• Resources Recycling
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• v.27 no.6
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• pp.30-37
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• 2018

A series of experiment was conducted to evaluate basic performances of low-pH, anti-washing grouts incorporating gypsum which applied for reinforcing underwater cavities in limestone- grounds. Various types of mix proportions were designed and the fluidity, strength and environmental impact of these mixtures were evaluated. The flowability was evaluated under two conditions, i.e., flows without and with pressing, respectively. Strength was measured for the hardened mixtures fabricated under conditions of air and water injections. The environmental impacts including the pH of the suspension and the suspended solids concentration for the mixtures were evaluated. The low pH of fresh mixture suspension, below than 10, was achieved by incorporation of gypsum. The mix proportions of cement-quartz powder-gypsum binders and chemical agents resulted in mortar natural flow 7-10 cm and uniaxial compressive strength 4 MPa were derived.

• Journal of Plant Biology
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• v.19 no.4
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• pp.95-99
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• 1976

This work deals with different extraction media and reaction mixtures on photosystem II activity of Spinach chloroplasts. The photoreduction rate of ferricyanide and DPIP by intact chloroplasts which extracted with four kinds of extraction media; S-Tris-N pH 7.2, 8.0, S-Tricine-N pH 7.2, 8.0, was measured in five kinds of reaction mixtures; S-Tris-N pH 7.2, 8.0, S-Tricine-N pH 7.2, 8.0, 0.05 M-Tris pH 7.2. The extraction medium which shows the highest photoreduction rate was S-Tris-N at pH 7.2 and S-Tricine-N at pH 8.0. As to the reaciton mixture, S-Tricine-N pH 8.0 showed the highest rate. On the complex effects of extraction media and reaction mixtures, the highest photordeuction rate of Hill oxidant by intact chloroplasts was obtained by S-Tris-N pH 7.2 extraction medium and S-Tricine-N pH 8.0 reaction mixture. The second highest activity was obtained by S-Tricine-N pH 8.0 extraction medium and reaction mixture.

• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.1
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• pp.1-7
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• 1987

A pot experiment conducted to investigate the root elongation and weight of grasses, i.e. Orchardgrass, tall fescue and perennial ryegrass under the conditions adjusted pH of half vertical part of pot soil to seven levels from 2 to 8. 1. Root growth was drastically decreased as soil pH was lowed. 2. Higer the soil pH, longer the root length. Increase of soil pH to 6 increased the root length of orchardgrass, perennial ryegrass and tall fescue. 3. Regardless of grass species, most of roots distributed to the soil which adjusted pH from 6 to 7. 4. Dry weight of root was increased to pH 7 of soil in orchardgrass and perennial ryegrass and was 55 to 78% of production of pH 6 compared with soil pH 7. In case of tall fescue, dry root weight in the soil pH 7 was 69.8% of root weight growed in soil pH 6.

• Journal of Environmental Science International
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• v.16 no.7
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• pp.779-784
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• 2007

Dinitrophenol is preventing cells from making energy for growth and it has been suggested that pH may be important in mitigating effects of uncouplers. The effect of pH on toxicity of dinitrophenol at high concentration was investigated, over a pH range of 5.7 to 8.7. DNP inhibition was found to be strongly dependent on mixed liquor pH. The DNP degradation rate was highest in the pH range of 7.0 to 7.8; at pH 6.0 degradation of 0.41 mM dinitrophenol was significantly inhibited; at pH <5.7, dinitrophenol degradation was completely inhibited after approximately 25% of the dinitrophenol was degraded. However no significant effect of pH variation was seen on glucose uptake by the activated sludge mixed culture.

• 한국해양학회지
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• v.15 no.1
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• pp.62-65
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• 1980

1976년 7월부터 1979년 5월까지 3년간 진해만의 표층에서 격월로 식물성플랑크톤 군집 변화에 영향을 미치는 환경요인(수온, 염분도, pH, 투명도, 용존산소, Chlorophyll-a,c, NO$_{2}$-N 및 PO$_{4}$-P)에 대하여 조사했다. 9가지 환경요인이 식물성플랑크톤 군집 변화에 37.20% 영향을 미치고 있었으며 각각의 환경요인으로는 PO$_{4}$-P, 투명도, Chlorophyll-a, 수온, 염분도 등이 중요한 요인이었으며 용존산소, NO$_{2}$-N, pH 및 Chlorophyll-c 는 크게 영향을 미치지 않고 있었다.

• Proceedings of the KAIS Fall Conference
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• 2002.05a
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• pp.264-266
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• 2002

원자력 발전소의 2차계통수에는 pH를 조절하여 부식을 억제하기 위해 pH제어제로 약염기성 화학물질을 첨가하고 있다. pH 제어제로 암모니아를 사용하였으나 pH가 낮아 부식생성물이 생성되어 증기발생기의 전열관에 슬러지의 퇴적으로 전열관의 부식이 촉진되므로 pH 제어제를 에탄올아민으로 바꿈으로 슬러지의 생성 및 이동을 억제하고 있다. 그러나 에탄올아민은 암모니아와 물리화학적 성질이 다르므로, 증기발생기에 유입되는 부식생성물의 용해와 흡착, 이온성 불순물의 잠복현상에 미치는 영향이 다르다. 본 연구는 암모니아와 에탄올아민이 온도가 점차 높아짐에 따라 부식생성물에 대찬 용해와 흡착, 이온성불순물의 잠복현상에 미치는 영향을 조사하였다. 이 실험의 결과로 2차 계통수의 pH 제어제는 ETA가 암모니아보다 증기발생기 슬러지의 철산화물에 더 흡착되어 더 많이 용해되어 퇴적된 슬러지 양을 감소시키므로, 슬러지에 흡착된 불순물의 양을 감소시저 잠복 현상을 억제할 것으로 조사되었다.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.375-380
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• 2003

This study was carried out 1) to investigate the pH effect on solubilization of phenanthrene by biosurfactant in aqueous system and 2) to evaluate the pH effect on the biodegradation rate of phenanthrene in the presence and the absence of the biosurfactant by phenanthrene degraders. Tween 80, which is a chemically synthesized surfactant, showed greater solubilizing capacity than rhamnolipid. The solubilization capacity can be expressed as a MSR(molar solubilization ratio=moles of organic compounds solubilized per mole of surfactant). The calculated MSR of Tween 80 and rhamnolipid were 0.1449 and 0.0425 respectively. The kinetic study of phenanthrene solubilization by rhamnolipid showed that solubilization mechanism could reach equilibrium within 24 hours. Addition of 240 ppm rhamnolipid solution, which concentration is 4.3 times of Critical Micelle Concentration(CMC), caused 9 times solubility enhancement compared to water solubility. The highest solubilities were detected around a pH range of 4.5-5.5. Changes in apparent solubility with the changes in pH are possibly related to the fact that the rhamnolipid, an anionic surfactant, can form different structures depending on the pH. Two biodegradation experiments were performed in the absence and the presence of rhamnolipid, with the cell growth investigated using a spread plate method. The specific growth rates at pH 6 and 7 were higher than at the other pH, and the HPLC analysis data, for the total phenanthrene loss, confirmed the trends in the $\mu$(specific growth rate) values. In presence of rhamnolipid, maximum $\mu$ values shifted from around pH 5 which showed maximum enhancement of solubility in the abiotic experiment, compared to the $\mu$ values obtained without the biosurfactant. In this study, the increase in the observed specific grow rate(1.44 times) was not as high as the increase in solubilization(5 times). This was supported by the fact all the solubilized phenanthrene is not bioavailable to microorganisms.

• KSBB Journal
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• v.10 no.5
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• pp.568-574
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• 1995

To investigate the effect of pH on organic acid production by Anaerobiospirillum succiniciproducens, an anaerobic fermentation was carried out by maintaining the pH of the fermentation broth at 5.8, 6.0, 6.4, 6.8, and 7.2. At various pHs, the concentrations of cell were $1.0∼1.9g/\ell$ which were two to three times higher than those of the other worker's results, and the maximum was obtained at pH 5.8. Substrate consumption was increased by increasing the pH in the range of pH 6.0 to 6.8, while the sugar consumption rate at both pH 5.8 and 7.2 was very slow. The total amount of 2M $Na_2C0_3$ added for adjustment of pH change due to organic acid production was maximum at pH 6.8. Changes of conductivity of the fermentation broth was very simillar to those of 2M $Na_2C0_3$ added at various pHs. Therefore, it is suggested that determination of the amount of organic acid in a broth can be possible by measuring the conductivity. The maximum production yield of lactate based on glucose was 64% for pH 7.2 and 32% for pH 6.8, respectively.

• Resources Recycling
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• v.25 no.6
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• pp.23-28
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• 2016

In this study, leaching process to extract phosphorus from the steelmaking slag was investigated for using the fertilizer resources of agriculture. In general, the phosphorus of steelmaking slag is formed as $C_2S-C_3P$ solid solution, and also, this solid solution is soluble in water more than the other phase in slag, and less than free CaO phase. In the present experiment, the influence of pH on the leaching behavior of various elements from the steelmaking slag was investigated by using multi-component steelmaking slag. When the pH was decreased, the concentration of Ca, Si, P and Fe in solution from the steelmaking slag was increased. Furthermore, at a pH of 3, the concentration of P ion in solution was decreased as leaching time increased. It is considered that the decrement of P was caused from the precipitation reaction between P ion and Fe ion in solution.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.760-765
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• 2013

Lysozyme crystallization was performed by using flow-focusing chip in droplet-based microfluidic system. Water-in-oil droplets were formed in the system and collected on petri-dish and cross type mold. Liquid-liquid reaction of lysozyme and sodium chloride occurred in the droplet and crystals were observed through microscope. Solution pH was varied as 4.8 and 7.2. Crystals of polyhedron and plate-like shape were obtained at pH 4.8, while needle structure crystals formed at pH 7.2. Lysozyme in single droplet for two pHs were crystallized with constant or decreased droplet size. However, crystals at pH 4.8 were only obtained in the droplet of which size was increased by the interaction between droplets. Droplet volume did not change at pH 7.2 and crystals formed in both droplets.