• Textile Coloration and Finishing
• /
• v.13 no.5
• /
• pp.306-311
• /
• 2001

Natural colorants haute attracted much attention all over the world because of their non-hazardous nature. The world is becoming increasingly aware of environmental Issues, such as ozone layer depletion, water pollution and waste disposal problems. The use of synthetic dyestuffs for their synthesis and application in the dyeing industries has been criticized due to introduction of contaminants into the environment. This has led to the desire to turn to the traditional, and more natural way of life. In this study, the colorants of extract of Ginkgo biloba bark were analysed and their dyeing properties on silk, wool and cotton were studied. It was found that uv-visible absorption spectra of extract of Ginkgo biloba bark showed two strong absorption Peaks in the range of 240 ∼400 In. From the result of IR spectra, the major ingredient of extract of Gikgo biloba bark seems to be the flavon which is one of the flavonoid derivatives. Silk, wool, and cotton dyed with the extract of Ginkgo biloba bark showed a reddish yellow color. Their color differences were increased drastically with repetition of dyeing by three times.

• Bulletin of the Korean Chemical Society
• /
• v.13 no.1
• /
• pp.17-20
• /
• 1992

Photoionization processes of TMPD in $H_2O$ and $D_2O$ were studied, by measuring steady-state absorption, emission, fluorescence excitation spectra, and fluorescence lifetimes on picosecond time scale. The steady-state absorption spectra showed that there exists a cation-ion pair (Wurster's Blue) in $H_2O$ and in $D_2O$ in the electronic ground state. Temperature and excitation wavelength dependence were also studied and the results show that the photoionization reaction in water is an activated process and the fluorescence lifetime is independent of the vibrational excess energy in the uv excitation range of 283-310 nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.352-353
• /
• 2007

The spectrum for $0_{\circ}$, $90_{\circ}$-polarized light coincides with the spectrum for non-polarized light and also with the spectrum was observed in the LB film deposited using a fresh solution. And, the formation and dissociation of J-aggregates, anisotropic behavior was no longer observed in the heat treated merocyanine dyes LB films. But, in the optical absorption spectra of same LB films by UV irradiation at room temperature, their were observed only dissociation of J-aggregates, that is decrease of absorbance peak without change spectral shape. On the other hand, in the case of optical absorption spectra of the LB films by the heat treatment at $70^{\circ}C$ in the air, both of the shifted absorption bands decay and a monomer absorption peak of about 530 nm appears instead.

• Korean Journal of Microbiology
• /
• v.10 no.3
• /
• pp.109-116
• /
• 1972

Three strains among 120 adenineless mutants of Brevibacterium ammoniagenes described in the previous paper were screened out to accumulate UV absorbing substances in the culture broth. It was analyzed to be 5'-inosinic acid and hypoxanthine by means of two dimensional paper chromatography, UV absorption spectra and periodate oxidation. 5'-IMP was isolated from the culture broth of the mutant No. 203 with anion-exchange resin amberite IRA-400 and recrystallized from ethanol. It was proved identical to authentic sample by Infra-red absorption spectrum. The growth responses of the mutant No. 2013 were demonstrated to require adenine, but not with adenosine and 5'-AMP.

• Analytical Science and Technology
• /
• v.13 no.3
• /
• pp.304-308
• /
• 2000

The iodide was recovered from a simulated spent fuel to the sodium bisulfite aqueous solution. It was discussed that the trace iodide (below 1 ppm) was determined without the matrix effect of 0.1 M sodium bisulfite and 1 mM $HNO_3$ in aqueous solution by ion chromatography with UV detection. AS4A-SC (DIONEX) column and UV-absorption spectrophotometer were used. The UV-absorption spectra of sodium bisulfite, nitric acid and iodide were obtained, and then 230 nm was selected as an absorption wavelength for iodide determination. 0.1 M NaCl eluent was optimum condition. In this condition the calibration curve of iodide was obtained on the range of about 0-1,000 ppb. The linear coefficient was 0.99993 and the detection limit was 5 ppb. The relative standard deviation was 1.26%.

• Journal of Information Display
• /
• v.5 no.4
• /
• pp.12-17
• /
• 2004

A series of statistical random copolymers of dioctylfluorene (DOF) and 3,4-ethylenedioxythiophene (EDOT) were synthesized by Ni (0) mediated polymerization and their light-emitting properties were compared with poly (9,9-di-n-octylfluorene) (PDOF). The synthesized polymers were characterized using UV-vis spectroscopy, TGA, photoluminescence (PL) & electroluminescence (EL) spectroscopy and by conducting molecular weight studies. The resulting polymers were found to be thermally stable and readily soluble in organic solvents. The UV-visible absorption and PL emission spectra of the copolymers were gradually red-shifted as the fraction of EDOT in copolymers increased. Light-emitting devices were fabricated in an ITO (indium-tin oxide)/PEDOT/polymer/Ca/Al configuration. Interestingly, the EL spectra of these devices were similar to the PL spectra of the corresponding polymer film. However, the EL devices constructed from the copolymer showed more than 10 times higher efficiency level than the devices constructed from the PDOF homopolymer. This higher efficiency is possibly the result of better charge carrier balance in the copolymer systems due to the lower HOMO levels of the copolymers in comparison to that of PDOF homopolymer.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.8
• /
• pp.2175-2179
• /
• 2010

Quantum mechanical properties of unsymmetrical and unfunctionalized trans-stilbene derivatives 1-3, which had been prepared by solid-phase parallel syntheses, were characterized using mPW1PW91/6-311G(d,p) (hybrid HF-DF) calculations. The total electronic energies, normal vibrational modes, Gibbs free energies, and HOMOs and LUMOs of sixteen different structures from three different groups were analyzed. The energy differences between the HOMOs and LUMOs of the various unsymmetrical trans-stilbenes are in accord with the maximum absorption peaks of the experimental UV spectra of 1-3. The calculated normal vibrational modes of 21 were comparable with its experimental IR spectrum. The $\pi$-conjugation in the para-connected biphenyl group of 2 is better than the one in the metaconnected biphenyl group on the shorter side of 3.

• Korean Journal of Food Science and Technology
• /
• v.22 no.4
• /
• pp.461-465
• /
• 1990

Fermented soybean sauce was fractionated by gel filteration chromatography and the physico-chemical properties of each fraction were investigated for the study on the separation and characteristics of antioxidative substances in the soybean sauce. The brown coloured melanoidin fractions(MF-I) collected by Sephadex G-10 column were found to contain nitrogeneous compounds and to have strong antioxidative activity and reducing power. The freeze dried MF-I was further fractionated with Sephadex G-50 and G-100 successively and then MF-II and MF-III fractions were observed to be the most effective antioxidant and reducing power among the fractions. The UV-VIS and IR absorption spectra of the each fraction were also determined and discussed.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.6
• /
• pp.889-894
• /
• 2004

Polyaddition reactions of 1,1-diethynyl-3-triethylsilyl-1-silacyclopent-3-ene with several organoborane derivatives have afforded the oligomeric materials containing organosilacyclic group and organoboron moiety along the oligomer main chains. All of these materials are soluble in THF as well as chloroform, and their molecular weights are in the range of 1,990/1,190-21,950/7,050 ($M_w/M_n$) with the polydispersity indexes of 1.67-3.43. The prepared oligomers are characterized by several spectroscopic methods such as $^1H,\;^{13}C, \;^{29}Si,\;^{11}B$ NMR and FTIR spectra along with elemental analysis. FTIR spectra of all the oligomers show that the new strong C=C stretching frequencies appear at 1599-1712 $cm^{-1}$, in particular. The UV-vis absorption spectra of the materials in THF solution exhibit the strong absorption bands at the ${\lambda}_{max}$ of 268-275 nm. The oligomeric materials show that the strong excitation peaks appear at the ${\lambda}_{max}$ of 255-279 nm and the strong fluorescence emission bands at the ${\lambda}_{max}$ of 306-370 nm. All the spectroscopic data suggest that the obtained materials contain both the organoboron ${\pi}$-conjugation moiety of C=C-B-C=C and the organosilacyclic group of 3-triethylsilyl-1-silacyclopent-3-ene along the oligomer main chains. The oligomers are thermally stable up to 162-200 $^{\circ}C$ under nitrogen.

• Elastomers and Composites
• /
• v.51 no.1
• /
• pp.1-9
• /
• 2016

Characterization of the UV oxidation for raw natural rubber (NR) was investigated in controlled conditions through image and FT-IR analysis. The UV oxidation was performed on a thin film of natural rubber coated on a KBr window at 254 nm and room temperature to exclude the thermal oxidation. Before or after exposure to UV light, image of the NR thin film was observed at a right or tilted angle. FT-IR absorption spectra were measured in transmission mode with the UV irradiation time. The UV oxidation of NR was examined by the changes of absorption peaks at 3425, 1717, 1084, 1477, 1377, and $833cm^{-1}$ which were assigned to hydroxyl group (-OH), carbonyl group (-C=O), carbon-oxygen bond (-C-O), methylene group $(-CH_2-)$, methyl group $(-CH_3)$, and cis-methine group $(cis-CCH_3=CH-)$, respectively. During the initial exposure period, the results indicated that the appearance of carbonyl group was directly related to the reduction of cis-methine group containing carbon-carbon double bond (-C=C-). Most of aldehydes or ketones from carbon-carbon double bonds were formed very fast by chain scission. A lot of long wide cracks with one orientation at regular intervals which resulted in consecutive chain scission were observed by image analysis. During all exposure periods, on the other hand, it was considered that the continuous increment of hydroxyl and carbonyl group was closely related to the decrement of methylene and methyl group in the allylic position. Therefore, two possible mechanisms for the UV oxidation of NR were suggested.