• Title/Summary/Keyword: pH ranges

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Kinetic Studies on the Mechanism of Hydrolysis of 2-Phenyl-4H,5H-3-methyl-3-thiazolinium Perchlorate Derivatives (2-Phenyl-4H,5H-3-methyl-3-thiazolinium Perchlorate 유도체의 가수분해 반응 메카니즘에 관한 반응속도론적 연구)

  • Kim, Tae-Rin;Lee, So-Young;Han, Man-So;Pyun, Sang-Yong;Lee, Seok-Hee
    • Journal of the Korean Chemical Society
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    • v.44 no.2
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    • pp.120-126
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    • 2000
  • The rate constants for the hydrolysis of 2-phenyl-4H,5H-3-methyl-3-thiazolinium perchlorate(PTP) derivatives were detemined by the use of ultraviolet visible spectrophotometer in water. The rate equations which could be applied over a wide pH ranges were obtained. On the basis of rate equation, hydrolysis product analysis, general base catalysis, and substituent effect, a plausible mechanism of the hydrolysis is proposed: Below pH 4.0, the reaction is initiated by addition of water, while above pH 9.0, Michael type nucleophilic addition takes place. In the pH range of $4.5{\sim}8.0$, these two reactions appear to occur competitively.

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Environmentally Friendly Phytal Animal Removal for Re-use of Holdfasts of Sargassum fusiforme (Harvey) Setchell: pH and Salinity (갈조류 톳의 포복지 재활용을 위한 친환경적 해적생물 구제: pH와 염분)

  • Hwang, Eun Kyoung;Yoo, Ho Chang;Kim, Se Mi;Yoo, Hyun Il;Baek, Jae Min;Park, Chan Sun
    • Korean Journal of Environmental Biology
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    • v.32 no.4
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    • pp.306-310
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    • 2014
  • The brown seaweed Sargassum fusiforme is an edible and highly valued in Korea. During the summer season, phytal organisms graze heavily on young algal blades and holdfastsof the species and substantially reduce harvestable biomass. Here, in this study, we investigated the effects of pH (range: 2~13) and salinity (range: 0~44 psu) on the removal of two major phytal animals, Caprella scaura and Gammaropsis utinomi, associated with S. fusiforme. We also examined the optimum quantum yield (Fv/Fm) of algae in the same experimental conditions to quantify the tolerance of algae to acid and salinity treatments. It was observed that the phytal animals showed more than 80% mortality at pH lower that pH 4 and the extreams of salinity (0~10 psu and 44 psu) after a 5 min of immersion. However, the quantum yield of S. fusiforme was not significantly different from controls within the pH 3~11 range, and the 0~44 psu salinity range. Precisely, if the pH and salinity conditions outside these ranges were used in comercial Sargassum culture, the removal of the animal species would be higher, but with reduced quantum yield of algae. Taken together, our study results indicated that the pH and salinity treatments could allow multiple harvests from the same holdfast of S. fusiforme.

Radiation effects of I-V characteristics in MOS structure irradiated under $Co^{60}-{\gamma}$ ray ($Co^{60}-{\gamma}$ ray을 조사시킨 MOS 구조에서의 I-V특성의 방사선 조사 효과)

  • Kwon, S.S.;Jeong, S.H.;Lim, K.J.;Ryu, B.H.;Kim, B.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1992.11a
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    • pp.123-127
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    • 1992
  • When MOS devices is exposed to radiation, radiation effects of P-type MOS capacitor can cause modulation and/or degradation in devices characteristics and its operating life. The oxide layer is grown in $O_2$+T.C.E. and its thickness ranges from 40 to 80 nm. Irradiations on MOS capacitor were performed by Cobalt-60 gamma ray source and total dose ranges from $10^4$ to $10^8$ rads. The radiation effect on electrical conduction characteristics(I-V) in MOS capacitor was measured as a function of gate oxide thickness and total dose. From the experimental result, I-V characteristics is found to be influenced strongly by total dose in irradiated p-type MOS capacitors. The ohmic current is dependant on of total dose in irradiated P-type MOS capacitors. This results are explained using surface states at interface radiation-induced traps.

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Ionic Equilibria Analysis of $NiCl_2$ in Chloride Solutions by Using Bromley Equation (염산용액에서 Bromley식을 이용한 염화니켈의 이온평형해석)

  • Lee Man-Seung;Lee Gwang-Seop
    • Resources Recycling
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    • v.12 no.3
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    • pp.38-45
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    • 2003
  • ionic equilbria of nickel chloride in hydrochloric acid solutions were analyzed by considering chemical equilibria, mass and charge balance equations. The activity coefficients of solutes were calculated by using Bromley equation. It was found that most of species containing nickel existed as $Ni^{2+}$$NiCl^{+}$. The mole fractions of nickel hydroxides were very low in the con-centration ranges considered in this study and the mole fraction of$Ni_4$ $(OH)_{4}^{4+}$ increased greatly with the pH of the solution. The pH values of $NiCl_2$ $-HCl-NaOH-H_2$O system at $25^{\circ}C$ calculated in this study agreed well with those experimentally measured up to ionic strength of 9.4m.

Effects of pH and Salinity on the Cultivated Brown Alga Sargassumfulvellum and Associated Animals (갈조류 양식 모자반(Sargassum fulvellum)과 해적생물에 대한 pH와 염분의 효과)

  • Hwang, Eun-Kyeong;Ha, Dong-Soo;Baek, Jae-Min;Wee, Mi-Young;Park, Chan-Sun
    • ALGAE
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    • v.21 no.3
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    • pp.317-321
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    • 2006
  • The effects pH and salinity on the brown alga Sargassum fulvellum were investigated in the context of the removal of two major associated animals, Caprella scaura and Gammaropsis utinomi. Optimum quantum yield (Fv/Fm) of S. fulvellum was also examined in the same experimental conditions as an index of stress. Experiments on pH and salinity tolerances of the two animal species indicated that mortality was more than 80% at extremes of pH (2, 3, 4, 10, 11, 12) and salinity (0, 3.5, 7, 10, 44 psu) after a 5 min treatment. Lethal time (LT50) from pH 2 to pH 4 was less than 90 sec in C. scaura, and less than 70 sec in G. utinomi. From 0 to 10 psu, LT50 was less than 20 sec in C. scaura and less than 60 sec in G. utinomi. The quantum yield of S. fulvellum was not significantly different from controls within the pH range 4~10, and within the salinity range of 7-40 psu. When exposed to pH and salinity conditions outside these ranges, the effect of these factors on the removal of two animal species was higher, but quantum yield was highly reduced. These results indicate that the optimal conditions for removing the animal species without affecting optimum quantum yield were pH 4-10, and salinities 7-10 psu and 44 psu.

Effect of Perforated PVC Underdrainage Pipe on Desalting of Plastic Film House Soils (시설재배지 유공관 암거배수에 의한 염류집적 경감효과)

  • Kim, Dae-Su;Yang, Jae E.;Ok, Yong-Sik;Yoo, Kyung-Yoal
    • Korean Journal of Soil Science and Fertilizer
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    • v.39 no.2
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    • pp.65-72
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    • 2006
  • Objective of this research was to remove the accumulated salts in the plastic film house soils by installing the perforated PVC (${\phi}10cm$) underdrainage pipes at 50 cm depth of soils with cultivating vegetables. Efficiency of the underdrainage pipes was assessed based on the changes of soil chemical properties such as pH, EC, and cations, and growth and yield parameters of the vegetables between the two treatments; the control and the underdrainage pipe treatments. The EC of the underdrainage pipes installed soils after two growing seasons were in the ranges of $1.42-2.88dS\;m^{-1}$ but those of the control were in the ranges of $3.86-4.53dS\;m^{-1}$, indication the underdrainage pipes effectively removed the accumulated salts in soils. The pHs of the control soils and the underdrainage pipe installed soil were in the ranges of 7.2-7.5 and 6.9-7.3, respectively. There was a significant correlation between pH and cation exchange capacity (CEC) of the soils ($CEC=17.107{\times}pH-106.2$, $r^2=0.759$, P < 0.05). The ECs of the soils at different depths were compared between the two treatments after cultivating vegetables with lettuce-lettuce-garland chrysanthemum rotation systems. The ECs of the control soils at depths of 0-10, 10-20, 20-30, 30-40, and 40-50 cm were 3.45, 3.47, 3.03, 2.03, and $2.28dS\;m^{-1}$, respectively, with decreasing with soil depths. On the other hand, the respective ECs of the underdrainage pipes installed soils were 2.43, 2.52, 2.28, 4.00, and $4.23dS\;m^{-1}$ with increasing with soil depths. This might be derived from the salts moved downward with the draining water into the subsoil. The order of cations moved downward was Mg > Ca > K, based on the ratios of cations at specific depth over those at the surface soil. The survival rates of lettuce after 15 days of transplanting in the underdrainage pipe installed soils were 98.2% as compared to 86.6% of the control. The underdrainage pipe treatment also increased the diameter of the lettuce stalk from 12.9mm of the control to 13.7mm. Overall results demonstrated that the installment of the underdrainage pipes in the subsoils of the salt accumulated plastic film house soil effectively removed the salts by leaching downward,resulting in lowering soil EC and enhancing the growth and yield of vegetables.

pH-dependent Cytotoxicity of a Peptide Toxin, Tolaasin (펩티드 독소 Tolaasin에 의한 세포독성의 pH 의존성)

  • Kim, Sung-Tae;Choi, Tae-Keun;Kim, Young-Kee
    • Applied Biological Chemistry
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    • v.50 no.4
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    • pp.257-261
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    • 2007
  • Tolaasin, a peptide toxin produced by Pseudomonas tolaasii, causes a serious disease on the cultivated mushrooms, known as brown blotch disease. Hemolysis using red blood cells was designed to measure the cytotoxicity of tolaasin molecules. Since tolaasin has two amine groups near the C-terminus, its membrane binding will be dependent on the ionic states of the amine groups. When the tolaasin peptide was titrated, its titration curve indicated the presence of titratable amine(s) at pH ranges from 7.0 to 9.6. When the pH-dependence of tolaasin-induced hemolysis was measured at various pHs, hemolysis was more efficient at alkaline pHs. In order to measure the membrane binding activity of tolaasin at different pHs, RBCs were incubated with tolaasin molecules for short time periods and washed out with fresh buffer. Because of the tolaasin binding during the preincubation period, fast hemolyses were observed at pH 8 or higher. These results imply that non-charged or less positively charged states of tolaasin molecules easily bind to membrane and show high hemolytic activity.

Effect of pH on PAH Transport in Brush Border Basolateral Membrane Vesicles of Rabbit Proximal Tubule (가토 신장 근위세뇨관의 Brush Border 및 Basolateral Membrane Vesicle에서 PAH 이동에 미치는 pH의 영향)

  • Kim, Yong-Keun;Woo, Jae-Suk;Lee, Sang-Ho
    • The Korean Journal of Physiology
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    • v.22 no.2
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    • pp.281-293
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    • 1988
  • The effect of pH on the rate of PAH uptake was studied in rabbit renal basolateral membrane vesicles (BLMV) and brush border membrane vesicles (BBMV). In the absence of Na in incubation medium, a decrease in external $pH(pH_0)$ led to an increase in probenecid-sensitive PAH uptake by BLMV. In the presence of Na, the probenecid-sensitive PAH uptake was unaltered when the $pH_0$ decreased from 8.0 to 6.0 but further decrease in $pH_0$ to 5.5 increased significantly the uptake. The probenecid-sensitive PAH uptake was not affected by an alteration in pH per se in the absence of a pH gradient with or without the presence of Na. However, the presence of Na stimulated the probenecid-sensitive PAH uptake in all pH ranges tested over that measured in the absence of Na. A similar pattern of pH dependence on the PAH uptake was observed in BBMV but the presence of Na did not alter the probenecid-sensitive PAH uptake in the presence and absence of a pH gradient. Kinetic analysis for BLMV showed that Na or pH gradient increased Vmax of the probenecid-sensitive PAH uptake without a change in Km value. These results suggest that PAH is transported by $OH^-/PAH$ exchange process in the luminal membrane, but the pH dependence in the BLMV is not unequivocally consistent with an anion exchange process. The PAH transport is dependent on Na in BLMV but not in BBMV.

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Effects of Activated Carbon Particle Sizes on Caffeine Adsorptions (활성탄 입자 크기가 카페인 흡착에 미치는 영향)

  • Kim, Tae-Yang;Do, Si-Hyun;Hong, Seong-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.29 no.3
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    • pp.407-414
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    • 2015
  • The effect of activated carbon particle diameter (i.e. US sieve No. $8{\times}10$ ($d_p{\approx}2.19mm$), $18{\times}20$ ($d_p{\approx}0.92mm$), $50{\times}60$ ($d_p{\approx}0.27mm$) and $170{\times}200$ ($d_p{\approx}0.081mm$) on caffeine adsorption is investigated. BET surface area was increased with decreasing particle diameter ($d_p$), and caffeine adsorption rates increased with decreasing $d_p$. Moreover, pseudo-second order model is predicted the experimental data more accurately than pseudo-first order model, and the fastest rate constant ($k_2$) was $1.7g\;mg^{-1}min^{-1}$ when $d_p$ was 0.081 mm. Surface diffusion coefficient (Ds) was decreased with decreasing $d_p$ based on the minimum sum of square error (SSE). Practically, certain ranges of Ds are acceptable with high reliability ($R^2$) and it is determined that the effect of $d_p$ on Ds is unclear. The effect of pH on caffeine adsorption indicated the dependency of m/L ratio (mass liquid ratio) and $pH_{pzc}$. The $pH_{pzc}$ (i.e. $7.9{\pm}0.2$) was not affected by $d_p$. The higher caffeine adsorption at pH 4 and pH 7 than at pH 10 is due to $pH_{pzc}$, not $pk_a$ of caffeine.

Growth Inhibition of Cucumber by Absorbing Excess Al at Low Soil pH (강한 산성토양에서 Al의 과잉 흡수에 의한 오이 생육장해 양상)

  • Kim, Yoo-Hak;Kim, Myung Sook;Kang, Seong Soo;Lee, Hyeong Yong
    • Korean Journal of Soil Science and Fertilizer
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    • v.45 no.6
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    • pp.925-927
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    • 2012
  • On-site diagnosis applied to soil having a symptom of yellowing and whitening in cucumber leaf and stem. Soil pH determined 4.2 by methods of on-site analysis and 4.5 by soil test analysis. High aluminum in soil solution extracted with water saturation was detected. Leaf and stem tissue were abundant in Al content but not in Ca. Also, N content of leaf and stem was low compared to normal N ranges. This symptom of cucumber assumed to be from the Al and nitrous acid gas toxicity by low soil pH and Eh. Conclusionally, symptom in leaf and stem of cucumber was alleviated and cucumber normally recovered during cultivation period by applying calcium hydroxide solution to correct soil pH up to 6.5. These results showed that low soil pH resulted in aluminum toxicity and N deficiency to plant growth in on-site farming.