Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Synthesis of metallic nanoparticles for heterogeneous catalysis:
  Application to the Direct Borohydride Fuel Cell
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn