The In Situ Study of the Fe 3 O 4 /DMSO Ferrofluid Synthesis Abstract Electron spin resonance in situ was applied to study the initial stages of ferrofluid formation in combination with the X-ray diffraction, high-resolution transmission electron microscopy and Fourier transform infrared spectroscopy studies data. The ultrafine (d = 4 nm) magnetite in dimethylsulfoxide ferrofluid with a narrow size nanoparticles distribution was obtained in a single step at room temperature by admixing butylene oxide to a solution of iron (II) and (III) chlorides in dimethylsulfoxide. It has been shown that at the first step of the ferrofluid synthesis antiferromagnetically ordered iron containing phase is formed, which can be correlated with iron hydroxides.

Persistence of Nitroxide Radicals in Solution Abstract Data on long-term persistence of nitroxide radicals typically are focused on solid samples. Less information is available for nitroxides in fluid solution. Sealed deoxygenated solutions of a doxyl nitroxide in tetrahydrofuran and a piperidinyl nitroxide in toluene in 4 mm EPR tubes were kept in a laboratory environment at ambient temperature and without protection from light. After more than 40 years, the concentrations of the solutions had decreased by about factors of 12 and 6, respectively. The longevity in solution probably depends strongly on the purity of the solvent, but these results indicate remarkable persistence.

Correction to: Spin-label Order Parameter Calibrations for Slow Motion In the print published article, some equations were published incorrectly, the correct equations are given below.

Studies of the Local Distortions for Cu 2+ in Ba 2 Zn(HCOO) 6 ·4H 2 O Single Crystal Abstract The high-order perturbation formulas of the electron paramagnetic resonance (EPR) parameters for an orthorhombically elongated octahedral 3d9 cluster are adopted to analyze the local distortions of divalent copper in Ba2Zn(HCOO)6·4H2O (BZFA). The doped Cu2+ may substitute the host Zn2+ in the lattice, with different local environments from the original Zn2+, which can strongly affect its EPR parameters. In the calculations, the admixture of d-orbitals in the ground state for the impurity Cu2+ ion under orthorhombic symmetry is considered, and the required molecular orbital coefficients are determined from the cluster approach. The orthorhombic field parameters are correlated with the local lattice distortion (characterized by the axial elongation δz and the relative perpendicular bond length variation δr) and can be calculated from the superposition model. The theoretical EPR parameters based on the above local structure are in good agreement with the observed values, and the results are discussed.

The Use of Magnetic Resonance Imaging for the Evaluation of the Porcine Intervertebral Disc Condition Under Treatment Abstract One of the methods of evaluation of degenerative disc disease therapies’ effectiveness is the use of animal models and magnetic resonance imaging (MRI), for the evaluation of the degree of damage and possible subsequent regeneration of intervertebral discs (IVDs). The purpose of our study was to propose the methodology that can be used for assessing the condition of the porcine IVDs based on scans obtained in MRI study. Our research is based on the MRI scans obtained for the purpose of evaluation of the process of IVDs regeneration after administration of mesenchymal stem cells isolated from bone marrow after the damage caused by the surgical laser vaporization. Proposed method of segmentation utilizes basic methods of digital image processing implemented with the use of Matlab environment. The outcome of the described method is binary mask giving direct information about locations of IVDs in MRI scans. We present the results of the IVD condition evaluation with the use of described method. We also present differences that may appear in the assessment of the same cases based on different cross-sections of the same MRI research. (1) The use of coronal imaging plane is recommended to use, as it can be indicated as more reliable than sagittal. (2) Use of the basic geometrical shapes as the discs’ shape approximation can lead to significant errors in the evaluation of the experiment results—the borders of IVDs should be determined using more complex shapes, i.e. considering the anatomy.

Proton Spin Relaxation in Aqueous Solutions of Self-assembling Gadolinium Endofullerenols Abstract The nuclear magnetic resonance (NMR)-relaxation characteristics of protons in pure aqueous and buffer solutions of highly hydroxylated endofullerenols with paramagnetic gadolinium ions at ambient temperature have been studied. These systems were thoroughly characterized by SANS and examined by NMR at various resonance frequencies: f = 2 kHz–500 MHz. In all the cases, we have discovered much higher longitudinal and transversal relaxation rates as compared to the reference salt solutions with Gd+3 ions in the same range of concentrations (0.1–10.0 mM/l). We suppose that this effect is due to the fact that the objects studied reveal well-manifested abilities to the self-assembly in acidic conditions. As a result, the transversal relaxation rate (1/T2) increases greatly, and also the longitudinal relaxation rate (1/T1) demonstrates a broad maximum at resonant frequencies f ~ 20–100 MHz that are determined by the time of fullerenol diffusive rotations. The relaxation rates, which increase linearly with fullerenol content (0.1–10.0 mM/l), testify the stable assembly. The studied features of fullerenol assembly and its strong influence on the proton relaxation make it possible to suppose good prospects of these metal–carbon structures for biomedical applications, in particular, as contrast agents in MRI.

Hyperbaric Oxygenation Effects on Human Brain In Vivo: 1H MRS and Resting-State fMRI Study Abstract Previously using 31P magnetic resonance spectroscopy (MRS) we have demonstrated that one hyperbaric oxygenation (HBO) session (with O2 pressure 1.2 atm) directly activates cerebral energetics: the decrease in creatine phosphate (PCr) and, possibly, the increase in nicotinamide adenine dinucleotide. The aim of this study is to elucidate the effect of one HBO session on the concentrations of metabolites detectible by 1H MRS, and on the connectivity in Default Mode Network. Absolute concentrations of the metabolites were calculated. The reduction of N-acetyl aspartate by 3% was found in mediolateral prefrontal cortex (MPFC) with p < 0.05 and in posterior cingulate cortex (p < 0.1). The resting-state functional connectivity between these zones was elevated by ~ 40%, p < 0.05 after HBO session. Glutamate levels remained unchanged after HBO. There is an indication in support of lactate growth in MPFC after HBO session. The demonstrated metabolic changes, as well as the decrease in PCr shown in previous study, may signify the activation of power supply processes to compensate the energy expenses connected with the enhancement of cerebral functional connectivity even after one HBO session.

Theoretical Treatment of Pulsed DNP Experiments: Effects of Spectral Exchange Abstract In the present work, we provide a theoretical treatment of pulsed Overhauser-type dynamic nuclear polarization (DNP) in the presence of spectral exchange, namely, Heisenberg exchange. The expression for the DNP enhancement of a nuclear magnetic resonance (NMR) signal is generalized by redefining the “deviation factor”, expressing the deviation of the electron spin polarization from its equilibrium value, averaged over the period of the pulse sequence. We can demonstrate that spectral exchange significantly increases the deviation factor and, thus, the NMR enhancement. The present treatment allows one to determine the optimal pumping frequency at different exchange rates.

Whole Body Sodium MRI at 0.5 Tesla Using Surface Coil and Long Echo Time Sequence Abstract Experiments on sodium (23Na) magnetic resonance imaging (MRI) of human organs, including the construction of whole body (WB) MRI, on a clinical 0.5-T scanner are described. The specificity of the research is their conduct in the presence of radio frequency (RF) interference, characterized by the frequency drift of the parasitic RF signal, which complicates its filtering. To solve this problem, the receiver bandwidth (BW) was set as narrow as possible, which, in turn, determined the low sampling rate and pulse sequence with relatively long echo time (TE)—12 ms, which is comparable to the transverse relaxation time of sodium nuclei. 23Na MRI on a 0.5-T clinical scanner was achieved without significant modifications in the hardware—only 20-cm square-shaped frame coil was made as a transceiver probe head. Scanning was performed using gradient echo method with in-plane resolution of (6.6 × 6.6) mm2 without slice selection. After processing the data in K-space, including exponential apodization, images were obtained in which human organs are represented with signal-to-noise ratio (SNR) up to several tens. The scans from nine individual segments of the human body in prone and supine positions were acquired to produce 23Na WB MRI. The time for one body segment scan was 30 min. The results of the work can be used to assess the potential capabilities of scanners of this class and to compare them with the data obtained using more advanced tools to assess their effectiveness.

Evidence of the Excitation of Mn 2+ Spin-Dependent Photoluminescence in Manganese-Doped Yttrium Aluminum Garnets Abstract Mn2+ ions in yttrium positions have been studied by means of optically detected magnetic resonance (ODMR) via Mn2+ spin-dependent emission in manganese-doped yttrium aluminum garnet crystals. It was shown that the intensity of photoluminescence excited by circularly polarized light depends on the population of the spin sublevels of the Mn2+ ground state and therefore can be used to study the ODMR. EPR measurements have confirmed that Mn2+ ions in the crystals under study occupy preferentially dodecahedral positions in the YAG lattice. Observation of forbidden transitions in the ODMR spectra has proved that the observed ODMR signals belong to Mn2+. Thus the wavelength dependence of the ODMR amplitude reveals the emission band of Mn2+ ions at dodecahedral positions in YAG:Mn.