• Korean Journal of Plant Tissue Culture
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• v.26 no.1
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• pp.21-26
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• 1999

These experiments were attempted to introduce rolC gene in the Petunia hybrida cv. Titan white by Agrobacterium mediated. The maximum frequency of shoot regeneration was obtained by 60% on MS medium containing 1.0 mg/L BA, 0.1 mg/L NAA, 200 mg/L kanamycin, 500 mg/L carbenicillin, 30 g/L sucrose, and 8 g/L agar. Kanamycin-resistant calli were selected from petunia leaf discs by cocultivation with Agrobacterium suspension cultures on MS medium. The addition of AgNO$_3$ and KMnO$_4$ in the medium increased the shoot regeneration by 31.3% from leaf disc as compared with non-treated leaf disc. Among clones exhibiting kanamycin resistance, only 3 clones were confirmed by southern hybridization analysis.

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.159-163
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• 2002

A single phase perovskite relaxor ferroelectric PMN-PT-BT was prepared by a single calcination and the modified mixed oxide process. It was accomplished by ball-milling PbO, $Nb_2O_5,\;Ti(OC_3H_7)_4,\;BaCO_3,\;and\;Mg(NO_3)_2$ instead of MgO, removing the solvent, and then followed by calcination at 900$^{\circ}C$ for 2h. The specimen sintered at 1100$^{\circ}C$/2h showed the sintered density of 7.83 g/$cm^3$, room temperature dielectric constant of 22000, and dielectric loss of 2.5%. Addition of 1.0 mole% (0.3 wt%) of Ag as $AgNO_3$ and followed by calcination at 550$^{\circ}C$/2h lowered the sintering temperature to 900$^{\circ}C$. It still showed the sintered density of 7.88 g/$cm^3$, room temperature dielectric constant of 20000 and dielectric loss of 2.4%.

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.371-379
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• 2013

In order to improve the selective oxidation reaction of gaseous ammonia at a low temperature, various types of metal-impregnated activated alumina were prepared, and also physical and chemical properties of the conversion of ammonia were determined. Both types of metal (Cu, Ag) impregnated activated alumina show high conversion rate of ammonia at high temperature (over $300^{\circ}C$). However, at lower temperature ($200^{\circ}C$), Ag-impregnated catalyst shows the highest conversion rate (93%). In addition, the effects of lattice oxygen of the developed catalyst was studied. Ce-impregnated catalyst showed higher conversion rate than commercial alumina, but also showed lower conversion rate than Ag-impregnated sample. Moreover, 5 vol.% of Ag activation under hydrogen shows the highest conversion rate result. Finally, through high conversion at low temperature, it was considered that the production of NO and $NO_2$, toxic by-products, were effectively inhibited.

• Korean Journal of Materials Research
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• v.15 no.12
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• pp.791-795
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• 2005

In this study, aluminum borate whisker reinforced Mg-3Al-2Ag-1Zn matrix composites were fabricated by the squeeze infiltration technique. The purpose is to develop materials for elevated temperature applications. Microstructure observation revealed successful fabrication of the metal matrix composites, namely no cast defects such as porosity and matrix/reinforcement interface delamination etc. High temperature hardness and creep rupture properties were improved significantly with addition of Ag to the Al borate whisker reinforced Mg alloy composite. $Mg_3Ag$ phase formed during aging heat treatment could improve creep properties of the Mg matrix composites.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1080-1086
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• 2005

Membranes prepared from Vibrio natriegens oxidized both NADH and deamino-NADH as substrates. The maximum activity of the membrane-bound NADH oxidase was obtained at about pH 8.5 in the presence of 0.2 M NaCl, whereas that of the NADH:ubiquinone oxidoreductase was obtained at about pH 7.5 in the presence of 0.2 M NaCl. Electron transfer from NADH or deamino-NADH to ubiquinone-l or oxygen generated a considerable membrane potential (${\Delta}{\psi}$), which occurred even in the presence of $20{\mu}M$ carbonylcyanide m-chlorophenylhydrazone (CCCP). However, the ${\Delta}{\psi}$ was completely collapsed by the combined addition of $10{\mu}M$ CCCP and $20{\mu}M$ monensin. On the other hand, the activity of the NADH oxidase and the ${\Delta}{\psi}$ generated by the NADH oxidase system were inhibited by about $90\%$ with $10{\mu}M$ HQNO, whereas the activity of the NADH:ubiquinone oxidoreductase and the ${\Delta}{\psi}$ generated at the NADH:ubiquinone oxidoreductase segment were inhibited by about $60\%$. Interestingly, the activity of the NADH:ubiquinone oxidoreductase and the ${\Delta}{\psi}$ generated at the NADH:ubiquinone oxidoreductase segment were resistant to the respiratory chain inhibitors such as rotenone, capsaicin, and $AgNO_3$, and the activity of the NADH oxidase and the ${\Delta}{\psi}$ generated by the NADH oxidase system were very sensitive only to $AgNO_3$. It was concluded, therefore, that V. natriegens cells possess a $AgNO_3$-resistant respiratory $Na^+$ pump that is different from the $AgNO_3$-sensitive respiratory $Na^+$ pump of a marine bacterium, Vibrio alginolyticus.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.4
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• pp.242-246
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• 2005

Silver nanoparticles were synthesized by liquid phase reduction method from aqueous silver nitrate solution and borohybride as a reduction agent. The morphology, particle size and shape were influenced by the reaction conditions such as the concentration of $AgNO_3$, a reduction agent and addition of surfactant. The particle size decreased with decreasing the concentration of silver nitrate and using a borohydride. The obtained Ag particles showed the spherical shape with the range of 10-20 nm.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.131-131
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• 2010

We compared the electrical, optical, structural, and interface properties of indium zinc oxide (IZO)-Ag-IZO and IZO-Au-IZO multilayer electrodes deposited by linear facing target sputtering system at room temperature for organic photovoltaics. The IZO-Ag-IZO and IZO-Au-IZO multilayer electrodes show a significant reduction in their sheet resistance (4.15 and 5.49 Ohm/square) and resistivity ($3.9{\times}10^{-5}$ and $5.5{\times}10^{-5}$Ohm-cm) with increasing thickness of the Ag and Au layers, respectively. In spite of its similar electrical properties, the optical transmittance of the IZO-Ag-IZO electrode is much higher than that of the IZO-Au-IZO electrode, due to the more effective antireflection effect of Ag than Au in the visible region. In addition, the Auger electron spectroscopy depth profile results for the IZO/Ag/IZO and IZO/Au/IZO multilayer electrodes showed no interfacial reaction between the IZO layer and Ag or Au layer, due to the low preparation temperature. To investigate in detail the Ag and Au structures on the bottom IZO electrode with increasing thickness, a synchrotron x-ray scattering examination was employed. Moreover, the OSC fabricated on the IZO-Ag-IZO electrode shows a higher power conversion efficiency (3.05%) than the OSC prepared on the IZO-Au-IZO electrode (2.66%), due to its high optical transmittance in the wavelength range of 400-600 nm, which is the absorption wavelength of the P3HT:PCBM active layer.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.453-464
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• 2014

The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables ($AgNO_3$ concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM $AgNO_3$ (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

• Korean Journal Plant Pathology
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• v.14 no.3
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• pp.260-267
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• 1998

This study was undertaken to find a new formulation of soil amendment, and selection of antogonists and to effectively control brown and large patch of turfgrasses caused by Rhizoctoniz solani AG1-1 and AG 2-2. Fourteen inorgainc chemicals (1%, w/w) were added individually in vitro, and some chemicals showed suppressiveness to R. solani. Alum suppressed effectively mycelial growth of R. solani in the range of 17 to 77% as compared with control. The four chemicals such as Al2(SO4)3, alum, CaO, and NH4NO3 were finally selected. Out of three organic compounds, composted pine bark (CPB) showed prominent suppressive effect as compared with milled alfalfa and pine leaves. After inoculation of R. solani isolates AG-1 and AG2-2 on the turf seedlings, water soaked lesions and blight symptoms were developed on the whole seedlings. According to inhibition zone method, mycelial growth of the fungus were greatly suppressed by culture filterates of the antagonists, Gliocladium virens (Gl1-) and Pseudomonas sp. (P713). CPB soil amendment mixed with antagonists (1% w/w) controlled not only brown and large patch of turfgrasses, but also promote the good growth of the seedlings. In addition, the controlling effect was maintained more than 30 days. Especially, the controlling effect of two antagonists was similar to Cㅖㅠ soil amendment with the antagonists and also stimulated a favorable growth of the seedlings. Therefore, its is expected that continuous control of Rhizoctonia blight of turfgrasses can be obtained in field by subsequent applications of the antagonists.

• Journal of Environmental Health Sciences
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• v.39 no.4
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• pp.369-375
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• 2013

Objectives: This study was conducted to identify factors determining the toxicity of manufactured silver nano-particles (AgNPs) on aquatic organisms. Methods: For this purpose, we prepared several AgNPs with varied characteristics, including hydrodynamic size (nano-$^{ABC}Ag^{Cit}\;vs$-sized-$^{ABC}Ag^{Cit}$), impurities ($^{ABC}Ag$ stock vs $^{ABC}Ag$), and citrate capping ($^{ABC}Ag^{Cit}$), using a commercially available manufactured AgNP ($^{ABC}Ag$ stock). Acute tests were conducted using larval zebrafish (Danio rerioI). In addition, in order to determine the ecotoxicological potentials of various capping agents, toxicity tests were conducted with microbes, waterfleas, and fish for eight different capping agents that are used for NPs. Results: The toxicity of AgNPs in terms of 96 h fish $LC_{50}$ increased in the following order: $^{ABC}Ag$ stock < $^{ABC}Ag=^{ABC}Ag^{Cit}=nano-^{ABC}Ag^{Cit}$ < ${\mu}$-sized-$^{ABC}Ag^{Cit}$ < $AgNO_3$. After removing impurities by dialysis, 96 h $LC_{50}$ value decreased significantly from $126.6{\mu}g/L$ (95% confidence intervals [CI]: 107.0-146.2) ($^{ABC}Ag$ stock) to $78.6{\mu}g/L$ (CI: 72.7-84.8) ($^{ABC}Ag$). For ${\mu}$-sized-$^{ABC}Ag^{Cit}$ (ranging between 3.9 and 40.6 nm) and $^{ABC}Ag^{Cit}$ (40.6 nm and $9.1{\mu}m$), the 96 h $LC_{50}$ of the former ($43.9{\mu}g/L$, CI: 36.0-51.7) was approximately two-fold lower than that of the latter ($87.0{\mu}g/L$, CI: 73.5-100.3). Conclusions: In this study, we found that for acute lethality, the contribution of impurities and particle size was significant, but that of citrate was negligible.