• Journal of Environmental Science International
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• v.29 no.8
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• pp.801-808
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• 2020

In this study, an effective fluorescence pH sensor based on conjugated polyelectrolyte micelles (CPMs) was devised for detecting extremely acidic conditions. An amphiphilic coumarin derivative (CC12-N), a building block, was prepared, into which an ionizable amino group, aryl amine, was incorporated as a potential hydrophilic moiety. This monomer displays self-assembled micelle formation in extremely acidic pH ranges, giving a hydrophobic π-extended conjugated system at the inner part and hydrophilic functionality at the periphery, resulting in efficient fluorescence intensity enhancement. This new micelle-based fluorescence provides an efficient sensing platform for detecting very low pH values in the presence of competing substances.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.735-743
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• 1993

The electrocatalytic reduction of oxygen is investigated by cyclic voltammetry and chronoamperometry at glassy carbon electrode and carbon microelectrode coated with a variety of cobalt phenylprophyrins in various pH solutions. Oxygen reduction catalyzed by the monomeric porphyrin Co(Ⅱ)-TPP mainly occurs through the 2e$^-$ reduction pathway resulting in the formation of hydrogen peroxide whereas electrocatalytic process carried out 4e$^-$ reduction pathway of oxygen to H$_2$O at the electrodes coated with cofacial bis-cobalt phenylporphyrins in acidic solution. The electrocatalytic reduction of oxygen is irreversible and diffusion controlled. The reduction potentials of oxygen in various pH solutions have a straight line from pH 4 to pH 13, but level off in strong acidic solution. The reduction potentials of oxygen shift to positive potential more 400 mV at the electrode coated with monomer Co-TPP compound than bare glassy carbon electrode while 750 mV at the electrode coated with dimer Co-TPP compound.

• Journal of the Korean Applied Science and Technology
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• v.11 no.2
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• pp.75-87
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• 1994

The metal complexes containing amino acidic ligands were prepared by using 11 kinds of amino acids as ligands and Ni, Cu, Co, Zn, Fe as a central metal. The starting was continued for 4hrs at room temperature. But Bis(D,L-Serine)Ni (II), and (D,L-Serine)Co (II) were prepared by heating method($80^{\circ}C$). In order to investigated reaction activity of Bis(D,L-Aspartato) Metal(II), stirring time was varied and Bis(D,L-Tyrosine ) Metal(II) used different divalent metal salts. We anticipate getting a great value from these prepared complexes as a monomer and a catalyst of polymerization which has peculier characteristics.

• Bulletin of the Korean Chemical Society
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• v.9 no.4
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• pp.248-251
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• 1988

Mechanism of electrochemical polymerization of pyrrole (Py) on a Pt electrode in acidic aqueous solutions was studied by means of potentiostatic measurements, cyclic voltammetry and chronopotentiometry. Pyrrole molecule appeared to be initially oxidized via two-electron transfer step to produce oxidized pyrrole ion ($Py^+$), which was coupled with a non-oxidized pyrrole to yield a dimerized species, Py-Py. The Py-Py thus formed was further oxidized again via two-electron transfer step, which was followed by coupling with non-oxidized monomer and by concomitant expulsion of a $H^+$. Then the latter chain extension process was repeated. The chain extension and polypyrrole oxidation reactions occurred competitively.

• Journal of dental hygiene science
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• v.23 no.4
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• pp.264-270
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• 2023

Background: Resin-based dental materials release residual monomers or other substances from incomplete polymerization into the oral cavity, thereby causing adverse biological effects on oral tissue. 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP), an acidic monomer containing dihydrogen phosphate and methacrylate groups, is the most commonly used component of resin-based dental materials, such as restorative composite resins, dentin adhesives, and resin cements. Although previous studies have reported the cytotoxicity and biocompatibility in various cultured cells, the effects of resin monomers on cellular aging have not been reported to date. Therefore, this study aimed to investigate the effects of the resin monomer 10-MDP on cellular senescence and inflamm-aging in vitro. Methods: After stimulation with 10-MDP, MC3T3-E1 osteoblast-like cells were examined for cell viability by WST-8 assay and reactive oxygen species (ROS) production by flow cytometry. The protein and mRNA levels of molecular markers of aging were determined by western blotting and RT-PCR analysis, respectively. Results: Treatment with 0.05 to 1 mM 10-MDP for 24 hours reduced the survival of MC3T3-E1 cells in a concentration-dependent manner. The intracellular ROS levels in the 10-MDP-treated experimental group were significantly higher than those in the control group. 10-MDP at a concentration of 0.1 mM increased p53, p16, and p21 protein levels. Additionally, an aging pattern was observed with blue staining due to intracellular senescence-associated beta-galactosidase activity. Treatment with 10-MDP increased the levels of tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and IL-8, however their expression was decreased by mitogen-activated-protein-kinase (MAPK) inhibitors. Conclusion: Taken together, these results suggest that the exposure of osteoblast-like cells to the dental resin monomer 10-MDP, increases the level of cellular senescence and the inflammatory response is mediated by the MAPK pathway.

• Journal of the Korean Chemical Society
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• v.38 no.12
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• pp.885-890
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• 1994

Kinetics of electrochemical polymerization of aniline on a tungsten electrode in acidic aqueous solution was studied by means of cyclic voltammetry and kinetic measurements of anodic oxidation. Aniline molecule appeared to be intially oxidized via two-electron transfer to produce oxidized deprotonated aniline ion, which subsequently undergoes nucleophilic attack to the parent aniline and results in head to tail coupling to yield a dimerized species. But, being contrary to the case of Pt electrode, the propagation of polymerization occured through attack of the monomer by the oxidized aniline monomer to polymer. The growth rate of polyaniline was slow in comparison with the growth on Pt electrode. The degradation products were confirmed to be not p-benzoquinone(BQ) but p-phenylenediamine(p-PDA) by spectrophotometry, which agrees with the fact that oxidation of p-PDA was not observed below 1.0 V.

• Textile Coloration and Finishing
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• v.20 no.2
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• pp.38-46
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• 2008

PET fabrics were cationized via photografting under continuous UV irradiation with a cationic monomer. The grafted PET was dyed with three acid dyes. Effect of dye concentration, dyeing time, temperature and pH on acidic dyeing of the cationized PET fabrics was assessed to find optimal dyeing condition. The cationized fabrics was successfully dyed at $75^{\circ}C$ under pH 5.5. However the dyeing sites of the grafted fabrics were nearly occupied above 5%owf dye concentration and the rapid exhaustion of the anionic dyes was observed. The dyeability of the cationized PET fabrics was increased proportionally with increasing percent grafting because of the introduction of ionic attraction between quaternary ammonium groups and acid dyes. Lower dyeability both at alkaline and pH 3 condition attributed to negative zeta potentials of the grafted fabrics and the reduced charge of the acid dyes respectively.

• Bulletin of the Korean Chemical Society
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• v.20 no.11
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• pp.1303-1308
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• 1999

Conducting poly(3,4-ethylenedioxythiophene) (PEDT) films with metalloporphyrins incorporated as the counter ions were prepared by electropolymerization of the monomer in the presence of metal-tetra(sulfonatophenyl) porphyrin anions. Cathodic reduction of oxygen on the resulting conducting polymer films was studied. The overpotential for O2 reduction on electrodes with cobalt-porphyrin complex was significantly smaller in acidic solutions than on gold. In basic solutions, the overpotential at low current densities was close to those on platinum and gold. Polymer electrode with Co-complex yielded higher limiting currents than with Fe-complex, although the Co-complex polymer electrode was a poorer electrocatalyst for O2 reduction in the activation range of potential than the Fe counterpart. From the rotating ring-disk electrode experiments, oxygen reduction was shown to proceed through either a 4-electron pathway or a 2-electron pathway. In contrast to the polypyr-role-based electrodes, the PEDT-based metalloporphyrin electrodes were stable with wider potential windows, including the oxygen reduction potential. Their electrocatalytic properties were maintained at temperatures up to 80℃ in KOH solutions.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.338-344
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• 1998

New type of chitosan derivatives, chitosan-g-MAP, were synthesized by graft copolymerization of mono (2-methacryloyl oxyethyl) acid phosphate (MAP) into chitosan, in order to solubilize chitosan in water. Ceric ammonium nitrate was used as an initiator for graft copolymerization. The optimal conditions for graft copolymerization were determined on the basis of reaction temperature, time, and the concentration of initiator and monomer. The reaction conditions for the highest percentage of grafting were as follows: an initiator concentration, 3.5${\times}$10$\^$-3/ M; monomer concentration, 0.19 M; and reaction temperature, 40$^{\circ}C$ The reaction rate reached the maximum value after 4 hrs of reaction. Antifungal activity was tested against Candida albicans, Trichophyton rubrum and Trichophyton violaceum by using chitosan-g-MAP and two other chitosan samples which have degree of deacetylation of 70% (DA-7) and 90% (DA-90). Their antifungal activities were investigated in weak acidic range. Maximum antifungal activity of them was observed at pH 5.75. Chitosan-g-MAP inhibited thoroughly the growth of Candida albicans and Trichophyton violaceum. Howerver, DA-70 and DA-90 showed higher antifungal activities on Trichophyton rubrum than that of chitosan-g-MAP.

• Polymer(Korea)
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• v.32 no.4
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• pp.295-304
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• 2008

This study examined the oxidative polycondensation reaction of 2-[(pyridin-4-yl-) methyleneamino] pyridine-3-ol (2-PMAP) using air $O_2$ and NaOCl oxidants at various temperatures and times in aqueous alkaline and acidic media. Under these reactions, the optimum reaction conditions using air $O_2$ and NaOCl oxidants were determined for 2-PMAP. The number-average molecular weight ($M_n$), weight average molecular weight ($M_w$), and polydispersity index (PDI) values of O-2-PMAP synthesized in aqueous alkaline media were found to be 960, 1230, and $1.281\;g\;mol^{-1}$ using NaOCl, and 1030, 1520, and $1.476\;g\;mol^{-1}$ using air $O_2$, respectively. At the optimum reaction conditions, the yield of O-2-PMAP in aqueous alkaline media was 92.50% and 85.70% for air $O_2$ and NaOCl oxidants, respectively. The yield of O-2-PMAP in aqueous acidic media was 88.5% and 88.0% for NaOCl and air $O_2$ oxidants, respectively. O-2-PMAP was characterized by $^1H-$, $^{13}C$-NMR, FT-IR, UV-vis, SEC, and elemental analysis. TGA-DTA analysis revealed O-2-PMAP and its oligomer metal complex compounds, such as $Co^{+2}$, $Ni^{+2}$, and $Cu^{+2}$, to be stable against thermal decomposition and their weight losses at $1000^{\circ}C$ were found to be 73.0, 58.0, 53.5%, and 50.0%, respectively. In addition, the antimicrobial activities of the monomer and oligomer were tested against E. Coli (ATCC 25922), E. Faecelis (ATCC 29212), P. Auroginasa (ATCC 27853), and S. Aureus (ATCC 25923).