Search Results (513)

The long-term preservation of historical documents in archival environments is critically challenged by the accumulation of hazardous gases—formaldehyde (HCHO), benzene (C₆H₆), and radon (Rn)—which originate from collection materials and pose severe health risks to personnel. In this work, we systematically investigate, via first-principles theory, the potential of Au- and Ru-doped PtSe₂ monolayers as resistive-type gas sensors for the detection of these pollutants. Atomic-scale substitutional doping at the Se site is modeled to establish the doped PtSe₂ configurations, and the structural stability, electronic properties, adsorption behavior, charge transfer characteristics, and recovery kinetics of the doped systems are comprehensively evaluated and compared. Our findings, through comprehensive comparison, reveal that Ru-PtSe₂ outperforms its Au-doped counterpart across all key performance metrics, positioning it as a promising candidate for hazardous gas monitoring in archival environments. The key innovation of this work lies in the systematic comparative assessment of noble metal dopants on PtSe₂ monolayers, identifying Ru as a superior choice to Au and providing a theoretical foundation for designing high-performance, recyclable 2D material-based gas sensors tailored for cultural heritage preservation applications. Full article

High-performance ammonia (NH₃) sensors play a critical role in environmental protection and noninvasive medical diagnosis. This work reports a new NH₃ sensor based on Au-microsphere-decorated polyaniline (PANI) manufactured by a precise in situ inkjet printing method on a MEMS micro-hotplate. The in situ oxidative polymerization of aniline was performed directly on the MEMS platform using AuCl₃ as a bifunctional oxidant and precursor, with a hierarchical morphology of microspheres (~750 nm) and nanorods (~250 nm). Reduced from Au³⁺ in the polymerization reaction, Au microparticles achieve substantial catalytic promotion by virtue of chemical sensitization and spillover effect. The optimized Au–PANI MEMS sensor exhibits a superlative response of 201% toward 1 ppm NH₃ at room temperature, with an ultra-low theoretical limit of detection (LOD) of 0.42 ppb. Furthermore, the device demonstrates rapid response/recovery kinetics (76 s/72 s), exceptional selectivity against common interfering gases (SO₂, CO, H₂, etc.), and robust long-term stability with high response retention over two months. This research provides a scalable, cost-effective strategy for the mass production of miniaturized, high-sensitivity gas sensors for industrial and healthcare applications. Full article

Despite decades of intervention efforts, mercury amalgamation remains widespread in artisanal gold mining (AGM), yet no prior study has presented an integrated metallurgical balance quantifying gold (Au), silver (Ag), and mercury (Hg) simultaneously across both the amalgamation and cyanidation stages of a single processing circuit. This study addresses this gap by evaluating an artisanal amalgamation–cyanidation operation in Pernambuco, Brazil, through systematic sampling, fire assay and ICP-OES analyses, grain size distribution, and SEM-EDS mineralogical characterization. The whole-ore amalgamation (WOA) stage recovered 44.7% ± 11.7% of Au and 11.5% ± 15.4% of Ag from a feed grading 2.96 ± 1.53 ppm Au and 8.09 ± 1.65 ppm Ag. Subsequent vat cyanidation of the Hg-contaminated tailings recovered 75.8% ± 4.32% of the remaining Au and 32.9% ± 9.24% of Ag, raising overall recoveries to 86.6% ± 2.89% for Au and 40.6% ± 4.58% for Ag. Although both stages contribute meaningfully to gold recovery, under the operating conditions evaluated, cyanidation contributed more substantially to overall Au recovery than whole-ore amalgamation. SEM-EDS identified free amalgamated electrum particles in the tailings, attributed to excessive pulp density (≈43% solids) impairing particle settling on the amalgamation plates. These inefficiencies led to estimated mercury losses of 262 g/day, yielding a Hg_(lost):Au+Ag_(produced) ratio of 5.5. Based on this diagnostic evidence, replacing whole-ore amalgamation with optimized comminution followed by gravity concentration is identified as a technically promising mercury-free pathway requiring pilot-scale validation. Full article

Acetamiprid (ACE) is a widely used neonicotinoid insecticide with potential health risks due to its persistence in the environment and bioaccumulation in plant-based foods. In this study, an improved dual-mode lateral flow immunochromatography assay (DMLFIA) was established for the sensitive detection of ACE residues in plant-based foods using Au@Ag@Pt NPs as dual-function signal probes. In the colorimetric mode (Mode 1), with the inhibition rate as the vertical coordinate and the ACE concentrations as the horizontal coordinate, the linear detection range of the colorimetric mode was 0.1–3000 μg/L with the detection limit of 0.08 μg/L. In the photothermal mode (Mode 2), the temperature values obtained via smartphones integrated thermal imager showed a linear relationship with 0.1–3000 μg/L of ACE, and the detection limit is 0.1 μg/L. The cross-reactivity rate of the developed DMLFIA with other structural analogs and functional substances was less than 0.39%. The recovery rate of the developed DMLFIA used in spiked plant-based foods was 81.1–99.4%, with relative standard deviations (RSD) of 1.3–10.7%. The detection results of this constructed DMLFIA showed good consistency with those obtained by HPLC and ELISA. The constructed DMLFIA provides a selective, sensitive and rapid detection tool for ACE in different scenarios in plant-based foods. Full article

Integrated circuits (ICs), a major fraction of waste electrical and electronic equipment (WEEE), represent an important secondary source of gold (Au). However, recovering high-purity Au from ICs remains challenging due to the high silicon dioxide content that encapsulates Au within the IC core and the presence of complex base-metal mixtures that hinder selective purification. This study proposes a simplified end-to-end process that integrates mechanical liberation, magnetic separation, oxidative chlorination, ion-exchange purification and Au recovery from isolated ICs. Unlike conventional multi-stage comminution routes, the proposed pretreatment combines hydraulic pressing, milling/sieving and magnetic separation to maximize Au exposure while minimizing dust generation, metal losses and base-metal interference, which is subsequently subjected to oxidative leaching and purification. Optimal extraction conditions, determined through a Taguchi design (2.5 M HCl, 0.34 M NaClO, 40 °C, solid–liquid ratio 1 g/40 mL, 3 h), achieved a Au leaching efficiency of 89%. The resulting multi-metal leachate was treated with a strong anionic ion-exchange resin, increasing Au purity from 8% to 86% after thiourea elution in a sulfuric-acid medium. Final Au recovery was completed by reductive precipitation with sodium borohydride, yielding complete solidification (~100% efficiency). A comparative life-cycle assessment showed that this recycling route offers favourable environmental performance relative to primary mining. Beyond achieving efficient Au recovery, this work establishes an integrated recovery route for isolated ICs that combines process simplification with environmental positive impact, addressing an important gap in WEEE recycling. Full article

As a core component of vitamin B12, Co²⁺ is closely associated with the health, life performance, and productivity of ruminants. Therefore, the selective and sensitive detection of Co²⁺ is of great significance. In this work, using the Au–S bond as an “anchor”, a ternary nanocomposite (CDs-AuNPs-GSH) with synergistic functions was constructed by combining gold nanoparticles (AuNPs) with glutathione (GSH) through hydrogen bonding and electrostatic interactions with functional groups on the surface of carbon dots (CDs). The resulting nanocomposite was employed as a fluorescence sensor for Co²⁺ detection. Under optimal conditions at pH 6.0, the sensor exhibited a good linear relationship over the Co²⁺ concentration range of 0.5–125.0 mM, with a limit of detection (LOD) of 0.38 mM. The interaction mechanism between Co²⁺ and the composite was systematically investigated using various characterization methods. The results indicated that Co²⁺, owing to its strong coordination ability, enriches on the surface of the composite, subsequently triggering dynamic fluorescence quenching via an electron transfer pathway. The sensor was successfully applied to determine Co²⁺ in mixed livestock and poultry feed samples, with recovery rates ranging from 89.4% to 103.9%, demonstrating its potential for on-site detection in feed analysis. Full article

Coal ash-slag waste from coal-fired power plants is a high-volume technogenic material whose resource potential is controlled by particle-size heterogeneity, mineralogical composition, and the occurrence modes of valuable elements. This study investigated Au occurrence in ash-slag waste derived from Ekibastuz coal and evaluated gravity–magnetic preconcentration as a diagnostic first stage for separating Au- and Fe-bearing products. The material was characterized by particle-size analysis, X-ray diffraction, chemical analysis, optical and electron-probe microscopy, atomic absorption analysis (AAS), kinetic spectral analysis (KSA), gravity concentration, and magnetic separation. The feed was an aluminosilicate–ferruginous material dominated by mullite, magnetite, quartz, and hematite. In the coarse material, liberated native Au co-reported with heavy Fe-bearing phases: the vibratory spiral concentrate contained 0.99 g/t Au and 39.00% Fe, corresponding to 52.58% Au recovery and 66.49% Fe recovery. The combined spiral and centrifugal concentrates yielded 1.04 g/t Au at 63.22% recovery, representing an approximately eightfold upgrade relative to the 0.13 g/t feed. In contrast, gravity recovery from the finest fraction was approximately 1%, indicating ultrafine, poorly liberated, or matrix-associated Au. KSA gave higher Au values than AAS, reflecting matrix heterogeneity and method-dependent preparation and detection effects rather than analytical superiority. The results support a size-selective gravity–magnetic preconcentration route followed by targeted mineralogical verification and product-specific downstream extraction. Full article

The presence of aflatoxin B1 (AFB1) is ubiquitous in the environment, and it is considered one of the most powerful natural carcinogenic substances. In this study, a highly sensitive electrochemical aptasensor was designed to detect aflatoxin B1 (AFB1) in peanuts. Iron–cobalt-doped magnetic carbon (Fe-Co/NPC) was used to enhance the conductivity of the electrode and catalytic performance, providing an increased specific surface area. Gold nanoparticles (AuNPs) were used to immobilize an aptamer. And cDNA-polyacrylic acid (cDNA-PAA) nanogels served as a high-density carrier for cDNA and an active signal amplification unit, significantly increasing the charge transfer resistance (Rct) through steric hindrance and electrostatic repulsion. Unlike traditional aptasensors that relied on passive blocking agents, we designed a competitive displacement mechanism. AFB1 competed with cDNA-PAA during detection in order to bind to the aptamer, which resulted in the removal of the non-conductive complex and a substantial increase in the electrochemical signal. Under the optimal conditions, the aptasensor had a linear response range of 1–1000 ng/L and a limit of detection (LOD) of 0.3 ng/L. It displayed high specificity, reproducibility, and stability. In spiked peanut samples, the recoveries ranged from 98.04% to 100.86%. Due to its sensitivity and reliability, this aptasensor has a great determination of AFB1 in food safety applications. Full article

2,4-Dichlorophenoxyacetic acid (2,4-D) is an extensively applied organic compound, primarily for agricultural weed control and plant growth agents. Although 2,4-D usually exists in the environment in low volumes, the detection of 2,4-D is critical for human health and environmental safety. In this work, a biophotonic biosensor was fabricated by coating the surface of a tapered optical fiber with gold nanoparticles (AuNPs) to excite the localized surface plasmon resonance (LSPR) and functionalizing the fiber with molybdenum disulfide nanosheets (MoS₂-NSs)/zinc oxide nanowires (ZnO-NWs) to extend the effective sensing area. Due to the inhibitory effect of 2,4-D on the hydrolytic activity of ALP, the refractive index (RI) around the sensor surface changes, leading to a shift in the LSPR peak wavelength. According to this sensing technique, the sensor can detect concentrations in the range of 1–10 mg/L, with a limit of detection (LOD) of 0.29 mg/L. The stability, repeatability and selectivity tests show that the sensor has good stability and selectivity. In the actual sample detection experiment, the recovery rates of apples and Chinese cabbage were 96.2–100.4% and 83.8–108.8%, respectively, which indicated that the detection method had good accuracy for the detection of target substances in actual samples. Thus, the proposed sensor has an important application in the detection of 2,4-D herbicides. Full article

Neuropeptide Y (NPY) is a stress-modulating neuropeptide and a promising biomarker for non-invasive assessment. Herein, a sensitive electrochemical aptasensor was developed on reduced graphene oxide/gold nanoparticle (rGO/AuNP)-modified screen-printed electrodes for selective NPY detection. A methylene blue (MB)-labeled NPY-specific aptamer was immobilized on the electrode surface through Au–S chemistry, and square-wave voltammetry (SWV) was used for signal readout. The rGO/AuNP-modified interface provided high conductivity and a large effective surface area, facilitating electron transfer and probe immobilization. Under optimized conditions, the aptasensor exhibited a linear detection range of 10–10,000 pg mL⁻¹ in PBS with a low detection limit of 1.17 pg mL⁻¹ and good linearity (R² = 0.991). In addition, the sensor showed satisfactory selectivity, reproducibility, and mechanical stability. Recovery tests in artificial sweat yielded recoveries of 91.8–107.8% with relative standard deviations below 5%, demonstrating good analytical accuracy in complex matrices. Combined with an agarose-hydrogel-assisted sampling interface and a reverse-iontophoresis-compatible wearable platform, this low-cost and facile sensing strategy provides a portable proof-of-concept approach for NPY analysis in artificial sweat and shows potential for future wearable-oriented biofluid monitoring. Full article

Anti-UAV multi-object tracking in remote sensing videos is challenging because UAV targets are small, weakly textured, and often affected by cluttered backgrounds, abrupt motion, occlusion, and intermittent visibility. To address these challenges, we formulate anti-UAV multi-object tracking as a context-aware identity prediction task, in which target identities and locations are inferred from historical trajectory priors instead of current-frame observations alone. Under this formulation, we propose a dual-track parallel tracking framework. The adaptive identity disambiguation (AID) module combines motion cues with appearance features according to their estimated reliability, improving short-term association when visual evidence is weak. In parallel, the motion-evolution temporal memory (METM) module models trajectory dynamics using motion anomaly detection and time-decayed memory, enabling spatiotemporal recovery after occlusion, temporary disappearance, or abrupt motion. The outputs of the two branches are integrated by a unified identity decision layer to produce stable tracking results. Experiments are conducted on the public 4th Anti-UAV Benchmark Track-3 and our newly constructed Anti-UAV Multi-Object Tracking dataset, AU-MOT. On the 4th Anti-UAV Benchmark Track-3, our method achieves 63.6% HOTA and 64.1% IDF1, outperforming the strongest competing method by 3.5% and 3.9%, respectively, while reducing identity switches and track fragments by 20.8% and 23.8%. On AU-MOT, it achieves 67.2% HOTA and 67.8% IDF1, with 20.2% fewer identity switches and 22.3% fewer track fragments. These results demonstrate its effectiveness under long-range observation, weak target appearance, cluttered backgrounds, abrupt motion, and intermittent target visibility. Full article

The thiourea grafting method can effectively improve the ability of activated carbon to recover chloroauric acid (AuCl₄⁻). Conventional grafting strategies rely on acyl halide reactions using reagents such as SOCl₂ and CH₂Cl₂, which suffer from instability and high toxicity. Herein, we propose a green grafting strategy for thiourea by activating carboxyl groups with EDC-HCl/NHS in acetonitrile, followed by the amidation reaction to obtain thiourea-modified carbon (AC-NCS). FT-IR and XPS analyses confirm the successful grafting of thiourea onto the activated carbon surface. Compared with pristine activated carbon, the adsorption capacity of AC-NCS is 104.8 mg/g, increased by 5.76 times. Furthermore, it maintains a recovery rate of 84.2% after three cycles. XPS and FT-IR further reveal that adsorption occurs on the thiourea sulfur atoms (C=S) and protonated primary amines(-NH₃⁺), and the recovery of chloroauric acid is achieved through a synergistic “reduction–electrostatic attraction” mechanism. This method reduces the dependence on highly toxic reagents and provides a promising approach for the efficient and green recovery of gold from secondary resources. Full article

The valorization of salmon farming by-products is an essential strategy within the circular economy. This study optimized the enzymatic hydrolysis of salmon frame proteins using Alcalase 2.5L and response surface methodology (RSM). The effects of temperature (50–60 °C), substrate concentration (50–100% w/w), and protease dose (1–13 mAU/g salmon frames) were evaluated on two key responses: degree of hydrolysis (DH) and nitrogen recovery (NR). The 20 experimental assays showed that substrate concentration and enzyme dosage strongly influenced both responses, whereas temperature had a moderate effect. The fitted models exhibited R²_adjusted values above 70% and met statistical assumptions, confirming their predictive reliability. Optimal conditions for maximizing DH were 55 °C, 50% w/w substrate, and 13 mAU/g protease, yielding a predicted DH of 6.65%. In contrast, the highest NR (48.35%) was observed at 50 °C, 50% w/w substrate, and 13 mAU/g protease, indicating that solubilization does not depend solely on hydrolysis intensity. Validation experiments showed no significant differences between predicted and experimental values (p > 0.05), supporting the robustness of the models. These results demonstrate the usefulness of RSM for optimizing enzymatic hydrolysis and advancing sustainable valorization of salmon by-products. Full article

There is increasing interest in structured layered double hydroxide (LDH)-based catalysts because they combine tunable acid–base/redox chemistry with reactor architectures that can reduce diffusion lengths, improve heat management, and lower pressure-drop penalties. This review evaluates LDH, LDH-derived oxide (LDO/MMO), reduced metal/LDO, reconstructed hydroxide-rich, and mixed dynamic states integrated into honeycomb monoliths, open-cell foams, meshes/felts, thin films, washcoats, coated plates, microchannels, capillaries, and additively manufactured lattices. To move beyond descriptive comparison, the literature is assessed using unified evaluation dimensions: operative active state, support architecture, coating/integration route, active-phase loading, coating thickness and uniformity, reactor-volume-normalized productivity or STY, ΔP/L, axial/radial thermal gradients, time-on-stream, coating loss, regeneration recovery, and pilot-readiness. Representative benchmarks illustrate both the promise and reporting gaps of the field: NiFe-LDH-derived monoliths for CO₂ methanation have reached ~70% CO₂ conversion at 300 °C with >90% CH₄ selectivity and only 0.7% post-test mass loss; NiFe-LDH/iron-foam monoliths retained 85% ozone conversion after 168 h; high-entropy LDH-derived oxides showed T50/T90 values of 246/254 °C for toluene oxidation; and Au/LDH capillary films achieved 31.9% glycerol carbonate yield and 3.78 g h⁻¹ g⁻¹ productivity. The strongest current cases are pollution abatement and CO₂ methanation, whereas biomass upgrading, fine-chemical flow, high-entropy coatings, and photo/electrocatalytic films require deeper module-level validation. Overall, structured LDH catalysts should be treated as coupled chemistry–coating–reactor systems whose performance must be judged simultaneously by activity, accessible catalyst inventory, transport efficiency, pressure drop, thermal profile, durability, regeneration, and manufacturability. Full article

Background: Mixed martial arts (MMA) involve repeated high-intensity, explosive actions that cause substantial fatigue, underscoring the importance of effective recovery strategies. Purpose: This pilot study investigated short-term performance responses to different post-exercise recovery interventions in Polish MMA athletes. Methods: Sixteen athletes (14 males and 2 females) were randomly assigned to cryosauna (CRYO), cold-water immersion (CWI), foam rolling (FR), or passive recovery (CON), with 4 participants per group. The intervention lasted two weeks, with the assigned recovery intervention applied after each training session. Performance was evaluated before and after the intervention using the countermovement jump (CMJ), isokinetic knee peak torque (flexion and extension), and reactive stress tolerance of the determination test (DT). Data were analyzed using mixed-design ANOVA. Results: CMJ performance improved over time across groups. FR significantly increased knee extension (from 228.67 ± 26.49 N.m to 250.50 ± 22.41 N.m), whereas DT scores significantly increased in the CRYO group (from 247.50 ± 12.50 AU to 291.50 ± 15.61 AU) and significantly decreased in the CON group (from 290.25 ± 24.45 AU to 255.50 ± 24.18 AU). Significant Time × Group interactions were observed for DT (p < 0.001) and knee extension torque (p = 0.008). Conclusions: FR appeared beneficial for knee extension performance, whereas CRYO was associated with improved DT performance. Findings are exploratory and need confirmation in larger, controlled studies. Full article