Nuclear Structure Research Articles

The unique role of vimentin in the intermediate filament proteins family

Intermediate filaments (IFs), being traditionally the least studied component of the cytoskeleton, have begun to receive more attention in recent years. IFs are found in different cell types and are specific to them. Accumulated data have shifted the paradigm about the role of IFs as structures that merely provide mechanical strength to the cell. In addition to this role, IFs have been shown to participate in maintaining cell shape and strengthening cell adhesion. The data have also been obtained that point out to the role of IFs in a number of other biological processes, including organization of microtubules and microfilaments, regulation of nuclear structure and activity, cell cycle control, and regulation of signal transduction pathways. They are also actively involved in the regulation of several aspects of intracellular transport. Among the intermediate filament proteins, vimentin is of particular interest for researchers. Vimentin has been shown to be associated with a range of diseases, including cancer, cataracts, Crohn’s disease, rheumatoid arthritis, and HIV. In this review, we focus almost exclusively on vimentin and the currently known functions of vimentin intermediate filaments (VIFs). This is due to the structural features of vimentin, biological functions of its domains, and its involvement in the regulation of a wide range of basic cellular functions, and its role in the development of human diseases. Particular attention in the review will be paid to comparing the role of VIFs with the role of intermediate filaments consisting of other proteins in cell physiology.

Imaging shapes of atomic nuclei in high-energy nuclear collisions.

Atomic nuclei are self-organized, many-body quantum systems bound by strong nuclear forces within femtometre-scale space. These complex systems manifest a variety of shapes1-3, traditionally explored using non-invasive spectroscopic techniques at low energies4,5. However, at these energies, their instantaneous shapes are obscured by long-timescale quantum fluctuations, making direct observation challenging. Here we introduce the collective-flow-assisted nuclear shape-imaging method, which images the nuclear global shape by colliding them at ultrarelativistic speeds and analysing the collective response of outgoing debris. This technique captures a collision-specific snapshot of the spatial matter distribution within the nuclei, which, through the hydrodynamic expansion, imprints patterns on the particle momentum distribution observed in detectors6,7. We benchmark this method in collisions of ground-state uranium-238 nuclei, known for their elongated, axial-symmetric shape. Our findings show a large deformation with a slight deviation from axial symmetry in the nuclear ground state, aligning broadly with previous low-energy experiments. This approach offers a new method for imaging nuclear shapes, enhances our understanding of the initial conditions in high-energy collisions and addresses the important issue of nuclear structure evolution across energy scales.

Impact of reactor neutrino uncertainties on coherent scattering's discovery potential

Abstract Nuclear power reactors are the most intense man-made source of antineutrino's and have long been recognized as promising sources for coherent elastic neutrino-nucleus scattering (CE$\nu$NS) studies. Its observation and the spectral shape of the associated recoil spectrum is sensitive to a variety of exotic new physics scenarios and many experimental efforts are underway. Within the context of the reactor antineutrino anomaly, which initially indicated eV-scale sterile neutrino's, the modeling of the reactor antineutrino spectrum has seen a significant evolution in the last decade. Even so, uncertainties remain due to a variety of nuclear structure effects, incomplete information in nuclear databases and fission dynamics complexities. Here, we investigate the effects of these uncertainties on one's ability to accurately distinguish new physics signals. For the scenarios discussed here, we find that reactor spectral uncertainties are similar in magnitude to the projected sensitivities pointing towards a need for $\beta$ spectroscopy measurements below the inverse $\beta$ decay threshold.

A Case Study: Implementation of Innovative Educational Strategies on Teaching Nuclear Chemistry at the College of Engineering Laguna State Polytechnic University – Sta. Cruz Campus

The outcome of the evaluation shows the level of students’ consistency with the expected learning outcomes and identifies the weaknesses that are present in them for training rationale. As a result, the data highlight the necessity of the creation of certain instructional techniques that would help the students confront the challenges that arise due to nuclear chemistry. Probably this would improve the understanding p of nuclear structure and properties when jigsaw and practical strategies are used to teach. A noticeable growth of homogeneity between subjects around the engineering specialization spectrum provides an idea of what works best. High marks achieved early may indicate deficits within the domain while progressing uniformly points towards learning needs being unaddressed. Learners’ interests and the perception of their knowledge may be enhanced by employing diverse tasking and assessment strategies within the instructional applications. Nuclear chemistry may remain a challenging science that does not motivate students to learn or retain information if its delivery does not change. The action plan is part of follow-up activities like conducting active learning through group work and experiments. Such procedures are reasonable as they provide and support evidence of understanding through feedback. Adjust the existing curriculum as a pedagogical strategy for generating credible new information supported by practical benefits. Impart additional learning and teaching in a way that assists challenged or struggling learners in adapting. Be open and discuss positive outcomes so that students become more self-assured and confident. As the above recommendations and action plans were also suggested by them, it is expected that engineering students who adopt nuclear chemistry will have their education experiences enhanced. This strategic approach does more than solve the challenges noted but also employs the resources and opportunities available to promote understanding of the subject. It is also expected that these strategies will be subjected to constant evaluation to improve their effectiveness and the students’ addresses.

Seismic fragility analysis of nuclear containment structure with Bayesian cloud analysis framework

Nuclear containment structure plays a critical role in safe operation of nuclear power plants. Seismic safety of nuclear power plant structures has become a hot issue in nuclear engineering community following Fukushima nuclear accident. Seismic fragility analysis, as a key element in probabilistic safety assessment of nuclear power plants, is widely used in nuclear power plant structures. This study presents an innovative method for seismic fragility analysis of engineering structures. The proposed methodology combines conventional Cloud analysis method and Bayesian framework. The accuracy and efficiency of the proposed methodology were demonstrated by a single-degree-of-freedom system, heavy computational efforts but high accuracy seismic fragility analysis method was adopted for comparison. Seismic fragility analysis of a typical prestressed concrete nuclear containment structure was analyzed using the proposed method. Results indicated that method proposed in this study can improve the accuracy of seismic fragility analysis. Furthermore, with the enhance of performance level, the increasing ratios for median seismic capacity of the nuclear containment structure was decreasing.

Carbon quantum dots in breast cancer modulate cellular migration via cytoskeletal and nuclear structure

Carbon nanomaterials have been widely applied for cutting edge therapeutic applications as they offer tunable physio-chemical properties with economic scale-up options. Nuclear delivery of cancer drugs has been of prime focus since it controls important cellular signaling functions leading to greater anti-cancer drug efficacies. Better cellular drug uptake per unit drug injection drastically reduces severe side-effects of cancer therapies. Similarly, carbon dots (CDs) uptaken by the nucleus can also be used to set-up cutting edge nano delivery systems. In an earlier paper, we showed the cellular uptake and plasma membrane impact of combustion generated yellow luminescing CDs produced by our group from fuel rich combustion reactors in a one-step tunable production. In this paper, we aim to specifically study the nucleus by establishing the uptake kinetics of these combustion-generated yellow luminescing CDs. At sub-lethal doses, after crossing the plasma membrane, they impact the actin and microtubule mesh, affecting cell adhesion and migration; enter nucleus by diffusion processes; modify the overall appearance of the nucleus in terms of morphology; and alter chromatin condensation. We thus establish how this one-step produced, cost and bulk production friendly carbon dots from fuel rich combustion flames can be innovatively repurposed as potential nano delivery agents in cancer cells.

Pnn deficiency alters expressions of calcium handling proteins and impairs nuclear envelope structure in cardiomyocytes

Abstract Pnn is a multi-functional protein playing roles in the regulation of gene transcription, mRNA alternative splicing, as well as cell-cell connection. Previous studies suggested an association between Pnn genetic defects and arrhythmogenic right ventricular cardiomyopathy (ARVC) in human. In this study, we applied an inducible cardiomyocyte-specific Pnn depletion mouse model (Myh6-CreERT2, Pnnflox/flox) to determine the impact of loss of Pnn on cardiac structure and function in mice. Six weeks after inducing Pnn gene disruption, electrocardiographic abnormalities, ventricular dilatation, and reduced left ventricular ejection fraction (LVEF) were observed in mice with loss of Pnn in cardiomyocytes. Histopathological examinations showed that the proliferation of cardiac fibroblasts and expression of α-smooth muscle actin were increased with Pnn depletion, while the cell-cell connection between cardiomyocytes were impaired. In addition to impaired intercalated discs, loss of Pnn also altered the distribution and expression of nuclear envelope proteins and the linker of nucleoskeleton and cytoskeleton (LINC) complex proteins, such as nuclear lamins, Emerin, and SUNs, in cardiomyocytes. Microarray analysis as well as subsequent RT-PCR and Western blots also indicated that loss of Pnn regulated myocardial expressions of genes responsible for calcium handling, such as RYR2, Atp2a2, Slc8a1, and Kcnj3. Furthermore, infiltrations of macrophages and neutrophiles were observed in the myocardium with Pnn depletion, while expression levels of oxidative stress-associated proteins were also significantly regulated by Pnn depletion. In conclusion, Pnn plays an essential role in the maintenance of intercalated disc integrity and nuclear envelope structure of cardiomyocytes, while cardiomyocyte-specific loss of Pnn impairs the calcium handling and leads to arrhythmogenic dilated cardiomyopathy in mice.Cardiac MRI of mice with Pnn depletionMyocardial expression of SUN2 and Emerin

Retinal G-protein-coupled receptor deletion exacerbates AMD-like changes via the PINK1-parkin pathway under oxidative stress.

The intake of high dietary fat has been correlated with the progression of age-related macular degeneration (AMD), affecting the function of the retinal pigment epithelium through oxidative stress. A high-fat diet (HFD) can lead to lipid metabolism disorders, excessive production of circulating free fatty acids, and systemic inflammation by aggravating the degree of oxidative stress. Deletion of the retinal G-protein-coupled receptor (RGR-d) has been identified in drusen. In this study, we investigated how the RGR-d exacerbates AMD-like changes under oxidative stress, both invivo and invitro. Fundus atrophy became evident, at 12 months old, particularly in the RGR-d + HFD group, and fluorescence angiography revealed narrower retinal vessels and a reduced perfusion area in the peripheral retina. Although rod electroretinography revealed decreasing trends in the a- and b-wave amplitudes in the RGR-d + HFD group at 12 months, the changes were not statistically significant. Mice in the RGR-d + HFD group showed a significantly thinner and more fragile retinal morphology than those in the WT + HFD group, with disordered and discontinuous pigment distribution in the RGR-d + HFD mice. Transmission electron microscopy revealed a thickened Bruch's membrane along the choriocapillaris endothelial cell wall in the RGR-d + HFD mice, and the outer nuclear layer structure appeared disorganized, with reduced nuclear density. Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated significantly lower levels of 25(OH)-vitamin D3 metabolites in the RGR-d + HFD group. Under oxidative stress, RGR-d localized to the mitochondria and reduced the levels of the PINK1-parkin pathway. RGR-d mice fed an HFD were used as a new animal model of dry AMD. Under high-fat-induced oxidative stress, RGR-d accumulated in the mitochondria, disrupting normal mitophagy and causing cellular damage, thus exacerbating AMD-like changes both invivo and invitro.

Emerin preserves stem cell survival through maintenance of centrosome and nuclear lamina structure.

Drosophila female germline stem cells (GSCs) complete asymmetric mitosis in the presence of an intact, but permeable, nuclear envelope and nuclear lamina (NL). This asymmetric division requires a modified centrosome cycle, wherein mitotic centrosomes with mature pericentriolar material (PCM) embed in the NL and interphase centrosomes with reduced PCM leave the NL. This centrosome cycle requires emerin, a NL protein critical for GSC survival and germ cell differentiation. In emerin mutants, interphase GSCs centrosomes retain excess PCM, remain embedded in the NL and nucleate microtubule asters at positions of NL distortion. Here, we address contributions of abnormal interphase centrosomes to GSC loss. Remarkably, reducing interphase PCM in emerin mutants rescues GSC survival and partially restores germ cell differentiation. Direct tests of effects of abnormal centrosomes were achieved by expression of constitutively active Polo kinase that drove enlargement of interphase centrosomes in wild type GSCs. Notably, these conditions failed to alter NL structure or decrease GSC survival. However, coupling enlarged interphase centrosomes with nuclear distortion promoted GSC loss. These studies establish that emerin maintains centrosome structure to preserve stem cell survival.

A study of nuclear structure of light nuclei at the electron–ion collider

A study of nuclear structure of light nuclei at the electron–ion collider

Asymptotic Normalization Coefficient Investigation of the 17O(d, p) Transfer for Astrophysical Application to the 17O(n, α)14C Reaction at Low Energies

Indirect methods have proven to be a complementary approach for extending our knowledge of nuclear structure and low-energy cross sections. Among these, the neutron-induced reaction cross sections appear to be of particular interest since their role both for unstable and stable beams. In view of this, we report here the combined study of the 17O(n, α)14C reaction accomplished by the Trojan Horse Method (THM) and the asymptotic normalization coefficient (ANC) method. The low-lying 8038, 8125, 8213, and 8282 keV resonances in 18O are studied, and their Γ n are derived. A comparison with recent direct data and recent THM experimental data is presented. The independent ANC investigation corroborates our previous THM results, confirms the consistence of the two indirect investigations, and shows new frontiers for neutron-induced reactions with radioactive ion beams. Moreover, we examined the impact of adopting the newly recommended 17O(n, α)14C reaction rate on asymptotic giant branch stars' nucleosynthesis. Our findings reveal significant variations (≳10%) in the production of the neutron-rich heavy isotopes sensitive to neutron density, underlining the neutron-poisoning effect of 17O on the s-process.

Neutron and gamma radiation effects on thermal storage properties of polyethylene wax

Several nuclear reactors use ice condensers to condense steam in the case of a loss of coolant accident. These ice condensers have many problems that could be alleviated by using another material. The effects of low-dose neutron and gamma radiation on the thermal properties of polyethylene wax (PEW) were investigated for this purpose. PEW was irradiated in the Missouri University of Science and Technology Research Reactor (MSTR), the University of Missouri Cyclotron (MUC) and the University of Missouri Research Reactor (MURR) up to doses equivalent to 10 months in a nuclear power reactor's containment structure. The melting temperature and latent heat of fusion were determined using differential scanning calorimetry (DSC). Changes in the molecular bonds was determined using Raman spectroscopy. It was found that there was not a significant change in the thermal properties nor bonding over the investigated doses. This suggests that organic PCMs could be reliable alternatives to ice in nuclear reactor containment applications. The measured melting peak was found to be significantly wider expected by the suppliers' description. The ramifications of wide melting peaks are discussed in the context of reactor accident analysis and further experiments are suggested.

Ferrocenyl Dithiophosphonate Ag(I) Complexes: Synthesis, Structures, Luminescence, and Electrocatalytic Water Splitting Tuned by Nuclearity and Ligands.

The heterometallic [Ag(I)/Fe(II)] molecular electrocatalysts for hydrogen production were introduced here to recognize the mutual role of metallic nuclearity and ligand engineering. A series of ferrocenyl dithiophosphonate stabilized mononuclear [Ag(PPh3)2{S2PFc(OR)}] {where R=Me (1), Et (2), nPr (3), iPr (4), iAmyl (5); Fc=Fe (ɳ5-C5H4) (ɳ5-C5H5)} and dinuclear [Ag(PPh3){S2PFc(OR}]2 {where R=Et (2 a), and nPr (3 a)} complexes were synthesized and characterized by SCXRD, NMR (31P and 1H), ESI-MS, UV-Vis, and FT-IR spectroscopy. The comparative electrocatalytic HER behavior of 1-5 and 2 a-3 a showed effective current density of 1 mA/cm2 with overpotentials ranging from 772 to 991 mV, demonstrating the influence of extended and branched carbon chains in dithiophosphonates and metallic (mono-/di-) nuclearity, which correlates with documented tetra-nuclear [Ag4(S2PFc(OnPr)4], 6. DFT study suggests the coordinated (μ1-S) site of ligands is the reactivity center and the adsorption energy of intermediate [H*-SM] varies with the engineering of ligand and nuclearity. A catalytic mechanism using mononuclear (1) and di-nuclear (2 a) was proposed with the assistance of DFT. Each complex, being the first example of Ag(I) dithiophosphonates, exhibits intense photoluminescence with high quantum yields ranging from 33 % to 67 %. These results link the lower nuclearity structures to their physical and catalytic properties.

Modification of Quark-Gluon Distributions in Nuclei by Correlated Nucleon Pairs.

We extend the QCD Parton Model analysis using a factorized nuclear structure model incorporating individual nucleons and pairs of correlated nucleons. Our analysis of high-energy data from lepton deep-inelastic scattering, Drell-Yan, and W and Z boson production simultaneously extracts the universal effective distribution of quarks and gluons inside correlated nucleon pairs, and their nucleus-specific fractions. Such successful extraction of these universal distributions marks a significant advance in our understanding of nuclear structure properties connecting nucleon- and parton-level quantities.

Estimates of natural frequencies for nuclear vibration, and an assessment of the feasibility of selective ultrasound ablation of cancer cells

Selective ablation of cancer cells by ultrasound would be transformative for cancer therapy, but has not yet been possible. A key challenge is that cancerous and non-cancerous cells typically have similar acoustic impedance and are thus indistinguishable as materials in their responses to ultrasound. However, in certain cancers, cytoskeletal and nuclear lamin structures differ between healthy and malignant cells, opening the possibility of exploiting structural differences that manifest as different vibrational responses. To assess the possibility that the nuclei of certain cancerous cells might vibrate at different frequencies, we measured sizes and effective indentation moduli of a range of cancerous and non-cancerous cells from several cell lines and regions of the brain, and estimated the natural frequencies for nuclear vibration. Results suggest a potential difference in natural frequency for nuclear vibration between certain cancerous and non-cancerous cells, on the order of tens of kHz. This gap is potentially sufficient for selective ablation and motivates future experimentation on these specific cell types.

JAK inhibitors in systemic lupus erythematosus: Translating pathogenesis into therapy.

Systemic lupus erythematosus (SLE) is a complex multi-organ autoimmune disease marked by the production of autoantibodies against nuclear structures, formation of immune complexes, and chronic inflammation triggered by their tissular deposition. SLE is characterized by alternating periods of relapse and remission and each flare has the potential to cause new organ damage related to either the disease process or the medication toxicity. Despite remarkable progress across its multiple domains, SLE is still an area with many unmet needs, calling for innovative and practical solutions. The efforts of the drug development programme in lupus have led to considerable growth in the last decade, owing to the approval of belimumab, anifrolumab, and voclosporin. The increasing understanding of the pathogenesis of the disease has enabled the exploration of novel therapeutic strategies. New discoveries in the intricate cytokine kaleidoscope of lupus have made the concept of targeted therapy an attractive and promising research focus. JAK inhibitors are oral targeted therapies approved for a wide variety of diseases across the Rheumatology, Gastroenterology, Dermatology, and Haematology fields. Multiple JAKis are currently being investigated in SLE. This paper aims to summarize existing data coming from both clinical trials and case reports regarding the use of JAK inhibitors in SLE.

Distilling the Essential Elements of Nuclear Binding via Neural-Network Quantum States.

To distill the essential elements of nuclear binding, we seek the simplest Hamiltonian capable of modeling atomic nuclei with percent-level accuracy. A critical aspect of this endeavor consists of accurately solving the quantum many-body problem without incurring an exponential computing cost with the number of nucleons. We address this challenge by leveraging a variational MonteCarlo method based on a highly expressive neural-network quantum state ansatz. In addition to computing binding energies and charge radii of nuclei with up to A=20 nucleons, by evaluating their magnetic moments, we demonstrate that neural-network quantum states are able to correctly capture the self-emerging nuclear shell structure. To this end, we introduce a novel computational protocol based on adding an external magnetic field to the nuclear Hamiltonian, which allows the neural network to learn the preferred polarization of the nucleus within the given magnetic field.

Structure of the Atomic Nucleus: Yesterday and Today

Structure of the Atomic Nucleus: Yesterday and Today

Soil-structure interaction analysis of nuclear power plant structure using multi-step method in time-domain

Recently, several countries have experienced strong earthquakes, and there has been growing interest in the seismic design of structures. Particularly, consideration of soil-structure interaction (SSI) has become important when performing seismic response analysis for nuclear power plant (NPP) structures. A seismic analysis method that considers SSI in the time domain has been proposed in previous studies. This method is applicable to the seismic response of structures, because it can consider the influence of the SSI effect with the impedance function in the frequency domain and simultaneously considers the structural nonlinearity. However, it has only been applied to the structure comprising a single beam-stick. In this study, a modified method for applying it to more general structures is proposed, and its applicability is validated with an actual reactor containment building (RCB) structure comprising a three beam-sticks. Validation was performed by comparing the seismic responses with those of ACS SASSI. Using the proposed method, SSI analysis was performed with three soil profiles and the results were compared to investigate the effect of SSI on seismic responses, including the in-structure response spectrum (ISRS) and time history acceleration. For more realistic analysis, soil profile and earthquake input motion occurred in South Korea are adopted. Further, a multi-step method considering nonlinear behavior was also performed and compared with the linear case.

Study on microwave absorbing properties of reduced graphene oxide@Co/Fe81.5Si3B9P3C1Cu1Ti1.5 amorphous nanocrystalline composite

Electromagnetic pollution problems and military stealth technology need to be solved, the development of new wave absorbing materials has been imminent. In this study, reduced graphene oxide@Co (rGO@Co) powder is obtained by alcoholthermal method, afterwards the different contents of rGO@Co powders are also compounded with Fe81.5Si3B9P3C1Cu1Ti1.5 nanocrystalline powder by high-energy ball milling, obtaining rGO@Co/Fe81.5Si3B9P3C1Cu1Ti1.5 nanocrystalline composite powder, and powder morphology, the nuclear layer structure, soft magnetic properties and corresponding absorbing properties of the materials are studied. The research results are that rGO coats Co and Fe-based nanocrystalline of double magnetic cores in the composite powder, which realizes the synergy of the two magnetic cores to enhance the magnetic loss, is also compatible with the dielectric loss of rGO, and also improves the impedance matching. The minimum reflection loss (RLmin) is −44.18 dB, and the maximum effective absorption bandwidth (EAB) is 5.03 GHz in the amorphous nanocrystalline alloy matrix. When the addition of rGO@Co powder is 1 wt%, the RLmin of composite powder is −52.41 dB (3 mm), which is increased by 18.6 %. The EAB is 6.07 GHz (2 mm), which is increased by 20.7 %.