1,044 research outputs found
Effect of lift force on the aerodynamics of dust grains in the protoplanetary disk
We newly introduce lift force into the aerodynamics of dust grains in the
protoplanetary disk. Although many authors have so far investigated the effects
of the drag force, gravitational force and electric force on the dust grains,
the lift force has never been considered as a force exerted on the dust grains
in the gas disk. If the grains are spinning and moving in the fluid, then the
lift force is exerted on them. We show in this paper that the dust grains can
be continuously spinning due to the frequent collisions so that the lift force
continues to be exerted on them, which is valid in a certain parameter space
where the grain size is larger than ~ 1 m and where the distance from the
central star is larger than 1 AU for the minimum mass solar nebula. In
addition, we estimate the effects of the force on the grain motion and obtain
the result that the mean relative velocity between the grains due to the lift
force is comparable to the gas velocity in the Kepler rotational frame when the
Stokes number and lift-drag ratio are both ~ 1. This estimation is performed
under the assumptions of the steady state and the isotropic spin angular
momentum. We also estimate the mean relative velocity when the grains keep
spinning and conclude that the lift force marginally affects the mean relative
velocity in the minimum mass solar nebula. If there is a grain-concentrated
part in the disk, the relative velocity due to the lift force may dominate
there because of high collision rate.Comment: 9 pages, 4 figures. Accepted for publication in Earth, Planets and
Spac
Current Reflection and Transmission at Conformal Defects Applying BCFT to Transport Process
International audienceWe study reflection/transmission process at conformal defects by introducing new transport coefficients for conserved currents. These coefficients are defined by using BCFT techniques thanks to the folding trick, which turns the conformal defect into the boundary. With this definition, exact computations are demonstrated to describe reflection/transmission process for a class of conformal defects. We also compute the boundary entropy based on the boundary state
Support for Local Educational Expenditures by the Elderly : Evidence from Japan
投稿論文Refereed Articl
Safety and effectiveness of controlled-release paroxetine in routine clinical practice: results of a postmarketing surveillance study of patients with depression
Time Resolved Investigation of Fast Phase- Change Phenomena in Rewritable Optical Recording Media
Caffeic acid inhibits the formation of 1-hydroxyethyl radical in the reaction mixture of rat liver microsomes with ethanol partly through its metal chelating activity
Effect of caffeic acid on the formation of 1-hydroxyethyl radicals via the microsomal ethanol-oxidizing system pathway was examined. The electron spin resonance spin trapping showed that 1-hydroxyethyl radicals form in the control reaction mixture which contained 0.17 M ethanol, 1 mg protein/ml rat river microsomes, 0.1 M α-(4-pyridyl-1-oxide)-N-tert-butylnitrone, 5 mM nicotinamide adenine dinucleotide phosphate and 30 mM phosphate buffer (pH 7.4). When the electron spin resonance spectra of the control reaction mixtures with caffeic acid were measured, caffeic acid inhibited the formation of 1-hydroxyethyl radicals in a concentration dependent manner. Gallic acid, dopamine, l-dopa, chlorogenic acid and catechin also inhibited the formation of 1-hydroxyethyl radicals. Above results indicated that the catechol moiety is essential to the inhibitory effect. Caffeic acid seems to chelate of iron ion at the catechol moiety. Indeed, the inhibitory effect by caffeic acid was greatly diminished in the presence of desferrioxamine, a potent iron chelator which removes iron ion in the Fe (III)-caffeic acid complex. Since Fe (III)-desferrioxamine complex is active for the 1-hydroxyethyl radicals formation, caffeic acid inhibits the formation of 1-hydroxyethyl radicals in the reaction mixture partly through its metal chelating activity
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