• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.318-318
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• 2011

Etching of an ultrathin aluminum oxide film on NiAl(110) substrate by methanol is studied by home-built scanning tunneling microscopy at room-temperature. We deposited liquid methanol on thin alumina film by using a high speed solenoid valve suitable for deposition of thermally unstable molecules. It is found that only the reflection domain boundary between two domains was preferentially etched by methanol. Since the reflection domain boundary has many oxygen vacancies and irregular structures, judging from the fact, we assume that oxygen vacancies cause the chemically reactive phenomena of methanol in reflection domain boundary on an alumina film. The reactivity of the reflection domain boundary is attributed to the oxygen vacancies due to irregular structures. Similar reactivity is found on the oxygen deficient alumina produced on top of the intact alumina.

• Journal of Powder Materials
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• v.6 no.2
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• pp.171-177
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• 1999

Ti-45.2at.%Ni-5at.%Cu and Ti-40.2at.%Ni-10atat.%Cu alloy powders were fabricated by gas atomization process. The microstructures, Shape, hardness and phase transformation behaviors of the powders were investigated by means of optical microscopy, scanning electron microscopy, micro-hardness measurement, x-ray diffraction analyses and differential scanning calorimetry. The hardness of the Ti-Ni-XCu alloy powders decreased as Cu-content increased. The x-ray diffraction analyses were carried out for powders without heat treatment, and those that treated at 85$0^{\circ}C$ for an hour in a vaccum state($10^5$ torr) and then quenched into ice water. The intensity of B$19^t$ phase increased with heat treating. The monoclinic B$19^t$ martensite was formed in the Ti-Ni-XCu alloy powders during cooling.

• Journal of Powder Materials
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• v.2 no.3
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• pp.208-215
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• 1995

The aging effects on the characteristics of the melt spun Cu based shape memory alloys have been investigated by the microhardness test, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. After aged for specific times, hardness of the ribbons began to increase and shape memory capacity diminished. At the initial stage of aging the austenitic transformation temperatures increased gradually, but at last became nearly constant: That is, the aging deteriorated the thermal stability. The increase in hardness was due to the formation of the $\gamma_2$ precipitates. The loss in the shape memory capacity was due to the decrement of solute atoms in the matrix by the formation of the $\gamma_2$ precipitates. In this study, it was confirmed that Mn is an effective element for Improving the thermal stability.

• Applied Microscopy
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• v.13 no.1
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• pp.41-47
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• 1983

A Scanning electron microscope which can obtain additional information not readily available with either the light or transmission electron microscope was used to study the mast cell shape and its granules in normal mammal tissue(rat mesentery, stomach and mouse stomach) by fretting cut using liquid nitrogen. The results showed that rat mesentery and mouse stomach mast cell surfaces had no ridges and microvilli, but revealed several microvilli projecting into the surrounding connective tissue in the rat stomach mast cell. The shape of the mast cell varied from discoid(in the rat mesenteric mast cell) to ellipsoid (rat and mouse stomach), ranging from 7.5 to $10{\mu}m$ in diameter. The shape of the nucleus was ellipsoid and nucleic membrane was adherent to the outer surface of the granules. The granules, approximately 0.2 to $0.9{\mu}m$ in diameter, were various shapes. Frequently, rounded protrusions of cytoplasmic granules could be discerned under the cell membrane. Many small granules were seen in the cytoplasm.

• Applied Microscopy
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• v.27 no.4
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• pp.453-460
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• 1997

The tissue types of stromata were observed intensively in four species of Hypoxylon under a scanning electron microscope (SEM). These stromata were sectioned with a freezing fracture method for observation. Several tissue types were recognized and stable in each species. This study presents the most intensive observation of tissue types of each layer of stromata. It will be useful for taxonomic criteria for the species level. However, the tissue types can not be major taxonomical criteria for the genus Hypoxylon.

• Applied Microscopy
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• v.25 no.1
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• pp.86-95
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• 1995

This study was accomplished to investigate the ultrastructure of mucous glands in dorsal skin of frog (Rana catesbeiana) by means of scanning and transmission electron microscopes. The dorsal skin of Rana catesbeiana is composed of epidermis and dermis. The cutaneous mucous glands consist of inner glandular epithelial cells and outer myoepithelial cells. Glandular epithelial cells are divided into four types by the microscopic ultrastructure; ER-rich cell, round secretory granule-containing cell, foam-like granule mass-containing cell, mitochondria-rich cell. Myoepithelial cell has a long elliptical nucleus and filled with fibrous materials in the cytoplasm. As a result of scanning microscopic observation, the surface of dorsal skin is covered with cutaneous protrusions. The opening sites of the mucous glands are irregularly distributed in dorsal skin.

• Journal of Life Science
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• v.9 no.1
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• pp.45-49
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• 1999

Seaweed alginate was acetylated by activated carbon immobilized Pseudomonas syringae in a fluidized bed, up-flow reactor. The acetylation degree of seaweed alginate was about 30%. Calcium-acetylated seaweed alginate gel bead was made and compared to calcium-seaweed alginate gel bead by the scanning electron microscopy (SEM). Structural difference of two gel beads may results from increased viscosity and decreased affinity of acetylated seaweed alginate for calcium ion. On the basis of interior and exterior structure of calcium-acetylated seaweed alginate gels and property of acetylated seaweed alginate, it seems that acetylated seaweed alginate is used for the supporter for electrophoresis and packing materials for liquid chromatography and gel filtration.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.432-435
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• 2009

The preventive effect of chewing gum containing maltitol, xylitol, gum base, and sugar on remineralization were investigated. The clinical study consisted of 8 weeks' randomized, double blind, controlled, cross-over clinical trials including 24 healthy adults had chew gum. After each test week, remineralization effect was evaluated by measuring microhardness and scanning electron microscopy (SEM). Microhardness of experimental chewing gum containing maltitol or xylitol was significantly higher than that of sugar gum (p<0.005). Images of SEM showed the remineralization effect of gum containing gum base, maltitol, or xylitol compared with sugar gum. Maltitol and xylitol gums were more effective in remineralization than sugar gum. It was concluded that maltitol and xylitol can be used as sugar substitute to prevent dental caries.

• Carbon letters
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• v.15 no.1
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• pp.71-76
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• 2014

Activated carbon nanofibers (ACNF) were prepared from polyacrylonitrile (PAN)-based nanofibers using $CO_2$ activation methods with varying activation process times. The surface and structural characteristics of the ACNF were observed by scanning electron microscopy and X-ray diffraction, respectively. $N_2$ adsorption isotherm characteristics at 77 K were confirmed by Brunauer-Emmett-Teller and Dubinin-Radushkevich equations. As experimental results, many holes or cavernous structures were found on the fiber surfaces after the $CO_2$ activation as confirmed by scanning electron microscopy analysis. Specific surface areas and pore volumes of the prepared ACNFs were enhanced within a range of 10 to 30 min of activation times. Performance of the porous PAN-based nanofibers as an electrode for electrical double layer capacitors was evaluated in terms of the activation conditions.

• Journal of the Semiconductor & Display Technology
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• v.2 no.4
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• pp.31-35
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• 2003

We present a formation technique of thin film heater for heat transfer components. Thin film structures of Cr-Si have been prepared on top of alumina substrates by magnetron sputtering. More samples of Mo thin films were prepared on silicon oxide and silicon nitride substrates by electron beam evaporation technology. The electrical properties of the thin film structures were measured up to the temperature of $500^{\circ}C$. The thickness of the thin films was ranged to about 1 um, and a post annealing up to $900^{\circ}C$ was carried out to achieve more reliable film structures. In measurements of temperature coefficient of resistance (TCR), chrome-rich films show the metallic properties; whereas silicon-rich films do the semiconductor properties. Optimal composition between Cr and Si was obtained as 1 : 2, and there is 20% change or less of surface resistance from room temperature to $500^{\circ}C$. Scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) were used for the material analysis of the thin films.