Determination of the Spectral Density FunctionJ1(ω)in SolidHe3from Nuclear-Relaxation Measurements

1966 ◽  
Vol 146 (1) ◽  
pp. 244-253 ◽  
Author(s):  
Robert C. Richardson ◽  
André Landesman ◽  
Earle Hunt ◽  
Horst Meyer
Keyword(s):  
Spectral Density ◽  
Nuclear Relaxation ◽  
Relaxation Measurements

scholarly journals Cross-correlated relaxation measurements under adiabatic sweeps: determination of local order in proteins

2015 ◽  
Vol 63 (4) ◽  
pp. 353-365 ◽  
Author(s):  
Pavel Kadeřávek ◽  
Sarina Grutsch ◽  
Nicola Salvi ◽  
Martin Tollinger ◽  
Lukáš Žídek ◽  
...  
Keyword(s):  
Local Order ◽  
Relaxation Measurements

A Selective Determination of the Proton Nuclear Relaxation Times of the Alkaloid Vindoline: An Extension via Fourier Transform Measurements

1974 ◽  
Vol 52 (5) ◽  
pp. 829-832 ◽  
Author(s):  
L. D. Hall ◽  
Caroline M. Preston
Keyword(s):  
Fourier Transform ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Nuclear Relaxation ◽  
Transform Method ◽  
Fourier Transform Method ◽  
Selective Determination ◽  
Spin Lattice

A Fourier Transform method has been used to measure the spin–lattice relaxation times of essentially all the protons of the alkaloid, vindoline. It is shown that even for a molecule of this size substantial and potentially useful differences exist in the experimental relaxation times which reflect the degree of crowding of each proton by other protons.

scholarly journals Optimum Resolution Bandwidth for Spectral Analysis of Stationary Random Vibration Data

1993 ◽  
Vol 1 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Allan G. Piersol
Keyword(s):  
Spectral Analysis ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Random Vibration ◽  
Damping Ratio ◽  
Frequency Resolution ◽  
Power Spectral ◽  
Averaging Time ◽  
Resolution Bandwidth

This article presents a methodology for selecting the frequency resolution bandwidth for the spectral analysis of stationary random vibration signals in an optimum manner. Specifically, the resolution bandwidth that will produce power spectral density estimates with a minimum mean square error is determined for any given measurement duration (averaging time), and methods of approximating the optimum bandwidth using practical spectral analysis procedures are detailed. The determination of the optimum resolution bandwidth requires an estimate for the damping ratio of the vibrating structure that produced the measured vibration signal and the analysis averaging time. It is shown that the optimum resolution bandwidth varies approximately with the 0.8 power of the damping ratio and the bandwidth center frequency, and the −0.2 power of the averaging time. Also, any resolution bandwidth within ±50% of the optimum bandwidth will produce power spectral density (PSD) estimates with an error that is no more than 25% above the minimum achievable error. If a damping ratio of about 5% for structural resonances is assumed, a constant percentage resolution bandwidth of 1/12 octave, but no less than 2.5 Hz, will provide a near optimum PSD analysis for an averaging time of 2 seconds over the frequency range from 20 to 2000 Hz. A simple scaling formula allows the determination of appropriate bandwidths for other damping ratios and averaging times.

scholarly journals Properties of the cupric sites in bovine superoxide dismutase studied by nuclear-magnetic-relaxation measurements

1979 ◽  
Vol 177 (1) ◽  
pp. 303-309 ◽  
Author(s):  
N Boden ◽  
M C Holmes ◽  
P F Knowles
Keyword(s):  
Superoxide Dismutase ◽  
Water Molecule ◽  
Magnetic Relaxation ◽  
Nuclear Relaxation ◽  
Histidine Residue ◽  
Relaxation Rates ◽  
Cyanide Concentration ◽  
Relaxation Measurements ◽  
Bovine Erythrocytes ◽  
Frequency Temperature

Proton nuclear-relaxation rates have been measured as a function of frequency, temperature, pH and cyanide concentration in aqueous solutions of superoxide dismutase from bovine erythrocytes. The results show that, whereas for pH less than or equal to 9 only one water molecule is bound to each Cu2+ ion, at higher pH a second co-ordination site for OH- becomes available; it is proposed that this involves cleavage of the bond between Cu2+ and the histidine residue that bridges to Zn2+.

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