• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.34-39
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• 2010

Methacryloxypropyltrimethoxysilane (MPTMS) was used for the surface modification of silica nanoparticles in the toluene dispersion system for 8 h (MPSN). Then, methacryloxypropyl-modified silica nanoparticles were successfully prepared by solutioun polymerization in the ethanol solution at $60^{\circ}C$ for 14 h with adding AIBN initiator. The modification of ultra-fine particles (SiOx-PAA nanospheres) was investigated via EA, XPS, FTIR, TGA, SEM and TEM. The mean diameter of the bare silica nanoparticles, MPSN and SiOx-PAA monodisperse nanoparticles was about 25, 30 and 35 nm, respectively.

• Polymer(Korea)
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• v.32 no.4
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• pp.305-312
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• 2008

A novel TPC-PEG-TPC with active end-groups was obtained from the end-groups of polyethylene glycol (PEG) modified by terephthaloyl chloride (TPC). These active end-groups can link up with a rare earth ion, which is a luminescent center of a rare earth fluorescent complex. Complexes of Eu-PEG with novel ligands (TPC-PEG-PTC) were synthesized by the coordination of the active reactant (as the first ligand) and phenanthroline (as the second ligand) with $Eu^{3+}$.IR, $^1H$-NMR, element analysis, DSC, WAXD, fluorescent spectroscopy, TGA, and SEM were used to characterize the structure and properties of these complexes. The results showed that this type of complex is a heat storage material with the phase change character of polyethylene glycol (PEG) and the luminescent properties of europium. There was no thermal decomposition of the complex of Eu-PEG until $300^{\circ}C$. SEM showed that the complex of Eu-PEG can be dispersed in PE.

• Journal of the Korean Chemical Society
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• v.60 no.5
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• pp.317-320
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• 2016

Efficient copper removal from water was achieved by using surface modified silica spheres with 3-mercaptopropyltrimethoxysilane (MPTMS) using base catalyst. The surface modification of silica spheres was performed by hydrolysis and condensation reactions of the MPTMS. The characteristic infrared absorption peaks at 2929, 1454, and 1343 cm⁻¹ represent the −CH₂ stretching vibration, asymmetric deformation, and deformation, respectively. The absorption peaks at 2580 and 693 cm⁻¹ corresponding the −SH stretching vibration and the C-S stretching vibration indicate the incorporation of MPTMS to the surface of silica spheres. Field emission scanning electron microscope (FESEM) image of the surface modified silica sphere (SMSS) shows nano-particles of MPTMS on the surface of silica spheres. High concentration of copper solution (1000 ppm) was used to test the copper removal efficiency and uptake capacity. The FESEM image of SMSS treated with the copper solution shows large number of copper lumps on the surface of SMSS. The copper concentration drastically decreased with increasing the amount of SMSS. The residual copper concentrations were analyzed using inductively coupled plasma mass spectrometer. The copper removal efficiency and uptake capacity with 1000 ppm of copper solution were 99.99 % and 125 mg/g, respectively.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2663-2670
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• 2013

The purpose of stability testing is to provide evidence about how the quality of a drug varies with time under the influence of a variety of environmental factors. In this study, erythropoietin (EPO) was analyzed under different pH (pH 3 and pH 9) and temperature ($25^{\circ}C$ and $40^{\circ}C$) conditions according to current Good Manufacturing Practice (cGMP) and International Conference on Harmonisation (ICH) guidelines. The molecular weight difference between intact EPO and deglycosylated EPO was determined by SDS-PAGE, and aggregated forms of EPO under thermal stress and high-pH conditions were investigated by size exclusion chromatography. High pH and high temperature induced increases in dimer and high molecular weight aggregate forms of EPO. UPLC-ESI-TOF-MS was applied to analyze the changed modification sites on EPO. Further, normal-phase high-performance liquid chromatography was performed to identify proposed glycan structures and high pH anion exchange chromatography was carried out to investigate any change in carbohydrate composition. The results demonstrated that there were no changes in modification sites or the glycan structure under severe conditions; however, the number of dimers and aggregates increased at $40^{\circ}C$ and pH 9, respectively.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1143-1145
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• 2011

The synthesis of novel iminecalix[4]arenes and further modification thereafter is described using a synthetic strategy. The reaction of the benzaldehyde derivatives with tetraamine functions on the calix[4]arene easily afforded the pure compounds in 92.4-95.7% yields, regardless of the effect of the substituents on the benzaldehyde derivatives. These compounds were stable under the conditions to obtain their analogue dialkylated in the narrow rim, with 83.2-89.9% yields. Characterization of the newly synthesized iminecalix[4]arene derivatives by spectroscopic methods revealed that all compounds are in the cone conformations.

• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.41-48
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• 1994

The xylanase from alkali-tolerant Bacillus sp. YA-14 was purified to homogeneity by CM-cellulose, Sephadex G-50, and hydroxyapatite column chromatographies. The molecular weight of the purified enzyme was estimated to be 20, 000 Da by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme slightly hydrolyzed carboxymethyl cellulose and Avicel, but did not hydrolyze soluble starch, dextran, pullulan, and ${\rho}-nitrophenyl-{\beta}$-D-xylopyranoside. The maximum degree of hydrolysis by enzyme for birchwood xylan and oat spelts xylan were 47 and 40%, respectively. The Michaelis constants for birchwood xylan and oat spelts xylan were calculated to be 3.03 mg/ml and 5.0 mg/ml, respectively. The activity of the xylanase was inhibited reversibly by $HgCl_2$, and showed competitive inhibition by N-bromosuccinimide, which probably indicates the involvement of tryptophan residue in the active center of the enzyme. The Xylanase was identified to be xylose-producing endo-type xylanase and did not show the enzymatic activities which cleave the branch point of the xylan structure.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2459-2465
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• 2007

V2O5/TiO2-ZrO2 catalyst modified with V2O5 was prepared by adding Ti(OH)4-Zr(OH)4 powder into an aqueous solution of ammonium metavanadate followed by drying and calcining at high temperatures. The characterization of prepared catalysts was performed using XRD, DSC, solid-state 51V NMR, and FTIR. In the case of calcination temperature of 500 oC, for the catalysts containing low loading V2O5 below 25 wt % vanadium oxide was in a highly dispersed state, while for catalysts containing high loading V2O5 equal to or above 25 wt % vanadium oxide was well crystallized due to the V2O5 loading exceeding the formation of monolayer on the surface of TiO2-ZrO2. The strong acid sites were formed through the bonding between dispersed V2O5 and TiO2-ZrO2. The larger the dispersed V2O5 amount, the higher both the acidity and catalytic activities for acid catalysis.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.61-65
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• 2010

Ultrathin atomic layer deposition (ALD) coatings were found to enhance the performance of lithium-ion batteries (LIBs). Previous studies have demonstrated that $LiCoO_2$ cathode powders coated with metal oxides with thicknesses of $\sim100-1000{\AA}$ grown using wet chemical techniques improved LIB performance. In this study, $LiCoO_2$ powders were coated with conformal $Al_2O_3$ ALD films with thicknesses of only $\sim3-4{\AA}$ established using 2 ALD cycles. The coated $LiCoO_2$ powders exhibited a capacity retention of 89% after 120 charge-discharge cycles in the 3.3~4.5 V (vs. $Li/Li^+$) range. In contrast, the bare $LiCoO_2$ powders displayed only a 45% capacity retention. This dramatic improvement may result from the ultrathin $Al_2O_3$ ALD film acting to minimize Co dissolution or to reduce surface electrolyte reactions.

• BMB Reports
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• v.28 no.1
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• pp.40-45
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• 1995

Acetolactate synthase purified from Serratia marcescens ATCC 25419 was rapidly inactivated by the thiol specific reagent p-chloromercuribenzoate (PCMB), the tryptophan specific reagent N-bromosuccinimide (NBS), and the arginine modifying reagent phenylglyoxal (PGO). Inactivation by PCMB was prevented by both ${\alpha}$-ketobutyrate and pyruvate, and the second order rate constant for the inactivation was $2480\;M^{-1}{\cdot}min^{-1}$. The reaction order with respect to PCMB was 0.94. The inactivation of the enzyme by NBS was also substantially reduced by both ${\alpha}$-ketobutyrate and pyruvate. The second order rate constant for inactivation by NBS was $15,000\;M^{-1}{\cdot}min^{-1}$, and the reaction order was 2.0. On the other hand, inactivation by PGO was partially prevented by ${\alpha}$-ketobutyrate, but not by pyruvate. The second order rate constant for the inactivation was $1480\;M^{-1}{\cdot}min^{-1}$ and the order of reaction with respect to PGO was 0.75. These results suggest that essential cysteine, tryptophan and arginine are located at or near the substrate binding site.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.569-574
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• 2005

In this study, alginic acid that had an high affinity for a heavy metal and was noted for biological adsorbent was modified by an oxidizer, $KMnO_4$. Chemical modification changed hydroxyl of the alginic acid into carboxyl and compare with alginic acid, modified alginic acid exhibited a characteristics that carboxyl groups are comparatively high. For the use of them as an adsorbent, beads were prepared by dropping alginic acid and modified alginic acid solution in dilute 2 wt% $CaCl_2$ solution for non water soluble. The amount of removed $Cu^{2+}$ and $Pb^{2+}$ by modified alginic acid beads showed 84.7 mg and 90.9 mg per gram of beads, respectively. And it showed the amount of adsorbed heavy metal ions 10~20% higher than that of alginic acid beads in range of pH 4~7. In particular, modified alginic acid have a good adsorption capacity for $Cu^{2+}$ and $Pb^{2+}$ by Freundlich adsorption isotherm. According to this study, it is verified that alginic acid that is a nature high molecular substance improved capacity for actual application by increased heavy metal adsorption capacity by chemical modification.