Functional Group-driven Competing Mechanism in Electrochemical Reaction and Adsorption/Desorption Processes toward High-capacity Aluminum-Porphyrin Batteries.

Nonaqueous organic aluminum batteries are considered as promising high-safety energy storage devices due to stable ionic liquid electrolytes and Al metals. However, the stability and capacity of organic positive electrodes are limited by their inherent high solubility and low active organic molecules. To address such issues, here porphyrin compounds with rigid molecular structures present stable and reversible capability in electrochemically storing AlCl2+. Comparison between the porphyrin molecules with electron-donating groups (TPP-EDG) and with electron-withdrawing groups (TPP-EWG) suggests that EDG is responsible for increasing both HOMO and LUMO energy levels, resulting in decreased redox potentials. On the other hand, EWG is associated with decreasing both HOMO and LUMO energy levels, leading to promoted redox potentials. EDG and EWG play critical roles in regulating electron density of porphyrin π bond and electrochemical energy storage kinetics behavior. The competitive mechanism between electrochemical redox reaction and de/adsorption processes suggests that TPP-OCH3 delivers the highest specific capacity ~171.8 mAh g-1, approaching a record in the organic Al batteries.

Biochemical, kinetic, and structural characterization of a Bacillus tequilensis nitroreductase.

Nitroreductases (NRs) are NAD(P)H-dependent flavoenzymes that reduce nitro aromatic compounds to their corresponding arylamines via the nitroso and hydroxylamine intermediates. Because of their broad substrate scope and versatility, NRs have found application in multiple fields such as biocatalysis, bioremediation, cell-imaging and prodrug activation. However, only a limited number of members of the broad NR superfamily (> 24 000 sequences) have been experimentally characterized. Within this group of enzymes, only few are capable of amine synthesis, which is a fundamental chemical transformation for the pharmaceutical, agricultural, and textile industries. Herein, we provide a comprehensive description of a recently discovered NR from Bacillus tequilensis, named BtNR. This enzyme has previously been demonstrated to have the capability to fully convert nitro aromatic and heterocyclic compounds to their respective primary amines. In this study, we determined its biochemical, kinetic and structural properties, including its apparent melting temperature (Tm) of 59 °C, broad pH activity range (from pH 3 to 10) and a notably low redox potential (-236 ± 1 mV) in comparison to other well-known NRs. We also determined its steady-state and pre-steady-state kinetic parameters, which are consistent with other NRs. Additionally, we elucidated the crystal structure of BtNR, which resembles the well-characterized Escherichia coli oxygen-insensitive NAD(P)H nitroreductase (NfsB), and investigated the substrate binding in its active site through docking and molecular dynamics studies with four nitro aromatic substrates. Guided by these structural analyses, we probed the functional roles of active site residues by site-directed mutagenesis. Our findings provide valuable insights into the biochemical and structural properties of BtNR, as well as its potential applications in biotechnology.

Reactive nitrogen species act as the enhancers of glutathione pool in embryonic axes of apple seeds subjected to accelerated ageing.

MAIN CONCLUSION: Reactive nitrogen species mitigate the deteriorative effect of accelerated seed ageing by affecting the glutathione concentration and activities of GR and GPX-like. The treatment of apple (Malus domestica Borkh.) embryos isolated from accelerated aged seeds with nitric oxide-derived compounds increases their vigour and is linked to the alleviation of the negative effect of excessive oxidation processes. Reduced form of glutathione (GSH) is involved in the maintenance of redox potential. Glutathione peroxidase-like (GPX-like) uses GSH and converts it to oxidised form (GSSG), while glutathione reductase (GR) reduces GSSG into GSH. The aim of this work was to investigate the impact of the short-time NOx treatment of embryos isolated from apple seeds subjected to accelerated ageing on glutathione-related parameters. Apple seeds were subjected to accelerated ageing for 7, 14 or 21 days. Isolated embryos were shortly treated with NOx and cultured for 48 h. During ageing, in the axes of apple embryos, GSH and GSSG levels as well as half-cell reduction potential remained stable, while GR and GPX-like activities decreased. However, the positive effect of NOx in the vigour preservation of embryos isolated from prolonged aged seeds is linked to the increased total glutathione pool, and above all, higher GSH content. Moreover, NOx increased the level of transcripts encoding GPX-like and stimulated enzymatic activity. The obtained results indicate that high seed vigour related to the mode of action of NO and its derivatives is closely linked to the maintenance of higher GSH levels.

Recognition of environmental contaminant and pathogenic bacteria by means of redox potential methodology.

The time-consuming nature of culturing methods has urged the exploration of rapid modern technologies. One promising alternative utilizes redox potential, which describes the oxidative changes within complex media, indicating oxygen and nutrient consumption, as well as the production of reduced substances in the investigated biological system. Redox potential measurement can detect microbial activity within 16 h, what is significantly faster than the minimum 24 h incubation time of the reference plate counting technique. The redox potential based method can be specific with selective media, but bacterial strains have unique kinetic pattern as well. The proposed method suggests evaluation of the curve shape for the differentiation of environmental contaminant and pathogenic microbial strains. Six bacterial species were used in validation (Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Listeria innocua, Listeria monocytogenes, and Listeria ivanovii). Descriptive parameters reached 98.2 % accuracy and Gompertz model achieved 91.6 % accuracy in classification of the selected 6 bacteria species.•Mathematical model (Gompertz function) and first order descriptive parameters are suggested to describe the specific shape of redox potential curves, while Support Vector Machine (SVM) is recommended for classification.•Due to the concentration dependent time to detection (TTD), pre-processing applies standardization according to the inflection point time.

Redox Potential Based Self-Powered Electrochromic Devices for Smart Windows.

Energy-efficient glass windows are pivotal in modern infrastructure striving toward the "Zero energy" concept. Electrochromic (EC) energy storage devices emerge as a promising alternative to conventional glass, yet their widespread commercialization is impeded by high costs and dependence on external power sources. Addressing this, redox potential-based self-powered electrochromic (RP-SPEC) devices are introduced leveraging established EC materials like tungsten oxide (WO3) and vanadium-doped nickel oxide (V-NiO) along with aluminum (Al) as an anode. These devices produce open circuit voltages (OCV) exceeding ±0.3 V, enabling autonomous operation for multiple cycles. The WO3 film exhibits 1% transmission and 88% modulation in the colored state at 550 nm with a mere 260 nm thickness. The redox interactions facilitate coloring and bleaching cycles without external power, while photo-charging rejuvenates the system. Notably, the inherent voltages of the RP-SPEC device offer dual functionality, powering electronic devices for up to 81 h. Large-area (≈28 cm2) device feasibility is demonstrated, paving the way for industrial adoption. The RP-SPEC device promises to revolutionize smart window technology by offering both energy efficiency and autonomous operation, thus advancing sustainable infrastructure.

Pectin supplementation accelerates post-antibiotic gut microbiome reconstitution orchestrated with reduced gut redox potential.

Antibiotic-induced gut dysbiosis (AID) presents a big challenge to host health, and the recovery from this dysbiosis is often slow and incomplete. AID is typically characterized by elevation in redox potential, Enterobacteriaceae load, and aerobic metabolism. In our previous study, a pectin-enriched diet was demonstrated to decrease fecal redox potential and modulate the gut microbiome. Therefore, we propose that pectin supplementation may modulate gut redox potential and favor post-antibiotic gut microbiome reconstitution from dysbiosis. In the present study, rats with AIDwere used to investigate the effects of pectin supplementation on post-antibiotic gut microbiome reconstitution from dysbiosis. The results showed that pectin supplementation accelerated post-antibiotic reconstitution of gut microbiome composition and function and led to enhancement of anabolic reductive metabolism and weakening of catabolic oxidative pathways. These results were corroborated by the measurement of redox potential, findings suggesting that pectin favors post-antibiotic recovery from dysbiosis. Pectin-modulated fecal microbiota transplantation accelerated the decrease in antibiotics-elevated redox potential and Enterobacteriaceae load similarly to pectin supplementation. Moreover, both pectin supplementation and Pectin-modulated fecal microbiota transplantation enriched anaerobic members, primarily from Lachnospiraceae orchestration with enhancement of microbial reductive metabolism in post-antibiotic rats. These findings suggested that pectin supplementation accelerated post-antibiotic gut microbiome reconstitution orchestrated with reduced gut redox potential and that the effect of pectin on redox potential was mediated by remodeling of the intestinal microbiota.

Potential-Regulated Design for Direct Recycling of Degraded LiFePO4 Cathode.

The rapid proliferation of power sources equipped with lithium-ion batteries poses significant challenges in terms of post-scrap recycling and environmental impacts, necessitating urgent attention to the development of sustainable solutions. The cathode direct regeneration technologies present an optimal solution for the disposal of degraded cathodes, aiming to non-destructively re-lithiate and straightforwardly reuse degraded cathode materials with reasonable profits and excellent efficiency. Herein, a potential-regulated strategy is proposed for the direct recycling of degraded LiFePO4 cathodes, utilizing low-cost Na2SO3 as a reductant with lower redox potential in the alkaline systems. The aqueous re-lithiation approach, as a viable alternative, not only enables the re-lithiation of degraded cathode while ignoring variation in Li loss among different feedstocks but also utilizes the rapid sintering process to restore the cathode microstructure with desirable stoichiometry and crystallinity. The regenerated LiFePO4 exhibits enhanced electrochemical performance with a capacity of 144 mA h g-1 at 1 C and a high retention of 98% after 500 cycles at 5 C. Furthermore, this present work offers considerable prospects for the industrial implementation of directly recycled materials from lithium-ion batteries, resulting in improved economic benefits compared to conventional leaching methods.

Predicting redox potentials by graph-based machine learning methods.

The evaluation of oxidation and reduction potentials is a pivotal task in various chemical fields. However, their accurate prediction by theoretical computations, which is a complementary task and sometimes the only alternative to experimental measurement, may be often resource-intensive and time-consuming. This paper addresses this challenge through the application of machine learning techniques, with a particular focus on graph-based methods (such as graph edit distances, graph kernels, and graph neural networks) that are reviewed to enlighten their deep links with theoretical chemistry. To this aim, we establish the ORedOx159 database, a comprehensive, homogeneous (with reference values stemming from density functional theory calculations), and reliable resource containing 318 one-electron reduction and oxidation reactions and featuring 159 large organic compounds. Subsequently, we provide an instructive overview of the good practice in machine learning and of commonly utilized machine learning models. We then assess their predictive performances on the ORedOx159 dataset through extensive analyses. Our simulations using descriptors that are computed in an almost instantaneous way result in a notable improvement in prediction accuracy, with mean absolute error (MAE) values equal to 5.6 kcal mol - 1 $$ {}^{-1} $$ for reduction and 7.2 kcal mol - 1 $$ {}^{-1} $$ for oxidation potentials, which paves a way toward efficient in silico design of new electrochemical systems.

Experimental and Theoretical Predictors for Redox Potentials of Bispyridinylidene Electron Donors.

Bispyridinylidenes are neutral organic molecules capable of two-electron oxidation at a range of redox potentials that are widely tunable by choice of substituent, making them attractive as homogeneous organic reductants and active materials in redox flow batteries. In an effort to readily predict the redox potentials of this important class of compounds, we have developed correlations between the experimental redox potentials and both experimental and theoretical predictors. On the experimental side, we show that multinuclear NMR chemical shifts of related pyridinium ions correlate well with the redox potentials of bispyridinylidenes, with R2 and standard errors (S) reaching 0.9810 and 0.048 V, respectively, when the 13C (N-CH3) and 1H (ortho) chemical shifts are used together. Theoretical studies of the bispyridinylidenes and their doubly oxidized bipyridinium ions gave a range of predictively valuable equations at various levels of computational cost. This ranged from a simple model using only the EHOMO of the bispyridinylidenes (R2=0.9689; S=0.060 V), to a more computationally intensive model which include solvation effects for both redox states which gave the highest predictive value for all methods (R2=0.9958; S=0.022 V). This work will guide further studies of this important class of molecules.

Towards High-Performance Photo-Fenton Degradation of Organic Pollutants with Magnetite-Silver Composites: Synthesis, Catalytic Reactions and In Situ Insights.

In this study, Fe3O4/Ag magnetite-silver (MSx) nanocomposites were investigated as catalysts for advanced oxidation processes by coupling the plasmonic effect of silver nanoparticles and the ferromagnetism of iron oxide species. A surfactant-free co-precipitation synthesis method yielded pure Fe3O4 magnetite and four types of MSx nanocomposites. Their characterisation included structural, compositional, morphological and optical analyses, revealing Fe3O4 magnetite and Ag silver phases with particle sizes ranging from 15 to 40 nm, increasing with the silver content. The heterostructures with silver reduced magnetite particle aggregation, as confirmed by dynamic light scattering. The UV-Vis spectra showed that the Fe:Ag ratio strongly influenced the absorbance, with a strong absorption band around 400 nm due to the silver phase. The oxidation kinetics of organic pollutants, monitored by in situ luminescence measurements using rhodamine B as a model system, demonstrated the higher performance of the developed catalysts with increasing Ag content. The specific surface area measurements highlighted the importance of active sites in the synergistic catalytic activity of Fe3O4/Ag nanocomposites in the photo-Fenton reaction. Finally, the straightforward fabrication of diverse Fe3O4/Ag heterostructures combining magnetism and plasmonic effects opens up promising possibilities for heterogeneous catalysis and environmental remediation.

Redox-mediated changes in the release dynamics of lead (Pb) and bacterial community composition in a biochar amended soil contaminated with metal halide perovskite solar panel waste.

This study explored the redox-mediated changes in a lead (Pb) contaminated soil (900 mg/kg) due to the addition of solar cell powder (SC) and investigated the impact of biochar derived from soft wood pellet (SWP) and oil seed rape straw (OSR) (5% w/w) on Pb immobilization using an automated biogeochemical microcosm system. The redox potential (Eh) of the untreated (control; SC) and biochar treated soils (SC + SWP and SC + OSR) ranged from -151 mV to +493 mV. In SC, the dissolved Pb concentrations were higher under oxic (up to 2.29 mg L-1) conditions than reducing (0.13 mg L-1) conditions. The addition of SWP and OSR to soil immobilized Pb, decreased dissolved concentration, which could be possibly due to the increase of pH, co-precipitation of Pb with FeMn (hydro)oxides and pyromorphite, and complexation with biochar surface functional groups. The ability and efficiency of OSR for Pb immobilization were higher than SWP, owing to the higher pH and density of surface functional groups of OSR than SWP. Biochar enhanced the relative abundance of Proteobacteria irrespective of Eh changes, while the relative abundance of Bacteroidota increased under oxidizing conditions. Overall, we found that both OSR and SWP immobilized Pb in solar panel waste contaminated soil under both oxidizing and reducing redox conditions which may mitigate the potential risk of Pb contamination.

Characterization of the iron-sulfur clusters in the nitrogenase-like reductase CfbC/D required for coenzyme F430 biosynthesis.

Coenzyme F430 is a nickel-containing tetrapyrrole, serving as the prosthetic group of methyl-coenzyme M reductase in methanogenic and methanotrophic archaea. During coenzyme F430 biosynthesis, the tetrapyrrole macrocycle is reduced by the nitrogenase-like CfbC/D system consisting of the reductase component CfbC and the catalytic component CfbD. Both components are homodimeric proteins, each carrying a [4Fe-4S] cluster. Here, the ligands of the [4Fe-4S] clusters of CfbC2 and CfbD2 were identified revealing an all cysteine ligation of both clusters. Moreover, the midpoint potentials of the [4Fe-4S] clusters were determined to be -256 mV for CfbC2 and -407 mV for CfbD2. These midpoint potentials indicate that the consecutive thermodynamically unfavorable 6 individual "up-hill" electron transfers to the organic moiety of the Ni2+-sirohydrochlorin a,c-diamide substrate require an intricate interplay of ATP-binding, hydrolysis, protein complex formation and release to drive product formation, which is a common theme in nitrogenase-like systems.

Generation, Characterization and Reactivity of a High-Valent Mononuclear Cobalt(IV)-Diazide Complex.

High-valent Fe(IV)=O intermediates of metalloenzymes have inspired numerous efforts to generate synthetic analogs to mimic and understand their substrate oxidation reactivities. However, high-valent M(IV) complexes of late transition metals are rare. We have recently reported a novel Co(IV)-dinitrate complex (1-NO3) that activates sp3 C-H bonds up to 87 kcal/mol. In this work, we have shown that the nitrate ligands in 1-NO3 can be replaced by azide, a more basic coordinating base, resulting in the formation of a more potent Co(IV)-diazide species (1-N3) that reacts with substrates (hydrocarbons and phenols) at faster rate constants and activates stronger C-H bonds than the parent complex 1-NO3. We have characterized 1-N3 employing a combination of spectroscopic and computational approaches. Our results clearly show that the coordination of azide leads to the modulation of the Co(IV) electronic structure and the Co(IV/III) redox potential. Together with the higher basicity of azide, these thermodynamic parameters contribute to the higher driving forces of 1-N3 than 1-NO3 for C-H bond activation. Our discoveries are thus insightful for designing more reactive bio-inspired high-valent late transition metal complexes for activating inert aliphatic hydrocarbons.

The Catalysis Mechanism of E. coli Nitroreductase A, a Candidate for Gene-Directed Prodrug Therapy: Potentiometric and Substrate Specificity Studies.

E. coli nitroreductase A (NfsA) is a candidate for gene-directed prodrug cancer therapy using bioreductively activated nitroaromatic compounds (ArNO2). In this work, we determined the standard redox potential of FMN of NfsA to be -215 ± 5 mV at pH 7.0. FMN semiquinone was not formed during 5-deazaflavin-sensitized NfsA photoreduction. This determines the two-electron character of the reduction of ArNO2 and quinones (Q). In parallel, we characterized the oxidant specificity of NfsA with an emphasis on its structure. Except for negative outliers nitracrine and SN-36506, the reactivity of ArNO2 increases with their electron affinity (single-electron reduction potential, E17) and is unaffected by their lipophilicity and Van der Waals volume up to 386 Å. The reactivity of quinoidal oxidants is not clearly dependent on E17, but 2-hydroxy-1,4-naphthoquinones were identified as positive outliers and a number of compounds with diverse structures as negative outliers. 2-Hydroxy-1,4-naphthoquinones are characterized by the most positive reaction activation entropy and the negative outlier tetramethyl-1,4-benzoquinone by the most negative. Computer modelling data showed that the formation of H bonds with Arg15, Arg133, and Ser40, plays a major role in the binding of oxidants to reduced NfsA, while the role of the π-π interaction of their aromatic structures is less significant. Typically, the calculated hydride-transfer distances during ArNO2 reduction are smallwer than for Q. This explains the lower reactivity of quinones. Another factor that slows down the reduction is the presence of positively charged aliphatic substituents.

Determinant Factors for Ongoing Pregnancy in Homologous Intrauterine Insemination Cycles - A Prospective Study.

BACKGROUND/AIM: Intrauterine insemination (IUI) is the most common assisted-reproduction treatment. However, it has lower success rate in comparison to other treatments. Therefore, determining factors that contribute to IUI success is of particular interest and this was the purpose of this prospective study. PATIENTS AND METHODS: In this study, only homologous inseminations with fresh semen samples were included. All women received mild ovarian stimulation with clomiphene citrate and gonadotropins. Before IUI, basic semen analysis, evaluation of DNA fragmentation index (DFI), as well as measurement of sperm redox potential, were performed on each semen sample. Semen was processed with density-gradient centrifugation and 500 µl of processed sperm was used for insemination. RESULTS: In 200 cycles, there were 36 pregnancies, six of them ectopic. Cycles with ongoing pregnancies were characterized by younger male and female age and higher number of follicles. Multivariate logistic regression analysis showed that only female age was significantly associated with ongoing pregnancy. DFI was positively correlated with male age and negatively correlated with sperm concentration and progressive motility. Semen redox potential showed a strong negative correlation with sperm concentration and positive correlation with DFI. CONCLUSION: Female age seems to be the most important determinant factor for the achievement of an ongoing pregnancy in homologous IUI cycles with fresh semen.

Redox potential model for guiding moderate oxidation of polycyclic aromatic hydrocarbons in soils.

In-situ chemical oxidation is an important approach to remediate soils contaminated with persistent organic pollutants, e.g., polycyclic aromatic hydrocarbons (PAHs). However, massive oxidants are added into soils without an explicit model for predicting the redox potential (Eh) during soil remediation, and overdosed oxidants would pose secondary damage by disturbing soil organic matter and acidity. Here, a soil redox potential (Eh) model was first established to quantify the relationship among oxidation parameters, crucial soil properties, and pollutant elimination. The impacts of oxidant types and doses, soil pH, and soil organic carbon contents on soil Eh were systematically clarified in four commonly used oxidation systems (i.e., KMnO4, H2O2, fenton, and persulfate). The relative error of preliminary Eh model was increased from 48-62% to 4-16% after being modified with the soil texture and dissolved organic carbon, and this high accuracy was verified by 12 actual PAHs contaminated soils. Combining the discovered critical oxidation potential (COP) of PAHs, the moderate oxidation process could be regulated by the guidance of the soil Eh model in different soil conditions. Moreover, the product analysis revealed that the hydroxylation of PAHs occurred most frequently when the soil Eh reached their COP, providing a foundation for further microorganism remediation. These results provide a feasible strategy for selecting oxidants and controlling their doses toward moderate oxidation of contaminated soils, which will reduce the consumption of soil organic matter and protect the main structure and function of soil for future utilization. ENVIRONMENTAL IMPLICATIONS: This study provides a novel insight into the moderate chemical oxidation by the Eh model and largely reduces the secondary risks of excessive oxidation and oxidant residual in ISCO. The moderate oxidation of PAHs could be a first step to decrease their toxicity and increase their bioaccessibility, favoring the microbial degradation of PAHs. Controlling the soil Eh with the established model here could be a promising approach to couple moderate oxidation of organic contaminants with microbial degradation. Such an effective and green soil remediation will largely preserve the soil's functional structure and favor the subsequent utilization of remediated soil.

Antioxidant Activity of Humulus lupulus Phenolic Hop Extracts in Creating a New Pâté: An Element Affecting Fat Stability and Microbiological Quality during Storage.

The aim of this study was to evaluate the effect of hop extracts on changes in the primary and secondary fat oxidation products, physicochemical properties, and microbiological quality of pâté-type offal sausages obtained through the partial replacement of animal fat with vegetable fat. This study demonstrated that the extraction efficiency varied among hop cone varieties, with the highest efficiency observed for the Lubelski variety and the lowest for the Magnum variety. The phenolic compound content was higher in the Magnum cones (2.74 ± 0.11 mg/g dry matter) compared to the Lubelska cones (2.27 ± 0.05 mg/g of product). Additionally, the DPPH radical scavenging activity was greater in the extract from the Magnum cones (4.21 ± 0.09 mg TE/g d.w.) than in the extract from the Lublelski cones (3.87 ± 0.05 mg TE/ g d.w.). Similarly, the extracts from the Lubelski cones exhibited a higher antiradical activity against the ABTS radical compared to the extract from Magnum cones. Throughout storage, a significant increase in the pH value was observed in the control sample and in the samples with a 20% replacement of animal fat with rapeseed oil and Magnum hop extract. However, the addition of Lubelski hop extract resulted in a decrease in the pH value during the 15-day storage period. The samples with a 20% replacement of animal fat with rapeseed oil and 0.1% Lubelski hop extract showed the least changes in water activity during storage. The samples with a 20% replacement of animal fat with rapeseed oil and the addition of 0.2% Lubelski hop extract had the lowest peroxide value and TBARS index throughout the storage period. The addition of hop extract inhibited the growth of the total number of microorganisms in the tested sausages. In the samples with a 20% replacement of animal fat with rapeseed oil, the content of aerobic microorganisms, compared to the control sample, was statistically significantly lower.

The Selenoproteome as a Dynamic Response Mechanism to Oxidative Stress in Hydrogenotrophic Methanogenic Communities.

Methanogenesis is a critical process in the carbon cycle that is applied industrially in anaerobic digestion and biogas production. While naturally occurring in diverse environments, methanogenesis requires anaerobic and reduced conditions, although varying degrees of oxygen tolerance have been described. Microaeration is suggested as the next step to increase methane production and improve hydrolysis in digestion processes; therefore, a deeper understanding of the methanogenic response to oxygen stress is needed. To explore the drivers of oxygen tolerance in methanogenesis, two parallel enrichments were performed under the addition of H2/CO2 in an environment without reducing agents and in a redox-buffered environment by adding redox mediator 9,10-anthraquinone-2,7-disulfonate disodium. The cellular response to oxidative conditions is mapped using proteomic analysis. The resulting community showed remarkable tolerance to high-redox environments and was unperturbed in its methane production. Next to the expression of pathways to mitigate reactive oxygen species, the higher redox potential environment showed an increased presence of selenocysteine and selenium-associated pathways. By including sulfur-to-selenium mass shifts in a proteomic database search, we provide the first evidence of the dynamic and large-scale incorporation of selenocysteine as a response to oxidative stress in hydrogenotrophic methanogenesis and the presence of a dynamic selenoproteome.

Soil redox status governs within-field spatial variation in microbial arsenic methylation and rice straighthead disease.

Microbial arsenic (As) methylation in paddy soil produces mainly dimethylarsenate (DMA), which can cause physiological straighthead disease in rice. The disease is often highly patchy in the field, but the reasons remain unknown. We investigated within-field spatial variations in straighthead disease severity, As species in rice husks and in soil porewater, microbial composition and abundance of arsM gene encoding arsenite S-adenosylmethionine methyltransferase in two paddy fields. The spatial pattern of disease severity matched those of soil redox potential, arsM gene abundance, porewater DMA concentration, and husk DMA concentration in both fields. Structural equation modelling identified soil redox potential as the key factor affecting arsM gene abundance, consequently impacting porewater DMA and husk DMA concentrations. Core amplicon variants that correlated positively with husk DMA concentration belonged mainly to the phyla of Chloroflexi, Bacillota, Acidobacteriota, Actinobacteriota, and Myxococcota. Meta-omics analyses of soil samples from the disease and non-disease patches identified 5129 arsM gene sequences, with 71% being transcribed. The arsM-carrying hosts were diverse and dominated by anaerobic bacteria. Between 96 and 115 arsM sequences were significantly more expressed in the soil samples from the disease than from the non-disease patch, which were distributed across 18 phyla, especially Acidobacteriota, Bacteroidota, Verrucomicrobiota, Chloroflexota, Pseudomonadota, and Actinomycetota. This study demonstrates that even a small variation in soil redox potential within the anoxic range can cause a large variation in the abundance of As-methylating microorganisms, thus resulting in within-field variation in rice straighthead disease. Raising soil redox potential could be an effective way to prevent straighthead disease.

Indium Nitride Nanowires: Low Redox Potential Anodes for Lithium-Ion Batteries.

Advanced lithium-ion batteries (LIBs) are crucial to portable devices and electric vehicles. However, it is still challenging to further develop the current anodic materials such as graphite due to the intrinsic limited capacity and sluggish Li-ion diffusion. Indium nitride (InN), which is a new type of anodic material with low redox potential (<0.7 V vs Li/Li+) and narrow bandgap (0.69 eV), may serve as a new high-energy density anode material for LIBs. Here, the growth of 1D single crystalline InN nanowires is reported on Au-decorated carbon fibers (InN/Au-CFs) via chemical vapor deposition, possessing a high aspect ratio of 400. The binder-free Au-CFs with high conductivity can provide abundant sites and enhance binding force for the dense growth of InN nanowires, displaying shortened Li ion diffusion paths, high structural stability, and fast Li+ kinetics. The InN/Au-CFs can offer stable and high-rate Li delithiation/lithiation without Li deposition, and achieve a remarkable capacity of 632.5 mAh g-1 at 0.1 A g-1 after 450 cycles and 416 mAh g-1 at a high rate of 30 A g-1. The InN nanowires as battery anodes shall hold substantial promise for fulfilling superior long-term cycling performance and high-rate capability for advanced LIBs.