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The possibility of controlling the magnetic properties of multilayered periodical structures with perpendicular magnetic anisotropy, which are based on cobalt and platinum films, have been studied. The multilayered films composed by layers with a thickness of 0.5–1.0 nm were subjected to two types of actions: vacuum annealing at different temperatures and irradiation by helium ion beams. Transmission electron microscopy has shown that the irradiation by He+ ions with energy of 30 keV leads to material mixing in the layers since at vacuum annealing the layered structure of films is kept. In this case, as a result of thermal annealing, the coercive force of the structure increases significantly, and upon irradiation with helium ions, the coercivity of the films decreases to a change in the type of anisotropy from perpendicular to “easy plane” anisotropy.

The influence of hydrogen plasma treatment on electrical and optical properties of the vertical GaN nanowires (NWs)/Si heterostructures synthesized via plasma assisted molecular beam epitaxy is studied. The effect of the treatment is thoroughly studied via variation of the passivation duration. Photoluminescence (PL) investigation demonstrates that the passivation affects the doping of the GaN NWs. The samples were processed as photodiodes with top transparent electrode to obtain detailed information about the n-GaN NWs/p-Si heterointerface under illumination. Electron beam induced current (EBIC) measurements demonstrated the absence of the potential barriers between active parts of the diode and the contacts, indicating ohmic behavior of the latter. I-V characteristics obtained in the dark and under illumination show that hydrogen can effectively passivate the recombination centers at the GaN NWs/Si heterointerface. The optimum passivation duration providing improved electrical properties is found to be 10 minutes within taken passivation regimes. It is demonstrated that the longer treatment causes degradation of the electrical properties. The discovered phenomenon is discussed in details.

Platelet concentrate is used to restore and maintain hemostasis in patients with a reduced number or activity of platelets. Platelet concentrate changes its properties when stored, which leads to a weakening of the therapeutic effect, as well as the occurrence of transfusion side effects. One of the processes that alter platelet concentrates during storage is the secretion of several types of membrane vesicles. Despite the fact that platelet-derived membrane vesicles affect homeostasis and transmit signals of intercellular communication, mechanisms of their formation, features of regulatory activity and molecular composition are still poorly understood. In this paper, the results of analysis of CD42b and CD9 membrane proteins expression in platelets and platelet-derived membrane vesicles during platelet-concentrate storage are presented. Populations of membrane vesicles of different sizes were isolated from the platelet concentrates and characterized. Aggregation and morphological alteration of platelets are observed during storage; the protein composition of platelets, as well as membrane vesicles, changes, and there is a significant increase in the levels of CD42b and CD9 proteins in fractions of membrane vesicles. The results obtained indicate that platelet concentrates contain different populations of membrane vesicles, the molecular composition of which varies during storage.

Extracellular vesicles secreted by cells represent an almost spherical membrane structures enriched with biological molecules of different types. The number and molecular composition of these structures depend on both the physiological state of an organism and underlying diseases. Despite extracellular vesicles playing an important role in intercellular communication and being potential biomarkers of pathological processes, the mechanisms of their formation, their functions, and their morphological characteristics are poorly studied. Low-voltage scanning electron microscopy is a promising method for studying extracellular vesicles, since it does not need a layer of conductive covering and, consequently, permits morphological details of studied objects to be vizualized at a high resolution in a nanometer range. The results of investigation of the morphology and sizes of objects in blood-plasma fractions by low-voltage scanning electron microscopy are presented in this study.

The report presents the results of an experimental study on the observation of inhomogeneous magnetic distributions by the Lorentz electron microscopy method in Permalloy nanodisks and Co/Pt multilayer films. Magnetic nanodisk systems were used to calibrate the magnetic field in the objective lens of the microscope LIBRA 200MC. The magnetic properties of Co/Pt multilayer films were locally modified by irradiation with a sharply focused ion beam in a scanning helium ion microscope. As a result of such irradiation, periodic lattices of inhomogeneous magnetization distributions were formed in continuous films, the spin configuration of which depends on the dose of local irradiation.

The effect of hydrogen plasma treatment on the electrical and optical properties of GaN NWs/Si based vertical hetero structures synthesized by the method of plasma molecular beam epitaxy is studied. The effect of treatment has been carefully studied by variation of the passivation duration. Measurements of the electron beam-induced current (EBIC) technique showed the absence of potential barriers between the active parts of the diode and the contacts, which indicates the ohmic behavior of the latter. The current - voltage characteristics show that hydrogen can efficiently passivate recombination centers at the GaN NWs/Si heterointerface. It is established that the optimal passivation duration, providing improved electrical properties, is 10 minutes in the adopted passivation modes. It is shown that a longer treatment causes a deterioration in electrical properties.

Extracellular vesicles are subspherical membranous structures secreted by cells and enriched with different types of biological molecules. The number and the molecular content of these structures depend on pathological conditions and the physiological state of the organism. Extracellular vesicles play an important role in intercellular communication and represent potential disease biomarkers. However, mechanisms of formation, functions and morphological characteristics of extracellular vesicles are still studied insufficiently. Low voltage scanning electron microscopy is a promising method to investigate extracellular vesicles, since it does not require conductive coating and therefore enables a high-resolution visualization of morphological details of nanosized objects. This paper presents the results of low voltage scanning electron microscopy study of morphology and size of objects from blood plasma fractions.

Data for the study of various contrasts in the methods of scanning electron and ion microscopy with the energy filtration of signals from secondary and reflected electrons are presented. A model of the formation of contrast by secondary electrons in a helium scanning electron microscope is formulated. The possibility of contrast amplification via energy filtration in a helium ion microscope as well as the chance of recording reflected ions by means of secondary electron detection is demonstrated. The recorded data for the material contrast in low-voltage electron microscopy at various acceleration voltages and different modes of energy filtration are given. The possibility of enhancing or reducing material contrast by means of energy filtration is shown.

In this work we have investigated the exciton reflectance spectra of a high quality heterostructure with a GaAs/AlGaAs quantum well in a transverse magnetic field (Voigt geometry). It has been shown that application of the magnetic field leads to a decrease of energy distance between spectral features related to the excitonlike polariton modes. This effect has been treated as the magneto-induced increase of the exciton mass. We have shown that the hydrogenlike and diamagnetic exciton models are insufficient to describe the exciton behavior in the intermediate magnetic fields studied. Considering the symmetry of the problem, we have developed a phenomenological model which adequately describes the experimental data.

Visual art is an integral part of human life, which, like a mirror, reflects the lifestyle and capabilities of a generation. Moreover, each epoch contributes to the development of artistic expression techniques. In this article, we discuss three novel approaches to visual art and design from the point of view of modern photonics and laser technology. Laser methods of metal coloring are considered regarding their physical nature, and their ample opportunities for the creation of different artworks are demonstrated.

Cathodoluminescence (CL), electron beam current (EBIC) and transmission electron microscopy (TEM) techniques have been applied to investigate recombination properties and structure of freshly introduced dislocations in low-ohmic GaN crystals. It was confirmed that the only a-screw dislocations exhibited an intense characteristic dislocation-related luminescence (DRL) which persisted up to room temperature and was red-shifted by about 0.3 eV with respect to the band gap energy not only in HVPE but also in MOCVD grown samples. EBIC contrast of the dislocations was found to be temperature independent indicating that the dislocation-related recombination level is situated below 200 meV with respect of conduction band minimum. With the increasing of the magnification of the dislocation TEM cross-sectional images they were found to disappear, probably, due to the recombination enhanced dislocation glide (REDG) under electron beam exposure which was immediately observed in CL investigations on a large scale. The stacking fault ribbon in the core of dissociated a-screw dislocation which form a quantum well for electrons was proposed to play an important role both in DRL spectrum formation and in REDG.

We report here on the possibility of a local modification of Co/Pt multilayered magnetic films by focused ion beam irradiation. The changes of structural and magnetic properties are experimentally investigated as a function of irradiation fluence. The method is used to form lateral structures with the periods up to 100nm. The magnetic force microscopy accompanied by Hall effect measurements of the structure indicate the formation of magnetic skyrmion lattices in the absence of Dzyaloshinskii-Moriya interaction.

We experimentally compared the shapes and sizes of isolated domains created by the focused ion beam irradiation in the lithium niobate crystals doped by MgO with polar surface covered by dielectric (resist) layer and those with free surface. We attributed the larger sizes of isolated domains in the samples covered by the resist layer to ion localization in the resist. We revealed a change in the domain shape as a function of increasing dose and explained it in terms of kinetic approach taking into account the modification of the surface layers by ion irradiation. We applied the obtained knowledge for 1D and 2D periodical poling using ion beam. Finally, we created the 2D square 1-μm-period array of isolated domains with radius about 300 nm and maximal depth of all domains in the array up to 100 μm as well as the 1D pattern of through stripe domains with 2-μm-period in 1-mm-thick wafer.