Effect Of Microwave Irradiation Research Articles

Experimental Investigation on the Effects of Microwave Irradiation in Pore Structures of LN2 Freezing Coal for Coalbed Methane Extraction

Experimental Investigation on the Effects of Microwave Irradiation in Pore Structures of LN2 Freezing Coal for Coalbed Methane Extraction

Comparison of microwave and conventional pyrolysis of one-step prepared metal soaps (Li/Na/K/Ca/Mg): Product distribution and heating characteristics

The pyrolysis of metal soaps to produce hydrocarbon rich fuel has been studied extensively. However, the combined effects of microwave radiation and metal ion types on hydrocarbon production have not been addressed. In this study, the microwave and conventional pyrolysis experiments were conducted on five metal soaps (Li soap, Na soap, K soap, Ca soap, Mg soap). The results demonstrated that the metal ions at the carboxyl end of the soap enhanced the polarity of the reactants, leading to a rapid increase in temperature under microwave conditions. With the ion radius increasing, the heating rate increased gradually. Compared with conventional pyrolysis, microwave pyrolysis exhibited a more rapid heating rate, a higher degree of carbon chain fracture, and a greater abundance of small olefin compounds, which promoted aromatization reaction and the release of CO, H2 and CH4. In addition, the composition of the pyrolysis products derived from different metal soaps is affected by the characteristics of metal ions. As the radius of metal ions increased, the oxygen content in the liquid products decreased gradually, while the carbon content increased. The strengthening effect of microwave was further analyzed. With the increase in the radius of metal ions, the strengthening effect of microwaves on olefins formation was gradually weakened, while the inhibiting effect on alkanes formation was gradually enhanced. The structure of carboxylate network is affected by the radius of metal ions, which results in the regular change of the strengthening effect of microwave on olefins and other products. This study is highly significant in guiding the pyrolysis of soapstock waste to prepare olefins and alkanes with high efficiency and low energy consumption.

The Comminution of Chert Gravel by Microwave Irradiation

Chert, a by-product rock of sand quarrying, has historically posed economic challenges for aggregate production, resulting in significant “waste” accumulation in quarries. Our study investigates the effect of microwave irradiation on the mechanical properties of chert gravel, a mineralogically homogenous material composed of fine quartz grains. The results, which demonstrate that increased irradiation time leads to a substantial decrease in chert gravel strength (by a factor of 4–6 for 2.5 min of irradiation), underscore the potential impact of this research on comminution processes. With quenching altering the fractional content of the samples after the crushing test, reducing the Gravel-to-Sand ratio, this study is driven by the promising potential of crushed chert gravel as a pivotal aggregate within the concrete and asphalt industries, offering a practical solution to their material needs. The urgent need to rehabilitate previously utilized quarry areas, offering an environmentally beneficial solution for which we all should be responsible, motivated the present study.

Effect of low microwave temperature on the physical and chemical properties of waste activated sludge

In this study, the effect of microwave (MW) irradiation at a target temperature of 80 °C with a heating rate of two °C/min and a holding time of five minutes on the physicochemical properties of activated sludge was studied. The results showed that subjecting biosludge to MW pretreatment resulted in a reduction in particle size to 14.5, 44.6, and 72.8 for d10, d50, and d90, respectively and an increase in the specific surface area of the biosludge to 235.9 m<sup>2</sup>/kg. Pretreatment resulted in an increase in soluble oxygen demand, sugar, and protein concentrations to 2,380.0 mg/L, 66.5 mg/L, and 1.81 g/L, respectively. A slight increase in the release of inorganic compounds, especially NH<sub>4</sub>-N and PO<sub>4</sub>-P, was observed in the disintegrated biosludge. While there was an increase in release of K and Zn, a decrease in concentrations of Na, Ca, Mg, and Al in the liquid was observed after MW irradiation. It was determined that the dewatering property deteriorated after biosludge disintegration, as it increased from raw sludge to disintegrated sludge by 21-fold.

Anomalously Large Heat Generation of Hydration Water under Microwave Irradiation.

Much attention has been paid to the biological effects of microwave irradiation. The hydration water surrounding a biomolecule is crucial in its biological reactions and functions. Therefore, it is important to know the response of hydration water to microwaves to understand their biological effects; however, the scarcity of studies about it often leads to speculations and debates about that effect. In this study, we have made real-time temperature measurements of reverse micellar solutions with their water droplet size from ∼2.3 to ∼9.5 nm using a waveguide system combined with a microwave generator at 2.45 GHz. The heat generated by water in reverse micelles has been observed to depend on their size. It is about 10 times larger than that of liquid water at their small sizes (<∼3.5 nm) and diminishes with further enlarging the size, approaching the water's value at their large sizes (∼10 nm). These results indicate that the heat generation behavior has an interfacial effect; specifically, the hydration water on the surfactant layer produces heat 10 times larger than bulk water. Moreover, the hydration number per surfactant molecule decreases in a core-shell model with increasing the reverse micelle size. These features are also reflected in the heat generation rate. Our findings may offer a new and fundamental perspective for studies on the biological effects of microwave irradiation.

Improving technology for disinfecting grain from pests of bread stock using ultra-high radiation frequencies

The article is devoted to the study of baking properties of flour made from microwave disinfected grain. The article also discusses methods that can assess the quality and safety of grain products. Measures taken for disinfestation of grain storage facilities are complex, expensive and require a complete shutdown of production, so it is relevant to search for new approaches to disinfestation of grain storage facilities without complete suspension of the work process. In this regard, methods of grain disinfestation using microwave radiation, electric fields and other physical methods that do not require stopping production are of considerable interest. The results of studies have shown that the use of microwave irradiation with high-frequency electromagnetic fields significantly increases the efficiency of destruction of pests in grain. The analysis of the effect of microwave irradiation on moisture, gluten content and temperature of grain indicates that the use of electromagnetic fields with a power of 180 W for 120-160 seconds does not affect the physical and chemical characteristics of grain. According to organoleptic evaluations, at optimal treatment parameters (180 W/m2 for 120-160 seconds) the color, aroma and taste of grain remain unchanged.

Microwave catalytic pyrolysis of heavy oil: A lump kinetic study approach

Managing heavy oil (HO) has become a vital issue in terms of environmental considerations. Microwave pyrolysis of HO is one of the efficient methods of upgrading and recycling this complex material. In this work, microwave catalytic pyrolysis (MCP) of HO was explored by investigating the effect of heating time (2–10 minutes) and temperature (460–730ºC) on the product yield and quality. The most critical point of this study was utilizing a unique design of SiC foam@HZSM-5 as a microwave absorber and catalyst simultaneously. This special design could eliminate the main problem of previous studies: the unwanted temperature gradient inside the reactor, which was misleading the prediction of kinetic parameters by recording the wrong temperature. The yield of each product’s category from the MCP process was reconstructed through a biharmonic spline interpolation (BSI) algorithm to visualize the simultaneous effect of the heating time and temperature on the yield. The optimum temperature for the MCP process was about 600ºC and a heating time of 6 minutes, which yielded the most valuable hydrocarbons in liquid and gas products. The produced liquid oil and non-condensable gases were analyzed through GC-MS and the collected results were categorized based on the properties of the detected compounds. An eight-lump kinetic model was then proposed based on that categorization. The calculated pre-exponential factors (k0) were higher than the expected values, while the apparent activation energies (Ea) were considerably lower than the reported data in the literature, which was due to the non-thermal and thermal effects of microwave irradiation on the reaction mechanism. The validation of the proposed model indicated the capability of this model to predict reliable data under these conditions.

Ashwagandha Diminishes Hippocampal Apoptosis Induced by Microwave Radiation by Acetylcholinesterase Dependent Neuro-Inflammatory Pathway in Male Coturnix coturnix Japonica.

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 2h/day for 30days, third was administered with ASW root extract orally 100mg/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.

Microwave irradiation of guar seed flour: Effect on anti-nutritional factors, phytochemicals, in vitro protein digestibility, thermo-pasting, structural, and functional attributes.

Guar seed flour (GSF) has a high amount of carbohydrates, proteins, phytochemicals, and anti-nutritional factors (ANFs), which limits its use. To address this issue, the current study was undertaken to understand the effect of microwave (MW) irradiation on ANFs, phytochemicals, in vitro protein digestibility (IVPD), and functional attributes of GSF at varying power density (Pd: 1-3W/g) and duration (3-9min). The ANFs were determined using a colorimetric assay and a Fourier transform infrared spectrum. At 3Pd-9min, the maximum reduction in ANFs (tannin, phytic acid, saponin, and trypsin inhibitor activity) was observed. Higher Pd and treatment duration increased antioxidant activity and total phenolic content, except for total flavonoid content. Furthermore, compared to the control sample (78.38%), the IVPD of the GSF samples increased to 3.28% (3Pd-9min). An increase in Pd and duration of MW treatment improved the thermal and pasting properties of GSF samples up to 2Pd-9min. Due to inter- and intramolecular hydrogen bonding degradation, the relative crystallinity of the 3Pd-9min treated GSF sample was 30.58%, which was lower than that of the control (40.08%). In MW-treated samples, SEM images revealed smaller clusters with rough and porous structures. However, no noticeable color (ΔE) changes were observed in MW-treated samples. Aside from water absorption capacity and water solubility index, MW treatment reduced oil absorption capacity, foaming capacity, and emulsifying capacity. As demonstrated by principal component analysis, MW irradiation with moderate Pd (2-3) was more effective in reducing ANFs, retaining nutritional contents, and improving the digestible properties of GSF, which could be a potential ingredient for developing gluten-free products.

Effects of microwave radiation on the physicochemical properties, structure, and digestibility of the synthesized different crystal forms of malic acid starch ester

The effects of microwave combined with L-malic acid treatment on the degree of substitution (DS), structure, physicochemical properties, and digestibility of sweet potato starch (A-type), potato starch (B-type), and pea starch (C-type) were evaluated. The order of DS obtained was: DSM-POS > DSM-SPS > DSM-PES. Fourier transform-infrared spectroscopy (FT-IR) showed that the obtained modified starch produced a new absorption band at 1735 cm−1. Scanning electron microscopy (SEM) and polarized light microscopy indicated that different types of native starches exhibited different granular morphologies and appeared to have different degrees of damage, but still had polarized crosses after modification. Sweet potato starch had the smallest particle size, while potato starch had the largest. X-ray diffractometry (XRD) showed that the modified starches still retained the same crystal structure as the native starches, but the relative crystallinity decreased. The apparent viscosity and swelling power of modified starches dropped, but their water/oil holding capacity, amylose content, and resistant starch content all increased. The results demonstrate that the degree of influence on the structure, physicochemical properties, and digestibility of different starches varies under the same modification conditions.

Radiation-driven diffusive transport of fast electrons in solar flares

Fast electron scattering on plasma ions due to stimulated Bremsstrahlung is investigated and modeled. Comparison with Coulomb scattering suggests that stimulated Bremsstrahlung scattering can be dominant in low-density, radiation-driven plasmas, provided that the radiation spectrum has a sufficiently high brightness temperature in the neighborhood of the plasma frequency. While stimulated Bremsstrahlung scattering cannot be easily observed in laboratory plasmas due to their small size, it should operate in large-scale astrophysical plasmas, such as those met in the flaring solar corona. The effect of the solar microwave radiation on fast-electron scattering is evaluated through a parameterized flaring corona model. We find that stimulated Bremsstrahlung greatly enhances the fast-electron scattering frequency in the flare magnetic loop, leading the transport of deka-keV electrons to occur in the diffusion regime, characterized by significant precipitation rates. This prediction is consistent with the interpretation of the above-loop-top hard x-ray and microwave emissions from the X3.1 flare of August 24, 2002. Our analysis indicates that stimulated Bremsstrahlung may play an essential role in the dynamics of fast electrons trapped in solar flare loops.

Microwave Treatment of Three Different Types of Sewage Sludge Based on Their Solar Drying Exposure Time: Effect on Microorganisms, Water Content and Agronomic Aspects

This study aimed to treat sewage sludge through microwave irradiation at a laboratory scale. The objective was to investigate the effect of microwave irradiation on microorganisms, water content, organic matter, and agronomic nutrients present in sewage sludge. Three types of sewage sludges obtained from a full-scale wastewater treatment plant were considered: Sludge A (raw sludge), Sludge B (subjected to 15 days of solar exposure, achieving 48% dryness), and Sludge C (exposed to solar conditions and left open to the air for 23 months, reaching 94% dryness). These diverse sludges were exposed to microwave irradiation at various power levels (analysed variables: ε (Watts/g), θ (°C), T (min)). The specific exposure powers and temperature levels for the water reduction analysis were: 555, 955, 1355, and 1500 Watts/g and 55, 75, 95, and 105 °C, respectively. On the other hand, microbiological and agronomic nutrient analyses were conducted at 75 °C–1355 W and 95 °C–1355 W. After microwave exposure experiments, the results demonstrated the high effectiveness of microwave technology in eradicating indicator microorganisms of faecal contamination and reducing sludge volume while not affecting trace elements of significant agricultural value. The reduction in Escherichia Coli revealed that 4 min of irradiation was necessary to completely eliminate it to 0 ulog, indicating a 100% reduction, in Sludge A. In Sludges B and C, an additional 1 min was needed under conditions of 75 °C and 1355 W for a mass of 50 g. Moreover, Sludge A (46.27 × 105 or 4.80 ulog of dry matter), Sludge B (1.29 × 106 or 6.11 ulog of dry matter), and Sludge C (8.77 × 104 or 4.94 ulog of dry matter) were heavily contaminated with faecal coliforms. It took 6 min to reduce faecal coliforms to below the detection threshold.

Stability and enhanced low-temperature NH3-SCR activity of supported vanadate catalysts in a microwave field

The promoting effect of microwave irradiation on the NH3-SCR activity of the NdV/Ti-x% catalysts and their stability in the microwave field.

The Law and Mechanism of the Effect of Surface Roughness on Microwave-Assisted Rock Breaking

In physical engineering, a rock surface, whether naturally or artificially formed, is rough. When irradiating rocks, microwaves produce reflections and diffractions on the surface of rough rocks, which significantly affect the absorption of microwave energy by rocks, thus influencing the result of microwave irradiation. In order to explore the influence of rough rock surfaces on the effect of microwave-assisted rock breaking, microwave irradiation tests were carried out on basalt samples with different values of roughness to test the temperature and P-wave velocity of the samples before and after microwave irradiation. Numerical test methods were used to systematically study the influence of rough rock surfaces on microwave irradiation. The results show that, under the same microwave irradiation conditions, the effect of microwave irradiation on rough surface basalt is more significant than that of flat surface basalt. The surface temperature distribution range of flat surface specimens is narrow, the surface temperature range of rough surface specimens is wider and more inhomogeneous, and the maximum surface temperatures of rough surface specimens are much higher than those of flat surface specimens. After irradiation, new macroscopic cracks were generated on the surface of the samples, and the crack propagation of the rough surface samples was more obvious. The decrease in P-wave velocity before and after the irradiation of flat surface samples is small, and that of rough surface samples is larger. The main factors affecting the effect of microwave irradiation on the rough surface are the refraction and reflection of electromagnetic waves, heat conduction, and stress concentration on the surface.

Effect of Microwave Irradiation on Coloring and Mechanical Properties of Direct Dyed Fabric

Microwaves have a very short wavelength which allows them to pass through the small spaces between molecules without being scattered. This allows the microwaves to penetrate the matter and heat it from the inside out, providing uniform heat, and makes microwave technology ideal for applications that require rapid and consistent heating. It has been hypothesized that microwaves may have a positive effect on the shade depth and color fastness of the fabric due to the increased temperature. This research is being done to test this hypothesis and to study the effects of microwaves on the shade depth and color fastness properties of the fabric. Microwave-irradiated fabric dyed before and after dyeing has a greater shade depth and better fastness properties than fabric dyed without irradiation.

Fluidization‐bed drying and microwave radiation effects on drying rate, fatty acid, protein, and germination of flaxseed

AbstractFlaxseeds are known for their invaluable omega‐3 fatty acids and proteins. Flaxseeds need to be dried to 10%w.b. moisture for safe long‐term storability. Traditional drying ruptures the nutritional properties, therefore, this study analyzed the effect of fluidized‐bed and microwave drying on the fatty acid and protein constituency of flaxseed. The drying air temperatures in the fluidized‐bed drying tests were 40, 50 and 60°C. Three microwave power densities were selected 0.3, 0.6 and 1 W g−1. Results showed a minor effect on fatty acids whereas a significant effect on protein content with both the drying methods. A protein reduction of 7, 21, and 23% was observed for drying air temperatures of 40, 50, and 60°C, respectively. For the microwave tests, 39, 58, and 63% protein reductions for 0.3, 0.6 and 1 W g−1 power densities were observed, respectively. The fatty acids showed a maximum increase of 0.85% for fluidized bed drying and 1.23% for microwave.Practical applicationsThis study contributes a step‐forward knowledge toward adoption of microwave technology in flaxseed oil extraction industry. Previous pilot‐scale studies solely on microwave utilization have shown limited scale‐up due to its high infrastructure cost associated with emitting high‐power densities. However, if explored with a combination approach along with fluidized bed (40°C at 0.3 W g−1) to assist in early removal of surface moisture from flaxseed, it could be a potential platform to increase the productivity in parallel to matching the associated overall cost. A proper cost analysis could be a future aspect of this study.

Microwave assisted synthesis, spectroscopy, crystal structure, characterization and Hirshfeld surface analysis of ureidopeptides and intermediates derived from α,α-dipeptides C-terminal glycine

This article describes synthetically useful catabolic pathway activation of the primordial peptide cycle through the effect of microwave irradiation, giving a new variety of peptide derivatives: the α,α-ureidopeptides, as 1,3-disubstituted unsymmetrical ureas via hydantoin, starting from NCbz protected α,α-dipeptide methyl esters containing glycine as the C-terminal residue. The new ureidopeptide series were synthesized and structurally characterized by FT-IR, MS, 1H NMR, 13C NMR spectroscopy, and single-crystal X-ray diffraction analysis. Molecular structure and crystal packing of Phe-Gly-ureidopeptide 3h noted C12H14N2O5, in a monoclinic system and C2/c space group with parameters a = 32.42 Å, b = 9.62 Å, c = 8.40 Å, β=103.25°, and Z = 8, Z’=1, confirm assignations evaluated for the new compounds. The procedure has been extended to the isolation of the α,α-ureidopeptide intermediate, the hydantoin Leu-Gly 4e, C9H14N2O4, demonstrating the synthetic mechanism and crystallized in an orthorhombic system, Pbca space group, with parameters a = 5.19 Å, b = 11.49 Å, c = 35.99 Å, α=β=γ=90°, and Z = 8, Z’=2. Hirshfeld surface analysis on crystal structures of both ureic-derivatives revealed crystal packing relevance and stabilization by the competition of predominant supramolecular interactions easily discernible as nonconventional intermolecular CH•••π, and classical NH•••O or C = OOH•••O = COH, forming complex hydrogen bonding patterns.

Effect of Microwave Irradiation on staining methods of Connective Tissue Fibers (collagen Fiber)

Effect of Microwave Irradiation on staining methods of Connective Tissue Fibers (collagen Fiber)

Evaluation of the Effect of Microwave Irradiation and Die Hardener Application on Surface Hardness of Type IV Dental Stone

Type IV dental stone play an important role during fabrication of indirect dental restoration. It should be accurate in every respect, dimensionally stable over time, hard enough to with stand fabrication process resistant to the inadvertent abrasions caused by fabrication. The aim of present study was to evaluate the effect of microwave irradiation and die hardener application on surface hardness of type IV dental stone. Two commercial brands of type IV dental stone (Spofadental/ Czech, Zhermack/ Italy) were evaluated. 30 samples were prepared from each brand and left to dry for 24hr. After that divided into three groups, control group (10 samples withou t treatment), 10 samples subjected to microwave irradiatio n at 650 watt output power and 2450 MHZ for 10 mint. And 10 samples painted with die hardener. Surface hardness measured with Shore C (Durometer, Digital hardness tester). The die hardener application not affect surface hardness of both brands (P&gt;0.05). However microwave irradiation increase surface hardness of Spofadental Type IV dental stone. But reduce surface hardness of Z hermack Type IV dental stone. After 24hr. of pouring Type IV dental stone (Spofadental / Czech, Zhermack / Italy) die hardener application not affect surface hardness. However surface ha rdness of Spofadental Type IV dental stone may be improved with microwave irradiation. But Zhermack Type IV dental stone s howed reduction in surface hardness after microwave irradiati on.

Analytical investigation of asphaltene cracking due to microwave and ultrasonic radiations: A molecular insight into asphaltene characterization and rheology

Asphaltene is a fraction of crude oil that causes technical and environmental problems because of its instability and precipitation. Microwave and ultrasonic radiations have been proven to be efficient for oil viscosity reduction and removal of asphaltene precipitants. This research aims to investigate the alteration of the asphaltene molecular structure from a molecular point of view, as well as their rheological behavior, due to microwave and ultrasonic radiations. Nuclear Magnetic Resonance (NMR), Fourier Transformed Infrared (FTIR), Energy Dispersive X-ray (EDX) spectroscopies, and Elemental analysis were implemented to find the ultrasonic and microwave radiation effects on the molecular structure of two asphaltene samples. Based on the obtained results, the number of fused aromatic rings is reduced due to ultrasonic and microwave radiations, indicating aromatic core cracking. The number of aliphatic carbons is reduced, representing the aliphatic chain cracking. Besides, the increase in the aliphatic chain length, aside from aromatic core cracking, was a sign of the ring opening. The reduction of the polar groups, such as carbonyl, in the microwave-treated asphaltene, was explained by more vulnerability of materials with higher dielectric constants to the microwave. The ultrasonic radiation was more feasible for removing heavier elements, such as oxygen. The aggregation behavior of the untreated/treated asphaltenes was investigated through rheological tests. The viscosity of the oil sample bearing treated asphaltene was lower than the ones bearing crude asphaltene, representing reducing the ability for aggregation. Based on the structural parameters and chemistry of the treated asphaltenes, weakening of hydrogen bonding interaction and π- π stacking were recommended mechanisms for reducing asphaltene aggregation and oil viscosity. This research could be used to modify the asphaltene structure to hinder the technical and environmental issues, caused by the asphaltene precipitations.