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Manipulating surface charge, electric field, and plasma afterglow in a non-equilibrium plasma is critical to control plasma-surface interaction for plasma catalysis and manufacturing. Here, we show enhancements of surface charge, electric field during breakdown, and afterglow by ferroelectric barrier discharge. The results show that the ferroelectrics manifest spontaneous electric polarization to increase the surface charge by two orders of magnitude compared to discharge with an alumina barrier. Time-resolved in-situ electric field measurements reveal that the fast polarization of ferroelectrics enhances the electric field during the breakdown in streamer discharge and doubles the electric field compared to the dielectric barrier discharge. Moreover, due to the existence of surface charge, the ferroelectric electrode extends the after-glow time and makes discharge sustained longer when alternating the external electric field polarity. The present results show that ferroelectric barrier discharge offers a promising technique to tune plasma properties for efficient plasma catalysis and electrified manufacturing. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is essential for productivity of alpine grassland ecosystems, which are sensitive to global warming. We tested the hypotheses that (1) mobilized 'calcium-bound inorganic P' (Ca-Pi) is a major source of plant-available P in alpine meadows with alkaline soils after long-term warming, (2) mobilization of Ca-Pi is linked to effective plant carboxylate-releasing P-acquisition strategies under warming, and (3) the mobilization is also related to plant nitrogen (N)-acquisition. We conducted an 8-year warming experiment in an alpine meadow (4635 m above sea level) on the Qinghai-Tibetan Plateau. A significant increase in P concentration in both aboveground and belowground biomass indicates an increased mobilization and assimilation of P by plants under warming. We observed a significant decrease in Ca-Pi, no change in moderately-labile organic P, and an increase in highly resistant organic P after warming. There was no increase in phosphatase activities. Our results indicate that Ca-Pi, rather than organic P was the major source of plant-available P for alpine meadows under warming. Higher leaf manganese concentrations of sedges and forbs after warming indicate that carboxylates released by these plants are a key mechanism of Ca-Pi mobilization. The insignificant increase in Rhizobiales after warming and the very small cover of legumes show a minor role of N-acquisition strategies in solubilizing phosphate. The insignificant change in relative abundance of mycorrhizal fungi and bacteria related to P cycling after warming shows a small contribution of microorganisms to Ca-Pi mobilization. The significant increase in leaf N and P concentrations and N:P ratio of grasses and no change in sedge leaf N:P ratio reflect distinct responses of plant nutrient status to warming due to differences in P-acquisition strategies. We highlight the important effects of belowground P-acquisition strategies, especially plant carboxylate-releasing P-acquisition strategies on responses of plants to global changes in alpine meadows. [ABSTRACT FROM AUTHOR]

General-purpose processors are often incapable of achieving the challenging cost, performance, and power demands of high-performance applications. To meet these demands, most systems employ a number of hardware accelerators to off-load the computationally demanding portions of the application. As an alternative to this strategy, we examine customizing the computation capabilities of a processor for a particular application. The processor is extended with hardware in the form of a set of custom function units and instruction set extensions. To effectively identify opportunities for creating custom hardware, a dataflow graph design space exploration engine heuristically identifies candidate computation subgraphs without artificially constraining their size or shape. The engine combines estimates of performance gain, cost, and inherent limitations of the processor to grow candidate graphs in profitable directions while pruning unprofitable paths. This paper describes the dataflow graph exploration engine and evaluates its effectiveness across a set of embedded applications. [ABSTRACT FROM AUTHOR]

The control of plasma instability of weakly ionized plasma in a reactive flow is of great importance in plasma-assisted combustion, catalysis, fuel reforming and material synthesis. In this work, we propose a new concept of plasma chemical instability and analyze the mechanisms and impact of plasma chemical instability on the transition from a uniform discharge to a contracted state of a self-sustained glow discharge in a reactive H2–O2–N2 mixture. A one-dimensional numerical model for plasma chemical instability was developed which accounted for convective heat loss, Joule heating of plasma, and major non-equilibrium plasma-assisted combustion kinetic pathways including electron-impact ionization, vibrational energy transfer, electron attachment, combustion reactions, and heat release. The results showed that plasma chemical instability significantly modified the onset plasma current of plasma thermal instability. Specifically, the critical condition of the instability transition was strongly influenced by electron-impact reactant ionization, electron attachment to oxygen, endothermic/exothermic chemical reactions, and the formation of reaction products. [ABSTRACT FROM AUTHOR]