• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.1995-2000
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• 1989

The ion beam system of 20keV C-W (Cockroft Walton) type composed of the AuGe alloy LMIS(Liquid Metal Ion Source) has been designed and constructed. For the fabrication of the ohmic contact to the n-GaAs, the ion beam extracted from the AuGe alloy source was implanted into the n-GaAs, and it was measured by contact resistivity. The stable AuGe ion beam(2.5\ulcorner/cm\ulcorner was obtained at the extraction voltage of 14.5kV. The measurements of the contact resistivity were done by the TLM (Transmission Line Model) method and the specific contact resistivity was found to be 2.4x10**-5 \ulcornercm\ulcornerfor the implanted sample by the 1.9x10**20/cm**3 and the annealed sample at 30\ulcorner for 2 min.

• Journal of environmental and Sanitary engineering
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• v.14 no.3
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• pp.63-70
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• 1999

A study on the zeolite synthesized of bituminous coal fly ash from power plant has been carried out to reuse industrial waste. The synthesized zeolite was proved to be 4A type by means of the X-ray diffraction analysis and the degree of crystallinity was found to be higher than 90%. Then the synthesized zeolite was used as an adsorbent to remove the heavy metal ions in the CU, Pb, and Cd containing wastewater and water. Also, adsorption characteristics and kinetics of synthesized zeolite in the each metal ion solutions were studied. In each ion solutions, the adsorbed amounts of Pb, Cd, and Cu to the unit weight of synthesized zeolite were 141.6, 118.8, and 131.4mg/g respectively when each metal ion concentration was 500mg/L solution. The adsorption kinetics was fitted well to the Freundlich isotherms. The value of l/n for Pb, Cd, and Cu and 0.27, 0.50, and 0.66, respectively. Those results showed that the synthesized zeolite could be used as an adsorbent to remove single heavy metal ions in the wastewater and water. The heats of adsorption, H values of Pb, Cd, and Cu were 4.87, 14.95, and 18.23kacl/mol by the Henry-van't Hoff equation.

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2201-2206
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• 2010

To improve the separation property and stability of metal chelate Cu(II) column, three new kinds of multidentate aminocarboxy silica columns with cation-exchange properties were synthesized using glutamic acid (Glu), glutamic acidbromoacetic acid (Glu-BAA), glutamic acid-bromosuccinic acid (Glu-BSUA) as ligands and silica gel as matrix. The standard proteins were separated with prepared chromatographic columns. The stationary phases exhibited the metal chelate property after fixing copper ion (II) on the synthesized multidentate ligand silica columns. The binding capacity of immobilized metal ion was related with the dentate number of multidentate ligands. Chromatographic behavior of proteins and the leakage of immobilized metal ion on multidentate chelate Cu(II) columns were affected by the dentate number of multidentate ligands and competitive elution system directly. The results showed that quinquedentate Glu-BSUA-Cu(II) column exhibited better chromatographic property and stability as compared with tridentate Glu-Cu(II) column, tetradentate Glu-BAA-Cu(II) column and commonly used IDA-Cu(II) column.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.156-171
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• 1992

Chitin was isolated from crab shell. Chitosan, which was prepared by the deacetylation of chitin, was acylated to obtain N-acetyl(regenerated chitin), N-propionyl, N-butyryl, N-hexanoyl, N-decanoyl and N-maleated chitosans and their metal ion adsorption characteristics of N-acylchitosans were investigated. In order to enhance the adsorptivity, their porous beads were prepared and their adsorptivity with respect to the porosity and the adsorptivities for metal ions($Cu^{2+}$, $Ni^{2+}$, $CO^{2+}$, $Mn^{2+}$, $Ag^{+}$)were investigated. Their metal ion adsorptivities were remarkably imporved compared to those of chitin. As the larger acyl groups were introduced, adsorptivity increased, but that of N-decanoyl chitosan showed some decrease because of steric hindrance of the bulky N-decanoyl group. N-Maleated chitosan containing carboxyl group showed highly improved adsorptivity, and N-acylchitosans showed the good selective adsorption in the mixed metal ions($Cu^{2+}$, $Ni^{2+}$, $CO^{2+}$, $Mn^{2+}$ and $Ag^{+}$). They also showed excellent adsorption characteristics as chelating polymers.

• Bulletin of the Korean Chemical Society
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• v.21 no.4
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• pp.393-400
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• 2000

2,2￠-Dihydroxyazobenzene (DHAB) was attached to poly(ethylenimine) (PEI) to obtain DHAB-PEI. Spectral titration revealed that uranyl, Fe(III), Cu(II), and Zn(II) ion form 1 : 1-type complexes with DHAB attached to PEI. Formation constants for the metal complexes formed by the DHAB moieties of DHAB-PEI were mea-sured by using various competing ligands. The results indicated thatthe concentrations of uranyl, Fe(III), and Cu(II) ions can be reduced to 10 -16 -10 -23 M at p 8 with DHAB-PEI when the concentration of the DHAB moiety is 1 residue M. By using cyanuric chloride as the coupling reagent, DHAB-PEI was immobilized on Sephadex G-25 resin to obtain DHAB-PEI-Seph. Binding of uranyl,Fe(III), Cu(II), and Zn(II) ion by DHAB-PEI-Seph was characterized by using competing ligands. A new method has been developed for characteriza-tion of metal sequestering ability of a chelating resin. Formation constants and metal-binding capacity of two sets of binding sites on the resin were estimated for each metal ion. DHAB-PI-Seph was applied to recovery of metals such as uranium,Fe, Cu, Zn, Pb, V, Mn, and W from seawater. The uranium recovery from seawaterby DHAB-PEI-Seph does not meet the criterion for economical feasibility partlydue to interference by Fe and Zn ions. The seawater used in the experiment was contaminated by Fe and Zn and, therefore, the efficiency of uranium extractionfrom seawater with DHAB-PEI-Seph could be improved if the experiment is carried out in a cleaner sea.

• Membrane Journal
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• v.29 no.3
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• pp.123-129
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• 2019

Environmental pollution caused by the presence of heavy metal ion from growing industrialization or from leaching is increasing area of concern. There are several area of water purifications but among them adsorption on the functionalized polymer fibers is efficient and cost-effective method. Polyacrylonitrile (PAN) is exciting polymer due to the presence of excessive functional group which can be easily transformed for metal ion adsorption. PAN can be easily electrospun to prepare nanofiber that have higher surface area leading to better metal ion removal. Composite PAN fiber is yet another type of polymer covered in this review for waste water treatment.

• Textile Coloration and Finishing
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• v.18 no.1
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• pp.10-19
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• 2006

Despite several recent attempts to measure the concentration of individual catechins by HPLC, it has not been so easy to separate catechins accurately. The aim of the present work is to provide a proper condition for separating each component of catechins by HPLC analysis, and also to evaluate the experimental variables including color differences, and metal ion contents after dyeing and mordanting. Four kinds of Catechins, (-)-epicatechin(EC), (-)-epicatechin gallate(ECG), (-)-epigallocatechin(EgC), (-)-epigallocatechin gllate(EgCG) were isolated from the residues after dyeing. Catechins in Korean green tea leaves are richer when e tea leaves are younger. Higher concentration of catechins owes it to e way it is processed. The contents of catechins adsorbed in silk fabrics after dyeing were in order of EGCG>ECG>EGC>EC. We have found $68\%$ uptake of EGCG, and 116.8mg of EGCG in the silk fabrics after it was dyed with $1\%$ Korean green tea extracts. The absorbance intensity and K/S values of dyed silk fabrics were increased with dyeing temperature and time. Only the surface color of the silk fabric dyed with green tea extracts was yellowish red, but it changed from yellowish red to red with an increase in the mordant concentration. Post-mordanted silk fabrics with ferrous sulfate changed from yellowish red to red and purple color shade. In a practical evaluation, there is no significant change in color after twenty times of the continuous dry cleaning process. However, post-mordanted fabrics with ferrous sulfate faded the brightness of color after dry cleaning. Dyeing silk fabrics with a Korean tea extract reduced the metal ion contents in the silk fabrics when compared to the untreated silk fabrics. Metal contents in silk fabrics dyed and post-mordanted with $1\%$ each metal solution were 0.194 ppm for Aluminum, 1.601ppm for Copper, and 0.334 ppm for Iron. After the post-mordanting process, the heavy metal ion absorption increased, which was mainly attributed to the catechins and polyphenols in dyed silk fabrics.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.218-224
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• 1999

Continuous ion exchange characteristics of the synthetic coolant contained Ni, Co and Ag ions of low concentration in acidic-oxidizing conditions have been studied to suggest the guideline for the optimum operation of mixed-bed demincralizer during the shutdown period of a pressurized water reactor (PWR). In the effect of the form of cation resins on the removal capacity of metal ions, the performance of a $H^+$-form resin was about 6% higher than that of a $Li^+$-form resin. Mixed-bed of cation and anion resins in comparison with nonmixed-bed of them, had no affected on the removal capacity of metal ions but very slightly increased the slope of breakthrough curves of metal ions. In the effect related to acidic-oxidizing conditions of the coolant, the addition of boric acid very slightly decreased the slope of breakthrough curves of metal ions, while the addition of hydrogen peroxide slightly decreased the removal capacity of metal ions.

• Biomolecules & Therapeutics
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• v.10 no.4
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• pp.293-302
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• 2002

The classical concept for iron uptake into mammalian cells has been the endocytosis of transferrin( $T_{f}$ )-bound F $e^{3+}$ via the $T_{f}$ - $T_{f}$ receptor cycle. In this case, we could not explain the uptake of F $e^{2＋}$ ion and the export of iron from endosome. Studies on iron transport revealed that other transport system exists in epithelial cells of the intestine. One of non- $T_{f}$ -receptor-mediated transport systems is Nramp2/DMT1/DCT1 which transports M $n^{＋＋}$, $Mg^{＋＋}$, Z $n^{＋＋}$, $Co^{＋＋}$, N $i^{＋＋}$ or C $u^{＋＋}$ ion as well as F $e^{+2}$ ion. DMT1 was cloned from intestines of iron-deficient rats and shown to be a hydrogen ion-coupled iron transporter and a protein regulated by absorbed dietary iron. DMT1 is founded in other cells such as cortical and hippocampal glial cells as well as endothelial cells in duodenum. Two F $e^{3+}$ ion bound to transferrin( $T_{f}$ ) are taken up via the $T_{f}$ - $T_{f}$ receptor cycle in the intestinal epithelial cell. F $e^{3+}$ in endosome was converted to F $e^{2＋}$ ion, and then exported to cytosol via DMT1. F $e^{2＋}$ ion is taken up into cytosol via DMT1. Several other transporters such as FET, FRE, CCC2, AFT1, SMF, FTR, ZER, ZIP, ZnT and CTR have been reported recently and dysfunction of the transporters are related with diseases containing Wilson's disease, Menkes disease and hemochromatosis. Evidences from several studies strongly suggest that DMT1 is the major transporter of iron in the intestine and functions critically in transport of other metal ions.

• Korean Journal of Environmental Agriculture
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• v.7 no.2
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• pp.96-101
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• 1988

It is important to assess the effects of ionic strength and type of anions when studying the adsorption of heavy metals on zeolite because the background salt may complex with heavy metals and compete for adsorption sites. This experiment was carried out to determine the effect of ionic strength and anion species($Cl^-$, $SO^{2-}\;_4$, and $ClO^-\;_4$) on heavy metal adsorption. Heavy metal adsorption by zeolite from solutions in the range of 10 to 50ppm was studied in the presence of NaCl, $Na_2SO_4$ and $NaClO_4$, with different concentrations. The ionic strength ranged from 0.01 to 1.00. Adsorption of heavy metal cations could be described by the Freundlich isotherm equation. Increasing the ionic strength of equilibrium solutions, the amounts of heavy metal adsorbed on the zeolite surfaces decreased in all three of the anion systems. This fact could be attributed to the competition of background salt cation and the decrease in initial activity of heavy metal cations. In the presence of Cl anion, less adsorption resulted than in the presence of $SO_4$ or $ClO_4$ anions of the same ionic strength, indicating the presence of uncharged and negatively charged complexes of heavy metal with Cl ligands.