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1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin commonly used to produce an animal model of Parkinson's disease. Previous studies have suggested a critical role for neuronal nitric oxide (NO) synthase- (nNOS-) derived NO in the pathogenesis of MPTP. However, NO activity is difficult to assess in vivo due to its extremely short biological half-life, and so in vivo evidence of NO involvement in MPTP neurotoxicity remains scarce. In the present study, we utilized flow-sensitive alternating inversion recovery sequences, in vivo localized proton magnetic resonance spectroscopy, and diffusion-weighted imaging to, respectively, assess the hemodynamics, metabolism, and cytotoxicity induced by MPTP. The role of NO in MPTP toxicity was clarified further by administering a selective nNOS inhibitor, 7-nitroindazole (7-NI), intraperitoneally to some of the experimental animals prior to MPTP challenge. The transient increase in cerebral blood flow (CBF) in the cortex and striatum induced by systemic injection of MPTP was completely prevented by pretreatment with 7-NI. We provide the first in vivo evidence of increased nNOS activity in acute MPTP-induced neurotoxicity. Although the observed CBF change may be independent of the toxicogenesis of MPTP, this transient hyperperfusion state may serve as an early indicator of neuroinflammation.

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The magnetically coupled three-phase dual-active-bridge (DAB3) DC-DC converter is highly suitable for high-power applications. Although the converter has many advantages, the structure, working mode and electromagnetic effect of its key magnetic component-high-power medium-frequency three-phase transformer (MFT3) is more complex, and the capacity, frequency, loss, temperature rise and leakage inductance restrict each other, forming a complex and systematic design problem. This paper focuses on the overall design method and performance of high-power MFT3. Based on the analysis of steady-state voltage and current waveforms of DAB3 converter, the expression of harmonic current is derived by using fundamental wave analysis, and the analytical calculation method of copper loss is proposed. According to the piecewise linear flux density waveform excited by six-step voltage wave, the modified IGSE method is proposed to calculate the core loss. For MFT3 with three-phase five column core topology, a lumped parameter thermal network model with 14 temperature nodes is established to obtain the temperature rise. The influence of winding arrangement on leakage inductance is analyzed, and the analytical expression of leakage inductance is presented. On this basis, the design method of high-power MFT3 is proposed based on the free parameter scanning method. A 5 kHz, 15 kW MFT3 model with the nanocrystalline core material is made, and the leakage inductance, core loss, copper loss and temperature rise are extracted by finite element method (FEM) and experiment. The effectiveness of the proposed method is verified by comparing the design results with the FEM simulation and experimental results.

Purpose The purpose of this paper is to study the multi-objective optimization design method of high-power high-frequency magnetic-resonance air-core transformer (ACT). Design/methodology/approach First, this paper studies the interleaved winding technology, the process of modeling and simulation, the calculation method of high-frequency loss of Litz wire and the design of magnetic shielding in detail. Second, the multi-objective optimization design process of high-frequency magnetic-resonance ACT is established by parametric scanning method and orthogonal experiment method. Findings An ACT model of 2 kV/100 kW/81.34 kHz was designed. The efficiency, weight power density and volume power density are 99.61%, 21.6 kW/kg and 5.1 kW/kg, respectively. Finally, the multi-physical field coupling simulation method is used to calculate the port excitation voltages and currents and temperature field of ACT. The maximum temperature of the ACT is 95.5 °C, which meets the design requirements. Originality/value The above research provides guidance and basis for the optimization design of high-power high-frequency magnetic-resonance ACT.