Dielectric heating for controlling field and storage insect pests in host plants and food products with varying moisture content.

At the intersection of insect control and sustainability goals, dielectric heating emerges as a promising solution. In agriculture, where insect pests can reduce agricultural yields and the nutritional quality of crops under field and storage conditions. Chemical pesticides are often used to manage pests but owing to their deleterious consequences on humans and the environment, chemical-free treatments have become the preferred option. Among the existing options, applying radio frequency (RF) and microwave energy for the purpose of dielectric heating has proven to be a successful alternative to chemical pesticides for controlling some major insect pests. This review offers an overview of dielectric heating for pest control in both storage settings and field environments, which addresses pests that impact materials with varying moisture contents (MC). The review highlights the limitation of this technology in controlling insect pests within bulk materials, leading to non-uniform heating. Additionally, it discusses the application of this technology in managing pests affecting materials with high MC, which can result in the degradation of the host material's quality. The review suggests the combination of different techniques proven effective in enhancing heating uniformity, as well as leveraging the non-thermal effects of this technology to maintain the quality of the host material. This is the first review providing an overview of the challenges associated with employing this technology against high moisture content (MC) materials, making it more advantageous for controlling storage pests. Overall, the review indicates that research should particularly emphasize the utilization of this sustainable technology against insect pests that inflict damage on high (MC) substances.

Bicolor Tuning and Hyper-Reflective Color Switching Based on Two Stacked Cholesteric Liquid Crystal Cells with Asymmetric Electrothermal Optical Responses.

We propose a double-cell cholesteric liquid crystal (CLC) device composed of a left-handed (LH) CLC cell with a pair of sheet electrodes and a right-handed (RH) CLC cell with a tri-electrode configuration characterized by a sheet electrode on the top and an interdigitated electrode on the bottom substrates. Bi-reflected color tuning and hyper-reflective color switching are revealed from this cell stack via the electrothermal control of the central wavelengths of the LH- and RH-bandgaps by voltage-induced pseudo-dielectric heating. The two CLCs are thermally sensitive and exhibit overlapped bandgaps in the field-off state with nearly identical temperature dependence, resulting in a hyper-reflective color at 720 nm at 23.4 °C and 380 nm at 29.8 °C. Upon the application of 4 Vrms at 2 MHz across the stacked device to induce pseudo-dielectric heating, two reflective colors can be resolved due to asymmetrical temperature elevations. Accordingly, the difference in wavelength between the two colors increases with increasing voltage through a series cell connection, while maintaining approximately constant via a parallel connection. This study provides a feasible pathway to developing a multifunctional device with electrothermally tunable bi-reflected and hyper-reflective states based on two conventional cell geometries, which is promising for lasers and color-related display applications.

Factors Limiting Shelf Life of a Tomato-Oil Homogenate (Salmorejo) Pasteurised via Conventional and Radiofrequency Continuous Heating and Packed in Polyethylene Bottles.

Salmorejo is a tomato-oil cold puree commercialized as a "fresh-like" product requiring mild pasteurisation and chill storage to reach a suitable shelf lifetime. The objective of this study was to study the factors which limit the shelf life of salmorejo pasteurised via conventional or radiofrequency continuous heating, packed in high-density polyethylene bottles, and kept at refrigeration. The pasteurised-chilled salmorejo reached a long shelf life (4 months) compared to that of pasteurised tomato juices or purees. Mesophilic and pathogenic bacteria were easily inhibited in this acidic product. Salmorejo mainly showed oxidative and subsequent sensory changes. Initial enzyme oxidation was associated with some adverse effects (loss of vitamin C and lipid oxidation) at the first month, although there were no sensory implications. Salmorejo remained stable at the physicochemical and sensory levels for the following 3 months, though colour and viscosity changes could be measured with instruments. Between the fourth and fifth month, salmorejo showed clear signs of deterioration, including changes in appearance (slight browning and loss of smooth surface), odour/flavour (loss of freshness and homogenisation), and consistency (thinning trend). The shelf life of salmorejo is limited by long-term oxidative deterioration and their sensory implications.

Validation of Pasteurisation Temperatures for a Tomato-Oil Homogenate (salmorejo) Processed by Radiofrequency or Conventional Continuous Heating.

Salmorejo is a viscous homogenate based on tomato, olive oil and breadcrumbs commercialised as a "fresh-like" pasteurised-chilled purée. Due to its penetration, dielectric heating by radiofrequency (RF) might improve pasteurisation results of conventional heating (CH). The objective was to validate the pasteurisation temperature (70-100 °C, at 5 °C intervals) for salmorejo processed by RF (operating at 27.12 MHz for 9.08 s) or conventional (for 10.9 s) continuous heating. The main heat-induced changes include: orangeness, flavour homogenisation, loss of freshness, thickening, loss of vitamin C and lipid oxidation. Both CH and RF equivalent treatments allowed a strong reduction of total and sporulated mesophilic microorganisms and an adequate inhibition of the pectin methylesterase, peroxidase and, to a lesser extent, polyphenol oxidase but did not inhibit the polygalacturonase enzyme. Pasteurisation at 80 °C provided a good equilibrium in levels of microbiological and enzymatic inhibition and thermal damage to the product. Increasing this temperature does not improve enzyme inactivation levels and salmorejo may become overheated. A "fresh-like" good-quality salmorejo can be obtained using either conventional or radiofrequency pasteurisers.

Microwave Regeneration and Thermal and Oxidative Stability of Imidazolium Cyanopyrrolide Ionic Liquid for Direct Air Capture of Carbon Dioxide.

Understanding the oxidative and thermal degradation of CO2 sorbents is essential for assessing long-term sorbent stability in direct air capture (DAC). The potential degradation pathway of imidazolium cyanopyrrolide, an ionic liquid (IL) functionalized for superior CO2 capacity and selectivity, is evaluated under accelerated degradation conditions to elucidate the secondary reactions that can occur during repetitive absorption-desorption thermal-swing cycles. The combined analysis from various spectroscopic, chromatographic, and thermal gravimetric measurements indicated that radical and SN 2 mechanisms in degradation are encouraged by the nucleophilicity of the anion. Thickening of the liquid and gas evolution are accompanied by 50 % reduction in CO2 capacity after a 7-day exposure to O2 under 80 °C. To prevent long exposure to conventional thermal heating, microwave (MW) regeneration of the CO2 -reactive IL is used, where dielectric heating at 80 and 100 °C rapidly desorbs CO2 and regenerates the IL without any measurable degradation.

Natural Food Resource Valorization by Microwave Technology: Purslane Stabilization by Dielectric Heating.

The application of microwave-assisted drying is a promising technique due to the features of process sustainability that are usable for responsible productions. It is largely applied for the stabilization of food products, especially in the agro-food sector. In this study, the weed Portulaca oleracea L. (purslane), with its richness in antioxidant components in addition to its recognized pharmacological properties, has been considered due to its potential to be a natural, well-accepted future food. Attention was focused on the role of the heat and mass transfer rates involved in the drying processes on the nutritional profile of the dried products. For this purpose, different drying protocols (convective, microwave irradiation, microwave-vacuum irradiation) were applied to different parts of purslane herb (apical, twigs, entire structures) and chemical characterizations were performed by a GC/MS analysis of the extracts of the dried products. The results show that microwave treatments can assure a better preservation of fatty acids such as SFAs, MUFAs, and PUFAs (which constitute over 90% of the total components in the apical part, 65% in twigs, and 85% in microwave-vacuum-dried entire purslane samples) and phytosterols (their highest preservation was found in microwave-dried twigs) compared with convective treatments. The chemical composition variability as well as treatment times depend on the drying rates (in microwave treatments, the times are on a minute scale and the rates are up to three orders of magnitude greater than convective ones), which in turn depend on the heating transport phenomena. This variability can lead towards products that are diversified by properties that transform a weed into a valorized food source.

Dynamic Permittivity Measurement of Ground-Tire Rubber (GTR) during Microwave-Assisted Devulcanization.

Many efforts are being made to find innovative ways of recycling rubber from end-of-life tires (ELTs), also called ground tire Rubber (GTR). Recycling through devulcanization allows the reintroduction of rubber back into the manufacturing industry. Such a process requires providing enough energy to break the sulfur links, while preventing damage to the polymeric chain. Microwave heating is controllable, efficient, and it does not rely on conventional heating mechanisms (conduction, convection) which may involve high heating losses, but rather on direct dielectric heating. However, to adequately control the microwave-assisted devulcanization performance, a thorough knowledge of the GTR permittivity versus temperature is required. In this work, GTR permittivity was monitored during its devulcanization. A resonant technique based on a dual-mode cylindrical cavity was used to simultaneously heat rubber and measure its permittivity at around 2 GHz. The results show sharp changes in the GTR permittivity at 160 and 190 °C. After the GTR cooled down, a shifted permittivity evidences a change in the GTR structure caused by the devulcanization process. Microwave-assisted devulcanization effectiveness is proven through time-domain nuclear magnetic resonance (NMR) measurements, by verifying the decrease in the cross-link density of processed GTR samples compared to the original sample.

A 3D LTCC-Based Ceramic Microfluidic System with RF Dielectric Heating of Liquids.

The design, fabrication and functional evaluation of the radio-frequency dielectric heating of liquids in an LTCC-based ceramic microfluidic system are described and discussed. The device, which relies on the dielectric heating of liquids, was fabricated using a low temperature co-fired ceramic (LTCC) technology. A multilayered ceramic structure with integrated electrodes, buried channels and cavities in micro and millimetre scales was fabricated. The structure with the dimensions of 35 mm × 22 mm × 2.4 mm includes a buried cavity with a diameter of 17.3 mm and a volume of 0.3 mL. The top and bottom faces of the cavity consist of silver/palladium electrodes protected with 100 µm thick layers of LTCC. The power, used to heat a polar liquid (water) in the cavity with the volume of 0.3 mL, ranges from 5 to 40 W. This novel application of RF dielectric heating could enable the miniaturization of microfluidic systems in many applications. The working principle of such a device and its efficiency are demonstrated using water as the heated medium.

Full-Scale Use of Microwave Heating in Construction of Longitudinal Joints and Crack Healing in Asphalt Pavements.

Asphalt pavement construction technology is an industry branch that undergoes constant development. Analyzing the directions of the development, one can divide it into two mainstreams: the development of roadworks equipment and the development of roadworks technology. Microwave heating technique has been mentioned in the road industry from the early '70s, but research records from practical full-scale use are very rare. This article presents the evaluation of the possible use of microwave heating technique during a particular aspect of the construction process, namely, the formation of longitudinal joints and the potential repair process of the cracked asphalt pavement. Research results showed that joints constructed using microwave-assisted heating performed the same or even better with regards to tensile characteristics comparing to other techniques. Also, the highest level of compaction was reached among the other tested techniques applied to the wearing course level. The second part of the research experiment showed the large potential of the microwave crack healing technique. The asphalt pavement was healed on its full depth of 10 cm with the single healing operation applied. Although some limitations may occur in the practical use of microwave heating, the test results suggest that it is a very promising technique and should be further developed (for, e.g., shielding concerns, electricity supply). The microwave heating technique is powered with electricity, which is important when there is a constant need for further reductions of CO2 emissions. It can be reached in parallel with clean energy or clean electricity sources.

Heating of milk powders at low water activity to 95°C for 15 minutes using hot air-assisted radio frequency processing achieved pasteurization.

Salmonella persistence in milk powders has caused several multistate foodborne disease outbreaks. Therefore, ways to deliver effective thermal treatment need to be identified and validated to ensure the microbial safety of milk powders. In this study, a process of hot air-assisted radio frequency (HARF) followed by holding at high temperatures in a convective oven was developed for pasteurization of milk powders. Heating times were compared between HARF and a convection oven for heating milk powders to a pasteurization temperature, and HARF has been shown to considerably reduce the come-up time. Whole milk powder (WMP) and nonfat dry milk (NFDM) were inoculated with a 5-serotype Salmonella cocktail and equilibrated to a water activity of 0.10 to simulate the worst case for the microbial challenge study. After heating the sample to 95°C using HARF, followed by 10 and 15 min of holding in the oven, more than 5 log reduction of Salmonella was achieved in WMP and NFDM. This study validated a HARF-assisted thermal process for pasteurization of milk powder based on previously collected microbial inactivation kinetics data and provides valuable insights to process developers to ensure microbial safety of milk powder. This HARF process may be implemented in the dairy industry to enhance the microbial safety of milk powders.

Dielectric Thermal Smart Glass Based on Tunable Helical Polymer-Based Superstructure for Biosensor with Antibacterial Property.

A dielectric thermal smart glass (DTSG) based on the dielectric heating optical (DHO) effect in tunable helical polymer-based superstructures-cholesteric liquid crystals (CLCs)-was exhibited in this study. Field-induced dielectric heating can strongly affect the orientation of liquid crystals and change its optical properties. The purpose of this research focuses on dual-frequency CLC materials characterized by their specific properties on dielectric relaxation and demonstrates their potential for antibacterial biosensor applications. The developed DTSG is driven by voltages with modulated frequencies. The principal of DTSG in transparent states are a planar (P) state and a heated planar (HP) state reflecting infrared light, operated with the voltage at low and high frequencies, respectively. The scattering states are a focal conic (FC) state and a heated FC (HFC) state, with an applied frequency near the crossover frequency. The biomolecule detection of the antibacterial property was also demonstrated. The detection limitation of the DTSG biosensor was found to be about 0.5 µg/mL. The DTSG material has many potential industrial applications, such as in buildings, photonic devices, and biosensor applications.

A microbial challenge study for validating continuous radio-frequency assisted thermal processing pasteurization of egg white powder.

Spray dried egg white powder (EWP) is traditionally processed by hot room treatment for a prolonged period of time (67 °C for 15 days) to enhance its functionality (foaming and gelling) and to improve microbial safety of EWP. Our prior research demonstrated that radio-frequency (RF) assisted thermal processing can considerably reduce the processing time, without compromising the functional properties of EWP. In this study, continuous RF processing was evaluated for pasteurization of EWP. EWP samples were inoculated with a 5-strain Salmonella cocktail or Enterococcus faecium NRRL B-2354 for the microbial challenge studies. To evaluate the inoculation method, stability and homogeneity tests were conducted for both Salmonella and E. faecium in EWP. Continuous RF heating of EWP was conducted in a 6-kW, 27.12 MHz pilot-scale parallel-plate RF heating system. RF-assisted thermal processing of EWP at 80 °C for 2 h provided >6.69 log reduction for Salmonella. E. faecium was found to be a suitable surrogate for Salmonella due to its higher resistance and similar inactivation kinetics during RF heating of EWP. The validated RF-assisted thermal process can be scaled up for use in the egg industry.

A novel dual mode X-band EPR resonator for rapid in situ microwave heating.

A unique dual mode X-band Continuous Wave (CW) EPR resonator designed for simultaneous EPR measurement and rapid microwave (MW) induced sample heating is described. Chemical reactions subjected to a flow of energy and matter can be perturbed away from the thermodynamic equilibrium by imposing a rapid shock or physical change to the system. Depending on the magnitude of the perturbation, these changes can dictate the subsequent evolution of the entire system, allowing for instance to populate non-equilibrium reactive intermediate states. Temperature jump (T-jump) experiments are a common method to achieve such perturbations. Most T-jump experiments are based on Joule Heating methods or IR lasers. Here we demonstrate the principle of rapid sample heating based on microwaves. The benefits of MW heating include (i) rapid and efficient heating (i.e. using a tuned resonant cavity, >99% efficient power transfer to the sample can be achieved), and (ii) volumetric heating (i.e. the entire sample volume rises in temperature at once, since heat is generated in the sample instead of being transferred to it). Accordingly, the key concept of the design is the use of a cavity resonator allowing EPR detection (at 9.5 GHz) and simultaneous sample heating (at 6.1 GHz). Temperature increments of 50 °C within a few seconds are possible. This is evidenced and illustrated here by probing the temperature-induced variation of the rotational dynamics of 16-doxyl stearic acid methyl ester (16-DSE) spin probe grafted on the surface of sodium dodecyl sulphate (SDS) micelles in water, as well as copper (II) acetylacetonate in chloroform. Rapid changes in the rotational dynamics of the paramagnetic centres provide direct evidence for the in situ and simultaneous EPR measurement-heating capabilities of the resonator. Improvements afforded by the use of pulsed MW sources will enable faster heating time scales to be achieved. In the longer term, this current study demonstrates the simple and direct possibilities for using MW heating as a means of performing T-jump experiments.

Radiofrequency pasteurization process for inactivation of Salmonella spp. and Enterococcus faecium NRRL B-2354 on ground black pepper.

Salmonella persistence in ground black pepper has caused several foodborne outbreaks and created public concern about the safety of low water activity (aw) foods. In this study, radiofrequency (RF) processing was evaluated for pasteurization of ground black pepper. Stability and homogeneity tests were done for both Salmonella spp. and E. faecium during moisture equilibration before RF heating to evaluate the inoculation method. Moisture content of samples were conditioned such that the final moisture content after RF heating reached the optimal storage moisture. RF heating was shown to provide more than 5.98 log CFU/g reduction for Salmonella spp. and the reduction of 3.89 log CFU/g for E. faecium with a 130 s of treatment time. The higher thermal resistance of E. faecium indicated its suitability as surrogate for Salmonella spp. during RF heating of ground black pepper. Piperine, total phenolics, volatile compounds, and antioxidant activity were assessed as quality parameters for ground black pepper. The results demonstrated that the RF processing provided effective inactivation of Salmonella spp. with insignificant (p > 0.05) quality deterioration.

Dielectric and Resistive Heating of Polymeric Media: Toward Remote Thermal Activation of Stimuli-Responsive Soft Materials.

Stimuli-responsive soft materials are becoming increasingly important in a wide range of contemporary technologies, and methods by which to promote thermal stimulation remotely are of considerable interest for controllable device deployment, particularly in inaccessible environments such as outer space. Until now, remote thermal stimulation of responsive polymers has relied extensively on the use of nanocomposites wherein embedded nanoparticles/structures are selectively targeted for heating purposes. In this study, an alternative remote-heating mechanism demonstrates that the dielectric and resistive thermal losses introduced upon application of an alternating current generate sufficient heat to raise the temperature of a neat polyimide by over 70 °C within ≈10 s. Thermal imaging is used here to measure current-induced temperature changes of polymeric media, and a proposed analytical model yields predictions that compare reasonably well with experimental data, confirming that such remote heating is viable. Conditions permitting a shape-memory polymer possessing a melting transition and susceptible to dielectric actuation to achieve continuous electrostrain-temperature cycling are identified.

Radio-Frequency Processing for Inactivation of Salmonella enterica and Enterococcus faecium NRRL B-2354 in Black Peppercorn.

Several Salmonella outbreaks linked to black pepper call for effective inactivation processes, because current decontamination methods result in quality deterioration. Radio-frequency (RF) heating provides a rapid heating rate and volumetric heating, resulting in a shorter come-up time. This allows for choosing a high-temperature and short-time combination to achieve the desired inactivation with minimal quality deterioration. The objectives of this study were to evaluate RF heating for inactivation of Salmonella enterica and Enterococcus faecium in black peppercorn and evaluate quality changes of RF-treated black peppercorn. Black peppercorns were inoculated with a five-strain cocktail of Salmonella or E. faecium to attain initial population levels of 6.8 and 7.3 log CFU/g, respectively, and were then adjusted to a moisture content of 12.7% (wet basis) and a water activity of 0.60 at room temperature. A stability test was performed to quantify the microbial reduction during inoculation and equilibration before RF heating inactivation. During RF heating, the cold spot was determined to be at the center on the top surface of the treated sample. In addition to inoculating the entire sample, an inoculated packed sample was placed at the cold spot of the tray. An RF heating time of 2.5 min provided a 5.31- and 5.26-log CFU/g reduction in the entire sample contained in the tray for Salmonella and E. faecium, respectively. Color parameters (L*, a*, b*), piperine content, total phenolics, scavenging activity, and most of the volatile compounds of 2.5-min RF-treated samples were not significantly different from those of the control samples. These data suggest that RF heating is a promising thermal inactivation treatment for Salmonella without significant quality deterioration, and E. faecium seems to be a suitable surrogate for Salmonella to validate the efficacy of RF heating of black peppercorn.

Review on Microwave-Matter Interaction Fundamentals and Efficient Microwave-Associated Heating Strategies.

Microwave heating is rapidly emerging as an effective and efficient tool in various technological and scientific fields. A comprehensive understanding of the fundamentals of microwave-matter interactions is the precondition for better utilization of microwave technology. However, microwave heating is usually only known as dielectric heating, and the contribution of the magnetic field component of microwaves is often ignored, which, in fact, contributes greatly to microwave heating of some aqueous electrolyte solutions, magnetic dielectric materials and certain conductive powder materials, etc. This paper focuses on this point and presents a careful review of microwave heating mechanisms in a comprehensive manner. Moreover, in addition to the acknowledged conventional microwave heating mechanisms, the special interaction mechanisms between microwave and metal-based materials are attracting increasing interest for a variety of metallurgical, plasma and discharge applications, and therefore are reviewed particularly regarding the aspects of the reflection, heating and discharge effects. Finally, several distinct strategies to improve microwave energy utilization efficiencies are proposed and discussed with the aim of tackling the energy-efficiency-related issues arising from the application of microwave heating. This work can present a strategic guideline for the developed understanding and utilization of the microwave heating technology.

Potential use of microwave treatment on fresh-cut carrots: physical, chemical and microbiological aspects.

BACKGROUND: The effect of microwave treatments (900 and 750 W for 45 and 60 s) on the microbial, physicochemical and sensory properties of fresh-cut carrot slices and the contents of several bioactive compounds was studied. Carrot samples were stored for 7 days at 5 °C. RESULTS: The microwaving of fresh-cut carrots reduced the initial respiration rate (8.6 CO2 mL kg(-1) h(-1)) by 55-74% compared with untreated samples, although the rates then increased during storage. The initial pH (6.7), titratable acidity (0.036%), soluble solid content (8.2 °Brix) and shelf-life of the samples did not differ greatly from those of the untreated samples. Microwaving prevented the incipient whitening and surface dryness during storage. In general, no significant changes in phenylalanine ammonia lyase activity (5.5 µmol t-cinnamic acid kg(-1) h(-1)), total phenolics (TP, 81.3 mg chlorogenic acid equivalent kg(-1) fresh weight (FW)) or total antioxidant capacity (TAC, 74.2 µmol Trolox equivalent kg(-1) FW) were observed on the processing day or over storage. However, the mildest treatment (750 W for 45 s) caused TP and TAC enhancements of 118 and 394% respectively after 7 days of shelf-life. Microwave treatments reduced the initial microbial loads of the samples by up to 1.8 log units, although their microbial growth was greater than that of the untreated samples throughout storage. CONCLUSION: Mild microwave treatments such as 750 W/45 s and 750 W/60 s are a good sustainable alternative to the use of NaOCl; however, combining them with other sanitizing techniques is needed to control microbial growth throughout the shelf-life of fresh-cut carrot slices.

Impact of Radio Frequency, Microwaving, and High Hydrostatic Pressure at Elevated Temperature on the Nutritional and Antinutritional Components in Black Soybeans.

In this study, the effects of high hydrostatic pressure (HHP) at elevated temperature (60 °C) and 2 dielectric heating (DH) methods (radio frequency [RF], and microwaving [MW]) on the nutritional compositions and removal of antinutritional factors in black soybeans were studied. Each treatment caused <2% reduction in protein, and 3.3% to 7.0% decline in total amino acid content. However, the proportion of essential amino acid slightly increased in DH treated samples. The treatment decreased fat content (14.0% to 35.7%), but had small influence on fatty acid proportion. Antinutritional factors including trypsin inhibitor, tannins, saponins, and phytic acid were all declined by the 3 treatments, and DH treatment was generally more efficient. The most abundant saponins was decreased >22% in DH treated samples. MW and HHP led to higher in vitro protein digestibility, RF and MW promoted protein aggregation from atomic force microscope topography, but HHP caused more damages on protein subunits as seen from SDS-PAGE image.

Frequency swept microwaves for hyperfine decoupling and time domain dynamic nuclear polarization.

Hyperfine decoupling and pulsed dynamic nuclear polarization (DNP) are promising techniques to improve high field DNP NMR. We explore experimental and theoretical considerations to implement them with magic angle spinning (MAS). Microwave field simulations using the high frequency structural simulator (HFSS) software suite are performed to characterize the inhomogeneous phase independent microwave field throughout a 198GHz MAS DNP probe. Our calculations show that a microwave power input of 17W is required to generate an average EPR nutation frequency of 0.84MHz. We also present a detailed calculation of microwave heating from the HFSS parameters and find that 7.1% of the incident microwave power contributes to dielectric sample heating. Voltage tunable gyrotron oscillators are proposed as a class of frequency agile microwave sources to generate microwave frequency sweeps required for the frequency modulated cross effect, electron spin inversions, and hyperfine decoupling. Electron spin inversions of stable organic radicals are simulated with SPINEVOLUTION using the inhomogeneous microwave fields calculated by HFSS. We calculate an electron spin inversion efficiency of 56% at a spinning frequency of 5kHz. Finally, we demonstrate gyrotron acceleration potentials required to generate swept microwave frequency profiles for the frequency modulated cross effect and electron spin inversions.