Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Self-heating effects of the surface oxidized FeCo nanoparticles colloid
  under alternating magnetic field   To evaluate the self-heating effects of FeCo magnetic nanoparticles, the
surface oxidized FeCo nanoparticles were synthesized by co-precipitation method
with the reduction reaction without any post treatments. As-synthesized FeCo
nanoparticles exhibited the mean diameter of about 39 nm with the oxidized
shell thickness of about 4-5 nm. The saturation magnetization and coercivity
were obtained 172 emu/g and 268 Oe at 300 K, respectively. The heat elevation
of the FeCo magnetic colloid was measured under alternating magnetic fields of
76, 102, and 127 Oe with selectable frequencies of 190, 250 and 355 kHz. The
heat temperature increased up to about 45 oC from initial temperature of 24 oC
under 127 Oe and 355 kHz, which the specific absorption exhibited about 35.7
W/g.

23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin