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Figure 3
Radial power spectra of apoferritin in devitrified (a, b) and vitreous (c, d) water. Average radial signal intensities were calculated from 1600–2600 particles and the same number of background regions of equal size. The blue line shows the difference between the power spectra of particles (red) and background (black) for regions of the transform where the particle signal is above background. For particles in cubic ice this was the case to 0.250 Å−1 (a) or 0.255 Å−1 (b), and for particles in vitreous water to 0.244 Å−1 (c) or 0.255 Å−1 (d). In the regions beyond, background was stronger except for sporadic higher frequencies. Particle and background intensities at low spatial frequency extend to 1.9–4.6 × 105.

IUCrJ
Volume 8| Part 2| March 2021| Pages 186-194
ISSN: 2052-2525
https://doi.org/10.1107/S2052252520016243