• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.4
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• pp.282-285
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• 2004

Kinetics of H-spillover over $Pt/MoO_3$ was greatly affected by the amount of residual chlorine differing by calcination temperature. Multifacetted techniques for characterization were dedicated to elucidate the faster reduction of chlorine in the isothermal reduction (ITR) at $50^circ{C}$ after calcination. Reduction of residual chlorine over Platinum resulted in opening the more channel of hydrogen pathway into more $MoO_3$ particles and controlling the kinetics of hydrogen uptake.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.119-130
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• 2006

As unialgal cultures to examine the growth kinetics of an algal species, Microcystis aeruginosa was grown in chemostats with nitrogen and phosphorus limitation. The nutrient concentrations of $NH_4\;^+\;and\;PO_4\;^{3-}$ to limit the growth of M, aeruginosa were approximately 200 ${\mu}M$ and 7 ${\mu}M$, respectively. Cell size of the algae decreased towards the $NH_4$-nitrogen limitation under a constant dilution rate, while it increased in the $PO_4$-limitaion. The cell quota of nitrogen under nitrogen-limited conditions was 6.1 ${\mu}mol$ mg $C^{-1}$ and, under nitrogen sufficient conditions, ranged from 9.5 ${\mu}mol$ mg $C^{-1}$ to 12.4 ${\mu}mol$ mg $C^{-1}$. In addition to the cell quota, the half-saturation constants for nitrogen uptake ($K_s$) and the growth rate (${\mu}_m$) was 36 ${\sim}$ 61 ${\mu}M$ and 0.28 ${\sim}$ 0.35 ${\mu}mol$ cell ${\cdot}$ $hr^{-1}$ to show high values in comparison with other algal species. As the limiting concentration, cell quota and uptake rate of M. aeruginosa were higher than those of any other species, the its nitrogen requirement would be great. In the other side, as the half saturation constant ($K_s$) for nitrogen uptake was higher, and the ratios ofmaximum uptake rate ($V_m$) and $K_s$ was relatively low, the species would have the low competitive ability in the low nitrogen concentration in the ambient water. However, the low concentration of nitrogen in the Nakdong River during the Microcystis outbreak would be the inevitable results of the algal blooms. In the lower Parts of the Nakdong River, the nutrient status was coupled with the growth kinetics of the blooming algae to have clear seasonal variations through a year.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.2
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• pp.137-146
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• 1999

Interactions among dexamethasone, dehydroepiandrosterone (DHEA), lipopolysaccharide (LPS), and antimycin A on the glutamate uptake and the polyamine uptake were investigated in primary cultures of rat cerebral cortical astrocytes to examine the effects of dexamethasone and DHEA on the regulatory role of astrocytes in conditions of increased extracellular concentrations of glutamate or polyamines. 1. $[^3H]Glutamate$ uptake: LPS and antimycin A decreased $V_{max},$ but both drugs had little effect on $K_m.$ Dexamethasone also decreased basal $V_{max}$ without any significant effect on $K_m.$ And dexamethasone further decreased the antimycin A-induced decrease of $V_{max}.$ DHEA did not affect the kinetics of basal glutamate uptake and the change by LPS or antimycin A. 2. $[^{14}C]Putrescine$ uptake: LPS increased $V_{max},$ and antimycin A decreased $V_{max}.$ They showed little effect on $K_m.$ Dexamethasone decreased $V_{max}$ of basal uptake and further decreased the antimycin A-induced decrease of $V_{max},$ and also decreased $V_{max}$ to less than control in LPS-treated astrocytes. DHEA did not affect $K_m$ and the change of $V_{max}$ by LPS or antimycin A. 3. $[^{14}C]Spermine$ uptake: Antimycin A decreased $V_{max},$ and LPS might increase $V_{max}.\;K_m$ was little affected by the drugs. Dexamethasone decreased basal $V_{max}$ and might further decrease the antimycin A-induced decrease of $V_{max}.$ And dexamethasone also decreased $V_{max}$ to less than control in LPS-treated astrocytes. DHEA might increase basal $V_{max}$ and $V_{max}$ of LPS-treated astrocytes. 4. $V_{max}$ of glutamate uptake by astrocytes was increased by putrescine (1000 ${\mu}M$ & 2000 ${\mu}M$) and spermidine (200 ${\mu}M,$ 500 ${\mu}M$ & 2000 ${\mu}M$). Spermine, 200 ${\mu}M$ (and 100 ${\mu}M$), also increased $V_{max},$ but a higher dose of 2000 ${\mu}M$ decreased $V_{max}.\;K_m$ of glutamate uptake was not significantly changed by these polyamines, except that higher doses of spermine showed tendency to decrease $K_m$ of glutamate uptake. In astrocytes, dexamethasone inhibited the glutamate uptake and the polyamine uptake in normal or hypoxic conditions, and the polyamine uptake might be stimulated by LPS and DHEA. Polyamines could aid astrocytes to uptake glutamate.

• Journal of Microbiology and Biotechnology
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• v.19 no.5
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• pp.447-454
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• 2009

The transport of spermidine into a cyanobacterium, Synechocystis sp. pec 6803, was characterized by measuring the uptake of $^{14}C$-spermidine. Spermidine transport was shown to be saturable with an apparent affinity constant ($K_m$) value of $67{\mu}M$ and a maximal velocity ($V_{max}$) value of 0.45 nmol/min/mg protein. Spermidine uptake was pH-dependent with the pH optimum being 8.0. The competition experiment showed strong inhibition of spermidine uptake by putrescine and spermine, whereas amino acids were hardly inhibitory. The inhibition kinetics of spermidine transport by putrescine and spermine was found to be noncompetitive with $K_i$ values of 292 and $432{\mu}M$, respectively. The inhibition of spermidine transport by various metabolic inhibitors and ionophores suggests that spermidine uptake is energy-dependent. The diminution of cell growth was observed in cells grown at a high concentration of NaCl. Addition of a low concentration of spermidine at 0.5 mM relieved growth inhibition by salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased spermidine transport with about 30-40% increase at 10 mosmol/kg upshift.

• Environmental Engineering Research
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• v.21 no.2
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• pp.203-210
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• 2016

Hybrid materials were obtained modifying the bentonite (BC) and local clay (LC) using hexadecyltrimethylammonium bromide (HDTMA) or the clay were pillared with aluminum followed by modification with HDTMA. The materials were characterized by the SEM, FT-IR and XRD analytical tools. The batch reactor data implied that the uptake of $17{\beta}$-estradiol (E2) by the hybrid materials showed very high uptake at the neutral pH region. However, at higher and lower pH conditions, slightly less uptake of E2 was occurred. The uptake of E2 was insignificantly affected changing the sorptive concentration from 1.0 to 10.0 mg/L and the background electrolyte (NaCl) concentrations from 0.0001 to 0.1 mol/L. Moreover, the sorption of E2 by these hybrid materials was fairly efficient since within 30 mins of contact time, an apparent equilibrium between solid and solution was achieved, and the data was best fitted to the PSO (pseudo-second order) and FL-PSO (Fractal-like-pseudo second order) kinetic models compared to the PFO (pseudo-first order) model. The fixed-bed column results showed that relatively high breakthrough volume was obtained for the attenuation of E2 using these hybrid materials, and the loading capacity of E2 was estimated to be 75.984, 63.757, 58.965 and 49.746 mg/g for the solids BCH, BCAH, LCH and LCAH, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.2
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• pp.114-117
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• 2004

Rates of $H_2$ uptake into $Pt/MoO_3$ were measured for the noncalcined and $200^{\circ}C$ calcined $Pt/MoO_3$. Amount of $H_2$ uptake for $200^\circ{C}$calcined $Pt/MoO_3$ was greater than the amount of noncalcined $Pt/MoO_3$. From these two experiments, it was found that the rates of $H_2$ desorption were proportional to the increase of desorption temperature. XPS demonstrated that Cl reduced more faster in ITR after calcination at $200^{\circ}C$. This inducd smaller amount of residual chlorine at adlineation sites between Pt and $MoO_3$ substrates. This resulted in opening the more channel of hydrogen pathway into more $MoO_3$particles and controled the kinetics of hydrogen uptake.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.11
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• pp.929-934
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• 2011

The adsorption kinetic study of ruthenium complex, N3, onto nanoporous titanium dioxide ($TiO_2$) photoanodes has been carried out by measuring dye uptake in-situ. Three simplified kinetic models including a pseudo first-order equation, pseudo second-order equation and intraparticle diffusion equation were chosen to follow the adsorption process. Kinetic parameters, rate constant, equilibrium adsorption capacities and related coefficient coefficients for each kinetic model were calculated and discussed. It was shown that the adsorption kinetics of N3 dye molecules onto porous $TiO_2$ obeys pseudo second-order kinetics with chemisorption being the rate determining step. Additionally the heterogeneous surface and the pore size distribution of porous $TiO_2$ adsorbents were also discussed.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.237-238
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• 1998

The kinetics of sulfite oxidation must be fast and the concentration of sulfite must be low to emulate oxygen uptake by blood. The kinetics were studied yielding a first order rate constant in sulfile, zero order in oxygen. Limitations of the technique were evaluated using the experimental rate constant and an adaptation of Lightfoot's approximation, while the reaction of hemoglobin is reversible and essentially instantaneous, that for sulfite is irreversible and finite. Thus if the approach to saturations not monotonic or if the mass transfer resistance is significantly lowered, e. g. when blood film thicknesses are thinner than a few hundred microns, deviations may occur.

• Journal of Microbiology and Biotechnology
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• v.21 no.6
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• pp.652-658
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• 2011

The growth kinetics of Streptomyces noursei NRRL 5126 was investigated under different aeration and agitation combinations in a 5.0 l stirred tank fermenter. Poly-${\varepsilon}$-lysine biosynthesis, cell mass formation, and glycerol utilization rates were affected markedly by both aeration and agitation. An agitation speed of 300 rpm and aeration rate at 2.0 vvm supported better yields of 1,622.81 mg/l with highest specific productivity of 15 mg/l.h. Fermentation kinetics performed under different aeration and agitation conditions showed poly- ${\varepsilon}$-lysine fermentation to be a growth-associated production. A constant DO at 40% in the growth phase and 20% in the production phase increased the poly-${\varepsilon}$-lysine yield as well as cell mass to their maximum values of 1,992.35 mg/l and 20.73 g/l, respectively. The oxygen transfer rate (OTR), oxygen utilization rate (OUR), and specific oxygen uptake rates ($qO_2$) in the fermentation broth increased in the growth phase and remained unchanged in the stationary phase.

• Textile Coloration and Finishing
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• v.8 no.6
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• pp.27-32
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• 1996

This research is to investigate the reaction kinetics by air-lift bioreactor using calcium hydroxide, the neutralization agent and immobilization media, for removing ethylene glycol remained after chemical pretreatment. It was found that the optimum hydraulic retention time was obtained as 24.2hours at the optimum F/M ratio of 1.32kg-$TCOD_{Mn}$/day.kg-MLVSS, and then, infiuent $TCOD_{Mn}$ and MLVSS concentration were 3,290mg/l and 2,472mg/l, respectively. During the steady state, the kinetics constants such as maximum specific substrate removal rate, half saturation velocity coefficient, yield coefficient and endogenous respiration coefficient were estimated in the base of $TCOD_{Mn}$ as substrate concentration. And they were 1.47day$^{-1}$, 3.95mg/l, 0.391 and 0.092day$^{-1}$, respectively. And also, the oxgen use coefficients for cell synthesis, a', and energy of maintenance, b', were obtained as 0.4kg-O$_{2}$/kg-$TCOD_{Mn}$ and 0.056day$^{-1}$, at the steady state by the experimental result of oxygen uptake rate.