• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.33-37
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• 1998

The effects of initial pH on the synthesis of new microporus zeolitic materials, ETS-4 and ETS-10 were investigated with the initial pH from 10.4 to 11.5. The results showed that initial pH significantly affect the type of ETS-series materials to be crystallized ; that is, pure ETS-10 at 10.4 of pH, mixture of ETS-10 and ETS-4 at intermediate pH, and pure ETS-4 at pH. Micrographs show that the morphology of final solid product changes from the shape contacting the bottom sides of two truncated pyramids to the plane-like shape as initial pH increases.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.557-561
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• 1998

This study was conducted to investigate the functionality of soybean protein isolates extracted in acidic range (pH 2.0 and 3.0), neutral range (pH 7.0) and alkaline range (pH 10.0 and 12.0). The protein content of soybean protein isolates extracted at pH 3.0 was maximum (93.31%), but that of pH 7.0 was minimum (73.93%). The extraction yield of soybean protein isolates extracted at pH 3.0 was minimum (0.36%), but that of pH 12.0 was maximum (47.54%). The functionality (solubility, water absorption, oil absorption, foam capacity, foam stability, emulsion capacity and gelation) of soybean protein isolates was significantly influenced by pH of extraction medium. The soybean protein isolates extracted at pH 2.0 and 3.0 were more soluble at acidic ranges and those of pH 3.0 and 7.0 were more soluble at neutral ranges, but those of pH 2.0, 3.0, 7.0, 10.0 and 12.0 were more soluble at alkaline ranges than other ranges. The soybean protein isolates extracted at pH 2.0 and pH 12.0 gave greater water absorption, oil absorption and foam capacity than those extracted at pH 3.0, pH 7.0 and pH 10.0. And the emulsion capacity of soybean protein isolates was increased by the increase of extraction pH.

• Food Science of Animal Resources
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• v.20 no.2
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• pp.101-106
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• 2000

Effects of Ph on the activity of lipase isolated from milk fat globules were investigated, using coconut oil and homogenized milk as substrate. With buttermilk as an enzyme source for coconut oil and homogenized milk substrates bell-shaped curve was observed at $37^{\circ}C$, having the highest activity at pH 9.5. However, lipase activity at $0^{\circ}C$ continuously increased up to pH 10.0. With the purified lipase for homogenized milk substrate, the bell -shaped curve and the highest activity were observed at $37^{\circ}C$ and pH 9.0, respectively. Lipase activity at $0^{\circ}C$ increased up to pH 10.0. The addition of bovine serum albumin to the coconut oil shifted the optimum pH to pH 9.5 and the activity remarkably declined at pH 10.0. The effect of pH on the stability of purified lipase was depending on the temperature. Wehn the lipase kept at $37^{\circ}C$ for 20 minutes, it's activity remarkably declined as pH increased: the activity at pH 10.0 was declined by 13% of that pH 8.5. However, when the lipase kept at $4^{\circ}C$ for 60minutes, the activity was stable within the range of pH 7.5 to 10.0.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.502-509
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• 1997

Aromatic pollutants(benzene, toluene, ethylbenzene and xylenes) were photodegraded by using a UV oxidation and the rates of degradation were investigated under various reaction conditions. Each of the solution containing 50 ppm benzene, 150 ppm ethylbenzene and 250 ppm xylenes was found UV-photodegraded over 90% in 1 hour of reaction time, wheras the only was 43 % degradation was obtained with 350 ppm toluene solution. A single component solution was more degradable than a mixed component solution and benzene was almost photodegraded at a pH 4.0, 6.4 and 10.0 after reaction time is 1 hr, ehtylbenzene was photodegraded about 92%(pH 4.0), 90%(pH 6.4) and 91%(pH 10.0), xylenes was photodegraded about 95%(pH 4.0), 90%(pH 6.4) and 92%(pH 10.0), but toluene was photodegraded about 80%(pH 4.0), 43%(pH 6.4) and 70%(pH 10.0), respectively. Kinetics studies show that the rate of decay in TOC(total organic carbon) were pseudo first-order rate except ethylbenzene, and then we could evaluate mineralization rate constants(k) of aromatics.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.417-420
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• 2011

In this experiment, we examined the survival, fertilization, hatching times, and hatching rates of Far Eastern catfish Silurus asotus at pH ranging from 2 to 13 under laboratory conditions. Eggs could be fertilized at pH 3-12. In a hatching experiment, mortality was first observed at pH 13, when all fertilized eggs died within 8 min, followed by pH 2 (30 min), pH 12 (60 min), pH 3 (4 h), and pH 11 (5 h). Hatching only occurred at pH 4-10, with the highest hatching rate at pH 7 (52%) and the lowest at pH 10 (24%). Hatching rates in acid solutions were higher than in alkaline solutions, although the difference was not significant. Hatching was first observed at pH 10, beginning 27 h after fertilization and ending at the 31 h. A clear difference was observed between hatching times, ranging from 31 to 64 h and increasing in order with descending pH.

• Microbiology and Biotechnology Letters
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• v.20 no.4
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• pp.371-376
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• 1992

The growth and cultural characteristics of Bacillus sp. SH-8 and SH-8M were investigated at various pH conditions. Bacillus sp. SH-8 showed normal growth pattern above pH 9.0. However, with the pH adjusted below 7.7, 0.$D_{550}$ decreased rapidly with concomitant reduction in viable cell numbers. In contrast, Bacillus sp. SH-8M demonstrated growth capability at pH 7.7, but with slightly reduced growth rate at pH 6.9. Similar results were obtained when those two strains were cultivated on the solid medium. Both of them showed short rod shapes at pH 10.2. However, at pH 7.7 only Bacillus sp. SH-8 was observed to have elongated rod shape. Extracellular pH of both the strains, when cultured at initial pH of 10.2, reached to 9.0 after the incubation of 28 hours. At the initial pH of 9.0 and 9.6, the extracellular pH was reduced at the beginning of cultivation, but elevated after 12 hours. When cultured at initial pH of 6.9 and 7.7, extracelluar pH of Bacillus sp. SH-8M increased to 8.0 and 8.7, respectively, while that of Bacillus sp. SH8 remained constant pH 7.0. The highest sporulation rate of Bacillus sp. SH-8 and SH-8M was obtained at the initial pH of 10.2 and after the incubation of 3 days with the sporulation rate of 95% and 85%, respectively.

• Journal of the Korean Chemical Society
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• v.60 no.3
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• pp.187-193
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• 2016

In this study, preparation of positively and negatively charged carbon nanotube (CNT)-collagen (CG) hydrogels with pH sensitive characteristic was reported. The positive and negative characteristics of the prepared hydrogels were created by introduction of positively functionalized CNT-NH₂ and negatively functionalized CNT-COOH, respectively, into the collagen hydrogel. The surface charge of CNTs (CNT-NH₂ and CNT-COOH), CG and CNTs/CG hydrogels was measured by Zetasizer. The swelling ratios of CNT-NH₂/CG and CNT-COOH/CG hydrogels in aqueous solution were checked by measuring of weight changes of the hydrogels in the range of pH 2~10. In detail, the positively charged CNT-NH₂/CG hydrogel swelled up to 5% at pH 4 in comparison to the weight at pH 7, while the negatively charged CNT-COOH/CG hydrogel swelled up to 10% at pH 10. The prepared CNT-NH₂/CG and CNT-COOH/CG hydrogels will be very useful as pH sensitive oral drug-delivering systems for gastrointestine (pH ~2) and small intestine (pH ~9), respectively.

• Journal of Environmental Science International
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• v.5 no.2
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• pp.243-252
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• 1996

In order to investigate the effects of pH and organic matter content on cadmium adsorption and exchangeable cations desorption in soils, the adsorption isotherms of cadmium and the desorption isotherms of calcium and magnesium on four New jersey soils at four pH values were plotted, and the cadmium partition coefficients (Kd) were also calculated. The slopes of cadmium adsorption isotherms dramatically increased with increasing solution pH. Judging from Langmuir adsorption equations, the maximum adsorption quantities(b) of cadmium at high pH values were much greater than those at low pH values for the same soil. The partition coefficients increased greatly with increasing solution pH. The slopes of regression equations between partition coefficients and pH values were steep in the order of the organic matter content of the soils. The correlation coefficients (r2) between partition coefficient and organic matter content for soils. The correlation coefficients (r2) between partition coefficient and organic matter content for $1\times10^{-4}$M increased from 0.3027 at pH 4.0 to 0.9964 at pH 8.5 and from 0.2093 at pH4.0 at 0.9657 at pH 8.5 for$2\times10^{-4}$M ${Cd(NO_3)}_2$. The desorption quantities of calcium and magnesium decreased with increasing solution pH and increased with- increasing cadmium adsorption.

• Applied Biological Chemistry
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• v.35 no.5
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• pp.404-409
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• 1992

Hydroxypropylated starches and acetylated starches were prepared by reaction of potato starch with propylene oxide and acetic anhydride, respectively and then degree of retrogradation and swelling power were investigated in different pHs and temperature. The extent of retrogradation determined by glucoamylase method during freeze-thaw treatment and storage in low temperature $(0{\sim}5^{\circ}C)$ showed that modified potato starches were slowly retrograded as the increase of degree of substitution. The order of the retrogradation tendencies in different pHs were pH 4>pH 6>pH 8>pH 10. Retrogradation of hydroxypropylated potato starches were less than that of acetylated potato starches. Swelling power of starches were influenced more by the temperature than by the pH. The order of the swelling power tendencies in different pHs were pH 10>pH 2>pH 8>pH 4>pH 6.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.337-341
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• 1998

The morphological and cultural characteristics of alkalophilic Coryneform bacteria TU-19 were investigated at various pHs. This bacterium showed normal growth pattern at $pH\;9.0{\sim}10.0$, but the cell growth was completely inhibited at extreme pH (12.0 or more). Interestingly, at pH 8.0 the morphology of the bacterial cells seems to form convoluted filaments during the exponential growth phase while at pH 10.0, the optimal pH for the growth of this organism, the bacteria grew with variable paired or single forms, and straight rods during growth stages. Growing in alkaline media $(pH\;9.0{\sim}11.0)$, it adjusted the pH of the culture media to around pH 8.5 by itself.