• Journal of Microbiology and Biotechnology
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• v.24 no.7
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• pp.969-978
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• 2014

The aprE2 gene with its prosequence from Bacillus subtilis CH3-5 was overexpressed in Escherichia coli BL21(DE3) by using plasmid pET26b(+). After IPTG induction, active and mature AprE2 was produced when cells were grown at $20^{\circ}C$, whereas inactive and insoluble enzyme was produced in a large amount when cells were grown at $37^{\circ}C$. The insoluble fraction was resuspended with 6 M guanidine-HCl and dialyzed against 2 M Tris-HCl (pH 7.0) or 0.5 M sodium acetate (pH 7.0) buffer. Then active AprE2 was regenerated and purified by a Ni-NTA column. Purified AprE2 from the soluble fraction had a specific activity of $1,069.4{\pm}42.4U/mg$ protein, higher than that from the renatured insoluble fraction. However, more active AprE2 was obtained by renaturation of the insoluble fraction. AprE2 was most stable at pH 7 and $40^{\circ}C$, respectively. The fibrinolytic activity of AprE2 was inhibited by PMSF, but not by EDTA and metal ions. AprE2 degraded $A{\alpha}$ and $B{\beta}$ chains of fibrinogen quickly, but not the ${\gamma}$-chain. AprE2 exhibited the highest specificity for N-succinyl-Ala-Ala-Pro-Phe-pNA. The $K_m$ and $k_{cat}/K_m$ of AprE2 was 0.56 mM and $3.10{\times}10^4S^{-1}M^{-1}$, respectively.

• Journal of the Korean Chemical Society
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• v.39 no.12
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• pp.925-931
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• 1995

Urea sensors, prepared by immobilizing urease on ammonium-selective membrane electrodes doped with nonactin, can show interference from several ionic species present in blood samples (e.g., sodium, potassium, and endogenous ammonium ions). This interference problem does not arise from the immobilized biocatalytic reaction but rather from the innate response of the base transducer to ionic species in the sample. In this work, the use of calibrators containing adequate amounts of ionic species is examined to reduce errors caused by endogenous ionic interferences with blood urea measurements. Simultaneous measurements of the interfering species with additional sensors and subsequent substractions of these values from the urea electrode signals are also described. It is shown that the use of a potassium-selective electrode with an adequate calibrator system greatly enhances the accuracy of the urea sensor measurements.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1845-1850
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• 2012

Layered metal hydroxides (LMHs) containing calcium were synthesized by coprecipitation in solution having two different trivalent metal ions, iron and aluminum. Two mixed metal solutions ($Ca^{2+}/Al^{3+}$ and $Ca^{2+}/Fe^{3+}$ = 2/1) were added to sodium hydroxide solution and the final pH was adjusted to ~11.5 and ~13 for CaAl-and CaFe-LMHs. Powder X-ray diffraction (XRD) for the two LMH samples showed well developed ($00l$) diffractions indicating 2-dimensional crystal structure of the synthesized LMHs. Rietveld refinement of the X-ray diffraction pattern, the local structure analysis through X-ray absorption spectroscopy, and thermal analysis also confirmed that the synthesized precipitates show typical structure of LMHs. The chemical formulae, $Ca_{2.04}Al_1(OH)_6(NO_3){\cdot}5.25H_2O$ and $Ca_{2.01}Fe_1(OH)_6(NO_3){\cdot}4.75H_2O$ were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Particle morphology and thermal behavior for the synthesized LMHs were examined by field emission scanning electron microscopy and thermogravimetricdifferential scanning calorimetry.

• Korean Journal of Materials Research
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• v.15 no.12
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• pp.756-759
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• 2005

A lead free piezoelectric material, bismuth sodium barium titanate $(Bi_{0.5}Na_{0.5})_{0.94}Ba_{0.06}TiO_3$ (BNBT), was considered as an environment-friendly alternatives for the current PZT system. A perovskite BNBT was synthesized by conventional bulk ceramic processing technique. In order to improve piezoelectric properties, $La_2O_3$ as a dopant was incorporated into the BNBT system up to 0.025 moi, ana the effects on subsequent the piezoelectric ana dielectric properties were systematically investigated. With increasing $La_2O_3$ contents, the equilibrium grain shape was remarkably evidenced and sintered density was increased. Piezoelectric and dielectric properties were s]town to have maximum values at the $La_2O_3$ contents of 0.02 mol. $La^{3+}$ ions seemed to act as a softener in the BNBT system and to enhance dielectric and piezoelectric properties in this study.

• Resources Recycling
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• v.4 no.3
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• pp.2-9
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• 1995

The rccoverg and separation pracess of nikcl, vanadium and molybdenum from spent dcsulfilrizing catalyst ofpetrochemical rndustries was studied. Tnis process was canied out wet process which is consist of roasting, ammonialeaching and solve111 exDaction techniqcs. The metal ions of NI, V and Mo as vduable compollents were treated byroasting them a1 low lernperatuc, 400$^{\circ}$C in first dep, and then dlssah'ed nu1 at 80$^{\circ}$C wlth ammonium cabonate mlulion.Aftcr cooling them a1 room tempertaure, vanadium wa rccavered from mathcr iiquur in thc f n m of precipitate, sodiumvanadales The Secand slep, roasting the catalyst which is added sodium carbonate ul IOOO"C, was employed. Leachingwith distilled ~ a l e rga ve a iwo phase resultant, solutio~c~a ntaning Ni, V and Mo and solid residue containing sibca,alurmniu~n and iron. A solvcnt exlclction technique uslng vvriuus extractanls, MSP-8, TOIUC, LIX64Pi was eflecnve farthc extraclion and scparation ol thrcc mcfals from thc ammonical 11qou1 thc ammonical 11qou1.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.25-34
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• 2012

It has been well known that concrete structures exposed to acid and sulfate environments such as sewer etc. show significant decrease in their durability due to chemical attack. Such deleterious acid and sulfate attacks lead to expansion and cracking in concrete, and thus, eventually result in damage to cement mortar by forming expansive hydration products due to the reaction between cement hydration products and acid and sulfate ions. In this study, the effect of fly ash and blast furnace slag on the bond performances of structural synthetic fiber in latex modified cement mortar under sulfate environments. Fly ash and blast furnace slag contents ranging from 0 % to 20 % are used in the mix proportions. The latex modified cement mortar specimens were immersed in fresh water, 8 % sodium sulfate ($Na_2SO_4$) solutions for 28 and 50 days, respectively. Pullout tests are conducted to measure the bond performance of structural synthetic fiber from latex modified cement mortar after sulfate environments exposure. Test results are found that the incorporation of fly ash and blast furnace slag can effectively enhance the PVA fiber-latex modified cement mortar interfacial bond properties (bond behavior, bond strength and interface toughness) after sulfate environments exposure. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results under sulfate environments.

• Preventive Nutrition and Food Science
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• v.9 no.3
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• pp.283-288
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• 2004

Superoxide dismutase (SOD) from tomato (Lycopersicon esculentum Mill.) fruit was purified by ammonium sulphate precipitation, Sephadex G-100 and DEAE-cellulose column chromatographies. A 22 fold purification and an overall yield of 44% were achieved. The purified enzyme was a homodimer with Mr 37.1 kDa and subunit Mr 18.2 kDa as judged by SDS-PAGE. SOD showed $K_{m}$ values of 25 ${\times}$ 10$^{-6}$ M and 1.7 ${\times}$ 10$^{-6}$ M for nitroblue tetrazolium (NBT) and riboflavin as substrates, respectively. The enzyme was thermostable upto 5$0^{\circ}C$ and exhibited pH optima of 7.8. The effect of metal ions and some other compounds on enzyme activity was studied. $Co^{2+}$ and $Mg^{2+}$ were found to enhance relative enzyme activities by 27 % and 73 %, respectively, while M $n^{2+}$ inhibited the SOD activity by 64%. However, $Ca^{2+}$ and C $u^{2+}$ had no effect on enzyme activity. Other compounds like $H_2O$$_2$ and Na $N_3$ inhibited enzymatic activities by 60% and 32%, respectively, while sodium dodecyl sulphate (SDS), chloroform plus ethanol and $\beta$-mercaptoethanol had no effect on the activity of SOD. of SOD.

• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.821-826
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• 2001

Solvent sublation has been studied for the separation and determination of trace Zn(Ⅱ) and Pb(Ⅱ) in water samples. A synergy producing method was utilized to improve the efficiency of extraction in the sublation using an ion-pair of metal-naphth oate {M-(Nph)3- } complexes and tetra-n-butylammonium (TBA+ ) ion. After the M-(Nph)3- complexes were formed by adding 1-naphthoic acid to the sample solution, tetra-n-butylammonium bromide was added in the solution to form the ion-pair. And sodium lauryl sulfate (SLS) was added to make the ion-pair hydrophobic. The ion-pairs of the metal complexes were floated and extracted into methylisobutyl ketone (MIBK) from the aqueous solution by bubbling with nitrogen gas in a flotation cell. Metal ions in MIBK solution were measured by graphite furnace-AAS. Experimental conditions were optimized as follow so. After the pH of a 1.0 L water sample was adjusted to 5.0, 6.0 mL of 0.1 M 1-HNph and 10 mL of 0.03 M TBA-bromide were added to the sample to form ion-pairs, and 2.0 mL of 0.2%(w/v) SLS was added to make the ion-pairs hydrophobic. The solution was bubbled with 30 mL/min N2 gas for 5 minutes in a flotation cell. Linear calibration curves were obtained for the determination of Zn(Ⅱ) and Pb(Ⅱ) in several water samples. Reproducible results of showing a relative standard deviation of < 10% and recoveries of 80-100% could be obtained.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.73-73
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• 2017

Pyroprocessing at KAERI (Korea Atomic Energy Research Institute) consists of pretreatment, electroreduction, electrorefining and electrowinning. SFR (Sodium Fast Reactor) fuel is prepared from the electrowinning process which is composed of LCC (Liquid Cadmium Process) and Cd distillation et al. LCC is an electrochemical process to obtain actinides from spent fuel. In order to recover actinides inert anodes such as carbon material are used, where chlorine gas ($Cl_2$) evolves on the surface of the carbon material. And, stainless steel (SUS) crucible should be installed in large-scale electrowinning system. Therefore, the effect of chlorine on the SUS material needs to be studied. LiCl-KCl-$UCl_3$-$NdCl_3$-$CeCl_3$-$LaCl_3$-$YCl_3$ salt was contained in 2 kinds of electrolytic crucible having an inner diameter of 5cm, made of an insulated alumina and an SUS, respectively. And, three kinds of electrodes such as cathode, anode, reference were used for the electrochemical experiments. Both solid tungsten (W) and LCC were used as cathodes. Cd of 45 g as the cathode material was contained in alumina crucibles for the deposition experiments, where the crucible has an inner diameter of 3 cm. Glassy carbon rod with the diameter of 0.3 cm was employed as an anode, where shroud was not used for the anode. A pyrex tube containing LiCl-KCl-1mol% AgCl and silver (Ag) wire having a diameter of 0.1cm was used as a reference electrode. Electrodeposition experiments were conducted at $500^{\circ}C$ at the current densities of $50{\sim}100mA/cm^2$. In conclusion, Fe ions were produced in the salt during the electrodeposition by the reaction of chlorine evolved from the anode and Fe of the SUS crucible and thereby LCC system using SUS crucible showed very low current efficiencies compared with the system using the insulated alumina crucible. Anode shroud needs to be installed around the glassy carbon not to influence surrounding SUS material.

• Journal of Soil and Groundwater Environment
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• v.26 no.1
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• pp.65-75
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• 2021

We investigated hydrochemical and stable isotope characteristics of groundwater in a large agricultural plain, the Honam plain, to evaluate the adequacy of agricultural water supply. For preliminary assessment for the area, we collected 23 groundwater samples from domestic wells and conducted hydrochemical and water stable isotope analysis. Groundwater in the study area is mainly Ca-HCO3 type resulting from water-rock interactions. Stable oxygen and hydrogen isotopic compositions indicated that recharge water is derived from precipitation while some sampling sites had evaporation signatures. Irrigation water quality using sodium absorption ratio and salinity hazard showed most of the groundwater samples were found to be suitable for irrigation. The groundwater in the southwestern part of the study area was affected by both seawater intrusion and agricultural activities, indicating a higher possibility of groundwater contamination near the coastal areas. Elevated concentrations of nitrate and phosphate ions in the groundwater are considered to be influenced by anthropogenic activities such as fertilizer application. It is expected that this study would be able to provide preliminary information on groundwater quality for agricultural water supply in the Mangyeong-Dongjin watershed.