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Journal articles on the topic 'Radio-Frequency (RF) coils'

Author: Grafiati

Published: 14 March 2023

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1

Truszkiewicz, Adrian, David Aebisher, Zuzanna Bober, Łukasz Ożóg, and Dorota Bartusik-Aebisher. "Radio Frequency MRI coils." European Journal of Clinical and Experimental Medicine 18, no. 1 (2020): 24–27. http://dx.doi.org/10.15584/ejcem.2020.1.5.

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Introduction. Magnetic Resonance Imaging (MRI) coils technology is a powerful improvement for clinical diagnostics. This includes opportunities for mathematical and physical research into coil design. Aim. Here we present the method applied to MRI coil array designs. Material and methods. Analysis of literature and self-research. Results. The coils that emit the radiofrequency pulses are designed similarly. As much as possible, they deliver the same strength of radiofrequency to all voxels within their imaging volume. Surface coils on the other hand are usually not embedded in cylindrical surf

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2

Seo, Jeung-Hoon, Yeunchul Ryu, and Jun-Young Chung. "Simulation Study of Radio Frequency Safety and the Optimal Size of a Single-Channel Surface Radio Frequency Coil for Mice at 9.4 T Magnetic Resonance Imaging." Sensors 22, no. 11 (2022): 4274. http://dx.doi.org/10.3390/s22114274.

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The optimized size of a single-channel surface radio frequency (RF) coil for mouse body images in a 9.4 T magnetic resonance imaging (MRI) system was determined via electromagnetic-field analysis of the signal depth according to the size of a single-channel coil. The single-channel surface RF coils used in electromagnetic field simulations were configured to operate in transmission/reception mode at a frequency of 9.4 T–400 MHz. Computational analysis using the finite-difference time-domain method was used to assess the single-channel surface RF coil by comparing single-channel surface RF coil

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3

Seo, Jeung-Hoon, Young-Seung Jo, Chang-Hyun Oh, and Jun-Young Chung. "A New Combination of Radio-Frequency Coil Configurations Using High-Permittivity Materials and Inductively Coupled Structures for Ultrahigh-Field Magnetic Resonance Imaging." Sensors 22, no. 22 (2022): 8968. http://dx.doi.org/10.3390/s22228968.

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In ultrahigh-field (UHF) magnetic resonance imaging (MRI) system, the RF power required to excite the nuclei of the target object increases. As the strength of the main magnetic field (B0 field) increases, the improvement of the RF transmit field (B1+ field) efficiency and receive field (B1− field) sensitivity of radio-frequency (RF) coils is essential to reduce their specific absorption rate and power deposition in UHF MRI. To address these problems, we previously proposed a method to simultaneously improve the B1+ field efficiency and B1− field sensitivity of 16-leg bandpass birdcage RF coil

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4

Ahmad, Sheikh Faisal, Young Cheol Kim, Ick Chang Choi, and Hyun Deok Kim. "Recent Progress in Birdcage RF Coil Technology for MRI System." Diagnostics 10, no. 12 (2020): 1017. http://dx.doi.org/10.3390/diagnostics10121017.

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The radio frequency (RF) coil is one of the key components of the magnetic resonance imaging (MRI) system. It has a significant impact on the performance of the nuclear magnetic resonance (NMR) detection. Among numerous practical designs of RF coils for NMR imaging, the birdcage RF coil is the most popular choice from low field to ultra-high field MRI systems. In the transmission mode, it can establish a strong and homogeneous transverse magnetic field B1 for any element at its Larmor frequency. Similarly, in the reception mode, it exhibits extremely high sensitivity for the detection of even

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5

Duan, Yunsuo, Tamer S. Ibrahim, Bradley S. Peterson, Feng Liu, and Alayar Kangarlu. "Assessment of a PML Boundary Condition for Simulating an MRI Radio Frequency Coil." International Journal of Antennas and Propagation 2008 (2008): 1–10. http://dx.doi.org/10.1155/2008/563196.

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Computational methods such as the finite difference time domain (FDTD) play an important role in simulating radiofrequency (RF) coils used in magnetic resonance imaging (MRI). The choice of absorbing boundary conditions affects the final outcome of such studies. We have used FDTD to assess the Berenger's perfectly matched layer (PML) as an absorbing boundary condition for computation of the resonance patterns and electromagnetic fields of RF coils. We first experimentally constructed a high-pass birdcage head coil, measured its resonance pattern, and used it to acquire proton phantom MRI image

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6

Aebischer, H. A. "Inductance Formula for Square Spiral Inductors with Rectangular Conductor Cross Section." Advanced Electromagnetics 8, no. 4 (2019): 80–88. http://dx.doi.org/10.7716/aem.v8i4.1074.

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Planar spiral coils are used as inductors in radio frequency (RF) microelectronic integrated circuits (IC’s) and as antennas in both radio frequency identification (RFID) and telemetry systems. They must be designed to a specified inductance. From the literature, approximate analytical formulae for the inductance of such coils with rectangular conductor cross section are known. They yield the direct current (DC) inductance, which is considered as a good approximation for inductors in RF IC’s up to the GHz range. In principle, these formulae can simplify coil design considerably. But a recent c

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7

Hong, Seon-Eui, Sukhoon Oh, and Hyung-Do Choi. "RF Exposure Assessment for Various Poses of Patient Assistant in Open MRI Environment." Applied Sciences 11, no. 11 (2021): 4967. http://dx.doi.org/10.3390/app11114967.

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In this study, the radio-frequency (RF) energy exposure of patient assistants was assessed for an open magnetic resonance imaging (MRI) system based on numerical computations of the head and body RF coil. Various poses of the patient assistants were defined to see how poorly they affected the RF energy exposure. For the assessments, the peak spatial-averaged specific absorption rate (SAR) levels were carefully compared with each patient assistant pose based on the finite-difference time domain calculations of RF coil models when the patient was placed in such coils in a 0.3 Tesla open MRI syst

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8

Ramsaroop, Neetu, and Oludayo O. Olugbara. "Wireless Power Transfer Using Harvested Radio Frequency Energy with Magnetic Resonance Coupling to Charge Mobile Device Batteries." Applied Sciences 11, no. 16 (2021): 7707. http://dx.doi.org/10.3390/app11167707.

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This research paper presents the design of a wireless power transfer (WPT) circuit integrated with magnetic resonance coupling (MRC) and harvested radio frequency (RF) energy to wirelessly charge the battery of a mobile device. A capacitor (100 µF, 16 V) in the RF energy harvesting circuit stored the converted power, and the accumulated voltage stored in the capacitor was 9.46 V. The foundation of the proposed WPT prototype circuit included two coils (28 AWG)—a transmitter coil, and a receiver coil. The transmitter coil was energized by the alternating current (AC), which produced a magnetic f

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9

Lu, Ming, Xiaoyang Zhang, Shuyang Chai, and Xinqiang Yan. "Improving Specific Absorption Rate Efficiency and Coil Robustness of Self-Decoupled Transmit/Receive Coils by Elevating Feed and Mode Conductors." Sensors 23, no. 4 (2023): 1800. http://dx.doi.org/10.3390/s23041800.

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Self-decoupling technology was recently proposed for radio frequency (RF) coil array designs. Here, we propose a novel geometry to reduce the peak local specific absorption rate (SAR) and improve the robustness of the self-decoupled coil. We first demonstrate that B1 is determined by the arm conductors, while the maximum E-field and local SAR are determined by the feed conductor in a self-decoupled coil. Then, we investigate how the B1, E-field, local SAR, SAR efficiency, and coil robustness change with respect to different lift-off distances for feed and mode conductors. Next, the simulation

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10

Domenick, Robert, Phillip Foreman, David M. Parish, and Donald W. Pettibone. "4882540 Magnetic resonance imaging (MRI) apparatus with quadrature radio frequency (RF) coils." Magnetic Resonance Imaging 8, no. 6 (1990): I. http://dx.doi.org/10.1016/0730-725x(90)90025-w.

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11

Zărnescu, George-Claudiu, Lucian Pîslaru-Dănescu, and Athanasios Tiliakos. "Modular Electromagnetic Transducer for Optimized Energy Transfer via Electric and/or Magnetic Fields." Sensors 23, no. 3 (2023): 1291. http://dx.doi.org/10.3390/s23031291.

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In this paper, a modular electromagnetic transducer that achieves the optimal transfer of energy from the electric and/or magnetic fields is proposed. Both the magnetic field resonance coupling and the influence of the electric field near the copper transducers of the printed circuit board and inside the FR4-type epoxy material are considered. In our printed arrays of flat transducers, we consider face-to-face capacitances for the study of resonance coupling. Because the space between coil turns is almost double the plate thickness, the coplanar capacitance can be ignored for frequencies under

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12

Abuelhaija, Ashraf, and Gameel Saleh. "Dual tuned 1H/31P quadrature microstripline-based transmit/receive switch for 7 Tesla magnetic resonance imaging." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 3 (2022): 2177. http://dx.doi.org/10.11591/ijece.v12i3.pp2177-2183.

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<p><span>A dual tuned transmit/receive (T/R) Switch for 7 tesla magnetic resonance imaging</span> (MRI) that is based on concentric microstripline (MSL) coupler is introduced. The proposed switch is designed using two concentric MSL quadrature couplers on the top and bottom faces of the switch. The switch can be used to handle two frequency signals to/from two radio frequency (RF) coils. In this article, a 1H/31P atomic nuclei are excited. The two MSLs on the upper face of the switch are designed to transmit 298 and 120.6 MHz signals into RF coils, whereas each of the identic

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13

Giovannetti, Giulio, Alessandra Flori, Maria Filomena Santarelli, et al. "Radio Frequency Coils for Hyperpolarized 13C Magnetic Resonance Experiments with a 3T MR Clinical Scanner: Experience from a Cardiovascular Lab." Electronics 10, no. 4 (2021): 366. http://dx.doi.org/10.3390/electronics10040366.

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Hyperpolarized 13C magnetic resonance (MR) is a promising technique for the noninvasive assessment of the regional cardiac metabolism since it permits heart physiology studies in pig and mouse models. The main objective of the present study is to resume the work carried out at our electromagnetic laboratory in the field of radio frequency (RF) coil design, building, and testing. In this paper, first, we review the principles of RF coils, coil performance parameters, and estimation methods by using simulations, workbench, and MR imaging experiments. Then, we describe the simulation, design, and

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14

Qian, Zhongnan, Rui Yan, Zeqian Cheng, Jiande Wu, and Xiangning He. "Magnetic Positioning Technique Integrated with Near-Field Communication for Wireless EV Charging." Energies 13, no. 5 (2020): 1081. http://dx.doi.org/10.3390/en13051081.

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For wireless electric vehicle charging, the relative position of the primary and secondary coils has significant impacts on the transferred power, efficiency and leakage magnetic flux. In this paper, a magnetic positioning method using simultaneous power and data transmission (SWPDT) is proposed for power coil alignment. Four signal coils are installed on the primary coil to detect the secondary coil position. By measuring the positioning signal amplitudes from the four signal coils, the power coil relative position can be obtained. Moreover, all the communication needed in the positioning pro

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15

Chiang, Yen-Chung, Juo-Chen Chen, and Yu-Hsin Chang. "A Study on the Variable Inductor Design by Switching the Main Paths and the Coupling Coils." Electronics 10, no. 15 (2021): 1856. http://dx.doi.org/10.3390/electronics10151856.

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In a radio frequency (RF) system, it is possible to use variable inductors for providing tunable or selective frequency range. Variable inductors can be implemented by the microelectromechanical system (MEMS) process or by using transistors as switches to change the routing of coils or coupling quantities. In this paper, we investigated the design method of a variable inductor by using MOS transistors to switch the main coil paths and the secondary coupled coils. We observed the effects of different metal layers, turn numbers, and layout arrangements for secondary-coupled coils and compared th

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16

Kazemivalipour, Ehsan, Alireza Sadeghi-Tarakameh, Boris Keil, Yigitcan Eryaman, Ergin Atalar, and Laleh Golestanirad. "Effect of field strength on RF power deposition near conductive leads: A simulation study of SAR in DBS lead models during MRI at 1.5 T—10.5 T." PLOS ONE 18, no. 1 (2023): e0280655. http://dx.doi.org/10.1371/journal.pone.0280655.

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Background Since the advent of magnetic resonance imaging (MRI) nearly four decades ago, there has been a quest for ever-higher magnetic field strengths. Strong incentives exist to do so, as increasing the magnetic field strength increases the signal-to-noise ratio of images. However, ensuring patient safety becomes more challenging at high and ultrahigh field MRI (i.e., ≥3 T) compared to lower fields. The problem is exacerbated for patients with conductive implants, such as those with deep brain stimulation (DBS) devices, as excessive local heating can occur around implanted lead tips. Despit

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17

Kimmich, Rainer, Eberhard Rommel, and Peter Nickel. "NQR Imaging." Zeitschrift für Naturforschung A 47, no. 1-2 (1992): 361–66. http://dx.doi.org/10.1515/zna-1992-1-261.

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AbstractA rotating-frame NQR imaging (ᵨNQRI) procedure based on pure NQR is reported. The technique is suitable for powdery or crystalline solid materials containing quadrupole nuclei. The spatial information is encoded by gradients of the radio frequency amplitude of the excitation pulse. A special deconvolution procedure has been developed for the analysis of the spatial information encoded in the pseudo-FID of the NQR signal in the case of powder geometry. The technique is applicable to rotationally symmetric as well as to asymmetric electric field gradient tensors. The RF gradients are sui

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18

Li, Haiwang, Kaiyun Zhu, Tiantong Xu, Kaibo Lei, and Jingchao Xia. "Design and Manufacture of Millimeter-Scale 3D Transformers for RF-IC." Micromachines 13, no. 12 (2022): 2162. http://dx.doi.org/10.3390/mi13122162.

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The development of radio-frequency integrated circuits (RF-IC) necessitates higher requirements for the size of microtransformers. This paper describes millimeter-scale 3D transformers in millimeter-scale, solenoidal, and toroidal transformers manufactured using Micro-electromechanical Systems (MEMS). Two through-silicon via (TSV) copper coils with a high aspect ratio are precisely interleaved on a reserved air core (magnet core cavity) with a vertical height of over 1 mm because of the thickness of the substrate, which increases the performance while reducing the footprint. The effects of the

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19

Aebischer, H. A. "Comparative Study of the Accuracy of Analytical Inductance Formulae for Square Planar Spiral Inductors." Advanced Electromagnetics 7, no. 5 (2018): 37–48. http://dx.doi.org/10.7716/aem.v7i5.862.

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In the design of radio frequency (RF) microelectronic integrated circuits (IC’s) and of antennas for short-wave radio frequency identification (RFID) and telemetry systems, planar spiral coils are important components. Many approximate analytical formulae for calculating the inductance of such coils can be found in the literature. They can simplify the problem of designing inductors to a predefined inductance considerably. But the error statistics given by different authors cannot be compared because they are based on different or unknown domains of definition. Hence, it is not possible to dec

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20

Pashova, Katya, Elyes Dhaouadi, Ivaylo Hinkov, et al. "Graphene Synthesis by Inductively Heated Copper Foils: Reactor Design and Operation." Coatings 10, no. 4 (2020): 305. http://dx.doi.org/10.3390/coatings10040305.

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We report on the design of a reactor to grow graphene via inductively heating of copper foils by radio frequency (RF) magnetic fields. A nearly uniform magnetic field induced by Helmholtz-like coils penetrates the copper foil generating eddy currents. While the frequency of the current is being rapidly varied, the substrate temperature increases from room temperature to ~1050 °C in 60 s. This temperature is maintained under Ar/H2 flow to reduce the copper, and under Ar/H2/CH4 to nucleate and grow the graphene over the entire copper foil. After the power cut-off, the temperature decreases rapid

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21

Guo, Yi-Xin, Cong Lai, Zhi-Biao Shao, Kai-Liang Xu, and Ting Li. "Differential Structure of Inductive Proximity Sensor." Sensors 19, no. 9 (2019): 2210. http://dx.doi.org/10.3390/s19092210.

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The inductive proximity sensor (IPS) is applicable to displacement measurements in the aviation field due to its non-mechanical contact, safety, and durability. IPS can increase reliability of position detection and decrease maintenance cost of the system effectively in aircraft applications. Nevertheless, the specialty in the aviation field proposes many restrictions and requirements on the application of IPS, including the temperature drift effect of the resistance component of the IPS sensing coil. Moreover, reliability requirements of aircrafts restrict the use of computational-intensive a

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22

Kordzadeh, Atefeh, Dominik Holzmann, Alfred Binder, Thomas Moldaschl, Johannes Sturm, and Ali Roshanghias. "Miniaturized On-Chip NFC Antenna versus Screen-Printed Antenna for the Flexible Disposable Sensor Strips." IoT 1, no. 2 (2020): 309–19. http://dx.doi.org/10.3390/iot1020018.

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With the ongoing trend toward miniaturization via system-on-chip (SoC), both radio-frequency (RF) SoCs and on-chip multi-sensory systems are gaining significance. This paper compares the inductance of a miniaturized on-chip near field communication (NFC) antenna versus the conventional screen-printed on-substrate ones that have been used for the transfer of sensory data from a chip to a cell phone reader. Furthermore, the transferred power efficiency in a coupled NFC system is calculated for various chip coil geometries and the results are compared. The proposed NFC antenna was fabricated via

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23

Retico, Alessandra, Francesca Maggiorelli, Giulio Giovannetti, et al. "Double-Tuned Birdcage Radio Frequency Coil for 7 T MRI: Optimization, Construction and Workbench Validation." Electronics 12, no. 4 (2023): 901. http://dx.doi.org/10.3390/electronics12040901.

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The aim of the present study is the optimization, construction, and workbench validation of a double-tuned 1H- 23Na volume radio frequency (RF) coil suitable for human head imaging at 7 T, based on the birdcage geometry. The birdcage-like design which is considered is the four-ring model, in which two standard birdcage-like structures with the same diameters are nested along the longitudinal axis. Simulations based on Maxwell’s equations are performed to evaluate the RF magnetic field homogeneity and the RF coil efficiency varying the coil geometrical parameters. The RF magnetic field homogene

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24

Luo, Chao, Xiao Qing Hu, Chun Lai Li, et al. "Electromagnetic Simulation of Influence of Metamaterial for Magnetic Resonance Imaging at 3T." Materials Science Forum 848 (March 2016): 347–50. http://dx.doi.org/10.4028/www.scientific.net/msf.848.347.

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This paper presents an approach to investigate the influence of metamaterial to radio-frequency (RF) magnetic field in magnetic resonance imaging (MRI) at 3T. The variety of magnetic fields of RF receiving coil was calculated using the commercial electromagnetic simulation software (CST). The simulation results demonstrate that the transmitting and receiving magnetic field (B1+ and B1-) can be enhanced when the metamaterial is inserted into the RF coil, suggesting that the metamaterial has potential in MRI applications at 3T.

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25

Dou, Yan, Jinzhang Xu, Yuxia Hu, et al. "Optimization and Testing of a 1H/3He Double-Nuclear Quadrature Transmit Coil, Applying the Analytical Method at 0.06T." Journal of Medical Imaging and Health Informatics 10, no. 11 (2020): 2699–706. http://dx.doi.org/10.1166/jmihi.2020.3203.

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Application of polarized noble gas technology in lung functional magnetic resonance imaging (fMRI) has garnered attention for its unique advantages, such as high resolution and a lack of radiation exposure. This paper presents a 4-channel radio frequency (RF) coil design method for applications of an 1H/3He MRI system at the ultra-low field of 0.06T. For the complex model of the double-nuclear 1H/3He coil, the analytical optimization method (based on the theories of Biot-Savart law and PSO algorithm) and the electromagnetic (EM) field and radio frequency (RF) circuit co-simulation method was i

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26

Aebischer, Kathrin, Nino Wili, Zdeněk Tošner, and Matthias Ernst. "Using nutation-frequency-selective pulses to reduce radio-frequency field inhomogeneity in solid-state NMR." Magnetic Resonance 1, no. 2 (2020): 187–95. http://dx.doi.org/10.5194/mr-1-187-2020.

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Abstract. Radio-frequency (rf) field inhomogeneity is a common problem in NMR which leads to non-ideal rotations of spins in parts of the sample. Often, a physical volume restriction of the sample is used to reduce the effects of rf-field inhomogeneity, especially in solid-state NMR where spacers are inserted to reduce the sample volume to the centre of the coil. We show that band-selective pulses in the spin-lock frame can be used to apply B1-field selective inversions to spins that experience selected parts of the rf-field distribution. Any frequency band-selective pulse can be used for this

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27

Jiang, Wenjia, Liqiu Wei, Wenjie Fu, et al. "A newly designed ignition method for miniature radio frequency ion thruster." Review of Scientific Instruments 93, no. 3 (2022): 033506. http://dx.doi.org/10.1063/5.0071914.

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The ignition methods used by micro-radio frequency (RF) ion thrusters have a disadvantage, that is, the starting voltage and flow rate are obviously higher than the rated value, which will easily damage the grid after long-term use. To decrease the starting voltage and flow and reduce the damage to the grid, a new ignition system is proposed in this paper. This system uses an intake pipe as the ground electrode, has an inductance coil and a pre-ionization chamber, and enables the miniature RF ion thruster (Harbin Institute of Technology’s RF Ion Thruster 4, HRIT-4) to ignite at the rated volta

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28

Shigeta, Masaya, and Hideya Nishiyama. "Numerical Analysis of Metallic Nanoparticle Synthesis Using RF Inductively Coupled Plasma Flows." Journal of Heat Transfer 127, no. 11 (2005): 1222–30. http://dx.doi.org/10.1115/1.2039106.

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A thermal plasma flow is regarded as a multifunctional fluid with high energy density, high chemical reactivity, variable properties, and controllability by electromagnetic fields. Especially a radio frequency inductively coupled plasma (RF-ICP) flow has a large plasma volume, long chemical reaction time, and a high quenching rate. Besides, it is inherently clean because it is produced without internal electrodes. An RF-ICP flow is, therefore, considered to be very useful for nanoparticle synthesis. However, nanoparticle synthesis using an RF-ICP flow includes complicated phenomena with field

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29

Kumar, Suchit, Han-Jae Chung, You-Jin Jeong, Heung-Kyu Lee, and Chang-Hyun Oh. "Design and Implementation of Split-Leg Type Elliptical Whole-Body Birdcage RF Coil at 1.5 T MRI." Applied Sciences 11, no. 16 (2021): 7448. http://dx.doi.org/10.3390/app11167448.

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The feasibility and the development of a four-port elliptical birdcage radio frequency (RF) coil for generating a homogenous RF magnetic (B1) field is presented for a space-constrained narrow-bore magnetic resonance imaging (MRI) system. Optimization was performed for the elliptical birdcage RF coil by adjusting the position and the structure of the legs to maximize the B1+-field uniformity. Electromagnetic (EM) simulations based on RF coil circuit co-simulations were performed on a cylindrical uniform phantom and a three-dimensional human model to evaluate the B1+-field uniformity, the transm

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Shibata, T., K. Ohkoshi, K. Shinto, K. Nanmo, K. Ikegami, and H. Oguri. "Soundness evaluation of J-PARC RF ion source after 5-month continuous operation." Journal of Physics: Conference Series 2244, no. 1 (2022): 012041. http://dx.doi.org/10.1088/1742-6596/2244/1/012041.

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Abstract In the J-PARC user operation from Nov. 2020 – Apr. 2021, continuous operation of J-PARC Radio Frequency (RF) negative hydrogen ion (H-) source up to 3,651 hours (5 months) has been achieved. The ion source was operated with the output H- current of 60 mA, the duty factor (for plasma generation) 2% and the input RF power up to 30 kW. After the operation, phase space diagrams at the Radio Frequency Quadrupole linac (RFQ) entrance were measured by the emittance monitor at the ion source test stand (IS-TS) under the same operation condition as in the J-PARC Linac. Comparison of the phase

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Zhao, Yan, Xiaobin Yu, Wei Zhao, et al. "Inactivation of Endogenous Pectin Methylesterases by Radio Frequency Heating during the Fermentation of Fruit Wines." Fermentation 8, no. 6 (2022): 265. http://dx.doi.org/10.3390/fermentation8060265.

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Pectin methylesterase (PME) is a methyl ester group hydrolytic enzyme of either plant or microbial origin. Importantly, endogenous PMEs in fruits can catalyze the demethoxylation of pectin with a bulk release of methanol, largely impacting the fruit juice and wine industries. Here, we demonstrated radio frequency (RF) heating for inactivation of endogenous PMEs and investigated the relevant mechanisms underpinning enzymatic inactivation. The RF heating curve indicated that the optimal heating rate was achieved at an electrode gap of 90 mm (compared to 100 mm and 110 mm) and that the inactivati

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Zhao, Yan, Xiaobin Yu, Wei Zhao, et al. "Inactivation of Endogenous Pectin Methylesterases by Radio Frequency Heating during the Fermentation of Fruit Wines." Fermentation 8, no. 6 (2022): 265. http://dx.doi.org/10.3390/fermentation8060265.

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Pectin methylesterase (PME) is a methyl ester group hydrolytic enzyme of either plant or microbial origin. Importantly, endogenous PMEs in fruits can catalyze the demethoxylation of pectin with a bulk release of methanol, largely impacting the fruit juice and wine industries. Here, we demonstrated radio frequency (RF) heating for inactivation of endogenous PMEs and investigated the relevant mechanisms underpinning enzymatic inactivation. The RF heating curve indicated that the optimal heating rate was achieved at an electrode gap of 90 mm (compared to 100 mm and 110 mm) and that the inactivati

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33

Wang, Lei, Atsushi Sekimoto, Yuto Takehara, Yasunori Okano, Toru Ujihara, and Sadik Dost. "Optimal Control of SiC Crystal Growth in the RF-TSSG System Using Reinforcement Learning." Crystals 10, no. 9 (2020): 791. http://dx.doi.org/10.3390/cryst10090791.

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We have developed a reinforcement learning (RL) model to control the melt flow in the radio frequency (RF) top-seeded solution growth (TSSG) process for growing more uniform SiC crystals with a higher growth rate. In the study, the electromagnetic field (EM) strength is controlled by the RL model to weaken the influence of Marangoni convection. The RL model is trained through a two-dimensional (2D) numerical simulation of the TSSG process. As a result, the growth rate under the control of the RL model is improved significantly. The optimized RF-coil parameters based on the control strategy for

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Spataro, Simone, Nunzio Spina, and Egidio Ragonese. "Package-Scale Galvanic Isolators Based on Radio Frequency Coupling: Micro–Antenna Design." Electronics 11, no. 3 (2022): 291. http://dx.doi.org/10.3390/electronics11030291.

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This paper presents the design of on-chip micro-antennas for package-scale galvanic isolators based on RF planar coupling. A step-by-step design procedure is proposed, which aims at the maximization of the weak electromagnetic coupling between the RX and TX antennas integrated on side-by-side co-packaged chips to enable both high isolation rating and common-mode transient immunity thanks to the high dielectric strength and low capacitive parasitics of a molding compound-based galvanic barrier, respectively. Micro-antenna design guidelines are drawn, highlighting the main relationship between c

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Zhao, Y., and Z. F. Ding. "Comments on mechanisms for self-E → H and inverse H → E mode transitions in radio frequency inductively coupled plasmas." Physics of Plasmas 29, no. 8 (2022): 084503. http://dx.doi.org/10.1063/5.0107483.

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The previously observed self-E [Formula: see text] H and inverse [Formula: see text] mode transitions were explained by unrelated mechanisms. The argument in this Brief Communication finds that both mode transitions can be interpreted via wall-heating that affects electron density by changing neutral density. In the self-E [Formula: see text] H mode transition, the shift of the preset E-mode discharge to the E [Formula: see text] H mode-transition point is caused by the increasing neutral density in the cooling down process of the chamber wall overheated in the preceding high-power H-mode disc

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Garverick, Steven L., Michael Kane, Wen H. Ko, and Anthony J. Maniglia. "External Unit for a Semi-Implantable Middle Ear Hearing Device." Ear, Nose & Throat Journal 76, no. 6 (1997): 397–401. http://dx.doi.org/10.1177/014556139707600609.

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A miniaturized, low-power external unit has been developed for the clinical trials of a semi-implantable middle ear electromagnetic hearing device (SIMEHD) which uses radio-frequency telemetry to couple sound signals to the internal unit. The external unit is based on a commercial hearing aid which provides proven audio amplification and compression. Its receiver is replaced by an application-specific integrated circuit (ASIC) which: 1) adjusts the direct-current bias of the audio input according to its peak value; 2) converts the audio signal to a one-bit digital form using Σ—Δ modulation; 3)

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Bellakhal, N., K. Draou, and J. L. Brisset. "Nitriding of 304 Steel by a Nitrogen Plasma: Increasing Corrosion Resistance." Journal of Chemical Research 23, no. 1 (1999): 38–39. http://dx.doi.org/10.1177/174751989902300125.

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Exposure of a 304 stainless steel sample to an inductively coupled low pressure radio frequency (RF) nitrogen plasma leads to the formation of a nitriding layer. The protective properties of this layer are investigated by electrochemical methods. The corrosion potential of the steel in an aqueous solution depends on the working parameters of the plasma such as the time exposure and the distance between the steel sample and the high voltage (HV) coil of the treatment reactor.

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Kozlov, Mikhail, Marc Horner, Wolfgang Kainz, Nikolaus Weiskopf, and Harald E. Möller. "Modeling radio-frequency energy-induced heating due to the presence of transcranial electric stimulation setup at 3T." Magnetic Resonance Materials in Physics, Biology and Medicine 33, no. 6 (2020): 793–807. http://dx.doi.org/10.1007/s10334-020-00853-5.

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Abstract Purpose The purpose of the present study was to develop a numerical workflow for simulating temperature increase in a high-resolution human head and torso model positioned in a whole-body magnetic resonance imaging (MRI) radio-frequency (RF) coil in the presence of a transcranial electric stimulation (tES) setup. Methods A customized human head and torso model was developed from medical image data. Power deposition and temperature rise (ΔT) were evaluated with the model positioned in a whole-body birdcage RF coil in the presence of a tES setup. Multiphysics modeling at 3T (123.2 MHz)

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Beissner, Florian, Ulrike Nöth, and Thomas Schockert. "The Problem of Metal Needles in Acupuncture-fMRI Studies." Evidence-Based Complementary and Alternative Medicine 2011 (2011): 1–5. http://dx.doi.org/10.1155/2011/808203.

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Acupuncture is a therapy based on sensory stimulation of the human body by means of metal needles. The exact underlying mechanisms of acupuncture have not been clarified so far. Functional magnetic resonance imaging (fMRI) has become an important tool in acupuncture research. Standard acupuncture needles, which are made of ferromagnetic steel, however, are problematic in acupuncture-fMRI studies for several reasons, such as attraction by the scanner's magnetic field, significant image distortions and signal-dropouts, when positioned close to the head or even heating due to absorption of radio

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Li, Yiyuan, Jianhua Li, and Lixin Xu. "Method of Calculating the Inductance Value of MEMS Suspended Inductors with Silicon Substrates." Micromachines 9, no. 11 (2018): 604. http://dx.doi.org/10.3390/mi9110604.

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Microelectromechanical system (MEMS) suspended inductors have excellent radio-frequency (RF) performance. The inductance value is one of the main features that characterizes the performance of inductors. It is important to consider the influence of the substrate and the suspension height in calculating the inductance value accurately. In this paper, a method is proposed to calculate the inductance value of the MEMS suspended inductor wire with a silicon substrate, as the wire is the basic component of the inductor coil. Then the method is extended to the suspended inductors consisting of a sin

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Kanidi, Maria, Niki Loura, Anna Frengkou, Tatjana Kosanovic Milickovic, Aikaterini-Flora Trompeta, and Costas Charitidis. "Inductive Thermal Effect on Thermoplastic Nanocomposites with Magnetic Nanoparticles for Induced-Healing, Bonding and Debonding On-Demand Applications." Journal of Composites Science 7, no. 2 (2023): 74. http://dx.doi.org/10.3390/jcs7020074.

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In this study, the heating capacity of nanocomposite materials enhanced with magnetic nanoparticles was investigated through induction heating. Thermoplastic (TP) matrices of polypropylene (PP), thermoplastic polyurethane (TPU), polyamide (PA12), and polyetherketoneketone (PEKK) were compounded with 2.5–10 wt.% iron oxide-based magnetic nanoparticles (MNPs) using a twin-screw extrusion system. Disk-shape specimens were prepared by 3D printing and injection molding. The heating capacity was examined as a function of exposure time, frequency, and power using a radio frequency (RF) generator with

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Rushton, L. M., T. Pyragius, A. Meraki, L. Elson, and K. Jensen. "Unshielded portable optically pumped magnetometer for the remote detection of conductive objects using eddy current measurements." Review of Scientific Instruments 93, no. 12 (2022): 125103. http://dx.doi.org/10.1063/5.0102402.

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Electrically conductive objects can be detected using the principle of electromagnetic induction, where a primary oscillating magnetic field induces eddy currents in the object, which in turn produce a secondary magnetic field that can be measured with a magnetometer. We have developed a portable radio-frequency optically pumped magnetometer (RF OPM) working in unshielded conditions with sub-pT/[Formula: see text] magnetic field sensitivity when used for the detection of small oscillating magnetic fields, setting a new benchmark for the sensitivity of a portable RF OPM in unshielded conditions

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Serra, Ricardo, Mikhail L. Zheludkevich, Guido Grundmeier, and Mário G. S. Ferreira. "Modification of Organic Coatings with Thin Plasma Polymer Films. Influence on the Barrier Properties." Materials Science Forum 514-516 (May 2006): 1401–8. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1401.

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Deposition of thin plasma polymer films as final layer on organic coatings can provide one promising solution to tailor the surface properties offering third functionality and increased mechanical properties. The present work is dedicated to the study of the barrier properties of polyurethane coil coatings modified by different plasma polymerization processes. Microwave (MW) and radio frequency (RF) plasmas were used to deposit thin films with different composition from various precursor mixtures. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to reveal the

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Samila, Andrii, Oleksandra Hotra, Oleksandr Moisiuk, Mykola Khobzei, and Taras Kazemirskiy. "Modified Transceiver Antenna for NQR Detection of Explosive Objects in Demining Conditions." Energies 15, no. 19 (2022): 7348. http://dx.doi.org/10.3390/en15197348.

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This paper presents the conceptual stages of the simulation and development of a modified transceiver antenna for a high-power pulsed nuclear quadrupole resonance (NQR) detector of explosives containing the 14N isotope. At a frequency of 4.645 MHz, better characteristics are obtained using a nine-turn coil shaped as half of a Fermat spiral with an outer radius of 75 mm. Using a COMSOL Multiphysics numerical parametric simulation and a materials browser, it was possible to calculate a physical system with parameters as close to reality as possible. According to the results of the experimental s

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Xu, Lixin, Yiyuan Li, and Jianhua Li. "Analysis of the Failure and Performance Variation Mechanism of MEMS Suspended Inductors with Auxiliary Pillars under High-g Shock." Micromachines 11, no. 11 (2020): 957. http://dx.doi.org/10.3390/mi11110957.

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Microelectromechanical systems (MEMS) suspended inductors have excellent radio frequency (RF) performance and they are compatible with integrated circuit (IC). They will be shocked during manufacturing, transportation, and operation; in some applications, the shock amplitude can be as high as tens of thousands of gravitational acceleration (g, 9.8 m/s2). High-g shock will lead to the inductor deformation which affects its performance or even failure of the inductor structure. However, few studies have been carried out on the inductors under high-g shock. In this study, a kind of MEMS suspended

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Solis-Najera, S., F. Vazquez, R. Hernandez, O. Marrufo, and A. O. Rodriguez. "Numerical Analysis of a Flexible Dual Loop Coil and its Experimental Validation for pre-Clinical Magnetic Resonance Imaging of Rodents at 7 T." Measurement Science Review 16, no. 6 (2016): 294–99. http://dx.doi.org/10.1515/msr-2016-0037.

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Abstract A surface radio frequency coil was developed for small animal image acquisition in a pre-clinical magnetic resonance imaging system at 7 T. A flexible coil composed of two circular loops was developed to closely cover the object to be imaged. Electromagnetic numerical simulations were performed to evaluate its performance before the coil construction. An analytical expression of the mutual inductance for the two circular loops as a function of the separation between them was derived and used to validate the simulations. The RF coil is composed of two circular loops with a 5 cm externa

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Chen, Q. S., H. Zhang, V. Prasad, C. M. Balkas, and N. K. Yushin. "Modeling of Heat Transfer and Kinetics of Physical Vapor Transport Growth of Silicon Carbide Crystals." Journal of Heat Transfer 123, no. 6 (2001): 1098–109. http://dx.doi.org/10.1115/1.1409263.

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Wide-bandgap silicon carbide (SiC) substrates are needed for fabrication of electronic and optoelectronic devices and circuits that can function under high-temperature, high-power, high-frequency conditions. The bulk growth of SiC single crystal by physical vapor transport (PVT), modified Lely method involves sublimation of a SiC powder charge, mass transfer through an inert gas environment, and condensation on a seed. Temperature distribution in the growth system and growth rate profile on the crystal surface are critical to the quality and size of the grown SiC single crystal. Modeling of Si

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Hafh Marza, Hawraa, and Thamir H. Khalaf. "The Effect of Power on Inductively Coupled Plasma Parameters." Iraqi Journal of Physics 20, no. 3 (2022): 98–108. http://dx.doi.org/10.30723/ijp.v20i3.1017.

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In this work, we studied the effect of power variation on inductively coupled plasma parameters using numerical simulation. Different values were used for input power (750 W-1500 W), gas temperature 300K, gas pressure (0.02torr), 5 tourns of the copper coil and the plasma was produced at radio frequency (RF) 13.56 MHZ on the coil above the quartz chamber. For the previous purpose, a computer simulation in two dimensions axisymmetric, based on finite element method, was implemented for argon plasma. Based on the results we were able to obtain plasma with a higher density, which was represen

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Yu, Nan, Renaud Jourdain, Mustapha Gourma, Fangda Xu, Adam Bennett, and Fengzhou Fang. "Power Dissipation of an Inductively Coupled Plasma Torch under E Mode Dominated Regime." Micromachines 12, no. 7 (2021): 834. http://dx.doi.org/10.3390/mi12070834.

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This paper focuses on the power dissipation of a plasma torch used for an optical surface fabrication process. The process utilizes an inductively coupled plasma (ICP) torch that is equipped with a De-Laval nozzle for the delivery of a highly collimated plasma jet. The plasma torch makes use of a self-igniting coil and an intermediate co-axial tube made of alumina. The torch has a distinctive thermal and electrical response compared to regular ICP torches. In this study, the results of the power dissipation investigation reveal the true efficiency of the torch and discern its electrical respon

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Park, Jun Hyub, Yun Jae Kim, and Sung Hoon Choa. "Mechanical Properties of Al-3%Ti Thin Film for Reliability Analysis of RF MEMS Switch." Key Engineering Materials 306-308 (March 2006): 1319–24. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.1319.

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This paper presents a novel experimental method to investigate the strength of material, Al-3%Ti, which is commonly used in RF(radio frequency) microelectromechanical systems(MEMS) switch. The experimental method involves the development of a new tensile loading system. The new tensile loading system has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. A voice coil of audio speaker is used as the actuator of the loading system. And new specimen was designed

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