Sulfide Formation Research Articles

Electrochemical nucleation and growth model of MoS2 for hydrogen evolution reaction

The electrochemical nucleation of MoS2 from a mixture of sodium molybdate dihydrate (Na2MoO4·2H2O) and sodium sulphide (Na2S·xH2O) aqueous solution on Cu substrate has been investigated. The nucleation and formation of molybdenum sulphide were investigated employing cyclic voltammetry and chronoamperometry studies. The experimental i–t curves observed at various overpotentials were compared to theoretical curves derived for the two limiting situations of the 3D instantaneous/progressive nucleation and growth model, as reported by Scharifker and Hills. The outcome of electrodeposition potential on nucleation rate (A) and nucleation density (N) was calculated from the current–time transients and SEM morphology obtained at − 1.1 V (5.75 × 1014 and 1.86 × 1015) was compared with − 0.9 V, − 1.0 V, and − 1.2 V, respectively. The investigation of the initial stages of the transient current–time relationships developed for MoS2 electrodeposition specified that film formation occurred progressively initially and instantaneous nucleation during the course of time. A HPMoS2 with an average size of 5–65 nm was obtained at -1.1 V and exhibited superior performance towards the hydrogen evolution reaction compared to samples obtained at − 0.9 V, − 1.0 V, and − 1.2 V.

Regenerable nickel catalysts strengthened against H2S poisoning in dry reforming of methane

In this study, alumina-supported bimetallic Ni-Cu and trimetallic Ni-Cu-Ce catalysts were synthesized to improve catalysts resistant to coke formation and sulfur poisoning for dry reforming of methane (DRM). The effects of parameters such as feed composition, synthesis method, and H2S concentration using the catalyst with the best activity were also investigated. To determine the physical and chemical properties of the synthesized catalysts, XRD, N2 adsorption–desorption, TGA-DTA, ICP-OES, SEM-EDX, XPS, and DRIFTS analyses were performed. XRD analysis showed that the fresh Ni-Cu catalysts have elemental nickel and γ-alumina phases in their structures. In addition to these structures, the CeO2 crystal structure was determined for the Ni-Cu-Ce catalyst. Type IV isotherm with H1 hysteresis indicating uniform mesoporous structure was obtained with all the catalysts. The activities of the synthesized catalysts in DRM were performed in the presence of different concentrations of H2S (2 ppm, 50 ppm, and 500 ppm) in a fixed bed reactor at 750 °C using a gas chromatography-equipped system. The alumina-supported 8Ni-3Cu-8Ce catalyst prepared by the impregnation method exhibited a higher and more stable activity comparing the bimetallic Ni-Cu catalyst in the presence of H2S. Adding copper and cerium to the nickel catalyst has a curative effect on resistance to coke formation and sulfur poisoning. Excess CO2 in the feed stream increased the H2S poisoning resistance of the catalyst. To analyze the reactor exit stream in catalytic activity using different feed stream compositions such as H2S+He, H2S+CO2+He, and H2S+CO2+CH4+He, FTIR with a gas cell was used. The formation of carbonyl sulfide (COS) and H2O, which occurs due to the possible reaction between CO2 and H2S, was observed. Regeneration studies showed that the catalyst could undergo regeneration with a low oxygen concentration (0.3 % O2 in He). 8Ni-3Cu-8Ce@SGA, which gave 71 % CH4 conversion in the first minute of the reaction test in the presence of 50 ppm H2S, was regenerated after completely losing its activity at the end of 5 h. 66 % CH4 conversion was achieved when tested again in the absence of H2S (CH4/CO2/Ar:1/1/1). The 8Ni-3Cu-8Ce@SGA catalyst was deemed worthy of investigation for industrial applications.

Selective Synthesis of Vinyl Sulfides or 2-Methyl Benzothiazoles from Disulfides and CaC2 Mediated by a Trisulfur Radical Anion.

In this report, we have established a novel and efficient method for selectively synthesizing either vinyl sulfides or 2-methylbenzothiazoles from the reaction of CaC2 and disulfides. The selective synthesis of these two distinct products can be controlled by simply adjusting the amount of K2S. The underlying reaction mechanism has been thoroughly investigated through control experiments, HRMS, and FTIR, which collectively support the pivotal role of a trisulfur radical anion. This radical species, generated in situ from K2S, is essential for the homolytic cleavage of the S-S bonds in a catalytic manner. Additionally, the trisulfur radical anion also acts as an effective mediator for activating the vinyl group of 2-aminophenyl vinyl sulfides, facilitating the crucial intramolecular cyclization required to produce 2-methylbenzothiazoles. Moreover, CaC2 not only serves as an acetylene source but also creates the basic conditions essential for the selective formation of vinyl sulfides. This methodology demonstrates broad substrate compatibility and excellent functional group tolerance, significantly enhancing its practical utility in diverse synthetic applications.

The hyper-enrichment of silver through the aggregation of silver sulfide nanoparticles

Silver deposits have long been considered to form due to the direct precipitation of silver minerals from aqueous fluids, in which the metal is transported as chloride and/or bisulfide complexes. Ultra-high-grade silver ores have silver contents up to tens of weight-percent in the form of silver sulfides and native silver. Ore-forming fluids of most silver deposits, however, typically contain low silver contents of parts per million silver. The challenge is to explain how fluids with such low concentrations of silver can form ultra-high-grade silver ores. Here, we present direct mineralogical evidence from natural samples showing that the high-grade silver ores form from the aggregation of silver sulfide nanoparticles through intermediate microparticles and dendrites to acanthite crystals. Native silver grows from silver sulfides via solid-state silver ion aggregation. This study traces the formation of silver sulfides from their nanoparticulate precursors, thereby providing insights into the genesis of ultra-high-grade silver ores in a variety of metallogenic settings.

Palladium-catalyzed cycloisomerization of thiocarbamates with consecutive formation of quaternary carbon and sulfide

The Pd-catalyzed cycloisomerization of thiocarbamates with consecutive formation of a quaternary carbon and a sulfide is described. This Pd-catalyzed cascade reaction occurred with both alkylthiocarbamates and arylthiocarbamates, and arylthiocarbamates reacted faster than alkylthiocarbamates. The Pd-catalyzed cycloisomerization can be applied to phenylene- and alkylene-tethered substrates, and thiocarbamate was found to be less reactive than carbamimidothioate. The Pd-catalyzed cycloisomerization can be used to form bridged rings and is expected to be useful for ring construction of nitrogen-containing polycyclic natural products.

Augmented machine learning for sewage quality assessment with limited data

Physical, chemical, and biological processes within sewers significantly alter sewage composition during conveyance. This leads to the formation of sulfide and methane—compounds that contribute to sewer corrosion and greenhouse gas emissions. Reliable modeling of these compounds is essential for effective sewer management, but the development of machine learning (ML) models is hindered by differences in data accessibility and sampling frequencies of water quality variables. Here we present a mechanistically enhanced hybrid (ME-Hybrid) model that combines mechanistic modeling with data-driven approaches. This model harmonizes datasets with varying sampling frequencies and generates synthetic samples for ML training, thereby enhancing the monitoring of methane and sulfide in sewers. The optimal ME-Hybrid model integrates the backpropagation neural network with mechanistic frequency harmonization. We demonstrate that the ME-Hybrid model outperforms pure ML and linear interpolation in capturing fluctuating trends and extremes of sulfide concentrations, achieving a coefficient of determination (R2) of 0.94. Synthetic samples generated through mechanistic augmentation closely approximate real samples in modeling performance, statistical distribution, and data structure. This enables the model to maintain high predictive accuracy (R2 > 0.76) for sulfide even when trained on only 50 % of the dataset. Additionally, the ME-Hybrid model successfully assesses sewer methane concentrations with an R2 of 0.94, validating its applicability and generalization ability. Our results provide a reliable methodological framework for modeling and prediction under data scarcity. By facilitating better monitoring and management of sewer systems, the ME-Hybrid model aids in the development of strategies that minimize environmental impacts, enhance urban resilience, and ultimately lead to sustainable urban water systems.

Enhanced sulfide burial in low-oxygen aquatic environments could offset the carbon footprint of aquaculture production.

Carbon removal from the atmosphere is needed to keep global mean temperature increases below 2 °C. Here, we develop a model to explore how alkalinity production through enhanced iron sulfide formation in low-oxygen aquatic environments, such as aquaculture systems, could offer a cost-effective means of CO2 removal. We show that enhanced sulfide burial through the supply of reactive iron to surface sediments may be able to capture up to a hundred million tonnes of CO2 per year, particularly in countries with the highest number of fish farms, such as China and Indonesia. These efforts could largely offset the carbon footprint associated with their aquaculture industry. Enhanced sulfide burial could directly benefit both fish farms and surrounding ecosystems by removing toxic sulfide from aquatic systems, providing an addition to durable global CO2 removal markets and a path towards large-scale, carbon-neutral aquatic food production.

Change in the Chemical State of Phosphorus Sulfide Molecules Inside Single‐Walled Carbon Nanotubes

This article presents the first experiments on filling single‐walled carbon nanotubes (SWCNTs) with the phosphorus sulfides P4S3 and P4S10 using the ampoule method. Transmission electron microscopy examination reveals the encapsulation of phosphorus and sulfur species inside the cavities of SWCNTs without the formation of any regular structures. X‐ray photoelectron spectroscopy observes different oxidation states of P and S atoms, depending on the P/S ratio in the initial mixture used to fill the nanotubes. The Raman signals associated with the encapsulated species are low in intensity, and the vibrational modes are shifted and broadened as compared to those in crystalline P4S3 and P4S10. The proposed models for the arrangement of sulfur and phosphorus inside SWCNTs suggest the formation of 1D amorphous glassy phosphorus sulfides with stoichiometric ratios close to those of elemental phosphorus and sulfur in the initial mixtures.

The role of hydrogen gas in SRB-induced degradation of X80 pipeline steel in hydrogen-blending environments

The pipeline transportation of hydrogen poses higher challenges to the safety of pipes. In this study, the corrosion mechanisms of SRB in X80 pipeline steel under H₂ conditions were investigated. Thermodynamic analysis revealed that the introduction of hydrogen enhances SRB metabolic activity, facilitating the reduction of sulfate to sulfide and promoting hydrogen embrittlement. Additionally, hydrogen permeation tests confirmed that SRB significantly increase hydrogen diffusion in steel, accelerating corrosion. The enhanced hydrogen permeation under biotic conditions was linked to increased hydrogen uptake and sulfide formation, which further destabilized the steel microstructure. This study provides critical insights into the interplay between microbial activity, hydrogen permeation, and corrosion, offering a deeper understanding of the factors influencing hydrogen-assisted corrosion in steel pipelines. The findings contribute to the optimization of material performance and risk assessment in hydrogen-blended environments.

Diversified competitive sulfuration behaviors of concomitant heavy metal ions on copper recovery from copper smelting waste acid

Currently, sulfuration is widely used for the Cu(II) recovery from copper smelting waste acids (CSWA). However, the abundant concomitant heavy metal ions (HMIs) seriously obstruct Cu(II) recovery. In this paper, we find that the precipitation difficulty of HMI sulfide is determined by solubility product constant (Ksp), H+ concentration and S(−II) concentration, resulting in the diversified competitive sulfuration behaviors of concomitant HMIs on Cu(II) recovery. For concomitant HMIs without S(−II)-consuming ability, the positive-side competitive sulfuration behaviors on Cu(II) recovery are in the order of In(III) > Zn(II) > Ni(II) > Fe(II) > Mn(II). However, with the formation of concomitant HMIs sulfides, the negative-side competitive sulfuration behaviors on Cu(II) recovery are in the order of Fe(III) > As(III) > Bi(III) > Cd(II). According to the results of diffusion-growth-dissolution model, the S(−II)-combining process on HMIs surface is divided into S(−II)-capturing and S(−II)-consuming stages, related to Ksp value and HMIs precipitation, respectively. In actual CSWA, 5000 ∼ 15000 mg/L As(III) seriously inhibits the recovery efficiency of 500 ∼ 2000 mg/L Cu(II), and other concomitant HMIs (e.g., 250 ∼ 1200 mg/L Zn(II), 300 ∼ 450 mg/L Cd(II), 10 ∼ 200 mg/L Bi(III) and 20 ∼ 200 mg/L Fe(II)) will further affect Cu(II) recovery. Besides, ignoring these diversified competitive sulfurations of concomitant HMIs induces unreasonable S(−II) concentration for complete Cu(II) recovery, resulting in Cu(II) recovery issues: As(III) precipitation and Cu(II) residue. Thus, timely information in instantaneous Cu(II) concentration is a feasible strategy to accurately adjust S(−II) concentration via Cu(II) quantitative model. This work is devoted to the efficient and controllable recovery of Cu resources and the reduction of As-containing hazardous wastes in sulfuration treatment of actual CSWA.

Rapid Eutrophication of a Clearwater Lake: Trends and Potential Causes Inferred From Phosphorus Mass Balance Analyses.

Many clearwater lakes increasingly show symptoms of eutrophication, but the underlying causes are largely unknown. We combined long-term water chemistry data, multi-year sediment trap measurements, sediment analyses and simple mass balance models to elucidate potential causes of eutrophication of a deep temperate clearwater lake, where total phosphorus (TP) concentrations quadrupled within a decade, accompanied by expanding hypolimnetic anoxia. Discrepancies between modeled and empirically determined P inputs suggest that the observed sharp rise in TP was driven by internal processes. The magnitude of seasonal variation in TP greatly increased at the same time, both in surface and deep water, partly decoupled from deep water oxygen conditions. A positive correlation between annual P loss from the upper water column and hypolimnetic P accumulation could hint at a short-circuited P cycle involving lateral TP transport from shallow-water zones and deposition and release from sediments in deep water. This hypothesis is also supported by P budgets for the upper 20 m during stable summer stratification, suggesting that sediments in shallow lake areas acted as a P net source until 2018. These changes are potentially related to shifts in submerged macrophytes from wintergreen charophyte meadows (Nitellopsis obtusa) to annual free-floating hornwort (Ceratophyllum demersum) and to increased sulfide formation, promoting iron fixation in the sediments. Iron bound to sulfur is unavailable for binding P, resulting in a positive feedback between P release in shallow lake areas, primary productivity, macrophyte community structure and redox-dependent sediment biogeochemistry. Overall, our results suggest that relationships more complex than the commonly invoked increase in internal P release under increasingly anoxic conditions can drive rapid lake eutrophication. Since the proportion of littoral areas is typically large even in deep stratified lakes, littoral processes may contribute more frequently to the rapid lake eutrophication trends observed around the world than is currently recognized.

Effects of climate change and methane-rich fluid activity on sedimentary sulfur geochemical records in the northern South China Sea since mid-Pleistocene

Microbial sulfate reduction (MSR) and associated pyritic sulfide formation are important diagenetic processes in marine sediments. The sulfur isotopic composition of pyrite (δ34Spyr) is proven to be sensitive to changes in sedimentation rates and the content and reactivity of organic carbon, especially on the continental shelves and upper slopes (water depth < 350 m). However, the diagenetic responses of sulfur to variations in climatic and depositional conditions in the deep-sea sediments are still poorly understood. This study combines element contents and isotopes to characterize diagenetic interplays of sulfur, organic carbon, and methane in the continental slope sediments of the northern South China Sea since the mid-Pleistocene. Our data suggest that the total organic carbon (TOC) increased during glacial times, implying enhanced primary productivity due to increased nutrient supply by the East Asian Winter Monsoon, in addition to efficient transfer of organic carbon and better preservation of organic carbon due to reduced bottom water oxygen. Total sulfur and chromium reduction sulfur contents varied concomitantly with the TOC, suggesting an increased burial of organic carbon that enhanced the organoclastic sulfate reduction (OSR) and the formation of authigenic pyrite. The environmental changes did not induce a significant shift in δ34Spyr, due most likely to relatively low sedimentation rates and large fractionation in sulfur isotope through OSR during the glacial-interglacial cycles. Instead, it is hypothesized that the sulfate-driven anaerobic methane oxidation promoted the formation of a higher amount of authigenic pyrite. Consequently, it created a closed diagenetic system leading to positive excursions in δ34Spyr at the sulfate-methane transition zone. Our results suggest the vulnerability of pyrite formation and its sulfur isotopic composition to the changes in monsoon-driven primary productivity and the methane-rich fluid migrations in the continental margin sediments. This study complements the growing evidence for the local diagenetic controls on sedimentary sulfur geochemical records by highlighting the importance of early diagenesis in paleoenvironment reconstruction based on the content and sulfur isotopic composition of pyrite.

Substantial in situ Ti isotope variations in rutile record source and fluid evolution of porphyry copper mineralization systems

Titanium (Ti) and its stable isotopes have been widely used as tracers for magmatic processes. However, our understanding of Ti isotope behavior in magmatic-hydrothermal systems remains limited. Hence, the in situ Ti isotope composition (δ49Ti) of magmatic titanite and hydrothermal rutile associated with magnetite and chalcopyrite mineralization was determined for the first time in four well-characterized porphyry copper deposits in southern Tibet. The rutile formed through the alteration of primary Ti-rich minerals during fluid-rock interaction in the early high-temperature magnetite and later moderate-temperature chalcopyrite stages of mineralization. Hydrothermal rutile, altered from magmatic titanite, exhibits δ49Ti values similar to those of residual magmatic titanite. This suggests that hydrothermal rutile inherited the Ti isotope composition of magmatic titanite. The average δ49Ti values of rutile are negatively correlated with whole-rock εNd(t) and zircon εHf(t) data, and positively correlated with whole-rock (87Sr/86Sr)i values, which suggests that the initial Ti isotope compositions of hydrothermal rutile in porphyry copper deposits primarily reflect their source. Rutile from the Qulong deposit sometimes exhibits fractionation of δ49Ti at levels exceeding 0.5‰, displaying a negative correlation with Zr and FeO, which may be attributed to the formation of magnetite and rutile at an early potassic alteration stage. Isotopically light Ti is preferentially incorporated into magnetite and rutile. Thus, the rutile associated with sulfide mineralization that formed from the remaining fluids during a later stage of phyllic alteration is enriched in heavy δ49Ti. These findings contribute to the understanding of how rutile fractionates Ti isotopes in hydrothermal systems related to porphyry copper deposits. In local contexts, the substantial crystallization of magnetite, along with the preferential incorporation of isotopically light Ti during the early stages, leads to a decrease in oxygen fugacity within the ore-bearing fluid. This, in turn, facilitates the formation of sulfides during later stages. The results of this study demonstrate the efficacy of in situ Ti isotope analysis as a powerful tool for tracking fluid and metal sources, and can be used to help interpret ore precipitation throughout different stages of magmatic-to-hydrothermal ore-forming processes.

Biogeochemical sulfur transformations in the cohesive and permeable tidal flat sediments of Jade Bay (North Sea)

Intertidal flats are highly productive coastal marine ecosystems which are affected by fast changes in environmental conditions and host dynamic biogeochemical cycles in their sediments. Bioturbation by burrowing organisms and roots of plants strongly affects speciation and cycling of redox-sensitive elements in intertidal sediments. In this work, we have studied the impact of sediment type and vegetation on the cycling of redox-sensitive elements including sulfur, iron, and manganese in sandy and muddy tidal flats sediments in the Jade Bay (North Sea) and adjacent area. The redox speciation of these elements was analyzed in the pore-waters and the total sediment. The isotopic compositions of sulfur species were measured in non-vegetated sediments and in sediments which are inhabited by various plants. In the cohesive sediments, which are not affected by vegetation, a decrease in sulfate concentration, coupled with the presence of relatively high concentrations of hydrogen sulfide in the pore-waters and the presence of sulfide minerals as well the isotopic compositions of sulfur species are consistent with fast rates of sulfate reduction in the sediments. In the cohesive sediments affected by roots of Salicornia stricta and sediments desiccation, a cryptic sulfur cycle, which is characterized by microbial sulfate reduction coupled to fast reoxidation of hydrogen sulfide by Fe(III) (hydr)oxides and, possibly, by oxygen is present. Below the roots penetration depth, speciation of redox-sensitive elements is similar to those in the baren sediments. In the cohesive sediments affected by the roots of Spartina anglica and Triglochin maritima, which have longer roots, a cryptic sulfur cycle was detected in the upper 30 cm of sediments. At the sites that are characterized by permeable surface sediments and alternating permeable and cohesive layers in the deeper sediments, the composition of the sediment has a similar or even more significant impact on the speciation of the redox-sensitive elements than penetration of relatively weak roots of Spartina anglica. These sediments are characterized by the formation of hydrogen sulfide and sulfide oxidation intermediates in the cohesive layers and their diffusion to (and oxidation at) the boundaries between cohesive and permeable sediments. We conclude that in the cohesive sediments, the penetration of roots and desiccation leads to the formation of overall oxidized conditions, while in the sediments with alternating layers, permeability may provide a more significant control for speciation of redox-sensitive elements.

Structural Changes in Copper Slags During Slow Cooling

The objects of the study were converter slags from the Balkhash copper plant in their initial state and after heat treatment. Using mineralogical and X-ray phase analysis, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA), it was found that the initial converter slag and its thermally treated samples have identical matrices with almost complete coincidence in mineral and phase compositions. The distinguishing feature is the quantitative ratio of mineral components in the slag mass. Almost all of the iron is oxidized and present in the form of fayalite, magnetite, and magnetite, with other elements (silicon, copper, zinc, and aluminum) incorporated into its lattice. The structure of all slag samples indicates an association of sulfur exclusively with copper. Copper in the slags was identified in both metallic and sulfide forms. Slow cooling of the converter slag after its remelting contributes to the reduction in the sulfide–metal suspension in the volume of the melt and its coarsening. During slow cooling, structural changes occur not only in the main oxide part of the slag but also in the polymetallic globules.

Crystal Form-Dependent MnS for Diabetic Wound Healing: Performance and Mechanistic Insights.

In pharmaceuticals, the structural and functional alterations induced by biotransformation are well-documented. Many pharmaceuticals exist in various crystal forms, which govern their transformation and significantly impact their activity. However, in the field of inorganic nanomedicine, there is a paucity of research focusing on the influence of crystal form-dependent "metabolism" (transformation) on their activity and biomechanism. This study delves into the distinct performances of two crystal forms of manganese sulfide (MnS), namely α-MnS and γ-MnS, in bacteria-infected diabetic wound healing. In the initial stage of a wound, where the environment is neutral to slightly alkaline, MnS partially converts to MnxOy (comprising Mn2O3 and Mn3O4) and concurrently produces hydrogen sulfide (H2S); the conversion efficiency of γ-MnS significantly surpasses that of α-MnS. Additionally, γ-MnS is more soluble than α-MnS, which allows it to generate more Mn2+. These components collectively contribute to the superior bacteriostatic properties of MnS. In wound related cells, MnS stimulates the production of collagen I and vascular endothelial growth factor (VEGF), promote the M1 macrophages polarizing to the M2 phenotype, for extracellular matrix (ECM) remodeling. Notably, different transformation products have distinct functions. Consequently, the activity of MnS is dependent on its original crystal form related solubility and transformation efficiency.

Ice origins of OCS and chemistry of CS2-bearing ice mantles

ABSTRACT Understanding the formation of carbonyl sulfide (OCS) in interstellar ices is key to constrain the sulfur chemistry in the interstellar medium (ISM), since it is the only ice S-bearing molecule securely detected thus far. Two general pathways for OCS formation have been proposed: sulfurization of CO (CO + S) and oxidation of CS (CS + O), but their relative contribution in interstellar ices remains unconstrained. We have evaluated the contribution of both pathways to OCS formation upon energetic processing in isotopically labelled CO$_2$:CS$_2$ and CO:CS$_2$ ice samples at 7$-$50 K. Our results indicated that formation of OCS through the CS + O pathway was more favourable than through the CO + S pathway, as previously suggested by theoretical calculations. In addition, its relative contribution increased at higher temperatures. Therefore, this pathway could play a role in the ice formation of OCS, especially in warm regions where CO is expected to be preferentially in the gas phase. At the same time, we have explored the chemistry of CS$_2$-bearing, CO$_2$-, CO-, and also H$_2$O-rich ices, that could be relevant to the sulfur interstellar chemistry. We observed formation of a variety of S-bearing products in addition to OCS, including SO$_2$, C$_3$S$_2$, and S$_2$. However, a significant fraction of sulfur was not detected at the end of the experiments, and could be locked in long, undetectable sulfur allotropes, one of the potential carriers of the missing sulfur in the dense ISM.

Phenotypic and Genomic Characterization of a Sulfate-Reducing Bacterium Pseudodesulfovibrio methanolicus sp. nov. Isolated from a Petroleum Reservoir in Russia.

The search for the microorganisms responsible for sulfide formation and corrosion of steel equipment in the oil fields of Tatarstan (Russia) resulted in the isolation of a new halotolerant strictly anaerobic sulfate-reducing bacterium, strain 5S69T. The cells were motile curved Gram-negative rods. Optimal growth was observed in the presence of 2.0-4.0% (w/v) NaCl, at pH 6.5, and at 23-28 °C under sulfate-reducing conditions. The isolate was capable of chemoorganotrophic growth with sulfate and other sulfoxides as electron acceptors, resulting in sulfide formation; and of pyruvate fermentation resulting in formation of H2 and acetate. The strain utilized lactate, pyruvate, ethanol, methanol, fumarate, and fructose, as well as H2/CO2/acetate for sulfate reduction. The genome size of the type strain 5S69T was 4.16 Mb with a G + C content of 63.0 mol%. On the basis of unique physiological properties and results of the 16S rRNA gene-based phylogenetic analysis, phylogenomic analysis of the 120 conserved single copy proteins and genomic indexes (ANI, AAI, and dDDH), assigning the type strain 5S69T ((VKM B-3653T = KCTC 25499T) to a new species within the genus Pseudodesulfovibrio, is suggested, with the proposed name Pseudodesulfovibrio methanolicus sp. nov. Genome analysis of the new isolate showed several genes involved in sulfate reduction and its sulfide-producing potential in oil fields with high saline formation water.

Structural characteristics and biological evaluation of copper coating cotton material obtained by chemical reduction method

The article describes the preparation of new cotton materials obtained by chemical deposition of copper sulfide. This two-stage process consists of chelation of copper sulfate on cellulose chains of cotton (COT → COT-CuSO4) with subsequent precipitation of copper in the form of copper sulfide (COT-CuSO4 → COT-CuS) using sodium sulfide. The obtained COT-CuS composites were characterized physicobiologically. Thus, the structural characteristic of the Cotton-CuS material was determined by microscopy analysis (SEM), Atomic Absorption Spectrometry with Flame Excitation (FAAS), specific surface area and total pore volume analysis (BET). The copper functionalized cotton fabric was subjected to microbial activity tests against colonies of Gram-negative (Escherichia coli) and Gram-positive ( Staphylococcus aureus) bacteria and Chaetomium globosum, Aspergillus niger fungal molds species. Biochemical evaluation includes hematological tests of activated partial thromboplastin time (aPTT) and prothrombin time (PT). The substantial antimicrobial properties of the newly synthesized COT-CuS material with the lack of influence on blood coagulation processes offer prospects of a potential use as applications as an antibacterial/antifungal material.

Natural rhenium sulfide clusters formed under conditions of laser desorption-ionization.

Cluster forms of rhenium sulfides have important practical applications as catalysts in oil refining and thus present high interest. However, only a limited number of rhenium sulfide clusters have been described previously. It is known that cluster formation actively occurs under conditions of laser desorption-ionization; nevertheless, detailed studies of rhenium sulfides under such conditions were apparently not conducted previously. A sample of natural rhenium sulfide, collected from the fumarolic field of Kudriavy volcano (Iturup island, Russia) in 2002, was investigated using the laser desorption-ionization mass spectrometry method. The formed rhenium sulfide clusters were registered by a time-of-flight detector and identified programmatically using the software developed in IPCE RAS. The identification involved a comparison of the distribution of isotopic peak intensities, observed in the resulting mass spectra, with the theoretical probabilities of occurrence of various isotopologues for hypothetical rhenium sulfide species. Over 60 rhenium sulfide clusters of RexSy + and RexSyOz - types containing up to 10 rhenium atoms were formed when a sample of natural rhenium sulfide was exposed to laser desorption-ionization conditions. Several isolated heterometallic ReXMoSY + and ReXMoSYOZ - clusters containing up to eight rhenium atoms were additionally observed in the resulting mass spectra. The species with compositions, for which the electrically neutral analogs are known, apparently were the most stable rhenium sulfide clusters among the detected ones. The obtained data allowed summarizing the patterns of formation of rhenium sulfide clusters under conditions of laser desorption-ionization. The ability of rhenium and sulfur to form cluster species containing from 7 to 10 atoms of rhenium was likely discovered for the first time. The majority of the rhenium sulfide clusters described in this study, notably RexSy + ions containing over seven atoms of rhenium, were apparently not observed previously.