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111.
112.
Dokyung Yoon Daekwang Woo Jung Heon Kim Moon Ki Kim Taesung Kim Eung-Soo Hwang Seunghyun Baik 《Journal of nanoparticle research》2011,13(6):2543-2551
The cytotoxicity of alumina nanoparticles (NPs) was investigated for a wide range of concentration (25–200 μg/mL) and incubation
time (0–72 h) using floating cells (THP-1) and adherent cells (J774A.1, A549, and 293). Alumina NPs were gradually agglomerated
over time although a significant portion of sedimentation occurred at the early stage within 6 h. A decrease of the viability
was found in floating (THP-1) and adherent (J774A.1 and A549) cells in a dose-dependent manner. However, the time-dependent
decrease in cell viability was observed only in adherent cells (J774A.1 and A549), which is predominantly related with the
sedimentation of alumina NPs in cell culture medium. The uptake of alumina NPs in macrophages and an increased cell-to-cell
adhesion in adherent cells were observed. There was no significant change in the viability of 293 cells. This in vitro test
suggests that the agglomeration and sedimentation of alumina NPs affected cellular viability depending on cell types such
as monocytes (THP-1), macrophages (J774A.1), lung carcinoma cells (A549), and embryonic kidney cells (293). 相似文献
113.
114.
Noble C. Woo Kunigunde Cherenack Gerhard Tr?ster Ralph Spolenak 《Applied Physics A: Materials Science & Processing》2010,100(1):281-285
Reducing the strain in brittle device layers is critical in the fabrication of robust flexible electronic devices. In this
study, the cracking behavior of micro-patterned 500-nm-thick Ti films was investigated via uniaxial tensile testing by in
situ SEM and 4-point probe measurements. Both visual observations by SEM and 4-pt resistance measurements showed that strategically
patterned oval holes, off-set and rotated by 45°, had a significant effect on limiting the extent of cracking, specifically,
in preventing cracks from converging. Failure with regard to electrical conduction was delayed from less than 2% to more than
10% strain. 相似文献
115.
116.
Template‐Engaged Solid‐State Synthesis of Barium Magnesium Silicate Yolk@Shell Particles and Their High Photoluminescence Efficiency
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Dr. Xuncai Chen Prof. Dr. Woo‐Sik Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7190-7197
This study presents a new synthetic method for fabricating yolk@shell‐structured barium magnesium silicate (BMS) particles through a template‐engaged solid‐state reaction. First, as the core template, (BaMg)CO3 spherical particles were prepared based on the coprecipitation of Ba2+ and Mg2+. These core particles were then uniformly shelled with silica (SiO2) by using CTAB as the structure‐directing template to form (BaMg)CO3@SiO2 particles with a core@shell structure. The (BaMg)CO3@SiO2 particles were then converted to yolk@shell barium magnesium silicate (BMS) particles by an interfacial solid‐state reaction between the (BaMg)CO3 (core) and the SiO2 (shell) at 750 °C. During this interfacial solid‐state reaction, Kirkendall diffusion contributed to the formation of yolk@shell BMS particles. Thus, the synthetic temperature for the (BaMg)SiO4:Eu3+ phosphor is significantly reduced from 1200 °C with the conventional method to 750 °C with the proposed method. In addition, the photoluminescence intensity of the yolk@shell (BaMg)SiO4:Eu3+phosphor was found to be 9.8 times higher than that of the conventional (BaMg)SiO4:Eu3+ phosphor. The higher absorption of excitation light by the structure of the yolk@shell phosphor is induced by multiple light‐reflection and ‐scattering events in the interstitial void between the yolk and the shell. When preparing the yolk@shell (BaMg)SiO4:Eu3+ phosphor, a hydrogen environment for the solid‐state reaction results in higher photoluminescence efficiency than nitrogen and air environments. The proposed synthetic method can be easily extended to the synthesis of other yolk@shell multicomponent metal silicates. 相似文献
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118.
We consider a MAP-modulated fluid flow queueing model with multiple vacations. As soon as the fluid level reaches zero, the server leaves for repeated vacations of random length V until the server finds any fluid in the system. During the vacation period, fluid arrives from outside according to the MAP (Markovian Arrival Process) and the fluid level increases vertically at the arrival instance. We first derive the vector Laplace–Stieltjes transform (LST) of the fluid level at an arbitrary point of time in steady-state and show that the vector LST is decomposed into two parts, one of which the vector LST of the fluid level at an arbitrary point of time during the idle period. Then we present a recursive moments formula and numerical examples. 相似文献
119.
Sang Sub Kim Sun-Woo Choi Han Gil Na Dong Sub Kwak Yong Jung Kwon Hyoun Woo Kim 《Current Applied Physics》2013,13(3):526-532
ZnO–SnO2 branch–stem nanostructures were realized on a basis of a two-step process. In step 1, SnO2-stem nanowires were synthesized. In step 2, ZnO-branch nanowires were successfully grown on the SnO2-stem nanowires through a simple evaporation technique. We have pre-deposited thin Au layers on the surface of SnO2 nanowire stems and subsequently evaporated Zn powders on the nanowires. The ZnO branches, which sprouted from the SnO2 stems, had diameters in a range of 30–35 nm. As-synthesized branches were of single crystalline hexagonal ZnO structures. Since the branch tips were comprised of Au-containing nanoparticles, the Au-catalyzed vapor–liquid–solid growth mechanism was more likely to control the growth process of the ZnO branches. To test a potential use of ZnO–SnO2 branch–stem nanostructures in chemical gas sensors, their sensing performances with respect to NO2 gas were investigated, showing the promising potential in chemical gas sensors. 相似文献