Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Electrical and structural properties of MgB2 films prepared by
  sequential deposition of B and Mg on the NbN buffered Si(100) substrate
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
2
The categories of this paper are: math