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Journal of Magnetic Resonance

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https://www.readbyqxmd.com/read/29227914/design-and-use-of-a-folded-four-ring-double-tuned-birdcage-coil-for-rat-brain-sodium-imaging-at-9-4%C3%A2-t
#1
YongHyun Ha, Chang-Hoon Choi, Wieland A Worthoff, Aliaksandra Shymanskaya, Michael Schöneck, Antje Willuweit, Jörg Felder, N Jon Shah
A folded four-ring quadrature birdcage coil was designed and constructed with a double-tune configuration of an outer high-pass coil for 1H (400 MHz) and inner low-pass coil for 23Na (105.72 MHz at 9.4 T). The coil was evaluated on the bench and in the scanner, comparing its performance with that of single-tuned coils and a large four-ring coil. All coils were tuned and matched and the isolation between two quadrature ports was found to be better than -13.7 dB for 1H and -27 dB for 23Na. Signal-to-noise ratios (SNRs) were calculated and 23Na flip angle maps were acquired...
December 6, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29197695/probing-numerical-laplace-inversion-methods-for-two-and-three-site-molecular-exchange-between-interconnected-pore-structures
#2
Emilia V Silletta, María B Franzoni, Gustavo A Monti, Rodolfo H Acosta
Two-dimension (2D) Nuclear Magnetic Resonance relaxometry experiments are a powerful tool extensively used to probe the interaction among different pore structures, mostly in inorganic systems. The analysis of the collected experimental data generally consists of a 2D numerical inversion of time-domain data where T2-T2 maps are generated. Through the years, different algorithms for the numerical inversion have been proposed. In this paper, two different algorithms for numerical inversion are tested and compared under different conditions of exchange dynamics; the method based on Butler-Reeds-Dawson (BRD) algorithm and the fast-iterative shrinkage-thresholding algorithm (FISTA) method...
November 30, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29223566/progress-in-proton-detected-solid-state-nmr-ssnmr-super-fast-2d-ssnmr-collection-for-nano-mole-scale-proteins
#3
Yoshitaka Ishii, Ayesha Wickramasinghe, Isamu Matsuda, Yuki Endo, Yuji Ishii, Yusuke Nishiyama, Takahiro Nemoto, Takayuki Kamihara
Proton-detected solid-state NMR (SSNMR) spectroscopy has attracted much attention due to its excellent sensitivity and effectiveness in the analysis of trace amounts of amyloid proteins and other important biological systems. In this perspective article, we present the recent sensitivity limit of 1H-detected SSNMR using "ultra-fast" magic-angle spinning (MAS) at a spinning rate (νR) of 80-100 kHz. It was demonstrated that the high sensitivity of 1H-detected SSNMR at νR of 100 kHz and fast recycling using the paramagnetic-assisted condensed data collection (PACC) approach permitted "super-fast" collection of 1H-detected 2D protein SSNMR...
November 28, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29197694/experimental-investigation-of-a-metasurface-resonator-for-in-vivo-imaging-at-1-5%C3%A2-t
#4
Alena V Shchelokova, Alexey P Slobozhanyuk, Paul de Bruin, Irena Zivkovic, Efthymios Kallos, Pavel A Belov, Andrew Webb
In this work, we experimentally demonstrate an increase in the local transmit efficiency of a 1.5 T MRI scanner by using a metasurface formed by an array of brass wires embedded in a high permittivity low loss medium. Placement of such a structure inside the scanner results in strong coupling of the radiofrequency field produced by the body coil with the lowest frequency electromagnetic eigenmode of the metasurface. This leads to spatial redistribution of the near fields with enhancement of the local magnetic field and an increase in the transmit efficiency per square root maximum specific absorption rate in the region-of-interest...
November 22, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29223565/compressively-sampled-mr-image-reconstruction-using-generalized-thresholding-iterative-algorithm
#5
Sana Elahi, Muhammad Kaleem, Hammad Omer
Compressed sensing (CS) is an emerging area of interest in Magnetic Resonance Imaging (MRI). CS is used for the reconstruction of the images from a very limited number of samples in k-space. This significantly reduces the MRI data acquisition time. One important requirement for signal recovery in CS is the use of an appropriate non-linear reconstruction algorithm. It is a challenging task to choose a reconstruction algorithm that would accurately reconstruct the MR images from the under-sampled k-space data...
November 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29190516/57fe-internal-field-nuclear-magnetic-resonance-and-m%C3%A3-ssbauer-spectroscopy-study-of-li-zn-ferrites
#6
A V Anupama, M Manjunatha, V Rathod, V M Jali, R Damle, K P Ramesh, B Sahoo
We report the internal field nuclear magnetic resonance (IFNMR) and Mössbauer spectroscopy study of Li-Zn ferrites at RT. The results were supported by the IFNMR data measured at 77 K. As Zn concentration increases the IFNMR echo amplitude decreases and below certain Zn concentration no signal was detected. At RT the echo amplitude vanishes at a lower Zn concentration, whereas at 77 K, the echo amplitude does not vanish completely (except for pure Zn-ferrite). However, in Mössbauer spectroscopy at RT, we have observed magnetically ordered state of all the Li-Zn ferrite samples...
November 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29183004/adaptive-suppression-of-power-line-interference-in-ultra-low-field-magnetic-resonance-imaging-in-an-unshielded-environment
#7
Xiaolei Huang, Hui Dong, Yang Qiu, Bo Li, Quan Tao, Yi Zhang, Hans-Joachim Krause, Andreas Offenhäusser, Xiaoming Xie
Power-line harmonic interference and fixed-frequency noise peaks may cause stripe-artifacts in ultra-low field (ULF) magnetic resonance imaging (MRI) in an unshielded environment and in a conductively shielded room. In this paper we describe an adaptive suppression method to eliminate these artifacts in MRI images. This technique utilizes spatial correlation of the interference from different positions, and is realized by subtracting the outputs of the reference channel(s) from those of the signal channel(s) using wavelet analysis and the least squares method...
November 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29183003/direct-hyperpolarization-of-micro-and-nanodiamonds-for-bioimaging-applications-considerations-on-particle-size-functionalization-and-polarization-loss
#8
Grzegorz Kwiatkowski, Fabian Jähnig, Jonas Steinhauser, Patrick Wespi, Matthias Ernst, Sebastian Kozerke
Due to the inherently long relaxation time of 13C spins in diamond, the nuclear polarization enhancement obtained with dynamic nuclear polarization can be preserved for a time on the order of about one hour, opening up an opportunity to use diamonds as a new class of long-lived contrast agents. The present communication explores the feasibility of using 13C spins in directly hyperpolarized diamonds for MR imaging including considerations for potential in vivo applications.
November 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29179023/validation-of-a-low-field-rheo-nmr-instrument-and-application-to-shear-induced-migration-of-suspended-non-colloidal-particles-in-couette-flow
#9
A A Colbourne, T W Blythe, R Barua, S Lovett, J Mitchell, A J Sederman, L F Gladden
Nuclear magnetic resonance rheology (Rheo-NMR) is a valuable tool for studying the transport of suspended non-colloidal particles, important in many commercial processes. The Rheo-NMR imaging technique directly and quantitatively measures fluid displacement as a function of radial position. However, the high field magnets typically used in these experiments are unsuitable for the industrial environment and significantly hinder the measurement of shear stress. We introduce a low field Rheo-NMR instrument (1H resonance frequency of 10...
November 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29183002/an-mr-mri-compatible-core-holder-with-the-rf-probe-immersed-in-the-confining-fluid
#10
M Shakerian, B J Balcom
An open frame RF probe for high pressure and high temperature MR/MRI measurements was designed, fabricated, and tested. The open frame RF probe was installed inside an MR/MRI compatible metallic core holder, withstanding a maximum pressure and temperature of 5000 psi and 80 °C. The open frame RF probe was tunable for both 1H and 19F resonance frequencies with a 0.2 T static magnetic field. The open frame structure was based on simple pillars of PEEK polymer upon which the RF probe was wound. The RF probe was immersed in the high pressure confining fluid during operation...
November 15, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29169027/phase-modulated-2d-hsqc-tocsy-for-unambiguous-assignment-of-overlapping-spin-systems
#11
Amrinder Singh, Abhinav Dubey, Satish K Adiga, Hanudatta S Atreya
We present a new method that allows one to unambiguously resolve overlapping spin systems often encountered in biomolecular systems such as peptides and proteins or in samples containing a mixture of different molecules such as in metabolomics. We address this problem using the recently proposed phase modulation approach. By evolving the (1)H chemical shifts in a conventional two dimensional (2D) HSQC-TOCSY experiment for a fixed delay period, the phase/intensity of set of cross peaks belonging to one spin system are modulated differentially relative to those of its overlapping counterpart, resulting in their discrimination and recognition...
November 14, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29190515/b1-gradient-coherence-selection-using-a-tapered-stripline
#12
S G J van Meerten, K C H Tijssen, P J M van Bentum, A P M Kentgens
Pulsed-field gradients are common in modern liquid state NMR pulse sequences. They are often used instead of phase cycles for the selection of coherence pathways, thereby decreasing the time required for the NMR experiment. Soft off-resonance pulses with a B1 gradient result in a spatial encoding similar to that created by pulsed-field (B0) gradients. In this manuscript we show that pulse sequences with pulsed-field gradients can easily be converted to one which uses off-resonance B1 field gradient (OFFBEAT) pulses...
November 13, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29161649/magic-angle-spinning-nmr-below-6%C3%A2-k-with-a-computational-fluid-dynamics-analysis-of-fluid-flow-and-temperature-gradients
#13
Erika L Sesti, Nicholas Alaniva, Peter W Rand, Eric J Choi, Brice J Albert, Edward P Saliba, Faith J Scott, Alexander B Barnes
We report magic angle spinning (MAS) up to 8.5 kHz with a sample temperature below 6 K using liquid helium as a variable temperature fluid. Cross polarization (13)C NMR spectra exhibit exquisite sensitivity with a single transient. Remarkably, (1)H saturation recovery experiments show a (1)H T1 of 21 s with MAS below 6 K in the presence of trityl radicals in a glassy matrix. Leveraging the thermal spin polarization available at 4.2 K versus 298 K should result in 71 times higher signal intensity...
November 11, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29172170/a-pure-shift-experiment-with-increased-sensitivity-and-superior-performance-for-strongly-coupled-systems
#14
Julian Ilgen, Lukas Kaltschnee, Christina M Thiele
Motivated by the persisting need for enhanced resolution in solution state NMR spectra, pure shift techniques such as Zangger-Sterk decoupling have recently attracted widespread interest. These techniques for homonuclear decoupling offer enhanced resolution in one- and multidimensional proton detected experiments by simplifying multiplet structures. In this work, a modification to the popular Zangger-Sterk technique PEPSIE (Perfect Echo Pure Shift Improved Experiment) is presented, which decouples pairs of spins even if they share the same volume element...
November 6, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29121512/composite-pulse-and-partially-dipolar-dephased-multicp-for-improved-quantitative-solid-state-13-c-nmr
#15
Pu Duan, Klaus Schmidt-Rohr
Improved multiple cross polarization (multiCP) pulse sequences for quickly acquiring quantitative (13)C NMR spectra of organic solids are presented. Loss of (13)C magnetization due to imperfect read-out and storage pulses in multiCP has been identified as a significant mechanism limiting polarization enhancement for (13)C sites with weak couplings to (1)H. This problem can be greatly reduced by composite 90° pulses with non-orthogonal phases that flip the magnetization onto the spin-lock field and back to the longitudinal direction for the (1)H repolarization period; the observed loss is <3% for over ±10 kHz resonance offset and up to 20% flip-angle error...
November 6, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29126001/a-robust-heteronuclear-dipolar-recoupling-method-comparable-to-tedor-for-proteins-in-magic-angle-spinning-solid-state-nmr
#16
Zhengfeng Zhang, Jianping Li, Yanke Chen, Huayong Xie, Jun Yang
In this letter, we propose a robust heteronuclear dipolar recoupling method for proteins in magic-angle spinning (MAS) solid-state NMR. This method is as simple, robust and efficient as the well-known TEDOR in the aspect of magnetization transfer between (15)N and (13)C. Deriving from our recent band-selective dual back-to-back pulses (DBP) (Zhang et al., 2016), this method uses new phase-cycling schemes to realize broadband DBP (Bro-DBP). For broadband (15)N-(13)C magnetization transfer (simultaneous (15)N→(13)C' and (15)N→(13)Cα), Bro-DBP has almost the same (15)N→(13)Cα efficiency while offers 30-40% enhancement on (15)N→(13)C' transfer, compared to TEDOR...
October 31, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29112892/blipped-blipped-pure-phase-encoding-high-resolution-mri-with-low-amplitude-gradients
#17
Dan Xiao, Bruce J Balcom
MRI image resolution is proportional to the maximum k-space value, i.e. the temporal integral of the magnetic field gradient. High resolution imaging usually requires high gradient amplitudes and/or long spatial encoding times. Special gradient hardware is often required for high amplitudes and fast switching. We propose a high resolution imaging sequence that employs low amplitude gradients. This method was inspired by the previously proposed PEPI (π Echo Planar Imaging) sequence, which replaced EPI gradient reversals with multiple RF refocusing pulses...
October 31, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29127944/an-experimental-validation-of-a-bayesian-model-for-quantification-in-nmr-spectroscopy
#18
Yevgen Matviychuk, Erik von Harbou, Daniel J Holland
The traditional peak integration method for quantitative analysis in nuclear magnetic resonance (NMR) spectroscopy is inherently limited by its ability to resolve overlapping peaks and is susceptible to noise. The alternative model-based approaches not only extend quantification capabilities to these challenging examples but also provide a means for automation of the entire process of NMR data analysis. In this paper, we present a general model for an NMR signal that, in a principled way, takes into account the effects of chemical shifts, relaxation, lineshape imperfections, phasing, and baseline distortions...
October 23, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29102821/direct-enhancement-of-nitrogen-15-targets-at-high-field-by-fast-adapt-sabre
#19
Soumya S Roy, Gabriele Stevanato, Peter J Rayner, Simon B Duckett
Signal Amplification by Reversible Exchange (SABRE) is an attractive nuclear spin hyperpolarization technique capable of huge sensitivity enhancement in nuclear magnetic resonance (NMR) detection. The resonance condition of SABRE hyperpolarization depends on coherent spin mixing, which can be achieved naturally at a low magnetic field. The optimum transfer field to spin-1/2 heteronuclei is technically demanding, as it requires field strengths weaker than the earth's magnetic field for efficient spin mixing...
October 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29102820/dipolar-filtered-magic-sandwich-echoes-as-a-tool-for-probing-molecular-motions-using-time-domain-nmr
#20
Jefferson G Filgueiras, Uilson B da Silva, Giovanni Paro, Marcel N d'Eurydice, Márcio F Cobo, Eduardo R deAzevedo
We present a simple (1)H NMR approach for characterizing intermediate to fast regime molecular motions using (1)H time-domain NMR at low magnetic field. The method is based on a Goldmann Shen dipolar filter (DF) followed by a Mixed Magic Sandwich Echo (MSE). The dipolar filter suppresses the signals arising from molecular segments presenting sub kHz mobility, so only signals from mobile segments are detected. Thus, the temperature dependence of the signal intensities directly evidences the onset of molecular motions with rates higher than kHz...
October 20, 2017: Journal of Magnetic Resonance
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