• 한국표면공학회지
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• 제29권6호
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• pp.788-796
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• 1996

$TiO_2$ films prepared by RF magnetron sputtering, electron beam evaporation, ion assisted deposition (IAD) and sol-gel method are prepared on c-Si substrate and vitreous silica substrate respectively. From the transmission spectra of $TiO_2$ films on vitreous silica substrate in the spectral region from 190 nm to 900 nm, k($\lambda$) of $TiO_2$ is obtained. Using k($\lambda$) in the interband transition region the coefficients of the quantum mechanical dispersion relation of an amorphous $TiO_2$ and hence n($\lambda$) including the optically opaque region of above fundamental transition energy are obtained. The spectroscopic ellipsometry spectra of $TiO_2$ films in the spectral region of 1.5-5.0eV are model analyzed to get the film packing density variation versus i) substrate material, ii) film thickness and iii) film growth technique. The complex refractive index change of these $TiO_2$ films versus water condensation is also studied. Film micro-structures by SE modelling results are compared with those by atomic force microscopy images and X-ray diffraction data.

• 접착 및 계면
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• 제21권4호
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• pp.143-155
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• 2020

Sol-Gel 공정을 통해서 제조되는 유-무기 하이브리드 화합물들은 방청 코팅, 방빙 코팅(Anticing), 자가 세정 코팅, 반사 방지 코팅 등과 같은 기능성 코팅 재료로 널리 사용되어져 왔다. 특히 소수성 코팅 표면을 제조하기 위해서는 코팅표면의 표면에너지가 낮고 코팅 표면의 조도를 제어가 요구된다. 표면에너지와 표면 조도를 조절하는 전형적인 공정은 in-situ fabrication 공정, 'Pre-fluorinating/Post-roughening', 'Pre-roughening/ Post-fluorinating이다. 본 연구에서는 in-situ fabrication 공정인 Particle-Binder 공정을 이용해서 소수성 코팅표면을 제조하였다. 3관능기 유기실란화합물과 불소 함유 유기실란 화합물과의 가수분해 및 축합반응을 통해 제조된 불소함유 유-무기 하이브리드를 바인더로 사용하여서 무기물 나노입자와 혼합하여 소수성 코팅액을 제조하고 유리 기재 위에 스핀코팅 후 열건조하여서 코팅막을 제조하였다. 바인더인 유-무기 하이브리드 화합물의 불소 함유 실란화합물의 첨가량, 첨가순서, 무기물 나노입자 첨가량에 따른 코팅막의 물성 변화를 조사하였다. 분석결과 불소 함량이 10 wt%인 유-무기 하이브리드 화합물(GPTi-HF10)을 바인더로 사용하여서 제조된 코팅막이 가장 소수성이 우수하였으며 수접촉각은 (107.52 ± 1.6°), 이 바인더와 무기물 나노입자의 무게비가 1:3인 경우(GPTi-HF10-MS 3.0)에 가장 높은 수접촉각(130.84±1.99°)을 나타내었다.

• 한국농촌건축학회논문집
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• 제21권2호
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• pp.35-42
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• 2019

There are 17,427 reservoirs in Korea, of which about 96% were built before the mid 1980s. Therefore, aging is severe and reinforcement are necessary. In addition, aged reservoirs, which are more than 50 years old, account for 70% of the total. Therefore, there is a problem such as the collapse of the reservoir and the decrease of the storage capacity due to progress of aging with time. The grouting method using cement is mainly used as maintenance and reinforcement method of old reservoir. However, the grouting method using cement has engineering and environmental problems. In order to solve the engineering and environmental problems of cement grouting method, an eco-friendly grouting material was developed that mixes circular resource grouting binder, high molar ratio sodium silicate and colloidal silica. The engineering and environmental properties of the developed injection materials were evaluated by conducting gel time, homo-gel strength, sea water resistance test and environmental stability evaluation. Also, examined the possibility of replacing OPC existing aged reservoir reinforcement methods. As a result, it was found out that it was better than the conventional cement method in terms of engineering and environment. However, since this study is the result of laboratory test, it is necessary of verify the application at field of aged reservoir.

• Membrane and Water Treatment
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• 제5권3호
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• pp.171-182
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• 2014

Organic compounds are adsorbed on RO/NF membranes, and the adsorption may influence the rejection of organic compounds by the membranes. Because almost RO/NF membranes are composite membranes, the results obtained by adsorption experiment with using membrane pieces are unable to avoid the influence by the support membrane. In this work, the interaction between membrane polymer and organic solutes was examined by an inverse HPLC methodology. Poly (m-phenylenetrimesoylate), the constituent of skin layer of RO/NF membranes, was coated on silica gel particles and used as a stationary phase for HPLC. When water was used as a mobile phase, almost hydrophilic aliphatic compounds were not effectively adsorbed on the stationary phase, although hydrophobic compounds were slightly adsorbed. The results indicated that the hydrophilic aliphatic compounds are useful probe solutes to examine the molecular sieving effect of a membrane. When water was used as a mobile phase, the aromatic compounds were strongly retained, and therefore $CH_3CN/H_2O$ (30/70) was used as a mobile phase. It was revealed that the adsorption of aromatic compounds was controlled by stacking between solute and polymer and was hindered by non-planar structure and substituents.

• Applied Biological Chemistry
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• 제51권3호
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• pp.153-158
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• 2008

토양으로부터 tyrosinase 저해제를 생산하는 방선균 F-97을 분리하여, 이 균이 생산하는 tyrosinase 저해제를 정제하였다. 먼저 배양액을 원심분리하고 이 여액을 pH 4.0으로 조절한 후 IRC-120($NH_4^+$ type column chromatography, Silica gel column chromatography, C18 column chromatography, Sephadex LH-20 column chromatography를 사용하여 정제하였다. 정제도 확인은 ODS HPLC를 이용하여 확인하였으며, 최종 정제 수율은 5.24%이었다. 물리 화학적 특성으로 tyrosinase 저해제는 water, methanol, ethanol 등에는 잘 녹았으나, acetone, butanol, ethylacetate, chloroform 등에는 녹지 않는 수용성 물질이었다. 물을 용매로 UV 흡광도를 측정한 결과 194nm에서 최대 흡광도를 나타내었다. 본 tyrosinase 저해제는 Iodine, Ninhydrin, Millon, Sakaguchi, Xanthoproteic, Emerson 시험에서는 음성이었고, Molish, Benedict, conc. $H_2SO_4$, $KMnO_4$ 시험에서는 양성이었다. 저해제의 열 안정성은 $100^{\circ}C$ 50분까지 안정하였고, pH $4{\sim}9$에서 안정하였다. Tyrosinase 저해제의 mushroom tyrosinase에 대한 $IC_{50}$ 값은 $19.2{\mu}g/ml$이었고, Streptomyces bikiniensis NRRL B-1049에 대한 저해활성은 $1,000{\mu}g/ml$ 일 때 27mm이었다. 그리고 본 저해제의 저해 양상은 경쟁적 저해로 확인되었다.

• 한국식품과학회지
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• 제37권1호
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• pp.78-83
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• 2005

신선초에서 항산화 활성 물질을 분리하기 위해 신선초를 80% 에탄올 추출하고 추출물에 대한 계통 분획을 실시하여 n-hexane, chloroform, ethyl acetate, n-butanol 및 water의 총 5가 분획으로 나누어 항산화 활성을 측정한 결과 ethyl acetate 분획의 활성이 가장 높아 ethyl acetate 분획물로부터 항산화 활성 물질을 분리 정제하였다. Silica gel column chromatography를 통하여 chloroform : methanol : water의 용매 조건을 점차적으로 변경하면서 소분획으로 나누고 항산화 활성이 가장 높은 소분획에 대해서 acetylation 반응을 실시하고 이를 n-hexane : ethyl acetate : methanol의 용매 조건으로 단일 물질로 분리 한후 deacetylation 반응을 거쳐 최종 두 개의 단일 화합물을 획득했다. 두 개의 단일 화합물에 대한 구조 해석을 기기분석을 통해서 진행 한 결과 이 두 화합물을 각각 isoquercitrin과 hyperoside로 최종 동정하였다. Isoquercitrin과 hyperoside에 대한 항산화 활성을 DPPH radical 소거법, ABTS radical 소거법, OH radical 소거법 및 $H_{2}O_{2}$ 소거법으로 측정한 결과 4가지 assay법에 대해서 저농도에서 고른 항산화 활성을 나타냈고, 또한 DNA 손상에 대한 보호 효과를 측정한 결과 isoquercitrin과 hyperoside 모두 손상된 DNA에 대한 보호 효과를 나타내는 것을 확인할 수 있었다. 따라서 isoquercitrin과 hyperoside는 DPPH radical 소거능과 ABTS radical 소거능과 같은 기본적인 항산화 활성과 더불어 DNA 손상에 직접적인 영향을 미치는 OH radical과 $H_{2}O_{2}$에 대해서 높은 항산화 활성을 나타내면서 동시에 DNA 손상에 대한 보호 효과를 나타냄으로써 다양한 경로의 항산화 메커니즘에 작용한다는 사실을 유추해 볼 수 있으며 산업적으로 유용한 소재로서의 연구가 가능할 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2178-2182
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• 2011

Recently, the synthesis of ordered macroporous materials has received much attention due to its potential use as photonic band gap materials.$^1$ In this study, we have used the three-dimensional (3D) latex array template impregnated with benzenesulfonic acid (BSA), which is capable of catalyzing the reaction using tetraethyl orthosilicate (TEOS) as a precursor and distilled water. The polystyrene (PS) templates were reacted with TEOS in $scCO_2$ at 40 $^{\circ}C$ and at 80 bar. In the reactor, TEOS was filtrated into the PS particle lattice. After the reaction, porous silica materials were obtained by calcinations of the template. The stability test of the PS template in pure $CO_2$ was conducted before the main experiment. Scanning electron microscopy (SEM) images showed that the reaction in $scCO_2$ takes place only on the particle surface. This new method using $scCO_2$ has advantages over conventional sol-gel processes in its capability to control the fluid properties such as viscosity and interfacial tension. It has been found that the reaction in $scCO_2$ occurs only on the particle surface, making the proposed technique as more rapid and sustainable method of synthesizing inverse opal materials than conventional coating processes in the liquid phase and in the vapor phase.

• Parasites, Hosts and Diseases
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• 제21권1호
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• pp.21-26
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• 1983

As a series of studios on the suitability as a second intermediate host of Clcnorchis sinensis, the wormicidal effects of mucus from epidermis of Cyprinus carpio nudus were observed. The results obtained were sumlnarized as follows : On the silica gel thin layer chromatography with the greenisll yellow supernatant in acetone: benzene110:90 as carrier, seven spots were observed in iodine chamber. The spot of Rf. 0.225 value among them disclosed the strongest wormicidal effect on the cercaria, the encysted metacercaria, and the adult of C. sinensis. hfeanwhile, no seasonal variations were found in Rf. values and effect of the wormicidal fractions. The wormicidal materials in epidermal mucus of C. carpio nudes and Carassius carassius were compared in their effect, and the former was Inore effective killing substance than the latter. It seemed that C. carpio nodus could not be proper intermediate host of C. sinensis according to results of the present study, in addition to our previous observation results.

• Journal of Microbiology and Biotechnology
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• 제6권3호
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• pp.184-188
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• 1996

The Acinetobacter sp. BE-254 isolated from soil sources produced a bioemulsifier in the medium supplemented with n-hexadecane. This bioemulsifier was purified by the procedures of fractionation (ammonium sulfate and chilled acetone), extraction by hexane, and column chromatography on silica gel 60. The results from various color reactions indicated that the bioemulsifier was a glycolipid. The purified emulsifier was very stable at pHs ranging from 4 to 10 and under heat treatment at $100^{\circ}C$ for 30 min. Emulsification activity was also hardly influenced by pH. The critical micelle concentration (CMC) and surface tension at the point ($\gamma_{cmc}$) of the bioemulsifier were approximately 35 mg/l and 30 mN/m, respectively. The bioemulsifier showed a fairly good emulsification activity and stability in comparison with other commercial emulsifiers in the basic formula composed of emulsifier, oil, and water.

• 동의생리병리학회지
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• 제22권4호
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• pp.903-906
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• 2008

Woodfordia fruticosa Kurz (Lythraceae) is used in the treatment of various ailments in traditional medicines. DPPH activity guided fractionation and purification process was used to identify the free radical-scavenging components from the flowers of this plant. The methanolic extract of the plant was first fractionated into four extracts; namely, n-hexane, chloroform, ethyl acetate and water fractions. Among them, the ethyl acetate fraction was found to be the most effective and was further subjected to activity guided-fractionation and isolation procedures. After successive column chromatography on silica gel and Sephadex LH-20, gallic acid, which is responsible for the radical scavenging activity, was isolated and its structure was elucidated by spectral methods ($^1H$ NMR, $^{13}C$ NMR) and by comparison with literature.