Decay Chain Research Articles (Page 1)

Alternative production of Lead-203: Optimizing production, purification, and radiolabelling for enhanced theranostic applications.

BackgroundTargeted alpha therapy (TAT) utilizing high-LET alpha particles from radionuclides like 225Ac and 227Th shows promise in cancer treatment due to their ability to induce dense, localized DNA damage. This study uses the Geant4-DNA Monte Carlo toolkit to simulate DNA damage and evaluate the radiobiological effects of 225Ac and 227Th.ResultsThe simulations revealed that both 225Ac and 227Th induce significant DNA damage, particularly complex double-strand breaks (DSBs), with 227Th producing slightly more clustered damage due to its longer decay chain and higher alpha energy. The study also found that both radionuclides exhibited elevated Relative Biological Effectiveness (RBE), especially for complex DSBs. Cell survival analysis showed a sharp decline in viability, consistent with the clustered damage patterns induced by alpha emissions.ConclusionsThese findings underscore the potential of 225Ac and 227Th in targeted radionuclide therapy, particularly for tumors resistant to conventional treatments. The high RBE and complex DNA damage induced by these radionuclides suggest they could enhance therapeutic efficacy when combined with other treatment modalities, such as chemotherapy or immunotherapy, and may benefit patients with tumors exhibiting high DNA repair capacity. This study provides valuable insights for optimizing TAT protocols and advancing the clinical translation of 225Ac and 227Th therapies.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40658-025-00805-9.

A search for exotic decays of the Higgs boson H into new scalar or pseudoscalar particles that subsequently decay into b-quarks is presented. The search considers ZH production with several decay scenarios for the Higgs boson; first to a pair of identical scalars, H→2a→4b, second to a pair of scalars with different masses (ma1<ma2), either directly, H→a1a2→4b, or via a longer decay chain, H→a1a2→3a1→6b. The analysis uses proton-proton collision data at s=13 TeV collected with the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb−1. No significant excess above the Standard Model prediction is observed. The search sets upper limits at 95% confidence level on the ratio of the Higgs boson production cross section to the SM prediction times the branching ratio of Higgs bosons decaying into 4b or 6b, between 4% and 25% for σ(ZH)/σSM(ZH)×B(H→2a→4b), between 24% and 38% for σ(ZH)/σSM(ZH)×B(H→a1a2→4b), and between 10% and 20% for σ(ZH)/σSM(ZH)×B(H→a1a2→3a1→6b), depending on the masses of the scalar particles.

This study introduces a hybrid approach integrating advanced plasmonic nanomaterials and machine learning (ML) for high-precision biomolecule detection. We leverage aluminum concave nanocubes (AlCNCs) as an innovative plasmonic substrate to enhance the native fluorescence of neurotransmitters, including dopamine (DA), norepinephrine (NE), and 3,4-dihydroxyphenylacetic acid (DOPAC). AlCNCs amplify weak fluorescence signals, enabling probe-free, label-free detection and differentiation of these molecules with great sensitivity and specificity. To further improve classification accuracy, we employ ML algorithms, with Long Short-Term Memory (LSTM) networks playing a central role in analyzing time-dependent fluorescence data. Comparative evaluations with k-nearest neighbors (KNN) and Random Forest (RF) demonstrate the superior performance of LSTM in distinguishing neurotransmitters. The results reveal that AlCNC substrates provide up to a 12-fold enhancement in fluorescence intensity for DA, 9-fold for NE, and 7-fold for DOPAC compared to silicon substrates. At the same time, ML algorithms achieve classification accuracy exceeding 89%. This interdisciplinary methodology bridges the gap between nanotechnology and ML, showcasing the synergistic potential of AlCNC-enhanced native fluorescence and ML in biosensing. The framework paves the way for probe-free, label-free biomolecule profiling, offering transformative implications for biomedical diagnostics and neuroscience research.

Producing several alpha-emitting isotopes in the decay chain of 227Th-based radiopharmaceuticals has increased the complexity of determining the optimal therapeutic dose. This research aims to assess the contribution of each thorium progeny to the cumulative dose in the tumor over time. This assessment will help determine the required injected activity and the appropriate characteristics of a 227Th-based radiopharmaceutical that can provide an adequate dose to induce sufficient cytotoxicity for effective treatment. The cumulative dose in tumors of various sizes (with radii of 0.6, 1.2, and 1.8cm) resulting from the decay of 227Th was calculated using MCNPX. The radial and temporal distribution of the absorbed dose within the tumor was studied, along with the contribution of each radioisotope to the cumulative dose over time throughout the tumor. Validation of the calculation was performed by determining the cumulative dose of 227Th-rituximab based on the experimental biodistribution, tumor size and mice weight reported in the literature. The cumulative dose within the tumor increases over time and is inversely proportional to the tumor's volume. The radial distribution of the cumulative dose within the tumor indicated that 227Th-based radiopharmaceuticals do not harm the healthy tissue surrounding the tumor. By taking into account the size of the tumor and the required therapeutic dose, the proposed calculation method can be employed to determine the necessary injected activity and characteristics of a radiopharmaceutical. This includes identifying a suitable retention time and tumor uptake to improve therapeutic outcomes.

Brazil’s titanium dioxide production generates approximately 30,000 tons of waste annually, known as unreacted ore waste (UOW), which is currently disposed of in industrial landfills. This residue is enriched with naturally occurring radionuclides from the uranium and thorium decay series and is classified as Naturally Occurring Radioactive Material (NORM). The reuse of NORM residues in building materials is only permissible if the activity concentrations of radionuclides in the final product do not pose any additional exposure risk to individuals. Radiation exposure from such materials may be classified as external—due to direct gamma irradiation—or internal—resulting from inhalation of radon (222Rn) and its short-lived decay products. In a previous study, the authors assessed both internal and external indoor exposure associated with incorporating up to 23% of UOW into cement and interlocking blocks. This study evaluates the feasibility of using these materials in outdoor applications, with particular emphasis on radionuclide leaching potential and external radiological exposure. Cement and interlocking blocks containing varying proportions of unreacted ore waste (0%, 3.5%, and 23%) were subjected to weathering for 60 days. The activity concentrations of 238U, 226Ra, 210Pb, 232Th, 228Ra, and 40K in the leachate were measured using gamma spectrometry and spectrophotometry. No significant increase in radionuclide concentrations were observed in the leachate from blocks containing 3.5% and 23% UOW compared to those without any residue. Gamma radiation exposure remained consistently below 0.1 mSv, and no notable changes were detected in radon concentrations in the vicinity of the experiment. The results indicate that incorporating up to 23% UOW in cement and interlocking blocks is safe and compliant with regulatory limits related to groundwater contamination and human exposure when using these materials in an open air environment.

ABSTRACT This study aims to evaluate the radiation doses from building materials, including sand, cement, brick, faience, plaster and marble, collected from different sites in eastern Algeria. The specific activities of natural radionuclides, mainly represented by the natural radioactive series 238U, 232Th and primordial 40K, were determined using a gamma spectrometry system equipped with a high purity germanium (HPGe) detector. Radiological hazard parameters (Raeq, Hex, Hin, Iγ and Iα) associated with these activities were calculated to determine the suitability of the construction materials. To assess their radiological risks to human health, an analysis of absorbed dose rate (D), annual effective dose (AED) and excess lifetime cancer risk (ELCR) was performed and the results examined and compared with those reported elsewhere. The findings obtained for these samples are within the limits of internationally recommended values.

Gamma ray tool used for petrophysical analysis in Oil & Gas industry is for natural radioactivity in rocks in subsurface. Potassium (40K), uranium (236U) and thorium (232Th) are three decay series of isotopes are abundant in rocks and are detected by Natural Gamma Ray Spectrometry (NGS) tool. Potassium, thorium and uranium spectra of Gamma ray is obtained by NGS tool with NaI crystal of photo multiplier tube. NGS tool has five windows for counting the gamma rays of low energy and high energy level. Tool has a master calibration in Clamart (France). Secondary calibrators are used to check the operation of the tool and its stability. Natural Gamma Ray Spectrometry measures the contribution of gamma ray of each individual series of Thorium, Uranium and Potassium separately. Also, it measures concentration of Thorium and Uranium in ppm and potassium in percentage in any rock. Applications of NGS are many folds. This is very good shale indicator. Also, it differentiates between shale and potassium salts (Evaporites) with help of cross plots of K% versus bulk density, neutron porosity and sonic transit time. From the ratio of Th/K obtained from NGS tool against rocks, it distinguishes feldspathic sandstone, micaceous sandstone or quartzite sandstone. Feldspar contain high potassium and low thorium as a result Th/K ratio is very low against Feldspathic sandstone whereas the ratio is high in Micaceous sandstone due to high thorium in mica and low potassium. NGS tool play an important role to find the origin of carbonate either in pure chemical origin or organic by measuring the uranium. Low uranium indicates it is of chemical origin whereas rich content of uranium in carbonate indicates it is reducing environment and of organic origin. NGS also shows Th/K ratio abruptly high in case of unconformities. It is possible to find the organic content from measurement of uranium and from that its hydrocarbon potential in source rock after proper calibration with core data.

Recently, the new structure G(3900) observed by the BESIII Collaboration in the e+e−→DD¯ was identified to be the P-wave DD¯*/D¯D* vector molecular resonance using a unified meson exchange model. Apart from the vector P-wave state, a possible pseudoscalar P-wave molecular state of the DD¯*/D¯D* [called G0(3900) for short] was also predicted, which is likely to be observed in future experiments. Within the molecular framework, we calculated the partial decay widths for a series of hadronic decays of the G0, including G0→ω(ρ0)J/ψ, π+π−ηc(1S), π+π−χc1(1P), and D0D¯0π0. Under present model parameters, the hidden-charm decay modes are dominated by the G0→ωJ/ψ and G0→π+π−ηc(1S), and the partial widths can reach 1 MeV and 0.1 MeV, respectively. The open-charm channel G0→D0D¯0π0 exhibits a rather small decay rate (∼0.1 keV). In terms of our present predictions, we suggest BESIII and Belle II to search for the pseudoscalar P-wave DD¯*/D¯D* molecular state with JPC=0−+ in the hidden-charm processes G0→ωJ/ψ or G0→π+π−ηc(1S).

Radon escape effect on its progeny's activity in naturally occurring radionuclide decay series.

Orthodontists frequently use elastomeric chains for space closure and incisor retraction, though these chains are prone to force degradation and permanent deformation over time. Initially introduced in the early 20th century, elastic power chains became more widely adopted in orthodontic practice in the 1960s due to industrial advancements. There are three main types of elastomeric chains: closed (continuous), open (short), and long (broad), available in various colors such as clear and black. Elastomeric chains generate forces for several orthodontic applications, including traction of impacted teeth, space closure, midline correction, retraction of canines and incisors post-extraction, tooth leveling and alignment, mesial displacement in posterior regions, and space closure. However, therapeutic control challenges arise as the force exerted by these chains diminishes over time, with studies indicating a reduction of 50%–75% in the first 24 hours, followed by continued exponential decay.OBJECTIVES:This study aimed to analyze the rate of force decay in closed and open power chains, both black and transparent, from four orthodontic manufacturers (American Orthodontics®, Ortho Technology®, Ormco®, and Orthometric®). Additionally, we sought to determine any significant differences among brands and colors that could influence the elastics’ clinical effectiveness.MATERIALS AND METHODS:A total of 48 power chain samples were tested for force decay by using a universal orthodontic force gauge. The chains, stretched to 90 mm (twice their original length), were measured at 0 hours, 24 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, and 5 weeks. The samples were stored in artificial saliva within a laboratory water bath at a constant 37°C to simulate the oral environment. Tukey’s honestly significant difference (HSD) test was applied to assess differences between brands, colors, types (closed or open), and time intervals.RESULTS:The study revealed significant differences in force decay among the various orthodontic power chains over the 5-week evaluation period. American Orthodontics® demonstrated the highest reduction in force, with a decay of 73.42% by week 5, while Ormco® exhibited the least decay at 48.17%. The black power chains of American Orthodontics® and Ortho Technology® showed superior initial force retention compared to their clear power chains counterparts, although all tested materials experienced substantial force decay. Closed power chains consistently retained higher forces than open ones across all brands, highlighting their potential advantage in clinical applications requiring optimal force delivery.DISCUSSION:The significant differences in decay patterns suggest that clinicians should consider using Ormco® and Orthometric® for prolonged applications due to its relative stability, while the black power chains of American Orthodontics® and Ortho Technology® may be more suitable for cases requiring immediate, high forces. Additionally, the consistent superiority of closed power chains in force retention emphasizes their potential advantages in optimizing tooth movement, reinforcing the need for orthodontists to align material choices with specific clinical objectives.CONCLUSION:This study highlights the significant variability in force decay among different orthodontic power chains, emphasizing the necessity for careful material selection based on both initial strength and long-term performance. The findings advocate for tailored approaches to enhance treatment efficacy and patient outcomes in orthodontic care.

Abstract. We describe environmental gamma spectrometry data for >700 soil samples collected from >35 high-resolution quantitative soil profiles spanning global sites. The data are collected for the purpose of modern soil chronometry based on fallout radionuclides (FRNs) 7Be and 210Pb, using the Linked Radionuclide Accumulation model (LRC). Cumulative gamma counting time for samples in the database exceeds 6.5 years. This is a living database to be augmented as data become available and corrected with improvements in data reduction, or identification of errors. Versions and changes will be indexed. Special attention is paid to measurement uncertainties in the dataset, and to how atmospheric or excess 210Pb is defined in both geochemical and mathematical terms for use in the LRC model. Basic familiarity with gamma spectrometry and radionuclide decay chains is assumed. The data set can be accessed at https://doi.org/10.17632/cfxkpn6hj9.1 (Landis, 2025).

The strategic importance of metals found in deep-sea polymetallic nodules has spurred a surge in interest for their exploitation. However, nodules are known to incorporate radionuclides during their growth, so that any industrial processing would involve classifying them as naturally occurring radioactive materials (NORM). As the start of deep-sea mining gets closer, concerns about elevated exposure to radiation that could result from the handling of nodules has recently been raised. In this study, we address this issue within the framework of radiation protection regulations. For the first time, we present estimates of effective doses associated with laboratory work and industrial-scale exploitation, transportation and metallurgical processing of polymetallic nodules. Estimates are based on an analysis of all long-lived radionuclides from the three natural decay chains of uranium-238, uranium-235 and thorium-232 and on radon exhalation rates from dry nodules. We show that effective doses for laboratory workplaces are well below the threshold of 1 millisievert per calendar year (mSv/a) for occupational exposure, even under the most conservative assumptions. Furthermore, we find that the effective doses for personnel on nodule transport vessels and metallurgical processing facilities may exceed the threshold in a conservative scenario. However, with standard radiation protection and mitigation measures common in other NORM-affected industries, effective doses can be kept well below the occupational exposure limit.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-10842-0.

Abstract Type Ia supernovae (SNe Ia) are powered by the radioactive decay of isotopes such as 56Ni and 56Co, making their γ-ray spectra useful probes of the explosion mechanism and ejecta structure. Accurate interpretation of γ-ray observables, including line ratios and continuum fluxes, requires a detailed understanding of the microphysical processes that shape the spectra. One such process is positronium formation during electron–positron annihilation, which can redistribute flux from the 511 keV line into the surrounding continuum. To assess the impact of positronium on the emergent spectra, we developed a new open-source module, tardis-He, for time-dependent three-dimensional γ-ray transport, integrated into the radiative transfer code tardis. The code simulates γ-ray spectra and light curves from one-dimensional supernova ejecta models and allows for flexible incorporation of decay chains and opacity treatments. Using tardis-He, we explore the effect of positronium formation by varying the positronium fraction from 0% to 100%, and assuming an extreme case where 75% of positronium decays result in three-photon emission. We find that full positronium formation can reduce the 511 keV line flux by ≈70% and modestly enhance energy deposition by up to 2% at around 100 days postexplosion, compared to models without positronium. These results demonstrate that, while the effect is not dominant, positronium formation introduces measurable changes to γ-ray observables. Future observations with missions such as the Compton Spectrometer and Imager may offer constraints on positronium formation in SNe Ia and help refine models of their radioactive energy transport.

The daughter nuclides in the long decay chain have clouded the translation of the corresponding α-radionuclide therapy. To achieve radioactivity confinement is, therefore, pivotal to the development of medical α-radiopharmaceuticals. Here, we proposed coordination confinement on the decay chains of medical α-radionuclides, employing a versatile crown-ether ligand to adaptively chelate with the decay daughters of typical medical α-radionuclides. The coordination interaction between dibenzo-18-crown-6 (dibenzo-18Cr6) and the decay daughters, i.e., Fr (221Fr), At (217At), Bi (211-213Bi), Po (211-213Po, 215-216Po), Tl (207-209Tl), and Pb (207-209,212/213Pb), from the decay chains of 212Pb/212Bi, 213Bi, 223/224Ra, and 225Ac, has been probed through combined computational and experimental chemistry, and all the results suggest that dibenzo-18Cr6 can form a nuclide trap as a multifunctional chelator to capture different decay daughters. Most importantly, dibenzo-18Cr6-mediated coordination confinement on the decay daughters in vivo has been demonstrated via an 225Ac-labeled radiopharmaceutical, highlighting excellent tumor suppression effects and reliable safety. This work unveils the great potential of decay-chain-adaptive coordination in improving the biosafety of targeted α-therapy, particularly in addressing the unwanted migration of daughter radionuclides of α-emitting endoradiotherapy in clinical practice.

Lignite coal is the primary local energy source in Türkiye. The inevitable result of the utilization of lignite coal in thermal power plants for electricity generation is the formation of large amounts of ash (bottom ash and fly ash) as industrial solid waste. These wastes contain technologically enhanced natural radionuclides in the uranium (238U) and thorium (232Th) decay series and radio-potassium (40K). Seyitömer lignite-fired thermal power plant (4 × 150MW) located in the Central Western Anatolia Region of Türkiye produces approximately 1.6 million tons of siliceous fly ash per year. In this study, the utilization of these fly ashes in the construction industry and their storage in ash landfill areas were assessed by estimating radiological parameters and using the RESRAD Onsite 7.2 computer code. For this, the enhanced natural radioactivity levels of fly ash samples were determined by gamma-ray spectrometry with a high-purity germanium detector. The average activity concentrations of the natural radionuclides measured in fly ash samples were 621 ± 25 (40K), 150 ± 7 (226Ra), and 96 ± 3 (232Th) Bq/kg. The assessment results confirm that the studied fly ash samples are radiologically safe to be used in cement and concrete production in accordance with international and national standards without significant effects of radiological hazards. The RESRAD simulation results revealed that the total annual effective dose rate in the uncovered ash storage area reached its maximum (0.11mSv/y) at 18.97years, and the covering of the protective materials on top of the area significantly attenuated the gamma radiation in the decreasing order: concrete > soil > PVC > zeolite.

Estimating the postmortem interval (PMI)–the time since death–remains a longstanding challenge in forensic and biological sciences due to the complex influence of environmental and physiological variables. Here, we present a novel computational framework that leverages the physical principles of radioactive decay to estimate PMI using the relative isotope abundances of radon progeny (^{210}textrm{Pb}, ^{210}textrm{Bi}, and ^{210}textrm{Po}) in biological tissue. Our approach models the decay chain of inhaled ^{222}textrm{Rn} and solves the associated system of differential equations to determine PMI based on isotope ratio dynamics. A key innovation is the use of paired measurements taken at two postmortem time points to capture the time-derivative of the decay curve, enhancing solution uniqueness, reducing dependence on prior exposure history, therefore minimizing error. Monte Carlo simulations were employed to assess model performance. If validated empirically, this approach lays the groundwork for a physics-based method for PMI estimation with potential applications in forensic science and radiation biology.

Abstract Secondary ionization mass spectrometry (SIMS) is a powerful tool for precise correlative actinide decay chain dating, trace element analysis, and stable isotope analysis of accessory minerals at unrivaled nanogram-scale sampling. Matrix-matched reference materials are a prerequisite for accurate quantification of isotopic compositions by SIMS. For rock-forming and accessory minerals showing partial or complete solid solution, elaborate correction schemes are required for SIMS isotope analysis. Natural zircon (ZrSiO4), often with a nearly stoichiometric endmember composition, has traditionally required less attention to matrix matching between reference materials and unknowns. However, with increasing analytical precision afforded by multi-collection SIMS instrumentation, it becomes important to experimentally verify this assumption and define its limitations. Here, we focus on Hf in zircon (Zrn), which is isomorphous with hafnon (Hfn), and the fourth most abundant element in natural zircon. Two endmembers in the Zrn-Hfn solid solution and three intermediate compositions were synthesized in a MoO2–LiMoO4 flux. Oxygen isotopic compositions of synthetic Zrn-Hfn crystals were determined at the milligram scale by laser fluorination isotope ratio mass spectrometry, and at lateral and depth resolutions of ∼15 μm and ∼1 μm, respectively, by SIMS. Despite a detected ∼1–3‰ isotopic heterogeneity in flux-grown Zrn-Hfn, a strong correlation between instrumental mass fractionation and the zirconium number Zr# % (atomic Zr/[Zr + Hf] × 100) was observed (Pearson correlation coefficient r = 0.9958), with ∼8.8‰ variation in δ18O across the compositional range. For most natural zircon, including common reference materials, the interpolated matrix effect is smaller than typical analytical uncertainties for individual SIMS spots (∼0.1‰). Only δ18O analysis of Hf-rich pegmatite zircon by SIMS requires significant (up to ∼3‰) matrix corrections. In such cases, the matrix effect on instrumental mass fractionation can be linearly interpolated between a common low-Hf zircon reference and the synthetic Hfn endmember to within ∼0.1–0.2‰ uncertainty.

Preparation and homogeneity of a monazite sand matrix: A candidate reference material for activity concentration measurements 40K, 226Ra, 228Ra and 214Pb.

The tin processing and refining industry produces by-products in the form of tin slag 2. The radioactive content from uranium and thorium decay series in tin slag 2 still poses a challenge in the management or utilization of tin slag 2. Current options for managing by-products from the tin processing and refining industry, such as tin slag 2, are still limited to temporary storage. This study aims to simulate the use of tin slag 2 as a fine aggregate mixture in building mortar, particularly as a plastering material. The dose analysis of the use of mortar-tin slag 2 has been compared using two methods, simulation with RESRAD-BUILD software and manual calculations. The concentrations of measured radionuclide activity 226Ra, 228Ra, 228Th, and potassium were 5.7 Bq/gram, 16.6 Bq/gram, 14.3 Bq/gram, and 1.16 Bq/gram, respectively. These results indicate that several radionuclides exceed the limits of 1 Bq/gram as stipulated in the regulations for the uranium and thorium decay series radionuclide or 10 Bq/g for potassium. Initial screening analysis using the activity concentration index was carried out to see the risk of exposure caused by tin slag 2. The activity concentration index of tin slag 2 was obtained with a value of 90, which exceeded the reference level of 1. Simulation with RESRAD-BUILD software with scenario one room size 4x3x2.5 m, and two variations of plaster thickness (1 and 1.5 cm). With thicker plastering, the dose simulation increased, and a dose of 18.6 mSv/year was obtained. The second method, namely manual calculation according to the EN 17637:2022 standard, involves two scenarios. The first approach, mortar-tin slag 2, is made in plastering without considering other materials. The second approach is mortar-tin slag 2 as a superficial material and using other additional materials (bulk material). From the two manual calculation approaches, the highest dose was obtained at 11.24 mSv/year. Dose analysis through RESRAD-BUILD simulation and manual calculations showed a correlation with the activity concentration index, with a dose of more than 1 mSv/year. However, the dose values obtained have quite significant differences. The difference in the calculation results requires further review to determine which parameters influence it. Keywords: tin slag 2, partial mixture, simulation, RESRAD-BUILD software, doses