A Chemoproteomic Approach to Monitor Native Iron-Sulfur Cluster Binding.

Iron-sulfur (Fe-S) clusters are essential redox-active metallocofactors participating in electron transfer, radical chemistry, primary metabolism, and gene regulation. Successful trafficking and incorporation of Fe-S clusters into target proteins are critical to proper cellular function. While biophysical studies of isolated Fe-S proteins provide insight into the structure and function of these inorganic cofactors, few strategies currently exist to directly interrogate Fe-S cluster binding within a cellular environment. Here, we describe a chemoproteomic platform to report on Fe-S cluster incorporation and occupancy directly within a native proteome, enabling the characterization of Fe-S biogenesis pathways and the identification of undiscovered Fe-S proteins.

Gene-centered metagenome analysis of Vulcano Island soil (Aeolian archipelago, Italy) reveals diverse microbial key players in methane, hydrogen and sulfur cycles.

The Aeolian archipelago is known worldwide for its volcanic activity and hydrothermal emissions, of mainly carbon dioxide and hydrogen sulfide. Hydrogen, methane, and carbon monoxide are minor components of these emissions which together can feed large quantities of bacteria and archaea that do contribute to the removal of these notorious greenhouse gases. Here we analyzed the metagenome of samples taken from the Levante bay on Vulcano Island, Italy. Using a gene-centric approach, the hydrothermal vent community appeared to be dominated by Proteobacteria, and Sulfurimonas was the most abundant genus. Metabolic reconstructions highlight a prominent role of formaldehyde oxidation and the reverse TCA cycle in carbon fixation. [NiFe]-hydrogenases seemed to constitute the preferred strategy to oxidize H2, indicating that besides H2S, H2 could be an essential electron donor in this system. Moreover, the sulfur cycle analysis showed a high abundance and diversity of sulfate reduction genes underpinning the H2S production. This study covers the diversity and metabolic potential of the microbial soil community in Levante bay and adds to our understanding of the biogeochemistry of volcanic ecosystems.

A case of prolonged corneal sulfur foreign bodies and review of literature.

BACKGROUND: This case mainly describes a relatively rare case of an old mineral-like corneal foreign body that existed for up to 20 years, and did not significantly affect the visual quality of the patient. CASE PRESENTATION: A 56-year-old male miner complained of right eye vision loss for 3 years, swollen and painful for 4 months. Admission examination: Best corrected visual acuity was no light perception in the right eye and 20/20 in the left eye. Anterior segment examination: A large number of spot-like grayish-brown mineral foreign bodies in the conjunctiva of the nasal conjunctiva, emulsified silicone oil floating in the anterior chamber, Corneal foreign bodies in the right eye were widely distributed in the upper cortex and the proelastic layer. There were fewer foreign bodies in the left cornea. Previous medical history, 20 years ago due to forging and burning sulphur mine explosion, resulting in a large number of ore foreign bodies in the conjunctiva of both eyes. As these corneal foreign bodies did not affect the visual quality of the patient, we adopted a conservative treatment plan, did not remove these foreign bodies, and only carried out symptomatic treatment for the patient's secondary ocular hypertension. The patient was followed up normally in the outpatient department, and no cornea-related complications occurred up to now. CONCLUSIONS: First of all, it is necessary to understand the source and nature of the foreign body in patients with corneal and conjunctival foreign body injuries. In the second, for the old corneal metal foreign body, when the patient's visual acuity is stable and there are no symptoms of corneal irritation and inflammatory reaction, it can be Conservative treatment or outpatient follow-up observation. In the end, corneal Optical coherence tomography imaging should not be ignored, which is very important for determining the depth of embedding and the location of the corneal foreign body.

High-confidence placement of low-occupancy fragments into electron density using the anomalous signal of sulfur and halogen atoms.

Fragment-based drug design using X-ray crystallography is a powerful technique to enable the development of new lead compounds, or probe molecules, against biological targets. This study addresses the need to determine fragment binding orientations for low-occupancy fragments with incomplete electron density, an essential step before further development of the molecule. Halogen atoms play multiple roles in drug discovery due to their unique combination of electronegativity, steric effects and hydrophobic properties. Fragments incorporating halogen atoms serve as promising starting points in hit-to-lead development as they often establish halogen bonds with target proteins, potentially enhancing binding affinity and selectivity, as well as counteracting drug resistance. Here, the aim was to unambiguously identify the binding orientations of fragment hits for SARS-CoV-2 nonstructural protein 1 (nsp1) which contain a combination of sulfur and/or chlorine, bromine and iodine substituents. The binding orientations of carefully selected nsp1 analogue hits were focused on by employing their anomalous scattering combined with Pan-Dataset Density Analysis (PanDDA). Anomalous difference Fourier maps derived from the diffraction data collected at both standard and long-wavelength X-rays were compared. The discrepancies observed in the maps of iodine-containing fragments collected at different energies were attributed to site-specific radiation-damage stemming from the strong X-ray absorption of I atoms, which is likely to cause cleavage of the C-I bond. A reliable and effective data-collection strategy to unambiguously determine the binding orientations of low-occupancy fragments containing sulfur and/or halogen atoms while mitigating radiation damage is presented.

Unveiling the Nature and Strength of Selenium-Centered Chalcogen Bonds in Binary Complexes of SeO2 with Oxygen-/Sulfur-Containing Lewis Bases: Insights from Theoretical Calculations.

Among various non-covalent interactions, selenium-centered chalcogen bonds (SeChBs) have garnered considerable attention in recent years as a result of their important contributions to crystal engineering, organocatalysis, molecular recognition, materials science, and biological systems. Herein, we systematically investigated π-hole-type Se∙∙∙O/S ChBs in the binary complexes of SeO2 with a series of O-/S-containing Lewis bases by means of high-level ab initio computations. The results demonstrate that there exists an attractive interaction between the Se atom of SeO2 and the O/S atom of Lewis bases. The interaction energies computed at the MP2/aug-cc-pVTZ level range from -4.68 kcal/mol to -10.83 kcal/mol for the Se∙∙∙O chalcogen-bonded complexes and vary between -3.53 kcal/mol and -13.77 kcal/mol for the Se∙∙∙S chalcogen-bonded complexes. The Se∙∙∙O/S ChBs exhibit a relatively short binding distance in comparison to the sum of the van der Waals radii of two chalcogen atoms. The Se∙∙∙O/S ChBs in all of the studied complexes show significant strength and a closed-shell nature, with a partially covalent character in most cases. Furthermore, the strength of these Se∙∙∙O/S ChBs generally surpasses that of the C/O-H∙∙∙O hydrogen bonds within the same complex. It should be noted that additional C/O-H∙∙∙O interactions have a large effect on the geometric structures and strength of Se∙∙∙O/S ChBs. Two subunits are connected together mainly via the orbital interaction between the lone pair of O/S atoms in the Lewis bases and the BD*(OSe) anti-bonding orbital of SeO2, except for the SeO2∙∙∙HCSOH complex. The electrostatic component emerges as the largest attractive contributor for stabilizing the examined complexes, with significant contributions from induction and dispersion components as well.

Evaluation of functional characteristics of Acidithiobacillus thiooxidans microencapsulated in gum arabic by spray-drying as biotechnological tool in the mining industry.

The mining and metallurgical industry represents one of the leading causes of environmental pollution. In this context, the optimization of mineral waste management and the efficient extraction of metals of interest becomes an imperative priority for a sustainable future. Microorganisms such as Acidithiobacillus thiooxidans have represented a sustainable and economical alternative in recent years due to their capacity for environmental remediation in bioleaching processes because of their sulfur-oxidizing capacity and sulfuric acid generation. However, its use has been limited due to the reluctance of mine operators because of the constant reproduction of the bacterial culture in suitable media and the care that this entails. In this work, the central objective was to evaluate the functional characteristics of A. thiooxidans, microencapsulated and stored at room temperature for three years in vacuum bags, using a spray drying process with gum arabic as a wall vector. Growth kinetics showed a survival of 80 ± 0.52% after this long period of storage. Also, a qualitative fluorescence technique with a 5-cyano-2-3 ditolyl tetrazolium (CTC) marker was used to determine the respiratory activity of the microorganisms as soon as it was resuspended. On the other hand, the consumption of resuspended sulfur was evaluated to corroborate the correct metabolic functioning of the bacteria, with results of up to 50% sulfur reduction in 16 days and sulfate generation of 513.85 ± 0.4387 ppm and 524.15 ± 0.567 ppm for microencapsulated and non-microencapsulated cultures, respectively. These results demonstrate the success after three years of the microencapsulation process and give guidelines for its possible application in the mining-metallurgical industry.

Effects of acid mine drainage and sediment contamination on soil bacterial communities, interaction patterns, and functions in alkaline desert grassland.

Acid mine drainage and sediments (AMD-Sed) contamination pose serious ecological and environmental problems. This study investigated the geochemical parameters and bacterial communities in the sediment layer (A) and buried soil layer (B) of desert grassland contaminated with AMD-Sed and compared them to an uncontaminated control soil layer (CK). The results showed that soil pH was significantly lower and iron, sulfur, and electroconductivity levels were significantly higher in the B layer compared to CK. A and B were dominated by Proteobacteria and Actinobacteriota, while CK was dominated by Firmicutes and Bacteroidota. The pH, Fe, S, and potentially toxic elements (PTEs) gradients were key influences on bacterial community variability, with AMD contamination characterization factors (pH, Fe, and S) explaining 48.6 % of bacterial community variation. A bacterial co-occurrence network analysis showed that AMD-Sed contamination significantly affected topological properties, reduced network complexity and stability, and increased the vulnerability of desert grassland soil ecosystems. In addition, AMD-Sed contamination reduced C/N-cycle functioning in B, but increased S-cycle functioning. The results highlight the effects of AMD-Sed contamination on soil bacterial communities and ecological functions in desert grassland and provide a reference basis for the management and restoration of desert grassland ecosystems in their later stages.

Comprehensive profiles of sulfur cycling microbial communities along a mangrove sediment depth.

The sulfur (S) cycle is an important biogeochemical cycle with profound implications for both cellular- and ecosystem-level processes by diverse microorganisms. Mangrove sediments are a hotspot of biogeochemical cycling, especially for the S cycle with high concentrations of S compounds. Previous studies have mainly focused on some specific inorganic S cycling processes without paying specific attention to the overall S-cycling communities and processes as well as organic S metabolism. In this study, we comprehensively analyzed the distribution, ecological network and assembly mechanisms of S cycling microbial communities and their changes with sediment depths using metagenome sequencing data. The results showed that the abundance of gene families involved in sulfur oxidation, assimilatory sulfate reduction, and dimethylsulfoniopropionate (DMSP) cleavage and demethylation decreased with sediment depths, while those involved in S reduction and dimethyl sulfide (DMS) transformation showed an opposite trend. Specifically, glpE, responsible for converting S2O32- to SO32-, showed the highest abundance in the surface sediment and decreased with sediment depths; in contrast, high abundances of dmsA, responsible for converting dimethyl sulfoxide (DMSO) to DMS, were identified and increased with sediment depths. We identified Pseudomonas and Streptomyces as the main S-cycling microorganisms, while Thermococcus could play an import role in microbial network connections in the S-cycling microbial community. Our statistical analysis showed that both taxonomical and functional compositions were generally shaped by stochastic processes, while the functional composition of organic S metabolism showed a transition from stochastic to deterministic processes. This study provides a novel perspective of diversity distribution of S-cycling functions and taxa as well as their potential assembly mechanisms, which has important implications for maintaining mangrove ecosystem functions.

Phylogeny and Metabolic Potential of New Giant Sulfur Bacteria of the Family Beggiatoaceae from Coastal-Marine Sulfur Mats of the White Sea.

The family Beggiatoaceae is currently represented by 25 genera in the Genome Taxonomy Database, of which only 6 have a definite taxonomic status. Two metagenome-assembled genomes (MAGs), WS_Bin1 and WS_Bin3, were assembled from metagenomes of the sulfur mats coating laminaria remnants in the White Sea. Using the obtained MAGs, we first applied phylogenetic analysis based on whole-genome sequences to address the systematics of Beggiatoaceae, which clarify the taxonomy of this family. According to the average nucleotide identity (ANI) and average amino acid identity (AAI) values, MAG WS_Bin3 was assigned to a new genus and a new species in the family Beggiatoaceae, namely, 'Candidatus Albibeggiatoa psychrophila' gen. nov., sp. nov., thus providing the revised taxonomic status of the candidate genus 'BB20'. Analysis of 16S rRNA gene homology allowed us to identify MAG WS_Bin1 as the only currently described species of the genus 'Candidatus Parabeggiatoa', namely, 'Candidatus Parabeggiatoa communis', and consequently assign the candidate genus 'UBA10656', including four new species, to the genus 'Ca. Parabeggiatoa'. Using comparative whole-genome analysis of the members of the genera 'Candidatus Albibeggiatoa' and 'Ca. Parabeggiatoa', we expanded information on the central pathways of carbon, sulfur and nitrogen metabolism in the family Beggiatoaceae.

Nitrogen and sulfur for phosphorus: Lipidome adaptation of anaerobic sulfate-reducing bacteria in phosphorus-deprived conditions.

Understanding how microbial lipidomes adapt to environmental and nutrient stress is crucial for comprehending microbial survival and functionality. Certain anaerobic bacteria can synthesize glycerolipids with ether/ester bonds, yet the complexities of their lipidome remodeling under varying physicochemical and nutritional conditions remain largely unexplored. In this study, we thoroughly examined the lipidome adaptations of Desulfatibacillum alkenivorans strain PF2803T, a mesophilic anaerobic sulfate-reducing bacterium known for its high proportions of alkylglycerol ether lipids in its membrane, under various cultivation conditions including temperature, pH, salinity, and ammonium and phosphorous concentrations. Employing an extensive analytical and computational lipidomic methodology, we identified an assemblage of nearly 400 distinct lipids, including a range of glycerol ether/ester lipids with various polar head groups. Information theory-based analysis revealed that temperature fluctuations and phosphate scarcity profoundly influenced the lipidome's composition, leading to an enhanced diversity and specificity of novel lipids. Notably, phosphorous limitation led to the biosynthesis of novel glucuronosylglycerols and sulfur-containing aminolipids, termed butyramide cysteine glycerols, featuring various ether/ester bonds. This suggests a novel adaptive strategy for anaerobic heterotrophs to thrive under phosphorus-depleted conditions, characterized by a diverse array of nitrogen- and sulfur-containing polar head groups, moving beyond a reliance on conventional nonphospholipid types.

A novel coupling process to replace the traditional multi-stage anammox process-sulfur autotrophic denitrification coupled anammox system.

A novel coupling process to replace the traditional multi-stage anammox process-sulfur autotrophic denitrification (SAD) coupled anaerobic ammonium oxidation (anammox) system was designed, which solved problems of nitrate produced in anammox process and low nitrate conversion rate caused by nitrite accumulation in SAD process. Different filter structures (SAD filter and anammox granular sludge) were investigated to further explore the excellent performance of the novel integrated reactor. The results of sequential batch experiments indicated that nitrite accumulation occurred during SAD, which inhibited the conversion of nitrate to dinitrogen gas. When SAD filter and anammox granular sludge were added to packed bed reactor simultaneously, the nitrate removal rate increased by 37.21% and effluent nitrite concentration decreased by 100% compared to that achieved using SAD. The stratified filter structure solved groove flow. Different proportion influence of SAD filter and anammox granular sludge on the stratified filter structure was evaluated. More suitable ratio of SAD filter to anammox granular sludge was 2:1. Proteobacteria (57.26%), Bacteroidetes (20.12%) and Chloroflexi (9.95%) were the main phyla. The dominant genera of denitrification functional bacteria were Thiobacillus (39.80%), Chlorobaculum (3.99%), norank_f_PHOs-HE36 (2.90%) and Ignavibacterium (2.64%). The dominant genus of anammox bacterium was Candidatus_Kuenenia (3.05%).

Sulfur/zinc co-doped biochar for stabilization remediation of mercury-contaminated soil: Performance, mechanism and ecological risk.

In this study, a novel sulfur/zinc co-doped biochar (SZ-BC) stabilizer was successfully developed for the remediation of mercury-contaminated soil. Results from SEM, TEM, FTIR and XRD revealed that biochar (BC) was successfully modified by sulfur and zinc. In the batch adsorption experiments, the sulfur-zinc co-pyrolysis biochar displayed excellent Hg(II) adsorption performance, with the maximum adsorption capacity of SZ-BC (261.074 mg/g) being approximately 16.5 times that of BC (15.855 mg/g). Laboratory-scale static incubation, column leaching, and plant pot experiments were conducted using biochar-based materials. At an additional dosage of 5 % mass ratio, the SZ-BC exhibits the most effective stabilization of mercury in soil, leading to a significant reduction in leaching loss compared to the control group (CK) by 51.30 %. Following 4 weeks of incubation and 2 weeks of leaching with SZ-BC, the residual mercury in the soil increased by 27.84 %. As a result, potential ecological risk index of mercury decreased by 92 % compared to the CK group. In the pot experiment, SZ-BC significantly enhanced the growth of Chinese cabbage, with biomass and root dry weight reaching 3.20 and 2.80 times that of the CK group, respectively. Additionally, the Translocation Factor (TF) and Bioconcentration Factor (BF) were reduced by 44.86 % and 74.43 %, respectively, in the SZ-BC group compared to the CK group. Moreover, SZ-BC can effectively improve enzyme activities and increase microbial communities in mercury-contaminated soils. The mechanisms of adsorption and stabilization were elucidated through electrostatic adsorption, ion exchange, surface complexation, and precipitation. These findings provide a potentially effective material for stabilizing soils contaminated with mercury.

Scaffold-Hopping Strategies in Aurone Optimization: A Comprehensive Review of Synthetic Procedures and Biological Activities of Nitrogen and Sulfur Analogues.

Aurones, particular polyphenolic compounds belonging to the class of minor flavonoids and overlooked for a long time, have gained significative attention in medicinal chemistry in recent years. Indeed, considering their unique and outstanding biological properties, they stand out as an intriguing reservoir of new potential lead compounds in the drug discovery context. Nevertheless, several physicochemical, pharmacokinetic, and pharmacodynamic (P3) issues hinder their progression in more advanced phases of the drug discovery pipeline, making lead optimization campaigns necessary. In this context, scaffold hopping has proven to be a valuable approach in the optimization of natural products. This review provides a comprehensive and updated picture of the scaffold-hopping approaches directed at the optimization of natural and synthetic aurones. In the literature analysis, a particular focus is given to nitrogen and sulfur analogues. For each class presented, general synthetic procedures are summarized, highlighting the key advantages and potential issues. Furthermore, the biological activities of the most representative scaffold-hopped compounds are presented, emphasizing the improvements achieved and the potential for further optimization compared to the aurone class.

Current understanding of enzyme structure and function in bacterial two-component flavin-dependent desulfonases: Cleaving C-S bonds of organosulfur compounds.

The inherent structural properties of enzymes are critical in defining catalytic function. Often, studies to evaluate the relationship between structure and function are limited to only one defined structural element. The two-component flavin-dependent desulfonase family of enzymes involved in bacterial sulfur acquisition utilize a comprehensive range of structural features to carry out the desulfonation of organosulfur compounds. These metabolically essential two-component FMN-dependent desulfonase systems have been proposed to utilize oligomeric changes, protein-protein interactions for flavin transfer, and common mechanistic steps for carbon-sulfur bond cleavage. This review is focused on our current functional and structural understanding of two-component FMN-dependent desulfonase systems from multiple bacterial sources. Mechanistic and structural comparisons from recent independent studies provide fresh insights into the overall functional properties of these systems and note areas in need of further investigation. The review acknowledges current studies focused on evaluating the structural properties of these enzymes in relationship to their distinct catalytic function. The role of these enzymes in maintaining adequate sulfur levels, coupled with the conserved nature of these enzymes in diverse bacteria, underscore the importance in understanding the functional and structural nuances of these systems.

Mechanical and thermoelectric properties of ZrX2 and HfX2 (X = S and Se) from Van der Waals density-functional theory.

The structural, mechanical, and thermoelectric characteristics of layered transition metal dichalcogenides MX2 (M = Zr, Hf; X = S, Se) have been studied using density functional theory along with van der Waals correction. The exchange-correlation functional, enhanced with corrections for van der Waals interactions, has been evaluated for the hexagonal bulk structures of these materials. The analysis of elastic properties reveals that these compounds exhibit brittleness at zero pressure and conform to Born's criteria for mechanical stability. Examination of elastic constants and moduli suggests that the compounds possess reasonable machinability, moderate hardness, and anisotropy in terms of sound velocity. Transport properties, including the Seebeck coefficient, electrical conductivity, thermal conductivity, and power factor, have been computed using the semi-classical Boltzmann theory implemented in the BoltzTraP code. All investigated compounds exhibit excellent thermoelectric performance at high temperatures. This result suggests that our compounds are highly promising candidate for practical utilization in the thermoelectric scope.

Synergistic Enhancement of CO2 photoreduction through sulfur defects in (3D/2D) CdS-nanoflowers/CN Binary heterojunction photocatalyst under visible light.

Global warming is the biggest threat to the entire world owing to the continuous release of greenhouse gases such as CO2 from various sources. Herein, we have utilized renewable energy for the conversion of CO2 to valuable feedstocks through a semiconductor-mediated photocatalytic system. The cadmium sulfide nanoflowers (CS-NFs) decorated graphitic carbon nitride (CN) through a solvothermal route to form a Z-scheme CSCN heterojunction. The as-synthesized material has been characterized by various spectroscopic and microscopic tools. The optimal CSCN-0.5 (1:0.5) photocatalyst achieves a CO production rate of 130.9 µmol g-1 under visible light irradiation of 4h (λ > 420 nm), doubling that of pristine CS-NFs and CN. CO, along with CH4 (3.4 µmol g-1) and C2H6 (2.9 µmol g-1), is the sole product detected. Experimental results indicate that the CSCN-0.5 photocatalyst spatially separates electron-hole pairs, suppresses charge carrier recombination, and maintains robust redox ability, enhancing CO2 photoreduction. The CO2 reduction mechanism over CSCN heterojunction was also studied through in-situ DRIFTS and electron spin resonance (ESR) measurements. Therefore, CSCN proves that it could be used as a robust photocatalyst for the CO2 reduction reactions towards C1 and C2 feedstocks.

Detection of sulphur(II) of carbon dots synthesized from Gardenia residue.

The detection of anions using carbon dots (CDs) has received less attention compared to cations. Therefore, the present study aimed to develop a fluorescence sensor based on carbon dots (CDs) capable of detecting S2- in real water samples. The CDs were successfully prepared from the residues of a traditional Chinese herb, Gardenia, which emitted green photoluminescence (PL) under ultraviolet light irradiation. The as-prepared CDs were quasi-spherical in shape and ranged in size from 10 to 30 nm. Different detailed analyses proved that the CDs had good morphology, various functional groups, high water solubility, great optical features, and excellent stability under diverse environmental conditions. The ion detection showed that only Ag+ had the strongest fluorescence quenching effect on the CDs, however, the addition of S2- could recover their fluorescence. Based on these results, an "off-on" fluorescence sensor was achieved to selectively detect the concentration of S2- in real water samples with a limit of detection (LOD) of 39 µM, which further expanded the application of residues from traditional Chinese herbal medicine.

Highly catalytic sulfur-doped and bimetal-coordinated CoFe(CN)5NO nanoparticles coupled with PER/HCR amplification cascades for sensitive electrochemical aptamer luteinizing hormone assay.

Sensitive monitoring of luteinizing hormone (LH), a glycoprotein that regulates the synthesis of regulatory steroid hormones, can facilitate the diagnosis of various reproductive diseases. In this work, a new and highly catalytic Sulfur-doped and bimetal-coordinated CoFe(CN)5NO (denoted as S-CoFe(CN)5NO) nanoparticles are synthesized. Such material is further used to construct high performance sensing interface and coupled with primer exchange reaction (PER) and hybridization chain reaction (HCR) amplification cascades for sensitive electrochemical aptamer-based LH assay. Target LH molecules bind aptamer sequences in DNA duplex probes to liberate ssDNA strands, which initiate subsequent PER/HCR amplification cascades for the capture of many ferrocene (Fc)-tagged DNAs on sensing interface. S-CoFe(CN)5NO subsequently leads to catalytic oxidation of these Fc tags for yielding substantially magnified currents for realizing ultrasensitive assay of LH with the detection limit of 0.69 pM in range from 5 pM to 10 nM. Owing to the high specificity of aptamer, such sensor has high selectivity and can achieve low levels of LH assay in diluted serum samples. With the successful demonstration for detecting trace LH, such sensor can be easily extended as a universal aptamer-based electrochemical sensing method for monitoring various target analytes in the biomedical and biological fields.

Fabrication of N and S co-doped lignin-based porous carbon aerogels loaded with FeCo alloys and their application to oxygen evolution and reduction reactions in Zn-air batteries.

Zn-air batteries are a highly promising clean energy sustainable conversion technology, and the design of dual-function electrocatalysts with excellent activity and stability is crucial for their development. In this work, FeCo alloy loaded biomass-based N and S co-doped carbon aerogels (FeCo@NS-LCA) were fabricated from chitosan and lignosulfonate-metal chelates via liquid nitrogen pre-frozen synergistic high-temperature carbonization with application in electrocatalytic reactions. The abundant oxygen-containing functional groups on lignosulfonates have a chelating effect on metal ions, which can avoid the aggregation of metal nanoparticles during carbonation and catalysis, facilitating the construction of a nanoconfinement catalytic system with biomass carbon as the domain-limiting body and FeCo nanoparticles as the active sites. FeCo@NS-LCA exhibited catalytic activity (E1/2 = 0.87 V, JL = 5.7 mA cm-2) comparable to the commercial Pt/C in the oxygen reduction reaction (ORR), excellent resistance to methanol toxicity and stability. Meanwhile, the overpotential of oxygen evolution reaction (OER) was 324 mV, close to that of commercial RuO2 catalysts (351 mV). This study utilizes the coordination action of lignosulfonate to provide a novel and environmentally friendly method for the preparation of confined nano-catalysts and provides a new perspective for the high-value utilization of biomass resources.

Insight into the photodynamic mechanism and protein binding of a nitrosyl iron-sulfur [Fe2S2(NO)4]2- cluster.

Iron-sulfur cluster conversion and nitrosyl modification are involved in regulating their functions and play critical roles in signaling for biological systems. Hereby, the photo-induced dynamic process of (Me4N)2[Fe2S2(NO)4] was monitored using time-resolved electron paramagnetic resonance (EPR) spectra, MS spectra and cellular imaging methods. Photo-irradiation and the solvent affect the reaction rates and products. Spectroscopic and kinetic studies have shown that the process involves at least three intermediates: spin-trapped NO free radical species with a gav at 2.040, and two other iron nitrosyl species, dinitrosyl iron units (DNICs) and mononitrosyl iron units (MNICs) with gav values at 2.031 and 2.024, respectively. Moreover, the [Fe2S2(NO)4]2- cluster could bind with ferritin and decompose gradually, and a binding state of dinitrosyl iron coordinated with Cys102 of the recombinant human heavy chain ferritin (rHuHF) was finally formed. This study provides insight into the photodynamic mechanism of nitrosyl iron - sulfur clusters to improve the understanding of physiological activity.