• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.9-18
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• 2017

Nine bacilli with fibrinolytic activities were isolated from doenjang, a traditional Korean fermented soy food. Among them, RSB34 showed the strongest activity and was identified as Bacillus amyloliquefaciens by 16S rRNA and recA gene sequencing. During growth on LB up to 96 h, RSB34 showed the highest fibrinolytic activity ($83.23mU/{\mu}l$) at 48 h. Three bands of 23, 27, and 42 kDa in size were observed when the culture supernatant was analyzed by SDS-PAGE and 27 and 42 kDa bands by fibrin zymography. The gene encoding the 27 kDa fibrinolytic enzyme AprE34 was cloned by PCR. BLAST analyses confirmed that the gene was a homolog to genes encoding AprE-type proteases. aprE34 was overexpressed in Escherichia coli BL21(DE3) using pET26b(+). Recombinant AprE34 was purified and examined for its properties. The $K_m$ and $V_{max}$ values of recombinant AprE34 were $0.131{\pm}0.026mM$ and $16.551{\pm}0.316{\mu}M/l/min$, respectively, when measured using an artificial substrate, N-succinyl-ala-ala-pro-phe-p-nitroanilide. aprE34 was overexpressed in B. subtilis WB600 using pHY300PLK. B. subtilis transformants harboring pHYRSB34 (pHY300PLK with aprE34) showed higher fibrinolytic activity than B. amyloliquefaciens RSB34.

• Journal of Pharmaceutical Investigation
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• v.30 no.2
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• pp.113-118
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• 2000

In order to assay the efficacy of newly synthesized antiviral compounds, pyrimidine analogs, pharmacokinetics of those were established as compared with already marketed zidovudine. Zidovudine (15, 20, 25 and 35 mg/kg), LJ142 (18.52 mg/kg) and LJ143 (15, 18.52 and 30 mg/kg) were administered orally and intravenously in rats, blood samples were collected post-injection(i.e., for 360 min) at appropriate time intervals. Those were analyzed by HPLC with UV detection at 265 nm. Pharmacokinetic parameters $(C_{max},\;T_{1/2},\;MRT,\;AUC,\;AUMC,\;Vd_{SS},\;Cl_t)$ were calculated. AUCs of zidovudine and LJ143 following I.V. dosing of $15{\sim}25\;mg/kg\;and\;15{\sim}18.18\;mg/kg$ were dose-independent. However, AUCs of zidovudine and LJ43 following I.V. dosing of $25{\sim}35\;mg/kg\;and\;18.18{\sim}30\;mg/kg$ were dose-dependent. The relative bioavailability of zidovudine, LJ142 and LJ143 following oral administration were 61.94, 46.44 and 78.24%, respectively.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.145-149
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• 2016

$(Bi_{1/2}Na_{1/2})_{0.94}Ba_{0.06}(Ti_{1-x}Nb_x)O_3$ (BNBTxNb) ceramics were investigated in terms of the crystal structure as well as the ferroelectric, dielectric, and piezoelectric properties. While little change was observed in the microstructure except for a slight decrease in the average grain size, a significant change was noticed in the temperature dependence of dielectric and piezoelectric properties. It was shown that the property changes are closely related to the downward shift in the position of the ferroelectric-to-relaxor transition temperature with increasing amount of Nb doping. A special emphasis is put on the fact that Nb doping is so effective at decreasing the ferroelectric-to-relaxor transition temperature that even at no more than 2 at.% Nb addition, the transition temperature was already brought down slightly below room temperature, resulting in the birth of a large strain at 0.46 %, equivalent to $S_{max}/E_{max}=767pm/V$.

• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.93-98
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• 2013

In this paper, four conducting polymers (poly[(N-butyl-phenothiazine)-sulfide] (PBPS), poly[(N-hexyl-phenothiazine)-sulfide] (PHPS), poly[(N-decyl-phenothiazine)-sulfide] (PDPS), and poly[(N-(2-ethylhexyl)-phenothiazine)-sulfide] (PEHPS)) were synthesized with a high temperature and high pressure reaction. The structures of synthesized polymers were confirmed by $^1H-NMR$ and characterized by UV-Vis, cyclic voltammetry, and GPC. From the UV-Vis absorption spectra, the ${\lambda}_{max}$ values of PBPS, PHPS, PDPS, and PEHPS were 338, 341, 340, and 334 nm, respectively and their optical band gaps were 3.11, 3.13, 3.16, and 3.05 eV, respectively. To evaluate the feasible applicability as a photovoltaic cell, the devices composed of for example, ITO/PEDOT : PSS/polymer (PBPS, PDPS) : $PC_{71}BM$ (1 : 3, w/w)/$BaF_2$/Ba/Al were fabricated using the blends of the PBPS and PDPS as a donor, and $PC_{71}BM$ as an acceptor. Then, the power conversion efficiencies (PCE) of devices were estimated as 0.076% of PBPS and 0.136% of PDPS by solar simulator.

• Journal of Microbiology and Biotechnology
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• v.17 no.11
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• pp.1789-1796
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• 2007

A ${\beta}$-glucosidase with the molecular mass of 160,000 Da was purified to homogeneity from cell extract of a cellulolytic bacterium, Cellulomonas uda CS1-1. The kinetic parameters ($K_m$ and $V_{max}$) of the enzyme were determined with pNP-cellooligosccharides (DP 1-5) and cellobiose. The molecular orbital theoretical studies on the cellulolytic reactivity between the pNP-cellooligosaccharides as substrate (S) molecules and the purified ${\beta}$-glucosidase (E) were conducted by applying the frontier molecular orbital (FMO) interaction theory. The results of the FMO interaction between E and S molecules verified that the first stage of the reaction was induced by exocyclic cleavage, which occurred in an electrophilic reaction based on a strong charge-controlled reaction between the highest occupied molecular orbital (HOMO) energy of the S molecule and the lowest occupied molecular orbital (LUMO) energy of the hydronium ion ($H_3O^+$), more than endocyclic cleavage, whereas a nucleophilic substitution reaction was induced by an orbital-controlled reaction between the LUMO energy of the oxonium ion ($SH^+$) protonated to the S molecule and the HOMO energy of the $H_2O_2$ molecule. A hypothetic reaction route was proposed with the experimental results in which the enzymatic acid-catalyst hydrolysis reaction of E and S molecules would be progressed via $SN_1$ and $SN_2$ reactions. In addition, the quantitative structure-activity relationships (QSARs) between these kinetic parameters showed that $K_m$ has a significant correlation with hydrophobicity (logP), and specific activity has with dipole moment, respectively.

• Current Applied Physics
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• v.18 no.12
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• pp.1523-1527
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• 2018

The thermal stability, magnetic and magnetocaloric properties of $Gd_{55}Co_{35}M_{10}$ (M = Si, Zr and Nb) melts-pun ribbons were studied. The relatively high reduced glass transition temperature ($T_{x1}/T_m$ > 0.60) and low melting point ($T_m$) resulted in excellent glass forming ability (GFA). The Curie temperatures ($T_C$) of melt-spun amorphous ribbons $Gd_{55}Co_{35}M_{10}$ for M = Si, Zr and Nb were 166, 148 and 173 K, respectively. For a magnetic field change of 2 T, the values of maximum magnetic entropy change $(-{\Delta}S_M)^{max}$ for $Gd_{55}Co_{35}Si_{10}$, $Gd_{55}Co_{35}Zr_{10}$ and $Gd_{55}Co_{35}Nb_{10}$ were found to be 2.86, 4.28 and $4.05J\;kg^{-1}K^{-1}$, while the refrigeration capacity (RC) values were 154, 274 and $174J\;kg^{-1}$, respectively. The $RC_{FWHM}$ values of amorphous alloys $Gd_{55}Co_{35}M_{10}$ (M = Si, Zr and Nb) are comparable to or larger than that of $LaFe_{11.6}Si_{1.4}$ crystalline alloy. Large values of $(-{\Delta}S_M)^{max}$ and RC along with good thermal stability make $Gd_{55}Co_{35}M_{10}$ (M = Si, Zr and Nb) amorphous alloys be potential materials for magnetic cooling operating in a wide temperature range from 150 to 175 K, e.g., as part of a gas liquefaction process.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.197-210
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• 2005

Results of 7 nights of CCD VR photometry of the intermediate polar 1RXS J062518.2+733433 obtained at the Korean 1.8m telescope are reported. The corrected ephemeris for the orbital minimum is BJD (Orb.min) = 2453023.6159(42)+0.1966431(33) (E-1735). The corrected ephemeris for the spin maximum is BJD (spin max) = 2452893 78477 (10)+0.01374116815 (17) (E-15382) (cycle numbering corresponds to that of Staude et al.2003). The variations of the shape of the individual spin variations are highly correlated in V and R. The phase of the spin maximum is found to be dependent on the orbital phase. The corresponding semi-amplitude of sinusoidal variations of phase is $0.11{\pm}0.03.$ This new phenomenon is explained by the changing viewing conditions of the accreting magnetic white dwarf, and should be checked in further observations this star and for other intermediate polars. To avoid influence of this effect on the analysis of the long-term spin period variations, the runs of at least one orbital period are recommended. Results of time series analysis are presented in tables.

• Journal of Pharmaceutical Investigation
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• v.29 no.1
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• pp.13-19
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• 1999

Canalicular liver plasma membrane vesicles (cLPM) were prepared according to two different methods (Inoue method and Meier method), and were evaluated for their protein yield, enzyme activity and transport characteristics. No difference was found between the methods in the protein yield (i.e., $0.14{\pm}0.031$ and $0.15{\pm}0.050$ mglg liver for Inoue method and Meier method, respectively). The activity of alkaline phosphatase, a marker enzyme of canalicular membrane, was significantly (P<0.05) higher in the vesicles of Meier method $(3.52{\pm}0.91\;mmol/mg/hr)$than in the vesicles of Inoue method ($2.28{\pm}0.94$ mmol/mg/hr) indicating that more purified cLPM were obtained from Meier method compared with Inoue method. ATP-dependent vesicular uptake of taurocholate and tributylmethylammonium (TBuMA) was observed for vesicles of both methods, and the kinetic parameters responsible for the transport were similar between the vesicles of both methods (for example, $V_{max}:$ 9.72 nmol/mg protein/30sec and $K_m:$ 0.63 mM for Inoue method; $V_{max}:$ 10.1 nmol/mg protein/30sec and $K_m:$ 0.70 mM for Meier method). A pH gradient dependent counter transport of TBuMA was also observed for both vesicles with similar kinetic characteristics. Either the uptake of taurocholate in the absence of ATP or that of TBuMA in the absence of pH gradient, which may represent passive diffusion of respective compound into the vesicles, was more rapid for the vesicles of Meier method than for the vesicles of Inoue method. For example, passive diffusion rate constants $(K_d)$ for TBuMA uptake into the vesicles were 0.00030 and 0.00052\;{\mu}l/mg$ protein/min for the vesicles of Inoue method and Meier method, respectively. It may indicate that more leaky vesicles are obtained form the Meier method compared with the Inoue method. These aspects together with the time necessary to prepare the vesicles (i.e., 8 hr for Inoue method and 23 hr for Meier method) should be considered before selecting an appropriate method for the preparation of cLPM.

• Journal of Microbiology and Biotechnology
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• v.27 no.7
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• pp.1216-1222
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• 2017

To develop starters for the production of functional foods or materials, lactic acid bacteria producing ${\gamma}-aminobutyric$ acid (GABA) were screened from jeotgals, Korean fermented seafoods. One isolate producing a high amount of GABA from monosodium $\text\tiny{L}$-glutamate (MSG) was identified as Enterococcus avium by 16S rRNA gene sequencing. E. avium M5 produced $18.47{\pm}1.26mg/ml$ GABA when incubated for 48 h at $37^{\circ}C$ in MRS broth with MSG (3% (w/v)). A gadB gene encoding glutamate decarboxylase (GAD) was cloned and overexpressed in E. coli BL21 (DE3) using the pET26b (+) expression vector. Recombinant GAD was purified through a Ni-NTA column and the size was estimated to be 53 kDa by SDS-PAGE. Maximum GAD activity was observed at pH 4.5 and $55^{\circ}C$and the activity was dependent on pyridoxal 5'-phosphate. The $K_m$ and $V_{max}$ values of GAD were $3.26{\pm}0.21mM$ and $0.0120{\pm}0.0001mM/min$, respectively, when MSG was used as a substrate. Enterococcus avium M5 secretes a lot of GABA when grown on MRS with MSG, and the strain is useful for the production of fermented foods containing a high amount of GABA.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.6
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• pp.1-6
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• 2011

A transparent oxide thin film transistors (Transparent Oxide-TFT) have been fabricated by RF magnetron sputtering at room temperature using amorphous indium zinc oxide (a-IZO) as both of active channel and source/drain, gate electrodes and co-sputtered $HfO_2-Al_2O_3$ (HfAIO) as gate dielectric. In spite of its high dielectric constant > 20), $HfO_2$ has some drawbacks including high leakage current and rough surface morphologies originated from small energy band gap (5.31eV) and microcrystalline structure. In this work, the incorporation of $Al_2O_3$ into $HfO_2$ was obtained by co-sputtering of $HfO_2$ and $Al_2O_3$ without any intentional substrate heating and its structural and electrical properties were investigated by x-ray diffraction (XRD), atomic force microscopy (AFM) and spectroscopic ellipsometer (SE) analyses. The XRD studies confirmed that the microcrystalline structures of $HfO_2$ were transformed to amorphous structures of HfAIO. By AFM analysis, HfAIO films (0.490nm) were considerably smoother than $HfO_2$ films (2.979nm) due to their amorphous structure. The energy band gap ($E_g$) deduced by spectroscopic ellipsometer was increased from 5.17eV ($HfO_2$) to 5.42eV (HfAIO). The electrical performances of TFTs which are made of well-controlled active/electrode IZO materials and co-sputtered HfAIO dielectric material, exhibited a field effect mobility of more than $10cm^2/V{\cdot}s$, a threshold voltage of ~2 V, an $I_{on/off}$ ratio of > $10^5$, and a max on-current of > 2 mA.