Search Results (82)

Quorum sensing (QS) is critically involved in mediating microbial interactions and serves as a central regulatory mechanism in bacterial pathogenesis. As an emerging countermeasure, quorum quenching (QQ) suppresses QS-regulated virulence through enzymatic or chemical disruption of signal systems. N-acyl homoserine lactone (AHL), an evolutionarily conserved QS signal, coordinates the pathogenicity of multiple plant pathogens, particularly Dickeya zeae, which causes soft rot disease in various crops and leads to substantial agricultural losses. In this study, the QQ strain Acinetobacter schindleri XJ-10 was evaluated for its capacity to degrade AHL and attenuate the pathogenicity of D. zeae EC1 in host plants. Notably, strain XJ-10 exhibited efficient AHL degradation at 0.2 mmol/L within 24 h, achieving a degradation efficiency of 98.80%. Subsequently, gas chromatography–mass spectrometry (GC-MS) analysis identified N-hexanoyl-L-homoserine lactone and propanamide as key intermediates during AHL degradation, confirming complete mineralization to CO₂ and H₂O. Based on the structural characterization of AHL and its intermediates, the metabolic pathway within strain XJ-10 was proposed. The degradation pathway initiates with the hydrolysis of the ester ring of N-hexanoyl-L-homoserine lactone, generating N-hexanoyl-L-homoserine. Subsequent carbon–nitrogen bond scission is predicted to yield N-cyclohexyl-propanamide, which is further catabolized to produce hexanamide and propanamide. Furthermore, strain XJ-10 exhibited biocontrol activity against soft rot disease affecting potato (Solanum tuberosum), radish (Raphanus sativus), and Chinese cabbage (Brassica rapa subsp. pekinensis), as its crude enzyme extract effectively reduced disease incidence and severity in planta. While strain XJ-10 showed no detectable acylase activity, it exhibited significant degradation activity against AHL, suggesting a distinct QQ mechanism. Collectively, these findings broaden the scope of QQ-based biocontrol strategies and enhance mechanistic insights into managing bacterial diseases through QS modulation. Full article

Accurate prediction of NO emissions is important for the development of low-emission gas turbine combustors. This study evaluates several NO formation models for a 78 MW F-class gas turbine using a decoupled post-processing framework. Steady RANS simulations were performed with a partially premixed flamelet/PDF combustion model. Thermal NO, prompt NO, the N₂O intermediate pathway, and turbulence–chemistry interaction were assessed at 50% and 100% load. Thermal NO was the dominant pathway and showed strong load dependence. Using partial equilibrium for O radicals increased outlet NO by 16.46% at 50% load and 43.69% at 100% load. Including partial-equilibrium OH further increased NO by 8.67% at 50% load but had little effect at full load. Prompt NO remained on the order of 10⁻³ ppm. The N₂O pathway and turbulence–chemistry interaction also affected the prediction, especially at full load. The selected model was further compared with field measurements during load ramping and pilot-ratio variation. Most load-ramping predictions agreed with measurements within 18%. The results demonstrate the applicability of the proposed framework for engineering NO emission prediction while also identifying limitations under transitional operating conditions. Full article

A high-performance Z-scheme Ho₂BiNbO₇/ZnBiTmO₄ heterojunction (HZ) photocatalyst was prepared for the first time using a wet impregnation method. The HZ photocatalyst significantly improved the separation efficiency of the photoinduced electrons and the photoinduced holes; meanwhile, the HZ photocatalyst could effectively broaden the visible light spectrum via a specific mechanism of the Z-scheme heterojunction structure. The experimental results displayed that the HZ photocatalyst had strong catalytic activity when the brilliant green (BLG) was degraded. In particular, the degradation rate of BLG when using the HZ photocatalyst was found to be 99.47%, and the mineralization efficiency of the total organic carbon (TOC) concentration was found to be 98.26% when using the HZ photocatalyst under visible light irradiation (VILIIR). The HZ photocatalyst possessed higher photocatalytic activity compared with Ho₂BiNbO₇, ZnBiTmO₄, or N-doped TiO₂ (N-T). The degradation rate of BLG when using the HZ photocatalyst was 1.27 times higher than that when using Ho₂BiNbO₇, 1.15 times higher than that when employing ZnBiTmO₄, or 2.91 times higher than that when using N-T under VILIIR. The mineralization efficiency of the TOC concentration after catalytic degradation of BLG when employing the HZ photocatalyst was 1.31 times higher than that when employing Ho₂BiNbO₇, 1.19 times higher than that when employing ZnBiTmO₄, or 3.14 times higher than that when using N-T under VILIIR. The experimental generating radicals confirmed that the HZ photocatalyst might produce diverse reactive radicals, which contained superoxide anions (•O₂⁻), hydroxyl radicals (•OH) and photogenerated holes (h⁺) after catalytic degradation of BLG. The descending order of oxidizing capacity for above three radicals was as follows: •OH > •O₂⁻ > h⁺. The descending order of the photocatalytic activity for the four photocatalysts was as follows: HZ > ZnBiTmO₄ > Ho₂BiNbO₇ > N-T. The intermediate degradation products of BLG were detected by employing the HZ photocatalyst during the photocatalytic degradation process of BLG; the reliability, reusability, and stability of the HZ photocatalyst were proven by quintic cyclical degradation experiments of BLG. This study developed the degradation pathways and degradation mechanism of BLG when using the HZ photocatalyst under VILIIR. This work supplies novel thought for the design and manufacture of Z-scheme heterojunction catalysts, and it provides a basis for developing an efficient environmental remediation technique for BLG pollution. Full article

Sulfur hexafluoride (SF₆) serves as an essential insulating and arc-extinguishing medium in power facilities, while it is an extremely potent greenhouse gas with an ultra-long atmospheric lifetime. To realize efficient medium-temperature harmless disposal of waste SF₆, two-dimensional stable C₄N monolayers were adopted as substrates to load ZnO and CuO nanoparticles for composite catalyst fabrication. XRD, TEM, and EDS characterizations confirmed the uniform dispersion of the metal oxides without destroying the C₄N two-dimensional skeleton. Comparative experiments proved that an NH₃ reducing atmosphere significantly accelerates SF₆ decomposition. The 3:1 CuO-modified catalyst achieved a maximum SF₆ conversion of 91%, and a CaO additive effectively restrained high-temperature sintering and irreversible HF halogen poisoning, boosting overall catalytic efficiency by approximately 30%. DFT adsorption simulations revealed totally different active centers: hollow sites dominate ZnO-C₄N with broad adsorption capacity for SO₂, SO₂F₂, and other fluorinated intermediates, whereas surface O sites of CuO-C₄N exhibit exclusive strong chemisorption toward SO₂. Combined with macroscopic kinetics and atomic-scale interfacial interaction rules, their distinct stepwise defluorination pathways were illustrated. This study offers solid experimental data and microscopic theoretical guidance for designing advanced C₄N-based catalysts for waste SF₆ abatement. Full article

Supported Pt catalysts are highly active for the selective catalytic oxidation of ammonia (NH₃-SCO), but their practical use is limited by poor N₂ selectivity and insufficient hydrothermal durability under high-temperature exhaust conditions. Herein, we report a composition-regulated high-entropy oxide interface strategy to stabilize Pt–Cu dual sites and steer NH₃ oxidation toward selective N₂ formation. A series of fluorite-type Ce-based high-entropy oxides, including CeZrLaPrYO_x, CeSmLaPrYO_x, and CeSnLaPrYO_x, were constructed as thermally robust supports for Pt and Cu loading. Among them, PtCu/HEO-Zr calcined at 1000 °C exhibits the best NH₃-SCO performance, achieving 90% NH₃ conversion at 260 °C while maintaining N₂ selectivity above 80% over a broad temperature window of 100–300 °C under a high weight hourly space velocity of 100,000 mL·g⁻¹·h⁻¹. More importantly, after harsh hydrothermal aging at 800 °C with 10 vol% H₂O for 12 h, the catalyst shows negligible activity loss and nearly unchanged N₂ selectivity, demonstrating exceptional structural and catalytic robustness. Structural and surface analyses reveal that Zr incorporation optimizes the fluorite high-entropy lattice, increases oxygen vacancy concentration, promotes lattice oxygen mobility, strengthens surface acidity, and enriches active Cu²⁺ species, thereby enhancing the interfacial cooperation between NH₃ activation and oxygen-assisted intermediate conversion. In situ DRIFTS further reveals that PtCu/HEO-Zr favors an O_lat-assisted internal selective catalytic reduction pathway, in which adsorbed NH₃ is activated to -NH₂ species and subsequently reacts with lattice oxygen-derived intermediates to form N₂O₂²⁻-like species that decompose into N₂ and H₂O. Meanwhile, the formation of nonselective NO_x and N₂O products is suppressed. This work highlights high-entropy oxide-supported Pt–Cu interfaces as a promising platform for designing hydrothermally durable and N₂-selective NH₃-SCO catalysts. Full article

Advanced oxidation processes based on peracetic acid (PAA) have emerged as a sustainable strategy for water treatment; however, developing efficient, stable, and environmentally friendly catalysts remains challenging. In this study, a functional cobalt-based catalyst (CPBC_x) was fabricated by immobilizing cobalt ions onto phytic-acid-modified biochar to active PAA for the degradation of sulfamethoxazole (SMX). The effect of pyrolysis temperature on the catalytic performance was investigated, with CPBC₈ showing the highest SMX degradation efficiency, under the conditions of a CPBC8 dosage of 200 mg/L, a PAA concentration of 0.2 mM, and an initial SMX concentration of 5 mg/L, and a 99.0% removal of SMX was achieved within 10 min. Moreover, the removal efficiency remained above 90% after five consecutive cycles. Mechanistic analysis revealed that biochar, acting as an efficient electron shuttle, enhanced electron transfer and accelerated the Co²⁺/Co³⁺ redox cycle, thereby shifting the SMX degradation pathway from a radical-dominated route to a non-radical one dominated by singlet oxygen (¹O₂). Density functional theory (DFT) calculations identified the vulnerable attack site (N11) on the SMX molecule. Transformation products and degradation pathways were elucidated using ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-TOF-MS), and the identified intermediates exhibited low ecotoxicity. Furthermore, the CPBC₈ composite demonstrated sustained degradation rates, good stability, and environmental compatibility for practical application. This study provides a sustainable and efficient solution for applying biochar-based PAA advanced oxidation processes in water treatment. Full article

Galectin-3 (Gal-3) is a β-galactoside-binding lectin implicated in metabolic inflammation, cardiovascular and renal dysfunction, neurodegenerative disorders, and obesity-related pathologies. Although Gal-3 is recognized as a clinically relevant biomarker, the mechanisms controlling its tissue expression and circulating abundance remain poorly defined. O-GlcNAcase (Oga; encoded by Mgea5), the enzyme that removes O-linked β-N-acetylglucosamine (O-GlcNAc) from proteins, regulates nutrient-sensitive signaling and transcriptional processes that overlap with Gal-3 associated disease pathways. To investigate the relationship between metabolic status and Gal-3 expression, male mice were fed a high-fat diet (HFD) for eight weeks to induce obesity. HFD-fed mice exhibited significant increases in body weight and fasting and fed blood glucose levels compared with lean controls, confirming metabolic dysregulation. ELISA revealed approximately threefold higher serum and plasma Gal-3 concentrations in obese mice, indicating enhanced Gal-3 production in diet-induced obesity. To determine whether Oga regulates Gal-3 expression, Oga wild-type (WT), heterozygous (HET), and knockout (KO) mice were analyzed. Circulating Gal-3 protein levels were significantly reduced in Oga KO mice, with intermediate levels in Oga HET animals. RT-qPCR revealed genotype-dependent modulation of Gal-3 (Lgals3) mRNA expression across multiple tissues, demonstrating tissue-specific regulation by Oga. These findings establish Oga as a critical regulator of Gal-3 expression and systemic abundance. The data reveal a mechanistic link between O-GlcNAc signaling enzyme Oga, and lectin-mediated metabolic inflammation, suggesting that Oga activity influences Gal-3 homeostasis and may affect its interpretation as a biomarker in metabolic disease. Full article

Ammonia decomposition over non-precious metal thermos-catalysts offers a viable and cost-effective pathway for sustainable hydrogen production. In this study, LaCeO₃ perovskite was synthesized using a citric acid complexation method and employed as a support for mono- and bimetallic catalysts prepared by incipient wetness impregnation, maintaining a total metal loading of 10 wt%. Structural and surface properties were systematically investigated using BET, XRD, H₂-TPR, SEM, TEM, and CO₂-TPD. Among the monometallic catalysts (Ni, Co, and Fe), 10%Ni/LaCeO₃ exhibited the highest activity, which is attributed to its enhanced reducibility and optimal surface basicity, facilitating NH₃ activation. Bimetallic systems (Ni-Co, Ni-Fe, and Co-Fe) with equal metal loadings (5 wt% each) showed better activity compared to their monometallic counterparts following the order: 5%Ni–5%Co/LaCeO₃ > 5%Ni–5%Fe/LaCeO₃ > 5%Co–5%Fe/LaCeO₃. The improved performance of the Ni-Co system is due to structural interactions between Ni and Co, which promote hydrogen desorption and accelerate N–H bond cleavage, while suppressing nitrogen recombination as the rate-limiting step. Further systematic optimization of the Ni/Co ratio showed that 8%Ni–2%Co/LaCeO₃ had the highest catalytic activity with consistent performance over 50 h. This optimal composition provides a balanced distribution of active metallic sites and moderate-to-strong basic sites, enhancing NH₃ adsorption and intermediate transformation. These findings show that LaCeO₃-supported Ni-Co catalysts are promising candidates for efficient hydrogen production from ammonia without using noble metals. Full article

Background/Objectives: Atrasentan is a selective endothelin A receptor antagonist (SERA) developed as a potential therapy for chronic renal diseases, including diabetic nephropathy and immunoglobulin A nephropathy. Despite this potential, understanding its metabolic bioactivation is essential for assessing the risks of drug-induced liver injury (DILI). However, the metabolic profile of atrasentan remains poorly characterized, and the mechanisms underlying its potential hepatotoxicity remain underexplored. Therefore, this study aims to investigate the metabolic pathways of atrasentan in human liver microsomes (HLMs) in the presence of nicotinamide adenine dinucleotide phosphate (NADP⁺), uridine diphosphate glucuronic acid (UDPGA), or glutathione (GSH). Methods: A liquid chromatography–high resolution mass spectrometry (LC-HRMS) coupled with a feature-based molecular networking approach was used to characterize metabolites. Characterization of the major metabolites was achieved through cytochrome P450 (P450) phenotyping with human recombinant P450 isoforms. Results: A total of eighteen metabolites were characterized through phase I and II metabolic reactions, including demethylenation, N-dealkylation, O-demethylation, hydroxylation, dehydrogenation, and glucuronidation. Atrasentan acyl glucuronide (M8) was confirmed as the predominant metabolite, and we also putatively annotated a catechol intermediate (M5) and its corresponding GSH conjugate (M15). Characterizing the GSH conjugate (M15) indicates that catechol intermediate (M5) can be further oxidized to a reactive ortho-quinone intermediate, which is subsequently trapped by GSH, suggesting the potential for a bioactivation mechanism. Reaction phenotyping demonstrated that the formation of M5 is catalyzed almost exclusively by the CYP3A subfamily. However, its direct translation to in vivo oxidative stress or covalent protein binding requires further studies. Conclusions: These findings demonstrate that feature-based molecular networking is a valuable strategy for metabolite characterization, underscoring the urgent need for further in vivo metabolism studies to definitively assess hepatotoxic risks associated with these reactive metabolites. Full article

In the renewable energy-driven “green electricity–green hydrogen–green ammonia” pathway, the development of low-temperature and low-energy-consumption ammonia synthesis technologies is of great significance. In this work, a plasma-catalytic ammonia synthesis system was established using a coaxial dielectric barrier discharge (DBD) reactor. The effects of different catalysts, including Ag, Cu, γ-Al₂O₃, BaTiO₃ and Co/BaTiO₃, Ni/BaTiO₃ on ammonia synthesis performance were systematically investigated. The reaction process was analyzed using voltage–current waveforms, Lissajous figures, and optical emission spectroscopy (OES). The results show that different catalytic systems have a significant influence on ammonia synthesis performance, with the promotional effect ranked as follows: Ni/BaTiO₃ > Co/BaTiO₃ > BaTiO₃ > Ag > γ-Al₂O₃ > Cu. Among them, Ni/BaTiO₃ exhibited the best performance. Under the conditions of N₂:H₂ = 1:1 and a gas flow rate of 2.5 L/min, the NH₃ synthesis rate reached 259.48 μmol/min, and the maximum energy efficiency reached 1.40 g-NH₃/kWh. Catalyst characterization results indicate that the BaTiO₃ support maintained a stable crystal structure, while the loaded metal species were highly dispersed and uniformly distributed on the support surface, which is beneficial for the adsorption and conversion of reactive species on the catalyst surface. Discharge characteristic analysis shows that the introduction of BaTiO₃ enhanced the local electric field and improved the uniformity of micro-discharges, while the further incorporation of metal active components strengthened the micro-discharge behavior. OES results reveal that the intensities of characteristic emission lines, such as NH, N₂⁺, and Hα, were significantly enhanced in the Ni/BaTiO₃ system, facilitating the formation and conversion of NH_x intermediates. The superior performance of Ni/BaTiO₃ is attributed to the coupling between BaTiO₃-induced dielectric enhancement and Ni-promoted surface hydrogenation and NH₃ desorption. This work provides mechanistic insight into catalyst-dependent DBD plasma-catalytic ammonia synthesis and offers an experimental basis for the further optimization of plasma-based ammonia production. Full article

Photocycloaddition reactions provide an efficient strategy for converting alkenes into structurally complex and high-value molecules that are often difficult to access under conventional thermal conditions. Herein, two readily accessible triarylamine-based imine molecular cages possessing distinct cavity environments were investigated as supramolecular photocatalysts for reactions of pyridinium-masked enol (PME) substrates with unactivated alkenes. Spectroscopic studies are consistent with the formation of electron donor–acceptor (EDA) interactions between the electron-rich cage frameworks and electron-deficient PME substrates. Upon blue-light irradiation (450 nm), these charge-transfer assemblies undergo photoinduced activation, likely involving single-electron transfer, N–O bond cleavage, and subsequent radical generation. The resulting radical intermediates participate in formal [4 + 2] cycloaddition reactions to afford tetralone derivatives under metal-free conditions. Comparative studies revealed that the two cages produce distinct product distributions and selectivities, suggesting that subtle variations in cage architecture and confined supramolecular environments influence the fate of reactive radical intermediates and the balance between productive cyclization and competing side pathways. While the detailed mechanistic origin of these effects remains unresolved, this work demonstrates the potential of covalent organic cages as structurally tunable platforms for modulating EDA-mediated photochemical reactivity and radical selectivity. Full article

Hydrogen peroxide (H₂O₂) is an important green oxidant, and developing efficient visible-light-driven routes for its synthesis is highly desirable. Herein, a CN/Zn_V-ZCS composite photocatalyst was constructed by coupling g-C₃N₄ (CN) with Zn-vacancy-containing ZnCdS (Zn_V-ZCS) for photocatalytic H₂O₂ production. The optimized CN/Zn_V-10 delivered 44.58 mmol g⁻¹ H₂O₂ within 60 min under 425 nm LED irradiation, outperforming pristine CN, ZCS, Zn_V-ZCS, and vacancy-free CN/ZCS, with good cycling stability. Trapping and EPR results identify O₂ as the key electron acceptor and ·O₂⁻ as an important intermediate. Structural characterization and XPS results indicate successful Zn-vacancy introduction, intimate heterointerface formation, and interfacial electron redistribution. Combined VB-XPS, photoelectrochemical, and reactive-species analyses suggest that Zn vacancies are favorable for O₂ adsorption/activation, whereas the CN/Zn_V-ZCS heterointerface promotes charge separation and migration. Based on the available evidence, a Z-scheme interfacial charge-transfer pathway is established in the CN/Zn_V-ZCS system. Full article

The commercialization of V-based catalysts for the selective catalytic reduction of NOx by NH₃ (NH₃-SCR) is hindered by their narrow operating temperature window, insufficient low-temperature (LT) activity, and severe SO₂-to-SO₃ oxidation. To bridge this gap, we herein introduced Nb and hexagonal BN into a VW/TiO₂ system to simultaneously enhance its LT SCR activity, suppress undesired side reactions, and improve durability. Nb incorporation promoted V⁵⁺/V⁴⁺ redox cycling and enhanced lattice oxygen mobility, thus reducing the apparent activation energy and suppressing SO₂ oxidation at elevated temperatures. However, excessive Nb loading induced NH₃ oxidation and N₂O formation. This drawback was mitigated by introducing BN as a dispersion promoter, which helped secure high catalytic performance at a reduced Nb content. The VWNb/Ti-BN catalyst achieved superior NOx conversion and N₂ selectivity over a wide temperature range and benefited from notably suppressed NH₃ oxidation and SO₂-to-SO₃ oxidation. Kinetic analysis revealed that Nb primarily lowered the reaction energy barrier via redox property enhancement, whereas BN accelerated surface reaction turnover by stabilizing and dispersing active acidic sites, markedly increasing the turnover frequency without reducing the activation energy. In situ spectroscopic analysis confirmed the accelerated consumption of adsorbed NH₃ species and enhanced formation of reactive NOx intermediates, indicating SCR pathway enhancement. After aging in the presence of SO₂ and H₂O, the best-performing honeycomb-type monolithic catalyst retained and NOx conversion of >80%, demonstrating excellent long-term durability under practical conditions. A composition-aware machine learning model based on log-ratio-transformed variables quantitatively identified the synergistic balance among V, Nb, W, BN, and TiO₂ as the dominant factor governing LT SCR performance. Thus, this work provides valuable mechanistic insights and a strategy for designing wide-temperature-window SCR catalysts with improved activity, selectivity, and resistance to sulfur poisoning. Full article

Noble metal-catalyzed C–H activation has transformed synthetic methodology by enabling direct modification of inert C–H bonds with high levels of efficiency, selectivity, and functional group tolerance. This mini-review provides a focused overview of the mechanistic foundations and emerging advances in C–H functionalization mediated by ruthenium, iridium, rhodium and palladium catalysts. Key activation modes including oxidative addition, concerted metalation deprotonation (CMD), and electrophilic pathways are discussed alongside the roles of high-valent intermediates and ligand control in determining reactivity and regioselectivity. Special emphasis is placed on recent electrochemical strategies, where anodic oxidation replaces traditional chemical oxidants, granting access to unique redox manifolds and expanding the scope of C–C, C–N, C–O, and C–X bond-forming reactions. Representative transformations highlight the versatility of noble metals in constructing heterocycles, enabling enantioselective processes, and facilitating late-stage functionalization of complex molecules. Current challenges and future perspectives are outlined, including the need for improved nondirected activation, deeper mechanistic insight, and enhanced scalability. Collectively, this review underscores the central role of noble metals in advancing sustainable and innovative C–H functionalization chemistry. Full article

Using norfloxacin (NOR) as the target pollutant, the synergism and degradation mechanism of ZnFe₂O₄-N-BC (MNBC), a nitrogen (N) and zinc ferrite (ZnFe₂O₄) co-doped biochar bifunctional catalyst (BC), in visible light (VIS)−peroxydisulfate (PDS) coupled system, were elucidated, and the synergistic mechanism was further supported by optical absorption and photo-induced charge transfer analyses. The results indicate that the degradation rate constant of the ZnFe₂O₄-N-BC/Vis-PDS system is 22.7 and 17.4 times higher than that of the ZnFe₂O₄-N-BC/Vis and ZnFe₂O₄-N-BC/PDS systems, respectively. More importantly, an apparent enhancement factor of 26.3% was obtained relative to the internal control systems. In addition, the coupled system showed a wider pH adaptation range. Furthermore, the radical quenching experiment and EPR analysis further revealed that multiple reactive species (including SO₄⁻, O₂⁻·, ·OH, h⁺, and ¹O₂) were involved in the degradation of NOR, and their relative contributions followed the order: ¹O₂ > SO₄⁻ > O₂⁻·> ·OH > h⁺. Finally, HPLC-MS analysis was performed to identify the key degradation intermediates of NOR, and thus to propose its possible transformation pathways. Full article