• Applied Chemistry for Engineering
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• v.8 no.1
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• pp.140-145
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• 1997

Carbon dioxide hydrogenation reaction was carried out over hybrid catalyst composed of $Cu/ZnO/ZrO_2$, and MFI zeolites such as HZSM-5, H-Ga-Silicate and H-Fe-Silicate. The hybrid catalyst composed of $Cu/ZnO/ZrO_2$, catalyst and HZSM-5 showed the highest yield and selectivity to $C_2{^+}$ hydrocarbon, which seemed to be due to the largest amount of Br nsted acid sites. Higher yield to $C_2{^+}$ hydrocarbon was obtained over HZSM-5 with lower $SiO_2/Al_2O_3$ ratio and also with longer ion exchange time, which showed larger amount of Br nsted acid sites, respectively. When a metal ion was exchanged into HZSM-5, the highest yield to $C_2{^+}$ hydrocarbon was obtained with descending order $Ga/HZSM-5{\simeq}HZSM-5>Zn/HZSM-5$, i.e., with the amount of $Br\ddot{o}nsted$ acid sites.

• The Journal of Korean Medicine
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• v.22 no.2
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• pp.53-63
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• 2001

This study was carried out to investigate the physiological activityof the water extract from EA. The present study was done to investigate the effects of EA on cultured hepatocyte cell system and lipid peroxidation in $A{\beta}$ treatment conditions. Pretreatment of EA attenuated in cell cytotoxicity enhanced by increasing concentrations of $A{\beta}$. MDA level induced by $A{\beta}$ treatment was significantly increased and the level was slightly reduced by pretreatment of EA. The ability of EA to reduce cell death and MDA level induced by $A{\beta}$ suggest that EA may be a protective agent against free radical generating compounds such as $A{\beta}$. EA exhibited anti oxidative activity at all concentration tested.The extract was as good as antioxidative activity of the synthetic antioxidants, butylated hydroxy toluene and ascorbic acid. Furthermore, this was superior to that of natural antioxidant, a-tocopherol. In the presence of heavy metal ions ($Fe^{2+},{\;}Zn^{2+}$), EA showed strong antioxidative activity. The extracts showed about 3075% in the nitrite scavenging effect under pH 1.2 and $37^{\circ}C$ for 1 hr. There was significant difference among concentration of extracts.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.564-570
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• 1995

N-Benzoyl-L-aspartyl-L-phenylalanine methyl ester(BzAPM), a novel aspartame precursor, was investigated for its enzymatic synthesis by immobilized thermolysin using a water-miscible organic solvent system. The substrate used were N-benzoyl-L-aspartic acid(BzAsp) and L-phenylalanine methyl ester (PheOMe). Synthetic conditions such as substrates concentration, temperature, pH, and some metallic ions were varied to study their effects on BzAPM synthesis. The synthetic reaction rate increased linearly as the PheOMe concentration increased at a constant concentration of BzAsp(100 mM), and the maximum reaction rate was obtained at BzAsp concentration of 200 mM when 300 mM PheOMe was used. The optimum pH and temperature were found to be 6.1 and $40^{\circ}C$, respectively. The metallic ions such as $Zn^{2+},\;Mg^{2+},\;Mn^{2+},\;Fe^{2+},\;Pb^{2+}\;and\;Cu^{2+}$ at 5 mM level showed inhibitory effect on BzAPM synthesis, while $Co^{2+}$ and $Ca^{2+}$ ion increased synthesis. $Co^{2+}$ ion was also found to have synergistic effect with $Ca^{2+}$ ion. Benzoic acid, L-phenylalanin and NaCl showed inhibitory effect.

• Korean Journal of Environmental Biology
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• v.19 no.3
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• pp.211-217
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• 2001

Salicylate is involved in the induction of pathogen-related proteins and plant defense response. The effects of salicylate on the activity isoperoxidase $A_3$ from tobacco callus (Nicotiana tabacum L.) and the protection against the enzyme inactivation by salicylate in the presence of $Fe^{2+}$ were examined. About 20% and 85% activity losses of peroxidase occurred at 0.48 mM and 0.6 mM salicylate, respectively, showing that isoperoxidase $A_3$ was inactivated by salicylate. The inactivation occurred depending on pH and showed noncompetitive inhibition mode. Moreover, inactivation of the enzyme by salicylate was completely protected in the presence of $Fe^{2+}$. Apoperoxidase without heme moiety was constructed and the effects of various metal ions on the recovery of enzyme activities were investigated. More than 80% of the activity was reconstituted by the addition of $Fe^{2+}$ or hemin. However, the enzyme activity was not recovered by $Cu^{2+},\;Zn^{2+},\;Co^{2+},\;or\;Mn^{2+}$.

• Journal of the Korean GEO-environmental Society
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• v.8 no.2
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• pp.5-9
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• 2007

This study carried out to investigate the removal capacity of heavy metals such as Cu (II), Zn (II) and Cd (II) dissolved in aqueous solution in the soils collected from Hyeon-Dong (HD), San-seong (SS), Keum-chon (KC) and Keum-Hac (KH) located in the upper Banbyun stream. The pH of all the soils was weak alkali such as 8.8 9.2. According to the analysis of chemical composition of the soils, the amount of $SiO_2$, $AlO_2$ and CaO were similar in all tested soils. However, the amount of $K_2O$, $FeO_3$ and MgO were different from each soil. The XRD measurement with these soils showed that quartz and feldspar were presented in all tested soils, and the distribution of kaoline, illite, montmorillonite, vermiculite and calcite were different from each soil. The results of the removal capacity of heavy metals indicated that all the soils had more than 98% of the removal efficiency of Cu (II), Zn (II) and Cd (II), and among the heavy metals, Cu (II) was removed the most effectively. These results suggested that the soils collected from the upper Banbyun stream have the high removal capacity of heavy metals, and these soils could be used for the banking a river around the abandoned mine area, containing the higher concentrations of heavy metals than the usual stream.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.2
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• pp.23-33
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• 1991

Mn - Zn Ferrite has the natural characteristics of incongruent melting and the zinc oxide evaporation while the crystal is being grown. As a result of these, it comes into existence to be a non-uniform distribution of cations along the crystal growth axis and also Pt particles are usually precipitated into the crystals in Bridgman method since the melt zone is maintained for a long time in the crucible. These have bad effects on the magnetic properties of ferrites. But, to overcome these faults and then acquire the better single crystals. new modified growth method was developed and the growth factors were investigated as following: melt height in the crucible, surface tension and density of melt, the behavior of melt at interface, the shapes of crucible and solid -liquid interface, powder feeding rate, and the crystal growing speed. In additon, when we analyzed the compositional fluctuations of grown crystals, they were supressed within 1.5 mol% $Fe_20_3$, 2 mol% MnO, ZnO respectively with comparing to initial composition of crystal and the microstructures of crystals on the(110) plane were observed by optical microscope through the chemical etching technique and the magnetic properties were determined.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.177-183
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• 1985

Some properties of an extracellular cytosine deaminase produced from Arthrobacter sp.JH-13 were examined after 20-80% of ammonium sulfate fractionation. Among some substrates, this enzyme utilized cytosine and 5-fluorocytosine as a substrate. The optimum pH and temperature for the activity of this enzyme were found to be near 8.0 and $40^{\circ}C$, respectively. The ensyme was more stable in 0.2M of Tris-HCl buffer than 0.2M of potassium phosphate buffer. The enzyme was generally stable below $50^{\circ}C$, but inactivated completely at $70^{\circ}C$. 1mM of $Fe^{3+},\;K^+\;and\;Na^+$ increased the enzyme activity, but 0.01mM of $Co^{2+},\;Cu^{2+},\;Ni^{2+},\;Hg^{2+},\;Ag^{2+},\;Zn^{2+},\;Ba^{2+},\;and\;Mg^{2+}$ markedly inactivated the enzyme activity. 0.1mM of p-chloromercuribenzoate, trichloroacetic acid, and N-ethylmaleimide compleyely inhibited the enzyme activity, but 0.1mM of 2-mercaptoethanol slightly increased the enzyme activity.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.4
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• pp.229-236
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• 2003

This pot experiment was conducted in order to observe the effects of application of combined micronutrients(T$_1$: control. T$_2$; Fe, T$_3$; Fe+Mn, T$_4$； Fe＋Mn＋Cu, T$_{5}$; Fe+Mn+Cu＋Zn, T$_{6}$；Fe+Mn+Cu＋Zn+Mo, T$_{7}$； Fe+Mn+Cu+Zn+Mo+B) on forage performance of pure and mixed cultures of orchardgrass and white clover. The first part was concerned with the changes in the growth, summer depression, and flowering of forage plants. The results obtained are summarized as follows: 1. The T$_3$and T$_{6}$ resulted in a wide chlorosis induced by the Fe-deficiency on orchardgrass. Chlorosis was significantly reduced by the T$_4$and T$_{5}$, whereas the T$_{7}$, T$_2$, and T$_1$showed normal growth without chlorosis symptoms. The T$_{7}$ resulted in the best growth of orchardgrass both in the pure and mixed swards. There was no chlorosis symptom on white clover. whereas the T$_1$, T$_2$and T$_{7}$ showed a relatively good growth with deep green leaf-colour compared with the other treatments in the pure culture. 2. In summer, a summer depression occurred in orchardgrass: this was significantly reduced by the T$_1$and T$_{7}$. The treatments with chlorosis symptoms in orchardgrass partly induced a lodging. Summer depression in white clover did not occur. 3. In the pure culture, the T$_{7}$ and T$_2$in white clover resulted in many flowers and flower-buds compared with the other treatments. The T$_{7}$, especially, showed a long blooming period and an early full bloom compared with the other treatments, whereas the T$_{6}$ and is showed inferior numbers of them. Only the T$_{7}$ resulted in more flowers than flower-buds, and above 1 in the flower/flower-bud ratio except the T$_{6}$ in the mixed culture. 4. It was recognized that the chlorosis of Fe-deficiency occurred not only from the unsuitable ratios of Fe/Mn and Fe/Mo but also from the unsuitable mutual ratios among the cations(Fe, Mn, Cu and Mn), between the anions(Mo and B), and their total ion concentration. It was observed the multiple interactions of Fe${\times}$Mn${\times}$Mo${\times}$B, and the distinct role of B as a regulator.

• Journal of Life Science
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• v.13 no.5
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• pp.618-625
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• 2003

Investigations were carried out to optimize the culture conditions for the production of xylanase by Paenibacillus sp. DG-22, a moderately thermophilic bacterium isolated from timber yard soil. Xylanase production showed a cell growth associated profile. Xylanase activity was found only in the culture supernatant, while $\beta-xylosidase$ activity was mainly associated with the cells. The formation of xylanase activity was induced by xylan and repressed by glucose and xylose. The production profile of xylanase was examined with various commercial xylan and maximum yield was achieved with 0.1∼ 0.5% birchwood xylan. Among various nitrogen sources tested, yeast extract was optimal for the production of xylanase. The xylanase activity was inhibited by $Co^{2+},\; Cu^{2+},\; Fe^{3+},\; Hg^{2+}\;$ and$\;Mn^{2+}$ ions while $Ca^{2+},\; Mg^{2+},\; Ni^{2+},\; Zn^{2+}$ions and DTT stimulated xylanase activity Mercury (II) ion at 5 mM concentration abolished all the xylanase activity. The predominant products of xylan-hydrolysate were xylobiose, xylotriose, and higher xylooligo-saccharides, indicating that the enzyme was an endoxylanase.

• Journal of environmental and Sanitary engineering
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• v.24 no.1
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• pp.33-39
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• 2009

In order to investigate effect of metal ion and antioxidant on rancidity of crude rapeseed oil (CRO), $Fe^{2+}$, $Cu^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cr^{2+}$, $Sn^{2+}$, $Mn^{2+}$, $Zn^{2+}$, and antioxidants including BHA, Vitamin C, and Tocopherol were used. The specific gravity and refractive index of CRO were $0.92g/cm^3$ and 1.45, respectively. The chromaticities of light, red, and yellow in CRO were 88.6 and 98.7, respectively. Among various fatty acids, Oleic acid (C18:1) concentration was highest, 62.3% and Linoleic acid (C18:2) concentration was 19.16%. In the case of Linolenic acid (C18:3) and Palmitic acid (C16:0), they were 9.88 and 5.2%, respectively. The concentrations of unsaturated fatty acids and saturated fatty acid were 92.2 and 7.8%, respectively. The degree of expediting rancidity of CRO was an order of $Fe^{2+}$> $Cu^{2+}$> $Cr^{2+}$> $Zn^{2+}$> $Ni^{2+}$> $Al^{2+}$> $Mn^{2+}$> $Mn^{2+}$> $Sn^{2+}$> $Co^{2+}$> $Li^{2+}$. Especially, when $Cu^{2+}$ and $Fe^{2+}$ was used, the peroxide value concentration was about 4.0 fold higher than non addition of them. The inhibition effect of rancidity of CRO using antioxidant with $Cu^{2+}$ and $Fe^{2+}$ was an order of BHA> Vitamin C> Tocopherol.