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The coronavirus disease 2019 (COVID-19) that broke out on December 2019 spread speedily throughout the world, resulting in serious economic problems and increasing the mortality rate. Preceding research illustrated that one of the main routes for the spread of COVID-19 is respiratory aerosol transmission, where the generation of the droplets is created by coughing, sneezing, breathing, and speaking. Therefore, innovative control methods are necessity needed to manage the epidemic. Microwave has been extensively applied to inactivate microorganisms like viruses in many different media. The previous techniques were applied in the laboratory just to virus samples. In this proposal, we use the microwave radiation to inactivate the airborne viruses in the ambient air inside the rooms of hospitals and clinics. The main contribution of this paper is to design a compact antenna array using smart antenna techniques to cover the room with uniform microwave power. It is taken into account that the radiated power is under the standard safety levels.

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.

Carica papaya is a well-known plant with diverse importance to human beings. The efficacy of microwave-assisted extraction (MAE) in the recovery of phenolic compounds from C. papaya leaf was investigated in this study. The MAE process variables were optimized using response surface method; at the optimized conditions, the embedded phenolic compounds in the extract were identified through LC-QTOF-MS analysis. The results showed that the best MAE conditions were: time of irradiation at 3 min; microwave power of 420 W; feed-to-solvent ratio of 1:12 g/mL; and solvent concentration of 56% ethanol/water to achieve 102.59 mg GAE/g d.w. of total phenolic content (TPC). At these conditions, an aggregate of 72 phenolic compounds was tentatively identified. These results infer that MAE as a technique can recover phenolic compounds from C. papaya leaf. Hence, the identified compounds can further be quantified with their respective pharmacological properties in future studies.

The article is devoted to issues related to the development of the electrodynamic system of a relativistic klystron, built on the basis of a linear electron accelerator. It is given a description of a frequency tunable resonator developed by the authors and used for energy extraction of large microwave power.

The article concerns the investigation results of the ø100 mm silicon wafers' influence on the microwave power value fMW=2.45 ± 0.05 GHz in local points on the axis of a reaction-discharge chamber with the volume of about 9000 cm3 of a resonator-type plasmatron. The experiments were carried out in the conditions of the dynamic microwave power redistribution inside a volumetric resonator by using a moving dissector. To register microwave power in the plasma volume, the method of "the active probe" was used. It has been experimentally established that the decrease of distance between the silicon wafers results in the decrease of local microwave power values between them up to 50%. The investigation results of the silicon wafers' influence on the microwave power distribution structure in the gas discharge area indicate the presence of power distribution nonuniformity in the discharge area volume.

The objective of this research is to analyze the microwave power absorption properties of Unsaturated Polyester Resin (UPR) composite reinforced with micro size river-shell with an aim to figure out the new formed composites with the best microwave power absorption scenario. The composites were prepared by using river shell powder in micro-particle size as a filler material with unsaturated polyester composites. Using free-space transmission technique and within the x-band frequency range, the microwave power absorption properties were studied with varied percentages of river shell powder being loaded into the unsaturated polyester composites. River shells were introduced in an 50 microns particle size powder which was mixed in different weight percentages of 5, 10, and 15 % of a 12 cm square shape side length composite sample along with a thickness of 4 mm for each sample. The test specimens were prepared using the pre-mentioned weight amounts after mixing them with the Unsaturated Polyester Resin (UPR) compositions and in accordance with ASTM standard. Number of teste samples are four represented by pure, 5 %, 10 %, and 15 % of river-shell reinforced polyester composites. It has been found that the 5 % is the case when maximum power absorption presents higher levels than other loading percentages. Therefore, such kind of composites can be established under focus in those applications at which their trends is about necessity and importance of microwave power absorption.

The present work is about the production of oil-free potato snacks using successive cycles of microwave heating-vacuum pulses and was therefore called microwave multiflash drying (MWMFD). Drying kinetics and product physical properties were assessed, as well as the influence of blanching (BL) and vacuum impregnation (VI) as pre-treatments before drying. The drying curves presented three periods: a heating period, a high drying rate period promoted by the vacuum pulses, and a falling rate period. The drying time of 400 g of potatoes was approximately 60 min, reducing gradually the microwave power from 800 to 200 W. The vacuum-pulse step changed the material, resulting in a porous and fragile microstructure, characteristic of crispy products, as well resulting in a product surface with a golden yellow color. BL and VI combined was the best pre-treatment for obtaining very crispy oil-free potato snacks. The results of this study indicated MWMFD as a suitable process to produce crispy potato snacks, free of oil, in only 60 min.

The impact of the processing conditions of the edible Undaria pinnatifida brown seaweed on the dehydration and bioactive features was determined using the green microwave hydrodiffusion and gravity technology. For the alga solid phase, the corresponding dehydration and rehydration kinetics, their mathematical modelling, volumetric shrinkage, energy consumption, microscopical and colorimetric properties, phenolic content and antioxidant capacity were analyzed. Results indicated that an increase in microwave power involved a notable drop in the seaweed dehydration time. The shortest dehydration treatment to reach an adequate final moisture content (

The objective of the present study is to improve the biohydrogen production from marine macroalgae (Ulva reticulate) by acidic - hydrogen peroxide (H2O2) induced microwave (AHMW) pretreatment. Higher soluble chemical oxygen demand (SCOD) release of 1450 mg/L and its liquefaction rate of 30.2% was achieved in microwave (MW) pretreatment with treatment time period of 15 mins. Varying concentration of H2O2 from 0.003 to 0.03 g/g TS were used in the optimal microwave power (40%) to enhance the organic release in H2O2 induced microwave pretreatment (HMW). Maximum liquefaction of 33.9% was obtained at the H2O2 concentration of 0.024 g /g TS. The combined HMW pretreatment under acidic (pH 4–6.5) show synergistic effect on organic release. At optimal pH 5, AHMW pretreatment shows the SCOD release of 1850 mg/L with its liquefaction of 38.5% at time of 10 min. Therefore, AHMW pretreatment significantly reduce the treatment time and increase liquefaction when compared to MW and HMW. The maximum biohydrogen production was observed as 92.5 mL H2/g COD in AHMW pretreatment.

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.

The investigation results of a dynamic microwave power fmicrowave = 2, 45 ± 0,05 GHz redistribution in a 9000 cm3 reaction-discharge chamber of a microwave resonator-type plasmatron are presented. In order to redistribute the microwave power, a rotating metallic four-blade L-form dissector placed above the reaction-discharge chamber was used. The microwave power in the local points at the axis of the chamber with plasma and without it was measured applying the "active probe" method. During the experiments the chamber contained silicon plates. Periodical interchange of maximum and minimum microwave power values along the chamber axis was established experimentally. Note, when the dissector was rotating, the range of maximum and minimum "active probe" values dispersion decreased. It has been established that during the dissector rotation the microwave power in the local discharge areas changes with periodic repetition every quarter of revolution.

A thermopile-based microwave power sensor and a double-channel microwave power sensor are compared in order to research the measurement accuracy of microwave power. The relationship of the displacement of MEMS cantilever beam with the measured microwave power is researched, and the reason that the microwave power consumed by the MEMS cantilever cannot be ignored at low power level is explained. The ratio of microwave power consumed by the MEMS cantilever with the microwave frequency is obtained, and the measured results show that the percentage is 51.96%@8GHz, 52.31%@10GHz and 55.11%@12GHz on the average, respectively. There is an important reference value to achieve the accurate microwave power measurement of the double-channel microwave power sensors.

ITER will be equipped with four EC (Electron Cyclotron) Upper Launchers (UL) of 8 MW microwave power each with the aim to counteract plasma instabilities during operation. These launcher antennas will be installed into four upper ports of the ITER vacuum vessel. Beside their functional purpose the port plugs which are the structural system of the launchers, have to provide as much shielding as possible in order to protect adjacent components from neutrons and photons and to minimize the shutdown dose rate in the port interspace and the port cell, being located further back in the ITER Tokamak building. Thus appropriate shielding blocks shall be installed at proper positions inside the plug. In addition several structural components will be dressed up geometrically in order to provide maximum shielding capability. This paper presents the general design of the shielding elements and their technical integration into the EC Upper Launcher.

The sterilization of a small vial using electron cyclotron resonance (ECR) plasma was investigated. The ECR plasma was generated throughout the inside of the small vial, which was sealed with nonwoven fabric, by using magnetic configuration in which the ECR point was located inside the small vial. Moreover, it was demonstrated that the temperature of the small vial was finely controlled by the pulse width and pulse frequency of the pulsed microwave power. A biological indicator (BI), Geobacillus Stearothermophilus, containing 1 × 105 spores present inside the small vial was successfully inactivated in a total treatment time of about 14 min while maintaining treatment temperature of less than 65 °C.

Microwave-assisted hydro-distillation (MAHD) is preferred to traditional extraction methods due to shorter extraction time, the inability of volatile components to be damaged or decomposed which in turn improve the efficiency and quality of essential oils. In this research, we investigated the parameters that affect the extraction of lemongrass oil process by MAHD method and compare with those of hydro-distillation (HD) method. Four parameters were identified which are: raw material size, raw material to water ratio, extraction time and microwave power. The results show that the optimum condition for determining the lemongrass essential oil content is 20 mm in the 90 min extraction time with a microwave power of 450 W at raw material to water ratio of 1:3 (g/mL). When compared to the HD method, we found that the yield lemongrass oil of MAHD method is 0.35% on 90 min and the yield of HD method is 0.2% on 360 min. The quality of oil samples at different extraction method was evaluated by determining their chemical constituents through GC-MS. The highest identified component is Citral with 93.28% for MAHD, while the HD was 83.85%. Therefore, MAHD method is highly efficient and shorten the time needed for the extraction of essential oils.

Papaya (Carica papaya L.) has a diversity of bioactive compounds with recognized antioxidant effects. However, obtaining these compounds presents challenges related to extraction, which must be economical, fast and with high efficiency. In the present study, the performance of microwave irradiation was evaluated to recover extracts with a high content of polyphenols, flavonoids, and an effective antioxidant activity from a mixture of papaya peel and pulp. The factors solid:solvent ratio, microwave power, and ethanol-water mixture were evaluated. The results showed that the maximum content of bioactive compounds was reached after 3 minutes of extraction with the optimum conditions of 340W for power, 23.34% for mixture ethanol:water and 80.60 for solid:solvent ratio. The optimal extract presented a concentration of 1186.39 ± 44.49 mg GAE/100gFW for polyphenols and 43.88 ± 6.94 mg CE/100gFW for flavonoids and antioxidant activity of 3920.48 ± 31.97 mol TE/100gFW, values higher than those reported by other authors. It is confirmed that the application of microwaves in the process of extraction of bioactive compounds reduces time, costs and is efficient to obtain extracts of papaya with an effective antioxidant activity.

High-speed synthesis using microwave technique has attracted considerable intentions among researchers as it provides an efficient time of doing reactions. Modification of liquid natural rubber (LNR) via hydrogenation using of 2,4,6-trimethylbenzenesulfonylhydrazide (MSH) produced hydrogenated liquid natural rubber (HLNR). The results showed that microwave-assisted hydrogenation of LNR was experimentally found to give expected product in a short time (10–20 min). The structure of products was characterized by Fourier-transform infrared (FTIR) and the percentage of hydrogenation was determined from the 1H-NMR spectrum. The highest hydrogenation percentage of HLNR for hydrogenation of LNR by microwave heating were obtained; an LNR hydrogenation percentage of 41.18% at a MSH:LNR weight ratio of 1.5:1, a microwave power of 600 W and a reaction time of 20 min. Diimide molecules have been generated more quickly at microwave frequencies and yield HLNR in a shorter time compared to reflux heating method.

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.

The investigation of injection locking of cooker magnetron by a solid-state microwave power source is reported. Experimental results show that a 2.45 GHz cooker magnetron can be locked in continuou...

Eggplant was dried under different microwave power and sample thicknesses to study their effect on quality properties (color parameters (L, a and ∆E), browning index and firmness) of eggplant slices. Eggplant slices were dried by microwave using microwave powers (450 W, 630 W and 810 W) and 0.5, 1, 1.5 and 2 cm of eggplant thicknesses. The results showed that, the higher L value was 43.23 occurred when drying eggplant slices with thickness 0.5 cm and microwave oven power 450 watt at 2.29% moisture content before burning. The higher a value was 13.66 occurred when drying eggplant slices with thickness 2 cm and microwave oven power 810 watt at 2.07 % moisture content before burning. The ∆E varied from 5.54 to 33.09 at 0.5 cm of eggplant slices thicknesses and 450 Watt of microwave power. The higher (BI) value was 573.98 occurred when drying eggplant slices with thickness 2 cm and microwave oven power 810 watt. The higher and the lower final firmness value were 41.3 N and 28.45 N occurred when drying eggplant slices at thickness 0.5 and 2 cm and microwave oven power 450 watt respectively.

The microwave vacuum drying (MWVC) and combined microwave-hot air drying (MWHA) under step-down microwave power input were proposed for drying durian chips. These techniques were compared with multi-stage hybrid drying (MSH) and hot air drying (HA) on drying kinetics, specific energy consumption (SEC) of the drying process and qualities of the dried durian chips in terms of colour, shrinkage percentage, texture profile, water activity, and microstructure. Some properties were also compared with those of commercially-fried durian chips. The results showed that the drying rates of step-down MWHA and MWVC increased in line with increases in the microwave power used during the first stage of drying and with decreases in the vacuum pressure used in the step-down MWVC. These enhanced drying rates led to short drying times and resulted in less SEC in both heat and electricity. The durian chips dried by the step-down MWVC and MWHA had higher values of lightness, crispness, large pore size and void area fraction, but lower values in terms of hardness and shrinkage percentage than those dried by the MSH and HA. Increasing the microwave power in the step-down MWVC and MWHA, and the MSH gave the dried durian chips higher values of lightness, crispness, large pore size and void area fraction, but lower values of hardness and shrinkage percentage. The step-down MWHA is recommended for drying durian chips due to the highest drying rate and the most overall preferential qualities of dried durian chips, although less than the commercially-fried durian chips.

Syafutri et al, 2019. Physicochemical Properties of Colorant from Water Hyacinth Flower ( Eichhornia crassipes ) Extracted by Microwave Assisted Extraction ( MAE ) Method . JLSO 8(1):94-106. The objective of this research was to determine the effect of oven microwave power and extraction time on color intensity, anthocyanin stability, and antioxidant activity of colorant from water hyacinth flower ( Eichhornia crassipes ) extracted by microwave assisted extraction (MAE) method. The research was conducted at Agricultural Product Chemical Laboratory, Agricultural Technology Department, Faculty of Agriculture, Sriwijaya University. The experiment used a Factorial Completely Randomized Design with two factors and each treatment was repeated three times. The first factor was oven microwave power (100 watts and 300 watts) and the second factor was extraction time in oven microwave (1 minute, 2 minutes, and 3 minutes). The parameters were color intensity, anthocyanin stability, and antioxidant activity. The results showed that the oven microwave power and extraction time had significant effects on color intensity and antioxidant activity. The increasing of oven microwave power and extraction time increased a* value and antioxidant activity, and decreased b * value, significantly. The result also showed that the anthocyanin compounds was not stable with heating up to 105°C.

Pulse-spouted microwave freeze drying (PSMFD) used for Chinese yam cubes was evaluated at three microwave power levels (400, 600, and 800 W). The drying characteristics, energy consumption, and qua...

To realize microwave power traceability, we apply a newly developed calibration technique for measuring the correction factor of a calorimeter with a vector network analyzer in the WR-15 frequency band. The wave-parameter approach is used to formulate analytic expressions for the correction factor and effective efficiency. This allows us to systematically track the uncertainty with correlation along an unbroken path. Measurement results are consistent with what was previously obtained by use of the conventional method.

Conjugated linoleic acid (CLA) is commercially produced by alkali isomerization of linoleic acid (LNA). However, this method constitutes a relatively high content of undesirable CLA isomers. In present study, microwave-assisted and ultrasound-assisted alkali isomerization techniques were applied for production of CLA as an alternative to traditional alkali isomerization. This study was aimed to evaluate the isomerization degree of LNA, by using various process conditions such as microwave power, ultrasound amplitude, and their reaction times. The best conditions for LNA isomerization were a microwave power of 700 W and a reaction time of 6 h for microwave-assisted alkali isomerization and an ultrasound amplitude of 100% and a reaction time of 6 h for ultrasound-assisted alkali isomerization. Under determined conditions, microwave-assisted alkali isomerization (97.21%) resulted in a higher isomerization degree compared to ultrasound-assisted alkali isomerization (76.98%) while the content of undesirable CLA isomers in ultrasound-assisted alkali isomerization (0.62%) was lower than that of microwave-assisted alkali isomerization (1.87%). This study showed that application of the both techniques resulted in equal amounts of desirable CLA isomers. The content of desirable CLA isomers was 47.09% cis-9, trans-11 and 48.25% trans-10, cis-12 for microwave-assisted alkali isomerization and 36.34% cis-9, trans-11 and 40.02% trans-10, cis-12 for ultrasound-assisted alkali isomerization. © 2019 AOCS

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

In this paper, a novel microwave power detection system based on Schottky diode is constructed in order to measure microwave power in the LTE-band (1.8~2.7 GHz). The proposed detection system is consisted of three modules: a collecting module, a measuring module, and a processing module. Among them, a microwave power detection circuit based on Schottky diode is developed to realize the high-quality conversion of microwave power signal to voltage signal. The experimental results reveal that the presented system has good linearity. In the range of 1.8~2.7 GHz, the incident microwave power is increased from 1 uW to 50 mW, and the sensitivity of the detection system is 1.86 mV/uW at 2.0 GHz, 1.61 mV/uW at 2.3 GHz, and 1.2 mV/uW at 2.6 GHz, which is much better than other microwave power sensors. Therefore, the microwave power detection system based on Schottky diode provides an effective solution for microwave power detection in the LTE-band.

s Sesamum indicum is an important commodity plant that is highly valued for its distinctive flavor, nutritional and medicinal function. The polyphenolic constituents in sesame leaves is responsible for its numerous medicinal and nutritional properties. Unfortunately, the extraction of bioactive constituents and their inherent physicochemical characterization is rarely investigated using optimum condition of extraction. In this study, sesame leaves were extracted and optimized using microwave radiation and orthogonal design, respectively. The result from the parametric study gave an optimum condition at 2 min of microwave radiation, 600 W of microwave power, and 80% of ethanol concentration. Under this condition, the optimal yield of the phenolic was 132 (mg GAE/g d.w.). The micro-pores and cavities on the scanning electron micrograph of the residue confirmed the morphological changes as a result of the applied electromagnetic radiation. The appearance of four phenolic functional groups indicated the potential of the extracts for medicinal and nutritional purposes. Moreover, the overall in-vitro free-radical biological assays further confirmed that the phenolic compounds present in the extract were markedly responsible for myriads of medicinal functions. The study, therefore, presented a better understanding of parameters effects on the total recovery of polyphenolic constituents from S. indicum leaves with their free-radical scavenging physiochemical characteristic which could form a basis for future applications in pharmaceutical industries.

In order to improve the utilization of tea seed, microwave/ultrasonic assisted extraction (MUAE) was firstly applied for the extraction of tea seed oil (TSO). The factors with significant effects on oil yield were screened by Plackett-Burman design and then optimized by Box-Behnken design. The oil yield of 31.52% was obtained under optimum extraction conditions of microwave power 440 W, ultrasonic power 550 W, extraction time 38 min, solvent to material ratio 8 mL/g, extraction temperature 70 ℃ and particle size

This study investigated the effect of air temperature, microwave power, and pomace thickness on the drying kinetics and quality of dried carrot pomace. The study established that the drying of carrot pomace occurs in the falling rate period, suggesting that drying was driven by molecular diffusion. The microwave-drying moisture diffusivity increased with microwave power and ranged between 1.57×10–8 and 2.61×10–8 m2/s. As regards convective air-drying, the moisture diffusivity values were between 3.38×10–10 and 8.27×10–10 m2/s. The microwave powerto-mass activation energy was 15.079 W/g for 5 mm, 7.599 W/g for 10 mm and 9.542 W/g for 15 mm dried samples. Meanwhile, the temperature-dependent activation energy for carrot pomace was found to be 27.637 kJ/mol for 5 mm, 17.92 kJ/mol for 10 mm and 38.76 kJ/mol for 15 mm thickness pomace. Generally, drying time decreased with increasing microwave power or air temperature. The ascorbic acid content of the fresh carrot pomace reduced after both microwave and convective air-drying. However, microwave power, and sample thickness had significant effect on the β-carotene content of dried products but air temperature did not have a significant effect. The effect of temperature and sample thickness on brown pigment formation was substantial with air temperature compared to microwave. The study has demonstrated that microwave drying, compared to conventional drying, enhances moisture removal, drying time, and preservation of carotenoids and ascorbic acid. Therefore, microwave drying can be considered as an alternative method for obtaining quality dried carrot pomace.

The aim of this work was to apply the ultrasound-assisted or ultrasound combined microwave vacuum frying (UMVF) technology in frying of foods to reduce frying time and improve color and crispness. Apple slices were used as model material for frying. Two microwave power levels (800 W and 1000 W) were used at fixed ultrasound power and frequency of 600 W and 28 kHz, respectively. Frying was carried out for 16 min. The effect of UMVF on residual moisture content, oil uptake, textural crispness and color parameters was measured and analyzed. The odor profile of the fried slices was measured and analyzed using electronic nose (E-nose). The application of UMVF technology significantly increased the moisture evaporation rate, shortened the frying time, increased the textural crispiness and produced more desirable yellow color compared to microwave vacuum frying (MVF) technology. The ultimate oil uptake in UMVF products was similar to that in MVF products. The UMVF produced less Maillard reaction products compared to MVF. Therefore, the UMVF technology is more effective than MVF and can be preferably used in frying foods.

Microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE) have been studied to extract natural phenolic compounds from lime peel wastes. A response surface methodology with a three-level and three-factor Box-Behnken design was used to predict the optimal conditions of each extraction parameter based on the total phenolic contents, antioxidant activities and the half maximal inhibitory concentration. The results showed that the optimal predicted MAE was obtained at 55% ethanol concentration, 140 W microwave power for 45 s with 8 repeats of the extraction step. Meanwhile, the optimal predicted UAE was at 55% ethanol concentration, 38% amplitude and 4 min extraction time. UAE was the more effective method to extract the total phenolics (54.4 mg GAE/g) with high antioxidant activity and saving of time of 33% compared with MAE. Therefore, the natural phenolic extract from lime peel waste might be available as a source of active and functional compounds for pharmaceutical and food products.

We report remarkably high, up to 100-fold, signal enhancements in (19)F dynamic nuclear polarization (DNP) magic angle spinning (MAS) spectra at 14.1 T on HIV-1 CA capsid protein assemblies. These enhancements correspond to absolute sensitivity ratios of 12–29 and are of similar magnitude as seen for (1)H signals in the same samples. At MAS frequencies above 20 kHz, it was possible to record 2D (19)F-(13)C HETCOR spectra, which contain long-range intra- and intermolecular correlations. Such correlations provide unique distance restraints, inaccessible in conventional experiments without DNP for protein structure determination. Furthermore, systematic quantification of the DNP enhancements as a function of biradical concentration, MAS frequency, temperature, and microwave power is reported. Our work establishes the power of DNP-enhanced (19)F MAS NMR spectroscopy for structural characterization of HIV-1 CA assemblies and this approach is anticipated to be applicable to a wide range of large biomolecular systems.

Phenolic compounds were extracted from pistachio hull using microwave-assisted solvent extraction (MASE). The effects of four parameters, microwave power, extraction time, solvent to sample...

Extraction of pectin from pomelo peel was performed using water, acid and alkaline solutions with a microwave power of 1100 W for 2 min, and yield and structural/chemical characteristics of the extracted pectins were investigated. Extraction of pectin with water gave the lowest yield (6.5%, dry weight basis). The water-extracted pectin contained the highest amount of neutral sugar (29.5%), while equivalent molecular weight (MWeq) and degree of methylation (DM) were 43 kDa and 29.7%, respectively. Extraction of pectin with HCl solutions at concentrations of 25, 50, 100 and 200 mM resulted in a significant increase of pectin yields (12.1–20.5%) and pectins with high amount of galacturonic acid (83.3–85.6%). The MWeq and DM of the acid-extracted pectins ranged from 171 to 368 kDa and 53.9–82.5%, respectively. Compared to the acid, extraction with NaOH solutions at the same concentrations provided higher yields (13.9–24.2%), smaller size (142–187 kDa) and lower DM (

Large capacity in extraction using the microwave hydrodistillation method is always a challenge to do. The biggest obstacle in this method is the limitations of microwaves penetrating the material. Besides that, the high heat produced due to molecular heating simultaneously causes some components to degrade and reduce the quality of essential oils. The purpose of this research is to study the effect of the ratio of the sample plant (Cymbopogonnardus) to the solvent (F/S = 0.08, 0.16, 0.24 g/mL), as well as the ratio of volume distiller to volume microwave cavity (D/M = 0,04, 0,08 v/v) to the yield and quality of Citronella Oil produced. The experimental lead to the conclusion that the ratio of the sample plant to the solvent (F/S) of 0.24 g/ mL is the maximum for extraction of Citronella Oil. The ratio of volume distiller to volume microwave cavity (D/M) 0,08 v/v provides a higher yield compared to (D/M) 0,04 v/v with a longer extraction time. The qualitative analysis by GC-MS shows that the Citronella is the main component of Citronella Oil. The composition showed significant differences in the essential oil content of different ratio of volume distiller to volume microwave cavity (D/M). The ratio volume distiller to volume microwave cavity (D/M) 0,04 v/v gave 21 component with the highest Citronella percentage (40.54%). Compared to (D/M) 0,08 v/v gave 27 component with the Citronella percentage (18.64%). The results showed that different volume of distillers showed different yields and components.

The effects of microwave cooking on the changes of physical properties, protein denaturation, microstructure and volatiles of yak meat were investigated. Various microwave power settings were used for cooking the yak longissimus meats, and SDS-PAGE, cooking loss, colour difference, shear force, microstructure and volatile flavour compounds of longissimus muscle were evaluated. Cooking losses (37.03–45.92%) and shear forces (257.20–315.57 N) in microwave heated meats were higher and lower, respectively, than these in boiled meats (p

In this research, the effects of intermittent drying variables on some quality properties of parboiled rice were investigated, then a mathematical model was applied to predict the value of quality features non-destructively using response surface methodology (RSM). The intermittent drying variables consisted of hot air temperature (40, 50 and 60?C), radiation intensity (0.21, 0.31 and 0.41 W/cm2) and microwave power (100, 200 and 300 W). The intermittent drying was performed at two stages with a tempering time between drying steps using a hybrid drying of hot air?infrared radiation and microwave drying at the first stage and second stage, respectively. According to RSM results, the effect of drying variables on the quality properties of parboiled rice were significant (p < 0.01). Also, the best mathematical model for prediction of quality properties of samples was the quadratic equation (R2 = 0.96-0.98). The HRY (61.8-73.2%), hardness (118.63-215.27 N) and color value (17.28-19.22) increased, while the lightness (64.17-59.51) decreased during drying. RSM can be able to predict the optimization parameters for the best quality properties (i.e., HRY = 72.42%, lightness = 59.47, color value = 19.25 and hardness = 213.91 N) based on temperature of 60?C, radiation of 0.41 W/cm2 and power of 300 W.

Microwave (MW) blanching (MWB) of vegetables has been applied in food industry as alternative to conventional treatment. Therefore, this study was aimed to evaluate the efficacy of MWB in terms of peroxidase (POD) inactivation, by applying various process conditions (MW power and process time) to different vegetables (potatoes, savoy and white cabbage), mimicking the most common geometric shapes (cylindrical, cubed, parallelepiped and slabbed). In all 3-D shapes, POD inactivation was initially achieved at the core of sample and gradually extended toward the periphery with the increase of process intensity. However, MWB appeared to be not suitable for reaching the temperature level required for the POD irreversible inactivation on the surface of vegetables, neither in 3-D nor in slabbed shape. The optimal blanching conditions (POD residual activity

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.