The Journal of Biological Physics and Chemistry



Volume 10, Number 4, p.p. 152–157



Pressure and the modern mixture model of water

Philippa  M. Wiggins

Department of Medicine, University of Auckland, New Zealand

If just two strengths of water–water hydrogen bonds coexist in the liquid state, localized small pressure gradients, which have been ignored in aqueous solution chemistry “because liquids are incompressible”, have great explanatory power. If water can move to abolish an osmotic pressure gradient, it does so; when, however, it is prevented from moving, the standing gradient acts such that positive pressure induces high density water (HDW) and negative pressure induces low density water (LDW). At a surface HDW and LDW clusters are stabilized so that their properties can be measured. Standing pressure gradients are found at surfaces of solutes, at solid surfaces, at fixed charges on surfaces, at the mouths of pores less than 2 nm in diameter, and in clefts between protein domains: in fact, wherever there is interesting chemistry.


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