Oscillations of the enol form of 2,4-pentanedione during Belousov-Zhabotinskii reaction

1983 ◽  
Vol 48 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Ivan Tkáč ◽  
Ľudovít Treindl
Keyword(s):  
Phase Shift ◽  
Intermediate Product ◽  
Time Course ◽  
Enol Form ◽  
Intermediate Complex ◽  
Redox Catalyst ◽  
Oscillation Reaction ◽  
Belousov Zhabotinskii Reaction

In the Belousov-Zhabotinskii oscillation reaction with 2,4-pentanedione and Mn2+ /Mn3+ redox catalyst, also the enol form of the substrate has an oscillating concentration. The decrease of the concentration of the enol form is due to its reaction with bromine and Mn3+ ions; its increase corresponds to the reestablishment of the keto-enol equilibrium, when the concentrations of bromine and Mn3+ ions are low. An oscillating time-course was observed also with the concentration of the intermediate product of the reaction, of 2,4-pentanedione with Mn3+ ions, probably an intermediate complex [Mn(III)-enol], which oscilated with a phase shift against Mn3+ ions.

Kinetics of oxidation of α-ketoglutaric acid with Ce(IV) ions in relation to Belousov-Zhabotinskii reaction

1982 ◽  
Vol 47 (11) ◽  
pp. 2831-2837 ◽  
Author(s):  
Ľudovít Treindl ◽  
Vasil Dorovský
Keyword(s):  
Redox Reaction ◽  
Platinum Electrode ◽  
Activation Parameters ◽  
Enol Form ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Redox Catalyst ◽  
Oscillation Reaction ◽  
Belousov Zhabotinskii Reaction ◽  
Kinetics Of

Oxidation of α-ketoglutaric acid with Ce(IV) ions in a solution of sulphuric acid is a reaction of the first order with respect to both Ce(IV) ions and substrate, is acid catalysed, and its rate is proportional to the reciprocal square of the equilibrium HSO4- concentration. From the temperature dependence of the rate constant in 1.5M-H2SO4, the activation parameters were determined as ΔH##f = 57 kJ/mol and ΔS##f = -45 J mol-1 K-1. The redox reaction proper consists apparently of two steps: in the first one, the enol form of α-ketoglutaric acid reacts with Ce(IV) ions with the formation of the corresponding radical; in the second one, the latter is oxidized further with Ce(IV) to give malonic and succinic acids. Conditions are indicated under which α-ketoglutaric acid serves as substrate for the Belousov-Zhabotinskii oscillation reaction in the presence of Ce(IV)-Ce(III) redox catalyst. Oscillations of Ce(IV) and Br2 concentrations, shifted in phase, can be recorded polarographically with a rotating platinum electrode.

Belousov–Zhabotinskii type oscillation reaction with glycerol and kinetics of reactions between the system components

1987 ◽  
Vol 52 (10) ◽  
pp. 2375-2382 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Peter Ševčík
Keyword(s):  
Oscillation System ◽  
Chemical Oscillations ◽  
Oscillation Reaction ◽  
Reaction Solution ◽  
System Components ◽  
Probable Source ◽  
Belousov Zhabotinskii Reaction ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Type Oscillation

Glycerol causes chemical oscillations in Belousov-Zhabotinskii reaction in a closed system as well as in a reaction solution bubbled with nitrogen. Since the oxidation of glycerol with bromate ions does not proceed autocatalytically and bromine in the oxidation state 0 or +1 in the absence of light does not react with glycerol, hydrolysis of bromine is the probable source of bromide ions in the studied oscillation system.

Belousov-Zhabotinskii oscillation reaction with glyceraldehyde

1990 ◽  
Vol 55 (7) ◽  
pp. 1673-1677 ◽  
Author(s):  
Milan Melicherčík ◽  
Łudovít Treindl
Keyword(s):  
Organic Radicals ◽  
Analogous Reaction ◽  
Selective Electrode ◽  
Oscillation System ◽  
Pt Electrode ◽  
Redox Catalyst ◽  
Oscillation Reaction ◽  
Bromide Ion ◽  
First Time ◽  
Narrow Concentration Range

An oscillation system of Belousov-Zhabotinskii type with aldehyde as substrate is described for the first time. Oscillations of the concentration of Mn(III) ions can be followed spectrophotometrically or potentiometrically with a Pt electrode in a relatively narrow concentration range of the substrate. In contrast to the analogous reaction with malonic acid, no oscillations of the concentration of Br- ions were detected by a bromide ion selective electrode. This together with the fact that the concentration of Mn(III) ions oscillates even at relatively high bromine concentrations suggests that oscillations of the concentration of the redox catalyst Mn(II)/Mn(III) are probably controlled by organic radicals rather than by Br- ions.

Effect of Pressure Decrease on the Belousov-Zhabotinskii Oscillation Reaction

1993 ◽  
Vol 58 (6) ◽  
pp. 1309-1314 ◽  
Author(s):  
Petr Ševčík ◽  
Lenka Kolínková
Keyword(s):  
Anaerobic Conditions ◽  
Effect Of Pressure ◽  
Oscillation Reaction ◽  
Batch System ◽  
Pressure Decrease ◽  
The Difference ◽  
Belousov Zhabotinskii Reaction ◽  
Oscillatory Cycle

The decrease of pressure from 101.3 kPa to 5.25 kPa has an effect on the parameters of Belousov-Zhabotinskii reaction in batch system in the atmosphere of N2, O2 and CO2. Under the anaerobic conditions, the difference in the form of the reduced phase of oscillatory cycle persists even at vigorous stirring. The role of nucleation, supersaturation, atmosphere, and rate of stirring in these effects is discussed.

Influence of oxygen on Belousov-Zhabotinskii reaction

1980 ◽  
Vol 45 (4) ◽  
pp. 1168-1172 ◽  
Author(s):  
Ľudovít Treindl ◽  
Peter Fabian
Keyword(s):  
Citric Acid ◽  
Induction Period ◽  
Malonic Acid ◽  
Rate Constants ◽  
Activation Parameters ◽  
Oscillation Period ◽  
Redox Catalyst ◽  
Basic Parameters ◽  
Effect Of Oxygen ◽  
Belousov Zhabotinskii Reaction

This work deals with the effect of oxygen on basic parameters of the Belousov-Zhabotinskii reaction in the presence of Ce4+/Ce3+ redox catalyst and malonic acid, citric acid, or 2,4-pentanedione as substrates. Oxygen lowers the duration of the induction period and the first oscillation period as well as the corresponding activation parameters. Oxygen lowers also rate constants and activation parameters for oxidation of malonic and citric acids with Ce4+ ions. It is concluded that the effect of oxygen on the Belousov-Zhabotinskii reaction consists mainly in its catalytic influence on the oxidation of the substrate with Ce4+ ions.

Belousov-Zhabotinskii reaction with ethyl ester of 3-oxobutanoic acid

1983 ◽  
Vol 48 (11) ◽  
pp. 3229-3237 ◽  
Author(s):  
Ľudovít Treindl ◽  
Arpád Nagy
Keyword(s):  
Carbon Dioxide ◽  
Ethyl Ester ◽  
Platinum Electrode ◽  
Reaction System ◽  
Bromo Derivative ◽  
Oscillation Reaction ◽  
Oxobutanoic Acid ◽  
Belousov Zhabotinskii Reaction

The modified Belousov-Zhabotinskii oscillation reaction with ethyl ester of 3-oxobutanoic acid is remarkable in that it does not yield carbon dioxide and the reaction system is closed and homogeneous until an emulsion of a bromo derivative of the substrate appears. As long as the system is homogeneous, it oscillates even in the motionless state and its oscillation behaviour in the absence of oxygen is independent of the intensity of stirring. The results obtained by polarography with a rotating platinum electrode are in agreement with those obtained by spectrophotometry.

Ultrastructural Changes of the Symbiotic Chlorella-Like Alga Isolated from Hydra Viridis

1982 ◽  
Vol 40 ◽  
pp. 320-321
Author(s):  
K.W. Lee ◽  
R.H. Meints ◽  
D. Kuczmarski ◽  
J.L. Van Etten
Keyword(s):  
Time Course ◽  
Reciprocal Cross ◽  
Ultrastructural Level ◽  
Ultrastructural Changes ◽  
Symbiotic Relationship ◽  
Cell Recognition ◽  
Green Hydra ◽  
Different Strains ◽  
Hydra Viridis

The physiological, biochemical, and ultrastructural aspects of the symbiotic relationship between the Chlorella-like algae and the hydra have been intensively investigated. Reciprocal cross-transfer of the Chlorellalike algae between different strains of green hydra provide a system for the study of cell recognition. However, our attempts to culture the algae free of the host hydra of the Florida strain, Hydra viridis, have been consistently unsuccessful. We were, therefore, prompted to examine the isolated algae at the ultrastructural level on a time course.

Destruction of Actin Filaments by Osmium Tetroxide

1977 ◽  
Vol 35 ◽  
pp. 466-467
Author(s):  
P. Maupin-Szamier ◽  
T. D. Pollard
Keyword(s):  
Actin Filaments ◽  
Time Course ◽  
Osmium Tetroxide ◽  
Rabbit Muscle ◽  
Muscle Actin ◽  
Sodium Phosphate Buffer ◽  
Transmission Electron ◽  
The Difference ◽  
Rates Of Decay ◽  
Short Time

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.

Object Wave Determination by Single-Sideband Methods

1973 ◽  
Vol 31 ◽  
pp. 266-267
Author(s):  
Kenneth H. Downing ◽  
Benjamin M. Siegel
Keyword(s):  
Phase Shift ◽  
Carbon Films ◽  
Object Wave ◽  
Electron Wave ◽  
Phase Object ◽  
Heavy Atoms ◽  
Single Sideband ◽  
Thin Carbon ◽  
Additional Phase Shift ◽  
Additional Phase

Under the “weak phase object” approximation, the component of the electron wave scattered by an object is phase shifted by π/2 with respect to the unscattered component. This phase shift has been confirmed for thin carbon films by many experiments dealing with image contrast and the contrast transfer theory. There is also an additional phase shift which is a function of the atomic number of the scattering atom. This shift is negligible for light atoms such as carbon, but becomes significant for heavy atoms as used for stains for biological specimens. The light elements are imaged as phase objects, while those atoms scattering with a larger phase shift may be imaged as amplitude objects. There is a great deal of interest in determining the complete object wave, i.e., both the phase and amplitude components of the electron wave leaving the object.

A Many-Beam Technique for Enhanced Resolution of Partial Dislocations

1972 ◽  
Vol 30 ◽  
pp. 646-647
Author(s):  
J. M. Oblak ◽  
B. H. Kear
Keyword(s):  
Phase Shift ◽  
Field Method ◽  
Dark Field ◽  
Bright Field ◽  
Field Technique ◽  
Weak Beam ◽  
Partial Dislocations ◽  
Enhanced Resolution ◽  
Nickel Base ◽  
Beam Technique

The “weak-beam” and systematic many-beam techniques are the currently available methods for resolution of closely spaced dislocations or other inhomogeneities imaged through strain contrast. The former is a dark field technique and image intensities are usually very weak. The latter is a bright field technique, but generally use of a high voltage instrument is required. In what follows a bright field method for obtaining enhanced resolution of partial dislocations at 100 KV accelerating potential will be described.A brief discussion of an application will first be given. A study of intermediate temperature creep processes in commercial nickel-base alloys strengthened by the Ll2 Ni3 Al γ precipitate has suggested that partial dislocations such as those labelled 1 and 2 in Fig. 1(a) are in reality composed of two closely spaced a/6 <112> Shockley partials. Stacking fault contrast, when present, tends to obscure resolution of the partials; thus, conditions for resolution must be chosen such that the phase shift at the fault is 0 or a multiple of 2π.

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