The discovery in 1954 by Dornberger-Schiff, Liebau and Thilo of the dreierkette (chain repeating at intervals of three tetrahedra), and Liebau's recognition of its significance for the structures of calcium silicates, laid a basis for understanding the most important of the local structures in the nearly amorphous gel which is the principal hydration product of Portland cement. They appear to be related to the structures of two crystalline hydrated calcium silicates, tobermorite and jennite. Knowledge and hypotheses concerning these structures and that of the gel are discussed.
Hydroxamic acids are promising complexant based alternatives to the reductant (U4+ or Fe2+) based selective stripping of Np (and Pu) from a uranium loaded 30% TBP/OK solvent during the reprocessing of irradiated nuclear fuels. Acetohydroxamic acid (AHA) has the benefits of being both a reductant and complexant that efficiently strips Np (and Pu) from solvent phase without adding salt wastes to actinide separation processes. To model these processes, an understanding of Np-hydroxamate chemistry in aqueous and organic solvent is necessary. Three aspects of this system are discussed.