物理最新文献

Doped ceria electrolytes are extensively studied and applied in intermediate-low temperature solid oxide fuel cell (IT-SOFC). Ce_0.79Gd_0.2-xCa_xCu_0.01O_2-δ electrolytes were synthesized by the ultrasonic-assisted sol-gel self combustion sintering method. The experimental results demonstrate that incorporating 1.0 mol% Cu into gadolinium-doped ceria (GDC) enables a reduction in sintering temperature by 500 °C, while Ca co-doping effectively increases oxygen vacancy formation, achieving a dense electrolyte with comparable ionic conductivity. Among these, the Ce₀.₇₉Gd₀.₁₅Ca₀.₀₅Cu₀.₀₁O_2-δ electrolyte demonstrated the highest conductivity, showing a tenfold increase compared to conventional Ce_0.79Gd_0.2-xCa_xCu_0.01O_2-δ electrolytes, with a conductivity of 0.054 S·cm⁻¹ at 800 °C and an activation energy of 0.88 eV.

Starting from a generic Lagrangian, we discuss the number of propagating degrees of freedom in the framework of generalised non-linear electrodynamics when a photon-background split is applied. We start by stating results obtained in a previous paper, before modifying the action to an equivalent form. Within this new formulation, we highlight the presence of an effective mass and consider the mechanical reduction of the model to ensure the positivity of said mass. We then study the constraint algebra of the model and show that we shift from a model with two first-class to two second-class constraints, which implies the propagation of an additional degree of freedom. We also show that the Hamiltonian is bound from below and thus does not suffer from Ostrogradski-type instabilities. We conclude by deriving the propagator for the model, and discussing the potential link between the nature of this additional polarisation and the mechanism behind the effective mass generation in this class of models.

Long-term, high-performance nanocatalyst development requires environmentally friendly synthesis, defect engineering, and multifunctionality. CuFe₂O₄ nanospinels were ecologically produced using phytogenic combustion and bioactive fuels derived from Plumeria rubra and Caesalpinia pulcherrima. The lattice constants were 4.46 and 4.88 Å, while the Plumeria and Caesalpinia crystallites had sizes of 11.56 and 10.82 nm, respectively. FESEM analysis revealed semi-spherical nanoparticles with diameters of 35.0 and 36.7 nm. UV–Vis spectroscopy revealed that Plumeria and Caesalpinia defects serve as mediators of strong electronic transitions. The indirect bandgap is 2.22 eV, while the direct bandgap is adjustable up to 2.60 eV. Photoluminescence emission at 486–624 nm revealed oxygen vacancies, antisite disorder, mixed-valence Cu⁺/Cu³⁺ and Fe³⁺ centres, and Jahn–Teller distortions. Electrochemical profiling revealed reversible redox processes with peak currents of 1.95 mA and −1.83 mA, providing sensitive biosensing capabilities. The CuFe₂O₄ electrode's rapid electron-transfer kinetics and numerous electroactive sites resulted in low detection limits of 0.172 μM for L-histidine and 0.329 μM for D-fructose. Plumeria nanoparticles had a higher radical-quenching efficiency (IC₅₀) of 107.42 mg mL⁻¹ in DPPH-based antioxidant tests than Caesalpinia nanoparticles (IC₅₀) of 978.16 mg mL⁻¹. After 120 min of sunlight exposure, the Plumeria catalyst reduced anthocyanin dyes by 71.84%, while the Caesalpinia catalyst reduced them by 75.86%. Kinetic analysis confirmed the pseudo-first-order behaviour at rate constants of 0.0106 and 0.0114 per minute. The two catalysts' efficiency remained between 65 and 69% after four degradation cycles. This study uses phytogenic combustion to create CuFe₂O₄ nanospinels that are defect-free, optoelectronically flexible, and catalytically stable. They are scalable nanomaterials with a wide range of beneficial properties, including antioxidant, photocatalytic, structural, optical, electrochemical, and advanced biosensing capabilities, as well as pollution degradation and multifunctional catalysis.

This study investigated the electrochemical characteristics of NdFeO₃ nanocomposite improved with added small quantity of MXene. The NdFeO₃/MXene was synthesized using a standard solve-thermal technique and analyzed using X-ray diffraction, Fourier Transform Infrared Spectroscopy, etc . The electrochemical efficiency of the composite was tested for supercapacitors (SCs). The compositive was investigated in 3 M KOH electrolytic solution where NdFeO₃/MXene was pasted on nickel foam and served as working electrode. CV revealed that NdFeO₃/MXene has reached the capacitance of 1148.12 F g⁻¹ (5 mV s⁻¹). GCD research revealed that NdFeO₃ nanoparticles along with NdFeO₃/MXene nanocomposite had capacitance values of 703.17 F g⁻¹ as well as 1315.06 F g⁻¹ at 1 A g⁻¹. The NdFeO₃/MXene indicated that greater E_d along with P_d is 17.99 Wh kg⁻¹, 510 W kg⁻¹. After 4700 cycles, the material containing NdFeO₃/MXene nanocomposite remained stable. Chrono test confirmed high stability of composite material. The electrochemical investigation of generated NdFeO₃ nanocomposite shown that addition of MXene caused in a hybrid capacitive nature, as the suggested NdFeO₃/MXene can be used as SCs electrodes in energy storage. The NdFeO₃/MXene nanocomposite exhibits excellent electrochemical performance as compared to previously reported perovskite–MXene, due to its optimized hetero-interface, greater electrical conductivity, as well as abundant redox active site. The incorporation of NdFeO₃ enhanced pseudo-capacitive behavior, while MXene provides quick electron transport pathway, resulting in higher specific capacitance, outstanding rate capability, and cyclic stability to earlier perovskite–MXene.

Graphical abstract

This study presents the first systematic molecular dynamics investigation of polyethylene (PE) and polypropylene (PP) nanocomposites reinforced with randomly functionalized single-walled carbon nanotubes (SWCNTs). Armchair (8,8) and zigzag (14,0) SWCNTs with nearly identical diameters (10 Å) were functionalized with hydrogen and fluorine atoms at 5–25% functionalization levels and incorporated into polymer matrices at 10% volume fraction. Representative volume elements (RVEs) were subjected to tensile loading simulations up to failure using Tersoff and Dreiding potentials to quantify Young’s modulus, maximum stress, failure strain, strain energy, and toughness. Results demonstrate that increasing functionalization consistently reduces mechanical properties across all systems, with Young’s modulus decreasing from range of 60–70 GPa to the range of 40–50 GPa and maximum stress declining from around 11 GPa. Zigzag SWCNTs generally outperformed armchair configurations in stiffness and strength, while armchair SWCNTs exhibited superior strain capacity. PE-based nanocomposites showed slightly better performance than PP-based systems for certain properties. Although CNT–polymer nanocomposites have been widely studied, a systematic comparison of randomly applied hydrogen and fluorine functionalization in both PE and PP matrices has not been conducted before. Comprehensive comparative analysis between functionalization types, polymer matrices, and nanotube chiralities provides essential design guidelines for optimizing nanocomposite performance in various applications.

The Lee–Wick pseudo-quantum electrodynamics in the presence of a Chern–Simons term is studied in this paper. The paper starts with a non-local lagrangian density that sets the pseudo-Lee–Wick electrodynamics defined on a (1+2) space-time added to a non-local Chern–Simons topological term. Thus, we obtain the Lee–Wick–Chern–Simons pseudo-electrodynamics as a most complete gauge invariant model that provides a light mass associated with the Chern–Simons parameter, and also includes a Lee–Wick heavy mass. We investigate classical aspects as the potential energy for the interaction of static charges through the gauge propagator. The causality of theory is discussed through the retarded Green function in the coordinate space. The gauge field of the Lee–Wick–Chern–Simons pseudo-electrodynamics is minimally coupled to the fermions sector that includes new degree of freedoms, as a Lee–Wick heavy fermion partner of the electron. The perturbative approach for the theory is presented via effective action in which we obtain the Ward identities. We study the quantum corrections at one loop, as the electron self-energy, the vacuum polarization, and the 3-vertex. We show that the Lee–Wick mass has a fundamental role in these results, where it works like a natural regulator of the ultraviolet divergences. The (g-2) factor for the electron is obtained as function of the LW mass, and of the CS parameter. Through the optical theorem, the Lee–Wick–Chern–Simons pseudo-electrodynamics is unitary at the tree level.

We present a comprehensive spectral study of the supersoft X-ray source RX J0925.7-4758 using six observations from ASCA, Chandra, XMM-Newton and NICER, spanning 25 years. Our primary objective is to identify a robust non-local thermodynamic equilibrium (NLTE) spectral model that consistently fits the continuum emission across all data sets. A systematic fitting procedure revealed that only a pure-hydrogen NLTE model with effective gravity (log g = 7) could achieve acceptable fits for all observations. The composite model incorporates photoelectric absorption, interstellar medium (ISM) absorption with non-solar abundances and discrete absorption edges at known threshold energies. The effective temperatures are found to be of the order of (sim !!! 10^{5}) K and the luminosities are estimated to be (sim !! 10^{41} mathrm {erg, s}^{-1}), suggesting that the emission arises from a hot accretion disk around a white dwarf undergoing steady hydrogen burning. Additionally, we examine the relative strengths of the bound-free absorption edges in all six observations. While consistent trends are seen in earlier missions, the NICER data show variability in edge dominance, likely due to the instrumental or calibration differences. Although the continuum spectra can be modelled satisfactorily, high-resolution grating spectra from XMM-Newton reveal complex line features, including P Cygni profiles, which are not reproduced by static atmosphere models. This highlights the need for future NLTE+wind models to interpret these data more completely. Our study lays a foundation for such future analyses of high-resolution grating spectra of supersoft X-ray sources.

A novel functionalized quinoline derivative, (E)-N’-(7,7-dimethyl-2-oxo-4-phenyl-2,3,4,6,7,8-hexahydroquinazole-5(1 H)-ylidene) isonicotinohydrazide, is developed and produced for potential therapeutic and nonlinear optical (NLO) uses. The structural elucidation is supported by FT-IR, UV-vis, NMR, and mass spectrometry, and the results are supported by DFT calculations at the B3LYP/6-31G(d, p) level. AIM analysis is used to analyze intramolecular interactions. NLO investigations indicate significant hyperpolarizability (β = 5.498 × 10⁻³⁰ esu), with values higher than those of urea. Frontier Molecular Orbital, MEP, and TD-DFT simulations in solvents yield a band gap of 3.80 eV, which has excellent electrical and optical properties. The NBO and Fukui analyses reveal stable donor-acceptor interactions and reactive regions. The SwissADME examination validated drug-likeness, and molecular docking revealed efficient interaction with tuberculosis target proteins, indicating anti-TB activity. These findings suggest that the compound not only possesses promising electronic characteristics but also demonstrates potential therapeutic applications. Overall, the molecule combines high biological activity with improved NLO responsiveness, making it a viable option for both therapeutic and photonic applications.

This work presents a theoretical and numerical investigation of the optical properties and slow-light behavior of CdS@ITO core–shell quantum dots (CSQDs) designed for operation in the 1310 nm and 1550 nm telecom bands. Using quasi-static electrodynamics, Maxwell–Garnett effective medium theory, and the Drude–Sommerfeld model, we demonstrate that the ITO shell supports low-loss infrared plasmonic resonances with extinction coefficients below (kappa < 0.06). Hybrid exciton–plasmon coupling between the CdS core and ITO shell produces strong local field enhancement ((|F|^{2}> 1000)) and pronounced normal dispersion, enabling slow-light behavior with group velocities as low as (v_{g} approx 0.05c). Geometric tuning of the core radius (3–5 nm) and shell thickness (6–8 nm) enables precise alignment of the plasmonic resonance with standard telecom wavelengths. Finite element simulations confirm intense field localization at the CdS/ITO interface and enhanced internal fields within the CdS core, supporting Kerr-type nonlinear effects relevant for optical modulation. Parametric mapping of extinction, refractive index, and group index further demonstrates robust spectral tunability and low-loss performance across the near-infrared region. These findings identify CdS@ITO CSQDs as promising, CMOS-compatible nanostructures for compact optical delay lines, all-optical modulators, and other integrated photonic components operating within the telecom band.