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The coefficient of restitution (COR) is one of the most important standards in all bat-and-ball sports to study the ball suitability and bouncing characteristics. Currently, a demand exists for an improved analytical model for computing the COR, particularly when a new material is introduced. A viscoelastic ball known as a sliotar is taken from the Irish bat-and-ball sport of hurling and used in this paper as a case study. For the theoretical approach, a modified Maxwell's viscoelastic model was used to derive an analytical formula to predict the COR. The developed formula confirms that the damping ratio and the dependency of the COR on the impact speed are the most dominant factors. A 3-dimensional finite element (FE) model was developed to simulate the sliotar impact test to estimate the COR, and to provide a simple tool for further studies on the sliotar. A high-speed camera was used to film the impact event to validate the models' behavior. The close correlation of 9% and 5% between the experimental and the developed analytical and FE models, respectively, indicates that the developed models can successfully identify the COR of the ball in the game of hurling and similar bat-and-ball sports. [ABSTRACT FROM PUBLISHER]

Municipal effluents have been shown to contain a cocktail of endocrine disrupting chemicals (EDCs). The estrogenic effect of these effluents has been demonstrated on both vertebrate and invertebrate species by the feminisation of the exposed males. This effect was investigated on the freshwater zebra mussel (Dreissena polymorpha) after exposure to tertiary treated effluent from a municipal sewage treatment works (STW). Mussels were exposed to the effluent in situ for 112 days during gametogenesis (December to mid-March). Levels of vitellin (Vn)-like proteins (the major protein found in oocytes) were measured indirectly using the alkali-labile phosphate (ALP) technique and confirmed by gel electrophoresis. Significant increases (P < 0.05) in Vn-like proteins were found in both male and female mussels after exposure to the effluent, indicating that endocrine disruption (ED) had occurred. Using High-performance thin layer chromatography (HPTLC) levels of the mussels main steroid, cholesterol were found to more than double after effluent exposure. General physiological (survival, condition, etc.) and histological effects were also investigated. Histological effects observed included a large increase in interstitial tissue between the seminiferous tubules of the gonad in male mussels exposed to effluent. Effluent samples were tested for estrogenic compounds using the toxicity identification and evaluation method (TIE). A complex mixture of compounds with estrogenic activity was found with 17beta-estradiol, 17alpha-ethynlestradiol and bisphenol A accounting for the majority of the effluents estrogenic activity. Results indicate that the zebra mussel is a suitable bioindicator of endocrine disruption in freshwater environments.