There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

An environmental evaluation of geopolymer based concrete production: reviewing current research trends

Correction for ‘Review of electrical energy storage technologies, materials and systems: challenges and prospects for large-scale grid storage’ by Turgut M. Gur, Energy Environ. Sci., 2018, DOI: 10.1039/c8ee01419a.

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Correction: Review of electrical energy storage technologies, materials and systems: challenges and prospects for large-scale grid storage

The author details the reactions of various concretes on steel reinforcement. Although portland cements, slag cements and high alumina cements are all hydraulic binders, each possess special properties which are examined. The discussion of causes and methods of preventing the corrosion of steel reinforcement covers such aspects as galvanised steel reinforcement, effects of concrete composition, corrosion of steel reinforcments in concrete and prestressed reinforcement. It is concluded that the most significant influences on the corrosion of prestressing wire in concrete are: the presence of chloride; the presence of nitrates; the composition of the concrete; the degree of carbonation of the concrete; concrete compaction and, chlorides and sulphates should be used as far as possible when steel is embedded. (TRRL)

Corrosion of steel by concrete

The perovskite (La0.75Sr0.25)Cr0.5Mn0.5O3 (LSCM) is shown to be an effective, redox-stable electrode that can be used for both cathode and anode SOFC operation, to provide a symmetrical fuel cell system with good performance characteristics.

A symmetrical solid oxide fuel cell demonstrating redox stable perovskite electrodes

The best way to reduce the degradation of metallic cultural heritage is through preventive conservation measures but, in many cases, it is not possible to obtain adequate environmental conditions, and it is necessary to apply coatings to the artefacts in order to protect them against corrosion. There is a continuous search in the metal conservation community for new and improved coatings that provide a better protection to the objects whilst respecting the special requirements of the conservation–restoration ethics. Whilst electrochemical techniques have a long tradition in conservation–restoration treatments for metallic cultural heritage, the evaluation of protective coatings using electrochemical impedance spectroscopy (EIS) has only been used very recently. EIS is a very well-established method to investigate metal coatings for general purposes and has many advantages that make it especially suitable for testing coatings for metallic works of art. This paper makes a review of the use of EIS for testing coatings for metallic cultural heritage from the first publications in the mid-1990s to the last papers. The experimental setup used, the types of coatings and metals investigated and the interpretation of the results are reviewed and compared with the use of EIS for testing general purpose anti-corrosive coatings.

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David M. Bastidas

Papers

A symmetrical solid oxide fuel cell demonstrating redox stable perovskite electrodes

Use of EIS for the evaluation of the protective properties of coatings for metallic cultural heritage: a review

A study on the passive state stability of steel embedded in activated fly ash mortars

Electrochemical study on the corrosion behaviour of a new low-nickel stainless steel in carbonated alkaline solution in the presence of chlorides

Steel corrosion behaviour in carbonated alkali-activated slag concrete