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ABSTRACT CuI–Zn(OAc)2 catalyzed a new, fast, solvent‐free strategy for the synthesis of quinazolin‐4(3H)‐ones via selective scission of CC bond of the 1,3‐diketone (both cyclic and acyclic) and β‐ketoester was achieved under microwave irradiation. In contrast to the frequently applied synthetic strategy that involves cyclization‐oxidation sequence of anthranilamides (2‐aminobenzamides) with various aldehydes or benzyl alcohols, here, anthranilamide reacts with β‐ketoester/1,3‐diketo compounds in presence of CuI‐Zn(OAc)2 catalyst to form quinazolin‐4(3H)‐ones scaffold through an uncommon CC bond cleavage under solvent‐free mild conditions with excellent yields. Besides, this method displays its capacity for gram‐scale reactions. [ABSTRACT FROM AUTHOR]

This article presents a physical model that describes the interaction between surface electron beams and plasma. The dispersion relations for beam plasma interactions were derived using perturbation method and field matching methods. The study investigates how different parameters affect radiation frequency and bandwidth. The results indicate that as electron beam velocity increases, the associated kinetic energy also rises, leading to an increase in both the maximum radiation frequency and bandwidth at high frequencies. Conversely, the radiation bandwidth at low frequencies decreases. Similarly, a higher plasma density results in a greater maximum radiation frequency, but the high-frequency bandwidth decreases, while the low-frequency bandwidth increases. Additionally, when the electron density and electron velocity of the electron beam remain constant, increasing the plasma density can increase the microwave radiation frequency However, there exists a plasma density threshold, beyond which high-frequency electromagnetic waves are no longer radiated. [ABSTRACT FROM AUTHOR]

A photonic crystal was created using a magnetic fluid–epoxy resin composite. The amplitude–frequency characteristics of the reflection coefficient of electromagnetic radiation in the microwave range from the resulting structure were experimentally studied. The possibility of using magnetic composites to create controlled photonic crystals was demonstrated. [ABSTRACT FROM AUTHOR]

With the rapid development of the internet of things, the simple preparation of sensors has become a challenge. The present work presents the simple preparation of flexible sensors by using the fused deposition modeling (FDM) 3D printing combined with the microwave radiation‐assisted treatment of the thermoplastic polyurethane (TPU) with carbon nanotubes (CNTs) as conductive fillers to create the flexible sensors. The as‐prepared TPU/CNT composites exhibit the 7.27 MPa tensile strength and 401% elongation at break, similar to those of the pure TPU. After 200 tensile cycles, the TPU/CNT composites can still stably convert pressure into electrical signals, which can be used as flexible sensors with high sensitivity (0.879 kPa−1). In addition, shoe insoles and finger cover with sensing performance are fabricated through the FDM 3D printing technology, demonstrating the potential of the sensors to monitor human gait, finger straightening, and bending movements. The as‐proposed method involves the embedding CNTs as conductive fillers on the surface of TPU to form the TPU/CNT composite conductive layers on the surface of TPU, which is beneficial for maintaining the elasticity of the polymer matrix. The challenges in preparing stable, low‐cost, and scalable flexible sensors and highlights of the advantages of 3D printing technology in manufacturing flexible piezoresistive sensors are also deeply discussed. [ABSTRACT FROM AUTHOR]

To date, microwave radiation has been successfully used to support the chemical hydrolysis of organic substrates in the laboratory. There is a lack of studies on large-scale plants that would provide the basis for a reliable evaluation of this technology. The aim of the research was to determine the effectiveness of using microwave radiation to support the acidic and alkaline thermohydrolysis of lignocellulosic biomass prior to anaerobic digestion on a semi-industrial scale. Regardless of the pretreatment options, similar concentrations of dissolved organic compounds were observed, ranging from 99.0 ± 2.5 g/L to 115.0 ± 3.0 in the case of COD and from 33.9 ± 0.92 g/L to 38.2 ± 1.41 g/L for TOC. However, these values were more than twice as high as the values for the substrate without pretreatment. The degree of solubilisation was similar and ranged between 20 and 28% for both monitored indicators. The highest anaerobic digestion effects, ranging from 99 to 102 LCH4/kgFM, were achieved using a combined process consisting of 20 min of microwave heating, 0.10–0.20 g HCl/gTS dose, and alkaline thermohydrolysis. For the control sample, the value was only 78 LCH4/kgFM; for the other variants, it was between 79 and 94 LCH4/kgFM. The highest net energy gain of 3.51 kWh was achieved in the combined alkaline thermohydrolysis with NaOH doses between 0.10 and 0.20 g/gTS. The use of a prototype at the 5th technology readiness level made it possible to demonstrate that the strong technological effects of the thermohydrolysis process, as demonstrated in laboratory tests to date, do not allow for positive energy balance in most cases. This fact considerably limits the practical application of this type of solution. [ABSTRACT FROM AUTHOR]

Activated carbon has been extensively utilized in a broad spectrum of applications, including catalyst support, energy storage, separation and adsorptive removal of various species. In the synthesis of activated carbon, microwave treatment is a beneficial heating technique for the activation and thermochemical processing of precursors due to various advantages, including uniform heating, shortened processing time, reduced energy consumption and reduced consumption of activating agents. This study aims to present an extensive review on the utilization of common, abundantly available and low-cost biomass wastes to prepare microwave-induced activated carbons and to investigate their dye adsorption characteristics. The methodology for activated carbon synthesis from biowastes, the effects of synthesis conditions, and the influencing factors, such as microwave power level, irradiation time, type of activator, and chemical impregnation ratio, for the efficient adsorption of dyes are discussed. This review highlights the feasibility of using microwave-induced biowaste-derived activated carbons, which supports their potential use as effective and economical dye adsorption materials. [ABSTRACT FROM AUTHOR]

Abstract This article presents a physical model that describes the interaction between surface electron beams and plasma. The dispersion relations for beam plasma interactions were derived using perturbation method and field matching methods. The study investigates how different parameters affect radiation frequency and bandwidth. The results indicate that as electron beam velocity increases, the associated kinetic energy also rises, leading to an increase in both the maximum radiation frequency and bandwidth at high frequencies. Conversely, the radiation bandwidth at low frequencies decreases. Similarly, a higher plasma density results in a greater maximum radiation frequency, but the high-frequency bandwidth decreases, while the low-frequency bandwidth increases. Additionally, when the electron density and electron velocity of the electron beam remain constant, increasing the plasma density can increase the microwave radiation frequency However, there exists a plasma density threshold, beyond which high-frequency electromagnetic waves are no longer radiated.

Microwave ablation is becoming an increasingly important minimally invasive procedure that uses dielectric hysteresis to generate heat and destroy cancer cells. Tissue damage depends on the input power, procedure duration, and antenna position. Therefore, one of the essential problems is determining parameters that ensure the destruction of the tumor with the desired margins and minimal damage to the healthy tissue. In addition to experimental methods, computer modeling has been proven to be an effective approach for improving the performance of microwave ablation (MWA). Moreover, since the thermal spread in biological tissue is difficult to measure, the development of a predictive model from procedural planning to execution may have a great impact on patient care. This study focuses on determining the optimal parameters for MWA treatment of liver tumors using two identical parallel-positioned multi-slot coaxial antennas. The simulation results suggest that an input power of 20 W or 15 W per antenna suffices for complete tumor ablation with a sufficient safety margin for 600 and 900 s, respectively. In both cases, the created ablation zones were similar. The ablation zones for 15 W per antenna were more spherical, invading a smaller amount of healthy tissue than those for 20 W per antenna. This study may represent a step forward in planning MWA treatment for individual patients.

Postnatal neurogenesis appears to be highly sensitive to environmental factors, including microwave electromagnetic radiation (MWR). Here, we investigated the impact of MWR during intrauterine development on juvenile and adult neurogenesis in the rostral migratory stream (RMS) and the dentate gyrus of the hippocampus in the rat brain, as well as its effect on animal behavior. Female rats were exposed to MWR at a frequency of 2.45 GHz for 2 hours daily throughout pregnancy. The offspring of irradiated mothers survived to either juvenile age or adulthood. The brains of the rats were subjected to morphological analysis, assessing cell proliferation and death in both neurogenic regions. In the RMS, the differentiation of nitrergic neurons was also investigated. The effect of MWR on behavior was evaluated in rats surviving to adulthood. Prenatal MWR exposure caused significant changes in the number of proliferating and dying cells, depending on the age of the animals and the observed neurogenic region. In addition, MWR attenuated the maturation of nitrergic neurons in the RMS in both juvenile and adult rats. Morphological alterations in neurogenesis were accompanied by changes in animals’ behavior. Affected neurogenesis and changes in animal behavior suggest a high sensitivity of the developing brain to MWR.

With the rapid advancement and wide application of microwave technology, it enhances convenience while potentially endangering health. The immune system, as a vital shield, is an important protective barrier and also one of the sensitive targets of microwave radiation. The immune system is particularly affected by microwave radiation via innate and adaptive immune responses, which is supported by both population surveys and experimental studies; however, the precise mechanism of immunotoxicity of microwave radiation remains under investigation. In light of recent scientific advances in the correlation between microwave radiation and the immune system, the deleterious impact of microwave radiation on innate immunity was delineated. Microwave radiation can induce irregular innate immune function by damaging macrophages, neutrophils, natural killer cells, and dendritic cells. The effects of microwave radiation on adaptive immunity were also elucidated. Microwave radiation can impair cellular immune response by influencing T cell proliferation, maturation and activation, and distribution of T cell subpopulation, and also hinder humoral immune function by influencing B lymphocyte protein expression, maturation during development, and number of B cells. Disparity in the immune function of the body can precipitate the onset of various immune-associated diseases, so the immunotoxic effects of microwave radiation and associated protection need considerable attention and detailed investigation. This article reviewed the shortcomings of existing studies, and suggested that future experimental studies should use experimental parameters that are more similar to the actual scene of life and work, pay more attention to the biological effects of combined multi-frequency microwave exposure on the immune system, use standardized and unified experimental methods, and incorporate more sophisticated experimental technologies to further elucidate the laws of damage effect and exact mechanism of microwave radiation on the immune system, so as to provide a scientific basis for potent protection against the damage effect of microwave radiation on the immune system.

Sprouts are an attractive food product that contains high amounts of nutritional substances and has pro-health features. Sprout consumption has strongly increased despite its potential risk to health due to its microbial load. Both the safety and shelf life of sprouts may be negatively affected by a high microbial load. To reduce the microbial contamination in sprouts before consumption, the initial microbial load on the seeds needs to be controlled. Many herbal sprouts have been recommended for diabetes, and fenugreek is one of these sprouts. Thus, the current experiment aimed at disinfecting fenugreek seeds using microwave (5, 10, and 20 s) and hot water (30, 45, and 60 s) treatments for different durations. The best-disinfected sprouts with the highest nutritional properties were used to evaluate their influence on streptozocin-induced diabetic rats in comparison with fenugreek seed feeding. Microwave treatments showed the highest sprout length, fresh weight, total free amino acids, antioxidants, reducing sugars, and total phenols. Additionally, microwave seed treatments showed the lowest bacteria and mold counts on sprouts produced relative to hot water treatments, and the best seed treatment was a microwave for 20 s, which gave the best values in this respect. Feeding diabetic rats with different fenugreek seeds or sprout rates (0, 5, 7.5, and 10% w/w) improved body weight, restricted the growth of glucose levels, lowered total cholesterol and triglycerides, and improved HDL compared with the positive control group, and fenugreek sprouts at higher rates showed the maximum improvements in blood glucose, total cholesterol, and triglycerides. Treating fenugreek seed with microwave radiation for 20 s to disinfect the seeds before sprouting is recommended for lowering the microbial load with optimum nutritional and antioxidant activity, and feeding diabetic rats with these sprouts at the rate of 7.5 and 10% had promising effects on hyperglycemia and associated disorders. [ABSTRACT FROM AUTHOR]

The stress–strain diagram of a polymer composite material based on rubber PDI-3A filled with thermally expanded graphite or potassium chloride has been studied before and after microwave treatment for 300, 600, 900, and 1200 s. It has been found that the ultimate tensile strength and strain increase twofold after a 300-s microwave treatment and testing at 223 K. A significant decrease in the stress–strain properties of the synthesized composites with an increase in the test temperature or microwave treatment time is observed. [ABSTRACT FROM AUTHOR]

The present work analyzes the effect of releasing physically bound water from hydrogel, cork, perlite, and ceramsite on materials exposed to microwave radiation and subsequently investigates possible changes in the physical properties of these materials (water absorption and thermal conductivity coefficient). The release of physically bound water from individual materials has potential practical applications in materials engineering, for example, in the internal curing of concrete, where individual aggregates could, under the influence of microwave radiation, release water into the structure of the concrete and thus further cure it. Experimental analysis was carried out with samples of the above-mentioned materials, which were first weighed and then immersed in water for 24 h. Then, they were weighed again and exposed to microwave radiation. After exposure, the samples were weighed again, left immersed in water for 24 h, and weighed again. The focus of the study was on the ability of the aggregates to release water due to microwave radiation and on the changes in the properties (water absorption, thermal conductivity coefficient) of these materials when exposed to microwave radiation. The samples were further monitored by digital microscopy for possible changes in the surface layer of the materials. The hydrogels show the highest water absorption (1000%) and the fastest water release (45 min to complete desiccation). After the release of water due to microwave radiation, their ability to absorb water is maintained. Of interest, however, is that in the case of almost complete removal of water from the soaked hydrogel, the original powdered state of the hydrogel is not obtained, but the outcome has rather a solid structure. In the case of cork, the water absorption depends on the fraction of the material. [ABSTRACT FROM AUTHOR]

Microwave radiation (MWR) has been linked to neurodegeneration by inducing oxidative stress in the hippocampus of brain responsible for learning and memory. Ashwagandha (ASW), a medicinal plant is known to prevent neurodegeneration and promote neuronal health. This study investigated the effects of MWR and ASW on oxidative stress and cholinergic imbalance in the hippocampus of adult male Japanese quail. One control group received no treatment, the second group quails were exposed to MWR at 2 h/day for 30 days, third was administered with ASW root extract orally 100 mg/day/kg body weight and the fourth was exposed to MWR and also treated with ASW. The results showed that MWR increased serum corticosterone levels, disrupted cholinergic balance and induced neuro-inflammation. This neuro-inflammation further led to oxidative stress, as evidenced by decreased activity of antioxidant enzymes SOD, CAT and GSH. MWR also caused a significant decline in the nissil substances in the hippocampus region of brain indicating neurodegeneration through oxidative stress mediated hippocampal apoptosis. ASW, on the other hand, was able to effectively enhance the cholinergic balance and subsequently lower inflammation in hippocampus neurons. This suggests that ASW can protect against the neurodegenerative effects of MWR. ASW also reduced excessive ROS production by increasing the activity of ROS-scavenging enzymes. Additionally, ASW prevented neurodegeneration through decreased expression of caspase-3 and caspase-7 in hippocampus, thus promoting neuronal health. In conclusion, this study showed that MWR induces apoptosis and oxidative stress in the brain, while ASW reduces excessive ROS production, prevents neurodegeneration and promotes neuronal health. [ABSTRACT FROM AUTHOR]

To investigate the dynamic changes in hippocampal metabolism after microwave radiation using liquid chromatography in tandem with mass spectrometry/mass spectrometry (LC–MS/MS) and to identify potential biomarkers. Wistar rats were randomly assigned to a sham group and a microwave radiation group. The rats in the microwave radiation group were exposed to 2.856 GHz for 15 min for three times, with 5 min intervals. The rats in the sham group were not exposed. Transmission electron microscope revealed blurring of the synaptic cleft and postsynaptic dense thickening in hippocampal neurons after microwave radiation. Metabolomic analysis revealed 38, 24, and 39 differentially abundant metabolites at 3, 7, and 14 days after radiation, respectively, and the abundance of 9 metabolites, such as argininosuccinic acid, was continuously decreased. After microwave radiation, the abundance of metabolites such as argininosuccinic acid was successively decreased, indicating that these metabolites could be potential biomarkers for hippocampal tissue injury. [ABSTRACT FROM AUTHOR]

This work highlights using a domestic microwave oven to determine moisture in fish tissues. Also, it compares it with other gravimetric methods established employing a conventional oven (AOAC) and infrared radiation. The optimization of the microwave method was performed utilizing a two-level full factorial design. The AOAC method, which uses a temperature of 105 °C, requires 130 min for the analysis, while the microwave method can be done in 2 min. Intraday and interday tests evaluated the precision of both methods. The determination of the moisture of the fishes Cynoscion acoupa, Argyrosomus regius, Carassius auratus, Sardinella longiceps, Thunnus, Merluccius, Caranx latus, and Brachyplatystoma vaillantii was performed using the microwave and AOAC methods. The analysis of variance and the paired t-test showed no significant differences in the results obtained using these two methods. Also, moisture in other fish tissues was quantified using microwave radiation. [ABSTRACT FROM AUTHOR]

Researches have shown that microwave radiation could cause oxidative stress injury in male reproductive system, and blueberry anthocyanins had excellent oxidation resistance. Our study aimed to investigate the protective effect of blueberry anthocyanins (100, 200 and 400 mg/kg/d) on testicular tissue damage in Wistar rats exposed to 2.856 GHz microwave and the optimal dose. We found that blueberry anthocyanins could ameliorate the decrease of sperm motility and sex hormone levels and testicular tissue structure damage caused by microwave radiation, increase SIRT1 expression and decrease FoxO1 expression, increase GSH/GSSG, SOD and inhibit MDA. The LDH, SDH and ATP synthase were increased, and Caspase-3 expression was decreased, and the high-dose of blueberry anthocyanins (400 mg/kg/d) had the best protective effect. These results suggested that blueberry anthocyanins could inhibit oxidative stress injury induced by 2.856 GHz microwave radiation in rat testicular tissue by regulating SIRT1/FoxO1 pathway, enhance energy metabolism and reduce cell apoptosis.

Some medicinal particles are poorly soluble in highly acidic solutions, particularly those subjected to various production processes. Therefore, the present research investigated the kinetics and mechanisms of the drug release rate of newly formulated solid pills in a low pH medium. Three pills were prepared: one from a non-moisturized powder mixture (PILD) and the other two, PILC and PILM, from the dried powder mixtures, which were dried using hot-air heating and microwave radiation, respectively. These pills were subjected to drug release tests, and the outcomes were considered in the kinetics investigation using various models. Zero-order, Hixson–Crowell, First-order, Higuchi, Hopfenberg, Korsmeyer-Peppas, Logistic, and Peppas-Sahlin were the kinetic models used to inspect the release rate mechanism of these tablets. It was found that the Peppas-Sahlin and zero-order were the most reliable models to represent the drug release profile of all prepared pills with very high accuracy, estimated by R^2>0.99. The Hixon and first-order models were the weakest to characterize this work outcome. This work also applied these models to describe the controlling mechanism of the drug release for each prepared pill. It is detected that the non-Fickian diffusion and polymer chain relaxation control the PILC’s release behavior. However, case II transport and super case II transport with erosions is the dominant mechanism for PILD and PILM pills, respectively. Additionally, new semi-empirical models were modified to describe the kinetics of the solid release of those tablets with greater accuracy.

Objectives. To evaluate the influence and efficiency of using microwave irradiation on the dichlorocarbenation of polar olefins. To determine the conditions (reaction time and process temperature) under which the maximum yield of target gem-dichlorocyclopropanes is achieved.Methods. The target compounds were obtained by classical methods of organic synthesis— acetalization of polyols and dichlorocarbenation of unsaturated compounds. The preparation of gem-dichlorocyclopropanes was carried out using the microwave activation method on a Sineo device (microwave system for organic synthesis, made in China). In order to determine the qualitative and quantitative composition of the reaction masses, gas–liquid chromatography (using the Kristall 2000 hardware complex), mass-spectroscopy (using Chromatek-Kristall 5000M device with NIST 2012), and nuclear magnetic resonance spectroscopy (using Bruker AM-500 device with operating frequencies of 500 and 125 MHz) were carried out.Results. Under microwave irradiation at 25°C for 2 h with the maximum yield (92–98%), the target substituted gem-dichlorocyclopropanes were obtained: 2-(2,2-dichloro-3-methylcyclopropyl)-1,3-dioxolane, 2-(2, 2-dichloro-3-phenylcyclopropyl)-1,3-dioxolane, 8,8-dichloro4-isopropyl-3,5-dioxabicyclooctane, diethyl-2,2-dichloro-3-phenylcyclopropane-1,1-dicarboxylate, and diethyl-2,2-dichloro-3isopropylcyclopropane-1,1-dicarboxylate.Conclusions. Under the conditions herein proposed, the use of the microwave stimulation method in the dichlorocarbenation of double C=C bonds containing polar substituents allows the reduce the temperature and reaction time to be significantly reduced, and the yield of target gem-dichlorocyclopropanes to be increased.

Introduction. The intensive development of technology in the modern world is accompanied by the origin of new types of manmade hazards, one of which is microwave radiation. Despite the considerable range of protective materials, not all of them are suitable for construction purposes. The main obstacle to their use is their high cost, and integrating them into the main types of wall construction materials would require significant changes to their production processes. The most practical and reasonable way to solve the issue is to introduce special additives into concretes and mortars traditionally used for the production of building products. The paper examines the effect of additives of fine-dispersed black carbon and aluminum powder in the composition of cement and gypsum matrices on radio shielding properties in the frequency range 1800–2800 MHz. Materials and methods. Black carbon powder was added to cement and gypsum paste in dosages of 0, 2.5, 5%, aluminum powder was added to gypsum paste in dosages of 0, 2.5, 5%. Superabsorbent polymers pre-saturated with water have been studied. Radio shielding properties have been studied on a designed experimental laboratory installation using a vector circuit analyzer NanoVNA. Results and discussion. The influence of black carbon and aluminum powder additives on the strength and microwave protective properties of gypsum and cement stone is considered. It is found that the addition of black carbon in an amount of up to 3–3.5% of the cement weight shows a neutral effect on the strength of cement stone, providing a decrease in the signal level of about 50% (–6 dB) observed in the ranges 1800–2100 MHz and 2300–2650 MHz, which makes this additive promising for solving the highlighted task. When additives are introduced into the gypsum matrix, the addition of black carbon reduces the radiation level to 60% (–8 dB), and aluminum powder to 69% (–10 dB) in a dosage of no more than 5% of the mass fraction of the binder on samples with a thickness of 3 cm. However, the additives considered have a noticeable negative effect on the strength characteristics of gypsum stone, which allows recommending the use of only black carbon in an amount of no more than 2.5% to obtain products that do not require high strength. Conclusion. The problems of creating construction materials to reduce the level of microwave radiation in the studied frequency range are outlined. Data have been obtained on increasing the shielding ability of cement and gypsum binders with the use of additives

Carbon nanotubes (CNTs) are the strongest candidates as reinforcing and functionalizing materials in civil engineering. However, CNTs have severely limited the application of carbon nanomaterials in civil engineering materials because of high-cost preparation and inhomogeneous dispersion. In this paper, a new method of direct in-situ grown CNTs on the surface of waste glass powder (WGP) by microwave pyrolysis is employed. It can control the particle size and growth of CNTs while effectively improving the CNTs dispersion and saving natural resources. The dispersibility of in-situ grown CNTs and MWCNT in aqueous and cement pore solutions is evaluated based on DLS and improved machine learning and image processing methods. The conductivity as well as the compressive strength of the electrically conductive cementitious materials increases linearly with increasing dispersion. This work facilitates further optimization of CNT-cement nanocomposite dispersion and has great potential for improving WGP utilization efficiency.

An original plasma chemical process initiated by microwave discharge in a mixture of metal and dielectric powders was applied to prepare specific materials, which consisted of microsized spherical particles of aluminum oxide covered with silver nanoparticles. The prepared materials are highly uniform in shape, size distribution, and composition. Their cytotoxicity was investigated using the human cell lines MCF7, HEK293T, A549, and VA-13 and the bacterial strains E. coli JW5503 (ΔtolC) and E. coli K12. Their cytotoxicity was found not to exceed the cytotoxicity of the starting materials. Thus, the prepared materials can be considered highly promising for catalysis and biotechnology applications. [ABSTRACT FROM AUTHOR]

The brain is complex and metabolically active, and the detection of metabolites plays an important role in brain development and diseases. Currently, there is a lack of research on the metabolic spectrum changes in learning and memory impairment, and hippocampal damage induced by microwave radiation from the metabolic perspective. Aiming to provide sensitive indicators for microwave radiation-induced brain damage and establish a foundation for understanding its injury mechanisms, this study employed non-targeted metabolomics to investigate metabolic fluctuations and key metabolic pathway alterations in rats' hippocampal tissue after microwave radiation. The memory and spatial exploration abilities of rats decreased after radiation. The postsynaptic densities were thickened in the MW group. The cholesterol sulfate, SM(d16:1/24:1(15Z)), and linoelaidylcarnitine were significantly increased after radiation, whereas etrahydrocorticosterone, L-phenylalanine, and histamine were significantly decreased after radiation. These metabolites were enriched in signaling pathways related to the inflammatory mediator regulation of transient receptor potential (TRP) channels, neuroactive ligand–receptor interaction, steroid hormone biosynthesis, and phenylalanine, tyrosine, and tryptophan biosynthesis. These findings indicate that microwave radiation causes spatial learning and memory dysfunction in rats and structural damage to hippocampal tissue. [ABSTRACT FROM AUTHOR]

Purpose: Among the various applications involving the use of microwave energy, its growing utility within the mining industry is particularly noteworthy. Conventional grinding processes are often overburdened by energy inefficiencies that are directly related to machine wear, pollution and rising project costs. In this work, we numerically investigate the effects of microwave pretreatment through a series of compression tests as a means to help mitigate these energy inefficiencies. Design/methodology/approach: We investigate the effects of microwave pretreatment on various rock samples, as quantified by uniaxial compression tests. In particular, we assign sample heterogeneity based on a Gaussian statistical distribution and invoke a damage model for elemental tensile and compressive stresses based on the maximum tensile stress and the Mohr–Coulomb theories, respectively. We further couple the electromagnetic, thermal and solid displacement relations using finite element modeling. Findings: (1) Increased power intensity during microwave pretreatment results in decreased axial compressive stress. (2) Leveraging statistics to induce variable compressive and tensile strength can greatly facilitate sample heterogeneity and prove necessary for damage modeling. (3) There exists a nonlinear trend to the reduction in smax with increasing power levels, implying an optimum energy output efficiency to create the maximum degradation-power cost relationship. Originality/value: Previous research in this area has been largely limited to two-dimensional thermo-electric models. The onset of high-performance computing has allowed for the development of high-fidelity, three-dimensional models with coupled equations for electromagnetics, heat transfer and solid mechanics. [ABSTRACT FROM AUTHOR]

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The antioxidant properties of selenium nanoparticles coated with arabinogalactan have been studied. The nanoparticles were characterized by transmission electron microscopy and infrared spectroscopy. Arabinogalactan-coated selenium nanoparticles were incubated together with Ehrlich ascitic carcinoma cells and then exposed to microwave radiation. The antioxidant properties of selenium nanoparticles were evaluated using chemiluminescent analysis. The viability of Ehrlich ascitic carcinoma cells under microwave irradiation and incubation with selenium nanoparticles was assessed by flow cytometry. Under conditions of exposure to experimental tumor cells of microwave radiation, the concentration of free radicals in the cells did not change. The effect of arabinogalactan-coated selenium nanoparticles on tumor cells is expressed as an increase in the delay time for the activation of the antioxidant system. [ABSTRACT FROM AUTHOR]

Extractive oxidation of diesel via microwave processing using sulfuric acid and two synthesized pyridinium- or methylpyridinium-based ionic liquids has been studied as a sustainable and clean technology. The Central Composite Design (CCD) representing one of the response surface methods was applied for the experimental design, mathematical modeling, optimization, and factor-influence study, which covered the 0.75–1.75 [CH2COOHmPy][HSO4]/[H2SO4] volumetric range, 40–80°C temperature range, and 120–300 s radiation exposure time. The developed model properly fitted experimental results, with a coefficient of determination (R2) equal to 0.9832 that indicated its accuracy. The highest predicted sulfur removal (93.338%) as well as a significant removal of nitrogen and aromatic compounds was obtained for [CH2COOHmPy][HSO4]/[H2SO4] = 1.57, T = 71.7°C, and exposure time equal to 208 s. Microwave-assisted extractive oxidation demonstrated a considerable potential as the energy-saving technology, which meets the future need for producing clean fuels with low content of heteroatoms and polyaromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

The influence of microwave radiation on the vulcanizate of a polyurethane binder based on PDI-3B low-molecular rubber has been studied. The densities of the thermal energy of microwave radiation absorbed by the material have been calculated. It has been shown that an increase in the density of thermal energy absorbed by the sample leads to a significant increase in the deformability of the material, which is associated with a change in the density of the spatial network. [ABSTRACT FROM AUTHOR]

At the intersection of insect control and sustainability goals, dielectric heating emerges as a promising solution. In agriculture, where insect pests can reduce agricultural yields and the nutritional quality of crops under field and storage conditions. Chemical pesticides are often used to manage pests but owing to their deleterious consequences on humans and the environment, chemical-free treatments have become the preferred option. Among the existing options, applying radio frequency (RF) and microwave energy for the purpose of dielectric heating has proven to be a successful alternative to chemical pesticides for controlling some major insect pests. This review offers an overview of dielectric heating for pest control in both storage settings and field environments, which addresses pests that impact materials with varying moisture contents (MC). The review highlights the limitation of this technology in controlling insect pests within bulk materials, leading to non-uniform heating. Additionally, it discusses the application of this technology in managing pests affecting materials with high MC, which can result in the degradation of the host material's quality. The review suggests the combination of different techniques proven effective in enhancing heating uniformity, as well as leveraging the non-thermal effects of this technology to maintain the quality of the host material. This is the first review providing an overview of the challenges associated with employing this technology against high moisture content (MC) materials, making it more advantageous for controlling storage pests. Overall, the review indicates that research should particularly emphasize the utilization of this sustainable technology against insect pests that inflict damage on high (MC) substances.

When earthquakes occur in high-mountain areas during the winter season, the epicentral region is often covered by a snow layer, which can be either thin or thick. The presence of snow and/or ice layers affects the detection of thermal anomalies associated with seismic signals. Taking into account the penetration capabilities of microwaves, microwave brightness temperature data were analyzed by using the index of microwave radiation anomaly to study the response of the epicentral region associated with two recent strong earthquakes in Central Asia, which occurred in snow-covered mountainous areas. Increased microwave radiation was observed within one week prior to the earthquakes. By conducting a comparative analysis of different frequencies and a comprehensive examination of meteorological parameters, we distinguished anomalies caused by tectonic activity from those induced by atmospheric water vapor. A robustness analysis from the periods of seismic tranquility and seismic disturbance has been conducted to validate our results. Our findings suggest that regions with less snow cover or shallow snow depth may exhibit high sensitivity to seismic microwave radiation anomalies in high-altitude mountainous areas during the cold season, which can be detected through passive microwave remote sensing. Combined with a further analysis from microwave polarization difference index and distribution of regional lithology, we proposed that the theory of positive holes may be the dominant mechanism for enhanced microwave radiation.

Abstract As a recognized special resource, tar-rich coal can extract the country's scarce oil and gas resources and generate semi-coke that can replace anthracite and coking coal. The tar-rich coal in northern Shaanxi is prominent, but due to the dense structure and high strength of tar-rich coal, it is easy to cause frequent dynamic disasters in coal mining. Therefore, the realization of pressure relief and disaster reduction has become the primary problem in mining tar-rich coal. There are many shortcomings in conventional pressure relief methods, so a new method of microwave-weakening coal is proposed. Through different water saturation treatments of tar-rich coal samples, the longitudinal wave velocity degradation trend and surface crack expansion law of water-bearing coal after microwave irradiation were analyzed, and the strength softening characterization and energy evolution relationship under the combined action of microwave and water were studied. Fractal dimension and its internal correlation based on the equivalent side length-mass of coal sample fragments. The experimental results show that: (1) Under the same microwave radiation condition, with the increase of water saturation, the deterioration trend of physical and mechanical parameters such as longitudinal wave velocity and peak strength is obvious. (2) After microwave radiation, the uniaxial compression results show that the coal sample is damaged by load, there is still a high residual strength, the ratio of elastic energy to dissipation energy decreases, and the possibility of rockburst of the coal sample decreases. The strength softening degree of coal specimen under the degradation of microwave and water is the highest, followed by microwave and water. (3) The fractal dimension is inversely proportional to the moisture content and microwave radiation intensity, and the fractal dimension has a significant positive correlation with the peak intensity and longitudinal wave velocity. The mechanical damage law of water-bearing tar-rich coal under microwave action is revealed, which aims to solve the problem of weakening and reducing the impact of hard coal on-site to a certain extent, ensure the safety of working face, and improve the mining efficiency of tar-rich coal. It provides basic theoretical support for microwave-assisted hydraulic fracturing technology and effective weakening measures for hard roof treatment.

In this study, microwave radiation pulses emitted from natural lightning have been found to interfere with the Fourth Generation Long Term Evolution (4G LTE) mobile communication data transmission. Two sets of measurement instruments have been synchronized where lightning electric field sensor together with 4G LTE network were evaluated its performance under two conditions namely fair-weather (four cases) and storm (four lightning cases). The microwave radiation emitted from lightning was directly measured without the use of a mixer and down-convertor to ensure the preservation of information such as the number of pulses and amplitude. A client-server architecture has been set up for data transmission utilizing User Datagram Protocol (UDP) where the packets have been generated by using Internet Performance Working Group Third Version (Iperf3) platform. Under fair-weather conditions, the 4G LTE connection at both the client and server nodes demonstrated stability and experienced minimal impact. On the other hand, natural lightning electromagnetic interference disrupted the 4G LTE communication links. Among the four reported storms, three storms have affected the 4G LTE data transmission. The first and fourth storms resulted in a complete connection drop to zero, lasting for 4 minutes and 2 seconds and for 44 seconds, respectively. The observation of hundreds microwave radiation pulses, each characterized by individual oscillating features suggests a potential disruption to packet transmission. Moreover, negative could-to-ground (-CG) and intra-cloud (IC) lightning flashes have been identified as the primary sources of interference to the 4G LTE data transmission. This information could be useful for future studies and for developers working on improving the reliability and performance of 4G LTE networks, particularly in areas prone to thunderstorms.

The method of fabrication of solid solution powder of uranium/plutonium (38%) oxides from the pulp of ammonium uranyl-plutonyl carbonate process (AUPuC) by microwave radiation in reducing and atmospheric environments was proposed and tested at the laboratory level. For research the pulp was prepared, obtained by co-precipitation of uranium and plutonium from nitrate solution (simulator for stripping product). The process consists of three main stages: oxidation of Pu(IV) to Pu(VI), precipitation, and conversion in a laboratory microwave unit. According to data of the X-ray diffraction analysis the powders synthesized in a reducing atmosphere and an atmospheric environment are a solid cubic solution (UxPu1–x)O2 and (PuO2, U3O8) mixed oxide, respectively. Scanning electron microscopy and electron probe microanalysis of the powder obtained in an atmospheric environment showed a fairly uniform distribution of U, Pu, and O in the solid phase. [ABSTRACT FROM AUTHOR]

The work is aimed at the development of an energy-saving technique involving the partial carboxylation of powdered lignocellulose products from the straw of annual agricultural plants and the use of the obtained products in rubber compositions as a water-swelling filler. Lignocellulose powder from oat straw (composition: α-cellulose—77.0%, lignin—3.8%, resins and fats—1.8%) was used for carboxylation without preliminary separation into components. Microwave radiation was used to activate the carboxylation process. This reduced the reaction time by 2–3 times. The synthesized products were analyzed by IR spectroscopy, thermogravimetry and scanning electron microscopy. Industrial product sodium carboxymethylcellulose (Na-CMC) was used as a swelling filler for comparison. The swelling fillers were fractionated by the sieve method; particles with the size of 0–1 mm were used for filling rubber compounds. The amount of swelling filler was 150 parts per 100 parts of rubber (phr). Due to the high filling of rubber compounds, plasticizer Oxal T-92 was added to the composition of a number of samples to facilitate the processing and uniform distribution of ingredients. The rubber composition was prepared in two stages. In the first stage, ingredients without swelling filler were mixed with rubber on a laboratory two-roll mill to create a base rubber compound (BRC). In the second stage, the BRC was mixed with the swelling filler in a closed laboratory plasti-corder rubber mixer, the Brabender Plasti-Corder® Lab-Station. Vulcanization was carried out at 160 °C. For the obtained samples, the physical-mechanical and sorption properties were determined. It has been shown that the carboxylated powdered lignocellulose from oat straw increases the strength properties of rubber in comparison with Na-CMC. It has been shown that when the carboxylated powdered lignocellulose from oat straw is introduced into the rubber composition, the degree of rubber swelling in aqueous solutions of various mineralizations increases by 50 and 100% in comparison with a noncarboxylated lignocellulose. [ABSTRACT FROM AUTHOR]

Microwave radiation in the production of lightweight aggregates, it has not yet been thoroughly explored. Therefore, the main goal of the research is to analyze the possibility of using various types of waste, such as waste rock (0–30 %) and glass cullet (10 %), fly ash (50–80 %) and waste solution using different microwave temperature (1000, 1050, 1100 °C) in order to obtain lightweight aggregates. Above factors and, chemical and mineral composition of the waste materials, affect the microstructure and physico-mechanical parameters of the aggregates.). The thermophysical behavior (DTG/TG), grain composition, chemical composition (XRF), phase composition (XRD) and microstructure (SEM, μ-CT) were analyzed. The microstructure, as well as the related characteristics of aggregates, i.e. water absorption, density, and compressive strength, depend on the sintering temperature, chemical composition and mineral waste raw material. The best properties were obtained for a raw material mixture containing 80 % coal fly ash, 10 % glass cullet, 10 % clay and 48 g of the waste solution (per 100 g of raw mixture), sintered in the microwave at 1100 °C. The aggregates were characterized by water absorption of 6.96 %, bulk of 1.70 g/cm3, loose bulk density 0.60 g/cm3, and compressive strength 5.95 MPa. Closed porosity determined by micro-CT was 8.41 %, open - 0.24 %, sphericity 0.62. The total porosity depends on the loose bulk density and particle density of lightweight aggregates. Furthermore, washout tests meet environmental requirements. The proposed technology, moreover, enables a short time of thermal processing of raw materials, and thus energy savings and a sustainable approach to the production of green pellets. Thanks to the high strength, the obtained aggregates can replace commercial aggregates. Flow chart for the manufacture of the artificial aggregates. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: Attention provides the foundation for cognitions, which was shown to be affected by microwave (MW) radiation. With the ubiquitous of microwaves, public concerns regarding the impact of MW radiation on attention has hence been increased. Our study aims to investigate the potential effect and mechanism of acute microwave exposure on attention. Results: We identified obvious impairment of attention in mice by the five-choice serial reaction time (5-CSRT) task. Proteomic analysis of the cerebrospinal fluid (CSF) revealed neuroinflammation and microglial activation potentially due to acute MW exposure. Moreover, biochemical analysis further confirmed microglial activation in the prefrontal cortex (PFC) of mice subjected to acute MW exposure. Finally, minocycline, a commercially available anti-inflammatory compound, attenuated neuroinflammation, inhibited the upregulation of N-methyl-D-aspartic acid receptor (NMDAR) including NR2A and NR2B, and also accelerated the attentional recovery after MW exposure. Conclusions: We believe that microglial activation and NMDAR upregulation likely contribute to inattention induced by acute MW exposure, and we found that minocycline may be effective in preventing such process. [ABSTRACT FROM AUTHOR]

A series of theoretical and experimental studies was carried out with the aim of a direct comparison of the thermal and microwave destruction of peat during pyrolysis. Different heating mechanisms in these processes were investigated in the framework of simulations conducted using a commercial 3D software package, CST Studio Suite, to define their specific features. Based on these simulations, identical reactors were constructed exploiting an electric element and a microwave complex as a heat source, and an experimental technique was developed that allows these processes to be correctly compared under similar conditions. Using these reactors based on different heat sources, comparative experiments on peat pyrolysis were performed, and the results of the theoretical analysis were confirmed. As a result, the advantages of microwave exposure were demonstrated to achieve a more uniform and deep fragmentation of peat, increase the reaction rate and reduce the processing time, with high energy efficiency accompanying this method. As part of the experiments, the yield of pyrolysis products was analyzed. During the microwave destruction of peat, a high gas output (up to 27%) was obtained, which allows for a further increase in the efficiency of this processing method when burning these gases. The conducted elemental analysis showed an increase in the percentage of carbon from about 50% to 78% after microwave processing, which can become a raw material for obtaining effective environmentally friendly sorbents. The prospects for creating industrial microwave complexes for processing organic materials are discussed. [ABSTRACT FROM AUTHOR]

In this paper, an algorithm for restoring the precipitation intensity over the ocean surface according to data from the MTVZA-GYa Russian microwave sounder is presented. The developed algorithm is based on the ALG'85 regression model in which the precipitation intensity is estimated using the scattering index on a high-frequency radiometric channel (~90 GHz). In this work, the scattering index is simulated based on MTVZA-GYa data and compared with GPM IMERG reanalysis data. To restore the precipitation intensity, it is proposed to use a fourth-degree polynomial. The quantitative estimates show that the RMS spread reaches 50%, and the correlation coefficient does not exceed 0.75. The qualitative comparison indicates a significant difference between the restored rain rate and the GPM IMERG data, as well as the presence of a shift of the precipitation area. As a result of the analysis, it is concluded that the incorrect convergence of the beams of the radiation patterns for different frequency channels of the MTVZA-GYa device might be one of the causes. [ABSTRACT FROM AUTHOR]

The possibilities of igniting a combustible mixture in a high-speed flow using a microwave streamer discharge are considered. The results of experimental studies of the streamer discharge structure at various pressures are presented. To quantitatively characterize the intensity of combustion of fuel ignited by a microwave discharge, pressure and temperature measurements are used in various sections of the jet in the discharge wake. The results obtained demonstrate the possibility of igniting a model combustible mixture when propane or its mixture with air is sup-plied to the discharge region. The main physical mechanisms responsible for heating the discharge plasma to the ignition temperature of the combustible mixture and their characteristic time scales are revealed. The change in the dimensions of the combustion zone with a decrease in the initial proportion of propane in the mixture is discussed. The minimum duration and minimum level of microwave radiation required to ignite a model combustible mixture under various conditions are determined. [ABSTRACT FROM AUTHOR]

The adsorption activity of a carbon material based on lignin modified with iron salts and carbonized under the influence of microwave radiation in relation to 2,4-dichlorophenoxyacetic acid (2,4-D) from an aqueous medium was studied. The kinetic parameters of the adsorption process were determined. Based on the results obtained, the possibility of using the test material as an adsorbent of biologically active organic compounds was shown. [ABSTRACT FROM AUTHOR]

Using the method of a coaxial capacitor at the frequencies of 10 and 100 kHz, the dielectric permittivity of 200VNP NiZn ferrite and 1SCH32 nickel ferrite spinel rings is measured. These rings are used in nonlinear transmission lines to sharpen the front of high-voltage pulses and to generate nanosecond microwave pulses. [ABSTRACT FROM AUTHOR]

Ignition of combustible air/propane mixture in a high-speed flow with a microwave streamer discharge is considered. The experimental results of structure of streamer discharge and quantities at various pressures are presented. Pressure and temperature measurements in various sections of the streamer discharge in high-speed flow are analysed. The results obtained demonstrate the possibility of ignition of air/propane combustible mixture. The main physical mechanisms responsible for heating the discharge plasma to the ignition temperature of the combustible mixture and their characteristic time scales are discussed. The minimum time and minimum level of microwave radiation required to ignite a combustible mixture under various conditions are determined. • Streamer discharge structure at various pressures in high-speed flow is presented. • Streamer discharge provides reliable ignition in a high-speed flow. • Minimum time and pulse energy required to ignite a mixture are determined. [ABSTRACT FROM AUTHOR]