• BMB Reports
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• v.29 no.2
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• pp.99-104
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• 1996

Site-directed substitutions were made to change the Ile91 of restriction endonuclease EcoRV to either Val, Ala or Gly to identify the role of Ile91 in recognition and catalysis, since substitution of Ile91 with Leu afforded dramatic effects on the activity and properties of restriction endonuclease EcoRV. These changes alter the size of the hydrophobic side chain at position 91 and thus might have revealed the reason for the altered phenotype of Ile91Leu. However, the properties of Ile91Val and Ile91Ala mutants were much like wild type EcoRV, in both activity and metal ion preference. Ile91Gly had very little activity with either $Mg^{2+}$ or $Mn^{2+}$ as cofactors. To try to understand the unusual $Mn^{2+}$ profile of the Ile91Leu mutant, two double mutants, Ile91Leu;Asp90Asn and Ile91Leu;Glu45Met were created. Both double mutants were seriously disabled by the second amino acid change. Ile91Leu;Glu45Met had some residual activity in the $Mn^{2+}$ reaction buffer, whereas the Ile91Leu;Asp90Asn displayed no detectable activity.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.4
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• pp.113-120
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• 2006

Wastewater generated through the food waste recycling process have known high concentration, BOD 20,000~150,000 mg/L, which has to treat to the proper level because of a ban on reclamation. But it is impossible to treat less than 10 days by existing water treatment plant. Ecodays Ltd. is to treat this wastewater during 2~4 days by ER-1, which can simultaneously induce the modified PFR(Plug Flow Reactor) of the oxygen transfer rate, MLVSS concentration, and influent concentration to top from bottom of reactor. We tested the pilot test about low concentration food wastewater(BOD 16,500 mg/L) and high concentration food wastewater(64,431 mg/L) at the food waste recycling plant of H-Gun(20t/d). Hydraulic retention time(HRT) of ER-1 for low concentration food wastewater is 2.5day. In low concentration conditions, ER-1 treatment efficiency is to appear BOD 99%, COD 98%, TN 97%, and TP 96%. While ER-1 process for high concentration food wastewater treatment is composed 2 stages, which are to be HRT 2.5day for law wastewater and HRT 1.5 day for secondary treatment. In high concentration conditions, ER-1 treatment efficiency is to appear BOD 97%, COD 84%, TN 66%, and TP 95%. It is treated without temperature control about high temperature($50^{\circ}C$) to appear low treatment efficiency in high concentration conditions.

• Korean Journal of Veterinary Research
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• v.39 no.1
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• pp.90-95
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• 1999

A species-specific 760 base pair(bp) BamHI to EcoRI DNA fragment(fMG-2) of lipoprotein gene was isolated from a Mycoplasma gallisepticum(M gallisepticum) genomic library. Based on the DNA sequence data of fMG-2, a pair of 25bp primers was synthesized. When used in the polymerase chain reaction(PCR), 732bp DNA products were amplified from 6 standard strains and 10 field isolates of M gallisepticum, but not from 2 Mycoplasma synoviae and 7 other Mycoplasma species. The lower detection limit was 100fg of the genomic DNA. Identity of the PCR products was confirmed by comparison of patterns of restriction endonuclease analysis with AseI, DraI, EcoRV and SspI.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.1
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• pp.58-63
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• 2010

Mg and Ma-based alloys are promising hydrogen storage materials for renewable clean energy applications. It has high hydrogen storage capacity (7.6wt.%), lightweight and low economical materials. However, commercial applications of the Mg hydride are currently hindered by its high operating temperature, and very slow reaction kinetics. In this work, we are aimed at studying the hydrogenation properties of the $MgH_x-V_2O_5$ composite prepared by hydrogen induced mechanical alloying. The absorption capacity of the sample is found to be about 4.7wt.% at 623K under 3 MPa $H_2$ pressure. The absorption characteristics observed have been compared with prepared $MgH_x$.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.12
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• pp.1129-1134
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• 2009

Increasing application of nanotechnology highlights the need to clarify nanotoxity and nanoparticles characterization. However, few researches have focused on phytotoxicity of nanoparticles. This study was to examine phytotoxicity on Cumumis sativus seedling and the dissolution of Zn, ZnO nanoparticles in hydroponic culture system. Results of this study; characteristics of Zn, ZnO nanoparticles are more aggregated in nutrient solution than deionized water. C. sativus biomass significantly reduced in the nutrient solution were higher than 100 mg/L, and Zn toxicity showed $Zn^{2+}$> Zn> ZnO NPs. Results of transmission electron microscopy images, Zn and ZnO nanoparticles greatly adhered onto the root cell wall and nanoparticles were observed in the root cell.

• Journal of Microbiology and Biotechnology
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• v.21 no.5
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• pp.503-508
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• 2011

A ${\beta}$-glucosidase from Phoma sp. KCTC11825BP isolated from rotten mandarin peel was purified 8.5-fold with a specific activity of 84.5 U/mg protein. The purified enzyme had a molecular mass of 440 kDa with a subunit of 110 kDa. The partial amino acid sequence of the purified ${\beta}$-glucosidase evidenced high homology with the fungal ${\beta}$- glucosidases belonging to glycosyl hydrolase family 3. Its optimal activity was detected at pH 4.5 and $60^{\circ}C$, and the enzyme had a half-life of 53 h at $60^{\circ}C$. The $K_m$ values for p-nitrophenyl-${\beta}$-D-glucopyranoside and cellobiose were 0.3 mM and 3.2 mM, respectively. The enzyme was competitively inhibited by both glucose ($K_i$=1.7 mM) and glucono-${\delta}$-lactone ($K_i$=0.1 mM) when pNPG was used as the substrate. Its activity was inhibited by 41% by 10 mM $Cu^{2+}$ and stimulated by 20% by 10 mM $Mg^{2+}$.

• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1264-1270
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• 2012

The ecotoxicological effects of nanomaterials on animal, plant, and soil microorganisms have been widely investigated; however, the nanotoxic effects of plant-soil interactive systems are still largely unknown. In the present study, the effects of ZnO nanoparticles (NPs) on the soil-plant interactive system were estimated. The growth of plant seedlings in the presence of different concentrations of ZnO NPs within microcosm soil (M) and natural soil (NS) was compared. Changes in dehydrogenase activity (DHA) and soil bacterial community diversity were estimated based on the microcosm with plants (M+P) and microcosm without plants (M-P) in different concentrations of ZnO NPs treatment. The shoot growth of M+P and NS+P was significantly inhibited by 24% and 31.5% relative to the control at a ZnO NPs concentration of 1,000 mg/kg. The DHA levels decreased following increased ZnO NPs concentration. Specifically, these levels were significantly reduced from 100 mg/kg in M-P and only 1,000 mg/kg in M+P. Different clustering groups of M+P and M-P were observed in the principal component analysis (PCA). Therefore, the M-P's soil bacterial population may have more toxic effects at a high dose of ZnO NPs than M+P's. The plant and activation of soil bacteria in the M+P may have a less toxic interactive effect on each of the soil bacterial populations and plant growth by the ZnO NPs attachment or absorption of plant roots surface. The soil-plant interactive system might help decrease the toxic effects of ZnO NPs on the rhizobacteria population.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.3
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• pp.130-138
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• 2022

In this study, the characteristic of an amorphous fishing weight material according to controlling the alloy type and alloy composition of the glass forming agent added in PbO₂ oxide was investigated. According to the experimental, when the glass forming agent of 15wt%SiO₂-1wt%MgO content was added in β-PbO₂, an amorphous fishing weight substitute having the lowest friction coefficient, excellent corrosion resistance and durability was obtained. The cell number of PbO₂-15wt%SiO₂-1wt%MgO sample incubated in cell culture fluid tended to hardly decrease even after a lapse of 24 hours, It means that the fabricated PbO₂-15wt%SiO₂-1wt%MgO sample is significantly less-toxic and harmless to the human body, unlikely to metallic lead. It is considered that an fabricated amorphous fishing weight substitute proved to have a potential as an eco-friendly material with little marine pollution.

• Korean Journal of Materials Research
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• v.34 no.5
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• pp.254-260
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• 2024

This study is to manufacture a titanium dioxide (TiO₂) photocatalyst by recycling sludge generated using titanium tetrachloride (TiCl₄) as a coagulant. Compared to general sewage, a TiCl₄ coagulant was applied to dyeing wastewater containing a large amount of non-degradable organic compounds to evaluate its performance. Then the generated sludge was dried and fired to prepare a photocatalyst (TFS). Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), and nitrogen oxide reduction experiments were conducted to analyze the surface properties and evaluate the photoactive ability of the prepared TFS. After using titanium tetrachloride (TiCl₄) as a coagulant in the dyeing wastewater, the water quality characteristics were measured at 84 mg/L of chemical oxygen demand (COD), 10 mg/L of T-N, and 0.9 mg/L of T-P to satisfy the discharge water quality standards. The surface properties of the TFS were investigated and the anatase crystal structure was observed. It was confirmed that the ratio of Ti and O, the main components of TiO₂, accounted for more than 90 %. As a result of the nitric oxide (NO) reduction experiment, 1.56 uMol of NO was reduced to confirm a removal rate of 20.60 %. This is judged to be a photocatalytic performance similar to that of the existing P-25. Therefore, by applying TiCl₄ to the dyeing wastewater, it is possible to solve the problems of the existing coagulant and to reduce the amount of carbon dioxide generated, using an eco-friendly sludge treatment method. In addition, it is believed that environmental and economic advantages can be obtained by manufacturing TiO₂ at an eco-friendly and lower cost than before.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.10
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• pp.1466-1472
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• 2012

A bacterial isolate derived from soil samples near a cattle farm was found to display extracellular phytase activity. Based on 16S rRNA sequence analysis, the strain was named Bacillus sp. T4. The optimum temperature for the phytase activity toward magnesium phytate (Mg-$InsP_6$) was $40^{\circ}C$ without 5 mM $Ca^{2+}$ and $50^{\circ}C$ with 5 mM $Ca^{2+}$. T4 phytase had a characteristic bi-hump two pH optima of 6.0 to 6.5 and 7.4 for Mg-$InsP_6$. The enzyme showed higher specificity for Mg-$InsP_6$ than sodium phytate (Na-$InsP_6$). Its activity was fairly inhibited by EDTA, $Cu^{2+}$, $Mn^{2+}$, $Co^{2+}$, $Ba^{2+}$ and $Zn^{2+}$. T4 phytase may have great potential for use as an eco-friendly feed additive to enhance the nutritive quality of phytate and reduce phosphorus pollution.