The effect of B1 field inhomogeneity and the nonselective inversion profile on the kinetics of FAIR-based perfusion MRI

2005 ◽  
Vol 53 (6) ◽  
pp. 1355-1362 ◽  
Author(s):  
Janneke Schepers ◽  
Matthias J. P. van Osch ◽  
Lambertus W. Bartels ◽  
Sean N. Heukels ◽  
Max A. Viergever ◽  
...  
Keyword(s):  
Perfusion Mri ◽  
Field Inhomogeneity ◽  
B1 Field ◽  
Kinetics Of

Quantitative T1ρ imaging using phase cycling for B0 and B1 field inhomogeneity compensation

2011 ◽  
Vol 29 (5) ◽  
pp. 608-619 ◽  
Author(s):  
Weitian Chen ◽  
Atsushi Takahashi ◽  
Eric Han
Keyword(s):  
Field Inhomogeneity ◽  
Phase Cycling ◽  
B1 Field

scholarly journals Suppression of probe background signals via B1 field inhomogeneity

2011 ◽  
Vol 209 (2) ◽  
pp. 300-305 ◽  
Author(s):  
Jian Feng ◽  
Jeffrey A. Reimer
Keyword(s):  
Field Inhomogeneity ◽  
B1 Field

scholarly journals Transmit B1+ field inhomogeneity and T1estimation errors in breast DCE-MRI at 3 tesla

2013 ◽  
Vol 38 (2) ◽  
pp. 454-459 ◽  
Author(s):  
Kyunghyun Sung ◽  
Bruce L. Daniel ◽  
Brian A. Hargreaves
Keyword(s):  
3 Tesla ◽  
Field Inhomogeneity ◽  
Dce Mri ◽  
B1 Field

scholarly journals Using nutation-frequency-selective pulses to reduce radio-frequency field inhomogeneity in solid-state NMR

2020 ◽  
Author(s):  
Kathrin Aebischer ◽  
Nino Wili ◽  
Zdeněk Tošner ◽  
Matthias Ernst
Keyword(s):  
Solid State ◽  
Radio Frequency ◽  
Solid State Nmr ◽  
Sample Volume ◽  
Field Inhomogeneity ◽  
Spin Lock ◽  
Selective Pulses ◽  
Physical Volume ◽  
The Family ◽  
B1 Field

Abstract. Radio-frequency (rf) field inhomogeneity is a common problem in NMR which leads to non-ideal rotations of spins in parts of the sample. Often, a physical volume restriction of the sample is used to reduce the effects of rf-field inhomogeneity especially in solid-state NMR where spacers are inserted to reduce the sample volume to the centre of the coil. We show that band-selective pulses in the spin-lock frame can be used to apply B1-field selective inversions to spins that experience selected parts of the rf-field distribution. Any frequency band-selective pulse can be used for this purpose but we chose the family of I-BURP pulses (H. Geen, R. Freeman, Band-Selective Radiofrequency Pulses, J. Magn. Reson. 93 (1991) 93–141) for the measurements demonstrated here. As an example, we show that the implementation of such pulses improves homonuclear frequency-switched Lee-Goldburg decoupling in solid-state NMR.

scholarly journals Using nutation-frequency-selective pulses to reduce radio-frequency field inhomogeneity in solid-state NMR

2020 ◽  
Vol 1 (2) ◽  
pp. 187-195
Author(s):  
Kathrin Aebischer ◽  
Nino Wili ◽  
Zdeněk Tošner ◽  
Matthias Ernst
Keyword(s):  
Solid State ◽  
Radio Frequency ◽  
Solid State Nmr ◽  
Sample Volume ◽  
Field Inhomogeneity ◽  
Spin Lock ◽  
Selective Pulses ◽  
Physical Volume ◽  
The Family ◽  
B1 Field

Abstract. Radio-frequency (rf) field inhomogeneity is a common problem in NMR which leads to non-ideal rotations of spins in parts of the sample. Often, a physical volume restriction of the sample is used to reduce the effects of rf-field inhomogeneity, especially in solid-state NMR where spacers are inserted to reduce the sample volume to the centre of the coil. We show that band-selective pulses in the spin-lock frame can be used to apply B1-field selective inversions to spins that experience selected parts of the rf-field distribution. Any frequency band-selective pulse can be used for this purpose, but we chose the family of I-BURP pulses (Geen and Freeman, 1991) for the measurements demonstrated here. As an example, we show that the implementation of such pulses improves homonuclear frequency-switched Lee–Goldburg decoupling in solid-state NMR.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

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