Search Results (18)

Lactarius deliciosus is a widely distributed edible mushroom valued as a functional food due to its rich content of nutrients, phenolic compounds, and flavonoids, which contribute to its strong antioxidant and antimicrobial properties. The present study aimed to optimize a green microwave-assisted extraction method for maximal recovery of bioactive phenolic compounds from Lactarius deliciosus extract (LDE) and to evaluate its antioxidant, antiproliferative, antimetastatic, and anti-inflammatory effects on human colon carcinoma (Caco-2) cells. The study demonstrated that solvent polarity and composition critically influence the recovery of antioxidant biomolecules, identifying water and NaDES 1 (glycerol/glycine/water) as the most efficient and sustainable solvents for microwave-assisted extraction at 225 °C. The LDE showed high levels of phenolic compounds—particularly 4-hydroxybenzoic and vanillic acids—indicating potent antioxidant potential and possible anticancer efficacy. The results revealed that the LDE significantly reduced colony formation and cell adhesion in a dose-dependent manner, leading to nearly complete inhibition of clonogenic survival at the IC₅₀ concentration and a marked increase in cell death among non-adherent colon cancer cells. In addition, LDE inhibited the proliferation of Caco-2 cells by inducing G0/G1 cell cycle arrest and apoptosis, associated with altered mitochondrial potential and increased caspase-3 activity. The LDE modified the redox balance of the cell by decreasing the ROS levels and exerts anti-inflammatory effects through significant downregulation of NOS2 expression, without adversely affecting the intestinal barrier. The study concludes that LDE bioactive compounds show strong promise as anticancer and functional ingredients, demonstrating antioxidant, antiproliferative, antimetastatic, and anti-inflammatory effects. Full article

Eugenol is the key bioactive compound in clove oil, which has a variety of biological functions and is extensively employed in the medicinal and food industries. Nowadays, deep eutectic solvents (DESs) have received considerable attention as green solvents that enhance extraction efficiency. The present study investigated the effects of DESs on the eugenol composition in clove essential oils (CEOs) extracted from clove buds using ultrasonic- and microwave-assisted hydrodistillation techniques. The study revealed that both DES-based microwave-assisted hydrodistillation (DES-MHD) and ultrasonic-assisted DES pretreatment followed by microwave-assisted hydrodistillation (U-DES-MHD) significantly enhanced the eugenol purity in CEOs compared to the MHD method without the use of DESs. The great CEOs with a high amount of eugenol obtained via choline chloride–oxalic acid (ChCl-OA) at a 1:2 molar ratio were used as DESs. Their oils had a eugenol content of 82.90% and 83.34%, respectively, corresponding to the extraction by DES-MHD and U-DES-MHD methods, which were raised from the oil’s extraction without DES by MHD 7.42% and 8.36%, respectively. Corresponding to a strong antioxidant agent of eugenol, the oils extracted by ChCl-OA-based MHD and ultrasonic-assisted ChCl-OA-based MHD methods had significantly stronger DPPH radical scavenging activity with an IC₅₀ level of 2.16 ± 0.11 and 2.19 ± 0.05 μg/mL, respectively, than the oils extracted without DESs. Hence, these innovative processes offer a promising approach to improving the bioactivity of clove oils, while providing straightforward operation and environmentally friendly extraction methods. Additionally, these novel processes may find application in other edible essential oil extractions for the food and pharmaceutical industries. Full article

In areas where there is high humidity and freezing rain, there is a tendency of blade icing on wind turbines. It results in energy dissipation and mechanical abrasion and also creates a safety concern due to the risk of having falling ice. Real-time online detection of icing is crucial in the enhancement of power generation efficiency and in the safety of wind turbines. The current methods of icing detection that use ultrasound, optics, vibration, and electromagnetics are already studied. But these methods have their drawbacks, including small detection ranges, low accuracy, large size, and challenges in distributed installation, making it hard to capture the real-time dynamics of the icing and de-icing processes on the wind turbine blades. To this end, this paper presents a new blade surface icing detection technique using microstrip lines. This approach uses the impact of icing state and thickness on the effective dielectric constant of the microstrip line surface. This paper presents the analysis of time-domain features of microwave signals, which facilitates the identification of both the icing state and the corresponding thickness. Simulation and experimental measurement of linear and S-shaped microstrip sensors are used in this research in order to compare the response of the sensors to the variation in the thickness of the icing layer. It is seen that for icing thickness ranging from 0 mm to 6 mm, the imaginary part of the S21 parameter of the S-shaped microstrip line has a more significant change than that of the linear microstrip line. The above experiments also confirm that the phase shift value of the S-shaped microstrip line is always higher than that of the linear microstrip line for the same variation of icing thickness, which proves that the S-shaped microstrip line is more sensitive than the linear one. Also, it was possible to establish the relationship between the phase shift values and icing thickness, which makes it possible to predict the icing thickness. The developed microwave microstrip detection technology is intended for usage in the wind turbine blade icing and similar surface detection areas. This method saves the size and thickness of icing sensors, which makes it possible to conduct measurements at various points. This is especially beneficial for usage in wind turbine blades and can be further applied in aerospace, automotive, and construction, especially the bridges. Full article

Brewer’s spent grains (BSG) offer valuable opportunities for valorization beyond its conventional use as animal feed. Among its components, lignin—a natural polymer with inherent antioxidant properties—holds significant industrial potential. This work investigates the use of microwave-assisted extraction combined with acidic natural deep eutectic solvents (NaDESs) for efficient lignin recovery, evaluating three different NaDES formulations. The results indicate that choline chloride–lactic acid (ChCl-LA), a NaDES with superior thermal stability as confirmed via thermogravimetric analysis (TGA), is an ideal solvent for lignin extraction at 150 °C and 15 min, achieving a balance of high yield and quality. ChCl-LA also demonstrated good solubility and cell disruption capabilities, while microwaves significantly reduced processing time and severity. Under optimal conditions, i.e., 150 °C, 15 min, in the presence of ChCl-LA NaDES, the extracted lignin achieved a purity of up to 79% and demonstrated an IC50 (inhibitory concentration 50%) of approximately 0.022 mg/L, indicating a relatively strong antioxidant activity. Fourier transform infrared (FTIR) and 2D-HSQC NMR (heteronuclear single quantum coherence nuclear magnetic resonance) spectroscopy confirmed the successful isolation and preservation of its structural integrity. This study highlights the potential of BSG as a valuable lignocellulosic resource and underscores the effectiveness of acidic NaDESs combined with microwave extraction for lignin recovery. Full article

The application of microwave de-icing technology in road engineering is constrained by its low energy utilization rate, which can be attributed to low heat production rates and ineffective heat dissipation to the underlying pavement. In this work, asphalt mixtures are designed as an upper layer (heating layer) and a lower layer (thermal-resistance layer). Magnetite slag was selected as a microwave-sensitive source for generating heat, and expanded perlite powder was incorporated into the lower layer as a thermal resistance material. Structural layer optimization and thermal-resistance layer design of the asphalt mixture were carried out by changing the thickness of the upper and lower layers to further improve the heat production rates. The design effectiveness is comprehensively evaluated by factors such as the changing law of the average surface temperature of mixtures, ice-melting time, and cost-effectiveness analyses. The results show that EP possesses better thermal stability, lower microwave energy conversion ability and more excellent heat-resistance potential compared with mineral powder. The heat-resistance layer with EP can prevent heat from being conducted to the lower layer and promote it to concentrate on the specimen surface, which can endow the microwave heating efficiency of specimens to be further improved by up to 26.97% and the de-icing time reduced by 10%, ascribed to the heat-resistance design. Furthermore, the collaborative design of the structural layer optimization and heat-resistance layer can increase energy utilization efficiency and save microwave-absorbing materials while ensuring excellent microwave de-icing efficiency. Full article

The combination of an absorbing structure and a road is a promising strategy for road deicing using microwaves. In this study, cement mortar (CM) specimens containing a carbon fiber screen (CFS) were prepared to concentrate electromagnetic losses on a road surface. The effect of the size and depth of the CFS on the surface heating efficiency of the microwave was studied and optimized, and a microwave deicing experiment was conducted. The results indicated that the destructive interference produced by the CFS led to the effective surface heating of the CM/CFS specimens. The optimal surface heating rate was 0.83 °C/s when the spacing, depth, and width of the CFS were 5.22, 13.31, and 2.80 mm, respectively. The deicing time was shortened by 21.68% from 83 to 65 s, and the heating rate increased by 17.14% from 0.70 to 0.82 °C/s for the specimen with CFS-1, which was 15 mm depth. Our results demonstrate that CM/CFS composite structures can be effectively applied to increase the capacity and accelerate the development of the microwave deicing of roads. Full article

Nowadays, plant-based bioactive compounds (BCs) are a key focus of research, supporting sustainable food production and favored by consumers for their perceived safety and health advantages over synthetic options. Lavandula pedunculata (LP) is a Portuguese, native species relevant to the bioeconomy that can be useful as a source of natural BCs, mainly phenolic compounds. This study compared LP polyphenol-rich extracts from conventional maceration extraction (CE), microwave and ultrasound-assisted extraction (MAE and UAE). As a result, rosmarinic acid (58.68–48.27 mg/g DE) and salvianolic acid B (43.19–40.09 mg/g DE) were the most representative phenolic compounds in the LP extracts. The three methods exhibited high antioxidant activity, highlighting the ORAC (1306.0 to 1765.5 mg Trolox equivalents (TE)/g DE) results. In addition, the extracts obtained with MAE and CE showed outstanding growth inhibition for B. cereus, S. aureus, E. coli, S. enterica and P. aeruginosa (>50%, at 10 mg/mL). The MAE extract showed the lowest IC₅₀ (0.98 mg DE/mL) for angiotensin-converting enzyme inhibition and the best results for α-glucosidase and tyrosinase inhibition (at 5 mg/mL, the inhibition was 87 and 73%, respectively). The LP polyphenol-rich extracts were also safe on caco-2 intestinal cells, and no mutagenicity was detected. The UAE had lower efficiency in obtaining LP polyphenol-rich extracts. MAE equaled CE’s efficiency, saving time and energy. LP shows potential as a sustainable raw material, allowing diverse extraction methods to safely develop health-promoting food and nutraceutical ingredients. Full article

The purpose of this study was to propose a highly efficient, durable, and environmentally friendly method for the rapid removal of ice and snow. A microwave-absorbing functionality layer was placed between a conductive metal mesh and magnetite sand shielding layer, and ordinary cement concrete (OC). Microwave heating, mechanical strength determination, and indoor and outdoor de-icing tests were performed on the cement concrete specimens with the shielding layer. Basalt fibers were added to the absorbing functionality layer, and the formed specimens were tested for strength and durability. The microstructure was observed using SEM experiments. The results show that the temperature rise of microwave-absorbing cement concrete with a magnetite sand shielding layer (MCMS) and microwave-absorbing cement concrete with a conductive metal mesh shielding layer (MCMM) increased by approximately 17.2% and 27.1%, respectively, compared to that of microwave-absorbing concrete (MAC). After freeze–thaw cycles, the compressive strength and flexural strength of microwave-absorbing concrete with basalt fiber (MAB) increased by 4.35% and 7.90% compared to those of MAC, respectively. The compressive strength and flexural strength of microwave-absorbing concrete with a magnetite sand shielding layer and basalt fiber (MAMB) increased by 8.07% and 6.57%, respectively, compared to those of MCMS. Compared to specimens without basalt fiber, the wear rate per unit area of MAMB decreased by 8.8%, and the wear rate of MAB decreased by 9.4%. The water absorption rate of MAMB specimens decreased by 13.1% and 12.0% under the conditions of 20 and 40 microwave freeze–thaw cycles, respectively, compared to that of MCMS. The water absorption rate of MAB specimens decreased by 9.9% and 8.3% under the conditions of 20 and 40 microwave freeze–thaw cycles, respectively, compared to that of MAC. SEM analysis showed that the addition of basalt fibers improved the compactness and stability of the cement concrete structure as a whole. This study provides valuable references for the promotion and application of microwave de-icing technology. Full article

Microwave heating technology is a promising method for asphalt pavement maintenance and de-icing; however, it requires the material to have a good microwave-absorbing ability and can also result in asphalt aging. It is therefore important to develop microwave-sensitive materials used for asphalt pavement maintenance and study the effects of microwave heating on asphalt aging. This study evaluates the electromagnetic characteristics of limestone powder and magnetite powder and explores the influence of microwave heating on the high-temperature rheological and fatigue properties of microwave sensitivity enhanced asphalt mastic with magnetite powder. A vector network analyzer was used to measure the electromagnetic characteristics of limestone powder and magnetite powder. The magnetite filler asphalt mastics were prepared and subjected to microwave heating for 1 h, 2 h, 3 h, and 4 h. Temperature sweep tests, frequency sweep tests, and linear amplitude sweep (LAS) tests were conducted for magnetite filler asphalt mastics before and after microwave heating. LAS experimental results were analyzed based on viscoelastic continuum damage (VECD) theory. The results show that magnetite powders have better electric field energy storage ability, higher dielectric loss and magnetic loss, and better microwave heating efficiency. The complex shear modulus (G*) and rutting factor (G* × (sin δ)⁻¹) rapidly decrease with the increase in temperature, indicating that the mastics’ ability to resist deformation decreases sharply. The longer the microwave heating time for magnetite filler asphalt mastics, the faster the high-temperature rheological properties decreased as the temperature rose. The fatigue life of magnetite filler asphalt mastics significantly decreases with the increase in strain and microwave heating time. It is suggested to add anti-aging agents into asphalt materials to reduce the aging effect in the process of microwave heating. This study provides a reference for the application of microwave heating technology in asphalt pavement maintenance. Full article

Microwave heating is widely employed in pavement deicing. However, it is difficult to improve the deicing efficiency because only a small part of the microwave energy is used and most of it is wasted. To improve the utilization efficiency of microwave energy and the deicing efficiency, we used silicon carbide (SiC)–replaced aggregates in asphalt mixtures to prepare an ultra-thin, microwave-absorbing wear layer (UML). The SiC particle size, SiC content, oil–stone ratio and thickness of the UML were determined. The effect of the UML on energy saving and material reduction was also evaluated. Results show that only a 10 mm UML was needed to melt a 2 mm ice layer within 52 s at −20 °C and rated power. In addition, the minimum layer thickness to meet the specification requirement (≥2000 με) of asphalt pavement was also 10 mm. SiC with larger particle sizes increased the temperature rise rate but decreased the temperature uniformity, instead increasing the deicing time. The deicing time of a UML with SiC particle size less than 2.36 mm was 35 s shorter than that of a UML with SiC particle size greater than 2.36 mm. Furthermore, more SiC content in the UML resulted in a higher temperature rise rate and less deicing time. The temperature rise rate and deicing time of the UML with 20% SiC were 4.4 times and 44% of those of the control group. When the target void ratio was 6%, the optimum oil–stone ratio of UML was 7.4%, and it had good road performance. Compared to overall heating, the UML saved 75% of power and SiC material under the same heating efficiency. Therefore, the UML reduces microwave deicing time and saves energy and material. Full article

In the past decades, a large amount of research was conducted to investigate the application prospect of microwave heating technology in improving the efficiency of asphalt pavement self-healing and de-icing. This paper reviewed the achievements in this area. Firstly, the properties of asphalt concrete after microwave heating were summarized, including microwave sensitivity and heating uniformity. Then, the evaluation indicators and influence factors of the self-healing properties of the asphalt mixtures heated by microwave were reviewed. Finally, the application of microwave heating in asphalt pavement de-icing was explored. In addition, asphalt pavement aging due to microwave heating was also reviewed. It was found that microwave heating technology has good prospects in promoting asphalt pavement self-healing and de-icing. There are also some problems that should be studied in depth, such as the cost-effectiveness of microwave-sensitive additives (MSAs), the performance of the pavement with MSAs, mechanism-based self-healing performance indicators, and the aging of asphalt pavements under cycling microwave heating. Full article

Road icing in winter brings challenges to traffic safety, and microwave heating and deicing technology is an effective method with the advantages of high efficiency and environmental protection. Magnetite has been widely used as a microwave-absorbing material in pavement. In this paper, magnetite powder formed by crushing natural magnetite and high-purity Fe₃O₄ powder after purification were mixed to replace mineral powder, and the magnetite aggregate was used to replace the limestone aggregate with the same particle size to enhance the asphalt mixtures’ microwave absorption capacity. The effect of microwave heating time and microwave power on the heating of the asphalt mixtures was studied, and the heating performance of different thicknesses of the asphalt mixtures under microwave radiation was evaluated. The heating performance of the mixtures under different initial temperatures and ice layer thicknesses was also assessed. The results showed that the addition of the magnetite powder–Fe₃O₄ powder and the magnetite aggregate significantly enhanced the heating performance of the asphalt mixtures by microwave heating. The replacement of the magnetite powder–Fe₃O₄ powder, the microwave heating time, and the microwave power had positive effects on the heating efficiency of the asphalt mixtures. Moreover, the thinner asphalt mixtures had a better heating performance. The heating and deicing performance of the mixtures decreased with a decline in initial temperature. As the ice thickness increased, the deicing time of the specimen surface to reach 0 °C also increased. Full article

Microwave deicing technology, as a new environmentally friendly deicing technology, can effectively solve the problem of the frequent icing of road surfaces in the winter, which affects the safety of traffic. To improve the efficiency of microwave deicing on cement concrete pavement, this study proposed the use of magnetite, iron sulfide slag, steel slag, lead–zinc slag, and graphite as microwave-absorbing materials, and conducted microwave deicing tests under the influence of five factors, namely the form of the pavement surface structure, the content of the microwave-absorbing material, microwave power, the shielding state, and dry and wet conditions. Layer by layer, we selected the combination of pavement surface structure, microwave-absorbing material content, microwave power, shielding state, and dry and wet conditions on the bottom surface of the concrete slab with the optimal deicing effect. The results showed that the 2 cm scattered microwave-absorbing surface concrete structure has the fastest heating rate; the higher the magnetite content and microwave power, the higher the deicing efficiency; the maximum heating rate can be increased by 17.6% when the shielding layer is set at the bottom of the cement concrete slab; and the heating rate of the microwave-absorbing concrete slab in the wet state is increased by 20.8% relative to the dry state. In summary, 7000 W of power, a magnetite content of 60 vol % in the scattered microwave-absorbing surface, a shielding layer set at the bottom surface, and wet conditions can greatly improve the efficiency of microwave deicing compared with the microwave ice melting effects of plain cement concrete and other microwave-absorbing materials mixed into the concrete. In addition, the temperature uniformity of the microwave-absorbing materials is essential to improve the deicing efficiency of microwave-absorbing concrete, so it is essential to explore it further. Full article

To explore the law of microwave deicing of carbon-fiber-modified concrete under the action of multiple factors and improve its application in pavement, in this study, we designed a test of the heat absorption and deicing effect of concrete under the action of multiple factors. We found that the law of heat absorption and deicing of CFRP is influenced by the coupling effect of fiber length and dosage, height (straight-line distance between the microwave receiving surface and bell component), initial temperature and ice cover. The temperature rises fastest when the fiber dosage is 0.2% and fiber length is 6 mm without ice. Further analysis of other factors shows that the deicing effect is optimal when the height is 40 mm, and the presence of ice on fiber-reinforced concrete weakens the microwave deicing efficiency, although the reduction is small. The test results of these two factors are in agreement with the simulation results and conform to expectations. The initial temperature has a considerable influence on the deicing efficiency. In practical applications, the deicing time should be adjusted according to the initial temperature in order to prevent the phenomenon of secondary icing when the heating time is too long. Based on heat generation and heat dissipation, the four stages of microwave deicing were analyzed, and the relationship with the temperature increase rate was deduced. It was proven that carbon fiber affected the deicing efficiency by changing the microwave absorption and reflection effect of concrete. Full article

This study evaluates the influence of polymer-modification on the induction heating capability of asphalt mastic in a microwave field, and investigates how effectively this approach can be utilized for ice melting and self-healing purposes. To this end, different asphalt mastic mixtures with different polymer-modification and mixing procedures were tested under microwave field exposure for induction heating capability, ice-melting ability, and self-healing capacity. The mixtures were made through warm-mix and hot-mix procedures with four bituminous binders, including virgin (unmodified) asphalt and the same binder modified with three types of polymers. The results showed the effectiveness of microwave induction heating of asphalt mastic for both crack-healing and deicing purposes. The binder type was found to influence the ice melting and crack healing rates, such that using a warm-mix asphalt binder resulted in a more efficient heat generation and conduction than using a virgin asphalt binder. While polymer-modification undermined induction-heating, ice-melting, and self-healing performances, SBS-modified asphalt binders exhibited better performance than the other polymer-modified binders. Full article