Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Water and Ion Transfer to Narrow Carbon Nanotubes: Roles of Exterior and
  Interior   Narrow carbon nanotubes (CNTs) desalinate water, mimicking water channels of
biological membranes, yet the physics behind selectivity, especially, the
effect of the membrane embedding CNTs on water and ion transfer, is still
unclear. Here, we report $ab$ $initio$ analysis of the energies involved in
transfer of water and K$^+$ and Cl$^-$ ions from solution to empty and
water-filled 0.68 nm CNTs, for different dielectric constants $\epsilon$ of the
surrounding matrix. The transfer energies computed for $1 \leq \epsilon <
\infty$ permit a transparent breakdown of the transfer energy to three main
contributions: binding to CNT, intra-CNT hydration, and dielectric polarization
of the matrix. The latter scales inversely with $\epsilon$ and is of the order
$10^2$/$\epsilon$ kJ/mol for both ions, which may change ion transfer from
favorable to unfavorable, depending on ion, $\epsilon$, and CNT diameter. This
may have broad implications for designing and tuning selectivity of
nanochannel-based devices.

5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin