Suppression of strong coupling artefacts in J-spectra

Thrippleton, Michael J.; Edden, Richard A.E.; Keeler, James

doi:10.1016/j.jmr.2005.01.012

Cited by 102 publications

(96 citation statements)

References 20 publications

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“…Strong coupling artefacts were suppressed by phase cycling. 32 Before Fourier transformation, 2D J-RES spectra were multiplied by a combined sine-bell/exponential window function in the direct dimension and by a sine bell function in the incremented dimension. 33 Skyline projections were calculated and spectra were aligned.…”

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confidence: 99%

Metabolomic Analysis of Diapausing and Noni-diapausing Larvae of the European Corn Borer Ostrinia nubilalis (Hbn.) (Lepidoptera: Crambidae)

Purać

Kojić

Popović

et al. 2015

ACSi

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In this study, an 1 H-NMR -based metabolomic approach was used to investigate the biochemical mechanisms of diapause and cold hardiness in diapausing larvae of the European corn borer Ostrinia nubilalis. Metabolomic patterns in polar hemolymph extracts from non-diapausing and diapausing larvae of O. nubilalis were compared. Analysis indicated 13 metabolites: 7 amino acids, glycerol, acetate, citrate, succinate, lactate and putrescine. Results show that diapausing larvae display different metabolomic patterns compared to active non-diapausing larvae, with predominant metabolites identified as glycerol, proline and alanine. In specific diapausing larvae initially kept at 5 °C then gradually chilled to -3 °C and -16 °C, alanine , glycerol and acetate were predominant metabolites. 1 H-NMR spectroscopy provides new insight into the metabolomic patterns associated with cold resistance and diapause in O. nubilalis larvae, suggesting distinct metabolomes function in actively developing and diapausing larvae.

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confidence: 99%

Metabolomic Analysis of Diapausing and Noni-diapausing Larvae of the European Corn Borer Ostrinia nubilalis (Hbn.) (Lepidoptera: Crambidae)

Purać

Kojić

Popović

et al. 2015

ACSi

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“…The extent of the signal loss can vary considerably depending on the field strength, the used coil and the sequence parameters. One example is the doublet at 1.33 ppm of lactate, which can completely disappear at 3 T for TE 144 ms. Strategies to prevent or alleviate the signal loss due to anomalous J-modulation present both advantages and disadvantages [12,49,51].…”

Section: Chemical Shift Misregistration and J-modulation Artifactsmentioning

confidence: 99%

“…Several editing sequences cannot be applied with 1.5-T scanners since they need higher SNR and sufficient spectral resolution. Examples of unresolved metabolites due to the J-coupling phenomenon are the Glx-components glutamate, glutamine and GABA, which cannot be easily differentiated from each other at 1.5 T and therefore have been frequently treated as a metabolite group [49,51,[56][57][58].…”

Section: Spectral Editingmentioning

confidence: 99%

Proton MR spectroscopy of the brain at 3 T: an update

et al. 2007

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“…(8), since the frequency of the dips is smaller than J and the amplitude of the modulations is larger than expected. The origin of this discrepancy could be due to strong coupling artefacts [36,37]. The (poor) fits led to R 2 = 0.42 ± 0.7 s À1 for the PFCT echoes and R 2 = 0.39 ± 0.3 s À1 for the MQF sequence.…”

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confidence: 98%

Determination of transverse relaxation rates in systems with scalar-coupled spins: The role of antiphase coherences

Segawa

Bodenhausen

2013

Journal of Magnetic Resonance

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a b s t r a c tHomogeneous line-widths that arise from transverse relaxation tend to be masked by B 0 field inhomogeneity and by multiplets due to homonuclear J-couplings. Besides well-known spin-locking sequences that lead to signals that decay with a rate R 1q without any modulations, alternative experiments allow one to determine the transverse relaxation rates R 2 in systems with scalar-coupled spins. We evaluate three recent strategies by experiment and simulation: (i) moderate-amplitude SITCOM-CPMG sequences (Dittmer and Bodenhausen, 2006 [2]), (ii) multiple-quantum filtered (MQF) sequences (Barrère et al., 2011 [4]) and (iii) PROJECT sequences (Aguilar et al., 2012 [5]). Experiments where the J-evolution is suppressed by spin-locking measure the pure relaxation rate R 2 (I x ) of an in-phase component. Experiments based on Jrefocusing yield a mixture of in-phase rates R 2 (I x ) and antiphase rates R 2 (2I y S z ), where the latter are usually faster than the former. Moderate-amplitude SITCOM-CPMG and PROJECT methods can be applied to systems with many coupled spins, but applications of MQF sequences are limited to two-spin systems since modulations in larger systems can only partly be suppressed.Ó 2013 Elsevier Inc. All rights reserved.When speaking of ''decoupling'', most NMR practitioners primarily think of collapsing multiplets stemming from J-couplings. In this article however, we shall focus on decoupling in time domain rather than in frequency domain. In other words, we will study methods that can 'smooth out' decays that are normally modulated by J-couplings. Indeed, the effects of couplings can be cancelled either in frequency or in time domain. In a heteronuclear system, e.g., comprising a proton coupled to a carbon-13 nucleus, a simple broadband radiofrequency (rf) irradiation on one of the two nuclei is sufficient to achieve effective decoupling. This becomes challenging in the presence of homonuclear interactions. In such cases, the Larmor frequencies of the two nuclei can be very close and broadband rf irradiation might perturb all spins, instead of affecting only one coupling partner. The same ''homonuclear challenge'' appears when attempting to measure the transverse relaxation rate R 2 = 1/T 2 of such a spin system. If a spin echo is applied to a system of coupled protons, the echo envelope does not decay exponentially, but is modulated by homonuclear J-couplings. The first observation of such 'echo modulations' was made by Erwin Hahn while studying protons in ethanol shortly after the original discovery of spin echoes back in 1950 [1].The spin echo is approaching an age where retirement is mandatory for many. Yet homonuclear decoupling and measurements of transverse relaxation rates in coupled spin systems remain an active field of research in NMR spectroscopy. In the last few years, several approaches were presented to tackle this challenge [2][3][4][5]. We recently reviewed the phenomenon of echo modulations [6,7]. In this paper, we would like to compare different pulse sequences and e...

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Suppression of strong coupling artefacts in J-spectra

Cited by 102 publications

References 20 publications

Metabolomic Analysis of Diapausing and Noni-diapausing Larvae of the European Corn Borer Ostrinia nubilalis (Hbn.) (Lepidoptera: Crambidae)

Metabolomic Analysis of Diapausing and Noni-diapausing Larvae of the European Corn Borer Ostrinia nubilalis (Hbn.) (Lepidoptera: Crambidae)

Proton MR spectroscopy of the brain at 3 T: an update

Determination of transverse relaxation rates in systems with scalar-coupled spins: The role of antiphase coherences

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