This paper proposes a new carrier-based PWM strategy for three-level inverter in transformerless photovoltaic systems. The proposed modulation method completely eliminates leakage currents by employing only medium vectors and one zero vector which produce the same common mode voltage. Due to carrier-based scheme, the proposed PWM method can allow overmodulation and be intuitively understood and simply implemented with analog or digital hardware. To show the feasibility of the proposed PWM method, the simulation results are presented.Index Terms-carrier-based PWM strategy, leakage current elimination, three-level inverter, transformerless photovoltaic system.
Electromagnetic fields (EMFs) are widely used in a number of cell therapies and bone disorder treatments, and nanomagnetic particles (NMPs) also promote cell activity. In this study, we investigated the synergistic effects of EMFs and NMPs on the osteogenesis of the human Saos‐2 osteoblast cell line and in a rat calvarial defect model. The Saos‐2 cells and critical‐size calvarial defects of the rats were exposed to EMF (1 mT, 45 Hz, 8 h/day) with or without Fe3O4 NMPs. Biocompatibility was evaluated with MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) and LDH (lactate dehydrogenase) assays. This analysis showed that NMP and EMF did not induce cell toxicity. Quantitative reverse‐transcription polymerase chain reaction indicated that the osteogenesis‐related markers were highly expressed in the NMP‐incorporated Saos‐2 cells after exposure to EMF. Also, the expression of gene‐encoding proteins involved in calcium channels was activated and the calcium concentration of the NMP‐incorporated + EMF‐exposed group was increased compared with the control group. In particular, in the NMP‐incorporated + EMF‐exposed group, all osteogenic proteins were more abundantly expressed than in the control group. This indicated that the NMP incorporation + EMF exposure induced a signaling pathway through activation of p‐ERK and calcium channels. Also, in vivo evaluation revealed that rat calvarial defects treated with EMFs and NMPs had good regeneration results with new bone formation and increased mineral density after 6 weeks. Altogether, these results suggest that NMP treatment or EMF exposure of Saos‐2 cells can increase osteogenic activity and NMP incorporation following EMF exposure which is synergistically efficient for osteogenesis.
The newly bred Picnic apple was extracted using water and ethanol for extracting solvent. Each water and ethanol extract showed relatively high phenolic compound of 3.69 and 5.55 mg/g. Each water and ethanol extract of Picnic apple showed 1,1-diphenyl-2-picrylhydrazyl of 88.10 and 88.07%, 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) of 98.79 and 97.25%, antioxidant protection factor of 2.07 and 2.00 PF and thiobarbituric acid reactive substances showed anti-oxidation effect of 9.69 and 19.83% all at 100 μg/mL phenolics concentration. Therefore extract of Picnic apple can be considered as anti-oxidant for antiaging. The anti-inflammatory effect (hyaluronidase inhibition) of extract of Picnic apple were 4.62% with water extract and 4.39% with ethanol extract both at 200 μg/mL phenolics concentration. Both water and ethanol extract showed low α-amylase inhibition effect but each showed 67.37 and 79.16% of α-glucosidase inhibition effect at 200 μg/mL phenolics concentration. In anti-wrinkle effect, water extract showed each 23.70 and 66.29% in elastase inhibition and collagenase inhibition and ethanol extract showed 64.83 and 65.70% each. These result show high potential for functional food and cosmetic source. Picnic apple was identified to have various functions of anti-oxidation, anti-inflammation, anti-wrinkle effect, and anti-diabetic effect. Therefore, Picnic apple is qualified as a source for new functional cosmetics and functional foods.
The study acknowledges the values of periodical indexing as information resources. The study identified periodicals users' needs of article indexing services based on focus group interviews. The study also conducted a comparative study of periodicals indexing services of libraries and databases in Korea and the US. The study argues for the need of seamless services for users of periodical articles indexing services. The study also recommends the elements needed for improving the current service, which includes establishing a collaborative indexing system, adopting a metadata standard, implementing authority files, incorporating social web services, offering diverse ways of information discovery based on facet approach, and stabilizing identification systems. •현 국내 정기간행물 기사색인 서비스 현 황은 어떠한가?
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