Decay Chain Research Articles

Study of lepton flavor universality and angular distributions in D→KJ∗(→Kπ)ℓνℓ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D\\rightarrow K^*_{J} (\\rightarrow K\\pi )\\ell \ u _{\\ell }$$\\end{document}

The decay of the D meson into multibody final states is a complex process that provides valuable insights into the fundamental interactions within the Standard Model of particle physics. This study focuses on the decay cascade D+→KJ∗ℓ+ν→K±π∓ℓ+ν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D^{+}\\rightarrow K^{*}_{J} \\ell ^{+}\ u \\rightarrow K^{\\pm }\\pi ^{\\mp } \\ell ^{+}\ u $$\\end{document} where the KJ∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^*_J$$\\end{document} resonance encompasses the K∗(892),K∗(1410),K0∗(1430)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^*(892),K^{*}(1410),K^{*}_0(1430)$$\\end{document} states. We employ the helicity amplitude technique to derive the angular distributions for the decay chain, enabling the extraction of one-dimensional and two-dimensional distributions. Utilizing form factors for the D→K∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D\\rightarrow K^*$$\\end{document} transition derived from the quark model, we calculate the differential and integrated partial decay widths, explicitly considering the electron and muon masses. Decay branching fractions are calculated, the ratios of the branching fractions are found to be Br(D+→K∗(892)(→K-π+)μ+νμ)Br(D+→K∗(892)(→K-π+)e+νe)=0.975\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{\\mathcal {B}r(D^{+}\\rightarrow K^{*}(892)(\\rightarrow K ^{-}\\pi ^{+}) \\, \\mu ^{+}\ u _{\\mu })}{\\mathcal {B}r(D^{+}\\rightarrow K^{*}(892)(\\rightarrow K ^{-}\\pi ^{+}) \\, e^{+}\ u _{e})} = 0.975$$\\end{document}, Br(D+→K∗(1410)(→K-π+)μ+νμ)Br(D+→K∗(1410)(→K-π+)e+νe)=0.714\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{\\mathcal {B}r(D^{+}\\rightarrow K^{*}(1410)(\\rightarrow K ^{-}\\pi ^{+}) \\, \\mu ^{+}\ u _{\\mu })}{\\mathcal {B}r(D^{+}\\rightarrow K^{*}(1410)(\\rightarrow K ^{-}\\pi ^{+}) \\, e^{+}\ u _{e})} = 0.714$$\\end{document} and Br(D+→K0∗(1430)(→K+π-)μ+νμ)Br(D+→K0∗(1430)(→K+π-)e+νe)=0.774\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{\\mathcal {B}r(D^{+}\\rightarrow K^{*}_{0}(1430)(\\rightarrow K ^{+}\\pi ^{-}) \\, \\mu ^{+}\ u _{\\mu })}{\\mathcal {B}r(D^{+}\\rightarrow K^{*}_{0}(1430)(\\rightarrow K ^{+}\\pi ^{-}) \\, e^{+}\ u _{e})} = 0.774$$\\end{document}. Results in this work will serve a calibration for the study of c→s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$c \\rightarrow s $$\\end{document} in D meson decays in future and provide useful information towards the understanding of the properties of the K∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^{*}$$\\end{document} meson, as well as Kπ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K \\pi $$\\end{document} system.

Analysis of the multi-term fractional Bateman equations in radioactive decay by means of Mikusiński algebraic calculus

Fractional Bateman equations model the concentrations of nuclear species through a radioactive decay chain, by considering non-Markovian behavior. Cruz-López and Espinosa-Paredes (Nuclear Engineering and Technology, 2022) solved the mathematical problem with a single memory coefficient, based on the Laplace-transform technique. Cruz-López, Espinosa-Paredes and François (Computer Physics Communications, 2022) extended the analysis to several fractional orders, with Laplace transforms and series expansions checked by induction. In this paper, we solve such a case of distinct memory effects, via the more general method of Mikusiński operational calculus. We do not distinguish between equal and different decay rates. Multivariate Mittag-Leffler functions appear in the closed-form expression.

Double-mixing CP violation in B decays

AbstractWe study a long-overlooked CP violation observable, termed double-mixing CP violation, which arises from the interference between two neutral meson oscillating paths involved in a decay chain. The double-mixing CP violation is beneficial for the precise test of the Standard Model CKM mechanism, as it offers the potential to extract weak phases without pollution from strong dynamics. To provide a comprehensive understanding of the double-mixing CP violation, we perform phenomenological analyses on the cascade decays of the $$B^0_d$$ B d 0 and $$B^0_s$$ B s 0 mesons. Our results show that the double-mixing CP violation can be very significant in certain decay channels, such as $$B^0_d \rightarrow J/\psi K \rightarrow J/\psi (\pi ^+\ell ^-{\bar{\nu }}_\ell )$$ B d 0 → J / ψ K → J / ψ ( π + ℓ - ν ¯ ℓ ) , where the total CP violation arises almost entirely from the double-mixing CP violation. In addition, we employ the decay process $$B^0_d \rightarrow D^0 K \rightarrow (K^-\pi ^+)(\pi \ell \nu )$$ B d 0 → D 0 K → ( K - π + ) ( π ℓ ν ) to demonstrate that the involved strong and weak phases can be directly determined from the experimental data without any theoretical inputs. Specifically, the overall weak phase of this process is $$2\beta +\gamma $$ 2 β + γ , which is of significant importance for extracting the CKM phase angles. We also use $$B^0_s \rightarrow \rho ^0 K \rightarrow \rho ^0(\pi ^-\ell ^+\nu _\ell )$$ B s 0 → ρ 0 K → ρ 0 ( π - ℓ + ν ℓ ) to illustrate and discuss the significant importance of $$K^0_S - K^0_L$$ K S 0 - K L 0 interference.

A Comprehensive Review of Diffusing Alpha-Emitters Radiation Therapy (DaRT): From Dosimetry to Its Biological Effectiveness

Diffusing alpha-emitters radiation therapy (DaRT) represents a groundbreaking development in cancer therapy, offering a solution to the limitations of conventional radiation therapy. By deploying <sup>224</sup>Ra embedded seeds, DaRT achieves targeted delivery of high-dose alpha particles directly to tumor sites, showing considerable efficacy in tumor control and minimal damage to adjacent healthy tissues. This comprehensive review analyzes the published literature regarding mechanisms, seed production, dose calculation, measurement, and biological experiments related to DaRT. It includes in-depth discussions on mathematical models, Monte Carlo simulations for dose distribution, real-time <i>in vivo</i> dosimetry developments, and biological experiments both in vitro and <i>in vivo</i>. Clinical trial outcomes are also examined to evaluate the therapy’s effectiveness in various cancer types. DaRT utilizes <sup>224</sup>Ra-labeled seeds, using the decay chain of <sup>224</sup>Ra to deliver alpha particles effectively within a tumor. Several asymptotic diffusion-leakage models were developed to calculate the alpha dose distribution of DaRT. <i>In vivo</i> dosimetry techniques have been developed for real-time monitoring. Biological experiments demonstrated the cytotoxic effects of DaRT across various cancer cells, with varying radiosensitivity. Additionally, the enhanced effects of combined therapy with chemotherapy and immunotherapy were suggested by many <i>in vivo</i> studies. Clinical trials have shown high complete response rate in squamous cell carcinoma, with minimal side effects, suggesting DaRT’s feasibility and safety. DaRT emerges as a highly localized cancer treatment method with minimal side effects compared to traditional radiation therapy. It directly ablates tumors and potentially enhances immune responses, indicating a significant advance in cancer therapy. Future research and ongoing clinical trials will further elucidate its efficacy across different cancer types and in combination with other treatments.

Calibration of an ionisation chamber for parent-progeny decay

Abstract For a single radionuclide being measured in an ionisation chamber, a calibration factor can be established that relates the ionisation current to the source activity. The same applies to a decay chain in secular equilibrium, for which the calibration factor comprises the ionisation current produced by the parent and progeny nuclei combined. The calibration of an ionisation chamber for non-equilibrated parent-progeny decay poses a problem, since the activity ratio of parent and progeny nuclei varies with time. This paper examines cases in which the half-lives of the parent and only one of the progeny in the decay series are significantly long. Thus, two calibration factors are involved which combine differently as a function of time. By means of nuclear dating of the material, the parent-progeny activity ratio can be determined and the respective contributions to the ionisation current unambiguously distinguished. Once the ionisation chamber is calibrated, two measurements taken at different times are sufficient to determine the activity and age of a parent-progeny mixture. This study presents equations for calculating the calibration factors and propagating uncertainties, illustrated with a case study focussing on the 227Th-223Ra decay chain used in alpha-immunotherapy.

Force Decay Behavior of Orthodontic Elastomeric Chains in Simulated Oral Conditions.

Background Elastomeric chains are widely used for incisor retraction and space closure. However, the force they exert diminishes over time, and this makes it difficult to determine the actual force transmitted to the dentition. The force decay may also be affected by exposure to saliva, foods, beverages, and prophylactic agents. Objective To assess the force degradation of four commercially available orthodontic elastomeric chains (AlastiK, 3M; Generation II Power Chain, Ormco; Elastic Chain, Morelli; and Plastic Chain, American Orthodontics) over 28 days in simulated oral conditions using tooth movement and a prophylactic fluoride rinse regimen. Method A total of 80 chain samples, with 20 samples of each chain type having four loops each, were stretched to 25 mm on custom-fabricated acrylic resin jigs with provision for a space closure mechanism. The samples were divided equally into two groups: a control group, in which ten samples of each chain type were maintained in artificial saliva at 37°C, and a test group, in which ten samples of each chain type were maintained in artificial saliva at 37°C and additionally subjected to simulated tooth movement with jig closure of 0.25 mm/week and a twice-daily regimen of prophylactic fluoride rinse. Force decay was measured using a digital force gauge at the time of engagement on the jigs, at one hour, four hours, and at one, seven, 14, 21, and 28 days. Percentage force decay was calculated, and the results were subjected to one-way analysis of variance (ANOVA), post-hoc Tukey, post-hoc Bonferroni, and 't' test. Results Maximum force degradation was observed at one day for all four chain materials in both groups, followed by a steady force loss over 28 days, the difference being significant for all materials at various time intervals (p<0.05). No significant difference was observed between any material at any given time in the control group (p>0.05); however, significant differences were observed in the test group. Under simulated oral conditions, force decay was maximum for the Plastic Chain, American Orthodontics (67.9 ± 6.24%), and minimum for the Generation II Power Chain, Ormco (51.9 ± 9.78%) at the end of the test period. Conclusion Plastic Chain, American Orthodontics, and AlastiK, 3M chain, exhibited higher force decay when compared to Generation II Power Chain, Ormco, and Elastic Chain, Morelli. Simulated oral conditions significantly affected the force decay of elastomeric chains, and it may be desirable to change elastomeric chains at 14 days for optimum retraction force.

INTDOSKIT: An R-Code for Calculation of Dose Coefficients and Studying Their Uncertainties.

An R-code, which allows the calculation of the time dependent activity distribution based on ICRP reference models, the number of decays in a commitment period, and the dose coefficients for tissues and organs of the human body, has been developed. R Language was chosen due to its powerful mathematical and statistical modeling features, as well as its graphical capabilities. The developed set of functions and constants (called "INTDOSKIT") can be sourced in R-scripts that define or import the models and calculations to be performed. The code has been tested on models of several radionuclides and was successfully validated against reference data taken from ICRP OIR Data Viewer software. Furthermore, the code has been tested and verified on the modeling of the radioactivity of decay chains using data of the 233Ra model presented by Höllriegl and colleagues. The results of calculations with INTDOSKIT demonstrated that the code is able to reproduce the ICRP bioassay data and dose coefficients. Deviations are a few percent only and are due mainly to rounding in the original data. Lastly, the code is able to handle uncertainty and sensitivity studies as demonstrated by the results in a pilot study of injection of 241Am, which estimated geometric standard deviations (GSD) for dose coefficients ranging between 1.25 (bone-surface) and 1.66 (testes); these results are consistent with those obtained from similar studies done by other researchers who reported GSD values ranging from 1.13 to 1.73.

Characterisation of radioactive decay series by digital autoradiography, part 1: A theoretical approach using time and space coincidence (TSC) analysis

The three natural decay chains have short-lived daughter elements, and the existence of these radioelements makes it possible for alpha and beta particle emissions to be generated at the same place and the same time. We show theoretically that such time and space coincidences (TSCs) can be detected efficiently by suitable autoradiographic systems using an algorithm that is six times more efficient than an approach based on the classical slicing of space-time. Two types of TSC coexist: true TSCs, resulting from the decay of short-lived daughter elements, and random TSCs. True TSCs are predictable and their numbers vary linearly with activity; the prediction of true α/α and α/α/α TSCs of the 235U chain is presented. Random coincidences are also predictable using Poisson's law. They vary quadratically as a function of activity. Examination of the case of an uranium ore at secular equilibrium shows that the observed α/α coincidences result from the sum of random and true TSCs. For high uranium contents, random coincidences predominate. For uranium at secular equilibrium, the theoretical calculation shows that true TSCs predominate for contents below ∼5000 ppm.

The Effects of Activated Carbon Toothpastes on Orthodontic Elastomeric Chains—An In Vitro Study

Objectives: Using toothpaste with activated carbon might increase the decay of orthodontic elastomeric chains’ (ECs) tensile strength, thereby compromising orthodontic treatment. Therefore, this study aimed to evaluate the influence of activated charcoal toothpaste on orthodontic ECs. Materials and Methods: A total sample of 180 EC segments from 3M Unitek®, Ormco® and Ortho Classic® brands were equally divided into 12 groups, each comprising 15 specimens. These pieces were kept in artificial saliva at 37 °C and brushed twice daily for 28 days, with three distinct types of toothpaste: Colgate® Total, Colgate® Max White, and Dr Organic® Extra Whitening Charcoal Toothpaste. The latter two toothpastes contain activated charcoal. Tensile strength, resistance to rupture and colour variation were evaluated at time zero and day 28. Descriptive statistics, one-way ANOVA and Tukey HSD tests were performed at p ≤ 0.05. Results: Toothpaste with and without activated carbon significantly reduced the tensile strength and resistance to rupture of the ECs, and altered EC colour (p &lt; 0.0001). There was inconsistency in the effect of the activated carbon on EC characteristics, most probably due to the different compositions of the ECs and percentages of whitening agents in the toothpastes. Conclusions: The material composition of ECs contributes to their tensile strength decay, resistance to rupture and colour change over time. The variable percentage of activated carbon in a toothpaste likely underlies the different effects observed, depending on the EC brand. Clinical Relevance: It might be reasonable to advise patients wearing ECs to avoid using toothpaste with activated carbon until further evidence becomes available.

Assessing Radiation Fallout in Public Zones near the Nevada National Security Site (NNSS): A Recent Study.

A comprehensive radiological study was conducted in the surrounding public zones of the Nevada National Security Site to identify traces of resuspended radioactivity and heavy elemental contamination that might have resulted from various activities. The study used passive and active nuclear methods, specifically gamma spectrometry and instrumental neutron activation analysis, respectively. Passive gamma spectra analysis of air filter papers from various Community Environmental Monitoring Program stations conclusively verified the presence of radionuclides exclusively originating from the natural decay series of 238U and 232Th. Furthermore, gamma spectrometry and instrumental neutron activation analysis of plant samples from surrounding areas of the Nevada National Security Site revealed the absence of any unusual elemental contamination in the environment. These results demonstrated that there was no measurable radiological impact on the public zones surrounding the site resulting from the spread of radioactive materials or toxic heavy metals associated with previous or ongoing activities at Nevada National Security Site. Therefore, the safety of public zones concerning retained radioactivity and harmful elemental contamination arising from Nevada National Security Site operations is negligible. The significance of this study is further pronounced in the current geopolitical context, as it establishes the baseline elemental composition for various desert plants for future reference.

CP violation induced by neutral meson mixing interference

We investigate a long-overlooked CP violation effect—the double-mixing CP asymmetry—in a type of cascade decay that involves at least two mixing neutral mesons in the decay chain. It is induced by the interference between different oscillation paths of the neutral mesons in the decay process. The double-mixing CP asymmetry is of critical importance for phenomenology, providing opportunities for clean determination of Cabibbo-Kobayashi-Maskawa phase angles free of uncertainties induced by the strong dynamics. To illustrate this point, we perform a phenomenological analysis on two examples: Bs0→ρ0K→ρ0(π−ℓ+νℓ) and B0→D0K→D0(π+ℓ−ν¯ℓ). Our results demonstrate that the double-mixing CP asymmetry can be numerically significant in the absence of strong phases, as shown by the former example. Additionally, the latter example showcases a direct extraction of weak and strong phases from data, without the need for theoretical inputs. Published by the American Physical Society 2024

Determine the concentration of radon and uranium in different types of tea

ABSTRACT Radon is a radioactive element from 238U decay series which is naturally occurring and found in different concentrations in many biological formations. This radioactive gas rises from the sample and enters the homes and human lungs daily. The present study aims to determine the concentration of radon in 25 different types of tea collected from local markets in Kurdistan Iraqi region which are mostly consumed by the population because tea is one of the most food used in the form of cold and hot drinks in Iraq, so 25 samples of the most frequently traded tea have been collected from the market. Analysis of the concentrations of Radon-222 and Radium-226 for different types of household tea samples are very substantial for realising the comparative contributes of specific substances to the whole radon content set within the human body and his environment, which is the recommended limit for ICRP values (200–800) Bq.m−3. CR-39 detector was used to record the tracks of alpha particles released from radon content within the tea samples with PVC tube. The chemical etching NaOH solution 6.25 N was using at 70°C for 8 hours to enlarge and appear the alpha tracks, then scanned by microscope. The results showed that the lowest concentration of radon was 3.468 Bq.m−3 (TE11, 0.01%) found in Aero plane tea, while the highest value was recorded in Royal tea which was 123.467 Bq.m-3 (TE22, 8%) with an average value of radon concentration was 61.754 Bq.m−3. The obtained radon concentration levels in the samples were lower than the global permissibility limiting of exposure to radon were within the allowed limit value (200 Bq.m−3), also found to be lower than the (400 Bq.m−3) according to ICRP in foods; therefore, this will not form any risk on human being life.

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.

Circular Economy Principles in the Regulatory Oversight of the Management of By- Products – Case Study: Tin Slag 2

The tin processing industry generates abundant slag, as a by-product, that contains radioactive substances from uranium and thorium decay series radionuclides. The increase in tin production will be proportional to the rise in tin slag. The Circular economy is a concept that aims to minimize the extraction of primary resources, keep resources as long as possible, increase added value, or limit the final disposal of waste. The concept of reuse, recycling, or reprocessing is part of the concept. This paper aims to identify aspects of the existing regulations in Indonesia that support circular economy principles in the management of by-products, such as tin slag 2. The methodology used in this paper is a literature study of regulations, international recommendations, and related research. Based on the measurements of tin slag 2 samples originating from Bangka Belitung Province, the main chemical constituents based on XRF analysis are SiO2, CaO, MgO, Fe2O3, and TiO2. The activity concentration of a tin slag 2 sample showed a value that exceeded the criterion of 1 Bq/gram for the radionuclides in the uranium and thorium decay series. From a material perspective, tin slag 2 can be reused or recycled for specific purposes. Various studies have proven the performance of tin slag 2 as a partial substitution of fine aggregate or cement in manufacturing mortar or concrete. The identification shows that several existing regulations in Indonesia explicitly and implicitly regulate the provisions of the circular economy concept. According to the Ministry of Environment and Forestry regulations, by-products with activity concentrations of less than 1 Bq/gram can be used as raw material, raw material substitution, energy source substitution, and other uses. Meanwhile, the by-products with activity concentrations of more than 1 Bq/gram are challenging as the provisions of by-products with a value of more than 1 Bq/gram are regulated in BAPETEN Regulation No. 16 of 2013 (currently in the revision stage). BAPETEN Regulation No. 16 of 2013 explains that by-products can be utilized for certain activities. However, the regulation must explain the terms and criteria for reusing by-products. Provisions of by-product processing, as stipulated in GR No. 52 of 2022, are limited to extracting nuclear minerals such as uranium and thorium. So, the meaning of processing in GR No. 52 of 2022 and provisions for reuse previously contained in BAPETEN Regulation No. 16 of 2013 have different meanings. Keywords: circular economy, by-product, tin, slag 2, radioactive substances, nuclear minerals

Recursive analytical solution for nonequilibrium multispecies transport of decaying contaminant simultaneously coupled in both the dissolved and sorbed phases

Multispecies transport analytical models that solve advection-dispersion equations (ADEs) are efficient tools for evaluating the transport of decaying contaminants and their sequential products. This study develops a novel semi-analytical model to simulate the multispecies transport of decaying contaminants, considering nonequilibrium sorption and decay in both dissolved and sorbed phases. First-order reversible kinetic sorption equations with decay processes are coupled to ADEs. Recursive analytical solutions, using the Laplace transform and generalized integral transform, are developed to address the mathematical complexity of the governing equations. The model's simulation results show excellent agreement with both numerical models and existing analytical solutions. Applied to a four-member radionuclide decay chain, the model reveals that including decay in the sorbed phase results in a lower concentration of the first member and avoids underestimating the radioactivity concentrations of daughter elements. These differences in dissolved radioactivity concentrations between models with and without sorbed phase decay may impact health risk assessments for radioactive waste disposal. Finally, this study provides a more sophisticated mathematical tool for analyzing multispecies transport in real field conditions where nonequilibrium sorption processes predominantly occur.

Ternary fission of various Z=120 isotopes with 3H, 4He and 8Be as light charge particle

The spontaneous cold ternary fission of various Z = 120 isotopes accompanied by light charge particles (LCP's)3H, 4He and 8Be in equatorial configuration is investigated using Unified ternary fission model (UTFM). The favourable ternary fission channel is predicted based on the computation of Q value, driving potential, barrier penetrability and relative yield of all potential ternary fragment configurations. For the parent isotopes 302,306,308,120 with LCP 3H, the maximum relative yield is for the combinations that have one fragment respectively as 131,132I and 139Ba, which are nearly magic. However, in the case of310120 with LCP 3H, the combination 145La+162Sm+3H exhibits the maximum relative yield. For the 4He accompanied fission of 302,306,308,310,120 isotopes, the fragmentation that include 139Cs, 140,144Ba and 131Te isotopes, which is in the vicinity of shell closure possess high relative yield. In the case of8Be accompanied ternary breakup of the parent isotopes 302,306,120, the maximum yield is due to the magic neutron shell and near-magic proton shell of 134Te. Whereas, for parent isotopes 308,310,120, it is due to the presence of respective doubly magic 132Sn and near doubly magic 131Sn as one fragment. Therefore, our findings emphasize the prominent role of both high Q value as well as existence of doubly and near doubly magic nuclei in the ternary fission of super heavy even-even isotopes 302,306–310,120, accompanied by light charge particles 3H, 4He and 8Be.

A baseline of natural radionuclides in water and sediment of a pristine coastal ecosystem: The Xcalak and Mahahual coral reef lagoons in the western Caribbean

In ecosystems, natural radionuclides are present in the environment and living organisms. The 238U natural decay chain produces multiple radioactive elements, such as 234U, 226Ra, 210Pb, and 210Po. These radionuclides can be found in air, water, rocks, soil, and other biotic and abiotic components, mainly derived from minerals, such as zircon and apatite. In this study, we determined the activity concentration of radionuclides from the 238U decay chain in the sediment of a coastal ecosystem on the southern Mexican coast in the western Caribbean, an ecosystem minimally affected by industrial activities. Methods included high-resolution gamma-ray spectrometry and alpha-particle spectrometry. Results showed that the sediment samples had an activity concentration range of 18.2–36.6 Bq/kg for 238U, 25.0–41.4 Bq/kg for 234U, 10.1–37.3 Bq/kg for 210Pb, and 29.9–46.0 Bq/kg for 210Po. Water samples ranged between 17.9 and 36.3 mBq/L and 27.9–66.0 mBq/L for 238U and 234U, respectively. The activity concentration of these radionuclides in the sediment and water of this area is compared with that of other coral reefs worldwide, providing a radiometric baseline for comparison purposes.

Efficacy of zeolites in radon adsorption: state of the art and development of an optimized approach

ABSTRACT Radon is a radioactive noble gas omnipresent in the environment, being part of the 238U and 232Th decay chains present in the Earth's crust. The gas can easily leak through the ground but also be present in natural construction materials and migrate into indoor places where it can be a carcinogen when inhaled. Studying the content and removal of indoor radon is crucial for the evaluation and mitigation of its radiological risks to public health. For more than 100 years, the removal by adsorption of the radon has been performed on activated charcoal. There is little progress in the field of radon adsorption at ambient conditions; the main progress is in the use of zeolite materials, having well-defined three-dimensional porous structures and radiation resistance. This study concerns a report on the state of the art of the application of zeolites in radon adsorption. Furthermore, an optimized approach for measuring the radon content in indoor environments and, consequently, its removal has been proposed. Adsorption systems based on zeolites have the potential to replace activated charcoal as a material of choice, allowing to facilitate the development of simple and compact radon adsorption systems.

SUPHRE: A Reactive Transport Model With Unsaturated and Density‐Dependent Flow

AbstractAlthough unsaturated and density‐dependent flow affect solute fate in groundwater, they are rarely both included in reactive transport models. Using the operator‐splitting method, a new reactive transport model (SUPHRE) was developed by combining a variable‐saturation and variable‐density multiple‐component solute transport model (SUTRA‐MS) with a geochemical reaction module (PhreeqcRM). In contrast to existing reactive transport models, SUPHRE accounts for both unsaturated and density‐dependent flow. Model setup for SUPHRE is convenient, as only one setup file is required in addition to the usual input files of SUTRA‐MS and PhreeqcRM. By further implementing a time‐variant boundary condition into SUTRA‐MS, SUPHRE can simulate multi‐component reactive transport in tidally influenced coastal unconfined aquifers where unsaturated and density‐dependent flow prevail. Two examples were used to validate the new reactive transport model, including single‐species decay and sorption within a one‐dimensional soil column and a four‐species decay chain in a two‐dimensional aquifer. Following validation, SUPHRE was adopted to reveal unsaturated flow effects on oxygen consumption and nitrate reduction in tidally influenced coastal unconfined aquifers. Whether for simulating oxygen consumption or nitrate reduction, there were visible deviations between numerical results without and with unsaturated flow, highlighting that unsaturated flow can affect reactive solute transport and transformation.

Changes in the Force Decay of Orthodontic Elastomeric Chains after Immersion in Different Mouthrinses

Changes in the Force Decay of Orthodontic Elastomeric Chains after Immersion in Different Mouthrinses