Search Results (85)

Thai fermented soybeans (TFSs) contain phytochemicals with anti-diabetic benefits. In this study, an initial non-optimized TFS extract (TFSE) was prepared using a conventional triplicate 80% ethanol extraction method and evaluated for its biological activity. TFSE effectively reversed TNF-α-induced insulin resistance in 3T3-L1 adipocytes by enhancing insulin-stimulated glucose uptake, indicating anti-diabetic potential. TFSE also upregulated the phosphorylation of AKT (a key insulin signaling mediator) and the expression of adipogenic proteins (PPARγ, CEBPα) in TNF-α-exposed 3T3-L1, suggesting the mitigation of adipocyte dysfunction; however, the results did not reach statistical significance. The conventional extraction process was labor-intensive and time-consuming, and to enhance extraction efficiency and bioactivity, the process was subsequently optimized using environmentally friendly microwave-assisted extraction (MAE) in combination with the Box–Behnken design (BBD) and response surface methodology (RSM). The optimized extract (O-TFSE) was obtained over a significantly shorter extraction time and exhibited higher levels of total flavonoids and antioxidant activity in comparison to TFSE, while showing reduced levels of isoflavones (daidzein, genistein, and glycitein) in relation to TFSE. Interestingly, O-TFSE retained similar efficacy in reversing TNF-α-induced insulin resistance and demonstrated significantly stronger α-glucosidase and α-amylase inhibitory activities, indicating its enhanced potential for diabetes management. These results support the use of MAE as an efficient method for extracting functional compounds from TFS for functional foods targeting insulin resistance and type 2 diabetes mellitus. Full article

Polyimide, a class of high-performance polymers, is renowned for its exceptional thermal stability, mechanical strength, and chemical resistance. However, in the context of high-integration and high-frequency electronic packaging, polyimides face critical challenges including relatively high dielectric constants, inadequate thermal conductivity, and mechanical brittleness. Recent advances have focused on molecular design and composite engineering strategies to address these limitations. This review first summarizes the intrinsic properties of polyimides, followed by a systematic discussion of chemical synthesis, surface modification approaches, molecular design principles, and composite fabrication methods. We comprehensively examine both conventional polymerization synthetic routes and emerging techniques such as microwave-assisted thermal imidization and chemical vapor deposition. Special emphasis is placed on porous structure engineering via solid-template and liquid-template methods. Three key modification strategies are highlighted: (1) surface modifications for enhanced hydrophobicity, chemical stability, and tribological properties; (2) molecular design for optimized dielectric performance and thermal stability; and (3) composite engineering for developing high-thermal-conductivity materials with improved mechanical strength and electromagnetic interference (EMI) shielding capabilities. The dielectric constant of polyimide is reduced while chemical stability and wear resistance can be enhanced through the introduction of fluorine groups. Ultra-low dielectric constant and high-temperature resistance can be achieved by employing rigid monomers and porous structures. Furthermore, the incorporation of fillers such as graphene and boron nitride can endow the composite materials with high thermal conductivity, excellent EMI shielding efficiency, and improved mechanical properties. Finally, we discuss representative applications of polyimide and composites in electronic device packaging, EMI shielding, and thermal management systems, providing insights into future development directions. Full article

Measuring pH is a critical parameter in environmental monitoring, biomedical diagnostics, food safety, and industrial processes. Optical fiber sensors have proven highly effective for pH detection due to their exceptional sensitivity, rapid response, and resistance to electromagnetic interference, making them well suited for real-time monitoring. This review offers a comprehensive analysis of recent advances in optical fiber-based pH sensors, covering key techniques such as fluorescence-based, absorbance-based, evanescent wave, and interferometric methods. Innovations in Fiber Bragg Grating and Surface Plasmon Resonance technologies are also examined. The discussion extends to the impact of pH-sensitive coatings—ranging from nanomaterials and polymeric films to graphene-based compounds—on enhancing sensor performance. Recent advancements have also enabled automation in data analysis and improvements in remote sensing capabilities. The review further compares the economic viability of optical fiber sensors with traditional electrochemical methods, while acknowledging persistent issues such as temperature cross-sensitivity, long-term stability, and fabrication costs. Overall, recent developments have broadened the functionality and application scope of these sensors by improving efficiency, accuracy, and scalability. Future research directions are outlined, including advanced optical interrogation techniques, such as Addressed Fiber Bragg Structures (AFBSs), microwave photonic integration, and optimized material selection. These approaches aim to enhance performance, reduce costs, and enable the broader adoption of optical fiber pH sensors. Full article

Investigations of the synthesis of multicomponent coatings and their subsequent application to metal substrates to increase the wear resistance of materials is relevant for industry. Nickel compounds obtained from oxidized magnesia-iron nickel ores with a desorption rate of more than 94% were used to create Ni-MoO₃-WO₃ electroplating. Such composite samples formed from an aqueous alcohol solution reduced the content of sodium and ammonium chlorides. The annealing and dehydration of samples at a temperature of 725 °C in an air atmosphere made it possible to achieve the highest level of crystallinity. In this case, an isomorphic substitution of W atoms by Mo occurs, which is confirmed by electron paramagnetic resonance (EPR) spectroscopy studies. The invariance of the shape of the EPR spectrum with a sequential increase in microwave radiation power revealed the stability of the bonds between the particles. The surface morphology of Ni-MoO₃-WO₃ films deposited on an Al substrate is smooth and has low roughness. In this case, an increased degree of wear resistance has been achieved. Thus, a recipe for the formation of an electroplating with stable bonds between the components and increased wear resistance was obtained. Full article

This paper proposes a structural silicon heterojunction photosensitive element with a simple form, low manufacturing cost, and efficient performance, which has a high-intensity photoelectric effect and a high frequency range of use. It can be applied as microwave switches to active frequency selective surfaces (AFSSs) to replace PIN diodes. Meanwhile, we explore the crucial role of pentacene/silicon heterojunction in the photoelectric conversion process. It is found that due to the inherent photovoltaic effect and the built-in electric field interaction between the two materials, the insertion loss of the heterojunction formed is reduced to 4.5 dB, which is 2.5 dB lower than that of the high-resistivity silicon wafer. In order to further reduce the insertion loss, the surface of the silicon wafer is etched and then heterojunction is prepared, which can further reduce insertion loss to within 2.5 dB, and the bandwidth difference between the presence and absence of pump excitation exceeds 10 dB extends to 12 GHz, indicating that the light collecting ability of structural silicon significantly enhances its photoelectric effect. The research results demonstrate the potential of using structural silicon heterojunctions in photoelectric devices, providing new technology for high-performance microwave switches and implementing optically controlled FSSs. Full article

Asphalt pavements face escalating challenges from traffic loading, climate change, and material degradation, necessitating innovative maintenance solutions. Thermally induced self-healing technologies, leveraging the viscoelastic properties of asphalt binders, can autonomously repair microcracks through targeted thermal activation. This review explored thermally induced self-healing in asphalt mixtures, with a focus on leveraging steel slag as a functional aggregate to enhance sustainability and durability. Two thermal-activation methods, electromagnetic induction and microwave heating, were critically analyzed, highlighting their distinct advantages in heating efficiency, depth, and uniformity. Steel slag offers dual benefits: improving mechanical interlock and skid resistance in mixtures while facilitating efficient heat generation via electromagnetic induction or microwave heating. However, challenges such as hydration-induced expansion, heterogeneous slag composition, and energy-intensive heating processes impede widespread adoption. Pretreatment methods, including natural aging, carbonation, and surface modifications, are essential to mitigate volumetric instability and optimize slag performance. Key factors influencing healing efficacy, including binder properties, operational parameters (e.g., microwave power, frequency), and environmental trade-offs, were systematically evaluated. Future research directions emphasized standardized pretreatment protocols, hybrid heating technologies for uniform temperature distribution, and smart-infrastructure integration for predictive maintenance. Full article

In this work, a biochar catalyst was developed from residual brewery spent grain (BSG) biomass and iron oxide to be applied in the counter electrode (CE) in dye-sensitized solar cells (DSSCs). The composite was obtained using a two-stage methodology based on microwave-assisted hydrothermal carbonization and pyrolysis, evaluating the influence of the pyrolysis temperature (700, 800 and 900 °C) on the properties and performance of the material. As result, composites with a high carbon and iron oxide content were obtained in a magnetite state attached to the surface. Furthermore, the physicochemical characteristics of the biochar showed similarities to those of reduced graphene oxide (rGO), which was attributed to the incorporation of iron oxide and the pyrolysis temperature. Electrochemical analysis showed that the composite pyrolyzed at 800 °C presented better catalytic activity and lower charge transfer resistance. Its application in the CE of a DSSC presented a current density of 10.44 mA/cm² and an efficiency of 3.05%, values close to the conventional Pt catalyst in DSSCs (Pt = 4.43%). This study validates the use of a composite based on residual brewery biomass with iron oxide in a CE, making it an alternative that contributes to the recovery of residues and the generation of sustainable technologies. Full article

In this work, room-temperature UV-assisted ozone detection was investigated using ZnO nanoplates synthesized via precipitation, ultrasound-, ultrasonic tip-, and microwave-assisted hydrothermal (MAH) methods. X-ray diffraction confirmed the formation of crystalline phases with an ~3.3 eV band gap, independent of the synthesis used. Raman spectroscopy revealed oxygen-related defects. Plate-like morphologies were observed, with the ultrasonic tip-assisted synthesis yielding ~17 nm-thick plates. Electrical measurements showed 10–170 ppb ozone sensitivity under UV. The sample synthesized via the MAH method (ZM) demonstrated superior conductance, with a baseline resistance of ~1.2% for the ultrasound (ZU) sample and less than 50% for the precipitation (ZA) and ultrasonic tip (ZP) samples. Despite the appreciable response in dark mode, the recovery was slow (>>30 min), except for the UV illumination condition, which reduced the recovery response to ~2 min. With top areas of ~0.0122 µm², ZP and ZU showed high specific surface areas (24.75 and 19.37 m²/g, respectively), in contrast to ZM, which exhibited the lowest value (15.32 m²/g) with a top area of ~0.0332 µm² and a thickness of 26.0 nm. The superior performance of ZM was attributed to the larger nanoplate sizes and the lower baseline resistance. The ultrasound method showed the lowest sensitivity due to the higher resistance and the depletion layer effect. The results indicate that the synthesis methods presented herein for the production of reactive ZnO nanoplates using NaOH as a growth-directing agent are reliable, simple, and cost-effective, in addition to being capable of detecting ozone with high sensitivity and reproducibility at concentrations as low as 10 ppb. Full article

The setae structure of geckos’ toes can create a strong adhesion force, allowing geckos to climb almost vertical walls. Inspired by this, carbon nanotubes–graphite (CNTs-Gr) was prepared by microwave technology, where CNTs like the setae structure grew in situ on the surface of Gr flakes. Compared to the Gr, the coefficient of friction (COF) and wear rate of CNTs-Gr decreased by 44% and 46%, reaching 0.10 and 1.18 × 10⁻⁵ mm³·N⁻¹·m⁻¹, respectively. Even if the load increased from 5 N to 35 N, the CNTs-Gr maintained a low and stable COF of 0.12. The excellent tribological properties were attributed to the unique setae structure of CNTs-Gr. This structure enabled the adhesion force of CNTs-Gr to the worn surface to increase threefold, improving the coverage of the lubricating film and significantly enhancing the lubricating film’s pressure resistance. The gecko setae structure proposed in this article provides researchers with a new idea for designing lubricants with excellent lubrication performance and high load-bearing capacity. Full article

A rapid microwave-assisted process minimizing waste was set up to produce bio-based benzoxazine-like monomers produced from vanillylamine and melamine. Without excessive purification, different viscous liquid precursors had a remarkable ability to form four strong and transparent different solid cross-linked thermosets, displaying lower curing temperatures under 130 °C. The long and strong adhesive performance of the cured materials was observed using glass slides or aluminum surfaces and they could become a good alternative to adhesive epoxy resin for metal surfaces. At the higher temperatures, these solids could act as efficient flame-retardants proven by thermogravimetric measurements. The best candidates gave a limiting oxidation index value of 41.9. In order to improve the intrinsic surface hydrophobicity of the phenolic resins, slight amounts of silica and iron oxide nanoparticles were dispersed in the polymer matrix, and finally mechanical resistance was pointed out. The most promising of our melamine-based resin was loaded with aluminum pigment to furnish a silver-colored paste ready for being cured to afford a robust solid, which does not undergo contraction or deformation. Full article

Microwave-assisted synthesis presents a promising method for enhancing the formation of nanocomposites due to its rapid heating and uniform energy distribution. In this study, we successfully fabricated polyethersulfone–zinc-oxide (PES-ZnO) nanocomposite membranes by exposing PES/ZnCl₂/DMF dope solutions to microwave radiation. Before synthesizing the membranes, zinc-oxide nanoparticles (ZnO-NPs) were optimized in an organic phase using microwave radiation to ensure effective nanoparticle formation. The synthesis of ZnO-NPs in DMF solvent was validated through UV–Vis spectroscopy, X-ray diffraction (XRD), and Dynamic Light Scattering (DLS). We examined the surface morphology and roughness of the PES-ZnO membranes through Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Moreover, we assessed the membranes’ hydrophilicity, permeability, and physicochemical properties through contact-angle measurements, pure water flux tests, water uptake assessments, and porosity tests. Energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) verified the successful integration of ZnO nanoparticles (ZnO-NPs) into the membrane matrix. The results indicate that including ZnO-NPs significantly improves the membrane’s permeability and hydrophilicity. The nanocomposite membranes exhibited high dye rejection efficiency, with ZnO-NPs facilitating photocatalytic self-cleaning properties. Antibacterial tests also demonstrated a substantial inhibition of common bacteria, suggesting enhanced resistance to biofouling. This research highlights the potential of microwave-assisted PES-ZnO nanocomposite membranes as effective and sustainable solutions for wastewater treatment, offering scalable applications along with added benefits of antifouling, self-cleaning, and antibacterial properties. Full article

This study proposes a frequency-selective absorber (FSA) with dual passbands and wide-angle oblique incidence. The design consists of a circuit analog (CA) sheet and a dual-bandpass frequency selective surface (FSS) sheet, both embedded in dielectric slabs separated by a foam spacer. The CA sheet unit cell is based on a tripole loaded with multiple shorted transmission lines and lumped resistors. In this way, the performance of the CA sheet is equivalent to a resistive sheet in a low-frequency band and a transparent sheet in two high-frequency bands. By comprehensively designing the CA sheet and the dual-bandpass FSS sheet, we created an FSA structure that exhibits microwave absorption in the band from 2.6 GHz to 9.2 GHz with a reflectivity lower than −10 dB. It also possesses transmission in the 12.2–15.1 GHz and 30.6–31.5 GHz bands, with a transmittance greater than −3 dB in both. In addition, the FSA structure provides a stable transmission response of up to 60° of oblique incidence and absorption performance of up to 45° of oblique incidence in TE and TM polarization. A 400 × 400 mm flat FSA sample was fabricated, was measured, and is discussed. The experimental results are consistent with the simulation results, proving that the proposed FSA design holds great potential for applications in dual-frequency low-scattering radomes with high curvature and multi-directional electromagnetic interference suppression. Full article

With the development of diamond technology, its application in the field of electronics has become a new research hotspot. Hydrogen-terminated diamond has the electrical properties of P-type conduction due to the formation of two-dimensional hole gas (2DHG) on its surface. However, due to various scattering mechanisms on the surface, its carrier mobility is limited to 50–200 cm²/(Vs). In this paper, the effects of process parameters (temperature, CH₄ concentration, time) on the electrical properties of hydrogen-terminated diamond were studied by microwave plasma chemical vapor deposition (CVD) technology, and hydrogen-terminated diamond with a high carrier mobility was obtained. The results show that homoepitaxial growth of a diamond film on a diamond substrate can improve the carrier mobility. Hydrogen-terminated diamond with a high carrier mobility and low sheet resistance can be obtained by homoepitaxial growth of a high-quality diamond film on a diamond substrate with 4% CH₄ concentration and hydrogen plasma treatment at 900 ℃ for 30 min. When the carrier concentration is 2.03 × 10¹²/cm², the carrier mobility is 395 cm²/(Vs), and the sheet resistance is 7.82 kΩ/square, which greatly improves the electrical properties of hydrogen-terminated diamond. It can enhance the transmission characteristics of carriers in the conductive channel, and is expected to become a potential material for application in devices, providing a material choice for its application in the field of semiconductor devices. Full article

Volatile and semi-volatile compounds, such as petroleum hydrocarbons and equipment lubricating oils, often contaminate soil due to accidents, posing significant ecological and health risks. Traditional soil remediation methods, such as thermal desorption and bioremediation, are time-consuming and resource-intensive, prompting researchers to explore more efficient alternatives. This study investigates the effectiveness of an in situ reactor for microwave-assisted soil remediation, specifically focusing on the impact of soil type and moisture content on pollutant removal efficiency. The reactor, designed to operate within a modified household microwave oven, provides direct microwave irradiation to the soil surface, enabling precise control of heating conditions. Experiments were conducted using soil samples of varying particle sizes and moisture levels under standardized conditions (1000 W microwave power, 2.45 GHz frequency). The results show that moisture content plays a critical role in pollutant removal efficiency, with an optimal moisture content of 10 wt % enhancing microwave absorption and energy transfer, thus improving pollutant recovery. In comparison with traditional resistive heating, microwave heating achieved a faster temperature rise and higher final temperatures, significantly improving pollutant removal efficiency in a shorter time frame. This study highlights the advantages of microwave heating, including its superior energy efficiency, faster pollutant volatilization, and the potential for optimized soil remediation in real-world applications. These findings provide valuable insights for the development of more sustainable and efficient soil remediation technologies. Full article

The growing demand for clean, decentralized energy has increased interest in blue energy, which generates power from water with different salt concentrations. Despite its potential as a renewable, low-cost energy source, optimizing electrode materials remains a challenge. This work presents a nanomaterial developed via microwave-assisted sol-gel methodology for blue energy applications, where ion diffusion and charge storage are critical. AX-7 carbon, designed for this study, features wide pores, enhancing ion diffusion. Compared to commercial NORIT carbon, AX-7 has a higher mesopore volume and external surface area, improving its overall performance. The synthesis process has been optimized and scaled up for evaluation in CAPMIX electrochemical cell stacks. Moreover, the lower series resistance (Rs) significantly boosts energy recovery, with AX-7 demonstrating superior performance. This advantage is especially evident during fresh-water cycles, where this material achieves significantly lower Rs compared to the commercial one. Full article