RF Applications Research Articles

Lessons from ablation responses to preferential wavefront in typical atrial flutter.

The heterogeneous conduction properties through the cavotricuspid isthmus (CTI) in typical atrial flutter (AFL) have not yet been well elucidated. We sought to investigate preferential conduction through the CTI and the efficacy of ablation targeting preferential wavefront (PW) guided by ultra-high-resolution mapping. In retrospective study, 28 patients were enrolled. Wavefront propagation patterns through the CTI and ablation responses at the location of PW were evaluated. In the following prospective study, 23 patients with predominant PW across the CTI were enrolled and assigned to the arm of PW prior ablation and the arm of conventional ablation. Five activation patterns were noticed in the retrospective study. The termination sites were exactly located at the PW in 18 of 28 patients (64.3%). The width of the PW in direct termination group was significantly narrower than that in the CL prolongation before termination group (16.6 ± 1.0mm vs. 23.3 ± 3.4mm, respectively, p = 0.025). In the prospective study, the voltage of PW region was significantly higher than non-PW regions both from unipolar and bipolar mapping. 21 of 23 patients (91.3%) were terminated at PW. AFL could no longer be induced immediately after termination. The time from radiofrequency application to AFL termination and to achieve bidirectional conduction block was significantly shorter in PW prior ablation arm than that in conventional ablation group (p < 0.05). Ablation targeting the PW first could be more efficient to terminate typical AFL and to achieve the endpoint of bidirectional conduction block.

Piezoelectrically and Capacitively Transduced Hybrid MEMS Resonator with Superior RF Performance and Enhanced Parasitic Mitigation by Low-Temperature Batch Fabrication

This study investigates a hybrid microelectromechanical system (MEMS) acoustic resonator through a hybrid approach to combine capacitive and piezoelectric transduction mechanisms, thus harnessing the advantages of both transducer technologies within a single device. By seamlessly integrating both piezoelectric and capacitive transducers, the newly designed hybrid resonators mitigate the limitations of capacitive and piezoelectric resonators. The unique hybrid configuration holds promise to significantly enhance overall device performance, particularly in terms of quality factor (Q-factor), insertion loss, and motional impedance. Moreover, the dual-transduction approach improves the signal-to-noise ratio and reduces feedthrough noise levels at higher frequencies. In this paper, the detailed design, complex fabrication processes, and thorough experimental validation are presented, demonstrating substantial performance enhancement potentials. A hybrid disk resonator with a single side-supporting anchor achieved an outstanding loaded Q-factor higher than 28,000 when operating under a capacitive drive and piezoelectric sense configuration. This is comparably higher than the measured Q-factor of 7600 for another disk resonator with two side-supporting anchors. The hybrid resonator exhibits a high Q-factor at its resonance frequency at 20 MHz, representing 2-fold improvement over the highest reported Q-factor for similar MEMS resonators in the literature. Also, the dual-transduction approach resulted in a more than 30 dB improvement in feedthrough suppression for devices with a 500 nm-thick ZnO layer, while hybrid resonators with a thicker piezoelectric layer of 1300 nm realized an even greater feedthrough suppression of more than 50 dB. The hybrid resonator integration strategy discussed offers an innovative solution for current and future advanced RF front-end applications, providing a versatile platform for future innovations in on-chip resonator technology. This work has the potential to lead to advancements in MEMS resonator technology, facilitating some significant improvements in multi-frequency and frequency agile RF applications through the original designs equipped with integrated capacitive and piezoelectric transduction mechanisms. The hybrid design also results in remarkable performance metrics, making it an ideal candidate for integrating next-generation wireless communication devices where size, cost, and energy efficiency are critical.

Combined approach of high-power and very high-power, short-duration ablation in superior vena cava isolation.

The effectiveness and safety of 50 W, high-power, short-duration (HPSD) ablation in superior vena cava isolation (SVCI) for patients with atrial fibrillation (AF) have been reported. However, the acute outcomes of SVCI combined with 90 W/4 s, very high-power, short-duration (vHPSD) ablation remain unknown. In this study, we aimed to investigate a novel approach that combines 50 W-HPSD and 90 W/4 s-vHPSD ablation in SVCI and to elucidate the characteristics, outcomes, and safety of this approach by comparing SVCI with conventional ablation index (AI)-guided middle-power, middle-duration (MPMD) ablation. Overall, 126 patients who underwent AF ablation with SVCI using the QDOT MICROTM catheter were retrospectively reviewed; one group underwent SVCI with a combined approach of HPSD and vHPSD ablation (50 W/90 W group, n = 73) and another group underwent AI-guided MPMD ablation (30-40 W group, n = 53). This study compared the procedural details, radiofrequency (RF) ablation profiles, and complications. The RF settings used in the 50 W/90 W group were 50 W/7 s for the lateral segment close to the phrenic nerve and 90 W/4 s for the nonlateral segment. The 50 W/90 W group required a significantly shorter procedural time (3.2 vs. 5.9 min, p < .001), shorter RF duration (42.0 vs. 162.0 s, p < .001), and lower RF energy (2834 vs. 5480 J, p < .001) than the 30-40 W group. Procedural success, first-pass SVCI, number of RF applications, and SVC reconnection after isoproterenol loading were comparable between the groups. The maximum tip-electrode temperature of the multi-thermocouple system was significantly higher in the 50 W/90 W group than in the 30-40 W group (50.0°C vs. 47.0°C, p < .001). No complications, such as phrenic nerve injury or bleeding requiring transfusion, were observed in either group. The combined approach of 50 W/7 s-HPSD and 90 W/4 s-vHPSD ablation resulted in successful and safe SVCI with shorter procedural time, shorter RF duration, and lower RF energy.

Design and investigation of gaussian doped junction free SMDG and TMDG-TFET for analog/RF applications

This research investigates four variants of Gaussian Doped (GD) Double Gate Single Material and Tri-Material Junction-Free Tunnel-Field-Effect-Transistors (GD-DG-JF-TFETs) to optimize their performance in analog and RF applications. The analysis is conducted using the Sentaurus Synopsis TCAD simulation tool, reveals a Subthreshold Swing (SS) as low as 38 mV/dec, exceptionally higher cut-off-frequency (f t ) and maximum-oscillation-frequency ( fmax ) of 516 GHz and 895 GHz, respectively. The proposed TMDG-JF-TFET enhances band-to-band tunneling between the drain and source regions, resulting in an extremely low-off-state-current (I off) of 9.6 fA and large-on-state current (I ON) of 6.7 mA in Permittivity of high-k (HfO 2 = 25) and low-k (SiO 2 = 3.8) based structures.Compared to conventional SMDG technologies, the TMDG structures exhibits 36% reduction in SS, a 16% improvement in f t , an 18% enhancement in fmax and 17% increase in I ON. These improvements demonstrate that TMDG-based TFETs are superior devices for ultra-low-power-integrated-circuit-applications.

Investigations on Cylindrical Surrounding Double-Gate (CSDG) MOSFET using AlxGa1-xAs/InP: Pt with La2O3 oxide layer for fabrication.

The Cylindrical Surrounding Double-Gate MOSFET has been designed using Aluminium Gallium Arsenide in its arbitrary alloy form alongside Indium Phosphide with Lanthanum Dioxide as a high-ƙ dielectric material. The heterostructure based on the AlxGa1-xAs/InP: Pt has been used in the design and implementation of the MOSFET for RF applications. Platinum serves as the gate material, which has higher electronic immunity toward the Short Channel Effect and highlights semiconductor properties. The charge buildup is the main concern in the field of MOSFET design when two different materials are considered for fabrication. The usage of 2 Dimensional Electron Gas has been outstanding in recent years to help the electron buildup and charge carrier accumulation in the MOSFETs regime. Device simulation used for the smart integral systems is an electronic simulator that uses the physical robustness and the mathematical modeling of semiconductor heterostructures. In this research work, the fabrication method of Cylindrical Surrounding Double Gate MOSFET has been discussed and realized. The scaling down of the devices is essential to reduce the area of the chip and heat generation. By using these cylindrical structures, the area of contact with the circuit platform is reduced since the cylinder can be laid down horizontally. The coulomb scattering rate is observed to be 18.3 % lower than the drain terminal when compared to the source terminal. Also, at x = 0.125 nm, the rate is 23.9 %, which makes it the lowest along the length of the channel; at x = 1 nm, the rate is 1.4 % lesser than that of the drain terminal. A 1.4 A/mm2 high current density had been achieved in the channel of the device, which is significantly larger than comparable transistors. The conventional transistor occupies a larger area than the proposed cylindrical structures transistor and is also efficient in RF applications.

A new experiment to enable rapid systematic investigations of flux trapping dynamics for superconducting radio-frequency cavity applications.

Many modern accelerators rely on superconducting radio-frequency (SRF) cavities to accelerate particles. When these cavities are cooled to the superconducting state, a fraction of the ambient magnetic field (e.g., Earth's magnetic field) may be trapped in the superconductor. This trapped flux can significantly increase the power dissipation of the SRF cavities. It is, therefore, crucial to understand the underlying mechanism of how magnetic flux is trapped and what treatments and operating conditions can reduce the flux-trapping efficiency. A new experiment was designed that enables a systemic investigation of flux trapping. It allows for independent control of cooldown conditions, which might have an influence on flux trapping: temperature gradient across the superconductor during cooldown, cooldown rate, and ambient magnetic field. For exhaustive studies, the setup was designed for quick thermal cycling, permitting up to 300 superconducting transitions in one day. In this paper, the setup and operation is described in detail and an estimation of the measurement errors is given. Exemplary data are presented to illustrate the efficacy of the system.

Parametric Analysis of Indium Gallium Arsenide Wafer-based Thin Body (5 nm) Double-gate MOSFETs for Hybrid RF Applications.

The electrical behavior of a high-performance Indium Gallium Arsenide (In- GaAs) wafer-based n-type Double-Gate (DG) MOSFET with a gate length (LG1= LG2) of 2 nm was analyzed. The relationship of channel length, gate length, top and bottom gate oxide layer thickness, a gate oxide material, and the rectangular wafer with upgraded structural characteristics and the parameters, such as switch current ratio (ION/IOFF) and transconductance (Gm) was analyzed for hybrid RF applications. This work was carried out at 300 K utilizing a Non-Equilibrium Green Function (NEGF) mechanism for the proposed DG MOSFET architecture with La2O3 (EOT=1 nm) as gate dielectric oxide and source-drain device length (LSD) of 45 nm. It resulted in a maximum drain current (IDmax) of 4.52 mA, where the drain-source voltage (VDS) varied between 0 V and 0.5 V at the fixed gate to source voltage (VGS) = 0.5 V. The ON current(ION), leakage current (IOFF), and (ION/IOFF) switching current ratios of 1.56 mA, 8.49Í10-6 μA, and 18.3Í107 μA were obtained when the gate to source voltage (VGS) varied between 0 and 0.5 V at fixed drain-source voltage (VDS)=0.5V. The simulated result showed the values of maximum current density (Jmax), one and twodimensional electron density (N1D and N2D), electron mobility (μn), transconductance (Gm), and Subthreshold Slope (SS) are 52.4 μA/m2, 3.6Í107 cm-1, 11.36Í1012 cm-2, 1417 cm2V-1S-1, 3140 μS/μm, and 178 mV/dec, respectively. The Fermi-Dirac statistics were employed to limit the charge distribution of holes and electrons at a semiconductor-insulator interface. The flat-band voltage (VFB) of - 0.45 V for the fixed threshold voltage greatly impacted the breakdown voltage. The results were obtained by applying carriers to the channels with the (001) axis perpendicular to the gate oxide. The sub-band energy profile and electron density were well implemented and derived using the Non-Equilibrium Green's Function (NEGF) formalism. Further, a few advantages of the proposed heterostructure-based DG MOSFET structure over the other structures were observed. This proposed patent design, with a reduction in the leakage current characteristics, is mainly suitable for advanced Silicon-based solid-state CMOS devices, Microelectronics, Nanotechnologies, and future-generation device applications.

Radiofrequency Lesion in the Atrial Wall: How Variable Is It? 9.4 Tesla MRI Analysis of Radiofrequency Lesion Volume in a Swine Model.

Background/Objectives: Most data on radiofrequency (RF) effects come from ex vivo or in vitro studies that quantify lesions using width and/or depth, while electrophysiologists use manufacturers' indirect indices. The objective of this study was to evaluate RF lesion volume by high-resolution MRI of excised lesions in an in vivo porcine model, comparing a low-energy long-duration (LE) (20 W, 50 s) RF application strategy with a high-energy short-duration (HE) (50 W, 20 s) one. Methods: Eighteen piglets were divided into LE (n = 9) and HE groups (n = 9). RF applications were performed at four locations in both atria. Animals were sacrificed after 5-7 days, and RF lesion specimens were excised, fixed, and analyzed by 9.4 Tesla MRI. RF lesion volume, variability (variance), depth, and any extracardiac lesions were compared between the groups. Results: Seventy RF applications were performed (36 LE, 34 HE). MRI analyzed 26 LE and 28 HE samples. The HE group showed 35% higher volume than the LE group (100.2 mm3 (±81.2) in LE vs. 178.3 mm3 (±163.7) in HE, p = 0.033). RF volume variance was 6.6 mm3 in LE and 40.3 mm3 in HE. The HE group had more complications (seven vs. zero, p = 0.02) and extracardiac lesions (18 vs. 14, p = 0.613). Conclusions: There was large and unpredictable variability in RF injury on the atrial wall, even under controlled conditions, which could explain arrhythmia recurrences. The greatest lesion variability was found during HE applications. The dose/effect relationship of RF needs careful study for treating cardiac arrhythmias.

Effect of capacitive radiofrequency on adipose tissue of the abdominal region

Objectives: To evaluate histological changes in the adipose tissue after capacitive radiofrequency (RF) stimulation (thermotherapy). Methods: This is a case series study (n=5). The volunteers received in the right infraumbilical abdominal region a single application of capacitive RF (BTL-6000 TR-Therapy Pro®), with a frequency of 480 to 520KHz, power of 150 W for 10 minutes (2 minutes per head area, 50mm in diameter). The epidermal temperature was above 40°C, and, the left side was used as control. After 30 days, an average, tissue sample was collected for histological analysis and stained with hematoxylin and eosin. Statistical analysis was performed using the SPSS program (version 20), with a significance level of 95%, and the adipocyte count was performed using Image J®. This study was registered with the XXXX Ethics Committee n. 3,461,688, Jul/12/19 and, the number of clinical trial registration was NCT04182542. Results: The number of adipocytes on the treated side was 41.2 ± 2.0 per field and, in the control side was 36.6 ± 2.0 per field, with a significant difference (p=0.009), because of the size of adipocytes being smaller on the side treated. Conclusion: Radiofrequency can lead to morphological changes in adipocytes in the abdominal region with an important reduction in their size.

Transcoronary guidewire ablation with radiofrequency in a porcine animal model.

Transcoronary ablation of septal hypertrophy (TASH) and surgical myectomy are the recommended treatment options for patients with hypertrophic obstructive cardiomyopathy refractory (HOCM) when conventional drug treatment is not sufficient. We describe the application of radiofrequency (RF) energy via coronary guidewires in an animal model for selective occlusion of coronary side branches that mimics the principle of TASH. Transcoronary guidewire ablation of coronary vessels was performed in 5 adult pigs under general anaesthesia in an animal cathlab after successful bench testing of the ablation settings. After assessing transcoronary pacing parameters, RF energy was delivered via coronary guidewires insulated by coating or by a monorail balloon and positioned in different coronary side branches. Occlusion or patency of the specific coronary side branch was documented by coronary angiography after RF delivery. After the transcoronary RF ablation, the intended occlusion of the coronary vessel (thrombolysis in myocardial infarction [TIMI]-0 or TIMI-1 flow) could be verified by angiography in 82% of the septal branches attempted and 79% of the epicardial branches. The mean ablation duration was 10.3 seconds at 20-W power with an initial impedance of 176 ± 31 Ώ. No unintended occlusion of the main vessels occurred in any case. RF ablation via coronary guidewires is a feasible method for inducing an acute occlusion of coronary vessels and may change the interventional therapy of HOCM if the current limitations of this technique are overcome.

The benefits of ablation using TactiFlex compared with TactiCath in an ex vivo model: a face-to-face experimental comparison study.

TactiFlex is a next-generation catheter that is being used increasingly in ablation-treatment strategies. The purpose of this study was to investigate the differences in ablation lesions when the ablation power, time, and perfusion flow are varied with TactiFlex and TactiCath catheters. The TactiFlex and TactiCath catheters were contacted perpendicularly/obliquely/parallel to the swine myocardium at varying powers (30, 40, and 50 W), time points (10, 15, 20, 25, 30, and 40s), and forces (5, 10, 15, 20, and 30g); the depth, width, and area of each lesion were measured, and the number of steam pops that occurred was counted. A total of 672 (336 lesions for each catheter) radiofrequency (RF) energy applications were delivered and 648 lesions were analyzed, excluding steam pops. The surface area and volume increased significantly with an increasing contact force for the TactiCath. The TactiCath lesions were significantly deeper than those for TactiFlex in most groups with the same power and seconds. The surface area was significantly larger when the catheters were contacted obliquely/parallel to the myocardium than perpendicularly using TactiCath, whereas the difference was less significant in the case of TactiFlex. In a 10-g contact force ablation experiment, TactiFlex did not cause pops, but TactiCath caused pops in 9.8% of cases. The TactiFlex lesions were shallower than those of TactiCath. However, TactiFlex catheters reduced the steam pops during RF applications. Those data should help clinicians understand the characteristics of the catheters and develop adequate strategies.

Can the QRS morphology of outflow tract ventricular arrhythmia change when right bundle branch block emerges during sinus rhythm?

QRS morphology can change during ventricular arrhythmias (VAs) with the appearance of bundle branch block (BBB). We retrospectively investigated 195 consecutive patients who underwent an initial ablation of VA. The study inclusion criteria were VAs that were successfully ablated in the outflow tract (OT) and in whom right bundle branch block (RBBB) was induced by catheter manipulation close to the His bundle area during sinus rhythm, before any radiofrequency application. We analyzed the QRS morphology of the VAs with and without RBBB during sinus beats. Twenty-four patients (age 59±17 years, female 14) developed RBBB at some point during their procedure. The successful ablation sites of the VAs were the right ventricular outflow tract (RVOT) in 12 patients, pulmonary artery in one, left coronary cusp in five, right coronary cusp in three, right-left cusp junction in two, and great cardiac vein in two. QRS-morphology change was observed in five (20%) cases. The successful ablation sites in that group were the left coronary cusp in three cases, right coronary cusp in one, and RVOT septum in one. The QRS duration of the VAs increased during RBBB. There are some cases of OT-VAs in which the QRS waveform changes with the appearance of catheter induced RBBB. We need to be aware that when QRS morphology changes during an OT-VA ablation, it does not necessarily mean that the origin or exit of the VA has changed.

General Anesthesia Improves Efficiency of High-Power Short-Duration Catheter Ablation for Atrial Fibrillation: Comparison with Mild Conscious Sedation.

Atrial fibrillation (AF) is the most common cardiac arrhythmia globally. High-power, short-duration radiofrequency (RF) catheter ablation (CA) for AF has recently emerged, reducing ablation times and enhancing patient tolerability with comparable efficacy and safety. While the benefits of general anesthesia (GA) for standard-power, standard-duration CA are well-established, data comparing GA to mild conscious sedation (MCS) for high-power, short-duration CA are limited. We included patients undergoing high-power, short-duration CA for AF under GA (group 1) or MCS (group 2). Procedural characteristics, success rates, and mid-term outcomes were compared. In total, 131 patients, 47 in the GA group and 84 in the MCS group, were included. CA was performed for paroxysmal AF in 34 patients in group 1 (72.3%) and 68 patients in group 2 (80.9%). We found lower a mean total procedure time (100 [90-120] vs. 160 [130-180] min, p < 0.0001), lower radiation exposure (932.5 [625-1716] vs. 2445 [1228-4791] μGy, p < 0.0001 and 4.5 [3-7.1] 7.3 [4.2-13.5] min, p = 0.0003) and fewer RF applications (71 [54.8-83.8] vs. 103 [88.5-120.5], p < 0.0001) in the GA group. No major complications occurred. The 6-month AF recurrence rate was comparable between the groups (21.2% vs. 33.3%, p = 0.15). In patients undergoing high-power, short-duration RFCA for AF, the use of GA is associated with better procedural efficiency while simultaneously associated with an early recurrence rate comparable to MCS.

Application of radio frequency energy in processing of fruit and vegetable products.

Thermal processing is commonly employed to ensure the quality and extend the shelf-life of fruits and vegetables. Radio frequency (RF) heating has been used as a promising alternative treatment to replace conventional thermal processing methods with advantages of rapid, volumetric, and deep penetration heating characteristics. This article provides comprehensive information regarding RF heating uniformity and applications in processing of fruit and vegetable products, including disinfestation, blanching, drying, and pasteurization. The dielectric properties of fruits and vegetables and their products have also been summarized. In addition, recommendations for future research on RF heating are proposed to enhance practical applications for fruits and vegetables processing in future.

Thermal analysis of GaN HEMTs using nongray multi-speed phonon lattice Boltzmann method under Joule heating effect

Gallium Nitride (GaN) high electron mobility transistors (HEMTs) exhibit superior electrical properties for power and radio frequency applications, but performance is compromised by localized Joule heating, increasing channel temperatures. Precise thermal analysis during design is essential for optimizing device architecture and management strategies. Traditional methods like the Fourier heat diffusion equation (HDE) and the phonon lattice Boltzmann method (PLBM) with the D2Q8 scheme inadequately model phonon ballistic transport at high Knudsen numbers. This study introduces a nongray multi-speed PLBM integrated with the drift-diffusion model to analyze electro-thermal processes in GaN HEMTs. Validated through simulations of thermal conductivities in two-dimensional GaN thin films, the approach examines internal temperature rise in GaN HEMTs under different gate voltages, comparing results with HDE and gray BTE models, and emphasizing the need for non-Fourier effects in thermal analysis. It also evaluates the impact of GaN layer thickness on temperature distribution, providing a robust solution for thermal analysis in GaN HEMTs and other field-effect transistors.

Concurrent Multifrequency Complex to Real Impedance Matching Network for RF Applications

This paper presents a novel technique for matching complex loads to a real source concurrently at uncorrelated frequencies under any load conditions. In the proposed method, a branched stub adds susceptances to the load admittances such that the adjusted loads for all the frequencies can be shifted to g = 1 circle using a single series transmission line; hence matching the real part of the admittances. The left-over susceptance is cancelled through another branched stub. Its adaptability allows it to increase the number of bands by adding transmission lines to the branched stubs. The structure is not subject to any fabrication-related limitations because all the transmission lines used in the design have a characteristic impedance of 50 Ohms. The concept has been validated by designing a prototype matching network for N = 3 and extending it to N = 4, and N = 5 by adding elements to the branched stubs. All the structures are fabricated on ROGERS RO4003 substrate with a dielectric constant, er = 3.38 and height, h = 20 mils. The simulated and the measured results are in good accordance.

Targeting pulmonary vein myocardial sleeves with omnipolar mapping can reduce radiofrequency applications and procedure time: a proof-of-concept study.

There remains an imperative need to accurately map the left atrium in the setting of atrial fibrillation. While the pulmonary vein segmental ostial isolation plays a significant role in atrial fibrillation, clinical attempts to selectively ablate near the pulmonary vein myocardial sleeves have demonstrated a higher recurrence rate of arrhythmia given less precise mapping modalities. However, novel omnipolar mapping technology coupled with Advisor™ HD Grid Mapping Catheter may provide an advantageous profile to map and selectively ablate near the myocardial sleeves. This retrospective cohort underwent ablation targeting the pulmonary vein myocardial sleeves with the use of omnipolar mapping technology and later wide area circumferential ablation (WACA) was performed. The findings of this study demonstrated a few number of lesions were required to achieve all PVI targeting PVMS at 36 (95% CI 32-41) compared to WACA at 81 (95% CI 73-90). PVMS radiofrequency time was shorter at 314s (95% CI 278-350s) compared to 799s (95% CI 692-906s) for WACA. Mean procedure time to complete PVMS was 59min (95% CI 53-65) and to complete WACA was 90min (95% CI 80-100). Precision ablation near PVMS coupled with omnipolar technology may provide a superior profile in reducing procedure time and number of ablative lesions compared to WACA in the setting of atrial fibrillation with possible similar results. Future investigation using randomized controlled trials can help further support these findings.

Numerical investigation of diamond complementary logic integrated circuits

Silicon complementary metal oxide semiconductor (CMOS) technology drives the integrated circuit industry due to its energy efficiency. The narrow bandgap of silicon has led to the development of wide bandgap semiconductor materials, such as diamond, favored in power electronics, radiofrequency and extreme environment applications. Here we have established a model of the diamond CMOS logic inverter for the first time and successfully simulated the static and dynamic characteristics. The simulated physical model and relevant model parameters are well calibrated with experimental data of diamond p-FET in the literature. The simulation results demonstrate that the all-diamond CMOS inverters possess rail-to-rail operation and excellent inversion characteristics, with the peak gain of 83 V/V, the transition region of 0.25 V, and the noise margins for low and high level of 2.44 V and 2.26 V under VDD = 5 V. Particularly, all-diamond CMOS inverters have improved performance compared to the diamond-GaN inverters, operating at 500 °C with well-preserved inversion characteristics. This thermal reliability indicates that diamond CMOS inverters can be better monolithically integrated for applications in high-temperature environments in the future.

Fabrication of the Cu/AgCuTi/Nb composite for superconducting radio-frequency material under extreme service conditions based on electroplating additive manufacturing

The primary objective of this study is the development of Cu/Nb composite materials for Superconducting Radio-Frequency (SRF) applications under extreme service conditions characterized by a strong RF electromagnetic field, extremely low temperatures, and relatively low heat loss. A novel integrated manufacturing approach is proposed, which combines cold-sprayed AgCuTi alloy as an intermediate coating on the Nb surface and an electroplated Cu layer with a subsequent heat treatment brazing effect. This strategy aims to address the significant challenge of non-intermelting Cu and Nb while also considering effective lateral heat transfer. Mechanical property tests showed that the bond strength of Nb/AgCuTi/Cu composites exceeded 150 MPa. Low-temperature thermal transport tests indicate that the Residual Resistance Ratio (RRR) of the Cu layer surpasses 150, with a thermal conductivity at 4.2 K exceeding 1600 W/(m·K). Moreover, both the composite interface and mechanical properties of the specimens remain stable even after undergoing cyclic cold shock experiments. These findings suggest that the Nb/AgCuTi/Cu composite material developed in this study meets the technical requirements for long-term stable and high-performance operation in high-current and high-power superconducting accelerators.

Radio frequency regulates the multi‐scale structure and functional properties of starch from different genotypes of corn

SummaryThe purpose of this study was to investigate the multi‐scale structures, thermal, pasting, and textural properties of starch from different genotypes (dent and flint) of corn with varying moisture content (MC) (0.20, 0.25, and 0.30 kg kg−1 in dry basis) following radio frequency (RF) electromagnetic fields. As the MC increased, the amylose content in dent and flint corn starch rose from 14.60% to 19.70% and 14.80% to 24.63%, respectively, after the hot air (HA)‐RF treatment. With the increase in MC, the enhancement of starch–protein interaction and the change in starch molecule structure caused decreases in the crystallinity, short–range order structure, and enthalpy, while there were increases in the gelatinisation temperature, pasting viscosity, and textural properties of starch. The results showed that the RF treatment is an effective method for improving the processing performance of starch. Our data provide a foundation to expand the application of radio frequency in the food industry.