Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Tunable Assembly of Gold Nanorods in Polymer Solutions to Generate
  Controlled Nanostructured Materials   Gold nanorods grafted with short chain polymers are assembled into controlled
open structures using polymer-induced depletion interactions and structurally
characterized using small angle x-ray scattering. When the nanorod diameter is
smaller than the radius of gyration of the depletant polymer, the depletion
interaction depends solely on the correlation length of the polymer solution
and not directly on the polymer molecular weight. As the polymer concentration
increases, the stronger depletion interactions increasingly compress the
grafted chains and push the gold nanorods closer together. By contrast, other
structural characteristics such as the number of nearest neighbors and fractal
dimension exhibit a non-monotonic dependence on polymer concentration. These
parameters are maximal at intermediate concentrations, which are attributed to
a crossover from reaction-limited to diffusion-limited aggregation. The control
over structural properties of anisotropic nanoscale building blocks
demonstrated here will be beneficial to designing and producing materials
\emph{in situ} with specific direction-dependent nanoscale properties and
provides a crucial route for advances in additive manufacturing.

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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
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
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: solv-int
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The categories of this paper are: eess