• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.4
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• pp.497-504
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• 2022

The purpose of this study is to evaluate the antibacterial effects of two liquid fluoride materials on Streptococcus mutans (S. mutans). Riva star aqua^TM (SDI, Bayswater, Australia), which consists of silver fluoride (AgF, step 1) and potassium iodide (KI, step 2), and Fluor protector^® (FP; Ivoclar Vivadent, Liechtenstein) were used for experimental groups. Experimental groups were divided into 4 groups : AgF, KI, AgF + KI and FP. For the positive control (PC) group, ampicillin was used, and the negative control group (NC) did not receive any additional treatment. Each group was divided into 30 and 50 µL groups by volume of liquid and applied to flat-coated S. mutans. The diameter of the zone of inhibition was measured. The PC and AgF groups showed larger diameters than other materials (p < 0.05), and the AgF group showed no significant difference from the PC group in the 50 µL group (p > 0.05). The FP group showed larger diameters than the AgF + KI group in the 30 µL (p = 0.009). The KI group did not show significant difference from the NC group (p > 0.05). AgF is comparable to ampicillin in antibacterial effects on S. mutans, and better than FP.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1329-1334
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• 2006

The electrochemical reduction of coumarin, 7-acetoxy-4-methyl coumarin (AMC), and 7-acetoxy-4-bromomethyl coumarin (ABMC), in 0.1 M tetraethyl ammonium perchlorate/acetonitrile solution was carried out by direct current, differential pulse polarography, cyclic voltammetry, and controlled potential coulometry. The electrochemical reduction of ABMC was proceeded through three steps of electron transfer coupled with the chemical reactions. The color of solution was changed to yellow when the carbonyl group was reduced during 2nd step (-1.8 volts) and independented with cleavage of bromo group. Highest fluorescence intensity showed when the electrochemical reduction of AMC was controlled at near the potential (-2.3 volts vs. Ag/AgCl).

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.187-187
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• 2015

The past thirty years have seen increasingly rapid advances in the field of Indium Tin Oxide (ITO) transparent thin film.[1] However, a major problem with this ITO thin film application is high cost compared with other transparent thin film materials.[2] So far, in order to overcome this disadvantage, we show a transparent ITO/Ag/i-ZnO multilayer thin film electrode can be the solution. In comparison with using amount of ITO as a transparent conducting material, intrinsic-Zinc-Oxide (i-ZnO) based on ITO/Ag/i-ZnO multilayer thin film showed cost-effective and it has not only highly transparent but also conductive properties. The aim of this research has therefore been to try and establish how ITO/Ag/i-ZnO multilayer thin film would be more effective than ITO thin film. Herein, we report ITO/Ag/i-ZnO multilayer thin film properties by using optical spectroscopic method and measuring sheet resistance. At a certain total thickness of thin film, sheet resistance of ITO/Ag/i-ZnO multilayer was drastically decreased than ITO layer approximately $40{\Omega}/{\square}$ at same visible light transmittance.(minimal point $5.2{\Omega}/{\square}$). Tendency, which shows lowly sheet resistive in a certain transmittance, has been observed, hence, it should be suitable for transparent electrode device.

• Resources Recycling
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• v.15 no.5 s.73
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• pp.33-37
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• 2006

An equal-molar mixture of silver chloride (AgCl) and copper (Cu) was ground in atmosphere conditions using a planetary ball mill to investigate mechanochemical (MC) reaction for preparation of silver powders. The reaction causes the mixture of AgCl and Cu to change the composition of the mixture, such as silver (Ag) and cuprous chloride (CuCl). Through the leaching with ammonium hydroxide solution (1 mol), CuCl can be separated from MC product, so that pure Ag powders can be obtained as the final product. Moreover, polyvinylpyrrolidone (PVP) was used as the additive not only to improve dispersion of Ag pow- der during MC process, but also to control surface oxidation of Ag powders, prepared as the final product.

• Journal of Welding and Joining
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• v.25 no.3
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• pp.57-63
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• 2007

Electrochemical migration characteristics of Pb-free solder alloys are quantitatively correlated with corrosion characteristics in harsh environment conditions. In-situ water drop test and corrosion resistance test for Sn-3.0Ag-0.5Cu solder alloys were carried out in NaBr and NaF solutions to obtain the electrochemical migration lifetime and pitting potential, respectively. Sn-3.0Ag-0.5Cu solder alloy shows similar ionization and electrochemical migration behavior with pure Sn because of Ag and Cu do not migrate due to the formation of resistant intermetallic compounds inside solder itself. Electrochemical migration lifetime in NaBr is longer than in NaF, which seems to be closely related to higher pitting potential in NaBr than NaF solution. Therefore, it was revealed that electrochemical migration lifetime of Sn-3.0Ag-0.5Cu solder alloys showed good correlation to the corrosion resistance, and also the initial ionization step at anode side is believed to be the rate-determining step during electrochemical migration of Pb-free solders in these environments.

• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.25-33
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• 2015

In this study, Fe₃O₄-ACCS-Ag nanoparticles (NPs) were successfully synthesized using silica extracted from corn cob ash. The synthesized Fe₃O₄-ACCS-Ag NPs were characterized using X-ray diffraction (XRD), scanning electron microscopyenergy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR). In addition, the potential application of Fe₃O₄-ACCS-Ag NPs as an antibacterial material in water disinfection was investigated using Escherichia coli ATCC 8739 as model bacteria. The antibacterial activity of synthesized composite material showed 99.9% antibacterial effect within 20 min for the tested bacteria. From this experiment, the synthesized Fe₃O₄-ACCS-Ag nanocomposites also hold magnetic properties and could be easily recovered from the water solution for its reuse. The reused nanocomposites presented the decreasing antibacterial efficiencies with the reuse cycle but the composite used three times still killed 90% of bacteria in 20 min.

• KSBB Journal
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• v.17 no.1
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• pp.20-25
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• 2002

We performed a basic experiment for rapid, on-line, real-time measurement of HBsAg by using a surface plasmon resonance biosensor to quantify the recognition and interaction of biomolecules. We immobilized the anti-HBsAg polyclonal antibody to the dextran layer on a CM5 chip surface which was pre-activated by N-hydroxysuccinimide for amine coupling. The binding of the HBsAg to the immobilized antibody was measured by the mass increase detected by the change in the SPR signal. The binding characteristics between HBsAg and its antibody followed typical monolayer adsorption isotherm. When the entire immobilized antibody was interacted, there was no additional, non-specific binding observed, which suggested the biointeraction was very specific as expected and independent of the ligand density. No significant steric hindrance was observed at 17.6 nm/$mm^2$ immobilization density. The relationship between the HBsAg concentration in the sample solution and the antigen bound to the chip surface was linear up to ca. $40\mu\textrm{g}$/mL, which is much wider than that of the ELISA method. It appeared the antigen-antibody binding was increased as the immobilized ligand density increased, but verification is warranted. This study showed the potential of this biosensor-based method as a rapid, simple, multi-sample, on-line assay. Once properly validated, it can serve as a more powerful method for HBsAg quantification replacing the current ELISA method.

• Resources Recycling
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• v.25 no.5
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• pp.50-56
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• 2016

Extraction behaviour of silver from nitric acid solutions by Cyanex 301 as an extractant was examined. Detailed studies have been conducted to evaluate the effect of different variables influencing the extraction such as concentration of nitric acid and extractant, phase ratio(O/A) and synergism of mixed extractant. The extraction behaviour of associated metals namely Ca, Al, Fe, Zn and Sr has been investigated. The extraction results show that Ag can be extracted effectively by Cyanex 301 and selectively extracted from 3.0M $HNO_3$ using 5% Cyanex 301. Impurity metals loaded in organic phase can be effective scrubbed by 4.0M HCl. Finally, pure silver solution can be obtained efficiently by thiourea as a stripping reagent.

• ETRI Journal
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• v.26 no.3
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• pp.252-256
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• 2004

We formed silver nanocrystallites by the thermal decomposition of a $Ag^{+1}$-oleate complex, which was prepared by a reaction with $AgNO_{3}$ and sodium oleate in a water solution. The resulting monodispersed silver nanocrystallites were produced by controlling the temperature (290$^{\circ}$C). Transmission electron microscopic (TEM) images of the particles showed a 2-dimensional assembly of the particles with a diameter of $9.5{\pm}0.7nm$, demonstrating the uniformity of these nanocrystallites. An energy-dispersive X-ray (EDX) spectrum and X-ray diffraction (XRD) peaks of the nanocrystallites showed the highly crystalline nature of the silver structure. We analyzed the decomposition of the $Ag^{+1}$-oleate complex using a Thermo Gravimetric Analyzer (TGA) and observed the crystallization process using XRD.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.149-152
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• 2002

SrZrO3 resistive oxide barriers on Ag sheathed Bi2223 tapes prepared by the sol-gel and dip coating method were evaluated with an aid of Taguchi method and orthogonal arrays to elucidate the effects of experimental parameters, such as ratio of starting solution, amount of additives, and heat treatment temperature and time on the properties of the thin films. Six experimental parameters were selected and then Ll8(21x37) orthogonal arrays were constructed. Finally, SEM and XRD results were related to signal to noise (S/N) ratio to evaluate the optimized experimental condition.