• Journal of Life Science
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• v.13 no.4
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• pp.498-504
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• 2003

This Study was carried out to investigate the optimal mycelial growth of Pholiota nameko. The optimal medium for the mycelial growth was ME medium. The optimal temperature and pH were $25^{\circ}C$$\pm$1 and 5.5, respectively. The modified optimal medium compositions were glucose 3% (w/v), malt extract 0.25% (w/v), yeast extract 0.25% (w/v), $KH_2PO_4$ 0.046% (w/v), $K_2HPO_4$ 0.1% (w/v), $MgSO_4$ㆍ$7H_2O$ 0.05% (w/v). From the result of experiments on the optimal temperature, pH and nutritional requirements, the mycelial growth of modified optimal medium was higher than that of ME medium.

• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.253-263
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• 2016

Fungi, such as the wood-rotting Polyporus brumalis, are excellent sources of pharmaceutically interesting natural products such as sesquiterpenoids. In this study, we investigated the biosynthesis of P. brumalis sesquiterpenoids on modified medium. Ten additional species of white rot fungi were inoculated in medium containing nutrients such as $C_6H_{12}O_6$, $C_4H_{12}N_2O_6$, $KH_2PO_4$, $MgSO_4$, and $CaCl_2$ at $28^{\circ}C$ for 25 days. After 10 days of incubation, eudesmane-type sesquiterpenes, ${\beta}$-eudesmane and ${\beta}$-eudesmol, were only synthesized during the growth phase of P. brumalis. Experiments excluding one nutrient at a time were conducted to determine the effects of inorganic nutrients on sesquiterpene biosynthesis. In conclusion, GC-MS analysis showed that biosynthesis of sesquiterpenes was differentially regulated by inorganic nutrients such as $MgSO_4$, $C_4H_{12}N_2O_6$, and $KH_2PO_4$. We found $MgSO_4$ supplementation to be vital for eudesmane-type sesquiterpene biosynthesis in P. brumalis; nitrogen ($C_4H_{12}N_2O_6$) and phosphate ($KH_2PO_4$) inhibited the synthesis of P. brumalis metabolites. Magnesium is a known cofactor of sesquiterpene synthase, which promotes ${\beta}$-eudesmol synthesis. To mechanistically understand eudesmane-type sesquiterpene biosynthesis in P. brumalis, further research into the genes regulating the dynamics of such biosynthesis is warranted.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.247-251
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• 1989

Effects of mineral salts on sisomicin fermentation were investigated. The optimal concentration of CoCl$_2$for accomplishing a high antibiotic yield was found to be 16.8 $\mu$M at which it could function as a cofactor. At this level the other mineral salts tested had no effect. On the other hand, at much higher concentration levels (above 1 mM), four mineral salts such as ZnSO$_4$, KH$_2$PO$_4$, FeSO$_4$and MgSO$_4$were used in order to liberate the intracellular sisomicin out-side the cells, because the sisomicin accumulated mostly in cells and it was supposed to limit the improvement of antibiotic yield. ZnSO$_4$and KH$_2$PO$_4$had no effect at all, and FeSO$_4$brought about some improvement. However, by keeping the concentration of MgSO$_4$to be 25 mM or higher in culture broths, the antibiotic yield could be improved by more than 100%, partially due to the enhanced liberation of the intracellular antibiotic.

• Corrosion Science and Technology
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• v.15 no.6
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• pp.303-310
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• 2016

The tap water used in Seoul was found to be corrosive. Its corrosivity was effectively reduced by that the additions of alkali agent such as NaOH, $Ca(OH)_2$ and corrosion inhibitor such as $H_3PO_4$. For the corrosion test, carbon steel pipe 50 m long was exposed to the drinking water produced by a pilot plant at $36.5^{\circ}C$, similar to the existing process where it takes about 20 minutes to reduce the initial chlorine content of 0.5 mg/L to 0.05 mg/L. $CO_2$ and $Ca(OH)_2$ was added not only to control the Langelier index (LI) above -1.0 and but also, to increase the duration time of residual chlorine by about 6 times. The persistence effect of residual chlorine was in the order of $H_3PO_4$ > $Ca(OH)_2$ > NaOH. Measurements of weight loss showed that corrosion inhibition was effective in order of $Ca(OH)_2$ > $H_3PO_4$ > NaOH > no addition, where the concentrations of $Ca(OH)_2$ and phosphate were 5 ~ 10 mg/L (as $Ca^{2+}$) and 1 mg/L (as $PO{_4}^{3-}$), respectively.

• Current Research on Agriculture and Life Sciences
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• v.6
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• pp.99-104
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• 1988

Water polution status of urban streams in Daegu city were observed to provide the basic information for the effective purification of urban sewage and the conservation of Keumho river. Periodically, pH, DO, COD, nitrate and phosphate of water were investigated at Yee cheon, B$\ddot{o}$m$\ddot{o}$ cheon, Chilsung cheon, Dalseo cheon and Kongdan cheon. The results were as follows. 1) The ranges of average values of analyzed components for 12 months at six sampling sites were pH 7.3-8.2, DO trace-6.5ppm, COD 20.4-116.9ppm, T-N 23.2-31.7ppm, $NH_4$-N 18.3-27.7ppm, $NO_2$-N 0.08-1.89ppm, $NO_3$-N 0.19-1.51ppm, $PO_4$-P 2.50-17.28ppm. 2) At Kongdan cheon, the most heavily polluted site, average values of components were pH 8.2, DO trace, COD 116.9ppm, T-N 23.2ppm, $NH_4$-N 18.3ppm, $NO_2$-N 1.89ppm, $NO_3$-N 1.51ppm, $PO_4$-P 17.28ppm. 3) The values of pH, DO, COD, T-N and $NH_4$-N at winter urban streams were higher than those at summer urban streams. And the values of $NO_2$-N and $PO_4$-P were more or less higher at summer urban streams.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.78-86
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• 2004

In order to reveal the relationship between the concentration of chlorophyll- a and the environmental factors affecting eutrophication, the present study was biweekly conducted at G stations in the lower part of the Han river during the period from Feb. 24,2001 to Feb. 9,2002. Water temperature was changed from $0.5^{\circ}C$ to $26.4^{\circ}C$, pH was 5.77${\sim}$8.99, DO 3.15${\sim}$14,36 mg $L^{-1}$, BOD 0.90${\sim}$7.45 mg $L^{-1}$, and COD 1.16${\sim}$9.13 mg $L^{-1}$. TN and TP were ranged from 1.68${\sim}$20.96 mg $L^{-1}$, and 0.02 ${\sim}$ 1.17 mg $L^{-1}$, respectively. $NH_4\;^+$-N, $NO_3\;^-$-N, and $PO_4\;^{3-}$-P were ranged from 0.56${\sim}$3.60 mg $L^{-1}$, 0.03${\sim}$7.29 mg $L^{-1}$, and 0.002${\sim}$0.754 mg $L^{-1}$. Chlorophyll- a was extensively changed from 2.29 ${\mu}g\;L^{-1}$ to 136.28 ${\mu}g\;L^{-1}$ by month and stations. Results of nutrients indicated the eutrophic level in this area and water quality was the gradual worsening in the lower stations than those of upper stations during the period studied. The Pearson correlation analysis between the concentration of chlorophyll- a and the environmental factors indicated that BOD, COD, pH, $NH_4\;^+$-N, TP, TN, conductivity and $PO_4\;^{3-}$-P were positive correlation, but $NO_3\;^-$-N was negative. The environmental factors investigated using the principal component method could be triparted. The first factor group included conductivity, BOD, COD, TN, TP, $NH_4\;^+$-N, $PO_4\;^{3-}$-P and SS, the second WT and DO, and the third pH and $NO_3\;^-$-N. Using the stepwise regression analysis, chlorophyll- a was under the influence of conductivity, $PO_4\;^{3-}$-P, $>NO_3\;^-$-N and $NH_4\;^+$-N Chlorophyll-a = 0.3661 ${\times}$ (Conductivity) - 0.3592 ${\times}$ ($PO_4\;^{3-}$-P) - 0.3449 ${\times}$ ($NO_3\;^-$-N)+0.4362 ${\times}$ ($NH_4\;^+$-N.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.921-928
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• 2004

Calcium phosphate powders have been prepared by using $Ca(OH)_2\;and\;H_{3}PO_4$ solution under various conditions such as pH, calcination temperature, and reaction time. ${\beta}-TCP({\beta}-tricalcium phosphate)$and HAp(hydroxyapatite) were synthesized at pH=5.21 and pH > 7.62, respectively. From XRD results, $Ca(OH)_2\;and\;H_{3}PO_4$ solution reacted quickly to form HAp, which was structurally stable up to 16h. Calcination temperature having good crystallinity is revealed to be at $1200^{\circ}C$. SEM analysis showed that ${\beta}-TCP$ and HAp with needle type were synthesized at pH 5.21 and pH 7.62, respectively. However, at pH 9.16, tiny and homogeneous HAp having sphere was prepared and rearranged to show needle morphology. HAp synthesized at pH 9.16 was utilized as bonechina body and calcined. The sample was analyzed its crystallinity, water absorbtion, color, and shape to check physical properties.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2025-2028
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• 2014

Anion receptor 1 based on acylhydrazone has been designed and synthesized. UV-vis and $^1H$ NMR titration showed that receptor 1 is selective receptor for dihydrogen phosphate ($H_2PO_4{^-}$). Dihydrogen phosphate was complexed by the receptor 1 via at least 4 hydrogen bonding interactions, contributing from two amide N-Hs and two imine C-Hs. In addition, nitrogen in the aromatic ring could make 2 additional hydrogen bondings with OH groups in the dihydrogen phosphate. However, the receptor 1 could make only 4 hydrogen bonds with halides. Therefore, receptor 1 could bind anions through hydrogen bonds with a selectivity in the order of $H_2PO_4{^-}$ > $Br^-$ > $Cl^-$ in highly polar solvent such as DMSO.

• The Korean Journal of Mycology
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• v.17 no.3
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• pp.149-153
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• 1989

One strain of Aspergillus niger K-25 producing an acid-stable ${\alpha}-amylase$ was isolated from the soil. The optimum culture conditions were investigated. The production of the acid-stable ${\alpha}-amylase$ was enhanced when the strain was incubated in a medium containing soluble starch 3.5%, peptone 2%, $KH_2PO_4$ 0.5%, $MaSO_4{\cdot}7H_2O$ 0.25% and $FeCI_3$ 1.0% at pH 3 for 7 days. However, higher activity of acid-stable ${\alpha}-amylase$ was demonstrated on wheat bran culture. Amylase production was doubled when A. niger K-25 was incubated on the wheat bran supplemented with fumaric acid buffer (pH 3).

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2174-2181
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• 2024

In this work, Sr_0.5Zr₂(PO₄)₃-SmPO₄ dual-phase ceramics were prepared via in-situ synthesis process, which is a potential novel nuclear waste form for immobilizing the fission product ⁹⁰Sr and the trivalent actinide radionuclides in high-level waste (HLW). And the preparation technology, microstructure and chemical durability of Sr_0.5Zr₂(PO₄)₃-SmPO₄ dual-phase ceramics were systematically investigated. It was confirmed that the optimum microwave-sintering temperature (1050 ℃) and heat preservation time (1.5 h) is estimated by Archimedes method. Besides, the as-prepared samples that were consisted of strontium zirconium phosphate (SrZP) and monazite showed the remarkable densification, in which the two crystalline phases were intermixed well with each other. Meanwhile, the formation and evolution of microstructure was also consistent with the variational rule of Sr_0.5Zr₂(PO₄)₃/SmPO₄, indicating that there was not mutual reaction during the in-situ synthesis process. The PCT and MCC-1 experimental results demonstrated that the elemental normalized leaching rates of tested samples are all at a low level (LR_Sr ~10^-4 g·m^-2·d^-1, LR_Zr ~10^-8-10^-6 g·m^-2·d^-1, LR_Sm ~10^-7-10^-5 g·m^-2·d^-1 and LR_P ~10^-4 g·m^-2·d^-1). It is indicated that Sr_0.5Zr₂(PO₄)₃-SmPO₄ dual-phase ceramics possesses excellent chemical durability for HLW disposal.