• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1030-1035
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• 1998

The porous alumina membrane was prepared from aluminum metal(99.8%) by anodic oxidation using DC power supply of constant current mode in an aqueous solution of sulfuric acid. To prevent the chemical dissolution of alumina membrane, $Al_2(SO_4)_3$, $AlPO_4$ and $Al(NO_3)_3$ which could be considered to supply $Al^{3+}$ ions were added to electrolyte solution at a reaction temperature of $20^{\circ}C$ and cumulative charge of $150C/cm^2$. Effects of these additives on the formation of porous alumina membrane were evaluated under various electrolyte concentration(5~20 wt%) and current densities($10{\sim}50mA/cm^2$). The membrane surfaces which were prepared in electrolyte solution with all the additives except $Al_2(SO_4)_3$ were damaged. However, when $Al_2(SO_4)_3$ was added to the $H_2SO_4$ solution, an uniform surface of porous alumina was obtained. Also, it was shown that the pore size of membrane was nearly independent on the quantity of $Al_2(SO_4)_3$ added at same electrolyte concentration and current density.

• Applied Biological Chemistry
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• v.41 no.1
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• pp.6-12
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• 1998

To extract insoluble proteins and to improve functional properties of abolished proteins, a protease producing Aspergillus sp. MS-18 was isolated from soil. The enzyme was purified and its enzymological characteristics were investigated. It was found that production of protease reached to the maximum when the wheat brae medium containing, 3% arabinose, 0.5% polypepton, 0.1% $(NH_4)_2SO_4$ and 0.2% magnesium chloride was cultured for 3 days. Protease was purified 16.9 folds after ion exchange chromatography and gel filtration and the specific activity was 340.4 unit/mg. Purified enzyme was confirmed as a single band by the polyacrylamide gel electrophoresis. The molecular weight of protease was estimated to be 30,000. Crystalization form of purified protease was a stick shape with rounding edges. The optimum pH and temperature for the protease activity were 9.0 and $60^{\circ}C$, respectively. The enzyme was stable in pH 7.0-12.0 at $50^{\circ}C$. The activity of purified enzyme was inhibited by $Hg^{2+}$, $Cu^{2+}$, $Zn^{2+}$ and $Pb^{2+}$, whereas it was activited by $Na^+$, $Mg^{2+}$ and $Mn^{2+}$. The activity of the protease was inhibited by the treatment with ethylenediaminetetraacetic acid and phenylmethane sulfonyl fluoride. The result suggests that the purified enzyme is a serine protease with metal ion at active site. Km and Vmax of purified protease were $29.33\;{\mu}mole/L$ and $5.13\;{\mu}g/min$, respectively.

• Applied Biological Chemistry
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• v.18 no.3
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• pp.177-182
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• 1975

The analysis of Jerusalem artichoke showed that it contains 12.09% of Inulin. The results obtained from the examination of the conditions for fructose production by cultivating Pencillum sp 1 in the Jerusalem articoke medium were as follows: 1. The optimum amount of water added to Jerusalem artichoke was 2.5 $\ell$ of distilled water per ㎏ of fresh Jerusalem artichoke. It this case, the concentration of Inulin was 4% (w/v). 2. The optimum temperature was $30^{\circ}C$, the initial optimum pH was 5.0 and the optimum cultural period was 72 hours. 3. Shaking culture with 50 ml of the medium and 120 oscills/min in 500 ml shaking flask was most effective as the culture method. 4. 0.1% of $NH_4H_2PO_4$ as a nitrogen source, 0.001 of $FeSO_47H_20$ and 0.001% of $MgSO_47H_2$ as metal salts were most effective. 5. Fructose production continued to increase for 72 hours under the optimum conditions for cultivation and the highest production rate to the Inulin was 95.25%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.3
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• pp.138-146
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• 1989

This experiment was conducted to utilize the water soluble protein from the fish meal in wastewater as nitrogen source by alkaline protease producting bacteria and to investigate the culture condition of the production. G-12 and G-14 strains having the strong activity of the alkaline pretense were isolated from sea water. These strains were identified as Pseudomonas chlororaphis and Pseudomonas alcaligenes according to physiologycal characteristics, respectively. In enzyme production, galactose and casein for G-12 strain, and raffinose and the water soluble protein of the fish meal wastewater for G-14 strain was favorable as carbon and nitrogen source. An action of inhibition appeared in all of the metal salts used. The optimal temperature of enzyme production was $30^{\circ}C$ for all strains. Optimal initial pH for the enzyme formation in G-12 and G-14 strains was pH 10.0 and 8.0. When these two strains were incubated for $30\~35$ hours in the optimal production medium, the enzyme production reached at maximum.

• Microbiology and Biotechnology Letters
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• v.4 no.3
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• pp.91-97
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• 1976

During the course of studies on the production and utilization of thermostable ${\alpha}$-amylase from a thormophilic actinomycete species isolated from soil, partial characterization of the ${\alpha}$-amylase has been (arried out. The optimum pH for the dextrinogenic activity of the enzyme was found to be 6.5 and the maximum reaction rate was achieved at a temperature range of 55$^{\circ}$ to 65$^{\circ}C$. Calcium ion was recognized to have a slight effect in activating the enzyme, while heavy metal salts especially ferrous and cupric ions showed a remarkable inhibition effect. The enzyme was best protected iron thermal denaturation at pH 8.0 with tris-HCI buffer；inactivation was rapid at higher or lower pH values. Furthermore, its thermal stability was greatly increased by calcium ion, particulary at the final concentration of 1${\times}$10$\^$－2/ mole in the reaction mixture. The Km value for the ${\alpha}$-amylase was calculated to be 2.17${\times}$10$\^$－4/g per $m\ell$ and the energy of activation for the dextrinogenic reaction to be 12,000${\pm}$580 ㎈ per mole.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.142-150
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• 2002

Streptomyces polychromogenes IFO 13072 was used as a strain producing cholesterol oxidase(EC 1.1.3.6). The conditions of cholesterol oxidase production were investigated. The optimum composition of medium for production of the enzyme was 1% dextrin, 0.5% casamino acid, 0.1% $KH_2$PO$_4$, 0.5% $NaNO_3$ and 0.05% $MgSO_4$(pH 7.3). The enzyme was purified specifically by cholesterol affinity column chromatography with a yield of 23.2%. The purified enzyme showed a single polypeptide on SDS-PAGE and the molecular weight was estimated about 52,000 daltons. The optimum pH and temperature of the cholesterol oxidase were pH 7.0 and $37^{\circ}C$, respectively. The enzyme was stable in the range of pH 6.0~7.0 and $25^{\circ}C$. The cholesterol oxidase activity was strongly inhibited by metal ions such as $Hg^{2＋}$ and $Fe^{2＋}$ and inhibitors such as dithiothreitol, mercaptoethanol and isonicotinic acid. The Michaelis constant(Km) for the cholesterol was found to be 25 mM by Lineweaver-Burk plot analysis.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.987-996
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• 2009

Aspergillus niger GH1 previously isolated and identified by our group as a wild tannase producer was grown under solid-state (SSC) and submerged culture (SmC) conditions to select the enzyme production system. For tannase purification, extracellular tannase was produced under SSC using polyurethane foam as the inert support. Tannase was purified to apparent homogeneity by ultrafiltration, anion-exchange chromatography, and gel filtration that led to a purified enzyme with a specific activity of 238.14 IU/mg protein with a final yield of 0.3% and a purification fold of 46. Three bands were found on the SDS-PAG with molecular masses of 50, 75, and 100 kDa. PI of 3.5 and 7.1% N-glycosylation were noted. Temperature and pH optima were 600e and 6.0 [methyl 3,4,5-trihydroxybenzoate (MTB) as substrate], respectively. Tannase was found with a $K_M$ value of $0.41{\times}10^{-4}M$ and the value of $V_{max}$ was $11.03{\mu}$moL/min at $60^{\circ}C$ for MTB. Effects of several metal salts, solvents, surfactants, and typical enzyme inhibitors on tannase activity were evaluated to establish the novelty of the enzyme. Finally, the tannase from A. niger GH1 was significantly inhibited by PMSF (phenylmethylsulfonyl fluoride), and therefore, it is possible to consider the presence of a serine or cysteine residue in the catalytic site.

• Environmental Engineering Research
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• v.25 no.1
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• pp.88-95
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• 2020

An investigation of rare metals recovery from LiNi_xCo_yMn_zO₂ cathode material of the end-of-life lithium-ion batteries is presented. To determine the influence of reductant on the leach process, the cathode material (containing Li 7.6%, Co 20.4%, Mn 19.4%, and Ni 19.3%) was leached in H₂SO₄ solutions either with or without H₂O₂. The optimal process parameters with respect to acid concentration, addition dosage of H₂O₂, temperature, and the leaching time were found to be 2.0 M H₂SO₄, 4 vol.% H₂O₂, 70℃, and 150 min, respectively. The yield of metal values in the leach liquor was > 99%. The leach liquor was subsequently treated by precipitation techniques to recover nickel as Ni(C₄H₇N₂O₂)₂ and lithium as Li₂CO₃ with stoichiometric ratios of 2:1 and 1.2:1 of dimethylglyoxime:Ni and Na₂CO₃:Li, respectively. Cobalt was recovered by solvent extraction following a 3-stage process using Na-Cyanex 272 at pH_eq ~5.0 with an organic-to-aqueous phase ratio (O/A) of 2/3. The loaded organic phase was stripped with 2.0 M H₂SO₄ at an O/A ratio of 8/1 to yield a solution of 114 g/L CoSO₄; finally recovered CoSO₄.xH₂O by crystallization. The process economics were analyzed and found to be viable with a margin of $476 per ton of the cathode material.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.327-331
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• 2010

Porcine placenta was treated with alkali, acid and enzyme treatment to obtain extracts. Heavy metal contents such as Pb, As, and Hg were low enough to satisfy cosmetic agent standard. As a result of safety test(MTT assay), porcine placenta extracts showed over 80% of cell viability at $50{\mu}g/ml$, and cell toxicity was relatively lower. From antioxidation test using DPPH free radical scavenging assay, antioxidation effect was highest as 63% at $50{\mu}g/ml$ when porcine placenta was treated with alkali in pH 9. From whitening effect test using tyrosinase inhibition assay, tyrosinase inhibition effect was 30% at $50{\mu}g/ml$ concentration in alkali treated procine placenta, however, the efficiency was lower compared with arbutin or vitamin C. In anti-wrinkle effect test from elastase inhibition assay, elastase inhibition effects were 20~30% at $50{\mu}g/ml$ for 5 kinds of porcine placenta treatments, which was superior to standard, and especially, protease treated extracts showed best results. Skin formulation including 1% porcine placenta was made and the formulation was very stable for temperature and storage period. From this research, porcine placenta extract showed high potential for anti-wrinkle functional cosmetic agent.

• Resources Recycling
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• v.9 no.1
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• pp.52-62
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• 2000

In order to maximize the recycling of converter slag to the more valuable fields, such as high quality aggregates for construction, cement industry and flux for ion making. It will be very important to control the compositions and properties of converter slag to suit the purpose of utilizastion. In this study, converter slag (STELCO, CANADA) was mixed with 5%~30% $SiO_2$and 7% carbon, and then reduced at $1650^{\circ}C$. After the reduction was completed, the reformed slags were cooled to room temperature in the furnace. All of the slags were then characterized using SEM-EDX, XRD and chemical analysis. Also the compressive strengths and densities of the reformed slags were measured to compare with natural aggregates. XRD analysis shows that th phases of reformed slags are changed from bredigite+merwinite mixed phases of 10% $SiO_2$added reduction to akermanite phases of 20% and 30% $SiO_2$ added reduction. But the SEM-EDX analysis revealed that the phase distribution of the reformed slags was changed very sensitively and complicately depends on the change of slag compositions. And also the properties of reformed slags are changed very much depend on the phase distribution. About one third of Cadmium and on fifth of Vanadium are remained in reduction reformed converter slag. Another heavy metal elements such as cobalt, zinc, lead are removed up to more than 90-95% of original slag. The compressive strength and density of 25% $SiO_2$ added and reformed slag is very near to natural granite. This is superior more than 10% to Thyssen's $SiO_2$ added and oxidized converter slag aggregates.