• Journal of the Korean institute of surface engineering
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• v.33 no.5
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• pp.319-328
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• 2000

Silver is known to have such characteristics as low shear strength, good transfer-film forming tendency, and good corrosion resistance. Silver thin films have been prepared by ion plating of physical vapour deposition (PVD) using both argon gas pressure and bias voltage of processing condition. After the silver films were prepared, the properties in them were examined by gas pressure and bias voltage of substrate. Their morphology and crystal orientation were investigated by scanning electron microscopy (SEM) and X-ray diffractor. The properties of film were, also, studied to relate with morphology, X-ray diffraction pattern, and friction coefficient at vacuum ambient. The friction coefficient was stabilized remarkably on deposited films with increasing argon pressure for deposition. Also, the effect of increasing of the bias voltage for deposition resulted in lower friction coefficient and stability in $1.7$\times$10^{-4}$ torr. On the contrary, behavior of friction coefficient was stabilized on deposited films with decreasing the bias voltage in $1.7$\times$10^{-5}$ torr for deposition.

• Journal of Environmental Health Sciences
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• v.15 no.2
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• pp.33-40
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• 1989

Dichromate reflux method for COD analysis is one of the useful and precise way to solve the organic content of the wastewater. But the standard procedure for COD is not entirely satisfactory for sample containing appreciable amounts of inhibiting substance, especially chloride ion. Under the conditions of the established test, a big disadvantage of the method is that dichromate oxidizes chloride quantitatively to chlorine. When it is necessary to use silver sulfate as a catalyst in the COD procedure, chloride must be removed before the addition of the catalyst. Silver sulfate and mecuric sulfate forms a precipitate of AgCl and HgCl$_{2}$ separately which is not completely oxidized during the test and, therefore, cannot be corrected for. So, we evaluate and compensate the amount of chloride oxidation in the absence of chemicals during the experimental procedure. Calculation of COD is made using the following reviced formula: real COD = tested COD - 0.2277Cl.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.798-801
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• 2004

Silver nitrate colored method that measure easily penetration depth of chloride ion has been used, recently. But, characteristics of silver nitrate colored method hasn't examined well. Therefore, we are aim to examine characteristics of colored method. According to experiment results, when the colored method was applied in concrete, it is reasonable that $AgNO_3$ solution more than 0.05N concentration was sprayed. Chloride concentration difference in colored parts was about 20ppm when $AgNO_3$ of two concentration (0.05N, 0.1N) in concrete was sprayed.

• Corrosion Science and Technology
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• v.16 no.5
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• pp.227-234
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• 2017

Reference electrodes are generally implemented for the purpose of monitoring the cathodic protection potentials of buried or immersed metallic structures. In the market, many types of reference electrodes are available for this purpose, such as saturated calomel, silver/silver chloride and copper/copper sulfate. These electrodes contain a porous ceramic junction plate situated in the cylindrical body bottom to permit ionic flux between the internal electrolyte (of the reference electrode) and the external electrolyte. In this work, the copper/copper sulfate reference electrode was modified by replacing the porous ceramic junction plate for a metallic platinum wire. The main purpose of this modification was to avoid the ion copper transport from coming from the inner reference electrode solution into the surrounding electrolyte, and to mitigate the copper plating on the coupon surfaces. Lab tests were performed in order to compare the performance of the two mentioned reference electrodes. We verified that the experimental errors associated with the measurements conducted with developed reference electrode would be negligible, as the platinum surface area exposed to the surrounding electrolyte and/or to the reference electrolyte are maintained as small as possible.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.139-145
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• 2013

The electrochemical analysis of silver ion was performed using cyclic voltammetry (CV) and square-wave (SW) stripping voltammetry, and electrode cell systems were fabricated with graphite pencil electrode (GE) of working, reference and counter electrodes. Also electrolyte was the use of sea water as electrolyte solutions instead of ionic controlled solutions. The optimum analytical conditions for the cyclic and stripping parameters were determined using GE. The results approached the microgram working ranges of SW(ug/L) and CV(ug/L) Ag, and the optimum conditions were applied to frog's tissue and the food samples.

• Environmental Analysis Health and Toxicology
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• v.12 no.3_4
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• pp.15-22
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• 1997

This experiment was performed to examine the immuno-reactive characteristics of fish metal-binding protein, metallothionein (MT), and gain the practical understandings for the proposed use of fish MT as a biomarker. Liver MT induced by Cd in the silver carp was seperated and purified by gel filtration chromatography and ion exchange chromatography. The immuno-reactivity of fish MT was examined with 3 rabbit antisera. Fish MT showed little reactivity with rabbit anti-rat MT antiserum and a weak reactivity with anti-MT peptide antiserum while showed a strong reactivity with rabbit anti-fish MT antiserum. The time-course change of liver MT in the silver carp, after waterborne exposure to 1 ppm of Cd, was checked by Cd-hem method and established competitive ELISA. In both cases, the induction of liver MT showed a good increasing relationship with the exposure days. The results indicate that the fish MT can be developed as a useful biomonitoring means in the toxicological study and for the evaluation of water pollution.

• Environmental Analysis Health and Toxicology
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• v.11 no.1_2
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• pp.11-17
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• 1996

The purpose of this experiment is to estabilish the sensitive and specific ELISA (enzyme linked immunosorbent assay) system for the detection of fish metallothionein (MT). Silver carp were injected with CA of 1-8mg/kg body wt. 4 times during 10 days. Silver carp was very tolerant species to CA. Cd induced MT in liver was seperated and purified by gel filtration chromatography and ion exchange chromatography and identified by spectrophotometry, native gel electrophoresis and western blot analysis. The rabbit antiserum was produced by immunizing rabbit with lyophilized MT, and the competitive ELISA system was estabilished for the detection of fish MT. In the present ELISA system, the detection limit was about 33 ng/ml. When this ELISA system was employed to determine the MT level in the supernatant sample of fish liver homogenate, the reaction curve showed a good parallel corelationship with the calibration curve over a certain dilution range. The results indicate that the competitive ELISA can be a useful tool for the detection of fish MT in the toxicological study and the evaluation of water pollution.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.78-81
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• 2004

Here the effect of various amino acids on the separation performance for these two contrastive membranes is investigated. It was especially focused on the structures of amino acids, and their effects on the silver ion activity as well as the interaction between polymer electrolytes and amino acid. The amino acids studied include asparagine, valine, glutamic acid and lysine.(omitted)

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.233-242
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• 2020

As studies and developments of nano-material increase, the release of the nano-sized material to water environment increase. Especially, silver nanoparticles have been found as dissolved and particulate state since nano-silver particle have been intensively used in industrial and our living environment due to the anti-bacterial effect of the nano-particles. The silver nano-particles and silver ion gives adverse effect on ecology and US-EPA set a secondary drinking water standards as 0.1 mg/L. Current study focused on the analysis of silver in groundwater, small scale water supply systems in Gyeongbook area. The results have been compared with the secondary drinking water standards and discussed at the point of characteristics of the local area and purpose of use of the water sample. Among the total of 298 samples, 2 samples exceed the secondary drinking water standards of EPA, 0.64% rate. Community drinking water and simplified water service showed relatively high detection rate and groundwater gave relatively higher concentration of silver indicating anthropogenic source and natural source could contribute simultaneously on groundwater.

• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.35-42
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• 2000

Reaction characteristics of 4-methylcatechol 2,3-dioxygenase (4MC230) purified from Pseudomonas putida SU10 with a higher activity toward 4-methylcatechol than catechol or 3-cethylcatechol were studied by altering their physical and chemical properties. The enzyme exhibited a maximum activity at pH 7.5 and approximately 40% at pH 6.0 for 4-methylcatechol hydrolysis. The optimum temperature for the enzyme was around $35^{\circ}C$, since the enzyme was unstable at higher temperature. Acetone(10%) stabilized the 4MC230. The effects of solvent and other chemicals (inactivator or reactivator) for the reactivation of the 4MC230 were also investigated. Silver nitrate and hydrogen peroxid severely deactivated the enzyme and the deactivation by hydrogen peroxide severely deactivated the enzyme and the deactivation by hydrogen peroxide was mainly due to the oxidation of ferrous ion to ferric ion. Some solvents acted as an activator and protector for the enzyme from deactivation by hydrogen peroxide. Ascorbate, cysteine, or ferrous ion reactivated the deactivated enzyme by hydrogen peroxide. The addition of ferrous ion together with a reducing agent fully recovered the enzyme activity and increased its activity abut 2 times.