Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Epitaxial refractory-metal buer layers with a chemical gradient for
  adjustable lattice parameter and controlled chemical interface   We have developed and characterized the structure and composition of
nanometers-thick solid-solution epitaxial layers of (V,Nb) on sapphire (1120),
displaying a continuous lateral gradient of composition from one to another
pure element. Further covered with an ultrathin pseudomorphic layer of W, these
provide a template for the fast combinatorial investigation of any growth or
physical property depending of strain.

28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org