• Journal of Photoscience
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• 제12권1호
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• pp.47-50
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• 2005

Mediumeffects have been explored on the competitive H-atom abstraction and SET-promoted, silyl-transfer reactions of excited states of silylalkyl-substituted phenyl ketones. The chemical selectivities of photochemical reactions of silylalkyl phenyl ketones appear to depend on medium polarity, medium silophilicity, added metal cation and alkyl length. Irradiations of silylalkylketones in aqueous solvent system and in presence of metal cation such as $Li^+$ and $Mg^{+2} $lead to formation of acetophenone predominantly by the sequential SET-silyl transfer route.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 추계학술논문요약집
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• pp.345-346
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• 2017

• 한국재료학회지
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• 제34권5호
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• pp.247-253
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• 2024

The separation of zirconium and hafnium using tributyl phosphate (TBP)-Dodecane extractants in nitric acid medium was performed. Zirconium oxychloride, used as extraction feed, was obtained from the synthesis of Kalimantan zircon sand concentrate smelted using NaOH. The extraction process was carried out by dissolving chloride-based metals in nitric acid media in the presence of sodium nitrate using TBP-Dodecane as an extractant. Some of the extraction parameters carried out in this study include variations in organic phase and aqueous phase (O/A), variations in contact time, and variations in nitric acid concentration. Extraction was carried out using a mechanical shaker according to the parameter conditions. X-ray fluorescence (XRF) was used for elemental (Zr and Hf) composition analysis of the aqueous solution. The results showed that zirconium was separated from hafnium at optimum conditions with an organic/aqueous ratio of 1:5, contact time of 75 min, and an HNO₃ concentration of 7 M. The resulting separation factor of zirconium and hafnium using TBP-Dodecane was 14.4887.

• 한국염색가공학회지
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• 제24권3호
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• pp.165-172
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• 2012

The stability of yellow and red dyes prepared from safflower (Carthamus tinctorius L.) in aqueous solution and in solid state was investigated. External factors such as light irradiation and temperature on the stability were examined during storage. Changes in absorbance of dye solutions and the color changes of fabrics dyed after long time storage were measured. Also, color reproducibility during storage was investigated by dyeing test on various fabrics. Red colorant in aqueous solution was very unstable to light, resulting that about 40% of absorbance were lost in 12hrs. The absorbance of yellow dye solutions was not decreased within 84hrs. In aqueous medium, yellow dye was much more stable than carthamin. Both dyes are relatively stable for long storage when they are stored in solid state compared to when in aqueous solution. Color changes are marginal in both dyes.

• Journal of Microbiology and Biotechnology
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• 제9권5호
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• pp.589-592
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• 1999

Suspension cultures of Digitalis lanata were successfully performed in an aqueous two-phase system (ATPS) of 4.5％ polyethylene glycol (PEG) 20,000 and 2.8％ crude dextran. Cell growth in the medium containing an individual ATPS-forming polymer was inhibited due to the toxicity of PEG and a high viscosity of dextran. Formation of ATPS supported cell growth by showing a considerably decrease in viscosity and partitioning of cells into a PEG-lean dextran phase. It was found that an aqueous two-phase cultivation of plant cells in a stirred tank bioreactor could be successfully applied.

• Journal of Applied Biological Chemistry
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• 제61권4호
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• pp.383-389
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• 2018

Degradation of the insecticide O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate (chlorpyrifos) in aqueous solution was investigated using iron salts and potassium persulfate during ZVI treatment through a series of batch experiments. The degradation rate of chlorpyrifos increased with increases in the concentrations of iron salts and potassium persulfate in the aqueous system. Ferric chloride was found to be the most effective iron salt for the ZVI-mediated degradation of chlorpyrifos in aqueous solution. Further, the iron salts tested could be arranged in the following order in terms of their effectiveness: $FeCl_3$> $Fe_2(SO_4)_3$> $Fe(NO_3)_3$. The persulfate-ZVI system could significantly degrade chlorpyrifos present in the aqueous medium. This revealed that chlorpyrifos degradation by treatment with $Fe^0$ was promoted on adding ferric chloride and potassium persulfate. The kinetics of the degradation of chlorpyrifos by persulfate-amended $Fe^0$ was higher than that for iron-salt-amended $Fe^0$. This suggests that using a sequential $Fe^0$ reduction-ferric chloride or $Fe^0$ reduction-persulfate process may be an effective strategy to enhance the removal of chlorpyrifos in contaminated water.

• 펄프종이기술
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• 제47권4호
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• pp.76-80
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• 2015

In filler loaded paper, the size of the filler affects its strength, optical and surface properties. As the size of the filler increases, tensile strength and bulk usually increases, opacity decreases, and smoothness becomes worse. Pre-flocculation of GCC (grounded calcium carbonate) makes large diameter flocs at aqueous medium that consists of multiple GCC particles, but they collapse to 2-dimensional shape in dried paper and makes low bulk paper. The hybrid calcium carbonate (HCC) that was made by in-situ $CaCO_3$ formation between GCC in aqueous medium made high bulk paper without harming tensile strength, bulk, opacity, and smoothness. The GCC that has equivalent size as HCC failed to make high opacity and smoothness as much as HCC.

• Macromolecular Research
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• 제12권2호
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• pp.240-245
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• 2004

Monodisperse PMMA micro spheres are prepared by means of a simple soap-free emulsion polymerization in methanol-enriched aqueous medium in a single step process. The size and uniformity of the microspheres are dependent on the polymerization temperature. In a stable system, the uniformity is improved with the polymerization time. The most uniform and stable micro spheres are obtained under mild agitation speed of 100 rpm at 70$^{\circ}C$. The monodisperse PMMA microspheres in the size range of 1.4-2.0 $\mu\textrm{m}$ having less than 5% size variation are successfully achieved with varying concentrations of monomer and initiator. As the monomer and initiator concentrations increase, the larger micro spheres with enhanced uniformity are obtained. However, the decreased amount of water induces the polydisperse PMMA particles due to the generation of secondary particles.

• 대한화학회지
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• 제12권3호
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• pp.114-120
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• 1968

Fe-EDTA complex, which is easily formed when Fe salt and EDTA.2Na are mixed in the aqueous medium, is found to be a very effective catalyst in the dehydropolycondensation of aminophenols. In the dehydropolycondensation of aminophenols, the catalyst, Fe(Ⅲ)-EDTA complex (higher oxidation state) is reduced to less stable Fe(Ⅱ)-EDTA complex (lower oxidation state), and the latter is easily oxidized by air to the original higher oxidation state complex, therefore the catalytic action of Fe-EDTA complex is found to be recycled effectively. Under the catalytic action of the above mentioned complex, p-aminophenol is polymerized in the aqueous medium to form the oligomers of p-aminophenol, which the degree of polymerization to be 5 or more. The oligomers formed contain partly quinone nucleus as well as amino and hydroxyl groups. In this study, the effects of the solvents and characteristics of the oligomers are discussed. These types of polymerizations catalyzed by the metallic chelate compounds are considered to be very closely related to the reactions in the living matters.

• Environmental Engineering Research
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• 제11권6호
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• pp.318-324
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• 2006

The higher valence state of iron i.e., Fe(VI) was employed for the oxidation of one of an important toxic ion, cyanide in the aqueous medium. Cyanide was oxidized into cyanate, which is 1,000 times less toxic to cyanide and often accepted for its ultimate disposal. It was to be noted that Fe(VI) is a very powerful oxidizing agent and can oxidize most of the cyanide within few minutes i.e., ca 5 mins of contact. The data was obtained by the UV-Visible measurements for the Fe(VI) decomposition. The UV-Visible data was used to evaluate the overall rate constant for second order redox reaction between ferrate(VI) and cyanide. Also the pseudo first order rate constant was calculated as keeping the cyanide concentration in excess.