• Journal of Korean Society of Water and Wastewater
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• v.19 no.4
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• pp.404-410
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• 2005

A series of batch type adsorption experiments were performed to remove aquatic phosphorus, where the layered double hydroxide (HTAL-CI) was used as an powdered adsorbent. It showed high adsorption capacity (T-P removal: 99.9%) in the range of pH 5.5 to 8.8 in spite of providing low adsorption characteristics (pH<4). The adsorption isotherm was approximated as a modified Langmuir type equation, where the maximum adsorption amount (50.5mg-P/g) was obtained at around 80mg-P/L of phosphorus concentration. A phosphate ion can occupy three adsorption sites with a chloride ion considering the result that 1 mol of phosphate ion adsorbed corresponded to the 3 moles of chloride ion released. Although the chloride ion at less than 1,000mg-CI/L did not significantly affect the adsorption capacity of phosphate, carbonate ion inhibited the adsorption property.

• Ocean and Polar Research
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• v.26 no.1
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• pp.43-50
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• 2004

The diffusion model, which considers diffusion and sorption, is proposed. The FEM program developed on the basis of the diffusion model provides the estimation of chloride concentration according to cyclic humidity and sorption. After the humidity diffusion analysis is carried out, the chloride ion diffusion and sorption analysis are conducted on the basis of the preestimated humidity data in each element. Each element has different analysis variables at different ages and locations. At early ages, the difference between inner and outer relative humidity causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference with age, the effect of sorption on the chloride ion penetration decreases. By the way, the cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and the quantity of chloride ion around steel at later ages. Therefore, the in situ analysis of chloride ion penetration for marine concrete structures must be performed considering the cyclic humidity condition and the long term sorption.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.114-122
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• 2000

Several new ion exchange resins have been synthesized from chloromethyl styrene-1,4-divinylbenzine with 1%, 2%, 5% and 105-crosslink and macrocyclic ligands of cryptand type by interpolymerization method. The adsorption characteristics and the pH, time, solvents and concentration dependence of the adsorption of uranium ion by this resins were studied. The resins were very stable in both acidic and basic media and have good resistance to heat at $300^{\circ}C$. The uranium ion are not adsorbed on the resins below pH 3.0, but the power of adsorption of it increased rapidly above pH 4.0. The optimum equilibrium time for adsorption of uranium ion was two hours and adsorptive power decreased in proportion to crosslink size of the resins and order of dielectric constants of solvents used and the adsorption for uranium ion was bin the order of $OdienNtn-H_4$ > $OtnNen-H_4$ > $OtnNen-H_4$ > $OenNen-H_4$.

• Nuclear Engineering and Technology
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• v.32 no.5
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• pp.504-513
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• 2000

The adsorption characteristics of methyl iodide generated from the simulated off-gas stream on various adsorbents such as silver ion-exchanged zeolite (AgX), zeocarbon and activated carbon were investigated. An extensive evaluation was made on the optimal silver ion-exchanged level for the effective removal of methyl iodide at temperature up to 38$0^{\circ}C$. The degree of adsorption efficiency of methyl iodide on silver ion-exchanged zeolite is strongly dependent of silver ion-amount and process temperature. The influence of temperature, methyl iodide concentration and silver ion-exchanged level on the adsorption efficiency is closely related to the pore characteristics of adsorbents. It would be facts that the effective silver ion-exchanged level was about 10 wt%, based on the degree of silver utilization for the removal of methyl iodide.

• Journal of Microbiology
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• v.33 no.3
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• pp.228-233
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• 1995

As S. epidermidis cell was fractionated into cell wall, cell membrane, and cytoplasm, the cell membrane proved to be the most efficient absorbent for lead ion. Utrasonication was effective, when the cells were treated during their exponential growth. The amount of the lead ion adsorbed in cell membrane decreased as hydrogen ion concentration of solution increased. Protein purified from the cell membrane showed higher adsorption capacity for the lead ion than peptidoglycan, teichoic acid from cell wall, or cell membrane lipid. Modification of carboxyl groups in the membrane protein with ethylenediamine and 1-ethyl-3-carbodiimide hydrochloride resulted in a considerable decrease of lead ion adsorption capability, suggesting that the main binding site for lead ion was the carboxyl groups of protein in cell membrane.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1246-1249
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• 1994

Thin amorphous film of $a-Se_{75}Ge_{25}$ acts as a positive resist in ion beam lithography. Previously, we reported the optical characteristics of amorphous $Se_{75}Ge_{25}$ thin film by the low-energy ion beam exposure and presented analytically calculated values such as ion range, ion concentration and ion transmission coefficient, etc. As the calculated results of analytical calculation, the energy loss per unit distance by $Ga^+$ ion is about $10^3[keV/{\mu}m]$ and nearly constant for all energy range. Especially, the projected range and struggling for 80 [KeV] $Ga^+$ ion energy are 0.0425[${\mu}m$] and 0.020[${\mu}m$], respectively. Hear, we present the results of Monte-Carlo computer simulation of Ga ion scattering, exposure and development in $a-Se_{75}Ge_{25}$ resist film for focused ion beam(FIB) lithography. Monte-Carlo method is based on the simulation of individual particles through their successive collisions with resist atoms. By the summation of the scattering events occurring in a large number N(N>10000) of simulated trajectories within the resist, the distribution for the range parameters is obtained. Also, the deposited energy density and the development pattern by a Gaussian or a rectangular ion beam exposure can be obtained.

• Journal of Radiation Protection and Research
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• v.42 no.1
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• pp.63-68
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• 2017

Background: The combined effect of the low energy electron (LEE) irradiation and $Cu^{2+}$ ion on DNA damage was investigated. Materials and Methods: Lyophilized pBR322 plasmid DNA films with various concentrations (1-15 mM) of $Cu^{2+}$ ion were independently irradiated by monochromatic LEEs with 5 eV. The types of DNA damage, single strand break (SSB) and double strand break (DSB), were separated and quantified by gel electrophoresis. Results and Discussion: Without electron irradiation, DNA damage was slightly increased with increasing Cu ion concentration via Fenton reaction. LEE-induced DNA damage, with no Cu ion, was only 6.6% via dissociative electron attachment (DEA) process. However, DNA damage was significantly increased through the combined effect of LEE-irradiation and Cu ion, except around 9 mM Cu ion. The possible pathways of DNA damage for each of these different cases were suggested. Conclusion: The combined effect of LEE-irradiation and Cu ion is likely to cause increasing dissociation after elevated transient negative ion state, resulting in the enhanced DNA damage. For the decrease of DNA damage at around 9-mM Cu ion, it is assumed to be related to the structural stabilization due to DNA inter- and intra-crosslinks via Cu ion.

• Journal of environmental and Sanitary engineering
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• v.8 no.1
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• pp.67-80
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• 1993

This survey was carried out to take the status of seawater intrusion into groundwater wells located in the eastern area of Chejudo, to get the elementary data which may evaluate the level of would-be groundwater contamination, and to perform effective the effort that will supply the clear water for the residents. The sampling sites were northeastern districts of Haengwon, Handong, and Sangdo, southeastern districts of Susan, Nansan, and Samdal, and northwestern districts, as reference, of Aewol, Keumnung, Panpo, Kosan, Shindo, and Bosung. We collected the samples from the public tap water by month, and analysed electrical conductivity, sodium(Na), potassium(K), magnesium(Mg), calcium(Ca), bicarbonate($HC0_{3^-}$), and items of the criteria as drinking water. In the northeastern districts we also added the sampling sites to survey the fluctuations of dissolved solids according to distance from seashore, including two private boreholes and one public tap water of Dukchun. The result is as follows 1) In the northeastern district, the concentration of chloride ion showed large fluctations from 40mg/l to 100mg/l, but suitable for the criteria of drinking water. It was thought that the drought influenced. 2) In the Sangdo of the northeastern districts, similar tendancy to Hangwon and Handong was showed only in the concentration of chloride ion, but different tendancy was showed in chloride-bicarbonate ratio, calcium-magnesium ratio, and sodium adsorption ratio(SAR). Considering these facts, it was not thought that seawater intruded. 3) The components of Na and Cl showed rapid slope in the northeastern districts above 3km from seashore. 4) In the northwestern districts as reference, the concentration of chloride ion fluctuated slightly according to the sampling sites and dates, and the concentration of nitrate-nitrogen in some sites exceeded the criteria of drinking water. These were thought that the surface contaminants rather than the intrusion of seawater influenced mainly the groundwater, considering the correlation(r=0.732) of chloride ion and nitrate-nitrogen. 5) Then we must consider the regional characteristies of soil profile in order to prevent the contamination of groundwater, and moniter also the movement of main components within the sol1 profile, not only the research of the intrusion of seawater.

• Journal of Environmental Science International
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• v.5 no.2
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• pp.141-152
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• 1996

This study is an attempt to investigate the chemical components of precipitation and its variation according to surface wind. Precipitation samples were collected by an wet-only precipitation sampler during the period of October 1994 to September 1995 at Kyungsan in Korea. The results obtained in t체s study are summerized as follows. The annual average of precipitation pH is 5.0, the highest month of pH is July of 5.5, and the lowest month of pH is December of 4.4. The most frequent appearance is in the range of pH 5.0 to 5.5 and its rate is 56.8%, The order of ion concentration In precipitation is SO42->NO3->Cl- in case of anion and $Ca^{2+}$>$NH_4^{+}$>$Na^+$>$Mg^{2+}$ in case of cation. It is found from our analysis that the correlation coefficient among the precipitation pH and ion components is below r=0.3, while the correlation coefficient between $SO_4^{2-}$ and NO_3^{-}$, $Na^+$ and $Cl^+$ is above r=0.8, respectively. The mean pH of precipitation is 4.8 under the westerly wind and 5.2 under the easterly wind. The concentrations of anion and cation under the westerly wind are more than the concentrations under the easterly wind. In autumn, the concentration of Na+ and $Cl^+$ under the easterly wind are higher than the concentration under the westerly wind. The correlation coefficients between wind speed and pH, ion components show very low correlation of -0.41 r 0.2. But the present study show that the correlation coefficient between wind speed and pH of precipitation is positive and the correlation coefficients between wind speed and ion concentration is negative.

• BMB Reports
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• v.31 no.1
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• pp.25-30
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• 1998

Kinetic studies of L-Alanine dehydrogenase from Bacillus subtilis-catalyzed reactions in the presence of $Zn^{2+}$ were carried out. The substrate (L-alanine) saturation curve is hyperbolic in the absence of the metal ion but it becomes sigmoidal when $Zn^{2+}$ is added to the reaction mixture indicating the positive cooperative binding of the substrate in the presence of zinc ion. The cooperativity of substrate binding depends on the xinc ion concentration: the Hill coefficients ($n_H$) varied from 1.0 to 1.95 when the zinc ion concentration varied from 0 to $60\;{\mu}m$. The inhibition of AlaDH by $Zn^{2+}$ is reversible and noncompetitive with respect to $NAD^+$ ($K_i\;=\;5.28{\times}10^{-5}\;M$). $Zn^{2+}$ itself binds to AlaDH with positive cooperativity and the cooperativity is independent of substrate concentration. The Hill coefficients of substrate biding in the presence of $Zn^{2+}$ are not affected by the enzyme concentration indicating that $Zn^{2+}$ binding does not change the polymerization-depolymerization equilibria of the enzyme. Among other metal ions, $Zn^{2+}$ appears to be a specific reversible inhibitor inducing conformational change through the intersubunit interaction. These results indicate that $Zn^{2+}$ is an allosteric competitive inhibitor and substrate being a non-cooperative per se, excludes the $Zn^{2+}$ from its binding site and thus exhibits positive cooperativity. The allosteric mechanism of AlaDh from Bacillus subtilis is consistent with both MWC and Koshland's allosteric model.