Nuclear Transition Research Articles

Optimising control over nuclear spin transitions

Optimising control over nuclear spin transitions

Probing the hierarchical dynamics of DNA-sperm nuclear transition protein complexes through fuzzy interaction and mesoscale condensation.

Nuclear transition protein TNP1 is a crucial player mediating histone-protamine exchange in condensing spermatids. A unique combination of intrinsic disorder and multivalent properties turns TNP1 into an ideal agent for orchestrating the formation of versatile TNP-DNA assemblies. Despite its significance, the physicochemical property and the molecular mechanism followed by TNP1 for histone replacement and DNA condensation are still poorly understood. This study reports the first-time in vitro expression and purification of human TNP1 and investigates the hierarchical dynamics of TNP1-DNA interaction using a combination of computational simulations, biochemical assays, fluorescence imaging, and atomic force microscopy. We explored three crucial facets of TNP1-DNA interactions. Initially, we delve into the molecular binding process that entails fuzzy interactions between TNP1 and DNA at the atomistic scale. Subsequently, we analyze how TNP1 binding affects the electrostatic and mechanical characteristics of DNA and influences its morphology. Finally, we study the biomolecular condensation of TNP1-DNA when subjected to high concentrations. The findings of our study set the foundation for comprehending the potential involvement of TNP1 in histone replacement and DNA condensation in spermatogenesis.

Re-Approaching EU’s Energy Policy: The Vital Role of Nuclear Power

The energy cut-down that followed the Russo-Ukrainian war is the main cause of the recent skyrocketing gas prices, which are jeopardizing the stability of the EU’s internal energy market. Hence, the diversification of energy sources has become a major priority. In this context, nuclear power must be reconsidered as a reliable alternative energy source which can lead to the partial independence of the EU. The upper goal of energy security can only be achieved if the EU relies on an energy source, such as nuclear, that ensures availability, reliability, affordability, and sustainability – all, at once. This policy brief outlines the importance of nuclear energy as a key factor for the EU’s energy future and proposes measures that can be implemented to achieve a nuclear and green transition.

Effects of Electrons on Nuclear Clock Transition Frequency in ^{229}Th Ions.

We perform calculations of the energy shift of the nuclear clock transition frequency ^{229}Th as a function of the number of electrons in Th ion. We demonstrate that the dependence of the nuclear frequency on electron configuration is significant, for example, removing one electron from the atom leads to relative shift of the nuclear frequency ∼10^{-7}, which is 12 orders of magnitude larger than the expected relative uncertainty of the nuclear clock transition frequency (∼10^{-19}). This leads to the difference of the nuclear clock frequencies in Th IV, Th III, Th II, and Th I. The relative change of the nuclear frequency between neutral Th and its bare nucleus is 1%. We also calculate the field shift constants for isotopic and isomeric shifts of atomic electron transitions in Th ions.

Construction mechanism of gellan gum/chitosan/calcium ion multiple‐network hydrogel by self‐assembly strategy and its regulation

AbstractRecently, double‐network or multiple‐network hydrogel constructed by physical methods has been considered a green method to improve the comprehensive properties of biomass hydrogel. Herein, a novel physically cross‐linked hydrogel with multiple network of gellan gum/chitosan/calcium ion (GG–CS–Ca) was constructed by self‐assembly to accomplish the synergistic improvement of mechanical strength and uranium adsorption property compared to adsorbents GG–Ca and carboxymethyl konjac glucomannan/GG–Al originated from gellan gum previously prepared. Moreover, the driving mechanism of self‐assembly of GG–CS–Ca was deduced by 13C solid state nuclear magnetic resonance spectroscopy (13C‐SSNMR), rheological analysis, and phase transition analysis. The results indicated electrostatic interaction was dominant during the self‐assembly of GG–CS–Ca. The self‐assembly mechanism was also illustrated by investigating the x‐ray photoelectron spectrometer (XPS) combined with the analysis of the phase transition process. Comprehensively, the self‐assembly constructed GG–CS–Ca hydrogel network contained three kinds of network including the GG–CS network constructed by electrostatic action of protonated CS with negative charged GG, the GG–Ca network constructed by ionic cross‐linking of COO− in GG and Ca2+, and the GG network formed after the phase transformation of GG hot sol by cooling. It explored a new method for constructing biomass‐based physical hydrogels with both favorable mechanical strength and uranium adsorption capacity in uranium removal.Highlights A novel physically cross‐linked hydrogel (GG–CS–Ca) with multiple network was constructed by self‐assembly. The GG–CS–Ca hydrogel accomplished the synergistic improvement of mechanical strength and uranium adsorption properties. The self‐assembly mechanism of constructing the GG–CS–Ca hydrogel network contained three aspects. The electrostatic interaction was the dominant action during the self‐assembly of GG–CS–Ca.

Fundamental Accuracy-Resolution Trade-Off for Timekeeping Devices.

From a thermodynamic point of view, all clocks are driven by irreversible processes. Additionally, one can use oscillatory systems to temporally modulate the thermodynamic flux towards equilibrium. Focusing on the most elementary thermalization events, this modulation can be thought of as a temporal probability concentration for these events. There are two fundamental factors limiting the performance of clocks: On the one level, the inevitable drifts of the oscillatory system, which are addressed by finding stable atomic or nuclear transitions that lead to astounding precision of today's clocks. On the other level, there is the intrinsically stochastic nature of the irreversible events upon which the clock's operation is based. This becomes relevant when seeking to maximize a clock's resolution at high accuracy, which is ultimately limited by the number of such stochastic events per reference time unit. We address this essential trade-off between clock accuracy and resolution, proving a universal bound for all clocks whose elementary thermalization events are memoryless.

Constraints on NJL four-fermion effective interactions from neutrinoless double beta decay

We study the contribution of a heavy right-handed Majorana neutrino to neutrinoless double beta decay (0νββ) via four-fermion effective interactions of Nambu-Jona-Lasinio (NJL) type. In this physical scenario, the sterile neutrino contributes to the nuclear transition through gauge, contact, and mixed interactions. Using the lower limit on the half-life of 0νββ from the KamLAND-Zen experiment, we then constrain the effective right-handed coupling between the sterile neutrino and the W boson: GRW\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{G}}_R^W $$\\end{document}. Eventually, we show that the obtained bounds are compatible with those found in the literature, which highlights the complementarity of this type of phenomenological study with high-energy experiments.

Odd-even shape staggering and kink structure of charge radii of Hg isotopes by the deformed relativistic Hartree–Bogoliubov theory in continuum

We examined the shape staggering of relative charge radii in 180−186Hg isotopes, which was first measured in 1977 and recently confirmed using advanced spectroscopy techniques. To understand the nuclear structure underlying this phenomenon, we employed the deformed relativistic Hartree–Bogoliubov theory in continuum (DRHBc). Our analysis revealed that the shape staggering can be attributed to nuclear shape transition in the Hg isotopes. Specifically, we demonstrated that prolate shapes of 181,183,185Hg lead to an increase in the charge radii compared to oblate shapes of 180,182,184,186Hg isotopes. We explained the nuclear shape staggering in terms of the evolution of occupation probability (OP) of ν1i13/2, ν1h9/2, π1h9/2, and π3s1/2 states. Additionally, we clarified the kink structure of the charge radii in the Hg isotopes near N=126 magic shell does not come from the change of the OP of π1h9/2 state, but mainly by the increase of the OPs of ν1i11/2 and ν2g9/2 states.

Racialization and International Security

Abstract Racialization—the processes that infuse social and political phenomena with racial identities and implications—is an assertion of power, a claim of purportedly inherent differences that has saturated modern diplomacy, order, and violence. Despite the field's consistent interest in power, international security studies in the United States largely omitted racial dynamics from decades of debates about international conflict and cooperation, nuclear proliferation, power transitions, unipolarity, civil wars, terrorism, international order, grand strategy, and other subjects. A new framework lays conceptual bedrock, links relevant literatures to major research agendas in international security, cultivates interdisciplinary dialogues, and charts promising paths to consider how overt and embedded racialization shape the study and practice of international security. A discussion of several research design challenges for integrating racialization into existing and new research agendas helps scholars reconsider how they approach questions of race and security. Beyond diversifying the professoriat itself, revealing and countering embedded biases are crucial to determine how alternative ideas have been marginalized, and, ultimately, to develop better theories.

Resonant X-ray excitation of the nuclear clock isomer 45Sc

Resonant oscillators with stable frequencies and large quality factors help us to keep track of time with high precision. Examples range from quartz crystal oscillators in wristwatches to atomic oscillators in atomic clocks, which are, at present, our most precise time measurement devices1. The search for more stable and convenient reference oscillators is continuing2–6. Nuclear oscillators are better than atomic oscillators because of their naturally higher quality factors and higher resilience against external perturbations7–9. One of the most promising cases is an ultra-narrow nuclear resonance transition in 45Sc between the ground state and the 12.4-keV isomeric state with a long lifetime of 0.47 s (ref. 10). The scientific potential of 45Sc was realized long ago, but applications require 45Sc resonant excitation, which in turn requires accelerator-driven, high-brightness X-ray sources11 that have become available only recently. Here we report on resonant X-ray excitation of the 45Sc isomeric state by irradiation of Sc-metal foil with 12.4-keV photon pulses from a state-of-the-art X-ray free-electron laser and subsequent detection of nuclear decay products. Simultaneously, the transition energy was determined as {mathrm{12,389.59}}_{+0.12left({rm{syst}}right)}^{pm 0.15left({rm{stat}}right)},{rm{eV}} with an uncertainty that is two orders of magnitude smaller than the previously known values. These advancements enable the application of this isomer in extreme metrology, nuclear clock technology, ultra-high-precision spectroscopy and similar applications.

Nuclear Shape-Phase Transition From Spherical U(5) to Deformed gamma-Unstable O(6) Dynamical Symmetries of Interacting Boson Model Applied to Ru, Pd, and Xe Isotopic Chains

The shape transition from spherical vibrator U(5) to gamma-unstable deformed rotor O(6) in even-even Ru, Pd, and Xe isotopic chains are studied in framework of sd interacting boson model (IBM1) using the coherent state formalism to obtain the potential energy surfaces (PES’s). The location of critical points in the transition are identified by analysis the PES’s in terms of the deformation parameter beta and by using the catastrophe theory in terms of the two essential parameters (r_1, r_2). By using the most general IBM1 Hamiltonian in Casimir form with neglecting the U(5) and SU(3) quadratic Casimir operators and introducing only one control parameter the PES leads to the same energy surface as the Q-consistent IBM Hamiltonian at gamma =0. For the studied isotopic chains, the chi ^2-test is used to perform the fitting between the experimental and the corresponding calculated IBM for some selected energy levels and electric quadrupole transition probabilities B(E2) values using a simulated search program. A good agreement is produced for both energies and B(E2) transition rates. The present model calculations suggest that ^{100}Ru, ^{102}Pd and ^{130}Xe nuclei are good candidates for the E(5) critical point symmetry.

Temozolomide-based sonodynamic therapy induces immunogenic cell death in glioma

BackgroundIn our previous study, we found for the first time that temozolomide (TMZ), the first-line chemotherapeutic agent for glioblastoma (GBM), can generate a large amount of reactive oxygen species (ROS) under ultrasound irradiation. Sonodynamic therapy (SDT) using TMZ as the sonosensitizer produced more potent antitumor effects than TMZ alone. Here, we further evaluate the effects of TMZ-based SDT on subcellular structures and investigate the immunogenic cell death (ICD)-inducing capability of TMZ-based SDT. MethodsThe sonotoxic effects of TMZ were explored in LN229 and GL261 glioma cells. The morphology of endoplasmic reticulum and mitochondria was observed by transmission electron microscopy. The nuclear DNA damage was represented by γ-H2AX staining. Bone marrow-derived dendritic cells (BMDCs) were employed to assess ICD-inducing capability of TMZ-based SDT. A cyclic arginine-glycine-aspartic (c(RGDyC))-modified nanoliposome drug delivery platform was used to improve the tumor targeting of SDT. ResultsTMZ-based SDT had a greater inhibitory effect on glioma cells than TMZ alone. Transmission electron microscopy revealed that TMZ-based SDT caused endoplasmic reticulum dilation and mitochondrial swelling. In addition, endoplasmic reticulum stress response (ERSR), nuclear DNA damage and mitochondrial permeability transition pore (mPTP) opening were promoted in TMZ-based SDT group. Most importantly, we found that TMZ-based SDT could promote the “danger signals” produced by glioma cells and induce the maturation and activation of BMDCs, which was associated with the mitochondrial DNA released into the cytoplasm in glioma cells. In vivo experiments showed that TMZ-based SDT could remodel glioma immune microenvironment and provoke durable and powerful anti-tumor immune responses. What's more, the engineered nanoliposome vector of TMZ conferred SDT tumor targeting, providing an option for safer clinical application of TMZ in combination with SDT in the future. ConclusionsTMZ-based SDT was capable of triggering ICD in glioma. The discovery of TMZ as a sonosensitizer have shown great promise in the treatment of GBM.

Probing the Dark Sector with Nuclear Transition Photons.

Here we present world-leading sensitivity to light (<170 MeV) dark matter (DM) using beam-dump experiments. Dark sector particles produced during pion decay at accelerator beam dumps can be detected via scattering in neutrino detectors. The decay of nuclei excited by the inelastic scattering of DM is an unexploited channel which has significantly better sensitivity than similar searches using the elastic scattering channel. We show that this channel is a powerful probe of DM by demonstrating sensitivity to the thermal relic abundance benchmark in a scalar DM dark-photon portal model. This is achieved through the use of existing data, obtained by the KARMEN experiment over two decades ago, which allow us to set world-leading constraints on this model over a wide mass range. With experimental improvements planned for the future, this technique will be able to probe the thermal relic benchmark for fermionic DM across a wide mass range.

Laser Plasma‐Accelerated Ultra‐Intense Electron Beam for Efficiently Exciting Nuclear Isomers

AbstractUtilizing a laser plasma wakefield to accelerate ultrahigh charge and current electron beams is critical for many pioneering applications, for example, to efficiently produce nuclear isomers with short lifetimes that may be widely used. However, because of the beam loading effect, the electron charge in a single plasma bubble is limited to hundreds of picocoulombs. Herein, via a tightly focused intense laser pulse self‐guiding in dense gas, a twenty‐nanocoulomb, tens‐of‐MeV, hundred‐kiloampere collimated electron beam is produced from a chain of plasma bubbles in the saturated injection regime. This intense electron beam is utilized to excite indium nuclear isomers with an ultrahigh peak rate of particles·s‐1 via photonuclear reaction. This efficient isomer production method can be widely used for pumping isotopes with excited state lifetimes on the picosecond scale, which is beneficial for deeply understanding nuclear transition mechanisms or stimulating γ‐ray lasers.

Effect of initial-state geometric configurations on the nuclear liquid-gas phase transition

Effect of initial-state geometric configurations on the nuclear liquid-gas phase transition

Virtual Nukes: The Formulation of Japan’s Non-nuclear Weapons Security Policy

Informed by newly-declassified U.S. and Japanese documents, this study explains how Japan made the strategic choice to maintain its status as a non-nuclear weapons state, made possible by external and internal arrangements devised between 1964-1976. Japan obtained official and private security assurances from the U.S. ensuring its nuclear protection, preserved its material capabilities that could allow for an independent nuclear weaponization in emergencies, and simultaneously constructed public narratives that were politically justifiable to international and domestic audiences. U.S.-Japan public statements (such as Joint Communiques) and secret agreements (regarding U.S. nuclear transit rights in Japan and U.S. emergency re-entry rights in Okinawa) mutually reinforced each other, preserving U.S. deterrent capabilities in East Asia. Dual security assurances, in effect, enabled Japan to refrain from pursuing its own nuclear path. Essentially, secrecy characterized the origins of Japan’s non-nuclear weapons security policy, formulated prior to its entry into the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) framework.

Nuclear Shape Transition, Triaxiality and Energy Staggering of $$\Upsilon$$-Band States for Even–Even Xenon Isotopic Chain

Nuclear Shape Transition, Triaxiality and Energy Staggering of $$\Upsilon$$-Band States for Even–Even Xenon Isotopic Chain

ISAI: Investigating Solar Axion by Iron-57

The existence of the axion is a unique solution for the strong CP problem, and the axion is one of the most promising candidates of the dark matter. Investigating Solar Axion by Iron-57 (ISAI) is being prepared as a complemented table-top experiment to confirm the solar axion scenario. Probing an X-ray emission from the nuclear transitions associated with the axion-nucleon coupling is a leading approach. ISAI searches for the monochromatic 14.4 keV X-ray from the first excited state of ^{57}57Fe using a state-of-the-art pixelized silicon detector, dubbed XRPIX, under an extremely low-background environment. We highlight scientific objectives, experimental design and the latest status of ISAI.

Probing DDM and ML quantum concepts in shape phase transitions of γ-unstable nuclei

In a recent paper (S. Ait El Korchi et al. (2020) [32]), we explored, inside the context of Critical Point Symmetries (CPSs) X(3) and Z(4), a correlation between two exceedingly known quantum concepts, the Minimal Length (ML) and the Deformation-Dependent Mass (DDM), that are commonly applied in various areas of physics. Such a correlation has been strongly identified in transition nuclei by calculating some physical observables of that quantum system, like as energy spectra, moments of inertia and transition probabilities. In this paper we extend that study to E(5) dynamical symmetry corresponding to the shape phase transition U(5)↔O(6). The experimental realization of the models was found to occur in some nuclei, using the existing phenomenological potentials: Infinite Square Well, Davidson and Kratzer, whose models fits provide the best agreement. Importantly the calculations performed in this work using these potentials, corroborate the fact that the revealed correlation between both quantum concepts is not destructively affected by the presence of other model's parameters and hence its existence is independent of the form or type of the used potential. Undoubtedly, the present work will open the way for more investigations of this correlation in the limits of other critical points symmetries in nuclear shape phase transitions which play today a major role in nuclear structure research from theoretical as well as experimental point of view.

Cobalt application in repair tools for maintenance and modernisation of NPP equipment

Relevance. The research discusses the actual risks that can arise from the formation of the radioisotope cobalt 60Co from the stable isotope 59Co during radiation neutron capture, which is specific to repair work at a nuclear power plant, but these risks are poorly understood. Aim. The research aims to analyse the possibility of additional exposure to ionising radiation for the repair personnel of a nuclear power plant due to the use of a repair tool that may contain cobalt. Methodology. The physical-theoretical and analytical approaches are used in the study. Results. A certain risk has been identified as a result of the use of drills or other tools for cutting metal containing cobalt among the repair tools. The calculation (analysis) of the activation of a cobalt-containing drill bit showed that a drill bit weighing 500 g containing 8% of 59Co in the tool steel acquires a partial activity (i.e., only cobalt activity) of 5.397 × 10-8 Ci, which leads to gamma radiation with an exposure dose rate of 0.024 mSv/year. The calculations of dose rates did not consider gamma radiation from the nuclear isomeric transition 60mCo→60Co, which could only worsen the radiation risk picture (when considering other examples). Conclusions. The use of a drill bit with the cobalt content specified in the calculations (or the location of the drill bit in the vicinity of the personnel), one way or another, contributes to the personnel exposure. It is proved that the calculation was not conservative, but rather liberal, because gamma radiation from the 60mCo isomer was not considered, otherwise, the obtained numerical values would have been higher. A practical recommendation to prohibit or reduce the use of tools containing cobalt during repairs on nuclear power plant equipment was made, theoretically, given that the analytically justified need to study the issue of radiation safety is relevant and vital for the safety of NPP maintenance personnel