物理最新文献

Injection-Dependent Lifetime Spectroscopy (IDLS) is used within this study for a parameterisation of interstitial iron Fe_i in p type Czochralski <100> silicon wafers. The first step is dedicated to study the presence of iron contamination using the crossover method for Fe_i and Iron-Bore pairs (Fe-B) dissociation, then the IDLS supported by the Defect Parameter Solution Surface (DPSS) are performed for the determination of capture coefficient σ_n/σ_p (σ_n, σ_p are the capture cross section for electrons and holes respectively) and the energy level in the band gap of Fe_i related defect (E_t). The obtained parameters, σ_n/σ_p= 21 and E_t= E_V+0.38 eV, where E_v is the valence band energy, were used to fit the experimental Shockley–Read–Hall (SRH) lifetime provided by Quasi-Steady-State PhotoConductance measurement (QSSPC) to assess σ_n and σ_p. The objective of the second part of this work was to demonstrate the relationship between σ_n and the concentration of [Fe_i]. It is important to note that the electron-capture cross-section of Fe_i has been determined less accurately in the literature compared to the hole-capture cross-section and the energy level within the band gap E_t. To validate the relationship between σ_n and the concentration of Fe_i, we assumed a value of 7×10^-17 cm² for σ_p and a value of E_V+0.38 eV for energy level of trap E_t, as reported in the literature. Subsequently, the value of σ_n was determined through the application of the equation K = σ_n/σ_p, which yielded a result of 21. The resulting parameters were then employed in the fitting of experimental data of the Shockley–Read–Hall lifetime (τ_srh) versus injection level (∆n) [cm^-3].

In this work, a charged fluid system is studied by employing the complexity factor formalism for a static spherical spacetime. We proceed by calculating two distinct mass functions and obtaining the Einstein field equations for the anisotropic fluid. Following Herrera’s methodology, we designate ({Y}_{TF}) as the complexity factor as it integrates the two fundamental dynamic components like the density inhomogeneity and pressure anisotropy. Additionally, the field equations are addressed by applying a few constraints, with the first being the condition of zero complexity. By implementing two distinct forms for the radial metric potential, we derive two independent solutions. The unknowns involved in these models are then found using the junction conditions by taking into account the Reissner–Nordström exterior metric. Subsequently, observed data from multiple stars is used to generate a visual depiction of the obtained solutions. Our analysis demonstrates that both proposed models maintain physically stable and viable profiles, highlighting the critical role of the vanishing complexity condition in constructing anisotropic fluid solutions under the presence of an electric charge.

This work pioneers a universal framework for quantifying quantum entanglement in nuclear systems by innovatively integrating quantum distance metrics and machine learning. We introduce a framework for quantifying entanglement in nuclear spin systems using quantum distance measures (fidelity, trace distance and Bures distance ((D_textrm{B})) ). A universal scaling law (D_textrm{B} propto Gamma ^{-0.85}) links Bures distance to nuclear decay width, experimentally validated in (^{56}text {Fe}(n,gamma )) reactions ((D_textrm{B} = 0.62 pm 0.04)). Machine learning achieves 94% prediction accuracy, revealing 18% entanglement enhancement near shell closures. Three entanglement phases guide quantum technology applications: (^{56}text {Fe}) for memory ((D_textrm{B}>0.6), (tau _Dsim 10^{-25}) s) and (^{6}text {Li}) for sensing. The study bridges quantum information theory and nuclear physics, offering transformative tools for both fields.

Drug resistance in microorganisms is a growing global threat, highlighting the urgent need for novel therapeutic agents. This study evaluates the antibacterial and anti-SARS-CoV potential of fungal endophytes isolated from A. marmelos. Among 16 endophytes screened, the ethyl acetate extract of the #3 AMLBF strain (Fusarium vanettenii) exhibited the strongest antibacterial activity against several pathogens. This extract showed minimum inhibitory concentrations (MICs) ranging from 0.49 to 0.8 µg/ml. GC/MS analysis of the active extract identified 45 compounds. Furthermore, molecular docking against the SARS-CoV-2 spike glycoprotein revealed nine potential ligands, with Anthraergosta-5,7,9,22-tetren-3-ol p-chlorobenzoate showing the most potent binding affinity (− 10.2 kcal/mol), a value exceeding that of the standard chloroquine (− 6.5 kcal/mol). These results indicate that the organic extract from this fungal strain is a promising candidate for the discovery of new antimicrobial agents.

Graphical abstract

Potential of endophytic fungi

Accurate neutron capture cross sections are essential for constraining nuclear reaction models and for applications in reactor technology and astrophysical nucleosynthesis. Among potential reference isotopes, holmium-165 exhibits favorable nuclear characteristics but lacks high-precision experimental data in the resolved resonance region. In this work, the neutron capture yield of ¹⁶⁵Ho was measured using the 4(pi ) (hbox {BaF}_2) Gamma Total Absorption Facility (GTAF) at the Back-streaming White Neutron Beamline (Back-n) of the China Spallation Neutron Source (CSNS). Resonance parameters in the energy range from 1 to 1.0 keV were extracted through Bayesian R-matrix analyses performed with the code SAMMY. For 18 s-wave resonances below 100 eV, the resonance energy (E_R), neutron width (varGamma _n), and radiative width (varGamma _gamma ) were determined. The distribution of mean level spacings follows the Wigner–Dyson form with (langle D_0rangle ) = 4.53(3) eV, indicating chaotic compound-nucleus behavior, while the reduced neutron widths obey the Porter–Thomas (chi ^2) distribution with one degree of freedom, consistent with a single entrance channel. The mean radiative width for s-wave resonances was (langle varGamma _gamma rangle ) = 88.10(89) meV, and the s-wave neutron strength function was determined to be (10^{4}S_0) = 2.01(1), in excellent agreement with evaluated values in the Atlas of Neutron Resonances and the ENDF/B-VIII.0 library. These results provide an improved experimental foundation for neutron-capture modeling and for refining nuclear data evaluations involving odd-odd systems.

Photosynthesis is a simple reaction for any plant, but it has not been achieved artificially due to the difficulty in radiation entropy production by processing PAR (photosynthetically active radiation). In this study, a plant is shown to be a self-organising dissipative structure; since, it’s leaf generates radiation entropy for the existence of plant with possible growth. Entropy-energy ratio (s_E) of PAR released after processing (s_E,rel) much exceeds s_E of light absorbed, s_E,in (< < s_E,rel). Plant builds its negentropy (left| {s_{{{text{neg}},{text{rad}}}} } right|) by the difference, (s_{{text{E,rel}}} - s_{{text{E,in}}}) , but only a part of this difference can be the source of free energy as plant-growth. The remaining part of (left| {s_{{{text{neg}},{text{rad}}}} } right|) is dissipated as the excess payment of negentropy debt, towards mandatory 2nd Law compliance. Change from low s_E,in to high s_E,rel by the plant-leaf is amplified by a huge factor, c², while determining (left| {s_{{{text{neg}},{text{rad}}}} } right|); where, c is the speed of light. Therefore, even a small increase in s_E,rel and small reduction in s_E,in can significantly increase (left| {s_{{{text{neg}},{text{rad}}}} } right|). Thermodynamic performance of photosynthesis depends on the processing level of PAR, (Pi_{{{text{E}},{text{leaf}}}} = left( {{{s_{{{text{E}},{text{rel}}}} } mathord{left/ {vphantom {{s_{{{text{E}},{text{rel}}}} } {s_{{{text{E}},{text{in}}}} }}} right. kern-0pt} {s_{{{text{E}},{text{in}}}} }}} right)), (left| {s_{{{text{neg}},{text{rad}}}} } right|), and is limited by the maximum photosynthetic efficiency in PAR, ({upeta }_{{{text{ph}},{text{PAR}}_{text{max}}}}) (it increases with (Pi_{{{text{E}},{text{leaf}}}})).

Graphical Abstract

In this work, we explore the effect at the cosmological level of the extra contribution arising from the Geodetic Brane Gravity model within a thermodynamical perspective. As already known, the universe seen as an extended object embedded within a higher-dimensional spacetime modifies the dynamical background equations, which in turn results in correction contributions to the entropy and temperature of the apparent horizon. Additionally, we investigate the possibility that the apparent horizon and the bulk remain in thermal equilibrium across various matter contents, demonstrating that such properties are highly sensitive to the equation-of-state parameter.

This study examines the linear instability of double-diffusive rotational convection in a horizontal layer of Navier–Stokes–Voigt fluid with stress-free boundary conditions. The onset condition for convection is derived in closed form using normal mode analysis. Double-diffusive convection in the presence of rotation serves as an example of a triple-diffusive fluid system, exhibiting convective behaviours not observed in double-diffusive Kelvin–Voigt fluid models. Numerical calculations reveal several novel and significant phenomena under specific parametric conditions: (i) the emergence of a closed and disconnected oscillatory neutral stability curve from its stationary counterpart, necessitating three Rayleigh numbers to characterise the onset of instability, unlike the classical single-parameter framework; (ii) the destabilisation of a double-diffusive Navier–Stokes–Voigt fluid layer under the influence of rotation and (iii) the destabilisation of rotating convection in a Navier–Stokes–Voigt fluid layer due to the addition of a stable solute concentration gradient. These findings highlight the complex interplay between rotation, solutal stratification and viscoelasticity, offering fresh insights with implications for industrial processes, geophysical flows and astrophysical environments. Validation against established benchmarks affirms the accuracy of the analysis and demonstrates how, even within the Navier–Stokes–Voigt framework, traditionally stabilising factors can collectively act as catalysts for convective instabilities under specific conditions.

In the present report structure and morphology dependent optical characteristics of the pure and zinc oxide doped tungsten oxide films are presented. Thin films having crystallites in the nanometer regime are deposited using RF-Magnetron sputtering. Morphology of the films are analysed using Atomic Force Microscopy images. Root Mean Square surface roughness values of the heavily ZnO doped films exhibits higher values relative to other films. The optical band gap and the transmittance of the samples are studied using UV-Visible spectroscopic measurement. Compared to undoped film the optical band gap energy presents a red shift as a result of oxygen deficiency due to ZnO doping. Photoluminescence measurements reveals that the doping induced oxygen deficiency related emission peaks are present in the doped films other than the band edge emission which is the only emission in the undoped one. Using spectroscopic ellipsometric analysis the optical constants of the films are analysed in detail in view of practical application.