Hasil untuk "Radioactivity and radioactive substances"

Iqbal Hossen, M. Mehedi Hasan Rocky, Zinnat Rahman et al.

Khaled Ali, A. E. Abbady, Ahmed Abu-Taleb et al.

This study investigates the distribution, transfer, and potential ecological risks of naturally occurring radioactive materials, including radon-222 (222Rn), radium-226 (226Ra), thorium-232 (232Th), and potassium-40 (40K), in the aquatic ecosystem of Nasser Lake, Egypt. As Egypt’s largest freshwater reservoir and a critical source of drinking water and fish, Nasser Lake plays a key role in environmental stability and public health. A total of 40 environmental samples—sediment, water, aquatic plants, and fish—were collected from 10 strategically selected sites around the lake. Gamma spectroscopy using sodium iodide activated with thallium [NaI(Tl)] detectors and AlphaGUARD radon monitoring systems was employed to measure radionuclide activity concentrations. Spatial distribution patterns were analyzed using Geographic Information System (GIS) techniques to identify zones of elevated radioactivity. The highest concentrations of 226Ra, 232Th and 40K were recorded in sediment samples near the High Dam, reaching 10.99 ± 0.42 Bq kg−1, 23.94 ± 1.91 Bq kg−1, and 277.38 ± 23.86 Bq kg−1, respectively. A strong positive correlation (Pearson’s r = 0.913) was observed between 226Ra and 222Rn exhalation rates, confirming that sediment accumulation significantly contributes to local radiological emissions. Bioaccumulation studies showed progressive uptake of radionuclides along the aquatic food chain, with fish exhibiting a bioaccumulation factor (BAF) of 0.74 for 226Ra. Estimated annual radiation doses from fish consumption reached up to 6.435 microsieverts per year (µSv y−1), remaining below international reference levels established by the World Health Organization (WHO). However, the combination of localized contamination near the High Dam and high fish consumption in nearby communities may present long-term radiological exposure risks. These findings highlight the importance of continuous monitoring of radioactive contaminants in sediment, water, and aquatic organisms in Nasser Lake. The study also provides a transferable framework for assessing the behavior of technologically enhanced naturally occurring radioactive materials (TENORM) in freshwater environments and supports the goals of the United Nations Sustainable Development Goals (SDGs) for clean water and good health.

ALESSANDRO A. JORDÃO, Valter Arthur

The growing recognition of university-industry collaborations as a strategic alternative for economic and social development at regional and national levels has fostered a continuous academic (and political) debate. Moreover, university-industry collaboration emerges as a strategic pathway for research production, particularly in developing and emerging countries. However, there is a scarcity of studies on university-industry collaboration oriented towards research production, as well as on its respective impacts, especially economic and social ones. To help fill this gap, this research examined the dynamics of research collaboration of the National Nuclear Energy Commission (CNEN), as well as its respective scientific, economic, and social impacts over the past three decades – the longest available data series, which adds originality and novelty to the research. Based on a descriptive and evaluative informetric analysis of internationally indexed publications in the Scopus (Elsevier) database, accessed through the SciVal platform, it was found that publications co-authored by CNEN with industry, government, and international actors, although less frequent, achieved greater resonance and influence in international knowledge networks, attracted more attention and interest from the international community, significantly exceeding the average expectation for similar publications, and exerted a more significant influence on patentable technologies and public policy formulation. These results may be useful for informing policies, guiding pathways to increase the prolificacy and impact of research.

Miguel Duarte, Thye Choo, Karina Gonçalves et al.

The growing demand for renewable energy sources and the continuous increase in global energy demand are responsible for the need to develop new forms of energy storage. In this context, supercapacitors emerged due to properties, such as high charge density, long durability and reduced environmental impact. This work aims to develop electrodes based on cobalt oxide synthesized by ionizing radiation for use in supercapacitors. Synthesis by ionizing radiation consists of a sustainable and ecological approach to the production of nanoparticles, reducing the need for toxic reagents and high temperatures. Cobalt oxide nanoparticles were synthesized by irradiating a solution of cobalt acetate, followed by vacuum filtration and drying. The electrochemical properties of the material were evaluated using cyclic voltammetry in 1 M KOH. The results indicated that the cobalt oxide electrodes have a significant energy storage capacity, indicating their potential for use in supercapacitors.

Dhvanil D. Desai, Colby C. Haggerty, Benjamin J. Shappee et al.

The light curves of radioactive transients, such as supernovae and kilonovae, are powered by the decay of radioisotopes, which release high-energy leptons through $β^+$ and $β^-$ decays. These leptons deposit energy into the expanding ejecta. As the ejecta density decreases during expansion, the plasma becomes collisionless, with particle motion governed by electromagnetic forces. In such environments, strong or turbulent magnetic fields are thought to confine particles, though the origin of these fields and the confinement mechanism have remained unclear. Using fully kinetic particle-in-cell (PIC) simulations, we demonstrate that plasma instabilities can naturally confine high-energy leptons. These leptons generate magnetic fields through plasma streaming instabilities, even in the absence of pre-existing fields. The self-generated magnetic fields slow lepton diffusion, enabling confinement and transferring energy to thermal electrons and ions. Our results naturally explain the positron trapping inferred from late-time observations of thermonuclear and core-collapse supernovae. Furthermore, they suggest potential implications for electron dynamics in the ejecta of kilonovae. We also estimate synchrotron radio luminosities from positrons for Type Ia supernovae and find that such emission could only be detectable with next-generation radio observatories from a Galactic or local-group supernova in an environment without any circumstellar material.

N. Imam, Amr S. El-Shamy, Ghada S. Abdelaziz et al.

In the twenty-first century, numerous forms of pollution have adversely impacted freshwater and the entire aquatic ecosystem. The higher population density in urban areas also contributes to increased releases of substances and thermal contaminants, significantly stressing the ecosystem of industrial companies. This study aimed to assess the potential pressure of industrial and municipal activities on water quality, radioactivity levels, and biological diversity, focusing on the consequences of radionuclides on periphytic diatom communities. Furthermore, the environmental impact of pollutants will be evaluated to monitor the ecological condition of the Ismailia Canal. Chemical analyses employed various instruments and methods to identify and quantify matter, with radionuclide elements measured by gamma spectrometry and diatoms counted and identified by inverted microscopy. Our results revealed that the canal was classified as excellent for irrigation, aquatic life, and drinking water based on FAO, CCME, and EWQS water quality indices, with high nutrient levels at Abu Za’baal fertilizer company. The activity concentration of 226Ra-series, 232Th-series, and 40K in the water and sediment samples for two seasons was within the guideline values, except for a few stations in the zone [B] (the industrial zone). Fertilizer samples (raw material) showed a high value of the 226Ra-series activity. Diatom community structure significantly varied across the different canal locations regarding the presence or absence of industrial activities, with no discernible variations between the study seasons. A specific variety of algal species was found to be predominant at the highest radioactive sites. Redundancy analysis (RDA) showed a significant correlation between parameters (pH, Na, TDS, PO4, SO4, SiO2, K, and CO3), radionuclides, environmental conditions, and the composition of the diatom community, especially in the area affected by industrial discharges. Moreover, the radiological hazard index in water and sediment remained below the maximum for two seasons. This research provides valuable data and information for communities and decision-makers, suggesting the strategic use of phycoremediation as a water biotreatment process to protect the valuable economic resources of the Ismailia Canal.

K. O. Avrov, S. Shatik, M. P. Samoilovich

Administration of pharmaceuticals containing radioactive isotopes and capable of specific binding to certain proteins is one of the approaches used in the treatment or diagnosis of malignant tumors. High renal accumulation of radioactive compounds after administration of radioconjugates with molecular mass less than 70 KDa is of the challenges that need to be solved. The purpose of the study was to identify the most effective approaches to reduce the accumulation of radioactivity in the kidneys after administration of radioconjugates used for diagnostic imaging and targeted therapy for cancer. Material and Methods. We conducted a literature search on the topic of the review in the electronic databases PubMed, Scopus and Web of Science from 1987 to 2023, 82 articles were used for writing the review. Results. The review presents a description of approaches used to improve the biodistribution of radioconjugates, mainly in preclinical studies. The advantages and disadvantages of such techniques have been described. Conclusion. Reducing renal radioactivity using radioconjugates of molecules with molecular masses less than 70 KDa is a challenging but achievable task. It is concluded that the use of cleavable linkers in such radioconjugates is highly promising, since this approach does not change the pharmacokinetics of such drugs. It is noted that the advantage of introducing concomitant substances compared to changing the structure of radioconjugates is a lesser dependence on the characteristics of a particular radiopharmaceutical. This approach also does not require prior work to modify the radioconjugate, but has limited efficiency.

Kazuki Ouchi, Tomoko Haraga, Kazuki Hirose et al.

BACKGROUND The Fukushima Daiichi Nuclear Power Plant accident (2011) released large amounts of radioactive substances into the environment and generated highly radioactive debris. Post-accident countermeasures are currently in the phase of fuel debris removal, which requires the analysis of radioactive contaminants in the environment and fuel. The spectra of solely β-emitting nuclides, such as 90Sr, overlap; thus, an effective method for nuclide separation is desired. Since conventional methods for high-dose sample analysis pose substantial exposure risks and generate large amounts of secondary radioactive waste, faster procedures allowing for decreased radiation emission are highly desirable. RESULTS In this study, we developed a 90Sr2+ quantitation technique based on liquid scintillation counting (LSC)-coupled capillary transient isotachophoresis (ctITP), along with two-point detection and relying on the rapid concentration, separation, and fractionation of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-complexed 90Sr2+ in a single run. The applicability of our method for the analysis of real-world samples was verified by conducting addition-recovery experiments using a seawater reference material and radioactive liquid waste obtained from the radioactive waste treatment facility at the Japan Atomic Energy Agency. The recovery determined by LSC was 95-113%, indicating successful quantitative analysis. 90Sr recovery was determined to be 90.1% from a contaminated water sample obtained from the Fukushima Daiichi Nuclear Power Plant, which was analyzed using the standard addition of 90Sr. The sensitivity (detection limit = 0.016 Bq) of the proposed method on a radioactivity basis was equal to or higher than that of the conventional method using ion exchange-LSC (0.012-0.07 Bq). SIGNIFICANCE AND NOVELTY Our method allows for the handling of high-dose radioactive samples at the microliter level and is substantially faster than conventional ion exchange protocols, whereas ctITP has not been used for practical applications due to inaccurate collection and lack of a suitable chemical system. The concentration-separation-fractionation protocol in ctITP is successful due to the existence of a rare inert Sr2+ complex and precise fractionation. This study establishes a pathway toward safer and more practical analysis of radionuclides.

Alexandre Bernardino, Izabella Souza, Thais Hauradou et al.

The determination of the reference air kerma rate (KR) with well chambers calibrated using a different model of source than desired can lead to significant errors, affecting both radiological traceability institutions and healthcare facilities. This study employs the methodology proposed by SHIPLEY et al. (2015) with the PTW T33005 well chamber model and six models of HDR brachytherapy sources (microSelectron v.1; microSelectron v.2; Flexisource; GammaMed Plus; BEBIG GI192M11; Varisource VS2000) to derive correction factors for source geometry (KSG). These factors adjust the chamber calibration factor for air kerma (NK) to the source model under measurement. The methodology relies on simulating the chamber response to sources using the Monte Carlo Method (MC), specifically utilizing the MCNPX code. Both the source and well chamber models were validated by comparing dosimetric parameters from TG-43 and simulated calibration factors (MCNK) with literature-derived reference values. The normalized KSG values, relative to the microSelectron v.1 source, agree with reference values, demonstrating the methodology's applicability across various chamber models, sources, and MC codes. The corrections ranged from 0.984 to 1.001, with the most significant correction observed for the Varisource VS2000 source, yielding KSG = 0.984, corresponding to a -1.6% correction.

S. Yu. Bazhin, E. N. Shleenkova, V. Yu. Bogatyreva

The article proposes a new approach to assessing the effective doses of flaw detectorists performing flaw detection using portable radionuclide flaw detectors (gamma flaw detectors). The existing approach to assessing effective doses, based on the use of one individual dosimeter placed on work clothes in the chest area, is inadequate for the actual working conditions of exposure of flaw detectorists. Gamma flaw detectors contain a closed man-made source of ionizing radiation in their head, therefore, even in the non-working position, such flaw detectors pose a radiation hazard. When transporting and preparing gamma flaw detectors for work, the flaw detector operator is in close proximity to the radiation source. The irradiation geometry changing during the technological cycle when working with portable gamma flaw detectors at certain stages creates a sharply uneven  irradiation  of  the  flaw  detectorist’s  body.  Therefore,  after  assessing  the  stages  of  the  technological cycle, an option was proposed for a more conservative assessment of effective doses – to change the location of the individual dosimeter on the working clothes of the flaw detectorist, moving the individual dosimeter to the abdominal area. An anonymous study was carried out with the participation of 15 flaw detectorists; three individual dosimeters were displayed on their working clothes: two of them were experimental and were placed in the chest and abdomen; the third (a control dosimeter) was exposed for the quarter on the chest as part of constant individual dosimetric monitoring. In controlled anonymous measurements, the average effective dose, estimated from the readings of dosimeters exposed in the chest area, was equal to 0,95 mSv (median – 0,92 mSv, maximum value – 1,27 mSv). These values were compared with values obtained using dosimeters that were exposed to the abdomen, and the differences were significant (the average effective dose was 1,24 mSv (median – 1,22 mSv, maximum value – 1,78 mSv).

V. Yu. Golikov, S. Yu. Bazhin, E. N. Shleenkova et al.

A model of occupational exposure to gamma flaw detector operators working with portable flaw detectors in the field has been developed. The initial data for the development and verification of the model were the results of measurements of the characteristics of the gamma radiation field at the workplaces of flaw detectors and data from individual dosimetric monitoring. The relationships between the measured (H*(10), Hp(10)) and protection (effective dose) quantities (conversion coefficients) were determined using calculations and phantom experiments simulating three main operations of the full production cycle: transportation of the flaw detector to the place of X-raying of the product, installation of a flaw detector to perform x-raying and X-raying of the product. As a result of the study, it was found that more than 90% of the dose contribution to the readings of an individual dosimeter is due to the installation of the flaw detector in the working position and X-raying of the product. The values of the conversion coefficients for these operations in the form of the ratio of the effective dose values and the readings of dosimeters (Hp(10)) located on the worker's body at chest level (standard place) and abdominal level differ little for both positions of individual dosimeters. The use of maximum conversion coefficient value of 0.8 Sv/Sv corresponding to the operation of X-raying of the product will ensure conservatism in the assessment of the effective dose for the entire production cycle by no more than 15% and 25% for dosimeters located at the chest level and abdominal level, respectively.

Utako Yamamoto, Hirohiko Imai, Kei Sano et al.

The objective of our study is to observe dynamics of multiple substances in vivo with high temporal resolution from multi-spectral magnetic resonance spectroscopic imaging (MRSI) data. The multi-spectral MRSI can effectively separate spectral peaks of multiple substances and is useful to measure spatial distributions of substances. However it is difficult to measure time-varying substance distributions directly by ordinary full sampling because the measurement requires a significantly long time. In this study, we propose a novel method to reconstruct the spatio-temporal distributions of substances from randomly undersampled multi-spectral MRSI data on the basis of compressed sensing (CS) and the partially separable function model with base spectra of substances. In our method, we have employed spatio-temporal sparsity and temporal smoothness of the substance distributions as prior knowledge to perform CS. The effectiveness of our method has been evaluated using phantom data sets of glass tubes filled with glucose or lactate solution in increasing amounts over time and animal data sets of a tumor-bearing mouse to observe the metabolic dynamics involved in the Warburg effect in vivo. The reconstructed results are consistent with the expected behaviors, showing that our method can reconstruct the spatio-temporal distribution of substances with a temporal resolution of four seconds which is extremely short time scale compared with that of full sampling. Since this method utilizes only prior knowledge naturally assumed for the spatio-temporal distributions of substances and is independent of the number of the spectral and spatial dimensions or the acquisition sequence of MRSI, it is expected to contribute to revealing the underlying substance dynamics in MRSI data already acquired or to be acquired in the future.

Or Guttman, Ben Shenhar, Arnab Sarkar et al.

A semi-analytic approximation is derived for the time-dependent fraction $f_γ(t)$ of the energy deposited by radioactive decay $γ$-rays in a homologously expanding plasma of general structure. An analytic approximation is given for spherically symmetric plasma distributions. Applied to Kilonovae (KNe) associated with neutron stars mergers and Type Ia supernovae, our semi-analytic and analytic approximations reproduce, with a few percent and 10% accuracy, respectively, the energy deposition rates, $\dot{Q}_\text{dep}$, obtained in numeric Monte Carlo calculations. The time $t_γ$ beyond which $γ$-ray deposition is inefficient is determined by an effective frequency-independent $γ$-ray opacity $κ_{γ,\text{eff}}$, $t_γ= \sqrt{κ_{γ,\text{eff}}\langleΣ\rangle t^2}$, where $\langleΣ\rangle\propto t^{-2}$ is the average plasma column density. For $β$-decay dominated energy release, $κ_{γ,\text{eff}}$ is typically close to the effective Compton scattering opacity, $κ_{γ,\text{eff}} \approx 0.025~{\rm {cm}^{2}\,g^{-1}}$ with a weak dependence on composition. For KNe, $κ_{γ,\text{eff}}$ depends mainly on the initial electron fraction $Y_e$, $κ_{γ,\text{eff}} \approx 0.03(0.05)~{\rm {cm}^{2}\,g^{-1}}$ for $Y_e \gtrsim (\lesssim) 0.25$ (in contrast with earlier work that found $κ_{γ,\text{eff}}$ larger by 1-2 orders of magnitude for low $Y_e$), and is insensitive to the (large) nuclear physics uncertainties. Determining $t_γ$ from observations will therefore measure the ejecta $\langleΣ\rangle t^2$, providing a stringent test of models. For $\langleΣ\rangle t^2=2\times10^{11}~{\rm g\,{cm}^{-2}\,s^2}$, a typical value expected for KNe, $t_γ\approx1$ d.

Xianwei Wu, Yang Hong, Zhangkai Chen et al.

Bruno Fievet, Claire Voiseux, Catherine Leblanc et al.

Rimon Thomas, Eva Forssell-Aronsson, Martin Hjellström et al.

Abstract There are products available on the online market that are claim to contain unique ‘energies’ that can improve health and wellness by eliminating toxins and pains and energising food and drinking water. We investigated these products by alpha and gamma spectrometry, and the analysis showed that they contained a few to hundreds of kilobecquerels per kilogram of naturally occurring radionuclides from the 232Th and 238U series. The committed effective dose for an adult drinking water that had been in contact with these products just once was estimated to 12 nSv. Considering a worst-case scenario for the workers inhaling the radioactive substance, 1 d of work would result in an effective dose of 0.39 mSv. The product descriptions do not mention the radionuclide content, and concerns are raised for the consumers and workers exposed to these products with no knowledge of the radioactive content.

Hassan Mubashir, Mohamed Mahmoud Mounja, Stefano Salvi et al.

Salvatore Giorgi, Douglas Bellew, Daniel Roy Sadek Habib et al.

Stigma toward people who use substances (PWUS) is a leading barrier to seeking treatment.Further, those in treatment are more likely to drop out if they experience higher levels of stigmatization. While related concepts of hate speech and toxicity, including those targeted toward vulnerable populations, have been the focus of automatic content moderation research, stigma and, in particular, people who use substances have not. This paper explores stigma toward PWUS using a data set of roughly 5,000 public Reddit posts. We performed a crowd-sourced annotation task where workers are asked to annotate each post for the presence of stigma toward PWUS and answer a series of questions related to their experiences with substance use. Results show that workers who use substances or know someone with a substance use disorder are more likely to rate a post as stigmatizing. Building on this, we use a supervised machine learning framework that centers workers with lived substance use experience to label each Reddit post as stigmatizing. Modeling person-level demographics in addition to comment-level language results in a classification accuracy (as measured by AUC) of 0.69 -- a 17% increase over modeling language alone. Finally, we explore the linguist cues which distinguish stigmatizing content: PWUS substances and those who don't agree that language around othering ("people", "they") and terms like "addict" are stigmatizing, while PWUS (as opposed to those who do not) find discussions around specific substances more stigmatizing. Our findings offer insights into the nature of perceived stigma in substance use. Additionally, these results further establish the subjective nature of such machine learning tasks, highlighting the need for understanding their social contexts.

Eric David-Bosne, Ângelo Costa, Benedikt Bergmann et al.

Electron Emission Channeling (EC) is a powerful technique for the investigation of the lattice location of radioactive isotopes implanted into single crystals. After implantation the isotopes occupy certain lattice locations in the crystal, which can in some cases be altered by annealing. Upon decay, the emission of a charged particle, typically a beta, may result in a channeling trajectory when its starting lattice location is aligned with major symmetry axes or planes of the crystal. By measuring the emission anisotropy in the direction of these axes for distinct annealing temperatures, the lattice location of the isotope can be determined with great precision and insightful information can be obtained on how annealing affects the occupied sites. This work reports on the installation of a Timepix3 quad detector and Katherine Gen2 readout in an experimental setup located at ISOLDE at CERN. The large increase in the number of pixels of the Timepix3, in comparison to previously used pad detectors, required more sophisticated tools for data treatment and fitting of channeling patterns. From this need, the PyFDD software was born. Its latest update features an intuitive graphical interface, with tools for noise masking, pattern visualization, simulations browsing, chi-square or maximum likelihood based fits and gamma background correction.

Gyoung G. Jang, Alexander I. Wiechert, Yong-Ha Kim et al.