9,321 research outputs found
Driving dynamic colloidal assembly using eccentric self-propelled colloids
Designing protocols to dynamically direct the self-assembly of colloidal
particles has become an important direction in soft matter physics because of
the promising applications in fabrication of dynamic responsive functional
materials. Here using computer simulations, we found that in the mixture of
passive colloids and eccentric self-propelled active particles, when the
eccentricity and self-propulsion of active particles are high enough, the
eccentric active particles can push passive colloids to form a large dense
dynamic cluster, and the system undergoes a novel dynamic demixing transition.
Our simulations show that the dynamic demixing occurs when the eccentric active
particles move much faster than the passive particles such that the dynamic
trajectories of different active particles can overlap with each other while
passive particles are depleted from the dynamic trajectories of active
particles. Our results suggest that this is in analogy to the entropy driven
demixing in colloid-polymer mixtures, in which polymer random coils can overlap
with each other while deplete the colloids. More interestingly, we find that by
fixing the passive colloid composition at certain value, with increasing the
density, the system undergoes an intriguing re-entrant mixing, and the demixing
only occurs within certain intermediate density range. This suggests a new way
of designing active matter to drive the self-assembly of passive colloids and
fabricate dynamic responsive materials.Comment: Accepted in Soft Matter. Supplementary information can found at
https://www.dropbox.com/sh/xb3u5iaoucc2ild/AABFUyqjXips7ewaie2rFbj_a?dl=
Distance, Growth Factor, and Dark Energy Constraints from Photometric Baryon Acoustic Oscillation and Weak Lensing Measurements
Baryon acoustic oscillations (BAOs) and weak lensing (WL) are complementary
probes of cosmology. We explore the distance and growth factor measurements
from photometric BAO and WL techniques and investigate the roles of the
distance and growth factor in constraining dark energy. We find for WL that the
growth factor has a great impact on dark energy constraints but is much less
powerful than the distance. Dark energy constraints from WL are concentrated in
considerably fewer distance eigenmodes than those from BAO, with the largest
contributions from modes that are sensitive to the absolute distance. Both
techniques have some well determined distance eigenmodes that are not very
sensitive to the dark energy equation of state parameters w_0 and w_a,
suggesting that they can accommodate additional parameters for dark energy and
for the control of systematic uncertainties. A joint analysis of BAO and WL is
far more powerful than either technique alone, and the resulting constraints on
the distance and growth factor will be useful for distinguishing dark energy
and modified gravity models. The Large Synoptic Survey Telescope (LSST) will
yield both WL and angular BAO over a sample of several billion galaxies. Joint
LSST BAO and WL can yield 0.5% level precision on ten comoving distances evenly
spaced in log(1+z) between redshift 0.3 and 3 with cosmic microwave background
priors from Planck. In addition, since the angular diameter distance, which
directly affects the observables, is linked to the comoving distance solely by
the curvature radius in the Friedmann-Robertson-Walker metric solution, LSST
can achieve a pure metric constraint of 0.017 on the mean curvature parameter
Omega_k of the universe simultaneously with the constraints on the comoving
distances.Comment: 15 pages, 9 figures, details and references added, ApJ accepte
catena-Poly[(diaquaÂcadmium)-μ-4,4′-[sulfonylÂbisÂ(1,4-phenylÂeneÂoxy)]ÂdiÂacetÂato-κ4 O,O′:O′′,O′′′]
In the title coordination polymer, [Cd(C16H12O8S)(H2O)2]n, the CdII ion is situated on a crystallographic twofold rotation axis, being coordinated by four O atoms from two bidentate 4,4′-[sulfonylÂbisÂ(1,4-phenylÂeneÂoxy)]diacetate (L) ligands and two water molÂecules in a highly distorted CdO6 octaÂhedral geometry. Each complete ligand L, which is also generated by twofold symmetry with the S atom lying on the rotation axis, bridges two CdII atoms to form a polymeric zigzag chain propagating in the [10-1] direction. O—H⋯O hydrogen bonds between the coordinated water molÂecules and carboxylÂate O atoms are involved in the packing
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