Actinides, molecular activation

The complete hydrogenation of carbon dioxide yields methane (and higlter hydrocarbons). Supported nickel catalysts were studied in detail [141 149] and ruthenium catalysts coated on membranes, molecular sieves or aluminum oxides are also very active in CO methanation (ISO I5S]. Intermeiallic compounds like FeTi, or rare earth and actinide intermeiallics,also catalyze the reduction of CO to at, [156 157]. 

Microbes can control the local geochemical environment of actinides and alfect their solubility and transport. Francis et al. (1991) report that oxidation is the predominant mechanism of dissolution of UO2 from uranium ores. The dominant oxidant is not molecular oxygen but Fe(III) produced by oxidation of Fe(II) in pyrite in the ore by the bacteria Thiobacillus ferroxidans. The Fe(III) oxidizes the UO2 to UOl. The rate of bacterial catalysis is a function of a number of environmental parameters including temperature, pH, TDS, fo2, and other factors important to microbial ecology. The oxidation rate of pyrite may be increased by five to six orders of magnitude due to the catalytic activity of microbes such as Thiobacillus ferroxidans (Abdelouas et al., 1999). 

This volume of the Handbook on the Physics and Chemistry of Rare Earths adds five new chapters to the science of rare earths, compiled by researchers renowned in their respective fields. Volume 34 opens with an overview of ternary intermetallic systems containing rare earths, transition metals and indium (Chapter 218) followed by an assessment of up-to-date understanding of the interplay between order, magnetism and superconductivity of intermetallic compounds formed by rare earth and actinide metals (Chapter 219). Switching from metals to complex compounds of rare earths, Chapter 220 is dedicated to molecular stmctural studies using circularly polarized luminescence spectroscopy of lanthanide systems, while Chapter 221 examines rare-earth metal-organic frameworks, also known as coordination polymers, which are expected to have many practical applications in the future. A review discussing remarkable catalytic activity of rare earths in site-selective hydrolysis of deoxyribonucleic acid (DNA) and ribonucleic acid, or RNA (Chapter 222) completes this book. 

ESI has also increased the, until recently limited, investigations of the interactions of rare earth cations with biologically relevant molecules, for example, amino acids (AAs), peptides, and other biomolecules, by ion chemistry methods. These elements are not as important as many others in biological processes, but both the toxicity, through interference with the activity of Ca, and the potential therapeutic uses of these cations are attracting more attention. Curiously, the biocoordination behavior of uranyl and other actinide cations, which could reveal specific molecular interactions involved in transport and chemical toxicity, is relatively tmexplored, including via MS/gas-phase approaches. 

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