• Journal of Microbiology and Biotechnology
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• v.6 no.6
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• pp.391-396
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• 1996

The Gram-negative marine bacterium Marinomonas vaga, which requires 0.5 M NaCl concentration for optimal growth, is slightly halophilic. The growth of M vaga was highly resistant to the proton conductor, carbonyl cyanide m-chlorophenylhydrazone (CCCP) under alkaline pH conditions (pH 8.5) but very sensitive to CCCP under acidic pH conditions (pH 6.5). These results suggest that the respiratory chain-linked NADH oxidase system of M. vaga may lead to generation of a $Na^{+}$ electrochemical gradient. In order to examine the existence of $Na^{+}$-stimulated NADH oxidase in M. vaga, membrane fractions were prepared by the osmotic lysis method. The membrane-bound NADH oxidase oxidized both NADH and deamino-NADH as substrates and required $Na^{+}$ for maximum activity. The maximum activity of NADH oxidase was obtained at about pH 8.5 in the presence of 0.2 M NaCl. The site of $Na^{+}$-dependent activation in the NADH oxidase system was at the NADH:quinone oxidoreductase segment. The NADH oxidase and NADH:quinone oxidoreductase were very sensitive to the respiratory chain inhibitor, 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) in the presence of 0.2 M NaCl but highly resistant to another respiratory inhibitor, rotenone. Based on these findings, we conclude that M. vaga possesses the $Na^{+}$-dependent NADH:quinone oxidoreductase that may function as an electrogenic $Na^{+}$ pump.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1437-1439
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• 1995

This paper investigates the effect of thermal oxidation on the profile of the residual stress along the depth of p+ silicon films by quantitative determination method. Two examples for the application of this method illustrate that most of p+ region is subjected to the tensile stress except the region near the front surface and that the stress gradient of the film oxidized at $1100^{\circ}C$ is more steep than that of the film oxidized at $1000^{\circ}C$.

• The Korean Journal of Physiology
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• v.22 no.2
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• pp.307-318
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• 1988

Properties of succinate transport were examined in basolaterat membrane vesicles (BLMV) isolated from rabbit renal cortex. An inwardly directed $Na^+$ gradient stimulated succinate uptake and led to a transient overshoot. $K^+,{\;}Li^+,{\;}Rb^+$ and choline could not substitute for $Na^+$ in the uptake process. The dependence of the initial uptake rate of succinate on $Na^+$ concentration exhibited sigmoidal kinetics, indicating interaction of more than one $Na^+$ with transporter Hill coefficient for $Na^+$ was calculated to be 2.0. The $Na^+-dependent$ succinate uptake was electrogenic, resulting in the transfer of positive charge across the membrane. The succinate uptake into BLMV showed a pH optimum at external pH $7.5{\sim}8.0$, whereas succinate uptake into brush border membrane vesicles (BBMV) did not depend on external pH. Kinetic analysis showed that a Na-dependent succinate uptake in BLMV occurred via a single transport system, with an apparent Km of $15.5{\pm}0.94{\;}{\mu}M$ and Vmax of $16.22{\pm}0.25{\;}nmole/mg{\;}protein/min$. Succinate uptake was strongly inhibited by $4{\sim}5$ carbon dicarboxylates, whereas monocarboxylates and other organic anions showed a little or no effect. The succinate transport system preferred dicarboxylates in trans-configuration (furmarate) over cis-dicarboxylates (maleate). Succinate uptake was inhibited by the anion transport inhibitors DIDS, SITS and furosemide, and $Na^+-coupled$ transport inhibitor harmaline. These results indicate the existence of a $Na^+-dependent$ succinate transport system in BLMV that may be shared by the other Krebs cycle intemediates. This transport system seems to be very similar to the luminal transport system for dicarboxylates.

• The Korean Journal of Zoology
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• v.28 no.1
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• pp.31-43
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• 1985

The $(Ca^{2+}+Mg^{2+})$-ATPase has been purified homogeneously from sarcoplasmic reticulum of rat skeletal muscle by sucrose density gradient centrifugation. The purified enzyme has a molecular weight of 115,000 as judged by polyacrylamide gel electrophoresis in the presence of sodium dedecyl sulfate, and therefore has the same size of the enzyme in rabbit and chick skeletal muscle. $Ca^{2+}, Mg^{2+}, Fe^{2+}, Co^{2+}, and Mn^{2+}$ at 50 $\\muM$ show stimulatory effect on the ATP-ase, while $Zn^{2+}, Cu^{2+}, and Hg^{2+}$ inhibit it at the same concentration. The ATPase activity is insensitive to antimalarial drugs such as quinine and quinacrine, but is sensitive to inhibition by p-hydroxymecurie benzoate and phenylmethylsulfonylfluoride. The enzyme has optimum pH of 6 to 7 and Km value for ATP is estimated to be 98 $\\muM$. Thus, a number of biochemical properties of this enzyme appear to be different from those of the enzyme that have been isolated from rabbit skeletal muscle. The $(Ca^{2+}+Mg^{2+})$-ATPase appears to be selectively degraded in microsomal fraction. The activity of metalloendoprotease is evident in the microsomal preparation when assayed by radioactively labeled protein substrate, such as $^{3}H-casein and $^{125}I$-insulin. However, it is presently unclear whether the metalloendoprotease is responsible for the degradation of the $(Ca^{2+}+Mg^{2+})$-ATPase.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.1
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• pp.21-26
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• 2002

Effects of cadmium (Cd) intoxication on renal endosomal accumulation of organic cations $(OC^+)$ were studied in rats using $^{14}C-tetraethylammnium$ (TEA) as a substrate. Cd intoxication was induced by s.c. injections of 2 mg Cd/kg/day for $2{\sim}3$ weeks. Renal cortical endosomes were isolated and the endosomal acidification (acridine orange fluorescence change) and TEA uptake (Millipore filtration technique) were assessed. The TEA uptake was an uphill transport mediated by $H^+/OC^+$ antiporter driven by the pH gradient established by $H^+-ATPase.$ In endosomes of Cd-intoxicated rats, the ATP-dependent TEA uptake was markedly attenuated due to inhibition of endosomal acidification as well as $H^+/TEA$ antiport. In kinetic analysis of $H^+/TEA$ antiport, Vmax was reduced and Km was increased in the Cd group. Inhibition of $H^+/TEA$ antiport was also observed in normal endosomes directly exposed to free Cd (but not Cd-metallothionein complex, CdMt) in vitro. These data suggest that during chronic Cd exposure, free Cd ions liberated by lysosomal degradation of CdMt in proximal tubule cells may impair the endosomal accumulation of $OC^+$ by directly inhibiting the $H^+/OC^+$ antiporter activity and indirectly by reducing the intravesicular acidification, the driving force for $H^+/OC^+$ exchange.

• The Journal of the Korean Society for Microbiology
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• v.34 no.5
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• pp.423-433
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• 1999

A novel bacteriophage, designated as VPP97, that infects the strains of Vibiro parahaemolyticus (hallophilic, Gram-negative bacterium) isolated most commonly from marine environments, has been discovered, and several of its properties have been determined. The plaques were clear and sized $0.6{\sim}1.0\;mm$ in diameter. The virion forms a single band on 70% sucrose gradient and ${\rho}1.50$ CsCl gradient by sucrose gradient centrifugation and CsCl gradient centrifugation respectively. It has a hexagonal head and a relatively long tail, as shown by electron microscopy. Vibrio alginolyticus, Vibrio fluvialis and Vibrio furnissii were also sensitive to this phage. It was almost totally inactivated at $70^{\circ}C$ and at pH below 5 or over 10. The nucleic acid of VPP97 is composed of DNA. The VPP97 had 9 specific structural proteins sized between 21.5 kDa and 97.4 kDa on SDS-PAGE. When V. parahaemolyticus cultures were treated with either phage VPP97 or one of the several antibiotics for 2 hours, the viable number of V. parahaemolyticus treated with the phage VPP97 is lower than that treated with chloramphenicol, erythromycin or penicillin, but not lower than that treated with tetracycline. Mice that have responded to the phage treatment revealed the lower numbers of V. parahaemolyticus in small intestine and less damage on small intestine compared to the untreated mice. Therefore, we suggest that the phage treatment appears effective to the infection by V. parahaemolyticus.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.137-147
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• 1994

This study was designed to identify and quantitate airborne isocyanate simultaneously by HPLC. These samples were collected using 1-(2-pyridyl)piperazine(1-2PP) coated glass fiber filter from polyurethane painting works at 8 wood furniture factories in Kimpo and Inchun. The results obtained were as follows : 1. The most suitable mobile phase condition of simultaneously analyzing isocyanates was 0.01 M ammonium acetate buffer ACN(70/30) adjusted to pH 6.2 from the beginning of the analysis to 20 min and 0.01 M ammonium acetate buffer/ACN(50/50) adjusted to pH 6.2 from 21 min to 40 min using the gradient mode. The peaks of isocyanates were able to obtain within 30 min. 2. The recovery efficiencies for 2,6-TDI, 2,4-TDI, HDI and MDI urea derivates spiked at the target concentration on coated glass fiber tillers were 91.00, 93.42, 91.31 and 94.21 %, respectively. 3. The qualitative analysis of the isocyanates samples from polyurethane spray painting works in wood furnture factories identified Ihree isocyanates, 2,6-TDI, 2,4-TDI and MOI. And their concentration ranges were 0-312.6, 0-56.3 and $0-62.1{\mu}g/m^3$, respectively. A disadvantage of using the colorimetric method for isocyanate analysis is its inability of separating isocyanates. This study identified such three isocyanates as 2,6-TDI, 2,4-TDI and MDI from polyurethane spray painting works in wood furniture factories. These isocyanates were successfully quantitated by HPLC by modifying the mobile phase condition and switching to gradient mode.

• Journal of the Korean Mathematical Society
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• v.39 no.5
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• pp.783-800
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• 2002

Let B denote the unit ball in $C^n$, and ν the normalized Lebesgue measure on B. For $\alpha$ > -1, define $dv_\alpha$(z) ＝ $c_\alpha$$(1-\midz\mid^2)^{\alpha}$dν(z), z $\in$ B. Here $c_\alpha$ is a positive constant such that $v_\alpha$(B) ＝ 1. Let H(B) denote the space of all holomorphic functions in B. For $p\geq1$, define the Bergman-Privalov space $(AN)^{p}(v_\alpha)$ by $(AN)^{p}(v_\alpha)$ = ${f\inH(B)$ : $\int_B{log(1+\midf\mid)}^pdv_\alpha\;<\;\infty}$ In this paper we prove that a function $f\inH(B)$ is in $(AN)^{p}$$(v_\alpha)$ if and only if $(1+\midf\mid)^{-2}{log(1+\midf\mid)}^{p-2}\mid\nablaf\mid^2\;\epsilon\;L^1(v_\alpha)$ in the case 1＜p＜$\infty$, or $(1+\midf\mid)^{-2}\midf\mid^{-1}\mid{\nabla}f\mid^2\;\epsilon\;L^1(v_\alpha)$ in the case p ＝ 1, where $nabla$f is the gradient of f with respect to the Bergman metric on B. This is an analogous result to the characterization of the Hardy spaces by M. Stoll [18] and that of the Bergman spaces by C. Ouyang-W. Yang-R. Zhao [13].

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.145-151
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• 2002

The effect of low pH on physiological changes was studied with the acidophilic green alga, Clamydomonas acidophila, UTCC 122. The growthrates (${\mu}$) were identical, $0.5{\sim}0.7\;day^{-1}$, at pH 3.7${\sim}$6.7 and no significantly different (ANOVA, p =0.134), showing cell volume reduced gradually as they were growing, whereas that at pH 2.7 was falling to zero and cell volume increased dramatically. Chlorophyll a concentration of the cultures incubated for one day was $191{\sim}255\;pg\;cell^{-1}$, after then it declined from $60{\sim}103\;pg\;cell^{-1}$ at pH 3.7${\sim}$6.7 except $210\;pg\;cell^{-1}$ at pH 2.7, which was directly related with cell volume. External carbonic anhydrase (CA) activity was varied from1.1 to$3.7{\times}10^{-4}\;E.U.\;mm^{-2}$, showing the gradualincrease during culture, except at 2.7 and pH 5.7. However there was not found any relationship among the pH gradient cultures. CA molecular mass of C. acidophila was 29 kBa, and concentration of that was identical in all cultures. The proteins of 41 kDa and 63 were not or very　faintly expressed in low pH cultures, in contrast that of 17 kDa more expressed. In this work, we found that C. acidophila could live optimally within a wide range of acidic pH, and 17 kDa of unidentified protein might be concerned with tolerating in low acid environment.

• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.49-57
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• 2002

During the electrokinetic remediation, direct current applied to a soil-water-electrolyte system derives the variations of fluid transport phenomena in soil-water system and soil-water interface characteristics. Therefore, these variations affect the electrokinetic reaction. In this study, lab-scale electrokinetic remediation tests were performed to characterize the electrical and chemical parameters variation in soil. During the test, voltage gradient, electrical current, zeta potential and pH variations were measured. On the basis of experimental results, computer modeling techniques predicting the variations of these parameters are suggested.