Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optimizing water permeability through the hourglass shape of aquaporins   The ubiquitous aquaporin channels are able to conduct water across cell
membranes, combining the seemingly antagonist functions of a very high
selectivity with a remarkable permeability. Whereas molecular details are
obvious keys to perform these tasks, the overall efficiency of transport in
such nanopores is also strongly limited by viscous dissipation arising at the
connection between the nanoconstriction and the nearby bulk reservoirs. In this
contribution, we focus on these so-called entrance effects and specifically
examine whether the characteristic hourglass shape of aquaporins may arise from
a geometrical optimum for such hydrodynamic dissipation. Using a combination of
finite-element calculations and analytical modeling, we show that conical
entrances with suitable opening angle can indeed provide a large increase of
the overall channel permeability. Moreover, the optimal opening angles that
maximize the permeability are found to compare well with the angles measured in
a large variety of aquaporins. This suggests that the hourglass shape of
aquaporins could be the result of a natural selection process toward optimal
hydrodynamic transport. Finally, in a biomimetic perspective, these results
provide guidelines to design artificial nanopores with optimal performances.

6
The categories of this paper are: astro-ph
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The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
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The categories of this paper are: eess
34
The categories of this paper are: chem-ph
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The categories of this paper are: patt-sol