• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.199-208
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• 1994

Analytical methods for the determination of the derivatives of the herbicide (${\pm}$)-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) by capillary column gas chromatography with mass spectrometer (GC-MS) and electron-capture detection (GC-ECD) were studied. A successful procedure was introduced for the ester preparation using $H_2SO_4$, as the catalyst and the alcohol 2,2,2-trichloroethanol (TCE) or 2,2,2-trifluoroethanol (TFE). The identificaiton and elucidation of MCPP by GC-MS spectrometry following the esterification with diazomethane, $BF_3$/methanol, $H_2SO_4$/methanol, TCE, TFE, or pentafluorobenzyl bromide (PFB) were carried out. A comparison of the response-sensitivities among those MCPP esters was made with GC-ECD. Although the methylation product of MCPP was confirmed by GC-MS, its low sensitivity to the ECD limited the detection of MCPP. TCE, TFE, and PFB derivatization methods resulted in a high rate of MCPP esterifications and very sensitive ECD molecular responses. Based on efficiency, convenience, worker safety, and least sample contamination, TFE esterificaiton was considered as the superior method for MCPP analysis to the other methods of derivatization. An accurate method is described for quantifying MCPP in soil leachates by GC-ECD at very low concentrations without the requirement of a complicated clean-up process. As a result, MCPP residues at concentrations of less than $0.1{\mu}g$ in 100ml soil leachate were detected.

• School Mathematics
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• v.15 no.4
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• pp.833-846
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• 2013

In this paper, the real state of using terms 'product', 'place value', 'nine-nine', and 'numeral' incorrectly or inconsistently in the area in Korean elementary school 1-2 grade math textbooks/workbooks are analyzed. Based on this analysis, the following four conclusions are presented. First, 'Product' should be defined in the ${\ll}$Math 3${\gg}$ textbook like 'sum' and 'difference'. Multiplication is introduced in the ${\ll}$Math 3${\gg}$ textbook/workbook, however, the result of that calculation is not referred to 'product'. Second, there is a need to reconsider the using the term 'place value' in 2nd elementary mathematics. In the ${\ll}$Math 3${\gg}$ and the ${\ll}$Math 4${\gg}$ textbooks/workbooks are not using the term 'place value' clearly. Third, the word 'addition nine-nine table' and 'subtraction nine-nine table' should not be used in the ${\ll}$Math 2${\gg}$ and the ${\ll}$Math 4${\gg}$ textbooks. Using the term 'multiplication nine-nine' and 'multiplication nine-nine table' in elementary school mathematics textbooks/workbooks instead of using the term 'nine-nine' and 'nine-nine table' respectively would be the possible cause of these inaccurate derivatives. Fourth, in 1st and 2nd elementary mathematics 'numeral' and 'number' should be used discriminately. There is a need to reconsider the using the term 'number' uniformly if possible.

• Journal of Food Hygiene and Safety
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• v.23 no.3
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• pp.191-197
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• 2008

This work was intended for the identification of markers that are found only in the spoiled red pepper powder. When analyzed by GC/MASS, the spoiled red pepper powder contains characteristic naphthalene derivatives, 1, 2, 3, 5, 6, 7, 8, $8\alpha$-octahydro-1, $8\alpha$-dimethyl-7-(1-methylethenyl)-naphthalene and 2-isopropenyl-$4\alpha$, 8-dimethyl-1, 2, 3, 4, $4\alpha$, 5, 6, $8\alpha$-octahydronaphthalene, which have not found in the normal red pepper powder. In addition, microscopic observation and microbial enumeration of the red pepper powder had been performed. Images by scanning electron microscopy showed that the surfaces of spoiled pepper powder were rough with many kinds of microbes, compared with those of normal red pepper powder. A good correlation between the bacterial and fungal counts in the same sample was observed and could be clearly classified into two groups, the normal and the spoiled group, by difference in the microbial counts. These results suggest that the spoiled red pepper powder can be identified by a combination of GC/MASS, microbial counts, and scanning electron microscopy.

• Journal of Food Hygiene and Safety
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• v.23 no.1
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• pp.73-79
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• 2008

The productions of beauvericin and enniatins H, I, and MK1688 by Fusarium oxysporum KFCC 11363P were investigated on rice substrate at four temperatures (15, 20, 25, and $30^{\circ}C$) and three moisture contents (10, 20, and 40%). The largest amount of beauvericin ($718.0\;{\mu}g/g$) was produced at $25^{\circ}C$, and maximum levels of enniatin H ($781.9\;{\mu}g/g$), I ($725.8\;{\mu}g/g$), and MK1688 ($425.8\;{\mu}g/g$) were measured by high pressure liquid chromatography (HPLC) at the same temperature. The optimal moisture content for the production of beauvericin and enniatins H, I, and MK1688 was 40%, and the trace amounts of these toxins were observed at 10% moisture content. Sixty five grain samples (n=65) were tested for the monitoring of beauvericin. This mycotoxin was detected in six grain samples including three maize, two barley, and one wheat samples. The highest contamination level of beauvericin was observed in maize sample ($0.23\;{\mu}g/g$).

• Korean Journal of Food Science and Technology
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• v.41 no.5
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• pp.522-527
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• 2009

The principal objective of this study was to assess the effects of various manufacturing conditions of soy sauce containing hydrolyzed vegetable protein (HVP) (HVP-soy sauce) on 3-monochloropropane-1,2-diol (3-MCPD) contents. Various HVP soy sauces were prepared under different conditions of alkaline treatment and retention process. Derivatives of heptafluorobutylimidazole (HFBI) 3-MCPD were determined via GC/MS below $0.010{\mu}g/g$, which was sensitive with a good recovery rate. The quantity of 3-MCPD decreased with the pH and temperature of alkaline treatment, and the time and temperature of the retention process increased. Alkaline treatment at pH 10.0-10.5 and a 72 hr retention process were shown to reduce effectively the 3-MCPD contents of HVP-soy sauces. This result indicates that the manufacturing process, particularly alkaline treatment, and retention process would be critical steps in managing 3-MCPD contents in HVP-soy sauce.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1097-1103
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• 2006

The divalent antibody-toxins are expected to have increased binding avidities to target cells because of the two cell-binding domains. However, previous studies showed that the refolding yield of divalent antibody-toxin is very low, and it is assumed that homodimer formation of antibody-toxin is strongly interfered by the repulsion between the two large toxin domains that come close to each other during dimer formation. In this study, B3 antibody was used as a model antibody, and its Fab domain was used to construct three different kinds of Fab divalent molecules, $[B3(Fab)-toxin]_{2}$. The monomer Fab-toxin molecules were made by fusing the Fab domain of monoclonal antibody B3 to PE38, a truncated mutant form of Pseudomonas exotoxin (PE), and a connecting sequence that contained spacer amino acid sequence (G4S)n (n=l, 2, 3) was inserted between Fab and PE38. The prepared divalent molecules were $[Fab-S\;1,\;2,\;3-PE38]_{2}\;(=[Fab-SKPCIST-KAS(G_{4}S)nGGPE-PE38]_{2}\;(n=1,\;2,\;3))$, and they are derivatives of previously studied $[Fab-H2cys-PE38]_{2}\;(=[Fab-SKPCIST-KASGGPE-PE38]_{2})$. In $[Fab-Sl,\;2,\;3-PE38]_{2}$, two Fab-S1, 2, 3-PE38 monomers were covalently linked by the disulfide bond bridge made from cysteine in the -SKPCIST- sequence. The insertion of spacer amino acids after the disulfide bridge resulted in a 12-18 fold higher yield of dimer formation than previously constructed $[Fab-Hlcys-PZ38]_{2}[7]$, 3-4-fold higher than $[Fab-ext-PZ38]_{2}[25]$. These two molecules have less amino acid spacer sequence between the disulfide bridge and PE38 domain. The design of $[Fab-PE38]_{2}$ in this study gave molecules with a higher refolding yield. The results of cytotoxicity assay showed a higher cytotoxic effect of these divalent molecules than that of the monovalent scFv-PE38 molecule.

• Microbiology and Biotechnology Letters
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• v.40 no.2
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• pp.104-110
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• 2012

Glycosynthase is an active site nucleophile mutant enzyme, prepared from glycosidase, which is capable of synthesizing oligosaccharide derivatives without the hydrolysis of the product. Thermoacidophilic ${\alpha}$-glucosidase of Thermoplasma acidophilum (AglA) exhibits a transglycosylating activity yielding various glycosides. AglA was converted to glycosynthase by the substitution of the catalytic nucleophile Asp-408 residue into non-nucleophile glycine in order to increase its ability to synthesize various glycosides by transglycosylation. The glycosynthase mutant was purified by Ni-NTA chromatography and its glycoside-synthesizing activity was measured by using an external nucleophile, sodium formate buffer, providing maltose as a donor and p-nitrophenyl-${\alpha}$-D-glucopyranoside ($pNP{\alpha}G$) as an acceptor, respectively. In addition, $pNP{\alpha}G$ was examined for its feasibility to act as both a donor and an acceptor, and products were compared with those of the wildtype enzyme. The mutant enzyme was found to catalyze the formation of a specific product from $pNP{\alpha}G$ with a yield of 42.5% without further hydrolysis, while the wild-type enzyme produced two $pNP{\alpha}G$ products at low yields. The results demonstrate the possibility of satisfactory yields for the reactions in the presence of small amounts of acceptor, and demonstrate that the high activity of the mutant, at pHs below neutrality, was applicable in the transfer of glucose from the natural donor.

• Analytical Science and Technology
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• v.31 no.2
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• pp.78-87
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• 2018

Asian lacquer has been used as an adhesive and coating material in Asian countries, such as China, Japan, and Korea, and other southeast Asian countries. In this study, the changes in the chemical structure of lacquer with drying was analyzed using pyrolysis/GC/MS (which is useful in analyzing polymeric material) to understand its drying procedures. Upon increasing temperature, the dried lacquer was fully pyrolyzed above the pyrolysis temperature of $500^{\circ}C$. The repeatability was good at the pyrolysis temperature of $500^{\circ}C$ (rsd = 2.6-22.3 %); however, there were differences in the pyrogram patterns when the difference in sample quantity was large. The characteristic peaks of Asian lacquer components, such as those corresponding to 1,2-benzenediol and 3-methyl-1,2-benzenediol, were detected and the compound of each peak was assigned according to the mass library. As the lacquer dried, the composition of pyrolysis products with urushiol derivatives bearing 3 C=C bonds was severely reduced compared with the ones with no C=C bonds, indicating that the polymerization is related to C=C bonds. These results can be applied to confirm the presence of lacquer in excavated relics and to monitor the changes in the composition of raw lacquer with drying.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3252-3260
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• 2012

2,2'-Bipyridinium chlorochromate[$C_{10}H_8N_2HCrO_3Cl$] was synthesized by the reaction of 2,2'- bipyridine with chromium(VI) trioxide in 6M HCl. The structure was characterized by IR and ICP analysis. The oxidation of benzyl alcohol using 2,2'-bipyridinium chlorochromate in various solvents showed that the reactivity increased with the increase in the order of the dielectric constant(${\varepsilon}$), in the order: cyclohexene< chloroform$p-CH_3$, H, m-Br, $m-NO_2$) in N,N'-dimethylformamide. Electron-donating substituents accelerated the reaction, whereas electron acceptor groups retarded the reaction. The Hammett reaction constant(${\rho}$) was -0.64(303K). The oxidation reactivity of alcohols can be a useful factor to study about physical properties such as thermal stability, when the polysilsesquioxane solution is ready for an applying coating agent. The observed experimental data was used to rationalized the hydride ion transfer in the rate-determining step.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.495-499
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• 2014

Estrogens are considered the major breast cancer risk factor, and the carcinogenic potential of estrogens might be attributed to DNA modification caused by derivatives formed during metabolism. $17{\beta}$-estradiol ($E_2$), the main steroidal estrogen present in women, is metabolized via two major pathways: formation of 2-hydroxyestradiol (2-OH $E_2$) and 4-hydroxyestradiol ($4-OH\;E_2$) through the action of cytochrome P450 (CYP) 1A1 and 1B1, respectively. Previous reports suggested that $2-OH\;E_2$ has putative protective effects, while $4-OH\;E_2$ is genotoxic and has potent carcinogenic activity. Thus, the ratio of $2-OH\;E_2/4-OH\;E_2$ is a critical determinant of the toxicity of $E_2$ in mammary cells. In the present study, we investigated the effects of berberine on the expression profile of the estrogen metabolizing enzymes CYP1A1 and CYP1B1 in breast cancer MCF-7 cells. Berberine treatment produced significant induction of both forms at the level of mRNA expression, but with increased doses produced 16~ to 52~fold greater induction of CYP1A1 mRNA over CYP1B1 mRNA. Furthermore, berberine dramatically increased CYP1A1 protein levels but did not influence CYP1B1 protein levels in MCF-7 cells. In conclusion, we present the first report to show that berberine may provide protection against breast cancer by altering the ratio of CYP1A1/CYP1B1, could redirect $E_2$ metabolism in a more protective pathway in breast cancer MCF-7 cells.