ABSTRACT
Three-layer structures based on various multi-component films of III-V semiconductors heavily doped with Fe were grown using the pulsed laser sputtering of InSb, GaSb, InAs, GaAs and Fe solid targets. The structures comprising these InAsSb:Fe, InGaSb:Fe and InSb:Fe layers with Fe concentrations up to 24 at. % and separated by GaAs spacers were deposited on (001) i-GaAs substrates at 200 °C. Transmission electron microscopy showed that the structures have a rather high crystalline quality and do not contain secondary-phase inclusions. X-ray photoelectron spectroscopy investigations revealed a significant diffusion of Ga atoms from the GaAs regions into the InAsSb:Fe layers, which has led to the formation of an InGaAsSb:Fe compound with a Ga content up to 20 at. %. It has been found that the ferromagnetic properties of the InAsSb:Fe magnetic semiconductor improve with an increasing Sb:As ratio. It has been concluded that the indirect ferromagnetic exchange interaction between Fe atoms occurs predominantly via Sb atoms.
ABSTRACT
The ion-beam synthesis of Ga2O3 nanocrystals in dielectric matrices on silicon is a novel and promising way for creating nanomaterials based on gallium oxide. This research studies the regularities of changes, depending on the synthesis regimes used, in the chemical composition of ion-implanted SiO2/Si and Al2O3/Si samples. It has been shown that the formation of Ga-O chemical bonds occurs even in the absence of thermal annealing. We also found the conditions of ion irradiation and annealing at which the content of oxidized gallium in the stochiometric state of Ga2O3 exceeds 90%. For this structure, the formation of Ga2O3 nanocrystalline inclusions was confirmed by transmission electron microscopy.
ABSTRACT
Staphylococcus aureus induces the expression of VCAM-1, P- and E-selectins on the endothelial cells of the EA.hy926 cell line but, at the same time, causes the significant suppression of the force and work of adhesion between these receptors of endotheliocytes and the receptors of neutrophils in an experimental septicemia model. Adhesion contacts between the receptors of neutrophils and endotheliocytes are statistically significantly suppressed under non-opsonized and opsonized S. aureus treatment, which disrupts the initial stage of transendothelial migration of neutrophils-adhesion. Thus, S. aureus causes the arrest of neutrophils in the bloodstream in an experimental septicemia model.
ABSTRACT
A new method for creating nanomaterials based on gallium oxide by ion-beam synthesis of nanocrystals of this compound in a SiO2/Si dielectric matrix has been proposed. The influence of the order of irradiation with ions of phase-forming elements (gallium and oxygen) on the chemical composition of implanted layers is reported. The separation of gallium profiles in the elemental and oxidized states is shown, even in the absence of post-implantation annealing. As a result of annealing, blue photoluminescence, associated with the recombination of donor-acceptor pairs (DAP) in Ga2O3 nanocrystals, appears in the spectrum. The structural characterization by transmission electron microscopy confirms the formation of ß-Ga2O3 nanocrystals. The obtained results open up the possibility of using nanocrystalline gallium oxide inclusions in traditional CMOS technology.
ABSTRACT
We have developed a model for evaluating the integral intercellular interactions in the "endotheliocyte-neutrophil" system and have shown the high variability of adhesion contacts in different donors associated with different expression profiles of neutrophils. Two methods (forÑe spectroscopy-spectroscopy and scanning ion-conductance microscopy) showed a decrease in the rigidity of the membrane-cytoskeletal complex of neutrophils under the influence of Staphylococcus aureus 2879 M. Adding this strain to the "endotheliocyte-neutrophil" system caused a statistically significant decrease in the adhesion force and adhesion work, which indicates a change in the expression profile and physicochemical properties of membranes of both types of interacting cells (neutrophils and endotheliocytes).
Subject(s)
Endothelial Cells/cytology , Endothelial Cells/microbiology , Neutrophils/cytology , Neutrophils/microbiology , Staphylococcus aureus/physiology , Adult , Cell Adhesion , Cell Communication , Cell Line , Humans , Microscopy , Young AdultABSTRACT
In the process of performing their protective functions, neutrophils can form neutrophil extracellular traps (NETs), consisting of DNA in combination with enzymes and histones. The aim of the study was to determine the dynamics of the formation of NETs under the influence of opsonized Staphylococcus aureus and to determine the morphological features of their development in real time by atomic force microscopy. It was found that the maximum formation of NETs was observed after 3 hours of co-incubation of neutrophils and opsonized S. aureus. For the first time, the atomic force microscopy method revealed that, at first, large blocks of parallel DNA helices are formed, which then spread in waves, and only then their bifurcation and separation can be observed. Some of the strands formed are covered by a shell, which subsequently completely disappears. Enzymes and histones become clearly visible only after 140 to 150 minutes of observation. The DNA helixes move toward the opsonized S. aureus. After NET formation, the cell remains on the substrate only in the form of traces of focal adhesion. This, and the fact that the maximum amount of NETs is formed after 3 hours of co-incubation with opsonized S. aureus, suggests that the formation of NETs follows the classical mechanism. The study of the dynamics of formation and the microstructure of NETs makes it possible to estimate the time frame for the implementation of this protective mechanism of the human body when performing the compensatory inflammatory reaction.
