New insights into the intercalation chemistry of Al(OH)3

This paper reports a number of recent developments in the intercalation chemistry of Al(OH)(3). From Rietveld refinement and solid-state NMR, it has been possible to develop a structural model for the recently reported [M(II)Al(4)(OH)(12)](NO(3))(2)·yH(2)O family of layered double hydroxides (LDHs). The M(2+) cations occupy half of the octahedral holes in the Al(OH)(3) layers, and it is thought that there is complete ordering of the metal ions while the interlayer nitrate anions are highly disordered. Filling the remainder of the octahedral holes in the layers proved impossible. While the intercalation of Li salts into Al(OH)(3) is facile, it was found that the intercalation of M(II) salts is much more capricious. Only with Co, Ni, Cu, and Zn nitrates and Zn sulfate were phase-pure LDHs produced. In other cases, there is either no reaction or a phase believed to be an LDH forms concomitantly with impurity phases. Reacting Al(OH)(3) with mixtures of M(II) salts can lead to the production of three-metal M(II)-M(II)'-Al LDHs, but it is necessary to control precisely the starting ratios of the two M(II) salts in the reaction gel because Al(OH)(3) displays selective intercalation of M nitrate (Li > Ni > Co ≈ Zn). The three-metal M(II)-M(II)'-Al LDHs exhibit facile ion exchange intercalation, which has been investigated in the first energy dispersive X-ray diffraction study of a chemical reaction system performed on Beamline I12 of the Diamond Light Source.     

An intermediate wavelength, weakly nonlinear theory for the evolution of capillary gravity waves

A new nonlinear evolution equation is derived for surface solitary waves propagating on a liquid-air interface where the wave motion is induced by a harmonic forcing. Instead of the traditional approach involving a base state of the long wave limit, a base state of harmonic waves is assumed for the perturbation analysis. This approach is considered to be more appropriate for channels of length just a few multiples of the depth. The dispersion relation found approaches the classical long wave limit. The weakly nonlinear dispersive waves satisfy a KdV-like nonlinear evolution equation with steeper nonlinearity.     

Scaling of the Platt electrostatic model of diatomic hydrides

The Platt electrostatic model of a diatomic hydride is modified by the introduction of a scale factor which depends on the internuclear distance. This has the theoretical advantage of enabling the molecular virial theorem to be satisfied and the practical advantage, as shown by some examples, of improving the agreement with experiment particularly for the lighter molecules. The calculation of the scale factor requires two more integrals but the equilibrium internuclear distance and the force constant can still be interpreted electrostatically.     

Molecular‐Sieve Honeycomb for Air Separation from Picea abies

The cellular structure of Norway spruce (Picea abies) was transformed via a simple, single‐step carbonization process into a carbon monolith with molecular‐sieve properties. The monolith exhibited a genuine honeycomb structure derived from the original intrinsic H₂O channels of the wood. The micropores formed during carbonization from the walls of the channels were shown to have a high adsorption capacity. The honeycomb monolith was tested for air separation. Micropore diffusion of N₂ and O₂ was found by the frequency‐response (FR) technique to be the rate‐controlling process of mass transport.     

More mutually orthogonal latin squares

Wilson's construction for mutually orthogonal Latin squares is generalized. This generalized construction is used to improve known bounds on the function n_r (the largest order for which there do not exist r MOLS). In particular we find n₇?780, n₈?4738, n₉?5842, n₁₀?7222, n₁₁?7478, n₁₂?9286, n₁₃?9476, n₁₅?10632.