• 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.23 no.1
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• pp.81-85
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• 2002

A new di-N-cyanoethylated 14-membered tetraaza macrocycle 1,8-bis(2-cyanoethyl)-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane $(L^2)$ and its nickel(II) complex $[NiL^2(OAc)]^+$ have been prepared. The square-planar complex $[NiL^2](C IO_4)_2$ can be prepared by addition of $HClO_4$ to a hot aqueous solution of $[NiL^2(OAc)]^+$ The Ni-N (tertiary amino group) bond distances $(2.008{\AA})$ of $[NiL^2](C IO_4)_2$ are relatively long, and the complex exhibits a d-d transition band at unusually long wavelength (ca. 515 nm). The complex $[NiL^2](C IO_4)_2$ rapidly reacts with acetate ion or ethylenediamine (en) to produce $[NiL^2(OAc)]^+$ or [Ni(en)_3]^{2+}$, respectively, and is readily decomposed in NaOH (0.01 M) solution. The chemical properties of $[NiL^2]^{2+}$ as well as its synthetic procedure are quite different from those for other related 14-membered tetraaza macrocyclic complexes. Effects of the N-cyanoethyl and C-methyl groups on the properties of $L^2$.

• Journal of environmental and Sanitary engineering
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• v.15 no.3
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• pp.75-87
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• 2000

This study was conducted to investigate the composition, detection rate, and exposure concentration of the airborne organic solvents from the working environmental measurements of total 4181 different type of workplace in 3280 workshops in which organic solvents are used. The results are as follows : 1. For all workplaces except washing, the detection rate of toluene and benzene were 80% and 20%, respectively. 2. The number of detection of aromatic hydrocarbon and ketone were ranged 1.41-2.39 and 0.62-0.90 per a sample in all workplaces except that showed 1.01 in washing. 3. The mean of detection frequency was $3.3{\pm}2.5$ in all workplaces and there was no significant difference among that of each workplaces. 4. The airborne concentrations of methyl methacrylate, ethyl alcohol, methyl alcohol, and ethyl ether were $43.5{\pm}47.0{\;}ppm,{\;}22.5{\pm}51.0{\;},{\;}19.8{\pm}57.6{\;}ppm,{\;}19.8{\pm}40.14{\;}ppm, respectively. And those of cellosolve, methyl cellosolve acetate, and N,N-dimethyl formamide were $4.1{\pm}4.5$ ppm, $4.0{\pm}18.5{\;}ppm$, and $5.6{\pm}7.7{\;}ppm$, respectively and exceeded the occupational exposure limits enforced by Ministry of Labor in Korea. As the above results, it is suggested that the components of organic solvents should be indentified to efficient management, of working environment and conducted the engineering control for the workplaces using the hazardous materials.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.383.3-384
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• 2002

Rosmarinic acid (1) and methyl rosmarinic acid (2), isolated from the ethyl acetate soluble fraction of the methanolic extract of Salvia miltiorrhiza Bunge (Lamiaceae) were found to be the tyrosinase inhibitors and scavengers of 1, 1-diphenyl-2-picrylhydrzyl (DPPH) radical. Compounds 1 and 2 inhibited the oxidation of L-tyrosine catalyzed by mushroom tyrosinase with $IC_{50}$/ of 16.8 $\mu\textrm{M}$ and 21.5 $\mu\textrm{M}$. respectively. It compared well with kojic acid. a well-known tyrosinase inhibitor. with an $IC_{50}$ of 22.4 $\mu\textrm{M}$. The inhibitory kinetics, analyzed by a Lineweaver-Burk plot, found rosmarinic acid and its methyl ester to be competitive inhibitors with $K_{i}$ of $2.35{\times}10^{-5}M$ and $1.52{\times}10^{-5}M$ respectively. In addition, compounds 1 and 2 showed the scavenging activities on DPPH radical, with $IC_{50}$ of 4.27 $\mu\textrm{M}$ and 3.05 $\mu\textrm{M}$. respectively. These scavenging effects were more potent than that of L-ascorbic acid ($IC_{50}$ = 11.75$\mu\textrm{M}$).

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.115-123
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• 1998

The semi-volatile fraction of cigarette mainstream smoke contains the most important aroma and taste that enhance smoke flavor. The components in mainstream smoke were analysed for commercially available cigarettes. To compare the semi-volatile components delivered from mainstream smoke of domestic cigarette with imported cigarette, we analyzed three types of filter cigarettes such as cellulose acetate mono filter, carbon dual filter and slim filter cigarette. Mainstream smoke was collected with a combination of Cambridge filter pad and liquid trap containing a small amount of acetone cooled by dry ice-methanol. We have identified 43 components from mainstream smoke by GC and GC/MS and found that benzene, toluene, 4-hydroxy-4-methyl-2-pentanone, 5-methyl-2-furaldehyde, acetic acids nicotine and triacetin were the main peaks in mainstream smoke. Also we have compared the relative amounts of semi-volatile compounds delivered from the domestic and imported cigarettes with three different filters. From the results of this study, the relative amounts of limonene, acetic acid, 5-methyl-Lfuraldehyde delivered from the imported cigarettes were generally higher than those of the domestic one's.

• Archives of Pharmacal Research
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• v.26 no.5
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• pp.367-374
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• 2003

In the course of screening neuraminidase inhibitors from herbal medicines, Reynoutria elliptica exhibited high inhibitory activity. Four active compounds were isolated from the ethyl acetate soluble fraction by consecutive purification using sillica gel, Sephadex LH-20 chromatography, and recrystallization. The chemical structures of these compounds were identified as 1,3,8-trihydroxy-6-methylanthraquinone (emodin) 1,8-dihydroxy-3-methoxy-6-methylanthraquinone (emodin 3-methyl ether; physcion), 1,3,8-trihydroxy-6-hydoxymethylanthraquinone ($\omega$-hydroxyemodin), and 3,5,4 -trihydroxystilbene (trans-resvertrol) by spectral data including MS, $^1 H-, and ^{13}C-NMR. The IC_{50}$ values of emodin, emodin 3-methyl ether, $\omega$-hydroxyemodin, and trans-resvertrol were 2.81, 74.07, 10.49, and 8.77 $\mu$M, respectively. They did not inhibit other glycosidase such as glucosidase, mannosidase, and galactosidase, indicating that they were relatively specific inhibitors of neuraminidase.

• Journal of Soil and Groundwater Environment
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• v.12 no.2
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• pp.27-36
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• 2007

A recent study showed that MTBE can be degraded by Fenton's Reagent (FR). The treatment of MTBE with FR, however, has a definite limitation of extremely low pH requirement (optimum pH $3{\sim}4$) that makes the process impracticable under neutral pH condition on which the ferrous ion precipitate forming salt with hydroxyl anion, which result in the diminishment of the Fenton reaction and incompatible with biological treatment. Consequently, this process using only FR is not suitable for in-situ remediation of MTBE. In order to overcome this limitation, modified Fenton process using NTA, oxalate, and acetate as chelating reagents was introduced into this study. Modified Fenton reaction, available at near neutral pH, has been researched for the purpose of obtaining high performance of oxidation efficiency with stabilized ferrous or ferric ion by chelating agent. In the MTBE degradation experiment with modified Fenton reaction, it was observed that this reaction was influenced by some factors such as concentrations of ferric ion, hydrogen peroxide, and each chelating agent and pH. Six potential chelators including oxalate, succinate, acetate, citrate, NTA, and EDTA were tested to identify an appropriate chelator. Among them, oxalate, acetate, and NTA were selected based on their remediation efficiency and biodegradability of each chelator. Using NTA, the best result was obtained, showing more than 99.9% of MTBE degradation after 30 min at pH 7; the initial concentration of hydrogen peroxide, NTA, and ferric ion were 1470 mM, 6 mM, and 2 mM, respectively. Under the same experimental condition, the removal of MTBE using oxalate and acetate were 91.3% and 75.8%, respectively. Optimum concentration of iron ion were 3 mM using oxalate which showed the greatest removal efficiency. In case of acetate, $[MTBE]_0$ decreased gradually when concentration of iron ion increased above 5 mM. In this research, it was showed that modified Fenton reaction is proper for in-situ remediation of MTBE with great efficiency and the application of chelatimg agents, such as NTA, was able to make the ferric ion stable even at near neutral pH. In consequence, the outcomes of this study clearly showed that the modified Fenton process successfully coped with the limitation of the low pH requirement. Furthermore, the introduction of low molecular weight organic acids makes the process more available since these compounds have distinguishable biodegradability and it may be able to use natural iron mineral as catalyst for in situ remediation, so as to produce hydroxyl radical without the additional injection of ferric ion.

• Advances in environmental research
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• v.7 no.2
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• pp.139-159
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• 2018

Green Leaf Volatiles (GLVs) is a class of biogenically emitted oxygenated hydrocarbons that have been identified as a potential source of Secondary Organic Aerosols (SOA) via aqueous oxidation. The physico-chemical properties of GLVs are vital to understanding their fate and transport in the atmosphere via fog processing, but few experimental data are available. We studied the aqueous solubility, 1-octanol/water partition coefficient, and Henry's law constant ($K_H$) of five GLVs at $25^{\circ}C$: methyl jasmonate, methyl salicylate, 2-methyl-3-buten-2-ol, cis-3-hexen-1-ol, and cis-3-hexenyl acetate. Henry's law constant was also measured at temperatures and ionic strengths typical of fog. Experimental values are compared to scarcely-available literature values, as well as estimations using group and bond contribution methods, property-specific correlations and molecular dynamics simulations. From these values, the partition coefficients to the air-water interface were also calculated. The large Henry's law constant of methyl jasmonate ($8091{\pm}1121M{\cdot}atm^{-1}$) made it the most significant GLV for aqueous phase photochemistry. The HENRYWIN program's bond contribution method from the Estimation Programs Interface Suite (EPI Suite) produced the best estimate of the Henry's constant for GLVs. Estimations of 1-octanol/water partition coefficient and solubility are best when correlating an experimental value of one to find the other. Finally, the scavenging efficiency was calculated for each GLV indicating aqueous phase processing will be most important for methyl jasmonate.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.214-219
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• 2006

A bacterial strain, initially identified as B1-3, was isolated from cheonggukjang, a traditional Korean dish made from fermented soybeans. Using the Biolog system and 16S rRNA sequence analysis, we identified B1-3 as Bacillus mojavensis. We manufactured a quickly fermented soybean (QFS) food product using the B. mojavensis, and guided by their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging ability. We isolated substances with antioxidative activity from it. Using mass spectrometry (MS) and nuclear magnetic resonance (NMR) techniques, we isolated 4 compounds from the ethyl acetate (EtOAc)-soluble neutral fraction of methyl alcohol (MeOH) extracts of the QFS food product (genistein, daidzein, 3R,4R-3-methyl-3,4-dihydroxy-2-pentanone, and 3S,4R-3-methyl-3,4-dihydroxy-2-pentanone) and 3 compounds from its acidic fraction (4-hydroxyphenylacetic acid, genistin, and daidzein). Two compounds from the neutral fraction (3R,4R-3-methyl-3,4-dihydroxy-2-pentanone and 3S,4R-3-methyl-3,4-dihydroxy-2-pentanone) were not detected in nonfermented soybeans (NFS) or in the filtrate of the LB broth used to culture B. mojavensis. However, they were detected in the filtrate of the same broth when it contained 2% glucose. These results suggest that these 2 compounds were derived from glucose (or other saccharides) in the soybean during fermentation. One compound that was found in the acidic fraction (4-hydroxyphenylacetic acid) was readily detected in NFS, but not in the culture broth. This suggests that 4-hydroxyphenylacetic acid was derived from NFS. We concluded that the antioxidative activity of cheonggukjang is a result of the interactions between soybean components and the microorganisms used in the fermentation of cheonggukjang.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.271-272
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• 2010