No abstract

Irradiation of iron with 5 MeV electrons is accompanied by the generation of point defects within small cascades, which changes the shape of the stage I resistivity recovery spectrum and stimulates the formation of di-interstitials that manifest their migration near the ID1 substage. The specific features of stage I recovery in concentrated Fe-Cr alloys are discussed in terms of mixed dumbbell formation, migration and trapping in configurations that include several chromium atoms. Resistivity values retained in the alloys at the end of stage I are well described by the trapping of Fe-Cr mixed dumbbells in chromium atom pairs.

A significant decrease of the cavitation threshold in aqueous suspensions of porous silicon nanoparticles (PSi NPs) with sizes about 100 nm as compared with pure water was observed for ultrasound irradiation (USI) with therapeutic frequency (0.88 MHz) and intensities (about 1 W/cm2). This effect is explained by porous morphology of PSi NPs, which promotes the nucleation of cavitation bubbles. In vitro experiments revealed a suppression of the proliferation of cancer cells with the introduced PSi NPs after exposure to USI related to the enhanced cavitation processes, which led to the cell destruction. The obtained results demonstrate that PSi NPs are prospective for applications as sonosensitizers in mild cancer therapy.

The resistivity recovery of pure and impurity-doped (0.2 - 1.5% Si, 0.15% C+N) concentrated ferritic Fe - Cr alloys after electron irradiation at 50 - 60 K has been investigated over the temperature range 110 - 390 K. A fine recovery spectrum structure consisting of five peaks has been observed over the range 135 - 230 K. Short-range ordering starts with the onset of vacancy long-range migration. Doping with both types of impurity suppresses the recovery spectrum structure over the range 160 - 220 K in a similar manner. Additional effects of impurity doping on the resistivity recovery caused by deviation from Matthiessen's rule have been analysed. A stage III peak is found at 210 K, and two peaks - at 175 K and 195 K - are interpreted as being due to the vacancy short-range migration. It is supposed that such a manifestation of short-range vacancy migration is due to a strong immobilization of self-interstitial atoms, and suppression of short-range and long-range defect annealing processes in stage I, according to a configuration-trapping mechanism similar to that of Ag - Zn alloys.

No abstract