Nuclear Model Research Articles

OpenNucleome for high-resolution nuclear structural and dynamical modeling

The intricate structural organization of the human nucleus is fundamental to cellular function and gene regulation. Recent advancements in experimental techniques, including high-throughput sequencing and microscopy, have provided valuable insights into nuclear organization. Computational modeling has played significant roles in interpreting experimental observations by reconstructing high-resolution structural ensembles and uncovering organization principles. However, the absence of standardized modeling tools poses challenges for furthering nuclear investigations. We present OpenNucleome—an open-source software designed for conducting GPU-accelerated molecular dynamics simulations of the human nucleus. OpenNucleome offers particle-based representations of chromosomes at a resolution of 100 KB, encompassing nuclear lamina, nucleoli, and speckles. This software furnishes highly accurate structural models of nuclear architecture, affording the means for dynamic simulations of condensate formation, fusion, and exploration of non-equilibrium effects. We applied OpenNucleome to uncover the mechanisms driving the emergence of ‘fixed points’ within the nucleus—signifying genomic loci robustly anchored in proximity to specific nuclear bodies for functional purposes. This anchoring remains resilient even amidst significant fluctuations in chromosome radial positions and nuclear shapes within individual cells. Our findings lend support to a nuclear zoning model that elucidates genome functionality. We anticipate OpenNucleome to serve as a valuable tool for nuclear investigations, streamlining mechanistic explorations and enhancing the interpretation of experimental observations.

Measurements of the 128Te(n, 2n)127m,gTe reaction cross sections and isomeric cross section ratio of 127m,gTe at the neutron energy of 14 MeV* *Supported by the National Natural Science Foundation of China (12165006, 12375295)

In this study, measurements of the 128Te(n, 2n)127m,gTe reaction cross sections and the computation of the isomeric cross section ratio were performed around the neutron energy of 13−15 MeV. We used a γ-ray spectrometric technique to conduct the measurements. The neutron energy was produced by the 3H(d,n)4He reaction. For the 128Te(n, 2n)127m,gTe reaction, the excited state, ground state, total cross section, and isomeric cross section ratio were determined using the TALYS-1.96 code, a theoretical nuclear model that allows for variations in density options. The initial experimental data, assessed nuclear data, and theoretical calculations based on the TALYS-1.96 algorithm were compared with the measurement results. The new data produced by this study are essential for validating nuclear models and establishing parameters for nuclear reactions.

The electric dipole characteristics of well-deformed 171,173Yb

The electric dipole response of well-deformed 171,173Yb in the giant dipole resonance (GDR) and pygmy dipole resonance (PDR) range has been theoretically analyzed using the translation and Galileo invariant quasiparticle phonon nuclear model (TGI-QPNM). The TGI-QPNM consists of an axially symmetric Woods-Saxon Potential, monopole pairing, dipole-dipole residual interaction, and the restoration terms for broken translation and Galilean symmetries. Numerical calculations show the existence of considerable E1 excitations around the neutron separation threshold (S n ) in both isotopes. The TGI-QPNM results of the photoabsorption cross-section give a double-humped shape in both nuclei, consistent with the available experimental data. The integrated moments (σ 0, σ −1) and the centroid energies in the GDR region are also reproduced well.

Integrated photonuclear cross sections in the giant dipole resonance of odd-mass actinide nuclei

This study explores the integrated total photonuclear cross section (σ0) within the context of the giant dipole resonance (GDR) in odd-mass actinide nuclei. Using artificial neural networks (ANNs) and adaptive neuro-fuzzy ınference system (ANFIS) machine learning algorithms, we analyze the GDR behaviors associated with the σ0 values in these nuclei. The modeling results obtained from ANFIS and ANN are compared among themselves and with the Translational Galilean Invariant Quasiparticle Phonon Nuclear Model (TGI-QPNM) and experimental data. Machine learning analysis and TGI-QPNM results provide valuable insights into the GDR characteristics of odd-mass actinides, shedding light on their photonuclear properties. The ANFIS model has achieved an R2 value of 0.98 and an RMSE of 0.19, while the ANN model (LM) has yielded an R2 value of 0.95 and an RMSE of 0.24. These findings deepen our understanding of nuclear physics, underscoring the role of artificial intelligence techniques in deciphering complex phenomena within nuclear structures. In conclusion, our study suggests that the ANFIS model, in agreement with TGI-QPNM results, generally outperforms the ANN (LM) method and could be a more effective tool for estimating the energy-weighted sum rule for GDR.

High-Fidelity Multiphysics Modeling of a Heat Pipe Microreactor Using BlueCrab

Researchers who are actively developing nuclear microreactors are planning to employ innovative designs and features using traditional commercial modeling tools that may be inadequate for their design and licensing activities. The codes developed under the U.S. Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) program provide flexibility in terms of geometry modeling and multiphysics coupling and are particularly well suited for modeling novel microreactor concepts. To test the maturity of these codes, this paper introduces a conceptual heat pipe microreactor (HP-MR) designed to gather various technologies of interest to microreactor developers such as control drums, heat pipes, and hydride moderators. The objective of this effort is to demonstrate NEAMS tools capability to perform high-fidelity multiphysics simulations, using coupled neutronics (via the Griffin code), heat conduction (via the BISON code), heat pipe modeling (via the Sockeye code), and hydrogen redistribution in hydride metal moderator (via the SWIFT code). Codes are coupled in-memory through the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework, which permits flexible multiphysics data transfer schemes. The analysis confirmed two key aspects of the HP-MR concept: (1) its ability to follow the power load requested from the heat pipe and (2) its ability to avoid heat pipe cascading failure unless designed with high power close to operating failure limits of its heat pipes. The developed computational model was distributed publicly on the Virtual Test Bed for training purposes to accelerate adoption by industry and to provide a high-fidelity multiphysics solution for benchmarking against other tools. Additional multiphysics analyses including other transients and coupled physics were identified as necessary future work, together with a focus on validating multiphysics behavior against experiments.

Higher forbidden unique β− decay transitions and shell-model interpretation

In the present work, we have predicted the half-lives for the β− decay for higher forbidden unique transitions in the mass range of nuclei from A = 40-138. For these transitions, the experimental data for half-lives are not available except for a few cases. The calculations for half-lives are performed within the framework of the nuclear shell model (SM). We have used the effective interactions sdpf-mu, gxpf1a, gwbxg, G-matrix, snet, sn100pn, and jj56pnb to perform the SM calculations in different mass regions. A comprehensive discussion has been made between the SM predicted half-lives and the scaled half-lives from proton-neutron quasiparticle random-phase approximation (pnQRPA). The results of the present study will be useful to plan new experiments to measure half-lives for these higher forbidden unique β− transitions.

Precision in medical isotope production: Nuclear model calculations using artificial neural networks

In this groundbreaking study, artificial neural networks (ANNs) are employed to predict the production cross-sections of crucial radioisotopes, namely 18O, 209Bi, 232Th, and 68Zn, via the (p,n) reaction. We employed a comparative approach to validate the ANN model's predictions by comparing them to outputs generated by established nuclear reaction codes (TALYS 1.9, EMPIRE-3.2 (Malta)) and data from the authoritative source, the Experimental Nuclear Reaction Data (EXFOR).Motivated by the increasing demand for radioisotopes in precise medical diagnostics and successful therapies, this study focuses on investigating methods and new techniques for determining production cross-sections with high accuracy, which are crucial for the consistent supply of vital radioisotopes. In line with this objective, the ANN model demonstrated exceptional performance, achieving remarkably high correlation coefficients, exceeding 0.999 for training and all data, and reaching 0.98665 for testing. Supportive of this, the high correlation coefficients indicate that the ANN estimations effectively match experimental data. Significantly, our findings illustrate the potential of ANNs as a promising alternative for estimating the production cross-sections of 18O, 209Bi, 232Th, and 68Zn, with the possibility of extending this application to other medically relevant radioisotopes.

Conceptual design and optimization of heat rejection system for nuclear reactor coupled with supercritical carbon dioxide Brayton cycle used on Mars

During the conceptual design of the Mars surface nuclear reactor coupled with supercritical carbon dioxide Brayton cycle, the heat rejection system occupies most of the weight, and reducing the weight of heat rejection system can effectively cut down the transportation cost from Earth to Mars. This paper explored the feasibility of adopting a combination of heat pipe cooling device and convective heat exchanger to design the heat rejection system for the Mars surface nuclear power station, established flow and heat transfer model and weight model, developed a thermal-hydraulic design program for the heat rejection system, and verified its accuracy; then, the NSGA-II multi-objective optimization method is used to optimize the weight of heat rejection system. Pareto front shows that with higher heat rejection proportion of convective heat exchanger, corresponding inlet velocity of Mars' atmosphere should also be increased. As the optimization result of heat rejection system, the ratio of weight to heat rejection is between 0.94 kg/kW and 2.92 kg/kW, and the maximum power consumption of convective heat exchanger accounts for 3.29% of the total power generation.

Nuclear matrix elements of neutrinoless double-beta decay in covariant density functional theory with different mechanisms

Nuclear matrix elements (NMEs) for neutrinoless double-beta (0νββ) decay in candidate nuclei play a crucial role in interpreting results from current experiments and in designing future ones. Accurate NME values serve as important nuclear inputs for constraining parameters in new physics, such as neutrino mass and the Wilson coefficients of lepton-number-violating (LNV) operators. In this study, we present a comprehensive calculation of NMEs for 0νββ decay in 76Ge, 82Se, 100Mo, 130Te, and 136Xe, using nuclear wave functions obtained from multi-reference covariant density functional theory (MR-CDFT). We employ three types of transition potentials at the leading order in chiral effective field theory. Our results, along with recent data, are utilized to constrain the coefficients of LNV operators. The results demonstrate that the combined NMEs based on the Feynman diagrams at the hadronic scale for the nonstandard mechanisms leads to the uncertainty by different nuclear models comparable to that for the standard mechanism. The use of NMEs from various nuclear models does not dramatically change the parameter space intervals for the coefficients, although MR-CDFT yields the most stringent constraint. Furthermore, our NMEs can also be used to perform a more comprehensive analysis with multiple isotopes.

The Impact of Tourism Development on Mosuo Marriage and Family

Tourism development has had a significant impact on the contemporary social transformation of the Mosuo people, especially on their marriage and family. Since the rise of tourism in the Lugu Lake area, the Mosuo society has gradually changed from a traditional agriculture-based livelihood to a tourism-based livelihood. The marital radius of the Mosuo people has also extended with the expansion of the scope of interactions. The previous custom of 'walking marriage' has gradually transitioned to the nuclear family model, and the traditional matriarchal extended family has also been slowly reduced to a smaller family size. The division of labor of the family members has been adjusted accordingly. Through the study of the Mosuo marriage and family changes under the tourism industry, not only can we find the path of change of the local traditional culture, but also can make some thoughts on the impact of the current tourism development in ethnic areas.

Excitation functions of72Ge(p,xn)72,71As reactions from threshold up to 45 MeV for production of the non-standard positron emitter 72As

Nuclear reaction cross sections for the formation of 72As and 71As in proton-induced reactions on enriched 72Ge targets were measured up to 45 MeV utilizing three different cyclotrons at the Forschungszentrum Jülich. The stacked-thin sample activation technique in combination with high-resolution γ-ray spectrometry was used. The major γ-ray peaks of 72As and 71As formed via the 72Ge(p,n)72As and 72Ge(p,2n)71As reactions, respectively, were analyzed. The incident proton energy and flux on a foil were determined using several monitor reactions. Based on integrated counts, irradiation data and the nuclear decay data, the reaction cross sections were measured. All data describe the first measurements. Theoretical nuclear model calculations were then carried out by using the codes TALYS 1.96, EMPIRE 3.2 and ALICE-IPPE. A very good agreement between the measured data and calculated values was found. The new data enabled us to calculate the thick target yields and estimate the radionuclidic impurities for a given energy range. Over the optimum energy range Ep = 14 → 7 MeV, the calculated thick target yield of 72As amounts to 272 MBq/μAh with no 71As impurity at all. The 72Ge(p,n)72As reaction on the enriched 72Ge is thus very suitable for clinical scale production of 72As at a medical cyclotron.

Nuclear model calculation of yield for 64Cu radionuclide produced in 65Cu(α, x)64Cu reaction at ≈ 10–40 MeV

This paper used theoretical nuclear model calculations to estimate the production yield of medically important 64Cu radionuclide produced in the interaction of α-projectile with 65Cu-target at ≈10–40 MeV. Production cross-sections were predicted using TALYS-1.9(G), EMPIRE 3.2, and ALICE/ASH reaction model codes. Generally, the TALYS-1.95(G) predicted and measured cross-sections to produce 64Cu radionuclide are in very good agreement. Further, the statistical analysis of Pearson's coefficient confirmed strong positive correlations between TALYS-1.95(G) predictions and most experimentally measured production cross-sections. The calculated thick target yields of 64Cu radionuclide showed that 65Cu(α, x)64Cu reaction resulted in a maximum yield of up to ≈ 1423 MBq/μAh at ≈ 30 MeV. Furthermore, analyzes of isotopic impurities produced during 64Cu production could only give rise to the significant yield of 66Cu impurity as much as ≈ 1988 MBq/μAh, which complicated the process of radiochemistry; however, the relatively short half-life of 66Cu isotopic impurity could only demand a waiting time of about 1.5 h to decrease its contribution to a negligible level.The yield obtained for the 64Cu radionuclide via the 65Cu(α, x)64Cu route is significant. It validates the viability of this production route and underscores its potential as a promising option for the optimized supply of 64Cu in radiopharmaceutical applications. While further investigations on quality validating parameters are necessary, the potential of the 65Cu(α, x)64Cu production route cannot be overstated.

A deep learning-based toolkit for 3D nuclei segmentation and quantitative analysis in cellular and tissue context.

We present a new set of computational tools that enable accurate and widely applicable 3D segmentation of nuclei in various 3D digital organs. We have developed an approach for ground truth generation and iterative training of 3D nuclear segmentation models, which we applied to popular CellPose, PlantSeg and StarDist algorithms. We provide two high-quality models trained on plant nuclei that enable 3D segmentation of nuclei in datasets obtained from fixed or live samples, acquired from different plant and animal tissues, and stained with various nuclear stains or fluorescent protein-based nuclear reporters. We also share a diverse high-quality training dataset of about 10,000 nuclei. Furthermore, we advanced the MorphoGraphX analysis and visualization software by, among other things, providing a method for linking 3D segmented nuclei to their surrounding cells in 3D digital organs. We found that the nuclear-to-cell volume ratio varies between different ovule tissues and during the development of a tissue. Finally, we extended the PlantSeg 3D segmentation pipeline with a proofreading tool that uses 3D segmented nuclei as seeds to correct cell segmentation errors in difficult-to-segment tissues.

A nonlinear high-order transformations-based method for high-order tensor completion

The high-order tensor nuclear norm model (HTNN) has recently shown promising results in tensor completion problems. The HTNN-based approaches rely on the low-rank structure of tensor slices during reversible transformations. However, under reversible transformations, the low-rank configuration within the slice-wise modality of the tensor’s structure is not markedly pronounced. In order to more effectively describe the low-rank characteristics, we propose a model based on the nonlinear high-order transform-based tensor nuclear norm (NHTNN). Specifically, our framework consists of a linearly semi-orthogonal transformation along the high-dimensional modality and an element-wise nonlinear transformation. We introduce a model for tensor completion, grounded in the suggested measure of tensor low-rank, i.e., NHTNN. Utilizing this non-convex nonlinear model, we formulate a proximal alternating minimization (PAM) algorithm, establishing its convergence through a rigorous proof. In experiments on datasets such as hyperspectral videos (HSVs) and color videos (CVs), our approach demonstrates superior quantitative numerical results and qualitative visual effects compared to cutting-edge tensor completion techniques.

P-798 A feasible clinical model to generate genotyped oocytes for infertile women

Abstract Study question Is it possible to generate genotyped oocytes by utilizing accessible somatic cells in a somatic cell nuclear transfer model? Summary answer Genotyped oocytes generated through haploidization of endometrial somatic cells exhibited reliably completed embryo development and yielded healthy offspring. What is known already The generation of genotyped oocytes through neogametogensis or somatic cell nuclear transfer (SCNT) would be the ultimate solution to treat female infertility due to primary ovarian insufficiency or agonadism. Among the various approaches, somatic cell haploidization appears more feasible (Lee, et al 2022). Unfortunately, this approach has only been successful in a murine model using cumulus cells. However, this donor cell type is not ideal when translated into clinical setting, due to the absence of cumulus cells in patients who are void of oocytes, which arguably is the patient population that would potentially benefit the most from this technique. Study design, size, duration In a mouse SCNT model, endometrial stromal cells (EMSCs) were injected into enucleated oocytes. Cumulus cells (CCs) were used as another source of nuclear donor. Intact MII oocytes were used as control. Post-SCNT oocytes and controls were inseminated by spermatozoa from B6-EGFP mice to monitor paternal genome presence through embryo development and offspring. Embryos were cultured in a time-lapse microscope. To prove gamete competence, blastocysts were transferred into pseudo-pregnant recipients and offspring health was assessed. Participants/materials, setting, methods Endometrial stromal cells were cultured for 4 days and exposed to aphidicolin overnight to synchronize at G1 phase of cell cycle. Cumulus cells were collected after denudation. Oocytes from B6D2F1 mice were enucleated under polarized light microscope. SCNT was performed with CCs or EMSCs by lipofectamine-mediate fusion. Oocytes were inseminated with spermatozoa from GFP-positive transgenic mice. Embryos morphokinesis were assessed by a time-lapse system. Blastocysts were transferred into 2.5-dpc surrogate CD1 mice. Main results and the role of chance Control oocytes(n = 75) fertilized at 93.3%(70/75) and progressed to 2-cell stage at 93.3%(70/75), 8-cell at 93.3%(70/75) and blastocyst at 89.3%(67/75). The control embryos started syngamy at 14.4±1h, reaching the 4-cell stage at 37.3±3h and blastulation at 80.6±8h. A total of 484 oocytes were enucleated, 470(97.1%) survived and underwent SCNT using CCs(n = 85) or EMSCs(n = 385). Fusion rate was 95.5% for CC with a haploidization rate of 70.9%(56/79) that led to a fertilization rate of 64.3%(36/56). The CC cohort developed to 2-cell, 8-cell, and morula at 47.4%, 35.4%, and 22.8%, with a delay in development at syngamy at 19.0±8h(P<0.0001). In the EMSC cohort, fusion rate was 96.0%(361/376). Haploidization rate was 65.4%(236/361), comparable to the CC cohort(P = 0.35). Fertilization was lower in the EMSC cohort at 47.0%(P<0.01) compared to the CC cohort. Subsequently, EMSC cohort yielded similar cleavage rates to 2-cell stage at 30.7%, 8-cell stage at 29.4%, and morula stage at 28.5%. The blastocyst rate was higher in the EMSC cohort at 28.0%(P<0.05). The EMSC cohort yielded similar developmental timing comparing to controls from pronuclear appearance to 4-cell cleavage but a delay manifested afterward at 37.3±3h(P<0.0001). In the EMSC cohort, 42 blastocysts were transferred, yielding 3 healthy pups(2 male,1 female). Limitations, reasons for caution While we generated consistent haploidization and satisfactory fertilization, full pre-implantation development remained low. Even more limited was the live birth rate, which probably related to subtle factors such as an imprinting issue due to insufficient reprogramming of the somatic cell donor. Wider implications of the findings The SCNT model described to generate genotyped oocytes, although still with limited efficiency, represents a feasible reproductive option for women with agonadism and compromised ovarian reserve. This model is still a better approach to complete neogametogenesis. Trial registration number not applicable

A study on the impact of using a subchannel resolution for modeling of large break loss of coolant accidents

The nuclear industry is investigating the feasibility of transitioning from 18- to 24-month fuel cycles because of the positive impact it would have on the operational costs for the current fleet of light-water reactors. A challenge to making this change is the increased risk of fuel fragmentation, relocation, and dispersal (FFRD) due to the known potential for ceramic fuel to pulverize into fine particles at the higher discharge burnups. Previous work has been performed by the Nuclear Energy Advanced Modeling and Simulation program to assess FFRD risk in high-burnup cores using the BISON fuel performance code and a coarse mesh thermal hydraulics (T/H) solution for a loss-of-coolant accident (LOCA) using the TRACE system T/H code. Because of the importance of the T/H solution for FFRD assessment, this study seeks to investigate the impact of using higher-fidelity subchannel techniques for modeling of the LOCA transient. CTF was used to model a subregion of a high-burnup core that was depleted by the Virtual Environment for Reactor Applications (VERA) multiphysics core simulator. Both coarse-mesh and pin-resolved models were created in CTF, and a consistent coarse-mesh TRACE model was also developed to allow for benchmarking the code results. A large-break loss-of-coolant accident (LBLOCA) reflood transient was simulated using these three models, and results were compared. Results showed some consistent differences between the CTF and TRACE coarse models, including a higher peak cladding temperature (PCT) prediction in CTF and later quenching in CTF; however, the transient clad temperature behavior was similar, and these differences are likely due to post-critical heat flux heat transfer modeling differences and minimum film boiling temperature model differences. The pin-resolved results indicate that the PCT in the lumped model is often under-predicted by as much as 70 °C and that PCT occurs at a different location than the high-power pin in the assembly. The lumped model predicts a difference of 10 °C or less between the average and hot pins in the assembly, whereas the pin-resolved model predicts a range of over 100 °C. These results indicate that higher-fidelity T/H results may have an impact on predicted core behavior during LOCA, which may be important to consider when assessing FFRD risk.

Multipoint kinetics model with power reactivity defect for the axial offset control in the VVER-1200 nuclear reactor during the load following mode of operation

This article proposes the multipoint kinetics model consisting with different number of point kinetics model (two points, four points, six points, eight points, ten points) in the axial direction for the VVER-1200 nuclear reactor. Each node is coupled with others through the coupling coefficients determined from the diffusion approach. For more precise description of the dynamical modes of the reactor operation, the proposed model integrates the power reactivity feedback derived from temperature reactivity coefficients and Mann’s thermal hydraulic model which assumes one fuel node adjacent to two coolant nodes. On the model with four axial points, additionally was tested the influence of the different number of delayed neutrons groups on the accuracy results and model running time during the load-following mode of operation. Moreover, the novel model of the control rods is introduced, utilizing a combination of sign functions to sequentially influence all nodes during insertion or withdrawal. The computational results show that the accuracy of the proposed model is satisfactory, and general assumptions about transients align with their physical definitions. This research contributes to the advancement of the point-like nuclear reactor modeling for improvement of the automatic power controller synthesis.

Nuclear deformation effects in the spectra of highly charged ions

With the increasing precision of spectroscopic measurements, there is a growing demand for more accurate theoretical predictions, which requires the estimation of various higher-order effects, such as the nuclear deformation effect. Here, we present the results for nuclear deformation correction for the widest range of nuclei. The effects are investigated in terms of electronic transition energies, g factors, and hyperfine splitting constants, by implementing the deformed Fermi nuclear model to the Dirac equation. Based on the improved methodology and appropriate data classification, we present the results for over 1100 nuclei on figures, showing the general trends and anomalies. Moreover, it can serve as a simple tool providing estimations for specific planned research. In addition, we examine the connections and significance of deformation effects in the search of new physics with singly charged ions. Published by the American Physical Society 2024

Nuclear Magnetic Resonance Logging-Based Permeability Classification Modeling for Tight Sandstone Reservoirs

The Upper Paleozoic tight sandstone reservoirs on the eastern margin of the Ordos Basin exhibit strong heterogeneity and complex pore structures, leading to poor correlation between porosity and permeability and insufficient accuracy in permeability calculations to meet the requirements of reservoir fine evaluation. Therefore, a new method for high-precision permeability calculation based on flow zone index (FZI) reservoir classification is proposed. This method determines the number of reservoir classifications based on the characteristics of the FZI normal probability distribution plot and establishes FZI division criteria for reservoir types. Classified reservoirs exhibit similar flow characteristics, significantly improving the correlation between permeability and porosity. Based on nuclear magnetic resonance (NMR) combined with mercury injection capillary pressure (MICP) experiments, a modeling method for calculating the flow zone index based on the geometric mean of NMR T2 is proposed. This method realizes continuous calculation of FZI based on NMR logging, reservoir classification, and permeability for the entire wellbore, thereby constructing a new permeability prediction method for tight sandstone reservoirs based on NMR logging and FZI classification. Actual application results demonstrate that the permeability calculated using NMR logging is in high agreement with the permeability analyzed from core data, with an average relative error of 45.8%, proving the effectiveness of the proposed method in this study.

Nuclear clustering-manifestations of non-uniformity in nuclei.

Well-developed [Formula: see text] clusters are known to exist in light [Formula: see text] nuclei, and their properties are reasonably well described with modern nuclear structure theories. However, 'modestly' developed clusters in medium to heavy nuclei remain little understood, both theoretically and experimentally. Extension of the focus to include modestly developed clusters leads us to a concept of 'generalized clusters' and 'cluster ubiquitousness'. The former includes clusters more weakly bound than an [Formula: see text] cluster, such as deuteron, triton and [Formula: see text], and even clusters partially broken owing to nuclear medium effects. The latter means the existence of clusters in any nuclei, where cluster development was not previously discussed. Effects of the tensor and the spin-orbit interactions on the coexistence of clusters with independent nucleons are discussed using recent nuclear theoretical models. A mixture of the clusters with shell-like components plays an essential role in the synthesis of elements in the universe and the origin of life, together with an [Formula: see text] decay. It is also pointed out that clustering in heavy nuclei may accelerate fission and fusion processes. Future experimental plans using cluster knockout reactions, which have the potential to extract information of 'generalized clusters' in a variety of nuclei including stable and unstable nuclei, are also discussed. This article is part of the theme issue 'The liminal position of Nuclear Physics: from hadrons to neutron stars'.