The adverse effects of sea water environment on the fatigue life of woven carbon fiber/vinyl ester composites are established at room temperature in view of long-term survivability of offshore structures. It is observed that the influence of sea water saturation on the fatigue life is more pronounced when the maximum cyclic displacement approaches maximum quasi-static deflection, that is, the reduction in the number of cycles to failure are comparable between dry and sea water saturated samples at lower strain ranges (37% at 0.46% strain), but are drastically different at higher strain ranges (90% at 0.62% strain). Key damage modes that manifest during the fatigue loading is also identified, and a non-linear model is established for predicting low cycle fatigue life of these composites in dry and sea water saturated conditions.

Atomic force microscopy (AFM) is a powerful, multifunctional imaging platform that allows biological samples, from single molecules to living cells, to be visualized and manipulated. Soon after the instrument was invented, it was recognized that in order to maximize the opportunities of AFM imaging in biology, various technological developments would be required to address certain limitations of the method. This has led to the creation of a range of new imaging modes, which continue to push the capabilities of the technique today. Here, we review the basic principles, advantages and limitations of the most common AFM bioimaging modes, including the popular contact and dynamic modes, as well as recently developed modes such as multiparametric, molecular recognition, multifrequency and high-speed imaging. For each of these modes, we discuss recent experiments that highlight their unique capabilities.