10,404 research outputs found
Quantum anomalous vortex and Majorana zero mode in iron-based superconductor Fe(Te,Se)
In topological insulators doped with magnetic ions, spin-orbit coupling and
ferromagnetism give rise to the quantum anomalous Hall effect. Here we show
that in s-wave superconductors with strong spin-orbit coupling, magnetic
impurity ions can generate topological vortices in the absence of external
magnetic fields. Such vortices, dubbed quantum anomalous vortices, support
robust Majorana zero-energy modes when superconductivity is induced in the
topological surface states. We demonstrate that the zero-energy bound states
observed in Fe(Te,Se) superconductors are possible realizations of the Majorana
zero modes in quantum anomalous vortices produced by the interstitial magnetic
Fe. The quantum anomalous vortex matter not only advances fundamental
understandings of topological defect excitations of Cooper pairing, but also
provides new and advantageous platforms for manipulating Majorana zero modes in
quantum computing.Comment: final version, 8 pages, 3 figures + supplemental materia
The dependence of tidal stripping efficiency on the satellite and host galaxy morphology
In this paper we study the tidal stripping process for satellite galaxies
orbiting around a massive host galaxy, and focus on its dependence on the
morphology of both satellite and host galaxy. For this purpose, we use three
different morphologies for the satellites: pure disc, pure bulge and a mixture
bulge+disc. Two morphologies are used for the host galaxies: bulge+disc and
pure bulge. We find that while the spheroidal stellar component experiences a
constant power-law like mass removal, the disc is exposed to an exponential
mass loss when the tidal radius of the satellite is of the same order of the
disc scale length. This dramatic mass loss is able to completely remove the
stellar component on time scale of 100 Myears. As a consequence two satellites
with the same stellar and dark matter masses, on the same orbit could either
retain considerable fraction of their stellar mass after 10 Gyrs or being
completely destroyed, depending on their initial stellar morphology. We find
that there are two characteristic time scales describing the beginning and the
end of the disc removal, whose values are related to the size of the disc. This
result can be easily incorporated in semi-analytical models. We also find that
the host morphology and the orbital parameters also have an effect on the
determining the mass removal, but they are of secondary importance with respect
to satellite morphology. We conclude that satellite morphology has a very
strong effect on the efficiency of stellar stripping and should be taken into
account in modeling galaxy formation and evolution.Comment: 11 pages, 9 figures; accepted for publication in MNRA
Analytic smoothness effect of solutions for spatially homogeneous Landau equation
In this paper, we study the smoothness effect of Cauchy problem for the
spatially homogeneous Landau equation in the hard potential case and the
Maxwellian molecules case. We obtain the analytic smoothing effect for the
solutions under rather weak assumptions on the initial datum.Comment: 16 page
Synthesis and structures of O-anthrylmethyl-substituted hexahomotrioxacalix[3]arenes
O-Alkylation of 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix[3]arene (1Hā) with 9-chloromethylanthracene 5 was carried out under different reaction conditions. Variation of the number of anthrylmethyl group introduced at the phenolic rim of hexahomotrioxacalix[3]arene 1Hā was achieved through selective O-alkylation using stoichiometric amounts of 9-chloromethylanthracene 5 in acetone to afford the mono-O-alkylated product 2HāAn, the di-O-alkylated product 3HAnā and the tri-O-alkylated product partial-cone-4Anā, respectively. Interestingly, by using an acetone/benzene (1:1 v/v) mixed solvent system, the cone-4Anā was successfully synthesized. These results suggest that the solvent can also control the conformation of the O-alkylation products. The possible reaction routes of the cone-4Anā and partial-cone-4Anā are also discussed
Analysis of controlled auto-ignition /HCCI combustion in a direct injection gasoline engine with single and split fuel injections
A multi-cycle three-dimensional CFD engine simulation programme has been developed and applied to analyze the Controlled autoignition (CAI) combustion, also known as homogeneous charge compression ignition (HCCI), in a direct injection gasoline engine. CAI operation was achieved through the negative valve overlap method by means of a set of low lift camshafts. In the first part of the paper, the effect of single injection timing on combustion phasing and underlying physical and chemical processes involved was examined through a series of analytical studies using the multi-cycle 3D engine simulation programme. The analyses showed that early injection into the trapped burned gases of a lean-burn mixture during the negative valve overlap period had a large effect on combustion phasing, due to localized heat release and the production of chemically reactive species. As the injection was retarded to the intake stroke, the charge cooling effect tended to slow down the autoignition process. However, further retard of fuel injection to the compression stroke caused the earlier start of main combustion as fuel stratification was produced in the cylinder. In order to optimize the engine performance and engine-out emissions, double injection was investigated by injecting part of the fuel first in the negative valve overlap period and the rest of fuel during the intake or compression strokes. By varying the fueling of each injection, the best engine performance was obtained with the 50/50 fuel injection split ratio, while the lowest total NOx and soot emissions were seen with the optimal split injection ratio of 10/90
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