• Bulletin of the Korean Chemical Society
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• v.3 no.3
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• pp.83-88
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• 1982

Viscosity and zeta-potential of 11.0 wt. % aqueous bentonite suspension containing various electrolytes and hydrogen-ion concentration were measured by using a Couette type automatic rotational viscometer and Zeta Meter, respectively. The effects of pH and elcctrolytes on the rheological properties of the suspension were investigated. A system, which has a large zeta-potcntial, has a small intrinsic relaxation time ${\beta}$ and a small intrinsic shear modulus $1/{\alpha}$ in the Ree-Eyring generalized viscosity equation, i.e., such a system has a small viscosity value, since ${\eta}={\beta}/{\alpha}$. In general, a stable suspension system has large zeta-potential. The stability condition of clay-water suspension can be estimated by viscometric method since stable suspension generally has small viscosity. The correlation between the stability, viscosity and zeta-potential has been explained by the Ree-Eyring theory of viscous flow.

• Bulletin of the Korean Chemical Society
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• v.7 no.6
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• pp.462-465
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• 1986

Kinetics and Mechanism of $N_2H_4-KBrO_3$ reaction in the presence of allyl alcohol have been studied. The pseudo-first order rate constant for gas evolution was found to be $10^{-4}{\sim}10^{-2}\;sec^{-1}\;at\;25.0{\pm}0.1^{\circ}C$, increasing with concentration of hydrogen ion. When concentrations of sulfuric acid and allyl alcohol are both sufficiently high, the following overall reaction explains experimental results reasonably well: $N_2H_4\;+\;BrO_3^-\;+\;H^+\;{\to}\;N_2\;+\;HOBr\;+\;2H_2O,\;CH_2\;=\;CHCH_2OH\;+\;HOBr\;{\to}\;CH_2-OHCHBrCH_2OH$. More complicated reaction mechanisms at lower acidity conditions have been contemplated.

• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.510-515
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• 1985

Color of $MoO_{(aq)}^{3+}$ in concentrated methanesulfonic acid (∼10M) changes dark green due to the formation of $Mo_2O_2(OH)_{2(aq)}^{4+}$ dimer. This color is similar to that shown by addition of water to that shown by addition of water to green $MoO_{(aq)}^{3+}$ solution in 15-16M methanesulfonic acid. The molar extinction coefficient of monomer in 15M methanesulfonic acid is about 20 at 415nm. Rate constants are independent on the aquomolybdenum (V) and hydrogen ion concentration under the condition of this experment. Bridging hydroxides of $Mo_2O_2(OH)_{2(aq)}^{4+}$ are dehydrogenated at the less concentration of ∼6 M for HPTS and ∼10M for $CH_3SO_3H$. The structure of both the yl-oxygens and the bridging oxygens of final product is identified to (*image)unit.

• Molecules and Cells
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• v.37 no.2
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• pp.100-108
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• 2014

Salmonella enterica serovar Typhimurium (S. Typhimurium) is an intracellular pathogen that has evolved to survive in the phagosome of macrophages. The periplasmic copper-binding protein CueP was initially known to confer copper resistance to S. Typhimurium. Crystal structure and biochemical studies on CueP revealed a putative copper binding site surrounded by the conserved cysteine and histidine residues. A recent study reported that CueP supplies copper ions to periplasmic Cu,Zn-superoxide dismutase (SodCII) at a low copper concentration and thus enables the sustained SodCII activity in the periplasm. In this study, we investigated the role of CueP in copper resistance at a high copper concentration. We observed that the survival of a cueP-deleted strain of Salmonella in macrophage phagosome was significantly reduced. Subsequent biochemical experiments revealed that CueP specifically mediates the reduction of copper ion using electrons released during the formation of the disulfide bond. We observed that the copper ion-mediated Fenton reaction in the presence of hydrogen peroxide was blocked by CueP. This study provides insight into how CueP confers copper resistance to S. Typhimurium in copper-rich environments such as the phagosome of macrophages.

• Korean Journal of Microbiology
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• v.20 no.3
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• pp.119-124
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• 1982

As a basic study to elucidate nutritional physiology and composition of synthetic medium of red rotting bacteria, Erwinia carotovora, of ginseng, the effects of hydrogen ion concentration, various kinds of carbon sources, nitrogen source, micrometallic salts and it's concentration on the gorwth of the bacteria were investigated and the results were as follows. Optimal pH in the basal medium for the growth of the bacteria was 6.5. After incubation the pH in culture media was neutralized. Among the various kinds of carbon sources, sucrose, glucose mannitol, but organic acids were not utilized effectively as nutrients. After incubation the pH turned acidic. Alanine as organic nitrogen sources nad ammonium sulfate as inorganic nitrogen promoted the growth, but L-valine and sodium nitrite were the least effective. Ferric chloride 1.0mg/dl and ferrous sulfate 100mg/dl were the most effective as micrometallic sources. Control and boric acid were the least effective. New synthetic medium based on the above results was follows ; Alanine 1.0g, $KH_2PO_4\;1.0g, \;sucrose\;30.0g, \;MgSo_4{\cdot}7H_2O\;0.5g, \;FeCl_3{\cdot}6H_2O\;1.0mg\;thiamine\;200{\gamma}g$, and distilled water 1000ml, pH6.5.

• Applied Chemistry for Engineering
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• v.5 no.1
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• pp.149-159
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• 1994

The kinetics and equilibrium of metal extraction by benzamidoxime and phenylacetamidoxime-chloroform were investigated to apply amidoxime to metal extraction as chelating agent. The overall extraction constant extraction mechanism and selective extraction of copper were examined from the relation among extraction ratio, hydrogen ion concentration and extractant concentration. The experimental rate equation of copper extraction coincided with the theoretical rate equation and was expressed as $R_o=k{\overline{C}}_{HRo}(C_{Mo}/C_{Ho})^{1/2}$. The chemical species extracted was found to the type of ${\overline{CuR_2}}$.

• Korean Journal of Animal Reproduction
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• v.3 no.1
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• pp.41-47
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• 1979

This experiment was carried out to clarify the methods of the F-body test in human and the B-body test in buil and hog. The effect of pH and albumin concentration on the migration of X- and Y- sperm was also investigated. The results obtained were summarized as follows: 1. In the human semen, the frequency of sperm in which an F-body is visible was different by the fluorochrome. Namely, in case of quinacrine mustard, the F-body frequency was 48.8∼43.4 percent (average 49.6%), and in case of quinacrine dihydrochloride, that was 40.7∼50.8 percent (average 42.0%). 2. The frequency of a, pp.rance of B-body was 43.4${\pm}$1.3 percent in bull semen, and 45.5${\pm}$0.7 percent in hog semen. 3. A, pp.arance of B-body in bovine semen was increased due to duration of time after washing till 12 hours. 4. Separation of X- and Y- spermatozoa using diluents with different hydrogen ion concentration was impossible. 5. A, pp.arance of B-body separated in medium with 6, 10 and 20% ovalbumin was 51.1${\pm}$2.4, 50.6${\pm}$2.5 and 58.2${\pm}$3.0 percent, respectively, and those values were significiantly higher (p<0.01) than corresponding control values.

• Korean Journal of Microbiology
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• v.13 no.1
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• pp.37-44
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• 1975

As a basic study to elucidate nutritional physiology and composition of synthetic medium of red rotting bacteria, Erwinia carotovora, of ginseng, the effects of hydrogen ion concentration, various kinds of carbon sources, nitrogen source, micrometallic salts and it's concentration on the gorwth of the bacteria were investigated and the results were as follows. Optimal pH in the basal medium for the growth of the bacteria was 6.5. After incubation the pH in culture media was neutralized. Among the various kinds of carbon sources, sucrose, glucose mannitol, but organic acids were not utilized effectively as nutrients. After incubation the pH turned acidic. Alanine as organic nitrogen sources nad ammonium sulfate as inorganic nitrogen promoted the growth, but L-valine and sodium nitrite were the least effective. Ferric chloride 1.0mg/dl and ferrous sulfate 100mg/dl were the most effective as micrometallic sources. Control and boric acid were the least effective. New synthetic medium based on the above results was follows ; Alanine 1.0g, $KH_2PO_4$ 1.0g, sucrose 30.0g, $MgSo_4$ $7H_2$O 0.5g, $FeCl_36H_2$O 1.0mg thiamine 200.gamma.g, and distilled water 1000ml, pH6.5.

• Journal of Korean Society on Water Environment
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• v.21 no.3
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• pp.284-288
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• 2005

In this study, photochemical advanced oxidation processes (AOPs) utilizing the Photo Fenton reaction ($Fe^{2+}+H_2O_2+UV$) were investigated in lab-scale experiments for the treatment of livestock wastewater. For the experimets, the livestock wastewater was pretreated by coagulation with $3,000mg/L\;FeCl_3$. The optimal conditions for Photo-Fenton processes were determined: pH was 5, the concentration of ferrous ion (Fe II) was 0.01 M. The concentration of hydrogen peroxide was 0.1 M, and molar ratio ($Fe^{2+}/H_2O_2$) was 0.1. The optimal reaction time was 80 min. Under the optimal condition of Photo-Fenton process, chemical oxygen demand (COD), color and fecal coliform removal efficiencies were about 79, 70, and 99.4%, respectively and sludge production was 7.5 mL from 100 mL of solution.

• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.416-424
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• 2018

Microstructure of oxide formed on Zr-Nb-Sn tube sample was intensively examined by scanning transmission electron microscopy after exposure to simulated primary water chemistry conditions of various concentrations of Zn (0 or 30 ppb) and dissolved hydrogen ($H_2$) (30 or 50 cc/kg) for various durations without applying desirable heat flux. Microstructural analysis indicated that there was no noticeable change in the microstructure of the oxide corresponding to water chemistry changes within the test duration of 100 days (pretransition stage) and no significant difference in the overall thickness of the oxide layer. Equiaxed grains with nano-size pores along the grain boundaries and microcracks were dominant near the water/oxide interface, regardless of water chemistry conditions. As the metal/oxide interface was approached, the number of pores tended to decrease. However, there was no significant effect of $H_2$ concentration between 30 cc/kg and 50 cc/kg on the corrosion of the oxide after free immersion in water at $360^{\circ}C$. The adsorption of Zn on the cladding surface was observed by X-ray photoelectron spectroscopy and detected as ZnO on the outer oxide surface. From the perspective of $OH^-$ ion diffusion and porosity formation, the absence of noticeable effects was discussed further.