Journal of Physics D: Applied Physics

Lv, Yanpeng; Lu, Shihan; Wang, Yuqi; Liu, Xuan; Zhang, Jianhua

doi: 10.1088/1361-6463/addfe4pmid: N/A

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.

Zhao, Duo; Fang, Zhiheng; Tao, Shixing; Li, Shouxian; An, Jianzhu; He, Zhiyu; Wang, Xu; Xie, Zhiyong; Meng, Jianhua; Wang, Jing; Meng, Guangwei; Wang, Fang; Li, Qiong

doi:

Peng, Ximo; Jie, Yinxian; Wang, Shouxin; Yan, Huihui; Su, Can; Li, Xuan; Liu, Haiqing; Jiang, Jun; Tian, Yaoling; Liang, Qiyao

doi: 10.1088/1361-6463/ade163pmid: N/A

A solid-state source interferometer-polarimeter (SSIP) system has been designed and installed on the Experimental Advanced Superconducting Tokamak (EAST) for real-time electron density and Faraday rotation angle measurements. The SSIP system employs three novel terahertz solid-state sources, providing a probing beam at 0.654 THz. The intermediate frequency signals between each pair are 0.85 MHz, 1.275 MHz, and 2.125 MHz, with an output power of approximately 10 mW. High-sensitivity, low-phase-noise mixers are used in the SSIP system to acquire signals. A single-channel interferometer-polarimeter system has successfully measured both electron density and Faraday rotation angle data on the EAST device, providing real-time feedback for both density and Faraday rotation angle during EAST experiments. The resolution of density and Faraday rotation angle is 7.3×1016m−2 and 0.25°, respectively, which corresponds to the root mean square value of the noise. During the long-pulse, high-parameter steady-state operation of EAST, lasting several hundred seconds, the system demonstrated excellent robustness, and the experimental results showed good agreement with the POlarimeter-INTerferometer (POINT) system. Additionally, simulations of SSIP density and Faraday rotation angle were conducted using a ray-tracing program, and the results were consistent with experimental data. The measurement of the Faraday rotation angle measurements lays the foundation for the subsequent vertical three-channel SSIP measurement of horizontal displacement.

Zhang, Yuxuan; Kim, Minyoung; Oh, Yeongjun; Song, Han-Wook; Lee, Sunghwan

doi: 10.1088/1361-6463/added3pmid: N/A

Lithium-ion batteries (LIBs) have solidified their position as primary energy storage solutions for applications ranging from portable electronics to electric vehicles. As power-intensive applications expand, achieving fast charging/discharging performance is increasingly critical for high-energy-density batteries. However, the increased thickness of electrodes in LIBs presents significant challenges for charge (Li+ and electron) transfer kinetics, as longer charge migration distances hinder fast charging and discharging performance. Enormous efforts have been made to summarize advancements in materials chemistry—optimizing ionic pathways and crystal structure—to enhance Li+ transfer within the bulk of electrode materials. Yet, materials design and modifications fall short of fully addressing Li+ and electron transport limitations in thick electrodes. Despite the significance of potentially offering a solution to these constraints, the strategic engineering of electrode architecture has been rarely discussed. In this mini-review, we highlight recent innovations in electrode structural design for fast-charging applications, examining gradient architectures, low-tortuosity structures, and novel current collector designs. By exploring these advanced approaches and offering perspectives on future developments, we aim to promote further advancements toward achieving high-energy-density, fast-charging LIBs.

Rasheed, Bilal; Shabnam, Madeeha; Alqahtani, A

doi: 10.1088/1361-6463/ade1e6pmid: N/A

In this study, we examined the Goos–Hänchen (GH) shift of light beams reflected from the surfaces of various two-dimensional hexagonal materials. We employed a generalized Hamiltonian to analytically derive the band structures, longitudinal, and Hall conductivities of these materials. By manipulating the interaction between external electric fields and spin–orbit coupling, we demonstrated that topological phase transitions can be induced in buckled Xene monolayers (MLs), which can be probed through the GH shift. The GH shift exhibits distinct behaviors across different topological phases in these materials, providing valuable insights into their unique characteristics. Additionally, we investigated the valley- and spin-polarized spatial and angular GH shifts in ML transition-metal dichalcogenides upon reflection. We found that both lateral and angular shifts in these materials, as well as in buckled silicene MLs, are strongly influenced by spin and valley degrees of freedom. This sensitivity makes the GH shift a promising tool for advancing research in spintronics and valleytronics.

Jiang, Zaifu; Zuo, Jingning; Jin, Wenyuan; Pang, Jiafei; Miao, Junyi; Dai, Wei; Bi, Jie; Lu, Cheng

doi: 10.1088/1361-6463/ade0capmid: N/A

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.

Roy, S Le; Ndour, A; Guffond, R; Fernandez, J; Teyssèdre, G

doi: 10.1088/1361-6463/addfe3pmid: N/A

High voltage direct current links increasingly use polyethylene (PE) based materials as insulation, due to their outstanding electrical and thermal properties. However, it is known for long that ions, present in the crosslinked PE material, play a major role in the space charge behaviour, and hence in the ageing of the material. Crosslinking by-products seem to be related to the activity of ionic processes. However, it is a real challenge to identify the kind of ions and to determine its amount. In this context, simulation tools related to charge transport are of interest to apprehend the impact of the presence of ions, their transport and accumulation, on the overall macroscopic behaviour. The goal of the present paper is to propose a new model related to ion generation and transport, either accounting for dissociation of molecules or to their ionization. The simulations results, consisting in space charge density profiles and currents, are compared to experimental observations available in the literature to conclude on the possible mechanism of ion generation in PE materials containing by-products.

Koizumi, Hiroki; Yamasaki, Yuichi

doi: 10.1088/1361-6463/addfe2pmid: N/A

NiCo2O4 is a ferrimagnetic oxide with an inverse spinel structure that has garnered significant research interest due to its unique properties, including relatively high electrical conductivity, mixed-valence cations, and a Néel temperature exceeding room temperature. Furthermore, epitaxial NiCo2O4 thin films provide an exciting platform for tuning material properties and uncovering novel phenomena that are not observed in bulk single crystals. In this review, we highlight recent advancements in epitaxial NiCo2O4 thin films, focusing on: (i) the tunability of anti-site defects through controlled fabrication conditions, (ii) the emergence of easy-cone magnetic anisotropy (ECMA) induced by these anti-site defects, (iii) the realization of a nontrivial spin structure characterized by magnetic toroidal quadrupole order, driven by the ECMA, (iv) novel magneto-transport phenomena arising from this nontrivial spin structure, and (v) the correlation between this nontrivial spin structure and the concept of altermagnetism.

Pan, Tingyan; Chen, Haiyan; Tian, Jiawei; Yao, Xin; Liu, Qian; Chen, Fang; Xue, Zhichao; Zhou, Zili; Yin, Liangjun; Zhang, Linbo

doi: 10.1088/1361-6463/ade265pmid: N/A

In this paper, a dual-polarized wide-oblique-incidence-angle (DP-WOIA) wideband radar absorbing structure (RAS), composed of the geometric gradient dielectric loaded with asymmetric resistive sheets, is proposed. To achieve the DP-WOIA absorption performance, an anisotropic asymmetric impedance matching theory is presented, serving as a design guide for this structure. For comparison, the RAS with symmetric resistive sheets is also presented. Numerical and experimental results demonstrate that both transverse electric (TE) and transverse magnetic polarized waves exhibit excellent wave-absorption performance in the frequency range from 3.84 GHz to 18 GHz over an ultra-wide oblique incidence angle from 0° to 65°. Compared with the RAS loaded with symmetric resistive sheets, the anisotropic electromagnetic characteristics achieved by asymmetric resistive sheets mitigate the impedance mismatches for TE polarized waves under oblique incidence, resulting in the desired DP-WOIA wideband absorption effect. The underlying physical mechanisms of the RAS’s impedance-matching behavior are analyzed through anisotropic transmission line theory and equivalent impedance distributions. This proposed RAS is anticipated for use in wideband absorption applications with extremely oblique incidence.

Morse, Evan; Zhan, Wenbo

doi: 10.1088/1361-6463/ade0cbpmid: N/A

Hypoxia is considered a critical factor in the development of aneurysms, often associated with disturbed blood flow within dilated arteries. This study aims to explore the impact of such disturbed flow on transmural oxygen transport by modelling blood flow and oxygen dynamics within the lumen and across the multi-layered structure of the arterial wall. The findings reveal that wall shear stress, determined by disturbed blood flow, plays a crucial role in shaping oxygen distribution on the endothelium (END). Oxygen concentrations are generally lower in the dilated region, with distribution being highly heterogeneous. Significantly low oxygen values are found at the boundaries of the dilation and possibly at the midpoint. The predicted velocity of transmural interstitial fluid flow is located in the range from 0.01μms−1to 0.1μms−1. Oxygen primarily relies on diffusion to traverse the arterial wall layers, and its accumulation is affected by multiple factors. The average oxygen concentration in the inner layers of END, intima, and internal elastic lamina decreases as the length of the dilation increases, while a reduction in these concentrations with increasing dilation severity is observed only when the severity exceeds a critical threshold of 50%. In contrast, the average oxygen concentration in the middle layer of media (MED) increases as the aneurysm develops radially and axially, primarily due to a reduction in MED thickness. Moreover, increased blood flow velocity can effectively alleviate hypoxia across all layers of the arterial wall. The oxygen concentration at a single location does not adequately reflect the layer-wide oxygen distribution within the dilated arterial wall. These findings contribute to a deeper understanding of transmural oxygen transport mechanisms and offer insights into the progression of aneurysms.