• 대한화학회지
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• 제43권5호
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• pp.535-539
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• 1999

Timmis반응을 이용하여 1,3-dimthyllumazine유도체를 합성하였다. 4-Amino-1,3-dimethyl-5-nitrosouracil(1)을 2,4-pentanedione, ethyl cyanoacetate, 그리고 ethyl acetoacetat와 반응시켜 6-acetyl-1,3,7-trimethyllumazine (2), ethyl 7-amino-1,3-dimethyllumazine-6-carboxylate (4), ethyl 1,3,7-trimethyl-lumazine-6-carboxylate (5)를 좋은 수율로써 합성하였다. 화합물 2,4,5의 6-아세틸 및 에스테르기에 대한 곁사슬 반응으로 다양한 1,3-dimethyllumazine 유도체들이 합성되었다. 합성된 화합물의 구조 및 물리적 특성은 NMR, UV, IR스펙트럼, 그리고 원소분석에 의하여 확인하였다.

• Macromolecular Research
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• 제14권5호
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• pp.545-551
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• 2006

Aqueous dispersions of pristine and functionalized (COOH- and $NH_2$-) multi-walled, carbon nanotubes (MWNTs) were prepared by using three types of surf act ants: sodium dodecyl sulfate (SDS, anionic), PEO-PPO-PEO (Pluronic P84, non-ionic), and poly(styrene/$\alpha-methyl$ styrene/acrylic acid) random terpolymer, i.e., alkali-soluble resin (ASR). The aggregate size, $\zeta-potential$, and storage stability of the MWNT aqueous dispersions were investigated by using dynamic light scattering and the turbidity method at room temperature. The exfoliation of the MWNT aggregates was determined by a UV-visible spectrophotometer and the morphology of the surfactant-coated MWNTs was observed by transmission electron microscopy (TEM). In all cases, ASR showed better dispersion stability with the smallest aggregate size, compared with the other surfactants, because of its unique molecular structure, i.e., randomly incorporated carboxylic acid groups and planar phenyl groups that can be irreversibly and effectively adsorbed on the MWNT surface. A predominantly-exfoliated morphology of MWNTs was observed in the presence of ASR from the strong intensity of the UV-vis spectrum at 263 nm.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2269-2279
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• 2009

Six metal-free organic dyes having thiophene (1), benzene-thiophene (2), thiophene-benzene (3), thiophene-pyridine (4), thiophene-thiophene (5), and pyridine (6) linkers between 9,9-dimethylfluorenyl terminal group and $\alpha$-cyanoacrylic acid anchor were synthesized. Among them, organic dye 5 showed the longest ${\lambda}_{max}$ value (424 nm) in UV-Vis absorption spectrum, better incident monochromatic photon-to-current conversion efficiency (IPCE), highest short circuit photocurrent density ($J_{SC},\;9.33\;mA^2/cm^2$), and highest overall conversion efficiency ($\eta$, 3.91%).

• 한국미생물·생명공학회지
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• 제21권1호
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• pp.59-65
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• 1993

방선균 분리주 GMT 1153로부터 ts/NRK 세포의 형태를 변형된 세포형태에서 정상세포의 형태로 전환하는 활성물질을 분리, 정제하였다. 활성물질 MT 1155는 UV, IR, 1H-NMR, 13C-NMR, mass,원소분석 등의 기기분석을 통하여 항진균성 항암물질인 toyocamycin으로 동정되었다. MT 1155는 ts/NRK 세포의 형태전환에 대한 활성외에도 PKA 효소활성 저해와 CTLL 세포에 대한 세포독성이 있으나 K562 소포형성 억제 및 PKC 효소활성에 대한 저해효과도 없었다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3755-3760
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• 2012

Single crystals of lithium potassium phthalate (LiKP) were successfully grown from aqueous solution by solvent evaporation technique. The grown crystals were characterized by single crystal X-ray diffraction. The lithium potassium phthalate $C_{16}\;H_{12}\;K\;Li_3\;O_{11}$ belongs to triclinic system with the following unit-cell dimensions at 298(2) K;$a=7.405(5){\AA}$;$b=9.878(5){\AA}$;$c=13.396(5){\AA}$;${\alpha}=71.778(5)^{\circ}$;${\beta}=87.300(5)^{\circ}$;${\gamma}=85.405(5)^{\circ}$; having a space group P1. Mass spectrometric analysis provides the molecular weight of the compound and possible ways of fragmentations occurs in the compound. Thermal stability of the crystal was also studied by both simultaneous TGA/DTA analyses. The UV-Vis-NIR spectrum shows a good transparency in the whole of Visible and as well as in the near IR range. Third order nonlinear optical studies have also been studied by Z-scan technique. Nonlinear absorption and nonlinear refractive index were found out and the third order bulk susceptibility of compound was also estimated. The results have been discussed in detail.

• 조명전기설비학회논문지
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• 제15권4호
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• pp.1-6
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• 2001

본 논문에서는 태양광 채광시스템의 출력광의 스펙트럼을 분석하였으며, 그 결과 태양광이 갖는 자외선 분포 보다 낮음을 알 수 있었다. 또한, 출력단의 조명환경을 조명설계 프로그램을 이용하여 6$\times$6$\times$2.3[m]인 최소작업 공간의 조명 환경을 예측하였으며, 광파이버 조명시스템의 출력단의 높이를 1.3[m]에 위치하였을 경우 50$\times$50[cm]의 면적에서 500[lx] 이상의 조도값을 얻을 수 있었다. 이와 같이, 시스템의 가격문제를 개선한다면 실내 조명광 원으로서 가능하리라 본다.

• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1877-1880
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• 2004

The simple and convenient determination of trace Hg(II) with its 2-mercaptobenzothiazole (MBT) complex in cetyltrimethylammonium bromide (CTAB) media has been studied. The UV-visible spectrum of Hg(II)-MBT complex in CTAB media had a good sensitivity and reproducibility. The Hg(II)-MBT complex in CTAB solution was very stable at pH 10.0 and could be quantitatively complexed if MBT were added to the sample solution more than 10 equivalent of Hg(II). The optimum concentration of CTAB was 0.001%. The calibration curve of Hg(II)-MBT complex with good linearity ($R^2$ = 0.9985) was obtained at the concentration range between $1.0{\times}10^-7$ and $1.0{\times}10^-5$ M in 0.001% CTAB media. The detection limit was $3.1{\times}10^-8$ M (6.2 ng m$L^{-1}$). Hg(II) in the synthetic samples and in the wastewater of the university's wastewater tank and the industrial wastewater tank could also be determined. Based on the experimental results, this proposed technique could be applied to the simple and convenient determination of trace Hg(II) in real samples.

• 천문학회보
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• 제37권2호
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• pp.71.1-71.1
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• 2012

We have identified local analogs of strong $H{\alpha}$ Emitters (HAEs) that dominate the z~4 Lyman-break galaxy population using the Sloan Digital Sky Survey (SDSS). At z<0.4, only 0.04% of galaxies are classified as HAEs with $H{\alpha}$ equivalent width larger than $500{\AA}$, comparable to that of z~4 HAEs. The $H{\alpha}$-to-UV luminosity ratio of local HAEs is consistent with that of z~4 HAEs, indicating relatively large specific star formation rate in these galaxies compared to traditionally studied UV-selected Lyman break analogs. Local HAEs are young, less evolved galaxies with low metallicity. It is still difficult to constrain whether the star formation in local HAEs is powered by minor mergers or by cosmological cold gas accretion. However, the stacked optical spectrum of local HAEs shows several strong ionization lines, for example HeII 4686 emission line, which are shown in Wolf-Rayet galaxies. Thus it is highly likely that local HAEs are galaxies with an elevated ionization parameter, either due to a high electron density or large escape fraction of hydrogen ionizing photons.

• Mycobiology
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• 제46권1호
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• pp.47-51
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• 2018

In the present study, the characterization and properties of silver nanoparticles from Yucca shilerifera leaf extract (AgNPs) were investigated using UV-visible spectroscopic techniques, zeta potential, and dynamic light scattering. The UV-visible spectroscopic analysis showed the absorbance peaked at 460 nm, which indicated the synthesis of silver nanoparticles. The experimental results showed silver nanoparticles had Z-average diameter of 729 nm with lower stability (195.1 mV). Additionally, our dates revealed that AgNPs showed broad spectrum antagonism ($p{\leq}.05$) against Fusarium solani (83.05%) and Macrophomina phaseolina (67.05%) when compared to the control after nine days of incubation. Finally, AgNPs from leaf extracts of Y. shilerifera may be used as an agent of biocontrol of microorganism of importance. However, further studies will be needed to fully understand the agronanotechnological potentialities of AgNPs from Yucca schidigera.

• 한국식품영양과학회지
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• 제21권2호
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• pp.136-142
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• 1992

냉동 건조한 귤(Citrus sinensis)의 껍질로 부터 methanol과 butanol추출물인 crude bioflavonoids를 건조중량으로 최초 시료대비 약 0.26%의 수율을 얻을수 있었다. 이 crude bioflavonoids를 gel filtration, HPLC를 이용하여 분리, 정제하였고 TLC, HPLC, UV spectrum, NMR spectral analysis를 통해 narirutin과 hesperidin으로 동정할 수 있었다. 또한 HPLC 정량분석 결과, narirutin과 hesperidin은 crude bioflavonoids의 g당 42mg과 530mg을 얻을 수 있었으며 귤 껍질의 주요 bioflavonoid는 hesperidin으로 판명되었다. 한편 실험 동물인 Sprague-Dawley종의 흰쥐를 대상으로 혈압 변화를 측정한 결과 귤 껍질의 주요 bioflavonoid성분인 hesperidin은 약물 투여 후 유의성있게 (p< 0.001) 혈압 저하효과가 있음을 관찰 할 수 있었다.