Effect Of Microwave Irradiation Research Articles

Mechanistic effects of microwave radiation on pupal emergence in the leafminer fly, Liriomyza trifolii.

Liriomyza trifolii is a significant pest of vegetable and ornamental crops across the globe. Microwave radiation has been used for controlling pests in stored products; however, there are few reports on the use of microwaves for eradicating agricultural pests such as L. trifolii, and its effects on pests at the molecular level is unclear. In this study, we show that microwave radiation inhibited the emergence of L. trifolii pupae. Transcriptomic studies of L. trifolii indicated significant enrichment of differentially expressed genes (DEGs) in 'post-translational modification, protein turnover, chaperones', 'sensory perception of pain/transcription repressor complex/zinc ion binding' and 'insulin signaling pathway' when analyzed with the Clusters of Orthologous Groups, Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes databases, respectively. The top DEGs were related to reproduction, immunity and development and were significantly expressed after microwave radiation. Interestingly, there was no significant difference in the expression of genes encoding heat shock proteins or antioxidant enzymes in L. trifolii treated with microwave radiation as compared to the untreated control. The expression of DEGs encoding cuticular protein and protein takeout were silenced by RNA interference, and the results showed that knockdown of these two DEGs reduced the survival of L. trifolii exposed to microwave radiation. The results of this study help elucidate the molecular response of L. trifolii exposed to microwave radiation and provide novel ideas for control.

Mixed‐mode I/II fracture properties and failure characteristics of microwave‐irradiated basalt: An experimental study

AbstractThe notched semicircular bending samples with different microwave irradiations were subjected to 3‐point bending fracture tests under mixed‐mode I/II loading to investigate the effects of microwave irradiation on the fracture characteristics of basalt. Influences of the irradiation duration on the temperature, P‐wave velocity, and mixed‐mode I/II fracture characteristics under 2 kW power were studied. The acoustic emission device was utilized to monitor the acoustic emission signals during the destruction process. The P‐wave velocity and equivalent fracture toughness are weakened by microwave irradiation, but the ductility of basalt is enhanced by microwave irradiation. The microscopic characteristics of the treated basalts were observed by scanning electron microscope. Microwave irradiation aggravated the creation and propagation of microcracks and pores. The study of the influence of microwave irradiation on mixed‐mode I/II fracture characteristics of rock provides effective theoretical support for microwave‐assisted rock fragmentation.

Using molecular dynamics simulations to study the non-thermal effects of microwave radiation on the mechanism of char gasification

Studying the chemical effects of alternating electric fields on char gasification is key to exploring the non-thermal effects of microwaves on the reaction mechanism. The gasification mechanism of char in the presence of an electric field was explored through molecular dynamics (MD) simulations and quantum chemical calculations. The results show that the promotion effect of 0.02 V/Å alternating electric field on the gasification reaction rate of char is about 8 times that of non-electric field, and the square wave electric field and static electric field are 6.79 times and 5.39 times respectively, this effect increases exponentially as the field intensity increases. Interestingly, the use of alternating electric fields showed, for the first time, that the changes in the electric field intensity and direction also have a significant effect. In terms of the adsorption process during gasification, the electric field promotes the formation of O and OH free radicals (about 5 times of no electric field) and increases the polarity of the char edge, both of which are conducive to adsorption. The electric field can weaken the curling of char macromolecules and expose more active carbon sites, thus increasing the overall reaction rate. For the desorption process during gasification, the presence of the electric field promotes the deformation and tear of char, which destroys its aromaticity, loosening the carbon-oxygen compounds at the carbon edge, which facilitates the desorption of CO, the desorption rate is about 10 times that of non-electric field system. Further, the change in direction of the electric field also promotes the desorption process. The results from this study suggest that the remarkable effects of alternating electric fields on char molecules can have an impact on the field of solid fuel gasification.

MOF-derived CoNC@rGO/amine-rich@rGO/fluorinated-epoxy nanocomposites with EMI shielding, mechanical robustness, superamphiphobicity and long-term anticorrosion properties

Along with the rapid development of electronic devices and communication systems, electromagnetic (EM) radiation pollution has become an increasingly serious problem. However, it is greatly challenging to achieve absorption-dominated electromagnetic interference (EMI) shielding and robust multifunctional simultaneously. In this work, we synthesize zeolitic imidazolate framework (ZIF67)-derived CoNC@reduced graphene oxide (rGO) and amine-rich surface rGO (NH2@rGO), and subsequently fabricate NH2-CoNC@rGO-fluorinated epoxy (FEP) nanocomposites by the microwave irradiation strategy, and this is the first time to obtain composite combining excellent EMI shielding, mechanical robustness, superamphiphobicity and long-term anticorrosion properties. Wherein, 3-(perfluoro-n-octyl) propenoxide (PFOP) provides the perfluorinated long chains, which improves both mechanical properties via internal antiplasticization effect, and the dispersity and loading of nanofiller via CF⋯HN/π interactions; 4,4′-hexafluoroisopropylidenediphenol diglycidyl ether (FAEP) increases the compatibility and mechanical robustness; NH2@rGO provides the good interfacial bonding, dielectric attenuation and anode protection; CoNC@rGO endows suitable magnetic and dipolar relaxation loss, micro/nanostructures and cathodic protection. Remarkably, the optimized nanocomposite exhibits satisfied tensile and impact strength (64.4 MPa, 33.7 kJ/m2), EMI shielding properties (56 dB), thermal conductivity (1.13 W·m−1·K−1), superhydrophobicity (154°) and superoleophobicity (151°), self-cleaning, good chemical and mechanical robustness, Joule heating capacity and long-term anticorrosion (30 d). Furthermore, the microwave irradiation effect, multiple EMI shielding and anti-corrosion mechanism have been discussed in detail. This study provides an efficient guideline for designing multicomponent and multidimensional epoxy nanocomposite with EMI shielding and robust multifunctional property in aerospace, underwater equipment, electronic devices and precision construction protection.

Kinetic study of multiphase reactions under microwave irradiation: A mini-review

Microwave (MW) heating is rapid, selective, and volumetric, and it is a compelling non-conventional heating approach for driving chemical reactions. The effect of MW irradiation on the kinetics of thermal/catalytic reactions is still under debate. A group of researchers reported that the effect of MW heating on reaction kinetics is highlighted through the non-thermal effects of MWs on kinetic parameters and reaction mechanisms in addition to the thermal effect. However, another group attributed the observations to the thermal effect only. In the present work, we summarized and critically synthesized available information in the literature on the subject. It can be concluded that MW heating has solely the thermal effect on gas-solid reactions, and the variations of kinetic parameters are related to the direct and indirect impacts of that. Temperature measurement limitations, physical structure variation, and non-uniform temperature distribution are the primary sources of the discrepancy in previous studies. In ionic liquid-solid reactions, the presence of electromagnetic fields can affect the movement of ions/polar molecules which can be considered a non-thermal effect of MWs. However, the effect of MW absorption by solid/catalyst, and the formation of hot spots must be taken into account to avoid potential discrepancy. Therefore, further theoretical/experimental studies are required to clarify the effect of MWs on liquid-solid reactions. In addition, developing reliable temperature measurement methods and isothermal reaction domain are required for an accurate kinetic study during MW irradiation.

Green approach for the recovery of secondary metabolites from the roots of Nardostachys Jatamansi (D. Don) DC using microwave radiations: Process optimization and anti-alzheimer evaluation

Nardostachys jatamansi (D. Don) DC is a highly valued medicinal herb that has been used in traditional medicinal systems for its remedial effects. Owing to the over-exploitation and unethical trade of N. jatamansi, the accelerating global demand of herbal products from this plant cannot be satisfied by the conventional extraction approach. In view of the progressive demand and incredible biological potential of herb, the present research was designed to optimize various extraction parameters for microwave-assisted extraction (MAE). The extracts obtained from the traditional and green approach were also assessed for the recovery of secondary metabolites and anti-Alzheimer's potential. Various parameters like microwave power, temperature, and time of irradiation were optimized for MAE using Box Behkhen Design (BBD) The scanning electron microscopy of different plant samples was also done to observe the effect of microwave radiations. Further, the metabolite profiling of different extracts was also done by gas chromatography-mass spectrometry (GC-MS) analysis. Also the different behavioral and biochemical parameters along with acetylcholinesterase (AChE) inhibitory potential were assessed to evaluate the anti-Alzheimer's potential. Optimized parameters for MAE were found to be as microwave power 187.04 W, temperature 90°C, and irradiation time 20 min. The extract yield in MAE was significantly enhanced as compared to the conventional method. Also, the total phenolic content and total flavonoid content (TFC) were improved pointedly from 32.13 ± 0.55 to 72.83 ± 1.1 mg of GAE/g of extract and 21.7 ± 0.85 to 39.21 ± 0.7 mg of RUE/g of extract respectively. Later, the GC-MS analysis of various extracts confirmed the enhancement in the concentration of various sesquiterpenes like jatamansone, spirojatamol, valerenal, valeric acid, globulol, nootkatone and steroidal compounds such as sitosterol, ergosterol, stigmastanone, etc. in the optimized extract. A significant improvement in anti-Alzheimer's potential was also observed owing to the better concentration of secondary metabolites in the optimized microwave extract. From the current findings, it could be concluded that the MAE could be a successful and green alternative for the extraction and recovery of secondary metabolites from the selected medicinal herb.

Effect of Microwave Irradiation at Different Stages of Manufacturing Unsaturated Polyester Nanocomposite.

The possibility of using microwave radiation at various stages of obtaining an unsaturated polyester composite modified with carbon nanotubes was studied. The optimal content of MWCNTs in the system was experimentally selected, having the best effect on the strength of the composite. The effect of the microwave field on the properties of a polyester composite during the microwave treatment of an oligomer, a polymerized composite, and MWCNTs before their addition into the oligomer was studied. The processes of the structure formation, the structure of the composite, the effect of the microwave radiation on MWCNTs, and the thermal stability of the resulting composites were considered.

Exposure of Food Samples to Pulsed Microwave Radiation to Increase their Microbiological Safety and Shelf Life

The aim of the study was to increase the efficiency of decontamination of biological material and media (by the example of food products) by pulsed (non-thermal) radio emission and asses the prospects of its application in medicine and biology.Materials and methods. To achieve the goal an experimental setup has been designed, manufactured and tested, which makes it possible to study the process of exposure of biological materials and media to pulsed (non-thermal) radio emission, in particular, by the example of food products. The basis of the method is optimum control of the electro-physical parameters of the irradiating radio signal, depending on the type of the irradiated object. We used pulsed magnetrons with operating frequency of (2.45±0.05) GHz, authorized for bio-medical research, generating pulsed radiation with an adjustable power within the range of 0.1...10 kW. The pulse repetition rate with a duty cycle of 500...10000 is 0.1...5 kHz. The setup has an operating chamber into which the test sample is placed, as well as additional elements of magnetron protection and measuring the parameters of the microwave power incident on biological object.Results and discussion. The setup has been successfully used to irradiate various food samples with pathogenic micro flora (Salmonella spp. etc.) with pulsed microwave radiation. In particular, as shown by the studies, the arithmetic mean number of pathogenic bacteria in the irradiated samples of minced meat decreased by 27.5 times after 28 days of storage as compared to the control group of non-irradiated samples. Preliminary conducted experiments in the field of investigating the effect of microwave radiation on the process of cell division and other aspects of electromagnetic field influence on pathological microorganisms confirm the prospects and the expediency of continuing the ongoing studies in medicine and biology.

Combined effects of microwave irradiation and water cooling on the deformation and failure behaviours of CSTBD granite

The low cutting rate and high cutting tool wear rate in hard rock tunnel excavation by a tunnel boring machine (TBM) are critical problems. By integrating microwave technology with water cooling into the TBM cutterhead, microwave-assisted mechanical rock breaking provides a promising solution. To reveal the deformation and failure behaviours of hard rocks after microwave heating and water cooling, this work experimentally conducted a series of tests on cracked straight-through Brazilian disc (CSTBD) granite specimens, where the crack angle was set to 0, 30, 60, and 90° and the microwave heating duration was set to 0.5, 1, 3, 5, and 7 min. During the experiment, digital image correlation (DIC) technology was employed to measure the deformation and failure process. The results show that microwave heating and water-based cooling facilitate the failure of CSTBD granite. The mode-Ⅰ fracture toughness linearly decreases with heating duration for pure tensile failure (crack angle: θ=0°), while it linearly increases with heating duration at other crack angles (30°, 60°, and 90°). The mode-Ⅱ fracture toughness linearly decreases with heating duration in the crack angle range of 0° to 90°. The mode-Ⅰ fracture toughness linearly decreases with the crack angle. The mode-Ⅱ fracture toughness increases with a crack angle of <24° and decreases in the crack angle range of 24° to 90°. The failure patterns are divided into five categories by different crack angles: pure tensile failure (θ = 0°), tensile-shear mixed failure (0° <θ < 24°), shear failure (θ = 24°), compressive-shear mixed failure (24° <θ < 90°), and compressive failure (θ = 90°). The reasons for the main and second cracks during the failure process are revealed. The experimental results have significant implications for microwave-assisted mechanical rock breaking.

Effects of microwave radiation on dynamic compressive properties of basalt

The dynamic mechanical properties of basalt affected by microwave were investigated by performing dynamic compressive tests using the SHPB system. Meanwhile, the thermal damage of the treated basalt was characterized by ultrasonic non-destructive testing and nuclear magnetic resonance technology. The results show that with the increase of microwave power and exposure time, the P-wave velocity, dynamic compressive strength and elastic modulus decrease continuously, and the dynamic failure mode tends to be a more complex fracturing. The increase in microwave power and exposure time can enhance the temperature difference and transfer coefficient among minerals, hence intensifying the rock damage induced by thermal shock.

Effect of Microwave Radiation on the Development of a Porous Aluminum Carrier of the Active Mass of Catalysts in Heterogeneous Catalytic Reactions

In this study, we prepared a fine-grained, aluminum-reinforced alumina support matrix of the active mass of catalysts, which showed activity in heterogeneous catalytic reactions stimulated by electromagnetic radiation in the microwave range. The support absorbed microwave radiation of 2.45 GHz. We compared the textural characteristics of samples of Аl/Аl&lt;sub&gt;2&lt;/sub&gt;О&lt;sub&gt;3 &lt;/sub&gt;supports obtained by conventional heat treatment to those synthesized by heat treatment in a microwave field. We found several advantages of heat treating potential supports of the active mass by using microwave radiation. Using the examples of joint deep oxidation of n-butane and carbon monoxide, dealkylation of toluene with water vapor into benzene, and acidylation of diethyl amine with m-toluic acid, we found that after exposure to microwave radiation, the fine-grained aluminum powder-reinforced Аl/Аl&lt;sub&gt;2&lt;/sub&gt;О&lt;sub&gt;3&lt;/sub&gt; support can be used for preparing catalysts that can be used in reactions stimulated by a microwave electromagnetic field.

SIMULATION OF DIFFUSION-DRIFF PROCESSES IN THE ELECTRON-HOLE PLASMA OF THE P-I-N-DIODES ACTIVE REGION UNDER THE CONDITIONS OF A MW PENETRATING IN THE PLASMA BY THE PERTURBATION THEORY METHODS

Background. The problem of developing tools for mathematical modeling of the state of electron-hole plasma in the p-i-n structures active region under the influence of an additional factor - a powerful microwave electromagnetic field is considered. The task is important for specialists in the field of microwave electronics, since p-i-n structures are used, in particular, for switching powerful electromagnetic fields and as protective devices for the input paths of radio engineering systems.&#x0D; Objective. It consists in developing a methodology for modeling the electron-hole plasma concentration distribution in the p-i-n- diodes active region taking into account the effect on the dynamics of charge carriers of microwave radiation penetrating into the active region and developing asymptotic methods for solving the corresponding singularly perturbed nonlinear problems.&#x0D; Methods. Achieving the goal is ensured by the use of boundary layer method, complex amplitudes method and classical analytic-numerical methods for solving boundary value problems for systems of ordinary differential equations.&#x0D; Results. A generalized mathematical model of the electron-hole plasma stationary state in the p-i-n diodes active region in the hydrodynamic approximation, which takes into account the effect of microwave radiation on processes in the plasma, is proposed. The model basis is a nonlinear singularly perturbed boundary value problem for the system of electron-hole currents continuity equations and the Poisson. The model boundary value problem is reduced to a recurrent sequence of linear boundary value problems. Solutions of the stated problem are found in the form of asymptotic series containing stationary and non-stationary components. A feature of the proposed mathematical model is that it reflects the effect of detecting an electromagnetic microwave TE-like wave on the charge carrier concentration distribution inhomogeneity in the p-i-n-diode active region.&#x0D; Conclusions. The methodology for modeling the electron-hole plasma stationary state in the p-i-n-diodes active region taking into account the effect on the charge carriers dynamics of microwave radiation penetrating into the active region has been developed.&#x0D;

Physical Differences between Man-Made and Cosmic Microwave Electromagnetic Radiation and Their Exposure Limits, and Radiofrequencies as Generators of Biotoxic Free Radicals

The critical arguments for radiofrequency radiation exposure limits are currently based on the principle that radio frequencies (RF) and electromagnetic fields (EMFs) are non-ionising, and their exposure limits are even 100-fold lower than those emitted from the Sun in the whole RF-EMF spectrum. Nonetheless, this argument has been challenged by numerous experimental and theoretical studies on the diverse biological effects of RF-EMF at much lower power density (W/m2) levels than today’s exposing limits. On the other hand, less attention has been given to counterarguments based on the differences in the physics concepts underlying man-made versus natural electromagnetic radiation (EMR) and on the fact that man’s biology has been adapted to the natural EMR levels reaching Earth’s surface at single EMF wavelengths, which are the natural limits of man’s exposure to EMFs. The article highlights the main points of interaction of natural and man-made radiation with biomatter and reveals the physical theoretical background that explains the effects of man-made microwave radiation on biological matter. Moreover, the article extends its analysis on experimental quantum effects, establishing the “ionising-like” effects of man-made microwave radiation on biological matter.

Effect of time and wattage power levels of microwave treatment on the microbial quality and safety of bovine raw milk

Raw milk is sterile when secreted by healthy cows, however it is contaminated with different microorganisms and Streptococci commonly present in the milk ducts as well as teats. The bacterial count in raw milk ranges from a few hundred to several thousand per mL of milk, however it is harmful to human health under unpasteurized condition. Milk sanitization methods rely on the principle of preventing the growth and development of microbes and thus maintaining their nutritional quality. This study was carried out to investigate the effect of microwave radiation on the microbial quality and safety of bovine raw milk. To do so, the effect of microwaves at a frequency of 35 KH and powers of 180, 300 and 850 W for 0, 30, 60 and 90 s on the destruction of pathogens and reduction of microbial load of milk (total bacterial count, coliforms, Escherichia coli, Staphylococcus aureus, molds and yeasts) was investigated. The results showed that microwave treatment had a significant effect on reducing the number of microorganisms in milk samples (p&lt;0.0) with the power of 850 W being the most effective power for reducing the number of S. aureus, coliforms, molds, yeasts as well as total bacterial count. Faster heating with higher energy efficiency is the main advantage of the microwave process for foods. In fact, the microwave method can be a potential and effective method for decreasing the microbial load of raw milk.

Effects of high-power microwave irradiation on tar-rich coal for realising in situ pyrolysis, fragmentation, and low-carbon utilisation of tar-rich coal

Tar-rich coal was directly combusted during power generation, resulting in a huge waste of precious oil resources and a large amount of carbon emissions . The idea of intelligent unmanned mining machine (IUMM) for in-situ fluidised mining and conversion of tar-rich coal was proposed to solve the problems of traditional mining and utilisation methods, realise efficient utilisation of tar-rich coal, and achieve net-zero CO 2 emission. A key technology of IUMM is the pyrolysis and fragmentation of tar-rich coal by high-power microwave irradiation . In this study, we carried out experiments on the strength and microstructural changes of tar-rich coal under different microwave irradiation conditions using the high-power microwave irradiation testing system to explore the effects of microwave irradiation on tar-rich coal and provide a reference for the design of IUMM. The X-ray computed tomography was employed to observe and characterize the initiation, growth, connection, and spatial distribution of internal fractures of tar-rich coal under different microwave irradiation conditions. The quantitative relationship between the strength characteristics of tar-rich coal and microwave irradiation conditions was established. The results show that under a fixed microwave power or irradiation time, the overflow rate of coal gas and tar is linearly positively correlated with microwave energy E , and both the uniaxial compressive strength and brittleness of tar-rich coal have piecewise linear negative correlation with E . With the increase of E , the internal fractures grow and connect more, which are synchronised with the decrease of the uniaxial compressive strength and elastic modulus of the tar-rich coal. With equal E input, high-power microwave has a more significant effect on strength weakening, fracturing, and fragmentation of tar-rich coal. Our findings can be used for the subsequent implementation of in-situ pyrolysis and fragmentation technology of IUMM for realising the in-situ conversion, high-efficiency utilisation, and low carbon emissions of tar-rich coal.

EFFECT OF MICROWAVE RADIATION ON THE VIABILITY OF ESCHERICHIA COLI AND STAPHYLOCOCCUS AUREUS

Sterilization and decontamination of food like dairy products from bacteria that cause food poisoning is the paramount goal of food industry. Recently microwave ovens have been widely used for heating of food. This study was carried out in order to show the effect of microwave radiation on the viability of E.coli and Staphylococcus aureus in the milk. Known concentrations of E.coli and Staph,aureus in the local sheep milk were exposed to microwave radiation at 40%, 80% and 100% power levels at different time durations in seconds (0,5,30,60,120) and 0 time regarded as a control. A significant reduction in the number of colonies was detected with increasing the time of exposure for three power levels of microwave radiation compared to control. The killing effect of radiation was more associated with increasing the power level and time of exposure, in which the percentages of bacterial reduction were 12.1, 48.4 and 95.1 for E. coli at power level 40%,80% and 100% respectively while for Staph. aureus were 55.9, 92.7 and 80.7. Staph. aurues. The reduction percentages of E. coli after 120 seconds of exposure to power levels 40%,80% and 100% were 96.6, 100.0 and 98.7 respectively, while for Staph. aureus were 82.5, 99.08 and 99. It can be concluded from the results of this study that microwave radiation can be used as effective method for removing of bacteria that can cause food poisoning.

Evolution of pore-fracture structure and permeability of coal by microwave irradiation under uniaxial compression

In a natural coal reservoir environment, the coal seam is constrained by in-situ stress and gas pressure. Damage on the coal microstructure due to microwave irradiation (MI) differs significantly different from that under no-load conditions. In this study, the effect of MI on the pore-fracture structure and seepage characteristics of load-constrained coal is investigated using a custom-developed microwave fracturing experimental device, nuclear magnetic resonance test device, and permeability test device. Based on the relationship between microwave and pore-fracture structure parameters and the permeability of loaded coal, the pore-fracture structure evolution and permeability growth law of loaded coal under MI are determined. The results show that the number of micropores in coal decreases and the T2 curve of micropores is shifted to the right under the combined effect of MI and external stress load. The numbers of mesopores, macro-pores, and micro-fractures increase, and the T2 curve exhibits a broader peak span. The pore-fracture structure evolution effect of loaded coal increases with the microwave power and MI time. Under high-power MI, the pore-fracture structure evolution of the loaded coal shows a “decrease - increase – decrease” trend as the stress load increases, whereas a “decrease – increase” trend is shown under low-power MI. Under the same microwave parameters, the permeability of unloaded and loaded coal increases by a maximum of 15.7 and 364.7 times, respectively. In particular, the permeability increases by 3.1–11.4 and 17.8–49.7 times under external stress loads of 4 and 2 MPa, respectively. The combination of high MI power and short MI duration under the same microwave energy facilitates the development of the pore-fracture structure and increases the permeability of loaded coal. Microwaves have a differential thermal effect on mineral in coal, which reduce the physical properties of the coal. Pore-fracture structure and permeability are further enhanced by the stress load.

Effect of microwave radiation combined with cellulase treatment of soybean residue on the culture of Aspergillus oryzae

Soybean residue (SR) is a by-product of bean product processing with potential usefulness as a fermentation medium. However, the fermentation efficiency of SR is limited due to its low reducing sugar content. In this study, a method of microwave radiation combined with cellulase hydrolysis (MCH) was developed to increase the reducing sugar content of SR, and the effect of treated SR on fermentation by Aspergillus oryzae was evaluated. First, the process parameters, including the reaction time, pH and temperature, were optimized. Second, the effect of treated SR on fermentation by A. oryzae was evaluated, including changes in cell proliferation and protease viability. The results showed that the MCH method capitalized on the advantages of microwave radiation and cellulase and promoted the enzymatic hydrolysis of fibrous polysaccharides in the crystallization zone of SR. The reducing sugar content of SR significantly increased from 0.42 to 0.98 mg/mL after MCH treatment. In addition, treated SR effectively promoted the proliferation of A. oryzae, and the protease activity reached 111 U/mL after 3 days of fermentation. The results of this study suggested that the MCH method can effectively increase the reducing sugar content of SR to expand its use as a fermentation medium.

The Effect of Microwave Radiation on the Green Color Loss of Green Tea Powder.

Microwave radiation is one of the main heating methods for food processing, especially affecting the color quality of colorful foods. This work presents the effect of microwave radiation on the green color loss of green tea powder (GTP) by the color description (L*, a*, b*, and Ha of green tea powder, L*:whiteness/darkness, a*: redness/greenness, and b*: yellowness/blueness; Ha derived from Hunter a and b could visually describe the color space) of the Hunter color system. First, the L*, a*, and b* were determined from the GTP samples treated with various microwave powers with the change of time to investigate the kinetic of color loss. Then, the L*, a*, and b*and temperature of GTP samples with serious thickness treated with constant microwave power (700 W) for a different time were determined to study the effect of sample thickness on the color loss. Finally, the chemicals that contributed to color change in the GTP samples treated with mild, moderate, and severe radiation were analyzed. The results showed that L*, |a*| (|a*|was the absolute value of a*), b*, and Ha decreased with the power increase in microwave radiation, and their changes conformed to the first-order kinetics. The activation energies (Ea) of different thickness GTP for change of L*, a*, b*, and Ha values could be predicted with the fitting models, and Ea for 20 mm-thick GTP were approximately 1/5, 1/8, 1/8, and 1/13 of those for 4 mm-thick GTP. The color loss was mainly caused by the Mg2+ loss of chlorophylls and the formation of derivates under mild radiation, the degradation of chlorophylls and the formation of theaflavin from catechins under moderate radiation, and the degradation of chlorophylls and their derivates accompanied by Maillard reaction between reducing sugar and amino acids under severe radiation. The results indicate that sample thickness and radiation time are two key parameters to keeping the color of GTP in food processing and microwave pasteurization.

Single-cell analysis reveals microbial spore responses to microwave radiation

To determine the effects of microwave radiation at the molecular level as well as on the germination, growth and morphology of dry spores at the single-cell level. Dry Bacillus aryabhattai MCCC 1K02966 spores were microwave-treated at different powers and characterized using single-cell optical technology. As determined by laser tweezers Raman spectroscopy, the Ca[Formula: see text]-dipicolinic acid content increased and nucleic acid denaturation occurred in response to microwave treatment. Live-cell microscopy revealed that the germination and growth rates decreased as the microwave power increased. With respect to morphology, atomic force microscopy (AFM) demonstrated that spores became wrinkled and rough after microwave treatment. Furthermore, spores became smaller as the microwave power increased. Microwave treatment can damage DNA, and high-power microwaves can inhibit the germination of spores and reduce spore volumes. These results provide a new perspective on the responses of living single cells to microwave radiation and demonstrate the application of various new techniques for analyses of microorganisms at the single-cell level.