http://hdl.handle.net/1842/3421 2013-05-21T17:38:04Z 2013-05-21T17:38:04Z Loveday, J. S. Nelmes, R. J. http://hdl.handle.net/1842/3987 2010-10-18T12:36:57Z 2008-02-01T00:00:00Z

Title: High-pressure gas hydrates Authors: Loveday, J. S.; Nelmes, R. J. Abstract: It has long been known that crystalline hydrates are formed by many simple gases that do not interact strongly with water, and in most cases the gas molecules or atoms occupy 'cages' formed by a framework of water molecules. The majority of these gas hydrates adopt one of two cubic cage structures and are called clathrate hydrates. Notable exceptions are hydrogen and helium which form 'exotic' hydrates with structures based on ice structures, rather than clathrate hydrates, even at low pressures. Clathrate hydrates have been extensively studied because they occur widely in nature, have important industrial applications, and provide insight into water-guest hydrophobic interactions. Until recently, the expectation-based on calculations-had been that all clathrate hydrates were dissociated into ice and gas by the application of pressures of 1 GPa or so. However, over the past five years, studies have shown that this view is incorrect. Instead, all the systems so far studied undergo structural rearrangement to other, new types of hydrate structure that remain stable to much higher pressures than had been thought possible. In this paper we review work on gas hydrates at pressures above 0.5 GPa, identify common trends in transformations and structures, and note areas of uncertainty where further work is needed.

2008-02-01T00:00:00Z Egelhaaf, Stefan U Baker, M.E. Shaw, N. Fairhurst, David John http://hdl.handle.net/1842/3034 2011-05-25T09:45:39Z 2008-05-01T00:00:00Z

Title: Swelling and shrinking kinetics of a lamellar gel phase Authors: Egelhaaf, Stefan U; Baker, M.E.; Shaw, N.; Fairhurst, David John Abstract: We investigate the swelling and shrinking of L-beta lamellar gel phases composed of surfactant and fatty alcohol after contact with aqueous poly(ethyleneglycol) solutions. The height change Delta h(t) is diffusionlike with a swelling coefficient S: Delta h=S root t. On increasing polymer concentration, we observe sequentially slower swelling, absence of swelling, and finally shrinking of the lamellar phase. This behavior is summarized in a nonequilibrium diagram and the composition dependence of S quantitatively described by a generic model. We find a diffusion coefficient, the only free parameter, consistent with previous measurements.

2008-05-01T00:00:00Z Haw, Mark http://hdl.handle.net/1842/691 2011-02-28T15:14:15Z 2002-06-27T00:00:00Z

Title: Quantum Physics: Altered States Authors: Haw, Mark Abstract: Stand by for a new state of matter — according to some predictions, it could be created in the next few months. In a handful of laboratories around the world, physicists are trying to persuade antisocial atoms to pair up to form a new type of ‘superatom’. If they succeed, their creations will have more than curiosity value.The state — called a fermion condensate — would be perfect for testing theories of quantum mechanics, and could even lead to new ways of computing.

2002-06-27T00:00:00Z