Radioactive Decay Research Articles

Identification and characterization of phytochemicals in methanolic extract of roots of Datura fastuosa using various techniques

BackgroundPlant extracts have attracted significant interest among researchers due to their potential bioactivity and crucial contribution to the production of pharmaceutical compounds. In this study, the primary objective was to extract, analyze and characterize the bioactive compounds found in the methanol root extract of Datura fastuosa (D. fastuosa). This was achieved using various analytical techniques such as gas chromatography/mass spectrometry (GC–MS), ultra-violet visible spectrophotometry, Fourier-transform infrared (FT-IR), nuclear magnetic radiation spectrometry (NMR) and DPPH free radical scavenging activity assay.ResultsGC–MS analysis of the methanol root crude extract identified 49 compounds. Three compounds were isolated via column chromatography; one was pure, with a sharp melting point and clean IR spectrum, while the other two showed broad melting points and IR interferences. Comprehensive investigation of the pure extract revealed a UV profile with two distinct bands (300–800 nm) and confirmed functional groups (alcohol, alkanes, alkenes, carbonyl, methylene, and methyl) through FT-IR analysis. The 1HNMR (proton nuclear magnetic resonance spectroscopy) signal confirmed the presence of forty-nine non-equivalent protons, 13CNMR (Carbon-13 nuclear magnetic resonance spectroscopy) signal confirmed the presence of 32 non-equivalent carbons and DEPT-135 (distortionless enhancement by polarization transfer-135) signal confirmed the presence of 24 carbons (17 for odd and 7 for even) which are protons containing carbons in the compound. Combining the above mentioned analyses with data obtained from the GC/MS analysis of National Institute of Standards and Technology (NIST) library, the isolated pure compound exhibited a structural similarity to 1-(7-(3-hydroxyphenyl)-1,1,4a,5,6,9,10a,10b-octamethyl-1,2,3,4,4a,4b,6a,7,8,9,10,10a,10b,11,12,12a-hexadecahydrochrysen-2-yl)propan-1-one, with a chemical formula of C35H50O2.ConclusionsThe presence of various notable compounds, including phenolics, flavonoids, alkaloids, steroids etc., within the methanol root extract of D. fastuosa signifies its pharmacological potential. The methanol crude extract demonstrated antioxidant potential compared to standard ascorbic acid, exhibiting DPPH scavenging activity. Previous research has demonstrated the bioactivity of some of these compounds, further elucidating the plant’s medicinal properties. These findings not only suggest opportunities for developing synthetic drugs but also underscore its direct therapeutic potential in addressing diverse ailments.

Assessment of shielding efficiency of highly energetic electromagnetic radiation for lead-free cuprate-class material: Effect of MnFe2O4 ratios

In this work, efficient lead-free cuprate-based shielding materials mixed with different ratios (x = 0.1–2 wt%) of magnetic MnFe2O4 powder against nuclear radiation were proposed. The samples were prepared by using a mixture of raw materials of oxides for the preparation of the host cuprate Y1Ba2Cu3Oy materials and a mixture of nitrates in the presence of solvent for the formation of magnetic MnFe2O4 powder additive. The phase, crystalline structure, and composition were examined by X-ray diffraction. The main Y1Ba2Cu3Oy phase revealed good crystallinity and orthorhombic structure. As the ratio of magnetic MnFe2O4 powder additive increases, the orthorhombicity decreases. Gamma shielding performance was analyzed by using MNCP5 code. The analyses indicate that the addition of magnetic powder has an influence on the shielding performance of cuprate-class material. The radiation shielding performance of prepared materials is nearly the same with the low ratios of MnFe2O4 (i.e. x = 0.1 and 0.5 wt%). Yet, with further increasing the amount of MnFe2O4 beyond x = 0.5 wt%, a considerable detraction of shielding parameters was noticed, as estimated by the Monte Carlo simulation (MCNP-5 code). The linear attenuation coefficient of cuprate-class materials decreased by 19.6 %, 33.6 %, 19.3 %, and 19.7 %, respectively at 0.015 MeV, 0.1 MeV, 0.662 MeV, and 15 MeV when the MnFe2O4 concentration increased between 0.1 and 2 wt%.

Research on the degradation of resolution in cameras based on CMOS image sensor under γ- and X-rays irradiation

Remote control engineering in industry usually requires cameras to assist target identification and detection, but the cameras working in nuclear environments face the threat of radiation-induced degradation. Both γ- and X-rays in nuclear environments will cause ionizing radiation damage, but the difference in degradation of camera’s performance induced by ionizing radiation damage with equivalent total ionizing dose (TID) of these two rays is unclear, which is crucial for the evaluation of camera performance in a nuclear radiation environment. In order to figure out the degradation of CMOS cameras by ionization radiation damage under different rays, this study conducted irradiation experiments on CMOS image sensors under X-ray with 10 keV and 60Co-γ ray with 1.25 MeV, respectively, and then tested and calculated the resolution of camera based on this CMOS image sensor. After comparing and analyzing the results, it was found that the dark current and full well capacity of the CIS, as well as the resolution of the camera, were more severely degraded after X-ray irradiation. Further analysis found that the interface dose enhancement effect of X-ray, as well as the generation of high-density oxide trapped charges in the gate oxide, aggravated the degradation of full well capacity on the CIS after X-ray irradiation, resulting in more severe degradation in the resolution of the CMOS camera. This study provides theoretical basis for the safety and reliability evaluation of cameras in strong nuclear radiation environments.

Accessing the Characteristics of Nuclear Reactions: A Radioactive Decay and Half-Life Measurement Study

This study investigates the impact of external environmental factors, specifically electromagnetic fields and pressure variations, on the decay constants and half-lives of three radioactive isotopes: 60Co, 137Cs, and 226Ra. By conducting controlled laboratory experiments, the research aimed to quantify the extent to which these factors influence decay rates, challenging the traditional assumption of invariant half-lives. The isotopes were exposed to varying levels of electromagnetic fields (0-100 Gauss) and pressure (1-10 atm), with decay rates measured using high-resolution gamma-ray spectrometers. The results revealed that while 137Cs exhibited the most significant sensitivity, with a 13.04% increase in decay constant under extreme conditions, 60Co and 226Ra showed moderate and minimal changes, respectively. These findings have important implications for fields such as nuclear medicine, radiometric dating, and nuclear waste management, where precise knowledge of decay rates is crucial. The study contributes to a deeper understanding of nuclear decay processes and highlights the need for further research on the effects of other environmental factors, such as temperature and chemical composition, on radioactive decay.

Lead-212/Bismuth-212 InVivo Generator Based on Ultrasmall Silver Telluride Nanoparticles.

Radionuclide therapy employing alpha emitters holds great potential for personalized cancer treatment. However, certain challenges remain when designing alpha radiopharmaceuticals, including the lack of stability of used radioconjugates due to nuclear decay events. In this work, ultrasmall silver telluride nanoparticles with a core diameter of 2.1 nm were prepared and radiolabeled with lead-212 using a chelator-free method with a radiolabeling efficiency of 75%. The results from the invitro radiochemical stability assay indicated a very high retention of bismuth-212 despite the internal conversion effects originating from the decay of 212Pb. To further evaluate the potential of the nanoparticles, they were radiolabeled with indium-111, and their cell uptake and subcellular distribution were determined in 2D U87 cells, showing accumulation in the nucleus. Although not intentional, it was observed that the indium-111-radiolabeled nanoparticles induced efficient tumor cell killing, which was attributed to the Auger electrons emitted by indium-111. Combining the results obtained in this work with other favorable properties such as fast renal clearance and the possibility to attach targeting vectors on the surface of the nanoparticles, all well-known from the literature, these ultra-small silver telluride nanoparticles provide exciting opportunities for the design of theragnostic radiopharmaceuticals.

Evaluation of experimental and simulated gamma ray shielding ability of ZnCo2O4 and ZnCo2O4/graphene nanoparticles

Pristine zinc cobaltite (ZnCo2O4) and graphene zinc cobaltite nanoparticles (NPs) have been successfully synthesized by hydrothermal method. The physical properties of both structures were studied using field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). XRD results indicated a formation of spinel structure. The elemental composition of the samples has been determined through EDX analysis. From morphological investigation, the aggregation of grains and nano-sized quasi-spherical grains was observed. Nuclear radiation protection investigation for gamma-ray has been studied for both samples. The protection factors against gamma rays, including linear attenuation coefficients (LAC), mass attenuation coefficients (MAC), transmission Factor (TF), radiation protection efficiency (RPE) mean free path (MFP), half value layer (HVL) and tenth value layer (TVL) were calculated. In addition to the experimental examination, simulation with GEANT4 simulation code was also used for both samples to examine the shielding parameters. The most essential parameters of gamma shielding factors such as mass attenuation coefficients (MAC), mean free path (MFP), half value layer (HVL), tenth value layer (TVL) and linear attenuation coefficients (LAC) were evaluated both practically and by simulation. Practically, these values were: 0.75/0.78 cm2/g, 0.22/0.20 cm, 0.15/0.14 cm, 0.50/0.47 cm, and 4.55/4.86 cm−1, for ZnCo2O4 and ZnCo2O4/graphene samples, respectively. By simulation, these values were: 0.65/0.70 cm2/g, 0.25/0.22 cm, 0.17/0.16 cm, 0.59/0.52 cm, and 3.91/4.38 cm−1, for ZnCo2O4 and ZnCo2O4/graphene samples, respectively. The results show that the presence of graphene has affected all the protection parameters. Keywords: Zinc cobaltite, structural properties, gamma shielding, hydrothermal method.

Recommended Nuclear Structure and Decay Data for A=202 Isobars

Evaluated nuclear structure and decay data for all nuclei with mass number A=202 (202Os, 202Ir, 202Pt, 202Au, 202Hg, 202Tl, 202Pb, 202Bi, 202Po, 202At, 202Rn, 202Fr and 202Ra), are presented. All available experimental data are compiled and evaluated, and best values for level and γ-ray energies, quantum numbers, lifetimes, γ-ray intensities and transition probabilities, as well as other nuclear properties, are recommended. Inconsistencies and discrepancies that exist in the literature are discussed. A number of computer codes (https://www-nds.iaea.org/public/ensdf_pgm/) developed by members of the NSDD network were used during the evaluation process. This work supersedes the earlier evaluation by F.G. Kondev (2007Ko42), published in Nuclear Data Sheets108, 1471 (2007).

Temporal Variations of 222Rn Density Distributions in the Lunar Exosphere

Because of radiogenic processes, the lunar interior is a source of rare gases like helium (4He), argon (40Ar), and radon (222Rn) that might be released continuously, or impulsively during moonquakes. The detection of radon is therefore important in the sense that it can help trace the crustal dynamics on the Moon. In this study, we will introduce a Monte Carlo–based model designed to investigate the time-dependent transient dynamics of the lunar 222Rn exosphere. Our model accounts for the background emission and transient ejection of gas molecules from the lunar surface, encompassing loss processes such as radioactive decay, photoionization, and the cold trapping in permanently shadowed regions near the poles. Additionally, it incorporates the diurnal temperature fluctuations of the lunar surface, which significantly influence the condensation duration of the radon atoms and their subsequent release near the sunrise. This model also can support future observations in missions such as Chang’E 6 or other lunar explorations.

Neutron and fission decay width of superheavy compound nuclei

We have systematically studied the level density parameter, nuclear level density and decay width of neutron and fission of superheavy nuclei. This paper is validated by comparing with available experiments for [Formula: see text]U and [Formula: see text]Pu. The angular dependence of level density parameter, level densities and ratio of [Formula: see text] and [Formula: see text] the thermal excitation energy (U) have been studied in the superheavy region [Formula: see text]. The role of entrance channel parameter on decay width of neutron and fission has been studied both in cold and hot fusion reactions in the superheavy region [Formula: see text]. Systematic variation of [Formula: see text] and [Formula: see text] is observed in both the cases. Finally, predicted [Formula: see text] for the synthesis of superheavy nuclei [Formula: see text] and 120.

Radioactive Gamma-Ray Lines from Long-lived Neutron Star Merger Remnants

The observation of a kilonova AT2017gfo associated with the gravitational wave event GW170817 provides the first strong evidence that neutron star mergers are dominant contributors to the production of heavy r-process elements. Radioactive gamma-ray lines emitted from neutron star merger remnants provide a unique probe for investigating the nuclide composition and tracking its evolution. In this work, we studied the gamma-ray line features arising from the radioactive decay of heavy nuclei in the merger remnants based on the r-process nuclear reaction network and the astrophysical inputs derived from numerical relativity simulations. The decay chain of 50126 Sn (T 1/2 = 230 kyr) → 51126 Sb (T 1/2 = 12.35 days) → 52126 Te (stable) produces several bright gamma-ray lines with energies of 415, 667, and 695 keV, making it the most promising decay chain during the remnant phase. The photon fluxes of these bright gamma-ray lines reach ∼10−5 γ cm−2 s−1 for Galactic merger remnants with ages less than 100 kyr, which can be detected by the high energy resolution MeV gamma-ray detectors like the MASS mission.

The R-Process Alliance: 2MASS J22132050–5137385, the Star with the Highest-known r-process Enhancement at [Eu/Fe] = +2.45* * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

We present stellar parameters and chemical abundances of 47 elements detected in the bright (V = 11.63) very metal-poor ([Fe/H] = −2.20 ± 0.12) star 2MASS J22132050−5137385. We observed this star using the Magellan Inamori Kyocera Echelle spectrograph as part of ongoing work by the R-Process Alliance. The spectrum of 2MASS J22132050−5137385 exhibits unusually strong lines of elements heavier than the iron group, and our analysis reveals that these elements were produced by rapid neutron-capture (r-process) nucleosynthesis. We derive a europium enhancement, [Eu/Fe] = +2.45 ± 0.08, that is higher than any other r-process-enhanced star known at present. This star is only the eighth r-process-enhanced star where both thorium and uranium are detected, and we calculate the age of the r-process material, 13.6 ± 2.6 Gyr, from the radioactive decay of these isotopes. This star contains relatively large enhancements of elements that may be produced as transuranic fission fragments, and we propose a new method using this characteristic to assess the r-process yields and gas dilution in samples of r-process-enhanced stars. Assuming a canonical baryonic minihalo mass of 106 M ⊙ and a 1% metal retention rate, this star formed in a cloud of only ∼600 M ⊙. We conclude that 2MASS J22132050−5137385 exhibits a high level of r-process enhancement because it formed in an environment where the r-process material was less diluted than average.

Using 3H as a tracer to study streamflow components in large plain catchments on temperate climate

Abstract3H enters the hydrologic cycle after oxidizing in the 3H1HO molecule and it constitutes a very useful tracer for hydrological studies. One of these applications is streamflow component separation, which provides useful information to understand the hydrological cycle. This application is based on the fact that the contents in precipitation (runoff) tend to be markedly higher than those in groundwater (baseflow) because of decreasing activity in the last as a consequence of radioactive decay. The main objective of this paper is to test 3H for hydrograph separation in sub‐tropical South America, where it is favoured by high values in precipitation. The catchment of the Quequén Grande River, in Argentina, was selected. Total flow in surface water is a mixing between the baseflow and the event flow portion; the separation was done in three sections of the drainage network, and the proportion of baseflow were 36%, 88% and 47%.

Towards a precise measurement of 157Tb nuclear decay data: Sample purification using resonance ionization mass spectrometry

In nuclear physics, 157Tb emerges as a prime candidate for experiments aimed at elucidating neutrino mass constraints and at searching for sterile neutrinos. Despite its importance, 157Tb exhibits highly uncertain values for its nuclear decay properties. A significant challenge in many efforts to measure such data lies in the simultaneous undesired presence of 158Tb in the samples, which hinders precise activity determination. Mass separation emerges as a crucial method for obtaining pure 157Tb specimens. This work outlines the production of an isotopically-pure 157Tb sample through mass separation and ion implantation, using the RISIKO facility at the University of Mainz. The initial material was obtained from proton-irradiated Ta samples through radiochemical separation at the Paul Scherrer Institute. In total, a sample containing 8.7(9) · 1012 atoms of 157Tb was obtained. The efficiency of the mass separation and ion implantation was 13(2) %. The purified material served as the basis for new research endeavors at the Physikalisch Technische Bundesanstalt Braunschweig aiming at the determination of nuclear data for 157Tb with significantly improved precision.

Capturing Mercury-197m/g for Auger Electron Therapy and Cancer Theranostic with Sulfur-Containing Cyclen-Based Macrocycles.

The interest in mercury radioisotopes, 197mHg (t1/2 = 23.8 h) and 197gHg (t1/2 = 64.14 h), has recently been reignited by the dual diagnostic and therapeutic nature of their nuclear decays. These isotopes emit γ-rays suitable for single photon emission computed tomography imaging and Auger electrons which can be exploited for treating small and metastatic tumors. However, the clinical utilization of 197m/gHg radionuclides is obstructed by the lack of chelators capable of securely binding them to tumor-seeking vectors. This work aims to address this challenge by investigating a series of chemically tailored macrocyclic platforms with sulfur-containing side arms, namely, 1,4,7,10-tetrakis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO4S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO3S), and 1,7-bis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane-4,10-diacetic acid (DO2A2S). 1,4,7,10-Tetrazacyclododecane-1,4,7,10-tetracetic acid (DOTA), the widest explored chelator in nuclear medicine, and the nonfunctionalized backbone 1,4,7,10-tetrazacyclododecane (cyclen) were considered as well to shed light on the role of the sulfanyl arms in the metal coordination. To this purpose, a comprehensive experimental and theoretical study encompassing aqueous coordination chemistry investigations through potentiometry, nuclear magnetic resonance (NMR) spectroscopy, X-ray crystallography, and density functional theory (DFT) calculations, as well as concentration- and temperature-dependent [197m/gHg]Hg2+ radiolabeling and in vitro stability assays in human serum was conducted. The obtained results reveal that the investigated chelators rapidly complex Hg2+ in aqueous media, forming extremely thermodynamically stable 1:1 metal-to-ligand complexes with superior stabilities compared to those of DOTA or cyclen. These complexes exhibited 6- to 8-fold coordination environments, with donors statically bound to the metal center, as evidenced by the presence of 1H-199Hg spin-spin coupling via NMR. A similar octacoordinated environment was also found for DOTA in both solution and solid state, but in this case, multiple slowly exchanging conformers were detected at ambient temperature. The sulfur-rich ligands quantitatively incorporate cyclotron-produced [197m/gHg]Hg2+ under relatively mild reaction conditions (pH = 7 and T = 50 °C), with the resulting radioactive complexes exhibiting decent stability in human serum (up to 75% after 24 h). By developing viable chelators and understanding the impact of structural modifications, our research addresses the scarcity of suitable chelating agents for 197m/gHg, offering promise for its future in vivo application as a theranostic Auger-emitter radiometal.

Implementation of Chernobyl optimization algorithm based feature selection approach to predict software defects

Background Software defects can have catastrophic consequences. Therefore, fixing these defects is crucial for the evolution of software. Software Defect Prediction (SDP) enables developers to investigate unscramble faults in the inaugural parts of the software progression mechanism. However, SDP faces many challenges, including the high magnitude of attributes in the datasets, which can degrade the prognostic performance of a defect forecasting model. Feature selection (FS), a compelling instrument for overcoming high dimensionality, selects only the relevant and best features while carefully discarding others. Over the years, several meta-heuristic algorithms such as the Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Differential Evolution (DE), and Ant Colony Optimization (ACO) have been used to develop defect prediction models. However, these models suffer from several drawbacks, such as high cost, local optima trap, lower convergence rate, and higher parameter tuning. To overcome the above shortcomings, this study aims to develop an innovative FS technique, namely, the Chernobyl Optimization Algorithm (FSCOA), to unwrap the most informative features that can produce a precise prediction model while minimizing errors. Methods The proposed FSCOA approach mimicked the process of nuclear radiation while attacking humans after an explosion. The proposed FSCOA approach was combined with four widely used classifiers, namely Decision Tree (DT), K-nearest neighbor (KNN), Naive Bayes (NB), and Quantitative Discriminant Analysis (QDA), to determine the finest attributes from the SDP datasets. Furthermore, the accuracy of the recommended FSCOA method is correlated with existing FS techniques, such as FSDE, FSPSO, FSACO, and FSGA. The statistical merit of the proposed measure was verified using Friedman and Holm tests. Results The experimental findings showed that the proposed FSCOA approach yielded the best accuracy in most cases and achieved an average rank of 1.75, followed by the other studied FS approaches. Furthermore, the Holm test showed that the p-value was lower than or equivalent to the value of α/(A-i), except for the FSCOA and FSGA and FSCOA and FSACO models. Conclusion The experimental findings showed that the prospective FSCOA procedure eclipsed alternative FS techniques with higher accuracy in almost all cases while selecting optimal features.

Modeling the Progenitor Stars of Observed Type IIP Supernovae

Type IIP supernovae (SNe IIP) are thought to originate from the explosion of massive stars >10 M ⊙. Their luminosity is primarily powered by the explosion energy and the radioactive decay energy of 56Co, with the photosphere location regulated by hydrogen recombination. However, the physical connections between SNe IIP and their progenitor stars remain unclear. This paper presents a comprehensive study of SNe IIP and their progenitor stars by using the one-dimensional stellar evolution code, MESA. Our model grids consider the effects of stellar metallicity, mass, and rotation in the evolution of massive stars, as well as the explosion energy and 56Ni production in modeling supernovae. To elucidate the observed SNe IIP and their origins, we compare their light curves (LCs) with our models. Furthermore, we investigate the impact of stellar parameters on LCs by considering stellar mass, metallicity, rotation, explosion energy, and 56Ni production. We find that more massive stars exhibit longer plateaus due to increased photon diffusion time caused by massive ejecta. Higher metallicity leads to increased opacity and mass loss of progenitor stars. Rapid rotation affects internal stellar structures, enhancing convective mixing and mass loss, potentially affecting the plateau’s brightness and duration. Higher explosion energy results in brighter but shorter plateaus due to faster-moving ejecta. 56Ni mass affects late-time luminosity and plateau duration, with larger masses leading to slower declines.

The thermalization of γ-rays in radioactive expanding ejecta: a simple model and its application for Kilonovae and Ia SNe

ABSTRACT A semi-analytic approximation is derived for the time-dependent fraction $f_\gamma (t)$ of the energy deposited by radioactive decay $\gamma$-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 per cent and 10 per cent accuracy, respectively, the energy deposition rates, $\dot{Q}_{\rm dep}$, obtained in numeric Monte Carlo calculations. The time $t_\gamma$ beyond which $\gamma$-ray deposition is inefficient is determined by an effective frequency-independent $\gamma$-ray opacity $\kappa _{\gamma ,\text{eff}}$, $t_\gamma = \sqrt{\kappa _{\gamma ,\text{eff}}\langle \Sigma \rangle t^2}$, where $\langle \Sigma \rangle \propto t^{-2}$ is the average plasma column density. For $\beta$-decay dominated energy release, $\kappa _{\gamma ,\text{eff}}$ is typically close to the effective Compton scattering opacity, $\kappa _{\gamma ,\text{eff}} \approx 0.025$ cm$^{2}$ g$^{-1}$ with a weak dependence on composition. For KNe, $\kappa _{\gamma ,\text{eff}}$ depends mainly on the initial electron fraction $Y_e$, $\kappa _{\gamma ,\text{eff}} \approx 0.03(0.05)$ cm$^{2}$ g$^{-1}$ for $Y_e \gtrsim (\lesssim) 0.25$ (in contrast with earlier work that found $\kappa _{\gamma ,\text{eff}}$ larger by 1–2 orders of magnitude for low $Y_e$), and is insensitive to the (large) nuclear physics uncertainties. Determining $t_\gamma$ from observations will therefore measure the ejecta $\langle \Sigma \rangle t^2$, providing a stringent test of models. For $\langle \Sigma \rangle t^2=2\times 10^{11}~{\rm g\, {cm}^{-2}\, s^2}$, a typical value expected for KNe, $t_\gamma \approx 1$ d.

Unintended Consequences of Urban Expansion and Gold Mining: Elevated Indoor Radon Levels in Gauteng Communities’ Neighboring Gold Mine Tailings

The province of Gauteng in South Africa has a rich history of gold mining, which has driven economic growth and urbanization. Gold mining has also created over 270 gold mine tailings (GMT), now surrounded by human settlements due to a housing shortage. These GMT pose a health risk as they harbor elevated uranium, which over time undergoes radioactive decay to produce radon, a known lung carcinogen. This study aimed to investigate the potential correlation between the proximity to gold mine tailings (GMT) and indoor radon concentrations in Gauteng’s residential dwellings. Volume activity of radon (VAR) inside 330 residential dwellings was measured in residential dwellings located proximally (<2 km) and distally (>2 km) to gold mine tailings using AlphaE radon monitors during winter. An interviewer-administered questionnaire was utilized to obtain data on factors that may influence indoor radon activities. Descriptive statistics and bivariate logistic regression analyzed the influence of proximity to gold mine tailings and dwelling characteristics on VAR. Furthermore, VAR was compared to the World Health Organization (WHO) radon reference level of 100 Bq/m3. Residential dwellings near gold mine tailings had significantly higher average indoor radon concentrations (103.30 Bq/m3) compared to the control group (65.19 Bq/m3). Residential dwellings proximal to gold mine tailings were three times more likely to have VAR beyond the WHO reference level of 100 Bq/m3. Furthermore, they had estimated annual effective doses of 2.60 mSv/y compared to 1.64 mSv/y for the control group. This study highlighted a concerning association between proximity to gold mine tailings and elevated indoor radon levels. Public health interventions prioritizing residential dwellings near gold mine tailings are crucial. Educational campaigns and financial assistance for radon mitigation systems in high-risk dwellings are recommended. Residents near gold mine tailings are encouraged to ensure continuous natural ventilation through frequent opening of windows and doors.

Generalized eikonal identities for charged currents

We discuss QED radiative corrections to contact operators coupling two heavy fields and one light field. These operators appear ubiquitously in weak interactions with nuclei such as beta decay and neutrino nucleus scattering. New eikonal identities are derived in the static limit (i.e., neglecting nuclear recoil) that allow for manifest power counting of enhancements proportional to the charge of the nucleus. We apply these new identities to nuclear beta decays and find that the “independent particle model” used by Jaus, Rasche, Sirlin & Zucchini is closely related, though not identical, to a model independent effective field theorcalculation.

SN 2019tua: A Type IIb Supernova with Multiple Bumps in the Light Curves

We present photometric and spectroscopic observations and analysis of the Type IIb supernova (SN) SN 2019tua, which exhibits multiple bumps in its declining light curves between 40 and 65 days after discovery. SN 2019tua shows a time to peak of about 25 days, similar to other Type IIb SNe. Our observations indicate a decrease in its brightness of about 1 mag in the 60 days after the peak. At about days 50 and 60, its multiband light curves exhibit bumpy behavior. The complex luminosity evolution of SN 2019tua could not be well modeled with a single currently popular energy source model, e.g., radioactive decay of 56Ni, magnetar, interaction between the ejecta and a circumstellar shell. Even though the magnetar model has a smaller χ 2/dof value, the complex changes in SN 2019tua’s brightness suggest that more than one physical process might be involved. We propose a hybrid circumstellar medium (CSM) interaction plus 56Ni model to explain the bolometric light curve of SN 2019tua. The fitting results show that the ejecta mass M ej ≈ 2.4 M ⊙, the total CSM mass M CSM ≈ 1.0 M ⊙, and the 56Ni mass M Ni ≈ 0.4 M ⊙. The total kinetic energy of the ejecta is E k ≈ 0.5 × 1051 erg. Preexisting multiple shells suggest that the progenitor of SN 2019tua experienced mass ejections within approximately ∼6–44 yr prior to the explosion.