1,721 research outputs found
Investigation of Graded La2NiO4+ Cathodes to Improve SOFC Electrochemical Performance
Mixed ionic and electronic conducting MIEC oxides are promising materials for use as cathodes in solid oxide fuel cells SOFCs due to their enhanced electrocatalytic activity compared with electronic conducting oxides. In this paper, the MIEC oxide La2NiO4+ was prepared by the sol-gel route. Graded cathodes were deposited onto yttria-stabilized zirconia YSZ pellets by dip-coating, and electrochemical impedance spectroscopy studies were performed to characterize the symmetrical cell performance. By adapting the slurries, cathode layers with different porosities and thicknesses were obtained. A ceria gadolinium oxide CGO barrier layer was introduced, avoiding insulating La2Zr2O7 phase formation and thus reducing resistance polarization of the cathode. A systematic correlation between microstructure, composition, and electrochemical performance of these cathodes has been performed. An improvement of the electrochemical performance has been demonstrated, and a reduction in the area specific resistance ASR by a factor of 4.5 has been achieved with a compact interlayer of La2NiO4+ between the dense electrolyte and the porous La2NiO4+ cathode layer. The lowest observed ASR of 0.11 cm2 at 800°C was obtained from a symmetrical cell composed of a YSZ electrolyte, a CGO interlayer, an intermediate compact La2NiO4+ layer, a porous La2NiO4+ electrode layer, and a current collection layer of platinum paste
Galaxy Cluster Scaling Relations between Bolocam Sunyaev-Zel'dovich Effect and Chandra X-ray Measurements
We present scaling relations between the integrated Sunyaev-Zel'dovich Effect
(SZE) signal, , its X-ray analogue, , and total mass, , for the 45 galaxy clusters in
the Bolocam X-ray-SZ (BOXSZ) sample. All parameters are integrated within
. values are measured using SZE data collected with
Bolocam, operating at 140 GHz at the Caltech Submillimeter Observatory (CSO).
The temperature, , and mass, , of the intracluster
medium are determined using X-ray data collected with Chandra, and is derived from assuming a constant gas mass fraction. Our
analysis accounts for several potential sources of bias, including: selection
effects, contamination from radio point sources, and the loss of SZE signal due
to noise filtering and beam-smoothing effects. We measure the
-- scaling to have a power-law index of , and
a fractional intrinsic scatter in of at fixed , both of which are consistent with previous analyses. We also measure the
scaling between and , finding a power-law index of
and a fractional intrinsic scatter in at fixed mass of
. While recent SZE scaling relations using X-ray mass proxies have
found power-law indices consistent with the self-similar prediction of 5/3, our
measurement stands apart by differing from the self-similar prediction by
approximately 5. Given the good agreement between the measured
-- scalings, much of this discrepancy appears to be caused
by differences in the calibration of the X-ray mass proxies adopted for each
particular analysis.Comment: 31 pages, 15 figures, accepted by ApJ 04/11/2015. This version is
appreciably different from the original submission: it includes an entirely
new appendix, extended discussion, and much of the material has been
reorganize
Oxford Nanopore sequencing, hybrid error correction, and de novo assembly of a eukaryotic genome
Monitoring the progress of DNA molecules through a membrane pore has been postulated as a method for sequencing DNA for several decades. Recently, a nanopore-based sequencing instrument, the Oxford Nanopore MinION, has become available, and we used this for sequencing the Saccharomyces cerevisiae genome. To make use of these data, we developed a novel open-source hybrid error correction algorithm Nanocorr specifically for Oxford Nanopore reads, because existing packages were incapable of assembling the long read lengths (5-50 kbp) at such high error rates (between approximately 5% and 40% error). With this new method, we were able to perform a hybrid error correction of the nanopore reads using complementary MiSeq data and produce a de novo assembly that is highly contiguous and accurate: The contig N50 length is more than ten times greater than an Illumina-only assembly (678 kb versus 59.9 kbp) and has >99.88% consensus identity when compared to the reference. Furthermore, the assembly with the long nanopore reads presents a much more complete representation of the features of the genome and correctly assembles gene cassettes, rRNAs, transposable elements, and other genomic features that were almost entirely absent in the Illumina-only assembly
- …