• Bulletin of the Korean Chemical Society
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• v.13 no.1
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• pp.26-29
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• 1992

Copolymers with two different side groups, 2,2,2-trifluoroethoxy and p-chlorophenoxy groups, have been synthesized by reaction of poly(dichlorophosphazene) with their sodium salts, and characterized by elemental analysis, gel permeation chromatography, IR and NMR spectroscopies. The molecular weight measurement has shown that the weight average molecular weight, ${\bar{M}}_w$ of the copolymers are all above $10^6$ and their molecular weight distributions are monomodal and narrow (${\bar{M}}_w/{\bar{M}}_n<4$). Thermal properties of these copolymers measured by DSC and TGA exhibited to be intermediate between those of the two corresponding homopolymers.

• Journal of Microbiology
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• v.42 no.2
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• pp.87-93
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• 2004

Twelve mecoprop-degrading bacteria were isolated from soil samples, and their genetic and phenotypic characteristics were investigated. Analysis of 16S rDNA sequences indicated that the isolates were related to members of the genus Sphingomonas. Ten different chromosomal DNA patterns were obtained by polymerase-chain-reaction (PCR) amplification of repetitive extragenic palindromic (REP) sequences from the 12 isolates. The isolates were found to be able to utilize the chiral herbicide meco-prop as a sole source of carbon and energy. While seven of the isolates were able to degrade both (R)-and (S)-mecoprop, four isolates exhibited enantioselective degradation of the (S)-type and one isolate could degrade only the (R)-enantiomer. All of the isolates were observed to possess plasmid DNAs. When certain plasmids were removed from isolates MPll, MP15, and MP23, those strains could no longer degrade mecoprop. This compelling result suggests that plasmid DNAs, in this case, conferred the ability to degrade the herbicide. The isolates MP13, MP15, and MP24 were identified as the same strain; however, they exhibited different plasmid profiles. This indicates that these isolates acquired dif-ferent mecoprop-degradative plasmids in different soils through natural gene transfer.

• Korean Journal of Plant Tissue Culture
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• v.28 no.3
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• pp.123-128
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• 2001

In order to develop the biotechnological methods for the mass production of anticancer compounds from tissue culture of Panax ginseng C.A. Mayer, these studies were carried out for the selection of ginseng cell lines containing higher concentration of polyacetylene compounds and optimal condition for their biosynthesis. Panaxynol, one of ginseng polyacetylene, was not detected in any callus induced from ginseng superior cell lines cultured on MS medium supplemented with $\beta$-chlorophenoxy acetic acid (CPA). Panaxydol, another one of polyacetylene and anticancer compounds, were detected in calli of 5 cell lines by thin layer chromatogram and gas chromatogram. Among the 18 ginseng superior lines, the cell line 30201 has higher content of panaxydol. Especially, panaxydol was not detected in the callus induced from cell line 10301 which cultured on the medium containing CPA only, however, it was detected on the same callus cultured on mixed medium containing CAP 2 mg/L and BA 0.05 mg/L. SH medium was better than MS medium for ginseng callus growth and biosynthesis of polyacetylene, and also found that it was not effected by NAA and sucrose concentration in the culture medium.

• Korean Journal of Weed Science
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• v.2 no.1
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• pp.41-46
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• 1982

Herbicidal effectivity on perennial paddy weeds such as Sagittaria pygmaea Miq. and Eleocharis kuroguwai Ohwi was evaluated. Herbicides used were butachlor [2-chloro-2, 6-dietyl-N(butoxymethyl)-acetanilide], benthiocarb [S-(4-chlorobenzy)-N, N-diethyl-thiocarbamate], molinate (S-ethyhexahyaro-l-Hazpine-carbothiate], SW-751, Chlormethoxynil (2.4-dichlorophenyl-3-methoxy-4-nitrophenyl-ether), CNP (2.4.6-trichlorophenyl-4-nitrophenylether),oxadiazon [2-tertbutyl-4-(2.4-dichloro-S-isopropoxyphenyl)-5-OXO-1.3.4-Oxadiazoline], dinuron [1-dimethyl-benthyl)-3-pheratrylurea], bentazon [3-isopropyl-IH-2.1.3-benzothiadiazine-(4)3H-one-2.2-dioxide], ACN (3-chloro-2-amino-l.4-naphthoquinone), MCPB [4-(2-methyl-4chlorophenoxy), butyric acid], 2.4-D (sodium 2.4-dichlorophenoxy acetic acid), MCP) sodium 2-methyl-4-chlorophenoxy acetic acid), SST-5, TH 63. Graszin D (Bentazon/2.4-D) and Graszin M (Bentazon/MCP) Herbicidal effectivity was divided into three types. Type I was the complete control both leaf and tuber, and SW-751 was belonged to this type. Type II was the partial control that exhibit complete control within certain period after herbicide application. After a certain period, however, the lateral bud have the germinability and grow normally, there after. Chloromethoxynil, CNP, ACN, and Oxadiazon were belonged to this group. Type III was no control at all. For E. kuroguwai, application of CNP, Chloromethoxnil, Oxadiazon and SW-751 gave good control in the early stage shile 2.4-D, MCP, bentazon and glaszin-D controlled well the intermediate stage application. Based on this results, E. kuroguwai can be controlled by herbicide application either in the early stage or in the intermediate stage.

• Applied Biological Chemistry
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• v.23 no.2
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• pp.131-139
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• 1980

TOK (2,4-Dichlolo-4'-nitrodiphenyl ether) was applied to two Korean soils possessing different physico-chemical properties at a certain concentration and incubated for a certain time under flooded conditions. The metabolites and the soil microorganisms involved in the degradation of TOK are studied. Chong Ju and Chung Ju soils treated with TOK at a concentration of 500 ppm and incubated for two, four, and six months at $30^{\circ}C$ yielded 4-chloro-4'-amino diphenyl ether, 2, 4-dichloro-4'-amino diphenyl ether(amino-TOK), N-[4'-(4-chloro-phenoxy)] phenyl acetamide, and N-[4'-(4-chloro-phenoxy)] phenyl formamide as the major metabolites. TOK underwent the reduction of nitrogroup to amino group, dechlorination, acetylation, and formylation. No cleavage at the ether linkage was recognized. TOK was more readily degraded in Chung Ju soil which is characterized by the higher pH (PH 6.43), clay loam in textural class, and the higher cation exchange capacity. The toxicity of TOK as a possible environmental contaminant is expected to be considerably reduced as a result of the above degradation Twelve strains of soil bacteria were isolated from the TOK-treated Chong Ju and Chung Ju soils. As a result of the incubation of TOK in pure cultures of the isolates, T-1-1 strain isolated from Chong Ju soil had almost no degradability, whereas T-2-3 strain turned out to be the most potent. The degradation of TOK by the isolates constituted mostly the reduction of the nitro group to amino group. The citrate buffer extract of Chung Ju soil reduced TOK more readily to amino-TOK than that of Chong Ju soil.

• Journal of the Korean Chemical Society
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• v.59 no.3
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• pp.225-232
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• 2015

A liquid chromatography-electrospray ionization-tandem mass spectrometry method (LC-ESI-MS/MS) was used for determining seven pesticides (2,4-dichlorophenoxyacetic acid, methomyl, aldicarb, 2-methyl- 4-chlorophenoxy- acetic acid, molinate, carbaryl and carbofuran) and two synthetic materials (quinoline and bisphenol-A) in surface water. The analytes were extracted using solid-phase extraction (SPE). The eluate was concentrated by nitrogen gas. 100 microliters of 30% (v/v) methanol aqueous solution were used to dissolve the residue and an aliquot of the reconstituted solution was directly injected into LC-ESI-MS/MS after the filtration using 0.2 μm polytetrafluoroethylene (PTFE) syringe filter. Under the established condition, the calibration curves of the analytes were linear with correlation coefficients of above 0.997. The quantification limit was 0.002~0.011 μg/L and the relative standard deviations were less than 16.4%. In addition, accuracy was in the range of 84~107% and the recoveries were values between 56.2 and 98.6%. In this study, the developed method was applied to the analysis of real surface water samples.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.78-83
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• 1981

This study was attempted to determine the major weed species occurring in Korean turfgrass, Zoysia japonica Steud. and to evaluate the most effective means for controlling them. More or less 40 weed species were determined to occur in Korean turfgrass. In terms of quantity and frequency of occurrence, Trifolium repens L., Digitaria sanguinalis (L.) Scop., Draba nemorosa var. hebecarpa Lindbl, Erigeron canadensis L., and Cyperus amuricus Max were observed to be the major weeds. Simpson's index, 0.306 was obtained to be the major weeds. Simpson's index, 0.306 was obtained in the golf course, Jinryang, Gyungsan-gun, meaning that no specific weed species were dominant, but in Kyungpook National University campus, Trifolium repense L. was a single dominant species, indicating Simpson's index, 0.776. The most effective herbicides to control Trifolium repense L. and other broad leaf weeds were MCPP [2-(2-methyl-4-chlorophenoxy) propionic acid), followed by 2,4-D (2,4-dichlolophenoxy acetic acid). Increased rates of both herbicides increased markedly their effectivity against weeds, with very slight injury against turfgrass. MCPP at 2.8 kg(a.i.)/ha gave excellent control without any injury and 2,4-D at 1.0 kg(a.i.)/ha.

• Journal of Preventive Medicine and Public Health
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• v.35 no.1
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• pp.24-32
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• 2002

Objective : Few studies have examined the relationship between the risk of cancer and exposure to pesticides in Korea or in other East Asian that have until recently used chlorophenoxy herbicides. The aim of this study was to evaluate the relationship between the exposure to pesticides and cancer incidence. Methods : We conducted a prospective cohort study with a follow-up period of 13 years (1985-1998). The subjects included 2,687 male and 3,589 female Kangwha Island residents, Koreans aged fifty-five or more as of March 1985, who received a personal health interview and completed a health examination survey. A Cox proportional hazards models were used to estimate relative risks(RR). Results : At baseline, the mean age of the study participants in 1985 was 66.4 for males and 67.1 for females. During the 13 years follow-up, a total of 300 incidents of cancer in males and 140 in females developed. In males, the total cancer incidence in the highest group was RR, 1.4 (95%. CI=1.0-1.9), p for trend=0.041, for digestive organ cancer Incidence in the highest group, RR, 1.5 (95% CI=1.0-2.3), p for trend=0.057, for stomach cancer, incidence in the highest group, RR, 1.6 (95% CI=0.9-2.8), p for trend=0.094, for gallbladder cancer incidence in the highest group, RR, 9.1 (95% CI=1.1-77.0), p for trend=0.014 were elevated according to the higher frequency of pesticide use per year. In particular, the risk of gallbladder cancer was very high. Although not significant, the risk of liver cancer was higher than in the non-exposed group (in the highest group, RR, 2.0(95% CI=0.7-5.9)). In females, although not significant, breast cancer incidence in the highest exposure group was higher than in the non-exposed group (in the highest group, RR, 4.7 (95% CI=0.5-27.9)). Conclusions : This study demonstrates that Korean farmers who use pesticides, particularly males, have a significantly higher total cancer incidence, particularly from digestive organ cancers such as, stomach, gallbladder, and liver cancer. In particular, the risk of gallbladder cancer was very high.

• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.226-232
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• 1991

Adsorption and oxidation of polychlorinated phenols by suspended ${\sigma}-MnO_2$ in aqueous solution have been studied. Of the proposed mechanism, adsorption reaction of chlorophenols onto ${\sigma}-MnO_2$(s) depended upon the pH of the solution and the concentration of chlorophenol. Adsorption isotherms showed a reasonably good fit to the Langmuir isotherm. From the pH dependence of adsorption partition coefficient and the linear relationship between octanol-water partition coefficient and adsorption partiton coefficient of chlorophenol, it is estimated that adsorption is dominated by its hydrophobicity. The rate of electron transfer reaction evaluated from the rate of reductive dissolution of ${\sigma}-MnO_2$(s) depended linearly upon the concentration of chlorophenol and the pH of medium. Observed rate constants ($K_0$) of the meta-substituted chlorophenol were lower than that of the ortho-or para-chlorophenol because of resonance effect of chlorophenoxy radical. It is indicated that this radical is produced in the adsorption process and the electron transfer reaction is rate determining.