An aggregation of well-organized ZnO whiskers epitaxially grown using a chemical-vapor deposition technique is one of the particularly simple and elegant examples of spontaneous pattern formation. In this study, we analyzed the breaking process of the epitaxial whiskers with and without Al doping using the nanoindentation technique. The whisker diameter and the number density of the whiskers were unchanged with increasing amounts of Al doped into the matrix. The relationship between the breaking load and the length of the whiskers follows Euler's equation, suggesting that the whiskers are destroyed through the bucking process. The degree of elastic deformation is higher for samples including 0.4 and 0.8 at.%Al and lower for those including 1.7 and 2.0 at.%Al than that for nondoped ZnO whiskers. This tendency is also found for the change in the critical load of whisker breaking.

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An aqueous cationic surfactant solution, CTAB/NaSal, forms wormlike micelles and shows viscoelastic properties. It also shows shear-induced structure change at shear rates higher than 4 s-1. Full components of the refractive index tensor under step shear flow were measured by using double-beam rheo-optical analyzer in addition of shear stress and first normal stress difference measurement. Each component of the refractive index tensor is proportional to the corresponding component of the stress tensor when shear rate is lower than 6 s-1. However, a stress-optical coefficient, C, suddenly decreases above 4 s-1. At shear rates between 4 to 6 s-1 , the stress-optic rule holds, but micellar structure might change.

We study the phase diagram of the finite temperature (2 + 1) Abelian Higgs model. We observe, for low values of the quartic scalar self-coupling, the existence of three phases separated by two lines. We study, in detail, the nature of the U(l) deconfining phase transition extension line in the limit of low values of the hopping parameter K for each temperature, and verify that in that limit the behaviour of this line is similar to that of the pure U(l) theory. 0954-3899/90/010001+ 13 $03.50 0 1990 IOP Publishing Ltd