• The Korean Journal of Ecology
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• v.27 no.3
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• pp.141-146
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• 2004

This paper reports on Pb and Cd concentrations in the tissues of 76 individuals of 16 rare bird species found dead across Korea. In most of species, Pb concentration was higher in kidney and bone than in liver. The range of the mean liver Pb was 0.47 (Cygnus cygnus)∼3.74 ㎍/wet g (Asio flammeus). Based on hepatic Pb concentrations, 39 (51.3%) of the 76 individuals were classifed as background level (〈2㎍/wet g), 35 (46.1%) were elevated level (〉2㎍/wet g) and 2 (2.6%) were poisoned level (〉10㎍/wet g). These results were indicated many rare birds were suffered from chronic Pb exposure. Cd concentration was generally higher in kidney than in liver and bone. The range of the mean kidney Cd was 0.06 (Bubo bubo)∼l.75㎍/wet g (falco subbuteo). Only one of the 76 individuals had elevated Cd concentration (〉2.7㎍/wet g) in kidney. These results indicated most of rare birds had low Cd accumulations.

• Journal of Nutrition and Health
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• v.31 no.2
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• pp.126-134
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• 1998

Our previous study demonstrated that dietary taurine or glycine supplementation significantly lowered plasma and hepatic cholesterol and triglyceride concentrations in rats fed a cholesterol-free diet. In the present study, the effect of long term dietary taurine or glycine supplementation, for the purpose of preventing and/or treating of hyperlipidemia and other known biological functions, on plasma and hepatic free amino acid concentrations and profiles were evaluated in rats. Three groups of male rats(110-130g) were fed a control diet(CD), taurine-supplemented diets(TSD ; CD+ 1.5% taurine) or glycine-supplemented diet(GSD ; CD+1.5% glycine) for 5 weeks. Plasma and hepatic free amino acid concentrations were determined by an automated amino acid analyzer based on ion-exchange chormatography. The feeding of TSD for 5 weeks yielded a 444% higher plasma taurine concentration , and the feeding GSD for the same period resulted in a 143% higher plasma glycine level in rats compared to those fed DB. Hepatic taurine concentration was significantly higher in rats fed TSD(145% increase) compared to the control rats. However, hepatic glycine concentration was not influenced by dietary glycine supplementation , which implies that the massive dose of glycine entering the body was more rapidly metabolized or excreted than taurein. Dietary taurine or glycine supplementation resulted in similar changes in plasma free amino acid concentrations, except in levels of taurine and glycine. Plasma levels of histidine, lysine, phenylalanine , alanine, proline, hydroxypoline, $\alpha$-aminogutyric acid, cystathionine and ethanolamine were significantly higher in rats fed TSD or GSD than those fed GD. Glycine supplementation did not change hepatic free amino acid concentrations as compared to CD. Concentrations of most hepatic free amino acids were not influenced by dietary taurine supplementation with the exception of significantly higher levels of asparate and tyrosine(56-63% increase) and lower levels of histidine and glutamate(33-34% decrease) compared to the control rats. These results suggest long-term dietary taurine or glycine supplementation resulted in increases in most plasma free amino acid levels, but did not cause a characteristic change in plasma aminogram pattern compared to rats fed CD.

• Journal of Powder Materials
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• v.23 no.2
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• pp.91-94
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• 2016

High-quality colloidal CdSe/ZnS (core/shell) is synthesized using a continuous microreactor. The particle size of the synthesized quantum dots (QDs) is a function of the precursor flow rate; as the precursor flow rate increases, the size of the QDs decreases and the band gap energy increases. The photoluminescence properties are found to depend strongly on the flow rate of the CdSe precursor owing to the change in the core size. In addition, a gradual shift in the maximum luminescent wave (${\lambda}_{max}$) to shorter wavelengths (blue shift) is found owing to the decrease in the QD size in accordance with the quantum confinement effect. The ZnS shell decreases the surface defect concentration of CdSe. It also lowers the thermal energy dissipation by increasing the concentration of recombination. Thus, a relatively high emission and quantum yield occur because of an increase in the optical energy emitted at equal concentration. In addition, the maximum quantum yield is derived for process conditions of 0.35 ml/min and is related to the optimum thickness of the shell material.

• Journal of Powder Materials
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• v.29 no.6
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• pp.453-458
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• 2022

We successfully synthesize water-dispersible CTAB-capped CdSe@ZnS quantum dots with the crystal size of the CdSe quantum dots controlled from green to orange colors. The quenching effect of Fe(DTC)₃ is very efficient to turn off the emission light of quantum dots at four molar ratios of the CdSe quantum dots, that is, the effective covering the surface of quantum dots with Fe(DTC)₃. However, the reaction with Fe(DTC)₃ for more than 24 h is required to completely realize the quenching effect. The highly quenched quantum dots efficiently detect nitric oxide at nano-molar concentration of 110nM of NO with 34% of recovery of emission light intensity. We suggest that Fe(DTC)₃-hybridized CdSe@ZnS quantum dots are an excellent fluorescence resonance energy transfer probe for the detection of nitric oxide in biological systems.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.35.1-35.1
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• 2010

The Cu(In,Ga)Se2(CIGS) thin film solar cells have been achieved until almost 20% efficiency by NREL. These solar cells include chemically deposited CdS as buffer layer between CIGS absorber layer and ZnO window layer. Although CIGS solar cells with CdS buffer layer show excellent performance, many groups made hard efforts to overcome its disadvantages in terms of high absorption of short wavelength, Cd hazardous element. Among Cd-free candidate materials, the CIGS thin film solar cells with Zn compound buffer layer seem to be promising with 15.2%(module by showa shell K.K.), 18.6%(small area by NREL). However, few groups were successful to report high-efficiency CIGS solar cells with Zn compound buffer layer, compared to be known how to fabricate these solar cells. Each group's chemical bah deposition (CBD) condition is seriously different. It may mean that it is not fully understood to grow high quality Zn compound thin film on the CIGS using CBD. In this study, we focused to clarify growth mechanism of chemically deposited Zn compound thin film on the CIGS, especially. Additionally, we tried to characterize junction properties with unfavorable issues, that is, slow growth rate, imperfect film coverage and minimize these issues. Early works reported that film deposition rate increased with reagent concentration and film covered whole rough CIGS surface. But they did not mention well how film growth of zinc compound evolves homogeneously or heterogeneously and what kinds of defects exist within film that can cause low solar performance. We observed sufficient correlation between growth quality and concentration of NH3 as complex agent. When NH3 concentration increased, thickness of zinc compound increased with dominant heterogeneous growth for high quality film. But the large amounts of NH3 in the solution made many particles of zinc hydroxide due to hydroxide ions. The zinc hydroxides bonded weakly to the CIGS surface have been removed at rinsing after CBD.

• Korean Journal of Environmental Agriculture
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• v.26 no.3
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• pp.204-209
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• 2007

Agricultural area in the vicinity of the ${\triangle}{\triangle}$ smelting factory in Kyeongbuk province, the third largest zinc smelting factory in the world, was contaminated by high concentration of heavy metals. However, the heavy metals source was not yet directly traced and thus, resulted to a conflict between the factory and residents within its vicinity. In order to determine the level of heavy metal contamination in the arable lands located at the north eastern part of the factory, soils were sampled systematically. To find out the major reason for the occurrence of this problem, waters and aerosols were sampled with constant intervals to the upward and downward direction from the factory and were analyzed to find out the heavy metal concentrations. Cadmium (Cd) and zinc (Zn) of the heavy metals were highly accumulated more than the Korean warning criteria (Cd 1.5, Zn 300 mg $kg^{-1}$) with mean values 1.7 and 407 mg $kg^{-1}$, respectively, at the surface soils (0-20 cm), and heavy metal concentration significantly decreased with increasing soil depth In addition, the concentration of both metals slightly decreased with increasing distance from the factory to the surface soils. Cadmium and Zn were detected in the upward stream water with low concentration and concentrations increased significantly in the downstream after passing across the factory. Aerosol samples also showed traces of Cd and Zn which could be attributed to the contamination of the water system and the surface soils. Conclusively, Cd and Zn emitted from the ${\triangle}{\triangle}$ smelting factory moved with the aerosol in the atmosphere and thus, contaminated the agricultural areas and the water system within it vicinity.

• Journal of Korean Society on Water Environment
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• v.33 no.5
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• pp.556-562
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• 2017

Heavy metals in water systems are being managed on the concentration-based guidelines in Korea. However, various chemicals present in water can interact with heavy metals affecting their toxicity. Such interactions are not considered in the concentration-based guidelines. This study investigated the effect of hardness and coexisting heavy metals on heavy metal toxicity to emphasize the importance of having the effect-based guidelines together with the concentration-based guidelines in water management. The toxic effects of Cd, Zn, or mixtures of Cd and Zn were studied with Daphnia magna as a test species following the standard test method at different hardness conditions (100, 200, and $300mg\;L^{-1}$ as $CaCO_3$). The toxicities of single metal solutions and mixtures showed a decreasing trend with increasing hardness, and this can be attributed to the competition between heavy metals and cations such as calcium ions ($Ca^{2+}$) that cause hardness. The predicted toxicities of the heavy metal mixtures from the single metal toxicity deviated from the measured toxicities, and the predicted toxic effects tend to be greater than the measured toxic effects suggesting that Cd and Zn are in competition. This shows the limitations of using predicted toxic effects and the needs for further studies on mixture toxicities. Overall, this study shows that the management of heavy metals in waters needs to employ the effect-based guidelines together with the concentration-based guidelines.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 1998.05a
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• pp.37-54
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• 1998

This study was conducted to investigate the effects of mugwort extracts on the blood ethanol concentration, liver function and low level of cadmuim(Cd) in rats. The effects of mugwort extracts on the blood ethanol concentration was studied in Sprague-Dawley rats (10 weeks old) administered p.o. with 25% ethanol (5g/1kg body weight) and then injected with mugwort extracts (at the 2% levels of daily feed consumption compared with the concentration of catechins level in mugwort extracts) in caudal vein. SD rats were divided into five groups : control group (CON-E, only ethanol and 0.85% saline sol'n treated instead of each extracts), water extracts of mugwort treated to the control (MDW-E), ethanol extracts of mugwort treated to the control (POH-E). And then rat plasma of each time (0hr, 1hr, 2hr, 3hr) was investigated ethanol concentration by gas chromatography. Another rats were measured at the time of 0 and 5hr for the test of GOD(Glutamic Oxaloacetic Transaminase) and GPT(Glutamic Pyruvic Transaminase). Components of each extracts were analyzed by using high performance liquid chromatography. The effects of mugwort extracts on the liver function were studied in culture of rat hepatocyte composed of three groups : Control group and two groups treated with each extracts (1% & 2% MDW, 1% & 2% MOH). Condition of rat hepatocytes cultured for 36hr at $37^{\circ}C$(5% $CO_2$ incubator), number of cells, GOT and GPT activity were investigated. The results obtained were summarized as follows ; 1. Catechins level of mugwort extracts was $8{\sim}10mg/100g(MDW)$, $3{\sim}4mg/100g(MOH)$ 2. The contents of (-)-Epigallocatechin was high in MDW 3. The effects of mugwort extracts on the blood ethanol concentration were as follows; 1) The order in ethanol degradation efficiency was MDW-E > MOH-E > CON-E. 2) Ethanol concentration significantly decreased (p<0.05) in MDW-E and MOH-E. 4. The effects of mugwort extracts on the liver function were as follows; (rat hepatocytes cultured for 36hr at $37^{\circ}C$) 1) Cells condition of MDW-L was better than other groups. 2) The order in number of cells (rat hepatocytes) was 2% MDW-L >1% MDW-L >1% MOH-L > Con-L > 2% MOH-L 5. Cd treatment increased concentrations of hepatic GSH level, and decreased GOT activity in plasma. Therefore, this results suggest that the effects of mugwort extracts may an important rols in degradation ethanol and recovery liver function in body. Also, Mugwort extracts may modify the toxicities of Cd in Cd-treated rats and play an important roles in preventing the liver from various toxicants including Cd in Cd treated rats.

• The Korean Journal of Malacology
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• v.9 no.2
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• pp.85-93
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• 1993

Contamination of heavy metals in water and sediments along Mantyeong (river) has reached up to critical level, The object of the study is to dlucidate some macroinvertebrates which inhabit along the river in respect to the modulatory role in reducing the pollution. For the purpose, Scapharca subcrenata(sea shell) which is common in numbers and biomass in the area was collected, and cadmium (Cd) was subjected as a reference metal in the experiment. The seashell was dried and autoclaved, followed by pellet preparation under various concentration of Cd: 50,100,250,500 and 1,500 ug /pellet. Mice were fed for 3 months, althrough last group(5 mice), 1,500 ug/pellet, died within 4 weeksof the administration.MT-Cd in liver and kidney increased in correlation with the amont of Cd concentration in pellet, especially in kidney than in liver. Liver and kidney of the mice showed pathological changes such as cellular infiltration and focal necrosis in liver, and peri-tubular cell infiltration or tubular necrosis etc. The changes were more intensive by amount of the Cd. Overall results in the present study suggest that Cd may eventually combine with soluble-protein forming metalloprotein, then reduce the toxicity of heavy metal, How the formed Mt-Cd is discharged from the kidney and the mechanism shall be the further subject to be clarified.

• Nutritional Sciences
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• v.7 no.1
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• pp.3-7
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• 2004

This study was performed to investigate the effect of a raw diet (RD) on blood glucose and immune function in non-diabetic (normal) and streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were assigned to four groups (normal control, normal RD, diabetic control and diabetic RD). The control groups and the RD groups were fed an AIN-diet and RD for four weeks, respectively. Weight gain was statistically lower in the RD groups than in the controls. Fasting plasma glucose was significantly lower in the diabetic RD group than in the diabetic control group. The $CD4^+$ T-cell population was higher along with the $CD4^+/CD8^+$ ratio of the mesenteric lymph nodes in the normal RD group compared to the other groups. It can be concluded that RD may reduce the plasma fasting glucose concentration in diabetic rats and improve mesenteric lymph node immune function in normal rats.