38,566 research outputs found
Zinc 2-((2-(benzoimidazol-2-yl)quinolin-8-ylimino)methyl)phenolates : synthesis, characterization and photoluminescence behavior
A series of 2-(2-(1H-benzoimidazol-2-yl)quinolin-8-yliminomethyl)phenol derivatives and their zinc complexes (C1 – C5) were synthesized and fully characterized. The molecular structure of the representative complex C2 was determined by single crystal X-ray diffraction, which revealed that the zinc was five-coordinated with the tetra-dentate ligand and a methanol bound to the metal afford a distorted square-pyramidal geometry. The UV-Vis absorption and fluorescence spectra of the organic compounds and their zinc complexes were measured and investigated in various solvents such as methanol, THF, dichloromethane, and toluene; significant influences by solvents were observed on their luminescent properties; red-shifts for the zinc complexes were clearly observed in comparisons to the free organic compounds
Analysis of Large Urn Models with Local Mean-Field Interactions
The stochastic models investigated in this paper describe the evolution of a
set of identical balls scattered into urns connected by an underlying
symmetrical graph with constant degree . After some random amount of time
{\em all the balls} of any urn are redistributed locally, among the urns
of its neighborhood. The allocation of balls is done at random according to a
set of weights which depend on the state of the system. The main original
features of this context is that the cardinality of the range of
interaction is not necessarily linear with respect to as in a classical
mean-field context and, also, that the number of simultaneous jumps of the
process is not bounded due to the redistribution of all balls of an urn at the
same time. The approach relies on the analysis of the evolution of the local
empirical distributions associated to the state of urns located in the
neighborhood of a given urn. Under convenient conditions, by taking an
appropriate Wasserstein distance and by establishing several technical
estimates for local empirical distributions, we are able to prove mean-field
convergence results.
When the load per node goes to infinity, a convergence result for the
invariant distribution of the associated McKean-Vlasov process is obtained for
several allocation policies. For the class of power of choices policies, we
show that the associated invariant measure has an asymptotic finite support
property under this regime. This result differs somewhat from the classical
double exponential decay property usually encountered in the literature for
power of choices policies
Topological invariants for holographic semimetals
We study the behavior of fermion spectral functions for the holographic
topological Weyl and nodal line semimetals. We calculate the topological
invariants from the Green functions of both holographic semimetals using the
topological Hamiltonian method, which calculates topological invariants of
strongly interacting systems from an effective Hamiltonian system with the same
topological structure. Nontrivial topological invariants for both systems have
been obtained and the presence of nontrivial topological invariants further
supports the topological nature of the holographic semimetals.Comment: 39 pages, 11 figures, 1 table; v2: match published versio
Topological nodal line semimetals in holography
We show a holographic model of a strongly coupled topological nodal line
semimetal (NLSM) and find that the NLSM phase could go through a quantum phase
transition to a topologically trivial state. The dual fermion spectral function
shows that there are multiple Fermi surfaces each of which is a closed nodal
loop in the NLSM phase. The topological structure in the bulk is induced by the
IR interplay between the dual mass operator and the operator that deforms the
topology of the Fermi surface. We propose a practical framework for building
various strongly coupled topological semimetals in holography, which indicates
that at strong coupling topologically nontrivial semimetal states generally
exist.Comment: 21 pages, 5 figures; v2: match published versio
Production of antimatter Li nuclei in central Au+Au collisions at GeV
Combining the covariant coalescence model and a blast-wave-like analytical
parametrization for (anti-)nucleon phase-space freezeout configuration, we
explore light (anti-)nucleus production in central Au+Au collisions at
GeV. Using the nucleon freezeout configuration (denoted
by FO1) determined from the measured spectra of protons (p), deutrons (d) and
He, we find the predicted yield of He is significantly smaller than
the experimental data. We show this disagreement can be removed by using a
nucleon freezeout configuration (denoted by FO2) in which the nucleons are
assumed to freeze out earlier than those in FO1 to effectively consider the
effect of large binding energy value of He. Assuming the binding energy
effect also exists for the production of ,
, and due to
their similar binding energy values as He, we find the yields of these
heavier (anti-)nuclei can be enhanced by a factor of about one order, implying
that although the stable (anti-)Li nucleus is unlikely to be observed, the
unstable (anti-)Li nucleus could be produced in observable abundance in
Au+Au collisions at GeV where it may be identified
through the p- (-)
invariant mass spectrum. The future experimental measurement on
(anti-) would be very useful to understand the production
mechanism of heavier antimatter.Comment: 8 pages, 2 figures, 3 tables. Typos fixed and one ref added. Accepted
version to appear in PL
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