• Corrosion Science and Technology
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• 제2권1호
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• pp.12-17
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• 2003

The effects of Cr content and film formation potential on electronic behaviors of the passive film on Fe-Cr alloys were investigated in borate buffer solution. Influence of pH on passive films of both Fe-Cr and Fe-Cr-Mo alloys was also investigated. Mott-Schottky and cyclic voltammetry techniques were used to elucidate electronic behaviors of passive films and their electrochemical characteristics. AES analysis of passive films was carried out. Results showed that doping density decreased as Cr content and film formation potentials increased. The addition of Mo to Fe-Cr alloy had little influence on donor densities in pH 9.2 solution but some effects on the decrease in donor densities in pH 1.6 acidic solution.

• Food Science and Biotechnology
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• 제16권6호
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• pp.999-1005
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• 2007

An oil-in-water (O/W) emulsion [20 wt% com oil, 0.5-6.0 wt% fish gelatin (FG), pH 3.0] was produced by high pressure homogenization, and the influence of pH, protein concentration, and homogenization condition on the formation of FG-stabilized emulsions was assessed by measuring particle size distribution, electrical charge, creaming stability, microstructure, and free FG concentration in the emulsions. Optical microscopy indicated that there were some large droplets ($d>10\;{\mu}m$) in all FG-emulsions, nevertheless, the amount of large droplets tended to decrease with increasing FG concentration. More than 90% of FG was present free in the continuous phase of the emulsions. To facilitate droplet disruption and prevent droplet coalescence within the homogenizer, homogenization time was adjusted in O/W emulsions stabilized by 2.0 or 4.0 wt% FG. However, the increase in the number of pass rather promoted droplet coalescence. This study has shown that the FG may have some limited use as a protein emulsifier in O/W emulsions.

• 아시안잔디학회지
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• 제9권3호
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• pp.199-206
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• 1995

This study is aimed to clarify on the influence of cultivated conditions and fungicides on development of Rhizoetonia diseases of zoysiagrass and creeping bentgrass and results are as follows. Infection rates of disease were observed more serious when inoculum amounts were higher than low. Effects of the watering intervals on the severity of disease with artificial inoculating conditions, infection rates were higher when two days watering interval for creeping bentgrass and one day interval for zoysiagrass. Disease severity of creeping bentgrass incited by Rhizoetonia solani AG 1 (1A) was grater under conditions of double amounts of nitrogen fertilization. A posi- tive correlation was founded between the pH and disease development. The pots with pH 5 and 8 were significantly more diseased grass than those in which the pH was in 6.5. Mepronil and myclobutanil were extremely effective against brown patch of creeping bentgrass and large patch of zoysiagrass and followed by capro, and tebeonazole. Fenari was inferior effect to both diseases.

• Preventive Nutrition and Food Science
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• 제13권4호
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• pp.306-312
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• 2008

This study investigated the influence of pH on the color development of melanoidins formed from amino acid enantiomer model systems. For this, the color development was evaluated by measuring browning at 420 nm and color measurements by spectrophotometry and colorimetry. The browning and browning index showed no difference according to the type of amino acid enantiomers, while that formed from the D-Asn system was the only difference according to pH level. The tristimulus value of melanoidins formed from all model systems was located on a dominant wavelength of 475 nm, the blue zone of the diagram. In addition, the $L^*$, $a^*$, $b^*$, $C^*_{ab}$ values, and ${\Delta}E^*$ index on the basis of the type of amino acid enantiomers, the differences were markedly found at pH 4.0. At pH 7.0, significantly differences were found in the $L^*$, $a^*$, $b^*$ values, and ${\Delta}E^*$ index and not in the case of the lysine enantiomers. In addition, at pH 10.0, the differences were found in the $a^*$ and $b^*$ values from the lysine enantiomers and $C^*_{ab}$ value from the asparagine enantiomers. Therefore, the color development of melanoidins was influenced by the type of amino acid enantiomers and pH levels. Especially, it is thought that the $a^*$ and $b^*$ values can be used to explain the differences among the amino acid enantiomers in the color development of melanoidins.

• 한국식품과학회지
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• 제22권5호
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• pp.543-548
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• 1990

살구의 휘발성 향기성분 조성에 대한 분리 방법의 영향을 조사코저 살구 과육(pH 3.1)을 simultaneous distillation-extraction(SDE)법, headspace trapping법 또는 이를 pH 7.0으로 중화시킨 후 SDE법에 의해 얻어진 정유성분의 조성을 분석 비교하였다. GC-MS 및 GC에 의한 표준품과 머무름 시간의 비교에 의해 확인된 80종의 성분들 중 pH3.1에서 SDE법에 의해 얻어진 정유성분중에는 다른 두 가지 방법에 의해 얻어진 정유성분에서는 검출되지 않거나 또는 미량으로 검출된 n-hexanal, trans-2-hexenal, cis-3-hexen-1-ol, linalool oxide, linalool, ${\alpha}-terpineol$, nerol, geraniol, benzyl alcohol, ${\beta}-phenylethyl alcohol$ 및 naphthalene 유도체들이 많이 검출되었으며 이러한 결과는 살구에서 비휘발성인 glycoside 형태로 존재하는 위와 같은 성분들이 산성조건하에서 수증기 증류시 glycoside 결합이 가수분해되어 휘발성 성분으로 유리되는데 기인하는 것으로 판단되었다.

• 한국물환경학회지
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• 제23권2호
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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.

• 한국세라믹학회지
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• 제40권12호
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• pp.1208-1212
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• 2003

CaCO$_3$ powders were synthesized by aqueous solution reaction of CaC1$_2$ㆍ2$H_2O$-(NH$_4$)$_2$CO$_3$ system with NH$_4$OH at 45$^{\circ}C$ and pHs 8, 9, 10, and 11 and in the concentration range of 0.1∼5 M and its polymorphism, morphology and size were investigated. In order to investigate the influence of pH on nucleation, pH was adjusted before and after reaction respectively. When pH was adjusted after reaction a formation ratio of vaterite was increased with increasing pH and concentration but vaterite was formed with calcite. But, when pH was adjusted before reaction, the formation rate of vaterite was increased with increasing pH and concentration. resulting in a phase-pure vaterite with a spherical shape and 2∼5 $\mu\textrm{m}$ in size. It was found that solubility of alkaline vaterite was decreased with increasing OH- ions in the high pH solution. When pH was adjusted before nucleation in the high concentration range, in particular, decreasing of solubility disturbed transformation of initially formed numerous vaterite to calcite.

• 한국토양비료학회지
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• 제26권4호
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• pp.225-229
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• 1993

ammonium thiosulfate(ATS)의 urease 활성 억제제로서의 효과를 thiourea와 비교하고, 온도 및 pH가 ATS의 효과에 미치는 영향을 실험한 바, 그 결과를 요약하면 다음과 같다. 1. ATS의 요소 가수 분해 저해율은 $25^{\circ}C$에서 요소의 5% 수준으로 처리하였을 때에는 1.5~14.3%, 10% 처리시에는 7.6~20.5%였다. 이는 thiourea의 저해율보다 다소 낮은 수준이었다. 2. ATS의 효과는 고온보다는 저온에서 뚜렷하게 나타났다. 즉 요소의 10% 수준으로 처리하였을 때 $10^{\circ}C$와 $15^{\circ}C$에서의 가수 분해 저해율은 각각 62.6%와 41.7%였다. 3. 토양 pH에 따라서 ATS의 효과가 나타나기 시작하는 시간이 달랐다. 즉 pH가 6.0과 6.5에서는 24시간부터 저해 효과가 나타난 반면, 5.0과 7.0, 7.5에서는 48시간부터 효과가 나타났다. 처리후 72시간에 urease 활성 저해율은 pH에 관계없이 비슷하므로, pH와 저해 효과와는 일정한 경향성이 없는 듯하다.

• Food Science and Biotechnology
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• 제17권2호
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• pp.324-329
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• 2008

The effect of ultra-high pressure homogenization on the emulsifying properties of whey protein was investigated in a model emulsion made with whey protein isolate and soya oil under various pH. The emulsifying properties, the average diameter of the oil droplets ($d_{vs}$), and the protein load, were measured for each emulsion produced at different homogenization pressures (50 to 200 MPa) and pH values (4.6 to 8.0). According to the results of variance analysis and response surface, the pH had more influence on oil droplet size and protein load than homogenization pressure. The model equations, which were obtained by response surface analysis, show that pH and homogenization pressure had the major effect on oil droplet size and protein load. Higher homogenization pressure decreased the average droplet size and the protein load. Homogenization at high pressure, as opposed to low pressure, causes no overprocessing, but the effect was pH-dependent. The average diameter of the oil droplets increased slightly by decreasing the pH from 8.0 to 6.5 and then increased dramatically toward the isoelectric point of whey protein (i.e., at pH 4.6). Moreover associated droplets were found at acidic pH and their size was increased at high temperature.

• 한국양식학회지
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• 제12권2호
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• pp.155-161
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• 1999

In order to obtain the basic information for seeding production of Echiuroid worm, Urechis unicinctus, the influence of pH and salinity on egg development was investigated. Mature adult of U. unicinctus were collected at the Diving Cooperation of Yosu in Korea and reared during 5 weeks. We carried out the artificial insemination in the laboratory on Dec. 29, 1998, and reared the embryo under different pH and salinity. Treatments were carried out with different pH(4~10) and salinity($0~45\textperthousand$). Embryos in pH 4, salinity $0\textperthousand$, $10\textperthousand$, $40\textperthousand$ and $45\textperthousand$ tanks did not develope after fertilization and became deformed or dead, before swimming embryo. In these pH and salinity conditions, deformation rate of embryo was high at 8-cell stage and 16-cell stage. But embryos in pH 5~10, salinity $20~35\textperthousand$ tanks developed into swimming embryo stage. These result indicate that an echiuran inhabits in both intertidal and subtidal mudflates. After fertilization, sixteen-cell stage took 5.3~5.6 hours in pH 5~10 tanks, and 5.1~5.8 hours in $20~35\textperthousand$ tanks. And swimming embryo took 13.3~ 14.1 hours in all conditions. The desirable pH and salinity for egg development were 7~8 and $30\textperthousand$, respectively.