3,062 research outputs found
Hydroxylation of Platinum Surface Oxides Induced by Water Vapor
With its high stability and well-tuned binding strength for adsorbates, platinum is an excellent catalyst for a wide range of reactions. In applications like car exhaust purification, the oxidation of hydrocarbons, and fuel cells, platinum is exposed to highly oxidizing conditions, which often leads to the formation of surface oxides. To reveal the structure of these surface oxides, the oxidation of Pt in O2 has been widely studied. However, in most applications, H2O is also an important or even dominant part of the reaction mixture. Here, we investigate the interaction of H2O with Pt surface oxides using near-ambient-pressure X-ray photoelectron spectroscopy. We find that reversible hydroxylation readily occurs in H2O/O2 mixtures. Using time-resolved measurements, we show that O–OH exchange occurs on a time scale of seconds
Classification of double flag varieties of complexity 0 and 1
A classification of double flag varieties of complexity 0 and 1 is obtained.
An application of this problem to decomposing tensor products of irreducible
representations of semisimple Lie groups is considered
Dark Energy Accretion onto a Black Hole in an Expanding Universe
By using the solution describing a black hole embedded in the FLRW universe,
we obtain the evolving equation of the black hole mass expressed in terms of
the cosmological parameters. The evolving equation indicates that in the
phantom dark energy universe the black hole mass becomes zero before the Big
Rip is reached.Comment: 7 pages, no figures, errors is correcte
A 3D radiative transfer framework: VII. Arbitrary velocity fields in the Eulerian frame
A solution of the radiative-transfer problem in 3D with arbitrary velocity
fields in the Eulerian frame is presented. The method is implemented in our 3D
radiative transfer framework and used in the PHOENIX/3D code. It is tested by
comparison to our well- tested 1D co-moving frame radiative transfer code,
where the treatment of a monotonic velocity field is implemented in the
Lagrangian frame. The Eulerian formulation does not need much additional memory
and is useable on state-of-the-art computers, even large-scale applications
with 1000's of wavelength points are feasible
Spherical orbit closures in simple projective spaces and their normalizations
Let G be a simply connected semisimple algebraic group over an algebraically
closed field k of characteristic 0 and let V be a rational simple G-module of
finite dimension. If G/H \subset P(V) is a spherical orbit and if X is its
closure, then we describe the orbits of X and those of its normalization. If
moreover the wonderful completion of G/H is strict, then we give necessary and
sufficient combinatorial conditions so that the normalization morphism is a
homeomorphism. Such conditions are trivially fulfilled if G is simply laced or
if H is a symmetric subgroup.Comment: 24 pages, LaTeX. v4: Final version, to appear in Transformation
Groups. Simplified some proofs and corrected minor mistakes, added
references. v3: major changes due to a mistake in previous version
Research study of some RAM antennas Final report, 18 Nov. 1964 - 18 Jun. 1965
Input impedance and radiation pattern determinations for cylindrical gap, waveguide excited and circular waveguide slot antenna array
Bayesian model-independent evaluation of expansion rates of the universe
Marginal likelihoods for the cosmic expansion rates are evaluated using the
`Constitution' data of 397 supernovas, thereby updating the results in some
previous works. Even when beginning with a very strong prior probability that
favors an accelerated expansion, we obtain a marginal likelihood for the
deceleration parameter peaked around zero in the spatially flat case. It
is also found that the new data significantly constrains the cosmographic
expansion rates, when compared to the previous analyses. These results may
strongly depend on the Gaussian prior probability distribution chosen for the
Hubble parameter represented by , with . This and similar
priors for other expansion rates were deduced from previous data. Here again we
perform the Bayesian model-independent analysis in which the scale factor is
expanded into a Taylor series in time about the present epoch. Unlike such
Taylor expansions in terms of redshift, this approach has no convergence
problem.Comment: To appear in Astrophysics and Space Scienc
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