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This article presents a comparison of data obtained from a low-temperature cure of an epoxy/amine system by three independent cure monitoring techniques: ultrasonic wave propagation, dielectric permittivity, and nuclear magnetic resonance. The sizes and thermal histories of the samples studied by the three techniques were controlled for comparability between the methods. The three techniques gave consistent information on the progress of cure and were complementary, in that each was particularly sensitive to different stages of the cure process.

Aims:  This study evaluated the effect of protozoan movement and grazing on the topography of a dual‐bacterial biofilm using both conventional light microscopy and a new ultrasonic technique. Methods and Results:  Coupons of dialysis membrane were incubated in Chalkley’s medium for 3 days at 23°C in the presence of bacteria (Pseudomonas aeruginosa and Klebsiella aerogenes) alone, or in co‐culture with the flagellate Bodo designis, the ciliate Tetrahymena pyriformis or the amoeba Acanthamoeba castellanii. Amoebic presence resulted in a confluent biofilm similar to the bacteria‐only biofilm while the flagellate and ciliate created more diverse biofilm topographies comprising bacterial microcolonies and cavities. Conclusions:  The four distinct biofilm topographies were successfully discerned with ultrasonic imaging and the method yielded information similar to that obtained with conventional light microscopy. Significance and Impact of the Study:  Ultrasonic imaging provides a potential way forward in the development of a portable, nondestructive technique for profiling the topography of biofilms in situ, which might aid in the future management of biofouling.

This paper is concerned with modeling ultrasonic wave propagation in epoxy materials to better understand NDE procedures and to provide reliable input to more complex models of guided wave propagation in layered structures. Different physical models are considered in the context of how well they simulate the (known) linear relationship between bulk wave attenuation coefficients and frequency. The identified models are then extended to simulate wave propagation in materials with mechanical properties, which vary gradually in the spatial dimension. This is achieved using electric circuit transmission line analogs to the viscoelastic mechanical system. Verifying experimental results are included.

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