Authors:Shmuel Yariv, Isaak Lapides and Mikhail Borisover
quaternary ammonium cations used in that work were tetraethylammonium (TEA) and benzyltrimethylammonium (BTMA), (Schemes 1 , 2 ), and the clay mineral was MONT heated 2 h in air at 150, 360, and 420 °C. Mild heating of sorbents (at 150 °C) resulted in a
Authors:Hajnalka Ábrahám, A. Losonczy, G. Czéh and Gy. Lázár
Hu, P. S., Benishin, C., Fredholm, B. B. (1991) Comparison of the effects of four dendrotoxin peptides, 4-aminopyridine and tetraethylammonium on the electrically evoked [3H]-noradrenaline from rat hippocampus. Eur. J. Pharmacol. 20 , 87
Authors:D. Wyrzykowski, Agnieszka Pattek-Janczyk, T. Maniecki, Katarzyna Zaremba and Z. Warnke
Thermal decomposition of tetraethylammonium tetrachloro-, bromotrichloro-and tribromochloroferrates(III), of general formula
[(C2H5)4N][FeBr4−nCln] (n=1, 3, 4), has been studied using the TG-MS, DTA and DTG techniques. The measurements were carried out in an argon atmosphere
over the temperature range 293–1073 K. Solid products of the thermal decomposition were identified by Mössbauer spectroscopy.
Authors:K. Jerie, A. Baranowski, Gy. Jákli and J. Gliński
The structure of aqueous solutions of tetraethylammonium chloride was investigated using compressibility and density measurements
and positron annihilation methods. The experimental results are different from those obtained earlier for systems where hydrophobic
hydration dominates, although some evidences for formation of cage-like hydrates in liquid phase were observed. The results
are interpreted, among others, in terms of competition among different hydrates of the tetraethylammonium cations, hydration
of chloride anions, and formation of ionic pairs.
Hydrogen isotope effect in the exchange reaction between HCl
anions in tetramethyl- and tetraethylammonium hydrogen dichloride salts and gaseous HCl has been determined over the temperature range of 273–308 K. Unsymmetrical HCl
anions in the tetramethylammonium salt generate deuterium separation factors between 0.87 and 0.93, while those for symmetrical HCl
anion in the tetraethylammonium salt fall in the range of 0.64–0.76. The former are in good agreement with the theoretical values, while the latter are apparently higher than those predicted by theory. These discrepancies are caused mainly by the presence of more complicated species such as H2Cl
Authors:V. Turov, P. Gorbik, V. Ogenko, O. Shulga and A. Chuiko
A study has been made on samples of dispersed vanadium dioxide (VO2) in a matrix of polyethylene glycol (PEG) doped with a quaternary ammonium salt (QAS), namely tetraethylammonium bromide.
It has been established that under the influence of the dopant the heating of a sample up to the temperature of the metal-semiconductor
phase transition (MSPT) results in a phase in homogeneity of the sample. On the basis of the results of this study it is possible
to conclude that small concentrations of QAS in a PEG matrix can exert a strong effect on the electronic structure of dispersed
VO2 particles. This is accompanied by the appearance of phase heterogeneity of VO2 which manifests itself in the fact that - with the onset of MSPT with increasing temperature - one portion of the substance
passes into the metallic state, and the other remains in the semiconductive state.
Increases in extracellular potassium (K
) concentration (up to 20 mM) cause dilation in some blood vessels. This may be particularly important in myocardial ischemia because in this condition K
is released from ischemic cells. In this study, we investigated mechanisms of effect of increased K
concentration on the tone of isolated bovine coronary artery. Bovine coronary arteries were isolated and mounted in organ baths for isometric tension recording. After an equilibration period, arteries were contracted with serotonin (1 μM). When serotonin contraction reached a steady-state, K
concentration of organ baths was increased from physiological levels to 10 mM, 14 mM, 18 mM or 22 mM in four groups of the arteries. After a washout period, this procedure was repeated in presence of ouabain, a blocker of Na
ATPase or a K
channel blocker (tetraethylammonium, 4-aminopyridine, glibenclamide or barium). Increasing K
concentration of the organ baths to 10 mM, 14 mM and 18 mM caused dilation in the arteries. Ouabain abolished the dilation and barium (a blocker of inward rectifier K
channels) inhibited the dilation significantly.According to our results there is K
-induced dilation in bovine coronary artery and it involves activation of both Na
ATPase and inward rectifier K
Authors:András Pataricza, Z Márton, Z Hegedűs, Irén Krassói, A Kun, A Varró and J Gy Papp
Functional role of calcium-activated potassium (KCA) channels on the basal and agonist-elevated arterial tones was investigated in isolated rabbit aorta, porcine and canine coronary arteries as well as in human internal mammary artery. The vascular tones enhanced by contractile agents were increased further by preincubation of these conduit blood vessels with selective (charybdotoxin or iberiotoxin) or non-selective (tetraethylammonium) inhibitors of KCA channels. The basal tone (without an agonist) was increased only in the canine coronary artery. The results indicate a feed-back regulatory role of KCA channels counteracting the vasospasm of conduit arteries.
The kinetics of deuterium and chlorine-36 isotope exchange between hydrogen dichloride ions in tetramethyl- and tetraethyl-ammonium salts and hydrogen chloride has been studied in the temperature range 275–304 K. On the basis of the results obtained the exchange mechanism was proposed emphasizing the role of hydrogen bonding in the exchange process.
Authors:E. Styczeń, W. Jóźwiak, M. Gazda, D. Wyrzykowski and Z. Warnke
Thermal decomposition of compounds consisting of tetrahalogenocuprate(II), [CuBrnCl4−n]2− (n=0–4) anions and a tetraethylammonium cation has been studied using TG-FTIR, TG-MS, DTA and DTG techniques. The measurements
were carried out in an argon and air atmospheres over the temperature range 293-1073 K. The products of the thermal decomposition
were identified by IR and Far Infrared (FIR) spectroscopy as well as X-ray powder diffractometry.