Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamic nuclear polarisation of liquids at one microtesla using
  circularly polarised RF with application to millimetre resolution MRI   Magnetic resonance imaging in ultra-low fields is often limited by mediocre
signal-to-noise ratio hindering a higher resolution. Overhauser dynamic nuclear
polarisation (O-DNP) using nitroxide radicals has been an efficient solution
for enhancing the thermal nuclear polarisation. However, the concurrence of
positive and negative polarisation enhancements arises in ultra-low fields
resulting in a significantly reduced net enhancement, making O-DNP far less
attractive. Here, we address this issue by applying circularly polarised RF.
O-DNP with circularly polarised RF renders a considerably improved enhancement
factor of around 150,000 at 1.2 microtesla. A birdcage coil was adopted into a
ultra-low field MRI system to generate the circularly polarised RF field
homogeneously over a large volume. We acquired an MR image of a nitroxide
radical solution with an average in-plane resolution of 1 mm. De-noising
through compressive sensing further improved the image quality.

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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-th
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: eess
0
The categories of this paper are: hep-ph
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The categories of this paper are: q-alg
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The categories of this paper are: astro-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph