• 제목/요약/키워드: microscopic structure

검색결과 523건 처리시간 0.022초

Application of the Band-pass Filtering for Improving 3D Tomogram of Micron-thick Sections of Biological Specimens (생물시료의 3D Tomogram 정밀도 개선을 위한 Band-pass Filtering 활용)

  • Ryu, Keun-Yong;Kim, Mi-Jeong;Choi, Ki-Joo;Je, A-Reum;Kim, Soo-Jin;Lee, Chul-hyun;Jung, Hyun-Suk;Park, Jong-Won;Kweon, Hee-Seok
    • Applied Microscopy
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    • 제42권2호
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    • pp.105-109
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    • 2012
  • Electron tomography (ET) of biological specimens is performed from a series of images obtained over a range of tilt angles in a transmission electron microscope. When using the high voltage electron microscope (HVEM), various noises appear in EM images acquired from thick sections by high voltage electron beam. In order to obtain an adequate result in electron tomograms that allow visualization of rather complex and mega-cellular structure such as brain tissue, it is necessary to remove the noise in each original tilt images of thick section. Using band-pass filtering of original tilt images, the filtered images are obtained and used to assemble a reconstructed tomogram. The qualified 3D tomogram from filtered images results in a considerable reduction of the noises compared to conventional tomogram. In conclusion, this study suggests that band-pass filtering is effective to improve the brightness and intensity of HVEM produced tomograms acquired from micron-thick sections of biological specimens.

Rietveld Analysis of Nano-crystalline MnFe2O4 with Electron Powder Diffraction

  • Kim, Jin-Gyu;Seo, Jung-Wook;Cheon, Jin-Woo;Kim, Youn-Joong
    • Bulletin of the Korean Chemical Society
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    • 제30권1호
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    • pp.183-187
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    • 2009
  • The structure of nano-crystalline $MnFe_2O_4$ was determined and refined with electron powder diffraction data employing the Rietveld refinement technique. A nano-crystalline sample (with average crystal size of about 10.9 nm) was characterized by selected area electron diffraction in an energy-filtering transmission electron microscope operated at 120 kV. All reflection intensities were extracted from a digitized image plate using the program ELD and then used in the course of structure refinements employing the program FULLPROF for the Rietveld analysis. The final structure was refined in space group Fd-3m (# 227) with lattice parameters a=8.3413(7) $\AA$. The reliability factors of the refinement are $R_F$=7.98% and $R_B$=3.55%. Comparison of crystallographic data between electron powder diffraction data and reference data resulted in better agreement with ICSD-56121 rather than with ICSD-28517 which assumes an initial structure model.

Cryo-SEM Methodology of Arabidopsis thaliana Stem Using High-Pressure Freezing (고압동결고정을 이용한 애기장대 줄기의 cryo-SEM 분석법)

  • Choi, Yun-Joung;Lee, Kyung-Hwan;Je, A-Reum;Chae, Hee-Su;Jang, Ji-Hoon;Lee, Eun-Ji;Kweon, Hee-Seok
    • Applied Microscopy
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    • 제42권2호
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    • pp.111-114
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    • 2012
  • The scanning electron microscopy is an ideal technique for examining plant surface at high resolution. Most hydrate samples, however, must be fix and dehydrate for observation in the scanning electron microscope. Because the microscopes operate under high vacuum, most specimens, especially biological samples, cannot withstand water removal by the vacuum system without morphological distortion. Cryo-techniques can observe in their original morphology and structure without various artifacts from conventional sample preparation. Rapid cooling is the method of choice for preparing plant samples for scanning electron microscopy in a defined physiological state. As one of cryo-technique, high-pressure freezing allows for fixation of native non-pretreated samples up to $200{\mu}M$ thick and 2 mm wide with minimal or no ice crystal damage for the freezing procedure. In this study, we could design to optimize structural preservation and imaging by comparing cryo-SEM and convention SEM preparation, and observe a fine, well preserved Arabidopsis stem's inner ultrastructure using HPF and cryo-SEM. These results would suggest a useful method of cryo-preparation and cryo-SEM for plant tissues, especially intratubule and vacuole rich structure.

A Study on Crystalline Structural Variations of the Rigid Spherical-Tip scratch on the Surface of α-Titanium substrates via Molecular Dynamics Simulations (α-티타늄 평판표면에서 강체 구형팁의 스크래치로 인한 내부 결정구조 특성 변화에 대한 연구)

  • Yeri Jung;Jin Ho Kim;Taeil Yi
    • Tribology and Lubricants
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    • 제39권5호
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    • pp.167-172
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    • 2023
  • Titanium alloys are widely recognized among engineering materials owing to their impressive mechanical properties, including high strength-to-weight ratios, fracture toughness, resistance to fatigue, and corrosion resistance. Consequently, applications involving titanium alloys are more susceptible to damage from unforeseen events, such as scratches. Nevertheless, the impact of microscopic damage remains an area that requires further investigation. This study delves into the microscopic wear behavior of α-titanium crystal structures when subjected to linear scratch-induced damage conditions, utilizing molecular dynamics simulations as the primary methodology. The configuration of crystal lattice structures plays a crucial role in influencing material properties such as slip, which pertains to the movement of dislocations within the crystal structure. The molecular dynamics technique surpasses the constraints of observing microscopic phenomena over brief intervals, such as sub-nano- or pico-second intervals. First, we demonstrate the localized transformation of lattice structures at the end of initialization, indentation, and wear processes. In addition, we obtain the exerted force on a rigid sphere during scratching under linear movement. Furthermore, we investigate the effect of the relaxation period between indentation and scratch deformation. Finally, we conduct a comparison study of nanoindentation between crystal and amorphous Ti substrates. Thus, this study reveals the underlying physics of the microscopic transformation of the α-titanium crystal structure under wear-like accidental events.

Microscopic Domain Structures in NiO Exchange-coupled Films

  • Hwang, D.G.;Kim, J.K.;Kim, S.W.;Lee, S.S.;Dreyer, M.;Gomez, R.D.
    • Journal of Magnetics
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    • 제7권3호
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    • pp.94-97
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    • 2002
  • The dependence on nickel oxide thickness and a ferromagnetic layer thickness in unidirectional and isotropic exchange-coupled NiO/NiFe(Fe) bilayer films was investigated by magnetic force microscopy to better understand the relation between magnetic domain structure and exchange biasing at microscopic length scales. As the NiO thickness increased, the domain structure of unidirectional biased films formed smaller and more complex in-plane domains. By contrast, for the isotropically coupled films, large domains generally formed with increasing NiO thickness including a cross type domain with out-of plane magnetization orientation. The density of the cross domain is proportional to exchange biasing field, and the fact that the domain mainly originated from the strongest exchange coupled region was confirmed by imaging in an applied external field during a magnetization cycle.

Numerical Simulation of Blood Cell Motion in a Simple Shear Flow

  • Choi, Choeng-Ryul;Kim, Chang-Nyung;Hong, Tae-Hyub
    • Proceedings of the KSME Conference
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.1487-1491
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    • 2008
  • Detailed knowledge on the motion of blood cells flowing in micro-channels under simple shear flow and the influence of blood flow is essential to provide a better understanding on the blood rheological properties and blood cell aggregation. The microscopic behavior of red blood cell (RBCs) is numerically investigated using a fluid-structure interaction (FSI) method based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (smoothing and remeshing) in FLUENT (ANSYS Inc., USA). The employed FSI method could be applied to the motions and deformations of a single blood cell and multiple blood cells, and the primary thrombogenesis caused by platelet aggregation. It is expected that, combined with a sophisticated large-scale computational technique, the simulation method will be useful for understanding the overall properties of blood flow from blood cellular level (microscopic) to the resulting rheological properties of blood as a mass (macroscopic).

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Electron Microscopic Observation of Liposomes with Negative Stain (Liposomes의 음성염색에 의한 전자현미경적 관찰)

  • Ryu, Yong-Wun;Hong, Seong-Woon;Kim, Tae-Hwan
    • Applied Microscopy
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    • 제19권2호
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    • pp.1-16
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    • 1989
  • To investigate the research of the tumor seeker using liposomes with negatively stained. The fine structure and size in liposomes composed of PC, DSPC, DAPC and SM phospholipid were observed. And the yield of vesicle affected with sonication by mechanical force were determined. The results were as follows. 1. The stain of 2% UA are obtained a good resolution from electron microscopic observation to compare the negatively liposomes with PTA, AM and UA solution. 2. The fine structure of liposomes except DAPC, PC and CH alone samples could be observed from EM experiment of liposomes composed of PC, DSPC, DAPC and SM phospholipid. 3. The results of experiment from 10, 20, 40 and 60 times sonication with 30sec, prepared 0.1mM NTA-SM-liposomes were obtained unilamella vesicles from groups of multilamella vesicles of phospholipid. 4. About 50nm diameter liposomes obtained through membration filtration step to prepare homogenized liposomes.

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A Study on the Change of Urban Spatial Structure and Transformation of circumjacent Lot by Course of the Construction of Railroads and the Dismantlement of Eupseong in the Early 20th Century (20세기 초 철도부설과 읍성해체에 따른 도시공간구조와 주변 필지 변화에 관한 연구)

  • Kim, Dae-Jung;Cho, Jae-Mo
    • Journal of architectural history
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    • 제28권2호
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    • pp.31-40
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    • 2019
  • Considering the situation in the early 20th century when the existing urban system centered on urban areas began to change, the biggest factors causing urban structural changes in urban areas are construction of railroad and urban dismantling. The change process of Eupseong, in the microscopic viewpoint, can be understood as a process of change in the course of dismantlement of town's demarcation, improvement of accessibility and urban expansion due to the construction of railroads, process of urban expansion following the crumbling boundaries and structural changes. This study aimed to look at the transformation process of the Eupseong in the early 20th century, focusing on the demolition of the castle and the railway construction from a microscopic point of view of city.

Ultrastructure of the Eye in the Atypus coreanus Kim, 1985 (한국땅거미(Atypus coreanus Kim, 1985)의 시각기 미세구조)

  • Kwon, Jung-Kyun;Ko, Myung-Kyoo;Chung, Ho-Sam;Kim, Joo-Pil
    • Applied Microscopy
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    • 제28권4호
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    • pp.477-490
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    • 1998
  • Most spiders have four pairs of simple eyes. A few families of the spider have their developed eyes to an extent visual cues make up a significant of information to response from the external stimuli. Most spiders respond to the external stimuli around them. Specially, they are very sensitive to vibrations from the air, the ground, their webs, or even the surface of water. The present study was undertaken to examine the evolutionary development and function of eye with the observation of visual ultrastructure of Atypus coreanus Kim, 1985 using the electron microscopy. They have weak mobility, limited territory and low developed eyes. Atypus coreanus was collected from Mt. Ungil, Namyangju-gun, Kyonggi province. The fine structure of these eyes was examined by electron microscopy, and prepard by teasing method for scanning electron microscopic observation. As a result, the eyes of Atypus coreanus was composed of cornea, lens, vitreous body, retina, and rhabdome.

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