• Restorative Dentistry and Endodontics
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• 제15권1호
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• pp.88-96
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• 1990

The purpose of this study was to investigate the fluoride release and solubility of glass ionomer cement associated with three pH media. For this study, GC Fuji II discs (20.0mm in diameter ${\times}$ 1.5mm thick) were immersed in pH 4.0 lactic acid, pH 7.0 distilled water and pH 10.0 KOH solutions for 1, 7, 14 and 28 days. The amount of fluoride release from the cement into three pH media were measured by fluoride specific ion electrode and the solubility was measured by weight loss of discs. The results were as follows: 1. The lower was the pH of media, the more was the amount of release of fluoride. 2. The amount of fluoride release was increased with time lapse. 3. After I day, the solubility was the highest, and after 7 days that was the least. 4. The lower was the pH of media, the more was the solubility, but there was no statistical difference in solubility according to the pH change.

• 한국물환경학회지
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• 제18권4호
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• pp.401-409
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• 2002

In this study, to evaluate the applicability of ORP and pH as process control parameters for an intermittent aeration process, a 200L/d bench-scale plant was installed and operated for 90 days. It was fed with synthetic wastewater which contained $COD_{Cr}$ : 400mg/L, TN : 40mg/L and TP : 7mg/L. ORP & pH were measured on-line and compared with the variation of nutrient concentrations. As the results, both of the ORP and pH were able to monitor successfully nitrification and denitrification. Bending-points on the ORP curve and peak points on the pH curve corresponded to the termination of nitrification and denitrification. For P uptake and release, pH was the best indicator for performance evaluation. The aerobic pH apex was appeared when P uptake was accomplished and there was a relationship between the P release and pH variation. But the pH curve needed filtering because there were many noises on it. In this study, the shape of the ORP & pH curves were varied as the operating conditions such as aeration rates and organic loads were changed. It allowed the operating states of biological systems to be effectively evaluated. If it is properly managed to show the bending points and peak points clearly, the on-line monitoring of ORP & pH will be a reliable and effective technique for process control of intermittent aeration processes.

• 한국환경보건학회지
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• 제30권2호
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• pp.104-107
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• 2004

This study was conducted to evaluate the effects of pH, using gametes, embryos and early development system of three sea urchins species, Hemicentrotus pulcherrimus, Anthocidaris crassispina and Scaphechinus brevis. As the result of performing effects of pH on early embryo development, the conditions of appropriate pH on formation of normal pluteus were pH 7.0-8.0 for H. pulcherrimus, A. crassispina and S. brevis. Otherwise, the conditions of pH 5.0, pH 6.0, pH 9.0 and pH 10.0 damaged the development of early embryos of each testing animal moderately or strongly.

• 한국가축번식학회지
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• 제15권3호
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• pp.195-199
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• 1991

This study was carried out ot investigate effect of pH stimulation on acrosome reaction of bovine spermatozoa. The results obtained were as follows : 1. When sperm was sequentially washed with SHP solution of pH 7.4, 7.7 and 7.4 and incubated in mTALP solution of pH 7.4 for 120min, 15, 30, 60 and 120min incubations showed significantly(p<0.05) higher sperm acrosome reaction rate than 0 min. 2. When sperm was sequentially washed with SHP solution of pH 7.4, 8.0 and 7.4 and incubated in mTALP solution of pH 7.4 for 15 minutes, sperm acrosome reaction rate was significantly(p<0.01) increased until 9 min. Incubation, but not increased thereafter. 3. When sperm were separately washed with SHP solutions of pH 7.0, 7.4 and 8.0 and incubated in mTALP solution of pH 7.4 for 9min, sperm acrosome reaction rate was 74.8, 71.8 and 93.4%. pH 8.0 showed signifciantly(p<0.01) higher sperm acrosome reaction rate than pH 7.0 and 7.4. The results suggest that stimulation of sperm with high pH induces sperm crosome reaction.

• 한국식품조리과학회지
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• 제9권1호
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• pp.43-51
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• 1993

Buckwheat protein isolate was tested for the effects of pH, addition of sodium chloride and heat treatment on solubility, emulsion capacities, emulsion stability, surface hydrophobicity, foam capacities and foam stability. The solubility of buckwheat protein isolate was affected by pH and showed the lowest value at pH 4.5, the isoelectric point of buckwheat protein isolate. The solubility significantly as the pH value reached closer to either ends of the pH, i.e., pH 1.0 and 11.0. The effects of NaCl concentration on solubility were as follows; at pH 2.0, the solubility significantly decreased when NaCl was added; at pH 4.5, it increased above 0.6 M; at pH 7.0 it increased; and at pH 9.0 it decreased. The solubility increased above $80^{\circ}C$, at all pH ranges. The emulsion capacity was the lowest at pH 4.5. It significantly increased as the pH approached higher acidic or alkalic regions. At pH 2.0, when NaCl was added, the emulsion capacity decreased, but it increased at pH 4.5 and showed the maximum value at pH 7.0 and 9.0 with 0.6 M and 0.8 M NaCl concentrations. Upon heating, the emulsion capacity decreased at acidic pH's but was maximised at pH 7.0 and 9.0 on $60^{\circ}C$ heat treatment. The emulsion stability was the lowest at pH 4.5 but increased with heat treatment. At acidic pH, the emulsion stability increased with the increase in NaCl concentration but decreased at pH 7.0 and 9.0. Generally, at other pH ranges, the emulsion stability was decreased with increased heating temperature. The surface hydrophobicity showed the highest value at pH 2.0 and the lowest value at pH 11.0. As NaCl concentrationed, the surface hydrophobicity decreased at acidic pH. The NaCl concentration had no significant effects on surface hydrophobicity at pH 7.0, 9.0 except for the highest value observed at 0.8 M and 0.4 M. At all pH ranges, the surface hydrophobicity was increased, when the temperature increased. The foam capacity decreased, with increased in pH value. At acidic pH, the foam capacity was decreased with the increased in NaCl concentration. The highest value was observed upon adding 0.2 M or 0.4 M NaCl at pH 7.0 and 9.0. Heat treatments of $60^{\circ}C$ and $40^{\circ}C$ showed the highest foam capacity values at pH 2.0 and 4.5, respectively. At pH 7.0 and 9.0, the foam capacity decreased with the increased in temperature. The foam stability was not significantly related to different pH values. The addition of 0.4 M NaCl at pH 2.0, 7.0 and 9.0 showed the highest stability and the addition of 1.0 M at pH 4.5 showed the lowest. The higher the heating temperature, the lower the foam stability at pH 2.0 and 9.0. However, the foam stability increased at pH 4.5 and 7.0 before reaching $80^{\circ}C$.

• Macromolecular Research
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• 제13권6호
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• pp.467-476
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• 2005

The main objective of this study was to develop and characterize pH-sensitive biodegradable polymeric materials. For pH-sensitivity, we employed three kinds of moieties: 2-amino-3-(lH-imidazol-4-yl)-propionic acid (H), N-[4-( 4,6-dimethyl-pyrimidin-2ylsulfamoyl)-phenyl]succinamic acid (SM), and 2- {3-[ 4-( 4,6-dimethyl-pyrim­idin- 2-ylsulfamoyl)-phenylcarbamoyl]-propionylamino} -3-(3 H - imidazol-4-yl)-propionic acid (SH). The pH -sensitive diblock copolymers were synthesized by ring opening polymerization and coupling reaction from poly(ethylene glycol) (MPEG), $\varepsilon$-caprolactone (CL), D,L-lactide (LA) and pH-sensitive moieties. The pH-sensitive SH molecule was synthesized in a two-step reaction. The first step involved the synthesis of SHM, a methyl ester derivative of SH, by coupling reaction of SM and L-histidine methyl ester dihydrochloride, whereas the second step involved the hydrolysis of the same. The synthesized SM, SHM and SH molecules were characterized by FTIR, $^{1}H$-NMR and $^{13}C$-NMR spectroscopy, whereas diblock copolymers and pH-sensitive diblock copolymer were characterized by $^{1}H$-NMR and GPC analysis. The critical micelle concentrations were determined at various pH conditions by fluorescence technique using pyrene as a probe. The micellization and demicellization studies of pH-sensitive diblock copolymers were also done at different pH conditions. The pH-sensitivity was further established by acid-based titration and DLS analysis.

• 유기물자원화
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• 제14권1호
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• pp.131-138
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• 2006

본 연구는 혐기성 발효를 이용한 수소생산과정에서 pH를 일정하게 유지한 상태에서 안정적인 수소를 생산하기 위한 최적 pH를 찾고자 하였다. 실험결과 pH 6이었을 때 최적의 조건이었으며 이때 수소생산량은 1175.87 mL/L 이고, 이론적 수소 전환율은 22.51 %였다. pH 5는 901.77 mL/L의 수소가 발생되었으며, 수소 전환율은 17.48 %, pH 7은 454.26 mL/L의 수소생산량과 8.74 %의 수소 전환율을 나타내었다. 그리고 pH 7과 8에서는 각각 452.08 mL/L와 82.25 mL/L의 저조한 수소 생산량을 나타내었다. 자당의 혐기성 발효를 통한 유기산 생성에 있어서 pH가 7과 8에서는 propionate가 주로 관찰되었으나 pH가 5와 6인 영역 에서는 butyrate의 생성이 두드러지는 결과가 나타났다.

• 한국식품과학회지
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• 제30권3호
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• pp.557-561
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• 1998

본 연구에서는 산성(pH 2.0, 3.0), 중성(pH 7.0) 및 알칼리성(pH 10.0, 12.0)영역에서 각각 추출된 SPI들의 기능성을 상호비교하였다. pH 3.0에서 추출된 SPI의 단백질함량은 93.31%로 최고값을, pH 7.0에서 추출된 SPI의 단백질함량은 73.93%로 최소값을 나타내었다. pH 3.0에서 추출된 SPI의 추출수율은 0.36%로 최소값을, pH 12.0에서 추출된 SPI의 추출수율은 47.54%로 최고값을 나타내었다. SPI의 기능성(용해도, 수분흡수력, 유지흡수력, 기포형성력, 기포안정성, 유화형성력 및 겔형성력)은 대두단백질 추출시 추출용액의 pH에 의해 크게 좌우되었다. pH 2.0과 3.0에서 추출된 SPI의 용해도는 산성영역에서 크게 나타났고 pH 3.0과 7.0에서 추출된 SPI는 중성 영역에서 높은 용해도를 보였으나 pH 2.0, 3.0, 7.0, 10.0 및 12.0에서 추출된 SPI는 모두 알칼리성 영역(pH 9.0-10.0)에서 높은 용해도를 나타내었다. pH 2.0과 pH 12.0에서 추출된 SPI의 수분흡수력, 유지흡수력, 기포형성력 및 기포안정성은 다른 pH에서 추출된 SPI보다 크게 나타났으나 유화력의 경우 추출용액의 pH가 증가할수록 유화력이 증가하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.325-326
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• 2009

본 연구에서는 물-시멘트 비에 따른 시멘트계 재료인 시멘트 페이스트, 모르터 및 콘크리트의 pH 저하 저항성을 평가하였다. 우선 시멘트 페이스트에 대해 물-시멘트 비 30%, 40%, 50% 인 보통 포틀랜드 시멘트 페이스트의 산 증가에 따른 pH를 측정하였다. 또한, 페이스트의 pH 저하 저항성에 대한 골재의 영향에 대해 알아보기 위해서 콘크리트, 모르터, 페이스트의 pH 저하 저항성 측정 실험도 수행하였다. 실험결과, 산이 증가할수록 pH는 감소하였으며 특히 pH 10 정도에서 급격한 pH 저하가 발생되었다. 산 증가에 따른 pH 감소정도는 산중화능력으로 나타내었으며 시멘트 수화물에 의해 특정 pH에서 산중화능력이 물-시멘트비에 따라 높게 나타났다.

• 한국연초학회지
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• 제19권1호
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• pp.46-50
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• 1997

The pH of coconut based activated carbon was changed by treating with NaOH and HNO3 and we have calculated the adsorption amounts of ammonia, hydrogen sulfide and methylmercaptan on the activated carbons using the break-through time which was obtained from break-through curve experiments. As a result of this study, the adsorption amounts of ammonia Has on the activated carbons were 2,6 mg/g, 17.2 mg/g and 31.6 mg/g with the pH 11, pH 7 and pH 3, respectively. These results indicated that the adsorption ability of ammonia on activated carbon was increased with decreasing the pH of activated carbon. Otherwise, in the cases of the adsorption experiment of hydrogen sulfide and methylmercaptan on the activated carbons with different pH. the activated carbon with pH 11 showed higher adsorption capacity than the activated carbons with pH 7 and pH 3. The adsorption amounts of hydrogen sulfide and methylmercaptan were 39.9 mg/g and 178 mg/g with pH 11, respectively. Finally, we analyzed the amount of ammonia delivered from 88 Lights cigarette made of triple filter which contained the activated carbon. The amount of ammonia delivered to smoke from the filter cigarette containing the activated carbon with pH 3 was 45.1${\mu}g$/cig. This value was lower 23.8 % than that from the activated carbon with the pH 11.