Epoxy paint failure in B-52 fuel tanks: Part II. Influence of DIEGME concentration in the fuel on the failure process

A model has been proposed to explain the failure of the original BMS10-39 epoxy paint on upper vertical surfaces in B-52 fuel tanks. The model involves interaction of the paint with DIEGME, a fuel system ice inhibitor (FSII) in jet fuel, that is distilled from the liquid fuel. In this communication, distillation experiments used to support the model are refined to better match the mass transfer of vapor from fuel in a B-52 fuel tank at close to room temperature. The interaction of these lower temperature distillates with the paint affirms the earlier model. On the basis of these experiments it is proposed that paint failure may be controlled or eliminated by reducing the level of DIEGME in the fuel. Proposed changes in military jet fuel composition are detailed.     

Optimizing the design of railway tank cars to minimize accident-caused releases

The design of vehicles transporting hazardous materials has important public safety and economic implications. Conventional wisdom among industry and government has held that a thicker tank on railroad tank cars and trucks reduces risk. However, a thicker tank increases vehicle weight and thus leads to an increase in the number of shipments required to transport the same amount of product and consequently greater exposure to accidents. In this research we develop a model that analyzes the tradeoff between increased damage resistance and greater exposure to accidents in which the objective function is minimization of the probability of release. The model accounts for the reduction in tank car release probability as a function of tank thickness, and the increased exposure to accidents that occurs due to the increased number of shipments needed for the heavier car. Three variables affecting this optimal thickness are considered in this paper: the volumetric capacity of the tank, the probability of release from other, non-tank sources, and the weight capacity of the car. Sensitivity analyses using the model indicate that for any particular configuration of tank car there is an optimal thickness. This optimal thickness is affected by several factors and there is no single optimum for all tank cars.     

A study on microstructure and properties of calcium phosphate coatings processed using ion beam assisted deposition on heated substrates

In this study a set of thin Hydroxyapatite (HA) [Ca₁₀(PO₄)₆(OH)₂] coatings was deposited on heated silicon and titanium substrates using Ion Beam Assisted Deposition (IBAD). The effects of substrate temperature and processing parameters on the microstructural properties and composition of the coatings are being studied. Analytical techniques include transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) with an energy dispersive X-ray spectroscopy (EDS), as well as scanning electron microscopy (SEM) with EDX, X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). The current results indicate that as substrate temperature increases the Ca/P ratio of the coatings both on titanium and silicon substrates increases. The crystallinity of the coatings and the number of calcium phosphate compounds within the coating including HA also increases. STEM-EDS revealed an atomically diffused intermediate layer at the interface between the coating and substrate. XRD results along with TEM selected area diffraction (SAD) revealed that the coatings are composed of HA, other calcium phosphate, and calcium oxide compounds.     

Tributary use and large-scale movements of grass carp in Lake Erie

Infrequent captures of invasive, non-native grass carp (Ctenopharyngodon idella) have occurred in Lake Erie over the last 30+ years, with recent evidence suggesting wild reproduction in the lake’s western basin (WB) is occurring. Information on grass carp movements in the Laurentian Great Lakes is lacking, but an improved understanding of large-scale movements and potential areas of aggregation will help inform control strategies and risk assessment if grass carp spread to other parts of Lake Erie and other Great Lakes. Twenty-three grass carp captured in Lake Erie’s WB were implanted with acoustic transmitters and released. Movements were monitored with acoustic receivers deployed throughout Lake Erie and elsewhere in the Great Lakes. Grass carp dispersed up to 236 km, with approximately 25% of fish dispersing greater than 100 km from their release location. Mean daily movements ranged from <0.01 to 2.49 km/day, with the highest daily averages occurring in the spring and summer. The Sandusky, Detroit, and Maumee Rivers, and Plum Creek were the most heavily used WB tributaries. Seventeen percent of grass carp moved into Lake Erie’s central or eastern basins, although all fish eventually returned to the WB. One fish emigrated from Lake Erie through the Huron-Erie Corridor and into Lake Huron. Based on our results, past assessments may have underestimated the potential for grass carp to spread in the Great Lakes. We recommend focusing grass carp control efforts on Sandusky River and Plum Creek given their high use by tagged fish, and secondarily on Maumee and Detroit Rivers.