This study investigates aluminium oxide (Al2O3) nanoparticle-enhanced CK-4 10 W-30 engine oil to improve the thermal, tribological, and oxidation performance of commercial lubricants. Nanolubricants were synthesised using a two-step dispersion at concentrations of 0.25, 0.50, and 1.00 wt% and were characterised for stability using UV–Vis spectroscopy, zeta potential, X-ray diffraction, TGA, DSC, DLS, FTIR, and TEM were used to analyse the morphological, chemical, and thermal properties of the developed nanolubricants. The rheological properties of developed nanolubricants were assessed by the rheometer at 20℃, 50℃ and 80℃. Tribological performance was assessed with a four-ball tribotester under standard ASTM conditions at different loading conditions (390, 400, 410 and 420 N).The results demonstrated homogeneous nanoscale dispersion and good stability of the nanolubricants, with zeta potential values approaching ± 30 mV. Among all formulations, the 0.50 wt% Al2O3 nanolubricant exhibited the best overall performance. TGA and DSC analyses indicated improved thermal stability and delayed thermal degradation compared with the base oil. FTIR analysis confirmed the absence of adverse chemical interactions between the Al2O3 nanoparticles and the CK-4 10 W-30 engine oil. Tribological evaluation further revealed significant reductions in the coefficient of friction and wear scar diameter relative to pure CK-4 oil, with the optimum performance observed at 0.50 wt% concentration due to enhanced load-carrying capability and the formation of a protective anti-wear tribofilm.
This study investigates the thermo-hydraulic transport behavior and optimization of aluminium nitride (AlN) nanofluids prepared from 50-50 volumetric mixtures of deionized water and Mono ethylene glycol (DIW-MEG) flowing through rectangular microchannels for advanced electronic cooling applications. AlN nanoparticles with volume fractions ranging from 0.01% to 1.0% were dispersed in DIW-MEG base fluid, and the thermophysical properties were experimentally characterized over a temperature range of 298.15K- 318.15K. Numerical simulations were performed using multiphase Eulerian inhomogeneous model with a phase-coupled SIMPLE algorithm in ANSYS Fluent 2022 R1. Three rectangular microchannel configurations CH_A8, CH_A7 and CH_A6 with aspect ratios of 8, 7, and 6 respectively were analyzed under steady laminar flow conditions (Re = 20- 140), with a uniform heat flux of 60 W/cm2 imposed on the heated bottom wall of the substrate of the channel. The effects of nanoparticle concentration, Reynolds number, and channel geometry on Prandtl number, Nusselt number, heat transfer coefficient, pressure drop, and THPP were systematically examined. The results demonstrated that reducing the aspect ratio from 8 to 6 significantly enhanced convective heat transfer due to stronger thermal boundary layer interaction and improved fluid mixing, although pressure drop also increased. Therefore, the Pareto based optimality method is used to tradeoff between the heat transfer coefficient and pressure drops, with the highest THPP of 1.36 achieved for the CH_A6 configuration at 1.0% volume fraction and Re = 20. Furthermore, a logarithmic-linear regression correlation for Nusselt number was developed with an R2 value of 0.9373 shows strong fit.
Phosphor materials doped with rare-earth ions have gained significant attention for their potential applications in solid-state lighting and display technologies. However, achieving high color purity and efficient luminescence is challenging. To address this limitation, we synthesized a series of Sm3+-doped Ca3La3(BO3)5 phosphors (Ca3La3(BO3)5:xSm3+; x = 0.005, 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, or 0.13 mol) via a sol–gel method. The structural and luminescence properties of the Ca3La3(BO3)5:xSm3+ phosphors were analyzed by x-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and photoluminescence (PL) measurements. XRD analyses confirmed that the phosphors possess a hexagonal crystal structure. FT-IR spectroscopy confirmed the presence of BO3 groups, with characteristic B–O stretching vibrations observed in the 1500–1000 cm−1 range and B–O–B bending modes at 520, 616, and 741 cm−1. These findings confirm the structural integrity of the borate network in Ca3La3(BO3)5:xSm3+ phosphors. The optical energy bandgap was estimated using diffuse reflectance spectroscopy. The PL excitation band was identified as the charge-transfer band of Sm3+. The emission spectra revealed three distinct peaks in the 500–750 nm range, corresponding to the 4G5/2 → 6HJ (J = 5/2, 7/2, or 9/2) transitions of Sm3+. The intensity of the peaks in the PL spectra of Ca3La3(BO3)5:xSm3+ increased as x increased up to 0.03 mol but decreased at higher x values. Analyses based on Judd–Ofelt theory and optical absorption data indicate that the synthesized phosphors exhibit significant emission cross-sections and effective line widths. Under 401 nm excitation, the Ca3La3(BO3)5:0.03Sm3+ phosphor exhibited high color purity (82–90
To develop energy-efficient devices for a sustainable future, this study investigated thulium-doped lanthanum zirconate (La2Zr2O7) as a phosphor for solid-state lighting. The material was synthesized via the sol–gel technique. X-ray diffraction (XRD) analysis was used to confirm the phosphor phase, with no impurity peaks observed. The phosphor is single-phase, has a pyrochlore cubic formation, and the crystallite size was found to be around 36 nm. Fourier transform infrared (FTIR) spectroscopy was used to identify the various bonds in the host lattice. The energy bandgap of the optimized phosphor was calculated to be 4.87 eV using the diffuse reflectance data by applying the Kubelka–Munk function. Photoluminescence (PL) emission and excitation studies were also conducted on these phosphors. A sharp blue luminescence, centered at 460 nm under 360 nm excitation, was observed, originating from the 1D2 → 3F4 transition. The intensity of this luminescence increased up to 0.05 mol of Tm3+ ions in the host lattice. Dipole–dipole interaction was confirmed as the interaction between the activator ions, leading to the quenching of the concentration. The Commission Internationale de l’Eclairage (CIE) coordinates of the prepared phosphors lay in the blue region, with the optimized sample exhibiting the highest color purity of around 76
Monitoring organophosphorous pesticides (OPs) is indispensable for ensuring food safety, protecting human health, and upholding ecological balance. In this study, ZnS-grafted Ti3C2Tx nanohybrid was synthesized by using a one-pot hydrothermal method and deposited electrophoretically onto an indium tin oxide (ITO) coated substrate, which was further immobilized with a mixture of acetylcholinesterase (AChE) enzyme and chitosan (CS) in the presence of glutaraldehyde to construct AChE-CS/ZnS@Ti3C2Tx/ITO biosensor for chlorpyrifos (CPE) detection. The structural and morphological characterization of the synthesized material was conducted by using X-ray diffraction (XRD), Fourier transform-infrared (FTIR) spectroscopy, Field-emission scanning electron microscopy (FESEM) coupled with energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) analysis, and Raman spectroscopy, which confirms a successful grafting of zinc sulfide nanoparticles (ZnS NPs) and predominant –OH surface terminations on Ti3C2Tx that encourage enzyme immobilization. The constructed sensor demonstrates a linear range of 1 pM – 100 nM, a low limit of detection (0.11 pM) and sensitivity (11.28 µA pM− 1 cm− 2) with good reproducibility, stability, and appreciable recoveries (91.17-104.72
