• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.106-108
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• 2005

The rutile polycrystal $Ti_{0.99}\;^{57}Fe_{0.01}O_2$ prepared with $^{57}Fe$ enriched iron have been studied by $M\ddot{o}ssbauer$ spectroscopy, X-ray diffraction and VSM. The $M\ddot{o}ssbauer$ spectrum of $Ti_{0.99}\;^{57}Fe_{0.01}O_2$ consists of a ferromagnetic and a paramagnetic phase over all temperature ranging from 4 to 300 K. Isomer shifts indicate $Fe^{2+}$ for the ferromagnetic phase, but $Fe^{3+}$ for the paramagneic phase of $Ti_{0.99}\;^{57}Fe_{0.01}O_2$ sample. It is noted that the magnetic hyperfine field of ferromagnetic phase had the value about 1.48 times as large as that of $\alpha$-Fe. The XRD data for $Ti_{0.99}\;^{57}Fe_{0.01}O_2$ showed a pure rutile phase with tetragonal structures without any segregation of Fe into particulates within the instrumental resolution limit The magnetic hysteresis (M-H) curve at room temperature showed an obvious ferromagnetic behavior and the magnetic moment per Fe atom under the applied field of 1 T was estimated to be about $0.71{\mu}_B$, suggesting a low spin configuration of Fe ions.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.1980-1984
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• 2007

An HPLC chiral stationary phase (CSP) which has only two ureide functional groups was prepared starting from (1S,2S)-1,2-diaminocyclohexane. The CSP was successful in the resolution of various N-(3,5- dinitrobenzoyl)-α-amino acids, the separation (α) and the resolution factors (RS) being within the range of 1.11-1.35 and 2.19-5.17, respectively with the use of 20% 2-propanol in hexane containing 0.1% trifluoroacetic acid as a mobile phase. However, ethyl esters of N-(3,5-dinitrobenzoyl)-α-amino acids were not resolved or resolved with only marginal separation and resolution factors on the CSP under the identical mobile phase condition. From these results, the complexation of the carboxylate anions of analytes inside the double-ureide pocket of the CSP was expected to play some important role for the chiral recognition. In contrast, N-(3,5- dinitrobenzoyl)-α-amino acid N-propylamides were resolved on the CSP with reasonable separation and resolution factors. Enantioselective hydrogen bonding interactions between analytes and the CSP were presumed to be responsible for these resolutions.

• Korean Journal of Crystallography
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• v.8 no.1
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• pp.33-37
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• 1997

The optical properties of (1210) GaN epitaxy films grown on the (1012) $\alpha-A1_2O_3$ substrates have been studied. The hetero-epitaxy films were grown by the halide vapor phase epitaxy (HVPE) method using $Ga/HC1/NH_3/He$ system at $990^{\circ}C$. XRD, RHEED and SEM are used for the identification of the hetero-epitaxy films structure and surface morphology. The confirmed (1210) GaN epitaxy films were characterized by PL and Raman. By the Raman scattering, the active phonon modes of single-phase GaN films are varied with the arrangement of both polarization and propagation directions of laser beam with reference to the axis in single-phase crystal films. The Y(Z, Y & Z) X geometry allows scattering pat-terns of $A_1(TO)=533\;cm^{-1},\;E_1(TO)=559\;cm^{-1}\;and\;E_2=568 cm^{-1}$ modes, whereas in the Z(Y, Y & Z) X geometry the only $E_2$ mode are observed.

• KSBB Journal
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• v.18 no.4
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• pp.306-311
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• 2003

Solid-phase refolding of immobilized proteins can be an effective way to reuse an immobilized enzyme column. Oriented immobilization methods are known to provide higher activity of the immobilized enzymes. In this study, using recombinant EK (enterokinase) as a model enzyme and a fusion protein, that consisted of recombinant human growth hormone and six His tag that was linked by the peptide of EK-specific recognition sequence, as a model substrate, we evaluated two oriented immobilization methods, i. e., reductive alkylation of N-terminus ${\alpha}$-amine and affinity interaction between poly-histidine tag and Ni-NTA (nickel-nitrilotriacetic acid). The immobilization yield, activity and cleavage of the immobilized enzymes, and the yield of solid-phase refolding were compared. The Ni affinity immobilization and the covalent immobilization yields were about 100％ and 65％, respectively. But the specific activities were the same, about 50％ of that of the soluble enzyme. The cleavage rate by the covalently immobilized EK was higher than the soluble enzyme and the side reaction of cryptic cleavage was significantly decreased. Covalently immobilized EK showed almost 100％ refolding yield but the affinity immobilized EK showed only 70％ yield, which suggested the covalent conjugation provided more rigid ‘reference structure’ for the solid-phase refolding. The monomeric hGH could be easily obtained by capturing the cleaved poly Histidine tag by the Ni affinity column.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.9-23
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• 1994

Epitaxial $CoSi_2$ layer has been grown on NaCl(100) substrate at low deposition temperature($200^{\circ}C$) by multitarget bias cosputter deposition(MBCD). The phase sequence and crystallinity of deposited silicide as a function of deposition temperature and substrate bias voltage were studied by X-ray diffraction(XRD) and transmission electron microscopy(TEM) analysis. Crystalline Si was grown at $200^{\circ}C$ by metal induced crystallization(M1C) and self bias effect. In addition to, the MIC was analyzed both theoretically and experimentally. The observed phase sequence was $Co_2Si \to CoSi \to Cosi_2$ and was in good agreement with that predicted by effective heat of formation rule. The phase sequence, the CoSi(l11) preferred orientation, and the crystallinity had stronger dependence on the substrate bias voltage than the deposition temperature due to the collisional cascade mixing, the in-situ cleaning, and the increase in the number of nucleation sites by ion bombardment of growing surface. Grain growth induced by ion bombardment was observed with increasing substrate bias voltage at $200^{\circ}C$ and was interpreted with ion bombardment dissociation model. The parameters of $E_{Ar}\;and \alpha(V_s)$ were chosen to properly quantify the ion bombardment effect on the variation in crystallinty at $200^{\circ}C$ with increasing substrate bias voltage using Langmuir probe.

• Investigative Magnetic Resonance Imaging
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• v.17 no.4
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• pp.259-266
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• 2013

Purpose : To investigate the blood pharmacokinetics and bio-distribution of DTPA-bis-amide (L3) Gd(III) complexes. Materials and Methods: The pharmacokinetics and bio-distribution of Gd $(L3)(H_2O){\cdot}nH_2O$ were investigated in Sprague-Dawley rats after intravenous administration at a dose of 0.1 mmol Gd/kg. The Gd content in the blood, various tissues, and organs was determined by ICP-AES. Blood pharmacokinetic parameters were calculated using a two-compartment model. Results: The half-lives of ${\alpha}$ phase and ${\beta}$ phase Gd $(L3)(H_2O){\cdot}nH_2O$ were $2.286{\pm}0.11$ min and $146.1{\pm}7.5$ min, respectively. The bio-distribution properties reveal that the complex is mainly excreted by the renal pathway, and possibly excreted by the hepatobiliary route. The concentration ratio of Gd (III) was significantly higher in the liver and spleen than in other organs, and small amounts of Gd (III) ion were detected in the blood or other tissues of rats only after 7 days of intravenous administration. Conclusion: The MRI contrast agent Gd $(L3)(H_2O){\cdot}nH_2O$ provides prolonged blood pool retention in the circulation and then clears rapidly with minimal accumulation of Gd(III) ions. The synthesis of gadolinium complexes with well-balanced lipophilicity and hydrophilicity shows promise for their further development as blood pool MRI contrast agents.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.2
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• pp.65-69
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• 2014

Crystallographic phases of Plasma electrolytic oxidized Al alloy, A1100, A5052, A6061, A6063, A7075, were investigated. Two types of electrolyte $Na_2Si_2O_3$ and Na2P2O7 were also compared. Bipolar pulse, $2000{\mu}sec$ with $400{\mu}sec+420V$ impulse and $300{\mu}sec$ - impulse were applied for 20 min. ${\alpha}-alumina$, ${\gamma}-alumina$, ${\eta}-alumina$, $Al_{4.95}Si_{1.05}O_{9.52}$, and $(Al_{0.9}Cr_{0.1})_2O_3$ were mainly observed. Si, component of electrolyte, were moved into the PEO layer by bipolar pulse. Glassy phase was also observed at the surface of $Na_2Si_2O_3$ electrolyte treated PEO layer, and increased with the Mg content of Al alloy. It is concluded that at first glassy phase was formed by the micro plasma, and the high temperature of plasma turns glassy phase to several crystalline phases. And we could expect that many other crystalline phase could be formed by PEO process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.3
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• pp.99-105
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• 2018

In order to avoid un-uniform crystallization on the surface of a quartz glass crucible that is known to affect the production yield of the single crystal silicon, Ba (barium) was selected as a crystallization promotor and the inner surface of the crucible was coated using Ba (barium hydroxide octahydrate)-solution by the spray pyrolysis method. For un-coated crucible, it was found that the crystallization of its surface started at $1350^{\circ}C$, and at $1450^{\circ}C$ the surface was uniformly crystallized with ${\beta}$-cristobalite phase. It was found that the crucible coated with Ba began to be crystallized from $1000^{\circ}C$ and was uniformly crystallized on the crucible surface at $1300^{\circ}C$. In this case, ${\alpha}$-cristobalite and needle-shaped $BaSi_2O_5$ phase were created and disappeared as a crystal phase, and the ${\beta}$-cristobalite phase was eventually evenly distributed over the Ba-coated crucible surface.

• Korean Journal of Food Science and Technology
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• v.46 no.4
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• pp.425-431
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• 2014

In this study, the volatile compounds in 24 commercial Korean black raspberry wines were isolated by headspace solid-phase microextraction and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 43 volatile components, including 15 esters, 12 terpenes, 7 alcohols, 4 acids, 3 ketones, and 2 aldehydes, were identified. Ethyl esters and alcohols such as ethyl acetate, ethyl octanoate, isoamyl alcohol, and phenethyl alcohol were the most represented groups among the quantified volatiles. In particular, various terpenes such as DL-limonene, linalool, alpha-terpineol, and myrtenol were identified. The differences in volatile components among the 24 black raspberry wines and possible sample grouping were examined by applying principal component analyses to the GC-MS data sets. The first and second principal components explained 43.9% of the total variation across the samples. No apparent sample groupings were observed according to manufacturing locations. The samples KU, BH, SR, and MO showed higher overall levels in the concentrations of terpenes originating from black raspberry, while other samples such as BB and HB, showed higher in ethyl ester and alcohol contents produced by yeast fermentation, respectively.

• Journal of Microbiology and Biotechnology
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• v.7 no.5
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• pp.323-328
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• 1997

The recombinant Escherichia coli BL21(DE3)pLysE : pTCGT1 was grown to overproduce Bacillus macerans cyclodextrin glucanotransferase (CGTase) able to synthesize ${\alpha}$-cyclodextrin (CD) with a selectivity of 67%. A number of batch fermentations were performed to test the possibility of using lactose as an inducer of the E. coli T7 promoter system. A mixture of isopropyl ${\beta}$-D-thiogalactoside (IPTG) and lactose (1 : 1) gave a maximum CGTase activity of 2.4 U/ml, which was higher than the value obtained with induction by IPTG alone. Fed-batch fermentations involving a glucose-controlled growth period followed by a gene-expression phase with mixtures of IPTG and lactose were employed to achieve high cell density and thereby increase total CGTase activity. Optimized fed-batch fermentation using the modified inducer (IPTG : lactose=1 : 3) and 100 g/l yeast extract solution in the gene-expression phase resulted in a maximum CGTase activity of 62.9 U/ml and a final cell mass of 53.5 g/l, corresponding to a 31-fold increase in CGTase activity and a 29-fold increase in cell mass compared with the control batch fermentation.