• Journal of Pharmaceutical Investigation
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• 제38권1호
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• pp.39-43
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• 2008

Cyclosporin A (CyA), a potent immunosuppressive drug used in allogeneic transplants and autoimmune disease, is a typical water-insoluble drug. Recently, nanoparticle carriers were investigated to improve the intestinal absorption of drugs. In this study, CyA-loaded nanostructured lipid carriers (NLCs) were prepared from a hot o/w emulsion using the high pressure homogenization method. The NLCs were consisted of cationic lipids, solid lipids, liquid lipids (oils), surfactant and stabilizer. Encapsulation efficiency of CyA in NLCs was approximately 71%. The average particle size and zeta potential of NLCs were below 250 nm and above +40 mV, respectively. The morphology of NLCs was confirmed by transmission electron microscopy (TEM) analysis. Compared to the CyA powder, higher in vitro release of CyA from NLCs was observed after burst release within 30 min. Thus, CyA-loaded NLCs could be applied not only for parenteral route but also for gastrointestinal administration, which needs further investigation.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.183-187
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• 2010

Core-Shell polymers of silicone dioxide-styrene system were prepared by sequential emulsion polymerization. In inorganic/organic Core-Shell composite particle polymerization, silicone dioxide adsorbed by surfactant sodium dioctyl sulfosuccinate (EU-DO133L) was prepared initially and then core silicone dioxide was encapsulated emulsion by sequential emulsion polymerization using styrene at the addition of potassium persulfate (KPS) as an initiator. We found that $SiO_2$ core shell of $SiO_2$/styrene structure was formed when polymerization of styrene was conducted on the surface of $SiO_2$ particles, and the concentration sodium dioctyl sulfosuccinate (EU-DO133L) was 0.5~2.0g. The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of latex by scanning electron microscope(SEM).

• 분석과학
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• 제27권6호
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• pp.314-320
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• 2014

$La_{2-x}(MoO_4)_3:Er^{3+}/Yb^{3+}$ particles with doping concentrations of $Er^{3+}$ and $Yb^{3+}$ ($x=Er^{3+}+Yb^{3+}$, $Er^{3+}$=0.05, 0.1, 0.2 and $Yb^{3+}$ = 0.2, 0.45) were successfully prepared by the microwave-modified sol-gel method, and the upconversion photoluminescence properties were investigated. Well-crystallized particles, formed after heat-treatment at $900^{\circ}C$ for 16 h, showed a fine and homogeneous morphology with particle sizes of $2-5{\mu}m$. Under excitation at 980 nm, $La_{1.7}(MoO_4)_3:Er_{0.1}Yb_{0.2}$ and $La_{1.5}(MoO_4)_3:Er_{0.05}Yb_{0.45}$ particles exhibited a strong 525 nm emission band, a weak 550 nm emission band in the green region, and a very weak 655 nm emission band in the red region. The Raman spectra of the doped particles indicated the presence of strong peaks at higher frequencies of 752, 846, 922, 1358 and $1435cm^{-1}$ and lower frequency of $314cm^{-1}$ induced by the disorder of the $[MoO_4]^{2-}$ groups with the incorporation of the $Er^{3+}$ and $Yb^{3+}$ elements into the crystal lattice or by a new phase formation.

• 공업화학
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• 제20권5호
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• pp.565-569
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• 2009

녹색과 청색의 나노 형광체 합성에 있어서 입자 형상 및 입자 크기의 변화를 알아보기 위해 액상법으로 진행하였으며, 이를 바탕으로 최종적으로 녹색 형광체의 경우 약 80 nm를, 그리고 청색 형광체의 경우 약 60 nm급의 나노 형광체 분말 합성이 가능하였다. 합성된 두 가지의 $Zn_2SiO_4$ : Mn 녹색 형광체와 BAM : Eu의 청색 나노 형광체 분말의 특성 평가를 비교하였으며, 그 결과 PL 특성면에서 녹색 형광체인 $Zn_2SiO_4$ : Mn이 BAM : Eu의 청색 형광체 대비 높은 형광성을 보여주었다.

• 한국분말재료학회지
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• 제24권2호
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• pp.141-146
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• 2017

$Bi_2Te_3$ powders are recovered by wet chemical reduction for waste n-type thermoelectric chips, and the recovered particles with different morphologies are prepared using various surfactants such as cetyltrimethylammonium bromide (CTAB), sodium dodecylbenzenesulfonate (SDBS), and ethylenediaminetetraacetic acid (EDTA). When citric acid is added as the surfactant, the shape of the aggregated particles shows no distinctive features. On the other hand, rod-shaped particles are formed in the sample with CTAB, and sheet-like particles are synthesized with the addition of SDBS. Further, particles with a tripod shape are observed when EDTA is added as the surfactant. The growth mechanism of the particle shapes depending on the surfactant is investigated, with a focus on the nucleation and growth phenomena. These results help to elucidate the intrinsic formation mechanism of the rod, plate, and tripod structures of the $Bi_2Te_3$ recovered by the wet reduction process.

• 한국세라믹학회지
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• 제46권2호
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• pp.170-174
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• 2009

$BaTiO_3$ powder was synthesized by the solid-state reaction of fine $BaTiO_3$ and $TiO_2$ raw materials. Fine grinding media of 50 and 300 microns were used for obtaining fine particulate mixture of $BaTiO_3$ and $TiO_2$ with high homogeneity. Effect of the size of grinding media on the synthesis mechanism of $BaTiO_3$ was discussed on the basis of the particulate morphology and thermogravimetry data for the mixture powders. By using the finer grinding media, $BaTiO_3$ was formed at the lower temperature and the particle size with the relatively narrower distribution could be obtained. $BaTiO_3$ powder with the average size of 100 nm was synthesized by the solid reaction in vacuum atmosphere.

• 폴리머
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• 제36권5호
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• pp.662-667
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• 2012

평판 디스플레이에 사용되는 PET 필름의 광학적 특성을 알아보기 위하여 필름 표면 굴절률, 필름 표면조도 및 필름 내부입자가 광투과율에 미치는 영향을 알아 보았다. 필름표면에 굴절률이 낮은 코팅층을 형성함에 따라 필름의 광투과율이 향상되었고, 최대의 광투과율을 가지는 코팅두께가 있음을 확인하였다. 표면 거칠기의 영향에 대해서는 표면조도를 나타내는 Ra를 입사 파장의 1/4 이하로 조절한 경우 광손실이 발생되지 않았다. 필름 내 무기입자는 입사된 광의 흡수 및 산란을 발생시켜 광손실을 증가시켰다.

• 한국재료학회지
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• 제26권7호
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• pp.363-369
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• 2016

$NaCaLa_{1-x}(MoO_4)_3:Ho^{3+}/Yb^{3+}$ ternary molybdates with proper doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ (x = $Ho^{3+}+Yb^{3+}$, $Ho^{3+}$ = 0.05 and $Yb^{3+}$ = 0.35, 0.40, 0.45 and 0.50) were successfully synthesized by microwave sol-gel method. Well-crystallized particles formed after heat-treatment at $900^{\circ}C$ for 16 h showed a fine and homogeneous morphology with particle sizes of $3-5{\mu}m$. Under excitation at 980 nm, the UC intensities of the doped samples exhibited strong yellow emissions based on the combination of strong emission bands at 520-nm and 630-nm emission bands in the green and red spectral regions, respectively. The optimal $Yb^{3+}:Ho{3+}$ ratios were obtained at 9:1 and 10:1, as indicated by the composition-dependent quenching effect of the $Ho^{3+}$ ions. The pump power dependence of the upconversion emission intensity and the Commission Internationale de L'Eclairage chromaticity coordinates of the phosphors were evaluated in detail.

• 한국재료학회지
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• 제27권1호
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• pp.8-11
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• 2017

Binary Ti-Al alloys containing 50 to 60 atomic percent aluminum are rapidly solidified by hammer anvil method under an argon atmosphere. Constituent phases in each alloy are identified by X-ray diffractometry and microstructures of the alloys are investigated using a transmission electron microscope. In alloys with aluminum content between 50 and 54 percent, a second phase exists besides TiAl(${\gamma}$); this second phase is identified as $Ti_3Al$(${\alpha}2$). The ${\alpha}2$ phase is observed in two types of morphology. One is as fine lamellar alternating with ${\gamma}$ and the other is as a particle. It is concluded that the existence of a metastable phase with the morphologies stated above should arise from a higher quenching rate attained by the hammer anvil method as compared to the conventional roll or splat-quench method. Implications of the above observation are discussed with respect to the phase relations in the Ti-Al binary system; these implications are still controversial in many respects.

• 한국축산식품학회지
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• 제32권2호
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• pp.155-161
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• 2012

This study was carried out to investigate the encapsulation of lactic acid in starch matrix for the application into emulsified sausages. For the encapsulation of lactic acid in starch, the extrusion method was applied, by the different extrusion pressure level. The particle size and morphology of lactic acid containing starch granules and the rate of release of lactic acid from those granules were determined by using Mastersizer$^{(R)}$, a scanning electron microscopy, and electrical conductivity. The size varied slightly depending upon the extruder pressure and influenced entrapment efficiency. Lactic acid was released more slowly, when the extruder had fewer holes, which meant higher extrusion pressure, than when the extruder had more holes. Extruder pressure is therefore critical for producing finer granules that can retain lactic acid longer, during the processing of meat products.