Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Omnidirectional transport and navigation of Janus particles through a
  nematic liquid crystal film   We create controllable active particles in the form of metal-dielectric Janus
colloids which acquire motility through a nematic liquid crystal film by
transducing the energy of an imposed perpendicular AC electric field. We
achieve complete command over trajectories by varying field amplitude and
frequency, piloting the colloids at will in the plane spanned by the axes of
the particle and the nematic. The underlying mechanism exploits the sensitivity
of electro-osmotic flow to the asymmetries of the particle surface and the
liquid-crystal defect structure. We present a calculation of the dipolar force
density produced by the interplay of the electric field with director anchoring
and the contrasting electrostatic boundary conditions on the two hemispheres,
that accounts for the dielectric-forward (metal-forward) motion of the colloids
due to induced puller (pusher) force dipoles. These findings open unexplored
directions for the use of colloids and liquid crystals in controlled transport,
assembly and collective dynamics.

26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics