Zoltán Noszticzius - Academia.edu (original) (raw)

Papers by Zoltán Noszticzius

Chemischer Informationsdienst, Oct 9, 1979

ChemInform Abstract Sowohl bei diskontinuierlicher als auch bei stetiger Ag-Zugabe zur Senkung de... more ChemInform Abstract Sowohl bei diskontinuierlicher als auch bei stetiger Ag-Zugabe zur Senkung der Bf-Konzentration' werden im Verlauf der Titelreaktion Oszillationen des Redoxpotentials beobachtet, während derer sich das Potential der für Bromidionen spezifischen Elektrode stetig bzw. mit einer geringen Amplitude oszillierendändert.

The Journal of Physical Chemistry, Feb 1, 1992

very rapidly at low flow rates. Values corresponding to the three stages of the batch reaction ap... more very rapidly at low flow rates. Values corresponding to the three stages of the batch reaction appear over a very narrow flow rate range as is shown in Figure 7. The simulations are very sensitive in this region, and it may be that the observed noisy oscillations in our and Simoyi'~'~ CSTR experiments result from an extreme sensitivity of the experimental system to environmental perturbation. The effect of mixing3' experimentally and in this model (31) GvBrnvi. L.:

Springer eBooks, 1984

Recently a new reaction scheme the “Explodator” core was proposed by us [1, 2] as a simple model ... more Recently a new reaction scheme the “Explodator” core was proposed by us [1, 2] as a simple model for chemical oscillations. Limit cycle oscillators can be constructed using that explosive core and different limitary reactions.

Periodica Polytechnica Mechanical Engineering, 1977

The Journal of Physical Chemistry, Aug 1, 1990

We have performed experiments on the Belousov-Zhabotinskii reaction perturbed by ultraviolet ligh... more We have performed experiments on the Belousov-Zhabotinskii reaction perturbed by ultraviolet light and by silver ions, and over a range of sulfuric acid concentrations, the reaction shows a large sensitivity to these perturbations. Our results support Forsterling and Noszticzius' theory of malonyl radicals as a second control intermediate. Results of perturbation by both ultraviolet light and silver ions at the same time, however, are not adequately explained by either malonyl radical control or bromide control (or both) and suggest a third control intermediate such as bromomalonyl radicals.

The Journal of Physical Chemistry, 1977

The Journal of Physical Chemistry, Apr 1, 1989

The Journal of Physical Chemistry, 1988

The summation over u in (A17) is taken up to the dissociation limit of H2(X). Case 4. In this cas... more The summation over u in (A17) is taken up to the dissociation limit of H2(X). Case 4. In this case, one considers the process in case 3 except for the additional assumption that no torque works on H2 in the dissociation. With this condition, K is always perpendicular to N and the rotation of H2 originates only from that of the parent molecule. Conservation of energy and that of angular momentum are the same as those in case 3 ((A15) and (A16)). The rate of formation, P(N), is expressed as L: (J.I.K)ED P(N) c z z Cg(J)g'(K)p(E,) where D: {(J,I,K)lI + K + N = J, K I N , hill I (2mHEk The definition of Ek is identical with that in (A rotational distribution of H2, g'(K), is assumed to be the Boltzmann distribution at 300 K. The condition that K I N is treated in the counting of quantum states as follows: If N I K , Le., N-K = 0, the vector sum, M, of N and K is given by IMI2 = lNIZ + (KI2 (A23) The representation in which lMI2, INI2, and lKI2 are simultaneously diagonal being taken, one obtains that M (M + 1) = N(N + 1) + K (K + 1) (A24) Since M , N, and K are all integers, (A24) is not satisfied except by chance. Namely, the geometrical condition that N I K is meaningful only in the classical limit, because the direction of the angular momentum is not observable in quantum mechanics. In the present analysis, M is calculated by solving (A24) with given N a n d K and then this value is replaced by the nearest integer.

Berichte der Bunsengesellschaft für physikalische Chemie, Apr 1, 1980

Four new experimental observations are discussed which are difficult to interpret if we regard th... more Four new experimental observations are discussed which are difficult to interpret if we regard the bromide ion as a control intermediate of the BZ reaction. To explain the experimental facts two new hypothetical models: the bromine controlled (BC) model of the heterogeneous oscillations (substrate oxalic acid) and the Lotka‐Volterra (LV) model of the homogeneous oscillations with mixed substrate (oxalic acid‐aceton) are presented. Some variations of the more realistic LV model are mentioned.

Journal of Physical Chemistry A, Jun 1, 1999

The Ce 4+-malonic/bromomalonic acid reactions play an important role in the oscillatory Belousov-... more The Ce 4+-malonic/bromomalonic acid reactions play an important role in the oscillatory Belousov-Zhabotinsky reaction. In this work CO 2 evolution from these reactions was studied with a sensitive and quantitative method, by converting the CO 2 to methane and measuring it with a flame ionization detector. It was found that the stoichiometries depend on the initial conditions in batch experiments or on the mixing rate of reagents in a semibatch reactor. These findings are explained by two main reaction channels: one for recombination and another for decarboxylation. Decarboxylation itself has two separate routes, one is dominant at low while the other at high Ce 4+ concentrations. In the latter, formation of more than two CO 2 molecules from one malonic/bromomalonic acid molecule was observed. Novel reaction schemes containing carbenes are proposed for these "high Ce 4+ " decarboxylation channels. To check the new mechanism, HPLC measurements are planned as a continuation of the research.

$Research paper thumbnail of Turing patterns visualized by index of refraction variations$

Journal of Chemical Physics, Mar 1, 1992

The Journal of Physical Chemistry, Jul 1, 1987

model,2' A,G" is a function of the ionic charge and radius and of the solvent permittivity. It is... more model,2' A,G" is a function of the ionic charge and radius and of the solvent permittivity. It is therefore not surprising that the three anions, NOT, 03'-, and SO2'-, have Gibbs solvation energies that are rather similar, and the extrapolation to C02*-seems justified. The major source of error in our estimate lies in the uncertainty of the electron affinity. The values of A,Go given above are relative to A,+Go(H+) = 0. Absolute Gibbs hydration energies are 03*- ,-3 18 kJ/mol; NO<,-302 kJ/mol; SOz'- ,-304 kJ/mol; and C02'- ,-310 f 8 kJ/mol based on Rosseinsky'sz2 value for AfGo(H+) corrected for Klots'sZ3 revised A,Go(H+). The reduction potentials calculated above allow a complete oxidation-state diagram of C , compounds containing hydrogen and oxygen to be constructed, Figure 1. It shows that the oneelectron oxidation of formate is energeticaly comparable to the oxidations of methanol and formaldehyde, while oxidation of methane is much more unfavorable. A C-0 or C=O bond appears to make a hydrogen bound to the same carbon atom more susceptible to abstraction as illustrated in the reaction of ethanol with the hydroxyl radical which leads for approximately 90% to the radical CH3CHOH, while only 10% C H 2 C H 2 0 H is formed. The formate radical is not only unstable with respect to formate and carbon dioxide (Ar,,Go =-281 f 44 kJ/2 mol of COz'-), but also to carbon monoxide, water, and carbon dioxide (A,,,Go =-247 rt 44 kJ/2 mol of COz'-). Dimerization to oxalate is also very favorable: Ar,,G" =-258 f 44 kJ/2 mol of C0,'-and appears to be the main pathway for decay of the formate radi~a1.l~

Journal of the Chemical Society, 1976

In tracer diffusion experiments, the linear dependence of the measured intensity with time is use... more In tracer diffusion experiments, the linear dependence of the measured intensity with time is useful as an approximation after a certain induction time. We have shown here that by choosing suitable initial conditions and counting efficiency, the linear plot applies from the commencement of the experiment.A study using non-radioactive methods to determine the concentration of the diffusing substance has also been made. The concept of a measuring functional, which may be linear or non-linear with respect to the concentration, has been used. In such cases after a set time the logarithm of the measured quantity follows a straight line with respect to time, and the first eigenvalue which includes the diffusion coefficient can be obtained from the slope. Harned and Nuttal's conductance method is an example of the use of a non-linear functional to determine the diffusion coefficient.

Reaction Kinetics and Catalysis Letters, Sep 1, 1990

A new theory of the Belousov-Zhabotinsky (BZ) reaction, the Radicalator model, is presented. This... more A new theory of the Belousov-Zhabotinsky (BZ) reaction, the Radicalator model, is presented. This model is based on a negative feedback loop involving a fast reaction between malonyl and bromine dioxide radicals. Experimental evidence for the validity of the model is given for BZ systems in 3 M and 1 M sulfuric acid solution.

Journal of Physical Chemistry A, Oct 14, 2000

The effect of oxygen on the Ce4+−malonic acid reaction was studied in a semibatch reactor. That e... more The effect of oxygen on the Ce4+−malonic acid reaction was studied in a semibatch reactor. That effect is important for the Belousov−Zhabotinsky (BZ) chemical oscillator. The Ce4+ reagent inflow and consequently the rate of the reaction itself was controlled by a peristaltic pump. The reaction products were analyzed by HPLC. With this technique two major oxidation pathways were identified. One is significant at high Ce4+ inflow rates only; the product of this channel is tartronic acid. The other pathway leading to oxalic acid is active at all flow rates but dominant when the feed is slow. A great part of oxalic acid is oxidized further to carbon dioxide and water. A reaction mechanism compatible with these findings is presented. A key step of this mechanism is the fate of the peroxymalonyl radical which is the first intermediate for both channels. It is proposed that at high Ce4+ concentrations a fast reaction of this intermediate with Ce4+ leads to tartronic acid. At low Ce4+ concentrations, however, the...

Journal of the Chemical Society, 1985

A new class of generalized Lotka–Volterra schemes has been investigated. It is shown that such sy... more A new class of generalized Lotka–Volterra schemes has been investigated. It is shown that such systems are conservative. Their first integrals can be used as Liapunov functions to prove the globally stable or explosive behaviour of a wide class of modifications. On modifying the value of an exponent in one rate law, a ‘critical’ Hopf bifurcation occurs and the stable and the explosive regions are separated by a critical value at which conservative oscillations take place. The explosive schemes can be regarded as two-dimensional explodator cores. Limit-cycle oscillators can be constructed using these cores and one or more limiting reactions.