Search

Multiple ion substitutions to Na 0.5 Bi 0.5 TiO 3 give rise to favourable dielectric properties over the technologically important temperature range −55 °C to 300 °C. A relative permittivity, ε r , = 1300 ± 15% was recorded, with low loss tangent, tanδ ≤ 0.025, for temperatures from 310 °C to 0 °C, tanδ increasing to 0.05 at −55 °C (1 kHz) in the targeted solid solution (1–x)[0.85Na 0.5 Bi 0.5 TiO 3 –0.15Ba 0.8 Ca 0.2 Ti 1-y Zr y O 3 ]–xNaNbO 3 : x = 0.3, y = 0.2. The ε r -T plots for NaNbO 3 contents x < 0.2 exhibited a frequency-dependent inflection below the temperature of a broad dielectric peak. Higher levels of niobate substitution resulted in a single peak with frequency dispersion, typical of a normal relaxor ferroelectric. Experimental trends in properties suggest that the dielectric inflection is the true relaxor dielectric peak and appears as an inflection due to overlap with an independent broad dielectric peak. Process-related cation and oxygen vacancies and their possible contributions to dielectric properties are discussed. [ABSTRACT FROM AUTHOR]

A new dielectric is described that meets the industry-standard lower limiting temperature of stable performance, −55 °C whilst extending the upper limit to 300 °C, with low dielectric loss, as required for the growing high-temperature electronics sector. The combined substitution of Sr and Bi ions on A sites, and Mg and Zr ions on B sites of the ABO 3 perovskite solid solution (1 − x)Ba 0.6 Sr 0.4 Zr 0.2 Ti 0.8 O 3 –xBi(Mg 0.5 Ti 0.5 )O 3 flattens the ε r -T response. At composition x = 0.2 the ε rmax temperature, and the associated tan δ dispersion peak, are each displaced to low temperatures such that a very favourable combination of low dielectric loss, tan δ < 0.015, from −60 to 310 °C and stable ε r , ∼500 ± 15% from −70 to 300 °C (1 kHz data) are demonstrated. Hence the x = 0.2 material achieves stable ε r and low loss over the technologically important target temperature range, −55 to 300 °C. [ABSTRACT FROM AUTHOR]

Ceramics in the system (1− x )Na 0.5 Bi 0.5 TiO 3 – x Ba 0.80 Ca 0.20 TiO 3 demonstrate a phase boundary between pseudo-cubic and tetragonal at 0.1 < x <0.2. There was a gradual convergence in the temperatures of a frequency-dependent inflection and peak in relative permittivity-temperature plots with increasing x : for x =0.5 and 0.6, normal relaxor-like behaviour was observed, with T m ~150 °C (1 kHz). Constriction in the polarisation-electric field hysteresis loops for the phase boundary composition x =0.1 was consistent with an electric field-induced phase transition, giving rise to an electromechanical strain, ~0.25 % at 40 kV/cm and high-field d 33 ⁎ ~640 pm/V. [ABSTRACT FROM AUTHOR]

The existence of quintessential dark energy around a black hole has considerable consequences on its spacetime geometry. Hence, in this article, we explore its effect on horizons and the silhouette generated by a Kerr–Newman black hole in quintessential dark energy. Moreover, to analyse the deflection angle of light, we utilize the Gauss–Bonnet theorem. The obtained result demonstrates that, due to the dragging effect, the black hole spin elongates its shadow in the direction of the rotational axis, while increases the deflection angle. On the other hand, the black hole charge diminishing its shadow, as well as the angle of light's deflection. Besides, both spin and charge significantly increase the distortion effect in the black hole's shadow. The quintessence parameter γ , increases the shadow radius, while decreases the distortion effect at higher values of charge and spin parameters. [ABSTRACT FROM AUTHOR]

This paper explores the neutral particle motion and collisional Penrose process in ergoregion of the braneworld Kerr black hole. We analyze the properties of event horizon, ergosphere and static limit. The particle collision in ergoregion via the Penrose process is investigated. Furthermore, we study the negative energy states and show that the sign of particle energy can be uniquely determined by the sign of angular momentum. In addition, we study the Wald inequality to determine the limits of energy extraction via the Penrose process and also find lower bound of the irreducible mass. The expression for the efficiency of energy extraction from the brane Kerr black hole is found. Finally, we compare our results with that obtained from the Kerr black hole. It is concluded that efficiency increases with the increase of rotation as well as brane parameter b of the black hole. [ABSTRACT FROM AUTHOR]

Abstract This paper explores the circular geodesics of neutral test particles on an equatorial plane around a rotating black hole. After using equations of motion of scalar-tensor-vector gravity with the circular geodesics of null-like particles, we find the equation of photon orbit. With the help of an effective potential form, we have examined the stable regimes of photons orbits. The Lyapunov exponent, as well as the effective force acting on photons, is also investigated. We examine the energy extraction from a black hole via Penrose process. Furthermore, we discuss the negative energy state and the efficiency of energy extraction. We have made compare our results with that obtained for some well known black holes models. We concluded that the efficiency of the energy extraction decreases with the increase of dimensionless parameter of theory and increases as spin parameter increases. [ABSTRACT FROM AUTHOR]

Machine learning plays a pivotal role in constructing learning models and leveraging abundant image data for feature extraction, which is essential for achieving accurate and efficient image enhancement through optimization algorithms. Traditional gradient descent methods are confined to optimizing independent parameters, while recent algorithms neglect the interdependence among parameters, resulting in prolonged iteration times for each method. To address this issue, we propose a novel Correlation-Based Gradient Descent (RGD) algorithm tailored for enhancing low-light images. RGD leverages inter-iteration results for mutual parameter transmission and optimization, employing convergence or oscillation criteria to select the final enhanced image and find the optimal parameter combination for image enhancement, thereby enhancing parameter optimization efficiency. Specifically, each iteration is divided into multiple operations, with each operation adopting different enhancement schemes. During each iteration, the results of different operation parameters are shared, which facilitates the discovery of optimal parameters for low-light image enhancement. Subsequently, corresponding enhancement operations are performed based on this parameter combination to optimize standard indicators. Our experiments on medical and natural low-light scenarios demonstrate that our RGD method achieves a significant reduction in iteration time, with at least a 17% decrease compared to exhaustive loop methods. [Display omitted] • A gradient descent optimization algorithm named Relevance Gradient Descent (RGD) for combining the parameters to joint optimization is proposed. • RGD has excellent enhancement performance, which has higher time accuracy than traditional independent parameter gradient descent algorithms. • RGD has the ability to enhance low illumination images in both natural and medical scenes. [ABSTRACT FROM AUTHOR]

TNFα and NF-kB contribute in activation of pro-inflammatory signaling pathways and complications of coronary artery diseases (CAD). Current study highlights novel properties of Au (15 ± 2 nm), ZnO (77 ± 45 nm) and MgO (11 ± 4 nm) nanoparticles (NPs) as possible anti-inflammatory agents with greater efficacy and lower toxicity. Decrease in TNFα and NF-kB levels in Single Vessel Disease (SVD), Double Vessel Disease (DVD) and Triple-Vessel coronary artery disease (TVD) macrophage and lymphocyte cultures at varying concentrations of NPs has been studied to find an effective therapeutic concentration (ETC). Au and MgO NPs exhibits 5 µg/ml ETC compared to 1 µg/ml ZnO in all three CAD categories with negligible toxicity. ZnO remains most statistically significant (p < 0.001) in SVD and TVD cultures whereas MgO shows efficacy in DVD and TVD cultures with more than 50% reduction in TNFα and NF-kB levels at their respective ETCs. Au NPs exhibit prominent effect in DVD cultures. The mRNA expression results support the down-regulation of TNFα and NF-kB after NPs exposure in respective cultures. Findings of this prospective observational cohort study suggest use of NPs as an alternate anti-inflammatory agent in coronary artery and other diseases. [ABSTRACT FROM AUTHOR]