Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of anisotropic diffusion of light in compacted granular
  porous materials   It is known that compaction of granular matter can lead to anisotropic
mechanical properties. Recent work has confirmed the link to pore space
anisotropy, but the relation between compression, mechanical properties and
material microstructure remains poorly understood and new diagnostic tools are
needed. By studying the temporal and spatial characteristics of short optical
pulses diffusively transmitted through compacted granular materials, we show
that powder compaction can also give rise to strongly anisotropic diffusion of
light. Investigating technologically important materials such as
microcrystalline cellulose, lactose and calcium phosphate, we report increasing
optical anisotropy with compaction force and radial diffusion constants being
up to 1.7 times the longitudinal. This open new and attractive routes to
material characterization and investigation of compression-induced structural
anisotropy. In addition, by revealing inadequacy of isotropic diffusion models,
our observations also have important implications for quantitative spectroscopy
of powder compacts (e.g., pharmaceutical tablets).

18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph