• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.399-403
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• 1999

Effects of heating, pH, organic acids and some salts on color changes of ground garlic, expressed by Hunter color values, were investigated during storage. The organic acids, such as acetic, citric and lactic acids rather enhanced greening, while NaCl affected little. As the pH decreased to 4.0, greening was significantly reduced. Among the several phosphates tested, $Na_{2}HPO_{4}\;and\;Na_{3}PO_{4}$ showed some positive effects and other chemicals, such as BHA, BHT, propyl gallate and glutathione showed little or negative effects on both greening and browning of ground garlic. Heating at $80^{\circ}C$ for up to 10 mins at pH range of $3.0{\sim}5.0$ caused a severe greening mostly, while heating at $90\;and\;100^{\circ}C$ for 30 mins or longer resulted in a decrease in greening and an increase in yellow color of ground garlic.

• Journal of the Korean Chemical Society
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• v.40 no.9
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• pp.599-606
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• 1996

The effects of chemical species in groundwater on the solubility of the uranyl hydrolysis precipitates formed at pH 6.4 and 9.7 were investigated. Based on the chemical composition of the groundwater, the synthetic groundwater was prepared. The colloid-free (separated) groundwater was also prepared by removal of both organic and inorganic colloids from the sampled groundwater. Solubilities of precipitates formed in the hydrolysis of uranyl ion in groundwater, separated groundwater, synthetic groundwater and 0.1 M NaCl solution were measured over neutral to alkaline pH range, and especially, the effect of the anions and cations found in groundwater on the solubility was investigated. Solubility in groundwater was approximately two orders of magnitude greater than that in 0.1 M NaCl solution. Soubililties of uranyl hydrolysis precipitates formed at pH 9.7 and 6.4 were compared in groundwater and synthetic groundwater. Solubilities of the precipitates formed at different pH were found to be in the same order of magnitude in groundwater and synthetic groundwater, however the uranyl hydolysis precipitates formed at higher pH values showed a tendency of higher solubility.

• KSBB Journal
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• v.20 no.6
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• pp.464-469
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• 2005

For the biological production of hydrogen, a new fermentative hydrogen-producing bacterium, Enterobacter sp. SNU-1453, was isolated from a domestic landfill. During the culture of this bacterium, pH significantly decreased with the accumulation of various organic acids, and consequently this inhibited the production of hydrogen. It was found that the metabolic flux in this bacterium depended on the pH and affected the hydrogen production. A butanediol pathway was dominant during the fermentation when pH was not controlled. By controlling the pH at 7 this pathway can be shifted to a mixed acid pathway, which is favorable to the production of hydrogen.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.17-22
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• 2013

In this study, a pH control method by carbon dioxide ($CO_2$) was applied to coagulation process in water treatment plant (WTP) to investigate the coagulation efficiency and residual dissolved aluminum when high pH raw water is flowing into the plant during algal blooming. Existing coagulant dose (1 mg/L in raw water) resulted in the pH reduction of 0.0384 by LAS, 0.0254 by PAC, 0.0201 by A-PAC, and 0.0135 by PACS2, respectively. And then the concentration of dissolved aluminum was 0.02 mg/L at pH 7.44, 0.07 mg/L at pH 7.96, 0.12 mg/L at pH 8.16, 0.39 mg/L at pH 8.38 showing the concentration increase with pH in the coagulation process. It was noteworthy that rapid increase was observed at pH above 8.0 next the rapid mixing. Therefore it is necessarily required to control pH below 7.8 in the coagulation process in order to meet drinking water quality standard of aluminum for high pH raw water into WTP, $CO_2$ injection could control pH successfully at about 7.3 even for the raw water of high pH above 8.0. In addition it was found that the pH control by $CO_2$ injection was significantly effective for coagulation in terms of turbidity removal, coagulant dosage, and residual dissolved aluminum concentration.

• Journal of Animal Science and Technology
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• v.47 no.4
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• pp.615-624
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• 2005

The cPCR technique was used to monitor rumen fermentation and attachment of Fibrobacter succinogenes to cellulose at different pH in the in vitro culture medium. The target fragments of 16S rDNA(445 bp) were amplified from genomic DNA of F. succinogenes with specific primers and internal controls(205 bp) were constructed. Cell counts were estimated from the amounts of genomic DNA, which was calculated from cPCR results. F. succinogenes in pH 6.8 and 6.2 showed apparently higher attachment than in pH 5.8 during all incubation time. There were some difference between pH 6.8 and 6.2 in the degree of attachment, but the different was not significant (P>0.05). Cellulose degradation increased in process of incubation time and the increasing rate was higher when initial pH was higher. The pH in culture medium decreased regardless of initial pH in course of incubation time. After 24 h of incubation, medium pH was dropped by 0.24, 0.58 and 0.16 units from original medium pH 6.8, 6.2 and 5.8, respectively. More gas was produced at higher initial pH in the same manner as in cellulose degradation. In summery, Initial pH of rumen culture in vitro significantly influenced cellulose digestion, gas production, pH change and bacterial attachment. Especially, low pH(5.8) resulted in much lower bacterial attachment and fiber digestion compared to higher medium pH.

• Journal of Adhesion and Interface
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• v.11 no.3
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• pp.89-99
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• 2010

In this paper, for polymerization of poly(vinyl acetate-co-ethylene) (VAE) by redox system using poly(vinyl alcohol) (PVOH) as emulsifier on the properties of the final emulsion, and pH changes affect the physical properties of the final emulsion was investigated. The results of the molecular weight of PVOH had a dramatic impact on the emulsion properties. The used a low molecular weight of PVOH products was obtained low viscosity and using the high molecular weight of PVOH were obtained high viscosity product. However, changing the pH of the final polymerized product properties for the PVOH obtained different results. Generally, a poly(vinyl acetate) emulsion by a high degree of polymerization and high molecular weight of PVOH was obtained high viscosity of the final emulsion. But, in VAE was lower emulsion viscosity in high pH. This is the molecular weight of the emulsion during the synthesis of PVOH is considered to be affected by degradation. The final viscosity was decreased by grafting ratio and molecular weight were decreased with increasing of pH.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.5
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• pp.228-235
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• 2016

Nitrite accumulation is essential for constructing an anammox process. As the pH in the reactor exerts a complicated and strong influence on the reaction rate, we investigated its effects upon treatment of an ammonic wastewater (2,000 mgN/L) through modeling and experiment. The modeling results indicated that the reaction stability is strongly affected by pH, which results in a severe reduction of the 'stable region' of operation under alkaline environments. On a coordinate of the total ammonia nitrogen (TAN) concentration vs. pH, the maximal stable reaction rates and the maximal nitrite accumulation potentials could be found on the 'stability ridge' that separates the stable region from the unstable region. We achieved a stable and high ammonia oxidation rate (${\sim}6kgN/m^3-d$) with a nitrite accumulation ratio of ~99% when operated near the 'stability ridge'. The optimum pH that can be observed in experiments varies with the TAN concentrations utilized, although the intrinsic optimum pH is fixed. The direction of change is that the optimum operational pH falls as the TAN concentration increases, which is in excellent accordance with the observations in the literature. The optimum operational pH for 95% nitritation was predicted to be ~8.0, whereas it was ~7.2 for 55% partial nitritation to produce an anammox feed in our experimental conditions.

• Applied Biological Chemistry
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• v.29 no.2
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• pp.212-218
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• 1986

Proteins in Korean rapeseeds, as in many other plantseeds, are usually bound to phytate molecules. These phytate-bound proteins are of little value as foodstuffs because of their poor solubility in digestive systems. Therefore it is necessary to remove phytates from proteins in order to convert these proteins io a useful foodstuff. In the work, an efficient procedure for removal of phytates from defatted Korean rapeseed was found. The influence of pH on the solubility of protein and phytate of rapeseed flour showed that the former was the lowest at pH 5.0 and began to increase as pH further raised. Meanwhile, the latter was the highest at pH 6.0, however, it was decreased abruptly at alkaline pH, especially to content of 1.3% at pH 11.5. The solubility cf protein was relatively high in NaCl aqueous solution at $pH\;6.0{\sim}8.0$, and did not male any noticeable difference depending on NaCl concentration. On the other hand, the solubility of phytate was high at pH of below 6.0 showing an abrupt decrease at pH of above 6.0. The solubility of protein in $CaCl_2$ aqueous solution was highest at $pH\;6.0{\sim}8.0$, however, there was no significant change at the whole range of tested pH of the solution. A maximum solubility of phytate was shown at $pH\;3.0{\sim}4.0$. And it was decreased abruptly at a higher pH of the above range and also decreased at a lower pH with higher $CaCl_2$ concentration. The solubility of phytate in $Na_2SO_3$ aqueous solution was highest at $pH\;5.0{\sim}8.0$. As the concentration goes up the maximum value of solubility was found to move to higher pHs. Depending on the concentration of $Na_2SO_3$, the decreasing pattern was changed in an alkaline solution. The solubility of phytate in the solution containing low concentration of $Ca^{2+}$ ion was low in all treatments at pH of above 7.0 and showed the maximum value at low pH as $Ca^{2+}$ ion concentration increases. The solubility of protein at pH 11.5 showed the highest value in $1mM\;Ca^{2+}$ ion solution.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.590-598
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• 2007

Syrup form medicines which children commonly take contains sugar as sweeteners. Sugar, low endogenous pH, high acidity, mucosity and low concentrations of ions including those of calcium, fluoride, and phosphate in their composition, they can be cause of caries and erosion. Not only the properties found in such medicines, but also other factors such as high frequency of ingestion, bedtime consumption, and the collateral effect of a reduction in salivary flow, poor oral hygiene of sick children may also contribute to the risk. The other side, parents rarely recognize these risk, and medical experts also easily overlook. The purpose of this study was to investigate the pH level of some syrup form medicines which are frequently administered by infants and young children, and their effects on the changes of plaque pH when rinsing with them. And we compared the salivary pH change induced by rinsing with Cough-syrup only and rinsing with Cough-syrup followed by water. The results were as follows : 1. The average pH of syrup form medicines which were prescribed in Pusan National University Hospital and several OTC syrup form medicines was pH $4.7{\pm}0.94$, within the range of pH 3.0 to 6.8. 2. The plaque pH decreased rapidly below pH 5.5 after rinsing with the syrup form medicines which were selected for the test and there was no statistically significant difference in the of plaque pH change between syrup form medicines except COLDI(p>0.05). 3. There was statistically significant difference in salivary pH change between rinsing with Coughsyrup only and rinsing with water after Cough-syrup(p<0.05).

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.45-51
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• 2005

$K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$ in the $K_2O-Li_2O-Al_2O_3$ ternary system was synthesized using aluminum nitrate solution as a starting material. For the synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$, raw materials with chemical composition of $0.84K_2O{\cdot}0.082Li_2O{\cdot}5.2Al_2O_3$ were mixed in solution state. The effects of dispersant and solution-pH were investigated in minimizing the particle size and on the synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$. Ethanol was used for a dispersant, and $NH_4OH$ solution and nitric acid were added for pH adjustment. The solution pH was increased from 1.0 to 7.5 by 0.5 increments. Each sample was calcined at $1200^{\circ}C$ for 2 h and characterized with X-ray diffraction and particle size analyzer. The pH of solution significantly effected both particle size and phase formation, while the addition of ethanol only effected particle size. The synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$ was favored by addition of nitric acid (for pH control).