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BackgroundBiofilms in sulfide-rich springs present intricate microbial communities that play pivotal roles in biogeochemical cycling. We studied chemoautotrophically based biofilms that host diverse CPR bacteria and grow in sulfide-rich springs to investigate microbial controls on biogeochemical cycling.ResultsSulfide springs biofilms were investigated using bulk geochemical analysis, genome-resolved metagenomics, and scanning transmission X-ray microscopy (STXM) at room temperature and 87 K. Chemolithotrophic sulfur-oxidizing bacteria, including Thiothrix and Beggiatoa, dominate the biofilms, which also contain CPR Gracilibacteria, Absconditabacteria, Saccharibacteria, Peregrinibacteria, Berkelbacteria, Microgenomates, and Parcubacteria. STXM imaging revealed ultra-small cells near the surfaces of filamentous bacteria that may be CPR bacterial episymbionts. STXM and NEXAFS spectroscopy at carbon K and sulfur L2,3 edges show that filamentous bacteria contain protein-encapsulated spherical elemental sulfur granules, indicating that they are sulfur oxidizers, likely Thiothrix. Berkelbacteria and Moranbacteria in the same biofilm sample are predicted to have a novel electron bifurcating group 3b [NiFe]-hydrogenase, putatively a sulfhydrogenase, potentially linked to sulfur metabolism via redox cofactors. This complex could potentially contribute to symbioses, for example, with sulfur-oxidizing bacteria such as Thiothrix that is based on cryptic sulfur cycling. One Doudnabacteria genome encodes adjacent sulfur dioxygenase and rhodanese genes that may convert thiosulfate to sulfite. We find similar conserved genomic architecture associated with CPR bacteria from other sulfur-rich subsurface ecosystems.ConclusionsOur combined metagenomic, geochemical, spectromicroscopic, and structural bioinformatics analyses of biofilms growing in sulfide-rich springs revealed consortia that contain CPR bacteria and sulfur-oxidizing Proteobacteria, including Thiothrix, and bacteria from a new family within Beggiatoales. We infer roles for CPR bacteria in sulfur and hydrogen cycling. Video Abstract.

Information about the spectra of noble metal minerals obtained by Raman spectroscopy, using the example of a new copper–gold–platinum ore occurrence in the Polar Urals, is presented. For the first time, spectra of temagamite and minerals of the intermediate merenskyite–moncheite series were obtained, and some of the previously detected minerals are refined and confirmed. The prerequisites for new mineral phases of the intermediate series are noted, difficulties in using the method and the need for further development of this area of research are indicated. It is shown that the use of Raman spectroscopy, in controversial cases, complements and often clarifies the data of microprobe studies. [ABSTRACT FROM AUTHOR]

The He isotopic composition and the He and Ne ratio of fluid inclusions in magnetite and pyrite from carbonatite breccias of the Sallanlatva alkali-ultramafic complex of the Kola alkaline province (Northwest Russia) are studied using the step-crushing method. The results indicate the highly likely involvement of fluids from several sources trapped in various proportions during the formation of the Sallanlatva explosive carbonatite breccias. The R/Ra ratio, where R is the measured 3He/4He ratio and Ra of 1.382 × 10–6 is the same ratio of atmospheric air, reaches 2.3, which is a reliable indicator of the presence of mantle gases. A low (1–44) 4He/20Ne ratio allows us to suggest the involvement of atmospheric gases dissolved in paleometeoric waters. A combination of these two facts favors a hypothesis of the phreatomagmatic nature of the studied breccias, i.e., their formation at the expense of interaction between the intruding hot orthomagmatic fluids and meteoric waters with dissolved atmospheric gases. [ABSTRACT FROM AUTHOR]

A novel and concise synthetic method for arenastatin A, a cytotoxic cyclic depsipeptide of marine origin, was developed in this study. The convergent assembly of the four segments, including the cross-metathesis reaction, gave a cyclization precursor, and Fmoc deprotection caused simultaneous macrocyclization. The Corey–Chaykovsky reaction using a chiral sulfur ylide afforded arenastatin A with complete stereoselectivity in the longest linear sequence of seven reaction steps from the known compound. Using this synthetic method, some analogs of segment B were prepared through a late-stage diversification strategy. The simple SN2 reaction of the thiolate toward the tosylate precursor, prepared using almost the same synthetic method as described above, provided the desired sulfide analogs. [ABSTRACT FROM AUTHOR]

Germanium (Ge) is a critical raw material for emerging high-tech and green industries, resulting in considerable recent interest in understanding its distribution and geochemical behavior in ore deposits. In this contribution, the distribution of Ge and related trace elements in the Fule Pb-Zn(-Ge) deposit, South China, is investigated to reveal the distribution of Ge in the hydrothermal ores and during sulfide weathering, using multiple microanalytical techniques, including scanning electron microscopy, electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In the Fule MVT deposit, sphalerite (ZnS) is the most significant Ge-carrier relative to other sulfides, though the five recognized textural types of sphalerite display progressive depletion in Ge from the first sphalerite generation to the late one. In the early stage, sphalerite with fine-grained chalcopyrite inclusions has the highest Ge concentrations, probably accounting for a significant proportion of the total Ge. We interpret that high Ge concentrations in the early sphalerite may be attributable to high Cu activity in the mineralizing fluids. During oxidative weathering, Ge was redistributed from its original host, sphalerite, to the weathering product willemite (Zn2SiO4) rather than smithsonite (ZnCO3), with high levels of Ge (up to 448 μg/g) present in the willemite. The formation of abundant willemite largely prevents the dispersion of Ge during weathering. In principle, willemite-hosted Ge should be fully recoverable, and the Zn-silicate ores may, therefore, be a potential target to meet future demand. This study provides new information on how Ge behaves from sulfide- to weathering-stage in MVT systems, which directly impacts Ge mobility and deportment changes and the development of metallurgical strategies for Ge recovery. [ABSTRACT FROM AUTHOR]

Three decavanadate (V10O28)6- containing compounds were used to test their catalytic activity in the sulfoxidation reaction of diphenyl sulfide using environmentally friendly conditions (low temperature, non-toxic solvent). The compounds of interest for our study, (NH4)2(H2en)2{V10O28}·4H2O, (H2en)3{V10O28}·6H2O and {Li2(H2O)10}(V10O28)(NH4)4, were evaluated, showing good activity in sulfoxidation reaction and leading to complete conversion of the sulfide even after three runs. The tetraammonium decaaqualithium decavanadate, with the formula {Li2(H2O)10}(V10O28)(NH4)4 was obtained through a modified literature method and its structure re-determined and investigated, giving similar results as previously described and confirming the structure of the used material. [ABSTRACT FROM AUTHOR]

Abstract This article is devoted to the synthesis of a new magnetic palladium catalyst that has been immobilized on A-TT-Pd coated-magnetic Fe3O4 nanoparticles. Such surface functionalization of magnetic particles is a promising method to bridge the gap between heterogeneous and homogeneous catalysis approaches. The structure, morphology, and physicochemical properties of the particles were characterized through different analytical techniques, including TEM, FT-IR, XRD, SEM, EDS, TGA-DTG, ICP, and VSM techniques. The obtained Fe3O4@SiO2@A-TT-Pd performance can show excellent catalytic activity for the synthesis of diaryl ethers and oxidation of sulfides, and the corresponding products were obtained with high yields. The advantages of this catalyst include a simple test method, green reaction conditions, no use of dangerous solvents, short reaction time, low catalyst loading, and reusability. Also, the nanocatalyst was easily separated from the reaction mixture with the help of a bar magnet and recovered and reused several times without loss of stability and activity.

Abstract Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies, as well as veiled dielectric-responsive character, are instrumental in electromagnetic dissipation. Conventional methods, however, constrain their delicate constructions. Herein, an innovative alternative is proposed: carrageenan-assistant cations-regulated (CACR) strategy, which induces a series of sulfides nanoparticles rooted in situ on the surface of carbon matrix. This unique configuration originates from strategic vacancy formation energy of sulfides and strong sulfides-carbon support interaction, benefiting the delicate construction of defects-rich heterostructures in MxSy/carbon composites (M-CAs). Impressively, these generated sulfur vacancies are firstly found to strengthen electron accumulation/consumption ability at heterointerfaces and, simultaneously, induct local asymmetry of electronic structure to evoke large dipole moment, ultimately leading to polarization coupling, i.e., defect-type interfacial polarization. Such “Janus effect” (Janus effect means versatility, as in the Greek two-headed Janus) of interfacial sulfur vacancies is intuitively confirmed by both theoretical and experimental investigations for the first time. Consequently, the sulfur vacancies-rich heterostructured Co/Ni-CAs displays broad absorption bandwidth of 6.76 GHz at only 1.8 mm, compared to sulfur vacancies-free CAs without any dielectric response. Harnessing defects-rich heterostructures, this one-pot CACR strategy may steer the design and development of advanced nanomaterials, boosting functionality across diverse application domains beyond electromagnetic response.

The rock composition and ore mineralization of the Malenkiy site located within the Khengur gabbro-dolerite complex of the Pay-Khoy were examined. Petrogeochemical analysis revealed two varieties of the studied rocks: fine-crystalline quartz and medium- and coarse-crystalline quartz containing metagabbro-dolerite. The Y, Zr, and Nb contents suggest that metagabbro-dolerites formed in an intraplate setting from enriched mantle sources during the melting of garnet peridotite, with a small contribution from the melt source of ancient continental crust. Two types of ore mineralization were distinguished: nest- and veinlet-disseminated sphalerite-chalcopyrite-pyrrhotite (type I) and veinlet-disseminated cobaltite-pentlandite-chalcopyrite-pyrrhotite (type II). The most efficient ore mineralization was type II, which is characterized by the presence of both high-temperature cobalt- and nickel-bearing sulfide minerals, as well as low-temperature tellurides of palladium (kotulskite) and silver (hessite).

The paper presents the results of studies of dust residues of snow cover within various climatic zones and copper deposits of the Ural region. Snow cover research is one of the methods for environmental assessment of territories. This concerns the study of dust residues from snow cover samples, as shown by the example of the territories of the Northern and Southern Urals at different stages of work on copper deposits. The initial stage of study and development is considered using the example of porphyry copper deposits in the Chelyabinsk region, where snow samples reveal organic matter in dust residues, typical birch seeds, a small amount of minerals at a low dust load (P ˂ 100 kg/day per km2). For the deposits of the Ivdel region (Northern Urals), the dust residues largely contain organic dust, fragments of ore minerals (pyrite, chalcopyrite) and minerals of volcanic rocks and metasomatic rocks. The maximum value of the dust load is set for the Novo-Shemurskoye deposit currently being developed. A study of dust residues in the zone of influence of the Karabash copper smelter (before its reconstruction) has shown that in some parts of the sanitary protection zone the level of snow cover pollution is very high with dust load values up to 12,633 kg/day per km2, which is determined primarily by the widespread use of crushed copper smelting slag. In general, the study of dust residues of snow cover provides information about both the ecological state of the territories and the mineral composition of the residues, which must be used for practical purposes.

Exfoliation of 2D non‐Van der Waals (non‐vdW) semiconductor nanoplates (NPs) from inorganic analogs presents many challenges ahead for further exploring of their advanced applications on account of the strong bonding energies. In this study, the exfoliation of ultrathin 2D non‐vdW chromium sulfide (2D Cr2S3) by means of a combined facile liquid‐phase exfoliation (LPE) method is successfully demonstrated. The morphology and structure of the 2D Cr2S3 material are systematically examined. Magnetic studies show an obvious temperature‐dependent uncompensated antiferromagnetic behavior of 2D Cr2S3. The material is further loaded on TiO2 nanorod arrays to form an S‐scheme heterojunction. Experimental measurements and density functional theory (DFT) calculations confirm that the formed TiO2@Cr2S3 S‐scheme heterojunction facilitates the separation and transmission of photo‐induced electron/hole pairs, resulting in a significantly enhanced photocatalytic activity in the visible region. [ABSTRACT FROM AUTHOR]

The characterization and evolution of corrosion products deposited on/around MnSs, a typical kind of inclusive particle embedded in AISI 304 stainless steel, was analyzed using a quasi-in-situ method in a 3.5 wt.% NaCl solution. On/around the MnS inclusion, a corrosion product layer with spinel Fe3−xCrxO4 as the main component was formed, with a thickness of several hundred nanometers. Below the layer, there was a cavity layer in which part of the MnS remained, forming secondary pitting along the MnS/matrix boundary. The mechanism of corrosion product deposition and evolution accompanied by MnS dissolution, as well as the characteristics of the corrosion products, are discussed. [ABSTRACT FROM AUTHOR]

Sulfur forms an immiscible liquid upon saturation in magma, and sulfide droplets are commonly found in fresh mid-ocean ridge basalt (MORB). Scanning electron microscopy (SEM) analysis revealed that the fine-grained and weakly phyric MORB samples exhibited hypocrystalline to vitreous textures. Transmission electron microscopy (TEM) of MORB glasses exhibits nanoscale sulfide droplets (10-15 nm) with rounded shapes and smooth edges, showing crystalline and homogeneous composition. Elemental distribution included S, Fe, Cu, and Ni, while Si, Al, and O were lacking. Prior research clarified the immiscibility between sulfide and silicate melts, impacting the size distribution of sulfide droplets. This is the first report on nanoscale sulfide droplets within MORB glasses, and these results suggest that nanoscale sulfide droplets represent the initial phase of sulfide saturation. Such an insight may prove useful in understanding how siderophile and chalcophile elements behaved during sulfide crystallization. In addition, this study determines the immiscibility of sulfides and silicate melts that occur in the early nanometer stage. Therefore, it is speculated that immiscibility phenomena may occur in the nanometer stage during magma evolution. [ABSTRACT FROM AUTHOR]

Flavin-containing monooxygenase from Methylophaga sp. (mFMO) was previously discovered to be a valuable biocatalyst used to convert small amines, such as trimethylamine, and various indoles. As FMOs are also known to act on sulfides, we explored mFMO and some mutants thereof for their ability to convert prochiral aromatic sulfides. We included a newly identified thermostable FMO obtained from the bacterium Nitrincola lacisaponensis (NiFMO). The FMOs were found to be active with most tested sulfides, forming chiral sulfoxides with moderate-to-high enantioselectivity. Each enzyme variant exhibited a different enantioselective behavior. This shows that small changes in the substrate binding pocket of mFMO influence selectivity, representing a tunable biocatalyst for enantioselective sulfoxidations. [ABSTRACT FROM AUTHOR]

Building blocks have been identified that can be functionalised by sequential nucleophilic aromatic substitution. Some examples are reported that involve the formation of cyclic benzodioxin and phenoxathiine derivatives from 4,5-difluoro-1,2-dinitrobenzene, racemic quinoxaline thioethers, and sulfones from 2,3-dichloroquinoxaline and (2-aminophenylethane)-2,5-dithiophenyl-4-nitrobenzene from 1-(2-aminophenylethane)-2-fluoro-4,5-dinitrobenzene. Four X-ray single-crystal structure determinations are reported, two of which show short intermolecular N–O...N "π hole" contacts. [ABSTRACT FROM AUTHOR]

The application of ultraviolet (UV) light for the decontamination of chemical warfare agents (CWAs) has gained recognition as an effective method, especially for treating hard‐to‐reach areas where wet chemical methods are impractical. In this study, TiO2/Ti was employed as a model catalyst, which was contaminated with 2‐chloroethyl phenyl sulfide (CEPS), and subjected to photocatalytic decontamination using both UVB and UVC light. Additionally, photocatalytic decontamination efficiency by introducing Au, Pt, and Cu onto the TiO2/Ti surface was explored. During the photodecomposition process under UVC light, at least eight distinct secondary byproducts were identified. It was observed that the introduction of overlayer metals did not significantly enhance the photodecomposition under UVC light instead overlaid Au exhibited substantially improved activity under UVB light. Whereas, photodecomposition process under UVB light, only five secondary products were detected, including novel compounds with sulfoxide and sulfone functional groups. This novel study offers valuable insights into the generation of secondary products and sheds light on the roles of overlayer metals and photon wavelength in the photodecontamination process of CWA. [ABSTRACT FROM AUTHOR]

Objectives: Current tuberculosis (TB) control strategies face limitations, such as low antibiotic treatment compliance and a rise in multidrug resistance. Furthermore, the lack of a safe and effective vaccine compounds these challenges. The limited efficacy of existing vaccines against TB underscores the urgency for innovative strategies, such as immunoinformatics. Consequently, this study aimed to design a targeted multi-epitope vaccine against TB infection utilizing an immunoinformatics approach. Methods: The multi-epitope vaccine targeted Ag85A, Ag85B, ESAT-6, and CFP-10 proteins. The design adopted various immunoinformatics tools for cytotoxic T lymphocyte (CTL), helper T lymphocyte (HTL), and linear B lymphocyte (LBL) epitope prediction, the assessment of vaccine characteristics, structure modeling, population coverage analysis, disulfide engineering, solubility prediction, molecular docking/dynamics with toll-like receptors (TLRs), codon optimization/cloning, and immune simulation. Results: The multi-epitope vaccine, which was assembled using 12 CTL, 25 HTL, and 21 LBL epitopes associated with CpG adjuvants, showed promising characteristics. The immunoinformatics analysis confirmed the antigenicity, immunogenicity, and lack of allergenicity. Physicochemical evaluations indicated that the proteins were stable, thermostable, hydrophilic, and highly soluble. Docking simulations suggested high-affinity binding to TLRs, including TLR2, TLR4, and TLR9. In silico immune simulation predicted strong T cell (cytokine release) and B cell (immunoglobulin release) responses. Conclusion: This immunoinformatics-designed multi-epitope vaccine targeting Ag85A, Ag85B, ESAT-6, and CFP-10 proteins showed promising characteristics in terms of stability, immunogenicity, antigenicity, solubility, and predicted induction of humoral and adaptive immune responses. This suggests its potential as a prophylactic and therapeutic vaccine against TB. [ABSTRACT FROM AUTHOR]

Axially chiral thioethers and sulfoxides emerge as two pivotal classes of ligands and organocatalysts, which have remarkable features in the stereoinduction of various asymmetric transformations. However, the lack of easy methods to access such molecules with diverse structures has hampered their broader utilization. Herein, an oxidative kinetic resolution for sulfides using a chiral bifunctional squaramide as the catalyst with cumene hydroperoxide as the terminal oxidant is established. This asymmetric approach provides a variety of axially chiral thioethers as well as sulfoxides bearing both axial and central chirality, with excellent diastereo‐ and enantioselectivities. This catalytic system also successfully extends to the kinetic resolution of benzothiophene‐based sulfides. Preliminary mechanism investigation indicates that the multiple hydrogen bonding interactions between the bifunctional squaramide catalyst and substrates play a crucial role in determining the enantioselectivity and reactivity. [ABSTRACT FROM AUTHOR]

Over the past six decades, carbonyl sulfide (COS) in terrestrial ecosystems has been extensively studied, with research focusing on exploring its ecological and environmental effects, estimating source–sink volume, and identifying influencing factors. The global terrestrial COS sink has been estimated to be about 1.194–1.721 Tg a−1, with the terrestrial sink induced by plants and soils 0.50–1.20 Tg a−1, accounting for 41%–69% of the total. Hence, the role of plants and soils as COS sinks has been extensively explored. Now we know that factors such as the activity of carbonic anhydrase (CA), leaf structural traits, soil microbial activity, and environmental factors play significant roles in the COS budget. Developments in observational techniques have also made important contributions to the COS budget. This paper provides an overview of the research progress made on COS based on a comprehensive review of the literature. Then, it highlights the current research hotspots and issues requiring further exploration. For instance, it has been demonstrated that there are still significant uncertainties in the estimation of COS sources and sinks, emphasizing the need for further exploration of COS measuring techniques. This review aims to provide comprehensive guidance for COS research in terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

The primary focus of this research is to conduct a comprehensive exploration of the preparation and description of a thin film composed of bimetallic sulphide, NiZr2S4. The fabrication process involved the utilisation of diethyldithiocarbamate, employing physical vapour deposition. To gain insights into the material's properties, an array of analytical techniques was employed to investigate its structure, morphology, and optical characteristics. A well-defined crystalline assembly with an approximate crystallite size of 42 nm, corresponding to a crystallinity of 77% was observed. Optical properties were evaluated to determine the material's bandgap energy at 2.7 eV. Through X-ray photoelectron spectroscopy, distinct core level peaks associated with Zr 3d, Ni 2p, and S 2p were identified, providing perceptions into the elemental configuration and chemical bonding of the thin film. Electrochemical properties were assessed through voltammetry measurements, revealing a notable specific capacitive performance of 543 Fg−1. The thin film exhibited remarkable stability over multiple cycles, putting it as a highly auspicious contender for various energy storage devices. Furthermore, extensive investigations were shown to evaluate the photocatalytic capabilities of the fabricated material, explicitly its efficiency in degrading various environmental pollutants. These significant findings underscore the versatility of bimetal sulphide thin films, spreading their potential beyond energy storage and paving the way for further research and technological advancements in areas such as photocatalysis and beyond. [ABSTRACT FROM AUTHOR]

The Jinchanghe Pb-Zn polymetallic deposit is a representative distal skarn deposit in the Baoshan block. Due to limited research on the sources of ore-forming metals and trace elemental geochemistry of sulfides, the sources and mineralization environments of the Jinchanghe skarn Pb-Zn polymetallic deposit are still controversial. In this study, copper and sulfur isotopes and trace elements of sulfides from the Jinchanghe Pb-Zn polymetallic deposit were analyzed to reveal the sources of ore-forming materials and the ore-forming environments. The trace elemental analysis results show abundant Co, Ni, Mn and Se elements, and less As, Tl and Sb elements dominantly enter pyrite by isomorphic substitution, except for some Zn and Cu that occur as sulfide inclusions in Py1. Abundant Fe and Mn elements could substitute Zn to enter the sphalerite crystal lattice by the isomorphic substitution mechanism of (Fe2+ + Mn2+) ↔ 2Zn2+, and less Ag and Sb elements could enter the sphalerite by the isomorphic substitution mechanism of (Ag+ + Sb3+) ↔ 2Zn2+. The Cu-S isotopic and trace elemental compositions jointly suggest that the Jinchanghe distal skarn Pb-Zn polymetallic deposit formed from magmatic hydrothermal fluids with a sedimentary host-rock contribution, under mesothermal conditions (260 °C on sphalerite). [ABSTRACT FROM AUTHOR]

The traditional bismuth sulfide concentrate smelting process had the problems of low direct recovery rate of metallic bismuth, low extraction rate of associated valuable metal elements, and SO2 flue gas pollution. In this paper, alkaline smelting has been proposed to realize one-step extraction of metallic bismuth from bismuth sulfide concentrate and immobilization of sulfur in molten salt. The influences of smelting temperature, Na2CO3 addition, and reduced coke dosage on the direct recovery rate of metallic bismuth and sulfur-fixing rate have been investigated in detail. Under the optimum conditions (smelting temperature 900°C, WNa2CO3:WConcentrate = 15%, WCoke:WConcentrate = 10%), the direct recovery rate of metallic bismuth was 95.98% and 99.16% sulfur was fixed in the molten salt. More than 99% Mo and W in the raw material entered into the molten salt, and dissolved in the leach solution in the form of Na2MoO4 and Na2WO4 after water leaching. 20% N235—40% sec-caprylic alcohol—40% sulfonated kerosene organic phase was used as extractant, and 94.48% Mo and 99.49% W were extracted from the organic phase by shaking at 25°C for 10 min with O/A of 1:1. Ammonia was then used for stripping, and the stripping efficiencies of Mo and W reached 96.18% and 93.85%, respectively. [ABSTRACT FROM AUTHOR]

For decades, there has been debate surrounding the transport of dense metal-rich sulfide liquid in mafic magmas. This topic is crucial to understanding the genesis of valuable resources of nickel, copper, and platinum-group elements, which are essential for a sustainable, emission-free energy future. Recent studies of mineralized mafic magmas suggested that gas bubbles adhere to sulfide globules, reducing their density and favoring upward transport. While this hypothesis may explain sulfide mobility in near-surface magmatic environments, it is at odds with key mineralogic and textural observations and does not explain how long-distance sulfide transport operates. Here, we suggest an alternative hypothesis that builds on previous observations, focusing on the interaction between carbonate melt and sulfide liquid. We demonstrate experimentally that carbonate melt wraps sulfide globules forming a relatively mobile pair that may mediate metal-rich sulfide transport from mantle to crust. [ABSTRACT FROM AUTHOR]

To receive a high-quality welding structure of high-strength S700MC steel for applications in the automotive industry, newly developed electrode wires with increased silicon and manganese content were used. The strength and structural tests of the obtained joints were performed. In the weld, we identified the beneficial oxides strengthening the joint structure and unfavorable MnS inclusions. The non-metallic inclusions were formed inside the weld. Their arrangement, morphology, and chemical composition is described. A view on the high-temperature mechanisms of the formations included during the welding process with new electrode wires is presented. It was found that the dominant mechanism of the inclusion formation and the temperature of the welding process impact the content and varied morphology of inclusions, thus determining the exploitation time of the welded joints obtained. The obtained MAG joints made S700MC steel, due to the formation mainly of oxide inclusions and a relatively small amount of MnS phase, were characterized by a high value of yield and tensile strength, which makes them a promising solution for the automotive industry, especially against the background of connections from the discussed steel grade presented in the literature. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing efficient catalysts for the selective oxidation of sulfides to sulfoxides using molecular oxygen as the oxidant is a challenging task. Here, we report a novel catalyst comprising a single atom palladium engineered cobalt nanocomposite (denoted as PdCo@NC-800–0.01) for this reaction. The incorporation of single atom palladium effectively transforms an originally inactive cobalt nanocomposite into a highly efficient and selective catalyst for the oxidation of sulfides. This catalyst PdCo@NC-800–0.01 exhibited outstanding performance in the selective oxidation of sulfides to sulfoxides using O 2 as the oxidant in the presence of isobutyraldehyde (IBA) under mild conditions, demonstrating high activity and excellent selectivity for a broad spectrum of sulfides with good tolerance toward various functional groups, including those susceptible to oxidation. Furthermore, the catalyst could be easily recovered and reused up to 10 times without any significant loss in activity and selectivity. Comprehensive characterizations and theoretical calculations revealed that the engineering of cobalt nanocomposite with single atom Pd greatly enhanced the ability to adsorb and activate IBA, leading to the generation of the key acyl radical. This radical then reacted with singlet oxygen 1O 2 derived from molecular oxygen, producing reactive oxygen species peroxy radical, which ultimately promoted the catalytic performance. [ABSTRACT FROM AUTHOR]

Highlights: Mo–MXene/Mo–metal sulfides with semiconductor junctions and Mott–Schottky junctions are designed. Built-in electric field are constructed in semiconductor–semiconductor–metal heterostructure, enhancing dielectric polarization and impedance matching. Density functional theory calculations and Radar cross-section simulations confirmed the excellent electromagnetic wave absorption ability of heterostructures. The exploration of novel multivariate heterostructures has emerged as a pivotal strategy for developing high-performance electromagnetic wave (EMW) absorption materials. However, the loss mechanism in traditional heterostructures is relatively simple, guided by empirical observations, and is not monotonous. In this work, we presented a novel semiconductor–semiconductor–metal heterostructure system, Mo–MXene/Mo–metal sulfides (metal = Sn, Fe, Mn, Co, Ni, Zn, and Cu), including semiconductor junctions and Mott–Schottky junctions. By skillfully combining these distinct functional components (Mo–MXene, MoS2, metal sulfides), we can engineer a multiple heterogeneous interface with superior absorption capabilities, broad effective absorption bandwidths, and ultrathin matching thickness. The successful establishment of semiconductor–semiconductor–metal heterostructures gives rise to a built-in electric field that intensifies electron transfer, as confirmed by density functional theory, which collaborates with multiple dielectric polarization mechanisms to substantially amplify EMW absorption. We detailed a successful synthesis of a series of Mo–MXene/Mo–metal sulfides featuring both semiconductor–semiconductor and semiconductor–metal interfaces. The achievements were most pronounced in Mo–MXene/Mo–Sn sulfide, which achieved remarkable reflection loss values of − 70.6 dB at a matching thickness of only 1.885 mm. Radar cross-section calculations indicate that these MXene/Mo–metal sulfides have tremendous potential in practical military stealth technology. This work marks a departure from conventional component design limitations and presents a novel pathway for the creation of advanced MXene-based composites with potent EMW absorption capabilities. [ABSTRACT FROM AUTHOR]

A new molecular line list covering wavelengths λ > 1  μ m (the 0–10 000 cm−1 range) for the main isotopologue of carbonyl sulphide 16O12C32S is presented. The OCS line list, named OYT8, contains almost 2.5 billion transitions between 2.4 million rotation-vibration energy levels with the total angular momentum up to J  = 223. It is suitable for high-temperature environments up to T  = 2000 K. Line list calculations were performed with the variational nuclear motion code trove in conjunction with a highly accurate, empirically refined potential energy surface and a newly computed ab initio dipole moment surface of OCS. The OYT8 line list is adapted for high-resolution applications by replacing computed energy levels with empirically derived values of OCS where available. Comparisons of the OYT8 line list with other OCS line lists and spectra yields excellent agreement for both strong and weak spectroscopic bands. The increased coverage of the OYT8 line list and the many new spectral features that are available will greatly facilitate the future observation of OCS on exoplanets. Carbonyl sulphide joins a growing number of sulphur-bearing molecules available from the ExoMol database. The OYT8 line list along with the associated temperature- and pressure-dependent molecular opacities can be downloaded from www.exomol.com and the CDS astronomical database. [ABSTRACT FROM AUTHOR]

Thioethers are critical in the fields of pharmaceuticals and organic synthesis, but most of the methods for synthesis alkyl thioethers employ foul-smelling thiols as starting materials or generate them as by-products. Additionally, most thiols are air-sensitive and are easily oxidized to produce disulfides under atmospheric conditions; thus, a novel method for synthesizing thioethers is necessary. This paper reports a simple, effective, green method for synthesizing dialkyl or alkyl aryl thioether derivatives using odorless, stable, low-cost ROCS2K as a thiol surrogate. This transformation offers a broad substrate scope and good functional group tolerance with excellent selectivity. The reaction likely proceeds via xanthate intermediates, which can be readily generated via the nucleophilic substitution of alkyl halides or aryl halides with ROCS2K under transition-metal-free and base-free conditions. [ABSTRACT FROM AUTHOR]

An iodophor-catalyzed direct disulfenylation of amino naphthalenes with aryl sulfonyl hydrazines in water was developed. A series of aryl sulfides were obtained in moderate to excellent yields. The advantages of this green protocol were the simple reaction conditions (metal-free, water as the solvent, under air), the odorless and easily available sulfur reagent, the broad substrate scope, and gram-scale synthesis. Moreover, the potential application of aryl sulfides was exemplified by further transformations. [ABSTRACT FROM AUTHOR]

Data indicating the important role of microorganisms in the formation of nodular monazite (NM) (kularite) of the Kular Range, Republic of Sakha (Yakutia), are presented. The NM contains microorganisms (cyanobacteria) replaced by REE-bearing phosphate (monazite) in the form of stromatolitic microedifices, as well as framboidal Fe sulfides in monazite. The Corg isotopic composition of kularite corresponds to biogenic carbon: the δ13С values vary from –22.2 to –22.3‰. [ABSTRACT FROM AUTHOR]

Copper and iron isotopic signatures in sulfide and silicate minerals are important genetic indicators in magmatic sulfide deposits. Kalatongke is a large‐scale magmatic Cu‐Ni sulfide deposit in the Central Asian Orogenic Belt, and one that experienced multiple stages of magmatism and contamination. It is an ideal deposit in which to study Cu‐Fe isotopic fractionation during multiple stages of magmatism and sulfide mineralization processes. The Kalatongke sulfide orebodies are hosted by three small mafic intrusions in which pyroxene and sulfides (pyrrhotite, pentlandite, and chalcopyrite) are the most common Fe‐rich minerals, and chalcopyrite is the dominant Cu‐rich mineral. Sulfide liquid and silicate melt ▵56FeSul‐Sil (0.03–0.19‰) and ▵65CuCcp‐Sil (−0.78–0.74‰) values are indicative of non‐equilibrium fractionation. Most of the Cu isotope compositions in the sulfide ores at Kalatongke can be modeled as subduction‐ metasomatized, oxidized mantle source‐derived silicate melt (initial δ57Fe = 0.15‰, δ65Cu = −0.07‰) that underwent lower crustal contamination, and then reacted with silicate melt, having an R factor of 100–1,000. Rapid silicate melt and sulfide liquid Fe isotope exchange and re‐equilibration between chalcopyrite and pyrrhotite in the massive ores is reflected in the similarity of their δ56Fe values. Sulfide in disseminated ores shows a range of Fe isotope ratios, influenced by the proportions of monosulfide solid solution (MSS) and intermediate solid solution (ISS) formed. Copper isotopes can be utilized to characterize crustal contamination and silicate melt‐sulfide liquid interaction, while the Fe isotope ratios of sulfide minerals record sulfide liquid segregation and evolution in magmatic sulfide deposits. Key Points: Sulfide δ65Cu and δ56Fe signatures reflect crustal contamination, sulfide and silicate melt reactions, and sulfide liquid segregationCopper isotopes can record the source and crustal contamination, sulfide liquid and silicate melt reaction, and sulfide segregationVarious range of sulfide minerals Fe isotopes influenced by the segregation of MSS and ISS and their ratios [ABSTRACT FROM AUTHOR]

The development of highly efficient sodium‐ion batteries depends critically on the successful exploitation of advanced anode hosts that is capable of overcoming sluggish reaction kinetics while also withstanding severe structural deformation triggered by the large radius of Na+‐insertion. Herein, a hierarchically hybrid material with hetero‐Co3S4/NiS hollow nanosphere packaged into a densified N‐doped carbon matrix (Co3S4/NiS@N‐C) was designed and fabricated utilizing CoNi‐glycerate as the self‐sacrifice template, making the utmost of the synergistic effect of hetero‐Co3S4/NiS with strong electric field and rich reaction active‐sites together with the densified outer‐carbon scaffolds with remarkable electronic conductivity and robust mechanical toughness. As anticipated, as‐fabricated Co3S4/NiS@N‐C anode affords remarkable specific capacity, prolonged cycle lifespan up to 2 400 cycles with an only 0.05% fading each cycle at 20.0 A g−1, and excellent rate feature (354.9 mAh g−1 at 30.0 A g−1), one of the best performances for most existing Co3S4/NiS‐based anodes. Ex situ structural characterizations in tandem with theoretical analysis demonstrate the reversible insertion‐conversion mechanism of initially proceeding with Na+ de‐/intercalation and superior heterogeneous interfacial reaction behavior with strong Na+‐adsorption ability. Further, sodium‐ion full cell and hybrid capacitor based on Co3S4/NiS@N‐C anode exhibit impressive electrochemical characteristics on cycling performance and rate capability, showcasing its outstanding feasibility toward practical use. [ABSTRACT FROM AUTHOR]

We report the synthesis, characterizations, and hydrogen gas sensing of pure and silver (Ag)-doped bismuth sulfide (Bi2S3) nanobelts. The economical synthesis of Bi2S3 was carried out by the sulfurization of bismuth oxide (Bi2O3) using conventional solid-state reaction method. X-ray diffraction and scanning electron microscopy confirmed the synthesis of pure and silver-doped Bi2S3 nanobelts. Hydrogen gas sensing was studied at room temperature through current–voltage (I–V) characteristics. The percentage response of pure Bi2S3 nanobelts was 4.10%, whereas 2.5% silver-doped Bi2S3 showed a response of 24.01% at 26.66 kPa of H2 pressure. Response and recovery times were also analyzed from the dynamic response curves. Pure Bi2S3 nanobelts showed a response time of 8 s and recovery time of 20.4 s, whereas 2.5% silver-doped Bi2S3 nanobelts showed a response time of 6 s and recovery time of 15.2 s. The silver doping improved the reproducibility, selectivity, and stability of the sensor. [ABSTRACT FROM AUTHOR]

Supercapacitors are useful for storing and delivering more energy in smaller footprints. Developing high-energy-density supercapacitors enables more efficient utilization of energy, improved performance, and a means for flexibly addressing diverse energy storage requirements. The electrode materials and the techniques used for their fabrication play a significant role in obtaining the desired operating performance of supercapacitors. The present study employs a novel, simple, scalable, and low-cost fabrication technique to synthesize nickel-cobalt sulfide (NiCo2S4) nanostructures on commercial nickel foam. Prominent morphological and electrochemical characterization techniques were used to assess the structural and operating performance of the synthesized nanostructure. The synergistic effects of nickel and cobalt transition metals resulted in enhanced performance of the nanostructure. The synthesized nanostructure was further employed in a symmetric supercapacitor device. Surface morphological and electrochemical experiments showed an energy density value of 62.8 Wh/kg and retention capacity of 94% even after 8000 cycles. The electrochemical characteristics were validated using electrical experiments as well. The high specific capacitance, faster electron and ion transfer, and improved structural integrity obtained for the supercapacitor indicate its suitability for enhanced energy storage applications. [ABSTRACT FROM AUTHOR]

Arsenic and antimony are impurities that reduce the economic value of concentrates due to the environmental problems they cause. The removal of these impurities by hydrometallurgical means has been highly studied for sulfide copper concentrates using different leaching agents in an alkaline medium (NaClO, H2O2, NaOH, Na2S, NaHS, and S). For a lead–silver concentrate consisting of galena, sphalerite, and pyrite, it was possible to selectively reduce the arsenic content from 1.10% to 0.55% and antimony from 2.41 to 1.04% through the digestion-leaching technique that uses elemental sulfur as a leaching agent in alkaline medium. The adequate powdered sulfur and sodium hydroxide dosage were 336 and 342 kg/t, respectively. The process was carried out at 120 °C with a liquid/solid ratio of 2 in digestion and 5.67 in leaching; the appropriate digestion and leaching time were 20 and 30 min, respectively. The thermodynamics and kinetics of this process turned out to be very complex due to the great variety of simultaneous leaching and precipitation reactions. The digestion process exhibited a mixed kinetic control, where diffusion through the boundary layer and the chemical reaction were the controlling steps with an activation energy of 11.05 kcal/mol. [ABSTRACT FROM AUTHOR]

A commentary on pressure‐induced pre‐lithiation towards Si anodes in all‐solid‐state Li‐ion batteries (ASSLIBs) using sulfide electrolytes (SEs) is presented. First, feasible pre‐lithiation technologies for Si anodes in SE‐based ASSLIBs especially the significant pressure‐induced pre‐lithiation strategies are briefly reviewed. Then, a recent achievement by Meng et al. in this field is elaborated in detail. Finally, the significance of Meng's work is discussed. [ABSTRACT FROM AUTHOR]

The effect of sulfides on the pitting corrosion behavior and film chemistry of 70/30 copper-nickel alloys in aerated seawater was investigated. Sulfides in seawater prevent the formation of protective oxides on the surface of the alloy and alter the morphology and composition of the corrosion products. It results in the corrosion product film consisting of the double layer structure of the loose and porous sulfide-containing outer layer and the dense inner layer. This double-layer structure of the corrosion product film can't alleviate corrosion, but instead accelerates the development of pitting corrosion. The statistical analysis method is used to study the corrosion process of 70/30 copper-nickel alloy in sulfide-containing environment. This work records the trend of pitting corrosion towards the horizontal and longitudinal directions.

Abstract The incomplete combustion of biomass and fossil fuels results in the formation of not only black carbon (BC) but also black nitrogen (BN), the dissolved fractions of which (i.e., DBC and DBN) are important components of dissolved organic matter pool. Relative to DBC, the activity and reactivity of DBN are much less understood. Here, we investigated the catalytic effect of DBN derived from N-enriched biomass in the abiotic transformation of chlorophenols by sulfides. The medium-temperature DBN (450 °C) exhibited 13–144% higher catalytic efficiency than other DBN samples and 9.3 times higher than its DBC counterpart. Both electron paramagnetic resonance spectra and fluorescent probe technique indicated that the attached sulfides contributed to the formation of reactive oxygen species (ROS) as the “primary” radicals by favoring electron transfer from DBN to chemisorbed oxygen, and then the generated ROS reacted with N-oxides in DBN to form reactive nitrogen species (RNS) as the “secondary” radicals. The contribution of RNS to the decay of 2-chlorophenol by DBN450 was up to 72%, much higher than that of ROS and non-radical mechanism. These findings suggest that the catalytic effect of DBN is distinct but no less significant than that of DBC to the abiotic transformation of micropollutants in water/soil systems. Graphical Abstract

This paper presents an analysis of non-metallic inclusions occurring in high-silicon steels containing about 3% Si of terms of their type, volume fraction and morphology. The inclusions were divided into 3 main groups: oxides, sulfides, nitrides which together can also form complex. The work was based on numerous metallographic observations in two sections (longitudinal and transverse to the rolling direction). The study was performed on three casts differing in chemical composition. The analyzed casts were characterized by a different content of non-metallic inclusions, which can be associated with slight differences in chemical composition. The analyzed results showed that the most common inclusions were oxides and nitrides. Sulfides occurred sporadically.

The incomplete combustion of biomass and fossil fuels results in the formation of not only black carbon (BC) but also black nitrogen (BN), the dissolved fractions of which (i.e., DBC and DBN) are important components of dissolved organic matter pool. Relative to DBC, the activity and reactivity of DBN are much less understood. Here, we investigated the catalytic effect of DBN derived from N-enriched biomass in the abiotic transformation of chlorophenols by sulfides. The medium-temperature DBN (450 °C) exhibited 13–144% higher catalytic efficiency than other DBN samples and 9.3 times higher than its DBC counterpart. Both electron paramagnetic resonance spectra and fluorescent probe technique indicated that the attached sulfides contributed to the formation of reactive oxygen species (ROS) as the "primary" radicals by favoring electron transfer from DBN to chemisorbed oxygen, and then the generated ROS reacted with N-oxides in DBN to form reactive nitrogen species (RNS) as the "secondary" radicals. The contribution of RNS to the decay of 2-chlorophenol by DBN450 was up to 72%, much higher than that of ROS and non-radical mechanism. These findings suggest that the catalytic effect of DBN is distinct but no less significant than that of DBC to the abiotic transformation of micropollutants in water/soil systems. Highlights: Dissolved black nitrogen is an overlooked active nano-catalyst in the natural environment. The medium-temperature dissolved black nitrogen exhibited the highest catalytic efficiency. Not only ROS but also RNS were generated in the dissolved black nitrogen-sulfide system. The contribution of RNS to the decay of 2-CP was higher than that of ROS and non-radical mechanism. [ABSTRACT FROM AUTHOR]

Schematic diagram of the whole process for detecting sulfur-containing components in lithium-sulfur batteries, including graded leaching, efficient oxidation and precise quantitative detection. [Display omitted] • A highly effective approach for the graded leaching and precise quantitative detection techniques of sulfur-containing components within Li-S batteries has been successfully developed. The total detection rate of this method for sulfur-containing components in Li-S batteries exceeds 99 %. • Clarify that the presence of lithium polysulfide in the electrolyte after discharge is the main factor for restricting the full utilization of Li-S batteries' capacity, and propose targeted improvement measures. • This study offers a considerably refined and comprehensive methodology for the capacity fading and failure mechanisms assessment of high-energy-density Li-S batteries. Lithium-sulfur (Li-S) batteries are a strong contender for the new-generation battery system to meet the growing energy demand due to their significantly high energy density (2600 Wh/kg) and cost-effectiveness. However, the practical operating conditions yield an initial capacity of less than 80 % of the theoretical capacity, resulting in a limited lifespan and hindering broader application. What's worse, current mechanism, especially the evolution process of sulfides for the initial capacity degradation is not clear due to the practical difficulties of effective separation and detection of sulfur-containing components. Herein, we have developed an instrumental analysis method enabling graded leaching and quantitative determination of sulfur-containing components. This technology achieves a detection precision surpassing 99.11 %, addressing the inherent deficiency in calculating sulfur-containing components using the decrement method. Applying this method reveals that the presence of lithium polysulfides in the electrolyte (26.34 wt%) after discharging is the primary factor causing insufficient capacity utilization in Li-S batteries. This work not only demonstrates the unique behavior of Li-S batteries at high sulfur loading but also provides a systematic evaluation method to guide further research on high-energy-density batteries, and provides theoretical and technical support to promote the development of high-energy, long-life Li-S batteries. [ABSTRACT FROM AUTHOR]

Carbonyl sulfide (COS), a trace gas in our atmosphere that leads to the formation of aerosols in the stratosphere, is largely taken up by terrestrial ecosystems. Quantifying the biosphere uptake of COS could provide a useful quantity to estimate gross primary productivity (GPP). Some COS sources and sinks still contain large uncertainties, and several top-down estimates of the COS budget point to an underestimation of sources, especially in the tropics. We extended the inverse model TM5-4DVAR to assimilate Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite data, in addition to National Oceanic and Atmospheric Administration (NOAA) surface data as used in a previous study. To resolve possible discrepancies among the two observational data sets, a bias correction scheme is necessary and implemented. A set of inversions is presented that explores the influence of the different measurement streams and the settings of the prior fluxes. To evaluate the performance of the inverse system, the HIAPER Pole-to-Pole Observations (HIPPO) aircraft observations and NOAA airborne profiles are used. All inversions reduce the COS biosphere uptake from a prior value of 1053 GgS a -1 to much smaller values, depending on the inversion settings. These large adjustments of the biosphere uptake often turn parts of Amazonia into a COS source. Only inversions that exclusively use MIPAS observations, or strongly reduce the prior errors on the biosphere flux, maintain the Amazon as a COS sink. Inclusion of MIPAS data in the inversion leads to a better separation of land and ocean fluxes. Over the Amazon, these inversions reduce the biosphere uptake from roughly 300 to 100 GgS a -1 , indicating a strongly overestimated prior uptake in this region. Although a recent study also reported reduced COS uptake over the Amazon, we emphasise that a careful construction of prior fluxes and their associated errors remains important. For instance, an inversion that gives large freedom to adjust the anthropogenic and ocean fluxes of CS2 , an important COS precursor, also closes the budget satisfactorily with much smaller adjustments to the biosphere. We achieved better characterisation of biosphere prior and uncertainty, better characterisation of combined ocean and land fluxes, and better constraint of both by combining surface and satellite observations. We recommend more COS observations to characterise biosphere and ocean fluxes, especially over the data-poor tropics. [ABSTRACT FROM AUTHOR]

Reaction OH + OCS → products (1) has been studied in a discharge–flow reactor combined with modulated molecular beam mass spectrometry. The reaction rate constant has been determined under pseudo-first-order conditions through monitoring OH decays in a high excess of OCS: k1 = (2.35 ± 0.25) × 10−12 exp(−(2144 ± 56)/T) cm3 molecule−1 s−1 at T = 365–960 K (the uncertainties represent precision at the 2σ level, the total 2σ relative uncertainty including statistical and systematic errors on the rate constant being 20% at all temperatures). The rate constant of reaction (1) was found to be similar at a total helium pressure of 1, 2, and 8 torr at around 500 K. The SH radical was identified as the primary product of the reaction, and its yield was determined to be about 100% at T = 500 and 750 K. The kinetic and mechanistic data from the present study are compared to previous experimental and theoretical work. [ABSTRACT FROM AUTHOR]

The Baiyun gold deposit is a medium-sized deposit in northeastern Hubei around the southern margin of the Tongbai-Dabie metallogenic belt. However, its genesis has not been determined. The metallogenic process of the Baiyun gold deposit can be divided into three stages: quartz + feldspar, quartz + native gold + electrum + polymetallic sulfides, and quartz + pyrite + calcite + iron dolomite + illite. In this study, LA-ICP-MS was used for in situ trace element and isotope analyses in the main and late ore stage hydrothermal sulfides to evaluate the genesis and evolution of ore-forming fluids. Gold is positively correlated with Ag, Cu, Pb, Zn, and Te and the Co/Ni ratio is greater than 1. The S isotope values of Py1 and Py2 are −0.23–3.04‰ and 1.27–6.09‰, respectively. As mineralization progressed, S isotope values increased. In situ S isotope values of the two types of galena symbiotic with pyrite in the main metallogenic stage are 2.97–3.47‰. In situ Fe isotopic values of pyrite are −0.05–0.82‰; values in the two stages are similar without significant fractionation. We inferred that the Baiyun gold deposit formed via magmatic mineralization related to the subduction of the Pacific Plate during the Yanshanian. [ABSTRACT FROM AUTHOR]

Several gold deposits in the eastern region of Cuba are genetically related to the island arc- and the ophiolitic complex formation. These have been studied and exploited since the time of the Spanish colonization in the mid-sixteenth century. These deposits belong to the Aguas Claras-Guajabales mineral field in the Holguín Province (Cuba) and lie in an elongated zone approximately 15 km in length. The object of this work is to make a methodical, detailed, and chronological review of the geological and mining work carried out in this region, as well as highlight the degree of the previously achieved studies. To realize this, an extensive bibliographic review of all available data, including published reports and articles, as well as unpublished material, was carried out. Moreover, ore mineralogy and petrography were reviewed by thin section analyses from samples from these deposits by petrographic and scanning electron microscopy. The results obtained from this study highlight that the gold mineralization in that area is closely linked to metasomatic processes produced by the circulation of hydrothermal fluids that affected the different volcanic and ultramafic rocks. This study shows that the highest gold contents observed are controlled by the contacts between the different host lithologies with high rheological contrasts. The presence of different alteration styles such as serpentinization, listvenitization, rodingitization, and propylitization have played a primary role in the deposition of gold during mineralization processes. This work could be a very useful exploration guide for future research in this region, as it provides a useful and practical compilation of the characteristics of the mineralization and alteration styles, as well as a precise indication of the spatial position, thicknesses, and contents of the gold-rich horizons. [ABSTRACT FROM AUTHOR]

Persulfides (RSSH/RSS−) participate in sulfur metabolism and are proposed to transduce hydrogen sulfide (H2S) signaling. Their biochemical properties are poorly understood. Herein, we studied the acidity and nucleophilicity of several low molecular weight persulfides using the alkylating agent, monobromobimane. The different persulfides presented similar pKa values (4.6–6.3) and pH-independent rate constants (3.2–9.0 × 10³ M−1 s−1), indicating that the substituents in persulfides affect properties to a lesser extent than in thiols because of the larger distance to the outer sulfur. The persulfides had higher reactivity with monobromobimane than analogous thiols and putative thiols with the same pKa, providing evidence for the alpha effect (enhanced nucleophilicity by the presence of a contiguous atom with high electron density). Additionally, we investigated two enzymes from the human mitochondrial H2S oxidation pathway that form catalytic persulfide intermediates, sulfide quinone oxidoreductase and thiosulfate sulfurtransferase (TST, rhodanese). The pH dependence of the activities of both enzymes was measured using sulfite and/or cyanide as sulfur acceptors. The TST half-reactions were also studied by stopped-flow fluorescence spectroscopy. Both persulfidated enzymes relied on protonated groups for reaction with the acceptors. Persulfidated sulfide quinone oxidoreductase appeared to have a pKa of 7.8 ± 0.2. Persulfidated TST presented a pKa of 9.38 ± 0.04, probably due to a critical active site residue rather than the persulfide itself. The TST thiol reacted in the anionic state with thiosulfate, with an apparent pKa of 6.5 ± 0.1. Overall, our study contributes to a fundamental understanding of persulfide properties and their modulation by protein environments. [ABSTRACT FROM AUTHOR]