• 생약학회지
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• 제15권2호
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• pp.108-113
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• 1984

The structure of tuguaconitine, MP $196{\sim}198^{\circ}C$, a new diterpene alkaloid isolated from the roots of Aconitum sibiricum P., was studied. Its empirical formula is $C_{23}H_{35}NO_7$ and spectroscopic evidence shows that the base contains three methoxyl, three hydroxyl and one N-ethyl groups. The acute toxicities of most of Aconitum species were strong and the acute toxicity of the alkaloid fraction of A. sibiricum was decreased by Glycyrrhizae, black bean or Zingiberis extract.

• Natural Product Sciences
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• 제14권2호
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• pp.131-137
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• 2008

From the 70% EtOH extract of the roots of Astragalus membranaceus (Leguminosae), eleven flavonoid derivatives and a lignan, were isolated and identified as liquiritigenin (1), daidzein (2), formononetin (3), sophorophenolone (4), calycosin (5), methylnissolin (6), isomucronulatol (7), isomucronulatol 7-O-glucoside (8), methylnissolin 3-O-glucoside (9), calycosin 7-O-glucoside (10), (+)-syringaresinol O-${\beta}$-D-glucoside (11), and isomucronulatol 7,2'-di-O-glucoside (12), by spectroscopic methods. This is the second report of the isoflavonoid derivatives sophorophenolone (4) and isomucronulatol 7,2'-di-O-glucoside (12) from a natural source, as well as the first report of compounds liquiritigenin (1), daidzein (2) and (+)-syringaresinol O-${\beta}$-D-glucoside (11) from the species A. membranaceus.

• Biomolecules & Therapeutics
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• 제18권2호
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• pp.191-196
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• 2010

In the course of screening for antioxidant compounds by measuring the radical scavenging effect on 1,1-diphenyl- 2-picrylhydrazyl (DPPH), a total extract of the twigs of Stewartia koreana (Theaceae) was found to show potent antioxidant activity. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of six phenolic compounds, ampelopsin (1), catechin (2), proanthocyanidin-A2 (3), fraxin (4), (2R, 3R)-taxifolin-3-${\beta}$-D-glucopyranoside (5), and (2S, 3S)-taxifolin-3-${\beta}$-D-glucopyranoside (6), as active principles. Their structures were elucidated by spectroscopic studies. Compounds 1-6 were isolated for the first time from this plant. Among them, three compounds 1-3 showed the significant antioxidative effects on DPPH, and riboflavin originated superoxide quenching activity. In riboflavin-nitrobluetetrazolium (NBT)-light system, compound 1 showed better superoxide quenching activity than vitamin C.

• 천문학회보
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• 제40권1호
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• pp.72.2-72.2
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• 2015

Wolf-Rayet galaxies, galaxies which show spectral features produced by Wolf-Rayet stars, are thought to be the place of recent massive star formation since the Wolf-Rayet phase covers relatively short timescale in the life of massive O and B type stars. Studying these galaxies provides a unique chance to understand how massive star formation occurs in a galaxy within a short timescale. In this work, we present the intermediate resolution optical spectra of 12 Wolf-Rayet galaxies obtained using longslit spectrograph on Bohyunsan Optical Astronomy Observatory. We derived the emission line ratios for a number of star-forming knots in each Wolf-Rayet galaxy. Star formation properties in these galaxies are discussed.

• Mycobiology
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• 제40권1호
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• pp.76-78
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• 2012

In an effort to identify the chemical constituents of fruiting bodies of $Fomitopsis$ $nigra$, a new lanostane triterpene glycoside, designated as fomitoside K, has been isolated from its methanolic extract. Its chemical structure was assigned on the basis of various spectroscopic studies.

• 천문학논총
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• 제27권4호
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• pp.171-175
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• 2012

Spectroscopic studies of extragalactic YSOs have shown a great progress in the last few years. Infrared observations with AKARI made significant contributions to that progress. In this proceeding, we are going to introduce our current research on the infrared observations of ices and dust around embedded YSOs in the Magellanic Clouds.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.78-78
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• 2012

In this presentation I will review the expanding thermal plasma chemical vapour deposition (ETP-CVD) technology, a deposition technology capable of reaching ultrahigh deposition rates. High rate deposition of a-Si:H, ${\mu}c$-Si:H, a-SiNx:H and silicon nanocrystals will be discussed and their various applications, mainly for photovoltaic applications demonstrated. An important aspect over the years has been the fundamental investigation of the growth mechanism of these films. The various in situ (plasma) and thin film diagnostics, such as Langmuir probes, retarding field analyzer, (appearance potential) mass spectrometry and cavity ring absorption spectroscopy, spectroscopic ellipsometry to name a few, which were successfully applied to measure radical and ion density, their temperature and kinetic energy and their reactivity with the growth surface. The insights gained in the growth mechanism provided routes to novel applications of the ETP-CVD technology, such as the ultrahigh high growth rate of silicon nanorystals and surface passivation of c-Si surfaces.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.3017-3024
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• 2012

The geometrical parameters, vibrational frequencies, and binding energies for $(H_2O_3)_n$ (n = 1-5) have been investigated using various quantum mechanical techniques. The possible structures of the clusters (n = 2-5) are fully optimized and the binding energies are predicted using energy differences at each optimized geometry. The harmonic vibrational frequencies are also determined and zero-point vibrational energies (ZPVEs) are considered for the better prediction of the binding energy. The best estimation of the binding energy for the dimer is 8.65 kcal/mol. For n = 2 and 3, linear structures with all trans forms of the HOOOH monomers are predicted to be the lowest conformations in energy, while the cyclic structures with all cis-HOOOH monomers are preferable structures for n = 4 and 5.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.993-996
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• 2012

We investigated fluorescence and fluorescence excitation of diphenylsilane (DPS) in a solution and molecular beams in combination with the aid of the DFT method. When the molecule was photoexcited at 250 nm in a cyclohexane solution, normal and excimer fluorescences were observed in the ranges of 260-320 and 330-450 nm, respectively. The fluorescence excitation spectrum indicates that the channel leading to the intramolecular excimer formation is not efficient in comparison with the normal fluorescence. Vibrationally resolved fluorescence excitation spectra were measured for the DPS molecules cooled in pulsed supersonic expansion of He in the range 262.2-271.7 nm, in which we can see several electronic excitation spectra exhibiting the electronic band origins. We found that the simulated absorption spectrum based on the time-dependent densityfunctional theory calculations accords well with the absorption spectrum.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.380.2-380.2
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• 2016

The emergence of new infectious diseases, the resurgence of several infections that appeared to have been controlled and the increase in bacterial resistance have created the necessity for studies directed towards the development of new antimicrobials. In the present study, we have synthesized a novel antioxidant ZnO nanoparticle that is newly designed and prepared by simple surface modification process. Antioxidative functionality is provided by the immobilization of antioxidant 3-(3,4-dihydroxyphenyl)-2-propenoic acid (caffeic acid, CA) onto the surface of ZnO nanoparticles. Microstructure and physical properties of the ZnO@CA nanoparticles were investigated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR) and steady state spectroscopic methods. Antimicrobial Activities of ZnO@CA nanoparticles were measured against various bacterial strains using antibacterial testing methods.