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Complex permittivity of aqueous solutions of poly(ethy1ene glycol) (PEG), polyvinylpyrrolidone (PVP), Ficoll, dextran and of the phases of aqueous dextran-PEG, dextran-PVP, and dextran-Ficoll biphasic systems of varied polymer concentrations have been measured at four frequencies in the range 1&24 GHz at 25 "C by an interferometric transmission method. It is found that the static dielectric constant of water is enhanced in all the polymer solutions directly with the polymer concentration. The polymers examined slow down the reorientational motion of water molecules and the polymer

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SUMMARY The application of automatic image analysis image techniques in the SEM to massive samples with complex morphology requires a careful choice of the imaging mode and detector geometry used. Thus the quantitative analysis of conjugated surfaces requires summary images, derived from backscattered, secondary, transmitted electron and cathodo‐luminescent signals, as well as dedicated processing algorithms. Careful attention must also be paid to the problems of obtaining and matching these various images.

Superconducting Bi-2212 tapes and laminates are fabricated by a combination of dip-coating and partial melt processing. The heat treated tapes have critical current densities (J c ) up to 11 kA cm −2 . We investigate the degradation of critical current (I c ) during bending experiments for both single tapes and tapes with laminate structure. Although degradation of I c is observed in both forms, the characteristics of the degradation differ. It is determined that laminated tapes perform better than single tapes when critical current is measured against bending radius, and laminated tapes tolerate a higher strain for a given reduction in critical current. It is found that increasing the number of Bi-2212 layers increases the total I c of the laminated tape, but degradation of critical current is more pronounced during bending because of the increased total thickness of the laminate structure. It is also found that addition of silver to the Bi-2212 layers reduces critical current degradation during bending for both tapes and laminates.