• Journal of environmental and Sanitary engineering
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• v.20 no.3 s.57
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• pp.27-35
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• 2005

The ion exchange resins have been synthesized from chlormethyl styrene - 1,4 -divinyl-benzene(DVB) with $1\%,\;4\%,\;and\;10\%$-crosslinking and macrocyclic ligand of cryptand type by copolymerization method and the adsorption characteristics of uranium(VI), calcium(II) and lutetium(III) metallic ions have been investigated in various experimental conditions. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of metallic ions were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium $(UO_2^{2+})>calcium(Ca^{2+})>lutetium(Lu^{3+})$ ion. The adsorption was order of $1\%,\;4\%,\;and\;10\%$ crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.31-32
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• 2011

Granulated slag from metal industries and fly ash from the combustion of coal are industrial by-products that have been widely used as mineral admixtures in normal and high strength concrete. Due to the reaction between calcium hydroxide and fly ash or slag, the hydration of concrete containing fly ash or slag is much more complex compared with that of Portland cement. In this paper, the production of calcium hydroxide in cement hydration and its consumption in the reaction of mineral admixtures is considered in order to develop a numerical model that simulates the hydration of concrete containing fly ash or slag. The heat evolution rates of fly ash- or slag-blended concrete is determined by the contribution of both cement hydration and the reaction of the mineral admixtures. Furthermore, the temperature distribution and temperature history in hardening blended concrete are evaluated based on the degree of hydration of the cement and the mineral admixtures. The proposed model is verified through experimental data on concrete with different water-to-cement ratios and mineral admixture substitution ratios.

• Parasites, Hosts and Diseases
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• v.41 no.3
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• pp.165-169
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• 2003

This study describes the characterization of 80 kDa pretense showing gelationlytic property among three pretenses in the excretory/secretory proteins (ESP) from Toxoplasma gondii. The pretense activity was detected in the ESP but not in the somatic extract of RH tachyzoites. This pretense was active only in the presence of calcium ion but not other divalent cationic ions such as $Cu^{2+},{\;}Zn^{2+},{\;}Mg^{2+},{\;}and{\;}$Mn^{2+}$, implying that $Ca^{2+}$ is critical factor for the activation of the protease. The 80 kDa pretense was optimally active at pH 7.5. Its gelatinolytic activity was maximal at $37^{\circ}C$, and significant level of enzyme activity of the pretense remained after heat treatment at $56^{\circ}C$ for 30 min or $100^{\circ}C$ for 10 min, This thermostable enzyme was strongly inhibited by metal chelators, i.e., EDTA, EGTA, and 11 10-phenanthroline. Thus, the 80 kDa pretense in the ESP secreted by T. gondii was classified as a calcium dependent neutral metalloprotease.

• Journal of Environmental Health Sciences
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• v.8 no.1
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• pp.55-60
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• 1982

This study was carried out in order to clarify the combined effect of cadmium and lead on rat bones when exposed to single metal (1 mg cd/kg body weight) and cambined metals (1 mg cd + 4 mg pb/kg body weight). Seventy five mature rats of Sprague-Dawley species were divided into a control group and a treatment group that were administered by daily peritoneum injection for 7 to 9 weeds, and their body weights were measured every week. The results were summarized as follows 1. Body weight gains of the combined injection group and the single injection groups were lower than that of the control group. 2. In case of the combined injection group, the amount of cadmium accumulated in femur was more than that of the cadmium group. These amounts of cadmium accumulated showed an increasing trend. 3. The lead amount in bone tissue of the combined injection group presented also an increasing trend. In this case, the additive action of cadmium to the lead accumulation in bone tissue was conspicuous. 4. The amounts of calcium and phosphorus in femur showed clear a decreasing trend in the cadmium group and combined administration group. The ratio of calcium and phosphorus (ca/p) in the cadmium group was not different from that of the control group, but in the combined injection group the ratio was a little lower.

• Journal of Environmental Science International
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• v.9 no.1
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• pp.43-47
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• 2000

A study on the remediation of heavily for ion contaminated soils from abandoned iron mine was carried out, using ex-situ extraction process. Also, oxalic acid as a complex agent was evaluated as a function of concentration, reaction time and mixing ratio of washing agent in order to evaluate Fe removability of the soil contaminated from the abandoned iron mine. Oxalic acid showed a better extraction performance than 0.1N-HCl, i.e., the concentrations of Fe ion extracted from the abandoned mine for the former at uncontrolled pH and the latter were 1,750 ppm and 1,079 ppm, respectively. The optimum washing condition of oxalic acid was in the ratio of 1:5 and 1:10 between soil and acid solution during l hr reaction. The total concentrations of Fe ion by oxalic acid and EDTA at three repeated extraction, were 4,554 ppm and 864 ppm, respectively. The recovery of Fe ions from washing solution was achieved, forming hydroxide precipitation and metal sulfide under excess of calcium hydroxide and sodium sulfide. In addition, the amounted of sodium sulfide and calcium hydroxide for the optimal revovery of Fe were 15g/$\ell$ and 5g/$\ell$ from the oxalic acid complexes, respectively.

• Journal of Microbiology
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• v.43 no.3
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• pp.237-243
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• 2005

The protease purified from Bacillus cereus JH108 has the function of leucine specific endopeptidase. When measured by hydrolysis of synthetic substrate (N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide), the enzyme activity exhibited optimal activity at pH 9.0, $60^{\circ}C$. The endopeptidase activity was stimulated by $Ca^{++},\;Co^{++},\;Mn^{++},\;Mg^{++},\;and\;Ni^{++}$, and was inhibited by metal chelating agents such as EDTA, 1,10-phenanthroline, and EGTA. Addition of serine protease inhibitor, PMSF, resulted in the elimination of the activity. The endopeptidase activity was fully recovered from the inhibition of EDTA by the addition of 1 mM $Ca^{++}$, and was partially restored by $Co^{++}\;and\;Mn^{++}$, indicating that the enzyme was stabilized and activated by divalent cations and has a serine residue at the active site. Addition of $Ca^{++}$ increased the pH and heat stability of endopeptidase activity. These results show that endopeptidase requires calcium ions for activity and/or stability. A Lineweaver-Burk plot analysis indicated that the $K_m$ value of endopeptidase is 0.315 mM and $V_{max}$ is 0.222 ) is $0.222\;{\mu}mol$ of N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide per min. Bestatin was shown to act as a competitive inhibitor to the endopeptidase activity.

• The Korean Journal of Zoology
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• v.30 no.2
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• pp.107-116
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• 1987

It is the purpose to investigate the physiological toxity and mutagenicity by heavy metal compounds such as potasium dichromate, sodium arsenite and selenium dioxide on the development of Drosophila melanogaster. These chemical compounds were highly toxic at every developmental stage of Drosophila. The relative values of fecundity, viability and developmental time obtained on food media containing 5 different levels of potasium dichromate (500, 600, 700, 800, and 900 ppm), also 5 different levels of sodium arsenite and selenium dioxide (10, 15, 20, 25 and 30 ppm). Resulting in the relative values of fecundity and viability generally decreased, on the contrary developmental time generally reduced as the concentration of chemicals in the food increased. A significant reduction in the fecundity was observed between 800 and 900 ppm (p<0. 01) on the potasium dichromate media, between 15 and 20 ppm (p<0. 05) on the sodium arsenite media, between 20 and 25 ppm (p<0. 02) on the selenium dioxide media. A significant reduction in the viability was observed between 700 and 800 ppm (p<0. 01) on the potasium dioxide media, between 25 and 30 ppm (p<0. 01) on the sodium arsenite media, between 20 and 25 ppm (p<0. 01) on the selenium dioxide media. The developmental time was significantly reduced between 800 and 900 ppm (p<0. 001) on the potasium dioxide media, between 15 and 20 ppm (p<0. 001) on the sodium arsenite media, and between 25 and 30 ppm (p<0. 01) on the selenium dioxide media.

• Journal of Applied Biological Chemistry
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• v.61 no.4
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• pp.367-370
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• 2018

Lysozyme is an antibacterial enzyme that is found in most of body fluids. Lysozyme in tears plays a primary role in protecting eye from harmful environments; if lysozyme is degraded or inhibited, eyes are likely to be more vulnerable to bacterial infection. In this study, lysozyme activity was evaluated according to varying concentrations of heavy metals, copper, zinc, cobalt and manganese and light metal, calcium that are frequently found in airborne particulate matters and was assayed using a dye-quenching lysozyme substrate, Micrococcus lysodeikticus. Less fluorescence intensity was observed with increasing amounts of copper, zinc, manganese and cobalt but not with calcium suggesting that these metals have some affinity with lysozyme and inhibit lysozyme activity. When albumin, the second most common protein in tears, was added on the reaction of lysozyme and metals, lysozyme activity was partially restored. This finding suggests that the albumin might protect damage caused by metals on lysozyme. To identify whether the decrease in enzymatic activity was related to structural changes of lysozyme, SDS-PAGE was conducted and only with copper did lysozyme show marked smearing bands on the SDS-gel, meaning that copper degraded lysozyme consistent with the sharpest activity decrease.

• Progress in Superconductivity
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• v.4 no.1
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• pp.10-13
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• 2002

We report the effect of Ca doping in $YBa_2Cu_3O_{7-\delta}$ (YBCO) thin films grown on the Rolling- Assisted, Biaxially Textured Substrates (RABiTS) with the architecture of $CeO_2/YSZ/CeO_2/Ni$. Critical currents of bilayer and trilayer structures of $YBCO/Y_{0.7}Ca_{0.3}Ba_2Cu_3O_{7-\delta}$/(YCaBCO) as well as undoped YBCO for comparison have been measured in a wide range of temperatures and fields. For $6-8^{\circ}$ grain boundaries, 30% Ca-doping in bilayer structure enhances $J_c$ as high as 35%. The enhancement is larger at low temperatures and at magnetic fields. On the other hand, 30% Ca-doping in trilayer structure reduces $J_c$ as high as 60%. Combined with slightly lower $T_c$, this indicates that Ca is overdoped in this structure and degrades GBs.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.38-44
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• 2003

This study was performed to investigate the levels of fluoride (F), calcium (Ca), and magnesium (Mg) in water samples taken from five reservoirs or direct sources on a stream used for agricultural or domestic water in the Iksan and Wanjoo areas, Jeon-buk, Korea, and to find a possible link between Ca or Mg and fluoride in water sources in theses areas. The samples were collected by the recommendation methods of the World Health Organization and analyzed by the recommendations of the Japanese Standard Methods. Statistical analyses were performed by the analysis of variance and correlation analysis. The F levels in water samples wire 0.80~2.53 ppm. In four sampling sites the water fluoride levels exceeded 1 ppm. which if the recommended level for fluorosis/caries control. The Ca levels in water samples were 6.82~12.98 ppm, and the Mg levels were 0.30~1.97 ppm, which are lower compared with the natural levels of water sources previously reported by other investigators. This study showed a positive correlation between Ca and Mg (r= 0.8779. p<0.01) and a negative correlation between F and Ca (r=-0.6974, p<0.05) and also between F and Mg (r=-0.5581) in the water samples. However, the study did not find remarkable relationships in fluoride levels between sampling sites. These results support the fact that there were epidemics of dental fluorosis in this area. The lack of significant positive correlations in fluoride levels between sampling sites suggests that there may be some pathways for the transfer of the metal to the water through other environmental media besides the water course. Long-term epidemiological studies are needed on the relationship between high F together with low Ca and Mg levels in the water, and total human health in this community. There should alto be a long-term monitoring of the water quality in this area.