In the case reported, herpes virus I after having caused relapsing keratitis in an eye promoted the formation of a severe corneal ulcer caused by Scopulariopsis brevicaulis, a saprophytic mycete found in soil, which only once has been described as the cause of keratitis in man. Scopulariopsis was identified microscopically after culturing the conjunctival secretion on Sabouraud dextrose agar medium, while DNA probe tests confirmed the absence of herpes virus I. Topical and oral administration of miconazole and scraping of the corneal infiltrate dispersed the infection. Subsequently local steroids were given to reduce the neo-vascularization, and a therapeutic contact lens was applied because of intercurrent corneal thinning. Three months after beginning antifungal therapy, the visual acuity had increased from 1/120 to 1/10. The case described confirms that S. brevicaulis can cause opportunist infections in a cornea previously damaged by a different agent.
Finding an accurate stress-strain relation, able to describe the mechanical behavior of metals during forming and machining processes, is an important challenge in several fields of mechanics, with significant repercussions in the technological field. Indeed, in order to predict the real mechanical behavior of materials, constitutive laws must be able to take into account elastic, viscous and plastic phenomena. Most constitutive models are based on empirical evidence and/or theoretical approaches, and provide a good prediction of the mechanical behavior of several materials.Here we present a non linear stress-strain relation based on fractional operators. The proposed constitutive law is based on integral formulation, and takes into account the viscoelastic behavior of the material and the inelastic phenomenon that appears when the stress reaches a particular yielding value. A specific case of the proposed constitutive law for imposed strain history is used to fit experimental data obtained from tensile tests on two kind of metal alloys. A best-fitting procedure demonstrates the accuracy of the proposed stress-strain relation and its results are compared to those obtained with some classical models. We conclude that the proposed model provides the best results in predicting the mechanical behavior for low and high values of stress/strain.
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