Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The desalting/salting pathway: a route to form metastable aggre-gates
  with tuneable morphologies and lifetimes   We investigate the formation/re-dissociation mechanisms of hybrid complexes
made from negatively charged PAA2k coated {\gamma}-Fe2O3 nanoparticles (NP) and
positively charged polycations (PDADMAC) in aqueous solution in the regime of
very high ionic strength (I). When the building blocks are mixed at large ionic
strength (1M NH4Cl), the electrostatic interaction is screened and complexation
does not occur. If the ionic strength is then lowered down to a targeted ionic
strength Itarget, there is a critical threshold Ic = 0.62 M at which
complexation occurs, that is independent on the charge ratio Z and the pathway
used to reduce salinity (drop-by-drop mixing or fast mixing). If salt is added
back up to 1M, the transition is not reversible and persistent
out-of-equilibrium aggregates are formed. The lifetimes of such aggregates
depends on Itarget: the closer Itarget to Ic is, the more difficult it is to
dissolve the aggregates. Such peculiar behavior is driven by the inner
structure of the complexes that are formed after desalting. When Itarget is far
below Ic, strong electrostatic interactions induce the formation of dense,
compact and frozen aggregates. Such aggregates can only poorly reorganize
further on with time, which makes their dissolution upon resalting almost
reversible. Conversely, when Itarget is close to Ic more open aggregates are
formed due to weaker electrostatic interactions upon desalting. System can thus
rearrange with time to lower its free energy and reach more stable
out-of-equilibrium states which are very difficult to dissociate back upon
resalting, even at very high ionic strength.

15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio