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1
Morphology Evolution of Mn5Si3 Phase and Effect of Mn content on Wear Resistance of Special Brass

Lifu Bie,Xiaohong Chen,Ping Liu,Tao Zhang,Xiangliu Xu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.4
- 복사/대출신청
There is a surge of interests in developing newer materials with special properties and many areas are being explored byseveral groups. We wish to report our findings on the effect of Mn content on the microstructure and tribological behaviorof special brass. With the increase of Mn content in the range of 4–10 wt%, the hardness and wear resistance of the specialbrass were all changed, and the adhesion with abrasion is form the friction behavior, mainly for all brasses. It was observedthat the matrix grain size was the smallest, and the hard phase was precipitated the most when the Mn quantity attained the8 wt% mark. During this period, the brass has the highest hardness and best wear resistance, which results from the grainrefinement and load transferring effect of precipitates. It was characterized by SEM, EDS, XRD, TEM, etc., and the resultsconfirmed that the precipitates were Mn5Si3and its structure was hollow hexagonal prism. The morphology evolution of thehard phase and its growth mechanism have been investigated, analyzed and simulated the nucleation and growth process ofthe Mn5Si3phase based on crystallography. The outcomes also showed that the presence of defects on the {0001} faces wasthe crucial factor for one-dimensional elongated structure of Mn5Si3phase.
2
An Empirical Study on the Utilization and Performance of the Korea-China FTA in Korean SMEs

Zhifeng Shen,Tae-In Kim,Lifu Chen 한국무역학회 2019 Journal of Korea trade Vol.23 No.4
- 원문보기 2
  ScienceON
  
  스콜라
Purpose - Based on the Korea-China FTA as the starting point, this paper makes an empirical analysis of the main influencing factors of the FTA utilization and performance of SMEs. Design/methodology - Taking into account the relationship between the internal and external environmental factors on FTA activities and performance of Korea’s SMEs, with PLS-SEM and data obtained by the questionnaire, Smart PLS was applied for the analysis. Findings - The recognition of FTA in SMEs has a significant positive effect on FTA utilization and performance, the international marketing orientation factor only has a significant positive effect on the performance, while the inadequate improvement of non-tariff barriers has a significant negative impact on FTA utilization. In addition, FTA activity has a significant mediation effect on two paths. Originality/value - This paper is of great practical relevance as a tool to enable SMEs to make effective utilization of Korea-China FTA and improve their imports and exports. The paper helps grasp the main factors affecting the utilization and performance of FTA for SMEs, also to establish FTA Business Model and FTA utilization plans for specific industries in the future regarding tariff and non-tariffs compatibility.
3
Two new triterpenoid saponins derived from the leaves of Panax ginseng and their antiinflammatory activity

Li, Fu,Cao, Yufeng,Luo, Yanyan,Liu, Tingwu,Yan, Guilong,Chen, Liang,Ji, Lilian,Wang, Lun,Chen, Bin,Yaseen, Aftab,Khan, Ashfaq A.,Zhang, Guolin,Jiang, Yunyao,Liu, Jianxun,Wang, Gongcheng,Wang, Ming-Kui The Korean Society of Ginseng 2019 Journal of Ginseng Research Vol.43 No.4
- 원문보기
Background: The leaves and roots of Panax ginseng are rich in ginsenosides. However, the chemical compositions of the leaves and roots of P. ginseng differ, resulting in different medicinal functions. In recent years, the aerial parts of members of the Panax genus have received great attention from natural product chemists as producers of bioactive ginsenosides. The aim of this study was the isolation and structural elucidation of novel, minor ginsenosides in the leaves of P. ginseng and evaluation of their antiinflammatory activity in vitro. Methods: Various chromatographic techniques were applied to obtain pure individual compounds, and their structures were determined by nuclear magnetic resonance and high-resolution mass spectrometry, as well as chemical methods. The antiinflammatory effect of the new compounds was evaluated on lipopolysaccharide-stimulated RAW 264.7 cells. Results and conclusions: Two novel, minor triterpenoid saponins, ginsenoside $LS_1$ (1) and 5,6-didehydroginsenoside $Rg_3$ (2), were isolated from the leaves of P. ginseng. The isolated compounds 1 and 2 were assayed for their inhibitory effect on nitric oxide production in LPS-stimulated RAW 264.7 cells, and Compound 2 showed a significant inhibitory effect with $IC_{50}$ of $37.38{\mu}M$ compared with that of NG-monomethyl-L-arginine ($IC_{50}=90.76{\mu}M$). Moreover, Compound 2 significantly decreased secretion of cytokines such as prostaglandin $E_2$ and tumor necrosis factor-${\alpha}$. In addition, Compound 2 significantly suppressed protein expression of inducible nitric oxide synthase and cyclooxygenase-2. These results suggested that Compound 2 could be used as a valuable candidate for medicinal use or functional food, and the mechanism is warranted for further exploration.