• Journal of Korean Society for Quality Management
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• v.36 no.4
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• pp.93-101
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• 2008

The rare metals, used for semiconductors, PDP-LCS and other specialized metal areas necessarily, has been playing a key role for the Korean economic development. Rare metals are influenced by exogenous variables, such as production quantity, price and supplied areas. Nowadays the supply base of rare metals is threatened by the sudden increase in price. For the stable supply of rare metals, a rational demand outlook is needed. In this study, focusing on the domestic demand for chromium, the uncertainty and probability materializing from demand and price is analyzed, further, a demand forecast model, which takes into account various exogenous variables, is suggested, differing from the previously static model. Also, through the OOS(out-of-sampling) method, comparing to the preexistence ARIMA model, ARMAX model, multiple regression analysis model and ECM(Error Correction Mode) model, we will verify the superiority of suggested model in this study.

• BMB Reports
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• v.28 no.4
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• pp.311-315
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• 1995

Exogenous $Cu^{2+}$ or $Zn^{2+}$ at micromolar concentration had a strong inhibitory effect on detergent-solubilized cytochrome c oxidase. A similar effect was observed when $Cu^{2+}$ was added to vesicular cytochrome c oxidase, although the extent of inhibition was significantly larger for the uncoupled state than for the coupled state. Interestingly, the inhibition by $Zn^{2+}$ was almost negligible for both the coupled and uncoupled states. These results suggest that the binding sites for $Cu^{2+}$ ions are exposed to the extravesicular side. whereas those for $Zn^{2+}$ are exposed to the matrix side. The EPR spectra of bound $Cu^{2+}$ ions at 77 K indicate that each of the first two $Cu^{2+}$ ions is ligated by three or four histidine residues, as evidenced by distinct $^{14}N$ superhyperfine splitting. These $Cu^{2+}$ ions can not be removed readily by EDTA and inhibit the enzyme activity by as much as 80%.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_4
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• pp.189-196
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• 2001

The blue green alga, Microcystis aeruginosa, was found to accumulate proline under the stressful concentration of cupric ions. The changes of proline level in Microcystis aeruginosa in response to copper(Cu) have been monitored and the function of the accumulated proline was studied with respect to its effect on Cu uptake. Exposure of Microcystis aeruginosa elevated concentrations of Cu led to accumulation of fee proline depending on the concentrations of the metal in the external medium. The greater the toxicity or accumulation of the metal, the higher the amount of proline in algal cells were found. When proline was exogenously supplied prior to Cu treatment, the absorption of Cu was markedly reduced. When exogenous proline was supplied after Cu treatment, it resulted in a remarkable desorption of the adsorbed Cu immediately after the addition of proline. Pretreatment of Microcystis aeruginosa with proline counteracted with metal-induced lipid peroxidation. The results of the present study showed a protective elect of proline on metal toxicity through inhibition of lipid peroxidation and suggested that the accumulation of proline may be related to the tolerance mechanism for dealing with Cu stress.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.323-329
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• 2018

In Escherichia coli, the transcription of genes related to metal homeostasis is activated by the presence of target metals. The promoter regions of those genes can be fused with reporter genes to generate whole-cell bioreporters (WCBs); these organisms sense the presence of target metals through reporter gene expression. However, the limited number of available promoters for sensing domains restricts the number of WCB targets. In this study, we have demonstrated an alternative method to generate novel WCBs, based on the notion that since the sensing mechanisms of WCBs are related to metal transportation systems, their properties can be modulated by disrupting metal homeostasis. Mutant E. coli strains were generated by deleting the znt-operon genes zntA, which encodes a zinc-export protein, and zntR, which encodes a znt-operon regulatory protein, to investigate the effects on the metal-sensing properties of WCBs. Deletion of zntA increased the sensitivity but abolished the selectivity of cadmium-sensing WCBs, whereas arsenic-sensing WCBs gained sensitivity toward cadmium. When zntR was deleted, cadmium-sensing WCBs lost the ability to detect cadmium, and this was recovered by introducing exogenous zntR. In addition, the metal-binding site of ZntR was genetically engineered to modulate metal selectivity. This study provides a valuable platform for the development of novel E. coli-based WCBs.

• Environmental and Resource Economics Review
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• v.11 no.1
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• pp.121-144
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• 2002

The purpose of this study is to test pollution-heaven hypothesis on the korean pollution-intensive industries, that is, textile and clothing, petrochemical and primary metal industry. The empirical study examines that foreign direct investment(FDI) of korean pollution-intensive industries regresses on couple of exogenous variables and the environmental regulation on FDI. As the environmental regulation is not directly observed, it uses $CO_2$ emissions as the pollutant. The results of the study show that the environmental regulation in a host country is an insignificant determinant of FDI for the korean polluting industries. That is, they do not support Leonard (1988), Xing and Kolstad (2000) that the hypothesis is a significant for heavily polluting industries.

• Proceedings of the Korean Society of Crop Science Conference
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• 2023.04a
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• pp.105-105
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• 2023

Heavy metals, including lead (Pb) toxicity, are increasing in soil and are considered toxic in small amounts. Pb contamination is mainly caused by industrialization - smelting, mining. Agricultural practices - sewage sludge, pests and urban practices - lead paint. It can seriously damage and threaten crop growth. Pb can adversely affect plant growth and development by affecting the photosystem, cell membrane integrity, and excessive production of reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂)andsuperoxide(O₂.-). NO is produced via enzymatic and non-enzymatic antioxidants to scavenge ROS and lipid peroxidation substrates in terms of protecting cells from oxidative damage. Thus, NO improves ion homeostasis and confers resistance to metal stress. Our results here suggest that exogenous NO may aid in better growth under lead stress. These enhancements may be aided by NO's ability in sensing, signaling and stress tolerance in plants under heavy metal stress in combination with lead stress. Our results show that GSNO has a positive effect on soybean seedling growth in response to axillary pressure and that NO supplementation helps to reduce chlorophyll maturation and relative water content in leaves and roots following strong burst under lead stress. GSNO supplementation (200 µM and 100 µM) reduced compaction and approximated oxidative damage of MDA, proline and H₂O₂. Under plant tension, a distorted appearance was found in the relief of oxidative damage by ROS scavenging by GSNO application. In summary, modulation of these NO, PCS and prolongation of metal past reversing GSNO application confirms the detoxification of ROS induced by toxic metal rates in soybean. In summary, these NO, PCS and metal traditionally sustained rates of reverse GSNO application confirm the detoxification of ROS induced by toxic metal rates in soybean.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.1
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• pp.40-43
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• 2000

Pyrrolidinedithiocarbamate (PDTC) and N-Acetylcysteine (NAC) are metal and nonmetal-chelating antioxidant which can induce rat and human smooth muscle cell death. When the smooth muscle cells from mouse aorta (MASMC) that we successfully cultured recently was exposed to PDTC and NAC in a normal serum state, the cells were induced to death by these compounds. However, PDTC did not induce the cell death in a serum depleted medium. This data suggests that certain factors in the serum may mediate the cytotoxic effect of PDTC. The metal chelator, Ca-EDTA blocked PDTC-induced cell death, but Cu-, Fe-, and Zn-EDTA did not block the PDTC-induced cell death. This data indicated that copper, iron, and zinc in the serum may lead to the cytotoxic effect of PDTC. Investigation of the intracellular zinc level in PDTC-induced smooth muscle cell death using the zinc probe dye N-(6-methoxy-8-quinolyl)-p-toluenesulfonamide shows that only the muscle-containing layers of the arteries have higher level of zinc. As expected, PDTC increased the intracellular fluorescence level of the zinc. In agreement with these results, the addition of an exogenous metal, zinc, induced the vascular aortic smooth muscle cell death which led to an increased intracellular zinc level. We concluded that PDTC induced mouse aortic smooth muscle cell death required not only zinc level but also intracellular copper and iron level. The mechanism of this antioxidant to induce vascular smooth muscle cell death may provide a new strategy to prevent their proliferation in arteriosclerotic lesions.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.318-324
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• 1998

A ${\beta}$-galactosidase with high transgalactosylic activity was purified from a Bacillus species, registered as KFCC10855. The enzyme preparation showed a single protein band corresponding to a molecular mass of 150 kDa on SDS-PAGE and gave a single peak with the estimated molecular mass of 250 kDa on Sephacryl S-300 gel filtration, suggesting that the enzyme is a homodimeric protein. The amino acid and sugar analyses revealed that the enzyme is a glycoprotein, containing 19.2 weight percent of sugar moieties, and is much more abundant in hydrophilic amino acid residues than in hydrophobic residues, the mole ratio being about 2:1. The pI and optimum pH were determined to be 5.0 and 6.0, respectively. Having a temperature optimum at $70^{\circ}C$ for the hydrolysis of lactose, the enzyme showed good thermal stability. The activity of the enzyme preparation was markedly increased by the presence of exogenous Mg (II) and was decreased by the addition of EDTA. Among the metal ions examined, the most severely inhibitory effect was seen with Ag (I) and Hg (II). Further, results of protein modification by various chemical reagents implied that 1 cysteine, 1 histidine, and 2 methionine residues occur in certain critical sites of the enzyme, most likely including the active site. Enzyme kinetic parameters, measured for both hydrolysis and transgalactosylation of lactose, indicated that the enzyme has an excellent catalytic efficiency for formation of the transgalactosylic products in reaction mixtures containing high concentrations of the substrate.

• Korean Journal of Microbiology
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• v.48 no.3
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• pp.187-191
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• 2012

Two-component system (TCS)-based bacterial zinc and copper biosensors, in which green fluorescent protein (GFP) is expressed under the control of zraP and cusC promoter in ZraS/R and CusS/R TCS, were evaluated in artificial wastewater. Bacterial biosensors developed in this study efficiently expressed GFP by the recognition of $Zn^{2+}$ and $Cu^{2+}$ in artificial wastewater. Secondly, TCS-based zinc and copper removing bacteria with the peptide displayed on cell surface were examined in artificial wastewater. Zinc and copper removing bacteria expressed the peptide as a fusion protein such as OmpC-ZBP (zinc binding peptide) and OmpC-CBP (copper binding peptide) on the cell surface when sensing exogenous $Zn^{2+}$ and $Cu^{2+}$ through ZraS/R and CusS/R TCS. The recombinant cell expressing metal-adsorbing peptide could efficiently remove copper and zinc (15 and 18 mg/g dry cell weight, respectively) in artificial wastewater. Therefore, it was demonstrated that the TCS-based recombinant cell for the recognition or removal of heavy metal functions well in artificial wastewater environment.

• Tuberculosis and Respiratory Diseases
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• v.45 no.6
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• pp.1265-1276
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• 1998

Background : Nitric oxide(NO) is an endogenously produced free radical that plays an important role in regulating vascular tone, inhibition of platelet aggregation and white blood cell adhesion to endothelial cells, and host defense against infection. The highly reactive nature of NO with oxygen radicals suggests that it may either promote or reduce oxidant-induced cell injury in several biological pathways. Oxidant injury and interactions between pulmonary vascular endothelium and leukocytes are important in the pathogenesis of acute lung injury, including acute respiratory distress syndrome(ARDS). In ARDS, therapeutic administration of NO is a clinical condition providing exogenous NO in oxidant-induced endothelial injury. The role of exogenous NO from NO donor or the suppression of endogenous NO production was evaluated in oxidant-induced endothelial injury. Method : The oxidant injury in cultured rat lung microvascular endothelial cells(RLMVC) was induced by hydrogen peroxide generated from glucose oxidase(GO). Cell injury was evaluated by $^{51}$chromium($^{51}Cr$) release technique. NO donor, such as S-nitroso-N-acetylpenicillamine(SNAP) or sodium nitroprusside(SNP), was added to the endothelial cells as a source of exogenous NO. Endogenous production of NO was suppressed with N-monomethyl-L-arginine(L-NMMA) which is an NO synthase inhibitor. L-NMMA was also used in increased endogenous NO production induced by combined stimulation with interferon-$\gamma$(INF-$\gamma$), tumor necrosis factor-$\alpha$(TNF-$\alpha$), and lipopolysaccharide(LPS). NO generation from NO donor or from the endothelial cells was evaluated by measuring nitrite concentration. Result : $^{51}Cr$ release was $8.7{\pm}0.5%$ in GO 5 mU/ml, $14.4{\pm}2.9%$ in GO 10 mU/ml, $32.3{\pm}2.9%$ in GO 15 mU/ml, $55.5{\pm}0.3%$ in GO 20 mU/ml and $67.8{\pm}0.9%$ in GO 30 mU/ml ; it was significantly increased in GO 15 mU/ml or higher concentrations when compared with $9.6{\pm}0.7%$ in control(p < 0.05; n=6). L-NMMA(0.5 mM) did not affect the $^{51}Cr$ release by GO. Nitrite concentration was increased to $3.9{\pm}0.3\;{\mu}M$ in culture media of RLMVC treated with INF-$\gamma$ (500 U/ml), TNF-$\alpha$(150 U/ml) and LPS($1\;{\mu}g/ml$) for 24 hours ; it was significantly suppressed by the addition of L-NMMA. The presence of L-NMMA did not affect $^{51}Cr$ release induced by GO in RLMVC pretreated with INF-$\gamma$, TNF-$\alpha$ and LPS. The increase of $^{51}Cr$ release with GO(20 mU/ml) was prevented completely by adding 100 ${\mu}M$ SNAP. But the add of SNP, potassium ferrocyanate or potassium ferricyanate did not protect the oxidant injury. Nitrite accumulation was $23{\pm}1.0\;{\mu}M$ from 100 ${\mu}M$ SNAP at 4 hours in phenol red free Hanks' balanced salt solution. But nitrite was not detectable from SNP upto 1 mM The presence of SNAP did not affect the time dependent generation of hydrogen peroxide by GO in phenol red free Hanks' balanced salt solution. Conclusion : Hydrogen peroxide generated by GO causes oxidant injury in RLMVC. Exogenous NO from NO donor prevents oxidant injury, and the protective effect may be related to the ability to release NO. These results suggest that the exogenous NO may be protective on oxidant injury to the endothelium.