Application of optical coherence tomography (OCT) in neurosurgery mostly includes the discrimination between intact and malignant tissues aimed at the detection of brain tumor margins. For particular ...tissue types, the existing approaches demonstrate low performance, which stimulates the further research for their improvement. The analysis of speckle patterns of brain OCT images is proposed to be taken into account for the discrimination between human brain glioma tissue and intact cortex and white matter. The speckle properties provide additional information of tissue structure, which could help to increase the efficiency of tissue differentiation. The wavelet analysis of OCT speckle patterns was applied to extract the power of local brightness fluctuations in speckle and its standard deviation. The speckle properties are analysed together with attenuation ones using a set of ex vivo brain tissue samples, including glioma of different grades. Various combinations of these features are considered to perform linear discriminant analysis for tissue differentiation. The results reveal that it is reasonable to include the local brightness fluctuations at first two wavelet decomposition levels in the analysis of OCT brain images aimed at neurosurgical diagnosis.
This work presents, for the first time, data on the possibility of synthesizing polyimide nanocomposite films based on track nuclear membranes and organosiloxane (polyhedral oligomeric ...silsesquioxanes) POSS structures. The synthesis of the nanocomposite films was carried out by filling the tracks of a polyimide membrane with POSS structures under hydrothermal conditions in a high-pressure reactor. The surface and mechanical characteristics of the developed nanocomposite films were studied, and the results of their resistance to the flow of oxygen plasma are presented. It was found that the introduction of POSS structures significantly increased the resistance of polyimide to the flow of oxygen plasma. The PI/POSS composite exhibited an insignificant change in weight, the weight loss reached 0.92 ± 0.05 mg/cm2 in 24 h after the start of the experiment, which is almost two orders of magnitude lower than that of the polyimide film.
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•PI/POSS nanocomposite films obtained in a high-pressure reactor.•POSS structures are located in the tracks of the PI nuclear membrane.•The effect of oxygen plasma on PI and PI/POSS was investigated.•The erosion yield of PI – 3.05 × 10−24 cm3/atom, PI/POSS – 0.15 × 10−24 cm3/atom3.•Mechanical performance of PI/POSS nanocomposite films after oxygen plasma increased.
Squalene-based adjuvant compositions that can provide effective induction of specific humoral immune response have been developed. Recombinant receptor-binding domain (RBD) of surface S-protein of ...SARS-CoV-2 was used to evaluate the properties of the composition. Immunization of mice with the developed squalene-based compositions in combination with RBD allows obtaining high titers of specific antibodies: from 10
5
to 2×10
6
. The blood sera from immunized mice exhibit neutralizing activity against SARS-CoV-2 Delta variant (B.1.617.2) with a titer up to 1:2000.
Detailed study of the luminescence of multiple brown CVD diamonds was performed. It has been found that the well-known optical center with zero-phonon line at 468 nm is a characteristic of brown ...color. It has been found that the defects responsible for 468 nm center are located within brown striations suggesting close relation of the 468 nm center and the vacancy clusters. Simultaneous reduction of the intensity of 468 nm center and brown color during annealing support the assumption of their close relation. Identical spectroscopic parameters of the 468 nm center and the radiation center with ZPL at 492 nm suggest that the former relates to an intrinsic defect probably containing vacancies. The distribution of intensity of the 468 nm center in some brown diamonds follows the distribution of the NV− center while being opposite to that of the NV0 center and the dislocation-related A-band. This observation suggests the negative charge state of the 468 nm center. Due to its high luminescence efficiency, the 468 nm center can be used as a highly sensitive indicator of the traces of vacancy clusters. We found that the 468 nm center is detected practically in every as-grown CVD diamond including colorless CVD diamonds of high structural perfection and high purity.
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•468 nm center is the luminescence signature of brown CVD diamonds.•468 nm center is assigned to negatively-charged intrinsic defects located at vacancy clusters in CVD diamonds.•468 nm luminescence can be used for detection of trace concentrations of vacancy clusters in CVD diamonds.
A device for controlling a two-winding polarized electromagnet is considered, and its disadvantages are noted. A circuit for the control of a single-winding polarized electromagnet is proposed in ...which the disadvantages of the existing control circuit are eliminated. Transient processes of charge/discharge of a capacitor to ensure actuation and reset of a polarized electromagnet are considered. The operability of the proposed circuit based on a composite transistor has been experimentally confirmed.
High perfect single crystal of Li2W0·95Mo0·05O4, which is one of the perspective materials to search rare events, has been grown by a low-temperature-gradient Czochralski technique with weight ...control. Thermodynamics of obtained single crystal with emphasis on such basic characteristics as stabilization energy, lattice enthalpy, and standard formation enthalpy was studied using reaction calorimetry. It has been shown that dependences of lattice enthalpies and standard formation enthalpies on the molybdenum content (x) for Li2W1-xMoxO4 are linear. It has been established that stabilization energy of single crystal Li2W0·95Mo0·05O4 is several times more than stabilization energies of single crystals ZnMoO4 and CdWO4. The correlation was found between lattice energy of Li2W1-xMoxO4 compounds and luminescence wavelength. It was shown that for system Li2MoO4–Li2WO4, the luminescence wavelength is increased with increasing the lattice energy. The hypothesis to explain the correlation was formulated. The heat capacities for Li2MoO4 single crystal have been determined by DSC calorimetry in the temperature range of 303–819 K. No anomalies in heat capacities associated with phase transitions were found.
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•High perfect single crystal of Li2W0·95Mo0·05O4 has been grown.•Linear dependences of lattice enthalpies and formation enthalpies on x for Li2W1-xMoxO4 have been found.•Li2W0·95Mo0·05O4 stabilization energy has been found several times more than ZnMoO4 and CdWO4 ones.•Luminescence wavelength in Li2MoO4–Li2WO4 has been found increased with increasing the lattice energy.•Heat capacities for Li2MoO4 single crystal have been determined in the temperature range of 303–819 K.
Round ingots 110 mm in diameter and cold-rolled sheets 2 mm in thickness, which were made of experimental Al–Mg–Sc alloys containing with different scandium content (0.07, 0.20 wt %), have been ...studied. Transmission electron microscopy and thermodynamic simulation have been used to investigate the peculiarities of the structural-phase state of the material. A reduction in scandium content from 0.20 to 0.07% has been found to result in a twofold increase in the grain size in ingots, a 46% drop in hardening of ingots after homogenization, and a 10–20% decrease in the strength of annealed sheets, which has been caused by a smaller amount of the key phase, Al
3
(Sc, Zr). A good level of strength characteristics of experimental annealed sheets made of alloy with low scandium content 0.07 wt % (σ
u
> 400 MPa, σ
0.2
> 300 MPa) has been achieved and it is higher than that of the traditional AMg6 alloy (σ
u
> 350 MPa, σ
0.2
> 150 MPa).
Single crystal CVD diamond has been grown on (100)-oriented CVD diamond seed in six layers to a total thickness of 4.3 mm, each layer being grown in gas with increasing concentration of nitrogen. The ...nitrogen doping efficiency, distribution of color and internal stress have been studied by SIMS, optical absorption, Raman spectroscopy and birefringence imaging. It is shown that nitrogen doping is very non-uniform. This non-uniformity is explained by the terraced growth of CVD diamond. The color of the nitrogen-doped diamond is grayish-brown with color intensity gradually increasing with nitrogen concentration. The absorption spectra are analyzed in terms of two continua representing brown and gray color components. The brown absorption continuum exponentially rises towards short wavelength. Its intensity correlates with the concentration of nitrogen C-defects. Small vacancy clusters are discussed as the defects responsible for the brown absorption continuum. The gray absorption continuum has weak and almost linear spectral dependence through the near infrared and visible spectral range. It is ascribed to carbon nanoclusters which may form in plasma and get trapped into growing diamond. It is suggested that Mie light scattering on the carbon nanoclusters substantially contributes to the gray absorption continuum and determines its weak spectral dependence. A Raman line at a wavenumber of 1550 cm−1 is described as a characteristic feature of the carbon nanoclusters. The striation pattern of brown/gray color follows the pattern of anomalous birefringence suggesting that the vacancy clusters and carbon inclusions are the main cause of internal stress in CVD diamond. A conclusion is made that high perfection of seed surface at microscale is not a required condition for growth of low-stress, low-inclusion single crystal CVD diamond. Crystallographic order at macroscale is more important requirement for the seed surface.
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Results of structural studies of aluminum alloys of the Al – Si – Mg – (Cu) system obtained by selective laser melting are analyzed and systematized. The effect of heat treatment on the structural ...and phase condition of the alloys is investigated with the use of thermodynamic simulation and transmission electron microscopy. Comparative analysis of mechanical properties of the alloys in different states provided by different heat treatments is performed.
Differences in the developmental origin and relative proportions of biochemically distinct classes of cortical neurons have been found between rodents and primates. In addition, species differences ...in the properties of certain cell types, such as neurogliaform cells, have also been reported. Consequently, in this study we compared the anatomical and physiological properties of parvalbumin (PV)-positive basket interneurons in the prefrontal cortex of macaque monkeys and rats. The somal size, total dendritic length, and horizontal and vertical spans of the axonal arbor were similar in monkeys and rats. Physiologically, PV basket cells could be identified as fast-spiking interneurons in both species, based on their short spike and high-frequency firing without adaptation. However, important interspecies differences in the intrinsic physiological properties were found. In monkeys, basket cells had a higher input resistance and a lower firing threshold, and they generated more spikes at near-threshold current intensities than those in rats. Thus monkey basket cells appeared to be more excitable. In addition, rat basket cells consistently fired the first spike with a substantial delay and generated spike trains interrupted by quiescent periods more often than monkey basket cells. The frequency of miniature excitatory postsynaptic potentials in basket cells was considerably higher in rats than that in monkeys. These differences between rats and monkeys in the electrophysiological properties of PV-positive basket cells may contribute to the differential patterns of neuronal activation observed in rats and monkeys performing working-memory tasks.
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