Andrew M. P. McDonnell

Corrosion Resistant High-Silica-Zeolite MFI Coating One General Solution Formulation for Aluminum Alloy AA-2024-T3, AA-5052-H32, AA-6061-T4, and AA-7075-T6

Corrosion resistant high-silica-zeolite (HSZ) MFI coatings have been synthesized by in situ crystallization using a single solution formulation on a series of aluminum alloys with rather different chemical compositions including AA-2024-T3, AA-5052-H32, AA-6061-T4, and AA-7075-T6. The coatings are continuous, compact, and of uniform thickness (similar to 10 mu m). The coatings are demonstrated by using ASTM D 3359B-02 method to have excellent adhesion to all metal substrates tested. The cross-sectional composition analysis shows a gradual and continuous change of Si/Al ratio from pure aluminum at the substrate surface to almost infinity at the free coating surface, and this is suggested to be the origin of excellent of adhesion observed. In addition, a simple detergent solution pretreatment is shown to be adequate for the reproducible formation of high quality coatings. (c) 2006 The Electrochemical Society.

Effects of sinking velocities and microbial respiration rates on the attenuation of particulate carbon fluxes through the mesopelagic zone

The attenuation of sinking particle fluxes through the mesopelagic zone is an important process that controls the sequestration of carbon and the distribution of other elements throughout the oceans. Case studies at two contrasting sites, the oligotrophic regime of the Bermuda Atlantic Time-series Study (BATS) and the mesotrophic waters of the west Antarctic Peninsula (WAP) sector of the Southern Ocean, revealed large differences in the rates of particle-attached microbial respiration and the average sinking velocities of marine particles, two parameters that affect the transfer efficiency of particulate matter from the base of the euphotic zone into the deep ocean. Rapid average sinking velocities of 270 ± 150 m d−1 were observed along the WAP, whereas the average velocity was 49 ± 25 m d−1 at the BATS site. Respiration rates of particle-attached microbes were measured using novel RESPIRE (REspiration of Sinking Particles In the subsuRface ocEan) sediment traps that first intercepts sinking particles then incubates them in situ. RESPIRE experiments yielded flux-normalized respiration rates of 0.4 ± 0.1 day−1 at BATS when excluding an outlier of 1.52 day−1, while these rates were undetectable along the WAP (0.01 ± 0.02 day−1). At BATS, flux-normalized respiration rates decreased exponentially with respect to depth below the euphotic zone with a 75% reduction between the 150 and 500 m depths. These findings provide quantitative and mechanistic insights into the processes that control the transfer efficiency of particle flux through the mesopelagic and its variability throughout the global oceans.

Towards a transformative understanding of the ocean’s biological pump: Priorities for future research - Report on the NSF Biology of the Biological Pump Workshop

NSF Biology of the Biological Pump Workshop, February 19–20, 2016 (Hyatt Place New Orleans, New Orleans, LA)