Search Results (731)

A simple and inexpensive thermal oxidation process is used to grow β-Ga₂O₃ oxide (β-Ga₂O₃) thin films/nanorods on a c-plane (0001) sapphire substrate using Ag/Au catalysts. The effect of these catalysts on the growth mechanism of Ga₂O₃ was studied by different characterization techniques, including X-ray diffraction analysis (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray analysis (EDX). The XRD results of the grown Ga₂O₃ on a sapphire substrate show three sharp diffraction peaks located at 19.31°, 38.70° and 59.38° corresponding to the $\left(\overline{2}01\right), \left(\overline{4}02\right)$ and $\left(\overline{6}03\right)$ planes of β-Ga₂O₃. Field Emission Scanning Electron Microscope (FESEM) analysis showed the formation of longer and denser Ga₂O₃ nanowires at higher temperatures, especially in the presence of silver nanoparticles as catalysts. Full article

Aluminum nitride (AlN) thin films were deposited on SiO₂ substrates by RF-magnetron sputtering at varying powers (110–140 W) and subsequently subjected to thermal annealing at 450 °C under nitrogen atmosphere. A comprehensive multi-technique investigation—including X-ray reflectometry (XRR), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), optical profilometry, spectroscopic ellipsometry (SE), and electrical measurements—was performed to explore the physical structure, morphology, and optical and electrical properties of the films. The analysis of the film structure by XRR revealed that increasing sputtering power resulted in thicker, denser AlN layers, while thermal treatment promoted densification by reducing density gradients but also induced surface roughening and the formation of island-like morphologies. Optical studies confirmed excellent transparency (>80% transmittance in the near-infrared region) and demonstrated the tunability of the refractive index with sputtering power, critical for optoelectronic applications. The electrical characterization of Au/AlN/Al sandwich structures revealed a transition from Ohmic to trap-controlled space charge limited current (SCLC) behavior under forward bias—a transport mechanism frequently present in a material with very low mobility, such as AlN—while Schottky conduction dominated under reverse bias. The systematic correlation between deposition parameters, thermal treatment, and the resulting physical properties offers valuable pathways to engineer AlN thin films for next-generation optoelectronic and high-frequency device applications. Full article

The two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is a major pest of horticultural, ornamental, fruit, and strawberry crops worldwide. Currently, various management tools have been explored for this pest, with nanoparticles being one of them, which stand out for their characteristics and multiple effects. This study evaluated the effects of green-synthesized gold nanoparticles (AuNPs) on the mortality and repellency of T. urticae and its natural predator Phytoseiulus persimilis under laboratory conditions, as well as their efficacy in greenhouse tomatoes against T. urticae. In the laboratory, a biological window for AuNPs (50–100 mg L⁻¹) on the pest and predator was established using a residual film method and a free-choice assay. In the greenhouse, four concentrations (300, 500, 750, and 1000 mg L⁻¹) were evaluated via foliar application at 10-day intervals. The results showed susceptibility to AuNPs in all stages of T. urticae and the adult P. persimilis. The death times from AuNPs were similar in both species. Furthermore, the AuNPs were selective for the pest rather than the natural enemy. In greenhouses, AuNPs affected T. urticae populations in tomato plants, and significant differences were observed on some continuous and final agronomic variables (associated with fruits). This study showed that T. urticae and P. persimilis were susceptible to green-synthesized AuNPs. AuNPs can be a management tool, although studies on other non-target species and estimating agronomic effects on other crops are recommended. Full article

Titanium dioxide (TiO₂) is a benchmark photocatalyst for environmental applications, but its limited visible-light activity due to a wide band gap and fast charge recombination restricts its practical efficiency. This study presents the development of heterostructured Ag (Au)/MoS₂-TiO₂ inverse opal (IO) films that synergistically integrate photonic, plasmonic, and semiconducting functionalities to overcome these limitations. The materials were synthesized via a one-step evaporation-induced co-assembly approach, embedding MoS₂ nanosheets and plasmonic nanoparticles (Ag or Au) within a nanocrystalline TiO₂ photonic framework. The inverse opal architecture enhances light harvesting through slow-photon effects, while MoS₂ and plasmonic nanoparticles improve visible-light absorption and charge separation. By tuning the template sphere size, the photonic band gap was aligned with the TiO₂-MoS₂ absorption edge and the localized surface plasmon resonance of Ag, enabling optimal spectral overlap. The corresponding Ag/MoS₂-TiO₂ photonic films exhibited superior photocatalytic and photoelectrocatalytic degradation of tetracycline under visible light. Ultraviolet photoelectron spectroscopy and Mott–Schottky analysis confirmed favorable band alignment and Fermi level shifts that facilitate interfacial charge transfer. These results highlight the potential of integrated photonic–plasmonic-semiconductor architectures for efficient solar-driven water treatment. Full article

The poor interfacial adhesion between ductile gold (Au) electrodes and polydimethylsiloxane (PDMS) substrates affects their application in flexible sensors. Here, a porous Au electrode is designed and combined with a flexible PDMS substrate to form a structure that embeds Au into the PDMS film, thereby enhancing the interfacial adhesion of the Au/PDMS electrode. The resistivity change of the Au/PDMS electrode is only 12.3% after 100 tape peeling trials. The resistance of the Au/PDMS electrode remains stable at the 30% strain level after 2000 tensile cycling tests. This feature is mainly attributed to the deformation buffering effect of the porous Au film. After 100 min of ultrasonic oscillation testing, the resistivity change of the Au/PDMS electrode remains stable. It is also shown that the Au/PDMS electrode has excellent interfacial adhesion properties, which is mainly attributed to the interlocking effect of the Au/PDMS electrode structure. In addition, the temperature coefficient of resistance (TCR) of the temperature sensor based on the Au/PDMS electrode is approximately 0.00320/°C and the sensor’s sensitivity remains almost stable after 200 temperature measurement cycles. Au/PDMS electrodes have great potential for a wide range of applications in flexible electronics due to their excellent interfacial adhesion and electrical stability. Full article

Electrochromic supercapacitors (ECSCs), which visually indicate their operating status through color changes, have attracted considerable attention in the field of wearable electronics. The conductive polymer polyaniline (PANI) shows great potential for integrated intelligent devices by combining bi-functional electrochromic spectral modulation and energy storage capabilities. In this work, a microsphere-like structured PANI-based composite film was fabricated on a porous Au/nylon 66 electrode via a one-step electrochemical copolymerization process, using 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSA) as both the dopant and cross-linking agent for the PANI backbone, serving as the ECSC electrode. Compared to the pristine PANI electrode, the PANI-PTSA composite film exhibits lower intrinsic resistance and higher electrical conductivity, delivering a higher specific capacitance of 310.0 F g⁻¹@1 A g⁻¹ and an areal capacitance of 340.0 mF cm⁻²@1 mA cm⁻², respectively. The dopant facilitates enhanced electrochemical performance by promoting charge transport within the PANI polymer network. Meanwhile, as a counter anion to the PANI backbone, PTSA regulates the growth of PANI chains and acts as a morphological controller. Furthermore, a symmetric ECSC based on the PANI-PTSA_8:1 electrode was assembled, and its electrochemical properties were thoroughly investigated. The device demonstrated a high specific capacitance of 169.2 mF cm⁻² at 1 mA cm⁻², a notable energy density of 23.5 μWh cm⁻² at a power density of 0.5 mW cm⁻², and excellent cycling stability with 79% capacitance retention after 3000 cycles at a current density of 5 mA cm⁻², alongside remarkable mechanical flexibility. Additionally, the working status of the ECSCs can be directly monitored through reversible color changes from yellow-green to deep blue during charge–discharge processes. Full article

The recent focus on wide-bandgap absorbers for tandem solar cell configurations and photovoltaic materials with high absorption coefficients for indoor photovoltaics has prompted a renewed interest in selenium. Over the past few years, the efficiency of Se solar cells has improved significantly, bringing the prospect of industrial production closer to reality. This study presents an innovative vapor transport deposition (VTD) technique for the scalable and cost-effective fabrication of Se thin films. The prepared Se thin films were characterized, and the results show that the VTD method is capable of producing dense and well-crystallized Se thin films. Se solar cells with a structure of glass/FTO/TiO₂/Se/Au were fabricated to evaluate the impact of substrate temperature on device performance. The optimal performance was achieved on the hot side of the substrate during deposition, with a power conversion efficiency (PCE) of 2.56%. This study provides a promising pathway for the low-cost, high-throughput manufacturing of high-performance Se solar cells, facilitating their potential industrial implementation. Full article

As a core structure within the Qing Changling Mausoleum, a UNESCO World Cultural Heritage site, Long’en Hall preserves a relatively complete set of Qing dynasty imperial lacquered furniture. These furnishings provide critical physical evidence for studying Qing dynasty sacrificial rituals and the craftsmanship of court lacquerware. However, limited research has been conducted on the surface finishing techniques of such furnishings, posing challenges to their conservation and accurate restoration. This study focuses on representative furnishings from Long’en Hall—including an offering table, an incense pavilion, a throne, and a poke lamp—and employed a multi-method analytical approach comprising fluorescence microscopy (FM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared (FTIR) spectroscopy. The analysis was conducted on the following two levels: the lacquer layer structure and material composition. The results show that the furnishings in the Long’en Hall adopt the typical structure of “lacquer ash layer–color lacquer layer”, and the color lacquer layer is composed of raw lacquer, tung oil, animal glue, and other natural organic ingredients as film-forming materials, supplemented with inorganic mineral pigments such as red lead (Pb₃O₄) and Au metal, which constitutes a stable organic–inorganic composite structure with the lacquer ash layer. The multi-analysis results show a good complementary and cross-corroboration relationship, providing the necessary technical support and a theoretical reference for Qing dynasty palace lacquer wood furniture as cultural relics worthy of scientific protection and imitation. Full article

(1) Background: Asomate, as a dithiocarbamate compound, is moderately toxic to the human body; thus, it is necessary to develop a rapid and efficient method for detection. To meet this need, this study introduced a rapid, non-destructive, and efficient method for detecting asomate residues on the surface of apples based on surface-enhanced Raman spectroscopy (SERS) combined with flexible substrates. (2) Methods: Concave Au nanorods (AuCNAs) were synthesized in advance. Then, the AuCNAs were loaded on an electrostatically spun film to generate a flexible TiO₂/ZrO₂/AuCNAs substrate for detection. (3) Results: The flexible substrate exhibited strong SERS activity, with an enhancement factor (EF) up to 9.40 × 10⁷ for 4-MBA. Meanwhile, the finite-difference time-domain (FDTD) simulation showed that the localized surface plasmon resonance (LSPR) effects related to the enhancement of the SERS signal are mainly generated from the ‘hot spots’ in AuCNAs. The density functional theory (DFT) simulation detailedly revealed that the SERS peaks could be generated by the interaction among asomate molecules, disassociated Au atoms, and Au facets. Moreover, the asomate in apple peel was analyzed with the limit of detection (LOD) as low as below 10 nM, allowing for the rapid detection of asomate directly on apple peels. (4) Conclusions: The flexible TiO₂/ZrO₂/AuCNAs film can be used for the in situ detection of asomate in apple peel at low concentrations. Moreover, the simulation methods, including FDTD and DFT, explained the mechanism of SERS from the flexible substrates. Full article

This study proposes the development of a dual-wavelength optical fiber sensor (DWOFS) that integrates two optical fiber structures in a multimode transmission line to measure the refractive index and temperature of a liquid concurrently. One structure is based on a refractive index sensor that utilizes surface plasmon resonance, comprising a 5 mm long single-mode fiber (SMF) section coated with chromium/gold (Cr/Au) films. The secondary structure employs a multimode interferometer with a 29 mm long no-core fiber (NCF) section covered with a thick layer of polydimethylsiloxane (PDMS) to measure temperature. The measurements obtained reveal two distinct drops in the transmission spectrum at approximately 600 nm and 1550 nm, respectively, enabling precise measurement of the two parameters. The sensor demonstrates a high degree of sensitivity to both refractive index and temperature, spanning the visible ($2770.30\mathrm{n}\mathrm{m}/\mathrm{R}\mathrm{I}\mathrm{U}$) and infrared $(-0.178\mathrm{n}\mathrm{m}/°\mathrm{C}$) regions of the spectra, respectively. Furthermore, the thermo-optical coefficient for water $({-0.9928\times 10}^{-4}\mathrm{R}\mathrm{I}\mathrm{U}/°\mathrm{C})$ was estimated. The proposed sensor offers a compact solution for the simultaneous measurement of refractive index and temperature in liquid samples for a variety of applications, including biological, environmental, and healthcare research. Full article

S-shaped dinaphtho[2,1-b:2′,1′-f]thieno[3,2-b]thiophene (S-DNTT) molecules have shown promise for applications in organic electronic devices, though their molecular characteristics are not fully understood yet. In this study, we first revealed the material characteristics of S-DNTT-10 by vibrational dynamics using Raman spectroscopy and density functional theory (DFT) simulations, employing the B3LYP functional method and the 6-311G (d, p) basis set. The molecular vibrations identified included C–H bending in alkyl chains and the deformation of S-shaped thiophene rings. In addition, surface-enhanced Raman scattering (SERS) with 785 nm incident light was applied to thermally deposited 25 nm S-DNTT-10 thin films with gold (Au) nanostructures. It showed enhanced Raman signals from the lower S-DNTT-10 layers. The findings significantly contribute to the knowledge of S-DNTT-10 molecular properties and also contribute insights into using this material into organic electronic devices in the future. Full article

A method to prepare free-standing, few-micron-thick films from a dental photopolymer resin, namely UDMA-TEGDMA in a 3:1 weight ratio, doped with gold nanorods, is presented. The method is based on a sandwich structure consisting of a 4 μm thick PVA sacrificial layer, the Au-nanorod/UDMA-TEGDMA nanocomposite layer, and glycerol, all spin-coated sequentially onto a glass slide. Glycerol serves as a cover layer to shut out oxygen during photopolymerization, while the water-soluble PVA enables the subsequent detachment of the nanocomposite film by simple immersion into a liquid bath. Layer thicknesses were controlled by profilometry, while the presence of homogeneously dispersed gold nanorods was confirmed by optical spectroscopy and dark-field optical microscopy. A total of five similar spin-coating scenarios were tested, out of which two approaches produced positive results, with final nanocomposite layer thicknesses in the 2.5–4 μm range, which is smaller than the usual thickness of the oxygen inhibition layer (OIL) commonly present in these types of resins. Optimization of these technological processes and parameters to control film thickness and consistency is discussed in detail. Full article

A kind of magnetoplasmonic resonators is numerically designed with hexagonally arrayed Au/bismuth iron garnet (BIG) bilayer nanodiscks on Au thin film layers. Multi-physics coupling calculation on their magnetoplasmonic resonance features suggest that there exists a strong resonant coupling between the surface plasmon excited by the hexagonal grating and the waveguide modes induced by Au-BIG-Au, which can significantly enhance the transverse magneto-optical Kerr effect. Interestingly, a new type of circular oscillating can be induced in the optical-transparent BIG layers as the thickness of BIG layers is between 2 nm and 22 nm. This circular oscillating exhibits a distinct thickness-dependent feature, which can be attributed to the near field interference of the excited localized plasmon resonance between the two interfaces formed by the middle BIG nanodiscs in the top Au nanodisks and the bottom Au thin film layers according to the simulation. These unique magnetoplasmonic features endow this kind of magnetoplasmonic resonators with a greatly enhanced refractive index sensing property, with a calculated figure of merit (FOM) value of up to 7527 RIU⁻¹. Full article

Background/Objectives: Extracellular vesicles (EVs) are nanoscale, membrane-enclosed structures that play key roles in intercellular communication and biological regulation. Among them, Lactobacillus paracasei-derived EVs (Lp-EVs) have attracted attention for their anti-inflammatory and anti-aging properties, making them promising candidates for therapeutic and cosmetic use. However, methods for specific detection and quantitative evaluation of Lp-EVs are still limited. This study aims to develop a surface plasmon resonance (SPR)-based sensor system for the precise and selective detection of Lp-EVs. Methods: Anti-p40 antibodies were immobilized on gold thin films to construct an SPR sensing platform. The overexpression of the p40 protein on Lp-EVs was confirmed using flow cytometry and Western blotting. For functional evaluation, Lp-EVs were applied to an artificial skin membrane mounted on a Franz diffusion cell, followed by SPR-based quantification and fluorescence imaging to assess their skin penetration behavior. Results: The developed SPR sensor demonstrated high specificity and a detection limit of 0.12 µg/mL, with a linear response range from 0.1 to 0.375 µg/mL. It successfully discriminated Lp-EVs from other bacterial EVs. In the skin diffusion assay, Lp-EVs accumulated predominantly in the epidermal layer without penetrating into the dermis, likely due to their negative surface charge and interaction with the hydrophobic epidermal lipid matrix. Fluorescence imaging confirmed this epidermal confinement, which increased over 24 h. Conclusions: This study presents a sensitive and selective SPR-based platform for detecting Lp-EVs and demonstrates their potential for targeted epidermal delivery. These findings support the use of Lp-EVs in skin-focused therapeutic and cosmetic applications. Future studies will explore strategies such as microneedle-assisted delivery to enhance transdermal penetration and efficacy. Full article

This study examines the impact of Au nanoparticles (Au-NPs) on the chemoresistive gas sensing properties as a function of particle size. The sensing material is composed of ultrathin CuO/Cu₂O films, which are fabricated by either thermal deposition technology or spray pyrolysis. These are used on a silicon nitride (Si₃N₄) micro hotplate (µh) chip with Pt electrodes and heaters. The gas sensing material is then functionalised with Au-NP of varying sizes (12, 20, and 40 nm, checked by transmission electron microscopy) using drop coating technology. The finalised sensors are tested by measuring the electrical resistance against various target gases, including carbon monoxide (CO), carbon dioxide (CO₂), and a mixture of hydrocarbons (HC_Mix), in order to evaluate any cross-sensitivity issues. While the sensor response is markedly contingent on the structural surface, our findings indicate that the dimensions of the Au-NPs exert a discernible influence on the sensor’s behaviour in response to varying target gases. The 50 nm thermally evaporated CuO/Cu₂O layers exhibited the highest sensor response of 78% against 2000 ppm CO₂. In order to gain further insight into the surface of the sensors, a scanning electron microscope (SEM) was employed, and to gain information about the composition, Raman spectroscopy was also utilised. Full article