The European Physical Journal Plus最新文献

Normal and anomalous rotary photon drag is investigated in a spinning atomic medium via heat loss and gain. Significant modifications and controls are studied with varying heat loss and heat gain. The anomalous rotary photon is a function of heat loss and heat gain, as well as control field Rabi frequencies and detunings. The maximum rotary photon drag calculated is (pm 399) microradian at a heat loss of (0.8J) and is enhanced with the Rabi frequency of the control field. The relative phase of the control fields tunes anomalous drag to normal drag with heat loss and gain. The maxima of photon drag are shifted with the relative phase of the control fields toward heat loss and heat gain in the medium. The modified results of this manuscript are useful for optical switching and sensing as well as quantum-based Internet of Things (IoT) applications.

This report presents the comprehensive investigation of the effect of CuO concentration and thermal treatment on the properties of 60B₂O₃ + 10Bi₂O₃ + 10Na₂O + 5WO₃ + (15 − x)SrO + xCuO, where x = 0, 0.1, 0.3 and 0.5 (BBNWSCu) glasses and glass–ceramics prepared via the melt-quenching method followed by heat treatment. The base glass (BBNWSCu0) exhibited excellent thermal stability, with only 1.5% weight loss up to 850 °C, with a glass transition temperature (T_g) of about 401 °C, and an onset of crystallisation temperature of 500 °C. It was observed that the heat treatment of BBNWSCu glasses at 500 °C for 20 min produced results in the glass–ceramics with Bi₂O₃ and SrWO₄ crystalline phases, although higher CuO content reduced crystallinity. Raman analysis indicated that CuO disrupted the borate network, shifting the BO₃ vibrational band from 476 cm⁻¹ (BBNWSCu0) to 441 cm⁻¹ (BBNWSCu0.3). Optical measurements showed a decrease in the indirect band gap (E_g) from 2.50 eV (BBNWSCu0) to 2.14 eV (BBNWSCu0.5) and an increase in disorder energy (E_U). On the other hand, in the case of BBNWSCu-GC glass–ceramics, the E_g increased from 2.23 eV (for BBNWSCu0-GC) to 2.53 eV (for BBNWSCu0.5-GC), while E_U decreased significantly. PL emission studies revealed Bi³⁺ emissions at 488 nm (BBNWSCu glasses) and 492 nm (BBNWSCu-GC glass–ceramics), with additional peaks at 522 nm and 547 nm. The maximum PL intensity occurred at 0.1 mol% CuO (BBNWSCu glass), while higher concentrations led to reduced emission. The CIE chromaticity coordinates indicated stable blue–green emission, with colour purity reaching 76.7% in BBNWSCu0.1 glass and stabilised colour purity values in glass–ceramics. These results indicate that optimising CuO concentration and thermal treatment can enhance luminescence efficiency and optical quality in BBNWSCu glasses for solid-state lighting and photonic applications.

The stability of the boundary layer flow due to a stretching sheet with power-law wall velocity is under consideration. The disturbance equations are obtained under the parallel flow assumption. Assuming disturbances in the form of Tollmien–Schlichting waves, we develop a linear differential system with complex coefficients in four unknowns. A spectral method is employed to solve this system, subject to the condition that perturbations vanish both at the wall and in the far field. The neutral stability curves are plotted to identify the stable and unstable regions. Additionally, energy analysis is performed in order to provide a perspective on the actual physical mechanism influencing the instability of the disturbances. The finding indicates that flows induced by accelerated wall velocities ((n>1)) are more stable than those of flows produced by decelerated wall velocities ((n<1)).

This research examines the viability of fruit waste extract as a sustainable and eco-friendly corrosion inhibitor for mild steel in 0.5 M HCl. The extract, which is abundant in phytochemicals such as nobiletin, caffeic acid, gallic acid, and epicatechin, demonstrated a peak inhibition efficiency of 88.50% at a concentration of 100 ppm. The inhibitor creates a protective layer on the metal surface, which significantly diminishes corrosion. The study employed weight loss analysis, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), UV–visible spectroscopy, scanning electron microscopy (SEM), and quantum chemical calculations (DFT) to assess the inhibition performance of the extract. Both PDP and EIS measurements were taken in triplicate, and the results include standard deviations and error margins. SEM analysis validated surface protection, while DFT calculations indicated strong adsorption characteristics, which are attributed to the presence of electron-donating functional groups. The results imply that fruit waste extract is a promising, cost-effective, and environmentally friendly alternative to synthetic corrosion inhibitors.

Graphical abstract

We investigate the cascade decay (B^{*0}_{s} rightarrow D_s^-(rightarrow tau ^-,bar{nu }_{tau }), ell ^{+},{nu }_ell ) induced by flavor changing charged currents in the context of the Standard Model and in vector-like couplings beyond the Standard Model. We employ the helicity amplitude formalism for analysis and highlight the role of new vector-like couplings in charged current interactions. We find, in particular, that while new left handed chiral-vector like interactions contribute to the branching ratio, they do not affect the forward-backward asymmetry, or the angular observables. On the other hand, the right handed chiral vector-like coupling in the case of this decay contributes to the branching ratio, forward-backward asymmetry and the angular observables. We confirm that this difference in behavior between the left and right handed NP couplings is a general feature of charged current processes with a vector meson going to a pseudoscalar at the tree level in effective weak theory by cross checking with the cascade decays (B^{*+}_c rightarrow P(rightarrow P',mu ^+,nu _{mu }) , ell ^{+},{nu }_ell ) where P is (B_s^0) ((D^0)) and (P') is (D_s^{*-}) ((K^-)).

In this paper, we investigate almost quasi-Yamabe solitons and gradient almost quasi-Yamabe solitons on both twisted warped product manifolds (TWPMs) and doubly warped product manifolds (DWPMs). We establish necessary and sufficient conditions for these manifolds to admit such solitons and characterize their geometric properties. Specifically, we prove that if a TWPM or DWPM admits a closed almost quasi-Yamabe soliton with certain restrictions on the soliton vector field, then the manifold satisfies specific curvature conditions. We examine the behavior of gradient almost quasi-Yamabe solitons on both types of warped products and provide concrete examples. Our results extend previous work on Yamabe-type solitons to more general geometric settings, revealing new phenomena and establishing connections between soliton properties and the geometry of factor manifolds. Applications to cosmological models and general relativity are discussed.

The successful determination of second harmonic generation (SHG) and electro-optical properties largely depends on the crystalline nature of materials, which is governed by symmetry and periodicity. Designing organic materials in powdered form remains a technological challenge, yet it offers a cost-effective and time-efficient approach for device fabrication. In this work, we report the green synthesis of Schiff bases derived from p-bromoacetophenone with p-toluidine and p-anisidine, as well as from p-chloroacetophenone with p-toluidine and p-anisidine. The synthesized compounds were thoroughly characterized using experimental and computational methods to evaluate their nonlinear optical properties. Infrared spectroscopy confirmed the formation of Schiff bases through characteristic functional group vibrations, while UV–Vis spectroscopy provided insights into electronic transitions. Proton NMR and powder X-ray diffraction established the molecular structure and crystalline features of the compounds. Their optical responses were further investigated using spectroscopic ellipsometry and SHG measurements with a pulsed Nd:YAG laser set-up. In addition, quantum mechanical descriptors were employed to analyse electronic structures and electro-optical parameters associated with charge redistribution. The combined experimental and theoretical results demonstrate that these Schiff base compounds exhibit promising nonlinear optical behaviour, underscoring their potential for advanced optoelectronic applications.

The impact of pests and environmental conditions plays a critical role in determining agricultural productivity, particularly in the cultivation of rice in wetland ecosystems. This research focuses on evaluating strategies for mitigating the infestation of the rice leaf roller pest through the application of Beauveria bassiana fungi and the implementation of visual traps using mathematical modeling and optimal control theory. A nonlinear pest control model is proposed, including rice crop biomass, susceptible pests, infected pests, and Beauveria bassiana fungi as model populations. Carrying capacity of pests is assumed to be proportional to the crop biomass. Mathematical analysis is conducted to examine the existence of equilibria of the model and their stability. An optimal control problem is formulated to determine cost-effective pest management strategies and solved using the maximum principle. The numerical results support the analytical findings with data from real sources. This study demonstrates that the pest-free equilibrium is stable when the trapping rate is high. The interior equilibrium, when it exists, is globally asymptotically stable under lower rates of crop consumption and fungal infection. While the crop consumption rate can trigger a Hopf bifurcation, leading to periodic oscillations, the trapping rate and fungal release rate help stabilize the system. Finally, optimal profiles for the fungi release rate and the effectiveness of visual traps provide a cost-effective solution for managing rice leaf roller pests.

Phthalocyanine (Pc) has broad application prospects in the field of molecular devices due to its unique structure and properties. By using density functional theory (DFT) combined with the non-equilibrium Green’s function (NEGF) method, this work focuses on the influence of coinage metal electrodes on the spin polarization and thermally driven spin transport properties of uranium phthalocyanine (U(Pc)₂) device. The spin transport behavior of U(Pc)₂ varies significantly depending on the type of coinage metal electrodes. For the device with Au electrode, the electrical conductance is relatively high than Ag electrode and Cu electrode. The spin polarization of the current under bias is relatively low, reaching only 1.78% at a bias of 1 V, but it exhibits a high degree of spin polarization in the thermoelectric current when the electrode temperatures are set to 300 K and 350 K, with a polarizability reaching up to 44.81%. In contrast, the devices with Ag and Cu electrodes exhibit much higher current spin polarization, reaching 48.56% and 49.92%, respectively, at the 1 V bias. These results suggest that U(Pc)₂ devices with coinage metal electrodes hold the promise for the development of high-performance multifunctional spintronic applications.

This study investigates the effects of decoherence and squeezing on the dynamics of various kinds of quantum features–local quantum coherence, local entropy, EPR correlations, and entanglement–in the high-temperature limit of the double Caldeira-Leggett model, focusing on initially squeezed states. We compare two scenarios: (1) particles interacting with distinct environments and (2) particles coupled to a common environment. Our analysis reveals that common environments better preserve local coherence over time, whereas distinct environments accelerate decoherence. Temperature enhances decoherence and suppresses coherence revivals, while squeezing affects transient dynamics but not long-term coherence saturation. Local entropy increases with temperature and squeezing, though their underlying physical mechanisms differ. EPR correlations degrade due to environmental interactions, with squeezing initially enhancing them but failing to prevent their eventual loss. Entanglement exhibits distinct behaviors: in separate environments, it undergoes sudden death, whereas in common environments, it experiences a dark period whose duration shortens with stronger squeezing. These findings provide a comprehensive understanding of how decoherence and squeezing influence quantum correlations in open quantum systems.