• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.704-710
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• 2004

A poly(1-hexyl-3,4-dimethyl-2,5-pyrrolylene) (PHDP) was prepared and its luminescence in tetrahydrofuran (THF) was studied. When PHDP is excited by UV light, it produces very strong blue luminescence. The quantum yield of PHDP (Q = 36.9%) is much greater than that of the monomer, 1-hexyl-3,4-dimethylpyrrole (HDP) with Q = 0.61%. The principal luminescence of PHDP has a single decay component with ca. 1 ns, whereas the decay of HDP is complicated. The molecular structure and conformational behavior of HDP and the oligomers up to trimer have been also determined by ab initio Hartree-Fock (HF/6-31$G^{**}$), density functional theory (DFT-B3LYP/6-31$G^{**}$), and semiempirical (ZINDO) methods. According to the results of calculations, it is proposed that the enhanced quantum yield of the polymer PHDP results mostly from the ${\pi}$-conjugation between neighboring pyrrole rings.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2325-2331
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• 2011

Human CDX1 and CDX2 genes play important roles in the regulation of cell proliferation and differentiation in the intestine. Hox genes clustered on four chromosomal regions (A-D) specify positional signaling along the anterior-posterior body axis, including intestinal development. Using glutathione S-transferase (GST) pulldown assays, molecular interaction measurements, and fluorescence measurements, we found that the homeodomains (HDs) of CDX1 and CDX2 directly interact with that of HOXD8 in vitro. CDX1 showed significant affinity for HOXD8, but CDX2 showed weak affinity for HOXD8. Thus far, three-dimensional structures of CDX1/2 and HOXD8 have not been determined. In this study, we developed a molecular docking model by homology modeling based on the structures of other HD members. Proteins with mutations in the HD of CDX1 (S185A, N190A, T194A, and V212A) also bound to the HD of HOXD8. Our study suggests that the HDs of CDX1/2 resemble those of HOXD8, and we provide the first insight into the interaction between the HDs of CDX1/2 proteins and those of HOXD8.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.564-564
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• 2012

Graphene has been emerged as a fascinating material for future nanoelectronic applications due to its extraordinally electronic properties. However, their zero-bandgap semimetallic nature is a major problem for applications in high performance field-effect transistors (FETs). Graphene nanoribbons (GNRs) with narrow widths (${\geq}10nm$) exhibit semiconducting behavior, which can be used to overcome this problem. In previous reports, GNRs were produced by several approaches, such as electron beam lithography patterning, chemically derived GNRs, longitudinal unzipping of carbon nanotubes, and inorganic nanowire template. Using these methods, however, the width distribution of GNRs was a quiet broad and substantial defects were inevitably occurred. Here, we report a novel approach for fabricating width-tailored GNRs by focused ion beam-assisted chemical vapor deposition (FIB-CVD). Width-tailored phenanthrene ($C_{14}H_{10}$) templates for direct growth of GNRs were prepared on $SiO_2$/Si substrate by FIB-CVD. The GNRs on the templates were synthesized at $900-1,050^{\circ}C$ with introducing $CH_4$ $(20sccm)/H_2$ (10 sccm) mixture gas for 10-300 min. Structural characterizations of the GNRs were carried out using Raman spectroscopy, scanning electron microscopy, and atomic force microscopy.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.309-309
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• 2012

Heteroepitaxial growth remains as one of the continuously growing interests, because the heterogeneous crystallization on different substrates is a common feature in the fabrication processes of many semiconductor materials and devices, such as molecular beam epitaxy, pulsed laser deposition, sputtering, chemical bath deposition, chemical vapor deposition, hydrothermal synthesis, vapor phase transport and so on [1,2]. By using the R.F. sputtering system, ZnO thin films were deposited on graphene 4 and 6 mono layers, which is grown on 400 nm and 600 nm $SiO_2$ substrates, respectively. The ZnO thin layer was deposited at various temperatures by using a ZnO target. In this experimental, the working power and pressure were $3{\times}10^{-3}$ Torr and 50 W, respectively. The base pressure of the chamber was kept at a pressure around $10^{-6}$ Torr by using a turbo molecular pump. The oxygen and argon gas flows were controlled around 5 and 10 sccm by using a mass flow controller system, respectively. The structural properties of the samples were analyzed by XRD measurement. The film surface and carrier concentration were analyzed by an atomic force microscope and Hall measurement system. The surface morphologies were observed using field emission scanning electron microscope (FE-SEM).

• 공업화학
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• 제23권4호
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• pp.405-408
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• 2012

이성분계 이온성액체를 사용하여 다양한 모양의 이산화티타늄 입자를 수정된 졸-겔법을 이용하여 제조하였다. 합성에 사용된 이온성액체의 종류에 따라 이산화티타늄 입자는 다양한 형태를 가지고 있었다. 이는 이온성액체와 유기용매계면 사이에서 형성되는 이산화티타늄이 두 물질 사이의 상호작용에 영향을 받아 입자의 모양이 형성되기 때문이다. 제조된 입자의 광촉매 성능을 측정하기 위하여 4-chlorophenol 분해반응을 실시하였다. 그 결과 1-Octyl-3-methylimidazolium tetrafluoroborate과 1-Octyl-3-methylimidazolium tetrafluoroborate를 이용하여 합성한 $TiO_2$ 입자가 가장 우수한 광촉매 활성을 나타내었다.

• 한국세라믹학회지
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• 제41권7호
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• pp.493-496
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• 2004

The chemical etching of sapphire substrates was peformed to produce smooth surfaces on an atomic scale. The sapphire sur-face etched by using a $H_2$S $O_4$ solution showed a pit-free morphology and was yen smooth as much as $\sigma$$_{rms}$=0.13 nm, that etched by using a mixture of $H_2$S $O_4$ and $H_3$P $O_4$ contained large pits with $\sigma$$_{rms}$=0.34 nm. The $\sigma$$_{rms}$’s and the number of the pits increased with increasing etching temperature. The sapphire etched by using $H_2$S $O_4$ at 32$0^{\circ}C$ had the best surface. These results provide important information on the effects of etching treatment on the structural properties of sapphire for the growth of high-quality epilayers.ayers.

• 한국전기전자재료학회논문지
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• 제28권2호
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• pp.99-103
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• 2015

One-dimensional photonic crystals (1D PCs) were fabricated by RF sputtering technique on p-Si (100), and fused quartz substrates. The 1D PCs structures consisted of $TeO_x$ (x=1.42), and $SiO_2$ with the difference refractive index. In order to estimate the effect on a defect level within 1D PCs structures, samples were prepared with both normal, and defect mode. The structural and optical properties were confirmed by Scanning electron microscope (SEM), and Ultraviolet visible near-infrared spectrophotometer (UV-VIS-NIR) respectively. In the case of a 1D PC normal mode without defect layer, it had a photonic band gap (PBG) in the near infrared (NIR) region. In the case of a 1D PC defect mode with defect layer, it had a sharp transmission band owing to a defect level, and moved towards the longer wavelength after exposing He-Cd laser with a wavelength of 325 nm.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3265-3271
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• 2010

A series of 6,7,8,9-tetrahydro-5H-5-hydroxyphenyl-2-benzylidine-3-substituted hydrazino thiazolo (2,3-b) quinazolines have been synthesized to meet the structural requirements essential for anti-inflammatory and antinociceptive properties. The synthesized series of heterocycles, 6,7,8,9-tetrahydro-5H-5-hydroxyphenyl-2-benzylidine-3-substituted hydrazino thiazolo (2,3-b) quinazoline by the reaction of 6,7,8,9-tetrahydro-5H-5-hydroxy phenyl thiazolo (2,3-b) quinazolin-3(2H)-one with appropriate hydrazine hydrate and ketones/aldehydes in the presence of anhydrous sodium acetate and glacial acetic acid as presented in Scheme 1. Their antinociceptive activity were evaluated by tailflick technique, anti-inflammatory was evaluated by carrageenan-induced paw edema test and their ulcerogenicity index determined by reported protocol. The compounds exhibited the lowest ulcer index ($0.51{\pm}1.63$, $0.48{\pm}1.28$ and $0.50{\pm}1.53$, respectively. The 6,7,8,9-tetrahydro-5H-5-hydroxy phenylhydroxy-2-benzylidine-3-(N'-3-pentylidenehydrazino) thiazolo (2,3-b) quinazoline and 6,7,8,9-tetrahydro-5H-5-hydroxy phenyl-2-benzylidine-3-(N'-2-pentylidene-hydrazino) thiazolo (2,3-b) quinazoline exhibited the most potent antinociceptive and anti-inflammatory activities.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2233-2239
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• 2009

In the present study, firstly, the variations of the geometric parameters induced by different substituents on boroxine skeleton (symmetrically H, $CH_3$, Cl, F, $NO_2$ substituted boroxines) are investigated by using B3LYP/6-31G(d,p), RHF/6-31G(d,p), and MP2/6-31G(d,p) levels of the theory. The second objective is to estimate the substituent effect on the molecular aromaticity of boroxine derivatives using energetic and NICS criteria. Moreover, the effects of different theoretical levels on NICS values have been investigated in a systematic approach. Lastly, a rotational analysis has been performed to investigate the effect of rotation around the B-Me and B-$NO_2$ bonds on total energy of the system. It has been found that electron withdrawing substituents contribute the aromaticity of boroxine affirmatively. Conversely, electron donors make the system less aromatic. Also, the theoretical vibrational spectra for these boroxine derivatives are presented and compared with the experimental data from the literature.

• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1539-1544
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• 2007

1-Phenyl-3-p-fluorophenyl-5-p-chlorophenyl-2-pyrazoline has been synthesized and characterized by elemental analysis, IR, UV-Vis and X-ray single crystal diffraction. Density functional calculations show that B3LYP/6-311G** method can reproduce the structural parameters. The electronic absorption spectra have been predicted based on the optimized structure by using 6-311G** and 6-311++G** basis sets and compared with the experimental values. The results indicate that TD-DFT method can only predict the electronic absorption spectra of the system studied here approximately. On the basis of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between ,C0p,m,S0m,H0m and temperature.