Transmission of Activation in Passive Metals as a Model of the Protoplasmic or Nervous Type of Transmission

Lillie, Ralph S.

doi:10.1126/science.48.1229.51

Cited by 46 publications

(16 citation statements)

References 4 publications

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“…16,17 Since that time, several other oscillatory phenomena have been discovered in the passivation of metals, 1~-2~ in the anodic oxidation of organic compounds, 21-24 and also in the oxidation of hydrogen, 2~' 26 and mathematical treatments have been proposed to explain the observations. 27-~5…”

Section: Electropolymerizationmentioning

confidence: 98%

A New Oscillatory Electrochemical Phenomenon Observed in the Electropolymerization of Pyrrole in MeCN + N ( Bu ) 4 PF 6 on an Iron Electrode Studied by the Ring‐Disk‐Electrode Technique

Petitjean

Aeiyach

Ferreira

et al. 1995

J. Electrochem. Soc.

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A regular oscillatory behavior was observed during the electropolymerization of pyrrole on an iron electrode in aqueous acetonitrile containing tetrabutylammonium hexafluorophosphate. The periodicity, the amplitude, and the shape of the oscillations depend on the concentrations of the electrolyte species. In order to elucidate the mechanism of this oscillatory phenomenon, the ring-disk-electrode technique was used. A mechanism involving a catalytic oxidation of pyrrole by Fe 3 § ions produced during iron oxidation is proposed and discussed. Electropolymerizationconstitutes a well-recognized method for obtaining thin organic coatings adherent to metallic substrates. Previously restricted to the formation of dielectric layers, the advent of conducting polymers at the end of the 1970s has considerably increased its field of application, since polymer films with controllable thickness and good conducting properties can now be obtained easily.However, it must be emphasized that most of the recent electrochemical work devoted to conducting polymers has been carried out with inert metal or semiconductor electrodes, 1 excluding a priori the possibility of using such polymers as anticorrosion coatings for common metals. A few studies on electropolymerization of conducting polymers on oxidizable metals such as iron, aluminum, and titanium have recently been reported. 2-7 Among the various conducting polymers, polypyrrole (PPy) is the most flexible candidate for this purpose, since its electropolymerizatien can be carried out under various conditions, in particular, with nonaqueous 8-I~ and aqueous ~-I~ electrolytes.However, the deposition of polypyrrole on common metals requires special conditions. The solvent and the supporting electrolyte must be carefully chosen to avoid anodic dissolution of the substrate and allow the formation of a polymer film. Beck et al. discovered that under specific conditions, good adherent polypyrrole layers could be formed on iron when nitrate or oxalic acid was present in the aqueous electrolytic solution. 4'5 The acidic character of the solvent, according to the Lewis definition, was also found to be important. With neutral or basic solvents such as propylene carbonate, tetrahydrofuran, or methanol, in the presence of quaternary ammonium salts, pure polypyrrole films can be obtained, whereas in more acidic solvents, such as acetonitrile (MeCN), composite films, consisting of a mixture of PPy and ferric oxides, are formed. 6In this latter case, the phenomenon is particularly complex, since the polymerization of pyrrele and the oxidation of iron occur simultaneously. Moreover the process can be considered as catalytic, because the Fe 3+ ions generated also contribute to the polymerization of pyrrole.7 Nevertheless, by using standard conditions (0.3M pyrrole in anhydrous acetenitrile + 0.1M tetrabutylammonium hexafluorophosphate), the formation of PPy films mixed with iron Present address: LACOR-DEMAT/UFRGS, Porto Alegre, Brazil.136 compounds was clearly demonstrated, and the cyclic voltammogr...

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Section: Electropolymerizationmentioning

confidence: 98%

A New Oscillatory Electrochemical Phenomenon Observed in the Electropolymerization of Pyrrole in MeCN + N ( Bu ) 4 PF 6 on an Iron Electrode Studied by the Ring‐Disk‐Electrode Technique

Petitjean

Aeiyach

Ferreira

et al. 1995

J. Electrochem. Soc.

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“…The most famous example is the electrooxidation of metals, above all, that of iron, which has been investigated as a chemical model for nerve impulse propagation at the beginning of the 20th century 9, 10. Deposition of metals is also often connected with oscillations of the reaction rate.…”

Section: Introductionmentioning

confidence: 99%

Fronts, Waves, and Stationary Patterns in Electrochemical Systems

Krischer

Mazouz

Grauel

2001

Angew. Chem. Int. Ed.

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Oscillatory behavior has been observed for almost all electrochemical reactions in a certain, although sometimes small, range of external parameters. Only in the past ten years has it been possible, however, to find a common explanation for the occurrence of these temporal self‐organization phenomena of chemically completely different electrochemical reactions. The breakthrough was achieved because new methods and concepts, which had been developed in nonlinear dynamics to describe the spontaneous formation of order in various disciplines, could be applied. This development in turn was only possible because the underlying laws are universal at a certain abstract level. Oscillations are only one possible manifestation of nonlinear behavior. Examples of other features that are often closely associated with temporal instabilities are spatial structures and waves. Initiated by the theoretical progress and the development of new experimental techniques, spatial pattern formation in electrochemical systems has been targeted for investigations in the past few years. Based on these investigations, it can be predicted under which conditions temporal or spatial pattern formation can be expected. Furthermore, the possibility of predicting the occurrence of instabilities indicates that it might be feasible to exploit nonlinear effects to increase, for example, the yield of electrocatalytic reactions. Here we discuss physicochemical mechanisms that lead to pattern formation in electrochemical systems. At the same time, we stress the generic principles that are responsible for self‐structuring processes in many chemical and biological systems.

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“…An erster Stelle ist sicherlich die Elektrooxidation von Metallen, allen voran Eisen, zu nennen, die bereits zu Beginn des 20. Jahrhunderts als chemisches Modell für die Nervenreizleitung untersucht wurde 9, 10. Aber auch die Abscheidung von Metallen ist häufig mit Oszillationen der Reaktionsgeschwindigkeit verbunden.…”

Section: Introductionunclassified

Fronten, Wellen und stationäre Muster in elektrochemischen Systemen

2001

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Oszillatorisches Verhalten ist bei nahezu allen elektrochemischen Reaktionen in einem bestimmten, wenn auch in manchen Fällen kleinen Bereich der externen Parameter beobachtet worden. Es ist jedoch erst während der letzten zehn Jahre gelungen, eine einheitliche Erklärung für das Auftreten dieser zeitlichen Selbstorganisationsphänomene bei den chemisch völlig unterschiedlichen elektrochemischen Reaktionen zu geben. Dieser Durchbruch gelang durch die Anwendung von Methoden und Konzepten, die in der nichtlinearen Dynamik entwickelt wurden, um die spontane Bildung von Ordnung in unterschiedlichen Disziplinen zu beschreiben. Dies ist wiederum nur möglich, weil auf einem gewissen Abstraktionsniveau diese Gesetzmäßigkeiten universell sind. Oszillationen sind nur eine mögliche Manifestation nichtlinearen Verhaltens. Beispiele anderer Erscheinungsformen, die häufig mit zeitlichen Instabilitäten eng verbunden sind, sind räumliche Strukturen und Wellen. Ausgelöst durch den theoretischen Fortschritt sowie die Entwicklung neuer experimenteller Methoden wurden während der letzten Jahre gezielte Untersuchungen zur räumlichen Musterbildung in elektrochemischen Systemen durchgeführt, die inzwischen in vielen Fällen eine Vorhersage erlauben, unter welchen Bedingungen eine räumliche oder zeitliche Strukturbildung zu erwarten ist. Dies eröffnet Perspektiven, nichtlineare Effekte zu nutzen, etwa zur Ausbeutesteigerung bei elektrokatalytischen Reaktionen. In diesem Aufsatz werden die physikalisch‐chemischen Mechanismen diskutiert, die zur Musterbildung in elektrochemischen Systemen führen, gleichzeitig werden die übergeordneten allgemeinen Prinzipien betont, die auch für Selbststrukturierungsprozesse in vielen chemischen und biologischen Systemen verantwortlich sind.

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Transmission of Activation in Passive Metals as a Model of the Protoplasmic or Nervous Type of Transmission

Cited by 46 publications

References 4 publications

A New Oscillatory Electrochemical Phenomenon Observed in the Electropolymerization of Pyrrole in MeCN + N ( Bu ) 4 PF 6 on an Iron Electrode Studied by the Ring‐Disk‐Electrode Technique

A New Oscillatory Electrochemical Phenomenon Observed in the Electropolymerization of Pyrrole in MeCN + N ( Bu ) 4 PF 6 on an Iron Electrode Studied by the Ring‐Disk‐Electrode Technique

Fronts, Waves, and Stationary Patterns in Electrochemical Systems

Fronten, Wellen und stationäre Muster in elektrochemischen Systemen

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