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Biomass pyrolysis is the most effective process to convert abundant organic matter into value-added products that could be an alternative to depleting fossil fuels. A comprehensive understanding of the biomass pyrolysis is essential in designing the experiments. However, pyrolysis is a complex process dependent on multiple feedstock characteristics, such as biomass consisting of volatile matter, moisture content, fixed carbon, and ash content, all of which can influence yield formation. On top of that, product composition can also be affected by the particle size, shape, susceptors used, and pre-treatment conditions of the feedstock. Compared to conventional pyrolysis, microwave-assisted pyrolysis (MAP) is a novel thermochemical process that improves internal heat transfer. MAP experiments complicate the operation due to additional governing factors (i.e. operating parameters) such as heating rate, temperature, and microwave power. In most instances, a single parameter or the interaction of parameters, i.e. the influence of other parameter integration, plays a crucial role in pyrolysis. Although various studies on a few operating parameters or feedstock characteristics have been discussed in the literature, a comprehensive review still needs to be provided. Consequently, this review paper deconstructed biomass and its sources, including microwave-assisted pyrolysis, and discussed the impact of operating parameters and biomass properties on pyrolysis products. This paper addresses the challenge of handling multivariate problems in MAP and delivers solutions by application of the machine learning technique to minimise experimental effort. Techno-economic analysis of the biomass pyrolysis process and suggestions for future research are also discussed. [ABSTRACT FROM AUTHOR]

Oil fuels derived from fossils are non-renewable, so over time, they will run out and have a negative impact on air pollution. To overcome this, there is a need for environmentally friendly alternative fuels from renewable sources such as biodiesel. This research used microwave heating with a CaO catalyst. NaOH-impregnated snail shells and active carbon support. This research aims to determine the effect of power on the conversion of candlenut seed oil into biodiesel using the NaOH/CaO/CA catalyst both in terms of compliance with the SNI 7182-2015 standard and analysis using GC-MS (Gas Chromatography-Mass Spectrometry). The synthesis of the NaOH/CaO/CA catalyst was carried out through wet impregnation and calcination at a temperature of 500°C and analyzed using gas sorption analysis (GSA). Then proceed to the transesterification process, where the power for microwave heating was varied to 300, 450, and 600 watts with a mole ratio of esterified oil and methanol, namely 1:10 for 3 minutes. The analysis results of the NaOH/CaO/CA catalyst using the GSA instrument have a surface area of 9.306 m2/g, pore volume of 0.033 cc/g, and pore diameter of 14.043 nm. Meanwhile, the results of the biodiesel analysis showed that the optimum biodiesel yield was 85.625% at 600 watts of power and had a kinematic density and viscosity that met the SNI 7182-2015 biodiesel standards. Analysis of biodiesel characteristics using GC-MS showed that the three most optimum biodiesel components were hexadecanoic acid, methyl ester (22.664%), 9,12-Octadedecadienoic acid (Z,Z)-, methyl ester (30.176%) and 9-Octadecenoic acid (Z)-, methyl ester (38.656%).

Oil fuels derived from fossils are non-renewable, so over time, they will run out and have a negative impact on air pollution. To overcome this, there is a need for environmentally friendly alternative fuels from renewable sources such as biodiesel. This research used microwave heating with a CaO catalyst. NaOHimpregnated snail shells and active carbon support. This research aims to determine the effect of power on the conversion of candlenut seed oil into biodiesel using the NaOH/CaO/CA catalyst both in terms of compliance with the SNI 7182-2015 standard and analysis using GC-MS (Gas Chromatography-Mass Spectrometry). The synthesis of the NaOH/CaO/CA catalyst was carried out through wet impregnation and calcination at a temperature of 500°C and analyzed using gas sorption analysis (GSA). Then proceed to the transesterification process, where the power for microwave heating was varied to 300, 450, and 600 watts with a mole ratio of esterified oil and methanol, namely 1:10 for 3 minutes. The analysis results of the NaOH/CaO/CA catalyst using the GSA instrument have a surface area of 9.306 m2/g, pore volume of 0.033 cc/g, and pore diameter of 14.043 nm. Meanwhile, the results of the biodiesel analysis showed that the optimum biodiesel yield was 85.625% at 600 watts of power and had a kinematic density and viscosity that met the SNI 7182-2015 biodiesel standards. Analysis of biodiesel characteristics using GC-MS showed that the three most optimum biodiesel components were hexadecanoic acid, methyl ester (22.664%), 9,12-Octadedecadienoic acid (Z,Z)-, methyl ester (30.176%) and 9-Octadecenoic acid (Z)-, methyl ester (38.656%). [ABSTRACT FROM AUTHOR]

In the world of industrial drying processes, foam mat microwave drying is a significant and valuable approach. Its advantages include increased drying effectiveness, preservation of product quality, energy and cost savings, flexibility in application, and improved safety. Development of Nagpur mandarin juice powder is tedious and time-consuming due to its bitter test and less total soluble solid, therefore the present research carried out with the process parameters for microwave drying include microwave power levels (180, 360, 540, 720, and 900 W) and drying bed thicknesses (2, 4, and 6 mm). Foamed juice is produced using soy protein isolate (2.10 %), GMS (2.75 %), CMC (1.75 %), and sugar (5.10 %), with whipping times of 8 min. Additional foaming agents include guar gum (0.45 %), soy protein isolate (3.30 %), and sugar (10 %) with whipping times of 6 min. The optimal conditions for drying Nagpur mandarin juice were determined through analysis using Design-Expert 11.0.4.1 software. These conditions include 540 W of microwave power, a drying bed thickness of 3 mm, and the use of a foaming agent comprising 2.10 % soy protein isolate, 2.75 % GMS, 1.75 % CMC, and 5.10 % sugar, with an 8-min whipping period. Under these optimized conditions, the resulting powder exhibited the following characteristics: color b value of 19.59, ΔE (change in color) of 6.24, acidity of 0.40 %, ascorbic acid content of 36.64 mg/100 g, water activity of 0.26, drying time (in minutes), and overall acceptability rating of 7.77. These findings highlight the effectiveness of the optimized process parameters in achieving desirable quality attributes for Nagpur mandarin juice powder production.

This study investigates the optimization of microwave-assisted extraction (MAE) condition for phenolic antioxidants from Gossampinus malabarica flowers by response surface methodology (RSM) using a central composite design (CCD). The best combinations of microwave power (MP), solid to liquid (S-L) ratio, ethanol concentration and time were identified through MAE using RSM from G. malabarica flowers. The manipulation of process variables significantly influenced the extraction of bioactive compounds (BCs), with the MP and S-L ratio demonstrating high significance in the extraction of BCs. The optimized extraction conditions consisted of an MP of 1,000 W, a S-L ratio of 1:100, an ethanol concentration of 20 % (w/v), and an extraction time of 20 s, resulting in the highest extraction yield, extractable phenolic compounds, DPPH antioxidant activity and total flavonoid content. The actual experimental results are closely associated with the predicted values, affirming the efficacy of RSM in optimizing the phenolic extraction process from G. malabarica flowers.

This article explores the optimization of microwave-assisted extraction (MAE) technology for the extraction of turmeric oil. The study used response surface methodology (RSM) to analyze the effects of process variables on the oil yield and quality. The results indicated that hexane was a more effective solvent compared to petroleum ether, and the optimal conditions for extraction were a microwave power of 300 watts and an extraction time of 20 minutes. The study concludes that MAE is a safe, efficient, and economically feasible method for turmeric oil extraction, with potential applications in various industries and medical science. [Extracted from the article]

Microwave-assisted freeze drying (MFD) is particularly suited for drying heat-sensitive materials. However, optimizing process parameters is time-consuming due to lengthy individual experiments. This study investigates the feasibility of partial MFD for parameter studies, with the process being terminated after removing 20 wt% of the water contained. The proposed approach reduces the time required for parameter evaluation by 92.0% compared to complete MFD. It also enables the evaluation of the samples' drying homogeneity. A subsequent parameter study based on partial MFD was then conducted to evaluate the effects of chamber pressure, microwave power, and microwave frequencies on the drying kinetics and drying homogeneity. Lowering the average chamber pressure from 0.87 mbar to 0.19 mbar reduced the process duration by 18.8%. An increase in the dissipated specific microwave power from 0.048 W/g to 0.143 W/g reduced the duration by 46.7%. The targeted application of frequencies increased the average energy efficiency to as high as 92.4%, contributing to a shortened process duration of up to 51.2%. Only the application of multiple frequencies caused a notable increase in drying homogeneity. In summary, this study demonstrates the feasibility and time-saving benefits of partial drying for parameter studies in MFD and potentially different types of drying processes. [ABSTRACT FROM AUTHOR]

The aim of this study is to use the response surface methodology (RSM) to mathematically model the response parameters and emission of greenhouse gases (GHG) and optimize the drying variables for a carrot dried with the microwave method using various pretreatments. To this end, the influence of the drying parameters (independent), such as microwave power and slice thickness dried by two pretreatments of ultrasonication at 30 °C for 10 min and blanching at 70 ℃ for 2 min, was explored on the dependent (response) parameters including the thermal properties (drying time, effective moisture diffusion coefficient (Deff), specific energy consumption, energy efficiency, quality features (color changes and shrinkage), and GHG emission (including CO2 and NOx). It should be mentioned that the emission of GHG was determined based on the energy consumption of various types of power plants such as the gas turbine steam power turbine, and combined cycle turbines using various fuels such as natural gas, heavy oil, and gas oil. The results indicated that the ultrasonication and blanching pretreatments can decrement the drying time (linearly), energy consumption (linearly or quadratically), shrinkage(quadratically), and color changes(quadratically) and enhance the Deff (linearly) and energy efficiency (linearly or quadratically) in all samples with R2 > 0.86. Moreover, the shortest drying time (42 min), lowest SEC (9.51 MJ/kg), and GHG emission ((4279.74 g CO2 in the combined cycle turbines plant, and 18.16 g NOX in the gas turbine plant) with natural gas for both plants) were recorded for the samples pretreated with blanching while the lowest color changes (13.69) and shrinkage (21.29) were observed in the ultrasonicated samples. Based on the optimization results, a microwave power of 300 W and steam power turbine of 2 mm were the best variables with a desirability of about 80% which resulted in the highest-quality products at the lowest GHG emission. [ABSTRACT FROM AUTHOR]

Biomass is a promising resource for the production of renewable energy, liquid fuels, and chemicals. Microwave pyrolysis is one of the directions of multifunctional conversion of raw materials. In the present work, the effect of microwave power on the characteristics of sawdust pyrolysis is studied. With an increase in power, the maximum yield of combustible gases increased, and a large proportion of the total pyrolysis time included the useful time for the release of gases. An increase in power affected the yield of individual gases non-linearly and on a different scale. The average yield of CO and CO2 remained practically unchanged when the microwave power was increased from 840 to 1760 W. However, with a further increase in power to 2200 W, there was a significant increase in the average yield of CO and CO2 (2.5 and 1.4 times, respectively). An increase in power by 2.6 times contributed to an increase in the average yield of CH4 by 5 times and H2 by 3.8 times. The increased power of microwaves contributed to the degassing of wood and intensification of secondary pyrolysis reactions, which resulted in a decrease in the mass of the solid residue by 5.3 times and a decrease in the liquid product yield by 2.7 times. A comprehensive analysis using MCDA showed that an increase in energy costs with an increase in microwave power is integrally compensated by an improvement in pyrolysis performance. So, when the power was varied from 840 W to 2200 W, the pyrolysis efficiency indicator increased by 1.3–2.2 times, considering the growth in energy consumption. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to bring the bone broth-based sauce into powder form by microwave assisted hot air drying method and to determine the drying characteristics of this product. Bone broth-based sauces were dried at the drying temperatures of 60, 70 and 80 °C, and at the microwave powers of 90, 180 and 360 W, until a moisture content of 10% (dry basis). The moisture ratio (MR) was significantly influenced by the drying temperature and microwave power. Ten kinetic models were selected to evaluate MR data, with regard to adjusted regression coefficient (R2), the reduced chi-square (χ2) and root mean square error (RMSE). Midilli and Page models exhibited a better fit for the drying kinetics of bone broth-based sauce than the other drying models tested. In addition, the effective moisture diffusivity (Deff) and activation energy (Ea) values were 1.27 × 10−7 m2/s and 27 kJ/mol, respectively. Consequently, these results can be used to simulate the microwave assisted hot air drying of bone broth-based sauce and improve the efficiency of the drying process. [ABSTRACT FROM AUTHOR]

The study investigated the effects of different microwave vacuum freeze-drying powers (100–500 W) on the emulsifying properties and structural characteristics of egg white protein, which is of great significance in enhancing the added value of EWP and promoting its application. Emulsification analysis revealed that the emulsification performance was significantly influenced by microwave power and reached its maximum at 300 W. Fourier-transform infrared spectroscopy (FT-IR) and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) analyses showed that microwave vacuum freeze-drying treatment altered the secondary structure of EWP without changing its peptide structure. Fluorescence measurements indicated that the maximum fluorescence emission intensity decreased, and the maximum emission wavelength shifted towards blue as the power increased. Particle size, zeta potential, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses showed that the average particle size of EWP reached the minimum value of 1203.66 nm, the absolute value of zeta potential reached the maximum value of 41.35 mV, and the thermal stability was strongest, with a more uniform and loose structure observed at 300 W. Texture profile analysis (TPA) showed that appropriate power treatment significantly enhanced the chewiness and viscoelasticity of egg white protein. Therefore, appropriate power treatment could effectively improve the emulsifying properties and stability. [ABSTRACT FROM AUTHOR]

Discovery of the capacity of microwave energy to heat materials was a major milestone in the history of technology and scientific research. This discovery led to the development of many devices and processes that have replaced conventional heating methods, thereby reducing reliance on fossil fuels and reducing atmospheric CO 2 emissions. Over the past two decades the use of microwave heating for processing of non-dielectric metals, metal powders alloys have increased markedly and includes sintering, melting, joining, cladding, drilling, and 3D printing. These developments have used a wide range of experimental procedures, and the use of microwave power has resulted in significant benefits over conventional heating methods. These benefits include a many-fold decreases in processing times and energy consumption, as well as improved microstructural characteristics and mechanical properties of the processed material. This review provides a comprehensive overview of the state-of-the-art of microwave processing of metals, metal powders and their alloys and focuses on important process parameters such as heating mechanisms, electromagnetic properties of metals, the factors affecting these parameters and applications to metal processing. Requirements for efficient metal processing using microwave power are presented including metal properties, microwave susceptors, insulators, ceramic containment structures and temperature measurement methods that all play roles in the development of microwave processing of metals and metal alloy materials. Current challenges and issues in equipment design parameters and various processing methods to facilitate commercial implementation of metal processing at larger scales are investigated. [Display omitted] • Microwave heating: a sustainable approach for processing metallic materials. • Understanding microwave heating and the factors influencing metal processing. • Evolution and growth of the microwave processing applications of metals. • Proposal of forty pairings of NW-MWSC with molten metals for MW processing tools. • Challenges and opportunities in microwave metal processing. [ABSTRACT FROM AUTHOR]

Power sensor nonlinearity contributes significantly to the increase of the microwave power measurement uncertainty. Current methods for sensor calibration do not provide correction of the results, due to the sensor nonlinearity. The paper describes an improved method and an automated measuring system based on it for power sensor calibration that enables the correction of the results, taking into account amplitude and frequency dependent nonlinearity. The novel calibration method is based on the application of high-linearity thermistor power transfer standard. The power sensor calibration process is fully automated and improved by applying the automated measuring system, PC and VEEpro software. Performed calculation of the calibration measurement uncertainty and the analysis of power measurement uncertainty budget indicate that the new calibration method allows the correction of sensor nonlinearity and contributes to significant reduction of the microwave power measurement uncertainty, ranging from 15,8% to 40,5%. Experimental results and validation confirm the applicability of the improved calibration method and prove the existence of significant dependence of sensor nonlinearity on the power level, but also on the frequency of the measured microwave power.

Basic aluminum sulfate desorption desulfurization, as a renewable desulfurizer and rich in high-purity SO2, had attracted extensive attention at home and abroad. In order to enhance the desorption performance, the effects of microwave power and desulfurization rich liquid flow on desorption performance were studied under the microwave dynamic desorption system. The results show that the dynamic desorption system operated stably and has good desorption effect under the continuous action of microwave. The desulfurization rich liquid can be stably maintained at the target desorption temperature in the desorption bottle, while a lower temperature level can be obtained in the desorption buffer bottle to eliminate the influence of thermal desorption. Under certain desulfurization rich liquid flow and microwave power, high microwave power and desulfurization rich liquid flow could significantly promote the desorption performance. The desorption ratio at the desorption end point reaches more than 72. 26% and 71. 64% and the desorption rate reaches more than 1. 874 5 × 10 - 4 mol / (L·min) and 2. 443 5 × 10 - 4 mol / (L·min). Under high microwave power, the heating rate, desorption ratio, and desorption rate are significantly improved, and the non-thermal effect of microwave desorption is more prominent. High desulfurization rich liquid flow increases the circulation ratio and prolongs the effective action time of microwave, which is beneficial to the improvement of desorption ratio and desorption rate. [ABSTRACT FROM AUTHOR]

The aim of this study is to use the response surface methodology (RSM) to mathematically model the response parameters and emission of greenhouse gases (GHG) and optimize the drying variables for a carrot dried with the microwave method using various pretreatments. To this end, the influence of the drying parameters (independent), such as microwave power and slice thickness dried by two pretreatments of ultrasonication at 30 °C for 10 min and blanching at 70 ℃ for 2 min, was explored on the dependent (response) parameters including the thermal properties (drying time, effective moisture diffusion coefficient (Deff), specific energy consumption, energy efficiency, quality features (color changes and shrinkage), and GHG emission (including CO2 and NOx). It should be mentioned that the emission of GHG was determined based on the energy consumption of various types of power plants such as the gas turbine steam power turbine, and combined cycle turbines using various fuels such as natural gas, heavy oil, and gas oil. The results indicated that the ultrasonication and blanching pretreatments can decrement the drying time (linearly), energy consumption (linearly or quadratically), shrinkage(quadratically), and color changes(quadratically) and enhance the Deff (linearly) and energy efficiency (linearly or quadratically) in all samples with R2 > 0.86. Moreover, the shortest drying time (42 min), lowest SEC (9.51 MJ/kg), and GHG emission ((4279.74 g CO2 in the combined cycle turbines plant, and 18.16 g NOX in the gas turbine plant) with natural gas for both plants) were recorded for the samples pretreated with blanching while the lowest color changes (13.69) and shrinkage (21.29) were observed in the ultrasonicated samples. Based on the optimization results, a microwave power of 300 W and steam power turbine of 2 mm were the best variables with a desirability of about 80% which resulted in the highest-quality products at the lowest GHG emission.

Biomass is a promising resource for the production of renewable energy, liquid fuels, and chemicals. Microwave pyrolysis is one of the directions of multifunctional conversion of raw materials. In the present work, the effect of microwave power on the characteristics of sawdust pyrolysis is studied. With an increase in power, the maximum yield of combustible gases increased, and a large proportion of the total pyrolysis time included the useful time for the release of gases. An increase in power affected the yield of individual gases non-linearly and on a different scale. The average yield of CO and CO2 remained practically unchanged when the microwave power was increased from 840 to 1760 W. However, with a further increase in power to 2200 W, there was a significant increase in the average yield of CO and CO2 (2.5 and 1.4 times, respectively). An increase in power by 2.6 times contributed to an increase in the average yield of CH4 by 5 times and H2 by 3.8 times. The increased power of microwaves contributed to the degassing of wood and intensification of secondary pyrolysis reactions, which resulted in a decrease in the mass of the solid residue by 5.3 times and a decrease in the liquid product yield by 2.7 times. A comprehensive analysis using MCDA showed that an increase in energy costs with an increase in microwave power is integrally compensated by an improvement in pyrolysis performance. So, when the power was varied from 840 W to 2200 W, the pyrolysis efficiency indicator increased by 1.3–2.2 times, considering the growth in energy consumption.

Microwave curing technology has been widely used in resin and its composite materials. In order to study its effect for curing unsaturated polyester resin (UPR) composites containing calcium carbonate (CaCO3) filler, this paper first investigated the influence of microwave power and microwave irradiation time on the curing characteristics of UPR. Then, CaCO3 particles were added to the UPR to investigate the microwave curing effect of the UPR composites containing the CaCO3. The results showed that microwave irradiation could heat the UPR sample evenly, and rapidly cause the chain growth reaction, thus greatly shortening the curing time. The curing degree and products of the samples after microwave curing were consistent with that of the thermal curing. The addition of CaCO3 particles could increase the heating rate of the UPR composites, which would accelerate the curing rate of the UPR. However, higher microwave power could lead to pore defects inside the UPR composites with higher CaCO3 content, resulting in a lower strength. Thus, the compactness of the samples should be improved by reducing the microwave power and prolonging the microwave treatment time. [ABSTRACT FROM AUTHOR]

The optimum hole diameter of a ring reflector was experimentally investigated using an axial virtual cathode oscillator (vircator) to enhance its microwave power. The ring reflector enhances the microwave power from the axial vircator by forming a cavity. The ring reflector was installed 9 mm behind the anode. The optimum hole diameter of the ring reflector was analyzed through simulations and experiments by changing the diameter from 60 mm to 160. PIC simulations show that the maximum peak microwave power was generated when the hole diameter was 116 mm and enhanced by 210%. The experiments show similar results to the simulations. The largest peak maximum power was 23.67 MW when the hole diameter was 120 mm. The simulations show that the dominant microwave frequency was formed between 5.33 GHz and 6.7 GHz. The experiments show that the dominant microwave frequency was formed between 5.3 GHz and 5.8 GHz. The frequency trend was approximately similar to that of the simulation results. However, the trend depending on the hole diameter was not as obvious as in the simulations. Although the frequency change was not as clear as in the simulations, experiments show that the hole diameter of the ring reflector affects the vircator operation. [ABSTRACT FROM AUTHOR]

The study investigated the effects of different microwave vacuum freeze-drying powers (100–500 W) on the emulsifying properties and structural characteristics of egg white protein, which is of great significance in enhancing the added value of EWP and promoting its application. Emulsification analysis revealed that the emulsification performance was significantly influenced by microwave power and reached its maximum at 300 W. Fourier-transform infrared spectroscopy (FT-IR) and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) analyses showed that microwave vacuum freeze-drying treatment altered the secondary structure of EWP without changing its peptide structure. Fluorescence measurements indicated that the maximum fluorescence emission intensity decreased, and the maximum emission wavelength shifted towards blue as the power increased. Particle size, zeta potential, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses showed that the average particle size of EWP reached the minimum value of 1203.66 nm, the absolute value of zeta potential reached the maximum value of 41.35 mV, and the thermal stability was strongest, with a more uniform and loose structure observed at 300 W. Texture profile analysis (TPA) showed that appropriate power treatment significantly enhanced the chewiness and viscoelasticity of egg white protein. Therefore, appropriate power treatment could effectively improve the emulsifying properties and stability.

High-quality diamond prepared by microwave plasma chemical vapor deposition (MPCVD) has application prospects in many high-precision fields. The film deposition experiments were carried out using microwave power 9 kW. The chamber pressures are 13 kPa, 14 kPa, 15. 5 kPa, and 17 kPa, respectively. It was found that the deposited films under pressure of 15. 5 kPa and 17 kPa exhibit abnormal growth in the central region, which is manifested as an obvious stepped bulge in the center. Surface morphology and film quality of the film were analyzed by SEM and Raman in order to reveal the reason for the abnormal deposition in the center of the film. Meanwhile, the deposition process was modeled, the power density and flow field distribution were calculated and analyzed by numerical simulation. The results show that at the same power, increasing the chamber pressure and compressing the plasma will lead to more dense growth in the central region of the film than that in the edge region and obvious steps in the central region of the diamond film, due to the short mean free path and insufficient diffusion capacity. The overall growth rate, uniformity and quality of the film will decrease after exceeding pressure limit. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In contrast to conventional casting, casting using in situ microwave route is an advanced and promising technique of bulk metal casting wherein bulk metal is heated and melted in microwave radiations at 2.45 GHz. In this present work, AA-6063 is used as a charge material at three microwave powers of 600 W, 750 W and 900 W. The process uses three susceptor materials—stone charcoal, wood charcoal and SiC—and solidification is done at two levels as closed and open cavity. The optimization of the process parameters has been done through Taguchi technique. Microstructure and microindentation hardness studies of the developed casts divulged that smaller equiaxed grains could be obtained in densely cast samples 15 and 9. In these cast samples, the presence of intermetallic phases of Al2Mg3, MgZn2, Mg2Si, Al2Mg was observed; however, the cast sample 18 contains intermetallic phases of Al2Mg, MgZn and Al2Mg3. It was found from this work that the grain structure and intermetallic precipitates in the developed cast depend primarily on solidification environment, microwave power and susceptors. Microindentation hardness of the cast sample 18 in the present study was about 166 HV that is higher than the other developed casts. The characterization of developed casts in terms of microstructure, elemental analysis, porosity, XRD and fractography is analyzed. The results reveal that the rapid solidification and increased microwave power alter elemental composition, distribution and size of eutectic phases resulting in increase in the microindentation hardness. [ABSTRACT FROM AUTHOR]

Bu çalışmada, baharatlanmış hindi dilimleri farklı sıcaklıklarda (60 ve 70°C) ve mikrodalga güçlerinde (sabit ürün ağırlığında 0, 180 ve 360 W) kurutulmuş ve bu kurutulmuş dilimlerin fiziksel, kimyasal, mikrobiyolojik ve duyusal kalite karakteristikleri belirlenmiştir. Bu koşullarda kurutulmuş hindi dilimlerinin ortalama nem içeriği %25, aw değeri 0.72, pH değeri 6.02 ve tiyobarbitürik asit reaktif maddeleri (TBARS) değeri 15.77 µmol MDA/kg idi. Örneklerin kesilme kuvveti değerinin, sıcaklık artışına bağlı olarak 56.14 N'ye, mikrodalga gücündeki artışa bağlı olarak 59.12 N'ye yükseldiği tespit edilmiştir. Ayrıca, mikrodalga gücü arttıkça örneklerin L* değerinin önemli düzeyde (p < 0.01) azaldığı bulunmuştur. Buna ilaveten, mikrobiyal kalite 70°C kurutma sıcaklığı ve 360 W mikrodalga gücü uygulanan örneklerde daha iyi olmuştur. [ABSTRACT FROM AUTHOR]

The aim of present work was mainly to study the influence of blanching-freezing pre-treatment on moisture removal characteristics of potato during microwave drying process. The influence of microwave power and the samples thickness was also assessed. For this purpose, microwave powers of 100, 350 and 550 W were practiced to dry discoid shape samples of fresh and blanched-frozen potatoes with a constant diameter of 20 mm and different thicknesses of 5, 10 and 15 mm. The obtained results revealed that time required to dehydrate treated potatoes was significantly (P < 0.05) shorter than the fresh ones. The moisture diffusivity of the fresh and blanched-frozen potatoes was determined to be in the range of 9.13 × 10−9‒7.93 × 10−8 and 9.89 × 10−9‒9.36 × 10−8 m2 s−1, respectively where enhanced with the both increasing power level and samples thickness. The average energy required to instigate water diffusion inside the treated samples with 5, 10 and 15 mm thickness was obtained to be 0.463, 0.379 and 0.331 W g−1, respectively while the values for fresh samples were 0.505, 0.466 and 0.413 W g−1, respectively. [ABSTRACT FROM AUTHOR]

Bi-metallic nanoparticles (NPs) have appeared to be more efficient as antimicrobials than mono-metallic NPs. The fungus Aspergillus terreus-mediated synthesis of bi-metallic Ag-Cu NPs was optimized using response surface methodology (RSM) to reach the maximum yield of NPs. The optimal conditions were validated using ANOVA. The optimal conditions were 1.5 mM total metal (Ag + Cu) concentration, 1.25 mg fungal biomass, 350 W microwave power, and 15 min reaction time. The structure and shape of the synthesized NPs (mostly 20–30 nm) were characterized using several analytical tools. The biological activities of the synthesized NPs were assessed by studying their antioxidant, antibacterial, and cytotoxic activity in different NP concentrations. A dose-dependent response was observed in each test. Bi-metallic Ag-Cu NPs inhibited three clinically relevant human pathogens: Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa. Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus were inhibited less. The DPPH and hydrogen peroxide scavenging activities of the NPs were high, reaching 90% scavenging. Ag-Cu NPs could be studied as antimicrobials in different applications. The optimization procedure using statistical analyses was successful in improving the yield of nanoparticles. [ABSTRACT FROM AUTHOR]

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To reduce thermal processing hazards (TPHs), microwave baking has been extensively used in food thermal processing. In this study, the influence of microwave power and microwave time on the formation of TPHs and their precursors was explored in microwave-baked biscuits. The results indicated that the content of acrylamide, 5-hydroxymethylfurfural, methylglyoxal, and 3-deoxyglucosone increased linearly with the extension of microwave time (2, 2.5, and 3 min) and microwave power (440, 480, and 520 W). There was a significant correlation between the four TPHs. 3-Deoxyglucosone may directly or indirectly participate in the formation of the other three TPHs. The relationship between TPH levels with some heat-induced sensory characteristics was analyzed. The correlation between the sensory characteristics and the content of TPHs is L* > a* > hardness > Water activity (AW). The correlation coefficients between L* value and the four TPHs are −0.950, −0.891, −0.803, and −0.985. Furthermore, the content of TPHs produced by traditional baking and microwave baking under the same texture level was compared. Compared with traditional baking (190°C, 7 min), microwave baking at 440 W for 3 min successfully decrease methylglyoxal, 3-Deoxyglucosone, acrylamide, and 5-hydroxymethylfurfural content by 60.75, 30.19, 30.87, and 61.28%, respectively. Traditionally baked biscuits, which had a more obvious color, as characterized by lower L* value, larger a* and b* values, are more susceptible to the formation of TPHs. Therefore, microwave baking can reduce the generation of TPHs.

Microwave curing technology has been widely used in resin and its composite materials. In order to study its effect for curing unsaturated polyester resin (UPR) composites containing calcium carbonate (CaCO3) filler, this paper first investigated the influence of microwave power and microwave irradiation time on the curing characteristics of UPR. Then, CaCO3 particles were added to the UPR to investigate the microwave curing effect of the UPR composites containing the CaCO3. The results showed that microwave irradiation could heat the UPR sample evenly, and rapidly cause the chain growth reaction, thus greatly shortening the curing time. The curing degree and products of the samples after microwave curing were consistent with that of the thermal curing. The addition of CaCO3 particles could increase the heating rate of the UPR composites, which would accelerate the curing rate of the UPR. However, higher microwave power could lead to pore defects inside the UPR composites with higher CaCO3 content, resulting in a lower strength. Thus, the compactness of the samples should be improved by reducing the microwave power and prolonging the microwave treatment time.

In the world of industrial drying processes, foam mat microwave drying is a significant and valuable approach. Its advantages include increased drying effectiveness, preservation of product quality, energy and cost savings, flexibility in application, and improved safety. Development of Nagpur mandarin juice powder is tedious and time-consuming due to its bitter test and less total soluble solid, therefore the present research carried out with the process parameters for microwave drying include microwave power levels (180, 360, 540, 720, and 900 W) and drying bed thicknesses (2, 4, and 6 mm). Foamed juice is produced using soy protein isolate (2.10 %), GMS (2.75 %), CMC (1.75 %), and sugar (5.10 %), with whipping times of 8 min. Additional foaming agents include guar gum (0.45 %), soy protein isolate (3.30 %), and sugar (10 %) with whipping times of 6 min. The optimal conditions for drying Nagpur mandarin juice were determined through analysis using Design-Expert 11.0.4.1 software. These conditions include 540 W of microwave power, a drying bed thickness of 3 mm, and the use of a foaming agent comprising 2.10 % soy protein isolate, 2.75 % GMS, 1.75 % CMC, and 5.10 % sugar, with an 8-min whipping period. Under these optimized conditions, the resulting powder exhibited the following characteristics: color b value of 19.59, ΔE (change in color) of 6.24, acidity of 0.40 %, ascorbic acid content of 36.64 mg/100 g, water activity of 0.26, drying time (in minutes), and overall acceptability rating of 7.77. These findings highlight the effectiveness of the optimized process parameters in achieving desirable quality attributes for Nagpur mandarin juice powder production., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Bi-metallic nanoparticles (NPs) have appeared to be more efficient as antimicrobials than mono-metallic NPs. The fungus Aspergillus terreus-mediated synthesis of bi-metallic Ag-Cu NPs was optimized using response surface methodology (RSM) to reach the maximum yield of NPs. The optimal conditions were validated using ANOVA. The optimal conditions were 1.5 mM total metal (Ag + Cu) concentration, 1.25 mg fungal biomass, 350 W microwave power, and 15 min reaction time. The structure and shape of the synthesized NPs (mostly 20–30 nm) were characterized using several analytical tools. The biological activities of the synthesized NPs were assessed by studying their antioxidant, antibacterial, and cytotoxic activity in different NP concentrations. A dose-dependent response was observed in each test. Bi-metallic Ag-Cu NPs inhibited three clinically relevant human pathogens: Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa. Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus were inhibited less. The DPPH and hydrogen peroxide scavenging activities of the NPs were high, reaching 90% scavenging. Ag-Cu NPs could be studied as antimicrobials in different applications. The optimization procedure using statistical analyses was successful in improving the yield of nanoparticles.

Microwave power and pyrolysis temperature are essential parameters in optimizing the bio-oil yield and quality in microwave pyrolysis. This study focused on understanding the interactions between the microwave power/heating rate and pyrolysis temperature in microwave-assisted pyrolysis of Prosopis juliflora. For optimum bio-oil yield, a discrete set of microwave powers (280 W, 420 W, and 560 W) and pyrolysis temperatures (200 °C, 350 °C, and 500 °C) were selected. A central composite design (CCD) was adopted to analyze the effect of microwave power and the pyrolysis temperature on product yields, heating rate, microwave conversion efficiency, and heat losses in pyrolysis. Moreover, the effect of heating rate, reaction time, specific microwave power, specific microwave energy, and conductive heat loss on gas, char, and liquid yields was evaluated using statistical machine learning techniques. Moreover, a new parameter, pyrolysis index, is calculated under different conditions to understand the extent of pyrolysis intensity using pyrolysis time, heating value, feedstock mass and conversion, and microwave energy conversion. The yields of bio-oil, biochar, and gas were 25–40 wt%, 25–35 wt%, and 35–40 wt% at different experimental conditions. Bio-oil consists of a mix of organic compounds with methoxy phenols at high selectivity, and the calorific value of bio-oil was in the range of 26–28 MJ/kg. Carbon number analysis revealed higher presence of C5–C9 compounds. This study shows the role of machine learning in understanding the effect of various parameters effectively and optimizing the experimental conditions accordingly. [Display omitted] • Optimization of power and temperature in microwave pyrolysis of Prosopis juliflora. • Central composite design was adopted with statistical machine learning analysis. • The yields of bio-oil, biochar, and gas were 25–40 wt%, 25–35 wt%, and 35–40 wt%. • High selectivity of methoxy phenols in bio-oil and HHV was 26–28 MJ/kg. • Pyrolysis index analysis revealed the complete pyrolysis at 420 W for 500 °C. [ABSTRACT FROM AUTHOR]

Detection of methylamines is primarily associated with the quality assessment of seafood. In this context, we report chemi-resistive sensing of methylamine species using α-MoO 3 nanorods synthesized via microwave technique. Investigations were carried out by varying the microwave irradiation power to 300, 450, and 800 W, respectively. Along with the effect of microwave power, the influence of the calcination process on the growth patterns has been emphasized. The un-calcined samples exhibited the formation of triclinic phased ammonium molybdenum oxide ((NH 4) 8 Mo 10 O 34), whereas it gets transformed into orthorhombic phased α-MoO 3 upon calcination. The surface morphology of the un-calcined samples showed the formation of aggregated nanogranular morphology, whereas the calcined samples disclosed the formation of densely populated nanorods. These nanorods were found to be grown with a controlled aspect ratio and twinning dislocations. The influence of twinning dislocations on the grain features and activation energy is reported. The calcined sample prepared at 450 W showed a maximum sensing response of S = 413 towards 200 ppm of trimethylamine (TMA, (CH 3) 3 NH) at room temperature. The observed response towards TMA was 8 times and 5.5 times higher than that of the response observed for monomethylamine (MMA, (CH 3) NH 2)) and dimethylamine (DMA, (CH 3) 2 NH)) respectively. Response/recovery times were found to be 23/12 s, 38/13 s, and 35/11 s towards 1 ppm of MMA, DMA, and TMA, respectively. [Display omitted] • A facile microwave-assisted synthesis of twinned α-MoO 3 nanorods. • Investigations on the role of microwave power in the growth process. • Transformation from (NH 4) 8 Mo 10 O 34 to α-MoO 3 on calcination. • Fabrication of highly selective methylamine sensor using MoO 3 nanorods. • Calcined MoO 3 nanorods prepared at 450 W showed selective response to (CH 3) 3 NH. [ABSTRACT FROM AUTHOR]

To reduce thermal processing hazards (TPHs), microwave baking has been extensively used in food thermal processing. In this study, the influence of microwave power and microwave time on the formation of TPHs and their precursors was explored in microwave-baked biscuits. The results indicated that the content of acrylamide, 5-hydroxymethylfurfural, methylglyoxal, and 3-deoxyglucosone increased linearly with the extension of microwave time (2, 2.5, and 3 min) and microwave power (440, 480, and 520 W). There was a significant correlation between the four TPHs. 3-Deoxyglucosone may directly or indirectly participate in the formation of the other three TPHs. The relationship between TPH levels with some heat-induced sensory characteristics was analyzed. The correlation between the sensory characteristics and the content of TPHs is L * > a * > hardness > Water activity (AW). The correlation coefficients between L * value and the four TPHs are -0.950, -0.891, -0.803, and -0.985. Furthermore, the content of TPHs produced by traditional baking and microwave baking under the same texture level was compared. Compared with traditional baking (190°C, 7 min), microwave baking at 440 W for 3 min successfully decrease methylglyoxal, 3-Deoxyglucosone, acrylamide, and 5-hydroxymethylfurfural content by 60.75, 30.19, 30.87, and 61.28%, respectively. Traditionally baked biscuits, which had a more obvious color, as characterized by lower L * value, larger a * and b * values, are more susceptible to the formation of TPHs. Therefore, microwave baking can reduce the generation of TPHs., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Dong, Qiu, Wei, Yu, Zhang and Wang.)