物理最新文献

One of the additives that positively influence the parameters of the electrolyte for lithium-ion cells are ceramic nanoparticles, such as SiO₂ and α-Al₂O₃. However, they tend to agglomerate and sediment, which is an unfavorable phenomenon. An effective strategy to prevent this is to modify the surface of the particles with polymeric compounds, which can increase compatibility and stability in the electrolyte system. To reduce agglomeration and sedimentation, a method was developed to modify aluminum oxide and silica particles using aluminum carboxylate, which chemically combines with inorganic particles that have hydroxyl groups on their surface through an alkoxide bond. This method allows the introduction of oligooxyethylene groups to the ceramic surface, thus obtaining more stable systems. The effectiveness of this modification was confirmed through dynamic light scattering (DLS) measurements of particle size in liquid organic solvents, which are potential solvents for liquid electrolytes in lithium-ion cells. The modified nanosilica and aluminum oxide particles were then used as additives to solid polymer electrolytes made of poly(ethylene oxide) (PEO). This led to higher conductivity values compared to the use of unmodified fillers. The obtained values of lithium transference number for solid polymer electrolyte with PEO/CF₃SO₃Li and nanosilica or aluminum oxide modified with aluminum carboxylate are equal to 0.32–0.40.

The study of fission yields has a major impact on the characterization and understanding of the fission process and its applications. Mass yield evaluation represents a key element in order to perform the best estimation of independent and cumulative fission product yields. Today, the lack of analysis-based correlation matrix between the different fission observables induces many inconsistencies in the evaluations. In particular, the mass yield uncertainties are drastically overestimated in comparison to chain yields while these two quantities only differ from the emission of delayed neutrons. In this work, a new consistent process of mass yield evaluation is proposed taking into account the description of the covariance matrix. For (^{235}text {U(n}_{text {th}}text {,f)}) mass yields, existing data cover a large range of produced masses which makes it possible to propose an evaluation of mass yields independently of any model with a precision closed to (1.5%) for the high yields. This new precision brings the possibility to discuss the origin of the structures in the post-neutron mass yields, in particular the consistency with the pre-neutron mass yields and the prompt neutron multiplicity per mass. The work is the first part of the (^{235}text {U(n}_{text {th}}text {,f)}) thermal neutron induced fission yield evaluation which will be included in the new JEFF-4 library.

The conservation of the number of nodes in the wavefunctions of one-electron diatomic quasimolecules is treated. The elaborated approach is focused on the behavior of separation constants and their relationship to the number of nodes as the distance between nuclei varies. By examining the separation constants for quasimolecules with different nuclear charges, we demonstrate the robustness of the number of nodes across different states and separations without explicitly defining the wavefunctions themselves.

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Transition-metal-oxide based perovskites belong to the strongly correlated electron system exhibiting composition dependent metal-insulator transition. Their electronic properties can be tuned by doping them with right material by right amount for application in the diverse areas of material science. This article presents the preparation of crystalline thin films of Fe-doped LaNi_1-xFe_xO₃ (x = 0, 0.1, 0.2, 0.4) on glass substrate by spin-coating of chemical solutions. Annealing the films at a suitable temperature for optimum time plays a crucial role in obtaining good crystalline samples. We performed structural characterizations of the films using X-ray diffraction spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Electrical conductivity of the films was measured by four-probe technique at 30˚ C, 50˚ C, 80˚ C, and 100˚ C. We observed a non-ohmic insulating behaviour for the sample with x = 0.4 while all the other films with lower doping level showcased linear voltage-current relationship with metallic temperature dependence.

Graphical Abstract

The electron impact excitation rate coefficients or effective collision strengths are one of the ingredients for plasma modeling or plasma diagnosis. The present work provides a computational implementation for calculating excitation rate coefficients using the Jena Atomic Calculator toolbox within the framework of the relativistic distorted wave approximation. To address the need for large-scale calculations involving complex shells and heavy atoms and ions, parallel programming is implemented to expedite the computation of cross sections, collision strengths, effective collision strengths and rate coefficients. As a case study, we have calculated collision strengths, effective collision strengths and rate coefficients for Fe XXII.

In this study, we explore the emergence of spatial patterns in a predator–prey model influenced by habitat loss, incorporating the effects of linear diffusion. By examining the stability of the system through the Jacobian matrix, we derive conditions for the occurrence of both Hopf and Turing bifurcations using analytical and numerical approaches. Numerical simulations yield Hopf bifurcation diagrams, revealing the system’s dynamic responses to varying conditions. Our findings contribute to the understanding of how habitat loss and harvesting affect the spatial dynamics in predator–prey systems, which are described by partial differential equations (PDEs) under flux boundary conditions. We also investigate the impact of habitat loss due to harvesting on spatial patterns, identifying formations such as spots and stripes as a result of changes in harvesting efforts. We analytically derive the conditions for Turing instability, which are confirmed through numerical validation.

Understanding the mechanisms governing stress localization in polycrystalline materials is paramount for optimizing their mechanical properties and performance. Here, we investigate the grain boundary-induced stress localization phenomenon during compression deformation of polycrystalline 316L stainless steel through a combination of experimental and computational approaches. Utilizing a custom-built indentation setup and crystal plasticity finite element (CPFE) simulations, we elucidate the intricate interplay between microstructural features, dislocation mechanisms, and stress distribution. Experimental results reveal significant stress concentrations at grain boundaries, while CPFE simulations demonstrate the influence of grain size on stress response, with finer grains exhibiting higher stresses due to increased accumulation of geometrically necessary dislocations (GNDs). Our findings underscore the critical role of microstructural features, particularly grain boundaries and grain size, in governing the mechanical behavior of polycrystalline materials under compression loading conditions. This study provides valuable insights for designing and optimizing materials for various engineering applications.

Through the application of mathematical epidemiology principles, the formulation of the soft drugs model is established, and the complete dynamics of this deterministic model are contingent upon the crucial parameter called the basic reproduction number, denoted as (R_{0}^{d}). The stochastic soft drug epidemic models are developed by considering the parametric and non-parametric stochastic perturbation techniques. Dynamics of the two different stochastic models are determined using the analog stochastic thresholds (R_0^{s_{1}}), (R_0^{s_{2}}), respectively. Introducing suitable Lyapunov functionals enables us to establish sufficient axioms for the extinction and permanence of soft drug users in both deterministic and stochastic models. Moreover, the sensitivity of the deterministic and stochastic thresholds to some important parameters involved in the models is illustrated. For the verification of our theoretical results, we develop some numerical simulations using the Euler–Maruyama scheme.

The present investigation examines the behaviour of compact relativistic objects characterised by static and spherically symmetric space–time for neutral anisotropic matter distribution. More specifically, we consider an equation of state (EoS), in which density and radial pressure are connected with each other quadratically. By smoothly matching the interior space–time with the exterior at the stellar surface, the appropriate values of the constant parameters for physically realistic solutions are obtained to model various compact stars. We explore the physical behaviour of compact stellar models SMC X-4, Vela X-1, CEN X-3, PSR J1614-2230, LMC X-4 and EXO 1785-248. Further, we describe several features of the compact stellar systems that exhibit physically acceptable attributes with no singularity. All important stability criteria, such as the energy conditions, causality conditions, Buchdhal condition and the adiabatic index are fulfilled by our neutral anisotropic compact star models. An in-depth comprehension of the physical characteristics of the proposed solution has been achieved through meticulous analytical and graphical examinations. By utilising this solution, the masses and radii of six compact stellar candidates mentioned above are optimised with the observed values obtained experimentally. The derived solution might be useful to enhance the understanding of the strong-field regimes and self-gravitating entities.

The main aim of this investigation is to study the heat transport and entropy generation of human blood as a hybrid nanofluid (HNF) containing gold (Au) and silver (Ag) nanoparticles inside a Darcy–Fochheimer porous stenotic artery in the presence of thermal radiation and magnetic field. The primary reason for adopting Au and Ag nanoparticles as nanomaterials for drug delivery is because they exhibit potential drug transport and imaging properties for treating stenosed artery. Furthermore, velocity slip and convective boundary conditions at the surface of the artery are considered in this study. A method of suitable similarity transformations has been utilised to convert the partial differential equations (PDEs) into dimensionless ordinary differential equations (ODEs) and using the bvp4c built-in solver in MATLAB mathematical software, numerical solutions have been obtained. The plots of the results show that the hybrid nanofluid (Au–Ag/blood) has greater thermal conductance than the normal nanofluid (Au/blood). The temperature and velocity of the blood gradually increase as the percentage of nanoparticles in the blood flow grows. The heat transference rate increases with increase in Biot number (Bi) and radiation (Nr) effect, which helps in removing the toxic plaque from the artery. Due to the contraction of the artery, dual solutions are found, but dual solutions cannot be found beyond the critical values of suction (S) and shrinking ((lambda )) parameters. The critical values (S_C) from computation are 1.5851, 1.5949 and critical values (lambda _C) are 0.652, 0.781 for Au/blood nanofluid (NF) and Au–Ag/blood hybrid nanofluid (HNF), respectively. Also, the stability of blood flow is achieved by finding the lowest eigenvalue. A positive minimum eigenvalue ((beta _1)) denotes the upper stable solution branch, whereas a negative minimal eigenvalue indicates the bottom unstable solution branch. The entropy of the blood as the HNF flow was found to increase with nanoparticle volume fraction ((phi _1, phi _2)), porous parameter (P) and magnetic parameter (M). These results will help greatly to avoid brain stroke or heart attack caused by the burst of an artery.