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We report on a new measurement of the half-life of 42Ar by following its decay over a time period of more than 13 years using γ-ray spectrometry. The obtained value of (39.5 ± 3.6) y confirms the only other, previously measured value of (33 ± 2) y. However, since partial outgassing of the accumulated Ar from the sample cannot be excluded, this value should be understood as a lower limit. The sample has now been stored in a gas-tight quartz ampoule to enable further measurements excluding the outgas effect in order to confirm our finding. [ABSTRACT FROM AUTHOR]

BOLD-100 (formerly IT-139, KP1339), a well-established chemotherapeutic agent, is currently being investigated in clinical trials for the treatment of gastric, pancreatic, colorectal, and bile duct cancer. Despite numerous studies, the exact mode of action is still the subject of discussions. Radiolabeled BOLD-100 could be a powerful tool to clarify pharmacokinetic pathways of the compound and to predict therapy responses in patients using nuclear molecular imaging prior to the therapy. In this study, the radiosyntheses of carrier-added (c.a.) [97/103Ru]BOLD-100 were performed with the two ruthenium isotopes ruthenium-103 (103Ru; β−, γ) and ruthenium-97 (97Ru; EC, γ), of which in particular the latter isotope is suitable for imaging by single-photon emission computed tomography (SPECT). To identify the best tumor-to-background ratio for diagnostic imaging, biodistribution studies were performed with two different injected doses of c.a. [103Ru]BOLD-100 (3 and 30 mg kg−1) in Balb/c mice bearing CT26 allografts over a time period of 72 h. Additionally, ex vivo autoradiography of the tumors (24 h p.i.) was conducted. Our results indicate that the higher injected dose (30 mg kg−1) leads to more unspecific accumulation of the compound in non-targeted tissue, which is likely due to an overload of the albumin transport system. It was also shown that lower amounts of injected c.a. [103Ru]BOLD-100 resulted in a relatively higher tumor uptake and, therefore, a better tumor-to-background ratio, which are encouraging results for future imaging studies using c.a. [97Ru]BOLD-100. [ABSTRACT FROM AUTHOR]

The radioactive nuclide 225Ac is one of the few promising candidates for cancer treatment by targeted-α\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\alpha$$\end{document}-therapy, but worldwide production of 225Ac faces significant limitations. In this work, the Isotope Separation On-Line method was used to produce actinium by irradiating targets made of uranium carbide and thorium carbide with 1.4-GeV protons. Actinium fluoride molecules were formed, ionized through electron impact, then extracted and mass-separated as a beam of molecular ions. The composition of the mass-selected ion beam was verified using time-of-flight mass spectrometry, α\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\alpha$$\end{document}- and γ\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\gamma$$\end{document}-ray decay spectrometry. Extracted quantities of 225Ac19F2+\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{225}\textrm{Ac}^{19}\textrm{F}_2^{+}$$\end{document} particles per μ\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\upmu$$\end{document}C of incident protons were 3.9(3)×107\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$3.9(3)\times 10^7$$\end{document} from a uranium carbide target and 4.3(4)×107\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$4.3(4)\times 10^7$$\end{document} for a thorium carbide target. Using a magnetic mass separator, the long-lived contamination 227 Ac is suppressed to <5.47×10-7\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$<5.47\times 10^{-7}$$\end{document} (95% confidence interval) with respect to 225Ac by activity. Measured rates scale to collections of 108 kBqμ\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\upmu$$\end{document}A-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-1}$$\end{document}h-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-1}$$\end{document} of directly produced 225Ac19F2+\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{225}\textrm{Ac}^{19}\textrm{F}_2^{+}$$\end{document}. [ABSTRACT FROM AUTHOR]

Background: Targeted radionuclide therapy with 177 Lu-labelled small conjugates is expanding rapidly, and its success is linked to appropriate patient selection. Companion diagnostic conjugates are usually labelled with 68 Ga, offering good imaging up to ≈2 h post-injection. However, the optimal tumor-to-background ratio is often reached later. This study examined promising positron-emitting radiometals with half-lives between 3 h and 24 h and β + intensity (I β+ ) ≥ 15% and compared them to 68 Ga. The radiometals included: 43 Sc, 44 Sc, 45 Ti, 55 Co, 61 Cu, 64 Cu, 66 Ga, 85m Y, 86 Y, 90 Nb, 132 La, 150 Tb and 152 Tb. 133 La (7.2% I β+ ) was also examined because it was recently discussed, in combination with 132 La, as a possible diagnostic match for 225 Ac., Methods: Total electron and photon doses per decay and per positron; possibly interfering γ-ray emissions; typical activities to be injected for same-day imaging; positron range; and available production routes were examined., Results: For each annihilation process useful for PET imaging, the total energy released (MeV) is: 45 Ti (1.5), 43 Sc (1.6), 61 Cu and 64 Cu (1.8), 68 Ga (1.9), 44 Sc and 133 La (2.9), 55 Co (3.2), 85m Y (3.3), 132 La (4.8), 152 Tb (6.5), 150 Tb (7.1), 90 Nb (8.6), and 86 Y (13.6). Significant amounts (≥ 10%) of ≈0.5 MeV photons that may fall into the acceptance window of PET scanners are emitted by 55 Co, 66 Ga, 85m Y, 86 Y, 132 La, and 152 Tb. Compton background from more energetic photons would be expected for 44 Sc, 55 Co, 66 Ga, 86 Y, 90 Nb, 132 La, 150 Tb, and 152 Tb. The mean positron ranges (mm) of 64 Cu (0.6), 85m Y (1.0), 45 Ti (1.5), 133 La (1.6), 43 Sc and 61 Cu (1.7), 55 Co (2.1), 44 Sc and 86 Y (2.5), and 90 Nb (2.6) were lower than that of 68 Ga (3.6). DOTA chelation is applicable for most of the radiometals, though not ideal for 61 Cu/ 64 Cu. Recent data showed that chelation of 45 Ti with DOTA is feasible. 90 Nb requires different complexing agents (e.g., DFO). Finally, they could be economically produced by proton-induced reactions at medical cyclotrons., Conclusion: In particular, 43 Sc, 45 Ti, and 61 Cu have overall excellent β + decay-characteristics for theranostic applications complementing 177 Lu-labelled small conjugates, and they could be sustainably produced. Like Lu, 43 Sc, 45 Ti and to a lesser extent 61 Cu could be labelled with DOTA., Competing Interests: Declarations. Competing interests: The authors have no conflict of interest to disclose, financial or otherwise., (© 2024. The Author(s).)

Purpose: [ 177 Lu]Lu-DOTATATE is an established somatostatin receptor (SSTR) agonist for the treatment of metastasized neuroendocrine neoplasms, while the SSTR antagonist [ 177 Lu]Lu-DOTA-LM3 has only scarcely been employed in clinics. Impressive preclinical data obtained with [ 161 Tb]Tb-DOTA-LM3 in tumor-bearing mice indicated the potential of terbium-161 as an alternative to lutetium-177. The aim of the present study was to compare the tolerability of 161 Tb- and 177 Lu-based DOTA-LM3 and DOTATATE in immunocompetent mice., Methods: Dosimetry calculations were performed based on biodistribution data of the radiopeptides in immunocompetent mice. Treatment-related effects on blood cell counts were assessed on Days 10, 28 and 56 after application of [ 161 Tb]Tb-DOTA-LM3 or [ 161 Tb]Tb-DOTATATE at 20 MBq per mouse. These radiopeptides were also applied at 100 MBq per mouse and the effects compared to those observed after application of the 177 Lu-labeled counterparts. Bone marrow smears, blood plasma parameters and organ histology were assessed at the end of the study., Results: The absorbed organ dose was commonly higher for the SSTR antagonist than for the SSTR agonist and for terbium-161 over lutetium-177. Application of a therapeutic activity level of 20 MBq [ 161 Tb]Tb-DOTA-LM3 or [ 161 Tb]Tb-DOTATATE was well tolerated without major hematological changes. The injection of 100 MBq of the 161 Tb- and 177 Lu-based somatostatin analogues affected the blood cell counts, however. The lymphocytes were 40-50% lower in treated mice compared to the untreated controls on Day 10 irrespective of the radionuclide employed. At the same timepoint, thrombocyte and erythrocyte counts were 30-50% and 6-12% lower, respectively, after administration of the SSTR antagonist (p < 0.05) while changes were less pronounced in mice injected with the SSTR agonist. All blood cell counts were in the normal range on Day 56. Histological analyses revealed minimal abnormalities in the kidneys, liver and spleen of treated mice. No correlation was observed between the organ dose and frequency of the occurrence of abnormalities., Conclusion: Hematologic changes were more pronounced in mice treated with the SSTR antagonist than in those treated with the SSTR agonist. Despite the increased absorbed dose delivered by terbium-161 over lutetium-177, [ 161 Tb]Tb-DOTA-LM3 and [ 161 Tb]Tb-DOTATATE should be safe at activity levels that are recommended for their respective 177 Lu-based analogues., (© 2024. The Author(s).)

The quantum-mechanical nuclear-shell structure determines the stability and limits of the existence of the heaviest nuclides with large proton numbers Z ≳ 100 (refs. 1-3 ). Shell effects also affect the sizes and shapes of atomic nuclei, as shown by laser spectroscopy studies in lighter nuclides 4 . However, experimental information on the charge radii and the nuclear moments of the heavy actinide elements, which link the heaviest naturally abundant nuclides with artificially produced superheavy elements, is sparse 5 . Here we present laser spectroscopy measurements along the fermium (Z = 100) isotopic chain and an extension of data in the nobelium isotopic chain (Z = 102) across a key region. Multiple production schemes and different advanced techniques were applied to determine the isotope shifts in atomic transitions, from which changes in the nuclear mean-square charge radii were extracted. A range of nuclear models based on energy density functionals reproduce well the observed smooth evolution of the nuclear size. Both the remarkable consistency of model prediction and the similarity of predictions for different isotopes suggest a transition to a regime in which shell effects have a diminished effect on the size compared with lighter nuclei., (© 2024. The Author(s).)

Spatiotemporal datasets, which consist of spatially-referenced time series, are ubiquitous in diverse applications, such as air pollution monitoring, disease tracking, and cloud-demand forecasting. As the scale of modern datasets increases, there is a growing need for statistical methods that are flexible enough to capture complex spatiotemporal dynamics and scalable enough to handle many observations. This article introduces the Bayesian Neural Field (BAYESNF), a domain-general statistical model that infers rich spatiotemporal probability distributions for data-analysis tasks including forecasting, interpolation, and variography. BAYESNF integrates a deep neural network architecture for high-capacity function estimation with hierarchical Bayesian inference for robust predictive uncertainty quantification. Evaluations against prominent baselines show that BAYESNF delivers improvements on prediction problems from climate and public health data containing tens to hundreds of thousands of measurements. Accompanying the paper is an open-source software package ( https://github.com/google/bayesnf ) that runs on GPU and TPU accelerators through the JAX machine learning platform., (© 2024. The Author(s).)

Asymptotic giant branch stars are responsible for the production of most of the heavy isotopes beyond Sr observed in the solar system. Among them, isotopes shielded from the r-process contribution by their stable isobars are defined as s-only nuclei. For a long time the abundance of ^{204}Pb, the heaviest s-only isotope, has been a topic of debate because state-of-the-art stellar models appeared to systematically underestimate its solar abundance. Besides the impact of uncertainties from stellar models and galactic chemical evolution simulations, this discrepancy was further obscured by rather divergent theoretical estimates for the neutron capture cross section of its radioactive precursor in the neutron-capture flow, ^{204}Tl (t&#95;{1/2}=3.78  yr), and by the lack of experimental data on this reaction. We present the first ever neutron capture measurement on ^{204}Tl, conducted at the CERN neutron time-of-flight facility n&#95;TOF, employing a sample of only 9 mg of ^{204}Tl produced at the Institute Laue Langevin high flux reactor. By complementing our new results with semiempirical calculations we obtained, at the s-process temperatures of kT≈8  keV and kT≈30  keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new ^{204}Tl MACS, the uncertainty arising from the ^{204}Tl(n,γ) cross section on the s-process abundance of ^{204}Pb has been reduced from ∼30% down to +8%/-6%, and the s-process calculations are in agreement with the latest solar system abundance of ^{204}Pb reported by K. Lodders in 2021.

BOLD-100 (formerly IT-139, KP1339), a well-established chemotherapeutic agent, is currently being investigated in clinical trials for the treatment of gastric, pancreatic, colorectal, and bile duct cancer. Despite numerous studies, the exact mode of action is still the subject of discussions. Radiolabeled BOLD-100 could be a powerful tool to clarify pharmacokinetic pathways of the compound and to predict therapy responses in patients using nuclear molecular imaging prior to the therapy. In this study, the radiosyntheses of carrier-added (c.a.) [ 97/103 Ru]BOLD-100 were performed with the two ruthenium isotopes ruthenium-103 ( 103 Ru; β - , γ) and ruthenium-97 ( 97 Ru; EC, γ), of which in particular the latter isotope is suitable for imaging by single-photon emission computed tomography (SPECT). To identify the best tumor-to-background ratio for diagnostic imaging, biodistribution studies were performed with two different injected doses of c.a. [ 103 Ru]BOLD-100 (3 and 30 mg kg -1 ) in Balb/c mice bearing CT26 allografts over a time period of 72 h. Additionally, ex vivo autoradiography of the tumors (24 h p.i.) was conducted. Our results indicate that the higher injected dose (30 mg kg -1 ) leads to more unspecific accumulation of the compound in non-targeted tissue, which is likely due to an overload of the albumin transport system. It was also shown that lower amounts of injected c.a. [ 103 Ru]BOLD-100 resulted in a relatively higher tumor uptake and, therefore, a better tumor-to-background ratio, which are encouraging results for future imaging studies using c.a. [ 97 Ru]BOLD-100.