Search Results (1,117)

The sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline media remain a primary bottleneck for anion exchange membrane fuel cells (AEMFCs), necessitating catalysts that synergistically optimize the adsorption of hydrogen (*H) and hydroxide (*OH) intermediates. Herein, we construct a well-defined heterointerface between Pd clusters and CeO₂ on nitrogen-doped carbon (Pd-CeO₂/NC) to electronically engineer the active sites. Spectroscopic studies and theoretical calculations collectively reveal that CeO₂ acts as an electron acceptor, drawing electrons from Pd via interfacial Pd-O-Ce bridges. This charge transfer induces a downshift of the Pd d-band center, which optimally tunes the adsorption strength of both *H and *OH at the interface, thereby breaking the scaling relationship that limits HOR activity. The resulting Pd-CeO₂/NC catalyst achieves an exceptional exchange current density of 3.66 mA cm⁻², surpassing that of commercial Pt/C by a factor of two and ranking among the best reported noble metal catalysts. Furthermore, it exhibits outstanding long-term stability and remarkable CO tolerance, retaining high activity in an atmosphere containing 1000 ppm CO. This work underscores the profound efficacy of metal–oxide heterointerface engineering in regulating electronic structures for multi-intermediate optimization, offering a viable design principle for advanced alkaline HOR electrocatalysts. Full article

The transport sector is a major contributor to urban air pollution and greenhouse gas emissions in Pakistan, posing significant challenges to sustainable development and climate commitments. This study develops the first technology-resolved, high-resolution, multi-pollutant emission inventory and scenario analysis for Pakistan’s transport sector, addressing key gaps in previous studies that lacked integrated multi-pollutant assessments, comprehensive coverage of non-road sources, and long-term scenario comparisons. The analysis integrates road and non-road transport sources within the Greenhouse Gas–Air Pollution Interactions and Synergies (GAINS) modeling framework. Emissions are projected for 2024–2050 under a business-as-usual (BAU) scenario and three mitigation pathways: an Electric Vehicle Transition (EVT) emphasizing transport electrification, a Euro-VI scenario focusing on stringent fuel and vehicle emission standards, and an integrated nationally determined contribution strategy (NDC+) scenario combining electrification, regulatory improvements, and structural transport reforms. In 2024, transport-related emissions are estimated at approximately 22 kt of fine particulate matter (PM_2.5), over 300 kt of nitrogen oxides (NO_x), and nearly 39 Mt of carbon dioxide (CO₂), alongside substantial emissions of other gaseous pollutants and short-lived climate forcers. By 2050, the NDC+ scenario achieves the largest reductions relative to business-as-usual, demonstrating that coordinated electrification and emission control strategies can simultaneously reduce air pollution and greenhouse gas emissions. The results demonstrate strong synergies between climate mitigation and air quality improvement, showing that integrated strategies combining electrification with stringent emission standards can simultaneously reduce greenhouse gas emissions and major air pollutants while advancing cleaner and more sustainable mobility. This analysis provides a consistent and policy-relevant evidence base derived from best-available data and modeling tools to support Pakistan’s NDC implementation, sustainable mobility planning, and integrated air quality and climate strategies, with lessons transferable to other rapidly developing economies. Full article

The efficiency of hydrogen production via water electrolysis is severely constrained by the sluggish reaction kinetics of the oxygen evolution reaction (OER). Herein, we constructed a nitrogen-doped CoFe Prussian blue analog (CoFePBA-N) electrocatalyst with a nanosheet-assembled cubic architecture by plasma. Plasma treatment induces morphological reconstruction and introduces nitrogen dopants and abundant vacancies, which not only increase the number of exposed active sites but also modulate the electronic structure of Co/Fe centers. Consequently, the optimized CoFePBA-N catalyst achieves a current density of 500 mA cm⁻² at low overpotentials of 322, 344, and 374 mV in alkaline freshwater, alkaline simulated seawater, and alkaline natural seawater, respectively. Furthermore, the catalyst maintains stable operation for over 300 h in alkaline freshwater and nearly 270 h in alkaline natural seawater, exhibiting exceptional durability. The enhanced catalytic performance is attributed to the synergistic effects of nitrogen doping, vacancies, and improved charge-transfer capability. This study provides an effective approach for modulating the electronic structure of Prussian blue analogs, thereby enabling efficient alkaline water and seawater electrolysis. Full article

Campylobacter jejuni is a major zoonotic pathogen that circulates among birds, livestock, humans, and environmental reservoirs, yet the genomic mechanisms that enable persistence and transmission across divergent hosts remain incompletely understood. Here, we sequenced 61 C. jejuni isolates recovered from multiple host-associated sources in Shenzhen, China, from 2016 to 2023, and analyzed them together with 312 dereplicated publicly available high-quality reference genomes. Phylogenomic analyses resolved three major clades, including one avian-restricted clade and two clades showing frequent cross-host occurrence. Human-associated isolates displayed lower coding density than mammal-associated isolates and significantly higher proteome-level carbon and nitrogen demands than avian-associated isolates. Comparative genomic analyses further revealed strong host-associated divergence in chromosome-encoded, plasmid-encoded, and horizontally acquired gene repertoires. In human-derived isolates, 11 dataset-specific human-unique KEGG genes and 48 human-unique virulence-associated genes were identified, and human-associated strains showed the strongest multidrug-resistance signal across both chromosome-encoded and mobile-gene compartments. Resistance-associated functions enriched in human-associated genomes included antibiotic inactivation, efflux-mediated resistance, target protection/replacement/alteration, reduced permeability, and nutrient-acquisition-associated resistance. By contrast, core host-interaction loci remained under strong purifying selection, indicating that major human-associated traits were linked more closely to mobile gene acquisition than to extensive mutation-driven diversification. Together, these findings support a proposed genome-partition framework of host adaptation in C. jejuni, in which relatively stable chromosomal backgrounds are complemented by rapid plasmid- and horizontal-transfer-mediated acquisition of high-impact accessory genes. Full article

The spontaneous reduction of one Cu(II) center to Cu(I) in a series of three dinuclear copper complexes in acetonitrile is described. These complexes feature ligands that include nitrogen donors from a diazecine ring and imidazole, designated as promeim, thiopromeim, and thioenmeim; the latter two incorporate a thioether as a third donor component. The mechanism of metal reduction was elucidated through spectroscopic and spectrometric techniques (UV-vis, EPR, XANES, ESI-MS) and electrochemical tools, in combination with DFT electronic structure calculations. Based on these and on spectroelectrochemical results, a mechanism is proposed in which the one-electron reduction of one of the copper ions is achieved by a one-electron oxidation in the adjacent imidazole group, while the other copper ion remains as Cu(II). The persistent detection of superoxide and peroxide over long periods suggests a mechanism in which a catalytic cycle involving electron transfer occurs between copper, ligand, and dioxygen. Full article

The development of reliable electrochemical interfaces for biosensor applications requires materials that combine high conductivity, large effective surface area, and suitable platforms for biomolecule immobilization. In this work, a hybrid electrochemical platform based on screen-printed carbon electrodes (SPCEs) modified with electropolymerized polypyrrole (PPy) and electrodeposited silver particles (AgPs) is presented for the subsequent immobilization of Ki-67 antibodies. PPy films were synthesized under optimized electrochemical conditions, producing homogeneous, porous, and electrochemically stable coatings that significantly enhanced the doping/undoping processes from 0.3280 C/0.3284 C to 0.3281 C/0.3284 C for SPCE and SPCE-PPy, respectively. Subsequently, silver particles were deposited onto the PPy matrix, resulting in a well-dispersed and uniform distribution of AgPs, promoted by the interaction between Ag⁰ and the nitrogen groups in the polymer backbone. The synergistic combination of PPy and AgPs resulted in improved charge-transfer properties and enhanced electrochemical reversibility, thereby decreasing the peak-to-peak separation of the ferricyanide/ferrocyanide redox couple used as a probe by 40%. Immobilization of Ki-67 antibodies was achieved via direct interaction with AgPs, resulting in a marked passivation effect, as evidenced by the suppression of redox probe signals, confirming successful biofunctionalization. The proposed SPCE-PPy-AgP architecture provides a robust, reproducible, and versatile platform for antibody immobilization, as demonstrated by oxidation and reduction peaks with relative standard deviations (RSDs) of 3.18% and 4.43%, respectively, highlighting its potential for developing label-free electrochemical immunosensors for clinically relevant proliferation biomarkers. Full article

Humic substances (HS), derived from the degradation of organic matter in terrestrial and aquatic systems, play critical roles in nutrient cycling, metal complexation, and soil fertility. This study investigates whether HS derived from Greek peaty lignite (leonardite) can bind Mo(VI), an essential micronutrient for nitrogen fixation and assimilation processes. Titration experiments showed that the addition of Mo(VI) to HS solutions decreased pH, indicating Mo(VI)–HS complexation via proton-release reactions. UV-Vis spectra revealed charge-transfer interactions without evidence of Mo reduction, while FTIR analysis confirmed that carboxylic, phenolic, and alcoholic groups participate in Mo(VI)–HS association as indicated by shifts in COO–, C=O, and O–H vibrations. The results demonstrate that HS can effectively complex Mo(VI), increasing its solubility and potentially enhancing its bioavailability in soils. These findings highlight the value of humic-rich materials such as leonardite in sustainable crop nutrition. Full article

Satellite remote sensing has become essential for water quality assessment across inland and coastal environments, with rapid improvements in recent years. Significant advances have been made in detecting optically active parameters (such as chlorophyll-a, suspended matter, and turbidity), showing consistently strong performance across multiple studies. Specifically, the median validation performance (R²) derived from the quantitative synthesis indicates R² = 0.82 for chlorophyll-a (interquartile range—IQR: 0.75–0.90), R² = 0.80 for total suspended matter (IQR: 0.78–0.85), and R² = 0.88 for turbidity (IQR: 0.85–0.90). Conversely, the retrieval of optically inactive parameters (such as nutrients like total phosphorus and total nitrogen) remains more context dependent. It exhibits moderate, more variable results, with median R² = 0.68 (IQR: 0.64–0.74) for total phosphorus and R² = 0.75 (IQR: 0.70–0.80) for total nitrogen. These findings clearly illustrate the varying success of retrievals of optically active and inactive parameters and underscore the inherent difficulties of indirect estimation methods. However, high reported accuracy has yet to translate into transferable, uncertainty-informed, and operational monitoring systems. This gap stems from structural issues in validation design, physics integration, uncertainty management, and multi-sensor compatibility rather than data limitations alone. We present a PRISMA-guided, distribution-aware quantitative synthesis of 152 peer-reviewed studies (1980–2025), based on a systematic search protocol, to evaluate satellite-based retrievals of both optically active and inactive parameters. Instead of simply averaging performance, we analyse the empirical distributions of validation metrics, considering the validation protocol, sensor type, parameter category, degree of physics integration, and uncertainty quantification. The synthesis demonstrates that validation strategy often influences reported results more than the algorithm class itself, with accuracy inflated under non-independent cross-validation methods and notable variability between studies concealed by mean-based reports. Across four decades, four persistent structural challenges remain: limited transferability across sites and sensors beyond calibration areas; weak or implicit physical integration in many data-driven models; lack of or inconsistency in uncertainty quantification; and fragmented multi-sensor harmonisation that restricts operational scalability. To address these issues, we introduce two evidence-based coding frameworks: a physics-integration taxonomy (P0–P4) and an uncertainty-quantification hierarchy (U0–U4). Applying these frameworks shows that most studies remain focused on low-to-moderate levels of physics integration and primarily consider uncertainty at the prediction stage, with limited attention to upstream sources throughout the observation and inference process. Building on this structured synthesis, we propose a transferable, physics-informed, and uncertainty-aware conceptual framework that links model architecture, validation robustness, and probabilistic uncertainty to well-founded design principles. By shifting satellite water quality modelling from isolated algorithm demonstrations towards integrated, evidence-based system design, this study promotes scalable, decision-grade environmental monitoring amid the accelerating impacts of climate change. Full article

Heating gases to high temperatures is essential for supplying energy to thermal and thermochemical processes. This study presents the optical–thermal design of a mini heliostat field coupled with a tubular solar receiver equipped with second optics, aiming to heat nitrogen to approximately 850 K. The secondary optical system redistributed up to 40% of the incident solar flux from the front to the rear surface of the receiver, improving radial temperature uniformity and significantly reducing thermal gradients along the tube wall. An overall optical efficiency of 65.25% was achieved, accounting for atmospheric attenuation, shading, blocking, and the cosine effect. A coupled computational model was developed by solving the conservation equations of mass, momentum, and energy, with the spatially resolved solar flux distribution obtained via ray tracing used as a thermal boundary condition. The simulation results, validated with an empirical correlation, include solar flux contours, nitrogen temperature distributions, surface temperatures, and heat transfer coefficients. The configuration with a 12 mm vertex spacing between secondary reflectors demonstrated the best thermal performance, reducing the maximum tube surface temperature by 11% and improving radial symmetry, while maintaining nitrogen outlet temperatures near the design target of 850 K. These results confirm the suitability of the system for high-temperature applications such as solar pyrolysis using nitrogen as the heat transfer fluid to deliver the required thermal energy. Full article

The objective of this study was to design and evaluate π-extended 1,8-naphthalimide derivatives as photoinduced electron transfer (PET) optical sensors for protons and metal cations, with emphasis on the role of heterocyclic annulation and receptor–chromophore electronic matching. Benzofuran- and benzodioxin-annulated naphthalimides bearing either a dimethylaminoethyl receptor or a non-donating alkyl substituent at the imide nitrogen were synthesized using tailored synthetic strategies. Their photophysical properties were investigated by absorption and fluorescence spectroscopy, while sensing performance was evaluated by fluorescence titrations. Quantum chemistry calculations were employed to rationalize experimental observations. Benzofuran-annulated derivatives exhibit structured π–π* absorption bands and strong fluorescence, whereas introduction of the receptor induces efficient fluorescence quenching via reductive PET. Protonation or metal ion coordination suppresses PET and leads to pronounced fluorescence enhancement, particularly in the presence of Cu(II) and Sn(II). In contrast, benzodioxin-annulated derivatives display intramolecular charge-transfer absorption bands, large Stokes shifts, and low fluorescence quantum yields in polar media, resulting in a negligible sensing response. Computational results attribute this behavior to an unfavorable energy arrangement of the donor–acceptor orbitals. Overall, the study demonstrates that heterocyclic annulation critically governs the electronic structure and sensing performance of naphthalimide fluorophores, providing guidelines for the rational design of PET-based optical sensors. Full article

Sustainable aquaculture growth necessitates innovative strategies to meet the global protein demand while minimizing environmental impacts. This narrative review synthesizes the current understanding and emerging approaches for optimizing nutrient cycling and trophic transfer efficiency in pond-based aquaculture systems. We highlight two primary strategies: ‘demand-oriented feeding’, which adaptively balances feed inputs with natural food availability, and the ‘nutritious pond concept’, which enhances pond ecology through carbon/nitrogen ratio management and waste-driven nutrient recycling. A critical examination of the scalability and environmental trade-offs associated with these strategies is also presented. Despite the challenges presented by these strategies, their combination could create a more dynamic, ecosystem-based approach to aquaculture that is more resource-efficient and environmentally friendly, contributing to the development of ponds as sustainable, productive ecosystems that enhance efficiency, reduce waste, and support economic viability. Finally, we explored polyculture as an ecological strategy, highlighting its synergistic mechanisms for maximizing food web efficiency and its potential to enhance the two primary strategies. Full article

The sole use of carbon nanotubes (CNTs) as single-electrode carriers in direct methanol fuel cells (DMFCs) creates structural disparities that increase resistance, impair catalyst utilization, and limit discharge duration. This study presents a novel dual-electrode CNT-based carrier structure designed to enhance mass transport and electron conduction, thereby improving DMFC power output and durability. The CNTs were grown in situ via nitrogen sintering onto the microporous layer, with parameters optimized to enhance surface morphology and conductivity. The impact of this dual-electrode CNT carrier was evaluated through microstructural characterization, cyclic voltammetry, electrochemical performance testing, and service life assessment. Results demonstrate that the structure improves catalyst dispersion, electrochemical active surface area (ECSA), and charge transfer efficiency, while reducing ohmic resistance and charge transfer impedance. Compared to traditional carbon black (CB) carriers, peak power increased by 51.06%. Under China Light Vehicle Test Cycle (CLTC) conditions, discharge duration increased by a factor of 1.7, indicating higher energy efficiency. These improvements are attributed to the dual-electrode architecture’s synergistic enhancement of proton transport, balanced electrochemical kinetics, and reduced interfacial resistance. Full article

Post-viral pulmonary fibrosis represents a clinically significant and mechanistically complex consequence of severe respiratory infection. The COVID-19 pandemic has highlighted that a subset of survivors, particularly those with severe pneumonia or acute respiratory distress syndrome, develop persistent fibrosis-like lung abnormalities, including reticulation and traction bronchiectasis, often accompanied by impaired gas transfer. Although the clinical course is heterogeneous and many lesions regress over time, longitudinal studies indicate that structural and functional impairment may persist for years in susceptible individuals. Oxidative stress has emerged as a plausible convergent mechanism linking acute epithelial injury, dysregulated inflammatory resolution, and chronic fibrotic remodeling. Reactive oxygen and nitrogen species amplify inflammatory signaling, promote epithelial cell death and senescence, influence macrophage polarization, and activate canonical profibrotic pathways, notably the TGF-β axis. Redox imbalance is embedded within reinforcing circuits involving NOX4-dependent ROS amplification, mitochondrial dysfunction, endoplasmic reticulum stress, inflammasome activation, and senescence-associated secretory programs. Persistent immune activation and organelle stress may sustain redox dysregulation beyond viral clearance, thereby bridging acute lung injury to maladaptive remodeling. This review integrates epidemiological, clinical, and mechanistic evidence to position oxidative stress as a central mediator of post-viral lung fibrosis and discusses therapeutic and translational implications. Full article

Efficient charge transfer and effective separation of photo-generated charge carriers are pivotal to the photocatalytic process. In this study, a novel CoAl₂O₄@nitrogen-doped graphitic carbon (CoAl₂O₄@NGC) composite photocatalyst was fabricated via a stepwise hydrothermal method coupled with high-temperature calcination, and its photocatalytic performance for CO₂ reduction was systematically investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and photoelectrochemical measurements were employed to characterize the phase structure, microstructure, surface chemical state and photoelectrochemical properties of the catalyst. Spinel-structured CoAl₂O₄ nanoparticles were uniformly anchored on the NGC substrate, forming a well-integrated composite interface. XPS analysis confirmed the coexistence of Co²⁺/Co³⁺ mixed valence states in CoAl₂O₄ which provides abundant redox sites for CO₂ activation. Photocatalytic tests showed that CoAl₂O₄@NGC exhibits excellent catalytic activity and cycling stability, with CO and CH₄ yields of 27.88 μmol·g⁻¹·h⁻¹ and 23.90 μmol·g⁻¹·h⁻¹, respectively. The narrow bandgap (1.54 eV) enhances visible light absorption, while efficient electron-hole separation and reduced charge transfer resistance improve photocatalytic efficiency. Theoretical calculations further reveal that CoAl₂O₄@NGC lowers the adsorption free energy of CO₂ and the energy barrier for COOH formation, thus facilitating the photocatalytic CO₂ reduction. This work provides insights for the design of efficient and stable photocatalysts for CO₂ reduction and deepens the understanding of the synergistic catalytic mechanism in the spinel/nitrogen-doped carbon composite system. Full article

The oxygen evolution reaction (OER), a key half-reaction in electrochemical water splitting, is limited by sluggish multi-electron transfer kinetics, starting extensive research into efficient, low-cost nanoscale electrocatalysts, particularly those based on nickel, cobalt, and iron, as well as mixed-metal, hybrid, and heteroatom-doped carbon-based metal-free systems, as presented here. Ni- and Co-based electrocatalysts show high efficiency for alkaline OER due to optimized nanostructures, surface modifications, heterostructure design, and multi-metal doping, which enhance activity, stability, and electronic properties. Their performance relies on precise atomic-level control of structure and synergistic interactions, enabling them to approach or rival noble-metal catalysts. Iron-based electrocatalysts are also promising due to their abundance, low cost, and flexible redox chemistry, forming active iron oxyhydroxide species during operation; however, their low conductivity requires structural and electronic optimization. Beyond Fe, Ni, and Co, copper-based compounds, zeolitic imidazolate framework-derived structures, and manganese phosphide–cerium oxide composites offer enhanced oxygen vacancies, tunable structures, and strong interfacial synergy. Furthermore, heteroatom-doped carbon materials incorporating nitrogen, phosphorus, or sulfur improve catalytic activity by modifying electronic structure, creating active sites, and enhancing charge transfer. Overall, careful control of composition, structure, and electronic properties enables the development of efficient, durable, and scalable noble-metal-free catalysts for OER. Full article