NMR relaxation rate constants are powerful probes of the functional dynamics of biological macromolecules, such as proteins and nucleic acids. However, variations in choice of models used to analyze relaxation data obscure variations due to critical biological or chemical effects. Bootstrap aggregation, a recently developed statistical method, circumvents the model selection problem and enables more consistent and insightful interpretation of NMR relaxation data.

Shaped radiofrequency pulses are widely used in nuclear magnetic resonance (NMR) spectroscopy for selective excitation or inversion of magnetization. Efficient, accurate methods for calculating the performance of pulses enable the understanding of existing pulses and help to optimize new pulses. A new approach for approximating the effects of shaped pulses is introduced and applied to some popular shaped pulses as examples. This approach will also be useful in other areas of NMR spectroscopy.

We studied spin dynamics in nuclear spin systems at low magnetic fields, where strong coupling among nuclear spins of the same kind, here ¹³C, is expected. Such conditions are known to be favorable for coherent polarization transfer. However, to our surprise, interactions with other nuclei, i.e., protons, lead to a breakdown of the strong coupling conditions. By using a two-field nuclear magnetic resonance approach, we can manipulate low field-spin dynamics and reintroduce strong coupling.