Journal of Particle Science and Technology
Volume:9 Issue: 1, Spring 2023

Fe3O4@SiO2/AEPTMS/Fe(OTf)3 is a stable, effective, and magnetic nanocatalyst easily prepared and characterized using FT-IR spectroscopy, SEM, TEM, and VSM techniques. This nanocatalyst was successfully applied for trimethylsilylation of numerous alcohols (primary, secondary, and tertiary alcohols) with hexamethyldisilazane in 1 ml dichloromethane at room temperature to their corresponding trimethylsilyl (TMS) ethers. Quick response times and a simple reprocessing procedure are two fascinating advantages of this nanocatalyst. This catalyst protects alcohols at 1.5 min, and turn-over frequency (TOF) values for the presented catalytic system have been estimated 833 h-1.

In the present work, cordierite single-phase powders with high purity were synthesized during a two-step process. First, magnesium aluminate spinel powders were prepared via the KCl-assisted solution combustion route. Then, synthesized spinel particles and nanosilica were planetary milled for 24 h, followed by post-heating at different temperatures for 3 h. Results showed that post-heating at 700 and 900 °C did not change the sample phases. However, a magnesium aluminate spinel phase appeared for particles post-heated at 1100 °C. Further heating up to 1200 °C led to the phase transformation of amorphous silica to cristobalite, which reacted with magnesium aluminate spinel to form a cordierite phase. Finally, at 1300 °C, the remaining spinel and cristobalite reaction was completed, and single-phase cordierite powders without additional phases were obtained. Moreover, there was considerable radial shrinkage, and scanning electron microscope micrographs showed the liquid phase sintering of cordierite occurred.

The present study aims to investigate the thermal properties of low-quantum structures (LQS) with a described non-central potential. Additionally, the study investigates the influence of relativistic parameters such as the constituent mass (effective mass) of particles and the effect of thermal properties. The magnitude of distortion of an LQS due to a non-central potential was found to have a profound effect on the system's quantum and thermal properties, which is crucial to understanding the behavior of practical quantum systems in an LQS. This paper studies the critical concepts in the fundamental optimization of mass and thermal properties of interactions in LQS based on canonical operators. It explores and analytically calculates the radial part of the Schrödinger equation at finite temperatures with two intertwined spaces using the normal ordering method in a combination of the Coulomb potential and the distortion potential. We provide analytical expressions for the ground state energy eigenvalues to define the zeroth approximation with the quantum and thermal effect and properties. Results showed that the energy of a system decreases with an increase in temperature and strength of the distortion.

In this study, steel particles were used to reinforce the magnesium matrix. To fabricate the magnesium-steel particle composite,  steel particle preforms were made in different sizes; some were sintered at 1000 - 1200 ℃ and some without sintering. These preforms were preheated at 750 °C and then infiltrated with melted magnesium with the squeeze casting method. The microstructure of the preforms and the composites were investigated by SEM and optical microscope. Microhardness and compression tests were performed to investigate the mechanical behavior of the composites. The microstructure study showed the rigid connectivity between the steel particles in the interpenetrating phase composites. Also, hardness and compression test results showed higher hardness (61 VHN) and strength (218 MPa) for the composites with 1mm steel particle size sintered at 1200 ℃. Hence, the composites with 3D-dimensionally interconnected steel particles show significant changes in their mechanical properties.

Quinones are considered a class of organic compounds having a quinonoid group and are the ultimate electron acceptors. Due to this property, they have favourable redox potential and the ability to form stable hydrogen bonds. Luminescence quenching is one of the most important techniques used to get information regarding the structure and dynamics of a luminophore. A variety of transition metal complexes have been synthesized and studied to comprehend the quinones' electron-accepting characteristics. Among these, Ru(II) polypyridyl complexes have widespread applications in electron transfer reactions due to their well-defined photophysical and photochemical stability. The reaction of excited state Tris(4,4'-dimethoxy-2,2'-bipyridine)ruthenium(II)tetrafluoroborate [Ru(dMeObpy)3](BF4)2 complex with quinones was investigated through photoinduced electron transfer reaction in homogeneous and microheterogenous medium. The luminescence quenching technique has been used to study this reaction. The complex has an absorbance maximum of 448 nm in aqueous medium. The quenching rate constants were deduced using the Stern-Volmer equation. The interaction between the complex and the quinones in a cationic micellar medium, cetyltrimethylammonium bromide (CTAB), was analyzed based on electrostatic interaction and hydrophobicity. The plot between RTlnkq vs. reduction potential of the quinones, as well as the transient absorption spectra, confirmed the oxidative nature of quenching of the ruthenium complex in the presence of quinones. The quenching constant values are influenced by many factors, such as the nature of the ligand, medium, size, and structure of quenchers, and electron transfer distance between the donor and the acceptor. The formation of Ru3+ species is confirmed by its characteristic absorption at 600 nm.

The study examined the potential use of MIL-53(Al), a metal-organic compound created through solvothermal synthesis, as a support for iron catalysts in Fischer-Tropsch Synthesis (FTS). Fischer-Tropsch synthesis is a crucial aspect of Gas-to-Liquid (GTL) technology used in the petrochemical industry to produce light olefins. The catalyst's activity was assessed under specific conditions, including a gas hourly space velocity (GHSV) of 2700 h-1, a hydrogen to carbon monoxide (H2/CO) feed ratio of 2:1, temperatures ranging from 310 to 330 ℃, and pressures ranging from 5 to 9 bar. The feasibility study indicated that MIL-53(Al) has the potential to be a suitable support for iron catalysts in FTS, resulting in the production of light olefins (24%) at high temperatures and low pressure.