• Journal of Korean Society of Environmental Engineers
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• v.32 no.11
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• pp.995-1000
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• 2010

To investigate the relationship between polychlorinated byphenyls (PCBs) sources and concentration level in sediment, total 63 sediment samples with three-time sampling at one site were measured at 21 sites in Nakdong River. As a result of analysis, total concentrations and toxic equivalent (TEQ) concentration of Dioxin-like PCBs were ranged from 3.0 to 6,600 pg/g-dry with a mean value of 440 pg/g-dry and

• Analytical Science and Technology
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• v.5 no.2
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• pp.159-167
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• 1992

An improved and accurate method for the determination of linear alkybenzene sulfonate(LAS) in river water is described by using gas chromatography and GC/MS. The gas chromatograph equipped with BP-5 capillary column was satisfactory for isolation of the homologues and isomers of LAS in river water. Four LAS homologues, $C_{10}$, $C_{11}$, $C_{12}$, $C_{13}$ alkyl chains were determined in Jungrang stream, Jinwi stream and down stream of Han river tributary. Especially $5-C_{11}$, $6-C_{11}$, $2-C_{12}$ and $6-C_{13}$, $7-C_{13}$ of LAS were identified by mass chromatogram. Different composition of LAS in standard and river water expressed the distribution and fate of LAS in river water. The remarkable reduced content of $C_{12}$ and $C_{13}$ in river water implied that the biodegradation of LAS more easily occured in longer alkylchain one. This method would be applicable for determination of LAS in water with high resolution and sensitivity.

• Korean Journal of Microbiology
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• v.43 no.1
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• pp.72-75
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• 2007

Using co-immunoprecipitation, we identified proteins interacting with Streptomyces coelicolor RNase ES, an ortholog of Escherichia coli RNase E that plays a major role in RNA decay and processing. Polyphosphate kinase and a homolog of exoribonuclease polynucleotide phosphorylase, guanosine pentaphosphate synthetase I that use inorganic phophate were co-precipitated with RNase E, indicating a possibility of S. coelicolor RNase ES to form a multiprotein complex called degradosome, which has been shown to be formed by RNase E in E. coli. Polynucleotide phophorylase proteins from these two phylogenetically distantly related bacteria species showed similar RNA cleavage action in vitro. These results imply the ability of RNase ES to form a multiprotein complex that has structurally and functionally similar to that of E. coli degradosome.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.5
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• pp.747-751
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• 2000

This study was carried out to improve the analysis method of gingerol compounds from ginger (Zingiber officinale Roscoe). Pungent components of ginger were extracted by acetone and lisolated by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) with LiChrosorb RP-18 column. Three homologues of gingerols were identified by HPLC-mass spectrometry (LC/MS) and nuclear magnetic resonance (NMR). The contents of [6]-, [8]- and [10]-gingerols in three homologues identified were 635.3 mg%, 206.6 mg% and 145.7 mg% in raw ginger, and were 418.2 mg%, 142.6 mg% and 103.3 mg% in ginger paste, respectively.

• Analytical Science and Technology
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• v.17 no.2
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• pp.184-191
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• 2004

In this study, the separation of toxic dioxin 2,3,7,8-congeners by DB-5MS and SP-2331 GC columns which are widely used in HRGC/HRMS analysis was examined. Through the dioxin analysis of column performance check standard solution and fly ash sample, the isomer specific separation of 2,3,7,8-substituted dioxins from tetra to hexa-isomers on DB-5MS and SP-2331 columns were studied. The effect of I-TEQ value by these columns was also studied. The total concentrations of toxic dioxins for the column performance check standard solution were 508.4 ng/mL analyzed by DB-5MS and 515.8 ng/mL analyzed by SP-2331, respectively. The I-TEQ value obtained by both columns was shown to be almost equivalent for the column performance check standard solution and fly ash sample.

• Korean Journal of Weed Science
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• v.15 no.1
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• pp.85-98
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• 1995

Six malformin B's produced by Aspergillus niger van Tiegh. were separated by HPLC. Their structures determined by the methods of amino acid analyses, mass spectrometry, and two-dimensional NMR were revealed as cyclic pentapeptides structurally related to malformin $A_1$. Both the NMR and MS/MS data suggest that the respective structures of separated malformin B's were as follows; cyclo-D-Cys-D-Cys-L-Val-D-Leu-L-allo-Ile for $B_{1a}$, cyclo-D-Cys-D-Cys-L-Val-D-Leu-L-Leu for $B_{1b}$, cyclo-D-Cys-D-Cys-L-Val-D-Val-L-Leu for $B_2$, cyclo-D-Cys-D-Cys-L-Val-D-Ile-L-Leu for $B_3$, cyclo-D-Cys-D-Cys-L-Val-D-Ile-L-Ile for $B_4$, and cyclo-D-Cys-D-Cys-L-Val-D-Val-L-Ile for $B_5$. Among the malformin B's, the structure of $B_{1b}$ was the same as that of malformin $A_3$ or C. All the malformin B's showed physiological activities in the two assay systems using corn(Zea mays L.) roots and mung bean(Phaseolus aureus Roxb.) hypercotyl segments. The malformin B's with molecular weight 529 were more effective for inducing corn root curvature than those with molecular weight 515. The difference in molecular weight of malformin B's, i.e., the retention time on HPLC, results in the polarity change of the whole malformin molecule which affects the revealation of the malformin activities. In addition, the disulfide form of the malformin B's gives the rigidity of the molecule, whereas the combination of the fourth and the fifth amino acid residues provides the optimal three-dimensional configuration to the malformin receptor of plants. Presumably, these two factors are appeared to be essential for the greatest physiological activity of malformin B's. malformin $B_{1a}$ caused the corn root curvature by 90% at a concentration of $0.25{\mu}M$. However, such differential activities with molecular weight of 529 or 515 of malformin B's were not found in the mung bean hypercotyl segment test. Maximum stimulation of mung bean hypercotyl growth was observed at $0.1{\mu}M$ concentration of malformin B's. The growth of the segments treated with $B_5$ was 154% greater than that of the control.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.385-389
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• 2005

To understand the pollution level by polychlorinated biphenyls (PCBs) in ambient air of industrial area, PCBs concentrations were measured at Sihwa and Banwol industrial region, Korea. The concentrations of total PCB and WHO-TEQ ranged from 2,080 to $5820\;pg/m^3$ (median value is 2,760) and from 0.19 to $1.01\;pgTEQ/m^3$ (median value is 0.42), respectively. In terms of homologues composition the fraction of highly chlorinated biphenyls(from hexa-CB to deca-CB) were higher than the air samples of other regions such as jeonju and yokohama area. The cluster analysis was conducted to study the relation between the air samples and sources such as incinerator flue gases and Aroclor samples. The isomer fractions in the homologue were used as input variables. Based on the results, the industrial ambient air samples were divided from source samples with long Euclidian distance. This suggest that the ambient air samples of Sihwa and Banwol were not on the influence of Aroclor and incinerators. Therefore, further investigation on systematical air monitoring will be required to estimate the sources of PCBs in the above industrial areas.

• The Korean Journal of Pesticide Science
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• v.10 no.2
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• pp.91-98
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• 2006

The objective of this study was to compare dioxin contents in spinach, soil and air and to evaluate the relation of dioxin concentrations in crop and its cultural environment. Sample weighing for the precise peak detection in dioxin analysis was also determined. The fragmentogram of HpCDFs, and especially OCDF, indicated different pattern from that of TeCDD/F, PeCDD/Fs and HxCDDs/Fs, which showed the same pattern. In case of field culture spinach (wet sample 2 kg) in Japan, peak of OCDF could be detected clearly, while market spinach (wet sample 1 kg) showed the only baseline detection. The result makes it possible to suppose the fact that production place of market spinach was not contaminated with OCDF, but atmospheric pattern of production place was similar to that of open field sample. So we could decide that the sample of agricultural crops were needed more than 2 kg in wet weight for the evaluation of precise peak The total tendency of dioxin concentration levels in field culture spinach may be affected by OCDD and HCDF distributed in soil. However, on the whole the major factor seems to be the atmospheric deposition.

• Polymer(Korea)
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• v.33 no.1
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• pp.58-66
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• 2009

The thermotropic liquid crystalline behavior of the homologous series of cellulose tri[4-{4'-(nitrophenylazo) phenoxycarbonyl}] alkanoates (NACEn, n=2$\sim$8, 10, the number of methylene units in the spacer) have been investigated. All of the homologoues formed monotropic nematic phases. The isotropic-nematic transition temperature ($T_{iN}$) decreased when n is increased up to 7, but it became almost constant when n is more than 7. The plot of transition entropy at $T_{iN}$ against n had a sharp negative inflection at n=7. The sharp change at n=7 may be attributed to the difference in arrangement of the side groups. The melting temperature ($T_m$) and associated entropy change at $T_m$, in contrast with $T_{iN}$ and associated entropy change at $T_{iN}$, exhibited a distinct odd-even effect, suggesting that the average shape of the side chains in the crystalline phase is different from that in the nematic phase. The thermal stability and degree of order of the nematic phase observed for NACEn were significantly different from those reported for the homologous series of side-chain and combined type liquid crystal polymers bearing azobenzene or biphenyl units in the side chains. The results were discussed in terms of the differences in the chemical structure, the flexibility of the main chain, the mode of chemical linkage of the side group with the main chain, and the number of the mesogenic units per repeating unit.

• Polymer(Korea)
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• v.32 no.5
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• pp.489-496
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• 2008

The thermotropic liquid crystalline behavior of a homologous series of poly[1-{4-(4' nitrophenylazo) phenoxycarbonylalkanoyloxy}ethylene]s (NAPEn, n = $2{\sim}8$,10, the number of methylene units in the spacer) have been investigated. All of the homologues formed monotropic nematic phases. The glass transition temperatures decreased with n. This is attributed to a plasticization of the backbone by the side chains. The isotropic-nematic phase transition temperatures decreased with increasing n up to 7 and showed the odd-even effect. However it became almost constant when n is more than 7. This behavior was rationalized in terms of the change in the average shape of the side chain on varing the parity of the spacer. This rationalization also accounts for the observed variation of the entropic gain for the clearing transition. The mesophase properties of NAPEn were entirely different from those reported for the polymers in which the azobenzene groups are attached to polyacrylate, polymathacrylate, and polystyrene backbones through polymethylene spacers. The results indicate that the mode of chemical linkage of the side group with the main chain plays an important role in the formation, stabilization, and type of mesophase.