• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.571-574
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• 2000

Hydrolase is a group of the most widely used enzymes in industrial biological processes. Generally, their activities are easily changed with pH. With this characteristics, research for the optimal pH of hydrolases is required to obtain the optimization of process conditions. We selected xylanase, lysozyme, glucoamylase and barnase as model enzymes. To predict optimum pH of hydrolases, the calculation program based on Tanford-Kirkwood(TK) model was used. Results show that charge difference of catalytic residues is an important parameter deciding optimum pH and when charge difference of catalytic residues is maximum, optimum pH of the hydrolase establishes.

• The Korean Journal of Food And Nutrition
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• v.9 no.1
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• pp.52-58
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• 1996

This study was carried out 19 investigate the characteristics of pectinesterase (PE), polygalacturonase (PG), lipoxygenase(LOX) and peroxidase (POD) in hot pepper to know the effect of hot pepper on food quality during food processing and storage. The results were as follows : 1. The optimum pH of PE was pH 7.5 and the activity of PE below pH 5.5 was revealed scarcely, The concentration of NaCl and $CaCl_2$ that showed the highest activity of PE were 0.2M and 0.05M, respectively. 2. The optimum pH of PG was pH 6.0 and the activity of PG in acidity was higher than that in alkalinity. The activity of PG was maximum at 0.3M NaCl and 0.2mM $CaCl_2$. Above the concentration of 0.5M NaCl and 0.5M $CaCl_2$, the activity of PG was lower than that of PG not adding these salts 3. The optimum pH of LOX was pH 7.0 and pH 8.5. 4. The optimum pH of POD was pH 6.0 and the activity of POD was higher in weak acidity and neutrality than in alkalinity. POD activity was slightly decreased by the increase of NaCl and $CaCl_2$ concentration.

• Journal of Environmental Science International
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• v.12 no.8
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• pp.861-870
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• 2003

Using a simple continuous optical technique, coupled with measurements of zeta potential, the effects of polyelectrolyte dosage, kaoline particles and pH on flocculation of humic acid by several cationic polyelectrolytes, have been examined. The charge density of a polyelectolyte is important in determining the optimum dosage and in the removal of humic acid. The optimum dosage is less for the polyelectrolytes of higher charge density and is the same regardless of the presence of kaoline particles of different turbidity. At the dosage, the removal of humic acid is higher for the polyelectrolytes of higher charge density and the zeta potential of humic acid approaches to near zero, With increasing pH of humic acid, the optimum dosage increases and the flocculation index value obtained at the dosage decreases in the following pH 7 ＞ pH 5 ＞ pH 9, regardless of polyelectrolytes.

• Journal of Applied Biological Chemistry
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• v.61 no.1
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• pp.59-67
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• 2018

This study was conducted to isolate the cellulolytic bacteria able to grow on LB- Carboxymethyl cellulose (CMC) agar trypan blue medium from the mixed forest and Larix leptolepis stands. Three bacterial strains with high activity against both CMC and xylan were isolated. Both API kit test and 16S rRNA gene sequence analysis revealed that the three different isolates belong to the gene Bacillus. Therefore, the isolates named as Bacillus sp. EFL1, Bacillus sp. EFL2, and Bacillus sp. EFP3. The optimum growth temperature of Bacillus sp. EFL1, EFL2, and EFP3 were $37^{\circ}C$. The optimum temperature for CMCase and xylanase from Bacillus sp. EFL1 were $50^{\circ}C$. The optimum pH of Bacillus sp. EFL1 xylanase was pH 5.0 but the optimum pH of CMCase from Bacillus sp. EFL1 was pH 6.0. The optimum temperature of CMCase and xylanase from Bacillus sp. EFL2 was $60^{\circ}C$, respectively. The optimum pH of CMCase of Bacillus sp. EFL2 was 5.0, whereas xylanase showed high activity at pH 3.0-9.0. The optimum temperature for CMCase and xylanase of Bacillus sp. EFP3 was $50^{\circ}C$. The optimum pH for CMCase and xylanse was 5.0 and 4.0, respectively. CMCases from Bacillus sp. EFL1, EFL2, and EFP3 were thermally unstable. Although xylanase from Bacillus sp. EFL1 and EFP3 showed to be thermally unstable, xylanase from Bacillus sp. EFL2 showed to be thermally stable. Therefore, Bacillus sp. EFL2 has great potential for animal feed, biofuels, and food industry applications.

• 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.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.5
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• pp.581-593
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• 2010

The objectives of this study were to investigate the effects of raw water pH and basicity of coagulants on turbidity removal with several raw waters having different level of turbidity, alkalinity and pH. Raw waters were sampled from M, S and B water treatment plants(WTP) located at Miryang, Nakdong, Han river, respectively. Six coagulants which have different levels of basicity and aluminum contents were used for this evaluation. High basicity of the coagulant helped to properly control coagulation processes for treating turbid and low alkali raw water. It was difficult for operators to determine optimum coagulant dose for high basicity coagulants, since residual turbidity tended to decrease continuously as coagulant dose increased. Turbidity removal efficiencies with high basicity coagulants(E and F) were higher than the other coagulants at ambient pH for the M WTP. Turbidity removal efficiencies, however, at adjusted pH 7.0 showed similar among six coagulants. Residual turbidity kept low at excess dosages with high basicity coagulants. Optimum coagulant dosages at adjusted pH 7.0 showed higher than those at ambient pH in M WTP. On the contrary in B WTP, optimum coagulant dosage at ambient pH were higher than that at adjusted pH 7.0.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.115-124
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• 1999

This study was conducted to determine the optimum root zone environment condition and proper nutrient management system for lettuce in hydroponics. For the root zone environment condition, several level of pH and electrical conductivity (EC) were treated respectively. Though all the level of pH 4 to pH 8, except pH 3, performed better growth without any visible physiological disorder, the optimum pH of the nutrient solution for lettuce production was pH 5.5 to 6.0. The optimum ionic strength of the solution was EC 1.2 to 1.6 mS $cm^{-1}$ / because higher nutrient level caused tip burn symptom by calcium deficiency. Considering the above results, it is concluded that lettuce can be efficiently mass-produced through the optimum root zone environment.

• YAKHAK HOEJI
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• v.6 no.1
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• pp.5-7
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• 1962

Like the condensation reaction of general aldehyde, that of benzaldehyde with semicarbazide also depends upon the concentration of carbonium ion that is produced by hydrogen ion. The lower pH value is the facility of the formation of carbonium ion in the condensation reaction, while the reactivity of semicarbazide as a reactant is reduced. In this paper, therefore we want to find out the optimum pH value in the condensation reaction of benzaldehyde with semicarbazide. This optimum pH value was determined by using the simple paper-chromatographic method. According to the result of this experiment, the condensation reaction between benzaldehyde and semicarbazide reacts with its highest point at 3.5pH value. It seems clear that at this point the benzaldehyde acquires the most suitable amount of carbonium ion for the condensation reaction with semicarbazide, and the semicarbazide also has the optimum reactivity.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.274-280
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• 2007

The photochemical decolorization of Rhodamine B (RhB) in water has been carried out by photo-Fenton process. The effect of applied $H_2O_2$, $Fe^{2+}$ dose, solution pH and UV dose have been studied. The influence of constituent processes of photo-Fenton such as UV, $H_2O_2$ and Fenton has been investigated. Comparison of RhB removal was made between the photo-Fenton and $UV/H_2O_2$ process. The results obtained showed that the optimum dosage of $Fe^{2+}$ and $H_2O_2$ were 0.0031 mmol and 0.625 mol, respectively. pH 3 is found to be the optimum pH of for photo-Fenton process. pH and UV dose strongly influenced the decolorization of RhB in photo-Fenton process. The photo-Fenton and $UV/H_2O_2$ processes showed similar decolorization and seem to be appropriate for the decolorization of dye wastewater.

• Analytical Science and Technology
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• v.16 no.6
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• pp.504-508
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• 2003

A carbon paste electrode was constructed with peroxidase extracted from Horseradish and the variation of the response of the sensor with pH was investigated. Current profiles showed two highest sensitivities at two pH values respectively. In addition, two bands were observed in the electrophoretic expansion. A coincidence of the two experimental results added support to the possibility that the biosensor has two different isozymes. Assuming that current profiles are the sum of two gaussians, we deconvoluted them and determined the optimum pH of peroxidase isozymes.