• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.410-410
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• 2009

현재 탄소나노튜브 (carbon nanotube, CNT)를 여러 분야에 응용하기 위해 다양한 연구가 진행되고 있다. 본 논문에서는 단일벽 CNT (single-walled CNT)를 여러 가지 계면활성제로 최적 분산시킨 수용액으로부터 제조한 투명 전도성 필름을 터치스크린이나 디스 플레이 소자에 응용할 목적으로 필름의 전기저항 및 광 투과도를 향상시키기 위한 연구를 수행하였다. 우선 계면활성제로 분산시킨 정량의 CNT 수용액을 알루미나 재질의 필터에서 진공 필터링하여 CNT 필름을 제조하였다. 알루미나 필터를 sodium hydroxide (NaOH) 수용액으로 용해시켜 제거하여 얻은 CNT 필름을 유리기판 위에 부착시켰다. 필름의 전기저항을 낮추기 위해 유리기판 위에 부착된 CNT 필름을 질산($HNO_3$) 용액으로 처리하였다. Scanning electron microscopy, UV-Vis spectroscopy를 이용하여 각각 필름의 형상과 광투과도를 분석하였고, 4-point probe로 면 저항을 측정하였다. 계면활성제로 분산시킨 대부분의 CNT 필름의 면 저항은 질산 처리에 의해 감소하였다. 이는 CNT 표면에 코팅되어 있던 계면활성제가 질산에 의해 제거되었기 때문인 것으로 예상된다. 그리고 anionic 계면활성제를 이용한 필름이 대체로 낮은 면 저항을 보였고, 그중 분산력이 가장 좋은 sodium dodecyl benzenesulfonate(SDBS)가 최저의 면 저항을 나타내었다. 질산처리에서 Polyvinyl pyrrolidone(PVP)과 cetyltrimethylammonium bromide(CTAB)를 사용하여 제조한 CNT 필름의 면 저항이 가장 뚜렷한 감소를 보였다.

• Journal of Korean Medicine Rehabilitation
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• v.24 no.2
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• pp.31-40
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• 2014

Objectives Trachelospermi caulis, known as Nak-Suk-Deung in Korea, is the dried leafy stem of Trachelospermum asiaticum var. intermedium Nakai, and climbing stems and branches of Trachelospermum sdisyivum var, intermedium nakai or Apocyanaceae. Trachelospermi caulis has antipyretic and analgesic activity. It has traditionally been used as a folk remedy in Korea for the treatment of various infla mMatory diseases, including rheumatoid arthritis. The purpose of this study was to evaluate the Effects of Trachelospermum caulis extract on SNP-induced infla mMatory responses in rabbit HIG-82 synovial membrane cells. Methods Anti-infla mMatory effects of the extract of Trachelospermum caulis were investigated using rabbit HIG-82 synovial membrane cells. For this study, 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, western blot analysis, PGE2 i mMunoassay, and NO detection were conducted. Results The aqueous extract of Trachelospermum caulis exerted cytotoxicity and suppressed PGE2 synthesis and NO production in rabbit HIG-82 synovial membrane cells. The aqueous extract of Trachelospermum caulis also inhibited the SNP-induced expressions of COX-2, iNOS, and TNF-$\alpha$ in rabbit HIG-82 synovial membrane cells. Conclusions These results showed that the extract of Trachelospermum caulis exerts the anti-infla mMatory effect by suppressing COX-2, iNOS, and TNF-$\alpha$ expressions in the synovial membrane cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.396-396
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• 2008

투명 전도성 탄소나노튜브(carbon nanotube, CNT) 필름을 터치스크린이나 디스플레이 소자 등의 전극에 응용할 목적으로, CNT 필름의 전기저항 및 광 투과도를 향상시키기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 단일벽 CNT (single-walled CNT)를 여러 가지 계면활성제로 분산시킨 수용액으로부터 제조한 CNT 필름을 산 처리하여 저항 및 투과도의 변화를 관찰하였다. 우선 계면활성제로 분산시킨 CNT 수용액을 알루미나 재질의 필터에서 정량적으로 진공 필터링하여 CNT 필름을 제조하였다. 알루미나 필터를 sodium hydroxide (NaOH) 수용액으로 용해시켜 제거함으로써 얻은 CNT 필름을 유리기판 위에 부착시킨 후 광 투과도와 먼 저항 (sheet resistance)을 측정하였다. CNT 필름을 질산 ($HNO_3$) 용액에 처리하였을 때 투과도는 1~5 % 향상되었으며, 면 저항은 계면활성제로 분산시킨 CNT 필름 대부분에서 감소하였다. 이는 CNT 표면에 코팅되어 있던 계면활성제들이 산에 의해 제거되었기 때문일 것으로 추측된다. 특히 sodium dodecylbenzene sulfonate (NaDDBS)로 제조한 CNT 필름의 경우, 질산을 처리 전에는 투과도 83%, 면 저항 450 $\Omega$/sq.의 특성을 보였으나, 처리 후에는 각각 86 %, 350 $\Omega$/sq.로 향상되었다. Polyvinyl pyrrolidone (PVP)과 cetyltrimethylammonium bromide (CTAB)를 사용하여 제조한 CNT 필름의 면 저항이 가장 뚜렷한 감소를 보였다. 제조된 필름과 삼 처리된 필름 특성을 Raman spectroscopy, scanning electron microscopy, UV-Vis spectroscopy 등을 이용하여 분석하였고, 4-point probe로 면 저항을 측정하였다.

• Restorative Dentistry and Endodontics
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• v.40 no.4
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• pp.290-298
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• 2015

Objectives: Sodium hypochlorite (NaOCl) is an excellent bactericidal agent, but it is detrimental to stem cell survival, whereas intracanal medicaments such as calcium hydroxide ($Ca[OH]_2$) promote the survival and proliferation of stem cells. This study evaluated the effect of sequential NaOCl and $Ca(OH)_2$ application on the attachment and differentiation of dental pulp stem cells (DPSCs). Materials and Methods: DPSCs were obtained from human third molars. All dentin specimens were treated with 5.25% NaOCl for 30 min. DPSCs were seeded on the dentin specimens and processed with additional 1 mg/mL $Ca(OH)_2$, 17% ethylenediaminetetraacetic acid (EDTA) treatment, file instrumentation, or a combination of these methods. After 7 day of culture, we examined DPSC morphology using scanning electron microscopy and determined the cell survival rate with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. We measured cell adhesion gene expression levels after 4 day of culture and odontogenic differentiation gene expression levels after 4 wk using quantitative real-time polymerase chain reaction. Results: DPSCs did not attach to the dentin in the NaOCl-treated group. The gene expression levels of fibronectin-1 and secreted phosphoprotein-1 gene in both the $Ca(OH)_2$- and the EDTA-treated groups were significantly higher than those in the other groups. All $Ca(OH)_2$-treated groups showed higher expression levels of dentin matrix protein-1 than that of the control. The dentin sialophosphoprotein level was significantly higher in the groups treated with both $Ca(OH)_2$ and EDTA. Conclusions: The application of $Ca(OH)_2$ and additional treatment such as EDTA or instrumentation promoted the attachment and differentiation of DPSCs after NaOCl treatment.

• Journal of Microbiology and Biotechnology
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• v.31 no.3
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• pp.439-446
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• 2021

Quercus infectoria (nutgall) has been reported to possess antimicrobial activities against a wide range of pathogens. Nevertheless, the biofilm removal effect of nutgall extract has not been widely investigated. In this study, we therefore evaluated the effect of nutgall extract in combination with cetrimonium bromide (CTAB) against preformed biofilm of Salmonella Typhimurium on polypropylene (PP) and stainless steel (SS) coupons in comparison with other sanitizers. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of nutgall extract and surfactants (CTAB and sodium dodecyl sulfate; SDS) were assessed. CTAB showed a more efficient antimicrobial activity than SDS and was selected to use in combination with nutgall extract for removing biofilm. To determine the biofilm removal efficacy, the PP and SS coupons were individually submerged in 2x MBC of nutgall extract (256 mg/ml) + 2x MBC of CTAB (2.5 mg/ml), nutgall extract alone (256 mg/ml), CTAB alone (2.5 mg/ml), distilled water, and 100 ppm sodium hypochlorite for 5, 15, and 30 min. The remaining sessile cells in biofilm were determined. Overall, the greatest biofilm removal efficacy was observed with nutgall extract + CTAB; the biofilm removal efficacy of sanitizers tended to increase with the exposure time. The SEM analysis demonstrated that S. Typhimurium biofilm on PP and SS coupons after exposure to nutgall extract + CTAB for 30 min displayed morphological alterations with wrinkles. This study suggests nutgall extract + CTAB may be an alternative to commonly used sanitizers to remove biofilm from food contact surfaces in the food industry and household.

• Journal of Powder Materials
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• v.29 no.3
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• pp.207-212
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• 2022

Nanosized rutile titanium dioxide (TiO₂) is used in inorganic pigments and cosmetics because of its high whiteness and duality. The high quality of the white pigments depends on their surface coating technique via the solgel process. SiO₂ coatings are required to improve the dispersibility, UV-blocking, and whiteness of TiO₂. Tetraethyl orthosilicate (TEOS) is an important coating precursor owing to its ability to control various thicknesses and densities. In addition, we use Na₂SiO₃ (sodium silicate) as a precursor because of its low cost. Compared to TEOS, which controls the pH using a basic catalyst, Na₂SiO₃ controls the pH using an acid catalyst, giving a uniform coating. The coating thickness of TiO₂ is controlled using a surface modifier, cetrimonium bromide, which is used in various applications. The shape and thickness of the nanosized coating layer on TiO₂ are analyzed using transmission electron microscopy, and the SiO₂ nanoparticle behavior in terms of the before-and-after size distribution is measured using a particle size analyzer. The color measurements of the SiO₂ pigment are performed using UV-visible spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.263-266
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• 2004

A sensitive, selective and rapid method has been developed for the determination ${\mu}$g/L level of vanadium ion based on the rapid reaction of vanadium(V) with 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP) and the solid phase extraction of the colored chelate with $C_{18}$ cartridge. The QADEAP reacts with V(V) in the presence of citric acid-sodium hydroxide buffer solution (pH = 3.5) and cetyl trimethylammonium bromide (CTMAB) medium to form a violet chelate of a molar ratio 1 : 2 (V(V) to QADEAP). This chelate was enriched by solid phase extraction with $C_{18}$cartridge and the enrichment factor of 50 was obtained by elution of the chelates from the cartridge with ethanol. The molar absorptivity of the chelate is $1.28 {\times}10^5L\;mol^{-1}cm^{-1}$ at 590 nm in the measured solution. Beer's law is obeyed in the range of 0.01-0.6 ${\mu}$g/mL. The detection limit is 0.04 ${\mu}$g/L in the original samples. This method was applied to the determination of vanadium(V) in water and biological samples with good results.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.726-736
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• 2004

In this paper, kinetics of reaction between Bromophenol blue (BPB) and $OH^-$, called fading, has been studied through a spectrophotometric method in the presence of nonionic Triton X-100 (TX-100), anionic sodium dodecyl sulfate (SDS) and cationic dodecyl trimethylammonium bromide (DTAB) surfactants. The influence of changes in the surfactant concentration on the observed rate constant was investigated. The results are treated quantitatively by pseudophase ion-exchange (PPIE) model and a new simple model called "classical model". The binding constants of BPB molecules to the micelles and free molecules of surfactants, their stoichiometric ratios and thermodynamic parameters of binding have been evaluated. It was found that SDS has nearly no effect on the fading rate up to 10 mM, whereas TX-100 and DTAB interact with BPB which reduce the reaction rate. By the use of fading reaction of BPB, the binding constants of SDS molecules to TX-100 micelles and their Langmuir and Freundlich adsorption isotherms were obtained and when mixtures of DTAB and TX-100 were used, no interaction was observed between these two surfactants.

• Korean journal of food and cookery science
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• v.25 no.3
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• pp.379-386
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• 2009

The antimutagenic and cytotoxic activities of ethanol and water extracts from Rubus coreanum were investigated in this study. Their antimutagenic activities were measured by the Ames test and their cytotoxic activities were evaluated by the growth inhibition of cancer cells via the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay and the sulforhodamine B (SRB) assay. In the results, the inhibition rates of the ethanol and water extracts toward mutagenicity induced by 4-NQO were 95.0% and 93.6% at 5 mg/plate, respectively, while their inhibition rates against mutagenicity induced by sodium azide were 27.2% and 40.8%, respectively. According to MTT assay, the cytotoxicity values of the ethanol extract against Hep3B and HeLa cells were 67.2% and 68.5%, respectively, and the values for the water extract were 65.8% and 66.4%, respectively. In the SRB assay, the ethanol and water extracts inhibited over 60% of cancer cell growth. In conclusion, both the ethanol and water extracts of Rubus coreanum offer potentially good antimutagenic and anticancer effects.

• Journal of the Korean Home Economics Association
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• v.25 no.4
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• pp.9-18
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• 1987

This study is conducted to investigate the influence of addition of quarternary ammonium salt(cetyl trimethyl ammonium bromide: CTAB) when polyester(PET) fabric is treated with sodium hydroxide(NaOH), depending on experimental variables such as CTAB concentration, NaOH concentration, time & temperature, and the change in physical & chemical properties of alkaline-hydrolyzed PET fabrics depending on their weight loss. The results are as follows: 1. By adding CTAB in aqueous NaOH, the weight loss of PET fabric is increased remarkably and until the concentration of CTAB is reached at its cmc, and the higher the concentration of CTAB are, the more weight loss on PET fibrics are. 2. The addition of CTAB in aqueous NaOH is most effective at lower NaON concentration(2%) among various NaOH concentration, on increasing the amount of weight loss, while there are almost similar results through various treatment time and temperature. 3. As the amount of weight of weight loss on PET fabric is increased, the increase of void space in the PET yarn, of softness & dyeability of PET fabric and the decrease of tensile strength are found. On the other hand, the moisture regain shows a little increase by alkaline-hydrolysis on PET fabric while vertical absorption test & water retention value are not sufficiently sensitive to distinguish between the hydrophillicity of untreated and treated PET fabric. The shrinkage of PET fabric is induced by swelling in hot aqueous NaOH regardless of NaOH concentration & addition of CTAB.