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Biomedical subjects

DJ Pine

Publications and source records attributed to DJ Pine.

At least 19 recordsLinked to original sources
PubMed1997

Imaging of intermittency in ripple-wave turbulence

The dynamics of a fluid surface filled with high-amplitude ripples were studied with a technique (diffusing light photography) that resolves the height at all locations instantaneously. Even when nonlinearities are strong enough to generate a (Kolmogorov) cascade from long wavelength (where energy is input) to shorter wavelength, the resulting turbulent state contains large coherent spatial structures. The appearance of these structures in a thermal equilibrium state (with the same average energy) would be highly improbable.

Journal Article↗
PubMed1997

Stability of Nonaqueous Emulsions

We examined the stability of emulsions of oil in several nonaqueous polar liquids using commercially available nonionic surfactants. Stable nonaqueous emulsions were only obtained with formamide and dimethylsulfoxide. Hydrogen bonding, and not polarity, appears to be the important factor determining the emulsifying power of a solvent. Ostwald ripening plays a much more important role in the stability of these nonaqueous emulsions than in the corresponding aqueous systems. This destabilizing process can be prevented, however, by addition to the oil phase of a small amount (1%) of an oil that has a very low solubility in the continuous phase. Furthermore, a larger size of the surfactant molecule protects emulsions against droplet coalescence. Thus, emulsions in formamide and dimethylsulfoxide did not show any breakdown when stabilized with a triblock copolymer of polyoxyethylene-polyoxypropylene-polyoxyethylene. Copyright 1997Academic Press

Journal Article↗