2,037 research outputs found
Defect structure of BZCYYb17 and theoretical behavior and performance of SOFCās with BZCYYb17 electrolyte
In this work, maximum power density of SOFC with BZCYYb17(BaZr0.1Ce0.7Y0.1Yb0.1O3-d) electrolyte as the function of thickness was calculated by integrating partial conductivities of charge carriers under various DC bias conditions at a fixed oxygen chemical potential gradient at both sides of the electrolyte. The partial conductivities were calculated by fitting various total conductivities in diverse thermodynamic conditions (temperature, partial pressure of oxygen and partial pressure of vapor) using equations from defect model. From the fitting, not only we can get the partial conductivities as a function of temperature, oxygen partial pressure and hydrogen partial pressure but also mobility of each carriers and reaction constant of oxidation and hydration. Spatial distribution of oxygen chemical potential and hydrogen chemical potential across the electrolyte were calculated based on Choudhury and Pattersonās model by considering zero electrode polarization. At positive voltage conditions corresponding to SOFC and SOEC, the high conductivity region near n-type to p-type transition was expanded, but ad negative cell voltage conditions, the low conductivity region near n-type to p-type transition was expanded. The current- voltage characteristics in different conditions with temperature and thickness dependence were calculated with vapor partial pressure of each electrode is 0.03, oxygen partial pressure of the cathode 0.21 and hydrogen partial pressure of the anode 0.97
The GEOS-5 Atmospheric General Circulation Model: Mean Climate and Development from MERRA to Fortuna
This report is a documentation of the Fortuna version of the GEOS-5 Atmospheric General Circulation Model (AGCM). The GEOS-5 AGCM is currently in use in the NASA Goddard Modeling and Assimilation Office (GMAO) for simulations at a wide range of resolutions, in atmosphere only, coupled ocean-atmosphere, and data assimilation modes. The focus here is on the development subsequent to the version that was used as part of NASA s Modern-Era Retrospective Analysis for Research and Applications (MERRA). We present here the results of a series of 30-year atmosphere-only simulations at different resolutions, with focus on the behavior of the 1-degree resolution simulation. The details of the changes in parameterizations subsequent to the MERRA model version are outlined, and results of a series of 30-year, atmosphere-only climate simulations at 2-degree resolution are shown to demonstrate changes in simulated climate associated with specific changes in parameterizations. The GEOS-5 AGCM presented here is the model used for the GMAO s atmosphere-only and coupled CMIP-5 simulations
The Impact of Warm Pool El Nino Events on Antarctic Ozone
Warm pool El Nino (WPEN) events are characterized by positive sea surface temperature (SST) anomalies in the central equatorial Pacific in austral spring and summer. Previous work found an enhancement in planetary wave activity in the South Pacific in austral spring, and a warming of 3-5 K in the Antarctic lower stratosphere during austral summer, in WPEN events as compared with ENSO neutral. In this presentation, we show that weakening of the Antarctic vortex during WPEN affects the structure and magnitude of high-latitude total ozone. We use total ozone data from TOMS and OMI, as well as station data from Argentina and Antarctica, to identify shifts in the longitudinal location of the springtime ozone minimum from its climatological position. In addition, we examine the sensitivity of the WPEN-related ozone response to the phase of the quasi-biennial oscillation (QBO). We then compare the observed response to WPEN events with Goddard Earth Observing System chemistry-climate model, version 2 (GEOS V2 CCM) simulations. Two, 50-year time-slice simulations are forced by annually repeating SST and sea ice climatologies, one set representing observed WPEN events and the second set representing neutral ENSO events, in a present-day climate. By comparing the two simulations, we isolate the impact of WPEN events on lower stratospheric ozone, and furthermore, examine the sensitivity of the WPEN ozone response to the phase of the QBO
WATCHFUL OBSERVATION VERSUS EARLY AORTIC VALVE REPLACEMENT FOR SYMPTOMATIC PATIENTS WITH LOW-GRADIENT SEVERE AORTIC STENOSIS AND PRESERVED EJECTION FRACTION
Brief Communications Arising: arising from X. Dong, B. Milholland & J. Vijg Nature 538, 257ā259 (2016); doi:10.1038/nature19793. Comments by: Beer, J.A.A. de, Bardoutsos, A. & Janssen, F. (2017)
Barrier protection via Toll-like receptor 2 signaling in porcine intestinal epithelial cells damaged by deoxynivalnol
Additional file 2. IPEC-J2 cells pretreated with TLR2 ligand maintained the expression of MCP-1, GM-CSF and TLR2 against DON exposure. IPEC-J2 cells pretreated with or without TLR2 ligand for 24Ā h were exposed to DON. (A) The bar graph showed the mRNA levels of porcine mcp-1, gm-csf measured using real time-PCR at 1 and 6Ā h after DON exposure (nĀ =Ā 3). (B) The mRNA levels of porcine tlr2 were measured using real-time quantitative PCR analysis at 6Ā h. NT represents no treatment. Expression of each mRNA was presented relative to the expression of housekeeping gene, gapdh (nĀ =Ā 3). *PĀ <Ā 0.05; **PĀ <Ā 0.01; ***PĀ <Ā 0.001, determined by one-way ANOVA with Tukeyās posttest
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