• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.345-353
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• 1983

The polyurethane foam impregnated with 5, 7-dibromo-8-hydroxyquinoline (DBHQ) has been studied to be applied to the quantitative adsorption and recovery of Hg(II) from the aqueous solutions. The adsorption of Hg(II) by DBHQ-OPP foam is due to the chelation between DBHQ-OPP foam and Hg(II) on the foam, forming each colored insoluble chelate with 1:2 mole ratio. The optimum experimental conditions for the adsorption of Hg(II) has been determined. The quantitative recovery of Hg(II) adsorption by the OPP foam and reuse of DBHQ-OPP foam were investigated. Hypothesis on the adsorption and separation mechanism of Hg(II) and DBHQ to the polyurethane foam was proposed.

• Journal of Microbiology and Biotechnology
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• v.3 no.3
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• pp.161-167
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• 1993

Immobilized metal ion affinity chromatography (IMAC) was used to separate various types of recombinant hirudins from the culture broth. The wild type hirudin exhibited a retention in Cu(II)-chelated affinity chromatgoraphy since it contained a single exposed histidine at position 51. To obtain a stronger retention on an IDA-Cu(II) column, the hirudin variants were genetically engineered to contain one or two histidine (s) more than the wild type. While the affinity of the variants for IDA-Cu(II) ligand increased in comparison to that of the wild type, the antithrombin activities reduced to a certain degree. Cu(II), Ni(II) and Zn(II) ions were applied separately to the metal chelate column to investigate ligand specificity with respect to protein retention. As a result, the Cu(II) chelated chromatography gave the best resolution for all the hirudins tested and appeared to be the only IMAC that could be used generally for the purification of hirudins with a decreasing pH gradient.

• Bulletin of the Korean Chemical Society
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• v.15 no.5
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• pp.364-368
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• 1994

Growth inhibition potency of the anthraquinones, anthraquinone-1,5-disulfonic acid and carminic acid, for Sarcoma 180 and L1210 leukemia cells in vivo and in vitro, was induced by the divalent transition metal ion, $Cu^{2+}$. On the other hand spectroscopic titration data show that the anthraquinone drugs form $Cu2^+$ chelate complexes (carminic acid : $Cu^{2+}$ = 1 : 6; anthraquinone-1,5-disulfonic acid : $Cu^{2+}$ = 1 : 3). Furthermore the $Cu^{2+}$-drug complexes associate with DNA to form the $Cu^{2+}$-anthraquinone-DNA ternary complexes. The formation of the complexes was further supported by the $H_2O_2-dependent$ DNA degradation, which can be inhibited by ethidium bromide, caused by the $Cu^{2+}$-drug complexes. It is likely that the $Cu^{2+}$-mediated cytotoxicity of the anthraquinone drugs is related with the $Cu^{2+}-mediated$ binding of the anthraquinone drugs to DNA and DNA degradation.

• Journal of Electrochemical Science and Technology
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• v.13 no.1
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• pp.100-111
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• 2022

This paper presents a simple and inexpensive method to fabricate chemically and mechanically resistant hot electron-emitting composite electrodes on reusable substrates. In this study, the hot electron emitting composite electrodes were manufactured by doping a polymer, nylon 6,6, with few different brands of carbon particles (graphite, carbon black) and by coating metal substrates with the aforementioned composite ink layers with different carbon-polymer mass fractions. The optimal mass fractions in these composite layers allowed to fabricate composite electrodes that can inject hot electrons into aqueous electrolyte solutions and clearly generate hot electron- induced electrochemiluminescence (HECL). An aromatic terbium (III) chelate was used as a probe that is known not to be excited on the basis of traditional electrochemistry but to be efficiently electrically excited in the presence of hydrated electrons and during injection of hot electrons into aqueous solution. Thus, the presence of hot, pre-hydrated or hydrated electrons at the close vicinity of the composite electrode surface were monitored by HECL. The study shows that the extreme pH conditions could not damage the present composite electrodes. These low-cost, simplified and robust composite electrodes thus demonstrate that they can be used in HECL bioaffinity assays and other applications of hot electron electrochemistry.

• Analytical Science and Technology
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• v.5 no.4
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• pp.389-399
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• 1992

Liquid Chromatographic behavior of Pd(II) in Isonitrosoethylacetoacetate lmine, $Pd(IEAA-NR)_2$ (R=H, $CH_3$, $C_2H_5$, $n-C_3H_7$, $C_6H_5-CH_2$, $n-C_4H_9$) chelates were investigated by reversed-phase HPLC on Micropak MCH-5 column using methanol/water as mobile phase. The optimum conditions for the separation of $Pd(IEAA-NR)_2$ chelates were examined with respect to the effect of the flow rate, sample solvent, mobile phase strength and column temperature. It wass found that metal chelates were properly eluted in an acceptable range of capacity factor value($0{\leq}log\;k^{\prime}{\leq}1$). The dependence of the logarithm of capacity factor(k') on the volume fraction of water in the binary mobile phase was examined. Also, the dependence of k' on the liquid-liquid extration distribution ratio($D_c$) in methanol-water/n-alkane extration system was investigated. Both kinds of dependence are linear, which susggests that the retention of the electroneutral metal chelate is largely due to the solvophobic effect. Standard adsorption enthalpy changes (${\Delta}H^{\circ}$) and standard adsorption entropy changes (${\Delta}S^{\circ}$) of Pd(II) Isonitrosoethylacetoacetate imine chelates on Micropak MCH-5 column were calculated by measuring capacity factor with changing temperature of the column.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.189-197
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• 1994

Analytic methods for Cr(VI) level in industrial hygienic field were suggested by the National Institute for Occupational Safety and Health(NIOSH method 7600, 7604). There were growing needs for measurement of Cr(III) and Cr(VI) levels simultaneously. Two analytical methods were suggested to determine Cr(III) and Cr(VI) levels simultaneously. The one is method by using reversed phase high peformance liquid chromatography(HPLC) and the other is by using ion exchange HPLC. The purpose of this work was to evaluate the usefulness of these two analytic methods. For the difference of ionic charges of Cr(III)-ethylendiamine tetraacetic acid(EDTA) chelate and $CrO_4{^-2}$, we could detect them simultaneously by ion exchange HPLC. Also, we attempted to determine the levels of Cr(III) and Cr(VI) chelated with sodium diethyldithiocarbamate(NaDDTC) by using reversed phase HPLC. The confirmation of Cr(III) and Cr(VI) were checked by fraction collector and nameless atomic absorption spectrometer. The optimal conditions for the formation of Cr(III)-EDTA chelate were two hours incubation period with pH 5. Cr(III)-EDTA and Cr(VI) in EDTA solution were successfully separated by anion exchange column using $Na_2CO_3/NaOH$ mixture as mobile phase. Peaks of Cr(III)-EDTA and Cr(VI) in EDTA were identified at 5 minutes and 7 minutes of retention time respectively by the ion exchange HPLC. The formation of Cr(III)-NaDDTC and Cr(VI)-NaDDTC chelates were twelve hours incubation period. Cr(III)-NaDDTC and Cr(VI)-NaDDTC chelates were separated by reversed phase column using methanol and water mixture as mobile phase. Peaks of Cr(VI)NaDDTC and Cr(III)-NaDDTC chelates were identified at 13 minutes and 26 minutes of retention time respectively by the reversed phase HPLC. Due to reduction of Cr(VI) to Cr(III), it seems to be not suitable for simultaneous determination of Cr(III)-NaDDTC and Cr(VI)-NaDDTC chelates by reversed phase HPLS. Simultaneos determination of Cr(III) and Cr(VI) by ion exchange HPLC was more accurate and simple method.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.767-772
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• 2011

The purpose of this study was to find out required time for recovery of nutritional disorder by Fe-DTPA treatment in induced Fe-deficient tomato cultivars and to select stable Fe-chelate in high pH of nutrient solution. The pH levels of nutrient solution were amended with 6.0, 7.0, and 8.0. Then Fe-EDTA (Ethylenediaminetetraacetic acid, ferric-sodium salt), Fe-DTPA (Sodium ferric diethylenetriamine pentaacetate), and Fe-EDDHA (Ethylenediamine-N,N-bis (2-hydroxyphenylacetic acid) ferric-sodium salt)) were treated as Fe $2.0mg\;L^{-1}$ concentration. The Fe-DTPA and Fe-EDDHA were stable in the nutrient solution of pH 6.0~8.0 but Fe-EDTA in nutrient solution of pH 8.0 was to become insoluble by 25%. The Fe $2.0mg\;L^{-1}$ as Fe-DTPA was treated for recovery of Fe deficient tomato seedlings. In case of Redyoyo and Supersunroad cultivars, total chlorophyll and Fe contents of leaves were recovered as much as those of normal leaves in 5 days. The Rafito cultivar for complete recovery was taken 7 days. When Fe $2.0mg\;L^{-1}$ as Fe-DTPA was supplied to Fe-deficient tomato seedlings, in geotype, heme oxigenase recovered as much as normal leaves in 24 hours in the Rafito and Redyoyo. However, it was not remarkable difference by elapsed time in the Supersunroad.

• Korean Journal of Crystallography
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• v.16 no.2
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• pp.128-137
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• 2005

We report on the phase transitions of the perovskite nanostructures made by sol-gel template synthesis. The lead titanate ($PbTiO_{3}$) nanostructures were prepared with a chelate sol-gel of titanium tetrabutoxide ($Ti(O^{i}Pr){4}$) and lead acetate ($Pb(OAc)_{2}-3H_{2}O$). $Whatman^{\circledr}$ anodisc membranes (with about 200 nm pore size) served as the template. The template was dipped into the sol, allowed to air dry, and then calcined at $650^{\circ}C$. We have characterized the temperatures of the phase transitions in the $PbTiO_{3}$ nano-structures using DSC, DTA, and second harmonic generation (SHG).

• Analytical Science and Technology
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• v.12 no.5
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• pp.387-396
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• 1999

The retention behavior of Cot(II)-dithiocarbamate(DTC) chelates in reversed phase high performance liquid chromatography was investigated. Enthalpy and entropy of chelates transfer from the mobile phase to the stationary phase were calculated from retention data using van't Hoff plots. The dependence of In k' on enthalpy was decreased with increasing organic solvent ratio on the mobile phase. The compensation temperatures(${\beta}$) calculated from the slope of $-{\Delta}H^0$ vs In k' were in the range of 756.3-888.5 K. From these results. it was found that the retention mechanism of DTC chelates was invariant under the various temperatures and was largely affected by the solvophobie effect. Liniear relationship between S index and log k' in emprical retention equation, $log\;k^{\prime}=log\;{k_w}^{\prime}-S_{\varphi}$ showed that S index was influenced mainly by the interaction between DTC chelates and the mobile phase.

• Analytical Science and Technology
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• v.12 no.5
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• pp.397-402
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• 1999

The open-chain hexadentate $N_6$, ligand containing two pyridyl groups, 1,15-bis(2-pyridyl)-2,6,10,14-tetraazapentadecane (bpyped) has been synthesized as its tetrahydroehloride salt and characterized by EA, IR, NMR, and Mass. Its proton dissociation constants($logK{^n}_H$) and stability constants ($log\;K_{ML}$) for Co(II), Ni(II), Cu(II) and Zn(II) ions were determined at $25^{\circ}C$ and ionic strength 0.10 M($KNO_3$) in aqueous solution by potentiometry and compared with those or analogous $N_6$ ligands contain one or two propylenic spacers, which make six-membered chelate rings, between the aliphatic nitrogen atoms.