The purpose of this article is to review the current status of a frontier in dynamic spintronics and contemporary magnetism, in which much progress has been made in the past decade, based on the ...creation of a variety of micro and nanostructured devices that enable electrical detection of magnetization dynamics. The primary focus is on the physics of spin rectification effects, which are well suited for studying magnetization dynamics and spin transport in a variety of magnetic materials and spintronic devices. Intended to be intelligible to a broad audience, the paper begins with a pedagogical introduction, comparing the methods of electrical detection of charge and spin dynamics in semiconductors and magnetic materials respectively. After that it provides a comprehensive account of the theoretical study of both the angular dependence and line shape of electrically detected ferromagnetic resonance (FMR), which is summarized in a handbook format easy to be used for analysing experimental data. We then review and examine the similarity and differences of various spin rectification effects found in ferromagnetic films, magnetic bilayers and magnetic tunnel junctions, including a discussion of how to properly distinguish spin rectification from the spin pumping/inverse spin Hall effect generated voltage. After this we review the broad applications of rectification effects for studying spin waves, nonlinear dynamics, domain wall dynamics, spin current, and microwave imaging. We also discuss spin rectification in ferromagnetic semiconductors. The paper concludes with both historical and future perspectives, by summarizing and comparing three generations of FMR spectroscopy which have been developed for studying magnetization dynamics.
Cavity magnonics Zare Rameshti, Babak; Viola Kusminskiy, Silvia; Haigh, James A. ...
Physics reports,
09/2022, Letnik:
979
Journal Article
Recenzirano
Odprti dostop
Cavity magnonics deals with the interaction of magnons — elementary excitations in magnetic materials — and confined electromagnetic fields. We introduce the basic physics and review the experimental ...and theoretical progress of this young field that is gearing up for integration in future quantum technologies. Much of its appeal is derived from the strong magnon–photon coupling and the easily-reached nonlinear regime in microwave cavities. The interaction of magnons with light as detected by Brillouin light scattering is enhanced in magnetic optical resonators, which can be employed to cool and heat magnons. The microwave cavity photon-mediated coupling of a magnon mode to a superconducting qubit enables measurements in the single magnon limit.
Using electrical detection of a strongly coupled spin-photon system comprised of a microwave cavity mode and two magnetic samples, we demonstrate the long distance manipulation of spin currents. This ...distant control is not limited by the spin diffusion length, instead depending on the interplay between the local and global properties of the coupled system, enabling systematic spin current control over large distance scales (several centimeters in this work). This flexibility opens the door to improved spin current generation and manipulation for cavity spintronic devices.
Since the very beginning of RF and microwave integrated techniques and energy harvesting, Schottky diodes are most often used in mixing and rectifying circuits. However, in specific μW ...power-harvesting applications, the Schottky diode technique fails to provide a satisfactory RF-dc conversion efficiency mainly because of its high zero-bias junction resistance. This paper examines the state-of-the-art low-power microwave-to-dc energy conversion techniques. A comprehensive picture of the state-of-the-art on this aspect is given graphically, which compares different technologies such as transistor, diode, and CMOS schemes. Subsequent to the highlighted limitations of current devices, this work introduces, for the first time, a nonlinear component for low-power rectification based on a recent discovery in spintronics, namely, the spindiode. Along with an analysis of the role of nonlinearity and zero bias resistance in the rectification process of the spindiode, it is shown how the spindiode could enhance the rectification efficiency even at a very low-power level and how this technique would shift the design paradigms of diode-based devices and circuits.
For modular multilevel converters (MMCs) applied to medium-voltage dc distribution grids, using the traditional nearest level modulation (NLM) as in HVdc systems can lead to severe current distortion ...due to significantly reduced module numbers. This paper proposes a hybrid modulation method combining NLM and pulse width modulation (PWM) where only one module per arm operates under PWM mode. The proposed nearest level PWM (NL-PWM) method not only significantly reduces the current distortion, but also avoids the complicated voltage balancing control in each module. The harmonic characteristics of NL-PWM are derived using double Fourier transform, which provides a theoretical basis for selecting the module number and switching frequency for medium-voltage applications in accordance with grid harmonic requirements. Finally, the harmonic characteristics and feasibility of the proposed modulation method are validated by simulation and experimental studies on an MMC with six modules per arm. The simulated and experimental results reveal that NL-PWM has better voltage and current harmonic characteristics over NLM and CPS-PWM, thereby suiting the application of MMC with few models.
Cone-beam computed tomography (CBCT) is a crucial component of adaptive radiation therapy; however, it frequently encounters challenges such as artifacts and noise, significantly constraining its ...clinical utility. While CycleGAN is a widely employed method for CT image synthesis, it has notable limitations regarding the inadequate capture of global features. To tackle these challenges, we introduce a refined unsupervised learning model called improved vision transformer CycleGAN (IViT-CycleGAN). Firstly, we integrate a U-net framework that builds upon ViT. Next, we augment the feed-forward neural network by incorporating deep convolutional networks. Lastly, we enhance the stability of the model training process by introducing gradient penalty and integrating an additional loss term into the generator loss. The experiment demonstrates from multiple perspectives that our model-generated synthesizing CT(sCT) has significant advantages compared to other unsupervised learning models, thereby validating the clinical applicability and robustness of our model. In future clinical practice, our model has the potential to assist clinical practitioners in formulating precise radiotherapy plans.
Abstract
The determination of the optimal tax rate of water resources is one of the core as well as the key economic and technological issue in the ‘fee to tax’ work of water resources in China. ...Therefore, based on the introduction of the computable general equilibrium (CGE) model of water resources tax, using production parameters and consumption parameters of Hebei province in 2008–2017, the optimal tax rate of water resources is simulated and calculated, and the impact of the optimal tax rate on social welfare is analyzed. The results show that the reference of the best water resources tax rate in Hebei Province is 18%, and taxation on water resources effectively promotes the water use structure and water resources utilization efficiency in Hebei, which is beneficial to its water resources protection. The effective calculation of the optimal tax rate of water resources tax in Hebei Province proves the effectiveness of the CGE model in the formulation of water resources tax rate, which provides an important reference for the nationwide popularization of water resources ‘fee to tax reform’ in China and the formulation of water resources tax rate in other regions.
Oxidative stress and cardiomyocyte apoptosis play critical roles in doxorubicin (DOX)-induced cardiotoxicity. Previous studies indicated that fibronectin type III domain-containing 5 (FNDC5) and its ...cleaved form, irisin, could preserve mitochondrial function and attenuate oxidative damage as well as cell apoptosis, however, its role in DOX-induced cardiotoxicity remains unknown. Our present study aimed to investigate the role and underlying mechanism of FNDC5 on oxidative stress and cardiomyocyte apoptosis in DOX-induced cardiotoxicity. Cardiomyocyte-specific FNDC5 overexpression was achieved using an adeno-associated virus system, and then the mice were exposed to a single intraperitoneal injection of DOX (15 mg/kg) to generate DOX-induced cardiotoxicity. Herein, we found that FNDC5 expression was downregulated in DOX-treated murine hearts and cardiomyocytes. Fndc5 deficiency resulted in increased oxidative damage and apoptosis in H9C2 cells under basal conditions, imitating the phenotype of DOX-induced cardiomyopathy in vitro, conversely, FNDC5 overexpression or irisin treatment alleviated DOX-induced oxidative stress and cardiomyocyte apoptosis in vivo and in vitro. Mechanistically, we identified that FNDC5/Irisin activated AKT/mTOR signaling and decreased DOX-induced cardiomyocyte apoptosis, and moreover, we provided direct evidence that the anti-oxidant effect of FNDC5/Irisin was mediated by the AKT/GSK3β/FYN/Nrf2 axis in an mTOR-independent manner. And we also demonstrated that heat shock protein 20 was responsible for the activation of AKT caused by FNDC5/Irisin. In line with the data in acute model, we also found that FNDC5/Irisin exerted beneficial effects in chronic model of DOX-induced cardiotoxicity (5 mg/kg, i.p., once a week for three times, the total cumulative dose is 15 mg/kg) in mice. Based on these findings, we supposed that FNDC5/Irisin was a potential therapeutic agent against DOX-induced cardiotoxicity.
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