It is considered that asexual reproduction of organisms should lead to accumulation of harmful mutations in a series of successive generations (the so-called “Muller’s ratchet”). Accordingly, ...effective mechanisms for “nulling” this effect should exist in the life cycle of obligate agamic protists. According to one hypothesis, a so-called “cyclic polyploidy” (or agamic ploidy cycle) can act as such a mechanism. Lobose amoebae
Amoeba proteus
and closely related species are obligate agamic organisms. The karyological analysis that we conducted, as well as a detailed study of the cell cycle of
A. proteus
and
A. borokensis
using optical tomography, allow us to conclude that these organisms have a special kind of cyclic polyploidy. The euploid state of the nucleus takes a completely insignificant period of time relative to the duration of the entire nuclear cycle of these amoebae, the stages of meta- and telophase of mitosis, whereas the rest time of the cycle is associated with the aneuploid state of the nucleus.
The present paper describes the properties of a silicon blade-type cathode with high technological reproducibility. The emission characteristics were obtained using a modern computerized method for ...studying field emission cathodes in a non-destructive pulsed mode with a flat anode. The technique includes an assessment of the emission current stability, an estimate of the magnitude of the effective parameters of the cathode (field enhancement and emission area) and the degree of their fluctuations over time. A numerical analysis of the glow patterns of the field emission projector was also performed, representing of the distribution of the current load along the edge of blade-type field emitter.
Some properties of metamaterials with a negative Poisson’s ratio (auxetics) have been studied experimentally when punched along the normal by a rigid spherical impactor. Samples of a metamaterial ...with a chiral structure (hexachirals honeycomb) are made of e-PLA plastic using a 3D printer. In experiments, a deviation of the direction of movement of the impactor after leaving the punched sample from the approach direction (normal to the side surface) is observed. The dependence of the impactor projection direction on the orientation of the elements of chiral symmetry of the samples is established. A FE model for calculating the penetration of a chiral structure has been developed. Numerical results are presented and their agreement with experimental data is noted.
The karyotype of
Amoeba borokensis
was studied for the first time. At the metaphase of mitosis, this species has a haploid set of chromosomes (
n
= 27). This is exactly half of the diploid karyotype ...in
Amoeba proteus
(strain B). At first glance, it confirms the idea that has recently appeared that one species arises from another via multiple changes in chromosome number. However, comparative cytogenetic analysis revealed that four orthologous chromosomes from haploid sets of these two species were not distinguished by the pattern of DAPI-stained bands. It shows that the genetic distance between
A. proteus
and
A. borokensis
is higher than was believed earlier and these two species have diverged from each other. Analysis of data on the life cycles of
A. proteus
and
A. borokensis
shows that a kind of so-called “cyclic polyploidy” takes place in “
proteus
-like” amoebae. “Cyclic polyploidy” has recently been considered as an alternative to the sexual process for genetic recombination in agamic protists from different macrotaxons.
The modernization program of the Moscow Oil Refinery includes a proposal to create an Advanced Oil Refining Complex that comprises the construction of flexicoking processing units and a power ...generation unit operating with flexigas, a low-calorific gas formed in the process of flexicoking. This will make it possible to reduce the demand for steam and electric power from external networks. An analysis of the currently functioning and future demands of the Moscow Oil Refinery for energy resources and estimation of existing energy sources for the plant is performed, requirements imposed on the power generation unit are determined, current flexigas firing technologies are reviewed, the choice of an optimal variant configuration of the power generation unit is evaluated, and the principal technical decisions for the equipment of the power generation unit are presented.
Karyotyping of Amoeba proteus Demin, S. Yu; Berdieva, M. A.; Podlipaeva, Yu. I. ...
Cell and tissue biology,
07/2017, Volume:
11, Issue:
4
Journal Article
Peer reviewed
In this paper, we have developed a method to prepare spreads of mitotic chromosomes of
Amoeba proteus
and described the process of
Amoeba proteus
karyotyping. This protocol allows obtaining spread ...chromosomes with a characteristic pattern of chromomeres on individual chromosomes. It is shown that, in the metaphase of mitosis, amoebas of strain B (one of the type strains of
A. proteus
in the Amoebae Cultures Collection of the Institute of Cytology, Russian Academy of Sciences) contain 27 pairs of chromosomes. It is established that the pattern of chromomeres is a chromosome-specific feature. A typical karyogram and image bank of DAPI- and YoYo1-banded individual chromosomes of
A. proteus
, strain B composed of five different spreads of mitotic cells are presented.
Experimental melts using barium-based modifiers produced by OOO NPP Tekhnologiya are undertaken at OAO Vyksunskii Metallurgicheskii Zavod, under the supervision of specialists from Baikov Institute ...of Metallurgy and OOO NPP Tekhnologiya. Such modifiers improve the quality of the wheel steel produced. Modification by Insteel® 1.3 alloys reduces the content of nonmetallic inclusions in the steel and reduces the rejection rate of the corresponding railroad wheels.
30 kV Pulse Diode Stack Based on 4H-SiC Ivanov, Boris V.; Demin, Yuri S.; Sergushichev, K.A. ...
Materials science forum,
06/2018, Volume:
924
Journal Article
Peer reviewed
The paper reports on the studies of static and dynamic characteristics of 30 kV diode stacks based on 4H-SiC drift step recovery diodes (DSRDs). It was found that the optimal performance in terms of ...blocking voltage and switching speed can be achieved with 2 kV DSRD dies. Fifteen 2 kV DSRD dies were connected in series and sealed with molding compound. The stacks were dynamically tested in a special oscillator circuit. Repetitive voltage pulses of 30.5 kV with the leading edge of 1.6 ns were demonstrated.
Possibility of utilization of CO-containing fuel in a fuel cell based on a solid oxide protonic conductor (SOFC(H
+)) is demonstrated. Thermodynamic analysis of a methane fed SOFC(H
+) system is ...performed. It is stated that the fuel utilization depends on H
2O/CH
4 mole ratio in the feeding fuel mixture and has a maximum at the ratio of about 2.6. It is stated that average EMF of the SOFC(H
+) is higher than that of an SOFC based on oxygen ion conductor under the same conditions and, hence, the maximum efficiency of the SOFC(H
+) system is about 15% higher than of the SOFC system based on oxygen ion conductor.
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