Search Results (6,358)

Pt–transition metal intermetallic compounds have been recognized as promising catalysts for oxygen reduction reaction (ORR). However, further enhancing the activity and durability of this kind of catalyst is still necessary. Herein, we report a novel L1₀-type PtFe intermetallic nanoalloy with the partial substitution of Fe sites by La as a highly active and stable catalyst towards ORR. This new intermetallic nanoalloy retains an ordered structure after the incorporation of La confirmed by XRD, XPS and TEM results and the ordered PtFe_0.5La_0.5 nanoparticles are embedded in porous carbon (L1₀-PtFe_0.5La_0.5@C) in very uniform particle size of around 2 nm. This L1₀-PtFe_0.5La_0.5@C catalyst exhibits a half-wave potential of 933 mV, which is about 12 mV and 70 mV higher than those of L1₀-PtFe@C and commercial Pt/C catalysts, respectively. Moreover, it also achieves an enhanced mass activity of 0.79 A mg_Pt⁻¹ at 0.90 V, which outperforms the performance of commercial Pt/C (0.10 A mg_Pt⁻¹). In addition, it also shows excellent stability with only 3 mV negative shift in half-wave potential after 20k CV cycles of accelerated durability testing. This high activity and stability may be attributed to the incorporation of La in the PtFe lattice, which induces the formation of a compressively strained Pt overlayer in acidic media which not only tunes the surface strain of Pt sites but also possesses robust resistance to the dissolution of Fe and La. This work also provides a new direction for the development of Pt-based intermetallic catalysts for efficient catalysis applications. Full article

Constructed wetlands (CWs) are a low-energy alternative for treating dye-containing wastewater; however, the mechanisms enabling azo dye removal without external carbon supplementation remain unclear. This study demonstrates that azo dye reduction can proceed under oxic bulk conditions in CWs through vegetation-induced microscale redox heterogeneity. Lab-scale CWs planted with cattail and papyrus were evaluated for the removal of Reactive Orange 16 (RO16, monoazo) and Reactive Black 5 (RB5, diazo) at influent concentrations of 10–50 mg/L under varying ambient temperature (2–36 °C) and hydraulic retention time (1–15 days). Vegetated CWs consistently outperformed the unplanted system, achieving 60–95% removal for RO16 and up to 98% removal for RB5, whereas the unplanted CW showed substantially inferior performance, with removal efficiencies below 54% for RO16 and below 37% for RB5. Dye-decolorizing bacteria, including Priestia megaterium and Clostridium spp., were isolated exclusively under anaerobic conditions from vegetated CWs despite oxic bulk dissolved oxygen levels. The isolates did not decolorize dyes under aerobic conditions or when dyes were provided as sole carbon sources, indicating that azo dyes functioned as electron acceptors and required additional electron donors. These results suggest that vegetation promotes localized reductive microenvironments and supplies endogenous organic carbon, enabling anaerobic azo bond reduction within otherwise oxic systems. The findings indicate a mechanistic basis for plant–microbe interactions in CWs and support the design of sustainable treatment systems for dye-containing wastewater without external carbon input, particularly in warm regions. This study resolves a long-standing question of how azo dye reduction proceeds in CWs without external carbon input. Full article

Freshwater scarcity is a major global issue faced by various regions, and the most common portable water sources globally are estuaries, canals, dams, lakes, and rivers. Existing water resources function as the best sinks for the frequent release of effluents from industrial and residential activities. This common practice often results in water pollution, a deterioration in marine biodiversity, and possible health risks for human populations. This study employed standard analytical methods in assessing the physicochemical and microbial characteristics of water samples collected from the Sundays River estuary in Eastern Cape Province (ECP), South Africa (SA). Microbiological assessment revealed that during the spring season, presumptive Escherichia coli (E. coli) colony counts were 1 cfu/100 mL, while total coliforms (TCs) and fecal coliforms (FCs) were recorded at 42.67 cfu/100 mL and 1 cfu/100 mL, respectively. In the summer season, fecal coliform (FC) counts reached 3.5 cfu/100 mL, while Enterococcus levels were higher, ranging up to 77.75 cfu/100 mL. Furthermore, the average standards of physicochemical parameters assessed in water obtained from both spring and summer seasons ranged as follows: pH (8.71–9.31), temperature (20.98–22.21 °C), turbidity (10–35.55 FNU), total alkalinity (22.25–94.00 mg/L), oxidation–reduction potential (ORP) (8.05–151.6 mV), electrical conductivity (EC) (13,915–40,260 uS/cm), salinity (8.07–25.78 psu), dissolved oxygen (DO) (6.79–7.39 mg/L), total dissolved solids (TDSs) (6960.6–20,125 mg/L), and biochemical oxygen demand (BOD) (0.11–2.94 mg/L). The levels of TDS, EC, turbidity, and salinity in the Sundays River estuary water exceeded the World Health Organization (WHO) guidelines of 2017, rendering the water unfit for even recreational purposes. Additionally, the bacterial levels identified in this study were above the values set by the South Africa Department of Water Affairs (SA-DWAF). The identified microorganisms are perceived as essential indicators of fecal contamination and have the potential to multiply in the environment. Possible pollution may be a result of various municipal effluents consistently discharged into the waterbody. Full article

Monolithic ceramic catalysts are a key technology for the industrial treatment of coal mine ventilation air methane (VAM). The preparation of straight-channel NiO/CeO₂ monolithic ceramic catalysts via phase inversion addresses critical bottlenecks for industrial VAM abatement. However, high-temperature sintering leads to irreversible NiO agglomeration and coarsening, severely reducing catalytic activity. In this study, an in situ reduction–oxidation reconstruction method is developed to regenerate sinter-degraded NiO. The reconstructed catalyst increases methane conversion from below 70% after sintering to over 95% at 550 °C and achieves full conversion at 600 °C. The catalyst maintains near 100% conversion during 400 h of continuous operation at 600 °C and shows no performance degradation over 15 thermal cycles. Moreover, the reconstructed catalyst exhibits excellent steam tolerance with fully reversible deactivation. The reconstructed catalyst presents a refined porous structure with BET surface area rising from 4.5 to 11.4 m² g⁻¹, an elevated Ni³⁺/Ni²⁺ ratio (1.47 to 1.97), a higher surface adsorbed oxygen proportion (36.8% to 48.7%) and significantly strengthened NiO-CeO₂ interfacial interaction. This work provides a facile and efficient in situ regeneration strategy, greatly enhancing the VAM oxidation activity and stability of sinter-degraded monolithic ceramic catalysts. Full article

Although bio-hydrogenated diesel (BHD) offers drop-in compatibility and high oxidative stability, its poor lubricity remains a critical barrier to long-term engine deployment. Previous studies have primarily relied on short-term tribological assessments, leaving insufficient empirical data on sustained wear behavior under realistic conditions. This study addresses that gap through a 200 h durability evaluation of BHD–biodiesel blends in a single-cylinder diesel engine under constant load conditions per Thai Industrial Standard TIS 2618-2557. Five fuels, namely diesel, pure BHD, BHD90, BHD70, and pure biodiesel, were tested to identify the critical biodiesel threshold for optimal tribological and oxidative performance. BHD90 (90% BHD + 10% biodiesel) emerged as the optimal formulation, delivering the lowest torque reduction (11.2%) and minimal iron wear particles (101 ppm), while preserving oxidation stability. Biodiesel concentrations exceeding 10% induced accelerated lubricant oxidation through hygroscopic effects, negating the lubricity benefits. Fourier-transform infrared spectroscopy (FTIR) analysis of piston carbon deposits further revealed that higher biodiesel blends produced more oxygenated compounds, whereas pure BHD and diesel generated predominantly aliphatic hydrocarbons. These findings establish a mechanistic relationship between fuel composition, oxidation, and wear under endurance conditions, providing a practical guideline for renewable diesel formulation that balances lubrication performance, oxidation control, and long-term engine durability. Full article

Salt stress represents a significant abiotic stress factor that adversely affects plant growth and development. It directly inhibits both vegetative and reproductive growth, resulting in substantial reductions in crop yield and quality. Consequently, the identification of salt tolerance genes and the elucidation of their underlying molecular mechanisms are crucial for improving crop salt tolerance and ensuring agricultural productivity. To investigate the molecular basis underlying differential salt tolerance between Zheng58 and PH4CV, we employed pooled sequencing (BSA-seq) using extreme phenotypic individuals from their F₂ population and conducted a comparative transcriptome analysis at the seedling stage of the two genotypes. Phenotypic, physiological, biochemical, and ion content analyses revealed that Zheng58 exhibited significantly superior performance compared to PH4CV under salt stress conditions. BSA-seq analysis identified six genomic regions associated with salt tolerance, encompassing a total of 391 genes. Functional annotation enabled the screening of 151 candidate genes potentially involved in salt stress responses. Transcriptome profiling indicated that differentially expressed genes were significantly enriched in biological processes, particularly plant hormone signal transduction and MAPK signaling pathways. Integrating BSA-seq and transcriptome data, key candidate gene ZmACC2 (Zm00001eb419400) was identified as potentially involved in the regulation of salt tolerance in maize. This gene may modulate Na⁺/K⁺/Ca²⁺ homeostasis and reactive oxygen species metabolism through defense responses mediated by ethylene (ETH) and hydrogen peroxide, as well as through ion homeostasis regulatory pathways. This study provides valuable candidate genes and a theoretical foundation for further dissection of the molecular mechanisms governing salt tolerance in maize. Full article

Background: Post-cardiac arrest syndrome (PCAS) following out-of-hospital cardiac arrest (OHCA) is driven by global ischemia–reperfusion injury, endothelial dysfunction, and a dysregulated inflammatory response. This cascade frequently culminates in profound vasoplegia and multiorgan failure, even when guideline-directed post-resuscitation management is applied. Hemoadsorption using the CytoSorb device may attenuate hyperinflammation and vasoplegia by removing circulating inflammatory and injury-related mediators. Methods: This single-centre, retrospective cohort study compared adults with PCAS following OHCA who received hemoadsorption with propensity score-matched controls (1:1 matching; n = 50 per group). For patients treated with hemoadsorption, data were analyzed within predefined intervals covering the 24 h preceding therapy initiation (T1) and the 24 h following the completion of the hemoadsorption treatment period (T2). Controls were evaluated at time points aligned to those of their matched hemoadsorption counterparts. Hemodynamic, metabolic, respiratory, and organ injury markers were assessed. Results: Formal between-group comparisons of temporal change between T1 and T2 showed no statistically significant differences between hemoadsorption-treated patients and matched controls across key parameters, including VIS (Δ −18.7 vs. −7.7; p = 0.183) and lactate (Δ −1.8 vs. −1.25 mmol/L; p = 0.780), as well as markers of organ injury, pH, and oxygenation. In exploratory ANCOVA models, only base excess was associated with treatment group (p = 0.035). Survival to hospital discharge was comparable (48% vs. 40%; p = 0.423), with similar neurological outcomes. Within the hemoadsorption group, pre–post comparisons around hemoadsorption initiation (T1–T2) demonstrated marked improvements, including reduced vasoactive support (VIS 70.0 to 12.1; p = 0.039), substantial lactate clearance (4.1 to 1.1 mmol/L; p < 0.001), and declines in organ injury markers (AST, ALT, LDH, myoglobin), alongside more pronounced platelet reduction compared with controls (129 to 57 × 10³/µL vs. 189 to 123 × 10³/µL). However, adjusted analyses indicated that these changes were primarily driven by baseline shock severity rather than a treatment-specific effect. Conclusions: In this propensity score-matched cohort of PCAS patients after OHCA, hemoadsorption was associated with within-group physiological changes but showed no detectable advantage over matched controls, with similar survival. These findings are hypothesis-generating and warrant prospective studies with standardized timing and phenotype-guided patient selection. Full article

This study evaluates the technical feasibility of deploying containerized oxy-combustion power modules with integrated CO₂ capture in remote Ecuadorian Amazon oil fields. Associated petroleum gas is conditioned with a 35 wt.% diethanolamine (DEA) sweetening stage specifically implemented to remove H₂S and reduce acid-gas loading prior to combustion, improving fuel quality and protecting downstream equipment while increasing methane mole fraction for combustion. System efficiency is governed by stoichiometric oxygen demand, with methane requiring 2 mol O₂/mol fuel and hexane requiring 11 mol O₂/mol fuel; favoring methane-rich streams reduces ASU energy demand, enhances combustion performance, and lowers separation costs. The combined oxy-combustion cycle attains a thermal efficiency of 33.10% and an exergetic efficiency of 39.98%. Major energy penalties arise from the cryogenic air separation unit and the CCS train, yet operational tuning of CO₂ recirculation and steam flow could raise thermal efficiency by up to 2%. The ASU produces oxygen at 96.67% purity with an energy consumption of 0.385 kWh/kg O₂, while the CCS achieves 99.99% CO₂ capture at 0.41 kWh/kg CO₂. Sourcing gas from three production blocks provides flexibility to accommodate supply variability. The modular 272 MW unit demonstrates viability for off-grid power supply, routine flaring reduction, and scalable acid-gas valorization in frontier oilfields. Full article

Microplastics (MPs) in wastewater treatment plants are predominantly retained in sewage sludge, making sludge processing a critical stage for MP transformation and potential pollutant release. However, the aging of polyethylene (PE) MPs and the release of MP-derived dissolved organic matter (MP-DOM) during sludge dewatering remain poorly understood. In this study, representative sludge conditioners were set up in dewatering experiments to investigate the changes in PE MP surface properties, pollutant-carrying potential, and MP-DOM release behavior. The results showed that sludge dewatering induced pronounced surface aging of PE MPs, including wrinkling, cracking, particle fragmentation, and the formation of polar oxygen-containing functional groups. These changes significantly increased the Cd adsorption potential of PE MPs, reaching 8228 ± 568 mg kg⁻¹. Lime conditioning promoted stronger fragmentation and a greater reduction in particle size than other conditionings, which likely increased the specific surface area. Meanwhile, a substantial release of PE MP-DOM was observed, with dissolved organic carbon concentrations in sludge process water being 2–30 times higher than those in deionized water. Fluorescence and molecular analyses showed that PE MP-DOM was dominated by protein-like and fulvic-like substances and also contained phthalates, fatty acids, and acetamide-based plasticizers. The magnitude and composition of PE MP-DOM release were strongly regulated by conditioner-induced pH and ionic strength. Alkaline conditions and increasing concentrations of Ca²⁺ (0.1–2.1 mol L⁻¹) and Fe³⁺ (0.006–0.6 mol L⁻¹) enhanced PE MP additive release. These findings demonstrate that sludge dewatering is an active process that accelerates PE MP aging and associated organic release. This work provides new insight into the environmental behavior of MPs during sludge treatment and offers a basis for developing sustainable sludge management. Full article

Phase formation characteristics during the thermochemical reduction of metals from natural coltan using aluminum and calcium–aluminum alloy at 1400–1450 °C were investigated to develop methods for extracting niobium and tantalum from rare metal raw materials. The studied coltan sample consists of a columbite–tantalite solid solution with the composition (Mn,Fe)(Nb,Ta)₂O₆, cassiterite Sn_0.9O₂, tapiolite (Ta,Nb)₂(Mn,Fe)O₆, and calcioolivine Ca₂SiO₄. This study established that the choice of reducing agent determines the sequence of oxide phase transformations. During the aluminothermic process, orthorhombic columbite–tantalite is completely reduced, while tetragonal tapiolite persists even at 1400 °C. The use of a calcium–aluminum alloy containing 69.4 wt.% Ca results in a reversal of this trend: tapiolite is reduced at the early stages (800–1250 °C) through an intermediate (Ta,Nb)O₂ phase, whereas the columbite–tantalite solid solution remains up to 1250 °C. Calcium, having a high affinity for oxygen, forms intermediate perovskite-type oxide phases that act as diffusion barriers, limiting the access of the reducing agent to residual mineral inclusions (mainly Nb-Ta minerals of the orthorhombic crystal system). A temperature rise to 1450 °C initiates the redistribution of oxide components: the content of CaNbO₃ decreases, the Ca₂(Nb,Ta)AlO₆ phase disappears, and its components are involved in the formation of Ca(Nb,Ta)_0.25MnO_2.74 and Ca₄Nb₂O₉. Diffusion constraints are reduced, and the residual columbite–tantalite solid solution is reduced, as confirmed by its complete absence in the products at 1450 °C. In the metallic phase, solid solutions of tantalum and niobium, Ta-Nb-Sn intermetallic compounds (Ta,Nb)₃Sn, titanium aluminide, and ferroalloys with an increased (Ta,Nb)/(Fe,Mn) ratio are formed. The phase transformations elucidated during metallothermic reduction of coltan using different reducing agents, together with the formation of metallic and intermetallic phases, establish a scientific foundation for the development of advanced rare metal extraction processes. Full article

Human adipose biology is strongly influenced by three-dimensional (3D) architecture, cell–cell interactions, and local oxygen availability maintained over a long-term culture period, features that are not reproduced in traditional two-dimensional (2D) culture systems. To address this gap, we established a long-term human adipose-derived stem cell (hASC) spheroid model using elastin-like polypeptide–polyethyleneimine (ELP-PEI) coating. The ELP-PEI coating facilitated stable spheroid formation and sustained adipogenic differentiation over 56 days. As spheroids enlarged and matured, they exhibited hallmark features of adipocytes, including lipid accumulation, morphological compaction, and transition out of the proliferative state. Glucose uptake increased during maturation and declined as spheroids became larger. This reduction coincided with a marked rise in hypoxia-inducible factor-1α (HIF-1α) expression, indicating the emergence of a hypoxic microenvironment within larger spheroids. Notably, inhibiting HIF-1α restored insulin-stimulated glucose uptake, demonstrating that hypoxia was the primary driver of impaired insulin responsiveness in late-stage spheroids. These findings position ELP-PEI-supported hASC spheroids as a practical and physiologically relevant platform for studying human adipocyte biology, particularly the development and reversibility of hypoxia-associated metabolic dysfunction. This model offers new opportunities for mechanistic studies and for evaluating therapeutic strategies targeting insulin resistance and adipose tissue pathology. Full article

Hydrogen-based reduction of manganese ores has attracted increasing attention as a promising route for low-carbon manganese production. In this study, the reduction behavior, microstructural evolution, and kinetics of a high-barium-rich manganese ore were investigated in both dried and calcined states under isothermal hydrogen atmospheres at 600–800 °C. The ore was characterized using XRF, XRD, optical microscopy, SEM-EDS, and porosity measurements to evaluate mineralogical and structural changes during calcination and reduction. Calcination at 900 °C transformed MnO₂ into Mn₂O₃/Mn₃O₄, removed volatile components, and generated micro-porosity that improved gas accessibility. Isothermal reduction experiments revealed a rapid initial reduction stage followed by a slower reaction regime, with increasing temperature significantly accelerating the reduction rate. Despite isothermal furnace conditions, a temporary rise in sample temperature was observed due to the exothermic nature of manganese oxide reduction by hydrogen. XRD analysis confirmed that manganese oxides were predominantly reduced to MnO, while iron oxides were converted to metallic Fe. Porosity measurements showed significant pore development during reduction at moderate temperatures due to oxygen removal and gas evolution; however, at higher temperatures, partial sintering led to pore coalescence and densification, reducing the overall porosity. Kinetic analysis showed that the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model effectively describes the reduction behavior. The apparent activation energies were 21.92 kJ.mol⁻¹ for dried ore and 17.40 kJ.mol⁻¹ for calcined ore, indicating diffusion-influenced kinetics. The results demonstrate that calcination enhances hydrogen reducibility by improving gas accessibility and reducing kinetic resistance, highlighting its importance for hydrogen-based manganese pre-reduction processes. Full article

CeO₂ is widely studied in catalysis owing to its Ce⁴⁺/Ce³⁺ redox couple and oxygen storage capacity (OSC), but its low-temperature redox activity remains a challenge. To address this, this study investigates the effects of saturated In³⁺ doping (1 mol.%) on the structural, redox, and catalytic properties of nano-octahedral CeO₂. Structural and chemical analyses reveal that In³⁺ doping induces lattice contraction from 5.4171 to 5.4129 Å, increases oxygen vacancy concentration from 29.7% to 39.8%, and raises surface Ce³⁺ fraction from 27.6% to 30.0%. Consequently, H₂-TPR measurements show that the surface reduction peak temperature decreases from 548 to 406 °C and the onset reduction temperature shifts from 309 °C to 183 °C. Quantitative OSC analysis further demonstrates that the low-temperature OSC increases from 13.17 to 20.57 mmol O₂/mol and the high-temperature OSC from 53.36 to 59.38 mmol O₂/mol upon doping. As a result of these enhancements, CO-TPSR tests reveal improved low-temperature CO oxidation performance, with the CO₂ light-off temperature decreasing from 99 to 72 °C and the rapid oxidation temperature from 153 to 96 °C. Notably, H₂O and H₂ signals are detected during CO-TPSR, and FTIR analysis confirms the enrichment of surface hydroxyl groups in the doped sample, offering new mechanistic insights into the involvement of surface species in the reaction pathway. Overall, saturated In³⁺ doping effectively enhances the oxygen vacancy concentration, surface reducibility, and CO oxidation activity of nano-octahedral CeO₂. Full article

Two-dimensional Ti₃C₂O₂ MXene has emerged as a promising electrode material for non-enzymatic glucose sensing due to its metallic conductivity and biocompatibility. However, the atomic-scale sensing mechanism remains unclear. This DFT study uses the PBE functional with the D3(BJ) dispersion correction to elucidate glucose–MXene interactions under idealized vacuum conditions. Pristine Ti₃C₂O₂ shows metallic behavior with a density of states of about 8.2 states per electron volt at the Fermi level, dominated by Ti 3d states. β-d-glucose adsorbs onto the surface through hydrogen bonding, with an adsorption energy of −0.82 eV at a separation distance of 2.8 angstroms. Bader analysis indicates a transfer of about 0.15 electrons from MXene to glucose, resulting in a Fermi level shift of about −0.15 eV and an 18% reduction in the density of states at the Fermi level. These changes correspond to an estimated sensitivity of approximately 0.6 μA mM⁻¹ cm⁻² and a detection limit of about 17 µM, consistent with reported experimental performance of MXene-based sensors. Comparative adsorption calculations for common sweat interferents yield −0.45 eV for lactate and −0.25 eV for urea, indicating weaker interfacial affinity than glucose; these values reflect thermodynamic binding strength and possible surface occupation rather than definitive electrochemical selectivity, which additionally depends on redox potential, electron-transfer kinetics, and operating bias. We acknowledge three main limitations: first, the model considers only pure oxygen termination rather than mixed oxygen, hydroxyl, and fluorine terminations; second, the calculations are performed under vacuum rather than in aqueous conditions; third, the study is based on static zero kelvin structures rather than finite temperature dynamics. Despite these idealizations, the results provide baseline mechanistic insights to support rational design of MXene-based glucose sensors. Full article

Background: Oral biofilms are a major etiological factor in dental caries, periodontal disease, peri-implantitis, and endodontic infections. Increasing antimicrobial resistance and the limitations of conventional therapies have intensified interest in antimicrobial photodynamic therapy (aPDT). Hypericin, a natural photosensitizer derived from Hypericum perforatum, demonstrates potent reactive oxygen species generation and broad antimicrobial activity; however, its dental applications remain insufficiently synthesized. Objective: To systematically evaluate the antimicrobial efficacy, treatment parameters, safety, and clinical potential of hypericin-mediated aPDT against oral biofilms and infections in dentistry. Methods: This systematic review was conducted according to PRISMA 2020 and registered in PROSPERO CRD42024617727. Electronic searches of PubMed/MEDLINE, Embase, Scopus, and the Cochrane Library (January 2010 to December 2025) were performed. Studies assessing hypericin-mediated aPDT in oral or dental contexts were included. Methodological quality was evaluated using a predefined nine-domain risk-of-bias tool. Results: Eleven studies met the inclusion criteria. Hypericin-mediated aPDT demonstrated strong antimicrobial effects, achieving up to 99% planktonic inactivation and significant biofilm reduction across bacterial and fungal species. Activity was particularly pronounced against Gram-positive organisms, including Staphylococcus aureus and Enterococcus faecalis. However, efficacy against mature biofilms was variable and often dependent on formulation and irradiation parameters. Most studies showed moderate methodological quality, with frequent deficiencies in reporting light calibration and dosimetry. Advanced delivery systems, including liposomal and nanoparticle formulations, improved photodynamic performance. Conclusions: Hypericin-mediated aPDT shows promising antimicrobial activity against oral pathogens and biofilms, with favorable selectivity and safety profiles. Nevertheless, the evidence remains predominantly preclinical and heterogeneous. Standardized protocols and well-designed clinical trials are required before routine dental implementation can be recommended. Full article