Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution of structural properties of iron oxide nano particles during
  temperature treatment from 250{\deg}C - 900{\deg}C: X-ray diffraction and Fe
  K-shell pre-edge X-ray absorption study
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph