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ABSTRACT Background Case Presentation Intervention Results Conclusion Poly‐D,L‐lactic acid (PDLLA) is used for tear trough rejuvenation but can cause complications like nodular reactions. This report describes using a radiofrequency device to manage these nodules.A 42‐year‐old woman developed firm, non‐inflammatory nodules 3 weeks after receiving PDLLA (Juvelook) injections in the tear trough area. The nodules were firm and not associated with erythema or tenderness.The monopolar radiofrequency device was used directly on the nodules with 150 shots at an energy level 115 J, 28.75 J/cm². The treatment resulted in complete resolution of the nodules within 24 hours.The radiofrequency treatment effectively resolved the nodular reaction without recurrence, highlighting the device's compatibility with the unique structure of Juvelook's PDLLA.Radiofrequency therapy is effective for managing nodular reactions following PDLLA injections. Further research is needed to optimise protocols and improve the safety of biostimulator treatments in cosmetic procedures. [ABSTRACT FROM AUTHOR]

Background Aim Methods Conclusions Lasers and other energy‐based devices are increasingly becoming popular in aesthetic practice. Many centers employ doctors or technicians to perform these procedures where treating doctor and operating doctor may be different. Hence the need for standard operative protocols, to be followed while performing these procedures to avoid mistakes, complications and to get optimum results. In the current review article, group of doctors who have worked with these energy‐based devices over many years worked together and suggested the protocols to be followed for the most commonly used energy‐based procedures.To provide Standard operating protocols for the operator and staff to ensure, efficacy, safety, for the patient and for the devices.The following protocols have been drafted based on the best practices followed by the authors in their clinics and reflect their consensus opinion. The objective is to provide operating protocols in a standard format, which can be of use by practicing dermatologists and their staff. The protocols include both general guidelines for the laser room and specific protocols for different machines. The draft follows the following schema: General instructions for all the energy‐based devices. Specific protocols for different devices: Laser hair removal, fractional lasers, Q‐switched lasers, fractional microneedling radiofrequency and cryolipolysis. The protocols proposed help to maintain the uniformity and avoid complications. However, these instructions are generalized and not machine or lesion specific. There may be variations in the protocols depending on the treatment lesion and treating doctor as well as machine. [ABSTRACT FROM AUTHOR]

Integrated sensing and communications (ISAC) based on radio frequency (RF), merging the sensing and communication functionalities into a single platform, can effectively address the increasing demand for spectrums due to the proliferation of wireless devices. However, the ISAC commonly suffers from spectrum scarcity, high power consumption, and limited sensing capabilities. Here flexible self‐powered optical ISAC (O‐ISAC) is proposed and fabricated by preparing a high‐speed near‐infrared organic photodetector (NIR OPD) that exhibits a broad photodetection ranging from 300 to 1100 nm, specific detectivity over 1013 Jones, and −3 dB cutoff frequency over 1 MHz (λ = 1050 nm) in self‐powered mode, ranking as the fastest among self‐powered NIR OPDs in the region above 1000 nm. The device is fabricated by incorporating a narrow‐bandgap non‐fullerene acceptor BTPSV‐4Cl into the PCE‐10:BTPSV‐4F system to finely tune the film morphology and reduce trap states and energetic disorder. The semitransparent and regular NIR OPDs are integrated on one substrate to fabricate flexible O‐ISAC, realizing simultaneous accurate vital signs monitoring and high‐speed data transmission under ambient, sunlight, and NIR lighting conditions. It is envisioned that the proposed O‐ISAC will inspire a new generation of wireless technology to address RF limitations for emerging applications, such as intelligent healthcare, autonomous vehicles, and security. [ABSTRACT FROM AUTHOR]

Summary: The 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. [ABSTRACT FROM AUTHOR]

Summary: Freezing is a widely used method for preserving fresh strawberries, and selecting appropriate thawing technologies is crucial for obtaining high‐quality thawed strawberries. Radio frequency technology provides a promising method owing to its expeditious uniform heating mode with substantial penetration depth. This study investigated the effects of radio frequency thawing (RFT) using electrode gaps of 12, 14, or 16 cm on the quality attributes of frozen strawberries, comparing them with refrigerator thawing (RT) and microwave thawing (MWT). The results illustrated that strawberries thawed by RFT exhibited significantly lower firmness loss and higher levels of anthocyanins and ascorbic acid compared to RT and MWT methods. Specifically, strawberries thawed with a 12‐cm electrode gap under RFT showed faster thawing rates, increased phenolic content, and enhanced antioxidant activity. Overall, radio frequency technology shows great potential in enhancing the quality of thawed strawberries. [ABSTRACT FROM AUTHOR]

Objective: To assess the effectiveness and safety of treating erythematotelangiectatic rosacea using fractional radiofrequency (FRF). Methods: Twenty patients with a confirmed diagnosis of erythema capillaris rosacea were selected, and one side of each patient's face was randomly assigned to receive FRF treatments for three to six times, with an interval of 2 weeks between each treatment. VISIA, dermoscopy, and the Clinician's Erythema Evaluation Scale (CEA) were applied to evaluate the efficacy of the treatment before and after the treatment, to record the VAS scores and adverse reactions, and to conduct a patient satisfaction survey. Results: The characteristic counts and scores of red zone and porphyrin as assessed by VISIA test were significantly decreased, and the difference between the treated side and the pretreatment side was statistically significant (p < 0.05), and the efficacy of the treatment was statistically insignificant compared with the control side, except for the red zone and porphyrin which were statistically significant before and after the treatment (p > 0.05). By CEA score, the difference between the treated side after treatment and the control side was statistically significant (p < 0.05), and the difference between the treated side before and after treatment was statistically significant (p < 0.05); the difference between the control side before and after treatment was not statistically significant (p > 0.05). Dermatoscopic observation showed reduction in pore size, reduction of yellowish‐white and black horn plugs within the pores, lightening of the red background and thinning and blurring of the capillary structure on the treated side of the skin compared to the control side, and the skin on the treated side showed the above mentioned changes before and after the treatment as well. The mean pain score of the subjects was obtained by VAS score 3.67 ± 0.90. Adverse effects included mild edema, erythema, and microscopic crusting; no long‐term adverse effects were seen in all patients. The efficacy of FRF treatment was evaluated 1 month after the final treatment, and 85% of the subjects rated it as satisfactory, very satisfactory, and very satisfactory. Conclusion: FRF for the treatment of erythematous capillary dilatation rosacea is effective, safe, and suitable for clinical promotion. [ABSTRACT FROM AUTHOR]

Developing anode materials with high specific capacity and cycling stability is vital for improving thin‐film lithium‐ion batteries. Thin‐film zinc oxide (ZnO) holds promise due to its high specific capacity, but it suffers from volume changes and structural stress during cycling, leading to poor battery performance. In this research, we ingeniously combined polytetrafluoroethylene (PTFE) with ZnO using a radio frequency (RF) magnetron co‐sputtering method, ensuring a strong bond in the thin‐film composite electrode. PTFE effectively reduced stress on the active material and mitigated volume change effects during Li+ ion intercalation and deintercalation. The composite thin films are thoroughly characterized using advanced techniques such as X‐ray diffraction, scanning electron microscopy, and X‐ray photoelectron spectroscopy for investigating correlations between material properties and electrochemical behaviors. Notably, the ZnO/PTFE thin‐film electrode demonstrated an impressive specific capacity of 1305 mAh g−1 (=7116 mAh cm−3) at a 0.5C rate and a remarkable capacity retention of 82% from the 1st to the 100th cycle, surpassing the bare ZnO thin film (50%). This study provides valuable insights into using binders to stabilize active materials in thin‐film batteries, enhancing battery performance. [ABSTRACT FROM AUTHOR]

The unprecedented exposure of radiofrequency electromagnetic field (RF‐EMF) to humans from mobile communications raises serious public concern about the possibility of unexpected adverse health effects and has stimulated authorities to adopt precautionary exposure limits. These limits are distinctly different across countries, and the causes of these differences are unclear from the literature. This article is the first empirical analysis on the determinants of RF‐EMF exposure legislation, using a novel cross‐sectional database of 164 countries worldwide. The analysis shows that decentralization and mobile competition in countries with low mobile network deployment tend to promote more stringent RF‐EMF exposure limits across the dataset with 164 countries. In more decentralized countries, the regions had a greater influence on national legislation and could accommodate local demands with the advent of mobile technology in the 2000s. In contrast, decentralization and mobile competition in countries with high levels of mobile network deployment tend to relax RF‐EMF exposure limits in the sample of 61 countries with fifth‐generation (5G) technology. Indeed, restrictive RF‐EMF exposure limits are constraining 5G deployment in a context of the widespread adoption of mobile‐broadband technologies. These results should be useful for policymakers and mobile operators alike to anticipate the outcome of legislation in countries that have yet to introduce 5G technology. The results should also be useful when reviewing policies and strategies for the implementation of the upcoming 6G technology in frequency bands that will be increasingly higher (above 6 GHz up to THz for very local usage), and hence where the health effects on humans are less well studied. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusion Due to its unique features, pulsed field ablation (PFA) could potentially overcome some limitations of current radiofrequency (RF) ventricular tachycardia (VT) ablation. However, data on the use of PFA in this setting are currently scarce.Two patients with ischemic cardiomyopathy and previously failed RF VT ablations were treated with PFA.A total of 18 bipolar applications (case1) and seven bipolar applications (case2) were delivered to the infero‐lateral and infero‐septal areas (case1) and to the apical lateral left ventricular (LV) wall (case2), placing the catheter adjacent to the LV wall in the flower configuration. A rapid cessation of VT and restoration of sinus rhythm were observed during PFA delivery in both cases. Further applications were delivered to achieve complete elimination of late potentials. In case 1, during the in‐hospital stay, ECG monitoring did not show VT recurrences. Six‐month follow‐up was uneventful, with no VT recurrences at ICD interrogation. In case 2, due to postdischarge VT recurrences, a second RF procedure was scheduled 1 month later. The voltage map performed in sinus rhythm showed a low‐voltage zone located at the anterolateral wall, near the previous ablation site. Numerous late potentials were recorded. At the 6‐month follow‐up, no further VT recurrences were documented after RF redo ablation.While the speed of application and potential transmural effect can facilitate the ablation of large diseased endocardial areas, early loss of contact due to difficult pentaspline catheter manipulation in the LV could lead to insufficient contact force and, consequently, inadequate energy penetration. [ABSTRACT FROM AUTHOR]

Background Methods Results Conclusions 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. [ABSTRACT FROM AUTHOR]

Highlights Epsilon‐negative materials (ENM) at radio frequency, usually designed based on percolation theory, recently drew much attention because of their potential applications in capacitors, transistors, and antennas. However, randomly distributed conductive functional materials cannot achieve directional long‐range electron transportation within the material, resulting in decreased utilization efficiency. The morphology design of the substrate material can change the distribution state and electron transfer pathway of conductive fillers. By controlling the size of the polystyrene (PS) and the content of multi‐walled carbon nanotubes (MWCNTs), PS/MWCNTs composites with random structures and segregated structures were designed, both of which exhibited negative permittivity with increasing MWCNTs content. Further investigation revealed that negative permittivity behavior is due to the establishment of the conductive network and the plasma oscillation of free electrons. Moreover, components with segregated structures have lower percolation thresholds, as directional electron transport is achieved and conductive fillers are efficiently utilized. This work provides a new method for guiding the electron transport pathway and effectively changing the distribution state of conductive fillers in ENM. Negative permittivity is achieved by plasma oscillation at radio frequency. The segregated structure leads to a decrease in the percolation threshold. Epsilon‐negative materials have good prospects in inductive components. [ABSTRACT FROM AUTHOR]

Herein, radio frequency (RF) Joule heating is used to trigger dynamic covalent bond exchange in a furan‐maleimide Diels–Alder polymer (DAP). Prior work shows that carbon susceptors can be incorporated into materials and undergo Joule heating when exposed to an electric field. Herein, carbon nanotubes (CNTs) are added to the DAP to make the material responsive to RF fields, and to enable selective, noncontact healing behavior of DAP after electric field exposure. After healing, mechanical testing is conducted to compare the tensile strength and toughness of the healed samples with the mechanical properties of the original, undamaged samples. A 96.2% recovery in tensile strength and an 83.2% recovery in toughness are observed. Also, RF heating of DAP/CNT enables repeated bonding and debonding of the material, allowing for adhesion and deadhesion on demand. [ABSTRACT FROM AUTHOR]

Background Methods Results Conclusions When using lesion size index (LSI) to guide catheter ablation, it is unclear what combination of power, contact force and time would be preferable to use and what LSI target value to aim for. This study aimed at identifying desirable ablation settings and LSI targets by using tissue impedance drop as indicator of lesion formation.Consecutive patients, undergoing their first left atrial (LA) catheter ablation for atrial fibrillation, with radiofrequency energy (RF) powers of 20, 30 and 40 W were enrolled. Tissue impedance, contact force (CF), Force Time Integral (FTI) and LSI values were continuously recorded during ablation and sampled at 100 Hz. Mean CF and Contact Force Variability (CFV) were calculated for every lesion. The effect of RF power, ablation time, CF and CFV on impedance drop and LSI were assessed.A total of 3258 lesions were included in the analysis. For any target LSI value, use of higher RF powers translated into progressively higher impedance drops. The impact of lower CF and higher CFV on impedance drop was more relevant when using lower powers. Target LSI values corresponding to maximum impedance drop were identified depending on RF power, mean CF and CFV used.Even in the context of an LSI‐guided ablation strategy, use of lower or higher powers might lead to different lesion sizes. Different LSI targets might be needed depending on the combination of RF power, CF and CFV used for ablation. Incorporating indicators of catheter stability, like CFV, in the LSI formula could improve the predictive value of LSI for lesion size. Studies with clinical outcomes are required to confirm the clinical relevance of these findings. [ABSTRACT FROM AUTHOR]

Summary: An off‐chip compensation technology for low‐loss and broadband characteristics of radio frequency (RF) switches is proposed based on mathematical analysis of series shunt single pole double throws switches in this letter. This compensation technology can absorb the parasitic parameters of the switch Field Effect Transistor, improving the insertion loss and return loss of the switch as well as supporting higher bandwidth. To verify the design principle, a RF switch, using the SANAN GaAs 0.15 um pseudomorphic High Electron Mobility Transistors (pHEMT) process, and an off‐chip compensation network were designed and implemented. Specifically, after using an off‐chip compensation network, the measured bandwidth of switch has been expanded from 1.1–8.8 to 0.8–11 GHz, while the input and output return loss have also improved significantly. [ABSTRACT FROM AUTHOR]

Objective: Radiofrequency thermocoagulation (RFTC) has emerged as an effective and safe treatment method for patients with refractory focal epilepsy, when stereo‐electroencephalography (SEEG) is implanted. Although real‐world research results are still limited, a considerable number of patients have shown favorable outcomes with this less invasive method. This study aims to describe the outcomes and predictive factors of SEEG‐RFTC in real‐world research. Methods: A retrospective observational study was conducted on patients in the authors' epilepsy center. In total, 121 patients who underwent RFTC were included in the study. Post‐RFTC outcomes were evaluated using the seizure‐free rate and response rate (seizure frequency reduction more than 50%). Predictive factors influencing post‐RFTC outcome were considered by comparing different variables. Results: The mean follow‐up period was 18.3 months. Eighty‐two patients (67.8%) were responders and 54 (44.6%) were seizure free. In 36 patients with malformation of cortical development, the seizure‐free rate and the response rate were 69.44% and 83.33%, respectively. In 20 patients with hippocampal sclerosis, 19 patients were responders and 14 (70%) patients were seizure free at the last follow‐up. The MRI feature and etiology of epilepsy are correlated with the outcome. MR‐positive is a predictive factor for seizure freedom (p < 0.01) and responders (p < 0.01). Other factors have no predictive value for post‐RFTC outcome. Interpretation: SEEG‐RFTC is a safe procedure and yields favorable outcomes in numerous cases of focal DRE. The MRI feature and etiology of epilepsy are correlated with the seizure‐free rate and response rate. And MRI positivity is the predictor for good RFTC outcome. [ABSTRACT FROM AUTHOR]

The paper consists of a preliminary design and analysis of a lightweight composite backing structure for a side deployable solid mesh reflector intended for telecom application in the Ka‐Band. As the entire antenna reflector must withstand the forces related to the launching loads, the focus is addressed to the stiffness of the composite backing structure, so that the reflective metallic mesh will not be affected during launching phase, thus with no influence over the possible deformation of the mesh and on its radio frequency performance. It is shown that the proposed concept withstands the imposed launching requirements with a compromise on mass properties. [ABSTRACT FROM AUTHOR]

A magnetized capacitively coupled oxygen plasma was studied synergistically using phase resolved optical emission spectroscopy and particle‐based kinetic simulation. Discharge mode transitions from ambipolar mode into drift mode and finally into α mode induced by increasing the magnetic field were observed at different driving frequencies and different electrode gaps. The simulation results demonstrate that the discharge operating in the same mode exhibits a similar degree of electronegativity. By increasing driving frequency or electrode gap, the same discharge mode transition tends to occur at a lower magnetic field, and, meanwhile, the high electric field and electron power absorption shift from the bulk region to the sheath edge. [ABSTRACT FROM AUTHOR]

Objective: This retrospective study aims to compare the efficacy rates in treating hypertrophic scars among four distinct groups of patients who either underwent fractional Erbium: yttrium‐aluminum‐garnet (Er:YAG) laser or microplasma radiofrequency technology as standalone treatments or in combination with compound betamethasone transdermal administration. Method: The study retrospectively examined 208 patients treated at our institution from April 2011 to December 2022 for hypertrophic scars, receiving no less than three treatments (with an interval of 8 weeks between each). The patients were categorized into four groups: the F group (treated with fractional Er:YAG laser), the F + B group (treated with fractional Er:YAG laser combined with compound betamethasone transdermal administration), the P group (treated with microplasma radiofrequency technology), and the P + B group (treated with microplasma radiofrequency technology combined with compound betamethasone transdermal administration). The therapeutic effects were evaluated based on the changes in the Vancouver Scar Scale (VSS) scores before and after treatment in these groups. Results: There was no statistically significant difference in the VSS scores among the four groups before treatment. After undergoing three sessions of the aforementioned four types of treatment, all groups showed a decrease in VSS scores, with average posttreatment VSS scores for the F group scored 5.15 ± 2.084, F + B group scored 3.7 ± 1.781, P group scored 4.41 ± 1.933, and P + B group scored 3.16 ± 1.775, respectively. With an increasing number of treatments, the total effective rate gradually increased in all four groups, and the combination treatment using compound betamethasone transdermal administration proved more effective than the standalone treatment. Conclusion: All four treatments yielded favorable outcomes, with the combined therapy involving compound betamethasone transdermal administration proving more effective than the standalone treatments, meriting further clinical attention. [ABSTRACT FROM AUTHOR]

Background: With the rise in interest and demand for body contouring, beauty devices have continuously developed. Suction can aid in increasing the rate of fat breakdown by inducing a massage‐like effect, thereby increasing blood flow. Moreover, radiofrequency (RF) can boost fibroblast activity and help reduce cellulite. In addition, electrical muscle stimulation (EMS) can use electrical stimulation to induce muscle contraction, leading to an athletic, and skin elasticity‐increasing effect. Aims: This study aimed to assess the effects of body contouring, such as cellulite and swelling, in healthy Korean women to objectively prove the efficacy of an at‐home beauty device equipped with suction, RF, and EMS functions. Methods: For 8 weeks, 21 participants used the at‐home beauty device 3 days a week on their abdomen, thighs, and left calf. Validity assessments and subjective surveys were conducted at 4 and 8 weeks, including the first visit. Results: The results of the validity assessments revealed that cellulite, swelling, elasticity, femoral skin texture, and dermal density were significantly (p < 0.05) improved in the experimental group compared with those at the baseline. Conclusions: The results of this study demonstrate that the combination of suction, RF, and EMS function is effective for body skin, fat, and body shape management. For better body‐contouring effects, combining the beauty device with regular exercise and healthy eating habits is recommended. [ABSTRACT FROM AUTHOR]

In this study, a planar printed circuit board (PCB) coil with FR4 substrate was designed and simulated using the finite element method, and the results were analyzed in the frequency domain. This coil can be used in wireless power transfer (WPT) as a transmitter or receiver, eliminating wires. It can also be used as the receiver in radio frequency energy‐harvesting (RF‐EH) systems by optimizing the planar PCB coil to convert radio‐wave energy into electricity, and it can be employed as an excitation (transmitter) or receiver coil in nuclear magnetic resonance (NMR) spectroscopy. This PCB coil can replace the conventional coil, yielding a reduced occupied volume, a fine‐tuned design, reduced weight, and increased efficiency. Based on the calculated gain, power, and electromagnetic and electric field results, this planar PCB coil can be implemented in WPT, NMR spectroscopy, and RF‐EH devices with minor changes. In applications such as NMR spectroscopy, it can be used as a transceiver planar PCB coil. In this design, at frequencies of 915 MHz and 40 MHz with 5 mm between coils, we received powers of 287.3 μW and 480 μW, respectively, which are suitable for an NMR coil or RF‐EH system. [ABSTRACT FROM AUTHOR]

We propose a 10‐GHz 2 × 2 phased‐array radio frequency (RF) receiver with an 8‐bit linear phase and 15‐dB gain control range using 65‐nm complementary metal–oxide–semiconductor technology. An 8 × 8 phased‐array receiver module is implemented using 16 2 × 2 RF phased‐array integrated circuits. The receiver chip has four single‐to‐differential low‐noise amplifier and gain‐controlled phase‐shifter (GCPS) channels, four channel combiners, and a 50‐Ω driver. Using a novel complementary bias technique in a phase‐shifting core circuit and an equivalent resistance‐controlled resistor–inductor–capacitor load, the GCPS based on vector–sum structure increases the phase resolution with weighting‐factor controllability, enabling the vector–sum phase‐shifting circuit to require a low current and small area due to its small 1.2‐V supply. The 2 × 2 phased‐array RF receiver chip has a power gain of 21 dB per channel and a 5.7‐dB maximum single‐channel noise‐figure gain. The chip shows 8‐bit phase states with a 2.39° root mean‐square (RMS) phase error and a 0.4‐dB RMS gain error with a 15‐dB gain control range for a 2.5° RMS phase error over the 10 to10.5‐GHz band. [ABSTRACT FROM AUTHOR]

The decoupled 8 × 2 transceiver array has been shown to achieve a mean B1+ of 11.7 uT with a coefficient of variation of ~11% over the intracranial brain volume for 7‐T MR imaging. However, this array may be thought to give lower signal‐to‐noise ratio (SNR) and higher g‐factors for parallel imaging compared with a radio frequency (RF) receive‐only coil due to the latter's higher coil count and use of coil overlap to reduce the mutual impedance. Nonetheless, because the transceiver's highly decoupled design (pertinent for transmission) should also be constructive for reception, we measured the noise correlation, g‐factors, and SNR for the decoupled transceiver in comparison with a commercial reference coil. We found that although the transceiver has half the number of receive elements in comparison with the reference coil (16 vs. 32), comparable g‐factors and SNR over the head were obtained. From five subjects, the transceiver versus reference coil SNR was 65 ± 10 versus 67 ± 15. The mean noise correlation for all coil pairs was 10% ± 5% and 12% ± 9% (transceiver and reference coil, respectively). As changes in load impedance may alter the S parameters, we also examined the performance of the transceiver with tuned and matched (TM) versus untuned and unmatched (UTM) conditions on five subjects. We found that the noise correlation and SNR are robust to load variation; a noise correlation of 10% ± 5% and 10% ± 6% was determined with TM versus UTM conditions (SNRUTM/SNRTM = 0.97 ± 0.08). Finally, we demonstrate the performance of the array in human brain using T2‐weighted turbo spin echo imaging, finding excellent SNR performance in both caudal and rostral brain regions. [ABSTRACT FROM AUTHOR]

Purpose: The drift in radiofrequency (RF) power amplifiers (RFPAs) is assessed and several contributing factors are investigated. Two approaches for prospective correction of drift are proposed and their effectiveness is evaluated. Methods: RFPA drift assessment encompasses both intra‐pulse and inter‐pulse drift analyses. Scan protocols with varying flip angle (FA), RF length, and pulse repetition time (TR) are used to gauge the influence of these parameters on drift. Directional couplers (DICOs) monitor the forward waveforms of the RFPA outputs. DICOs data is stored for evaluation, allowing calculation of correction factors to adjust RFPAs' transmit voltage. Two correction methods, predictive and run‐time, are employed: predictive correction necessitates a calibration scan, while run‐time correction calculates factors during the ongoing scan. Results: RFPA drift is indeed influenced by the RF duty‐cycle, and in the cases examined with a maximum duty‐cycle of 66%, the potential drift is approximately 41% or 15%, depending on the specific RFPA revision. Notably, in low transmit voltage scenarios, FA has minimal impact on RFPA drift. The application of predictive and run‐time drift correction techniques effectively reduces the average drift from 10.0% to less than 1%, resulting in enhanced MR signal stability. Conclusion: Utilizing DICO recordings and implementing a feedback mechanism enable the prospective correction of RFPA drift. Having a calibration scan, predictive correction can be utilized with fewer complexity; for enhanced performance, a run‐time approach can be employed. [ABSTRACT FROM AUTHOR]

Broadband analog signal processors utilizing silicon photonics have demonstrated a significant impact in numerous application spaces, offering unprecedented bandwidths, dynamic range, and tunability. In the past decade, microwave photonic techniques have been applied to neuromorphic processing, resulting in the development of novel photonic neural network architectures. Neuromorphic photonic systems can enable machine learning capabilities at extreme bandwidths and speeds. Herein, low‐quality factor microring resonators are implemented to demonstrate broadband optical weighting. In addition, silicon photonic neural network architectures are critically evaluated, simulated, and optimized from a radio‐frequency performance perspective. This analysis highlights the linear front‐end of the photonic neural network, the effects of linear and nonlinear loss within silicon waveguides, and the impact of electrical preamplification. [ABSTRACT FROM AUTHOR]

Reconfigurable metasurfaces have exhibited significant potential in wireless communication owing to their capacity to transmit information without relying on traditional complex radio frequency (RF) chain transmitters. Nonetheless, the majority of metasurface‐based wireless communication systems modulate signals only in the time domain. Here, an amplitude‐phase reconfigurable metasurface is proposed to establish a wireless communication system that can simultaneously transmit different messages to users by encoding digital signals within the spatial domain. By changing the bias voltages of varactors integrated in the meta‐atom, the reconfigurable metasurface can achieve independent 3‐bit phase and 1‐bit amplitude coding. Through a beamforming methodology, the proposed metasurface generates diverse scattering beams with suppressed sidelobe levels, which not only enables multiple channels through space coding but also reduces signal leakage in undesired directions. Numerical simulations and experiments are carried out to verify the beamforming scheme, and a dual‐channel wireless communication system is established. The results show that two distinct images can be simultaneously retrieved by two separate users, which demonstrates the dual‐channel transmission capability of the wireless communication system. The proposed strategy opens up an avenue for implementing multi‐channel wireless communication systems, which indicates its great potential in multiple‐user collaborative wireless communication and radar systems. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study is to determine the optimum and fine values of the number and transmission angles of tilted plane waves for coherent plane‐wave compounding (CPWC)‐based high local pulse wave velocity (LPWV) estimation. Methods: A Verasonics system incorporating a linear array probe L14‐5/38 with 128 elements and a pulsatile pump, CompuFlow1000, were used to acquire radio frequency data of 3, 5, 7, and 9 tilted plane wave sequences with angle intervals from 0° to 12° with a coarse interval increment step of 1°, and the angle intervals from 0° to 2° with a fine interval increment step of 0.25° from a carotid vessel phantom with the LPWV of 13.42 ± 0.90 m/s. The mean value, standard deviation, and coefficients of variation (CV) of the estimated LPWVs were calculated to quantitatively assess the performance of different configurations for CPWC‐based LPWV estimation. Ten healthy human subjects of two age groups were recruited to assess the in vivo feasibility of the optimum parameter values. Results: The CPWC technique with three plane waves (PRF of 12 kHz corresponding to a frame rate of 4000 Hz) with an interval of 0.75° had LPWVs of 13.52 ± 0.08 m/s with the lowest CV of 1.84% on the phantom, and 5.49 ± 1.46 m/s with the lowest CV of 12.35% on 10 subjects. Conclusions: The optimum parameters determined in this study show the best repeatability of the LPWV measurements with a vessel phantom and 10 healthy subjects, which support further studies on larger datasets for potential applications. Access the CME test here and search by article title. [ABSTRACT FROM AUTHOR]

This study reports coordinated observation of ionospheric irregularities from VHF Radar, GPS and IRNSS (Indian Regional Navigation Satellite System), from regions near the northern crest of the EIA (Equatorial Ionization Anomaly), which has not been explored earlier. Efforts have been made to study the signal‐in‐space environment for concurrent detection of ionospheric irregularities over a range of radio frequency, starting from 53 MHz of the Radar, to L‐band of GPS at 1,575.42 MHz and S band signal of IRNSS at 2,492.5 MHz. The radar is operational at Ionosphere Field Station, Haringhata (geographic latitude 22.93°N; geographic longitude 88.51°E; magnetic dip angle 36.2°N) of University of Calcutta. The GPS and IRNSS data are recorded at Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 36°N), separated from Haringhata by 50 km. The spatial as well as temporal variations of irregularities affecting different radio frequencies have been presented. Coordinated observations have been made during period of March–April 2023. Results of the study reveal the common zone of impact of the different radio frequency links spanning from 53 to 2,592.5 MHz and was identified within 16°–25°N, 85°–90°E. During coordinated observations made over several days, irregularity structures have been observed with radar, having backscatter SNR (Signal to Noise ratio) intensity within −5 to 15 dB. During this time, while intense L band scintillation was recorded on multiple satellites of GPS, scintillation recorded at S band signal was moderate to intense. Key Points: Coordinated observation of ionospheric irregularities from a low latitude station near the northern crest of equatorial ionization anomalyStudy of Signal‐in‐Space (SIS) environment over a range of radio signal from 53 to 2,592.5 MHzInvestigation of spatial confinement of ionospheric irregularities using radar and space based satellite signals at L band and S band [ABSTRACT FROM AUTHOR]

Summary: Underwater wireless sensor network (UWSN) connects the real world to the hidden resources available deep into the sea using sensor nodes deployed sparsely and are interconnected to gather information for any movement/change in the ocean. The computed information on nodes obtained from concurrently running UWSN's applications will be meaningful, only if the location of this change will be identified. Nevertheless, it is always difficult to obtain the exact location coordinates of any misadventure like tectonic plate's movement but using localization algorithms in UWSN helps to obtain the coordinates. Since localization algorithms for terrestrial networks are not feasible for UWSN because of environmental challenges. Moreover, GPS systems do not work after 15 m of depth and the radio frequency gets suppressed. So, the requirement arises to analyze existing localization approaches in the deep sea where acoustic signals are used for communication and data transfer. In this paper, along with describing the UWSN's applications and challenges, the underwater localization schemes are reviewed to present, summarize, and mention the scope of improvement. Further, classification into range‐based and range‐free categories of these schemes is depicted with implementation in the NS2.30 simulation environment of some of the recent techniques to showcase the reasons for better performance. [ABSTRACT FROM AUTHOR]

Summary: Within the domain of contemporary wireless communication systems, crafting Low‐Noise Amplifiers (LNA) holds a pivotal significance in achieving heightened signal sensitivity and comprehensive system efficacy and suppresses noise contributions from subsequent stages. Additionally, the low noise figure (NF) and high gain are critical LNA performance parameters in portable applications. Normally, LNA contains issues in noise performance, amplification, bandwidth, gain, and stability. To overcome these challenges, there must be a proper selection of transistors, harmonious impedance calibration, bias optimization, and circuit fine‐tuning. Moreover, metal oxide semiconductor field effect transistors (MOSFETs) are a popular choice in LNA design because of their excellent noise performance, high input impedance, complementary metal‐oxide semiconductor (CMOS) integration capabilities, low power operation, and suitability for a wide range of frequency applications. Through simulation and iterative enhancement, the LNA showcases remarkable Noise Figure, amplification, and linearity over a designated frequency span. This creation contributes to the advancement of radio frequency (RF) circuitry by designing an approach for LNA crafting that harmonizes conflicting prerequisites and unveils effective noise mitigation tactics. The outcomes emphasize the importance of a deliberated circuit architecture and parameter adjustment in accomplishing superlative LNA capabilities, rendering it fit for assimilation into diverse communication systems that demand minimal noise and heightened sensitivity. [ABSTRACT FROM AUTHOR]

In this paper, to analyze the tuning range (TR) of transistors, we introduced two streamlined modeling approaches that can precisely predict the extent and direction of the TR. The first approach, known as the average DC (Id) method, employed a simplified circuit model to dissect transistor characteristics, enabling us to understand the general trajectory of the TR. The second approach involved the transient current Id (tc) method, which offers a nuanced portrayal of the transistor's real‐world performance. By analyzing the current fluctuations within the transistor during transient states, its tuning capabilities could be more accurately ascertained. Further, this paper presents several designs for ultra‐wide‐tuning‐range complementary metal–oxide–semiconductor (CMOS) voltage‐controlled oscillators (VCOs) that employ a novel two‐mode current‐starved delay cell, featuring a tunable transistor‐based current source for coarse frequency adjustment operating in synergy with a varactor for precise tuning. Using the 65‐nm CMOS process, three prototype VCOs (Designs 2/3/4) based on the new cell and targeting different numbers of phases and performance were fabricated, thoroughly characterized, and compared with their traditional inverter‐based counterpart (Design 1). Design 1 featured an inverter‐based four‐phase structure, with an output frequency range of 3.14–9.82 GHz, i.e., a radio frequency (RF) TR of 103%, with phase noise (PN) ranging from 137.7 to 132.1 dBc/Hz at an offset of 100 MHz, figure of merit with tuning range and area (FoMTA) varying from 200.7 to 205.1 dBc/Hz, and area of 0.0036 mm2. In contrast, Designs 2/3/4, based on the new delay cell, featured 8/3/4 phases, with output frequencies in the ranges of 1.14–9.17, 1.26–16.53, and 1.15–18.32 GHz, respectively, resulting in increased RF TRs of 155.8%, 171.7% and 176.4%, as well as PN at an offset of 100 MHz in the ranges of 142.1–138, 130.5–131.3, and 131.9–129.6 dBc/Hz, respectively. This yielded better FoMTAs in the ranges of 201.2–209.9, 205.3–217.9, and 194.1–209.9 dBc/Hz, thus allowing the VCOs to maintain consistent performance across the frequency band and occupy comparable or smaller silicon areas of 0.00425, 0.000972, and 0.00348 mm2 in the same 65 nm technology. These designs showcase the versatility and efficiency of the two‐mode current‐starved delay architecture, which offers wide TRs, tiny areas, and competitive performance metrics for various applications in RF integrated circuits. [ABSTRACT FROM AUTHOR]

Background Aims Methods Results Conclusion Noninvasive monopolar radiofrequency (NMRF) is widely used for dermal and subdermal volumetric heating, yet detailed research on its effects on dermal temperature is scarce.This study evaluates the impact of NMRF on dermal temperature and its potential for dermal remodeling using a porcine model.Noninvasive monopolar radiofrequency was applied to porcine skin with temperature monitoring via optic fiber technology and forward‐looking infrared thermal imaging. Safety was evaluated using nitro blue tetrazolium chloride assessments, and effectiveness was determined through histological examinations before and after treatment.Noninvasive monopolar radiofrequency treatment in a porcine model achieved effective dermal remodeling with no thermal damage, recording peak temperatures of 50°C, 60°C, and 70°C. Histological analysis showed increased collagen density, indicating successful tissue remodeling.Noninvasive monopolar radiofrequency is effective in delivering controlled dermal heating and enhancing collagen synthesis, promoting safe and efficient skin tightening and dermal remodeling in a porcine model. It presents a viable option for skin rejuvenation therapies. [ABSTRACT FROM AUTHOR]

Background Purpose Methods Results Conclusions Maintaining an adequate temperature at the target site is essential for effective ablation. We hypothesized that a tissue temperature‐controlled (T‐Con) catheter for cavotricuspid isthmus (CTI) ablation could improve the procedural ablation parameters.To evaluate the efficacy and safety of the T‐Con (DiamondTemp™) catheter for CTI ablation compared with non‐irrigation (Non‐Irri) and irrigation (Irri) catheters.We analyzed 150 patients who underwent prophylactic CTI ablation combined with pulmonary vein isolation. The Non‐Irri, Irri, and T‐Con catheter groups comprised 50 patients each, and the ablation procedural parameters and complications were compared between these groups.There were no significant differences in clinical background characteristics among the three groups. The Kruskal–Wallis and post hoc tests demonstrated that the T‐Con group showed the lowest total radiofrequency energy delivery time among the three groups (median [25 and 75 percentiles]: 340 [209, 357], 147 [100, 199], and 83 [61, 109] s, respectively in the Non‐Irri, Irri, and T‐Con groups; T‐Con versus Non‐Irri, p < .01; T‐Con versus Irri, p < .01). The total procedural time and acute reconnection rate in the T‐Con group (264 s and 4%, respectively) were lower than those in the Non‐Irri group (438 s and 24%) but were similar to those in the Irri group (268 s and 6%). No significant complications were observed in any group.The T‐Con catheter achieved a short energy delivery time and a low acute reconnection rate, indicating its potential as an alternative catheter for CTI ablation. [ABSTRACT FROM AUTHOR]

Background Objective Methods Results Conclusion Growing demand for facial rejuvenation drives advancements in these therapies, including laser, radiofrequency, and focused ultrasound, alongside thermal stimulation adjuncts. These methods, known for stimulating collagen regeneration, skin tightening, and lifting, have gained popularity due to their minimal side effects, low trauma, and high safety, demonstrating favorable outcomes in clinical practice.We sought to assess the efficacy of ultrasound skin tightening for brow lift within the scope of a procedure addressing facial sagging across the entire face. Our aim was to explore a noninvasive method capable of effectively enhancing mild to moderate brow ptosis by tightening and lifting the skin in the upper facial region.This was a rater‐blinded, prospective cohort study. The upper facial region of the participants was treated with the new device, micro‐focused ultrasound (MFU), in model D3.0/D2.0/M3.0. Outcomes of brow lift were measured in comparison of pretreatment and posttreatment photographs and three‐dimensional (3D) vector analysis.A total of 42 participants (37 females) were enrolled, with 2 participants withdrawing from the trial, resulting in 40 subjects who completed 180‐day‐follow‐up and evaluation. 35 (87.5%) were deemed to have clinically significant brow elevation by two blinded assessors (experienced clinicians) at 180‐day posttreatment (p < 0.01). The mean change in brow height after 90‐day was 2.16 ± 0.63 mm at the frontal position (straight‐ahead gaze) (p < 0.01). The 3D vector analysis reveals varying magnitudes of vector displacement in the upward and outward directions of the skin on the frontal region above the eyebrows.Focused ultrasound appears to be a safe and effective method for upper facial skin rejuvenation. A single focused ultrasound treatment on the forehead and temple areas resulted in an average brow elevation of 2.1 mm. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is widely used in clinical care and medical research. The signal‐to‐noise ratio (SNR) in the measurement affects parameters that determine the diagnostic value of the image, such as the spatial resolution, contrast, and scan time. Surgically implanted radiofrequency coils can increase SNR of subsequent MRI studies of adjacent tissues. The resulting benefits in SNR are, however, balanced by significant risks associated with surgically removing these coils or with leaving them in place permanently. As an alternative, here the authors report classes of implantable inductor–capacitor circuits made entirely of bioresorbable organic and inorganic materials. Engineering choices for the designs of an inductor and a capacitor provide the ability to select the resonant frequency of the devices to meet MRI specifications (e.g., 200 MHz at 4.7 T MRI). Such devices enhance the SNR and improve the associated imaging capabilities. These simple, small bioelectronic systems function over clinically relevant time frames (up to 1 month) at physiological conditions and then disappear completely by natural mechanisms of bioresorption, thereby eliminating the need for surgical extraction. Imaging demonstrations in a nerve phantom and a human cadaver suggest that this technology has broad potential for post‐surgical monitoring/evaluation of recovery processes. [ABSTRACT FROM AUTHOR]

A graphene field‐effect transistor (GFET) based on chemical vapour deposited (CVD) Ge‐based graphene was reported and the low‐temperature electrical characteristics primarily investigated. The self‐alignment technique was used to fabricate a GFET to reduce parasitic effects and improve transconductance and cut‐off frequency. To further explore the electrical properties, the direct current and radio frequency characteristics of the GFET were studied over a temperature range from 4.2 to 300 K, considering the temperature‐dependent resistivity of intrinsic Ge. The direct current characteristic of the GFET for 110‐nm gate length, particularly the transconductance performance, exhibits a tiny variation of only ∼$\sim$5% across this temperature range. However, the cut‐off frequency experiences a considerable increase, improving several tens of times when the temperature decreases to 4.2 K, with a maximum value of 3.49 GHz. This work illustrates a meaningful advancement in applying GFETs in the low‐temperature, high‐frequency domain. [ABSTRACT FROM AUTHOR]

In this letter, a low‐cost and easy‐to‐embed 7‐bit 360° phase shifter with transitions is presented for applications to beamforming in the large‐scale phased array. In the proposed 360° phase shifter, the topology of the reflection‐type phase shifter (RTPS) is employed, composed of a 3‐dB branchline coupler terminated with two tunable parallel L–C loads. First, a two‐step phase extraction process for RTPS is applied to design the RTPS rapidly with competitive performance, including 360° phase range and low insertion loss. A huge amount of parameter sweep is reduced in the design and test. Meanwhile, the parameter of inductors in the tunable loads is investigated effectively, to achieve the minimal phase step. Second, aiming at the enhanced performance of beamforming and improved flexibility of integration, the stripline is adopted in the design of the phase shifter, avoiding the interference on antenna radiation effectively. To facilitate the integration with antenna and radio frequency connectors of the input and output signals, a stripline‐to‐microstrip line transition with electromagnetic bandgap structures is adopted. By this means, the complexity and cost of fabrication are decreased. Finally, fabricated in the low‐cost printed circuit board technology, our proof‐of‐concept design operated from 2.4 to 2.5 GHz is measured and achieves a 386.8° phase shift range with an insertion loss of 2.21 ± 0.82 dB at 2.45 GHz. [ABSTRACT FROM AUTHOR]

Background Objective Methods Results Conclusions Despite advances in efficacy and safety of pulmonary vein isolation (PVI), atrial fibrillation (AF) recurrence after PVI remains common. PV‐reconnection is the main finding during repeat PVI procedures performed to treat recurrent AF.To analyze pulmonary vein (PV) reconnection patterns during repeat ablation procedures in a large cohort of consecutive patients undergoing radio frequency or cryoballoon‐based PVI.Retrospective analysis of PV‐reconnection patterns and analysis of re‐ablation strategies in consecutive index RF‐ and CB‐based PVI and their respective re‐ablation procedures during concomitant usage of both energy sources at a single high‐volume center in Germany.A total of 610 first (06/2015–10/2022) and 133 s (01/2016–11/2022) repeat ablation procedures after 363 (60%) RF‐ and 247 (40%) CB‐based index PVIs between 01/2015 and 12/2021 were analyzed. PV‐reconnection was found in 509/610 (83%) patients at first and 74/133 (56%) patients at second repeat procedure. 465 of 968 (48%) initially via CB isolated PVs were reconnected at first re‐ablation but 796 of 1422 initially RF‐isolated PV (56%) were reconnected (OR: 0.73 [95% CI: 0.62–0.86]; p < .001). This was driven by fewer reconnections of the left PVs (LSPV: OR: 0.60 [95% CI: 0.42–0.86]; p = .005 and LSPV: 0.67 [0.47–0.95]; p = .026). PV‐reconnection was more likely after longer, RF‐based index PVI and in older females. Repeat procedures were shorter after CB‐compared to after RF‐PVI.Reconnection remains the most common reason for repeat AF ablation procedures after PVI. Our data suggest to preferentially use of the cryoballoon during index PVI, especially in older women. [ABSTRACT FROM AUTHOR]

The compact model plays a pivotal role as a critical link between device fabrication and circuit design. While conventional compact model theories and techniques are generally mature, the intricate physical mechanisms of gallium nitride (GaN) high‐electron mobility transistors (HEMTs) pose challenges due to their strong non‐linearity in high‐power radio frequency (RF) applications. This complexity hinders achieving the required precision for applications using traditional modeling methods. Therefore, the development of physics‐based compact modeling techniques becomes crucial for a deeper understanding of the intricate features of GaN HEMTs. This paper explores the advancements and the current state‐of‐the‐art in physics‐based compact models. The comprehensive review covers both intrinsic core models and real‐device effects models. Core models are presented with a focus on fundamental concepts, development overviews, and applications. Additionally, the real‐device effects models are introduced, encompassing advanced characterization techniques and modeling methodologies. Furthermore, the paper outlines future trends in physics‐based compact modeling, providing valuable insights for individuals engaged in transistor compact modeling work. [ABSTRACT FROM AUTHOR]

Summary: This study presents a compact hybrid dual‐frequency impedance transformer that is suitable for sources and loads having frequency‐dependent complex impedances. The basic transformer comprises two transmission lines and two shunt stubs, and this configuration is adequate for the design of a dual‐frequency impedance transformer for a few sources and loads. Compared with other studies, this work presents a distinct derivation concept to obtain the circuit parameters, thus enabling the achievement of a compact circuit. For some particular sources and loads that the basic structure is difficult to match because of line width limitations, lumped elements are added to overcome the limitation and further reduce the circuit size. The derived design formulas avoid errors caused by frequency‐dependent deviations in the component values due to parasitic effects, which constitute a critical problem in Radio Frequency (RF) circuits that employ lumped elements. The simulated results are in good agreement with the measured results, and the frequency responses obtained herein validate the proposed structure and design procedure. [ABSTRACT FROM AUTHOR]

Stereoelectroencephalography‐guided radiofrequency thermocoagulation (SEEG‐guided RF‐TC) is a treatment option for focal drug‐resistant epilepsy. In previous studies, this technique has shown seizure reduction by ≥50% in 50% of patients at 1 year. However, the relationship between the location of the ablation within the epileptogenic network and clinical outcomes remains poorly understood. Seizure outcomes were analyzed for patients who underwent SEEG‐guided RF‐TC and across subgroups depending on the location of the ablation within the epileptogenic network, defined as SEEG sites involved in seizure generation and spread. Eighteen patients who had SEEG‐guided RF‐TC were included. SEEG‐guided seizure‐onset zone ablation (SEEG‐guided SOZA) was performed in 12 patients, and SEEG‐guided partial seizure‐onset zone ablation (SEEG‐guided P‐SOZA) in 6 patients. The early spread was ablated in three SEEG‐guided SOZA patients. Five patients had ablation of a lesion. The seizure freedom rate in the cohort ranged between 22% and 50%, and the responder rate between 67% and 85%. SEEG‐guided SOZA demonstrated superior results for both outcomes compared to SEEG‐guided P‐SOZA at 6 months (seizure freedom p =.294, responder rate p =.014). Adding the early spread ablation to SEEG‐guided SOZA did not increase seizure freedom rates but exhibited comparable effectiveness regarding responder rates, indicating a potential network disruption. [ABSTRACT FROM AUTHOR]

Emerging millimeter‐wave wireless communication systems require high‐performance radio frequency switches to support advanced functionality such as frequency agility, circuit reconfigurability, and beamforming. Ferroelectric (FE)‐gated AlGaN/GaN high‐electron‐mobility transistors (HEMTs) (FeHEMTs) are developed and demonstrated as a technology option for this important role. AlGaN/GaN HEMT heterostructures grown by metal‐organic chemical vapor deposition are augmented with a FE gate stack comprising atomic layer deposition‐grown HfZrO2. In addition, highly doped regrown source and drain Ohmic contacts are integrated into an improved fabrication process flow. This improved process leads to contact resistances of 0.105 Ω mm and a reduction in switch on‐resistance as compared to prior reports, as well as drain current densities of 1 A mm−1 and measured ft = 54 GHz for gate lengths of 0.1 μm. The improved contact and gate length scaling makes FeHEMTs a promising candidate for mm‐wave switch applications achieving a reported switch figure of merit of fCO = 1.55 THz. [ABSTRACT FROM AUTHOR]

Next‐generation "Beyond 5G (B5G)/6G" wireless network systems have been researched and developed for meeting the rapid growth of mobile traffic. A high‐yield fabrication process of InP‐based transistors and tera‐hertz monolithic integrated circuits with 300 GHz operation is reported, which is a candidate frequency for "Beyond 5G/6G" network systems. The main focus is on a high‐yield and reproductive fabrication process of InP‐based high electron mobility transistors (HEMTs) while revisiting previous studies. The DC and radio frequency characteristics of fabricated InP‐HEMTs from the viewpoint of integrating circuits are described. Then, high‐frequency performances of ft = 280 GHz and fmax = 860 GHz in the bias conditions of Vgs/Vds = 0.2/1.1 V with good uniformity are obtained. Finally, InP‐based 300 GHz‐band mixer and power amplifiers are introduced, to which a backside process is also applied for ensuring their stability and enhancing output power. [ABSTRACT FROM AUTHOR]

Background: Microplasma fractional radiofrequency (MP FRF) technology has been increasingly used for acne scars. Nevertheless, little evidence has analyzed the factors influencing its effectiveness before and during treatment. Aims: To evaluate the clinical factors affecting the effectiveness of MP FRF therapy for atrophic acne scars. Methods: We analyzed retrospectively the clinical data of 79 acne scar patients treated with MP FRF technology. The outcome of interest included the effectiveness and adverse events after MP FRF treatment. Multivariable logistic regression was utilized to evaluate clinical factors associated with effectiveness after the initial session. Results: All patients received 115 sessions of MP FRF therapy (average: 1.5 sessions). Twenty‐eight (35.4%) patients improved moderately to excellently after one session. We found that the severe grade before treatment was negatively correlated with the effectiveness according to Goodman–Baron qualitative scores (OR = 0.02, 95% CI [0.001, 0.37], p = 0.009). The presence of icepick scars was also a negative correlation factor for the effectiveness (OR = 0.06, 95% CI [0.004, 1.00], p = 0.049). Furthermore, after excluding the effects of icepick scars and Goodman–Baron scores before treatment, ECCA scores were also correlated with effectiveness (OR = 1.04, 95% CI [1.01, 1.06], p = 0.009). Conclusion: MP FRF therapy was effective in treating atrophic acne scars with no permanent adverse events. The severity of Goodman–Baron qualitative scores and icepick scars were independent clinical factors affecting effectiveness, suggesting the possible requirement for additional treatments other than MP FRF for severe acne scars and icepick scars. [ABSTRACT FROM AUTHOR]

Objective: To investigate the histological properties of microplasma radiofrequency (MPRF) using a stationary tip in different treatment strategies on porcine skin. Methods: Two Bama miniature pigs received MPRF treatment with two types of stationary tips in eight groups of parameters (power, duration, and pass) on dorsal skin. Skin samples were collected from each treatment zone immediately, at 1 week and 1, 3, and 6 months after treatment. Hematoxylin and eosin (HE) and Masson staining were performed to assess histologic changes as well as neocollagenesis. The dynamic changes of heat shock protein 47 (HSP47) and heat shock protein 72 (HSP72) were also detected by immunohistochemistry. Results: Skin damage increased with pulse energy, duration, and pass. Longer durations or repeated treatments may cause particularly severe skin damage. During the wound healing process, the newborn collagen of the dermis is rearranged. The distribution of HSP47 and HSP72 was consistent with the extent of collagen remodeling. It peaked 1 month after treatment. Conclusion: MPRF can effectively cause epidermal ablation, dermal collagen hyperplasia, and remodeling. Increasing power should be the first choice when increasing treatment intensity. For longer durations or repeated treatments, caution should be taken to avoid excessive skin trauma. [ABSTRACT FROM AUTHOR]

Purpose: To utilize the transmit radiofrequency (RF) field in MRI as a power source, near or within the field of view but without affecting image quality or safety. Methods: Power harvesting is performed by RF induction in a resonant coil. Resulting RF field distortion in the subject is canceled by a selective shield that couples to the harvester while being transparent to the RF transmitter. Such shielding is designed with the help of electromagnetic simulation. A shielded harvester of 3 cm diameter is implemented, assessed on the bench, and tested in a 3T MRI system, recording power yield during typical scans. Results: The concept of selective shielding is confirmed by simulation. Bench tests show effective power harvesting in the presence of the shield. In the MRI system, it is confirmed that selective shielding virtually eliminates RF perturbation. In scans with the harvester immediately adjacent to a phantom, up to 100 mW of average power are harvested without affecting image quality. Conclusion: Selective shielding enables stealthy RF harvesting which can be used to supply wireless power to on‐body devices during MRI. [ABSTRACT FROM AUTHOR]

The urban radio‐frequency (RF) noise generated by our cities continues to change with time. Although models exist to describe the RF noise as functions of frequency and urban land use types, very few models describe the spatial character or structure of the noise on the scales of city blocks (50–150 m). The goal of this work is to investigate the connection between urban morphology and the higher‐order spatial statistics of the noise field. To achieve this goal, a large measurement campaign was conducted in Boston, Massachusetts. Many spatial measurements allowed for calculation of spatial correlation functions of noise power in three different neighborhoods, which were used to quantify the spatial structure of the fields. A statistical point source model is then developed, with adjustable parameters relating to urban morphology. Good agreement between the model and the experimental correlation functions suggests the 25 MHz urban noise field is well described by a random network of fixed point sources, radiating with a 1/r power law behavior. Plain Language Summary: Our modern cities are filled with electronic devices. Each device can emit radiation and contribute to what is called the urban radio‐frequency noise field. The noise field is the combined effect from all these devices. If the noise field is strong enough it can negatively impact wireless communication, and the use of other electric devices. It is important to better understand the nature of the noise field in order to mitigate and plan for its negative effects. This paper describes in detail how the noise field is distributed in space, or its spatial structure. A theoretical model or tool is developed to help predict how the noise field looks spatially. Key Points: Radio‐frequency noise spatial correlation functions were calculated for three different neighborhoods in Boston, MassachusettsGood theoretical agreement suggests the noise field is well described by a random network of point sources radiating with a 1/r behavior [ABSTRACT FROM AUTHOR]

Purpose: To employ optimal control for the numerical design of Chemical Exchange Saturation Transfer (CEST) saturation pulses to maximize contrast and stability against B0$$ {\mathrm{B}}_0 $$ inhomogeneities. Theory and Methods: We applied an optimal control framework for the design pulse shapes for CEST saturation pulse trains. The cost functional minimized both the pulse energy and the discrepancy between the corresponding CEST spectrum and the target spectrum based on a continuous radiofrequency (RF) pulse. The optimization is subject to hardware limitations. In measurements on a 7 T preclinical scanner, the optimal control pulses were compared to continuous‐wave and Gaussian saturation methods. We conducted a comparison of the optimal control pulses with Gaussian, block pulse trains, and adiabatic spin‐lock pulses. Results: The optimal control pulse train demonstrated saturation levels comparable to continuous‐wave saturation and surpassed Gaussian saturation by up to 50 % in phantom measurements. In phantom measurements at 3 T the optimized pulses not only showcased the highest CEST contrast, but also the highest stability against field inhomogeneities. In contrast, block pulse saturation resulted in severe artifacts. Dynamic Bloch‐McConnell simulations were employed to identify the source of these artifacts, and underscore the B0$$ {\mathrm{B}}_0 $$ robustness of the optimized pulses. Conclusion: In this work, it was shown that a substantial improvement in pulsed saturation CEST imaging can be achieved by using Optimal Control design principles. It is possible to overcome the sensitivity of saturation to B0 inhomogeneities while achieving CEST contrast close to continuous wave saturation. [ABSTRACT FROM AUTHOR]

Summary: Radio frequency (RF) energy harvesting (EH) for wireless networks provides a green and sustainable solution and offers an energy‐efficient system. It is most crucial for fulfilling the power requirement of the rising number of low‐powered wireless devices and achieving sustainable development goals (SDG). It ensures the longevity of devices in the network even at inaccessible remote locations. Such RF‐EH‐based mechanisms are utilized in simultaneous wireless information and power transfer (SWIPT) systems. Most of the prevailing studies have analyzed the SWIPT system over conventional fading channels. However, due to the higher rate requirements, the current paradigm shift in frequency usage shifts towards the GHz band, which also offers better EH efficiency. Hence, SWIPT system analysis over the channel that is suitable for mm‐wave signal propagation is dealt with in this study. This study evaluates SWIPT performance over fluctuating two‐ray (FTR) fading channel that is crucial since it provides the best fit for characterizing GHz signal and also provides a generalized framework for most of the conventional fading channels. This study presents new analytical results assuming time switch relaying (TSR) protocol with (i) amplify and forward (AF) and (ii) decode and forward (DF) relaying. The results are also analyzed for H branches maximal ratio combining (MRC) diversity technique and evaluated the diversity gain for both AF and DF relays. The effectiveness of the system is measured in terms of system outage probability (SOP) to envisage the reliability of SWIPT based system. This work presents the simulation and modeling of such system and its obtained results are validated by Monte Carlo simulations for their accuracy. [ABSTRACT FROM AUTHOR]

Purpose: We propose and evaluate multiphoton parallel transmission (MP‐pTx) to mitigate flip angle inhomogeneities in high‐field MRI. MP‐pTx is an excitation method that utilizes a single, conventional birdcage coil supplemented with low‐frequency (kHz) irradiation from a multichannel shim array and/or gradient channels. SAR analysis is simplified to that of a conventional birdcage coil, because only the radiofrequency (RF) field from the birdcage coil produces significant SAR. Methods: MP‐pTx employs an off‐resonance RF pulse from a conventional birdcage coil supplemented with oscillating z$$ z $$‐directed fields from a multichannel shim array and/or the gradient coils. We simulate the ability of MP‐pTx to create uniform nonselective brain excitations at 7 T using realistic B1+$$ {\mathrm{B}}_1^{+} $$ and ΔB0$$ \Delta {\mathrm{B}}_0 $$ field maps. The RF, shim array, and gradient waveform's amplitudes and phases are optimized using a genetic algorithm followed by sequential quadratic programming. Results: A 1 ms MP‐pTx excitation using a 32‐channel shim array with current constrained to less than 50 Amp‐turns reduced the transverse magnetization's normalized root‐mean‐squared error from 29% for a conventional birdcage excitation to 6.6% and was nearly 40% better than a 1 ms birdcage coil 5 kT‐point excitation with optimized kT‐point locations and comparable pulse power. Conclusion: The MP‐pTx method resembles conventional pTx in its goals and approach but replaces the parallel RF channels with cheaper, low‐frequency shim channels. The method mitigates high‐field flip angle inhomogeneities to a level better than 3 T CP‐mode and comparable to 7 T pTx while retaining the straightforward SAR characteristics of conventional birdcage excitations, as low‐frequency shim array fields produce negligible SAR. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusion Magnetic resonance imaging (MRI) is a rapidly evolving modality, generally considered safe due to lack of ionising radiation. While MRI technology and techniques are improving, many of the safety concerns remain the same as when first established. Patient thermal injuries are the most frequently reported adverse event, accounting for 59% of MRI incidents to the Food and Drug Administration (FDA). Surveys indicate many incidents remain unreported. Patient thermal injuries are preventable and various methods for their mitigation have been published. However, recommendations can be variable, fragmented and confusing.The aim of this systematic review was to synthesise the evidence on MRI safety and associated skin injuries and offer comprehensive recommendations for radiographers to prevent skin thermal injuries.Four journal databases were searched for sources published January 2010–May 2023, presenting information on MRI safety and thermal injuries.Of 26,801 articles returned, after careful screening and based on the eligibility criteria, only 79 articles and an additional 19 grey literature sources were included (n = 98). Included studies were examined using thematic analysis to determine if holistic recommendations can be provided to assist in preventing skin burns. This resulted in three simplified recommendations: Remove any electrically conductive items Insulate the patient to prevent any conductive loops or contact with objects Communicate regularly By implementing the above recommendations, it is estimated that 97% of skin burns could be prevented. With thermal injuries continuing to impact MRI safety, strategies to prevent skin burns and heating are essential. Assessing individual risks, rather than blanket policies, will help prevent skin thermal injuries occurring, improving patient care. [ABSTRACT FROM AUTHOR]