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Radio-Frequency Interference (RFI) has a large impact on the business of commercial satellites communications and will have an increasingly important role in the next years and decades due to the spread of the launched spacecraft population. This paper presents the current state-of-the-art for Space Traffic Management -related RFI from a regulatory point of view, with regards to preventing and correcting harmful interference, linked to the International Telecommunication Union, and from a technical point of view, with technical procedures, workflows and innovative technology solutions for preventing and mitigating RFI. Finally, emerging technology trends and future directions are presented. • Radio-Frequency Interference has a large impact on satellite communications. • The regulatory processes need to be re-assessed for increased traffic. • Operators need to geolocate the RF source and to quickly solve RFI-related issues. • Many innovative technologies are available to support mitigation. • Emerging trends and new technologies can serve to mitigate the issue. [ABSTRACT FROM AUTHOR]

Radio-frequency identification technology finds extensive use in various industrial applications, including those involving metallic surfaces. The integration of radio-frequency identification systems with metal surfaces, such as those found in the automotive sector, presents distinct challenges that can notably affect system efficacy due to metal's tendency to reflect electromagnetic waves, thus degrading the functionality of conventional radio-frequency identification tags. This highlights the importance of conducting research into academic publications and patents to grasp the current advancements and challenges in this field, aiming to improve the applications of radio-frequency identification tags technology on metal. Consequently, this research undertakes a concise review of both the literature and patents exploring radio-frequency identification technology's use for on-metal tags, utilizing resources like Google Scholar and Google Patents. The research categorized crucial aspects such as tag flexibility, operating frequency, and geographic origins of the research. Findings highlight China's prominent role in contributing to metal-focused radio-frequency identification tag research, with a considerable volume of articles and patents. In particular, flexible tags and the Ultra-High Frequency range are dominant in both scholarly and patent documents, reflecting their significance in radio-frequency identification technology applications. The research underscores a vibrant area of development within radio-frequency identification technology, with continued innovation driven by specific industrial needs. Despite the noted advances, the presence of a significant percentage of no longer valid patents suggests substantial opportunities for further research and innovation in radio-frequency identification technology for on-metal applications, especially considering the demand for flexible tags and for solutions in systems that offer specialized characteristics or are tailored for specific uses. [ABSTRACT FROM AUTHOR]

A single transistor preamplifier circuit was designed to facilitate electrical detection of mechanical oscillations in nanoelectromechanical systems (NEMSs) at low temperatures. The amplifier was integrated in the close vicinity of the nanowire inside the cryostat to minimize cabling load and interference. The function of the circuit was impedance conversion for current flow measurements in NEMSs with a high internal resistance. The circuit was tested to operate at temperatures as low as 5 K and demonstrated the ability to detect oscillations in double-clamped bismuth selenide nanowires upon excitation by a 0.1 MHz–10 MHz AC signal applied to a mechanically separated gate electrode. A strong resonance frequency dependency on temperature was observed. A relatively weak shift in the oscillation amplitude and resonance frequency was measured when a DC bias voltage was applied to the gate electrode at a constant temperature. [ABSTRACT FROM AUTHOR]

Radio-frequency identification technology finds extensive use in various industrial applications, including those involving metallic surfaces. The integration of radio-frequency identification systems with metal surfaces, such as those found in the automotive sector, presents distinct challenges that can notably affect system efficacy due to metal’s tendency to reflect electromagnetic waves, thus degrading the functionality of conventional radio-frequency identification tags. This highlights the importance of conducting research into academic publications and patents to grasp the current advancements and challenges in this field, aiming to improve the applications of radio-frequency identification tags technology on metal. Consequently, this research undertakes a concise review of both the literature and patents exploring radio-frequency identification technology’s use for on-metal tags, utilizing resources like Google Scholar and Google Patents. The research categorized crucial aspects such as tag flexibility, operating frequency, and geographic origins of the research. Findings highlight China’s prominent role in contributing to metal-focused radio-frequency identification tag research, with a considerable volume of articles and patents. In particular, flexible tags and the Ultra-High Frequency range are dominant in both scholarly and patent documents, reflecting their significance in radio-frequency identification technology applications. The research underscores a vibrant area of development within radio-frequency identification technology, with continued innovation driven by specific industrial needs. Despite the noted advances, the presence of a significant percentage of no longer valid patents suggests substantial opportunities for further research and innovation in radio-frequency identification technology for on-metal applications, especially considering the demand for flexible tags and for solutions in systems that offer specialized characteristics or are tailored for specific uses.

Thermotherapy is a frequently used treatment to destroy malignant tumour. The procedure is carried-out using various techniques like radio frequency, laser, focused ultrasound, and microwaves to elevate the desired temperature at targeted tissues. However, it becomes indispensable to note that the impact of the high temperatures also expands to the peripherals of the targeted tissues and can harm the surrounding healthy tissue. This paper aims to find the temperature distribution in tumour tissue during the process and draw the corresponding graphical representation. A five-tine trocar has used to raise the temperature at the centre of the targeted tissue as much as to destroy the tumour tissue. A mathematical model based on the hyperbolic bioheat equation has been formulated and solved by variable separable method after converting the devised equation into dimensionless form. The heat waves make a significant contribution in the propagation of heat at high temperatures therefore, this paper can be viewed as an improvement of the models based on parabolic Penne’s bioheat equation. The results are helpful in estimating the temperature distribution on and around the targeted tissue and hence the therapist can be guided to prevent injuries during the treatment of therapeutic treatments.

Ion thrusters have acquired extensive applications in the space industry with their advantages of high efficiency, high specific impulse, and long lifetime. To operate a radio-frequency (RF) ion thruster successfully, a high-frequency current must be generated to facilitate the discharge of inductively coupled plasma. In this study, with support of trial and error, it is discovered that the thrust performance of an RF ion thruster depends on not only the RF power but also on other critical parameters, such as the propellant flow rate, ion grids voltages, and RF input power. A surrogate model, namely – the Kriging model, is employed to simplify the estimation and optimization of thrust performance. The thrust and specific impulse are selected to be the crucial metrics for used Kriging models for categorizing all types of propulsions. On the basis of Kriging model simulations, the designed RF ion thruster can achieve a thrust of 1.9 mN, a specific impulse of 1649.5 s, and a thrust efficiency of 48% under a propellant flow rate of 4 sccm, grids' voltage difference of 2500 V, and an RF input power of 40 W. • Kriging model was to simplify the optimization of radio-frequency ion thrust performance. • Thrust performance of RIT depends on the radio-frequency power and other parameters. • The optimal RIT can achieve a thrust of 1.9 mN and a specific impulse of 1649.5 s. • The resulting thrust efficiency fulfills 48% under a propellant flow rate of 4 sccm. [ABSTRACT FROM AUTHOR]

Yanping Liang, Lili Li Department of Dermatology, People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, People’s Republic of ChinaCorrespondence: Lili Li, Department of Dermatology, People’s Hospital of Guangxi Zhuang Autonomous Region, 6 Taoyuan Road, Nanning, 530021, People’s Republic of China, Tel +8618777190925, Email 18777190925@163.comIntroduction: Postacne erythema, also referred to as postinflammatory erythema, is a common sequela in acne patients. At present, there is no specific treatment for postacne erythema, and some treatment drugs can even aggravate facial erythema.Objective: Our research sought to evaluate the efficacy of a combination therapy of LED red and blue light, radiofrequency (RF) and intense pulsed light (IPL) for the treatment of postacne erythema.Methods: Patients were treated with red and blue light for 2 weeks, followed by RF for 4 treatments over 8 weeks. Finally, patients were treated with intense pulsed light for 16 weeks. Therapeutic outcomes were evaluated by erythema index, postacne erythema severity grading and clinical photography.Results: After 3 stages of treatment, the percentage of excellent subjects was 79.2%, the percentage of good subjects was 17.2%, and the total effective rate was 96.4%. The mean erythema index decreased from 496.17± 79.11 to 89.32± 81.58 (p< 0.01) after treatment. The postacne erythema lesions were rated clear in 22.4%, faint erythema in 74.4%, dull red in 2.8% and deep red only in 0.4% of subjects after three-stage treatments.Conclusion: Our results show that the combination of red and blue light therapy, RF therapy and IPL therapy is more effective than other treatments reported for facial postacne erythema.Keywords: postacne erythema, red and blue light, radio-frequency, intense pulsed light

Can the combination of computer aided food engineering and electro-heating applications contribute to food processing sustainability? To what United Nations Sustainable Development Goal (SDG) this combination could contribute? Those are the questions addressed in this perspective. SDG7 is aimed to ensure the access to affordable, reliable, and sustainable and modern energy for all. According to World Bank, ensuring access to modern food cooking solutions is a key component to achieving for SDG7, and -since cooking is mainly based on heating processing- also the access to modern food heating solutions must be considered as a key component to achieving for SDG7. Electro-heating applications (EHA) in food processing include all processes using the interaction of a food material or product with an electromagnetic field, as in microwave, radio-frequency, and moderate electric fields processing. These technologies involve the use of electrical and -more recently- electronic circuits and require professional figures in their design. As result, the installation cost of these technologies is way higher than installation cost for heating processes using fossil sources, as fuel for fire boilers, as an example. Furthermore, at industrial level, these technologies may require ad-hoc design. Consequently, the food processing industry is quite slow in embracing such technologies along the productive lines. Computer aided food engineering (CAFE) has been recognized as valuable approach to shifts the paradigm from trial-and-error-based design to model-based design, using digital tools for the virtual representation of a food product or process, predicting the behavior of it. The combination of CAFE and EHA is the only way to help the food industry to embrace sustainability in most operations in which the heat transfer is involved. This paper presents a viewpoint on the challenges and opportunity to combine CAFE and EHAs as contribution to food processing sustainability.

In this article, based on the developed methodology, the stages of designing two designs of high-performance radio-frequency single-pole single-throw microelectromechanical switches are investigated. These radio-frequency microelectromechanical switches are designed to operate at a central resonant frequency of 3.6 GHz and 3.4 GHz, respectively, as well as to work both in mobile communication devices and in the design of the architecture of 5G mobile networks, in particular in arrays of integrated antennas and radio-frequency interface modules. The manufacture and study of two designed structures are researched. For the first manufactured experimental sample in the open state the insertion loss is no more than −0.69 dB and the reflection loss is −28.35 dB, and in the closed state the isolation value is at least −54.77 dB at a central resonant frequency of 3.6 GHz. For the second in the open state the value of the insertion loss is no more than −0.67 dB and the reflection loss is −20.7 dB, and in the closed state the isolation value is not less than −52.13 dB at the central resonant frequency of 3.4 GHz. Both manufactured experimental samples are characterized by high linearity, as well as a small value of contact resistance in the closed state. [ABSTRACT FROM AUTHOR]

A single transistor preamplifier circuit was designed to facilitate electrical detection of mechanical oscillations in nanoelectromechanical systems (NEMSs) at low temperatures. The amplifier was integrated in the close vicinity of the nanowire inside the cryostat to minimize cabling load and interference. The function of the circuit was impedance conversion for current flow measurements in NEMSs with a high internal resistance. The circuit was tested to operate at temperatures as low as 5 K and demonstrated the ability to detect oscillations in double-clamped bismuth selenide nanowires upon excitation by a 0.1 MHz–10 MHz AC signal applied to a mechanically separated gate electrode. A strong resonance frequency dependency on temperature was observed. A relatively weak shift in the oscillation amplitude and resonance frequency was measured when a DC bias voltage was applied to the gate electrode at a constant temperature.

Aim. To validate the National Danish Ablation Database (NDAD) by investigating to what extent data in NDAD correspond to medical records. Type of study. Non-blinded, registry-based, retrospective, validation study. Material and methods. A sample of patients who underwent ablation for atrial fibrillation in Denmark between 1 January 2016 and 31 December 2016 were included. By utilizing medical records as gold standard, positive predictive (PPV) and negative predictive values (NPV) for NDAD were assessed and presented as five main categories: arrhythmia characteristics, demographics, cardiac history, complications, and medication. PPV's and NPV's exceeding 90% were considered as high agreement. Results. 597 patients (71.0% males) were included in the study. Median age was 63.1 (IQR: 54.9–68.4) years. The median PPV and NPV estimates across all variables were respectively 90.4% (95% CI: 68%–95.2%) (PPV) and 99.4% (95% CI: 98.4%–99.8%) (NPV) at baseline, and 91.7% (95% CI: 67.4%–95.4%) (PPV) and 99.3% (98.2%–99.3%) (NPV) at follow-up. Conclusion. The data registered in NDAD agrees to a great extent with the patients' medical records, suggesting NDAD is a database with high validity. As a result of low complication rate, the PPV- and NPV-estimates among complication variables were prone to somewhat greater uncertainty compared to the rest. [ABSTRACT FROM AUTHOR]

Multiple Electrostatic Quadrupole Array Linear Accelerators (MEQALACs) provide an opportunity to realize compact radio- frequency (RF) accelerator structures that can deliver very high beam currents. MEQALACs have been previously realized with acceleration gap distances and beam aperture sizes of the order of centimeters. Through advances in Micro-Electro-Mechanical Systems (MEMS) fabrication, MEQALACs can now be scaled down to the sub-millimeter regime and batch processed on wafer substrates. In this paper we show first results from using three RF stages in a compact MEMS-based ion accelerator. The results presented show proof-of-concept with accelerator structures formed from printed circuit boards using a 3 × 3 beamlet arrangement and noble gas ions at 10 keV. We present a simple model to describe the measured results. We also discuss some of the scaling behaviour of a compact MEQALAC. The MEMS-based approach enables a low-cost, highly versatile accelerator covering a wide range of currents (10 μA to 100 mA) and beam energies (100 keV to several MeV). Applications include ion-beam analysis, mass spectrometry, materials processing, and at very high beam powers, plasma heating.

Partial discharge (PD) monitoring of electrical substations could provide early warning of insulation failures. Among the various technologies, Radio Frequency (RF) based PD monitoring system could be a promising solution. The RF-based monitoring system detects PD sources in the substation and can also localise the PD sources. The time difference of arrival (TDOA) based PD localisation system primarily require arrival time (AT) of the impulsive RF signal. Though many localisation algorithms have been proposed in the recent past to overcome the TDOA estimation errors, less attention has been given to the accurate estimation of RF PD signal arrival time. This paper presents the AT's automatic labelling in the RF PD signal using Bi-Long Short-Term Memory (Bi-LSTM) network applied on the continuous wavelet transformed (CWT) signal. Further, it also shows PD signal augmentation to overcome the problem of limited representative training data set. The behavior of the radiated RF signals is influenced by many factors and has almost stochastic characteristics. The proposed system has been validated with laboratory-based experimental signals and the data set obtained from different electrical substations. The results show that the improved performance is obtained from the combination of a multilayer Bi-LSTM model and an augmented training set. [ABSTRACT FROM AUTHOR]

Using radiofrequency energy for closure of the patent ductus arteriosus (PDA) has been reported by us previously. In this article we report the early and late outcome of the first group in whom patent ductus arteriosus has been occluded with radiofrequency. Six children with PDA were enrolled. The procedure was successful in five cases and transient hoarseness was observed in 2 cases as the only complication.

In this article, based on the developed methodology, the stages of designing two designs of high-performance radio-frequency single-pole single-throw microelectromechanical switches are investigated. These radio-frequency microelectromechanical switches are designed to operate at a central resonant frequency of 3.6 GHz and 3.4 GHz, respectively, as well as to work both in mobile communication devices and in the design of the architecture of 5G mobile networks, in particular in arrays of integrated antennas and radio-frequency interface modules. The manufacture and study of two designed structures are researched. For the first manufactured experimental sample in the open state the insertion loss is no more than −0.69 dB and the reflection loss is −28.35 dB, and in the closed state the isolation value is at least −54.77 dB at a central resonant frequency of 3.6 GHz. For the second in the open state the value of the insertion loss is no more than −0.67 dB and the reflection loss is −20.7 dB, and in the closed state the isolation value is not less than −52.13 dB at the central resonant frequency of 3.4 GHz. Both manufactured experimental samples are characterized by high linearity, as well as a small value of contact resistance in the closed state.

Untethered, wirelessly interconnected devices are becoming pervasive in today’s society forming the Internet of Things. These autonomous devices and systems continue to scale to reduced dimensions at the millimeter scale and below, presenting major challenges to how we provide power to these devices. This article surveys existing approaches to harvest energy from the ambient or externally supplied sources including radio-frequency, optical, mechanical, thermal, nuclear, chemical, and biological modalities to provide electrical power for micro- and nano-systems. The outlook for scaling these energy conversion approaches to small dimensions is discussed in the context of both existing technologies and possible future nanoscience developments.

Featured Application: The author provides recent research and future challenge of RF bio and gas sensing platforms for wireless health care system applications. In the past decade, graphene has been widely researched to improve or overcome the performance of conventional radio-frequency (RF) nanodevices and circuits. In recent years, novel RF bio and gas sensors based on graphene and its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), have emerged as new RF sensing platforms using a wireless remote system. Although the sensing schemes are still immature, this review focuses on the recent trends and advances of graphene and GO (rGO)-based RF bio and gas sensors for a real-time and continuous wireless health care system. [ABSTRACT FROM AUTHOR]

Abstract Wearable sensors promise to transform human understanding of body state. However, despite many wearable sensor modalities that exist, few demonstrate the raw capabilities required for many emerging healthcare applications—passivity (and microelectronics‐free), wireless readout, long‐term operation, and specificity. Hydrogel‐interlayer radio‐frequency resonators are demonstrated as a versatile platform for passive and wireless biosensing. Fabricated using a simple vinyl cutter, the base resonator is composed of unanchored, broad‐side coupled coils interceded by multifunctional hydrogels—such resonators are tuned to be sensitive to specific analytical or physical signals by modifying hydrogel composition. These resonators are transformed into near‐field communication (NFC) sensor circuits through the simple attachment of an LED. These enable direct quantification of sensor state by cellphone and eye with no specialized electronics required. Resonator arrays are finally fused with silicone to form soft, wireless sensor skins that enable co‐readout of analytical to physical signals while molded to human subjects. Such low‐cost, accessible platforms can integrate with environments in transformative ways, enabling new applications in wireless sensing.

The study and control of resonant instabilities in magnetized plasmas is of fundamental interest over a wide range of applications from industrially relevant plasmas to plasma sources for spacecraft propulsion. In this work electrostatic probes were employed to measure a 4–20 kHz instability in the ion saturation current downstream of an electric double layer (DL) in an expanding helicon plasma source. The amplitude and frequency of the instability were found to vary in inverse proportion to the operating argon gas pressure (0.2–0.6 mTorr) and in direct proportion to the applied rf power (100–600 W) and applied solenoid current (3–8 A). A spatially resolved characterization of the maximum instability amplitude determined two radial maxima, corresponding to the locations of most positive radial ion density gradient. Control and inhibition of the instability were achieved through the application of a kHz voltage amplitude modulation to the 13.56 MHz radio-frequency (rf) power supplied to the helicon antenna. Through the application of voltage amplitude modulations in the frequency range 2–12 kHz the instability was reduced by up to 65%, exhibiting a greater reduction at higher applied modulation frequencies. This effect is described through a variation in the radial ion density gradient via asymmetrically attenuated ion acoustic density perturbations induced by the applied voltage modulation. The application of voltage amplitude modulations has been demonstrated as a potential control mechanism for density gradient driven instabilities in magnetized plasmas.

Objective(s): Nowadays, the electromagnetic field-emitting devices are used routinely in our lives. Controversial reports exist concerning the effects of mobile radiofrequency (RF) on different parts of the body, especially stress hormones. The main goal of the present work was to study the long-term effects of mobile RF900 MHz exposure with special focus on the adrenal gland pathophysiology and function. Materials and Methods: Adult male Wistar rats were exposed to mobile RF 6 hr daily for 4–8 weeks. Intact and switched-off exposed animals were considered as controls. Plasma ACTH and cortisol levels were measured by the ELISA method. At the end of the experiment, a histological study was done on adrenal gland and brain tissues by hematoxylin and eosin staining. The thickness of the fasciculate layer of the adrenal gland, and its cell count and perimeter were measured using the Fiji software. Results: Enhanced plasma ACTH and cortisol levels were found after prolonged exposure to mobile RF. The fasciculata layer of adrenal cortex eventually thickened following mobile RF radiation. While the number of cells in zona fasciculata remained constant, the cell size and perimeter increased during RF exposure. Finally, we found that vacuolization in brain tissue and the number and size of vacuoles considerably increased during two months of RF exposure. Conclusion: Cell phone RF exposure induced significant hormonal and structural changes in adrenal gland and brain tissues. Therefore, the public should be aware and limit their exposure as much as possible.

Satellite based communication either in GEO or LEO based system are prominently employed for voice, video, data communication. Demand of more traffic necessitates the data rate of satellite to be enhanced which can be implemented by the proper choice of modulation scheme. Presently ground systems are also wireless based which include direct broadcast satellite (DBS),television service, wireless local area networks (WLANs), global positioning satellite (GPS), radio-frequency identification systems which is either point-to-point or point-to-multipoint. Modern day communication systems are digital; based rather than analog to have better noise immunity. Further with the limited spectrum availability the choice of modulation scheme plays an important role for faithful transmission of the signal. The digital communication can be categorized as Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK) whereas for higher bit data rate Phase Shift Keying (PSK) such as BPSK, QPSK and OQPSK are employed. This article overview of various modulation schemes which are employed in satellite communication apart from its selection criteria along with the concept of bit error rate. [ABSTRACT FROM AUTHOR]

In this study, the total electromagnetic dose, i.e., the combined dose from fixed antennas and mobile devices, was estimated for a number of hypothetical network topologies for implementation in Switzerland to support the deployment of fifth generation (5G) mobile communication systems while maintaining exposure guidelines for public safety. In this study, we consider frequency range 1 (FR1) and various user scenarios. The estimated dose in hypothetical 5G networks was extrapolated from measurements in one of the Swiss 4G networks and by means of Monte Carlo analysis. The results show that the peak dose is always dominated by an individual's mobile phone and, in the case of non-users, by the bystanders' mobile phones. The reduction in cell size and the separation of indoor and outdoor coverage can substantially reduce the total dose by >10 dB. The introduction of higher frequencies in 5G mobile networks, e.g., 3.6 GHz, reduces the specific absorption rate (SAR) in the entire brain by an average of −8 dB, while the SAR in the superficial tissues of the brain remains locally constant, i.e., within ±3 dB. Data from real networks with multiple-input multiple-output (MIMO) were not available; the effect of adaptive beam-forming antennas on the dose will need to be quantitatively revisited when 5G networks are fully established. [ABSTRACT FROM AUTHOR]

A comparative study of capacitively coupled radio frequency discharges was conducted using 2-D particle-in-cell simulation (PIC) and 2-D fluid plasma simulation. The selected scenario was a planar discharge with a 3-cm gap operated in helium, at a gas pressure of 400 Pa, with a driving voltage between 120 and 400 V at 3.2 MHz. The solvers were adapted to a 1-D problem by using periodic boundary conditions perpendicular to the gap, and the models included ion impact-induced secondary electron emission from the electrodes. A good agreement was obtained between the results of both solvers, with less than 23% deviation in the peak plasma density. For the studied range of secondary emission coefficients, $0.08 < \gamma _{\mathrm {se}} < 0.378$ , it was found that a common transition point between “alpha” and “gamma” modes occurs at $V_{\mathbf {rf}} \sim 250$ V. Since the simulation results were shown to be less sensitive to the secondary emission coefficient below this transition voltage, these results can serve as a standard benchmark for plasma codes. [ABSTRACT FROM AUTHOR]

The rf R&D program for high-gradient, low frequency cavities to be used in muon cooling systems is underway in the Fermilab MUCOOL Test Area. Cavities at 805 and 201 MHz are used for tests of conditioning techniques, surface modification and breakdown studies. This work has the Muon Ionization Cooling Experiment (MICE) as its immediate goal and efficient muon cooling systems for neutrino sources and muon colliders as the long term goal. We study breakdown and dark current production under a variety of conditions.

This paper proposes a Tunnel FET (TFET)-based power management circuit (PMC) for ultra-low power RF energy harvesting applications. In contrast with conventional thermionic devices, the band-to-band tunneling mechanism of TFETs allows a better switching performance at sub-0.2 V operation. As a result, improved efficiencies in RF-powered circuits are achieved, thanks to increased rectification performance at low power levels and to the reduced energy required for a proper PMC operation. It is shown by simulations that heterojunction TFET devices designed with III-V materials can improve the rectification process at received power levels below -20 dBm (915 MHz) when compared to the application of homojunction III-V TFETs and Si FinFETs. For an available power of -25 dBm, the proposed converter is able to deliver 1.1 μW of average power (with 0.5 V) to the output load with a boost efficiency of 86%.

Plasma-based surface modification is recognized as an effective way to activate biomaterial surfaces, and modulate their interactions with cells, extracellular matrix proteins, and other materials. However, treatment of a luminal surface of a tubular scaffold remains non-trivial to perform in small diameter tubes. Polyvinyl alcohol (PVA) hydrogel, which has been widely used for medical applications, lacks functional groups to mediate cell attachment. This poses an issue for vascular applications, as endothelialization in a vascular graft lumen is crucial to maintain long term graft patency. In this study, a Radio Frequency Glow Discharges (RFGD) treatment in the presence of NH3 was used to modify the luminal surface of 3-mm diameter dehydrated PVA vascular grafts. The grafted nitrogen containing functional groups demonstrated stability, and in vitro endothelialization was successfully maintained for at least 30 days. The plasma-modified PVA displayed a higher percentage of carbonyl groups over the untreated PVA control. Plasma treatment on PVA patterned with microtopographies was also studied, with only the concave microlenses topography demonstrating a significant increase in platelet adhesion. Thus, the study has shown the possibility of modifying a small diameter hydrogel tubular scaffold with the RFGD plasma treatment technique and demonstrated stability in ambient storage conditions for up to 30 days.

The electrical properties of soil at low radio-frequencies are important for engineering applications. In this work the effects of excitation frequency (42 Hz-1 MHz) as well as soil characteristics and conditions on the electrical properties of soil are experimentally investigated using remolded soil samples. Several sandy soils were tested with variable water content (dry up to saturation) using guarded two-electrode arrangements. A method is proposed based on the Nyquist plot to estimate the critical frequency above which measurements of the electrical properties of wet soil are free from electrode polarization effects. The latter result in extremely high real permittivity values, which do not correspond to the response of soil. The critical frequency is higher for smaller grain size and higher water content and varies according to a power law with soil power-frequency conductivity. The real and (effective) imaginary relative permittivity decrease with increasing frequency whereas the effective conductivity increases; this is attributed to the distributed relaxation of the interfacial polarization mechanism associated with the particulate nature of soil. The values of soil electrical properties increase with increasing water content and decreasing grain size (increasing specific surface) as a consequence of enhanced polarization and conduction phenomena. The effective imaginary permittivity varies with frequency according to a power law with an exponent approximately −1; the multiplier coefficient of this law expresses losses and has been formulated as a function of the degree of saturation and soil specific surface. [ABSTRACT FROM AUTHOR]

Objectives: To assess the safety and effectiveness of in‐office bipolar radiofrequency treatment of nasal valve obstruction Study Design: Prospective, nonrandomized, multicenter case series Methods: Adult patients with a Nasal Obstruction Symptom Evaluation scale (NOSE) score ≥60 were selected. Patients were clinically diagnosed with dynamic or static internal nasal valve obstruction as primary or significant contributor to obstruction and were required to have a positive response to nasal mechanical dilators or lateralization maneuvers. Bilateral radio‐frequency treatment was applied intranasally using a novel device, under local anesthesia in a single session. Safety and tolerance were assessed by event reporting, inspection, and Visual Analogue Scale (VAS) for pain. Efficacy was determined using the NOSE score and patient‐reported satisfaction survey at 26 weeks. Results: Fifty patients were treated. No device or procedure‐related serious adverse events occurred. Soreness, edema, and crusting resolved by 1 month. The mean baseline NOSE score was 79.9 (SD 10.8, range 60–100), and all had severe or extreme obstruction. At 26 weeks, mean NOSE score was 69% lower at 24.7 (P <.0001) with 95% two‐sided confidence intervals 48.5 to 61.1 for decrease. The decrease in NOSE score did not differ significantly between patients who did or did not have prior nasal surgery. Patient satisfaction mean by survey was 8.2 of 10. Conclusion: In office treatment of internal nasal valve obstruction using a bipolar radiofrequency device is safe and well‐tolerated. Nasal obstruction, as assessed using the NOSE questionnaire at 26 weeks, was markedly improved with high patient satisfaction. Level of Evidence: 2b, prospective cohort [ABSTRACT FROM AUTHOR]

Abstract AlGaN/GaN/Si high electron mobility transistors (HEMTs) developed by molecular beam epitaxy (MBE) are studied with several methods for characterization, the most utilized are direct-current and radio-frequency measurements, to see power and microwave performance of components. The increase in these parameters is not based just with on improvement technological for example, decrease of length gate (Lg) and passivation. For sure, another very important point is to reduce the thickness of barrier while keeping the reduction in the length of gate, in order to reduce the transit time (τ), and consequently access to highest cut-off frequency (F T). For this situation, it's appears a harmful phenomenon of type "punch-through", because of the weak confinement of electrons in the channel. In this paper, the main objective is to show how to reduce this effect. [ABSTRACT FROM AUTHOR]

In the past decade, graphene has been widely researched to improve or overcome the performance of conventional radio-frequency (RF) nanodevices and circuits. In recent years, novel RF bio and gas sensors based on graphene and its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), have emerged as new RF sensing platforms using a wireless remote system. Although the sensing schemes are still immature, this review focuses on the recent trends and advances of graphene and GO (rGO)-based RF bio and gas sensors for a real-time and continuous wireless health care system.

This review paper focuses on radio-frequency (RF) biosensors for real-time and continuous glucose sensing reported in the literature, including our recent research. Diverse versions of glucose biosensors based on RF devices and circuits are briefly introduced, and their performances are compared. In addition, the limitations of the developed RF glucose biosensors are discussed. Finally, we present perspectives on state-of-art RF biosensing chips for point-of-care diagnosis and describe their future challenges.

In this study, the total electromagnetic dose, i.e., the combined dose from fixed antennas and mobile devices, was estimated for a number of hypothetical network topologies for implementation in Switzerland to support the deployment of fifth generation (5G) mobile communication systems while maintaining exposure guidelines for public safety. In this study, we consider frequency range 1 (FR1) and various user scenarios. The estimated dose in hypothetical 5G networks was extrapolated from measurements in one of the Swiss 4G networks and by means of Monte Carlo analysis. The results show that the peak dose is always dominated by an individual’s mobile phone and, in the case of non-users, by the bystanders’ mobile phones. The reduction in cell size and the separation of indoor and outdoor coverage can substantially reduce the total dose by >10 dB. The introduction of higher frequencies in 5G mobile networks, e.g., 3.6 GHz, reduces the specific absorption rate (SAR) in the entire brain by an average of −8 dB, while the SAR in the superficial tissues of the brain remains locally constant, i.e., within ±3 dB. Data from real networks with multiple-input multiple-output (MIMO) were not available; the effect of adaptive beam-forming antennas on the dose will need to be quantitatively revisited when 5G networks are fully established.

Objective(s): Nowadays, the electromagnetic field-emitting devices are used routinely in our lives. Controversial reports exist concerning the effects of mobile radiofrequency (RF) on different parts of the body, especially stress hormones. The main goal of the present work was to study the long-term effects of mobile RF900 MHz exposure with special focus on the adrenal gland pathophysiology and function. Materials and Methods: Adult male Wistar rats were exposed to mobile RF 6 hr daily for 4-8 weeks. Intact and switched-off exposed animals were considered as controls. Plasma ACTH and cortisol levels were measured by the ELISA method. At the end of the experiment, a histological study was done on adrenal gland and brain tissues by hematoxylin and eosin staining. The thickness of the fasciculate layer of the adrenal gland, and its cell count and perimeter were measured using the Fiji software. Results: Enhanced plasma ACTH and cortisol levels were found after prolonged exposure to mobile RF. The fasciculata layer of adrenal cortex eventually thickened following mobile RF radiation. While the number of cells in zona fasciculata remained constant, the cell size and perimeter increased during RF exposure. Finally, we found that vacuolization in brain tissue and the number and size of vacuoles considerably increased during two months of RF exposure. Conclusion: Cell phone RF exposure induced significant hormonal and structural changes in adrenal gland and brain tissues. Therefore, the public should be aware and limit their exposure as much as possible. [ABSTRACT FROM AUTHOR]

The ITER Ion Cyclotron Resonance Heating (ICRH) system is designed to couple to the plasma 20 MW of RF power from two antennas in the 40–55 MHz frequency range during long pulses of up to 3600 s and under various plasma conditions with Edge Localized Modes. Radio-Frequency (RF) contacts are integrated within the ITER ICRH launcher in order to ensure the RF current continuity and ease the mechanical assembly by allowing the free thermal expansion of the Removable Vacuum Transmission Line coaxial conductors during RF operations or during 250 °C baking phases. A material study has been carried out to determine which materials and associated coatings are relevant for RF contacts application in ITER. In parallel, RF tests have been performed with a new prototype of Multi-Contact ® LA-CUT/0,25/0 contacts made of silver-coated CuCrZr louvers. During these tests on a RF vacuum resonator, currents between 1.2 kA and 1.3 kA peak have been reached a few tens of times in steady-state conditions without any visible damage on the louvers. A final 62 MHz pulse ending in a 300 s flat top at 1.9 kA resulted in severe damage to the contact. In addition, a test bed which performs sliding test cycles has been built in order to reproduce the wear of the contact prototype after 30 000 sliding cycles on a 3 mm stroke at 175 °C under vacuum. The silver coating of the louvers is removed after approximately a hundred cycles whilst, to the contrary, damage to the CuCrZr louvers is relatively low. [ABSTRACT FROM AUTHOR]

We have fabricated top-gated ambipolar field-effect transistors (FETs) based on solution-derived carbon nanotube (CNT) network films, and then constructed inverters and ring oscillators (ROs) that can work under supply voltages as low as 0.2 V owing to the high uniformity of the devices. Significant improvements were achieved in the performance of these CNT-based ambipolar FETs and CMOS-like circuits by scaling down the gate length of the CNT FETs and optimizing the device structure and RO layout. In particular, the optimized five-stage RO is shown to present a record high oscillation frequency of up to 17.4 MHz with a propagation time of 5.6 ns at a 12-V working voltage. The CNT film-based ROs were used as carrier-wave generators in radio-frequency systems to demonstrate a complete signal transmission process. These results suggest that CNT thin film-based FETs and integrated circuits may soon find their way to radio-frequency applications with a frequency band of 13.56 MHz. [ABSTRACT FROM AUTHOR]