title: Genetic algorithm optimized triply compensated pulses in NMR spectroscopy.
abstract: Sensitivity and resolution in NMR experiments are affected by magnetic field inhomogeneities (of both external and RF), errors in pulse calibration, and offset effects due to finite length of RF pulses. To remedy these problems, built-in compensation mechanisms for these experimental imperfections are often necessary. Here, we propose a new family of phase-modulated constant-amplitude broadband pulses with high compensation for RF inhomogeneity and heteronuclear coupling evolution. These pulses were optimized using a genetic algorithm (GA), which consists in a global optimization method inspired by Nature's evolutionary processes. The newly designed π and π/2 pulses belong to the 'type A' (or general rotors) symmetric composite pulses. These GA-optimized pulses are relatively short compared to other general rotors and can be used for excitation and inversion, as well as refocusing pulses in spin-echo experiments. The performance of the GA-optimized pulses was assessed in Magic Angle Spinning (MAS) solid-state NMR experiments using a crystalline U-(13)C, (15)N NAVL peptide as well as U-(13)C, (15)N microcrystalline ubiquitin. GA optimization of NMR pulse sequences opens a window for improving current experiments and designing new robust pulse sequences.
authors.affiliation: Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States.
authors.forename: V S
authors.initials: VS
authors.lastname: Manu
authors.affiliation: Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States. Electronic address: vegli001@umn.edu.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Veglia
mesh_terms: D000465:Algorithms; D005075:Biological Evolution; D004574:Electromagnetic Fields; D005823:Genetics / Q000706:statistics & numerical data; D009682:Magnetic Resonance Spectroscopy / Q000706:statistics & numerical data*; D008869:Microtubule-Associated Proteins / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D025801:Ubiquitin / Q000737:chemistry
chemical_list: D008869:Microtubule-Associated Proteins; C503386:Nav1 protein, mouse; D010455:Peptides; D025801:Ubiquitin
keywords: Composite pulses; Genetic algorithm; Pulse imperfections; RF inhomogeneity; Resonance offset; Triply compensated pulses; zz interactions