Oxidation Of Sulfides Research Articles

Catalytic Enantioselective Sulfoxidation of Functionalized Thioethers Mediated by Aspartic Acid-Containing Peptides.

A peptide-catalyzed enantioselective oxidation of sulfides to yield pharmaceutically relevant chiral sulfoxides is reported. Experimental evidence suggesting that a hydrogen bond-donating moiety must be present in the substrate to achieve high levels of enantioinduction is supported by computational modeling of transition states. These models also indicate that dual points of contact between the peptidic catalyst and substrate are likely responsible for the formation of one desired sulfoxide in 94:6 er.

Isotope hydrology of the intermontane Elk Valley, British Columbia: an assessment of water resources around coal mining operations

ABSTRACT This study aimed to synthesise and interpret stable isotopic data (δ 2H and δ 18O) from various sources to understand the isotope hydrology around coal mine operations in Elk Valley, B.C., Canada. The data, including precipitation, groundwaters, seeps, and mine rock drains, were used to construct a local meteoric water line (LMWL) for the Elk Valley, evaluate the spatiotemporal isotopic composition of its groundwater, and assess mine seepage and mine rock drain discharge. The study revealed a robust LMWL relation (δ 2H = 7.4 ± 0.2 · δ 18O – 4.3 ± 4.1). The groundwater and seep data indicated a winter season bias and a north–south latitudinal gradient, suggesting rapid near-surface groundwater flow without significant post-precipitation evaporation. Porewater isotope samples from unsaturated mine rock piles (MRPs) showed site-specific evaporation patterns, potentially due to convective air flows or exothermic sulphide oxidation. This research revealed the influence of groundwater and meltwater on rock drain discharge. Based on evaporative mass balance calculations, MRPs seasonally contributed ca. 5 %(December base flow) and 22 % (snowmelt) to drain discharge. The findings underscore the value of stable isotope data collections in the Elk Valley to help better define and quantify the hydrology–hydrogeology, including a better understanding of evaporative conditions in MRPs.

Photocatalytic oxidation of benzylamines and sulfides using selected organoboron complexes as molecular oxygen activators

In this work a synthetic protocol was developed to obtain a series of diarylborinic complexes bearing a diarylboron moiety chelated with various bidentate N,O-ligands derived from 5-chloro-8-hydroxy-7-iodoquinoline, quinoline-2,4-dicarboxylic acid or 2-(2-hydroxy-5-methylphenyl)benzotriazole. The obtained complexes were characterized by NMR, IR, CV, UV–vis and single-crystal X–ray diffraction analyses. The experimental data were supported by theoretical calculations. The obtained complexes were tested as singlet oxygen sensitizers for the oxidation of 2-furancarboxylic acid, oxidative coupling of benzylamines and oxidation of sulfides. Among the studied compounds, the diarylborinic derivative bearing a 5-chloro-8-oxy-7-iodoquinolinate ligand was selected as the most economic singlet oxygen sensitizer. However, the diphenylborinic complex bearing an 8-oxyquinolinate ligand was the most efficient for the selective oxidation of various benzylamines to their respective N-benzylidene benzylamines.

Reactive adsorption and catalytic oxidation of gaseous hydrogen sulfide using a prototype air purifier built with bismuth-doped titanium dioxide

A prototype air purifier (AP) module has been constructed using bismuth-doped titanium dioxide (Bix-P25: x(%) as Bi/Ti molar ratios of 1.1, 2.1, 3.3, 5.3, and 8.7). The reactive adsorption property of Bix-P25 materials is evaluated against H2S gas at a recirculation rate of 160 L min−1 in a 17 L closed chamber. The AP (Bi5.3-P25) exhibits superior performance against 10 ppm H2S in dry air under dark conditions (i.e., without light irradiation), with a removal efficiency (XH2S)= 99% in 5 mins, reaction kinetic rate (r (at X = 10%))= 7.3 mmol h−1g−1, and partition coefficient= 0.18 mol kg−1 Pa−1. As such, its superiority is evident over the reference AP (P25) filter with XH2S < 10%. The clean air delivery rate (CADR) of AP (Bi5.3-P25) increases noticeably from 9.9 to 17.8 L min−1 with increasing relative humidity (RH) from 0 to 80%, respectively. In contrast, the CADR decreases from 9.9 to 5.8 L min−1 as the H2S increases from 10 to 20 ppm. According to density functional theory (DFT), the presence of H2O vapor enhances the hydroxylation of Bix-P25 surface to promote H2S mineralization through the formation of TiS3 (i.e., thermodynamic reaction of S atom with the catalytic surface). Complete removal of H2S on the Bi5.3-P25 surface is also confirmed consistently through gas chromatography-mass spectrometry (GC-MS), in-situ diffuse reflection infrared spectroscopy (in-situ DRIFTS), and elemental analysis (EA). This work represents the first utilization of Bix-P25 materials fabricated on an AP platform toward the desulfurization of H2S at room temperature (RT). The practical utility of Bix-P25 is overall validated by its eminent role in reactive adsorption and catalytic oxidation (RACO) of H2S from the air.

Remediation of AMD based on hydrogeochemical zonation: A typical metal mine in China

Mining activities disrupt the natural oxidative balance underground, increasing the oxidation of metal sulfides like pyrite. This process leads to the formation of highly acidic mine drainage (AMD) with elevated concentrations of iron (Fe) and sulfate (SO42−). However, generic plugging and backfilling methods, when applied without considering the specific post-mining oxidative environments of different metal mines, often yields minimal results. To clarify the distribution of the underground redox environment after mining of a metal mine in Dexing, China, fifteen water samples from flood and dry periods, as well as fifteen borehole samples, were collected for hydrogeological and chemical analysis. For the first time, the study proposed that the redox zone could be identified and delineated through vertical analysis of water storage media, mineral composition, and hydrochemical characteristics. A hydrogeochemical cause model was constructed, revealing that AMD formation primarily occurs in oxidative and transition zones. Based on the redox zone characteristics of the study area, actual engineering sealing was performed on the oxidation and transition zones of cavity No. 23. As a result, the pH increased from 2.5 before remediation to 4.5, indicating a reduction in acidity. The concentrations of SO42− and Fe significantly decreased, reducing from 1360.0 mg/L and 147.0 mg/L before treatment to 726.0 mg/L and 23.6 mg/L after treatment; the total decrease amounting to 46.6 % and 84.0 %, respectively. The concentrations of Mn and Cu similarly, decreased by 10.7 % and 15.6 %, respectively. This study provides a novel approach and valuable reference for the refined identification and classification of redox zones after metal mine exploitation, as well as for the targeted plugging and treatment of cavities that produce AMD.

Chondroitin Sulfate Ameliorates Hypertension in Male Offspring Rat Born to Mothers Fed an Adenine Diet.

Pregnant women with chronic kidney disease (CKD) face increased risks of adverse outcomes in their adult offspring. Offspring rats born to dams fed an adenine diet develop hypertension, coinciding with dysregulated hydrogen sulfide (H2S) and nitric oxide (NO) pathways, as well as alterations in gut microbiota. Chondroitin sulfate (CS) is a multifunctional food known for its diverse bioactivities. As a sulfate prebiotic, CS has shown therapeutic potential in various diseases. Here, we investigated the protective effects of maternal CS supplementation against hypertension in offspring induced by an adenine diet. Mother rats were administered regular chow, 0.5% adenine, 3% CS, or a combination throughout gestation and lactation. Maternal CS supplementation effectively protected offspring from hypertension induced by the adenine diet. These beneficial effects of CS were connected with increased renal mRNA and protein levels of 3-mercaptopyruvate sulfurtransferase, an enzyme involved in H2S production. Furthermore, maternal CS treatment significantly enhanced alpha diversity and altered beta diversity of gut microbiota in adult offspring. Specifically, perinatal CS treatment promoted the abundance of beneficial microbes such as Roseburia hominis and Ruminococcus gauvreauii. In conclusion, perinatal CS treatment mitigates offspring hypertension associated with maternal adenine diet, suggesting that early administration of sulfate prebiotics may hold preventive potential. These findings warrant further translational research to explore their clinical implications.

Synergistic effect of Ca(NO3)2 - CaO2 on the improvement of sediment microecology: Transformation of sulfur and ferrous iron, and improvement mechanism

The synergy of Ca(NO3)2 and CaO2 can effectively reduce the risks of secondary pollution caused by nitrate escape and release. However, the timing and suitable dosage of Ca(NO3)2 and CaO2 during the synergistic interaction have not been fully investigated. In this work, we separated acid volatile sulfides (AVS) oxidation and ferrous iron oxidation by controlling the dosage of Ca(NO3)2. Results indicated that at a low RN/1.6S2−ratio, there was an obvious competitive relationship between AVS oxidation and ferrous iron oxidation, and sulfide was oxidized prior to ferrous iron. More efficient AVS and ferrous iron oxidation was achieved using Ca(NO3)2 to oxidize AVS and CaO2 to oxidize ferrous iron. After the treatment with Ca(NO3)2 and CaO2, the anaerobic reduction environment of the sediment was modified, and the metabolic pathways dominated by sulfate respiration and methanogenic metabolism in the sediment were gradually converted to nitrate-reduction and dissimilatory iron reduction. The synergy of Ca(NO3)2 and CaO2 could reduce 99.61 % CH4 compared with control check and could reduce 81.66 % N2O compared with adding Ca(NO3)2 only. Furthermore, the biodegradability of organic matter was improved due to the transformation of stubborn organic matter. These results provide valuable guidance for applying Ca(NO3)2 and CaO2 in sediment remediation.

Regulation of arsenate stress by nitric oxide and hydrogen sulfide in Oryza sativa seedlings: Implication of sulfur assimilation, glutathione biosynthesis, and the ascorbate-glutathione cycle and its genes

Seed priming by nitric oxide (NO) and hydrogen sulphide (H2S) in combating against abiotic stress in plants is well documented. However, knowledge of fundamental mechanisms of their crosstalk is scrambled. Therefore, the reported study examined the probable role of NO and H2S in the mitigation of arsenate toxicity (As(V)) in rice seedlings and whether their potential signalling routes crossover. Results report that As(V) toxicity limited shoot and root length growth with more As accumulation in roots. As(V) further caused elevated reactive oxygen species levels, inhibited ascorbate-glutathione cycle enzymes and relative gene expression of its enzymes and thus, causing lipid and protein oxidation. These results correlate with reduced nitric oxide synthase-like and L–cysteine desulfhydrase activity along with endogenous NO and H2S. While, L-NAME or PAG augmented As(V) toxicity, and addition of SNP or NaHS effectively reversed their respective effects. Furthermore, SNP under PAG or NaHS under L-NAME were able to pacify As(V) stress, implicating that endogenous NO and H2S efficiently ameliorate As(V) toxicity but without their shared signaling in rice seedlings.

Electrolyte and interfacial engineering for self-formation of In₂S₃/In₂O₃ heterojunction with an enhanced photoelectrochemical activity

Electrolyte and interfacial engineering of photoanodes has become a crucial approach to enhance photoelectrochemical water-splitting performance. By optimizing both the electrolyte and the interfacial properties of the photoanode, the synergistic effects of the heterojunction and electrolyte can be leveraged to improve efficiency. In this work, we explore the crucial role of electrolyte and interfacial engineering in optimizing photoanode performance. By engineering an In2O3 film in a polysulfide electrolyte to form an in-situ In₂S₃/In₂O₃ heterojunction interface, we demonstrate a significant increase in anodic photocurrent compared to traditional aqueous Na2SO4 or NaOH electrolytes. This enhancement is attributed to both the thermodynamically favorable oxidation of sulfide and sulfite, and the unique electronic structure developed at the In₂S₃/In₂O₃ junction, which significantly improves charge separation and overall performance. Based on this finding, an efficient In₂S₃/In₂O3 heterojunction interface through optimal anion exchange with sulfur was developed, leading to a maximum photocurrent density of 5.57 mA cm−2 in the polysulfide electrolyte. In addition, detailed structural, optical, and photoelectrochemical properties of the In₂S₃/In₂O₃ interface providing insights into the mechanisms underlying the enhanced water-splitting performance have also been discussed.

Structural and biochemical characterization of an encapsulin-associated rhodanese from Acinetobacter baumannii.

Rhodanese-like domains (RLDs) represent a widespread protein family canonically involved in sulfur transfer reactions between diverse donor and acceptor molecules. RLDs mediate these transsulfuration reactions via a transient persulfide intermediate, created by modifying a conserved cysteine residue in their active sites. RLDs are involved in various aspects of sulfur metabolism, including sulfide oxidation in mitochondria, iron-sulfur cluster biogenesis, and thio-cofactor biosynthesis. However, due to the inherent complexity of sulfur metabolism caused by the intrinsically high nucleophilicity and redox sensitivity of thiol-containing compounds, the physiological functions of many RLDs remain to be explored. Here, we focus on a single domain Acinetobacter baumannii RLD (Ab-RLD) associated with a desulfurase encapsulin which is able to store substantial amounts of sulfur inside its protein shell. We determine the 1.6 Å x-ray crystal structure of Ab-RLD, highlighting a homodimeric structure with a number of unusual features. We show through kinetic analysis that Ab-RLD exhibits thiosulfate sulfurtransferase activity with both cyanide and glutathione acceptors. Using native mass spectrometry and in vitro assays, we provide evidence that Ab-RLD can stably carry a persulfide and thiosulfate modification and may employ a ternary catalytic mechanism. Our results will inform future studies aimed at investigating the functional link between Ab-RLD and the desulfurase encapsulin.

Metagenomics and Stable Isotopes Uncover the Augmented Sulfide-Driven Autotrophic Denitrification in a Seasonally Hypoxic, Sulfate-Abundant Reservoir.

The mechanism governing sulfur cycling in nitrate reduction within sulfate-rich reservoirs during seasonal hypoxic conditions remains poorly understood. This study employs nitrogen and oxygen isotope fractionation in nitrate, along with metagenomic sequencing to elucidate the intricacies of the coupled sulfur oxidation and nitrate reduction process in the water column. In the Aha reservoir, a typical seasonally stratified water body, we observed the coexistence of denitrification, bacterial sulfide oxidation, and bacterial sulfate reduction in hypoxic conditions. This is substantiated by the presence of abundant N/S-related genes (nosZ and aprAB/dsrAB) and fluctuations in N/S species. The lower 15εNO3/18εNO3 ratio (0.60) observed in this study, compared to heterotrophic denitrification, strongly supports the occurrence of sulfur-driven denitrification. Furthermore, we found a robust positive correlation between the metabolic potential of bacterial sulfide oxidation and denitrification (p < 0.05), emphasizing the role of sulfide produced via sulfate reduction in enhancing denitrification. Sulfide-driven denitrification relied on ∑S2- as the primary electron donor preferentially oxidized by denitrification. The pivotal genus, Sulfuritalea, emerged as a central player in both denitrification and sulfide oxidation processes in hypoxic water bodies. Our study provides compelling evidence that sulfides assume a critical role in regulating denitrification in hypoxic water within an ecosystem where their contribution to the overall nitrogen cycle was previously underestimated.

The potential linkage between sediment oxygen demand and microbes and its contribution to the dissolved oxygen depletion in the Gan River.

The role of sediment oxygen demand (SOD) in causing dissolved oxygen (DO) depletion is widely acknowledged, with previous studies mainly focusing on chemical and biological SOD separately. However, the relationship between the putative functions of sediment microbes and SOD, and their impact on DO depletion in overlying water, remains unclear. In this study, DO depletion was observed in the downstream of the Gan River during the summer. Sediments were sampled from three downstream sites (YZ, Down1, and Down2) and one upstream site (CK) as a control. Aquatic physicochemical parameters and SOD levels were measured, and microbial functions were inferred from taxonomic genes through analyses of the 16S rRNA gene. The results showed that DO depletion sites exhibited a higher SOD rate compared to CK. The microbial community structure was influenced by the spatial variation of Proteobacteria, Chloroflexi, and Bacteroidota, with total organic carbon (TOC) content acting as a significant environmental driver. A negative correlation was observed between microbial diversity and DO concentration (p < 0.05). Aerobic microbes were more abundant in DO depletion sites, particularly Proteobacteria. Microbes involved in various biogeochemical cycles, such as carbon (methane oxidation, methanotrophs, and methylotrophs), nitrogen (nitrification and denitrification), sulfur (sulfide and sulfur compound oxidation), and manganese cycles (manganese oxidation), exhibited higher abundance in DO depletion sites, except for the iron cycle (iron oxidation). These processes were negatively correlated with DO concentration and positively with SOD (p < 0.05). Overall, the results highlight that aerobic bacteria's metabolic processes consume oxygen, increasing the SOD rate and contributing to DO depletion in the overlying water. Additionally, the study underscores the importance of targeting the removal of in situ microbial molecular mechanisms associated with toxic H2S and CH4 to support reoxygenation efforts in rehabilitating DO depletion sites in the Gan River, aiding in identifying factors controlling DO consumption and offering practical value for the river's restoration and management.

Enhanced Efficiency of Thin‐Film Solar Cells via Cation‐Substituted Kesterite Absorber Layers and Nontoxic Buffers: A Numerical Study

Herein, the 1D Solar Cell Capacitance Simulator software is used to perform numerical analysis of thin‐film solar cells with Cu2ZnSnS4, Cu2BaSnS4, Cu2FeSnS4, and Cu2MnSnS4 absorber layers. The main goal is to investigate the impact of parameters, such as absorber layer thickness, acceptor density, buffer layer, bandgap, and donor density, on the efficiency of these solar cells. The absorber layer investigation entails varying the thickness and the acceptor density to evaluate their influence on the efficiency of the solar cell. A new zinc oxide sulfide (Zn(O,S)) buffer layer is also introduced instead of the conventional cadmium sulfide (CdS) buffer layer. The Zn(O,S) bandgap and its donor density, which are investigated in terms of how they affect the efficiency of the solar cells, have been varied. The optimal values for the thickness of the absorber layer, acceptor density, and the bandgap of the buffer layer are calculated. Subsequently, the donor density is evaluated to find any potential defects that may affect the efficiency of the solar cell. These results confirm that Zn(O,S) can be utilized as a buffer layer. This study concludes that Cu2ZnSnS4, Cu2BaSnS4, and Cu2MnSnS4 absorber layers have superior efficiency in comparison with Cu2FeSnS4.

Reversed oxidative TCA (roTCA) for carbon fixation by an Acidimicrobiia strain from a saline lake.

Acidimicrobiia are widely distributed in nature and suggested to be autotrophic via the Calvin-Benson-Bassham (CBB) cycle. However, direct evidence of chemolithoautotrophy in Acidimicrobiia is lacking. Here, we report a chemolithoautotrophic enrichment from a saline lake, and the subsequent isolation and characterization of a chemolithoautotroph, Salinilacustristhrix flava EGI L10123T, which belongs to a new Acidimicrobiia family. Although strain EGI L10123T is autotrophic, neither its genome nor Acidimicrobiia metagenome-assembled genomes (MAGs) from the enrichment culture encode genes necessary for the CBB cycle. Instead, genomic, transcriptomic, enzymatic, and stable-isotope probing data hinted at the activity of the reversed oxidative TCA (roTCA) coupled with the oxidation of sulfide as the electron donor. Phylogenetic analysis and ancestral character reconstructions of Acidimicrobiia suggested that the essential CBB gene rbcL was acquired through multiple horizontal gene transfer events from diverse microbial taxa. In contrast, genes responsible for sulfide- or hydrogen-dependent roTCA carbon fixation were already present in the last common ancestor of extant Acidimicrobiia. These findings imply the possibility of roTCA carbon fixation in Acidimicrobiia and the ecological importance of Acidimicrobiia. Further research in the future is necessary to confirm whether these characteristics are truly widespread across the clade.

The bifunctional and reusable catalyst of cerium/L‐arginine on mesoporous KIT‐6 in the chemoselective oxidation of sulfides and homoselective synthesis of tetrahydrobenzo[b]pyrans

In this work, KIT‐6@Schiff‐base@Ce nanocatalyst was synthesized by immobilizing the Ce complex on KIT‐6 mesoporous silica framework modified with 3‐iodopropyltrimethoxysilane group. The surface area, total volume, and average diameter of pores, physical properties, functional groups, organic content, and element combination of the obtained nanocatalyst were identified using different techniques including BET, FT‐IR, XRD, WDX, SEM, and EDX. The KIT‐6@Schiff‐base@Ce was investigated as a novel stable and reusable catalyst with excellent performance for the selective synthesizing of sulfoxide and tetrahydrobenzo[b]pyrans. The designed catalyst successfully oxidized a large number of sulfides using hydrogen peroxide under solvent‐free conditions or in ethanol as a safe, green, and available solvent with good efficiency within short reaction times. Also, KIT‐6@Schiff‐base@Ce catalyzed a number of tetrahydrobenzo[b]pyrans using multicomponent condensation of dimedone, aldehydes, and malononitrile in water/ethanol (1:1) as ideal, safe, green and available solvent.

Synthesis of flower-like covalent organic frameworks for photocatalytic selective oxidation of sulfide

BackgroundCovalent organic frameworks (COFs)-based photocatalysts have garnered significant attention for their potential in highly efficient and selective sulfide oxidation. However, the current synthesis methods of COF-based catalysts involve complex multi-step procedures, and better methods need to be upgraded for synthesis. MethodsIn this study, a flower-like COF-based photocatalyst (f-COFs) was synthesized by one-pot method at room temperature using zinc chloride (ZnCl2) as catalyst. The photocatalytic performance of f-COFs was investigated using methyl phenyl sulfide as substrate. Significant FindingsZinc ions remain on the f-COFs synthesized by this method. EDX analysis and XPS techniques were used to confirm the presence of zinc ions. The presence of zinc ions controls the self-assembly of COFs to form unique flower-like microstructure. Its flower-like microstructure provides a strong light absorption capacity. At the same time, the recombination of charge is inhibited, thus promoting the energy and electron transfer during the photocatalytic reaction. These properties allow reactive oxygen species to be prevalent in the reaction process of f-COFs as a photocatalyst, driving the conversion of methyl phenyl sulfide to sulfoxide within 5 h with excellent performance of 95 % conversion and 99 % selectivity.

Arcobacteraceae are ubiquitous mixotrophic bacteria playing important roles in carbon, nitrogen, and sulfur cycling in global oceans.

Mixotrophy is an important trophic strategy for bacterial survival in the ocean. However, the global relevance and identity of the major mixotrophic taxa remain largely elusive. Here, we combined phylogenetic, metagenomic, and metatranscriptomic analyses to characterize ubiquitous Arcobacteraceae based on our deep-sea in situ incubations and the global data. The phylogenomic tree of Arcobacteraceae is divided into three large clades, among which members of clades A and B are almost all from terrestrial environments, while those of clade C are widely distributed in various marine habitats in addition to some terrestrial origins. All clades harbor genes putatively involved in chitin degradation, sulfide oxidation, hydrogen oxidation, thiosulfate oxidation, denitrification, dissimilatory nitrate reduction to ammonium, microaerophilic respiration, and metal (iron/manganese) reduction. Additionally, in clade C, more unique pathways were retrieved, including thiosulfate disproportionation, ethanol fermentation, methane oxidation, fatty acid oxidation, cobalamin synthesis, and dissimilatory reductions of sulfate, perchlorate, and arsenate. Within this clade, two mixotrophic Candidatus genera represented by UBA6211 and CAIJNA01 harbor genes putatively involved in the reverse tricarboxylic acid pathway for carbon fixation. Moreover, the metatranscriptomic data in deep-sea in situ incubations indicated that the latter genus is a mixotroph that conducts carbon fixation by coupling sulfur oxidation and denitrification and metabolizing organic matter. Furthermore, global metatranscriptomic data confirmed the ubiquitous distribution and global relevance of Arcobacteraceae in the expression of those corresponding genes across all oceanic regions and depths. Overall, these results highlight the contribution of previously unrecognized Arcobacteraceae to carbon, nitrogen, and sulfur cycling in global oceans.IMPORTANCEMarine microorganisms exert a profound influence on global carbon cycling and ecological relationships. Mixotrophy, characterized by the simultaneous utilization of both autotrophic and heterotrophic nutrition, has a significant impact on the global carbon cycling. This report characterizes a group of uncultivated bacteria Arcobacteraceae that thrived on the "hot time" of bulky particulate organic matter and exhibited mixotrophic strategy during the in situ organic mineralization. Compared with clades A and B, more unique metabolic pathways were retrieved in clade C, including the reverse tricarboxylic acid pathway for carbon fixation, thiosulfate disproportionation, methane oxidation, and fatty acid oxidation. Global metatranscriptomic data from the Tara Oceans expeditions confirmed the ubiquitous distribution and extensive transcriptional activity of Arcobacteraceae with the expression of genes putatively involved in carbon fixation, methane oxidation, multiple sulfur compound oxidation, and denitrification across all oceanic regions and depths.

Efficient Regioselective Copolymerization of Carbonyl Sulfide and Propylene Oxide with a Tolerant Iron Complex-Based Binary Catalyst

Efficient Regioselective Copolymerization of Carbonyl Sulfide and Propylene Oxide with a Tolerant Iron Complex-Based Binary Catalyst

Magnetic curcumin–copper graphene oxide as facile and recyclable heterogeneous nanocatalyst for preparation of polyhydroquinolines and sulfoxides

In this research project, a versatile procedure has been designed for the preparation of supported copper@curcumin on magnetic graphene oxide nanoparticles (GO@Fe3O4@Cur–Cu). The structure of prepared nanocatalyst was characterized by several techniques including; Fourier transform infrared, powder X-ray diffraction, thermal gravimetric analysis, energy dispersive X-ray analysis, inductively coupled plasma optical emission spectroscopy, vibrating sample magnetometer, transmission electron microscopy, and scanning electron microscopy analyses. The catalytic properties of GO@Fe3O4@Cur–Cu were examined for the efficient synthesis of polyhydroquinolines as well as the preparation of sulfoxides through selective oxidation of sulfides in the presence of hydrogen peroxide.

Exploring the Origins and Evolution of Oxygenic and Anoxygenic Photosynthesis in Deeply Branched Cyanobacteriota.

Cyanobacteriota, the sole prokaryotes capable of oxygenic photosynthesis (OxyP), occupy a unique and pivotal role in Earth's history. While the notion that OxyP may have originated from Cyanobacteriota is widely accepted, its early evolution remains elusive. Here, by using both metagenomics and metatranscriptomics, we explore 36 metagenome-assembled genomes from hot spring ecosystems, belonging to two deep-branching cyanobacterial orders: Thermostichales and Gloeomargaritales. Functional investigation reveals that Thermostichales encode the crucial thylakoid membrane biogenesis protein, vesicle-inducing protein in plastids 1 (Vipp1). Based on the phylogenetic results, we infer that the evolution of the thylakoid membrane predates the divergence of Thermostichales from other cyanobacterial groups and that Thermostichales may be the most ancient lineage known to date to have inherited this feature from their common ancestor. Apart from OxyP, both lineages are potentially capable of sulfide-driven AnoxyP by linking sulfide oxidation to the photosynthetic electron transport chain. Unexpectedly, this AnoxyP capacity appears to be an acquired feature, as the key gene sqr was horizontally transferred from later-evolved cyanobacterial lineages. The presence of two D1 protein variants in Thermostichales suggests the functional flexibility of photosystems, ensuring their survival in fluctuating redox environments. Furthermore, all MAGs feature streamlined phycobilisomes with a preference for capturing longer-wavelength light, implying a unique evolutionary trajectory. Collectively, these results reveal the photosynthetic flexibility in these early-diverging cyanobacterial lineages, shedding new light on the early evolution of Cyanobacteriota and their photosynthetic processes.