The United States Department of Energy (DOE) projects an estimated energy cost savings of $630 billion from 2015 to 2035 if reliable solid-state lighting technologies can be developed and DOE goals are met. [1] For the cost-effective implementation of light-emitting diodes (LEDs), development of new inexpensive light emitters is an urgent need. Owing to their outstanding photophysical properties including tunable bandgaps and emission colors, high photoluminescent quantum yields (PLQY) and excellent color purity, metal halide perovskite LEDs (PeLEDs)

The upper Tennessee River Basin contains the highest density of our nation's caves; yet, little is known regarding speleogenesis or Fe and Mn biomineralization in these predominantly epigenic systems. Mn:Fe ratios of Mn and Fe oxide-rich biofilms, coatings, and mineral crusts that were abundant in several different caves ranged from ca. 0.1 to 1.0 as measured using ICP-OES. At sites where the Mn:Fe ratio approached 1.0 this represented an order of magnitude increase above the bulk bedrock ratio, suggesting that biomineralization processes play an important role in the formation of these cave ferromanganese deposits. Estimates of total bacterial SSU rRNA genes in ferromanganese biofilms, coatings, and crusts measured approximately 7×10 7 -9×10 9 cells/g wet weight sample. A SSU-rRNA based molecular survey of biofilm material revealed that 21% of the 34 recovered dominant (non-singleton) OTUs were closely related to known metal-oxidizing bacteria or clones isolated from oxidized metal deposits. Several different isolates that promote the oxidation of Mn(II) compounds were obtained in this study, some from high dilutions (10 ) of deposit material. In contrast to studies of caves in other regions, SSU rRNA sequences of Mn-oxidizing bacterial isolates in this study most closely matched those of Pseudomonas, Leptothrix, Flavobacterium, and Janthinobacterium. Combined data from geochemical analyses, molecular surveys, and culture-based experiments suggest that a unique consortia of Mn(II)-oxidizing bacteria are abundant and promoting biomineralization processes within the caves of the upper Tennessee River Basin.

Summary Foliar fungal endophytes are one of the most diverse guilds of symbiotic fungi found in the photosynthetic tissues of every plant lineage, but it is unclear how plant environments and leaf resource availability shape their diversity. We explored correlations between leaf nutrient availability and endophyte diversity among Pinus muricata and Vaccinium ovatum plants growing across a soil nutrient gradient spanning a series of coastal terraces in Mendocino, California. Endophyte richness decreased in plants with higher leaf nitrogen‐to‐phosphorus ratios for both host species, but increased with sodium, which may be toxic to fungi at high concentrations. Isolation frequency, a proxy of fungal biomass, was not significantly predicted by any of the same leaf constituents in the two plant species. We propose that stressed plants can exhibit both low foliar nutrients or high levels of toxic compounds, and that both of these stress responses predict endophyte species richness. Stressful conditions that limit growth of fungi may increase their diversity due to the suppression of otherwise dominating species. Differences between the host species in their endophyte communities may be explained by host specificity, leaf phenology, or microclimates.

Anthropogenic impact is a pervasive problem in heavily trafficked cave systems and fecal contamination is equally problematic in many cave and karst waters worldwide.

Artificial climbing walls represent a unique indoor environment in which humans interact closely with a variety of surface types. Climbing wall holds may mediate transmission of organisms between individuals, and yet there are no studies that identify microorganisms present on these surfaces. In the current study, the microorganisms found on climbing wall holds were characterized by analysis of amplified SSU rRNA gene sequences. In contrast to many other studies of built environments, the majority of microorganisms on holds were most closely related to microbes annotated as being recovered from environmental sources, such as soil, with human skin also representing an important source. Regional patterns were evident as rRNA gene sequences from the marine cyanobacterium Prochlorococcus were abundant in gyms found within 16 km of the ocean. Enterobacteriaceae were present on 100 % of holds surveyed, and the members detected are commonly associated with fecal matter.