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An RNA interference-based method was proposed to achieve an inducible knockdown of genes essential for cell viability. In the method, a genetic cassette in which a copper ion-dependent inducible metallothionein promoter controls expression of a siRNA precursor is inserted into a genomic pre-integrated transgene by CRIPSR/Cas9 technology. The endogenous siRNA source allows the gene knockdown in cell cultures that are refractory to conventional transfection with exogenous siRNA. The efficiency of the method was demonstrated in Drosophila ovarian somatic cell culture (OSC) for two genes that are essential for oogenesis: Cul3, encoding a component of the multiprotein ubiquitin-ligase complex with versatile functions in proteostasis, and cut, encoding a transcription factor regulating differentiation of ovarian follicular cells. [ABSTRACT FROM AUTHOR]

The influence of traveling ionospheric disturbances (TID) on the caustic structure of radio waves formed during low-inclination sounding of the ionosphere has been studied. The propagation of an ordinary wave is considered. It has been established that radio waves reflected from the TID form a caustic catastrophe of type A3—a cusp. S-shaped curves formed on graphs describing the Doppler frequency shift, as well as "time loops" on graphs describing the dependence of group time on distance, were studied. Using the methods of the wave theory of catastrophes, the phase and amplitude structures of the wave field in the three-ray region were calculated. [ABSTRACT FROM AUTHOR]

Mathematical modeling of the propagation of radio waves in the decameter range between the transmitter and receiver on inclined paths during the formation of traveling ionospheric disturbances (TID) has been carried out. The features of propagation when moving TIDs in both horizontal and vertical directions were studied. The characteristics of the radio channel: the group delay time of the radio signal, the Doppler frequency shift, the dependence of the ray exit angles on the position of the TID center at various frequencies and types of polarization of electromagnetic waves are calculated. It has been established that when the inhomogeneity moves horizontally, the center of the Doppler shift curve (zero value) move depending on the type of polarization of the radiation. The shape of the Doppler shift curve changes from a sinusoidal shape to a sawtooth with increasing frequency, the group delay curve has a minimum in the region of influence of the TID, and the region of influence of the disturbance itself significantly exceeds its characteristic size. With vertical movement, a three-ray region is formed, characterized by increased values of the Doppler frequency shift and group delay times. [ABSTRACT FROM AUTHOR]

The method of bicharacteristics is used to study the propagation of decameter radio waves in the ionosphere containing the E, F1, and F2 layers and a traveling ionospheric disturbance (TID) upon slightly oblique sounding with frequency-modulated signals. The propagation of both ordinary and extraordinary waves is considered, the ionograms are compared, and their relative shift is studied. The structure of ionograms in the vicinity of caustics, which appear at the reception point at frequencies reflected in the vicinity of the E layer and TID, is studied. The divergence of the ray flux at the point of radiation reception, which determines a decrease in the amplitude, is calculated. [ABSTRACT FROM AUTHOR]

A method for reconstructing the effective frequency of electron collisions is developed on the basis of data on the attenuation and delay of frequency-modulated radio signals during the vertical sounding of the Earth ionosphere. Numerical modeling is realized in the cases of both the single-layer and double-layer models using the method of the extended bicharacteristic system. The ray trajectories of frequency-modulated decametric signals are drawn in the time—altitude coordinates. The signal absorption depending on the frequency, signal amplitude characteristics, and the frequency dependences of the maximal reflection altitude and arrival time are investigated. The dependences of the vertical component of the wave vector on the altitude and time are studied. The developed technique of experimental data processing makes it possible to obtain the dependence of the effective collision frequency on the altitude with the good accuracy. [ABSTRACT FROM AUTHOR]

Results are presented from studying the X-ray diffraction, heat capacities, dielectric permittivities, and coefficients of the volumetric thermal expansion of composite materials obtained by embedding of Rb2ZnCl4 salt into the porous matrices of borosilicate glass with average pore diameters of 46 and 320 nm in the temperature range of 120–350 K. The temperatures of transitions to the incommensurate and ferroelectric phases are determined, along with the freezing temperature of the mobility of domain boundaries in Rb2ZnCl4 particles. A substantial increase in their Curie temperature is observed. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the welding conditions, the temperature and duration of process tempering, and welding flux types on the strength properties of the all-weld metal as applied to low-carbon weld deposits of transport nuclear power units has been investigated. [ABSTRACT FROM AUTHOR]

Abstract: The influence of alloying elements, namely, silicon, manganese, nickel, and molybdenum, contained in the welding wire on the mechanical properties of the metal of automatic submerged-arc welding joints has been investigated. It has been established that the required strength and ductility values and the ductile-to-brittle transition temperature of the weld metal both in the as-welded state and upon high-temperature tempering are achieved by using welding wire with a silicon content of ~0.6% and a manganese content of ~1.5%. [ABSTRACT FROM AUTHOR]

Abstract: The paper describes a technology for welding the assembly joints in power plants of nuclear icebreakers manufactured of heat-resistant 15Cr2MoV steel grades using low-carbon surfacing. The proposed technology is a reliable method for assuring the serviceability of icebreaker nuclear power plants under conditions when the heat treatment of the assembly joint is infeasible. The low-carbon all-weld metal is often prone to softening under the action of repeated process tempering cycles to which the assembly units of the equipment are subjected. [ABSTRACT FROM AUTHOR]

Results are presented for dilatometric and metallographic investigations and determination of microhardness for weld metal made of the materials for the automatic welding of VVER reactor vessels and oil hydrocracking reactor vessels. It is found that small differences in the content of alloying elements, such as nickel, chromium, molybdenum, and vanadium, cause differences in the structure of the weld metal before heat treatment. [ABSTRACT FROM AUTHOR]

The Piwi protein and its orthologs are considered as the key components of the piRNA machinery implicated in transcriptional silencing of transposons. Неre, we show that nuclear localization of the Piwi protein is required not only for transposon repression, but also for proper differentiation of germline stem cells (GSCs). piwi mutation that causes loss of nuclear Piwi and its retention in the cytoplasm leads to the accumulation of undifferentiated GSC-like cells. The analysis of piwi mutation in combination with a bam gene mutation blocking GSC differentiation shows that the loss of nuclear Piwi decreases GSC proliferation rate. This is accompanied by the accumulation of DNA double-strand breaks in GSCs that may be caused by transposition events. Here, for the first time a set of transposons repressed by Piwi in GSCs and surrounding niche cells has been identified. The present study together with our previous data show that nuclear and cytoplasmic Piwi can regulate different stages of the functioning of germinal cells: cytoplasmic Piwi is sufficient to maintain GSCs, while nuclear Piwi localization is necessary for their proper proliferation and differentiation. [ABSTRACT FROM AUTHOR]

A series of studies was conducted in order to refine welding consumables and techniques for girth welding of VVER reactor vessels made from steel 15Kh2MFA-A with standard wire Sv-10KhMFTU. A set of service characteristics of the weld metal that are similar to those of the base metal was obtained, and the specified brittleness transition temperature of the weld metal was reduced considerably. [ABSTRACT FROM AUTHOR]

The evolutionarily conserved nuclear Piwi protein of Drosophila melanogaster is the defining member of the Argonaute small RNA-binding protein family. Guided by piRNAs, Piwi functions in transposon silencing in somatic and germ cells of gonads. We found that in ovarian somatic and germ cells, as well as in the established ovarian somatic cell line, Piwi accumulates predominantly in the nucleolus, the main nuclear compartment which participates not only in rRNA synthesis, but also in various cell stress responses. We have shown the colocalization of Piwi with the nucleolar marker proteins fibrillarin and Nopp140. The piwi mutation which prevents the transport of Piwi to the nucleus and disrupts transposon silencing led to 6-8 fold upregulation of rRNA gene expression, as assessed by the level of transcripts of transposon insertions in 28S rRNA genes. RNase treatment of live cultured ovarian somatic cells depleted Piwi from the nucleolus. The same effect was observed upon inhibition of the activity of RNA polymerase I, which transcribes rRNA genes, but not RNA polymerase II. In contrast, upon heat shock, Piwi concentrated in the nucleolus and was depleted from the nucleoplasm. These results implicate Piwi in RNA polymerase I activity modulation and stress response in the nucleolus. Possible noncanonical Piwi functions are discussed, which are not related to the role of Piwi in transposon silencing. [ABSTRACT FROM AUTHOR]

The development of the reproductive organs and the gametogenesis in animals are complex and multistage processes that require the precise and efficient regulation. In this review, we summarized the recent findings about the essential functions of microRNAs (miRNAs) in the regulation of gene expression during the differentiation of germ cells in spermatogenesis and oogenesis. Most likely, main and common functions of the conserved and highly expressed miRNAs in the male and female reproductive organs of mammals are the control of differentiation and proliferation of cells. Also we discussed a possible involvement of germline-expressed miRNAs in the formation of reproductive barriers and speciation. [ABSTRACT FROM AUTHOR]

Complexes of Piwi family proteins with short piRNAs (Piwi-interacting RNAs) are responsible for silencing transposable elements in animal reproductive organs. In Drosophila melanogaster, three proteins (Piwi, Aub, and Ago3) are members of the Piwi family. Piwi is the nuclear protein of somatic and germinal ovarian cells, whereas Aub and Ago3 are cytoplasmic proteins involved in piRNA amplification in perinuclear granules that constitute special organelles of germinal cells called nuage. Mutations in genes of the piRNA system are known to cause derepression of several transposable elements. In this study, we compared quantitatively changes in expression of a larger number of elements in the case of mutations in the piwi gene, genes aub, mael, and spn-E, which encode proteins of nuage granules, and armi gene coding an RNA helicase, the lack of which does not interfere with cytoplasmic piRNA amplification but disturbs nuclear localization of Piwi protein. We found that the genes piwi, armi, aub, spn-E, and mael interact to induce silencing of some retrotransposons ( HMS-Beagle, Gate and HeT-A); the same genes, except piwi, are involved in repression of I and G elements. We propose that Armi is involved in control of not only nuclear Piwi localization. Our data suggest the relation of nuage proteins Aub, Spn-E, and Mael to Piwi-mediated silencing of retrotransposons Gate and HMS-Beagle in the nucleus. In general, our results corroborate the idea of genome stabilization by means of various silencing strategies specific to different transposable elements. At the same time, our data suggest the existence of yet unknown mechanisms of interplay between nuclear and cytoplasmic components of the piRNA machinery in germinal cells. [ABSTRACT FROM AUTHOR]

Using a program we developed allowing us to take into account zero-field splitting, spin-orbit, and exchange interactions in polynuclear complexes, we have interpreted the temperature dependences of the magnetic susceptibility for the complexes FeCoO(CFCO)(HO)·HO ( 1) and [Co(HO)][CuL(HO)]·3HO ( 2, HL = 1,9-dicyano- 1,9-bis(hydroximino)-3,7-diazanonane-2,8-dione). We have analyzed the differences between the values of the simulation parameters determined within different theoretical models. [ABSTRACT FROM AUTHOR]

The paper presents investigations of magnetic transport properties of prospective materials for fabricating magnetic field transducers, namely, bulk polycrystalline manganites La1 – xA xMnO3 (here A = Sr, Ba, or Pb, and 0.15 < x < 0.55) over a temperature range of 260–300 K. The nonlinearity of the magnetoresistance of these materials as a function of magnetic field intensity has been studied at room temperature. Among the materials investigated in the given temperature range, the composition La0.60Sr0.40MnO3 is most susceptible to the applied magnetic field, and the nonlinearity of its characteristic is minimal. [ABSTRACT FROM AUTHOR]