• Polymer(Korea)
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• v.39 no.3
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• pp.394-402
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• 2015

Modification of polyacrylonitrile (PAN) films by using hydroxylamine (HA) and hydrazine to produce hydroxyl and amine groups, respectively, and to introduce cross-linking of PAN polymers was studied. Modified PAN films obtained by HA and/or hydrazine treatment including a successive or a simultaneous process were analyzed by the degree of conversion, water and N,N'-dimethylformamide (DMF) swelling ratio, FTIR spectra, atom content, and thermal analysis data. PAN films reacted with HA showed increased hydrophilicity and low dimensional stability in water. Hydrazine treatment gave PAN films high dimensional stability of low DMF swelling. Although the DMF swelling ratio of the modified PAN films was dramatically decreased by the successive treatment of hydrazine and HA, the introduction of the hydrophilic functional groups was limited due to the cross-linking. Simultaneous treatment of HA and hydrazine was the most effective method to increase hydrophilicity of PAN films with a high dimensional stability.

• Journal of Sensor Science and Technology
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• v.3 no.2
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• pp.3-10
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• 1994

The use of preformed polymers and their cross-linking has been attempted in order to improve the intrinsic fragility of monolayers and Langmuir-Blodgett(LB) films. The evaluation of the characteristics of the LB multi-layer by using an AT-cut quartz crystal has been also attempted. This study reveals that the polyether pendants of 2C18VE3 lie at the air-water interface at low surface pressures and are forced down into the subphase when the monolayers are compressed. This characteristic behavoir of the pendant polyethers is very clear on aqueous poly allyl amine(PAA) and is also observeable on saturated aqueous NaCl and $CaCl_{2}$. And the characteristics of LB multi-layers could be evaluated by using AT-cut quartz crystal in situ.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.123-128
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• 2004

Quantum chemical quantities, enthalpy of formation(${\Delta}H_f$), HOMO and LUMO energy, and dipole moment(${\mu}_D$) were acquired by AM1, PM3, and ZINDO/1 methods for polyamines and imidazole derivatives. The investigation of the inhibitory activity on some Ni(II) complexes with polyamines and imidazole derivatives is performed by ZINDO/1 calculations. It was found that experimental inhibitory activity(IA) appeared when the value of net charge and enthalpy of formation were over 0.03 and -300 eV, respectively for Ni(II) complexes. These results showed that the Ni(II) complexes have exception on the following very unstable compounds: square pyramidal [Ni(dpt)(tn)])]$^{2+}$(dpt=3,3'-diaminodipropylamine)(tn=1,3-diaminopropane) and distorted tetrahedral [Ni(N-PropIm))$_2$(NCS))$_2$](N-PropIm=N-Propylimidazole).

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.6
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• pp.437-444
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• 2003

Objective of this experiment was to investigate the role of strontium in intracellular processes in mung bean (Vigna radiata L.). Diamine oxidase (DAO) induction by $Sr^{2+}$ appeared to a decrease in putrescine levels correspondently. DAO activities in the hypocotyls were in a range of 0.5 to $1.8unit{\cdot}mg^{-1}\;protein{\cdot}min^{-1}$. The decrease in Put levels in the cotyledons might be partly resulted from Put degradation by DAO. It was observed that the accumulation of spermidine and spermine by $Sr^{2+}$ was in the range of 1 mM to 10 mM. Spermidine levels were 2 to 3 fold higher than in the absence of strontium. The increase in polyamine levels was observed not only on a basis of g fresh weight but also a RNA basis. These results demonstrated that the inhibitory action of $Sr^{2+}$ may be closely related with polyamine metabolism as well as diamine oxidation and polyamine accumulation.

• Membrane Journal
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• v.27 no.5
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• pp.449-457
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• 2017

In this study, the 10 stages stacked module was designed by increasing the number of unit cells in the membrane capacitive deionization(MCDI) process. The aminated polysulfone and sulfonated poly(ether ether ketone) were synthesized and coated on porous carbon electrode by casting method. The salt removal efficiency was measured for the 10 stage stacked module under the operation conditions of adsorption voltage and time, desorption voltage and time, flow rate and concentration of feed water, and di-valent solutions including $CaSO_4$, $MgCl_2$ and tap water. Typically, when 100 mg/L of NaCl as the feed was used, the salt removal efficiency was 98.3% at a flow rate of 100 mL/min, the adsorption condition of 1.2 V/3 min and desorption condition of -0.5 V/5 min.

• Membrane Journal
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• v.28 no.5
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• pp.326-331
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• 2018

Crosslinking of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) anion exchange membranes, which can be used for capacitive deionization (CDI), was investigated. PPO Anion exchange polymer was prepared through bromination and amination reaction steps and crosslinked with bisphenol A diglycidylether (BADGE), m-phenylenediamine (m-PDA), and hexamethylenediamine (HMDA). The gelation time by crosslinking was short in the order of HMDA > m-PDA > BADGE. The anion exchange membranes crosslinked at room temperature over a certain amount of crosslinking agent did not dissolve in an aprotic solvent such as 1-methylpyrrolidone (NMP) and the chemical durability of their membranes to organic solvent increased. The ion exchange capacity and water uptake of anion exchange membranes crosslinked with different crosslinker (BADGE) contents were measured and compared. The CDI performance of the crosslinked PPO anion exchange membrane immersed in the HMDA solution was almost the same as that of the non - crosslinked membrane except for the initial stage of the adsorption step.

• Polymer(Korea)
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• v.37 no.5
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• pp.618-624
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• 2013

Hydroquinone bis(trimellitic anhydride) (HQ-TA) was synthesized from trimellitic anhydride chloride and hydroquinone. Poly(amic acid)s (PAAs) were synthesized by reacting a HQ-TA with six different diamines, which were cyclized to yield polyimides (PIs) containing ester linkages by chemical- and thermal-imidization methods. The various PIs were synthesized from structurally different aromatic diamines. The glass transition temperatures ($T_g$) were in the range of 167-$215^{\circ}C$, and the decomposition temperatures (${T_D}^i$) were in the range of $364-451^{\circ}C$. The maximum improvements in coefficient of thermal expansion (CTE) and barrier to oxygen permeation were observed in PIs using TFB (3.23 $ppm/^{\circ}C$) and 4,4-ODA (< $10^{-2}cc/m^2/day$), respectively. The PI films possessed a transmittance of 65-89% at 500 nm and had a yellowish color with a yellow index (YI) of 3.01-69.52.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.300-305
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• 2009

We constructed the deletion mutants of fission yeast Schizosaccharomyces pombe spNab2 gene that is homologous to poly(A)-binding protein NAB2 in budding yeast Saccharomyces cerevisiae, which plays crucial roles in mRNA 3' end formation and mRNA export from nucleus into the cytoplasm. A null mutant in an $h^+$/ $h^+$ diploid strain was constructed by replacing the spNab2-coding region with an $ura4^+$ gene using one-step gene disruption method. Tetrad analysis showed that the spNab2 is not essential for vegetative growth and mRNA export. However, over-expression of spNab2 cause the severe growth defects and intensive accumulation of poly(A) RNA in the nucleus. Also, the spNab2-GFP fusions were localized mainly in the nucleus. These results suggest that spNab2 is also involved in mRNA export out of the nucleus.

• Membrane Journal
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• v.25 no.6
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• pp.547-557
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• 2015

In this study, we synthesized polyimide with high carbon dioxide gas transport property using 2,2-bis(3,4-carboxylphenyl) hexafluoropropane, 2,3,5,6-tetramethyl-1,4-phenylenediamine and poly(ethylene glycol) bis(3-aminopropyl) terminated and then we calculated solubility parameter of synthesized polymer and non-solvent phase separation coefficient to determine proper solvent for preparation of asymmetric membrane, also we measured the viscosity of the polymer solution to check polymer contents in membrane solution and prepare asymmetric membrane with $LiNO_3$ additives. The morphology and gas separation property of membrane prepared by phase separation method was confirmed using Field Emission Scanning Electron Microsope and the single gas permeation measurement apparatus. We confirmed that the carbon dioxide permeance of the membrane increased and the selectivity showed little change with decreasing of the volatile solvent contents.

• Polymer(Korea)
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• v.34 no.3
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• pp.198-201
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• 2010

We have worked a surface modification to release a strong agglomeration of multi-walled carbon nanotube(MWCNT) and a incorporation of hydrophilic polymer to improve compatibility between MWCNT and polymers. Carboxylated MWCNT was easily obtained by acid treatment and the carboxylate was converted to acylchloride by thionyl chloride. Then, we tried one more synthesizing routes to achieve covalent bonds with poly(ethylene oxide) having amine end groups of low molecular weight. We measured the polymer content on the surface of MWCNT by TGA and observed increased diameter of MWCNT by SEM and TEM analysis.