We study the possibility to stabilize the gyrotron frequency under the influence of a wave reflected from a remote output window during the competition of the operating mode with two neighboring ...modes, which have frequencies equally spaced from the frequency of the operating mode. The window is assumed to reflect radiation at the frequency of the operating mode and be transparent for the neighboring modes. The influence of the shift of the reflector within the limits of several wavelengths on the frequency stabilization is considered. The fluctuations in the frequency and phase of the radiation, which are caused by low-frequency technical noises of the accelerating voltage of the electron beam, in a stand-alone gyrotron and a gyrotron with a reflection are compared. The calculations were performed for the megawatt gyrotron with a frequency of 170 GHz and the operating TE mode, which was developed at the Institute of Applied Physics of the Russian Academy of Sciences (IAP).
A systematic study has been performed for the effect of nonionic surfactants (NSs), i.e., ethoxylated higher fatty alcohols with different ethoxylation degrees, on the ultrasonic dispersion of carbon ...nanotubes in aqueous solutions and on the colloid-chemical properties of the resulting dispersions, namely, their optical density and the sizes and electrokinetic potentials of the particles in the colloidal systems. A non-linear dependence of the characteristics of dispersions on the ethoxylation degree has been revealed. This dependence is associated with structural transformations in NS molecules. The most efficient ethoxylation degree and concentration of nonionic surfactants in a solution, which have the highest disaggregating and stabilizing effects upon the preparation of carbon nanotube (CNT) dispersions, have been determined. The influence of the ethoxylation degree of the ethoxylated higher fatty alcohols on the electrokinetic properties of CNT dispersions has been revealed. It has been shown that carbon nanotube dispersions can be used to modify the rheological and electrical properties of gel systems based on rarely crosslinked poly(acrylic acid). The effects of NSs and CNTs on the viscosity, shear yield stress, consistency index, mechanical stability, relaxation time, and viscous flow activation energy of the polymer gels have been studied. It has been shown that the incorporation of nanotubes increases the electrical conductivity of the gels. The ultrastructure of the gel samples has been studied by transmission electron microscopy.
The paper is devoted to investigation of SO2 emissions in atmospheric air using the OMI space monitoring database for the northern territories of the Krasnoyarsk region in Russia. The highest ...concentration of SO2 emissions was recorded in April 2019 - 41.2 DU, and the smallest in July 2019 - 0.5 DU. Actual air pollution in populated areas for the northern territories of the Krasnoyarsk Territory corresponds to a high degree of pollution, except for 2013 and 2014 when it was a moderate degree of pollution.
General patterns of localized plastic flow development are described at linear work hardening stages of nineteen metals. Correlations between the position of the element in the periodic table of ...elements and the parameters of the autowave localized plastic flow have been established and discussed. The observed correlations indicate the existence of dependences of the localized plastic flow in a deformable medium on the lattice parameters of the elements and their electronic structures.
To improve technique of intraoperative ultrasound-assisted microsurgery of spinal tumors.
There were 68 patients with 70 spinal tumors who underwent intraoperative ultrasound-assisted resection ...between 2007 and 2018. Age of patients varied from 21 to 80 (mean 48.5±14.3). Intradural tumors were diagnosed in 54 (79.4%) patients (of them intramedullary in 16 (23.5%) and extramedullary in 38 (55.9%) cases). Fourteen patients (20.6%) had extradural tumors. Intraoperative ultrasound was used to determine localization, margins and structure of tumors, interrelations with neural structures, zones of dura opening and myelotomy. We also assessed quality of resection and spinal decompression.
In surgery of spinal tumors, intraoperative ultrasound allows to localize the tumor with 95.3% sensitivity, determine the character of its growth, shape, size and internal structure. One can also differentiate the margins of neoplasm, control accuracy of approach, select the optimal zone for dura opening and myelotomy, objectively assess spinal cord and nerve roots decompression in real-time mode. Quality of intraoperative ultrasonography images is comparable to preoperative MRI, and even exceed resolution of MR scans in some cases.
In our study, intraoperative ultrasound has proven to be a method complementing preoperative CT and MRI. This approach provides additional data in real-time mode to form a complete picture of surgical area, increase accuracy of manipulations and reduce surgical trauma.
Abstract
We have measured the absolute intensities of the spectral lines of Kr, Ar, and O ions (CO
2
gas), which are of interest for reflectometry, microscopy, and lithography in the wavelength range ...of 10 – 18 nm. We have used pulsed excitation by an Nd : YAG laser with an output wavelength
λ
= 1064 nm, a pulse energy of 0.8 J, a pulse duration of 5.2 ns and a pulse repetition rate of 10 Hz. The targets are formed during gas outflow through a pulsed supersonic conical nozzle for an inlet gas pressure of 3.5 bar. A spectrometer based on X-ray multilayer mirrors and its calibration procedure are described in detail. The absolute intensities of the spectral lines of Kr IX (
λ
= 11.5 nm; number of photons:
N
= 9.3 × 10
12
photons pulse
−1
), Ar VIII (
λ
= 13.84 nm,
N
= 3 × 10
12
photons pulse
−1
), and O VI (
λ
= 12.98 nm,
N
= 5.17 × 10
12
photons pulse
−1
). The results are compared with the data obtained for Xe ions under the same experimental conditions at the same wavelengths.
The localized plasticity development was studied for a wide range of pure metals and alloys in single-crystal and polycrystalline state as well as nonmetallic materials, alkaline halide crystals, ...ceramics and rocks. Using photographic and digital versions of speckle photography, the localization of plastic flow in the test samples was investigated on specially designed units having high spatial and temporal resolution. According to the analysis given here, the different stages of plastic flow are related both qualitatively and quantitatively.
Autowave process of plastic flow localization Zuev, L B; Barannikova, S A; Zharmukhambetova, A M
Journal of physics. Conference series,
04/2020, Letnik:
1527, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The localized plasticity development was studied for a wide range of pure metals and alloys in single-crystal and polycrystalline state as well as nonmetallic materials, alkaline halide crystals, ...ceramics and rocks. Using photographic and digital versions of speckle photography, the localization of plastic flow in the test samples was investigated on specially designed units having high spatial and temporal resolution. According to the analysis given here, the different stages of plastic flow are related both qualitatively and quantitatively.
The effect of binding of divalent metal cations (Ca2+, Cu2+, Mg2+, Mn2+, Zn2+) on the kinetics of fibril formation of bovine α-lactalbumin at acidic conditions is considered. The kinetic parameters ...of the process were determined using a thioflavin T fluorescence assay. The DSC thermograms of bovine α-lactalbumin in the presence and absence of cations were recorded. The duration of the lag period correlates with the changes in the thermal stability of the molten globule of the protein in the presence of cations. The final thioflavin T fluorescence intensity after formation of the mature fibrils decreases under the influence of calcium ions which strongly bind to the monomeric protein, and increases in solutions containing copper and especially zinc. These ions seem to accelerate secondary nucleation processes and change the fibril morphology, which was confirmed by atomic force microscopy imaging.The effect of binding of divalent metal cations (Ca2+, Cu2+, Mg2+, Mn2+, Zn2+) on the kinetics of fibril formation of bovine α-lactalbumin at acidic conditions is considered. The kinetic parameters of the process were determined using a thioflavin T fluorescence assay. The DSC thermograms of bovine α-lactalbumin in the presence and absence of cations were recorded. The duration of the lag period correlates with the changes in the thermal stability of the molten globule of the protein in the presence of cations. The final thioflavin T fluorescence intensity after formation of the mature fibrils decreases under the influence of calcium ions which strongly bind to the monomeric protein, and increases in solutions containing copper and especially zinc. These ions seem to accelerate secondary nucleation processes and change the fibril morphology, which was confirmed by atomic force microscopy imaging.
Vibrating kinetics of the Luders front Zuev, L B; Barannikova, S A; Zharmukhambetova, A M
Journal of physics. Conference series,
01/2020, Letnik:
1431, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The regularities of the inhomogeneous plastic deformation such as Lüders bands are considered at the yield plateau. It has been established that the Luder front has stick-slip motion under these ...conditions. Such a character of motion at the deformation front is associated with the inhomogeneous distributions of the components of the plastic distortion tensor. A plausible estimate of the oscillation frequency was obtained during the development of the Lüders front. The estimation of the spatial period (the length of the autowave of localized deformation) also corresponds to reality.
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