartz bodies with a decrease in grain size.

Geochemistry characteristics of the hungayono geothermal area for the development of clean energy in gorontalo province

Geothermal energy has great potential to provide clean energy so that the Sustainable Development Goals (SDGs) can be achieved. The purpose of this study was to identify the geochemical characteristics of the geothermal fluid in the Hungayono area. Geothermal fluid sampling is performed at two points of manifestation which have the highest temperature. The cation and anion testing of geothermal fluid using Atomic Absorption Spectrophotometer (AAS) and isotope testing using the Picarro Water Isotope Analyzer. Data analysis using Giggenbach diagrams. Hot spring temperatures are 54 - 60°C. The deposits at the point of manifestation are iron oxide with neutral fluid pH. Based on the results of the analysis of cations, anions, and isotopes, the Hungayono geothermal fluid is a type of chloride fluid that has been mixed with meteoric water. Based on the geothermometer calculation, reservoir temperature is 232-234°C. Hungayono Geothermal is a type of system with moderate to high concentration.

The Ulug-Sair Gold Occurrence (Western Tuva, Russia): Mineralogy, Ore Genesis, and S-O Isotope Systematics

Ulug-Sair Au-Bi-Te-Se mineralization is one prospect for native Au in the Western Tuva, and its origin remains debated. Mineralization consists of gold–sulfide–quartz veins in the host sedimentary rocks (conglomerates, siltstones, shales), quartz–tourmaline, and quartz–carbonate–sericite–altered rocks. To determine its origin, we examined the mineralogical–geochemical features, formation conditions, and fluid sources of the Ulug-Sair ore. A mineralogical–geochemical investigation outlines two substages with Au: an early gold–sulfide–quartz with pyrite, chalcopyrite, galena, gold, and electrum; and a late gold–telluride–sulfide–quartz, characterized by the presence of Bi-bearing minerals (AgBiTe, Bi2Te2Se, Cu3BiS3, Bi), tellurides (Au and Ag), Se-tellurides (Ag and Bi), and selenides (Au, Ag, and Hg). The paragenesis of Au–Ag tellurides, and fluid inclusion study data (microthermometry, Raman spectroscopy, LA-ICP-MS, and crush leach analysis (gas and ion chromatography, ICP-MS) in quartz showed that quartz–tourmaline-altered rocks were formed by an aqueous Mg–Na–K-chloride fluid with a salinity of 8–10 wt % NaCl eq. at 325–370 °C, whereas the host quartz–carbonate–sericite-altered rocks were formed from CO2–H2O fluid containing CH4 and N2, with a salinity of 0.18–6.1 wt % NaCl eq. at 200–400 °C. Gold-bearing mineral assemblages were formed at P ~ 0.75–1.0 kbar (~2.3–3 km) due to CO2–H2O chloride (Na–K ± Fe, Mg) fluid with CH4, Na2SO4, and Na2B2O5, and salinities 1.7–12.5 wt % NaCl eq. at temperatures decreasing from 360 up to 115 °C (gold–sulfide–quartz veins—360–130 °C, and gold–telluride–sulfide–quartz veins—330–115 °C), and variable fO2, fS2, fSe2, and fTe2. Results of the investigation of the isotope composition of S in pyrites indicates the magmatic origin of the fluid (δ18SH2S fluid from −0.4 to +2.5‰). The stable O isotope data in quartz indicates that, at an early substage, the formation of ore involved a fluid of magmatic and metamorphic origin (from +8.2 to +11.6‰), and, in the later substage, multiple sources of hydrothermal fluids (from +3.1 to +10.4‰), including magmatic-derived, metamorphic-derived, and meteoric waters. These data, in conjunction with structurally controlled mineralization, point towards similarities of the Ulug-Sair ore system with orogenic gold deposits.

A protocol to investigate the stability of 0.9% sodium chloride IV fluid bags in the prehospital setting of Qatar

Background: 0.9% sodium chloride (NaCl) fluid bags are commonly stored in ambulances. Despite that the ambulances normally use air-conditioning during operational shifts, NaCl bags are exposed to deviations from the controlled environmental conditions that could affect their integrity1,2, as all ambulances are not constantly in use. Although stress tests performed in a laboratory Binder Convection Oven3 showed that NaCl maintained its stability, these findings need to be validated. This study aims to develop a protocol to evaluate the thermal stability of NaCl under real-life conditions in Qatar. Methods: Key aspects were considered to subject the research samples to the routine environmental conditions under which NaCl bags are stored in ambulances. The study bags are used for research purposes only, thus should not be used on patients (to avoid hindering the work of paramedics) and need to be tested after various exposure durations. Results: The agreed-upon study protocol is to be replicated on 5 ambulances over 12 months and includes 4 collection cycles of three 500 mL NaCl study bags and three 10 ml NaCl vials following different exposure durations (Table 1). Hence, 12 NaCl bags and 12 vials marked “for research-use-only” will be stored in a locked cabinet in the ambulance patient compartment alongside a temperature and humidity data logger taking measurements every 30 minutes (Figure 1). Control samples will be stored under manufacturer&apos;s recommended conditions. Following each collection cycle from the 5 ambulances and controls, samples will be stored at 4°C and protected from light until being visually inspected (for discoloration, turbidity, bulging), diluted, and tested using ion-exchange chromatography to measure sodium and chloride levels. Conclusion: This study performed under real-life conditions will help determine the effect of exposure to actual ambulance operational conditions on NaCl bags and may have a significant impact on how they are handled in the prehospital setting in countries with a hot/arid climate.

Enteral Sodium Chloride Supplementation and Fluid Balance in Children Receiving Diuretics.

The use of sodium chloride (NaCl) supplementation in children being prescribed diuretics is controversial due to concerns that supplementation could lead to fluid retention. This is a single-center retrospective study in which fluid balance and diuretic dosing was examined in children prescribed enteral NaCl supplements for hyponatremia while receiving loop diuretics. The aim of this study was to determine whether significant fluid retention occurred with the addition of NaCl. Fifty-five patients with 68 events were studied. The median age was 5.2 months, and 82% were hospitalized for cardiac disease. Daily fluid balance the seven days prior to NaCl supplementation was lower than the seven days after, with measurement of: median 17 mL/kg/day (7–26) vs. 22 mL/kg/day (13–35) (p = 0.0003). There was no change in patient weight after supplementation (p = 0.63). There was no difference in the median loop diuretic dose before and after supplementation, with the diuretic dose in furosemide equivalents of 3.2 mL/kg/day (2.3–4.4) vs. 3.2 mL/kg/day (2.2–4.7) (p = 0.50). There was no difference in the proportion of patients receiving thiazide diuretics after supplementation (56% before vs. 50% after (p = 0.10)). NaCl supplementation in children receiving loop diuretics increased calculated fluid balance, but weight was unchanged, and this was not associated with an increase in diuretic needs, suggesting clinicians did not consider the increase in fluid balance to be clinically significant.

Serum Sodium Concentration and Mental Status in Children With Diabetic Ketoacidosis.

Diabetic ketoacidosis (DKA) is typically characterized by low or low-normal serum sodium concentrations, which rise as hyperglycemia resolves. In retrospective studies, researchers found associations between declines in sodium concentrations during DKA and cerebral injury. We prospectively investigated determinants of sodium concentration changes and associations with mental status alterations during DKA. Using data from the Pediatric Emergency Care Applied Research Network Fluid Therapies Under Investigation in Diabetic Ketoacidosis Trial, we compared children who had declines in glucose-corrected sodium concentrations with those who had rising or stable concentrations. Children were randomly assigned to 1 of 4 intravenous fluid protocols that differed in infusion rate and sodium content. Data from the first 4, 8, and 12 hours of treatment were analyzed for 1251, 1086, and 877 episodes, respectively. In multivariable analyses, declines in glucose-corrected sodium concentrations were associated with higher sodium and chloride concentrations at presentation and with previously diagnosed diabetes. Treatment with 0.45% (vs 0.9%) sodium chloride fluids was also associated with declines in sodium concentration; however, higher rates of fluid infusion were associated with declines in sodium concentration only at 12 hours. Frequencies of abnormal Glasgow Coma Scale scores and clinical diagnoses of cerebral injury were similar in patients with and without declines in glucose-corrected sodium concentrations. Changes in glucose-corrected sodium concentrations during DKA treatment are influenced by the balance of free-water loss versus sodium loss at presentation and the sodium content of intravenous fluids. Declines in glucose-corrected sodium concentrations are not associated with mental status changes during treatment.

Native Gold in the Chudnoe Au-Pd-REE Deposit (Subpolar Urals, Russia): Composition, Minerals in Intergrowth and Genesis

Composition of native gold and minerals in intergrowth of the Chudnoe Au-Pd-REE deposit (Subpolar Urals, Russia) was studied using optical microscopy, scanning electron microscopy, and electron microprobe analysis. Five varieties of native gold have been identified, based on the set of impurity elements and their quantities, and on intergrown minerals. Native gold in rhyolites from the Ludnaya ore zone is homogeneous and contains only Ag (fineness 720‰, type I). It is in intergrowth with fuchsite or allanite and mertieite-II. In rhyolites from the Slavnaya ore zone, native gold is heterogeneous, has a higher fineness, different sets and contents of elements: Ag, Cu, 840–860‰ (type II); Ag, Cu, Pd, 830–890‰ (III); Ag, Pd, Cu, Hg, 840–870‰ (IV). It occurs in intergrowth with fuchsite, albite, and mertieite-II (type II), or albite, quartz, and atheneite (III), or quartz, albite, K-feldspar, and mertieite-II (IV). High-fineness gold (930–1000‰, type V) with low contents of Ag, Cu, and Pd or their absence occurs in the form as microveins, fringes and microinclusions in native gold II–IV. Tetra-auricupride (AuCu) is presented as isometric inclusions in native gold II and platelets in the decay structures in native gold III and IV. The preliminary data of a fluid inclusions study showed that gold mineralization at the Chudnoe deposit could have been formed by chloride fluids of low and medium salinity at temperatures from 105 to 230 °C and pressures from 5 to 115 MPa. The formation of native gold I is probably related to fuchsitization and allanitization of rhyolites. The formation of native gold II-V is also associated with the same processes, but it is more complicated and occurred later with a significant role of Na-, Si-, and K-metasomatism. The presence of Pd and Cu in the ores and Cr in fuchsite indicates the important role of mafic-ultramafic magmatism.

Heat Transfer Rate Optimisation of Ionanofluid Based Heat Sink Using ANSYS

Heat dissipation of various electrical and electronic devices has been a significant concern in the current years of modernisation. Many researchers proved that a liquid-cooled microchannel heat sink (MCHS) is an effective way of removing high heat load. Due to ionic liquids’ unique properties such as negligible volatility, non-flammability, high thermal stability, and ionic conductivity, this liquid is combined with nanofluids to synthesise a new class of potential fluids termed Ionanofluids (ionic liquid-based nanofluids). In this research, a numerical simulation of fluid flow and heat transfer characteristics of MWCNT (Multiwalled Carbon Nanotubes) based Ionanofluids as a coolant in a rectangular-shaped microchannel heat sink is analysed. The Two-step method is used for preparing the studied Ionanofluids consisting of 0.5 wt.% of MWCNT nanoparticles ultra-sonicated with a mixture of propylene glycol and 1-Butyl-3-methylimidazolium chloride ([Bmim][Cl]-ionic liquid) fluids. Copper micro channelled heat sink comprising 1 m channel height, 25 μm of channel diameter, and 0.7 m channel width is modelled and simulated with ANSYS-Fluent. The results showed that the heat transfer coefficient increases about 11.4% while the thermal resistance decreases about 15.18% by using the proposed ionanofluids with the concentration of 0.5 wt.% at Re=2000 compared with that of an MCHS with propylene glycol. Moreover, the pressure drop along the studied MCHS increased up to a maximum of 30 kPa for higher heat gradients. Ionanofluids decreased the thermal resistance and temperature difference between the heated surface of the MCHS and Ionanofluids inlet to a greater extent when validated with pure base fluid and previous studies. From the simulated results, a better cooling performance is observed with Ionanofluids compared to pure propylene glycol (PG) for the proposed microchannel heat sink.

Preparation of the Orange Flavoured “Boba” Ball in Milk Tea and Its Shelf-Life

Boba milk tea is very popular around the world. The “boba” balls in milk tea are usually made of tapioca. Reports on calcium alginate ball encapsulation in fruit-flavoured drinks have rarely been seen. The preparation method for this kind ball was studied. The “boba” balls were obtained by membrane formation on the interface through the addition of calcium chloride fluids into a sodium alginate solution. The operation conditions were studied, including drop height, flow velocity, sodium alginate and calcium chloride solution concentration. The diameter, mechanical strength, loading ratio and encapsulation rate of the “boba” balls are discussed. The optimized preparation conditions were as follows: the diameter of adding tube was 8 mm, the drop height was 25 cm, the drop flow rate was 60 mL/min, 1.0% sodium alginate, 1.0% calcium chloride. The prepared “boba” balls were stored at different temperatures. No microorganisms were detected in 90 days, and the sensory quality decreased with storage time. Shelf life was predicted using the Arrhenius equation; when the storage temperature was less than 10 °C, it could be stored for more than 1 year. This preparation technology of “boba” balls has potential for application by milk tea ingredient companies or relevant beverage manufacturing factories.

Vosnesensky Cu-porphyry deposit (Southern Urals): formation conditions, trace elements, sulfur isotopes and fluid sources

The paper shows new fluid inclusion and isotopic-geochemical data for minerals from sulphide-carbonate-quartz veins of Vosnesensky Cu-porphyry deposit. Fluid inclusions were analyzed by means Linkam TMS-600 cryostage equipped with Olympus BX 51 optical microscope; trace element amounts were performed used Agilent 7700x and ELAN 9000 mass-spectrometers; sulphur isotopic composition was analyzed on DeltaPLUS Advantagе mass-spectrometer. We determined that fluid inclusions in quartz were homogenized between 215 and 315 ºС, and in latest calcite, they are 230–280 ºС. Fluids are К-Na water chloride with salinity of 3–12 wt % NaCl-eq. Quartz contain high amounts of Al (184–5180 ppm), K (20.1–1040 ppm), Na (30.2–1570 ppm) and Ti (38.4–193 ppm). The REE distribution spectra of pyrite are characterized by light lanthanides accumulation (LaN/YbN = 3.6–6.44), and negative of Ce anomalies (0.7–0.92) and Eu (0.78–0.99). The Y/ Ho ratio in pyrite varies from 27.6 up to 36.8. The δ34S values in pyrite were –1.01…0.8 ‰, in chalcopyrite – 0.9 ‰. The data testify the Cu-porphyry mineralization of Vosnesensky deposit was formed due to magmatic acid high-aluminous К-Na chloride fluid enriched with light REE in mesothermal environment. We identified the geochemical markers of interaction between fluid and host rocks.