• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1618-1622
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• 2003

The photochemical reactions of methanolic nalidixic acid (NAL) solution in the absence and in the presence of air have been investigated using 300 nm UV light. From the reactions, 1-ethyl-7-methyl-4-oxo-4-hydro-1,8-naphthyridine (EMDN),formic acid, and formaldehyde are produced. In the presence of air, hydrogen peroxide is also detected along with the products listed above. The presence of oxygen during the irradiation of methanolic NAL solution effects on the product yield. The initial quantum yields of the products and of the NAL decomposition are determined. Possible reaction pathways for the photochemical reaction are suggested on the basis of the products analysis.

• Archives of Pharmacal Research
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• v.16 no.1
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• pp.57-61
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• 1993

Based on the turbidimetric response of protein with 50% trichloroacetic acid (TCA), this study aims to introduce an assay method for protein in solution. The standard procedure consists of mixing equal volume of sample solution (standard or unknown) with 50%-TCA solution and measuring the absorbance at 450 nm after 20 min. The absorbances of the solutions were almost stable over 120 min at room temperature. This assy method is simple, reproducible, and tolerant to many interfering substances. It can detect less amount than $10\mu$g/ml of bovin serum albumin. The assay method has low protein-to-protein variability over wide range of molecular weight.

• Journal of Environmental Science International
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• v.17 no.6
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• pp.671-677
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• 2008

We studied to determine quantitatively the radical species generated from humic acid (HA) solutions by irradiation(>400 mn). The formation of radical species from HA solutions was investigated with ESR spectroscopy. We gave ESR spectrum with g-value 2.0048 and line width 0.559mT, coincided with those of the semiquinone radical. 0.1 mg/L HA solution generated the radicals of $1.2{\times}10^{-6}M$, increased with increasing HA concentration. Also, pH and ionic strength effect of the amount of the semiquinone radical generate from HA solution. In this study, we have found that the singlet oxygen affects the semiquinone radicals generation in HA solution.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.209-212
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• 2002

Main radionuclides of the soil waste stored in Korea Atomic Energy Research Institute are Co-60 and Cs-137. Moisture content of soil is 12%, pH of soil is 5.8, and content of organic matter is 2.2 %. Radioactive concentrations of the soil particle size of which is less than 0.063mm and soil in the drum surface of which is more than radiation dose rate 0.05mR/hr are higher. Meanwhile, radioactive concentration of soil in the drum surface of which is less than radiation dose rate 0.02 mR/hr are mostly lower. On using the mixing solution of ammonium sulfate and citric acid, 62% Co was removed from soil and 41% Cs was removed. Also, on using the mixing solution of ammonium nitrate and citric acid, 61% Co was removed from soil and 39% Cs was removed, and on using the mixing solution of ammonium potassium oxalate, 36% Co was removed and only 3% Cs was removed. And on using only water, removal efficiency is less than 5%.

• Journal of Pharmaceutical Investigation
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• v.15 no.2
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• pp.83-90
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• 1985

The effects and the optimum manufacturing conditions for the preparation of synthetic aluminum silicate which has acid-consuming power and adsorbing capacity were investigated. The results are as follows: 1. The adsorbing capacity was affected by the mixing order of the reactants, that is, the excellent ones were obtained by the method which add the sodium silicate solution to the potassium alum solution. 2. Even though preparing by the bane manufacturing condition, the acid-consuming power is superior to the adsorbing capacity. 3. According to the Box-Wilson Plan, the optimum reaction conditions are concentration of sodium silicate solution; 38% w/w, settling time; 43 hours at room temperature, drying time; 13 hours at $110^{\circ}C$.

• Journal of Applied Biological Chemistry
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• v.48 no.4
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• pp.213-217
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• 2005

Microbial hydrogel was prepared with poly(${\gamma}$-glutamic acid) produced from Bacillus subtilis BS62 using crosslinking reagent, ethylene glycol diglycidyl ether (EGDE), and its physico-chemical characteristics were examined. Hydrogel which prepared from 10 grams of 10% PGA solution with $600\;{\mu}l$ of EGDE at $50^{\circ}C$ for 17 h swelled 4,320 times its dry weight, and time to reach swelling equilibrium in deionized water at 4 to $45^{\circ}C$ range was about 20 h. Swollen hydrogel shrunk in ionic solutions, and rate of shrinkage was higher in calcium chloride solution than sodium chloride solution. Swelling rate of hydrogel increased 1.3-fold of initial swelling rate for 30 min at $80^{\circ}C$.

• The Research Journal of the Costume Culture
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• v.11 no.3
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• pp.441-446
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• 2003

Water-insoluble chitosan with molecular weight of 2,000,000, 500,000, 80,000, and 40,000 and more than 90% of degree of deacetylation were used to test antibacterial activity of chitosan against a pathogenic bacteria, methicillin resistant Staphylococcus aureus(MRSA), which is being issued in the world. As experimental method, Agar plate Smear Method and Agar plate Contact Method were used. The moleculur weight of chitosan didn't exert significant influences on its antibacterial activity against MRSA but chitosan having molecular weight 40,000, 80,000 and 150,000 showed the excellent antibacterial activity. The antibacterial efHciency was excellent in applying it after chitosan was dissolved in acetic acid solution, while the antibacterial efficiency was not expressed nearly in case of applying after chitosan was dissolved in neutral water. Therefore, it is considered that chitosan can show the antibacterial efficiency only if a positive ion status of -NH₃/sup +/ is maintained. MIC of chitosan/acetic acid solution and cotton fabrics finished with chitosan/acetic acid solution showed in concentration of 0.05%.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.124-129
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• 2005

Copper oxide, CuO, are very important components include of high temperature super- conductors, and widely used. The properties of sintered materials were affected by the size and shape of copper oxide with starting materials in the solid-phase reaction. A homogeneous and fine CuO powder was prepared by thermal decomposition of the copper oxalate precursor. Copper oxalate was precipitated by the addition of copper nitrate solution to an oxalic acid solution. The influence of various factors such as temperature, pH, concentration as well as ultrasonic irradiation in the solution were investigated.

• Macromolecular Research
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• v.16 no.7
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• pp.631-636
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• 2008

The intrinsic viscosities were determined for poly(DL-lactic acid) (PDLLA) solutions in 1,2-dialkyl phthalate at temperatures ranging from 30 to $60^{\circ}C$. A series of dialkyl phthalate, in which the alkyl group was changed from methyl to propyl, was used as the solvent to control the solvent quality systematically. The intrinsic viscosity of the PDLLA solution was higher in the better quality solvent, with a higher molecular weight of PDLLA, and at lower temperatures. The unperturbed dimensions of the PDLLA molecule and polymer-solvent interaction parameter of PDLLA in dialkyl phthalate were deduced using extrapolation methods based on the temperature-dependent intrinsic viscosities. Slight shrinkage in the unperturbed chain dimension was observed, which resulted from a change in polymer conformation with temperature. It was also observed that the polymer-solvent interaction became more favorable with the dialkyl phthalate containing a shorter alkyl chain.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.1
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• pp.63-74
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• 2011

The degradation characteristics of 2-chlorophenol(2-CP) by Ferrate(VI) were studied. The degradation efficiency of 2-CP in aqueous solution was investigated at various values of pH, Fe(VI) dosage, initial concentration and aqueous solution temperature. The maximum degradation efficiencies of 2-CP were obtained at pH 7.0 and aqueous solution temperature of 25$^{\circ}C$. The degradation efficiency was proportional to dosage of Fe(VI). Also, the initial rate constant of 2-CP degradation increased with decreasing of the 2-CP initial concentration. In addition, the degradation pathway study for 2-CP was conducted with GC-MS analysis. Acetic acid, formic acid, benzaldehyde and benzoic acid were identified as reaction intermediates of the 2-CP degradation by Ferrate(VI).