• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1541-1544
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• 2002

The concentration of B in steels is important due to its influence on mechanical properties of steel such as hardenability, hot workability, and creep resistance. An analytical method has been developed to determine B in steel samples by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). National Institute of Standard and Technology Standard Reference Material (NIST SRM) 348a was analyzed to validate the analytical method. The steel sample was digested in a centrifuge bottle with addition of aqua regia and $^{10}B$ spike isotope. Sample pH was then adjusted to higher than 10 to precipitate most matrix elements such as Fe, Cr, and Ni. After centrifugation, the supernatant solution was passed through a cation exchange column to enhance the matrix separation efficiency. B recovery efficiency was about 37%, while matrix removal efficiency was higher than 99.9% for major matrix elements. The isotope dilution method was used for quantification and the determined B concentration was in good agreement with the certified value.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.4
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• pp.231-233
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• 2002

The potential of calcium peroxide to act as an agent for waterblooming control was In-vestigated by examining the growth inhibition of Microcystis aerusinosa. Due to the chemical nature of calcium peroxide, it can remove dissolved phosphate by forming an Insoluble precipitate, generating radicals, coagulant, and oxygen as byproducts as it dissolves in water. The growth of M. aerusinosa was severely inhibited and the chlorophyll-n concentration was drastically decreased in the presence of calcium peroxide. With 200 ppm of calcium peroxide dosage, a chlorophyll-a concentration of 1,700 mg/m$^3$ was lowered to below 10% of its initial concentration after 4 days. One possible explanation for this growth Inhibition is the removal of the available phosphate by calcium peroxide.

• Applied Microscopy
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• v.43 no.3
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• pp.122-126
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• 2013

The heterogeneous nucleation of the ${\Theta}^{\prime}$ phase on nanoscale precipitates has been investigated using a combination of three-dimensional atom probe tomography and high-resolution transmission electron microscopy. Two types of ${\Theta}^{\prime}$ phases were observed, namely small (~2 nm thick) cylindrical precipitates and larger (~100 nm) globular precipitates and both appear to be heterogeneously nucleated on the nanoscale precipitates. The composition and crystal structure of precipitates were directly analyzed by combination of two advanced characterization techniques.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.365-368
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• 1998

The aklavinone 11-hydroxylase which was overexpressed using T7 promoter in E. coli could be detected in SDS-PAGE only in insoluble precipitate without any detectable enzyme activity. The insoluble enzyme was solubilized in 6M guanidine$.$HCl solution and their refolding ability was tested under various conditions. When the enzymatic activity was checked by the bioconversion experiment, stepwise dialysis against 6M, 3M, 1M guanidine$.$HCl and finally 100 mM potassium phosphate buffer of the solubilized protein gave the best bioconversion efficiency. The aklavinone 11-hydroxylase showed its enzymatic activity in the reaction buffer containing NADPH with vigorous shaking. The enzymatic activity was lost during partial purification and regained by the addition of crude extract of S. lividans in the reaction mixture. This effect was confirmed to due to some low-molecular weight component(s) in the crude extract, because the addition of dialyzed crude extract could not recover the enzymatic activity.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.919-925
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• 2010

The features of precipitating reaction of fluoride have been examined by employing waste gypsum as a precipitant. The major component of waste gypsum was examined to be CaO with minor components of $SO_3$, $SiO_2$. In the experimental condition, the precipitating reaction of fluoride progressed rapidly within a few minutes after the reaction started and reached its equilibrium in 10 minutes. Kinetic analysis showed that the precipitating reaction of fluoride generally followed a first Oder and second Oder with decreasing rate constant with the initial dosage of precipitant. XRD analysis showed that the crystalline structure of precipitate was mainly $CaF_2$ with partly $Ca_5(PO_4)_3(OH)$.

• Journal of Korean Society on Water Environment
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• v.29 no.4
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• pp.497-503
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• 2013

The morphological characteristics of granules, which were generated in lab-scale sequencing batch reactor (SBR) for simultaneous nitrogen and phosphorus removal with denitrifying phosphorus accumulating organism (dPAO) were identified. Granular sludge was fully developed in the anaerobic-anoxic (An-Ax) SBR after 180 days of SBR operation. The average diameter of granular sludge was 2.2 mm and rod-type organisms dominated in the granules. In addition, about 1.0 mm of white precipitate was observed in the core of the granule, and the material was confirmed that it is very similar to hydroxyapatite $(HAP;\;Ca_5(PO_4)_3(OH))$ by X-ray diffraction) analysis.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.477-482
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• 1994

Structural changes of hydrous titania by heat-treatment was investigated with XRD, TEM, FT-IR, Rarnan spectral analyses. The hydrous titania was derived from a mixed solution of titanium tetrachloride and hydrogen peroxide at $30^{\circ}C$ and pH of 9.0. The precipitate was an anatase form of titania with less-developed crystalline structure. With increasing annealing temperature ranglng up to $700^{\circ}C$, the crystallinity of anatase increased, and the particles were grown at high temperature. The rutile form of titania was developed from the anatase at $700^{\circ}C$.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.199-203
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• 2000

A bacterium that produce biopolymer was isolated from Gochujang, one of Korean traditional fermented foods, and identified as Bacillus licheniformis. The production of biopolymer was highest and 34mg/250ml, when the baterium was cultivated in condition of sucrose 6.0%, Yeast extract 0.1%, peptone 0.l%, NaCl 3.0%, and pH 6.0. The 1% solution of this biopolymer was able to form a translucent and glossy film. And the solution of biopolymer was found to precipitate Kaolin solution and also stabilize the suspension of lactic acid bacteria within the test range of 0.25-1.00%. [Bacillus licheniformis, Biopolymer].

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.2 no.1
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• pp.1-8
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• 1998

Biomass of non-living brown seaweed Sargassum fluitans pretreated by different methods is capable of taking up more than $10\%$ (11 meq/g) of its dry weight in aluminum at a pH of 4.5. It is indicated that the biomass sequestered the aluminum in the form of polynuclear aluminum species. The fraction of $Al(OH)_3$ Precipitated in the aluminum nitrate solution without biomass at pH 4.5 increased as the Al concentration increased. Aluminum-alginate complex precipitated in the solution as alginate was partially released from the biomass. External colloidal precipitate occurring in native and protonated S. fluitans biomass sorption systems caused a significant difference in Al sorption isotherms determined by standard and desorption methods, respectively, Sodium ions added for pH adjustment were not sorbed at all in the presence of aluminum ions.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.5
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• pp.226-231
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• 2020

The Cu-Co-Si alloy shows high strength by forming precipitates by aging precipitation heat treatment of supersaturated solid solution treated with solution treatment such as Cu-Ni-Si alloy, and the Co₂Si precipitated phase is dispersed in the copper matrix. The effect of aging treatment on the microstructure, mechanical and electrical properties of Cu-Co-Si alloys for electronic devices was investigated. As a results of SEM/EDS analysis, it was found that Co₂Si precipitates of 30~300 nm size were distributed in grains. By performing the double aging treatment, it was possible to improve the strength and electrical conductivity by dispersing the fine precipitate evenly.