• Journal of Applied Biological Chemistry
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• 제59권4호
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• pp.373-377
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• 2016

An extracellular metalloprotease, Btmp, was partially purified from the culture supernatant of Bacillus thuringiensis 29-126, isolated from animal feces collected in a zoological garden in Japan, by ultrafiltration, ammonium sulfate precipitation, and a set of chromatography on Sephadex G-75 and High-Q. The molecular mass of the protease was estimated to be 60 kDa by SDS-PAGE. The enzyme showed optimum activity at $50^{\circ}C$ and pH 6.0, and had a half-life of 14 min at $50^{\circ}C$. The enzyme activity was not influenced by $Na^+$, $K^+$, $As^+$, $Mg^{+2}$, $Ca^{2+}$, $Ba^{2+}$, and phenylmethylsulfonyl fluoride, but it was moderately inhibited by $Zn^{+2}$ at a concentration of 1.0 mM, while the activity was significantly inhibited to less than 50 % by $Cu^{2+}$, $Co^{2+}$, $Cd^{2+}$, and ethylenediaminetetraacetic acid. Interestingly, the enzyme was activated to 178 % by 1.0 mM of $Mn^{2+}$. From these results, it may be suggested that the protease is a novel extracellular manganeseactivated metalloprotease.

• Environmental Analysis Health and Toxicology
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• 제16권1호
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• pp.35-41
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• 2001

Barley or corn tea, which is usually prepared with municipal chlorinated tap water, is commonly consumed by the public as a substitute for the supplied water itself. This is because most people believe that harmful organic and inorganic compounds can be removed from the tap water by the adsorption mechanism during the tea preparation. In this study, three kinds of commercial grain tea materials-roasted barley grains, a tea bag containing barley grain pieces, and roasted corn grains-were tested for metal removal by preparing 1 liter of tea with deionized/distilled water according the manufacturer's recommended preparation procedures, assuming that the water is contaminated with eight selected metals at levels of 50$\mu\textrm{g}$/l. Of the tested teas, barley tea prepared with roasted grains showed the highest removal efficiency for Cu, As, Ni, Co, Pb, and Cd, ranging from 48 to 71%, followed by corn tea with roasted grains and barley tea with a tea bag. Cr was nearly maintained at the initial concentration in all kinds of tea. The Mn levels. however, were elevated during the tea preparation, particularly in both barley teas, probably because the metal was extracted into the water from the tea materials without significant adsorption. Therefore, it should be considered in the ingestion exposure analysis for metals that their concentrations are altered during the tea preparation with roasted barley or corn grain materials.

• 한국응용과학기술학회지
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• 제18권3호
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• pp.186-190
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• 2001

By fabricating the organic light-emitting devices (OLEDs) based on phosphorescent material, the internal quantum efficiency can reach 100%, compared to 25% in the case of the fluorescent material. Thus, the phosphorescent OLEDs have recently been extensively studied and showed higher internal quantum efficiencies then the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs, with the green emitting phosphor, $Ir(ppy)_{3}$, (tris(2-phenylpyridine)iridium). The devices with a structure of $ITO/TPD/Ir(ppy)_{3}$ doped in the host material $/BCP/Alq_{3}/Li:Al/Al$ were fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of $Ir(ppy)_{3}$, we fabricated several devices and investigated the device characteristics. OLEDs doped into BCP by 10% showed the best characteristics. For 10% doped OLEDs, the maximum luminance of was over 10000 $cd/m^{2}$, and the maximum power efficiency was 7.14 lm/W.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.122-126
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• 2011

A new phosphorescent cyclometalated heteroleptic iridium (III) complex with an ancillary ligand of 4-azacrownpicolinate was prepared and its metal ion selective phosphorescent chemosensing behavior was investigated. The new iridium (III) complex exhibits notable phosphorescence quenching for Hg2+ in aqueous 50% acetonitrile solution with respect to the selective phosphorescent detection of various metal ions including $Li^+,Na^+,K^+,Cs^+,Mg^{2+},Ca^{2+},Ba^{2+},Fe^{2+},Ni^{2+},Cu^{2+},Zn^{2+},Ag^+,Pb^{2+},Cd^{2+},Cr^{2+},Cr^{3+}$ and $Hg^{2+}$. The phosphorescence quenching for $Hg^{2+}$ increased linearly with increasing concentration of $Hg^{2+}$ in the range of $10{\mu}M-700{\mu}M$ even in the presence of other metal ions, except for $Cu^{2+}$. Consequently, the new iridium (III) complex has the potential to be utilized for the determination of parts per million levels of $Hg^{2+}$ in aqueous acetonitrile media.

• 한국환경보건학회지
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• 제18권1호
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• pp.76-83
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• 1992

Effect of freeze drying leek against cadmium poisoning on glutathione peroxidase, on glutathione reductase and on glutathione-s-transferase in liver, kidney and testes of the male rats during the administered period. In this experiment, male rats of Sprague-Dawley strain were used. The rats which were fed for 15 weeks were divided into 4 groups basal diet 3% leek added diet basal diet and cadmium in water and 3% leek added diet and cadmium in water. Cadmium was administered ad libitum 100ppm CdCl$_{2}$ in distilled water. The followings are the result of this experiment. 1. Leek enhanced the glutathione peroxidase activities which were reduced by cadmium treatment in liver, kidney and testes but not significance. 2. Leek reduced glutathione reductase activities which were incresed by cadmium in liver, kidney and testes. 3. Leek incresed the activities of glutathfone-s-transferase in liver but not in kidney and but not in testes. 4. Leek incresed glutathione concentration which was decresed by cadmium treatment in liver and kidney but not testes. This experiment showed that leek-addition group had protective effect against cadmium poisoning and alleviated GR and glutathione-s-transferase activities in tissues. Leek incresed activities of glutathione peroxidase in liver, kidney and testes but not significance. Therefore, this experiment concluded that leek defensive power against long term cadmium poisoning.

• 한국환경보건학회지
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• 제18권1호
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• pp.95-104
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• 1992

The influence of selenium to several toxic effects of cadmum, including lethality has been shown following pretreatment with cadmium, zinc and seleniurm Five groups of rats, each consisting of 16 rats, were studied and each group was divided into four subgroups, 4 rats for each subgroup. After subcutaneous pretreatment during 5 days with saline, CdCl$_{2}$ (0.5mg/kg, ZnCl$_{2}$ (13.0mg/kg) and $Na_{2}SeO_{3}$(1.0mg/kg), rats were given intraperitioneal administration of various dosage of or cadium of cadmium and selenium. After giving the challenge dose, cadmium and metallothionein(MT) concentrations were determined in liver and kidney The concentration of cadmium in liver and kideny increased proportionally to the increase of challenge dosage. The simultaneous administration of cadmium and selenium significantly more decrease cadmium concentrations in liver and kidney than those of the administration of cadmium only. However, MT concentrations in liver and kideny were increased by the pretreatment of cacmium, zinc and selenium. Our results suggest that increasing cadmium concentrations, gradully accumulating in the tissues of liver and kidney as a result of the pretreatment, served to induced the synthesis of MT, thus making them resistant to the challenge from cadmium.

• KSBB Journal
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• 제17권1호
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• pp.54-58
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• 2002

소수성 결합을 가지는 커들란 겔의 특성을 이용하여 지용성물질을 포함한 겔을 제조할 수 있었고, 지용성물질의 종류에 따라 건조시킨 겔 속에 상당한 양이 포함되는데, DHA는 건조중량의 90%가지 포함될 수 있었다. 또한, $\beta$-CD의 포접특성을 이용하여 DHA를 포함시킬 때 포접체 형성에 대한 물과 에탄올의 영향을 살펴본 결과 물 2.0 mL과 에탄올 0.5 mL이 DHA 포접에 효과적이었다. FT-IR과 XRD로 포접체를 분석해 본 결과 DHA를 포함한 포접체가 형성되었고, SEM을 통하여 포접체와 커들란, 플루란을 이용하여 마이크로 캡슐의 형태를 살펴볼 수 있었다.

• 산업기술연구
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• 제30권A호
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• pp.37-43
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• 2010

Polymeric materials in addition to Portland cement and hydrated limes were used to solidify heavy metal contaminated tailings from five abandoned metal mines in Korea. Mine tailings were mixed separately with Portland cement and hydrated lime at a concentration of 20-30 wt% and 6-9 wt%, respectively and Ethylene Vinyl Acetate(EVA) powder was added to each specimen at a ratio of 2.5 and 5.0 wt% to binders. Polymer-added and polymer-free solidified forms were evaluated for their appropriateness in accordance with the suggested test methods. Regardless of addition of polymeric materials, all solidified forms satisfy the uniaxial compressive strength(UCS) requirements(0.35MPa) for land reclamation and show remarkably reduced leaching concentrations of heavy metals such as As, Cd, Cu, Pb and Zn less than the toxicity criteria of Korean standard leaching test(KSLT). The addition of polymeric materials increased the UCS of solidified forms to improve a long-term stability of solidified mine tailings.

• The Korean Journal of Ecology
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• 제15권3호
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• pp.267-279
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• 1992

The relationship between pb, zn, cd, and the microbial biomass and activity were investigated in three public park soils of central and outer london. Variability with distance from the roadside and profile were studied. The heavey metal concentrations were the highest in hampstead heath and hyde park with high trafic density and the lowest in hainault. The highest concentrations of heavy metals were found adjacent to the roadside in the upper parts of the soil profile. Dehydrogenase activity, adenosine tri-phosphate and ergosterol contents used as indices of micrbial biomass and activity, were generally higher in hainadult, and also higher in the upper pats of the soil profile. Simple regression analysis indicated that the microbial biomass and activity were affected significantly by moisture content, water holding capacity, total organic carbon, total nitrogen, and organic mater rather than heavy metal concentration. Highest inputs of nitrogen and carbon were associated with high inputs of heavey metals, all three being derived from vehicle emissions adjacent to the road. The hyde park and hampstead heath microbial populations were able to respond to the c and n input positively by increase in biomass and activity, whereas the hainault populations could not. This rsult suggrsts adaptation in he former to heavy matals, but not in the latter.

• Advances in environmental research
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• 제3권4호
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• pp.283-292
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• 2014

Iron precipitating organisms play a significant role in the formation of ferric hydroxide precipitate, which acts as strong adsorbent for toxic metal. In this respect four different iron precipitating cultures were isolated from Hutti gold mine surface winze water sample on citrate agar medium. The best isolate was screened out for metal removal study on the basis of fast visual iron precipitation. The selected isolate was identified as Enterobacter sp. based on routine biochemical tests and Biolog GN microplate results and as Enterobacter cloacae subsp. dissolvens by 16S rRNA gene sequence analysis (GenBank accession number EU429448). Influence of medium composition, medium initial pH, the influence of inoculum size, effect of various media and ferric ammonium citrate concentration were studied on metal removal in shake flask experiments. Under the optimized conditions studied, E. cloacae showed $94{\pm}2$, $95{\pm}2$ and $70{\pm}2%$ of cadmium, copper and mercury removal from a simulated waste in shake flask studies. In lab scale column reactor more than 85% of copper and mercury removal was achieved.