Search Results (189)

Detecting trace metals in soil across geologically diverse terrains remains challenging due to complex mineral–metal interactions and the limited spatial coverage of traditional geochemical tests. This study develops a scalable VIS–NIR–SWIR spectroscopy and machine learning (ML) framework to predict and map soil concentrations of Cr, As, Cu, and Cd in the Aligudarz District, located within the geotectonically complex Sanandaj–Sirjan Zone of western Iran. Laboratory reflectance spectra (~350–2500 nm) obtained from 110 soil samples were pre-processed using derivative filtering, scatter-correction techniques, and genetic algorithm (GA)-based wavelength optimisation to enhance diagnostic absorption features linked to Fe-oxides, clay minerals, and carbonates. Multiple ML-based approaches, including artificial neural networks (ANNs), support vector regression (SVR), and partial least squares regression (PLSR), as well as stepwise multiple linear regression (SMLR), were compared using nested, spatial, and external validation. Nonlinear models, particularly ANNs, exhibited the highest predictive accuracy, with strong generalisation confirmed via an independent test set. GA-selected wavelengths and derivative-enhanced spectra revealed mineralogical controls on metal retention, confirming that spectral predictions reflect underlying geological processes. Ordinary kriging of spectral-ML residuals generated spatially consistent metal-distribution maps that aligned well with local and regional geological features. The integrated framework demonstrates high predictive accuracy and operational scalability, providing a reproducible, field-ready method for rapid geochemical assessment. The findings highlight the potential of VIS–NIR–SWIR spectroscopy, combined with advanced modelling and geostatistics, to support environmental monitoring, mineral exploration, and risk assessment in geologically complex terrains. Full article

Heavy metals (HMs) and metal-oxide nanoparticles (NPs) frequently co-occur in freshwater systems, yet their combined effects on microbial predators remain poorly understood. Here, the freshwater ciliate Coleps hirtus was used to evaluate the cytotoxicity of single and binary mixtures of HMs (Cd, Cu, Zn) and NPs (ZnO, CuO, TiO₂, SiO₂), and to characterize associated antioxidant responses. Acute toxicity was assessed after 24 h by estimating LC₂₀ and LC₅₀ values, while mixture toxicity for Cd + Zn and Cd + ZnO was analyzed using the Toxic Unit approach and the MixTOX framework. Non-enzymatic (TPC, DPPH, HRSA) and enzymatic (CAT, GST, GPx, SOD) antioxidants were quantified as sublethal biomarkers at concentrations below lethal thresholds. HMs were markedly more toxic than NPs, with a toxicity ranking of Cu > Cd >> Zn, whereas NPs followed ZnO > CuO >> TiO₂ >> SiO₂. Cd + Zn mixtures showed predominantly antagonistic or non-interactive effects, while Cd + ZnO mixtures exhibited strong synergistic toxicity with a non-linear dependence on mixture composition, as supported by MixTox modeling. Exposure to HMs and NPs induced significant and often coordinated changes in antioxidant biomarkers, with binary mixtures eliciting stronger responses than single contaminants. Together, these findings indicate that mixture composition strongly influences both toxicity outcomes and oxidative stress responses in C. hirtus. The combination of clear, mixture-dependent toxicity patterns and robust oxidative stress responses makes C. hirtus a promising bioindicator for freshwater environments impacted by HMs and NPs. Full article

Two structurally tunable (propyl-3-ol)triphenyltin(IV) (Ph₃SnL₁) and (butyl-4-ol)triphenyltin(IV) (Ph₃SnL₂) compounds were investigated at the human serum transferrin (Tf) molecular interface to resolve how ligand architecture and protein metallation modulate organotin(IV) biocompound stability and lobe-selective binding. Steady-state fluorescence spectroscopy revealed efficient quenching of native Tf emission (λ_ex = 280 nm, 296–310 K, pH 7.4) without significant spectral displacement, indicating the predominant formation of non-fluorescent ground-state complexes. Calculated bimolecular quenching constants (K_q ~10¹² M⁻¹ s⁻¹) exceeded the diffusion-controlled aqueous limit, ruling out a collisional dynamic quenching mechanism and confirming static complexation as the principal origin of fluorescence suppression. Double-log binding analysis revealed moderate affinity (K_a ~10²–10³ M⁻¹) and an approximately single dominant binding event per protein (n ≈ 0.65–0.90). Temperature-dependent van’t Hoff evaluation yielded positive ΔH° and ΔS° values, supporting a spontaneous, entropy-favored association process largely governed by hydrophobic and dispersion-type contributions, consistent with lipophilic organotin(IV) scaffold accommodation. Iron (Fe³⁺) loading of Tf markedly enhanced ligand engagement, especially for Ph₃SnL₁, evidencing that metallation-induced lobe closure reshapes pocket accessibility and local polarity relevant for organotin(IV) binding presentation rather than simply strengthening empirical docking scores. Molecular docking localized the most stable Ph₃SnL₂ poses in the sterically confined, rigid C-lobe, while Ph₃SnL₁ preferentially penetrated the more adaptive N-lobe. ONIOM QM/MM refinement of docking poses confirmed strong interfacial stabilization (ΔE_int ≈ –38 to –62 kcal mol⁻¹) and clarified charge–packing interplay without invoking frontier orbital analysis. The results map multiscale structure–interaction relationships defining lobe preference and complex stability at the transferrin interface. Full article

Air pollution is a major but often under-integrated driver of forest dynamics at the global scale. This review combines a bibliometric analysis of 258 peer-reviewed studies with a synthesis of ecological, physiological, and biogeochemical evidence to clarify how multiple air pollutants influence forest structure, function, and regeneration. Research output is dominated by Europe, East Asia, and North America, with ozone, nitrogen deposition, particulate matter, and acidic precipitation receiving the greatest attention. Across forest biomes, air pollution affects growth, wood anatomy, nutrient cycling, photosynthesis, species composition, litter decomposition, and soil chemistry through interacting pathways. Regional patterns reveal strong context dependency, with heightened sensitivity in mountain and boreal forests, pronounced ozone exposure in Mediterranean and peri-urban systems, episodic oxidative stress in tropical forests, and long-term heavy-metal accumulation in industrial regions. Beyond being impacted, forests actively modify atmospheric chemistry through pollutant filtration, aerosol interactions, and deposition processes. The novelty of this review lies in explicitly framing air pollution as a dynamic driver of forest change, with direct implications for afforestation and restoration on degraded lands. Key knowledge gaps remain regarding combined pollution–climate effects, understudied forest biomes, and the scaling of physiological responses to ecosystem and regional levels, which must be addressed to support effective forest management under global change. Full article

Metal–organic framework (MOF) materials were extensively studied in the removal of pollutants in wastewater. However, catalysts in the powder form usually suffered from the strong tendency to agglomerate and the intricate operation for recycling, which significantly limited their practical application. In comparison, monolithic catalysts with their high macroscopic operability and recoverability as well as impressive specific surface area have attracted tremendous attention in recent years. To address these issues, a monolithic Fe-based catalyst was prepared via in situ synthesis, using nickel–iron foam (NFF) as the substrate with cobalt (Co) incorporation. XPS analysis showed that Co doping enhanced the synergistic interaction among Fe, Ni, and Co, accelerating the redox cycle among species, thus improving electron transfer and laying a kinetic foundation for efficient peroxymonosulfate (PMS) activation. Quenching experiments and EPR indicated singlet oxygen (¹O₂) as the main reactive species; Co doping shifted the degradation pathway from radicals to non-radicals. Under optimized conditions (PMS: 0.08 mmol/L; catalyst: 1 cm²; initial Chlortetracycline (CTC): 50 mg/L), 95.7% CTC degradation was achieved within 60 min, and efficiency only dropped to 90.5% after 5 cycles. This catalyst provided theoretical and technical support for the application of monolithic MOF-derived catalysts and highly efficient PMS activators. Full article

Plant–microbe interactions exert a significant influence on host stress responses; however, the molecular mechanisms underlying these effects remain inadequately understood. In this study, we characterize FaMAN8, an α-mannosidase from Fragaria × ananassa, to explore its role in adaptation to heat waves and water deficit, as well as its modulation by fungal endophytes. Transcriptomic analysis identified FaMAN8 as the sole α-mannosidase isoform highly conserved across reported sequences, with root-specific induction under conditions of heat stress, deficient irrigation, and endophytic colonization. Structural modeling revealed that FaMAN8 exhibits the canonical domain organization of glycoside hydrolase family 38 (GH38) enzymes, featuring a conserved catalytic architecture and metal-binding site. Molecular docking and dynamics simulations with the Man₃GlcNAc₂ ligand indicated a stable binding pocket involving key catalytic residues and strong electrostatic complementarity. MM-GBSA and free energy landscape analyses further supported the thermodynamic stability of the protein–ligand complex. Cavity analysis revealed a larger active site in FaMAN8 compared to its homolog JbMAN, suggesting broader substrate accommodation. Collectively, these findings identify FaMAN8 as a stress-responsive glycosidase potentially involved in glycan remodeling during beneficial root–fungus interactions. This work provides molecular insights into plant–microbe symbiosis and lays the groundwork for microbiome-informed strategies to enhance crop stress resilience. Full article

Single-atom catalysts are highly efficient electrocatalysts for water splitting with exceptional atomic utilization, but atomic aggregation can impair their catalytic performance. To address this challenge, a Fe-Co-Ni single-atom bifunctional catalyst supported on nitrogen-doped graphene oxide was designed and employed for overall water splitting in alkaline electrolyte. The catalyst’s composition, structure, and morphology were systematically characterized using XRD, XPS, SEM, and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Electrochemical evaluations were performed to assess its activity and stability toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The results demonstrate that strong metal-nonmetal interactions between the Fe, Co and Ni single atoms and the nitrogen-doped graphene oxide support facilitate stable and uniform anchoring of the metal centers on the wrinkled carbon framework. The total metal loading reaches approximately 6.78 wt%, ensuring a high density of accessible active sites. Furthermore, synergistic electronic coupling among the Fe, Co, and Ni centers enhances charge transfer kinetics and modulates the D-band electronic states of the metal atoms. This effect weakens the adsorption strength of hydrogen and oxygen-containing intermediates, thus promoting faster reaction kinetics for both HER and OER. Consequently, the FeCoNi/CNG catalyst delivers low overpotentials of 77 mV for HER and 355 mV for OER at a current density of 10 mA cm⁻² in alkaline conditions. When integrated into an alkaline water electrolyzer, the system achieves a cell voltage of only 1.68 V to attain a current density of 10 mA cm⁻², underscoring its outstanding bifunctional catalytic performance. Full article

Dry reforming of methane (DRM) is a promising method for turning two major greenhouse gases, CO₂ and CH₄, into syngas (H₂ + CO). This syngas has the right H₂/CO ratio for making valuable chemicals and liquid fuels. However, there are significant challenges that make it tough to implement commercially. One big issue is that the process requires a lot of energy because it is highly endothermic, needing temperatures over 700 °C. This high heat can quickly deactivate the catalyst due to carbon build-up (coking) and the thermal sintering of metal nanoparticles. Researchers increasingly recognize mechanochemistry—a non-thermal, solid-state technique employing mechanical force to drive chemical transformations—as a sustainable, solvent-free strategy to address these DRM challenges. This mini-review critically assesses the dual role of mechanochemistry in advancing DRM. First, we examine its established role in creating advanced catalysts at lower temperatures. Here, mechanochemical methods help produce well-dispersed nanoparticles, enhance strong interactions between metal and support, and develop bimetallic alloys that resist coke formation and show great stability. Second, we delve into the exciting possibility of using mechanochemistry to directly engage in the DRM reaction at near-ambient temperatures, which marks a major shift from traditional thermocatalysis. Lastly, we discuss the key challenges ahead, like scalability and understanding the mechanisms involved, while also outlining future directions for research to fully harness mechanochemistry for converting greenhouse gases sustainably. Full article

Fullerene-supported single-atom catalysts (SACs) have emerged as a promising class of materials for electrocatalytic overall water splitting, offering a route to reduce reliance on scarce and costly precious metals. This review systematically summarizes recent advances in the design, synthesis, and application of fullerene-based SACs, with an emphasis on their unique structural, electronic, and catalytic properties. The exceptional stability, conductivity, and surface chemistry of fullerenes enable strong interactions with metal atoms, allowing high dispersion and enhanced catalytic performance for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Recent studies demonstrate that C₆₀- and C₂₄-based materials, when combined with transition metals such as Pt, Ru, and V, exhibit superior HER/OER activity, bifunctionality, and spin-selective catalytic pathways. The vast structural space of fullerene–metal combinations presents new opportunities, which can be efficiently explored using machine learning and high-throughput simulations. By integrating density functional theory, transition state modeling, and data-driven techniques, this emerging research frontier is paving the way for rational catalyst design. The review concludes by proposing a machine learning-assisted framework to predict and screen high-performance fullerene-based SACs, ultimately accelerating the development of efficient, stable, and scalable electrocatalysts for sustainable hydrogen production. Full article

Plastics are essential to technological and industrial development, yet their prevalent single-use life and poor recycling rates are contributing to escalating environmental concerns. Expanded polystyrene (EPS), although valued for being lightweight, durable, and insulating, poses a significant challenge as it is typically disposed of after a single use. Furthermore, traditional recycling is limited because it requires clean, well-separated waste. Therefore, it remains necessary to develop recycling strategies that maximize the value of plastics. To address this issue, the present work aims to provide a comparative evaluation of the synthesis and characterization of FeMg/Al₂O₃ and Fe/Al₂O₃-MgO as catalysts, along with an analysis of their catalytic performance in the pyrolysis of EPS waste at varying temperatures and catalyst loadings. The results showed an advantage in using catalysts in the pyrolysis of EPS waste; however, the FeMg/Al₂O₃ (15 wt.%) catalyst demonstrated the best efficiency in the pyrolysis of EPS waste at 400 °C, achieving 96% liquid yield and reducing reaction times by up to 45% due to its high metal dispersion and strong metal-support interaction, which promotes faster and more efficient conversion. In contrast, Fe/Al₂O₃-MgO showed lower catalytic performance, although it can offer lower synthesis costs and good thermal stability, making it more viable on a large scale. These findings represent a significant advance in catalytic EPS recycling, offering promising strategies to promote the circular economy of EPS and extend its useful life. Full article

This study evaluated regional and seasonal variations in cobalt (Co), cadmium (Cd), and lead (Pb) concentrations in the serum and milk of she-camels and their calves across five regions of Saudi Arabia to evaluate their potential as bioindicators of environmental contamination. A total of 450 biological and environmental samples (serum, milk, soil, water, and feed) were analyzed using inductively coupled plasma optical emission spectrometry (ICP–OES). Regional, seasonal, and physiological effects were assessed by analysis of variance and Pearson correlation. Serum Co varied significantly (p < 0.05) by region and season, with the highest values in the Eastern region during spring. She-camel cadmium showed significant regional differences, particularly higher concentrations in the Southern region, while Pb displayed pronounced seasonal variation, peaking in spring serum and milk of she-camel. In she-camel milk, Co, Cd, and Pb were significantly influenced by region and season interactions (p < 0.05). Correlation analysis revealed strong positive associations between Cd and Pb (r = 0.85, p < 0.001) and between Co and Pb (r = 0.70, p < 0.01), indicating shared exposure pathways. In conclusions, although all metal concentrations remained below FAO/WHO permissible limits, the observed variability highlights the camel’s value as a bioindicator of environmental contamination. Continued monitoring is recommended to safeguard food safety and support Saudi Vision 2030 sustainability goals. Full article

This research focuses on environmental challenges and has considerable importance, as Ni, Cu, Zn, Cr, As, Hg, and Pb heavy metals pose potential hazards for plants as well as for microorganisms that are useful for plants. The binding affinity of a protochelin siderophore with transition metals was computationally analyzed utilizing density functional theory (DFT). The hybrid DFT functional PBE0, def2-SVP, and def2-TZSVP basis sets were utilized to optimize the complex geometry and determine the interaction energy of various protochelin–metal complexes. Among the metal contaminants studied (Cr⁺⁶, Cr⁺³, Ni⁺², Cu⁺², Zn⁺², As⁺³, Hg⁺², and Pb⁺²), Cr⁺⁶ has a strong affinity for protochelin, and the order of stability of the protochelin–metal complexes is as follows: protochelin–Cr⁺⁶ > protochelin–As⁺³ > protochelin–Cr⁺³ > protochelin–Fe⁺³ > protochelin–Ni⁺² > protochelin–Cu⁺² > protochelin–Pb⁺² > protochelin–Zn⁺² > protochelin–Hg⁺². The results are also supported by NCI, FMOs, DOS spectra, and RMSD analysis. Computational research suggests that bioremediation may be a great method for eliminating metal contaminants from groundwater and soil due to its eco-friendly nature and environmental preservation. Full article

Dry reforming of methane and ethanol is a promising catalytic process for the conversion of carbon dioxide and hydrocarbon feedstocks into synthesis gas (H₂/CO), which serves as a key platform for the production of fuels and chemicals. Over the past decade, substantial progress has been achieved in the design of catalysts with enhanced activity and stability under the demanding conditions of these strongly endothermic reactions. This review summarizes the latest developments in catalyst systems for DRM and EDR, including Ni-based catalysts, perovskite-type oxides, MOF-derived materials, and high-entropy alloys. Particular attention is given to strategies for suppressing carbon deposition and preventing metal sintering, such as oxygen vacancy engineering in oxide supports, rare earth and transition metal doping, strong metal–support interactions, and morphological control via core–shell and mesoporous architectures. These approaches have been shown to improve coke resistance, maintain metal dispersion, and extend catalyst lifetimes. The review also highlights emerging concepts such as multifunctional hybrid systems and innovative synthesis methods. By consolidating recent findings, this work provides a comprehensive overview of current progress and future perspectives in catalyst development for DRM and EDR, offering valuable guidelines for the rational design of advanced catalytic materials. Full article

Understanding how redox-active ligands coordinate to metal centers of different oxidation states is essential for applications ranging from metal remediation and recycling to drug discovery. In this study, coordination complexes of nickel(II), copper(II), and zinc(II) chloride salts were synthesized by mixing the salts with either arylazoformamide (AAF) or arylazothioformamide (ATF) ligands in toluene or methanol. The AAF and ATF ligands coordinate through their 1,3-heterodienes, N=N–C=O and N=N–C=S, respectively, and, due to their known strong binding, the piperidine and pyrrolidine formamide units were selected, as was the electron-donating methoxy group on the aryl ring. A total of 12 complexes were obtained, representing potential chelation events from ligand-driven oxidation of zerovalent metals and/or coordination of oxidized metal salts. The X-ray crystallography revealed a range of coordination patterns. Notably, the Cu(II)Cl₂ complexes, in the presence of ATF, produce [ATF-CuCl]₂ dimers, supporting a potential reduction event at the copper, while other metals with ATF and all metals with AAF remain in the 2+ oxidation state. Hirshfeld analysis was performed on all complexes, and it was found that most interactions across the complexes were dominated by H…H, followed by Cl…H/H…Cl, with metals showing very little to no interaction with other atoms. Spectroscopic techniques such as UV–VIS absorption, NMR (when diamagnetic), and FTIR, in addition to electrochemical studies support the metal–ligand coordination. Full article

This study reports, for the first time, lanthanum oxide (La₂O₃) nanoparticles (NPs) that simultaneously suppress osteosarcoma MG63 cell proliferation and promote normal Vero cell viability, a dual effect not previously documented for La₂O₃ or similar metal oxide NPs. Physico-chemical characterization revealed a unique needle-like morphology, cubic crystallinity, and dispersion stability in DMSO without acidic dispersants, properties that can influence cellular uptake, ROS modulation, and biocompatibility. Comprehensive characterization (fluorescence spectroscopy, particle size/zeta potential, Raman, XRD, TGA, ATR-FTIR, and TEM) confirmed structural stability and surface chemistry relevant to biological interactions.La₂O₃ NPs exhibited broad-spectrum antibacterial activity (Gram-positive Streptococcus pyogenes, Bacillus cereus; Gram-negative Escherichia coli, Pseudomonas aeruginosa) and strong enzymatic/non-enzymatic antioxidant capacity, supporting potential use in implant coatings and infection control. MTT assays demonstrated dose-dependent cytotoxicity in MG63 cells, with enhanced proliferation in Vero cells. In zebrafish embryos, developmental toxicity assays yielded an LC₅₀ of 2.6 mg/mL higher (less toxic) than values reported for Ag NPs (~0.3–1 mg/mL) with normal development at lower concentrations and dose-dependent malformations (e.g., impaired somite formation and skeletal deformities) at higher doses. Collectively, these findings position La₂O₃ NPs as a multifunctional platform for oncology and regenerative medicine, uniquely combining selective anticancer activity, normal cell support, antimicrobial and antioxidant functions, and a defined developmental safety margin. Full article