• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.930-937
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• 2007

Korean pine(Pinus densiflora) bark was evaluated for its adsorption capacity of Cu(II) ions from aqueous solution by running a series of batch experiments. Prior to the tests, the milled barks were treated with 1 N NaOH or 1 N HCl to examine the effect of surface modification. For comparison, untreated bark was tested under same condition. Within the tested pH range between 3 and 6, NaOH treatment increased Cu(II) adsorption capacity by $139\sim184%$, while HCl treatment decreased it by $37\sim42%$. Maximum copper ion uptake by bark was observed at pH $5\sim6$, but pH of solution was not a potent influence. A pseudo second-order kinetic model fitted well for the sorption of copper ion onto bark. For NaOH-treated bark, the calculated sorption capacity$(q_e)$ increased from 6.58 to 12.77 mg/g, while the equilibrium rate constant$(k_2)$ decreased from 0.284 to 0.014 g/mg/min as initial Cu(II) concentration doubled from 100 mg/L. A batch isotherm test using NaOH-treated bark showed that equilibrium sorption data were represented by both the Langmuir model and the Freundlich model. It was confirmed that carboxylic acid of bark was involved in the Cu(II) adsorption. For NaOH-treated bark, in particular, carboxylate ion produced by hydrolysis or saponification appeared to be a major functional roup responsible for the enhanced Cu(II) sorption.

• Journal of Information Display
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• v.3 no.1
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• pp.17-21
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• 2002

Measurement of the ion-induced secondary electron emission coefficient (${\gamma}_i$) for insulating films is hampered by an unavoidable charging problem. Here, we demonstrate that a pulsed ion beam technique is a viable solution to the problem, allowing for accurate measurement of ${\gamma}_i$ for insulating materials. To test the feasibility of the pulsed ion beam method, the secondary electron emission coefficient from n-Si(100) is measured and compared with the result from the conventional continuous beam method. It is found that the ${\gamma}_i$ from n-Si(100) by the ion pulsed beam measured to be 0.34, which is the same as that obtained by continuous ion beam. However, for the 1000 A $SiO_2$ films thermally deposited on Si substrate, the measurement of ${\gamma}_i$ could be carred out by the pulsed ion method, even though the continuous beam method faced charging problem. Thus, the pulsed ion beam is regarded to be one of the most suitable methods for measuring secondary electron coefficient for the surface of insulator materials without experiencing charging problem. In this report, the dependence of ${\gamma}_i$ on the kinetic energy of $He^+$ is presented for 1000 ${\AA}$ $SiO_2$ films. And the secondary electron emission coefficient of 1000 ${\AA}$ MgO e-beam-evaporated on $SiO_2/Si$ is obtained using the pulsing method for $He^+$ and $Ar^+$ with energy ranging from 50 to 200 eV, and then compared with those from the conventional continuous method.

• Bulletin of the Korean Chemical Society
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• v.24 no.4
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• pp.489-493
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• 2003

2-Mercaptobenzothiazole was used as a highly selective and efficient carrier for the uphill transport of silver ion through a chloroform bulk liquid membrane. In the presence of thiosulfate ion as a suitable metal ion acceptor in the receiving phase, the amount of silver transported across the liquid membrane after 180 min was 90 ± 3.0%. The selectivity and efficiency of silver ion transported from aqueous solutions containing equimolar mixtures of $Zn^{2+}, Cu^{2+}, Co^{2+}, Ni^{2+}, Cd^{2+}, Pb^{2+}, Bi^{3+}, Fe^{2+}, Fe^{3+}, Pd^{2+}, Mn^{2+}, Hg^{2+}, Sn^{2+}, Ca^{2+}, Mg^{2+}, K^+, Na^+ and Li^+$ were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.157-161
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• 2000

Blue phosphor of Ba-Mg-Al-O:Eu$^{2+}$ phase was fabricated by conventional firing techniques under reducing atmosphere and its photoluminescence properties are studied with varying Eu concentration and phost-annealing temperature under air atmosphere. This phosphors were well crystallized with particle size in the range of 3~5um and emitted a blue light at a dominent wavelength 450nm for 254nm UV irradiation. The concentration quenching wit Eu$^{2+}$ was that with increasing Eu concentration the energy transfer between the activator ions steadily improves, so that the excitation energy is transported over larger distances through the lattice before luminescence can occur. Thermal quenching also occurred in this phosphor means that in a host lattice with the $\beta$-alumina structure the bond of an Eu$^{2+}$ ion with the nearest-neighbour oxygen ion is much stronger than in a lattice with the magnetoplumbite structure.cture.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.817-821
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• 2001

A new $Mg_{2-x}MN_xSnO_4$ phosphor with an inverse spinel structure was synthesized by the solid-state reaction technique. The photoluminescence properties of the $Mg_2SnO_4$:Mn phosphors were investigated under 147nm -vacuum ultraviolet ray excitation. The Mn-doped $Mg_2SnO_4$ phosphor exhibited high emission intensity with the spectrum centered at 500nm wavelength. It was explained that the green emission in $Mg_2SnO_4$:Mn phosphor has originated from energy transfer from $^4T_1$ to $^6A_1$ of $Mn^{2+}$ ion at tetrahedral site of the spinel structure. The $Mn^{2+}$ ion concentration exhibiting the maximum emission intensity under the excitation of 147nm-vacuum ultraviolet ray was 0.25mol%. And the decay time of the phosphor was shorter than 10ms.

• Applied Microscopy
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• v.34 no.2
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• pp.95-102
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• 2004

The TEM samples prepared by ion milling have the advantage that thin area can be obtained from almost any materials. However, it has the disadvantage that the amount of thin area can often be quite limited. For the cross-sectioned samples and grossly heterogeneous materials, the thickness of less than $0.1{\mu}m$ can be achieved by mechanical grinding and polishing (tripod polisher) and then the TEM samples may be ion-milled for final thinning or cleaning. These approaches were described in this paper. Examples of TEM observations were taken from cross-section samples of thin films on silicon and sapphire, from diffusion layers between $Mo_5Si_3\;and\;Mo_2B$, and from rapidly solidified 304 stainless steel powders embedded in electroplated copper.

• Analytical Science and Technology
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• v.17 no.2
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• pp.91-97
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• 2004

Cryptand ion exchange resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene (DVB) copolymer with crosslink of 1%, 2%, 5% and 10% by substitution reaction. 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 uranium ($UO{_2}^{2+}$) ion 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 ($UO{_2}^{2+}$), magnesium ($Mg^{2+}$), neodymium ($Nd^{3+}$) ion. The adsorption was in order of 1%, 2%, 5%, and 10% crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.325-330
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• 2000

The hydroxyapatite (HAp) for the present study was prepared by precipitation method in semiconductor fabrication and the crystallized at ambient to 95$0^{\circ}C$ for 30min in electric furnace. The ion-exchange characteristics of HAp for various heavy metal ions such as $Cd^{2+}, Cu^{2+}, Mn^{2+}, Zn^{2+}, Fe^{2+}, Pb^{2+}, Al^{3+}, and Cr^{6+}$ in aqueous solution has been investigated. The removal ratio of various metal ions for HAp were investigated with regard to reaction time, concentration of standard solution, amount of HAp and pH of solution. The order of the ions exchanged amount was as follws: $Pb^{2+}, Fe^{3+}>Cu^{2+}>Zn^{2+}>Al^{3+}>Cd^{2+}>Mn^{2+}>Cr^{6+}. The Pb^{2+}$ ion was readily removed by the Hap, even in the strongly acidic region. The maximum amount of the ion-exchange equilibrium for $Pb^{2+}$ ion was about 45 mg/gram of HAp. The HAp would seem to be possible agent for the removal of heavy metal ions in waste water by recycling of waste sludge in semiconductor fabrication.

• Archives of Pharmacal Research
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• v.26 no.10
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• pp.826-831
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• 2003

ADP-ribose pyrophosphatase (ADPRase) hydrolyzes ADP-ribose (ADPR) into AMP and ribose-5'-phosphate. It is classified into two groups, $Mg^{2+}$-dependent and $Mg^{2+}$-independent ADPRase, depending on its $Mg^{2+}$requirement. Here, we purified $Mg^{2+}$-dependent ADPRase from rabbit liver and examined what factors affect $Mg^{2+}$ requirement. The purified enzyme showed a single band with the molecular weight of 34 kDa on SDS-PAGE both in the presence and absence of 2-mercaptoethanol. The molecular weight of the native enzyme calculated by gel filtration was 68 kDa, indicating that ADPRase is a dimer made up of two identical subunits. $Mg^{2+}$-dependent ADPRase with the highest ADPR affinity had a $K_m$ of 160$\pm$10 $\mu$M and a pH optimum of around pH 9.5. Treatment of the purified ADPRase with heated cytosol fractions at 37$^{\circ}C$ for 3 h caused some changes in the chemical properties of the enzyme, including an increase in molecular weight, a decrease in solubility, and a loss of $Mg^{2+}$-dependency. The molecular weight of the cytosol-treated ADPRase measured by gel filtration was over 420 kDa, suggesting, for the first time, that ADPRase could be polymerized by undefined cytoplasmic factors, and that polymerization is accompanied by changes in the solubility and metal ion dependency of the enzyme.

• Journal of Environmental Science International
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• v.23 no.12
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• pp.2129-2134
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• 2014

The antioxidant activities and total phenolics of four Rosaceae species Pourthiaea villosa (Thunb.) Decne, Sorbus commixta Hedlund, Sorbaria sorbifolia var. stellipila Maxim and Pyrus pyrifolia (Burm.f.) Nakai were determined. Phenolic content (polyphenol and flavonoid), radical scavenging activities [2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylnezthiazoline-6-sulfoic acid) (ABTS)] and ferrous ion chelating effect were evaluated. Total polyphenol and flavonoid contents were highest in Pourthiaea villosa (Thunb.) Decne and lowest in Pyrus pyrifolia (Burm.f.) Nakai. Phenolic contents of Pourthiaea villosa (Thunb.) Decne was $331.45{\pm}7.78$ and $90.4{\pm}3.5mg{\cdot}g^{-1}$. DPPH and ABTS radical scavenging activities were found to be lowest in Sorbus commixta Hedlund whereas Sorbaria sorbifolia var. stellipila Maxim and Pourthiaea villosa (Thunb.) Decne showed relatively good DPPH and ABTS radical scavenging activities. Ferrous ion chelating effect was highest in Pyrus pyrifolia (Burm.f.) Nakai ($1.05{\pm}0.04mg{\cdot}ml^{-1}$) and lowest in Sorbus commixta Hundlund ($4.22{\pm}0.71mg{\cdot}ml^{-1}$).