International Journal of Mechanical and Materials Engineering最新文献

This investigation introduces a novel method for the fabrication of ZnSe thin films on glass substrates through the spin coating technique which employs thiol-amine cosolvents. The thiol-amine co-solvent system efficiently dissolves several metal and metal chalcogenide precursors, facilitating cost-effective, and low-temperature solution-based deposition compatible with flexible substrates. The synthesized ZnSe thin films underwent air annealing at temperatures between 250 and 350 °C, thereby improving their structural and optical characteristics. The polycrystalline nature of ZnSe was elucidated via X-ray diffraction (XRD) analysis, while scanning electron microscopy (SEM) assured the rise of surface smoothness and uniformity with annealing temperature. Energy-dispersive spectroscopy (EDS) analysis indicated near-stoichiometric ZnSe composition, and Fourier-transform infrared (FTIR) spectroscopy identified Zn–Se stretching vibrations in the 960–1120 cm⁻¹ range. The optical data demonstrated high transmittance with an optical bandgap of 3.32–3.85 eV. Furthermore, optical data of ZnSe were embarked for computation of Ge-on-ZnSe waveguide with SiO₂ cladding for long-wave infrared (LWIR) light. The waveguide showed a remarkable power confinement factor (PCF) of ~ 0.99 with nearly 1 dB/cm loss at a laser wavelength of 8 μm. These outputs are highly optimistic for the fabrication of solution-processed ZnSe for LWIR photonic integration.

The Di barium magnesium Di-silicate Ba2MgSi2O7 (BMSO) with single-doped Tb3 + , Eu3 + phosphors, and co-doped Tb3 + /Eu3 + phosphors were prepared by the combustion method. The structural characterisation was studied by X-ray diffraction (XRD) technique, and an optical property (PL, ML) and luminescence decay curves were utilised to describe each phosphor’s properties. Profound green emission due to the Tb3 + 5D4-7F5 transition was optically canvassed in the Tb3 + single-doped Ba2MgSi2O7 sample, and it was determined that the appropriate concentration quenching process involved a diople-diople interaction. A huge overlap between Tb3 + emission and Eu3 + excitation spectra has consequences for strength transfer from Tb3 + to Eu3 + . Based on the concentration quenching approach, it was found that the energy transfer mechanism is a quadrupole–quadrupole interaction, and the energy transfer critical distance from Tb3 + to Eu3 + ions is predicted to be (6.7). Additionally, by altering the ratio of Tb3 + and Eu3 + concentrations in Ba2MgSi2O7:Tb3 + Eu3 + phosphors, white light emission was produced. According to all the findings, the single-component white light-producing phosphor BMSO: Tb3 + Eu3 + is a promising one.

A primary objective of this study was to evaluate how the more fundamental blending approach to optimize the packing of pigments in coatings can potentially be used to improve the packing of the asphalt-aggregate blends. In the course of this study, a new way to characterize the efficiency of the packing of particles was developed from the particle packing fraction analysis originally included as a component of a previously published suspension viscosity model. This new percent packing efficiency introduced in this study was found to be particularly useful in evaluating the packing efficiency for particle distributions of all sizes. The large scale of the aggregates in asphalt previously published in the Goode and Lufsey study along with the properties included in their report was very useful in developing the formulation for this new percent packing efficiency analysis. A property analysis of the Goode and Lufsey study data found that the minimums for the mineral voids and the air voids appear to correspond with the maximums for percent packing efficiency as well as the maximums of the bulk-specific density. These results appear to indicate that the percent packing efficiency can be a significant measure of the efficiency of particle packing for aggregate blends. These preliminary analysis results also suggest that the percent packing efficiency may also be able to detect unstable particle packing applications for particle distributions of all sizes as well as potentially unstable asphalt/aggregate applications. As anticipated, the Goode and Lufsey maximum density standard gradation did yield the maximum percent packing efficiency followed in order by other standard gradations including a stone matrix gradation, the superpave gradation, and finally, a Bailey gradation. Finally, several new gradations were identified in this study that could potentially offer significant property improvements over both gradation 3 from the Goode and Lufsey study as well as the other current aggregate gradation standards for the asphalt industry.

Hydrogels are versatile materials that can be used in biomedical applications, where their multifunctional capabilities can be leveraged as sensors, actuators, drug delivery devices, and chemomechanically responsive materials. This review article explores the diverse applications of hydrogels and their chemomechanical response. The foundations of hydrogels, encompassing their physics, chemistry, and diffusion properties, are presented, providing a comprehensive understanding of their behavior. Synthesis and fabrication challenges, such as batch consistency, storage stability, degradation, and inconsistent mechanical swelling behavior, are addressed. Hydrogels are often characterized by using a variety of methods to define the full scope of their material properties, including structural analysis, UV–visible spectroscopy, dynamic mechanical analysis, scanning electron microscopy, rheology, optical microscopy, pressure sensing, and nuclear magnetic resonance. The current state of the art of hydrogels is explored, focusing on the physical and chemical properties and some theories and mathematical models that describe their behavior. We discuss drug delivery, diffusion studies, controlled release, sustained drug interactions, and various drug delivery methods, ranging from transdermal to ocular to mucous membranes. We further present hydrogels as viable candidates for 3D-printed devices, including sensors and actuators, where we examine specificity, selectivity, biomarker interactions, and molecularly imprinted polymers. The emerging areas of 3D-printed hydrogel devices, microfluidics, and soft robotics and their potential uses are highlighted. Finally, limitations, opportunities, and future research directions are proposed to enhance commercial viability and define potentially valuable insights for future advancements in the field. 

The resurgence of interest in lanthanide coordination complexes due to their diverse applications has been increasing for past decade. These lanthanide complexes have found applications such as catalysts, sensors, optoelectronics, light sources, and modified semiconductors. The modifications in the lanthanide complex chemistry due to the use of different complexation agents enhanced the luminescence properties by varying the emission bands, stoke shifts, and lifetimes accordingly. This versatile nature of lanthanide complexes increased our interest to make a good contribution to the field. The complexes of lanthanum, europium, and novel binary complex of La and Eu metals with 1,10-phenanthroline (Phen) and 5-sulfosalicylic acid (SSA) were synthesized by co-precipitation method. Different physicochemical techniques like analytical and spectroscopic were used to characterize the ligands and complexes. The coordination of ligands with metals in complexes was confirmed by FTIR and UV spectroscopy. The surface morphology of nine coordinated La-complexes and seven coordinated Eu complexes was investigated by SEM micrographs. The X-ray crystallographic analysis revealed that all the complexes exhibit a triclinic crystal system. All the complexes were found to exhibit self-reversed magnetic hysteresis (SRMH). The luminescence and magnetic properties of mixed metal complexes are enhanced as compared to their mononuclear analogs.

Additively manufactured scandium-doped AA5083 aluminum-magnesium alloy (AA5083-Sc) has a higher yield strength compared to the undoped version. However, AA5083-Sc is prone to pitting and microbiologically induced corrosion in seawater. Chemical conversion coating using aqueous cerium (III) nitrate, Ce(NO₃)₃, provides only a moderate improvement in corrosion resistance. Electrochemical anodic oxidation of the alloy’s surface in a 0.2-M Ce(NO₃)₃ solution at pH 4, conducted over an extended period at low current density, significantly enhances its corrosion resistance. After undergoing surface oxidation, the alloy demonstrates corrosion resistance for more than a year when submerged in aerated water containing 3.5% sodium chloride and two types of corrosion-inducing bacteria: Vibrio penaeicida and Thalassospira profundimaris. Electrochemical oxidation transforms the alloy surface oxide from an insulator to a p-type semiconductor, effectively slowing down the cathodic reduction reaction without hindering anodic oxidation. Since the rate of electrochemical corrosion is determined by the slower of two reactions—metal oxidation and the accompanying cathodic reaction—our findings suggest that cathodic reaction slowing is sufficient to reduce the corrosion rate. Additionally, cerium is known for its antifouling properties, and treating the surface with cerium also helps to minimize biofouling and microbial colonies.

Graphical Abstract

Combining ceramic materials such as MgO and ZrO₂ can have a wide chemical and technological application. In this context, the sol–gel method is a very noble method for preparing mixed oxides, as it allows the control of their textural and surface properties. This paper aims to evaluate the structural and morphological properties of MgO-ZrO₂ mixed oxides as a function of their composition, for which solids of 10, 25, 50, 75, and 90% mol of ZrO₂ were synthesized by the sol–gel method. The obtained materials were characterized by N₂ physisorption, X-ray diffraction, scanning electron microscopy and diffuse reflectance, Fourier transform infrared, and Raman spectroscopy. The results showed that the textural properties of MgO improved by adding 25% ZrO₂, such that this solid showed the highest surface area (124 m²/g) and pore diameter of 12 nm. FTIR, RD-UV–Vis, and Raman spectra showed the presence of O–H chemical bonds due to the hygroscopic character of the materials. In contrast, XRD results showed MgO in the periclase phase and ZrO₂ mostly in the tetragonal phase. It was also observed that the bandgap energy increases slightly as a function of ZrO₂ content. On the other hand, SEM micrographs showed that the increase of ZrO₂ changes the morphology of the particles, size and shape.

Wastewater pollution caused by toxic dyes from the textile industry is a global challenge, threatening agricultural productivity, food security, and access to clean water for livestock. In recent years, photocatalytic degradation of organic pollutants using semiconducting materials has emerged as a promising approach for sustainable wastewater treatment. We present a cost-effective synthesis method for lithium manganese oxide (Li₂MnO₃), which aggregate to form a densely packed microcrystalline powder, with smooth-stone morphology, and monoclinic crystal structure. Optical characterization reveals broad visible light absorption, strong infrared reflectance and an optical bandgap of 2.1 eV, suggesting potential applications in radiation-resistant coatings. Moreover, the obtained Li₂MnO₃ material effectively degraded Eriochrome Black T, a common textile dye, with efficiencies up to 73% for 5 × 10⁻⁵ M solutions, under illumination at 625 nm, within 60 min. These findings underscore the potential of Li₂MnO₃ nanostructured microcrystals for wastewater treatment applications.

Thin film technology has made significant contributions to the field of photocatalysis through improvements in surface properties and a decrease in material costs. Therefore, the present study aims to evidence the properties that Pd can confer to TiO₂ thin films prepared by chemical vapor deposition technique and to verify their effectiveness as photocatalysts in the degradation reaction of the carbinol-based malachite green dye. TiO₂ films with different nominal Pd contents (2.8, 3.7, 4.6, and 6.4 at. % Pd) synthesized by CVD at 400 °C and 1 Torr pressure exhibit significant changes in their crystal structure, morphology, and electronic properties. On the one hand, at low concentrations (2.8 and 3.7 at. % Pd), substitutional doping is promoted. In contrast, the increase in concentration (4.6 and 6.4 at. % Pd) encourages the formation of PdO and PdTiO₃ phases, as indicated by X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy results. The anatase phase is partially inhibited by other phases, such as Pd–O and Ti-Pd–O; consequently, the grain size that constitutes the film is considerably reduced, and microstrains are increased. On the other hand, the study of the optical properties reveals a decrease in the bandgap energy and the recombination velocity of the charge carriers, resulting in a maximum degradation of 67% of the dye, which is obtained with film 4.6 at. % Pd, attributed to a synergistic effect between the observed properties.

This study reports the development of printable magnetic nanocomposites designed with a novel nanotextured surface, featuring nanospikes—composed of iron oxide magnetic nanorods—distributed with a subtle vertical alignment tendency, inspired by the Beam Drop Inhotim artwork,termed here “Beam Drop Inhotim Surfaces” (BDIS). The nanorods were synthesized via reflux and hydrothermal routes, then incorporated into a commercial photopolymerizable resin, forming a printable magnetic nanocomposite. It was printed using masked stereolithography (MSLA) 3D printing process, with real-time application of a neodymium magnet-induced magnetic field during photopolymerization—an innovative approach compared to plasma or laser surface treatments used in other studies. Characterizations of the nanorods, photosensitive resin, and nanocomposite, conducted via Fourier-transform infrared spectroscopy, magnetic force microscopy, scanning electron microscopy, and vibrating sample magnetometry, confirmed successful nanocomposite production without compromising printability, enabling a unique nanotextured surface.

Graphical Abstract