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Bo Shi Liu,김정은,이남호 대한화학회 2023 대한화학회지 Vol.67 No.2
In this study were evaluated the whitening and anti-oxidative activities from the extracts of Sorbus alnifolia branches, and identified the chemical structures of the active ingredients. In the whitening tests using α-MSH stimulated B16F10 melanoma cells, the 70% ethanol extract and n-butanol (n-BuOH) fractions concentration-dependently inhibited cellular melanogenesis and intracellular tyrosinase activities without causing cell toxicity. The total polyphenol content of n-BuOH and ethyl acetate (EtOAc) fractions were measured to be respectively 241.1 ± 1.1 and 222.9 ± 2.4 (mg/g GAE), and the total flavonoid con- tent of EtOAc fraction was 75.3 ± 2.0 (mg/g QE). Upon anti-oxidant studies with DPPH and ABTS+ radicals, potent radical scavenging activities were observed in the EtOAc and n-BuOH fractions. Moreover, in the study of cell protection efficacy using HaCaT keratinocytes damaged by H2O2, the EtOAc and n-BuOH fractions showed a very positive results on prevention of oxidative stress. Phytochemical studies for this extract resulted in the isolation of four compounds; 2-oxopomolic acid (1), euscaphic acid (2), epi-catechin (3), prunasin (4). These results suggested that the extract of S. alnifolia branches containing compounds 1-4 as natural ingredients could be used as whitening and anti-oxidant ingredients in cosmetic formulations.
Aloe-emodin suppresses prostate cancer by targeting the mTOR complex 2.
Liu, Kangdong,Park, Chanmi,Li, Shengqing,Lee, Ki Won,Liu, Haidan,He, Long,Soung, Nak Kyun,Ahn, Jong Seog,Bode, Ann M,Dong, Ziming,Kim, Bo Yeon,Dong, Zigang IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.7
<P>Phosphatidylinositol 3-kinase (PI3-K) amplification and phosphatase and tensin homolog (PTEN) deletion-caused Akt activation contribute to the development of prostate cancer. Mammalian target of rapamycin complex 2 (mTORC2) is a kinase complex comprised of mTOR, Rictor, mSin1, mLST8/G관L and PRR5 and functions in the phosphorylation of Akt at Ser473. Herein, we report that mTORC2 plays an important role in PC3 androgen refractory prostate cell proliferation and anchorage-independent growth. Aloe-emodin, a natural compound found in aloe, inhibited both proliferation and anchorage-independent growth of PC3 cells. Protein content analysis suggested that activation of the downstream substrates of mTORC2, Akt and PKC관, was inhibited by aloe-emodin treatment. Pull-down assay and in vitro kinase assay results indicated that aloe-emodin could bind with mTORC2 in cells and inhibit its kinase activity. Aloe-emodin also exhibited tumor suppression effects in vivo in an athymic nude mouse model. Collectively, our data suggest that mTORC2 plays an important role in prostate cancer development and aloe-emodin suppresses prostate cancer progression by targeting mTORC2.</P>
Study on the Formation Mechanism of Seismic Fracture Source of Debris Flow in Strong Seismic Area
( Liu Bo ),( Hu Xiewen ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2
The "5.12" Wenchuan Earthquake resulted in a large number of shattering of thin ridges. Induced by heavy rainfall, such high-level shattered mountains lose stability and damage, which will produce a large number of solid materials and significantly increase the hazards of debris flows in the earthquake area. In this paper, the formation mechanism of seismic crack source is studied by large-scale shaking table physical simulation test. Under different inclination of layers conditions, the acceleration, displacement, stress, deformation and failure characteristics of different parts of the model slope are simulated to analyze the seismic response law of thin ridges. The results show that: (1) the horizontal acceleration amplification coefficient of the model increases obviously when the height is above 3/5H from the bottom of the model, and the obvious vertical acceleration amplification effect appears at 3/4H from the bottom; (2) the acceleration response intensity of the hill body of the layered structure model is greater than that of the homogeneous structure model, and the correlation with the horizontal acceleration increases with the increase of the excitation frequency. (3) For the layered structure model, the larger the dip angle of the layer, the larger the top deformation is under the same excitation intensity; (4) For the weak interlayer model, the failure location of the horizontal interlayer model is higher than that of the inclined interlayer model, and the deformation of the thin interlayer model is larger than that of the thick interlayer model.
Liu, Bo,Tang, Chaojun,Chen, Jing,Xie, Ningyan,Tang, Huang,Zhu, Xiaoqin,Park, Gun-sik Springer US 2018 NANOSCALE RESEARCH LETTERS Vol.13 No.1
<P>It is well known that a suspended monolayer graphene has a weak light absorption efficiency of about 2.3% at normal incidence, which is disadvantageous to some applications in optoelectronic devices. In this work, we will numerically study multiband and broadband absorption enhancement of monolayer graphene over the whole visible spectrum, due to multiple magnetic dipole resonances in metamaterials. The unit cell of the metamaterials is composed of a graphene monolayer sandwiched between four Ag nanodisks with different diameters and a SiO<SUB>2</SUB> spacer on an Ag substrate. The near-field plasmon hybridizations between individual Ag nanodisks and the Ag substrate form four independent magnetic dipole modes, which result into multiband absorption enhancement of monolayer graphene at optical frequencies. When the resonance wavelengths of the magnetic dipole modes are tuned to approach one another by changing the diameters of the Ag nanodisks, a broadband absorption enhancement can be achieved. The position of the absorption band in monolayer graphene can be also controlled by varying the thickness of the SiO<SUB>2</SUB> spacer or the distance between the Ag nanodisks. Our designed graphene light absorber may find some potential applications in optoelectronic devices, such as photodetectors.</P>
Bo Liu,Ju-qin Shen,Zhao-jian Meng,Fu-hua Sun 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10
As the economy in China enters the new normal, Public-Private Partnerships have been an important measure for alleviating financial tensions and improving the administrative efficiency of the government. Based on the mode of open tendering for the selection of social capital partners for the new profit project, the open tendering procedures were analyzed. In addition, based on an improved TOPSIS model, the evaluation index system for the selection conducts a comprehensive evaluation of six aspects: reputation and performance, water pricing factor, financing program, construction program, operation and maintenance program, and transfer program.
Liu, Fang,Ma, Ni,Xia, Fang-Bo,Li, Peng,He, Chengwei,Wu, Zhenqiang,Wan, Jian-Bo The Korean Society of Ginseng 2019 Journal of Ginseng Research Vol.43 No.1
Background: Ginsenosides with less sugar moieties may exhibit the better adsorptive capacity and more pharmacological activities. Methods: An efficient method for the separation of four minor saponins, including gypenoside XVII, notoginsenoside Fe, ginsenoside Rd2, and notoginsenoside Fd, from Panax notoginseng leaves (PNL) was established using biotransformation, macroporous resins, and subsequent preparative high-performance liquid chromatography. Results: The dried PNL powder was immersed in the distilled water at $50^{\circ}C$ for 30 min for converting the major saponins, ginsenosides Rb1, Rc, Rb2, and Rb3, to minor saponins, gypenoside XVII, notoginsenoside Fe, ginsenoside Rd2, and notoginsenoside Fd, respectively, by the enzymes present in PNL. The adsorption characteristics of these minor saponins on five types of macroporous resins, D-101, DA-201, DM-301, X-5, and S-8, were evaluated and compared. Among them, D-101 was selected due to the best adsorption and desorption properties. Under the optimized conditions, the fraction containing the four target saponins was separated by D-101 resin. Subsequently, the target minor saponins were individually separated and purified by preparative high-performance liquid chromatography with a reversed-phase column. Conclusion: Our study provides a simple and efficient method for the preparation of these four minor saponins from PNL, which will be potential for industrial applications.