• Journal of the Korean Chemical Society
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• v.43 no.3
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• pp.315-320
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• 1999

Novel electroluminescent materials, polymer material, PU-BCN and low molar mass material, D-BCN with the same chromophores were designed and synthesized. A molecular structure of chromophore was composed of bisstyrylbenzene derivative with cyano groups as electron injection and transport and phenylamine groups as hole injection and transport. Device structures with PU-BCN and D-BCN as an emission layer were fa-bricated, which were a single-layer device(SL), Indium-tin oxide(ITO)/emission layer/MgAg, and two kinds of double-layer devices which were composed of ITO/emission layer/oxadiazole derivative/MgAg as a DL-E device and ITO/triphenylamine derivative/emission layer/MgAg as a DL-H device. The two emission materials, PU-BCN and D-BCN with the same emission-chromophore were evaluated as having excellent performance of charge injection and transport and revealed almost the same emission characteristics in high current density. EL emission maximum peaks of two material were detected at about 640 nm wavelength of red emission region.

• Journal of Plant Biotechnology
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• v.48 no.3
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• pp.173-178
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• 2021

Basal callus formation and leaf abscission is a problem in clonal micropropagation. We have described an in vitro clonal propagation protocol of Dalbergia sissoo Roxb (shisham) 'FRI-14' in which AgNO₃ played important role not only in mitigating problem of leaf abscission and basal callus, but also improved shoot induction and multiplication. Best induction and shoot multiplication was obtained on MS media with 1.5 mg/l 6-BAP and 10 mg/l AgNO₃ and half-strength MS media with 0.5 mg/l 6-BAP, 2 mg/l AgNO₃ and 50 mg/l Adenine sulphate whereas best ex vitro rooting was obtained with 200 mg/l IBA in pulse treatment.

• Corrosion Science and Technology
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• v.20 no.5
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• pp.315-323
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• 2021

In this study, we examined corrosion behaviors of two types of Pb alloys for a lead acid battery comparatively. One containing 6.6 wt% Sn, 36 mg/kg Bi, and 612.4 mg/kg Ca was prepared by twin-roll continuous casting. The other containing 5.2 wt% Sn, 30.5 mg/kg Ag, and 557 mg/kg Ca was made by twin-belt continuous casting. Potentiodynamic polarization tests were performed to evaluate corrosion resistance. Cyclic voltammetry was done to examine oxidation and reduction reactions occurring on the surface of each alloy in 4.8 M H₂SO₄ solution. Electrochemical test results implied that the Pb alloy prepared with the twin-belt casting method was less stable than that cast with the twin-roll method. Such results might be due to precipitations formed during the casting process. Rolling did not appear to affect the corrosion behavior of the twin-roll samples with Ag < 10 mg/kg, while it reduced the anodic reaction of Ag on the surface of the twin-belt sample with 30.5 mg/kg Ag.

• Journal of the Korean Magnetics Society
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• v.12 no.3
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• pp.94-98
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• 2002

Sputtering conditions and various underlayer such as Al, Cu, Ni, Cr, Ag, Mg, Fe, Co, Pd, Au, Pt, Mo and Hf were investigated for coercivity enhancement of 20 nm Ti/CoCrPt thin films in order to increase the coercivity of the films thinner than 20 nm. Among them, Ag and Mg were effective to increase the coercivity. Particularly 2 nm Ag was very effective to increase the coercivity and nucleation field as well as to reduce ${\alpha}$ value in CoCrPt thin film such that the coercivity of 2 nm Ag/18 nm Ti/10 nm CoCrPt film was 2200 Oe. However, it seemed that other coercivity enhancement mechanism operated in CoCrPt films because Ti (002) preferred texture was not developed with Ag underlayer contrary to a general expectation. And the coercivity and nucleation field were decreased when glass substrate with rougher surface was used.

• Journal of the Korean Vacuum Society
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• v.17 no.5
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• pp.442-447
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• 2008

Ferroelectric samples of the 0.65Pb$(Mg_{1/3}Ta_{2/3})O_3-0.35PbTiO_3$ modified with $Ag_2O$ were prepared by sintering at $1200^{\circ}C$ for 4 h. The fractured surface of sintered pellets were examined by scanning electron microscopy(SEM). The dielectric constant, loss, and pyroelectric coefficient of the ceramics samples were determined. The dielectric and pyroelectric properties could be improved with the addition of small amount of $Ag_2O$ up to 0.2 mol%. The dielectric and pyroelectirc peak temperatures are continuously shifted to lower temperature with addition of small amounts of $Ag_2O$.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.447-454
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• 2003

Samples were prepared by the solid-state reaction method. The nominal composition of the samples was B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+{delta}$ prepared from powder of B $i_2$ $O_3$, PbO, SrC $O_3$, CaC $O_3$, and CuO. They were pulverized, mixed with AgO, A $u_2$ $O_3$and MgO of 50 wt%. Finally, they were sintered at 820 to 85$0^{\circ}C$ in air. The structural characteristics, the microstructure of surface and the critical temperature with respect to the each samples were analyzed by XRD, $T_{c}$, SEM and EDS respectively. It was found that the the critical temperature of the silver oxide additive samples (99.58 K) is higher than those of gold or magnesium oxides additive samples, but all those values are lower than that of pure Bi-2223 phase. The microstructure of surface showed the tendency which the AgO additive samples become more minuteness than A $u_2$ $O_3$ and MgO additive samples.s.samples.s.

• Korean Journal of Plant Tissue Culture
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• v.26 no.4
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• pp.259-264
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• 1999

In order to study the role of ethylene on the formation of adventitious roots, trichomes and calli, the effects of 1-aminocyclopropane-l-carboxylic acid (ACC), ethephon, $CoCl_2$ and $AgNO_3$ were investigated in the leaf segments from ecotype Columbia of Arabidopsis thaliana. When the leaf segments were cultured on the media for forming adventitious roots (0.1 mg/L NAA), trichomes (2.0 mg/L NAA) and calli (10.0 mg/L NAA), and then each cultures was treated with 1-100 mg/L of ACC and ethephon, respectively. On the adventitious root-forming medium adventitious root formation was decreased, and trichomes were induced. And on the trichome-forming medium trichome formation was decreased, and calli were induced. In order hand each culture was treated with 1-100 mg/L of $CoCl_2$ and $AgNO_3$, respectively. On the adventitious root-forming medium adventitious roots was increased without trichome formation, and on the trichome-forming medium trichome formation was decreased, and adventitious roots were induced. However on the callus-forming medium treated with ACC, ethephon, $CoCl_2$ and $AgNO_3$, respectively, callus formation was inhibited and trichomes were induced in all cultures.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1114-1119
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• 2012

This study was conducted to assess the microbial toxicity of ionic silver solution ($Ag^+N$) and silver nanoparticle suspension ($Ag^0NP$) based on the Microtox bioassay. In this test, the light inhibition of luminescent bacteria was measured after 15 and 30 min exposure to aqueous solutions and soils spiked with a dilution series of $Ag^+N$ and $Ag^0NP$. The resulting dose-response curves were used to derive effective concentration (EC25, $EC_{50}$, EC75) and effective dose ($ED_{25}$, $ED_{50}$, $ED_{75}$) that caused a 25, 50 and 75% inhibition of luminescence. In aqueous solutions, $EC_{50}$ value of $Ag^+N$ after 15 min exposure was determined to be < $2mg\;L^{-1}$ and remarkably lower than $EC_{50}$ value of $Ag^0NP$ with $251mg\;L^{-1}$. This revealed that $Ag^+N$ was more toxic to luminescent bacteria than $Ag^0NP$. In soil extracts, however, $ED_{50}$ value of $Ag^+N$ with 196 mg kg-1 was higher than $ED_{50}$ value of $Ag^0NP$ with $104mg\;kg^{-1}$, indicating less toxicity of $Ag^+N$ in soils. The reduced toxicity of $Ag^+N$ in soils can be attributed to a partial adsorption of ionic $Ag^+$ on soil colloids and humic acid as well as a partial formation of insoluble AgCl with NaCl of Microtox diluent. This resulted in lower concentration of active Ag in soil extracts obtained after 1 hour shaking with $Ag^+N$ than that spiked with $Ag^0NP$. With longer exposure time, EC and ED values of both $Ag^+N$ and $Ag^0NP$ decreased, so their toxicity increased. The toxic characteristics of silver nanomaterials were different depending on existing form of Ag ($Ag^+$, $Ag^0$), reaction medium (aqueous solution, soil), and exposure time.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.3
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• pp.223-234
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• 2016

This study aimed to the adsorption-removal of high- radioactive iodide (I) contained in the initially generated high-radioactive seawater waste (HSW), with the use of AgX (Ag-impregnated X zeolite). Adsorption of I by AgX (hereafter denoted as AgX-I adsorption) was increased by increasing the Ag-impregnated concentration in AgX, and its concentration was suitable at about 30 wt%. Because of AgCl precipitation by chloride ions contained in seawater waste, the leaching yields of Ag from AgX (Ag-impregnated concentration : about 30~35 wt%) was less than those in distilled water (< 1 mg/L). AgX-I adsorption was above 99% in the initial iodide concentration ($C_i$) of 0.01~10 mg/L at m/V (ratio of weight of adsorbent to solution volume)=2.5 g/L. This shows that efficient removal of I is possible. AgX-I adsorption was found to be more effective in distilled water than in seawater waste, and the influence of solution temperature was insignificant. Ag-I adsorption was better described by a Freundlich isotherm rather than a Langmuir isotherm. AgX-I adsorption kinetics can be expressed by a pseudo-second order rate equation. The adsorption rate constants ($k_2$) decreased by increasing $C_i$, and conversely increased by increasing the ratio of m/V and the solution temperature. This time, the activation energy of AgX-I adsorption was about 6.3 kJ/mol. This suggests that AgX-I adsorption is dominated by physical adsorption with weaker bonds. The evaluation of thermodynamic parameters (a negative Gibbs free energy and a positive Enthalpy) indicates that AgX-I adsorption is a spontaneous reaction (forward reaction), and an endothermic reaction indicating that higher temperatures are favored.

• Journal of the Korean Chemical Society
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• v.17 no.4
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• pp.256-261
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• 1973

Complex formation of magnesium-Eriochrome Black T at constant ionic strength and hydrogen ion concentration have been studied spectrophotometrically in acetonitrile solution. The measured pH values were calibrated with standard buffer solutions by using a glass electrode Ag/0.1M $AgNO_3$ reference electrode couple. The results are as follows;$E_{glass}=716+59.1\;logA_{H+}[mv]$+(in mv. vs. Ag reference electrode for picric acid $-10^{-3}M$ tetramethylammonium picrate buffer), and $E_{glass}=1,193+59.1\;logA_{H+}[mv]$(in mv. vs. Ag reference electrode for 1,3-diphenylguanidine $-3{\times}10^{-3}M $ 1,3-diphenylguanidine perchlorate buffer). The acid dissociation exponent of ligand, $ pK_{H,EBT-}$was found to be 9.1. The conditional formation constants of $MgEBT^{-}$complex by log-ratio method were 3.97 (when m = 2) and 5.02 (when m = 1) as $log K_n$, respectively, for the reaction of $H_mEBT^{(3-m)-} + Mg^{2+} {\leftrightarrow}MgEBT^{-} + mH^{+}$. The present study showed that$MgEBT^{-}$ has the composition of 1:1 which agrees with the result of Schwarzenbach et al. in aqueous solution.