• Fisheries and Aquatic Sciences
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• v.18 no.3
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• pp.241-247
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• 2015

In an effort to discover alternative phytotherapeutic antimicrobial agents to combat Streptococcus parauberis, a fish pathogenic bacterium, we evaluated the antibacterial activity of seaweed extracts in vitro. A methanolic extract of Ecklonia cava exhibited strong antibacterial activity against S. parauberis isolated from olive flounder Paralichthys olivaceus. Furthermore, the n-hexane soluble (Hexane) fraction of the E. cava methanolic extract exhibited the greatest antibacterial effect on S. parauberis strains with a minimum inhibitory concentration (MIC) ranging from 256 to $1,024{\mu}g/mL$. In addition, the MIC values of oxytetracycline against antibiotic-resistant S. parauberis were markedly reduced up to 64-fold in combination with the Hexane fraction, suggesting that the antibacterial activity of the antibiotic was restored when combined with the Hexane fraction. The interaction between both antibiotics and the Hexane fraction was assessed by the fractional inhibitory concentration (FIC) index. The Hexane fraction and oxytetracycline combination against antibiotic-resistant S. parauberis strains resulted in a median ${\sum}FIC$ range of 0.502 to 0.516. Thus, the synergistic ranges of median ${\sum}FIC$ < 1 were observed for all combinations of the Hexane fraction and oxytetracycline against S. parauberis. To the best of our knowledge, this is the first report indicating the efficacy of an E. cava extract against fish pathogenic bacterium S. parauberis.

• Analytical Science and Technology
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• v.15 no.4
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• pp.346-359
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• 2002

The brominated flame retardants (BFRs) are one of the unregulated pollutants in Korea, which is recently highlighted the new pollutants of environmental contamination. In this study, the previous research papers related the BFRs were surveyed, and the analytical methods of BFRs were established. The results are followed; The 40 kinds of PBDEs standards were used to establish the analytical methods to perform the experiments of recoveries and detection limits in water and soil. The detection limits of PBDEs using GC/MS represented 5.0~10.0 pg/L for water and 0.5~2.0 ng/g for soil samples. The average recoveries of water samples were 89~98% with ethylacetate, n-hexane and dichloromethane, and 89~103% in combined solvent with n-hexane and acetone. In soxhlet extraction, the higher recoveries obtained the acetone:n-hexane(1:1) comparing with acetone:dichloromethane(1:1).

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.967-972
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• 1997

Recovery of aromatics in extract phase which was obtained by batch equilibrium extraction between light cycle oil(LCO) and dimethylsulfoxide(DMSO) solution as solvent was investigated by re-extraction. To select the most suitable re-extraction solvent for recovery of aromatics in extract phase, distribution equilibrium was measured between extract phase and solvents. The solvents used were benzene(B), toluene(T), m-Xylene(mX), n-hexane(Hx) and n-hexane(Hx) and n-Octane(Ot). From the distribution coefficients and yields of aromatics, Hx seemed to be the most suitable. Furthermore, effects of operation parameters for re-extraction of aromatics in the extract phase were studied by batch equilibrium re-extracion with Hx as solvent. Yields of aromatics were found to increase with increasing solvent/feed (extract phase) mass ratio(S/F), while distribution coefficients of aromatics were fixed irrespective of S/F used. Operating temperature did not affect distribution coefficients and yields of aromatics. Distibution coefficients and yields of naphthalene group(carbon numer : 10~12) increased with increasing cabon number. Mass transfer rates of aromatics were also measured with a batch stirred vessel.

• Bulletin of the Korean Chemical Society
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• v.18 no.4
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• pp.355-356
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• 1997

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.341-353
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• 2000

The purpose of this study is to investigate the characteristics of pollutants overflow on storm events and the first flush analysis in industrial complex. Eight sub-basins in the Chongju industrial complex were selected for sampling and study with different characteristics during the period from June 1997 to August 1998. Water quality parameters of stormwater runoff such as $BOD_5$, COD, SS, TKN, $NO_3-N$, $PO_4-P$, TP, n-Hexane extracts, Cr, Cu, Pb and Fe were analyzed. During the storm events, measured concentration ranges of $BOD_5$, COD, SS, $NO_3-N$, TKN, $PO_4-P$, TP, r-Hexane extracts, Cr, Cu, Pb and Fe were 2~324 mg/L, 5~810 mg/L, 1~1,110 mg/L, 0.01~10.89 mg/L, 0.1~59.8 mg/L, 0.08~7.02 mg/L, 0.1~7.8 mg/L, 0.1~1,723.6 mg/L, 0.001~0.363 mg/L, 0.001~0.488 mg/L, 0.001~1.28 mg/L, and 0.26~18.91 mg/L, respectively in the industrial complex watersheds. And a quantitative of first flush has been presented. First flush occurs more frequently as the ratio of impervious area increases.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.569-575
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• 1993

The addition of Sn to Pt/${\gamma}$-$A1_2O_3$ catalyst greatly enhanced the activity and decreased the deactivation rate for the dehydrocyclization of paraffins. For the dehydrocyclization of n-octane, there appeared to be an optimal ratio of Pt:Sn=1:4 for 0.75 wt% Pt/${\gamma}$-$A1_2O_3$ catalyst. The addition of K to Pt/${\gamma}$-$A1_2O_3$ also produced a similar effect on the dehydrocyclization of n-hexane. In the case of n-octane, the addition of K led to a less selective catalyst.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.320-324
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• 2002

Binary cure system is composed of different two cure accelerators, which can cause a synergy effect to delay the scorch time and to increase the cure rate. In this study, binary cure systems between 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)-hexane (DBTH) and benzothiazole sulfenamides were investigated using carbon black-filled natural rubber compounds. N-Cyclohexyl-2-benzothiazole sulfenamide (CBS), N-tert-butyl-2-benzothiazole sulfenamide (TBBS), and 2-(morpholinothio) benzothiazole (MOR) were employed as benzothiazole sulfenamides. The binary cure systems show scorch safty at high temperature. The binary cure systems have faster cure rate and better reversion resistance than the single cure system of the benzothiazole sulfenamides. DBTH is found to be more effective to decrease the viscosity of a compound than the benzothiazole sulfenamides. Physical properties of the vulcanizates with the binary cure system are better than those of the vulcanizates with the single one.

• Korean Journal of Plant Resources
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• v.25 no.2
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• pp.176-183
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• 2012

This study was carried out to develop ferns as the natural antioxidant materials by graduating and extracting fronds of $Dryopteris$ $crassirhizoma$, $Dryopteris$ $nipponensis$, and $Polystichum$ $lepidocaulon$, which belong to Dryopteridaceae, using solvent, and analyzing the antioxidant effect of each fraction. The n-butanol fraction of $D.$ $crassirhizoma$ (550.0 $mg{\cdot}g^{-1}$), the ethyl acetate fraction of $D.$ $nipponensis$ (374.8 $mg{\cdot}g^{-1}$), and the n-butanol fraction of $P.$ $lepidocaulon$ (781.8 $mg{\cdot}g^{-1}$) showed relatively higher total contents of polyphenol. The chloroform fraction of $D.$ $crassirhizoma$ (72.9 $mg{\cdot}g^{-1}$), and the n-hexane fraction of $D.$ $nipponensis$ (72.9 $mg{\cdot}g^{-1}$) and $P.$ $lepidocaulon$ (154.5 $mg{\cdot}g^{-1}$) contained relatively higher total contents of flavonoids. DPPH radical scavenging activity was most excellent in the n-butanol fraction of $D.$ $crassirhizoma$ ($RC_{50}=0.02mg{\cdot}mL^{-1}$) and $P.$ $lepidocaulon$ ($RC_{50}=0.04mg{\cdot}mL^{-1}$), and the water fractions of $D.$ $nipponensis$ ($RC_{50}=0.01mg{\cdot}mL^{-1}$). ABTS radical scavenging activity was potent in the n-hexane and n-butanol fractions of $D.$ $crassirhizoma$ (each $RC_{50}=0.02mg{\cdot}mL^{-1}$), the ethyl acetate fraction of $D.$ $nipponensis$ ($RC_{50}=0.03mg{\cdot}mL^{-1}$), and the n-butanol fraction of $P.$ $lepidocaulon$ ($RC_{50}=0.06mg{\cdot}mL^{-1}$). There was the large amount of total polyphenol content in the n-butanol fraction of $D.$ $crassirhizoma$ and $P.$ $lepidocaulon$, and their radical scavenging activities were potent. Therefore, it was thought that biologically active substances of each fraction layer are required to be analyzed and used.

• Macromolecular Research
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• v.11 no.4
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• pp.231-235
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• 2003

Phase behavior information is necessary for accomplishing homogeneous copolymerization to obtain high yield of copolymers and prevent a fouling problem. Cloud-point data to $160^{\circ}C$ and 1,450 bar are presented for five $C_6$ hydrocarbon solvents, normal hexane, 2,2-dimethyl butane, 2,3-dimethyl butane, 2-methyl pentane, and 3-methyl pentane, with poly(ethylene-co-53 mol% norbornene) ($PEN_{53}$). The pressure-concentration isotherms measured for $PEN_{53}$/n-hexane have maximums that range between 5 and 12 wt% $PEN_{53}$. The cloud-point curves for $PEN_{53}$ all have negative slopes that decrease in pressure with temperatures. The single-phase region of $PEN_{53}$ in n-hexane is larger than the regions in 2,2-dimethyl butane, 2,3-dimethyl butane, 2-methyl pentane, and 3-methyl pentane. The cloud-point curve of $PEN_{53}$ in 2,2-dimethyl butane is located at higher temperatures and pressures than the curve in 2,3-dimethyl butane due to the reduced dispersion interactions with and limited access of 2,2-dimethyl butane to the copolymer. Similar cloud-point behavior is observed for $PEN_{53}$ in 2-methyl pentane and 3-methyl pentane.

• Journal of Forest and Environmental Science
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• v.21 no.1
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• pp.16-23
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• 2005

The leaves of Paulownia Coreana Uyeki were collected, extracted with acetone-$H_2O$(7:3, v/v), fractionated with n-hexane, methylene chloride and ethylacetate, and freeze dried to give some dark brown powder. The ethylacetate soluble mixture was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. Spectrometric analysis such as NMR and MS including TLC were performed to characterize the structures of the isolated compounds. From the ethylacetate fraction, five flavonoides and three phenolic acids were isolated and determined.