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Ecosystems are degraded by transportation infrastructure partly because wildlife mortality from collisions with vehicles can threaten the viability of sensitive populations and alter ecosystem dynamics. This problem has attracted extensive study and mitigation on roads, but little similar work has been done for railways despite the occurrence of wildlife–train collisions worldwide. We propose a method for reducing wildlife losses on railways by providing animals with warning signals that are triggered by approaching trains, particularly in areas of high strike risk. Analogous to the warning signals provided for people at road–rail crossings, our system emits flashes of light and bell sounds approximately 20 s before train arrival at the location where the system is deployed. Learning theory predicts that animals will associate these warning signals with train arrival if the warning signal (conditioned stimulus) consistently precedes train arrival (unconditioned stimulus). We tested two designs for a warning system: one that detects passing trains and wirelessly relays this information to warning devices further along the track, and one that integrates detection of trains at a distance with warning signals in a single device. The most reliable design detected passing trains with magnetic or vibration sensors and relayed the information to warning devices. We have developed an affordable and publicly available prototype of this design that can be built for a material cost of US$225. With refinement, this technology could become an inexpensive means of protecting wildlife and people around the world from fatal train strikes wherever strike risk is known or predicted to be unusually high. [ABSTRACT FROM AUTHOR]

Abstract: Porous titanium alloy-bioactive glass composite coatings were manufactured via the flame spray deposition process. The porous coatings, targeted for orthodontic and bone-fixation applications, were made from bioactive glass (45S5) powder blended with either commercially pure titanium (Cp-Ti) or Ti-6Al-4V alloy powder. Two sets of spray conditions, two metallic particle size distributions, and two glass particle size distributions were used for this study. Negative control coatings consisting of pure Ti-6Al-4V alloy or Cp-Ti were sprayed under both conditions. The as-sprayed coatings were characterized through quantitative optical cross-sectional metallography, X-ray diffraction (XRD), and ASTM Standard C633 tensile adhesion testing. Determination of the porosity and glassy phase distribution was achieved by using image analysis in accordance with ASTM Standard E2109. Theoretical thermodynamic and heat transfer modeling was conducted to explain experimental observations. Thermodynamic modeling was performed to estimate the flame temperature and chemical environment for each spray condition and a lumped capacitance heat transfer model was developed to estimate the temperatures attained by each particle. These models were used to establish trends among the choice of alloy, spray condition, and particle size distribution. The deposition parameters, alloy composition, and alteration of the feedstock powder size distribution had a significant effect on the coating microstructure, porosity, phases present, mechanical response, and theoretical particle temperatures that were attained. The most promising coatings were the Ti-6Al-4V-based composite coatings, which had bond strength of 20±2MPa (n =5) and received reinforcement and strengthening from the inclusion of a glassy phase. It was shown that the use of the Ti-6Al-4V-bioactive glass composite coatings may be a superior choice due to the possible osteoproductivity from the bioactive glass, the potential ability to support tissue ingrowth and vascular tissue, and the comparable strength to similar coatings. [Copyright &y& Elsevier]

The formation of α-Al2O3 upon thermal oxidation of Al containing alloys is accompanied by growth stresses and distortions. Experiments that demonstrate and measure these phenomena have been devised. A model that predicts the distortions and the stresses has been developed, which incorporates new oxide formation on grain boundaries within the α-Al2O3, as well as redistribution of the induced stresses by plastic deformation. In this study, a quantitative comparison is made between measurements and predictions by analyzing oxide formation around a surface groove in an FeCrAlY substrate. The changes in the shape of the groove caused by cyclic oxidation are characterized and the stresses induced in the oxide that forms around the groove are measured using piezospectroscopy. Simulations are conducted using the independently known thermo-mechanical properties of the alloy and the α-Al2O3. Direct comparisons between the measurements and simulations are used to validate the model. [Copyright &y& Elsevier]

When thin sections of FeCrAlY alloys having initially flat surfaces are oxidized at high temperature, the surface becomes uneven as some metal grains on the surface displace above and below the macroscopic surface. On subsequent cooling, the oxide formed by high-temperature oxidation cracks and spalls at the edges of the uplifted grains. Microstructural observations indicate that the grain uplift is associated with grain sliding and it proposed that the sliding at the oxidation temperature occurs in response to the evolving compressive growth stress in the oxide. The observed spalling patterns are consistent with a fracture mechanics model in which incipient flaws at the oxide-alloy interface, in the vicinity of the step edges, propagate in the residual stress field in the oxide. [Copyright &y& Elsevier]

This study evaluated how the flexural strength of a zirconia-based ceramic (Y-TZP) was affected by air abrasion with 30 μm SiO on both zirconia surfaces: the cementation surface, and the veneering surface. Translucent Y-TZP ceramic bars, for four-point bend testing, were prepared and divided considering the compressive (surface treatment for cementation) and tensile surfaces (surface treatment for veneering). Sandblasting was performed or not for each compressive and tensile surfaces. The specimens from all experimental conditions were analysed by SEM. All specimens were tested in four-point bending. Data were statistically analysed using one-way ANOVA and Post Hoc tests (α= 0.05). A Weibull analysis was used to analyse the strength reliability. According to the results of this investigation, the flexural strength was significantly affected by sandblasting on both surfaces: for veneering (P < 0.001) and for cementation (P < 0.001). Sandblasting the veneering surface, to improve bonding of the veneer to Y-TZP, negatively impacted strength reliability. Sandblasting the cementation surface decreased the flexural strength while increasing the strength reliability. [ABSTRACT FROM AUTHOR]