• Applied Science and Convergence Technology
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• v.26 no.2
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• pp.34-41
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• 2017

A 2.45 GHz microwave plasma with linear antenna has been prepared for hydrophobic and wear-resistible surface coating of carbon steel. Wear-resistible properties are required for the surface protection of cutting tools and achieved by depositing a hydrogenated amorphous carbon film on steel surface through linear microwave plasma source that has $TE_{10}-TEM$ waveguide. Compared to the existing RF plasma source driven by 13.56 MHz, linear microwave plasma source can easily generate high density plasma and provide faster deposition rate and wider process windows. In this study, $Ar/CH_4$ gas mixtures are used for hydrogenated amorphous carbon film deposition. When microwave power of 1000 W is applied, 40 cm long uniform $Ar/CH_4$ plasma could be obtained in gas pressure of 200~400 mTorr. The Vickers hardness measurement of hydrogenated amorphous carbon film on steel surface was evaluated. It was found the optimized deposition condition at $Ar:CH_4=25:25$ sccm, 300 mTorr with microwave power of 1000W and RF bias power of 100W. By deposition of hydrogenated amorphous carbon film, contact angle on steel surfaces increases from $43.9^{\circ}$ to $93.2^{\circ}$.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.178-184
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• 2010

The aim of this work is the fabrication of polyelectrolyte microcapsules composed of biocompatible polymers such as chitosan, heparin and alginate, to encapsulate the fluorescein isothiocyanate(FITC)-albumin, and to investigate the protein release behavior therefrom. Polyelectrolyte capsules with 4-layer structures could be prepared with biocompatible materials by oppositely charged adsorption using melamin-foramide as a template. Transmission electron microscope(TEM), scanning electron microscope(SEM) and optical microscope confirmed hollow capsule structures. Protein release before and after encapsulation was monitored with a UV-Vis spectrometer. Microcapsules have different behaviors depending on the kind of polyelectrolyte polymers, chitosan-heparin capsules or chitosan-alginate capsules. In conclusion, the polyelectrolyte multilayer shells can be switched between an open and closed state by means of tuning the pH value.

• Applied Microscopy
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• v.26 no.1
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• pp.95-104
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• 1996

A comprehensive methodology to characterize the interfacial reaction products of $SiC_p/2024$ Al composites is introduced on the basis of the experimental results obtained using XRD, SEM and TEM. XRD performed on the electrochemically extracted $SiC_p$ and bulk $SiC_p/2024$ Al composite have shown that the interfacial reaction products consist of $Al_{4}C_3$ having hexagonal crystallographic structure, pure eutectic Si having diamond cubic crystallographic structure, and $CuAl_2$, having tetragonal crystalloraphic structure, respectively. According to the images observed by SEM, $Al_{4}C_3$, which has been reported to have needle shape, has a hexagonal platelet-shape and eutectic Si is found to have a dendritic shape. In addition eutectic $CuAl_2$, was observed to form near interface and/or along the grain boundaries. In order to confirm the results obtained by XRD, the primitive cell volume and reciprocal lattice height of such interfacial reaction products were calculated using the data obtained from convergent beam electron diffraction (CBED) patterns, and then compared with theoretical values.

• Applied Microscopy
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• v.28 no.2
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• pp.127-137
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• 1998

This study was observed of the skin that changed after irradiation of the ultraviolet A. All the mouse were hairless which the weight are about 25g and the ages $6\sim8$ weeks old. The mouse were divided into six groups; control, irradiated for 6 hours, 3 days, 7 days, 14 days, 21 days and 28 days. Each group was irradiated with ultraviolet that is $320nm\sim366nm$ of wavelengths. After irradiated, the skin was observed with the electron microscope and the light microscope. The results are as follow: 1) Light microscopy With following irradiation, the epidermis was not changed to most groups but at the 28 days group was thickened and deposit the melanocyte. The elastic fibers within the epidermis were thickened and twisted with following irradiation. 2) Eelectron microscopy The elastic fibers were slightly clumped at 6 hours group, mildly increased and partly aggregated in the 3 days group, branched and tangled at 7 days group, irregulated and electron density at 14 days group, sightly thickened and twisted at 21 days group, and randomly arranged, shortened, twisted, and electron density at 28 days group.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.549-576
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• 1995

Bacteria are one of the most important causative agents of the pulpal and periapical diseases. Streptococci are one of the most frequently isolated facultative anarerobic bacteria in the infected root canals. Bacterial cell wall components have a direct effect in the pathogenesis of the pulpal and periapical infections. Hyaluronidase produced by bacteria has been implicated in dissemination of the diseases. The purpose of this study was to evaluate the effect of cell wall extract of streptococci on the L929 cells using inverted microscope and the transmission electron microscopy (TEM). Hyaluronidase production of streptococcal strains were investigated to determine the correlation between the severity of cell damage and the activity of enzymes. Bacterial cell wall extracts of S. sanguis, S. mitis and S. uberis isolated from infected root canals and ATCC type strains of S. mutans (ATCC 10449) and E. faecalis (ATCC 19433) were prepared by sonication and confirmed with SDS-PAGE. Silver stain of SDS-PAGE of sonic extract was efficient at $100{\mu}g$/ml concentration of cell wall protein, while Coomasie blue stain was efficient at $100{\mu}g$/ml concentration. Inverted microscope showed that sonic extract-treated L929 cells were round and detached from the substratum while others lost their fibroblastic shapes. Transmission electron microscopic examination revealed that streptococcal extracts induced death of L929 cells. Sonic extracts of streptococci had variable effect on microstructure of L929 cells. significant chromatin condensation was observed in the nucleus of the cells. Disappearance of cell surface microvilli and nuclear fragments with dense chromatin were observed. The cell nucleus had an irregular shape and numerous large vacuoles were seen in the cytoplasm and some breaks of the cell membrane could be seen. Cell organelles were in various stages of destruction and cristae of mitochondria were disoriented or disappeared. Eighteen strains of streptococci did not produce hyaluronidase.

• Macromolecular Research
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• v.16 no.6
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• pp.549-554
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• 2008

Proton conducting crosslinked membranes were prepared using polymer blends of polystyrene-b-poly(hydroxyethyl acrylate)-b-poly(styrene sulfonic acid) (PS-b-PHEA-b-PSSA) and poly(vinyl alcohol) (PVA). PS-b-PHEA-b-PSSA triblock copolymer at 28:21:51 wt% was synthesized sequentially using atom transfer radical polymerization (ATRP). FT-IR spectroscopy showed that after thermal ($120^{\circ}C$, 2 h) and chemical (sulfosuccinic acid, SA) treatments of the membranes, the middle PHEA block of the triblock copolymer was crosslinked with PVA through an esterification reaction between the -OH group of the membrane and the -COOH group of SA. The ion exchange capacity (IEC) decreased from 1.56 to 0.61 meq/g with increasing amount of PVA. Therefore, the proton conductivity at room temperature decreased from 0.044 to 0.018 S/cm. However, the introduction of PVA resulted in a decrease in water uptake from 87.0 to 44.3%, providing good mechanical properties applicable to the membrane electrode assembly (MEA) of fuel cells. Transmission electron microscopy (TEM) showed that the membrane was microphase-separated with a nanometer range with good connectivity of the $SO_3H$ ionic aggregates. The power density of a single $H_2/O_2$ fuel cell system using the membrane with 50 wt% PVA was $230\;mW/cm^2$ at $70^{\circ}C$ with a relative humidity of 100%. Thermogravimetric analysis (TGA) also showed a decrease in the thermal stability of the membranes with increasing PVA concentration.

• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.416-424
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• 2018

Microstructure of oxide formed on Zr-Nb-Sn tube sample was intensively examined by scanning transmission electron microscopy after exposure to simulated primary water chemistry conditions of various concentrations of Zn (0 or 30 ppb) and dissolved hydrogen ($H_2$) (30 or 50 cc/kg) for various durations without applying desirable heat flux. Microstructural analysis indicated that there was no noticeable change in the microstructure of the oxide corresponding to water chemistry changes within the test duration of 100 days (pretransition stage) and no significant difference in the overall thickness of the oxide layer. Equiaxed grains with nano-size pores along the grain boundaries and microcracks were dominant near the water/oxide interface, regardless of water chemistry conditions. As the metal/oxide interface was approached, the number of pores tended to decrease. However, there was no significant effect of $H_2$ concentration between 30 cc/kg and 50 cc/kg on the corrosion of the oxide after free immersion in water at $360^{\circ}C$. The adsorption of Zn on the cladding surface was observed by X-ray photoelectron spectroscopy and detected as ZnO on the outer oxide surface. From the perspective of $OH^-$ ion diffusion and porosity formation, the absence of noticeable effects was discussed further.

• ALGAE
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• v.28 no.4
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• pp.331-341
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• 2013

Rhinomonas reticulata var. atrorosea G. Novarino is a photosynthetic marine flagellate that is known to have typical characteristics of cryptomonads. We examined the flagellar apparatus of R. reticulata var. atrorosea by transmission electron microscopy. The major components of the flagellar apparatus of R. reticulata var. atrorosea consisted of four types of microtubular roots (1r, 2r, 3r, and mr), a non-keeled rhizostyle (Rhs), mitochondrion-associated lamella (ML), two connections between basal bodies, a striated fibrous root (SR) and a striated fiber-associated microtubular root (SRm). Four types of microtubular roots originated near the ventral basal body and extended toward the left side of the basal bodies. The non-keeled Rhs originated at the Rhs-associated striated fiber, which was located between two basal bodies and extended into the middle of the cell. The ML was a plate-like fibrous structure associated with mitochondria and originating from a Rhs-associated fiber. It split into two parts and extended toward the dorsal-posterior of the cell to a mitochondrion. The SR and SRm extended parallel to the anterior lobe of the cell. The overall configuration of the flagellar apparatus in R. reticulata var. atrorosea was similar to the previously reported descriptions of those of Cryptomonas paramecium, C. pyrenoidifera, C. ovata, Hanusia phi, Guillardia theta, and Proteomonas sulcata. However, the flagellar apparatus system of R. reticulata var. atrorosea was more complex than those of other cryptomonad species due to the presence of an additional microtubular root and other distinctive features, such as a rhizostyle-associated striated fiber and large ML.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.153-156
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• 2012

In this study, two different methods were studied to prepare Pt-Pd catalysts for direct methanol fuel cells in order to enhance the electrochemical efficiency. The catalysts were compared with simultaneously deposited Pt-Pd and sequentially deposited Pt-Pd. The electrocatalysts contained 20 wt% of metal loading on carbon black and 1 : 2 of Pt : Pd atomic ratio. Electrochemical properties of the catalysts were compared by measuring cyclic voltammetries and average sizes and lattice parameters were measured by transmission electron microscopy images and x-ray diffraction. As a result, sequentially deposited Pt-Pd/C catalysts showed better electrochemical properties than those of simultaneously deposited Pt-Pd/C catalysts.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1254-1260
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• 2008

The aim of the present study was to prepare nanosample of fucoidan using lecithin as encapsulated material and to investigate the anticancer and immunomodulatory activity of nanoparticle in vitro. The nanoparticles have been characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Confocal microscopy confirmed the internalization of the fucoidan conjugates into the immune cells. The uptake of nanoparticles was confirmed with confocal microscopy demonstrating their localization in the cells. The anticancer activity was increased over 5-10% in different cancer cells of fucoidan nanoparticle as compare with fucoidan. The human B and T cells growth and the secretion of interleukin-6 and tumor necrosis factor-a from B cell were also improved by fucoidan nanoparticle because of the rapid absorption of nanoparticle into the cells as compare to fucoidan. At 0.6 mg/mL concentrations, the fucoidan nanoparticle showed better activity than 1.0 mg/mL concentration in T cell growth because the cells reached their saturation capacity. When the fucoidan was encapsulated in lecithin, its anticancer as well as its immunomodulatory activity proved to be superior from that of itself in pure form.