Том 47, № 3 (2016)

Using the electron paramagnetic resonance (EPR) method, it was established that under aerobic conditions thiol (RS⁻) groups of thiol-containing ligands within the composition of paramagnetic mononuclear dinitrosyl iron complexes (M-DNIC) are converted into persulfide (RSS⁻) ligands in the presence of Na₂S in water-ethanolic solutions thereby initiating the formation of paramagnetic M-DNIC with persulfide ligands. Correspondingly, the EPR signal of M-DNIC with thiol-containing ligands at g_⊥ = 2.04, g_∥ = 2.014, and g_aver. = 2.031 is substituted for the EPR signal characteristic of M-DNIC with persulfide ligands at g_⊥ = 2.04, g_∥ = 2.02, and g_aver. = 2.033. With the increase in the registration temperature to ambient temperature, the anisotropic shape of the EPR signal of M-DNIC with persulfide ligands recorded at 77 K and determined by the anisotropy of the g-factor turns into the symmetric shape with a halfwidth of 0.3–0.4 mT. The lack of the five-component hyperfine structure (HFS) of this EPR signal caused by the interaction of the unpaired electron with the nitrogen nuclei of two nitrosyl ligands is attributed to the compensation of the differently charged contributions of isotropic HFS formed as a result of the spin polarization of appropriate molecular orbitals. It is suggested that similar to M-DNIC with thiol-containing ligands, M-DNIC with persulfide ligands are characterized by the d⁷ electronic configuration of the iron atom and the localization of the unpaired electron on MO(d_z2). The incorporation of ⁵⁷Fe into M-DNIC with persulfide ligands is accompanied by doublet HFS splitting of the EPR signal of M-DNIC by virtue of the mononuclear nature of the latter. It is concluded that M-DNIC with persulfide ligands may exist in the form of both low-molecular and protein-bound complexes and have relevance to the recently established biological activity of hydrogen sulfide and its derivatives.

The ¹H nuclear magnetic resonance (NMR) spectroscopy, NMR imaging, and pulsed field gradient NMR (PFG NMR) were applied for comparative study of moisture–polymer composite materials (PCM) interaction. The water uptake in PCM reinforced by aramid and carbon fibers was measured by NMR spectroscopy techniques. The aramid fiber-reinforced PCM absorbs water more intensively compared with PCM reinforced by carbon fiber, but both of them are retaining water inside of pores without formation of chemical bonds. Using NMR imaging the spatial distribution of water absorbed was visualized; preferable water pathways and influence of surface treatment on water-resistant properties were revealed. It was found that the surface rough treatment sufficiently improves the water absorption, but penetration of water molecules is still occurring only through the surfaces and it happens within a thin layer. PFG NMR technique revealed influence of pore structure on moisture–PCM interaction; it was found that additionally to strong hydrophobic properties of carbon fiber, the smaller total volume of pores sufficiently decrease the water uptake. Results achieved in this work demonstrate efficiency of NMR methods applied all together for investigation of PCM, and information obtained is practically important when designing advanced PCM with required properties.

Currently there is little report about the application of diffusion tensor imaging (DTI) technology to judge the prognosis of patients with cerebral apoplexy. This study was to investigate cerebral functional connection in both sides of the M1 area in patients with cerebral infarction, who were treated with transcranial magnetic stimulation (TMS), using DTI technology. Fifteen patients with cerebral infarction admitted to the hospital between February 2013 and August 2014 were enrolled for the study. The patients were treated with TMS and underwent DTI. The fractional anisotropy (FA), apparent diffusion coefficient (ADC), the relative FA value (rFA), and relative ADC values (rADC) were analyzed using paired t-test. rFA, rADC, and NIHSS of the lesion side before and after treatment were analyzed by Spearman correlation analysis. The results showed that before treatment, ADC value and FA value of the lesion side were lower than those of the contralateral healthy side with statistical significance (ADCt = 2.849, P < 0.05; FAt = 10.285, P < 0.05). Four weeks after treatment, ADC value and FA value of the lesion side were higher than those before treatment with statistical significance (ADCt = 6.206, P < 0.05; FAt = 3.788, P < 0.05). Both rFA values of pre-treatment and post-treatment showed negative correlation with NIHSS score with statistical significance (P < 0.05). In conclusion, after TMS with TDI technique, the value of FA and ADC values significantly increased compared to that of pre-treatment. It suggested that transcranial magnetic stimulation played a positive role in stroke rehabilitation.

The self-diffusion of water and lipids in water—mouse RBCs’ suspension was investigated by pulsed field gradient NMR technique at different diffusion times in temperature range from 5 to 35 °C. For the experimental data interpretation, the phenomenological scaling approach was applied. The intracellular water restriction size (2.1 μm), erythrocyte water permeability (about 10⁻⁵ m/s), intracellular residence time (about 20 ms), and water permeability activation energy (24.1 ± 1.9 kJ/mol) were calculated. The lipid self-diffusion coefficients are varied from 3 × 10⁻¹² to 10⁻¹¹ m²/s depending on temperature and diffusion time. The lipid lateral self-diffusion activation energy is about 25 ± 2.9 kJ/mol.