Applied Physics A最新文献

Manganese is an essential micronutrient for all living organisms and plays a crucial role in bone metabolism. The purpose of this study was to investigate the effects of manganese on the structure and chemical dissolution behavior of bioactive glasses, as well as its effects on in vitro biological activity and oxidative stress levels. Manganese doped bioglass was synthesized by sol-gel method. Its structure was studied using FTIR combined with Raman spectroscopy. The in vitro mineralization performance in simulated body fluids was analyzed using X-ray diffraction, FTIR and ultraviolet spectroscopy. The antioxidant capacity of manganese doped bioglass was studied using MC3T3-E1 cells against H₂O₂ induced damage. The doping of manganese caused slight changes in the bioglass structure, and enabled it to obtain crystalline phases of calcium manganese silicate and calcium silicate through calcination. All bioglass exhibited good ability to form hydroxyapatite. Compared to the parent bioglass, manganese doping significantly enhanced the dissolution and biomineralization behavior. The protective potential of manganese doped bioglass exhibited dose-dependent effects within a limited concentration range, with excellent anti-oxidant ability observed at low doses of doping. Manganese doped bioglass has potential applications in bone regeneration and healing.

The effect of anisotropy, which is crucial for manufacturing single crystals, was investigated in this study by performing nanoindentation experiments on the Si/C plane of single crystal 4H-SiC with the edge of Berkovich indenter toward with two different crystal orientations of ([11overline{2} 0])/([1overline{1} 00]). On the Si plane, when the edge was toward crystal orientation ([11overline{2} 0])/([1overline{1} 00]), the indentation hardness is 39.37/39.77 GPa, the elastic modulus is 528.16/513.88 GPa, and the fracture toughness is 3.286/2.609 MPa·m^1/2. On the C plane, when the edge was toward crystal orientation ([11overline{2} 0])/([1overline{1} 00]), the indentation hardness is 43.66/41.91 GPa, the elastic modulus is 522.24/546.54 GPa and the fracture toughness is 2.826/2.705 MPa·m^1/2. At the same time, the Vickers hardness crack induction method was used to calculate the fracture toughness, regardless of the Si or C plane, the fracture toughness value of the crystal orientation ([11overline{2} 0]) is generally greater than that ([1overline{1} 00]). Molecular dynamics (MD) indentation simulations were carried out with the indenter edge facing different crystal directions of the Si plane. There is obvious anisotropy in the depth of the amorphous atomic layer, the number and proportion of dislocation nucleation, and the shear strain expansion. Although microscratch experiments combined with the analysis of scratch variables and the optical topography of scratches, it is concluded that the scratch deformation damage towards the crystal orientation ([1overline{1} 00]) is smaller. This study can provide theoretical guidance for the ultra-precision machining of the anisotropy of 4H-SiC crystal structure.

This paper presents a metasurface based reconfigurable transmissive linear polarizer (TLP) that demonstrates four critical polarization states: 0°, ± 45°, and 90°, with a polarization angle error of ± 10% or less across different states. The polarizer comprises a partially reflective surface (PRS), a polarization deflection surface (PDS), and a polarization selection surface (PSS). The switching among these four polarization states is achieved by controlling the surface currents on the PDS and PSS using PIN diodes, in conjunction with the functional interplay of each layer. Layer-by-layer design guidelines are provided, elucidating the polarization conversion mechanism. A prototype has been successfully fabricated and tested, with the measurement results exhibiting good agreement with the simulation outcomes. The measurements reveal that, upon illumination by an x-polarized wave, the polarizer can perform four distinct functionalities within an overlapping bandwidth of 2.2–2.6 GHz (16.7%), maintaining a transmission coefficient above − 3 dB across this entire frequency range. This polarizer serves as a valuable reference for polarization control technology in single-polarized antennas, holding promising potential for applications in fields such as wireless communication and electronic countermeasures.

This study investigates the influence of substrate configuration variations on the surface properties and contact angle of nanostructured aluminum-doped zinc oxide (AZO) thin films deposited via RF magnetron sputtering on glass substrates at room temperature. Three distinct substrate configurations—Standard Planar Position (SPP), Glancing Angle Deposition (GLAD), and Twisted Standard Planar Position (TSPP)—were employed to explore their impact on the films structural morphology and crystallinity, characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Wettability, characterized by contact angle and surface energy, was assessed using static measurements with a range of probe liquids, including water, diiodomethane, and ethylene glycol. Our findings demonstrate the ability to tailor AZO films to achieve specific crystalline orientations without altering the growth temperature. Substrate rotation and configuration modifications significantly impacted AZO film surface energies, revealing enhanced hydrophilicity evidenced by reduced contact angles compared to control samples. Using the Owens–Wendt-Kaelble method, we quantified both polar and dispersive surface energy components, observing significant increases in both for AZO thin films. These results highlight heightened surface reactivity, suggesting potential applications in diverse wetting-dependent contexts, such as reinforcement of polymeric materials and self-cleaning surfaces and anti-reflective coatings for photovoltaic devices.

Carbon nanotubes (CNT) have attracted much attention due to their wide range of applications, but the complex and time-consuming preparation of CNT by the traditional chemical vapor deposition (CVD) method has limited their large-scale production. In this study, we propose an innovative “one-step” CNT growth process to simplify catalyst preparation. The significant advantage of this method is that it reduces the time consumption by 90% compared with other catalyst preparation methods. Aluminum foil was found to outperform other materials as a substrate and catalyst loading significantly affected the morphology and quality of CNT. High-density, low-defect, high-crystallinity, and high-quality CNT could be grown on aluminum foil at the optimal loading (e.g., 0.10 mol/L.) In addition, the growth of CNT is affected synergistically by catalyst-substrate interfacial interactions, temperature, and aqueous solution content. In particular, CNT arrays with a diameter of 20 nm were successfully prepared on an iron catalyst calcined at 660 °C. These findings are important for large-scale, low-cost production of high-quality CNT.

The Cd-boro phosphate glasses doped with Nd₂O₃ were prepared via melt quenched process. The impact of Nd³⁺ ions on the structural, mechanical, optical properties and γ-ray shielding abilities of the boro-phosphate glasses was studied. XRD patterns have demonstrated that the samples are amorphous. The incorporation of Nd₂O₃ in the glasses led to increase the glass densities (from 3.144 to 3.233 g/cm³) as result of high molar mass, and also increased molar volume of doped glasses from 39.26 to 39.41 cc/mol due to the large ionic size of Nd₂O₃. The obtained data showed that Nd₂O₃ is a major contributor to increasing the elastic modulus and derived hardness values ​​of the studied glass when replacing it with boric. In the range of 270–1100 nm of UV-Vis, the optical absorption spectra showed nine absorption bands attributed to the 4f³-4f³ transitions inside Nd³⁺ ions in the investigated glass specimens. The indirect optical gap values reduced, whereas linear-(n_o) and nonlinear-(n₂) refractive indices increased as Nd₂O₃ content increased in the glass network. The criterion metallization (M) was declined. Mass-(MAC) and linear-(LAC) absorption factors increased, whereas half-(HVL) and tenth-(TVL) value layers declined as Nd³⁺ ions increased. The obtained results showed that the fabricated Nd₂O₃-doped glasses potentially beneficial for optical and radiation shielding applications.

This paper investigates laser wakefield acceleration (LWFA) of electrons using two-stage gas nozzles and ionization injection schemes. We present Fourier–Bessel particle-in-cell (FBPIC) simulation results for LWFA of electrons driven by Bessel-Gauss (BG) laser beams in hydrogen and hydrogen-nitrogen gas mixtures with varying nitrogen concentrations. A TW-class ultrashort 10 fs laser beam is employed to study the effect of different nitrogen gas concentrations on the electron beam quality up to an acceleration distance of 1 mm. Results indicate that electron energy is the lowest in pure hydrogen, while adding nitrogen enhances energy levels. Moreover, it is found that the highest electron energy is obtained when the nitrogen concentration is 1%, and the electron energy reaches around 150 MeV. Higher nitrogen concentrations (> 1%) also lead to reduced electron energy, demonstrating a declining trend with further increases.

The paint layer from the surface of 2024-T3 aluminum alloy aircraft skin was stripped down to three stages through adjusting the laser energy density of infrared nanosecond pulse laser: oxidation layer (OXL), exposed aluminum substrate (EAS) and melted layer of aluminum alloy (MLA). Subsequently, the microstructure of the aluminum alloy aircraft skin substrate after paint removal was analyzed through a series of examinations. Then, the influence of laser paint removal on the tribological properties of the substrate material was investigated by performing reciprocating wear tests. Finally, the interaction between the microstructure of the substrate and its wear performance was explored. The results show that with a reasonable laser energy density, laser paint removal does not significantly alter the near-surface microstructure and mechanical properties of the substrate. However, excessive laser energy density can cause grain refinement on the surface layer of the aluminum alloy skin, increase surface hardness, and reduce the wear rate. The information could provide a guide in practical application of laser cleaning in aircraft skin paint removal.

This work aims to tune the structural and optical properties of TiO₂/FTO heterojunction by cobalt doping for optoelectronic applications. Undoped and cobalt doped TiO₂/FTO heterojunctions were prepared by the spray pyrolysis method. The morphological and elemental investigations were performed using the scanning electron microscopy technique. The FT-IR spectroscopy was applied to investigate the functional groups and structures’ modifications of the samples. The XRD technique was used to explore the structural properties of all samples. Clear modifications in the investigated structural parameters were obtained. The UV-Vis. spectroscopy technique was used to explore the linear/nonlinear optical performance of all heterojunctions. The Herve-Vandamme model was applied to examine the refractive index n. It is found that all optical parameters (refractive index, extinction coefficient, dielectric constants, optical conductivity, etc.) are altered due to cobalt doping. The optical analysis reveals that linear susceptibility, nonlinear third-order susceptibility and nonlinear refractive index of TiO₂/FTO heterojunction are tuned through cobalt doping. The obtained findings in this work nominate the potential candidacy of cobalt doped TiO₂/FTO heterojunction in plenty of optoelectronic applications.