572 research outputs found
Pyrolysis-Catalytic-Dry Reforming of Waste Plastics and Mixed Waste Plastics for Syngas Production
The CO2 dry reforming of various types of waste plastics (LDPE, HDPE, PS, PET, and PP) and a simulated mixture of the different waste plastics was investigated over a Ni–Co–Al catalyst using a two-stage reactor. The first stage pyrolyzed the plastics, and the second stage involved catalytic-dry reforming of the product pyrolysis gases with CO2. The introduction of CO2 without a catalyst markedly increased the dry reforming reaction and significantly improved the production of H2/CO synthesis gas (syngas). The introduction of the Ni–Co–Al catalyst further significantly improved the production of syngas. LDPE produced the highest yield of syngas at 154.7 mmolsyngas g–1plastic from the pyrolysis-catalytic-dry reforming process. The order of syngas production for the different plastics was LDPE < HDPE < PP < PS < PET. The syngas yield from the processing of the simulated waste plastic mixture was 148.6 7 mmolsyngas g–1plastic which reflected the high content of the linear polyalkene plastics (LDPE, HDPE, PP) in the simulated waste plastic mixture
Infinite Layer LaNiO(2): Ni(1+)is not Cu(2+)
The Ni ion in LaNiO has the same formal ionic configuration as
does Cu in isostructural CaCuO, but it is reported to be nonmagnetic and
probably metallic whereas CaCuO is a magnetic insulator. From ab initio
calculations we trace its individualistic behavior to (1) reduced
mixing due to an increase of the separation of site energies () of at least 2 eV, and (2) important Ni mixing with
La states that leads to Fermi surface pockets of La
character that hole-dope the Ni 3d band.Correlation effects do not appear to be
large in LaNiO. However, ad hoc increase of the intraatomic repulsion on
the Ni site (using the LDA+U method) is found to lead to a novel correlated
state: (i) the transition metal and states undergo
consecutive Mott transitions, (ii) their moments are antialigned leading
(ideally) to a "singlet" ion in which there are two polarized orbitals, and
(iii) mixing of the upper Hubbard band with the La
states leaves considerable transition metal 3d character in a band pinned to
the Fermi level. The magnetic configuration is more indicative of a Ni
ion in this limit, although the actual charge changes little with U.Comment: 7 pages, 8 figure
A Stringent Limit on the Accretion Luminosity of the Possible Central Black Hole in the Globular Cluster M15
The globular cluster M15 has recently been found to host a possible central
black hole with a mass of ~2000 solar masses. A deep, high-resolution Chandra
image failed to detect the "nucleus" of the cluster in X-rays. The upper limit
on the X-ray luminosity (L_x < 5.6x10^32 erg/s) corresponds to a bolometric
Eddington ratio of L_bol/L_Edd < (2-4)x10^-8. Combining this limit with an
estimate of the electron density of the intracluster ionized plasma derived
from pulsar dispersion measures, we show that the radiative efficiency of the
accretion flow, if it accretes at the Bondi rate, must be much lower than that
of a standard optically thick, geometrically thin disk.Comment: To appear in ApJ (Letters). 4 page
Neurology
Contains reports on six research projects.Public Health Service (B-3055, B-3090)United States Air Force (AF33(616)-7282, AF49(638)-1130)United States Navy, Office of Naval Research (Nonr-609(39))United States Army Chemical Corps (DA-18-108-405-Cml-942)National Science Foundation (Grant G-16526
MOA 2003-BLG-37: A Bulge Jerk-Parallax Microlens Degeneracy
We analyze the Galactic bulge microlensing event MOA-2003-BLG-37. Although
the Einstein timescale is relatively short, t_e=43 days, the lightcurve
displays deviations consistent with parallax effects due to the Earth's
accelerated motion. We show that the chi^2 surface has four distinct local
minima that are induced by the ``jerk-parallax'' degeneracy, with pairs of
solutions having projected Einstein radii, \tilde r_e = 1.76 AU and 1.28 AU,
respectively. This is the second event displaying such a degeneracy and the
first toward the Galactic bulge. For both events, the jerk-parallax formalism
accurately describes the offsets between the different solutions, giving hope
that when extra solutions exist in future events, they can easily be found.
However, the morphologies of the chi^2 surfaces for the two events are quite
different, implying that much remains to be understood about this degeneracy.Comment: 19 pages, 3 figures, 1 table, ApJ, in press, 1 July 200
Probing the atmosphere of a solar-like star by galactic microlensing at high magnification
We report a measurement of limb darkening of a solar-like star in the very
high magnification microlensing event MOA 2002-BLG-33. A 15 hour deviation from
the light curve profile expected for a single lens was monitored intensively in
V and I passbands by five telescopes spanning the globe. Our modelling of the
light curve showed the lens to be a close binary system whose centre-of-mass
passed almost directly in front of the source star. The source star was
identified as an F8-G2 main sequence turn-off star. The measured stellar
profiles agree with current stellar atmosphere theory to within ~4% in two
passbands. The effective angular resolution of the measurements is <1
micro-arcsec. These are the first limb darkening measurements obtained by
microlensing for a Solar-like star.Comment: Accepted for publication in A&A Letters. 5 pages, 2 embedded colour
ps figures plus 1 jpg figure. Version with all figures embedded available
from: http://www.roe.ac.uk/~iab/moa33paper
Inorbit Performance of the Hard X-ray Telescope (HXT) on board the Hitomi (ASTRO-H) satellite
Hitomi (ASTRO-H) carries two Hard X-ray Telescopes (HXTs) that can focus
X-rays up to 80 keV. Combined with the Hard X-ray Imagers (HXIs) that detect
the focused X-rays, imaging spectroscopy in the high-energy band from 5 keV to
80 keV is made possible. We studied characteristics of HXTs after the launch
such as the encircled energy function (EEF) and the effective area using the
data of a Crab observation. The half power diameters (HPDs) in the 5--80 keV
band evaluated from the EEFs are 1.59 arcmin for HXT-1 and 1.65 arcmin for
HXT-2. Those are consistent with the HPDs measured with ground experiments when
uncertainties are taken into account. We can conclude that there is no
significant change in the characteristics of the HXTs before and after the
launch. The off-axis angle of the aim point from the optical axis is evaluated
to be less than 0.5 arcmin for both HXT-1 and HXT-2. The best-fit parameters
for the Crab spectrum obtained with the HXT-HXI system are consistent with the
canonical values.Comment: 13 pages, 5 figures; the acknowledgment was modifie
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