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Stochastic resonance (SR) is shown in a two-parameter system, a model of the photosensitive Belousov−Zhabotinsky reaction in a flow system. Light flux and a flow rate are control parameters in a newly developed Oregonator-type model, and the oscillatory behavior of the system is the dynamical observable. Modulation of an excitable focal steady-state close to a Hopf bifurcation by a periodic signal in one parameter and noise in the other parameter is found to give rise to SR. The scenario and novel aspects of SR in this system are discussed.

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Antiagglomeration effects of different surfactants on ice slurry formation were examined to improve the efficiency of an ice-water slurry system to be used for cold thermal storage. Among the chemical surfactants tested, a nonionic surfactant, poly(oxyethylene) sorbitan dioleate, was found to show a greater antiagglomeration effect on the slurry than anionic, cationic, or amphoteric surfactants. More interestingly, diacylmannosylerythritol, a glycolipid biosurfactant produced by a yeast strain of Candida antarctica, exhibited a remarkable effect on the slurry, attaining a high ice packing factor (35%) for 8 h at a biosurfactant concentration of 10 mg/L. These nonionic glycolipid surfactants are likely to effectively adsorb on the ice surface in a highly regulated manner to suppress the agglomeration or growth of the ice particles. This is the first report on the utilization of biosurfactant for thermal energy storage, which may significantly expand the commercial applications of the highly environmentally friendly slurry system.

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