Owing to concerns regarding possible effects of extremely low frequency magnetic fields (ELF‐MF) on human health, many studies have been conducted to elucidate whether ELF‐MF can induce modifications in biological processes. Despite this, controversies regarding effects of ELF‐MF are still rife. In this study, we investigated biological effects of ELF‐MF on MCF10A, MCF7, Jurkat, and NIH3T3 cell lines. ELF‐MF with a magnetic flux density of 1 mT at 60 Hz was employed to stimulate cells for 4 or 16 h, after which the effects of ELF‐MF on cell proliferation, cell death, cell viability, and DNA synthesis rates were assessed. Whereas Jurkat and NIH3T3 cells showed no consistent variation in cell number, cell viability, and DNA synthesis rate, MCF10A and MCF7 cells showed consistent and significant decreases in cell number, cell viability, and DNA synthesis rates. However, there was no effect of ELF‐MF on cell death in any of tested cell lines. Next, to investigate the effect of ELF‐MF on gene expression, we exposed MCF7 cells to 2 mT at 60 Hz for 16 h and examined transcriptional responses by using gene expression array. We found a gene, PMAIP1, that exhibited statistically significant variation using two‐fold cut‐off criteria and certified its expression change by using semi‐quantitative and quantitative reverse transcription polymerase chain reaction. From these results, we concluded that ELF‐MF could induce the delay of cell cycle progression in MCF7 and MCF10A cells in a cell context‐specific manner and could up‐regulate PMAIP1 in MCF7 cells. Bioelectromagnetics. 36:506–516, 2015. © 2015 Wiley Periodicals, Inc.

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In this study, the computation analysis of the arc behavior in a 245 kV class 40 kA rated hybrid gas circuit breaker model has been performed. The model includes radiation transport, poly(tetrafluoroethylene) (PTFE) nozzle ablation, contact movement and turbulence-enhanced momentum and energy transport processes. It has been found that the ablated PTFE vapor from the nozzle in the breaker is mainly responsible for the high pressure buildup inside the thermal expansion chamber. This high pressure buildup helps in the strong blowing of the arc in the arcing chamber during the second current zero period.

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