• Analytical Science and Technology
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• v.13 no.2
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• pp.234-240
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• 2000

The efficiency of Photocatalytic Oxidation Process were investigated for the treatment of Aquatic Humic Substances (AHS). In UV-only system, pH 7-9 was the optimum pH range for TOC removal, and alkali range was the optimum pH for absorbance decrease. In UV/$TiO_2$ system, the optimum $TiO_2$ dosage was 50ppm and over 50ppm of $TiO_2$ dosage was not effective for removal of AHS. In UV/$H_2O_2$ system, optimum $H_2O_2$ dosage was 20mM, when over 20mM dosage, removal of TOC (Total Organic Carbon) and absorbance was decreased. Radical scavenger affected on the photo-oxidation of AHS. Removal rate of TOC and absorbance was decreased by addition of carbonate ions and TOC removal was more effected than that of absorbance.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.259-262
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• 1995

Oxidative stabilities of fat in DHA(cis-4,7,10,13,16,19-docosahexaenoic acid)-added dry milk and ordinary dry milk during storage were studied by determining thiobarbituric acid values of samples. Two kinds of milk powder samples were purchased in the local supermarket and $2{\pm}0.05\;g$ of samples were transferred into serum bottles, which were stored under the light or under dark The oxidation of fat in DHA-added milk powder was higher than that of fat in ordinary milk powder and the acceleration was more evident in the presence of light Light and unsaturated fats accelerated synergistically oxidation of milk fat Addition of DABCO(diazabicyclooctane), which is an efficient singlet oxygen quencher, significantly decreased the photooxidation of milk fat This result clearly suggested that singlet oxygen oxidation (Type II reaction) was involved in the system. Deceleration of milk fat oxidation by DABCO was higher in the DHA-added milk powder.

• Journal of Microbiology and Biotechnology
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• v.13 no.3
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• pp.323-331
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• 2003

Bacteria and fungi are fundamental biotic components of natural biogeochemical cycles for metals and metalloids, and play important roles in dissolution, precipitation, oxidation and reduction processes. Some processes catalyzed by microorganisms also have important applications in environmental biotechnology in the areas of ore leaching and bioremediation.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.574-578
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• 2010

Archaebacteria Sulfolobus acidocaldarius contains the highly thermophilic cytochrome P450 enzyme (CYP119). CYP119 possesses stable enzymatic activity at up to $85^{\circ}C$. However, this enzyme is still considered as an orphan P450 without known physiological function with endogenous or xenobiotic substrates. We characterized the regioselectivity of lauric acid by CYP119 using the auxiliary redox partner proteins putidaredoxin (Pd) and putidaredoxin reductase (PdR). Purified CYP119 protein showed a tight binding affinity to lauric acid ($K_d=1.1{\pm}0.1{\mu}M$) and dominantly hydroxylated (${\omega}-1$) position of lauric acid. We determined the steady-state kinetic parameters; $k_{cat}$ was 10.8 $min^{-1}$ and $K_m$, was 12 ${\mu}M$. The increased ratio to $\omega$-hydroxylated production of lauric acid catalyzed by CYP119 was observed with increase in the reaction temperature. These studies suggested that the regioselectivity of CYP119 provide the critical clue for the physiological enzyme function in this thermophilic archaebacteria. In addition, regioselectivity control of CYP119 without altering its thermostability can lead to the development of novel CYP119-based catalysts through protein engineering.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1729-1734
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• 2007

The electrochemical behaviors of estrone in the presence of various surfactants were examined with great details. It is found that a cationic surfactant, cetyltrimethylammonium bromide (CTAB), obviously facilitates the electro-oxidation of estrone at carbon paste electrode (CPE) from the significant peak current enhancement and the negative shift of peak potential. Additionally, chronocoulometry and electrochemical impedance spectroscopy (EIS) were also used for further investigation of the electrode process of estrone, indicating that low concentration of CTAB exhibits excellent enhancement effects on the electrochemical oxidation of estrone, greatly enhances the diffusion coefficient and the electron transfer rate. Based on this, an electrochemical method was proposed for the determination of estrone. The oxidation peak current is proportional to the concentration of estrone in the ranges over 9.0 × 10?8 - 8.0 × 10?6 mol/L, and a low detection limit of 4.0 × 10?8 mol/L was obtained for 180s accumulation at open circuit (S/N = 3). Finally, this proposed method was demonstrated using estrone tablets with good satisfaction.

• Journal of the Korean Chemical Society
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• v.47 no.1
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• pp.47-58
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• 2003

Fibrosstatins, which were isolated from the culture broth of Streptomyces catanulae subsp. griseospora, are naphthoquinones which can work as alkylating agents. It is important to synthesize these quinone compounds for the study of their biological activities. In this paper, an efficient method, Hooker oxidation, to control the regiochemistry in the synthesis of fibrostatin B is reported.

• Applied Biological Chemistry
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• v.38 no.5
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• pp.408-413
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• 1995

Investigations of the effects of pickle product ingredients on lipoxygenase (LOX) and methemoglobin (MHG, a nonenzymatic oxidant) catalyzing oxidation of linolenic acid were conducted. In addition, activities of LOX, peroxidase (POD) and catalase (CAT) in dry spices used in pickle products were determined. Some commercial pickle brines were observed to inhibit oxidation of linolenic acid by LOX and MHG. The ingredients in pickle products, such as dill oil emulsion, onion concentrate, oil cassia, polysorbate 80 and turmeric acid, reduced LOX and MHG catalyzed oxidation. Lipoxygenase activity was present in garlic, mustard seed and red pepper. Only in mustard seed, peroxidase activity was observed. Catalase activity was observed in garlic, black pepper, allspice and red pepper.

• Journal of environmental and Sanitary engineering
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• v.18 no.1
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• pp.23-29
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• 2003

The effect of ozone oxidation on bio-degradability of leachate was studied. Ozone oxidation process was used as pre-treatment process to enhance performance of biological process in treating landfill leachate. Optimum ozone injection rate and contact time in this experiment was $160{\;}mg{\;}O_/{\ell}{\cdot}hr$ and 45 minutes, respectively. Bio-degradability was enhanced 5.08% by ozone oxidation. The ratio of ozone demand/DOC concentration was $0.049~0.091{\;}mg{\;}O_3/mg{\;}DOC$. The increase of bio-degradability depending on ozone injection rate(D) and contact time(T) can be expressed as follows ; The rate of bio-degradation of DOC was increased proportionally with the increase of ozone injection rate and contact time irrespective of landfill site age. The increase of bio-degradability by ozone addition was not satisfactory. It is hard to expect significant increase in bio-degradability by ozone treatment only. Thus, it is evaluated that ozone oxidation can not increase biodegradability significantly in concentrated wastewater composed of complex organic compound such as leachate.

• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.1-6
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• 2005

The effect of ozone oxidation on biodegradability of leachate was studied. Ozone oxidation process was used as pre-treatment process to enhance performance of biological process in treating landfill leachate. Optimum ozone dosing rate and contact time in this experiment was $160mg\;O_3/L$ hr and 45 minutes, respectively. Biodegradability was enhanced 5.08% by ozone oxidation. The ratio of ozone demand/DOC concentration was $0.049{\sim}0.091mg\;O_3/mg$ DOC. The increase of biodegradability depending on ozone dosing rate(D) and contact time(T) can be expressed as follows ; ${\Delta}E=0.00479{\cdot}D^{0.773}{\cdot}T^{0.800}$ The biodegradation rate of DOC was increased proportionally with the increase of ozone dosing rate and contact time irrespective of landfill site age. The increase of biodegradability by ozone addition was not satisfactory. It is hard to expect significant increase in biodegradability by ozone treatment only. Thus, it is evaluated that ozone oxidation can not increase biodegradability significantly in concentrated wastewater composed of complex organic compound such as leachate.

• Asian Journal of Atmospheric Environment
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• v.6 no.3
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• pp.137-146
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• 2012

Poor indoor air quality is now worldwide concern due to its adverse impacts on our health and environment. Moreover, these impacts carry a significant burden to the economy. Various technical approaches (e.g., biological, activated carbon fiber (ACF), photocatlytic oxidation (PCO), etc.) have gained popularity in controlling indoor volatile organic compounds (VOCs). This is because removing indoor VOC sources or increasing ventilation rates is often not feasible or economical. This review provides an overview of the various air purification technologies used widely to improve indoor air quality. Although most of these technologies are very useful to remove indoor VOCs, there is no single fully satisfactory method due to their diversity and presence at the low concentration. To achieve technical innovations and the development of specific testing protocols, one should possess a better knowledge on the mechanisms of substrate uptake at VOC concentrations.