Radioactive Half-life Research Articles

An improved semi-empirical relationship for cluster radioactivity * *Supported by the National Natural Science Foundation of China (U1832120, 11675265), the Natural Science Foundation for Outstanding Young Scholars of Hebei Province of China (A2020210012, A2018210146), the Continuous Basic Scientific Research Project (WDJC-2019-13) and the Leading Innovation Project (LC 192209000701)

An improved semi-empirical relationship for cluster radioactivity half-lives is proposed by introducing an accurate charge radius formula and an analytic expression of the preformation probability. Moreover, the cluster radioactivity half-lives for the daughter nuclei around 208Pb or its neighbors and the 12C radioactivity half-life of 114Ba are calculated within the improved semi-empirical relationship. It is shown that the accuracy of the new relationship is improved significantly compared to its predecessor. In addition, the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead and trans-tin nuclei are predicted by the new semi-empirical formula. These predictions might be useful for searching for the new cluster emitters of the two islands in future experiments.

Systematic study of two-proton radioactivity within a Gamow-like model * *Supported in part by the National Natural Science Foundation of China (11205083, 11975132), the Construct Program of the Key Discipline in Hunan Province, the Research Foundation of Education Bureau of Hunan Province, China (18A237), the Natural Science Foundation of Hunan Province, China (2018JJ2321), the Innovation Group of Nuclear and Particle

In this study, based on the Gamow-like model, we systematically analyze two-proton ( ) radioactivity half-lives of nuclei near or beyond the proton drip line. It is found that the calculated results can reproduce experimental data well. Furthermore, using this model, we predict the half-lives of possible radioactivity candidates whose radioactivity is energetically allowed or observed but not yet quantified in the latest table of evaluated nuclear properties, i.e., NUBASE2016. The predicted results are in good agreement with those from other theoretical models and empirical formulas, namely the effective liquid drop model (ELDM), generalized liquid drop model (GLDM), Sreeja formula, and Liu formula.

Demonstration of a Three-Dimensionally Structured Betavoltaic

In this work, we present a demonstration of a high-aspect ratio, three-dimensionally structured betavoltaic device. High-aspect ratio silicon PIN diodes were used as the semiconductor absorber and 147PmCl3 was used as the beta emitter. Three devices were fabricated with 147Pm activities of 2.4 mCi, 7.4 mCi, and 29.5 mCi. The device with the highest activity produced an initial power output of 200 nW and was monitored over a period of 8 months to observe the current–voltage behavior over time, during which time the output current decreased in accordance with the radioactive half-life of 147Pm. Small deviations in the output current of a few percent during the long-term measurement were found to be attributable to the humidity in the room where the experiment was done. The output current generated from the devices was 68–77% of the theoretical maximum, indicating significant infiltration of the radioisotope into the ridged structures.

New Geiger-Nuttall law for two-proton radioactivity * *Supported in part by the National Natural Science Foundation of China (11205083, 11505100, 11705055), the Construct Program of the Key Discipline in Hunan Province, the Research Foundation of Education Bureau of Hunan Province, China (15A159, 18A237), the Natural Science Foundation of Hunan Province, China (2015JJ3103, 2015JJ2121, 2018JJ2321), the Innovation Group of Nuclear and

In the present work, a two-parameter empirical formula is proposed, based on the Geiger-Nuttall law, to study two-proton ( ) radioactivity. Using this formula, the calculated radioactivity half-lives are in good agreement with the experimental data as well as with calculated results obtained by Goncalves et al. [Phys. Lett. B 774, 14 (2017)] using the effective liquid drop model (ELDM), Sreeja et al. [Eur. Phys. J. A 55, 33 (2019)] using a four-parameter empirical formula, and Cui et al. [Phys. Rev. C 101: 014301 (2020)] using a generalized liquid drop model (GLDM). In addition, this two-parameter empirical formula is extended to predict the half-lives of 22 possible radioactivity candidates with radioactivity released energy , obtained from the latest evaluated atomic mass table AME2016. The predicted results are highly consistent with those obtained using other theoretical models such as the ELDM, GLDM and four-parameter empirical formula.

Alpha and heavy cluster radioactivity of superheavy nuclei 100 ⩽ Z ⩽ 120

Using Cubic plus Yukawa plus Exponential (CYE) model, half lives of alpha decay and heavy cluster radioactivity of Superheavy nuclei have been systematically investigated for even-even, even-odd, odd-even and odd-odd nuclei with 100 ⩽ Z ⩽ 120. We have done our calculations by considering the Coulomb, centrifugal and Yukawa plus exponential potentials as an interacting barrier for separated fragments and the cubic potential for the overlapping region.The predicted half life time values by including deformation effects on parent and parent cluster have been compared with theAnalytical Super Asymmetric Fission (ASAF) model of D.N.Poenaru et.al. In this work, we have compared the half life time values of alpha and heavy cluster radioactivity of Super heavy nuclei leading to 208Pb. This study suggests that heavy-cluster radioactivity may be comparable to or even dominant over a decay for some of the isotopes with Z ⩾ 118. Furthermore, branching ratio calculations have been performed to find out the probable cluster emitters. The predictions for cluster emitters are in agreement with CPPM model by Santhosh et. al.,and Wentzel-Kramers-Brillouin (WKB) method by A.Soylu et. al. We hope that this study will help in future measurements on α-decay and cluster radioactivity half-lives of SHN.

Theoretical cluster decay predictions for the nuclei 245−260Md with different nuclear potentials

We have studied systematically the alpha decay and cluster radioactivity half-life of heavy [Formula: see text]Mendelevium ([Formula: see text]) isotopes. The alpha decays from Md isotopes have been studied within the framework of Coulomb and proximity potential model using 14 different versions of nuclear potentials. Also, we have studied the half-lives of alpha decay of Md nuclei within the nuclear potentials generalized liquid drop model (GLDM) and also within GLDM with modified different nuclear potentials, namely proximity potential 2010, 1977, 1988, 2000 and 2002. Moreover, the half-lives of the [Formula: see text]-decay and cluster radioactivity calculated using the Universal formula for cluster decay (UNIV) of Poenaru et al., the Universal decay law (UDL) of Qi et al. and the Unified formula of half-lives for both the [Formula: see text]-decay and cluster radioactivity (UFADCR) of Ni et al. and found to be in good agreement. Our results have been compared with experimental data and demonstrate the acceptability of the approach. Among the different proximity potentials, GLDM with proximity 1977 version (GLDM[Formula: see text][Formula: see text][Formula: see text]P77) ([Formula: see text]) provides the best description for alpha decay studies with low deviation.

Human mass balance, metabolism, and cytochrome P450 phenotyping of lusutrombopag

The human mass balance of lusutrombopag, an orally bioavailable thrombopoietin (TPO) receptor agonist, was characterised in seven healthy male subjects after a single oral dose of [14C]-lusutrombopag (2 mg, 100 μCi) in solution. Lusutrombopag was the main component in plasma, accounting for 56% of plasma radioactivity AUC0-∞. In plasma, the half-life of radioactivity (70.7 h) was longer than that of lusutrombopag (25.7 h), suggesting the presence of long circulating metabolites. The main excretion pathway of lusutorombopag was feces, with a radioactivity recovery of approximately 83% within 336 h post-dose. M6 (lusutrombopag-O-propanol or lusutrombopag-O-acetic acid) and M7 (lusutrombopag-O-ethane-1,2-diol) were also identified as main components in feces, accounting for at most 17.9%, and 16.9% of the dose, respectively, and were β-oxidation related metabolites. Our in vitro metabolism study of lusutrombopag indicated that β-oxidation was a subsequent metabolism of ω-oxidation and CYP4 enzymes, including CYP4A11, were the major isozymes contributing to ω-oxidation. In conclusion, lusutrombopag is primarily eliminated via ω-oxidation and excreted in the feces, where CYP4 enzymes play an important role.

Systematic study of proton radioactivity of spherical proton emitters with Skyrme interactions

Proton radioactivity is an important and common process of the natural radioactivity of proton-rich nuclei. In our previous work [J. H. Cheng et al., Nucl. Rhys. A 997, 121717 (2020)], we systematically studied the proton radioactivity half-lives of 53< Z <83 nuclei within the two-potential approach with Skyrme-Hartree-Fock. The calculations can well reproduce the experimental data of spherical nuclei. The present work is an extension of the previous work. We systematically study 32 proton radioactivity half-lives of spherical nuclei with the two-potential approach with Skyrme-Hartree-Fock (TPA-SHF) within 115 different versions of the Skyrme interactions. The calculated results indicate that the SLy7 Skyrme interaction gives the lowest r.m.s. deviation in the description of the experimental data of the spherical proton emitters among all the different versions of the Skyrme interactions. In addition, we use this model with the SLy7 Skyrme interaction to predict the proton radioactivity half-lives of 7 spherical nuclei in the same region, whose proton radioactivity is energetically allowed or has been observed but is not yet quantified.

Separation and preconcentration of perrhenate from ionic solutions by ion exchange chromatography

Technetium poses an environmental hazard because of its radioactivity and long half-life. It exists in the form of pertechnetate in the environment and can be modeled by the nonradioactive ion perrhenate, since pertechnetate and perrhenate have the same geometry and similar chemical properties. In this research, a new zinc cyclen resorcinarene cavitand (ZCR) column was used in ion chromatography (IC) to efficiently separate perrhenate. Ion chromatography has the advantage of requiring almost no sample preparation for water samples. The ZCR column demonstrated the ability to separate anions: fluoride, chloride, nitrate, sulfate, phosphate, perchlorate, and perrhenate by gradient 2–60 mM NaOH. Unlike other columns, the new column material was selective in retaining perrhenate. The ZCR column also gave a linear range from 2.0 to 1000 mg L−1 for perrhenate with R2 > 0.997. There was a logarithmic relationship between the concentration of perrhenate and its retention time. Excellent perrhenate recovery was achieved on the ZCR column when river water was spiked with perrhenate and perrhenate was preconcentrated. The efficient separations of perrhenate by the ZCR column will potentially assist in pertechnetate separations.

α decay and cluster radioactivity within the redefined preformed cluster method

Half-lives and potential barriers of cluster radioactivity are investigated in the framework of the generalized liquid drop model (GLDM). We focus on the calculation of the preformation factor for heavy and superheavy nuclei within a redefined preformed cluster method, in which the decay constant is the product of the preformation factor, assault frequency, and penetration probability. The preformation factor is obtained from the penetrability of the potential internal barrier. The assault frequency has been estimated using classical methods and the penetration probability is calculated by the Wentzel-Kramers-Brillouin (WKB) method from tunneling through the GLDM potential barrier. The optimal mass inertia was selected for $\ensuremath{\alpha}$ decay and cluster emission by comparison of theoretical half-lives and experimental ones. The calculated preformation factor follows the preformation law formulas $S({A}_{C})=S{(\ensuremath{\alpha})}^{({A}_{C}\ensuremath{-}1)/3}$ [Phys. Rev. Lett. 61, 1930 (1988)], and the theoretical half-lives show better agreement with experimental data, including the new isotopes $^{219}\mathrm{Np}$ [Phys. Lett. B 777, 212 (2018)] and $^{220}\mathrm{Np}$ [Phys. Rev. Lett. 122, 192503 (2019)]. The predictions of cluster radioactivity half-lives are provided for heavy and superheavy nuclei, which will be useful for the detection and identification of these nuclei in the future.

Nucleon density distribution in description of nuclear decays

A correlation is demonstrated between the diffuseness of the self-consistent nucleon distribution and the nucleon-nucleon attraction on nuclear surface. The last two values determine the nucleus-nucleus interaction potential. Because the half-lives of alpha-decay, cluster radioactivity, and spontaneous fission are sensitive to the nucleus-nucleus interaction potential, we try to verify the self-consistent nucleon-nucleon attraction on nuclear surface. Based on the dinuclear system model, the unified approach is proposed for calculating half-lives of different nuclear decay modes using the phenomenological and self-consistent nucleon distributions.

Half-lives of proton emitters studied with the KDE0v1 Skyrme interaction

The half-lives of proton radioactivity of proton emitters are investigated theoretically by using KDE0v1 Skyrme interaction. The total barrier potential in the proton radioactive nuclei is calculated as the sum of the nuclear, Coulomb and centrifugal contributions. The Hartree-Fock nuclear density distributions is used in calculating the nuclear as well as the Coulomb interaction potentials. The quantum mechanical tunneling probability is calculated within the WKB approximation. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes.

Reproduction of sediment deposition and prediction of 137Cs concentration in the major urban rivers of Tokyo

Radioactive caesium- 137 (137Cs) can be used as a tracer to infer sediment dynamics due not only to its long radioactive half-life but also its affinity for fine sediment. A novel advanced interpolation assessment was conducted to examine radionuclide activity in terraced land covered with volcanic ash soil in Tokyo, Japan, which had a time-dependent input function and incorporated the effects of mixed-sediment particle dynamic behaviour on radioactive decay. In addition, transport parameters derived from Chernobyl measurements were applied as predictors of the long-term contamination of the cardinal urban rivers by the fallout from the Tokyo Electric Power Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011. The behaviour of suspended sediment substances, incorporating the effects of deposition and pickup, was assessed using a mixed-sediment particle dynamics model. The concentrations of 137Cs adsorbed on fine sediment particles of each size fraction were determined. Removal of 137Cs from the cardinal urban river channel had significant effects on both long-term decline, including extreme flash flood events, and the dynamic and time-dependent behaviours of interspersed 137Cs and sediment activity. A novel advanced interpolation assessment method was used to examine radionuclide activity in terraced land covered with volcanic ash soil in Tokyo, Japan. The assessment procedure has a time-dependent input function and incorporates the effects of mixed-sediment particle dynamics on this time dependence. The results indicated that sediment and 137Cs concentrations could decline more rapidly than observed in the Fukushima and Chernobyl regions. This rate of decrease depended on terraces covered with volcanic ash soil, which incorporated the effects of fine sediment behaviour for particle adsorption. In addition, comparatively large impacts were observed during extreme flash flooding events, which were associated with the land cover of the major urban river catchments in Tokyo. This work provides a new perspective for understanding 137Cs behaviour associated with reproduction of sediment deposition and prediction of 137Cs concentration in the major urban rivers of Tokyo, incorporating the effects of baseline 137Cs behaviour with the impact of sediment particle adsorption in a volcanic ash soil-covered terrace.

Two-proton radioactivity within a generalized liquid drop model

The generalized liquid drop model (GLDM) is firstly extended to study the two-proton ($2p$) radioactivity half-lives of the ground-state of nuclei. According to the comparison between the calculated half-lives and the experimental data, it is shown that the GLDM describes the $2p$ radioactivity half-lives well. In addition, by comparing its accuracy with other models, it is found that the GLDM has a comparable accuracy with them. Finally, the $2p$ radioactivity half-lives of some most probable candidates are predicted with the GLDM by inputting the \textit{Q}$_{2p}$ values (the released energy of the $2p$ radioactivity) from the updated AME 2016 Mass Table, which may be useful for future experiments.

Method of False Rates for Radioactive Decay Chain Calculation

Many engineering applications involving radioactive materials requires the time history of the radioactivity of nuclides within a decay chain. The system of differential equations with initial conditions or initial value problem describing radioactive decay of a parent and daughter nuclides was posited by Ernest Rutherford who was awarded a Noble Prize in 1910 for this work. Harry Bateman (1910) provided an analytic solution to the radioactive decay chain problem with the constraint that initial inventory of all daughter elements is zero. Required data for the decay chain calculation consists of the parent and all daughters’ radioactive half-life. The half-life for essentially all radionuclides has been established and is available from multiple sources. Solutions other than Bateman’s (non-zero initial conditions) can be computed analytically but become unwieldy for longer decay chains. For this reason, many applications use a numerical solution. However, a numerical solution can require constraints on the time step size. The proposed method of false rates provides a unique algorithm for the decay chain activities. The method treats the decay chain with arbitrary initial conditions and the calculation is analytic or exact. The method is unexpectedly simplistic. An example decay chain calculation compares the solutions by the method of false rates with a numerical method. The comparison is a verification of the method of false rates calculation. The method of false rates is easily coded as a stand-alone application or as a sub-module of a more general code such as a contaminant transport model.

Molecular imaging of advanced atherosclerotic plaques with folate receptor-targeted 2D nanoprobes

Vulnerable atherosclerotic plaques are responsible for most cardiovascular diseases (CVDs). Folate receptor (FR) positive activated macrophages were thought to be a prominent component in the development of vulnerable plaque. The objective of this study is to develop folate conjugated two-dimensional (2D) Pd@Au nanomaterials (Pd@Au-PEG-FA) for targeted multimodal imaging of the FRs in advanced atherosclerotic plaques. Pharmacokinetic and imaging studies (single photon emission computed tomography (SPECT), computed tomography (CT) and photoacoustic (PA) imaging) were performed to confirm the prolonged blood half-life and enrichment of radioactivity in atherosclerotic plaques. Strong signals were detected in vivo with SPECT, CT and PA imaging in heavy atherosclerotic plaques, which were significantly higher than those of the normal aortas after injection of Pd@Au-PEG-FA. Blocking studies with preinjection of excess FA could effectively reduce the targeting ability of Pd@Au-PEG-FA in atherosclerotic plaques, further demonstrating the specific binding of Pd@Au-PEG-FA for plaque lesions. Histopathological characterization revealed that the signal of probe was in accordance with the high-risk plaques. In summary, the Pd@Au-PEG-FA has favorable pharmacokinetic properties and provides a valuable approach for detecting high-risk plaques in the presence of FRs in atherosclerotic plaques.

Transportation behaviour of radioactive substances in soils

In 2011, a number of radioactive substances were released as a result of the accident at the Fukushima Daiichi Nuclear Power Plant, Japan, which was caused by the Tohoku region Pacific coast earthquake. The radioactive substances that were released fell onto the surrounding ground and into the sea. Therefore, decontamination measures for the ground have been conducted at the field site. However, the safety and validity of modern decontamination measures were uncertain because no analytical verification had been performed that considered the various properties of the ground. Moreover, selection of the site where storage containers for radioactive materials could be constructed was a critical issue that required a solution. Therefore, it was necessary to evaluate quantitatively the behaviour of radioactive substances in soils to prepare new decontamination methods for the ground. In this study, the advection–dispersion equation was added to the radioactive half-life to evaluate the transportation of radioactive substances. As the results of this study show, this analytical method could recreate the on-site situation through comparison of the analysis results with the measurement results. Furthermore, modern decontamination techniques were effective for the section under analysis for ground with a silt or a clay layer. However, these techniques were not effective for sand layers.

New Geiger-Nuttall law for proton radioactivity

In the present work considering the contributions of the daughter nuclear charge and the orbital angular momentum taken away by the emitted proton, we propose a two-parameter formula of new Geiger-Nuttall law for proton radioactivity. A set of universal parameters of this law is obtained by fitting 44 experimental data of proton emitters in the ground state and isomeric state. The calculated results can reproduce the experimental data well. For a comparison, the calculations performed using other theoretical methods, such as UDLP proposed by Qi et al. (Phys. Rev. C 85, 011303(R) (2012)), the CPPM-Guo2013 analyzed by our previous work (Deng et al., Eur. Phys. J. A 55, 58 (2019)) and the modified Gamow-like model proposed by us (Chen et al., J. Phys. G: Nucl. Part. Phys. 96, 065107 (2019)) are also included. Meanwhile, we extend this new Geiger-Nuttall law to predict the proton radioactivity half-lives for $ 51 \leq Z \leq 91$ nuclei, whose proton radioactivity is energetically allowed or observed but not yet quantified in NUBASE2016.

Synthesis and in vivo evaluation of [18F]UCB-J for PET imaging of synaptic vesicle glycoprotein 2A (SV2A).

Synaptic abnormalities have been implicated in a variety of neuropsychiatric disorders, including epilepsy, Alzheimer's disease, and schizophrenia. Hence, PET imaging of the synaptic vesicle glycoprotein 2A (SV2A) may be a valuable in vivo biomarker for neurologic and psychiatric diseases. We previously developed [11C]UCB-J, a PET radiotracer with high affinity and selectivity toward SV2A; however, the short radioactive half-life (20min for 11C) places some limitations on its broader application. Herein, we report the first synthesis of the longer-lived 18F-labeled counterpart (half-life: 110min), [18F]UCB-J, and its evaluation in nonhuman primates. [18F]UCB-J was synthesized from the iodonium precursors. PET imaging experiments with [18F]UCB-J were conducted in rhesus monkeys to assess the pharmacokinetic and in vivo binding properties. Arterial samples were taken for analysis of radioactive metabolites and generation of input functions. Regional time-activity curves were analyzed using the one-tissue compartment model to derive regional distribution volumes and binding potentials for comparison with [11C]UCB-J. [18F]UCB-J was prepared in high radiochemical and enantiomeric purity, but low radiochemical yield. Evaluation in nonhuman primates indicated that the radiotracer displayed pharmacokinetic and imaging characteristics similar to those of [11C]UCB-J, with moderate metabolism rate, high brain uptake, fast and reversible binding kinetics, and high specific binding signals. We have accomplished the first synthesis of the novel SV2A radiotracer [18F]UCB-J. [18F]UCB-J is demonstrated to be an excellent imaging agent and may prove to be useful for imaging and quantification of SV2A expression, and synaptic density, in humans.

Half-lives of cluster radioactivity using the modified generalized liquid drop model with a new preformation factor

Half-lives of clusters emitted from radioactive nuclei is determined using modified generalized liquid drop model (MGLDM), where a new preformation factor is added to the existing generalized liquid drop theoretical model with proximity 77 potential. Half-lives for radioactive nuclei whose mass numbers vary from 221 to 242, emitting C, O, F, Ne, Mg, and Si clusters, are calculated theoretically considering deformation and orientation effects and the values are in exact agreement with experimental data. Standard deviation of logarithm of half-lives using present model is found to be 0.755, which is a much better result in comparison with those of GLDM1 and GLDM2 of Bao et al. [J. Phys. G: Nucl. Part. Phys. 39, 095103 (2012)], which are 1.84 and 1.114, respectively. Also, half-lives of various radioactive nuclei whose mass numbers vary from 220 to 250 are predicted. We hope that our present study on cluster half-lives may be helpful for future works in this field.