• Applied Microscopy
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• 제48권4호
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• pp.96-101
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• 2018

The release of nanoscale membrane-bound vesicles is common in all three domains of life. These vesicles are involved in a variety of biological processes such as cell-to-cell communication, horizontal gene transfer, and substrate transport. Prokaryotes including bacteria and archaea release membrane vesicles (MVs) (20 to 400 nm in diameter) into their extracellular milieu. In spite of structural differences in cell envelope, both Gram-positive and negative bacteria produce MVs that contain the cell membrane of each bacterial species. Archaeal MVs characteristically show surface-layer encircling the vesicles. Filamentous fungi and yeasts as eukaryotic microbes produce bilayered exosomes that have varying electron density. Microbes also form intracellular vesicles and minicells that are similar to MVs and exosomes in shape. Electron and fluorescence microscopy could reveal the presence of DNA in MVs and exosomes. Given the biogenesis of extracellular vesicles from the donor cell, in situ high-resolution microscopy can provide insights on the structural mechanisms underlying the formation and release of microbial extracellular vesicles.

• 대한의생명과학회지
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• 제2권2호
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• pp.257-265
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• 1996

토끼 바이러스성 출혈증의 원인체를 실험 토끼에 접종하여 증식을 유도하고 간장에서 hematoxylin & eosin 염 색 에서 조직학적 진단과 세포내 viral RNA의 소재를 결정하기 위해 post-unicryl 포매한 block의 절편을 사용하여 단 염색과 전자현미경적 in situ hybridization을 시도하였다. 토끼 출혈증 viral RNA의 보합 결합에 이용하는 probe는 4717에서 4800(84bases)까지 oligonucleotide를 5'말단에 biotin-CE phosphoramidite로 표지하여 사용하였다. 보합결합물의 증명은 신호 표지로서 antibiotin antibody-l0nm gold를 사용하였으며, hybridization이나 증명은 기존 protocol에서 약간의 변법을 사용하였다. 0.02% glutaraldehyde에서 고정하고 unicryl resin 포매한 표본, biotinylated oligonucleotide probe, antibiotin antibody-l0nm gold로 실험한 결과 증강된 신호를 얻을 수 있었다. 특히 전처리를 생략하므로써 실험 과정을 간단하게 하여 신속한 결과를 얻을 수가 있었다. 전자현미경 in situ hybridization을 통하여 토끼 출혈증 바이러스의 주요 표적은 간세포로 감염 세포의 세포질 내 미토콘드리아와 핵 사이에서 immune gold입자가 뚜렷하게 표지 됨으로서 viral RNA를 증명할 수 있었다.

• 마이크로전자및패키징학회지
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• 제12권4호통권37호
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• pp.281-287
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• 2005

공정조성의 SnPb 솔더 선형시편에서 electromigration 현상을 실시간 주사전자현미경을 이용하여 관찰하였다. 공정조성 SnPb 솔더시편에 대한 electronigration 실험은 ${\times}10^4A/cm^2,\;90^{\circ}C$에서 실시하였다. 주사전자현미경 챔버 내에서 진행되는 electromigration 실험 동안 음극의 보이드 형성과 양극의 힐록 성장을 실시간으로 관찰하였다. 음극에서 일어나는 보이드 크기를 실시간 관찰한 결과, 공정조성 SnPb 솔더의 electromigration 거동은 보이드 형성 전에 가지는 잠복기의 존재를 명확히 알 수 있었고, 본 결과는 electromigration 거동으로 인한 플립칩 솔더 범프의 보이드 생성에 대한 잠복기와 관련이 있었다.

• 분석과학
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• 제8권4호
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• pp.723-730
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• 1995

Cyclic voltammetry and in situ STM were employed to examine the interfacial structures of a Pt(111) electrode in 0.1 mM KCN (pH9.5) and 0.1 mM KSCN (pH7) solutions. In situ STM atomic resolution revealed well ordered (2${\surd}$3${\times}$2${\surd}$3)$R30^{\circ}$-6CN and ($2{\times}2$)-2SCN structures within the double layer charging region. Six CN adsorbates formed a hollow hexagon, which embraced a coadsorbed $K^+$ cation. In contrast, the coadsorbed $K^+$ cations on the SCN covered Pt(111) were poorly ordered, despite adsorbed SCN formed a long range ordered ($2{\times}2$)-2SCN adlattice. In situ STM revealed the pronounced influence of potential in controlling the structures of compact layers at the proximity of a Pt electrode. Cathodic polarization facilitated the replacement of the coadsorbed cations by protons.

• 한국주조공학회지
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• 제24권3호
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• pp.159-164
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• 2004

The aim of the present work is to investigate the possibility of in-situ synthesis and net-shape forming of the titanium matrix (TiC+TiB) hybrid composites using a casting route. From the scanning electron microscopy, electron probe micro-analyzer, X-ray diffraction and thermodynamic calculations, the spherical TiC and needle like TiB reinforced hybrid titanium matrix composites could be obtained in-situ by the conventional melting and casting route between titanium and $B_4C$. No melt-mold reaction occurred between the titanium matrix (TiC+TiB) hybrid composites and the SKK mold, since the mold is consisted with interstitial and substitutional metal-mold reaction products. Not only the sound in-situ synthesis but also the economic net-shape forming of the titanium matrix (TiC+TiB) hybrid composites could be possible by the conventional casting route.

• Carbon letters
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• 제14권4호
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• pp.228-233
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• 2013

In this work, we report in-situ observations of changes in catalyst morphology, and of growth termination of individual carbon nanotubes (CNTs), by complete loss of the catalyst particle attached to it. The observations strongly support the growth-termination mechanism of CNT forests or carpets by dynamic morphological evolution of catalyst particles induced by Ostwald ripening, and sub-surface diffusion. We show that in the tip-growth mode, as well as in the base-growth mode, the growth termination of CNT by dissolution of catalyst particles is plausible. This may allow the growth termination mechanism by evolution of catalyst morphology to be applicable to not only CNT forest growth, but also to other growth methods (for example, floating-catalyst chemical vapor deposition), which do not use any supporting layer or substrate beneath a catalyst layer.

• Applied Microscopy
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• 제36권spc1호
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• pp.35-40
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• 2006

Self-assembled InAs/GaAs quantum dots (QDs) were grown by the atomic layer epitaxy (ALE) and molecular beam epitaxy (MBE) techniques, The structure and the thermal stability of QDs have been studied by high resolution electron microscopy with in-situ heating experiment capability, The ALE and MBE QDs were found to form a hemispherical structure with side facets in the early stage of growth, Upon capping by GaAs layer, however, the apex of QDs changed to a flat one. The ALE QDs have larger size and more regular shape than those of MBE QDs. The QDs collapse due to elevated temperature was observed directly in atomic scale, In situ heating experiment within TEM revealed that the uncapped QDs remained stable up to $580^{\circ}C$, However, at temperature above $600^{\circ}C$, the QDs collapsed due to the diffusion and evaporation of In and As from the QDs, The density of the QDs decreased abruptly by this collapse and most of them disappeared at above $600^{\circ}C$.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.197-201
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• 2009

A lot of work is carried out concerning to acicular ferrite formation in the weld metal of high strength and low-alloy steel. Those results are suggesting that oxides that contain titanium elements provides nucleation site of intragranular ferrite, referred as acicular ferrite. Thus, when intragranular ferrite is expected to form in heat-affected zone, oxide containing titanium element should be formed in the steel. However, normal steel is deoxidized by using aluminum element (Al-killed steel) with little oxygen content. It means almost oxygen is deoxidized with aluminum elements. In the present work, in order to form the acicular ferrite in the heat affected zone, with the same concept in the case of weld metal, the steel deoxidized with titanium element (titanium killed-steel) is prepared and the acicular ferrite formation is observed in detail by using laser-conforcal microscopy technique. The confocal technique makes it possible that the morphological change along the phase transformation from austenite to ferrite is in-situ tracked. Thus, the inclusion that stimulated the ferrite nucleation could be directly selected from the observed images, in the HAZ of the Ti-killed steel. The chemical composition of the selected inclusion is analyzed and the nucleation potential is discussed by changing the nucleation site with boron element. The potency for the ferrite nucleation is summarized and the existence of effective and ineffective manganese sulfide for nucleation is made clear.

• 한국전자현미경학회:학술대회논문집
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• 한국현미경학회 2003년도 제34차 춘계학술대회
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• pp.39-39
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• 2003

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1490-1500
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• 2024

Helium-induced defect nucleation and accumulation in polycrystalline W and W0.5 wt%ZrC (W0.5ZrC) were studied in-situ using the transmission electron microscopy (TEM) combined with 40 keV He⁺ irradiation at 800 and 1000℃ at the maximum damage level of 1 dpa. Radiation-induced dislocation loops were not observed in the current study. W0.5ZrC was found to be less susceptible to irradiation damage in terms of helium bubble formation and growth, especially at lower temperature (800 ℃) when vacancies were less mobile. The ZrC particles present in the W matrix pin the forming helium bubbles via interaction between C atom and neighbouring W atom at vacancies. This reduces the capability of helium to trap a vacancy which is required to form the bubble core and, as a consequence, delays, the bubble nucleation. At 1000 ℃, significant bubble growth occurred in both materials and all the present bubbles transitioned from spherical to faceted shape, whereas at 800 ℃, the faceted helium bubble population was dominated in W.