• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1153-1159
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• 2013

A novel solid-contact indium(III)-selective sensor based on bis-(1H-benzimidazole-5-methoxy-2-[(4-methoxy-3, 5-dimethyl-1-pyridinyl) 2-methyl]) thiosulfinate, known as an omeprazole dimer (OD) and a neutral ionophore, was constructed, and its performance characteristics were evaluated. The sensor was prepared by applying a membrane cocktail containing the ionophore to a graphite rod pre-coated with polyethylene dioxythiophene (PEDOT) conducting polymer as the ion-to-electron transducer. The membrane contained 3.6% OD, 2.3% oleic acid (OA) and 62% dioctyl phthalate (DOP) as the solvent mediator in PVC and produced a good potentiometric response to indium(III) ions with a Nernstian slope of 19.09 mV/decade. The constructed sensor possessed a linear concentration range from $3{\times}10^{-7}$ to $1{\times}10^{-2}$ M and a lower detection limit (LDL) of $1{\times}10^{-7}$ M indium(III) over a pH range of 4.0-7.0. It also displayed a fast response time and good selectivity for indium(III) over several other ions. The sensor can be used for longer than three months without any considerable divergence in potential. The sensor was utilized for direct and flow injection potentiometric (FIP) determination of indium(III) in alloys. The parameters that control the flow injection method were optimized. Indium(III) was quantitatively recovered, and the results agreed with those obtained using atomic absorption spectrophotometry, as confirmed by the f and t values. The sensor was also utilized as an indicator electrode for the potentiometric titration of fluoride in the presence of chloride, bromide, iodide and thiocyanate ions using indium(III) nitrate as the titrant.

• Corrosion Science and Technology
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• v.14 no.5
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• pp.239-246
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• 2015

Stainless steel is generally known to have characteristics of excellent corrosion resistance and durability, but in a marine environment it can suffer from localized corrosion due to the breakdown of passivity film due to chloride ion in seawater. Furthermore, the damage behaviors are sped up under a cavitation environment because of complex damage from electrochemical corrosion and cavitation-erosion. In this study the characteristics of electrochemical corrosion and cavitation erosion behavior were evaluated on 16.7Cr-10Ni-2Mo stainless steel under a cavitation environment in natural seawater. The electrochemical experiments have been conducted at both static conditions and dynamic conditions inducing cavitation with different current density parameters. The surface morphology and damage behaviors were compared after the experiment. After the cavitation test with time variables morphological examinations on damaged specimens were analyzed by using a scanning electron microscope and a 3D microscope. the galvanostatic experiment gave a cleaner surface morphology presented with less damage depth at high current density regions. It is due to the effect of water cavitation peening under the cavitation condition. In the cavitation experiment, with amplitude of $30{\mu}m$ and seawater temperature of $25^{\circ}C$, weight loss and cavitation-erosion damage depth were dramatically increased after 5 hours inducing cavitation.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.942-952
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• 2013

Monoliths are functional porous materials with a three-dimensional continuous interconnected pore structure in a single piece. A monolith with uniform shape based on poly(${\gamma}$-glutamic acid) (PGA) has been prepared via a thermally induced phase separation technique using a mixture of dimethyl sulfoxide, water, and ethanol as solvent. The morphology of the obtained monolith was observed by scanning electron microscopy and the surface area of the monolith was evaluated by the Brunauer Emmett Teller method. The effects of fabrication parameters such as the concentration and molecular mass of PGA and the solvent composition have been systematically investigated. The PGA monolith was cross-linked with hexamethylene diisocyanate to produce the water-insoluble monolith. The addition of sodium chloride to the phase separation solvent affected the properties of the cross-linked monolith. The swelling ratio of the cross-linked monolith toward aqueous solutions depended on the buffer pH as well as the monolith fabrication condition. Copper(II) ion was efficiently adsorbed on the cross-linked PGA monolith, and the obtained copper-immobilized monolith showed strong antibacterial activity for Escherichia coli. By combination of the characteristic properties of PGA (e.g., high biocompatibility and biodegradability) and the unique features of monoliths (e.g., through-pore structure, large surface area, and high porosity with small pore size), the PGA monolith possesses large potentials for various industrial applications in the biomedical, environmental, analytical, and separation fields.

• Journal of the Korean Applied Science and Technology
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• v.31 no.1
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• pp.92-100
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• 2014

Hydrophobic magnesium hydroxide [$Mg(OH)_2$] was modified by hydrothermal method using non-ionic sorbitol surfactant with Span series. Mganesium chloride [$MgCl_2$] and sodium hydroxide [NaOH] were used for synthesis of $Mg(OH)_2$. Also non-ionic surfactant were added as a stabilizer, dispersant and surface modifier. Addition of non-ionic surfactant was favourable to obtain small sized $Mg(OH)_2$ particles with better dispersibility and hydrophobic property of $Mg(OH)_2$ particles. The obtained product were characterized by particle size analysis(PSA), scanning electron microscope(SEM), energy dispersive spectroscopy(EDS), x-ray diffraction(XRD) and fourier transform infrared spectroscopy(FT-IR). The results show that the product are prepared with this method has a well hydrophobic properties and dispersity compared with unmodified $Mg(OH)_2$ particles. The improve properties of surface modified $Mg(OH)_2$ particles were also verified by similarity synthesizing under slightly different conditions.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.4
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• pp.314-324
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• 2016

To improve the color stability of chlorophyll in young barley leaf used as functional green biomaterial, the absorption spectrum, color values, and antioxidative activities of young barley leaf (YBL) treated with zinc ion solutions were investigated. The small pieces of fresh YBL in aqueous solution mixtures were autoclaved twice at $110^{\circ}C$ for 30 min (pH 5). Distilled water (BLA), 0.01% zinc chloride (BLAZ), 0.01% zinc citrate (BLAC), and 0.01% zinc lactate (BLAL) solutions were used. Treated YBL powders were extracted with 80% EtOH for 4 h. Chlorophyll a and b contents differed with different treatments. BLA decreased chlorophyll a and b contents, whereas others were maintained. Absorbance spectrums of chlorophyll at 400~700 nm showed different maximum peak wavelengths. After heating in acidic and neutral solutions (pH 3, 5, and 7), the colors of YBL and BLA changed from green to olive green, whereas BLAZ, BLAC, and BLAL remained green color. The antioxidative activities showed higher values in YBL extract than in treated extracts. From the above results, autoclaved YBL in zinc solution would increase the color stability and maintain green color regardless of acid and heat treatments.

• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.109-114
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• 2003

The electronic absorption spectra of trans-$[CrX_2([15]aneN_4)]ClO_4\;([15]aneN_4$=1,4,8,12-tetraazacyclopentadecane; X=F, Cl) complexes have been interpreted using the ligand field theory. An AOMX program is used to optimize the differences between the calculated and the observed positions for the spin-allowed transition bands. The crystal field theory(CFT) parameter is directly related to the angular overlap model(AOM), normalized spherical harmonic hamiltonians(NSH), and semiempirical parameters. The various ligand field parameters are discussed in terms of their chemical significances. According to the ligand field analysis, we can confirm that the fluoride ligand is a very strong ${\sigma}-$ and ${\pi}-$donor while the chloride has weak ${\sigma}-$ and ${\pi}-$donor properties toward chromium(III) ion.

• Resources Recycling
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• v.16 no.6
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• pp.20-27
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• 2007

This paper presents a detailed experimental study on the durability properties of mortar matrix made with two kind of recycled fine aggregates(RAA, RAB) and five replacement levels (0, 25, 40, 75 and 100) of the recycled fine aggregates as a partial replacement of natural fine aggregate (NA). The durability properties of mortar matrix was evaluated using compressive strength, chloride ion ingress, sulfate attack and carbonation. The test results indicated that the water absorption and Adhered mortar of the recycled fine aggregate was a major factor controlling durability properties. Hereafter, when using built recycled fine aggregate is expected, appropriate removal Adhered mortar and reasonable replacement ratio of recycled fine aggregates was 25% weight of cement are advised to apply to the concrete materials.

• Journal of the Korea Institute of Building Construction
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• v.8 no.3
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• pp.93-99
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• 2008

The purpose of this study is to evaluate the bond strength and corrosion resistance of coated reinforcing bar using hybrid-type polymer cement slurry(PCS). PCS coated steels, which is made from two types of polymer dispersions such as St/BA and EVA are prepared, and tested for bond strength and various corrosion resistances such as autoclaved cure, carbonation and H2SO4 solution. From the test results, the bond strength of PCS coated reinforcing bar using ordinary portland cement at 1-5, 2-1 and 4-5 of mixes is higher than that of uncoated regular steel. However, bond strength of almost PCS coated reinforcing bars using ultra rapid high strength cement is higher than that of epoxy coated bar, is also in ranges of 102% to 123% compared to that of uncoated regular steel. In autoclaved accelerating test, the ratio of corrosion of uncoated regular steel is increased with the increase in NaCl content, but the corrosion of PCS coated steel was very small. In the acceleration test for carbonation, increasing the amount of NaCl the corrosion of coated steel did not produce. The corrosion of uncoated regular steel is increased with the increase in the amount of NaCl. It can be seen that the NaCl following the acceleration test for carbonation can lower the corrosion resistance of concrete. As a result, the corrosion of steel largely is affected by the acceleration curing, chloride ion penetration and carbonation and shown more severe corrosion by applying complex factors. These corrosions of steel can be suppressed by the coating of PCS.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2707-2712
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• 2009

5-$HT_{3}$ receptor;5-$HT_{3A}$ receptor channel activity;Novel 5-$HT_{3}$ receptor channel current blockers;Chlorophenyl substituted piperazinylethylaminomethylpyrazoles; The 5-$HT_{3A}$ receptors are one of ligand-gated ion channels and are known to be involved in visceral pain, anxiety, or anticancer agent-induced nausea and vomiting. In present study, we designed novel skeletons based on the developed 5-$HT_{3}$ receptor antagonists and evaluated their effects on 5-$HT_{3A}$ receptor channel currents ($I_{5-HT}$) of a series of pyrazole derivatives having N-chlorophenylpiperazine functionality (6-9). We found that most of N-p-chlorophenyl substituted piperazinyl-pyrazole derivatives (7b, 7c, 7e and 7h) exhibited the high potency for the inhibition of $I_{5-HT}$, whereas the compound without chloride (6) or with m-chlorophenyl group (a serious of 8 and 9) showed the low potency. These result indicate that p-chlorophenyl group is might play an important role for increasing the inhibitory potency on $I_{5-HT}$.

• Polymer(Korea)
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• v.33 no.4
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• pp.342-346
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• 2009

The effects of the monomer ratios on the typical properties of polymer modified mortars that contain styrene and butyl acrylate latexes was investigated. Basic data was also obtained that is necessary for the development of appropriate latexes for cement modifiers. Polymer modified mortars that contain styrene and butyl acrylate latexes polymerized with various monomer ratios were prepared for different polymer-cement ratios. They were then tested to obtain the particle size of the polymer latexes, air contents, water-cement ratios, flexural and compressive strengths, water absorption, and chloride-ion penetration. From the test results, the polymer modified mortars that have styrene and butyl acrylate latexes (with the mix proportions of synthesis having monomer ratios of between 40:60 to 60:40 for the appropriate mix proportions) could be recommended for practical applications. The basic properties of the polymer modified mortars were more affected by the polymer-cement ratio than by the monomer ratio, and were improved over unmodified mortar.