Hasil untuk "Radioactivity and radioactive substances"

Mengman Wei, Qian Peng

Early initiation of alcohol, nicotine, cannabis, and other substances predicts later substance use disorders and related psychopathology. We integrate time-varying environmental factors with polygenic risk scores (PRS) in a longitudinal framework to identify determinants of substance initiation in adolescence. Using data from the Adolescent Brain Cognitive Development (ABCD) Study with repeated assessments over approximately four years, we defined time-to-event outcomes for first use of alcohol, nicotine, cannabis, and any substance. We constructed high-dimensional panels of time-varying environmental covariates across family, school, neighborhood, behavioral, and health domains, alongside time-invariant covariates and PRS for alcohol, cannabis, nicotine, and general substance use disorders. Time-varying Cox models with clustered standard errors were applied. Univariate analyses showed broad associations between earlier initiation and multiple environmental domains, including impulsivity, sleep disturbance, parental monitoring, caffeine use, and school functioning. In multivariable models, a smaller set of predictors remained robust, particularly impulsivity traits, parental monitoring, and selected health and lifestyle factors. PRS were positively associated with earlier initiation, with the strongest and most consistent effects for nicotine-related genetic risk. Secondary analyses using marginal structural models suggested that higher parental monitoring is protective, whereas higher impulsivity and caffeine exposure are associated with increased risk. These results demonstrate that integrating dynamic environmental exposures with genetic liability can identify key risk factors for adolescent substance initiation and highlight actionable targets for prevention.

V. R. Batalov, M. V. Ishunina, A. V. Efimov et al.

Currently, the most common methods to measure the activity of transuranium elements in biological samples are alpha radiometry and alpha spectrometry. Of these, alpha spectrometry is the most sensitive and selective method. However, this method is not sufficiently sensitive to control hardly soluble compounds of plutonium in the human body. For example, upon an intake of hardly soluble compounds of plutonium at the level of annual limit of intake, a year later, Pu in a daily urine sample is expected to be 0.4 mBq. Since the lower limit of measurement of alpha spectrometry is about 0.5 mBq, during the first 2 years as minimum, the workers who have contact with hardly soluble compounds of plutonium are not provided with a reliable monitoring of intakes. To solve this problem, a new technique of analysis was developed based on the plutonium activity measurement using the method of inductively coupled plasma mass spectrometry. This technique allows measuring plutonium by mass spectrometer in daily urine samples and blood samples after separation from interfering isotopes by anionic exchange chromatography. The method takes much less measurement time and is much more sensitive to long-lived isotopes. It enables reducing the lower limit of measurement by a factor of five compared to the alpha spectrometry method. Also, the technique for the first time allows to measure separately the activity of plutonium-239 isotopes and plutonium-240 isotopes, the energies of which are indistinguishable on alpha spectra. The plutonium activity was measured by the two methods in parallel in 88 daily urine samples collected from the personnel of the federal state unitary enterprise “Mayak Production Association” working primarily with hardly soluble compounds of plutonium. The analysis of the measurements of these samples demonstrated no statistically significant differences between the results obtained. Also, these results testify to better applicability of mass spectrometry for the activities below the lower limit of measurement of alpha spectrometry. The developed method of analysis can be applied to estimate the levels of current intake of hardly soluble compounds of plutonium, for retrospective dosimetry and as an express method to obtain the intake estimates by the plutonium activity in blood in non-routine situations.

Eduardo Tadeu Stehling Saraiva, Vanderley Vasconcelos, Daniel Almeida Magalhães Campolina et al.

The “Centro de Desenvolvimento da Tecnologia Nuclear” (CDTN) is developing the prototype of a computer-controlled mechanism for moving a nuclear fuel irradiation capsule, called “Dispositivo de Movimentação da Cápsula” (DMC). This mechanism will be installed in the “Reator Multipropósito Brasileiro” (RMB), which is a Brazilian research reactor currently under construction, and will be used to carry out fuel qualification tests, such as power ramp tests. In addition to the engineering design of the mechanical system, CDTN is also developing the engineering design of the DMC electric-electronic system including a control and data acquisition software. In the context of nuclear facilities, human factors play an important role in safety and reliability assessments. Many techniques are suitable for modeling and analyzing human reliability and, among these, can be highlighted “Standardized Plant Analysis Risk‑Human Reliability Analysis (SPAR‑H)”. In this work, the applicability of this technique to predict human error probabilities (HEPs) is illustrated as an example of a quantitative study to improve the safety and reliability of the DMC electric-electronic system through acting on human factors issues.

T. A. Kormanovskaya

The paper presents results of analysis of data accumulated during 2022–2024 in the Federal databank of radiation doses to the public from exposure to natural and technologically enhanced background radiation, which functions within the framework of the Unified State System for Monitoring and Accounting for Individual Doses of Radiation to the Citizens. The results of 598,604 measurements of ambient gamma dose rate in dwellings and public buildings and outdoors in various regions of the country, 155,249 measurements of indoor radon isotopes equilibrium equivalent concentration, 58,804 measurements of activity concentrations of natural radionuclides in drinking water were analyzed. Based on these data, a hygienic assessment of the radiation safety of the population of the Russian Federation due to exposure to natural sources of ionizing radiation in the period 2021–2023 was performed. The analysis of data on indoor radon isotopes equilibrium equivalent concentration showed that in a number of regions of Russia (the Altai Republic, the Republic of Sakha (Yakutia), the Republic of Tyva, Zabaykalsky Krai, Irkutsk Oblast, etc.), in the study period, hygienic norms (action levels) for dwellings and public buildings were exceeded. The analysis of data on activity concentrations of natural radionuclides in drinking water revealed significant (more than an order of magnitude) exceedances of the intervention level for radon in drinking water of certain sources of drinking water supply in Chelyabinsk Oblast and Zabaikalsky Krai. The assessment of public doses due to natural sources of ionizing radiation showed that in several regions of Russia (the Altai Republic, the Republic of Bashkortostan, the Republic of Tyva, Irkutsk Oblast, Stavropol Krai, etc.) public exposure to natural sources can be classified as “increased” (average annual effective dose is in the range 5–10 mSv), and in Zabaikalsky Krai public exposure can be classified as “high” (average annual effective dose exceeds 10 mSv/year) in 2021 and 2023.

Layla Bouzoubaa, Muqi Guo, Joseph Trybala et al.

TikTok has emerged as a major source of information and social interaction for youth, raising urgent questions about how substance use discourse manifests and circulates on the platform. This paper presents the first comprehensive analysis of publicly visible, algorithmically surfaced substance-related content on TikTok, drawing on hashtags spanning all major substance categories. Using a mixed-methods approach that combines social network analysis with qualitative content coding, we examined 2,333 substance-related hashtags, identifying 16 distinct hashtag communities and characterizing their structural and thematic relationships. Our network analysis reveals a highly interconnected small-world structure in which recovery-focused hashtags such as \textit{\#addiction}, \textit{\#recovery}, and \textit{\#sober} serve as central bridges between communities. Qualitative analysis of 351 representative videos shows that Recovery Advocacy content (33.9\%) and Satirical content (28.2\%) dominate, while direct substance depiction appears in only 26\% of videos, with active use shown in just 6.5\% of them. These findings suggest that the algorithmically surfaced layer of substance-related discourse on TikTok is predominantly oriented toward recovery, support, and coping rather than explicit promotion of substance use. We further show that hashtag communities and video content are closely aligned, indicating that substance-related discourse on TikTok is shaped through organic community formation within platform affordances rather than widespread adversarial evasion of moderation. This work contributes to social computing research by showing how algorithmic visibility on TikTok shapes the organization of substance-related discourse and the formation of recovery and support communities.

Y. Tojo, Mikako Ishii, Kazuki Tamura et al.

After the Fukushima Daiichi nuclear accident, municipal solid waste (MSW) contaminated with radiocesium was generated. In Japan, approximately 80% of MSW by weight has been incinerated. As consequence, radiocesium was retained in incineration residue after the accident. Among the incineration residues, fly ash with high radioactivity was transported to an interim storage facility and special treatment has been carried out. While, bottom ash with radioactivity levels of <8000 Bq kg-1 wet has been directly deposited in conventional MSW landfills. The radiocesium leaching from bottom ash is low, but the reason for this low leaching remains unclear. In this study, leaching tests and microscopic observations of bottom ash containing stable Cs were conducted to investigate the mechanism making Cs leaching low. It is noted that the ash used was simulated ash created from combusting refuse derived fuel (RDF) to which stable Cs was added, not real radioactive ash. Based on pH dependence testing, the Cs leaching increased as the pH decreased. The amount of Cs leached in the neutral range was 2-4% mass of the total content. Electron probe microanalysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy confirmed that certain particles in bottom ash contain concentrated Cs. These particles were found to comprise aluminum, silicon, potassium, and oxygen at their core, surrounded by concentrated Cs. Raman microscopy suggested that these particles are microcline. Co-heating of microcline with Cs carbonate led to the condensation of Cs in a manner similar to particles observed in bottom ash, and Cs was captured in a glassy substance formed on the microcline surface, which reduced the leaching of Cs.

Akira Takenaka, J. Hui, Rui Li et al.

We customized a laser calibration system and four radioactive γ-ray calibration sources for the Jiangmen Underground Neutrino Observatory (JUNO), a 20-kton liquid scintillator-based neutrino detector. The laser source system was updated to realize the isotropic light emission timing within ±0.25 nsec level and to allow the tuning of the laser intensity covering more than four orders of magnitude. In addition, methods to prepare four different radioactive sources (18F, 40K, 226Ra, and 241Am), covering energies from 0 (10) keV to 0 (1) MeV, for the JUNO detector were established in this study. The radioactivity of each source and the risk of radioactive substance leaking into the detector from the source were confirmed to meet the experimental requirements.

Amena Ali Hussain, Eva Forssell-Aronsson, Tobias Rosholm et al.

Introduction: PET/CT and PET/MRI are valuable multimodality imaging techniques for visualizing both functional and anatomical information. The most used PET reconstruction algorithm is Ordered Subset Expectation Maximization (OSEM). In OSEM, the image noise increases with increased number of iterations, and the reconstruction needs to be stopped before complete convergence. The Bayesian penalized likelihood (BPL) algorithm, recently introduced, uses a noise penalty factor (β) to achieve full convergence while controlling noise. This study aims to evaluate how reconstruction algorithms and lesion radioactivity levels affect PET image quality and quantitative accuracy across three different PET systems. Materials and Methods: A NEMA phantom was filled with 18F and scanned by one PET/MRI and two PET/CT systems with sphere-to-background concentration ratio (SBR) of 2:1, 4:1, or 10:1. PET images were reconstructed with OSEM or BPL with TOF. The number of iterations and β-values were varied, while the matrix size, number of subsets, and filter size remained constant. Contrast recovery (CR) and background variability (BV) were measured in images. Results: CR increased with increased sphere size and SBR. CR and BV decreased with increased β for the 10mm sphere. Increased number of iterations in OSEM showed increased BV with limited variation in CR. BPL gave higher CR and lower BV values than OSEM. The optimal reconstruction was BPL with β between 150 and 350, where BPL was available, and OSEM with two iterations and 21 subsets for the PET/CT without BPL. Conclusion: BPL outperforms OSEM, and SBR significantly influences tracer uptake quantification in small lesions. Future studies should explore the clinical implications of these findings on diagnosis, staging, prognosis, and treatment follow-up.

Yu. V. Druzhinina, Z. A. Lantukh, K. V. Tolkachev et al.

Diagnostic reference levels are one of the effective tools for optimizing patient radiation doses in diagnostic radiology. The staff of domestic radiology departments does not have an understanding of the development process and use of diagnostic reference levels during X-ray examinations, although this tool is a generally accepted in practice abroad. The article shows the experience of forming regional diagnostic reference levels based on measurements provided by the accredited testing laboratory of the Scientific and Practical Clinical Center for Diagnostics and Telemedicine Technologies of the Moscow Healthcare Department. The diagnostic reference levels for radiography in Moscow were developed for eight of the most common types of examinations based on the operation of 216 digital X-ray machines. The resulting levels, expressed in the dose-area product (cGy-cm2) and effective dose (mSv), were compared with the local diagnostic reference levels for the Ryazan region, Russia, and national diagnostic reference levels for other countries. The analysis showed continuity in the values. Some types of studies have been optimized. The developed diagnostic reference levels are the quality performance indicators foe diagnostic radiology departments and will be used to optimize a patient radiation dose during diagnostic studies in Moscow.

Yao Ge, Sudeshna Das, Karen O'Connor et al.

Substance use disorders (SUDs) are a growing concern globally, necessitating enhanced understanding of the problem and its trends through data-driven research. Social media are unique and important sources of information about SUDs, particularly since the data in such sources are often generated by people with lived experiences. In this paper, we introduce Reddit-Impacts, a challenging Named Entity Recognition (NER) dataset curated from subreddits dedicated to discussions on prescription and illicit opioids, as well as medications for opioid use disorder. The dataset specifically concentrates on the lesser-studied, yet critically important, aspects of substance use--its clinical and social impacts. We collected data from chosen subreddits using the publicly available Application Programming Interface for Reddit. We manually annotated text spans representing clinical and social impacts reported by people who also reported personal nonmedical use of substances including but not limited to opioids, stimulants and benzodiazepines. Our objective is to create a resource that can enable the development of systems that can automatically detect clinical and social impacts of substance use from text-based social media data. The successful development of such systems may enable us to better understand how nonmedical use of substances affects individual health and societal dynamics, aiding the development of effective public health strategies. In addition to creating the annotated data set, we applied several machine learning models to establish baseline performances. Specifically, we experimented with transformer models like BERT, and RoBERTa, one few-shot learning model DANN by leveraging the full training dataset, and GPT-3.5 by using one-shot learning, for automatic NER of clinical and social impacts. The dataset has been made available through the 2024 SMM4H shared tasks.

Yuki Sato, Y. Terasaka

ABSTRACT The Fukushima Daiichi Nuclear Power Station (FDNPS) suffered a meltdown in the aftermath of the large tsunami caused by the Great East Japan Earthquake that occurred on 11 March 2011. A massive amount of radioactive substance was spread over a wide area both inside and outside the FDNPS site. In this study, we present an approach for visualizing a radioactive hotspot on a standby gas-treatment system filter train, a highly contaminated piece of equipment in the air-conditioning room of the Unit 2 reactor building of FDNPS, using radiation imaging based on a Compton camera. In addition to fixed-point measurements using only the Compton camera, data acquisition while moving using an integrated Radiation Imaging System (iRIS), which combines a Compton camera with a simultaneous localization and mapping device and a survey meter, enabled the three-dimensional visualization of the hotspot location on the filter train. In addition, we visualized the hotspot and quantitatively evaluated its radioactivity. Notably, the visualized hotspot location and estimated radioactivity value are consistent with the accident investigation report of the FDNPS. Finally, the extent to which the radioactivity increased the ambient dose equivalent rate in the surrounding environment was explored. Graphical abstract

Xin-yu Ge, Yuandong Zheng, Yifei He et al.

BACKGROUND Catalpol, one of the main bioactive components isolated from Rehmannia glutinosa, was developed by Suzhou Youseen for the treatment of ischemic stroke; however, preclinical information about its absorption, distribution, metabolism, and excretion (ADME) in animals is inadequate. OBJECTIVE This study aimed to illuminate the pharmacokinetics (PK), mass balance (MB), tissue distribution (TD), and metabolism of catalpol after a single intragastric administration of 30 mg/kg (300 μCi/kg) [3H]catalpol in rats. METHODS Radioactivity in plasma, urine, feces, bile, and tissues was measured by liquid scintillation counting (LSC), and metabolite profiling was characterized by UHPLC-β-ram and UHPLC-Q- Extractive plus MS. RESULTS The radio pharmacokinetic results showed that catalpol was rapidly absorbed by Sprague‒Dawley (SD) rats, with a median Tmax of 0.75 h and an arithmetic mean half-life (t1/2) of the total radioactivity of approximately 1.52 h in plasma. The mean recovery of the total radioactive dose was 94.82%±1.96% over 168 h postdose (57.52%±12.50% in the urine and 37.30%±12.88% in the feces). The parent drug catalpol was the predominant drug-related substance in rat plasma and urine, while M1 and M2, two unidentified metabolites, were detected in feces. When [3H]catalpol was incubated with β-glucosidase and rat intestinal flora, we found that the same metabolites M1 and M2 were produced in both incubation systems. CONCLUSIONS Catalpol was excreted mainly through the urine. The drug-related substances were primarily concentrated in the stomach, large intestine, bladder, and kidney. Only the parent drug was detected in the plasma and urine, and M1 and M2 were detected in the feces. We speculate that the metabolism of catalpol in rats was mainly mediated by the intestinal flora, resulting in an aglycone-containing hemiacetal hydroxyl structure.

K.C.W. Consatti, W. S. Santos, J. V. B. Valença et al.

In radiology, knowing the X-ray spectrum characteristics makes it possible to estimate the absorbed dose in the patient and to improve image quality. In this study, an X-ray generator was proposed using the MCNPX code and to validate it, the simulated spectrum was compared to the data provided from AAPM Task Group 195, which resulted in a percentage difference of 8.7%. Furthermore, several X-ray spectra were generated and compared to the spectra obtained from commercially available softwares as xpecgen and SpekCalc. The percentage differences were of the order of 13% in comparison with SpekCalc and 8% with xpecgen. The major differences obtained between those spectra were concentrated in the region of characteristic peaks, independently if variations in electron beam energy, target angle or filtration thickness were performed.

Layla Bouzoubaa, Ramtin Ehsani, Preetha Chatterjee et al.

The media's representation of illicit substance use can lead to harmful stereotypes and stigmatization for individuals struggling with addiction, ultimately influencing public perception, policy, and public health outcomes. To explore how the discourse and coverage of illicit drug use changed over time, this study analyzes 157,476 articles published in the Philadelphia Inquirer over a decade. Specifically, the study focuses on articles that mentioned at least one commonly abused substance, resulting in a sample of 3,903 articles. Our analysis shows that cannabis and narcotics are the most frequently discussed classes of drugs. Hallucinogenic drugs are portrayed more positively than other categories, whereas narcotics are portrayed the most negatively. Our research aims to highlight the need for accurate and inclusive portrayals of substance use and addiction in the media.

T. B. Baltrukova, S. V. Voronkova, A. V. Vodovatov

As a part of administrative reform and “regulatory guillotine” in Russia in 2020-2021, several significant changes in the governmental regulation of dental care have occurred: implementation of new version of Order of provision of dental care and infrastructure of governmental dental facilities; approval of Rules of carrying of X-ray examinations; development of changes in the sanitary-epidemiological requirements to medical facilities. Meanwhile, the requirements on the radiation safety in the medical facilities remained the same. The lack of coordination during the development of new documents between the Ministry of Healthcare and Rospotrebnadzor resulted in preservation of the existing problems with the use of X-ray equipment in dentistry (for example, related to the allocation of dental X-ray units in residual and public buildings) and appearance of new problems (for example, removal of a requirement for the license in radiology for dentists). The study is focused on the analysis of the issues of regulation of the provision of radiation safety for dental care of public of the Russian Federation. It includes a review of the acting regulatory documents of the Ministry of Healthcare and Rospotrebnadzor, regulating the allocation of dental X-ray units and provision of dental X-ray examinations, with subsequent identification of the major issues and problems. The results of the study indicate that changes in the regulatory documents of the Ministry of Healthcare implemented in 2020-2021 contradict the acting requirements on radiation safety. It is necessary to further improve the legislative base regulating the dental care: harmonization of the acting requirements on the equipment of the dental rooms, orders and standards of dental care, training of staff. The harmonized base should result in a provision of qualitative dental care and radiation safety.

Douglas Rodriguez Brasil, Andressa dos Santos Nicolau, Roberto Schirru et al.

This paper aims to estimate the rate of particulate contaminants emitted by multiple sources, whose values are unknown, using the values identified by the receptors distributed around the sources. In a nuclear emergency with release of radionuclides into the atmosphere, in order to make the correct decision, it is necessary to identify the source term and its release rate, as well as the meteorological data, essential factors for defining the direction and size of the radioactive plume. For this purpose, a model of Particle Swarm Optimization (PSO) is applied together with a mathematical model of Gaussian dispersion, being created the program Particle Swarm Optimization Dispersion Model (PSODM).

Elsayed K. Elmaghraby, Mohamed Bahaaeldin-Afifi

The pattern of radiation energy deposition in substances at the microscopic level of lattice, molecule size, or the cell's nucleus is not uniform. The energy of radiation is transferred to the substance medium in the form of discrete, time-dependent, spatially correlated events with excitations/ionizations are the processes involved. The response of material on the macroscopic level to radiation effects depends on the microscopic pattern of energy deposition. A mathematical model that combines the specific number of sites available for the interaction of radiation and the detected signals of the property was proposed and discussed. This model emphasizes the phenomenon of log-dose response for a moderate amounts of nuclear radiation affects the material, especially detector materials. A parameter ($α_{ν}^{\bullet }$) was adopted to represent the remaining fraction of sites that were affected in the material by one unit dose at which the damage/change/modification of its properties occurs. The recovery factor of the effect and the delayed retardation enhancement factor are included in the model.

J. Qiao, Haitao Zhang, P. Steier et al.

We present an application of multi-isotopic fingerprints (i.e., 236U/238U, 233U/236U, 236U/129I and 129I/127I) for the discovery of previously unrecognized sources of anthropogenic radioactivity. Our data indicate a source of reactor 236U in the Baltic Sea in addition to inputs from the two European reprocessing plants and global fallout. This additional reactor 236U may come from unreported discharges from Swedish nuclear research facilities as supported by high 236U levels in sediment nearby Studsvik, or from accidental leakages of spent nuclear fuel disposed on the Baltic seafloor, either reported or unreported. Such leakages would indicate problems with the radiological safety of seafloor disposal, and may be accompanied by releases of other radionuclides. The results demonstrate the high sensitivity of multi-isotopic tracer systems, especially the 233U/236U signature, to distinguish environmental emissions of unrevealed radioactive releases for nuclear safeguards, emergency preparedness and environmental tracer studies. Anthropogenic activities lead to the accumulation of radioactive substances in the environment. Here the authors use multi-isotopic fingerprints of uranium and iodine to discover a previously unknown source of reactor uranium in the Baltic Sea, likely sourced from a Swedish nuclear facility.

V. Yu. Golikov, L. A. Chipiga, A. V. Vodovatov et al.

The paper presents the data that allow calculate the attenuation factors in lead, tungsten and concrete of various thicknesses or the thickness of shielding made of these materials for a given attenuation factor for the spectra of gamma radiation of 131I and 177Lu radionuclides. Using these data the effectiveness of the protection of supporting equipment (portable containers, shielded syringes, etc.) and the possible doses of external radiation of medical personnel in the radionuclide therapy department were calculated. It is shown that there are short-term operations in the production process when a radiation source (container with a capsule with activity, syringe with activity), being near the body of a medical worker, creates a significant dose rate. For this reason the annual individual dose of external exposure of a medical worker can approach or exceed 1/3 of the dose limit. Calculation of the attenuation of 131I gamma radiation by stationary shield showed that the thickness of walls and floors made of concrete 200 – 400 mm will ensure that the permissible values of the dose rates of gamma radiation in the air do not exceed at annual turnover of activity in the radionuclide therapy department of ~ 3.3 · 1012 Bq.

Bruna Cortez

Dating of sediments was used by physics method in this work, in the physics methods the radioactivity is present, but usually it is method based on the storage of energy of radiation in the solid, in which will be employed. In the present work, Icapara sediment dating was used Electron Paramagnetic Resonance (EPR) method, in this technique the energy absorption occurs when the frequency of the incident wave is in resonance with the energy difference made by the magnetic field between the parallel and antiparallel directions to this field with the irradiated sample that creates defects in its structure.  In the state of S˜ao Paulo, in the region of Iguape on the southeast coast, it is a place called Icapara, a large sand terrace that was formed due to sea level fluctation that ocorred more than 130 thousand years ago. A sample was taken from a point about 9 meters above the current control of the sea. An age of about 38,000 ±12,000 and 46,000 ± 7,000 years were obtained (EPR) to correlate with the Quaternary period and will be presented to the data obtained.