• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.771-776
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• 2017

The cover glass of mobile displays and photovoltaic cells needs a functional coating, such as an anti-reflection and self-cleaning coating. Numerous studies have been conducted on the engineering application of biomimetic functional surfaces, such as moth eye and lotus leaf Anti-reflection coantings of silica nanoparticles could enhance the light transmittance. $TiO_2$ photocatalyst coatings have been applied to self-cleaning functional films. In this study, transparent hydrophobic anti-reflective coatings consisting of thin layers of $SiO_2/TiO_2$ nanoparticles were fabricated on a slide glass substrate by the sol-gel process and dip-coating process. The dependence of the surface morphology of the functional coatings was investigated by the atomic force microscopy (AFM), contact angle measurement, and UV-visible spectroscopy. It was found that the coating of $TiO_2$ nanoparticles exhibited a high average transmittance comparable to that of the bare slide glass substrate in the visible light range. The bi-layered functional coating of 7 nm $SiO_2$/7nm $TiO_2$ nanoparticles exhibits a transparent hydrophobic surface with a contact angle of $110^{\circ}$ and an improvement of the average transmittance of 2.3% compared to the bare slide glass substrate in the visible light range.

• Journal of Environmental Science International
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• v.20 no.1
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• pp.119-126
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• 2011

In this study, reaction model and reactions rate accelerated by o-iodosobenzoate ion(IB$^{\ominus}$) on hydrolysis reaction of p-nitrophenyl valate(NPV) using ethyl tri-octyl ammonium mesylate(ETAMs) for quaternary ammonium salts, the phase transfer catalysis(PTC) reagent, were investigated. The effect of IB$^{\ominus}$ on hydrolysis reaction rate constant of NPV was weak without ETAMs solutions. Otherwise, in ETAMs solutions, the hydrolysis reactions exhibit higher first order kinetics with respect to the nucleophile, IB$^{\ominus}$, and ETAMs, suggesting that reactions are occurring in small aggregates of the three species including the substrate(NPV), whereas the reaction of NPV with OH$^{\ominus}$ is not catalyzed by ETAMs. Different concentrations of NPV were tested to measure the change of rate constants to investigate the effect of NPV as substrate and the results showed that the effect was weak. This means the reaction would be the first order kinetics with respect to the nucleophile. This behavior for the drastic rate-enhancement of the hydrolysis is referred as 'Aggregation complex model' for reaction of hydrophobic organic ester with o-iodosobenzoate ion(IB$^{\ominus}$) in hydrophobic quarternary ammonium salt(ETAMs) solutions.

• Macromolecular Research
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• v.16 no.4
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• pp.367-372
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• 2008

We fabricated tetra(5-n-nonyl-8-tert-butyl-2,3-pyrazino[2,3-b]indolo)porphyrazinato copper(II) (Cu-Pc-$C_8$) Langmuir-Blodgett (LB) films. We further investigated the influence of arachidic acid (AA) as a transfer promoter, as well as the effect of dipping speed, on the deposition of the films on hydrophilic and hydrophobic substrates. In the case of pure Cu-Pc-$C_8$ LB deposition on a hydrophilic substrate, the transfer ratio was close to one for up-stroke depositions, but the previously deposited film was peeled off and re-spread onto water at down-stroke depositions. Whereas the stability of the Cu-Pc-$C_8$ LB films was not improved by AA addition on hydrophilic substrates, the deposition of Cu-Pc-$C_8$ was significantly improved by the presence of AA on a hydrophobic substrate. The AA-assisted deposition had transfer ratio of close to 1 and was essentially stable up to 10-layer depositions. Comparison of the UV-visible spectrum of a Cu-Pc-$C_8$/AA LB film with that of Cu-Pc-$C_8$/AA solution in dichloroethane revealed that the Soret and Q bands for the Cu-Pc-$C_8$/AA LB film were broadened and red-shifted due to the aggregation of phthalocyanines upon assembly in the LB film.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.354-359
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• 2006

Recently, the interest in lithography without photo exposure has been increased compare to the conventional photolithography in nano meter and micrometer size patterning area. We studied a self aligned dipping of Ag solution through micro contact printing (${\mu}-CP$) with octadecyltrichlorosilane (OTS) treated polydimethylsiloxane (PDMS) soft mold. The OTS monolayer on the patterned PDMS was formed by dipping it into OTS solution. We transferred the OTS monolayer from PDMS mold to the glass. The OTS monolayer changed the surface energy from hydrophilic surface to hydrophobic surface, And then we made self aligned Ag solution patterns just after dipping the substrate, using adhesion difference of Ag solution between OTS treated hydrophobic area and non-OTS treated hydrophilic area. We finally get the Ag patterns through only dip-coating after the ${\mu}-CP$ process. And we observed surface energies on the glass substrate through the contact angle measurements as time goes on.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.2
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• pp.103-108
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• 1998

A hydrophobic substrate triolein was hydrolyzed by lipase in a mono-phase reaction system containing cyclodextrin(CD) as emulsifier. The triolein was transformation to an emulsion-like state in the CD containing reaction system in contrast to the oil-droplet like state without CD due to the formation of an inclusion complex between the lipids and CDs. The hydyrolysis reaction increased substantially in the CD containing reaction system, and the optimum reaction conditions including the amount of lipase, ${\beta}$-CD concentration, and mixing ratio of triolein and ${\beta}$-CD, were determined. The performance of the enzyme reaction in a mono-phase reaction system was compared with that of a two-phase reaction system which used water immiscible hexane as the organic solvent. The role of a CD in the mono-phase reaction system was elucidated by comparing the degree of the inclusion complex formation with triolein and oleic acid, Km and Vmax values, and product inhibition by oleic aicd in aqueous and CD containing reaction systems. The resulting enhanced reaction seems to be caused by two phenomena; the increased accessibility of lipase to triolein and reduced product inhibition by oleic acid through the formation of an inclusion complex.

• Journal of Environmental Science International
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• v.15 no.5
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• pp.485-491
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• 2006

In the aqueous solutions the dephosphorylations of isopropyl phenyl-4-nitrophenyl phosphinate(IPNPIN) mediated by hydroxide$(OH^{\theta})$ and o-iodosobenzoate$(IB^{\theta})$ ions ate relatively slow, because of hydrophobicity of the substrate, and however it appears that $OH^{\theta}$ is inherently better nucleophile than $IB^{\theta}$, which is more soft ion. On the other hand, in cetyltrimetyiammonium bromide(CTABr) solutions which contain cationic micelles, the dephosphorylations of IPNPIN mediated by $OH^{\theta}$ or $IB^{\theta}$ ate very accelerated to 120 or 100,000 times as compared with those in the aqueous solutions. The values of pseudo first order rate constants reach a maximum with increasing. Such rate maxima are typical of micellar catalysed bimolecular reactions and the rise in rate constant followed by a gradual decrese is characteristic of reactions of hydrophobic substrates. In the cationic micellar solutions of CTABr, $IB^{\theta}$ accelerates the reactions much more than that $OH^{\theta}$ does. The reason seems that $IB^{\theta}$ which is more hydrophobic and soft ion than $OH^{\theta}$ is more easily moved into the Stern layer of the CTABr micelles than $OH^{\theta}$. In the anionic micellar solutions of sodium dodecyl sulfate(SDS), the dephosrhorylations of IPNPIN ate slower than those in aqeous solutions. It means that $OH^{\theta}$ or $IB^{\theta}$ cannot easily move and approach to the Stern layer of the micelle in which almost all the hydrophobic substrate are located and which has a negative circumstance.

• Korean Journal of Materials Research
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• v.24 no.12
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• pp.689-693
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• 2014

Anti-reflection coating films have used to increase the transmittance of displays and enhance the efficiency of solar cells. Hydrophobic anti-reflection coating films were fabricated on a glass substrate by sol-gel method. To fabricate an anti-reflection film with a high transmittance, poly ethylene glycol (PEG) was added to tetraethyl orthosilicate (TEOS) solution. The content of PEG was changed from 1 to 4 wt% in order to control the morphology, thickness, and refractive index of the $SiO_2$ thin films. The reflectance and transmittance of both sides of the coated thin film fabricated with PEG 4 wt% solution were 0.3% and 99.4% at 500 nm wavelength. The refractive index and thickness of the thin film were n = 1.29 and d = 105 nm. Fluoro alkyl silane (FAS) was used for hydrophobic treatment on the surface of the anti-reflection thin film. The contact angle was increased from $13.2^{\circ}$ to $113.7^{\circ}$ after hydrophobic treatment.

• Korean Journal of Microbiology
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• v.26 no.1
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• pp.52-59
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• 1988

A partially purified preparation of L-galactonolactone oxidase which catalyzes the last step of L-ascorbic acid biosynthesis was obtained from Saccharomyces cerevisiae ATCc 26787. The purification procedures included Triton X-100 treatment, protamine sulfate precipitation, ammonium sulfate precipitation, DEAE-Sepharose CL-6B ion exchange chromatography, Sephadex G-150 gel filtration chromatography, and Phenyl-Sepharose CL-4B hydrophobic interaction chromatography. The optimum temperature for the enzyme activity was about $34^{\circ}C$ and the optimum pH was 6.8-7.0. The substrate specificity was confined to L-aldonolactones, L-galactono-1,4-lactone and L-gulono-1,4-lactone. An apparent Km value of 0.294mM with L-galactono-1,4-lactone as a substrate was found. By comparing the substrate specificities of this enzyme with those of isofunctional enzymes of higher plants and animals, it becomes evident that the enzyme of S. cerevisiae ATCC 26787 is rather similar to the L-gulonolactone oxidase of animals than the galactonolactone dehydrogenase of higher plants.

• Journal of Sensor Science and Technology
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• v.30 no.3
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• pp.185-189
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• 2021

Herein, we propose a functional polymer cantilever to enhance maturation and contractile force of cardiomyocytes. The proposed cantilever consists of a surface-patterned polymer substrate and silver nanowires (AgNWs). The AgNWs are transferred to the PDMS substrate using conventional molding techniques. This thin metallic surface significantly improves the adhesion of cardiomyocyte on the surface-patterned PDMS with the hydrophobic characteristics. In addition, the use of AgNWs improves the visibility of the conducting PDMS substrate for the observation of cardiomyocyte through an inverted microscope. The AgNWs also assist in synchronizing each cardiomyocyte to maximize its contractile force.

• Journal of Pharmaceutical Investigation
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• v.37 no.3
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• pp.131-135
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• 2007

A previous report recently demonstrated that ultrasound-induced hyperthermia (USHT:0.4 watts (W)/$cm^2$ at $41^{\circ}C$) could increase cellular uptake of P-glycoprotein (P-gp) substrates in P-gp expressing cancer cell lines. Since P-gp plays a major role in limiting drug permeability in the multi-drug resistant (MDR) cells, studies were conducted to elucidate the mechanism of USHT on cellular accumulation of P-gp and non-P-gp substrate in MDR cells. To accomplish this aim, we studied the effects of USHT on the accumulation of P-gp substrate, R123 and non-P-gp substrate, antipyrine in MDR cells. We demonstrated that USHT increased permeability of hydrophobic molecules (R123 and $[^{14}C]$-antipyrine). The enhanced permeability is reversible and size-dependent as USHT produces a much larger effect on cellular accumulation of $[^{14}C]$-antipyrine (MW 188) than that of R123 (MW 380.8). These results suggest that USHT could affect MDR cells more sensitive than BBMECs. Also, the present results point to the potential use of USHT to increase cellular uptake of P-gp recognized substrates, mainly anti-cancer agents into cancer cells.