Laboratory Microwave Research Articles

Preparation of uranium-plutonium oxide solid solution powder from ammonium uranyl-plutonyl carbonate in a laboratory microwave unit

The method of obtaining a solid solution powder of uranium-plutonium oxides (with 38% plutonium content) from the AUPuC pulp of the process (ammonium uranyl-plutonyl carbonate) using microwave radiation in reducing and atmospheric environments was proposed and tested at the laboratory level. For research purposes, the pulp obtained by coprecipitation of uranium and plutonium from nitrate solution (stripping product simulator) was prepared in advance. The process consists of three main stages: oxidation of Pu(IV) to Pu(VI), precipitation, and conversion in a laboratory microwave unit. According to the X-ray phase analysis, the powder obtained in a reducing atmosphere is a solid cubic solution (UxPu1–x)O2. The powder obtained in an atmospheric environment is a mixture of two oxides, PuO2 and U3O8. Scanning electron microscopy and electron probe microanalysis of the powder obtained in an atmospheric environment showed a fairly uniform distribution of U, Pu, and O in the solid phase.

Offset-fed Slotted Antenna Practically Loaded with Split Ring as Water Quality Sensor for X-Band Industrial Applications

This article communicates an offset-fed split ring loaded slotted-antenna design, testing, and analysis for different water quality sensor. The antenna was designed to resonate at 10GHz on a low-cost FR-4 substrate of dimensions 0.621λo×0.467λo×.053λo, where λo is the free space wavelength. The measured antenna parameters are found in excellent agreements. The antenna achieves a gain of 7.61dBi with nearly unidirectional radiation pattern and a radiation efficiency of 76% at 10GHz. Further, the research is explored to use the antenna as a water sample sensor. Different water samples are tested with the antenna by dipping the antenna into the water samples and in the second case contactless measurements at 10mm apart from the upper water level in the container. The quality of water is examined by observing the shift in the resonant frequency (fr), antenna quality factor with different total dissolved solvents (TDS) water samples, and changes in the reflection coefficient (S11) values in the water samples. It is observed that the antenna shows less than 1.5% numerical sensitivity (NS) with fr and high NS with the S11. The S11 and bandwidth of the antenna vary with different water samples. This antenna is suitable for X-band industrial and microwave laboratory applications.

Jahn-Teller induced microwave spectra of the C70 + fullerene cation.

The C70 molecule is apolar. Upon ionization Jahn-Teller effects occur that distort the D5h neutral symmetry to Cs. This point group is polar thus ionization induces a permanent electric dipole moment in C70. The goal of the present calculations is to compute the equilibrium geometry and dipole moment of the C70 + cation by various DFT methods and to simulate microwave spectra. Using the Gaussian16 quantum chemistry program rotational constants, Cartesian dipole moment components, and the resultant dipole, as well as the Jahn-Teller stabilization energy and the HOMO-LUMO gaps were obtained. The microwave rotational spectra at gas phase temperatures 2.73 K and 10K were simulated using the Pgopher software. These spectra may serve as starting point for laboratory microwave measurements and as screening guide in radio astronomical searches. The static Jahn-Teller effect in C70 + is the consequence of the mixing of the two highest ground state occupied orbitals, thus it is a pseudo Jahn-Teller effect.

Preparation of Uranium/Plutonium Oxide Solid Solution Powder from Ammonium Uranyl–Plutonyl Carbonate in a Laboratory Microwave Unit

Preparation of Uranium/Plutonium Oxide Solid Solution Powder from Ammonium Uranyl–Plutonyl Carbonate in a Laboratory Microwave Unit

Biogenic Synthesis and Characterization of Gold Nanoparticles from Morus alba L. Leaves by Microwave Extraction Method

The aim of this study was to investigate the rapid, simple, and inexpensive biosynthesis and characterization of gold nanoparticles (AuNPs) an extract from leaves of Morus alba L. The generated gold nanoparticles were characterized by UV-Vis spectroscopy, TEM, FT-IR and zeta-sizer. For the biogenesis of gold nanoparticles, Morus alba L. (Mulberry) leaves and HAuCl4.3H2O solution were utilized as the starting ingredients. Fresh leaves of Morus alba L. were collected from Turkey (Trabzon). 100 mL of distilled water was mixed with 10 g of dried material for 120 minutes. The mixture was then extracted using a laboratory microwave for 4 minutes at 600 W. For the biosynthesis of AuNPs, different amounts 100 ml of (0.5 mM, 1 mM) aqueous HAuCl4.3H2O solution of leaf extract (0.5 and 1 mL) were mixed with HAuCl4. 3H2O solution, and then the mixture was placed in a household microwave at 90 W for 1 to 30 minutes. UV-vis spectroscopy, TEM, FT-IR and zeta-sizer were performed to characterize the produced gold nanoparticles. UV-Vis absorption spectra was measured using a Shimadzu UV-1240 UV-Vis spectrophotometer with a wave length range of 300 to 800 nm. The development of AuNPs was indicated by the mixture's purple-red colour. From the results of zetasizer study, the average particle size of the AuNPs was 78.95±0.57 nm, the zeta potential was 12.9±0.808 mV, and the polydispersity index was 0.321±0.004. When the AuNP solutions were kept in the refrigerator, their UV-Vis absorption spectra rarely changed and remained stable for around 2 to 2.5 months.

The microwave bacteriome: biodiversity of domestic and laboratory microwave ovens.

Microwaves have become an essential part of the modern kitchen, but their potential as a reservoir for bacterial colonization and the microbial composition within them remain largely unexplored. In this study, we investigated the bacterial communities in microwave ovens and compared the microbial composition of domestic microwaves, microwaves used in shared large spaces, and laboratory microwaves, using next-generation sequencing and culturing techniques. The microwave oven bacterial population was dominated by Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes, similar to the bacterial composition of human skin. Comparison with other environments revealed that the bacterial composition of domestic microwaves was similar to that of kitchen surfaces, whereas laboratory microwaves had a higher abundance of taxa known for their ability to withstand microwave radiation, high temperatures and desiccation. These results suggest that different selective pressures, such as human contact, nutrient availability and radiation levels, may explain the differences observed between domestic and laboratory microwaves. Overall, this study provides valuable insights into microwave ovens bacterial communities and their potential biotechnological applications.

Optimization of crack healing in steel bridge deck asphalt pavement based on the microwave heating technology

Microwave technology can heal cracks in asphalt pavements by heating the pavement. When it is used to repair cracks in steel deck asphalt pavement (SBDAP), the temperature of the SBDAP is greatly increased because the steel deck reflects the microwaves, allowing the microwaves to reheat the SBDAP. This study established a numerical model for microwave-heated SBDAP, and analyzed the effects of the waveguide height above the pavement surface, the thickness of the SBDAP, microwave power and heating time on the average of the temperature gradient (Tavg) and the standard deviation of the temperature gradient (Tstd) of the SBDAP. The feasibility of the numerical model was validated through the laboratory microwave heating tests. The prediction models of Tstd and Tavg under the effect of four influencing factors were developed by response surface methodology, and the validity of the prediction models was verified based on the analysis of R2 values and analysis of variance. With the prediction models of Tavg and Tstd as optimization functions, the optimal combination of the aforementioned influencing factors was determined using the genetic algorithm. In summary, the results of this study can effectively guide the field construction of microwave heating technology to repair SBDAP cracks.

3D indoor Propagation Simulator using Ray Tracing for 10-20 GHz frequency Band on GPU with NVIDIA-Optix under Unity graphic Engine

In this paper a novel Ray Tracing 3D indoor propagation simulator at frequencies of 10-20 GHz using GPU is presented. To carry out the simulation, software tools as Nvidia CUDA 10.0, CMake 3.19.4, Nvidia OPTIX 6.5, Microsoft Visual Studio Community 2017 and Unity 2018.4.21f1 was used. Two indoor with line-of-sight (LOS) scenarios were defined within the Faculty of Informatics and Electronics al the Escuela Superior Politécnica de Chimborazo (ESPOCH), one in the Microwave Laboratory, with minimum and maximum distances between Transmitter and Receiver of 0.34m (far field) and 7m, respectively; and the second stage is located in the hall on the ground floor of the FIE building with minimum and maximum distances of 6 and 12m, respectively. In those scenarios, both, real and simulated measurements were made with frequency hops of 1GHz. For the simulation, a ray tracing propagation technique under GPU using NVIDEA-Optix was used. By comparing simulated and measurement power, it was observed a difference of 10 dB approximately.

Detailed investigation on new chemical-free methods for silk sericin extraction

The degumming of silk and the recovery of sericin from wastewater can be performed in different ways. In this study, the quantity and quality of silk sericin from mulberry silkworms are evaluated through four degumming methods: the alkaline, the hot water, the high temperature and high pressure (HTHP) and the microwave methods. The sericin powders obtained were rigorously characterized through the elementary composition, Scanning Electron Microscopy (SEM), spectroscopy (UV, IR and fluorescence), secondary structure, thermal stability, molecular weight analysis, and compared to a commercial sericin. The results demonstrate that microwave is the most effective degumming method because all of the sericin contained in the cocoons is recovered. It was shown that sericin samples obtained by different extraction methods have similar composition. However, differences were observed in the chain length of sericin samples. The molecular weights of sericin are high for alkaline and microwave degumming and lower molecular weights are observed for sericin from hot water and HTHP degumming. The analysis of the secondary structure confirms that sericin is highly structured in aggregated or in β sheet conformation. The morphology and the structural organization of the sericin can be altered from one extraction to another, modifying sericin properties. • Four degumming methods of silk sericin from Bombyx Mori have been compared • Development of a new process for the sericin recovery with a laboratory microwave • Microwaves degumming is the most efficient extraction with 99.8% yield of sericin • Sericin extracts have the same composition and are similar to a commercial sericin • Extraction methods influence the molecular weight and solubility of sericin in water

Monitoring of the content of heavy metals in sunflower seeds and its processing products in Ukraine for 2018–2021

The article presents the results of research conducted at the State Research Institute of Laboratory Diagnostics and Veterinary-Sanitary Examination from 2018 to 2021 regarding the content of trace elements and toxic elements in sunflower seeds and their products of domestic production. During the studied period, 62 samples of sunflower seeds, 345 samples of sunflower meal, 289 samples of sunflower cake, and 68 samples of halva were analyzed. The preparation of samples was carried out by acid decomposition in nitric acid using a laboratory microwave system with closed-type autoclaves. The content of Lead, Cadmium, and Arsenic was determined by the method of atomic absorption spectrometry with electrothermal atomization and background correction with the Zeiman effect. The content of copper and zinc was determined by atomic absorption spectrometry with flame atomization with deuterium background correction. Mercury content – by the direct method of atomic absorption spectrometry. In all studied samples, the content of copper varied between 1.21–42.9 mg/kg, the content of zinc 17.7–75.40 mg/kg, the content of lead 0.011–1.121 mg/kg, the content of arsenic 0.0035–0.004 mg/kg, Mercury 0.005–0.051 mg/kg. The results of studies of sunflower seeds and halva for cadmium content were in the range of 0.052–0.234 mg/kg and 0.080–0.271 mg/kg. According to the obtained results, it was established that cadmium content exceeded the maximum permissible level value in five sunflower seeds and in eighteen halva samples, which is 2.7 % and 20.2 % of the total amount of the studied material. During the study of the content of inorganic pollutants Lead, Arsenic, Zinc, and Copper in sunflower seeds and halva, no violations of the maximum permissible levels were found. Regarding the analysis of meal and sunflower cake for the content of Cadmium, Lead, Arsenic, Copper, and Zinc, no violations of the MDR were detected. The contamination of seeds and halva with cadmium exceeded the legally permissible levels by 1.1 to 2.1 times. These results confirm literature data on the ability of sunflowers to accumulate cadmium, particularly in seeds. The analysis of the work demonstrates the need for more thorough and systematic control of sunflower raw materials both at the growing stage and in the process of harvesting, drying, and processing at various stages of feed and final product production.

Meet the Editors

Meet the Editors

Effect of Microwave Pre-Treatment of Biomass on the Thermal Oxidative Conversion of Biomass Blends Containing Pre-Treated and Raw Biomass of Different Origination in Terms of Processing Rate and Heat Production

In this paper, the thermochemical conversion of selectively pre-treated binary blends composed of 30% microwave (MW) pre-treated biomass pellets (wheat straw, wood) and 70% of different origin raw biomass pellets (wheat straw, wood, or peat) was performed using originally developed experimental device with a heat output up to 20 kW. Biomass pellets were pre-treated at temperatures of 200 and 275 °C using a microwave laboratory scale torrefaction of the original construction. It was established that synergistic effects of interaction between the components of binary blends promote an increase in the efficiency of their thermochemical conversion by 5.8–9.4%. It was assumed that synergistic effects of thermochemical conversion can be related to an increase in surface area and porosity of pre-treated pellets. With a focus on different steps and rates of biomass degradation and heat amounts released for different types of blends, the thermal analysis (DTG/DSC) of ground blends in the temperature range of 25–650 °C was performed in air media with the heating rate of 10 °C/min. According to the thermal analysis data, the heat energy yield of ground blends meets the requirements of linear regression based on the additivity principle and the development of synergistic effects during thermochemical conversion of ground blends was not detected.

Triple Band-stop Performance Realization Through a Single Substrate Layer Frequency Selective Surface

A single-substrate-layer Frequency Selective Surface (FSS) is designed with a 1.6 mm thick FR4 substrate for triple band-stop frequency filtering applications, that are for Bluetooth, WLAN, WiMAX, and X-band. The proposed FSS unit cell consists of two polygon loops on the front side and a square loop with four annular rings attached to its corners on the backside. The offered design covers three frequency bands: 2.3-4 GHz, 5-6 GHz, and 8-12 GHz. There are three resonances at 3.3, 5.6, and 9.9 GHz. The equivalent circuit model of the proposed structure and the formulas of the LC parameters were presented. A prototype of this structure was manufactured in size of 26 × 26 cm2 and experimentally verified in the antenna and microwave laboratory. The software used for design and simulation is HFSS from Ansys, which uses the finite element method. A comparison with similar structures was performed to demonstrate the performance of the proposed structure. The advantages of the proposed filter include adequate bandwidth, simple structure, as well as small size. In addition, it is unaffected by variant angles of incidence for TE polarization and TM polarization. Furthermore, due to its symmetrical design, it shows a polarization-independent feature. Experimental results for both polarizations verify the merits of the proposed approach, as shown before in the simulation results as well.

Использование СВЧ излучения для предынкубационной стимуляции яиц сельскохозяйственной птицы

The article describes the effect of short-term exposure to an electromagnetic field (EMF) of microwave radiation at a frequency of 2.45 GHz on the rate of development of an embryo in an egg of an agricultural bird. To carry out the experiments, a laboratory microwave setup was developed for controlled and controlled impact on the object being processed. The dielectric characteristics of protein and yolk of fertilized and non-fertilized poultry eggs were measured and analyzed, on the basis of which computer electromagnetic modeling of a microwave chamber for a laboratory pre-incubation processing unit was carried out. The influence of the microwave field on the concentration of proteins in the eggs of poultry was experimentally tested depending on the time of exposure. Keywords: EMF MICROWAVE RADIATION, ENVIRONMENTALLY FRIENDLY STIMULATION OF DEVELOPMENT

Использование СВЧ излучения для предынкубационной стимуляции яиц сельскохозяйственной птицы

The article describes the effect of short-term exposure to an electromagnetic field (EMF) of microwave radiation at a frequency of 2.45 GHz on the rate of development of an embryo in an egg of an agricultural bird. To carry out the experiments, a laboratory microwave setup was developed for controlled and controlled impact on the object being processed. The dielectric characteristics of protein and yolk of fertilized and non-fertilized poultry eggs were measured and analyzed, on the basis of which computer electromagnetic modeling of a microwave chamber for a laboratory pre-incubation processing unit was carried out. The influence of the microwave field on the concentration of proteins in the eggs of poultry was experimentally tested depending on the time of exposure. Keywords: EMF MICROWAVE RADIATION, ENVIRONMENTALLY FRIENDLY STIMULATION OF DEVELOPMENT

Using HITRAN to model opacities for planetary atmospheres: test case of microwave spectra of NH3, SO2, and PH3

ABSTRACT The latest version of the HITRAN molecular spectroscopic data base, HITRAN2020, has recently been released featuring many updates, including line-by-line broadening parameters (and their temperature dependence) appropriate for the dominant constituents of planetary atmospheres. In this work, line shape codes suitable for calculating microwave spectra have been implemented within the HITRAN Application Programming Interface (HAPI). These new additions allow for spectroscopic calculations of microwave absorbing species pertinent to current and future studies of the atmospheres of Jupiter and Venus, and more generally for the atmospheres of gas giants and rocky planets. The inversion spectrum of the NH3 molecule broadened by H2, He, and H2O dominates the microwave region of Jupiter, whereas for Venus, accurate spectroscopic data of SO2 broadened by CO2 are necessary in order to determine its significance, if any, on the reported detection of PH3 in the Venusian upper cloud deck. Comparisons have been made to available microwave laboratory opacities and the following results illustrate that HITRAN data can be used in conjunction with HAPI to reproduce the existing experimental measurements and provide reliable calculation of planetary opacities. Users should be mindful regarding selection of appropriate parameters in HITRAN and selecting suitable line shape functions in HAPI, depending on the spectral region, target molecular species, as well as ambient chemical and thermodynamic conditions.

Theoretical and experimental sensing of bone healing by microwave approach

AbstractA medical imaging system is often required to monitor bone growth or bone healing in patients. X‐ray imaging method is one of the most used imaging systems but it affects human health due to the ionizing effect of X‐rays on matter. In this paper, authors investigated the healing period of a bone structure by using electromagnetic antennas. Two different design approaches were examined which are the monopole antenna approach and the horn antenna approach with the frequency bands of 4–10 and 3–18 GHz, respectively. According to simulation results of the first scenario, radius change of a circular bone from 1 to 8 mm causes a transmission reduction from −13.5 dB to −20 dB at 7 GHz. In the second scenario, the thickness of the bone changed from 0.05 to 20 mm and the corresponding transmission value is reduced from −5 to −25 dB at 10 GHz of constant frequency. All these two approaches showed that the bone variation with time changes the transmission characteristics of detector antennas at the operating frequencies. In the last step of this study, an experimental measurement is carried out by using two opposite horn antennas and a planar bone structure in microwave laboratory. The measured results are in a good agreement with the simulated results in the second scenario. This study gives an opportunity to determine bone healing periods in medical applications by microwave techniques.

Numerical Simulation of Oil Shale Pyrolysis under Microwave Irradiation Based on a Three-Dimensional Porous Medium Multiphysics Field Model

The pyrolysis characteristics of oil shale during heat treatment dominate the oil production of kerogen. In this study, the pyrolysis characteristics of oil shale in a laboratory microwave apparatus were investigated based on a novel fully coupled three-dimensional electromagnetic-thermal-chemical-hydraulic model according to the experimental microwave apparatus. By simulating the electric field, temperature distribution, and kerogen decomposition within oil shale subjected to microwave irradiation, several parameters, including waveguide, position, and power, were successfully optimized. The results indicated that the non-uniform temperature distribution was consistent with the distribution of the electric field. Double microwave ports were more effective than single ports in terms of heating rate and temperature uniformity. There was an optimal location where the highest heating efficiency was obtained, which was on the left of the cavity center. When irradiation was conducted over a range of microwave powers, a higher power was suitable for achieving a rapid temperature increase, whereas a lower power was suitable to gain a high efficiency of the pyrolysis rate. Therefore, a variable power heating mode was introduced to decrease the heating time and improve the heat uniformity simultaneously during oil shale pyrolysis. Specifically, the secondary reactions of oil products should be maximally avoided by controlling the microwave power.

Laboratory Microwave (C-Band) Response of Compressive Stress With Partially Saturated Sandstone

Laboratory Microwave (C-Band) Response of Compressive Stress With Partially Saturated Sandstone

Randomized solid state bulk functionalization of aramid fiber pulp and its application in elastomer compositions

AbstractN‐oxydiethylene‐2‐benzothiazole sulphenamide (NOBS) dispersed in an inert (saturated main chain) rubber matrix (ethylene‐co‐propylene‐diene monomer [EPDM], as carrier to be dispersed later in a predetermined lower quantities) containing definite amount of pre‐dried aramid fiber pulp (AP) was subjected to internal thermal influence as heated through dielectric‐dielectric interaction in a laboratory microwave oven. The reactions of NOBS with aramid fiber pulp (on the surface and in the bulk) were characterized using XPS, TGA, FTIR, SEM, and mechanical properties. The objective was to confirm the efficacy of dielectric heating in situ and to promote functionality for bonding with rubber. The functionalization was considered to be provided by NOBS. One such chemical modification was found to be the generation of free ends in the AP and it was characterized by XPS. At the same time, there was no thermal degradation as confirmed from TGA studies. The rubber‐AP masterbatch (as previously prepared was dispersed) in different proportions in Butadiene‐co‐acrylonitrile rubber (NBR) and various characterizations related to plain rubber compound and in the cross linked states including fluid barrier properties and spring characteristics were found to record a significant improvement. The SEM micrographs showed that the fiber‐rubber cohesion and the rubber‐AP interaction are enhanced due to the proposed dielectric heating induced functionalization of AP.