Angus P Wilkinson

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We characterize intercalative complexes as either "high charge" and "low charge". In low charge complexes, stacking interactions appear to dominate stability and structure. The dominance of stacking is evident in structures of daunomycin, nogalamycin, ethidium, and triostin A/echinomycin. By contrast in a DNA complex with the tetracationic metalloporphyrin(More)
Scandium trifluoride maintains a cubic ReO(3) type structure down to at least 10 K, although the pressure at which its cubic to rhombohedral phase transition occurs drops from >0.5 GPa at ∼300 K to 0.1-0.2 GPa at 50 K. At low temperatures it shows strong negative thermal expansion (NTE) (60-110 K, α(l) ≈ -14 ppm K(-1)). On heating, its coefficient of(More)
Synchrotron X-ray powder diffraction data (SPDD) for representative LiMF6 and Li2MF6 salts of the second and third transition series have provided unit-cell parameters and, from Rietveld analysis, M-F interatomic distances. M-F distances have also been obtained from X-ray single-crystal structural analyses of LiOsF6, Li2PtF6, and KRhF6. The LiMF6 all have(More)
Attack of Portland cement by ambient sulfates presents a considerable risk to structures in some environments. In this study, x-ray microtomography, a high resolution variant of medical “CT”, noninvasively mapped the progression of damage in Portland cement resulting from exposure to an aqueous solution of Na2SO4 (sodium ion concentration of 10,000 ppm).(More)
Sulfate attack is potentially one of the most damaging forms of degradation affecting portland cement-based materials. However, despite over six decades of study, considerable uncertainty remains in optimally selecting and proportioning materials for sulfate resistance, and current understanding of the actual mechanisms of degradation in sulfate(More)
Nickel substituted nontronite (~ 2 wt.%) is an important nickel resource in the Western Australian laterite profile. However, the quantitative phase analysis of nontronite has proven to be difficult as this clay mineral is always turbostratically disordered and lacks periodicity in the [00l] direction. Therefore a three dimensional unit cell does not exist(More)