On the lack of evidence for contact contributions to lanthanide-induced N.M.R. shifts (L.I.S.'s) in aromatic aldehydes: a rigorous error analysis and the isolation of diamagnetic (complexation) shifts.

The adoption of a rigorous error analysis of L.I. S.'s allows the non-pseudo-contact components of the Yb(fod)₃ induced shifts in benzaldehyde and thiophen-2-aldehyde to be isolated. They are largest at the corbonyl carbon and at the ortho and para carbons and appear to be entirely due to complexation (diamagnetic) shifts. Estimation of these with La (fod)₃ allows a precise analysis of the ¹H and ¹³CL.I.S.'s of these aldehydes $\text{without the need to invoke any contact shifts}$.     

Surface and interfacial waves of arbitrary form in isotropic elastic media

A method due to Friedlander of accommodating disturbances of arbitrary form into the theory of surface waves in a semi-infinite isotropic elastic body is extended and shown to yield a simple closed form solution for the displacement field. An analogous treatment of interfacial waves of arbitrary form at a plane contact discontinuity separating different isotropic elastic materials is also given.

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Résumé On développe une méthode, conçue par Friedlander, qui fait entrer les perturbations de forme arbitraire dans la théorie des ondes de surface dans un corps élastique isotropique semi-infini, et on montre qu'elle permet d'obtenir une solution simple et exacte pour le champ de déplacement. Les ondes de forme arbitraire qui existent dans le plan à la frontière de materiaux élastiques isotropiques differents sont traitées de façon analogue.

     

Adsorption of carbon dioxide on graphene oxide supported layered double oxides

Adsorption of CO₂ on layered double oxides supported on graphene oxide has been studied under dry and wet conditions. In the first exposure to the adsorptive gas, the isotherms obtained for supported and unsupported materials are shown to fit to the Freundlich model indicating the existence of heterogeneous adsorption sites. After multiple temperature-swing cycles, the adsorption capacity decreased and the data is better described by the Langmuir model. The presence of graphene oxide is shown to reduce the loss of adsorption capacity, and helps to maintain the heterogeneity of the basic sites on the adsorbents. The use of wet gas mixtures was found to have a positive effect on the CO₂ adsorption capacity of the graphene oxide hybrids. The presence of residual sodium on the materials resulted in a Freundlich isotherm with increased adsorption capacity.     

Structure in rare earth doped β″-alumina

Abstract

Preliminary results of a combined EXAFS and computer simulation study of rare-earth doped β″-alumina are presented.     

Small,but Perfectly Formed: The Microstructure of Nanocrystalline Oxides

There is considerable interest in nanocrystalline materials due to their unusual properties that offer the possibility of exciting technological applications. This paper concentrates on the microstructure of nanocrystalline binary oxides as revealed by X-ray absorption studies. It will be shown that these experiments yield a picture of the materials in which, even when the particles are only a few nanometres in size, the crystallites are highly ordered and the interfaces are similar to grain boundaries in normal bulk solids. This is in conflict with earlier ideas where it was often assumed the surfaces of nanocrystals and the interfaces between them were very disordered.     

Applications of an energy-momentum tensor in non-linear elastostatics

For equilibrium states of elastic materials some general formulae of conservation type have been established in recent papers by Knowles and Sternberg and by Green. It is shown that these results arise naturally from the application of standard integral identities to an energy-momentum tensor first introduced into elastostatics by Eshelby. A duality is exhibited between the energy-momentum tensor and the Cauchy stress which leads directly to inverse deformation relations for elastic solids due originally to Shield.