• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.23-24
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• 2006

We have synthesized electroluminescence materials. including [2-(2-hydroxyphenyl)benzoxazole] (Zn(HPB)$_2$), [(2-(2-hydroxyphenyl)benzoxazole)(8-hydoxyquinoline)] (Zn(HPB)q) and [(1, 10-phenanthroline)(8-hydroxyquinoline)] Zn(phen)q. The ionization potential (IP) and electron affinity (EA) of each Zn-complex was measured using cyclic-voltammetry (C-V). Basing on the consideration of matched in the energy levels of the materials. We investigated the electron transporting properties of Zn(HPB)q and Zn(phen)q compared with $Alq_3$, and also we investigated the hole blocking properties of Zn(HPB)$_2$, compared with BCP. As a result, we used Zn-complex to enhance the performance of OLED. Therefore, we demonstrate that Zn(HPB)q and Zn(phen)q are useful as an electron transporting material. Zn(HPB)$_2$ is also good a hole blocking material.

• Proceedings of the Korean Biophysical Society Conference
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• 1999.06a
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• pp.44-44
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• 1999

Yeast cytochrome c peroxidase (CcP) was cloned and overexpressed in E. coli, and purified by a Ni$^{2＋}$-affinity column. HoloCcP was obtained by reconstituting apoCcP with Mn$^{3+}$-protoporphyrin IX (MnPP). Electron paramagnetic resonance (EPR) spectra of spin-labeled holoCcP showed a slightly more immobilized signal than spin-labeled apoCcP.(omitted)

• Textile Coloration and Finishing
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• v.22 no.1
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• pp.1-7
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• 2010

The five new red disperse dyes for unmodified pure polypropylene fibers were synthesized. As a coupling component, a di-n-hexyl substituent was used in common, while various substituents were used for the diazo component. The dye having electron donating group at diazo component showed hypsochromic shift compared to the unsubstituted dye, while the dyes having electron withdrawing groups showed bathochromic shift. Owing to their extreme hydrophobicity caused by the di-n-hexyl substituent, all dyes exhibited very high affinity toward pure polypropylene fibers. Fastness to washing was very good for all dyes and fastness to light was good except two purplish red dyes.

• Journal of Life Science
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• v.9 no.1
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• pp.45-49
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• 1999

Seaweed alginate was acetylated by activated carbon immobilized Pseudomonas syringae in a fluidized bed, up-flow reactor. The acetylation degree of seaweed alginate was about 30%. Calcium-acetylated seaweed alginate gel bead was made and compared to calcium-seaweed alginate gel bead by the scanning electron microscopy (SEM). Structural difference of two gel beads may results from increased viscosity and decreased affinity of acetylated seaweed alginate for calcium ion. On the basis of interior and exterior structure of calcium-acetylated seaweed alginate gels and property of acetylated seaweed alginate, it seems that acetylated seaweed alginate is used for the supporter for electrophoresis and packing materials for liquid chromatography and gel filtration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.154-157
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• 2005

The use of electron-beam(E-Beam) manufacture systems provides a means to alleviate optic exposure equipment's problems. We designed an E-beam manufacture system with SEM function. Optimal beam scanning is one of the most important conditions in the performance of E-beam and SEM. The performance of E-beam manufacture system and images of SEM are a close affinity with each other. Developed E-beam manufacture system consist of the controllers of high voltage, scanning, optic and high voltage generator. In this paper, we analyze the condition of steady beam scanning and describe the development of controller fer optimal beam scanning.

• Bulletin of the Korean Chemical Society
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• v.19 no.2
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• pp.160-164
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• 1998

The NADH-cytochrome b5 reductase (NCBR), a mitochondrial external electron carrier, was purified from bovine heart and turnip and their properties were examined. The mitochondrial outer membranes separated were subjected to NCBR isolation through DEAE-Cellulose ion exchange, DEAE-Sephadex gel chromatography, and hydroxyapatite adsorption chromatography. These processes yielded the purification folds of 88 and 42 and the recovery percentages of 0.2%, 5.67% for turnip and bovine heart, respectively. The molecular weight of the NCBR from the two sources was estimated to be 35,000 using SDS polyacrylamide gel electrophoresis. The Michaelis constant Km and maximum velocity Vmax were determined by measuring the NADH-ferricyanide redox system as well as the NADPH-ferricyanide redox system. The kinetics showed that both NCBRs had higher affinities for NADH than artificial electron-acceptor substrate ferricyanide. Although NADPH had a lower affinity for the enzymes than NADH, this study showed the 2'-phosphate dinucleotide could be used as a substrate.

• BMB Reports
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• v.31 no.4
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• pp.307-327
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• 1998

Cytochrome c peroxidase (CcP) is a yeast mitochondrial enzyme which catalyzes the reduction of hydrogen peroxide to water using two equivalents of ferrocytochrome c. The CcP/cytochrome c system has many features which make it a very useful model for detailed investigation of heme protein structure/function relationships including activation of hydrogen peroxide, protein-protein interactions, and long-range electron transfer. Both CcP and cytochrome c are single heme, single subunit proteins of modest size. High-resolution crystallographic structures of both proteins, of one-to-one complexes of the two proteins, and a number of active-site mutants are available. Site-directed mutagenesis studies indicate that the distal histidine in CcP is primarily responsible for rapid utilization of hydrogen peroxide implying significantly different properties of the distal histidine in the peroxidases compared to the globins. CcP and cytochrome c bind to form a dynamic one-to-one complex. The binding is largely electrostatic in nature with a small, unfavorable enthalpy of binding and a large positive entropy change upon complex formation. The cytochrome c-binding site on CcP has been mapped in solution by measuring the binding affinities between cytochrome c and a number of CcP surface mutations. The binding site for cytochrome c in solution is consistent with the crystallographic structure of the one-to-one complex. Evidence for the involvement of a second, low-affinity cytochrome c-binding site on CcP in long-range electron transfer between the two proteins is reviewed.

• Nano
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• v.13 no.10
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• pp.1850116.1-1850116.14
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• 2018

In this study, we report the mercury ions ($Hg^{2+}$) mediated phosphorus-containing carbon dots (PCDs) as a selective "off-on" fluorescence probe for glutathione (GSH), cysteine (Cys) and homocysteine (Hcys). PCDs obtained by hydrothermal reaction are sensitive to $Hg^{2+}$ ions and its fluorescence can be significantly quenched owing to the electron transfer from the lowest unoccupied molecular orbital (LUMO) of PCDs to $Hg^{2+}$. Interestingly, the weak fluorescence of $Hg^{2+}$-mediated PCDs could be gradually recovered with the addition of GSH, Cys and Hcys. This can be attributed to the formation of $Hg^{2+}-S$ complex due to the super affinity of $Hg^{2+}$-sulfydryl bond. The formation of $Hg^{2+}-S$ complex extremely reduces the oxidation ability of $Hg^{2+}$ that inhibits the electron transfer from LUMO of PCDs to $Hg^{2+}$ and re-opens the native electron transition from LUMO to the highest occupied molecular orbital (HOMO) of PCDs. Thus, the green fluorescence of PCDs is switched on. Furthermore, the present $Hg^{2+}$-mediated PCDs assay exhibits a high selectivity for GSH, Cys and Hcy and has been successfully used to detect the total biothiols content in human urine samples.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.743-748
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• 2010

Boron nitride (BN) and carbon nitride (CN) films, which have relatively low work functions and commonly exhibit negative electron affinity behaviors, were coated on carbon nanotubes (CNTs) by magnetron sputtering. The CNTs were directly grown on metal-tip (tungsten, approximately 500nm in diameter at the summit part) substrates by inductively coupled plasma-chemical vapor deposition (ICP-CVD). The variations in the morphology and microstructure of CNTs due to coating of the BN and CN films were analyzed by field-emission scanning electron microscopy (FE-SEM). The energy dispersive x-ray (EDX) spectroscopy and Raman spectroscopy were used to identify the existence of the coated layers (CN and BN) on CNTs. The electron-emission properties of the BN-coated and CN-coated CNT-emitters were characterized using a high-vacuum field emission measurement system, in terms of their maximum emission currents ($I_{max}$) at 1kV and turn-on voltage ($V_{on}$) for approaching $1{\mu}A$. The results showed that the $I_{max}$ current was significantly increased and the $V_{on}$ voltage were remarkably reduced by the coating of CN or BN films. The measured values of $I_{max}-V_{on}$ were as follows; $176{\mu}A$-500V for the 5nm CN-coated emitter and $289{\mu}A$-540V for the 2nm BN-coated emitter, respectively, while the $I_{max}-V_{on}$ of the as-grown (i.e., uncoated) emitter was $134{\mu}A$-620V. In addition, the CNT emitters coated with thin CN or BN films also showed much better long-term (up to 25h) stability behaviors in electron emission, as compared with the conventional CNT emitter.

• Journal of the Korean Chemical Society
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• v.41 no.3
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• pp.117-122
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• 1997

On the basis of our previous paper[Bull. Korean Chem. Soc. 1995, 16, 1015], the relative stability, ionization potential, and chemical reaction of the neutral and multiply charged $C_{60}$n ions(n=3+ to 6-) have been investigated by the semi-empirical MNDO method. $C_{60}^{1-}$ has the highest stability. The ionization potential values of the $C_{60}$ ions range from 15.31 eV of $C_{60}^{2+}$ to -13.01 eV of $C_{60}^{6-}$. These values show a linear relationship according to charges. The average IP per charge is 3.15 eV from our calculations and 3.22 eV from the linear function of IP. A charge- or electron-transfer reaction of $C_{60}^{n+}$ will only occur if the ionization potential of any guest molecule is lower than the electron affinity of the host $C_{60}^{n+}$. If the energy gap between ionization potential and electron affinity, ${\Delta}_{IP-EA}$, is high, charge-transfer reactions arise by the charge-controlled effect. However, if ${\Delta}_{IP-EA}$ is low, electron-transfer reactions arise by the frontier-controlled effect.