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We rely on polymer foams to build things from tissue engineer scaffold to airplanes. Still, traditional polymer foaming methods usually involve chemical agents or high-pressure gases, which can cause environmental and safety concerns. Therefore, we developed a novel microwave foaming method that uses only microwave irradiation as the driving force of foaming and water as the blowing agent. Using the microwave foaming method, we managed to generate polymer foams based on polyvinyl alcohol (PVA) within minutes. We also conducted experiments to study the influence of processing parameters on cell structures, such as the influence of microwave power and the initial water content, which shows that this method is controllable and has the potential to replace traditional foaming methods in future industrial application scenarios.

The microwave remediation technology of organic contaminated soil is a potential developed technology. In this work, nitrobenzene was used as a simulated organic pollutant, and bluecoke powder, a by-product from coal pyrolysis, was employed as a microwave absorber to research the effects of microwave power, heating time, soil capacity, nitrobenzene load, and BC amount on the removal rate of nitrobenzene in soil. Results showed that the characteristics of heating temperature were improved, including temperature-rising rate and final heating temperature. The effects of the above experimental conditions on the removal rate were evident, especially in microwave power, heating time, and nitrobenzene load. When the microwave power was 700 W, the heating time was 600 s, the soil capacity was 50 g, the nitrobenzene load was 5 wt%, and the BC amount was 2 wt%. The removal rate of nitrobenzene was approximately 80%, which was 6.25 times that without BC. The removal process of nitrobenzene during microwave remediation showed that most nitrobenzene in soil was gasified during microwave heating, and a portion of the escaped vaporized nitrobenzene was decomposed. In addition, 100% of the removal rate could be an achievable goal through adjusting and controlling the remediation.

Microwave plasma chemical vapor deposition (MPCVD) has received tremendous research interest in fabrication of carbon nanotubes (CNTs) due to its unique advantages of high reactivity, rapid heating, no pollution, good controllability, etc. It would be meaningful to summarize the efforts that have been devoted in this area. Up to now, no such review has been seen in the literature. In this review, a summarization and discussion of the MPCVD devices applied in CNTs fabrication are firstly given, followed by the discussion on effect and affecting mechanisms of H2 plasma pretreatment, nitrogen atoms in the reacting gases and microwave power. Notably, the parameters of as-synthesized CNTs products and the corresponding synthesizing MPCVD conditions are listed out. Finally, the capabilities of MPCVD in facilitating atmospheric-pressure, low-temperature and in situ growth of CNTs are reviewed. This review can give a comprehensive grasp of current progress and understanding of MPCVD in preparation of CNTs and may provide a useful guidance for readers to design their fabricating systems to obtained required CNTs using MPCVD.

Being a seasonal fruit mango cannot be cherished over the year; dehydration may be a solution to preserve the deliquesce of mango as mango leather. The processing parameters like puree load (0.4–0.6 g/cm2), total soluble solid (20–30 °B), oven temperature (60–80 °C), and microwave power level (100–300 W) were optimised for a superior textural attribute (hardness) primitive drying method like sun drying, industrially practiced modern methods like hot air oven drying and microwave drying and cutting-edge drying technique like freeze-drying. Response surface methodology and artificial neural network technique were adapted to model these drying procedures by considering the central composite design. The mathematical operations guiding to describe the model were studied. Being an imperative parameter colour quantification is essential for food industries. Current research employs microwave drying to produce mango leather with colour quantification approach. The L, ‘a’ and ‘b’ values of the product have been measured by Hunter Lab colorimeter and by digital image analysis, to determine the chromatic view harmonious to human vision. The relative analysis of colour measurement through these two techniques has been studied.

Betacyanin and betaxanthin are natural colouring compounds found in Amaranthus tricolour leaves. Microwave-assisted extraction was performed to extract betacyanin and betaxanthin from the unsalable leaves. A set of different process parameters like microwave power, temperature and time was applied in this study. The combination of 450-W microwave power, 90 °C temperature and 15 min of extraction time resulted in the highest amount of betacyanin (71.95 mg/g of dw) recovery. The highest amount of betaxanthin (42.30 mg/g of dw) was extracted at 200-W microwave power, 60 °C temperature and 15 min of extraction time. Green extraction was done by using water as the solvent based on the solubility of compounds being highest in it. The combined effect of time and temperature was also found to be significant for the extraction. The betacyanin and betaxanthin also exhibited good scavenging ability against superoxide and hydrogen peroxide. The recovery was maximum at higher temperatures with a shorter time of extraction. The SEM images showed that the plant matrix ruptured due to microwaves. The FTIR spectroscopy showed the existence of betacyanin and betaxanthin in the leaf extract. The microwave technique was also proved to be better than ultrasound extraction and Soxhlet extraction. The colour change in the powdered sample was observed after extraction which shows the efficient recovery of pigments. The A. tricolour leaves are the cheaper source of betacyanin and betaxanthin. These compounds not only possess colouring properties but also exhibit antioxidant and medicinal properties. Hence, betacyanin and betaxanthin extracted from these leaves can be used as additives and colourants in food products.

The present work deals mainly with dehydration characteristics of onion slices. Microwave power levels of 100, 350, 550 and 750 W was practiced to dry onion slices with thicknesses of 2.5, 5, 7.5 and 10 mm. The results showed that moisture diffusivity and specific energy consumption of the process increased with both increasing microwave power and the samples thickness, and ranged from 0.82 × 10−8 to 6.13 × 10−8 m2 s−1 and from 0.82 to 5.43 MJ kg−1 water, respectively. The average activation energy varied in the range of 1.28–1.77. Furthermore, for simulation of drying process and to predict the moisture removal behavior of the samples, multi-layer feed-forward (MLF) artificial neural network (ANN) was employed. Practicing different networks and based on statistical parameters, the best topology, transfer functions and training algorithms were determined. The results revealed that, as a powerful tool, ANN modeling could be effectively used to predict drying kinetics and determine the moisture content of the samples.

The main focus of this study was to develop and calibrate a computerized image analysis system in order to measure the color of banana (Musa Cavendish) under microwave treatment. Bananas were cut into 2 mm slice thickness and dried at two different microwave power level; 540 W and 180 W. An algorithmic was developed which converted RGB color value from a color image into CIE L*a*b* values very well (Error(L*) = 2.163%, Error(a*) = 4.458%, Error(b*) = 5.224%). Once the calibration is completed, it was applied to measure the color change in the banana slice during drying. The value of L* decreased from 89.01 to 71.17 and from 82.60 to 72.53 for both microwave treated samples suggesting browning is taking place during the drying operation. The value of a* increased from − 0.80 to 11.50 and from − 3.90 to 5.18 for 540 and 180 W microwave treated banana slices respectively suggesting tendency of redness increased. The same type of increment was observed for b* value. It changed from 36.46 to 60.51 and 34.02 to 72.82 for 540 and 180 W microwave treated banana slices, respectively. Artificial Neural Network (ANN) modeling was used for prediction of the developed CVS’s values.

The influence of intermittent-microwave drying and hot-air drying on drying characteristics and rehydration properties of apple slices were compared. Microwave powers have crucially affected the drying rate, effective moisture diffusivity and drying time. As microwave power increased, the drying rate and effective moisture diffusivity increased while the drying time reduced. In intermittent-microwave drying, the effective moisture diffusivities were estimated between 4.47 × 10-9 and 2.54 × 10-8 m2 s-1. Longer drying time, slower drying rate and less effective moisture diffusivity were obtained from hot-air drying when compared to intermittent-microwave drying. Higher temperatures provided higher drying rate and effective moisture diffusivity. Effective moisture diffusivities of hot-air dried-apple slices were calculated in the range of 3.38 × 10-10–6.25 × 10-10 m2 s-1. Moreover, Page model gave the best fitting to intermittent-microwave drying curves, while hot-air drying curves were suitably described by Parabolic Model. On the other hand, the rehydration ratio of intermittent-microwave dried-apple slices was higher than hot-air dried-apple slices. Additionally, Peleg model was defined to be the best model predicting experimental rehydration data in both drying techniques. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.

Microwave-assisted extraction (MAE) and solvent-free microwave extraction and Soxhlet extraction were applied to Ray Ruby grapefruit leaves (Citrus paradisi Macf.) to compare extract efficiency. Face centered composite designs were constructed via response surface methodology. Effects of factors of MAE were investigated on total phenolic content (TPC) and naringin content (NC). The optimized conditions were established as 1.4 kWL−1 for microwave power density, 20.00 gL−1 for solid/solvent ratio, 218.180 s for extraction time, while responses were calculated as 14.210 mg of gallic acid equivalent per g of the dried leaf (mg GAE g−1DL) and 13.198 mg of naringin per g of dried leaf (mg Ng−1DL) for TPC and NC, respectively. SFME and classical Soxhlet methods were also conducted for comparison reasons.

The current loading of an accelerated electron beam in the accelerating fields of a LUE-200 linear accelerator of the IREN facility at the Joint Institute of Nuclear Research (Dubna) is discussed. The LUE-200 accelerator consists of two accelerating sections operating on a traveling wave at a frequency of 2856 MHz with the microwave power compression systems of the SLED type. The limits of the accelerated beam current values are determined for various pulse durations of the beam current and microwave power levels fed into the accelerating sections. The calculation results are compared with the measured data.

Coconut inflorescence sap, traditionally called as neera, is a natural and healthy drink obtained by tapping the unopened immature spadix of coconut. The sap tapped by using the device coco-sap chiller, developed by ICAR-Central Plantation Crops Research Institute, is called Kalparasa®. The shelf life of the sap after extraction is 2–3 h in atmospheric condition. Farmer producer companies and palm sap processing industries require suitable preservation techniques to maintain the physico-chemical properties of the coconut sap. Hence, the effect of microwave power level (600 and 900 W) and exposure time (30, 60, 90, and 120 s) on the physico-chemical properties of Kalparasa stored under refrigerated conditions was investigated. The physico-chemical properties of microwave-treated Kalparasa including pH, TSS, titratable acidity, ascorbic acid, total sugar, reducing sugar, and polyphenols were analysed at 1, 3, 5, 7, 9, 12, and 16 days after storage. The results reveal that the microwave treatment and storage period had a significant effect (P

Microwave assisted concrete recycling is highlighted by a large number of research groups all over the world due to its potential for significant process benefit. In this paper, systematic experiments are established to study the microwave heating and aggregate recycling of dried and saturated concrete, respectively, investigating the effect of moisture content on heating results. The heating characteristics, cracks propagation, concrete damage and micro-structure variations were demonstrated. The temperature was higher in dried concrete under microwave heating, while the concrete damage and mortar-aggregate interface debonding were firstly occurred in saturated concrete. Recycled aggregates could be obtained by the combinations of mechanical process and microwave treatment in dried sample. While in saturated concrete, aggregates could be easily separated under relatively sufficient microwave power input. The results show that water content has the vital influence on concrete heating and aggregate separation results. The properties of recycled aggregates were tested to evaluate its further applications. The experimental results can provide a new approach to improve the microwave-assisted concrete aggregate recycling efficiency through the increment of water content.

We examined the influence of the microwave power on the diagonal resistance in the GaAs/AlGaAs two dimensional electron system (2DES), in order to extract the electron temperature and determine microwave induced heating as a function of the microwave power. The study shows that microwaves produce a small discernable increase in the electron temperature both at null magnetic field and at finite magnetic fields in the GaAs/AlGaAs 2DES. The heating effect at null field appears greater in comparison to the examined finite field interval, although the increase in the electron temperature in the zero-field limit appears smaller than theoretical predictions.

Food irradiation is used to preserve food from pathogenic microorganisms, deterioration and to extend shelf life. The EU legislation states that any irradiated food or food ingredients must be labeled with the word “irradiated”. The ESR spectroscopy is a powerful tool to enhance official checks; hence, it has been used to detect irradiated hazelnuts. The results from the ESR studies on hazelnuts before and after X-ray irradiation are reported. Before irradiation hazelnuts exhibit one singlet ESR line characterized with a g-factor of 2.0046 ± 0.0006. After irradiation, a typical “cellulose-like” triplet ESR spectrum appears. To investigate the radio-induced free radical stability, the peak-to-peak amplitude of the ESR satellite signals was considered. Fading measurements indicate that the intensity of the ESR spectra of hazelnuts is reduced to about 70% after 30 days. In addition, the microwave power behavior and a dose–response relation were investigated. The study confirmed the applicability of ESR technique to detect irradiated hazelnuts also when a long time after treatment was passed.

In the present work, the influence of microwave power and samples thickness on drying behavior, moisture diffusivity and energy consumption of potato slices was studied. The slices with thicknesses of 3.5, 5, 7 and 9 mm were dried as mono layers at four different power levels (200, 400, 600 and 800 W). The results showed that the process time was significantly (P

Optimization of microwave and infrared drying processes of nettle leaves was investigated using dependent variables of drying time and phenolic composition of nettle extracts. The response surface method was selected for design and optimization of the processes. Experiments were performed at different microwave power levels (180, 360, 540, 720 and 900 W) and infrared lamp distances to samples (4, 5.5, 7, 8.5 and 10 cm). The results showed that the drying time (t) decreased and the amount of total phenolic contents (TPC) of nettle extracts increased with an increase in microwave power and also increasing infrared lamp distance to the sample increased the drying time of the samples and decreased the amount of total phenolic contents of nettle extracts. Based on response surface and desirability functions, the optimum conditions for nettle leaves drying were: microwave power 900 W and infrared lamp distance 4 cm. At this point, t and TPC were obtained as 3.014 min and 38.81 mg/g for microwave dryer and 7.73 min and 36.45 mg/g for infrared dryer, respectively.

The aims of this study were to determine (1) the effects of microwave irradiation on the drying kinetics of jack pine wood, (2) the phytosanitary efficacy, and (3) the processing energy consumption and mechanical strength of the dried product. Microwave drying experiments were performed at 2.45 GHz frequency and at microwave powers ranging from 300 to 1000 W. Results indicate that higher microwave power and initial wood temperature and lower sample thickness increases the internal sample temperature, improves the drying rate, and reduces both drying time and energy consumption. The microwave irradiation efficacy to sanitize jack pine wood boards was determined in terms of temperature/time combinations based on actual drying kinetics according to standards for phytosanitary measures. The energy required to dry 12 mm thick wood board samples at microwave power ranging from 300 to 1000 W was in the range of 36.4–12.3 MJ/kg of water, respectively, for up to 65% energy consumption savings. The impact of microwave power on the mechanical properties was not statistically significant, although mechanical properties tended to decrease with increasing power.

In order to investigate the temperature characteristics of wood during microwave (MW) treatments, optical fiber sensors were used to measure wood (Pinus sylvestris L. var. mongolica Litv.) temperatures. The results show that the development of internal temperatures in wood basically includes two patterns during the process of MW treatment. The first may be divided into three phases: warming, constant temperature, and a sharply rising phase. The second pattern may be divided into two phases: warming, and constant temperature. The maximum temperature (MT) and rate of temperature increase (RTI) rose as the microwave power increased. The initial wood moisture content decreased while the period of constant temperature fell. Temperatures varied in different positions in the wood. The order of MT and RTI levels were the upper surface, center, bottom surface and the end point. Along the direction of wood thickness, the closer the monitoring point was to the generator, the faster the temperature increased. The MT and RTI of the end point was a minimum value because of the rapid removal of steam.

The hydrogen dissociation and its effect on the GaN film growth in the ECR-PECVD process are investigated in this paper. We use N2 and trimethylgallium (TMG) as N and Ga sources respectively in the ECR- PECVD process. The results show that the rate of hydrogen dissociation increases with the microwave power and it becomes higher at high microwave power (> 500 W). However, this population increase of the H species dissociated from the TMG gas in ECR plasma is not enough to change the growth condition from Ga-rich to N-rich.

Microwave is a useful and proven tool for increasing permeability of refractory wood and, thereby, it can be used for reducing drying time and defects. However, strength loss is always a concern. In this study, green timber boards were treated with microwave in two intensities, low microwave (LMW), 89 kWh/m3, and high microwave (HMW), 95 kWh/m3, and compared with control boards. Samples of all three treatments were kiln dried together. Density and selected mechanical properties were also assessed after drying. LMW, the treatment which presented the best results, showed reduction in some drying defects, such as collapse (20%), surface check length (84%), internal check length (50%) and internal check width (70%). Density, MOE and MOR on static bending were unchanged, whereas reductions in shear strength (13%) and compression strength parallel to grain (10%) were observed. HMW, on the other hand, produced higher strength reductions and more drying defects than LMW. Fine adjustments of LMW microwave power might bring drying benefits without strength losses.

Effects of both hybrid (HD; microwave-convectional) and convectional (CD) drying on total phenolics content (TPC), antioxidant capacity (AOC), vitamin C content, color, rehydration capacity, texture profile analysis and sensorial properties of apricots were investigated. Apricots were dried by CD at 50, 60, 70 °C and by HD at various microwave power levels (120, 150, 180 W) coupled with hot-air (50, 60, 70 °C) during the whole drying process. Hybrid-dried apricots had better retention of these bioactive compounds than that of CD. L * and b * values decreased with the increase in air temperature and microwave power. Hybrid-dried apricots had greater rehydration capacity than convection-dried ones, especially at higher microwave powers. Hardness and chewiness increased with increase in air temperature and microwave power while cohesiveness decreased. It was found from the Pearson correlation test that a significant relationship was observed between TPC and AOC, TPC and vitamin C; AOC and L *, a *, b *, and ΔE, respectively of hybrid-dried apricots. When all these aspects are considered, hybrid drying could be an alternative method for drying of apricot.

Ultrasonic-microwave assisted extraction (UMAE) was employed to extract total flavonoids (TF) from Scutellaria baicalensis roots. Single-factor experiments to evaluate effects of the process parameters (solvent-to-material ratio, ethanol concentration, extraction time, ultrasonic power, microwave power, and extraction temperature) on the TF yield were performed, and the response surface methodology (RSM) was used to optimize the extraction parameters. The optimum conditions to obtain the maximum TF yield were as follows: solvent-to-material ratio, 24; ethanol concentration, 52%; extraction time, 15.0 min; extraction temperature, 62.0°C; ultrasonic power and microwave power, 300 W each. The TF yield under these conditions reached 8.71 ± 0.26%. The analysis of variance and validation test indicated that the proposed method is useful and reliable.

The heating characteristics of magnetite ore under microwave irradiation were investigated as a function of incident microwave power, particle size, and magnetite ore mass. The results showed that the heating rate of magnetite ore is highly dependent on microwave power and magnetite ore mass. The maximum heating rate was obtained at a microwave irradiation power of 1.70 kW with a mass of 25 g and particle size between 53-75 µm. The volumetric heating rate of magnetite ore was investigated by measuring the temperature at different depths during microwave irradiation. Microwave irradiation resulted in modification of the microstructure of the magnetite ore, but new phases such as FeO or Fe2O3 were not formed. In addition, the crystal size decreased from 115 nm to 63 nm after microwave irradiation up to 1573 K.

Mussels (Mytilus edulis) can be consumed as an alternative food product for several meats, such as beef and fish, due to their high protein content. In this study, several microwave power levels (90, 180, 360, 600 and 800 W) were applied to Mytilus edulis to determine their effect on drying kinetics, rehydration characteristics and energy consumptions. The optimal drying times of 16, 5 and 2 min were determined for microwave power levels of 90, 180 and 360 W, respectively. However, at the microwave power levels of 600 and 800 W, the optimal drying times were 80 and 60 s, respectively. The experimental results indicate that the drying kinetics, rehydration characteristics and energy consumptions are slightly affected by the change in microwave power levels. Seven different thin-layer drying models that are widely used in the literature were applied to the experimental data. The results showed that the Weibull model best fits the experimental data (R 2: 0.998135–0.999929, χ 2: 0.000029–0.000401, and RMSE: 0.004172–0.018733) of the drying kinetics of Mytilus edulis. The effective moisture diffusivity was determined to be between 2.74 × 10−8 and 4.79 × 10−7 m2/s. Using a modified Arrhenius-type equation, the activation energy was found to be 95.131 kW/kg. The microwave power level of 360 W was found to be the most effective, considering the minimum energy consumption.

Since snacks high in fats are known to be a significant source of fat and energy intake, these have been put in high dietary restraint category. Therefore, an attempt was made to process potato chips through microwave processing without incorporation of any oil in potato chips. Microwave processing of potato chips was done using microwave power varying from 180 to 600 W using constant sample size. Among eleven different drying models, Parabolic model was found to be the best fit through non-linear regression analysis to illustrate drying kinetics of potato chips. The structural, textural and colour attributes of microwaved potato chips were similar to commercial fried potato chips. It was found that at 600 W after 2.5-3.0 min of processing, potato chips gained the fracturability and crispiness index as that of commercial fried chips. Microwave processing was found suitable for processing of potato chips with low fat content (~3.09 vs 35.5 % in commercial preparation) and with acceptable sensory scores (≥7.6 on 9.0 point on hedonic scale vs 8.0 of control preparation).

The present work illustrates the Microwave-Assisted Drying (MWAD) characteristic of aloe vera gel combined with process optimization and artificial neural network modeling. The influence of microwave power (160–480 W), gel quantity (4–8 g) and drying time (1–9 min) on the moisture ratio was investigated. The drying of aloe gel exhibited typical diffusion-controlled characteristics with a predominant interaction between input power and drying time. Falling rate period was observed for the entire MWAD of aloe gel. Face-centered Central Composite Design (FCCD) developed a regression model to evaluate their effects on moisture ratio. The optimal MWAD conditions were established as microwave power of 227.9 W, sample amount of 4.47 g and 5.78 min drying time corresponding to the moisture ratio of 0.15. A computer-stimulated Artificial Neural Network (ANN) model was generated for mapping between process variables and the desired response. ‘Levenberg–Marquardt Back Propagation’ algorithm with 3-5-1 architect gave the best prediction, and it showed a clear superiority over FCCD.

The present study investigated the drying kinetics of taro slices precooked in different medium viz water (WC), steam (SC) and Lemon Solution (LC) and dried at different microwave power 360, 540 and 720 W. Drying curves of all precooked slices at all microwave powers showed falling rate period along with a very short accelerating period at the beginning of the drying. At all microwave powers, higher drying rate was observed for LC slices as compared to WC and SC slices. To select a suitable drying curve, seven thin-layer drying models were fitted to the experimental data. The data revealed that the Page model was most adequate in describing the microwave drying behavior of taro slices precooked in different medium. The highest effective moisture diffusivity value of 2.11 × 10−8 m2/s was obtained for LC samples while the lowest 0.83 × 10−8 m2/s was obtained for WC taro slices. The activation energy (E a ) of LC taro slices was lower than the E a of WC and SC taro slices.

Benzathine penicillin G (BPG) in powder form was exposed to a range of different doses of 60Co gamma radiation to investigate the effects of ionizing radiation using electron paramagnetic resonance (EPR) technique. Dependence of EPR signals with absorbed dose, time, temperature and microwave power were studied. In the light of the findings on all EPR experimental data, it can be suggested the radiosterilization of BPG in solid dry state could be technically feasible by EPR method.

In this investigation, (1,8-diamino-3,6-dioxaoctan)copper(II)sulfate, ([Cu(DADO)]SO4), bis(propylenediamine)copper(II)sulfate, and ([Cu(pn)2]SO4) were applied as copper precursors to fabricate CuInS2 (CIS) nanostructures in presence of microwave irradiation. Besides the effect of copper precursor, the effect of microwave power and time of irradiation on morphology of CuInS2 nanostructures were investigated. The as-prepared products were analyzed by XRD, PL, FT-IR, EDS, and SEM. The results of XRD patterns were indicated that pure CuInS2 with tetragonal phase could be only obtained after annealing at 400 °C for 2 h in a mixture of 85 % Ar and 15 % H2 gases. SEM images were shown that regular hierarchical nanostructures of CuInS2 were obtained with the aid of [Cu(pn)2]SO4 as copper precursor under 900 W irradiation power for 12 min. The photovoltaic behaviors of as-synthesized CuInS2 nanostructures were studied after deposition of CdS film on chemical bath. CuInS2 film was directly deposited on the surface of the CdS film through doctor blade method. The as-deposited CdS/CuInS2 films were applied in photovoltaic measurements.

Coaxial power calibrators and ways of improving them for checking terminal-type wattmeters are considered. Measurement of the complex effective reflection coefficient $$ {\dot{\Gamma}}_{\mathrm{eff}} $$ of the output of the calibrators enables the Γ-correction method to be used when transmitting the unit of power by the direct comparison microwave method, which considerably reduces the mismatch error. The errors in measuring $$ {\dot{\Gamma}}_{\mathrm{eff}} $$ are analyzed and the results of measurements by different methods are compared. An automated system for checking wattmeters using Γ-correction is described.

Pomegranate arils (Punica granatum L.) were dried in a microwave-vacuum drier up to a final moisture content of around 5–6 % (d.b.). The effect of microwave power level (25–95 W), vacuum pressure (25–195 mm Hg) and sample mass (65–235 g) on drying efficiency and some quality attributes (color, texture, rehydration ratio and sensory score) of dried pomegranate arils were analyzed by means of response surface methodology. A rotatable central composite design was used to develop models for the responses. Analysis of variance showed that a second order polynomial model predicted well the experimented data. All three process parameters microwave power, vacuum pressure and sample mass strongly affected quality attributes of dried pomegranate arils and drying efficiency. A lower vacuum pressure during drying resulted in better quality products. Optimum drying conditions of microwave power level of 80 W, vacuum pressure of 60 mm Hg and sample mass of 193.7 g were established for microwave-vacuum drying of pomegranate arils. Separate validation experiment was conducted at the derived optimum conditions to verify the predictions and adequacy of the models.

Microwavable products are gaining worldwide acceptance as convenience foods, where hygiene can be maintained when processed in small quantities at the domestic level. One such ready to eat products are puffed or popped starchy grains like corn, rice, sorghum, etc. Owing to its high starch content, rice has high expandability, and the puffed rice produce thence has better digestibility. Considering these aspects, an attempt was made to produce puffed rice in a domestic convective–microwave oven. Puffing characteristics were studied for Gurjari variety of rice at 14 % (wb) moisture content for different preheating temperatures of the glass base plate (180, 200, and 220 °C), microwave power level (300, 600, and 900 W), and residence time (10–100 s), from which the range of residence time was selected for the optimization study. It was found that the puffing of rice was better at higher power level and preheating temperature of the base plate, and puffing started only after certain residence time. Further study was carried out to optimize the process parameters by using response surface methodology, for a Box–Behnken design at three levels for four parameters, i.e., moisture content (12, 14, and 16 % wb), preheating temperature of the base plate (180, 200, and 220 °C), microwave power level (300, 600, and 900 W), and residence time (50, 60, and 70 s). The optimized conditions were found to be 14 % (wb), 220 °C, 900 W, and 60 s. The second-order polynomial model was validated by conducting three trials at the optimized point and found to be agreeing with the predicted values.

Microwave-assisted extraction (MAE) in the presence of ethanol and water as solvents was applied as a modern technique to extract polyphenolic compounds from apple pomace and the results were compared to those of Soxhlet extraction and maceration. Various experimental conditions such as microwave power, extraction time, type of solvent, and solvent to sample ratio were considered for the study. Increasing microwave power (from 90 to 360 W) resulted in lower extraction yields. Ethanol-water (at the ratio of 65 to 35) was the best solvent for MAE. However, for the sake of higher water contribution in the extraction, a ratio of 35:65 (ethanol:water) can be selected for a recovery of −90% at a shorter extraction time. The best solvent to sample ratio was found at 20 to 1 level. When used for the extraction of polyphenolic compounds from apple pomace, MAE was faster than maceration and Soxhlet methods.

Polyphenols in mulberry fruit were fast extracted using a microwave-assisted extraction technique, and the effects of process variables including the solvent concentration, irradiation time, microwave power, and solvent consumption upon polyphenol extraction were investigated. Fifteen runs rotatable box-behnken design (RBBD) with three variables and three levels were employed; optimal conditions and maximal yields of the total polyphenol and flavonoid contents were predicted by generating a mathematical polynomial model based on response surface methodology. The estimated optimal conditions were ethanol concentration of 40%, irradiation time of 8 min, and microwave power of 210 W. A verification experiment was carried out at the above mentioned optimal conditions, and no significant differences were observed between the predicted and experimental values, which confirmed that the prediction was valid and application of response surface methodology (RSM) to the extraction of polyphenols and flavonoids from mulberries under microwaveassisted extraction (MAE) process was successful. In addition, specific polyphenols contained in mulberries were identified and quantified using high performance liquid chromatograph.

In this study, arils of Hicaz type pomegranates were dried by hot air and microwave drying technique. Drying behavior, shrinkage, rehydration, bulk density and color changes of the products were investigated. Hot air drying process was carried out at three different temperatures; 50, 60 and 70 °C at 1.0 m/s air velocity. Also, three microwave power levels (210, 350, and 490 W) were studied as another drying technique. Among the several models listed in literature, the Page drying model was appropriate for both convective and microwave drying of the pomegranate arils drying. Increasing drying temperature and power intensity shortened the drying time of arils. Rate of drying was higher when microwave (5.83 × 10−3 - 2.85 × 10−2) used compared to air drying process (1.52 × 10−4 - 1.70 × 10−3). It was observed that shrinkage of air dried samples was higher than microwave dried sample. Rate of rehydration of microwave dried aril samples was relatively faster than air dried samples, but not significant statistically. However, bulk density of air dried samples was higher than those of microwave dried sample.

Nobiletin (NOB) is a well-known polymethoxylated flavone that has only been found in citrus. The objective of this study is to obtain the optimal conditions for extracting nobiletin from sweet orange residues by microwave-assisted extraction (MAE) using response surface method. By using the Box-Behnken experimental design and SAS software 3 independent variables including solid/solvent ratio, microwave power, and treatment time were examined for the response variable nobiletin extraction yield. The regression Eq. 7 statistically significant (p

We examine the microwave reflection from the high mobility GaAs/AlGaAs two-dimensional electron system (2DES). Strong correlations have been observed between the microwave induced magnetoresistance oscillations and the microwave reflection oscillations in a concurrent measurement of the microwave illuminated magnetoresistance and the microwave reflection from the 2DES. The correlations were followed as a function of the microwave frequency and the microwave power dependent. Different existing theories are considered to explain the results.

A theoretical analysis of a method of reducing the mismatch error that arises when transferring the unit of power is presented. Methods of estimating the uneliminated systematic mismatch error and areas of their application are proposed.

Paramagnetic centers in the three glucocorticosteroid drugs, such as betamethasone, clobetasol, and dexamethasone, were examined by the use of X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. Glucocorticosteroid drugs were sterilized according to the norms at 160 °C (120 min), 170 °C (60 min), and 180 °C (30 min). Free radical properties, types, and concentrations in the individual glucocorticosteroids were compared. The lineshape and parameters of EPR curves recorded in the range of the microwave power of 0.7–70 mW were tested. The non-heated drugs were diamagnetic. Free radicals were formed in clobetasol and dexamethasone drugs during process of their thermal sterilization, while free radicals were not detected in thermally sterilized betamethasone. Fast spin–lattice relaxation processes existed in heated clobetasol and dexamethasone. Their EPR lines were homogeneously broadened. A complex free radical system characterized these two drugs. Optimal conditions of sterilization of glucocorticosteroids were obtained. Betamethasone may be sterilized at 160, 170, and 180 °C. Clobetasol may be sterilized at 160 and 170 °C. Dexamethasone may be sterilized at 170 and 180 °C.

A microwave-assisted extraction method has been developed for the extraction of phenolic compounds from the green alga, Caulerpa racemosa. An L18(3)5 orthogonal experimental array was designed to optimize the extraction conditions. Total phenolic content was determined by Folin–Ciocalteu method. Under the optimized conditions (microwave power, 200 W; ethanol concentration, 60%; extraction time, 40 min; extraction temperature, 50°C; solvent-to-material ratio, 40 mL g−1), the maximum total phenolic content reached 67.89 ± 3.88 mg 100 g−1 dried sample. The crude ethanolic extract was further purified by liquid–liquid partition to afford two fractions, of which the ethyl acetate-soluble fraction (EAF) exhibited the strongest antioxidant activity in the hydroxyl and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays and reducing power. EAF was further divided into four subfractions, designated as EAF1 to EAF4, by silica gel vacuum liquid chromatography. The antioxidant capacity of the subfractions was in the following order: EAF1>EAF2>EAF4>EAF3. The results of IR spectral and HPLC analysis, including the research on the correlation between antioxidant capacity and total phenolic content, suggested that phenolic compounds of medium polarity were the major contributors to the antioxidative activity of C. racemosa. The present findings might contribute to a rational basis for the use of phenolic-rich fractions and subfractions as natural antioxidants in different food/pharmaceutical products.

Microwave irradiation as a means for heating bentonites during acid activation has been investigated in the past but it has never been optimized for industrial applications. The purpose of this study was to apply a factorial 2(3) experimental design to a Serbian bentonite in order to determine the influence of microwave heating on the acid-activation process. The effect of acid activation under microwave irradiation on the textural and structural properties of bentonite was studied as a model reaction. A mathematical, second-order response surface model (RSM) was developed with a central composite design that incorporated the relationships among various process parameters (time, acid concentration, and microwave heating power) and the selected process response of specific surface area of the bentonite. The ranges of values for the process parameters chosen were: time, 5-21 min; acid concentration, 2-7 M; and microwave heating power, 63-172 W. The effect of individual variables and their interaction effects on the textural and structural properties of the bentonite were determined. Statistical analysis showed that the duration of microwave irradiation was less significant than the other two factors. The model showed that increasing the time and acid concentration improved the textural properties of bentonites, resulting in increased specific surface area. This model is useful for setting an optimum value of the activation parameters for achieving the maximum specific surface area. An optimum specific surface area of 142 m(2)g(-1) was achieved with an acid concentration of 5.2 M, activation time of 7.4 min, and microwave power of 117 W.

Samples of normal, high-amylose, and waxy barleys (NB, HAB, and WB, respectively) were tempered and then microwaved using three treatment protocols at each of three power levels. Microwave treatment increased starch digestibility, as rapidly digestible starch (RDS) concentrations were markedly higher and resistant starch (RS) and slowly digestible starch (SDS) concentrations were significantly lower, in all microwaved samples compared to corresponding unprocessed samples. Levels of RDS, on a dry sample basis, were similar in corresponding microwaved samples of the three barley types but were higher in WB when expressed on a starch basis. Levels of RS were lowest in microwaved WB samples. Microwave treatment was most effective in increasing starch digestibility at higher microwave power levels and when samples were tempered and then stored for 14 days at 4°C prior to microwaving, although the magnitude of the increase may not justify the cost of the storage step and might be achieved more economically through the use of an even higher power level. Increases in starch digestibility were attributed to gelatinization of starch. This conclusion was supported by degree of starch gelatinization, thermal analysis, and pasting data.

The literature surveyed revealed that drying kinetics of white mulberry under microwave treatment has not been investigated. In present study, both experimental study and mathematical modeling on microwave drying of white mulberry was performed. The microwave drying process which reduced the moisture content of mulberry from 3.76 to 0.25 (g water/g dry matter) was carried out at 90, 180, 360, 600, and 800 W in a modified microwave drying set-up. The effects of microwave drying technique on the moisture ratio and drying rate of white mulberry were investigated experimentally. Both the effects of microwave power level (under the range of 90–800W) and initial sample weight (50–150g) were studied. No constant rate period was observed. Mathematical modeling of thin layer drying kinetics of white mulberry under microwave treatment was also investigated by fitting the experimental drying data to eight thin layer drying models. Among the models proposed, Midilli et al. model precisely represented the microwave drying behavior of white mulberry with the coefficient of determination higher than 0.999 and mean square of deviation (χ2) and root mean square error (RMSE) lower than 1.1×10−4 and 8.9×10−3, respectively for all the microwave drying conditions studied. The effective moisture diffusivity (Deff) of white mulberry varied from 0.45×10−8 to 3.25×10−8 m2s−1. Both the drying constant (k) and Deff increased with the increase of microwave power level.

The main objective of this study was to determine the effect of microwave thawing at different power levels on the physicochemical properties of chicken breast. Each frozen chicken breast samples were thawed in microwave oven at microwave power levels of 125, 250, and 375W. To compare the effect of microwave thawing on meat quality, refrigerator thawing was used as a control. As the microwave power level increased, the thawing rate increased and temperature differences between the edge position and center position of the samples also increased. Treatment at a power level of 250 W resulted in a lower thawing loss and a higher moisture content, water holding capacity, and tenderness than the other treatments (p

An X-band AlGaN/GaN high-electron-mobility transistor (HEMT) on SiC substrate with high microwave power performances has been achieved. Its small-signal characteristics with a gate-length of 0.4 μm showed a unity current gain cut-off frequency (fT) of 22 GHz and a maximum oscillation frequency (fmax) of 65 GHz. The GaN HEMT device with a gate width of 1 mm exhibited a continuous-wave saturated output power of 10.2 W and a linear gain of 14.8 dB at 8 GHz, and successfully achieved the power-added efficiency (PAE) as high as 69.2%, which is very suitable for X-band power applications.

Active components in Chinese quince were extracted by using high efficient microwave-assisted extraction. In accordance with central composited design, 20 runs with 3 variables and 5 levels applied for the optimization in response surface methodology system. The extracts were analyzed by spectrophotometeric methods for the total flavonoids content (TFC), total phenolic compound (TPC) and electron donating ability (EDA). The optimum conditions obtained were 44.15% ethanol concentration, 5 min extraction time and 102.1 W microwave power for maximum TFC (477.8 mg RE/100 g), TPC (2249 mg GAE/100 g) and EDA (77.47%) as predicted by overlaid contour plots.

A new hybrid drying technique by combining microwave and forced convection drying within a rotary drum, i.e., microwave rotary drying, was developed with the purpose to improve the uniformity of microwave drying. In a laboratory microwave rotary dryer, rewetted soybean was utilized as experimental material to study the effects of drum rotating speed, ventilation flow rate, and specific microwave power on the drying kinetics and cracking ratio of soybean. It was found that, with rotation, the cracking ratio can be lowered but without distinct improvement in the drying rate. Increasing ventilation flow rate and specific microwave power can improve the drying rate, but the cracking ratio also increases as a negative result. The cracking ratio lower than 10% can be attained for ventilation flow rate lower than 2.0 m3·h−1 or specific microwave energy lower than 0.4 kW·kg−1 in the present experiments.

It is shown that the initial part of the thermal transient in a microcalorimeter contains information on the microwave power conversion efficiency.

The purpose of this study was to investigate the utilization of CO2 in order to obtain polyether-polycarbonate by the co-polymerization of epoxide with CO2 using microwave irradiation. Double metal cyanide containing Zn with Co, Fe(II), Fe(III) and Ni has been utilized as a catalyst for the co-polymerization reaction. The effect of microwave power, catalyst amount and types of catalysts has been studied. The microwaves were found to be successful in the synthesis of polyether-polycarbonate in a shorter reaction time with higher turnover numbers than those in conventional methods.