Practical work results on the development of an experimental stand for wear tests of millstones for grinding of grain are presented. When designing the stand, the method of testing for abrasive wear ...during friction against loosely fixed abrasive particles was used. A feature of the test bench is that the movable and fixed millstones are made cone-shaped and during testing are in oscillatory motion relative to the stationary stand platform. The test bench is equipped with a drive shaft speed sensor, a temperature sensor and a strain gauge force sensor. The Arduino IDE microcontroller software is used to process the incoming data. The software allows one to display the current values of the measured parameters on the screen of a personal computer monitor. All data are saved to files for further processing, which significantly reduces the time for experimental studies.
The paper considers the possibility of the recovery of fast wearing parts of process equipment of beet sugar plants and provides a brief description of the recovering technology of these parts by ...plasma spraying with coating fusing. Technological parameters of plasma spraying with fusing of wear-resistant coatings are considered. On the base of the research work the Engineering Guidelines of recovery of fast wearing parts of process equipment of beet sugar plant by plasma spraying with fusing is provided.
Polar regions are the most exposed to secondary particles and radiation produced by primary cosmic rays in the atmosphere, because naturally they are with marginal geomagnetic shielding. In addition, ...the secondary particle flux contributing to the complex radiation field is enhanced at high-mountain altitudes compared to sea level because of the reduced atmospheric attenuation. At present, there are very few systematic experimental measurements of environmental dose at high southern latitudes, specifically at high-altitude region. Here, we report a campaign of measurements with different devices, that is passive and Liulin-type dosimeters, of the radiation background at high-mountain Antarctic station Vostok (3488 m above sea level, 78° 27′ S; 106° 50′ E). We compare the measurements with a Monte Carlo-based model for the propagation of the cosmic rays through the atmosphere and assessment of the radiation field in the atmosphere. We employed the model to estimate the radiation dose at Vostok station during the ground-level enhancement at 28 October 2021. As in previous studies by other teams, we show that the annual dose equivalent at high-altitude Antarctic facilities can significantly exceed the limit of 1 mSv established for the general population by the ICRP.
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•Measurement of radiation background at high-altitude Antarctic station Vostok•Comparison with model for propagation of the cosmic rays through the atmosphere•Assessment of the contribution of cosmic rays to radiation during solar proton event•The dose at high-altitude Antarctic stations significantly exceeds the limit of 1 mSv.
•Computational prediction of antibacterial activity.•Similarity assessment.•Antibacterial activity evaluation.•Docking to antibacterial targets.
Griseofulvin is a well-known antifungal drug that was ...launched in 1962 by Merck & Co. for the treatment of dermatophyte infections. However, according to predictions using the Way2Drug computational drug repurposing platform, it may also have antibacterial activity. As no confirmation of this prediction was found in the published literature, this study estimated in-silico antibacterial activity for 42 griseofulvin derivatives. Antibacterial activity was predicted for 33 of the 42 compounds, which led to the conclusion that this activity might be considered as typical for this chemical series. Therefore, experimental testing of antibacterial activity was performed on a panel of Gram-positive and Gram-negative micro-organisms. Antibacterial activity was evaluated using the microdilution method detecting the minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC). The tested compounds exhibited potent antibacterial activity against all the studied bacteria, with MIC and MBC values ranging from 0.0037 to 0.04 mg/mL and from 0.01 to 0.16 mg/mL, respectively. Activity was 2.5–12 times greater than that of ampicillin and 2–8 times greater than that of streptomycin, which were used as the reference drugs. Similarity analysis for all 42 compounds with the (approximately) 470,000 drug-like compounds indexed in the Clarivate Analytics Integrity database confirmed the significant novelty of the antibacterial activity for the compounds from this chemical class. Therefore, this study demonstrated that by using computer-aided prediction of biological activity spectra for a particular chemical series, it is possible to identify typical biological activities which may be used for discovery of new applications (e.g. drug repurposing).
Forty two griseofulvin derivates were evaluated for their antibacterial activity based on the predictions using Way2Drug computational drug repurposing platform, according to which it may have antibacterial activity. Docking studies were perform to find possible mechanism of antibacterial activity. Display omitted
•Poloidal system of IGNITOR tokamak was improved by introducing two new coils: HFC and VFC•Location of HFC was optimized to achieve the maximal controllability region in vertical direction•Location ...of VFC was optimized to achieve maximal plasma position response to voltage step function•New robust decentralized plasma position control systems were designed for improved poloidal system•New control systems were simulated with thyristor rectifiers and voltage inverters in PWM mode as actuators
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The paper deals with the improvement of the poloidal system of the IGNITOR tokamak, and the design and simulation of the robust decentralised control systems of the plasma’s vertical and horizontal position. The results were obtained on a linear model that is constructed from the circuit equations for the coils, plasma, and vacuum vessel (VV) currents, and from the force balance equations for the plasma. Two new coils that are located close to the VV have been introduced in the IGNITOR poloidal system; specifically, a Horizontal Field Coil (HFC) that is designated for the plasma vertical position control and a Vertical Field Coil (VFC) that is used for the horizontal position control. For the first time in the design of D-shaped tokamaks poloidal systems, the location of the HFC was optimised to achieve the maximum size of the plasma controllability region in the vertical direction and the location of the VFC was determined from the optimisation of the plasma position response to the voltage step function. Although the ideal position of the VFC with fast response time is on the equatorial plane, its location usually is occupied by the other devices such as ports, diagnostic system, and heating systems, so the separated two-section VFC is used. Careful calculation shows the performance is degraded by only 20 % in this layout. For the improved IGNITOR poloidal system, the new robust decentralised plasma position control systems were designed by means of two robust approaches: H∞-optimisation and Linear Matrix Inequalities (LMI). The results of the simulation of the control systems with two types of actuator models as the multiphase thyristor rectifier and the voltage inverter in Pulse- Width Modulation (PWM) mode for the new IGNITOR poloidal system are presented.
•Dose reduction effect for space radiation by water shielding material was verified.•Absorbed dose and dose equivalent were evaluated with passive dosimeters.•Observed dose reduction rate was found ...to be 37±7% in dose equivalent.•It will effectively reduce the annual dose for space crews and long-term mission.
The dose reduction effects for space radiation by installation of water shielding material (“protective curtain”) of a stack board consisting of the hygienic wipes and towels have been experimentally evaluated in the International Space Station by using passive dosimeters. The averaged water thickness of the protective curtain was 6.3g/cm2. The passive dosimeters consisted of a combination of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs). Totally 12 passive dosimeter packages were installed in the Russian Service Module during late 2010. Half of the packages were located at the protective curtain surface and the other half were at the crew cabin wall behind or aside the protective curtain. The mean absorbed dose and dose equivalent rates are measured to be 327μGy/day and 821μSv/day for the unprotected packages and 224μGy/day and 575μSv/day for the protected packages, respectively. The observed dose reduction rate with protective curtain was found to be 37±7% in dose equivalent, which was consistent with the calculation in the spherical water phantom by PHITS. The contributions due to low and high LET particles were found to be comparable in observed dose reduction rate. The protective curtain would be effective shielding material for not only trapped particles (several 10MeV) but also for low energy galactic cosmic rays (several 100MeV/n). The properly utilized protective curtain will effectively reduce the radiation dose for crew living in space station and prolong long-term mission in the future.
The paper presents the results of the calculation of cosmic ionizing radiation doses for conditions that simulate
ISS
crew quarters outfitted with additional protection in the form of a “protective ...shutter” kit used in the Matryoshka-R experiment; the kit is filled with high-pressure polyethylene instead of regular means of cosmonaut personal hygiene (wet wipes and towels). The calculation was performed using the ray tracing method, which was previously verified using the experimental data on the dose loads in the space station sections. The protective shutter kit has a thickness of 10 cm and covers the exterior wall of the crew quarters; its volume is filled with high-pressure polyethylene. The calculation is performed for the locations of experimental dosimetric assemblies for typical
ISS
orbits in the phase of minimum and maximum solar activity. The effect from the use of the additional protection (AP) in the
ISS
crew quarters in terms of the equivalent dose varies between 22 and 60% depending on the orbital altitude, phase of solar activity cycle, and initial conditions of protection. The results indicate a higher efficiency of the additional protection of polyethylene in comparison with water-containing materials. This AP from cosmic radiation has the potential to be used in long-term and long-range spaceflights.
A description of the detection and data-acquisition systems of the Cherenkov water calorimeter of the NEVOD Experimental Complex, which is a unique scientific facility located on the Earth’s surface, ...is presented. In the development of these systems, a solution is sought to the problem of measuring the energy of cascade showers initiated by single muons and the energy deposited by high-multiplicity muon bundles in a wide energy range.
To estimate the radiation risk of astronauts during space missions, it is necessary to measure dose characteristics in various compartments of the spacecraft; this knowledge can be further used for ...estimating the health hazard in planned missions. This contribution presents results obtained during several missions on board the International Space Station (ISS) during 2005-09. A combination of thermoluminescent and plastic nuclear track detectors was used to measure the absorbed dose and dose equivalent. These passive detectors have several advantages, especially small dimensions, which enabled their placement at various locations in different compartments inside the ISS or inside the phantom. Variation of dosimetric quantities with the phase of the solar cycle and the position inside the ISS is discussed.
Space radiation is known to be key hazard of manned space mission. To estimate accurately radiation health risk detailed study of dose distribution inside human body by means of human phantom is ...conducted. In the space experiment MATROSHKA-R, the tissue-equivalent spherical phantom (32 kg mass, 35 cm diameter and 10 cm central spherical cave) made in Russia has been used on board the ISS for more than 8 years. Owing to the specially chosen phantom shape and size, the chord length distributions of the detector locations are attributed to self-shielding properties of the critical organs in a real human body. If compared with the anthropomorphic phantom Rando used inside and outside the ISS, the spherical phantom has lower mass, smaller size and requires less crew time for the detector installation/retrieval; its tissue-equivalent properties are closer to the standard human body tissue than the Rando-phantom material. Originally the spherical phantom was installed in the star board crew cabin of the ISS Service Module, then in the Piers-1, MIM-2 and MIM-1 modules of the ISS Russian segment, and finally in JAXA Kibo module. Total duration of the detector exposure is more than 1700 days in 8 sessions.
In the first phase of the experiment with the spherical phantom, the dose measurements were realized with only passive detectors (thermoluminescent and solid-state track detectors). The detectors are placed inside the phantom along the axes of 20 containers and on the phantom outer surface in 32 pockets of the phantom jacket. After each session the passive detectors are returned to the ground. The results obtained show the dose difference on the phantom surface as much as a factor of 2, the highest dose being observed close to the outer wall of the compartment, and the lowest dose being in the opposite location along the phantom diameter. Maximum dose rate measured in the phantom is obviously due to the galactic cosmic ray (GCR) and Earth' radiation belt contribution on the ISS trajectory. Minimum dose rate is caused mainly by the strongly penetrating GCR particles and is observed behind more than 5 g/cm2 tissue shielding. Critical organ doses, mean-tissue and effective doses of a crew member in the ISS compartments are also estimated with the spherical phantom data. The estimated effective dose rate is found to be from 10 to 15% lower than the averaged dose on the phantom surface as dependent on the attitude of the critical organs.
The spherical phantom proved its effectiveness to measure the critical organ doses together with the effective dose in-flight and if supplied with active dosimeters can be recommended for future exploratory manned missions to monitor continuously the effective dose.
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