Nuclear Transition Research Articles

The oncogenic transcription factor FUS-CHOP can undergo nuclear liquid-liquid phase separation.

Myxoid liposarcoma is caused by a chromosomal translocation resulting in a fusion protein comprised of the N terminus of FUS (fused in sarcoma) and the full-length transcription factor CHOP (CCAAT/enhancer-binding protein homologous protein, also known as DDIT3). FUS functions in RNA metabolism, and CHOP is a stress-induced transcription factor. The FUS-CHOP fusion protein causes unique gene expression and oncogenic transformation. Although it is clear that the FUS segment is required for oncogenic transformation, the mechanism of FUS-CHOP-induced transcriptional activation is unknown. Recently, some transcription factors and super enhancers have been proposed to undergo liquid-liquid phase separation and form membraneless compartments that recruit transcription machinery to gene promoters. Since phase separation of FUS depends on its N terminus, transcriptional activation by FUS-CHOP could result from the N terminus driving nuclear phase transitions. Here, we characterized FUS-CHOP in cells and in vitro, and observed novel phase-separating properties relative to unmodified CHOP. Our data indicate that FUS-CHOP forms phase-separated condensates that colocalize with BRD4, a marker of super enhancer condensates. We provide evidence that the FUS-CHOP phase transition is a novel oncogenic mechanism and potential therapeutic target for myxoid liposarcoma. This article has an associated First Person interview with the first author of the paper.

Nuclear Shape Phase Transitions Using IBM Applied to Erbium and Ruthenium Nuclei

Nuclear Shape Phase Transitions Using IBM Applied to Erbium and Ruthenium Nuclei

The first experimental evidence for the (M1 + E2) mixed character of the 9.2 keV transition in 227Th

The 9.2 keV nuclear transition in 227Th was studied in the β−-decay of 227Ac by means of the internal conversion electron spectroscopy to clarify the spin-parity assignment of the ground state and the two lowest excited states of 227Th. The transition multipolarity was proved to be of mixed character M1 + E2 and the spectroscopic admixture parameter δ2(E2/M1)=0.695±0.248 (|δ(E2/M1)|=0.834±0.149) was determined. Nonzero value of δ(E2/M1) questioned the present theoretical interpretation of low-lying levels of 227Th. Calculations performed prefer the 1/2+, 3/2+, and 3/2+ sequence instead of the adopted 1/2+, 5/2+ and 3/2+ one for the 0.0, 9.2, and 24.3 keV levels, respectively.

Structural and Parametric Optimization of S-CO2 Nuclear Power Plants.

The transition to the use of supercritical carbon dioxide as a working fluid for power generation units will significantly reduce the equipment′s overall dimensions while increasing fuel efficiency and environmental safety. Structural and parametric optimization of S–CO2 nuclear power plants was carried out to ensure the maximum efficiency of electricity production. Based on the results of mathematical modeling, it was found that the transition to a carbon dioxide working fluid for the nuclear power plant with the BREST–OD–300 reactor leads to an increase of efficiency from 39.8 to 43.1%. Nuclear power plant transition from the Rankine water cycle to the carbon dioxide Brayton cycle with recompression is reasonable at a working fluid temperature above 455 °C due to the carbon dioxide cycle′s more effective regeneration system.

Simulating low-energy neutrino interactions with MARLEY

Monte Carlo event generators are a critical tool for the interpretation of data obtained by neutrino experiments. Several modern event generators are available which are well-suited to the GeV energy scale used in studies of accelerator neutrinos. However, theoretical modeling differences make their immediate application to lower energies difficult. In this paper, I present a new event generator, MARLEY, which is designed to better address the simulation needs of the low-energy (tens of MeV and below) neutrino community. The code is written in C++14 with an optional interface to the popular ROOT data analysis framework. The current release of MARLEY (version 1.2.0) emphasizes simulations of the reaction 40Ar(νe,e−)40K⁎ but is extensible to other channels with suitable user input. This paper provides detailed documentation of MARLEY's implementation and usage, including guidance on how generated events may be analyzed and how MARLEY may be interfaced with external codes such as Geant4. Further information about MARLEY is available on the official website at http://www.marleygen.org. Program summaryProgram title:MARLEY 1.2.0CPC Library link to program files:https://doi.org/10.17632/4v7zxnc8j3.1Developer's respository link:http://github.com/MARLEY-MC/marleyCode Ocean capsule:https://codeocean.com/capsule/9868179Licensing provisions: GNU General Public License 3.0Programming language: C++14External routines/libraries used: GNU Scientific Library [1,2] (required), ROOT [3,4] (optional)Nature of problem: Simulation of neutrino-nucleus scattering events at energies of tens-of-MeV and belowSolution method: Initial two-to-two scattering kinematics are sampled using the allowed approximation differential cross section and tables of precomputed nuclear matrix elements. Subsequent de-excitations of the remnant nucleus are simulated using a Monte Carlo implementation of the Hauser-Feshbach statistical model and tabulated γ-ray decay schemes for discrete nuclear levels.Additional comments including restrictions and unusual features: Input data are provided with the code that are suitable for producing simulations of the charged-current reaction 40Ar(νe,e−)40K⁎, coherent elastic neutrino-nucleus scattering on spin-zero target nuclei, and neutrino-electron elastic scattering on any atomic target. Preparation of new reaction input files (whose format is documented in Appendix B) would enable other reaction channels and nuclear targets to be handled by the existing code framework. Although there is no maximum neutrino energy enforced by the code itself, realistic neutrino-nucleus scattering events may be generated up to roughly 50 MeV. Above this energy, the effects of forbidden nuclear transitions, which are neglected in the current treatment of the cross sections (see section 2.1), become increasingly important.

Nuclear Resonance Vibrational Spectroscopy: A Modern Tool to Pinpoint Site-Specific Cooperative Processes.

Nuclear resonant vibrational spectroscopy (NRVS) is a synchrotron radiation (SR)-based nuclear inelastic scattering spectroscopy that measures the phonons (i.e., vibrational modes) associated with the nuclear transition. It has distinct advantages over traditional vibration spectroscopy and has wide applications in physics, chemistry, bioinorganic chemistry, materials sciences, and geology, as well as many other research areas. In this article, we present a scientific and figurative description of this yet modern tool for the potential users in various research fields in the future. In addition to short discussions on its development history, principles, and other theoretical issues, the focus of this article is on the experimental aspects, such as the instruments, the practical measurement issues, the data process, and a few examples of its applications. The article concludes with introduction to non-57Fe NRVS and an outlook on the impact from the future upgrade of SR rings.

Constraints on Ξ− nuclear interactions from capture events in emulsion

Five Ξ−p→ΛΛ two-body capture events in 12C and 14N emulsion nuclei, in which a pair of single-Λ hypernuclei is formed and identified by their weak decay, have been observed in (K−,K+) emulsion exposures at KEK and J-PARC. Applying a Ξ−-nucleus optical potential methodology to study atomic and nuclear transitions, we confirm that these capture events occur from Coulomb assisted 1pΞ− nuclear states. Long-range ΞN shell-model correlations are found essential to achieve consistency between the 12C and 14N events. The resulting Ξ-nuclear interaction is strongly attractive, with Ξ potential depth in nuclear matter VΞ≳20 MeV. Implications to multi-strangeness features of dense matter are outlined.

Nuclear supersymmetry and quantum shape-phase transition

Nuclear supersymmetry and quantum shape-phase transition

The nuclear ground-state properties and stellar electron emission rates of 76Fe, 78Ni, 80Zn, 126Ru, 128Pd and 130Cd using RMF and pn-QRPA models

Our study consists of investigations of nuclear ground state properties and weak transition rates of even-even waiting point nuclei. The calculation was performed for N=50 and N=82 nuclei. The Relativistic Mean Field (RMF) model was used to explore the nuclear ground state properties of selected nuclei. The proton-neutron quasi particle random phase (pn-QRPA) model was used for the computation of allowed Gamow Teller (GT) and unique first-forbidden (U1F) transitions of the selected waiting point nuclei. The RMF approach with different density-dependent interactions, DD-ME2 and DD-PC1, was used to compute potential energy curves and surfaces, quadrupole moments, deformation parameters, binding energies, proton-neutron separation energies, charge, and radii. The RMF computed deformation parameters were used in the pn-QRPA model, as a free parameter, for the computation of GT and U1F weak transitions. We investigated three different sets of deformation parameter for the calculation of electron emission rates. The rates changed considerably with change in deformation parameter. We later investigated contribution of allowed GT and U1F rates and competition between positron capture and electron emission rates at high stellar temperatures. The computed positron capture rates were significant especially at low densities and high temperatures. The contribution of U1F rates to allowed GT appreciably reduced the total calculated half-lives. The comparison of our results with previous calculations and measurement is also shown. The pn-QRPA calculation including U1F contribution is in good agreement with the experimental data.

Spermatozoa retrieval in azoospermia and expression profile of JMJD1A, TNP2, and PRM2 in a subset of the Karachi population.

The difficulties encountered in surgical spermatozoa retrieval for intracytoplasmic sperm injection procedure in azoospermic men have stressed the dire need for a robust biomarker for the prediction of spermatozoa retrieval. Data have highlighted the role of JMJD1A (Jumonji domain-containing 1A), a histone H3K9 demethylase, and other nuclear proteins, protamines (PRM) and transition nuclear proteins (TNP), as biomarkers in male infertility. To access successful spermatozoa retrieval at the time of intracytoplasmic sperm injection by evaluating the mRNA expression profile of JMJD1A, TNP, and PRM in testicular tissue. About 100 azoospermic patients, who visited the Australian Concept Infertility Medical Center, Karachi for spermatozoa retrieval by testicular sperm extraction or microsurgical testicular spermextraction participated in the study. mRNA expression of the JMJD1A, TNP1, TNP2, PRM1, and PRM2 genes was determined. Patients were categorized into successful spermatozoa retrieval (n = 42) group and unsuccessful spermatozoa retrieval (n = 58) group. Azoospermic men in successful spermatozoa retrieval had significantly increased expression of JMJD1A, TNP2, and PRM2. The hormonal parameters - follicle-stimulating hormone, luteinizing hormone, and thyroid-stimulating hormone were significantly higher in unsuccessful spermatozoa retrieval. Multivariate analysis showed a significant association between JMJD1A, TNP2, PRM2, and successful spermatozoa retrieval. The area under the receiver operating characteristics curve showed a significant discriminatory ability to predict the spermatozoa retrieval outcome in azoospermic patients for mRNA expression of JMJD1A, TNP2, and PRM2 was 71, 72, and 73%, respectively. The area under the curve for follicle-stimulating hormone, luteinizing hormone, and thyroid-stimulating hormone was 0.67, 0.81, and 0.65, respectively. Our study demonstrates that the mRNA expression profile of JMJD1A, TNP2, and PRM2 along with hormonal parameters, is a useful marker to assess the probability of spermatozoa retrieval before intracytoplasmic sperm injection intervention. The probability of spermatozoa retrieval in azoospermic patients is increased when the mRNA expression profile of JMJD1A, TNP2, and PRM2 in testicular tissue is increased.

Experimental methods in chemical engineering: Mössbauer spectroscopy

AbstractWhen a free nucleus absorbs or emits a gamma ray, it recoils to conserve energy, just like a gun recoils after shooting a bullet. Nuclei bound to a crystal lattice conserve energy when they absorb or emit gamma rays from a nuclear transition as they are fixed so their movement is restricted. This restriction is recoilless nuclear resonance fluorescence—the Mössbauer effect. The energy transmitted through a sample reveals its electronic and molecular structure and magnetic properties but only when the atoms in the source and sample are the same isotope—57Co/57Fe is the most common couple. So, many of its applications are to identify iron species or how they change as a function of environmental conditions, like corrosion. A bibliometric map identified six major clusters centred around: nanoparticles and magnetite (Fe3O4), crystal structure and spectroscopy, oxidation and catalysis, X‐ray diffraction (XRD) and Raman spectroscopy, 57Fe and cathodes, and Co and thin films. In the last 30 years, the number of articles per year that mention the technique has hovered around 1250. More recently, Mössbauer spectroscopy has experienced a great rediscovery, particularly in the industrial sector for the solution of some problems, but also in space exploration.

QCD phase transition and equation of state of stellar strong interaction matter via Dyson\u2013Schwinger equation approach

We study the phase structure and phase transition of cold dense QCD matter via the Dyson–Schwinger equation approach. We take the rainbow approximation and the Gaussian-type gluon model. In order to guarantee that the quark number density begins to appear at the nuclear liquid-gas phase transition chemical potential, we propose a chemical potential dependent modification factor for the gluon model. We find that for the iso-symmetric quark matter, the modification reduces the chemical potential of the phase coexistence region of the first-order phase transition. We also implement the relativistic mean field theory to describe the hadron matter, and make use of the Maxwell and Gibbs construction method to study the phase transition of beta -equilibrium and charge neutral matter in compact stars. The results show that the phase transition will not happen in case of the Gaussian-type gluon model without any modification. The results also indicate that the upper boundary of the coexistence region should be larger than the current Nambu solution existing region. We also calculate the mass-radius relation of the compact stars, and find that the hadron-quark phase transition happens at too high chemical potential so that the maximum mass of the compact star is hardly affected by the hadron-quark phase transition.

Low-lying energy levels of 229Th35+ and the electronic bridge process

The nuclear transition between the ground and the low-energy isomeric state in the 229Th nucleus is of interest due to its high sensitivity to a hypothetical temporal variation of the fundamental constants and a possibility to build a very precise nuclear clock, but precise knowledge of the nuclear clock transition frequency is required. In this work, we estimate the probability of an electronic bridge (EB) process in 229Th35+, allowing to determine the nuclear transition frequency and reduce its uncertainty. Using configuration interaction methods, we calculated energies of the low-lying states of Th35+ and determined their uncertainties. Our calculations showed that the transition energy from the J = 15/2 state to the ground state, 8.31 eV, is close to the central value of the experimentally determined nuclear isomer energy, 8.19 eV, and practically coincides with the upper edge value, 8.31 eV. It opens new possibilities for a more precise measurement of the nuclear isomer energy using an EB process.

Investigation of the nuclear liquid-gas phase transition in the static AMD

Nuclear liquid-gas phase transitions are investigated in the framework of static antisymmetrized molecular dynamics (static AMD) model under either a constant volume or a constant pressure. A deuteron quadrupole momentum fluctuation thermometer is applied to extract the temperature of fragmenting systems of 36Ar and 100Sn. A plateau structure of caloric curves is observed under a constant volume for those system with a density ρ ⩽ 0.03 fm−3. A clear backbending in the caloric curves, which indicates a first order phase transition, is observed under a constant pressure with all pressures studied. The similar behavior of caloric curves of 36Ar and 100Sn systems indicates that there is no strong system size effect under a constant volume or a constant pressure. Both the mass distributions and the light particle multiplicities show a strong α clusterization at low excitation energies in the static AMD simulations. The liquid-gas phase transition measures of the multiplicity derivative (dM/dT) and the normalized variance of Z max (NVZ) are applied. The experimental caloric curves are also compared with those of 100Sn of the static AMD simulations under both the constant volume and the constant pressure conditions. Discussions are presented with the available experimental results and those from the static AMD simulations. Large errors in the experimental temperature measurements and those in the reconstruction technique for the primary fragmenting source hinder to draw a conclusion whether the phase transition occurs under either a constant volume or a constant pressure. This study suggests that different measures for the liquid-gas phase transitions should be examined besides the caloric curves in order to draw a conclusion.

Calculation of double-β decay half-lives using an improved Primakoff-Rosen formula * *Supported by the National Natural Science Foundation of China (U1731238, 11761161001, 11105079, 11535004, 11375086, 11975167, 12035011), the Science and Technology Development Fund (FDCT) of Macau (020/2014/A1, 008/2017/AFJ, 0042/2018/A2), the Science and Technology Foundation of Guizhou Province ((2016)4008, (2017)5726-37) and the foundation of Guizhou Provincial education Department (KY(2020)003)

A systematic analysis on experimental data of the half-lives of nuclear double- decays with two neutrinos ( ) is performed based on the analytical formula proposed by Primakoff and Rosen. We improve the formula by considering the shell effects and refining the energy dependence of the phase-space factor. This improved formula can closely describe all available experimental half-lives of decays, both for ground-state transitions and transitions from ground states of parent nuclei to the first excited states of daughter nuclei. The calculated half-lives agree with the experimental data of ground-state transitions of all known eleven nuclei with an average factor of 2.3. Further predictions are provided for -decay candidates with decay energies above 0.5 MeV. We compare different theoretical predictions and emphasize the importance of experimental measurements on the half-lives of double- transitions between the ground state of Ca, Ge, and Xe and the first excited states of their corresponding daughter nuclei, which will be very useful for understanding the underlying mechanisms of double- decays and for further studying the shell effects on nuclear transition matrix elements.

Coupling dynamical and statistical mechanisms for baryonic cluster production in nucleus collisions of intermediate and high energies

Central nucleus-nucleus collisions produce many new baryons and the nuclear clusters can be formed from these species. The phenomenological coalescence models were sufficiently good for description of light nuclei yields in a very broad range of collision energies. We demonstrate that in reality the coalescence process can be considered as 1) the formation of primary diluted excited baryon clusters and 2) their following statistical decay leading to the final cold fragment production. We argue that the formation of such excited systems from the interacting baryons is a natural consequence of the nuclear interaction at subnuclear densities resulting in the nuclear liquid-gas type phase transition in finite systems. In this way one can provide a consistent interpretation of the experimental fragment yields (FOPI data) including the important collision energy dependence in relativistic ion reactions. We investigate the regularities of this new kind of fragment production, for example, their yield, isospin, and kinetic energy characteristics. A generalization of such a clusterization mechanism for hypernuclear matter is suggested. The isotope yields and particle correlations should be adequate for studying these phenomena.

Highly Efficient Heavy Ion Acceleration from Laser Interaction with Dusty Plasma

Energetic heavy ions with short duration can be generated in the interaction of ultrashort ultraintense (USUI) laser pulse with solid matter. However, the energy conversion efficiency from laser to heavy ions is usually very low. Herein, a novel scheme for efficient transfer of USUI laser energy to the heavy ions of microscopic dust grains in dusty plasma is proposed. Due to the resulting ultraintense space‐charge field, the heavy ions expand isotropically together with the laser heated and expelled grain electrons as a plasma cloud on roughly the ion acoustic timescale. It is found that with 3.1 × 1020 W cm−2 USUI laser, one can produce hundreds‐megaelectronvolt C6+ ions with ≈60% energy transfer efficiency. In fact, up to 300 GeV Au79+ ions with ≈30% energy transfer efficiency can be obtained by using 8.8 × 1023 W cm−2 laser. This result suggests the possibility of using hundreds‐petawatt laser facility to investigate heavy‐ion collisions for nuclear state detection and quantum cardiodynamics phase transition.

Driven electronic bridge processes via defect states in Th229 -doped crystals

The electronic defect states resulting from doping $^{229}$Th in CaF$_2$ offer a unique opportunity to excite the nuclear isomeric state $^{229m}$Th at approximately 8 eV via electronic bridge mechanisms. We consider bridge schemes involving stimulated emission and absorption using an optical laser. The role of different multipole contributions, both for the emitted or absorbed photon and nuclear transition, to the total bridge rates are investigated theoretically. We show that the electric dipole component is dominant for the electronic bridge photon. In contradistinction, the electric quadrupole channel of the $^{229}$Th isomeric transition plays the dominant role for the bridge processes presented. The driven bridge rates are discussed in the context of background signals in the crystal environment and of implementation methods. We show that inverse electronic bridge processes quenching the isomeric state population can improve the performance of a solid-state nuclear clock based on $^{229m}$Th.

Nuclear clocks for testing fundamental physics

The low-energy, long-lived isomer in 229Th, first studied in the 1970s as an exotic feature in nuclear physics, continues to inspire a multidisciplinary community of physicists. It has stimulated innovative ideas and studies that expand the understanding of atomic and nuclear structure of heavy elements and of the interaction of nuclei with bound electrons and coherent light. Using the nuclear resonance frequency, determined by the strong and electromagnetic interactions inside the nucleus, it is possible to build a highly precise nuclear clock that will be fundamentally different from all other atomic clocks based on resonant frequencies of the electron shell. The nuclear clock will open opportunities for highly sensitive tests of fundamental principles of physics, particularly in searches for violations of Einstein’s equivalence principle and for new particles and interactions beyond the standard model. It has been proposed to use the nuclear clock to search for variations of the electromagnetic and strong coupling constants and for dark matter searches. The 229Th nuclear optical clock still represents a major challenge in view of the tremendous gap of nearly 17 orders of magnitude between the present uncertainty in the nuclear transition frequency (about 0.2 eV, corresponding to ∼48 THz) and the natural linewidth (in the mHz range). Significant experimental progress has been achieved in recent years, which will be briefly reviewed. Moreover, a research strategy will be outlined to consolidate our present knowledge about essential 229mTh properties, to determine the nuclear transition frequency with laser spectroscopic precision, realize different types of nuclear clocks and apply them in precision frequency comparisons with optical atomic clocks to test fundamental physics. Two avenues will be discussed: laser-cooled trapped 229Th ions that allow experiments with complete control on the nucleus–electron interaction and minimal systematic frequency shifts, and Th-doped solids enabling experiments at high particle number and in different electronic environments.

Dirac–Fock internal conversion coefficients at low [formula omitted]-ray energy

Presented here are internal conversion coefficients (ICCs) for nuclear transitions of low γ-ray energies from 0.1keV to 1keV in elements with 10≤Z≤118. The low-energy nuclear transitions attract significant interest since the novel experimental technique and methods make it possible to study the transitions as well as to discover new low-lying isomers. Our ICC calculations are shown to be in excellent agreement with experimental data for the fairly low-energy nuclear transitions. The calculations are based on the Dirac–Fock method. The vacancy in the atomic shell from which an electron has been emitted is taken into account in the framework of the frozen core approximation. Experimental binding energies are used for elements Z≤95. Theoretical binding energies obtained in a good approximation are used for Z≥96. Peculiarities of the ICC behavior at low energies are considered. The resonance-like structure of ICC and the drastic decrease in magnitude as the energy increases are demonstrated to be responsible for a pronounced dependence of ICC on theoretical assumptions underlying the calculations. We discuss the influence on the low-energy ICCs of the exact taking account the exchange interaction between electrons, the inclusion of the vacancy after conversion, and a credible choice of the binding energy.