• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.673-677
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• 2001

Pseudo-first-order rate constants have been measured spectrophotometrically for the reactions of 8-(5-nitroquinolyl) 3-furoate with alkali metal ethoxides in anhydrous ethanol. The plot of kobs vs the concentration of alkali metal ethox ides is linear for the reactions performed in the presence of a complexing agent, 18-crown-6 ether, but exhibits upward curvatures for the corresponding reactions performed in the absence of the complexing agent, indicating that the alkali metal ions in this study behave as catalysts. Second-order rate constants were determined for the reactions with dissociated free ethoxide (kEtO-) and with ion paired alkali metal ethoxides (kEtO-M + ) from ion pairing treatments. The magnitude of catalytic effect (kEtO-M + /kEtO-) was found to be 1.7, 3.4 and 2.5 for the reaction of 8-(5-nitroquinolyl) 3-furoate, while 1.4, 3.6 and 4.2 for that of 4-nitrophenyl 2-furoate, 1.8, 3.7 and 2.4 for that of 8-(5-nitroquinolyl) benzoate, and 2.0, 9.8 and 9.3 for that of 8-(5-nitroquinolyl) 2-furoate with EtO- Li+ , EtO- Na+ and EtO- K+ , respectively. A 5-membered chelation at the leaving group is suggested to be responsible for the catalytic effect shown by alkali metal ions.

• Analytical Science and Technology
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• v.8 no.1
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• pp.79-84
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• 1995

Ion-selective poly(vinyl chloride) membrane electrodes for the determination of the anticholinergic drug alverine in pure substances is described. Ion-pair complex of alverine with anionic counter ion acid red 97 is investigated as electroactive compound for the electrode membrane. On the optimal composition of membrane, its slope was 55.35mV/decade, relative standard deviation was 0.61 and lower limit of linear range was $1.0{\times}10^{-5}M$. The observed potentiometric selectivity coefficient was -2.625 toward methylephedrine and -2.216 toward histidine. We can got the stable potential at pH 7.0~4.0. Response time was 20~30 seconds for solutions${\leq}10^{-4}M$, about 10 seconds for solutions ${\geq}10^{-4}M$ of these compounds.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3543-3548
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• 2010

A kinetic study on nucleophilic displacement reactions of 2-pyridyl X-substituted benzoates 1a-e with potassium ethoxide (EtOK) in anhydrous ethanol is reported. Plots of pseudo-first-order rate constants ($k_{obsd}$) vs. $[EtOK]_o$ exhibit upward curvature. The $k_{obsd}$ value at a fixed $[EtOK]_o$ decreases steeply upon addition of 18-crown-6-ether (18C6) to the reaction mixture up to [18C6]/$[EtOK]_o$ = 1 and then remains nearly constant thereafter. In contrast, $k_{obsd}$ increases sharply upon addition of LiSCN or KSCN. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ has revealed that ion-paired EtOK is more reactive than dissociated $EtO^-$, indicating that $K^+$ ion acts as a Lewis acid catalyst. Hammett plots for the reactions of 1a-e with dissociated $EtO^-$ and ion-paired EtOK result in excellent linear correlation with $\rho$ values of 3.01 and 2.67, respectively. The $k_{EtOK}/k_{EtO^-}$ ratio increases as the substituent X in the benzoyl moiety becomes a stronger electron-donating group. $K^+$ ion has been concluded to catalyze the current reaction by stabilizing the transition state through formation of a 6-membered cyclic complex.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2203-2206
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• 2013

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.179-179
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• 1993

1. PS및 CP의 flux는 전류의 새기 및 donor의 약물농도에 비래하였다. 2. pH의 flux는 pH가 증가할수록 증가하였으나, CP(pKa=9.2)의 flux는 pH=2에서 최대치를 보였다. 이는 약물의 해리 정도와 H$^{＋}$이온의 mobility, 또 피부의 permselectivity의 balance에 의해 결정된 것으로 생각된다. 3. donor cell에 NaCl을 첨가하면 두 약물 공히, 그러나 특히 PS의 flux가 저하되었다. 이는 두 약물의 이온과 $Na^{＋}$의 mobility차이에 기인한다고 생각된다. 4. PS의 경우 taurodeoxycholate(TDC)같은 음이온을 donor cell에 공존시키면 flux가 감소하였다. 이는 PS와 TDC가 전기적으로 중성인 ion-pair complex를 형성함으로써 PS이온의 유효농도가 감소하기 때문으로 생각된다.

• YAKHAK HOEJI
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• v.30 no.2
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• pp.68-72
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• 1986

Effect of sodium taurodeoxycholate (TDC) on the pharmacokinetics of methylene blue (MB) was investigated in the rats of experimental hepatic failure induced by $CCI_4$. Intravenous infusion of TDC increased the distribution volume of central compartment ($Vd_1$) and the total body clearance ($CL_t$) of MB. Increased lipophilicity through ion-pair formation with TDC seemed to be the probable cause of increased $Vd_1$ and $CL_t$.

• ETRI Journal
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• v.31 no.2
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• pp.243-245
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• 2009

A novel ultra-low-power readout circuit for a pH-sensitive ion-sensitive field-effect transistor (ISFET) is proposed. It uses an ISFET/reference FET (REFET) differential pair operating in weak-inversion and a simple current-mode metal-oxide semiconductor FET (MOSFET) translinear circuit. Simulation results verify that the circuit operates with excellent common-mode rejection ability and good linearity for a single pH range from 4 to 10, while only 4 nA is drawn from a single 1 V supply voltage.

• YAKHAK HOEJI
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• v.37 no.1
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• pp.30-35
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• 1993

HPLC/fluorescence detection method for the analysis of pancuronium bromide in biological fluids was developed. The method depends on the formation of insoluble red complex between pancuronium bromide and rose bengal in aqueous layer. This complex is quantitatively extracted from aqueous layer into chloroform layer. The complex is stable for 1 day in chloroform layer at room temperature. It was possible to analyze pancuronium bromide in the range of 0.05~0.5 $\mu\textrm{g}$/ml without the effect of co-prescribed drugs.

• Journal of the Korean Society of Visualization
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• v.9 no.4
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• pp.22-27
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• 2011

In this study, we present methods of coupling a commercial code, ANSYS CFX, and the user Fortran codes for solving an unsteady electro-osmotic flow around a pair of electrodes, receiving DC, attached to the top and the bottom walls of a two-dimensional cavity. We developed a module of Fortran programs for solving the ion-transport equations as well as the Poisson equations for the potential to be used in coupling with the CFX. We present how the developed codes are applied to solving the transient DC electro-osmotic flow problem within a simple cavity. We also address various problems encountered during the development process and explain why such problems are raised.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.303-305
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• 1996

The evolution of solar magnetic arcades is investigated with the use of MHD simulations imposing resistivity on sheared magnetic fields. It is found that there is a critical amount of shear, over which magnetic reconnection can take place ill an arcade-like field geometry to create a magnetic island. The process leading to reconnect ion cannot. be solely attributed to a tearing instability, but rather to a reactive evolution of the magnetic arcade under resistivity. The natures of the arcade reconnection are governed by the spatial pattern of resistivity. A fast reconnection with a small shock angle can only be achieved when the diffusion region is localized. In this case. a highly collimated reconnect ion outflow can tear the plasmoid into a pair, and most of principal features in solar eruptive processes are reproduced.