• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.473-482
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• 2012

A novel malemide epoxy containing Co(II), Ni(II) and Cu(II) ions have been synthesized by curing malemide epoxy resin (MIEB-13) and Co(II), Ni(II) and Cu(II) complexes of macrocyclic bis-hydrazone Schiff base. The Schiff base was synthesized by reacting 1,4-dicarbnyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol. The Schiff base and its Co(II), Ni(II) and Cu(II) complexes have been characterized by elemental analyses, spectral (IR, $^1H$ NMR, UV-vis., FAB mass, ESR), thermal and magnetic data. The curing reaction of maleimide epoxy compound with metal complexes was studied as curing agents. The stability of cured samples was studied by thermo-gravimetric analyses and which have excellent chemical (acid/alkali/solvent) and water absorption resistance. Further, the scanning electron microscopy (SEM) and definitional scanning colorimetric (DSC) techniques were confirmed the phase homogeneity of the cured systems.

• Bulletin of the Korean Chemical Society
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• v.27 no.7
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• pp.1009-1014
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• 2006

Density functional theory calculations are applied to investigate the intramolecular proton transfer in the tautomers of thymine radical cation and its hydrated complexes with one water molecule. The optimized structures and energies for 6 tautomers and 6 transition states of thymine radical cation are calculated at the B3LYP/6-311++G(d,p) level. It is predicted that the order of relative stability for the keto and enol tautomers of thymine radical cation is the same with that of the neutral thymine tautomers, though the enol tautomers are more stabilized with respect to the di-keto form in the radical cation than in the neutral state. A new channel of proton transfer from >C5-$CH_{3}$ of thymine is found to open and have the lowest energy barrier of other proton transfer processes in thymine radical cation. The roles of hydration are also investigated with thymine-water 1 : 1 complex ions. The presence of water significantly lowers the barrier of the proton transfer, which clearly shows the assisting role of hydration even with one water molecule

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.10a
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• pp.90-95
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• 1991

The Uniform Building Code (UBC) is the most widely used requirements for earthquake resistant design in the United States. In this paper, a mid-rise steel building is analyzed by applying 12 sets of actual strong-motion earthquake data that have been scaled to acne 2B levels. The simply extrapolated ground motion displacements are used for the dynamic loads. The results of dynamic analyses for a 10-story steel building are compared with the static and dynamic analysis requirements of UBC-88. It was found that computed lateral fortes using UBC-88 static procedure differed by about 60 percent depending on whether the natural period was computed using the UBC empirical method or the UBC recommended Rayleigh's method. The lateral fortes computed from the UBC response spectra were more than 10 times greater than those computed by UBC static procedures. The lateral forces obtained from both linear and nonlinear analyses using 1989 Loma Prieta ground mot ions compared very well with UBC response spectra results.

• KSBB Journal
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• v.15 no.3
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• pp.318-322
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• 2000

An oxygen-sensitive fumarate reductase has been purified from the cytosol fraction of the Enterococcus faecalis RKY1 grown anaerobically on a defined medium containing glycerol and fumarate. A major portion of the purification was performed with employing Triton X-100 and reducing agents by Phenyl-sepharose CL-4B DEAE-sepharose and Dephadex G-150 The final activity was 0.42 unit/mg. The deduced molecular mass of active band was 66 kDa. The optimal pH and temperature for the activity were 7.0 and 38$^{\circ}C$ respectively. The enzyme activity was not affected by 1mM metal ions such as bacl2 $.$2H2O HgCl2 MnCl2$.$4H2O ZnCl2 CuCl2$.$2H2O Mgcl2$.$6H2O FeSo4$.$7H2O and by EDTA. Partially purified enzyme ws yellow in color ; spectroscopic study indicated the presence of flavins as a cofactor.

• Journal of Life Science
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• v.9 no.4
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• pp.414-422
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• 1999

Our works performed for preparation of oligosaccharides from carrageenan, seaweed polysaccharide, and one active strain for carrageenan was isolated from sea water and identified to Pseudomonas alcaligenes. Carrageenan degrading enzyme was purified from the culture fluid of isolated strain-Pseudomonas alcaligenes JCL-43, by DEAE-Cellulose, Sephadex G-100, Q-Sepharose and CM Sepharose CL-6B column chromatography. Two enzyme-F-I, F-II- was identified this purifying process, and the molecular weight of the purified carrageenase were estimated to be 23.6kDa and 30.2kDa, respectively. The optimum pH and temperature for two carrageenase activity were 7.0 and 4$0^{\circ}C$. These enzymes were stable in the pH range of 6.0~7.5 and lower than 5$0^{\circ}C$, and required 1.5% NaCl for optimum activity. And these carragennase were inhibited by metal ions such as Cu2+, Zn2+, Hg2+, but increased by Ba2+ and Ca2+, and showed specificity on -carrageenan.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.19-19
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• 2003

The injection of spins into nonmagnetic semiconductors has recently attracted great interest due to the potential to create new classes of spin-dependent electronic devices. A recent strategy to achieve control over the spin degree of freedom is based on dilute ferromagnetic semiconductors. Ferromagnetism has been reported in various semiconductor groups including II-Ⅵ, III-V, IV and II-IV,-V$_2$, which will be reviewed. On the other hand, to date the low solubility of magnetic ions in non-magnetic semiconductor hosts and/or low Curie temperature have limited the opportunities. Therefore the search for other promising ferromagnetic semiconducting materials, with high magnetic moments and high Curie temperatures (Tc), is of the utmost importance. In this talk, we also introduce new pure ferromagnetic semiconductors, MnGeP$_2$ and MnGeAs$_2$, exhibiting ferromagnetism and a magnetic moment per Mn at 5K larger than 2.40 ${\mu}$B. The calculated electronic structures using the FLAPW method show an indirect energy gap of 0.24 and 0.06 eV, respectively. We have observed spin injection in MnGeP$_2$ and MnGeAs$_2$ magnetic tunnel junctions through semiconducting barriers.

• Journal of the Korean Chemical Society
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• v.16 no.1
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• pp.6-12
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• 1972

The crystal structure of monoethanolamine hydrochloride is triclinic P1 with two formula units in a cell of dimensions a = $4.42\pm0.02$, b = $7.44\pm0.02$, c = $7.48\pm0.02$, $\alpha$ = $102.4\pm0.3$, $\beta$ = $91.1\pm0.3$, $\gamma$ = $77.2\pm0.3^{\circ}.$ The configuration of monoethanolamine is a gauche form with dihedral angle, $90^{\circ}$. The nitrogen atom forms four hydrogen bonds, three to Cl- ions(3.15, 3.24, $3.28\AA)$ and one to a hydroxyl group of another molecule (N${\cdot}{\cdot}{\cdot}$O, $2.90{\AA})$. The oxygen also forms two such bonds, one to a Cl- ion $(3.14\AA)$, one to an amine group of another molecule (O${\cdot}{\cdot}{\cdot}$N, $2.90{\AA}).$ Molecules are linked into two-dimensional network by hydrogen bonds.

• Korean Journal of Crystallography
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• v.14 no.2
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• pp.67-72
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• 2003

Graphite powders were coated with ZrO₂ by the controlled hydrolysis of a DI water, ethanol and DI water+ethanol solutions. The hydrolysis process was carried out with temperature control because of the low wettability of Zr ions to the surface of the graphite. PVA was added to the solution for the enhancement of metal ion adsorption. The surface of the graphite powders coated with ZrO₂ was observed by SEM and TEM. There are two types of ZrO₂ particles with the condition of ZrOCl₂°§8H₂O aqueous solutions were used; (a) primary particles a few nm in size and (b) secondary particles with ∼0.1 ㎛ size were obtained. The graphite powders coated in 50% ethanol-50% DI water solution of Zr(SO₄)₂ㆍ4H₂O have the relatively uniform coating layer and the starting temperature of oxidation was 100℃ higher than the raw graphite.

• YAKHAK HOEJI
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• v.38 no.4
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• pp.418-424
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• 1994

Lectin from mistletoe (Viscum coloratum) were obtained by salt fractionation, gel filtration and anion exchange chromatography. A molecular weight of about 60,000D has been determined by SDS-PAGE and two basic subunits which have molecular weights of 33,000D and 28,000D are linked by a disulfide bond. The partially purified mistletoe lectins agglutinated human B erythrocytes. Agglutinating activity was relatively stable at varied pH $(3.77{\sim}8.71)$ and at temperature range of $0{\sim}40^{\circ}C$ and not affected by 9 metal ions. Galactose, lactose and N-acetyl-D- galactosamine inhibited agglutinating activity of lectin. Lectin from mistletoe was more mitogenic to murine lymphocytes than concanavalin A.

• Journal of Photoscience
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• v.11 no.32
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• pp.65-69
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• 2004

The mechanism of interaction of four coumarin derivatives (CDS) with bovine serum albumin (BSA) was studied using spectrofluorometric technique. It was found that the coumarin ring common to all CDS makes major contribution to interaction. Binding affinities could be related to parachor values of CDS. Stem-Volmer plots indicated the presence of static component in the quenching mechanism. Results also showed that both tryptophan residues of protein are accessible to CDS. The high magnitude of rate constant of quenching indicated that the process of energy transfer occurs by intermolecular interaction forces and thus CDS binding site is in close proximity to tryptophan residues of BSA. Binding studies in the presence of the hydrophobic probe, 8-anilino-l-naphthalein-sulfonic acid showed that there is hydrophobic interaction between CDS and the probe and they do not share common sites in BSA. Thermodynamic parameters obtained from data at different temperatures showed that the binding of CDS to BSA involve hydrophobic bonds predominantly. The effects of various metal ions on the binding of CDS with BSA were also investigated.