• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.972-976
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• 1995

A trace amount of 4-biphenylcarboxylate having a pre-twisted biphenyl moiety was attached to a poly(methyl methacrylate) side chain and the fluorescence properties of the chromophore were investigated in various solvents such as ethyl acetate and butyl chloride. At room temperature, the polymer exhibited a distinct red shift of the short wavelength emission (325 nm) and an enhanced emission intensity around 430 nm upon excitation at the absorption red edge. The temperature dependence of the intensity ratio (R) of the 325 nm emission to the 430 nm emission was observed when exciting at the red edge over the temperature range between -20 and 60 ℃. However, the temperature dependence was not observed when exciting at the shorter wavelength. The Arrhenius plot of the R value shows the activation energy of 6.0 kJ/mol which is in good agreement with the energy required for the twist of the biphenyl moiety. Together with the results of red edge excitation effects it was concluded that the pre-twisted geometry of the biphenyl moiety is preserved by the restriction of the polymer chain to facilitate the formation of the twisted intramolecular charge transfer (TICT) state upon excitation.

• Bulletin of the Korean Chemical Society
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• v.16 no.6
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• pp.493-498
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• 1995

Ultrathin networks of itaconic acid copolymers and poly(allylamine) were produced by a Langmuir-Blodgett (LB) technique employing a double-chain amine as a monolayer template which was subsequently removed by extraction after thermal crosslinking. Itaconic acid copolymers used were copoly (itaconic acid-ethyl vinyl ether) and copoly (itaconic acid-n-butyl vinyl ether). The polyion-complexed monolayers of three components consisting of template amine, itaconic acid copolymer and poly (allylamine) were formed at the air-water interface. The Langmuir film properties have been studied by the surface pressure-area isotherm and fluorescence microscopy. The monolayers were transferred on solid substrates and were characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy (SEM). Two-dimensional polymer networks were formed through imide or amide linkages by heat treatment under vacuum. The heat-treated films were extracted with chloroform after immersion in aq. sodium chloride to remove the template amines. SEM observation of a LB film on a porous fluorocarbon membrane filter with pore diameter of 0.1 μm showed covering of the pores by six layers in the polyion complex state.

• Archives of Pharmacal Research
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• v.13 no.3
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• pp.257-260
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• 1990

Hantzch's type reaction of methyl acetopyruvate (2a), methyl 3-aminocrotonate (3) and 3-nitrobenzaldehyde (4) led to dimethyl 3-acetyl-6-methyl-4-(3'-nitrophenyl)-2, 5-dicarboxylate (5a) and methyl 2, 6-dimethyl-5-(1', 2'-dioxo-2'-methoxyethyl)-4-(3' nitrophenyl)- 2, 5-dicarboxylate (5a) and methyl 2, 6-dimethyl-5-(1', 2'-dioxo-2'methoxyethyl_4-(3' nitrophenyl)1, 4-dihydropyridine-3-carboxylate (6a) in 26.7 and 9.2% yield, respectively. On the other hand, methyl 2, 60dimethyl-4-(3'-nitrophenyl)-1, 4-dihydropyridine 3-carboxylate (9) was acylated by ethyl oxaly chloride to give methyl 2, 6-dimethyl-5-(1', 2'-dioxo-2'-ethoxyethyl)-4-(3'-nitrophenyl)-a, 4-dihydropyridine-3-carboxylate (6b) in 76.8% yield.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.198.1-198.1
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• 2003

As part of our systematic study for Korean Compositae plants, we have studied Saussurea nutans, collected at Gangwon Province on August 2001. Phytochemical studies on various species of genus Saussurea have resulted in the isolation sesquiterpene, triterpene and flavonoid$\^$1)/. S. nutans has been used for the treatment of rheumatic arthritis and dysmenorrhea in the Chinese folk medicine$\^$2)/. However, chemical constituents of this plant have not been reported until now. The MeOH extract of the aerial parts of this source was solvent fractionated into n-hexane, methylene chloride, ethyl acetate and BuOH soluble portions. (omitted)

• Journal of Life Science
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• v.22 no.4
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• pp.508-515
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• 2012

In this study, DEAE-cotton [derivatized by 2-(diethylamino)ethyl chloride hydrochloride (DEAE HCl)] was prepared as a carrier for immobilized $Pichia$ $stipitis$ for ethanol production. When cotton was derivatized with 0.5 M DEAE HCl, the yeast cell suspension was adsorbed at 100% of the initial cell $OD_{600}$. The adsorbed yeast cells were estimated to be 101.8 mg-dry cells/g-DEAE-cotton. In particular, when a flask culture using the immobilized yeast cells was conducted in a glucose and xylose-containing medium, the yeast cells on the DEAE-cotton gradually produced ethanol, according to glucose and xylose consumption; the ethanol yield was approximately 0.33 g-ethanol/g-monosaccharide. Because DEAE-cotton was successfully used as a carrier for ethanol production from a glucose and xylose-containing medium, we expect that this bioethanol production process may be used for the bioethanol production process from the hydrolysate of lignocellulosic biomass. All the results of DEAE-cotton were compared with those of DEAE-cellulose as a carrier for immobilization.

• Journal of Applied Biological Chemistry
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• v.55 no.3
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• pp.157-161
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• 2012

The aim of this research was to investigate the industrial application of Sedum sarmentosum. Antibacterial activities of the n-hexane, methylene chloride (MC), ethyl acetate, and n-butanol fractions of S. sarmentosum were tested against Escherichia coli, Staphylococcus aureus, and Helicobacter pylori. The MC fraction showed the strongest antibacterial activity against E. coli, with an inhibition zone greater than 13 mm in disc assays. At $100{\mu}g/mL$, all fractions scavenged more than 50% of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals (${\cdot}OH$). In particular, the MC fraction showed the strongest scavenging activity against DPPH and ${\cdot}OH$. In addition, we found that treatment with the MC fraction inhibited the growth of H. pylori and gastric adenocarcinoma cells. The present results suggest that the MC fraction of S. sarmentosum would play the promising protective role against pathogenic bacteria and free radicals.

• Korean Journal of Medicinal Crop Science
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• v.8 no.1
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• pp.1-8
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• 2000

Achillea sibirica Ledeb. is widely distributed in Korea and has been often used as folk medicine in peptic and tonic. As one of our searches for bioactive (anti oxidation) compounds from medicinal plants, we studied Achillea sibirica Ledeb. (Compositae). Antioxidant activity of Achillea sibirica was determined by measuring lipid peroxide produced when a mouse liver homogenate was exposed at $90^{\circ}C$ using 2-thiobarbituric acid (TBA) and by evaluation the radical scavenging activity on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. Whole parts of Achillea sibirica was extracted with methanol and its extracts was fractionated with organic solvent; n-Hexane, methylene chloride, ethyl acetate, n-Butanol. EtOAc fraction exhibited antioxidant activity and From its, two flavonoid glycosides were isolated by silica gel and gel filtration colume chromatography and identified to kampferol 3-O-glucoside and luteolin 7-O-neo-hesperidoside, respectively, by physico-chemical and spectroscopical method. At antioxidant activity test for two compounds isolated, antioxidant activity was showed too. And from hexane fraction sterol was is isolated and identificated to mixture of campesterol, stigmasterol, and ${\beta}-sitosterol$.

• The Korean Journal of Food And Nutrition
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• v.23 no.1
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• pp.118-123
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• 2010

To estimate the regulatory effects of Scutellaria baicalensis extracts on melanin biosynthesis, we evaluated the regulatory effects of the tyrosinase gene on B16 melanoma cells. The results revealed that methanolic extracts of Scutellaria baicalensis resulted in a high increase in the expression of the tyrosinase gene. Specifically, treatment with extracts at concentrations of $10\;{\mu}g/m{\ell}$ and $100\;{\mu}g/m{\ell}$ resulted in increases in tyrosinase gene expression rates of approximately 231% and 256%, respectively, when compared to the control. Moreover, the solvent fraction layers(methylene chloride, ethyl acetate, butyl alcohol, water) improved the expression of the tyrosinase gene, but to a lesser degree than the methanolic extracts. An MTT assay revealed, that the methanolic extract exhibited very low cytotoxicities at $10\;{\mu}g/m{\ell}$ and $100\;{\mu}g/m{\ell}$. Taken together, the results of this study indicated that the methanolic extracts of Scutellaria baicalensis was a very effective positive regulator of tyrosinase gene expression.

• Polymer(Korea)
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• v.36 no.2
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• pp.169-176
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• 2012

Based on our experience in developing resistive humidity sensor, interdigital gold electrodes with different fingers and gaps have been fabricated on a glass epoxy (GE) substrate using screen printing techniques. The basic structure of the electrode consisted of a 3-, 4- and 5-fingers with gaps of 310 and 460 ${\mu}m$. Gold electrode/GE was prepared by first printing silver nanopaste, followed by consecutive electroless plating of Cu, Ni and then Au. Copolymer of [2-(methacryloyloxy)ethyl] dimethyl benzyl ammonium chloride (MDBAC) and methyl methacrylate (MMA) was used as a humidity-sensing polyelectrolyte, which was fabricated by a screen printing method on the Au electrode/GE substrate. The flexible humidity sensor showed acceptable linearity between logarithmic impedance and relative humidity in the range of 20-95%RH, low hysteresis of 1.5%RH, good response and recovery time of 75 sec at 1 V, 1 kHz, and $25^{\circ}C$. Electrode construction had a significant influence on the humidity-sensing characteristics of polymeric humidity sensors. The activation energy between electrode and ion conducting polyelectrolyte plays an important role in explaining the differences of humidity sensing characteristics such as temperature dependence, sensitivity, linearity and hysteresis.

• Membrane Journal
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• v.33 no.2
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• pp.77-86
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• 2023

In this study, pore-filled ion exchange membranes with low membrane resistance and high hydroxide ion conductivity was developed. To improve alkali durability, a porous substrate made of polytetrafluoroethylene was used, and a copolymer was prepared using monomers 2-(dimethyl amino) ethyl methacrylate (DMAEMA) and vinyl benzyl chloride (VBC) for pores. divinyl benzene (DVB) was used as the cross-linker, and ion exchange membranes were prepared for each cross-linking agent content to study the effect of the cross-linker content on DMAEMA-DVB and VBC-DMAEMA-DVB copolymers. As a result, chemical stability is improved by using a PTFE material substrate, and productivity can be increased by enabling fast photo polymerization at a low temperature by using a low-pressure UV lamp. To confirm the physical and chemical stability of the ion exchange membrane required for an anion exchange membrane fuel cell, tensile strength, and alkali resistance tests were conducted. As a result, as the cross-linking degree increased, the tensile strength increased by approximately 40 MPa, and finally, through the silver conductivity and alkali resistance tests, it was confirmed that the alkaline stability increased as the cross-linking agent increased.