Search

Most of the stars in the Universe are M spectral class dwarfs, which are known to be the source of bright and frequent stellar flares. In this paper, we propose new approaches to discover M-dwarf flares in ground-based photometric surveys. We employ two approaches: a modification of a traditional method of parametric fit search and a machine learning algorithm based on active anomaly detection. The algorithms are applied to Zwicky Transient Facility (ZTF) data release 8, which includes the data from the ZTF high-cadence survey, allowing us to reveal flares lasting from minutes to hours. We analyse over 35 million ZTF light curves and visually scrutinize 1168 candidates suggested by the algorithms to filter out artefacts, occultations of a star by an asteroid, and other types of known variable objects. The result of this analysis is the largest catalogue of ZTF flaring stars to date, representing 134 flares with amplitudes ranging from −0.2 to −4.6 mag, including repeated flares. Using Pan-STARRS DR2 colours, we assign a spectral subclass to each object in the sample. For 13 flares with well-sampled light curves and available geometric distances from Gaia DR3, we estimate the bolometric energy. This research shows that the proposed methods combined with the ZTF's cadence strategy are suitable for identifying M-dwarf flares and other fast transients, allowing for the extraction of significant astrophysical information from their light curves. [ABSTRACT FROM AUTHOR]

Chromatin repair assembly is an important step in maintaining genome stability. The correct assembly of chromatin is provided by histone chaperones, whose dysfunction can lead to the development of various forms of cancer and a number of hereditary diseases in humans. The effect of remodeling factors completes chromatin repair. The yeast chromatin remodeling complex INO80 plays an important role in chromatin architecture. We used induced mutagenesis and real-time PCR to study the role of INO80 in chromatin repair assembly. In double mutants ies5Δ hsm3Δ (hif1Δ), defects in the structure of nucleosomes caused by mutations hsm3Δ and hif1Δ lead to hypersensitivity of cells to UV radiation and the disappearance of hsm3- and hif1-specific mutagenesis. Double mutants carrying the nhp10Δ mutation and hsm3Δ or hif1Δ mutations were indistinguishable from a single mutant in terms of the lethal effect of UV irradiation, but the high UV-induced mutagenesis characteristic of all mutations disappeared. Thus, it gas been found that mutations in the genes controlling the subunits of the INO80 complex can exhibit strong interactions with mutations in histone chaperone genes. The hypothesis that the Him1 protein performs a chaperone function in the process of chromatin repair assembly has been confirmed. [ABSTRACT FROM AUTHOR]

This work continues the earlier studies focusing on fabrication of heterophase micropowders and consolidated ceramics based on HfB2–HfC–SiC ultra-high-temperature boride/carbide compositions via self-propagating high-temperature synthesis (SHS) and hot pressing (HP). The effect of NH4Cl addition on the morphology and microstructure of the SHS powders was studied. Composite micropowders characterized by particle size of 0.2–10 μm and 40–50% content of the submicron-sized fraction were fabricated. The structure, mechanical and thermophysical properties, kinetics and mechanism of high-temperature oxidation of hot-pressed ceramic materials composed of 57–72 wt % HfB2, 14–20 wt % HfCx, 10–14 wt % SiC, and 8–15 wt % HfO2 were studied. They are found to have hardness up to 18.9 GPa, crack resistance up to 9.7 MPa m0.5, bending strength up to 400 MPa, temperature diffusivity up to 22.6 mm2/s, and thermal conductivity up to 59 W/(m K). The power law describes their oxidation kinetics. The protection mechanism against oxidation involves the formation of a multilayered heterogenous oxide film consisting of HfO2, HfSiO4, and borosilicate glass. [ABSTRACT FROM AUTHOR]

The achievements of the present regulatory and technical base for assessing quantitative indicators of ecosystem status are analyzed on the basis of the statistics of types of works for studying the abiotic spheres of the Earth (lithosphere, pedosphere, atmosphere, and surface hydrosphere) as a component of engineering-ecological surveying. Achievements concerning the regulation of indicators of the status of abiotic spheres of ecosystem are described. Methods for further improvement of the regulatory and technical base are outlined, using the doctrine of ecological functions of the lithosphere as a fundamental integral characteristic of the abiotic spheres of ecosystems and the systematization of individual indicators by introducing four categories of integral indicators (resource, geochemical, geophysical, and geodynamic). Attention is drawn to the need to elaborate the integral indicators of all abiotic spheres of ecosystems on the basis of development of ecological geology. Various approaches for assessing such integral indicators are considered. A variant of their determination on the basis of the summary indicators method is proposed. [ABSTRACT FROM AUTHOR]

A way of intelligently predicting random processes is described, based on more complete use of information about statistical patterns of the evolution of an observed process. At the stage of training the predictive algorithm, the feature space is enriched with the parameters of mixed probabilistic models that allow the construction and reconstruction of the coefficients of a stochastic differential equation describing the given random process. The use of additional statistical information imposes additional conditions on the search area and therefore narrows the set of considered options. Learning is thus targeted by excluding impossible or unlikely options in advance, making it more effective and forecasts more accurate. [ABSTRACT FROM AUTHOR]

The stability index of petroleum disperse systems can be calculated using continuous scanning of the optical profile of the asphaltene precipitation, taking into account the induction period of the asphaltene particle aggregation under the preset external conditions. Modification of the ASTM D7061 procedure allows taking into account the induction period of the asphaltene aggregation and different aggregation mechanisms (diffusion- and reaction-limited aggregation). This opens prospects for improving the procedures for express analysis of asphaltene-containing dispersions in the future. The control of the stability of asphaltene-containing systems is the base element for developing of a mathematical model of the kinetics of chemical processes occurring in a stratum, pipeline, or reactor. [ABSTRACT FROM AUTHOR]

At the S-300 facility (2 MA, 400 kV, 100 ns), the generation of ultra hard X-rays was observed upon magnetic compression of cylindrical nested aluminum arrays with a linear mass of ~350 μg/cm, consisting of aluminum wires with a diameter of 15 μm. At the final phase of compression, a compact pinch is formed, consisting of a large number of hot spots arranged along the axis. This phase is accompanied by the emission of soft X-rays with a duration of ~10 ns. Simultaneously with the soft X-ray pulses, ultra hard X-rays with an energy exceeding 450 keV were detected. Ultra hard X-rays were measured with scintillation detectors shielded with lead 20–70 mm thick. The main cause of overvoltage on the plasma column appears to be sausage instability. [ABSTRACT FROM AUTHOR]

The main advantages of direct laser deposition (DLD) of large-sized products are discussed by the example of the internal core baffle of a pressurized water reactor (VVER core baffle). The problem of product damage during operation as a part of reactor is considered. Powder materials made of 08Cr18Ni10Ti and 10Cr16Ni25MoTi stainless steels are produced to develop the DLD process. Optimization of the core baffle design is carried out to improve operating reliability. Samples and experimental small fragments of the core baffle for complex research and tests are manufactured by the DLD method. The concept of an experimental DLD unit for large-scale parts is advanced. [ABSTRACT FROM AUTHOR]

The possibility of recovering Rh, Ru, and Pd from nitric and hydrochloric acid solutions with Fe4[Fe(CN)6]3 was examined. The conditions for practically complete recovery of the sum of platinum group metals from nitric acid solutions at the acid concentrations in the interval 1–5 M were determined. From hydrochloric acid solutions, Rh and Ru can be recovered at the acid concentration of 0.1–0.5 М. Pd is completely recovered from both 1–5 M nitric and 1–5 M hydrochloric acid solutions. From simulated spent nuclear fuel reprocessing solutions, Cs, Mo, and Zr are recovered to different extents jointly with Rh, Ru, and Pd. The Rh and Ru sorption isotherms are described by the Langmuir equation. The Pd sorption isotherm has a nonstandard two-step shape. Fe4[Fe(CN)6]3 can be recommended for recovering platinum metals from process solutions, including those from reprocessing of spent nuclear fuel and spent catalysts. [ABSTRACT FROM AUTHOR]

Efficient stereoselective methods for the synthesis of 5α-androst-1-ene-3β,17β-diol, which is used as a reference compound for identification of anabolic steroids and their metabolites, were elaborated. The key factor of the synthesis is the use of the sodium borohydride—cerium(III) chloride system as a reducing agent. [ABSTRACT FROM AUTHOR]

The issues of developing a general classification of geological processes that are the subject of research in modern engineering geodynamics, one of the areas of engineering geology, are considered. A new general classification of geological processes for the purposes of engineering geology is proposed, taking into account the disadvantages of previous similar classifications and covering the whole variety of both natural geological processes and their technogenic analogues, that is, engineering-geological processes. [ABSTRACT FROM AUTHOR]

Context. We provide the first results from the complete SNAD adaptive learning pipeline in the context of a broad scope of data from large-scale astronomical surveys. Aims. The main goal of this work is to explore the potential of adaptive learning techniques in application to big data sets. Methods. Our SNAD team used Active Anomaly Discovery (AAD) as a tool to search for new supernova (SN) candidates in the photometric data from the first 9.4 months of the Zwicky Transient Facility (ZTF) survey, namely, between March 17 and December 31, 2018 (58 194 = MJD= 58 483). We analysed 70 ZTF fields at a high galactic latitude and visually inspected 2100 outliers. Results. This resulted in 104 SN-like objects being found, 57 of which were reported to the Transient Name Server for the first time and with 47 having previously been mentioned in other catalogues, either as SNe with known types or as SN candidates. We visually inspected the multi-colour light curves of the non-catalogued transients and performed fittings with different supernova models to assign it to a probable photometric class: Ia, Ib/c, IIP, IIL, or IIn. Moreover, we also identified unreported slow-evolving transients that are good superluminous SN candidates, along with a few other non-catalogued objects, such as red dwarf flares and active galactic nuclei. Conclusions. Beyond confirming the effectiveness of human-machine integration underlying the AAD strategy, our results shed light on potential leaks in currently available pipelines. These findings can help avoid similar losses in future large-scale astronomical surveys. Furthermore, the algorithm enables direct searches of any type of data and based on any definition of an anomaly set by the expert. [ABSTRACT FROM AUTHOR]

Study of the genetic instability patterns of cells after exposure to UV radiation is an urgent task, since this effect may precede cancer. New experimental results associated with survival and genetic instability of haploid and diploid Saccharomyces cerevisiae yeast cells of the wild type and UV sensitive mutants surviving after exposure to 254 nm UV light are presented and discussed. The dependence of cell survival on UV light fluence was sigmoid for the haploid strain of the wild type and exponential for UV sensitive strains. The shape of the survival curves for diploid wild-type strains was also sigmoid, while homozygous diploid UV sensitive mutants exhibited both exponential and sigmoid survival curves always being more sensitive than their parental strains. Genetic instability was determined by the delayed formation of clones by cells surviving UV exposure. This effect was shown to be well expressed and attained 100% for diploid cells of both the wild type and sensitive mutants that are defective in the repair of UV damage. On the contrary, haploid cells showed significantly less genetic instability (30–50%) independently of their sensitivity. It is concluded that genetic instability is mainly determined by cell ploidy rather than the shape of the survival curve and the cell ability to recover from UV radiation damage, as previously stated. [ABSTRACT FROM AUTHOR]

Statistical regularities of the intra- and interannual variability of sensible and latent heat fluxes in the North Atlantic, including those based on identifying regression dependencies with various averaging of time series, are investigated. Various characteristics of fluxes are estimated, such as maxima and minima over the water basin, mean values, and medians. Based on ERA5 reanalysis data in 1979–2021, the evolution of these values in the North Atlantic is studied and compared with the behavior of the heat fluxes, both from year to year and within a mean climatic year. It is shown that there is a positive trend in the fluxes; parameters of the fluxes are estimated. The spatiotemporal variability of the extreme characteristics of fluxes (maximum and minimum) over the computational domain at fixed times is analyzed. [ABSTRACT FROM AUTHOR]

Cobalt triflate hexahydrate [Co(H2O)6](CF3SO3)2 (I) is crystallized from aquos solution. The dehydration of salt I at 200°C in an argon flow affords anhydrous salt Co(CF3SO3)2 (II). The crystal structures of compounds I and II are determined from single crystal and powder X-ray diffraction data, respectively. Compound I is isostructural to [Ni(H2O)6](CF3SO3)2 and crystallizes in the space group P m1, а = 7.3914(16), с = 8.704(2) Å, V = 411.8(2) Å3, Z = 1. The structure of compound II (space group R , а = 4.9996(1), с = 31.3137(8) Å, V = 677.86(3) Å3, Z = 3) belongs to the structural type M(CF3SO3)2, where M = Mg, Ca, and Zn. In the structures of both compounds, the cobalt atoms are in the octahedral environment of the oxygen atoms belonging to the water molecules (I) or triflate groups (II). In compound I, the [Co(H2O)6]2+ cations localized in the nodes of a regular triangular network are linked with the (CF3-SO3)– anions via hydrogen bonds to form layers parallel to the (001) plane. When compound I is dehydrated to form compound II, the [CoO6] octahedra are coupled via the μ3-CF3SO3 group with the retention of the layered structure. The synthesized compounds are characterized by IR spectroscopy, TG/DTA/MS. The results of studying the magnetic properties of compounds I and II indicate no magnetic ordering at low temperatures and correspond to the paramagnetic behavior of compounds I and II at high temperatures with a considerable contribution of the spin-orbital interaction to the effective magnetic moment of the cobalt atom. [ABSTRACT FROM AUTHOR]

We consider inhomogeneous continuous-time Markov chains with vanishing perturbations. It is proved that, under some natural conditions, the limiting regimes of the initial and perturbed chains coincide. We obtain explicit estimates, which allow construction of the limiting regime of the perturbed chain, and show how these results can be used in the analysis of several known classes of queuing systems. [ABSTRACT FROM AUTHOR]

Extreme values are considered in samples with random size that have a mixed Poisson distribution being generated by a doubly stochastic Poisson process. We prove some inequalities providing bounds on the rate of convergence in limit theorems for the distributions of max-compound Cox processes. [ABSTRACT FROM AUTHOR]

Non-uniform estimates of the rate of convergence in the central limit theorem for sums of independent identically distributed summands are refined under the condition that the summands possess moments of orders no higher than two. [ABSTRACT FROM AUTHOR]

During the electroreduction of 4-phenyl-1,2,4-triazoline-3,5-dione under aprotic conditions, a chain reaction of its transformation to triazolo[1,2-a]triazole-1,3,5,7-tetraone is initiated, with the mechanism including the transformation of the initially formed radical anion of the starting compound into the radical anion of the product, the difference in the formation potentials of which is 2.39 V, that corresponds to an electron upconversion value of over 50 kcal mol−1. For complete conversion of 4-phenyl-1,2,4-triazoline-3,5-dione in both MeCN and THF, it was enough to pass 0.1 F mol−1 of electricity at the reduction potential of the starting compound. Cyclic voltammetry was used to study in detail the reaction mechanism, which includes a rapid reversible dimerization to π-dimer of the initially formed radical anions, relatively slowly undergoing conversion into the key intermediate of the entire process, a σ-dimeric dianion. Further, the σ-dimeric dianion acts as an electron donor for the molecule of the starting compound, turning itself into a separated dimeric radical anion, which eliminates nitrogen with the formation of the radical anion of the product, that also reduces the molecule of the starting substrate, thus closing the catalytic cycle. [ABSTRACT FROM AUTHOR]

The reaction of perfluorobiphenyl with tert-butylamine in an autoclave affords the aminodefluorination product, N-tert-butyl-2,2′,3,3′,4′,5,5′,6,6′-nonafluorobiphenyl-4-amine, and the oxidation of the latter with meta-chloroperbenzoic acid gives the new stable nitroxide radical, N-tert-butyl-N-(2,2′,3,3′,4′,5,5′,6,6′-nonafluorobiphenyl)amine N-oxide, in quantitative yield. According to the X-ray diffraction analysis, the crystallization from heptane results in the spontaneous precipitation of the solid paramagnet as one of the two polymorphs, either triclinic (P 1 ¯) or monoclinic (P21/n). The electrochemical oxidation and reduction of nitroxide occur irreversibly. The heating of a toluene solution of the paramagnet leads to the oxidation of the solvent and the generation of the corresponding hydroxylamine and the benzyl radical, which enters into the recombination reaction with the initial radical to form alkoxyamine. [ABSTRACT FROM AUTHOR]

The possibility of palladium recovery from nitric acid solutions simultaneously with the in situ synthesis of iron(III) hexacyanoferrate(II) (HCF) was studied. The molar ratio of the reagents Pd : PFC : Fe(III) = 1 : 2 : 2 (PFC is potassium ferrocyanide) was found to provide complete palladium recovery in the range of nitric acid concentrations of 1–5 M. Almost all cesium and significant amounts of molybdenum and silver are separated from the solution, simulating HLW from spent nuclear fuel reprocessing. [ABSTRACT FROM AUTHOR]

The magnetoresistive effect in MnSe1-XTeX manganese chalcogenides with a substitute concentration of X=0.1 is studied by impedance spectroscopy. The magnetoimpedance above the Neel temperature is found. The obtained experimental data are explained in the framework of the model of existence of magnetic nanoareas of two types. Two activation energies in the low- and high-frequency regions are determined from the frequency and temperature dependences of the permittivity described in the Debye model. The extrema found in the temperature dependence of the pyroelectric current are consistent with the maxima in the temperature dependence of magnetization. Temperature dependence of the carrier relaxation time is established. The magnetocapacitance of the MnSe1-XTeX solid solutions is found. The change in the carrier type above the Neel temperature and the temperature of the transition to the magnetically ordered state in the MnTe nanoarea is established. [ABSTRACT FROM AUTHOR]

Based on the analysis of the results of experiments on deuterated fibers, frozen deuterium fibers, and heterogeneous low-density targets, it can be concluded that low-density monodisperse cryogenic targets with a complex microheterogeneous structure are most suitable for the further investigation of emitting Z‑pinches of multiterawatt power. These studies have shown that using the available equipment it is possible to obtain cryogenic targets of hydrogen or its isotopes of the following types: cylindrical "thick" fibers up to 10 cm long and 40 to 300 µm in diameter; "thin" fibers with a length of 5 to 10 cm with a diameter of 30 to 40 µm, and monodisperse cryogenic targets. In general, cryogenic monodisperse targets are a flow of solid monodisperse granules of hydrogen or its isotopes with a diameter of 10 to 100 μm, a velocity of up to 100 m/s, and a frequency of occurrence in the discharge region from 0.01 Hz to 500 kHz. Using outlet nozzles with a large number of outlet holes, it is possible to obtain monodisperse cryogenic targets with a complex microheterogeneous structure, consisting of tens and hundreds of granules. In addition, the flow of granules can be controlled, e.g., by focusing it on the desired spatial point. The relative spread of targets in velocity and size does not exceed 0.1%. The use of cryogenic deuterium targets with a complex microheterogeneous structure makes it possible to increase the deuterium concentration in the target several times compared to other types of targets. A high initial concentration of deuterium and effective ionization of the target material can lead to a significant increase in the neutron yield due to the power-law dependence of the yield on concentration (Y ~ n2). Additional factors that can significantly increase the neutron yield are: the power dependence of the neutron yield on the discharge current and the transition from a deuterium target to a target made from a deuterium–tritium mixture. [ABSTRACT FROM AUTHOR]

Abstract—The issues of developing a general classification of continental natural and technogenic ecological–geological systems that are the subject of research in modern ecological geology, are considered. A classification that considers the composition and characteristics of the components of ecological–geological systems is proposed. [ABSTRACT FROM AUTHOR]

The results of integrated comparative tests of the heat sinks fabricated by conventional technology and selective laser melting are presented. The test results have been analyzed including the determination of the main service characteristics of the heat sinks. A conclusion has been made about the ability to apply the heat sinks fabricated by selective laser melting as part of spacecraft. [ABSTRACT FROM AUTHOR]

The results of integrated comparative tests of the heat sinks fabricated by conventional technology and selective laser melting are presented. The test results have been analyzed including the determination of the main service characteristics of the heat sinks. A conclusion has been made about the ability to apply the heat sinks fabricated by selective laser melting as part of spacecraft. [ABSTRACT FROM AUTHOR]

In this paper, statistical regularities of the intra-annual variability of heat fluxes in the North Atlantic during the ocean–atmosphere interaction are analyzed. A diffusion random process is considered as a mathematical model of the variability of heat fluxes. Parameters of this process, that is, the drift vector and the diffusion (or standard deviation) matrix, are estimated statistically using original methods. According to ERA-5 reanalysis data for 2011–2020, the evolution of these coefficients in the North Atlantic is studied and their behavior is compared with the behavior of the heat fluxes themselves. Zones of maximum, minimum, and average values of these flows are identified throughout the area under study with daily and 6-h averaging; their behavior and the behavior of their daily variability are described as random values throughout the year. Statistical fitting of parametric models of their distributions is implemented. Areas of the North Atlantic in which systematic factors are of decisive importance (the drift parameter exceeds the diffusion parameter) and vice versa are determined. This effect is discussed in terms of the behavior of the parameters of the probability distributions for increments of the processes under consideration. The spatiotemporal variability of the extreme characteristics of fluxes (maximum and minimum over the computational domain at a fixed time instant) is analyzed. [ABSTRACT FROM AUTHOR]

A new method for a remote control of a space robot designed to perform operations in a complex external environment. It's dealing with objects that can move freely in space or limited by holonomic bonds that limit their possible movements. This is a typical situation when performing assembly operations in discovering space. The method is based on the use of an important feature that characterizes each operation performed on the interaction of the working tool of the robot with the external objects in the environment. [ABSTRACT FROM AUTHOR]

Various methods of stability analysis of an airplane with a MIMO control system are considered in the framework of frequency analysis. They assume that the control system is open for selected signal with other loops closed or that system is open for all signals of selected loops and allow solving the stability equation and calculating the eigenvalues of the matrix of transfer functions. It is shown that all methods deal with different forms of the same equation, and thus the equivalence of methods considered for calculating closed-loop stability domains is proved. The application of methods is demonstrated for calculation of stability domains for an airplane equipped with MIMO stability and control augmentation system in lateral motion that uses ailerons and rudder as control surfaces. It is shown that in the case of a MIMO system, an open-loop transfer function that defines closed-loop stability is a nonlinear function of control system gains; this introduces uncertainty to the concept of amplitude and phase margins. [ABSTRACT FROM AUTHOR]

This article presents and analyzes the results of a study on the frost resistance of clay-cement concrete used for repairing the anti-filtration element of the earth dam at the Kurei Hydropower Plant (HPP), made in the form of a wall in the ground. It is concluded that the material of this composition can be used to create and repair anti-filtration elements in other dams. The need to develop a special method for conducting laboratory tests of clay-cement concrete samples, which differ in physical and technical characteristics from conventional concrete, is highlighted. [ABSTRACT FROM AUTHOR]

We present results from applying the SNAD anomaly detection pipeline to the third public data release of the Zwicky Transient Facility (ZTF DR3). The pipeline is composed of three stages: feature extraction, search of outliers with machine learning algorithms, and anomaly identification with followup by human experts. Our analysis concentrates in three ZTF fields, comprising more than 2.25 million objects. A set of four automatic learning algorithms was used to identify 277 outliers, which were subsequently scrutinized by an expert. From these, 188 (68 per cent) were found to be bogus light curves – including effects from the image subtraction pipeline as well as overlapping between a star and a known asteroid, 66 (24 per cent) were previously reported sources whereas 23 (8 per cent) correspond to non-catalogued objects, with the two latter cases of potential scientific interest (e.g. one spectroscopically confirmed RS Canum Venaticorum star, four supernovae candidates, one red dwarf flare). Moreover, using results from the expert analysis, we were able to identify a simple bi-dimensional relation that can be used to aid filtering potentially bogus light curves in future studies. We provide a complete list of objects with potential scientific application so they can be further scrutinised by the community. These results confirm the importance of combining automatic machine learning algorithms with domain knowledge in the construction of recommendation systems for astronomy. Our code is publicly available.1 [ABSTRACT FROM AUTHOR]

In eukaryotes, DNA damage tolerance (DDT) can be achieved through two mechanisms. One mechanism is mediated by the homologous recombination repair proteins. The other is under control of the RAD6 epistatic group genes and is divided into two more pathways, including error-free and error-prone ones. The error-prone mechanism, termed translesion DNA synthesis (TLS), is carried out with the participation of specialized TLS DNA polymerases. TLS is an important source of mutational changes in DNA. On the contrary, upon the realization of RAD6-dependent error-free DDT mechanism, relatively higher accuracy of DNA synthesis is provided by the use of intact sister chromatid or a homologous chromosome as a template to continue replication. In this case, after the replication fork stalling at the site of damage, the 3' end of the synthesized strand is transferred to an intact homologous DNA molecule, the synthesis continues for some length on a new template, and then the elongated strand is transferred back to the original chromatid. Inactivation of most genes that control the error-free DDT mechanism either does not affect the level of UV-induced mutagenesis or decreases it. Exceptions include genes belonging to the HSM3 epistatic group. Mutations in the genes of this group lead to a considerable increase in the frequency of UV-induced mutagenesis. This review focuses on the error-free DDT pathway, and attempts to substantiate the role of the HSM3 epistatic group genes in a series of molecular events that lead to the error-free bypass of replication-blocking lesions in budding yeast are made. [ABSTRACT FROM AUTHOR]

Results are presented from a physicochemical study of magnetite magnetic fluid of synthesized with addition of graphene. It is shown that adding graphene during the synthesis of the dispersed phase affects the specific surface of the magnetic phase, the thermal stability, the viscosity, and the heat capacity of the magnetic fluid. [ABSTRACT FROM AUTHOR]

In eukaryotes, DNA damage tolerance (DDT) is determined by two repair pathways, homologous repair recombination (HRR) and a pathway controlled by the RAD6-epistatic group of genes. Monoubiquitylation of PCNA mediates an error-prone pathway, whereas polyubiquitylation stimulates an error-free pathway. The error-free pathway involves components of recombination repair; however, the factors that act in this pathway remain largely unknown. Here, we report that the HIM1 gene participates in error-free DDT. Notably, inactivation RAD30 gene encoding Polη completely suppresses him1-dependent UV mutagenesis. Furthermore, data obtained show a significant role of Polη in him1-dependent mutagenesis, especially at non-bipyrimidine sites (NBP sites). We demonstrate that him1 mutation significantly reduces the efficiency of the induction expression of RNR genes after UV irradiation. Besides, this paper presents evidence that significant increase in the dNTP levels suppress him1-dependent mutagenesis. Our findings show that Polη responsible for him1-dependent mutagenesis. [ABSTRACT FROM AUTHOR]

The phosphatase complex PPH3 consists of three subunits: catalytic Pph3 and auxiliary Pph2 and Psy4. Pph3 also forms a double complex with subunit Psy2, which binds to kinase Rad53 and dephosphorylates it without recruiting the third subunit. The triple complex dephosphorylates γH2A. We have previously shown that gene HSM6 corresponds to gene PSY4 on the genetic map of Saccharomyces cerevisiae. Mutation hsm6-1 increases the rate of spontaneous and UV-induced mutagenesis. In this work, we have shown that mutations in gene PPH3 increase the rate of spontaneous reparative mutagenesis sevenfold, while mutations pph3Δ and hsm6-1 show an epistatic effect. At high doses, the frequency of UV-induced mutations in mutants pph3Δ, psy4Δ, and hsm6-1 is the same and exceeds the level of mutagenesis in the wild-type strain by approximately twofold. All mutants show a higher (approximately 10-fold) frequency of γ-induced mutations compared to the wild-type strain. The combination of mutations in genes encoding PPH3 subunits and mutations in MMS2 and XRS2, which control an error-free postreplication repair pathway, leads to blocking of PPH3-specific UV-induced mutagenesis. Thus, we have identified the PPH3 complex as a novel factor involved in the regulation of the error-free branch of postreplication repair. The double mutant for genes PTC2 and PTC3, encoding the other two phosphatases that dephosphorylate Rad53, does not differ from the wild-type strain with respect to UV-induced mutagenesis and survival. This means that hyperphosphorylation of only the Pph3-specific sites of protein Rad53 and histone H2A increases the level of UV mutagenesis. [ABSTRACT FROM AUTHOR]