• Journal of Pharmaceutical Investigation
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• v.32 no.4
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• pp.267-275
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• 2002

A self-microemulsifying drug delivery system (SMEDDS) was developed to increase the dissolution rate, solubility, and ultimately bioavailability of a poorly water soluble drug, lovastatin. SMEDDS was thε mixtures of oils, surfactants, and cosurfactants, which emulsify under conditions of gentle agitation, similar to those which would be encountered in the gastro-intestinal (GI) tract. Various types of self-emulsifying formulations were prepared using four types of oil (Capryol 90, Lauroglycol 90, Labrafil M 1944 CS and Labrafil M 2125), two surfactants (Cremophor EL and Tween 80), and three cosurfactants (Carbitol, PEG 400 and propylene glycol). Thε efficiency of emulsification was studied using a laser diffraction size analyzer to determine particle size distributions of the resultant emulsions. Optimized formulations selected for bioavailability assessment were Carpryol 90 (40%), Cremophor EL (30%) and Carbitol (30%). SMEDDS containing lovastatin (20 mg and 5 mg) were compared to a conventional lovastatin tablet $(Mevacor^{\circledR},\;20\;mg/tab)$ by the oral administration as prefilled hard gelatin capsules to fasted beagle dogs for in vivo study. The arεa under the serum concentration-time curve from time zero to the last measured time in serum, $AUC_{0{\rightarrow}24h}$, was significantly greater in SMEDDS, suggesting that bioavailability increase 130% and 192% by the SMEDDS, respectively. The self-emulsifying formulations of lovastatin afforded the improvement in absolute oral bioavailability relative to previous data of lovastatin tablet formulation. These data indicate the utility of dispersed self-emulsifying formulations for the oral delivery of lovastatin and potentially other poorly absorbed drugs.

• Applied Microscopy
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• v.42 no.2
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• pp.87-93
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• 2012

In this study, fine structures of silica, titanium dioxide, talc and kaolin used in decorative cosmetics and the mixture extracted from BB cream cosmetics were observed by scanning electron microscopy. Kaolin had plate like shape structures of polygon with smooth surface and edge of kaolin had a relatively smooth appearance in comparison with talc. Also, thickness of each layer was estimated to about $0.1{\mu}M$ in the lump formed in stratum of several layers. Talc was observed by lumps shape phase of layering very thin flake. Boundary of thin flake was sharp or angular phase and thickness of flake was approximately 600 nm in diameter. When comparing the thickness of kaolin and talc, we was confirmed that kaolin was thicker than talc. Diameter of titanium dioxide was estimated to 0.2~0.3 ${\mu}M$ and surface of particle was a soft cubic form. Silica was confirmed that variety of size from 200 nm to $15{\mu}M$ of globular shape was measured. From the observation of inorganic pigments, silica was homogeneous dispersed in the BB cream cosmetics and among each other was filled with relatively small size like talc, kaolin, titanium dioxide and iron oxide. In conclusion, we suggest that silica at decorative cosmetics were formed in cosmetic coat at the skin as the minimum thickness.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.115-120
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• 2016

$CeO_2$ is used as a co-catalyst with $TiO_2$ to improve the catalytic activity of $MnO_x$ and characterization of nano-sized powder is identified with de-NOx efficiency. A comparison between $MnO_x-CeO_2/TiO_2$ and single $CeO_2$ was conducted in terms of microstructural analysis to observe the behavior of $CeO_2$ in the ternary catalyst. The $MnO_x-CeO_2/TiO_2$ catalyst was synthesized by sol-gel method and the average particle size of the single $CeO_2$ is about $285{\mu}m$ due to the low thermal stability, whereas the particle size $MnO_x-CeO_2/TiO_2$ is about 130 nm. The strong interaction between Ce and Ti was identified through the EDS mapping by transmission electron microscopy (TEM). The improvement about 20 % of $de-NO_x$ efficiency is observed in the low-temperature ($150^{\circ}C{\sim}250^{\circ}C$) and vigorous oxygen exchange by well-dispersed $CeO_2$ is the reason of catalytic activity improvement.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.404-409
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• 2017

Natural polymer chitosan has been widely applied to medical fields due to its biochemical activities such as anticancer, antibacterial and lowering cholesterol in addition to biocompatibility and biodegradability. Currently, researches are being actively conducted to develop various drug-encapsulated chitosan nanoparticles for curing different diseases by applying chitosan to a drug delivery system. The free amine ($-NH_2$) group present in chitosan can bind to various hydrophobic groups by physical and chemical modification and the chitosan with hydrophobic groups can form shell-core nanoparticles by self-assembly when dispersed in water. In addition, an insoluble drug can increase the solubility against water when it was encapsulated in the core of chitosan nanoparticles. Also, the therapy effect can be maximized by minimizing side effects of drugs such as proteins, anticancer drugs and vaccines when they were encapsulated in the core of chitosan nanoparticles. Moreover, it is possible to control the particle size and release rate according to the hydrophobic group introduced to chitosan, so that it can be applied to a wide range of medical fields. The purpose of this review is to discuss the preparation and property of chitosan nanoparticles modified with various hydrophobic groups, and the application to drug delivery systems according to their property.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.174-181
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• 2007

In this study, $SiO_2/poly(ethylene-co-vinyl$ alcohol)(EVOH) hybrid coating materials with gas barrier property could be produced using sol-gel method. The biaxially oriented polypropylene (BOPP) substrate with surface pretreatment was coated with the prepared hybrid sols containing various inorganic silicate component by a spin coating method. Crystallization behavior of the hybrids was investigated in terms of analysis of X-ray diffraction and cooling thermogram from DSC experiment. From the morphological observation of the $SiO_2/EVOH$ hybrid gel, it was confirmed that there existed an optimum content of inorganic silicate precursor, Tetraethylorthosilicate (TEOS), to produce hybrid materials with dense microstructure, exhibiting uniformly dispersed silica particles with average size below 100 nm. When TEOS was added at below or above the optimum content, particle clusters with large domain were observed, resulting in phase separation. This morphological result was found to be in good agreement with that of oxygen permeability of the hybrid coated films. In the case of film coated with hybrid prepared from addition of 0.01 - 0.02mol of TEOS, a remarkable improvement in barrier property could be obtained, however, with the addition of TEOS more than 0.04 mol, the barrier property was dramatically reduced because of phase separation and micro-crack formation on the film surface.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.55-59
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• 2004

We fabricates the $TiO_2$ thin film from anatase phase $TiO_2$ powder having good photocatalytic property using aerosol deposition method at room temperature. Aerosol deposition method, which sprays an aerosol powder with ultrasonic velocity and deposits a thin film on substrate at low temperature, has the advantages of low thermal stress and low cost. To fabricate the $TiO_2$ thin film, the aerosol bath pressure and chamber pressure were 500 torr and 0.4 torr, respectively. The difference of aerosol bath pressure and chamber pressure accelerated the $TiO_2$ nano powder to ultrasonic velocity through the nozzle of $0.4 mm{\times}10 mm$ and $TiO_2$ thin film was finally formed. SS mesh with diameter of 50 mm was used as a substrate to apply the $TiO_2$ thin film to water quality purification. The raw powder was dehydrated for the good dispersion of $TiO_2$ powder. To suppress the formation of second particle, the powder was dispersed for 90 min in alcohol bath by ultrasonic treatment and desiccated. The grain size of $1 {\mu}m$ was observed in $TiO_2$ thin film deposited on SUS mesh by scanning electron microscopy (SEM). The anatase phase of $TiO_2$ thin film was also observed by X-ray diffraction (XRD) and the anatase phase of raw powder was nicely maintained after aerosol deposition. The results are applicable to water treatment filter having photocatalytic reaction.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.918-924
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• 1998

This study has been carried out to investigate the effect of reaction milling time on the synthesis of Ti- TiC p powder synthesised from the elemental titanium and activated carbon by reaction milling(RM), and the effect of vacu­u urn hot pressing temperature and TiC volume fraction on microstructural and mechanical properties of Ti- TiC com­p posite $\infty$ns이idated by vacuum hot pressing(VHP).T The elemental powders of titanium and activated carbon can be converted into Ti- TiC composite powders by reac­t tion milling for about 300hours, and were the average grain size of the as- milled powders has been measured to be a about $5\mu\textrm{m}$. The relative density of Ti- TiC VHPed above $1000^{\circ}C$ during Ihr is about 98% and the mechanical properties o of In- situ Ti- TiC composites are improved by TiC particle dispersed uniformly on titanium matrix. In order to investi­g gate thermal stability of Ti- TiC composite, after annealing at $600^{\circ}C$ for 80hrs micro- Vickers hardness have been per­f formed, and the values have been shown little changed as compared with those before annealing. The compact has b been tested on high temperature compressive test at $700^{\circ}C$ and has showed a high temperature compressive strength of 330MPa in a Ti- 20vol% TiC.

• Resources Recycling
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• v.18 no.6
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• pp.30-37
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• 2009

Silica sol was prepared from the mixture of sodium silicate solution and oxidized silicate solution in which sodium had been removed by sol-gel process. The properties of sodium silicate solution and silicate solution thus prepared were characterized by yellow silicomolydate method. Moreover, the formation and growth of silica sol from sodium silicate solution was investigated. Sodium silicate solution with 2% of $SiO_2$ contains 95% of reactive silicate, and 50% of reactive silicate participates sol-gel reaction. From the results of FT-IR analysis, it was found that the intensity of silanol bond decreased and the intensity of siloxane bond increased with increasing reaction temperature. Zeta potential of silica sol prepared at each condition was -40~-60 mV and it could be known that silica sol in this study was well dispersed. The silica sol with 5~10 nm size could be prepared by heating the mixed solution of sodium silicate and silicate solution. And the silica sol grew into about 20 nm as silicate solution was added to silica sol solution.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.523-528
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• 2023

The applicability as a material to improve solar cell performance was reviewed by synthesizing a phosphor that emits red wavelengths by a liquid synthesis method using a metal salt aqueous solution and a polymer medium as a starting material. An aqueous solution was prepared using nitrate of metals such as Ca, Zn, Al, and Eu, and a precursor impregnated with starch, a natural polymer, was sintered to synthesize CaZnAlO:Eu phosphor powder. The surface structure and composition analysis of the synthesized CaZnAlO:Eu phosphor powder were analyzed by scanning electron microscope(SEM) and energy-dispersed X-ray spectroscopy(EDS). The crystal structure of CaZnAlO:Eu phosphor particles was analyzed by an X-ray diffraction analyzer (XRD). As a result of measuring the photoluminescence(PL) characteristics of the phosphor, it was confirmed that a red phosphor with a light emitting wavelength of 650-780nm was successfully synthesized. According to SEM and EDS analysis, the synthesized Ca₁₄Zn₆Al_9.93O₃₅:Eu³⁺_0.07 phosphor powder has a uniform particle size, and Eu ions used as an activator are present. The synthesized CZA:Eu³⁺ phosphor can be used as a material that can increase the light absorption efficiency of the solar cell by converting ultraviolet or visible light down conversion into a wavelength in the near-infrared region.

• Journal of the Mineralogical Society of Korea
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• v.22 no.3
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• pp.249-259
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• 2009

The objective of this research was to find out the physical properties, such as dispersion and coagulation, of soil minerals depending on the types and concentrations of the cations in aqueous solution. Hwangto samples were obtained from 90 to 130 cm from surface at Jangdong-ri, Donggang-Myon, Naju, Chonnam Province. The clay fraction (< $2\;{\mu}m$) was separated by sedimentation method from the bulk soils. Both Hwangto and clay fractions, and the same samples after removal of amorphous and crystalline iron oxides were used in this experiment. The effect of 4 cations ($Na^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$) and their concentrations on settling speed and basal spacing of the minerals were observed to examine the physical properties of the soil and clay minerals. Hwangto mainly consisted of quartz, and the clay fractions consisted of kaolinite, illite, and vermiculite. The bulk soils contained 16.3 mg/kg of amorphous iron oxides and 436 mg/kg of crystalline iron oxides. Clay fractions were dispersed better than bulk soils due to their smaller particle size than that of the bulk samples in the aqueous solution. The bulk and clay samples were dispersed better when iron oxides were removed because of coating of minerals by the iron oxides. Clay minerals were settled faster as the charge and the concentration of cations added increased. The d-spacing of kaolinite and illite did not change when 4 types of cations were added. The d-spacing of vermiculite showed $14.04\;{\AA}$ when divalent cations were added while that of vermiculite showed $13.9\;{\AA}$ when monovalent cations were added. It may be attributed to the hydration radii of cations. This study indicated that both coating of iron oxides on minerals and types and concentrations of cations affect dispersion of minerals in solution and d-spacing of expanding clay minerals such as vermiculite.