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A full order parameter analysis has been carried out on a peptide plane of gramicidin A in aligned phospholipid bilayers. The most ordered molecular axis was determined to be the helical long axis of the molecule, possessing an order parameter of 0.93 -4-0.03 parallel to the bilayer normal, and an axial symmetry of -0.06 d: 0-04.

Band gap engineering of TiO 2 has attracted many researchers looking to extend its applicability as a functional material. Although TiO 2 has been commercialised in applications that utilise its special properties, its band gap should be modified to improve its performance, especially as an active photo catalyst. Reduction of TiO 2 under a hydrogen atmosphere is a promising method which can increase the visible-light absorption efficiency of TiO 2 and enhance its electrochemical and other properties related to electronic band structure. In this second review paper, the production and influence of O vacancies ( ) and other defects, such as interstitial cations, under vacuum and hydrogen are reviewed for the common phases of TiO 2 . The particular modification TiO 2-x in which O is randomly removed from the crystal structure is considered in detail. Despite early evidence that hydrogen is absorbed into the bulk of TiO 2 , the action of hydrogen has become controversial in recent years, with claims that surface disorder is responsible for the enhanced photoactivity induced by exposure to hydrogen. The many published experimental and density-functional-theory modelling studies are surveyed with the aims of determining what is agreed or contested, and relating defect structure to band structure. It is concluded that further work is needed to clarify the mechanisms of defect production and defect diffusion, as well as the origins of the numerous sample colours observed following treatment in vacuum or hydrogen.

Frothers, a class of surfactants, are widely employed in froth flotation to aid the generation of small bubbles. Their action is commonly explained by their ability to hinder coalescence. There are occasional references suggesting that the frother may also play a role in the initial breakup of the injected air mass. This work investigates the possible effect of the frother on breakup by monitoring air bubbles produced quasi-statically at an underwater capillary. Under this condition, breakup is isolated from coalescence and an impact of frothers on the detached bubble can be ascribed to an impact on breakup. The breakaway process was monitored by an acoustic technique along with high-speed cinematography. The results showed that the presence of frothers did influence the breakaway process and that the acoustic technique was able to detect the impact. It was demonstrated that the acoustic frequency and acoustic damping ratio depend upon the frother type and concentration and that they are associated with a liquid jet, which initially excites the bubble and then decays to form a surface wave. The addition of the frother did not influence the formation of the jet but did increase its decay rate, hence, dampening the surface wave. It is postulated that the action of the frother is related to an effect on the magnitude of surface tension gradients.

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