6,524 research outputs found
Purification of Artemisinin from the Product Solution of a Semisynthetic Reaction within a Single Crystallization Step
Range and structure of ambient density from 30 to 120 km altitude
Range and structure of atmospheric density from 30 to 120 km - analysis of statistical models and deviations from U.S. standard and Patrick reference atmosphere
Preferential antiferromagnetic coupling of vacancies in graphene on SiO_2: Electron spin resonance and scanning tunneling spectroscopy
Monolayer graphene grown by chemical vapor deposition and transferred to
SiO_2 is used to introduce vacancies by Ar^+ ion bombardment at a kinetic
energy of 50 eV. The density of defects visible in scanning tunneling
microscopy (STM) is considerably lower than the ion fluence implying that most
of the defects are single vacancies. The vacancies are characterized by
scanning tunneling spectroscopy (STS) on graphene and HOPG exhibiting a peak
close to the Fermi level. The peak persists after air exposure up to 180 min,
albeit getting broader. After air exposure for less than 60 min, electron spin
resonance (ESR) at 9.6 GHz is performed. For an ion flux of 10/nm^2, we find a
signal corresponding to a g-factor of 2.001-2.003 and a spin density of 1-2
spins/nm^2. The ESR signal consists of a mixture of a Gaussian and a Lorentzian
of equal weight exhibiting a width down to 0.17 mT, which, however, depends on
details of the sample preparation. The g-factor anisotropy is about 0.02%.
Temperature dependent measurements reveal antiferromagnetic correlations with a
Curie-Weiss temperature of -10 K. Albeit the electrical conductivity of
graphene is significantly reduced by ion bombardment, the spin resonance
induced change in conductivity is below 10^{-5}.Comment: 10 pages, 5 figures, discussion on STM images in the literature of
defects in graphene adde
Scanning tunneling spectroscopy of a dilute two-dimensional electron system exhibiting Rashba spin splitting
Using scanning tunneling spectroscopy (STS) at 5 K in B-fields up to 7 T, we
investigate the local density of states of a two-dimensional electron system
(2DES) created by Cs adsorption on p-type InSb(110). The 2DES, which in
contrast to previous STS studies exhibits a 2D Fermi level, shows standing
waves at B = 0 T with corrugations decreasing with energy and with wave numbers
in accordance with theory. In magnetic field percolating drift states are
observed within the disorder broadened Landau levels. Due to the large electric
field perpendicular to the surface, a beating pattern of the Landau levels is
found and explained quantitatively by Rashba spin splitting within the lowest
2DES subband. The Rashba splitting does not contribute significantly to the
standing wave patterns in accordance with theory.Comment: 9 pages, 9 figures, submitted to Phys. Rev.
Impact of Carbon Price Policies on U.S. Industry
This paper informs the discussion of carbon price policies by examining the potential for adverse impacts on domestic industries, with a focus on detailed sector-level analysis. The assumed policy scenario involves a unilateral economy-wide $10/ton CO2 charge without accompanying border tax adjustments or other complementary policies. Four modeling approaches are developed as a proxy for the different time horizons over which firms can pass through added costs, change input mix, adopt new technologies, and reallocate capital. Overall, we find that a readily identifiable set of industries experience particularly adverse impacts as measured by reduced output and that the relative burdens on different industries are remarkably consistent across the four time horizons. Output rebounds considerably over longer time horizons, and the adverse impacts on profits diminish even more rapidly in most cases. Over the short term employment losses mirror output declines, while gains in other industries fully offset the losses over the longer horizons. At the same time, leakage abroad is considerable in some sectors, particularly when reductions in exports are considered.carbon price, competitiveness, input-output analysis
Probing electron-electron interaction in quantum Hall systems with scanning tunneling spectroscopy
Using low-temperature scanning tunneling spectroscopy applied to the
Cs-induced two-dimensional electron system (2DES) on p-type InSb(110), we probe
electron-electron interaction effects in the quantum Hall regime. The 2DES is
decoupled from p-doped bulk states and exhibits spreading resistance within the
insulating quantum Hall phases. In quantitative agreement with calculations we
find an exchange enhancement of the spin splitting. Moreover, we observe that
both the spatially averaged as well as the local density of states feature a
characteristic Coulomb gap at the Fermi level. These results show that
electron-electron interaction effects can be probed down to a resolution below
all relevant length scales.Comment: supplementary movie in ancillary file
Setting priorities for stroke care and research
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99062/1/ijs12153.pd
On the construction of evolution equations admitting a master symmetry
A method for constructing evolution equations admitting a master symmetry is proposed. Several examples illustrating the method are presented. It is also noted that for certain evolution equations master symmetries can be useful for obtaining new conservation laws from a given one
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