• 제목/요약/키워드: microsphere

검색결과 223건 처리시간 0.022초

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

  • 최진호;김영호;로익 자코 데콩브;유르겐 부르거;김규만
    • 한국정밀공학회지
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    • 제31권8호
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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.

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

  • 정경채;김연구;오승철;조문성
    • 한국세라믹학회지
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    • 제46권6호
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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
    • 한국초전도ㆍ저온공학회논문지
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    • 제16권1호
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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.

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

  • 김경희;최성호
    • 분석과학
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    • 제19권6호
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    • pp.468-472
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    • 2006
  • 기능성 화장품 원료로서 관심을 갖는 비타민 C(L-ascobic acid)는 피부에 대한 안전성, 항산화성으로 인해 노화방지 및 미백, 잔주름개선 등의 효능을 갖지만 화학적으로 쉽게 산화된다. 따라서 본 연구에서는 비타민 C의 안정성에 대한 단점을 보완하기 위하여, 에멀젼 중합법으로 다양한 마이크론 크기의 Polymethylmethacrylate(PMMA)입자를 제조하고, 제조된 PMMA의 입자 표면에 코팅용액(물과 에탄올 혼합용매에 cyclodextrin과 비타민 C를 녹인 용액)을 이용하여 비타민 C를 코팅처리 하였다. 코팅처리 후, 실온 및 $40^{\circ}C$에서 시간에 따른 비타민 C의 함량을 조사한 결과, 56일이 경과후에도 비타민 C가 86.4%가 잔존함을 확인 할 수 있었다.

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

  • 이은정;송인혁;김해두;김영욱;배지수
    • 한국세라믹학회지
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    • 제46권1호
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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.

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

  • 김근희;최효성;피재환;조우석;김경자
    • 한국세라믹학회지
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    • 제48권1호
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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.

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

  • 유봉규;권익찬
    • 대한의용생체공학회:의공학회지
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    • 제16권3호
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    • pp.367-375
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    • 1995
  • 광범위 항생물질인 Ampicillin sodium(AMP-Na)을 두가지 방법 즉, 단순섞임과 bovine serum albumin(BSA)으로 microsphere화한 후 loading 하는 방법으로 fibrin glue(FG)를 제조하였고 이 FG로부터 AMP-Na의 서방성 시험을 시도하였다. 단순섞임의 경우 fibrinogen(FBNG)의 농도를 조적함으로서 FG로부터 AMP-Na의 지속적 방출을 달성할 수 있었으며 특히 이 microsphere를 glutaraldehyde로 가교화시킴으로서 용출속도를 더욱 늦출 수 있었다.(tO.9 : 33hr). FG의 rat perironeum에 대한 접착력은 FBNG과 thrombin의 농도가 각각 5.0%, 25~50 NIHU/ml에서 최대로 나타났다. Factor XIII의 농도는 0~500 U/1g of FBNG의 범위내에서 접착력에 거의 영향을 미치지 않았으며 incubation time은 60분일 때 최대로 나타났다. FG에 AMP-Na 및 BSA micorsphere를 loading하여도 접착력에는 큰 영향을 미치지 않았다.

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

  • 이은정;송인혁;하장훈;한유동;김양도
    • 한국분말재료학회지
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    • 제18권6호
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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
    • 한국생산제조학회지
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    • 제24권4호
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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%.