Arbuscular mycorrhizae in thermal-influenced soils in Yellowstone National Park

Mycorrhizae are common plant-fungal symbioses occurring in most land plants. Despite their ubiquity, little is known about the distribution of arbuscular mycorrhizae (AM) in extreme environments. We surveyed for the presence of AM in thermal sites in Yellowstone National Park (YNP) where soils are characterized by extreme pHs, elevated temperatures, and toxic element concentrations. Plants at 5 sites, growing in soils with rooting-zone temperatures up to 48°C and soil pH values as low as 3.4, were mycorrhizal (colonization levels from 4% to 34%). Soils from a sparsely vegetated thermal area and an adjacent, continuously vegetated transition area differed significantly in rooting-zone temperature (35°C vs. 26°C), acidity (pH 3.8 vs. 5.4), electrical conductivity (2.22 vs. 0.49 mmhos cm -1 ), Fe (181.3 vs. 48.5 mg kg -1 ),Mn (7.2 vs. 98.2 mg kg -1 ), and Zn (2.3 vs. 4.5 mg kg -1 ). Mycorrhizal infectivity potential (MIP) was 77% greater in the transition soils, with colonization levels of 26% and 46% in thermal and transition soils, respectively. Furthermore, colonization of Agrostis scabra , Dichanthelium lanuginosum , and Mimulus guttatus was found to be consistently high throughout the growing season (from 48% to 72%). It is possible that AM are essential for plant life on the edge of thermal areas, and that either or both symbionts are specifically adapted to their environment. Further research is required to elucidate AM function in and specific adaptations to YNP's thermal areas.     

Recent Advances in Hard, Tough, and Low Friction Nanocomposite Coatings

Nanocomposite coatings demonstrate improved friction and wear responses under severe sliding conditions in extreme environments. This paper provides a review how thin film multilayers and nanocomposites result in hard, tough, low-friction coatings. Approaches to couple multilayered and nanocomposite materials with other surface engineering strategies to achieve higher levels of performance in a variety of tribological applications are also discussed. Encapsulating lubricious phases in hard nanocomposite matri- ces is one approach that is discussed in detail. Results from state-of-the-art ＂chameleon＂ nanocomposites that exhibit reversible adaptability to ambient humidity or temperature are presented.