• Mycobiology
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• v.46 no.2
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• pp.138-146
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• 2018

Two-hundred and fifty-five strains of actinomycetes isolated from soil samples were screened for their antagonistic activities against four well-known wood decay fungi (WDF), including a brown rot fungus, Gloeophyllum trabeum and three white rot fungi Donkioporia expansa, Trametes versicolor, and Schizophyllum commune. A dual culture assay using culture media supplemented with heated or unheated culture filtrates of selected bacterial strains was used for the detection of their antimicrobial activity against four WDF. It was shown that Streptomyces atratus, S. tsukiyonensis, and Streptomyces sp. greatly inhibited the mycelial growth of the WDF tested compared with the control. To evaluate the biocontrol efficacy of S. atratus, S. tsukiyonensis, and Streptomyces sp., wood blocks of Pinus densiflora inoculated with three selected Streptomyces isolates were tested for weight loss, compression strength (perpendicular or parallel to the grain), bending strength, and chemical component changes. Of these three isolates used, Streptomyces sp. exhibited higher inhibitory activity against WDF, especially G. trabeum, as observed in mechanical and chemical change analyses. Scanning electron microscopy showed that cell walls of the wood block treated with Streptomyces strains were thicker and collapsed to a lesser extent than those of the non-treated control. Taken together, our findings indicate that Streptomyces sp. exhibits the potential to be used as a biocontrol agent for wood decay brown rot fungus that causes severe damage to coniferous woods.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.829-835
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• 2011

A dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) has been developed as a new approach for the extraction of trace copper in water and beverage samples followed by the determination with flame atomic absorption spectrometry. In the DLLME-SFO, 8-hydroxy quinoline, 1-dodecanol, and methanol were used as chelating agent, extraction solvent and dispersive solvent, respectively. The experimental parameters related to the DLLME-SFO such as the type and volume of the extraction and dispersive solvent, extraction time, sample volume, the concentration of chelating agent and salt addition were investigated and optimized. Under the optimum conditions, the enrichment factor for copper was 122. The method was linear in the range from 0.5 to $300\;ng\;mL^{-1}$ of copper in the samples with a correlation coefficient (r) of 0.9996 and a limit of detection of $0.1\;ng\;mL^{-1}$. The method was applied to the determination of copper in water and beverage samples. The recoveries for the spiked water and beverage samples at the copper concentration levels of 5.0 and $10.0\;ng\;mL^{-1}$ were in the range between 92.0% and 108.0%. The relative standard deviations (RSD) varied from 3.0% to 5.6%.

• Journal of Soil and Groundwater Environment
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• v.23 no.4
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• pp.42-47
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• 2018

E. coli TG1 pBS TOM Green was cultured to produce toluene-o-monooxygenase (TOM). A biosensor system was successfully constructed using purified TOM to effectively detect trichloroethene (TCE) and tetrachloroethene (PCE), which represent some of the major contaminants in groundwater and soil. In order to utilize TOM as a sensor, NADH, a biological oxidizer, was replaced with hydrogen peroxide which is a chemical oxidizing agent. A three-layered sandwich-type sensing tip was fabricated on the outside of the hydrophilic polyvinylidene fluoride membrane. TCE and PCE were applied to the sensor and the hydrogen ions were measured by a fiber optic fluorometer using fluoresceinamine. Calibration curves were obtained for TCE and PCE in the concentration range of 0.2-100 mg/l, and the detection limit of the system was $10{\mu}g/l$ for TCE and PCE.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.217.2-217.2
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• 2003

A liquid chromatography-tandem mass spectrometric (LC/MS/MS) method was developed for the determination of a new anti-angiogenic drug KR-31831 in rat plasma. KR-31831 and internal standard, KR-31543 were extracted from rat plasma with dichloromethane at basic pH. A reverse-phase LC separation was performed on Luna C8 column with the mixture of acetonitrile-ammonium formate (10 mM, pH 4.5) (67:33, v/v) as mobile phase. The detection of analytes was performed using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. (omitted)

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.781-785
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• 2005

A fast and reliable method for the selective separation and preconcentration of $Cu^{2+}$ ions using homogeneous liquid-liquid extraction was developed. A new $\alpha$-dioxime derivative (2H-1,4-benzothioazine-2,3(4H)dionedioxime, Dioxime I) was synthesized and investigated as a suitable selective complexing ligand for $Cu^{2+}$ ions. Zonyl FSA (FSA) was applied as a phase-separator agent under the slightly acidic pH conditions. Under the optimal experimental conditions ([FSA] = 3.2% w/v, [THF] = 19.5% v/v, [Dioxime I] = 1.9 ${\times}\;10^{-3}$ M, and pH = 4.7), 10 ${\mu}g\;of\;Cu^{2+}$ in 5.2 mL aqueous phase could be extracted quantitatively into 80 $\mu$L of the sedimented phase. The maximum concentration factor was 65-fold. The limit of detection of the proposed method was 0.005 ng $mL^{-1}$. The reproducibility of the proposed method, on the 10 replicate measurements, was 1.3%. The influence of the pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the complexing ligand and the effect of different diverse ions on the extraction and determination of $Cu^{2+}$ ions were investigated. The proposed method was applied to the extraction and determination of $Cu^{2+}$ ion in different synthetic and natural water samples.

• Environmental Mutagens and Carcinogens
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• v.18 no.2
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• pp.109-115
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• 1998

Fluorscence in situ hybridization with chromosome-specific probe has been shown to be a valid and rapid method for detection of chromosome rearrangements induced by chemical and physical agents. This method is useful for quantifying structural aberrations, expecially for stable ones, such as translocation and insertion, which are difficult to detect with conventional method in human lymphocyte. In order to use the FISH method as a biodosimeter for monitoring human population exposed to various chemical and physical agent, baseline level of chromosome rearragement was established. Blood from forty four healthy adults were collected and analysed with whole chromosome-specific probes by human chromosome 1,2 and 4. The frequencies of stable translocation were 2.45 per 100 cell equivalent and those of insertion, color juction, acentric and dicentric were 0.32, 3.28, 0.23 and 0.27 per 100 cell equivalent respectively. The frequencies of chromosome rearragements increased with age in both sexes except for dicenrics. From above result, stable aberrations accumulate with age and it may reflect integrated lifetime exposure of adverse environment.

• Journal of the Korean Chemical Society
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• v.51 no.5
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• pp.412-417
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• 2007

A simple prepared paste electrode (PE) of DNA immobilized on a carbon nanotube was utilized for monitoring the antibacterial agent oxytetracycline (OTC), using square-wave anodic stripping voltammetry (SWASV) and cyclic voltammetry (CV). Given these conditions, SWASV and CV working ranges were observed within 1-10 ngL-1 OTC. In the SWASV and CV for OTC concentrations of 0.1 mgL-1, the relative standard deviations (n=15) were 0.068 and 0.067, respectively. At the optimized condition, the detection limit was found to be 0.4 ngL-1 OTC. This method was applied to the hatchery fish tissue.

• Bulletin of the Korean Chemical Society
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• v.28 no.3
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• pp.373-378
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• 2007

A micro organism Agrobacterium tumifacient as an immobilized cell on a solid support was presented as a new biosorbent in a simple and sensitive spectrophotometry determination of Ni(II) in various samples using 4-hydroxy benzaldehyde-4-bromophenyl hydrazone as a color developing agent (λmax 497 nm) at pH 4.0 ± 0.2. Beer's law was obeyed over the range of 0.01-0.1 μg L-1. The molar absorptivity and Sandell's sensitivity were 1.285 × 105 L mol-1cm-1 and 0.007245 μg cm-2 respectively. Under these conditions, the preconcentration factor obtained was 82, and the detection limit achieved was 0.05 μg L-1. The detailed study of various interfering ions made the method more sensitive and selective. The recovery of Ni(II) from various samples range from 97.75 to 99.35%. The present method was successfully applied for the determination of Ni(II) in spiked, natural water and alloy samples. The proposed method was compared with reported methods in terms of Student's ‘t'-test and Variance ratio ‘f'-test which indicates that there is no significant difference between proposed and literature method at 95% confidence level.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.77-82
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• 2009

Thrombin activatable fibrinolysis inhibitor (TAFI) also known as plasma procarboxypeptidase B or U is a 60 kD glycoprotein, which is the major modulator of fibrinolysis in plasma. TAFI is a proenzyme, which is activated by proteolytic cleavage to an active carboxypeptidase B-like enzyme (TAFIa, 35.8 kD) by thrombin/thrombomodulin and plasmin. Modulation of fibrinolysis occurs when TAFIa enzymatically removes C-terminal lysine residues of partially degraded fibrin, thereby inhibiting the stimulation of tissue plasminogen activator (t-PA) modulated plasminogen activation. TAFIa undergoes a rapid conformational change at $37{^{\circ}C}$ to an inactive isoform called TAFIai. Potato tuber carboxypetidase inhibitor (PTCI) was shown to specifically bind to TAFIa as well as TAFIai. In this study, a novel immunoassay TAFIa/ai ELISA was used for quantitation of the two TAFI activation isoforms TAFIa and TAFIai. The ELISA utilizes PTCI as the capture agent and a double antibody sandwich technique for the detection. Low levels of TAFIa/ai antigen levels were detected in normal plasma and elevated levels were found in hemophilia A plasmas. TAFIa/ai antigen represents a novel marker to monitor fibrinolysis and TAFIa/ai ELISA may be a valuable assay for studying the role of TAFI in normal hemostasis and in pathological conditions.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1907-1914
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• 2010

A novel catalytic kinetic method is proposed for the determination of Se(IV), Se(VI) and total inorganic selenium in water based on the catalytic effect of Se(IV) on the reduction of bromate by p-nitrophenylhydrazine at pH 3.0. The generated bromine, $Br_2$ or $Cl_2$ plus $Br_2$ in 0.1 M NaCl (or NaBr) environment efficiently decolorized Calmagite and the reaction was monitored spectrophotometrically at 523 nm as a function of time. In this indicator reaction, bromide acted as an activator for the catalysis of selenium (IV) and a reducing agent for selenium (VI) at pH 3.0, which allowed the determination of total selenium. The fixed time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the calibration graph are linear in the range 1 - 35 ${\mu}gL^{-1}$ of Se(IV) for the fixed time method at $25^{\circ}C$. The detection limit based on statistical $3S_{blank}$/m-criterion was 0.215 ${\mu}gL^{-1}$ for the fixed time method (7 min). All of the variables that affect the sensitivity at 523 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se (IV) determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The RSDs for ten replicate measurements of 5, 15 and 25 ${\mu}gL^{-1}$ of Se(IV) and Se(VI) was changed between 2.1 - 4.85%. Analyses of a certified standard reference material (NIST SRM 1643e) for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. Se(IV), Se(VI) and total inorganic selenium in environmental water samples have been successfully determined by this method after selective reduction of Se(VI) to Se(IV).