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Journal of Physics D: Applied Physics - latest papers

Latest articles for Journal of Physics D: Applied Physics

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  • A high-frequency AC generator with high gain powered by a 3.7 V battery for tumor treating fields
    High-frequency AC field (100–300 kHz), which could generate tumor treating fields (TTFields) has been FDA-approved for glioblastoma multiforme treatment. TTFields generator design with battery power is important for outdoor treatment. In general, the LCLC step-up resonant circuit is a viable filter option to improve the voltage of the AC waveform. In this study, we utilized the LCLC circuit with a linear isolated transformer to boost the voltage of the AC waveform with 200 kHz powered by batteries. Our theoretical analysis indicates that compared with the LCLC circuit, the resonant frequency changeis relatively narrow with a large range of excitation inductance of the transformer, thus benefiting from selecting the excitation inductance parameter to shift the targeted frequency to the resonant frequency, and then achieving a high voltage gain with low input power. The designed prototype can output a 66.0 V waveform at 200 kHz powered by a 3.7 V DC battery, where the voltage gain reaches 17.8. The excitation inductance of the transformer was properly selected to achieve a similar output voltage for capacitive bio-loading of the output waveform within 8.7 h with a low input power of 5.1 W and four 18650 lithium batteries (3200 mAh). The insulated electrode was designed for in vitro U251 cell proliferation experiments. The results showed that the cell viability could decrease to 70.2 ± 4.5%, compared with the control group, which indicates that the designed generator could inhibit cell proliferation significantly. This paper may provide a proper design method o AC generators for TTFields treatment.

  • Structural, electronic, and magnetic properties of MSi2N4 (M=Tm, Pa, Np) monolayers
    Recently, a new two-dimensional (2D) MoSi2N4 layered material was successfully synthesized [Science 369(2020)670], attracting significant attention from the research community. Following up on this work, we have successfully predicted other three stable MSi2N4 (M=Tm, Pa, Np) monolayers in the 2D MA2Z4 family using the CALYPSO structural prediction method combined with first-principles calculations. The energy band structure calculations show that the TmSi2N4 monolayer is a ferromagnetic (FM) semimetal, and the PaSi2N4 monolayer is a FM metal. In contrast, NpSi2N4 monolayer is a FM semiconductor with Curie temperature of 812 K, which is higher than those of the vast majority of 2D FM semiconductor materials. The Curie temperature of NpSi2N4 monolayer is attributed to the large magnetic moments of Np atoms and the strong exchange coupling interactions between the adjacent Np atoms. Interestingly, the Curie temperature of the NpSi2N4 monolayer can be further enhanced through reasonable modulation of biaxial strain. It is about 1008 K under a biaxial tensile strain of 3%. The present findings deepen our understanding of the structural and magnetic properties of MSi2N4 (M=Tm, Pa, Np) monolayers, and offer important insights for the design and synthesis of multifunctional nanoelectronic devices.

  • Design, fabrication, and characterization of Sc0.2Al0.8N-based film bulk acoustic resonator filter for S-band filter applications
    With the development of communication technology, the demand for high-speed transmission of massive data has imposed increasingly stringent performance requirements on filters. Film bulk acoustic resonators (FBARs) have been widely utilized in radio frequency (RF) filter applications due to their advantages such as high frequency and high quality factor (Q). In this study, we propose the design, fabrication, and characterization of Sc0.2Al0.8N-based film bulk resonators and RF filters. The proposed RF filters are designed for the S-band passband from 3.1 to 3.3 GHz, employing both Mason model circuit simulation and electromagnetic simulation. Through utilizing high-quality Sc0.2Al0.8N film, the measured effective electromechanical coupling coefficient ( ) of the FBAR reaches 10.64%. The measured −3 dB bandwidth of the filter is 223 MHz (spanning from 3.070 GHz to 3.293 GHz), with a low insertion loss of −2.058 dB and an out-of-band suppression of approximately −30 dB. This work demonstrates the potential of Sc0.2Al0.8N thin film bulk acoustic RF filters for S-band applications and provides valuable insights for future advancement in this field.

  • Geometry-intermediated transport in zeolite for advanced compact loudspeaker
    The linear enhancement of mechanical compliance through zeolite filling in compact loudspeakers has been theoretically and experimentally confirmed. However, utilization of this enhancement to elucidate the correlation between porous structure and acoustic properties remains elusive. This research optimizes gas diffusion ability in zeolite to enhance the acoustics performance of compact loudspeakers. Based on the mechanical compliance linear enhancement theory in zeolite-filled loudspeakers, an intrinsic parameter is introduced to measure adsorption site accessibility. By using a hydrothermal method and etching process, ZSM-5 with varying mesostructures, including normal stacking plates, b-oriented, and radial channel plate porous configurations, are successfully synthesized. The optimal (labeled by Z5-BR) sample combines the advantages of b-oriented and radial porous structures in favor of mass transfer. At 0.3 cm3 Z5-BR filling, the loudspeaker achieves 70 Hz resonance frequency shift Δf0, 1.05 mH·cm−3 mechanical compliance enhancement slope , and 35.79 mH·m−2 , leading to a maximum 3 dB sound pressure level increase at a sound frequency of 106 Hz. This study quantitatively links the refine microstructure of porous zeolite to acoustic behavior, offering a comprehensive framework for loudspeaker material estimation and igniting the fire to design the composition and structure of acoustic materials at hundreds of Hz through microscopic diffusion-adsorption processes.

  • Bio-inspired clover-shaped piezoelectric energy harvester with enhanced performance for low-speed wind energy harvesting
    Wind energy is abundant and contributes significantly to power systems, but the effective utilization of low-speed wind energy remains a challenge. Miniaturized wind energy harvesters based on the piezoelectric effect have been recognized as a promising solution for capturing low-speed wind energy. To enhance energy harvesting efficiency over a wide range of wind speeds, this study proposes an innovative bio-inspired clover-shaped piezoelectric energy harvester (BCPEH) modeled after the structure of clover leaves. By varying the relative width (RL) of each leaf of the clover-shaped bluff body, four different configurations were designed. To evaluate the output performance, the proposed BCPEH was tested in a wind tunnel. The findings reveal that the BCPEH with RL = 1.5 achieves a maximum output power of 2.08 mW, representing a 258.62% improvement compared to a conventional galloping piezoelectric energy harvester. Notably, the BCPEH with RL = 1.0 features a cut-in wind speed of only 1.6 m s−1. The development and shedding characteristics of vortices are revealed through computational fluid dynamic simulation. The semi-elliptic leaves of the clover-shaped bluff body significantly affect the vortex shedding mode and spacing at the microscopic level. This work provides valuable insights for designing high-performance, adaptable piezoelectric energy harvesters.