• Journal of the Korean Chemical Society
• /
• v.43 no.5
• /
• pp.535-539
• /
• 1999

1,3-Dimethyllumazine derivatives were synthesized by using Timmis reaction. The reaction of 4-amino-1,3-dimethyl-5-nitrosouracil(1) with 2,4-pentanedione, ethyl cyanoacetate, and ethyl acetoacetate provided 6-acetyl-1,3,7-trimethyllumazine (2), ethyl 7-amino-1,3-dimethyllumazine-6-carboxylate (4), and ethyl 1,3,7-trimethyllumazine-6-carboxylate (5) in good yieId, respectively. The various 1,3-dimethyllumazine derivatives were prepared from the side chain reactions of 6-acetyl and ester group in compound 2,4, and 5. The structure and physical properties of obtained compounds were characterized NMR, UV, IR spectrum, and elementary analysis.

• Macromolecular Research
• /
• v.14 no.5
• /
• pp.545-551
• /
• 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
• /
• v.30 no.10
• /
• pp.2269-2279
• /
• 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%).

• Microbiology and Biotechnology Letters
• /
• v.21 no.1
• /
• pp.59-65
• /
• 1993

We isolated Actinomycetes strain GMT 1155 and purified the active compound, MT 1155, on the morphological reversion of ts/NRK cell from the isolate. MT 1155 was identified as toyocamycin having antifungal and antitumor activities from physico-chemical properties and UV, IR, $^1H$-NMR, $^13C$-NMR and mass spectrum. MT 1155 showed the morphologically reversional activity on ts/NRK cell and the cytotoxicity on CTLL cell at the final concentrations of 1.7 JlM and 0.2 11M, respectively and its $IC_{50}$ value on protein kinase A enzyme was 2.3 $\mu$M. Also it had strong antifungal activity against several pathogenic fungi but not antibacterial activity. And it did not inhibit both protein kinase C activity and the bleb-formation of K562 cell induced by phorbol esters.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.11
• /
• pp.3755-3760
• /
• 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.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.15 no.4
• /
• pp.1-6
• /
• 2001

In this paper, it is analysed the spectrum of optical fiber output through the sunlight collector system. As the result of the analysis, the sunlight collector system's UV distribution is lower then the sunlight'UV distribution. Also, the lighting environments under the optical fiber bundles are predicted when applied to the minimum workroom's(6${\times}$6${\times}$2.3[m]) interior lighting by using a lighting design program. In case of optical filer output\`s hight of 1.3[m], the illuminance value over 500[lx] in the area 50${\times}$50[cm] was achieved. As the result its feasibility as an interior lighting source shows no serious problem except the system cost.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.12
• /
• pp.1877-1880
• /
• 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.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.71.1-71.1
• /
• 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
• /
• v.46 no.1
• /
• pp.47-51
• /
• 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.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.21 no.2
• /
• pp.136-142
• /
• 1992

The crude bioflavonoids were obtained by methanol and butanol extraction from Iyophilized orange (Citrus sinensis) peel. And then, its yield was about 0.26% in dry base. Two bioflavonoids were purified by gel filtration and HPLC, and could be identified narirutin and hesperidin through TLC, HPLC, UV spertrum and NMR analysis. The yields of narirutin and hesperidin from a gram of crude bioflavonoids were 42mg and 530mg respectively, and the main fraction of bioflavonoid from orange peel was supposed to be hesperidin. Each component was intravenously injected into Sprague-Dawley rats (1mg/100g body weight) and hesperidin was found to lower their blood pressure significantly (p < 0.001).