• Title/Summary/Keyword: microsphere

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Fabrication of HepG2 Cell Laden Collagen Microspheres using Inkjet Printing (잉크젯 프린팅을 이용한 HepG2 세포 담지 콜라겐 마이크로스피어 제작)

  • Choi, Jin Ho;Kim, Young Ho;Jacot-Descombes, Loic;Brugger, Jurgen;Kim, Gyu Man
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.8
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    • pp.743-747
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    • 2014
  • In this study, drop-on-demand system using piezo-elecrtric inkjet printers was employed for preparation of collagen microspheres, and its application was made to the HepG2 cell-laden microsphere preparation. The collagen microspheres were injected into beaker filled with mineral oil and incubated in a water bath at $37^{\circ}C$ for 45 minutes to induce gelation of the collagen microsphere. The size of collagen microsphere was $100{\mu}m$ in diameter and $80{\mu}m$ in height showing spherical shape. HepG2 cells were encapsulated in the collagen microsphere. The cell-laden microspheres were inspected by the microscopic images. The encapsulation of cells may be beneficial for applications ranging from tissue engineering to cell-based diagnostic assays.

HTGR Nuclear Fuel Microsphere Preparation Using the Modified Sol-Gel Method (변형 Sol-Gel 방법을 이용한 고온가스로 핵연료 미세구입자 제조)

  • Jeong, Kyung-Chai;Kim, Yeon-Ku;Oh, Seung-Chul;Cho, Moon-Sung
    • Journal of the Korean Ceramic Society
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    • v.46 no.6
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    • pp.574-582
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    • 2009
  • $UO_2$ microsphere particles, core material of HTGR(High Temperature Gas Reactor) nuclear fuel, were prepared using by the GSP(Gel Supported Precipitation) method which is a modified-method of the wet sol-gel process. The spherical shape of initial liquid ADU droplets from the vibration nozzle system was continuously kept till the conversion to the final $UO_2$ microsphere. But the size of a final $UO_2$ microsphere was shrunken to about 25% of an initial ADU droplet size. Also, we found that the composition of dried-ADU gel particles was constituted of the very complicated phases, coexisted the U=O, C-H, N-H, N-O, and O-H functional groups by FT-IR. The important factors for obtain the no-crack $UO_2$ microsphere during the thermal treatment processes must perfectly wash out the remained-$NH_4NO_3$ within the ADU gel particle in washing process and the selections of an appropriate heating rate at a suitable gas atmosphere, during the calcining of ADU gel particles, the reducing of $UO_3$ particles, and the sintering of $UO_2$ particles, respectively.

Prediction of the effective thermal conductivity of microsphere insulation

  • Jin, Lingxue;Park, Jiho;Lee, Cheonkyu;Seo, Mansu;Jeong, Sangkwon
    • Progress in Superconductivity and Cryogenics
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    • v.16 no.1
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    • pp.36-41
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    • 2014
  • Since glass microsphere has high crush strength, low density and small particle size, it becomes alternative thermal insulation material for cryogenic systems, such as storage and transportation tank for cryogenic fluids. Although many experiments have been performed to verify the effective thermal conductivity of microsphere, prediction by calculation is still inaccurate due to the complicated geometries, including wide range of powder diameter distribution and different pore sizes. The accurate effective thermal conductivity model for microsphere is discussed in this paper. There are four mechanisms which contribute to the heat transfer of the evacuated powder: gaseous conduction ($k_g$), solid conduction ($k_s$), radiation ($k_r$) and thermal contact ($k_c$). Among these components, $k_g$ and $k_s$ were calculated by Zehner and Schlunder model (1970). Other component values for $k_c$ and $k_r$, which were obtained from experimental data under high vacuum conditions were added. In this research paper, the geometry of microsphere was simplified as a homogeneous solid sphere. The calculation results were compared with previous experimental data by R. Wawryk (1988), H. S. Kim (2010) and the experiment of this paper to show good agreement within error of 46%, 4.6% and 17 % for each result.

The coating of vitamin C on the surface of polymethylmethacrylate microsphere (Polymethylmethacrylate 입자에 표면에 비타민 C의 코팅)

  • Kim, Kyung-Hee;Choi, Seong-Ho
    • Analytical Science and Technology
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    • v.19 no.6
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    • pp.468-472
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    • 2006
  • This paper was described that the preparation of polymetylmethacrylate (PMMA) microsphere and coating of vitamin C onto surface of the prepared PMMA microsphere for application of cosmetic materials. The PMMA microsphere with various sizes can be obtained by change of reaction condition such as reaction temperature and reaction time. The coating of vitamin C on the surface of PMMA microsphere by using cyclodextrin as binder can be achieved to 30 wt-% in water/ethanol mixture. The vitamin C coated with cyclodextrin was stabilized during 56 days at $40^{\circ}C$. The color of the coated Vitamin C was changed from white to dark yellow after 14 days at $40^{\circ}C$. The vitamin C coated with cyclodextrin on the surface of PMMA microsphere can be sufficiently used for cosmetic materials.

Investigation on the Pore Properties of the Microcellular ZrO2 Ceramics Using Hollow Microsphere (중공형 미세구를 이용한 마이크로셀룰라 지르코니아의 가공 특성 고찰)

  • Lee, Eun-Jung;Song, In-Hyuek;Kim, Hai-Doo;Kim, Young-Wook;Bae, Ji-Soo
    • Journal of the Korean Ceramic Society
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    • v.46 no.1
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    • pp.108-115
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    • 2009
  • In this study, a novel-processing route for producing microcellular zirconia ceramics has been developed. The proposed strategy for making the microcellular zirconia ceramics involves hollow microsphere as a pore former which has extremely low density of $0.025\;g/cm^3$. Effects of hollow microsphere content and sintering temperature on microstructure, porosity, pore distribution, and compressive strength were investigated in the processing of microcellular zirconia ceramics. By controlling the content of hollow microsphere, it was possible to make the porous zirconia ceramics with porosities ranging from 45% to 75%. Typical compressive strength value of microcellular zirconia ceramics with ${\sim}65%$ porosity was over 50 MPa. By adjusting the mixing ratio of large and small zirconia powders, it was possible to control the pore structure from close to open pores.

Lightweight Porcelain using GHM(Glass Hollow Microsphere) (유리질 중공체 GHM(Glass Hollow Microsphere)을 활용한 자기의 경량화)

  • Kim, Geun-Hee;Choi, Hyo-Sung;Pee, Jae-Hwan;Cho, Woo-Seok;Kim, Kyeong-Ja
    • Journal of the Korean Ceramic Society
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    • v.48 no.1
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    • pp.74-79
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    • 2011
  • The pore generation technology using GHM (Glass Hollow Microsphere) was studied in order to reduce the weights of porcelain. In this study, we verify the property of modified slurry by adding GHM. The modified slurry was prepared by adding 1.0~2.5 wt%(K1), 1.0~6.0 wt%(K37) of GHM to the slurry for porcelain. The slurry viscosity were stable inside a content range of 1.0~2.5 wt%(K1), 1.0~6.0 wt%(K37). However, the viscosity of modified slurry increased more than 3.0 wt%(K1) and 6.5 wt%(K37). The formed specimen by slip casting was fired at $1229^{\circ}C$, $1254^{\circ}C$. As the amount of GHM content increased, the weight decreased and the addition of 1.0~2.5 wt%(K1), 1.0~6.0 wt%(K37) of GHM resulted in a weight drop of 30%(K1) and 25(K37). However, when the GHM content increased, the strength decreases over 70%. This is caused by the presence of a large volume of surface defects (pores) and defects from the agglomeration of GHM.

Release of Ampicillin-Na from fibrin glue and its adhesive strength as a tissue adhesive (Fibrin glue로부터 Ampicillin-Na의 용출 및 Tissue adhesive로서의 접착력)

  • 유봉규;권익찬
    • Journal of Biomedical Engineering Research
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    • v.16 no.3
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    • pp.367-375
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    • 1995
  • Ampicillin sodium (AMP-Na) was loaded Into fibrin glue (FG) in two different ways and was tried to achieve sustained release from FG. One was loading of AMP-Na in a simple mixing and the other was loading of bovine serum albumin (BSA) microspheres which contained ANP-Na. In case of simple mixing, the release control of AWP-Na from FG was tried by variation of FBNG concentration, but failed. However, the loading of BSA mlcrosphere containing ANP-Na into FG showed sustained re- lease of AMP-Na, especially when microsphere was crosslinked with glutaraldehyde (tO.9 : 33hr). The maximum adhesive strength of FG showed at concentration of FBWG and thrombin, 5.0 % and 25-50 NIHU/ml, respectively. The concentration of Factor Xlll (0-500 U/1g of FBNG) did not affect the adhesive strength of FG. The optimal incubation time was 60 min. The AMP-Na or BSA microsphere which was loaded into FG had no significant effect on the adhesive strength of FG.

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Effect of Pore Formers and Sintering Temperatures on Microstructure and Bending Strength of the Porous Zirconia Ceramics (기공 형성제 조절과 소결 온도의 변화가 다공질 지르코니아 세라믹스의 미세구조 및 강도에 미치는 영향)

  • Lee, Eun-Jung;Song, In-Hyuck;Ha, Jang-Hoon;Hahn, Yoo-Dong;Kim, Yang-Do
    • Journal of Powder Materials
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    • v.18 no.6
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    • pp.502-509
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    • 2011
  • In this study, a novel-processing route for fabricating microcellular zirconia ceramics has been developed. The proposed strategy for making the microcellula zirconia ceramics involved hollow microspheres as pore former. Compared to conventional dense microspheres pore former, well-defined pore structured zirconia ceramics were successfully fabricated. Effects of hollow microsphere content and sintering temperature on microstructure, porosity, pore distribution, and strength were investigated in the processing of microcellular zirconia ceramics.

Fabrication of Porous Alumina Ceramics Using Hollow Microspheres as the Pore-forming Agent

  • Nie, Zhengwei;Lin, Yuyi
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.24 no.4
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    • pp.368-373
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    • 2015
  • Porous alumina ceramics with two different pore sizes were fabricated using hollow microspheres as the pore-forming agent. The relative density, total porosity, and microstructure of the obtained alumina ceramics were studied. It was found that the total porosity of sintered samples with different amounts of hollow microsphere content, from 2.0 to 4.0 wt%, was 69.3-75.6%. The interconnected and spherical cell morphology was obtained with 3.0 wt% hollow microsphere content. The resulting ceramics consist of a hierarchical structure with large-sized cells, and small-sized pores in the cell walls. Moreover, the compressive strength of the sintered samples varied from 8.3-11.5 MPa, corresponding to hollow microsphere contents of 2.0-4.0 wt%.