Kassym Zhumadilov | The L.N. Gumilyov Eurasian National University (original) (raw)

Papers by Kassym Zhumadilov

Ceramics, 2021

The work is devoted to the study of radiation damage and subsequent swelling processes of the sur... more The work is devoted to the study of radiation damage and subsequent swelling processes of the surface layer of Li2ZrO3 ceramics under irradiation with heavy Xe22+ ions, depending on the accumulation of the radiation dose. The samples under study were obtained using a mechanochemical synthesis method. The samples were irradiated with heavy Xe22+ ions with an energy of 230 MeV at irradiation fluences of 1011–1016 ion/cm2. The choice of ion types is due to the possibility of simulating the radiation damage accumulation processes as a result of the implantation of Xe22+ ions and subsequent atomic displacements. It was found that, at irradiation doses above 5 × 1014 ion/cm2, point defects accumulate, which leads to a disordering of the surface layer and a subsequent decrease in the strength and hardness of ceramics. At the same time, the main process influencing the decrease in resistance to radiation damage is the crystal structure swelling as a result of the accumulation of defects and...

No evidence for the TRI-effect in the gray and neutron emission so far. No evidence for the TRI-e... more No evidence for the TRI-effect in the gray and neutron emission so far. No evidence for the TRI-effect in the gray and neutron emission so far. Historical background (II)

7 Graduated School 0/ Engineering. Hiroshima University. Japan 'Center 0/ Medical Education. ... more 7 Graduated School 0/ Engineering. Hiroshima University. Japan 'Center 0/ Medical Education. Sapporo Medical University, Japan 'School 0/ Dentistry. Ohu University. Koriyama-shi. Japan 10 Low Level Radioactivity Laboratory. K-INET, Kanazawa University, Japan " Graduate School 0/ Biomedical Sciences, Hiroshima University. Japan The method of electron spin resonance (ESR) dosimetry was used to human tooth enamel to obtain individual absorbed doses of population of settlements in the vicinity of the Semipalatinsk Nuclear Test Site (SNTS), Kazakhstan. The distances between investigated settlements and Ground Zero (SNTS) are in the range 70 200 km from SNTS. Most of settlements (Dol on, Mostik, Bodene) are located near the central axis of radioactive fallout trace from the most contaminating surface nuclear test, which was conducted in 29, August 1949. The other settlements located close to radioactive fallout trace as a result of surface nuclear tests in 24, August 1956 (Us...

Scientific Reports, 2021

To understand the radiation effects of the atomic bombing of Hiroshima and Nagasaki among the sur... more To understand the radiation effects of the atomic bombing of Hiroshima and Nagasaki among the survivors, radiation from neutron-induced radioisotopes in soil should be considered in addition to the initial radiation directly received from the bombs. 56Mn, which emits both β particles and γ-rays, is one of the dominant radioisotopes created in soil by neutrons from the bomb. Thus we investigated the biological effects of internal exposure to 56MnO2 particle in the lung of male Wistar rats comparing to the effects of external 60Co-γ irradiation. Absorbed doses of internal irradiation of lungs were between 25 and 65 mGy in 56MnO2-exposed animals, while the whole body doses were between 41 and 100 mGy. Animals were examined on days 3 and 61 after the exposure. There were no remarkable pathological changes related to 56MnO2 particle exposure. However, mRNA and protein expressions of aquaporin 5 increased significantly in the lung tissue on day 3 postexposure in 56MnO2 groups (by 1.6 and ...

Radiation and Environmental Biophysics, 2020

The experiment was performed in support of a Japanese initiative to investigate the biological ef... more The experiment was performed in support of a Japanese initiative to investigate the biological effects of irradiation from residual neutron-activated radioactivity that resulted from the A-bombing. Radionuclide 56Mn (T1/2 = 2.58 h) is one of the main neutron-activated emitters during the first hours after neutron activation of soil dust particles. In our previous studies (2016–2017) related to irradiation of male Wistar rats after dispersion of 56MnO2 powder, the internal doses in rats were found to be very inhomogeneous: distribution of doses among different organs ranged from 1.3 Gy in small intestine to less than 0.0015 Gy in some of the other organs. Internal doses in the lungs ranged from 0.03 to 0.1 Gy. The essential pathological changes were found in lung tissue of rats despite a low level of irradiation. In the present study, the dosimetry investigations were extended: internal doses in experimental mice and rats were estimated for various activity levels of dispersed neutro...

International Journal of Molecular Sciences, 2020

To investigate the biological effects of internal exposure of radioactive 56MnO2 powder, the majo... more To investigate the biological effects of internal exposure of radioactive 56MnO2 powder, the major radioisotope dust in the soil after atomic bomb explosions, on male reproductive function, the gene expression of the testes and the prostate was examined. Ten-week-old male Wistar rats were exposed to three doses of radioactive 56MnO2 powder (41–100 mGy in whole body doses), stable MnO2 powder, or external 60Co γ-rays (2 Gy). Animals were necropsied on Days 3 and 61 postexposure. The mRNA expressions of testicular marker protein genes and prostatic secretory protein genes were quantified by Q-RT-PCR. On Day 3 postexposure, the testicular gene expressions of steroidogenesis-related enzymes, Cyp17a1 and Hsd3b1, decreased in 56MnO2-exposed groups. Germ cell-specific Spag4 and Zpbp mRNA levels were also reduced. On postexposure Day 61, the Cyp11a1 gene expression became significantly reduced in the testes in the group exposed to the highest dose of 56MnO2, while another steroidogenesis-re...

Radiation Measurements, 2020

Abstract The measurement of teeth in vivo (i.e., in the mouth, without extraction) with EPR spect... more Abstract The measurement of teeth in vivo (i.e., in the mouth, without extraction) with EPR spectroscopy in the L-band would allow to screen large groups of population in an event of an acute radiation exposure and in routine epidemiological studies. The radiation dose is proportional to intensity of the radiation-induced signal amplitude determined after subtraction of both native and solar light induced signal amplitudes from the total signal amplitude measured in L-band. Therefore, to improve the dose assessments of in vivo tooth dosimetry a better accuracy of native background signal is necessary. In this work, we present a search for the optimal machine learning approach for predicting of intensity of the native signal amplitude. The study used the dataset from two institutes composed of 1800 EPR spectra which were recorded in the X-band at a large-scale examination of the population of the Central Russia and North Kazakhstan. To determine the relevance of 12 various features a preliminary statistical significance analysis was used. Predictive models for native signal amplitude determination were developed and trained using standard Python frameworks for machine learning and data processing. The employed algorithms included 8 most popular machine learning regressors. To tune the performance of each algorithm a common evaluation technique, namely cross-validation, was used. Finally, mean squared error and coefficient of determination were calculated for performance analysis of the employed models. Comparison among the performance of all established prediction models revealed that Random Forest and Gradient Boosting had most superior performance. Overall, the application of machine learning methods was shown to provide a minor (5–11% in terms of R2) but non negligible improvement to the accuracy of native signal amplitude prediction. Using the technique of adding synthetic noise variables, the most significant factor regarding the prediction was position of tooth in the quadrant.

E3S Web of Conferences, 2017

Bulletin of the Karaganda University. "Physics" Series, 2019

Radiation and Environmental Biophysics, 2017

Radiation and Environmental Biophysics, 2014

The aim of this pilot study was to evaluate possible doses in teeth received by workers of a uran... more The aim of this pilot study was to evaluate possible doses in teeth received by workers of a uranium processing plant, in excess to the natural background dose. For this, the electron paramagnetic resonance dosimetry method was applied. Absorbed doses in teeth from the workers were compared with those measured in teeth from the Stepnogorsk city population and a control pool population from Astana city. The measured tooth samples were extracted according to medical indications. In total, 32 tooth enamel samples were analyzed, 5 from Astana city, Kazakhstan (control population), 21 from the residents of Stepnogorsk city (180 km from Astana city), and 6 from the workers of a uranium processing plant. The estimated doses in tooth enamel from the uranium processing plant workers were not significantly different to those measured in enamel from the control population. In teeth from the workers, the maximum dose in excess to background dose was 33 mGy. In two teeth from residents of Stepnogorsk city, however, somewhat larger doses were measured. The results of this pilot study encourage further investigations in an effort to receiving a final conclusion on the exposure situation of the uranium processing plant workers and the residents of Stepnogorsk city.

Science of The Total Environment, 2010

The first results on the feasibility of using (236)U to reconstruct the level and spatial distrib... more The first results on the feasibility of using (236)U to reconstruct the level and spatial distribution of close-in fallout deposition from the Hiroshima A-bomb are reported, coupled with the use of global fallout (137)Cs and (239+240)Pu. The results for global fallout (236)U in soil samples (0-30cm) from Ishikawa prefecture showed that the deposition density of (236)U from the global fallout can be accurately evaluated using AMS. All deposited (236)U, (137)Cs and (239+240)Pu appeared to have been recovered using 30-cm cores. It was also noted from the depth profiles for (236)U/(239+240)Pu and (236)U/(137)Cs ratios that the downward behavior of (236)U in the soil was apparently similar to that of (239+240)Pu, while the (137)Cs was liable to be retained in upper layers compared with (236)U and (239+240)Pu. The accumulated levels were 1.78×10(13)atomsm(-2) for (236)U, 4340Bqm(-2) for (137)Cs and 141Bqm(-2) for (239+240)Pu. The ratios of (236)U/(137)Cs and (236)U/(239+240)Pu were (4.10±0.12)×10(9) and (1.26±0.04)×10(11)atomsBq(-1), respectively. Results of (236)U, (137)Cs and (239+240)Pu measurements for the seven soil cores (0-30cm) from Hiroshima were discussed on the basis of ratios of (236)U/(137)Cs and (236)U/(239+240)Pu by comparing with those from the background area in Ishikawa, indicating that the global fallout dominates the current level of (236)U accumulation in soil in the Black-rain area around Hiroshima after the Hiroshima bomb, and the contribution of the close-in fallout (236)U produced by the Hiroshima A-bomb seems difficult to observe.

Radiation Measurements, 2007

Radiation Measurements, 2011

The method of electron spin resonance (ESR) dosimetry has been applied to human tooth enamel in o... more The method of electron spin resonance (ESR) dosimetry has been applied to human tooth enamel in order to obtain individual absorbed doses from the population of settlements within the vicinity of the central axis of the radioactive fallout trace from the contaminating nuclear surface test of 24, August 1956. Most of the settlements (Glubokoe, Tavriya, and Gagarino) are located near