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 Applied Magnetic Resonance   [SJR: 0.358]   [H-I: 34]   [4 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1613-7507 - ISSN (Online) 0937-9347    Published by Springer-Verlag  [2353 journals]
• The Frequency Shifts of the Nuclear Magnetic Momenta Larmor Precession in
the Mixture of Two Noble Gases
• Authors: E. N. Popov; K. A. Barantsev; A. N. Litvinov; V. A. Reshetov; A. N. Shevchenko
Pages: 761 - 770
Abstract: Abstract The dynamics of nuclear magnetization in the mixture of two noble gases with different gyromagnetic ratios of the nuclei is studied theoretically. The nuclear magnetization is induced by the radiofrequency electromagnetic radiation, which causes the nuclear magnetic resonance in both types of noble gases in the mixture. Frequency shifts of the nuclear magnetic resonance appeared due to an interaction between different types of the noble gases is analytically predicted. The specifics of these shifts are such that they cannot be compensated by means of the external magnetic field. The nature of the magnetic field distortion in the cell caused by the nuclear magnetization is also discussed.
PubDate: 2017-08-01
DOI: 10.1007/s00723-017-0896-7
Issue No: Vol. 48, No. 8 (2017)

• Broadband Excitation by Method of Double Sweep
• Authors: Navin Khaneja; Ashutosh Kumar
Pages: 771 - 782
Abstract: Abstract The paper describes the design of broadband excitation pulses in high resolution nuclear magnetic resonance (NMR) by method of double sweep. We first show the design of a pulse sequence that produces broadband excitation to the equator of Bloch sphere with phase linearly dispersed as frequency. We show how this linear dispersion can then be refocused by nesting free evolution between two adiabatic inversions (sweeps). We then show how this construction can be generalized to exciting arbitrary large bandwidths without increasing the peak rf-amplitude and by incorporating more adiabatic sweeps. Finally, we show how the basic design can then be modified to give a broadband x rotation over arbitrary large bandwidth and with limited rf-amplitude. Experimental excitation profiles for the residual HDO signal in a sample of $$99.5\%$$ D $$_2$$ 0 are displayed as a function of resonance offset. Application of the excitation is shown for $$^{13}$$ C excitation in a labelled sample of alanine.
PubDate: 2017-08-01
DOI: 10.1007/s00723-017-0894-9
Issue No: Vol. 48, No. 8 (2017)

• Structural Analysis of Relaxation Curves in MRI
• Authors: Alexey V. Protopopov
Pages: 783 - 794
Abstract: Abstract In magnetic resonance imaging, the gradient recalled echo sequence preserves information about spatial heterogeneities of magnetic field within a voxel, providing additional opportunity for classification of biological tissues. All the information, composed of physically meaningful parameters, like proton density, spin–spin relaxation time T 2, gradients of magnetic field and spin–spin relaxation, effective relaxation time $$T_{2}^{*}$$ , and many others, is encoded in the shape of a relaxation curve, which is more complicated than a pure monoexponent, traditionally observed in spin echo sequences. The previous work [A. Protopopov, Appl. Magn. Reason. 48, 255-274 (2017)], introduced the theory and basic algorithms for separation of those parameters. The present work further expands this theory to the case of spin–spin relaxation gradients, improves reliability of the algorithms, introduces physical explanation of the phenomenon previously known as “multiexponentiality”, and presents new validation of the algorithms on volunteers. The entire approach may be named the structural analysis of relaxation curves.
PubDate: 2017-08-01
DOI: 10.1007/s00723-017-0890-0
Issue No: Vol. 48, No. 8 (2017)

• Microwave Spin Frequency Comb Memory Protocol Controlled by Gradient
Magnetic Pulses
• Authors: K. I. Gerasimov; S. A. Moiseev; R. B. Zaripov
Pages: 795 - 804
Abstract: Abstract We have demonstrated a combination of frequency comb spin-echo protocol in a conventional microwave pulsed electron spin resonance spectrometer with gradient pulses of the external magnetic field applied for on-demand retrieval of signal microwave pulses at the required moments of time. A natural high-finesse periodic structure was used as a carrier of stored information. The structure is made out of hyperfine lines of electron spin resonance of tetracyanoethylene anion radicals in toluene at room temperature. Herein, we have also observed that using the pulses of gradient magnetic field can increase the memory capacity. The experimental results demonstrated promising opportunities for controlling electron nuclear spin coherence, which could be useful for implementation of broadband microwave or optical-microwave noise free quantum memory protocols.
PubDate: 2017-08-01
DOI: 10.1007/s00723-017-0892-y
Issue No: Vol. 48, No. 8 (2017)

• A Pulse EPR 25 mT Magnetometer with 10 ppm Resolution
• Authors: Subramanian V. Sundramoorthy; Boris Epel; Howard J. Halpern
Pages: 805 - 811
Abstract: Abstract A magnetometer designed for permanent magnet manufacturing and operated around 25 mT with 10 ppm absolute accuracy is described. The magnetometer uses pulse electron paramagnetic resonance methodology. The use of a pulsed broadband acquisition allowed reliable measurements in the presence of the magnetic field gradient and in relatively inhomogeneous magnetic fields of un-shimmed magnets.
PubDate: 2017-08-01
DOI: 10.1007/s00723-017-0902-0
Issue No: Vol. 48, No. 8 (2017)

• Trinuclear Gd(III) Metal Complex with Amide Core Display Remarkable
Enhancement in Relaxivity
• Authors: T. Lurthu Pushparaj; V. Alexander
Pages: 813 - 825
Abstract: Abstract New trinuclear gadolinium(III) complex having 2-bromoisovaleric acid pendant arm is reported. The longitudinal relaxivity (r 1p) of the complex is 23.17 mM−1 s−1 which correspond to a “per Gd” relaxivity of 7.72 mM−1 s−1. The transverse relaxivity (r 2p) of the complex is 24.79 mM−1 s−1 which correspond to a “per Gd” value of 8.26. The complex exhibit r 1p and r 2p values of 29.19 and 35.20, respectively, in the presence of HSA. The complex also shows pH dependant relaxivity which is an added advantage of the complex for utilization in cancer cell magnetic resonance imaging. The higher relaxivity values in water and HSA indicates a compact solution structure for the complexes and a restricted internal motion about the amide spacer.
PubDate: 2017-08-01
DOI: 10.1007/s00723-017-0901-1
Issue No: Vol. 48, No. 8 (2017)

• High-Field Electron Paramagnetic Resonance Reveals a Stable Glassy
Fraction up to Melting in Semicrystalline Poly(dimethylsiloxane)
• Authors: Carlo Andrea Massa; Silvia Pizzanelli; Vasile Bercu; Luca Pardi; Dino Leporini
Pages: 827 - 840
Abstract: Abstract The reorientation of the guest 4-methoxy-TEMPO (spin probe) in the disordered fraction of semicrystalline poly(dimethylsiloxane) (PDMS) is investigated by high-field electron paramagnetic resonance (HF-EPR) at 190 and 285 GHz. Accurate numerical simulations of the HF-EPR lineshapes evidence that the reorientation times of the spin probes are distributed between the melting temperature $$T_{\rm m}$$ and $$T_{\rm m}$$ —30 K. The distribution exhibits, in addition to a broad component, a narrow component with low mobility up to the PDMS melting point. It is shown that the temperature dependence of the reorientation time of the spin probes with low mobility is the same of the spin probes in glassy PDMS. The result suggests that the low-mobility fraction is localized in the so-called rigid amorphous fraction.
PubDate: 2017-08-01
DOI: 10.1007/s00723-017-0903-z
Issue No: Vol. 48, No. 8 (2017)

• Electron Paramagnetic Resonance Investigations of ZnSe:Mn Nanocrystals
• Authors: D. S. Mazing; A. V. Nikiforova; A. S. Osinin; V. A. Moshnikov; Yu. V. Bogachev; S. M. Sukharzhevskii
Pages: 731 - 737
Abstract: Abstract Colloidal nanocrystals of ZnSe doped with Mn2+ were synthesized in non-polar medium using hot-injection technique. Obtained samples were characterized by means of photoluminescence and absorption spectroscopies. To confirm the incorporation of Mn2+ impurity and to reveal its state and localization, electron paramagnetic resonance (EPR) spectroscopy was employed. As a result, EPR spectra were analyzed and hyperfine splitting constant and g-factor for Mn2+ dopant were determined.
PubDate: 2017-07-01
DOI: 10.1007/s00723-017-0898-5
Issue No: Vol. 48, No. 7 (2017)

• NMR Study Conformations of Calcium Gluconate in the Aqueous Solution
• Authors: M. M. Akhmetov; G. N. Konygin; D. S. Rybin; V. Yu. Petukhov; G. G. Gumarov; A. B. Konov
Abstract: Abstract Different spatial structures that arise due to rotation around simple bonds without violating the integrity of the molecule (without breaking chemical bonds) are called conformations. 1H nuclear magnetic resonance (NMR) study of the spatial structure of calcium gluconate in the aqueous solution has been carried out. It was shown that molecules of calcium gluconate exist in the form of two conformations: zigzag 1-P and cyclic 3 G +. The results of homonuclear 2D 1H NMR spectroscopy indicate the predominantly zigzag conformation. It was found that the intermolecular hydrogen bonds are formed and the spatial structure of molecules changes at the increase in the solution concentration. The observed concentration behavior of the conformation of calcium gluconate is also associated with the presence of the intramolecular hydrogen bonds –O(C4)H··O(C2).
PubDate: 2017-07-29
DOI: 10.1007/s00723-017-0918-5

• Joint Reconstruction of Multi-contrast Images and Multi-channel Coil
Sensitivities
• Authors: Zhongzhou Chen; Yanan Ren; Shi Su; Caiyun Shi; Jim X. Ji; Hairong Zheng; Xin Liu; Guoxi Xie
Abstract: Abstract Magnetic resonance imaging (MRI) has an important feature that it provides multiple images with different contrasts for complementary diagnostic information. However, a large amount of data is needed for multi-contrast images depiction, and thus, the scan is time-consuming. Many methods based on parallel magnetic resonance imaging (pMRI) and compressed sensing (CS) are applied to accelerate multi-contrast MR imaging. Nevertheless, the image reconstructed by sophisticated pMRI methods contains residual aliasing artifact that degrades the quality of the image when the acceleration factor is high. Other methods based on CS always suffer the regularization parameter-selecting problem. To address these issues, a new method is presented for joint multi-contrast image reconstruction and coil sensitivity estimation. The coil sensitivities can be shared during the reconstruction due to the identity of coil sensitivity profiles of different contrast images for imaging stationary tissues. The proposed method uses the coil sensitivities as sharable information during the reconstruction to improve the reconstruction quality. As a result, the residual aliasing artifact can be effectively removed in the reconstructed multi-contrast images even if the acceleration factor is high. Besides, as there is no regularization term in the proposed method, the troublesome regularization parameter selection in the CS can also be avoided. Results from multi-contrast in vivo experiments demonstrated that multi-contrast images can be jointly reconstructed by the proposed method with effective removal of the residual aliasing artifact at a high acceleration factor.
PubDate: 2017-07-27
DOI: 10.1007/s00723-017-0919-4

• Saturation Recovery EPR Spin-Labeling Method for Quantification of Lipids
in Biological Membrane Domains
• Authors: Laxman Mainali; Theodore G. Camenisch; James S. Hyde; Witold K. Subczynski
Abstract: Abstract The presence of integral membrane proteins induces the formation of distinct domains in the lipid bilayer portion of biological membranes. Qualitative application of both continuous wave (CW) and saturation recovery (SR) electron paramagnetic resonance (EPR) spin-labeling methods allowed discrimination of the bulk, boundary, and trapped lipid domains. A recently developed method, which is based on the CW EPR spectra of phospholipid (PL) and cholesterol (Chol) analog spin labels, allows evaluation of the relative amount of PLs (% of total PLs) in the boundary plus trapped lipid domain and the relative amount of Chol (% of total Chol) in the trapped lipid domain (Raguz et al. Exp Eye Res 140:179–186, 24). Here, a new method is presented that, based on SR EPR spin-labeling, allows quantitative evaluation of the relative amounts of PLs and Chol in the trapped lipid domain of intact membranes. This new method complements the existing one, allowing acquisition of more detailed information about the distribution of lipids between domains in intact membranes. The methodological transition of the SR EPR spin-labeling approach from qualitative to quantitative is demonstrated. The abilities of this method are illustrated for intact cortical and nuclear fiber cell plasma membranes from porcine eye lenses. Statistical analysis (Student’s t test) of the data allowed determination of the separations of mean values above which differences can be treated as statistically significant (P ≤ 0.05) and can be attributed to sources other than preparation/technique.
PubDate: 2017-07-22
DOI: 10.1007/s00723-017-0921-x

• Comparison of 12 Quadrature Birdcage Coils with Different Leg Shapes at
9.4 T
• Authors: Yongfeng Xu; Qingqing Wen
Abstract: Abstract The purpose of this study was to analyse the relationship between the radio frequency (RF) coil performance and conductor surface shape for ultra-high field (UHF) magnetic resonance imaging. Twelve different leg-shaped quadrature birdcage coils were modeled and built, e.g., 4 mm-width-leg conventional birdcage coil, 7 mm-width-leg conventional birdcage, 10 mm-width-leg conventional birdcage coil, 13 mm-width-leg conventional birdcage coil, inside arc-shape-leg birdcage coil, outward arc-shape-leg birdcage coil, inside right angle-shape-leg birdcage coil, outward right angle-shape-leg birdcage coil, vertical 4 mm-width-leg vertical birdcage, 6 mm-width-leg vertical birdcage, 8 mm-width-leg vertical birdcage and 10 mm-width-leg vertical birdcage. Studies were carried out in both electromagnetic simulations with finite element method as well as in vitro saline phantom experiments at 9.4 T. Both the results of simulation and experiment showed that conventional birdcage coil produces the highest signal-to-noise ratio (SNR) while the vertical birdcage coil produces the most homogeneous RF magnetic (B 1) field at UHF. For conventional birdcage coils, as well as the vertical birdcage coils, only the proper width of legs results in the best performance (e.g., B 1 homogeneous and SNR). For vertical birdcage coils, the wider the leg size, the higher RF magnetic (B 1) field intensity distribution.
PubDate: 2017-07-19
DOI: 10.1007/s00723-017-0920-y

• The Power of EPR Techniques in Investigating Functionalization and
Penetration into Fibers of Cotton-Bound Antimicrobial Peptides
• Authors: S. A. Dzuba; M. N. Uvarov; D. E. Utkin; F. Formaggio; A. Bedon; A. Orlandin; C. Peggion
Abstract: Abstract The development of protective and safe textiles is of fundamental importance for defending the human body from bacterial infections. To this aim, garments are often functionalized with antibacterial agents. We recently started a program aimed at covalently linking antimicrobial peptides to cotton tissues. To optimize the process of binding, it is necessary to know the degree of functionalization and how deeply peptides penetrate into the cotton fiber. Here, we present a spin-label electron paramagnetic resonance (EPR) approach for obtaining data on the peptide incorporation into the fibers. The approach is based on the line broadening in conventional EPR and on the signal decays in electron spin echo spectroscopy that is a pulsed version of EPR.
PubDate: 2017-07-17
DOI: 10.1007/s00723-017-0917-6

• Erratum to: Consistent Paradigm of the Spectra Decomposition into
Independent Resonance Lines
• Authors: K. M. Salikhov
PubDate: 2017-07-08
DOI: 10.1007/s00723-017-0915-8

• 13 C Dynamic Nuclear Polarization Using Derivatives of TEMPO Free Radical
• Authors: Peter Niedbalski; Christopher Parish; Qing Wang; Andhika Kiswandhi; Lloyd Lumata
Abstract: Abstract The nitroxide-based 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) free radical is widely used in 13C dynamic nuclear polarization (DNP) due to its relatively low cost, commercial availability, and effectiveness as polarizing agent. While a large number of TEMPO derivatives are available commercially, so far, only few have been tested for use in 13C DNP. In this study, we have tested and evaluated the 13C hyperpolarization efficiency of eight derivatives of TEMPO free radical with different side arms in the 4-position. In general, these TEMPO derivatives were found to have slight variations in efficiency as polarizing agents for DNP of 3 M [1-13C] acetate in 1:1 v/v ethanol:water at 3.35 T and 1.2 K. X-band electron paramagnetic resonance (EPR) spectroscopy revealed no significant differences in the spectral features among these TEMPO derivatives. 2H enrichment of the ethanol:water glassing matrix resulted in further improvement of the solid-state 13C DNP signals by factor of 2 to 2.5-fold with respect to the 13C DNP signal of non-deuterated DNP samples. These results suggest an interaction between the nuclear Zeeman reservoirs and the electron dipolar system via the thermal mixing mechanism.
PubDate: 2017-07-08
DOI: 10.1007/s00723-017-0916-7

• The Morpho-Functional Characteristics of Cerebral and Renal Arteries After
Induced Arterial Hypertension in Rats Using Magnetic Resonance Imaging
• Authors: Irina G. Agafonova; Vladimir N. Kotelnikov; Boris I. Geltcer; Natalya G. Kolosova; Valentin A. Stonik
Abstract: Abstract The morpho-functional reorganization of regional vascular arteries is greatly altered after the induction of arterial hypertension (AH) in experimental rats. These changes can be examined using magnetic resonance imaging methods. In our experiment, induced AH caused arteriostenosis of cerebral arteries in two strains of rats—Wistar and OXYS (p < 0.05). In addition, we studied the changes in renal arteries in the same experiment. Compensatory vasodilatation was found in the extrarenal part of arteries. Arteriostenosis was detected in the intrarenal part of arteries, which was due to cytotoxic hypostasis of renal parenchyma. We proposed a cerebral vascular index and applied this index for precise analysis of changes in the studied arteries. This index is calculated as the ratio of the diameter of cerebral arteries to the diameter of renal arteries. The degree of differences in vasoconstriction between cerebral and renal arteries was established. Our results showed a moderate degree of differences in the vasoconstriction of cerebral arteries. In addition, the degree of differences in the vasoconstriction of intrarenal arteries revealed deeper vasoconstriction. These distinctions are 28.1% (p < 0.05) and 60.9% (p < 0.05) for Wistar and OXYS rats, respectively. Arterial morphometry revealed reduced sizes of all OXYS rat arteries compared with those of Wistar rat arteries. These pathological changes were associated with excessive stiffness (rigidity) of vascular walls due to accelerated aging. The accelerated aging of OXYS rat arteries led to a decrease in their vasodilatation potential and a decrease in the blood supply of cerebral and renal arteries. Comparative morphometry of the status of all arteries in both groups after AH revealed multiple specific changes in the remodeled arteries.
PubDate: 2017-07-08
DOI: 10.1007/s00723-017-0914-9

• Structural and Metabolic Pattern Classification for Detection of
Glioblastoma Recurrence and Treatment-Related Effects
• Authors: Marija Jovanovic; Milica Selmic; Dragana Macura; Slobodan Lavrnic; Svetlana Gavrilovic; Marko Dakovic; Sandra Radenkovic; Ivan Soldatovic; Tatjana Stosic-Opincal; Ruzica Maksimovic
Abstract: Abstract Artificial neuronal network (ANN) in classification of glioblastoma multiforme (GBM) recurrence from treatment effects using advanced magnetic resonance imaging techniques was evaluated. In 56 patients with treated GBM, normalised minimal and mean apparent-diffusion coefficient (ADC) values, vessels number on susceptibility-weighted images (SWI) and Cho/Cr ratio were analysed statistically and by ANN. Significant correlation exists between normalised minimal and mean ADC values, and no correlation between ADC and Cho/Cr values. Cut-off values for tumour presence were: 1.14 for normalised minimal ADC (54% sensitivity, 71% specificity), 1.13 for normalised mean ADC (51% sensitivity, 71% specificity), 1.8 for Cho/Cr ratio (92% sensitivity, 82% specificity), grade 2 for SWI (87% sensitivity, 82% specificity). An accurate prediction of ANN to classify patients into GBM progression or treatment effects group was 99% during the training and 96.8% during the testing phase. Multi-parametric ANN allows distinction between GBM recurrence and treatment effects, and can be used in clinical practice.
PubDate: 2017-07-06
DOI: 10.1007/s00723-017-0913-x

• Superconducting Fluctuations Above the Critical Temperature in Bi 2 Sr 2
Ca 1−x Y x Cu 2 O 8+δ as Revealed by Microwave Absorption
• Authors: I. Gimazov; Yu. Talanov; V. Sakhin; T. Adachi; T. Noji; Y. Koike
Abstract: Abstract The superconducting fluctuations above the critical temperature in Bi2Sr2Ca1−x Y x Cu2O8+δ (x = 0–0.3) single crystals are studied by microwave absorption (MWA). The maximum in the MWA temperature dependence was observed close to the critical temperature. Its formation is explained by the change of the quasiparticle density of states due to superconducting fluctuations. The fluctuation area boundary is plotted on the phase diagram using the variation of the MWA temperature dependence with the hole density and is compared with the pseudogap phase behavior.
PubDate: 2017-07-04
DOI: 10.1007/s00723-017-0912-y

• Compressed Sensing MRI Using Sparsity Averaging and FISTA
• Authors: Jian-ping Huang; Liang-kuan Zhu; Li-hui Wang; Wen-long Song
Abstract: Abstract Magnetic resonance imaging (MRI) is widely adopted for clinical diagnosis due to its non-invasively detection. However, acquisition of full k-space data limits its imaging speed. Compressed sensing (CS) provides a new technique to significantly reduce the measurements with high-quality MR image reconstruction. The sparsity of the MR images is one of the crucial bases of CS-MRI. In this paper, we present to use sparsity averaging prior for CS-MRI reconstruction in the basis of that MR images have average sparsity over multiple wavelet frames. The problem is solved using a Fast Iterative Shrinkage Thresholding Algorithm (FISTA), each iteration of which includes a shrinkage step. The performance of the proposed method is evaluated for several types of MR images. The experiment results illustrate that our approach exhibits a better performance than those methods that using redundant frame or a single orthonormal basis to promote sparsity.
PubDate: 2017-06-27
DOI: 10.1007/s00723-017-0910-0

• Respiratory Motion Correction of Compressively Sampled Myocardial
Perfusion Data by Using Robust Matrix Decomposition
• Authors: Abdul Haseeb Ahmed; Ijaz M. Qureshi; M. Habib Mahmood
Abstract: Abstract Motion correction is a challenging problem in free breathing undersampled cardiac perfusion magnetic resonance images. It is due to aliasing artifacts in the reconstructed images and the rapid contrast changes in the perfusion images. In addition to the reconstruction limitations, many registration algorithms underperforms in the presence of the rapid intensity changes. In this paper, we propose a novel motion correction technique that reconstructs the motion-free images from the undersampled cardiac perfusion MR data. The technique utilizes the robust principal component analysis along with the periodic decomposition to separate the respiratory motion component that can be registered, from the unchanged contrast intensity variations. It was tested on synthetic data, simulated data, and the clinically acquired data. The performance of the method was qualitatively assessed and validated by comparing manually acquired time–intensity curves of the myocardial sectors to automatically generated curves before and after registration.
PubDate: 2017-06-22
DOI: 10.1007/s00723-017-0907-8

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