Search Results (422)

At low temperatures, the preferential removal of CO from the fuel feed of PEMFC is a critical factor for ensuring the optimal performance of fuel cells. In this study, Au/TiO₂-PD and Au/TiO₂-DP catalysts were synthesized via in situ photo-deposition and deposition–precipitation methods, respectively. The catalytic performance for CO preferential oxidation was evaluated in a hydrogen-rich atmosphere, and the effects of visible light irradiation on catalytic activity and selectivity were systematically investigated. The Au/TiO₂-DP catalyst exhibited a relatively low CO conversion under dark conditions in the hydrogen-rich atmosphere, while visible light irradiation significantly enhanced its CO oxidation activity and selectivity. In contrast, the Au/TiO₂-PD catalyst achieved a high CO oxidation conversion, but suffered from low CO oxidation selectivity; moreover, visible light exerted a weak inhibitory effect on its selectivity. Combined characterization results from temperature-programmed desorption (TPD), temperature-programmed surface reaction (TPSR), in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and in situ electron paramagnetic resonance (EPR) revealed that the Au/TiO₂-PD catalyst possessed stronger hydrogen adsorption, dissociation and oxidation capabilities than the Au/TiO₂-DP catalyst. The rapid dissociation of hydrogen molecules over the Au/TiO₂-PD catalyst accelerated the activation of adsorbed oxygen species and simultaneously promoted the formation of water via hydrogen oxidation. Excessive water accumulation on the catalyst surface occupied the active sites for CO oxidation, thereby imposing an overall inhibitory effect on CO preferential oxidation. Full article

Electron behaviors—including how electrons interact with energy, matter, and magnetic fields—form the foundation of many biomedical imaging modalities, including X-ray imaging, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), optical imaging, electron microscopy, atomic force microscopy, and electron paramagnetic resonance (EPR). These interactions allow visualization of internal structures, molecular processes, tissue composition, oxygenation, redox biology, and high-resolution cellular or surface features. This narrative review provides an overview of key electron-associated mechanisms and their applications in biomedical imaging. Advanced MRI methods, including magnetic resonance spectroscopy, chemical exchange saturation transfer, relayed nuclear Overhauser effect imaging, dynamic nuclear polarization, and hyperpolarized 13C MRI, are highlighted as examples of molecular and metabolic imaging. By comparing modalities across contrast mechanism, spatial and temporal scale, penetration depth, sensitivity, clinical utility, and technological maturity, this review provides a framework for understanding established imaging approaches and contextualizing emerging biomedical imaging technologies. Full article

This study investigated the valorisation potential of dried and frozen pomace obtained as by-products from the processing of Rosa rugosa fruits. The antioxidant activity of the pomace was assessed using electron paramagnetic resonance (EPR) spectroscopy with the TEMPO radical. Total phenolic content was determined using the Folin–Ciocalteu method, and individual phenolic compounds were analysed by UHPLC. Frozen pomace exhibited significantly higher antioxidant activity than dried pomace (2.76 vs. 1.64 mmol TE/100 g d.m.) and contained greater amounts of ellagic acid (19.29 vs. 13.08 mg/100 g d.m.), gallic acid (17.05 vs. 5.07 mg/100 g d.m.), procyanidin B2 (14.92 vs. 11.88 mg/100 g d.m.), and catechin (2.84 vs. 1.12 mg/100 g d.m.). To assess technological applicability, Rosa rugosa pomace was incorporated into an agar-based model fruit gel system at levels of 3%, 5%, and 10% (w/w). The enriched gels were evaluated in terms of antioxidant activity, total phenolic content, and physicochemical parameters, including colour, water activity, and moisture content. The incorporation of pomace into gel systems was found to significantly increase the total phenolic content, raising it from 48.64 mg GAE/100 g in the control sample to 267.56 mg GAE/100 g in gels containing 10% pomace. Antioxidant activity also increased, rising from 335.79 to 1264.37 μmol TE/100 g. The addition of pomace was also found to reduce the moisture content from 71.02% to 64.17%, while the water activity remained stable (0.821–0.840). Sensory evaluation indicated that gels containing 3–5% pomace achieved the highest consumer acceptance. These results demonstrate that Rosa rugosa pomace is a valuable and sustainable source of functional ingredients that can enhance the bioactive properties of food products while maintaining desirable physicochemical characteristics. Full article

The increasing prevalence of multiclass pesticide residues in aquatic environments poses a significant threat to ecosystems and human health. To address this challenge, magnetic Fe₃O₄@Co₅Al-LDH nanoparticles were synthesized as high-performance, easily recoverable catalysts for the peroxymonosulfate (PMS)-mediated degradation of epoxiconazole, atrazine, and metalaxyl. Under optimized conditions (pH 7.0, 35 mg catalyst, and 4.0 mM PMS), the system achieved 100% degradation of the three coexisting pesticides within 15 min. Quenching experiments and electron paramagnetic resonance (EPR) spectroscopy confirmed that SO₄⁻ and ^•OH radicals were the primary reactive species driving the process. Liquid chromatography–mass spectrometry (LC-MS) analysis identified four intermediates for epoxiconazole, three for atrazine, and four for metalaxyl, facilitating the proposal of distinct degradation pathways. The degradation mechanism revealed that electron transfer between Fe/Co and PMS promoted the generation of reactive oxygen species, leading to dechlorination, hydroxylation, and dealkylation of the pesticides transiently adsorbed on the surface of Fe₃O₄@Co₅Al-LDH. In summary, this study demonstrates that Fe₃O₄@Co₅Al-LDH is an easily recoverable, reusable, and cost-effective catalyst for the simultaneous remediation of complex pesticide mixtures in water. Full article

The western honey bee (Apis mellifera) is increasingly exposed to environmental stressors that affect redox homeostasis, leading to imbalances in cellular functions. Natural bioactive compound-based nutritional strategies show promise in reducing oxidative stress while preserving redox signaling. In this study, we investigated the chemical composition, cytotoxicity, and redox-modulating effects of an aqueous extract of the edible mushroom Agaricus bisporus on the AmE-711 honey bee cell line. High-resolution Orbitrap LC–MS analysis revealed a chemically diverse extract comprising polyols, organic acids, amino acids, phosphorylated sugars, nucleotide derivatives, phenolic, and lipid-related compounds. Among the identified metabolites were mannitol, malic acid, citric acid, glutamic acid, and uridine diphosphate N-acetylglucosamine, providing a biochemical basis for potential metabolic and redox-related activity. Cell viability assays demonstrated that A. bisporus extract exhibited no significant cytotoxicity under the experimental conditions. Electron paramagnetic resonance (EPR) spectroscopy with the TEMPONE spin probe showed that untreated cells exhibited only minimal signal reduction (4.20%), while treatment with the extract alone caused a moderate decrease (12.08%), indicating the absence of reductive stress. Oxidative stress induced by hydrogen peroxide resulted in a pronounced TEMPONE signal reduction (37.88%), whereas co-treatment with the A. bisporus extract substantially attenuated this effect, lowering the signal reduction to 15.34%. These findings suggest that the aqueous A. bisporus extract may help preserve basal redox activity while attenuating peroxide-induced oxidative stress in AmE-711 honey bee cells. Rather than acting as a potent radical scavenger, the extract appears to function as a mild redox modulator or stabilizer under the tested conditions, which may be beneficial for honey bee cellular redox balance. These results support further investigation of physiologically appropriate A. bisporus-based dietary supplements for mitigating oxidative stress in apicultural systems. Full article

MgCr₂O₄ nanospinel samples were synthesized using a modified Pechini method, followed by controlled calcination. The resulting materials were evaluated in terms of crystal structure, particle morphology, and optical and electronic properties. Their oxidative activity towards the degradation of organic dyes was investigated via photocatalysis, Fenton-like, and photon-Fenton-like processes. Various analytical techniques were employed to characterize the samples, including X-ray diffraction (XRD) with Rietveld refinements, infrared (IR) spectroscopy, UV–Vis spectroscopy, colorimetry, and transmission and high-resolution transmission electron microscopy (TEM/HRTEM). Structural characterization revealed that MgCr₂O₄ crystallized after calcination at 600 °C, and Rietveld refinements confirmed cubic Fd-3m symmetry. IR spectra confirmed the short-range order through the presence of vibrational modes assigned to CrO₆^2- octahedra. UV–Vis spectroscopy indicated mixed Cr valences (Cr³+/Cr⁶+) for samples calcined at temperatures below 900 °C, with Cr⁶+ eliminated at higher temperatures, confirmed by electron paramagnetic resonance (EPR) spectroscopy. This suggests that an oxidation reaction occurred due to oxygen vacancies in the lattice. Optical bandgap (Eg) increased with temperature. Samples calcined at low temperatures were dark green and became more saturated at temperatures above 900 °C, suggesting photoresponse to visible light, as indicated by the Eg values. The oxidative activity of the nanospinels in degrading the dyes methylene blue (MB) and rhodamine B (RhB) under visible light depended on the nature of the dye, the catalyst concentration, and the use of H₂O₂ in the process to improve the formation of hydroxyl radicals (•OH), as confirmed by photohydroxylation of terephthalic acid (TA). The highest degradation rate was observed in the photo-Fenton-like process, with 96% and 97% degradation of RhB and MB dyes in 60 min, reaching a kinetic rate constant (${\mathit{K}}_{app}$) of 0.055 min⁻¹ and 0.051 min⁻¹, respectively. This study highlights the importance of controlling various parameters to promote the formation of reactive oxygen species (ROS) required for oxidative degradation by nanospinels. Full article

This study investigates the degradation of propranolol, a widely detected beta-blocker in natural water, using an ultraviolet/peracetic acid (UV/PAA) system. The UV/PAA system significantly enhanced the degradation efficiency compared to UV or PAA alone, achieving a 90.67% removal of propranolol after 15 min under optimal conditions. The degradation process was found to follow first-order kinetics, with a rate constant 36 times higher than that of UV. Reactive species such as hydroxyl radicals (^·OH) and organic radicals (RO^·) were identified through quenching experiments and electron paramagnetic resonance (EPR) spectroscopy. The degradation mechanism was further explored using density functional theory (DFT), revealing the molecular sites most susceptible to radical attacks. This study provides new insights into the application of UV/PAA systems for the removal of beta-blockers and contributes to the optimization of advanced oxidation processes in water treatment. Full article

The development of sustainable technologies capable of simultaneously addressing environmental pollution and renewable energy production remains a major scientific challenge. In this work, titanium dioxide nanoparticles (GTiO₂) were synthesized through a plant-extract-assisted route using Punica granatum (pomegranate) peel extract and subsequently modified with platinum nanoparticles (Pt NPs) to obtain an efficient photocatalyst for the photoreforming of organic pollutants. The resulting Pt-GTiO₂ material exhibited an anatase crystal structure with an average crystallite size of approximately 12 nm and a specific surface area of about 140 m² g⁻¹. Comprehensive characterization using XRD, BET, TEM, FTIR, Raman, and photoluminescence spectroscopy (PL) revealed favorable structural and optoelectronic properties that promote efficient charge separation. The photocatalytic performance of Pt-GTiO₂ was evaluated through the simultaneous degradation of 2-naphthol, a priority aromatic pollutant, and hydrogen evolution under simulated solar irradiation in anaerobic conditions. Under the investigated conditions, Pt-GTiO₂ effectively promoted 2-naphthol degradation, with substantial but incomplete mineralization, as confirmed by TOC removal. The synthesized catalyst showed degradation efficiency higher than Pt-UV100 and comparable to Pt-P25, while exhibiting superior hydrogen evolution when compared with Pt-P25. Mechanistic investigations combining scavenger experiments, electron paramagnetic resonance (EPR) spectroscopy, and the identification of reaction intermediates suggest that photogenerated holes play a major role in the initial oxidation step under the mechanistic test conditions. The detected intermediates indicate that photoreforming proceeds via multiple pathways, including hydroxylation, ring-opening, reduction, and fragmentation. These findings highlight the potential of biogenic TiO₂-based photocatalysts for converting hazardous organic pollutants into clean hydrogen fuel while simultaneously achieving wastewater purification, offering a promising route toward sustainable environmental and energy technologies. Full article

To improve the removal efficiency of sulfamethoxazole (SMX) in soil and to elucidate the role of soil organic matter (SOM) in peroxydisulfate (PDS)-based in situ chemical oxidation, a biochar-supported sulfidated nanoscale zero-valent iron (BC@S-nZVI)-activated PDS system was constructed in this study. The removal behavior and removal mechanisms of SMX were systematically compared between aqueous and soil systems, and the regulatory role of SOM was further clarified. Characterization results showed that BC@S-nZVI was successfully constructed with a composite interface consisting of a biochar support framework, an Fe⁰ core, and surface Fe-S structures. Under the optimized conditions, the BC@S-nZVI/PDS system achieved 92.9% removal of SMX within 120 min in the aqueous system, which was significantly higher than that of the nZVI/PDS and BC/PDS systems. In the soil system, the removal efficiency of SMX reached 74.4% within 120 min, and further increased to 91.3% after targeted removal of SOM. Results from radical quenching experiments, electron paramagnetic resonance (EPR) spectroscopy, and chemical probe tests demonstrated that ^•OH and SO₄^•− were the dominant reactive species driving SMX degradation in the aqueous system, while ¹O₂ played an auxiliary role. In contrast, in the soil system, SOM, acting as a natural reductive component, competitively consumed ^•OH and SO₄^•−, thereby markedly suppressing the radical oxidation pathway. Compared with these radical species, ¹O₂ exhibited stronger resistance to background interference and became the key reactive species responsible for the sustained transformation of SMX in soil. These findings demonstrate that the BC@S-nZVI/PDS system has considerable potential for the remediation of antibiotic-contaminated soils and reveal a mechanistic shift from radical-dominated to non-radical-dominated pathways under the interference of soil organic components. Full article

Silicon carbide is a promising material for optically and spin-active point defects relevant to quantum applications. Quantum-relevant color centers are commonly generated by irradiation or implantation, which require specialized infrastructure and may introduce collateral lattice damage. Here, we present a chemical approach in which the influence of synthesis temperature, high-energy ball milling, and aluminum addition on formation, polytype distribution, and defect formation in SiC is investigated. We found that it is possible to create quantum-relevant defects throughout the chemical synthesis, and the temperature and mechanical activation are the dominant parameters governing defect generation. Photoluminescence and electron paramagnetic resonance spectroscopy demonstrate that low synthesis temperatures (1050–1150 °C) in high-energy ball-milled samples yield silicon vacancy and divacancy-related color centers, evidenced by characteristic near-infrared PL emission and high-spin EPR signals with zero-field splitting values D ≈ 1.3 GHz and D ≈ 270 MHz, consistent with neutral divacancies and V_Si–C_Si complex centers, respectively. An additional EPR signal at D ≈ 650–780 MHz, not matched by any previously reported defect configuration in SiC, is tentatively assigned to a second-nearest-neighbor divacancy-like (V_Si–V_C) pair. Full article

Background/Objectives: Chlorogenic acid (CGA) is a natural antioxidant widely distributed in various plant foods, exhibiting great potential for the development of natural antioxidant agents and biomedical applications. Methods: In this study, the antioxidant activity of CGA was first characterized via electron paramagnetic resonance (EPR) spectroscopy by determining its scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. Meanwhile, its hydroxyl radical (•OH) scavenging activity in aqueous solution was quantitatively evaluated based on the signal intensity changes of DMPO-OH• adducts. Furthermore, a fluorescein-labeled chlorogenic acid derivative (FL-CGA) was utilized to visualize the distribution of CGA in major mouse organs following tail vein injection, with a specific focus on the kidney, and to investigate its penetration capacity into podocytes. Results: The results demonstrated that 0.35 mM CGA exerted potent scavenging activity toward highly reactive and cytotoxic •OH radicals, achieving a scavenging rate of 95.2% in a system where •OH was generated by continuous UV irradiation of 5 mM H₂O₂ aqueous solution for 30 min. Additionally, FL-CGA was specifically accumulated in the kidney and localized to the lysosomes of podocytes, while no signal was detected in the endoplasmic reticulum or mitochondria. Conclusions: This study provides experimental evidence to further elucidate the mechanisms underlying CGA-mediated intervention in renal injury, and lays a foundation for the further development and clinical application of CGA as a natural dietary antioxidant. Full article

UV-C irradiation enables digital zirconia colouring. This study investigates the atomic mechanism driving this defect-induced optical change. The band gap was calculated from the absorption spectra with the Tauc plot. The absorption spectra were measured using UV–visible spectroscopy. The surface composition was evaluated through X-ray photoelectron spectroscopy (XPS). The location of the oxygen vacancy was tested through electron paramagnetic resonance (EPR). The computer calculation using Density Functional Theory was conducted and the density of states (DOSs) were calculated. The band gap reduced rapidly from the baseline group (3.184 eV) to the 30 min irradiated group (3.097 eV). The XPS results showed that the electron density around O1s reduced and the electron density around Zr 3d increased. The EPR signal (g = 2.0037) increases progressively as the UV-C irradiation time is prolonged from 15 min to 24 h, indicating the accumulation of paramagnetic defect centres. The DOSs suggested the emergence of defect-associated states and band-edge tailing in oxygen deficient models, consistent with the experimentally observed reduction in the Tauc-derived optical band gap. This study confirmed the mechanism by which UV-C-induced oxygen vacancies modify the colour of 3Y-TZP. Full article

Photo-Fenton technology is considered an effective method for removing organic pollutants from water. In this work, a novel Mn-doped FeWO₄ (Mn-FeWO₄) photocatalyst was synthesized via a one-step hydrothermal method and applied for the photo-Fenton degradation of tetracycline (TC). The optimal Mn-FeWO₄-0.05 achieved 100% removal of TC within 60 min under visible light irradiation with a degradation rate constant of 0.0793 min⁻¹, which is 4.5 times higher than that of pristine FeWO₄. Systematic characterization revealed that Mn²⁺ ions were successfully incorporated into the FeWO₄ lattice, inducing lattice expansion and narrowing the bandgap from 2.37 eV to 2.25 eV, while also adjusting the conduction and valence band positions. This modulation significantly enhanced visible light absorption and promoted the separation and migration of photogenerated electron–hole pairs. In addition, the Mn²⁺/Mn³⁺ and Fe²⁺/Fe³⁺ dual redox cycles ensure the continuous generation of reactive oxygen species. Radical trapping experiments and electron paramagnetic resonance (EPR) spectroscopy demonstrated that superoxide radicals (•O₂⁻) and photogenerated holes (h⁺) were the dominant reactive species, while singlet oxygen (¹O₂) and hydroxyl radicals (•OH) played auxiliary roles. Moreover, Mn-FeWO₄-0.05 exhibited excellent stability, strong anti-interference ability against common anions, and high degradation efficiency toward various pollutants. Full article

Curcumin, a natural polyphenol derived from Curcuma longa, is widely recognized for its therapeutic properties. However, its clinical utility is limited because of poor solubility, rapid degradation and hence low bioavailability. To overcome these issues, nanoformulation approaches, especially PEGylated liposomes, have been explored as advanced delivery systems. PEGylation, which involves attaching polyethylene glycol (PEG) to the liposomal surface, enhances circulation time by creating a steric shield that reduces protein interactions and clearance by the mononuclear phagocyte system (MPS). However, PEG can alter lipid membrane properties, which may in turn affect curcumin’s solubility and distribution within the liposomal bilayer, ultimately reducing its loading efficiency. To ensure that PEG-modified liposomes can be effectively loaded with curcumin, we investigated curcumin–membrane interactions in saturated (DMPC) and unsaturated (POPC) liposomes, both in the presence and absence of PEG. Based on dissociation constants (K_d) obtained from fluorescence spectroscopy measurements, we found that PEGylated DMPC liposomes exhibit the strongest binding affinity for curcumin. Fluorescence quenching experiments showed that curcumin adopts a transbilayer orientation in all membranes examined. Curcumin’s location within PEGylated and non-PEGylated liposomal membranes was further confirmed by examining its effects on membrane properties, including fluidity, polarity, and oxygen transport. These effects were investigated using electron paramagnetic resonance (EPR) spectroscopy with spin labels. The results indicate that PEG does not impose major changes on membrane properties. Curcumin, however, was found to reinforce the liposomal membranes, increase their polarity, and reduce oxygen availability. Overall, the findings suggest that liposomes, particularly those composed of PEGylated DMPC, are effective vehicles for curcumin delivery. Full article

The exceptional stability of C-F bonds renders PFAS highly persistent in aqueous environments, posing significant challenges for conventional treatment technologies. While plasma-based technologies show promise, their efficiency is often limited by poor gas–liquid mass transfer in bulk liquid. Here, an in-house constructed ultrasonic atomization–dielectric barrier discharge (UEN-DBD) system was developed to promote PFAS degradation under non-thermal plasma conditions. Ultrasonic atomization generated microdroplets, which promoted PFAS enrichment at the surface of microdroplets and facilitate interactions with plasma-generated reactive species. Using perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) as model compounds, degradation behavior was evaluated over an initial concentration range of 0.01–1.0 ppm. At 0.01 ppm, degradation efficiencies of 96.06% for PFOA and 94.86% for PFOS were achieved within 5 min. Electron paramagnetic resonance (EPR) spectroscopy confirmed the formation of oxidative radicals (·OH) and suggested a mixed redox environment involving reactive species, potentially including superoxide (O₂·⁻) or hydrated electrons (e_aq⁻), in the discharge-treated system. High-resolution mass spectrometry results are consistent with a stepwise chain-shortening pathway dominated by successive –CF₂– scission, while fluoride-release measurements provided supporting evidence for partial defluorination. These findings advance the understanding of plasma-assisted PFAS degradation at the gas–liquid interface and provide a basis for the further development of plasma-assisted PFAS treatment strategies. Full article