The thermal stability of thin films of di‐indenoperylene (DIP), an organic semiconductor is shown via thermal desorption spectroscopy (TDS) and in‐situ X‐ray diffraction to be strongly enhanced by ...aluminum oxide capping layers. Possible mechanisms for the eventual breakdown of the film (which remains crystalline up to 460 °C) at high temperatures are discussed (see Figure).
Phytoplankton composition in the mesohaline Patapsco River estuary, a tributary of Chesapeake Bay, is dominated by dinoflagellates throughout the summer. This dominance is attributed to the ...nutrient-turbulence relationships that have been described by Margalef over the last 30 yr, a field verification of this highly respected theory. The partially stratified estuary is typified by ambient nutrient concentrations higher than those in any other mesohaline area of the northern bay and its tributaries. Mean dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) concentrations in surface waters of the stratified estuary exceed 30 and 0.5 μM, respectively, during the summer, and new and regenerated nutrient loadings ensure maintenance of these high levels through the productive growing season. Turbulence levels are suggested to be low in surface waters of the stratified water column, selecting for motile dinoflagellates throughout the summer. Dinoflagellate dominance in the Patapsco River estuary is further ensured through only minor grazing pressure from low rotifer demand and low standing stocks of ambient herbivorous copepod populations, the latter group being present at levels lower than in any other mesohaline system of the Chesapeake and its tributaries. The resulting high dinoflagellate biomass appears to support a large and active microheterotrophic community (microbial loop), exemplified by abundant rotifers, high oxygen demand, and high nutrient regeneration in the water column and sediments. From these traits, the dinoflagellate-dominated mesohaline Patapsco River estuary and the tidal-fresh cyanobacteria bloom areas of the upper Potomac River appear to be analogous, with salinity defining species composition of the phytoplankton.
A short-term laboratory study was conducted to investigate the effect of barley straw in controlling several common phytoplankton and cyanobacterial species. Following a one-month incubation of ...barley straw in coarsely filtered fresh Potomac River and brackish Patuxent River waters, the growth of six autotrophic taxa was followed in culture. Barley straw slurry reduced the yield of three taxa ( Ankistrodesmus falcatus, Chlorella capsulata, Isochrysis sp.) in comparison with cultures not receiving the slurry. Although no significant changes in growth were detected with three other taxa (Cyclotella sp., Prorocentrum minimum, freshwater Pseudanabaena sp.), some patterns indicated potential impacts of the barley straw. First, a higher addition of straw to Cyclotella sp. resulted in a lower biomass accumulation than in cultures receiving lower levels. Second, the bloom-forming dinoflagellate Prorcentrum minimum was apparently stimulated at low barley straw levels, perhaps suggesting conditions associated with the straw (metals-chelation, bacterial-produced nutrients) might stimulate dinoflagellate growth. Third, species shifts were observed in two of the cultures, with barley straw favoring shifts from Isochrysis to a Cyclotella sp. - Thalassiosira sp. mixture and shifts from Pseudanabaena to a Pseudanabaena - Scenedesmus mixture. These results provide new records for the susceptibility of freshwater and brackish phytoplankton taxa to barley straw exposure, including species-specific responses and shifts in species dominance in mixed assemblages.
The BASE collaboration investigates the fundamental properties of protons and antiprotons, such as charge-to-mass ratios and magnetic moments, using advanced cryogenic Penning trap systems. In recent ...years, we performed the most precise measurement of the magnetic moments of both the proton and the antiproton, and conducted the most precise comparison of the proton-to-antiproton charge-tomass ratio. In addition, we have set the most stringent constraint on directly measured antiproton lifetime, based on a unique reservoir trap technique. Our matter/antimatter comparison experiments provide stringent tests of the fundamental charge-paritytime invariance, which is one of the fundamental symmetries of the standard model of particle physics. This article reviews the recent achievements of BASE and gives an outlook to our physics programme in the ELENA era. This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'.
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