• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.893-895
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• 2009

In this paper, we described the unique and novel method to prepare two kinds of electro-active particles, black and white particles with different polarity. The surface of the particles was characterized to be uniform and clean by adopting spray dryer as a tool for genesis of particles; neither surfactants nor high dielectric medium like water was employed during particle preparation step. The other purpose of this study is to investigate the factors that contribute high driving voltage of particlebased display like QR-LPD. We extracted parameters interaction between particle and electrode, and between oppositely charged particles. Here we reported an excellent behavior of particle-based display that showed low operating voltage, high contrast ratio as high as 8:1 without scarification of quick response time. By optimizing the particle size, charge per mass, selection of external additive sets, a lower driving voltage as low as 40V for the particles with $10{\mu}m$ volume average diameter was obtained.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.3057-3060
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• 2009

Ionic palladium(II) complex, [($Me_4en)Pd(L)]_2(ClO_4)_4\;(Me_4$en = N,N,N',N'-tetramethylethylenediamine; L = bis-(4-(4-pyridylcarboxyl)phenyl)methane), allows to form a monodisperse submicrosphere without any template or additive. Surface-perchlorates on the submicrosphere have been exchanged by anionic pH indicators such as thymol blue, bromothymol blue, and bromocresol green. The ionic and amphiphilic properties of the palladium(II) complex appear to be primarily associated with the formation and easy surface-anion exchange of submicrosphere. The surface-anion exchange through the electrostatic interaction is a very good tool for the surface-modification. The color of the pH indicator-exchanged submicrospheres is very sensitive to pH and Hg$^{2+}$ cation, and thus they are promising to submicrospherical indicators.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06b
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• pp.129-153
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• 1996

In aqueous slurry processing of silicon nitride, the interaction of dispersant and binder on the surface of particles was studied to identify the effect of these additives on ceramic powder processing. Polymethacrylic acid (PMAA) and polyvinyl alcohol (PVA) were used as dispersant and binder, respectively. the adsorption isotherms of PMAA and PVA for the silicon nitride suspension were determined, while the adsorption of PMAA was differentiated in the mixed additive system by ultraviolet spectroscopy. These experiments were done in order to investigate the effect of these organic additives on the physicochemical properties of silicon nitride suspensions. The electrokinetic behavior of silicon nitride was subsequently measured by electrokinetic sonic amplitude (ESA). As PMAA adsorbed onto silicon nitride, the isoelectric point (pHicp) shifted from pH=6.7 to acidic pH, depending on the surface coverage of PMAA. However, adsorption of PVA did not change the pHicp of suspensions, but did decrease the surface potential of silicon nitride moderately. The rheological behavior of silicon nitride suspensions was measured to assess the stability of particles in aqueous media, and was correlated with the electrokinetic behavior and adsorption isotherm data for silicon nitride.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.241-245
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• 2005

Laccase catalyzes the oxidation and polymerization of aromatic compounds in the presence of molecular oxygen. Studies were conducted to characterize the use of polyethylene glycol (PEG) as an additive to keep up the enzymatic stability. The enzymatic activities highly remained and bisphenol A (BPA) was rapidly converted in the presence of 5 mg/l of PEC. These effects were accomplished with PEG of molecular weight 3,350. A linear relationship was found between the quantity of BPA to be converted $(10-120\;{\mu}M)$ and the optimum dose of PEC required for greater than $95\%$ conversion. This result suggests that it is the interaction between the PEG and the reaction products. In the optimum dose of PEG, the aeration of reaction mixture neither enhanced the conversion of BPA nor retarded the inactivation of the enzyme.

• Korean Journal of Pharmacognosy
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• v.31 no.4
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• pp.407-411
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• 2000

Antibacterial activities of magnolol (MGL) and honokiol (HKL) in combination with four representative antibiotics-amoxicillin (AMPC), oxytetracyclin (OTC), gentamicin (GM) and chloramphenicol (CAP)-were evaluated against four bacterial strains. When tested by disk-plate method, five out of eight combinations such as HKL-AMPC, HKL-CAP, MGL- AMPC, MGL-OTC, and MGL-CAP showed additive to synergistic interaction against gram- negative bacterium Salmonella typhimureum. Of these, MGL-AMPC combination turned out to be antagonistic against Sarcina lutea and Bacillus thurungiensis. Against these two grain-positive bacteria, only HKL-GM combination showed additivity to synergism. All the other combinations showed no interactions. Despite these results, however, no synergism was observed in checkerboard titration assay.

• Bulletin of the Korean Chemical Society
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• v.3 no.1
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• pp.1-4
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• 1982

A quantitative treatment of ${\pi}$-nonbonded and $n-{\sigma}^{\ast}$ interactions and through-bond coupling effect was attempted using n-butane, n-butyl radical, and tetramethylene diradical. Results of STO-3G level calculations showed that: (1) conformational preferences can be predicted quantitatively based solely on the additive effect of ${\pi}$-nonbonded and $n-{\sigma}^{\ast}$ interactions, the predominant effect being the ${\pi}$-nonbonded interactions, (2) $(n-{\sigma}^{\ast})_{anti}$ is destabilizing whereas $(n-{\sigma}^{\ast})_{syn}$ is weakly stabilizing, which are contrary to what we expect from the normal $n-{\sigma}^{\ast}$ interaction, (3) througb-bond coupling of the two radical lobes is destabilizing for the triplet but stabilizing for the singlet tetramethylene diradical.

• Bulletin of the Korean Chemical Society
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• v.13 no.3
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• pp.280-285
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• 1992

Enantiomeric separation of free amino acids has been achieved by a reversed phase liquid chromatography with addition of a Cu(Ⅱ) complex of N-alkyl-L-proline (alkyl: propyl, pentyl or octyl) to the mobile phase. The amino acids eluted were detected by a postcolumn OPA system. N-alkyl-L-proline was prepared and used as a chiral ligand of Cu(Ⅱ) chelate for the enantiomeric separation. The concentration of the Cu(Ⅱ) chelate, the organic modifier and pH affect the enantiomeric separation of free amino acids. The retention behaviour, varied with change in pH and the concentration of the Cu(Ⅱ) chelate, was different compared with those of the derivatized amino acids. The elution orders between D- and L-forms were consistent except histidine showing that L-forms elute earlier than D-forms. The retention mechanism for the enantiomeric separation can be illustrated by the stereospecificity of the ligand exchange reaction and the hydrophobic interaction between the substituent of amino acids and reversed phase, $C_18$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.255-256
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• 2022

We synthesized catechol-conjugated chitosan (CCC) to study its usefulness as a construction material additive in cement mortar. The degree of catechol conju-gation (DOC_cat) of the synthesized CCC was determined to be approximately14% by UV-vis and ¹H NMR spectroscopy. Furthermore, the hydroxyl and amine groups in CCC could play a crucial role in hydrogen bonding, metal coordination, and cross-linking processes via interaction with adducts from cement mortar. In this study, we observedanimprovement in the compressive strength and absorption rate, suggesting that CCC is a promising candidateforhigh-performance cement mortar.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.8
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• pp.4063-4070
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• 2016

Background: Cytochrome P450 2E1 (CYP2E1) and catechol-O-methyltransferase (COMT) genes may contribute to susceptibility to lung cancer because of their critical involvement in mechanisms of carcinogenesis. Materials and Methods: We evaluated the role of CYP2E1 rs2031920 and COMT rs4680 in a case-control study involving 462 lung cancer cases and 379 controls in Japanese. Logistic regression was used to assess adjusted odds ratios (OR) and 95% confidence intervals (CI). Multiplicative and additive interactions with cigarette smoking or alcohol use were also examined. Results: Neither CYP2E1 rs2031920 nor COMT rs4680 was associated with lung cancer risk overall. However, smokers with the CC genotype of CYP2E1 rs2031920 (OR = 3.57, 95% CI = 2.26 - 5.63) presented a higher risk of lung cancer than those with at least one T allele (OR = 2.91, 95% CI = 1.70 - 4.98) as compared to never-smokers with at least one T allele (reference). Subjects with excessive drinking and the CC genotype of CYP2E1 rs2031920 had a significantly higher risk (OR = 2.22, 95% CI =1.39 - 3.56) than appropriate drinkers with at least one T allele. A similar tendency was observed between COMT rs4680 and either smoking or drinking habits. There were no multiplicative or additive interactions between the polymorphisms and either smoking or alcohol use. Conclusions: Our findings indicate that CYP2E1 rs2031920 and COMT rs4680 are not major contributors to lung cancer risk in our Japanese population. Future studies on the genetics of lung cancer in Japanese and their environment interactions are required.

• The Journal of Korean Medicine
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• v.19 no.2
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• pp.228-243
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• 1998

This study was undertaken to evaluate the effect of Sunghyangchungisan (SHCS) on the regulation of vascular tone. Vascular rings isolated from rabbit carotid artery were myographed isometrically in isolated organ baths and the effect of SHCS on contractile activities were determined. SHCS relaxed the arterial rings which were pre-contracted by phenylephrine(PE). The responses to SHCS were partially dose-dependent at concentrations lower than 0.5 mg/ml. When SHCS was applied prior to the exposure to PE, it inhibited the PE-induced contraction by a similar magnitude which was comparable to the relaxation of pre-contracted arterial rings. Washout of SHCS after observing its relaxant effect resulted in a full recovery of PE-induced contractions, indicating that the action mechanism is reversible. The observation that SHCS did not change the $ED_{50}$ of PE on its dose-response curve ruled out the possible interaction of SHCS and ${\alpha}-receptor$. The relaxant effect of SHCS was not affected by removal of endothelium, and pretreatment of the arterial rings with methylene blue or nitro-L-arginine. This results suggest that the action of SHCS is not mediated by endothelium nor soluble guanylate cyclase. SHCS relaxed high $K^{+}-induced$ contractions as well, whereas it failed to relax phorbol ester-induced contractions. When contraction was induced by additive application of $Ca^{2+}$ in arterial rings which were pre-depolarized by high $K^+$ in a $Ca^{2+}-free$ solution, the relaxant effect of SHCS was attenuated by increasing the $Ca^{2+}$ concentration. SHCS, when applied to the arterial rings pre-contracted by PE and then relaxed by nifedipine, a $Ca^{2+}$ channel blocker, did not show additive relaxation. From above results, it is suggested that SHCS relax PE-induced contraction of rabbit carotid artery in an endothelium-independent manner, and inhibition of $Ca^{2+}$ influx may contribute to the underling mechanism.