• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.196-201
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• 2000

The influence of adsorption on cadmium toxicity to soil microorganisms in smectite-rich soils and sediments was quantified as a function of solution and sorbent characteristics. Adsorption and surface complexation experiments were conducted to infer Cd sorption mechanisms to a reference smectite and three fractions of a Veritsol soil, and to elucidate the effects of the surface complexation on Cd bioavailability and toxicity in soils and sediments. Cadmium adsorption isotherms conformed to the Langmuir adsorption model, with adsorptive capacities of the different samples dependent on their characteristics. Equilibrium geochemical modeling (MINTEQA2) was used to predict the speciation of Cd in the soil suspensions using Langmuir and Triple Layer surface complexation models. The influence of adsorption and surface complexation on cadmium toxicity to soil microorganisms was assessed indirectly through the relative change in microbial hydrolysis of fluorescein diacetate (FDA) as a function of total Cd concentration and sorbent characteristics. Adsorption decreased the toxicity of Cd to soil microorganisms. Inner-sphere complexation is more effective than outer-sphere complexation in reducing the bioavailability and toxicity of heavy metals in soils and sediments.

• Journal of Applied Biological Chemistry
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• v.51 no.4
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• pp.143-147
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• 2008

Purified atrazine chlorohydrolase (AtzA) was entrapped in the nanoparticles of biomimetically synthesized silica at the ambient condition within 20 min. Entrapped AtzA in biomimetic silica was less affected by pH change and showed higher thermostability than free enzymes. The entrapped AtzA was also more tolerant against proteolysis, with 80% of the initial activity remaining and retained 82% of the initial activity even after four cycles of usage. These results suggest that entrapment of AtzA in biomimetic silica could be utilized under diverse environmental conditions with the active catalytic performance sustained.

• Korea-Australia Rheology Journal
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• v.17 no.2
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• pp.71-77
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• 2005

We investigated thermal, rheological, morphological and mechanical properties of a binary blend of poly(lactic acid) (PLA) and poly(butylene succinate adipate) (PBSA). The blends were extruded and their molded properties were examined. DSC thermograms of blends indicated that the thermal properties of PLA did not change noticeably with the amount of PBSA, but thermogravimetric analysis showed that thermal stability of the blends was lower than that of pure PLA and PBSA. Immiscibility was checked with thermal data. The rheological properties of the blends changed remarkably with composition. The tensile strength and modulus of blends decreased with PBSA content. Interestingly, however, the impact strength of PLA/PBSA (80/20) blend was seriously increased higher than the rule of mixture. Morphology of the blends showed a typical sea and island structure of immiscible blend. The effect of the blend composition on the biodegradation was also investigated. In the early stage of the degradation test, the highest rate was observed for the blend containing $80wt\%$ PBSA.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.368-371
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• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Bioremediation of aromatic hydrocarbons in groundwater and sediments is often limited by dissolved oxygen. Aerobic bioremediation has been highly effective in the remediation of many fuel releases, but Many aromatic hydrocarbons degrade very slowly under anaerobic conditions. Nitrate is a good alternative electron acceptor to oxygen and denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. Because nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. This study show that biodegradation of BTEX and MTBE is enhanced by the nitrate-amended microcosms under aerobic/anaerobic conditons. Although aromatic hydrocarbons degrade very slowly under anaerobic conditions. Biodegradaton was observed for all of the test compounds.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.3-10
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• 1999

The unknown amount of thiolane retained on different soil matrix was characterized by employing an uniquely designed glass vessel, which was forced to purge the prepared slurry sample so that thiolane may diffuse into Tenax/charcoal tube. Thiolane can be recovered ranging from approximately 89 % at 1 ppm regardless of soil types, which was not consequently affected by potential biodegradation during sample preparation. For 5 ppm. thiolane is more recoverable up to 92 % for sand, whereas it was poorly recovered as low as 85 % for clay. It strongly suggests that controls should be considered when soil types varied in a concerned area. The technique was eventually capable of determination of thiolane for the samples taken from the site which led to be taken into consideration for proper site remediation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.159-162
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• 2005

In this study, a two-liquid-phase (TLP) bioreactor was conducted to enhance the biodegradation efficiency and rate of PAH. Phenanthrene was degraded efficiently irrespective of the type and the amount of water-immiscible liquid (WIL). The degradation efficiency of anthracene was much higher in paraffine oil than in silicone oil because the mass transfer of anthracene was different in the two WILs. Pyrene was only transferred from soil to WIL during 5 days. It seemed that the degradation of PAH in the TLP bioreactor was mainly dependent on the mass transfer of PAH.

• Journal of Sericultural and Entomological Science
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• v.42 no.2
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• pp.109-113
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• 2000

The preparation of skin care gauze could be make to mixing separated cellulose from waste milk pack and degummed silk fibroin fiber. Also, its wound covering and anti-bacterial activity were investigated in order to find out the enhancement of their functionality. By the 30% silk fibroin fiber including skin care gauze, the anti-bacterial activity values of Staphylococcus strain are much 4 times higher than of 0∼10% silk fibroin fiber including skin care gauze. The average yield of cellulose from waste milk pack was obtained 50-60%, and their morphologies, physical properties, modulus and biodegradation ratios are studies, respectively.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.502-506
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• 2009

The removal properties of Polyethylene glycols (PEGs) known as the important group of synthetic polymers of ethylene oxide were examined by the bio-reactor equipped with a mesh filter module. PEG-1000 and PEG-2000 were fairly removed on the basis of TOC, which were 75.1% and 51.6%, respectively. In the case of PEG-20000, the removal efficiency of TOC was less than 15.2% and the favorable acclimation of microbes was not obtained. It was suggested that this system could effectively maintain microbes for the biodegradation of low molecular weight of PEG and TOC removal was significantly influenced by PEG molecular weight.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.166-166
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• 2008

The tidal flat of Korea is one of the most dynamic areas in terms of sediment erosion and deposition. Tidal flats provide important food resources, ecological niche for diverse organisms and have functional role of bioremediation by mineralizing organic matters. Generally, microbes are essential constituent for biochemical transformations, such as mineralization of organic matters and biodegradation of pollutants. Understanding microbes in tidal flat sediment is necessary to understand these processes. In order to understand role of microbes in tidal flat, this study investigated prokaryotic communities by several methods such as clone library, DGGE, and pyrosequencing. In addition, quantification of microorganisms and isolation biodegrading bacteria were investigated in tidal flats of Western Coast.

• Journal of Applied Biological Chemistry
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• v.42 no.2
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• pp.57-61
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• 1999

Seven numerically dominant 2-methyl-4-chlorophenoxyacetic acid (MCPA)-degrading bacteria were isolated from agricultural soils. The isolates utilized the herbicide MCPA as a sole carbon source, producing significant biomass in MCPA mineral medium. They exhibited diverse herbicide degradation capabilities, but most of them grew very slowly in mineral medium containing herbicide. The chromosomal DNA patterns of the isolates obtained by polymerase chain reaction amplification of repetitive extragenic palindromic sequences were distinct from each other. One isolate, SH3, which was identified as Sphingomonas species by fatty acid methyl ester analysis, was able to degrade 5 different phenoxyacetic acid herbicides within 4 days. This strain contains two plasmids, and the smaller one has a crucial role in herbicide degradation. MCPA treated into agricultural soils without indigenous MCPA-degraders persisted for a long time, but the application of the isolate SH3 resulted in rapid decline of MCPA concentration in the soil.