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The surface behavior of the natural ruby stones before and after heat treatment with metal oxide additives like: zinc oxide (ZnO) and lead oxide (PbO) have been studied. The surface appearance of the ruby stones processed with the metal oxides changed whereas the bulk densities of the stones remained within the range of 3.9–4.0 g/cm 3 . The cracks healing and pores filling by the metal oxides on the surface of the ruby have been examined using scanning electron microscopy. The chemical compositions based on the XPS survey scans are in good agreement with the expected composition. The phase and crystallinity of the ruby stones original and heat-treated were obtained from their X-ray diffraction patterns. The change in peak separation between R 1 and R 2 – peaks in photoluminescence spectra and the contrary binding energy shift of the Al 2p peaks in the X-ray photoelectron spectra have been explicated. Moreover, in this work we describe the change in surface chemical and physical characteristics of the ruby stone before and after heat treatment. [ABSTRACT FROM AUTHOR]

This study illustrates a density functional theory (DFT) based approach to design the amine collectors with regards to their interaction with the quartz surface. Mechanism of interaction of primary aliphatic amines and their ether and ester derivatives with the quartz surface has been established. Hydrogen bond geometries and adsorption energies as calculated using DFT reveal that ester amines are stronger surfactants compared to the ether amines and primary alkyl amines. Simulation studies carried out for the different amines with number of carbon atoms varying from 10 to 18 suggest that increasing the number of carbon atoms in the alkyl chain enhances the interaction, but not beyond C 14 for primary amines and C 16 for its ether and ester derivatives. Presence of both ether and ester group in the alkyl chain facilitates its interaction strength. Adsorption strength of C 12 amine containing both ether and ester amine is almost equivalent to that of C 16 ester amine. [ABSTRACT FROM AUTHOR]