Nuclear Theory Research Articles

Issues in the Expansion and Contraction of Operators

This paper explores fundamental issues in the correct contraction and expansion of operators, with a primary focus on the concept of symmetry within operator theory. Special attention is given to how symmetry influences the behavior of operators, particularly regarding their approximation and convergence properties. In the domains of quantum mechanics and condensed matter physics, such operators are essential for modeling phenomena like superconductivity, excitons, and surface states. The symmetric properties of operators have a profound impact on the physical interpretations and predictions these models generate. A rigorous analysis is provided regarding the existence of correct contractions and expansions for a specific class of nonlinear operators, demonstrating how symmetry affects the structural integrity of operators under natural conditions. The study presents a comprehensive description of the set of all correct contractions, expansions, and regular expansions, with an application to a third-order nonlinear differential expression. Additionally, a condition for the unique solvability of a Bitsadze–Samarskii-type problem is derived, showcasing how symmetry plays a crucial role in guiding the solution of complex physical models. Furthermore, the paper emphasizes the importance of preserving symmetry in the construction of operators, ensuring the consistency and accuracy of mathematical models. This has significant implications for both theoretical research and practical applications in various fields, including nuclear physics and quantum theory.

Synthesis of Anti-Inflammatory Drugs’ Chalcone Derivatives and a Study of Their Conformational Properties Through a Combination of Nuclear Magnetic Resonance Spectroscopy and Molecular Modeling

Background: In this study, two chalcone analogs were synthesized through in silico and experimental methods, and their potential to inhibit the lipoxygenase enzyme, which plays a role in the inflammation pathway, was assessed. Specifically, this study is a continuation of previous research in which chalcone derivatives were synthesized and characterized. Objectives/Methods: In the current work, we present the re-synthesis of two chalcones, with a focus on their docking studies, NMR analysis, and dynamic simulations. The structure of each chalcone was elucidated through a combination of Nuclear Magnetic Resonance (NMR) and Density Functional Theory (DFT). The substituent effect on the absorption spectrum of the two chalcone derivatives was studied. Results: A “LOX–chalcone” complex, predicted by docking studies, was further examined using molecular dynamics (MD) simulations to evaluate the stability of the complex. After fully characterizing the “LOX–chalcone” complexes in silico, the atomic details of each chalcone’s interaction with LOX-1 and 5-LOX were revealed through Saturation Transfer Difference (STD) NMR (Nuclear Magnetic Resonance). Finally, their selectivity profile was investigated against human 15-LOX-1 and general Lipoxidase activity. Conclusions: The in silico methods suggest that chalcones could be promising lead compounds for drug designs targeting the LOX enzyme.

Ultrastable and ultra-accurate clock transitions in open-shell highly charged ions

Highly charged ions (HCIs) are less sensitive to external perturbations and are therefore attractive for the development of ultrastable clocks. However, only a few HCI candidates are known to provide optical clock transitions. In this work, we discover a large family of HCI clocks, with more than 100 suitable optical clock transitions hidden in the fine-structure terms of open-shell ions over 70 elements. Their projected instabilities and accuracies are στ~10−17/τ and δν/ν < 10−20, respectively, surpassing state-of-the-art optical clocks by several orders of magnitude. This indicates that having a high-performance optical clock transition is not a property of particular elements, but a virtue host by most elements from the periodic table. Furthermore, at given configurations, the clock transitions in heavy ions scale up to the XUV and soft-x-ray region, and thus enable the development of ultrastable clocks based on shorter wavelengths. The existence of multiple clock transitions in different charge states of a single element, as well as in a whole isoelectronic sequence would significantly enrich the search for new physics and the test of nuclear theories via high-precision spectroscopy.

Unveiling Active Al3+ Sites for Ethanol Dehydration on γ-Al2O3 with Solid-State Nuclear Magnetic Resonance Spectroscopy.

γ-Al2O3 is a crucial catalyst widely used in industrial alcohol dehydration processes. However, the specific nature of its active sites has remained unclear. In this study, we utilize two-dimensional heteronuclear correlation solid-state nuclear magnetic resonance and density functional theory calculations to uncover the active Al sites on the surface of γ-Al2O3 that facilitate ethanol dehydration. We show the formation of stable pentacoordinated AlV-ethanol complexes upon the adsorption of ethanol on the tetracoordinated AlIV sites. This interaction significantly enhances synergy with adjacent AlV-OH sites, resulting in a marked reduction of the activation energy barrier for ethene production. Furthermore, we reveal an interchange between AlIV and AlV-OH species, allowing hexacoordinated AlVI-OH sites to participate in the dehydration pathway through the migration of ethanol between these coordination sites.

Investigating a Seemingly Simple Imine-Linked Covalent Organic Framework Structure.

The structures of covalent organic frameworks (COFs) are typically determined through modeling based on powder X-ray diffraction. However, the intrinsically limited crystallinity of COFs often results in structural determinations of low fidelity. Here, we present real-space imaging of an extensively studied two-dimensional imine-based COF. Contrary to the conventional understanding that this COF features uniform hexagonal pores, our observations reveal the presence of two distinct sets of pores with differences in shape and size. Motivated by this finding, we conducted reciprocal-space characterizations, complemented by solid-state nuclear magnetic resonance spectroscopy and density functional theory calculations, to reevaluate this seemingly simple structure. The collective results allow for the establishment of a new structural model for this landmark COF and its derivatives, differing from the conventional model in both intra- and interlayer configurations. Furthermore, we identified various previously unrecognized defective structures through real-space imaging, which have significant implications for COF applications in separation and catalysis. Our study demonstrates the complexity and heterogeneity of COF structures, while also highlighting the imperative for structural reevaluation using advanced characterization techniques.

Bidimensional Gegenbauer Polynomials for Variable‐Order Time‐Fractional Integro‐Partial Differential Equation With a Weakly Singular Kernel

ABSTRACTIn this paper, a pseudo‐operational collocation method based on Gegenbauer polynomials is presented to solve a category of variable‐order time‐fractional integro‐partial differential equations with singular kernels. The applications of these functional equations can be revealed in the theory of elasticity, hydrodynamics, heat conduction, and nuclear reactor theory. The pseudo‐operational matrices are constructed utilizing bivariate Gegenbauer polynomials to approximate the solution of the mentioned equation. Then, using the collocation method and resultant matrices, the main equation is converted into a system of algebraic equations that can be solved by Newton's iteration method. Besides presenting a fast and accurate method, an error bound is determined in a Gegenbauer‐weighted space for the residual function obtained from the proposed approach. Finally, several test examples are performed to confirm the reliability and efficiency of the proposed method.

Sequential Pore Functionalization in MOFs for Enhanced Carbon Dioxide Capture.

The capture of carbon dioxide (CO2) is crucial for reducing greenhouse emissions and achieving net-zero emission goals. Metal-organic frameworks (MOFs) present a promising solution for carbon capture due to their structural adaptability, tunability, porosity, and pore modification. In this research, we explored the use of a copper (Cu(II))-based MOF called m CBMOF-1. After activation, m CBMOF-1 generates one-dimensional channels with square cross sections, featuring sets of four Cu(II) open metal sites spaced by 6.042 Å, allowing strong interactions with coordinating molecules. To investigate this capability, m CBMOF-1 was exposed to ammonia (NH3) gas, resulting in hysteretic NH3 isotherms indicative of strong interactions between Cu(II) and NH3. At 150 mbar and 298 K, the NH3-loaded (∼1 mmol/g) material exhibited a 106% increase in CO2 uptake compared to that of the pristine m CBMOF-1. Carbon-13 solid-state nuclear magnetic resonance spectra and density functional theory calculations confirmed that the sequential loading of NH3 followed by CO2 adsorption generated a copper-carbamic acid complex within the pores of m CBMOF-1. Our study highlights the effectiveness of sequential pore functionalization in MOFs as an attractive strategy for enhancing the interactions of MOFs with small molecules such as CO2.

Asymptotic normalization coefficients for α+C12 synthesis and the S factor for C12(α,γ)O16 radiative capture

: The C12(α,γ)O16 reaction, determining the survival of carbon in red giants, is of interest for nuclear reaction theory and nuclear astrophysics. A specific feature of the O16 nuclear structure is the presence of two subthreshold bound states, (6.92 MeV, 2+) and (7.12 MeV, 1−), that dominate the behavior of the low-energy S factor. The strength of these subthreshold states is determined by their asymptotic normalization coefficients (ANCs), which need to be known with high accuracy. : The objective of this research is to examine how the subthreshold and ground-state ANCs impact the low-energy S factor, especially at the key astrophysical energy of 300keV. The S factors are calculated within the framework of the R-matrix method using the code. Our total S factor takes into account the E1 and E2 transitions to the ground state of O16 including the interference of the subthreshold and higher resonances, which also interfere with the corresponding direct captures, and cascade radiative captures to the ground state of O16 through four subthreshold states: 02+,3−,2+, and 1−. To evaluate the impact of subthreshold ANCs on the low-energy S factor, we employ two sets of the ANCs. The first selection, which offers higher ANC values, is attained through the extrapolation process [Blokhintsev , ]. The set with low ANC values was employed by deBoer []. A detailed comparison of the S factors at the most effective astrophysical energy of 300 keV is provided, along with an investigation into how the ground-state ANC affects this S factor. : The contribution to the total E1 and E2S factors from the corresponding subthreshold resonances at 300keV are (71–74)% and (102–103)%, respectively. The correlation of the uncertainties of the subthreshold ANCs with the E1 and E2S(300keV) factors is found. The E1 transition of the subthreshold resonance 1− does not depend on the ground-state ANC but interferes constructively with a broad (9.585MeV;1−) resonance giving (for the present subthreshold ANC) an additional 26% contribution to the total E1S(300keV) factor. Interference of the E2 transition through the subthreshold resonance 2+ with direct capture is almost negligible for small ground-state ANC of 58fm−1/2. However, its interference with direct capture for higher ground-state ANC of 337fm−1/2 is significant and destructive, contributing −27%. The low-energy SE2(300keV) factor experiences a smaller increase when both subthfreshold and the ground-state ANCs rise together due to their anticorrelation, compared to when only the subthreshold ANCs increase.Published by the American Physical Society2024

Dracarys: Unleashing the Lessons of Nuclear Conflict from House of the Dragon

Given increasing nuclear-related dangers in the real world, which pose an existential threat to humanity, teaching nuclear theory to students is critically important. I argue that the hit TV show House of the Dragon can be utilized to educate students on the nuances of nuclear theory in a fun and engaging—but also surprisingly rigorous—way. In particular, the fire-breathing weapons of mass destruction in the Game of Thrones prequel show illustrate five key lessons about nuclear conflict dynamics. First, nuclear war is incredibly destructive and causes significant psychological trauma to survivors of nuclear attacks. Second, nuclear weapons can induce caution in leaders and deter major war. Third, while a powerful force, nuclear deterrence can fail due to irrational leaders, principle-agent problems, and accidents. Fourth, nuclear compellence is harder than nuclear deterrence and can backfire. Fifth, nuclear superiority beyond a secure second-strike capability provides little strategic benefit. In sum, House of the Dragon offers a more modern option than classics like Dr. Strangelove to teach about nuclear theory.

Nuclear Magnetic Resonance (NMR) and Density Functional Theory (DFT) Study of Water Clusters of Hydrogen-Rich Water (HRW)

The present study investigated the 1H Nuclear Magnetic Resonance (NMR) spectra of hydrogen-rich water (HRW) produced using the EVObooster device. The analyzed HRW has pH = 7.1 ± 0.11, oxidation–reduction potential (ORP) of (−450 ± 11) mV, and a dissolved hydrogen concentration of 1.2 ppm. The control sample was tap water filtered by patented technology. A 600 NMR spectrometer was used to measure NMR spectra. Isotropic 1H nuclear magnetic shielding constants of the most stable clusters (H2O)n with n from 3 to 28 have been calculated by employing the gauge-including-atomic-orbital (GIAO) method at the MPW1PW91/6-311+G(2d,p) density function level of theory (DFT). The HRW chemical shift is downfield (higher chemical shifts) due to increased hydrogen bonding. More extensive formations were formed in HRW than in control filtered tap water. The exchange of protons between water molecules is rapid in HRW, and the 1H NMR spectra are in fast exchange mode. Therefore, we averaged the calculated chemical shifts of the investigated water clusters. As the size of the clusters increases, the number of hydrogen bonds increases, which leads to an increase in the chemical shift. The dependence is an exponential saturation that occurs at about N = 10. The modeled clusters in HRW are structurally stabilized, suggesting well-ordered hydrogen bonds. In the article, different processes are described for the transport of water molecules and clusters. These processes are with aquaporins, fusion pores, gap-junction channels, and WAT FOUR model. The exponential trend of saturation shows the dynamics of water molecules in clusters. In our research, the chemical shift of 4.257 ppm indicates stable water clusters of 4–5 water molecules. The pentagonal rings in dodecahedron cage H3O+(H2O)20 allow for an optimal arrangement of hydrogen bonds that minimizes the potential energy.

Highly selective and sensitive N-amidothiourea-based fluorescence chemosensor for detecting Zn2+ ions and cell Imaging: Potential applications for plasma membrane detection

A “turn-on” fluorescent sensor L was developed for the selective detection of Zn2+ ions in biological settings. This sensor exhibited a specific response to Zn2+ ions, with a detection limit of 39 nM. Analyses through titration and Job’s plot confirmed that the formed complex has a 2:1 stoichiometry (L: Zn2+). The sensor displayed strong selectivity for Zn2+ over other metal ions, demonstrating a robust binding affinity while effectively reducing interference from heavy metals. The identification process was validated by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR) titrations, mass spectrometry (MS), and Density Functional Theory (DFT) calculations. Maximum fluorescence intensity was achieved upon interaction with Zn2+ ions within a physiological pH range of 7.0–7.5. Moreover, successful imaging experiments in HEK293 cells highlighted the sensor’s potential as a powerful tool for monitoring interactions at the plasma membrane.

Stereoselective synthesis of geminal bromofluoroalkenes by kinetically controlled selective conversion of oxaphosphetane intermediates.

Geminal bromofluoroalkenes are an important subclass of versatile organic interhalide, which can serve as useful synthetic precursors to monofluoroalkenes that are valuable amide group isosteres. Nonetheless, despite the vast advancement of olefination methodologies, the broadly applicable stereoselective synthesis remained elusive for geminal bromofluoroalkenes before our work. In particular, the seemingly straightforward Wittig-type approach with interhalogenated phosphorus ylide has been unsuccessful because of the difficulty in the diastereoselective oxaphosphetane formation. Here, we describe a conceptually distinctive strategy, by which the stereoselectivity is gained via the selective decomposition of the oxaphosphetane intermediates. The suitably identified phosphorus(III) reagent and reaction medium enabled efficient kinetic differentiation, which was supported by nuclear magnetic resonance analysis and density functional theory calculation. Through our method, the highly diastereoselective synthesis of geminal E-bromofluoroalkenes was accomplished in one step. Furthermore, the generality was demonstrated by accommodating a wide range of readily available carbonyl compounds, including ketones and pharmaceutical substrates.

Robustness of the $N=152$ and $Z=108$ shell closures in superheavy mass region

Abstract The neutron shell gap at $N=152$ has been experimentally confirmed through high-precision mass measurements on nobelium ($Z=102$) and lawrencium ($Z=103$) isotopes. The experimental measurements on $\alpha$-decay properties suggest the deformed doubly-magic nature of $^{270}$Hs. However, the magic gaps in the superheavy region are generally expected to be fragile. In this study, we test the robustness of the $N=152$ shell closure in $N=152$ isotones and $Z=108$ shell closure in Hs isotopes by employing an alternative approach where both theoretical analysis and available experimental data are required. Combined with existing experimental measurements on $\alpha$-decay energies, it is found that the robust $N=152$ neutron shell persists at least in&amp;#xD;$Z=101-105$ isotopes, and the robust $Z=108$ proton shell persists in Hs isotopes with $N=159, 160$. These results provide crucial benchmarks for constraining effective interactions suitable for superheavy nuclei in nuclear energy-density functional theory.

Towards hypernuclei from nuclear lattice effective field theory

Understanding the strong interactions within baryonic systems beyond the up and down quark sector is pivotal for a comprehensive description of nuclear forces. This study explores the interactions involving hyperons, particularly the Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varLambda $$\\end{document} particle, within the framework of nuclear lattice effective field theory (NLEFT). By incorporating Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varLambda $$\\end{document} hyperons into the NLEFT framework, we extend our investigation into the S=-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S = -1$$\\end{document} sector, allowing us to probe the third dimension of the nuclear chart. We calculate the Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varLambda $$\\end{document} separation energies (BΛ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_{\\varLambda }$$\\end{document}) of hypernuclei up to the medium-mass region, providing valuable insights into hyperon–nucleon (YN) and hyperon–nucleon–nucleon (YNN) interactions. Our calculations employ high-fidelity chiral interactions at N3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ ^3$$\\end{document}LO for nucleons and extend it to Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varLambda $$\\end{document} hyperons with leading-order S-wave YN interactions as well as YNN forces constrained only by the A=4,5\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$A=4,5$$\\end{document} systems. Our results contribute to a deeper understanding of the SU(3) symmetry breaking and establish a foundation for future improvements in hypernuclear calculations.

The triton lifetime from nuclear lattice effective field theory

In this work, we present a calculation of the triton β-decay lifetime using Nuclear Lattice Effective Field Theory (NLEFT) at next-to-next-to-next-to-leading order in the chiral expansion. By incorporating a non-perturbative treatment of the higher-order corrections, we achieve consistent predictions for the Fermi and Gamow-Teller matrix elements, which are crucial for determining the triton lifetime. Our results are consistent with earlier theoretical calculations, confirming the robustness of our approach. This study marks a significant advancement in the systematic application of NLEFT to nuclear β-decay processes, paving the way for future high-precision calculations in more complex nuclear systems. Additionally, we discuss potential improvements to our approach, including the explicit inclusion of two-pion exchange mechanisms and the refinement of three-nucleon forces. These developments are essential for extending the applicability of NLEFT to a broader range of nuclear phenomena, including neutrinoless double-β decay.

Resource Letter: Synthesis of the elements in stars

This Resource Letter provides a guide to the literature on the field of nuclear astrophysics, and particularly the origin of the elements. Nuclear astrophysics is a multidisciplinary field that aims at understanding where everything we see around us comes from and how it came to be. Astronomical observations, astrophysics modeling, and nuclear physics experiment and theory come together to answer important questions like: Where and how are the elements created? How do stars evolve? What drives the different types of stellar explosions? What is left behind after the cataclysmic death of a star? This Resource Letter presents our current understanding of the origin of the various chemical elements, together with modern research and new developments in the field, with a particular focus on the measurement of nuclear properties for astrophysical applications.

Synthesis and characterization of a chiral spirobifluorene cyclic hexamer

Abstract A new chiral macrocycle 1-[6], consisting of six chiral spirobifluorene units linked in a cyclic arrangement, was successfully synthesized via a homo-coupling of the corresponding acyclic trimer. Notably, this chiral cyclic hexamer exhibited flexibility in solution, and both low-temperature nuclear magnetic resonance (NMR) experiments and density functional theory (DFT) calculations suggest that its stable structure is not the hexagonal D6-symmetric structure but rather the figure-eight-shaped D2-symmetric structure. In this D2-symmetric structure, the opposing bifluorenyl units are π-stacked, and it is suggested that this π-stacked region undergoes rapid dissociation and reformation at room temperature. The HOMO is distributed over the π-stacked region, with a HOMO-LUMO gap of 4.02 eV. The macrocycle exhibited strong violet fluorescence. The absorption dissymmetry factor |gabs| was 7.4 × 10−3, which is larger compared to the series of chiral smaller macrocycles 1-[n] (n = 3 to 5). Additionally, the CPL efficiency, indicated by a BCPL value of 189 M−1 cm−1, is relatively high among chiral organic luminescent molecules.

Simultaneous Measurement of the Half-Life and Spectral Shape of ^{115}In β Decay with an Indium Iodide Cryogenic Calorimeter.

Current bounds on the neutrino Majorana mass are affected by significant uncertainties in the nuclear calculations for neutrinoless double-beta decay. A key issue for a data-driven improvement of the nuclear theory is the actual value of the axial coupling constant g_{A}, which can be investigated through forbidden β decays. We present the first measurement of the 4th-forbidden β decay of ^{115}In with a cryogenic calorimeter based on indium iodide. Exploiting the enhanced spectrum-shape method for the first time to this isotope, our study accurately determines simultaneously spectral shape, g_{A}, and half-life. The interacting shell model, which best fits our data, indicates a half-life for this decay at T_{1/2}=(5.26±0.06)×10^{14} yr.

Extended Fayans energy density functional: optimization and analysis

The Fayans energy density functional (EDF) has been very successful in describing global nuclear properties (binding energies, charge radii, and especially differences of radii) within nuclear density functional theory. In a recent study, supervised machine learning methods were used to calibrate the Fayans EDF. Building on this experience, in this work we explore the effect of adding isovector pairing terms, which are responsible for different proton and neutron pairing fields, by comparing a 13D model without the isovector pairing term against the extended 14D model. At the heart of the calibration is a carefully selected heterogeneous dataset of experimental observables representing ground-state properties of spherical even–even nuclei. To quantify the impact of the calibration dataset on model parameters and the importance of the new terms, we carry out advanced sensitivity and correlation analysis on both models. The extension to 14D improves the overall quality of the model by about 30%. The enhanced degrees of freedom of the 14D model reduce correlations between model parameters and enhance sensitivity.

Quasi-particle–vibration coupling approach for nuclear β-decay

The study of β-decay is important to answer open questions in physics and astrophysics; however, theoretical predictions of the associated half-lives are still plagued by uncertainties. In this short review, we argue that a reliable model for this study is nuclear density functional theory (DFT), complemented by further specific correlations; the quasi-particle–vibration coupling (QPVC) model has been successful in predicting half-lives in a number of spherical nuclei, and its extension to deformed systems should be envisioned. Some remaining open questions are addressed.