• Title/Summary/Keyword: preparation process

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TEM Specimen Preparation Method of Gibbsite Powder for Quantitative Structure Analysis (정량 구조 분석을 위한 Gibbsite 분말의 TEM 시편 준비법)

  • Kim, Young-Min;Jeung, Jong-Man;Lee, Su-Jeong;Kim, Youn-Joong
    • Applied Microscopy
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    • v.32 no.4
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    • pp.311-317
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    • 2002

  • There is great requirement on the TEM specimen preparation method with particle size selectivity as a prerequisite for the quantitative structure analysis on the materials such as gibbsite powder, which generally forms a large agglomerate and shows a variation of transition process depending on their sizes. In this experiment, we made an attempt to give a methodology for the TEM specimen preparation of powder with the size selectivity. After mixing 1 wt% gibbsite powder with ethanol solvent, gibbsite suspension was prepared by application of ball-milling and ultrasonification with addition of 0.25 vol% dispersion agent, Darvan C, which was diluted into distilled water by the ratio 1:19. Appling the static sedimentation method to gibbsite suspension after estimation of the sedimentation time by the measurement of accumulative concentration variation, we acquired TEM specimens with well-dispersed and size selected gibbsite particles in nm scale. Overall picture of each sample was taken by SEM and morphology of each dispersed particle was imaged by TEM. Raw and processed gibbsite powders were also examined by XRD to investigate whether they were suffered from phase change during the process or not.

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Sample Preparation of Ductile Heterogeneity Materials by Ultramicrotomy (연성 이종 재료 시료의 상온 절편 제작법)

  • Chae, Hee-Su;Kweon, Hee-Seok;Je, A-Reum;Lee, Seok-Hoon;Kim, Jin-Gyu
    • Applied Microscopy
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    • v.42 no.1
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    • pp.49-52
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    • 2012

  • For TEM study of biological samples or polymers that are contained in organic structure, it is often required that the sample is prepared by using ultramicrotome and stained with proper agents to increase the contrast of organic structure. In this study, we investigated an efficient TEM sample preparation method for ductile heterogeneity material by using ultramicrotomy. Cryo-ultramicrotomy is a suitable method that is capable of rendering sample hardness for various ductile materials. However, it has several factors to consider, such as experimental cost, working time and finding the optimal staining conditions. To satisfy these considerations, we prepared TEM sample by using ultramicrotome without cryofunction, and secured the sample hardness by applying the staining process prior to ultrathin sectioning. The cross-linked polyethylene structure in the sample was stained with the 2% $RuO_4$ solution in a sealed test tube for 24 hours at $4^{\circ}C$. After the sample staining, ultrathin sections of sample were prepared using ultramicrotome. As a result, it was revealed that the difficulties associated with staining of ultrathin sections prepared by low-temperature conditions were improved. In addition, appropriate staining depth of sample could be selected for sectioning process. The quality of TEM sample obtained by using this method was better than that of cryo-ultramicroscopy. Finally, it is expected that our method could be effectively applied in TEM sample preparation for a variety of nano-bio convergence materials.

  • https://doi.org/10.9729/AM.2012.42.1.049 인용 PDF KSCI

Microbiological Hazard Analysis and Preparation of Standard Recipe for Bellflower Roots with Seasonings Served in a University Foodservice Operation (대학급식에서 제공되는 통도라지 무침의 미생물학적 위해분석과 표준레시피 작성)

  • Ryu, Gyeong;Chae, Hyeon-Suk;Kim, Un-Ju
    • Journal of the Korean Dietetic Association
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    • v.12 no.2
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    • pp.157-171
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    • 2006

  • This study was intended to suggest HACCP-based standard recipe for bellflower roots, classified as no thermal cooking process, served in a university foodservice operation. The time-temperature and microbial contamination level in each cooking step were analyzed. The temperatures of bellflower root, peeled garlic and green onion at receiving were at 13.8$\pm$2.8, 12.6$\pm$2.9 and 13.7$\pm$$0.8^\circC$ respectively, which were above the temperature limit. The time consumed for pre-preparation was up to 90 min at room temperature having high microbial growth potential. The levels of total plate counts (TPC) of bellflower root and garlic were over the limit of $10^6$ CFU/g as were the numbers of coliforms in bellflower roots. There were no microbial reductions in pre-preparation and cooking, which resulted in over $10^5$- $10^6$ CFU/g of TPC at service step. Two CCPs identified were washing/sanitation at pre-preparation and service steps. The control measures were washing/sanitation and temperature control. It was verified that CCPs for no cooking process developed in preceding studies were applicable for the microbiological food safety of this menu item. The HACCP-based standard recipe was developed to produce a quantity for 100 servings by observing the critical limits established for CCPs. These results suggest that the selection of proper provider is imperative to control the microbial contamination of raw materials at purchasing step. Also, the sanitary education program should be developed for the employees to understand and comply the HACCP plan and standard recipe.

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