Microwave Oven Research Articles

Microwave-synthesized V2O5 nanoparticles for ammonia sensing at room temperature

We introduce a process for synthesizing V2O5 nano particles directly from vanadium powder using a microwave oven in just 5 min. These nanoparticles are oval-shaped with an average diameter of 9 nm. These V2O5 nanoparticles are capable of detecting 1 ppm NH3 at room temperature with the response of 1.16 and the response/recovery times of 15 s and 326 s, respectively. Notably, the NH3 sensing characteristics of these V2O5 nanoparticles are almost unaffected by the humidity in the air and remain unchanged after at least 60 days of measurement. Therefore, V2O5 nanoparticles synthesized using microwave techniques are a material with great potential for application as low-energy NH3 sensors.

Development of a CaCO3 Precipitation Method Using a Peptide and Microwaves Generated by a Magnetron

Microwave applications, such as microwave ovens and mobile phones, are ubiquitous and indispensable in modern society. As the utilization of microwave technology is becoming more widespread, the effects of microwaves on living organisms and physiological processes have received increased attention. This study aimed to investigate the effects of microwaves on calcium carbonate biomineralization as a model biochemical process. A magnetron oscillator was used to generate 2450 MHz microwaves because magnetrons are relatively inexpensive and widespread. We conducted transmission electron microscopy (TEM), atomic force microscopy (AFM), TEM-electron energy-loss spectroscopy (EELS), dynamic light scattering (DLS), and high-performance liquid chromatography (HPLC) measurements to analyze the calcium carbonate precipitates. Our findings showed the formation of string-like precipitates of calcium carbonate upon microwave irradiation from one direction, similar to those obtained using a semiconductor oscillator, as reported previously. This implied that the distribution of the frequency had little effect on the morphology. Furthermore, spherical precipitates were obtained upon microwave irradiation from two directions, indicating that the morphology could be controlled by varying the direction of microwave irradiation. Magnetrons are versatile and also used in large-scale production; thus, this method has potential in medical and industrial applications.

Determination of Electrolytes and Trace Elements in Biological Samples from Patients with Altered Semen Parameters: a Correlational Analysis.

The effects of important nutrients such as calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), selenium (Se), and zinc (Zn) have been investigated in relation to male fertility due to their roles in proper spermatogenesis, sperm maturation, motility, and optimal sperm function. An imbalance between these elements has been associated with several pathologic conditions and male reproductive issues. The purpose of this study was to determine the essential trace and electrolytes elements, such as Ca, Cu, Fe, Mg, Se, and Zn, in human biological samples (blood, serum, and semen) from patients with male infertility. This study used correlational analysis to determine the potential associations between these elements and male fertility. Imbalances in these elements have been linked to various pathological conditions and male reproductive issues. One hundred eighty referent male adults and two hundred twenty-nine patients diagnosed with subtypes of infertility were included in the study, divided into two age groups. Acid digestion was controlled using a microwave oven, and the essential trace elements and electrolytes in the oxidized biological samples were determined using atomic absorption spectrometry. Certified reference materials of blood and serum were used to validate the accuracy of the methodology. The results showed that the concentrations of Ca, Cu, Fe, Mg, Se, and Zn in the blood, serum, and seminal plasma of male adults in all age groups were higher than those in patients with different infertility phenotypes. Essential element deficiency in all biological fluid samples may significantly negatively affect human reproductive health and lead to male infertility. Through a multidimensional approach, our study sought to unravel the intricate biochemical signatures associated with OAT, providing insights that may shape the landscape of diagnostic and therapeutic strategies for male reproductive health.

Drying Kinetics of Grated Ginger (Zingiber officinale) In a Microwave Oven with Control of Power

The drying of ginger in Mexico is not commercially done, which causes a large amount of product that is not consumed in the form of fresh vegetable, to be wasted. To obtain a more sustainable and profitable presentation of the product, it was proposed to analyze the drying kinetics and the time consumed to perform this operation, having as quality parameters the organoleptic properties, namely, color, taste and smell. The kinetics of the drying of grated ginger (Zingiber officinale) was analyzed. A microwave oven with power values of 15 and 20 W/ g of product, was used. This energy was lower than that required by other drying methods, the periods of time used were 35 min for 20 W/g and 45 min for 15 W/g. The numerical model that best represents the kinetics was the exponential one. The color variations at the end of the process were greater for the power of 15 W/g, which turned into a product of acceptable appearance, the taste was slightly more acidic, but the smell lasted very little.

Metal Ion Microwave-Assisted Depolymerization of Poly(Ethylene Terephthalate): A Zinc Salts-Based Deep Eutectic Solvent as Case Study

In this study, a new and very quick method to depolymerize PET plastics is reported. The depolymerization experiments were conducted using a type-IV deep eutectic solvent containing ZnCl2 and urea, and a microwave oven as reactor. Different combinations of power and reaction times were employed while keeping the total energy constant. Successful conversions were obtained carrying out the process at 180 W for 2 min and 360 W for 1 min, whereas at higher powers and shorter times, an inclusion likely occurs of some solvent into the structure of the recovered PET flakes, as suggested by the porosity of the flakes, imaged by SEM microscopy. The flakes increase their crystalline character during the treatment, as indicated by the appearance of narrow diffraction peaks in the XRD patterns, at variance with the broad signals observed in the case of the pristine amorphous polymer. The NMR analysis of the supernatant liquid above the partially solubilized PET shows the presence of terephthalic acid peaks. The infrared spectra of the solid powder achieved upon the acidic treatment of the extract reveal the presence of C=O stretching peaks and the absence of typical CH2 wagging absorptions that satisfactorily comply with the presence of terephthalic acid.

Effect of Microwave Irradiation on Mechanical Properties and Microstructures of Minerals

Microwave-assisted rock breaking is a new and promising technology for the tunneling and drilling industry. Minerals in rocks have an important influence on the effect of microwave-assisted rock breaking. In this paper, common minerals in rocks such as potash feldspar (hereafter referred to as K-feldspar), calcite and pyroxene were selected as samples, and a lot of microwave irradiation tests were carried out by using a hamilab-v1500 microwave oven. The mass, strength and microstructure of the rock samples were tested before and after microwave irradiation. The change law of the mineral mass, strength and microstructure with regard to temperature was analyzed, and the influence mechanism was discussed. The results show that the strength of K-feldspar increases from 20 °C to 400 °C but decreases significantly when it is higher than 400 °C; the strength of pyroxene increases from 20 °C to 600 °C but decreases when it is higher than 600 °C; the strength of calcite decreases with the increase in temperature. As for the weakening pattern, pyroxene shows drawstring, step and flow with the increase in temperature, but K-feldspar and calcite show that failure occurs along the cleavage plane of the crystal structure. The higher the temperature of microwave irradiation, the finer the pattern at the fractured zone is, and the more fragmented it becomes; the loss of mineral mass increases with the increase in the temperature of microwave irradiation.

Isomerization of maltose to maltulose under microwave heating using uncalcined scallop shell powder

Uncalcined scallop shell powder, consisting mainly of calcium carbonate, and an aqueous maltose solution were placed in a pressure-resistant vessel and heated in a domestic microwave oven to isomerize maltose to maltulose. When a maltose solution (50 mL) was heated at a power of 700 W, a high maltulose yield of approximately 30 % was achieved in as short a time as 105 s. As the reaction progressed, the shell powder dissolved and neutralized acidic by-products to suppress the decrease in pH, keeping the pH above 7, where the isomerization by Lobry de Bruyn-Alberda van Ekenstein transformation proceeded. The average selectivity for isomerization of maltose to maltulose under various reaction conditions was 0.822. This would be because the shell powder kept the pH of the reaction solution in the range of 7–9 and suppressed the progression of side reactions. The coloration of the reaction solution increased rapidly when the yield of maltulose approached its maximum value. This indicated that if the reaction were to be stopped when the yield of maltulose was close to its maximum value, a high yield of maltulose solution with low coloration could be obtained.

Tissue Processing using Microwave Oven: A Boon for Histology Slide Preparation

Background: Tissue processing is an important step in histology laboratories. Routine tissue processing is time-consuming. Due to the same time factor, microwave tissue processing is now increasingly being used in many histology and pathology laboratories. Objective: To compare the time taken to process the tissues using the routine conventional and microwave methods. Methods: The study was conducted in the Histology laboratory. 100 slides (50 conventional method + 50 microwave method) were processed using both methods, sectioned, stained, and analyzed by an independent observer who was unaware of the processing method. Results: The study showed a significant decrease in processing time by the microwave method (p-value < .0001). Conclusion: The present study concluded that the time taken for dehydrating, clearing, and embedding the tissues in paraffin wax was found to be considerably lower than that taken for the conventional method of tissue processing. Chloroform was used here as a clearing agent, and it had desirable effects. KEYWORDS: Microwave tissue processing, Conventional tissue processing.

Production of Glass Foam in a Microwave Oven Using Agro-Industrial Waste as Raw Material

Climate change is characterized by shifts in temperature and climate patterns. Constructing new high-rise environments using materials that incorporate agro-industrial waste can help mitigate this impact without compromising technological properties. This study produced vitreous foams intended to replace natural aggregates in lightweight concrete partially. These foams were sintered in a microwave oven at temperatures of 750 °C, 800 °C, and 850 °C, utilizing glass powder and sugarcane bagasse ash as raw materials. The homogenization and preparation of these materials were conducted through a mechanical pelletization process, employing a constant rotation engine at approximately 40 rpm. The efficacy of microwave sintering was assessed by comparing the outcomes with those from sintering in a conventional electric muffle furnace under identical conditions. The results indicated that the microwave-sintered vitreous foams exhibited the following values for apparent density (≤0.30 g/cm3), porosity (86% to 94%), and compressive strength (0.48 MPa to 0.58 MPa), which align with the global standards for commercial vitreous foams. The microwave sintering route proved to be economically feasible by reducing sintering time and, consequently, energy costs, without sacrificing technological properties. The materials produced in this study offer a promising solution to minimize the environmental impact associated with constructing new buildings, particularly tall structures. Additionally, they support the circular economy by converting waste into valuable by-products.

Two-phase numerical simulation of thermal and solutal transport exploration of a non-Newtonian nanomaterial flow past a stretching surface with chemical reaction

Abstract Non-uniform heat sources and sinks are used to control the temperature of the reaction and ensure that it proceeds at the desired rate. It is worldwide in nature and may be found in all engineering applications such as nuclear reactors, electronic devices, chemical reactors, etc. In food processing, heat is used to cook such as microwave ovens, pasteurize infrared heaters, and sterilize food products. Non-uniform heat sources are mainly used in biomedical applications, such as hyperthermia cancer treatment, to target and kill cancer cells. Because of its ubiquitous nature, the idea is taken as our subject of study. Heat and species transfer analysis of a non-Newtonian fluid flow model under magnetic effects past an extensible moving sheet is modelled and examined. Homogeneous chemical reaction inside the fluid medium is also investigated. This natural phenomenon is framed as a set of Prandtl boundary layer equations under the assumed convective surface boundary constraint. Self-similarity transformation is employed to convert framed boundary layer equations to ordinary differential equations. The resultant system is solved using the efficient finite difference utilized Keller box method with the help of MATLAB programming. The influence of various fluid-affecting parameters on fluid momentum, energy, species diffusion and wall drag, heat, and mass transfer coefficients is studied. Accelerating the Weissenberg number decelerates the fluid velocity. The temperature of the fluid rises due to variations in the non-uniform heat source and sink parameters. Ohmic dissipation affects the temperature profile significantly. Species diffusion reduces when thermophoresis parameter and non-uniform heat source and sink parameters vary. The Eckert number enhances the heat and diffusion transfer rate. Increasing the chemical reaction parameter decreases the shear wall stress and energy transmission rate while improving the diffusion rate. The wall drag coefficient and Sherwood number decrease as the thermophoretic parameter increases whereas the Nusselt number increases. We hope that this work will act as a reference for future scholars who will have to deal with urgent problems related to industrial and technical enclosures.

A review of 2.45 GHz microstrip patch antennas for wireless applications

Recently, microstrip patch antennas have become popular. Due to their ubiquity, these antennas have more uses every day. In this research paper, a 2.45 GHz microstrip patch antenna has been reviewed and analyzed. Different substrate materials have been used to make these antennas, and their thickness is different. Various antennas are designed based on the application, such as rectangular, square, triangle, ring, donut, and dipole. Other types of software were used to design the antenna, including CST, HFSS, MATLAB, ADS, and FEKO. Microstrip patch antenna design is a relatively new field of study for wireless applications. Several devices are linked to send or receive radio waves using a single antenna. Antennas designed for 2.45 GHz are used in various wireless communication systems, including television broadcasts, microwave ovens, mobile phones, wireless local area network (WLAN), Bluetooth, global positioning system (GPS), and two-way radios. This article looks at the geometric structures of antennas, including their many parameters and materials and the many different shapes they can take. In addition, the substrate materials, the loss tangent, the thickness, the return loss, the bandwidth, the voltage standing wave ratio (VSWR), the gain, and the directivity of previous articles will also be discussed.

Peptidomic profile and α-glucosidase inhibitory activity of cooked and gastrointestinal digested legumes

Legumes are a good source of bioactive compounds, including peptides with antidiabetic potential. The α-glucosidase inhibitory activity of simulated gastrointestinal digested (GID) soybean, chickpea, green pea, and navy bean was determined after using three different household cooking methods (conventional, pressure, and microwave cooking). Samples were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC), and the fractions responsible for the α-glucosidase inhibitory activity were isolated. Lastly, peptides were identified by mass spectrometry in tandem (MS/MS) and in silico analyses were done to hypothesise potentially bioactive sequences. The results indicated that all legume extracts exert α-glucosidase inhibitory activity after thermal treatment and GID. Peptide profiles obtained by RP-HPLC showed the highest generation of peptides after the intestinal digestion phase, with small changes between thermal treatments. Best α-glucosidase inhibitory activity was observed in fraction 2 of all gastrointestinal digested samples, with values between 40 % and 62 % inhibition. In soybean, green pea, and navy bean, conventional-cooked samples showed the highest activity, while the pressure-cooked treatment resulted in significantly higher activity in chickpea samples. Finally, 48 peptides were identified by MS/MS and 13 were found as potentially bioactive using in silico tools, expanding previous knowledge on antidiabetic peptides derived from legumes.

Evaluation of contamination of chemical elements in fish samples using human health risk assessment indices

This work reports carcinogenic and non-carcinogenic indices in inorganic assessing contamination in fish samples. In this context, fifty-one sardine samples were commercially acquired in seventeen neighborhoods and were toxicologically evaluated. These samples were washed, frozen, freeze-dried, and digested in a microwave oven. Six chemical elements were quantified using inductively coupled plasma optical emission spectrometry. The average levels on a wet basis expressed as μg g−1, ranged from 0.34 to 2.03 for total arsenic, 0.12 to 4.42 for copper, 0.04 to 0.26 for chromium, 4.61 to 99.39 for iron, 3.73 to 34.99 for zinc, and 0.01 to 4.07 for manganese. The estimated weekly intake, target hazard quotient, maximum safe consumption quantity, and carcinogenic risk indices were applied to the data found, denoting that arsenic levels can cause carcinogenic and non-carcinogenic adverse effects on the health of residents. However, these risks are minimized because the evaluation indices were calculated by total arsenic concentrations. In fish matrices, the arsenic is predominantly arsenobetaine, which has low toxicity. Samples from ten neighborhoods also showed copper concentrations that indicate the likelihood of carcinogenic risks. The chromium, iron, zinc, and manganese levels do not pose any health risks to consumers.

Study on Multiple Effects of Self-Healing Properties and Thermal Characteristics of Asphalt Pavement

Asphalt pavements are prone to cracking in low-temperature environments, and microwave heating (MH) can heal the cracks effectively. This research mainly investigates the different MH effects on the self-healing properties of asphalt mixtures. With this objective, the three-point splitting test is conducted to generate the cracks. A microwave oven is employed to heat the samples, and a thermal camera measures the surface temperature. Results indicate that heating power and time show a positive linear correlation with healing efficiency, and the HI of the samples can reach over 80%. The HI of the samples decreases with the heating cycle, but the sample with reasonable power and time still has a HI higher than 70% after 5 cycles. The temperature peaks on thermal images indicate that uneven heating exists during heating, but the heating uniformity is within an acceptable range. The healing efficiency level (HEL) suggests that asphalt mixtures have very low inefficient healing behavior if the heating time is below 45 s, but HEL can reach 86.14% at 700 W after 60 s. Furthermore, although the HI of strength shows ideal results, the recovery of other crack parameters, including stiffness, fracture energy, flexible index, and crack resistance index, are not satisfactory.

Development of Fly Ash and Light Weight Mineral Granules Based Thermal Insulated Ceramic Container Bases for Keeping Hot Pot & Hot Bowl

Thermal insulation based product development is the most important concern in the present age because we are using so many types of heating and cooking and baking devices and electronic equipment like microwave ovens, induction cook tops, Oven toaster Grillers, Electric tandoor, Roti makers, domestic furnace and electronic coffee & tea makers. When we take out our bowls and pots from the microwave ovens and such type of other kitchen devices then heat present in the walls of the containers like utensil, bowl & pot and heat present in the cooked food damages the top of the table and table covers. In order to prevent such things there is a burning need of development of thermal insulation bases and mats.

Advanced Integration of Microwave Kiln Technology in Enhancing the Lost-Wax Glass Casting Process: A Study on Methodological Innovations and Practical Implications

Lost-wax glass casting, an esteemed yet technically demanding art form, traditionally relies on specialized, costly kiln equipment, presenting significant barriers to artists regarding equipment affordability, energy efficiency, and the technical mastery required for temperature control. Therefore, this study introduces an innovative approach by integrating a microwave kiln with standard household microwave ovens, thus facilitating the lost-wax glass casting process. This methodological adaptation allows artists to employ readily available home appliances for glass creation, significantly reducing the process’s cost and complexity. Our experimental investigations reveal that, by using a 500W household microwave oven for heating, the silicon carbide (SiC) in microwave kilns can efficiently absorb microwave energy, allowing the kilns to reach temperatures exceeding 700 °C, a critical threshold for casting glass softening. We further demonstrate that by adjusting the number of heating cycles, producing high-quality, three-dimensional(3D) glass artworks is feasible, even for large-scale projects. In addition, the microwave kiln can be used as an effective cooling tool to uniformly cool the formed casting glass. This study presents a possible alternative to conventional kiln technology and marks a paradigm shift in glassmaking, offering a more accessible and sustainable avenue for artists and practitioners.

Identification of turntable function in a solid-state microwave heating process with diverse frequency-shifting strategies applied

The turntable has been used in conventional magnetron-based microwave ovens to improve the heating uniformity. Meanwhile, with the emerging solid-state technique, well-designed frequency-shifting strategies also show promise in achieving improved microwave outcomes without a rotating turntable. This study used modeling tools to comprehensively assess the turntable function under various conditions, where the affecting factors included vertical and horizontal positions of food, rotation status of the turntable, frequency-shifting strategy, and food configurations. Results illustrated that the elevation of food by the turntable is more critical to power efficiency and heating uniformity, while rotation mainly works to narrow the temperature difference between hot and cold spots. Moreover, the complementary-shifting strategy lessened the rotation function of the turntable. Hence, in a solid-state microwave system embedded with a proper frequency-shifting strategy, a simpler supporting component shall replace the current rotating turntable, streamlining the oven design without compromising the microwave performance. Industrial relevanceThis study comprehensively evaluated functions of the turntable, a conventional component, inside a novel microwave system design utilizing solid-state instead of the magnetron as its power source. Based on the evaluation, the well-implemented frequency strategies hold promise to achieve improved microwave performance with a simpler supporting component to elevate the food, rather than relying on a rotating turntable. These findings provide novel insights for designing the next-generation microwave ovens.

Development of a novel flattened magnetron for household microwave oven

This paper presents a design scheme of a Novel Flattened Magnetron for Household Microwave Oven, which makes a breakthrough in the magnetic circuit of the existing magnetron and adopts the symmetrical enhanced magnetic circuit design scheme. Magnetron width has been successfully reduced from 80 mm to 50 mm. The reduction is up to 37.5%. Based on the size of the flattened magnetic circuit system, the theory of magnetron noise, and the knowledge of LC low-pass filters, a filtering structure for the flattened magnetron is proposed. Electromagnetic simulation shows that the magnetron with the new magnetic circuit structure can still meet the design specifications of the magnetron used in the existing microwave oven. An experiment was conducted to verify the proposed design's performance, and it was found to be similar to the existing conventional magnetron.

Impact of rice variety, cooking equipment and pretreatment method on the quality of lightly milled rice

Lightly milled rice is a healthier choice compared to refined white rice. In this study, the effects of variety, cooking equipment and pretreatment method on the quality of six varieties of lightly milled rice from China after cooking was investigated through physics, chemistry and instrumental analysis method. Nanjing-No.5055 has the best eating quality, Xiadao-No.1 has higher appearance score, and Fengliangyouxiang-No.1 has the lowest glycemic index. Compared with microwave oven and electric cooker, steamer has a more significant positive impact on component retention, eating quality and sensory quality, but the former has lower cooking time and higher glycemic index. Soaking can effectively improve the water absorption rate, thus reducing hardness. Cleaning affects component retention but is beneficial for sensory quality. The most obvious variation in organizational structure can be observed in the steamer and soaking processes. These findings could serve as a valuable reference for the processing of lightly milled rice.

Safety assessment of the process Martogg Group, based on the EREMA Advanced technology, used to recycle post-consumer PET into food contact materials.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids assessed the safety of the recycling process Martogg Group (EU register number RECYC321), which uses the EREMA Advanced technology. The input material is ■■■■■ washed and dried poly(ethylene terephthalate) (PET) flakes originating from collected post-consumer PET containers, including no more than 5% PET from non-food consumer applications. The flakes are heated in continuous reactors ■■■■■ before being extruded. Having examined the challenge test provided, the Panel concluded that the continuous decontamination steps (Steps 2 and 3), for which a challenge test was provided, are critical in determining the decontamination efficiency of the process. The operating parameters to control the performance of this step are temperature, pressure and residence time. It was demonstrated that this recycling process is able to ensure a level of migration of potential unknown contaminants into food below the conservatively modelled migration of 0.1 μg/kg food derived from the exposure scenario for infants when such recycled PET is used at up to 100%. Therefore, the Panel concluded that the recycled PET obtained from this process is not of safety concern when used at up to 100% for the manufacture of materials and articles for contact with all types of foodstuffs, including drinking water, for long-term storage at room temperature or below, with or without hotfill. Articles made of this recycled PET are not intended to be used in microwave or conventional ovens and such uses are not covered by this evaluation.