Combined Microwave Research Articles

Breast tissue mimicking phantoms for combined ultrasound and microwave imaging

We present a new formulation for a breast tissue-mimicking phantom for combined microwave and ultrasound imaging to assist breast cancer detection. Formulations based on coconut oil, canola oil, agar and glass beads were used to mimic skin and fat tissues. First, 36 recipes were fabricated, and properties were measured to determine the relationship and possible interaction between ingredients with the ultrasound and microwave properties. Based on these results, the formulae were developed to mimic different tissues found in breast, including skin, fat, fibroglandular, and tumour tissues. All phantoms contained a base of agar and glass beads at different proportions depending on the tissue mimicked. Tumour and fibroglandular tissues were best mimicked by adding polyvinylpyrrolidone (PVP), while using coconut oil for skin and canola oil for fat produced the best results. Five final phantoms with different internal structures were fabricated and imaged using B-mode ultrasound and a microwave transmission system. Microwave permittivity maps were obtained from the microwave system and compared to ultrasound images. The structure and composition of the phantoms were all confirmed through this microwave and ultrasound imaging.

Drying characteristics and processing optimization of combined microwave drying and hot air drying of Termitomyces albuminosus mushroom

Termitomyces albuminosus (termite mushroom) is an edible fungus growing from termitaries in certain parts of China. Recently, the mushroom has gained in popularity, but due to rapid post-harvest quality decay, novel processing techniques including drying are required. This study aimed to optimize the conditions of combined microwave and hot air drying for T. albuminosus. Factors including microwave density, air temperature, and moisture content at conversion point were investigated and optimized using the drying rate, protein content, color L*, DPPH scavenging ability, rehydration ratio (RR), texture, sensory, and overall score as responses. The results showed that the overall score dried at 1.83 W/g microwave density, 60°C hot air, and 50% moisture content at conversion point were 0.675, 0.575, 0.530, respectively. The optimum conditions of combined microwave and hot air drying were microwave density 2.0 W/g, moisture content 52% at conversion point, and hot air temperature 57 respectively. The optimum conditions of combined microwave and hot air drying L* was 54.16, DPPH clearance was 91.87%, RR was 2.41, pileus chewiness was 1,587.19 g, stipe chewiness was 4,457.28 g, sensory score was 7.3, and overall score was 0.793, while the sensory quality was very high. Therefore, microwave drying followed by hot air drying is an effective, suitable method to obtain dried T. albuminosus. Practical applications Termitomyces albuminosus is also known as Termitomyces and has a similar internal fiber structure, color, and flavor as chicken. Drying is one of the most important methods for edible fungi processing and the major aim is to decrease water activity, which in turn minimizes the chemical and physical modifications during storage. The conditions of combined microwave and hot air drying for T. albuminosus were investigated and optimized using the drying rate, protein content, color L*, DPPH scavenging ability, rehydration ratio, texture, sensory, and overall score as responses. The obtained process parameters were helpful, effective, and suitable for the application of combined microwave and hot air drying technology to preserve good quality, especially for T. albuminosus.

Design of microwave hot-airflow vibrating drying equipment for initial drying and enzymatic inactivation of fresh fruits and vegetables

We developed and optimized microwave hot-airflow vibrating drying (MHAVD) equipment to improve drying efficiency and control the quality of dried agricultural products such as fruits and vegetables. Through three-dimensional modeling and finite element analysis, we simulated and demonstrated microwave source distribution modes and field intensity uniformity. We proposed two flow diversion modes, parallel deflection mode and V-shaped deflection mode, for the hot air distribution system, and we used finite element modeling to analyze them and determine the most optimal modes for use with the dryer. The microwave field strength that achieved the greatest uniformity on the surface of the material tray was used with feeding ports at X = 60 mm, Y = 80 mm, and H = 70 mm. The V-shaped deflector reduced the difference in the wind speeds on the material from 1.1 m/s to 0.36 m/s, thereby significantly increasing the uniformity, although no significant improvement in the local uniformity was noted when the parallel deflector was used. We used fresh balsam pear slices as a representative raw material to measure temperature distribution variations, moisture states, and distribution variations, and we also measured the polyphenol oxidase (PPO) enzymatic activity of the material during the primary drying with MHAVD. The results showed that balsam pear slices could be uniformly and efficiently dried in an environment below 70 °C, and the dry basis moisture content can be reduced from 15.82 to 12.35 in 12 minutes. The NMR/MRI results indicate that mainly free water in the balsam pear slices was decreased in the MHAVD process, with good moisture reduction uniformity. The PPO enzymatic activity decreased from 15.92 U/g to 0 U/g after drying. MHAVD provides a feasible method of enzyme killing, which also has the function of pre-drying for fruits and vegetables. Highlights A microwave hot-airflow vibrating drying experimental apparatus was designed Hot-air and vibrated can improve the uniformity of microwave drying There is a perfect correlation between moisture content and signal amplitude Free water can transform into immobilized water and combined water Microwave pretreatment can inactivate PPO enzyme

Preparation and Optimization Green Gel Casting Technique for Manufacturing Near-Net-Shape Ceramics Using Genetic Algorithm

Gel casting technique is a promising technology that has ability to produce near-net shape ceramics via using toxic and non-ecofriendly agents. The current work aim to develop green gel casting technique using water as a solvent, agar as a gelling agent, and the microwave thermal treatment instead of cross linker. 8mo l% Yttria stabilized zirconia was selected as a case study to produce near-net shape ceramics. The experimental work involved the preparation of Yttria stabilized zirconia nanoparticles via chemical precipitation method. The effect study of agar ratio, Yttria stabilized zirconia solid loading percent on the physical, mechanical, surface properties of the prepared ceramics and selecting of suitable casting conditions. The study has been found that the microwave thermal treatment develops thermally activated cross linking in the agar aqueous solution leading to higher glass transition temperature for agar. The green combination (agar aqueous solution and microwave treatment) can be used as alternative to (monomer, solvent, cross linker) Companion. Also, using the ultrasonic treatment can effectively eliminate needs for dispersants, also the vacuum de-airing treatment. Yttria stabilized zirconia ceramic with high dimensional accuracy, low surface roughness (Ra=2. 81 nm) can be obtained using an agar ratio of (0.4%) and solid loading of (65%). The sample can be moulded with complex shape and the green gel, also the pre-sintered body is machineable. The sintered samples have a porosity of (31%) and compressive strength of (234MPa). Regression analysis and genetic algorithm are showed that the obtained microhardness, compressive strength, and surface roughness are predictable.

Full control of superconducting qubits with combined on-chip microwave and flux lines

As the field of quantum computing progresses to larger-scale devices, multiplexing will be crucial to scale quantum processors. While multiplexed readout is common practice for superconducting devices, relatively little work has been reported about the combination of flux and microwave control lines. Here, we present a method to integrate a microwave line and a flux line into a single “XYZ line.” This combined control line allows us to perform fast single-qubit gates as well as to deliver flux signals to the qubits. The measured relaxation times of the qubits are comparable to state-of-the-art devices employing separate control lines. We benchmark the fidelity of single-qubit gates with randomized benchmarking, achieving a fidelity as high as 99.93±0.04%, and we demonstrate that XYZ lines can in principle be used to run parametric entangling gates.

Synergetic Effect of Combined CaO2 and Microwave Treatment on Waste Active Sludge Dewaterability and Organic Contaminants’ Removal

This study investigated the synergetic effect of the combined calcium peroxide (CaO2) and microwave (MW) treatment on waste active sludge dewatering properties and organic contaminants’ removal. The optimal sludge dewaterability was obtained at CaO2 (20 mg/gVSS)/MW (70°C), and the capillary suction time decreased by 52% compared with raw sludge. Further investigation indicated that total extracellular polymeric substances (EPS), tightly bound EPS, total protein, and protein present in tightly bound EPS were closely correlated with sludge dewaterability. Tryptophan, aromatic protein–like substances and humic acid–like substances were the key compounds that affect sludge dewaterability. The charge neutralization and bridge effect of cation ions were strengthened when combined with MW irradiation. In addition, it was revealed that MW facilitated CaO2 to produce more hydroxyl and superoxide anion radicals. This study confirmed CaO2/MW to be an effective way to improve sludge dewatering and remove organic pollutants from sludge.

Application of Drying Techniques on Peach Puree

In this study, six various applications were performed to dry peach puree using methods of convective drying (CD), microwave drying (MW1, MW2 and MW3) and combined convective-pulsed microwave drying (CD+MW2 and CD+MW3). Effect of drying on time, color, pH, Brix and micrographs were evaluated. The data of total drying time revealed that the maximum value was belonged to “CD” (220 min). The minimum value was obtained by “MW1” (10 min). By comparison of total color change (ΔE), the highest values were achieved with “CD+MW3”, whereas the lowest values were achieved with “MW2”. Under all drying applications, the maximum pH and Brix changes were observed with “CD+MW2”. From the microstructure, the samples to which the microwave method was applied displayed a collapsed structure as to the sample dried by the convective method.

Rapid-scan electron paramagnetic resonance using an EPR-on-a-Chip sensor.

Electron paramagnetic resonance (EPR) spectroscopy is the method of choice to investigate and quantify paramagnetic species in many scientific fields, including materials science and the life sciences. Common EPR spectrometers use electromagnets and microwave (MW) resonators, limiting their application to dedicated lab environments. Here, novel aspects of voltage-controlled oscillator (VCO)-based EPR-on-a-Chip (EPRoC) detectors are discussed, which have recently gained interest in the EPR community. More specifically, it is demonstrated that with a VCO-based EPRoC detector, the amplitude-sensitive mode of detection can be used to perform very fast rapid-scan EPR experiments with a comparatively simple experimental setup to improve sensitivity compared to the continuous-wave regime. In place of a MW resonator, VCO-based EPRoC detectors use an array of injection-locked VCOs, each incorporating a miniaturized planar coil as a combined microwave source and detector. A striking advantage of the VCO-based approach is the possibility of replacing the conventionally used magnetic field sweeps with frequency sweeps with very high agility and near-constant sensitivity. Here, proof-of-concept rapid-scan EPR (RS-EPRoC) experiments are performed by sweeping the frequency of the EPRoC VCO array with up to 400 THz s, corresponding to a field sweep rate of 14 kT s. The resulting time-domain RS-EPRoC signals of a micrometer-scale BDPA sample can be transformed into the corresponding absorption EPR signals with high precision. Considering currently available technology, the frequency sweep range may be extended to 320 MHz, indicating that RS-EPRoC shows great promise for future sensitivity enhancements in the rapid-scan regime.

Combined microwave-peanut hull based activated carbon process in the removal of oxytetracycline (OXT) from aqueous solution

Carbon materials are gaining importance in catalytic processes. In this respect, the authors studied the most important characteristics of these materials when employed as catalysts for the removal of pollutants from wastewaters.X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FT-IR) were used to characterized Charcoal Activated (CA) derived from chemical activation of peanut hulls. The key physical characteristics of the solids used in heterogeneous catalysis are the pore volume, the pore distribution, iodine number, oxygen surface groups, and the specific surface area.The combined microwave radiation-CA catalytic activity was assessed through the degradation of Oxytetracycline (OXT) under different irradiation times, initial concentrations, and acidity of the OXT solution. Furthermore, the effect of additional amounts of derived CA on the degradation was assessed.A higher removal rate of OXT contaminant by a combined MW-CA process was a synergic effect and achieved at a low concentration of OXT and pH 3 (which is the pH range of OXT solution). Furthermore, an additional amount of CA increased removal efficiency. These favorable properties make carbon a viable alternative for use as a catalyst with no residual intermediates or secondary pollution.

Microwave Atom Chip Design

We present a toolbox of microstrip building blocks for microwave atom chips geared towards trapped atom interferometry. Transverse trapping potentials based on the AC Zeeman (ACZ) effect can be formed from the combined microwave magnetic near fields of a pair or a triplet of parallel microstrip transmission lines. Axial confinement can be provided by a microwave lattice (standing wave) along the microstrip traces. Microwave fields provide additional parameters for dynamically adjusting ACZ potentials: detuning of the applied frequency to select atomic transitions and local polarization controlled by the relative phase in multiple microwave currents. Multiple ACZ traps and potentials, operating at different frequencies, can be targeted to different spin states simultaneously, thus enabling spin-specific manipulation of atoms and spin-dependent trapped atom interferometry.

Assessment of Snowfall Accumulation from Satellite and Reanalysis Products Using SNOTEL Observations in Alaska

The combination of snowfall, snow water equivalent (SWE), and precipitation rate measurements from 39 snow telemetry (SNOTEL) sites in Alaska were used to assess the performance of various precipitation products from satellites, reanalysis, and rain gauges. Observation of precipitation from two water years (2018–2019) of a high-resolution radar/rain gauge data (Stage IV) product was also utilized to give insights into the scaling differences between various products. The outcomes were used to assess two popular methods for rain gauge undercatch correction. It was found that SWE and precipitation measurements at SNOTELs, as well as precipitation estimates based on Stage IV data, are generally consistent and can provide a range within which other products can be assessed. The time-series of snowfall and SWE accumulation suggests that most of the products can capture snowfall events; however, differences exist in their accumulation. Reanalysis products tended to overestimate snow accumulation in the study area, while the current combined passive microwave remote sensing products (i.e., IMERG-HQ) underestimate snowfall accumulation. We found that correction factors applied to rain gauges are effective for improving their undercatch, especially for snowfall. However, no improvement in correlation is seen when correction factors are applied, and rainfall is still estimated better than snowfall. Even though IMERG-HQ has less skill for capturing snowfall than rainfall, analysis using Taylor plots showed that the combined microwave product does have skill for capturing the geographical distribution of snowfall and precipitation accumulation; therefore, bias adjustment might lead to reasonable precipitation estimates. This study demonstrates that other snow properties (e.g., SWE accumulation at the SNOTEL sites) can complement precipitation data to estimate snowfall. In the future, gridded SWE and snow depth data from GlobSnow and Sentinel-1 can be used to assess snowfall and its distribution over broader regions.

The Effect of Novel Microwave-Convective Drying on the Functional Properties of Dried-Pears (Pyrus communis)

Aims: The objective of this study was to investigate the impacts of combined microwave- convective drying on the quality of dried-pears. Color, bioactive compounds (total phenolics (TP) and antioxidant capacity (AC)) and textural (hardness) properties of convective (50 and 60 °C), microwave (100 and 200 W), and combined microwave-convective (100-50 °C, 200W-50 °C, 100 W-60 °C and 200 W-60 °C) dried pears were compared with the untreated pears. Results and Methods: A Konica Minolta CR-400 Chroma Meter was used to examine the color changes in dried pears. TP was measured using the Folin-Ciocalteu reagent. The free radical scavenging activity of the extract was analyzed using 1,1-dipheyl-2-picylhydrazyl (DPPH). The hardness of dried pear slices with different drying methods was obtained by a texture analyzer. The microwave- convective dried pear slices (especially at the condition of 200 W - 60 °C) showed higher preservation of bioactive compounds in addition to improved textural properties and color compared to other dried pear samples. Conclusion: Overall, combined microwave-convective drying is a promising process, as demonstrated in current research by its capability to better retain dried pear quality in terms of functional and textural properties.

Optimization of combined microwave and hot air drying technology for purple cabbage by Response Surface Methodology (RSM).

Purple cabbage is one of the world's most widely consumed vegetables with high nutritional values containing the antioxidants and anti‐inflammatory activity of anthocyanins, vitamins, and minerals. But due to rapid postharvest quality decay, novel processing techniques including drying are required. In order to determine the conditions of combined microwave and hot air drying for purple cabbage, factors affecting the drying process including microwave density, hot air temperature, and the dry base water content at conversion point were investigated using the anthocyanin content, DPPH antioxidant capacity, chewiness, △E, rehydration ratio, and average drying rate as responses. The combined drying conditions were optimized considering three independent variables at three different levels by response surface methodology. The results showed that the processing parameters of purple cabbage with combined microwave and hot air drying technology were microwave density at 2.5 W/g, moisture content of conversion point at 4.0 g/g, and hot air temperature at 55°C. Under these conditions, the anthocyanin content, DPPH antioxidant capacity, chewiness, △E, rehydration ratio, average drying rate, and overall score of the dried purple cabbage were 175.87 mg/100 g, 87.59%, 4,521.468 g, 26.5, 4.3, 0.76 g/min, and 0.785, respectively. Therefore, combined microwave and hot air drying technology is an effective, suitable method for drying purple cabbage.

Abstract 2637: The use of 3D-printed Polylactic acid scaffolds (PLA) as a substrate for growth of MCF7 human breast cancer cells

Abstract This study focuses on fabrication of large-scale tissue scaffolds from Polylactic acid (PLA) and their feasibility as a substrate for cell growth. The scaffolds were fabricated via combined additive manufacturing and microwave foaming. The benefit of this approach is the ability to generate scaffolds with specific architectures and controllable pore size and porosity. The resulting scaffolds have dual pore networks with porosity in excess of 80% which provide a pathway for both cell growth and circulation of culture media. We sought to determine the capability of these scaffolds to support attachment, growth and viability of the MCF7 human breast cancer cell line, as well as drug sensitivity. For these experiments the PLA scaffolds were sterilized in 24-well plates and 1 x 105 MCF7 cells were seeded into each well and cultured for up to 7 days. Scaffolds were then used for SEM imaging, hoescht-staining, or cell counting and viability measurements after trypsinization. Comparisons of cell numbers detached from the scaffolds vs. the remaining well suggest a proportionally small percentage of cells (less than 5%) attached to the PLA, which is not surprising since the scaffolds lack a solid bottom. However, our imaging data using hoescht-staining of PLA-attached cells pre- and post- trypsinization suggest that traditional trypsinization does not effectively detach cells from the PLA material, and therefore this method cannot be used to accurately determine the proportion of cells growing on the scaffolds. This also reveals a potential limitation for application. SEM imaging confirmed cell attachment, with cell growth in the form of sheets along the struts on the bottom layer, and clusters elsewhere with a size of around 50 micron. Analysis of viability using trypan blue exclusion shows no effect of the PLA material on cell viability. To determine the drug sensitivity of cells grown with the PLA material, we treated MCF7 cells grown in the presence or absence of oleuropein, the main phenolic compound found in olive leaves. Media was collected at 48 hours and 7 days and released LDH measured by a cytotoxicity assay. Our data showed that the PLA material itself did not increase cellular toxicity in the absence of oleuropein treatment. It also confirmed that treatment with 200 ug/ml oleuropein induces the expected cytotoxicity in MCF7 cells grown in the absence of PLA, with no significant difference in oleuropein-susceptibility for cells grown in the presence of PLA scaffolds. Together, our results suggest that PLA scaffolds can support MCF7 cell attachment and growth, with no effect on cell viability or drug-induced cytotoxicity. This provides support for the promise of PLA scaffolds for physiologically relevant cell and tissue culture work. Citation Format: Brenna McAllister, Mohammed Mustafa, Sriharsha Sundarram, Shelley A. Phelan. The use of 3D-printed Polylactic acid scaffolds (PLA) as a substrate for growth of MCF7 human breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2637.

Design of Plasmonic Catalysts Utilizing Nanostructures

This review describes the design of nanostructured plasmonic catalysts, such as nanoparticles and nanosheet morphologies, that strongly absorb visible light over a wide range of the solar spectrum due to localized surface plasmon resonance (LSPR) and application to enhanced hydrogen evolution. A new method for the synthesis of Ag nanoparticles, with color dependent on the particle size and morphology, combined microwave heating and the use of mesoporous silica materials. Further combination with Pd nanoparticles significantly enhanced the catalytic activities for hydrogen production from ammonia borane (NH3BH3) compared with the inherent Ag catalysts under both dark and visible-light irradiation conditions. We also describe the synergistic catalysis activities of plasmonic Au(core)–Pd(shell) nanoparticles supported on amine-functionalized metal-organic frameworks (MOFs) for boosting room-temperature hydrogen production from formic acid (HCOOH) under visible light irradiation. Our search for plasmonic materials based on earth abundant elements found that reduced molybdenum oxide (HxMoO3−y) nanosheet with oxygen defects and doped hydrogen displayed intense absorption in a wide range from the visible to the near-infrared region. This unique plasmonic HxMoO3−y nanosheet can enhance dehydrogenation from ammonia borane under visible light irradiation.

Combined microwave and enzymatic treatment improve the release of insoluble bound phenolic compounds from the grapefruit peel insoluble dietary fiber

Increasingly attention has been paid to the active substances in grapefruit peel. In this study, insoluble bound phenolic compounds (BP) were released from grapefruit peel insoluble dietary fiber (GP-IDF) by microwave extraction (M-BP), enzymatic hydrolysis (E-BP) and combined microwave and enzymatic treatment (ME-BP). The results showed that the yield of ME-BP was the highest (148.856 ± 0.620 GAE mg/100 g), and conditions of microwave treatment (microwave power, temperature, time) were 600 W, 85 °C, and 37 min, while that of enzymatic treatment were 8% addition, 60 °C, and 2 h. Scanning electron microscopy displayed that GP-IDF became looser by ME. ME mainly resulted in the removal of lignin in IDF from X-ray diffraction, which was consistent with FT-IR. Twenty seven BP were identified by UPLC-ESI-QTOF-MS/MS. The high content of gallic acid (42.50 ± 3.21 μg/g DW), ferulic acid (18.46 ± 1.65 μg/g DW) and protocatechuic acid (6.16 ± 0.72 μg/g DW) was quantified by LC-ESI-QqQ-MS/MS. Furthermore, ME-BP showed stronger antioxidant capacities than that of others (ABTS, oxygen and DPPH free radical scavenging ability), and showed good inhibition of α-glucosidase. Our results demonstrated that combined microwave and enzymatic treatment was an effective treatment for improving the release of BP.

Insight into the recent advances of microwave pretreatment technologies for the conversion of lignocellulosic biomass into sustainable biofuel

The utilization of renewable lignocellulosic biomasses for bioenergy synthesis is believed to facilitate competitive commercialization and realize affordable clean energy sources in the future. Among the pathways for biomass pretreatment methods that enhance the efficiency of the whole biofuel production process, the combined microwave irradiation and physicochemical approach is found to provide many economic and environmental benefits. Several studies on microwave-based pretreatment technologies for biomass conversion have been conducted in recent years. Although some reviews are available, most did not comprehensively analyze microwave–physicochemical pretreatment techniques for biomass conversion. The study of these techniques is crucial for sustainable biofuel generation. Therefore, the biomass pretreatment process that combines the physicochemical method with microwave-assisted irradiation is reviewed in this paper. The effects of this pretreatment process on lignocellulosic structure and the ratio of achieved components were also discussed in detail. Pretreatment processes for biomass conversion were substantially affected by temperature, irradiation time, initial feedstock components, catalyst loading, and microwave power. Consequently, neoteric technologies utilizing high efficiency-based green and sustainable solutions should receive further focus. In addition, methodologies for quantifying and evaluating effects and relevant trade-offs should be develop to facilitate the take-off of the biofuel industry with clean and sustainable goals.

Iron-based catalyst (Fe2-xNixTiO5) for tar decomposition in biomass gasification

In this study, a novel Fe2-xNixTiO5 catalyst for potential applications in biomass gasification gas cleaning/upgrading was investigated. The material was successfully synthesized through combined mechanical activation and microwave firing. Catalytic steam reforming was studied in a fixed bed tubular reactor, using a mixture of toluene and naphthalene as model tar compounds as well as downstream a fluidized bed gasifier. Fe2-xNixTiO5 catalyst showed high activity in converting the model compounds at temperatures higher than 700 °C. The catalyst exhibited a tar conversion of 78% at 800 °C when exposed to biomass-derived gas from a bubbling fluidized bed gasifier. Nevertheless, the catalytic activity declined with increased time on stream due to structural changes in iron active phases, caused by redox conditions of the producer gas. Furthermore, thermodynamic calculations suggest that sulfur chemisorption on the nickel surface, may also contribute to the catalyst deactivation.

Local melting and cutting of iron bulks by a synergic microwave–DC thermal skin effect

Microwaves are widely utilized in heating processes, in domestic, industrial, scientific, and medical applications. However, metal bulks (unlike metal powders or thin sheets) are commonly considered as hardly susceptible to microwave heating (due to their micrometric skin-depth, which prevents the microwave penetration into the bulk). Here, we show that adding a relatively small direct current (DC) may catalyze a localized microwave-heating (LMH) effect in the iron bulk, up to its local melting (and even further to ablation and dusty-plasma ejection). The combined DC-LMH effect is demonstrated here by cutting 8-mmØ iron rebars (made of carbon steel, with no susceptors added), which is not feasible by sole microwave or DC in these conditions. The synergic microwave and DC effect is attributed here to a combined thermal skin evolution, which jointly forms a hotspot in a mutually intensified thermal-runaway instability and deepens the microwave penetration into the iron bulk. This interpretation of the experimental findings is supported here by a simplified theoretical model of the combined microwave–DC interaction in iron, which demonstrates the thermal skin layer evolution and confirms the feasibility of a hotspot formation. The synergic DC-LMH effect may advance potential applications of microwaves in thermal processing of metals, such as melting, cutting, joining, sintering, casting, and 3D printing.

Combined Biopsy and Imaging-Guided Microwave Ablation by Using a Coaxial Guiding Needle

This article demonstrates the technique of using a coaxial guiding needle to perform combined percutaneous biopsy and microwave ablation via a single tract. From May 2019 to July 2020, 14 patients underwent combined biopsy and microwave ablation by using a coaxial guiding cannula. Tumors were in the kidney of six patients (43%), the liver of six patients (43%), and the lung in two patients (14%). The diagnostic yield of biopsy was 86% (12/14). Ablation technical success rate was 100%. In conclusion, using a coaxial guiding needle in microwave ablation and biopsy is safe and effective.