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Results of the measurements of neutron spectra at two points at the intense resonance neutron source (IREN) of the JINR's Laboratory of Neutron Physics are presented. Powerful neutron fluxes are obtained using an electron accelerator and the thick tungsten target, in which neutrons are produced by bremsstrahlung gamma-quanta of electrons hitting the target. The tungsten target is placed in a cylindrical vessel filled with water. Neutron spectra were obtained using a multisphere Bonner spectrometer at two points behind biological shielding. Based on the spectra obtained, the effective neutron dose rates at the measurement points were determined, which is of importance both for assessing the radiation situation at IREN and for comparison with the readings of neutron dosimeters of the automated radiation monitoring system. [ABSTRACT FROM AUTHOR]

Thallium ecotoxicity was assessed in laboratory model experiments by changing in microbiological, biochemical, and phytotoxic properties of soils in the South of Russia: ordinary chernozem (Haplic Chernozem (Loamic)), seropesok (Eutric Arenosol), and slightly unsaturated brown forest soil (Eutric Cambisol), differing in texture, pH, and organic matter content. There was usually a direct relationship between Tl concentration and the deterioration rate of the studied soil properties. The ecotoxicity of Tl nitrate was higher as compared to Tl oxide. The ecotoxic effect of Tl was the strongest for chernozem and seropesok within 10 days and for brown forest soil within 30 days after contamination. Restoration of biological soil properties was recorded on the 90th day. The resistance to Tl contamination was the greatest for ordinary chernozem and the smallest for seropesok. The results obtained indicate a high ecotoxicity of Tl. [ABSTRACT FROM AUTHOR]

Enzymatic activity of soils is the most important diagnostic indicator of the ecological state of soils affected by various types of anthropogenic impact. The aim of the study was to evaluate the enzymatic activity of ordinary chernozem (Haplic Chernozem) contaminated with Ag, Bi, Te, and Tl. Ten enzymes (catalase, dehydrogenase, peroxidase, polyphenol oxidase, ascorbate oxidase, ferrireductase, protease, phosphatase, invertase, and urease) were analyzed. According to the degree of inhibition of enzymes, heavy metals formed the following sequence: Tl > Ag > Bi > Te. With an increase in the concentration of heavy metals, the toxic effect on the activity of enzymes increased. The oxidoreductases showed greater sensitivity to Ag, Bi, Te, and Tl contamination than hydrolases. Among oxidoreductases, the highest sensitivity was found for ferrireductase, and the lowest one for ascorbate oxidase. According to the activity of enzymes of the hydrolase class, invertase was the most sensitive, and urease was the least sensitive. When contaminated with Ag, Bi, and Te, invertase had the highest informative value, and when contaminated with Tl, urease and polyphenol oxidase were the most informative. Among the enzymes of the oxidoreductase class, the highest information value was found for peroxidase, and the lowest one for ascorbate oxidase. Among the enzymes of the hydrolase class, invertase was the most sensitive, and phosphatase was the least sensitive. The results of the study can be used to assess the ecological state of soils contaminated with Ag, Bi, Te and Tl. [ABSTRACT FROM AUTHOR]

This article presents a description of the experiment on the Joint Institute for Nuclear Research (JINR) Phasotron proton beam for a laboratory model of a space instrument for the gamma spectrometry of celestial bodies based on the method of tagged charged particles of galactic cosmic rays. One feature of the experiment is the use of a p-type high-purity germanium semiconductor detector as part of the model. [ABSTRACT FROM AUTHOR]

Soil tolerance towards contamination with platinum nanoparticles (PtNP) was assessed using biological parameters for soils of southern Russia differing in particle-size composition, organic matter content, and soil reaction. Model laboratory experiments were performed with samples from the upper (0–10 cm) layer of soils with contrasting genetic characteristics, i.e., ordinary chernozem (Haplic Chernozem (Loamic)), brown forest soil (Eutric Cambisol), and gray sandy soil under pine stand (Eutric Arenosol). PtNP concentrations of 0.01, 0.1, 1, 10, and 100 mg/kg were studied. Soil tolerance was estimated using sensitive and informative biological indices: the total number of bacteria, the activity of catalase and dehydrogenases, and germination degree of radish seeds, and radish root length. In most cases, low PtNP concentrations (0.01, 0.1, and 1 mg/kg) did not affect reliably the biological state of soils, whereas higher doses (10 and 100 mg/kg) worsened biological characteristics. The enzymatic activity of PtNP-contaminated soils decreased to a lesser extent than the phytotoxic and microbiological indices. Ordinary chernozem showed a higher tolerance towards PtNP contamination than brown forest soil and gray sandy soil. The results of this study can be used for predicting ecological risks of soil contamination with PtNP and for assigning the maximum permissible concentration for platinum in different soils. [ABSTRACT FROM AUTHOR]

The NICA accelerator complex includes beam transfer lines and stations for applied research. The first commissioning of the Station of Chip Irradiation (SOCHI) was performed at the end of 2021with С4+ heavy ions extracted from the linear accelerator (HILAC) at an energy of 3.2 MeV/n. The new SOCHI beam transfer line is integrated in the existing HILAC-Booster beamline. The Irradiation Setup for Components of Radioelectronic Apparatus (ISCRA) with ion energy ranging from 150 to 500 MeV/n and the Setup for Investigation of Medical Biological Objects (SIMBO) with the ion energy ranging from 400 to1100 MeV/n are based on the beams extracted from Nuclotron. The equipment of ISCRA and SIMBO stations has been manufactured and is planned to mount in the end of 2022. The beamlines are being designed now. The technical parameters of the beamlines and stations and the results of the first run of the SOCHI station are presented in this study. [ABSTRACT FROM AUTHOR]

The proportion of splenocytes with a high level of DNA double-strand breaks was determined in mice exposed to primary and secondary radiation created by bombarding of a concrete barrier (thickness 20, 40, and 80 cm) by 650 MeV protons. The proportion of splenocytes with a high level of DNA double-strand breaks was assessed by flow cytometric analysis of γH2AX+ and TUNEL+ cells. It is shown that concrete barrier can significantly reduce primary proton radiation; the severity of negative biological effects in mice irradiated in the center of the proton beam decreased with increasing the thickness of this barrier. However, the spectrum of secondary radiation changes significantly with increasing the barrier thickness from 20 to 80 cm and the distance from central axis of the beam from 0 to 20 cm, and the proportion of the neutron component increases, which also causes negative biological effects manifesting in a significant (p<0.05) increase in the percentage of splenocytes with a high level of DNA damage in mice irradiated at a distance of 20 cm from the center of the proton beam and receiving relatively low doses (0.10-0.17 Gy). [ABSTRACT FROM AUTHOR]

Abstract—The Space Research Institute of the Russian Academy of Sciences (SRI RAS) and the Joint Institute for Nuclear Research (JINR) have been cooperating in nuclear planetology for 25 years. From the JINR, employees at the Laboratory of Neutron Physics and the Laboratory of Radiation Safety are involved in joint activities. During this time, a number of space instruments have been developed based on gamma and neutron spectroscopy, for which the JINR carried out detailed ground-based calibrations using various radiation sources and planetary soil models. Most of this scientific equipment is already operating on orbital and landing spacecraft and provide unique scientific data on the presence and distribution of water (ice) on the surface of the Moon and Mars and the elemental composition of the soil. [ABSTRACT FROM AUTHOR]

Calculated data on the differential and total albedo of neutrons of relativistic energies incident on ordinary concrete are presented, and an approximation of the energy dependence of the total neutron albedo in the energy range up to 50 GeV is proposed. [ABSTRACT FROM AUTHOR]

The most important condition for starting work at the NICA accelerator complex, which is a powerful source of ionizing radiation, is to obtain a sanitary-epidemiological conclusion with the justification of a sanitary-protection zone around the facility. The size and configuration of the sanitary-protective zone around the NICA complex are determined by the mode of operation and the loss of particles in its various elements. Based on the calculations of the radiation situation performed earlier, the boundaries of the sanitary-protective zones have been defined for the heavy ions collision mode of the collider operation and for the additional mode in which high-energy protons interact in the collider. [ABSTRACT FROM AUTHOR]

The article presents results of ground calibrations of the FREND neutron telescope installed onboard the TGO spacecraft of the Russian-European ExoMars project. The main goal of the FREND space experiment is to measure hydrogen content in the subsurface layer of Mars to a depth of 1 m. High resolution maps of water mass fraction in the regolith are constructed based on these measurements. During ground physical calibrations, assessments of effective areas and measurements of angular sensitivity functions were obtained for each of the five FREND detectors. We demonstrate that FREND measurement characteristics correspond to its declared scientific goals and allow detecting and investigating local areas with enhanced water/water ice concertation on the subsurface of Mars with high spatial resolution of up to 60–200 km. [ABSTRACT FROM AUTHOR]

A very urgent problem for space radiobiology is to model a chronic GCR exposure concerning simulations with animal models of human risks. However, it was impossible to realize similar irradiation in ground-based conditions until today because the use of heavy-ion accelerators for a long time for this purpose is not realistic. The booster of the Nuclotron—one of the heavy-ion accelerators of the NICA complex of Joint Institute for Nuclear Research—provides this unique possibility. The booster accelerates ions 197Au to 578 MeV/n with a charge state of 31+. Before injection of the booster beam to the main heavy-ion accelerator "Nuclotron", the booster ions are fully stripped (to charge state 79+) by a thin copper foil. The efficiency of stripping is about 90%. The beam of remaining 10% of ions with no-target charge states will be directed to the trap. A small part of this beam can be used to generate the stable reference radiation field with parameters similar to the space radiation for chronic exposure of biological samples. This operation mode will continue 22 hours every day for eight months in the year at the NICA collider work with 197Au ions. The variant of such the field is discussed in the article. [ABSTRACT FROM AUTHOR]

Radiobiological experiments with the irradiation of various biological samples by nuclei from boron to neon with a primary energy of 30–50 MeV/nucleon are performed on the U400M cyclotron of the Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research. The linear energy transfer (LET) of the nuclei in samples is calculated using the code Lise++. For reducing the energy of nuclei and increasing their LET, aluminum filters with different thickness are placed before samples. The presence of filters and other absorbers before a sample results in the production of secondary charged particles whose LET may strongly differ from the LET of primary nuclei of the beam. This also affects the accuracy of calculating the absorbed dose. For this reason, detailed calculations of particle fields in samples are performed using the Monte Carlo code for radiation transport in matter PHITS 3.20 for several variants of sample irradiation with thick absorbers before samples. The calculated LET distributions are analyzed and compared with the calculations using the code Lise++. [ABSTRACT FROM AUTHOR]

The results of using the FLUKA package to calculate the radiation environment around building no. 1 of the Laboratory of High Energy Physics, which contains the ion injection systems, booster, and Nuclotron of the NICA complex in operation for the collider and for experiments with fixed targets, are presented. The calculation has been performed for the mode of 197Au ion acceleration to an energy of 578 MeV/n The main dose-forming component of the radiation field around the building is neutrons of a wide energy range. Detailed models of an ion acceleration ring and the geometry of shields and building details are used in the calculation. The calculation results indicate that the adopted design decisions with the given rates of ion losses will ensure compliance with radiation-protection norms during the operation of the NICA booster. [ABSTRACT FROM AUTHOR]

The results of the second stage of laboratory tests of the space gamma-spectrometer model on the phasotron installed at the JINR Laboratory of Nuclear Problems are presented. Tagged protons are applied in these experiments. Comparative estimates of the sensitivity of the tagged-proton method used aboard lander stationary or mobile platforms to detect inhomogeneities in the underlying surface are obtained. Composite models of planetary matter consisting of silicon oxide, aluminum, and iron are used to imitate space experiments. [ABSTRACT FROM AUTHOR]

The abiotic phosphorylation of nucleosides is a major hurdle in origin‐of‐life studies. We suggest a plausible pathway for the synthesis of adenosine nucleotides from adenosine and NaH2PO4 under radiative conditions mimicking the solar wind in the presence of a meteorite of the aubrite‐type. Hydroxyapatite also performed as a mineral heterogeneous phosphorus source. Adenosine polyphosphate derivatives and inorganic polyphosphates were detected in the reaction mixture, highlighting the high reactivity of the system. Both the total yield of adenosine nucleotides and the conversion of adenosine increased upon performing the irradiation in the presence of formamide (NH2CHO) and aubrite. These experiments simulate conditions in space or on an early Earth fluxed by protons from the solar wind, potentially mimicking a plausible prebiotic phosphorylation scenario. [ABSTRACT FROM AUTHOR]

A simulation of the radiation field inside a habitable module (a diameter of 6 m and length of 12 m) of a spacecraft generated by isotropic Galactic Cosmic Radiation (GCR) in deep interplanetary space is carried out for minimum and maximum solar activity using the FLUKA code. Protons, alpha-particles, deuterons, 3 He, and nuclei with Z > 2 are considered as primary GCR irradiating the spacecraft isotropically. The following particles are included in FLUKA radiation transport through the module shell ( 15 g/cm 2 of Al): protons, neutrons, γ -rays, electrons, π ± -mesons, μ ± -mesons d, t, and nuclei from He to Ni. The inner particle spectra are needed to assess the astronaut's radiation risk in a long-term interplanetary mission. [ABSTRACT FROM AUTHOR]

Ecotoxicity of nanoparticles (50–100 nm) of Cu, Ni, and Zn has been assessed by changes in biological indicators of an ordinary chernozem (Haplic Chernozem (Loamic)) of Rostov-on-Don in the laboratory model experiment with incubation of soil samples with nanopowders of these elements added to soil in concentrations 100, 1000, and 10 000 mg/kg. The effects of biological indicators have been determined 10, 30, and 90 days after soil contamination. The addition of Cu, Ni, and Zn nanoparticles led to a decrease of the total number of bacteria, abundance of Azotobacter bacteria, catalase and dehydrogenase activities, and germination and length of roots of radish sown. Reliable cases of hormesis were not detected. Nanoparticles of Cu and Zn showed higher toxicity than Ni nanoparticles, and this was inconsistent with the hypothesis, according to which the toxicity of nanoparticles depended only on their size and did not depend on chemical nature of the element. According to the integral indicator of biological state of soil, maximal toxicity of Cu, Ni, and Zn nanoparticles was observed on the 30th day after contamination. [ABSTRACT FROM AUTHOR]

The induction and repair of DNA double-strand breaks in hippocampal formation after exposure to accelerated 78Kr ions with an energy of 2.58 GeV/nucleon has been studied using the immunohistochemical staining of rat-brain paraffin sections with antibodies specific to γH2AX and 53BP1 proteins. Following exposure to heavy ions, complex clusters of double-strand breaks are detected in various structures of hippocampal formation. It is shown that most γH2AX/53BP1 foci are part of complex clusters (~80%) and colocalized with visualized repair proteins (~75%) along the tracks of heavy charged particles. After 24 h of postirradiation incubation, the effective elimination of radiation-induced γH2AX/53BP1 foci is observed in the cells of the dentate gyrus and the CA1 region of the hippocampal formation. In the cells of the dentate gyrus, the peak of γH2AX/53BP1 formation occurs 4 h after irradiation. [ABSTRACT FROM AUTHOR]

Experimental techniques for irradiating primate and rat brains by a narrow 78Kr beam with an energy of 2.58 GeV/n extracted from the JINR Nuclotron is described. The brain is irradiated near the F3 focal point located in the experimental hall of Building 1 of the JINR Laboratory of High-Energy Physics (LHEP). The beam profile is measured with multiwire ionization chambers and radiochromic films, and its quality is monitored using time-of-flight scintillation counters. The radiation dose absorbed by the irradiated object is measured using a dosimetric ionization chamber with tilted electrodes. This air-filled chamber has been designed so as to suppress the effect of ion column recombination in the tracks of high-Z nuclei. The extracted beam of 78Kr ions is calibrated and monitored using nuclear photoemulsions and by comparing the readings from the standard ionization chamber at the beam extraction point with the ion counting rate in scintillation counters. The experiment benefits from Nuclotron's stable operation and from the high intensity of the 78Kr beam reached in the 55th run (~2 × 106 ions per beam impulse at the F3 focal point). In this unique radiobiological experiment, the effects of the heavy ions of galactic cosmic rays on cerebral cognitive functions of astronauts are emulated and investigated. [ABSTRACT FROM AUTHOR]

This article presents first results for laboratory tests of a concept of space gamma-spectrometer with tagged protons method at the Laboratory of Nuclear Problems of JINR. There are presented results of a significant increase in the sensitivity of the gamma-ray instrument for the main rock-forming elements of celestial bodies in case of selecting spectrometer signals according to the criterion of coincidence with protons, which cause secondary gamma radiation in a thick target as an analogue of planetary matter. [ABSTRACT FROM AUTHOR]

In the model experiment, the ecotoxicity of nanoparticles (10-20 nm) and conventional (non-nano) powders (100 nm and above) of Ni and Fe oxides was compared. Their effect on microorganisms, plants and enzymatic activity of the soil was investigated as well. It was found that the microbiological indicators (the total number of bacteria and the abundance of Azotobacter) were most strongly affected by the nanoforms of Ni and Fe oxides. The enzymatic activity of the soil (the activity of catalase and dehydrogenase) was largely dependent on Ni and Fe oxides and not on their nanoparticles. The indicators of phytotoxicity (germination and length of the radish root) were influenced both by Ni and Fe oxides and their nanoforms in equal measure. Thus, nanoparticles of Ni and Fe oxides (10-20 nm) are more toxic for bacteria than particles of Ni and Fe oxides of usual sizes (100 nm and above), and vice versa for soil enzymes. A hypothesis was also tested, according to which the toxicity of metal nanoparticles does not depend on their chemical nature. For this, the effect of nanoparticles of nickel, highly toxic for biota, and low-toxic iron was compared. The addition of equal amounts of nickel and iron (from 100 to 10,000 mg/kg) had approximately the same comparable negative effect, whereas nickel is considered a significantly more toxic heavy metal than iron. [ABSTRACT FROM AUTHOR]

The effect of the DNA synthesis inhibitors 1-β-D-arabinofuranosyl cytosine (AraC) and hydroxyurea (HU)—antitumor agents used in the clinic—on the formation of DNA double-strand breaks (DSBs) in human cells after irradiation with Bragg peak protons has been studied. It is shown that in the presence of AraC and HU the biological efficiency of proton irradiation, which is estimated based on γH2AX/53BP1 foci formation kinetics, increases sharply in the post-irradiation period. This is due to the formation of enzymatic DSBs from prolonged unrepaired single-strand DNA breaks. The proposed approach significantly increases the biological effectiveness of proton beams, thereby bringing the fields of the therapeutic use of proton and carbon ion accelerators much closer to each other. [ABSTRACT FROM AUTHOR]

The construction of a dosimeter for measuring the ambient dose of neutrons with energy from 10–4 MeV to 1 GeV based on a cylindrical polyethylene moderator with lead and cadmium inserts and a 3He counter of thermal neutrons is proposed. Numerical Monte Carlo simulations based on the GEANT4 and SHIELD programs were applied to choose the optimal design of the dosimeter and calculate its energy sensitivity function. The device can be used for operational and stationary radiation monitoring in neutron fields on high-energy accelerators. A comparison of the dosimeter characteristics with foreign analogs is given. [ABSTRACT FROM AUTHOR]

The results obtained by experimentally studying gamma rays emitted by samples prepared as analogs of planetary matter and irradiated with thermal neutrons are presented. The intensities of spectral lines of gamma rays emitted by such samples differing in chemical composition are compared. These results will be used in processing data on gamma-ray spectra of the Moon and Mercury from measurements performed onboard spacecrafts with the aim of studying the composition of the surface of these celestial bodies. [ABSTRACT FROM AUTHOR]

The results of neutron-activation measurements performed using the model of planetary soil and detectors based on high-purity germanium (HPGe) and cerium bromide (CeBr3) are reported. Gamma lines lying in the energy range from 200 keV to 8 MeV are used as indicators to compare these two types of detectors in experiments with the model irradiated by 14-MeV neutrons from a pulse neutron generator. The results will aid the design of scientific instruments for the active neutron and gamma spectroscopy of planet surfaces in future Russian and international lander missions (Luna-Glob, Luna-Resurs, and ExoMars-2020). [ABSTRACT FROM AUTHOR]

The monitoring of neutron radiation from high-energy accelerators cannot fully rely on the standard dosimeters and radiometers manufactured in Russia, since these are sensitive only to neutrons with energies below some 10 MeV. This is because neutrons of higher energies can significantly contribute to the personnel doses both close to the accelerator shield and in the neutron multiscattered field around the shield. In this paper, we propose to measure the ambient neutron dose in energy range 10-2 MeV to 1 GeV with a device consisting of two polyethylene balls with diameters of 3 and 10 in. housing slow-neutron detectors. The larger ball also comprises a lead converter (10'' + Pb). This device can be implemented in zonal radiation monitoring in the near-accelerator area. [ABSTRACT FROM AUTHOR]

The factors of increased wear of current-carrying brushes in direct-current motors designed for high-altitude operation are considered. The results of testing six motors with different degrees of airtightness are presented. It is found out that increased airtightness makes the lacquer film less resistive (thinner) and increases the brush wear. A method of decreasing the wear of current-carrying brushes at standard and high altitudes is proposed that consists in installing a DMS-140 molybdenum disulfide lubricating brush. The lubricating brush is installed in an auxiliary brush holder or in a pocket structurally connected with the current-carrying brush holder on the header runway. The effect of the collector profile material (copper, cadmium bronze, chromium bronze) on the wear of current-carrying brushes is studied, as well as the efficiency of installing lubricating brushes for standard and high-altitude operations. The effect of lubricating brushes on the performance of a 5-W motor is considered as well as the results of testing seven 5-W motors equipped with lubricating brushes in conformity with the machine and warranty service specifications. Information is given on the results of long-term storage (for 1 and 1.9 years) of four motors with different capacities equipped with lubricating brushes, as well as in thermal vacuum tests of 10-W motors under p = 10-5-10-6 mm Hg. [ABSTRACT FROM AUTHOR]

An approach was proposed to create the technology for TIG welding of structure elements of complex geometric shapes of stainless steel using a adaptive robotic system, which allows adapting to changes in the surface shape of workpieces during welding process and minimizing the probability of arising the defected welded joints and temper colors on the workpiece surface. The technology of robotic non-consumable electrode welding of fillet joint of thin-sheet structure elements of stainless steel of AiSi 304, 210, 430 grades with a thickness of joined sheets from 0.8 to 1.5 mm was developed. The results of welding experiments showed that the developed algorithms of interaction between technical means of adaptation can be used in automatic control systems for TIG welding process. 5 Ref., 2 Tables, 10 Figures. [ABSTRACT FROM AUTHOR]

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The influence of parameters, determining the different duration of electrodynamic effect on reduction of level of residual stresses in welds of butt joints of aluminium alloy AMg6 as a result of electrodynamic treatment, was investigated. It is shown that the increase in electrodynamic effect duration, attained by the increase in inductance of a discharge circuit at constant amplitude values of a pulsed electric current, is characterized by a higher increase in time of current decay as compared with the period of its growing. At the same time, the increase in duration of electrodynamic effect leads to the increase in the method efficiency for reducing the level of residual stresses in welded joints of AMg6 alloy. It is noted that at the duration of t ≥ 0.7ms the reduction in stresses is determined by the electromagnetic effect intensity and Joule heating of the plate surface. [ABSTRACT FROM AUTHOR]

Liquid formamide has been irradiated by high-energy proton beams in the presence of powdered meteorites, and the products of the catalyzed resulting syntheses were analyzed by mass spectrometry. Relative to the controls (no radiation, or no formamide, or no catalyst), an extremely rich, variegate, and prebiotically relevant panel of compounds was observed. The meteorites tested were representative of the four major classes: iron, stony iron, chondrites, and achondrites. The products obtained were amino acids, carboxylic acids, nucleobases, sugars, and, most notably, four nucleosides: cytidine, uridine, adenosine, and thymidine. In accordance with theoretical studies, the detection of HCN oligomers suggests the occurrence of mechanisms based on the generation of radical cyanide species (CN.) for the synthesis of nucleobases. Given that many of the compounds obtained are key components of extant organisms, these observations contribute to outline plausible exogenous high-energy-based prebiotic scenarios and their possible boundary conditions, as discussed. [ABSTRACT FROM AUTHOR]

Presented are the results of complex of carried out investigations on development of technology for welding by penetration welds of stringer panels of titanium alloy VT20 providing minimum residual stresses and deformations and also high values of their life at cyclic loads. On the full-scale specimens, simulating stringer panels, the penetration welds of T-joints were produced using three methods: electron beam, automatic argon-arc nonconsumable-electrode welding over the layer of activating flux, and automatic argon-arc nonconsumable-electrode welding with immersed arc. To prevent the residual welding stresses and deformations, preliminary elastic deformation of elements being welded was applied. The fatigue tests of all the types of specimens at longitudinal cyclic tension were carried out. The effect of heat treatment, impact mechanical treatment and repair-welding technologies on their fatigue life was also determined. Basing on the results of investigations of full-scale specimens the batches of stringer panels of 1200 mm length were manufactured and tested. The penetration welds, made by argon arc non-consumable electrode welding over the layer of activating flux using preliminary elastic deformation and high-frequency mechanical peening of welds, provide the higher values of fatigue life of welded stringer panels of high-strength titanium alloy VT20 as compared to electron beam welding and argon arc non-consumable electrode welding with immersed arc. The developed technology can be accepted for industrial production of welded stringer panels of high-strength titanium alloys. [ABSTRACT FROM AUTHOR]

Rats were irradiated with carbon ions ( 12C) in a Nuklotron accelerator. The irradiation dose was 1 Gy, the energy of the ions was 500 MeV/nuclon, and the linear energy transmission (LET) was 10.6 keV/micron. The animals were decapitated 1 day after irradiation. We isolated the prefrontal cortex, nucleus accumbens, hypothalamus, hippocampus, and striatum, where we determined the concentrations of monoamines and their metabolites. Strong changes were observed in three structures, viz., the prefrontal cortex, nucleus accumbens, and hippocampus. However, significant changes were found in the prefrontal cortex and weaker changes were seen in the nucleus accumbens, whereas changes were insignificant in the hippocampus. This reaction may be related to the fact that the animals were examined on the 2nd day after irradiation. It was shown that an increase in the interval between irradiation and examination of animals results in enhancement of the effects of radiation treatment. The experiments revealed the high sensitivity and reactivity of the prefrontal cortex, which we relate to the key role of this structure in vitally critical processes of behavior. [ABSTRACT FROM AUTHOR]

At the present time the methods of control of welded and technological stresses based on preliminary deforming of elements being welded and also electrodynamic treatment (EDT) of welds using pulsed current become ever more developed. The aim of the work is the investigation of influence of preliminary unclamping of edges being welded and EDT on control of stressed state of circumferential welded joints specimens of aluminium alloy AMg6, made using automatic welding in argon. Control of stressed state of specimens was performed using method of electron speckle-interferometry with use of a specialized rigging. The preliminary unclamping of edges was performed using original device for force loading. The values of preliminary tensile stresses reached the yield strength of AMg6 alloy. The EDT was conducted at the surface of deposited metal in the direction «from middle to edges» at a charged voltage of capacitive storage up to 450 V. As a result of carried out investigations it was established that preliminary unclamping and EDT allow significant decreasing of level of residual stresses in circumferential welded joints. [ABSTRACT FROM AUTHOR]

Background. In electric arc furnaces (EAF) of high capacity water cooled elements (panels) are often used, with the heat loss of about 12...15 % of the energy input. The double-row energy-saving panels have been suggested. However, there are no experimental data on their efficiency. The aim of the work is to estimate the heat loss of EAF during the use of traditional single-row and double-row wall panels. Materials and/or methods. The estimation of the heat loss with the cooling water has been carried out on two high-capacity EAFs with the similar characteristics, equipped with single-row and double-row panels. The technique was to calculate the heat loss in wall panels in the most heat-stressed melting period - just before steel discharge on the basis of the registered parameters: water rate and temperature difference. In the comparative analysis of heat loss with water there have been made assumptions that reduced (for the conditions of engineering calculation) all radiates in the smelting room of EAF to the main two: liquid bath and side surface of graphitized electrodes. Results. Based on the measured parameters and made assumptions, after reducing the heat loss capacities with cooling water to the same conditions, taking into account the geometry of the furnace and radiation laws the estimation of energy efficiency of EAF within the set task has been carried out. Conclusion. It has been shown experimentally that the reduction of EAF energy consumption with the replacement of the traditional single-row panels by double-row ones makes 3 kW/h per tonne of steel at the expense of the decrease of heat loss by the cooling water. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the distribution of chromosomal aberrations in chromosomes 2, 8 and 14 induced by charged particles, using the fluorescence in situ hybridisation (FISH) technique. Methods: Irradiation of peripheral blood from six healthy volunteers (four male and two female) was performed at the accelerators of the Joint Institute for Nuclear Research (JINR) in Dubna (Russia). Whole blood samples were irradiated with 2 and 3 Gy of protons (170 MeV/nucleon (n), linear energy transfer (LET) ≈ 0.5 keV/μm), 3.5 Gy of 12C ions (480 MeV/n, LET = 10.6 keV/μm), 3 Gy of 12C ions 500 MeV/n, LET = 12 keV/μm), 4 Gy of 7Li ions (30 MeV/n, LET ≈ 20 keV/μm) and 3 Gy of 11B ions (32 MeV/n, LET ≈ 55 keV/μm). Chromosomal aberrations were analysed in metaphase and prematurely condensed chromosomes (PCC) induced in G2-cells using calyculin A. Chromosomes 2, 8 and 14 were painted in different colours and aberrations scored with the help of an image-analysis system. Results: Chromosome 2 was generally less sensitive than expected on the basis of its DNA content. A higher than expected frequency of exchanges was found in chromosomes 8 and 14. On average, the dicentric frequency in chromosome 2 was higher than the translocation frequency, whereas variable dicentric to translocation ratios were observed in chromosomes 8 and 14. When aberrations in all painted chromosomes were summed up the ratio was close to 1. The frequency of complex aberrations correlated with LET. Conclusion: In lymphocytes of donors studied in this work chromosome 2 appears to be consistently less sensitive to protons and heavy ions than chromosomes 8 and 14. Complex aberrations appear to be a potential marker of radiation quality. [ABSTRACT FROM AUTHOR]

An attempt is made to establish a correlation between the radial and axial growth rates and the change in the conditions of heat transfer from a growing crystal to the atmosphere of the water-cooled vacuum furnace for the growth of large alkali halide single crystals. It is found experimentally that an increase in the growth rate leads to an increase in the automatic compensation of the melt temperature by the main heater. In this case, the thickness of the layer of melt condensate on the end face and the lateral surface of the crystal decreases. It is revealed that the possibility of growing infinitely long ingots in the presence of intense melt evaporation is restricted by the possibilities of the heat transport through the boundary between the furnace atmosphere and the cooled furnace walls, onto which melt condensate deposits. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]