ABSTRACT
The spin physics of perovskite nanocrystals with confined electrons or holes is attracting increasing attention, both for fundamental studies and spintronic applications. Here, stable [Formula: see text] lead halide perovskite nanocrystals embedded in a fluorophosphate glass matrix are studied by time-resolved optical spectroscopy to unravel the coherent spin dynamics of holes and their interaction with nuclear spins of the 207Pb isotope. We demonstrate the spin mode locking effect provided by the synchronization of the Larmor precession of single hole spins in each nanocrystal in the ensemble that are excited periodically by a laser in an external magnetic field. The mode locking is enhanced by nuclei-induced frequency focusing. An ensemble spin dephasing time [Formula: see text] of a nanosecond and a single hole spin coherence time of T2 = 13 ns are measured. The developed theoretical model accounting for the mode locking and nuclear focusing for randomly oriented nanocrystals with perovskite band structure describes the experimental data very well.
ABSTRACT
We studied the effect of echinochrome A on the primary culture of pulmonary fibroblasts under normal conditions and under oxidative stress. Exposure to echinochrome A (100 µM, 6 h) did not affect the production of superoxide radical by fibroblasts, area of their nuclei, and number of nucleoli, but reduced the total area of nucleolar organizer regions against the background of stable proliferative activity of the culture. Two-hour oxidative stress induced by hydrogen peroxide solution (60 µM) increased the generation of superoxide radical, decreased DNA-synthetic activity of fibroblasts, area of fibroblast nuclei, and total area of nucleolar organizer regions. Preliminary administration of echinochrome A significantly attenuated the damaging effect of oxidative stress: the intensity of production of superoxide radicals decreased, DNA-synthetic activity and nucleus area of fibroblasts partially recovered; normalization of the total area of nucleoli was accompanied by an increase in their number.
Subject(s)
Antioxidants/pharmacology , Fibroblasts/drug effects , Naphthoquinones/pharmacology , Superoxides/antagonists & inhibitors , Animals , Animals, Newborn , Cell Nucleus/drug effects , Cell Nucleus/metabolism , Cell Nucleus/ultrastructure , Cell Proliferation/drug effects , Fibroblasts/metabolism , Fibroblasts/ultrastructure , Hydrogen Peroxide/antagonists & inhibitors , Hydrogen Peroxide/pharmacology , Lung/cytology , Lung/metabolism , Oxidative Stress/drug effects , Primary Cell Culture , Rats , Rats, Wistar , Superoxides/metabolismABSTRACT
The progression or the appearance of distant metastases in breast cancer (BC) is influenced by a variety of antitumor immune response suppression mechanisms. In this paper we study circulating dendritic cells (DC) and the suppressor cell populations in peripheral blood of breast cancer patients. The study of phenotypic and functional properties of DCs was performed in the samples of intact and TLR-stimulated whole blood from breast cancer patients and healthy women by multicolor flow cytometry. To determine the suppressor cell population among lymphocytes multicolor panel comprising markers CD 4, CD 25, CD 127, FoxP3 was used. It is showed that the formation of secondary foci of tumor growth in patients was accompanied by disturbances of the functional activity plasmocytoid DC and accumulation of cells with immunosuppressive functions.