Saturation Density Research Articles

Glassy quantum nuclear pasta in neutron star crusts

Nuclear pasta is an exotic form of nuclear matter that occurs in the crust of neutron stars below saturation density. Various exotic nuclear structures with cylindrical, planar, and more complicated geometries evolve from the Coulomb lattice of nuclei immersed in a fluid of neutrons. Such structures in the crust should not only affect how a neutron star cools and rotates but also the height of the ``mountains'' that the crust can sustain---potentially detectable as persistent sources of gravitational waves. By performing a large set of quantum calculations the authors show that the energy landscape of nuclear pasta consists of multiple local minima with very similar energies. Hence, at the characteristic temperatures nuclear pasta becomes a self-organized glassy amorphous solid similar to soft-matter systems found on Earth.

Multi-fidelity progressive damage simulation of notched composite laminates with various ply thicknesses

In this study, a multi-fidelity fracture simulation scheme of composite laminates that accomplishes a seamless transition between medium- and high-fidelity crack models, namely, smeared crack models (SCMs) and discrete crack models (DCMs), is developed. The proposed scheme is based on the adaptive discrete-smeared crack (A-DiSC) method and a theoretical model for saturated crack density. The A-DiSC method first employs a DCM to model the transverse cracks in the laminates. If the crack density of each ply reaches the saturation value calculated using the theoretical model, the DCM is converted to an SCM. At this point, some cracks that are longer than a certain critical length remain explicitly modeled by the DCM, as they can significantly affect the subsequent path to final failure. By combining the two models, this method reduces the computational cost while preserving a sufficient prediction accuracy particularly in the case with numerous noncritical cracks up to failure. A simulation of the open-hole tensile test of composite laminates with various ply thicknesses was performed to verify the prediction accuracy of the developed scheme, and the predicted results were compared with the experimental results.

Gluon and valence quark distributions for the pion and kaon in nuclear matter

In this paper we study the gluon and valence quark distributions in the pion and kaon in nuclear medium for various nuclear densities as well as in vacuum within the Nambu--Jona-Lasinio (NJL) model with the help of the proper-time regularization scheme which simulates a confinement of QCD. The nuclear medium effect is also determined in the same model for the symmetric nuclear matter. We then analyze the gluon and valence quark distributions for the bound pion and kaon in symmetric nuclear matter as well as those in vacuum. We find that the valence quark and gluon distributions in vacuum have relatively good agreements with the experimental data, the lattice QCD simulations, and the JAM Monte-Carlo (MC) global fit QCD analysis. Evolving to the higher factorization scale $Q=4\text{ }\text{ }\mathrm{GeV}$, the in-medium gluon and valence-quark distributions of the pion for various nuclear densities are turned out to be almost unchanged in comparison to the vacuum cases. On the contrary, for the kaon, they increase significantly with respect to the densities. Finally, we find that the vacuum gluon distribution for the kaon is smaller than that for the pion, which is consistent with other theoretical predictions. This feature holds for the in-medium gluon distribution in the nuclear density up to the saturation density.

Characterization of the Dissolution of Water Microdroplets in Oil

Water in oil emulsions have a wide range of applications from chemical technology to microfluidics, where the stability of water droplets is of paramount importance. Here, using an accessible and easily reproducible experimental setup we describe and characterize the dissolution of water in oil, which renders nanoliter-sized droplets unstable, resulting in their shrinkage and disappearance in a time scale of hours. This process has applicability in creating miniature reactors for crystallization. We test multiple oils and their combinations with surfactants exhibiting widely different rates of dissolution. We derived simple analytical equations to determine the product of the diffusion coefficient and the relative saturation density of water in oil from the measured dissolution data. By measuring the moisture content of mineral and silicone oils with Karl Fischer titration before and after saturating them with water, we calculated the diffusion coefficient of water in these two oils.

Comparison of the vitality tests used in the dental clinical practice and histological analysis of the dental pulp.

In dentistry, indirect diagnostic methods such as electrical sensibility testing and pulse oximetry are used to assess the status of the pulp. Our study aimed to determine the correlation between hemoglobin oxygen saturation and vascular volume density (Vvasc). We also wanted to examine an electrical sensibility test and the volume density of myelinated nerve fibers (Vnerv). Twenty-six intact permanent premolars were included in the study. For histological analysis, the pulp tissue was stained with hematoxylin-eosin and immunohistochemically for von Willebrand factor and S100 to detect blood vessels and myelinated nerve fibers, respectively. The stereological analysis was used to determine the Vvasc and Vnerv. Statistical analysis was done using the Pearson correlation test and Welch’s ANOVA test. Histological analysis showed that the pulp tissue was strongly vascularized and innervated. A significant positive correlation was found between Vvasc and hemoglobin oxygen saturation levels (p = 0.030). A significant negative correlation was found between Vnerv and the lowest electrical voltage that patient felt (p = 0.033). According to the maturity of the dental apex, teeth were divided into a group with open (n = 6, OA group) and closed apex (n = 20, CA group). We found that pulps in the CA group had higher Vnerv than the OA group (p = 0.037). In contrast, there were no significant differences in Vvasc of the pulp tissue (p = 0.059), oxygen saturation (p = 0.907), or electrical voltage (p = 0.113) between both groups. We can conclude that the measurement of pulse oximetry and electrical sensibility test reflects the morphology of healthy pulp tissue independently of the maturity of the dental apex.

Fluctuation of Satellite Charging in the Low Earth Orbit Regime due to Interaction with Ionospheric Plasma

Low Earth-orbiting satellites will always interact with the ionospheric plasma, leading to disruption of satellite operations, depending on the impact of the interaction. Under normal circumstances (without interference), the magnitude of the fluctuation in satellite charging is less than 5V (negative). Any disturbance from charged particles will cause the satellite to experience a more drastic voltage drop of the order of a few hundred volts (negative). The identification of fluctuations in satellite charging is carried out by reviewing the space conditions around the satellite, characterized by several parameters such as density, energy, and plasma temperature, as well as the saturation density of the satellite. To strengthen the analysis, this study deepens the flux changes with an energy of the order of MeV along the satellite orbit. The results of the study show that several low-earth orbit satellites experience a fairly high saturation density, which is correlated with fluctuations in electron flux in some regions traversed by the satellite, such as the polar and the SAA regions. The results confirm that the two regions could be a danger zone for both polar and equatorial satellites.

Predicting the phase equilibria of binary mixtures containing carbon dioxide + n-alkanols from a quadrupolar SAFT-VR approach

The vapor–liquid equilibria of binary mixtures containing carbon dioxide + n-alkanols is studied in the framework of the statistical associating fluid theory for potentials of variable range (SAFT-VR). The effect of the quadrupole moment of carbon dioxide on the phase equilibria is considered into the original SAFT-VR approach by incorporating an additional contribution to the Helmholtz free energy due to quadrupole–quadrupole interactions. The carbon dioxide is modeled as two spherical segments tangentially bonded with an axial quadrupolar moment. The n-alkanol molecules are represented as chains of spherical monomer segments with three associating sites to describe the hydrogen bonding interactions between the molecules. The association effects are taken into consideration by using the first-order thermodynamic perturbation theory of Wertheim. The attractive interactions between monomer segments and site-site associative interactions have been accounted for by using a square-well intermolecular potential. The pure component parameters for carbon dioxide and n-alkanols (from methanol to 1-decanol) are obtained by fitting the SAFT-VR approach to experimental saturated liquid density and vapor pressure. These optimized parameters are used to determine the vapor–liquid equilibria of the mixtures. The pressure-composition and density-composition projections predicted by SAFT-VR for the carbon dioxide + n-alkanols are in good agreement with the experimental data. A significant improvement in the description of the vapor–liquid equilibria of binary mixtures containing carbon dioxide + n-alkanols is obtained with the quadrupolar contribution compared with the results obtained from the original SAFT-VR. The optimized molecular parameters are rescaled in order to determine critical lines and the types of phase behavior. The critical lines and critical points are predicted by the original SAFT-VR approach and the quadrupolar version of the SAFT-VR in good agreement with experimental data. The inclusion of the quadrupolar interactions, present in the carbon dioxide, avoids the treatment of these interactions in an effective way via the square-well potential of variable range. The results of the present work are useful for further exploration of adsorption-extraction of n-alkanols in supercritical fluids.

Appearance of a peak in the symmetry energy at N=126 for the Pb isotopic chain within the relativistic energy density functional approach

The newly derived relativistic energy density functional [\textcolor{blue}{ Phys. Rev. C \textbf{103}, 024305 (2021)}], which stems from the effective field theory motivated relativistic mean-field (E-RMF) is employed to establish the appearance of peak/kink in the symmetry energy over the isotopic chain of Pb-nuclei. The coherent density fluctuation model parametrization procedure for finite nuclei is adopted here to obtain the relativistic energy density functional at local density. The relativistic energy density functional from E-RMFT takes precedence over the Br\"uckner energy density functional as it accurately predicts the empirical saturation density and binding energy per nucleon $E/A$, so-called 'Coester Band Problem'. Interestingly, using the relativistic energy density functional, it is possible to predict the peak at $N=126$ for recently developed G3 and widely used NL3 parameter sets, which is not observed for Br\"uckener's functional in-spite of using the E-RMF density. From the present analysis, the newly fitted energy density functional is found to be minutely sensitive to the choice of the parameter sets employed.

Recovery of milk whey proteins by foam separation

Milk whey proteins recovery was conducted with foam separation. Experiments were conducted by batch mode in pH 4–8. The separation rate was evaluated by the rate constant of the first-order kinetic equation. Both recovery efficiency and separation rate were highest at pH 7. Overall equilibrium adsorption constant, K, and saturated adsorption density, Xs, were determined from a proposed estimating method using data obtained in batch mode. At pH 7, K and Xs were determined using the data obtained in continuous mode. K and Xs determined by both operation modes were agreed well. Adsorption parameters of the major proteins in milk whey (bovine serum albumin (BSA), α-lactalbumin (LA), and β-lactoglobulin (LG)) were estimated by the proposed estimating method in pH 4–7. Xs is largest at pH 5 and the K of LG over pH 5 was larger, which suggested that LG was the most hydrophobic species among them.

Pioneering the Equation of State of Dense Nuclear Matter with Strange Particles Emitted in Heavy-Ion Collisions: The KaoS Experiment at GSI

High-energy heavy-ion collisions offer the unique possibility to study fundamental properties of nuclear matter in the laboratory, which are relevant for our understanding of the structure of compact stellar objects and the dynamics of neutron star mergers. Of particular interest are the nuclear matter equation of state (EOS), the in-medium modifications of hadrons and the degrees of freedom of matter at high densities and temperatures. Pioneering experiments exploring the EOS for symmetric matter were performed at the SIS18 accelerator of GSI, measuring, as function of beam energy, the collective flow of protons and of light fragments and subthreshold strangeness production. These data were reproduced by various microscopic transport model calculations, providing, up to date, the best constraint for the EOS of symmetric matter with an incompressibility of about 200 MeV for densities up to twice the saturation density. This article reviews the experimental results on subthreshold kaon production together with the theoretical interpretation and gives a brief outlook towards future experiments at higher densities.

The Ξ-nuclear potential constrained by recent Ξ− hypernuclei experiments

The Ξ-nuclear potential is investigated in the quark mean-field (QMF) model based on recent results on the Ξ− + 14N () system. The experimental data on the binding energy of 1p-state Ξ− hyperon in hypernuclei in KISO, IBUKI, E07-T011, E176-14-03-35 events are merged as MeV. With this constraint, the coupling strengths between the ω vector meson and Ξ hyperon are fixed in three QMF parameter sets. At the same time, the Ξ− binding energy of 1s state in is predicted as MeV with the same interactions, completely consistent with the data from the KINKA and IRRAWADDY events. Finally, the Ξ-nuclear potential is calculated in the symmetric nuclear matter in the same framework. It is found to be U Ξ = −11.96 ± 0.85 MeV at nuclear saturation density, which is important for the discussions of the role of strangeness in a neutron star.

The Interplay of Conjugation and Metal Coordination in Tuning the Electron Transfer Abilities of NTA-Graphene Based Interfaces.

An artificial leaf is a concept that not only replicates the processes taking place during natural photosynthesis but also provides a source of clean, renewable energy. One important part of such a device are molecules that stabilize the connection between the bioactive side and the electrode, as well as tune the electron transfer between them. In particular, nitrilotriacetic acid (NTA) derivatives used to form a self-assembly monolayer chemisorbed on a graphene monolayer can be seen as a prototypical interface that can be tuned to optimize the electron transfer. In the following work, interfaces with modifications of the metal nature, backbone saturation, and surface coverage density are presented by means of theoretical calculations. Effects of the type of the metal and the surface coverage density on the electronic properties are found to be key to tuning the electron transfer, while only a minor influence of backbone saturation is present. For all of the studied interfaces, the charge transfer flow goes from graphene to the SAM. We suggest that, in light of the strength of electron transfer, Co2+ should be considered as the preferred metal center for efficient charge transfer.

Tumor cell and microvessel densities during the growth of a brain tumor: A theoretical study

Mathematical model for the tumor growth incorporating energy supply and requirement, angiogenesis efficiency and effect of elasticity of adjacent normal tissue to understand tumor biology and predict saturation status is rare to find. This study is conducted to address these issues. We propose mathematical expressions to explain alterations of tumor cell density (nT), microvessel density (MVD), and growth rate(r) during the development of brain tumors. We assume that nT increases during the growth of the tumor due to the increase of external pressure from the initial cell density (nT0); nT0 is same as the external normal tissue. The rate of increase in tumor cells (dNT/dt) depends on the rate of energy available for the creation of new cells and the energy required for a single cell division(γ). Due to the increase of tumor cell density, hypoxia is developed, which up-regulates the secretion of vascular endothelial growth factor (VEGF) and new capillaries are generated. Therefore, the surface area density of capillaries (Acs) in tumors increases. Hence, we consider that Acs(t) ∞ nT(t). A modified logistic equation is developed. Temporal variations of nT(t), Acs(t), r(t) and tumor cell population ‘NT(t)’ are examined. The expressions of saturated cell density(nTM), saturated microvessel surface area density (AcsM) and tumor saturation time(Ts) are formulated. An important feature, tumor saturation factor ‘fTS’ is determined. When fTS<1, a tumor will saturate at Ts, and nTM depends solely on fTS.

Special point "trains" in the M-R diagram of hybrid stars

We present a systematic investigation of the possible locations for the special point (SP), a unique feature of hybrid neutron stars in the massradius diagram. The study is performed within the two-phase approach where the high-density (quark matter) phase is described by the covariant nonlocal Nambu–Jona-Lasinio (nlNJL) model equation of state (EOS) which is shown to be equivalent to a constant-sound-speed (CSS) EOS. For the nuclear matter phase around saturation density different relativistic density functional EOSs are used: DD2p00, its excluded-volume modification DD2p40 and the hypernuclear EOS DD2Y-T. In the present contribution we apply the Maxwell construction scheme for the deconfinement transition and demonstrate that a simultaneous variation of the vector and diquark coupling constants results in the occurrence of SP "trains" which are invariant against changing the nuclear matter EOS. We propose that the SP train corresponding to a variation of the diquark coupling at constant vector coupling is special since it serves as a lower bound for the line of maximum masses and accessible radii of massive hybrid stars.

Constraints on the curvature of nuclear symmetry energy from recent astronomical data within the KIDS framework

In this paper, we investigate the density dependence of the nuclear symmetry energy [Formula: see text] in the KIDS (Korea-IBS-Daegu-SKKU) framework for the nuclear equation of state (EoS) and energy-density functional (EDF). The aim is to constrain the value of the curvature parameter ([Formula: see text]) based on recent astronomical data. First, assuming a standard saturation point, we calculate bulk nuclear properties within KIDS-EDF for different values of the compression modulus of symmetric nuclear matter ([Formula: see text]) and of the leading-order symmetry energy parameters, i.e., the symmetry energy ([Formula: see text]) and slope ([Formula: see text]) at saturation density, each within a broadly accepted range, as well as [Formula: see text]. All of the above EoS parameters are varied independently of each other. The skewness parameter ([Formula: see text]) is presently kept fixed at 650[Formula: see text]MeV. For all EoS parameter sets which describe the selected nuclear data within better than [Formula: see text], we calculate the neutron star EoS and mass–radius relation and analyze the results in terms of Pearson correlation coefficients [Formula: see text]. We find that the value of [Formula: see text] is strongly correlated with the radius of both a canonical and a massive star [Formula: see text]. If we impose that all known astronomical constraints on the neutron star radii must be satisfied, we deduce [Formula: see text]. As a result, the symmetry energy as a function of the density is consistently found to have an inflection point at [Formula: see text]. We take the opportunity to report that the neutron skin thickness of [Formula: see text]Pb shows no correlation at all with the neutron star radii [Formula: see text], in contrast with studies which focus on the role of [Formula: see text] only.

Groundwater Affects the Geomorphic and Hydrologic Properties of Coevolved Landscapes

AbstractThe hydrologic dynamics and geomorphic evolution of watersheds are intimately coupled—runoff generation and water storage are controlled by topography and properties of the surface and subsurface, while also affecting the evolution of those properties over geologic time. However, the large disparity between their timescales has made it difficult to examine interdependent controls on emergent hydrogeomorphic properties, such as hillslope length, drainage density, and extent of surface saturation. In this study, we develop a new model coupling hydrology and landscape evolution to explore how runoff generation affects long‐term catchment evolution, and analyze numerical results using a nondimensional scaling framework. We focus on hydrologic processes dominating in humid climates where storm runoff primarily arises from shallow subsurface flow and from precipitation on saturated areas. The model solves hydraulic groundwater equations to predict the water‐table elevation given prescribed, constant groundwater recharge. Water in excess of the subsurface capacity for transport becomes overland flow, which generates shear stress on the surface and may detach and transport sediment. This affects the landscape form that in turn affects runoff generation. We show that (a) four dimensionless parameters describe the possible steady state landscapes that coevolve under steady recharge; (b) hillslope length increases with increasing transmissivity relative to the recharge rate; (c) three topographic metrics—steepness index, Laplacian curvature, and topographic index—together provide a basis for interpreting landscapes that have coevolved with runoff generated via shallow subsurface flow. Finally we discuss the possibilities and limitations for quantitative comparisons between the model results and real landscapes.

Mechanism analysis of metalloid elements affecting amorphous forming ability and magnetic properties of Co-Y-B alloy

&lt;sec&gt;Co-based metallic glass (MG) is a new class of soft magnetic material and has promising applications in high-frequency fields due to its high magnetic permeability and low coercivity. However, this kind of MG has poor glass-formation ability (GFA) and relatively low saturated magnetic flux density, so its application scope is limited. The atomic size of metalloid element M (B, C, Si, and P) is small, which can easily enter into the gap between atoms, and there is a relatively large negative enthalpy of mixing between metalloid element and metal element. Therefore, alloying with metalloid element M is an effective method to improve the GFA while maintaining superior soft magnetic properties for Co-based MG. In this work, the formation process of Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;M&lt;sub&gt;10&lt;/sub&gt; MG is simulated by &lt;i&gt;ab initio&lt;/i&gt; molecular dynamics (AIMD) method, and the effects of the addition of metalloid elements C, Si, P on the GFA and magnetic properties of Co-Y-B MGs are investigated. It is devoted to analyzing the relationship between local atomic structure and property at an atomic level.&lt;/sec&gt;&lt;sec&gt;According to the results of the characterization parameters of local atomic structure (pair distribution function, coordination numbers, chemical short-range order, Voronoi polyhedron index, local five-fold symmetry, and mean square displacement), it is found that the GFA of the four alloys is different due to their different local atomic structures. Both Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;C&lt;sub&gt;10&lt;/sub&gt; alloy and Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;P&lt;sub&gt;10&lt;/sub&gt; alloy possess a higher fraction of prism structure, weaker solute segregation between B/C-C and B/P-P atoms, higher atomic diffusivity in the supercooled state (1100 K), and hence weakening the GFA of the alloys. The Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;Si&lt;sub&gt;10&lt;/sub&gt; alloy has a higher fraction of icosahedral-like structure, stronger attraction between Co-Si atoms and the solute segregation between B/Si-Si atoms, lower atomic diffusivity in the supercooled state, thereby increasing the GFA. Therefore, the addition of Si is beneficial for enhancing the GFA, while the addition of C or P will reduce the GFA, that is, the GFA of the four alloys decreases in the order of Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;Si&lt;sub&gt;10&lt;/sub&gt; &gt; Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;25&lt;/sub&gt; &gt; Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;P&lt;sub&gt;10&lt;/sub&gt; &gt; Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;C&lt;sub&gt;10&lt;/sub&gt;. In terms of magnetic properties, with the addition of C, Si, P elements, the total magnetic moment of Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;M&lt;sub&gt;10&lt;/sub&gt; (M = B, C, Si, P) alloy decreases in the following order: Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;25&lt;/sub&gt; &gt; Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;Si&lt;sub&gt;10&lt;/sub&gt; &gt; Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;C&lt;sub&gt;10&lt;/sub&gt; &gt; Co&lt;sub&gt;72&lt;/sub&gt;Y&lt;sub&gt;3&lt;/sub&gt;B&lt;sub&gt;15&lt;/sub&gt;P&lt;sub&gt;10&lt;/sub&gt;. The stronger p-d orbital hybridization between Co-Si atoms enhances the ferromagnetic exchange interaction, leading the total magnetic moment to be less affected by Si addition.&lt;/sec&gt;

Complete stress release in monolayer ALD-Al2O3 films based on mechanical equilibrium homeostasis to realize a bending radius of 1 mm.

Low-temperature-deposited, transparent, high-barrier-performance atomic layer deposition (ALD) Al2O3 films are widely utilized to protect organic optoelectronic devices. However, because the internal compression residual stresses result in poor mechanical properties, these films are unable to realize independent encapsulation. In this work, we propose a pre-bending and substrate thermal expansion process to fabricate low-residual-stress ALD-Al2O3 films by multistep adjustment of mechanical equilibrium homeostasis, compare and analyze the key properties of the films to determine the optimal processing conditions, and adjust the surface area differences between the film and the substrate to acquire a flat-bottom encapsulation substrate. Therefore, fewer cracks form in ALD-Al2O3 deposited at 40 °C, and no significant increase in the water-vapor-transmission rate (WVTR) occurred after multiple bending processes at a 3 mm radius. Furthermore, both the bending radius for the first crack generation and crack saturation density were optimal, resulting in excellent mechanical stability, and a bending radius of 1 mm was achieved. Finally, we confirm the feasibility of the monolayer ALD-Al2O3 prepared by our process for applications in OLEDs. The encapsulated OLED maintained 94% of its initial efficiency after 10 days of bending in a harsh environment at 30 °C and 90% relative humidity.

Structure of two-and three-alpha systems in cold neutron matter

We present stability and structure of two-and three-alpha systems embedded in dilute cold neutron matter. By solving a few-alpha Schrödinger equation with quasiparticle properties, i.e.,effective mass and induced two-and three-alpha interactions, which are evaluated in terms of Fermi polarons,itis shown that 8Be and the Hoyle state become bound at densities of about10−4 and 10−3 of the saturation density, respectively. It is also seen that, under cold neutron matter environment, both systems become smaller than the corresponding systems in vacuum. Our results would affect astrophysical models for stellar collapse and neutron star mergers, as well as relevant reaction rates for nucleosynthesis.

Физико-математическая модель переноса газообразного кремния в ходе высокотемпературного силицирования углеродных композитных материалов

We propose a new physical and mathematical model for description of silicon vapor high-temperature transfer under medium vacuum conditions from the melt mirror to the surface of an absorbing porous medium in an atmosphere of residual gas. The developed model is simplified to the greatest extent possible and is intended for further numerical implementation in the course of modeling a non-stationary three-dimensional process of high-temperature siliconization of arbitrary-shaped porous carbon products under the condition of a complex distribution of silicon sources. The physical and mathematical model of transport consists of only one non-linear partial differential equation for the silicon vapor concentration in an atmosphere of argon or any other residual gas. In the limiting case of the simplest geometry and one-dimensional formulation of the problem, we obtained a stationary analytical solution that explains the anomalously large silicon vapor flux into the porous material in full-scale experiments. The obtained analytical solution for the studied gas mixtures is expressed in terms of the known verified values of the material parameters. It shows that despite the low saturation density of silicon vapor, the vapor-liquid-phase process of high-temperature siliconization of carbon materials is physically possible in a reasonable time.