• Journal of Pharmaceutical Investigation
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• v.28 no.3
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• pp.141-149
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• 1998

In order to reduce systemic side effects following administration, flurbiprofen was formulated as O/W microemulsion consisting of the surfactant, oil phase and aqueous phase. Particle size distribution, apparent viscosity, solubility and skin permeation of flurbiprofen in various vehicles and microemulsion were evaluated. The domain of O/W microemulsion s phase diagram had difference between oil types and the area of O/W microemulsion was wide distributed by adding to PG and cosurfactant than that of water alone. As increasing 10, 15 and 20% of Brij 97 content and 1, 2.5, 5% of oil content, the solubility of flurbiprofen in O/W microemulsions and various vehicles was $400{\sim}1,000$ and $10{\sim}500$ times higher than that of control. Also, apparent viscosity of soybean oil microemulsions was higher than that of IPM microemulsions and that of vehicle were increased as increasing vehicle content. Since skin permeation of flurbiprofen decreased as increasing viscosity, in each vehicle, it was not affected 2% ${\beta}-CD$ and decreased as increasing PG content and to 2, 5 and 10% of $HP-{\beta}-CD$. In O/W microemulsion, 5% soybean oil. 20% Brij 97 and 75% water(A-1) with high viscosity showed low skin penetration.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.601-601
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• 2013

Superhydrophobic W18O49 nanowire (NW) arrays were synthesizedusing a thermal evaporation and surface chemistry modification methods by self-assembled monolayer (SAM). As-prepared non-wetting W18O49 NWs surface shows water contact angle of $163.2^{\circ}$ and has reliable stability in underwater conditions. Hence the superhydrophobic W18O49 NWs surface exhibits silvery surface by total reflection of water layer and air interlayer. The stability analysus of underwater superhydrophobicity of W18O49 NWs arrays was conducted by changing hydrostatic pressure and surface energy of W18O49 NWs arrays. The stability of superhydrophobicity in underwater conditions decreased exponentially as hydrostatic pressure applied to the substrates increased3. In addition, as surface energy decreased, the underwater stability of superhydrophobic surface increased sharply. Specifically, sueprhydrophobic stability increased exponentially as surface energy of W18O49 NWs arrays was decreased. Based on these results, the models for explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. The combination of fugacity and Laplace pressure explained this exponential decay of stability according to hydrostatic pressure and surface energy. This study on fabrication and modeling of underwater stability of superhydrophobic W18O49 NW arrays will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications even submerged underwater.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.1
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• pp.1-16
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• 2010

The preparation and properties of emulsions stabilized by the adsorption of solid particles at the oil-water interface are reviewed. Comparison is made with the behaviour of surfactant-stabilized emulsions. Many of the properties of Pickering emulsions are attributed to the large free energy of adsorption for particles. The main differences is due to the irreversible adsorption of particles to the interface. Phase inversion from w/o (water-in-oil) to o/w (oil-in-water) can be brought by increasing the volume fraction of water. Hydrophilic particles tend to form o/w emulsion whereas hydrophobic particles form w/o emulsion. The contact angle at the oil-water interface is main parameter to decide the emulsion type. The aspects of stability of Pickering emulsions are in contrast to general emulsions in some points. The possibility using Pickering emulsions for cosmetics is also proposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.755-758
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• 2000

YMnO$_3$films have been deposited with different Rf powers of 60W, 80W, 100W, and 120W. The structural properties of YMnO$_3$films on Si(100) were analysed by XRD(X-ray diffraction). The c-axis oriented peaks of YMnO$_3$were observed deposited in YMnO$_3$/Si(100) structure of RF power at 87$0^{\circ}C$ in oxygen ambient, and the peaks were enlarged by increasing The RF powers. The dielectric constant of the film deposited at 100W and 120W of RF power were about 19, 20 respectively.

• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.705-711
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• 1989

The glass-ceramics was prepared with the scoria(CaO-MgO-Al2O3-SiO2 system) of the locally occurring volcanic ejecta containing 10-13w/o of (FeO＋Fe2O3) by melting at 140$0^{\circ}C$ for 4 hours and thermally treated for nucleation and crystallization. The sucrose was added to the scoria to adjust the Fe2+/Fe3+ ratio during the melting process. The addition of 1-2w/o of sucrose showed the glass-ceramics body with the finest particle developed and dispersed over the entire range. It is concluded that the impurity content of iron oxide and titanium oxide play the most-influencial effect on the crystallization. When 1-2w/o of sucrose was added to the scoria, the value of Fe2+/Fe3+ ratio was 0.93-1.32 and showed the best result of crystallization. The nucleation temperature and time were calculated by the measurements of exothermic peak temperatures of DTA for quenched and thermally treated glasses. The nucleation temperature of scoria glass without the addition of sucrose was estimated as 75$0^{\circ}C$, but the addition of sucrose by 2w/o showed the nucleation temperature 6$25^{\circ}C$. The nucleation time was calculated with the same DTA curves. The nucleation times estimated were about 150min. for both of glasses without and with sucrose added. Finally, the activation energies for crystallization were calculated with the DTA data. The calculated activation energies were 143 Kcal/mole for the glass without addition of sucrose and 90Kcal/mole, 87Kcal/mole, 85Kcal/mole and 71Kcal/mole for the glasses of 1w/o, 2w/o, 3w/o and 4w/o addition respectively.

• Journal of Pharmaceutical Investigation
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• v.39 no.4
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• pp.249-255
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• 2009

The main object of this study was to prepare of w/o emulsion including glyceryl monooleate(GMO) and to evaluate its stability by using the recently developed $Turbiscan^{(R)}LAB$. GMO is the polar oily surfactant with the low HLB value, and it forms the gel phase of cubic structures after dissolves in aqueous media. Phosphate buffer solution (PBS) of pH 7.4 was prepared as the water phase and Marcol 52(mineral oil) was used as the oil phase in this study. GMO was used as the surfactant of W/O emulsion. W/O emulsion using GMO alone as a surfactant was very unstable. But the emulsion using both GMO and poloxamer 407 was more stable. The stability of W/O emulsions was evaluated after centrifuging the emulsions. But it was difficult with naked eye because an opaque and concentrated system like W/O emulsion was very turbid. So $Turbiscan^{(R)}LAB$ was used to detect the destabilization phenomena in non-diluted emulsion. As a result, the W/O emulsion using the proper amounts of GMO and poloxamer 407 was more stable among them using GMO of various amounts. But it seems that the other element for the stability of W/O emulsion including GMO was required. Furthermore, the $Turbiscan^{(R)}LAB$ was a very efficient analyzer for evaluating the physical stability of emulsion.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.22 no.2
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• pp.132-140
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• 1996

The effect of a novel delivery system, water in oil emulsion containing chitosan hydrogel as a inner phase (W/O-C) was evaluated, and the relationships between the skin permeation, the skin primary irritation and the skin turnover rate of AHAs were discussed. We selected glycolic acid (GA), lactic acid (LA), malic acid (MA), and tartaric acid (TA) as model AHAs. The steady state fluxes of 4 AHAs across the excised hairless mouse skin increased as the molecular weights of the AHAs decreased. (GA>LA>MA>TA). The skin turnover times were shortened in all AHAs, compared with control. The skin permeation and the skin primary irritation of the LA decreased and the skin turnover time increased, as the pH increased. The maximum therapeutic index was obtained with pH 3.8, 0.5 M LA. It was suggested that the skin permeability of LA might be a main factor for prediction of the skin irritation and the skin turnover time. On the other hand, the W/O-C containing pH 3.8, 0.5 M LA indicated a good sustained release property of LA, compared with water in oil emulsion without chitosan hydrogel (W/O) or oil in water emulsion (O/W). The skin permeability and the skin irritation of AHAs from the W/O-C edcreased, compared with W/O or O/W, however the skin turnover time showed almost the same value as W/O or O/W. In conclusion, we suggest that the control of the skin permeation of AHAs would be an important tool for reducing the skin irritation and for maintaining the positive effect of AHAs, and the W/O-C system could be a potential candidate for future cosmetological application of AHAs.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.2
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• pp.127-133
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• 2016

In this study, water-in-oil (W/O) nanoemulsions of water/Span 80-Nikkol BL 25/oil system were prepared by the PIC method at elevated temperature. This method allows the formation of finely dispersed W/O nanoemulsions with low viscosity in this system. However, macroemulsions rather than nanoemulsions were prepared by PIC method at room temperature. As a result of the significant change of interfacial tension with temperature, the emulsion droplet size decreases from $2{\mu}m$ to 100 nm with the increase in temperature from $30^{\circ}C$ to $80^{\circ}C$. The droplet size of nanoemulsions prepared at $80^{\circ}C$ was in the range of 50 ~ 200 nm and the internal phase content could reach as high as 15 wt%. The most stable nanoemulsion was formed in the vicinity of 7.0 of optimum HLB of the emulsifier mixture. The obtained nanoemulsions were stable without obvious change in droplet size in one month. This study provides valuable information for optimizing the formation of W/O nanoemulsions with low viscosity. These results suggest that W/O nanoemulsions of low viscosity could be useful for cosmetics with soft feeling.

• Journal of the Korean Ceramic Society
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• v.22 no.2
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• pp.17-24
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• 1985

In the composition of $Pb(Mg_{0.15} W_{0.15})Ti_{0.35}-Zr_{0.35}O_3$ the effect of particle size on PbO vaporization were measured, . The initial step of discontinuous vaporization of unreated PbO during the calcining process was depended on the particle size. All additives $La_2O_3Nb_2O_5$ and $Al_2O_3$ inhibited the grain growth of the composition $Pb(Mg_{0.15} W_{0.15})Ti_{0.35}-Zr_{0.35}O_3$ +2wt% excess PbO. The dielectric and piezoelectric properties of the composition $Pb(Mg_{0.15} W_{0.15})Ti_{0.35}-Zr_{0.35}O_3$ were improved by the addition of 2wt% excess PbO and proper additive. The electromechanical planar coupling factor of 0.65 and mechnical quality factor of 390 could be obtained by adding 5wt% $Nb_2O_5$ to the composition 2wt% excess PbO+$Pb(Mg_{0.15} W_{0.15})Ti_{0.35}-Zr_{0.35}O_3$.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.121-122
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• 2008

The films of the vanadium tungsten oxide, $V_{1.85}W_{0.15}O_5$, were grown on Pt/Ti/$SiO_2$/Si substrate by RF sputtering method. It was found that film crystallinity, dielectric properties, and TCR properties were strongly dependent upon the thin film thickness. As increasing of $V_{1.85}W_{0.15}O_5$ thickness, the grain size, morphology, and crystallinity increased. The dielectric constants of $V_{1.85}W_{0.15}O_5$ thin films deposited at 150nm were 71.11, with a dielectric loss of 0.015, respectively. Also, The $V_{1.85}W_{0.15}O_5$ thin films showed good TCR values of -3.45%/K.