Nanomaterials最新文献

This work investigates the effect of pre-nitriding treatment before vacuum carburizing on the carburizing efficiency of 20CrMnTi steel. The results show that pre-nitrocarburizing significantly enhances the vacuum carburizing efficiency of 20CrMnTi steel, refines the microstructure of the carburized layer's martensite, and promotes the precipitation of carbides. At the same carburized layer depth, the hardness and carbon content of the pre-nitrocarburized samples are significantly higher than those of the samples without pre-nitriding. Specifically, the effective hardening depth and surface hardness increase by approximately 0.15 mm and 75 HV, respectively. These improvements are attributed to the formation of loose and porous nanoscale nitride particles on the surface during the pre-nitrocarburizing process, which significantly increases the surface roughness and porosity. This surface morphology facilitates the adsorption and inward diffusion of carbon atoms during the carburizing process. This study provides some inspiration for pretreatment techniques to improve the efficiency of vacuum carburizing.

This paper presents a comprehensive investigation into the synthesis, morphological characteristics, electrical conductivity, dielectric behavior, and electrocatalytic activity of perovskite-structured iron manganite (FeMnO₃), with a specific focus on its performance in the hydrogen evolution reaction (HER). FeMnO₃(FMO) nanoparticles (NPs) were synthesized using a sol-gel-type Pechini method and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (FESEM-EDS). XRD analysis confirmed the formation of a crystalline structure with cubic symmetry assigned to the Ia-3 space group, with an average crystallite size of 52.47 nm. FESEM images revealed a relatively uniform morphology with an average particle diameter of 55.84 nm. The redox and oxidation states of Fe and Mn can be studied by temperature-programmed oxidation (TPO-O₂) in order to understand oxygen uptake and metal oxidation processes occurring within the FMO lattice. The dielectric constant, dielectric loss, electric modulus and electrical conductivity were calculated as a function of frequency and temperature using a Novocontrol Alpha-A broadband dielectric spectrometer (Novocontrol system) coupled with the LCR-800 precision meter. The dielectric data reveal that the FMO has semiconducting behavior with dominant charge- or ionic-relaxation processes. The electrocatalytic activity toward the HER was evaluated using linear sweep voltammetry (LSV), with the working electrode modified by an FMO catalyst ink. The material exhibited significant catalytic activity within the HER potential range, and an increase in the number of cycles led to stabilized current and enhanced hydrogen evolution. These results highlight the stability of FeMnO₃ for hydrogen generation.

The journal retracts the article titled "Seawater Absorption and Adhesion Properties of Hydrophobic and Superhydrophobic Thermoset Epoxy Nanocomposite Coatings" [...].

Metal hydride-based hydrogen storage reactors combine high volumetric hydrogen density with intrinsic safety, yet their performance is fundamentally limited by inefficient thermal management arising from the strong coupling among heat transfer, thermodynamics, and reaction kinetics. The highly exothermic and endothermic nature of hydrogen absorption and desorption requires rapid and spatially uniform heat removal or supply, which is difficult to achieve due to the low thermal conductivity and complex internal structure of hydride beds. This review presents a mechanistic and architectural overview of thermal management in metal hydride hydrogen storage reactors. Key heat transfer limitations within hydride beds are first analyzed, followed by a systematic classification and critical comparison of major thermal management architectures, including bed-level modifications, structural reactor designs, and heat-exchanger intensification strategies such as embedded tubes, fins, and phase-change materials. The advantages and limitations of these approaches are discussed in terms of heat transfer efficiency, hydrogen storage capacity, structural complexity, and scalability. Finally, the review highlights the central design trade-offs governing compactness, efficiency, and manufacturability, and outlines future directions toward application-oriented and scalable reactor design through integrated thermal and structural optimization.

Colloidal PbSe quantum dots are promising candidates as saturable absorbers for ultrafast fiber lasers, but their performance is often limited by surface-related defects and chemical instability, leading to aggregation under optical pumping. In this study, we present a freestanding PbSe/PbS quantum dot-polystyrene composite saturable absorber film, with PbS overcoating on PbSe to enhance surface passivation and oxidation resistance. The composite exhibits a saturation intensity of 5.76 kW·cm^-2, a modulation depth of 33%, and an optical damage threshold of 13.6 mJ·cm^-2. When integrated into a bidirectionally pumped erbium-doped fiber laser in the anomalous-dispersion regime, the device demonstrates self-starting soliton mode locking at an ultralow pump threshold of 6 mW, generating 1.06 ps pulses with a radio-frequency signal-to-noise ratio of approximately 65 dB. The spectra remain stable over an 8-month period, showing excellent environmental and operational durability. These findings confirm that PbSe/PbS quantum dots in a polymer matrix offer a robust, low-threshold saturable absorber platform for ultrafast fiber lasers.

Linalyl acetate is a key bioactive component of essential oils with notable calming and sedative effects; however, its high volatility severely limits stability and practical application. Herein, bimodal mesoporous silica (BMMs) was employed as an efficient carrier to encapsulate linalyl acetate using liquid- and gas-phase loading strategies, enabling high loading capacity and sustained release. Under optimized gas-phase conditions (600 mg·mL^-1, 85 °C, 2 h), a maximum loading capacity of 80.13% was achieved. The X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) patterns, scanning electron microscopy (SEM) images, N₂ adsorption-desorption isotherms, Fourier transform infrared (FT-IR) spectra, and thermogravimetric (TG) performances confirmed the successful confinement of linalyl acetate within the bimodal mesoporous channels. Particularly, the SAXS patterns revealed the pronounced fractal characteristics, whereas the increased mass-fractal dimension (D_m) values indicated the enhanced structural compactness, and higher surface-fractal dimension (D_s) values reflected increased surface roughness upon loading. Release experiments conducted in an open environment demonstrated an excellent sustained-release performance, with only 22.41% of linalyl acetate released from BMMs over 30 days, compared with 94.41% for the free compound. Molecular dynamics simulations further elucidated that the interactions between linalyl acetate molecules and surface silanol groups dominated the adsorption process and governed diffusion within the mesoporous channels. These findings suggested that BMMs provide a robust platform for stabilizing volatile fragrance compounds and achieving long-term controlled release.

In this work, we synthesized blue-fluorescent nitrogen-doped carbon quantum dots (N-CQDs) via a facile, economical, and environmentally friendly one-pot synthesis, using citric acid as the carbon source and polyethyleneimine (PEI) as the nitrogen dopant. The as-prepared N-CQDs exhibited uniform size distribution, with an average diameter of approximately 3 nm and a quantum yield of up to 23.6%. Based on the mechanism of HClO-triggered static fluorescence quenching and oxidation of surface amine groups on the N-CQDs, we established a quantitative detection platform for hypochlorous acid (HClO). The proposed method demonstrated a linear response over the concentration range of 0-40 μmol/L, with a detection limit as low as 0.17 μmol/L. It also featured a rapid response time (within 2 min), high selectivity, and strong anti-interference capability against various common species, including Cl^-, H₂O₂, NO₂^-, NO₃^-, TBHP, TBO•, Br^-, I^-, S^2-, F^-, O^2- and HO•. Furthermore, the probe was successfully applied to detect HClO in real-world samples such as river water and beer. Owing to its outstanding photostability and low toxicity, it proved highly effective for monitoring intracellular HClO in living cells.

The green synthesis of nanomaterials using biological resources has emerged as a sustainable alternative to conventional chemical routes. In this study, the wild ectomycorrhizal mushroom Russula sanguinea (Rs) was employed as a natural reducing and stabilizing agent for the biosynthesis of silver-decorated zinc-based nanostructures (Ag-ZnNSs/Rs). The formation and physicochemical properties of the nanostructures were systematically characterized using UV-Vis spectroscopy, FT-IR spectroscopy, SEM, TEM, and EDX analysis. Transmission electron microscopy revealed predominantly spherical nanoparticles with good dispersion, and quantitative analysis of 227 individual particles demonstrated an average diameter of 19.36 ± 7.89 nm (range: 10.92-61.00 nm). FT-IR analysis confirmed the involvement of fungal biomolecules in metal ion reduction and surface stabilization, indicating effective bio-capping of the nanostructures. The biofunctional performance of the biosynthesized Ag-ZnNSs/Rs was evaluated through antioxidant and antimicrobial assays. Compared to the crude mushroom extract, the nanostructures exhibited significantly enhanced 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with an IC₅₀ value of 7.29 ± 0.10 mg mL^-1 compared to 13.66 ± 0.15 mg mL^-1 for the crude extract. In addition, notable antimicrobial activity was observed against representative Gram-positive and Gram-negative bacteria (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) as well as the yeast Candida albicans. Overall, this study demonstrates that Russula sanguinea is an effective biological platform for the green synthesis of silver-decorated zinc-based nanostructures with improved biofunctional properties, highlighting the potential of wild mushrooms as underexplored resources in sustainable nanomaterial development.

The polarization of light is recognized as a key physical quantity in describing light-matter interactions. Polarizers are fabricated to selectively respond to light beams with different polarizations. In practice, the operations of a polarization measuring setup require bulky and expensive terminal photodetectors, e.g., a spectrophotometer, to measure the spectral responses associated with different polarizations. To get rid of the unfavorable reliance on conventional photodetectors, polarizers having a Cu-ZnO junction for efficient hot-electron extraction have been designed to give rise to direct electrical readouts. Detailed photoelectric studies reveal that the designed device excites guided-mode resonances with which the device exhibits polarization-dependent energy depositions in absorbable Cu, leading to distinct electrical responses between transverse electric and transverse magnetic polarizations. The electrical extinction ratio increases from 2.7 to 4.4 when the resonance wavelength increases from 767 nm to 869 nm.

Biofilm-associated infections remain a major barrier to wound healing, implant integration, and chronic infection management. Rare-earth oxides (REOs) have emerged as promising antibiofilm materials, though their mechanisms, limitations, and translational potential are still being defined. Cerium oxide (CeO₂) serves as the benchmark due to its redox adaptability, oxygen-vacancy-driven catalytic activity, and host compatibility. In contrast, non-ceria REOs show antibiofilm effects under more restricted conditions, often requiring surface functionalization, composite architectures, or hybrid organic-inorganic interfaces-such as polyphenol coatings or hydroxyapatite-based composites-to achieve comparable activity. Across systems, biofilm control arises not from bactericidal potency but from matrix-level mechanisms including extracellular polymeric substance (EPS) destabilization, extracellular DNA (eDNA) sequestration, redox modulation, and quorum-sensing interference. Preclinical and near-clinical evidence, particularly in chronic wound models, supports the translational relevance of these mechanisms, though the evidence base remains preliminary. This review synthesizes mechanistic data across cerium-, samarium-, lanthanum-, and strontium-based systems to establish a unified framework for REO-mediated biofilm disruption. REOs are positioned as biofilm-modulating platforms that complement antibiotics, enhance healing, and improve outcomes. Design rules emphasize controlled redox activity, targeted coordination chemistry, functional surface engineering, and host-compatible performance, alongside regulatory and manufacturing guidance for future development.