Microwave energy has potential for the efficient heating of minerals. Minerals or materials, which couple to microwave energy are called dielectrics and many valuable minerals are found to be dielectric. The mineral ilmenite is one which shows good dielectric heating characteristics. In this paper, the effect of microwave heat energy on the partial reduction of oxidized ilmenite oxidized in a conventional muffle furnace at 900°C for 3 hours is attempted. Carbon as an additive was used for reduction of ilmenite at different time intervals using microwave oven as well as microwave sintering furnace. The results indicate that at one minute, the metallic iron formed contained 0.39% and no observation in mineral phases was observed from microwave oven. At three minutes duration, a partial phase transformation of ilmenite was observed and the metallic iron contained is 1.65%. Interestingly, at six minutes duration a distinct metallic iron phase containing 32% metallic iron is seen in microwave oven. The result of preliminary investigations from microwave sintering furnace indicates that apart from metallic iron phase, the distinct Titania phase was also observed. Further studies are in progress.

Paddy drying is one of the most important and critical post-harvest processes of rice in order to prevent the growth of germs and fungi; which enhances the product storage time. In this study, drying process of Tarom Hashemi was evaluated in a continuous band microwave dryer and in a domestic microwave dryer. The obtained results indicated that the moisture ratio decreased by increasing the paddy thickness from 6 to 18 mm and the microwave power levels from 10 to 30%, whereas the seed breakage increased. The drying ratio in the domestic microwave dryer was always less than that in the continuous band microwave dryer except at the 10% input power level, whereas the seed breakage percent was always more in the domestic microwave dryer in comparison with the continuous band microwave dryer. The results indicated that the moisture diffusion coefficient was larger in drying with continuous band microwave dryer in comparison with the domestic microwave dryer at 10% microwave power levels, whereas this coefficient was less at the 50% microwave power. As a final conclusion, the use of household microwave dryer for drying the paddy is not recommended due to high percentage of seed breakage. In contrast using a continuous band microwave dryer with low input power levels (e.g., 10%) is recommended on a large scale due to the rapid moisture reduction and low seed breakage percentage.

For producing a product with better quality and nutritional characteristics, we can use a combination of hot air and microwave oven and take the advantage of both methods. In this study the effects of three drying methods (oven (40, 50 and 60 °C), microwave (90, 180 and 360 W) and the combination of microwave, oven) were investigated on fresh kiwi fruit (Hayward variety) in terms of quality properties (rehydration capacity, shrinkage and color) and nutritional properties (phenolic compounds and vitamin C). The results showed that drying of kiwi sheets using microwave, shortens drying time, although the increasing of power could adversely affects the product quality. The maximum rehydration capacity was observed in the oven method, the lowest rate of shrinkage in combined method, the lowest color changes in the microwave method, the highest phenolic compounds in combined and oven methods and highest vitamin C content in the microwave method. At the end on the basis of optimal properties, Design Expert software chose the optimum methods of kiwi drying: microwave method applying power of 90 and 360 watts, oven method applying temperature of 40 °C and combination of microwave and oven with power of 90 watts and temperature of 40 °C.

With the development of science and technology, microwave has been used in many fields such as industry, military, medicine and communication. People are living in a lapped and dynamic electromagnetic environment. Concerns about potential hazards of microwave are getting increasing attentions. The single biological effects of microwave were widely discussed which was considered harmful. Relevant safety standards had been formulated and applied. However, the real environment was more complex. Microwave was not the only factor that organisms might be affected. Other physical or chemical factors, such as ionizing radiation (IR), ultraviolet (UV), magnetic field and chemical drugs, often existed with the microwave radiation. Even the microwave itself could create combined exposure situation, because the environment consisted different frequency microwaves. Nuclear weapons and high-power radar could produce microwave and ionizing radiation. The ultraviolet ray and magnetic field generated by the instrument's operation could act on the human bodies along with the microwaves. The combination of radiofrequency therapy and chemotherapeutic agents was also commonly used in cancer therapy. Therefore, the combined biological effects of microwaves and other physical or chemical factors were very important. This review had covered the original articles in this aspect. In order to better understand the combined biological effects, the comparative studies of different frequency microwaves were also included. Differences in biological effects were found among different frequency microwaves, and the combined biological effects contained both hazards and benefits. Findings in combined biological effects were very practical for rational uses of microwave technologies.

A microwave electrothermal thruster (MET thruster) has been constructed, consisting of a microwave plasma chamber 12 cm long and 8 cm in inner diameter and a micronozzle 10 mm long with 1 mm in diameter. The microwave plasma is produced by 2.45 GHz microwave frequency at a power of 1 kW, and the feed gas is Ar at a pressure of 10^-3mTorr. Microwave energy is transmitted into the cavity and electrons sre connected to the wave's electric field. Thus, the electrons are accelerated by microwave electric fields. Microwave plasma discharge is formed based on the interaction of electrons with neutral gas particles. Then, the plasma acts as a resistive load and absorption of microwave energy, raises the temperature of the gas or plasma. Gas heating increases the gas pressure and is released through the nozzle. The plasma density and electron temperature are 2.35×〖10〗^17  m^(-3) and 1.2 eV, respectively. The thrust and specific impulse are 10 mN and 100 s

The employment of microwave energy to speed up the drying process and maintaining the quality of the dried product was recommended. Consumer demand for high-quality, healthy foods has led to continuous attempts to produce fried products with less oil content. Therefore, in this research, the effect of microwave pretreatment on the oil absorption, and quality and sensory properties of fried potato slices was investigated. First, potato slices with a thickness of 0.5 cm were prepared. To apply microwave treatment, the samples were placed inside the microwave device for 0, 1, 2 and 3 min. The treated slices were fried by a fryer at a temperature of 160°C. Finally, the samples were examined for frying time, moisture content, oil absorption, hardness, color parameters, color change index, surface changes, and sensory properties. The texture hardness of fried potato slices was measured using a texture analyser. The puncture speed of the probe into the sample was considered to be 1 mm/s. The use of microwave pretreatment and exposure to microwaves decreased the frying time of potato slices. The lowest moisture percentage and oil absorption was related to the slices treated by microwave for 3 min, which had a significant difference with the control sample (p<0.05). The oil absorption of potato slices treated by microwave for 0, 1, 2, and 3 min and fried at 160°C was 19.34, 18.35, 13.95, and 10.00%, respectively. The texture hardness of fried potato slices increased with increasing microwave treatment time. The hardness of potato slices treated by microwave for 0, 1, 2, and 3 min and fried at 160°C was 0.60, 0.61, 0.70 and 0.75 N, respectively. After 3 min of microwave treatment, the lightness and yellowness indexes increased significantly from 79.42 to 83.08, and 23.10 to 31.03, respectively, and the redness (greenness) index also decreased significantly from -3.56 to -6.72 (p<0.05). Applying microwave pretreatment decreased the lightness index and increased the redness index of fried potato slices. The use of microwave pretreatment reduced the size of fried potato slices, and the highest value of size change was related to the sample treated by microwave for 3 min. In terms of appearance, odor, texture and taste acceptance scores, as well as overall acceptance, fried potato slices pretreated with microwave for 2 min had the highest score. Treating potato slices with the microwaves shortened frying time, reduced oil absorption, improved appearance color and increased sensory acceptability of product; therefore, it is recommended to treat potato with the microwave before frying.

In this study, green pepper was dried by a laboratory scale microwave-convective dryer. The effects of microwave power on drying rate, effective moisture diffusivity, and energy consumption of green pepper were studied at four different microwave powers of 180, 360, 540, and 720W. The drying data were fitted to the four thin-layer drying models. The moisture reduction of the green pepper samples, from 2.894 to 0.1 kg water kg-1 dry matter, lasted 120 and 495 seconds at microwave power of 720 and 180W, respectively.The drying model assessment revealed that the Midilli model exhibited the best performance in fitting the experimental data, providing the highest R2 (0.927), and the lowest RMSE (0.2065) and
2 (0.0555). With increase in microwave (drying) power from 180 to 720W, moisture diffusivity increased from 6.249×10-9 to 3.445×10-8 m2 s-1. Results also indicated that drying rate increased by increasing the microwave power and decreased continuously with passing of drying time and decreasing moisture content. The least specific energy consumption (7.2 MJ kg-1 water) was at microwave power of 360 W and the highest (9.26 MJ kg-1 water) was at 540W.

Quality changes of red pitaya (Hylocereus undatus) slices dried in hot air, microwave-hot air and microwave-vacuum dryers were investigated. The quality parameters were colour, water activity, shrinkage, rehydration ratio, ascorbic acid content and visual market quality. Microwave-vacuum produced pitaya with the best quality compared to hot air and microwave-hot air. Pitaya dried in microwave vacuum had the highest rehydration ratio while the other methods presented similar rehydration ratios. Ascorbic acid in dried pitaya was also better retained when drying by microwave-vacuum. Apart from that, the drying time of pitaya dried in microwave-vacuum could be reduced by 83% compared to hot air.

In this research, the effect of microwave pre-treatment on qualitative characteristics and sensory properties of air-dried potato sticks was investigated. Different powers (180-900W) and times (1-5 minutes) of microwave were used before air-drying of samples. The moisture content, rehydration, shrinkage, browning, colour indices and sensory properties (taste, colour, shape, strength, and total acceptance) of potato samples were evaluated after the drying process and the response surface method (RSM) was used to determine the optimal conditions for the microwave pre-treatment. Used for the highest levels of physicochemical and sensory properties. The results showed that, with increasing the power and time of the microwave oven resulted in an increase in the moisture content, shrinkage, rehydration and total colour change of the samples. Sensory evaluation results showed that in the microwave pre-treatment, only the scores of the taste and colour of potato samples were influenced by the microwave power and time. According to the results of optimization by the surface response method, the power of 180 Watts and the time of 3.5 minutes for the microwave pre-treatment were introduced as optimum conditions.

A novel approach for bio-lubricant production from rapeseed oil-based biodiesel using ultrasound irradiation: Multi-objective optimization Moringa oil is used as a useful oil in the food, medicinal, cosmetic and health industries. Also past research has shown that microwaves can increase the extraction efficiency of oil by disintegrating the cellular structure of oil seed. Therefore, in this research, for increasing oil extraction efficiency, microwave pretreatment was used before oil extraction from Moringa seeds by spiral press. In this study, the optimization of oil mechanical extraction from Moringa seeds was done using the Response Surface Methodology. In this study, extraction experiments were done with microwave pretreatment at different level of times (2, 3 and 4 min) and powers (200, 400 and 600 W). The results showed that the extraction efficiency increases and then decreases by increasing microwave time and microwave power. The optimum extraction efficiency was 56.55% during the microwave action time of 3.02 min and the microwave power intensity of 380.92 W. Due to the high values of correlation coefficients (R2 = 0.97) the predicted model for oil extraction efficiency can be evaluated properly.