Modeling and analysis of radial electromagnetic force and vibroacoustic behaviour in switched reluctance motors
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
Authors: Hu, Shenglong; Zuo, Shuguang; Liu, Mingtian; Wu, Hao; Liu, Zexu
Abstract
In this paper, the radial electromagnetic force and vibroacoustic behaviour of a switched reluctance motor (SRM) are predicted and analysed in detail. First, the radial force with the spatial-temporal distribution characteristics is derived analytically and verified by the 2D Fourier transform. Second, a multiphysics model, which not only includes the electromagnetic field, the mechanical field, and the acoustic field, but also takes into account the structural orthotropy and the non-uniformly distributed electromagnetic force, is established to predict the electromagnetic vibration and noise of a SRM. Third, based on the spatial and temporal orders of the force harmonics, the vibroacoustic mechanism of a SRM is revealed. Finally, the electromagnetic force and vibration under two control strategies, which include the angle position control (APC) and the current chopping control (CCC), are compared and analysed, respectively. The results show that the electromagnetic vibration and noise of a three-phase 12/8 SRM are mainly caused by the force harmonics with the spatial order of 4 and the temporal orders of 3 N-0 +/- 1 (N-0 = 0, 1, 2...). Besides, under the two control strategies, the orders of the electromagnetic force and vibration are the same, but the amplitudes are different. (C) 2020 Elsevier Ltd. All rights reserved.
ROS-Mediated Apoptotic Cell Death of Human Colon Cancer LoVo Cells by Milk delta-Valerobetaine
SCIENTIFIC REPORTS
Authors: D'Onofrio, Nunzia; Cacciola, Nunzio Antonio; Martino, Elisa; Borrelli, Francesca; Fiorino, Ferdinando; Lombardi, Assunta; Neglia, Gianluca; Balestrieri, Maria Luisa; Campanile, Giuseppe
Abstract
delta -Valerobetaine (delta VB) is a constitutive milk metabolite with antioxidant and anti-inflammatory activities. Here, we tested the antineoplastic properties of milk delta VB on human colorectal cancer cells. CCD 841 CoN (non-tumorigenic), HT-29 (p53 mutant adenocarcinoma) and LoVo (APC/RAS mutant adenocarcinoma) cells were exposed to 3kDa milk extract, delta VB (2mM) or milk+delta VB up to 72h. Results showed a time- and dose-dependent capability of delta VB to inhibit cancer cell viability, with higher potency in LoVo cells. Treatment with milk+delta VB arrested cell cycle in G2/M and SubG1 phases by upregulating p21, cyclin A, cyclin B1 and p53 protein expressions. Noteworthy, delta VB also increased necrosis (P<0.01) and when used in combination with milk it improved its activity on live cell reduction (P<0.05) and necrosis (P<0.05). VB-enriched milk activated caspase 3, caspase 9, Bax/Bcl-2 apoptotic pathway and reactive oxygen species (ROS) production, whereas no effects on ROS generation were observed in CCD 841 CoN cells. The altered redox homeostasis induced by milk+delta VB was accompanied by upregulation of sirtuin 6 (SIRT6). SIRT6 silencing by small interfering RNA blocked autophagy and apoptosis activated by milk+delta VB, unveiling the role of this sirtuin in the ROS-mediated apoptotic LoVo cell death.