Microbial community response to simulated diluted bitumen spills in coastal seawater and implications for oil spill response.

Oil spills in coastal waters can have devastating impacts on local ecosystems, from the microscopic base through to mammals and seabirds. Increasing transport of diluted bitumen has led to concerns about how this novel product might impact coastal ecosystems. A mesocosm study determined that the type of diluent and the season can affect the concentrations of hydrocarbons entering the water column from a surface spill. Those same mesocosms were sampled to determine whether diluent type and season also affected the microbial response to a surface spill. Overall, there were no differences in impacts among the three types of diluted bitumen, but there were consistent responses to all products within each season. Although microbial abundances with diluted bitumen rarely differed from unoiled controls, community structure in these organisms shifted in response to hydrocarbons, with hydrocarbon-degrading bacteria becoming more abundant. The relative abundance of heterotrophic eukaryotes also increased with diluted bitumen, with few photosynthetic organisms responding positively to oil. Overall shifts in the microbial communities were minimal relative to spills of conventional oil products, with low concentrations of hydrocarbons in the water column. Oil spill response should focus on addressing the surface slick to prevent sinking or stranding to minimize ecosystem impacts.

Role of Aryl Amphiphile Hydrophobe Size on the Concentration and Stability of Graphene Nanoplatelet Dispersions.

Graphene nanoplatelets (GNPs) are stable and relatively inexpensive compared to single-layer graphene sheets and carbon nanotubes and are useful in diverse electronic, optoelectronic, and mechanical applications. Solution-state processing of the active material is desired in most of the applications mentioned above, and thus, there is great interest in increasing the concentration and stability of GNP suspension. Herein, to elucidate the role of the stabilizer structural parameters on the concentration and stability of GNP dispersions, we synthesized and used a series of aryl amphiphiles (ArAs) of varying aryl hydrophobe sizes and geometries. The ArAs were found to generate GNP dispersions with concentrations ranging from 0.05 to 0.13 mg mL-1 depending on the size of the aryl hydrophobe. The ArAs' hydrophobe size played a key role in determining the concentration of GNP suspension, while ArAs' critical aggregation concentration and solubility limits had no impact on the GNP suspension concentration. Most of the studied ArAs work similar to methylcellulose, the previously reported best performing stabilizer . Moreover, the ArAs stabilized the GNP suspension better than methylcellulose and were able to form stable dispersions for up to 6 h. Raman studies indicate that the quality of the GNPs did not degrade during the dispersion process. These findings will aid in the development of design rules for next-generation stabilizers.

Exceptional preservation and the fossil record of tetrapod integument.

The fossil record of exceptionally preserved soft tissues in Konservat-Lagerstätten provides rare yet significant insight into past behaviours and ecologies. Such deposits are known to occur in bursts rather than evenly through time, but reasons for this pattern and implications for the origins of novel structures remain unclear. Previous assessments of these records focused on marine environments preserving chemically heterogeneous tissues from across animals. Here, we investigate the preservation of skin and keratinous integumentary structures in land-dwelling vertebrates (tetrapods) through time, and in distinct terrestrial and marine depositional environments. We also evaluate previously proposed biotic and abiotic controls on the distribution of 143 tetrapod Konservat-Lagerstätten from the Permian to the Pleistocene in a multivariate framework. Gap analyses taking into account sampling intensity and distribution indicate that feathers probably evolved close to their first appearance in the fossil record. By contrast, hair and archosaur filaments are weakly sampled (five times less common than feathers), and their origins may significantly pre-date earliest known occurrences in the fossil record. This work suggests that among-integument variation in preservation can bias the reconstructed first origins of integumentary novelties and has implications for predicting where, and in what depositional environments, to expect further discoveries of exquisitely preserved tetrapod integument.