• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.698-704
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• 1995

The ion-selective membrane fabricated with 33 wt% PVC, 66 wt% o-NPOE and 1 wt% 4'-benzothiazolylbenzo-15-crown-5 (TB15C5) as a neutral carrier exhibited an enhanced selectivity to potassium ion over sodium ion compared to those prepared with other 15-crown-5 or 18-crown-6 derivatives. The potentiometric properties (response slope, selectivity, detection limits and lifetime) of TB15C5-based ISE membranes along with those based on valinomycin, benzo-15-crown-5 (B15C5), 4'-aminobenzo-15-crouwn-5 (AB15C5), benzo-18-crown-6 (B18C6), dibenzo-18-crown-6 (DB18C6) and bis[(benzo-15-crown-5)-4'-ylmethyl]pimelate (PI-Ⅱ) ionophores were carefully examined under the same experimental conditions. The enhanced selectivity of TB15C5-based membrane to potassium is explained in terms of the effect of the benzothiazol functional group and the distribution coefficients of metal ions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.123-131
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• 2004

The effect of reactive oxygen species (ROS) on the formation of $N^{\varepsilon}$-(carboxymethly)lysine (CML). one of the endproducts in the Maillard reaction of protein (or glycation), was investigated. Glyoxal, a main precursor of CML formation, was produced from both glucose and fructose during their autoxidation. The transition metal ion showed to involve in the formation of glyoxal by the metal catalyzed oxidation, suggesting that ROS accelerated the reducing sugar autoxidation. The stimulative effect of ROS on the autoxidation was more prominent in glucose than in fructose. Polyunsaturated acids (PUFAs) were shown to form glyoxal by peroxidation in proportion to the degree of unsaturation, but ROS did not affect on PUFA peroxidation. Ascorbic acid also lysine (CMHL) in the model system using hippuryl lysine and glucose had a significant effect on ROS, whereas it had no effect on ROS using glyoxal as a reactant. Almost the same trend was obtained by the analysis of antigen coated indirect noncompetitive ELISA using monoclonal antibody (6D12). These data indicated that ROS affected glucose autoxidation as well as mediated both CML and glyoxal formation, but did not affect the reactive compounds such as fructose, PUFAs and ascorbic acid.

• Analytical Science and Technology
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• v.9 no.3
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• pp.279-291
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• 1996

The new chelating resins, XAD-2, 4, 16-TAC and XAD-2, 4, 16-TAO were synthesized by Amberlite XAD-2, XAD-4, and XAD-16 macroreticular resins with 2-(2-thiazolylazo)-p-cresol(TAC) and 4-(2-thiazolylazo)orcinol(TAO) as functional groups and were characterized by elemental analysis and FT-IR spectrometry. It was found that the content of functional group in chelating resin was 0.60mmol/g in XAD-16-TAC and 0.68mmol/g in XAD-16-TAO respectively. The chelating resins were stable in acidic and alkaline solution and can be reused over 10 times. The sorption behavior of some metalions to two chelating resins was investigated by batch method, which included batch equilibrium, effect of pH, coexisting ions and masking agent. For the optimum condition of sorption, the time required for equilibrium was about 1 hour and optimum pH was 5. In the presence of anions such as ${SO_4}^{2-}$ and $CH_3COO^-$, the sorption of U(VI) ion was slightly reduced but other anions such as $Cl^-$ and $NO{_3}^-$ revealed no interference effect. Also, sorption capacity of U(VI) ion was decreased by addition of $CO{_3}^{2-}$ ion because of complex formation of $[UO_2(CO_3)_3]^{4-}$, but alkali metals and alkali earth metals including Na(I), K(I), Mg(II), and Ca(II) were not affected for the sorption extent. Masking agent, NTA showed better separation efficiency of U(VI) ion from coexisting metal ions such as Th(IV), Zr(IV), Hf(IV), Cu(II), Cd(II), Pb(II), Ni(II), Zn(II) and Mn(II) than EDTA, CDTA.

• YAKHAK HOEJI
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• v.41 no.2
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• pp.225-232
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• 1997

The in vitro antibacterial activity of DWP20367 (1-Cyclopropyl-6-fluoro-8-chloro-7-(2,7-diazabicyclo[3,3,0]oct-4-ene-7-yl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid), a new broad-spectrum fluoroquinolone, was compared with those of ciprofloxacin (CPFX), sparfloxacin (SPFX) and ofloxacin (OFLX). DWP20367 was showed antibacterial activity much higher than CPFX, SPFX and OFLK against gram-positive bacteria, while it was slightly more superior to quinolones against gram-negative bacteria. DWP20367 was particularly effective against MRSA, and its $MlC_{90}$ against clinical isolates of methicillin-susceptible S. aureus, low methicillin-resistant S. aureus and high methicillin-resistant S. aureus were 0.098, 0.781 and 1.563 micro g/ml, respectively. Against S. pneumoniae, MIC90 of DWP20367 was 2- to 8-fold higher than those of CPFX. With a view of MIC90, DWP20367 showed slightly more potent activity against P. aeruginosa and E. coli isolates than the control quinolones. DWP20367 activity was not affected by inoculum size and medium pH. But addition of $Mg^{2+}, \;Ca^{2+} $Mg2+, Ca2+ or horse serum (25%) decreased its antibacterial activity. DWP20367 was showed rapidly bactericidal activity within 2 to 4 h, and regrowth was not observed even after 24 h incubation at concentrations near the 4-fold of MIC.

• YAKHAK HOEJI
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• v.41 no.2
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• pp.233-240
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• 1997

The in vitro antibacterial activity of DWP20418 (1R, 5S, 6S)-6-[1-(R)-Hydroxyethyl)-l-methyl-2-[(2S,4S)-2-(piperazinylcarbonyl)-1-(R)-hydroxyethyl)pyrrolidine-4-thio]carb apen-2-em-3-carboxylic acid), a new carbapenem antibiotic, was compared with those of imipenem (IPM) and meropenem (MEPM). DWP20418 was comparable or slightly more superior to MEPM against gram-positive bacteria, and it showed more potent activity to IPM against gram-negative bacteria. DWP20418 was particularly active against MRSA, and its $MIC_{90}$ of methicillin-susceptible S. aureus, low methicillin-resistant S. aureus and high methicillin-resistant S. aureus were 0.391, 25 and 50 ${\mu}g/ml$, respectively. With a view of $MIC_{90}$, DWP20418 was comparable than the other carbapenems against P. aeruginosa and E. coli isolates. The activity of DWP20418 was not affected in the presence of $Mg^{2+},\;Ca^{2+}$ or horse serum. But inoculum size and alterations in pH of medium affected its antibacterial activity. DWP20418 showed rapidly bactericidal activity within 1h, and regrowth was not observed even incubation of 24hrs at the concentrations near the MIC.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.3
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• pp.155-161
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• 1998

Retardation effect of heavy metals in soils caused by adsorption onto the surfaces of solids particles is well known phenomenon. In this study, we investigated the retardation effect on the mobility of a Zn in a sandy soil by conducting batch and column tests. The column test consisted of monitoring the concentrations of effluent versus time known as a breakthrough curve (BTC). We used NaCl and ZnCl$_2$ solutions with the concentration of 10 g/L as a tracer, and injected them respectively into the inlet boundary of the soil sample as a square pulse type, and monitored the effluent concentrations at the exit boundary under a steady state condition using an EC-meter and ICP-AES. The batch test was conducted based on the standard procedure of equilibrating fine fractions collected from the soil with various initial ZnCl$_2$ concentrations, and analysis of Zn ions in the equilibrated solutions using ICP-AES. The results of column test showed that i) the peak concentration of ZnCl$_2$analyzed by ICP was far less than that of either NaCl or bulk electrical conductivity and ⅱ) travel times of peak concentrations for two tracers were more less identical. The relatively low concentration of Zn can be explained by ion exchange between Zn and other cations, and possible precipitation of Zn in the form of Zn(OH)$_2$due to high pH range (7.0∼7.9) of the effluent. The identical result of travel times of peak concentrations indicates that the retardation effect is not present in the soil. The only way to describe the prominent decrease of Zn ion was to introduce decay or sink coefficient in the CDE model to account for irreversible decrease of Zn ions in the aqueous phase.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.465-476
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• 2021

Scale and rust generation in water pipes is a common phenomenon when cast iron water pipes have been used for a long time. A physical water treatment device is known among various means for suppressing rust in a water pipe, and a zinc ionization device for putting zinc metal into a pipe and emitting the zinc cation into water is one of such devices. This research measured the amount of zinc ion generated, which is known to exhibit an effect of inhibiting rust and scale generation in a pipe, and examined the scale and rust inhibition effect of the ionization device installed for ground or building water supply. In the case of distilled water, the concentration of zinc ion increased by circulating water in the ionization device several times, and it was verified to be hundreds of ㎍/L, and in the case of discharging ground or tap water, it was verified to be tens of ㎍/L. In addition, a verification pipe was installed to confirm the change inside the pipe before and after installation of the zinc ionization device, and the internal condition of the pipe was observed 3 months to several years after installation. It was confirmed that the corrosion area of the surface of the pipe was no longer increased by installing a corrosion inhibitor, and if the pipe was already filled with corrosion products, the amount of corrosion products gradually decreased every year after installation. The phenomenon of fewer corrosion products could be interpreted as expanding the space in the pipe due to the corrosion product as Fe₂O₃ adhered to the inner surface of the pipe and turned into a smaller black Fe₃O₄. In addition, we found that scale such as CaCO₃ together in the corrosion by-products gradually decreased with the attachment of the ionization device.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.343-344
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• 2012

It has been known since the mid 1960s that Ag can be photodissolved in chalcogenide glasses to form materials with interesting technological properties. In the 40 years since, this effect has been used in diverse applications such as the fabrication of relief images in optical elements, micro photolithographic schemes, and for direct imaging by photoinduced Ag surface deposition. ReRAM, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of a conductive filament in a solid electrolyte. Especially, Ag-doped chalcogenide glasses and thin films have become attractive materials for fundamental research of their structure, properties, and preparation. Ag-doped chalcogenide glasses have been used in the formation of solid electrolyte which is the active medium in ReRAM devices. In this paper, we investigated the nature of thin films formed by the photo-dissolution of Ag into Ge-Se glasses for use in ReRAM devices. These devices rely on ion transport in the film so produced to create electrically programmable resistance states. [1-3] We have demonstrated functionalities of Ag doped chalcogenide glasses based on their capabilities as solid electrolytes. Formation of such amorphous systems by the introduction of Ag+ ions photo-induced diffusion in thin chalcogenide films is considered. The influence of Ag+ ions is regarded in terms of diffusion kinetics and Ag saturation is related to the composition of the hosting material. Saturated Ag+ ions have been used in the formation of conductive filaments at the solid electrolyte which is the active medium in ReRAM devices. Following fabrication, the cell displays a metal-insulator-metal structure. We measured the I-V characteristics of a cell, similar results were obtained with different via sizes, due to the filamentary nature of resistance switching in ReRAM cell. As the voltage is swept from 0 V to a positive top electrode voltage, the device switches from a high resistive to a low resistive, or set. The low conducting, or reset, state can be restored by means of a negative voltage sweep where the switch-off of the device usually occurs.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.29-33
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• 1999

Transition metallic $Cr^{3+}$ ion was diffused in white sapphire {0001}, ${10\bar{1}0}$ crystal plane which were grown by the Verneuil, it enhanced and changed the physical, electrical and optical properties of sapphires. After mixing the metallic oxide and metal powder, it were used for diffusion powder. When it was used the mixing powder of metal and metallic oxide, the dopping was slowly progressed and it needed the longer duration time and higher temperature, relatively. Metallic powder was vapoured under $1{\times}10^{-4}$ torr of vacuum pressure at $2050^{\circ}C$, first step, it were kept by the diffusion condition of 6 atm of $N_{2}$ accelerating pressure at $2050~2150^{\circ}C$. Each surface density of sapphire crystal are 0.2254(c) and $0.1199\;atom/{\AA}^2(a)$. The color of the Cr-doped sapphires was changed to red. Dopping reaction was come out more deep in the plane of ${10\bar{1}0}$ than {0001}. It was speculated that the planar density was one of the factors to determine diffusion effect.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.216-223
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• 1986

Separation of optical isomers of DNS derivatized amino acids by a reversed-phase high-performance liquid chromatography has been studied by adding a complex of an optically active amino acid (L-arginine) with the metal ion (Cu(II), Zn(II), Cd(II), Ni(II)) to the mobile phase. The separations are affected by the concentrations of acetonitrile, chelate and buffer. They are also affected by the pH and the kinds of metal and buffer. A separation mechanism, which is based on steric effect of the ligand exchange reaction for the formation of ternary complexes by the D,L-DNS-amino acids and the chiral additive associated with the stationary phase, is proposed to interpret the elution behaviors of D, L-dansyl-amino acids.