Search Results (850)

The development of cost-effective and highly sensitive hydrogen peroxide (H₂O₂) biosensors with robust stability is critical due to the pivotal role of H₂O₂ in biological processes and its broad utility across various applications. In this work, porous ceria hollow microspheres (CeO₂-phm) were synthesized using a solvothermal synthesis method and employed in the construction of an electrochemical biosensor for H₂O₂ detection. The resulting CeO₂-phm featured a uniform pore size centered at 3.4 nm and a high specific surface area of 168.6 m²/g. These structural attributes contribute to an increased number of active catalytic sites and promote efficient electrolyte penetration and charge transport, thereby enhancing its electrochemical sensing performance. When integrated into screen-printed carbon electrodes (CeO₂-phm/cMWCNTs/SPCE), the CeO₂-phm/cMWCNTs/SPCE-based biosensor exhibited a wide linear detection range from 0.5 to 450 μM, a low detection limit of 0.017 μM, and a high sensitivity of 2070.9 and 2161.6 μA·mM⁻¹·cm⁻²—surpassing the performance of many previously reported H₂O₂ sensors. In addition, the CeO₂-phm/cMWCNTs/SPCE-based biosensor possesses excellent anti-interference performance, repeatability, reproducibility, and stability. Its effectiveness was further validated through successful application in real sample analysis. Hence, CeO₂-phm with solvothermal synthesis has great potential applications as a sensing material for the quantitative determination of H₂O₂. Full article

We report a rapid aqueous method for synthesizing monodisperse gold nanoparticles (AuNPs), employing 2-propynylamine as both an intrinsic reducing agent and a surface-stabilizing ligand. This self-mediated process—achieved in a single step—yields spherical AuNPs with an average diameter of 4.0 ± 1.0 nm and a well-defined localized surface plasmon resonance band centered at 520 nm. Acting as a bifunctional molecule, 2-propynylamine simultaneously reduces HAuCl₄·3H₂O to elemental gold and passivates the nanoparticle surface through coordination via the amine group, while preserving a terminal alkyne (–C≡CH) functionality. This reactive moiety remains exposed and chemically accessible, enabling post-synthetic modification through Cu(I)-catalyzed azide–alkyne cycloaddition. Control experiments using alternate milling times and vial composition confirmed the essential role of 2-propynylamine in mediating both reduction and surface functionalization. The resulting alkyne-functionalized AuNPs serve as versatile “click-ready” platforms for bioconjugation, sensing, and advanced material assembly. Overall, this scalable, green approach eliminates the need for external reducing or capping agents and provides a modular route to chemically addressable nanomaterials with tunable surface reactivity. Full article

This study examines the effects of laser pulse duration on the structural, morphological, optical, and gas-sensing characteristics of ${\mathrm{Al}}_2{\mathrm{O}}_3$/AgO thin films deposited on glass substrates using pulsed laser deposition (PLD). Pulse durations of 10, 8, and 6 nanoseconds were achieved through optical lens modifications to control both energy density and laser spot size. X-ray diffraction (XRD) and atomic force microscopy (AFM) analyses showed a distinct reduction in both crystallite and grain sizes with decreasing pulse width, along with significant improvements in surface morphology refinement and film compactness. Hall effect measurements revealed a transition from n-type to p-type conductivity with decreasing pulse width, demonstrating increased hole concentration and reduced carrier mobility attributed to grain boundary scattering. Furthermore, current-voltage (I-V) characteristics demonstrated improved photoconductivity under illumination, with the most pronounced enhancement observed in samples prepared using longer pulse durations. Gas sensing measurements for ${\mathrm{NO}}_2$ and ${\mathrm{H}}_2$S revealed enhanced sensitivity, improved response/recovery characteristics at 250 °C, with optimal performance achieved in films deposited using shorter pulse durations. This improvement is attributed to their larger surface area and higher density of active adsorption sites. Our results demonstrate a clear relationship between laser pulse parameters and the functional properties of ${\mathrm{Al}}_2{\mathrm{O}}_3$/AgO films, providing valuable insights for optimizing deposition processes to develop advanced gas sensors. Full article

Precision and real-time detection of hydrogen peroxide (H₂O₂) are essential in pharmaceutical, industrial, and defence sectors due to its strong oxidizing nature. In this study, silver (Ag)-doped CeO₂/Ag₂O-modified glassy carbon electrode (Ag-CeO₂/Ag₂O/GCE) has been developed as a non-enzymatic electrochemical sensor for the sensitive and selective detection of H₂O₂. The synthesized Ag-doped CeO₂/Ag₂O nanocomposite was characterized using various advanced techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). Their optical, magnetic, thermal, and chemical properties were further analyzed using UV–vis spectroscopy, electron paramagnetic resonance (EPR), thermogravimetric-differential thermal analysis (TG-DTA), and X-ray photoelectron spectroscopy (XPS). Electrochemical sensing performance was evaluated using cyclic voltammetry and amperometry. The Ag-CeO₂/Ag₂O/GCE exhibited superior electrocatalytic activity for H₂O₂, attributed to the increased number of active sites and enhanced electron transfer. The sensor displayed a high sensitivity of 2.728 µA cm⁻² µM⁻¹, significantly outperforming the undoped CeO₂/GCE (0.0404 µA cm⁻² µM⁻¹). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 6.34 µM and 21.1 µM, respectively, within a broad linear detection range of 1 × 10⁻⁸ to 0.5 × 10⁻³ M. The sensor also demonstrated excellent selectivity with minimal interference from common analytes, along with outstanding storage stability, reproducibility, and repeatability. Owing to these attributes, the Ag-CeO₂/Ag₂O/GCE sensor proved effective for real sample analysis, showcasing its potential as a reliable, non-enzymatic platform for H₂O₂ detection. Full article

Multifunctional phosphors that integrate optical temperature measurement and counterfeit detection capabilities have garnered considerable interest owing to their diverse application potential. In this study, novel CaLaLiTeO₆:Mn⁴⁺/Er³⁺ phosphors were prepared via the high-temperature solid-phase method. The phase structure and morphology characterization confirmed the successful synthesis of CaLaLiTeO₆ material with effective doping of Mn⁴⁺ and Er³⁺ into the host lattice. Upon excitation at 379 nm, the CaLaLiTeO₆:Mn⁴⁺/Er³⁺ material exhibits far-red emission at 716 nm (Mn⁴⁺:²E_g → ⁴A_2g) and green emission at 525/548 nm (Er³⁺:²H_11/2/⁴S_3/2 → ⁴I_15/2). The emission peak intensities of Er³⁺ and Mn⁴⁺ ions in the CaLaLiTeO₆:0.015Mn⁴⁺/0.01Er³⁺ sample displayed distinct variations with temperature under different excitation wavelengths (325 nm, 379 nm, and 980 nm). Subsequently, a dual-mode optical temperature sensing system was developed based on the fluorescence intensity ratio and the dual excitation single-band ratiometric method, which achieved a maxed relative sensitivity of 1.12% K⁻¹ at 343 K. Moreover, the excitation-dependent luminescence color changes of CaLaLiTeO₆:Mn⁴⁺/Er³⁺ make it particularly suitable for anti-counterfeiting applications. The present study underscores the dual-functional capabilities in sophisticated non-contact optical temperature measurement and anti-counterfeiting applications. Full article

Precise remote temperature sensing at the micro- and nanoscale is a growing necessity in modern science and technology. We report a series of luminescent tris-acetylacetonate lanthanide complexes, Ln(acac)₃(H₂O)₂ (Ln = Eu (1Eu), Tb (1Tb), Yb (1Yb)); acac⁻ = acetylacetonate), operating as self-referenced thermometers in the 290–350 K range, both in the solid state and when embedded in hybrid nanoparticles. Among the investigated systems, the Eu³⁺ complex exhibits excellent lifetime-based thermometric performance, achieving a maximum relative sensitivity (S_rmax) of 2.9%·K⁻¹ at 340 K with a temperature uncertainty (δT) as low as 0.02 K and an average temperature uncertainty ($\overline{\delta T}$) of 0.5 K, placing it among the most effective ratiometric lanthanide-based luminescent thermometers reported to date. The Yb³⁺ analog enables intensity-based thermometry in the near-infrared domain with a good sensitivity S_rmax = 0.5%·K⁻¹ at 293 K, δT = 0.5 K at 303 K, and $\overline{\delta T}$ = 1.6 K. These molecular thermometers were further incorporated into the shell of Prussian Blue@SiO₂ core–shell nanoparticles. Among the resulting hybrids, PB@SiO₂-acac/(1Tb/1Eu) (with a Tb/Eu ratio of 2/8) stood out by enabling ratiometric temperature sensing based on the Eu³⁺⁵D₀ → ⁷F₂ lifetime, with satisfactory parameters (S_rmax = 0.9%·K⁻¹, δT = 0.21 K at 303 K, and $\overline{\delta T}$ = 1.1 K). These results highlight the potential of simple coordination complexes and their nanohybrids for advanced luminescent thermometry applications. Full article

Arctic warming is expected to alter permafrost landscapes and shift tundra ecosystems from greenhouse gas sinks to sources. We quantified plant biomass and necromass, carbon stocks, and microbial activity across five Low-Arctic tundra sites in the Yana–Indigirka Lowland (Chokurdakh, NE Siberia) during the 2024 growing season. Above- and below-ground plant biomass was measured by harvest adjacent to 50 × 50 m permanent plots; total C and N were determined by dry combustion on an elemental analyzer. Total organic carbon (TOC) stocks were calculated by horizon from TOC (%), bulk density, and thickness. Microbial basal respiration (BR), substrate-induced respiration (SIR), microbial biomass C (MBC), and the metabolic quotient (qCO₂) were assessed in litter/organic (O), peat (T), and mineral gley horizons. Mean above-ground biomass was 15.8 ± 1.5 t ha⁻¹; total living biomass averaged 43.1 ± 1.6 t ha⁻¹. Below-ground biomass exceeded above-ground by 1.73×. Carbon in above-ground, below-ground, and necromass pools averaged 7.8, 12.2, and 12.5 t C ha⁻¹, respectively. Surface organic horizons dominated ecosystem C storage: litter–peat stocks ranged from 234 to 449 t C ha⁻¹, whereas 0–30 cm mineral layers held 18–50 t C ha⁻¹; total (surface + 0–30 cm) stocks spanned 258–511 t C ha⁻¹ among sites. Key contributors to biomass and C storage were deciduous shrubs (Salix pulchra, Betula nana), bryophytes (notably Aulacomnium palustre), and the graminoids (Eriophorum vaginatum). BR and MBC were highest in O and T horizons (BR up to 21.9 μg C g⁻¹ h⁻¹; MBC up to 70,628 μg C g⁻¹) and declined sharply in mineral soil; qCO₂ decreased from O to mineral horizons, indicating more efficient C use at depth. These in situ data show that Low-Arctic tundra C stocks are concentrated in surface organic layers while microbial communities remain responsive to warming, implying high sensitivity of carbon turnover to thaw and hydrologic change. The dataset supports model parameterization and remote sensing of shrub–tussock tundra carbon dynamics. Full article

The development of high-performance electrochemical sensors is crucial for ammonia–nitrogen detection. Therefore, in this study, we successfully prepared one ternary PtNiCo nanosheet via the one-step electrodeposition technique. The ratio of H₂PtCl₆·6H₂O, Ni(NO₃)₂·6H₂O and Co(NO₃)₂·6H₂O and electrodeposition time were controlled. Under optimal conditions, Pt₆Ni₂Co₂-2000 demonstrated outstanding electrocatalytic performance, exhibiting a high oxidation peak current of 45.27 mA and excellent long-term stability, retaining 88.09% of its activity after 12 h. Furthermore, the sensing performance of Pt₆Ni₂Co₂-2000 was evaluated, revealing high sensitivity (10.01 μA μM⁻¹), a low detection limit (0.688 µM), strong anti-interference capability, great reusability, great reproducibility, and remarkable long-term stability. Additionally, recovery tests conducted in tap water, lake water, and seawater yielded highly favorable results. This study demonstrated that designing Pt-based alloys can not only enhance the electrochemical performance of Pt but also serve as an effective strategy for improving electrocatalytic ammonia oxidation and ammonia–nitrogen detection. Full article

This work reports a low-cost, microwave-assisted wet chemistry synthesis of zinc antimonate (ZnSb₂O₆) powders with a trirutile structure, yielding highly homogeneous, nanometric particles. X-ray diffraction (XRD) confirmed the formation of the trirutile phase with lattice parameters of a = 4.664 Å and c = 9.263 Å, and an estimated crystallite size of 42 nm. UV–vis spectroscopy revealed a bandgap of 3.35 eV. Scanning electron microscopy (SEM) showed that ethylenediamine, as a chelating agent, formed porous microstructures of microrods and cuboids, ideal for enhanced gas adsorption. Brunauer–Emmett–Teller (BET) analysis revealed a specific surface area of 6 m²/g and a total pore volume of 0.0831 cm³/g, indicating a predominantly mesoporous structure. The gas sensing properties of ZnSb₂O₆ pellets were evaluated in CO and C₃H₈ atmospheres at 100, 200, and 300 °C. The material exhibited high sensitivity at 300 °C, where the maximum responses were 5.86 for CO at 300 ppm and 1.04 for C₃H₈ at 500 ppm. The enhanced sensitivity at elevated temperatures was corroborated by a corresponding decrease in electrical resistivity. Furthermore, the material demonstrated effective photocatalytic activity, achieving up to 60% degradation of methylene blue and 50% of malachite green after 300 min of UV irradiation, with the process following first-order reaction kinetics. These results highlight that ZnSb₂O₆ synthesized by this method is a promising bifunctional material for gas sensing and photocatalytic applications. Full article

H₂S detection is critical for personal and industrial safety. Generally, metal oxide-based H₂S sensors exhibit no response at room temperature (RT). In this study, CuO/ZnWO₄ (C-ZWO) nanocomposites were prepared via a two-step hydrothermal process and applied to RT H₂S sensing. The results show that the C-ZWO sensors exhibit an elevated response value at RT and balanced gas-sensing properties at 100 °C. Significantly, the response value of a 10% C-ZWO sensor to 25 ppm of H₂S at RT is 651.6 with a response time of 78 s, which is 310.3 times that of the ZnWO₄ sensor (2.1). The systemic characterization results suggest that the enhanced RT H₂S-sensing properties are ascribed to the synergistic effects of the growth-specific surface area and oxygen vacancy occupancy, the enhanced oxygen reduction ability, and the formation of the p–n heterojunction structure between CuO and ZnWO₄. The C-ZWO nanocomposites possess added active sites for H₂S adsorption and dissociation, with the p–n heterojunction giving rise to higher electrical resistance, and thus, the follow-up produces a high response value even at RT. Full article

Currently, chalcopyrite is the world’s largest copper reserve. Commonly, the copper contained in chalcopyrite is obtained by pyrometallurgical processes. Still, in recent years, due to the environmental problems generated by this route, more environmentally friendly techniques have been proposed, such as hydrometallurgy; but chalcopyrite has the drawback of passiveness. A promising alternative to minimize this phenomenon is using polar organic solvents in an acidic medium, obtaining copper extraction percentages of 90% in five h. A solvent that has significant functionality is methanol. Moreover, a topic barely studied in depth is the characterization of the gases emitted in the leaching of minerals such as chalcopyrite. In this sense, one gas generated through chalcopyrite leaching is molecular hydrogen, which would increase the economic viability of the process. In this work, the gases formed during the leaching of chalcopyrite concentrate are analyzed, and the formation of only molecular hydrogen by gas chromatography was detected. The hydrogen production was 0.24 µmol in 300 min, and the copper extraction was around 65%, using a concentration of 0.5 M of H₂SO₄, 60 mL of methanol, and 20 mL of H₂O₂. Thus, based on the detected chemicals in solid residues of the leaching of chalcopyrite concentrate, the thermodynamic analysis supports the spontaneous formation of hydrogen with a value of ΔG = −119.66 kJ/mol. Full article

The abuse of quinolone antibiotics in the medical and livestock industries potentially causes environmental accumulation that may impair ecological stability. Based on the organic ligand 5-(pyrazole-1-yl) pyridine-5-yl) terephthalic acid (H₂PPIPA), a terbium(III) complex, [Tb(HPPIPA)(PPIPA)(H₂O)]ₙ (complex 1), was synthesized via solvothermal reaction with Tb(NO₃)₃·6H₂O. Luminescence studies revealed that complex 1 functions as a turn-on fluorescent probe for the selective detection of ofloxacin (OFX), levofloxacin (LFX), and norfloxacin (NFX), with detection limits of 27.9, 17.1, and 8.0 nM, respectively. Owing to its high selectivity and anti-interference capability, the complex was successfully applied for the determination of OFX and LFX in milk samples. Furthermore, a test strip impregnated with complex 1 enabled naked-eye fluorescence detection of OFX, LFX, and NFX under 254 nm UV light. Additionally, a fluorescence sensing film fabricated from complex 1 exhibited excellent recyclability, allowing for at least seven consecutive detection cycles without significant signal loss. This study innovatively designed and synthesized a novel Tb(III)-based coordination polymer fluorescent probe utilizing an original ligand scaffold, achieving the first reported visual detection of quinolone antibiotics with fluorescence test strips and agar films. Full article

Lanthanide hydrogen-bonded organic frameworks (Ln-HOFs) integrating luminescent and proton-conductive properties hold significant promise for multifunctional sensing and energy applications, yet their development remains challenging due to the difficulty of balancing structural stability and functional diversity. In this context, this study successfully synthesized a novel neodymium(III)-based hydrogen-bonded framework material, formulated as {Nd(H₂O)₃(4-CPCA)[H(4-CPCA)]∙H₂O}ₙ (SNUT-15), via hydrothermal assembly using 1-(4-carboxyphenyl)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (H₂(4-CPCA)) as the ligand. Single-crystal X-ray diffraction analysis revealed a rare two-dimensional hydrogen-bonded bilayer structure stabilized by π-π stacking interactions and intermolecular hydrogen bonds. Hirshfeld surface analysis further corroborated the structural characteristics of this material. Moreover, leveraging the superior luminescent properties of lanthanide elements, this crystalline material exhibits dual functionality: selective fluorescence quenching toward Fe³⁺, La³⁺, and Mn²⁺ (with detection limits of 1.74 × 10⁻⁴, 1.88 × 10⁻⁴, and 3.57 × 10⁻⁴ mol·L⁻¹, respectively), as well as excellent proton conductivity reaching 7.92 × 10⁻³ S cm⁻¹ under conditions of 98% relative humidity and 353 K (80 °C). As a multifunctional neodymium(III)-based HOF material, SNUT-15 demonstrates its potential for applications in environmental monitoring and solid-state electrolytes, providing valuable insights into the rational design of lanthanide-containing frameworks. Full article

It is critical to provide proper environmental conditions in poultry houses to maintain birds’ health, boost productivity, and improve the overall economic viability of the poultry industry. Among the myriad of environmental elements, indoor air quality has been a determining factor that directly affects poultry well-being. Elevated concentrations of harmful gases—in particular Carbon Dioxide ($C{O}_2$), Methane ($C{H}_4$), and Ammonia ($N{H}_3$)—decomposition products of poultry litter, feed wastage, and biological processes have draconian effects on bird health, feed efficiency, the growth rate, reproduction efficiency, and mortality rate. Despite their importance, traditional air quality monitoring systems are often operated manually, labor intensive, and cannot detect sudden environmental changes due to the lack of real-time sensing. To overcome these limitations, this paper presents an interdisciplinary approach combining cloud computing, Artificial Intelligence (AI), and Internet of Things (IoT) technologies to measure real-time poultry gas concentrations. Real-time sensor feeds are transmitted to a cloud-based platform, which stores, displays, and processes the data. Furthermore, a machine learning (ML) model was trained using historical sensory data to predict the next-day gas emission levels. A web-based platform has been developed to enable convenient user interaction and display the gas sensory readings on an interactive dashboard. Also, the developed system triggers automatic alerts when gas levels cross safe environmental thresholds. Experimental results of $C{O}_2$ concentrations showed a significant diurnal trend, peaking in the afternoon, followed by the evening, and reaching their lowest levels in the morning. In particular, $C{O}_2$ concentrations peaked at approximately 570 ppm during the afternoon, a value that was significantly elevated (p < 0.001) compared to those recorded in the evening (~560 ppm) and morning (~555 ppm). This finding indicates a distinct diurnal pattern in $C{O}_2$ accumulation, with peak concentrations occurring during the warmer afternoon hours. Full article

As an important reserve resource for cultivated land, the improvement and fertility enhancement of saline-alkali land are key to alleviating the pressure on cultivated land and ensuring the sustainable utilization of land resources. Studying the regulatory effect of rotation patterns on the soil fertility of saline-alkali land is one of the core research contents in exploring low-cost and environmentally friendly comprehensive management strategies for saline-alkali land. This study focuses on Zhaoyuan County, a representative saline and alkaline area within the Songnen Plain. Utilizing remote sensing technology, crop information was systematically collected across 13 time periods spanning from 2008 to 2020. These data were employed to construct a comprehensive crop information change atlas. This atlas categorized crop rotation patterns based on crop combinations, rotation frequencies, and the number of consecutive years of planting. Using soil sampling data from 2008 and 2020, a soil fertility evaluation was conducted, and the changes in soil chemical properties and fertility under various crop rotation patterns were analyzed. The results of the study show that, during the study period, crop rotation patterns in Zhaoyuan County were dominated by paddy-upland rotations and upland crop rotations. Crop rotation patterns, categorized by crop combination, were dominated by soybean–maize–other crops rotation (S-M-O) and rice–soybean–maize–other crops rotation (R-S-M-O). The frequency of crop rotation is dominated by low- and medium-frequency crop rotation. Crop rotation significantly increased soil organic matter, total nitrogen content, and overall soil fertility in the study area, while simultaneously lowering soil pH levels. Crop rotation patterns with different crop combinations had significant effects on soil chemical properties, with smaller differences in the effects of different rotation frequencies and years of continuous cropping. Crop rotation patterns incorporating soybean demonstrate a significant positive regulatory impact on the soil fertility of saline-alkali land. Low-frequency crop rotation (with ≤5 crop changes) has a relatively better effect on improving soil fertility. This research provides important empirical support and decision-making references for establishing sustainable farming systems in ecologically fragile saline-alkali areas, ensuring regional food security, and promoting the long-term sustainable utilization of land resources. Full article