• Analytical Science and Technology
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• v.8 no.4
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• pp.617-622
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• 1995

Electrocatalytic reduction of dioxygen has been investigated by cyclic voltammetry at glassy carbon electrode modified with new Co(II)-Schiff base complexes in aqueous solutions of various pH. The reduction potentials of dioxygen at chemically adsorbed electrodes show the dependence of pH between pH 4 and 14. The catalytic effect is large and the reaction occurs via two or four electron transfer in various pH solution.

• The Korean Journal of Food And Nutrition
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• v.12 no.2
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• pp.204-208
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• 1999

In order to obtain data for use of algin in drink making process solution properties of algin have been investigated at various condition of algin concentration temperature pH and various food additives. At same revolution velosity viscosities of algin were increased as algin concentration raised. Algin solution showed dilatnat type flow in concentration of 0.25% to 0.4% but pseudoplastic type flow in above 0.5% showed dilatant type flow in concentration of 0.25% to 0.4% but pseudoplastic type folw in above 0.5% A maximum viscosity of algin was observed at pH 5.5 and its viscosities were also decreased as the tem-perature increased and heating at 8$0^{\circ}C$ above. Organic acids affected on the viscosity of algin with pH dependently and gel formed in pH below 3.0 Sweetners have no effect to the viscosity of algin. How-ever addition of NaCl and KCL upto 1.0% decreased a little its viscosity and CACl2 MgCl2 and FeCl3 increased the viscosity of algin Glutamic acid decreased the viscosity of algin.

• Tribology and Lubricants
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• v.20 no.2
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• pp.97-101
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• 2004

This paper reports the studies on the wear-corrosion behavior of Al-Mg alloy in various pH environments. In various pH of sea water, corrosion and wear-corrosion loss of Al-Mg alloy were investigated. Also, the polarization test of Al-Mg alloy using potentiostat/galvanostat was carried out. And the rubbed surface of Al-Mg alloy using scanning electron micrographs after wear-corrosion test was examined in various pH values of sea water. The main results are as following : The polarization resistance of Al-Mg alloy in pH 4 solution is higer than that in pH 6.7 solution, and the corrosion current density in pH 4 is controlled than in pH 6.7 solution. The wear-corrosion loss of Al-Mg alloy with lowering pH becomes sensitive. As the oxide product of Al-Mg alloy appears granular structure and exholiation phenomenon, wear-corrosion loss of Al-Mg alloy increases.

• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.145-152
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• 1998

We conducted this study as a fundamental study on the response of various tree species against acid rain. The tree species used for this study were Zelkova serrata, Robinia pseudoacacia, Quercus acutissima, Prunus serrulata, Ginkgo biloba, Pinus koraiensis and Pinus densiflora. The leaves were examined for the pH changes by treatment time and the chlorophyll content into various pH solution in vitro. The results obtained were as follows ; 1. When the leaves were immersed in the solution of various pH(pH 3.0-pH 6.0) levels, the pH were changed to species specific pH ranges as pH 5.0~pH 5.5 of Z. serrata, pH 5.5~pH 6.0 of R. pseudoacacia, pH 4.5~pH 5.0 of Q. acutissima, pH 5.5~pH 6.0 of P. serrulata, pH 3.5~pH 4.5 of G. biloba, pH 3.5~pH 4.5 of P. koraiensis until 48 hours. However, in case of P. densiflora, it was difficult to find specific pH range of the species. Z. serrata, R. pseudoacacia and P. serrulata showed a little pH increasing by pH 2.0 solution treatment, while other species showed no change by the solution. 2. The amount of chlorophyll contents in Z. serrata, R. pseudoacacia and P. serrulata were decreased after immersing in the pH 2.0 solution. Chlorophyll content was almost constant in other pH levels. Other species showed almost constant chlorophyll contents in various pH levels and treatment time.

• The Korean Journal of Physiology
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• v.9 no.1
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• pp.69-76
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• 1975

Cardiac performances were analyzed in intact turtle heart(Amyda japonica), perfusing with turtle Ringer-Locke's solution containing various hydrogen ion concentration, at several levels of arterial and venous pressure. 1. Ventricular work increased when venous pressure, or venous filling pressure increased, and also increased when arterial pressure increased. 2. The higher the arterial pressure, the lower the cardiac to output, for arterial pressure is the resistance to the ventricular blood flow. On the other hand, in specific arterial pressure, cardiac output was proportional to the venous filling pressure. 3. Heart rates did not change significantly during the perfusion with Ringel· solution of various pH. 4. In the heart Perfused with Ringer solution of various pH, ventricular work was the highest at PH 7.6 (at 6 $cmH_2O$ arterial pressure and 8 $cmH_2O$ venous pressure, the ventricular work was 63.09m$\cdot$cm). However, within the range of pH $7.1{\sim}7.6$, there were no significant changes in cardiac output and ventricular work. Below the level of pH 7.0, ventricular work decreased to less than 56% of maximium value (at $6cmH_2O$ arterial pressure and $8cmH_2O$ venous Pressure, ventricular work was 36.0$gm{\cdot}$ at pH 7.0). At pH 7.7 ventricular work decreased to less than 48% of maximum value (ventricular work: 30.0 $gm{\cdot}$). The nature of the cardiac performance at the various arterial and venous pressures was similar to that of normal heart. 5. Turtle heart seemed to be relatively insensitive to acid-base disturbances. The mechanism of negative inotropic effect of hydrogen ion was discussed.

• Journal of the Korean Applied Science and Technology
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• v.28 no.3
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• pp.284-289
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• 2011

All spectroscopic methods used in this work indicate the instability of tungstophosphates in aqueous solutions and considerable dependence on pH with regard to the dominant species present in the solution. UV spectroscopy indicates that some changes occur in the system but they cannot be specified. IR spectroscopy gives more information on the identification of the dominant species as a function the pH of the solution. NMR spectroscopy provides unique data, which can be used for more accurate interpretation of changes in the solution of various pH values. In the case of aqueous solutions of tungstophosphates, the parent anion was present only in a very acidic solution of ca. pH 1. Some differences in interpretation of the molecular species present under various experimental conditions can be ascribed to some extent to the diversity of chemical shifts of NMR. Under physiological conditions attained with the addition of NaOH, tungstophosphates was dominantly present in the form of the lacunary monovacant anion.

• Nuclear Engineering and Technology
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• v.45 no.1
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• pp.107-114
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• 2013

It is required that the pH of the sump solution should be above 7.0 to retain iodine in a liquid phase and be within the material compatibility constraints under LOCA condition of PWR. The pH of the sump solution can be determined by conventional chemical equilibrium constants or by the minimization of Gibbs free energy. The latter method developed as a computer code called SOLGASMIX-PV is more convenient than the former since various chemical components can be easily treated under LOCA conditions. In this study, SOLGASMIX-PV code was modified to accommodate the acidic and basic materials produced by radiolysis reactions and to calculate the pH of the sump solution. When the computed pH was compared with measured by the ORNL experiment to verify the reliability of the modified code, the error between two values was within 0.3 pH. Finally, two cases of calculation were performed for the SKN 3&4 and UCN 1&2. As results, pH of the sump solution for the SKN 3&4 was between 7.02 and 7.45, and for the UCN 1&2 plant between 8.07 and 9.41. Furthermore, it was found that the radiolysis reactions have insignificant effects on pH because the relative concentrations of HCl, $HNO_3$, and Cs are very low.

• Journal of Pharmaceutical Investigation
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• v.19 no.4
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• pp.213-217
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• 1989

To formulate the stable preparation of Gingko extract injection and to evaluate the stability of the preparation, Gingko extract aqueous solutions having various pH values were prepared and the stability of ginskoflavonglycoside (GFG) was investlfated by high performance liquid chromatography. The stability of GFG decreased as pH increased, while the water solubility of Gingko extract decreased as pH decreased. The optimal pH of the Gingko extract aqueous solution was found to be pH 6.5. The shelf life $(T_{90%})$ of the Gingko extract aqueous solution of pH 6.5 at $20^{\circ}C$ was extrapolated to be four years.

• Journal of the Korean institute of surface engineering
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• v.44 no.3
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• pp.117-123
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• 2011

We investigated the spectroscopic and electrochemical properties of the citrate-based CuNi solution at different solution pH and analyzed various surface properties of CuNi codeposition layer. By combining UV-Visible spectroscopic data with potentiodynamic polarization curves, it could be found that the complexation of $Ni^{2+}$-citrate pair was completed at lower solution pH than $Cu^{2+}$-citrate pair and was affected by the coexistent $Cu^{2+}$ ions, while the complexation between $Cu^{2+}$ ions and citrate was not sensitive to the presence of $Ni^{2+}$ ions. Also, the electron transfer from cathode to $Cu^{2+}$-citrate and$Ni^{2+}$-citrate was hindered by strong complexation between $Cu^{2+}/Ni^{2+}$ ions and citrate and so apparent codeposition current densities were reduced as the solution pH increases. CuNi codeposited layers had a higher Cu content when they were prepared at high pH solution due to the suppression of Ni deposition, and when codeposition was executed in an agitated condition due to the acceleration of mass transfer of $Cu^{2+}$ ions in the solution. Actually, solution pH had little effect on the surface morphology and deposits orientation, but greatly influenced the corrosion resistance in 3.5% NaCl solution by modifying the chemical composition of CuNi layers and so pH 3 was expected as the most suitable solution pH in the viewpoint of corrosion coatings.

• Journal of the Korea Institute of Building Construction
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• v.8 no.4
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• pp.79-85
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• 2008

The purpose of this study is to evaluate the mix design of pH reducing cement concrete which can be used for environment-friendly concrete. Cement pastes and concretes are prepared with water-binder ratios and various admixtures such as blast-furnace slag, fly ash and recycled cement, and tested for compressive strength and pH. pH is measured through pore solution expressed from hydrated cement paste by special apparatus. From the test results, regardless of water-binder ratio, The pH of expressed pore solution from hydrated cement paste which is made of ordinary portland cement with blast-furnace slag, fly ash is decreased with increasing of admixtures content, and compressive strength is also slightly improved. The compressive strength of cement paste made of recycled cement which is burnt at $1000^{\circ}C$, for 2 hours is considerably increased compared with that of none-burnt recycled cement due to restoration of hydraulic property, but pH is a little higher. Porous concrete with ordinary portland cement has high pH in the range of 12.22 to 12.59, however, that is reduced to the range of 8.95 to 10.39 by carbonation at the surface of porous concrete. The pH reduction of porous concrete is possible by various admixture addition, however their degrees are very slight. Therefore, to reduce the pH considerably, carbonation method of porous concrete is better in pH reduction methods for plant survival condition of pH of 9.0 or less. In this study, it is apparent that pH for the environment-friendly porous concrete products used in the construction field can be suppressed by this carbonation method and various admixtures addition.