Spin-lattice relaxation of carbon-13 in the rotating frame

Ohuchi, Muneki; Fujito, Teruaki; Imanari, Mamoru

doi:10.1016/0022-2364(79)90064-7

Cited by 15 publications

(8 citation statements)

References 27 publications

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“…One category comprises the CAMELSPIN (13) or ROESY (for rotating-frame Overhauser enhancement spectroscopy) (14), the rotating frame counterparts of the homonuclear NOE spectroscopy. The other category is T 1 measurements for heteronuclei with spin 1 2 (15)(16)(17)(18) and with higher spin quantum number (6, 19 -21). This technique allows one to sample spectral densities at frequencies of the order of RF field strength, thus making slow processes effective.…”

Section: Introductionmentioning

confidence: 99%

NMR Relaxation in Multipolar AX Systems under Spin Locking Conditions

Kaikkonen

Kowalewski

1999

Journal of Magnetic Resonance

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A relaxation matrix has been calculated for a multipolar AX spin system under the on-resonance spin-locking condition. Auto- and cross-correlation terms between dipolar, quadrupolar, and CSA interactions are considered. It is shown that the spin-lock leads to many relaxation pathways being blocked, resulting in a considerably simplified relaxation network. The presence of spectral densities at zero frequency, associated with locked nuclei, allows efficient relaxation also in the absence of fast molecular motions.

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Section: Introductionmentioning

confidence: 99%

NMR Relaxation in Multipolar AX Systems under Spin Locking Conditions

Kaikkonen

Kowalewski

1999

Journal of Magnetic Resonance

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“…To avoid complications from the decoupling source during the locking time, the proton decoupler was turned on only during FID collection time. 19 The center of the spectrum was carefully set to be less than 5 Hz away from the main peak to avoid any error caused by offresonance conditions. All T1F data were collected at 75 MHz 13 C Larmor frequency.…”

Section: Methodsmentioning

confidence: 99%

“…The actual power used was equivalent to the magnetic field for 2 kHz 13 C Larmor frequency. To avoid complications from the decoupling source during the locking time, the proton decoupler was turned on only during FID collection time . The center of the spectrum was carefully set to be less than 5 Hz away from the main peak to avoid any error caused by off-resonance conditions.…”

Section: Methodsmentioning

confidence: 99%

“…NMR methods provide several advantages over other experimental methods. First, a variety of nuclei can be utilized; 1 H, 13 C, 31 P, and 19 F are often found in polymer systems. Second, sensitivity toward different chemical structures allows the investigation of dynamics for chemically distinctive sites in homopolymers or individual components in a complex system such as a polymer blend.…”

Section: Introductionmentioning

confidence: 99%

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Entanglement Effects in Polyethylene Melts: ¹³C NMR Relaxation Experiments

Qiu

Ediger

2002

Macromolecules

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13 C NMR T1, NOE, and T1F were measured for two entangled polyethylene melts (M ) 16K and 37K) at 5 and 75 MHz 13 C Larmor frequencies from the melting point up to 530 K. Two models for entanglement dynamics are tested against the experimental data. This comparison shows that entanglements not only stretch out those relaxation times longer than the entanglement time τe but also have a spatial effect in restricting the motion of entangled points on the time scale of τe. For polyethylene, the amplitude of residual orientation on the time scale of τe is lower than the theoretical prediction for a Gaussian chain of the entanglement length with both ends fixed. The opposite conclusion was drawn from recent double quantum NMR experiments on polybutadiene. The magnetization decay curve for the T1F experiment is nonexponential, indicating that the loss of orientation on long time scales depends on position along the chain backbone.

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“…In particular, the component of the magnetization vector initially transverse to B eff will remain transverse to B eff , and the relaxation of the magnetization during that time is dominated by T 2ρ (24). Analytical expressions for T 1ρ and T 2ρ relaxation times have been worked out for a few cases (49,50). In liquid samples dominated by fast dipolar interactions, T 1 ρ → T 2 and

T_{2 ρ}^{- 1} \to (1 / 2) {(T_{1}^{- 1} + T_{2}^{- 1})}^{- 1}

(22,23,50).…”

Section: Theorymentioning

confidence: 99%

Combined off‐resonance imaging and T2 relaxation in the rotating frame for positive contrast MR imaging of infection in a murine burn model

Andronesi

Mintzopoulos

Psychogios

et al. 2010

Magnetic Resonance Imaging

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Purpose: To develop novel magnetic resonance (MR) imaging methods to monitor accumulation of macrophages in inflammation and infection. Positive-contrast MR imaging provides an alternative to negative-contrast MRI, exploiting the chemical shift induced by ultra-small superparamagnetic iron-oxide (USPIO) nanoparticles to nearby water molecules. We introduce a novel combination of off-resonance (ORI) positive-contrast MRI and T 2r relaxation in the rotating frame (ORI-T 2r ) for positive-contrast MR imaging of USPIO.Materials and Methods: We tested ORI-T 2r in phantoms and imaged in vivo the accumulation of USPIO-labeled macrophages at the infection site in a mouse model of burn trauma and infection with Pseudomonas aeruginosa (PA). PA infection is clinically important. The USPIO nanoparticles were injected directly in the animals in solution, and macrophage labeling occurred in vivo in the animal model. Results:We observed a significant difference between ORI-T 2r and ORI, which leads us to suggest that ORI-T 2r is more sensitive in detecting USPIO signal. To this end, the ORI-T 2r positive contrast method may prove to be of higher utility in future research. Conclusion:Our results may have direct implications in the longitudinal monitoring of infection, and open perspectives for testing novel anti-infective compounds.

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Spin-lattice relaxation of carbon-13 in the rotating frame

Cited by 15 publications

References 27 publications

NMR Relaxation in Multipolar AX Systems under Spin Locking Conditions

NMR Relaxation in Multipolar AX Systems under Spin Locking Conditions

Entanglement Effects in Polyethylene Melts: ¹³C NMR Relaxation Experiments

Combined off‐resonance imaging and T2 relaxation in the rotating frame for positive contrast MR imaging of infection in a murine burn model

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Spin-lattice relaxation of carbon-13 in the rotating frame

Cited by 15 publications

References 27 publications

NMR Relaxation in Multipolar AX Systems under Spin Locking Conditions

NMR Relaxation in Multipolar AX Systems under Spin Locking Conditions

Entanglement Effects in Polyethylene Melts: 13C NMR Relaxation Experiments

Combined off‐resonance imaging and T2 relaxation in the rotating frame for positive contrast MR imaging of infection in a murine burn model

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Entanglement Effects in Polyethylene Melts: ¹³C NMR Relaxation Experiments