634 research outputs found
Two-step contribution to the spin-longitudinal and spin-transverse cross sections of the quasielastic (p,n) reactions
The two-step contribution to the spin-longitudinal and the spin-transverse
cross sections of ^{12}C,^{40}Ca(p,n) reactions at 494 MeV and 346 MeV is
calculated. We use a plane-wave approximation and evaluate the relative
contributions from the one-step and the two-step processes. We found that the
ratios of the two-step to the one-step processes are larger in the
spin-transverse cross sections than in the spin-longitudinal ones. Combining
these results with the distorted-wave impulse approximation (DWIA) results we
obtained considerable two-step contributions to the spin-longitudinal and the
spin-transverse cross sections. The two-step processes are important in
accounting for the underestimation of the DWIA results for the
spin-longitudinal and the spin-transverse cross sections.Comment: LaTeX 11 pages, 10 figure
Improvement of Production Rate of YBCO Coated Conductors Fabricated by TFA-MOD Method
AbstractThe metal-organic deposition (MOD) method using trifluoroacetate (TFA) salts is considered to be an effective method for inexpensively fabricating YBa2Cu3O7-y (YBCO) coated conductors with high critical current density property. The long-length TFA-MOD YBCO coated conductors have been fabricated by multi-turn reel-to-reel system. Increasing the thickness per single coating in the multi-turn reel-to-reel system is a cost-effective technique for fabrication of the precursor films in the calcination process since it reduces the number of coatings and shortens the processing time. In this work, we have developed a new starting solution consisting of non-fluorine salts of yttrium propionate and copper 2-ethylhexanoate with focusing on increasing the thickness per single coating for a high-rate fabrication of the YBCO coated conductors by the TFA-MOD method. The critical thickness per single coating of the precursor film fabricated from the new starting solution was improved to 0.44ÎŒm/coat. Furthermore, the addition of diacetoneacrylamide in the new starting solution increased the critical thickness per single coating to 0.79ÎŒm/coat. High critical current of 791 A/cm-width with high critical current density of 2.7 MA/cm2 was obtained using the new starting solution with diacetoneacrylamide at the thickness per single coating of 0.49ÎŒm/coat
Large Polarization Degree of Comet 2P/Encke Continuum Based on Spectropolarimetric Signals During Its 2017 Apparition
Spectropolarimetry is a powerful technique for investigating the physical
properties of gas and solid materials in cometary comae without mutual
contamination, but there have been few spectropolarimetric studies to extract
each component. We attempt to derive the continuum polarization degree of comet
2P/Encke, free from influence of molecular emissions. The target is unique in
that it has an orbit dynamically decoupled from Jupiter like main-belt
asteroids, while ejecting gas and dust like ordinary comets. We observed the
comet using the Higashi-Hiroshima Optical and Near-Infrared Camera attached to
the Cassegrain focus of the 150-cm Kanata telescope on UT 2017 February 21 when
the comet was at the solar phase angle of 75.7 deg. We find that the continuum
polarization degree with respect to the scattering plane is 33.8+/-2.7 % at the
effective wavelength of 0.815 um, which is significantly higher than those of
cometary dust in a high-Pmax group at similar phase angles. Assuming that an
ensemble polarimetric response of 2P/Encke's dust as a function of phase angle
is morphologically similar with those of other comets, its maximum polarization
degree is estimated to > 40 % at the phase angle of ~100 deg. In addition, we
obtain the polarization degrees of the C2 swan bands (0.51-0.56 um), the NH2
alpha bands (0.62-0.69 um) and the CN-red system (0.78-0.94 um) in a range of
3-19 %, which depend on the molecular species and rotational quantum numbers of
each branch. The polarization vector aligns nearly perpendicularly to the
scattering plane with the average of 0.4 deg over a wavelength range of
0.50-0.97 um. From the observational evidence, we conjecture that the large
polarization degree of 2P/Encke would be attributable to a dominance of large
dust particles around the nucleus, which have remained after frequent
perihelion passages near the Sun.Comment: 9 pages, 4 figures, accepted for publication in Astronomy &
Astrophysic
Torsion pairs and rigid objects in tubes
We classify the torsion pairs in a tube category and show that they are in
bijection with maximal rigid objects in the extension of the tube category
containing the Pruefer and adic modules. We show that the annulus geometric
model for the tube category can be extended to the larger category and
interpret torsion pairs, maximal rigid objects and the bijection between them
geometrically. We also give a similar geometric description in the case of the
linear orientation of a Dynkin quiver of type A.Comment: 25 pages, 13 figures. Paper shortened. Minor errors correcte
Diode-type Gas Sensors Fabricated with a Titania Film on a Ti Plate and Pd-Pt Electrodes âEffects of Polymer Coating on the Hydrogen-sensing Propertiesâ
H2 responses of a diode-type gas sensor fabricated with a TiO2 film prepared by anodization of a Ti plate and Pd-Pt electrodes (Pd-Pt/TiO2) and the effects of polymer coating on the Pd-Pt/TiO 2 sensor were investigated in this study. The H2 response of the Pd-Pt/TiO2 sensor in dry N2 was larger than that in dry air at 250°C, but the addition of moisture into the atmosphere reduced O2 concentration dependence of H2 response. The responses decreased drastically at lower temperature (50°C), but the responses in N2 were larger than those in air under both dry and wet conditions. The coating of polymer on the Pd-Pt/TiO2 sensor increased the H 2 responses in wet air and N2 and reduced O2 concentration dependence of H2 responses
Stability Assessment of Regenerated Hierarchical ZSM-48 Zeolite Designed by Post-Synthesis Treatment for Catalytic Cracking of Light Naphtha
Hierarchical ZSM-48, a one-dimensional pore system zeolite with the presence of mesopores, was obtained by post-synthesis alkaline and acid treatments. Hierarchical ZSM-48 exhibited excellent hexane cracking activity compared to parent ZSM-48, which can be attributed to better diffusion as a result of the created mesoporosity. Moreover, the post-synthesis treatment allowed for manipulation of the distribution of active sites. Consequently, better stability and higher propylene selectivity were accomplished. The spent catalyst was regenerated by removing the deposited coke from the pores, and the regenerated catalyst was characterized again to investigate the recyclability of the hierarchical structure achieved. Parent ZSM-48 showed the same textural and acidic properties after regeneration, while the structure of the post-treated sample suffered from serious defects. The defects severely decreased the number of active sites as measured by pyridine Fourier transform infrared spectroscopy and caused major structural collapse as observed by scanning electron microscopy and transmission electron microscopy
Data-based estimates of the ocean carbon sink variability â First results of the Surface Ocean pCO2 Mapping intercomparison (SOCOM)
Using measurements of the surface-ocean CO2 partial pressure (pCO2) and 14 different pCO2 mapping methods recently collated by the Surface Ocean pCO2 Mapping intercomparison (SOCOM) initiative, variations in regional and global seaâair CO2 fluxes are investigated. Though the available mapping methods use widely different approaches, we find relatively consistent estimates of regional pCO2 seasonality, in line with previous estimates. In terms of interannual variability (IAV), all mapping methods estimate the largest variations to occur in the eastern equatorial Pacific. Despite considerable spread in the detailed variations, mapping methods that fit the data more closely also tend to agree more closely with each other in regional averages. Encouragingly, this includes mapping methods belonging to complementary types â taking variability either directly from the pCO2 data or indirectly from driver data via regression. From a weighted ensemble average, we find an IAV amplitude of the global seaâair CO2 flux of 0.31 PgC yrâ1 (standard deviation over 1992â2009), which is larger than simulated by biogeochemical process models. From a decadal perspective, the global ocean CO2 uptake is estimated to have gradually increased since about 2000, with little decadal change prior to that. The weighted mean net global ocean CO2 sink estimated by the SOCOM ensemble is â1.75 PgC yrâ1 (1992â2009), consistent within uncertainties with estimates from ocean-interior carbon data or atmospheric oxygen trend
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