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Magnesium and its alloys are promising materials for manufacturing bioresorbable implants. Various combinations of thermo-mechanical processing are used to improve the mechanical properties and corrosion resistance of magnesium alloys, forming the necessary structural state, which, in turn, requires determining the influence of various structural factors (grains, grain boundaries, dislocations, second-phase particles, etc.) on the complex properties of 'strength - corrosion resistance'. In this study, an experiment was conducted to determine the influence of structural changes in pure magnesium on mechanical properties and corrosion resistance in a physiological environment after deformation using equal channel angular pressing (ECAP) and post-deformation ultrasonic treatment. It was found that ECAP and subsequent ultrasonic treatment lead to a twofold increase in the yield strength of magnesium from 30 to 60 MPa. The increase in microhardness after ECAP is 50 MPa, while ultrasonic treatment results in an increase in microhardness by 230 MPa. After deformation, corrosion resistance changes significantly: ECAP reduces the corrosion rate compared to the initial state of magnesium by approximately 7 times, to values of 7 mm/year. Subsequent volume ultrasonic treatment does not lead to significant changes in the corrosion rate, which in this case was 10 mm/year.

Background: Premature infants often experience frequent hypoxic episodes due to immaturity of respiratory control that may result in disturbances of gray and white matter development and long-term cognitive and behavioral abnormalities. We hypothesize that neonatal intermittent hypoxia alters cortical maturation of excitatory and inhibitory circuits that can be detected early with functional MRI., Methods: C57BL/6 mouse pups were exposed to an intermittent hypoxia (IH) regimen consisting of 12 to 20 daily hypoxic episodes of 5% oxygen exposure for 2 min at 37C from P3 to P7, followed by MRI at P12 and electrophysiological recordings in cortical slices and in vivo at several time points between P7 and P13. Behavioral tests were conducted at P41-P50 to assess animal activity and motor learning., Results: Adult mice after neonatal IH exhibited hyperactivity in open field test and impaired motor learning in complex wheel tasks. Patch clamp and evoked field potential electrophysiology revealed increased glutamatergic transmission accompanied by elevation of tonic inhibition. A decreased synaptic inhibitory drive was evidenced by miniature IPSC frequency on pyramidal cells, multi-unit activity recording in vivo in the motor cortex with selective GABA A receptor inhibitor picrotoxin injection, as well as by the decreased interneuron density at P13. There was also an increased tonic depolarizing effect of picrotoxin after IH on principal cells' membrane potential on patch clamp and direct current potential in extracellular recordings. The amplitude of low-frequency fluctuation on resting-state fMRI was larger, with a larger increase after picrotoxin injection in the IH group., Conclusions: Increased excitatory glutamatergic transmission, decreased numbers, and activity of inhibitory interneurons after neonatal IH may affect the maturation of connectivity in cortical networks, resulting in long-term cognitive and behavioral changes, including impaired motor learning and hyperactivity. Functional MRI reveals increased intrinsic connectivity in the sensorimotor cortex, suggesting neuronal dysfunction in cortical maturation after neonatal IH. The increased tonic inhibition, presumably due to tonic extrasynaptic GABA receptor drive, may be compensatory to the elevated excitatory glutamatergic transmission.