• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.438-442
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• 2006

The degradation of Nafion membrane by hydrogen peroxide was investigated in polymer electrolyte membrane fuel cell (PEMFC). Degradation tests were carried out in a solution of $10{\sim}30%$ hydrogen peroxide containing 4ppm $Fe^{2+}$ ion which is well known as Fenton's reagent at $80^{\circ}C$ for 48hr. Characterization of degraded membranes were examined through the IR, Water-uptake, Ion exchange capacity, mechanical strength and $H_2$ permeability. After degradation, C-F, S-O and C-O chemical bonds of membrane were broken by radical formed by $H_2O_2$ decomposition. Breaking of C-F bond which is the membrane backbone reduced the mechanical strength of Nafion membrane and hence induced pinholes, resulting in increase of $H_2$ crossover through the membrane. Also the decomposition of C-O and S-O, side chain and terminal bond of membrane, decreased the ion exchange capacity of the membrane.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2454-2458
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• 2007

Exploring the basic concepts for the design of CO2-philic molecules is important due to the possibility for “green” chemistry in supercritical CO2 as substitute solvent systems. The Lewis acid-base interactions and C?H…O weak hydrogen bonding were suggested as two key factors for the solubility of CO2-philic molecules. We have performed high level quantum mechanical calculations for the van der Waals complexes of CO2 with trimethylphosphate and trimethylphosphine oxide, which have long been used for metal extractants in supercritical CO2 fluid. Structures and energies were calculated using the MP2/6-31+G(d) and recently developed multilevel methods. These studies indicate that the Lewis acid-base interactions have larger impact on the stability of structure than the C?H…O weak hydrogen bonding. The weak hydrogen bonds in trimethylphosphine oxide have an important role to the large supercritical CO2 solubility when a metal is bound to the oxygen atom of the P=O group. Trimethylphosphate has many Lewis acid-base interaction sites so that it can be dissolved into supercritical CO2 easily even when it has metal ion on the oxygen atom of the P=O group, which is indispensable for a good extractant.

• Korean Journal of Crystallography
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• v.16 no.1
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• pp.6-10
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• 2005

A novel potential linking ligand (4-nitro-benzylidene)-(3-nitro-phenyl)-amine (1) was prepared from 4-nitrobenzaldehyde and 3-nitroaniline by the Schiff-base condensation. From the reaction between 1 and dichlorobis(benzonitrile)palladium (II) $(PdCl_2(NCPh)_2)$, an unexpected product $trans-PdCl_2(NO_2-C_6H_4-NH_2)_2$ (2) was isolated. Compounds 1 and 2 were structurally characterized by X-ray diffraction. In compound 2, the $NH_2$ hydrogen atoms in the 3-nitroaniline ligand participate in intermolecular N-H${\cdot}\;{\cdot}\;{\cdot}\;$Cl hydrogen bonds.

• Journal of Environmental Science International
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• v.5 no.5
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• pp.579-583
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• 1996

This study is involved to develop new catalysts to decompose plastics, detergents and surfactants containing synthetic peptide bonds. As the first year research, the catalytic-hydrolysis of amide bond in copper complex was accomplished. The hydrolysis reaction in aqueous solution was monitored by UV/VIS spectroscopy. As the pH of the solution Is increased and the temperature is raised, the reaction rate increases. The reaction rate is observed as the first order kinetic behavior for the copper complex. The metal catalyzed hydrolysis mechanism is proposed cia metal-hydroxide in the pH region of 5.5 to 6.3. The results of characterization of the catalytic reaction mechanism can be applied to develop new catalysts for peptide bond degradation in further research.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.5
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• pp.38-45
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• 1989

We have studied the electrical characteristics of the hydrogenated amorphous silicon (a-Si:H) ambiploar thin film transistors (TET'S)using 100ppm boron-doped a-Si:H as an active layer. The enhancement of drain current due to the double injection behavior has been observed in the p-channel operation of the TFT. The drain current decreases with time in streched exponential form when the gate voltage is positive. The result indicates that the dangling bonds created by electron accumulation show identical time dependence as the diffusion of hydrogen in the film. We observed the experimental evidence that the doping efficiency changes either when the gate bias is applied or when the light is illuminated on boron-doped a-Si:H.

• Journal of the Korean Chemical Society
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• v.7 no.4
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• pp.293-298
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• 1963

The crystal structure of ethylenediamine dihydrochloride has been determined by the two-dimensional Patterson methods and refined by two-dimensional Fourier syntheses. The unit cell dimensions are a = 4.44${\pm}$0.02, b = 6.88${\pm}$0.02, c = 9.97${\pm}$0.02 ${\AA}$, ${\beta}$ = 92${\pm}$$1^{\circ}$. The space group is $P2_1_{/c}$. The carbon and nitrogen atoms in the ethylenediamine itself lie on one plane and its structure has a trans-form with a centre of symmetry in it, and C-C distance of 1.54 ${\AA}$, C-N distance of 1.48${\AA}$ and C-C-N bond angle of $109.07^{\circ}$. The molecules are linked by N-H${\cdots}$Cl hydrogen bonds with distance of 3.14, 3.16 and 3.22 ${\AA}$ forming three dimensional network. The values of reliability factor for F(okl), F(hol) and F(hko) are 0.11, 0.10 and 0.09 respectively.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1443-1445
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• 1996

Hydrogen passivation enhances the electrical characteristics of poly-Si TFT(Thin Film Transistor). However, the weak Si-H bonds, generated during hydrogenation, degrade the stability of the device. So, we carried out the passivation treatment with $NH_3$ or $N_2$. We compared the effect of $NH_3$ or $N_2$ passivation treatments with that of hydrogenation in terms of stability. Through the $NH_3$ passivation treatment, we obtained the most improved subthreshold swing of 1.2V/decade from the initial subthreshold swing of 1.56V/decade. When electrical stress was given, the $NH_3$ passivated devices showed best electrical stability.

• Archives of Pharmacal Research
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• v.3 no.1
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• pp.37-49
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• 1980

Chlorpropamide, $C_{10}H_{13}N_{2}O_{3}SCI$, forms orthofombic crystals of space group $P_{2}_{ 1}2_{1}2_{1}$ with a 9.066 $\pm$ 0.004, b = 5.218 $\pm$ 0.003, c = 26, 604 $\pm$, 0.008 $\AA$, and four molecules per cell. Three dimensional photographic data were collected with Mo-K$\alpha$ radiation. The structure was determined using Patterson, Fourier and Difference syntheses methods and refined by the block-diagonal least-squares methods with anisotropic thermal parameters for all nonhydrogen atoms and isotropic thermal parameters for all hydrogen atomes. The final R value was 0.10 for the 1823 observed independent reflections. The dihedral angle between the planes through the benzene ring and the urea goup is 99$^{\circ}$. The conformational angle formed by the projection of the S-C(1) with that of N(1)-C(7) when the projection is taken along the S-N(1) bond is 76$^{\circ}$. The molecule appears to form with neighbouring molecules two hydrogen bonds, N(1)..H...O(3) and N(2)-H...0(2) of lengths 2.774 and 2.954$\AA$ respectively related by screw diads parallel to the a axis. Adjacent molecules parallel to b and c axis are bound together by van der Wasls forces.

• Textile Coloration and Finishing
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• v.7 no.4
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• pp.8-15
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• 1995

A series of thermotropic Polyurethanes mesogenic unit were synthesized by polyaddition of a para-type diisocyanate such as 2,5-tolylene diisocyanate(2,5-TDI) with 4-4'-bis($\omega$-hydroxyalkoxy) biphenls(BPm: $HOCmH_{2m}OC_{6}H_{4}OC_{m}H_{2m}OH$ : m is the carbon number of the hydroxyalkoxy group) in DMF. Intrinsic viscosities of the polymers were in the range of 0.41~0.99dL/g DSC thermograms for these polymers exhibited two endothermic peaks corresponding to phase transitions of melting and isotropization. For examplem polyurethane 2,5-TDI/BPll with [η]=0.99 prepared from 2.5-TDI and 4,4'-bis[11-hydroxyundecaoxy biphenyl(BP11) a liquid crystalline phase from 156 to 173$^{\circ}C$. The thermotropic properites of liquid crystalline polyurethanes have been investigated by wide-angle X-ray scatter(WAXS), infrared (IR) spectroscopy, and differential scanning calorimetry (DSC). The mesomorphic behavior of the polyurethanes was concluded to be greatly dependent on the intermolecular hydrogen bonds through the urethane.

• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.621-625
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• 1993

Kinetic studies are conducted for the reactions of Y-benzoyl, Y-benzenesulfonyl and Y-benzyl halides with X-anilines in acetonitrile, and the transition state (TS) structures and their variations with substituents X and Y are discussed. The magnitude of the cross-interaction constants, $\rho$xy, is the largest and the inverse secondary kinetic isotope effect (SKIE), $k_H/k_D$ < 1.0, with deuterated aniline nucleophiles is the smallest for benzoyl fluoride reflecting the tightest TS for this compound. The SKIEs for sulfonyl halides are relatively large due to a relatively large, diffuse nature of the reaction center, S, causing weaker steric hindrance to the vibrations of the two N-H(D) bonds. For benzoyl and sulfonyl halides, the trends in $k_H/k_D$ and $Ir_XI$ variations with $\sigma$Y contradict each other, which is rationalized by the negative charge accumulation on the reaction center, CO and SO$_2$, causing inefficient transfer for the substrate with an electron donating substituent.