• Journal of the Korean Chemical Society
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• v.28 no.4
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• pp.210-216
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• 1984

Solvatochromic comparison methods were applied to determine Taft's solvent parameters, ${\pi}^{\ast}$(solvent polarity-polarizability), ${\alpha}$(solvent hydrogen bond donor acidity) and ${\beta}$ (solvent hydrogen bond acceptor basicity) for MeOH-MeCN solvent mixtures. Swain's solvent parameters A(anion solvation scale) and B(cation solvation scale) were also determined by least square fitting of kinetic data in the same binary solvent mixtures. It was found that: (i)${\beta}$ depends on the basicity of the solvent and increases with the MeOH content owing to the increase in polymeric structure of methanol; (ii) ${\pi}^{\ast}$depends on the dipole moment of the solvent and increases with the MeCN content of the solvent; (iii) ${\alpha}$ increases rapidly with the MeOH content as the hydrogen bond donor acidity of the solvent mixtures increases. Taft's reaction constants a and s and Swain's reaction constants a and b were determined for the reactions reported from our laboratory previously using solvent parameters determined in this work. No meaningful inter-relationship was found between the two set of reaction parameters, but a good linear correlation was found between the ratios a/s and a/b. Solvent effect on the reaction mechanism, substituent effect and leaving group ability were examined in the light of these reaction constants ratios.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.4
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• pp.271-276
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• 2009

The 3-dimensional quantitative structure-activity relationships (3D-QSARs) models between the substituents with changing groups ($R_1$ & $R_2$) of 4-($R_1$)-benzyl alcohol and 4-($R_2$)-phenol derivatives as substrate molecule and their inhibitory activities against tyrosinase were derived and discussed quantitatively. The optimized CoMSIA 2 model have best predictability and fitness ($r^2\;=\;0.858$ & $q^2\;=\;0.951$). The contour maps of optimized CoMSIA 2 model showed that, the inhibitory activities of the analogues against tyrosinase were expected to increase when hydrophobic favor, negative charge favor, steric disfavor and hydrogen bond donor disfavor groups were substituted at the $R^2$ position. When the positive charge and the hydrogen bond donor favor groups were substituted at the $R_1$ position, it is predicted that the substituents will be able to increase the inhibitory activity. However, hydrogen bond acceptor did not affect inhibitory activities of tyrosinase.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2086-2092
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• 2013

Two new high-nitrogen energetic compounds $ZTO{\cdot}2H_2O$ and $ZTO(phen){\cdot}H_2O$ have been synthesized (where ZTO = 4,4-azo-1,2,4-triazol-5-one and phen = 1,10-phenanthroline). The crystal structure, elemental analysis and IR spectroscopy are presented. Compound 1 $ZTO{\cdot}2H_2O$ crystallizes in the orthorhombic crystal system with space group Pnna and compound 2 $ZTO(phen){\cdot}H_2O$ in the triclinic crystal system with space group P-1. In $ZTO(phen){\cdot}H_2O$, there is intermolecular hydrogen bonds between the -NH group of ZTO molecule (as donor) and N atom of phen molecule (as acceptor). Thermal decomposition process is studied by applying the differential scanning calorimetry (DSC) and thermo thermogravimetric differential analysis (TG-DTG). The DSC curve shows that there is one exothermic peak in $ZTO{\cdot}2H_2O$ and $ZTO(phen){\cdot}H_2O$, respectively. The critical temperature of thermal explosion ($T_b$) for $ZTO{\cdot}2H_2O$ and $ZTO(phen){\cdot}H_2O$ is $282.21^{\circ}C$ and $195.94^{\circ}C$, respectively.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.133-140
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• 1986

Extracts of CO-autotrophically grown cells of Acinetobacter sp. 1 were shown to use thionin, methylene blue, or 2,6-dichlorophenol-indophenol, but not NAD, NADP, FAD, or FMN, as electron acceptors for the oxidation of CO under strictly anaerobic conditions. The CO dehydrogenase (CO-DH) in the thes bacterium was found to be an inducible enzyme. The enzyme activity was determined by an assay based on the CO-dependent reduction of thionin. Maximal reaction rates were found at pH 7.5 and $60^{\circ}C$, and the Arrhenius plot revealed an activation energy of 6.1 kcal/mol(25.5kJ/mol). THe $K_m$ m/ for CO was $154{\mu}M$. Known metalchelating agents tested had no effects on the CO-DH activity. No divalent cations tested affect the enzyme activity significantly escept $Cu^{2+}$ which suppressed the activity completely. The enzyme was inhibited by glucose and succinate. The same extracts catalyzed oxidation of hydrogen gas and formate with thionin as electron acceptor. The CO-DH of Acinetobacter sp. 1 was to have no immunological relationship with that of Pseudomonas carboxydohydrogena.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.624-629
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• 2005

The purpose of this study is to investigate the performance of nitrogen removal using autotrophic microorganism in the Membrane-Attached Biofilm Reactor (MABR). The treatment system consists of an aerobic MABR (R1) for nitrification and an anaerobic MABR (R2) for hydrogenotrophic denitrification. Oxygen and hydrogen were supplied through the lumen of hollow-fiber membranes as electron acceptor and donor, respectively. In phase Ι, simultaneous organic carbon removal and nitrification were carried out successfully in R1. In phase II, to develop the biofilm on the hollow-fiber membrane surface and to acclimate the microbial community to autotrophic condition, R1 and R2 were operated independently. The MABRs, R1 and R2 were connected in series continuously in phase III and operated at HRT of 8 hr or 4 hr with $NH_4{^+}-N$ concentration of influent, from 150 to 200 mgN/L. The total nitrogen removal efficiency reached the maximum value of 99% at the volumetric nitrogen loading rate of $1.20kgN/m^3{\cdot}d$ in the combined MABR system with R1 and R2. The results in this study demonstrated that the combined MABR system could operate effectively for the removal of nitrogen in wastewater not containing organic materials and can be used stably as a high rate nitrogen removal technology.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.191-198
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• 2005

Hippuryl-L-histidyl-L-leucine (Hip-L-His-L-Leu, HHL) is the known substrate of ACE, which used often in inhibition kinetic study to design new inhibitor. Here we use HHL molecule as a template to predict pharmacophore which can interact with residues in active site of AnCE, new potential insecticide target protein. To explain physicochemical properties related to molecular geometry and conformational change in reaction field as well as electron density of atoms associated to pharmacophores, geometry optimization, NMR chemical shifts and natural population analysis were performed by ab initio and DFT method. Calculated NMR chemical shifts showed good agreement with the experimental ones and obtained electron densities were used for analyzing pharmacophores of corresponding atoms. Finally, we could extract aye pharmacophores related to hydrophobic aliphatic and aromatic site, hydrogen bonding donor and acceptor site and Zn binding site from the HHL molecule.

• Journal of the Korean Vacuum Society
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• v.16 no.4
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• pp.286-290
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• 2007

We fabricated NiO coated ZnO nanorods using ZnO nanorods grown on a Si substrate. After thermal hydrogenation process of these NiO-ZnO core-shell nanorods, we confirm that Ni nanodots were built up on the surface of ZnO nanorods. Photoluminescence (PL) measurements at T=5 K were made to understand the optical properties of these various nanorods. As samples sequencially transformed into $ZnO{\rightarrow}NiO-ZnO{\rightarrow}Ni$ nanodot-ZnO, PL transition energies and intensities are varied as well. In comparison to pure ZnO nanorod, the acceptor bound exciton ($A^0X$) became the minor peak for NiO-ZnO nanorods. On the other hand, for Ni nanodot-ZnO sample, ($A^0X$) transition peak intensity became the most dominant peak. This is due to the fact that during thermal hydrogenation process, appreciable amounts of Ni and hydrogen ions defused into ZnO nanorod which played as accepters.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3333-3340
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• 2010

A three dimensional pharmacophore model was generated for the molecules which are responsible for anti-inflammatory activities targeting Interleukin-2 inducible tyrosine kinase (Itk). 16 structurally diverse molecules were selected as training set to generate the hypotheses using Discovery Studio v2.1. The best hypothesis, Hypo1, comprises two hydrogen bond acceptor (HBA), one hydrophobic aromatic (HA), one ring aromatic (RA) and shows high cost difference (63.71), high correlation coefficient (0.97) as well as low RMS deviation (0.81). Hypo1 has been further validated toward a test set, decoy set and Fischer's randomization method. Furthermore, Hypo1 was used to screen NCI and Maybridge databases. Finally, 2 hit molecules were identified as potential leads against Itk, which may be useful for future drug development.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3399-3404
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• 2013

A new accepter unit, pyrrolo[3,2-b]pyrrole-2,5-dione, was prepared and utilized for the synthesis of the conjugated polymers containing electron donor-acceptor pair for OPVs. Pyrrolo[3,2-b]pyrrole-2,5-dione unit, regioisomer of the known pyrrolo[3,4-c]pyrrole-1,4-dione, is originated from the structure of stable synthetic pigment. The new conjugated polymers with 1,4-diphenylpyrrolo[3,2-b]pyrrole-2,5-dione, thiophene and carbazole were synthesized using Suzuki polymerization to generate P1 and P2. The solid films of P1 and P2 show absorption bands with maximum peaks at about 377, 554 and 374, 542 nm and the absorption onsets at 670 and 674 nm, corresponding to band gaps of 1.85 and 1.84 eV, respectively. To improve the hole mobility of the polymer with 1,4-bis(4-butylphenyl)-pyrrolo[3,2-b]-pyrrole-2,5-dione unit, which was previously reported by us, the butyl group at the 4-positions of the N-substituted phenyl group was substituted with hydrogen and methyl group. The field-effect hole mobility of P2 is $9.6{\times}10^{-5}cm^2/Vs$. The device with $P2:PC_{71}BM$ (1:2) showed $V_{OC}$ value of 0.84 V, $J_{SC}$ value of 5.10 $mA/cm^2$, and FF of 0.33, giving PCE of 1.42%.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.171-171
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• 2010

GaN 기반 Light emitting diodes(LEDs)의 p-type doping layer는 일반적으로 hole을 발생시키는 acceptor로 Mg이 사용하되고 있다. 보통 Mg이 도핑된 p-type GaN은 >$1\;{\Omega}{\cdot}cm$의 저항이 존재하는데 그 이유는 Mg의 열적 이온화를 위한 activation 에너지가 높아서 상온에서 valence band의 hole concentration는 전체 억셉터 농도의 1%가 되지 않기 ��문이다. 본 논문에서는 높은 hole 농도를 얻기 위해서 metalorganic chemical-vapor deposition (MOCVD)를 장비를 사용하여 사파이어 기판의 misorientation-angle에 따른 p-type a-plane(11-20) GaN 특성을 분석하였다. misorientation-angle은 c축 방향으로 $+0.15^{\circ}$, $-0.15^{\circ}$, $-0.2^{\circ}$, $-0.4^{\circ}$ off된 r-plane(1-102) 사파이어 기판 을 사용하였다. p-type 도핑물질로 bis-magnesium (Cp2Mg) 소스를 사용하였고 성장 과정중 발생하는 hydrogen passivation으로 인한 Mg-H complexes현상을 해결하기위해 conventional furnace annealing (CFA)와 rapid thermal annealing (RTA)를 이용하여 열처리 공정을 진행하였다. 열처리 공정은 Air와 N2 분위기에서 $650^{\circ}C$에서 $900^{\circ}C$ 사이의 다양한 온도에서 수행하였고 Hall 측정을 위해 Ni을 전극 물질로 사용하였다. 상온에서 Accent HL5500IU Hall system을 사용하여 hole concentration, mobility, specific resistance을 측정하였다. 열처리 공정 후 Hall측정 결과 $+0.15^{\circ}$, $-0.15^{\circ}$, $-0.2^{\circ}$, $-0.4^{\circ}$ off된 각 샘플들은 온도, 시간, 분위기에 따라 hole concentration ($7.4{\times}10^{16}cm^{-3}{\sim}6{\times}10^{17}cm^{-3}$), mobility(${\mu}h=\;1.72\;cm^2/V-s\;{\sim}15.2\;cm^2/V-s$), specific resistance(4.971 ohm-cm ~8.924 ohm-cm) 가 변화됨을 확인 할 수 있었다. 또한 광학적 특성을 분석하기 위해 Photoluminescence (PL)을 측정하였다.