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The steels fracture toughness was measured at two different temperature T= - 60°C and T = -90°C, at v=0.02 mm/min and v=0.5 mm/min. The following steels: CrMoV, 20MnMoNi55, A533B and A508 were tested with three different sizes of CT specimens 50 and 100 and 200. Those steels are weldable, although the authors investigated the fracture behaviour of base material. In order to satisfy statistical analyses, a large number of specimens were tested. Fracture behaviour has turned out to be typical, S-shaped curve for transitional fracture at low temperatures. Apart from the other variables, specimen’s width significantly affects measured toughness. Smaller specimens, CT50, might be considered of upper bound reliability while the CT200 specimens were shown to be the most conservative. In this way it has been shown that wider specimens are more reliable in a fracture assessment of the examined steels. In this paper, the fracture probabilities of specimens in function of fracture toughness were determined as well, and it could be concluded that the widest specimens are the most likely to be broken for the same values of the fracture toughness.

Contact lenses are a common optical aid to provide help with refractive anomalies of the human eye. Construction of contact lenses is a complex engineering task as it requires knowledge of optics, materials science, production and characterization methods for product quality. Besides correcting refractive anomalies, by using contact lenses it is possible to change the characteristics of light through the manipulation of material structure properties. Nanomaterials, such as fullerene C60, are candidates for the medium that interacts with light, thus changing its properties. During material syntheses for contact lenses, fullerenes are added to the base material and optical characteristics of the new nanophotonic material are compared with the base material. The engineering, manufacture and characterization of both a commercial and a new nanophotonic contact lens is presented in this paper. The interaction of water with both base and nanophotonic contact lens materials is described. Using experimental techniques, the phenomena of an exclusion zone (EZ) is also identified.