Nuclear Compressibility Research Articles

PRSS50-mediated inhibition of MKP3/ERK signaling is crucial for meiotic progression and sperm quality.

Serine protease 50 (PRSS50/TSP50) is highly expressed in spermatocytes. Our study investigated its role in testicular development and spermatogenesis. Initially, PRSS50 knockdown was observed to impair DNA synthesis in spermatocytes. To further explore this, we generated PRSS50 knockout ( Prss50 -/- ) mice ( Mus musculus), which exhibited abnormal spermatid nuclear compression and reduced male fertility. Furthermore, dysplastic seminiferous tubules and decreased sex hormones were observed in 4-week-old Prss50 -/- mice, accompanied by meiotic progression defects and increased apoptosis of spermatogenic cells. Mechanistic analysis indicated that PRSS50 deletion resulted in increased phosphorylation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and elevated levels of MAP kinase phosphatase 3 (MKP3), a specific ERK antagonist, potentially accounting for testicular dysplasia in adolescent Prss50 -/- mice. Taken together, these findings suggest that PRSS50 plays an important role in testicular development and spermatogenesis, with the MKP3/ERK signaling pathway playing a significant role in this process.

Phase diagram determination at fivefold nuclear compression

In the standard model of particle physics, the strong force is characterized by the theory of quantum chromodynamics (QCD). It is commonly understood from QCD properties that hadrons, at sufficiently high temperatures or densities, melt into their constituent quarks, thereby undergoing a deconfinement transition to a new phase of quarks and gluons, often referred to as quark matter or quark-gluon plasma (QGP) [1,2]. Although QGP has been observed in relativistic heavy-ion collisions [3,4], uncertainties remain about when the onset of deconfinement occurs. After comparing simulations from a reliable hadron and quark relativistic transport model with recent data from the STAR experiment, we determined that the onset of the hadron-quark phase transition occurs at about five times nuclear compression, corresponding to temperature T∼ 112 MeV and baryon chemical potential μB∼ 586 MeV, in the nuclear matter phase diagram. This discovery has significant implications for the studies of both the early and present universe [5], including the fraction of dark matter formed in the early universe [6–8] and the structure and dynamics of neutron stars and their mergers [9].

Mechanopathology of biofilm-like Mycobacterium tuberculosis cords

Mycobacterium tuberculosis (Mtb) cultured axenically without detergent forms biofilm-like cords, a clinical identifier of virulence. In lung-on-chip (LoC) and mouse models, cords in alveolar cells contribute to suppression of innate immune signaling via nuclear compression. Thereafter, extracellular cords cause contact-dependent phagocyte death but grow intercellularly between epithelial cells. The absence of these mechanopathological mechanisms explains the greater proportion of alveolar lesions with increased immune infiltration and dissemination defects in cording-deficient Mtb infections. Compression of Mtb lipid monolayers induces a phase transition that enables mechanical energy storage. Agent-based simulations demonstrate that the increased energy storage capacity is sufficient for the formation of cords that maintain structural integrity despite mechanical perturbation. Bacteria in cords remain translationally active despite antibiotic exposure and regrow rapidly upon cessation of treatment. This study provides a conceptual framework for the biophysics and function in tuberculosis infection and therapy of cord architectures independent of mechanisms ascribed to single bacteria.

Nuclear compression regulates YAP spatiotemporal fluctuations in living cells

Yes-associated protein (YAP) is a key mechanotransduction protein in diverse physiological and pathological processes; however, a ubiquitous YAP activity regulatory mechanism in living cells has remained elusive. Here, we show that YAP nuclear translocation is highly dynamic during cell movement and is driven by nuclear compression arising from cell contractile work. We resolve the mechanistic role of cytoskeletal contractility in nuclear compression by manipulation of nuclear mechanics. Disrupting the linker of nucleoskeleton and cytoskeleton complex reduces nuclear compression for a given contractility and correspondingly decreases YAP localization. Conversely, decreasing nuclear stiffness via silencing of lamin A/C increases nuclear compression and YAP nuclear localization. Finally, using osmotic pressure, we demonstrated that nuclear compression even without active myosin or filamentous actin regulates YAP localization. The relationship between nuclear compression and YAP localization captures a universal mechanism for YAP regulation with broad implications in health and biology.

Excitation of the delta-resonance in compressed super heavy neutron-rich doubly magic [formula omitted] nucleus

By using constrained spherical Hartree-Fock approximation (CSHF), nuclear system of the super-heavy spherical U126310bh184 nucleus is investigated. CSHF is applied to no-core shell model, with an effective baryon-baryon interaction. Physical properties are affected by delta excitation under compression. It is shown when the △ resonances have occurred, the nucleus becomes more bound. Also, it can be seen that as the compression is continuous, the formation of △ increases. Under compression, the most of increment in energy of the system is gone to △-mass formation. Therefore, this appears to play a role in nuclear compression in subthreshold pion-production in heavy ions collisions. When the △ degree of freedom is created, reduced compressibility has occurred. In a ground state without nuclear compression, it is seen that the U126310bh184 nucleus is formed from the △ particles as the basic component besides nucleons. Also, there is a radial density distribution of the △ particles at the ground state for the U126310bh184 nucleus. If the nucleus was compressed to twenty-four of the ordinary density, then the △ particle would have been sharply increased to about 14.2% of all particles in the nucleus. The single particle spectra are studied under nuclear compression too. An excellent agreement was happened between the calculations and the shell model for the low levels of the single particle energies. Finally, there is a excellent consistency between the effective Hamiltonian and phenomenological shell model results for the lower single particle energy levels.

Double strangeness Ξ− production as a probe of nuclear equation of state at high densities

Double strangeness Ξ− production in Au+Au collisions at 2, 4, and 6 GeV/nucleon incident beam energies is studied with the pure hadron cascade version of a multi-phase transport model. It is found that due to larger nuclear compression, the model with the soft equation of state (EoS) gives larger yields of both single strangeness (K+ and Λ+Σ0) and double strangeness Ξ−. The sensitivity of the double strangeness Ξ− to the EoS is evidently larger than that of K+ or Λ+Σ0 since the phase-space distribution of produced Ξ− is more compact compared to those of the single strangeness. The larger sensitivity of the yields ratio of Ξ− to the EoS from heavy and light systems is kept compared to that of the single strangeness. The study of Ξ− production in relativistic heavy-ion collisions provides an alternative for the ongoing heavy-ion collision program at facilities worldwide for identifying the EoS at high densities, which is relevant to the investigation of the phase boundary and onset of deconfinement of dense nuclear matter.

Spatial distribution of lamin A/C determines nuclear stiffness and stress-mediated deformation.

ABSTRACTWhile diverse cellular components have been identified as mechanotransduction elements, the deformation of the nucleus itself is a critical mechanosensory mechanism, implying that nuclear stiffness is essential in determining responses to intracellular and extracellular stresses. Although the nuclear membrane protein lamin A/C is known to contribute to nuclear stiffness, bulk moduli of nuclei have not been reported for various levels of lamin A/C. Here, we measure the nuclear bulk moduli as a function of lamin A/C expression and applied osmotic stress, revealing a linear dependence within the range of 2–4 MPa. We also find that the nuclear compression is anisotropic, with the vertical axis of the nucleus being more compliant than the minor and major axes in the substrate plane. We then related the spatial distribution of lamin A/C with submicron 3D nuclear envelope deformation, revealing that local areas of the nuclear envelope with higher density of lamin A/C have correspondingly lower local deformations. These findings describe the complex dispersion of nuclear deformations as a function of lamin A/C expression and distribution, implicating a lamin A/C role in mechanotransduction.This article has an associated First Person interview with the first author of the paper.

Tissue folding at the organ–meristem boundary results in nuclear compression and chromatin compaction

Artificial mechanical perturbations affect chromatin in animal cells in culture. Whether this is also relevant to growing tissues in living organisms remains debated. In plants, aerial organ emergence occurs through localized outgrowth at the periphery of the shoot apical meristem, which also contains a stem cell niche. Interestingly, organ outgrowth has been proposed to generate compression in the saddle-shaped organ-meristem boundary domain. Yet whether such growth-induced mechanical stress affects chromatin in plant tissues is unknown. Here, by imaging the nuclear envelope in vivo over time and quantifying nucleus deformation, we demonstrate the presence of active nuclear compression in that domain. We developed a quantitative pipeline amenable to identifying a subset of very deformed nuclei deep in the boundary and in which nuclei become gradually narrower and more elongated as the cell contracts transversely. In this domain, we find that the number of chromocenters is reduced, as shown by chromatin staining and labeling, and that the expression of linker histone H1.3 is induced. As further evidence of the role of forces on chromatin changes, artificial compression with a MicroVice could induce the ectopic expression of H1.3 in the rest of the meristem. Furthermore, while the methylation status of chromatin was correlated with nucleus deformation at the meristem boundary, such correlation was lost in the h1.3 mutant. Altogether, we reveal that organogenesis in plants generates compression that is able to have global effects on chromatin in individual cells.

Designing 3D-nanosubstrates mimicking biological cell growth: pitfalls of using 2D substrates in the evaluation of anticancer efficiency.

Designing nano-substrates (NS) that support three-dimensional (3D) cell growth using physico-chemical interventions mimicking the cellular microenvironment is highly challenging. Here we report NS that assist 3D cell development (3D NS) using multi-components on a glass substrate (2D GS), which mimics the ex vivo tissue microenvironment and promotes 3D cell growth superior to conventional 2D cell culturing methodologies. 3D NS were chemically fabricated by linking the combination of advanced materials imparting different physico-chemical traits, for example, multiwalled carbon nanotubes (CNT), graphene (G), bovine serum albumin (BSA), and iron oxide magnetic nanoparticles (MNP). We compared cell-substrate interactions resulting in cellular morphological changes, influence on the cell circularity index (CI), nuclear-cytoplasmic ratios (N/C), and nuclear compression or derangements using human colorectal carcinoma cells (HCT116) and cervical cancer (HeLa) cells. We observed the increase in N/C, extended on the 3D NS micro-environment as indicative of cellular adaptation and the transformation. HCT116 and HeLa cells on 2D GS showed an N/C ratio <0.3, and 3D NS cultured cells exhibited a higher N/C ratio (>0.5). The most significant increase in the ratio, relative to arrested cell spreading, was observed with G-3D NS. Furthermore, 3D NS were evaluated for the cell viability differentiations using the anticancer drug doxorubicin (Dox). The drug-treated cells on 3D NS demonstrated far-displaced N/C ratios compared to 2D GS. In conclusion, 3D NS systems implicate an 'in vitro to in vivo' relevance for the outcome in cell biology, cell proliferation and migration, and in anticancer drug efficacy evaluation.

Studying the parameters of the extended \u03c3-\u03c9 model for neutron star matter

In this work we study the parameters of the extended σ-ω model for neutron star matter by a Bayesian analysis of state-of-the-art multi-messenger astronomy observations, namely mass, radius and tidal deformabilities. We have considered three parameters of the model, the Landau mass mL, the nuclear compressibility K0, and the value of the symmetry energy S0, all at saturation density n0. As a result, we are able to estimate the best values of the Landau mass of mL ≈ 0.73 GeV, whereas the values of K0 and S0 fall within already known empirical values. Furthermore, for neutron stars we find the most probable value of 13 km < R1.4 < 13.5 km and the upper mass limit of Mmax ≈ 2.2 M⊙.

Experimental research on compression and collapsible characteristics of saline soil

Fine-grained saline soil is widely distributed in the western region of China. Studying compression and dissolution characteristics of salty soil can provide technical support for local engineering design. In this paper, deformation characteristics of saline soil were studied by nuclear magnetic resonance experiment, compression and dissolution test. Results showed that the compression coefficient was negatively related to the pressure and dry density. When dry density was small, e-lgp curve in the back was a straight line. As dry density growing, e-lgp curve became more and more gentle, and feature of straight line disappeared gradually. As pressure increased, compression coefficient reduced. The maximum collapsible deformation was 25kpa pressure under ρd.=1.3,1.35g/cm3 condition. As dry density added, load corresponding to the maximum amount of collapse increased. With growing of confining pressure, pore size decreased gradually. After pressure consolidation of 50, 100, 200, 300 and 500kPa, 99.85% of the pore size is distributed between 0-0.1 μm.

Measuring Changes in Electrical Impedance During Cell-Mediated Mineralization.

Background: The fundamental electrical properties of bone have been attributed to the organic collagen and the inorganic mineral component; however, contributions of individual components within bone tissue toward the measured electrical properties are not known. In our study, we investigated the electrical properties of cell-mediated mineral deposition process and compared our results with cell-free mineralization. Materials and Methods: Saos-2 cells encapsulated within gelatin methacrylate (GelMA) hydrogels were chemically stimulated in osteogenic medium for a period of 4 weeks. The morphology, composition, and mechanical properties of the mineralized constructs were characterized using bright-field imaging, scanning electron microscopy (SEM) energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy (FITR), nuclear magnetic resonance spectroscopy (NMR), micro-CT, immunostaining, and mechanical compression tests. In parallel, a custom-made device was used to measure the electrical impedance of mineralized constructs. All results were compared with cell-free GelMA hydrogels mineralized through the simulated body fluid approach. Results: Results demonstrate a decrease in the electrical impedance of deposited mineral in both cell-mineralized and cell-free mineralized samples. Conclusions: This study establishes a model system to investigate in vivo and in vitro mineralization processes.

Compressional modes in two-superfluid neutron stars with leptonic buoyancy

We investigate the compressional modes of cold neutron stars with cores consisting of superfluid neutrons, superconducting protons and normal fluid electrons and muons, and crusts that contain superfluid neutrons plus a normal fluid of (spherical) nuclei and electrons. We develop a two-fluid formalism for the core that accounts for leptonic buoyancy, and an analogous treatment for the crust. We adopt the Cowling approximation, neglecting gravitational perturbations, but include all effects of the background space-time. We introduce a phenomenological, easily-modified nuclear equation of state which contains all of the thermodynamic information required to compute the coupled fluid oscillations, with parameters that are constrained by nuclear physics and the requirement that the maximum mass of a neutron star is $\geq 2M_{\odot}$. Using four parametrizations of this equation of state with nuclear compressibilities $K=230$-$280$ MeV, we calculate the Brunt-V\"{a}is\"{a}l\"{a} frequency due to leptonic buoyancy, and find the corresponding $g$-mode frequencies and eigenfunctions. We find that the WKB approximation reproduces $g$-mode frequencies closely. We examine the dependence of $g$-mode frequencies on stellar mass, nuclear compressibility and strength of neutron-proton entrainment, and compare to previous calculations of $g$-mode frequencies due to leptonic buoyancy. We also compute the $p$-mode spectra, confirming previous findings that the two fluids behave as if uncoupled except the case of large entrainment, and show the existence of nearly resonant mode pairs which could lead to nonlinear $p$-$g$ instabilities even at zero temperature.

Development and verification of PWR-core fuel management calculation code system NECP-Bamboo: Part I Bamboo-Lattice

Abstract PWR-core fuel management calculation code system named NECP-Bamboo is designed to meet different requirements from engineering application, scientific research and nuclear force education simultaneously. In its two-dimensional lattice calculation code Bamboo-Lattice, the one-step direct heterogeneous calculation scheme based on fine-group structure is employed. A series of approximations were eliminated, including the empirical experience based nuclear depletion data library compression, the averaged fission spectrum, the equivalence resonance theory, the pin-cell homogenized lattice calculation, the combined neutron capture energy release, the linear microscopic reaction rate for burnable absorber, and etc. Numerical verification results from single fuel pin-cell, single fuel assembly, multiple assembly and two-dimensional BEAVRS whole-core calculations indicate its good accuracy.

Nucleon properties inside the compressed nuclear matter

In this work, we show the modifications of nucleon mass and nucleon radius with the help of the extended Relativistic Mean Field (RMF) model. We argue that even small departures above nuclear equilibrium density with constant nucleon mass require an energy transfer from the repulsive mean field to the quarks forming nucleon massive bags in Nuclear Matter (NM), together with the decrease in the nucleon volume. The transfer, which is proportional to pressure and absent in a standard RMF approach, provides good values for nuclear compressibility, symmetry energy and its slope. Different courses of the Equation of State (EOS), which depend on the energy transfer, are considered.

The Effect of Cadmium on the Ultrastructure and Metallothionein Levels in the Liver and Kidneys of Japanese quail

Background: The aim of this study was to use Japanese quail as an animal model to evaluate the effects of cadmium (Cd) on the ultrastructure and the activity of metallothionein (MT) in the liver and kidneys. Methods: One hundred male Japanese quails were randomly divided into two Cd and control groups in 2015. The first group received 100 ppm Cd for 60 days in their feed. The ultrastructural changes of the liver and kidneys of Japanese quails were examined by the transmission electron microscope and the concentration of MT in these organs was measured. Results: The ultrastructural alternations of the liver included distension of rough endoplasmic reticulum (RER), mitochondrial swelling and lack of cristae, nuclear chromatin compression, and margination, the increased fat vacuole and damage to intercellular bindings. The kidneys ultrastructural alterations were mitochondrial swelling and damage to the cristae, the increased number of lysosomes, nuclear chromatin compression and margination, the decreased number of microvilli, and cell death. The concentration of MT and Cd in the liver and kidneys of the Cd group was significantly higher than that of the control group (P<0.05). A positive correlation was observed between the increased concentration of Cd and MT in the liver and kidney tissues. Conclusion: The use of oral Cd caused an alternation in the ultrastructure and increased the concentration of Cd and MT in the liver and kidneys of Japanese quail.

Quantitative evaluation of the effects of nuclear compression on DNA aggregation

Quantitative evaluation of the effects of nuclear compression on DNA aggregation

Higher-order baryon number susceptibilities: Interplay between the chiral and the nuclear liquid-gas transitions

We use an improved version of the SU(3) flavour parity-doublet quark-hadron model to investigate the higher order baryon number susceptibilities near the chiral and the nuclear liquid-gas transitions. The parity-doublet model has been improved by adding higher-order interaction terms of the scalar fields in the effective mean field Lagrangian, resulting in a much-improved description of nuclear ground-state properties, in particular the nuclear compressibility. The resulting phase diagram of the model agrees qualitatively with expectations from lattice QCD, i.e., it shows a crossover at zero net baryo-chemical potential and a critical point at finite density. Using this model, we investigate the dependence of the higher-order baryon number susceptibilities as function of temperature and chemical potential. We observe a strong interplay between the chiral and liquid-gas transition at intermediate baryo chemical potentials. Due to this interplay between the chiral and the nuclear liquid-gas transitions, the experimentally measured cumulants of the net baryon number may show very different beam energy dependence, subject to the actual freeze-out temperature.

Achieving high baryon densities in the fragmentation regions in heavy ion collisions at top RHIC energy

Heavy ion collisions at extremely high energy, such as the top energy at RHIC, exhibit the property of transparency where there is a clear separation between the almost net-baryon-free central rapidity region and the net-baryon-rich fragmentation region. We calculate the net-baryon rapidity loss and the nuclear excitation energy using the energy-momentum tensor obtained from the McLerran-Venugopalan model. Nuclear compression during the collision is further estimated using a simple space-time picture. The results show that extremely high baryon densities, about twenty times larger than the normal nuclear density, can be achieved in the fragmentation regions.

Microscopic dynamical description of proton-induced fission with the constrained molecular dynamics model

The microscopic description of nuclear fission still remains a topic of intense basic research. Un- derstanding nuclear fission, apart from a theoretical point of view, is of practical importance for energy production and the transmutation of nuclear waste. In nuclear astrophysics, fission sets the upper limit to the nucleosynthesis of heavy elements via the r-process. In this work we initiated a systematic study of intermediate energy proton-induced fission using the Constrained Molecu- lar Dynamics (CoMD) code. The CoMD code implements an effective interaction with a nuclear matter compressibility of K=200 (soft EOS) with several forms of the density dependence of the nucleon-nucleon symmetry potential. Moreover, a constraint is imposed in the phase-space occu- pation for each nucleon restoring the Pauli principle at each time step of the collision. A proper choice of the surface parameter of the effective interaction has been made to describe fission. In this work, we present results of fission calculations for proton-induced reactions on : a) 232 Th at 27 and 63 MeV, b) 235 U at 10, 30, 60 and 100 MeV, and c) 238 U at 100 and 660 MeV. The calculated observables include fission-fragment mass distributions, total fission energies, neutron multiplicities and fission times. These observables are compared to available experimental data. We show that the microscopic CoMD code is able to describe the complicated many-body dynamics of the fission process at intermediate and high energy and give a reasonable estimate of the fission time scale. Sensitivity of the results to the density dependence of the nucleon symmetry potential (and, thus, the nuclear symmetry energy) is found. Further improvements of the code are necessary to achieve a satisfactory description of low energy fission in which shell effects play a dominant role.