Search Results (173)

Pt-based intermetallics are high-efficiency electrocatalysts for the hydrogen evolution reaction (HER) in proton exchange membrane water electrolysis (PEMWE). However, the synthesis of intermetallics usually relies on high-temperature annealing, which easily induces particle agglomeration and limits the improvement of catalytic performance. In this study, a synergistic strategy of spatial confinement and ordered structure regulation is adopted, and indene-derived mesoporous carbon (IMC) is used as the support to controllably synthesize the intermetallic Pt₃Fe catalyst. The IMC support can anchor and spatially confine nanoparticles, thereby preventing particle sintering and agglomeration during high-temperature annealing. In 0.5 mol·L⁻¹ H₂SO₄ electrolytes, the catalyst exhibits excellent catalytic performance: it achieves an overpotential of only 19.1 mV at a current density of 10 mA·cm⁻², which is 9.4 mV lower than that of commercial Pt/C; its mass activity reaches 2.76 A·mg_Pt⁻¹, 8 times that of commercial Pt/C. Chronopotentiometry measurements show negligible potential variation after 190 h of operation at 10 mA·cm⁻². This strategy suppresses particle agglomeration through the spatial confinement effect of IMC and modulates electronic states via the ordered structure, providing a practical route for the scalable preparation of low-cost, highly active and high-stability Pt-based intermetallics for PEMWE applications. Full article

Significant differences in hydrogen adsorption on amorphous and crystalline gold nanoparticles deposited on highly oriented pyrolytic graphite (HOPG) were revealed. Crystalline nanoparticles were synthesized via the impregnation–precipitation method followed by annealing at 700 K, whereas amorphous ones were obtained using the laser electrodispersion method. The morphology and electronic structure of single nanoparticles were investigated with high spatial resolution using scanning tunneling microscopy and spectroscopy (STM/STS) in ultra-high vacuum both before and after exposure to molecular hydrogen at doses of 400–6000 L. Experiments performed at room temperature showed that the surface coverage by the adsorbate in both cases begins at the Au-HOPG interface, spreads towards the center of the particle, and corresponds to the island growth model. However, amorphous nanoparticles have fewer growth sites at the periphery compared to crystalline ones. The local electronic structure of amorphous nanoparticles is more inhomogeneous compared to crystalline ones, demonstrating variation across different points on the nanoparticle surface. It was shown that dissociative chemisorption of hydrogen takes place on amorphous gold nanoparticles with a size of 4–6 nm. Chemisorption is completely inhibited when the nanoparticle size is reduced to 2 nm or less. Full article

CuO thin layers were synthesized using the sol–gel method and deposited onto glass substrates through the dip-coating technique. The impact of annealing temperatures on the structural, optical, and electrical characteristics of the developed CuO thin layers was comprehensively assessed through X-ray diffraction, UV–visible spectrophotometry, and four-point techniques, respectively. X-ray diffraction analysis revealed the formation of CuO thin layers with a distinctive monoclinic tenorite phase structure. The UV–visible spectrophotometer results demonstrated a decrease in transmittance from approximately 30% to about 7% as the annealing temperature increased from 200 °C to 400 °C. The semiconducting properties exhibited temperature-dependent variations, with the band gap narrowing from 1.70 to 1.48 eV as the temperature increased from 200 to 400 °C. Additionally, the electrical conductivity of the CuO layers exhibited a significant increase from 48 to 61 S.m⁻¹ over the same temperature range. Collectively, the findings suggest that an annealing temperature of 400 °C is optimal for achieving well-crystallized CuO layers with desirable characteristics, including high absorbance, low transmittance, a reduced energy band gap, and enhanced electrical conductivity. These results underscore our ability to manipulate CuO properties, offering insights for tailoring them to meet specific requirements, particularly in the context of gas sensor applications. Full article

Thin-film cobalt oxides have attracted increasing attention due to their visible-light activity and potential environmental applications. In this work, Co₃O₄ coatings were prepared on glass substrates through a sol–gel dip-coating process followed by thermal treatment at 450, 500, and 550 °C. Structural characterization was carried out using X-ray diffraction (XRD) and Raman spectroscopy. Diffraction patterns, together with the Raman spectra, indicate the formation of the cubic spinel phase of Co₃O₄, while sharper diffraction peaks appeared at higher annealing temperatures, indicating improved crystallinity of the films. Surface morphology was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM observations revealed continuous polycrystalline coatings, whereas AFM measurements showed clear variations in surface topography and roughness produced by thermal treatment. Wettability measurements obtained from contact angle (CA) analysis indicate modifications in the surface properties of the films as the annealing temperature changes. Optical characterization performed by ultraviolet–visible spectroscopy (UV–Vis) showed strong absorption in the visible region with an indirect band gap close to 1.58 eV. Photocatalytic activity was evaluated through the degradation of methylene blue under visible-light irradiation. Degradation efficiencies of approximately 93.9%, 97.4% and 98.7% were obtained after 5 h for films annealed at 450, 500, and 550 °C, respectively. Full article

This study systematically investigates the formulation–property relationships of epoxy-based silver conductive adhesives by varying silver filler architecture, total filler loading, and organic carrier design. Rotational viscometry, four-point probe measurements, thermal conductivity analysis, and scanning electron microscopy (SEM) were employed to elucidate the correlations among rheological behavior, conductive network formation, and electrical–thermal transport properties. All formulations incorporate dicyandiamide (DICY) as a latent curing agent, in combination with a thermally activated accelerator and silane coupling agents, to stabilize filler–matrix interfaces and suppress moisture-assisted side reactions. This latent curing chemistry enables effective low temperature curing at approximately 155 °C, providing compatibility with temperature-sensitive flexible polymer substrates. After sealed storage at 25 °C and 60% relative humidity for two weeks, all formulations exhibited viscosity variations within ≤16%, demonstrating extended pot life and good storage stability under ambient conditions. Meanwhile, the normalized volume resistivity and thermal conductivity remained close to their initial values, with maximum relative deviations of approximately 12% and 7%, respectively, from the initial (Day 0) values across all formulations, indicating stable electrical and thermal transport properties during storage. Differences in conductive network formation and filler packing characteristics were reflected in the observed electrical and thermal transport behaviors. Balanced electrical–thermal performance was achieved without the need for high-temperature sintering or post-annealing, underscoring the effectiveness of the low temperature curing strategy. Overall, this work defines a practical formulation design window that simultaneously achieves low temperature curability, long pot life, stable rheology, and robust electrical–thermal performance. The results provide useful material-level guidelines for the development of epoxy-based silver conductive adhesives intended for conductive interconnects on flexible polymer substrates and related flexible electronic applications. Full article

To enable the efficient and environmentally benign treatment of phenol-containing wastewater, a nitrogen-doped porous carbon material (denoted as 900-CN) was synthesized via high-temperature annealing of a composite composed of humic acid (HA) and g-C₃N₄. The as-prepared materials were characterized, and their catalytic performance in activating peroxymonosulfate (PMS) for phenol degradation was investigated. The results demonstrate that g-C₃N₄ acts as a layered template; upon high-temperature annealing, it gradually evolves into a highly wrinkled and porous architecture. This morphology substantially increases the specific surface area, thereby facilitating pollutant removal. PMS formed metastable surface complexes on 900-CN, enabling concomitant electron transfer. Concurrently, functional groups on the HA-derived carbon reacted with PMS to generate singlet oxygen (¹O₂), a highly oxidative species that markedly enhanced phenol degradation. The 900-CN composite achieved complete phenol removal (100%) within 60 min. Variations in reaction temperature (20–50 °C) and initial pH (2–10) exhibited negligible influence on the performance of the 900-CN/PMS system. Reactive species in the 900-CN/PMS/phenol system included •OH, SO₄^•−, O₂^•−, and ¹O₂, indicating that phenol degradation occurred through combined radical and non-radical pathways. These findings highlight the strong potential of 900-CN as a promising catalyst for the treatment of phenolic wastewater. Full article

Feline infectious peritonitis (FIP) is a highly lethal disease caused by feline infectious peritonitis virus (FIPV), which poses significant diagnostic challenges in clinical practice. FIPV is divided into two serotypes (serotype I and serotype II) based on distinct serological responses driven by substantial sequence divergence in the spike (S) protein. Serotype I predominates in Europe and North America, whereas serotype II is more common in Asia. In this study, we developed a triplex reverse transcription quantitative PCR (RT-qPCR) assay for simultaneous detection and serotyping of FIPV. Primers and TaqMan probes were designed to target the conserved nucleocapsid (N) gene and serotype-specific regions within the S gene. After systematic optimization of reaction conditions, the final assay employed an annealing temperature of 64 °C and optimized primer–probe concentrations. The assay exhibited excellent linearity (R² > 0.99 for all targets), with amplification efficiencies ranging from 97.39% to 109.97%. No cross-reactivity was observed with other common feline pathogens, confirming high specificity. The limit of detection was as low as 0.5 copies/µL, and intra-assay repeatability showed coefficients of variation below 2.1%. Clinical validation using 63 feline samples revealed an overall FIPV positivity rate of 21.63%, with serotype II (17.46%) markedly more prevalent than serotype I (3.17%). Collectively, this triplex RT-qPCR assay demonstrates high sensitivity, exceptional specificity, and robust reproducibility, making it a valuable tool for rapid clinical diagnosis through the simultaneous detection of feline coronavirus (FCoV) and serotyping of FIPV. Full article

Hydrogen is a key energy carrier for fuel cell vehicles and hydrogen energy systems. However, its colorless and odorless nature, combined with a wide flammability range, poses significant safety risks in the event of leakage. Accordingly, compact and reliable hydrogen sensors capable of low-ppm detection at moderate operating temperatures are essential for early-stage safety monitoring. In this study, a bias-optimized hydrogen gas sensor based on a Pd-functionalized SnO₂ thin film with Mo electrodes and an integrated microheater is designed, fabricated, and systematically characterized. The sensor employs a Mo-based vertical microheater and a multilayer thermal insulation stack, enabling thermally efficient and stable operation at 250–280 °C with low power consumption. The electrical and sensing properties of the SnO₂ layer are optimized by controlling the oxygen partial pressure during reactive sputtering and post-deposition annealing. The Pd catalytic layer promotes hydrogen dissociation and spillover, resulting in pronounced resistance modulation through surface redox reactions and interfacial charge transport effects. By systematically optimizing the sensing bias voltage, a clear trade-off between sensitivity enhancement and electrical noise is identified, which allows stable and repeatable operation in the low-ppm regime. The sensor response follows a power-law dependence on hydrogen concentration, and an automated measurement platform is employed to evaluate repeatability and statistical performance. Based on baseline noise analysis and concentration-dependent resistance variation, a limit of detection of approximately 6.4 ppm is achieved. Furthermore, a concentration-normalized figure of merit that combines response magnitude and concentration dependence is introduced to quantitatively assess low-concentration hydrogen sensing performance. These results demonstrate that the proposed Mo-electrode Pd/SnO₂ thin-film sensor, enabled by bias-optimized operation and integrated thermal control, provides a robust and scalable platform for safety-critical hydrogen leak detection. Full article

This paper explores the potential of amorphous and nanocrystalline glass-coated microwires as highly versatile, miniaturized sensing elements, leveraging their intrinsic nonlinear magnetization dynamics. In magnetic systems, this approach is particularly advantageous because the degree of nonlinearity can be externally tuned using stimuli such as applied magnetic fields, mechanical stress, or temperature variations. From this context, we summarize key properties of microwires—including bistability, a specific easy magnetization direction, internal stress distributions, and magnetostriction—that can be tailored through composition and annealing. In this review, we compare for the first time two key contactless readout methodologies: (i) time-domain detection of the switching field and (ii) frequency-domain harmonic analysis of the induced voltage. These principles have been successfully applied to a broad range of practical sensors, including devices for monitoring mechanical stress in structural materials, measuring temperature in biomedical settings, and detecting magnetic particles. Together, these advances highlight the potential of microwires for embedded, wireless sensing in both engineering and medical applications. Full article

In this study, a multi-gradient microstructure was introduced into medium-Mn steel through torsion following heat treatment at different annealing temperatures, and through investigations on the mechanical properties under two annealing temperatures, it has also been revealed that different annealing temperatures before torsion affect the stability of austenite after torsion, thereby leading to distinct variations in mechanical performance. The yield strengths of the studied steel after annealing at 600 °C and 620 °C were 762 MPa and 673 MPa, with total elongation of 47.4% and 44.1%, respectively. After 90° torsion, the yield strength of experimental steels increased to 834 MPa and 808 MPa, while the elongation decreased to 21.6% and 29.5%, respectively. The gradient distributions from the center to the edge were observed for the austenite volume fraction, average grain size, martensite volume fraction, GND density, and hardness. The comparative analysis of the two annealing temperatures indicates that the larger grain size in the 620—annealed sample leads to its lower yield strength, while its higher austenite volume fraction and moderate stability promote a more sustained TRIP effect during deformation, contributing to its enhanced elongation. This multi-gradient microstructure is responsible for the yield strength improvements of 72 MPa and 135 MPa in the torsioned samples annealed at 600 °C and 620 °C, respectively. Full article

Chicken respiratory diseases represent multifactorial conditions resulting from viral, bacterial, mycoplasmal pathogens, and environmental factors, causing significant economic losses within the poultry industry. A specific respiratory disease characterized by breathing difficulties and bronchial occlusion due to caseous exudates is termed chicken bronchial obstruction. However, the absence of rapid, precise, and highly sensitive diagnostic methods for differentiation of primary respiratory disease pathogens or opportunistic pathogens, including avian influenza virus (AIV), infectious bronchitis virus (IBV), Pseudomonas aeruginosa (P. aeruginosa), and Escherichia coli (E. coli), constitutes a substantial challenge. This study developed a quadruplex droplet digital polymerase chain reaction (ddPCR) method that targeted the HA gene of H9 subtype AIV, the M gene of IBV, the Pal gene of P. aeruginosa, and the UidA gene of E. coli. Following the optimization of annealing temperature, sensitivity, and repeatability, the minimum detectable concentrations were determined as 3.02 copies/μL for the HA gene of H9 subtype AIV, 3.08 copies/μL for the M gene of IBV, 3.19 copies/μL for the Pal gene of P. aeruginosa, 3.39 copies/μL for the UidA gene of E. coli. No cross-reactivity was observed with Newcastle disease virus (NDV), H5 subtype AIV, H7 subtype AIV, fowl adenovirus serotype 4 (FAdV-4), infectious laryngotracheitis virus (ILTV), Avibacterium paragallinarum, Streptococcus, Salmonella, Pasteurella multocida, and Staphylococcus aureus. The method demonstrated excellent repeatability, with a coefficient of variation (CV) below 9%. The 185 clinical samples collected in Hebei Province China are tested by both quadruplex ddPCR and quadruplex qPCR method and the results compared. The sensitivity of the quadruplex ddPCR method (57.30%; 106/185) slightly exceeded that of the quadruplex qPCR method (49.73%; 92/185). Pathogens or opportunistic pathogens positive rates obtained via the quadruplex ddPCR were 40.00% for H9 subtype AIV, 33.51% for IBV, 24.32% for P. aeruginosa, and 27.57% for E. coli. In comparison, the positive rates of H9 subtypes AIV, IBV, P. aeruginosa, and E. coli from the quadruplex qPCR were 36.22%, 30.81%, 21.62%, and 24.32%, respectively. The coincidence rates between the two methods were 96.22% for H9 AIV, 97.30% for IBV, 97.30% for P. aeruginosa, and 96.76% for E. coli. These results demonstrated that the quadruplex ddPCR method represented a highly sensitive, specific, and rapid technique for identifying H9 subtype AIV, IBV, P. aeruginosa, and E. coli. Full article

Cerium (Ce³⁺)-doped gadolinium orthoborate (GdBO₃) phosphor powders were synthesized via an aqueous sol–gel route, with systematic variation in solution pH (2, 5, and 8) and annealing temperature (600–1200 °C, in 100 °C increments) to investigate their influence on structural, optical, and scintillation properties. The materials were comprehensively characterized using thermogravimetric and differential thermal analysis (TG–DTA) to assess thermal behavior, X-ray diffraction (XRD) for crystal structure determination, Fourier-transform infrared spectroscopy (FTIR) for vibrational analysis, and both photoluminescence (PL) and radioluminescence (RL) spectroscopies to evaluate optical and scintillation performance. All samples crystallized in the hexagonal GdBO₃ vaterite phase (space group P6₃/mcm). The PL and RL emission spectra were consistent with the Ce³⁺ 5d–4f transitions, and scintillation yields under X-ray excitation were quantified relative to a standard Gadox phosphor. A decrease in photoluminescence quantum yield (PLQY) was observed at annealing temperatures above 800 °C, which is attributed to the incorporation of Ce³⁺ into the host lattice. Scintillation decay profiles were recorded, enabling extraction of timing kinetics parameters. Overall, the results reveal clear correlations between synthesis conditions, structural evolution, and luminescence behavior, providing a rational basis for the optimization of Ce³⁺-doped GdBO₃ phosphors for scintillation applications. Full article

The objective of this study is to evaluate the impact of thermal and thermochemical treatment, specifically gas nitriding, on the wear properties of AISI D2 cold work tool steel. The steel was austenitized at 1050 °C, then subjected to two annealing cycles at 560 °C for two hours each. It was then gas-nitrided for 16 and 36 h. The Vickers microhardness measurements of AISI D2 steel for the three distinct conditions, non-nitrided (NN), nitride at 16 h (N16) and nitride at 36 h (N36), are 560 HV0.1, 1050 HV0.1 and 1350 HV0.1, respectively. Wear tests were conducted utilizing a ball device, under dry friction conditions at ambient temperature, with loads of 5, 10 and 15 N, over 5000, 10,000 and 15,000 cycles at a constant sliding velocity of 30 mm/s and a sliding distance of 10 mm. Furthermore, the utilization of ANFIS modeling of experimental data facilitated the prediction of the variation in the coefficient of friction as a function of nitriding conditions and specific test parameters. The results show a significant effect of nitriding, leading to a marked reduction in the coefficient of friction. In the non-nitrided condition, the average value reaches 0.80, while extended nitriding to 36 h reduces this value to around 0.49, confirming a substantial tribological improvement. This enhancement is ascribed to the formation of hard, resilient nitride layers on the steel surface, thereby increasing wear resistance and cur-tailing in industrial applications. Full article

Amorphous hydrogenated germanium–carbon alloys (Ge_1−xC_x:H) were synthesized by X-ray-activated Chemical Vapor Deposition and investigated to evaluate the effects of annealing on their structure, composition, and properties given the limited information available on their behavior at high temperatures. Thermogravimetric and elemental analyses showed that the materials are stable up to 573 K; above this temperature, the carbon and hydrogen content progressively decrease, favoring structural reorganization. XRPD and Raman analyses demonstrate that the as-deposited films are fully amorphous, while annealing promotes the progressive formation of crystalline Ge. This crystallization occurs heterogeneously through the nucleation of small “islands” embedded within the sample matrix. Optical measurements reveal a narrowing of the band gap with increasing annealing temperature and time. The weak contribution of sp²-carbon observed in some Raman spectra indicates that band gap reduction is mainly governed by the overall composition and the variation of germanium hydrogen bonding configuration, rather than by graphitization. The study also notes that the parameter B^1/2 does not follow a regular trend due to the complex nature of the material’s microstructural evolution during annealing. These results provide a comprehensive picture of the annealing-driven transformations in Ge–C:H alloys relevant for the design of thermally stable optoelectronic materials. Full article

Beta-gallium oxide (β-Ga₂O₃) is a semiconductor with an ultra-wide bandgap, high optical transparency, and excellent electrical properties, which can be finely tuned for a wide range of electronic devices. This study optimized the process conditions for fabricating β-Ga₂O₃ thin films with desired electrical characteristics. β-Ga₂O₃ films were deposited on (100) Si substrates via RF magnetron sputtering with varying O₂ flow rates and post-annealed at temperatures ranging from 600 °C to 800 °C. The structural and electrical properties of the films were analyzed using X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), and Hall effect measurements. The XRD results confirmed the formation of nanocrystalline β-Ga₂O₃, with variations in peak intensities and shifts observed based on O₂ flow rates. The films exhibited carrier concentrations exceeding 5 × 10²² cm⁻³, mobilities ranging from 50 to 115 cm²/Vs, and resistivity around 1 × 10⁻⁶ Ω⋅cm. This study demonstrates that the electrical properties of β-Ga₂O₃ thin films can be modulated during the deposition and post-annealing processes. The ability to control these properties underscores the potential of β-Ga₂O₃ for advanced applications in high-performance high-power devices and optoelectronic devices such as deep ultraviolet photodetectors. Full article