• Journal of Applied Biological Chemistry
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• v.66
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• pp.266-271
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• 2023

The antioxidant capacity of the Psidium guajava leaf extracted with EtOH and their MeOH fractions using column chromatography were evaluated by 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging assays, total phenolic and flavonoid content, and Superoxide dismutase (SOD) assay. To determine its utility as a functional material, the crude extract was fractionated by flash column chromatography on ODS using a stepwise elution with combinations of MeOH/H₂O and then all the fractions were also investigated. In the results of antioxidant activities, the 40% and 60% MeOH fractions show the meaningful values, and then the two fractions were selected to examine the isolation and identification of the major constituents via HPLC and nuclear magnetic resonance. Further purification led to isolation of two quercetin derivatives; quercitrin (1) and isoquercetin (2). Through SOD assay, some methanol fractions via column chromatography and isolated compounds showed improved antioxidant activities compared to the extract.

• Clinical and Experimental Reproductive Medicine
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• v.33 no.3
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• pp.171-178
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• 2006

Objective: Human embryonic stem (ES) cells have a great potential in regenerative medicine and tissue engineering. The human ES cells could be differentiated into specific cell types by treatments of growth factors and alterations of gene expressions. However, the efficacy of guided differentiation and isolation of specific cells are still low. In this study, we characterized isolated cells from differentiated human ES cells by magnetic activated cell sorting (MACS) system using specific antibodies to cell surface markers. Methods: The undifferentiated hES cells (Miz-hESC4) were sub-cultured by mechanical isolation of colonies and embryoid bodies were spontaneously differentiated with DMEM containing 10% FBS for 2 weeks. The differentiated cells were isolated to positive and negative cells with MACS system using CD34, human epithelial antigen (HEA) and human fibroblast (HFB) antibodies, respectively. Observation of morphological changes and analysis of marker genes expression were performed during further culture of MACS isolated cells for 4 weeks. Results: Morphology of the CD34 positive cells was firstly round, and then it was changed to small polygonal shape after further culture. The HEA positive cells showed large polygonal, and the HFB positive spindle shape. In RT-PCR analysis of marker genes, the CD34 and HFB positive cells expressed endodermal and mesodermal genes, and HEA positive cells expressed ectodermal genes such as NESTIN and NF68KD. The marker genes expression pattern of CD34 positive cells changed during the extension of culture time. Conclusion: Our results showed the possibility of successful isolation of specific cells by MACS system from undirected differentiated human ES cells. Thus, MACS system and marker antibodies for specific cell types might be useful for guided differentiation and isolation of specific cells from human ES cells.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.292-297
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• 2005

Steam generator of a nuclear power plant has important rolls for the heat transfer and the isolation of radioactive materials. So bursting of the steam generator tube is directly related to the accident of nuclear power plants. Incone1600 has been used for the steam generator tube material. The material shows non-magnetic and metallic properties, eddy current NDT method has been employed for defects detection. In this work, a differential type of eddy current probe was developed to improve resolution of defect detection. To verify properties of the developed differential type eddy current probe, we have made reference material with SUS304 which has similar magnetic and electrical properties of Inconel600. Using the developed differential type eddy current probe, we can detect defect size of 0.25 mm in diameter and 0.2 mm in depth (volume of $1{\times}10^{-3}\;mm^3$) with the reference material.

• Journal of Applied Biological Chemistry
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• v.57 no.4
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• pp.295-299
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• 2014

The mulberry (Morus alba L.) root barks were extracted with 80% aqueous methanol at room temperature. The concentrated extract was partitioned as ethyl acetate (EtOAc), n-BuOH, and $H_2O$ fractions. From the EtOAc fraction, five triterpenoids were isolated through the repeated silica gel and octadecyl $SiO_2$ column chromatographies. According to the results of physico-chemical and spectroscopic data including nuclear magnetic resonance, mass spectrometry, and infrared, the chemical structures of the triterpenoids were respectively determined as ${\alpha}$-amyrin (1), ${\alpha}$-acetyl amyrin (2), lupeol (3), betulinic acid (4), and glutinol (5). Compounds 1, 3, and 5 were isolated for the first time from the mulberry root bark.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.428-433
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• 2003

In this study, we investigated the variation of microstructural and electromagnetic properties of YIG ferrites for Isolator/Circulator application with the sintering temperature and Zr addition. The composition of the ferrites was Y$_{2.1}$Ca$_{0.9}$Fe$_{4.4-x}$V$_{0.5}$In$_{0.05}$Al$_{0.05}$Zr$_{x}$O$_{12}$ with x=0, 0.05, 0.1 and 0.2. The YIG ferrites were prepared by the conventional ceramic sintering process. The Zr-substituted YIG ferrite, Y$_{2.1}$ Ca$_{0.9}$Fe$_{4.4-x}$V$_{0.5}$In$_{0.05}$Al$_{0.05}$ Zr$_{x}$O$_{12}$ showed the highest saturation magnetization (1097 gauss) at x=0.1. The microwave properties were shown as isolation of 18.60 dB and insertion loss of 0.45 dB at x=0.2. Additionally, Zr-substitution was effective in decreasing ferromagnetic resonance linewidth with Zr content.

• Journal of Applied Biological Chemistry
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• v.59 no.1
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• pp.5-7
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• 2016

One of oriental medicinal plants, Potentilla chinensis, has been used for anti-inflammation, hemostatic, decryption, and antipyretic. Especially, a root of Potentilla chinensis was used as important material for oriental medication. Although several kinds of bioactive component of Potentilla chinensis extract from stems and leaves were identified, the major component of Potentilla chinensis from roots is not well established. In this study, the root of Potentilla chinensis was extracted in different solvent system and analyzed by high performance liquid chromatography (HPLC). According to HPLC analysis, a major component was isolated and its physicochemical properties were evaluated by mass spectrometry and nuclear magnetic resonance. Based on these results, isolated compound was identified as 2,3,8-Tri-O-methylellagic acid. And quantification of 2,3,8-Tri-O-methylellagic acid with different extraction solvent system was performed for industrial application.

• Journal of Applied Biological Chemistry
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• v.59 no.4
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• pp.313-316
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• 2016

Sparassis crispa fruits were extracted in 80 % MeOH, and the concentrated extract was partitioned into EtOAc, n-butyl alcohol, and water fractions. The repeated octadecyl $SiO_2$ and silica gel ($SiO_2$) column chromatographies for the EtOAc and nbutyl alcohol fractions led to isolation of two ergosterol peroxides. There chemical structures were determined as ($3{\beta}$,$5{\alpha}$,$8{\alpha}$,22E)-5,8-Epidioxyergosta-6,22-dien-3-ol (ergosterol peroxide) (1) and 3-O-${\beta}$-D-glucopyranosyl ergosterol peroxide (2) based on spectroscopic data analyses including nuclear magnetic resonance, infrared spectrometry, and mass spectrometry (MS). Compounds 1 and 2 were for the first time isolated from S. crispa in this study.

• Journal of the Korean Magnetics Society
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• v.9 no.6
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• pp.312-320
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• 1999

Effect of deposition conditions on the magnetic properties of SmCo/Cr prepared by a RF magnetron sputtering method was studied. We obtained the maximum coercivity of 3.2 kOe in the sample of Cr(50 nm)/SmCo(40 nm, 50W, 20 mT)/Cr(150 nm, 100 W, 30 mT). The coercivity of the SmCo/Cr depends largely on the roughness of the Cr underlayer and the composition of SmCo. The roughness of the Cr underlayer increased with increasing the Ar pressure and thickness, and promoted the isolation of SmCo grains which resulted in an enhanced coercivity. The composition of the SmCo was changed with RF power and Ar pressure due to the mass difference between Sm and Co and the resputtering phenomena. The maximum coercivity was obtained in the composition of about 20 at.% Sm. The mechanism of magnetization reversal of the present SmCo films changed from domain wall motion to domain rotation as the RF power and the Ar pressure increase. This was though to be due to the defects, such as the roughness of Cr surface, porous column boundaries etc., which inhibit domain wall movement.

• Journal of the Korean Magnetic Resonance Society
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• v.23 no.4
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• pp.87-92
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• 2019

Allium hookeri (Liliaceae) has been received the increasing attention as a bioactive resource due to its potent biological activities including anti-oxidant, anti-obesity, anti-microbial and lipid-regulating activities. The beneficial effects of A. hookeri are known contributed from the high content of organosulfur compounds in A. hookeri. Though a variety of articles demonstrated that A. hookeri contains 'saponin' as a bioactive constituent, the scientific evidence to prove it was limited. In the present study, we have attempted to identify saponin contained in A. hookeri through chromatographic isolation and NMR spectroscopic methods. As a result, a spirostane-type steroidal saponin (1) has been successfully isolated from the methanolic extract of A. hookeri roots. The structure of 1 was elucidated by extensive 1D and 2D spectroscopic methods including ¹H-NMR, ¹³C-NMR, ¹H-¹H COSY, HSQC, HMBC and NOESY; identified as (3β, 22R, 25S)-spirost-5-en-3yl O-6-deoxy-α-L-mannopyranosyl-(1→4)-O-6-deoxy-α-L-mannopyranosyl-(1→4)-O-[6-deoxy-α-L-mannopyranosyl-(1→2)]-β-D-gluco pyranoside. 1 showed the significant inhibitory activity on mushroom tyrosinase with IC₅₀ values of 248.7 μM while the inhibition on alpha-glucosidase was not significant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2573-2584
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• 1997

In this paper, Ca, Sn substitute YIC(Yttrium Iron Garnet) ceramics were fabricated with Al substitutions in Fe sites. The strip-line circulator was designed and the properties of fabricated ciculator were measured. When the electric, magnetic and microwave properties were measured in Ca, Sn substituted YIG with Al subsititions, the relative permittivity and perfmeability in microwave frequencies were 15.623 and 0.972, repectively. For $Y_{2.4}Ca_{0.3}Sn_{0.3}Fe_{5-x}Al_xO_{12}$ garnet ceramics sintered at $1450^{\circ}C$, the ferrimagnetic resonance line width $\Delta{H}$) of 42 Oe and the saturation magnetization of 487 G were measured at 10 GHz. The strip-line circulator was simulated with 3-D FEM(Finite Element Method) software and designed to have insertion loss of 0.8dB, return loss of 25dB, isolation of 35dB at the center frequency of 1.9GHz. The fabricated strition loss of 0.8B, reture loss of 25dB, isolation of 35dB at the center frequency of 1.9GHz. The fabricated strip-line junction circulator using above YIG ceramics had insertion loss of 0.869dB, return loss of 26.955dB, isolation of 44.409dB at the center frequency of 1.9GHz.