The study of the applicability of a nano-polycrystalline diamond (NPD) as a lens material is presented. Two NPD plates with a diameter of 8 mm and a thickness of 0.1 and 1 mm were manufactured using the HPHT process. Coherence preservation properties of the NPD samples were checked using in-line phase-contrast imaging. Wide-Angle X-ray Scattering and Small Angle X-ray Scattering experiments were performed to examine the NPD scattering properties. Rotationally parabolic half-lens from a 100 μm thick NPD plate was manufactured using the maskless direct milling using a Zeiss CrossBeam 540 FIB-SEM system.

The spectral and spatial characteristics of the electroencephalograms recorded during the perception of written speech were studied. For the experimental study, four groups were formed, each containing 100 words: words with a positive emotional rating, words with a negative emotional rating, words with concrete meanings, and words with abstract meanings. A separate experiment was conducted for each group with the subjects. Words were represented by white text on a black background, each word was presented for 1000 ms, after the presentation of the stimulus there was a pause of 500 ms. Brain activity was recorded using an electroencephalograph with 19 leads, arranged according to the 10–20 scheme. For detailed quantitative analysis of this activity, method of functional tomography of the brain, based on electroencephalography data, was used. This method is based on the Fourier transform of multichannel encephalographic data and the localization of individual spectral components. The method makes it possible to single out and stably localize in space various spectral features of the brain activity studied in experiments on speech research. The frequency band from 8 to 30 Hz was analyzed; for all spectral components in this band, the inverse problem was solved in the approximation of an equivalent current dipole in a single-layer spherical conductor, without any restrictions on the position of the source. As a result, three-dimensional maps of activity were built - the functional structures of the brain. The presentation of these functional structures on magnetic resonance imaging allows one to study the frequency and spatial characteristics of responses to various speech stimuli.

An approach to the analysis of intracellular motion with nanosecond temporal resolution, based on the Mössbauer study of particles incorporated into a cell, has been developed. A possibility of applying magnetic nanoparticles as probes for studying in vitro the cytoplasm properties is analyzed. Two types of aqueous colloids of nanoparticles enriched with the 57Fe isotope are synthesized, and their cytotoxicity and biodegradation resistance under living cell conditions are investigated by an example of breast cancer cell line. It is found that the particles barely undergo any changes characteristic of biodegradation processes during their 120-h incubation in cells, although intracellular oxidation of divalent iron in the particle composition is observed. This result indicates possibility of using these particles for in vitro Mössbauer studies.

Magnetic responses of the brain to rhythmic visual stimulation are measured at frequencies of ~10 Hz using a 7-channel SQUID magnetoencephalograph. Despite the stationarity of the stimulation, the responses of the brain demonstrate the constant instability of the amplitude and spatial distribution of the magnetic field. The signal from the eyes is periodically redirected to different parts of the cortex, although the stimulation is always the same.

The nonstandard nature of intracellular motion is associated with a considerable content of macromolecules and is largely due to the phenomenon of abnormal diffusion. Features of the motion of nanoparticles in concentrated protein solutions that simulate cytoplasm are studied on a nanosecond time scale by means of Mössbauer spectroscopy. A comparative analysis is performed of the nano- and macro-viscosity of the media.

In ensembles of single-domain magnetic nanoparticles, a magnetic-dipole interaction between particles takes place. The controlled assembly of bulk magnetically ordered materials from such nanoparticles opens up wide prospects for the creation of new magnetic materials. One of the classical methods for obtaining an ordered ensemble of nanoparticles is their synthesis in a matrix of clay minerals such as montmorillonite. The interlayer space of the mineral acts as a nanoreactor with specific conditions for the particle synthesis. Intercalating iron polycations into montmorillonite, one can obtain well-ordered ensembles of magnetic nanoparticles. Magnetic nanocomposites created in this way have new properties and exhibit non-standard magnetic behavior, which cannot always be described in terms of classical concepts. We used the capabilities of Mössbauer relaxation spectroscopy to study magnetic nanocomposites in order to study the structural and magnetic features of nanoparticles formed in aluminosilicate layers “from the inside”. An analysis of the Mössbauer spectra revealed that ordered ensembles of antiferromagnetic α-Fe 2 O 3 nanoparticles formed between aluminosilicate layers of montmorillonite exhibited ferromagnetic behavior.

We demonstrate the capabilities of ion-beam lithography (IBL) for the manufacturing of the X-ray refractive micro-optics. For the first time with the help of IBL, the hardest of current materials - diamond - was milled, and microscale diamond half-lenses were produced. Lenses have a rotationally parabolic profile with radii of parabola apexes in the range from 3 to 10 mu m. As has been confirmed with SEM, the surface of produced lenses was free of low- and high-frequency modulations: figure errors of fabricated lenses were < 200 nm, while the surface roughness was estimated to be 30 nm. The optical performance of the lens was successfully tested at a third-generation synchrotron, where the lenses provided diffraction-limited focusing of X-ray radiation and demonstrated intensity profiles with Gaussian distributions at every measured longitudinal position (along the optical axis) downstream of the optics.

We demonstrate the capabilities of ion-beam lithography (IBL) for the manufacturing of the X-ray refractive micro-optics. With the help of IBL, the hardest of current materials - diamond - was milled, and microscale diamond lenses were produced. Lenses have a rotationally parabolic profile with radii of parabola apexes less than 5 µm. As has been confirmed with SEM and AFM, shape profile errors of fabricated lenses were<200 nm, while the surface roughness was estimated to be 50 nm. Single lenses were stacked in the CRL within one technological process with high alignment precision.

The line broadening in the Mössbauer spectra of nanoparticles in model colloids with known viscosity has been studied. Magnetite nanoparticles with average hydrodynamic sizes of 140 and 40 nm and a set of stable aqueous colloids based on them have been synthesized. The nanoparticles have been enriched in the 57 Fe isotope to compensate for the significant decrease in the Mössbauer effect probability in liquid media. Two series of temperature experiments have been carried out: in an aqueous colloid of nanoparticles with a 90-% glycerol content and on dehydrated samples of nanoparticles in the absence of Brownian motion. It is established that the Brownian motion of nanoparticles causes an additional broadening of Mössbauer lines, which is inversely proportional to the viscosity and nanoparticle size. It is demonstrated that Mössbauer spectroscopy allows one to separate the contributions of the Brownian motion and the Néel relaxation of magnetic nanoparticles. It is confirmed that the shape of Mössbauer spectrum and the probability of Mössbauer effect depend strongly on both the size of particles suspended in a liquid and the dynamic viscosity coefficient of the liquid.

Biodegradation of nanoparticles includes the destruction of a stabilizing coating and the accompanying change in interparticle interaction, as well as the direct destruction of the inorganic nuclei of particles. These processes lead to characteristic changes in the shape of the Mossbauer spectra of iron oxide nanoparticles. In this work, we investigated the in vitro biodegradation of Fe-57-based magnetic nanoparticles with the aid of Mossbauer spectroscopy. For this purpose, two types of magnetic nanoparticles enriched with the Fe-57 isotope were synthesized. Copolymer Pluronic F-127 and citric acid were used to stabilize nanoparticles in aqueous medium. Moreover, synthesized nanoparticles were analyzed by physicochemical methods and investigated for cytotoxicity. The study of magnetic nanoparticles biodegradation was performed on 4T1 cell culture (breast cancer). We measured Mossbauer spectra of nanoparticles incubated with 4T1 cells and spectra of control nanoparticle samples at different conditions. The analysis of spectra was carried out in the many-state relaxation model formalism. The study revealed that after 120-hours incubation of nanoparticles in cells, they did not undergo measurable changes typical of biodegradation processes. Nevertheless, we noted intense intracellular oxidation of ferrous iron of synthesized nanoparticles to the ferric phase. The results obtained indicate the possibility of using the obtained nanoparticles in Mossbauer in vitro studies.

Any existing method of visualization of magnetic nanoparticles in biological objects provides for imposing of an external magnetic field on the object under study. The field can considerably change the space distribution and properties of the nanomagnetic ensemble under study. In our work a SQUID-based magnetoencephalography device was used for the measurement of a magnetic noise generated by superparamagnetic nanoparticles based ferrofluid in the stationary standing vial without imposing of an external magnetic field. It was demonstrated that the ferrofluid generates spontaneous magnetic fields sufficient for its localization inside the experimental setup. Besides it was revealed that the spontaneous magnetic fields at certain frequencies have a strong spatial anisotropy. The detected effect can essentially increase the spatial resolution of the proposed method of visualization of magnetic nanoparticles in biological objects without using the external magnetic field.

Spectral and spatial characteristics of the encephalograms, registered while speech perception and production, are considered. Systematical bibliographical review is presented, including the articles studying the speech sources spectra and their location in the brain. Encephalography is selected as a basic experimental approach. Advantages of the magnetic encephalography, experimental difficulties and possible artifacts are noted. It is concluded that brain speech activity possesses a great variety of spectral and spatial features. The method of functional tomography based on magnetic encephalography data is proposed to quantitatively analyze this activity in detail. The method makes it possible to extract and precisely localize in space various spectral features of the brain activity studied in experiments on speech research.

A. Narikovich, P. Ershov, A. Lushnikov, A. Barannikov, I. Lyatun, M. Polikarpov, N. Klimova, I. Panormov, A. Sinitsyn, D. Zverev, I. Snigireva and *A. Snigirev 1 Immanuel Kant Baltic Federal University, Kaliningrad, Russian Federation 2 European Molecular Biology Laboratory, Hamburg unit, Hamburg, Germany 2 European Synchrotron Radiation Facility (ESRF), 38043, Grenoble, France Email: anatoly.snigirev@gmail.com

Using a previously developed procedure for predicting the parameters of betavoltaic cells, we carry out calculations for cells based on a radioactive film enriched with 63 Ni up to 50% and real silicon structures, namely, a Ni/ n –Si Schottky barrier and a p + – n diode. The procedure includes Monte Carlo calculation of the depth-dependent rate of the generation of β radiation by excess carriers and an experimental determination by SEM of the probability of their collection for specific structures. The need for such calculations is associated with the development of new possibilities of nickel enrichment with a radioactive isotope. We obtain achievable values of the short-circuit current, open-circuit voltage, filling factor, and cell power, which allows not only prediction of the parameters of such cells but also optimization of their structure. It is most expedient to use optimized p – n junctions in such cells.