Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Intelligent smartphone-based portable network diagnostics for water
  security Case Study realtime pH mapping of tap water
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat