• Journal of Digital Convergence
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• v.15 no.11
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• pp.513-522
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• 2017

We tried to analyze the inflammation reactions by treatment of AG, AS and AA in murine RAW 264.7 cells. To investigate the effect of AG, AS and AA on cell viability of RAW 264.7 cells, AG, AS and AA were treated for 24 h and MTS assay was performed. Cell viabilities were increased in $1,600{\mu}g/ml$ concentration by AS, AA and AG treatments, respectively. The mRNA expression levels of $IL-1{\beta}$, $TNF-{\alpha}$ and iNOS were increased by AG and AA treatment at a concentration of $200{\mu}g/ml$ in RAW 264.7 cells without Lipopolysaccharide (LPS) treatment. The mRNA expression levels of $IL-1{\beta}$, $TNF-{\alpha}$ and iNOS were increased by AG and AA 6 h treatment at a concentration of $200{\mu}g/ml$ with LPS treatment. In this study, we observed that AG, AS and AA show various activities on inflammation reaction depend on their treatment time. In the future, studies should be conducted to investigate the effects of AG, AS and AA on the various inflammatory responses of macrophages.

• Journal of the Korean Magnetics Society
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• v.8 no.3
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• pp.156-160
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• 1998

Crystal structures and magneto-optical properties of $(Mn_{0.5-Z}Sb_{0.5+Z})_{100-y}Pt_y$ (0$(Mn_{0.5-Z}Sb_{0.5+Z})_{100-y}Ag_y$ (0$^{\circ}C$ are C1b-type with fcc and NiAs-type with hcp, respectively. The MnSbAg films have a texture which the c-axis orientation is perpendicular to the film plane by annealing at 300 $^{\circ}C$ for less than 3 hours. The perpendicular anisotropy constants of the $Mn_{47.4}Sb_{47.5}Ag_{5.1}$ film annealed at 300 $^{\circ}C$ for 3 hours are $K_1=6.6{\times}10^5 \; erg/cm^3\;and\;K_2=1.9{\times}10^5\; erg/cm^3$. The Kerr rotation angle of MnSbPt films increases but that of MnSbAg film decreases by decreasing incident wavelength within the range of 700$\leq$ λ$\leq$1000 nm. High polar Kerr angles of 1.7$^{\circ}$ (λ =700 nm) and 0.6$^{\circ}$ (λ =1000 nm), 0.2$^{\circ}$ (λ =700 nm) and 0.97$^{\circ}$ (λ =1000 nm) have been obtained from $Mn_{41.1}Sb_{44,9}Pt_{14.0}$ and $Mn_{47.4}Sb_{47.5}Ag_{5.1}$ alloy films, respectively.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.62-62
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• 2018

Pt is still considered as one of the most active electrocatalysts for ORR in alkaline fuel cells. However, the high cost and scarcity of Pt hamper the widespread commercialization of fuel cells. As a strong candidate for the replacement of Pt catalyst, silver (Ag) has been extensively studied due to its high activity, abundance, and low cost. Ag is more stable than Pt in the pH range of 8~14 as the equilibrium potential of Ag/Ag+ being ${\approx}200mV$ higher than that of Pt/PtO. However, Ag is the overall catalytic activity of Ag for oxygen reduction reaction(ORR) is still not comparable to Pt catalyst since the surface Ag atoms are approximately 10 times less active than Pt atoms. Therefore, further enhancement in the ORR activity of Ag catalysts is necessary to be competitive with current cutting-edge Pt-based catalysts. We demonstrate the architectural design of Ag catalysts, synthesized using plasma discharge in liquid phase, for enhanced ORR kinetics in alkaline media. An attractive feature of this work is that the plasma status controlled via electric-field could form the Ag nanowires or dendrites without any chemical agents. The plasma reactor was made of a Teflon vessel with an inner diameter of 80 mm and a height of 80 mm, where a pair of tungsten(W) electrodes with a diameter of 2 mm was placed horizontally. The stock solutions were made by dissolving the 5-mM AgNO3 in DI water. For the synthesis of Agnanowires, the electricfield of 3.6kVcm-1 in a 200-ml AgNO3 aqueous solution was applied across the electrodes using a bipolar pulsed power supply(Kurita, Seisakusyo Co. Ltd). The repetition rate and pulse width were fixed at 30kHz and 2.0 us, respectively. The plasma discharge was carried out for a fixed reaction time of 60 min. In case of Ag nanodendrites, the electric field of 32kVcm-1 in a 200-ml AgNO3 aqueous solution was applied and other conditions were identical to the plasma discharge in water in terms of electrode configuration, repetition rate and discharge time. Using SEM and STEM, morphology of Ag nanowires and dendrites were investigated. With 3.6 kV/cm, Ag nanowire was obtained, while Ag dendrite was constructed with 32 kV/cm. The average diameter and legth of Ag nanowireses were 50 nm and 3.5 um, and thoes values of Ag dendrites were 40 nm and 3.0 um. As a results of XPS analysis, the surface defects in the Ag nanowires facilitated O2 incorporation into the surface region via the interaction between the oxygen and the electron cloud of the adjacent Ag atoms. The catalytic activity of Ag for oxygen reduction reaction(ORR) showed that the catalytic ORR activity of Ag nanowires are much better than Ag nanodendrites, and electron transfer number of Ag nanowires is similar to that of Pt (${\approx}4$).

• Korean Journal Plant Pathology
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• v.10 no.4
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• pp.314-318
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• 1994

Incidence of stem rot on carnation (Dianthus caryophyllus L.) ranged 11 to 29% in Namwon and Chongup area during the growing seasons from 1993 to 1994. Among 129 isolates from carnations in Namwon, 77 isolates were identified as Rhizoctonia solani, 38 isolates were Fusarium oxysporum and 14 isolates were not identified. Among 169 isolates in Chongup, 19 isolates were identified as R. solani, 106 isolates as F. oxysporum and 44 isolates were not identified. Among 77 isolates of R. solani isolated from the specimens of Namwon, 52 isolates were classified as anastomosis group AG 2-2 by anastomosis test, 14 isolates as AG 2-1 and 11 isolates as AG 4. Among 19 isolates from specimens of Chongup, 14 isolates were classified as anastomosis group AG 2-2 and 5 isolates as AG 4. Pathogenicity tests revealed that isolates of F. oxysporum and R.solani AG 2-2 were highly virulent and isolates of R.solani AG 2-1 and AG 4 were mildly virulent.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.33-36
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• 2016

In the present work, a Ni-doped indium zinc oxide (NIZO) film and its multilayers with Ag layers were investigated as transparent conducting electrodes for liquid crystal display (LCD) applications, as a substitute for indium tin oxide (ITO) electrodes. By interposing the Ag layer between the NIZO layers, the loss of the optical transmittance occurred; however, the Ag layer brought enhancement of electrical sheet resistance to the NIZO/Ag/NIZO multilayer electrode. The twisted nematic cell based on the NIZO/Ag/NIZO multilayer electrode exhibited superior electro-optical characteristics than those based on single NIZO electrode and was competitive compared to those based on the conventional ITO electrode. An LCD-based NIZO/Ag/NIZO multilayer electrode may allow new approaches to conventional ITO electrodes in display technology.

• Journal of Sensor Science and Technology
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• v.28 no.4
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• pp.266-269
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• 2019

In this study, $Ag_2Se$ nanoparticles were synthesized by employing the colloidal method. The synthesized $Ag_2Se$ nanocrystals were spherical in shape with a diameter of approximately 4 nm and had high crystallinity. These attributes of $Ag_2Se$ nanocrystals were determined through images obtained from a high resolution transmission electron microscope. Thin films comprising the synthesized $Ag_2Se$ nanoparticles had an optical band gap of 1.5 eV. Furthermore, fabricated NIR sensors comprising $Ag_2Se$ nanoparticles exhibited a high detectivity of $5.5{\times}10^9$ Jones (above $1{\times}10^9$) at room temperature, leading to low power consumption

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.84-89
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• 2014

In this work, Ag-$TiO_2$ nanocomposites were prepared via the sonochemical deposition of Ag nanometals on $TiO_2$ nanoparticles. The size of deposited Ag nanometals was ranged in 1~3 nm and the number of Ag nanometals deposited on $TiO_2$ increased in proportion to the dosage amounts of Ag precursors. As-prepared Ag-$TiO_2$ was loaded on the sterilized agar plate together with an aliquot volume of diluted E-coli, followed by 30 min irradiation of the solar simulated light ($600{\sim}1800{\mu}w/cm^2$). Finally, the agar plate was incubated for 24 h at $37^{\circ}C$ and the number of survived colonies were counted. It was experimentally confirmed that Ag-$TiO_2$ exhibited the higher antimicrobial activity than that of pure $TiO_2$, based on measuring the colony number of control sample. The survived colony numbers on the agar plate decreased with the increase of dosage amounts of Ag-$TiO_2$ and the irradiated intensity of solar simulated light for 30 min before incubating. The increase of Ag nanometal doposition induced the progressive enhancement of antimicrobial activity, but rather reduced the photocatalytic activity of Ag-$TiO_2$ probably due to the excessive presence of Ag nanometals on $TiO_2$ matrix.

• Toxicological Research
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• v.28 no.1
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• pp.19-24
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• 2012

In the present study, toxicity of silver nanoparticles (AgNPs) was investigated in the nematode, Caenohabditis elegans focusing on the upstream signaling pathway responsible for regulating oxidative stress, such as mitogen-activated protein kinase (MAPK) cascades. Formation of reactive oxygen species (ROS) was observed in AgNPs exposed C.elegans, suggesting oxidative stress as an important mechanism in the toxicity of AgNPs towards C. elegans. Expression of genes in MAPK signaling pathways increased by AgNPs exposure in less than 2-fold compared to the control in wildtype C.elegans, however, those were increased dramatically in sod-3 (gk235) mutant after 48 h exposure of AgNPs (i.e. 4-fold for jnk-1 and mpk-2; 6-fold for nsy-1, sek-1, and pmk-1, and 10-fold for jkk-1). These results on the expression of oxidative stress response genes suggest that sod-3 gene expression appears to be dependent on p38 MAPK activation. The high expressions of the pmk-1 gene 48 h exposure to AgNPs in the sod-3 (gk235) mutant can also be interpreted as compensatory mechanisms in the absence of important stress response genes. Overall results suggest that MAPK-based integrated stress signaling network seems to be involved in defense to AgNPs exposure in C.elegans.

• Korean Journal of Materials Research
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• v.15 no.9
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• pp.598-603
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• 2005

To develope new lead-free solders with the melting temperature close to that of Sn-37Pb$(183^{\circ}C)$, Sn-0.7Cu-5Pb-1Ga, Sn-0.7Cu-5Pb-1Ag, Sn-0.7Cu-5Pb-5Bi-1Ag, and Sn-0.7Cu-SBi-1Ag alloys were composed by adding low-netting elements such as Ga, Bi, Pb, and Ag to Sn-0.7Cu. Then the melting temperatures, microstructures, wettability, and adhesion properties of these alloys were evaluated. DSC analysis showed that the melting temperature of Sn-0.7Cu-SPb-1Ga was $211^{\circ}C$, and those of other alloys was in the range of $192\~200^{\circ}C$. Microstructures of these alloys after heat-treatment at $150^{\circ}C$ for 24 hrs were basically composed of coarsely- grown $\beta-Sn$ grains, and $Cu_6Sn_5$ and $Ag_3Sn$ intermetallic precipitates. Sn-0.7Cu-5Pb-1Ga and Sn-0.7Cu-5Pb-5Bi-1Ag showed excellent wettability, while Sn-0.7Cu-5Bi-1Ag and Sn-0.7Cu-5Pb-5Bi-1Ag revealed good adhesion strength with the Cu substrates. Among 4 alloys, Sn-0.7Cu-5Pb-5Bi-1Ag with the lowest melting temperature $(192^{\circ}C)$ and relatively excellent wettability and adhesion strength was suggested to be the best candidate solder to replace Sn-37Pb.

• Biomolecules & Therapeutics
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• v.5 no.4
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• pp.412-418
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• 1997

General pharmacological properties of AG 60 (mixture of acriflavine and guanosine (1:1, w/w)), which has anticancer effect, following intramuscular administration were examined in terms of effects on central nervous system, gastrointestinal system, cardiovascular system, respiratory system and autonomic nervous system in mice, rats, guinea-pigs and rabbits. AG 60 at the dose of 15 mgtg had no influences on pentobarbital sleeping time, spontaneous motor activity, chemoshock produced by pentylenetetrazole solution, writhing syndromes induced by 0.8% acetic acid solution, and motor coordination of mice. However, AG 60 at the dose of 7.5 and 15 mg/kg caused significant decrease of normal body temperature 1 and/or 2 h after the administration. No influence on body temperature was observed at 3.75 mg/kg in mice. Gastric secretion of rat and intestinal motility of mice were not influenced by the dose of 15 mg/kg. In terms of autonomic nervous system, AG 60 did not show direct effect and inhibitory or augmentative action of histamine- or acetylcholine-induced contractions at the concentration of 5 mg/L in the isolated ileum of guinea-pig. The administration of 15 mg/kg of AG 60 did not affect mean arterial blood pressure and heart rate in rat. AG 60 (15 mg/kg) given to anesthetized rabbits showed no effect on respiratory rate.