• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.123-124
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• 2007

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.80.1-80
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• 2000

• Journal of Microbiology and Biotechnology
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• v.8 no.5
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• pp.501-508
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• 1998

An alkalophilic mi.croorganism (strain YB380), which produces yeast cell wall hydrolase extracellulary, was isolated from Korean soil. The rod-shaped cells were 0.3~0.4 by 2~4${\mu}{\textrm}{m}$ long, motile, aerobic, gram-positive, and spore-forming. The color of the colony was light yellow. The temperature range for growth at pH 9.0 was 25 to $45{\circ}C, with optimum growth at $35{\circ}C. The pH range for growth at $35{\circ}C was 8 to 11 with an optimum pH of 9.0. Therefore, the strain YB380 is an obligate alkalophile. The 16S rRNA of strain YB380 has a 99% sequence similarity with that of Bacillus alcalophilus. On the basis of physiological properties, cell wall fatty acid composition, and phylogenetic analysis, we propose that the isolated strain is Bacillus alcalophilus. The yeast cell wall hydrolase from Bacillus alcalophilus subsp. YB380 has been purified and partially characterized. The molecular weight was estimated to be 27,000 daltons with an optimum temperature and pH of $60{\circ}C and 9.0, respectively. The N-terminal amino acid sequence of the enzyme was analyzed as Gln- Thr- Val- Pro- Trp- Gly- Ile- Asn- Arg- Val.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.347-355
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• 2012

In this study, non-point pollution sources in the Yeongsan river basin are analyzed; then, the priority regions (areas divided on a small scale) of management are selected for efficient water management of the Seungcheon and Jooksan reservoirs, which were constructed as one of the 4 major rivers restoration projects. The priority regions are decided by using the criteria of the excessive rate of target water quality, non-point pollution load per unit area, total TP load and down flow distance. The results of this study are as follows. The upper 10% of the priority regions for non-point pollution management includes YB15, YB05, YB10, YB24, YB14 and YB11 for the Seungcheon reservoir watershed, and YC24, YC25, YC30, YC34, YC22 and YC17 for the Jooksan reservoir watershed. However, a few regions in each of the Seungcheon and Jooksan reservoirs need to be selected in higher order, and the non-point pollution removal facilities in the regions need to be installed with respect to budget, urgent matter, and so on.

• Korean Journal of Materials Research
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• v.28 no.6
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• pp.355-360
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• 2018

$LuNbO_4:0.2Yb^{3+},xTm^{3+}$ powders were prepared using a solid-state reaction process. The effects of the amount of Tm on up-conversion(UC) and down-conversion(DC) luminescence properties are investigated. X-ray diffraction patterns confirm that $Yb^{3+}$ and $Tm^{3+}$ ions are successfully incorporated into Lu sites. Under 980 nm excitation, the UC spectra of the powders predominantly exhibit strong near-infrared emission bands that peak at 805 nm, whereas weak 480 nm emission bands are observed as well. The emission bands are assigned to the $^1G_4{\rightarrow}^3H_6$ (480 nm) and 3 $^3H_4{\rightarrow}^3H_6$ (805 nm) transitions of the $Tm^{3+}$ ions via an energy transfer from $Yb^{3+}$ to $Tm^{3+}$; two- and three-photon UC processes are responsible for the 805 and 480 nm emissions, respectively. The DC emission spectra exhibit blue emission ($^1D_2{\rightarrow}^3F_4$) of $Tm^{3+}$ at 458 nm. The amount of Tm affects the emission intensity with the strongest emissions at x = 0.007 and 0.02 for the UC and DC luminescence, respectively. The results demonstrate that $LuNbO_4:Yb^{3+},Tm^{3+}$ phosphors are suitable for bio-applications.

• Microbiology and Biotechnology Letters
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• v.44 no.3
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• pp.324-332
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• 2016

A bacterial strain capable of hydrolyzing xylan was isolated from fermented soybean paste obtained from a domestic Buddhist temple, using enrichment culture with rice straw as a carbon source. The isolate, named YB-1301, was identified as Bacillus safensis on the basis of its DNA gyrase subunit B gene (gyrB) sequence. The xylanase productivity of strain YB-1301 was drastically increased when it was grown in the presence of wheat bran or various xylans. In particular, the maximum xylanase productivity reached above 340 U/ml in the culture filtrate from LB broth supplemented with only birchwood xylan at shake-flask level. The xylanase production was significantly induced by xylans at the stationary growth phase in LB medium containing xylan, whereas only a small amount of xylanase was constitutively produced from cells grown in LB medium with no addition of xylan. Furthermore, xylanase biosynthesis was induced more rapidly by the enzymatically hydrolyzed products of xylan than by the non-hydrolyzed xylan. In addition, the xylanase in the culture filtrate of B. safensis YB-1301 was found to have optimal activity at 55℃ and pH 6.5–7.0.

• Applied Biological Chemistry
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• v.48 no.4
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• pp.311-314
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• 2005

Approximately twelve hundred strains of Actonomycetes isolated from domestic soli were tested for their ability to produce extracellular phytase. Of all these isolates a strain, YB-26, that had the highest potential for phytase activity was chosen. The nucleotide sequence of 16S rDNA of the isolate YB-26 showed the highest similarity to that of strains beloning to genus Streptomyces. The partially purified extracellular phytase was obtained from the culture filtrate of Streptomyces sp. YB-26 grown on GSM broth by ammonium sulfate precipitation (15-70%), DEAE-Sepharose column and Q-Sepharose column chromatography. The partially purified enzyme showed the maximum activity for hydrolysis of phyate at $60^{\circ}C$ and pH 7.0, and retained 90% of its maximum activity at the range of pH $6.0{\sim}8.0$. It was thermolabile and its thermostability did not increase in the presence of calcium chloride.

• Microbiology and Biotechnology Letters
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• v.40 no.4
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• pp.296-302
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• 2012

A bacterial strain was isolated from soybean paste fermented in a Korean Buddhist temple as a producer of the extracellular thermostable ${\alpha}$-amylase. The isolate YB-1234 has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. A gene encoding the thermostable ${\alpha}$-amylase of B. licheniformis YB-1234 was cloned into Escherichia coli and its nucleotide sequence was determined. The deduced amino acid sequence of ${\alpha}$-amylase was very highly homologous to those of the thermostable ${\alpha}$-amylases of B. licheniformis belonging to the glycosyl hydrolase family 13. The ${\alpha}$-amylase produced by recombinant E. coli carrying the ${\alpha}$-amylase gene exhibited maximal activity at pH 6.0, identical to ${\alpha}$-amylase in the culture filtrate of B. licheniformis, while the temperature profile was somewhat different between the two. Particularly, ${\alpha}$-amylase produced from B. lcheniformis is much more thermostable than that from recombinant E. coli. The predominant products resulting from the ${\alpha}$-amylase hydrolysis were glucose, maltose and maltotriose for maltotetraose and maltohexaose.

• Environmental Analysis Health and Toxicology
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• v.13 no.3_4
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• pp.55-61
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• 1998

Glutathione-S-transferases (GSTs) detoxify electrophilic xenobiotics and reactive metabolites. Recently benzene-fused heterocycles have been shown to increase the total amount of hepatic GSTs in rats. Primarily this study aimed to determine the induction of GSTs by benzoazoles (BAs) including benzoxazole (BX), 2-methylbenzoxazole (M-BX), 2,5-dimethyl benzoxazole (D-BX), benzothiazole (BT), aminobenzothiazole (A-BT) and 2-mercaptobenzothiazole (M-BT) in rats. Hepatic cytosol and poly(A)$^+$ mRNA were prepared from rats after oral administration of BX, BT, M-BX, D-BX, A-BT and M-BT for 5 consecutive days at doses of 1 mmol/kg. Western immunoblot and northern blot analysis were conducted with rabbit anti-GST Ya, Yb$_1$, Yb$_2$, Yc antibodies and cDNA probes containing = 500 bps in the specific coding regions of Ya, Yb$_1$, Yb$_2$, Yc$_1$, and Yc$_2$, respectively. All BAs increased the amount of enzymes and mRNA levels of GSTs. BT was the most effective inducer of GSTs among the compounds examined in this study. Although A-BT and M-BT, the derivatives of BT, induced GSTs, these chemicals had lesser effect on induction of GSTs than BT. The derivatives of BX also induced less GSTs than the parent compound and the addition of methyl group to the benzene ring of BX reduced the induction of GSTs. BAs had better inductive effects on the class $\alpha$(Ya, Yc) than class $\mu$ GSTs (Yb$_1$, Yb$_2$). BAs enhanced mRNA levels of GSTs in parallel with the protein levels. These results indicate that 1) most of BAs induced various isozymes of GSTs, 2) the induction of GSTs appears to be correlated with the chemical structure of the derivatives, and 3) the expression of GST by BAs is presumably under the transcriptional regulation.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.818-823
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• 1992

2-Ethylhexanoate compounds which contained Y, Er, Yb, Ba, and Cu were prepared separately. These metallo-organic compounds were dissolved together in the common solvent and the solution was homogeneous. From these solution, high $T_c$ superconductors $YBa_2Cu_3O_{7-\delta}(Y_{123})$, $ErBa_2Cu_3O_{7-\delta}(Er_{123})$, and $YbBa_2Cu_3O_{7-\delta}(Yb_{123})$ were prepared. XRD analysis showed that these superconductors were not single phase and contained some impurity phases including $YBa_2Cu_4O_8(Y_{124})$. This was also confirmed from the magnetic susceptibility measurement. Generally, critical temperatures were higher than that of the superconductors prepared by ceramic method. Volume diamagnetic susceptibility showed little variation compared to the specimen made by ceramic method.