Preparing samples for DNP experiments sometimes involves using sedimented solutes. This is a nice overview of the technique and how it is beneficial for DNP-NMR spectroscopy.
Ravera, E., The bigger they are, the harder they fall: A topical review on sedimented solutes for solid-state NMR. Concepts in Magnetic Resonance Part A, 2014. 43(6): p. 209-227.
http://dx.doi.org/10.1002/cmr.a.21318
Sample preparation for solid-state NMR of soluble proteins is all but a trivial accomplishment and often represents the factor that determines the success of the experiments, despite the dramatic methodological and technological improvements in the field of SSNMR. Several different sample preparation have been proposed and applied over the years, with varied results. Among those methods we have proposed the use of sedimentation for obtaining samples with high sensitivity and resolution. This review aims at covering the applications of NMR to sedimented solutes from its first description to the latest developments with implications in the field of DNP. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part A 43A: 209–227, 2015.