• Animal cells and systems
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• v.1 no.4
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• pp.529-534
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• 1997

Genetic and morphological variations of Rhinogobius giurinus were surveyed. Populations of R.giurinus were clearly divided into two forms (Form-A and Form-B). Starch gel variation of this species. Three loci (Aco, Mpi, aGpd) out of 27 showed fixed allelic differences between Form-A and Form-B and they are well differentiated from each other genetically (Rogers' S=0.871). These two forms, moreover, are found to be allopatric in distribution and morphologi cally different in body length and caudal fin color pattern. Therefore, they are considered as two distinct taxa of subspecific rank. In addition, the genetic relationships among 5 taxa within 4 species of the genus Rhinogobius were investigated. Three species of the Rhinogobius brunneus complex (R.sp. OR, R. sp. CB and R. sp. CO) are well differentiated from each other genetically and two taxa of R. giurinus are genetically divergent from three species of the Rhinosotius brunneus complex (average Nei's D=0.603, average Rogers'=0.534).

• Journal of the Korean Chemical Society
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• v.59 no.3
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• pp.215-224
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• 2015

Unsymmetrical tetradentate Schiff base N-(2-hydroxy-5-methylacetophenone)-N'-(2-hydroxy acetophenone) ethylene diamine (H₂L) and its complexes with Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) have been synthesized and characterized by elemental analyses, magnetic susceptibility measurements, IR, electronic spectra and thermogravimetric analyses. ¹H, ¹³C-NMR and FAB Mass spectra of ligand clearly indicate the presence of OH and azomethine groups. Elemental analyses of the complexes indicate that the metal to ligand ratio is 1:1 in all complexes. Infrared spectra of complexes indicate a dibasic quadridentate nature of the ligand and its coordination to metal ions through phenolic oxygen and azomethine nitrogen atoms. The thermal behavior of these complexes showed the loss of lattice water in the first step followed by decomposition of the ligand in subsequent steps. The thermal data have also been analyzed for the kinetic parameters by using Horowitz-Metzger method. The dependence of the electrical conductivity on the temperature has been studied over the temperature range 313-403 K and the complexes are found to show semiconducting behavior. XRD and SEM images of some representative complexes have been recorded. The antimicrobial activity of the ligand and its complexes has been screened against various microorganisms and all of them were found to be active against the test organisms. The Fe(III) and Ni(II) complex have been tested for the catalytic oxidation of styrene.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.205-211
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• 1992

The $2{\nu}_{C=0}$ + amide III combination band spectrum of acetamide (AA) was obtained in very dilute solutions of AA+lanthanide shift reagents (LSR) in carbon tetrachloride over the range of $15^{\circ}$ to $45^{\circ}C$. It was found that only 1 : 1 AA-LSR complex is formed by the interaction between carbonyl oxygen of AA and central metal ion(Ln(Ⅲ)) in LSR. The thermodynamic parameters for Ln(III)${\cdot}$O=C bond were determined by computer analysis of concentration and temperature dependent spectra. ${\Delta}H^{\circ}$ for the coordination of AA to Eu$(dpm)_3$, Yb$(dpm)_3$, and Pr$(dpm)_3$ have been found to be -39.1, -28.4, and -25.5 kJ/mol, respectively. It has shown that this type of ion-dipole interaction is more than twice stronger compared to the dipole-dipole interaction in the amide linkage, and largely depending on the steric hindrence effect by the bulky dpm groups around central metal ion (Ln(III)) rather than the ionic potential effect of central metal ion itself.

• Journal of the Korean Chemical Society
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• v.57 no.6
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• pp.703-711
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• 2013

In the present investigation, kinetic studies of oxidation of formic acid with and without catalyst and promoter in aqueous acid media were studied under the pseudo-first order conditions [formic acid]T ${\gg}[Cr(VI)]_T$ at room temperature. In the 1,10-phenanthroline (phen) promoted path, the cationic Cr(VI) phen complex is the main active oxidant species undergoes a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition through several steps leading to the products $CO_2$ and $H_2$ along with the Cr(III) phen complex. The anionic surfactant (i.e., sodium dodecyl sulfate, SDS) and neutral surfactant (i.e., Triton X-100, TX-100) act as catalyst and the reaction undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Whereas the cationic surfactant (i.e., N-cetyl pyridinium chloride, CPC) acts as an inhibitor restricts the reaction to aqueous phase. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. The neutral surfactant TX-100 has been observed as the suitable micellar catalyst for the phen promoted chromic acid oxidation of formic acid.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.515-522
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• 2010

A relation between antimicrobial activities and the formation constants of solid complexes of Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) with tridentate Schiff base ligand, 4-hydroxy-3(1-{2-(benzylideneamino)-phenylimino}-ethyl)-6-methyl-2Hpyran-2-one (HL) derived from o-phenylene diamines, dehydroacetic acid (DHA) and p-chloro benzaldehyde have been studied. The ligand and metal complexes were characterized by elemental analysis, conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, $^1H$-NMR, UV-vis and mass spectra. From the analytical data, the stiochiometry of the complexes was found to be 1:2 (metal:ligand) with octahedral geometry. The molar conductance values suggest the nonelectrolytic nature of metal complexes. The X-ray diffraction data suggests monoclinic crystal system for Ni(II) and orthorhombic crystal system for Cu(II) and Co(II) complexes. The IR spectral data suggest that the ligand behaves as tridentate ligand with ONN donor atoms sequence towards central metal ion. Thermal behavior (TG/DTA) and kinetic parameters calculated by Coats-Redfern method suggests more ordered activated state in complex formation. The protonation constants of the complexes were determined potentiometrically in THF:water (60:40) medium at $25^{\circ}C$ and ionic strength ${\mu}=0.1\;M$ ($NaClO_4$). Antibacterial activities in vitro were performed against Staphylococcus aureu and Escherichia coli. Antifungal activities were studied against Aspergillus Niger and Trichoderma. The effect of the metal ions and stabilities of complexes on antimicrobial activities are discussed.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.135-145
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• 2000

It is well known that there are different craniofacial skeletal groups in the same malocclusion types. The present study was performed to determine morphologic sub-groups in Korean children with Class III malocclusions, and to find out morphological differences between subgroups by means of a cross-sectional longitudinal cephalometric study. In this study, 135 children aged 6 to 14 year-old with untreated Class III malocclusions were selected. The samples were divided into two groups depending on the angulation of middle cranial fossa (MCF). That is, when the MCF of an individual was measured smaller than 40.3, he/she was tossed into mandibular protrusive-effect group(MREG), while when an individual was measured larger than 40.3, he/she was tossed into mandibular retrusive-effect group(MREG). Thereafter, the grouped samples were divided into 4 age groups(7, 9, 11 and 13 year-old). Thirty four linear and angular measurements on the tracings of lateral cephaloradiographs were measured, and the morphological characteristics and differences were compared and analysed by means of Wilcoxon test. It was found that Korean children with Class III malocclusions were divided into two groups, in which 39.3% were belonged in the MREG and 60.7% were in the MREG. In the MREG, anterior-posterior length of cranial base, nasomaxillary complex, maxilla and mandible were larger than the MREG. And although there was no difference in the total length of mandible (Co-Gn), mandibular body length (Go-Gn) was larger in the MREG during the majority of the observed periods. These results would suggest that a majority of the samples, 60.7%, demonstrated many of configurations of craniofacial skeletal relationships that can be found in the leptoprosopic faceform.

• BMB Reports
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• v.44 no.4
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• pp.244-249
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• 2011

The quality of a phage-displayed antibody library deteriorates with clonal variations, which are caused by differentially expressed Escherichia coli antibody genes. Using the human Fab SP114 against the pyruvate dehydrogenase complex-E2 (PDCE2), we created four E. coli TOP10F' clones with a pCMTG phagemid encoding Fab-pIII (pCMTG-Fab), Fd ($V_H+C_{H1}$)-pIII (pCMTG-Fd), or light chain (L) (pCMTG-L), or the vector only (pCMTG-${\Delta}Fab$) to investigate the effect of clonal variations in a defined manner. Compared to the others, the E. coli clone with pCMTG-Fab was growth retarded in liquid culture, but efficiently produced phage progenies by Ex12 helper phage superinfection. Our results suggest that an antibody library must be cultured for a short duration before helper phage superinfection, and that the Ex12 helper phage helped to alleviate the detrimental effect of clonal variation, at least in part, by preferentially increasing functional phage antibodies during phage amplification.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.769-776
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• 2008

The stereoselective synthesis of chiral terminal epoxide is of immense interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new chiral Co(salen) complexes bearing cobalt(II) chloride, iron(III) chloride and zinc(II) nitrate have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of terminal epoxides such as styrene oxide and phenylglycidylether by hydrolytic kinetic resolution technology and for the synthesis of glycidyl buthylate. The easily prepared complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (>99% ee). The newly synthesized chiral salen showed remakablely enhanced reactivity with substantially low loadings. The system described in this work is very efficient for the sinthesis of chiral epoxide and 1,2-diol intermediates.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.726-734
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• 2008

While the structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers has to be carried out in consideration of sloshing impact pressure, it is very difficult to figure out its dynamic response behaviors due to its very complex structural arrangements/materials and complicated phenomena of sloshing impact loading. For the development of its original technique, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In this study, for the exact understanding of dynamic response behavior of CCS structure in membrane Mark III type LNG carriers under sloshing impact pressure, its wet drop impact response analyses were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. It might be thought that the structural response behaviors of impact response analysis, such as impact pressure impulses and resulted strain time histories, generally showed very good agreement with experimental ones with very appropriate use of FSI analysis technique of LS-DYNA code, finite element modeling and material properties of CCS structure, finite element modeling and equation of state(EOS) of fluid domain.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.3
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• pp.161-173
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• 2023

This study investigated the effects of K_N and process time on the formation of a compound layer at a nitriding temperature of 540℃ for SCR420H material. As a result of controlled nitriding from 3 h to 20 h at K_N 1.2 atm^-1/2, compound layers were formed up to about 10 ㎛, and an effective hardening depth of about 460 ㎛ was obtained. Initially, an ε+γ' complex phase was formed, and the phase fraction changed over time, and finally, the fraction of ε phase decreased to less than 1%. With higher K_N, the compound thickness increased, a pore layer was formed on the surface, and the surface hardness decreased. By applying the controlled nitriding process, it was possible to produce annulus gears with a compound thickness of 12.8 ㎛ and an ε phase of 5% or less. The annulus gears made through controlled nitriding were mounted on a 6-speed transmission and tested for durability. As a result, the durability test of 250,000 km was satisfied, and the transmission efficiency was also confirmed to be expected.