The influence of longitudinal magnetic-field gradient on the transverse relaxation rate of cesium atoms

Abstract The transverse relaxation rate T2-1 was measured in YBa2Cu3O7 from 4.2 to 100 K in zero magnetic field. It showed a sudden drop just below T c down to 1/3 of that above Tc . A cusp-shaped sharp peak of T2-1 was found at 35 K for Cu(2) (plane) site, but not for Cu(l) (chain) site. Except the peak, all the behavior can be interpreted by the model of Pennington et al. that the origin of T2-1 at 100 K is mainly the local field fluctuation by the Cu d-electron and secondly the indirect nuclear spin-spin coupling via superexchange interaction between Cu-ions. Below Tc the former is sup-pressed.

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Transverse relaxation of spin-polarizedHe3gas due to a magnetic field gradient

Physical Review A ◽

10.1103/physreva.41.2631 ◽

1990 ◽

Vol 41 (5) ◽

pp. 2631-2635 ◽

Cited By ~ 50

Author(s):

Douglas D. McGregor

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Magnetic Field Gradient ◽

Transverse Relaxation

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Detailing magnetic field strength dependence and segmental artifact distribution of myocardial effective transverse relaxation rate at 1.5, 3.0, and 7.0 T

Magnetic Resonance in Medicine ◽

10.1002/mrm.24856 ◽

2013 ◽

Vol 71 (6) ◽

pp. 2224-2230 ◽

Cited By ~ 19

Author(s):

Antonella Meloni ◽

Fabian Hezel ◽

Vincenzo Positano ◽

Petra Keilberg ◽

Alessia Pepe ◽

...

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Relaxation Rate ◽

Magnetic Field Strength ◽

Transverse Relaxation Rate ◽

Transverse Relaxation ◽

Strength Dependence

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Spectroscopic imaging of human disease

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100166889 ◽

1996 ◽

Vol 54 ◽

pp. 884-885

Author(s):

D.J. Meyerhoff

Keyword(s):

Magnetic Field ◽

Magnetic Resonance ◽

Field Gradient ◽

Human Disease ◽

Morphological Changes ◽

Magnetic Field Gradient ◽

Spectroscopic Imaging ◽

Resonance Spectroscopy ◽

Tissue Water

Magnetic Resonance Imaging (MRI) observes tissue water in the presence of a magnetic field gradient to study morphological changes such as tissue volume loss and signal hyperintensities in human disease. These changes are mostly non-specific and do not appear to be correlated with the range of severity of a certain disease. In contrast, Magnetic Resonance Spectroscopy (MRS), which measures many different chemicals and tissue metabolites in the millimolar concentration range in the absence of a magnetic field gradient, has been shown to reveal characteristic metabolite patterns which are often correlated with the severity of a disease. In-vivo MRS studies are performed on widely available MRI scanners without any “sample preparation” or invasive procedures and are therefore widely used in clinical research. Hydrogen (H) MRS and MR Spectroscopic Imaging (MRSI, conceptionally a combination of MRI and MRS) measure N-acetylaspartate (a putative marker of neurons), creatine-containing metabolites (involved in energy processes in the cell), choline-containing metabolites (involved in membrane metabolism and, possibly, inflammatory processes),

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Proton magnetic relaxation of water sorbed by methaemoglobin crystals

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1973.0002 ◽

1973 ◽

Vol 331 (1587) ◽

pp. 457-468 ◽

Cited By ~ 1

Keyword(s):

Relaxation Rate ◽

Relaxation Times ◽

Transverse Relaxation Rate ◽

Ferric Ions ◽

Transverse Relaxation ◽

Water Binding ◽

Adsorption Sites ◽

Protein Molecules ◽

Proton Magnetic Relaxation ◽

Limiting Value

P. m. r. relaxation times ( T 1 and T 2 ) have been measured as a function of regain and temperature for water sorbed by lyophilized methaemoglobin. The purpose of the work was to gain information regarding the nature and extent of water binding by the protein molecules. The T 1 results are interpreted in terms of an exchange between the sixth ligand position of the Fe (III) and other adsorption sites on the protein. At high temperatures the relaxation rate at a given regain reaches a limiting value which allows the fraction of ferric ions hydrated to be calculated. Above 16% regain all the Fe (III) is hydrated. At 21 and 35% regains a maximum appears in the relaxation rate at about -46 °C indicating a contribution from a more mobile phase which produces a T 1 minimum at that temperature. The T 2 data are consistent with a model in which the main contribution to the transverse relaxation rate comes from a tightly bound fraction of the water with ω 0 Ƭ c ≫1. The temperature dependence of T 2 exhibits three different regions: ( a ) a low temperature region where lg T 2 ∝ T -1 ; ( b ) an intermediate region with a steeper increase of T 2 with temperature; and ( c ) a high temperature where T 2 levels off.

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Magnetic hybrid materials interact with biological matrices

Physical Sciences Reviews ◽

10.1515/psr-2019-0114 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Christine Gräfe ◽

Elena K. Müller ◽

Lennart Gresing ◽

Andreas Weidner ◽

Patricia Radon ◽

...

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Hybrid Materials ◽

Biomedical Application ◽

Magnetic Field Gradient ◽

Apical Cell ◽

Cell Type ◽

Cell Layers ◽

Barrier Model

Abstract Magnetic hybrid materials are a promising group of substances. Their interaction with matrices is challenging with regard to the underlying physical and chemical mechanisms. But thinking matrices as biological membranes or even structured cell layers they become interesting with regard to potential biomedical applications. Therefore, we established in vitro blood-organ barrier models to study the interaction and processing of superparamagnetic iron oxide nanoparticles (SPIONs) with these cellular structures in the presence of a magnetic field gradient. A one-cell-type–based blood-brain barrier model was used to investigate the attachment and uptake mechanisms of differentially charged magnetic hybrid materials. Inhibition of clathrin-dependent endocytosis and F-actin depolymerization led to a dramatic reduction of cellular uptake. Furthermore, the subsequent transportation of SPIONs through the barrier and the ability to detect these particles was of interest. Negatively charged SPIONs could be detected behind the barrier as well as in a reporter cell line. These observations could be confirmed with a two-cell-type–based blood-placenta barrier model. While positively charged SPIONs heavily interact with the apical cell layer, neutrally charged SPIONs showed a retarded interaction behavior. Behind the blood-placenta barrier, negatively charged SPIONs could be clearly detected. Finally, the transfer of the in vitro blood-placenta model in a microfluidic biochip allows the integration of shear stress into the system. Even without particle accumulation in a magnetic field gradient, the negatively charged SPIONs were detectable behind the barrier. In conclusion, in vitro blood-organ barrier models allow the broad investigation of magnetic hybrid materials with regard to biocompatibility, cell interaction, and transfer through cell layers on their way to biomedical application.

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