Search Results (424)

Ferroelectric (FE) diodes configured in the metal–ferroelectric–metal (MIFM) structure are promising candidates for non-volatile memory. While recent studies emphasized bulk FE properties, interfacial characteristics have not been carefully considered. In this work, we investigate the HfO₂/Al_0.8Sc_0.2N interface by examining its impact on switching and rectifying characteristics in MIFM FE diodes with variable HfO₂ thicknesses (2/4/6 nm). Electrical characterization reveal that the increased HfO₂ thickness raises the coercive field (E_C) due to enhanced electrostatic effects and progressive interfacial oxidation from Sc-N to Sc-O bonds. This resulting oxygen substitutional defect (O_N) which may contribute to domain-wall pinning and reduced rectifying efficiency. Cycling tests clarify operating regime-dependent phenomena, including O_N redistribution-induced wake-up and eventual breakdown. Moreover, enhanced retention is observed after pre-cycling, originating from the stabilization of the interfacial defects rather than bulk properties. These findings underscore that E_C and device reliability are likely influenced by interfacial engineering, which is critical for the reliable operation of AlScN-based FE diodes. Full article

Efficient monitoring of pork freshness is essential to minimize spoilage-related losses in the meat industry. To address the limitations of existing detection technologies, namely high cost, poor timeliness and high environmental sensitivity, this study developed a novel electronic nose system integrating a hybrid sensor array with dynamic gas path control. By combining metal oxide semiconductor (MOS) and electrochemical sensors (e.g., MQ137, MQ136), the system exhibits high sensitivity to the key volatile organic compounds (VOCs) released during pork spoilage, achieving a detection accuracy of over 90% in identifying spoilage stages. Combined with a dual-mode gas circuit design (solenoid valve switching time: 0.85 s), the reliability of the system was further demonstrated. This technology offers an economical and efficient real-time monitoring solution for slaughterhouses and cold chain logistics, providing a new low-cost scientific approach for pork freshness assessment. Full article

Mercury (Hg) is a global pollutant that poses a serious threat to ecosystems and human health. Biochar has shown great potential for mercury removal due to its porous structure and abundant surface functional groups. However, redox-active moieties on biochar can reduce adsorbed Hg²⁺ to volatile Hg⁰, leading to secondary mercury dispersion. To suppress this reduction, this study proposes a strategy of co-pyrolyzing coal gangue with rice husk to prepare composite biochars (RHB/CG), leveraging the abundant metal oxides in coal gangue to tailor the surface chemistry of biochar. The materials were characterized by FTIR, Raman, and XRD; static adsorption, mercury speciation analysis, and kinetic experiments were conducted. The results show that coal gangue incorporation significantly enhances the Hg²⁺ adsorption capacity of biochar, with the equilibrium adsorption capacity calculated by the pseudo-second-order kinetic model, increasing from 20.6 mg/g for pristine RHB to 38.7 mg/g for RHB/CG-1:1. More importantly, RHB/CG composites effectively suppress the reduction of Hg²⁺ to Hg⁰, and the amount of Hg⁰ accumulated in the system is 57.1% lower than that of pristine RHB. Mechanistic studies reveal that coal-gangue-derived basic functional groups (e.g., C–O–C, Si–O–M) inhibit reduction via sequestering Hg²⁺ through coordination and disruption of electron transfer pathways. PHREEQC simulations (pe = 6.0) confirm the decreased tendency of Hg²⁺ reduction to Hg⁰ with increasing pH, in good agreement with the experimental results showing reduced Hg²⁺ reduction. The corresponding results provide a green and sustainable solution for mercury-contaminated water and soil remediation. Full article

Black tea quality is governed by aroma chemistry: terpene alcohols (linalool, geraniol, nerolidol), methyl salicylate, and short-chain aldehydes whose abundance and release kinetics from the polyphenol-rich leaf matrix shape perceived grade. Grade information lies not only in the average headspace concentration but in the temporal shape of volatile organic compound (VOC) release under controlled heating. Conventional electronic noses obscure this signal: they rely on multi-sensor arrays, compress each response into summary statistics, and report accuracy only at the level of individual measurements. Whether a single low-cost metal–oxide–semiconductor (MOS) gas sensor can recover grade-defining aroma chemistry, and whether waveform-level modeling can exploit it, was therefore investigated. A portable electronic nose built around a Bosch BME688 sensor recorded 90 time series, each comprising four directly measured channels (temperature, humidity, pressure, gas sensor resistance) and a derived indoor-air-quality (IAQ) proxy computed from them by the on-chip BSEC library, from 16 commercial Turkish black teas across three quality grades. Two representations were compared on the same data: a feature-based pipeline reducing 25 statistical descriptors to seven principal components for six classifiers (best F1-macro = 0.624, MLP), and a raw-waveform Multi-Scale 1D-CNN with Squeeze–Excitation and temporal self-attention (MS-CNN-Attention). Under product-grouped cross-validation, the deep model reached F1-macro = 0.811 (+30%) and graded 14 of 16 products correctly by majority vote, against 11 of 16 for the MLP, with the largest gain in the medium grade (F1: 0.52 → 0.79), where summary-statistic compression destroys the release-kinetic signal. The contributions are threefold: one programmable MOS sensor operated as a thermal-desorption profiler rather than a sensor array; a direct comparison of feature-based classical learning against raw-waveform deep learning on the same small, non-normally distributed dataset; and a product-level decision-consistency metric suited to batch screening. Pairing a low-cost MOS sensor with waveform-level modeling offers a rapid, non-destructive route to aroma-chemistry-based tea quality screening. Full article

This study investigates the effect of sintering temperature on the hot-corrosion behavior of Ti-6Al-4V alloy in a molten salt environment. Samples were sintered at 800 °C, 900 °C, 1000 °C and 1100 °C, then exposed to the Na₂SO₄—25%NaCl for 300 h at 650 °C. The corrosion kinetics were evaluated by measuring the mass change in the specimens, and the results were correlated with their corresponding corrosion rates. The results show that the sintering temperature drives corrosion kinetics by influencing the sample density and grain size. The sample sintered at 900 °C shows a low corrosion rate due to its refined microstructure. This refined microstructure provides a high grain boundary density, which serves as a diffusion path and enables the formation of a dense, protective Al₂O₃–TiO₂ layer, as confirmed by XPS. In contrast, the sample sintered at 800 °C exhibits high porosity, resulting in an initial weight loss due to molten-salt penetration and evaporation of volatile metal chlorides. The samples sintered at 1000 °C and 1100 °C exhibit coarsened grains, leading to a thicker, brittle oxide layer and severe delamination, which in turn result in high corrosion rates. The results show that optimizing the sintering temperature to around 900 °C would enhance hot-corrosion resistance in salt-contaminated environments. Full article

The use of insect-based protein sources in aquaculture is gaining increasing attention with Hermetia illucens (black soldier fly, BSF) larvae meal representing a promising substitute to fishmeal (FM). This study evaluated the effect of partial dietary inclusion of BSF meal (BSF0, BSF2.5, BSF5, BSF10%) on the volatilome of rainbow trout (Oncorhynchus mykiss) fillets, before and after cooking, using gas chromatography–mass spectrometry (GC–MS) and a metal oxide sensor-(MOX)-based device. Fish were fed diets with increasing BSF inclusion, and both raw and cooked fillets were analyzed to assess changes in volatile organic compounds (VOCs). GC–MS enabled the identification and semi-quantitative analysis of VOC classes, while MOX sensor responses were processed using Linear Discriminant Analysis (LDA) to assess discrimination among dietary treatments. Results showed that BSF inclusion influenced the volatile profile, with clearer separation at higher inclusion levels (BSF5–BSF10%), especially in cooked fillets. Thermal processing enhanced these differences. GC–MS analysis revealed a reduction in aldehydes and ketones and an increase in carboxylic acids with higher BSF inclusion. Key compounds such as hexanal and heptanal decreased, indicating changes in lipid-derived volatile pathways. Overall, the integration of GC–MS and MOX sensors proved effective in detecting diet-induced changes, supporting their application as effective and reliable tools for quality assessment in aquaculture products, with potential implications for sensory quality that should be further confirmed through dedicated sensory studies. Full article

Triethylamine (TEA), a widely used volatile organic compound (VOC), poses severe threats to environmental safety and human health upon accidental leakage, making the development of high-performance TEA detection techniques urgently needed. Herein, we report a Sn-based metal–organic framework (Sn-MOF) constructed from 4,5-dichloroimidazole ligands synthesized via a solvothermal approach. The resulting MOF-derived SnO₂ materials were obtained by calcination at 400–600 °C, yielding SnO₂ with tunable specific surface area and surface defect-site density. Structural and surface characterizations revealed that the materials consist of primary nanoparticles in the range of 10–50 nm, forming aggregated particles of 1–2 µm. The gas sensing performance toward TEA was systematically evaluated. The SnO₂-400 °C sensor exhibited the highest response (S = 85.0) to 100 ppm TEA at 190 °C, with a low detection limit of 1 ppm, superior selectivity, good repeatability, and excellent long-term stability. The observed performance variation was attributed to the combined effects of specific surface area, abundant defect-associated surface sites, and suitable mesoporous structure. This work not only provides a high-performance TEA sensor for industrial and food safety monitoring but also offers a rational strategy for designing MOF-derived metal oxide gas sensors with tailored microstructures and surface defect chemistry. Full article

Essential oils (EOs) are widely studied as natural antimicrobial and antioxidant agents in food systems. However, their high volatility, low water solubility, instability, phytotoxicity, and strong aroma often limit their consistent applicability for food preservation. This review critically examines the literature and synthesizes current essential oil stabilization and delivery strategies in food systems, integrated with a bibliometric analysis of Scopus-indexed literature published before June 2025. The bibliometric findings showed an expanding research field, supported by 543 authors and 54 journals, revealing the disciplinary diversity of research on essential oil-based preservation systems. In addition, the review highlights a significant focus of studies on nanoemulsions, encapsulation, and active packaging in essential oil applications. Interestingly, the study also reveals the emergence of non-contact, or vapor-phase, technologies with improved release management. Furthermore, the review shows that essential oils’ functionality depends not only on major bioactive compounds but also on chemical class, oxidative sensitivity, release behavior, interactions with the food matrix, and the delivery platform. Mechanistically, stabilization technologies such as emulsions, encapsulation, and coatings/films can improve the protection, dispersion, and release of essential oils; however, their effectiveness strongly relies on formulation variables, matrix composition, and the regulatory framework. Emerging platforms such as nanofibers, zeolites, and metal–organic frameworks offer promising routes for vapor-phase or non-contact delivery systems, ensuring improved release control, functionality, and sensory quality, but may be limited by their scalability and production cost. However, a major research gap identified by this review is the imbalance between extensive “in vitro” studies and limited studies on real food matrices, which impedes understanding of the impacts of food matrices and packaging materials on essential oil release kinetics, antimicrobial efficacy, and sensory quality. Therefore, future research should integrate real-food applications, consumer acceptability, shelf-life performance, release-kinetic modeling, and techno-economic analysis to advance essential-oil-based technologies in food systems. Full article

Non-invasive blood glucose estimation from exhaled breath has been proposed as a painless alternative to repeated capillary measurements; however, performance evaluation remains challenging in small-sample settings. This study investigates the estimation of blood glucose from human breath using volatile organic compound (VOC) signals acquired with an electronic nose. Responses from three metal-oxide sensor channels sensitive to CO, alcohol, and acetone were collected from 58 individuals, with one measurement per subject, and analyzed using strictly patient-level five-fold cross-validation, in which test folds comprised only real subjects. Two experimental factors were examined. First, model performance was evaluated with and without an additional interpretable alcohol–acetone log-ratio capturing relative variation between compounds. Second, model training was performed using either real data only or fold-wise tabular synthetic augmentation generated via a Gaussian copula fitted exclusively on training subjects, while evaluation remained strictly real-only. Under real-only training, classical machine learning models achieved the lowest prediction errors (approximately 6–7 mg/dL), whereas under synthetic augmentation FTTransformer was the best-performing deep learning model. This findings should be understood as a constrained proof-of-concept analysis rather than as evidence of diagnostic capability or clinical readiness. Full article

Volatilization of alloying elements during vacuum refining of high-Cr die steel can cause fume generation, resource loss and increased dust-collection burden. Here, D2 high-carbon high-chromium die steel was melted in a vacuum induction furnace and held at 15 Pa and 1600 °C for 60 min, while CO and CO₂ evolution was monitored online. The collected volatile matter and the used magnesia crucible were characterized by XRF, XRD, Micro-CT, SEM-EDS, and XPS. The volatile matter mainly consisted of Fe-Cr-Mn metallic solid-solution phases and nanoscale agglomerates with partial surface oxidation. XRF results showed that the collected metallic volatile matter contained 49.96 wt.% Mn, 32.58 wt.% Fe, and 13.23 wt.% Cr. The enrichment factors of Cr and Mn relative to Fe were calculated to be 2.78 and 3.91 × 10², respectively, indicating strong selective volatilization of Mn. Micro-CT revealed that the deposition layer was confined to the inner surface of the upper crucible, while the bulk MgO crucible remained dense. Thermodynamic calculations showed that at 10 Pa, the calculated volatilization amounts of Fe, Cr, and Mn reached 3.32 g, 1.05 g, and 0.31 g per 100 g of molten steel, respectively, whereas element volatilization was markedly suppressed when the pressure was increased. A vacuum level above 20 Pa is therefore proposed as a practical process window to reduce fume generation and alloy loss during vacuum processing of high-Cr die steels. Full article

Environmental toxicants may affect the height of children and adolescents. However, studies on the toxicological effects based on extensive internal exposure omics are still lacking. This study aimed to identify key toxicants associated with height and assess the mediating role of sex steroid hormones. To this end 1660 participants aged 6–19 years from subsample A in the National Health and Nutrition Examination Survey (NHANES) were included. Exposome was characterized by 58 toxicants within 12 families. After assessment by the exposome-wide association analysis and mixture models, we identified 17 toxicants inversely associated with height-for-age Z-scores (HAZ), predominantly metals and volatile organic compound (VOC) metabolites. Tin exhibited the strongest inverse association (β = −0.261), followed by lead (β = −0.230). The primary contributors to reduced height included tin, lead, the VOC metabolite 2-ATCA, ethylene oxide, and nitrate. Notably, males and younger children were the more susceptible subgroups. Furthermore, mediation analysis revealed that sex steroid hormones, particularly total testosterone and estradiol, mediated 8% to 37% of the associations. These findings suggest that endocrine-related pathways may link toxicant exposure to impaired linear growth, highlighting the necessity of reducing exposure during childhood. Full article

Volatile organic compounds (VOCs) represent a significant threat to both environmental quality and public health, driving the need for efficient abatement technologies. Herein, a series of PdCu dual single-atom catalysts supported on peroxide-modified attapulgite (ATP) were synthesized via a microwave-assisted solvothermal approach, and the effect of the Pd/Cu ratio on the catalytic oxidation of toluene was investigated. Results showed that the Pd1Cu1/ATP catalyst exhibited exceptional catalytic performance, achieving 99% toluene conversion at 240 °C under a high weight hourly space velocity of 20,000 mL·g⁻¹·h⁻¹. This high efficiency is attributed to the modification of ATP with hydrogen peroxide solution, which exposes abundant Si-OH, facilitating the immobilization of atomically dispersed atoms and enhancing the adsorption of toluene molecules. In addition, the strong metal–support interaction between the PdCu dual atoms and the ATP support significantly lowers the energy barrier of the reaction, thereby enhancing the low-temperature catalytic activity. In situ DRIFTS further elucidated the reaction pathway and intermediate evolution during toluene oxidation. This work offers an effective strategy for designing highly efficient dual single-atom catalysts for VOCs removal. Full article

The integration of non-thermal plasma (NTP) with heterogeneous catalysis has emerged as a promising strategy for the efficient abatement of industrial volatile organic compounds (VOCs), overcoming key limitations of conventional thermal and standalone plasma technologies. This review provides a comprehensive overview of the synergistic mechanisms in NTP-catalytic systems, with particular emphasis on the bidirectional interactions between plasma and the catalyst. Specifically, plasma can activate catalysts through surface defect generation and improved metal dispersion, while catalysts, in turn, modulate plasma characteristics via localized electric field enhancement and electron energy redistribution. Furthermore, this synergy spans multiple spatiotemporal scales, linking ultrafast electron dynamics with macroscopic catalytic performance, and atomic-scale active sites with reactor-level behavior. Based on these mechanistic insights, rational catalyst design strategies are systematically discussed, including transition metal oxides, noble metals, perovskites, and metal–organic frameworks. Finally, key challenges related to catalyst deactivation, energy efficiency, and process scalability are highlighted. Future perspectives are proposed, focusing on advanced in situ diagnostics and AI-assisted material discovery to accelerate the practical implementation of NTP-catalytic technologies for sustainable VOC removal. Full article

The development of novel information-functional devices based on emergent physical phenomena is crucial for integrated circuit technology in the post-Moore era. Two-dimensional magnetic materials present an ideal platform for spintronic devices; however, regulating their room temperature magnetism poses significant challenges. Traditional methods like ionic liquid gating and strain control face issues such as poor stability and complex processes, complicating compatibility with standard silicon technology. Here, we demonstrate a straightforward and robust approach for dielectric layer-engineered room temperature ferromagnetism in 2D metallic magnets by leveraging metal–insulator–semiconductor (MIS) structures. Using surface-oxidized Fe₃GeTe₂ as a model system, we systematically investigate how SiO_x dielectric layer thickness (50–300 nm) modulates magnetic properties. Thin dielectric layers significantly enhance room temperature ferromagnetism through boosted interfacial charge transfer, whereas thick layers maintain the material near its intrinsic state due to dielectric screening effects. Furthermore, reversible optical modulation of magnetism is achieved under ultraviolet illumination, with photoresponse capability diminishing as dielectric thickness increases. This work establishes a scalable, silicon-compatible strategy for controlling 2D magnetism and provides critical insights for developing optically tunable spintronic devices and non-volatile memory applications. Full article

Red mud (RM), a metal oxide-rich solid waste, was subjected to three different acid treatments to evaluate its catalytic performance in toluene oxidation. The acetic acid-modified red mud (HAC-RM) demonstrated excellent catalytic activity, achieving complete toluene conversion at 450 °C. XRD, XRF, N₂-BET and SEM results show acetic acid treatment can effectively remove pore-blocking inert components such as Na₂O and CaO, thus increased the Fe₂O₃ content, and significantly enhanced both the specific surface area and pore size of the catalyst. Furthermore, this modification enhanced reducibility and generated additional oxygen vacancies, verified by H₂-TPR and O₂-TPD, thereby improving the overall catalytic performance. In contrast, oxalic acid treatment under ultraviolet irradiation led to the formation of calcium carbonate via reaction with Ca²⁺ ions in RM, which resulted in reduced catalytic activity. To further enhance performance, MnO₂ was loaded onto the modified HAC-RM via an impregnation method to develop a low-cost and highly active catalyst. Among the prepared samples, 20%MnO₂/HAC-RM exhibited the highest catalytic efficiency, achieving 100% toluene conversion at 300 °C. XPS, H₂-TPR, and O₂-TPD results indicate the synergistic interaction between Fe₂O₃ and MnO₂ facilitated electron transfer and enhanced surface oxygen mobility. Additionally, the catalytic oxidation mechanism of 20% MnO₂/HAC-RM was elucidated. A detailed reaction pathway for toluene degradation is proposed by in situ DRIFT, as follows: toluene → benzyl alcohol → benzaldehyde/benzoyl peroxide → benzoate → CO₂ and H₂O. These findings are expected to contribute to the development of efficient, sustainable, and cost-effective catalysts for volatile organic compound (VOC) abatement. Full article