Tatiana Borodina

Shock metamorphism of plagioclase and amphibole (Experimental data)

The shock metamorphism of plagioclase and amphibole of various chemical compositions from amphibolite and granulite facies schists was studied in experiments with shock wave loading of samples in steel recovery ampoules of plane geometry. A maximum shock pressure was reached after a few circulations of waves in the sample (stepwise shock wave compression) and varied within 26–52 GPa. The recovered samples were examined by the methods of scanning electron microscopy and microprobe and X-ray phase analysis. It is established that an increase in the F, Ti, and K concentrations in amphibole and a decrease in the Ca concentration in plagioclase make these minerals more stable with respect to shock waves. It is shown that the migration of some chemical elements, starting already at the solid phase stage of transformation in plagioclase and amphibole, is intensified at the stage of melting. It is established that isotropization of plagioclase occurs through two different mechanisms. At relatively low pressures, it is caused by the fragmentation of substance at the microlevel and is accompanied by the formation of maskelynite, a typical mineral of meteorites and astrobleme rocks. At higher pressures, isotropization is associated with melting-induced amorphization.

Shock metamorphism of the graphite quasimonocrystal

Abstract Micro structure examination of graphite quasimonocrystal recovered after dynamic loading to pressure of 35-45 GPa was carried out. Only a small amount of cubic diamond and recrystalized graphite was detected. Most of the graphite (∼80 vol.%) remained in initial high orientation, but transformed to fine, grained phase with crystalite size 0.1-1 microns. Relaxation time of the transformation (∼ 10 ns) and the degree of the transformation (∼ 70-80 vol.%) were determined by means of measurements of the electrical resistivity during loading up to 26 GPa and following computer simulation of the results. We proposed that two simultaneous processes take place at pressures higher than 20 GPa: i) relatively slow diffusive graphite to diamond transformation localized in the zones with defect structure: ii) highly oriented graphite transforms to a diamond like phase with density of about 3.2 g/cm3 at zero pressure. This, transformation has fast, martensitic kinetics and is reversible.

Shock response and structure of yttria-doped tetragonal zirconia

The ceramics on the basis of the partially stabilized zirconia was produced, and some characteristics of the ceramics, such as density, bending strength, crack resistance, Rockwell hardness, microhardness, porosity, etc. were determined. Microstructure and phase composition of the ceramics as well as the phase transformations under mechanical fracture were studied. Hugoniot elastic limit and spall strength of the ceramic specimens were measured.

A novel formulation of zolpidem for direct nose-to-brain delivery: synthesis, encapsulation and intranasal administration to mice

Anxiolytic drug zolpidem was incorporated into the microcontainers based on mesoporous calcium carbonate particles modified by diethylaminoethyl‐dextran/hyaluronic acid shell. The release of zolpidem in saline solution and in polymer film modelling nasal mucosa was investigated. The anxiolytic effect of zolpidem upon intranasal administration of microcontainers and free medicine was determined by in vivo experiments on mice.

PHASE TRANSITIONS OF C70 FULLERITE UNDER STEP‐LIKE SHOCK COMPRESSION

Shock‐induced phase transitions of C70 fullerite with hexagonal close‐packed structure were experimentally studied with use of recovery assemblies of planar geometry at pressures 8 to 36 GPa. It was found that C70 fullerite undergoes a series of polymorphic transitions in conditions of step‐like shock compression. Hexagonal close‐packed structure of C70 fullerite remained practically unchanged at shock pressure 8 GPa. Shock‐induced transformation of the hexagonal structure into face centered cubic structure was fixed at pressures in the range 8 to 23.5 GPa. Depth of this transformation was increasing with growth of shock pressure. With further growth of shock pressure the destruction of C70 molecules occurs. This destruction is accompanying with a formation of graphite‐like carbon.