Modified semi-ion-pair model for the evaluation of activation energies of four-center reactions of hydrogen halides to olefins

1974 ◽  
Vol 78 (10) ◽  
pp. 1035-1040 ◽  
Author(s):  
K. R. Maltman ◽  
E. Tschuikow-Roux ◽  
K. H. Jung
Keyword(s):  
Activation Energies ◽  
Ion Pair ◽  
Hydrogen Halides ◽  
Pair Model

Electronic structure of the ion pair model for Ti:Al2O3

1994 ◽  
Vol 6 (32) ◽  
pp. 6497-6505 ◽  
Author(s):  
F X Zha ◽  
J H Zhang ◽  
S D Xia
Keyword(s):  
Electronic Structure ◽  
Ion Pair ◽  
Pair Model

Dielectric Effect on the Vibrational Frequencies of 1-ethyl-3-methylimidazorium Tetrafluoroborate Ion-Pair Model System Studied by DFT with SCRF Calculation

2005 ◽  
Vol 73 (8) ◽  
pp. 589-592 ◽  
Author(s):  
Tomonori KATO ◽  
Noritoshi NANBU ◽  
Yukio SASAKI ◽  
Takeo OHSAKA ◽  
Fusao KITAMURA
Keyword(s):  
Model System ◽  
Ion Pair ◽  
Vibrational Frequencies ◽  
Pair Model ◽  
Dielectric Effect

Electrochemical Investigation for Cu2+ Oscillatory Phenomena at the Liquid/Liquid Interface with a Specific Adsorption of Ion Pair Model

2012 ◽  
Vol 24 (9) ◽  
pp. 1817-1823 ◽  
Author(s):  
Yijun Zhang ◽  
Caihong Bu ◽  
Yongcheng Wang ◽  
Zhihua Wang ◽  
Xiaoquan Lu ◽  
...  
Keyword(s):  
Ion Pair ◽  
Liquid Interface ◽  
Specific Adsorption ◽  
Electrochemical Investigation ◽  
Pair Model

scholarly journals Intracellular pH-regulating mechanism of the squid axon. Interaction between DNDS and extracellular Na+ and HCO3-.

1989 ◽  
Vol 93 (1) ◽  
pp. 123-150 ◽  
Author(s):  
W F Boron ◽  
R C Knakal
Keyword(s):  
Intracellular Ph ◽  
Kinetic Models ◽  
Ion Pair ◽  
Squid Axon ◽  
Maximal Inhibition ◽  
Extrusion Rate ◽  
Stilbene Derivative ◽  
Pair Model ◽  
Acid Extrusion ◽  
Best Fit

Intracellular pH (pHi) of the squid axon is regulated by a stilbenesensitive transporter that couples the influx of Na+ and HCO3- (or the equivalent) to the efflux of Cl-. According to one model, the extracellular ion pair NaCO3- exchanges for intracellular Cl-. In the present study, the ion-pair model was tested by examining the interaction of the reversible stilbene derivative 4,4'-dinitrostilbene-2,2'-disulfonate (DNDS) with extracellular Na+ and HCO3-. Axons (initial pHi approximately 7.4) were internally dialyzed with a pH 6.5 solution containing 400 mM Cl- but no Na+. After pHi, as measured with a glass microelectrode, had fallen to approximately 6.6, dialysis was halted. In the presence of both external Na+ and HCO3- (pHo = 8.0, 22 degrees C), pHi increased due to the pHi-regulating mechanism. At a fixed [Na+]o of 425 mM and [HCO3-]o of 12 mM, DNDS reversibly reduced the equivalent acid-extrusion rate (JH) calculated from the rate of pHi recovery. The best-fit value for maximal inhibition was 104%, and for the [DNDS]o at half-maximal inhibition, 0.3 mM. At a [Na+]o of 425 mM, the [HCO3-]o dependence of JH was examined at 0, 0.1, and 0.25 mM DNDS. Although Jmax was always approximately 20 pmol cm-2 s-1, Km(HCO3-) was 2.6, 5.7, and 12.7 mM, respectively. Thus, DNDS is competitive with HCO3-. At a [HCO3-]o of 12 mM, the [Na+]o dependence of JH was examined at 0 and 0.1 mM DNDS. Although Jmax was approximately 20 pmol cm-2 s-1 in both cases, Km(Na+) was 71 and 179 mM, respectively. At a [HCO3-]o of 48 mM, Jmax was approximately 20 pmol cm-2 s-1 at [DNDS]o levels of 0, 0.1, and 0.25 mM. However, Km(Na+) was 22, 45, and 90 mM, respectively. Thus, DNDS (an anion) is also competitive with Na+. The results are consistent with simple competition between DNDS and NaCO3-, and place severe restrictions on other kinetic models.

Association of radical anions alkali metal cations. III. Experimental and theoretical study of the associates of nitrobenzene radical anions with Li+, Na+, K+, Cs+ and (n-C4H9)4N+ cations

1980 ◽  
Vol 45 (2) ◽  
pp. 360-368 ◽  
Author(s):  
Stanislav Miertuš ◽  
Ondrej Kyseľ ◽  
Juraj Danciger
Keyword(s):  
Quantum Chemical ◽  
Theoretical Study ◽  
Geometrical Structure ◽  
Uv Spectroscopy ◽  
Ion Pair ◽  
Radical Anions ◽  
Alkali Metal Cations ◽  
Polar Medium ◽  
Pair Model ◽  
Free Ion

The nitrobenzene radical anion prepared by electrolysis was studied by UV spectroscopy. Formation of associates with Li+, Na+, K+, Cs+ and n(C4H9)4N+ cations was examined. It has been found that associates are also formed in a polar medium such as dimethylformamide. The enthalpy of the associated-free ion equilibrium was estimated as being equal to 6+4 kJ/mol-1. The quantum-chemical LHP method (in the π-approximation) was employed to study a simple ion pair model used for calculation of the most stable geometrical structure.

scholarly journals Intracellular pH-regulating mechanism of the squid axon. Relation between the external Na+ and HCO-3 dependences.

1985 ◽  
Vol 85 (3) ◽  
pp. 325-345 ◽  
Author(s):  
W F Boron
Keyword(s):  
Intracellular Ph ◽  
Recovery Rate ◽  
Ion Pair ◽  
Squid Axon ◽  
Extrusion Rate ◽  
Pair Model ◽  
Buffering Power ◽  
Series Of Experiments ◽  
Acid Extrusion ◽  
External Ph

The intracellular pH-regulating mechanism of the squid axon was examined for its dependence on the concentrations of external Na+ and HCO3-, always at an external pH (pHo) of 8.0. Axons having an initial intracellular pH (pHi) of approximately 7.4 were internally dialyzed with a solution of pH 6.5 that contained 400 mM Cl- and no Na+. After pHi had fallen to approximately 6.6, dialysis was halted, thereby returning control of pHi to the axon. With external Na+ and HCO-3 present, intracellular pH (pHi) increased because of the activity of the pHi-regulating system. The acid extrusion rate (i.e., equivalent efflux of H+, JH) is the product of the pHi recovery rate, intracellular buffering power, and the volume-to-surface ratio. The [HCO3-]o dependence of JH was examined at three fixed levels of [Na+]o: 425, 212, and 106 mM. In all three cases, the apparent Jmax was approximately 19 pmol X cm-2 X s-1. However, the apparent Km (HCO3-) was approximately inversely proportional to [Na+]o, rising from 2.6 to 5.4 to 9.7 mM as [Na+]o was lowered from 425 to 212 to 106 mM, respectively. The [Na+]o dependence of JH was similarly examined at three fixed levels of [HCO3-]o: 12, 6, and 3 mM. The Jmax values did not vary significantly from those in the first series of experiments. The apparent Km (Na+), however, was approximately inversely related to [HCO3-]o, rising from 71 to 174 to 261 mM as [HCO3-]o was lowered from 12 to 6 to 3 mM, respectively. These results agree with the predictions of the ion-pair model of acid extrusion, which has external Na+ and CO3= combining to form the ion pair NaCO3-, which then exchanges for internal Cl-. When the JH data are replotted as a function of [NaCO3-]o, data from all six groups of experiments fall along the same Michaelis-Menten curve, with an apparent Km (NaCO3-) of 80 microM. The ordered and random binding of Na+ and CO3= cannot be ruled out as possible models, but are restricted in allowable combinations of rate constants.

scholarly journals Na+ Cl− ion pair association in water-DMSO mixtures: Effect of ion pair model potentials

2016 ◽  
Vol 128 (6) ◽  
pp. 1003-1010 ◽  
Author(s):  
ATANU SARKAR ◽  
ANUPAM CHATTERJEE ◽  
S C TIWARI ◽  
B L TEMBE
Keyword(s):  
Ion Pair ◽  
Model Potentials ◽  
Pair Model
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